The present invention provides water soluble ethylenically unsaturated monomers selected from the group consisting of formula I and II

This invention relates to new ethylenically unsaturated monomers derived from the reaction of epoxy substituted alkenes and sodium bisulfite. The instant invention is also directed to polymers derived from the above ethylenically unsaturated monomers. This invention also relates to a new ethylenically unsaturated monomer derived from the reaction of 3,4-epoxy-1-butene and sodium bisulfite. The invention is also directed to a new compound known as 4-hydroxy-3-sulfonic acid-1-butene and metallic salts thereof. This invention further relates to polymers and copolymers derived from 4-hydroxy-3-sulfonic acid-1-butene, metallic salts thereof and ammonium and amine salts thereof. The present invention is also directed to self-dispersing polymers and copolymers containing the novel ethylenically unsaturated monomer of the instant invention.
This invention also relates to polymerizable sulfonic acid derivatives, to processes for their production and to their use as emulsifiers for aqueous emulsions. The invention is further directed to polymers synthesized from the emulsifiers and other monomers.
The present invention also relates to a method of producing an aqueous polymer emulsion having excellent stability. More specifically, the present invention is also intended for producing an aqueous emulsion containing substantially no emulsifier and relates to a method of producing an aqueous polymer emulsion remarkably elevated in chemical stability by copolymerizing a specific amount of a particular vinyl monomer containing hydroxy and sulfonate moiteies as an indispensable copolymerization component.
The present invention also relates to polymeric compositions specially acrylic resin compositions having excellent permanent antistatic properties and a method for the production thereof.
The instant invention also relates to novel ampholyte polymers, polymer compositions and methods for using such polymers and compositions in personal care applications. In general terms, the polymers and polymer compositions of the present invention are believed to be useful in the treatment of keratin-containing substrates. Keratin substrates include, but are not limited to, animal and human hair, skin and nails.
More particularly, the instant invention relates to polymer compositions and methods for treating keratin in which a cosmetically acceptable medium is used which contains at least about 0.01% by weight of an ampholyte polymer comprising acrylamidopropyltrimethyl ammonium chloride or methacrylamido-propyltrimethyl ammonium chloride; acrylic acid, methacrylic acid, 4-hydroxy-3-sulfonic acid-1-butene sodium salt and, optionally, an alkyl (meth)acrylate. Preferably, the cosmetically acceptable medium is a hair care product such as a shampoo, conditioner, styling product or rinse, or a skin care product such as a cleaner, lotion or cream.
In order to maintain the stability of aqueous polymer emulsions, it has been generally the practice heretofore in producing such emulsions to add a low molecular weight emulsifier upon polymerization or to compound a low molecular weight emulsifier or dispersant after polymerization. In recent years, there is an increasing demand in using aqueous polymer emulsions for paints, cement or mortar mixing, adhesives, textile treatment and paper processing. For such applications, the emulsion in intact form is usually used and not the polymer itself removed from the emulsion. Accordingly, when the emulsion contains an emulsifier or dispersant, foaming of the emulsion will occur on account of the emulsifier, etc. contained, and this makes it handling upon processing extremely difficult. Of course, the addition of a defoaming agent is attempted to prevent foaming, but when such an emulsion containing a defoaming agent is used for the above-mentioned purposes such as paint or cement, the mechanical strength or moisture-proofing of the film or shaped product will be seriously lowered by the secondary action of the emulsifier or defoaming agent, and this will constitute a great hindrance in practical use.
In order to obviate the defects attendant on such emulsifier-containing emulsions, aqueous emulsions free from low molecular weight emulsifiers have been noted in recent years, and many research investigations are being made of such emulsifier-free aqueous polymer emulsions or methods for producing the same.
Emulsifier-free aqueous polymer emulsions have various excellent features in comparison with the conventional emulsifier-containing emulsions. But on the other side, they involve a defect such that they are remarkably low in chemical stability, particularly in the stability against electrolytes, in comparison with the usual emulsifier-containing emulsions, and easily precipitate or coagulate by the addition of a small amount of electrolytes. Such defects present various problems and pose difficulties in practical use for applications wherein large amounts of electrolytes and other substances are mixed, as in paints, cement or mortar mixing, adhesives, paper processing and textile treatment.
Furthermore, in the emulsion (suspension) polymerization of ethylenically unsaturated monomers, :one or more surfactants (or emulsifiers) are employed conventionally to emulsify the monomer reactant(s) and the resulting polymer product latex. Such surfactants do not become chemically bonded to the polymer product molecule by carbon to carbon bonding (as distinct from a physical mixture, being absorbed on the polymer product or the like). It has been suggested that the small amount of surfactant which remains in the polymer product latex may interfere with performance of products, e.g., coatings and adhesives, prepared from such latex. U.S. Pat. No. 3,941,857 reports that coatings prepared from vinyl chloride/olefin copolymers show inconsistent performance in hot water resistance and tend to be sensitive to water in that pitting or xe2x80x9cblushingxe2x80x9d (a whitening effect) may sporadically occur, particularly after exposure of the coating to boiling water for extended periods. Such a performance characteristic is detrimental to certain end uses for such copolymers, e.g., container and paper coatings, interior and exterior coatings, industrial coatings, automotive coatings and certain adhesives.
Various proposals have been made for avoiding the reported adverse effects of surfactant residues in emulsion polymerized polymers. U.S. Pat. No. 3,941,857 describes incorporating a small amount of an epoxy resin with a vinyl chloride/olefin copolymer resin before casting a film from the resin. U.S. Pat. No. 4,049,608 describes the use of esters of an alkenoic acid selected from the group consisting of cinnamic acid and alkenoic acids of from 4 to 18 carbon atoms with a hydroxyalkane sulfonic acid in the emulsion polymerization of vinyl and other ethylenically unsaturated monomers. These esters serve the dual function of emulsifier and co-monomer. U.S. Pat. No. 4,224,455 describes a class of ringed sulfonated half esters of maleic anhydride and alkoxylated alkyl arylols. These esters are reported to be anionic emulsifiers (surfactants) and reactive functional monomers that are copolymerizable under emulsion polymerization conditions. U.S. Pat. No. 4,337,185 describes use of a reactive polymeric surfactant which is a substantially linear synthetic water-soluble surfactant whose polymeric backbone is derived from the polymerization of one or more ethylenically unsaturated monomers and which polymeric surfactant has a number average molecular weight of from about 500 to about 40,000 and contains various functional groups.
Also it is well known that acrylic resins have excellent gloss, transparency weatherability, excellent mechanical properties, and processability, and hence, are widely used for the preparation of advertising displays, lighting fixtures, covers, nameplates, and various decorations. However, because of their static properties, the acrylic resin products are easily charged by rubbing, etc. and the surface thereof is adhered with dust or rubbish, which results in deterioration of the beautiful appearance and in warping of the pointer of an instrument panel. There have been proposed various methods for imparting antistatic properties to the chargeable acrylic resin products. Such methods are roughly classified as follows: (1) a method of adding surfactants or fatty acid esters of a polyvalent alcohol to the acrylic resin; (2) a method of coating a silicon compound etc. onto the surface of the acrylic resin formed products and (3) a method of chemically modifying the resin structure by polymerizing the resin with a monomer having a hydrophilic group.
As the first method wherein a surfactant etc. is added thereto, there are proposed a method of using higher fatty acid monoglycerides (Japanese Patent Publication (unexamined) No. 112949/1978), and a method of adding an alkyldiethanolamine derivative (Japanese Patent Publication No. 21023/1978). According to this method, however, the surfactants etc. do not chemically bind to the acrylic resins, and hence, when the products are washed with water or rubbed, the products easily lose their antistatic properties. Besides, when a large amount of surfactants etc. are added thereto, the mechanical properties of the resin are deteriorated, and further, the surfactants etc. are easily bled to the surface thereof, by which the surface becomes sticky. Accordingly, the products are more easily adhered with dust or rubbish, which results in deterioration of the appearance.
It is also disclosed in Japanese Patent Publication (unexamined) No. 109944/1975 that a sulfonyl group-containing compound, a polyoxyalkylene glycol and a phosphite compound are admixed to the acrylic resin in order to impart antistatic properties thereto. However, only benzenesulfonic acid and toluenesulfonic acid are exemplified as the sulfonyl group-containing compound in this disclosures, and such sulfonic acids do not chemically bind to the acrylic resin and further show inferior compatibility with the acrylic resin. Hence, this method deteriorates the peculiar characteristics of the acrylic resin, i.e. surface gloss and transparency.
As the second method wherein a silicon compound is coated on the surface of the product, there is proposed, for example, a method of coating a solution of a partial hydrolysate of ethyl silicate onto the surface of the product (Japanese Patent Publication No. 6533/1956). This surface coating method is, effective for obtaining excellent antistatic properties which are durable, and thus, this method is practically used in some utilities. However, this method requires the steps of coating the antistatic agent onto the products and drying thereof, and therefore, this method has a problem with cost. This method also has drawbacks in that the coating film is easily broken by impact or rubbing to lose the antistatic properties.
As the third method wherein the structure of the resin per se is chemically modified, there is proposed, for example, a method of copolymerizing an acrylic monomer with a polyalkylene glycol monomethacrylate in order to improve the antistatic properties (Japanese Patent Publication (unexamined) No. 139516/1981). According to this method, a nonionic monomer is chemically bound to the resin, and hence, the undesirable dissolving out of the monomer is prevented, but the effect is not significant. Moreover, when a large amount of the nonionic monomer is incorporated, the resin exhibits reduced mechanical properties and lower heat resistance and the characteristics of the acrylic resin are significantly deteriorated. There is no method which can be employed practically.
Among the sulfonate-containing monomers which are known to exhibit antistatic properties, monomers which are hardly dissolved in methyl methacrylate, for example, sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, sodium alkenyl-aromatic sulfonate, or sodium methacryloxyalkylsulfonate, are not effectively used for the acrylic resin, because of their low compatibility with the resin, which causes a significant decrease in the characteristics of the acrylic resin, such as transparency, surface gloss, and as such, the products cannot practically be used.
The present inventor has carried out extensive studies on an improved acrylic resin composition which has excellent permanent antistatic properties without deteriorating the peculiar appearance of the acrylic resin. As a result, it has been found that a copolymer of an acrylic monomer and a small amount of the monomers of the present invention can be incorporated in order to give more enhanced properties, and further that the desired composition can be prepared by copolymerizing an acrylic monomer or a partial polymerizate thereof with the monomers of the present invention.
It is also well known that the surface properties of keratin are of interest in cosmetic science, and there has been a long-standing desire to discover ingredients which will beneficially affect the topical and bulk condition of keratinous substrates, such as hair. For example, such ingredients must have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property is referred to as xe2x80x9csubstantivityxe2x80x9d, i.e., the ability of a material to be adsorbed onto keratin and to resist removal by water rinse-off.
Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2-4.0. Therefore, at the pH of a typical shampoo, hair carries a net negative charge. Consequently, cationic polymers have long been used as conditioners in shampoo formulations, or as a separate treatment, in order to improve the wet and dry combability of the hair. The substantivity of the cationic polymers for negatively charged hair along with film formation facilitates detangling during wet hair combing and a reduction in static flyaway during dry hair combing. Cationic polymers generally also impart softness and suppleness to hair.
When cationic polymers are added to shampoos (or to skin care products such as cleaning compositions) containing anionic surfactants, formation of highly surface active association complexes generally takes place, which imparts improved foam stability to the shampoo. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic surfactant: cationic polymer, where the complex is least water soluble. Generally, cationic conditioners exhibit some incompatibility at these ratios. Compatibility gives a commercially more desirable clear formulation, while incompatibility leads to a haze or precipitation, which is aesthetically less desirable in some formulations.
Hair fixative properties such as curl retention are believed to be directly related to film forming properties of cationic polymers, as well as to molecular weight, with performance generally increasing with increasing molecular weight. However, the fixative properties conferred by cationic polymers generally tend to have a reciprocal relationship to other conditioning properties, i.e., good curl retention usually means that properties such as wet compatibility will suffer, and vice versa. Accordingly, there is a long felt need for polymers in the cosmetic field having hydroxy and sulfonate functionality such as the polymers described in the present invention.
The present invention provides a novel group of ethylenically unsaturated monomers containing hydroxy and sulfonate moieties that display surfactant activity, i.e., they function as surfactants (emulsifiers) in emulsion (suspension) polymerization processes. Moreover, they are copolymerizable with ethylenically unsaturated monomers, including vinyl monomers, of the type commonly employed in emulsion polymerization processes by virtue of the reactive double bond present in the compounds. In accordance with the present invention, there is provided a novel group of compounds having a hydrophobic portion containing ethylenic: unsaturation, and a hydrophilic portion containing a hydroxy group and a sulfonate group.
It is a first object of the present invention to provide novel polymerizable ethylenically unsaturated monomers having hydroxyl and sulfonate functionality.
It is another object of the instant invention to provide novel polymerizable ethylenically unsaturated monomers having hydroxyl and sulfonate functionality having properties as emulsifying agent and dispersing agents.
A further object of the invention is to provide a novel polymerizable emulsifying agents having hydroxyl and sulfonate moieties which are capable of preventing a discharge of an environmental pollutant such as emulsifying agent, water-soluble polymeric material, water-soluble oligomer or oil-soluble oligomer in an aqueous emulsion polymerization of xcex1, xcex2-ethylenically unsaturated monomer.
A still further object of the invention is to provide novel polymerizable emulsifying and dispersing agents which can give a polymer having improved properties such as transparency, heat stability, mechanical property, fastness to light, impact strength, heat flowability and processing property.
An additional object of the invention is to provide a novel process for emulsion-polymerizing xcex1, xcex2-ethylenically unsaturated monomer employing the specific polymerizable emulsifying agent.
Still further object of the invention is to provide an improved aqueous emulsion polymerization process for xcex1, xcex2-ethylenically unsaturated monomer which does not discharge an environmental pollutant such as emulsifying agent, water-soluble polymeric material, water-soluble oligomer or oil-soluble oligomer in a step such as filtration and washing of polymer.
An additional object of the present invention is a method of advantageously obtaining an emulsifier-free aqueous polymer emulsion having excellent chemical stability which has not been easily attained by the conventional emulsifier- or dispersant-free aqueous emulsions.
Another main object of the present invention is to provide an aqueous polymer emulsion having remarkably improved properties for use in paints, cement or mortar mixing, film formation, adhesives, textile treatment and paper processing.
Another object of the present invention is to provide an improvement in antistatic properties of polymeric resins derived from ethylenically unsaturated monomers, especially acrylic resin without deteriorating the peculiar characteristics of the acrylic resin, such as excellent appearance, surface gloss, mechanical properties, etc.
These and other objects of the invention will become apparent from the description hereinafter.
Briefly, the present invention is directed to water soluble ethylenically unsaturated monomers selected from the group consisting of formula I and II
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule.
The invention is also directed to a polymer comprising at least one repeating unit of a compound corresponding to formula (I) or (II):
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule and the polymer contains at least one additioner monomer.
The instant invention also relates to a cosmetically acceptable medium containing from about 0.1 to about 20%, based on the weight of said medium, of the above polymer.
The invention is also directed to an article of manufacture comprising a substrate coated on at least one side with an interpolymer comprising:
(a) a monomer having the formula (I) or (II):
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule;
(b) optionally one monomer selected from the group consisting of esters of acrylic acid and methacrylic acid containing from 6 to 20 carbon atoms, alone, or with
(c) optionally a monomer selected from the group consisting of alpha-olefins containing from 2 to 10 carbon atoms, vinyl esters of alkanoic acids containing from 3 to 10 carbon atoms, ethyl and methyl esters of acrylic and methacrylic acids, acrylonitrile, methacrylonitrile, styrene, vinyl toluene, and vinyl chloride, wherein the interpolymer has a weight average molecular weight in the range 10,000 to 1,000,000 and a glass transition temperature in the range of xe2x88x9215xc2x0 to xe2x88x9275xc2x0 C.
The invention is also directed to an ink comprising an aqueous medium, a water-insoluble colorant including a pigment, and a dispersant for dispersing said colorant in said aqueous medium, wherein said dispersant is a water-soluble polymer as described above. The inks which can form a recorded image have excellent fastness such as water resistance, light resistance, etc. and is also superior in storage stability and jetting stability.
The instant invention is further directed to a process for preparing acrylic polymers comprising aqueous-suspension polymerization carried out in the presence of 0.05-1% by weight, calculated on the suspension, of a stabilizer consisting of the polymer as described above.
The invention also features an ampholyte polymer comprising: (a) about 25 to about 75 mol % acrylamidopropyltrimethyl ammonium chloride or methacrylamido-propyltrimethyl ammonium chloride, alone or in combination; (b) about 25 to about 75 mol %-hydroxy-3-sulfonic acid-1-butene sodium salt, acrylic acid, methacrylic acid, alone or in combination; and (c) about 0.1 to about 20 mol % of a C1-C22 straight or branched chain alkyl acrylate or methacrylate.
The invention also relates to adhesive compositions as well as pressure sensitive adhesive formulations incorporating polymers derived from the monomers of the present invention.
In the first preferred embodiment, the present invention is directed to ethylenically unsaturated monomers corresponding to the following chemical structures I and II:
wherein R1, R2, R3, R4, R5 and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule. By stoichiometric valence requirement, applicant means the number of organic moieties having a negative charge required to satisfy the valence requirement of the positive metal atom. For example, if B is sodium x is 1, or if B is Zn x is 2.
The ethylenically unsaturated monomers of the present invention are made by reacting at a temperature range of about 45xc2x0 C. to about 70xc2x0 C., an epoxyalkene with sodium metabisulfite in water as a solvent and at a pH in the range of about 3.5 to 5.0, preferably at a pH in the range of about 4.0 to about 5.0, and more preferably at a pH in the range of about 4.5 to 5.0. A particularly preferred temperature range is about 55xc2x0 C. to about 65xc2x0 C. Typical epoxyalkenes that can be used as starting materials include epoxybutene (also known as vinyloxirane), 2-methyl epoxy 1-butene, epoxidized isoprene, 3,4-epoxy 1-pentene. More in particular, the starting epoxyalkenes are those corresponding to the formula
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen and C1-C5 primary, secondary or tertiary lower alkyl groups.
The reaction stoichiometry for the formation of the monomers of the present invention is illustrated below:
As shown above, the stoichiometry of the reaction is two moles of epoxyalkene and ONE mole of sodium metabisulfite in water to produce two moles of the hydroxy sulfonated alkene derivative.
In a second preferred embodiment, the invention is directed to both homopolymers of compounds of the formula I or II as well as copolymers having at least one repeating unit of compounds of formula I and II with other ethylenically unsaturated monomers. Among such other known polymerizable ethylenically unsaturated compounds are the alkenyl-aromatic compounds, i.e., styrene and o-, m-, and p-vinylstyrene, the derivatives of xcex1,xcex2-ethylenically unsaturated. acids such as the esters, amides, and nitriles of acrylic acid, methacrylic acid, itaconic acid, and maleic acid, unsaturated alcohol esters, unsaturated ketones, unsaturated ethers, and other compounds containing one or more ethylenic linkages, especially those having a single unsaturated group of the formula H2Cxe2x95x90Cxe2x80x94, capable of addition polymerization. Specific examples of such ethylenically unsaturated compounds are styrene, xcex1-methylstyrene, methylstyrene, ethylstyrene, xcex1, xcex1 dimethylstyrene, dimethylstyrene, vinylnaphthalene, hydroxystyrene, methoxystyrene, cyanostyrene, acetylstyrene, monochlorostyrene, dichlorostyrene and other halostyrenes, methyl methacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, lauryl methacrylate, phenyl acrylate, acrylonitrile, methacrylonitrile, acrylanilide, acrylamide, N-methylolacrylamide, ethyl .alpha.-chloroacrylate, ethyl maleate, polyglycol maleate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide, vinyl methyl ketone, isopropenyl ketone, vinyl ethyl ether, and dienes which generally act as though they have only one point of unsaturation during normal polymerization, such as 1,3-butadiene, isoprene, and the like.
The monomers of formula I and II and their water-soluble salts may be homopolymerized in bulk or in an aqueous solution thereof using a suitable polymerization catalyst or initiator or an initiator system, such as a redox system. The catalyst or initiator may simply be radiation, especially ultra-violet light, or it may be a free radical type of initiator, miscible with the monomer or soluble in the aqueous medium. Examples include hydrogen peroxide, ammonium or an alkali metal (e.g. sodium or potassium) persulfate, t-butyl hydroperoxide, cumene hydroperoxide or azo-bisisobutyronitrile. Such initiators may be used in the customary amounts of about 0.1 to 3% by weight based on total monomer weight. In redox systems, a free radical initiator, such as the type mentioned is used with a reducing agent, such as sodium hydrosulfite, potassium inetabisulfite, or ascorbic acid, in comparable amounts, e.g. 0.1 to 3% based on monomer weight. Any suitable pH may be maintained such as in the range from 3 to 10, an acid, base, and/or buffering agent or agents being included as desired.
Homopolymers and copolymers can also be produced in any other solvent medium, such as an ester, e.g. ethyl acetate, a ketone, e.g., acetone or methyl isobutyl ketone, an ether, e.g. dioxane, and the dimethyl ether of diethylene glycol, or mixtures containing two or more such solvents or containing water and one or more of the organic solvents just mentioned. Alcohols are unsuitable for use as the solvent medium whenever complex ester product mixtures are to be avoided. An initiator or initiator system that is soluble in the medium may be used, such as any of those mentioned above for use in the aqueous systems.
Copolymers of one or more other monomers, such as those previously mentioned, with a monomer of formula I and II can be produced efficiently in an aqueous medium, with and more particularly without the use of an emulsifying agent to aid in the dispersion of any water-insoluble monomer. When an emulsifier is used, it may be used in conventional amount in the range of 0.05 to 6% or more based on the weight of water-insoluble monomer used in the polymerization process. The water-soluble initiator or initiator systems mentioned above may be used in the amounts stated. Generally, the polymers produced have high molecular weight, such as from about one million to ten millions or more. However, a chain transfer agent, such as bromotrichloroethane, methylene chloride, a (C2-C12)alkyl mercaptan, e.g. dodecyl mercaptan, or a hydroxyalkyl mercaptan, e.g. xcex2-hydroxyethyl mercaptan, may be used to obtain polymers of lower molecular weights, such as from about 10,000 to any point below that which the system in use normally produces without such an agent, the more of the agent used, the lower the molecular weight for any particular chain transfer agent. The amount of such an agent used may be from about 0.05% to 10% or more based on the total monomer weight.
A suspension polymerization technique of normal type employing a colloid, such as polyacrylic acid or poly(xcex1-vinylpyrrolidinone), may be used to form copolymers containing a large proportion of at least one monomer of formula I and/or II cross-linked by about to 5 to 50% (preferably 15 to 35%) by weight of a diethylenically unsaturated copolymerizable monomer such as divinyl benzene, ethylene glycol dimethacrylate, or diallyl phthalate. Such polymers are obtained in the form of beads or granules which are useful as cation-exchange resins.
The monomers of formula I and II as well as the homopolymers of a monomer of formula I and II herein and copolymers formed largely (at least 55% by weight) of one or more monomers of formula I and II and containing 0% to 45% by weight of other monomers of the types mentioned hereinabove are useful as surfactants, such as wetting agents, as antistatic agents for textiles and other articles formed of hydrophobic materials such as nylon, cellulose esters, and polyesters and as softening agents for textiles, such as cotton and rayon. They are also useful as conductivity aids in paper, such as that used in electrostatic reproduction. They are also useful to stabilize aqueous polymer dispersions and water-base paints against coagulation as a result of freezing and subsequent thawing. They, and especially the polymers, are useful as flocculating agents. To serve these purposes, the amount of the monomer or polymer needed is quite small relative to the magnitude of the system to which or in which they are applied. When a relatively small amount of a monomer of formula I and/or II is incorporated as a polymerized component in water-insoluble polymers used in the coatings industry, the copolymers that are obtained show remarkable improvements in adhesion to various substrates, and especially those of, or carrying a deposit of, a plastic or resinous material.
The polymers contemplated here are the addition polymers of at least one monoethylenically unsaturated monomer having a group of the formula H2Cxe2x95x90Cxe2x80x94, including a vinyl ester of a (C1-C18)alkanoic acid, e.g. vinyl acetate, vinyl versatate, and vinyl dodecanoate; a (C1-C18)alkyl ester of acrylic acid or methacrylic acid, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate or methacrylate; a vinyl-aromatic hydrocarbon, such as styrene and vinyltoluene; acrylonitrile, acrylamide and so forth.
Thus the copolymers containing from as little as 0.1% by weight, based on copolymer weight, up to 2% or 5% by weight of a monomer of formula I and/or II are exceptionally useful for improving the adhesion of coatings of compositions comprising such copolymers when applied to substrates of metal, glass, or plastic carrying a deposit of a vic-epoxy resin primer, an aminoplast resin primer, or primers formed of mixtures of such resin-forming substances, all of which are of commercial types commonly available on the market.
Copolymers of monoethylenically unsaturated compounds containing small amounts of a monomer of formula I and/or II such as from about 0.2% to 5% or even up to 10% are useful to impart antistatic properties to textiles and other materials formed of hydrophobic materials, such as nylon, cellulose esters including cellulose acetate and cellulose acetate butyrate, and polymers such as the condensates of ethylene glycol with terephthalic acid. Preferably, such copolymers are prepared by emulsion polymerization processes so that a latex or aqueous dispersion of the polymer is produced containing anywhere from 20 to 60% by weight of the polymer dispersed herein. In applying the dispersion to the fabric or other material the dispersion may be diluted to bout 15 to 30% solids and applied by spraying, use of a textile pad, or brushing as is most suitable for application to the particular substrate involved. Effective antistatic properties are obtained by the application of an amount from about 0.1 to 14% by weight of the polymer based on the weight of fibers in the case of the textile material whereas effective antistatic property is obtained by the application of such a polymer on a solid article such as a molded plastic article when the polymer is deposited in the form of a thin film of about 1-10 microns thickness.
In a third preferred embodiment, the polymerizable anionic emulsifying agent of the invention is added into an emulsion polymerization system to make emulsion polymerization proceed the same as in a normal nonpolymerizable emulsifying agent. The polymerizable anionic emulsifying agent per se is also copolymerized with other monomers and chemically bonded within a polymer molecule. Then, the residual amount of the emulsifying agent is infinitesimal when the polymerization terminates. Therefore, it is possible to minimize the discharge of environmental pollutants which are discharged together with industrial wastes at the time of separating the polymer from latex through salting-out, filtration and washing.
In order to exhibit the effect of preventing discharge of environmental pollutants most effectively, it is necessary to employ the present polymerizable anionic emulsifying agent according to the following means. That is to say, 93 to 99.5% by weight of xcex1, xcex2-ethylenically unsaturated monomer having solubility of not more than 10% by weight to water at 35xc2x0 C. and 0 to 2% by weight of xcex1, xcex2-ethylenically unsaturated monomer having a solubility of more than 10% by weight to water at 35xc2x0 C. must be copolymerized in the presence of 0.5 to 5% by weight of the present polymerizable anionic emulsifying agent in an aqueous medium.
The polymerizable anionic emulsifying agent in the invention has the similar emulsifying function to a conventional anionic emulsifying agent. The emulsifying agent forms micelle in the aqueous medium by which the monomer is solubilized and the resultant polymer particles are protected by chemically bonding so that a stable polymer dispersion is provided.
One of the principal advantages of the hydroxyl and sulfonate substituted alkenes of the present invention is that enviromental pollution due to the drainage can be prevented by the employment of the present polymerizable anionic emulsifying agent under specific conditions. Since the hydroxyl and sulfonate substituted alkenes of the invention adequately copolymerize with xcex1, xcex2-ethylenically unsaturated monomer, the water-soluble copolymerized material being abundant in the emulsifying agent, the emulsifying agent is chemically bonded to the polymer in high quantities. Therefore, the emulsifying agent employed in the polymerization is scarcely discharged into the drainage as an unreacted emulsifying agent, a water-soluble polymeric material or a homopolymer when the polymer is recovered from the polymer dispersion through salting out, filtration and washing.
Another principal advantage of the present invention is that the deterioration of quality of a shaped article prepared therefrom can be prevented. In case of manufacturing shaped articles such as film, fiber, or the like, from the polymer prepared by employing a conventional emulsifying agent, the obtained shaped article is inferior in transparency, heat stability, mechanical property, fastness to light, chemical resistance or water resistance since the employed emulsifying agent remains in the polymer with it being adsorbed even if water washing of the polymer is carried out with large amounts of water. However, according to the present invention, the polymerizable anionic emulsifying agent is chemically bonded within the polymer molecule obtained by the copolymerization since the emulsifying agent can adequately copolymerize with the xcex1, xcex2-ethylenically unsaturated monomer.
In another embodiment of the present invention, particularly for producing the emulsifier-free aqueous polymer emulsion of the present invention is that the amount of use of the monomer represented by the general formula (I) or (II) should be within the range of 0.01 to 30 weight % based on the total monomer mixture to be copolymerized. When the amount of use is less than 0.01 weight %, the chemical stability, the attainment of which is an object of the present invention, cannot be obtained, and on the other hand when it exceeds 30 weight %, the physical properties of the film formed from the emulsion, especially the mechanical strength and water resistance, will seriously lowered, and the film cannot be submitted to practical use. In order to bring the chemical stability of the emulsion and the physical properties of the film produced therefrom within a more preferred range in practical use, it is preferable to maintain the amount of use of the monomer represented by the general formula (I) or (II) within the range of from 0.5 to 10 weight %.
When making acrylic resins copolymerized with the monomers of the present invention, the polymerization reaction may also be done by first partially polymerizing the starting acrylic monomer comprising predominantly methyl methacrylate to give a partial polymerizate (in the form of a syrup) and adding thereto a monomer of formula I or II and other ingredients and then continuing the polymerization reaction.
Among the conventional polymerization methods as mentioned above, bulk polymerization is particularly suitable in view of its easy operation. According to so-called xe2x80x9ccasting polymerizationxe2x80x9d, the desired antistatic acrylic resin cast plate can easily be prepared.
The casting polymerization is usually carried out as follows. To the starting acrylic monomer, i.e. methyl methacrylate alone, or a monomer comprising predominantly methyl methacrylate, or a partial polymerizate thereof (in the form of a syrup), are added a monomer of formula I or II, and other additives, and the mixture is mixed well to give a uniform solution. The solution pe se or after partially polymerizing into the form of a syrup, is admixed with a radical polymerization initiator to give a casting material. The casting material thus prepared is poured between two reinforced glasses which are set face to face, with a space, the periphery thereof being sealed with a gasket, and then subjected to a polymerization reaction with heating. This method is known as xe2x80x9cglass cell castingxe2x80x9d.
Alternatively, the casting material is continuously poured into the space between two metallic endless belts which are run in one direction at a constant speed, one surface of the metallic belt being planished and the periphery of the belts being sealed with a gasket, and then subjected to a polymerization reaction with heating. This method is called xe2x80x9ccontinuous castingxe2x80x9d. In the present invention, both the glass cell casting and the continuous casting are effectively used.
The methacrylic resin thus obtained has excellent antistatic properties without deteriorating the natural properties of the methacrylic resin, such as transparency, surface gloss, mechanical properties, weatherability, and processability. Moreover, the excellent antistatic properties are changed neither by washing with water nor rubbing, nor with a lapse of time. Thus, the methacrylic resin obtained by the present invention is practically very useful.
As used in this specification the term emulsifier-free aqueous polymer emulsion means those produced without addition of any low molecular weight emulsifier before, during or after polymerization.
In a further embodiment of the invention, the Applicant has also found a process for preparing acrylic polymers in suspension which utilizes, as a suspending agent, a polymeric product which imparts high stability to the suspension, allows to obtain beads endowed with a regular morphology and free from agglomerates, even operating with water/monomer ratios very close to the unit, reduces the fouling of the polymerization reactors, lowers the concentration of the polymer in emulsion in the waste waters to extremely low values and, in the case of polymethylmethacrylate (PMMA), imparts a high optical purity to the product.
The process for preparing acrylic polymers by aqueous suspension polymerization is conducted in the presence of 0.05-1% by weight, calculated on the suspension, of a stabilizer consisting of a polymer obtained by polymerization of: 60-100% by weight of a salt of a monomer having general formula:
wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule; and 0-40% by weight of at least an acrylic monomer. Typically, B represents an alkaline metal or an alkaline-earth metal such as, for example, sodium, potassium, calcium, magnesium, etc.
The new monomers of the present invention are typically copolymerized in aqueous emulsion and the resulting copolymers have improved physical properties such as polymer modulus, solubility, conductivity, and electrostatic properties. Also, the new monomers provide improved water solubility and more in particular they provide self-dispersing properties to the resulting polymers i.e., the resulting polymers don""t require additional emulsifiers or dispersing agents. Additionally, the monomers of the instant invention allow the polymer chemist to prepare high solid emulsions because of the stabilizing effect of the monomer containing both hydroxyl and sulfonate moieties.
The resulting copolymers containing varying amounts of the monomer of the present invention also improves the adhesion properties of the resulting polymer to a wide variety of surfaces i.e., organic and inorganic surfaces, they can also be used as thickeners, and they also provide films having improved film strength.
Another use of the resulting copolymers of the invention, is in promoting conductivity and electrostatic charge dissipation. Further uses of the resulting copolymers include wetting of films to facilitate subsequent coating applications such as inks, paints and adhesives.
Other applications wherein the copolymers of the present invention are useful include promotion of high gloss of the resulting films, soil release, stain release, textile wetting applications and antiredeposition in laundering applications.
Applicant""s have also found that ampholyte polymers, which comprise: a) acrylamidopropyltrimethyl ammonium chloride or methacrylamidopropyltrimethyl ammonium chloride; b) acrylic acid (AA), methacrylic acid (MM), 4-hydroxy-3-sulfonic acid-1-butene sodium salt and c) optionally, a C1-C22 straight or branched alkyl acrylate or methacrylate; are generally useful in cosmetic formulations and provide particularly improved conditioning properties to hair products. Aside from improved conditioning, as measured by combability, substantivity, flyaway and/or feel, these polymers at the same time may improve, but are generally not detrimental to, hair fixative properties such as curl retention.
In a further preferred embodiment of the present invention, an effective amount of an ampholyte polymer described above is added to an anionic surfactant-containing hair or skin care product, preferably a hair care product. Thus, the polymer compositions of the present invention can be used in, inter alia, shampoos, conditioners, rinses, coloring products, bleaching products, setting lotions, blow-drying lotions, restructuring lotions, perms and straightening products.
Aside from hair care uses, skin and nail conditioning products are desired which function to improve properties such as retention of moisture, softening of the skin, attraction of air moisture, retardation of water loss, feel and reduction of skin irritations caused by contact with cosmetic ingredients. Examples of such products include detergents, lotions and soaps.
The present invention is illustrated by the following Examples, but should not be construed to be limited thereto. In the Examples, xe2x80x9cpartxe2x80x9d and xe2x80x9c%xe2x80x9d are all part by weight or % by weight unless specified otherwise.

Hydroxy and sulfonic acid substituted alkenes and salts

Abstract: wherein R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, and C1-C5 primary, secondary or tertiary lower alkyl group; B is a monovalent or multivalent metal selected from the group consisting of alkali metals, alkaline earth metals and transition metals; and x represents the stoichiometric valence requirement of the molecule. The invention also provides polymers and emulsions derived from the above monomers.


In order to improve the manufacturing yield of a semiconductor device having a three-dimensional structure in which a plurality of chips are stacked and attached to each other, the opening shape of each of conductive grooves (4A) formed in each chip (C2) obtained from a wafer (W2) is rectangular, and the number of the conductive grooves (4A) whose long-sides are directed in a Y direction and the number of the conductive grooves (4A) whose long-sides are directed in an X direction perpendicular to the Y direction are made to be approximately equal to each other number in the entire wafer (W2), whereby the film stress upon embedding of a conductive film into the interior of the conductive grooves is reduced, and generation of exfoliation and micro-cracks in the conductive film or warpage and cracks of the wafer (W2) are prevented.

A semiconductor device having a three-dimensional structure has attracted interest as an effective structure which avoids various obstacles with which a semiconductor device having a two-dimensional structure confronts, such as limits of lithography techniques, tendency of the operation speed to be saturated by increase in wiring resistance and parasitic effects, and high electrical field effects by miniaturization in element dimensions, and keeps improving the integration level, by integrating three-dimensionally semiconductor elements in a stacked multi-layer structure, by stacking semiconductor active layers.
Semiconductor devices having three-dimensional structures are described, for example, in Japanese Patent Application Laid-Open Publication No. H11-261000 (Patent Document 1) and Japanese Patent Application Laid-Open Publication No. 2002-334967 (Patent Document 2), and also methods of manufacturing semiconductor devices having three-dimensional structures by mutually attaching semiconductor substrates in which semiconductor elements are formed are disclosed. These documents also disclose structures in which through-electrodes called vertical mutual connection bodies or embedded connection electrodes are formed in grooves penetrating from the main surfaces to the rear surfaces of desired semiconductor substrates so that the main surfaces and the rear surfaces of the semiconductor substrates are electrically conductive each other.
FIG. 15 of "Denso Technical Review Vol. 6 No. 2 2001" (Non-Patent Document 1) discloses techniques of embedding copper (Cu) in connection holes of a semiconductor device having a three-dimensional structure by a plating method.    Patent Document 1: Japanese Patent Application Laid-Open Publication No. H11-261000    Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2002-334967    Non-Patent Document: "Denso Technical Review Vol. 6 No. 2 2001" (FIG. 15)


Disclosed is fiber-reinforced thermoplastic resin pellets that satisfy the quality stability (homogeneous impregnation, deterioration prevention of reinforcing fiber) of the molding material and the strength performance of the molded product, using natural discontinuous fiber as the reinforcing fiber, and a manufacturing method of the pellets. A plurality of spun yarns with No. 5 to 80 counts are twisted 10 to 200 turns/m and pultruded when fiber-reinforced thermoplastic pellets containing natural fiber as the reinforcing fiber are manufactured by the impregnating pultrusion method.

1. Field of the Invention
The present invention relates to fiber-reinforced thermoplastic resin pellets that use natural discontinuous fiber as reinforcing fiber and a manufacturing method thereof. Furthermore, the present invention relates to the automobile parts manufactured using the pellets.
2. Description of the Related Art
Recently, fiber-reinforced resin in which vegetable fibers such as wood pulp, hemp, and hemp palm are used as reinforcing fiber has been actively developed. Nowadays, awareness of waste pollution has been increasing. The reason for this will be described hereinafter. Natural fiber does not cause waste pollution even if it is used for land filling as it is an environment-friendly material. In addition, when natural fiber is burnt, it generates a great deal of combustion energy allowing high energy recovery without causing secondary pollution such as residual ash or flue gas pollution.
However, natural fiber is a discontinuous fiber differing from continuous fibers such as glass fiber, carbon fiber, metal fiber, and various synthetic fibers that have conventionally been used as reinforcing fibers for fiber reinforced-resin. Therefore, a special technique is required to manufacture molding resin pellets mixed with natural fiber that exhibit the characteristics of long fiber. For example, a continuous fiber strand is impregnated in a molten resin bath continuously and pultruded, and cooled to solidify the resin and then cut into pellets of an arbitrary length. This method is widely used to manufacture fiber-reinforced resin pellets continuously with high productivity. However, even if discontinuous natural fibers are twisted into yarns, the strength of the spun yarns is insufficient to be processed in a molten resin bath, discontinuous fiber spun yarns are often broken due to the release of discontinuous fiber in the resin bath when the spun yarns are impregnated and pultruded in the molten resin bath. This makes it difficult to continue stable operation.
For example, methods for manufacturing fiber-reinforced resin pellets using discontinuous natural fiber as a reinforcing fiber described are proposed hereinafter, but the methods have both merits and demerits.
(1) A method in which natural fiber is kneaded to mix it homogeneously in molten thermoplastic resin using a roll kneader and then the mixture is cooled to solidify, and the product is crushed to form resin pellets (J-P-A No. 108161/1982). By applying this method, molding material in which discontinuous fiber is dispersed homogeneously in matrix resin is obtained. However, the molding material has disadvantages in that the handling process, including the molding process, is difficult and quality stability of the molded product is poor due to irregularity in the size of the resin pellet.
(2) A method in which discontinuous fiber is spun to form spun yarn, spun yarn is processed to form fabrics or wovens, nonwovens, or mats, the processed product is impregnated in a molten resin bath and then cooled to solidify, and the cooled product is cut into the product of a suitable configuration and size to form resin pellets. (J-P-A Nos. 28307/1983, 7307/1991, 30916/1991, and 41280/1997). This method is suitable for applications in which the product is used for secondary molded material such as a resin-impregnated sheet, but when the product is used in the form of a pellet, the product that has been cooled and solidified is cut into pellets of a suitable configuration and size, and the cutting process requires much working and results in a low productivity. Furthermore, the cutting process is involved in a problem of much loss, and dust generated in cutting process causes pollution of the working environment.
(3) A method in which molten resin and discontinuous fiber are kneaded using a kneader or a kneading extruder and then the molten mixture is extruded, cooled, and solidified to form a rod product, afterwards, the rod product is cut into pellets of an arbitrary length (J-P-A Nos. 146945/1987, 146947/1987, and 290453/1991). This method has disadvantages in that it is difficult to feed cotton-like fiber into a kneading extruder, and the reinforcing fiber is subjected to thermal deterioration when resin is heated for melt kneading, and reinforcing fiber is subjected to mechanical damage due to the kneading force. As a result, the reinforcing effect is poor. In particular, because heat decomposition usually begins at a temperature range of 150 to 180xc2x0 C. in the case of vegetable fibers such as wood pulp and linen, thermoplastic resin that does not cause such problems must be selected for composite forming depending on the fiber type and kneading time. Therefore, the freedom in selection of matrix resin is limited. Furthermore, because such resin with a low melting point is generally not strong, the application of the fiber-reinforced resin molded product is naturally limited.
(4) A method in which composite fiber strands comprising reinforcing spun yarn and thermoplastic resin fiber is formed, and the composite fiber strand is heated to melt the thermoplastic resin fiber, it is cooled and solidified, and then the solidified product is cut into pellets of a suitable length (J-P-A No. 163002/1992). To apply this method, thermoplastic resin fiber is manufactured previously or mixed yarn containing reinforcing fiber and thermoplastic resin fiber is manufactured, the manufacturing process requires a lot of work, and this method is troublesome. Furthermore, insufficient impregnation can occur causing void defects depending on the heat melting conditions for melting the thermoplastic resin fiber.
(5) A method in which a reinforcing fiber strand is impregnated with molten thermoplastic resin, cooled and solidified, and then cut into pellets of a suitable length (for example, J-P-B Nos. 37694/1988, 57407/1994 and J-P-A Nos. 178411/1989, 119807/1992). This literature disclose a case where jute (linen fiber) can be used as a reinforcing fiber, however, they mainly disclose cases where continuous fiber is used as a reinforcing fiber. This literature does not reveal any detailed problem arising when discontinuous fiber is mixed with thermoplastic resin as a reinforcing fiber to form composite material.
The inventors of the present invention are interested in a natural discontinuous fiber that has attracted much attention as a reinforcing fiber in the above-mentioned known circumstances, and have developed a technique for manufacturing discontinuous fiber reinforced thermoplastic resin pellets that solve problems of conventional resin pellets as described hereinbefore caused in the manufacturing process of molding thermoplastic resin pellets consisting of a composite material containing reinforcing fiber in thermoplastic resin. Particularly, all the problems in the continuous manufacturing process, in quality stability (homogeneous impregnation and prevention of reinforcing fiber), and in the strength characteristic of the molded product are to be solved.
Accordingly, it is an object of the present invention to provide discontinuous fiber reinforced thermoplastic resin pellets that satisfy the conditions required for continuous production, quality stability of the molded material (homogeneous impregnation and deterioration prevention of reinforcing fiber), and the strength characteristics of the molded product.
It is a further object of the present invention to provide natural fiber-reinforced thermoplastic resin pellets comprising thermoplastic resin and strand comprising a plurality of spun yarns of natural fiber twisted in a range from 10 to 200 turns/m, wherein the spun yarn is No. 5 to 80 counts in diameter.
It is yet another object of the present invention to provide a method for manufacturing natural fiber-reinforced thermoplastic resin pellets comprising the steps of: an impregnating step for impregnating in a thermoplastic resin bath, a plurality of spun yarns of natural fiber being No. 5 to 80 counts in diameter, a pultruding step for pultruding the spun yarns with twisting 10 to 200 turns/m to obtain natural fiber-reinforced thermoplastic, and a pelletizing step for pelletizing the natural fiber-reinforced thermoplastic resin.
It is still another object of the present invention to provide natural fiber-reinforced thermoplastic resin-made automobile parts manufactured using natural fiber-reinforced thermoplastic resin pellets as the molding material.
Other objects and advantages of the present invention will become apparent from the detailed description to follow taken in conjunction with the appended claims.
As described hereinbefore, in the present invention, molten thermoplastic resin is impregnated in discontinuous natural fiber and the impregnated fiber is pultruded, and then cut into fiber-reinforced thermoplastic resin pellets of a suitable length. In the manufacturing process, the spun yarn that is formed by twisting natural fiber properly is used wherein the yarn number count of the spun yarn is specified, a plurality of spun yarns are paralleled to form a paralleled yarn, the paralleled yarn is twisted properly and impregnated with thermoplastic resin, the impregnated yarn is pultruded and cooled and solidified, and then it is cut into fiber-reinforced resin pellets of a suitable length. By employing this method, long fiber-reinforced thermoplastic resin pellets in which discontinuous natural fiber is used as a reinforcing fiber is manufactured continuously with high productivity.
The fiber-reinforced thermoplastic resin pellets of the present invention obtained by this method are characteristic based on the feature of the manufacturing process described hereinbefore in that a plurality of discontinuous fiber spun yarns that have been twisted properly is embedded in thermoplastic resin.
Examples of natural fiber used in the present invention include flax, ramie, abaca, sisal, jute, hemp, kenaf, Boehmeria nipponivea fiber or Japanese ramie, coir, cotton, kapok, hemp palm, rice straw, wheat straw, pineapple fiber, wool, and silk. These fibers are used alone individually, or a plurality of these fibers are used in combination as required. When a plurality of natural fibers are used combinedly, blended yarn that is formed by blending fibers in a spinning process may be used or a blended strand that is formed by blending different spun yarns in a paralleling process may be used. Furthermore, it is possible to combine a plurality of types of spun yarns when thermoplastic resin is impregnated in a plurality of spun yarns (bundle) to form a composite. Furthermore, it is possible to mix a small amount of discontinuous synthetic fiber with natural fiber depending on the case.
The thickness of spun yarn to be used is preferably of a No. 5 to 80 count (spun yarn with a weight of 1 kg and a length of 29,029 m is a No. 1 count) represented by a jute yarn number count according to JIS L0101 (based on a given length), thin spun yarn is preferably used from the view point of good penetration of thermoplastic resin, and a No. 7 to 80 count, or preferably a No. 10 to 40 count is used.
If thin yarn thinner than a No. 5 count is used, the strength of the single yarn is too weak to withstand the drawing force, the yarn can be broken due to drawing tension thus causing difficulty in stable continuous manufacturing. On the other hand, If yarn thicker than a No. 80 count is used, impregnation of resin is insufficient, and when the impregnated strand is cut using a pelletizer, the fluffing caused results in a polluted working environment, or a bridging of pellets occurs due to fluff at the hopper, thus resulting in poor productivity of the molded product and insufficient mechanical properties of the molded product when the obtained resin pellet is used.
Next, the detailed manufacturing method will be described hereinafter. Natural discontinuous fiber is twisted to form a spun yarn, a plurality of spun yarns are paralleled, the paralleled yarns are passed through a molten thermoplastic resin bath where thermoplastic resin extruded from an extruder is filled. The plurality of spun yarns is twisted in the molten thermoplastic resin bath to form a strand. In the molten thermoplastic resin bath, the molten thermoplastic resin is impregnated into the spun yarn strand. The spun yarn strand impregnated with thermoplastic resin is pultruded through a nozzle and cooled, and it is cut to form fiber-reinforced thermoplastic resin pellets containing a natural discontinuous fiber of a certain length.
At that time, it is preferable to control the impregnating duration from the time when the spun yarn strand enters the molten thermoplastic resin bath to the time when it is pultruded through the nozzle to be less than 10 seconds, or preferably less than 5 second. If the impregnating duration is excessively long, the duration while the natural fiber is being subjected to heat in the molten thermoplastic resin bath is also too long, and heat deterioration of the fiber can be caused. On the other hand, if the impregnating duration is excessively short, the impregnation is not sufficient. The time is preferably equal to 0.1 seconds or longer, or better still equal to 0.15 seconds or longer.
During the process in which the spun yarn strand is impregnated in the bath, passed through the bath, and pultruded from the bath, the paralleled spun yarns are twisted with a pitch of 10 to 200 turns/m, preferably 15 to 150 turns/m, or better still 20 to 120 turns/m. The molten thermoplastic resin penetrates into the spun yarn strand due to proper twisting, and the proper twisting brings about good impregnation. Even if some spun yarns are partially loosened to result in released yarn, such yarns are twisted together with other spun yarns to form a strand. Therefore, the spun yarn strand will not be broken in the impregnating bath, and is pultruded stably to form a resin-impregnated continuous strand. The continuous manufacturing process will not suffer from stoppage problems.
Spun yarns may be Z twist yarns or S twist yarns, but usually Z twist yarns are employed. In the present invention, for example, when Z twist yarns are used, it is preferable that the paralleled Z twist yarns are S-twisted in the molten thermoplastic resin bath, because Z twist yarns are untwisted slightly during the impregnating process and the molten resin penetrates easily into the spun yarn strand. However, when spun yarns of a small yarn number count are used, because the untwisting of the spun yarn can result in insufficient strength, it is preferable that paralleled Z twist yarns are Z-twisted to secure sufficient strength. Based on the above, it is desirable that Z-twisting is employed for spun yarns with No. 5 to 20 counts to supplement the insufficient strength, and on the other hand S-twisting is employed for spun yarns with No. 21 to 80 counts to improve penetration.
The impregnated strand is cooled downstream after pultruding to solidify the impregnated thermoplastic resin, and then cut to form fiber-reinforced resin pellets containing discontinuous natural fiber of a suitable length. The fiber-reinforced resin pellets obtained as described hereinbefore contains natural fiber spun yarn and a twisted strand comprising a plurality of spun yarns in a solidified matrix thermoplastic resin because of the characteristics of the manufacturing method. Such a distribution of natural fibers in pellets is different from that of reinforcing fiber in known continuous long fiber-reinforced resin pellets and in another type of fiber-reinforced resin pellet that is formed by a method in which woven or knitted fabric formed using discontinuous fiber spun yarn is impregnated with resin and then cut to form resin pellets.
In the fiber-reinforced resin pellets of the present invention, discontinuous natural fiber is doubly twisted resultantly in the resin. Therefore, the length of natural fiber contained in a pellet is slightly longer because of the double twisting with respect to the pellet length. Therefore, it is possible to handle pellets containing longer natural fiber as a reinforcing material advantageously (usually, long pellets cause bridging at a hopper in the molding process).
If the number of twistings in the above-mentioned impregnating and drawing process is less than 10 turns/m, the improvement in tensile strength due to twisting is insufficient, short fiber is released from spun yarn and mixed in the molten resin bath to cause increased drawing resistance and break of the natural fiber spun yarn strand. On the other hand, if the number of twistings is as excessive as 200 turns/m, the penetration of resin into the spun yarn strand is insufficient and results in a poor quality of fiber-reinforced resin pellets and a poor property of the molded product.
The type of thermoplastic resin used as the matrix resin in the present invention is not limited particularly, and any thermoplastic resin can be used. For example, polyolefin resin such as polypropylene (PP), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE); polyamide resin such as polyamide 4, polyamide 6, polyamide 66, polyamide 6, polyamide 10, polyamide 11, polyamide 12, and aromatic polyamide; polyester resin such as polyethylene-terephthalate (PET) and polybutylene-terephthalate (PBT); polycarbonate resin; polystyrene resin; acrylic resin; AS resin; ABS resin; PPS resin; POM resin may be used in the form of homopolymers or copolymers, or in the form of blend polymers containing two or more polymers. The thermoplastic resin to be used may be arbitrarily selected in consideration of the required property of the fiber-reinforced resin molded product to be obtained as the final product.
However, because, in the present invention in which natural fiber is used as a reinforcing fiber, natural fiber is decomposed and deteriorated thermally resulting in a damaged reinforcing function of the material when natural fiber is exposed to a high temperature during molding, it is preferable to use thermoplastic resin with a melting or softening temperature less than 220xc2x0 C., more preferably less than 220xc2x0 C., and further preferably less than 180xc2x0 C.
Among the above-mentioned thermoplastic resins, polyolefin resin such as polypropylene (PP), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polymer of xcex1-olefin such as butene-1, hexene-1, and octane-1 or a copolymer of these olefins, modified polyolefin resin modified with unsaturated carboxylic acid or derivatives thereof; ethylene-vinylacetate resin (EVA); or blend resins containing two or more polymers described hereinbefore may be used in view of the balance between the product property and cost.
Examples of the above-mentioned unsaturated carboxylic acid or derivatives thereof used for modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, esters of these acids, maleic anhydride, and itaconic anhydride. Among these substances, it is preferable to use maleic anhydride and glycidyl methacrylate.
Various modified resins that are compatible with natural fibers and thermoplastic resin may be added to thermoplastic resin to improve the adhesion to the natural fiber. Effective examples of modified resin include, for example, polyolefin modified with maleic anhydride, polyolefin modified with oxazoline, and polyolefin modified with glycidyl methacrylate for polyolefin resin. The property of the molded product can be further improved by adding an adequate amount of these substances. The preferable amount of modified polyolefin resin to be added is 0.1 to 15% by weight, preferably 0.2 to 12% by weight, and more preferably 0.5 to 10% by weight.
An inorganic filler or various additives may be added to the above-mentioned thermoplastic resin depending on the application of the molded product and the required property. Examples of inorganic filler include talc, calcium carbonate, calcium hydroxide, barium sulfate, mica, calcium silicate, clay, kaolin, silica, alumina, wollastonite, magnesium carbonate, magnesium hydroxide, titanium oxide, zinc oxide, and zinc sulfide. These materials may be used solely or in combination as required.
Examples of various additives include dispersant, lubricant, flame retardant, anti-oxidant, antistatic agent, anti-light agent, ultraviolet ray absorbing agent, carbon black, crystallization accelerator (nucleating agents), plasticizer, water absorbent, pigment, and dye. These materials may be used solely or in combination.
The pellet length of the fiber-reinforced thermoplastic resin pellet in accordance with the present invention is not particularly limited, but a pellet length of 2 to 24 mm is preferably used in view of the moldability and property of the molded product. A pellet length shorter than 2 mm results in the molded product with an insufficient property because of the short fiber length of thereinforcing fiber. On the other hand, a pellet length longer than 24 mm causes bridging at a hopper during the molding process and results in a difficult molding process. In view of these merits and demerits, the pellet length is preferably 3 to 18 mm, and more preferably 3 to 15 mm.
The pellet diameter is not particularly limited, but ranges from 1 to 5 mm, preferably 2 to 4 mm in view of the productivity and handling of the pellets during the molding process.
The preferable relation between the pellet length (L) and the pellet diameter (D) is represented by the aspect ratio. The preferable L/D ranges from 1 to 6. An L/D of less than 1 results in vertical cracking of the pellet during pelletizing, causing fluffing of the reinforcing natural fiber, and results in difficulty in handling. On the other hand, an L/D larger than 6 not only results in reduced pellet productivity because the pellet is too long and thin, but also results in the breaking of the pellet due to the jamming of pellets in a screw when it is used for injection molding. The reinforcing natural fiber is shortened due to breaking, and the breaking results in a poor mechanical property of the molded product. In view of the above, the preferable L/D ranges from 2 to 5.
The natural fiber used as a reinforcing fiber in the present invention is generally apt to deteriorate thermally from a temperature of approximately 150xc2x0 C. or higher, though this depends on the type of the natural fiber. Therefore, it is desirable that attention is paid to prevent the thermal deterioration of the natural fiber when thermoplastic resin with a high melting point or softening point is used. A low molten resin temperature is desirable when thermoplastic resin is impregnated in natural fiber, and a suitable temperature should be selected in view of the balance between the penetration of the resin into the natural fiber and the melt viscosity of resin that affects the drawing speed of the strand (fiber-reinforced resin strand impregnated with resin).
When thermoplastic resin is selected, thermoplastic resin with a melt viscosity suitable for impregnation in a natural fiber strand is selected, and the thermoplastic resin is heated to a sufficiently high temperature in the allowable range so that the melt viscosity becomes sufficiently low. Furthermore, the type of thermoplastic resin should be selected in view of the mechanical property of the molded product. For example, in the case of polypropylene resin, the melt flow rate (MFR: 230xc2x0 C., 2.16 kgf) is in a range from 10 g/10 min to 200 g/10 min, preferably in a range from 20 g/10 min to 150 g/10 min, and more preferably in a range from 30 g/10 min to 100 g/10 min. The molten resin temperature is in a range from 230 to 280xc2x0 C., preferably in a range from 240 to 260xc2x0 C., and more preferably in a range from 245 to 255xc2x0 C.
An MFR of the polypropylene resin smaller than the above-mentioned range results in reduced productivity of pellets that contain natural fiber and results in insufficient impregnation of resin into natural fiber even though the pellets can be manufactured. At that time, natural fiber is released partially from the obtained resin pellet resulting in poor handling, the natural fiber is dispersed insufficiently in the matrix resin when the molded product is manufactured, and the scattering of property becomes significant. On the other hand, an MFR larger than the above-mentioned range results in the disadvantage of poor material performance such as strength, modulus, and heat resistance.
The preferable natural fiber content in thermoplastic resin in accordance with the present invention is 10 to 65% by volume, and more preferably 12 to 60% by volume. If the natural fiber content is smaller than 10% by volume, the absolute quantity of natural fiber is insufficient and the property reinforcing function is exhibited insufficiently. On the other hand, if the natural fiber content is larger than 65% by volume, the impregnation of resin into natural fiber is apt to be insufficient, natural fiber is apt to be released from resin pellets to cause a problem in handling and a problem of bridging at part of a hopper of an injection molding machine. Furthermore, the high natural fiber content causes insufficient dispersion of reinforcing fiber in the molded product and the scattering of property becomes significant.
When resin pellets of the present invention are used as the molding material, a method may be employed, in which composite resin pellets with a high reinforcing fiber content, which is used as the master batch, is dry-blended with resin pellets formed of the same resin as the matrix resin of the composite resin pellets or a different resin compatible with the matrix resin of the composite resin to adjust the reinforcing fiber content to the desired value.
Resin pellets of the present invention are suitably used for manufacturing automobile parts (for example, inner panel), from which a large amount of waste is generated. The automobile parts obtained as described hereinbefore is excellent in strength and is helpful in reducing waste pollution.

Fiber-reinforced thermoplastic resin pellets and manufacturing method thereof


The invention is a diode having at least one trench in the semiconductor substrate and insulation configured on the surface of the semiconductor substrate so that the trench limits the depletion region of the diode and the area over which an electrode is in direct contact with the diffusion region of the diode is limited by the insulation. The diode has the advantage that the extent of the depletion region, and thus the area capacitance of the diode, and the size of the electrode are decoupled from one another. The lateral extent of the depletion region can be chosen independently of the size of the electrode.

The invention relates to a diode and a method for fabricating it. The invention relates, in particular, to a PIN diode. Diodes of this type are used, for example, in discrete circuits for switching radio frequency signals.
Diodes are used as rectifiers and switches in many areas of electronics and are offered commercially in various configurations. Applications as switches in the radio frequency range require diodes with a low blocking capacitance (CT) for an applied reverse-biased voltage, and a low forward resistance (rf) for a forward-biased voltage, which leads to low attenuation in the forward direction and high insulation in the reverse direction. One quality feature for PIN diodes is the product CT*rf.
The blocking capacitance of a diode, CT, is composed of an area capacitance, CA, and a fringing capacitance, CP. The area capacitance is dominant in large-area diodes. It is determined by the surface area and also the thickness of the depletion layer of the diode, which forms for a given voltage between the regions of different conductivity. Furthermore, the blocking capacitance is determined by the material of the semiconductor substrate or the relative permittivity of the semiconductor material. In the case of silicon, the relative permittivity is relatively high, with ∈=12.
The fringing capacitance encompasses all of the capacitances of a diode that cannot be assigned to the area capacitance. Examples of this are capacitances that are determined by the supply line and contact-making areas. The fringing capacitance is dominant primarily in small-area diodes.
The forward resistance can be minimized primarily by using short paths in the semiconductor substrate. This is achieved e.g. by the current, which enters from the front side through the diffusion layer, emerging again on the rear side of the semiconductor substrate. The rear side of this substrate has previously been thinned.
The PIN diodes have become established in the radio frequency range right into the GHz range (e.g. the diode family BAR-63 from Infineon Technologies AG). The active region of these diodes essentially includes three regions, a highly doped diffusion region of a first conduction type, a quasi intrinsic region with no doping or only very low doping and a highly doped region of a second conduction type. In the case of these diodes, the thickness of the depleted region is given essentially by the thickness of the intrinsic region, since the intrinsic region is completely depleted of free charge carriers even at very small voltages on account of the low doping. A relatively thick intrinsic region makes it possible to produce diodes that have very low blocking capacitances even at small voltages.
FIG. 5 is a cross sectional view taken through a prior art rotationally symmetrical planar PIN diode 10. The figure shows the semiconductor substrate 1, which has a p-conducting substrate region 3 and an intrinsic substrate region 5. The intrinsic substrate region 5 is generally realized by an undoped or only weakly doped epitaxial layer. The intrinsic region 5 is non-conducting and therefore acts as a kind of dielectric between the n-conducting diffusion region 7 and the p-conducting region 3. Furthermore, the diode has a rear side contact 17, which is preferably realized by a gold-arsenic layer, so that the rear side serves as a second contact of the diode. In order to minimize the resistance of the diode, the rear side of the semiconductor substrate is thinned.
The total capacitance of the diode is given by the sum of the area capacitance CA and the fringing capacitance CP, which are both depicted diagrammatically in FIG. 5. If the diode area is small, then the influence of the fringing capacitance must increasingly be taken into account. The fringing capacitance CP in FIG. 5 is relatively large, since the dielectric constant is essentially prescribed by the depleted silicon, which has a high dielectric constant (∈=12).
In order to reduce the fringing capacitance CP, so-called mesa diodes are often used for applications in radio frequency technology. FIG. 6 shows a cross sectional view taken through a rotationally symmetrical mesa PIN diode 30. In this case, due to the mesa structure, the fringing capacitance CP is significantly reduced in comparison with the diode shown in FIG. 5, since in the trench 20, air is prescribed as the dielectric, and air has a low dielectric constant (∈=1). The trench is covered by a trench oxide layer 22 and a nitride layer 24 lying on the latter, so that the silicon surface is passivated in the trench. The blocking capacitance of the diode typically lies below 400 fF.
For the same resistance in the forward direction, mesa PIN diodes make it possible to realize capacitances in the reverse direction that are approximately 15% smaller than the capacitances that are possible with a planar diode. A further advantage of a mesa PIN diode resides in the shorter turn-off time. This can be attributed to the fact that, as a result of the lateral delimitation of the charge carriers, during the switch-off, no charges can be removed from the edge region of the diode, as is the case with a planar diode.
However, the diode shown in FIG. 6 has the disadvantage that, for a given thickness of the intrinsic region, the junction capacitance is downwardly limited by the size of the electrode 9 that is required for contact-making. The area of the electrode 9 cannot be arbitrarily reduced, since later it is necessary to apply a bonding wire or another terminal connection on this area. This bonding wire or terminal connection connects the diode e.g. to a housing PIN. Conventional bonding methods require a bonding bearing area of about 10,000 xcexcm2 or more. This generally has the consequence that the size of the diffusion region 7 also cannot be reduced, since the contact-making area required for a microwelding connection must maintain a minimum size. Since the size of the electrode 9 is prescribed by the area required for contact-making, e.g. by a bonding wire, the reduction of the blocking capacitance of the diode is limited by this area. A further disadvantage is that, in the case of small diodes and thus also small contact-making areas, e.g. a bonding base of a bonding wire can reach across the contact area and can damage the insulating layers 22 and 24 even in the event of very small misalignments.
It is accordingly an object of the invention to provide a diode and a method for producing the diode which overcomes the above-mentioned disadvantages of the prior art apparatus and methods of this general type.
In particular, the object of the invention is to provide a diode having a desired, i.e. minimum, blocking capacitance even in the case of a predetermined minimum bonding area. Furthermore, the diode is intended to have the typical switching behavior of a mesa PIN diode.
With the foregoing and other objects in view there is provided, in accordance with the invention, a diode that in particular can be used for applications in radio frequency technology, including: a semiconductor substrate having a surface, a first region of a first conductivity type, a second region of a second conductivity type, and a depletion region between the first region and the second region being formed when the diode is operated in a reverse direction; at least one electrode configured on the surface of the semiconductor substrate, the first region having an area being directly electrically connected to the electrode; at least one trench formed in the semiconductor substrate; and insulation configured on the surface of the semiconductor substrate. The trench limits the depletion region that is formed when the diode is being operated in the reverse direction. The insulation limits the area of the first region that is directly electrically connected to the electrode.
The diode has the advantage that the extent of the depletion region, and thus the area capacitance of the diode, and the size of the electrode are decoupled from one another. The lateral extent of the depletion region can be chosen independently of the size of the electrode. The part of the electrode that is not in direct contact with the first region, but is necessary to provide a sufficiently large area for a bonding wire is arranged on the insulation. The insulation makes it possible to keep a part of the electrode at a sufficient distance from the semiconductor substrate, as a result of which the capacitance of the diode is reduced.
Therefore, the lateral extent of the depletion region can be optimally adapted to the respective application without having to consider problems that can result from bonding the diode. Furthermore, the diode has essentially the same small fringing capacitance as a mesa diode. The trench in the semiconductor substrate helps to lower the fringing capacitance of the electrode with respect to the semiconductor substrate, since rather than silicon with ∈=12, a material with a lower dielectric constant, e.g. silicon oxide with ∈=4 or gas with ∈=1, is provided in the edge region.
The trench is preferably filled with an insulating filling material having the smallest possible dielectric constant. The filling and also the insulation at the substrate surface have the effect that e.g. the bonding base of a bonding wire cannot project into the trench and the capacitance of the diode thus increases. The filling material should preferably have a dielectric constant that is less than that of silicon.
The diode preferably has a PIN diode structure, i.e. the semiconductor substrate has an undoped or only very weakly doped region on the surface. This very weakly doped region, also called an intrinsic region, is usually grown by an epitaxial method on the more highly doped semiconductor substrate. Therefore, for a given area geometry, the thickness of this epitaxial layer largely determines the capacitance of the diode.
A preferred filling material for the trench is silicon oxide. In a preferred embodiment, a borophosphosilicate glass (BPSG) oxide, in particular, is used for the filling of the trench. In accordance with a further preferred embodiment, prior to the filling, trench bottom and trench wall are covered with a layer made of undoped silicate glass, in order to minimize the area state density at the trench surface.
A cavity is preferably provided in the trench. A cavity leads to a further reduction of the fringing capacitance, since the dielectric constant of gas (air), with ∈=1, is significantly lower than that of silicon oxide.
The cavity or cavities are preferably fabricated in the insulating filling material by filling the cavity by a non-conformal deposition. During such a deposition, a so-called xe2x80x9cshrink hole formationxe2x80x9d arises since the trench cannot be completely filled on account of the increased deposition at the upper edge of the trench.
The electrode preferably contains aluminum, since a good ohmic contact on silicon can be realized with this material, and aluminum is well suited to contact-making with bonding wires made of gold or aluminum. Furthermore, it is preferred if more than 20%, and preferably more than 40%, of the electrode is arranged above the insulation.
With the foregoing and other objects in view there is also provided, in accordance with the invention, a method for fabricating a diode. The method includes steps of: providing a semiconductor substrate having a surface, a first region of a first conductivity type, a second region of a second conductivity type, and a depletion region forming between the first region and the second region when the diode is operated in a reverse direction; forming at least one trench limiting the depletion region; filling the trench with an insulating filling material; producing insulation on the surface of the semiconductor substrate; and producing an electrode on the surface of the semiconductor substrate such that the electrode is directly electrically connected to an area of the first region and the area is limited by the insulation.
In accordance with an added feature of the invention, the method includes: providing the semiconductor substrate with an intrinsic region.
In accordance with an additional feature of the invention, the method includes: performing the step of forming the trench by anisotropic etching.
In accordance with another feature of the invention, the method includes: coating walls and a bottom of the trench with an undoped silicate glass layer.
In accordance with a further feature of the invention, the method includes: performing the step of filling the trench by performing a non-conformal silicon oxide deposition so that a cavity forms in the trench.
In accordance with a further added feature of the invention, the method includes: using a BPSG process to perform the step of silicon oxide deposition.
In accordance with yet an added feature of the invention, the method includes: performing the step of filling the trench and performing the step of producing the insulation by depositing a silicon oxide layer and subsequently patterning the silicon oxide layer.
In accordance with yet an additional feature of the invention, the method includes: patterning the insulation in a trapezoid form.
In accordance with yet a further feature of the invention, the method includes: thinning a rear side of the semiconductor substrate.
In accordance with yet a further added feature of the invention, the method includes: providing a second contact on a rear side of the semiconductor substrate.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a diode and method for fabricating it, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Pin diode and method for fabricating the diode


This is a balloon catheter having braided layer which extends generally from the proximal end of the catheter to a location distal of the balloon. In particular, it is desirable that the shaft of the catheter proximal of the balloon be stiffest at the proximal section and least stiff just proximal of the balloon. Although the catheter may be a single lumen catheter using some type of a core wire to act as a valve for inflation and deflation of the balloon, it is within the scope of the invention to include either a separate inflation/deflation lumen or one incorporated into the various concentric polymeric layers used to make up the proximal shaft. Particularly preferred is the use of an elastic, compliant balloon.

This invention relates generally to a highly flexible catheter having a balloon at its distal tip. The form of the catheter is such that it may be used in various percutaneous transluminal angioplasty (PTA) procedures but is sufficiently flexible in its construction that it may be used for other diagnostic and treatment indications in regions of the body having significantly more tortuous vasculature.
For instance, in PTCA procedures, a guiding catheter typically having a preshaped distal tip is introduced into the vasculature of a patient. The catheter is advanced from the entry point, up into the aorta and, once at that site, is twisted or torqued from the proximal end of the catheter so to turn the preshaped distal tip of the guiding catheter in to the ostium of a desired coronary artery. A balloon-bearing or "dilatation" catheter is then advanced through the lumen of a guiding catheter and is progressed out the guiding catheter's distal tip until the balloon on the distal extremity of the dilatation catheter extends cross the region to be dilated. The balloon is then expanded, typically to a predetermined size dictated by the design of the balloon, via the use of radio-opaque liquid at relatively high pressures. Upon completion of the procedure, the balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the thus-treated artery.
In other procedures, a balloon-bearing catheter typically of a somewhat smaller diameter than a catheter used in PTA or PCTA might be used. In a universal sense, the procedure might be considered to be similar in that a larger or guiding catheter is initially placed so that its distal end is near the body site to be treated or diagnosed. The balloon-catheter, perhaps with the guidewire through an existing central lumen, would then be extended from the distal end of the guiding catheter to the site. The balloon is expanded and once the procedure is complete, the balloon is deflated and removed from the body. In some instances, the balloon might be of a compliant nature rather than the fixed diameter configuration found in a typical PTA balloon.
The advent of interventional radiology as a viable alternative in neurological regions of the body have produced demands on catheterization equipment not faced by demands placed on PTCA devices. The need for significantly smaller diameter devices, devices having a variable flexibility, ability to resist kinking (particularly in those regions where the differences in flexibility may be acute) is notable.
One way to produce strong catheter shafts for a balloon catheter is via the use of braids in those shafts. For instance, U.S. Pat. No. 5,338,295, to Cornelius et al. describes a dilatation balloon catheter having a shaft formed of a tubular stainless steel braid. The proximal outer tube section is encased in a polyimide material. The distal outer tube section which forms the balloon is made of a polymeric material such as polyethylene. The braid in this instance extends only partially down the proximal portion of the catheter. It does not extend as far as the balloon nor does it extend through the balloon.
Another similar device is shown in U.S. Pat. No. 5,451,209, to Ainsworth et al. Ainsworth et al. describes a composite tubular element useful in intravascular catheters. In particular it is shown as an element, variously of a fixed wire dilatation catheter and in a guiding or angiographic catheter. The structure of the device is made by braiding strands from a mixture of a polymeric matrix materials (such as fibers or powders) having a relatively low melting point and a high strength reinforcing fiber having a relatively high melting point. The fibers are woven into a tubular element; the resulting braided tubular element is heated to melt the low melting point matrix material so as to flow around the reinforcing fibers to form a matrix. Thermoplastic jackets or coatings are then extruded or otherwise applied to the exterior of the thus-produced braided tubular element. There is no suggestion in the patent to either produce a shaft which has variable stiffness proximally nor to use only a metallic braid from the proximal end of a over the wire catheter to a position distal of the balloon.
U.S. Pat. No. 5,429,597 to DeMello, teaches a balloon catheter which is said to be kink resistant. In general, it appears to be made up of an outer polymeric covering over a "cross-wound multifilar (CWMF)" coil and a non-fixed, removable core wire. The CWMF coil is a pair of helical coils which are wound in opposite directions to provide for torque transmission during use. There appears to be no suggestion of weaving the CWMF into a braid. There is no suggestion of extending the CWMF through the length of the balloon interior.
The PCT application to Pray et al. (WO 93/20881) assigned to Scimed Medical Systems suggests a dilatation catheter having a shaft with a proximal section which is a composite of polymeric material and a stainless steel braid tube. The distal section of the catheter is formed of a flexible polymeric tube. In one embodiment of the described device, the braid weave of the proximal section of the shaft has a varying pick count, increasing in the distal direction, thereby providing for increased flexibility in the distal direction. However, this document does not suggest the use of a braided tube extending distally of the balloon. Furthermore, there is no suggestion of the use of an elastomeric or rubbery balloon on the device.
Published UK Patent Application G.B. 2,233,562A, by Hannam et al., shows a balloon catheter having a flexible, hollow inner shaft and an outer braided shaft with a balloon inflated by fluid introduced between the inner and outer shafts. The inner shaft is fixed relative to the outer shaft at both ends. When the balloon is inflated, the outer shaft shortens. The excess length of the inner shaft is accommodated via the inner shaft bending into a coil-like form. The braid is said typically to be of a fabric of a polyester floss. It is said to extend the entire length of the outer shaft but with a varying pick rate apparently in the neighborhood of the balloon. The balloon is made of the material of the loose braided layer and a flexible, elastic polyurethane. There is no suggestion of using the braided material as an overall stiffener in the balloon catheter device. There is no suggestion of placing the braid on the interior of the balloon.
None of the published documents teaches the inventive balloon catheter.