MXPA01005940A - Repositionable microsphere adhesive coated article - Google Patents

Abstract

An adhesive coated article comprises a layer of microsphere adhesive onto a portion of at least one major surface of a substrate. The microspheres in the adhesive are obtained as the reaction product of (a) at least one alkyl (meth)acrylate ester wherein the alkyl group contains four to about 14 carbon atoms, preferably four to about 10 carbon atoms and (b) a comonomer(s). The comonomer may be a nonpolar, ionic, polar comonomer or mixtures of such monomers. This microsphere adhesive either contains a (meth)acrylamide comonomer or a polyacrylamide material is post-added to the microsphere adhesive. The adhesive exhibits a lower than expected adhesion to coated papers without sacrificing the adhesion to standard uncoated (bond) papers and preferably, the 90°peel adhesion, as measured on Kromkote®paper (used as an industry standard) is in the range of 20 to 250 grams/inch.

Description

REPOSITIONABLE ARTICLE COATED WITH ADHESIVE MICROSPHERES Field of the Invention This invention relates to coated articles with adhesive and in particular to coated microsphere adhesives on a particularly useful substrate for coated paper.

BACKGROUND OF THE INVENTION Repositionable tags, bookmarks and labels have become an easily recognizable part of the office and the home. Repositionable tags and bookmarks, such as those manufactured by 3M under the brand name of POST-IT® Notes and POST-IT® Flags, are used to mark documents for reproduction, for easy reference, to communicate comments or questions to another reader, your favorite recipe, a much loved passage from a book and so on. These products are convenient, easy to use and easy to reposition from one portion of a document to another. REF: 129839 The coated paper or "satin" as it is sometimes called, is sometimes used in the printing of covers, magazines, sales pieces, direct mail, response cards, and brochures. The most distinctive feature of a coated paper is that the printing tapes are kept above the coating (the ink tends to seep onto an uncoated sheet of merchandise). The result is a clear and clear image. For this reason, coated papers are used when precise color matching, extremely light detail, or faithful reproduction of the photograph (both color and black and white) is desired. Although coated merchandise is generally more expensive than uncoated merchandise, it is the paper of choice for high quality printing. There are two basic categories of paper finishes that are commonly used today: the coated and the uncoated. All papers begin as uncoated, and are commonly used in this form. The anti-reflective surface of uncoated papers makes them suitable for all types of reading material, and is therefore widely used in paperback books, newspapers and the newer textbooks. Generally, the term "coated paper" refers to paper and cardboard, to which the desired surface is subjected to treatment with clay or other pigment and a mixture of adhesives. Or other suitable material, to improve the finish with respect to quality, color, smoothness, opacity or other surface properties of the print. The term also applies to lacquered and varnished papers. However, with coated papers, the repositionable adhesive that allows a repositionable label, which is raised and reused, to be used has a tendency to accumulate adhesion and form a more permanent bond between the label or marker and the adhesive. paper to which the tag or bookmark is joining. Therefore when you mark magazines or catalogs and even old textbooks (the use of coated papers) with tags or bookmarks, there is a possibility that the repositionable tag or bookmark becomes more permanently attached. This behavior is generally referred to as "adhesion buildup" and is generally not observed with uncoated papers.

Therefore, there is a need to produce a repositionable article coated with adhesive that retains the repositionability characteristic of the adhesive when used on coated papers.

Brief Description of the Invention In brief, in one aspect of this invention there is provided an adhesive coated article comprising a layer of microsphere adhesive on a portion of at least one major surface of a substrate. The microspheres in the adhesive are obtained as the reaction product of (a) at least one alkyl (meth) acrylate ester wherein the alkyl group contains from 4 to about 14 carbon atoms, preferably from 4 to preferably 10 carbon atoms. carbon and (b) comonomers. The comonomer can be non-polar, ionic, polar or mixtures such as monomers. This microbead adhesive exhibits less than expected adhesion on coated papers without sacrificing adhesion for conventional uncoated (bond) papers. Preferably, the peel adhesion of 90 °, as quantified on Kromkote® paper (used as an industrial standard) is in the range of 20 to 250 grams / 2.54 cm. Advantageously, the microsphere adhesive used in the present invention can either contain microspheres that have been formulated with a comonomer containing (meth) acrylamide ("in si tu") or a polyacrylamide material can be added to an adhesive of microspheres ("post-terior addition"), even if the microspheres do not contain a (meth) acrylamide comonomer. In another aspect of this invention, the microspheres are made as described in the patent of E. U. A. No. 3,691,140 (Silver). The resulting microspheres coagulate and re-disperse in a solvent. To this organic solvent dispersion an aqueous polyacrylamide material is added and mixed in the dispersion at a loading of 1-101 by weight. Then this material is coated on a suitable reinforcement. With this aspect of the invention other microspheres made by these methods are described in U.S. Patent Nos. 5,571,617 (Cooprifer et al.,); 5,714,237 (Cooprider et al); 5,118,750 (Plata et al); 5,045,569 (Delgado); 5,824,748 (Kesti et al); 4,786,696 (Bohnel); and 5,756,625 (Crandall et al) and can be used in combination with polyacrylamide, either in solvent or in its aqueous form, to form adhesive combinations with reduced adhesion to coated paper without sacrificing adhesion for uncoated papers (bond ). As used in this application: The term "adhesive coated article" refers to an article having at least a portion of its substrate coated with an adhesive; The term "coated paper" refers to a paper or board from which the surface has been subjected to treatment with clay or other pigment and a mixture of adhesives, or other suitable material, to improve the finish with respect to quality, color , uniformity, opacity of printing or other properties of the surface and the term also applies to lacquered or varnished papers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Useful monomers of alkyl (meth) acrylate are those esters of unsaturated and monofunctional (meth) acrylate, of which the alkyl groups have from 4 to 14 carbon atoms. These (meth) acrylates are oleophilic, dispersible in water, and essentially insoluble in water. Moreover, useful (meth) acrylates are those which, as homopolymers, generally have a vitreous transition temperature below about -20 ° C, or if a combination of monomers is used, this combination can produce a copolymer or tere -polymer that generally has a glass transition temperature below about -20 ° C. non-limiting examples of these (meth) acrylate include but are not limited to isooctyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-acrylate, 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) axcrilate monomers include isooctyl acrylate, isononyl acrylate, isoamyl acrylate, isodecyl methacrylate, 2-ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate, and mixtures thereof. Suitable vinyl ester monomers for use in the present invention include but are not limited to: vinyl 2-ethylhexanoate, vinyl caprate, vinyl laurate, vinyl pelargonate, vinyl hexanoate, vinyl propionate, vinyl decanoate, vinyl octanoate, and other unsaturated vinyl esters monofunctional linear or branched carboxylic acids comprising 1 to 14 carbon atoms, which as a homopolymer have a glass transition temperature below about -10 ° C. Preferred vinyl ester monomers include vinyl laurate, vinyl caprate, 2-ethylhexanoate vinyl, and mixtures thereof. Further vinyl monomers which, as homopolymers, have glass transition temperatures greater than about -10 ° C to 0 ° C, such as vinyl acetate, acrylonitrile, mixtures thereof and the like, can optionally be used in conjunction with one or more acrylate, methacrylate and vinyl ester monomers with the proviso that the vitreous transition temperature of the resulting polymer is below about -10 ° C. Suitable comonomers include polar, ionic, non-polar monomers and mixtures thereof. In addition to using one or more acrylate monomers in the manner of a comonomer, as described above, the following are non-limiting examples of comonomers: (1) ionic comonomers, such as sodium methacrylate, ammonium acrylate, sodium acrylate, (I) ) p-vinyl triethylamine benzimide, (II) 4, 4, 9-trimethyl-4-azonium-7-oxo-8-oxa-dec-9-ene-l-sulfonate, (III) N propionate betaine, N-dimethyl-N- (β-methacryloxyethyl) ammonium, (IV) methacrylyl of trimethylamine, (V) methacrylimide of 1,1-dimethyl-l (2,3-dihydroxypropyl) amine; and any amphoteric ion monomers and the like; (2) non-polar comonomers including but not limited to 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, isodecyl methacrylate, acrylate of t-butyl, t-butyl methacrylate, isobornyl acrylate, octyl acrylamide, methyl methacrylate, isononyl acrylate, isodecyl acrylate, styrene and the like and any combination thereof. (3) polar comonomers which may or may not contain a dissociable hydrogen. Examples of the polar comonomers include organic carboxylic acids comprising from 3 to about 12 carbon atoms and generally having from 1 to about 4 carboxylic acid moieties. Non-limiting examples of these comonomers include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, maleic acid, β-carboxyethylacrylate and the like. In addition, suitable polar comonomers include acrylamide, methacrylamide, 2-hydroxyethyl acrylate, and the like. In addition, one type of suitable comonomers are the amino functional monomers having a core or core portion of the general formula (a): ## STR3 ## where : Ri is -H, -CH3, -CH2CH3, cyano or carboxymethyl, R2 is a hydrocarbyl radical comprising from 1 to about 12 carbon atoms; R3 and R4 are independently H or an alkyl group containing from 1 to about 12 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety; L is a carbon-carbon bond, 0, NH or S; and x is an integer from 1 to 3. Non-limiting examples of the comonomers according to formula (1) include N, N-dimethyl-aminoethyl (methyl) acrylate, N, N-dimethylaminopropyl- (meth) acrylate, t-butylaminoethyl (methyl) acrylate and N, N-diethylaminoacrylate. Another class of suitable comonomers are comonomers having a core or core portion of the general formula (2): # II CH2 = CHR? -C-L-R2- (R5) xR6 (2) wherein: Ri is -H, -CH3, -CH2CH3, cyano or carboxymethyl, R2 is a hydrocarbyl radical comprising from 1 to about 12 carbon atoms; Rs is -O-, alkylene oxide comprising from 1 to 5 carbon atoms, or phenoxy oxide, wherein the alkylene oxide may include, -CH20-, -CH2CH20-, CH2 (CH) CH30-, and the like; R6 is H, -C6H4OH, or -CH3 L is a carbon-carbon bond, O, NH or S; and x is an integer with the proviso that when R5 is -0-, x is an integer of 1-3. Non-limiting examples of the comonomers according to formula (2) include hydroxyethyl (meth) acrylate, glycerol mono (meth) acrylate and 4-hydroxybutyl (meth) acrylate, poly (ethylene oxide) terminated by acrylate; the poly (ethylene oxide) terminated in methacrylate; the poly (ethylene oxide) methoxylate ethoxy; the poly (ethylene oxide) of butoxyl methacrylate; the poly (ethylene glycol) terminated in acrylate; the poly (ethylene glycol) terminated in acrylate; methoxypoly methacrylate (ethylene glycol); butoxipoli methacrylate (ethylene glycol) and mixtures thereof.

Even another class of suitable comonomers are the amido-functional monomers having the core or core portion of the general formula (3): OR II CH2 = CHR? -C-NR3R4 (3) wherein: Ri is H, IH3, ICH2CH3, cyano or carboxymethyl; and R3, R4 are independently H or an alkyl group containing from 1 to about 12 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety. Non-limiting examples of the comonomers according to formula (3) include N-vinyl pyrrolidone, N-vinyl caprolactam, acrylamide or N, N-dimethyl acrylamide. Non-limiting examples of other suitable comonomers which do not fall within the above classes but which are within the scope of the permissible comonomers include (meth) acrylonitrile, furfuryl (meth) acrylate and tetrahydrofuryl (meth) acrylate, 2-vinyl pyridine , and 4-vinyl pyridine. Typically, when a comonomer is present, the relative amounts by weight of the alkyl (meth) acrylate monomers and the comonomer are in the range of about 99.5 / 0.5 to 75/25, and preferably in the range of 98/2. to 90/10. In addition, the unsaturated vinyl additive can be used to improve stability and performance. Suitable vinyl unsaturated additives having both an ionic portion and a hydrophobic portion containing at least 5 but not more than 40 carbon atoms include: the salts of sulfoesters of alpha-methylenecarboxylic acids such as 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 2-sulfoethyl a-ethylacrylate, 2-sulfoethyl a-hexylacrylate, 2-sulfoethyl a-cyclohexylacrylate, 2-sulfoethyl a-chloroacrylate, 2-sulfo-1-propyl acrylate, 2-sulfo-1-butyl and methacrylate, 3-sulfo-2-butyl acrylate and methacrylate, 2-methyl-1-sulfo-2-propyl acrylate and methacrylate, 3-bromo-2-sulfo-1-acrylate propyl, 3-chloro-2-sulfo-1-propyl acrylate, 3-chloro-2-sulfo-1-butyl acrylate, 3-methoxy-2-sulfo-1-propyl acrylate, 2-sulfo- cyclohexyl, 2-phenyl-2-sulfoethyl acrylate, 4-sulfo-l-butyl acrylate, 6- (sulfophenoxy) hexyl acrylate and methacrylate. The preparation of these materials is described in U.S. Patent No. 3,024,221, of which the description is incorporated herein by reference. Other suitable vinyl-unsaturated additives include but are not limited to (1) salts of sulfate esters of alpha-methylenecarboxylic acids including 3-sulfate-2-hydroxy-1-propyl methacrylate, (2) salts of the esters of carboxyl-terminated alkyl of the alpha-methylenecarboxylic acids including 11-methacryloxyundecanoic acid, (3) salts of the sulfoalkylallyl ethers including the allyl ether of 3-sulfo-2-hydroxy-1-propyl, (4) salts of the acrylamide alkane sulfonates including the 2-acrylamido-2-methyl propanesulfonates, (5) salts of the alkyl vinyl phosphonate esters including the octyl vinyl phosphonates and (6) salts of the aryl vinyl sulfonates including the paraestirene sulfonates.

Typically, the unsaturated vinyl additive having both an ionic portion and a hydrophobic portion is present in relative amounts by weight of the total polymerizable content from about 0.1 to about 3 parts and preferably from about 0.5 to about 3 parts. An optional modifier can be used to regulate the portion of the soluble solvent in the microspheres and is added to the polymerization mixture in an amount sufficient to provide a portion of soluble solvent that is in the range of 30-98%, preferably in the range of 40-95%. Various modifiers can be used within the scope of this invention and the amounts used are those that sufficiently provide the microspheres with a soluble solvent portion. These amounts include, for example for solvents from 5-30%, for tackifiers and / or plasticizers from 1-30% for chain transfer agents, up to about. Particularly useful modifiers are chain transfer agents. In order to control the molecular weight of the polymer that is being formed in the microsphere, it is desirable to use a chain transfer agent or a modifier. Various organic compounds containing sulfur and halogen work well as chain transfer agents in free radical polymerizations. Non-limiting examples of these agents are: carbon tetrabromide, carbon tetrachloride, dodecanetiol, iso-octyl thioglycolate, butyl mercaptan, and tertiary dodecyl mercaptan. In this invention it is effective to employ the long chain mercaptans such as dodecanetiol. The amount of the suitable chain transfer agent for these microsphere polymerizations is calculated based on the weight of the total polymerizable content. The chain transfer agent is preferably added up to about 0.15%, more preferably up to about 0.12% and more preferably up to about 0.08%. These levels are suitable to provide a soluble polymer content in the microspheres of up to about 98%. The microsphere adhesive composition may also contain a crosslinking agent. Examples of useful crosslinking agents include, but are not limited to: multifunctional (meth) acrylates, for example, butanediol diacrylate or hexanediol diacrylate or other multifunctional crosslinking agents such as divinylbenzene and mixtures thereof. When used, the crosslinking agents are added at a level of up to about 0.15 weight percent equivalents, preferably up to about 0.1 weight percent equivalents, of the total polymerizable composition with the proviso that the combination of the crosslinking agent and the concentrations of the modifier are selected to obtain a microsphere with 30 to 98% of the soluble solvent portion. The microspheres of the present invention are prepared by suspension polymerization using either a one-step or two-step process as described in detail below. Suspension polymerization is a process in which a monomer is dispersed in a (usually aqueous) medium in which it is insoluble. The polymerization is allowed to proceed within the individual droplets of the polymer. The free radical initiators soluble in monomers are preferably those that are used. The kinetics and the mechanism are those for corresponding block polymerization under similar conditions of temperature and concentration of the initiator. The initiators that affect the polymerization are those which are normally suitable for the polymerization of free radicals of acrylate monomers. Examples of such initiators include thermoactivated initiators such as azo compounds, hydroperoxides, peroxides and the like and photo-initiators such as benzophenone, ethyl benzoin ether and 2,4-dimethoxy-2-phenyl acetophenone. Other suitable initiators include lauroyl peroxide and bis (t-butylcyclohexyl) peroxide dicarbonate. The initiator is present in a sufficient catalytically effective amount to produce a high conversion of monomers in a predetermined time span and temperature range. Typically, the initiator is present in amounts ranging from 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomer raw material. The parameters that affect the concentration of the initiator employed include the type of initiator and the monomers and / or the monomer involved in particular. It is believed that catalytically effective concentrations range from about 0.1 to about 2% by weight of the total monomers and more preferably, from about 0.2 to about 0.70% by weight of monomers and / or monomer. Optionally, a polymeric stabilizer can be used. Advantageously, the presence of the stabilizer allows the use of relatively small amounts of the surfactant while still obtaining microspheres. Any polymeric stabilizer which effectively provides sufficient stabilization of the final polymerized droplets and which prevents agglomeration within the suspension polymerization process is useful in the present invention. When used, a polymeric stabilizer is typically present in the reaction mixture in an amount by weight of from about 0.1 to about 3 parts by weight per 100 parts of the polymerizable monomer, and more preferably is present in an amount by weight of about 0.1 to about 1.5 parts by weight per 100 parts of the polymerizable monomer. Exemplary polymeric stabilizers include polyacrylic acid salts of more than 5,000 molecular weight average (e.g., ammonia, sodium, lithium and potassium salts), carboxyl-modified polyacrylamides (e.g., Cyanamer ™ A-370 from American Cyanamid), copolymers of acrylic acid and dimethylaminoethyl methacrylate and the like, quaternary polymeric amines (e.g., General Analine and Film's Gafquat ™ 755, a quaternized copolymer of polyvinylpyrrolidone, or Union Carbide "JR-400", a quaternized substituted amine cellulosic ), cellulosics, and carboxyl-modified cellulosics (eg, Hercules Natrosol ™ CMC Type 71, sodium carboxymethylcellulose).

Surfactants are typically present in the reaction mixture in an amount of not more than about 5 parts by weight per 100 parts by weight of the polymerizable monomer, preferably not more than about 3 parts by weight, and more preferably in the range of 0.5 to 1.5 parts by weight per 100 parts by weight of the polymerizable monomer. Useful surfactants include anionic, cationic, nonionic or amphoteric surfactants, including but not limited to anionic surfactants, such as arylalkyl sulfonates, for example, sodium dodecylbenzene sulfonate and sodium decylbenzene, sodium and ammonia salts. or alkyl sulfates, for example sodium lauryl sulfate, and ammonium lauryl sulfate; nonionic surfactants, such as ethoxylated oleoyl alcohol and polyoxyethylene octylphenyl ether; and cationic surfactants, such as a mixture of the alkyldimethylbenzyl 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, the sulfobetaines, N-alkylaminopropionic acid, and the N-albetataines. To initiate the polymerization reaction, a sufficient amount of free radicals must be present. This can be achieved by various methods that are well known in the art, such as thermal initiation or free radical radiation. For example, heat or radiation can be applied to initiate the polymerization process of the monomers, which is an exothermic reaction. However, it is preferred to apply heat until the thermal decomposition of the initiators generates a sufficient amount of free radicals to begin the reaction. The temperature at which this occurs varies greatly depending on the initiator used. In addition, deoxygenation of the polymerization reaction mixture is commonly desirable. It is well known that dissolved oxygen in the reaction mixture can inhibit polymerization and it is desirable to expel this dissolved oxygen. Although, an inert gas bubbling into the reaction vessel or through the reaction mixture is an effective oxygenation medium, other deoxygenation techniques that are compatible with the polymerization suspension can also be used. Typically, nitrogen is used to deoxygenate, although any inert gas from Group VIIIA (CAS version) is also suitable. Although the specific parameters of agitation time and speed are dependent on the monomers, and initiators, it is desirable to previously disperse the reaction mixture until the reaction mixture reaches a state where the average monomer droplet size is between about 1. μm and 300 μm and preferably between 20 μm and 70 μm. The average particle size tends to decrease by increased and prolonged agitation of the reaction mixture. Preferably, agitation and nitrogen purge are maintained throughout the reaction period. Initiation begins by heating the reaction mixture. After polymerization, the reaction mixture is cooled. In a one step process both the alkyl methyl (meth) acrylate monomer and any optional comonomer are present together in the suspension at the beginning of the polymerization. In a two-step process, any optional comonomer is typically added after the initial exotherm which results from the polymerization has begun. The other components, such as the initiator, stabilizers (if used), surfactants and modifiers are present in the reaction mixture as described in the above processing steps. After polymerization, a suitable aqueous suspension of microspheres at room temperature can be obtained. The suspension can have non-volatile contents of solids from about 10 to about 70% by weight. After a prolonged time of staying motionless, the suspension is typically separated into two phases, one phase is aqueous, and essentially one phase of microsphere-free polymer and the other phase is an aqueous suspension of the polymeric microspheres, that is, the phase rich in microspheres. The aqueous suspension of microspheres can be used immediately after the polymerization, because the suspension of microspheres of the present invention is particularly stable to agglomeration or coagulation. Advantageously, the microspheres of the present invention can be easily coated from an aqueous solution. Surprisingly, the microspheres of the present invention are very well suited to conventional coating techniques having intensified fluid processing characteristics. The microsphere rich phase can be diluted with an additional amount of water or solvent, or redispersed by stirring or other agitation means. Generally, this aqueous suspension can be coated onto a reinforcement or other substrate that is employed when using conventional coating methods, such as slot die coating, to provide an adhesive coating. The microspheres can be compounded with various rheology modifiers and / or latex adhesives or "binders". Typically, the adhesive coating which, when dried, exhibits a dry coating weight in the range of 2 to about 25 grams per square meter to provide a sheet material coated with adhesive wherein the adhesive coating comprises the polymeric microspheres , the polymeric stabilizer, the surfactant agent, and optionally the rheology modifiers, and / or the latex adhesives. Alternatively, the microspheres are coagulated by the use of coagulation agents such as isopropanol, methanol, saturated solutions of salt, or the like. The coagulating agent is isolated and redispersed by stirring in a suitable organic solvent, for example n-heptane. A coating can then be made from the dispersion of the organic solvent. In another aspect of the present invention the microspheres are made as described in the patent of E. U. A. No. 3,691,140. The resulting microspheres coagulate and re-disperse in solvent. To this organic solvent dispersion is added an aqueous polyacrylamide material and the dispersion is mixed at a loading of 1-10% by weight. Then this material is coated in a suitable reinforcement. With this aspect of the invention, microspheres made by these methods are described in U.S. Patent Nos. 5,571,617 (Cooprifer et al.,); 5,714,237 (Cooprider et al); 5,118,750 (Plata et al); 5,045,569 (Delgado); 5,824,748 (Kesti et al); 4,786,696 (Bohnel); and 5,756,625 (Crandall et al), and these descriptions are incorporated herein. These microspheres can be used in combination with the polyacrylamide, either in solvent or in aqueous form, to form adhesive combinations with less adhesion to the coated paper without sacrificing adhesion on uncoated papers. The properties of the pressure sensitive adhesives of the present invention can be altered by the addition of resins to increase the viscosity and / or plasticizing agents after pollination. Preferred viscosity agents and / or plasticizers that can be used herein include hydrogenated resin esters commercially available from such companies as Hercules, Inc. under the trade names of Foral ™, Regalrez® and Pentalyn ™. Resins for increasing viscosity also include those based on t-butyl styrene. Useful plasticizers include but are not limited to dioctyl phthalate, 2-ethylhexyl phosphate, tricresyl phosphate, and the like. If these viscosity agents and / or plasticizers are used, the amounts used in the adhesive mixture are effective amounts for the known uses of these additives. Optionally, adjuvants, such as rheology modifiers, dyes, fillers, stabilizers, pressure-sensitive latex agglutinators and various different polymeric additives can be used. If such adjuvants are used, the amounts used in the adhesive mixture are effective amounts for the known uses of these adjuvants. The reinforcements that are used as substrates for the adhesive articles can be materials that are conventionally used as tape reinforcements can not be of another flexible material. These reinforcements include, but are not limited to, those that are made from materials selected from the group consisting of poly (propylene), poly (ethylene), poly (vinyl chloride), polyester (e.g., poly (ethylene terephthalate). ), such as those available under the tradename of 3M "Scotch" 8050 film), polyamide films such as those available from DuPont Co., under the tradename "KAPTON," cellulose acetate, and ethylcellulose.

The reinforcements may also be woven fabric in the form of strands of synthetic or natural materials such as cotton, nylon, rayon, glass, or ceramic material, or may be of non-woven textiles such as non-woven fabric of natural or synthetic fibers or blends of this. In addition, the reinforcement may be formed of materials selected from the group consisting of metal, metallized polymeric film and ceramic sheet material. Papers that are either coated or uncoated can also be used as reinforcement in construction. These preferred materials include, but are not limited to, papers whether coated or uncoated, plastics such as polyethylene, polypropylene, polyesters, cellulose acetate, polyvinyl chloride, and poly (vinylidene fluoride), as well as paper or paper. other substrates coated or laminated with such plastics. These papers coated with thermoplastic films are commonly siliconized or otherwise subjected to treatment to confer improved release characteristics. One or both sides of the reinforcements or linings may have such release characteristics. Generally, the reinforcement or the substrate material is from about 50 μm to about 155 μm in thickness, although reinforcements or thicker or thinner substrate materials are not excluded. The adhesive coated article may further comprise a coating with a low adhesion load on at least a portion of the second main surface, such that the low adhesion load coat is placed directly under the layer of microsphere adhesive on the first main surface, such that when at least two adhesive coated articles are placed in a stack, the microsphere adhesive layer of an adhesive coated article is placed adjacently on the coating with the low adhesion filler of the adhesive. a second article coated with adhesive. Coatings with low adhesion loading are well known in the art and are generally selected to be compatible with the adhesive formulations to provide peel adhesion in the range of about 40 grams / 2.54 cm.

Descriptions of these coatings with low adhesion loading are found in Handbook of Pressure Sensitive Adhesive Technology, Second Edition, Edited by D. Satas, 1989. Particularly useful articles that are prepared by using the adhesive microspheres of the present invention include adhesive products repositionable such as repositionable paper products and markers, repositionable adhesive tape and tape markers, easel sheets, transfer sheets and tapes, signatures, repositionable glue sticks and the like, but may also include other non-repositionable commercial and industrial adhesive medical products . The present invention is further illustrated by the following examples, of the materials and particular amounts thereof which are listed in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. All materials are commercially available or are known to those skilled in the art unless otherwise indicated or apparent. The following examples are illustrative in nature and are not intended to limit the invention in any way. All percentages named in the following Tables are calculated on a weight basis for the total monomer and the content of the unsaturated vinyl additive.

Examples Analysis Methods Solvent Soluble Polymer Content: To determine the solvent soluble content of the prepared microspheres, the following process is used. One gram of the microsphere water suspension is dried in a vacuum oven without heat. After drying, 100 ml of n-heptane are added and stirred for 24 hours. After being stirred, the dispersion is poured through a filter paper (30 micrometer pores) to remove the insoluble content. The filtered product is then dried in an oven at 38 ° C. The weight of the dry filtrate divided by the dried suspension of microspheres is the% soluble polymer content of the solvent. The analysis is repeated and the data is reported as the average number of trials.

Bond Adhesion to Bond Paper (Non-Resurfaced Paper): Peel adhesion is the force required to remove an adhesive-coated sheet from a bond paper substrate at a specific angle and the rate of release. In the examples, this force is expressed in grams per 2.54 cm (grams / 2.54 cm) of sheet width coated with adhesives. The procedure followed is: A strip, 2.54 cm wide, of a sheet coated with adhesives is applied to the horizontal surface of bond paper of 9.1 kilograms (21.8 cm x 28.2 cm). A 2.04 kilogram hard rubber roller is used to firmly apply the strip to bond paper. The free end of the coated sheet is attached to the load cell of the adhesion analyzer in such a way that the release angle is 90 °. The analysis plate is then held in the jaw jaws of the tensile analysis apparatus which is capable of moving the plate away from the load cell at a constant speed of 30.8 cm per minute. A reading of the load cell in grams per 2.54 cm of the coated sheet is recorded. The samples are analyzed three times. The average value of the three analyzes is also recorded.

Adhesion to Release on Coated Paper Peel adhesion is the force required to remove a coated sheet from a coated paper substrate at a specific angle and at a release rate. The coated paper that is used is commercially available as Kromkote ™ paper and is used as the standard when comparing various formulations of the present invention Except as noted in the Examples, all references for adhesion for paper release Coated are for Kromkote ™ paper In the examples, this force is expressed in grams per 2.54 cm of the coated sheet The following procedure is: A strip, 2.54 cm wide, of the sheet coated with adhesive is applied to the horizontal surface of the coated paper of 9.1 kilograms (21.8 cm X 28.2 cm) A hard rubber roller of 2.04 kilograms is used to firmly apply the strip to the coated paper The rolled product is cured in an environment at 21 ° C / 80% relative humidity for three days The free end of the coated sheet is attached to the load cell of the adhesion analyzer in such a way that the release angle is 90 °. Analysis plate is then pressed into the jagged jaws of the tensile analysis apparatus capable of moving the plate away from the load cell at a constant speed of 30.8 cm per minute. A reading in the load cell in grams per 2.54 cm of the coated sheet is recorded. The samples are analyzed three times. The average value of the three analyzes is also recorded.

EXAMPLE 1 To a two-neck, three-necked flask equipped with a mechanical thermometer stirrer and a nitrogen inlet tube is charged with 602.75 grams of deionized water, 17.5 grams of a 10% solids solution of Stepanol AMV (name commercially available from a solution of 28% solids of ammonium lauryl sulfate commercially available from Stepan Company), 35.0 grams of a 10% solids solution of Goodrite K702 (trade name for a solution of solids at 25% polyacrylic acid, weight of average molecular weight of 240,000, commercially available from BF Goodrich Company) which has been neutralized to a pH of 7.0 with concentrated ammonium hydroxide, 7.00 grams of acrylamide and 3.50 grams of acrylic acid. This solution is mixed at 150 rpm until it is uniform and purged with nitrogen. The stirring speed is set at 380 revolutions per minute (RPM). To the above solution is added a mixed solution of 339.5 grams of isooctyl acrylate, 0.11 grams of dodecanetiol and 1.05 grams of Perkadox 16N (trade name for a 95% active initiator of commercially available bis (4-tert-butylcyclohexyl) peroxydicarbonate) of 7? KZO Chemicals Inc.). The reaction mixture is heated to 50 ° C. The agitation, and the nitrogen purge are maintained during the reaction period. The reaction is initially set at 50 ° C and exothermed after a few minutes and maintained at a maximum temperature of 77 ° C. The batch is kept at 50 ° C for 22 hours, cooled and filtered through gauze. The weight of the clot that is collected in the gauze is quantified and recorded as the% clot by weight to the monomer (0.37%). The particle size is 57μm and the level of the soluble solvent is 18%.

Examples 2-4 The reaction process as described in Example 1 is repeated for examples 2-4 with increased levels of acrylamide monomer being added. See Table 1 below.

Table 1 Example IOA AcM Value% of% Size of (grams) (grams) Maximum of Clot Content Particle Temperature of (μm (° C) Solvent Soluble 2 332.5 14.0 75 0.07 27 50 3 325.5 21.0 75 0.1 22 57 4 318.5 28.0 74 0.05 18 61 Comparative Example Cl The reaction process as described in Example 1 is repeated except that the acrylamide monomer is not added. See Table 2 below.

Table 2 Example IOA AcM Value% of% Size of (grams) (grams) Maximum Clot Content Particle of the < μm) Tempera Solvent Soluble (° C) C-1 346.5 0 76 0.25 44 88 The above examples are coated on paper at a coating weight of approximately 5.06 grams / meter square and dry at 107 ° C. The resulting coatings are analyzed for adhesion to the bond paper and its adhesion to the coated paper as described in the above analysis methods. The results are recorded in Table 3 below.

Table 3 Example% Adhesion to Adhesion to Acrylamide Bond Paper Kromkote® paper (grams / 2.54 (grams / 2.54 cm) sm) 45 230 2 4 51 212 3 6 46 187 4 8 37 156 C-1 0 71 288 Example 5 To a five-liter, three-necked flask equipped with a mechanical stirrer and thermometer and a nitrogen inlet tube is charged with 2169.9 grams of deionized water, 63.0 grams of a 10% solids solution of Stepanol AMV (trade name) for a solution of 28% solids of ammonium lauryl sulfate commercially available from Stepan Company), 126.0 grams of a 10% solids solution of Goodrite K702 (trade name for a solids solution of 25% polyacrylic acid, weight of average molecular weight of 240,000, commercially available from BF Goodrich Company) which has been neutralized to a pH of 7.0 with concentrated ammonium hydroxide, 75.6 grams of acrylamide and 12.6 grams of acrylic acid. This solution is mixed at 200 rpm until it is uniform and purged with nitrogen. The stirring speed is set at 410 revolutions per minute (RPM). To the above solution is added a mixed solution of 1171.8 grams of isooctyl acrylate, 0.50 grams of dodecanetiol and 3.78 grams of Perkadox 16N (trade name for a 95% active initiator of bis (4-tert-butylcyclohexyl) peroxydicarbonate) commercially available from AKZO Chemicals Inc.). The reaction mixture is heated to 50 ° C. Agitation, and nitrogen purge are maintained throughout the reaction period. The reaction is initially set at 50 ° C and an exotherm is made after a few minutes and maintained at a maximum temperature of 81 ° C. The batch is kept at 50 ° C for 22 hours, cooled and filtered through gauze. The weight of the clot that is collected in the gauze is quantified and recorded as the% of the clot by weight for the monomer (0.33%). The particle size is 48 μm and the level of the soluble solvent is 22%. The suspension is coagulated by the addition of a coagulating agent, pressed to dryness, and then dispersed in a heptane / isopropanol (95/5) solvent at 8.4% solids. These microspheres dispersed in the solvent are then coated on a paper by using a 100 μm fixed bar coating apparatus, dried in an oven at 104 ° C (to be dried) and analyzed for adhesion. The adhesion on the coated paper is 137.1 grams / 2.54 cm.

Examples 6-9 and Comparative Example C2 A sample of adhesive microspheres is prepared as described in the Patent of US Pat. No. 3,691,140 when using a ratio of isooctyl acrylate to ammonium acrylate of 97.6 / 2.4. The particle size is 38 μm and the level of the soluble solvent is 20%. The suspension is coagulated and redispersed in n-heptane at a solids content of 9%. To this solvent dispersion are added amounts of aqueous polyacrylamide in the amount listed (on a weight-to-weight basis) in Table 4. The samples are coated on a polyester film by using a 75 μm fixed bar coater. The coatings are dried at 66 ° C for 15 minutes. Example% of 1Weight Adhesion to Adhesion to Polyacri Molecular of bond paper lick paper Polyacrylamide (grams / 2.54 Kromkote® cm) (grams / 2.54 c) 6 0.8 10,000 16 97 7 0.4 10,000 31 136 0.8 1500 22 102 1.6 1500 13 80 C2 0 NA 60 267 1Polyacrylamide (50% aqueous solution): Aldrich Chemical Company Milwaukee, Wl 53233 Examples 10-11 When using the same formulation as ST described in Example 6, the coatings are made to a thickness of bar coating 50 μm and 100 μm. The Coatings are dried at 66 ° C for 15 minutes. The results appear in Table 5 below.

Table 5 Example Adhesion Adhesion to Adhesion to Coating paper bond paper (mils) (grams / 2.54 sm) Kromkote® (grams / 2.54 cm) 10 15 108 11 29 165 Comparative Example 12 Various commercially available repositionable adhesive-coated notes are analyzed according to the methods of analysis described above. Union Adhesion (grams / 2.54 cm) and Adhesion to Coated Paper (grams / 2.54 cm) is quantified and the results are summarized in Table 6.

Table 6 Adhesion to Adhesion to Transfer the Union Paper to Paper (grams / 2.5 Kromkote® Kromkote® 4 cm) (grams / 2.54 (grams / 2.54 cm) cm) Beautone 40.0 437.4 Yes (something) Labels that 257.8 895.8 Yes (a lot) sticks Janel Memo Tip Rediform Note 45.6 657.2 Yes (a lot) Stix Highland ™ # 45.8 375.0 Yes (slight! 6549 Notes Post- 72.0 391.6 Yes (slight! It® Notes Esselte 37.2 572.4 Yes (somewhat ) Contact Notes 62.8 377.2 Yes (slight; Adheribles Pronoti Notes 143.0 559.4 Yes (a lot) Addable Converex Example 1 45.0 230.0 No Comparative Example 13 Various commercially available repositionable adhesive coated notes are analyzed according to the methods of analysis described above. The adhesion to the detachment to the coated cardboard merchandise in these examples is quantified by using the same procedure as described in the analysis method "Adherence to the Release of Coated Paper". The results are summarized in Table 7.

Table 7 Adhesion to Adherence to Adherence to Elk Cover Master Print Reinforcement of II (grams / 2. (grams / 2.54 Merchandise 54 cm) cm) (grams / 2.54 sm) Beautone 94.4 99.? ' 126.0 TAG_204_.8 252.5 318.5D Adhesive Janel Memo Tip Rediform Note 93.8 105.6 156.0 Stix Highland ™ # 84.1 94.1 141.5 6549 Notes Post- 114.4 127.5 151.8 it® Notes Esselte 91.8 124.1 143.9 Contact Notes 84.9 109.4 118.3 Adheribles Pronoti Notes 119.4 * 187.6 * 210.5 * Adhesibles Converex * Adhesive coating that is transfd to the three re covered cardboard merchandise. D Adhesive coating that exhibits a slight transfer of adhesive to the Reinforcement in Stock.

Various modifications and alterations of this invention will become 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 is not to be unduly limited to the illustrative embodiments set forth above. All publications and patents are incorporated herein for reference to the same extent as if each publication or individual patent was specifically and individually indicated to be incorporated for reference. It is noted that in relation to this date, the best known method for the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (15)

RE GVINDI CACIONES Having described the invention as above, the content of the following claims is claimed as property:

1. An adhesive coated article comprising a substrate with a first and second main surface and a layer of microsphere adhesive on at least a portion of the first major surface of the substrate, characterized in that the microspheres of the microsphere adhesive are the reaction product of (a) at least one alkyl (meth) acrylate ester wherein the alkyl group contains from 4 to about 14 carbon atoms and (b) at least one comonomer or mixtures of these comonomers.

2. The adhesive coated article according to claim 1, characterized in that the component (b) is the (meth) acrylamide monomer.

3. An article coated with an adhesive characterized in that it comprises a substrate with a first and second main surface and a layer of microsphere adhesive in at least a portion of the first major surface of the substrate, wherein the microspheres of the microsphere adhesive are the product of (a) at least one alkyl (meth) acrylate ester wherein the alkyl group contains from 4 to about 14 carbon atoms and (b) a (meth) acrylamide monomer with the proviso that the microspheres is not a stabilized microsphere adhesive composition comprising: (i) a variety of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of reactants comprising polymerizable feedstock comprising at least one C4-C ?4 (meth) acrylate monomer and optionally at least a comonomer, at least one of the comonomers is (meth) acrylamide, (ii) at least one unsaturated vinyl additive having both an ionic portion and a hydrophobic portion and containing at least 5 but not more than 40 carbon in an amount of about 0.1 to 3 parts by weight of the microspheres. (iii) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the microspheres; (iv) an initiator in an amount effective to catalyze the polymerization reaction present in amounts ranging from about 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomer raw material.

4. The article coated with adhesive according to claim 2, characterized in that the microsphere adhesive further includes 1-10% by weight of an aqueous polyacrylamide material.

5. The adhesive coated article according to claims 1 to 4, characterized in that the microsphere adhesive has a 90 ° release value, as quantified on Kromkote® paper in the range of 20 to 250 grams / 2.54 cm.

6. The adhesive coated article according to claim 3, characterized in that the microsphere adhesive comprises (a) a plurality of polymeric, solid, elastomeric microspheres which are the reaction product of reactants comprising polymerizable raw material comprising at least C4-C14 alkyl (meth) acrylate ester monomers and at least one (meth) acrylamide comonomer with the proviso that the (meth) acrylamide comonomer does not have a dissociable proton having a Kd of more than 10"3 , (b) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of microspheres, and (c) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of microspheres selected from the group consisting of non-polar, ionic and polar comonomers.

7. The article coated with adhesive according to claim 1, characterized in that the microsphere adhesive comprises (a) a variety of polymeric microspheres, solid, and elastomeric which are the reaction product of the reagents comprising polymerizable raw material comprising at least one monomer of C4-C14 alkyl ester (meth) acrylate and at least one polar comonomer with the proviso that the polar comonomer has a dissociable proton, the polar comonomer does not have a dissociable proton having a Kd greater than 10"3, (b) a polymeric stabilizer in an amount of about 0.1 to about 3 parts by weight per 100 parts by weight of microspheres, and (c) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of microspheres.

8. The adhesive coated article according to claim 3, characterized in that the microsphere adhesive comprises (a) a plurality of polymeric and elastomeric microspheres wherein the microspheres are the reaction product of the polymerizable raw material comprising at least one monomer of C4-C14 alkyl ester (meth) acrylate and at least one (meth) acrylamide comonomer, (b) an initiator for the polymerizable monomer raw material which is present in amounts ranging from 0.1 to about 2 parts by weight weight per 100 parts by weight of the polymerizable monomer raw material, (c) optionally, a polymeric stabilizer in an amount ranging from about 0.1 to about 3 parts by weight per 100 parts by weight of the microspheres, (d) an agent surfactant in an amount not greater than about 5 parts by weight per 100 parts by weight of the microspheres, and (e) an agent of chain transfer in an amount sufficient to produce 30-98% of a portion of the soluble solvent in the microspheres.

9. The adhesive coated article according to claim 1, characterized in that the microsphere adhesive comprises (a) a plurality of polymeric and elastomeric microspheres wherein the microspheres are the reaction product of the polymerizable raw material comprising at least one monomer of C4-C14 alkyl ester (meth) acrylate, (b) an initiator for the polymerizable monomer raw material present in amounts ranging from 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomer raw material, (c) optionally, a polymeric stabilizer in an amount ranging from about 0.1 to about 3 parts by weight per 100 parts by weight of the microspheres, (d) a surfactant in an amount not greater than about 5 parts by weight per 100. parts by weight of the microspheres, and (e) a chain transfer agent in an amount sufficient to produce -98% in a portion of the soluble solvent in the microspheres.

10. The article coated with adhesive according to claim 9, characterized in that it also comprises (f) at least one vinyl-unsaturated additive having both an ionic portion and a hydrophobic portion containing at least 5 but not more than 40 carbon atoms in an amount ranging from about 0.1 to 3 parts by weight of the microspheres

11. The adhesive coated article according to claim 3, characterized in that the microsphere adhesive comprises a variety of hollow, polymeric, acrylate, inherently sticky, infusible, solvent insoluble, solvent dispersible, pressure sensitive microspheres comprising ( a) at least about 85 parts by weight of at least one alkyl acrylate ester or an alkyl (meth) acrylate ester, and (b) up to about 15 parts by weight of at least one (meth) acrylamide monomer, wherein a majority of the microspheres contain at least one interior void space having a diameter of at least about 10% of the diameter of the hollow microspheres.

12. The adhesive coated article according to claim 1, characterized in that the microsphere adhesive comprises a variety of hollow, polymeric, acrylate, inherently sticky, infusible, solvent insoluble, solvent dispersible, pressure sensitive microspheres comprising ( a) at least about 85 parts by weight of at least one alkyl acrylate ester or an alkyl (meth) acrylate ester, and (b) up to about 15 parts by weight of at least one polar monomer, wherein most of the microspheres contain at least one interior void space having a diameter of at least 10% of the diameter of the hollow microspheres.

13. The article coated with adhesive according to claim 1, characterized in that the microsphere adhesive comprises microspheres composed of a pressure sensitive adhesive comprising a mixture of two or more water-insoluble polymers that are fully present within the limits of the microspheres, wherein at least one water insoluble polymer is a polymer solute and at least one water insoluble polymer is the polymer matrix.

14. The adhesive-coated article according to claim 1 or 3, characterized in that the microsphere adhesive comprises microspheres composed of a pressure-sensitive adhesive comprising a mixture of two or more water-insoluble polymers that are fully present within the limits of the microspheres, wherein at least one water insoluble polymer is a polymer solute and at least one water insoluble polymer is a polymer matrix, and wherein the polymer solute is a homopolyme or a copolymer that is prepared from (meth) acrylamide monomers.

15. The article coated with adhesive according to claim 1 or 3, characterized in that it also comprises a coating with low adhesive loading that is placed directly under the layer of adhesive microspheres on the first main surface, such that when at least two Adhesive-coated articles are stacked one on another, the adhesive microsphere layer of the first adhesive-coated article is adjoiningly placed on the low-adhesive coating of the second adhesive-coated article.