JPH11302617A - Hot melt pressure-sensitive adhesive and pressure-sensitive adhesive sheet and tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive having various excellent pressure-sensitive adhesive properties including high-temperature holding power by using a block copolymer having in the main chain a polymer block comprising an alkyl methacrylate and having a specified glass transition temperature and a polymer block comprising an alkyl(meth)acrylate and having a specified glass transition temperature. SOLUTION: This adhesive contains a block copolymer having in the main chain a structure represented by the formula:-[a1]-[b]-[a2]-(wherein [a1] and [a2] are each a polymer block based on an alkyl methacrylate, desirably, an ester of methacrylic acid with a 3C or lower alcohol, and having a glass transition temperature of +110 deg.C or above; and [b] is a polymer block based on an alkyl acrylate and/or an alkyl methacrylate, desirably, an ester of methacrylic acid with a 4C or higher alcohol and having a glass transition temperature of +30 deg.C or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hot-melt type pressure-sensitive adhesive which exhibits good adhesive properties in terms of holding power at high temperatures and the like, and is also excellent in heat resistance, weather resistance and hot-melt coating properties. "Adhesive" means "pressure-sensitive adhesive (p
less-sensitive adhesiv
e) "); manufactured using the hot melt type adhesive, exhibits good adhesive properties in terms of holding power at high temperatures, etc., and has excellent heat resistance, weather resistance and bleed resistance after application. The present invention relates to an excellent pressure-sensitive adhesive sheet or pressure-sensitive adhesive tape; and a polymer composition suitable as a material for the hot-melt pressure-sensitive adhesive.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive is used for producing a pressure-sensitive adhesive product 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). Hot-melt adhesives produced using this triblock copolymer have excellent adhesive properties at normal and low temperatures, and can be easily fluidized when heated and easily applied to substrates. Have. However, the hot melt pressure-sensitive adhesive using the triblock copolymer has a carbon-carbon double bond derived from a conjugated diene polymer block or an aromatic ring derived from an aromatic vinyl monomer polymer block in the molecule. Easily deteriorates due to ultraviolet light and heat.
It is not suitable for applications in which it is exposed to high temperature or ultraviolet irradiation after use, and therefore, there are great restrictions on 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 hot-melt type pressure-sensitive adhesive manufactured using the coalescence has good properties in terms of weather resistance and workability,
Since the cohesive force at a high temperature is still insufficient, it is desired to improve the adhesive property at a high temperature represented by a holding force at a high temperature.

An object of the present invention is to provide a hot-melt pressure-sensitive adhesive which is excellent in various adhesive properties such as holding power at high temperatures, has good heat resistance and weather resistance, and also has excellent hot-melt coating properties. An object of the present invention is to provide a pressure-sensitive adhesive sheet and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having these features, and a polymer material suitable as the pressure-sensitive adhesive.

[0008]

Means for Solving the Problems As a result of intensive studies by the present inventors, when a specific acrylic block copolymer is used as a base polymer of a pressure-sensitive adhesive, a hot-melt type pressure-sensitive adhesive suitable for the above purpose is used. The present invention was completed by finding that an adhesive, an adhesive sheet and an adhesive tape were obtained.

The present invention firstly comprises the following general formula:

[0010]

## STR3 ##-[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 hot-melt pressure-sensitive adhesive comprising a block copolymer (A) having a structure represented by the following formula in the polymer main chain:

[0013] The present invention is, secondly, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the above-mentioned hot-melt pressure-sensitive adhesive on at least a part of the surface of a substrate sheet.

The present invention is, thirdly, an adhesive tape having an adhesive layer comprising the above-mentioned hot-melt type adhesive on at least a part of the surface of the base tape.

Fourth, the present invention mainly comprises the above block copolymer (A) and a tackifier resin (B), and the content of the tackifier resin (B) is the same as that of the block copolymer (A). The polymer composition has a content of 5 to 500 parts by weight based on 100 parts by weight.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The hot melt pressure-sensitive adhesive of the present invention comprises, as an essential constituent, a block copolymer (A) having a structure represented by the above general formula (I) in the polymer main chain.
It contains.

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 holding power of the hot-melt pressure-sensitive adhesive using the same at a high temperature becomes 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) of the present invention, a plurality of glass transition temperatures such as the glass transition temperature of the polymer block a and the glass transition temperature of the polymer block b are obtained. Is the same as the glass transition temperature of the curve obtained by DSC measurement of a polymer having the same chemical structure (monomer composition, stereoregularity, etc.) as the polymer block a, Alternatively, since the temperature is close to that, it can be easily determined. 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 as a polymer having the same chemical structure as the polymer block a.

The syndiotacticity of the polymer block a is 70% or more. The syndiotacticity is 70
%, The resulting hot-melt pressure-sensitive adhesive has insufficient cohesive strength at high temperatures, and has 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 in deuterated chloroform. ) Content.

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. Other constituent components may be contained in the polymer block b 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 resulting hot-melt pressure-sensitive adhesive has poor adhesion, holding power, and the like.

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 can be obtained based on the curve obtained by the DSC measurement of the block copolymer (A) of the present invention, and the glass transition temperature derived from the polymer block b therein is as follows. 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 the same chemical structure as that of the polymer block b 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 b, 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.

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. In the block copolymer (A), if the proportion of the total weight of the polymer blocks a based on the total weight of the polymer blocks b contained in the molecule is too small, the obtained hot-melt pressure-sensitive adhesive is used. Cohesive force is reduced, holding power (shear creep strength)
On the other hand, if the proportion of the total weight of the polymer block a is too large, the resulting hot-melt pressure-sensitive adhesive tends to have insufficient tackiness. From these points, the polymer block a contained in the molecule of the block copolymer (A)
The ratio of the total weight of the polymer block b to the total weight of the polymer block b is a /
The weight ratio b is preferably in the range of 5/95 to 80/20, more preferably in the range of 10/90 to 75/25.

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 ), Or when the polymer main chain has an aromatic ring structure (for example, a paraxylylene group), the weather resistance of the hot melt adhesive 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.

Incidentally, 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, the block copolymer (A) is usually produced. However, it is not possible to form a polymer block a having a syndiotacticity of 70% or more.

The hot melt type pressure-sensitive adhesive of the present invention contains the above-mentioned block copolymer (A) as an essential component. Therefore, the hot melt-type pressure-sensitive adhesive of the present invention may be composed of only the block copolymer (A), but also includes those composed of a polymer composition further containing other components. Components that may optionally be included include tackifying resins, plasticizers, and other polymers.

In the hot melt type pressure-sensitive adhesive of the present invention, by adding a tackifying resin, the three components of the pressure-sensitive adhesive, ie, tack, adhesion and holding power, can be adjusted in a well-balanced manner. Therefore, it is generally preferred to incorporate a tackifier resin. Rosin-based resins such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester and maleated rosin; terpene phenol resins, α-pinene, β
Terpene resins based on pinene, limonene, etc .;
(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 amount of the tackifying resin can be appropriately selected according to the type of the tackifying resin, the use of the hot-melt type pressure-sensitive adhesive, the type of the adherend, and the like. Generally, 100 parts by weight of the block copolymer (A) is used. It is preferable to mix at a ratio of 5 to 500 parts by weight based on the weight of the mixture. Therefore, it mainly contains the block copolymer (A) and the tackifier resin (B), and the content of the tackifier resin (B) is based on 100 parts by weight of the sum of the content of the block copolymer (A). Polymer composition in the range of 5 to 500 parts by weight,
This is an embodiment suitable as a material for the hot melt pressure-sensitive adhesive of the present invention.

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, and fatty acid esters such as azelaic esters such as bis 2-ethylhexyl azelate; chlorinated paraffin and the like. 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 used is usually not more than 200 parts by weight per 100 parts by weight of the block copolymer (A).

The hot-melt pressure-sensitive adhesive of the present invention may further contain another polymer as long as the effects of the present invention are not impaired. Examples of such another polymer include poly n -Butyl acrylate, EPR, EPDM,
Examples thereof include an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, and polyvinyl acetate.

The hot-melt pressure-sensitive adhesive of the present invention comprises
Various additives may be contained as needed. Examples of such additives include antioxidants and ultraviolet absorbers for further improving weather resistance, heat resistance, and oxidation resistance;
Examples include inorganic powder fillers such as calcium carbonate, titanium oxide, mica, and talc; and fibrous fillers such as glass fibers and organic reinforcing fibers.

When the hot-melt pressure-sensitive adhesive of the present invention is a polymer composition of the block copolymer (A) and other components, the polymer composition is prepared by mixing a predetermined amount of a predetermined component. Can be prepared. The mixing method is not particularly limited. For example, the block copolymer (A) and the optional additive component are usually mixed in a known mixing or kneading apparatus such as a kneader-ruder, an extruder, a mixing roll, and a Banbury mixer. By mixing at a temperature in the range of from ° C to 250 ° C, a hot-melt pressure-sensitive adhesive can be prepared.

The hot-melt type pressure-sensitive adhesive of the present invention is applied by a hot-melt method, utilizing the property of easily melting under heating to have fluidity. Hot melt type adhesive in the molten state is in the form of a film, sheet, tape or other desired shape, paper, paper board,
An article having a pressure-sensitive adhesive layer on at least a part of the surface of a substrate can be manufactured by coating and cooling a substrate such as cellophane, an organic polymer film sheet, cloth, wood, or metal.

The articles obtained by forming the pressure-sensitive adhesive layer comprising the hot-melt pressure-sensitive adhesive of the present invention on a substrate as described above include pressure-sensitive adhesive sheets (including pressure-sensitive adhesive films), pressure-sensitive adhesive tapes, and pressure-sensitive adhesives. Tapes, masking tapes, electrical insulating tapes, laminates and the like can be mentioned.

Among the above-mentioned articles, a particularly typical example is that the pressure-sensitive adhesive layer comprising the hot-melt pressure-sensitive adhesive of the present invention comprises at least a part of a substrate sheet (including a substrate film) or a substrate tape. An adhesive sheet (including an adhesive film) or an adhesive tape on the surface can be used.

[0040]

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

REFERENCE EXAMPLE 1 500 ml of dry toluene and a bis (pentamethylcyclopentadienyl) samarium tetrahydrofuranate complex [(C ₅ Me ₅ ) as a polymerization initiator were placed in a 1000 ml flask whose inside was replaced with argon. ) 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).

REFERENCE EXAMPLE 2 In a 100 ml-volume flask whose inside was replaced with nitrogen, 20 ml of dry toluene 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. After the completion of the polymerization of MMA, 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 above-mentioned polymerization of LMA, 1.2 ml of MMA as a third monomer was added to the polymerization system for 10 minutes.
C. and the solution was stirred and reacted for 3 hours. The polymerization was stopped by adding 5 ml of methanol to the obtained reaction mixture and reacting at room temperature for 1 hour. 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).

Example 1 An adhesive tape was produced using the triblock copolymer obtained in Reference Example 1 as a hot-melt adhesive.
That is, this triblock copolymer is coated at a temperature of 220 ° C. using a coater on one side of a 100 μm-thick polyester film to a coating thickness of 40 μm, and the adhesive tape is cut by cutting the film into a predetermined width. Produced. The melt viscosity at 177 ° C. of the hot-melt pressure-sensitive adhesive comprising the triblock copolymer 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 for 100 seconds.
The value at c ^-1 shear rate was expressed in cps. Having an appropriate melt viscosity is a measure of good hot melt coatability.

Hot-melt coatability: Hot-melt adhesive was coated at a temperature of 220 ° C. with a coater to a thickness of 100 μm.
"Excellent" coating properties when coating to a coating thickness of 40 μm on polyester film
(◎), “good” (〇), “slightly poor” (△), “poor” (×), and “extremely poor” (xx).

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 attached to stainless steel having a thickness of 1 mm, and the peel 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” (（), “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: A piece of high-quality paper was adhered to an adhesive tape and heated at 70 ° C. for 2 weeks to check for exudation of the hot-melt type adhesive to the high-quality paper. The determination was made in two ranks of "good without exudation" (good) and "bad with exudation" (x).

Example 2 100 parts by weight of the triblock copolymer obtained in Reference Example 2 above was used as a hydrogenated aromatic copolymer-based tackifying resin ("Regalrez" manufactured by Hercules).
1078 ") and a hindered phenolic antioxidant (" Irganox 10 "manufactured by Ciba Geigy)
10 ") A polymer composition was obtained by mixing 1 part by weight at 220 ° C. for 20 minutes in a melting and mixing tank under melting conditions. Using this polymer composition as a hot-melt type pressure-sensitive adhesive, coating was carried out in the same manner as in Example 1 to prepare a pressure-sensitive adhesive tape. Various items were measured or evaluated in the same manner as in Example 1 with respect to the hot-melt pressure-sensitive adhesive made of this polymer composition. The results are shown in Table 1 below.

Comparative Example 1 A paraxylylene group was formed at the center of the molecular main chain by polymerizing nBA and MMA by an iniferter polymerization method using p-xylylene-bis (N, N-diethyldithiocarbamate) as a polymerization initiator. 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. Using this ABA as a hot-melt type pressure-sensitive adhesive, coating was performed in the same manner as in Example 1 to prepare a pressure-sensitive adhesive tape. With respect to the hot-melt adhesive composed of ABA, various items were measured or evaluated in the same manner as in 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") was used as a hot-melt type pressure-sensitive adhesive in the same manner as in Example 1 to prepare a pressure-sensitive adhesive tape. With respect to the hot-melt adhesive comprising HSIS, various items were measured or evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

[0057]

[Table 1]

From the results shown in Table 1, the hot-melt pressure-sensitive adhesives of Examples 1 and 2 according to the present invention all have hot-melt coating properties, various pressure-sensitive adhesive properties (particularly, holding power at high temperatures),
Excellent in heat resistance, weather resistance and bleeding resistance, whereas the hot melt pressure-sensitive adhesives of Comparative Examples 1 and 2 other than the present invention have high holding power at high temperatures,
It turns out that heat resistance and weather resistance are inferior. In addition, it can be seen that the hot-melt pressure-sensitive adhesive of Example 2 (in addition to the tackifier resin) according to the present invention is particularly excellent in hot-melt coating properties and various adhesive properties.

[0059]

The hot-melt pressure-sensitive adhesive of the present invention is melted by heating and becomes in a fluid state with good handleability, so that the hot-melt coating property on the base material is extremely good, and the pressure-sensitive adhesive tape, pressure-sensitive adhesive sheet, etc. Can be manufactured smoothly. Since the hot-melt type pressure-sensitive adhesive of the present invention is excellent in various pressure-sensitive adhesive properties (tack, holding power and pressure-sensitive adhesive strength), a high-quality pressure-sensitive adhesive article can be obtained by using it. Further, the hot-melt adhesive of the present invention,
It can exhibit high holding power under high temperature and has good heat resistance, weather resistance and bleed resistance, so even if it is placed in an environment exposed to heating atmosphere or ultraviolet rays for a long time after bonding, Strong adhesion can be maintained, and coloring,
There is no inconvenience such as excessive stickiness.

Claims (5)

[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.
A hot-melt pressure-sensitive adhesive comprising a block copolymer (A) having a structure represented by the following formula in the polymer main chain. 2. It mainly contains a block copolymer (A) and a tackifier resin (B), and the content of the tackifier resin (B) is 5 to 100 parts by weight of the content of the block copolymer (A). The hot-melt pressure-sensitive adhesive according to claim 1, comprising a polymer composition in an amount of from 500 to 500 parts by weight. 3. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the hot melt pressure-sensitive adhesive according to claim 1 on at least a part of the surface of a substrate sheet. 4. A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising the hot-melt pressure-sensitive adhesive according to claim 1 on at least a part of the surface of a base tape. 5. A compound represented by the following general formula:-[a1]-[b]-[a2]-(I) (wherein [a1] and [a2] are mainly alkyl methacrylates, respectively) 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.
The block copolymer (A) and the tackifier resin (B) having the structure represented by the following formula in the polymer main chain, and the content of the tackifier resin (B) is 1 in the block copolymer (A).
A polymer composition in the range of 5 to 500 parts by weight based on 00 parts by weight.