Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09J133/08—Homopolymers or copolymers of acrylic acid esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/04—Non-macromolecular additives inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09J133/062—Copolymers with monomers not covered by C09J133/06
  • C09J133/064—Copolymers with monomers not covered by C09J133/06 containing anhydride, COOH or COOM groups, with M being metal or onium-cation
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/24—Homopolymers or copolymers of amides or imides
  • C09J133/26—Homopolymers or copolymers of acrylamide or methacrylamide
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/10—Adhesives in the form of films or foils without carriers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/22—Plastics; Metallised plastics
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
  • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C09J7/385—Acrylic polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0025—Crosslinking or vulcanising agents; including accelerators
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/314—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive layer and/or the carrier being conductive
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2433/00—Presence of (meth)acrylic polymer

Definitions

• PSA article with at least one layer of a thermally conductive PSA and process for its production
• the invention relates to a method for producing a pressure-sensitive adhesive article which has at least one layer of a thermally conductive pressure-sensitive adhesive, and to a pressure-sensitive adhesive article obtainable in this way, in particular for bonds in the field of electrical and electronic components.
• No. 6,228,965 describes an acrylate copolymer mixture which in turn is mixed with a heat-conductive material. In this way there are also heat Conductive acrylic PSAs are accessible, which can be used for bonding without great pressure.
• the solution to the problem of the invention comprises a method for producing a pressure-sensitive adhesive article for the bonding of electrical or electronic parts, which has at least one layer made of a thermally conductive pressure-sensitive adhesive, ie a pressure-sensitive adhesive based on polyacrylates and / or polymethacrylates with, if appropriate, further comonomers.
• a thermally conductive pressure-sensitive adhesive ie a pressure-sensitive adhesive based on polyacrylates and / or polymethacrylates with, if appropriate, further comonomers.
• an at least one property anisotropic layer is produced from the thermally conductive PSA, which in at least one direction along the layer plane has a shrinkback of at least 3% with respect to the length dimension of the layer, measured using a shrinkback measurement Test B on free film.
• Anisotropy means that at least one property of the PSA in one spatial direction within the layer of PSA differs from the same property in at least one other direction; that is, anisotropic characteristics are vectorial
• the PSA has an orientation as known as such, i.e. a preferred direction within the polymer structure.
• the coating process can be, for example, a "hot melt” or hot melt roll coating process, a melt nozzle coating process or an extrusion coating process.
• the coating method is a conventional coating method, for example from solution, in which stretching or stretching is carried out after the coating, preferably on a stretchable carrier.
• the thermally conductive PSA can be coated on one or both sides with the coating method onto a sheet-like or tape-like carrier, which can also be a transfer tape or a release liner.
• the carrier material can itself be thermally conductive.
• Anisotropic PSAs are known as such. In the following, they are also referred to as anisotropically oriented or simply “oriented PSAs”.
• Anisotropically oriented PSAs tend to move back to their original state after being stretched in a given direction by the "entropy-elastic behavior”.
• (meth) acrylate PSAs are preferably used as PSAs, or PSAs on polyacrylate and / or polymethacrylics. lat based, ie with a substantial or predominant proportion of polyacrylate and / or polymer methacrylates including associated derivatives.
• the monomers are preferably chosen such that the resulting polymers can be used as pressure-sensitive adhesives at room temperature or higher temperatures, in particular in such a way that the resulting polymers have pressure-sensitive adhesive properties in accordance with the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989).
• the molecular weights M w of the polyacrylates used are preferably M w > 200,000 g / mol.
• acrylic or methacrylic monomers which consist of acrylic and methacrylic acid esters with alkyl groups of 4 to 14 carbon atoms, preferably comprising 4 to 9 carbon atoms.
• Specific examples are methacrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n -Nonylacrylat, laurylacrylate, stearyl acrylate, behenyl acrylate, and their branched isomers, such as Isobutyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooct
• cycloalkyl alcohols consisting of at least 6 carbon atoms.
• the cycloalkyl alcohols can also be substituted, e.g. by C-1-6 alkyl groups, halogen atoms or cyano groups.
• Specific examples are cyclohexyl methacrylate, isobomylacrylate, isobornyl methacrylate and 3,5-dimethyladamantylacrylate.
• monomers which contain polar groups such as carboxyl residues, sulfonic and phosphonic acid, hydroxy residues, lactam and lactone, N-substituted Amide, N-substituted amine, carbamate, epoxy, thiol, alkoxy. Wear cyan residue, ether or similar.
• Moderate basic monomers are e.g. N, N-dialkyl substituted amides such as e.g. N, N-dimethylacrylamide, NN-dimethylmethyl methacrylamide, N-tert.-butylacrylamide, N-vinyl-pyrrolidone, N-vinyl lactam, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, N-methylol methacrylic amide, N (methylol methacrylic amide) N- (Ethoxymethyl) acrylamide, N-isopropylacrylamide, although this list is not exhaustive.
• N, N-dialkyl substituted amides such as e.g. N, N-dimethylacrylamide, NN-dimethylmethyl methacrylamide, N-tert.-butylacrylamide, N-vinyl
• vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds with aromatic cycles and heterocycles in the ⁇ -position are used as co-monomers.
• photoinitiators with a copolymerizable double bond are used for the polymerization of the poly (meth) acrylate PSA.
• Norrish-I and -Il photoinitiators are suitable as photoinitiators. Examples are, for example, benzoin acrylate and an acrylated benzophenone from UCB (Ebecryl P 36 ® ).
• all photoinitiators known to the person skilled in the art can be copolymerized, which can crosslink the polymer via a radical mechanism under UV radiation.
• Aromatic vinyl compounds such as, for example, styrene, are suitable as components, the aromatic nuclei preferably consisting of C 4 to C 18 building blocks and also being able to contain heteroatoms.
• Particularly preferred examples are 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, 4-vinylbenzoic acid, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, t-butylphenyl acrylate, t-butylphenyl methacrylate, 4-biphenyl acrylate and 2-methacrylate Naphylacrylate and methacrylate as well as mixtures of those monomers, although this list is not exhaustive.
• a shrinkback of at least 3% is generated in the PSA, the shrinkback being measured by a determination according to test B (shrinkback measurement in the free film).
• PSAs are used in which the shrinkback is at least 30%, very preferably at least 50%.
• the thermally conductive PSA used in the invention preferably contains an addition of a thermally conductive compound.
• thermally conductive filling materials are therefore used. Suitable fillers are e.g. various metal particles, ceramics, aluminum oxide, aluminum nitride, titanium boride, boron nitride, silicon nitride. However, all other thermally conductive materials known to the person skilled in the art can also be added.
• the tack always has to be guaranteed.
• the thermal conductivity of the PSA should be at least 0.05 W / mK. In a preferred configuration, the thermal conductivity in the orientation direction is lower than in the transverse direction.
• Resins may be added to the inventive PSAs for further development. All of the previously known adhesive resins described in the literature can be used as tackifying resins to be added. Representative are the pinene, indene and rosin resins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene-phenolic resins as well as C5, C9 and other hydrocarbon resins. Any combination of these and other resins can be used to set the properties of the resulting adhesive as desired.
• all (soluble) resins compatible with the corresponding polyacrylate can be used, in particular reference is made to all aliphatic, aromatic, alkylaromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins and natural resins. Attention is drawn to the presentation of the state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989).
• plasticizers plasticizers
• other fillers such as fibers, carbon black, zinc oxide, chalk, solid or hollow glass spheres, microspheres made of other materials, silica, silicates), nucleating agents, blowing agents
• compounding agents and / or anti-aging agents can optionally be used , e.g. in the form of primary and secondary antioxidants or in the form of light stabilizers.
• the PSA can be crosslinked immediately after or during the hot-melt coating, preferably photochemically, which additionally stabilizes the oriented state, so that the PSA undergoes practically no change even over longer storage times under non-optimal conditions.
• crosslinkers and promoters can be added for crosslinking.
• Suitable crosslinkers for electron beam crosslinking and UV crosslinking are, for example, bi- or multifunctional acrylates, bi- or multifunctional isocyanates (also in blocked form) or bi- or multifunctional epoxies.
• the polyacrylate PSAs can be used for optional crosslinking with UV light
• UV-absorbing photoinitiators can be added.
• Useful photoinitiators that are very easy to use are benzoin ethers, such as. B. benzoin methyl ether and ben- zoinisopropyl ether, substituted acetophenones, such as. B. 2,2-Diethoxyacetpphenone (available as Irgacure 651 ® from Ciba Geigy ® ), 2,2-dimethoxy-2-phenyl-1-phenylethanone, dimethoxyhydroxyacetophenone, substituted ⁇ -ketols, such as. B. 2-methoxy-2-hydroxypropiophenone, aromatic sulfonyl chlorides, such as. B. 2-naphthyl sulfonyl chloride, and photoactive oximes such.
• the above-mentioned and other usable photoinitiators and others of the Norish I or Norrish II type may contain the following radicals: benzophenone, acetophenone, benzil, benzoin, hydroxyalkylphenone, phenylcyclohexyl ketone, anthraquinone, trimethylbenzoylphosphine oxide, methylthiopetonyl -, Aminoketone, azobenzoin, thioxanthone, hexarylbisimidazole, triazine, or fluorenone, each of these radicals being additionally substituted with one or more halogen atoms and / or one or more alkyloxy groups and / or one or more amino groups or hydroxy groups can.
• the monomers are chosen such that the resulting polymers can be used as pressure-sensitive adhesives at room temperature or higher temperatures, in particular in such a way that the resulting polymers have pressure-sensitive adhesive properties in accordance with the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand , New York 1989).
• the monomers are very preferably selected in accordance with what has been said above, and the quantitative composition of the monomer mixture is advantageously chosen such that the Fox equation (G1) (cf. TG Fox, Bull. Am. Phys. Soc. 1 (1956) 123) gives the desired T G value for the polymer.
• n represents the running number of the monomers used
• w n the mass fraction of the respective monomer n (% by weight)
• T G the respective glass transition temperature of the homopolymer from the respective monomers n in K.
• radical polymerizations are advantageously carried out to prepare the poly (meth) acrylate PSAs.
• initiator systems are preferably used which additionally contain further radical initiators for the polymerization, in particular thermally decomposing radical-forming azo or peroxo initiators.
• thermally decomposing radical-forming azo or peroxo initiators In principle, however, all of the usual initiators known to those skilled in the art for acrylates are suitable.
• C-centered radicals is described in Houben Weyl, Methods of Organic Chemistry, Vol. E 19a, pp. 60 - 147. These methods are preferably used in analogy.
• radical sources are peroxides, hydroperoxides and azo compounds
• typical radical initiators are potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, azodiisoic acid butyronitrile, cyclohexyl peroxylacetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxydiphenyl peroxo tyl peroxyl peroxo tyl peroxo tol peroxo tyl peroxo tol peroxo tol peroxo butyl peroxo tol peroxo tyl peroxo tol peroxo tetra peroxo.
• 1'-azobis 1'-azobis
• the thermally conductive materials can be added to the monomers before the polymerization and / or after the end of the polymerization.
• the average molecular weights Mw of the PSAs formed in the radical polymerization are very preferably chosen such that they are in a range from 200,000 to 4,000,000 g / mol; PSAs with average molecular weights M w of 400,000 to 1,400,000 g / mol are produced specifically for further use as thermally conductive hotmelt PSAs with anisotropic behavior.
• the average molecular weight is determined using size exclusion chromatography (GPC) or matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS).
• the polymerization can be carried out in bulk, in the presence of one or more organic solvents, in the presence of water or in mixtures of organic solvents and water.
• Suitable organic solvents are pure alkanes (e.g. hexane, heptane, octane, isooctane), aromatic hydrocarbons (e.g. benzene, toluene, xylene), esters (e.g. ethyl acetate, propyl, butyl or hexyl acetate), halogenated hydrocarbons (e.g. chlorobenzene) , Alkanols (for example methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether) and ethers (for example diethyl ether, dibutyl ether) or mixtures thereof.
• alkanes e.g. hexane, heptane, octane, isooctane
• aromatic hydrocarbons e.g. benzene, toluene, xylene
• esters e.g. ethyl
• a water-miscible or hydrophilic cosolvent can be added to the aqueous polymerisation reactions in order to ensure that the reaction mixture is in the form of a homogeneous phase during the monomer conversion.
• Advantageously usable cosolvents for the present invention are selected from the following group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinos, N-alkylpyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, Organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxy ether derivatives, amino alcohols, ketones and the like, as well as derivatives and mixtures thereof.
• the polymerization time is - depending on the conversion and temperature - between 2 and 72 hours.
• the entry of heat is essential for the thermally decomposing initiators.
• the polymerization can be initiated for the thermally decomposing initiators by heating to 50 to 160 ° C., depending on the type of initiator.
• the prepolymerization technique is particularly suitable here.
• the polymerization is initiated with UV light, but only leads to a low conversion of approximately 10 to 30%.
• This polymer syrup can then be welded into foils (in the simplest case, ice cubes) and then polymerized through in water to a high conversion.
• These pellets can then be used as acrylic hot melt adhesives, with film materials being particularly preferred for the melting process are used that are compatible with the polyacrylate.
• the thermally conductive material additives can be added before or after the polymerization.
• poly (meth) acrylate PSAs Another advantageous production process for the poly (meth) acrylate PSAs is anionic polymerization.
• Inert solvents are preferably used as the reaction medium, e.g. aliphatic and cycloaliphatic hydrocarbons, or also aromatic hydrocarbons.
• the living polymer is generally represented by the structure P L (A) -Me, where Me is a Group I metal, such as lithium, sodium or potassium, and P L (A) is a growing polymer block from the monomers A. is.
• the molar mass of the polymer to be produced is controlled by the ratio of the initiator concentration to the monomer concentration.
• Suitable polymerization initiators are, for. B. n-propyllithium, n-butyllithium, sec-butyllithium, 2-naphthyllithium, cyclohexyllithium or octyllithium, this list does not claim to be complete.
• Initiators based on samarium complexes for the polymerization of acrylates are also known (Macromolecules, 1995, 28, 7886) and can be used here.
• difunctional initiators such as 1,1,4,4-tetraphenyl-1,4-dilithiobutane or 1,1,4,4-tetraphenyl-1,4-dilithioisobutane.
• coinitiators can also be used. Suitable coinitiators include lithium thiurri halides, alkali metal alkoxides or alkyl aluminum compounds.
• the ligands and coinitiators are chosen so that acrylate monomers such as e.g. n-Butyl acrylate and 2-ethylhexyl acrylate can be polymerized directly and do not have to be generated in the polymer by transesterification with the corresponding alcohol.
• Controlled radical polymerization methods are also suitable for the production of polyacrylate PSAs with a narrow molecular weight distribution.
• a counterreagent of the general formula is then preferably used for polymerisation.
• R and R 1 are independently selected or the same
• C 2 -C 8 heteroalkyl radicals with at least one O atom and / or one NR * group in the carbon chain
• R * can be any (in particular organic) radical, with at least one ester group, amine group, carbonate group, Cyano group, I-socyano group and / or epoxy group and / or sulfur-substituted C -, - C 18 alkyl radicals, C 3 -C 18 alkenyl radicals, C 3 -C 8 alkynyl radicals; - C 3 -C 12 cycloalkyl radicals
• Control reagents of type (I) preferably consist of the following further restricted compounds:
• Halogen atoms are preferably F, Cl, Br or I, more preferably Cl and Br. Both alkyl and branched chains are outstandingly suitable as alkyl, alkenyl and alkynyl radicals in the various substituents.
• alkyl radicals which contain 1 to 18 carbon atoms are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, Nonyl, decyl, undecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.
• alkenyl radicals having 3 to 18 carbon atoms are propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl and isododecenyl and oleyl.
• alkynyl having 3 to 18 carbon atoms are propynyl, 2-butynyl, 3-butynyl, n-2-octynyl and n-2-octadecynyl.
• hydroxy-substituted alkyl radicals are hydroxypropyl, hydroxybutyl or hydroxyhexyl.
• halogen-substituted alkyl radicals are dichlorobutyl, monobromobutyl or trichlorohexyl.
• a suitable C 2 -C 18 heteroalkyl radical with at least one O atom in the carbon chain is, for example, -CH 2 -CH 2 -O-CH 2 -CH 3 .
• Cyclopropyl, cyclopentyl, cyclohexyl or trimethylcyclohexyl are used, for example, as C 3 -C 12 cycloalkyl radicals.
• C 6 -C 18 aryl radicals are phenyl, naphthyl, benzyl, 4-tert-butylbenzyl- or other substituted phenyl, such as, for example, ethyl, toluene, xylene, mesitylene, isopropylbenzene, dichlorobenzene or bromotoluene.
• phenyl, naphthyl, benzyl, 4-tert-butylbenzyl- or other substituted phenyl such as, for example, ethyl, toluene, xylene, mesitylene, isopropylbenzene, dichlorobenzene or bromotoluene.
• the above lists serve only as examples for the respective connection groups and are not exhaustive.
• R 2 can also be selected independently of R and R 1 from the group listed above for these radicals.
• nitroxide-controlled polymerizations can be carried out.
• radical stabilization nitroxides of type (Va) or (Vb) are used in a favorable procedure:
• R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 independently of one another denote the following compounds or atoms: i) halides, such as chlorine, bromine or iodine ii) linear, branched, cyclic and heterocyclic hydrocarbons with 1 to
• Compounds of (Va) or (Vb) can also be bound to polymer chains of any kind (primarily in the sense that at least one of the above-mentioned radicals represents such a polymer chain) and can thus be used to build up polyacrylate PSAs.
• US Pat. No. 4,581,429 A discloses a controlled radical polymerization process which uses a compound of the formula R'R "N-0 as initiator -Y uses, where Y is a free radical species that can polymerize unsaturated monomers, but the reactions generally have low conversions.
• Y is a free radical species that can polymerize unsaturated monomers, but the reactions generally have low conversions.
• the polymerization of acrylates which takes place in very low yields and molar masses, is particularly problematic.
• WO 98/13392 A1 describes open-chain alkoxyamine compounds which have a symmetrical substitution pattern.
• EP 735 052 A1 discloses a process for producing thermoplastic elastomers with narrow molar mass distributions.
• WO 96/24620 A1 describes a polymerization process in which very special radical compounds, such as, for example, phosphorus-containing nitroxides, are based on Imidazolidine ba sieren, be used.
• WO 98/44008 A1 discloses special nitroxyls which are based on morpholines, piperazinones and piperazinediones.
• DE 199 49 352 A1 describes heterocyclic alkoxyamines as regulators in controlled radical polymerizations.
• ATRP Atom Transfer Radical Polymerization
• the polyacrylate PSAs preferably monofunctional or difunctional secondary or tertiary halides as initiators and for the abstraction of the (r) halide (s) Cu, Ni, , Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au complexes
• the different possibilities of the ATRP are further described in the documents US 5,945,491 A, US 5,854,364 A and US 5,789,487 A.
• the polymers described above are preferably coated as hotmelt systems (ie from the melt). It may therefore be necessary for the manufacturing process to remove the solvent from the PSA.
• hotmelt systems ie from the melt.
• all methods known to the person skilled in the art can be used here.
• a very preferred method is the concentration over a
• twin screw extruders can be the same or not
• Vacuum stages distilled off In addition, depending on the distillation temperature of the solvent, counter-heating is carried out.
• the residual solvent proportions are preferably ⁇ 1%, more preferably ⁇ 0.5% and very preferably ⁇ 0.2%.
• the hot melt is processed from the melt.
• the orientation within the PSA is generated during the coating by the coating process.
• Different coating processes can be used for coating as a hot melt and thus also for orientation.
• the thermally conductive PSAs are coated using a roll coating process and the orientation is generated by stretching. Different roller coating processes are described in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989).
• orientation is achieved by coating via a melting nozzle.
• the orientation of the thermally conductive PSA can be generated here on the one hand by the nozzle design within the coating nozzle, or on the other hand by a stretching process after the nozzle emerges.
• the orientation is freely adjustable.
• the stretching ratio can be controlled, for example, by the width of the die gap. Stretching always occurs when the layer thickness of the pressure-sensitive adhesive film on the carrier material to be coated is less than the width of the nozzle gap.
• the orientation is achieved by the extrusion coating.
• the extrusion coating is preferably carried out with an extrusion die.
• the extrusion dies used can advantageously come from one of the following three categories: T-die, fish-tail die and bow-die.
• the individual types differ in the shape of their flow channel.
• the shape of the extrusion nozzle can also generate an orientation within the hotmelt PSA.
• orientation can also be achieved after stretching out the nozzle by stretching the pressure-sensitive adhesive tape film.
• an ironing nozzle on a carrier, in such a way that a polymer layer is formed on the carrier by a relative movement from nozzle to carrier.
• the time between the coating and the crosslinking is advantageously short. In a preferred procedure, crosslinking takes place after less than 60 minutes, in a more preferred procedure after less than 3 minutes, in an extremely preferred procedure in the in-line process after less than 5 seconds.
• the carrier material equipped with thermally conductive PSA can be a single-sided or double-sided adhesive tape.
• transfer tapes are produced. All siliconized or fluorinated films with a release effect are suitable as the carrier material. BOPP, MOPP, PET, PVC, PUR, PE, PE / EVA, EPDM, PP and PE are mentioned as examples of film materials. Release papers (glassine papers, kraft papers, polyolefinically coated papers) can also be used for transfer tapes. In the event that the backing material remains in the PSA (for example in the form of a backing film), a backing material which is likewise high is preferably used has thermal conductivity. In this case too, films can be used which contain, for example, boron nitrile, aluminum oxide or silicon nitrile. However, metal foils can also be used. Particularly preferred foils consist of aluminum, copper, stainless steel, metal alloys, etc.). Polysilicones are also suitable as the carrier film.
• the carrier material should be cooled directly by a roller during the coating.
• the roller can be cooled by a liquid film / contact film from the outside or from the inside or by a cooling gas.
• the cooling gas can also be used to cool the PSA emerging from the coating nozzle.
• the roller is wetted with a contact medium, which is then located between the roller and the carrier material. Preferred embodiments for implementing such a technique are described below. Both a melting die and an extrusion die can be used for this process.
• the roller is cooled to room temperature, in an extremely preferred procedure to temperatures below 10 ° C. The roller should also rotate.
• the roller is also used to crosslink the oriented PSA.
• UV crosslinking irradiation is carried out using short-wave ultraviolet radiation in a wavelength range from 200 to 400 nm, depending on the UV photoinitiator used, in particular using high-pressure or medium-pressure mercury lamps with a power of 80 to 240 W. /cm.
• the radiation intensity is adapted to the respective quantum yield of the UV photoinitiator, the degree of crosslinking to be set and the degree of orientation.
• thermally conductive and oriented PSA with electron beams.
• Typical radiation devices that can be used are linear cathode systems, scanner systems or segment cathode systems if they are electron beam accelerators.
• the typical acceleration voltages are in the range between 50 kV and 500 kV, preferably 80 kV and 300 kV.
• the spreading doses used range between 5 and 150 kGy, in particular between 20 and 100 kGy.
• the thermally conductive and oriented PSAs are coated onto a roller provided with a contact medium.
• the contact medium can in turn cool the PSA very quickly. It is then advantageous to laminate onto the carrier material later.
• a material can be used as the contact medium that is able to make contact between the PSA and the roller surface, in particular a material that fills the voids between the carrier material and the roller surface (for example, unevenness in the roller surface, bubbles).
• a rotating cooling roller is coated with a contact medium.
• a liquid is selected as the contact medium, e.g. Water.
• alkyl alcohols such as ethanol, propanol, butanol, hexanol are suitable as additives, without wishing to restrict the choice of alcohols by these examples.
• Long-chain alcohols, polyglycols, ketones, amines, carboxylates, sulfonates and the like are also very advantageous. Many of these compounds lower the surface tension or increase the conductivity.
• a reduction in the surface tension can also be achieved by adding small amounts of nonionic and / or anionic and / or cationic surfactants to the contact medium.
• commercial detergents or soap solutions can be used, preferably in a concentration of a few g / l in water as the contact medium.
• Special surfactants which can also be used at low concentrations, are particularly suitable. Examples include sulfonium surfactants (eg ⁇ -di (hydroxyalkyl) sulfonium salt), furthermore, for example, ethoxylated nonylphenylsulfonic acid ammonium salts or block copolymers, in particular diblocks.
• surfactants in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2000 Electronic Release, Wiley-VCH, Weinheim 2000.
• liquids can also be used as contact media without the addition of water, either individually or in combination with one another.
• the contact medium can improve the properties of the contact medium (for example, to increase shear resistance, reducing the transmission of surfactants or the like on the liner surface and thus improved cleaning possibilities' of the final product) the contact medium and / or the additives used further advanta- way of salts, gels and similar viscosity-increasing Additives are added.
• the roller can be macroscopically smooth or have a slightly structured surface. It has proven useful if it has a surface structure, in particular a roughening of the surface. The wetting by the contact medium can thereby be improved.
• the coating process runs particularly well if the roller can be tempered, preferably in a range from -30 ° C. to 200 ° C., very particularly preferably from 5 ° C. to 25 ° C.
• the contact medium will preferably be applied to the roller.
• a second roller, which receives the contact medium, can be used for the continuous wetting of the coating roller. But it is also possible that it is applied without contact, for example by spraying.
• a grounded metal roller is usually used, which absorbs the incident electrons and the resulting X-rays.
• the roller is usually covered with a protective layer. This is preferably selected so that it is well wetted by the contact medium. Generally the surface is conductive. However, it can also be cheaper to coat them with one or more layers of insulating or semiconducting material.
• a second roller advantageously with a wettable or absorbent one Surface, runs through a bath with the contact medium, is wetted or soaked with the contact medium and a film of this contact medium is applied or spread by contact with the roller.
• the PSA is coated and crosslinked directly on the roller provided with the contact medium.
• the methods and systems described for UV crosslinking and ES crosslinking can in turn be used for this.
• the thermally conductive and oriented PSA is then transferred to a carrier material.
• the carrier materials already cited can be used.
• the degree of orientation within the thermally conductive PSAs depends on the coating process.
• the orientation can e.g. controlled by the die and coating temperature and the molecular weight of the polymer.
• the degree of orientation is freely adjustable through the width of the nozzle gap.
• this stretching process can also be freely adjusted by the web speed of the decreasing carrier material.
• the orientation of the adhesive can be measured with a polarimeter, with infrared dichroism or with X-ray scattering. It is known that the orientation in acrylic PSAs in the uncrosslinked state is in many cases only retained for a few days. The system reiaxes in the resting or storage period and loses its preferred direction. This effect can be significantly enhanced by crosslinking after coating. The relaxation of the oriented polymer chains converges to zero, and the oriented PSAs can be stored for a very long time without losing their preferred direction.
• the degree of orientation is determined by measuring the shrinkback in the free film (see Test B).
• the orientation can also be generated after the coating.
• a stretchable carrier material is then preferably used here, in which case the PSA is also stretched when expanded.
• PSAs conventionally coated from solution or water can also be used.
• this stretched PSA is in turn crosslinked with actinic radiation.
• the invention relates to the use of the thermally conductive and oriented PSAs for the bonding of components in the electrical and electronics industry.
• the PSA tapes according to the invention are particularly preferably used for bonding cooling units to hot electrical or electronic components.
• the resilience of the PSA prevents or minimizes running out of the PSA in a preferred direction after the adhesive has been bonded. This process is accelerated by the temperature influence of the electrical / electronic component.
• the thermally conductive particles within the PSA are also oriented by the stretching and pulled apart in a preferred direction. This process reduces the thermal conductivity in the orientation direction, so that the PSAs and therefore also the corresponding PSA tapes generally have an anisotropic thermal conductivity.
• the pressure-sensitive adhesive tape according to the invention has no electrical conductivity.
• the average molecular weight M w and the polydispersity PD were determined using gel permeation chromatography. THF with 0.1% by volume of trifluoroacetic acid was used as the eluent. The measurement was carried out at 25 ° C. PSS-SDV, 5 ⁇ , 10 3 A, ID 8.0 mm ⁇ 50 mm was used as the guard column. The columns PSS-SDV, 5 ⁇ , 10 3 and 10 5 and 10 6 , each with an ID of 8.0 mm x 300 mm, were used for the separation. The sample concentration was 4 g / l, the flow rate 1.0 ml per minute. Measurements were made against PMMA standards.
• Strips of at least 30 mm were parallel to the coating direction of the hot melt
• Cut width and 20 cm length For bulk applications at 100 g / m 2 , 4 strips were laminated one above the other, at 50 g / m z 8 strips were laminated one above the other in order to obtain comparable layer thicknesses. The body obtained in this way was then cut to a width of exactly 20 mm and pasted with paper strips at the respective ends at a distance of 15 cm. The test specimen prepared in this way was then suspended vertically at RT and the change in length was followed over time until no further shrinkage of the sample could be determined. The initial length reduced by the final value was then given as a shrinkback in percent based on the initial length.
• the coated and oriented PSAs were stored over a longer period of time as a rag sample and then analyzed.
• the thermal conductivity was measured using the copper block method.
• the pressure-sensitive adhesive tape to be tested is stuck between two copper blocks. There will be two Temperatures at a distance of 5 and 15 mm from the surface measured and extrapolated to the surface temperature.
• Ni-CrNi thermocouples were used as thermal sensors.
• the measuring equipment is enclosed in PVC to avoid radiation losses.
• the heat is coupled in through an electrical heating element.
• the measuring device is cooled with a water cooler . Copper.
• the measuring bodies (PSA tapes) have a dimension of 25 mm x 25 mm. The pure PSA film without carrier was measured in each case.
• T 1 , T 2 temperatures at measuring points 1 and 2
• the thermal conductivity can be determined from this equation:
• ⁇ HK ⁇ cu • s Pr (T1 - T 2 ) / s • (Tu - T 0 )
• a 20 mm wide strip of an acrylic PSA coated on a polyester or siliconized release paper was applied to steel plates. Depending on the direction and stretching, longitudinal or transverse patterns were glued to the steel plate.
• the pressure-sensitive adhesive strip was pressed onto the substrate twice with a 2 kg weight.
• the adhesive tape was then immediately removed from the substrate at 30 mm / min and at a 180 ° angle.
• the steel plates were washed twice with acetone and once with isopropanol. The measurement results are given in N / cm and are averaged from three measurements. All measurements were carried out at room temperature under air-conditioned conditions.
• a conventional 200 L reactor for radical polymerizations was charged with 2400 g of acrylic acid, 64 kg of 2-ethylhexyl acrylate, 6.4 kg of N-isopropylacrylamide and 53.3 kg of acetone / isopropanol (95: 5). After passing through with nitrogen gas for 45 minutes while stirring, the reactor was heated to 58 ° C. and 40 g of 2,2'-azoisobutyronitrile (AIBN) were added. The outer heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this outside temperature. After a reaction time of 1 h, 40 g of AIBN were again added.
• AIBN 2,2'-azoisobutyronitrile
• a 200 L reactor conventional for radical polymerizations was charged with 1200 g of acrylic acid, 74 kg of 2-ethylhexyl acrylate, 4.8 kg of N-isopropylacrylamide and 53.3 kg of acetone / isopropanol (95: 5). After passing through with nitrogen gas for 45 minutes while stirring, the reactor was heated to 58 ° C. and 40 g of 2,2'-azoisobutyronitrile (AIBN) were added. The outer heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this outside temperature. After a reaction time of 1 h, 40 g of AIBN were again added.
• AIBN 2,2'-azoisobutyronitrile
• Polymer 1 was mixed with 5% by weight of graphite KS 6, based on the polymer content.
• Polymer 1 was mixed with 10% by weight of KS 6, based on the polymer content.
• Polymer 2 was mixed with 20% by weight of aluminum oxide hollow spheres, based on the polymer content.
• Polymer 2 was mixed with 10 wt .-% KS 6 based on the polymer content. i) Pattern production for determining the shrinkback
• the PSAs in solution were concentrated on a Bersdorff concentration extruder with a throughput of approx. 40 kg / h at a temperature of approx. 115 ° C.
• the residual solvent content after the concentration was less than 0.5% by weight.
• through a bracket extrusion die with a die gap of 300 ⁇ m and a coating width of 33 cm at a specific coating temperature (melt temperature) at a web speed of 10 m / min onto a layer coated with 1.5 g / m 2 silicone (polydimethylsiloxane) 12 ⁇ m PET film coated.
• a stretching ratio of 3: 1 With a mass application of 100 g / m 2 (approx. 100 ⁇ m thick PSA layer), a stretching ratio of 3: 1, with a mass application of 50 g / m 2 (approx. 50 ⁇ m thick PSA layer), a stretching ratio of 6: 1 set.
• the siliconized PET film is passed over a co-rotating steel roller cooled to 5 ° C. At the point of contact of the PSA film on the PET film, the PSA film is thus cooled down immediately.
• the mass application was 50 or 100 g / m 2 .
• the pressure-sensitive adhesive tape is then crosslinked with electron beams after a path of approximately 5 m.
• Test B was carried out to determine the shrinkback.
• Test C was carried out to determine the thermal conductivity.
• the adhesive strength was determined according to test D.
• a first step two polymers with an average molecular weight M of approximately 800,000 g / mol were produced.
• Examples 1-4 according to the invention were produced with these PSAs.
• graphite and, on the other hand, hollow aluminum spheres were chosen as the thermally conductive materials.
• the degree of orientation of the individual PSAs was determined in a first investigation. Therefore, the shrinkback in the free film was determined in the following according to test method B. The measured values are summarized in Table 1.
• Table 2 Overview of the determined thermal conductivities according to test C.
• thermal conductivities were determined with a layer thickness of 50 ⁇ m.
• the thermal conductivities of base polymers 1 and 2 were also included. It can be seen from Table 2 that the examples according to the invention have good thermal conductivity and in all cases lie above the base polymers 1 and 2.
• the thermal conductivity can be varied by adding the thermally conductive materials.

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