The present invention provides an ionizing radiation irradiated rubber molded product and a process for preparing the same, the rubber molded product being prepared by irradiating with an ionizing radiation a preform comprising 5 to 95% by weight of a fluororubber containing vinylidene fluoride copolymerized therein in a proportion of 45 to 88 mole % and having a number average molecular weight of 5,000 to 200,000, and 95 to 5% by weight of an acrylic rubber.

The present invention relates to ionizing radiation irradiated rubber molded product and to a process for preparing the same.
Acrylic rubbers have higher heat resistance and oil resistance than conventional general-purpose rubbers and are in use for various kinds of industrial seal materials.
However, the acrylic rubbers are not fully satisfactory in compression set and heat resistance at temperatures not lower than 150xc2x0 C. and are unusable for seal materials, hoses and electrical wires at such temperatures.
On the other hand, fluororubbers are excellent in heat resistance, compression set, oil resistance and resistance to chemicals and are useful in the field of industrial materials and other fields. Nevertheless, it appears unlikely that the fluororubbers will be used in remarkably increased quantities in spite of their outstanding properties since economy is not negligible for prevalent use in these fields. Additionally, fluororubbers have the drawback of deteriorating in the presence of additives (especially amine compounds) contained in engine oils.
Investigations were conducted to develop materials having the characteristics of both acrylic rubbers and fluororubbers by blending a common acrylic rubber with a common fluororubber and vulcanizing the blend for molding with use of vulcanizers for one or both of the rubbers, whereas the method failed to fully vulcanize one or both of the rubbers, giving products which were unsatisfactory in physical properties such as mechanical strength and compression set, heat resistance, and other properties.
Materials have been developed which render a fluororubber and an acrylic rubber peroxide-cocrosslinkable to overcome the foregoing drawbacks (WO 96/17890). Yet, products unsatisfactory in mechanical strength were obtained by crosslinking methods using conventional crosslinking agents.
An object of the present invention is to provide an ionizing radiation irradiated rubber molded product which is excellent in heat resistance, compression set, oil resistance, resistance to chemicals and resistance to additives and which is improved in mechanical strength.
The present invention provides an ionizing radiation irradiated rubber molded product as described below and a process for preparing the same.
The ionizing radiation irradiated rubber molded product of the present invention is prepared by irradiating with an ionizing radiation a preform comprising 5 to 95% by weight of a fluororubber containing vinylidene fluoride copolymerized therein in a proportion of 45 to 88 mole % and having a number average molecular weight of 5,000 to 200,000, and 95 to 5% by weight of an acrylic rubber.
Stated more specifically, the rubber molded product of the invention is prepared by preforming the following rubber composition, and irradiating the preform with an ionizing radiation.
According to the rubber molded product of the invention, examples of fluororubbers are vinylidene fluoride copolymers such as vinylidene fluoride/hexafluoropropylene, vinylidene fluoride/ tetrafluoroethylene/hexafluoropropylene and vinyl idene fluoride/chlorotrifluoroethylene; copolymers such as tetrafluoroethylene/propylene, hexafluoropropylene/ethylene and fluoro(alkyl vinyl ether)/olefin (for example, vinylidene fluoride/tetrafluoroethylene/perfluoroalkyl vinyl ether), etc. Preferable among these are elastomers of vinylidene fluoride/hexafluoropropylene and vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene. The fluoro(alkyl vinyl ether) may contain a plurality of ether linkages. These fluororubbers are 5,000 to 200,000, preferably 50,000 to 170,000, in molecular weight, i.e., in number average molecular weight. The fluororubber fails to give satisfactory processability if exceeding 200,000 in molecular weight, while fully acceptable characteristics are unavailable after vulcanization if the molecular weight is lower than 50,000. The term processability means the vulcanization characteristics and amenability to rolling process and mold process. The proportion of copolymerized vinylidene fluoride in the fluororubber is 45 to 88 mole %, preferably 55 to 85 mole %.
The fluororubber is low in compatibility with acrylic rubbers and encounters difficulty in giving higher dispersibility to polymers and sufficient mechanical property is not obtained if less than 45 mole % in the proportion of copolymerized vinylidene fluoride. Impaired compression set will result if this proportion exceeds 88 mole %.
The peroxide-crosslinkable fluororubber has a crosslinking moiety in the molecule, such as iodine, bromine, double bond or the like which moiety will undergo crosslinking reaction in the presence of a peroxide radical.
The fluororubbers of the invention include, for example, iodine-containing fluororubbers, which will be described below.
The preferred examples of iodine-containing fluororubbers include a readily curable fluororubber (see JP-A-125491/1978) which is obtained by polymerizing vinylidene fluoride (VdF) and at least one of monomers comprising a fluorine-containing ethylenically unsaturated compound having 2 to 8 carbon atoms (and when required, a fluorine-free ethylenically unsaturated compound having 2 to 4 carbon atoms) in the presence of a radical generator and an iodine compound represented by the formula RIx (wherein R is a saturated or unsaturated fluorohydrocarbon group having 1 to 16 carbon atoms, chlorofluorohydrocarbon group or hydrocarbon group having 1 to 3 carbon atoms, and x, which is the number of bonds of R, is an integer of not smaller than 1). Useful iodine-containing fluororubbers are copolymers containing 45 to 88 mole %, preferably 55 to 85 mole %, of vinylidene fluoride (VdF) unit, 0 to 45 mole %, preferably 0 to 30 mole %, of tetrafluoroethylene (TFE) unit and 10 to 40 mole %, preferably 10 to 25 mole %, of hexafluoropropylene (HFP) unit.
The acrylic rubber for use in preparing the ionizing radiation irradiated rubber molded product of the present invention is preferably a multi-polymer rubber comprising (a) 30 to 99.9% by weight of (meth)acrylic alkyl ester and/or (meth)acrylic alkoxy-substituted alkyl ester, (b) 0.1 to 10% by weight of a crosslinkable monomer and (c) 0 to 70% by weight of other ethylenically unsaturated compound copolymerizable with the components (a) and (b).
Examples of the above (meth)acrylic alkyl ester to be used herein are, for example, compounds represented by the formula
CH2=C(R1)COOR2
wherein R1 is a hydrogen atom or methyl, and R2 is alkyl having 1 to 18 carbon atoms. Examples of such monomers are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-methylpentyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate and n-octadecyl (meth)acrylate. Among them, preferable are methyl acrylate, ethyl acrylate, n-propyl acrylate and n-butyl acrylate, and more preferable are methyl acrylate and ethyl acrylate.
Examples of the above (meth)acrylic alkoxy-substituted alkyl ester are compounds represented by the formula
CH2=(R1)COO-A-O-R3
wherein A is alkylene having 1 to 12 carbon atoms, R1 is as defined above and R3 is alkyl having 1 to 12 carbon atoms. Examples of such compounds are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(n-propoxy)ethyl (meth)acrylate, 2-(n-butoxy)ethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-(n-propoxy)propyl (meth)acrylate and 2-(n-butoxy)propyl (meth)acrylate. Among them, preferred are 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate, and more preferred is 2-methoxyethyl acrylate.
Examples of the above crosslinkable monomer are dicyclopentadiene, ethylidenenorbornene, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinyl (meth)acrylate, allyl (meth)acrylate, glycidyl (meth)acrylate, dimethyl stearyl vinylsilane, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, alkyl glycidyl ether, vinyl glycidyl ether, 2-chloroethyl (meth)acetate, vinyl monochloroacetate, vinylnorbornene, acrylic acid, methacrylic acid and itaconic acid. There are used singly or in a mixture of at least two of them.
Examples of the above ethylenically unsaturated compound are unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, 2-pentenic acid, maleic acid, fumaric acid and itaconic acid; alkyl vinyl ketone such as methyl vinyl ketone; vinyl or allyl ether such as vinyl ethyl ether and allyl methyl ether; vinyl aromatic compounds such as styrene, xcex1-methylstyrene, chlorostyrene and vinyltoluene; xcex1,xcex2-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated amides such as acrylamide, methacrylamide and N-methylolacrylamide; ethylene; propylene; vinyl chloride; vinylidene chloride; vinyl fluoride; vinylidene fluoride; vinyl acetate; and alkyl fumarate. Among these preferable are acrylonitrile, ethylene and vinyl acetate, and particularly preferable are acrylonitrile and ethylene.
As the acrylic rubber of the present invention, it is preferable to use an acrylic rubber obtained by copolymerizing, as a crosslinkable monomer, a polyfunctional monomer having (a) a functional group rendering the acrylic rubber peroxide-cocrosslinkable with the fluororubber and (b) a functional group effecting the copolymerization with a (meth)acrylic ester.
The polyfunctional monomer has at least two double bonds in the molecule and possesses (a) a functional group rendering the acrylic rubber peroxide-cocrosslinkable with the fluororubber and (b) a functional group effecting the copolymerization with a (meth)acrylic ester. Examples of polyfunctional monomers are ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, allyl (meth)acrylate, divinylbenzene, triallylcyanurate and triallyl isocyanurate. Bifunctional monomers are desirable because use of a monomer having three or more functional groups is likely to present difficulty in controlling the proportion of partially crosslinked component in the resulting copolymer. When the monomer has only one double bond in the molecule, no crosslinking group remains in the acrylic rubber, which therefore is difficult to be cocrosslinked along with the fluororubber. More desirable among the bifunctional monomers are those wherein two double bonds are different in reactivity in order to permit one of the double bonds to remain in the acrylic rubber as a crosslinking group. More preferable is allyl (meth)acrylate. Although dihydrodicyclopentenyl acrylate and ethylidene norbornene are included in monomers wherein the two double bonds are different in reactivity, these are not usable singly and have to be used conjointly with allyl (meth)acrylate. This is because the bifunctional monomer must be fully crosslinkable with the same auxiliary crossliking agent as is useful for the fluororubber.
The polyfunctional monomer is used in an amount of 0.1 to 1.5 wt. %, preferably 0.3 to 0.7 wt. %, based on the combined amount of (meth)acrylic ester, acrylonitrile and polyfunctional monomer. If a smaller amount of polyfunctional monomer is used, the acrylic rubber will not be crosslinked sufficiently, presenting difficulty in vulcanization molding and resulting in low heat resistance and poor mechanical properties. An excess of polyfunctional monomer, if used, produces an increased amount of partially crosslinked component in the copolymer, leads to impaired processability and causes vulcanization to result in an excessively high crosslinking density, consequently giving a material which is no longer flexible, impaired in elongation and unusable for materials such as an electric wire, hose, tube, seal or the like.
According to the rubber molded product of the invention, the ratio of the fluororubber to the acrylic rubber, i.e., flurororubber/acrylic rubber, is 5xcx9c95/95xcx9c5 by weight, preferably 10xcx9c90/90xcx9c10, more preferably 25xcx9c75/75xcx9c25. If a lesser amount of fluororubber is used, the resulting material will not have sufficiently improved heat resistance and oil resistance and will be impaired in processability including flowability, whereas an excess of the fluororubber is undesirable economically and brings low resistance to additives.
When required, a suitable auxiliary crosslinking agent may be used conjointly in order to accelerate crosslinking due to irradiation with ionizing radiation. As a rule, useful auxiliary crosslinking agents are not limited particularly in type insofar as they are reactive on polymer radicals. Examples of desirable agents are triallyl cyanurate, triallyl isocyanurate, triallylformal, triallyl trimellitate, dipropargyl terephthalate, diallyl phthalate, tetraallylterephthalamide, triallyl phosphate, bismaleimide, etc. Although the auxiliary crosslinking agent need not always be used, the amount thereof to be used is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polymers to be used.
When crosslinking is carried out with heating in a preforming process, it is necessary to use singly or combinedly crosslinking agents conventionally employed for the fluororubber and/or acrylic rubber used, and it is optional to use singly or combinedly crosslinking auxiliaries conventionally employed for the fluororubber and/or acrylic rubber used.
For example, when using a peroxide-crosslinkable fluororubber and acrylic rubber in combination, it is preferable to use a crosslinking agent which readily generates peroxy radicals when heated or subjected to redox. Examples of such agents are 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxy peroxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, xcex1,xcex1xe2x80x2-bis(tert-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, benzoyl peroxide, tert- butylperoxybenzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylperoxymaleic acid, tert-butylperoxyisopropyl carbonate, etc. Preferable among these are dialkyl compounds. The kind of agent and the amount thereof to be used are determined in view of the amount of active xe2x80x94Oxe2x80x94Oxe2x80x94 and the decomposition temperature. The amount is usually 0.1 to 15 parts by weight, preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polymers (combined amount of acrylic rubber and fluororubber).
As a rule, useful auxiliary crosslinking agents are not limited particularly in type insofar as they are reactive on peroxy radicals and polymer radicals. Examples of desirable agents are triallyl cyanurate, triallyl isocyanurate, triacrylformal, triallyl trimellitate, dipropargyl terephthalate, diallyl phthalate, tetraallylterephthalamide, triallyl phosphate, bismaleimide, etc. Although the auxiliary crosslinking agent need not always be used, the amount thereof to be used is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polymers to be used.
According to the rubber molded product irradiated with ionizing radiation of the invention, fillers, processing aids, antioxidants, age resistens, antiozonants, ultraviolet absorbers, flame retardants, etc. can be added to the composition when required.
Examples of useful fillers are magnesium oxide, calcium oxide, titanium oxide, silicon oxide, aluminum oxide and like metal oxides, magnesium hydroxide, aluminum hydroxide, calcium hydroxide and like metal hydroxides, magnesium carbonate, aluminum carbonate, calcium carbonate, barium carbonate and like carbonates, magnesium silicate, calcium silicate, sodium silicate, aluminum silicate and like silicates, aluminum sulfate, calcium sulfate, barium sulfate and like sulfates, synthetic hydrotalcite, molybdenum disulfide, iron sulfide, copper sulfide and like metal sulfides, kieselguhr, asbestos, lithopone (zinc sulfide/barium sulfate), graphite, carbon black, carbon fluoride, calcium fluoride, coke, etc.
Examples of processing agents are stearic acid, oleic acid, palmitic acid, lauric acid and like higher fatty acids, sodium stearate, zinc stearate and like higher fatty acid salts, stearic acid amide, oleic acid amide and like higher fatty acid amides, ethyl oleate and like higher fatty acid esters, stearylamine, oleylamine and like higher aliphatic amines, carnauba wax, ceresin wax and like petroleum wax, ethylene glycol, glycerin, diethylene glycol and like polyglycols, vaseline, paraffin and like aliphatic hydrocarbons, silicone oil, silicone polymers, low-molecular-weight polyethylene, phthalic acid esters, phosphoric acid esters, rosin, (halogenated) dialkylamines, (halogenated) dialkylsulfones, etc.
Examples of antioxidants, age resistens and antiozonants are 2,5-di-tert-amylhydroquinoline and like phenolic compounds, 2,2,4-trimethyl-1,2-dihydroquinoline and like amine-ketone compounds, 4,4xe2x80x2-bis (xcex1,xcex1xe2x80x2-dimethylbenzyl) diphenylamine and like aromatic secondary amine compounds.
Examples of ultraviolet absorbers are 2,4-dihydroxybenzophenone and like benzophenone compounds, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate and like amine compounds, 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole and like benzotriazole compounds.
Useful flame retardants include, for example, antimony trioxide, antimony pentoxide, sodium antiomonate, aluminum hydroxide, magnesium hydroxide, zinc borate, guanidine and like inorganic flame retardants, tris(chloroethyl)phosphate, tris(monochloropropyl)phosphate, tris(dichloropropyl)phosphate, triallylphosphate, halogen-containing condensed ester of organic phosphoric acid, ammonium polyphosphate, red phosphorus flame retardants and like esters of phosphoric acid and phosphorus compounds, chlorinated paraffin, chlorinated polyolefin, chlorinated polyethylene, perchlorocyclopenta-decane and like chlorine flame retardants, hexabromobenzene, decabromodiphenyl oxide, dibromoneopentyl glycol, tetrabromo-bisphenol A derivatives, tris-(2,3-dibromopropyl-1)isocyanurate, hexabromocyclodecane, brominated epoxy resins and like bromine flame retardants, etc. These flame retardants can be used either alone or in combination.
The rubber composition to be used for the ionizing radiation irradiated rubber molded product of the present invention can be prepared by a process using a conventional mixing device, such as a process wherein a fluororubber, an acrylic rubber and other components are mixed by an open roll mill or by an internal mixer or a process wherein the emulsion is coagulated. These processes may be carried out in combination.
The preform can be produced from the foregoing rubber composition by conventional methods, such as a method wherein the composition is heated and pressed by a mold, a method wherein the composition is forced into a heated mold and a method wherein the composition is extruded by an extruder. In the case of extrudates such as hoses and electrical wires, the extrudate can retain its shape after extrusion so that the preform obtained by extrusion without use of a crosslinking agent can be used as it is. Of course, it is possible to use a preform prepared by crosslinking using a crosslinking agent with heating by steam or the like. When a molded product such as O-rings, gaskets, oil seals, diaphragms or the like entails difficulty in retaining their shape in a non-crosslinked state after release from the mold, these moldings can be prepared from the preform prepared by crosslinking with a crosslinking agent.
According to the present invention, the obtained preform is irradiated with an ionizing radiation to undergo crosslinking reaction.
Ionizing radiations to be irradiated to the preform in the invention include, for example, X-rays, gamma rays, electron rays, proton rays, deuteron rays, alpha rays, beta rays and the like. The ionizing radiation is irradiated preferably in an inert gas or in a vacuum, although in the air with a good result.
An ionizing radiation is applied to the preform at a dose of preferably 5 to 500 kGy, more preferably 10 to 300 kGy. If the dose is less than 5 kGy, the application of ionizing radiation fails to satisfactorily improve the mechanical strength, whereas a dose of higher than 500 kGy results in accelerated degradation of polymer, partial cutting of intermolecular bond and lower mechanical strength. A dose ratio for improvement of mechanical strength is preferably 500 or more kGy/h, more preferably 1000 or more kGy/h.
Rubber moldings irradiated with an ionizing radiation according to the present invention can endure use under severe conditions and can be properly used for various purposes as is the case with fluororubbers, acrylic rubbers or blends thereof. The molded products of the invention have suitable properties for gaskets, contact-type or non-contact-type packings and like seals (self-seal packings, piston rings, separated ring-shaped packings, mechanical seals, oil seals, etc.), bellows, diaphragms, hoses, tubes, electrical wires, etc. which require resistances to heat, oil, fuels, LLC and steam, for automotive engine body, main kinetic system, kinetic valves, lubricating/cooling system, fuel system, suction/exhaustion system, transmission system for driving system, steering system on a chassis, braking system, basic electrical components for electrical equipment, electrical components for control system, electrical components for equipment, etc.
Stated more specifically, the rubber molded products of the invention can be used for the following purposes.
Rubber products for an engine body including cylinder head gaskets, cylinder head cover gaskets, oil pan packings, gaskets for general use, O-rings, packings, timing belt cover gaskets and like seals, control hoses and like hoses, rubber means for prevention of swinging an engine mount, etc.
Rubber products for main kinetic system, including crank shaft seals, cam shaft seals and like shaft seals, etc.
Rubber products for kinetic valves including valve stem oil seals for engine valves, etc.
Rubber products for lubricating/cooling system, such as hoses for engine oil coolers, oil return hoses, seal gaskets, etc., water hoses around radiators, oil hoses for vacuum pumps, etc.
Rubber products for fuel system such as oil seals for fuel pumps, diaphragms, valves, etc., filler (neck) hoses, hoses for supply of fuels, hoses for return of fuels, vaper (vaporable) hoses and like fuel hoses, in-tank hoses for fuel tanks, filler seals, tank packings, in-tank fuel pump mounts, etc., tube bodies for fuel tubes, connector O-rings, etc., injector cushion rings for fuel ejection devices, injector seal rings, injector-O-rings, pressure regulator diaphragms, check valves, etc., core valves for needle valves in carburetors, accelerating pump pistons, flange gaskets, control hoses, etc., valve sheets, diaphragms and the like for combined air control (CAC) apparatus, etc.
Rubber products for suction and exhaustion system such as intake manifold packings and exhaust manifold packings for manifold devices, diaphragms, control hoses, emission control hoses, etc. for EGR (exhaust gas recycle), diaphragms for back pressure transducers (BPT), etc., valve sheets for preventing afterburn (AB) in afterburn valves, etc., throttle body packings for throttles, turbo-oil hoses (supply), turbo-oil hoses (return), turbo-air hoses, intercooler hoses, turbine shaft seals, etc. for turbochargers, etc.
Rubber products for transmission system such as transmission-related bearing seals, oil seals, O-rings, packings, torque converter hoses, etc., mission oil hoses, automatic transmission fluid (ATF) hoses, O-rings, packings, etc. for AT (automatic transmission), etc.
Rubber products for steering system such as power steering oil hoses, etc.
Rubber products for brake system such as oil seals, O-rings, packings, brake oil hoses, etc., air valves, vacuum valves, diaphragms, etc. for master backs, piston cups (rubber cups), caliper seals, boots, etc. for master cylinder, etc.
Rubber products for basic electrical components such as insulators and sheaths for electrical wires (harness), tubes for harness exterior components, etc.
Rubber products for electrical components in control system such as coating materials for sensor wires, etc.
Rubber products for electrical components in equipment such as O-rings, packings, cooler hoses, etc. for automotive air conditioners.
Rubber products for other machinery than automobiles including, for example, packings, O-rings, hoses and other seal materials, insulators and sheaths for electrical wires, diaphragms, valves, etc. for resistances to oil, chemicals, heat, steam and weather in ships, aircraft and like transportation means, similar packings, O-rings, seal materials, insulators and sheaths for electrical wires, diaphragms, valves, hoses, rolls, tubes, coatings or linings for resistance to chemicals, etc. in chemical plants, similar packings, O-rings, hoses, seal materials, insulators and sheaths for electrical wires, belts, diaphragms, valves, rolls, tubes, etc. in machinery in food plants and devices for foods (including household devices), similar packings, O-rings, hoses, seal materials, insulators and sheaths for electrical wires, diaphragms, valves, tubes, etc. in devices of nuclear power plants, similar packings, O-rings, hoses, seal materials, insulators and sheaths for electrical wires, diaphragms, valves, rolls, tubes, linings, mandrels, flexible joints, belts, rubber plates, weather strips, roll blades for PPC copying machines, etc. in general industrial components, and so on.
The invention will be described below in greater detail with reference to the following examples and comparative examples. Parts are all by weight.
a) Polymerization of Acrylic Rubber
Into a separable flask equipped with a thermometer, stirrer, nitrogen supply tube and evacuating device were placed 480 parts of water, 0.24 part of sodium bicarbonate, 0.48 part of sodium laurylsulfate, 0.48 parts of Nonipole 200 (polyoxyethylene nonylphenyl ether) and 100 parts of monomer mixture of Table 1, the oxygen within the system was thoroughly removed by repeating evacuation and nitrogen replacement, and 0.01 part of sodium hydrosulfite, 0.002 part of sodium formaldehyde sulfoxylate and 0.005 part of tert-butyl hydroperoxide were thereafter placed in to start a polymerization reaction at 50xc2x0 C. The reaction was continued for 6 hours so as to achieve a polymerization conversion within the range of 95 to 99%, followed by salting-out of the reaction mixture, sufficient washing with water and drying to obtain an acrylic rubber. Incidentally, EA stands for ethyl acrylate, BA for butyl acrylate and AN for acrylonitrile. xe2x80x9cAcrylic ester A,xe2x80x9d brand name of Mitsubishi Rayon Co., Ltd. was used as it was as allyl methacrylate (hereinafter abbreviated as xe2x80x9cAMAxe2x80x9d)
b) Polymerization of Fluororubber
Into a polymerization reactor made of stainless steel and having a capacity of 3 liters were placed 1 liter of pure water and 2 g of C7F15COONH4 serving as an emulsifier, the interior of the system was fully replaced by nitrogen gas, and an initial monomer mixture of VdF/HFP/TFE was forced into the reactor at 80xc2x0 C. to an internal pressure of 16 kg/cm2 G. Subsequently, 10 ml of a 0.2 wt. % aqueous solution of ammonium persulfate was forced in to start a reaction.
Since the pressure dropped with the progress of the polymerization reaction, I(CF2)4I serving as a molecular weight adjusting agent was forced in upon a pressure drop to 15 kg/cm2 G. When the pressure further dropped to 14 kg/cm2 G, the system was repressurized with a continuous monomer mixture of VdF/HFP/TFE to the pressure of 16 kg/cm2 G. The aqueous solution of ammonium persulfate was forced into the system with nitrogen gas every 3 hours in an amount of 10 ml each time to continue the reaction with repeated decrease and increase in the pressure to obtain an aqueous emulsion.
To the emulsion was added a 5 wt. % aqueous solution of potash alum for coagulation, and the coagulated product was washed with water and dried to obtain a rubberlike copolymer. The initial monomer mixture, the amount of I(CF2)4I, continuous monomer mixture, reaction time and yield are listed in Table 2, in which 2F stands for VdF (vinylidene fluoride), 4F for TFE (tetrafluoroethylene) and 6F for HFP (hexafluoropropylene).
The number average molecular weight of the copolymer and Mooney viscosity (ML1+10, 100xc2x0 C.) were determined by the following method.
[Conditions for Determining Molecular Weight]
Gel permeation chromatograph: High performance GPC device, HLC-8020 (product of Toso Co., Ltd.)
Columns: TSK guard column Hhr-H (one),
TSK gel-G5000H, -G4000H, -G3000H, -G2000H (one each) (products of Toso Co., Ltd.)
Sensor: RI sensor (differential reflectometer) incorporated in HLC-8020
Data analysis: Supersystem Controller SC-8020 (product of Toso Co., Ltd.)
Developer solvent: Tetrahydrofuran
Temperature: 35xc2x0 C.
Concentration: 0.5 wt. %
Standard polymers for molecular weight calibration curve: Monodisperse polystyrenes, TSK standard POLYSTYREN [Mw/Mn=1.14 (max)] (product of Toso Co., Ltd.)
The composition of the copolymer was determined by 19F NMR measurement.
Mooney viscosity was measured according to JIS K-6300.

Molded rubber irradiated with ionizing radiation and process for producing the same


A non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends is produced by the method comprising, in a first step, forming a fire retardant mixture comprising a non-halogenated fire retardant, poly(arylene ether) resin and polystyrene resin by intimately mixing in melt; and in a second step, forming the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend by intimately mixing in melt the fire retardant mixture with a blowing agent.

Not Applicable
This invention relates to the field of expandable poly(arylene ether)/polystyrene compositions and more particularly to the field of flame retardant expandable poly(arylene ether)/polystyrene compositions.
Increasingly plastics are being used to replace metals in a wide variety of applications ranging from car exteriors to aircraft interiors. Flame retardant plastics have been especially useful, particularly in applications such as housings for electronic devices. The use of plastic instead of metal decreases weight, improves sound dampening and makes assembly of the device easier. Flame resistance has been dominantly provided by halogenated flame retardants. However, plastics employing halogenated flame retardants release toxic gas when heated to elevated temperatures and produce non recyclable waste streams. As a result non-halogenated fire resistant materials are in demand for a wide range of applications.
The most widely used process for making expandable poly(arylene ether)/polystyrene is via the styrene suspension polymerization process. Terminally end capped poly(arylene ether) resin is dissolved in the styrene monomer prior to polymerization and polymerization proceeds by the suspension process. During or at the end of polymerization a blowing agent is added. At the end of the process poly(arylene ether)/polystyrene expandable beads are recovered. Terminally endcapped poly(arylene ether) resin is required so the poly(arylene ether) resin does not inhibit the polymerization of the styrene. Unfortunately, the capping agent introduces by products and interferes with polymerization, resulting in low yield. Additionally, the poly(arylene ether) resin has limited solubility in the monostyrene, restricting the amount of poly(arylene ether) resin that can be added to the blend. This, in turn, limits the high temperature properties of the resulting poly(arylene ether)/polystyrene materials. The high viscosity of the composition limits the amount of additives, such as flame retardants and impact modifiers that can be included. Furthermore, only halogenated flame retardants may be used. Thus the styrene polymerization process for making expandable poly(arylene ether)/polystrene has several drawbacks including limited poly(arylene ether) resin solubility, modified poly(arylene ether) resin is required, a halogenated flame retardant is required, and high viscosity. These drawbacks limit the potential to manufacture expandable poly(arylene ether)/polystyrene materials with advanced properties through the suspension process.
Non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends are produced by the method comprising, in a first step, forming a fire retardant mixture comprising a non-halogenated fire retardant, poly(arylene ether) resin and polystyrene resin by intimately mixing in melt; and in a second step, forming the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend by intimately mixing in melt the fire retardant mixture with a blowing agent.
The above discussed and other features and advantages will be appreciated and understood by those skilled in the art from the following detailed description.
Not Applicable
A non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend is produced by the method comprising, in a first step, forming a fire retardant mixture comprising a non-halogenated fire retardant, poly(arylene ether) resin polystyrene resin and optional impact modifier by intimately mixing in melt; and, in a second step, forming the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend by intimately mixing in melt the fire retardant mixture with a blowing agent. Preferably the first step is performed in a first extruder and the second step is performed in a tandem extruder comprising extruder A and extruder B. Intimate mixing of the fire retardant mixture and blowing agent to form a non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend occurs in extruder A of the tandem extruder and cooling of the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend occurs in extruder B of the tandem extruder. Cooling of the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend prevents premature foaming of the blend at the die.
The non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends exhibit excellent molding performance and excellent fire retardant properties at various thicknesses while maintaining desirable heat dimensional stability. Surprisingly, the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends exhibit better fire retardant properties, namely short flame out time and non flaming drip behavior, than conventional halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends. The non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends can achieve an HBF rating or better in the UL ASTM D 4986/ISO/DIS 9772.3 flammability test, something not previously seen in an expandable poly(arylene ether)/polystyrene blend. The excellent fire retardant properties are unexpected and are believed to be the result of the thorough distribution of the non-halogenated fire retardant throughout the expandable poly(arylene ether)/polystyrene blend. The non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends do not require specially end capped poly(arylene ether) resin, have on line processability, can be colored to a wide range of colors and have a wide range of thermal properties.
An additional advantage of the method to produce poly(arylene ether)/polystyrene blends herein described is the ability to incorporate significantly larger amounts of poly(arylene ether) into the blend than currently possible using the suspension polymerization process. As previously mentioned poly(arylene ether) has limited solubility in mono styrene thus restricting the amount of poly(arylene ether) present in a poly(arylene ether)/polystyrene blend produced by suspension polymerization. In contrast, the method herein described can incorporate about 25 weight percent (wt %) of poly(arylene ether) or greater, preferably about 40 wt % or greater or even more preferably about 50 wt % or greater, based on the weight of the composition.
All conventional poly(arylene ether)s can be employed. The term poly(arylene ether) includes polyphenylene ether (PPE) and poly(arylene ether) copolymers; graft copolymers; poly(arylene ether) ether ionomers; and block copolymers of alkenyl aromatic compounds, vinyl aromatic compounds, and poly(arylene ether), and the like; and combinations comprising at least one of the foregoing; and the like. Poly(arylene ether)s per se, are known polymers comprising a plurality of structural units of the formula (I):
wherein for each structural unit, each Q1 is independently halogen, primary or secondary lower alkyl (e.g., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or the like; and each Q2 is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy, halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or the like. Preferably, each Q1 is alkyl or phenyl, especially C1-4 alkyl, and each Q2 is hydrogen.
Both homopolymer and copolymer poly(arylene ether) are included. The preferred homopolymers are those containing 2,6-dimethylphenylene ether units. Suitable copolymers include random copolymers containing, for example, such units in combination with 2,3,6-trimethyl-1,4-phenylene ether units or copolymers derived from copolymerization of 2,6-dimethylphenol with 2,3,6-trimethylphenol. Also included are poly(arylene ether) containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes, as well as coupled poly(arylene ether) in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two poly(arylene ether) chains to produce a higher molecular weight polymer. Poly(arylene ether)s of the present invention further include combinations comprising at least one of the above.
The poly(arylene ether) generally has a number average molecular weight of about 3,000-40,000 atomic mass units (amu) and a weight average molecular weight of about 20,000-80,000 amu, as determined by gel permeation chromatography. The poly(arylene ether) may have an intrinsic viscosity of about 0.10 to about 0.60 deciliters per gram (dl/g), preferably about 0.29 to about 0.48 dl/g, as measured in chloroform at 25xc2x0 C. It is also possible to utilize a high intrinsic viscosity poly(arylene ether) and a low intrinsic viscosity poly(arylene ether) in combination. Determining an exact ratio, when two intrinsic viscosities are used, will depend somewhat on the exact intrinsic viscosities of the poly(arylene ether) used and the ultimate physical properties that are desired.
The poly(arylene ether) are typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generally employed for such coupling; they typically contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.
Particularly useful poly(arylene ether) for many purposes are those which comprise molecules having at least one aminoalkyl-containing end group. The aminoalkyl radical is typically located in an ortho position to the hydroxy group. Products containing such end groups may be obtained by incorporating an appropriate primary or secondary monoamine such as di-n-butylamine or dimethylamine as one of the constituents of the oxidative coupling reaction mixture. Also frequently present are 4-hydroxybiphenyl end groups, typically obtained from reaction mixtures in which a by-product diphenoquinone is present, especially in a copper-halide-secondary or tertiary amine system. A substantial proportion of the polymer molecules, typically constituting as much as about 90% by weight of the polymer, may contain at least one of said aminoalkyl-containing and 4-hydroxybiphenyl end groups.
It will be apparent to those skilled in the art from the foregoing that the contemplated poly(arylene ether) include all those presently known, irrespective of variations in structural units or ancillary chemical features. Poly(arylene ether) resin is present in about 5 weight percent (wt %) to 95 wt % based on the weight of the composition, preferably about 30 wt % to about 60 wt % based on the weight of the composition.
The term polystyrene as used herein includes polymers prepared by methods known in the art including bulk, suspension and emulsion polymerization, which contain at least 25% by weight of structural units derived from a monomer of formula (II)
wherein R8 is hydrogen, lower alkyl or halogen; Z1 is vinyl, halogen or lower alkyl; and p is from 0 to about 5. These resins include homopolymers of styrene, chlorostyrene and vinyltoluene, random copolymers of styrene with one or more monomers illustrated by acrylonitrile, butadiene, alpha-methylstyrene, ethylvinylbenzene, divinylbenzene and maleic anhydride, and rubber-modified polystyrene resins comprising blends and grafts, wherein the rubber is a polybutadiene or a rubbery copolymer of about 98-70% styrene and about 2-30% diene monomer. Polystyrene resins are known to be miscible with poly(arylene ether) resin in all proportions, and any such blend may contain polystyrene resin in amounts of about 5 wt % to about 95 wt % and preferably about 40 wt % to about 70 wt %, based on the weight of the composition.
Suitable non-halogenated flame retardants are organic phosphates, preferably an aromatic phosphate compound of the formula (III):
where R is the same or different and is alkyl, cycloalkyl, aryl, alkyl substituted aryl, halogen substituted aryl, aryl substituted alkyl, halogen, or a combination of any of the foregoing, provided at least one R is aryl.
Examples include phenyl bisdodecyl phosphate, phenylbisneopentyl phosphate, phenyl-bis (3,5,5xe2x80x2-tri-methyl-hexyl phosphate), ethyldiphenyl phosphate, 2-ethyl-hexyldi(p-tolyl) phosphate, bis-(2-ethylhexyl) p-tolylphosphate, tritolyl phosphate, bis-(2-ethylhexyl) phenyl phosphate, tri-(nonylphenyl) phosphate, di (dodecyl) p-tolyl phosphate, tricresyl phosphate, triphenyl phosphate, dibutylphenyl phosphate, 2-chloroethyldiphenyl phosphate, p-tolyl bis(2,5,5xe2x80x2-trimethylhexyl) phosphate, 2-ethylhexyldiphenyl phosphate, and the like. The preferred phosphates are those in which each R is aryl.
Alternatively, the organic phosphate can be a di- or polyfunctional compound or polymer having the formula (IV), (V), or (VI) below:
including mixtures comprising at least one of the foregoing compounds, in which R1, R3 and R5 are, independently, hydrocarbon; R2, R4, R6 and R7 are, independently, hydrocarbon or hydrocarbonoxy; X1, X2 and X3 are halogen; m and r are 0 or integers from 1 to 4, and n and p are from 1 to 30.
Examples include the bis diphenyl phosphates of resorcinol, hydroquinone and bisphenol-A, respectively, or their polymeric counterparts.
Methods for the preparation of the aforementioned di- and polyfunctional aromatic phosphates are described in British Patent No. 2,043,083.
Another development is the use of certain cyclic phosphates, for example, diphenyl pentaerythritol diphosphate, as a flame retardant agent for polyphenylene ether resins, as is described by Axelrod in U.S. Pat. No. 4,254,775.
Also suitable as flame-retardant additives are compounds containing phosphorus-nitrogen bonds, such as phosphonitrilic chloride, phosphorus ester amides, phosphoric acid amides, phosphonic acid amides, phosphinic acid amides, tris(aziridinyl) phosphine oxide, or tetrakis(hydroxymethyl) phosphonium chloride.
Preferred phosphate flame retardants include those based upon resorcinol such as, for example, resorcinol tetraphenyl diphosphate, as well as those based upon bis-phenols such as, for example, bis-phenol A tetraphenyl diphosphate. Phosphates containing substituted phenyl groups are also preferred. In an especially preferred embodiment, the organophosphate is butylated triphenyl phosphate ester, resorcinol tetraphenyl diphosphate, bis-phenol A tetraphenyl diphosphate, or a mixture comprising at least one of the foregoing.
The flame retardant is present in an amount sufficient to impart a degree of flame retardancy to the composition to achieve a HBF rating in the UL ASTM D 4986/ISO/DIS 9772.3 test for 12 mm thickness bars. The particular amount will vary, depending on the molecular weight of the organic phosphate, the amount of the flammable resin present and possibly other normally flammable ingredients that might also be included in the composition. Typically the amount of flame retardant is in the range of about 2 wt % to about 25 wt % and preferably about 5 wt % to about 20 wt % based on the weight of the composition.
In general, useful blowing agents are volatile liquids and include but are not limited to aliphatic hydrocarbons, straight chain or branched, with up to 10 carbons; ketones such as acetone and methylethylketone; short chain alcohols such as alcohols having up to 10 carbons; and cycloaliphatic hydrocarbons. Preferred blowing agents are all pentane isomers and mixtures of pentane isomers. An especially preferred blowing agent is n-pentane. Blowing agents are typically used in amounts of about 2 wt % to about 20 wt % based on the weight of the composition, with about 2 wt % to about 10 wt % preferred based on the weight of the composition.
Particularly suitable impact modifiers are the so called block copolymers, for example, A-B-A triblock copolymers and A-B diblock copolymers. The A-B and A-B-A type block copolymer rubber additives which may be used are thermoplastic rubbers comprised of one or two alkenyl aromatic blocks which are typically styrene blocks and a rubber block, e.g., a butadiene block which may be partially hydrogenated. Mixtures of these triblock copolymers and diblock copolymers are especially useful. All impact modifiers generally used for compositions comprising a poly(arylene ether) resin, a polystyrene or a combination of a poly(arylene ether) resin and a polystyrene can be used.
Suitable A-B and A-B-A type block copolymers are disclosed in, for example, U.S. Pat. Nos. 3,078,254, 3,402,159, 3,297,793, 3,265,765, and 3,594,452 and U.K. Patent 1,264,741. Examples of typical species of A-B and A-B-A block copolymers include polystyrene-polybutadiene (SBR), polystyrene-poly(ethylene-propylene), polystyrene-polyisoprene, poly(xcex1-methylstyrene)-polybutadiene, polystyrene-polybutadiene-polystyrene (SBS), polystyrene-poly(ethylene-propylene)-polystyrene, polystyrene-polyisoprene-polystyrene and poly(xcex1-methylstyrene)-polybutadiene-poly(xcex1-methylstyrene), as well as the hydrogenated versions thereof, and the like. Mixtures comprising at least one of the aforementioned block copolymers are also useful. Such A-B and A-B-A block copolymers are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE, Shell Chemical Co., under the trademark KRATON, Dexco under the tradename VECTOR, and Kuraray under the trademark SEPTON.
A useful amount of impact modifier is up to about 30 wt % based on the weight of the composition, with about 5 wt % to about 15 wt % based on the weight of the composition preferred. In an especially preferred embodiment, the impact modifier comprises a polystyrene-polybutadiene-polystyrene block copolymer.
Non-halogenated, fire retardant, expandable poly(arylene ether)/polystyrene blends can also include effective amounts of at least one additive selected. Possible additives include anti-oxidants; drip retardants; coating additives; dyes; pigments; colorants; nucleating agents; stabilizers; small particle minerals such as clay, mica, and talc; antistatic agents; plasticizers, lubricants; mold release agents; and mixtures comprising at least one of the foregoing additives. Effective amounts of the additives vary widely, but they are usually present in an amount up to about 50% or more by weight, based on the weight of the entire composition.
The non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blends are formed by intimately mixing poly(arylene ether) resin, polystyrene resin, and optional impact modifier in melt with a non-halogenated fire retardant. Preferably the poly(arylene ether) resin, polystyrene resin, and optional impact modifier are melted and mixed and the non-halogenated fire retardant is then added and intimately mixed to form a fire retardant mixture. All mixing equipment capable of mixing in melt may be used although an extruder is preferred. Use of an extruder for the formation of the fire retardant mixture appears to enhance the distribution of the non-halogenated fire retardant. Without being bound by theory, it is believed that even distribution of the non-halogenated fire retardant allows the non-halogenated, fire retardant, expandable mixture to achieve an HBF rating in the UL ASTM D 4986/ISO/DIS 9772.3 flammability test. The fire retardant poly(arylene ether)/polystyrene mixture is then mixed in melt with a blowing agent, preferably in a tandem extruder, and cooled. Use of a tandem extruder for melt mixing the fire retardant mixture with the blowing agent to form the non-halogenated, fire retardant, expandable poly (arylene ether)/polystyrene blend allows the melt mixing to occur in extruder A of the tandem extruder and cooling of the blend to occur in extruder B of the tandem extruder thereby preventing premature devolatization of the blowing agent at the extruder die.
The invention is further illustrated by the following non-limiting examples.

Preparation of flame retardant expandable poly(arylene ether)/polystyrene compositions


A laser alignment system is provided. The system includes a plurality of lasers which are sequentially operative for producing first and second laser beams that are parallel to one another. The system further includes a target assembly. The target assembly includes lenses and mirrors disposed such that the first laser beam impinges directly on the target to provide displacement data. The second laser beam is focused and reflected so that the focal point of the reflected second beam impinges on the target. In a similar manner, a third parallel beam may be provided and may be focused to impinge on the target. Additionally, the plural laser beams may be substituted for by a single laser plane. The second and/or third beams provide alignment data, while the first beam provides displacement data.

1. Field of the Invention
The subject invention relates to a laser alignment system which comprises a plurality of lasers, a target and a computer for controlling operation of the lasers and for analyzing signals produced by the target for determining spatial location and angular/slope data.
2. Description of the Related Art
Many manufacturing processes require the alignment of a plurality of parts that are spaced from one another. For example, a rotating tool may require a specified alignment to a workpiece for boring a hole in the workpiece or for taping threads into a previously bored hole. In other situations, arrays of rotors or stators must be precisely aligned to the axis of a turbine. In still other situations, sheaves or pulleys of a machine tool should be mounted to rotational axes that are precisely parallel to one another, at specified distances and with the sheaves in a common plane. Other manufacturing processes require parts to be assembled at specified positions relative to reference planes. For example, seats and storage bins on large aircraft should be accurately positioned relative to horizontal and vertically aligned planes extending along the length of the aircraft.
Historically, most of the above-described alignment has been carried out with purely mechanical devices, such as bubble levels, or by purely optical devices, such as sight gages. However, a very effective prior art apparatus for checking alignment includes a laser emitter and a photosensitive target. The laser emitter produces a perfectly straight beam that is not affected by gravity. The target is operative to generate signals that identify the center of energy of the laser beam impinging on the target. The target of the prior art laser alignment system typically is connected to a computer which calculates certain displacement and angular alignment information based on the signals produced by the target. This prior art system is used by mounting the laser to a fixed location and by mounting the target to a specified location on a part that must be aligned. A very simple but effective apparatus for aligning a rotating tool to a master part or workpiece is disclosed in U.S. Pat. No. 4,566,202 which is assigned to the assignee of the subject invention.
Some prior art laser apparatus include a penta-prism which is operative to receive an input laser beam and to reflect that input laser beam through precisely 90xc2x0. The penta-prism then may be rotated about the axis defined by the input laser beam. Thus, the output laser beam effectively sweeps a flat laser plane that is perpendicular to the input laser beam. The plane produced by the rotating laser defines a frame of reference. A plurality of targets then may be positioned in the reference plane, and the locations of those targets can be measured precisely relative to the reference plane. A laser apparatus with a rotating penta-prism for sweeping a flat optical plane is shown in U.S. Pat. No. 4,297,031 which is assigned to the assignee of the subject invention. U.S. Pat. No. 4,297,031 also shows the above-referenced plurality of photosensitive targets mounted at locations to be impinged upon by the rotating output laser.
The assignee of the subject invention also is the owner of U.S. Pat. No. 5,307,368 which is directed to an apparatus for simultaneously generating a plurality of mutually perpendicular planes. The device shown in U.S. Pat. No. 5,307,368 enables targets to be placed in each of the mutually perpendicular planes for positioning an object relative to those planes.
The above-described prior art laser alignment systems typically employ a plurality of targets for defining position and alignment relative to at least one plane swept by at least one rotating output laser beam. For example, a plurality of photosensitive target cells have been used in the prior art to assess both displacement and angular misalignment.
In recent years, low cost, low accuracy laser alignment systems have entered the market. The availability of a lower cost, albeit poorer quality, laser alignment system has created a market pressure to decrease the cost for the high quality laser alignment systems. During this same time span, the cost of photosensitive target cells has remained high, and in some instances has increased. Hence, the cost for photosensitive targets in a laser alignment system that requires plural targets limits the ability to respond to market pressures for lower cost alternatives without sacrificing accuracy or the quality of workmanship. Simultaneously, however, the cost of lasers has decreased significantly.
In view of the above, it is an object of the subject invention to provide a low cost, high quality laser alignment system.
Another object of the subject invention is to provide a laser alignment system that enables an assessment of displacement and angular alignment errors with a single target.
A further object of the subject invention is to provide a laser alignment system with plural laser beams and a single target for assessing displacement and angular alignment.
The subject invention is directed to a laser alignment system comprising a plurality of lasers and a light and position-sensitive target cell. A control system may be provided for turning the lasers on and off sequentially. Thus, the single light and position-sensitive target cell is operative to sequentially generate signals indicative of locations at which the respective laser beams impinge upon the target cell. The control system may further be connected to the target cell for receiving signals produced by the target cell and for analyzing the signals to provide position and alignment information.
The system of the subject invention may include first and second lasers and a beam splitter. The beam splitter may be positioned in proximity to the single light and position-sensitive target cell. In particular, the beam splitter may be disposed such that a first beam produced by the first laser passes through the beam splitter and impinges upon the target cell. As the target cell is moved relative to the first beam, vertical and horizontal position signals are generated. The second laser produces a second beam that is aligned generally parallel to the first beam. The system further includes a mirror disposed to align with the second beam. The mirror reflects the beam to the beam splitter which further reflects the beam onto the light and position-sensitive target cell. Additionally, the system may include a lens disposed between the source of the second beam and the mirror. Thus, the second beam is focused by the lens and is directed toward the mirror. The combined optical distance from the lens to the mirror, from the mirror to the beam splitter and from the beam splitter to the target cell is selected to substantially equal the focal length of the lens. Thus, the second beam will substantially focus on the single light and position-sensitive cell in the target assembly.
When the first laser is turned on, the first beam acts as a position measuring device that generates X-axis and Y-axis (horizontal and vertical) position signals to indicate displacement of the target assembly relative to the incoming first laser beam. When the second laser is turned on, the target acts as an angle or slope sensitive target in both pitch and yaw. Additional readings of the cell are taken a short time after each of the center or angle readings. These readings constitute background light readings and are subtracted from the respective readings when the laser is on. The result is a compensation for the background light that is also falling on the target cell.
An alternate embodiment of this invention includes a lens, a quarter wave plate, a mirror and first and second lasers. The first laser produces a first beam that passes straight through the lens. The lens starts to focus the beam on the cell. The second laser produces a second laser beam that is parallel to or off-axis relative to the first beam. The second beam passes through the lens, hits the mirror, reflects back to the polarizing beam splitter coating on the back of the lens and further reflects to focus on the cell. The second beam is the angle beam and the combination of the lens, the mirror and the polarizing beam splitter coating constitutes a system that ends up focusing the second beam on the surface of the target cell. This combination acts as a collimator. The cell cooperates with the second beam to measure the angle of the target axis relative to the second beam. The first beam, on the other hand, goes straight through the lens and is partially focused. The first beam and the cell act as a center measuring device and provides signals indicative of X-axis and Y-axis (horizontal and vertical) position or displacement. If the target is moved laterally or perpendicular to the first beam, then position information is read from the target cell substantially as in prior art targets. The problem with the system as described above is that the partial focusing means also is partially sensitive to angle. A conventional target with no lens measures center, but is not sensitive to angle. However, in the subject invention, due to the fact that angle is measured, the center reading can be corrected for any angle.
The primary advantage of this latter embodiment is that the combination of the first beam and the lens of the cell act such that spot size is reduced in diameter. This effectively increases the cell size, and hence the range of measurement is increased. The amount of the increase is proportional to the ratio of the focal length of the lens divided by the distance from the nodal point of the lens to the surface of the cell. As noted above, position sensitive target cells can be expensive, especially for larger sizes. Smaller cells, however, are relatively inexpensive. Thus, an advantage of the system described above is that a small cell can behave as if it were physically much larger by the ratio of the two distances, as long as resolution is adequate. Thus, the above-described combination uses a very economical method of achieving larger measurement ranges.
The second beam is focused onto the photosensitive target, as described above. In particular, the lens of the above-described system is a piano-concave lens with a polarizing sensitive 50%xe2x80x9450% beam splitter coating on the plane or flat side of the lens. A polarizing sensitive coating will transmit almost 100% of P polarization and almost totally reflect S polarization. The plane of polarization of both the first and second beams are rotated so that approximately 100% of their light is transmitted. In this embodiment, a quarter wave plate is aluminum, Al, coated on the back to form a mangrin mirror. A quarter wave plate will take a plane polarized beam and turn it into a circularly polarized beam. Upon reflection, the beam will change xe2x80x9chandxe2x80x9d from right circularly polarized to left hand. As the second beam passes again through the quarter wave plate, it is changed from circularly polarized light back to linear, but is rotated 90xc2x0. The second beam then reflects 100% off the back of the lens and focuses on the lens.

Laser alignment system with plural lasers for impingement on a single target


This invention provides a new class of squaraine dyes having moieties which serve for the covalent attachment to biological substrates and resulting in the fluorescent labeling of the substrates. The labeled substrates are intended for use in analytical techniques for the detection and measurement of biological and clinical compounds of interest.

1) Field of the Invention
Functionalized dyes bearing moieties for the attachment to biological substrates are very important, serving in the detection of disease in biological fluids and the detection of a variety of analytes such as environmental contaminants and toxins in food.
This invention relates to a new class of squaraine dyes which are equipped with functionalities serving in the covalent attachment of these dyes to biological substrates forming conjugates resulting in the fluorescent labeling of the substrate.
The novel compounds are intended for use in analytical techniques for the detection and measurement of biological and clinical compounds of interest. Typical examples of such compounds are bacteria, viruses, enzymes, hormones, antibodies, proteins, derivatized oxy and deoxy polynucleic acids, drugs and other materials.
2) Description of the Prior Art
Squaraine dyes are known in the art as compounds derived by reaction of squaric acid and aromatic nucleophiles. Structural and physical chemical characteristics of squaraine dyes are described by Sprenger, et al in Angew chem. 80, 541 (1968). The type of squaraine dyes thereof having the aromatic nucleus directly attached to the squaric moiety have been known for quite some time and their use as photosensitizers, photoconductive devices and in the labeling of red blood cells has been reported. None of these dyes however has been covalently coupled to biological substrates nor have any of these dyes been, in actuality, made with functional groups which allow for the covalent coupling to substrates of interest. Accordingly, it is an object of the present invention to provide novel derivatives of squaraine dyes which may be readily coupled to compounds of clinical or biological interest to provide conjugates which exhibit intense fluorescence. A further object of the invention lies in the coupling of the novel dyes to form adducts with a broad spectre of biological and clinical compounds by facile and gentle chemical reactions. Other objects and advantages of the present invention will become apparent from the following detailed description of the invention.
While the invention is susceptible to various modifications and alternative forms, there will herein be described in detail the preferred embodiments. It is not intended to limit the invention to the specific forms disclosed. On the contrary, it is intended to cover all modifications and alternative forms falling within the spirit and scope of the invention as expressed in the appended claims.
The present invention is directed to novel derivatives of squaraine dyes which contain moieties which allow for the covalent coupling of these dyes to a variety of biological substrates and other organic molecules. The resulting conjugates provide intense fluorescent haptens, antigens, drugs, antibodies, peptides, enzymes, oxy and deoxy polynucleic acids which can be used in the development of fluorescent analytical techniques. The basic structure of the functionalized squaraine dyes is structurally represented by the formula I.
wherein R1 is a lower carboxyalkyl (1-7 carbon atoms); R2 is hydrogen, a lower alkyl group (1-7 carbon atoms); a lower alkyl 1-7 carbon atoms and which may be substituted with groups selected from xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94COOH and xe2x80x94NHSO3H; R3 is a lower alkyl (1-5 carbon atoms), lower carboxyalkyl (1-7 carbon atoms) or a lower alkyl group 1-7 carbon atoms containing substituents selected from the group consisting of xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94COOH; and xe2x80x94NHSO3H); R4 is hydrogen, (alkyl 1-5 carbon atoms, or lower alkyl 1-7 carbon atoms which may be substituted with groups selected from xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94COOH and xe2x80x94NHSO3H).
Two examples representing I by structural formula are shown in II and III:
The squaraine dyes of the invention represented structurally in I
wherein R1 is a lower carboxyalkyl (1-7 carbon atoms), R2 is hydrogen, an alkyl group (1-7 carbon atoms), a lower alkyl group (1-7 carbon atoms) which may be substituted with groups selected from xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94COOH and xe2x80x94NHSO3H; R3 is a lower alkyl (1-5 carbon atoms), a lower carboxyalkyl (1-7 carbon atoms) or a lower alkyl group (1-7 carbon atoms) containing substituents selected from the group consisting of xe2x80x94SO3H, xe2x80x94PO3H2 and xe2x80x94NHSO3H; R4 is hydrogen, alkyl (1-5 carbon atoms) or a lower alkyl (1-7 carbon atoms) which may be substituted with groups selected from xe2x80x94SO3H, xe2x80x94PO3H2, COOH and xe2x80x94NHSO3H;
are ideal fluorescent agents due to their attractive fluorescent emissions exhibited at wavelengths above 580 nanometers. The carboxyalkyl group in the R1 or R3 moieties provide an active hydrogen bonding site and functions most suitably to promote coupling of the dye with organic substrates of interest.
The squaraine dyes of the invention were synthesized using known techniques. The symmetrical dyes, where R1 and R2 are the same as R3 and R4, were prepared by reacting the aromatic nucleophiles with squaric acid in the presence of a polar aprotic solvent and a conventional solvent. A one to one mixture of n-butanol and benzene or toluene, is the solvent system previously applied, although a solvent such as methanol or ethanol can be used as well. For the preparations of the unsymmetrical squaraine dyes where R1 and R2 are different from R3 and R4, the method described by Joseph R. Lukowicz in xe2x80x9cDyes and Pigmentsxe2x80x9d 21(1993), 227-234, was applied. Details of this method utilizing two different aromatic nucleophiles and 3,4-diethoxy-cyclobutanedione will become apparent in the experimental section.
The squaraine dyes of the invention may be reacted with any compound of interest capable, of course, of reacting with the carboxyalkyl group. For example, any compound containing (in the classical sense) an active hydrogen group may be coupled to the carboxyalkyl of the squaraine dyes, e.g. any compound containing a hydroxyl or an amino group with active hydrogen can be utilized. Accordingly, a wide number of amino acids, peptides, proteins, enzymes, drugs, pesticides, derivatized oxy and deoxy polynucleotides and nucleotides, various natural products, plant and animal hormones, polyamines, viruses, bacterial cells and other metabolites contain groups reactive with the carboxylic group can be employed.
The squaraine dyes of the invention can be covalently bound to organic substrates through the carboxyalkyl group by utilizing known process conditions. It is suitable to activate the dye containing the carboxylic group with a carbodiimide, e.g. cyclohexyl carbodiimide or the water soluble carbodiimide known in the art as EDC, in a polar solvent such as dimethylformamide, dimethylsulfoxide or in aqueous buffers. After the activation, the solution containing the dye is added to the solution containing the substrate. Proteinecious substrates are usually dissolved in aqueous buffered solutions, non-proteinecious substrates can be dissolved in a variety of solvents which are inert to the reaction partners such as dimethylformamide, dimethylsulfoxide, pyridine and other solvents including aqueous buffered solutions. Another method adapted in the coupling of carboxylic moieties to organic molecules containing active hydrogen groups is utilizing a succinimide activated ester of the carboxylic group. The succinimidyl ester of carboxylic-containing molecules can be prepared and isolated prior to coupling to the substrates, or made in situ and used in further couplings without isolation.
Thus, in accordance with the present invention, conjugates of carboxylic derivatives of squaraine dyes and organic substrates can be illustrated by the following formula:
wherein n=1-6; R2, R3 and R4 are the same as defined above; Y is oxygen, primary or secondary amino group; and L is an organic substrate containing a functional group consisting of amino or hydroxyl.
The coupling of the dyes was carried out in a variety of solvents depending on the nature of the amine-substrate or the hydroxyl-substrate. The coupling of proteins was carried out in a variety of buffers, such as carbonates, phosphates or MES using the carbodiimide technique or the succinate ester. The PH of the reaction ranged from 1-12, but a PH of 5-10 was preferred. The reaction time and temperature was appropriately selected depending on the stability and nature of the protein. The preferred reaction time was 1 to 24 hours and the preferred temperature was 4xc2x0 C. to ambient. The coupling to oligonucleotides was carried out in carbonate or phosphate buffers PH-8 or directly in pyridine-DMF solvent mixture with the succinimidyl ester of the dye made in situ in DMF solution. Details of these and couplings to other substrates will become apparent in the experimental section of this invention.
Conjugates of carboxyalkyl derivatives of squaraine dyes with organic substrates of interest are intended for use in many of the several known techniques involving fluorescent tagging or fluorescent competitive binding to detect and measure a compound or analyte of interest. The particular conjugates used will be dependent upon the type of tagging required by the technique of choice and the technique selected will be determined by the results as required. The squaraine conjugates of this invention are particularly advantageous since they exhibit little deleterious effects on the biological compounds and emit at wavelengths which are above 580 nanometers.
Specific examples of compounds represented by formula I are:

Fluorescent dyes for the labeling of biological substrates


A product tag system comprises: an RFID tag adapted for attachment to a product; a data store in the tag for bar code information relating to the product; a tag detacher for removing the tag from the product at a point of sale; an RFID tag reader for retrieving the bar code information from the tag when the tag is placed in the tag detacher; and, an display for presenting the bar code information in a form which can be scanned by a conventional bar code scanner, and/or in human readable form. A method for monitoring products comprise the steps of: attaching an RFID tag to a product; writing bar code information onto the tag; retrieving the bar code information from the tag at a point of sale; displaying the bar code information in a form which can be scanned by a conventional bar code scanner, and/or in human readable form; and, detaching the tag from the product.

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1. Field of the Invention
This invention relates to the fields of product scanning and product tracking, and in particular, to a product tag system integrating an enhanced wireless reader with a bar code scanner.
2. Description of the Related Art
A wireless communication transponder, for example a radio frequency identification (RFID) tag, can provide the ability to store and update information within an internal storage element and can be associated with a product starting at its manufacturing origins. This transponder can be used and reused throughout manufacturing, distribution and the retail processing of the product. These transponders are already provided with EAS elements, and are further able to store encoded bar code information.
At a point of sale (POS), for example, the transponder can be scanned to retrieve the stored information. However, a bar-code scanner can be present, and indeed is likely to be present, which interfaces to the cash register and the retail system. An item or product needs to be scanned by the bar code reader as well, to complete a transaction.
As an alternative, an RFID reader can be interfaced to the cash register, eliminating the bar code scanner interface. This approach lacks practicality because bar code scanning may be necessary on many items that lack RFID tags. Another alternative is to employ both a bar code scanner and an RFID reader. This approach requires cabling software and other changes to accommodate both systems, which makes the hardware more expensive to manufacture and install. Moreover, two operations would then be necessary for each sold product, namely bar code scanning and RFID reading, thus slowing check-out. The detection of an electronic article surveillance (EAS) element is usually implemented at an exit door, and accordingly, this aspect of wireless communication has not before interfered with bar code scanning.
Bar code readers are only capable of providing pre-defined information according to their predetermined markings, namely bars. EAS protection is provided by a separate tag. Further, an article would need a third tag for RFID functionality. Such a combination can be expected to hinder, rather than promote efficiency for point of sale operations. Any solution must compliment the existing bar code applications and not adversely affect the productivity of the bar code application.
Accordingly, there is a long-felt need to merge the bar code scanning, wireless communication and EAS technologies for the purpose of providing a total solution that integrates bar code scanners with wireless communication and EAS protection.
The inventive arrangements satisfy the long-felt need for integration by employing a wireless communication system and an EAS device in conjunction with a bar-code scanner to provide complete POS operation. These elements are advantageously integrated into an apparatus that provides EAS protection and RFID functionality for a system already having a bar code reader.
The inventive arrangements provide in a compact form a facility for the interrogation of items employing bar codes, wireless transponders and EAS protection. The design is advantageously compact for applications with limited space and where the bar code scanner is mobile.
The inventive arrangements advantageously facilitate interfacing an RFID reader with a bar-code scanner by using a display. The display conveys the bar code information residing in the RFID component to the bar code reader. This approach minimizes installation requirements and provides RFID functionality to bar code systems. Compatibility between RFID and any bar-code scanner and associated POS station is possible due to the optical bar-code interface to the display, i.e., there are no wired connections.
A product tag system, in accordance with the inventive arrangements, includes: an RFID tag adapted for attachment to a product; at least one data store in the tag for bar code information relating to the product, which is typically a UPC code, but could be other bar coded data; a tag detacher for removing the tag from the product at a point of sale; an RFID tag reader for retrieving the bar code information from the tag when the tag is placed in the tag detacher; and, a display for presenting the bar code information in a form which can be scanned by a conventional bar code scanner. The tag can further include a detectable EAS element.
The tag detacher is advantageously inoperable for detaching the tag until the bar code information has been read, or alternatively, until the tag detacher receives a confirmation signal that the bar code information has been successfully read by the bar code scanner. In this event, the tag detacher can receive a confirmation signal that the bar code information has been successfully read by the bar code scanner, the tag being detached, for example automatically, in response to the confirmation signal.
The tag can advantageously include a further data store for further product information. The further information can be, for example but not limited to, one or more of product price, product size, SKU number, product identity such as model and serial number, manufacture date and location, and the like.
The tag detacher and the RFID tag reader can be integrated in a single housing, the tag detacher and the display can be integrated in a single housing or the tag detacher, the RFID tag reader and the display can be integrated in a single housing. The single housing can be adapted for mounting in a fixed position with respect to the conventional bar code scanner. Alternatively, the display itself can be adapted for mounting in a fixed position with respect to the conventional bar code scanner.
The system can further comprise an RFID writer. In this case, the tag includes a further data store for receiving from the RFID writer information regarding the sale of the product, wherein the product sale information is available for subsequent use.
The system can further include: a hand-held RFID reader adapted for attachment to a hand-held bar code scanner; a display on the hand-held RFID reader, the display being in an aligned position when the reader and the scanner are attached for presenting the bar code information in a form which can be scanned by the hand-held bar code scanner; and, a tag detacher remote from the reader for detaching the tag after the displayed bar code is scanned. The tag detacher can automatically detach the tag responsive to a signal transmitted by the reader.
A method for monitoring products, in accordance with the inventive arrangements, includes the steps of: attaching an RFID tag to a product; writing bar code information onto the tag; retrieving the bar code information from the tag at a point of sale; displaying the bar code information in a form which can be scanned by a conventional bar code scanner at the point of sale; and, detaching the tag from the product. The attaching and writing steps can occur in any order. Moreover, the attaching, writing and activating steps can occur in any order.
The method can further include the step of activating a detectable EAS element in the tag prior to the retrieving step.
The method further includes the step of detaching the tag only after the bar code information has been read by the conventional bar code scanner.
The method can include the step of performing the retrieving, displaying and detaching steps with components disposed in a single housing. In this case, the method can further include the step of disposing the housing in a fixed position relative to the conventional bar code scanner.
The writing step can include also writing onto the tag at least one of: price information, size information, SKU number, manufacture date and location, and the like.
The method can further include the step of writing to the tag, at the point of sale, information regarding the sale of the product, whereby the product sale information is available for subsequent use.
Objectives, advantages, and applications of the present invention will be made apparent by the following detailed description of embodiments of the invention.

RFID reader with integrated display for use in a product tag system


A beehive frame comprising two congruent pieces of molded plastic each having a plurality of openings therein of equal size and shape. The two members are placed in facing relation with the openings in registration and a sheet of comb foundation, such as natural beeswax, supported between the openings. The two pieces are of molded plastic, preferably an expanded polystyrene, and are formed by cutting a unitary plastic part lengthwise with a hot wire. The frame normally includes a plurality of openings for the construction of combs, each surrounded by structure which may be cut from the remainder of the frame as desired to provide one or more individual honeycombs. The plastic is preferably of a brown shade for esthetic purposes so that "travel marks" made by the bees upon the frame surrounding the combs are less noticeable. The frames are extremely economical in materials and construction time, being disposable after a single use.

The present invention relates to bee frames used in the production of comb honey and, more particularly, to novel molded plastic frames and methods of construction thereof.
A typical beehive maintained for the domestic consumption of comb honey includes a number of so-called bee frames supported in side-by-side relation within a rectangular box or housing, referred to as a super, two or more such supers normally being stacked upon one another to form the complete hive. The bee frames have traditionally been constructed of wood in an open rectangular configuration, but frames of molded plastic construction have also been proposed. U.S. Pat. Nos. 3,579,676, 2,239,708, 3,088,135, 3,864,196 and 3,885,260, for example, disclose beehive frames and/or comb foundations made partially or completely of molded plastic. The structure of these prior art molded plastic frames is such, however, that expensive molds are required and/or other disadvantages of wooden bee frames remain.
A principal object of the present invention is to provide a beehive frame, and method of construction thereof, which significantly reduce the cost of both labor and materials to the point that the frames are disposable after a single use without significantly affecting the cost of the comb honey contained therein.
A further object is to provide a bee frame which may conveniently be cut into individual pieces after being filled with comb honey to serve as a support for the marketed combs.
Another object is to reduce the cost and/or increase the profit to the producer of comb honey by providing a bee frame which requires minimal assembly time, allows the honey to be sold without cutting the comb, provides the quantity requested by the customer in a single operation, and provides an attractive and ready-made package for the honeycomb.
Other objects will in part be obvious and will in part appear hereinafter.

Beehive frame and method of construction thereof