WO2009071499A1 - Microcapsules having radiation-induced release - Google Patents

Microcapsules having radiation-induced release Download PDF

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WO2009071499A1
WO2009071499A1 PCT/EP2008/066494 EP2008066494W WO2009071499A1 WO 2009071499 A1 WO2009071499 A1 WO 2009071499A1 EP 2008066494 W EP2008066494 W EP 2008066494W WO 2009071499 A1 WO2009071499 A1 WO 2009071499A1
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microcapsules
nm
wavelength range
di
compound
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PCT/EP2008/066494
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German (de)
French (fr)
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Tobias Joachim Koplin
Simon Nord
Ulrike Licht
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Basf Se
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02Making microcapsules or microballoons
    • B01J13/06Making microcapsules or microballoons by phase separation
    • B01J13/14Polymerisation; cross-linking
    • B01J13/16Interfacial polymerisation

Abstract

The present invention relates to a novel microcapsule comprising a capsule wall made of polyurea and a capsule core comprising a polyacrylate copolymer and at least one compound absorbing electromagnetic radiation of the wavelength range from 700 nm to 1 m, a method for the production thereof, the use thereof for radiation-induced release of polyacrylate copolymer, and microcapsule dispersions comprising said microcapsules, and a method for gluing at least two substrates.

Description

Microcapsules with radiation-induced release

description

The present invention relates to microcapsules comprising a capsule wall made of poly urea and a capsule core comprising a polyacrylate copolymer and at least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, a process for their preparation and their use for the radiation-induced release of polyacrylate copolymer.

Microcapsules are known in various embodiments and are used depending on the tightness of the capsule wall for very different purposes. For example, they are used to protect nuclear materials that are to be released only through controlled mechanical destruction of the capsule wall, as dyes for copy papers or encapsulated fragrances. In such application areas are known capsule wall materials based on gelatin, polyurethane, acrylates and methacrylates on Po lyharnstoffbasis and polyacrylate-based and. Other demands are placed on wall materials for vegetable or pharmaceutical active ingredients as the core materials, which require a permeability of the capsule wall, allowing controlled release and targeted transport of active ingredients.

The US 5,596,051 discloses microcapsules with a poly-n-butyl acrylate as a core material and a copolymer of methyl methacrylate and methacrylic anhydride as a wall material. The wall opening is effected by the addition of bases, the chemically dissolve the crosslinking or swell the anhydride groups and thus allow the exit of the adhesive resin.

DE 3918141 teaches microcapsules having capsule walls from difunctional acids or acid derivatives and hexamethylenetetramine or acetaldehyde-Derviaten as crosslinkers. The built-in hexamethylenetetramine or the Acetaldehydammoniak- derivative is thermolabile and therefore represents a weak point in the capsule wall which thermally induces the release of the active substance causes.

WO 91/12883 and WO 91/12884 teach photo- or thermo labile microcapsules having capsule walls of polyurea. In Wall Polymer azo or peroxide are present as predetermined breaking points, which triggered photochemically or thermally, lead to the opening of the capsule wall. The installation of such breaking points requires special monomers which do not allow any process control, especially not at higher temperatures.

WO 02/20683 teaches a microencapsulated acrylate adhesive, wherein the adhesive is only formed during the encapsulation. As wall materials are mentioned, among other ren polyurea resins and alkyl acrylate / acrylic acid copolymers. The release is carried out by pressure or heat, which is disadvantageous in that the parts to be bonded must be heated as a whole.

From the older European applications 06126997.3 and 06126994.0 thermally destructible microcapsules are known for a Kaschierklebstoffdispersion. The microcapsule walls described therein based on polymethyl methacrylate become permeable as a rule at temperatures above 60 0 C for the information contained in the core carbodiimides and so cause the post-crosslinking of the laminating adhesives.

WO 03/054102 describes adhesives containing at least one metal oxide in the form of superparamagnetic, nanoscale particles, as well as manufacture methods of heating such preparations for the purpose of adhesive bonds on the basis of these preparations or dissolve. Thus, according to one embodiment, the cure-inducing component such as a monomer or catalyst, in the form of microcapsules containing superparamagnetic, nanoscale particles as a capsule core is dispersed in an adhesive composition and released by irradiation.

A similar approach selects the WO 02/48278, which describes a 1 K-dosage form of a two-component adhesive, in which a component A is present microencapsulation encapsulates and the microcapsules B are dispersed in a matrix of the second component. By irradiation with light of wavelength 200-700 nm, the component A is released and the formed adhesive.

WO 2004/076578 teaches hot melt adhesives containing the near infrared absorbing dyes or pigments. The tack can be reactivated by irradiation in the near infrared range by energy is introduced at the irradiated areas until the hot melt has melted.

A particular problem is found in adhesives, as they are known label adhesives, as they are permanently tacky. If you process it, you need to protect the adhesive surface specially coated papers that only when the adhesive effect is desired, may be deducted. The protective papers are obtained as waste falling.

An object of the present invention was a new dosage form of pressure sensitive adhesives, which should make it possible to control the adhesive effect both in time and spatially targeted.

Accordingly, microcapsules were found comprising urea a capsule wall made of poly and a capsule core comprising a polyacrylate copolymer and Any artwork least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, also referred to below as an absorber. Further, a method has been found containing these microcapsules for their preparation and microcapsule dispersions. Furthermore, it was found that radiation-induced in this way comparable encapsulated polyacrylate copolymer can be released. Further, the application relates to a method for bonding at least two substrates.

The microcapsules of the invention comprise a capsule core and a capsule wall of polymer. The average particle size of the capsules weight means (by light scattering) is 0.5 to 50 microns, preferably 0.5 to 30 microns. The weight ratio of core capsule to capsule wall is generally from 50: 5. Preferred is a core / cladding ratio of 70: 50 to 95 30 to 95:. 5

The term includes both polyurea the reaction products of isocyanate with di- and / or polyamines which are reaction products of isocyanate with di- and / or Polyamidinen and the reaction products of isocyanate with mixtures of di- and / or polyamines and di- and / or Polyamidinen.

The basic principle of microencapsulation is based on the so-called interfacial polymerization or addition. In the interfacial polyaddition, in a first process step, a mixture of lipophilic substances to be encapsulated, one or more isocyanates, and optionally a lipophilic solvent is prepared and then mixed with a hydrophilic solvent and processed to form an emulsion. The continuous phase of the emulsion usually contains surface-active substances in order to avoid coalescence of the droplets. In this emulsion the lipophilic mixture discontinuous later dispersed phase and the hydrophilic solvent is the continuous phase. Unless it is in the hydrophilic solvent is water, the term oil-in-water emulsion is vividly. The emulsified droplets are doing a size that matches the size of the un- dangerous later microcapsules. To form the capsule wall are mixed in a second process step the emulsion with the wall capable of forming di- or polyamine and / or di- and / or polyamidine. The isocyanate to react in a position at the interface between the discontinuous and the continuous phase with the dissolved in the continuous phase di- or polyamine and / or di- and / or polyamidine to form the polymeric film.

The third step comprises the so-called after-treatment of the capsule dispersion freshly prepared. Here, under the control of temperature and residence time and optionally using further auxiliaries, the reaction between diisocyanate iso- and di- and / or polyamine di- completed and / or and / or polyamidine. A process for the preparation of microcapsules having polyurea walls is described for example in EP 227 562, respectively. A hydrophilic solvents both water and such aqueous mixtures is understood to mean the weight in addition to water up to 20 -.% Of a water-miscible organic solvent, such as Ci to C4 alkanols, especially methanol, ethanol, isopropanol or a cyclic ethers such as tetrahydrofuran included. Preferred hydrophilic solvent is water.

Suitable hydrophilic solvents are also ethylene glycol, glycerol, polyethylene glycols and butylene glycol, mixtures thereof and their mixtures with water or the aqueous mixtures listed above. are preferred as the hydrophilic solvent mixtures of these solvents with water.

The substances to be encapsulated are polyacrylate copolymer absorbers and optionally other additives such as plasticizers, tackifying resins, solvents, UV stabilizers and radical scavengers. The absorber is located, depending on the solubility in the lipophilic phase prior dispersed or in solution.

A polyacrylate is a polymer which is obtainable by free radical polymerization of acrylic monomers, among which includes methylacrylic be understood, and other copolymerizable monomers. Preferably, the polyacrylate copolymer is at least 40 wt .-% is more preferably at least 60 wt .-%, most preferably at least 80 wt .-% of Ci - C10 alkyl (meth) acrylates constructed. Called in particular Ci-Cs alkyl (meth) acrylates are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (methacrylate).

Other monomers from which the polyacrylate copolymer can be constructed, are for example vinyl esters of up to 20 carbon atoms-containing carboxylic acids, vinyl aromatics having up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of 1 to 10 carbon atoms containing alcohols, aliphatic hydrocarbons having 2 to 8 carbon atoms and 1 or 2 double bonds or mixtures of these monomers.

Suitable vinylaromatic compounds include vinyltoluene, o- and p-methylstyrene, o-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and, preferably, styrene. Examples of nitriles are acrylonitrile and methacrylonitrile.

The vinyl halides are chlorine-, fluorine- or bromine-substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride.

Vinyl ethers are for. As vinyl methyl ether or vinyl isobutyl ether. Vinyl ethers is preferably from 1 to 4 carbon atoms containing alcohols. As hydrocarbons having 2 to 8 C atoms and two olefinic double bonds are butadiene, isoprene and chloroprene.

Further monomers in particular, are monomers containing carboxylic acid, sulfonic acid or phosphonic. Carboxylic acid groups are preferred. Called for were. For example, acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid.

Further monomers are,. B. acrylate monomers containing hydroxyl groups, in particular Ci-Cio-hydroxyalkyl (meth) acrylates, (meth) acrylamide.

Furthermore, those phenyloxyethyl (meth) acrylate, Glydidylacrylat, dylmethacrylat glycidyl, amino (meth) acrylates such as 2-aminoethyl (meth) acrylate. Monomers which carry further functional groups apart from the double bond, z. As isocyanate, amino, hydroxy, amide or glycidyl, may such. B. improve adhesion to substrates.

Preference is given to UV radiation crosslinkable polyacrylate. The photoinitiator is attached in this preferred variant of the polyacrylate copolymer. By irradiation with high-energy light, in particular UV-light, the photoinitiator brings about crosslinking of the polymer, preferably by a chemical grafting reaction of the photoinitiator with a spatially adjacent polymer chain. In particular, crosslinking can be effected by insertion of a carbonyl group of the photoinitiator to an adjacent C-H bond to form a -CCOH grouping.

The polyacrylate copolymer preferably contains 0.0001 to 1 mol, more preferably 0.0002 to 0.1 mol, most preferably 0.0003 to 0.01 mol of the photoinitiator, or the effective as a photoinitiator, bound to the polymer molecule group, per 100 g polyacrylate copolymer.

The photoinitiator is preferably incorporated by free-radical copolymerization in the polymer chain. The photoinitiator preferably contains acrylic group to an acrylic or (meth).

Suitable copolymerizable photoinitiators are acetophenone or benzophenone derivatives containing at least one, preferably one ethylenically unsaturated group. The ethylenically unsaturated group is preferably an acrylic or methacrylic group.

The ethylenically unsaturated group may be directly bonded to the phenyl ring of the acetophenone or benzophenone derivative. In general, located between the phenyl ring and ethylenically unsaturated group is a spacer (spacers). The spacer group may for example have a molecular weight of up to 500, especially up to 300 or 200 g / mol.

Suitable acetophenone derivatives or benzophenone derivatives are described for example in EP-A-346 734, EP-A- 377 199 (1st claim), DE-A-4037079 (claim 1) and DE-A-3844444 (claim 1, described), and are disclosed by this reference into the present application. Preferred acetophenone derivatives and benzophenone derivatives are those in which the attachment of the spacer group to the phenyl ring via a carbonate group is carried out. Compounds of formula I are preferred:

Figure imgf000007_0001
wherein R 1 is an organic radical having up to 30 carbon atoms, R 2 stands for a hydrogen atom or a methyl group and R 3 is an optionally substituted phenyl group or a Ci-C4-alkyl group.

R 1 particularly preferably represents an alkylene group, particularly a C 2 alkylene group -CS-.

R 3 particularly preferably represents a methyl group or a phenyl group, very particularly preferably a phenyl group.

also acetophenone and benzophenone derivatives are preferably of the formula II

Figure imgf000007_0002
wherein R 3 and R 2 have the above meaning and R 4 may stand for:

a single bond is a radical R 1 having the above meaning for (-CH 2 -CH 2 -O) n,

NH

~ C n H -O- 2V

0 or, NH

^ C n H O-NH-

where n is an integer of 1 to 12

Particularly preferred compounds of the formula I.

The polyacrylate copolymer preferably has a K-value of 10 to 100, particularly preferably from 40 to 60, as measured in tetrahydrofuran (1% solution, 21 0 C). The K value according to Fikentscher is a measure of the molecular weight and viscosity of the polyvinyl lymerisats.

The glass transition temperature (T 9) of the polyacrylate is preferably - 60 to +10 0 C, particularly preferably -55 to 0 0 C, most preferably -55 to - 10 0 C. allows the glass transition temperature althermoanalyse by customary methods such Differenti- or differential scanning calorimetry (see, for example, ASTM 3418/82,. determine "midpoint temperature".

The polyacrylate can be prepared, if appropriate, of regulators, polymerization taking place at the usual temperatures in bulk, in emulsion, eg in water or liquid hydrocarbons, or in solution by copolymerizing the monomeric components using the conventional polymerization initiators, as well. Preferably, the polyacrylate copolymers are prepared by polymerization of monomers in solvents, especially in solvents with a boiling range of 50 to 150 0 C, preferably from 60 to 120 0 C using the customary amounts of polymerization initiators that are generally from 0.01 to 10, in particular at 0.1 to 4 wt .-% is based on the total weight of the monomers.

Preferred solvents for the polymerization include ketones, alkyl alcohols or alkylene LaCetate having a boiling point below 150 0 C (at 1 bar), such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), ethanol, i-butanol, i-propanol, methyl acetate, ethyl acetate, and aromatic hydrocarbons such as benzene, toluene or xylene.

As polymerization initiators in the solution, for example, azo compounds, ketone peroxides and alkyl considered.

The polyacrylate copolymer according to the invention employed can be used in bulk or in solution. Suitable lipophilic solvents which form with water a phase boundary is. Suitable solvents for polyacrylate are mentioned as examples:

a) aliphatic hydrocarbon compounds such as saturated or unsaturated Cio-C4o-hydrocarbons, branched or preferably linear, such as n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane , n-heneicosane, n-docosane, n-tricosane, n-tetracosane, n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, and cyclic carbonic bons, such as cyclohexane, cyclooctane, cyclodecane;

b) naphthalene aromatic hydrocarbon compounds such as benzene, naphthalene, biphenyl, o- or m-terphenyl, Ci-C4o-alkyl-substituted aromatic hydrocarbons such as toluene, xylene, dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexyl or decylnaphthalene;

c) saturated or unsaturated Cβ-Cso-fatty acids such as lauric, stearic, oleic or behenic acid, preferably eutectic mixtures of decanoic acid with, for example, myristic, palmitic or lauric acid;

d) fatty alcohols such as lauryl, stearyl, oleyl, myristyl, cetyl alcohol, mixtures such as coconut fatty alcohol, and the so-called oxo alcohols which are mylierung by hydroformylation of α-olefins and further reactions obtained;

e) C6-C3o-fatty amines such as decylamine, dodecylamine, tetradecylamine or hexadecimal cylamin;

f) esters such as Ci-Cio-alkyl esters of fatty acids, such as propyl, methyl stearate or methyl palmitate, and preferably cinnamate their eutectic mixtures or methyl;

g) natural and synthetic waxes such as montan acid waxes, montan ester waxes, carnauba wax, polyethylene wax, oxidized waxes, polyvinyl ether wax, ethylene-vinyl or hard waxes from Fischer-Tropsch processes;

h) halogenated hydrocarbons such as chlorinated paraffin, bromooctadecane, Brompenta- decane, Bromnonadecan, Bromeicosan or bromodocosane and

i) natural oils such as peanut oil, soybean oil. Also suitable are solvents which form their solutions of polyacrylate copolymer in admixture with water, a phase boundary. in general, the presence of these solvents has an advantageous viscosity reduction result. For example, the solvent of the group k) are mentioned:

k) ketones or alkyl acetates having a boiling point below 150 0 C (at 1 bar), such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl acetate or ethyl acetate.

According to a preferred embodiment, a solvent is chosen that is also suitable for the preparation of the polyacrylate copolymers, that is suitable as solvents in the polymerization of the monomers. mentioned under a), b) and k) solvents and mixtures of these solvents are particularly preferred.

Of course, it is also possible for the polymerization polyacrylate copolymer carried out in another solvent and then to replace the solvent.

The polyacrylate can be used as 20-99 wt .-% solutions, preferably 50-90 wt .-% solutions in those listed in groups a) to k) solvents are used.

According to a preferred embodiment, the lipophilic mixture is solvent-free and contains only the polyacrylate copolymer, the compound that electromagnetic radiation from the wavelength range of 700 nm to 1 m, particularly preferably from> 700 nm to 1 m absorbed (absorber), and optionally auxiliaries. According to another embodiment the lipophilic mixture containing polyacrylate copolymer, the absorber, the solvent, preferably lipophilic solvent, and optionally excipients.

Preferably, the absorbers are incorporated into the polyacrylate copolymer.

Suitable plasticizers are, for example, diesters of phthalic acid, cyclohexanedicarboxylic acid or adipic acid, or tackifying resins. Such resins are as described in EP 1329492, for example, natural resins such as colophony resins or hydrocarbon resins.

Due to the affinity of the absorber to the core material, the absorber is primarily mixed with the core material and / or incorporated into the capsule wall.

A distinction is made between different types of absorbers: - organic IR absorbers - Organic microwave absorber

- Inorganic IR absorbers

- Inorganic microwave absorber

Under IR absorber is meant a compound in the context of this application, which is applied in a layer thickness of 50 microns at at least one wavelength of radiation of the wavelength range of 700 nm to 1 mm, an absorption> 90% shows. Preferably, the wavelength range of> 700 nm to 2000 nm, and the wavelength is 9.6 microns and 10.6 microns.

Under microwave absorber, the microwaves of the wavelength range of> 1 mm is understood to be a connection in the context of this application, absorbs up to 1 m. the technically relevant frequencies of 2.45 GHz, 433- 444 MHz and 902-928 MHz are particularly preferred.

Organic IR absorbers are widely described in the literature. Such compounds include cyanine, metal complexes, quinone, azo dyes, Multiphenyl- methane, perylenes, quaterrylene, aromatic annulenes, and particularly metal tallphthalocyanine, rylimide Metallnaphthalocyanine, metalloporphyrins, terrylimides and quaternization. Compounds having such skeletons are dependent on the substituents soluble in solvents, so dyes, or insoluble and thus pigments. Exemplary IR absorbers can be mentioned as described in WO 02,076,988th Particular preference -Lumogen ® IR 765 and 788 of BASF Aktiengesellschaft.

Organic microwave absorbers are described for example in prior European application 07 106 445.5, which is expressly incorporated by reference.

Inorganic microwave absorbers are metal oxides which have a magnetic moment, as well as carbon black and graphite. In general, the compounds also absorb IR radiation so that the enumeration for both forms of excitation applies.

Suitable inorganic absorbers are particles with an average particle size in the range of 0.1 to 5 .mu.m, which are electrically conductive, magnetic, ferrimagnetic, ferromagnetic table, antiferromagnetic or superparamagnetic. The application of an additional loan static magnetic field leads to a better absorption of these particles (typical field strengths are from 10 to 60 mTesla). By way of example mention may be metals and transition metals, such as Al, Fe, Zn, Ti or Cu, their salts such as their oxides, such as ZnO, iron oxides, especially ferrites, and TiO 2, carbonates, or sulfides, carbon such as graphite, carbon black, nanoparticulate carbon or nanotubes , silicon carbides, Silici- to, alkali and alkaline earth etc. Further, the mixed metal oxides referred to in WO 03/054102 are suitable, which are expressly incorporated by reference. Preference is given to carbon black, and graphite FesCU.

According to one embodiment, microcapsules having a capsule core comprising a polyacrylate copolymer, particularly preferably a UV-crosslinkable polyacrylate copolymer, and at least preferably an organic IR-absorber.

According to another embodiment, microcapsules having a capsule core comprising a polyacrylate copolymer, particularly preferably a UV-crosslinkable polyacrylate and at least one preferably inorganic microwave absorber.

The absorber particles, provided that they are inorganic particles such as carbon black or Fe3Ü4 dispersed in the lipophilic solvent of the capsule core. Provided that the absorber particles are dispersed, they should have a particle size <5 microns, preferably <2 microns.

The microcapsules of the invention contain, depending on the type of the absorber and the activation form, a maximum of 10 wt .-% absorber, preferably from 0.1 to 10 wt .-%, especially 1 to 7 wt .-%, most preferably 2 to 5 wt .-% absorber, based on the total amount of wall polyacrylate copolymer and Polyharnstoffkapsel-.

The capsule wall according to the invention consists essentially of polyurea.

Under isocyanate is in the context of this application, a two or more isocyanate natgruppen bearing with the amine component, namely, a di-, polyamine, di- and / or polyamidine, to understand reacting compound.

Suitable polyisocyanates are aliphatic, cycloaliphatic, araliphatic and aro- matic isocyanates.

Suitable aromatic diisocyanates include, for example 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1, 5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-Dimethyldiphenyl- diisocyanate, 1, 2-diphenylethane diisocyanate, phenylene diisocyanate, and / or tetra- methylxylylendiisocyat.

Aliphatic and cycloaliphatic diisocyanates include, for example tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methyl-pentamethylene 1, 5-diisocyanate, 2-ethylbutylene-1, 4-diisocyanate, 1-isocyanato -3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1, 4- and / or 1, 3-bis (isocyanatomethyl) cyclohexane (HXDI), cyclohexane-1, 4-diisocyanate, 1-methyl-2,4- and / or 2, 6-cyclohexandiisocyanato and / or 4,4'-, 2,4'- and / or 2,2'-dicyclohexylmethane diisocyanate.

Examples of higher functional isocyanates are triisocyanates such. B. triphenylmethane 4,4 ', 4 "-triisocyanate, the cyanurates of the aforementioned diisocyanates, as well as the oligomers obtainable by partial reaction of diisocyanates with water, eg. As the biurets of the aforementioned diisocyanates, further oligomers through specific implementation are available from semiblockierten diisocyanates with polyols which have greater than 2 and preferably 3 or more hydroxyl groups on average.

It is also possible that obtained during industrial isocyanate natgruppen isocyanate-containing distillation residues, optionally dissolved in an o more of the aforementioned polyisocyanates to use. Further, it is possible to use any mixtures of the aforementioned polyisocyanates.

Suitable modified, aliphatic isocyanates are, for. For example, those based on hexamethylene-1, 6-diisocyanate, m-xylylene diisocyanate, 4, 4'-diisocyanate which have isocyanurate anatgruppen at least two per molecule, dicyclohexylmethane diisocyanate and isophorone diisocyanate.

Also suitable z. B. polyisocyanates based on derivatives of hexamethylene len-1, 6-diisocyanate with a biuret structure as described in DE-AS 1,101,394, DE-AS 1,453,543, DE-OS 1,568,017 and DE-OS 1,931,055 ,

Also usable are polyisocyanate polyuretonimines as containing hexamethylene-1, 6-diisocyanate caused by Carbodiimidi- tion of biuret with organophosphorus catalysts, where Carbodii- primarily formed amide groups react with further isocyanate groups to give uretonimine groups.

It can also be used isocyanurate-modified polyisocyanates with more than two terminal isocyanate groups, such. B. those whose preparation on the basis of hexamethylene diisocyanate in DE-OS 2839133 described. Other isocyanurate-modified polyisocyanates can be obtained analogously.

It can also be used mixtures of said isocyanates such. B. mixtures of aliphatic isocyanates, mixtures of aromatic isocyanates, mixtures of aliphatic and aromatic isocyanates, in particular mixtures which optionally comprise modified diphenylmethane diisocyanates.

The di- described herein and / or polyisocyanates can also be used as mixtures with di- and Polycarbonsäurechloriden as sebacoyl chloride, terephthaloyl chloride, adipic acid dichloride, oxalic acid dichloride, Tricarballylsäuretrichlorid and 1, 2, 4,5-benzene carboxylic acid tetrachloride, with di- and Polysulfonsäurechloriden Wiel, 3 - Benzolsulfonsäuredichlorid and 1, 3, 5-Benzolsulfonsäuretrichlorid, phosgene and with dichloro-and Polychlorameisensäureester such as 1, 3, 5-Benzoltrichloroformiat and ethylene lenbischloroformiat apply.

Furthermore, for example, oligo- or polyisocyanates can be used, resulting from said di- or polyisocyanates or mixtures thereof by linking by means of urethane, allophanate, urea, biuret, uretdione, amide, isocyanate, carbodiimide, uretonimine - let which manufacture oxadiazinetrione or iminooxadiazinedione structures.

Preferred isocyanates are biuretisch or isocyanuretisch linked oligomers of hexamethylene diisocyanate, and isophorone diisocyanate, m-

Tetramethylxylylene diisocyanate or oligomers of the methylene diphenyl diisocyanate, and mixtures of these, and above mentioned isocyanates. Especially preferred are isophorone diisocyanate and isocyanuretisch linked oligomers of hexamethylene diisocyanate.

Di- and polyamines of the invention can be substituted with hydroxyl groups. Also suitable are di- and / or polyamidines, particularly those that have an intramolecular azo or peroxo group. These compounds may be used in pure form or as mixtures with one another. The installation of additional azo or peroxo-bearing di- and / or polyamidines leads clauses to microcapsule that release well temperature increase their ingredients.

Suitable amines are generally di- and polyamines of the molecular weight range from 32 to 500 g / mol, which contain at least two amino groups selected from the group of primary or secondary amino groups. Examples thereof are diamines such as diaminoethane, diaminopropanes, diaminobutanes, diaminohexanes, amino 3-aminomethyl-3,5, 5-trimethyl-cyclohexane (isophoronediamine, IPDA), 4, 4'-

Diaminodicyclohexylmethane, 1, 4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylene triamine, 1, 8-diamino-4-aminomethyloctane, hexahydro-2,4,6-trimethyl-1, 3,5-triazines or polyamines such as tetraethylenetriamine, pentaethylenetetramine or polyimines or polyether amines. As amidine which is marketed as a basic solution of WAKO Inc. is exemplified 2,2'-azobis (2-methylpropionamidine) dihydrochloride. Azo or peroxo groups bearing amines are described in EP-AO 516 742. It is also possible the amines in blocked form, for. Example in the form of the corresponding ketimines (see, for. Example, CA-A-1129128), ketazines (. Z see. Eg, US-A 4,269,748) or amine salts (see. US-A 4292226) use. Preferred di- or polyamines include aliphatic C2-C6-diamines such as ethylene diamine, aliphatic C2-C6-triamines such as diethylenetriamine and hexahydro-2,4,6-trimethyl-1, 3,5-triazine. the amidine of 2,2'-azobis is also preferred (2- methylpropionamidine) dihydrochloride in basic solution.

The amount of isocyanate to be used according to the invention and the Aminkomponen- te, namely the di-, polyamine, di- and / or Polyamidins, moves in the usual for interfacial polyaddition frame.

The theoretical amount necessary for wall formation amine component is calculated from the content of reactive isocyanate groups of the isocyanate used and the total mass of aspired polymer shell around the microcapsule core.

For the reaction of all the in-the oil phase NCO groups equal number of amino groups are at least the- oretisch required. It is therefore advantageous nat the isocyanate and to use the amine component in proportion to their equivalent weights. However, it is also possible to deviate from the stoichiometrically calculated amount of amine either downward because not be ruled out a side reaction of the isocyanate with the existing excess water is close at interfacial polyaddition, or to use an excess of the amine component, because such is not critical.

In particular, therefore it applies the amine component in an amount that is between 50 and 150 wt .-% of the theoretical calculated. This amount is preferably between 100 and 130 wt .-%, based on the theoretically calculated amount.

The present invention further relates to a process for the preparation of microcapsule clauses, comprising the steps of

a) preparing a lipophilic mixture comprising a polyacrylate copolymer and at least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, one or more isocyanates, and optionally solvent, b) emulsifying the mixture obtained from a) in a hydrophilic solvent, and c) formation of the capsule wall by adding the solution obtained from b) emulsion with a di- and / or polyamine and / or di- and / or polyamidine.

and the microcapsule dispersion obtained according to this method. The present invention further relates to a second alternative method for preparing microcapsules comprising the steps of

a) preparing a lipophilic mixture comprising a polyacrylate copolymer and at least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, and optionally solvent, b) emulsifying the mixture obtained from a) in a hydrophilic solvent, c) addition of a or more isocyanates to the emulsion from b), d) emulsifying the mixture and e) obtained from c) formation of the capsule wall by displacing the emulsion obtained from d) with a di- and / or polyamine and / or di- and / or polyamidine ,

and the microcapsule dispersion obtained according to this method.

The optional solvent is a non-hydrophilic solvent. It is preferable that one of the lipophilic solvent described above, which is optionally present.

To obtain a stable emulsion, you need surfactants such as polymeric protective colloids usually. As a rule, used surface-active substances which mix with the hydrophilic phase.

In general, the microcapsules are made of at least one organic protective colloid in the presence of. These protective colloids may be ionic or neutral. Protective colloids can be used both individually and in mixtures of several of the same or different charged protective colloids.

organic neutral protective colloids are preferably used. Organic protective colloids are preferably water-soluble polymers which ensure the formation of closed capsule walls, and microcapsules having particle sizes in the preferred range of 0.5 to 50 microns, preferably 0.5 to 30 microns preferably 0.5 to 10 .mu.m form.

Organic neutral protective colloids are, for example, cellulose derivatives such as hydroxyethylcellulose, methylhydroxyethylcellulose, methylcellulose, and carboxymethylcellulose, polyvinylpyrrolidone, copolymers of vinylpyrrolidone, gelatin, Gummiarabi- cum, xanthan gum, casein, polyethylene glycols, polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropylcellulose. Preferred organic neutral protective colloids are polyvinyl alcohol and partially hydrolyzed polyvinyl acetates and methylhydroxypropylcellulose preferably in combination. Polyvinyl alcohol is obtainable by polymerizing vinyl acetate, optionally in the presence of comonomers, and hydrolysis of the polyvinyl acetate with the elimination of the acetyl groups to form hydroxyl groups. The degree of hydrolysis of polymethyl ren may for example be 1 to 100%, and is preferably in the range of 50 to 100%, in particular from 65 to 95%. Partially hydrolyzed polyvinyl acetates a degree of hydrolysis of <50% and polyvinyl alcohol of> 50 to 100% is to be understood in the context of this application. The production of homo- and copolymerization of vinyl acetate th as well as the hydrolysis of these polymers to form Vinylal- koholeinheiten containing polymers is generally known. Vinyl alcohol units-containing polymers are sold, for example as Mowiol ® brands from Kuraray Specialties Europe (KSE).

Preferred are polyvinyl alcohols or partially hydrolyzed polyvinyl acetates whose Vis viscosity by a 4 wt .-% aqueous solution at 20 0 C has a value in the range from 3 to 56 mPa * s DIN 53015, preferably a value of 14 to 45 mPa * s , in particular 22 to 41 mPa * s. Polyvinyl alcohols preferably having a degree of hydrolysis of> 65%, preferably> 70%, in particular> 75%.

Also advantageous are hydroxypropyl as sold as Culminal.RTM ® brands from Hercules GmbH, Dusseldorf. Hydroxypropyl celluloses are preferred having a viscosity of 2 wt .-% solution at 20 0 C 25-16000 mPas, preferably 40-600, particularly preferably 90-125 mPas (Brookfield viscosity RVT).

In general, polyvinyl alcohol or polyvinyl acetate or mixtures of these teilhydrolysiert.es used with Hydroxylpropylcellulosen in a total amount of at least 3 wt .-%, preferably from 3.5 to 8 wt .-%, based on the Mic rokapseln (without protective colloid). It is possible to add further protective colloids in addition to the above-mentioned preferred amounts of polyvinyl alcohol or polyvinyl acetate or teilhydrolysier- tem add hydroxypropyl cellulose. the microcapsules are preferably, without the addition of further protective colloids prepared with only polyvinyl alcohol and / or partially hydrolyzed polyvinyl acetate and / or hydroxypropyl cellulose.

Further, it is possible to costabilization surfactants, preferably add nonionic surfactants. Suitable surfactants can be found in the Ηandbook of Industrial Surfactants ", the contents of which express reference is made. The surfactants can be used in an amount of 0.01 to 10 wt .-% based on the water phase of the emulsion.

Using the surfactant, it creates a stable emulsion with stirring. According to a preferred variant, the amine component is added only to the stable emulsion of the solution of polyacrylate copolymer, absorber and isocyanate or during the emulsifying step. As a rule, so that the interface polyaddition or-condensation and thus the wall formation starts.

According to a likewise preferred variant, the isocyanate is added only to the stable emulsion of the solution of polyacrylate copolymer and absorber in water or already during the emulsifying step. The stable emulsion or during the emulsifying step thus produced is not added until the amine component. As a rule, so that the interface polyaddition or-condensation and thus the wall formation starts.

The interface reaction can proceed, for example, at temperatures in the range from -3 to +98 0 C, preferably carried out at 10 to 80 0 C.

The dispersion of the core material is depending on the size of the capsules to be prepared in a known manner. For the preparation of large capsules, dispersion using effective stirrers extends below, of particular propeller or Impellerrührern. Small capsules, particularly if the size is to be below 50 microns, require homogenizing or dispersing, these devices can be provided with or without forced-flow means.

The homogenization can be carried further by the application of ultrasound (z. B. Branson Sonifier Il 450). the devices described in GB 2250930 and US 5,108, 654 for example, are suitable for the homogenization by means of ultrasound.

The capsule size can be large weight over the number of revolutions of the dispersing / homogenizer and / or by means of the concentration of the protective colloid or over its molecu-, that is, within certain over the viscosity of the aqueous continuous phase boundaries can be controlled. In this case decreases with increase in the number of revolutions up to a limit number of revolutions, the size of the dispersed particles.

It is important that the dispersing devices are angewen- det at the start of capsule formation. In continuously operating devices with forced flow, it is advantageous to pass the emulsion several times by the shear field.

The preparation of the emulsion is carried out for the dispersion of high-viscosity media thermally stable in a temperature range from 30 to 130 0 C, preferably 40 to 100 0 C.

According to the inventive method microcapsule dispersions can be prepared of microcapsules with a content of 5 to 50 wt .-%. The microcapsules are individual capsules. By suitable conditions during dispersion capsules can be up to 80 microns and made larger with an average particle size in the range of 0.5. Capsules are preferred having a mean particle size of 0.5 to 50 microns, preferably up to 30 microns.

When the average particle diameter is the weight average particle diameter determined by quasi-elastic dynamic light scattering. Especially advantageous is the very narrow size distribution of the capsules.

The microcapsules of the invention can preferably be processed directly as aqueous dispersion. A spray drying to a microcapsule powder is generally possible, but has to be made carefully.

The microcapsules of the invention can be processed well and have good tightness on. An increase in temperature usually at temperatures ranging from 100 to 180 0 C, they are permeable to their ingredients. This allows a controlled release of ingredients that can be formulated directly in the form of microcapsules thus not have to be added just before use cumbersome.

The microcapsules of the invention are useful as pressure sensitive adhesives, for example for the construction of block-resistant coatings on paper, cardboard, wood, etc., wherein this radiation-induced from the capsule contents can be released. They are particularly suitable for the production of coatings, for example on labels, adhesive tapes and films. The labels may be, for example, made of paper or plastics such as polyesters, polyolefins or PVC. The adhesive tapes or films may also be made of the above plastics.

The application of the microcapsules is carried out as a dispersion medium in a hydrophilic solvent, preferably as an aqueous dispersion. This can optionally further effect substances such. B. slip additives, adhesion promoters, leveling agents, film forming auxiliaries, flame retardants, corrosion inhibitors, waxes, siccatives, matting agents, deaerating agents, thickeners, and biocides can be added.

According to a preferred embodiment, it is possible to add further abovementioned IR or microwave absorber to increase the absorption of the microcapsule dispersion. It may be both involve the concrete used in the encapsulation absorber and a dissimilar. These absorbers are in contrast to the absorbers encapsulated in the continuous phase before freely dispersed. The present invention therefore also provides a method for bonding at least two substrates which comprises applying to the surface of at least one substrate microcapsules comprising a capsule wall of polyurea and a capsule core comprising a polyacrylate copolymer and at least one compound which electromagnetic radiation from the wavelength range of> 700 nm to 1 m absorbed, may be applied before, during or irradiated by a joining of the substrates with radiation in the wavelength range of the absorption of the absorber, wherein in the case of irradiation by the joining of the substrates at least one of the substrates for the radiation at least partially permeable have to be.

To produce the coatings, the microcapsule dispersions can be applied to the substrates to be coated, ie, the solvent is subsequently removed by suitable methods. It is possible according to the invention applying a non-tacky surface or selectively microcapsule dispersion and release through specific irradiation single area the adhesive only at these locations.

The introduction of energy and thus release of adhesives, electromagnetic alternating fields are suitable. Which can be produced, for example, with lamps which emit a high amount of IR radiation, infrared lasers, microwave generators or such as klystrons or magnetrons.

Suitable lasers are listed as examples:

- Gas lasers such as CO 2 laser (wavelength 9.6 microns and 10.6 microns), helium-neon

Laser (HeNe laser, wavelength 632.8 nm) and krypton ion laser (647.1 nm strongest line; 676.4 nm; 752.5 nm; 799.3 nm); Dye lasers solid-state lasers such as Nd: YAG laser (1064 nm), Nd: (tunable from 670 to 1100 nm) doped sapphire laser and fiber laser (Erbium, ytterbium, neodymium or 0.7 microns: glass laser (1061 nm), Ti tan to 3 microns) and semiconductor lasers (700 nm to 4 microns).

The wavelengths of the IR radiation used is preferably in a range of> 700 nm to 2000 nm. Suitable wavelengths are 9.6 microns and 10.6 microns. Is preferred for NIR / IR irradiation, a line density of 1-100 W / cm 2 is preferably 1-40 W / cm 2, an irradiation time of 0.01-20 s.

The frequency of the microwave radiation used is preferably in a loading range from 500 MHz to 25 GHz. Thus, for example, electro-magnetic radiations of the so-called ISM (Industrial Scientific and Medical Application) use, where the frequencies between 100 MHz and 200 GHz. Details of alternating electromagnetic fields in the microwave range are described in Kirk Othmer, "Encyclopedia of Chemical technology", 2nd Edition, Volume 15, Chapter "Micro-wave technology", to which reference is hereby made.

Preferred layer thicknesses for both IR as well as the microwave irradiation are, for example 1 to 500 .mu.m, more preferably 5 to 300, most preferably from 10 to 100 microns. Thicker layers are possible, but usually take in their depth of radiation permeability from.

Unless it is in the polyacrylate copolymer is a crosslinkable with UV light polyacrylate copolymer, the coating can be irradiated even additionally irradiated with high-energy radiation, preferably UV light, so that a crosslinking takes place. This can occur before, simultaneously or preferably subsequently happened to the release of the Polyacrylatcopolymers from the capsules. In general, the loading-coated substrates are to placed on a conveyor belt and guided past the conveyor belt past a radiation source, eg a UV lamp. The degree of crosslinking of the polymers depends on the duration and intensity of exposure. The UV radiation dose is preferably in total from 2 to 1500 mJ / cm 2 irradiated area.

The coated substrates obtained can be used preferably as self-adhesive products such as labels, adhesive tapes or protective films.

The obtained melt adhesive coatings have good performance characteristics, such as good adhesion and high internal strength, even during long periods of storage of the microcapsule dispersions of the invention.

Examples

Example 1 (a model system with dye in order to demonstrate the capsule wall opening by means of IR radiation)

In a 2 l vessel having a dispenser (diameter 5 cm) was the following mixture of water phase

467.8 g of deionized water (DI = demineralized water)

35 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol ® 15 /

79 Kuraray Europe GmbH, viscosity of a 4 wt .-% solution at 20 0 C, of 15 mPa.s according to DIN 53015 and a saponification degree of 79%) 140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung

(Culminal.RTM ® MHPC 100, Hercules GmbH)

and oil phase

17.85 g Isocyanuratisiertes hexamethylene diisocyanate (Basonat HI 100 ®, the

BASF Aktiengesellschaft)

314.13 g of diisopropylnaphthalene

0.94 g Pergascript Red I 6 B ® (Ciba Specialty Chemicals) 0.03 g Lumogen ® IR 788 (BASF Aktiengesellschaft)

prepares.

The mixture was dispersed for 15 minutes at room temperature at a speed of 5000 rpm and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle. Within 30 minutes, 17.08 g of a 20 wt .-% aqueous solution of hexahydro-2,4,6-trimethyl-1, 3,5-triazines were fed. Then the reaction mixture following temperature program was subjected: heating to 60 0 C in 30 minutes, holding the temperature for 60 minutes followed by cooling to room temperature.

The solids content of this dispersion was 27.6%, with a mean particle size of 12.02 microns (determined by light scattering).

Example 2 (without IR absorber - not of the invention)

In a 2 l vessel having a dispenser (diameter 5 cm) was the following mixture of water phase

467.8 g of demineralized water

35 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol

15/79)

140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung

(Culminal MHPC 100)

and oil phase

17.85 g Isocyanuratisiertes hexamethylene diisocyanate (Basonat HI 100)

314,13g Diisopropylnaththalin

0.94 g Pergascript Red I 6 B

prepares. The mixture was dispersed for 15 minutes at room temperature at a speed of 5000 rpm and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle. Within 30 minutes, 17.08 g of a 20 wt .-% aqueous solution of hexahydro-2,4,6-trimethyl-1, 3,5-triazines were fed. Then the reaction mixture following temperature program was subjected: heating to 60 0 C in 30 minutes, holding the temperature for 60 minutes followed by cooling to room temperature.

The solids content of this dispersion was 25.5%, with an average particle size of 7.19 microns (by light scattering determined).

EXAMPLE 3 The procedure of Example 1 with the difference that the aqueous solution of instead of the 20% strength by weight aqueous hexahydro-2,4,6-trimethyl-1, 3,5-triazine 73.3 g of a 7.5% solution of diethylenetriamine was added.

The solids content of the dispersion thereafter obtained was 33.5%, with a medium- sized particle size of 8.89 microns (by light scattering determined).

Examples 1-3

The microcapsule dispersions obtained according to Examples 1-3 were each applied to a silica gel coated glass plate using a doctor blade, said homogeneous films were obtained after drying. To destroy the capsule wall, the latter were then coated with a titanium / sapphire laser (wavelength: 773 nm; power density: 20 W / cm 2) was irradiated.

The release of the capsule contents, which is proof of the destruction of the capsule wall is indicated by the leuco base Pergascript Red I 6B, which is protonated by the acid kagel SiIi- and thereby assumes a red color.

The results of this irradiation experiment are summarized in Table 1 below. The coloration of the silica gel plate was visually evaluated

0: no staining 1: light red color

2: Strong red color.

The intensity of the color of the irradiation Io and after n seconds irradiation I is given n.

Table 1

Figure imgf000024_0001

Example A: Preparation of Polyacrylatcopolymers

A polymerization apparatus consisting of glass reactor feed vessels, reflux condenser, stirrer and nitrogen inlet, 283g metal were submitted ethyl ketone (MEK) in a light stream of nitrogen and heated to 80 0 C. There were 61 consisting methacrylate 1 1 g of a monomer mixture of 90 wt .-% of 2-ethylhexyl acrylate, 9 wt .-% methyl and 1 wt .-% acrylic acid 4- (4-benzoylphenoxycarbonyloxy) butyl ester (photo-initiator) were added. After again reaching 80 0 C. 3.23 g of an initiator solution of 8 g of tert-butyl perpivalate and 56.7 g MEK were added and 10 min merized anpoly-. Then, 1 161, 2 min g monomer mixture in 3 hours and 61, 45 g of initiator solution over 3 h 15 °. fed in. Then a solution of 3.20 g of tert-butyl perpivalate in 37.25 g of MEK in 5 min was added and the temperature was raised to 85 ° C and polymerized for 45 min. Then 0.36 g of 2,6-di-tert. Butyl-p-cresol were added. Then, the solvent was distilled off in vacuum, the temperature thereby slowly raised to 135 ° C and a further 1 h in vacuo at 135 ° C degassed.

Solid content: 99.9% K-value: 46 zero-shear viscosity at 110 0 C: 25 Pas.

The polymer can be redissolved in other solvents.

example 4

In a 2 l vessel having a dispenser (diameter 5 cm) was the following mixture of water phase

440.65 g of demineralized water 70 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol

15/79)

140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung

(Culminal MHPC 100)

and oil phase

95.27 g heptane 218.75 g of a 80 wt .-% solution of a polyacrylate of Example A in

isooctane

0.04 g Lumogen IR 788 18.1 g Isocyanuratisiertes hexamethylene diisocyanate (Basonat HI 100), 10.54 g isophorone diisocyanate

prepares.

The mixture was dispersed for 15 minutes at room temperature at a speed of 6000 rpm and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle. Within 30 minutes, 3.5%-triazines were fed 76,37g of a 9 wt .- aqueous solution of hexahydro-2,4,6-trimethyl-1. Then the reaction mixture following temperature program was subjected: heating to 60 0 C in 30 minutes, holding the temperature for 2 hours followed by cooling to room temperature.

The solids content of the dispersion obtained hereinafter was 25%, with an average particle size of 14.19 microns (determined by light scattering).

Example 5 Water phase 440.65 g of demineralized water 70 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol 15/79)

140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung (Culminal MHPC 100) 1, 0 g defoamer based on an organic silicone-free, silica-containing polymer (TEGO ® Foamex 830)

oil phase

95.31 g heptane

201, 25 g of a 80 wt .-% solution of the polyacrylate of Example A in o

Xylene, 0.55 g of carbon black (Printex ® 300, Degussa)

adding 1

17.68 g Isocyanuratisiertes hexamethylene diisocyanate (Basonat HI 100)

10.29 g isophorone

The mixture of water and oil phase was heated to 60 0 C, dispersed for 40 minutes at a speed of 6000 rpm in a laboratory dissolver, then cooled to a temperature below 20 0 C, supplied to Addition 1, further 10 minutes at a speed of 600 rpm dispersed, and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle.

Heating to 60 0 C in 30 minutes, holding the temperature for 2 hours followed by cooling to room temperature: within 30 minutes (were 77,07g a wt .-% aqueous solution of diethylenetriamine supplied Then the reaction mixture following temperature program was subjected to..

The solids content of this dispersion was 28.8%, with a mean particle size of 10.74 microns (as determined light scattering).

example 6

Water phase 447.61 g of demineralized water 70 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol 15/79)

140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung (Culminal MHPC 100)

1.0 g of defoamer based on an organic silicone-free, silica-containing polymer (TEGO Foamex 830)

Oil phase 301.14 g of a 80 wt .-% solution of a polyacrylate of Example A in the o

xylene

0.84 g of carbon black (Degussa Printex 40)

Adding 1 17.68 g lsocyanuratisiert.es hexamethylene diisocyanate (Basonat HI 100), 10.29 g isophorone diisocyanate

The mixture of water and oil phase was heated to 60 0 C, dispersed for 40 minutes at a speed of 6000 rpm in a laboratory dissolver, then cooled to a temperature below 20 0 C, supplied to Addition 1, further 10 minutes at a speed of 600 rpm dispersed, and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle. % Within 30 minutes were fed aqueous solution of diethylenetriamine 77,07g of a 9 wt .-. Then the reaction mixture following temperature program was subjected: heating to 60 0 C in 30 minutes, holding the temperature for 2 hours followed by cooling to room temperature. The solids content of this dispersion was 34.7%, with an average particle size of 31 55 microns (by light scattering determined).

Example 7 Water phase 380 g demineralized water 70 g of a 10 wt .-% aqueous polyvinyl alcohol (Mowiol 15/79)

140 g of a 5 wt .-% aqueous Methylhydroxypropylcelluloselösung (Culminal MHPC 100)

1, 0 g defoamer based on an organic silicone-free, silica-containing polymer (TEGO Foamex 830)

oil phase

218.7 g of a 80% solution of a polyacrylate of Example A in o-xylene, 104 g of heptane, 0.04 g of Lumogen IR 788

Adding 1 9 g Isocyanuratisiertes hexamethylene diisocyanate (Basonat HI 100)

5.25 g isophoronediisocyanate

Addition of 2 9.6 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (WAKO V 50)

5 g of a 50% solution of sodium hydroxide in water 70 g of demineralized water

The mixture of water and oil phase was heated to 75 0 C, dispersed for 40 minutes at a speed of 6000 rpm in a Labordissolverrührer, then cooled to a temperature below 20 0 C, supplied to Addition 1, further 10 minutes at a speed of 600 rpm dispersed, and then transferred to a flask equipped with an anchor stirrer, 2 liter kettle.

Within 30 minutes the addition was fed to 2, and then within 30 minutes 72.4 g of a 3.3 wt .-% aqueous solution of diethylenetriamine. Then the reaction mixture following temperature program was subjected: heating to 60 0 C in 30 minutes, holding the temperature for 2 hours followed by cooling to room temperature.

The solids content of this dispersion was 20.7%, with an average particle size of 4 microns (determined by light scattering). Examples 8 - 1 1

To improve the radiation absorption of the microcapsule dispersions of Examples 4 and 6 was further added an aqueous dispersion of carbon black (Black Lepton® ®, BASF AG).

Figure imgf000028_0001

Examples 4-11 a) and (b) activation by NIR laser and microwave) The microcapsule dispersions obtained according to Examples 4-11 were each applied with a squeegee on a glass substrate. After drying got MAN homogeneous films. The homogeneous films were resistant to blocking, not sticky.

a) release by IR radiation to destroy the capsule wall were then this with a titanium / sapphire laser (wavelength: 773 nm; power density: irradiated 20 W / cm 2). In a series of experimental five points on the plate were irradiated different lengths. It was then assessed visually and to the touch, was released from soft irradiation time of the adhesive. The irradiated point shone light and felt sticky. The following table sets out the respective minimum irradiation times.

The results of this irradiation experiment are summarized in Table 2:

Table 2 .: released minimum irradiation time until the adhesive

Figure imgf000028_0002
Figure imgf000029_0001
b) release by microwave irradiation

To release the contents by means of microwave radiation 10 cm (300 watts, 7 I volume power) irradiates two pieces of the coated glass loading in a microwave.

The results are summarized in Table 3 below.

Table 3: Minimum irradiation time until the adhesive was released.

Figure imgf000029_0002

Claims

claims
1. Microcapsules comprising a capsule wall of polyurea and a capsule core comprising a polyacrylate copolymer and at least one compound which electromagnetic radiation from the wavelength range of 700 nm to
1 m absorbed.
2. Microcapsules according to claim 1, characterized in that the polyacrylate is a copolymer comprising at least 40 wt .-% of Ci - C10 alkyl acrylates is constructed and / or methacrylates.
3. Microcapsules according to claim 1 or 2, characterized in that the polyacrylate copolymer 0.0001 to 1 mol of a photoinitiator or a photoinitiator effective as bonded to the polymer molecule group contains per 100 g of polyacrylate copolymer.
4. Microcapsules according to one of claims 1 to 3, characterized in that the glass transition temperature (T 9) is of -60 to +10 0 C Polyacrylatcopolymers.
5. Microcapsules according to one of claims 1 to 4, characterized in that the compound which electromagnetic radiation from the wavelength range of 700 nm absorbed by 1 m, is an organic IR-absorber.
6. Microcapsules according to one of claims 1 to 4, characterized in that the compound which electromagnetic radiation from the wavelength range of 700 nm absorbed by 1 m, is an inorganic absorber.
7. Microcapsules according to one of claims 1 to 6, characterized in that the capsule wall consists of a di- and / or polyamine and / or di- and / or
Polyamidine and an isocyanate chosen from biuretisch or isocyanure- table linked oligomers of hexamethylene diisocyanate, isophorone diisocyanate, m-Tetramethylxylylenediisocyanat or oligomers of these isocyanates or isocyanate Methylendiphenyldiisocy- Anat is built up with other isocyanates.
8. Microcapsules according to one of claims 1 to 7, characterized in that the capsule wall of a isocyanate and a di- or polyamine selected from aliphatic C2-C6-diamines, aliphatic C2-C6 triamines and hexa- hydro-2,4, 6-trimethyl-1, 3,5-triazine, is established.
9. A process for the preparation of microcapsules according to claims 1 to 8, comprising the steps of
a) preparing a lipophilic mixture comprising a polyacrylate copolymer and at least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, one or more isocyanates, and optionally solvents b) emulsifying the solution obtained from a) mixing in a hydrophilic solvent and c ) form the capsule wall by adding the solution obtained from b) emulsion with a di- and / or polyamine and / or di- and / or polyamidine.
10. A process for the preparation of microcapsules according to claims 1 to 8, comprising the steps of
a) preparing a lipophilic mixture comprising a polyacrylate copolymer and at least one compound that absorbs electromagnetic radiation in the wavelength range of 700 nm to 1 m, and optionally solvent, b) emulsifying the mixture obtained from a) in a hydrophilic solvent, c) addition of a or more isocyanates to the emulsion from b), d) emulsifying the mixture and e) obtained from c) formation of the capsule wall by displacing the emulsion obtained from d) with a di- and / or polyamine and / or di- and / or polyamidine ,
1 1. microcapsule dispersion obtained by the process according to claim 8 or. 9
12. A microcapsule dispersion comprising microcapsules according to claim 1 dispersed in a hydrophilic solvent.
13 according to claim 12 additionally comprising dispersed microcapsule dispersion a compound that electromagnetic radiation from the wavelength range 700 nm to 1 m absorbed in the continuous phase.
14. Use of microcapsules comprising a capsule wall of polyurea and a capsule core comprising a polyacrylate copolymer and at least one compound which electromagnetic radiation from the wavelength range 700 nm to 1 m absorbed as pressure sensitive adhesives.
15. A method for bonding at least two substrates, in which the O- berfläche at least one substrate microcapsules comprising a capsule wall of polyurea and a capsule core comprising a Polyacrylatcopo- lymer and at least one compound which electromagnetic radiation from the wavelength range 700 nm to 1 m absorbed, may be applied before, during or irradiated by a joining of the substrates with radiation in the wavelength range of the absorption of the absorber, wherein in the case of irradiation by the joining of the substrates at least one of the substrates for the radiation must be partially transparent at least ,
16. Use of microcapsules comprising a capsule wall of polyurea and a capsule core comprising a polyacrylate copolymer and at least one compound which electromagnetic radiation from the wavelength range 700 nm to 1 m to the absorbed radiation-induced release of adhesives.
PCT/EP2008/066494 2007-12-05 2008-12-01 Microcapsules having radiation-induced release WO2009071499A1 (en)

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