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
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/06—Non-macromolecular additives organic
• • 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
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/08—Macromolecular additives
• • 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
  • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16

Definitions

• the present invention relates to an ultraviolet-curable adhesive composition.
• the present invention also relates to a method for producing a laminate using the ultraviolet-curable adhesive composition.
• Adhesives are used to bond electronic components inside electronic devices such as smartphones and PCs.
• an adhesive sheet is first prepared with separators on both sides of the adhesive, and then the adhesive sheet is cut into the desired shape.
• One separator is then peeled off from the cut adhesive sheet, and one side of the exposed adhesive is bonded to a first adherend, and then the other separator is peeled off, and the other side of the exposed adhesive is bonded to a second adherend.
• part of the adhesive sheet is discarded after cutting, resulting in waste.
• Patent Document 1 discloses an invention for providing a radiation-curable adhesive composition that allows fine patterning and exhibits high adhesion to various adherends such as metals and plastics.
• Patent Document 1 describes a radiation-curable adhesive composition that contains 10 to 70% by weight of an ethylenically unsaturated monomer that does not contain an aromatic ring, 1 to 10% by weight of a photopolymerization initiator, and 10 to 55% by weight of a crosslinking agent.
• Patent Document 2 discloses an invention for providing a photocurable adhesive composition that, even when irradiated with light in the presence of oxygen, gives a laminate having adhesive strength equivalent to that in the absence of oxygen.
• Patent Document 2 describes a photocurable adhesive composition that contains (A) a (meth)acrylate oligomer, (B) a monofunctional (meth)acrylic monomer, (C) a di- to tetrafunctional (meth)acrylic monomer, (D) a photoinitiator, (E) a tackifier having a softening point of 70 to 150°C, and (F) a liquid plasticizer.
• Tape is used to fix the housing of an electronic device, and the tape must be applied without gaps to prevent liquids and dust from entering the inside of the device.
• the area of the inner squares becomes waste as it is.
• there is a method of forming a square shape by combining multiple rectangular or L-shaped tapes but it is difficult to fill the gaps between the tapes when applying them, and there is a problem that liquids and dust enter through the gaps.
• the generation of waste can be suppressed by the method of printing the adhesive composition in a desired shape and then laminating it to the adherend without preparing an adhesive sheet.
• ultraviolet curing is desirable to avoid heating the adherend, but in the conventional adhesive composition, in order to achieve both reactivity to ultraviolet rays and adhesive properties, the amount of oxygen on the surface is reduced by placing it in a nitrogen atmosphere or laminating a film, and then the composition is cured by irradiating it with low-illuminance ultraviolet rays to a high accumulated light amount. Therefore, there are restrictions on equipment and production speed. In addition, there has been a problem in that the dimensions and shape of the adhesive composition may change after printing due to contact of the film with the uncured adhesive composition or application of heat in the drying process after printing.
• the present invention aims to provide an ultraviolet-curable adhesive composition that has excellent ultraviolet curability in the presence of oxygen, waterproofness and dust resistance, and shape stability after printing, as well as an ultraviolet-curable adhesive composition that has excellent curability when irradiated with high-intensity ultraviolet light in the presence of oxygen, and excellent adhesion and retention performance after curing.
• the present invention also aims to provide a method for producing a laminate using the ultraviolet-curable adhesive composition.
• Disclosure 1 relates to an ultraviolet-curable pressure-sensitive adhesive composition for use in printing, the ultraviolet-curable pressure-sensitive adhesive composition comprising a radical polymerizable monomer, a photopolymerization initiator, and a thickener, the radical polymerizable monomer comprising a compound having a cyclic structure containing a nitrogen atom, and having a viscosity of 3 Pa ⁇ s or more and 100 Pa ⁇ s or less as measured using an E-type viscometer at 25°C and 10 rpm.
• Disclosure 2 relates to the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1, which is obtained by coating the ultraviolet-curable pressure-sensitive adhesive composition on a substrate, irradiating the coated surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 at an irradiation dose of 3000 mJ/ cm2 under an atmospheric environment, without sealing the coated surface, to obtain a cured product having a thickness of 50 ⁇ m, the reaction rate of which is 90% or more.
• the present disclosure 3 is the ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1 or 2, wherein the compound having a cyclic structure containing a nitrogen atom includes at least one selected from the group consisting of radical polymerizable monomers having a lactam structure and maleimide derivatives.
• Disclosure 4 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 3, wherein the compound having a cyclic structure containing a nitrogen atom comprises the maleimide derivative, and the maleimide derivative has at least a content of a maleimide derivative not having a structure in which hydrogen is bonded to a heteroatom of 50 mass% or more, or a content of a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom of 10 parts by mass or less relative to 100 parts by mass of the radical polymerizable monomer, and the content of the maleimide derivative in 100 parts by mass of the radical polymerizable monomer is 0.1 part by mass or more and 20 parts by mass or less.
• the present disclosure 5 is the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 3, wherein the compound having a cyclic structure containing a nitrogen atom comprises the radical polymerizable monomer having the lactam structure, and the content of the radical polymerizable monomer having the lactam structure in 100 parts by mass of the radical polymerizable monomer is 10 parts by mass or more and 60 parts by mass or less.
• the present disclosure 6 is the ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, or 5, wherein the radical polymerizable monomer contains 20 mass% or more of a monomer capable of serving as a hydrogen donor, the photopolymerization initiator contains at least one selected from the group consisting of a hydrogen abstraction type photopolymerization initiator and a polymer type photopolymerization initiator, the ultraviolet-curable pressure-sensitive adhesive composition further contains an amine compound, the amine compound contains an amine compound having no structure in which hydrogen is bonded to a heteroatom in the amine compound in an amount of 50 mass% or more, and the content of the amine compound is 0.1 parts by mass or more and 10 parts by mass or less in a total of 100 parts by mass of the ultraviolet-curable pressure-sensitive adhesive composition excluding the photopolymerization initiator.
• the radical polymerizable monomer contains 20 mass% or more of a monomer capable of serving as a hydrogen donor
• the photopolymerization initiator contains at least one selected
• the present disclosure 7 is the ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, or 6, wherein the radical polymerizable monomer comprises a polyfunctional (meth)acrylic monomer.
• the present disclosure 8 is the ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the thickener comprises at least one selected from the group consisting of a thermoplastic resin, a polymeric thixotropy regulator, and a solid thickener.
• the present disclosure 9 is the ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 8, wherein the thickener contains the thermoplastic resin, and the thermoplastic resin contains a (meth)acrylic copolymer.
• the present disclosure 10 is an ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, which is obtained by applying the ultraviolet-curable pressure-sensitive adhesive composition to a substrate, and irradiating the applied surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 at an exposure dose of 3000 mJ/cm2 under an atmospheric environment, and which has a thickness of 50 ⁇ m and a glass transition temperature of ⁇ 40° C. or higher and 20° C. or lower.
• the present disclosure 11 is an ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, which is obtained by coating the ultraviolet-curable pressure-sensitive adhesive composition on a substrate, irradiating the coated surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 under an atmospheric environment without sealing the coated surface, so that the irradiation amount is 3000 mJ/ cm2 , and obtaining a cured product having a thickness of 50 ⁇ m, the gel fraction of which is 20 mass% or more and 80 mass% or less.
• Disclosure 12 is an ultraviolet-curable pressure-sensitive adhesive composition
• a monofunctional radical polymerizable monomer comprising a photopolymerization initiator, and a crosslinking agent having two or more reactive functional groups in one molecule
• the monofunctional radical polymerizable monomer comprising a compound having a cyclic structure containing a nitrogen atom
• the ultraviolet-curable pressure-sensitive adhesive composition being coated on a substrate, and the coated surface being unsealed and irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 in an atmospheric environment at an irradiation dose of 3000 mJ/cm 2 to obtain a cured product having a thickness of 50 ⁇ m, the cured product having a reaction rate of 90% or more, the cured product having a gel fraction of 20% by mass or more and 80% by mass or less, and the cured product being subjected to dynamic viscoelasticity measurement under conditions of a shear method, a measurement temperature of
• the present disclosure 13 relates to the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 12, wherein the compound having a cyclic structure containing a nitrogen atom includes at least one selected from the group consisting of monofunctional radically polymerizable monomers having a lactam structure and maleimide derivatives.
• Disclosure 14 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 13, wherein the compound having a cyclic structure containing a nitrogen atom includes the maleimide derivative, and the maleimide derivative has at least a content of a maleimide derivative not having a structure in which hydrogen is bonded to a heteroatom of 50 mass% or more, or a content of a maleimide derivative having a structure in which hydrogen is bonded to a heteroatom of 10 parts by mass or less relative to 100 parts by mass of the monofunctional radical polymerizable monomer, and the content of the maleimide derivative in 100 parts by mass of the monofunctional radical polymerizable monomer is 0.1 parts by mass or more and 20 parts by mass or less.
• Disclosure 15 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 13, wherein the compound having a cyclic structure containing a nitrogen atom comprises a monofunctional radical polymerizable monomer having the lactam structure, and the content of the monofunctional radical polymerizable monomer having the lactam structure in 100 parts by mass of the monofunctional radical polymerizable monomer is 10 parts by mass or more and 60 parts by mass or less.
• the present disclosure 16 is an ultraviolet-curable pressure-sensitive adhesive composition according to the present disclosure 12, 13, 14, or 15, wherein the monofunctional radical polymerizable monomer contains 20 mass% or more of a monomer capable of serving as a hydrogen donor, the photopolymerization initiator contains at least one selected from the group consisting of a hydrogen abstraction type photopolymerization initiator and a polymer type photopolymerization initiator, the ultraviolet-curable pressure-sensitive adhesive composition further contains an amine compound, the amine compound contains an amine compound having no structure in which hydrogen is bonded to a heteroatom in the amine compound in an amount of 50 mass% or more, and the content of the amine compound is 0.5 parts by mass or more and 8.0 parts by mass or less in a total of 100 parts by mass of the ultraviolet-curable pressure-sensitive adhesive composition excluding the photopolymerization initiator.
• the monofunctional radical polymerizable monomer contains 20 mass% or more of a monomer capable of serving as a hydrogen donor
• the photopolymerization initiator contains
• Disclosure 17 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 16, wherein the monomer capable of serving as the hydrogen donor is a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the present disclosure 18 is the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 17, wherein the monofunctional radically polymerizable monomer contains 30 mass% or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• Disclosure 19 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 12, 13, 14, 15, 16, 17, or 18, wherein the crosslinking agent has, as the reactive functional group, two or more of at least one selected from the group consisting of an isocyanate group, an epoxy group, an aldehyde group, a hydroxyl group, an amino group, a (meth)acryloyl group, and a vinyl group in one molecule.
• the present disclosure 20 is the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 12, 13, 14, 15, 16, 17, 18, or 19, further comprising a thickener.
• Disclosure 21 is the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 20, wherein the thickener is at least one selected from the group consisting of a thermoplastic resin, a polymeric thixotropy regulator, and a solid thickener.
• the present disclosure 22 is the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21, further containing a tackifier.
• the present disclosure 23 is the ultraviolet-curable pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22, further containing an antifoaming agent.
• Disclosure 24 is a method for producing a laminate in which the ultraviolet-curable pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23 is applied onto a first adherend and exposed to light to form an adhesive layer, and a step of attaching a second adherend onto the adhesive layer, wherein the method for applying the ultraviolet-curable pressure-sensitive adhesive composition is screen printing, stencil printing, or reverse offset printing, and the ultraviolet-curable pressure-sensitive adhesive composition is applied entirely or partially onto the first adherend.
• the present disclosure 25 is a method for producing a laminate according to the present disclosure 24, wherein the first adherend and the second adherend are release-treated substrates.
• the present disclosure 26 is a method for producing a laminate according to the present disclosure 25, wherein the first adherend and the second adherend are base materials that have been subjected to a release treatment and an antistatic treatment.
• the present disclosure 27 is a method for producing a laminate according to the present disclosure 24, 25, or 26, in which the ultraviolet-curable pressure-sensitive adhesive composition is partially coated on the first adherend. The present invention will be described in detail below.
• the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 1 will also be referred to as the "ultraviolet-curable pressure-sensitive adhesive composition of Invention 1," and the ultraviolet-curable pressure-sensitive adhesive composition of Disclosure 12 will also be referred to as the “ultraviolet-curable pressure-sensitive adhesive composition of Invention 2.” Furthermore, matters common to the ultraviolet-curable pressure-sensitive adhesive composition of Invention 1 and the ultraviolet-curable pressure-sensitive adhesive composition of Invention 2 will be described as the "ultraviolet-curable pressure-sensitive adhesive composition of the present invention.” The present inventors have investigated the preparation of an ultraviolet-curable adhesive composition containing a radical polymerizable monomer containing a compound having a cyclic structure containing a nitrogen atom, a photopolymerization initiator, and a thickener, and adjusting the viscosity at 25° C.
• an ultraviolet-curable adhesive composition having excellent ultraviolet curability in the presence of oxygen, waterproofness and dustproofness, and shape stability after printing can be obtained, and have completed Invention 1.
• an ultraviolet-curable adhesive composition of Invention 1 a square-shaped cured product that maintains its shape without gaps can be formed without generating waste by printing into a predetermined shape and irradiating with ultraviolet light in the atmosphere.
• the present inventors have also investigated how to make the reaction rate of a cured product obtained by UV curing an ultraviolet-curable pressure-sensitive adhesive composition containing a monofunctional radical polymerizable monomer containing a compound having a cyclic structure containing a nitrogen atom, a photopolymerization initiator, and a crosslinking agent under specific conditions to a specific value or more, a specific range of gel fraction, and a specific temperature or less.
• a specific value or more, a specific range of gel fraction, and a specific temperature or less a specific temperature or less.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 has a viscosity measured using an E-type viscometer at 25° C. and 10 rpm, with a lower limit of 3 Pa ⁇ s and an upper limit of 100 Pa ⁇ s. When the viscosity is within this range, the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 has excellent printability and shape stability after printing.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 has a preferred lower limit of 5 Pa ⁇ s, a more preferred lower limit of 10 Pa ⁇ s, a preferred upper limit of 70 Pa ⁇ s, and a more preferred upper limit of 40 Pa ⁇ s.
• the viscosity of the ultraviolet-curable pressure-sensitive adhesive composition of the first invention can be measured, for example, using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer with an appropriate cone plate under conditions of 25° C. and 10 rpm.
• the ultraviolet-curable pressure-sensitive adhesive composition of the second invention has a viscosity at 25° C. of preferably 5 mPa ⁇ s at lower limit and 250,000 mPa ⁇ s at upper limit. With the viscosity in this range, the ultraviolet-curable pressure-sensitive adhesive composition of the second invention is suitable for printing.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 has a thixotropic index at 25° C. of preferably 1.05 at the lower limit and 2.5 at the upper limit. When the thixotropic index is in this range, the ultraviolet-curable pressure-sensitive adhesive composition has better printability and shape stability after printing.
• the more preferred lower limit of the thixotropic index is 1.1 and the more preferred upper limit is 2.0.
• the "thixotropic index” refers to the value obtained by dividing the viscosity measured using an E-type viscometer at 1 rpm by the viscosity measured at 10 rpm.
• the ultraviolet-curable adhesive composition of the present invention 1 contains a radically polymerizable monomer. By containing the radically polymerizable monomer, the ultraviolet-curable adhesive composition of the present invention 1 has excellent curability and adhesiveness after curing.
• the radical polymerizable monomer includes a compound having a cyclic structure containing a nitrogen atom.
• the ultraviolet-curable adhesive composition of the present invention 1 has excellent ultraviolet curing properties in the presence of oxygen.
• the compound having a cyclic structure containing a nitrogen atom preferably contains at least one selected from the group consisting of radical polymerizable monomers having a lactam structure and maleimide derivatives, and more preferably contains a maleimide derivative.
• the reaction system of the radical polymerizable monomer having the lactam structure and the maleimide derivative basically proceeds by a hydrogen abstraction (Type II) reaction. Photoradical polymerization by hydrogen abstraction reaction is not easily inhibited by oxygen, and can increase the surface curability. In addition, photoradical polymerization by hydrogen abstraction reaction does not produce a linear polymer like cleavage (Type I) reaction, but produces a branched polymer, and the cohesive strength is also high.
• the ultraviolet-curable pressure-sensitive adhesive composition contains at least one selected from the group consisting of the radical polymerizable monomer having the lactam structure and the maleimide derivative, and can obtain a cured product that is less likely to cause bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength.
• the above "maleimide derivative” means a compound having a maleimide group.
• the maleimide derivative preferably has a content of at least 50 mass% of maleimide derivatives not having a structure in which hydrogen is bonded to a heteroatom, or a content of maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom relative to 100 mass parts of the radical polymerizable monomer is 10 mass parts or less. This allows the cured product of the obtained ultraviolet-curable pressure-sensitive adhesive composition to have excellent impact resistance. More preferably, the content of maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom relative to 100 mass parts of the radical polymerizable monomer is 5 mass parts or less. It is particularly preferable that the maleimide derivative contains only maleimide derivatives that do not have a structure in which hydrogen is bonded to a heteroatom.
• Examples of structures in which hydrogen is bonded to the heteroatom include a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, etc.
• maleimide derivatives having a structure in which hydrogen is bonded to the heteroatom include N-(4-carboxycyclohexylmethyl)maleimide, 4-hydroxyphenylmaleimide, and N-(4-anilinophenyl)maleimide.
• the preferred lower limit of the content of the maleimide derivative in 100 parts by mass of the radical polymerizable monomer is 0.1 parts by mass, and the preferred upper limit is 20 parts by mass.
• the content of the maleimide derivative is within this range, the obtained ultraviolet-curable adhesive composition has better surface curability and adhesion.
• the more preferred lower limit of the content of the maleimide derivative is 0.5 parts by mass, and the more preferred upper limit is 10 parts by mass.
• the radical polymerizable monomer having a lactam structure is preferably a compound represented by the following formula (1):
• n represents an integer from 2 to 6.
• Examples of the compound represented by the above formula (1) include N-vinyl-2-pyrrolidone and N-vinyl- ⁇ -caprolactam. Of these, N-vinyl- ⁇ -caprolactam is preferred.
• the preferred lower limit of the content of the radical polymerizable monomer having the lactam structure in 100 parts by mass of the radical polymerizable monomer is 10 parts by mass, and the preferred upper limit is 60 parts by mass.
• the content of the radical polymerizable monomer having the lactam structure is within this range, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better surface curing properties and adhesion.
• the more preferred lower limit of the content of the radical polymerizable monomer having the lactam structure is 15 parts by mass, and the more preferred upper limit is 50 parts by mass.
• the radical polymerizable monomer preferably contains a monomer capable of serving as a hydrogen donor.
• a monomer capable of serving as a hydrogen donor By containing the radical polymerizable monomer in combination with at least one selected from the group consisting of the radical polymerizable monomer having a lactam structure and a maleimide derivative, it is possible to obtain a cured product that is less susceptible to bleeding due to a decrease in surface curability and cohesive failure due to a decrease in curability and cohesive strength.
• the above-mentioned "monomer capable of serving as a hydrogen donor” means a monomer having hydrogen capable of being used in a hydrogen abstraction reaction.
• the monomer capable of serving as the hydrogen donor is preferably a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the monomer capable of serving as the hydrogen donor be a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond
• hydrogen can be more easily provided to the hydrogen abstraction reaction.
• the monomer capable of serving as the hydrogen donor be a monomer having at least one structure selected from the group consisting of an ether bond, a phenoxy group, and an amide bond.
• the preferred lower limit of the content of the monomer capable of being a hydrogen donor in the radical polymerizable monomer is 20% by mass.
• the content of the monomer capable of being a hydrogen donor in the radical polymerizable monomer is 20% by mass or more, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better surface curability.
• the more preferred lower limit of the content of the monomer capable of being a hydrogen donor in the radical polymerizable monomer is 35% by mass.
• the upper limit of the content of the monomer capable of serving as a hydrogen donor in the radical polymerizable monomer is preferably 90% by mass, and more preferably 70% by mass.
• the radical polymerizable monomer preferably contains 50% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the radical polymerizable monomer contains 50% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond
• the obtained ultraviolet-curable pressure-sensitive adhesive composition has better curability and impact resistance of the cured product.
• the radical polymerizable monomer contains 70% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the radical polymerizable monomer preferably contains a monofunctional (meth)acrylic monomer.
• the radical polymerizable monomer contains the monofunctional (meth)acrylic monomer, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better adhesion.
• (meth)acrylic means acrylic or methacrylic
• the term "(meth)acrylic monomer” means a monomer having a (meth)acryloyl group
• the term “(meth)acryloyl” means acryloyl or methacryloyl.
• the term "monofunctional (meth)acrylic monomer” means a monomer having one (meth)acryloyl group in one molecule.
• Examples of the monofunctional (meth)acrylic monomer include monofunctional (meth)acrylic acid ester compounds, monofunctional (meth)acrylamide compounds, etc.
• Examples of the monofunctional (meth)acrylic acid ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 2-hydroxybutyl (meth
• Examples of the monofunctional (meth)acrylamide compounds include N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-hydroxyethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide.
• the preferred lower limit of the content of the monofunctional (meth)acrylic monomer in 100 parts by mass of the radical polymerizable monomer is 10 parts by mass, and the preferred upper limit is 99 parts by mass.
• the content of the monofunctional (meth)acrylic monomer is within this range, the obtained ultraviolet-curable adhesive composition has better printability and adhesion to various substrates.
• the more preferred lower limit of the content of the monofunctional (meth)acrylic monomer is 20 parts by mass, and the more preferred upper limit is 95 parts by mass.
• the radical polymerizable monomer preferably contains a polyfunctional (meth)acrylic monomer.
• the ultraviolet-curable pressure-sensitive adhesive composition of the first invention has better adhesion and retention performance after curing.
• polyfunctional (meth)acrylic monomer means a monomer having two or more (meth)acryloyl groups in one molecule.
• polyfunctional (meth)acrylic monomer examples include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, and polyfunctional epoxy (meth)acrylates.
• (meth)acrylate means acrylate or methacrylate
• epoxy (meth)acrylate refers to a compound in which all epoxy groups in an epoxy compound have been reacted with (meth)acrylic acid.
• the above-mentioned polyfunctional urethane (meth)acrylate can be obtained, for example, by reacting a (meth)acrylic acid derivative having a hydroxyl group with an isocyanate compound in the presence of a catalytic amount of a tin-based compound.
• MDI diphenylmethane-4,4'-
• isocyanate compound serving as a raw material for the polyfunctional urethane (meth)acrylate a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used.
• the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.
• Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylates, mono(meth)acrylates of dihydric alcohols, and mono(meth)acrylates or di(meth)acrylates of trihydric alcohols.
• Examples of the hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate.
• Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol.
• Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin.
• polyfunctional (meth)acrylic acid ester compounds examples include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glyco
• polyfunctional epoxy (meth)acrylate examples include bisphenol A type epoxy (meth)acrylate, bisphenol F type epoxy (meth)acrylate, bisphenol E type epoxy (meth)acrylate, and caprolactone modified versions of these.
• the preferred lower limit of the content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the radical polymerizable monomer is 0.5 parts by mass, and the preferred upper limit is 20 parts by mass.
• the content of the polyfunctional (meth)acrylic monomer is within this range, the resulting ultraviolet-curable adhesive composition has better adhesion and retention performance after curing.
• a more preferred lower limit of the content of the polyfunctional (meth)acrylic monomer is 1 part by mass, and a more preferred upper limit is 10 parts by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 contains a monofunctional radically polymerizable monomer.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 has excellent adhesiveness after curing.
• the above-mentioned "monofunctional radically polymerizable monomer” means a monomer having one radically polymerizable group in one molecule.
• the monofunctional radically polymerizable monomer includes a compound having a cyclic structure containing a nitrogen atom.
• the ultraviolet-curable adhesive composition of the present invention 2 has excellent ultraviolet curing properties in the presence of oxygen.
• the compound having a cyclic structure containing a nitrogen atom preferably contains at least one selected from the group consisting of monofunctional radically polymerizable monomers having a lactam structure and maleimide derivatives, and more preferably contains a maleimide derivative.
• the reaction system of the monofunctional radical polymerizable monomer having a lactam structure and the maleimide derivative basically proceeds by a hydrogen abstraction (Type II) reaction. Photoradical polymerization by hydrogen abstraction reaction is not easily inhibited by oxygen, and can increase the surface curability. In addition, photoradical polymerization by hydrogen abstraction reaction does not produce a linear polymer like cleavage (Type I) reaction, but produces a branched polymer, and the cohesive strength is also high.
• the ultraviolet-curable pressure-sensitive adhesive composition contains at least one selected from the group consisting of the monofunctional radical polymerizable monomer having a lactam structure and the maleimide derivative, and can obtain a cured product that is less likely to cause bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength.
• the maleimide derivative preferably has a content of at least 50 mass% of maleimide derivatives not having a structure in which hydrogen is bonded to a heteroatom, or a content of maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom relative to 100 mass parts of the monofunctional radical polymerizable monomer is 10 mass parts or less.
• the content of maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom relative to 100 mass parts of the monofunctional radical polymerizable monomer is 5 mass parts or less. It is particularly preferable that the maleimide derivative contains only maleimide derivatives that do not have a structure in which hydrogen is bonded to a heteroatom.
• Examples of structures in which hydrogen is bonded to the heteroatom include a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, etc.
• maleimide derivatives having a structure in which hydrogen is bonded to the heteroatom include N-(4-carboxycyclohexylmethyl)maleimide, 4-hydroxyphenylmaleimide, and N-(4-anilinophenyl)maleimide.
• the preferred lower limit of the content of the maleimide derivative in 100 parts by mass of the monofunctional radical polymerizable monomer is 0.1 parts by mass, and the preferred upper limit is 20 parts by mass.
• the content of the maleimide derivative is within this range, the obtained ultraviolet-curable adhesive composition has better surface curing properties and adhesion.
• the more preferred lower limit of the content of the maleimide derivative is 0.5 parts by mass, and the more preferred upper limit is 10 parts by mass.
• the monofunctional radically polymerizable monomer having a lactam structure is preferably a compound represented by the following formula (1):
• n represents an integer from 2 to 6.
• Examples of the compound represented by the above formula (1) include N-vinyl-2-pyrrolidone and N-vinyl- ⁇ -caprolactam. Of these, N-vinyl- ⁇ -caprolactam is preferred.
• the preferred lower limit of the content of the monofunctional radical polymerizable monomer having a lactam structure in 100 parts by mass of the monofunctional radical polymerizable monomer is 10 parts by mass, and the preferred upper limit is 60 parts by mass.
• the content of the monofunctional radical polymerizable monomer having a lactam structure is within this range, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better surface curing properties and adhesion.
• the more preferred lower limit of the content of the monofunctional radical polymerizable monomer having a lactam structure is 15 parts by mass, and the more preferred upper limit is 50 parts by mass.
• the monofunctional radical polymerizable monomer preferably contains a monomer capable of acting as a hydrogen donor.
• the monofunctional radical polymerizable monomer in combination with at least one selected from the group consisting of the monofunctional radical polymerizable monomer having a lactam structure and maleimide derivatives, it becomes possible to obtain a cured product that is less susceptible to bleeding due to a decrease in surface curability and cohesive failure due to a decrease in curability and cohesive strength.
• the monomer capable of serving as the hydrogen donor is preferably a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the monomer capable of serving as the hydrogen donor be a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond
• hydrogen can be more easily provided to the hydrogen abstraction reaction.
• the monomer capable of serving as the hydrogen donor be a monomer having at least one structure selected from the group consisting of an ether bond, a phenoxy group, and an amide bond.
• the preferred lower limit of the content of the monomer capable of being the hydrogen donor in the monofunctional radical polymerizable monomer is 20% by mass.
• the content of the monomer capable of being the hydrogen donor in the monofunctional radical polymerizable monomer is 20% by mass or more, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better surface curability.
• the more preferred lower limit of the content of the monomer capable of being the hydrogen donor in the monofunctional radical polymerizable monomer is 35% by mass.
• the upper limit of the content of the monomer capable of serving as a hydrogen donor in the monofunctional radically polymerizable monomer is preferably 90% by mass, and more preferably 70% by mass.
• the monofunctional radical polymerizable monomer preferably contains 30% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the monofunctional radical polymerizable monomer contains 30% by mass or more of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond
• the obtained ultraviolet-curable pressure-sensitive adhesive composition has better curability and adhesiveness and retention performance of the cured product.
• the monofunctional radical polymerizable monomer more preferably contains 50% by mass or more, and even more preferably contains 70% by mass or more, of a monomer having at least one structure selected from the group consisting of an ether bond, an acetyl group, a phenoxy group, a benzyl group, and an amide bond.
• the monofunctional radical polymerizable monomer preferably contains a monofunctional (meth)acrylic monomer.
• the resulting ultraviolet-curable pressure-sensitive adhesive composition has superior adhesion.
• Examples of the monofunctional (meth)acrylic monomer include monofunctional (meth)acrylic acid ester compounds, monofunctional (meth)acrylamide compounds, etc.
• Examples of the monofunctional (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxybutyl (meth)
• Examples of the monofunctional (meth)acrylamide compounds include N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-hydroxyethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator.
• the photopolymerization initiator preferably includes at least one selected from the group consisting of hydrogen abstraction type photopolymerization initiators and polymer type photopolymerization initiators.
• at least one selected from the group consisting of hydrogen abstraction type photopolymerization initiators and polymer type photopolymerization initiators as the photopolymerization initiator, it becomes possible to obtain a cured product in which bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength are less likely to occur in the obtained ultraviolet-curable pressure-sensitive adhesive composition.
• a benzophenone-based photopolymerization initiator is preferable.
• the benzophenone-based photopolymerization initiator include benzophenone, 4-chlorobenzophenone, 4,4'-dimethylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, o-benzoyl methyl benzoate, 3,3'-dimethyl-4-methoxybenzophenone, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 4-morpholinobenzophenone, 4,4'-diphenoxybenzophenone, 4-hydroxybenzophenone, 2-carboxybenzophenone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methyl-propionyl)-benzyl)-phenyl)-2-methyl-propan-1-one, 1-(4-(4-benzoylphenylthio)phenyl)-2-to
• hydrogen abstraction type photopolymerization initiators include Esacure TZT and Omnirad 4MBZ (both manufactured by IGM Resins).
• polymeric photopolymerization initiator examples include polymers of ethyl (2,4,6-trimethylbenzoyl)-phenyl phosphonate, polyethylene glycol di( ⁇ -4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate, and bis(benzophenone-2-carboxylic acid) polyethylene glycol ester.
• Omnipol TP Omnipol 910
• Omnipol 2702 All manufactured by IGM Resins.
• cleavage type photopolymerization initiator As the photopolymerization initiator, a cleavage type photopolymerization initiator can also be used.
• the cleavage type photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.
• the content of the photopolymerization initiator is preferably 0.5 parts by mass at the lower limit and 15 parts by mass at the upper limit with respect to 100 parts by mass of the radical polymerizable monomer.
• the content of the photopolymerization initiator being within this range, the obtained ultraviolet-curable pressure-sensitive adhesive composition is more excellent in storage stability, curability, and adhesiveness after curing.
• the more preferred lower limit of the content of the photopolymerization initiator is 3 parts by mass, and the more preferred upper limit is 9 parts by mass.
• the content of the photopolymerization initiator is preferably 0.5 parts by mass at the lower limit and 15 parts by mass at the upper limit relative to 100 parts by mass of the monofunctional radical polymerizable monomer.
• the obtained ultraviolet-curable pressure-sensitive adhesive composition is more excellent in storage stability, curability, and adhesiveness after curing.
• the more preferred lower limit of the content of the photopolymerization initiator is 1 part by mass, and the more preferred upper limit is 9 parts by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention preferably contains an amine compound.
• an amine compound As described above, by using the amine compound in combination with the hydrogen abstraction type photopolymerization initiator, it becomes possible to obtain an ultraviolet-curable pressure-sensitive adhesive composition that is less susceptible to bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength, and thus a cured product that is less susceptible to bleeding due to a decrease in surface curability and cohesive strength.
• the amine compound preferably contains 50% by mass or more of amine compounds that do not have a structure in which hydrogen is bonded to a heteroatom.
• the obtained ultraviolet-curable adhesive composition can produce a cured product that is less susceptible to bleeding due to a decrease in surface curability and cohesive failure due to a decrease in surface curability and cohesive strength.
• the amine compound more preferably contains 75% by mass or more of amine compounds that do not have a structure in which hydrogen is bonded to a heteroatom, and most preferably contains 100% by mass.
• Examples of amine compounds that do not have a structure in which hydrogen is bonded to the heteroatom include (bis-N,N-(4-dimethylaminobenzoyl)oxyethylene-1-yl)-methylamine, bis(2-morpholinoethyl)ether, 1-methyl 10-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.
• amine compounds that do not have a structure in which hydrogen is bonded to the heteroatom
• commercially available examples include Esacure A198 (manufactured by IGM Resins), U-cat 660 (manufactured by San-Apro), Eversorb 93 (manufactured by Everlight Chemical), Adeka STAB LA-52, and Adeka STAB LA-72 (all manufactured by ADEKA).
• the preferred lower limit of the content of the amine compound in the total of 100 parts by mass of the ultraviolet-curable adhesive composition excluding the photopolymerization initiator is 0.1 parts by mass, and the preferred upper limit is 10 parts by mass.
• the content of the amine compound is 0.1 parts by mass or more, the obtained ultraviolet-curable adhesive composition has better surface curing properties.
• the content of the amine compound is 10 parts by mass or less, the obtained adhesive sheet is less likely to cause cohesive failure.
• the more preferred lower limit of the content of the amine compound is 0.5 parts by mass, and the more preferred upper limit is 8.0 parts by mass.
• the preferred lower limit of the content of the amine compound in the total of 100 parts by mass of the ultraviolet-curable adhesive composition excluding the photopolymerization initiator is 0.5 parts by mass, and the preferred upper limit is 8.0 parts by mass.
• the content of the amine compound is 0.5 parts by mass or more, the obtained ultraviolet-curable adhesive composition has better surface curing properties.
• the content of the amine compound is 8.0 parts by mass or less, the obtained adhesive sheet is less likely to cause cohesive failure.
• the more preferred lower limit of the content of the amine compound is 1.0 parts by mass, and the more preferred upper limit is 5.0 parts by mass.
• the ultraviolet-curable adhesive composition of the first invention contains a thickener. By containing the thickener, it becomes easy to adjust the viscosity and thixotropic index of the ultraviolet-curable adhesive composition of the first invention to the above-mentioned ranges.
• the ultraviolet-curable adhesive composition of the second invention may further contain a thickener.
• thermoplastic resin is preferably a compound that does not contain a reactive double bond, or a compound that has a reactive double bond but does not substantially exhibit photoradical polymerization reactivity.
• thermoplastic resin examples include (meth)acrylic copolymers, polyolefins, polyesters, polyamides, polyurethanes, and the like.
• thermoplastic resin contains a (meth)acrylic copolymer.
• the (meth)acrylic copolymer may, for example, be a solvent-free acrylic polymer.
• the solvent-free acrylic polymer include a polymer of at least one monomer selected from (meth)acrylic acid alkyl esters having an alkyl group with 1 to 20 carbon atoms, and a copolymer of the monomer and another copolymerizable monomer.
• commercially available ones include, for example, the ARUFON-UP1000 series, UH2000 series, UC3000 series (all manufactured by Toagosei Co., Ltd.), the Clarity LA series, and the Clarity LK series (all manufactured by Kuraray Co., Ltd.).
• the preferred lower limit of the weight average molecular weight of the thermoplastic resin is 5,000, and the preferred upper limit is 800,000. When the weight average molecular weight of the thermoplastic resin is within this range, it becomes easier to adjust the viscosity and thixotropic index of the obtained ultraviolet-curable pressure-sensitive adhesive composition to the above-mentioned range.
• the more preferred lower limit of the weight average molecular weight of the thermoplastic resin is 10,000, and the more preferred upper limit is 500,000.
• the weight average molecular weight is a value obtained by measuring by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converting the weight average molecular weight into polystyrene equivalent. Examples of columns used for measuring the weight average molecular weight converted into polystyrene equivalent by GPC include Shodex LF-804 (manufactured by Showa Denko KK).
• the content of the thermoplastic resin is preferably 5 parts by mass at the lower limit and 85 parts by mass at the upper limit with respect to 100 parts by mass of the radical polymerizable monomer.
• the content of the thermoplastic resin being within this range, it becomes easier to adjust the viscosity and thixotropic index of the obtained ultraviolet-curable adhesive composition to the above-mentioned range, and the decrease in adhesion at high temperatures can also be suppressed.
• the more preferred lower limit of the content of the thermoplastic resin is 15 parts by mass, and the more preferred upper limit is 65 parts by mass.
• the content of the thermoplastic resin is preferably 1.0 parts by mass and 70 parts by mass relative to 100 parts by mass of the monofunctional radical polymerizable monomer.
• the content of the thermoplastic resin being within this range, the viscosity of the obtained ultraviolet-curable adhesive composition is improved, a thick coating film can be formed, the printability is superior, and the decrease in adhesion at high temperatures can be suppressed.
• the more preferable lower limit of the content of the thermoplastic resin is 5.0 parts by mass, and the more preferable upper limit is 60 parts by mass.
• polymeric thixotropy regulator examples include amide, castor oil, polyether phosphate ester, etc.
• the solid thickener may be inorganic particles or organic particles.
• the inorganic particles include insulating and heat-dissipating fillers, conductive fillers, and high dielectric constant fillers.
• the insulating and heat-dissipating filler include talc, silica, alumina, aluminum nitride, magnesium oxide, and diamond.
• the conductive filler include carbon filler, metal filler, metal oxide filler, and metal-coated filler.
• An example of the high dielectric constant filler is barium titanate.
• the organic particles include (meth)acrylic copolymer particles, melamine resin particles, (meth)acrylic-styrene copolymer particles, and organic-inorganic composite particles.
• the organic-inorganic composite particles include, for example, particles made of silicone-acrylic resin.
• the organic particles may be hollow particles or thermally expanded particles.
• the solid thickener has a preferred lower limit of 5 nm and a preferred upper limit of 20 ⁇ m. When the solid thickener has an average particle size in this range, the resulting ultraviolet-curable adhesive composition has better printability.
• the solid thickener has a more preferred lower limit of 10 nm and a more preferred upper limit of 10 ⁇ m.
• the average particle size of the solid thickener can be measured by dispersing the solid thickener in a solvent (water, organic solvent, etc.) using a particle size distribution measuring device such as NICOMP 380ZLS (manufactured by PARTICLE SIZING SYSTEMS).
• the content of the solid thickener is preferably 1.0 parts by mass and 70 parts by mass relative to 100 parts by mass of the radical polymerizable monomer.
• the content of the solid thickener in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is within this range, it becomes easier to adjust the viscosity and thixotropic index of the obtained ultraviolet-curable pressure-sensitive adhesive composition to the above-mentioned range.
• the more preferred lower limit of the content of the solid thickener in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is 2.0 parts by mass, and the more preferred upper limit is 50 parts by mass.
• the content of the solid thickener is preferably 1.0 parts by mass and 70 parts by mass relative to 100 parts by mass of the monofunctional radical polymerizable monomer.
• the content of the solid thickener in the ultraviolet-curable adhesive composition of the present invention 2 is within this range, the obtained ultraviolet-curable adhesive composition has better printability.
• the more preferred lower limit of the content of the solid thickener in the ultraviolet-curable adhesive composition of the present invention 2 is 2.0 parts by mass and the more preferred upper limit is 50 parts by mass.
• the ultraviolet-curable adhesive composition of the present invention 2 contains a crosslinking agent having two or more reactive functional groups in one molecule.
• the ultraviolet-curable adhesive composition of the present invention 1 preferably contains a crosslinking agent having two or more reactive functional groups in one molecule.
• the crosslinking agent preferably has, as the reactive functional group, at least one type selected from the group consisting of an isocyanate group, an epoxy group, an aldehyde group, a hydroxyl group, an amino group, a (meth)acryloyl group, and a vinyl group, in one molecule, in a number of two or more, and more preferably has at least one type selected from the group consisting of an isocyanate group, an epoxy group, and a (meth)acryloyl group, in one molecule, in a number of two or more.
• the crosslinking agent preferably has, as the reactive functional group, at least one type selected from the group consisting of an isocyanate group, an epoxy group, an aldehyde group, a hydroxyl group, and an amino group, in one molecule, in a quantity of two or more, and more preferably has at least one type selected from the group consisting of an isocyanate group and an epoxy group, in one molecule.
• Examples of the crosslinking agent having two or more (meth)acryloyl groups in one molecule in the ultraviolet-curable adhesive composition of the present invention 2 include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, polyfunctional epoxy (meth)acrylates, etc.
• the above-mentioned polyfunctional urethane (meth)acrylate can be obtained, for example, by reacting a (meth)acrylic acid derivative having a hydroxyl group with an isocyanate compound in the presence of a catalytic amount of a tin-based compound.
• MDI diphenylmethane-4,4'-
• isocyanate compound serving as a raw material for the polyfunctional urethane (meth)acrylate a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used.
• the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.
• Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylates, mono(meth)acrylates of dihydric alcohols, and mono(meth)acrylates or di(meth)acrylates of trihydric alcohols.
• Examples of the hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate.
• Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol.
• Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin.
• polyfunctional (meth)acrylic acid ester compounds examples include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added
• polyfunctional epoxy (meth)acrylate examples include bisphenol A type epoxy (meth)acrylate, bisphenol F type epoxy (meth)acrylate, bisphenol E type epoxy (meth)acrylate, and caprolactone modified versions of these.
• crosslinking agents having the above-mentioned isocyanate groups include polyisocyanates, polymeric MDI, blocked isocyanates, etc.
• crosslinking agents having the above-mentioned epoxy groups examples include N,N,N',N'-tetraglycidyl-m-xylylenediamine, etc.
• the preferred lower limit of the content of the crosslinking agent relative to 100 parts by mass of the monofunctional radical polymerizable monomer is 0.5 parts by mass.
• the content of the crosslinking agent in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 is 0.5 parts by mass or more, the obtained ultraviolet-curable pressure-sensitive adhesive composition has better retention performance after curing.
• the more preferred lower limit of the content of the crosslinking agent is 1.0 parts by mass.
• the upper limit of the content of the crosslinking agent in the ultraviolet-curable pressure-sensitive adhesive composition of invention 2 is preferably 10 parts by mass, and more preferably 5.0 parts by mass.
• the preferred lower limit of the content of the crosslinking agent relative to 100 parts by mass of the radical polymerizable monomer is 0.5 parts by mass.
• the content of the crosslinking agent in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is 0.5 parts by mass or more, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better adhesion and retention performance after curing.
• the more preferred lower limit of the content of the crosslinking agent in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is 1.0 parts by mass.
• the upper limit of the content of the crosslinking agent in the ultraviolet-curable pressure-sensitive adhesive composition of invention 1 is preferably 10 parts by mass, and more preferably 5.0 parts by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention may further contain a tackifier.
• a tackifier include rosin-based resins and terpene-based resins.
• the rosin-based resin may, for example, be rosin diol.
• the rosin diol is not particularly limited as long as it is a rosin-modified diol having two rosin skeletons and two hydroxyl groups in the molecule.
• Diols having a rosin component in the molecule are called rosin polyols, and these include polyether types such as polypropylene glycol (PPG) in which the skeleton excluding the rosin component is polyether, and polyester types such as condensation polyester polyols, lactone polyester polyols, and polycarbonate diols.
• PPG polypropylene glycol
• polyester types such as condensation polyester polyols, lactone polyester polyols, and polycarbonate diols.
• rosin diol examples include rosin ester obtained by reacting rosin with a polyhydric alcohol, epoxy-modified rosin ester obtained by reacting rosin with an epoxy compound, and modified rosin having a hydroxyl group, such as polyether having a rosin skeleton, etc. These can be produced by conventionally known methods.
• the rosin component includes, for example, abietic acid and its derivatives, such as pimaric acid type resin acids as dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, neoabietic acid, and levopimaric acid, hydrogenated rosins obtained by hydrogenating these, and disproportionated rosins obtained by disproportionating these.
• abietic acid and its derivatives such as pimaric acid type resin acids as dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, neoabietic acid, and levopimaric acid, hydrogenated rosins obtained by hydrogenating these, and disproportionated rosins obtained by disproportionating these.
• rosin-based resins include Pine Crystal D-6011, Pine Crystal KE-615-3, Pine Crystal KR-614, Pine Crystal KE-100, Pine Crystal KE-311, Pine Crystal KE-359, Pine Crystal KE-604, and Pine Crystal D-6250 (all manufactured by Arakawa Chemical Industries Co., Ltd.).
• the terpene resin examples include terpene phenol resins.
• the terpene phenol resin is a copolymer of phenol and a terpene resin, which is an essential oil component obtained from natural products such as rosin and orange peel, and also includes partially hydrogenated terpene phenol resins in which at least a portion of the copolymer is hydrogenated, and fully hydrogenated terpene phenol resins in which the copolymer is completely hydrogenated.
• the fully hydrogenated terpene phenolic resin is a terpene resin obtained by substantially completely hydrogenating a terpene phenolic resin
• the partially hydrogenated terpene phenolic resin is a terpene resin obtained by partially hydrogenating a terpene phenolic resin.
• the terpene phenolic resin has a double bond derived from a terpene and an aromatic ring double bond derived from a phenol. Therefore, the fully hydrogenated terpene phenolic resin means a resin in which both the terpene portion and the phenol portion are completely or almost hydrogenated, and the partially hydrogenated terpene phenolic resin means a resin in which the degree of hydrogenation of these portions is not complete but partial.
• the hydrogenation method and reaction form are not particularly limited.
• examples of commercially available ones include YS Polystar NH (fully hydrogenated terpene phenol-based resin) manufactured by Yasuhara Chemical Co., Ltd.
• the content of the tackifier is preferably 5 parts by mass at the lower limit and 50 parts by mass at the upper limit, relative to 100 parts by mass of the total UV-curable adhesive composition not including the tackifier. When the content of the tackifier is within this range, the resulting UV-curable adhesive composition has better adhesion to various substrates.
• a more preferred lower limit of the content of the tackifier is 10 parts by mass, and a more preferred upper limit is 35 parts by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention may contain a defoaming agent.
• the defoaming agent include silicone-based defoaming agents, acrylic polymer-based defoaming agents, vinyl ether polymer-based defoaming agents, and olefin polymer-based defoaming agents.
• the preferred lower limit of the content of the defoaming agent relative to 100 parts by mass of the radical polymerizable monomer is 0.1 parts by mass, and the preferred upper limit is 5 parts by mass.
• the content of the defoaming agent in the ultraviolet-curable adhesive composition of the first invention is within this range, the resulting ultraviolet-curable adhesive composition has better printability.
• the more preferred lower limit of the content of the defoaming agent in the ultraviolet-curable adhesive composition of the first invention is 0.5 parts by mass, and the more preferred upper limit is 3 parts by mass.
• the preferred lower limit of the content of the defoaming agent relative to 100 parts by mass of the monofunctional radical polymerizable monomer is 0.1 parts by mass, and the preferred upper limit is 5 parts by mass.
• the content of the defoaming agent in the ultraviolet-curable pressure-sensitive adhesive composition of the second invention is within this range, the resulting ultraviolet-curable pressure-sensitive adhesive composition has better printability.
• the more preferred lower limit of the content of the defoaming agent in the ultraviolet-curable pressure-sensitive adhesive composition of the second invention is 0.5 parts by mass, and the more preferred upper limit is 3 parts by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention may contain a plasticizer.
• the plasticizer include organic acid esters, organic phosphates, and organic phosphites.
• Examples of the organic acid ester include monobasic organic acid esters and polybasic organic acid esters.
• Examples of the monobasic organic acid ester include glycol esters obtained by reacting a monobasic organic acid such as butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octylic acid, 2-ethylhexyl acid, pelargonic acid (n-nonylic acid), or decylic acid with a glycol such as triethylene glycol, tetraethylene glycol, or tripropylene glycol.
• a monobasic organic acid such as butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octylic acid, 2-ethylhexyl acid, pelargonic acid (n-nonylic acid), or decylic acid with a glycol such as triethylene glycol
• polybasic organic acid ester examples include ester compounds obtained by reacting a polybasic organic acid such as adipic acid, sebacic acid, or azelaic acid with an alcohol having a linear or branched structure having 4 to 8 carbon atoms.
• organic acid esters include triethylene glycol di-2-ethylbutyrate (3GH), triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycol dicaprylate, triethylene glycol di-n-octanoate, and triethylene glycol di-n-heptanoate (3G7).
• tetraethylene glycol di-n-heptanoate (4G7) tetraethylene glycol di-2-ethylhexanoate, dibutyl sebacate, dioctyl azelate, dibutyl carbitol adipate, ethylene glycol di-2-ethylbutyrate, and 1,3-propylene glycol di-2-ethylbutyrate.
• 1,4-butylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate, and dipropylene glycol di-2-ethylbutyrate are also included.
• Examples include triethylene glycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate (4GH), diethylene glycol dicapryate, dihexyl adipate (DHA), dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, etc.
• Other examples include oil-modified sebacic acid alkyd, a mixture of a phosphate ester and an adipate ester, and a mixed adipate ester made from an alkyl alcohol having 4 to 9 carbon atoms and a cyclic alcohol having 4 to 9 carbon atoms.
• the organic phosphate or organic phosphite may be a compound obtained by a condensation reaction between phosphoric acid or phosphorous acid and an alcohol.
• a compound obtained by a condensation reaction between an alcohol having 1 to 12 carbon atoms and phosphoric acid or phosphorous acid is preferable.
• the alcohol having 1 to 12 carbon atoms include methanol, ethanol, butanol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, and benzyl alcohol.
• organic phosphate ester or organic phosphite ester examples include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tri(butoxyethyl) phosphate, tri(2-ethylhexyl) phosphite, isodecylphenyl phosphate, and triisopropyl phosphate.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention may further contain various known additives, such as a silane coupling agent, a sensitizer, a heat curing agent, a cure retarder, an antioxidant, a storage stabilizer, a dispersant, an ultraviolet absorber, a radical polymerization inhibitor, a light stabilizer, a heat stabilizer, a dehydrating agent, a colorant, an antibacterial/antifungal agent, a flame retardant, a leveling agent, a wetting/dispersing agent, an anti-settling agent, an anti-sagging agent, an emulsifier, an anti-fogging agent, a lubricant, an antifouling agent, an antistatic agent, and a conductive agent, within a range that does not impair the object of the present invention.
• additives such as a silane coupling agent, a sensitizer, a heat curing agent, a cure retarder, an antioxidant, a storage stabilizer, a dispersant, an
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention is substantially free of organic solvents. Specifically, it is preferable that the content of the organic solvent is 1.5 mass% or less relative to 100 mass% of the ultraviolet-curable pressure-sensitive adhesive composition.
• Examples of the method for preparing the ultraviolet-curable pressure-sensitive adhesive composition of the first invention include a method in which the radical polymerizable monomer, the photopolymerization initiator, the thickener, the amine compound, and additives added as necessary are mixed using a mixer.
• Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.
• Examples of the method for preparing the ultraviolet-curable pressure-sensitive adhesive composition of the second invention include a method in which the monofunctional radical polymerizable monomer, the photopolymerization initiator, the crosslinking agent, the amine compound, and additives added as necessary are mixed using a mixer.
• Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 is obtained by applying the ultraviolet-curable pressure-sensitive adhesive composition to a substrate, and irradiating the coated surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 at an irradiation dose of 3000 mJ/cm 2 under an atmospheric environment, and the lower limit of the reaction rate of the cured product having a thickness of 50 ⁇ m is 90%.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is obtained by applying the ultraviolet-curable pressure-sensitive adhesive composition to a substrate, and irradiating the coated surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 at an irradiation dose of 3000 mJ/cm 2 under an atmospheric environment, and the lower limit of the reaction rate of the cured product having a thickness of 50 ⁇ m is 90%.
• a PET film with a release treatment on the surface release PET film
• the above conditions are that after the ultraviolet-curable pressure-sensitive adhesive composition is coated on the substrate, ultraviolet light is irradiated in the presence of oxygen without covering the coated surface with a separator.
• the reaction rate of the cured product reflects the ultraviolet light reactivity in the presence of oxygen. Since the reaction rate of the cured product is 90% or more, it can be said that the UV reactivity in the presence of oxygen is sufficiently high, making it possible to apply a method in which the UV-curable pressure-sensitive adhesive composition is printed in a desired shape and then bonded to an adherend.
• the lower limit of the reaction rate of the cured product in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 is preferably 92%, more preferably 94%.
• the lower limit of the reaction rate of the cured product in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is more preferably 91%, still more preferably 93%.
• the higher the reaction rate of the cured product the more preferable it is, but the practical upper limit is 99%.
• the reaction rate of the cured product can be measured, for example, according to the following procedure. That is, the ultraviolet-curable pressure-sensitive adhesive composition is first coated on a release PET film as a substrate, and then, without sealing the coated surface, the ultraviolet-curable pressure-sensitive adhesive composition is cured by simultaneously irradiating the coated surface with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 at an irradiation dose of 3000 mJ/ cm2 using an ultraviolet irradiation device under an atmospheric environment to obtain a cured product having a thickness of 50 ⁇ m.
• reaction rate (%) (total mass of aluminum pan and sample after drying ⁇ mass of aluminum pan before drying)/(mass of sample before swelling) ⁇ 100
• the upper limit of the temperature at which the loss tangent is maximized in a temperature range of 50° C. or less (hereinafter also referred to as the "glass transition temperature of the cured product") in a viscoelasticity chart obtained by performing dynamic viscoelasticity measurement on the cured product under the conditions of a shear method, a measurement temperature of -70° C. to 200° C., and a frequency of 1 Hz is 20° C. Since the glass transition temperature of the cured product is 20° C. or less, the ultraviolet-curable pressure-sensitive adhesive composition of the second invention has excellent adhesion and retention performance after curing.
• the upper limit of the glass transition temperature of the cured product in the ultraviolet-curable pressure-sensitive adhesive composition of the second invention is preferably 15° C., more preferably 10° C.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is coated on a substrate, and the coated surface is not sealed, and in an atmospheric environment, ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 is irradiated at an irradiation dose of 3000 mJ/cm 2 to obtain a cured product having a thickness of 50 ⁇ m.
• the glass transition temperature of the cured product is preferably ⁇ 40° C. at the lower limit and 20° C. at the upper limit.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 has better adhesion and retention performance after curing.
• the glass transition temperature of the cured product in the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 1 is more preferably ⁇ 20° C. at the lower limit and 15° C. at the upper limit.
• the glass transition temperature of the cured product can be measured, for example, according to the following procedure. That is, first, a cured product obtained in the same manner as in the reaction rate measurement is subjected to dynamic viscoelasticity measurement under the following conditions using a dynamic viscoelasticity measuring device to obtain a viscoelasticity chart. In the obtained viscoelasticity chart, the tan ⁇ peak temperature in a temperature range of 50° C. or less can be determined as the glass transition temperature.
• the dynamic viscoelasticity measuring device for example, DVA-200 (manufactured by IT Measurement & Control Co., Ltd.) can be used.
• the lower limit of the gel fraction of the cured product is 20% by mass, and the upper limit is 80% by mass.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention 2 has excellent adhesion and retention performance after curing.
• the lower limit of the gel fraction of the cured product is preferably 30% by mass, more preferably 40% by mass, and the upper limit is preferably 75% by mass, more preferably 70% by mass.
• the ultraviolet-curable adhesive composition of the present invention 1 is coated on a substrate, and the coated surface is not sealed, and the cured product having a thickness of 50 ⁇ m is irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 in an atmospheric environment at an irradiation dose of 3000 mJ/cm 2.
• the gel fraction of the cured product is preferably 20% by mass at the lower limit and 80% by mass at the upper limit. When the gel fraction of the cured product is within the above range, the ultraviolet-curable adhesive composition of the present invention 1 has better adhesion and retention performance after curing.
• the more preferred lower limit of the gel fraction of the cured product in the ultraviolet-curable adhesive composition of the present invention 1 is 30% by mass, and the more preferred upper limit is 70% by mass.
• the ultraviolet-curable adhesive composition of the first aspect of the present invention is used for printing.
• the ultraviolet-curable adhesive composition of the second aspect of the present invention is preferably used for printing. If an adhesive layer is formed by applying a desired pattern onto an adherend (substrate) by printing, there is an advantage that the cutting process can be omitted compared to the case where an adhesive of a desired shape is obtained by cutting a sheet-like adhesive just before lamination. As a result, it is possible to suppress the generation of waste and reduce the environmental load. In addition, since lamination without gaps is possible by printing, the composition has excellent waterproof and dustproof properties.
• Examples of the method for printing the ultraviolet-curable pressure-sensitive adhesive composition of the first invention include screen printing, stencil printing, reverse offset printing, etc. Among these, screen printing is preferably used.
• Examples of the method for applying the ultraviolet-curable pressure-sensitive adhesive composition of the second invention include gravure printing, flexographic printing, slot die coating, knife coating, inkjet printing, spray coating, spin coating, screen printing, stencil printing, reverse offset printing, etc. Among these, screen printing, stencil printing, and reverse offset printing are preferably used, and screen printing is more preferably used.
• the ultraviolet-curable adhesive composition of the present invention forms an adhesive layer by curing it through irradiation with ultraviolet light, and its method of use may involve forming an adhesive layer on a substrate (separator) to produce an adhesive sheet that can be transferred to an adherend, or forming an adhesive layer directly on an adherend.
• a substrate separator
• the number of times of lamination can be minimized and air bubbles can be prevented from entering the interface during lamination.
• the adhesive layer is placed on the adherend by transfer, which has the advantage of fewer constraints on construction.
• the present invention also includes a method for producing a laminate comprising a step of applying the ultraviolet-curable adhesive composition of the present invention onto a first adherend and exposing the composition to light to form an adhesive layer, and a step of attaching a second adherend onto the adhesive layer, the method for applying the ultraviolet-curable adhesive composition being screen printing, stencil printing, or reverse offset printing, and the method for producing a laminate in which the ultraviolet-curable adhesive composition is applied entirely or partially onto the first adherend.
• first adherend and the second adherend examples include metals such as stainless steel and aluminum, and resins.
• first adherend and the second adherend are preferably substrates that have been subjected to a release treatment, and more preferably substrates that have been subjected to a release treatment and an antistatic treatment.
• the ultraviolet-curable pressure-sensitive adhesive composition of the present invention is partially coated on the first adherend.
• the thickness of the adhesive layer is preferably 30 ⁇ m or more. By having a thickness of the adhesive layer of 30 ⁇ m or more, sufficient adhesion can be obtained.
• the thickness of the adhesive layer is more preferably 50 ⁇ m or more.
• the thickness of the adhesive layer is preferably 1000 ⁇ m or less, and more preferably 500 ⁇ m or less.
• the present invention can provide an ultraviolet-curable pressure-sensitive adhesive composition that is excellent in ultraviolet curability in the presence of oxygen, waterproofness and dust resistance, and shape stability after printing, as well as an ultraviolet-curable pressure-sensitive adhesive composition that is excellent in curability when irradiated with high-intensity ultraviolet light in the presence of oxygen, and in adhesion and retention performance after curing.
• the present invention can provide a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.
• Examples 1-1 to 1-35 Comparative Examples 1-1 to 1-4
• a planetary mixer Thinky Corporation, "Awatori Rentaro"
• Tables 1 to 4 Details of the materials indicated by abbreviations in Tables 1 to 4 are as follows.
• the viscosity of the obtained ultraviolet-curable pressure-sensitive adhesive composition was measured at 25°C and 10 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., "TV-22") with an appropriate cone plate according to the composition.
• the viscosity of the obtained ultraviolet-curable pressure-sensitive adhesive composition was also measured at 25°C and 1 rpm, and the viscosity measured at 1 rpm was divided by the viscosity measured at 10 rpm to obtain the thixotropic index (Ti value).
• the results are shown in Tables 1 to 4.
• the obtained ultraviolet-curable pressure-sensitive adhesive composition was applied onto a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 ⁇ m) using an applicator.
• the film was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 in an atmospheric environment using a batch-type UV LED curing device (manufactured by CSS Corporation, "UV-LED PROCESSOR LSS-61”) so that the irradiation amount was 3000 mJ/cm 2 , thereby obtaining a cured product having a thickness of 50 ⁇ m.
• the atmospheric surface was sealed with a release PET film (manufactured by Nippa Corporation, "1-C", thickness 38 ⁇ m) to obtain a laminate.
• both release films were peeled off from the laminate, and about 0.3 g of the cured product of the ultraviolet-curable adhesive composition was placed on an aluminum pan with a diameter of 10 cm and a height of 1 cm, and a mixed solvent containing THF: acetone: ethanol in a mass ratio of 8:1:1 was gently added so that the cured sample would not scatter, and the sample was allowed to swell for about 2 hours. Then, the sample was dried at 110°C for 30 minutes, at 170°C for 1 hour, and at 190°C for 30 minutes.
• reaction rate (%) (total mass of aluminum pan and sample after drying ⁇ mass of aluminum pan before drying)/(mass of sample before swelling) ⁇ 100
• Each of the obtained ultraviolet-curable pressure-sensitive adhesive compositions was applied to the inner treated surface of an easily adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") with an applicator. Thereafter, without sealing the coated surface, the film was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 in an atmospheric environment using a batch-type UV LED curing device (manufactured by CSS, "UV-LED PROCESSOR LSS-61”) so that the irradiation amount was 3000 mJ/ cm2 , thereby obtaining a cured product having a thickness of 50 ⁇ m.
• an easily adhesive polyester film manufactured by Toyobo Co., Ltd., "Cosmoshine A4100
• the film was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 in an atmospheric environment using a
• the illuminance and integrated light amount were measured using an ultraviolet irradiation meter UVR-T2 and a light receiving unit UD-T36T2 (manufactured by TOPCON Corporation).
• the air surface was sealed with a release PET film (manufactured by Nippa, "1-C", thickness 38 ⁇ m), and cut to a width of 25 mm and a length of 200 mm (adhering surface 20 mm ⁇ 125 mm) to prepare a laminated film.
• the release PET film was peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving it back and forth with a 2 kg roller to obtain a test piece.
• the test piece was stored in a 25 ° C.
• a pattern-treated 80-mesh printing plate was used as the screen printing plate.
• the shape of the opening of the screen printing plate was a square with a line width of 1.5 mm, and the dimensions inside the line were a square with one side of 21.5 mm.
• the upper surface of the coating was not sealed and was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 at an exposure dose of 3000 mJ/ cm2 in an atmospheric environment using a batch-type UV LED curing device (manufactured by CSS, "UV-LED PROCESSOR LSS-61”) to obtain a cured product with a thickness of 50 ⁇ m.
• Line width change rate (%) (1-average line width/design line width) ⁇ 100
• the printability (shape stability after printing) was evaluated according to the following criteria. ⁇ : When the absolute value of the line width change rate is less than 5%. ⁇ : When the absolute value of the line width change rate is 5% or more and less than 15%. ⁇ : When the absolute value of the line width change rate is 15% or more. ⁇ : When mesh transmission is impossible or when there is a hole that divides the line.
• the obtained laminate was pressed at 45 N using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310") and allowed to stand for 48 hours in a 25°C environment. Then, a cylinder with an inner diameter of 30 mm and a height of 20 mm with packing on both sides was placed on the opposite side of the surface of the SUS adherend to which the cured product was attached. The laminate with the cylinder placed was sandwiched between acrylic plate A with an air inlet and acrylic plate B with a square hole with a side of 28 mm, and fixed with screws. At this time, the PET film with the cured product attached was made to fit inside the hole of acrylic plate B.
• PET film Highly adhesive polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") Release PET film: PET film with one side release treatment (manufactured by Nippa Corporation, "1-E", thickness 50 ⁇ m)
• SUS-BA plate SUS304-BA plate
• the obtained ultraviolet-curable pressure-sensitive adhesive composition was stencil-printed onto each printing substrate shown in Table 5 using a screen printer (Microtec Corporation, "LABTOP-38").
• the stencil plate was a 55 ⁇ m-thick SUS plate, the shape of the opening was a square with a line width of 1.5 mm, and the dimensions inside the line were a square with one side of 21.5 mm.
• a 0.3 mm-wide bridge was left by half etching to support the SUS plate part inside the pattern.
• the upper surface of the coating was not sealed and was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 at an exposure dose of 3000 mJ/ cm2 in an atmospheric environment using a batch-type UV LED curing device (manufactured by CSS, "UV-LED PROCESSOR LSS-61") to obtain a cured product with a thickness of 50 ⁇ m.
• the line widths of the four sides of the obtained cured product were measured using a microscope (manufactured by KEYENCE Corporation) and the average value was calculated.
• the rate of change of the average measured line width relative to the design line width (1.5 mm) was calculated using the following formula.
• Line width change rate (1-average line width/design line width) ⁇ 100
• the printability was evaluated according to the following criteria. ⁇ : When the absolute value of the line width change rate was less than 5%. ⁇ : When the absolute value of the line width change rate was 5% or more and less than 15%. ⁇ : When the absolute value of the line width change rate was 15% or more. ⁇ : When it was impossible to discharge liquid from the opening.
• Examples 2-1 to 2-28, Comparative Examples 2-1 to 2-4 According to the compounding ratios shown in Tables 6 to 8, each material was mixed with a planetary mixer (Thinky Corporation, "Awatori Rentaro") to obtain each of the ultraviolet-curable pressure-sensitive adhesive compositions of Examples 2-1 to 2-28 and Comparative Examples 2-1 to 2-4. Details of the materials indicated by abbreviations in the table are as follows.
• CHMI N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd., no structure with hydrogen bonded to a heteroatom)
• CHCMA N-(4-carboxycyclohexylmethyl)maleimide (Seiko Chemical Industry Co., Ltd., has a structure in which hydrogen is bonded to a heteroatom)
• HPM 4-hydroxyphenylmaleimide (Seiko Chemical Industry Co., Ltd., has a structure in which hydrogen is bonded to a heteroatom)
• NVC N-vinyl- ⁇ -caprolactam (Tokyo Chemical Industry Co., Ltd.)
• M-140 N-acryloyloxyethylhexahydrophthalimide (manufactured by Toagosei Co., Ltd.)
• NOAA n-octyl acrylate (Osaka Organic Chemical Industry Co., Ltd.)
• CBA Ethyl carbitol
• the obtained ultraviolet-curable adhesive composition was applied onto a release PET film (manufactured by Nippa, "1-E", thickness 50 ⁇ m) using an applicator.
• a batch-type UV LED curing device manufactured by CSS, "UV-LED PROCESSOR LSS-61" was used to irradiate ultraviolet rays having a wavelength of 365 nm and an illuminance of 500 mW/cm 2 so that the irradiation amount was 3000 mJ/cm 2 , thereby obtaining a cured product having a thickness of 50 ⁇ m.
• Example 2-16 After obtaining the laminate, it was aged at 40 ° C. for 48 hours.
• the ultraviolet-curable adhesive composition obtained in Example 2-17 after obtaining the laminate, it was aged at 40 ° C. for 48 hours.
• Each of the obtained ultraviolet-curable pressure-sensitive adhesive compositions was applied to the inner treated surface of an easily adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") with an applicator. Thereafter, without sealing the coated surface, the film was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 in an atmospheric environment using a batch-type UV LED curing device (manufactured by CSS, "UV-LED PROCESSOR LSS-61”) so that the irradiation amount was 3000 mJ/ cm2 , thereby obtaining a cured product having a thickness of 50 ⁇ m.
• an easily adhesive polyester film manufactured by Toyobo Co., Ltd., "Cosmoshine A4100
• the film was irradiated with ultraviolet light having a wavelength of 365 nm and an illuminance of 500 mW/ cm2 in an atmospheric environment using a
• the illuminance and integrated light amount were measured using an ultraviolet irradiation meter UVR-T2 and a light receiving unit UD-T36T2 (manufactured by TOPCON Corporation).
• the air surface was sealed with a release PET film (manufactured by Nippa, "1-C", thickness 38 ⁇ m), and cut to a width of 25 mm and a length of 200 mm (adhering surface 25 mm ⁇ 125 mm) to prepare a laminated film.
• the release PET film was peeled off from the laminated film, and the exposed surface was attached to a SUS substrate and pressed by moving it back and forth with a 2 kg roller to obtain a test piece.
• test piece was stored in a 25 ° C environment for 24 hours, and the 180 ° peel adhesive strength was measured by performing a 180 ° peel at a speed of 300 mm / min using a universal testing machine (manufactured by A & D, "Tensilon RTI-1310").
• the other release PET film (1-E) was peeled off, and the mirror-polished surface of a similar SUS substrate was bonded to the exposed cured product surface, and then pressure-bonded at 215 N using a universal testing machine (manufactured by A&D Co., Ltd., "Tensilon RTI-1310") and left to stand for 48 hours in an environment of 25 ° C. to obtain a test piece.
• the obtained test piece was hung using an S-hook, and further, a weight of 500 g was hung from the lower SUS substrate. This was left at 25° C., and the time until the weight fell was measured, and the retention performance was evaluated according to the following criteria.
• ⁇ The weight did not fall even after 24 hours.
• ⁇ It took 12 hours or more but less than 24 hours for the weight to fall.
• ⁇ It took 1 hour or more but less than 12 hours for the weight to fall.
• ⁇ It took less than 1 hour for the weight to fall.
• UV-LED PROCESSOR LSS-61 manufactured by CSS Co., Ltd.
• ultraviolet rays with a wavelength of 365 nm and an illuminance of 500 mW/cm 2 were irradiated so that the irradiation amount was 3000 mJ/cm 2. This was repeated until the thickness of the cured product was 50 ⁇ m.
• Applicator Examples 2-20 to 2-26, 2-28)
• the obtained ultraviolet-curable pressure-sensitive adhesive composition was applied onto a release PET film (Nippa Corporation's "1-E", thickness 50 ⁇ m) with an applicator.
• the obtained screen-printable composition was screen-printed by applying a pattern to the inner treated surface of an easily adhesive polyester film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100") using a screen printer (manufactured by SERIA Co., Ltd., "SSA-PC560E”).
• a pattern-treated 80-mesh printing plate was used as the screen printing plate.
• a batch-type UV LED curing device manufactured by CSS Co., Ltd., "UV-LED PROCESSOR LSS-61" was used to irradiate ultraviolet light with a wavelength of 365 nm and an illuminance of 500 mW/cm 2 so that the irradiation amount was 3000 mJ/cm 2 , thereby obtaining a cured product with a thickness of 50 ⁇ m.
• the present invention can provide an ultraviolet-curable pressure-sensitive adhesive composition that is excellent in ultraviolet curability in the presence of oxygen, waterproofness and dust resistance, and shape stability after printing, as well as an ultraviolet-curable pressure-sensitive adhesive composition that is excellent in curability when irradiated with high-intensity ultraviolet light in the presence of oxygen, and in adhesion and retention performance after curing.
• the present invention can provide a method for producing a laminate using the ultraviolet-curable pressure-sensitive adhesive composition.

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