MXPA98009884A - Adhesive microspheres sensitive to compound pressure - Google Patents

Abstract

Compound pressure-sensitive adhesive microspheres comprising two or more water-insoluble polymers that are completely mixed within the boundaries of polymeric microspheres are provided. The range of monomers and polymers are chosen to design the properties of the pressure sensitive adhesive microsphere composition for specific performance and / or application requirements. Any polymer that can be dissolved in a monomer solvent or mixture of monomeric solvents can be used to prepare the composition of pressure sensitive adhesive microspheres. The pressure-sensitive adhesive microspheres according to the invention can be prepared using suspension polymerization via free radicals.

Description

COMPOSITE PRESSURE SENSITIVE ADHESIVE MICROSPHERES Field of the Invention This invention relates to pressure sensitive adhesive polymeric irticrospheres which are comprised of a mixture of two or more polymers within the discrete limits of the polymeric microspheres.

BACKGROUND OF THE INVENTION Inherently sticky pressure sensitive adhesive icospheres are known in the art to be useful in repositionable pressure sensitive adhesive applications and there are numerous differences that discuss the preparation and / or use of polymeric microspheres as elastomeric, inherently sticky . The pressure-sensitive adhesive microspheres can be solid or hollow and generally crosslinked and bonded to a degree such that the particulate nature of the adhesive is maintained throughout the processing and use. Typically, pressure sensitive adhesive microspheres are prepared via suspension polymerization of one or more polymerizable monomers via free radicals in the presence of two reagents and / or suspension stabilizers. The choice of the surfactants and / or suspension stabilizers and their specific combinations with specific monomers can REF: 28837 determine the stability of the suspension, the morphology of the desired particle, the performance characteristics and the like. One method that has been used to prepare materials with improved properties is the synthesis of polymeric materials comprised of mixtures of two or more different polymers. For example, high impact polystyrene (HIPS) is an example of a material that is comprised of a mixture of two or more polymers and that has improved or gives unique properties. HIPS is prepared by dissolving rubbers such as natural rubber or poly (butadiene) in styrene followed by block polymerization, suspension or solution via free radicals. A composite material is obtained, which has impact resistance in relation to virgin poly (styrene). An illustrative example in the field of pressure sensitive adhesives, is that described in EPO 352901 A, wherein the addition of rubbers such as styrene-butadiene block copolymers to pressure-sensitive adhesives based on poly ( acrylate) results in better performance at cold temperature. Another illustrative example in the field of polymerization and emulsion is that described in U.S. Patent No. 4,616,957 in which the developed polymers were dissolved in monomers prior to polymerization.

Yet another example is that described in U.S. Patent No. 5,266,402, wherein the pressure sensitive adhesive comprises an acrylate and acrylate microsphere matrix, wherein each microsphere has a discrete boundary and the microspheres and matrix form a network interpenetrating within the boundaries of the microspheres, where the matrix extends beyond the boundaries of the microspheres.

Brief Description of the Invention Briefly, in one aspect of the present invention, composite pressure sensitive adhesive microspheres are provided comprising two or more water insoluble polymers, which are mixed within the limits of polymeric microspheres. In addition, the present invention advantageously provides unique pressure sensitive adhesive microsphere compositions, as well as unique chemical and physical properties that are derived from blends of polymers that reside fully within the boundaries of polymeric microspheres. The range of monomers and polymers that can be used in this invention can be designed to design the properties of composite pressure sensitive adhesive microspheres for specific performance and / or application requirements. Additionally, the present invention provides repositionable adhesives with improved adhesive properties, such as resistance to cohesiveness, adhesion and static cutting, which can be used in applications such products or removable and repositionable labels, tapes and signs. The pressure-sensitive adhesive microspheres according to this invention can be prepared using the free-radical suspension polymerization. As used in this application, a polymer that is dissolved in a "solvent monomer" before carrying out the suspension polymerization will hereinafter be referred to as a "soluble polymer". A "solvent monomer" is essentially insoluble in water and can be a mixture comprised of one or more monomers and will dissolve the solute polymer. In addition, a solvent monomer may additionally include one or more monomers that can not dissolve a solute polymer, if such a monomer were the only monomer used. Still further, a solvent monomer may include one or more monomers that do not need to be essentially insoluble in water, so long as a mixture of monomers is selected and the mixture is essentially insoluble in water. A "solvent monomer" is polymerized to form a "matrix polymer". The product of the suspension polymerization is a mixture of one or more polymeric solutes and one or more matrix polymers. The monomeric solvents and polymeric sols used to make the pressure-sensitive adhesive microspheres of this invention can be freely selected from a wide range of polymers and monomers. As used in this application, "monomer" can be used to include a mixture of monomers and "polymer" can be used to include a mixture of polymers, as well as copolymers, terpolymers and the like. A solute polymer useful in the practice of the present invention is a polymer that can be dissolved in a solvent monomer. Advantageously, any polymer that can be dissolved in a solvent monomer or mixtures of solvent monomers, as described below, can be used to prepare the composite microspheres of the present invention. Only, the present invention provides composite microspheres, wherein the solute polymer is prepared from (1) monomers that are insoluble in water or do not react in water, (2) the combination of water-soluble or water-reactive monomers and insoluble in water and which do not react in water, with the proviso that the solute polymer is essentially insoluble in water (3) monomers that are not polymerizable via polymerization via free radicals. In addition, the present invention provides composite microspheres, wherein the solute polymer and the matrix polymer are prepared using the same monomer, but the resulting polymers, solute and matrix, respectively, have different molecular weights or crosslink densities, such as, for example, , a composite microsphere comprised of a high molecular weight poly (isooctyl acrylate) and a low molecular weight poly (isooctyl acrylate). A further combination of a composite microsphere comprised of a high Tg polymer, and a low Tg polymer can be provided. - In addition, a portion of the solute polymer can react with the matrix polymer. Additionally, the mixture of solute polymer and matrix polymer can include grafting or crosslinking between various components. Examples of such polymers include, but are not limited to, polymers prepared by polymerization methods that are incompatible with water, such as certain Ziegler-Natta polymerizations, anionic polymerizations, group transfer polymerizations, ring-opening polymerizations, polymerizations. by condensation and polymerization by gradual growth or the like. In addition, the products of the reaction of the monomers substantially water soluble or reactive in water, in combination with sufficient water-insoluble monomers to produce the water-insoluble solute polymer, can be incorporated into the microsphere. Other such solute polymers that can be used include poly (acrylates), poly (methacrylates), poly (styrenes), elastomers such as rubbers (natural and / or synthetic) or styrene-butadiene block copolymers, polyurethanes, polyureas, polyesters, crystalline and non-crystalline polymers, such as poly-α-olefins crystalline and non-crystalline, mixtures thereof and the like. The solute polymers may have a high molecular weight or a low molecular weight or the composite microsphere may be comprised of a mixture of polymers of different molecular weights. The predominant solvent monomers are essentially insoluble in water, and can be comprised of one or more monomers. If a mixture of monomers is used, each of the components does not need to be essentially insoluble in water. Monomers may be used, which may be soluble or insoluble in water, provided that sufficient solvent monomers exist to dissolve the solute polymer. Particularly useful solvent monomers include the (meth) acrylates and vinyl ethers. Other vinyl monomers may be used, such as styrene, acrylonitrile, mixtures thereof and the like, as well as various combinations of such solvent monomers. The combination of at least one solute polymer and at least one solvent monomer is chosen so that the solute polymer can be dissolved in the solvent monomer. The combination of solvent monomer and solute polymer results in an inherently adhesive pressure-sensitive composite polymer microsphere. The mixture of solute polymer and matrix polymer can have a wide range of morphologies, which depend on the compatibility of two or more polymers in the microsphere. Such morphologies include homogeneous mixtures of polymers and phase-separated compositions, in which the different polymers or polymer blends exist in their own phases. The final morphology of the microspheres can be solid or hollow (contains one or more voids). The suspension polymerization of polymer solutions dissolved in monomers offers several distinct advantages over the previously known pressure sensitive adhesive microspheres. An advantage of this invention is the incorporation of polymers in pressure sensitive adhesive microspheres, which may not be prepared by polymerization via free radicals or in the presence of water. Yet another advantage of this invention is the incorporation of reactive portions in water which normally react in the aqueous phase before carrying out the suspension polymerization in the pressure sensitive adhesive microspheres. A further advantage of this invention is the ability to modify the physical properties of the microsphere by incorporating a wide range of solute polymers such as rubber, which can alter the viscoelastic / metallic properties of the microspheres.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Pressure-sensitive adhesive microspheres comprising two or more water-insoluble polymers that are mixed within the boundaries of polymeric microspheres are provided. In addition, the present invention provides pressure sensitive adhesive microsphere compositions having chemical and physical properties that are derived from polymer blends that reside within the boundaries of polymeric microspheres. The composite pressure sensitive adhesive spheres are comprised of a mixture of two or more solute polymers and a matrix polymer, wherein the matrix polymer is the product of the reaction of a solvent monomer. In a different manner, the composite pressure-sensitive adhesive microspheres are comprised of a solute component, comprising at least one solute polymer and a solvent component, comprising a matrix polymer ie the product of the polymerization of at least one solvent monomer. The range of monomers and polymers that can be used in this invention is extensive and can be chosen to design the properties of pressure sensitive adhesive microspheres for specific performance and / or application requirements. Additionally, the present invention can be designed to provide repositionable adhesives with improved adhesive properties such as cohesive strength, adhesion and static cutting and such adhesives can be used in product applications, such as removable and repositionable labels, tapes and signs. The pressure-sensitive adhesive microspheres according to this invention can be prepared by suspension polymerization of monomer solutions and essentially water-insoluble polymers. Specifically, a polymer ('solute component') is dissolved in at least one monomer ('solvent component'). This mixture is then emulsified in an aqueous solution of surfactants and / or suspension stabilizers and polymerized by suspension polymerization.

Solute Component A solute polymer, which is essentially insoluble in water, can be comprised of any monomer or monomer mixture that after polymerization produces a polymer that can be dissolved in a solvent monomer or solvent monomer mixture, as described later. Typically, the solute polymers have a molecular weight (M ") of at least 2000.

The solute component is comprised of several kinds of polymers. Any polymers can be used as long as this solute polymer can be dissolved in a solvent monomer. For example, the solute polymer can be branched, modified, prepared using water-reactive or water-soluble monomers, monomers that are not polymerizable by free radicals, and combinations thereof. In addition, the solute polymers can be prepared according to any polymerization method that can be known to those skilled in the art and can be found generally in various references such as "Principles of Polymerization" Odian, 3rd ed., Wiley Interscience. non-limiting examples of useful solute polymers include poly (acrylates), poly (methacrylates), poly (styrenes), elastomers such as rubbers (natural and / or synthetic) or styrene-butadiene block copolymers, polyurethanes, polyureas, polyesters, crystalline and non-crystalline polymers such as crystalline and non-crystalline poly-α-olefins, crystalline poly (methacrylate) and crystalline poly (acrylate), and mixtures thereof and the like Advantageously, this invention provides sensitive adhesive microspheres Compound pressure that can incorporate portions that normally react in the aqueous phase when used in monomeric forms s before the suspension polymerization of such monomers. Non-limiting examples of the solute polymers comprised of such aqueous reactive moieties include, but are not limited to polymers containing maleic anhydride, itaconic anhydride, 2-vinyl-4,4-dimethyl-2-oxazolin-5-one (VDM) and 2- (isocyanato) ethyl methacrylate. In addition, highly water soluble portions can also be incorporated, such as (meth) acrylic acid, N-vinylpyrrolidone, poly (ethylene) oxide macromonomer, (meth) acrylimide, 1,1-dimethyl-l (2-hydroxypropyl) amino methacrylimide, 1,1,1-trimethylamino methacrylimide, 1,1-dimethyl-l (2,3-dihydroxypropyl) amino methacrylimide and other water-soluble portions, such as propionate betaine N, N-dimethyl-N- ( β-methacryloxyethyl) ammonium, 4, 4, 9-trimethyl-4-azonia-7-oxo-8-oxa-dec-9-en-1 sulfonate, (Meth) acrylate, sodium acrylate, ammonium and maleic anhydride, for example can also be incorporated into the solute polymer used in the preparation of sensitive adhesive microspheres to composite pressure, provided that the solute polymer is essentially insoluble in water. Alternatively, the incorporation of polymers into composite pressure sensitive adhesive microspheres that typically can not be prepared by polymerization via free radicals or in the presence of water, is provided by the present invention. Also, copolymers of water-soluble and water-insoluble monomers can be used as solute polymers. Such solute polymers could include, for example, poly (styrene), poly (t-butyl) styrene, poly-α-olefins, such as poly (propylene), poly (ethylene), poly (hexene), poly (octadecene) ) and / or poly (octene), block copolymers of styrene-butadiene and the like, (such as Kratones), polyesters, polyureas, and various copolymers of soluble and insoluble monomers, such as styrene / acrylic acid, (t-butyl ) styrene / acrylic acid, (meth) acrylate / macromonomer poly (styrene) / acrylic acid (meth) acrylate / acrylic acid, (meth) acrylate / N-vinyl pyrrolidone, (meth) acrylate / macromonomer oxide poly ( ethylene), mixtures thereof and the like. Examples of suitable crystalline polymeric materials having segments backbone or polymerizable skeleton include, but are not limited to, polyesters, polytetrahydrofuran, lower polyolefins (e.g., olefins C2-C3), higher polyolefins (for example, C14-C20 olefins) and polyurethanes containing crystalline polyester segments. Also preferred are side chain crystalline polymeric materials derived from higher (α-olefin) monomers, such as poly (1-decene), poly (1-dodecene), poly (1-tetradecene) and poly (1-) hexadecene), and esters of higher vinyl such as tetradecanoate, vinyl hexadecanoate and vinyl octadecanoate vinyl. examples of suitable crystalline polymeric materials having crystallizable pendant portions (i.e., side chains) include, but are not limited a, poly (acrylate), poly (methacrylate), poly (acrylamide), poly (methacrylamide), poly (vinyl ester) and poly (α-olefins) polymers and copolymers having the following formula: wherein X is -CH2-, -C (0) 0- -OC (O) -, and -C (0) -NH-, etc., and n is sufficiently large to provide sufficient length and conformation of the side chain to form polymers containing crystalline domains or regions at room temperature. Suitable crystalline polymeric materials include, but are not limited to poly (dodecyl acrylate), poly (isotridecyl acrylate), poly (n-tetradecyl acrylate), poly (n-hexadecyl acrylate), poly (n- hexadecyl), poly (n-octadecyl acrylate), poly (methacrylate), poly (acrylate), poly (behenyl acrylate), poly (eicosamyl acrylate) and mixtures thereof. Of these, poly (n-octadecyl acrylate), poly (behenyl) acrylate, and mixtures and copolymers thereof are preferred.

Solvent Monomer / Polymer Ma.trz The second component of the composite microspheres are matrix polymers, a polymerization product of solvent mcnomers. The predominant solvent purses are essentially insoluble in water and can be comprised of one or more monomers. Usually, the alkyl (meth) acrylate monomers are monofunctionally more saturated (meth) acrylate esters, the alkali groups of which have from 4 to 14 carbon atoms. Such (meth) acrylates are oleophilic, dispersible in water, and are essentially insoluble in water. In addition, useful (meth) crilates are those which, as homopolymers, generally have a vitreous transition temperature less than about -10 ° C., or if a combination of monomers is used, such a combination could produce a copolymer or terpolymer having generally a glass transition temperature less than about -10 ° C. Non-limiting examples of such (meth) acrylates include, but are not limited to, isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, acrylate n-butyl, 2-ethylhexyl acrylate, isodecyl methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, methyl methacrylate, isononyl acrylate, isodecyl acrylate and the like, and combinations thereof. Preferred alkyl (meth) acrylate monomers include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl acrylates, 2-ethylhexyl acrylate, t-butyl acrylate, isobornyl acrylate, butyl methacrylate, sodium acrylate, n-butyl, sec-butyl acrylate and mixtures thereof. Various combinations of these monomers can be used. Suitable vinyl ester monomers for use in the present invention include, but are not limited to: vinyl 2-ethylhexanoate, vinyl laurate, vinyl pelargonate, vinyl hexanoate, vinyl propionate, vinyl decanoate, vinyl octanoate , and other monofunctionally unsaturated vinyl esters of linear or branched carboxylic acids, comprising from 1 to 14 carbon atoms, which as homopolymers have a glass transition temperature of less than approximately "=e -10 ° C. Preferred vinyl ester monomers include vinyl laurate, vinyl 2-ethylhexanoate, and mixtures thereof.

Other additional vinyl monomers, which, like homopolymers, have glass transition temperatures greater than about -10 ° C, such as vinyl acetate, acrylonitrile, styrene, and mixtures thereof and the like, can optionally be used in conjunction with one or more of the acrylate, methacrylate and vinyl ester monomers, provided that the vitreous transition temperature of the resulting polymer is less than about -10 ° C.

P-repairing of Adhesive Microspheres For composite microspheres or composite microparticles, free radical polymerization methods in suspension, such as those described in US Patent Nos. 3,691,140; 4,166,152 / 4,786,696; 5,045,569 and 5,508,313, and PCT Patent Application No. WO 96/01280 with modifications. One such method for preparing composite pressure sensitive adhesive microspheres could comprise the steps of: (a) preparing a solute polymer; (b) dissolving the solute polymer in at least one solvent monomer to provide a solute polymer / solvent monomer mixture; (c) dissolving an initiator in the solute polymer / solvent monomer mixture; (d) changing the reaction vessel with water, a surfactant, optionally, a stabilizer and the solute polymer / solvent monomer mixture to provide a reaction mixture; and (e) stirring the reaction mixture to create an emulsion and heat the emulsion while stirring. For composite microspheres, suspension polymerizations are typically carried out in the presence of a variety of emulsifiers, surfactants, Stabilizers and / or under particular process conditions of which includes the formation of, and prevention of, the agglomeration of particles (eg, microspheres having a diameter of about 1-300 microns). The composite microspheres may be solid, hollow or a combination thereof. As used in the present application: (1) 'hollow' means that they contain at least one vacuum or cavity, where 'cavity' means a space within the walls of a drop or microsphere when it is still in the suspension medium or dispersion before drying, and which thus contains any medium that has been used; 'empty' means a space completely within the walls of a polymerized microsphere, and 'drop' means the liquid state of the microspheres before the polymerization is completed; and (2) "solid" does not mean hollow, ie, essentially void-free or cavity-free The adaptation of those processes to prepare the composite microspheres of the present invention includes dissolving a solute polymer in a mixture of solvent monomer to a temperature such that the solute polymer component is dissolved followed by the formation of an emulsion and the subsequent polymerization of the monomer droplets.After polymerization takes place, the solvent monomers are converted to a matrix polymer, wherein the matrix polymer and the solute polymer (originally dissolved in the solvent monomer) are present within the boundaries of the microspheres, because the reactive portions that may be present in any one of the polymers, grafting sites between the polymers can be observed. In addition, the matrix polymer can be cross-linked and is available in a variety of methods to facilitate r crosslinking, such as ionizing radiation, peroxides, silanes, metal ions or monofunctional crosslinking agents. Preferably, multifunctional crosslinking agents are used, particularly for the preferred acrylate (co) polymers. Suitable multifunctional crosslinking agents include, but are not limited to, multifunctional acrylates, for example, 1,6-hexandioldi (meth) acrylate and 1,4-butandioldi (meth) acrylate, polymeric multifunctional (meth) acrylates, e.g., diacrylates of poly (ethylene oxide) or poly (ethylene oxide) dimethacrylate; polyvinyl crosslinking agents, such as substituted and unsubstituted divinibenzene; and bifunctional urethane acrylics. These multifunctional crosslinking agents can be used in a variety of combinations. Preferred multifunctional crosslinking agents are those selected from the group consisting of acrylic or methacrylic esters of diols such as butanediol, triols such as glycerol, tetroles such as pentaerythritol, and mixtures thereof. When multifunctional crosslinking agents are used, one or more are used in an amount of up to about 0.15 weight percent equivalent, preferably up to about 0.1 weight percent equivalent, of the total polymerizable composition. The 'percent equivalent weight%' of a given compound is defined as the number of equivalents of that compound divided by the total number of equivalents in 100 times the total composition, where one equivalent is the number of grams divided by the weight The equivalent weight is defined as the molecular weight defined by the number of polymerizable groups in the monomer (in the case of those monomers with only one polymerizable group, the equivalent weight = molecular weight) Surfactants will typically be present in the mixture of reaction, preferably in an amount of not more than about 10 parts by weight per 100 parts by weight of polymerizable monomer, preferably not more than about 5 parts by weight, and most preferably in the range of 0.5 to 3 parts by weight weight per 100 parts by weight of polymerizable monomer Useful surfactants (also known as emulsifiers) include anionic surfactants cationic or non-ionic and include but are not limited to anionic surfactants, such as alkylaryl ether sulphates and sulphonates such as alkylaryl ether sodium sulfate, for example TritonMR X200, available from Rohm and Haas, alkylaryl polyether sulphates and sulphonates such as sulfates and alkylarylpoly (ethylene oxide) sulfonates, preferably those having up to about 4 repeating units of ethyleneoxy, and alkyl sulfates and sulphonates such as sodium lauryl sulfate, ammonium lauryl sulfate, triethanolamine lauryl sulfate, and hexadecyl sulfate. sodium, alkyl ether sulphates and sulphonates such as ammonium lauryl ether sulfate, and alkyl polyether sulphates and sulphonates such as alkyl poly (ethylene oxide) sulfates and sulfonates, preferably those having up to about 4 ethyleneoxy units. Alkyl sulfates, alkyl ether sulfates and alkylaryl ether sulphates are preferred. Additional anionic surfactants may include, for example, alkylaryl sulfates and sulfonates, for example sodium dodecylbenzene sulfate and sodium dodecylbenzene sulfonate, sodium and ammonium salts of alkyl sulfate, for example sodium lauryl sulfate and ammonium lauryl sulfate; nonionic surfactants, such as ethoxylated eloyl alcohol and polyoxyethylene octylphenyl ether; and cationic surfactants such as a mixture of alkyl dimethylbenzyl ammonium chlorides wherein the alkyl chain contains from 10 to 18 carbon atoms. Amphoteric surfactants are also useful in the present invention and include, for example, sulfobetaines, N-alkylaminopropionic acids and N-alkylbetaines. Optionally, a polymeric stabilizer can be used and if used it should be present in an amount of up to about 0.05 and about 3 parts by weight per 100 parts by weight of the microspheres, preferably from about 0.1 to about 1.5 parts by weight per 100 parts by weight of the microspheres. Advantageously, the presence of stabilizers allows the use of relatively low amounts of surfactant to still obtain the microspheres.

Any polymeric stabilizer that effectively provides sufficient stabilization of the final polymerized droplets and prevents agglomeration within a suspension polymerization process is useful in the present invention. Exemplary polymeric stabilizers include salts of polyacrylic acids of an average molecular weight of more than 5000 (eg, ammonium, sodium, lithium and potassium salts), polyvinyl alcohol, carboxy-modified polyacrylamides (eg, Cyanamer ™ A-370 from American Cyanamid), copolymers of acrylic acid and dimethylaminoethyl methacrylate and the like, polymeric quaternary amines (eg, General Analine and Films Gafquat ™ 755, a copolymer of quaternized polyvinyl pyrrolidone, or 'JR-400', from Union Carbide, cellulosic material substituted with quaternized amine) , cellulosic materials, and cellulosic materials modified with carboxy (for example, Natrosol "Hercules CMC Type 7L, carboxymethylcellulose sodium.) Initiators that affect polymerization are those that are normally suitable for the free radical polymerization of acrylate monomers Examples of such initiators include thermally activated initiators such as azo compounds, hydroperoxides, peroxides and the like and photoinitiators such as benzophenone, benzoin ethyl ether and 2,2-dimethoxy-2-phenyl • acerophenone. Other suitable initiators include lauroyl peroxide and bis (t-butyl cyclohexyl) peroxy dicarbonate. The initiator is present in a sufficient catalytically effective amount to carry out a high monomer conversion in a predetermined time interval and in the temperature range. Typically, the initiator is present in amounts ranging from about 0.05 to about 2 parts by weight per 100 parts by weight of the starting material of the microsphere composition.

Preparation of Pressure Sensitive Adhesives The combination of at least one solute polymer of at least one solvent monomer was chosen in such a way that a solute polymer can be dissolved in the solvent monomer.

In addition, the combination of solvent monomer and solute polymer results in a polymeric microsphere composed of solute polymer / matrix polymer that is inherently pressure sensitive adhesive. The mixture of solute polymer and matrix polymer can have a wide range of morphologies, which depend on the compatibility of two or more polymers in the microsphere. Such morphologies include homogeneous mixtures of polymers and separate phase compositions in which the different polymers or polymer blends exist in their own phases. When solute crystalline polymers are used, a preferred morphology is one in which a crystalline solute polymer is dispersed in a matrix polymer. Optionally, adjuvants, such as rheology modifiers, colorants, fillers, stabilizers, tackifiers, plasticizers, latex binders and various polymeric additives can be used. If adjuvants are used, the amounts used in the adhesive mixture are effective amounts for the known uses of such adjuvants.

Adhesive Items The cuts used as substrates for the adhesive articles may be materials that are conventionally used as a tape backing or may be of another flexible material. .udies supports include, but are not limited to, those made from materials selected from the group consisting of poly (propylene), poly (ethylene), poly ("vinyl chloride"), polyester (eg, poly (ethylene terephthalate). ), such as those available under the commercial designation of "Scotch" film 8050 from 3M)), polyamide films such as those available from DuPont Co., Wilmington, DE, under the trade designation "KAPTON", cellulose acetate, and ethyl cellulose. The supports can also be woven fabric formed from strands of synthetic and natural materials such as cotton, nylon, rayon, glass or ceramic material, or be of non-woven fabric such as fabrics quilted with nylon and synthetic or natural fibers or mixtures thereof. In addition, the support can be formed of materials selected from the group consisting of metal, metallized polymeric film and ceramic sheet material. Preferred materials include, but are not limited to, plastics such as polyethylene, polypropylene, polyesters, cellulose acetate, polyvinyl chloride and polyvinylidene fluoride, as well as paper and other substrates coated or laminated with such plastics. These coated papers or thermoplastic films are often siliconized or otherwise treated to impart improved release characteristics. One or both sides of the supports or liners could have such removable characteristics. Generally, the support or substrate material is from about 50 μm to about 155 μm thick, although thicker and thinner support or substrate materials are not excluded. Typical coating methods that can be used to prepare the adhesive articles according to the present invention include solvent coatings and water-based coatings and techniques commonly known to those skilled in the art. Particularly useful articles prepared using the pressure sensitive adhesive microspheres of the present invention include repositionable adhesive products such as repositionable paper products, repositionable indicator tapes, repositionable sheets, repositionable cement bars and the like, but may also include other industrial products Non-repositionable, commercial, and medical adhesives. The objects and advantages of this invention are best illustrated by means of the following examples. The materials and particular amounts thereof set forth in these examples as well as other conditions and details, should not constitute an undue limit of this invention. All materials are commercially available except where otherwise stated or evident. All parts and percentages used here are by weight, unless otherwise specified.

Example Test Methods Adhesive Transfer Adhesive transfer is defined as the amount of adhesive that is transferred to an applied substrate when the adhesive-coated sheet is peeled off or removed from the substrate. The test was conducted by adhering a three quarter inch wide (1.9 cm) strip of adhesive coated sheet to a clean area of a commercially available clay coated paper such as Kromekote ™ using a release tester and TLMI adhesive. it was allowed to remain in contact with the Kromekote1 for 30 seconds and then it was removed at a 90 ° angle at a constant speed of 225 centimeters / minute (90 inches / minute) .The strip coated with clay was then analyzed by a processor. images were recorded through a video camera and the percentage coverage of the adhesive of the observed area was recorded.10 fields of vision were analyzed and then averaged for each test sample.The test was repeated and the results were reported as average.

Adhesion Adhesion is the force required to remove a flexible sheet material coated with an adhesive from a test panel measured at a specific angle and speed of removal. In the examples, this force is expressed in grams per width of the sheet coated with adhesive.

Adhesion to Polyester Adhesion to the polyester film was measured by applying a 1.25 inch (3.2 cm) wide strip of polyester film to the surface of a sample coated with adhesive, which was fixed on a test plate horizontal. A 4.5 lb. (2 kg) hard rubber roller was used to apply the strip. The free end of the polyester film was attached to a load cell of the adhesion tester, so that the angle of removal was 90 ° relative to the horizontal test plate. The polyester strip was peeled from the adhesive at a constant rate of 12 inches (31 cm) per minute. A reading of the load cell in grams per 1.25 inches (3.2 cm) was recorded. The test was repeated and the data was reported as the average number of trials.

Adhesion to Bond Paper Adhesion is the force required to remove a coated sheet from a bond paper substrate at a specific angle and speed of removal. In the examples this force was expressed in grams per one inch in width of the coated sheet. The procedure followed is: A strip, one inch wide, of coated sheet was applied to the horizontal surface of 20 lb (8.9 kg) bond paper. A 4.5 Ib (2 kg) hard rubber roller was used to firmly apply the strip to the bond paper. The free end of the coated sheet was attached to the load cell of the adhesion tester, so that the angle of removal was 90 °. The test plate was then held in the jaws of the tensile testing machine, which is capable of moving the plate away from the load cell at a constant speed of 30.48 cm (12 inches) per minute. A load cell reading was recorded in grams per inch (2.54 cm) of coated sheet. The test was repeated and the data was reported as the average number of trials.

Static Cutting Pitch The static cut test measures the time in minutes required to pull a standard area of adhesive-coated laminate from a flat test panel under the stress of a standard, constant load, and in which the effort is at a direction parallel to the surface of the test panel. Stainless steel test panels were used in the examples. The test was conducted on strips of adhesive-coated laminate, which were applied to a test panel with a 4.5-pound (2-kg) hard rubber roller so that any of a 1.0-inch by 1.5-inch portion (2.54 x 3.81 cm) or one of 1.0 inches by 1.0 inches (2.54 x 2.54 cm) of each strip is in contact with the panel. The panel with the attached coated strip, it was kept in a support in an almost vertical position, so that the panel would form an angle of 92 ° in relation to the horizontal. The 2 ° deviation from the vertical position was used to negate any detachment forces, thus ensuring that only the shear forces were measured. A 1 kg weight was attached to the free end of the adhesive coated strip and the time taken for the coated strip to separate from the test panel in minutes was recorded. The test was repeated and the data was reported as the average number of trials.

% Solvent Soluble Portion To determine the content of soluble solvent prepared microspheres, the following procedure was used. One gram of suspension of microspheres in water was dried in a vacuum oven without heating. After heating, 100 ml of n-heptane was added, and stirred for 24 hours. After stirring, the dispersion was poured through a filter paper (30 micrometer pore) to remove the insoluble content. The filtrate was then dried in an oven at 100 ° F (37.8 ° C). The weight of the dry filtrate divided by the dried suspension microspheres is the% solvent soluble polymer content. The test was repeated and the data was reported as the average number of trials.

Glossary IOA isooctyl acrylate AA acrylic acid ODA octadecyl acrylate 1,4-BDA 1,4-butanediol diacrylate mv average volume sd standard deviation μm micrometers VDM 2-vinyl-4,4-dimethyl-2-oxazolin-5-one NVP N-vinyl pyrrolidone PEO-750 poly (ethylene oxide) terminated acrylate-terminated molecular weight 750 mg milligrams "repositionable" refers to the ability to repeatedly adhere and remove from the substrate without substantial loss of adhesion capacity Mw average molecular weight in weight AIBN 2, 2 '-azobis (2-methylpropionitrile) Examples 1-7 Preparation of the IOA / AA 80/20 Solute Copolymers used in Examples 1-7 A portion of 26 grams of IOA, 9 grams of AA, 180 grams of 2-butanone and 1 ml of a solution of 0.585 grams of dissolved AIBN in 10 ml of 2-butanone were added to 500 ml amber bottles. The solutions were tested with nitrogen for five to ten minutes and then the bottles were sealed with lids. The bottles were placed in an Atlas Launder-o-meter ™ water bath, heated to 65 ° C and stirred overnight. The bottle was then cooled and the solution was evaporated to dryness in a Teflon coated tray, first at room temperature, and then in a forced air oven at 55 ° C to give a slightly yellow IOA / AA 80/20 copolymer, transparent. The polymer was characterized by gel permeation chromatography and was found to have an Mw of 61,000. This polymer was used in Examples 1-4. A similar IOA / AA copolymer was prepared with an Mw of 86,000 by repeating the polymerization at a slightly higher percentage of solids (33%) and with a lower amount of AIBN (0.066% monomer). This polymer was used in Examples 5 and 6.

Example 1 This example describes the preparation of a composite MSA containing 25% solute copolymer of IOA / AA 80/20 and 75% poly (IOA) matrix copolymer. A 2 L separation reaction flask equipped with a mechanical stirrer, temperature controller, heating lamp, nitrogen inlet and reflector was charged with 600 grams of DI water and 4 grams of Siponate DS-10 (trade name for sodium dodecylbenzenesulfonate commercially available from Alcolac, Inc.), was heated to 65 ° C and purged with fluid nitrogen. In a separate vessel, 0.929 grams of Lucidol 70 (trademark for 70% active benzoyl peroxide available from Pennwalt Corporation) and 50 grams of 'IOA / AA 80/20 solute copolymer and 150 grams of IOA were dissolved. After reaching equilibrium of the aqueous solution at 65 ° C, the stirring speed was set at 450 rpm and the solution of IOA / copolymer / benzoyl peroxide was added. The solution was purged with fluid nitrogen for an additional 5 minutes, sealed to the atmosphere via the use of a sparger and allowed to react at 65 ° C for 8 hours. An exothermic reaction was observed, having a peak temperature of ~ 68 ° C, 24 minutes after the addition of the monomer solution. After a period of 8 hours, the solution was cooled to room temperature and filtered through a cheese screen. Microscopy indicated the presence of solid microspheres. The particle size analysis indicated an average volumetric diameter of 68 microns. It was determined that the portion of solvent-soluble microspheres was 38%.

Examples 2-C7 Examples 2-C7 were prepared according to the procedure described in Example 1, except that the amount of IOA / AA 80/20 solute copolymer was varied to make composite pressure sensitive adhesive microsphere compositions which they contained 15, 5, 3, 1.5, 0.5 and 0% of the IOA / AA 80/20 copolymer. The results for the particle size and% of the soluble portion of solvent are summarized in Table 1.

Table 1 Example 1-C7 Composite microspheres prepared with varying amounts of an IOA / AA 80/20 copolymer Ex. Lucidol IOA Copolymer Copolymer% Size of 70 IOA / AA IOA / AA Particle Portion (g) 80/20 80/20 ((μllmm)) Soluble (g) of (g):%) Solvent 0. 929 150 50 25 68 38 0. 831 170 30 15 40 38 0. 929 190 10 34 23 0. 978 194 34 25 0. 978 197 1.5 34 22 0. 978 199 0.5 42 22 C7 0.978 200 58 28 Operation of the coating / adhesive of the adhesives prepared in Examples 1-C7 (A) Solvent-Based Coatings The adhesives described in Examples 1-C7 were evaluated for their adhesive performance. Each of the pressure-sensitive adhesive microspheres was isolated from water via the addition of isopropyl alcohol to the suspension, which resulted in massive coagulation. The coagulated polymer was dried to approximately 80% solids and dispersed in enough heptane to obtain the 8% solids dispersion. The samples were stirred overnight and then mixed with a mechanical stirrer for several minutes to ensure uniform dispersion of the microspheres. The heptane dispersions were coated on primed paper using a 4 mil space (0.1 mm) between the paper and the coating knife. The coatings were tested for adhesion to polyester (g / 1.25"og / 3.175 cm), adhesion to bond paper (g / inch or 2.54 cm), adhesive transfer and static cutting to stainless steel (1.5" x 1.0"x 1 kg x 1 kg or 3.81 x 3.81 cm x 1 kg.) The results are summarized in Table 2.

Table 2 Adhesive properties for Examples 1-C7 coated on primed paper Ex. Copolymer Adhesion Adhesion% IOA / AA Cut to al Static Transfer Paper 80/20 Adhesive Bond Polyester (min) (g / 1"or 1.5" x 1.0" %) (g / 1.25"g / 2.54 x 1 kg or or g / 3.175 cm) 3.81 cm x 2.54 cm cm) x 1 kg 1 25 2 2 0.01 0 2 15 33 12 0.5 2150 3 5 81 30 4 3 98 33 2.7 10,000+ 1.5 104 42 1.2 10,000+ 6 0.5 77 52 4.0 230 C7 0 88 54 13.1 144 The data in Table 1 illustrate the improvements in adhesive properties that were obtained using the methods described in this invention. For example, the operation of the static cut was increased much more than 144 minutes to more than 10,000 minutes by adding a small amount (1.5 or 3.0%) of IOA / AA 80/20 copolymer, while adhesion to polyester and paper Bond remained good. Removable adhesive with high cut resistance has uses in many applications, such as removable labels, signs and ribbons. Adhesion data to polyester and bond paper illustrated the ability to control adhesion to different surfaces. For example, at low charges of IOA / AA copolymer, the adhesion to the polyester was increased, while adhesion to the bond paper diminished. Such "differential adhesion" is desirable for applications where low adhesion to delicate substrates is desired to superior adhesions to more durable substrates. It was found that the adhesive transfer percent decreases significantly when solute copolymer is added to the microsphere. Only a small amount of solute copolymer is necessary to improve adhesive transfer to a large extent. This is an advantage since the clean removal of the substrates is improved. (B) Water-Based Coatings Examples 1-C7 were coated without water to demonstrate that similar improvements in performance can be observed when compared to solvent base coatings. Each adhesive was allowed to separate after standing in a phase rich in microspheres and poor in microspheres. A portion of the phase rich in microspheres was diluted to 50% solids via the addition of deionized water, dispersed via stirring and coated through a 1 mil space (25.4 μm) on a 3M polyester film product "Scotch 8050". Coated samples were tested to determine adhesive performance; the results are summarized in Table 3.

Table 3 Table 3 (Continued) The data in Table 3 were reported as averages of two or three replicates unless the value is denoted by an "*", in which case only one replica was carried out.

EXAMPLE 8 This example describes the preparation of microspheres containing 20% 80.8 IOA / NVP solute copolymer (Mw = 133,000) and 80% poly (IOA) matrix polymer. The IOA / NVP copolymer was first prepared by solution polymerization in a manner similar to that used for the preparation of IOA / AA copolymer in Examples 1 to 4. A 2L separation reaction flask was charged with 325 grams of deionized water, 8.75 grams of Triton ™ X-200 (trade name for a 30% dispersion of alkyl aryl polyethylene sulfonate solids commercially available from Rohm and Haas Company) and 7.0 grams of Goodrite ™ K-702 (trade name for a aqueous solution at 25% solids of polyacrylic acid, weight average molecular weight of 240,000, commercially available from BF Goodrich Company). The solution was stirred at 450 rpm, neutralized to pH 7 with concentrated ammonium hydroxide, and heated to 65 ° C under a nitrogen purge. In a separate vessel, 655 mg of LucidolMR 70 dissolved in 58 grams of IOA was added; 117 grams of a 30% solution of 80/20 IOA / NVP copolymer dissolved in IOA. The resulting solution was mixed for 10 minutes and then added to the hot aqueous solution. The solution was purged with nitrogen, and allowed to react at 65 ° C for 45 minutes and then at 80 ° C for 2 hours. The solution was cooled and filtered through a cheese screen. or clots were observed. Microscopy indicated the presence of solid microspheres. The particle size analysis indicated an average volumetric diameter of 69 μm. The elemental analysis of the adhesive indicated a nitrogen content of 0.51%, which was almost identical to the theoretical amount of 0.50%.

Example 9 This example describes the preparation of microspheres containing 10% solute copolymer of IOA / PEO-750 and 90% poly (IOA) matrix polymer. PEO-750 is an acrylate-terminated poly (ethylene oxide) macromonomer having an average molecular weight of 750. First an IOA / PEO-750 copolymer was prepared by adding 14 grams of IOA, 6 grams of PEO-750, 0.06 grams of Vazo 64 (trade name for 2, 2 '-azobis (2-methylpropannitrile), commercially available from DuPont Co.), 0.3% CBr4 and 58 grams of ethyl acetate in a bottle. The solution was degassed with nitrogen, the bottle was capped and placed in a Launder-o-meter ™ for 22 hours at 60 ° C. After the reaction, the ethyl acetate was removed from the bottle via evaporation. The polymeric microspheres were prepared by loading a baffled reactor, preparing one liter with 6 grams of Standapol1 (commercial name for a solution of 29% solids lauryl sulfate commercially available from Henkel Corp.) and 450 grams of deionized water . In a separate vessel, 4.5 grams of AA, 15 grams of IOA / PEO-750 70/30 copolymer, 710 mg of Lucidol-75 (trade name for a 75% active benzoyl peroxide available from Pennwalt Corporation) were dissolved in 133.5 grams of IOA. The IOA mixture was then added to the reactor and the resulting emulsion was homogenized until the average droplet size of the monomer was approximately 1 micrometer in diameter. The solution was stirred at 400 rmp, heated to 55 ° C, degassed with argon and allowed to react for 22 hours. After the reaction, there was little coagulation in the reactor. Analysis by microscopy indicated the presence of microspheres from 2 to 10 micrometers in diameter.

Example 10 This example describes the preparation of microspheres containing 25% of a 75/25 IOA / PEO-750 solute copolymer and 75% of a poly (IOA) matrix polymer. First, an IOA / PEO-750 75/25 copolymer was prepared by combining 264 grams of IOA, 88 grams of PEO-750, 720 grams of 2-butanone and 0.35 grams of AIBN in a large beaker. The solution was stirred until the initiator dissolved, divided into four 16-ounce narrow-mouth amber bottles (453.6 ml) and cured with nitrogen. Each bottle was immediately capped and then placed in a Launder-o-meter ™ at 65 ° C and allowed to react overnight. The polymer was isolated by removing the solvent via evaporation. The polymeric microspheres were prepared by dissolving the IOA / PEO-750 75/25 copolymer in 25% solids IOA. To a portion of 59.75 grams of this solution were added 0.8 grams of Lucidol 70 and the mixture was stirred until the initiator dissolved. A separating reaction flask was charged with 740 grams of DI water and 4 grams of Siponate DS-10. The solution was heated to 70 ° C and stirred at 400 rpm. Both solutions were purged with nitrogen and then the IOA mixture was added to the flask. The temperature was increased to 80 ° C. 2 hours later, the solution was cooled to room temperature. Analysis by microscopy indicated the presence of microspheres from 3 to 40 micrometers in diameter.

Example 11 This example describes the preparation of microspheres with a content of 13% of a solute copolymer of IOA / VDM (VDM = 2-vinyl-4,4-dimethyl-2-oxazolin-5-one) 80/20 and 86% of a poly (IOA) matrix polymer. First an 80/20 IOA / VDM was prepared by combining 240 grams of IOA, 60 grams of VDM, 600 grams of 2-butanone and 0.6 grams of AIBN in a large beaker. The solution was stirred until the initiator dissolved, divided between four 453.6 ml (16 ounce) narrow mouth amber bottles and purged with nitrogen. Each bottle was capped immediately and then placed in a Launder-O-meter at 65 ° C and allowed to react overnight. The polymer was isolated by removing the solvent via evaporation. The polymeric microspheres were prepared by dissolving 41 grams of the IOA / VDM copolymer in 272 grams of IOA. A portion of 239 grams of the solution was mixed with 0.8 grams of Lucidol 70 and allowed to mix at ~ 45 ° C until dissolved. The resulting solution was added to a reaction flask which contained 740 grams of DI water and 4.5 grams of Siponate DS-10 surfactant at 70 ° C. The resulting mixture was stirred at 450 rpm. The temperature was raised to 80 ° C for 2 hours and then allowed to cool to room temperature. Little or no agglomeration was observed. Analysis by microscopy indicated the presence of well-formed solid spheres. The particle size analysis indicated an average volumetric diameter of 34 micrometers.

Example 12 This example describes the preparation of a microsphere with a content of 10% of a polyhexene solute polymer and 90% of a poly (IOA) matrix polymer. A 2 L separation reaction flask was charged with 730 grams of DI water, 4.4 grams of Siponate DS-10, 9.6 grams of Acumer 1530 (the trade name for a 25% aqueous solution of poly (acrylic acid) solids) with a weight average molecular weight of 190,000 commercially available from Rohm and Haas) and sufficient concentrated ammonium hydroxide to neutralize the solution at pH 7. The solution was stirred at 520 rpm, heated to 65 ° C and purged with nitrogen. To this solution was added a solution of 24 grams of poly (hexene) (obtained from Eastman Kodak, Mw = 96,000) and 800 mg of Lucidol 70 dissolved in 215 grams of IOA. The solution was purged with fluid nitrogen for an additional four minutes and then the reactor was sealed to a sparger. The mixture was allowed to react at 65 ° C for 1 hour, and then at 80 ° C for 2 hours. The mixture was cooled to room temperature and filtered through a cheese screen. No clots were observed. Analysis by microscopy indicated the presence of microspheres. The particle size analysis indicated a symmetric distribution of sizes with an average volumetric diameter of 38 micrometers.

Example C13 Example C13 was prepared in a manner similar to that of Example 12 except that polymeric stabilizer (Acumer 1530 neutralized) was not used. In contrast to Example 12, Example C13 produced predominantly agglomerated microspheres that could not be filtered through the cheese screen.

Example C14 Example C14 was prepared in a manner similar to that of Example C13 except that no polyhexene was added. A suspension of microspheres la was obtained. which was easily filtered through a cheese screen. Examples 12, C13 and C14 show that the composite pressure sensitive adhesive microspheres may be more difficult to produce than the non-composite microspheres.

Example 15 This example describes the preparation of microspheres containing 3% polyokene-polyol solute and 97% poly (IOA) matrix polymer. A 2 L separation reaction flask was charged with 739 grams of DI water, 9.6 grams of Acrysol A-3 (the trade name for a 25% aqueous solution of poly (acrylic acid) solids with an Mw 150,000, commercially available from Rohm and Haas Company), 4.5 grams of Siponate DS-10 and enough concentrated ammonium hydroxide to neutralize the solution at pH 7. The solution was stirred at 500 rpm. A solution of 800 mg of Lucidol 70 and 7.2 grams of polyokene (obtained from Eastman Kodak) was added.; Mw = 1,100,000) dissolved in IOA. The mixture was heated to 70 ° C and purged with nitrogen. An exothermic reaction was observed at a peak temperature of 76 ° C after about 15 minutes. The reaction was then stirred for 2 h at 80 ° C, cooled to room temperature and filtered through a cheese screen. No clots were observed. The particle size analysis indicated an average volumetric diameter of 52 micrometers.

Example 16 This example describes the preparation of microspheres containing 20% poly (IOA) as a solute polymer and 80% of a poly (IOA) matrix polymer. A portion of 300 grams of DI water, 2 grams of Siponate DS-10 and 4 grams of Acumer 1530 and sufficient concentrated ammonium hydroxide to neutralize the solution at pH 7 were added to a 2 L separation reaction flask, and heated at 65 ° C under flowing nitrogen. A solution of 20 grams of poly (IOA) (Mw = 250,000), and 270 mg of Lucidol 70 dissolved in 80 grams of IOA was added to the aqueous solution and stirred at 470 rpm. 1 hour later, the temperature was raised to 80 ° C for 2 hours. The solution was cooled to room temperature and then filtered through a cheese screen. No clots were observed. Analysis by microscopy indicated the presence of solid microspheres. The particle size analysis indicated an average volumetric diameter of 51 micrometers.

Example 17 This example describes the preparation of microspheres containing 5% Kraton 1111 rubber as the solute polymer and 95% poly (IOA) as the matrix polymer. The Kraton was dissolved in 10% solids IOA by stirring overnight. A 75 gram portion of this solution was added to a solution of 680 mg of Lucidol 75 dissolved in 75 grams of IOA and mixed until homogeneous. A 1 L separation reaction flask was then charged with 407 grams of DI water, 30 grams of a 10% solution of ammonium lauryl sulfate (Stepanol AM-V, which had been diluted with DI water) and dried. grams of 11.5% poly (ammonium acrylate) of Goodrite K-702, which had been diluted with DI water and neutralized with concentrated ammonium hydroxide). The IOA solution was added. The solution was stirred at 450 rpm, heated to 65 ° C and degassed with nitrogen. An exothermic reaction was detected with a peak temperature of 67 ° C after 30-45 minutes. 5 hours later at 65 ° C, the solution was cooled to room temperature and filtered through a cheese screen. No clots were observed. Analysis by microscopy indicated the presence of microspheres with a small number of small holes. The particle size analysis indicated an average volumetric diameter of 72 μm.

Example 18 This example describes the preparation of a microsphere containing 4% poly (styrene) as the solute polymer. A 3.0 gram portion of polystyrene (Mw = 5000) and 0.25 grams of VAZO 52 were dissolved in 70.25 grams of IOA. A 1 L separation reaction flask was charged with 450 grams of DI water, 3.0 grams of acrylic acid and 5.0 grams of Standapol A. The solution was then neutralized to pH 7 with ammonium hydroxide. The IOA / polystyrene solution was added to the aqueous solution. The mixture was stirred at 400 rpm, heated to 55 ° C and degassed with argon. 5 hours later at 55 ° C, the reactor was emptied and the suspension was filtered through the cheese screen. No clots were observed. The analysis by optical microscopy indicated the presence of microspheres with an average volumetric diameter of 10 to 20 micrometers that contained many small inclusions of approximately 2 micrometers in diameter.

Example 19 This example describes the preparation of microspheres containing 5% poly (styrene) terminated in -CH2-CH2-OH as the solute polymer. A 1 L indented flask was charged with 880 ml of deionized water and 3.60 grams of acrylic acid, and neutralized to pH 7 with concentrated ammonium hydroxide. To this solution was added a solution of 6.0 grams of poly (styrene) terminated in -CH2-CH2-OH with an Mw of 10,000 and 0.30 grams of vazo 52 dissolved in 110.4 grams of IOA. The mixture was stirred at 350 rpm and degassed with argon. A 2.0 gram portion of Siponate DS-10 was added. The solution was degassed with argon for an additional 10 minutes and heated to 55 to 65 ° C. A sample taken 45 minutes later showed the presence of microspheres 10-20 micrometers in diameter containing numerous small inclusions of approximately 2 micrometers in diameter.

Example 20 Example 20 was repeated in a manner similar to 19 except that 4.4 grams of a branched three-arm polystyrene with an Mw of 120,000 was used in place of the poly (styrene) terminated with -CH2-CH2-OH. Microspheres 10-20 micrometers in diameter were produced, which contained numerous small inclusions of approximately 2 micrometers in diameter.

Example 21 The example describes the preparation of a microsphere having 5% poly (vinyl ethyl ether) as the solute polymer Poly (vinyl ethyl ether) (obtained from Scientifíc Polymer Products, Inc., catalog No. 638, was dissolved. ) in 10% solids IOA A 75 gram portion of this solution was added to a solution of 680 mg Lucidol 75 dissolved in 75 grams of IOA The resulting solution was added to a 1 L separation reaction flask. which had been loaded with 406 grams of DI water, 30 grams of a 10% solution of ammonium lauryl sulfate (Stepanol AM-V, which had been diluted with DI water) and 13 grams of a solution of poly (acrylate) ammonium) to 11.5% (Goodrite K702, which had been diluted with DI water and neutralized with concentrated ammonium hydroxide) The mixture was heated to 65 ° C, degassed with nitrogen and allowed to react for 6 hours. cooled to room temperature and filtered through a cheese sieve No clots were observed. Analysis by microscopy indicated the presence of microspheres that contained small holes or inclusions. The particle size analysis indicated an average volumetric diameter of 55 μm. The addition of isopropyl alcohol to a small portion of the suspension resulted in coagulation; a sticky polymer mass was obtained.

Example 22 The example describes the preparation of a microsphere containing 5% poly (isobornyl acrylate) as the solute polymer and 95% of an IOA / AA 96/4 matrix copolymer. In a 1 L separation reaction flask, a 1.05 gram portion of a 10% poly (isobornyl acrylate) solution (obtained from Scientific Polymer Products, Inc.) dissolved in IOA was added and the solution mixed well . Then a portion of 407 grams of DI water, 30 grams of a 10% aqueous solution of ammonium lauryl sulfate (Stepanol ™ AM-V, which had been diluted with DI water) and 13 grams of a poly solution was added. (ammonium acrylate) at 11.5% (Goodrite K702, which had been diluted with DI water and neutralized with concentrated ammonium hydroxide). The mixture was stirred at 450 rpm, heated to 65 ° C, purged with nitrogen and then allowed to react at 65 ° C for about 9 hours. An exothermic reaction was observed with a peak temperature of 72 ° C. The reaction was stirred at room temperature and filtered through the cheese screen. No clots were observed. Analysis by microscopy indicated the presence of microspheres which had a small amount of inclusions of approximately 1-5 micrometers in diameter. The particle size analysis indicated an average volumetric diameter of 30 micrometers.

Example C23 Example 22 was repeated except that acrylic acid was not used in Example C23. The reaction was agglomerated and could not be filtered through a cheese screen.

Example 24 This example describes the preparation of microspheres containing 2% of an IOA / AA 98/2 copolymer as the solute copolymer. A 1 L indented flask was charged with 880 ml of deionized water, 3.60 grams of acrylic acid and sufficient concentrated ammonium hydroxide to neutralize the solution to pH 7. To this solution were added 12.0 grams of Standapol ™ A and a solution of 4.3 grams of IOA / AA 98/2 copolymer and 0.86 grams of LucidolMR 70 dissolved in 220 grams of IOA. The mixture was degassed with argon, stirred vigorously, heated to 55 to 65 ° C, and allowed to react overnight. A suspension of hollow microspheres with simple inclusions with a relatively large size was obtained.

Example C25 This example was prepared in a manner similar to that of Example 24 except that IOA / copolymer 92/2 was not added. A suspension of solid microspheres was obtained.

Example 26 This example describes the preparation of microspheres containing 5% poly (ODA) as the solute polymer and 95% poly (IOA) as the matrix polymer. A one liter glass reactor was charged with 7.5 grams of an aqueous solution of polyacrylic acid at 20% by weight solids, 450 grams of deionized water, enough concentrated ammonium hydroxide to neutralize the solution at a pH of 7 and 6.0 grams of Standapol A. The reactor was heated to 65 ° C while stirring at 600 rpm. In the glass vessel, 7.5 grams of poly (ODA) were dissolved in 142.5 grams of IOA and 0.04 grams of 1,4-BDA, with heating. After the poly (ODA) was dissolved, 0.67 grams of Lucidol 70 was dissolved in the monomer-polymer solution. When the reactor content reached 65 ° C, the poly (ODA) solution was added to the monomers containing the initiator while maintaining the agitation speed at 600 rpm. After 15 hours at 65 ° C, the contents of the reactor were allowed to cool to room temperature. Several drops of microsphere suspension were dried on a glass plate. The microspheres adhered to the touch. Optical microscopy showed microspheres with an average diameter of approximately 40 micrometers.

Examples 27-28 The following examples were prepared according to the procedure described in Example 26 with the amounts of monomers and initiators shown in Table 4.

Table 4 Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention should not be unduly limited to the illustrative embodiments set forth hereinbefore. All publications and patents are incorporated herein by reference to the same extent as if each publication or individual patent was specifically and individually indicated as incorporated by reference.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (13)

1. Compound pressure-sensitive adhesive microspheres, characterized in that they comprise two or more water-insoluble polymers that are present within the limits of polymeric microspheres.

2. Composite pressure sensitive adhesive microspheres according to claim 1, characterized in that the microspheres are the product of the reaction of (1) at least one solute polymer and (2) at least one solvent monomer, wherein the polymer solute can be dissolved in the solvent monomer and the polymerized solvent monomer is a matrix polymer.

3. Composite pressure sensitive adhesive microspheres according to claim 2, characterized in that the solute polymer is prepared from (1) monomers that are water soluble or do not react in water, (2) the monomer combination soluble in water or reacting with water and insoluble in water or not reacting in water, with the proviso that the solute polymer is essentially insoluble in water, (3) monomers that are not polymerizable via free radical polymerization or (4) ) mixtures thereof.

4. Composite pressure sensitive adhesive microspheres according to claim 3, characterized in that the monomers used to prepare the solute polymer and the matrix polymer are the same monomer, but the solute and matrix polymers have different molecular weights or crosslink densities .

5. Composite pressure sensitive adhesive microspheres according to claim 3, characterized in that the solute polymer and the matrix polymer have different vitreous transition temperatures. The composite pressure sensitive adhesive microspheres according to claim 2, characterized in that a solvent monomer is essentially insoluble in water and is comprised of one or more monomers and dissolves the solute polymer. The composite pressure sensitive adhesive microspheres according to claim 6, characterized in that the solvent monomer can also include one or more monomers that can not dissolve a solute polymer. The composite pressure sensitive adhesive microspheres according to claim 2, characterized in that the solute polymers comprise polymers prepared by Ziegler-Natta polymerizations, anionic polymerizations, group transfer polymerizations, ring opening polymerizations, condensation polymerizations. via free radicals and polymerization by gradual growth or the like. 9. Composite pressure sensitive adhesive microspheres according to claim 8, characterized in that the solute polymers comprise poly (acrylates), poly (methacrylates), poly (styrenes), elastomers, styrene-butadiene block copolymers, polyurethanes, polyureas, polyesters, crystalline and non-crystalline polymers, mixtures and combinations thereof. 10. Composite pressure sensitive adhesive microspheres according to claim 2, characterized in that the solvent monomer comprises (meth) acrylates, vinyl esters, styrene, acrylonitrile, mixtures thereof and the like. 11. Compound pressure-sensitive adhesive microspheres, characterized in that the microspheres are hollow, solid, or mixtures thereof. The composite pressure sensitive adhesive microspheres according to claim 2, characterized in that the microspheres are prepared by suspension polymerization of solutions of at least one solute polymer dissolved in at least one solvent monomer. 13. A suspension polymerization process for preparing composite pressure sensitive adhesive microspheres, characterized in that they comprise the steps of: (a) preparing a solute polymer; (b) dissolving the solute polymer in at least one solvent monomer to provide a solute polymer / solvent monomer mixture; (c) dissolving the initiator in the solute polymer / solvent monomer mixture; (d) charging the reaction vessel with water, a surfactant, optionally, a stabilizer and the solute polymer / solvent monomer mixture to provide a reaction mixture; and (e) stirring the reaction mixture to create an emulsion and heat the emulsion while stirring is maintained.