JP2015078281A - Adhesive composition, adhesive using the same, adhesive processed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition having no problem such as white turbidness, segregation phenomenon, or bleedout, especially excellent in adhesiveness to a curved surface and followability, and hardly generating lifting or peeling from an adherend, and to provide an adhesive using the same and an adhesive processed product.SOLUTION: There are provided an adhesive composition containing (A) at least one polymer selected from an acrylic random copolymer having an acrylic acid alkyl ester unit and an acrylic single polymer, and (B) an acrylic block copolymer having at least one polymer block B1 mainly containing a methacrylic acid alkyl ester unit and at least one polymer block B2 mainly containing an acrylic acid alkyl ester unit, and a weight average molecular weight (Mw) of at least one polymer block B1 of 10,000 or more, and an adhesive based on the adhesive composition and an adhesive processed product.

Description

  The present invention relates to an adhesive composition, and an adhesive and an adhesive processed product using the same.

  Conventional acrylic adhesives have excellent light resistance (weather resistance), oil resistance, etc., and adhesive properties such as adhesive strength and holding power (cohesive strength), and aging resistance such as heat resistance and light resistance (weather resistance). Widely used because of its excellent properties.

  For example, as a pressure-sensitive adhesive used for optical applications, Patent Document 1 discloses a polymer block A having a pressure-sensitive adhesive polymer mainly composed of an acrylic polymer and an acrylic oligomer having a glass transition temperature of −5 ° C. or less alone. Adhesive having an adhesive layer containing an AB type, ABA type, or BAB type block copolymer comprising a polymer block B having a different monomer composition. A mold optical film is disclosed. It is disclosed that the addition of an acrylic oligomer is suitable as an adhesive layer to be applied to one side of an optical film, and the optical film can be easily peeled off without leaving glue and can be bonded again (rework).

  Patent Document 2 discloses a (meth) acrylate-based single polymer having a number average molecular weight of 500 to 100,000 as a polymer modifier having excellent compatibility with various polymers and an excellent modification effect. A block copolymer of AB type, ABA type or BAB type consisting of a polymer block A consisting of a polymer and a polymer block B having a different monomer composition from the polymer block A It is disclosed. As a modification effect, an effect as a tackifier that improves the tackiness by adding to an acrylic polymer is disclosed.

  These acrylic pressure-sensitive adhesives are widely used as bonding materials in various industrial fields such as home appliances, building materials, and automobile interior / exterior materials. Therefore, it is required to adhere to adherends (joining objects) of various materials and shapes with high reliability.

  However, use of the pressure-sensitive adhesive disclosed in Patent Document 1 is limited to a pressure-sensitive adhesive optical film that can be bonded again, and various polymer modifiers disclosed in Patent Document 2 can be used. There was room for improvement in bonding with high reliability to adherends of different materials and shapes.

JP 2004-58289 A JP 2004-35751 A Japanese Patent Laid-Open No. 06-93060 Japanese National Patent Publication No. 05-507737 JP-A-11-335432

Macromolecular Chemistry and Physics, 2000, 201, p. 1108 to 1114

  Thus, the object of the present invention is to provide a pressure-sensitive adhesive composition that is free from problems such as cloudiness, segregation, and bleed-out, and is particularly excellent in adhesion and followability to curved surfaces and is less likely to lift and peel off from the adherend. And providing an adhesive and an adhesive processed product using the same.

According to the present invention, the above object is
[1] At least one polymer (A) selected from an acrylic random copolymer having an acrylic acid alkyl ester unit and an acrylic homopolymer, and at least one polymer block B1 mainly composed of a methacrylic acid alkyl ester unit And at least one polymer block B2 mainly composed of an acrylic acid alkyl ester unit, and at least one weight average molecular weight (Mw) of the polymer block B1 is 10,000 or more. A pressure-sensitive adhesive composition containing B);
[2] The pressure-sensitive adhesive composition according to [1], wherein the acrylic block copolymer (B) has a weight average molecular weight (Mw) of from 120,000 to 300,000;
[3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the molecular weight distribution (Mw / Mn) of the acrylic block copolymer (B) is less than 1.5;
[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the acrylic random copolymer (A) has a weight average molecular weight (Mw) of more than 300,000 and 3,000,000 or less. object;
[5] A solvent-type pressure-sensitive adhesive obtained by dissolving or dispersing the pressure-sensitive adhesive composition according to any one of [1] to [4] in an organic solvent;
[6] An adhesive processed product having the adhesive composition layer according to any one of [1] to [4];
[7] The pressure-sensitive adhesive product according to [6], wherein the pressure-sensitive adhesive composition layer comprises a laminate formed between a base material layer and an adherend containing a vinyl chloride resin.
Is achieved by providing

  According to the present invention, there is no problem such as white turbidity, segregation phenomenon, bleed-out, etc., and in particular, an adhesive composition excellent in adhesive force and followability to a curved surface and less likely to float and peel off from the adherend, and The used pressure-sensitive adhesive and pressure-sensitive adhesive processed product can be provided.

<Polymer (A) Selected from Acrylic Random Copolymer and Acrylic Homopolymer>
The polymer (A) used in the present invention will be described. This polymer (A) is at least one polymer selected from an acrylic random copolymer and an acrylic homopolymer.

  The acrylic random copolymer is a random copolymer having two or more types of alkyl acrylate units, and a random copolymer having an alkyl acrylate unit and other monomer units other than the alkyl acrylate ester. It is. The acrylic random copolymer can be synthesized by random copolymerization of two or more alkyl acrylate esters or by random copolymerization of an alkyl acrylate ester and a monomer other than the alkyl acrylate ester.

The acrylic homopolymer is a homopolymer composed of one type of acrylic acid alkyl ester unit, and can be synthesized by homopolymerizing an acrylic acid alkyl ester.
Examples of the alkyl acrylate esters include alkyl acrylates having 1 to 20 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, and the like. Etc. Among these acrylic acid alkyl esters, alkyl acrylate esters having an alkyl group having 4 to 9 carbon atoms such as butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and nonyl acrylate are preferable. These alkyl acrylates may be used alone or in combination of two or more.

The average carbon number of the alkyl group contained in the alkyl acrylate unit is usually about 1 to 20, preferably 4 to 9.
When the polymer (A) is an acrylic random copolymer, it may further contain other monomer units other than the acrylic acid alkyl ester.

  Examples of the other monomer units include methyl methacrylate alkyl esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate and nonyl methacrylate; vinyl aromatic units such as styrene. Examples include acrylamide and vinyl acetate.

  As the other monomer unit, a monomer unit having a functional group reactive with a polyfunctional compound that can be included as one component of the pressure sensitive adhesive, such as a carboxyl group, a hydroxyl group, an epoxy group, or the like is included. Is a preferred embodiment.

  Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and N-methylol (meth) acrylamide. Examples of the monomer having an epoxy group include glycidyl (meth) acrylate.

  Content of the monomer unit which has the said functional group in a polymer (A) becomes like this. Preferably it is 5-50 mass%, More preferably, it is 10-30 mass%. Further, when the polymer (A) contains a monomer unit having the above functional group, the content of the acrylic acid alkyl ester unit is preferably 50 to 95% by mass, more preferably 70 to 90% by mass. It is.

  The acrylic random copolymer that is one of the polymers (A) preferably contains an alkyl acrylate unit as a main component. Here, including as a main component means that the polymer (A) contains the most alkyl acrylate units, and the content of the alkyl acrylate units in the polymer (A) is usually 50. -100 mass%, Preferably it is 70-100 mass%, More preferably, it is 90-100 mass%.

  The polymer (A) has a weight average molecular weight (Mw) of preferably more than 300,000 and not more than 3,000,000, more preferably more than 300,000 and not more than 1,000,000, still more preferably 300,000. More than 800,000, particularly preferably more than 350,000 and 600,000 or less. When Mw is larger than 3,000,000, compatibility with the acrylic block copolymer (B) described later is deteriorated, and the improvement effect is not manifested particularly in curved surface adhesion as the performance of the pressure-sensitive adhesive. When Mw is 300,000 or less, the compatibility with the acrylic block copolymer (B) is good, but the cohesive force of the adhesive is insufficient, and the performance required as an adhesive in various industrial fields. May not develop.

  The polymer (A) selected from the acrylic random copolymer and acrylic homopolymer of the present invention may be used alone or in combination of two or more. The polymer (A) selected from the acrylic random copolymer and the acrylic homopolymer is not particularly limited as long as it is a polymer used as a main component of the pressure-sensitive adhesive, and various polymers can be used depending on the purpose of use. Can be used. For example, the polymer (A) may be a polymer synthesized by an ordinary radical polymerization method or a polymer synthesized by a living radical polymerization method. Moreover, you may use the commercially available adhesive containing the polymer (A) chosen from the said acrylic random copolymer and an acrylic homopolymer as it is as the said polymer (A).

<Acrylic block copolymer (B)>
The acrylic block copolymer (B) used in the present invention will be described. The acrylic block copolymer (B) has at least one polymer block B1 mainly composed of an alkyl methacrylate unit. This polymer block B1 can be synthesized by polymerizing a monomer mainly containing a methacrylic acid alkyl ester. Examples of the methacrylic acid alkyl ester as the methacrylic acid alkyl ester unit include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate. , T-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyldecyl methacrylate, etc. Is mentioned.

  Among these alkyl methacrylate esters, from the viewpoint of ensuring the cohesive strength of the polymer block B1, alkyl groups having 1 to 3 carbon atoms such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and the like. Methacrylic acid ester having is preferable, and methyl methacrylate is more preferable.

These alkyl methacrylates may be used alone or in combination of two or more.
The polymer block B1 is characterized by containing a methacrylic acid alkyl ester unit as a main component. The polymer block B1 having a methacrylic acid alkyl ester unit as a main component is a monomer that forms the polymer block B1. This means that among the units, the methacrylic acid alkyl ester unit has the largest mass%. In the polymer block B1, the content of the methacrylic acid alkyl ester unit is preferably 80% by mass to 100% by mass, and more preferably 90% by mass to 100% by mass. Moreover, it is also a preferable aspect of the present invention that the polymer block B1 is composed only of alkyl methacrylate units.

  The polymer block B1 may contain a monomer unit other than the methacrylic acid alkyl ester unit as long as it is in a small amount. Other monomer units can be obtained, for example, by adding this other monomer to the methacrylic acid alkyl ester and then polymerizing it when synthesizing the polymer block B1.

  Examples of other monomers other than methacrylic acid alkyl esters include, for example, methacrylic acid esters other than methacrylic acid alkyl esters such as trimethylsilyl methacrylate, trimethoxysilylpropyl methacrylate, glycidyl methacrylate, and allyl methacrylate; methyl acrylate, acrylic Examples include acrylic acid alkyl esters such as n-butyl acid and t-butyl acrylate; olefins such as ethylene and propylene; and lactones such as ε-caprolactone and valerolactone. These other monomers may be used alone or in combination of two or more. In the polymer block B1, the content of other monomer units is preferably 20% by mass or less, more preferably 10% by mass or less.

  The polymer block B1 is characterized in that at least one weight average molecular weight (Mw) thereof is 10,000 or more. When such a polymer block B1 is contained in the acrylic block copolymer (B), the pressure-sensitive adhesive prepared from the pressure-sensitive adhesive composition of the present invention tends to have excellent curved surface adhesiveness. Although the detailed mechanism is not clear, the pressure-sensitive adhesive composition of the present invention containing such an acrylic block copolymer having the polymer block B1 is compatible with the polymer (A) and has a uniform dispersibility. In addition to improving the cohesive force of the pressure-sensitive adhesive, for example, by forming a physical pseudo-crosslinked structure in the pressure-sensitive adhesive composition, the wettability and initial adhesion to the adherend having a curved surface It is estimated that the force contributes to a suitable range for the curved surface adhesion.

  From the viewpoint of improving curved surface adhesion, the Mw of the polymer block B1 is preferably in the range of 10,000 to 50,000, more preferably in the range of 10,000 to 30,000.

  In addition, when two or more of the polymer blocks B1 are included in the acrylic block copolymer, it is sufficient that at least one of the polymer blocks B1 has the Mw. From the viewpoint that the compatibility with A) is more excellent, it is preferable that all the polymer blocks B1 satisfy the Mw requirement.

The polymer block B1 may be a single polymer block or a combination of two or more polymer blocks.
The acrylic block copolymer (B) has at least one polymer block B2 mainly composed of an acrylic acid alkyl ester unit in addition to the polymer block B1. The polymer block B2 can be synthesized by polymerizing a monomer mainly containing an acrylic acid alkyl ester.

  By including the polymer block B2 mainly composed of an acrylic acid alkyl ester unit in the acrylic block copolymer (B), not only the compatibility with the polymer (A) is excellent, but also the present invention. The wettability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition to the adherend and the initial adhesive force tend to be improved, and the curved-surface adhesive force can be improved.

  Examples of the alkyl acrylate ester to be the acrylic acid alkyl ester unit include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, Examples thereof include t-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate.

  Among these acrylic acid alkyl esters, from the viewpoint of improving curved surface adhesion, n-butyl acrylate, 2-ethylhexyl acrylate, and a combination of n-butyl acrylate and 2-ethylhexyl acrylate are preferable.

These alkyl acrylates may be used alone or in combination of two or more.
The polymer block B2 is characterized by containing an alkyl acrylate ester unit as a main component, but the polymer block B2 having an alkyl acrylate unit as a main component is a monomer that forms the polymer block B2. It means that the acrylic acid alkyl ester unit has the largest mass%. In polymer block B2, the content of alkyl acrylate units is preferably 80% by mass to 100% by mass, more preferably 90% by mass to 100% by mass. Moreover, it is also a preferable aspect of the present invention that the polymer block B2 is composed only of an acrylic acid alkyl ester unit.

  The polymer block B2 may contain other monomer units other than the acrylic acid alkyl ester unit as long as the amount is small. Other monomer units can be obtained, for example, by adding this other monomer to the alkyl acrylate and then polymerizing it when synthesizing the polymer block B2.

  Examples of monomers other than alkyl acrylate esters include acrylic acid esters other than alkyl acrylate esters such as trimethylsilyl acrylate, trimethoxysilyl propyl acrylate, glycidyl acrylate, and allyl acrylate; methyl methacrylate, methacrylic acid Examples include methacrylic acid alkyl esters such as n-butyl acid and t-butyl methacrylate; olefins such as ethylene and propylene; and lactones such as ε-caprolactone and valerolactone. These other monomers may be used alone or in combination of two or more. In the polymer block B2, the content of other monomer units is preferably 20% by mass or less, more preferably 10% by mass or less.

  The polymer block B2 has a weight average molecular weight (Mw) of preferably 15,000 to 150,000, more preferably 25,000 to 120,000. In addition, when the acrylic block copolymer contains two or more polymer blocks B2, it is preferable that all these polymer blocks B2 have the above Mw.

The polymer block B2 may be a single polymer block or a combination of two or more polymer blocks.
The weight average molecular weight (Mw) of the entire acrylic block copolymer (B) is preferably from 50,000 to 300,000, more preferably from 120,000 to 300,000, 140, More preferably, it is 000-200,000. When the weight average molecular weight exceeds 300,000, compatibility with the polymer (A) may be deteriorated, and when the weight average molecular weight is less than 120,000, the curved surface contact of the pressure-sensitive adhesive composition of the present invention. There may be cases where desired performance cannot be obtained in terms of adhesion.

  The number average molecular weight (Mn) of the entire acrylic block copolymer (B) is preferably more than 45,000 and not more than 300,000, more preferably more than 100,000 and not more than 300,000. More preferably, it is larger than 120,000 and not larger than 300,000. When the number average molecular weight of the acrylic block copolymer (B) is in the above range, the compatibility with the polymer (A) is good, and in the curved surface adhesive strength of the pressure-sensitive adhesive composition of the present invention, Desired performance can be obtained.

  The molecular weight distribution (Mw / Mn) of the acrylic block copolymer (B) is preferably less than 1.5. When the molecular weight distribution (Mw / Mn) of the acrylic block copolymer (B) is 1.5 or more, the influence of low molecular weight components cannot be ignored, and problems such as a decrease in cohesive force and adhesive residue are likely to occur. . Mw / Mn of the acrylic block copolymer (B) is 1.0 to 1.4 from the point that the cohesive force at high temperature of the pressure-sensitive adhesive composition is high and the curved surface adhesive force is excellent. Is more preferable, 1.0 to 1.3 is more preferable, and 1.0 to 1.2 is further more preferable.

  In the acrylic block copolymer (B), when the ratio of the total mass of the polymer block B1 based on the total mass of the polymer block B2 contained is too small, the cohesive force of the pressure-sensitive adhesive composition of the present invention is increased. It tends to be small and the holding force (shear creep strength) tends to be low. On the other hand, if the ratio of the total weight of the polymer block B1 based on the total mass of the polymer block B2 is too large, the pressure-sensitive adhesive composition has insufficient adhesive strength and is compatible with the polymer (A). There is a tendency to get worse. From these points, the ratio of the total mass of the polymer block B1 and the total mass of the polymer block B2 contained in the molecule of the acrylic block copolymer (B) is 5 / B2. The range is preferably from 95 to 55/45, and more preferably from 10/85 to 35/65.

  The manufacturing method of the said acrylic block copolymer (B) used for this invention is not specifically limited as long as the polymer which satisfies the said conditions is obtained, For example, the method according to a well-known method is employable. In general, as a method for obtaining a block copolymer having a narrow molecular weight distribution, a method of living polymerizing monomers as constituent units is employed. Examples of such living polymerization methods include a method of living polymerization using an organic rare earth metal complex as a polymerization initiator (see Patent Document 3), an alkali metal or alkaline earth metal salt using an organic alkali metal compound as a polymerization initiator, and the like. A living anion polymerization in the presence of a mineral acid salt (see Patent Document 4), a living anion polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organoaluminum compound (see Patent Document 5), atoms Examples thereof include a moving radical polymerization method (ATRP) (see Non-Patent Document 1).

  Among the above production methods, the method of living anion polymerization using an organoalkali metal compound as a polymerization initiator in the presence of an organoaluminum compound makes the resulting block copolymer highly transparent, has little residual monomer and has an odor. In addition, when used as a pressure-sensitive adhesive composition, the generation of bubbles after bonding can be suppressed, which is preferable. Furthermore, the molecular structure of the methacrylate ester polymer block is highly syndiotactic, which has the effect of increasing the heat resistance of the pressure-sensitive adhesive composition, and is capable of living polymerization under relatively mild temperature conditions and industrially produced. In this case, the environmental load (mainly the electric power applied to the refrigerator for controlling the polymerization temperature) is also small.

As the organoaluminum compound, for example, the following general formula (IV)
AlR ¹ R ² R ³ (IV)
(Wherein R ¹ , R ² and R ³ are each independently an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or an aryl which may have a substituent) A group, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent or an N, N-disubstituted amino group, or R ¹ is any of the groups described above, and R ² and R ³ are combined to form an aryleneoxy group which may have a substituent.
The organoaluminum compound represented by these is mentioned.

  As the organoaluminum compound represented by the general formula (IV), isobutylbis (2,6-ditert-butyl-4-methylphenoxy) aluminum is used from the viewpoint of high living property of polymerization and easy handling. And isobutylbis (2,6-ditert-butylphenoxy) aluminum, isobutyl [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum and the like are preferable.

  Examples of the organic alkali metal compound include n-butyllithium, sec-butyllithium, isobutyllithium, tert-butyllithium, n-pentyllithium, and alkyldilithium such as tetramethylenedilithium; phenyllithium, p- Aryllithium and aryldilithium such as tolyllithium and lithium naphthalene; aralkyllithium and aralkyldilithium such as dilithium produced by the reaction of benzyllithium, diphenylmethyllithium, diisopropenylbenzene and butyllithium; lithium amide such as lithium dimethylamide And lithium alkoxides such as methoxylithium and ethoxylithium. These may be used alone or in combination of two or more. Of these, alkyl lithium is preferable because of high polymerization initiation efficiency, among which tert-butyl lithium and sec-butyl lithium are more preferable, and sec-butyl lithium is more preferable.

  The living anionic polymerization may be carried out in the reaction system as required by an ether compound such as dimethyl ether, dimethoxyethane, diethoxyethane, 12-crown-4; triethylamine, N, N, N ′, N′-tetramethylethylenediamine, Nitrogen-containing compounds such as N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, pyridine, 2,2′-dipyridyl Can be further added. When these compounds are added, the polymerization rate and living polymerizability increase, and a high molecular weight block copolymer having a smaller molecular weight distribution can be obtained.

  The living anion polymerization is usually performed in the presence of a solvent inert to the polymerization reaction. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloroform, methylene chloride, and carbon tetrachloride; ether compounds such as tetrahydrofuran and diethyl ether.

  The acrylic block copolymer (B) used in the present invention has, for example, an acrylic acid alkyl ester at the end of a desired living polymer (polymer block B1) obtained by polymerizing a monomer mainly containing an alkyl methacrylate. Is polymerized to form a polymer block B2, and a process of forming another desired polymer block (for example, polymer block B1) is repeated a desired number of times, followed by polymerization. It can be produced by stopping the reaction. Before forming the polymer block B1, a step of forming a desired polymer block may be included. The acrylic block copolymer (B) can be produced by reacting the active terminal of the obtained polymer with alcohol or the like through such a multi-step polymerization process and stopping the polymerization reaction.

  The polymerization temperature is 0 to 100 ° C. when a monomer mainly containing methacrylic acid alkyl ester is polymerized (for example, when forming polymer block B1), and a monomer mainly containing acrylic acid alkyl ester is polymerized. When performing (for example, when forming polymer block B2), -50-50 degreeC is preferable. When the polymerization temperature is lower than the above range, the progress of the reaction is slow, and it takes a long time to complete the reaction. On the other hand, when the polymerization temperature is higher than the above range, the deactivation of the living polymer ends increases, the molecular weight distribution becomes wide, and the desired block copolymer cannot be obtained.

  The pressure-sensitive adhesive composition of the present invention contains at least one polymer (A) selected from the acrylic random copolymer and acrylic homopolymer, and an acrylic block copolymer (B) as essential components. . The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention containing these two types of polymers has good compatibility with these polymers and excellent uniform dispersibility, cohesion, wettability to the adherend and Since the initial adhesive force can be in a suitable range for an adherend having a curved surface, curved surface adhesion is improved. The pressure-sensitive adhesive composition of the present invention preferably contains 1 to 100 parts by mass of the acrylic block copolymer (B) with respect to 100 parts by mass of the polymer (A) from the viewpoint of improving curved surface adhesion. It is more preferable to have -70 mass parts, and it is still more preferable to have 10-40 mass parts.

  The pressure-sensitive adhesive composition of the present invention may comprise only at least one polymer (A) and acrylic block copolymer (B) selected from the acrylic random copolymers and acrylic homopolymers. In order to impart desired physical properties, other components may be further contained.

Examples of other components that can be included in the pressure-sensitive adhesive composition include tackifier resins, plasticizers, other polymers, and crosslinking agents.
For example, by adding a tackifier resin to the above-mentioned pressure-sensitive adhesive composition, tack, pressure-sensitive adhesive force and holding power, which are the three elements of the pressure-sensitive adhesive, can be adjusted to a desired range. Examples of the tackifying resin include rosin resins such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin; terpene resin mainly composed of terpene phenol resin, α-pinene, β-pinene, limonene (Hydrogenated) petroleum resin, coumarone-indene resin, hydrogenated aromatic copolymer, styrene resin, phenol resin, xylene resin and the like. These tackifier resins may be used alone or in combination of two or more. The content of the tackifying resin in the pressure-sensitive adhesive composition can be appropriately selected according to the type of tackifying resin, the type of adherend, etc., but from the viewpoints of tackiness, removability, etc. 5-100 mass parts is preferable with respect to a total of 100 mass parts of union (A) and acrylic block copolymer (B), 10-60 mass parts is more preferable, and 20-40 mass parts is more preferable.

  Examples of the plasticizer include phthalic acid esters such as dibutyl phthalate, di n-octyl phthalate, bis 2-ethylhexyl phthalate, di n-decyl phthalate and diisodecyl phthalate; adipine such as bis 2-ethylhexyl adipate and di n-octyl adipate Acid esters; sebacic acid esters such as bis-2-ethylhexyl sebacate and di-n-butyl sebacate; fatty acid esters such as azelaic acid esters such as bis-2-ethylhexyl azelate; paraffins such as chlorinated paraffin; epoxidized soybean oil, epoxidized Epoxy polymer plasticizers such as linseed oil; Phosphate esters such as trioctyl phosphate and triphenyl phosphate; Phosphites such as triphenyl phosphite; Poly (meth) acrylic acid -Acrylic oligomers such as butyl and 2-ethylhexyl poly (meth) acrylate; polybutene; polyisobutylene; polyisoprene; process oil; naphthenic oil; polyester polyol, polyether polyol; polyalkylene glycol such as polyethylene glycol and polypropylene glycol Polyol compounds and the like. These plasticizers may be used alone or in combination of two or more. The content of the plasticizer in the pressure-sensitive adhesive composition can be appropriately selected according to the type of plasticizer, the type of adherend, etc., but from the viewpoint of adhesiveness, cohesive strength, compatibility, etc. 5-100 mass parts is preferable with respect to 100 mass parts in total of the polymer (A) chosen from an acrylic random copolymer and an acrylic homopolymer, and an acrylic block copolymer (B), 5-50 A mass part is more preferable and 5-30 mass parts is still more preferable.

  Said other polymer can be included in the range which does not impair the effect of this invention. Examples of other polymers include EPR, EPDM, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and polyvinyl acetate.

  The said crosslinking agent can be included in the range which does not impair the effect of this invention. Examples of the crosslinking agent include an isocyanate crosslinking agent and an epoxy crosslinking agent. Examples of the isocyanate-based crosslinking agent include aliphatic isocyanate compounds, alicyclic isocyanate compounds, aromatic isocyanate compounds, polyisocyanate compound adducts, isocyanurate adducts, and the like. Specific examples of the isocyanate compound that can be used in the pressure-sensitive adhesive composition of the present invention include aliphatic diisocyanate compounds such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic diisocyanate compounds such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; Aromatic diisocyanate compounds such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct, trimethylolpropane / hexamethylene diisocyanate trimer addition Polyisocyanate compounds in which a diisocyanate compound is added to a polyol such as a product; hexamethylene diisocyanate Etc. and an isocyanate adducts such as isocyanurate body.

  Examples of the epoxy crosslinking agent include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl. Examples thereof include polyfunctional epoxy compounds such as ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutadiene diglycidyl ether.

  The cross-linking agent may be added after preparing the pressure-sensitive adhesive from the pressure-sensitive adhesive composition of the present invention and before applying it to the adherend. The said crosslinking agent can be used individually or in combination of 2 or more types.

  The amount of the crosslinking agent contained in the pressure-sensitive adhesive composition varies depending on the type of the crosslinking agent. For example, in the case of an isocyanate-based crosslinking agent, the total of the polymer (A) and the acrylic block copolymer (B). It is preferable that it is 0.01-20 mass parts with respect to 100 mass parts, and it is more preferable that it is 0.01-10 mass parts. If it is the said range, the adhesiveness of an adhesive and a to-be-adhered body can be improved. If it is less than 0.01 part by mass, the adhesiveness between the pressure-sensitive adhesive and the adherend becomes insufficient, and the desired curved surface adhesion may not be obtained. If it exceeds 20 parts by mass, it remains as an unreacted monomer in the pressure-sensitive adhesive layer, and the cohesive force may be reduced.

  Moreover, in the case of an epoxy-type crosslinking agent, it is preferable that it is 0.01-20 mass parts with respect to a total of 100 mass parts of the said polymer (A) and an acryl-type block copolymer (B), 0 More preferably, the content is 0.01 to 10 parts by mass. If it is the said range, the adhesive force and cohesion force before energy ray irradiation can be controlled to desired intensity | strength. If it is less than 0.01 part by mass, the adhesiveness between the pressure-sensitive adhesive and the adherend becomes insufficient, and the desired curved surface adhesion may not be obtained. When the amount exceeds 20 parts by mass, the adhesive force before energy beam irradiation is reduced, and thus chip fly may occur during dicing or the like.

  Moreover, the pressure-sensitive adhesive composition of the present invention may further contain various additives as required. Examples of additives include antioxidants or ultraviolet absorbers added to further improve weather resistance, heat resistance, and oxidation resistance; inorganic powder fillers such as calcium carbonate, titanium oxide, mica, and talc; glass Examples thereof include fibrous fillers such as fibers and organic reinforcing fibers; lubricants and the like.

<Adhesive>
The pressure-sensitive adhesive composition of the present invention may be used as a solution-type pressure-sensitive adhesive or a hot-melt type solid pressure-sensitive adhesive. In the case of a solution-type pressure-sensitive adhesive, the pressure-sensitive adhesive composition or each component of the pressure-sensitive adhesive composition of the present invention can be prepared by dissolving it in an organic solvent such as toluene, ethyl acetate, butyl acetate, or methyl ethyl ketone. it can.

  When used as a hot-melt type solid pressure-sensitive adhesive, each of the pressure-sensitive adhesive compositions is usually in a temperature range of 100 ° C. to 250 ° C. using a kneader such as a kneader ruder, an extruder, a mixing roll, or a Banbury mixer. It can be prepared by mixing the ingredients.

  Among these, the adhesive composition of the present invention is a solution-type pressure-sensitive adhesive from the viewpoint of having a high-reliability pressure-sensitive adhesive that has excellent adhesion and followability to curved surfaces and is less likely to lift and peel off the adherend. It is preferable to be used as

  Since the pressure-sensitive adhesive composition of the present invention contains the block copolymer (B) having a lower molecular weight as an essential component than the acrylic polymer (A) used alone, the solid content when dissolved in an organic solvent. Even at high concentrations, it exhibits low solution viscosity. Therefore, while reducing the amount of organic solvent used, it is possible to obtain a solution-type pressure-sensitive adhesive having a solid content concentration higher than before (for example, a solution-type pressure-sensitive adhesive having a solid content concentration of 35% by mass or more), thereby reducing the drying load. Excellent process properties such as improved coating speed and omission of curing process. Further, the solution-type pressure-sensitive adhesive of the solid content is excellent in handling at the time of coating despite the high solid content concentration. The viscosity of the solution when preparing a solution-type pressure-sensitive adhesive from the pressure-sensitive adhesive composition is preferably in the range of 500 to 5000 mPa · s, more preferably in the range of 1000 to 4000 mPa · s, and still more preferably in the range of 1000 to 3000. .

  From the viewpoint of coating properties, handleability, processability, etc. of the solution-type pressure-sensitive adhesive, when the solution-type pressure-sensitive adhesive is used, the content of the pressure-sensitive adhesive composition of the present invention is based on the mass of the solution-type pressure-sensitive adhesive It is preferable to set it as 20-50 mass%, and it is more preferable to set it as 30-40 mass%.

<Adhesive processed products>
The pressure-sensitive adhesive processed product having the pressure-sensitive adhesive composition layer of the present invention usually includes a substrate made of paper, cloth, or various plastics, and a pressure-sensitive adhesive composition layer. Examples of the above-mentioned pressure-sensitive adhesive products include packaging or office pressure-sensitive adhesive tapes, masking tapes for curing or coating, stainless steel plates, surface protection tapes for preventing damage to resin plates, electrical insulating pressure-sensitive adhesive tapes, electric / electronic Examples include pressure-sensitive adhesive tapes for equipment, pressure-sensitive adhesive tapes for identification such as marking films, adhesive bandages, medical pressure-sensitive adhesive products containing a transdermal absorbent, labels, pressure-sensitive adhesive sheets for sealing, tapes for construction or building materials.

  For example, vinyl chloride resin is relatively often used as a plastic material having excellent durability and corrosion resistance in the construction and building materials fields. Also, a vinyl chloride resin having a long product life is suitably used for various display boards, pipes for water and sewage, rain gutters, electric cables and flooring materials. Many of these products are formed into a curved shape, and a label and an adhesive sheet for sealing are attached to the curved shaped product for various indications. As the pressure-sensitive adhesive used for this pressure-sensitive adhesive sheet, an acrylic pressure-sensitive adhesive having good compatibility with the vinyl chloride resin is generally used. When a pressure-sensitive adhesive label or seal is used for a curved molded article, a characteristic required for a pressure-sensitive adhesive is curved surface adhesiveness. A pressure-sensitive adhesive having a high curved surface adhesion is preferably used because it is less likely to cause problems such as peeling off and floating after the pressure-sensitive adhesive sheet is applied. The pressure-sensitive adhesive composition of the present invention is excellent in pressure-sensitive adhesive force and followability to a curved molded article made of a vinyl chloride resin, and is a highly reliable pressure-sensitive adhesive that is unlikely to be lifted or peeled off from the adherend.

EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further in detail, this invention is not limited at all by this Example.
In the following synthesis examples, chemicals dried and purified by a conventional method were used.
The following methods were used to measure the molecular weight, molecular weight distribution, composition, glass transition temperature and polymerization conversion rate of each polymer block synthesized in the following synthesis examples.

(1) Number average molecular weight (Mn), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn)
It calculated | required as a value of standard polystyrene conversion by the gel permeation chromatography (GPC) on the following conditions.
Apparatus: Gel permeation chromatograph (HLC-8020) manufactured by Tosoh Corporation
-Column: "TSKgel GMHXL, G4000HXL" and "G5000HXL" manufactured by Tosoh Corporation are connected in series.-Eluent: Tetrahydrofuran-Elution flow rate: 1.0 ml / min-Column temperature: 40 ° C
・ Detection method: Differential refractive index (RI)
-Calibration curve: created using standard polystyrene

(2) Content of each copolymer component in each copolymer
^It was determined by ¹ H-NMR spectroscopy.
・ Device: JEOL nuclear magnetic resonance apparatus (JNM-LA400)
-Solvent: deuterated chloroform-In ¹ H-NMR spectrum, signals near 3.6 ppm and 4.0 ppm are respectively the ester groups (-O-C H ₃ ) of methyl methacrylate units and n-butyl acrylate units. is attributed to an ester group _{(-O-C H 2 -CH 2} -CH 2 -CH 3), was determined the content of the copolymerization component by the ratio of the integrated value.

(5) Polymerization conversion rate Determined by gas chromatography (GC).
・ Equipment: Gas chromatograph GC-14A manufactured by Shimadzu Corporation
Column: GL Sciences Inc. “INERT CAP 1” (df = 0.4 μm, 0.25 mm ID × 60 m)
・ Analysis conditions: injection 300 ° C., detector 300 ° C., 60 ° C. (0 minute hold) → temperature rise at 5 ° C./minute→100° C. (0 minute hold) → temperature rise at 15 ° C./minute→300° C. (2 minute hold)

<< Synthesis Example 1 >> [Synthesis of Acrylic Random Copolymer (A-1)]
In a four-necked flask substituted with nitrogen, 96 parts by mass of n-butyl acrylate and 4 parts by mass of acrylic acid were copolymerized in 30 parts by mass of 50:50 solvent of ethyl acetate and toluene, and the weight average molecular weight (Mw). An acrylic random copolymer (A-1) solution of 550,000 was obtained. Ethyl acetate was added thereto to obtain a solution containing 45% by weight of the acrylic random copolymer (A-1).

<< Synthesis Example 2 >> [Synthesis of Acrylic Triblock Copolymer (B-1)]
(1) After replacing the inside of a 2 L three-necked flask with nitrogen, 977 g of toluene and 50.1 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutyl bis (2,6-di-t-butyl-4 -Methylphenoxy) 60 g of a toluene solution containing 5.00 mmol of aluminum was added, and 2.50 mmol of sec-butyllithium was further added. Next, 30.1 g of methyl methacrylate was added to this mixed solution. The reaction mixture initially colored yellow, but became colorless after stirring at room temperature for 60 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Next, the reaction mixture was cooled to −30 ° C., and 185.8 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of n-butyl acrylate was 99.9% or more. To this reaction mixture was further added 12.9 g of methyl methacrylate, and after stirring overnight at room temperature, 4.6 g of methanol was added to terminate the polymerization reaction. At this time, the polymerization conversion rate of methyl methacrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. The white precipitate was collected by filtration and dried to obtain a block copolymer composed of PMMA-PnBA-PMMA [hereinafter referred to as “acrylic triblock copolymer (B-1)”] 257.2 g Got.

(2) As a result of performing ¹ H-NMR measurement and GPC measurement on the acrylic triblock copolymer (B-1), it is a triblock copolymer, and its weight average molecular weight (Mw) is 151,000, number average. The molecular weight (Mn) was 127,000, and the molecular weight distribution (Mw / Mn) was 1.19. In addition, a polymer block having a weight average molecular weight (Mw) of 21,500 from these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of a sample sampled in the middle of polymerization. Was found to be included as polymer block B1. Further, the content of each polymer block was 28.5 mass% for the methyl methacrylate polymer block (polymer block B1) and 71.5 mass for the n-butyl acrylate polymer block (polymer block B2). %Met. The results are shown in Table 1.

<< Synthesis Example 3 >> [Synthesis of Acrylic Triblock Copolymer (B-2)]
(1) After replacing the inside of the 2 L capacity three-necked flask with nitrogen, 1048 g of toluene and 52.4 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutylbis (2,6-di-t-butyl-4- 50.0 g of a toluene solution containing 10.9 mmol of methylphenoxy) aluminum was added, and 2.31 mmol of sec-butyllithium was further added. Next, 18.0 g of methyl methacrylate was added thereto. The reaction mixture initially colored yellow, but became colorless after stirring at room temperature for 60 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Next, the reaction mixture was cooled to −30 ° C., and 221.2 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of n-butyl acrylate was 99.9% or more. To this reaction mixture, 24.5 g of methyl methacrylate was further added, and after stirring overnight at room temperature, 13.0 g of methanol was added to terminate the polymerization reaction. At this time, the polymerization conversion rate of methyl methacrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. The white precipitate was collected by filtration and dried to obtain 262 g of a block copolymer composed of PMMA-PnBA-PMMA (hereinafter referred to as “acrylic triblock copolymer (B-2)”). It was.

(2) As a result of performing ¹ H-NMR measurement and GPC measurement on the acrylic triblock copolymer (B-2), it is a triblock copolymer, and its weight average molecular weight (Mw) is 155,000, number average. The molecular weight (Mn) was 135,600, and the molecular weight distribution (Mw / Mn) was 1.14. In addition, a polymer block having a weight average molecular weight (Mw) of 12,500 from these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of a sample sampled in the middle of polymerization. Was found to be included as polymer block B1. Further, the content of each polymer block was 16.1% by mass for the methyl methacrylate polymer block (polymer block B1) and 83.9 for the n-butyl acrylate polymer block B2 (polymer block B2). It was mass%. The results are shown in Table 1.

<< Synthesis Example 4 >> [Synthesis of Acrylic Triblock Copolymer (B-3)]
(1) After replacing the inside of a 2 L three-necked flask with nitrogen, 1040 g of toluene and 100 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutylbis (2,6-di-t-butyl-4-methyl 45 g of a toluene solution containing 30 mmol of phenoxy) aluminum was added, followed by 7.3 mmol of sec-butyllithium. Next, 64 g of methyl methacrylate was added thereto. The reaction mixture initially colored yellow, but became colorless after stirring at room temperature for 60 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Next, the reaction mixture was cooled to −30 ° C., and 184 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of n-butyl acrylate was 99.9% or more. To this reaction mixture, 161 g of methyl methacrylate was further added, and after stirring overnight at room temperature, 4 g of methanol was added to terminate the polymerization reaction. At this time, the polymerization conversion rate of methyl methacrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. The white precipitate was collected by filtration and dried to obtain 417 g of a block copolymer composed of PMMA-PnBA-PMMA (hereinafter referred to as “acrylic triblock copolymer (B-3)”). It was.

(2) As a result of performing ¹ H-NMR measurement and GPC measurement on the acrylic triblock copolymer (B-3), it is a triblock copolymer, and the weight average molecular weight (Mw) is 62,000, number average. The molecular weight (Mn) was 57,400, and the molecular weight distribution (Mw / Mn) was 1.08. In addition, a polymer block having a weight average molecular weight (Mw) of 15,500 from these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of a sample sampled in the middle of polymerization. Was found to be included as polymer block B1. Further, the content of each polymer block was 50% by mass for the methyl methacrylate polymer block (polymer block B1) and 50% by mass for the n-butyl acrylate polymer block B2 (polymer block B2). It was. The results are shown in Table 1.

<< Synthesis Example 5 >> [Synthesis of Acrylic Diblock Copolymer (B-4)]
(1) After replacing the inside of a 0.5 L three-necked flask with nitrogen, 245 g of toluene and 12.2 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutyl bis (2,6-di-t-butyl- 29.0 g of a toluene solution containing 13.0 mmol of 4-methylphenoxy) aluminum was added, and 1.27 mmol of sec-butyllithium was further added. Next, 30.3 g of methyl methacrylate was added thereto. The reaction mixture was initially colored yellow, but became colorless after 60 minutes of stirring at room temperature. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 31.2 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes, and 1.67 g of methanol was added. The polymerization reaction was stopped by adding. At this time, the polymerization conversion rate of n-butyl acrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. The white precipitate was collected and dried to obtain 61.2 g of a diblock copolymer composed of PMMA-PnBA (hereinafter referred to as “acrylic diblock copolymer (B-4)”).

(2) As a result of ¹ H-NMR measurement and GPC measurement for the acrylic diblock copolymer (B-4), the weight average molecular weight (Mw) was 58,500, and the number average molecular weight (Mn) was 39,800. And the molecular weight distribution (Mw / Mn) was 1.47. In addition, a polymer block having a weight average molecular weight (Mw) of 29,300 based on these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of a sample sampled in the middle of polymerization. Was found to be included as polymer block B1. Further, the content ratio of each polymer block was 50.1 mass% for the methyl methacrylate polymer block (polymer block B1) and 49.9 mass for the n-butyl acrylate polymer block (polymer block B2). %Met. The results are shown in Table 1.

<< Synthesis Example 6 >> [Synthesis of Acrylic Triblock Copolymer (B-5)]
(1) After replacing the inside of a 2 L three-necked flask with nitrogen, 868 g of toluene and 43.4 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutyl bis (2,6-di-t-butyl-4 -Methylphenoxy) 60.0 g of a toluene solution containing 40.2 mmol of aluminum was added, and 5.00 mmol of sec-butyllithium was further added. Next, 35.9 g of methyl methacrylate was added thereto. The reaction mixture initially colored yellow, but became colorless after stirring at room temperature for 60 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Next, the reaction mixture was cooled to −30 ° C., 240 g of n-butyl acrylate was added dropwise over 2 hours, and after completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of n-butyl acrylate was 99.9% or more. To this reaction mixture, 35.9 g of methyl methacrylate was further added, and after stirring overnight at room temperature, 3.50 g of methanol was added to terminate the polymerization reaction. At this time, the polymerization conversion rate of methyl methacrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. The white precipitate was collected by filtration and dried to obtain 255 g of a block copolymer composed of PMMA-PnBA-PMMA (hereinafter referred to as “acrylic triblock copolymer (B-5)”). It was.

(2) As a result of ¹ H-NMR measurement and GPC measurement of the acrylic triblock copolymer (B-5), it is a triblock copolymer, and the weight average molecular weight (Mw) is 78,400, number average. The molecular weight (Mn) was 72,600, and the molecular weight distribution (Mw / Mn) was 1.08. Further, ¹ H-NMR measurement of a sample sampled in the middle of these analysis results and polymerization step, GPC measurement, the charged amount and MMA conversion of MMA, polymer block weight average molecular weight (Mw) of 9,200 Was found to be included as polymer block B1. Further, the content of each polymer block was 23.5 mass% for the methyl methacrylate polymer block (polymer block B1) and 76.5 mass for the n-butyl acrylate polymer block (polymer block B2). %Met. The results are shown in Table 1.

<< Synthesis Example 7 >> [Synthesis of Acrylic Triblock Copolymer (B-6)]
(1) After replacing the inside of a 2 L three-necked flask with nitrogen, 1040 g of toluene and 100 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutylbis (2,6-di-t-butyl-4-methyl 48 g of a toluene solution containing 32 mmol of phenoxy) aluminum was added, and 8.1 mmol of sec-butyllithium was further added. Next, 72 g of methyl methacrylate was added thereto. The reaction mixture initially colored yellow, but became colorless after stirring at room temperature for 60 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Next, the reaction mixture was cooled to −30 ° C., and 307 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of n-butyl acrylate was 99.9% or more. To this reaction mixture, 72 g of methyl methacrylate was further added, and after stirring overnight at room temperature, 4 g of methanol was added to terminate the polymerization reaction. At this time, the polymerization conversion rate of methyl methacrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate a white precipitate. A white precipitate was collected by filtration and dried to obtain 442 g of a block copolymer composed of PMMA-PnBA-PMMA [hereinafter referred to as “acrylic triblock copolymer (B-6)”]. It was.

(2) As a result of performing ¹ H-NMR measurement and GPC measurement on the acrylic triblock copolymer (B-6), it is a triblock copolymer, and its weight average molecular weight (Mw) is 62,000, number average. The molecular weight (Mn) was 52,100, and the molecular weight distribution (Mw / Mn) was 1.19. Further, from these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of the sample sampled in the middle of polymerization, a polymer block having a weight average molecular weight (Mw) of 9,900 Was found to be included as polymer block B1. Further, the content of each polymer block was 32% by mass for the methyl methacrylate polymer block (polymer block B1) and 68% by mass for the n-butyl acrylate polymer block B2 (polymer block B2). It was. The results are shown in Table 1.

<< Synthesis Example 8 >> [Synthesis of Acrylic Diblock Copolymer (B-7)]
(1) After replacing the inside of the 2 L three-necked flask with nitrogen, 870 g of toluene and 44.0 g of 1,2-dimethoxyethane were added at room temperature, followed by isobutyl bis (2,6-di-t-butyl-4- 30.9 g of a toluene solution containing 20.7 mmol of methylphenoxy) aluminum was added, and 5.17 mmol of sec-butyllithium was further added. Next, 21.7 g of methyl methacrylate was added thereto. The reaction mixture was initially colored yellow, but became colorless after 60 minutes of stirring at room temperature. The reaction mixture at this time was sampled and each measurement was performed. The polymerization conversion rate of methyl methacrylate was 99.9% or more. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 288.4 g of n-butyl acrylate was added dropwise over 2 hours. After completion of the addition, the mixture was stirred at −30 ° C. for 5 minutes, and then 3.5 g of methanol was added. The polymerization reaction was stopped by adding. At this time, the polymerization conversion rate of n-butyl acrylate was 99.9% or more. The obtained reaction solution was poured into 15 kg of methanol to precipitate an oily precipitate. The oily precipitate was collected and dried to obtain 310.0 g of a diblock copolymer composed of PMMA-PnBA (hereinafter referred to as “acrylic diblock copolymer (B-7)”).

(2) As a result of ¹ H-NMR measurement and GPC measurement of the acrylic diblock copolymer (B-7), the weight average molecular weight (Mw) was 67,000, and the number average molecular weight (Mn) was 55,400. And the molecular weight distribution (Mw / Mn) was 1.21. Moreover, the polymer block whose weight average molecular weight (Mw) is 4,600 from these analysis results and ¹ H-NMR measurement, GPC measurement, MMA charge amount and MMA conversion rate of the sample sampled in the middle of polymerization. Was found to be included as polymer block B1. Furthermore, the content ratio of each polymer block was 6.9% by mass for the methyl methacrylate polymer block (polymer block B1) and 93.1% for the n-butyl acrylate polymer block (polymer block B2). %Met. The results are shown in Table 1.

Example 1
(1) A pressure-sensitive adhesive composition obtained by mixing 100 parts by mass of an acrylic random copolymer (A-1), 16 parts by mass of an acrylic triblock copolymer (B-1) and 43 parts by mass of a tackifying resin The solution was prepared by diluting with an ethyl / toluene (mass ratio 35/22) mixed solvent so that the total solid content was 25% by mass. The appearance of the obtained solution was transparent, and it did not become turbid or separated into two layers.

(2) To the pressure-sensitive adhesive solution obtained in (1) above, a cross-linking agent (trade name: L-45, isocyanate-based cross-linking agent, solid content 45%, manufactured by Soken Chemical Co., Ltd.) was added to prepare a pressure-sensitive adhesive. This was coated on a polyethylene terephthalate (PET) release film (Purex A43 made by Teijin DuPont Film, thickness of 50 μm) using a bar coater, and then dried at 90 ° C. for 3 minutes to obtain an adhesive layer / polyethylene terephthalate. An adhesive film made of a release film was produced. The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive film was as shown in Table 2 below. Moreover, the adhesive layer of the obtained adhesive film was transparent. After drying, a polyethylene terephthalate (PET) release film (Purex A50 manufactured by Teijin DuPont Film, thickness 50 μm) was bonded to prepare a film-like pressure-sensitive adhesive sheet, which was subjected to an aging treatment for 7 days in an environment of 23 ° C. and 50% RH. .

(3) About the film-like adhesive sheet obtained by said (2), the curved surface adhesiveness to a vinyl chloride resin board was evaluated with the following method.

[Curved surface adhesion evaluation]
The film-like pressure-sensitive adhesive sheet obtained above was cut into a size of 20 mm wide × 180 mm long, and the 0.4 mm thick aluminum plate was cut into the same size on the exposed first pressure-sensitive adhesive surface by peeling off the first release film. A test piece was prepared by pasting and backing. This test piece was bonded to a vinyl chloride resin plate having a thickness of 2 mm that had been cut into a size of 30 mm width × 200 mm length using a laminator in an environment of 23 ° C. and 50% RH, and then for 24 hours in the same environment. Retained. The vinyl chloride resin plate to which the test piece was attached was bent in an arc shape with a chord length of 190 mm. This was held for 96 hours in an atmosphere of 70 ° C., and the distance at which the end of the test piece was lifted from the surface of the vinyl chloride resin plate was measured. The results are shown in Table 2.

<< Examples 2-5, Comparative Examples 1-6 >>
A film-like pressure-sensitive adhesive as in Example 1 except that the composition of the acrylic random copolymer (A-1) and the block copolymers (B-1) to (B-4) is as shown in Table 2. Were prepared and evaluated. The results are shown in Table 2.

表２の結果より、本願発明の規定を満たす粘着剤組成物を用いた実施例１〜４の粘着剤は、優れた曲面接着性を示し、本願発明の規定を満たさない粘着剤組成物を用いた比較例１〜３の粘着剤は、曲面接着性に劣るものであった。

From the results of Table 2, the pressure-sensitive adhesives of Examples 1 to 4 using the pressure-sensitive adhesive composition satisfying the provisions of the present invention show excellent curved surface adhesiveness and use pressure-sensitive adhesive compositions that do not satisfy the provisions of the present invention. The pressure-sensitive adhesives of Comparative Examples 1 to 3 were inferior in curved surface adhesion.

  In the pressure-sensitive adhesive composition of the present invention, the compatibility and uniform dispersibility of each polymer component are good, so that not only the quality variation hardly occurs, but also the acrylic random copolymer and the acrylic homopolymer. Since the composition contains at least one polymer (A) and acrylic block copolymer (B) selected from a coalescence, when used as an adhesive, cohesive force, wetness to the adherend And an initial pressure-sensitive adhesive strength within an appropriate range for improving the curved-surface adhesive strength, and a highly reliable pressure-sensitive adhesive particularly useful for curved-surface bonding can be produced. Further, when the pressure-sensitive adhesive composition of the present invention is used as a solution-type pressure-sensitive adhesive, the solution viscosity is relatively low even when the solid content concentration is high. Furthermore, the pressure-sensitive adhesive composition of the present invention can also be used as a hot-melt pressure-sensitive adhesive. Therefore, the pressure-sensitive adhesive composition of the present invention is useful in various fields including the construction and building materials fields as pressure-sensitive processed products such as pressure-sensitive adhesive sheets used for curved molded products.

Claims (7)

  At least one polymer (A) selected from an acrylic random copolymer having an acrylic acid alkyl ester unit and an acrylic homopolymer, and at least one polymer block B1 mainly composed of a methacrylic acid alkyl ester unit and acrylic acid An acrylic block copolymer (B) having at least one polymer block B2 mainly comprising an alkyl ester unit and having at least one weight average molecular weight (Mw) of the polymer block B1 of 10,000 or more; An adhesive composition to contain.   The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic block copolymer (B) has a weight average molecular weight (Mw) of more than 120,000 and not more than 300,000.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the acrylic block copolymer (B) has a molecular weight distribution (Mw / Mn) of less than 1.5.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acrylic random copolymer (A) has a weight average molecular weight (Mw) of more than 300,000 and 3,000,000 or less.   The solvent-type adhesive formed by melt | dissolving or disperse | distributing the adhesive composition in any one of Claims 1-4 in the organic solvent.   The pressure-sensitive adhesive processed product having the pressure-sensitive adhesive composition layer according to claim 1.   The pressure-sensitive adhesive processed product according to claim 6, wherein the pressure-sensitive adhesive composition layer comprises a laminate formed between a base material layer and an adherend containing a vinyl chloride resin.