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
  • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
  • C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
  • C08F265/06—Polymerisation of acrylate or methacrylate esters on to polymers thereof

Definitions

• the invention relates to aqueous plastic dispersions which contain latex particles with a soft core material and a hard shell material, and to their production and their use for sealable coatings.
• Plastic dispersions for sealable coatings also known as heat-sealing lacquers or adhesives
• a heat seal adhesive is defined as an adhesive that is applied to surfaces as a dispersion adhesive, adhesive varnish or hot melt adhesive, dries before bonding and then with Opposite side is bonded by strong pressure with simultaneous brief exposure to heat (for example in a high-frequency field or in a hot press).
• EP-A 0 574 803 describes the use of an aqueous dispersion based on two copolymers with different glass transition temperatures, which differ by at least 5 ° C., as a heat seal lacquer with good blocking resistance and also described heat sealability.
• the dispersions disclosed have high acid contents in the range from 12 to 20% by weight, based on the total mass of both copolymers. It is known that highly hydrophilic coatings do not have good wet adhesion properties.
• DE-A 44 39 459 describes polymer dispersions which, because of the incorporation of so-called adhesive monomers with an amino, ureido or N-heterocyclic group, are suitable for the production of heat-sealable adhesive layers.
• this object is achieved in that amino groups, ureido groups and N-heterocycle group-free plastic dispersions are built up from latex particles with a soft core material and a hard shell material, the glass transition temperature of the core material being less than 20 ° C. and the glass transition temperature of the shell material being greater than 30 ° C is, and used for the production of the shell material as comonomers N-methylol (meth) acrylamide and / or their alkyl ethers.
• the invention relates to a heat seal adhesive containing latex particles with a core of a homo- or copolymer with a Glass transition temperature less than 20 ° C and a shell made of a copolymer with a glass transition temperature greater than 30 ° C, characterized in that the copolymer of the shell contains monomer units from the group N-methylolacrylamide, N-methylolmethacrylamide and their (C 1 -C 4 ) alkyl ethers , wherein the latex particles contain no monomer units with amino or ureido groups or N-heterocyclic groups.
• the core / shell structure described in this patent application is intended to include, regardless of the morphology of the latex particles to be detected, all copolymers which are prepared by radical aqueous emulsion polymerization in two successive stages, the core being defined in the first stage and the shell in the second stage is produced.
• the latex particles themselves preferably consist of 5 to 95% by weight, in particular 5 to 60% by weight, homopolymer or copolymer of the core, and preferably 95 to 5% by weight, in particular 95 to 40% by weight, of copolymer the shell, based in each case on the total mass of the latex particles.
• ⁇ , ⁇ -monoethylenically unsaturated free-radically polymerizable monomers preferably esters of 3 to 6 carbon atoms containing ⁇ , ⁇ -monoethylenically unsaturated mono- and dicarboxylic acids, for example acrylic acid, methacrylic acid
• acrylonitrile and methacrylonitrile as well as vinyl aromatics , for example styrene, ⁇ -methylstyrene and chlorostyrene.
• Monomers which have an increased solubility in water, in particular ⁇ , ⁇ -monoethylenically unsaturated carboxylic acids with preferably 3 to 6 carbon atoms, for example acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid, and also vinylsulfonic acid, acrylamidopropanesulfonic acid and their water-soluble salts, are in core and Shell material at most contained in modifying amounts. This is usually less than 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of the core and shell material.
• Crosslinking comonomers with two or more copolymerizable carbon double bonds in the molecule for example vinyl (meth) acrylate, allyl (meth) acrylate, diol acrylates such as ethylene glycol diacrylate, butanediol-1, 3-diacrylate, butanediol-1, 4-diacrylate, hexanediol-1, 6-diacrylate, methylenebis (meth) acrylamide and diallyl esters of fumaric, maleic and itaconic acid can be used in small amounts, usually 0 to 5.0% by weight, based on the total amount of the core and shell material.
• vinyl (meth) acrylate allyl (meth) acrylate
• diol acrylates such as ethylene glycol diacrylate, butanediol-1, 3-diacrylate, butanediol-1, 4-diacrylate, hexanediol-1, 6-diacrylate,
• epoxy-functional compounds for example glycidyl methacrylate and hydroxy-functional monoesters of dihydric alcohols and ⁇ , ⁇ -monoethylenically unsaturated carboxylic acids, for example hydroxyethyl, hydroxypropyl and hydroxybutyl (meth) acrylate.
• the shell material contains as comonomers N-methylol (meth) acrylamide and / or their (C 1 -C 4 ) alkyl ethers, for example N-methylolacrylamide, N-methylol methacrylamide, N- (iso-butoxymethyl) acrylamide and N- (isobutoxymethyl ) methacrylamide, preferably in amounts of 0.01 to 10.0% by weight, in particular 0.01 to 7.0% by weight, based on the total mass of the shell material.
• N-methylol (meth) acrylamide and / or their (C 1 -C 4 ) alkyl ethers for example N-methylolacrylamide, N-methylol methacrylamide, N- (iso-butoxymethyl) acrylamide and N- (isobutoxymethyl ) methacrylamide, preferably in amounts of 0.01 to 10.0% by weight, in particular 0.01 to 7.0% by weight, based on the total mass of the shell material.
• the core and shell material are preferably made up of two or more monomer units of the monomers listed below: methyl methacrylate, ethyl acrylate, n-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, styrene, acrylonitrile, acrylic acid, methacrylic acid, Hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-methylolacrylamide and N- (iso-butoxymethyl) acrylamide.
• N-methylolacrylamide and N- (iso-butoxymethyl) acrylamide are preferably used exclusively to build up the shell material.
• such monomer mixtures are used which give the respectively predetermined glass transition temperature for the core or shell material.
• the respective monomer composition for a given glass transition temperature can be calculated using the equation according to Fox (T. G. Fox, Bull. Am. Phys. Soc. (Ser. II) 1, 123 (1956)).
• the solids content of the plastic dispersions according to the invention is usually between 30 and 60% by weight, preferably 40 and 55% by weight.
• the invention also relates to a process for producing a heat-seal adhesive by free-radically initiated polymerization of ethylenically unsaturated monomers in a first stage to form a polymer phase with a glass transition temperature below 20 ° C.
• the plastic dispersions are prepared by the aqueous emulsion polymerization method in the presence of dispersants and free-radical polymerization initiators.
• the monomer or the monomer mixture of the first stage can be metered into the polymerization vessel in the form of an aqueous monomer emulsion in whole or in part or entirely in the course of the first polymerization stage in anhydrous form or in the form of an aqueous emulsion.
• the monomer or the monomer mixture second stage are copolymerized analogously to the possibilities already described in the first stage.
• N-methylol (meth) acrylamides or their (C r C 4 ) -alkyl ethers to be copolymerized according to the invention in the second stage can be mixed into the monomer or monomer mixture or in the corresponding monomer emulsion, added to the polymerization vessel or added separately and in parallel to the monomer or are metered into the monomer mixture or the corresponding monomer emulsion.
• both polymerization stages one works preferably at temperatures between 20 and 95 ° C, in particular 50 to 85 ° C.
• the polymerization is started in both stages by conventional free-radical initiators which are able to initiate free-radical emulsion polymerization.
• These can be initiators such as alkali or ammonium peroxydisulfates, azobisisobutyronitrile, 4,4-azobiscyanvaleric acid or their alkali salts, tert-butyl perpivalate, tert-butyl per-ethyl hexanoate or redox systems.
• reducing agents for example sodium pyrosulfite, sodium hydrogen sulfite, sodium dithionite or the sodium salt of hydroxymethanesulfinic acid or ascorbic acid, optionally in combination with heavy metal salts, for example Fe (II ) Sulfate.
• Suitable dispersants are the emulsifiers and protective colloids usually used in the implementation of free-radical aqueous emulsion polymerizations.
• Anionic, cationic and nonionic types are suitable as emulsifiers, the anionic and nonionic types being particularly preferred.
• the anionic emulsifiers can be the alkali or ammonium salts of alkyl, aryl or alkylarylsulfonates, sulfates, phosphates, phosphonates or compounds with other anionic end groups, which also include oligo or polyethylene oxide units between the hydrocarbon radical and the anionic group of these emulsifiers.
• Typical examples are sodium lauryl sulfate, sodium undecyl glycol ether sulfate, Sodium octylphenol glycol ether sulfate, sodium dodecylbenzenesulfonate, sodium umlauryl diglycol sulfate, ammonium tri-tert-butylphenol penta- or octaglycol sulfate and alkali metal salts of mono- and dialkylated diphenyloxide disulfonic acids, which are often used as technical mixtures D® (Chemical) Dow.
• Suitable nonionic emulsifiers are, for example, alkyl polyglycol ethers such as ethoxylation products of lauryl, oleyl or stearyl alcohol or of mixtures such as coconut fatty alcohol, alkylphenol polyglycol ethers such as ethoxylation products of octyl or nonylphenol, diisopropylphenol, triisopropylphenol or of di- or tri-tert, butyl or ethoxylated products proven by polypropylene oxide.
• alkyl polyglycol ethers such as ethoxylation products of lauryl, oleyl or stearyl alcohol or of mixtures such as coconut fatty alcohol
• alkylphenol polyglycol ethers such as ethoxylation products of octyl or nonylphenol, diisopropylphenol, triisopropylphenol or of di- or tri-tert, butyl or ethoxylated products proven by poly
• the dispersions should contain the customarily used amounts of up to 3% by weight, preferably up to 2% by weight, of ionic emulsifiers or up to 6% by weight, preferably up to 4 % By weight of nonionic emulsifiers do not significantly exceed, so that the water resistance of the polymer films is not adversely affected.
• Protective colloids that may be used are natural substances such as gum arabic, starch, alginates or modified natural substances such as methyl, ethyl, hydroxyalkyl or carboxymethyl cellulose or synthetic substances such as polyvinyl alcohol, polyvinylpyrrolidone or mixtures of such substances. Modified cellulose derivatives and synthetic protective colloids can preferably be used. However, the use of these protective colloids is possible only to a limited extent when using the monomer systems described, as is known to the person skilled in the art. The amounts which can be used are often small, for example 0.001 to 2% by weight. The tolerability and the type of addition must be checked on a case-by-case basis.
• the invention also relates to the use of the heat seal adhesive in sealable coatings, in particular on metal and plastic. Examples
• a mixture of 280 g of water, 4.0 g of sodium lauryl sulfate and 30 g of monomer emulsion 1 was placed in a reaction vessel and heated to 80 ° C. within 30 minutes with stirring. After reaching 80 ° C., 0.8 g of ammonium peroxydisulfate, dissolved in 5.0 g of water, was added. After a further 15 minutes, the remaining amount of monomer emulsion 1 and in parallel the initiator solution 1 were metered in continuously at a temperature of 80 ° C. ⁇ 2 ° C. over a period of 2 hours. After completion of the feed streams 1, the temperature at 80 ⁇ 2 ° C C was maintained for an additional 30 minutes.
• the metering of monomer emulsion 2 was then started. In parallel, the initiator solution 2 and the comonomer solution were dosed. The dosing time was 2 hours for all three feeds. The polymerization mixture was then stirred for a further hour at 80 ° C. ⁇ 2 ° C. and then cooled to room temperature. The dispersion was adjusted to a pH of 6.5 ⁇ 0.5 with 12.5% aqueous ammonia solution.
• the monomer emulsions 1 and 2 were prepared by adding the respective monomer mixture to the corresponding solution of water and emulsifier with vigorous stirring (high-speed stirrer).
• Monomer emulsion 1 Monomer emulsion 2:
• Initiator solution 1 Initiator solution 2:
• Dispersion KD2 was synthesized analogously to the specification of dispersion KD1. Changes regarding the type and quantity of raw material are listed below for the KD 2 dispersion.
• Monomer emulsion 1 Monomer emulsion 2:
• Initiator solution 1 Initiator solution 2:
• the dispersion VD1 was synthesized analogously to the instructions for dispersion KD1, but the dosage of the comonomer solution in stage 2 was dispensed with.
• a mixture of 428.6 g of water, 4.0 g of sodium lauryl sulfate and 30 g of the monomer emulsion 1 was placed in a reaction vessel and heated to 80 ° C. within 30 minutes with stirring. After reaching 80 ° C., 0.8 g of ammonium peroxydisulfate, dissolved in 5.0 g of water, was added. After a further 15 minutes, the remaining amount of monomer emulsion 1 and in parallel the initiator solution 1 were metered in continuously at a temperature of 80 ° C. ⁇ 2 ° C. over a period of 2 hours. When feeds 1 had ended, the temperature was kept at 80 ° C. ⁇ 2 ° C. for a further 30 minutes.
• the metering of monomer emulsion 2 was then started. In parallel, the initiator solution 2 was dosed. The dosing time was 2 hours for both feeds. The polymerization mixture was then left at 80 ° C. for a further hour Stirred 2 ° C and then cooled to room temperature. The dispersion was adjusted to a pH of 6.5 ⁇ 0.5 with 12.5% strength aqueous ammonia solution.
• the monomer emulsions 1 and 2 were prepared by adding the respective monomer mixture to the corresponding solution of water and emulsifier with vigorous stirring (high-speed stirrer).
• Monomer emulsion 1 Monomer emulsion 2:
• Initiator solution 1 Initiator solution 2:
• a mixture of 433.8 g of water, 4.0 g of sodium lauryl sulfate and 30 g of the monomer emulsion 1 was placed in a reaction vessel and heated to 80 ° C. within 30 minutes with stirring. After reaching 80 ° C., 0.8 g of ammonium peroxydisulfate, dissolved in 5.0 g of water, was added. After a further 15 minutes, the remaining amount of monomer emulsion 1 and, in parallel, the initiator solution 1 at a temperature of 80 ° C ⁇ 2 ° C was continuously over a Dosed for a period of 2 hours. When feeds 1 had ended, the temperature was kept at 80 ° C. ⁇ 2 ° C. for a further 30 minutes.
• the metering of monomer emulsion 2 was then started. In parallel, the initiator solution 2 was dosed. The dosing time was 2 hours for both feeds. The polymerization mixture was then stirred for a further hour at 80 ° C. ⁇ 2 ° C. and then cooled to room temperature. The dispersion was adjusted to a pH of 6.5 ⁇ 0.5 with 12.5% strength aqueous ammonia solution.
• the monomer emulsions 1 and 2 were prepared by adding the respective monomer mixture to the corresponding solution of water and emulsifier with vigorous stirring (high-speed stirrer).
• Monomer emulsion 1 Monomer emulsion 2:
• Initiator solution 1 Initiator solution 2:
• a 50 ⁇ m thick wet film of the dispersion to be tested was applied to the matt side of a 40 ⁇ m thick aluminum foil (household foil quality) applied.
• the wet film was then immediately dried in a forced air oven at 200 ° C for one minute. After cooling to room temperature, the coated aluminum foil was subjected to water storage for 30 minutes. After removing the film from the water bath, the coated side of the film was carefully dried with a soft absorbent paper.
• two strips of transparent pressure-sensitive adhesive tape (Scotch Magic Tape 810, 19 mm wide, item no. 11257, manufacturer: 3M) were glued across and applied intensively. Then one adhesive strip was slowly removed from the heat seal coating and the other was removed quickly by hand.
• the adhesion fracture behavior was assessed by determining the detached surface of the coating on the aluminum foil as a measure of the quality of the wet adhesion.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Graft Or Block Polymers (AREA)
• Adhesives Or Adhesive Processes (AREA)

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• 1997
  • 1997-03-12 DE DE19710109A patent/DE19710109A1/de not_active Withdrawn
• 1998
  • 1998-02-27 EP EP98913605A patent/EP0968236A1/de not_active Withdrawn
  • 1998-02-27 WO PCT/EP1998/001116 patent/WO1998040423A1/de not_active Application Discontinuation
  • 1998-02-27 JP JP53914598A patent/JP2001514688A/ja active Pending
  • 1998-03-11 ZA ZA982048A patent/ZA982048B/xx unknown

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