An in-mold primer coating adapted to be applied in-mold to a thermoplastic substrate and heat cured to form a thermoset surface coating on the molded substrate. The in-mold primer coating comprises a coreactive polymerizable composition comprising an epoxy-acrylate oligomer having a molecular weight from about 350 to about 2500, a hydroxyl functional acrylate or methacrylate, a vinyl aromatic monomer such as styrene, and a small amount of acrylic or methacrylic acid, with the balance being other diacrylate and/or other ethylenically unsaturated monomer(s), if any.

The invention pertains to in-mold coatings for thermoplastic substrates and more particularly to reactive epoxy-acrylates copolymerizable with other ethylenically unsaturated components to provide a thermosetting in-mold primer coating for thermoplastic substrates including polycarbonates and polycarbonate alloy substrates.
Thermoplastic substrates ordinarily are based on converting thermoplastic resins, powders, granules, pellets and similar forms of thermoplastic resinous material under heat and pressure to form useful molded articles. Injection molding processes for molding thermoplastic resinous materials typically comprise heating the molding compound to form a viscous flowable melt, injecting the heated melt under high pressure into a relatively cool closed mold cavity, cooling the melt to form a solid shape molded substrate conforming to the interior configuration of the mold cavity, and then ejecting the molded part from the mold cavity. Thermoplastic compression molding ordinarily comprises thermoplastic resin compounded with fillers, colorants, lubricant and other processing additives to form granular or palletized thermoplastic particles known as molding powder. On the application of heat and pressure, the compounded molding resin flows under pressure into a heated mold to conform to the shape of the mold cavity. The mold is closed and the heat and pressure is maintained for sufficient dwell time to fully form the intended plastic article. The mold and formed plastic article are cooled to harden the molded plastic article, whereupon the mold can be opened and the molded article removed. In thermoplastic molding processes, the molded part can be a finished article having many design details such as bosses, flanges, ribs, bushings, holes or other openings, various functional structures, decorative designs, and flat surfaces. Most molded substrates need to be painted and need to obtain good adhesion to the applied surface coating. However, many desirable decorative or other finish surface coatings are difficult to adhere directly to thermoplastic substrates, especially polycarbonates and polycarbonate alloy plastics. Paint adhesion to molded thermoplastic substrates is frequently difficult to obtain with an applied finished top surface coating and invariably requires an intermediate primer coating to achieve the necessary adhesion with the particular thermoplastic substrate. The primer coating must provide adhesion to the substrate as well as interface adhesion with the finished surface coatings. Thus, for various reasons, an in-mold primer coating is often used in injection molding of thermoplastics to enable subsequent adhesion of a wide variety of surface top coatings regardless of the substrate thermoplastic resin composition. It is particularly difficult to obtain adhesion with surface coatings on thermoplastic polycarbonates and polycarbonate plastic alloys.
In-mold coatings typically are sprayed into the mold cavity to coat the interior mold surfaces during the molding process to provide a primer surface coating integrally fused or adhered to the thermoplastic substrate being molded. In-mold coatings have been found to be particularly advantageous for molded parts or articles to provide a functional surface coating similar to post-mold process such as paint, as well as avoid surface imperfections in the molded part such as surface porosity, sink marks, surface waviness, and similar surface defects and imperfections which frequently require additional labor and costs to rework and post finish such moldings. In addition, in-mold primer coatings must provide adhesion to the substrate along with interface adhesion with most any type of finish surface coating. In-mold coatings can be injected into a slightly opened mold, or under pressure into a closed mold, where the in-mold coating is applied to the mold cavity surfaces and/or applied over a molded or partially molded substrate, and then cured under heat and pressure in the mold cavity to form an integral thermoset cured surface coating on the molded substrate. An in-mold coating can be injected into the mold after the mold pressure is released or while the mold is opened infinitesimally to permit injection of the in-mold coating into the mold cavity. For instance, U.S. Pat. No. 5,902,534 discloses a method of injecting molding resin into a mold, followed by injecting an in-mold coating into the mold cavity between the molded substrate and the mold cavity surfaces, then compressing and curing the in-mold coating while in contact with the mold cavity surface, and then cooling the molded substrate to provide interface adherence of the cured in-mold coating to the molded substrate surface. Similarly, U.S. Pat. No. 4,668,460 suggests a method of in-mold coating a molded substrate contained within a closed mold by first molding the substrate under pressure and then injecting an in-mold coating into the closed mold at a pressure higher than the molding pressure. In-mold coatings are primarily directed to producing smooth surfaces free of surface defects and imperfections, while in-mold primer coatings additionally provide good adhesion to the specific thermoplastic substrate and an adherent surface for the subsequently applied surface topcoat.
In-mold polymeric epoxy acrylate coatings containing copolymerizable epoxy acrylates and/or ethylenically unsaturated monomers are disclosed in U.S. Pat. No. 4,414,173, U.S. Pat. No. 4,508,785, U.S. Pat. No. 4,515,710, U.S. Pat. No. 4,534,888, U.S. Pat. No. 5,084,353, U.S. Pat. No. 5,359,002, U.S. Pat. No. 5,391,399, U.S. Pat. No. 5,614,581, and U.S. Pat. No. 5,132,052.
It now has been found that an in-mold primer coating comprising an epoxy-acrylate copolymer adapted to addition copolymerize with other ethylenically unsaturated components, including particularly minor amounts of a copolymerizable acrylic acid selected from acylic, methacrylic or ethacrylic acids, provides an excellent in-mold primer coating for difficult adhesion substrates, such as thermoplastic polycarbonates and polycarbonate based alloy molding compounds. The in-mold primer coating of this invention further provides excellent interface adhesion with most surface finishes and/or decorative top coatings. The cured in-mold primer coating produces smooth primer surfaces free of surface defects and imperfections, which enables direct finish coat painting without intervening costly refinishing or reworking of the molded part. These and other advantages of this invention will become more apparent by referring to the detailed description of the invention and the illustrative examples herein.
Briefly, the invention pertains to thermosetting in-mold primer coatings for injection and compression molded thermoplastic substrates, especially polycarbonates and polycarbonate plastic alloys, to provide molded thermoplastic parts or articles with a cured in-mold primer coating integrally fused with the surface of the thermoplastic molded substrate. The in-mold primer coating of this invention comprises on a weight percentage basis from about 25% to about 65% or about 74% or about 75% of a low molecular weight epoxy acrylate oligomer having terminal acrylate or methacrylate groups and a number average molecular weight from about 360 to about 2,500, from about 15% to about 40% of an hydroxyl alkyl acrylate or methacrylate, from about 10% to about 35% vinyl substituted aromatic hydrocarbon monomers and from about 1% to about 10% of an acrylic acid.
On a weight parts basis, the in-mold primer coating comprises 100 weight parts of the epoxy-acrylate oligomer, from about 30 to about 70 weight parts of an hydroxyl alkyl acrylate or methacrylate, from about 30 to about 80 weight parts of a vinyl aromatic monomer, and from about 2 to about 20 weight parts of an acrylic acid monomer, where the basis is 100 weight parts of the epoxy-acrylate oligomer. The in-mold primer coating is injected into the mold cavity after the thermoplastic substrate molding composition is at least partially set to form a molded substrate. The injected in-mold primer coating is cured under heat and pressure to become an integrally fused primer surface coating adhered to the molded thermoplastic substrate surface.
The in-mold primer coating composition of this invention is based on a thermosetting copolymerizable composition comprising an epoxy acrylate oligomer, an hydroxy alkyl acrylate, a vinyl aromatic monomer, and an acrylic acid, to provide a curable in-mold primer coating for use on injection and compression molded thermoplastic substrates.
Referring first to the epoxy acrylate oligomer, the epoxy acrylate comprises an epoxy derived intermediate reacted with an acrylic acid such as acrylic acid, methacrylic acid, or ethacrylic acid to produce an acrylate terminated epoxy acrylate having at least two terminal acrylate groups. The epoxy intermediate can be an aromatic epoxy derived from bisphenol-A or a phenolic novalak epoxy, or an epoxy derived from alkylene oxide resins or other diglycidyl functional resin. Bisphenol epoxy intermediates are preferred predominantly comprising the coreaction product of polynuclear dihydroxy phenols or bisphenols with halohydrins to produce epoxy resin intermediates containing at least one, predominantly two, and preferably two terminal epoxy functional groups per epoxy molecule. The most common bisphenols are bisphenol-A, bisphenol-F, bisphenol-S and 4,4xe2x80x2-dihydroxy bisphenol-A. Useful halohydrins include epichlorohydrin, dichlorhydrin, and 1,2-dichlorohydrin-3-hydropropane, with the preferred being epichlorohydrin. A preferred epoxy resin intermediate, for example, comprises the reaction of excess equivalents of epichlorohydrin with lesser equivalents of a bisphenol-A to produce an epoxide group terminated linear chain comprising repeating units of diglycidyl ether of bisphenol-A. Ordinarily excess equivalents of epichlorohydrin are reacted with bisphenol-A where up to two molar equivalents of epichlorohydrin coreact with one molar equivalent of bisphenol-A to produce the diepoxide, although less than complete reaction is possible where some monoepoxide chains may be terminated at the other end with a bisphenol-A unit. Less preferred epoxy resins are predominantly bisphenol-A terminated and esterified with an acrylic acid to produce the epoxy-acrylate oligomer. The most preferred epoxy intermediates are polyglycidyl ethers of bisphenol-A having two terminal 1,2-epoxide groups. Less preferred epoxy intermediate resins comprise epoxide terminated epoxy novalac resins produced similar to bisphenol epichlorohydrin epoxies described above.
The epoxy terminated intermediate, preferably a diepoxide, is further reacted with excess equivalents of an acrylic acid to provide an acrylate terminated epoxy having acrylate double bonds essentially terminating each terminal end of the epoxy intermediate. The preferred epoxy acrylate is an epoxy diacrylate. Acrylic acids comprise acrylic acid (preferred) or a low alkyl, e.g., 1 to about 3 carbon atoms, substituted acrylic acid such as methacrylic acid or ethacrylic acid. Useful molecular weights of epoxy acrylates are number average molecular weights from about 360 to about 2,500, and preferably from about 1,000 to about 2,000, as measured by GPC.
Epoxy acrylates are mixed with copolymerizable hydroxy alkyl acrylates in accordance with this invention. Useful hydroxy alkyl acrylates comprise alkyl acrylates and methacrylates where the alkyl group contains from 1 to about 10, and preferably from 1 to about 5, carbon atoms. Useful alkyl groups include for instance methyl, ethyl, propyl, butyl, and higher alkyl groups where propyl is the preferred alkyl chain and hydroxyl propyl acrylate is the preferred hydroxy acrylate. Hydroxy alkyl acrylates and/or methacrylates comprise from about 30 to about 70 parts by weight, and preferably from about 40 to about 60 parts by weight per 100 parts by weight of the epoxy-acrylic oligomer. One or more hydroxy alkyl acrylates can be utilized in the in-mold coating.
A further copolymerizable component of the thermosetting in-mold primer coating composition of this invention comprises a vinyl substituted aromatic hydrocarbon monomer including for example styrene, lower alky, e.g., 1 to about 5 carbon atoms, substituted styrenes such as alpha methyl and ethyl styrenes, vinyl toluene, halo substituted styrenes such as alpha-chloro styrene, and similar mono-vinyl aromatic monomers. On a weight basis, the copolymerizable in-mold primer coating composition of this invention contains from about 30 to about 80 parts by weight, and preferably from about 40 to 70 parts by weight vinyl aromatic monomer per 100 parts by weight of the epoxy-acrylic oligomer.
In accordance with this invention, a minor amount of an acrylic acid monomer selected from acrylic acid, methacrylic acid, ethacrylic acid, or mixtures thereof, is included in the copolymerizable in-mold primer coating mixture. The inclusion of an acylic acid component has been found to be particularly effective in providing adhesion to particularly difficult adherent thermoplastic substrates such as thermoplastic polycarbonate and polycarbonate based thermoplastic alloys. The preferred acrylic acid is methacrylic acid. On a weight basis, the copolymerizable in-mold primer coating composition comprises from about 2 to about 20 parts by weight, and preferably from about 5 to about 15 parts by weight per 100 parts by weight of the epoxy-acrylic oligomer.
The in-mold primer coating of this invention can contain minor amounts of copolymerizable other mono-ethylenically unsaturated alkyl or alicyclic monomer having a carbon to carbon double bond unsaturation including vinyl monomers, allylic monomers, acrylamide monomers, and similar mono-ethylenically unsaturated alkyl or alicylic monomers. Useful vinyl monomers include vinyl esters such as vinyl acetate, vinyl propionate, vinyl propionate, vinyl butyrates, vinyl isopropyl acetates and similar vinyl alkyl esters, and vinyl alicyclic monomers such as cyclohexane. Useful acrylamide monomers include, for instance, methyl, ethyl, propyl, butyl, 2-ethyl hexyl, cylocohexyl, decyl, isodecyl, benzyl and similar lower alkyl acrylamide or methacrylamide monomers. N-alkoxymethyl derivatives can also be used such as, for example, N-methylol, N-ethanol acrylamides or methacrylamides. On a weight basis, the in-mold coating can contain from 0 to about 20 weight parts of other mono-ethylenically unsaturated alkyl or acylic copolymerizable monomer based on 100 weight parts of copolymerizable epoxy acrylate oligomer in the in-mold primer coating composition.
The in-mold primer coating composition can contain, if desired, a minor amount of an additional low molecular weight diacrylate such as acrylic or methacrylic diester of a diol. The in-mold primer coating can contain, if any, from about 0.1 or about 1 to about 10 weight parts of such other low molecular weight diacrylate, if desired.
On a weight parts basis, the in-mold primer coating of this invention comprises 100 weight parts of epoxy-acrylate oligomer, from about 30 to about 70 weight parts and preferably from about 40 to about 60 weight parts, of an hydroxyl functional acrylate or methacrylate, from about 30 to about 80 weight parts, and preferably from about 40 to about 70 weight parts, of a vinyl aromatic monomer, from about 2 to about 20, and preferably from about 5 to 15 weight parts, of an acrylic acid selected from acrylic, methacrylic, and/or ethacrylic acid, with the balance if any being minor amounts of 1 to about 20 weight parts of other mono-ethylenically unsaturated monomer(s) and/or low molecular weight other diacrylate, where weight parts are based on 100 weight parts of the epoxy-acrylic oligomer.
The in-mold primer coating of this invention comprising epoxy acrylate, hydroxyl alkyl acrylate, vinyl aromatic monomer, and an acrylic acid component is copolymerized and thermoset under heat in the presence of a free radical initiator such as peroxide. Useful peroxides include t-butyl peroxide, t-butyl perbenzoate, t-butyl peroctate, dibenzoyl peroxide, methyl ethyl ketone peroxide, diacetyl peroxide, t-butyl hydroperoxide, ditertiary butyl peroxide, benzoyl peroxide, t-butyl peroxypivalate, 2,4-dichlorobenzoyl peroxide, decanoylperoxide, propionyl peroxide, hydroxyheptyl peroxide, cyclohexanone peroxide, dicumyl peroxide, cume hydroperoxide, and similar free radical peroxide initiators. Azo free radical initiators can be useful including for instance azo bis-isobutyronitrile, dimethyl azobis-isobutyrate, and similar azo free radical initiators. A preferred initiator is t-butyl perbenzoate. Free radical peroxide or azo initiators are added to the copolymerizable in-mold primer coating at a level above about 0.5%, desirably from about 1 to about 5%, and preferably from about 1% to about 2%, by weight based on the weight of the copolymerizable thermosetting components of the in-mold primer coating composition comprising epoxy acrylate oligomer, hydroxy alkyl acrylate, aromatic monomer, acrylic acid monomer and other polymerizable components if any.
In conjunction with the free radical initiator, an accelerator can be added, if desired to accelerate curing, including cobalt driers such as cobalt napthenate or octoate, or other metal napthenates such as zinc, lead, and manganese napthenates, or mixtures of such accelerators. Ordinarily minimal amounts of accelerator are used, if desired, at levels from about 0.01% to about 1%, preferably from about 0.01% to about 0.5%, based on the weight of the copolymerizable thermosetting components in the in-mold primer coating composition. Conversely, inhibiters can be added to control and delay cure times, if desired, such as benzoquinone, hydroquinone, and methoxyhydroquinone. Inhibiters if used are added at very low levels, typically below 0.1% to delay and properly control the copolymerization rate of the in-mold primer coating.
The in-mold copolymerizable thermosetting primer coating composition can be compounded with other additives, known to the art and to the literature, such as opacifying pigments, tinting pigments or colorants, and inert fillers. Useful opacifying pigments include titanium dioxide, zinc oxide, titanium calcium, while tinting pigments include a variety of oxides, chromium, cadmium, and other tinters. Carbon black ordinarily will be used predominantly in the in-mold primer coating of this invention to provide a black or gray primer coating appearance. Useful fillers include clays, silicas, talc, mica, wood flower, barium sulfate, calcium and magnesium silicates, aluminum hydroxide, barium sulfate, and magnesium and calcium carbonates, where preferred fillers are talc and barium sulfate. Opacifying pigments, tinting pigments or colorants, and inert fillers can be used at a level from about 0 to about 80 weight parts per 100 weight parts of copolymerizable in-mold coating composition.
Other additives to the in-mold primer coating can include lubricants and mold release agents such as zinc or calcium stearate, phosphoric acid esters, and zinc salts of fatty acids. Mold release agents can also be used to control the cure rate, where zinc fatty acids tend to moderately accelerate the cure time, while calcium fatty acids tend to moderately retard the cure time. A low profile additive, such as polyvinyl acetate, can be added if desired to avoid molding shrinkage of the in-mold primer coating.
The thermosetting in-mold primer coating composition of this invention can be prepared by mixing together the epoxy acrylate, hydroxy alkyl acrylate, vinyl aromatic monomer, and acrylic acid component to form a uniform fluid resinous blend. The free radical initiator can be added to the resinous mixture, or added with one on the resinous components such as the aromatic monomer, along with accelerator if any, and inhibiter if any. Other compounding ingredients of pigments, colorants and fillers and other additives can be added as desired and mixed to form a uniformly dispersed in-mold primer coating composition.
Referring now to particularly useful thermoplastic substrates, the thermosetting in-mold primer coating compositions of this invention are particularly suitable for obtaining good adhesion over a thermoplastic polycarbonate based substrate, such as polycarbonate and polycarbonate plastic alloys. Thermoplastic polycarbonates are primarily aromatic polyesters derived from reaction of carbonic acid derivatives with primarily an aromatic diol. For example, polycarbonates can be formed by phosgene reaction with a diol such as bisphenol-A, or by a melt transesterification between bisphenol-A and a carbonate ester such as diphenyl carbonate. Poly(bisphenol-A carbonate) is a condensation polymer ordinarily synthesized from bisphenol-A and phosgene in the presence of monophenol chain terminator to control molecular weight. The most common polycarbonate is bisphenol-A based produced by interfacial reaction of bisphenol-A with carbonyl chloride where molecular weight can be controlled by a phenolic chain stopper. Useful number average molecular weights of aromatic thermoplastic polycarbonates ordinarily are from about 10,000 to about 50,000, where from about 22,000 to about 35,000 molecular weights are preferred.
Polycarbonate polymeric blends or alloys with other thermoplastic polymers are likewise useful thermoplastic substrates on which the thermosetting in-mold primer coating of this invention achieves good substrate adhesion. Useful polycarbonate alloy blends include aromatic polycarbonate mixed with poly(butylenes terephthalate) known as PC/PBT, and aromatic polycarbonate blended with poly(ethylene terephthalate) known as PC/PET, as well as other polymeric alloy blends with aromatic polycarbonate. Such polycarbonate alloys ordinarily comprise a mixture of polycarbonate containing from about 40 to about 95 weight percent aromatic polycarbonate with the balance being the alloying secondary thermoplastic polymer or polymers. Additives to polycarbonates and alloy blends thereof can include tinting pigments, colorants, heat stabilizers, impact modifiers, lubricants, mold release agents, UV stabilizers, plasticizers, fibers, reinforcing materials, fillers, and other additives ordinarily added to injection molding thermoplastic substrate compounding resins as desired.
The thermosetting in-mold primer coating of this invention is particularly useful as an in-mold coating for molding of polycarbonate alloys comprising major amounts of polycarbonate mixed with minor amounts of Nylon, ABS, PET, PBT, and/or HIPS. The Polycarbonate and alloying co-polymer can be heated to make the two polymeric material miscible or partially miscible depending on the alloying polymer. The polymers may or may not interact, such as by ester interchange, during the heat alloying process. The polycarbonate ordinarily is the dominant matrix polymer but need not be. On a weight basis, polycarbonate alloys comprise by weight from about 40 to about 95% polycarbonate, preferably from about 50 to about 80% polycarbonate, with the balance being blend or alloying polymer or polymers.
Nylons are polyamides having repeating amide groups ordinarily produced by condensation polymerization of a dibasic acid with a diamine or addition polymerization of a ring monomer compound having both carboxylic acid and amine groups on the same monomer. For example, adipic acid or similar 6 to 12 carbon dibasic acid, or longer aliphatic chain, can be condensation polymerized with hexamethylene diamine adipamide, while e-caprolactam can be homopolymeized to form polycaproamide. Nylon can be alloyed with polycarbonate and compounded with fillers and additives in much the same manner as polycarbonates.
ABS is a polymeric material comprising copolymerization of acylonitrile, butadiene, and styrene in various ratios to form a terpolymer comprising butadiene rubber grafted with styrene-acrylonitrile and provide a thermoplastic exhibiting various physical and strength properties, as desired. Acylonitrile contributes stability, chemical resistance, and aging resistance, while butadiene provides low temperature property retention, toughness, and impact strength, and styrene provides rigidity. Ordinarily ABS comprises from about 5 to about 30% by weight butadiene rubber with the balance being styrene-acrylonitrile copolymer. A fourth monomer can be copolymerized if desired to provide special properties, such as alpha-methyl styrene for high heat deflection. ABS can be alloyed with polycarbonate to form a polycarbonate alloy which can be compounded with pigments, filler and other additives in much the same manner as polycarbonates to form a thermoplastic molding composition for injection molding of thermoplastic substrates. The thermosetting in-mold primer coating of this invention can be applied to the molded ABS modified polycarbonate substrate by in-mold injection of the primer coating in accordance with this invention.
Polyethylene terephthalate is known as PET. PET is a polycondensation polymerized polymer of ethylene glycol and terephthalic acid, or ethylene glycol transesterified with dimethyl terephthalate, to produce PET. Ordinarily ethylene glycol is esterified or transesterified using a continuous melt phase condensation polymerization process, or transesterification process, and can be followed by solid-state polymerization at higher temperatures to obtain higher molecular weight PET, if desired. PET can be alloyed with polycarbonate and compounded with other compounding ingredients to provide a thermoplastic injection molding compound useful as an injection molded substrate capable of achieving good surface adhesion with the in-mold primer coating in accordance with this invention.
Polybutylene terephthalate is commonly known as PBT. Polybutylene terephthalate or polytetramethylene terephthalate is made by direct esterification of 1,4-butanediol with dimethyl terephthalate in much the same manner as PET. The PBT thermoplastic can be alloyed with polycarbonate and compounded with filler, pigments, and other additives similar to polycarbonate compounding.
High impact styrene is commonly known as HIPS. High impact styrene is polystyrene reinforced with a rubber compound comprising a non-crystalline polystyrene thermoplastic toughened by incorporating a rubber additive without diminishing other properties. The rubber additive component comprises a large number of small gel particles with a modulus much lower than the matrix polystyrene. The rubber gel particles are added to avoid brittle fracture by absorbing impact energy through micro-craze formation at the gel particles, while preventing craze propagation cracks, to provide a thermoplastic substrate that does not bend or crack under stress due to high flexural modulus. The rubber gel particles ordinarily comprise polybutadiene and typically are about 1 to 2 millimicrons in size. HIPS thermoplastic resins can be alloyed with polycarbonate and compounded with other additives and compounding components in much the same manner as polycarbonates to provide an injection molded substrate. The alloy of polycarbonate with HIPS provides an injection molded substrate having good adhesion with the in-mold primer coating of this invention.
The in-mold primer coating of this invention is similarly useful on other thermoplastic substrates in addition to polycarbonate and polycarbonate alloyed thermoplastic. Useful other thermoplastic substrates include PET, PBT and copolymers, nylon, ABS, HIPS, and thermoplastic polyurethanes.
Injection molding involves heating the resinous compounding composition to a temperature above the melting point of the compounding resin and injecting the heated resin melt into an injection mold cavity for molding a substrate part or article. The substrate resinous molding compound ordinarily is injected into the cavity of an injection mold and molded under heat and pressure to at least partially set the thermoplastic molding resin and form a molded substrate. Substrate molding temperatures typically are from about 100 to about 300xc2x0 F. and preferably from about 150 to about 250xc2x0 F. During the molding and cooling stage, the injection molding pressure preferably is partially released from the mold to permit injection of the in-mold appearance coating of this invention into the minimally opened mold under reduced low pressure. Alternatively, the substrate molding compound can be injection molded under high pressure followed by injecting the in-mold coating at a higher pressure into the mold maintained closed under pressure A metered amount of the in-mold coating containing initiator, additives, and other compounding ingredients as desired is injected into a nozzle located within the parting line of the mold cavity and preferably disposed opposite from the thermoplastic substrate injection sprues. Pressure can be applied as needed and ordinarily can be from about 2,000 to about 5,000 psi, and preferably from about 3,000 to about 4,000 psi, but ordinarily at a pressure considerably less than the pressure applied while molding the substrate resinous compound. The applied pressure can increase as the in-mold appearance coating is injected between the partially molded substrate and the mold cavity surfaces. The in-mold coating is heat cured to conduct copolymerize the epoxy acrylate oligomer, hydroxy alkyl acrylate, the vinyl aromatic monomer, and the acrylic acid monomer to form a fully cured in-mold primer surface coating advantageously molded integrally with and fusion adhered to the fully formed thermoplastic substrate. In-mold coating curing temperatures can be from about 150 to about 300xc2x0 F. for time sufficient to fully cure the in-mold coating. The heat curing intervals typically are from about 30 to about 120 seconds and preferably from about 60 to about 90 seconds. The mold is then opened and the surface coated molded part or article can be removed from the mold cavity. The cured surface coating provides excellent adhesion to the polycarbonate based substrate as well as an excellent primer surface amenable to good adhesion with a wide variety of top surface finish coatings.

In-mold primer coating for thermoplastic substrates


An acoustic guitar is combined with a cassette tape player carried inside of the body of the guitar and arranged for playing recorded music simultaneously with live music being played on the guitar by a musician. Necessary switches, wiring, and power supplies are also included. In one version of the assembly all components are carried inside or on the surface of the guitar so as to provide a self-contained assembly. Another version includes an external, large amplifier/speaker located away from the guitar but interconnected with controls and a pickup device on the guitar.

This invention relates to musical instruments and more particularly to hollow string instruments equipped with devices for playing previously recorded music.
Various applications exist for musical instruments combined and integrated with devices such as cassette tape players which can play previously recorded music. For training purposes, a student playing the musical instrument could learn timing as well as other aspects of performing a musical piece by following the lead of a cassette recording being played simultaneously. The cassette recording also might provide background music or accompaniment for a performer. A musician/song writer could record his or her music for a new song on a tape cassette and play and/or sing along with the recording.
Systems which enable playing of live music on an instrument simultaneously with reproducing sounds of recorded music at the same instrument lend themselves to use by a performer who wishes to create an initial impression that the sounds being heard are coming only from the live music source. This requires that necessary components for operation of the recorded music player device be placed inside of the instrument where possible as may be done to a large extent for hollow string instruments such as acoustic guitars. The cassette components should be placed so as not to unduly interfere with playing the guitar or to adversely affect the quality of live music sounds. Furthermore, controls for operation of the device should be readily accessible on the body of the guitar so that switching operation will not be noticeable or distracting to any audience. Another desirable feature for a self-contained acoustic guitar/cassette tape playing system would be compatibility with certain external components such as an external amplifier/speaker located away from the guitar. In such case, controls for the external component should be carried on an outer surface of the guitar at an easily accessible location. Use of an external amplifier/speaker would enable greater volume as may be required outdoors or in auditoriums and large rooms.
The present invention is directed to a musical assembly comprising a hollow string instrument, in particular an acoustic guitar, combined with a device such as a cassette tape player carried inside the body of the instrument, with the cassette tape player being adapted for playing pre-recorded music simultaneous with live music being produced on the instrument by a performer. The cassette tape player may be supported inside the guitar body by a receptacle provided at an edge rim of the guitar body and positioned such that the cassette extends below the surface of the rim. Other components of the assembly, as would be required for a complete operating system, include speakers located inside the body and having their forward ends secured around apertures provided in a front panel of the body, a power supply, an electrical switch, connecting wires and supporting structure for securing all components to the body of the instrument. Components added to and combined with the guitar may be located within or at the surface of the guitar so as to avoid use of external, remote components in a self-contained embodiment.
While the assembly of this invention may be provided in an entirely self-contained form, that is, without any connections to external power sources, additional speakers or the like, it is compatible with such further enhancements when desired in certain situations. In particular a capability for higher volume may be needed for performing outdoors or in auditoriums and large rooms. External components such as large amplifiers/speakers powered by a remote 110V AC power system may be connected to control switches on the guitar and wired to receive signals from the cassette player or from a pickup device installed on the guitar. This measure enables a greater volume of sound from the live music source to be produced in comparision to the volume of sound from the recorded source. Flexibility in blending sounds from each source with one another is also enabled.
It is accordingly an object of this invention to provide a musical entertainment assembly including a hollow string instrument and a device for playing recorded music located inside the body of the instrument.
Another object is to provide a combined assembly of an acoustic guitar and a means for playing recorded music simultaneously with playing of the guitar.
Yet another object is to provide a means for operably connecting a remote speaker/amplifier to an acoustic guitar whereby the speaker/amplifier may be integrated with operation of a cassette player carried by the guitar.
Other objects and advantages of the invention will be apparent from the following detailed description and the appended claims.

Acoustic guitar with internally located cassette tape player


Data transfer rates on a network are controlled in conjunction with TCP/IP protocols by limiting the available space in a receive buffer located on the receiver. Limits are generated by either moderating the rate that data is removed from the receive buffer or changing the receive buffer's size. Transfer rates are reduced to decrease the impact large transfers have on other network traffic and to reduce the total number of lost data packets. Reduced rates and priorities can be managed by scheduling systems.

1. Field of the Invention
The invention relates to network communications and more specifically to the management of data transfer rates under TCP/IP protocols.
2. Background of the Invention
As illustrated in prior art FIG. 1, a computer network, generally designated 100, includes a plurality of receivers 110, each connected through communications channels 115 to a network 120. Network 120 is also connected through communications channels 115 to a sender 130 and an intermediary 140. Intermediary 140 serves as a transmission node or cache system between various parts of network 120, sender 130, or receivers 110. In some cases, receiver 110 and sender 130 are a network client and network server respectively.
Communications between the elements of computer network 100 are typically managed using a layered series of software and hardware systems. Prior art FIG. 2 illustrates some of the various layers involved when computer network 100 includes the World Wide Web. A top layer includes FTP/HTTP 210 (File Transfer Protocol and Hypertext Transfer Protocol). These standard components serve as the interface between lower levels of the communication system and application programs such as browsers. FTP/HTTP 210 operates above a TCP (Transmission Control Protocol) 220 layer that facilitates the delivery and reception of data packets to and from devices in computer network 100. IP (Internet Protocol) 230 layer, data link 240 layer, and physical network 250 perform well known standard operations enabling the transfer of data.
TCP 220 includes software running on both sender and receiver 110 devices. TCP 220 hides the details pertaining to the network and its characteristics from FTP/HTTP 210 and communicates with FTP/HTTP 210 through a simple TCP application programming interface (API). TCP 220 has three roles: (a) it prevents congestion at the receiver, (b) it prevents congestion in the network along the path used from source to destination, and (c) it guarantees a reliable data transfer.
At sender 130, buffers in TCP 220 receive data to be transferred from applications at FTP/HTTP 210. These buffers are referred to as the "TCP Send Buffers." Likewise, at receiver 110, there are "TCP Receive Buffers" associated with each sender 130, from which applications on receiver 110 read data transferred over network 120. A pair of send and receive buffers exists for each TCP connection. Data are written to and read from the send and receive buffers in blocks of various sizes.
FIG. 3 illustrates a prior art receive buffer 310 associated with TCP 220 on a receiver 110. Receive buffer 310 contains data 320 and has a limited available space of a size, known as the receive window Wr 330, where additional data could be stored. TCP 220 uses an explicit feedback mechanism to prevent congestion at receiver 110 and overflow of receive buffer 310. Receiver 110 declares the size (number of bytes) of receive window Wr 330 in each acknowledgement sent back to sender 130. Sender 130 never allows the amount of outstanding data transmitted and not yet acknowledged to exceed Wr 330.
To prevent congestion along a communications path, TCP 220 follows a congestion control algorithm that limits the amount of outstanding data. The congestion control algorithm contends with the fact that no information is available regarding the available bandwidth of the path from sender 130 to receiver 110. The congestion control algorithm starts by allowing a small amount of outstanding data and then increases the amount of outstanding data allowed as acknowledgements are received from receiver 110. The amount of outstanding data allowed by the congestion control algorithm is referred to as the congestion window (Wc). The actual amount of data that can be sent is the send window (Ws), which is equal to the minimum of Wr 330 and Wc.
To illustrate the dynamics of the congestion window Wc, one may momentarily assume that there is an abundance of data to send and that receive window Wr 330 is very large, and therefore does not place any limitation on the size of the send window Ws. The congestion control algorithm starts with a small congestion window (Wc) equal to the maximum size of a single TCP segment. The first transmission includes only one TCP segment, carrying at most an amount of data equal to the maximum segment size (MSS). When an acknowledgement of the first segment is returned from receiver 110, the congestion window Wc is increased by another MSS to two times MSS. Since, for this illustration, Wr 330 is assumed to be very large, the send window Ws also becomes two times MSS. The maximum amount of data that can be sent in the next transmission (Ws) is now two times MSS. When two segments are sent, each is acknowledged independently by receiver 110 and as each acknowledgement is received the congestion window Wc is increased by MSS. After both acknowledgements are received from a two-segment transmission, Wc (and Ws) will equal four times MSS. By increasing the size of the congestion window by one MSS for each acknowledgement received, the number of segments in each transmission doubles as each previous transmission is fully acknowledged. This increase continues until the congestion window Wc reaches a certain value called the "threshold." Beyond the threshold, the congestion window Wc is incremented by only one MSS for each set of transmissions. This phase of the congestion control algorithm is referred to as the congestion avoidance phase. The congestion window Wc keeps increasing, albeit at a smaller (linear) rate instead of an exponential rate, until the size of the congestion window Wc reaches a preset maximum. This maximum is a predetermined system parameter. Since the congestion window Wc increases over time, the likelihood of congestion and, therefore, loss of a packet on the network also increases over time. If a TCP segment is lost in the network, the lack of acknowledgement from receiver 110 within a timeout period triggers the retransmission of the lost segment and all segments following it and also resets the size of congestion window Wc (and Ws) to MSS. The process described above is then repeated. TCP 220, therefore, does not maintain a constant transmission rate, but rather transmits data using a congestion window that increases according to first an exponential rule and then a linear rule until a transmission loss occurs and Wc is reset.
FIG. 4 is a prior art illustration of congestion window Wc size as a function of time. During an initial phase 410 the congestion window Wc increases exponentially, from an initial size of one MSS, until it reaches a threshold (Thr 430). Wc then increases linearly during a second phase 440, until at time 450 a segment (data packet) is lost at which time Wc is reset to one MSS and the process is repeated. Time 450 can occur at any point in each cycle. Wc will stop increasing if a maximum size (max 480) is reached before a data segment is lost. The loss of data segments is dependent on the bandwidth of network 120 and the constantly variable traffic it supports. The value of max 480 is a system parameter associated with elements on network 120. After a packet is lost, a new threshold (ThrB 420) is set as a function of the largest window size reached on the previous cycle. The cycles are repeated until all data transmission is completed or a timeout occurs.
When Wr 330 is finite the send window, Ws, is determined by Wr 330 if Wr 330 is less than Wc. Ws is always the minimum of the current value of Wc and the most recently declared value of Wr 330.
A method of controlling the rate of data transfer is to limit the rate at which the application at sender 130 writes data to the send buffer. This is accomplished by limiting the size and frequency of data blocks written to the send buffer. Writing blocks of small size and high frequency can represent a high overhead at sender 130. Since sender 130 is typically a server serving a large number of clients, the preference of sender 130 is to use large blocks, and to control the rate by controlling the frequency of writes. However, writing large size blocks gives TCP 220 an opportunity to send large batches. Large batches generate traffic of a bursting nature and thus are more likely than traffic of a steady nature to cause congestion in network 120.
The prior art systems described above have a number of disadvantages. The variable send window Ws implies that an optimal transmission rate is never maintained. The average transmission rate also varies as a function of total traffic on the network. This variability makes scheduling of large data transfers difficult and allows large transfers to have a significant impact on other data. To be practical any solutions to these problems must be made utilizing the current standardized protocols.
Two prior art methods of regulating transfer rates involve intercepting the acknowledgement sent from receiver 110 to sender 130. In the first method the acknowledgement is delayed for a period of time and in the second the value of Wr reported within the acknowledgement is modified by inserting a new value. Both of these approaches have significant disadvantages, including the necessity of intercepting packets in the network.
Further information about TCP/IP and the state of the art in data transfer methods is found in the following references:
W. Richard Stevens, "TCP/IP Illustrated. Vol I—The Protocols," Addison-Wesley, 1994;
Comer, Douglas, "Internetworking with TCP/IP. Vol. I.," Prentice Hall, 1991;
Comer, Douglas, and Stevens, David, "Internetworking with TCP/IP. Vol. II.," Design, Implementation, and Internals. Prentice Hall, 1991; and
Packer, Robert L., "Method for Explicit Data Rate Control in a Packet Communication Environment Without Data Rate Supervision", U.S. Pat. No. 6,038,216.

System and method for controlling data transfer rates on a network


An arrangement in a circulation lubrication system includes a lubricating oil tank, pressure pipe lines for supplying oil to parts that are to be lubricated, return pipe lines for returning the oil from the parts that are to be lubricated to the oil tank, and a mechanism for pumping oil into the pressure pipe lines and maintaining a desired state of lubrication. The lubricating oil tank has a rotationally symmetric structure; and a return duct, positioned at the center axis of the rotationally symmetric structure, is configured to extend below the surface of the oil in the lubricating oil tank. A return flow through the return duct passes through a dividing element to a mechanism configured to separate impurities from the oil.

1. Field of the Invention
The invention relates to an arrangement in a circulation lubrication system comprising a lubricating oil tank; pressure pipe lines for supplying oil to parts to be lubricated; return pipe lines for returning the oil from the parts to be lubricated to the oil tank; and means for pumping oil into the pressure pipe lines and maintaining a desired state of lubrication.
2. Description of the Related Art
Circulation lubrication systems are today used widely to lubricate various machines especially when the lubricant is used for cooling the parts to be lubricated. An example of the use of circulation lubrication is the lubrication of the bearings of the drying cylinders in paper machines or the lubrication of gas turbines. In both cases the bearings are subject to a thermal load from the outside.
Circulation lubrication is also used when the part to be lubricated creates considerable dissipation power. One example of such applications is the lubrication of gear boxes.
Still another use of circulation lubrication is in cases where the lubricant may get dirty in the part to be lubricated, and it should be possible to reuse the lubricant after cleaning.
A circulation lubrication system usually comprises a pump operated by an electric motor. The pump brings the oil into motion. The output of the pump is usually selected so that it exceeds the required flow rate by 10 to 20%, so that a sufficient operating margin is left for the control of bypass pressure. Oil is arranged to pass through replaceable filters. The filters are often arranged in two groups so that one group can be separated by means of valves and the filters can be changed without having to stop the entire assembly. An electric or steam-operated heater is often used for further heating the oil. The oil is cooled by a heat exchanger having water or air cooling means. The cooling power is adjusted by a temperature regulator provided for supply oil. The set value of the temperature regulator is often typically about 55xc2x0 C. Pressure control is often effected by a bypass valve back to the oil tank. Depending on the system, the set values of the pressure controller typically vary between 5 and 20 bar.
Oil is supplied to parts needing lubrication, such as different parts in paper machine, by means of pressure trunk pipes usually made of rustproof material. The oil flows in the pipes as a laminar flow, and so the pressure drop is small. From the trunk pipes the oil is distributed to a plurality of flow metering boards wherefrom it is divided into rising pipes to be supplied to a number of parts to be lubricated. From these parts the oil is passed through return pipes by utilizing gravitation into collector pipes on the return side. The oil is passed under the influence of gravitation through the collector pipes into the tank of the circulation lubrication assembly. The pipes on the return side are never full of oil. The inclination of the pipes is about 2 to 3% towards the tank of the assembly. Before the tank the return oil is passed through a coarse-mesh filter. The oil returned into the tank is then again sucked into circulation by the pump. The dimensions of the tank are usually such that the oil stays in the tank for a certain period of time depending on the viscosity of the oil.
In the system the lubricating oil tank has several functions for conditioning the oil before recirculation. One function of the tank is to allow air bubbles contained in the oil to rise to the surface. Air bubbles may increase the liability of the pump to cavitation, and they may deteriorate the lubricating film formed on the part needing lubrication. Another function is to allow large dirt particles with density considerably higher than that of oil to deposit on the bottom of the tank. To some extent water drops contained in the oil will also fall down in the tank. The density of water is so close to that of oil that the falling speed is slow. The tank condenses moist air flowing in the return pipes on the tank walls and drains the water along the walls, thus collecting it on the bottom of the tank. The tank also cools the oil through the walls. Furthermore, the tank forms a space into which the pipe lines are emptied at system shutdowns, and the tank serves as an oil storage in case of a pipe leakage, so that the machine to be lubricated can be shut down controllably. Still another function of the pump is to make sure that there is always oil in the pump suction means in order that air would not be sucked along. The moisture and suitable temperature also enable bacteria to grow in the tank.
The tank also comprises thermostat-controlled oil heaters, which may be either electric or steam-operated heaters. The heaters are used to heat the great amount of oil contained in the oil tank within 4 to 8 hours typically to about 55xc2x0 C. before the system is started as the screw pumps used are not able to pump cold oil of high viscosity at full power without the risk of cavitation.
Present circulation lubrication oil tanks have had similar basic solutions for decades. A tank is basically a rectangle, the capacity of which may typically vary from a few hundred liters up to 30 cubic meters. The size required depends on the operating principle of the tanks, according to which principle, to keep in good condition, the oil must be allowed to rest in the tank about 30 minutes, so that impurities contained in the oil could be separated before the oil is recirculated. In addition to storing the oil, the tank must also cool the oil and be able to separate air, water and other impurities from the oil as stated above.
Because of their big size, the previously used tanks are often difficult to place in connection with machinery needing lubrication. Furthermore, a great amount of oil involves great investments, and especially today, it also involves a fire load, brought about by a great capacity, with other environmental risks. In practice, measurements have also proved that despite the big size of the tank only a small portion of the capacity of the tank is efficiently involved in the oil circulation. When the function of the flow fields is measured by calculating courses of particles without a mass, the same phenomenon is observed also numerically. In a typical conventional tank provided with partition walls the operating efficiency is only 35 to 44%, which indicates the actual flow-through time in proportion to the theoretical flow-through time. In practice, for example a tank of 8 cubic meters, in which 350 liters of oil flow per minute, has the theoretical flow-through time of 22 minutes 52 seconds, in which time the amount of oil would go once through the system. In reality however, warm oil entering the tank tends to form internal flow channels inside the tank due to differences in the viscosity of oil. These channels make the contents of the tank form walls in a stationary oil mass and a main flow-through channel formed in the oil mass. In reality, the theoretical flow-through time of 22 minutes 52 seconds is now in a range of 8 to 10 minutes, which is definitely too short. In addition to channeling, the flow field of previously known tanks is also subject to heavy whirl forming, which makes the separation of dirt particles difficult. Channeling results from high flow rates in the tank.
The object of the invention is to provide an arrangement, by means of which the drawbacks of the prior art can be eliminated, i.e. to provide a flow field that is as even as possible, which would result in a substantially more efficient use of oil capacity and a more efficient separation of dirt particles as compared with previous solutions. This is achieved by means of an arrangement according to the invention, which is characterized in that the lubricating oil tank has a rotationally symmetric structure, and that the return duct is arranged at the centre axis of the rotationally symmetric structure and further arranged to reach below the surface of the oil contained in the lubricating oil tank, and that the flow through the return duct is arranged to be passed through a dividing element to means for separating impurities.
The primary advantage of the invention is that it allows a very efficient use of the oil capacity and very efficient separation of impurities. Another advantage of the invention is that it is simple so that its introduction and use are economical.

Arrangement in a circulation lubrication system


A residential water supply interruption system generally comprises a remotely controllable shut-off valve and a controller in communication with the remotely controllable shutoff valve. The remotely controllable shutoff valve is interposed a water line from a water main to the living quarters portion of a residential building, such that activation of the shutoff valve operates to prevent flow of water from the water main to the living quarters. In this manner, damage to the living quarters from failure of water pipes running through the living quarters is prevented during times that the shutoff valve is activated.

The present invention relates to plumbing systems. More particularly, the invention relates to a system whereby water related residential damages may be reduced or eliminated by selectively disrupting flow of water into the residence.
Losses to residential property owners incident damages caused by broken water pipes are staggering. In part because broken water pipes often go undetected in the absence of the property owner or while the property owner sleeps through the night, water damage from a broken water pipe can be catastrophic. In fact, some insurance agencies report that up to seventy percent of their insurance losses are water related.
It is therefore an overriding object of the present invention to improve upon the prior art by providing a system whereby residential property owners may easily protect themselves against catastrophic damages caused by broken water pipes. Additionally, it is an object of the present invention to provide such a system that may be operated manually or automatically. Finally, it is an object of the present invention to provide such a system that is economical to implement and reliable in operation.
In accordance with the foregoing objects, the present inventionxe2x80x94a residential water supply interruption systemxe2x80x94generally comprises a remotely controllable shut-off valve and a controller in communication with the remotely controllable shutoff valve. The remotely controllable shutoff valve is interposed a water line from a water main to the living quarters portion of a residential building, such that activation of the shutoff valve operates to prevent flow of water from the water main to the living quarters. In this manner, damage to the living quarters from failure of water pipes running through the living quarters is prevented during times that the shutoff valve is activated.
To easily activate the remotely controllable shutoff valve, the controller preferably comprises an electric switch, which may be conveniently located within the living quarters at, for example, an entrance doorway. The switch, in turn, is in communication with actuator, such as a motor or solenoid mechanism, operably collocated with the shutoff valve. In this manner, occupants may simply flip the switch on the way out of the residential building, thereby causing the flow of water into the living quarters to be blocked. In an extension of the present invention, the controller may also be provided with a timer for automatically operating the switch according to a user-defined schedule. In this embodiment, the timer may automatically cause disruption of water flow into the residential quarters at times that occupants are normally expected to be absent or normally expected to not require water such as, for example, during the nighttime hours. In the latter case, it is preferable that the controller be provided with an override, which may be remotely operable through a radio link, to allow temporary water flow as required for the single flushing of a toilet or the like.
Although those of ordinary skill in the art will recognize many substantial equivalents, the remotely controllable shutoff valve may comprise a ball valve operable via and electric motor or a gate valve operable via a solenoid mechanism. In either case, it is preferable that the valve actuator be operable at the same voltage levels as commonly utilized in automated sprinkler system controllers. In this manner, the shutoff valve may be easily located in the garage area of the residential building adjacent to the junction to the sprinkler system. As will be apparent to those of ordinary skill in the art, especially in light of this exemplary description, this arrangement allows the shutoff valve to be utilized to protect the residential quarters without interference with the operation of an automatic sprinkler system.
Finally, many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.

Residential water damage prevention system


An improved method for extracting and handling multiple samples for S/TEM analysis is disclosed. Preferred embodiments of the present invention make use of a micromanipulator that attaches multiple samples at one time in a stacked formation and a method of placing each of the samples onto a TEM grid. By using a method that allows for the processing of multiple samples, the throughput of sample prep in increased significantly.

Semiconductor manufacturing, such as the fabrication of integrated circuits, typically entails the use of photolithography. A semiconductor substrate on which circuits are being formed, usually a silicon wafer, is coated with a material, such as a photoresist, that changes solubility when exposed to radiation. A lithography tool, such as a mask or reticle, positioned between the radiation source and the semiconductor substrate casts a shadow to control which areas of the substrate are exposed to the radiation. After the exposure, the photoresist is removed from either the exposed or the unexposed areas, leaving a patterned layer of photoresist on the wafer that protects parts of the wafer during a subsequent etching or diffusion process.
The photolithography process allows multiple integrated circuit devices or electromechanical devices, often referred to as "chips," to be formed on each wafer. The wafer is then cut up into individual dies, each including a single integrated circuit device or an electromechanical device. Ultimately, these dies are subjected to additional operations and packaged into individual integrated circuit chips or electromechanical devices.
During the manufacturing process, variations in exposure and focus require that the patterns developed by lithographic processes be continually monitored or measured to determine if the dimensions of the patterns are within acceptable ranges. The importance of such monitoring, often referred to as process control, increases considerably as pattern sizes become smaller, especially as minimum feature sizes approach the limits of resolution available by the lithographic process. In order to achieve ever-higher device density, smaller and smaller feature sizes are required. This may include the width and spacing of interconnecting lines, spacing and diameter of contact holes, and the surface geometry such as corners and edges of various features. Features on the wafer are three-dimensional structures and a complete characterization must describe not just a surface dimension, such as the top width of a line or trench, but a complete three-dimensional profile of the feature. Process engineers must be able to accurately measure the critical dimensions (CD) of such surface features to fine tune the fabrication process and assure a desired device geometry is obtained.
Typically, CD measurements are made using instruments such as a scanning electron microscope (SEM). In a scanning electron microscope (SEM), a primary electron beam is focused to a fine spot that scans the surface to be observed. Secondary electrons are emitted from the surface as it is impacted by the primary beam. The secondary electrons are detected, and an image is formed, with the brightness at each point of the image being determined by the number of secondary electrons detected when the beam impacts a corresponding spot on the surface. As features continue to get smaller and smaller, however, there comes a point where the features to be measured are too small for the resolution provided by an ordinary SEM.
Transmission electron microscopes (TEMs) allow observers to see extremely small features, on the order of nanometers. In contrast SEMs, which only image the surface of a material, TEM also allows analysis of the internal structure of a sample. In a TEM, a broad beam impacts the sample and electrons that are transmitted through the sample are focused to form an image of the sample. The sample must be sufficiently thin to allow many of the electrons in the primary beam to travel though the sample and exit on the opposite site. Samples, also referred to as lamellae, are typically less than 100 nm thick.
In a scanning transmission electron microscope (STEM), a primary electron beam is focused to a fine spot, and the spot is scanned across the sample surface. Electrons that are transmitted through the work piece are collected by an electron detector on the far side of the sample, and the intensity of each point on the image corresponds to the number of electrons collected as the primary beam impacts a corresponding point on the surface.
Because a sample must be very thin for viewing with transmission electron microscopy (whether TEM or STEM), preparation of the sample can be delicate, time-consuming work. The term "TEM" as used herein refers to a TEM or an STEM and references to preparing a sample for a TEM are to be understood to also include preparing a sample for viewing on an STEM. The term "S/TEM" as used herein also refers to both TEM and STEM.
Several techniques are known for preparing TEM specimens. These techniques may involve cleaving, chemical polishing, mechanical polishing, or broad beam low energy ion milling, or combining one or more of the above. The disadvantage to these techniques is that they are not site-specific and often require that the starting material be sectioned into smaller and smaller pieces, thereby destroying much of the original sample.
Other techniques generally referred to as "lift-out" techniques use focused ion beams to cut the sample from a substrate or bulk sample without destroying or damaging surrounding parts of the substrate. Such techniques are useful in analyzing the results of processes used in the fabrication of integrated circuits, as well as materials general to the physical or biological sciences. These techniques can be used to analyze samples in any orientation (e.g., either in cross-section or in plan view). Some techniques extract a sample sufficiently thin for use directly in a TEM; other techniques extract a "chunk" or large sample that requires additional thinning before observation. In addition, these "lift-out" specimens may also be directly analyzed by other analytical tools, other than TEM. Techniques where the sample is extracted from the substrate within the FIB system vacuum chamber are commonly referred to as "in-situ" techniques; sample removal outside the vacuum chamber (as when the entire wafer is transferred to another tool for sample removal) are call "ex-situ" techniques.
Samples which are sufficiently thinned prior to extraction are often transferred to and mounted on a metallic grid covered with a thin electron transparent film for viewing. FIG. 1 shows a sample mounted onto a prior art TEM grid 10. A typical TEM grid 10 is made of copper, nickel, or gold. Although dimensions can vary, a typical grid might have, for example, a diameter of 3.05 mm and have a middle portion 12 consisting of cells 14 of size 90×90 μm2 and bars 13 with a width of 35 μm. The electrons in an impinging electron beam will be able to pass through the cells 14, but will be blocked by the bars 13. The middle portion 12 is surrounded by an edge portion 16. The width of the edge portion is 0.225 mm. The edge portion 16 has no cells, with the exception of the orientation mark 18. The thickness 15 of the thin electron transparent support film is uniform across the entire sample carrier, with a value of approximately 20 nm. TEM specimens to be analyzed are placed or mounted within cells 14.
During the extraction process, the wafer containing the completed lamella is removed from the FIB and placed under an optical microscope equipped with a micromanipulator. A probe attached to the micromanipulator is positioned over the lamella and carefully lowered to contact it. Electrostatic forces will attract lamella to the probe tip. The probe tip with attached lamella is then typically moved to a TEM grid. Alternatively, the attachment of the lamella to the probe tip can be done using FIB deposition.
Samples which require additional thinning before observation are typically mounted directly to a TEM sample holder. FIG. 2 shows a typical TEM sample holder 31, which comprises a partly circular 3 mm ring. In some applications, a sample 30 is attached to a finger 32 of the TEM sample holder by ion beam deposition or an adhesive. The sample extends from the finger 32 so that in a TEM (not shown) an electron beam will have a free path through the sample 31 to a detector under the sample. The TEM sample is typically mounted horizontally onto a sample holder in the TEM with the plane of the TEM sample perpendicular to the electron beam, and the sample is observed.
Unfortunately, preparation of TEM samples using such prior art methods of sample extraction are time consuming. Conventional work flow usually has a user pick up one sample at a time and placed on the TEM sample holder. First, the sample is prepped. Using a micromanipulator, the sample is lifted out. The sample is then moved to a sample holder, positioned, and then lowered so the electrostatic forces will "drop off" the sample. The sample can also be removed and placed on the location of a TEM sample holder by physically severing the connection. CD metrology often requires multiple samples from different locations on a wafer to sufficiently characterize and qualify a specific process. In some circumstances, for example, it will be desirable to analyze from 15 to 50 TEM samples from a given wafer. When so many samples must be extracted and measured, using known methods the total time to process the samples from one wafer can be days or even weeks. Even though the information that can be discovered by TEM analysis can be very valuable, the entire process of creating and measuring TEM samples has historically been so labor intensive and time consuming that it has not been practical to use this type of analysis for manufacturing process control. For the user to prep and remove each of the TEM samples, the user must perform these steps repeatedly. In other words, the user repeats the steps of prepping another sample. The user then repeats the step of lifting the sample out. Then, the user moves the sample to the TEM sample holder one at a time. This current process for high volume TM lamella prep is performed serially, and the process is often time consuming and labor intensive.
Speeding up the process of sample extraction and transfer would provide significant advantages in both time and potential revenue by allowing a semiconductor wafer to be more rapidly returned to the production line. What is needed is an improved method for TEM sample analysis, including new ways of extracting more than one sample at a time.

Multiple sample attachment to nano manipulator for high throughput sample preparation


An apparatus and method for manufacturing a drainage line unit. The apparatus includes a mandrel having an inner cavity. Rear, upper and front openings communicate with the mandrel cavity. Preferably, a controller connected to at least one sensor is operably positioned to control the apparatus. A pipe feeder feeds perforated vent pipe through the inner cavity of the mandrel from the rear opening to the front opening and therethrough. The pipe is positioned within the inner tube cavity so as to define a void space between the pipe and the wall of the mandrel. A hopper assembly has an exit port positioned for feeding a plurality of plastic bodies into the cavity. A blower produces a sufficient air flow through the mandrel cavity for moving the plurality of plastic bodies to substantially fill the void space so that the pipe emerges from the front opening of the mandrel surrounded by the plurality of plastic bodies. A sleeve feeder feeds a continuous sleeve of netting over the plurality of plastic bodies and the vent pipe emerging through the front opening of the mandrel to form a drainage line. A separator is positioned downstream from the front opening for fastening the continuous sleeve of netting to the vent pipe as the pipe emerges through the front opening of the mandrel, so as to substantially encase the plurality of plastic bodies around the vent pipe. Following the fastening operation, the separator cuts the drainage line, thereby forming a completed drainage line unit.

The present invention relates to the field of drainage line units and, more particularly, to machines and methods for the manufacture thereof.
Drainage line units have been available for a number of years. Various U.S. patents describe such units, as well as an apparatus for manufacturing the units, for example, machines for manufacturing drainage lines have been previously described in U.S. Pat. No. 5,154,543. Also, the drainage line units best suited for production by the apparatus of the present invention are as previously described in U.S. Pat. Nos. 5,015,123, 5,051,028, 5,154,543, 5,535,499 (the ""499 patent) and 5,657,527 (the ""527 patent).
The previously disclosed and patented apparatus for fabricating the drainage line units, shown in the ""527 and ""499 patents, relied on machines using mechanical means to push an artificial aggregate material through a mandrel into a sleeve of netting to form the drainage units. The preferred artificial aggregate has been polystyrene or other poly-resinous material, however, as described in the ""527 patent, these materials exhibit a high coefficient of friction, which makes it difficult to move this material through a conduit in a manufacturing operation. Mechanical means of pushing the aggregate included a hydraulically operated piston device and a screw drive auger, as shown in FIG. 15 of the ""527 patent.
Experience with the manufacturing equipment shown in attached FIGS. 13, 14 and 15 of the ""527 has shown that when using polystyrene and similar poly-resinous materials for the aggregate 21, the aggregate exhibits a high degree of surface friction when compacted by operation of the reciprocating hydraulic piston 101. To this end, it has been determined that the direction of compaction is not only longitudinally along the length of the mandrel 91, or conduit, but also that the nature of polystyrene and other poly-resinous materials is such as to expand outwardly into a high friction engagement with the inner surface of the conduit (mandrel 91). This problem occurs no only at the exit end of the mandrel 91, but also at intermediate points along its length, as is depicted in the cross-sectional side view of FIG. 18. In order to solve these problems, it was determined that the application of a low friction coating 250 along the inside surface of the mandrel 91, or conduit, substantially reduces the friction produced by the aggregate material inside the mandrel or conduit. Suitable low friction coatings include a silicone lubricant, or a deposited coating of a low friction polyresin such as nylon or Teflon(copyright) (a trademark of the DuPont Company). The use of the low friction coating dramatically increased the speed at which the hydraulic piston of the prior art could be reciprocated, thereby increasing the productivity of each manufacturing machine.
Rather than being directed at mitigating friction, the present invention overcomes the problems altogether through a new process, thereby resulting in much improved production rates and eliminating the need for lubricants or other means of mitigating friction between the poly-resinous material and the manufacturing equipment.
With the foregoing in mind, the present invention advantageously provides an apparatus for manufacturing a drainage line unit.
The present invention comprises transporting the poly-resinous aggregate material, such as polystyrene, through a conduit by creating a high velocity air flow within the conduit, thereby to pick up and transport the aggregate bodies through the conduit and within the air stream. The preferred aggregate is a light-weight material such as expanded polystyrene, other poly-resinous plastics, and any other light-weight materials suitable for crush protection in packaging and of an approximate size of xc2xe to one inch bodies, an example of which is the plastic foam material popularly known as xe2x80x9cpacking peanutsxe2x80x9d.
The high-velocity air flow provides a number of advantages over mechanical conveyance means. A high-velocity air flow lifts and carries the aggregate bodies through the conduit without producing significant friction. Less friction means that less heat is generated during operations. While mechanical conveyance devices, such as the piston or auger drives previously described, tend to produce breakage of the aggregate bodies, such effect is minimized when the means of conveyance is an air flow, therefore more of the aggregate is usable for the manufacturing application. In addition, a high-velocity air flow is produced more efficiently than driving mechanical means, using less energy, and therefore results in a less expansive manufacturing operation.
The apparatus of the present invention includes a support frame, a mandrel preferably shaped in the form of a tube and horizontally positioned on the support. The mandrel has a tube wall which defines an inner cavity, and includes rear, upper and front openings which communicate with the cavity. A controller connects to at least one sensor positioned relative to a direction of manufacture so as to provide sensing information to the controller, the controller operably connected to control the apparatus responsively to the sensing information. A pipe feeder feeds a predetermined length of perforated vent pipe through the inner cavity of the mandrel in a direction of manufacture from the rear opening to the front opening and therethrough. The pipe extends into the inner cavity so as to define a void space between the pipe and the wall of the mandrel. A hopper assembly connects to the mandrel and has an exit port positioned in communication with the inner cavity for therethrough feeding a plurality of plastic bodies into the cavity. A blower connects in communication with the inner cavity of the mandrel for producing a sufficient air flow therethrough for moving the plurality of plastic bodies to substantially fill the void space so that the pipe emerges from the front opening of the mandrel surrounded by the plurality of plastic bodies. A sleeve feeder connects to the mandrel for feeding a continuous sleeve of netting over the plurality of plastic bodies and the vent pipe emerging thorough the front opening of the mandrel, thereby substantially encasing the plurality of plastic bodies around the vent pipe to form a drainage line. A separator connects in responsive communication with the controller, and is positioned relative to the direction of manufacture downstream from the sleeve feeder for fastening the continuous sleeve of netting to the vent pipe as the pipe emerges through the front opening of the mandrel, so as to substantially encase the plurality of plastic bodies around the vent pipe. Following the fastening operation, the separator cuts the continuous sleeve, thereby forming a drainage line unit.

Apparatus for manufacturing drainage line units and associated methods