Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/21—Paper; Textile fabrics
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]

Definitions

• the present invention relates to an adhesive composition, a masking tape, a surface protection method, and a copolymer dispersion.
• Masking tape is used to temporarily protect the surface of the masked object in a wide range of fields such as architectural painting, automobiles, and home appliances, and is peeled off after the purpose of protection is achieved.
• the masking tape should be applied to the object to be masked before applying various topcoats (lacquer paint, water-based paint, etc.). It is attached to the surface and peeled off after the topcoat is applied and dried.
• a coating liquid in which an adhesive is dissolved or dispersed in a liquid medium is applied to one side of a base material made of paper (hereinafter referred to as a paper base material) and dried to form a paper base material.
• An adhesive layer is formed on one side of the Natural rubber-based, synthetic rubber-based, and acrylic-based adhesives are widely used, and acrylic-based adhesives in particular are characterized by their ability to impart various functions.
• the use of water as a liquid medium has been extensively studied.
• Various techniques have been disclosed regarding acrylic water-based pressure-sensitive adhesives exhibiting peelability suitable for applications such as masking tapes (for example, Patent Documents 1 and 2).
• Patent Document 1 relates to a pressure-sensitive adhesive composition that exhibits little increase in adhesive strength over time and leaves little adhesive residue after peeling, and includes a reactive surfactant and a non-reactive surfactant that do not contain an acrylic resin and an alkylene oxide chain. The technology to be used together is disclosed.
• Patent Document 2 relates to a removable water-based pressure-sensitive adhesive and a pressure-sensitive adhesive sheet that have good adhesion to a substrate and can obtain good removability even after being left in a high-temperature environment or a high-temperature and high-humidity environment.
• Disclosed is a technique of adding a citric acid ester to a removable water-based adhesive containing a polymer and a cross-linking agent.
• Patent Document 1 it is possible to suppress the increase in adhesive strength over time, and according to the configuration of Patent Document 2, it can be reused well even after being left in a high-temperature environment or a high-temperature and high-humidity environment.
• Patent Documents 1 and 2 discusses water-based paint resistance or solvent-based paint resistance with respect to the adhesive layer of the masking tape.
• Masking tapes generally use a paper substrate, and the topcoat applied on the masking tape permeates the paper substrate and reaches the adhesive layer formed on the surface of the paper substrate.
• the adhesive layer has poor resistance to water-based paints or solvent-based paints, there is a concern that the adhesive may remain on the surface of the mask object (hereinafter also referred to as "adhesive residue") when re-peeling.
• An object of the present invention is to provide a pressure-sensitive adhesive composition that has sufficient peel strength for use as a masking tape and that can provide a pressure-sensitive adhesive layer that is excellent in water-based paint resistance and solvent-based paint resistance.
• a pressure-sensitive adhesive composition comprising a copolymer (A), a cross-linking agent (B) and an aqueous medium,
• the copolymer (A) is at least one selected from the group consisting of (meth)acrylic acid alkyl esters having only one ethylenically unsaturated bond and hydrocarbons having only one ethylenically unsaturated bond.
• the copolymer (A) contains a structural unit derived from the silane coupling agent (a5), [1] to [6] The pressure-sensitive adhesive composition according to any one of [6].
• a method of manufacturing a masking tape comprising: forming. [10] A masking tape comprising a substrate and an adhesive layer formed on the substrate, A masking tape, wherein the adhesive layer comprises a cured product of the adhesive composition according to any one of [1] to [8]. [11] [10] A surface protection method comprising protecting the surface of an object to be masked using the masking tape described in [10].
• a set used for adjusting the adhesive composition containing a copolymer dispersion and a cross-linking agent (B),
• the copolymer dispersion contains a copolymer (A) and an aqueous medium
• the copolymer (A) is at least one selected from the group consisting of (meth)acrylic acid alkyl esters having only one ethylenically unsaturated bond and hydrocarbons having only one ethylenically unsaturated bond.
• the cross-linking agent (B) comprises a polyepoxy compound.
• a pressure-sensitive adhesive composition that has sufficient peel strength for use as a masking tape and that provides a pressure-sensitive adhesive layer that is excellent in water-based paint resistance and solvent-based paint resistance.
• the peel strength is defined as "the force generated by the contact between the adhesive surface of the masking tape and the adherend", and means the force required to peel off the pasted object.
• the holding power is defined as "the ability of the adhesive to withstand displacement when the masking tape is attached to the adherend and a static load is applied in the longitudinal direction", and the cohesive force of the adhesive layer. represents strength.
• (Meth)acrylic is a generic term for acrylic and methacrylic
• (meth)acrylate is a generic term for acrylate and methacrylate.
• Ethylenically unsaturated bond refers to an ethylenically unsaturated bond having radical polymerizability unless otherwise specified.
• a structural unit derived from a monomer having an ethylenically unsaturated bond is the chemical structure of the portion other than the ethylenically unsaturated bond of the monomer, and It has the same correspondence as the chemical structure other than the part corresponding to the ethylenically unsaturated bond of the unit.
• a structural unit derived from acrylic acid has a structure represented by —CH 2 CH(COOH)— in a polymer.
• a monomer from which a certain structural unit is derived refers to a compound having the above relationship with that structural unit, and does not need to match the monomer used in the actual manufacturing process.
• structural units having an ionic functional group such as a carboxyl group may or may not be partially ion-exchanged.
• a structural unit derived from an ionic compound For example, a structural unit represented by —CH 2 C(CH 3 )(COONa)— is also a structural unit derived from methacrylic acid.
• the ethylenically unsaturated bonds may remain as structural units of the polymer.
• a plurality of independent ethylenically unsaturated bonds refers to a plurality of ethylenically unsaturated bonds that do not form a conjugated diene with each other.
• the structural unit derived from divinylbenzene may be a structure having no ethylenically unsaturated bond (a form in which the portion corresponding to any ethylenically unsaturated bond is also incorporated into the polymer chain), and one A structure having an ethylenically unsaturated bond (a form in which only the portion corresponding to one ethylenically unsaturated bond is incorporated into the polymer chain) may be used.
• the chemical structure of the monomer and the chemical structure of the polymer do not correspond, such as chemically reacting the part other than the chain (-C-C-) corresponding to the ethylenically unsaturated bond after polymerization, the chemical structure after the reaction Based on structure.
• the saponified structural unit is considered to be a structural unit derived from vinyl alcohol, not a structural unit derived from vinyl acetate, based on the chemical structure of the polymer. do.
• Non-volatile content is the component remaining after weighing 1 g of the adhesive composition on an aluminum dish with a diameter of 5 cm and drying it at 105 ° C. for 1 hour while circulating air in a dryer at 1 atmosphere (1013 hPa). be.
• Forms of the adhesive composition include, but are not limited to, solutions, dispersions (emulsions), and slurries.
• Dispersion means a substance in which fine particles are uniformly and stably present in a dispersion medium without being dissolved in a solvent
• slurry means solid particles such as clay or pigment in a liquid means a suspended fluid.
• Non-volatile content concentration is the mass ratio (% by mass) of the non-volatile content after drying under the above conditions with respect to the mass (1 g) of the pressure-sensitive adhesive composition before drying.
• the term "adhesive” refers to a cured product of the adhesive composition, that is, an adhesive obtained by removing water from the adhesive composition and curing it (hereinafter simply referred to as “adhesive” (sometimes).
• the pressure-sensitive adhesive is obtained by drying the pressure-sensitive adhesive composition at 100° C. for 2 minutes and then curing it by standing at 40° C. for 3 days. It is believed that the curing (crosslinking) of the pressure-sensitive adhesive composition is completed while standing at 40° C. for 3 days.
• the term "adhesive composition coated layer” means a layer formed on a substrate or the like by removing an aqueous medium from the adhesive composition applied to the substrate or the like.
• the adhesive layer can be obtained by curing the adhesive composition coating layer.
• the pressure-sensitive adhesive layer is obtained by curing the pressure-sensitive adhesive composition coating layer by allowing it to stand at 40° C. for 3 days.
• the adhesive layer is a layer formed by curing an adhesive composition coating layer formed on a release paper after transferring to a substrate such as Japanese paper and curing at 40 ° C. for 3 days. good too.
• the pressure-sensitive adhesive composition according to the present embodiment is a pressure-sensitive adhesive composition containing a copolymer (A), a cross-linking agent (B), and an aqueous medium, and the pressure-sensitive adhesive composition contains other additives and the like. It may be
• the copolymer (A) is at least one selected from the group consisting of (meth)acrylic acid alkyl esters having only one ethylenically unsaturated bond and hydrocarbons having only one ethylenically unsaturated bond.
• a structural unit derived from the monomer (a1), a structural unit derived from the monomer (a2) having an ethylenically unsaturated bond and a carboxy group, and a monomer (a3) having an ethylenically unsaturated bond and a tertiary amino group contains structural units that
• the copolymer (A) contains at least one of a structural unit derived from a monomer (a4) described later and a structure derived from another compound (a5) such as a silane coupling agent or a chain transfer agent. is preferred, and both (a4) and (a5) are more preferred.
• the copolymer (A) may also contain a structural unit derived from another monomer (a5) that does not fall under any of the structural units derived from the monomers (a1) to (a4).
• Monomer (a1) is a monomer other than monomer (a2) and monomer (a3) described later, and monomer (a1) is a group consisting of (meth)acrylic acid alkyl ester and a hydrocarbon having an ethylenically unsaturated bond. including at least one selected from The monomer (a1) preferably contains a (meth)acrylic acid alkyl ester, and more preferably consists of a (meth)acrylic acid alkyl ester. Monomer (a1) has only one ethylenically unsaturated bond.
• the hydrocarbon having an ethylenically unsaturated bond does not have a carboxy group, a tertiary amino group, or an alkoxysilyl group.
• the monomer (a1) one type of compound may be used, or two or more types of compounds may be used.
• the (meth)acrylic acid alkyl ester is not limited to a specific one, and various types can be used.
• (meth)acrylic acid ester of; the alcohol component constituting the ester is a (meth)acrylic acid ester of a linear, branched or alicyclic alkyl group having 5 to 7 carbon atoms; the alcohol component constituting the ester has a carbon number of (meth)acrylic acid esters of 8 or more linear, branched or alicyclic alkyl groups; Specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (Meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth
• hydrocarbons having an ethylenically unsaturated bond examples include aromatic compounds having an ethylenically unsaturated bond such as styrene, ⁇ -methylstyrene, p-methylstyrene, ethylene, and fatty acids having an ethylenically unsaturated bond such as propylene. group hydrocarbon compounds and the like. From the viewpoint of the production cost of the copolymer (A) and the adhesive strength at room temperature, the hydrocarbon having an ethylenically unsaturated bond is preferably styrene, which readily generates radicals.
• the glass transition point of the copolymer (A) can be adjusted by the type and ratio of structural units derived from the monomer (a1).
• Structural units that lower the glass transition point of copolymer (A) include, but are not limited to, structural units derived from 2-ethylhexyl acrylate and structural units derived from butyl acrylate.
• Structural units that increase the glass transition point of the copolymer (A) include, but are not limited to, structural units derived from methyl methacrylate and structural units derived from styrene.
• Monomer (a2) is a compound having an ethylenically unsaturated bond and a carboxy group.
• the monomer (a2) include acrylic acid, methacrylic acid, crotonic acid, citraconic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, 2-carboxyethyl acrylate oligomer, 2-acryloyloxyethyl succinic acid, and the like.
• ⁇ , ⁇ -unsaturated mono- or dicarboxylic acids; and carboxy group-containing vinyl compounds such as monohydroxyethyl (meth)acrylate phthalate and monohydroxypropyl (meth)acrylate oxalate.
• Monomer (a2) preferably has only one ethylenically unsaturated bond.
• the copolymer (A) contains structural units derived from the monomer (a2) having an ethylenically unsaturated bond and a carboxyl group, the resistance to aqueous paints and solvent paints is improved. Although the reason why this effect is produced is not clear, the present inventors presume the following.
• a carboxy group in a structural unit derived from the monomer (a2) having an ethylenically unsaturated bond and a carboxy group, and a monomer having an ethylenically unsaturated bond and a tertiary amino group described later An ionic bond interaction is generated between the structural unit derived from a3) and the tertiary amino group, thereby increasing the strength of the adhesive layer. It is speculated that this increases the resistance to water-based paints and solvent-based paints.
• the carboxy group of the monomer (a2) reacts with the functional group of the cross-linking agent (B) described later to form a cross-link, and the adhesive layer is imparted with water resistance and solvent resistance. It is speculated that the resistance to
• the monomer (a2) is more preferably (meth)acrylic acid. Some or all of the carboxy groups of the monomer (a2) may form a salt.
• the salt formation rate is preferably 10% or less on a number (moles) basis.
• a monomer having a tertiary amino group in the present embodiment is a compound having an ethylenically unsaturated bond and a tertiary amino group.
• the tertiary amino group in the present embodiment means —NR 11 R 12 (wherein R 11 and R 12 are substituents other than hydrogen and may be different or the same. R 11 and R 12 is a functional group represented by ) which may combine with each other to form a ring.
• Monomer (a3) preferably has only one ethylenically unsaturated bond. Moreover, the monomer (a3) preferably has only one tertiary amino group.
• a monomer having at least one carboxy group and having at least one tertiary amino group corresponds to the monomer (a3) and does not correspond to the monomer (a2).
• Examples of the monomer (a3) having an ethylenically unsaturated bond and a tertiary amino group include 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, N-[2-(meth)acryloyloxyethyl]piperidine, N-[2-(meth)acryloyloxyethyl]pyrrolidine, N-[2-(meth)acryloyloxyethyl]morpholine (Meth) acrylic acid ester-based monomers; 4-(N,N-dimethylamino)styrene, 4-(N,N-diethylamino)styrene or 4-vinylpyridine; N-acryloyl heterocyclic monomers; (meth)acrylamide monomers such as 2-dimethylamino
• R 1 is a hydrogen atom or a methyl group
• R 2 and R 3 each independently represent an alkyl group having 1 to 3 carbon atoms
• Y 1 represents an alkylene group having 1 to 4 carbon atoms.
• 2-dimethylaminoethyl (meth) acrylate and 2-diethylaminoethyl (meth) acrylate from the viewpoint of emulsion polymerization stability and ease of control of physical properties as a pressure-sensitive adhesive composition for masking tapes.
• the copolymer (A) contains a structural unit derived from a monomer having a tertiary amino group, the above effects are obtained, but the present inventors speculate as follows.
• Japanese paper which is used as an example of a base material in a masking tape, which is one application of the pressure-sensitive adhesive composition, is a hydrophilic material containing cellulose as a main component. Therefore, due to the interaction with the copolymer containing the structural unit derived from the monomer having an ionic tertiary amino group, the adhesion between the adhesive and the base material such as paper base material is improved, and the water-based paint , it is speculated that the resistance to solvent paint is increased and the peel strength is improved. In addition, interaction with the carboxyl group described above is also considered as one theory.
• the monomer (a4) is a compound having an ethylenically unsaturated bond which does not fall under any of the structural units derived from the monomers (a1) to (a3).
• Examples of the monomer (a4) include vinyl ester compounds such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate; conjugated diolefin compounds such as butadiene, isoprene and chloroprene; amine imides such as 1,1,1-trimethylamine methacrylimide.
• vinyl cyanide compounds such as acrylonitrile and methacrylonitrile
• (meth)acrylamide compounds such as (meth)acrylamide
• 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole and radically polymerizable light stabilizers such as 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate; and the like.
• Other compounds (a5) include, for example, polymerization initiators, silane coupling agents, and chain transfer agents used in the step of synthesizing the copolymer (A).
• polymerization initiators for example, polymerization initiators, silane coupling agents, and chain transfer agents used in the step of synthesizing the copolymer (A).
• chain transfer agents used in the step of synthesizing the copolymer (A).
• the structure derived from the other compound (a5) in the copolymer (A) unlike the structural units derived from the monomers (a1) to (a4), it contains a polymerization initiator, a silane coupling agent, and a chain transfer agent.
• There may be no correspondence between the structure of the other compound such as and the structure derived from the other compound (a5) in the copolymer (A).
• a monomer having an alkoxysilyl group is preferable as the silane coupling agent, which is an example of the other compound (a5).
• Examples thereof include compounds having an alkoxysilyl group and one ethylenically unsaturated bond.
• the silane coupling agent preferably does not have multiple independent ethylenically unsaturated bonds.
• a monomer having an alkoxysilyl group a compound represented by the following general formula (2) is preferably exemplified.
• R 1 represents a methacryloxy group, an acryloxy group or a vinyl group
• R 2 to R 4 each independently represents an alkoxy group having 1 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms. and at least one of R 2 to R 4 is an alkoxy group having 1 to 20 carbon atoms.
• n represents an integer of 0-20. n is preferably 1-10, more preferably 1-5.
• the number of carbon atoms in the alkoxy group having 1 to 20 carbon atoms is preferably 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms, particularly preferably 1 or 2 carbon atoms.
• the number of carbon atoms in the alkyl group having 1 to 20 carbon atoms is preferably 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms, particularly preferably 1 or 2 carbon atoms.
• the alkoxy group having 1 to 20 carbon atoms includes methoxy, ethoxy, propoxy, butoxy, pentoxy, octoxy and the like.
• alkyl groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, A tetradecyl group, a hexadecyl group, an octadecyl group and the like can be mentioned.
• the monomer represented by formula (2) is preferably 3-methacryloxypropyltrimethoxysilane from the viewpoint of improving the cohesive strength of the adhesive.
• Examples of 3-methacryloxypropyltrimethoxysilane include "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.
• chain transfer agents examples include n-dodecylmercaptan, t-dodecylmercaptan, n-butylmercaptan, 2-ethylhexylthioglycolate, 2-mercaptoethanol, and ⁇ -mercaptopropionic acid. , methyl alcohol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, benzyl alcohol, and the like, but are not limited to these. Only one type of chain transfer agent may be used, or two or more types may be used.
• the emulsifier is not limited to a specific one.
• anionic surfactants such as sodium dodecylbenzenesulfonate and sodium dodecyl sulfate
• nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene nonylphenyl ethers, ceyltrimethylammonium bromide, and laurylpyridinium chloride.
• cationic surfactants such as laurylbedine, polyoxyethylene ether phosphate, and other reactive surfactants.
• amphoteric surfactants such as laurylbedine, polyoxyethylene ether phosphate, and other reactive surfactants.
• the content of structural units derived from compounds such as monomers and chain transfer agents in the copolymer (A) is calculated as a total of 100% by mass of the compounds from which the structural units are derived in the copolymer, Description will be made using the value of the content rate (mass %) of each compound.
• the copolymer (A) preferably contains a total of 90% by mass or more of structural units derived from the monomers (a1) to (a3), more preferably 95% by mass or more, and 97% by mass or more. More preferred. This is for suppressing an increase in the glass transition point of the copolymer (A) and improving the tackiness, wettability, and adhesion of the adhesive layer.
• the content of structural units derived from the monomer (a1) relative to the copolymer (A) is preferably 50% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. is more preferred. This is for improving the peel strength of the copolymer (A).
• the content of structural units derived from the monomer (a1) relative to the copolymer (A) is preferably 99.99% by mass or less, more preferably 99.95% by mass or less, and 99.90% by mass. % by mass or less is more preferable. This is for improving the holding power of the copolymer (A).
• the content of structural units derived from the monomer (a2) relative to the copolymer (A) is preferably 0.010% by mass or more, more preferably 0.050% by mass or more, and 0.500% by mass or more. % or more is more preferable. This is to improve the reactivity with the cross-linking agent and enhance the resistance to water-based paints and solvent-based paints.
• the content of structural units derived from the monomer (a2) relative to the copolymer (A) is preferably 8.0% by mass or less, more preferably 5.0% by mass or less, and 4.0% by mass. % or less is most preferable. This is because the resistance to water-based paints and solvent-based paints can be enhanced, and harmony with peel strength can be obtained. Moreover, it may be 3.5% by mass or less, 2.5% by mass or less, or 2.0% by mass or less.
• the content of the structural unit derived from the monomer (a3) relative to the copolymer (A) is preferably 0.010% by mass or more, more preferably 0.050% by mass or more, and 0.100% by mass or more. % or more is more preferable. It improves the interaction by ionic bonds with the monomer (a2) having an ethylenically unsaturated bond and a carboxy group, and the interaction with substrates such as paper substrates, and increases resistance to water-based paints and solvent-based paints. This is because harmony with strength can be obtained.
• the content of structural units derived from the monomer (a3) relative to the copolymer (A) is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and 2.5% by mass. % by mass or less is more preferable. It improves the interaction by ionic bonds with the monomer (a2) having an ethylenically unsaturated bond and a carboxy group, and the interaction with substrates such as paper substrates, and increases resistance to water-based paints and solvent-based paints. This is because harmony with strength can be obtained. Moreover, it may be 1.9% by mass or less, 1.0% by mass or less, or 0.60% by mass or less.
• the content of the structural unit derived from the silane coupling agent, which is the other compound (a5), relative to the copolymer (A) is preferably 0.500% by mass or less, and is 0.300% by mass or less. is more preferably 0.200% by mass or less, and particularly preferably 0.100% by mass or less. This is for improving the peel strength and the holding power of the adhesive layer, in addition to the resistance to water-based paints and solvent-based paints. From the viewpoint of resistance to water-based paint, the content is preferably 0.000% by mass or more, more preferably 0.010% by mass or more, and even more preferably 0.050% by mass or more.
• the silane coupling agent one type of compound may be used, or two or more types of compounds may be used.
• the content of the structural unit derived from the chain transfer agent, which is the other compound (a5), relative to the copolymer (A) is preferably 0.200% by mass or less, and is 0.100% by mass or less. is more preferably 0.050% by mass or less, and particularly preferably 0.035% by mass or less. This is for improving the peel strength and the holding power of the adhesive layer. From the viewpoint of peel strength, the content is preferably 0.000% by mass or more, more preferably 0.010% by mass or more, and even more preferably 0.020% by mass or more.
• the method for producing the copolymer (A) is not particularly limited, but a monomer from which each structural unit constituting the copolymer (A) is derived may be polymerized as a monomer, and some or all of the structural units may be , and other monomers may be polymerized and then functional groups may be introduced to form the desired structural units.
• Examples of the method for producing the copolymer (A) include a method of emulsifying a monomer in an aqueous medium and subjecting it to emulsion polymerization using a polymerization initiator. In polymerization, a chain transfer agent may be used to control the molecular weight of the copolymer and its distribution within an appropriate range.
• Emulsifiers may be used to emulsify the monomers.
• the total amount of the monomers may be charged in advance to the reactor, and in order to obtain uniform particles, a mixture containing all kinds of monomers for forming the structural units of the copolymer (A) is continuously or intermittently added.
• Polymerization may be carried out while supplying and charging.
• the polymerization temperature is not particularly limited, it is preferably 5 to 100°C, more preferably 50 to 90°C.
• the aqueous medium is water, a hydrophilic solvent, or a mixture thereof.
• Hydrophilic solvents include methanol, ethanol, isopropyl alcohol, N-methylpyrrolidone, and the like.
• the aqueous medium is preferably water.
• water to which a hydrophilic solvent is added may be used as long as the polymerization stability is not impaired.
• Polymerization initiators used in emulsion polymerization include persulfate-based initiators such as potassium persulfate, ammonium persulfate and sodium persulfate; organic peroxides such as t-butyl hydroperoxide and cumene hydroperoxide; and hydrogen peroxide. These polymerization initiators may be used alone or in combination.
• the amount of polymerization initiator to be used is preferably 0.1 to 2% by mass with respect to the total amount of monomers.
• a reducing agent can be used together with these polymerization initiators.
• reducing agents include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate metal salts, and reducing agents such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite. Examples include inorganic compounds.
• the cross-linking agent (B) contains a polyepoxy compound.
• a polyepoxy compound means a compound having two or more epoxy groups. Note that the epoxy group may be part of the glycidyl group.
• the cross-linking agent (B) may be a carbodiimide compound having an epoxy group.
• the polyepoxy compound, which is the cross-linking agent (B) preferably does not contain a silicon-containing functional group such as an alkoxysilyl group or a phenoxysilyl group.
• a polyepoxy compound is preferable from the viewpoint of being able to impart higher adhesive strength and cohesive strength to the pressure-sensitive adhesive at room temperature and high temperature.
• the cross-linking agent (B) is preferably a water-soluble or water-dispersible compound.
• the polyepoxy compound may be used alone or in combination of two or more.
• a known compound can be used together as the cross-linking agent (B) as long as the effects of the present application are exhibited.
• a polyepoxy compound and a compound other than the polyepoxy compound may be used together.
• Polyepoxy compounds include, for example, bisphenol A/epichlorohydrin type epoxy resins, sorbitol polyglycidyl ether (for example, "Denacol (registered trademark, hereinafter the same) EX-611" and “Denacol EX-612” manufactured by Nagase ChemteX Corporation. , "Denacol EX-614", “Denacol EX-614B”, “Denacol EX-622”, etc.), polyglycerol polyglycidyl ether (e.g., "Denacol EX-512", “Denacol EX-521” manufactured by Nagase ChemteX Co., Ltd.
• pentaerythritol polyglycidyl ether eg, “Denacol EX-411” manufactured by Nagase ChemteX Corporation
• diglycerol polyglycidyl ether eg, “Denacol EX-421” manufactured by Nagase ChemteX Corporation
• Glycerol polyglycidyl ether eg, "Denacol EX-313", “Denacol EX-314", etc.
• ethylene glycol diglycidyl ether e.g. Nagase ChemteX Co., Ltd. “Denacol EX-810”, “Denacol EX-811” etc.
• diethylene glycol diglycidyl ether e.g. Nagase ChemteX Co., Ltd.
• the epoxy equivalent (molecular weight per epoxy group) of the polyepoxy compound is preferably 70 or more, more preferably 80 or more, and even more preferably 100 or more. This is to suppress steric hindrance in the cross-linking reaction with the copolymer (A) when curing the pressure-sensitive adhesive composition, and to improve the speed of the cross-linking reaction and the cross-linking density.
• the epoxy equivalent (molecular weight per epoxy group) of the polyepoxy compound is preferably 700 or less, more preferably 400 or less, still more preferably 300 or less, and 200 or less. Especially preferred. This is to improve the crosslink density in the crosslink reaction with the copolymer (A).
• cross-linking agents known cross-linking agents can be used together.
• the content of the cross-linking agent (B) with respect to 100 parts by mass of the copolymer (A) in the adhesive composition is preferably 0.010 parts by mass or more, more preferably 0.020 parts by mass or more, It is more preferably 0.050 parts by mass or more, particularly preferably 0.15 parts by mass or more, and most preferably 0.40 parts by mass or more. This is because the crosslink density between particles is increased, the cohesive force and water resistance of the adhesive obtained from the adhesive composition are improved, and the resistance to water-based paint and solvent paint is improved.
• the content of the cross-linking agent (B) in the adhesive composition is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, relative to 100 parts by mass of the copolymer (A). It is more preferably 0 parts by mass or less. It is because it becomes moderate peeling strength. Moreover, the content of the cross-linking agent (B) may be 3.0 parts by mass or less, or may be 1.5 parts by mass or less, from the viewpoint of improving the 40° C. holding power.
• Aqueous medium are water, hydrophilic solvents, or mixtures thereof.
• Hydrophilic solvents include methanol, ethanol, isopropyl alcohol, N-methylpyrrolidone, and the like.
• the aqueous medium is water.
• the aqueous medium may have the same composition as the aqueous solvent used for polymerization of the copolymer (A), or may have a different composition.
• Additives can be included in the pressure-sensitive adhesive composition as appropriate.
• the timing of adding the additive is not particularly limited.
• the additive can be added at the same time as or after mixing the copolymer (A) and the cross-linking agent (B).
• the additive may be added to either or both solutions or dispersions in advance before mixing the copolymer (A) and the cross-linking agent (B).
• Examples of additives include pH adjusters and tackifiers.
• plasticizers, antioxidants, fillers, pigments, colorants, wetting agents, antifoaming agents, thickeners, etc. can be used as appropriate.
• Organic acid pH adjusters include, for example, acetic acid, formic acid, glycolic acid, malic acid, citric acid, maleic acid, fumaric acid, malonic acid, phthalic acid, isophthalic acid, lactic acid, butyric acid, ascorbic acid, succinic acid, and tartaric acid. , acrylic acid, methacrylic acid, crotonic acid, adipic acid, oxalic acid, abietic acid and the like.
• inorganic acid pH adjusters include boric acid, phosphoric acid, hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, and sulfurous acid.
• salts of acidic substances include salts of the above organic acids or inorganic acids with sodium, potassium, ammonia, aminoethanol, diethanolamine and triethanolamine.
• amino acid pH adjusters include glycine, glycylglycine, asparagine, aspartic acid, alanine, phenylalanine, arginine, glutamine, and glutamic acid. These pH adjusters can be used alone or in combination of two or more.
• tackifiers include rosin resins, rosin ester resins, hydrogenated rosin resins, polymerized rosin resins, ⁇ -pinene resins, ⁇ -pinene resins, terpene phenol resins, C5 fraction petroleum resins, and C9 fraction petroleum resins. resins, C5 fraction/C9 fraction petroleum resins, dicyclopentadiene petroleum resins, alkylphenol resins, xylene resins, coumarone resins, coumarone-indene resins, and the like.
• a tackifier can be used individually or in combination of 2 or more types.
• the non-volatile content concentration of the pressure-sensitive adhesive composition is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. This is because a larger amount of adhesive layer can be formed with a smaller coating amount of the adhesive composition. Moreover, it is because the drying time of the applied pressure-sensitive adhesive composition is shortened and the productivity is improved.
• the non-volatile content concentration of the pressure-sensitive adhesive composition is preferably 75% by mass or less, more preferably 65% by mass or less. This is for suppressing gelation of the copolymer (A) in the pressure-sensitive adhesive composition.
• the total content of the copolymer (A) and the cross-linking agent (B) in the nonvolatile matter is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass. % or more is more preferable. This is because the adhesive strength and holding power of the adhesive layer, especially at high temperatures, are improved.
• the total content of the copolymer (A) and the cross-linking agent (B) in the non-volatile matter in the adhesive composition is preferably 90% by mass or less, more preferably 80% by mass or less.
• the pressure-sensitive adhesive composition of the present embodiment is a multi-agent set in which the constituent components of the pressure-sensitive adhesive composition are divided into a plurality of additives so that the pressure-sensitive adhesive composition is obtained by mixing a plurality of additive liquids.
• the copolymer dispersion and the cross-linking agent for adjusting the adhesive composition obtained by mixing the copolymer dispersion containing the copolymer (A) and an aqueous medium with the cross-linking agent (B).
• a set including (B) may be prepared, and the adhesive composition may be adjusted by mixing the copolymer dispersion and the cross-linking agent (B) when using the adhesive composition.
• Masking tapes are typical uses of the pressure-sensitive adhesive composition of the present invention.
• the concept of "masking tape” herein may include what is referred to as a "masking sheet.”
• a masking tape according to this embodiment includes a substrate and an adhesive layer formed on the substrate.
• the adhesive layer on the side opposite to the substrate may be protected with a known release liner such as release paper or release PET.
• the material of the base material is not particularly limited, and non-woven fabric, paper, cloth, plastic film with numerous fine through holes formed by a hot fusion perforation method, metal, etc. can be mentioned, but paper is more preferable. This is because when the masking tape is produced, the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer permeates into the paper substrate, increasing the bonding strength between the pressure-sensitive adhesive layer and the substrate.
• the paper substrate can be crepe paper, Japanese paper, kraft paper, glassine paper, fine paper, synthetic paper, top-coated paper, and the like.
• crepe paper or Japanese paper that can be commonly used as a substrate for masking tapes.
• Japanese paper can be made from beaten wood pulp or blended with one or more synthetic staple fibers. Synthetic short fiber materials include, for example, vinylon, nylon, polyester, polypropylene, and polyvinyl chloride.
• the thickness of the substrate can be, for example, 20-800 ⁇ m, typically 30-450 ⁇ m. A more preferable thickness may vary depending on the type of substrate.
• the thickness can be, for example, 300 ⁇ m or less, usually 200 ⁇ m or less, preferably 150 ⁇ m or less, more preferably 100 ⁇ m or less.
• the thickness of the Japanese paper can be, for example, 20 ⁇ m or more, usually 30 ⁇ m or more, preferably 40 ⁇ m or more, more preferably 50 ⁇ m or more.
• the base material may further contain additives such as general resin materials, fillers, and colorants that can be used in adhesive sheet or masking tape base materials.
• additives such as general resin materials, fillers, and colorants that can be used in adhesive sheet or masking tape base materials.
• the paper substrate may be impregnated with the additives described above.
• the substrate may be surface-treated on one side or both sides.
• the "base material" in the present invention is the part that is attached to the adherend together with the adhesive layer when the masking tape of the present invention is used, that is, adhered, to the adherend (also referred to as the masking object). It does not include release liners such as release papers that are released when the tape is used.
• the adhesive layer contains an adhesive that is a cured product of the adhesive composition.
• the adhesive layer may contain additives and the like in addition to the adhesive.
• the adhesive layer contains the non-volatile matter of the adhesive composition.
• the thickness of the adhesive layer is preferably 10 ⁇ m or more, more preferably 15 ⁇ m or more. and more preferably 18 ⁇ m or more. This is because the adhesive layer can be sufficiently deformed to conform to the surface of the adherend.
• the thickness of the adhesive layer is preferably 200 ⁇ m or less, more preferably 100 ⁇ m or less, and even more preferably 50 ⁇ m or less. This is for suppressing cohesive failure of the adhesive layer.
• the adhesive layer may comprise two or more adhesive layers.
• the masking tape of the present invention may comprise other layers (for example, an intermediate layer, an undercoat layer, etc.) in addition to the substrate and the adhesive layer within a range that does not impair the effects of the invention.
• a method for producing a masking tape includes a step of applying an adhesive composition to a substrate, and removing an aqueous medium from the adhesive composition applied to the substrate to form an adhesive composition coating layer. and curing the material coating layer to form an adhesive layer.
• An aqueous medium, a thickener, or the like may be appropriately added to the adhesive composition in order to adjust the viscosity of the adhesive composition upon application.
• the pressure-sensitive adhesive composition may be applied to the substrate continuously or intermittently.
• the coating amount of the pressure-sensitive adhesive composition is not particularly limited, it is preferably 10 to 500 g/m 2 .
• the drying temperature of the pressure-sensitive adhesive composition applied to the substrate is not particularly limited, it is preferably 20 to 160°C. This is because an adhesive layer having sufficient adhesive strength and cohesive strength can be obtained.
• the adhesive composition applied to the substrate is dried at 100°C for 2 minutes, the aqueous medium is removed to form the adhesive composition coating layer, and then the adhesive composition is dried at 40°C. It is preferable to allow the pressure-sensitive adhesive composition to stand still for 3 days to cure.
• masking tapes have been described as one of the preferred uses of the pressure-sensitive adhesive composition of the present invention, but the use of the pressure-sensitive adhesive composition of the present invention is not limited to this.
• the masking tape and the surface protection method characterized by protecting the surface of the object to be masked using the masking tape are used, for example, in electrical products, automobiles, construction members, toys, and the like.
• plastic members such as polypropylene, and metal members such as SUS and aluminum are particularly useful.
• Example 1 Into a polymerization apparatus equipped with a stirrer, a thermometer and a reflux condenser, 180 parts by mass of deionized water was introduced, and after sufficient nitrogen substitution, the temperature was raised. While maintaining the internal temperature at 75 ° C., 250 parts by mass of deionized water, 5 parts by mass of Adekari Soap SR-10 (manufactured by ADEKA Co., Ltd.) as an emulsifier, and 5 mass parts of Adekari Soap PP-70 (manufactured by ADEKA Co., Ltd.) as an emulsifier.
• Adekari Soap SR-10 manufactured by ADEKA Co., Ltd.
• Adekari Soap PP-70 manufactured by ADEKA Co., Ltd.
• ammonium persulfate was added as a polymerization initiator to initiate polymerization, and the mixture was reacted at 80° C. for 15 minutes. Further, the remaining 97 mass % of the previous emulsion and 25 mass parts of a 5 mass % ammonium persulfate aqueous solution were added over 3 hours while maintaining the internal temperature at 80°C. Furthermore, it was made to react at 80 degreeC for 2 hours.
• a copolymer dispersion containing The properties of the obtained copolymer dispersion are: non-volatile content 53.2% by mass, viscosity 8000 mPa s (BH type viscometer, 10 rpm, 23° C.), pH 8.5 (pH meter "HM-30G", manufactured by Toa DKK Co., Ltd.; 23°C).
• the type and content (parts by mass) of the cross-linking agent (B) shown in Table 1-1 were added to 100 parts by mass of the copolymer (A) to obtain a pressure-sensitive adhesive composition.
• Table 1-1 shows the content (% by mass) of each structural unit when converted to 100% by mass of the total of (a1) to (a5), which are the structural units or the compounds from which the structure is derived, in the copolymer. show.
• the content of the cross-linking agent (B) in the pressure-sensitive adhesive composition is "the content of the cross-linking agent (B) with respect to 100 parts by mass of the copolymer (A) in the pressure-sensitive adhesive composition (parts by mass )” means.
• Examples 2-8) PSA compositions of Examples 2 to 8 were obtained in the same manner as in Example 1 except that each formulation shown in Table 1-1 was used.
• Examples 9-15 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that each formulation shown in Table 1-2 was used.
• ⁇ Preparation of masking tape> The adhesive compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 3 were applied to Japanese paper (A4 size, thickness 60 ⁇ m). A doctor blade with a coating width of 15 cm was used as an applicator. The applied pressure-sensitive adhesive composition was dried at 100° C. for 2 minutes, the aqueous medium was removed from the pressure-sensitive adhesive composition, and a pressure-sensitive adhesive composition coating layer having a thickness of 20 ⁇ m was formed on Japanese paper. A release surface of a release paper (coated with silicone) was pasted onto the pressure-sensitive adhesive composition-coated layer on Japanese paper. The adhered pressure-sensitive adhesive composition coating layer was aged at 40° C. for 3 days to form a pressure-sensitive adhesive layer (thickness: 20 mm). In this way, a masking tape comprising a base material, an adhesive layer formed on the base material, and a release paper attached thereto was obtained.
• the masking tape was applied in excess of the usual paint amount and tested. Two hours after the application, the masking tape was peeled off, and the surface of the hard vinyl chloride plate after peeling was observed to visually confirm the presence or absence of contamination and adhesive residue.
• Solvent paint (Lacquer Spray SL (manufactured by Dainippon Co., Ltd.) was spray-coated on the entire surface of a tin plate (thickness: 0.3 mm) so that the thickness of the coating film was uniform (coating amount: 20 g/m 2 ). It was allowed to dry for 1 minute to form the undercoated surface. Thereafter, the release paper of the masking tape cut into a tape width of 15 mm and length of 100 mm was peeled off from the entire surface, and the masking tape was pasted from the adhesive layer side to the tin plate having the undercoated surface. After sticking, a 2 kg roller was reciprocated once in an atmosphere of 23°C.
• Lacquer Spray SL was further spray-coated on the entire surface of the laminated masking tape so that the thickness of the coating film was uniform (coating amount: 2000 g/m 2 ).
• the masking tape was applied in excess of the usual paint amount and tested. Two hours after application, the masking tape was peeled off, and the undercoated surface after peeling was observed to visually confirm the presence or absence of contamination and adhesive residue.
• solvent paint resistance evaluation criteria ⁇ No contamination or adhesive residue on the undercoated surface. ⁇ ⁇ Slightly contaminated undercoated surface with adhesive residue. ⁇ ⁇ The undercoat paint surface is completely contaminated, and there is adhesive residue.
• the test is a so-called 180° peel test.
• the masking tape of the evaluation sample was folded back 180° at the boundary between the portion adhered to the SUS plate and the portion not adhered.
• One end of the masking tape to which the SUS plate was not attached was gripped with an upper chuck of a tester (Tensilon RTG-1210 (manufactured by A&D Co., Ltd.)).
• One end of the SUS plate facing the upper chuck across the folding line was gripped by the lower chuck.
• peel strength evaluation criteria ⁇ 1.0 or more, ⁇ ⁇ 0.7 or more and less than 1.0, ⁇ Less than 0.7
• the bonding was performed by reciprocating a 2 kg roller once under an atmosphere of 23°C. Also, at this time, a portion of the SUS plate alone, to which the masking tape was not attached, was provided as an SUS plate-side chuck portion on the extension of one end of the masking tape attached to the SUS plate.
• the evaluation sample was left in a constant temperature bath at 40° C. for 30 minutes. After that, in a constant temperature bath at 40 ° C., using a tester (holding force tester (manufactured by Tester Sangyo Co., Ltd.)), the SUS plate side chuck part of the evaluation sample is gripped with the upper chuck of the tester, masking tape A weight of 1000 g was suspended at one end in the longitudinal direction on the side where the SUS plate was not bonded, and left for 5 hours. After that, it was evaluated whether the masking tape completely peeled off from the SUS plate. Evaluation results are as shown in Tables 3 and 4. 40 ° C. holding power evaluation criteria; ⁇ ⁇ Not dropped for 5 hours or more, ⁇ ⁇ Falls in 1 hour or more and less than 5 hours, ⁇ Drop within 1 hour.
• the masking tape according to Comparative Example 1 which was produced using the pressure-sensitive adhesive composition that did not contain the cross-linking agent (B), had insufficient resistance to both water-based paint and solvent-based paint.
• the masking tape according to Comparative Example 2 which was created using the adhesive composition that did not contain the monomer (a2) having an ethylenically unsaturated bond and a carboxyl group, had insufficient resistance to water-based paint.
• the masking tape according to Comparative Example 3 which was prepared using the adhesive composition that did not contain the monomer (a3) having an ethylenically unsaturated bond and a tertiary amino group, exhibited resistance to water-based paints and solvent-based paints. Both are inadequate, and it can be seen that the object of the present invention cannot be achieved.
• a pressure-sensitive adhesive composition capable of forming an adhesive layer having not only resistance to water-based paints and solvent-based paints but also sufficient peel strength necessary for use as a masking tape.

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• 2022
  • 2022-11-28 WO PCT/JP2022/043777 patent/WO2023120049A1/ja not_active Ceased
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  • 2022-11-28 JP JP2023569208A patent/JPWO2023120049A1/ja active Pending

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