JPH11323072A - Block copolymer composition and its use as pressure-sensitive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for pressure sensitive adhesive or the like excellent in several adhesive properties such as high temperature tenacity and satisfactory in heat resistance and weatherability. SOLUTION: This composition consists of (A) a block copolymer which has a structure of the formula -[a1]-[b]-[a2]-, in the main chain, [a1] and [a2] are each a polymer block mainly consisting of an alkyl methacrylate which has a glass transition temperature of >=+110 deg.C and degree of syndiotacticity >=70%; [b] a polymer block mainly consisting of an alkyl (meth)acrylate which has a glass transition temperature of >=+30 deg.C}, and (B) a diblock copolymer at least including a polymer block mainly consisting of an alkyl (meth)acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in various adhesive properties (tack, holding power and adhesive strength) such as holding power at high temperature, and is excellent in heat resistance, weather resistance and hot melt coating property. Block copolymer composition, and a pressure-sensitive adhesive (pressure-sensitive adhesive; pressure-sensitive adhesive) in which the features of the block copolymer composition are effectively utilized.
eadhesive). Further, the present invention is produced using the block copolymer composition, and is excellent in various adhesive properties such as holding power at a high temperature, and has heat resistance after application, weather resistance and bleed resistance. Also relates to an excellent adhesive sheet or adhesive tape.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive is used for producing a pressure-sensitive adhesive article having a pressure-sensitive adhesive layer on at least a part of the surface of a substrate, such as a pressure-sensitive adhesive sheet or a pressure-sensitive adhesive tape. As a method of forming this adhesive layer, conventionally, an adhesive obtained by dissolving a base polymer such as natural rubber or synthetic rubber in an organic solvent is applied to a substrate,
A method comprising evaporating an organic solvent has been frequently used. Such an adhesive is called a solution-type adhesive based on its form. In recent years, environmental pollution prevention,
From the viewpoint of safety, resource saving, etc., instead of the solution type adhesive,
BACKGROUND ART A hot-melt type pressure-sensitive adhesive applied to a substrate in a molten state and an aqueous emulsion type pressure-sensitive adhesive applied to a substrate in an aqueous emulsion state have been widely used.

As a base polymer for a hot-melt type pressure-sensitive adhesive, a triblock copolymer consisting of an aromatic vinyl monomer polymer block, a conjugated diene polymer block and an aromatic vinyl monomer polymer block is known (US Pat. Patent No. 3,676,202, U.S. Patent No. 3,723,170). Adhesives produced using this triblock copolymer have excellent adhesive properties at room temperature and low temperature, and have features such as easy fluidization when heated and easy application to a substrate. I have. However, the pressure-sensitive adhesive using the triblock copolymer has a carbon-based bond derived from a conjugated diene polymer block.
Because it has a carbon-carbon double bond and an aromatic ring derived from an aromatic vinyl monomer polymer block in the molecule, it is easily degraded by ultraviolet light or heat, and is used in applications where it is exposed to high temperatures or ultraviolet radiation after use. Is not suitable, and therefore, there is a great limitation in use.

On the other hand, JP-B-59-33148, JP-A-9-125019, and JP-A-9-32441
No. 65, a block copolymer having a polymer block composed of an acrylic ester or a methacrylic ester and a polymer block composed of a vinyl monomer is proposed as a base polymer for an adhesive having excellent weather resistance. . These publications describe, as the block copolymer, a block copolymer having a polymer block composed of methyl methacrylate and a polymer block composed of an acrylate ester produced by utilizing a radical polymerization method. ing.

Japanese Patent Application Laid-Open No. 2-103277 discloses an iniferter weight using an iniferter such as xylylene-bis (N, N-diethyldithiocarbamate) or xylylene-bis (N-carbazolyldithiocarbamate). A block copolymer having a polymer block composed of a methacrylate ester and a polymer block composed of an acrylate ester is obtained by a synthetic method, and it has been proposed to use the block copolymer as a base polymer for an adhesive. .

[0006]

SUMMARY OF THE INVENTION A block copolymer having a polymer block composed of a methacrylate ester and a polymer block composed of an acrylate ester produced by using the above known radical polymerization method or iniferter polymerization method. The pressure-sensitive adhesive produced by using the coalesced material has good properties in terms of processability, and is a triblock copolymer composed of the above-mentioned aromatic vinyl monomer polymer block-conjugated diene polymer block-aromatic vinyl monomer polymer block. Although it has improved weather resistance compared to polymers, its cohesive strength at high temperatures is still insufficient, so it is desired to improve the adhesive properties at high temperatures represented by its holding power at high temperatures. .

An object of the present invention is to provide a pressure-sensitive adhesive (especially a hot-melt adhesive), which is excellent in various adhesive properties such as holding power at a high temperature, has good heat resistance and weather resistance, and is excellent in hot-melt coating property. A hot melt type pressure-sensitive adhesive), a pressure-sensitive adhesive having these characteristics, and a pressure-sensitive adhesive sheet and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having these characteristics.

[0008]

As a result of intensive studies by the present inventors, a polymer composition obtained by combining a specific acrylic block copolymer with another specific block copolymer has the above-mentioned features. The present invention has been completed by finding that a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet and a pressure-sensitive adhesive tape suitable for the above purpose can be obtained by using the same.

The present invention firstly comprises the following general formula:

[0010]

## STR2 ##-[a1]-[b]-[a2]-(I)

(Wherein [a1] and [a2] are polymer blocks each consisting mainly of an alkyl methacrylate, having a glass transition temperature of + 110 ° C. or more and a syndiotacticity of 70% or more. [B] represents a polymer block mainly composed of alkyl acrylate and / or alkyl methacrylate and having a glass transition temperature of + 30 ° C. or lower)

A block copolymer (A) having a structure represented by the following formula in the polymer main chain, and a polymer block mainly composed of alkyl acrylate and / or alkyl methacrylate as at least one polymer block. A block copolymer composition comprising a diblock copolymer (B).

The present invention secondly provides a pressure-sensitive adhesive comprising the above-mentioned block copolymer composition.

Thirdly, the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the above-mentioned block copolymer composition on at least a part of the surface of a substrate sheet.

Fourth, the present invention is an adhesive tape having an adhesive layer comprising the above block copolymer composition on at least a part of the surface of a base tape.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The block copolymer composition of the present invention comprises, as an essential component, a block copolymer (A) having a structure represented by the above general formula (I) in a polymer main chain, And a diblock copolymer (B) containing, as at least one polymer block, a polymer block mainly composed of an alkyl acrylate and / or an alkyl methacrylate.

In the above general formula (I), a polymer block represented by [a1] and a polymer block represented by [a2] (hereinafter, these polymer blocks may be collectively referred to as "polymer block a"). The main monomer component that constitutes (A) is an alkyl methacrylate. Alkyl methacrylate monomers that can constitute the polymer block a are not necessarily limited, 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,
One or more kinds such as 2-hexyldecyl methacrylate can be mentioned. However, the polymer block a
Need to make the glass transition temperature of + 110 ° C or higher,
It is generally preferable to mainly use an ester of methacrylic acid and an alcohol having 3 or less carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate. In the polymer block a, if the proportion is small, trimethylsilyl methacrylate;
Methacrylic esters other than alkyl esters such as trimethoxysilylpropyl methacrylate, glycidyl methacrylate, and allyl methacrylate; methyl acrylate,
Constituents derived from monomers such as alkyl acrylates such as n-butyl acrylate and t-butyl acrylate; olefins such as ethylene and propylene; lactones such as ε-caprolactone and valerolactone may be contained.

The glass transition temperature of the polymer block a is +1
10 ° C. or higher. When the glass transition temperature of the polymer block a is lower than + 110 ° C., the adhesive properties (particularly, the holding power at high temperatures) of the block copolymer composition using the same become insufficient.

In the present invention, the glass transition temperature of the polymer block a is observed in a curve obtained by measuring the block copolymer (A) with a differential scanning calorimeter (hereinafter, may be abbreviated as DSC). Extrapolation start temperature of the transition region of the polymer block a (Tgi; temperature of the intersection obtained by extrapolating the linear portion of the baseline before the transition and the tangent of the inflection point of the transition region;
For example, Yasutoshi Saito, "Basics of Thermal Analysis for Material Science"
(Published by Kyoritsu Publishing Co., Ltd. on December 15, 1990)
26 page). Based on the curve obtained by the DSC measurement of the block copolymer (A) in the present invention, a plurality of glass transition temperatures such as a glass transition temperature of the polymer block a and a glass transition temperature of the polymer block b are obtained. The glass transition temperature derived from the polymer block a of
Since the glass transition temperature of the polymer having the same chemical structure (monomer composition, stereoregularity, etc.) as the polymer block a is the same as or close to the glass transition temperature of the curve measured by DSC, it can be easily determined. Can be. The polymer having the same chemical structure as that of the polymer block a can be obtained by analyzing the block copolymer (A) by means of ¹ H-NMR, ¹³ C-NMR or the like to obtain a monomer composition of the polymer block a, Since the chemical structure such as stereoregularity is known, the compound can be easily produced by appropriate polymerization so that the chemical structure is reproduced. Further, when producing the block copolymer (A) of the present invention, if the first polymerization step is a step of forming the polymer block a, a part of the polymer block a formed in that step is left as it is. It is convenient to use a polymer having the same chemical structure as the polymer block a as a sample for DSC measurement.

The syndiotacticity of the polymer block a is 70% or more. The syndiotacticity is 70
%, The resulting block copolymer composition has insufficient cohesive strength at high temperatures, resulting in poor adhesive properties at high temperatures represented by holding power at high temperatures.
The syndiotacticity of the polymer block a is determined by ¹ H-NMR measurement and ¹³ C-NMR measurement of a sample obtained by dissolving the block copolymer (A) in deuterated chloroform. It is defined as the content of triad (rr).

In the above general formula (I), the main monomer components constituting the polymer block represented by [b] (hereinafter sometimes referred to as “polymer block b”) are alkyl acrylate and / or Or an alkyl methacrylate. The alkyl acrylate monomer that can constitute the polymer block b is not necessarily limited, but, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, One or more of isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, etc. may be mentioned. Can be. Examples of the alkyl methacrylate monomer that can constitute the polymer block b are not limited to, but include, for example, methyl methacrylate, ethyl methacrylate, and n-methacrylic acid.
Propyl, isopropyl methacrylate, n-methacrylate
-Butyl, isobutyl methacrylate, methacrylic acid se
c-butyl, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-methyl methacrylate One or more kinds such as hexyldecyl can be mentioned. However, when the polymer block b is constituted by using alkyl methacrylate as a main monomer component, the alkyl methacrylate monomer to be used is required to have a glass transition temperature of + 30 ° C. or lower. -Butyl, isobutyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-methacrylic acid 2-
It is preferable to mainly use an ester of methacrylic acid and an alcohol having 4 or more carbon atoms, such as ethylhexyl, pentadecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, and 2-hexyldecyl methacrylate. The polymer block b may contain other constituent components in a small proportion.

The glass transition temperature of the polymer block b is +3.
0 ° C. or less. When the glass transition temperature of the polymer block b is higher than + 30 ° C., the obtained block copolymer composition has adhesive properties (particularly adhesive strength, holding power, etc.).
Inferior to

The glass transition temperature of the polymer block b in the present invention is determined by the extrapolation start temperature (Tgi) of the transition region of the polymer block b observed in the curve obtained by measuring the block copolymer (A) by DSC. It is. As described above, a plurality of glass transition temperatures are obtained based on the curve obtained by the DSC measurement of the block copolymer (A) in the present invention, and the glass transition temperature derived from the polymer block b therein is Since the glass transition temperature of the polymer having the same chemical structure (monomer composition, stereoregularity, etc.) as that of b is the same as or close to the glass transition temperature of the curve measured by DSC, it can be easily determined. The polymer having a chemical structure similar to that of the polymer block b is obtained by converting the block copolymer (A) into ¹ H-NMR and ¹³ C-N
The chemical structure such as the monomer composition and stereoregularity of the polymer block b can be determined by analyzing by means such as MR, so that the polymer block b can be easily manufactured by appropriate polymerization so that the chemical structure is reproduced. Can be.

In the main chain of the block copolymer (A), as shown by the general formula (I), one polymer block b is located between two polymer blocks a. However, as long as the above three polymer blocks are included in a predetermined order, the polymer block may be composed of only these three polymer blocks, and may further include one or more other polymer blocks. It may be composed of four or more polymer blocks including blocks. The other polymer block may be the same type of polymer block as the polymer block a or b, or may be a different type of polymer block c. Another type of polymer block c includes olefins such as ethylene and propylene;
-Polymer blocks composed of lactones such as caprolactone and valerolactone.

In the present invention, the preferred form of the block copolymer (A) includes polymer block a-polymer block b-polymer block a, polymer block a-polymer block b-polymer block a-polymer. United block b, polymer block a-polymer block b-polymer block a
-A polymer block c.

The block copolymer (A) preferably has a total number average molecular weight in the range of 10,000 to 1,000,000, and in the range of 15,000 to 700,000. Is more preferred. Further, the molecular weight distribution of the entire block copolymer (A) is preferably in the range of 1.00 to 2.00 in the ratio of weight average molecular weight / number average molecular weight, and is preferably in the range of 1.00 to 1.50. More preferably, it is within the range.

In the block copolymer (A), if the proportion of the total weight of the polymer block a based on the total weight of the polymer blocks b contained in the molecule is too small, the obtained block copolymer is The cohesive force of the polymer composition tends to be small, and the adhesive properties such as the holding force (shear creep strength) tend to decrease. Conversely, if the proportion of the total weight of the polymer block a is too large, the resulting block copolymer weight The coalescence tends to be insufficient in adhesive properties (particularly adhesive strength). From these points, the ratio of the total weight of the polymer block a to the total weight of the polymer block b contained in the molecule of the block copolymer (A) is 5/95 to 8 in the weight ratio of a / b.
It is preferably within a range of 0/20 to 10 / 90-7.
More preferably, it is within the range of 5/25.

The block copolymer (A) used in the present invention
Has a functional group such as a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, or a trimethoxysilyl group in the molecular side chain or at the molecular main chain terminal, if necessary, as long as the effects of the present invention are not impaired. It may be. However, it is preferable that the block copolymer (A) has substantially neither a sulfur atom nor an aromatic ring in the molecule. When the block copolymer (A) has a sulfur atom at the terminal of the polymer main chain (for example, a group represented by the formula -SC (= S) -N (alkyl) ₂ is ), And when the polymer main chain has an aromatic ring structure (for example, para-xylylene group), the weather resistance of the block copolymer composition tends to decrease.

The block copolymer (A) used in the present invention
The production method is not particularly limited as long as a block copolymer satisfying the above-defined conditions for the chemical structure, glass transition temperature, syndiotacticity, etc. is obtained,
For example, using a suitable polymerization initiator, in an inert solvent, polymerizing a monomer mainly composed of alkyl methacrylate for forming polymer block a and alkyl acrylate for forming polymer block b The block copolymer (A) can be produced by a method comprising sequentially performing polymerization of a monomer mainly composed of an alkyl methacrylate and / or a desired block bonding order. Examples of the polymerization initiator in that case include organometallic compounds, among which,
An organic rare earth metal complex or an organic lithium compound is preferable in that the syndiotacticity of the formed polymer block a is easily increased to 70% or more. Organic rare earth metal complexes include rare earth metal complexes having a pentamethylcyclopentadienyl group as a ligand, for example, bis (pentamethylcyclopentadienyl) samarium methyltetrahydrofuranate, bis (pentamethylcyclopentadienyl) yttrium methyl And tetrahydrofuranate. Further, together with the organic rare earth metal complex, an alkyl aluminum such as trimethyl aluminum may be used as necessary. Examples of the organic lithium compound include alkyl lithium such as t-butyl lithium, and a compound obtained by reacting an alkyl lithium with 1,1-diphenylethylene, diphenylmethane, and the like. When an organic lithium compound is used as a polymerization initiator, an inorganic salt such as lithium chloride, a lithium salt of an alkoxide such as lithium 2- (2-methoxyethoxy) ethoxide, or diisobutyl (2,6-di-t-butyl-) is used. It is preferable that an additive such as an organic aluminum compound such as 4-methylphenoxy) aluminum coexist. Examples of the inert solvent for the polymerization include hydrocarbon solvents such as benzene, toluene, and xylene; halogenated hydrocarbon solvents such as chloroform, methylene chloride, and carbon tetrachloride; tetrahydrofuran;
An ether solvent such as diethyl ether can be used.

The case where the block copolymer (A) is produced by using an organic rare earth metal complex or an organic lithium compound as a polymerization initiator will be described. For example, a polymer block a is formed in the presence of the polymerization initiator. First stage polymerization step of polymerizing a monomer mainly composed of an alkyl methacrylate for polymerizing, a polymer block b
A second stage polymerization step of polymerizing a monomer mainly composed of an alkyl acrylate and / or an alkyl methacrylate for forming a polymer and a monomer mainly composed of an alkyl methacrylate for forming a polymer block a Can be produced through three or more polymerization steps including a third polymerization step for performing the polymerization. In the first stage polymerization step, a living polymer comprising a polymer block a having an active anion terminal at one end of the main chain is produced, and in the second stage polymerization step, an active anion terminal is formed at one end of the main chain of the polymer block b. A living polymer of a diblock of a polymer block a-polymer block b having a polymer block a is formed, and a polymer having an active anion terminal at one end of the main chain of one polymer block a in a subsequent third stage polymerization step Since a living polymer of a tertiary block of block a-polymer block b-polymer block a is formed, if the polymerization is terminated by reacting it with alcohol or the like, polymer block a-polymer block b-polymer block The ternary block copolymer (a) can be obtained. Here, if it is desired to produce a quaternary or higher block copolymer, the above polymer block a-polymer block b
A polymerization of a monomer mainly composed of alkyl acrylate and / or alkyl methacrylate for forming a polymer block b with respect to the living polymer of the tertiary block of the polymer block a; The desired number of polymerization operations such as polymerization of a monomer mainly composed of alkyl methacrylate to form a polymer, and polymerization of a desired monomer to form another polymer block c are performed in an appropriate number of times and sequentially.
Then, it may be subjected to a polymerization termination reaction with an alcohol or the like.

It should be noted that, even if an attempt is made to produce the block copolymer (A) by a known radical polymerization method or an iniferter polymerization method using an iniferter such as xylylene-bis (N, N-diethyldithiocarbamate), usually, However, it is not possible to form a polymer block a having a syndiotacticity of 70% or more.

In the block copolymer composition of the present invention, the above-mentioned block copolymer (A) and a polymer block mainly composed of an alkyl acrylate and / or an alkyl methacrylate are used as at least one polymer block. Containing diblock copolymer (B)
By combining the block copolymer (A) and the block copolymer (A) alone, it is possible to adjust the tack, the adhesive strength and the holding power, which are the three components of the adhesive, in a well-balanced manner, thereby improving the overall performance of the adhesive properties. And hot melt coatability is also improved.

In the above diblock copolymer (B), the main monomer constituting one of the polymer blocks (a) is an alkyl acrylate and / or an alkyl methacrylate. The alkyl acrylate monomer that can constitute the polymer block (a) is not necessarily limited, and examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-acrylate.
-Butyl, isobutyl acrylate, acrylic acid sec-
Butyl, t-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, etc.
Species or two or more species can be mentioned. Examples of the alkyl methacrylate monomer that can constitute the polymer block (a) are not limited to, but include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and methacrylic acid. n-butyl, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate,
One or more of n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyldecyl methacrylate, and the like can be given. In the polymer block (a), if the proportion is small, olefins such as ethylene and propylene; lactones such as ε-caprolactone and valerolactone; and diacrylates such as allyl methacrylate, vinyl methacrylate, allyl acrylate and vinyl acrylate. A component derived from a monomer such as a functional monomer may be contained.

The other polymer block (b) in the diblock copolymer (B) is not necessarily limited as long as it is a polymer block having a structure different from that of the polymer block (a) to be combined therewith. Examples of the monomer constituting are: aromatic vinyl monomers; conjugated dienes such as butadiene and isoprene; vinyl acetate; acrylonitrile; alkyl methacrylate; alkyl acrylate; olefins such as ethylene, propylene and isobutylene; ε-caprolactone; Lactones such as valerolactone and the like can be mentioned. Therefore, the polymer block (b) includes a polymer block mainly composed of alkyl acrylate and / or alkyl methacrylate (however, a polymer block having a structure different from that of the polymer block (a) combined therewith). Is done. When the polymer block (b) is mainly composed of monomers such as aromatic vinyl monomers, isoprene, butadiene, and isobutylene, various polyethylenes in the obtained block copolymer composition, It is effective for improving the adhesive properties to non-polar polymers such as polypropylene and polystyrene. Examples of the aromatic vinyl monomer include, but are not limited to, styrene, α-
Methylstyrene, p-methylstyrene, t-butylstyrene and the like can be exemplified. Incidentally, the polymer block (b) may have a bifunctional monomer such as allyl methacrylate, vinyl methacrylate, allyl acrylate, vinyl acrylate and the like, if the proportion is small.

The number average molecular weight of the diblock copolymer (B) is preferably in the range of 5,000 to 500,000, more preferably in the range of 6,000 to 400,000. . In addition, in the diblock copolymer (B), if the proportion of the polymer block (a) is too small, the compatibility with the block copolymer (A) is reduced. When used as an agent, bleeding tends to occur. Conversely, if the proportion of the polymer block (b) is too small, the adhesive properties of the block copolymer composition (particularly, adhesive strength at low temperatures) tend to decrease. is there. From these points, it is preferable that the weight ratio of the polymer block (a) to the polymer block (b) is in the range of 5/95 to 80/20 in the ratio of (a) / (b).
More preferably, it is in the range of 0/90 to 75/25.

The diblock copolymer (B) used in the present invention may have, if necessary, a hydroxyl group in a molecular side chain or a terminal of a molecular main chain, as long as the effects of the present invention are not impaired.
It may have a functional group such as a carboxyl group, an acid anhydride group, an amino group, and a trimethoxysilyl group. However, when it is desired to particularly enhance the weather resistance of the block copolymer composition, it is substantially free of an aromatic ring structure (for example, a paraphenylene group) in the molecular main chain and substantially contains a sulfur atom at the terminal of the main chain. It is preferable to use a diblock copolymer which does not have any specific properties.

The method for producing the diblock copolymer (B) is not particularly limited, and an anionic polymerization method, a cationic polymerization method, a polymerization method using an organic rare earth metal complex, a radical polymerization method, or the like is employed. can do. For example, in a polymerization method using an organic rare earth metal complex or an organic lithium compound as a polymerization initiator, diblock is carried out by a two-stage polymerization step in the same manner as the method exemplified above for the block copolymer (A). A copolymer can be produced.

In the block copolymer composition of the present invention, from the viewpoint that various adhesive properties (combined performance of tack, holding power and adhesive strength, etc.) and hot melt coatability are particularly good, the block copolymer composition is excellent. The weight ratio (A) / (B) of (A) and diblock copolymer (B) is from 20/80 to 95 /
5, preferably in the range of 25/75 to 90/1.
It is particularly preferred that it is in the range of 0.

The block copolymer composition of the present invention may be composed of only the above-mentioned block copolymer (A) and diblock copolymer (B), but may contain other components as required. May be. For example, when the block copolymer composition of the present invention is used as a pressure-sensitive adhesive or a pressure-sensitive adhesive layer forming material for a pressure-sensitive adhesive article, the components that may be arbitrarily compounded include tackifying resins, plasticizers, and other components. Polymers and the like can be mentioned.

In the block copolymer composition of the present invention, when a tackifier resin is added, the tack, the adhesive strength and the holding power may be easily adjusted. As the tackifying resin, rosin ester, gum rosin, tall oil rosin,
Rosin-based resins such as hydrogenated rosin ester and maleated rosin; terpene resins mainly composed of terpene phenolic resin, α-pinene, β-pinene, limonene; (hydrogenated)
One or more of petroleum resins, cumarone-indene resins, hydrogenated aromatic copolymers, styrene resins, phenolic resins, xylene resins and the like can be used. The compounding amount of the tackifier resin can be appropriately selected according to the type of the tackifier resin, the use of the adhesive, the type of the adherend, and the like, but the block copolymer (A) and the diblock copolymer ( In general, the proportion is not more than 500 parts by weight based on 100 parts by weight of the total of B).

Specific 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, bis 2-ethylhexyl adipate, di n -Adipates such as octyl adipate, sebacates such as bis 2-ethylhexyl sebacate, di-n-butyl sebacate, fatty acid esters such as azelaic esters such as bis 2-ethylhexyl azelate; chlorinated paraffins Glycols such as polypropylene glycol; epoxy polymer plasticizers such as epoxidized soybean oil and epoxidized linseed oil; phosphates such as trioctyl phosphate and triphenyl phosphate;
Phosphites such as triphenyl phosphite; ester oligomers such as an esterified product of adipic acid and 1,3-butylene glycol; polybutene; polyisobutylene; polyisoprene; process oil; These are used alone or in a mixture. The amount of the plasticizer to be used is usually 100 total of the block copolymer (A) and the diblock copolymer (B).
The ratio is 200 parts by weight or less per part by weight.

The block copolymer composition of the present invention may further contain other polymers as long as the effects of the present invention are not impaired. Examples of such other polymers include polyolefins. n-butyl acrylate, EPR, EPD
M, ethylene-ethyl acrylate copolymer, ethylene-
Examples thereof include a vinyl acetate copolymer and polyvinyl acetate.

The block copolymer composition of the present invention may contain various additives as necessary.
Examples of such additives include antioxidants and ultraviolet absorbers for further improving weather resistance, heat resistance, and oxidation resistance; inorganic powder fillers such as calcium carbonate, titanium oxide, mica, and talc; glass. Fibrous fillers such as fibers and fibers for organic reinforcement.

The block copolymer composition of the present invention is prepared by mixing the block copolymer (A), the diblock copolymer (B) and other components used as desired at a predetermined ratio. Can be prepared. The mixing method is not particularly limited. For example, each component is usually mixed at a temperature of 100 ° C. by using a known mixing or kneading apparatus such as a kneader ruder, an extruder, a mixing roll, and a Banbury mixer.
The block copolymer composition can be prepared by mixing at a temperature within the range of ２５０250 ° C.

The block copolymer composition of the present invention is suitable for use as a pressure-sensitive adhesive because it is excellent in various adhesive properties such as holding power at high temperatures, and also excellent in heat resistance and weather resistance. . Furthermore, since the block copolymer composition of the present invention usually easily melts under heating and becomes fluid, it is particularly suitably used as a hot-melt adhesive.

In the molten state, the block copolymer composition of the present invention may be in the form of a film, sheet, tape, or other desired shape, paper, paper board, cellophane, organic polymer film sheet, cloth, By coating and cooling a substrate such as wood or metal, an adhesive article having an adhesive layer comprising the block copolymer composition on at least a part of the surface of the substrate can be produced. Further, the block copolymer composition of the present invention can be used as a solvent-type pressure-sensitive adhesive in a solution by dissolving in a solvent such as toluene. May be manufactured.

The pressure-sensitive adhesive articles obtained by forming the pressure-sensitive adhesive layer comprising the block copolymer composition of the present invention on a substrate as described above include pressure-sensitive adhesive sheets (including pressure-sensitive adhesive films), pressure-sensitive adhesive tapes, Examples include a pressure-sensitive tape, a masking tape, an electrical insulating tape, and a laminate.

Among the above-mentioned pressure-sensitive adhesive articles, a particularly typical example is that the pressure-sensitive adhesive layer comprising the block copolymer composition of the present invention comprises at least one of a base sheet (including a base film) or a base tape. Examples thereof include an adhesive sheet (including an adhesive film) or an adhesive tape on the surface of the part.

[0049]

EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited thereto.

Synthesis Example 1 500 ml of dry toluene and a bis (pentamethylcyclopentadienyl) samarium tetrahydrofuranate complex [(C ₅ Me ₅₎ ) ₂ Sm
[Me (THF)] 1002 g of dry toluene solution 100
ml was added. To this, at 0 ° C., methyl methacrylate (M
MA) was added and stirred at 0 ° C. for 30 minutes.
20 ml of the solution was sampled from the system (sample 1). After the above MMA polymerization, the polymerization reaction system is
After cooling to 78 ° C., 66.6 ml of n-butyl acrylate (nBA) as a second monomer was added, and
For 3 hours. 20 ml of the solution was sampled from the system (sampling sample 2). After the above nBA polymerization, MMA was added to the polymerization system as a third monomer.
16.0 ml were added at -78 ° C and the solution was stirred. After the solution became homogeneous, the temperature was raised to 0 ° C., and the mixture was further stirred for 1 hour. 50 ml of methanol was added to the obtained reaction mixture.
In addition, the polymerization was stopped by reacting at room temperature for 2 hours. The reaction solution after the termination of the polymerization was poured into a large amount of hexane to obtain a precipitated white precipitate. A part thereof was sampled (sample 3).

The polymers in the sampling samples 1 to 3 were subjected to NMR measurement, DSC measurement, and GPC (gel permeation chromatography) measurement, and based on the results, the number average molecular weight (Mn), PMMA / PnBA
(Polymethyl methacrylate block / polyacrylic acid n
-Butyl block) ratio and the like, the white precipitate was found to be polymethyl methacrylate (PMMA) block-
Triblock copolymer of n-butyl polyacrylate (PnBA) block-polymethyl methacrylate (PMMA) block (PMMA-b-PnBA-b-PMMA)
The syndiotacticity of the PMMA block is 83.6%, the glass transition temperature of the block is 122 ° C., the glass transition temperature of the PnBA block is −45 ° C., and the copolymer The overall Mn is 82700
Mw / Mn (molecular weight distribution) of the whole copolymer was 1.09, and the ratio of each polymer block was PMMA.
(16% by weight) -PnBA (69% by weight) -PMMA
(15% by weight).

Synthesis Example 2 500 ml of dry toluene and a bis (pentamethylcyclopentadienyl) samarium tetrahydrofuranate complex [(C ₅ Me ₅₎ ) ₂ Sm
[Me (THF)] 0.34 g of a dry toluene solution 100
ml was added. To this, at 0 ° C., methyl methacrylate (M
MA) was added and stirred at 0 ° C. for 30 minutes. 10 ml was sampled from the system (sample 1). After the above-mentioned polymerization of MMA, the polymerization reaction system was cooled to −78 ° C., 33.3 ml of n-butyl acrylate (nBA) was added as a second monomer, and the mixture was stirred at −78 ° C. for 3.5 hours. . The polymerization was terminated by adding 50 ml of methanol to the obtained reaction mixture and reacting at room temperature for 2 hours. The reaction solution after the termination of the polymerization was poured into a large amount of methanol to obtain a precipitate. A part thereof was sampled (sampling sample 2).

The polymers in the sampling samples 1 and 2 were subjected to NMR measurement, DSC measurement, and GPC measurement, and based on the results, the number average molecular weight (Mn), PM
When the ratio of MA / PnBA (polymethyl methacrylate block / poly (n-butyl acrylate) block) was determined, the precipitate was found to be polymethyl methacrylate (PMMA).
Diblock copolymer of block-n-butyl acrylate (PnBA) block (PMMA-b-PnBA)
The syndiotacticity of the PMMA block is 82.8%, the PnBA block is atactic, the Mn of the entire copolymer is 73,700,
Mw / Mn of the whole copolymer was 1.04, and the ratio of each polymer block was PMMA (13% by weight) -PnBA.
(87% by weight).

Synthesis Example 3 20 ml of dry toluene was placed in a 100-ml flask whose inside was replaced with nitrogen, and t-
0.31 ml of a pentane solution containing 1.57 mol / l of butyllithium was added, and 1.3 ml of triisobutylaluminum and 2,6-di-t-butyl- were added thereto.
10 ml of a toluene solution of an organoaluminum compound prepared from 1.1 g of 4-methylphenol was added. To this, methyl methacrylate (MMA) was added at −10 ° C. for 1.2 times.
Then, the mixture was stirred at -10 ° C for 1 hour. MMA above
After completion of the polymerization, 8.5 ml of lauryl methacrylate (LMA) was added as the second monomer, and the mixture was stirred at -10 ° C for 5 hours. After the completion of the above-mentioned polymerization of LMA, 1.2 ml of MMA was added to this polymerization system as a third monomer at −1
The solution was added at 0 ° C., stirred, and reacted for 3 hours. 5 ml of methanol was added to the obtained reaction mixture, and the mixture was added at room temperature for 1 hour.
The polymerization was stopped by reacting for hours. After terminating the polymerization in this manner, the obtained solution was poured into a large amount of methanol, and a polymer was quantitatively obtained as a precipitate.

Each polymer in the sample sampled on the way was subjected to NMR measurement, DSC measurement, and GPC measurement, and the number average molecular weight (Mn), PM
When the ratio of MA / PLMA (polymethyl methacrylate block / polylauryl methacrylate block) was determined, the precipitate was found to be polymethyl methacrylate (PMMA)
Block-polylauryl methacrylate (PLMA) block-polymethyl methacrylate (PMMA) block triblock copolymer (PMMA-b-PLMA-b-
PMMA), the syndiotacticity of the PMMA block portion is 73%, the glass transition temperature of the block portion is 114 ° C, the glass transition temperature of the PLMA block portion is -60 ° C, and the copolymer The overall Mn is 91
Mw / Mn of the entire copolymer was 1.23, and the polymer block ratio was PMMA (12% by weight).
-PLMA (75% by weight) -PMMA (13% by weight).

Reference Example 1 An adhesive tape was produced using the triblock copolymer obtained in Synthesis Example 1 as a hot-melt adhesive.
That is, 100 parts by weight of the triblock copolymer was mixed with 1 part by weight of a hindered phenolic antioxidant ("Irganox 1010" manufactured by Ciba Geigy) under melting conditions at 220 ° C. for 20 minutes in a melting and mixing tank. Then, at a temperature of 220 ° C., using a coater, the thickness is 100 μm.
Was coated on one side of a polyester film having a coating thickness of 40 μm, and the film was cut into a predetermined width to prepare an adhesive tape. For this triblock copolymer, the melt viscosity at 177 ° C. was measured by the following method. The coatability during the above coating was evaluated by the following method. Using the obtained adhesive tape, various adhesive properties [adhesiveness (ball tack), holding power and adhesive strength], heat resistance, weather resistance and bleed resistance were measured or evaluated by the following methods. The measurement results and evaluation results are shown in Table 1 below.

Melt viscosity: The melt viscosity was measured at 177 ° C. using a rheometric mechanical spectrometer 800 (with a parallel plate), and was measured at a shear rate of 1
The value at 00 sec ^-1 was expressed in cps units. Having an appropriate melt viscosity is a measure of good hot melt coatability.

Hot melt coatability: The coatability when coating the pressure-sensitive adhesive to a coat thickness of 40 μm on a polyester film having a thickness of 100 μm using a coater at a temperature of 220 ° C. is “very good” (」). ), "Good"
(〇), “Slightly poor” (△), “Defective” (×), and “Extremely poor” (XX) were determined in five ranks.

Adhesion (ball tack): JIS Z02
The ball tack values at 10 ° C. and 25 ° C. were examined according to 37. Here, the larger the ball tack value, the better the tackiness (tackiness).

Holding force: 25 mm × 25 mm of adhesive tape
A load of 1 kg was applied in the direction parallel to the bonding surface of the sample, left in an atmosphere at a temperature of 25 ° C., 80 ° C. or 160 ° C., and the time required for the load to drop was measured to evaluate the holding power. did. The longer the holding time, the better the holding power (creep performance). Further, a long holding time at 160 ° C. indicates that the holding power under a high temperature condition is excellent.

Adhesive force: An adhesive tape was adhered to stainless steel having a thickness of 1 mm, and the peeling force required when peeling at an angle of 180 degrees was measured.

Heat resistance: After the adhesive tape was left in the air at 180 ° C. for 12 hours, the coloring of the adhesive layer was visually observed, and the heat resistance was evaluated as “very good without any coloring” (認 め), “coloring”. Slightly a little ”(△),“ Coloring is extremely poor ”
(X) was determined in three ranks.

Weather resistance: Adhesive tape was used according to JIS A141
0 and subjected to a one-month outdoor exposure test. The coloring of the pressure-sensitive adhesive layer after the test was visually observed, and the weather resistance was evaluated as “very good without any coloring” (）), “slightly colored”.
(△), the evaluation was divided into three ranks of “significantly poor coloring” (×).

Bleed resistance: Adhesive tape was bonded to high-quality paper and heated at 70 ° C. for 2 weeks to check for exudation of the adhesive on the high-quality paper. The evaluation was made in two ranks: good (○), not good (○), and poor (bleeding was observed) (x).

Examples 1 to 3 The triblock copolymer obtained in Synthesis Example 1 and the diblock copolymer obtained in Synthesis Example 2 were premixed in the proportions shown in Table 1 below. 100 parts by weight were mixed with 1 part by weight of a hindered phenolic antioxidant ("Irganox 1010" manufactured by Ciba-Geigy Co., Ltd.) in a melting and mixing tank at 220 ° C. for 20 minutes under melting conditions to obtain a block copolymer. A combined composition was obtained. These block copolymer compositions were coated as in Reference Example 1 using a hot-melt pressure-sensitive adhesive to prepare a pressure-sensitive adhesive tape. That is, each of these block copolymer compositions is coated at a coating thickness of 40 μm on one side of a 100 μm thick polyester film using a coater at a temperature of 220 ° C., and the film is cut into a predetermined width. Thus, an adhesive tape was produced. With respect to these block copolymer compositions, various items were measured or evaluated in the same manner as in Reference Example 1. The results are shown in Table 1 below.

Example 4 100 parts by weight of the triblock copolymer obtained in Synthesis Example 3 and the diblock copolymer 30 obtained in Synthesis Example 2 were used.
Parts by weight, hydrogenated aromatic copolymer-based tackifying resin ("Regalrez" manufactured by Hercules)
1078 "), 10 parts by weight, and a hindered phenolic antioxidant (" Irganox 1 "manufactured by Ciba Geigy)
010 ") 1 part by weight was mixed in a melt mixing tank at 220 ° C. for 20 minutes under melting conditions to obtain a block copolymer composition. This block copolymer composition was used as a hot-melt type pressure-sensitive adhesive, and coated and cut in the same manner as in Reference Example 1 to produce a pressure-sensitive adhesive tape. With respect to this block copolymer composition, various items were measured or evaluated in the same manner as in Reference Example 1. The results are shown in Table 1 below.

COMPARATIVE EXAMPLE 1 nBA and MMA were polymerized by an iniferter polymerization method using p-xylylene-bis (N, N-diethyldithiocarbamate) as a polymerization initiator, whereby a para-xylylene group was formed at the center of the molecular main chain. a molecular backbone at both ends each formula -S-C (= S) -N (C 2 H 5) PMMA having a group represented by ₂ (14 parts by weight) -PnBA (72
(Weight part) -PMMA (14 weight part) triblock copolymer (this is abbreviated as "ABA") was obtained. That PM
The syndiotacticity of the MA block is 60%, and the number average molecular weight (Mn) of the entire triblock copolymer
Was 140000, and the molecular weight distribution (Mw / Mn) was 2.26. This ABA was used as a hot-melt adhesive, and ABA1 was used in the same manner as in Reference Example 1.
After melt-mixing with 1 part by weight of a hindered phenolic antioxidant with respect to 00 parts by weight, an adhesive tape was produced by coating and cutting. Regarding this ABA, various items were measured or evaluated in the same manner as in Reference Example 1. The results are shown in Table 1 below.

Comparative Example 2 Hydrogenated product of styrene-isoprene-styrene triblock copolymer (number average molecular weight: 110000; total styrene unit content: 30% by weight; 1,4-bond amount of polyisoprene portion before hydrogenation) : 89%; hydrogenation rate: 95%) (this is abbreviated as "HSIS") as a hot-melt type pressure-sensitive adhesive.
After melt-mixing with 1 part by weight of a hindered phenolic antioxidant with respect to 0 parts by weight, an adhesive tape was produced by coating and cutting. Regarding this HSIS, various items were measured or evaluated in the same manner as in Reference Example 1. The results are shown in Table 1 below.

[0069]

[Table 1]

From the results shown in Table 1 above, the block copolymer compositions of Examples 1 to 4 according to the present invention show various adhesive properties such as hot melt coatability and holding power at high temperature, heat resistance and weather resistance. It can be seen that they have good performance in all of the properties and the bleeding resistance. Furthermore, even in comparison with the triblock copolymer alone of Reference Example 1, it is excellent in tack, adhesive strength and hot melt coatability, and
It can be seen that they have almost the same high holding power. On the other hand, it can be seen that the block copolymers of Comparative Examples 1 and 2 other than the present invention are inferior in holding power at high temperatures, heat resistance and weather resistance, and are also slightly inferior in coatability.

[0071]

The block copolymer composition of the present invention is useful as a pressure-sensitive adhesive because it is excellent in various pressure-sensitive properties (tack, holding power and pressure-sensitive adhesive strength). A high quality adhesive article can be obtained. Moreover, since the block copolymer composition of the present invention is melted by heating and becomes in a fluid state with good handleability, it has a very good hot-melt coating property on a substrate and can be used as a hot-melt adhesive. Thereby, an adhesive article can be manufactured smoothly. Furthermore, pressure-sensitive adhesives and pressure-sensitive adhesive articles using the block copolymer composition of the present invention can exhibit high holding power at high temperatures, and have good heat resistance, weather resistance and bleed resistance, so that they can be used for a long time after bonding. Even when placed in a heating atmosphere or an environment exposed to ultraviolet rays, strong adherence between adherends can be maintained, and inconveniences such as coloring and excessive stickiness do not occur.

Claims (6)

[Claims] 1. The following general formula: ## STR1 ##-[a1]-[b]-[a2]-(I) (wherein [a1] and [a2] each consist mainly of an alkyl methacrylate ester. A polymer block having a glass transition temperature of + 110 ° C. or more and a syndiotacticity of 70% or more; [b]
Represents a polymer block mainly consisting of alkyl acrylate and / or alkyl methacrylate and having a glass transition temperature of + 30 ° C. or lower.
And a block copolymer (A) having a structure represented by the following formula in the polymer main chain, and a polymer containing at least one polymer block mainly composed of an alkyl acrylate and / or an alkyl methacrylate as a polymer block. A block copolymer composition comprising a block copolymer (B). 2. The weight ratio (A) / (B) of the block copolymer (A) to the diblock copolymer (B) is from 20/80.
The block copolymer composition according to claim 1, which is in the range of 95/5. 3. An adhesive comprising the block copolymer composition according to claim 1 or 2. 4. The pressure-sensitive adhesive according to claim 3, which is a hot-melt pressure-sensitive adhesive. 5. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the block copolymer composition according to claim 1 on at least a part of the surface of a substrate sheet. 6. An adhesive tape having an adhesive layer comprising the block copolymer composition according to claim 1 on at least a part of the surface of a base tape.