MXPA99003243A - Stabilized adhesive microspheres - Google Patents

Abstract

Stabilized microsphere adhesive composition comprising:a plurality of polymeric, elastomeric microspheres wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one C4-C14alkyl(meth)acrylate monomer and optionally at least one comonomer, at least one vinyl-unsaturated additive having both an ionic moiety and a hydrophobic moiety and containing at least 5 but not more than 40 carbon atoms in an amount about 0.1 to 3 parts by weight of the microspheres;optionally, a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres;a surfactant in an amount of no greater than about 5 parts by weight per 100 parts by weight of the microspheres;optionallya modifier, wherein the modifier is at least one of a chain transfer agent, a tackifier, a solvent or the like in an amount that is sufficient to provide microspheres with a n-heptane soluble portion in the range of 30-98%;and (f) an initiator in an amount effective to catalyze the polymerization reaction present in amounts ranging from about 0.1 to approximately 2 parts by weight per 100 parts by weight of the polymerizable monomer starting material.

Description

STABILIZED ADHESIVE MICROSPHERES FIELD OF THE INVENTION This invention relates to a composition of suspension polymerized adhesive microspheres, and in particular to adhesive microspheres that exhibit improved adhesion to substrates, while remaining reclosable and more stable during polymerization and processing.

BACKGROUND OF THE INVENTION The inherently sticky elastomeric microspheres are known in the art as useful in reclosable, pressure sensitive adhesive applications. As used herein, the term "recolocable" refers to the ability to be repeatedly adhered and removed from a substrate without substantial loss of adhesion capacity. Repositionable adhesives are used in the construction of messaging or temporary signage for the domestic environment and ref. 29859 office. An example of such products are the Post-it® self-adhesive notes sold by 3M Company. Numerous references refer to the preparation and / or the use of acrylate, elastomeric, inherently sticky polymeric microspheres, which are solid in nature. Such spheres and their use in aerosol adhesive systems having reclosable properties are described in US Pat. No. 5,215,818. These. microspheres are prepared by the polymerization by aqueous suspension of alkyl acrylate monomers and ionic comonomers, for example, sodium methacrylate, in the presence of an emulsifier, preferably an anionic emulsifier. The ionic comonomers other than the aforementioned acrylates are specifically amphoteric in nature and do not show that they improve the stability of the suspension or operation of the same. U.S. Patent No. 4,166,152 discloses the inherently sticky solid (meth) acrylate microspheres which are prepared from non-ionic methacrylate or alkyl acrylate monomer (s) in the presence of an emulsifier and an ionic suspension stabilizer having a sufficient interfacial tension to prevent agglomeration of the microspheres. Such microspheres are also described in U.S. Patent Nos. 4,495,318 and 4,598,112, where the preparative methods involve the use of a nonionic emulsifier or a cationic emulsifier. All three patents describe the utility as a "reusable adhesive". The increase in adhesion of these types of adhesives has been addressed by various investigators: in US Patent No. 5,053,436 it provides a hollow core in the microsphere. In this morphology it is said that the microspheres offer increased resistance to the transfer of the adhesive and an increased level of adhesion due to the hollow nature of the microsphere. U.S. Patent No. 4,988,567 describes microspheres that have multiple small empty spaces. These empty spaces are said to improve the adhesive properties of the microsphere. It is said that the described microspheres are insoluble in solvent. US Patent No. 4,786,696 discloses a suspension polymerization process for preparing inherently sticky (meth) acrylate microspheres, solid, which do not require the use of either an ionic comonomer or an ionic suspension stabilizer, in order to prevent the agglomeration Rather, the process requires agitation of the container charge before the start of the reaction, sufficient to create a suspension of droplets of monomers having an average monomer droplet size of about 5 and about 70 microns. In addition to the (meth) acrylate monomer, a minor portion of a nonionic vinyl comonomer, such as for example acrylic acid may be included to modify the "sticky nature" of the microspheres. The resulting adhesive microspheres show high tack values that are thought to be due to the lack of stabilizer on the surface of the microsphere. The American Patent No. 3, 620,988 discloses a method for preparing "sphere-type polymers" which involves the use of a polymeric, insoluble, water-thickening dispersion agent. The method can be applied to produce pressure sensitive adhesives in the form of suspensions of coatable spheres. The adhesives comprise a suspension / dispersion with high solids content of a lightly cross-linked polymer of a higher alkyl acrylate and a thickener. U.S. Patent No. 4,735,837 discloses a detachable adhesive sheet having an adhesive layer containing "elastic microbeads", wherein the microbeads project partially from the surface of the adhesive layer. The microbeads may or may not be sticky. These can be derived from, for example, (meth) acrylate monomer and an α-olefinic carboxylic acid monomer by means of polymerization and suspension in an aqueous medium. However, details regarding the nature of the surfactants used, etc. are not described. The microbeads and an adhesive are dispersed in solvent, mixed and coated, with the ratio of adhesive to the microbeads that is from about 1:10 to about 10: 1. This ratio is described as critical in order that all microbeads in the final product, including those that project from the surface, are completely covered with the adhesive. It is described that a range of 1,000 to 150,000 pieces per square centimeter is preferred. German Patent No. 3,544,882 A1 discloses crosslinked microspheres composed of 90 to 99.5 weight percent of (meth) acrylate ester and 10 to 0.5 weight percent of vinyl monomer, for example, acrylic acid, which has a group reactive functional through which cross-linking is achieved by reaction with an oil-soluble crosslinking agent. The microspheres are prepared by dispersing in water a solution (in organic solvent) of copolymer prepared by known methods such as solution, bulk, emulsion or suspension polymerization. (However, the reference notes that in cases where the emulsion or suspension polymerization is used with water as a dispersion medium, it is not necessary to make a new aqueous dispersion.) When they are sticky, the spheres are said to be useful. in the form of sheet covered by sprinkling as "removable adhesive". The stated purpose of the invention is to provide microspheres having a uniform particle size, but it is also established that the microspheres can have other monomers such as vinyl acetate, styrene, acrylonitrile, methacrylonitrile, etc. "... to prevent partial transfer of the adhesive when the carrier is pulled from the substrate ...".

U.S. Patent Nos. 4,645,783 and 4,656,218 describe a "repeatedly usable and releasable sheet" coated with an aqueous suspension of microspheres obtained by the polymerization in aqueous suspension (in the presence of a protective colloid comprising casein as a main ingredient) of one or more esters of alkyl (meth) acrylate, α-monoolefin-carboxylic acids, and one or more other vinyl monomers. The microspheres are preferably interspersed with finer polymer particles, prepared by polymerization of one or more vinyl monomers in an aqueous medium. These fine polymer particles are said to be "... effective in improving anchoring to the adherend and adhesion to the substrate after it is applied to the substrate, the aqueous suspension prepared in accordance with the present innovation". U.S. Patent No. 3,857,731 and the European Patent No. 209337 both address problems with the transfer of adhesive microspheres. The first describes sheets coated with sticky, elastomeric polymer microspheres of the Silver patent (US Patent No. 3,691,140) and a binder material which provides plugs in which the microspheres are maintained by predominantly mechanical forces. The second states that the adhesive microspheres could be placed for more demanding applications if the disadvantage of the transfer of the adhesive did not exist. The sticky elastomeric microspheres are then described, which have a composition formed from nonionic monomers alone or together with a proportion of ionic comonomers wherein the ionic monomers are first dissolved in an organic cosolvent. The microspheres further comprise an adhesion promoting monomer having a functional group that remains unreacted during the polymerization of the monomers and is available for subsequent binding of the microspheres through electrostatic interaction or chemical bonding to a coated substrate or substrate. with binder. Preferably, the microspheres are derived from at least one alkyl acrylate or methacrylate ester. U.S. Patent No. 5,326,842 discloses the use of a dual polymerization process comprising first a suspension polymerization process, followed by an emulsion polymerization. This dual polymerization allows coatings with low or high tack to be prepared. For coatings with high tack a chain transfer agent is used in the suspension step, the subsequent emulsion polymerization provides the stability of the final material. In U.S. Patent No. 4,952,650, the polymerization of large size non-sticky spheres, which are subsequently extruded in the form of permanent film adhesives, is described. In this description, the styrenesulfonic acid or the sodium salt thereof is in a general listing of monomers, however, it is not used in the examples or is said to provide new properties of the material. Other researchers have prepared polyacrylate spheres for use in microporous sorbents as binding agents. A polyacrylate polymer product comprising (a) a suspension stabilizer modifier having a metal cation and (b) an acrylic ester copolymer of a non-tertiary alcohol having from 1 to 14 carbon atoms, a polar monomer , and at least one of the following: higher vinyl ester, styrenesulfonate salt, multivinyl monomer, and a poly (alkyleneoxy) α, β-ethylenically unsaturated, are exemplified. The use of suspension stabilizers such as zinc oxide and colloidal silica, as described, is known to suppress the adhesion characteristics of the resulting polymer. In addition, very high levels (approximately 5.5% by weight of the monomer) of the surfactant and styrene sulfonate salt are used. Again, such excessive levels are harmful to the adhesion characteristics, and could limit the utility of these polymeric spheres as relocatable adhesives. It has now been discovered that microspheres containing unsaturated vinyl additives with an ionic and a hydrophobic ratio, improve stability and performance properties, while maintaining inherent tackiness, elastomeric properties and dispersibility in solvent or water.

BRIEF DESCRIPTION OF THE INVENTION Advantageously, the present invention provides an adhesive of microspheres that improve adhesion by avoiding surface contaminants of the microspheres, without changing the physical morphology of the microsphere, or by copolymerization of a secondary polymer reaction. Uniquely, the microspheres of the present invention are prepared with the use of ionic specialty monomers that serve not only as a stabilizer but also improve the performance properties of the resulting adhesive. This invention provides microspheres of pressure sensitive adhesives containing unsaturated vinyl additives with an ionic portion and a hydrophobic portion to improve stability and performance properties. In addition, these adhesive microspheres adhere to the substrates, are removed cleanly and are capable of being re-applied multiple times if desired. Even with the improved adhesion, the adhesive microspheres of the present invention non-destructively adhere to brittle surfaces such as paper.

In particular, the present invention provides an adhesive microsphere composition comprising: (a) a plurality of polymeric elastomeric microspheres, wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one monomer of ( met) alkyl acrylate of 4 to 14 carbon atoms and optionally at least one comonomer; (b) from 0.1 to 3 parts by weight of at least one vinyl unsaturated additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms, preferably about 0.5 to about 3 parts by weight of the microspheres; (c) optionally, a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres, preferably about 0.1 to about 1.5 parts by weight per 100 parts by weight of the microspheres; (d) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the microspheres, preferably not more than 3 parts by weight, and more preferably in the range of 0.2 to about 1.5 parts by weight per 100 parts by weight of the microspheres; (e) optionally a modifier, wherein the modifier can be at least one of a chain transfer agent, a thickener, a solvent or the like in an amount that is sufficient to provide microspheres with a solvent soluble portion in the range of 30-98%, preferably in the range of 40-95%, wherein the solvent is n-heptane; and (f) an initiator in an amount effective to catalyze the polymerization reaction present in amounts in the range of about 0.1 to about 2 parts by weight per 100 parts by weight of the monomeric, polymerizable starting material. As used in this application, the term "(meth) acrylate" refers to acrylate and methacrylate. The vinyl unsaturated additive having an ionic portion and a hydrophobic portion and containing at least 5 but not more than 40 carbon atoms, improves the stability of the suspension polymerization process, resulting in little coagulation when the formulations are compared. they do not contain it. In addition, the use of the vinyl unsaturated additive results in improved adhesive performance. In addition, stable, high solids suspension polymerizations can now be performed. A modifier can be used to regulate the solvent soluble portion of the microspheres, and is added to the polymerization mixture in an amount sufficient to provide a solvent soluble portion 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 solvent soluble portion. Such amounts could be in the range, for example, for 1-30% solvents, for 1-30% thickeners, and for chain transfer agents, up to about 0.15%. Particularly useful modifiers are chain transfer agents. To control the molecular weight of the polymer that forms in the microsphere, a chain transfer agent, or modifier, is used. Many halogen-containing and sulfur-containing organic compounds function well as chain transfer agents in free radical polymerizations. Non-limiting examples of such agents are: carbon tetrabromide, carbon tetraeloride, dodecanethiol, iso-octylthioglycolate, butyl mercaptan, and tertiary dodecyl mercaptan. Particularly useful chain transfer agents are long chain mercaptans, such as dodecanethiol. The amount of the chain transfer agent suitable for microsphere polymerizations is calculated on a weight basis to the complete 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 for providing a polymer component soluble in solvent in the microsphere of up to about 98%. Other useful modifiers are solvents. Examples of which are, but are not limited to: aliphatic or aromatic solvents such as heptane, benzene, toluene and the like; alcohols such as methanol, isopropyl alcohol, and the like; and ketones such as acetone, methyl ethyl ketone and the like. The amount of solvent suitable for the microsphere polymerizations is calculated on a basis by weight to the complete polymerizable content. The solvent is preferably added up to about 30%, more preferably up to about 15% and still more preferably up to about 5%. These levels are suitable for providing a polymer component soluble in solvent in the microspheres of up to about 98%. Other useful modifiers include thickeners and / or plasticizers. Examples of which are, but are not limited to: hydrogenated turpentine resin esters, commercially available from companies such as Hercules, Inc., under the trade names of Foral ™, Regalrez® and Pentaly ™. Thickening resins also include those based on t-butyl tyrosine. Useful plasticizers include, but are not limited to, dioctyl phthalate, 2-ethylhexyl phosphate, tricresyl phosphate, mineral oil, and the like. The thickener and / or plasticizer are preferably added up to about 30%, more preferably up to about 15% and still more preferably up to about 5%. These levels provide a polymer component soluble in solvent in the microsphere of up to about 98%. In yet another aspect of the present invention there is provided a one step suspension polymerization process for preparing polymeric elastomeric microspheres, comprising the steps of: (a) stirring a mixture comprising polymerizable monomeric starting materials, comprising : (i) at least one alkyl (meth) acrylate monomer of 4 to 14 carbon atoms and, optionally at least one comonomer; (ii) from 0.1 to 5 parts by weight of at least one unsaturated vinyl additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms; (iii) an initiator for the polymerizable monomeric starting materials, present in amounts in the range of 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials; (iv) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials; (v) a surfactant 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; (vi) water to form an oil-in-water suspension; and (vii) optionally a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (b) polymerizing the monomer (s) of (meth) acrylate and the comonomer (s), if present, wherein microspheres are provided. In still another aspect, the present invention provides a two step suspension polymerization process for preparing polymeric, elastomeric microspheres from monomeric, polymerizable starting materials, wherein the process comprises the steps of: (a) stirring a mixture comprising: (i) at least one monomer of (meth) alkyl acrylate of 4 to 14 carbon atoms; (ii) from 0.1 to 5 parts by weight of at least one unsaturated vinyl additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms; (iii) an initiator for the monomer present in amounts in the range of 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials; (iv) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials; (v) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials, preferably not more than 3 parts by weight and more preferably in the range of 0.5 to 2 parts by weight; (vi) optionally a modifier in an amount sufficient to provide a solvent soluble portion in the range of 30-98%; and (vii) water to form an oil-in-water suspension; (b) at least partially polymerizing the polymerizable monomeric starting materials. (c) adding at least one comonomer to the suspension; and (d) continuing the polymerization of polymerizable monomeric starting materials; wherein the microspheres are provided. The present invention also provides in another additional aspect a sheet material comprising a liner and reinforcement and a repositionable pressure sensitive adhesive coating, described above, which is coated on at least a portion of at least one larger surface . Various characteristics of the adhesive of the present invention provide a number of desirable advantages that have not been available to date.

For example, various advantages include (a) improved adhesion to various surfaces (bond paper, cloth, wood, painted surfaces, glass, vinyl, etc.), (b) adhesive microspheres that can be prepared at a high proportion of solids ( 55% or more) without large amounts of clot, (c) adhesive microspheres that are more stable to coagulation or agglomeration, and (d) adhesive microspheres that adhere to a substrate or reinforcement and are easily removed from applied surfaces without transfer or leave a residue of adhesive on the applied surface. In addition, the present invention provides a microsphere-based pressure sensitive adhesive, which has a high solvent soluble fraction, which adheres to rough surfaces such as cloth, is removed cleanly, and exhibits the ability to be reapplied multiple times if is desired Even with this improved addition to the rough surfaces, the adhesive microspheres will non-destructively adhere to brittle surfaces such as paper. In addition, the adhesive microspheres of this invention are prepared according to the methods of efficient resources.

DESCRIPTION OF THE PREFERRED MODALITIES The microspheres obtained in the present invention are 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, (b) optionally, a comonomer, (c) at least one vinyl unsaturated additive having an ionic portion and a hydrophobic portion containing at least 5 but not more than 40 carbon atoms, and (d) optionally, a modifier in one sufficient amount to provide a solvent soluble portion in the range of 30-98%. The comonomer (b), if present, can be non-polar, ionic, polar or mixtures of such monomers. Useful alkyl (meth) acrylate monomers are those monofunctional unsaturated (meth) acrylate esters, the alkyl 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) acrylates are those which, as homopolymers, generally have a glass transition temperature below about -20 ° C, or if a combination of monomers is used, such a combination could produce a copolymer or terpolymer having generally a glass transition temperature below about -20 ° 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 acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, sec-butyl acrylate and mixtures thereof. . The vinyl ester monomers suitable for use in the present invention include, but are not limited to: vinyl 2-ethexanoate, vinyl caprylate, vinyl laurate, vinyl pelargonate, vinyl hexanoate, vinyl propionate, decanoate of vinyl, vinyl octanoate, and other monofunctional unsaturated vinyl esters of linear or branched carboxylic acids containing from 1 to 14 carbon atoms, which as homopolymers have glass transition temperatures below about -10 ° C. Preferred vinyl ester monomers include vinyl laurate, vinyl capryate, vinyl 2-ethylhexanoate, and mixtures thereof. Other additional vinyl monomers, which, as homopolymers, have glass transition temperatures greater than about -10 ° C to 0 ° C, such as vinyl acetate, acrylonitrile, styrene, mixtures thereof and the like, can optionally be used in conjunction with one or more of the acrylate, methacrylate and vinyl ester monomers, with the proviso that the vitreous transition temperature of the resulting polymer is below about -10 ° C. Suitable vinyl unsaturated additives having an ionic portion and a hydrophobic portion and containing at least 5 but not more than 40 carbon atoms include: the salts of sulfoesters of alpha-methylenic carboxylic acids, such as 2-sulfoethyl acrylate, methacrylate of 2-sulfoethyl, 2-sulfoethyl a-ethylacrylate, 2-sulfoethyl a-hexylacrylate, 2-sulfoethyl a-cyclohexylacrylate, 2-sulfoethyl a-chloroacrylate, 2-sulfo-1-propyl acrylate, acrylate and methacrylate of 2-sulfo-1-butyl, 3-sulfo-2-butyl acrylate, 2-methyl-1-sulfo-2-propyl acrylate and methacrylate, 3-bromo-2-sulfo-1-propyl acrylate, acrylate of 3-chloro-2-sulfo-1-propyl, 3-chloro-2-sulfo-1-butyl acrylate, 3-methoxy-2-sulfo-1-propyl acrylate, 2-sulfocyclohexyl acrylate, 2-acrylate, phenyl-2-sulfoethyl, 4-sulfo-1-butyl acrylate, acrylate and 6- (sulfophenoxy) hexyl methacrylate. The preparation of such materials is described in U.S. Patent No. 3,024,221, the disclosure of which is incorporated by reference herein. The salts of sulfate esters of carboxylic acids of al-methylene include 3-sulfate-2-hydroxy-1-propyl methacrylate. The carboxyl-terminated alkyl ester salts of the alpha-methylene carboxylic acids include 11-methacryloxyundecanoic acid.

The salts of sulfoalkylalkyl ethers include the allyl ether of 3-sulfo-2-hydroxy-1-propyl. The acrylamide alkalesulfonate salts include 2-acrylamido-2-methyl propanesulfonates. Salts of vinyl alkylphosphonate esters include vinyl octylphosphonates. The salts of vinyl aryl sulfonates include para-is tyrosulfonates. Typically, the vinyl unsaturated additive having an ionic portion and a hydrophobic portion, it is present in relative amounts by weight of the total polymerizable content of from about 0.1 to about 3 parts and preferably from about 0.5 to about 3 parts. Suitable comonomers include non-polar, ionic, polar monomers and mixtures thereof. In addition to using one or more acrylate monomers as a comonomer, as described above, the following are non-limiting examples of comonomers. (A) ionic comonomers, such as sodium methacrylate, ammonium acrylate, sodium acrylate, (1) trimethylamin-p-vinyl-benzimide, (II) 4,4, 9-trimethyl-4-azonia-7-oxo- 8-oxa-dec-9-en-l-sulfonate, (III) N, N-dimethyl-N- (β-methacryloxyethyl) ammonium betain-propionate, (IV) trimethylamine methacrylamide, (V) methacrylimide of 1, 1-dimethyl-1 (2,3-dihydroxypropyl) amine; any amphoteric monomer and the like. (B) Non-polar comonomers include but are not limited to, 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, isodecyl methacrylate, t-butyl acrylate, 1-butyl methacrylate, isobornyl acrylate, octylacrylamide, methyl methacrylate, isononyl acrylate, isodecyl acrylate, styrene and the like, and combinations thereof. (C) The polar comonomers may or may not contain a dissociable hydrogen. Examples of suitable polar comonomers include organic carboxylic acids comprising 3 to about 12 carbon atoms and having in general from 1 to about 4 carboxylic acid moieties. Non-limiting examples of such monomers include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, maleic acid, β-carboxyethyl acrylate, and the like. In addition, suitable polar comonomers include acrylamide, methacrylamide, 2-hydroxyethyl acrylate, and the like. In addition, a class of suitable comonomers are the amino functional group monomers having a core or core portion of the general formula (a): OR CH2 = CHR? -C-L-R2- (NR3R4) x (1) wherein Ri is -H, -CH3 -CH2CH3, cyano or carboxymethyl; R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms; R3 and R4 are independently hydrogen or an alkyl group containing 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 comonomers according to formula (I) include N, N-dimet i l -aminoethyl (methyl) acrylate, β, β-dimethylaminopropyl- (meth) acrylate, t-butylammonioethyl (methyl) acrylate and ?,? -dieti laminoacrylate. Yet another class of suitable comonomers are comonomers having a core or core portion of the general formula (2): O, IICH2-CHRi-C ~ L-R2 (R5) xRe (2) wherein Ri is H, -CH3, -CH2CH3, cyano or carboxymethyl; R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms; R5 is -O-, alkylene oxide comprising 1 to 5 carbon atoms, or phenoxy oxide, wherein the alkylene oxide could include -CH20-, -CH2CH2O-, -CH2 (CH) CH3O-, and the like. R6 is H, -C6H4OH, or -CH3 L is a carbon-carbon bond, O,? H or S; and x is an integer with the proviso that when R5 is -O-, x is an integer of 1-3.

Non-limiting examples of comonomers according to formula (2) include hydroxyethyl (meth) acrylate, glycerol mono (meth) acrylate and 4-hydroxybutyl (meth) acrylate, poly (ethylene oxide) terminated in acrylate; poly (ethylene oxide) terminated in methacrylate; methoxy poly (ethylene oxide) methacrylate; butoxy-poly (ethylene oxide) methacrylate; poly (ethylene glycol) terminated in acrylate; poly (ethylene glycol) terminated in methacrylate; methoxy poly (ethylene glycol) methacrylate, butoxy poly (ethylene glycol) methacrylate and mixtures thereof. Yet another class of suitable comonomers are amide functional group monomers having a nucleus or core portion of the general formula (3) : 0 CH2 = CHR? -C-NR3R4 (3) wherein Ri is H, -CH3, -CH2CH3, cyano or carboxymethyl; R3 and R4 are independently hydrogen or an alkyl group containing 1 to about 12 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety. Non-limiting examples of comonomers according to formula (3) include N-vinylpyrrolidone, N-vinyl caprolactam acrylamide or N, N-dimethylacrylamide. Non-limiting examples of other suitable comonomers that do not fall within the above classes, but which are within the scope of the allowable comonomers include (meth) acrylonitrile, furfuryl (meth) acrylate and tetrahydrofurfuryl (meth) acrylate, 2-vinylpyridine, and 4-vinylpyridine. Typically, when a comonomer is present, the relative amounts by weight of the monomer (s) of alkyl (meth) acrylate and the comonomer are in the range of about 99.5 / 0.5 to 75/25, and preferably are in the range of 98. / 2 to 92/8. A modifier can be used to regulate the solvent soluble portion of the microspheres, and is added to the polymerization mixture in an amount sufficient to provide a solvent soluble portion 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 solvent soluble portion. Such amounts could be in the range for example for solvents of 5-30%, for thickeners and / or plasticizers of 1-30% and for chain transfer agents of up to about 0.15%. Particularly useful modifiers are chain transfer agents to control the molecular weight of the polymer that forms in the microsphere, it is desirable to use a chain transfer agent or modifier. Many organic compounds containing halogen and sulfur function as chain transfer agents in free radical polymerizations. Non-limiting examples of such agents are: carbon tetrabromide, carbon tetraeloride, dodecanethiol, iso-octyl thioglycolate, butyl mercaptan, and tertiary dodecyl mercaptan. In this invention, it is effective to employ long chain mercaptan such as dodecanethiol. The amount of the chain transfer agent suitable for these microsphere polymerizations is calculated on a weight basis to the complete polymerizable content. The chain transfer agent is preferably added to about 0.15%, more preferably to about 0.12%, and still more preferably to about 0.08%. These levels are suitable to provide a soluble polymer content in the microsphere of up to about 98%. The adhesive microsphere composition may also contain a crosslinking agent. Examples of useful crosslinking agents include, but are not limited to: multifunctional (meth) acrylate (s), for example, butanediol diacrylate or hexanediol diacrylate or other multifunctional crosslinkers such as divinylbenzenes and mixtures thereof. When used, the crosslinker (s) is aggregated at a level of up to about 0.15 weight percent equivalent, preferably up to about 0.1 weight percent equivalent, of the total polymerizable composition, with the proviso that the crosslinking agent combination and the modifier concentrations are chosen to obtain a microsphere with 30 to 98% of the solvent soluble portion. The adhesive microspheres of the present invention are prepared by suspension polymerization using either the one-step or two-step process as described in detail below. The suspension polymerization is a process in which a monomer is dispersed in a medium (usually aqueous) in which it is insoluble. The polymerization proceeds within individual polymer droplets. Precursors are preferably used by free radicals, soluble in monomer. The kinetics and the mechanism are those for the corresponding bulk polymerization, under similar conditions of temperature and concentration of initiator. The initiators that affect the polymerization are those that are normally suitable for the free radical polymerization of the 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-acetophenone.

Other suitable initiators include lauroyl peroxide and bis (t-butylcyclohexyl) peroxy dicarbonate. The initiator or mixture of initiators are present in a catalytically efficient amount, sufficient to give rise to the high monomer conversion in a predetermined time interval and temperature range. Typically, the initiator is present in amounts in the range of 0.1 to about 2 parts by weight per 100 parts by weight of the monomeric, polymerizable starting materials. The parameters that affect the concentration of the initiator employed include the type of the initiator and the particular monomer and / or monomers involved. In addition, mixtures of initiators can be used to control the speed of the polymerization reaction. It is believed that the catalytically effective concentrations are in the range of 0.02 to about 2 weight percent of the total monomers and more preferably, about 0.20 to about 0.70 weight percent of the monomer and / or monomers. Optionally, a polymeric stabilizer can be used. Advantageously, the presence of the stabilizer allows the use of relatively low amounts of the surfactant, while still obtaining microspheres. Any polymeric stabilizer that effectively provides sufficient stabilization of the final polymerizable droplets and prevents agglomeration within a suspension polymerization process is useful in the present invention. When used, a polymeric stabilizer will typically be present in the reaction mixture in a weight amount of about 0.1 to about 3 parts by weight per 100 parts of the polymerizable monomer, and more preferably will be present in a weight amount of about 0.1 to about about 1.5 parts by weight per 100 parts of the polymerizable monomer. Exemplary polymeric stabilizers include salts of polyacrylic acids of weight average molecular weight greater than 5,000 (eg, ammonium, sodium, lithium and potassium salts), carboxyl-modified polyacrylamides (eg, Cyanamer ™ A-370 from American Cyanamid ), copolymers of acrylic acid and dimethylaminoethyl methacrylate and the like, polymeric quaternary amines (for example, General Analine and Film 's Gafquat ™ 755, a copolymer of quaternized polyvinylpyrrolidone, or "JR-400" of Union Carbide, a substituted cellulosic material) with quaternized amine), cellulosics, carboxyl-modified cellulosics (eg, Natrosol ™ CMC type 7L of Hercules, sodium carboxymethylcellulose), and polyvinyl alcohols.The surfactants will typically be present in the reaction mixture in an amount not greater than about 5 parts. by weight per 100 parts by weight of the polymerizable monomer, preferably not greater than about 3 parts by weight, and more preferably in the range of 0.2 to 1.5 parts by weight per 100 parts by weight of the polymerizable monomer. Useful surfactants (also known as emulsifiers) include anionic, cationic, or non-ionic surfactants and include, but are not limited to, anionic surfactants, such as alkylaryl ether sulfates and -sulfonates such as sodium alkylaryl ether sulfate, for example Triton ™ X200, available from Rohm and Hass, alkylaryl polyether sulfates and -sulfonates such as alkylaryl poly (ethylene oxide) -sulfates and -sulfonates, preferably those having up to about 4 repeating ethyleneoxy units, and alkyl sulphates and -sulfonates such as sodium lauryl sulfate, lauryl sulfate of ammonium, triethanolamine lauryl sulfate, and sodium hexadecyl sulfate, alkyl ether sulphates and sulphonates such as ammonium lauryl ether sulfate, and alkyl polyether sulfates and sulphonates such as alkyl polyethylene oxide sulfates and sulfonates, preferably those which they have up to about 4 ethyleneoxy units. Alkyl sulfates, alkyl ether sulfates, and alkylarylether sulfates are preferred. Additional anionic surfactants may include, for example, alkylaryl sulfates and -sulfonates, for example, sodium dodecylbenzenesulfate and sodium dodecylbenzenesulfonate, sodium and ammonium salts of alkyl sulfates, for example sodium lauryl sulfate, and ammonium lauryl sulfate.; nonionic surfactants, such as ethoxylated oleyl alcohol and polyoxyethylene octylphenyl ether; and cationic surfactants such as a mixture of alkyldimethylbenzylammonium 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 sulphobetaines, N-alkylaminopropionic acids, and N-al qui-betaines. To initiate the polymerization reaction, a sufficient number of free radicals must be present. This can be accomplished through various means that are well known in the art, such as initiation by free radicals by heat or radiation. For example, heat or radiation can be applied to initiate the polymerization of the monomers, which is an exothermic reaction. However, it is preferred to apply heat until the thermal composition of the initiators generates a sufficient number 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 often desirable. It is well known that dissolved oxygen in the reaction mixture can inhibit polymerization and it is desirable to expel this dissolved oxygen. However, an inert gas bubbled into the reaction vessel or through the reaction mixture is an effective means for deoxygenation, although other techniques for deoxygenation that are compatible with suspension polymerization can be used. Typically, nitrogen is used to deoxygenate, although any of the inert gases of Group VIIIA (CAS version) are also suitable. While the specific parameters of time and rate of agitation are dependent on the types of initiator monomers used, it is desirable to pre-disperse the reaction mixture until the reaction mixture reaches a state where the average droplet size of the monomer is between about 1. μm and 300 μm, and preferably between 20 μm and 70 μm. The average particle size tends to decrease with the increased and prolonged agitation of the reaction mixture. Preferably, stirring and purging with nitrogen are maintained throughout the reaction period. The initiation is started by * -heating the reaction mixture. After polymerization, the reaction mixture is cooled. In a one-step process, the alkyl (meth) acrylate monomer and any optional comonomers are present together in the suspension at the start of the polymerization.

In a two-step process, any optional comonomer is typically added after the initial exotherm, which results from the polymerization of the promoted (meth) acrylate monomer, but could be added at any point after the start of the polymerization. The other components, such as the initiator, the stabilizer (if used), the surfactants and the modifiers are present in the reaction mixture as described in the processing steps described hereinabove. After the polymerization, an aqueous, stable suspension of microspheres is obtained at room temperature. The suspension can have a non-volatile solids content of about 10 to about 70 weight percent. After prolonged rest, the suspension is typically separated into two phases, with one phase being aqueous, the phase essentially free of polymeric microspheres, and the other phase being an aqueous suspension of the polymeric microspheres, i.e., the phase rich in microspheres. The aqueous suspension of microspheres can be used immediately after 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 suitable for conventional coating techniques and have improved fluid processing characteristics. The phase rich in microspheres can. be diluted with an additional amount of solvent or water, or redispersed after agitation or other means of agitation. In general, this aqueous suspension can be coated on a reinforcement or other substrate that is employed using conventional coating methods, such as slit die coating, to provide an adhesive coating. The microspheres can be composed of 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 2.1 g / m2 to about 21 g / m2 (0.2 to about 2 grams per square foot) to provide a sheet material coated with adhesive in which the adhesive coating comprises polymeric microspheres, surfactant, and optionally polymeric stabilizers, rheology modifiers, and / or latex adhesives. Alternatively, the microspheres can be isolated and combined with an organic solvent if desired, before coating them on the reinforcement. The properties of the adhesive microspheres of the present invention can be altered by the addition of one or more thickener resins and / or one or more plasticizers after the polymerization. Preferred thickeners and / or plasticizers for use herein include commercially available hydrogenated rosin rosin esters available from companies such as Hercules, Inc., under the trade names of ForaT Regalrez Pentalyn Thickening reams also include those based on t-butyl tyrosine. Useful plasticizers include, but are not limited to: dioctyl phthalate, 2-ethylhexyl phosphate, tricresyl phosphate, and the like. If such thickeners and / or plasticizers are used, the amounts used in the adhesive mixture are effective amounts for the known uses of such additives.

Optionally, adjuvants such as rheology modifiers, colorants, fillers, stabilizers, pressure sensitive latex binders and various other polymeric additives may be used. If such adjuvants are used, the amounts used in the adhesive mixture are effective amounts for the known uses of such adjuvants. The reinforcements used as substrates for adhesive articles may be of materials that are conventionally used as a tape reinforcement or may be of other flexible material. Such reinforcements include, but are not limited to, those made of 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 trade designation of 3M "Scotch" 8050 film), polyamide films such as that available from DuPont Co. , Wilmington, DE, under the trade designation "KAPTON", cellulose acetate and ethylcellulose. The reinforcements may also be woven fabric formed from synthetic or natural yarns such as cotton, nylon, rayon, glass, or ceramic material, or these may be non-woven fabric such as natural air-laid flat nets or synthetic or mixtures thereof. In addition, the reinforcement may be formed of materials selected from a group consisting of metal, metallized polymeric film, and ceramic sheet material. Such preferred materials include, but are not limited to, plastics such as polyethylene, polypropylene, polyesters, cellulose acetate, poly (vinyl chloride), and poly (vinylidene fluoride), as well as paper or other substances 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 reinforcements or liners could have such release characteristics. In general, the reinforcing or substrate material is from about 50 μm to about 155 μm in thickness, although thicker and thinner substrate reinforcement materials are not excluded. Particularly useful articles prepared using the adhesive microspheres of the present invention include reclosable adhesive products such as note products and relocatable papers, relocatable tape and ribbon labels, easel or lectern sheets, reclosable adhesive pencil and the like, may also include other products industrial commercials and medical adhesives, not relocatable. The present invention is further illustrated by the following examples, but the particular materials and amounts thereof indicated in these examples, as well as other functions and details, should not be considered as unduly limiting this invention. All materials are commercially available or known to those skilled in the art, unless otherwise stated or apparent. The following examples are illustrative in nature and are not intended to limit the invention in any way. All the percentages listed in the following Tables are calculated on a weight basis to the total monomer and to the content of unsaturated vinyl additive.

Eg emplos Test Methods With Sun Pollution T ubl e in Sol ven te To determine the content of the solvent-soluble material of the prepared microspheres, the following process is used. One gram of the aqueous suspension of microspheres is dried in a vacuum oven without heat.

After drying, 100 ml of n-heptane are added and stirred for 24 hours. After stirring, the dispersion is emptied through a filter paper (30 micron pore) to remove the insoluble content.

The filtrate is then dried in an oven at 38 ° C (100 ° F). The weight of the dry filtrate divided by the dried suspension microspheres is the percent solvent soluble polymer content. The test is repeated and the data is reported as the average number of tests.

Recubrimi in to of My croesferas Adhesi vas A sample coating of adhesive microspheres is made by allowing the suspension to acme. The cream (the microsphere-rich phase) is then coated through a space of 25 microns (1 mil) on a matte polyester film of 62.5 microns (available from 3M Company as Scotch 8050).

Adhesion to Decay in Bond Paper Adhesion to detachment 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 is expressed in grams by a width of 2.54 cm (1 inch) of coated sheet. The procedure followed is: A strip, 2.54 cm (1 inch) wide, of coated sheet is applied to the horizontal surface of a 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 the bond paper. The free end of the coated sheet is coupled to the adhesion tester load cell, such that the withdrawal angle is 90 degrees. The test plate is then clamped in the jaws of the tensile test machine, which is capable of moving the plate away from the load cell, at a constant speed of 30.8 centimeters per minute. A load cell reading in grams per 2.54 cm (1 inch) of coated sheet is then recorded. The samples are tested three times. The average value of the three tests is reported.

Gl osari or AA - acrylic acid AmA - ammonium acrylate ACM - acrylamide HEMA - hydroxyethyl methacrylate IOA - isooctyl acrylate IPA - isopropyl alcohol NVP - N - vinylpyrrolidone RH - relative humidity NaSS - is sodium tyrosulfonate AMPS - 2 - acrylamido - 2 - met ammonium salt ilpropansulfonate) N-tertiary OAcM-octylacrylamide DMAM-1,1-dimethyl-l (2-hydroxypropyl) aminomethacrylimide PTSAN - para-toluenesulfonic acid (sodium salt) Example 1 A two-liter three-necked flask equipped with a mechanical stirrer, thermometer and nitrogen inlet tube was charged with 602.75 g of deionized water, 35 g 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), 17.5 grams of a 10% solids solution of Goodrite K702 (trade name for a solution of 25% solids of polyacrylic acid, of average molecular weight by weight of 240,000, commercially available from BF Goodrich Company) which had been neutralized to a pH of 7.0 with concentrated ammonium hydroxide, and 2.63 g of sodium styrenesulfonate. To this solution were added 347.37 g of isooctyl acrylate and 1.05 g of Perkadox 16 N (trade name for a 95% active bis (4-tert-butylcyclohexyl) peroxydicarbonate, initiator commercially available from AKZO Chemicals Inc.).

The stirring speed was adjusted to 400 revolutions per minute (RPM), and the reaction mixture was heated to 50 ° C, and purged with nitrogen. Agitation, and nitrogen purge were maintained throughout the reaction period. The reaction was initially adjusted to 50 ° C and an exotherm was obtained after a few minutes and reached a maximum of 77 ° C. The batch was kept at 50 ° C for 22 hours, cooled and filtered through a blanket of sky. The weight of the clot collected on the sky blanket was measured and reported as the% clot by weight to the content of monomer and vinyl unsaturated additive. The particle size was 36 μ.

Ex empl o 2 - 8 The examples were prepared according to the procedure described in Example 1, except that the type and amount of emulsifying monomer, the amount of the dodecanethiol and the amount and type of the comonomer were changed. The formulations and the test results are summarized in Tables 1 and 2 below.

Table 1 Table 2 Examples Use Compare C1 -C9 These examples were prepared according to the procedure described in Example 1, except that the vinyl unsaturated additive was omitted. The formulations and the test results are summarized in Tables 3 and 4 below.

Table 3 Table 4 * unstable, coagulated in the particle size analyzer The results in Tables 1 and 2 show that the samples of this invention with a low level of vinyl unsaturated additive result in microspheres that have improved adhesion to bond paper and are more stable during the polymerization exhibited by the lower levels of clot and they are better recolocables adhesives.

The. results with comparative examples made without any unsaturated vinyl additive, result in microspheres that coagulate completely or, at best, have higher clot levels and poorer adhesion to bond paper at comparable levels of the soluble portion percent in solvent. Examples 1-8 and C1-C9 were prepared at 35% solids.

Ex empl o Compare ti vo CI O Example 1 of European Patent EPO 0,209,337 Case Bl was attempted as described in the case. However, when 7.5 grams of the monomer of 1- (3-sulfopropyl) -2-vinyl-pyridinium betaine (SPV) was added to the co-solvent of 27.5 ml of equal proportions of ethanol / toluene and stirred for two hours, the SPV was not dissolved. Since the example established that the dissolution might not occur, the additional preparation of this example could be achieved.

Example 9 To a two-liter three-necked flask equipped with a thermometer, mechanical stirrer and nitrogen inlet tube was charged 507 g of deionized water, 27 g of a 10% solution of Stepanol AMV solids, 16 g of a 10% solution of Goodrite K702 which had been neutralized at a pH of 7.0 with concentrated ammonium hydroxide, and 1125 g of sodium styrenesulfonate. To this solution were added 450 g of isooctyl acrylate and 0.698 g of Pekadox 16 N and 0.698 g of Lucidol 75. The reaction mixture was stirred at 400 RMP, heated to 45 ° C and purged with nitrogen. Agitation and nitrogen purge were maintained throughout the reaction period. The reaction had an exotherm after a few minutes and a maximum of it at 83 ° C. The batch was kept at 60 ° C for 4 hours, cooled and filtered through a blanket of sky. No clot was seen in the flask or on the blanket of the sky. The particle size analysis indicated a mean volume diameter of 41 microns.

Examples 10 and 11 Examples 10, 11 and C11-C14 were repeated in a manner similar to that used in Example 9, except that the type and amount of the vinyl unsaturated additive and the type and amount of the comonomer were varied as indicated in Table 5 Table 5 The results in Table 5 show that sodium tyrosulphonate can stabilize an otherwise unstable (compare example 11 to C14 and example 9 to Cll, C12). Also, the non-functionalized PTSAN does not show the stabilizing effect shown by sodium styrene sulfonate. All samples in Table 5 were made at a solids content of 45%.

Example 12 259 g of deionized water, 21 grams of a 10% solution of Stepanol AMV solids, 6 g of an aqueous solution, were charged to a three-neck, two-liter flask equipped with a thermometer and nitrogen inlet tube. 10% solids from Goodrite K7200 (trade name for a 40% solids solution of poly (sodium acrylate), 20 wt., 000, commercially available from B.F. Goodrich Company), and 3.5 grams of sodium tyrosulfonate. To this solution was added a solution of 329 g of isooctyl acrylate, 5.25 g of HEMA, 5.25 g of NVP, 7 g of a 1% by weight solution of tert-dodecyl mercaptan dissolved in IOA, 0.123 g of Perkadox 16 N and 0.525 g Lucidol 75. The reaction mixture was stirred at 340 RPM, heated to 42 ° C and purged with nitrogen. Agitation and purging with nitrogen were maintained throughout the reaction period. The reaction had an exotherm after a few minutes and a maximum of this at 75 ° C. The batch was maintained at 75 ° C for 4 hours, cooled and filtered through a blanket of sky. No clot was seen in the flask or on the blanket of the sky. The particle size analysis indicated an average volume diameter of 45 microns. The percent of the solvent soluble portion was 33%.

Example C15 Example C15 was carried out in a manner similar to Example 12, except that the NaSS was replaced with 3.5 g of AA which was subsequently neutralized with ammonium hydroxide to pH 7. Massive coagulation of the suspension occurred during the polymerization. Example C16 was carried out in a manner similar to that of Example 12, except that NaSS was not added. The reaction coagulated.

The results in Table 6 show that the microspheres prepared without NaSS were not stable.

Table 6 The results in Table 6 show that without the use of styrene sodium fonate, the suspension polymerization is not stable. Examples 12 and C15, 16 were made at a solids content of 55%.

Example 1 3 Example 13 was prepared at a solids content of 65%. This example illustrates that low cost suspensions, with very high solids content of the adhesive microspheres, can be made using the teachings of this invention. To a three-neck, two-liter flask equipped with a thermometer, mechanical stirrer and nitrogen inlet tube were charged 160 g of deionized water, 21 g of a 10% solids solution of Stepanol AVM, 7.0 g of a 10% solution of Goodrite K7200 solids, and 1.75 g of sodium tyrosulfonate. To this solution was added a solution of 346.5 g of isooctyl acrylate, 1.75 g of AA, 0.070 g of Perkadox 16 N and 0.350 g of Lucidol 75. The reaction mixture was stirred at 300 RPM, heated to 42 ° C and it was purged with nitrogen. Agitation and nitrogen purge were maintained throughout the reaction period. The reaction had an exotherm after a few minutes, then an insulated liner was placed over the reaction flask. The reaction temperature had a maximum at 74 ° C and the liner was removed. The batch was kept at 65 ° C for 4 hours, cooled and filtered through a blanket of sky. The suspension was filtered slowly (but completely) due to its relatively high viscosity. No clot was observed. The particle size analysis indicated a mean volume diameter of 57 micrometers. The solvent soluble portion was 22%. Various modifications and alterations of this invention will become apparent to those of skill in the art, without departing from the spirit and principles of this invention, and it should be understood that this invention should not be unduly limited to the illustrative embodiments described hereinabove. . All publications and patents are incorporated herein by reference to the same degree as if each individual publication or patent was specifically and individually indicated to be 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.

Claims (20)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A stabilized microsphere adhesive composition, characterized in that it comprises: (a) a plurality of elastomeric, polymeric microspheres, wherein the microspheres are the reaction product of reactants comprising polymerizable starting materials comprising at least one (meth) acrylate monomer of alkyl of 4 to 14 carbon atoms and optionally at least one comonomer; (b) at least one unsaturated vinyl additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms, in an amount of about 0.1 to 3 parts by weight of the microspheres, ( c) optionally, a polymeric stabilizer in an amount of between about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres, (d) a -surfactant in an amount of not more than about 5 parts by weight per 100 parts in weight of the microspheres, (e) optionally a modifier, wherein the modifier can be at least one of a chain transfer agent, a thickener, a solvent or the like in an amount that is sufficient to provide microspheres with a portion soluble in n-heptane in the range of 30-98%, and (f) an initiator in an amount effective to catalyze the polymerization reaction present in amounts in the range of about 0.1 ha. about 2 parts by weight per 100 parts by weight of the polymerizable, monomeric starting material.

2. The adhesive composition of stabilized microspheres according to claim 1, characterized in that the vinyl unsaturated additive is the salts of sulfoesters of alpha-methenecarboxylic acids, the salts of sulfate esters of alpha-methylenecarboxylic acids, the salts of the carboxyl-terminated alkyl esters of alpha-methylenecarboxylic acids, salts of sulfoalkyl allyl ethers including allyl ether of 3-sulio-2-l? idxoj? il-pxopiJ-o, -s -salts of alkanesulfonates of acrylamide, the salts of the alkyl vinyl fonate esters, the salts of the vinyl aryl sulfonates and mixtures thereof.

3. The stabilized microsphere adhesive according to claim 2, characterized in that the vinyl unsaturated additive is a styrenesulfonate salt.

4. The stabilized microsphere adhesive according to claim 2, characterized in that the i-asaturated ad-it-ivo with vinyl is a salt of 2-acrylamido-2-methylpropanesulfonate.

5. The adhesive composition of stabilized microspheres according to claim 1, characterized in that the comonomer includes ionic monomers, non-polar monomers, polar monomers or mixtures thereof.

6. The adhesive composition of stabilized microspheres according to claim 5, characterized in that the ionic monomers include sodium methacrylate, ammonium acrylate, sodium acrylate, (I) trimethylamine-p-vinyl-benzimide, (II) 4.4, -tri; methyl-4-azonia-7-o-xo-ß-o-xa-dec-9-en-l-sulfonate; (III) propionate betaine of N, N-dimethyl-N (β-methacryloxyethyl) ammonium, (IV) trimethylamine-methacrylimide, (V) 1,1-dimethyl-l (2,3-dihydroxypropyl) amine-methacrylamide; any amphoteric monomer and mixtures thereof.

7. The adhesive composition of stabilized micxoesphexes according to claim 5, characterized in that the non-polar monomers include 4-methyl-2-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-acrylate, butyl, isodecyl methacrylate, t-butyl acrylate, t-butyl methacrylate, isobornyl acrylate, octylacrylamide, methyl methacrylate, isononyl acrylate, isodecyl acrylate, styrene and the like, and mixtures thereof.

8. The adhesive composition of stabilized micxoesphexes according to claim 5, characterized in that the polar monomers may or may not contain a dissociable hydrogen and include organic carboxylic acids comprising 3 to about 12 carbon atoms, and having in general 1 to about 4 portions of carboxylic acid, as well as acrylamide, methacrylamide, 2-hydroxyethyl acrylate, and mixtures thereof.

9. The adhesion-stabilization composition of stabilized micxoesfexes according to claim 1, characterized in that the comonó-mexo is an amino-functional amino-oxime that has the following general formula: (1) wherein Ri is -H-CH3, -CH2C? 3, cyano or carboxymethyl; R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms; J 3 and R 4 are independently hydrogen or an alkyl group containing 1 to about 12 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety; L is a carbon-carbon bond, O, NH or S; and x is an integer from 1 to 3.

10. The adhesive composition of stabilized microspheres of confounding with IB. Claim 1, characterized in that the comonomer has the following general formula: OR II CH2 = CHR? -C-L-R2 (R5) XR6 (2) wherein Ri is H, -CH3, -CH2CH3, cyano or carboxymethyl; R2 is a hydrocarbyl radical comprising 1 to about 12 carbon atoms; R5 is -O-, alkylene oxide comprising 1 to 5 carbon atoms, or phenoxy oxide, wherein the alkylene oxide could include -CH20-, -CH2CH20-, -CH2 (CH) CH3O-, and the like. R6 is H, -C6H4OH, or -CH3L is a carbon-carbon bond, O, NH or S; and x is an integer with the proviso that when R5 is -O-, x is an integer of 1-3.

11. The additive composition of stabilized micxoesfexes according to claim 1, characterized in that the comonomer is an amido-functional moxamidoxomer of the general formula: OR II CH2 = CHR? - C-NR3R4 (3) wherein Ri is H, -CH3, -CH2CH3, cyano or carboxymethyl; R3 and R4 are independently hydrogen or an alkyl group containing 1 to about 12 carbon atoms or an arylalkyl group or together form a cyclic or heterocyclic moiety.

12. The adhesive composition of stabilized micxoesfexes according to claim 1, characterized in that the comonomer is (meth) acrylonitrile, furfuryl (meth) acrylate and tetrahydrofurfuryl (meth) acrylate, 2-vinyl pyridine, or 4-vini 1-pyridine.

13. The adhesive composition of stabilized microspheres according to claim 1, characterized in that when a comonomer is present, the relative amounts by weight of the monomer (s) of alkyl (meth) -crylate and the comonomer are in the range of about 99.5. /0.5 to 75/25.

14. The adhesive composition of stabilized .micxoesfexes according to claim 1, characterized in that the surfactant is in an amount of about 0.2 to about 1.5 parts by weight per 100 parts by weight of the microspheres.

15. The adhesive composition of stabilized microspheres according to claim 1, characterized in that the modifier is a chain transfer agent.

16. The adhesive composition of microspheres stabilized by confounding with claim 1, characterized in that the modifier is a solvent.

17. The adhesive composition of my.croe = -fexes stabilized according to claim 1, characterized in that the odificadox is a thickener.

18. The adhesive composition of stabilized microspheres according to Claim 1, characterized in that the modifier is a plasticizer.

19. A one-step polymerization process for preparing polymeric elastomeric microspheres, characterized in that the process comprises the steps of: (a) stirring a mixture comprising polymerizable monomeric starting materials, comprising: (i) at least one monomer of (meth) alkyl acrylate of 4 to 14 carbon atoms and optionally at least one comonomer; (ii) from 0.1 to 3 parts by weight of at least one unsaturated vinyl additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms; (iii) an initiator for the polymerizable monomeric starting materials, present in amounts in the range of 0.1 - up to about 2 parts by weight per 100 parts by weight of the polymerizable monomeric niches; (iv) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials; (v) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the polymethyloxable monomer, (vi) water to form an oil-in-water suspension; and (vii) optionally a modifier in an amount sufficient to provide a n-heptane soluble portion in the range of 30-98%; and (b) the polymerization of the monomer (s) of (meth) acrylate and of the comonomer (s), if present, wherein microspheres are provided.

20. A two step polymerization process for preparing polymeric elastomeric microspheres, characterized in the process because it comprises the steps of: (a) stirring a mixture comprising: (i) at least one alkyl (meth) acrylate monomer of 4 to 14 carbon atoms; (ii) from 0.1 to 3 parts by weight of at least one unsaturated vinyl additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms; (iii) an initiator for the monomer present in amounts in the range of 0.1 to about 2 paxtes by weight per 100 wt.% of the polymerizable monomeric starting materials; (iv) optionally, a polymeric stabilizer in an amount in the range of 0.1 to about 3 parts by weight per 100 parts by weight of. the polymerizable monomeric starting materials; (v) a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the polymerizable monomeric starting materials, (vi) optionally a modifier in an amount sufficient to provide a portion soluble in n-heptane in the range from 30-98%; and (vii) water to form an oil-in-water suspension; (b) at least partially polymerizing the polymerizable monomeric starting materials. (c) adding at least one comonomer to the suspension; and (d) continuing the polymerization of the polymerizable monomeric starting materials; wherein the microspheres are provided. SUMMARY OF THE INVENTION An additive composition of stabilized microspheres is disclosed which comprises: a plurality of polymeric elastomeric microspheres, wherein the microspheres are the reaction product of reagents comprising polymerizable starting materials containing at least one alkyl (meth) acrylate monomer of to 14 carbon atoms and optionally at least one comonomer, at least one vinyl unsaturated additive having an ionic portion and a hydrophobic portion, and containing at least 5 but not more than 40 carbon atoms in an amount of about 0.1 to 3 parts by weight of .the microspheres; optionally, a polymeric stabilizer in an amount of about 0.1 and about 3 parts by weight per 100 parts by weight of the microspheres; a surfactant in an amount of not more than about 5 parts by weight per 100 parts by weight of the microspheres; optionally a modifier, wherein the modifier is at least one of a chain transfer agent, a thickener, a solvent, or the like, in an amount that is sufficient to provide microspheres with a soluble portion in n-heptane in the range of 30-98%; and f) an initiator in an amount effective to catalyze the polymerization reaction present in amounts in the range of about 0.1 to about 2 parts by weight per 100 parts by weight of the polymerizable monomeric starting material.