JPH11116644A - Block copolymer and its polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a block copolymer that can provide an adhesive with well balance between cohesion and adhesion and to provide, its polymerization method, and to obtain an adhesive composition containing the same and an adhesive product using the same. SOLUTION: This block copolymer is prepared by linking a (meth)acrylic alkyl ester polymer block A to another polymer block B that is incompatible with the polymer block A through a bridge of the general formula (X is a 3-10C alkylene group; R2 is a 1-5C alkyl group) where the difference (TgA-TgB) between the glass transition point of the polymer block A (TgA) and that of the polymer block B (TgB) is preferably >=15 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block copolymer capable of providing a pressure-sensitive adhesive having an improved balance between cohesive strength and adhesive strength, a method for polymerizing the block copolymer, and a resin composition for a pressure-sensitive adhesive containing the block copolymer. And an adhesive product using the same.

[0002]

[Prior art]

(Meth) acrylic pressure-sensitive adhesives containing (meth) acrylic acid alkyl ester-based polymer as a main component are superior in heat resistance, weather resistance, water resistance, oil resistance, transparency, etc., as compared with rubber-based adhesives. Therefore, in recent years, it has been widely used as an adhesive.

Here, in order to improve the physical properties of an adhesive, it is necessary to improve tackiness (adhesion caused by instantaneous contact), adhesive strength (peel adhesive strength), and cohesive strength (holding power). is there. However, tackiness and adhesive strength (hereinafter, collectively referred to as “adhesive strength” when not particularly distinguishing between them) and cohesive strength are opposite properties, and it is difficult to improve both in a well-balanced manner. . For example, when the cohesive force is improved by increasing the crosslink density or blending a polymer having a high glass transition temperature, there is a problem that the adhesive force is reduced as a reaction. On the other hand, in an attempt to increase the adhesive strength, the content of monomers having a low glass transition point such as butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate in the alkyl (meth) acrylate-based polymer is increased.
When a molecular design is made so as to lower the glass transition temperature of the polymer, cohesive failure tends to occur without being able to withstand deformation due to pressure, and cohesive force cannot be exerted.

In recent years, pressure-sensitive adhesives using polymer alloys such as graft copolymers and block copolymers have been proposed as pressure-sensitive adhesives which have both improved adhesion and cohesion while improving both. For example, as a resin composition for an adhesive using a graft copolymer,
JP-A-32438, JP-A-8-143847, and JP-A-8-209999 propose a resin composition for an adhesive produced by a radical copolymerization method using a macromonomer. Further, as a resin composition for an adhesive using a block copolymer, JP-B-59-3314.
No. 8, JP-A-2-103277, JP-A-5-103
JP-A-43857 proposes a pressure-sensitive adhesive composition having a block copolymer composed of polymer blocks having different glass transition points.

[0005]

In general, in order to increase the cohesive strength of a pressure-sensitive adhesive in a copolymer, it is necessary to increase the molecular weight of the tacky polymer portion (alkyl (meth) acrylate-based polymer portion). It is considered effective.

However, in the polymerization of the graft copolymer, the reactivity of the macromonomer decreases as the molecular weight of the macromonomer increases as the concentration of the terminal unsaturated double bond in the macromonomer decreases. A decrease in the reactivity of the macromonomer leads to a decrease in the yield of the graft copolymer, and eventually,
It becomes difficult to improve the properties as an adhesive. In addition, since macromonomers are expensive monomers, they are not economical as a raw material for an adhesive composition.

On the other hand, in the synthesis of a block copolymer, there is a method of synthesizing a polymer having a functional group at a terminal and then adding the polymer having the functional group to react the terminal groups with each other. However, there is a problem that the concentration of the functional group at the terminal becomes too low to allow a sufficient reaction.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive having a good balance between cohesion and adhesion by using a special initiator. An object of the present invention is to provide a block copolymer which can be produced, a polymerization method thereof, a resin composition for a pressure-sensitive adhesive containing the same, and a pressure-sensitive adhesive product using the same.

[0009]

That is, the block copolymer of the present invention comprises a (meth) acrylic acid alkyl ester-based polymer block A and a polymer block B having no compatibility with the polymer block A represented by the general formula:

[0010]

Embedded image (Wherein, X is a C ₃ -C ₁₀ alkylene group, R ₂ is a C ₁ -C ₁₀
It represents an alkyl group of C _5. ).

The difference (Tg _B -Tg _A ) between the glass transition temperature (Tg _A ) of the polymer block _A and the glass transition temperature (Tg _B ) of the polymer block B is preferably 15 ° C. or more.

It is preferable that the haze value (%) of the block copolymer of the present invention when immersed in methanol at room temperature for 1 hour is larger than the initial haze value (%) by 3 or more.

The polymerization method of the block copolymer of the present invention comprises a compound represented by a general formula

[0014]

Embedded image (Wherein X is a C ₃ -C ₁₀ alkylene group, R ₁ and R
₂ represents the same or different C ₁ -C ₅ alkyl groups. ) Is added to the polymer block B to which the peroxyester group is bonded, and a monomer constituting the (meth) acrylic acid alkyl ester-based polymer block A, which is incompatible with the polymer block B, is polymerized. Or the end is a general formula

[0015]

Embedded image (Wherein X is a C ₃ -C ₁₀ alkylene group, R ₁ and R
₂ represents the same or different C ₁ -C ₅ alkyl groups. ), A monomer constituting a polymer block B which is incompatible with the polymer block A is added to the (meth) acrylic acid alkyl ester-based polymer block A to which a peroxyester group is bonded. .

The pressure-sensitive adhesive resin composition of the present invention contains the block copolymer of the present invention. Or,
It contains the polymer obtained by the polymerization method of the present invention.

In such a resin composition for an adhesive,
Polymer block A constituting the block copolymer
The difference between the refractive index of the polymer block B is 0.0
By selecting so as to be 5 or less, it is possible to obtain a highly transparent resin composition for an adhesive, and conversely, the difference between the refractive index of the polymer block A and the refractive index of the polymer block B exceeds 0.05. By selecting such a composition, a resin composition for a pressure-sensitive adhesive having a high concealing property can be obtained.

The pressure-sensitive adhesive product of the present invention has a pressure-sensitive adhesive layer containing the resin composition for a pressure-sensitive adhesive of the present invention formed on one or both sides of a substrate.

[0019]

Embodiments of the present invention will be described below. In the following, when acrylic acid and methacrylic acid are not distinguished, they are abbreviated as (meth) acrylic acid.

First, the polymer block A and the polymer block B constituting the block copolymer of the present invention will be described.

The polymer block A is a (meth) acrylic acid alkyl ester-based polymer block, which is a polymer portion exhibiting mainly adhesive force in a block copolymer, and may be a homopolymer or a copolymer.

The monomer composition of the polymer block A is as follows:
It preferably contains 70% by weight or more, more preferably 80% by weight or more, of a (meth) acrylic acid alkyl ester-based monomer (hereinafter collectively referred to as "monomer a group").

Here, the group of monomers a is not particularly limited as long as the alkyl group has 1 to 12 carbon atoms. Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. Butyl, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate,
Dodecyl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned.

When the content ratio of the monomer a group in the polymer block A exceeds 99.9% by weight, the cohesive force is often insufficient, so that at least one selected from the following monomer b group should be contained. preferable. Examples of the monomer b group include carboxyl group-containing unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic anhydride, and maleic acid;
Amide group-containing unsaturated monomers such as acrylamide and N-methylol acrylamide; hydroxyl group-containing unsaturated monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; 2-hydroxy (meth) acrylate An unsaturated monomer having a reactive functional group such as a modified polycaprolactone of ethyl (trade name: Placcel F series (manufactured by Daicel Chemical Industries, Ltd.)) may be used. The monomer b group (unsaturated monomer having a reactive functional group) imparts a crosslinking point to the polymer block A, so that when a crosslinking agent described later coexists, it is possible to increase the molecular weight of the polymer block and improve the cohesive force. Can be done. Therefore, the monomer b in the polymer block A
The content ratio of the group is preferably 0.01% by weight or more, more preferably 0.1% by weight or more. On the other hand, the upper limit of the content ratio is preferably 10% by weight or less, more preferably 8% by weight.
% By weight or less. If the content ratio of the monomer b group exceeds 10% by weight, the cohesive strength becomes too high, and the adhesive strength and rebound resistance tend to decrease.

In the polymer block A, one selected from vinyl group-containing monomers other than those described above (hereinafter collectively referred to as “monomer c group”) as long as the above requirements are satisfied.
Species or two or more kinds may be contained as necessary. Examples of the monomer c group include aromatic unsaturated monomers such as styrene and α-methylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; N-vinylpyrrolidone;
And monomers such as nitrogen-containing unsaturated monomers such as acryloyl morpholine.

As long as the above-mentioned monomer is contained within a predetermined range, the combination can be appropriately selected according to the properties and application of the pressure-sensitive adhesive. A glass transition point (Tg
_A ) is −80 ° C. or more, preferably −70 ° C. or more,
It is preferable to combine them so as to be not more than 20 ° C, preferably not more than 20 ° C. Even if the glass transition temperature is −20 ° C. or higher, that is, even if there is no tack at room temperature, the adhesive layer can be developed by irradiating the adhesive layer with a far-infrared lamp. Further, the weight average molecular weight of the polymer block A is preferably 10 × 10 ⁴ or more, more preferably 20 × 10 ⁴ or more. If the weight average molecular weight of the polymer block A is less than 10 × 10 ⁴ , the cohesive strength will be insufficient.

The polymer block B is a polymer portion mainly exhibiting a cohesive force in the block copolymer.
Any homopolymer or random copolymer may be used as long as it is not compatible with the polymer block A.

The constituent monomer composition of the polymer block B includes the above-mentioned monomer group a (alkyl (meth) acrylate-based monomer), monomer group B for providing a crosslinking point (reactive functional group-containing monomer), and monomer c One or more selected from the group (other polymerizable vinyl group-containing monomers) on condition that they are not compatible with the polymer block A. In short, the polymer block B can be appropriately combined with the above-mentioned monomers as long as the polymer block B having no compatibility with the polymer block A can be obtained. However, in order to improve the balance between the adhesive force and the cohesive force, the difference (Tg _B -Tg the glass transition temperature of the polymer block B (Tg _B) glass transition temperature of the polymer blocks a and (Tg _a)
It is preferred that _A ) is selected to be at least 15 ° C, preferably at least 30 ° C, more preferably at least 60 ° C.

When it is desired to obtain a highly transparent resin composition for an adhesive, the difference between the refractive index of the polymer block A and the refractive index of the polymer block B is 0.05 or less, preferably 0.04 or less. And more preferably 0.03 or less. On the other hand, when it is desired to obtain a resin composition for a pressure-sensitive adhesive having a high concealing property, the difference may be selected so that the difference in refractive index is more than 0.05, preferably 0.1 or more. Further, the weight average molecular weight of the polymer block B is 2 × 10 ⁴
As described above, it is preferably 5 × 10 ⁴ or more. The weight average molecular weight of the polymer block B is 2 × 10 ⁴
If the amount is less than the above, the cohesive strength is insufficient.

Further, in the polymer block A or the polymer block B, within a range satisfying the above-mentioned predetermined requirements,
By appropriately selecting the monomer composition constituting the polymer block, it is possible to provide a block copolymer according to the properties and use of the pressure-sensitive adhesive. For example, in the polymer block A or B, when N-vinylpyrrolidone is contained, the polarity of a phthalate such as dioctyl phthalate or dibutyl phthalate or a plasticizer such as a phosphate increases, and the adhesive force due to the transfer of the plasticizer is increased. Can be prevented from decreasing. Therefore, when forming a block copolymer for an adhesive used for a soft polyvinyl chloride base material containing a large amount of a plasticizer, it is preferable to contain N-vinylpyrrolidone.

The polymer block A or the polymer block
The glass transition temperature of block B may be measured or copolymer
In the case of-, it can be calculated using the following equation. (1 / Tg) = (W₁ / Tg₁ ) + (W_Two / Tg_Two ) + ... + (W_N / Tg_N Wherein Tg represents the glass transition temperature (K) of the copolymer
Then W₁ , W_Two ・ ・ ・ ・ ・ ・ ・ ・ ・ W _N Is the weight in the monomer composition
Fraction and Tg₁ , Tg_Two ............ Tg_N Corresponds
Of a monomer-only polymer (in the case of a homopolymer)
The lath transition temperature (K) is shown. Here, the homopolymer gas
Las transition temperature is a numerical value described in a publication such as a handbook
Should be adopted. For example, polyacrylic acid is 379
K, polymethyl acrylate is 281K, polyacrylic acid
Ethyl is 251 K, n-butyl polyacrylate is 219
K, 2-ethylhexyl polyacrylate is 203K,
Limethacrylic acid is 501K, polymethyl methacrylate is
378K, polyethyl methacrylate 338K, polymer
293K for n-butyl acrylate and 3 for polyvinyl acetate
05K, polyacrylonitrile is 398K, polystyrene
Is 373K, poly (N-vinyl-2-pyrrolidone) is
448K.

The refractive index of the polymer block A or the polymer block B may be measured or calculated by an ordinary method. In the case of calculation, it can be calculated by the following equation.

ND _xy = C _x nD _x + C _y nD _{y In the} formula, nD _xy represents a refractive index of a copolymer obtained by polymerizing monomer X and monomer Y, and C _x and _Cy each represent each of the components in the composition. Indicates the weight fraction of monomers X and Y, nD _x , nD _y
Indicates the refractive index of the homopolymer of the corresponding monomer.
Specific examples of the refractive index of the homopolymer include, for example, 1.527 for polyacrylic acid, 1.472 for polymethyl acrylate, and 1.468 for polyethyl acrylate.
5, 1.466 for polybutyl acrylate, 1.490 for polymethyl methacrylate, 1.485 for polyethyl methacrylate, and 1.47 for polybutyl isobutyl methacrylate
7. Poly (N-vinyl-pyrrolidone) is 1.530 and polystyrene is 1.590. For details, for example,
"POLYMER HANDBOOK, second e
dtion, J. et al. Bradrup and E.C. H Im
mergut, Ed. , JOHNWILEY & SON
S, NEW YORK 1975. May be referred to.

"Incompatible" means the tangent loss in dynamic viscoelasticity measurement (the ratio (G "/ G ') between storage modulus G' and loss modulus G", expressed as tan δ). Means that the number of curve peaks becomes two. That is, the peaks caused by the polymer block A and the peaks caused by the polymer block B appear separately. On the other hand, “compatible” means that the peak of the tangent loss does not separate into two but becomes one peak.
The "incompatibility" may be determined by confirming the sea-island structure when observed by a transmission electron microscope, in addition to the dynamic viscoelasticity measurement, or by comparing methanol at room temperature with respect to the initial haze value. Haze value when immersed in water for 1 hour (%)
May be confirmed by being 3 or more larger than the original haze value (%).

Here, observation with a transmission electron microscope means that an adhesive polymer at room temperature is hardened with an epoxy resin, and a very thin slice obtained with a microtome while cooling with liquid nitrogen is used for observation with a transmission electron microscope. Is placed on a metal mesh and observed after performing an appropriate treatment.

The sea-island structure is observed such that the polymer having the lower glass transition temperature (polymer block A) becomes the sea and the polymer having the higher glass transition temperature (polymer block B) becomes the island. In addition, even in the coexistence system of the polymer block A and the polymer block B having a sea-island structure, when the refractive index of the polymer block A in the sea portion is close to the refractive index of the polymer block B in the island portion. Although the contrast may not be clear, the difference from a uniform polymer is usually observable. If necessary, the functional groups can be dyed and observed.

The haze value (H) refers to the polymer block A
Is a ratio of diffuse light (D) to total light transmittance (T) when visible light is applied to the coexistence system of polymer block B and polymer block B, and is represented by H = D / T. For details, refer to Japanese Industrial Standard (JIS K 7105). Generally, it can be easily measured with a commercially available turbidimeter. For example, a turbidity meter manufactured by Nippon Denshoku Industries Co., Ltd. (Model NDH-300)
A) may be used.

Here, the initial haze value (%) is determined by measuring the haze value (%) of only the base material when the base material or the support (hereinafter collectively referred to as “base material”) is transparent. This may be corrected as a control, that is, corrected to a zero point, and then the base material coated with the polymer to be measured (25 μm in thickness after drying) may be measured as it is. Haze value after methanol treatment (%)
May be measured in the same manner after immersing only the base material in methanol in a quartz glass cell in parallel with the transparent surface of the cell to be irradiated with the measurement light beam. If the substrate is not transparent,
The transparent substrate to be transferred (good because the PET film is solvent resistant) is zero-corrected as a control, then the sample is immersed in methanol to swell, easily peeled from the substrate, and transferred to the transparent substrate Then, the value measured after evaporating the solvent after the transfer is defined as an initial haze value (%). The polymer transferred to the transparent substrate may be sandwiched using two transparent substrates so that the polymer does not peel off from the transparent substrate. However, it is necessary to perform zero point correction by superposing two substrates to be transferred.

Polymer block A and polymer block B
The reason why the haze value when immersed in methanol becomes larger than the original haze value when the two are not compatible is as follows. That is, the refractive index of methanol (20 ° C)
Is 1.326, and the refractive index of the (meth) acrylic acid alkyl ester-based polymer (for example, polyethyl methacrylate (1.4684), polymethyl acrylate (1.4
72), much lower than polyethyl acrylate (1.4684), polybutyl acrylate (1.466), polymethyl methacrylate (1.490), etc. The solubility parameter of methanol (δ: (MPa) ^1/2 ) is 2
9.7, and the solubility parameter of the (meth) acrylic polymer (for example, polymethyl acrylate (19.
8), polyethyl acrylate (19.2), polybutyl acrylate (18.0), polybutyl acrylate (18.4), polymethyl methacrylate (18.6),
Polyethyl methacrylate (18.3), polybutyl methacrylate (17.8), polybutyl methacrylate (1
6.8)), which indicates that methanol is difficult to dissolve the alkyl (meth) acrylate-based polymer. That is, the (meth) acrylic acid alkyl ester-based polymer swells a little even when immersed in methanol. If the polymer has a sea-island structure, when immersed in methanol, the swelling ratio for methanol in the sea portion of the sea-island structure is different from that of the island portion, and the amount of methanol slightly present in the sea portion and the island portion changes, The difference in the refractive index between the sea and the island increases and the cloudiness increases,
That is, it is considered that the haze value increases. In addition, examples of the solvent other than methanol include alcohols other than methanol (such as isopropanol), aliphatic hydrocarbons (such as n-hexane), and alicyclic hydrocarbons (such as cyclohexane). The measurement of the haze value (%) in the case of using a solvent other than methanol can be performed in the same manner as in the case of using methanol, and the haze value (%) in the case of isopropanol.
Is 3 or more, and in the case of cyclohexane, the haze value (%) is 1
As described above, the sea-island structure can also be confirmed by increasing from the original haze value (%).

Next, the block copolymer of the present invention and the resin composition for an adhesive containing the block copolymer will be described according to the polymerization method.

First, one embodiment of the resin composition for a pressure-sensitive adhesive of the present invention, in which a terminal represented by a general formula

[0042]

Embedded image (Wherein X is a C ₃ -C ₁₀ alkylene group, R ₁ and R
₂ represents the same or different C ₁ -C ₅ alkyl groups. )) To the polymer block B to which the peroxyester group is bonded, by adding a monomer constituting the (meth) acrylic acid alkyl ester-based polymer block A which is incompatible with the polymer block B and polymerizing it. The resin composition for a pressure-sensitive adhesive obtained will be described with reference to FIG. FIG. 1 shows a case where X is an alkylene group having 4 carbon atoms.

The polymer block B to which a peroxyester group as a raw material is bonded (hereinafter referred to as “peroxyester-polymer B”) is represented by the general formula (5) in FIG.
And is obtained by polymerizing a monomer constituting the polymer block B using the organic peroxide represented by the general formula (1) as a polymerization initiator (first-stage polymerization). In the general formula (1), R ₁ and R ₂ represent the same or different C _{1 to} C ₅ alkyl groups, respectively.

In the general formula (5), only a peroxyester group is bonded to only one side of the polymer block B. However, when the first-stage polymerization is stopped by coupling, A polymer having peroxyester groups attached on both sides may be produced.

Here, specific examples of the organic peroxide represented by the general formula (1) include 1,1-di-t-butylperoxy-2-methylcyclohexane, 1,1-di-t-hexane.
-Amyl peroxy-2-methylcyclohexane, 1,
1-di-t-hexylperoxy-2-methylcyclohexane, 1,1-di-t-octylperoxy-2-methylcyclohexane, 1,1-di-t-butylperoxy-2-methylcyclopentane, 1,1 -Di-t-butylperoxy-2-propylcyclohexane, 1,1-
Di-t-butylperoxy-2-isopropylcyclohexane, 1,1-di-t-amylperoxy-2-isopropylcyclohexane, 1,1-di-t-hexylperoxy-2-isopropylcyclohexane, 1,1-
Di-t-octyl peroxy-2-isopropylcyclohexane, 1,1-di-t-butylperoxy-2-propylcyclopentane, and the like can be mentioned.

Such an organic peroxide is cleaved to produce a peroxyester radical (3) and an alkoxy radical (2), and the peroxyester radical (3) reacts with the monomer constituting the polymer block B, and subsequently the polymerization reaction This produces peroxyester-polymer B (general formula (5)). At this time, the alkoxy radical (2) also serves as an initiator, and
Since the constituent monomers undergo a polymerization reaction, a polymer block B having an alkoxy group bonded to the terminal (see the general formula (4) in FIG. 1)
) Are generated.

The amount of the organic peroxide (1) to be added varies depending on the type of the monomer to be polymerized, but is usually 0.002% by weight or more of the charged amount of the monomer, preferably 0.1% by weight.
Not less than 01% by weight and not more than 2% by weight, preferably 1% by weight
It is as follows. If the amount is less than 0.002% by weight, the amount of the polymer having a peroxyester bond at the terminal decreases, and if it exceeds 2% by weight, the resulting polymer has a low molecular weight. Because it becomes.

As the polymerization method, conventionally known radical polymerization methods such as a solution polymerization method, a bulk polymerization method, and an emulsion polymerization method can be employed. Among them, the solution polymerization method is preferably used industrially. This is because the solution polymerization method can easily remove the heat of polymerization during the polymerization and has good workability.

Specific examples of the solvent used in the solution polymerization include aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate;
Examples thereof include alicyclic hydrocarbons such as cyclohexane; and aliphatic hydrocarbons such as hexane and pentane, but are not particularly limited as long as the polymerization reaction is not inhibited. These solvents may be used alone or in combination of two or more. The amount of the solvent used is not limited.

The polymerization conditions such as reaction temperature, reaction time, reaction pressure and the like are appropriately set according to the type of monomer used, the polymerization method, the physical properties desired for the polymer to be synthesized, the use of the resin composition for pressure-sensitive adhesive, and the like. do it. The polymerization reaction is
It is desirable to perform the treatment in an atmosphere of an inert gas such as nitrogen gas.

Next, the monomer constituting the polymer block A is added and polymerized (second stage polymerization). The polymerization carried out by adding the monomer constituting the polymer block A is started with radicals (6) and (7) generated by cleavage of the peroxyester-polymer B (5) as an initiator.

Here, peroxyester-polymer B
Can be performed by raising the temperature of the organic peroxide used as the initiator by about 10 ° C. from the temperature at which the organic peroxide was cleaved.

Under the condition that the above-mentioned cleavage of the peroxyester-polymer B occurs in the presence of the monomer constituting the polymer block A, two types of radicals (6) and (7)
Are used as initiators and the polymerization reaction proceeds, respectively. As a result, as shown in the general formula (8), a block copolymer (hereinafter referred to as “poly B-ester -Poly A block copolymer "), and a polymer block A having an alkoxy group bonded to the terminal as shown in the general formula (9). In the first-stage polymerization, when a polymer having a peroxyester group bonded to both sides of the polymer block B is produced, a poly B-ester-poly A block copolymer represented by the general formula (8) is used. Alternatively, a poly A-ester-poly B-ester-poly A block copolymer can be produced.

Accordingly, one of the block copolymers of the present invention
An embodiment is a poly B-ester-poly A block copolymer (including a poly A-ester-poly B-ester-poly A block copolymer), and the resin composition for an adhesive of one embodiment of the present invention includes poly It includes a B-ester-polyA block copolymer, a polymer block B having an alkoxy group bonded to a terminal, a polymer block A having an alkoxy group bonded to a terminal, and other solvents and oligomers.

Next, as another embodiment, the terminal is represented by the general formula

[0056]

Embedded image (Wherein X is a C ₃ -C ₁₀ alkylene group, R ₁ and R
₂ represents the same or different C ₁ -C ₅ alkyl groups. ) Is added to the (meth) acrylic acid alkyl ester-based polymer block A (hereinafter abbreviated as “peroxyester-polymer A”) to which the peroxyester group is bonded, and the monomer constituting the polymer block B is polymerized. The block copolymer obtained by the above method, the polymerization method thereof, and the resin composition for an adhesive containing the block copolymer will be described with reference to FIG. FIG. 2 shows a case where X is an alkylene group having 4 carbon atoms.

This block copolymer is the same as that of the above embodiment except that the peroxyester polymer to be polymerized in the first stage polymerization is peroxyester-polymer A, and the monomer to be added in the second stage polymerization is changed to a monomer constituting the polymer block B. It is polymerized in the same manner as the block copolymer. That is, the peroxyester-polymer A as a raw material (indicated by the general formula (11) in FIG. 2) is obtained by polymerizing the monomer constituting the polymer A using the organic oxide represented by the general formula (1) as a polymerization initiator. Is obtained by
At this time, a polymer block A (10) having an alkoxy group bonded to the terminal is also generated. Subsequently, when the monomer constituting the polymer block B is added and the conditions are such that the peroxyester-polymer A is cleaved, radicals (12) and (13) are generated and polymerization is started. As a result of the polymerization, a block copolymer represented by the general formula (14), in which the polymer block B and the polymer block A are linked by using an ester bond as a linking portion (hereinafter, abbreviated as “poly A-ester-poly B block copolymer”) And a polymer block B having an alkoxy group bonded to the terminal
(General formula (15)) is obtained.

Accordingly, another embodiment of the block copolymer of the present invention is a poly A-ester-poly B block copolymer, and the resin composition for an adhesive according to another embodiment of the present invention comprises poly A-ester-polyester. It includes a poly B block copolymer, a polymer block B having an alkoxy group bonded to a terminal, a polymer block A having an alkoxy group bonded to a terminal, other solvents, and oligomers.

The poly-B-ester-poly-A block copolymer or poly-A-ester-poly-B block copolymer of the present invention, and the resin composition for an adhesive containing the block copolymer, specifically, the polymerization method of the present invention described above The pressure-sensitive adhesive composition containing the polymer obtained by the above method has a difference between the initial haze value (%) in methanol at room temperature due to the incompatibility between the polymer block A and the polymer block B. The haze value (%) when immersed for a period of time is 3 or more larger than the original haze value (%), and the sea-island structure can be confirmed when observed with a transmission electron microscope. In such a block copolymer, a polymer block B for providing cohesive strength and an alkyl acrylate-based polymer block A for providing adhesive strength are connected to each other. The characteristics can be improved at the same time.

In the sea-island structure, the smaller the island (domain of the polymer block B) is, the more preferable it is.
Or less, more preferably 0.5 μm or less. This is because the smaller the island portion, the better the balance between adhesion and cohesion.

The content of the polymer block B in the resin composition for an adhesive of the present invention (ie, not only the block copolymer of the present invention but also the polymer block A alone and the polymer block B alone) (the polymer block in the block copolymer) B and the total amount of the polymer block B alone is 2% by weight or more, preferably 5% by weight or more, and
It is preferably at most 5% by weight, preferably at most 30% by weight. When the content of the polymer block B is less than 2% by weight (when the content of the polymer block A exceeds 98% by weight), the cohesive force of the obtained pressure-sensitive adhesive is often insufficient. On the other hand, when the content of the polymer block B exceeds 45% by weight (the content of the polymer block A is 55% by weight).
If the content is less than 10% by weight), the physical properties of the pressure-sensitive adhesive are often greatly reduced.

The weight average molecular weight of the polymer (block copolymer and polymer block A alone and polymer block B alone) contained in the pressure-sensitive adhesive resin composition of the present invention is preferably 12 × 10 ⁴ or more. Preferably it is 25 × 10 ⁴ or more.

The resin composition for a pressure-sensitive adhesive of the present invention reacts with a functional group as a crosslinking point which can be contained in the polymer block A and / or the polymer block B, specifically, the monomer b group, if necessary. The resulting crosslinking agent may be included. By using a cross-linking agent, it is possible to further polymerize the polymer block in the resin composition for an adhesive, and it is also possible to link the polymer block A and the polymer block B which exist alone by cross-linking. it can. as a result,
The cohesive force can be further improved. The cross-linking agent may be any compound having at least two functional groups per molecule that can react with the reactive functional group of the monomer b. For example, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional isocyanate compound , A metal crosslinking agent, an aziridine compound and the like.

The polyfunctional epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups per molecule. Specifically, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A / epichlorohydrin type epoxy resin, N, N, N ', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N
-Diglycidylaminomethyl) cyclohexane, N, N
-Diglycidylaniline, N, N-diglycidyltoluidine and the like.

The polyfunctional melamine compound may be a compound having two or more functional groups such as a methylol group, an alkoxymethyl group and an imino group per molecule. For example, hexamethoxymethylmelamine, hexaethoxymethylmelamine, Hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine and the like can be mentioned.

The polyfunctional isocyanate compound may be any compound having two or more isocyanate groups per molecule, such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate. , Xylylene diisocyanate, meta-xylylene diisocyanate, 1,5-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate,
Isocyanate compounds such as isophorone diisocyanate; Bullet polyisocyanate compounds such as Sumidur N (manufactured by Sumitomo Bayer Urethane); Desmodur IL, HL (manufactured by Bayer AG), Coronate E
A polyisocyanate compound having an isocyanurate ring such as H (manufactured by Nippon Polyurethane Industry Co., Ltd.); an adduct polyisocyanate compound such as Sumidur L (manufactured by Sumitomo Bayer Urethane Co., Ltd.); And adduct polyisocyanate compounds. These can be used alone or in combination of two or more. Also, blocked isocyanates in which the isocyanate groups of these polyvalent isocyanate compounds have been inactivated by reacting with a masking agent having active hydrogen can be used.

The above-mentioned metal cross-linking agent is not particularly limited. For example, aluminum, zinc, cadmium, nickel, cobalt, copper, calcium, barium, titanium, manganese, iron, lead, zirconium, chromium, tin Metal chelate compounds in which acetylacetone, methyl acetoacetate, ethyl acetoacetate, ethyl lactate, methyl salicylate, etc. are coordinated with such metals.

As the aziridine compound, N, N '
-Hexamethylene-1,6-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-
Aziridinyl propionate, bisisophthaloyl-1
-(2-methylaziridine), tri-1-aziridinyl phosphoxide, N, N'-diphenylethane-
4,4'-bis (1-aziridinecarboxamide) and the like.

When the above-mentioned crosslinking agent is contained, its content is 0.1 to 10 parts by weight based on 100 parts by weight of the polymer (block copolymer and polymer block A alone and polymer block B alone) contained in the composition. It is more preferably 0.5 to 5 parts by weight. If the amount of the crosslinking agent used is less than 0.1 part by weight, a sufficient crosslinking density cannot be obtained and the cohesive strength tends to be insufficient. On the other hand, if it exceeds 10 parts by weight, the crosslinking density becomes too high and the adhesive strength decreases. This is because there is a tendency.

The pressure-sensitive adhesive resin composition of the present invention may further contain a tackifier. Examples of the tackifier include (polymerized) rosin type, (polymerized) rosin ester type, terpene type, terpene phenol type, cumarone type, coumarone indene type, styrene resin type, xylene resin type, phenol resin type, petroleum resin type, etc. Is mentioned. These are 1
Species or a combination of two or more can be used.

When the tackifier is blended, the blending amount is not limited, but 5 parts by weight based on 100 parts by weight of the polymer (block copolymer and polymer block A alone and polymer block B alone) contained in the composition. -10
The amount is preferably 0 parts by weight, more preferably 10 parts by weight to 5 parts by weight.
An amount of 0 parts by weight is preferred. If the amount is less than 5 parts by weight, the effect of the addition of the tackifier is not recognized. On the other hand, if the amount exceeds 100 parts by weight, the tackiness is reduced and the adhesive strength may be reduced.

The resin composition for pressure-sensitive adhesive of the present invention may further contain, if necessary, additives usually used for pressure-sensitive adhesives, specifically, fillers, pigments, diluents, antioxidants, and ultraviolet absorbers. And various conventionally known additives such as an ultraviolet stabilizer. One or two or more of these additives can be appropriately added, and the amount of the additives may be appropriately selected according to desired physical properties.

The pressure-sensitive adhesive resin composition of the present invention having the above composition can be applied to the use of a conventionally known pressure-sensitive adhesive resin composition. For example, a pressure-sensitive adhesive resin composition is applied to a substrate surface, and a pressure-sensitive adhesive sheet, a pressure-sensitive label,
Various adhesive products such as adhesive tape and double-sided tape can be manufactured.

Adhesive labels and tapes are used for foods, for floor display on rough surfaces, for various graphic arts (adhesive labels for bottles, price labels, measurement labels, labels for nameplates, labels for barcodes). , Electrical wiring labels, copy paper labels, home delivery adhesive labels, business form adhesive labels, show window adhesive films, signboard adhesive films, two- and four-wheel mark / stripe tapes, marking films, sign adhesives Sheets, laminated films of printed matter, surface protection, tamper-proof labels, coupon labels, wet tissue labels, linerless labels, tire display labels and stickers (for windows, vehicles, stores), and the like. Uses of the pressure-sensitive adhesive sheet include a pressure-sensitive adhesive wallpaper, a glass scattering prevention sheet, a light-shielding sheet, and the like.

As the base material of the above-mentioned pressure-sensitive adhesive product, any of a transparent base material and other base materials can be used. Specifically, conventionally known papers such as high-quality paper, kraft paper, crepe paper, and glassine paper; polyethylene, polypropylene,
Plastics such as polyester, polystyrene, polyvinyl chloride and cellophane; rubbers such as EPDM; and foams thereof; woven fabrics and nonwoven fabrics can be used. Various shapes such as a film shape, a sheet shape, a tape shape, and a plate shape can be applied to the shape of the base material.

In the pressure-sensitive adhesive product, it is preferable to appropriately select the type of the resin composition for the pressure-sensitive adhesive, that is, the type of the block copolymer according to the type of the base material. For example, in the case of a transparent base material, the size of the island is reduced in the sea-island structure, the occupation ratio of the island is reduced, or a combination having a small difference in the refractive index between the polymer block A and the polymer block B is used. Depending on the selection, a transparent block copolymer may be used. On the other hand, when concealment is required, the size of the island is increased in the sea-island structure, the occupation ratio of the island is increased, or a combination in which the refractive index difference between the polymer block A and the polymer block B is large. By selecting, an opaque block copolymer may be used. In addition, plasticizers (phthalate esters such as dioctyl phthalate, linear dibasic esters such as dioctyl adipate, phosphate esters, etc.) contained in the base material, such as a soft polyvinyl chloride base material, may be used. In the case where a decrease in the cohesive strength of the pressure-sensitive adhesive due to migration to the pressure-sensitive adhesive layer becomes a problem, a block copolymer containing N-vinylpyrrolidone in the polymer block A or the polymer block B may be used. This is because N-vinylpyrrolidone has a function of preventing a decrease in adhesive strength due to a plasticizer.

Various known methods can be adopted as a method of applying the resin composition for an adhesive to a substrate, that is, a method of producing an adhesive product. For example, a method of directly applying the resin composition for pressure-sensitive adhesive to a base material; a method of applying the resin composition for pressure-sensitive adhesive to release paper, and then transferring the coated material to the substrate. The application equipment used when applying the pressure-sensitive adhesive resin composition to the substrate is appropriately selected according to the composition of the pressure-sensitive adhesive resin composition. The base material and the resin composition for pressure-sensitive adhesive are integrated by applying the resin composition for pressure-sensitive adhesive to one or both surfaces of the base material and then dried, and a pressure-sensitive adhesive layer (hereinafter referred to as “pressure-sensitive adhesive”) is formed on the surface of the base material. Plane ") is formed. The drying temperature is
It is appropriately selected according to the composition of the resin composition for an adhesive. When the crosslinking agent is contained in the pressure-sensitive adhesive resin composition, generally, the functional groups contained in the polymer constituting the pressure-sensitive adhesive resin composition react with the functional groups of the crosslinking agent during drying. Thus, a crosslinked structure is formed.

On the pressure-sensitive adhesive surface formed on the surface of the base material, for example, a release sheet (release paper) formed by applying a known release agent
Can be attached. Thereby, this pressure-sensitive adhesive surface can be suitably protected and stored. When a pressure-sensitive adhesive surface is formed on one surface of a base material such as a sheet or a tape, a known release agent is applied to the back surface of the base material (that is, the back surface of the pressure-sensitive adhesive surface). A release agent layer (hereinafter, referred to as “release agent surface”) may be formed. In this case, by winding the base material in a roll shape with the pressure-sensitive adhesive surface inside, the release agent surface comes into contact with the pressure-sensitive adhesive surface, and the pressure-sensitive adhesive surface can be preserved.

In some applications, the resin composition for an adhesive may be directly applied to an adherend. Further, after applying the pressure-sensitive adhesive resin composition to the release paper, by peeling the applied material from the release paper, the pressure-sensitive adhesive resin composition itself is formed into a film shape, a sheet shape, a tape shape, and a plate shape. Can be manufactured.

[0080]

EXAMPLES Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, “parts” in the examples and comparative examples below indicates “parts by weight”. [Method of preparing test piece] (1) PET film test piece Test piece of pressure-sensitive adhesive resin composition using polyethylene terephthalate (manufactured by Toray Industries, Inc., thickness of 50 μm; hereinafter abbreviated as “PET film”) as a substrate It is.

First, a resin composition for an adhesive was applied to one side of a PET film so that the thickness after drying was 25 μm, and then the resin composition for an adhesive was dried at 100 ° C. for 5 minutes. An adhesive surface was formed. Then, release paper (K-80HS manufactured by Kaken Kogyo Co., Ltd.)
(Trade name, hereinafter abbreviated as “K-80HS”)) and protected, and then the pressure-sensitive adhesive-released PET film was cured for 7 days in an atmosphere at a temperature of 23 ° C. and a relative humidity of 65%. Thus, an adhesive film (adhesive product) was obtained. Then, by cutting this adhesive film into a predetermined size, PE
A T film test piece was prepared. The release paper was peeled off from the adhesive surface when performing various measurements.

(2) PVC film test piece A flexible polyvinyl chloride film (# 380 manufactured by Mitsubishi Kasei Vinyl Co., Ltd. having a thickness of 0.1 mm as a base material;
VC film ") for the pressure-sensitive adhesive resin composition.

First, a resin composition for an adhesive was applied on release paper K-80HS so that the thickness after drying was 25 μm. The PVC film was transferred to the adhesive surface formed by drying. Thereafter, curing was performed under the same conditions as those for the PET film (in an atmosphere at a temperature of 23 ° C. and a relative humidity of 65% for 7 days) to produce a PVC film test piece. [Method of Measuring Characteristics of Resin Composition for Adhesive and Polymer] (1) Haze value Initial value and methanol treatment using a turbidity meter (Model NDH-300A) manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7105. The subsequent haze value (%) was measured.

The initial haze value was obtained by measuring the haze value of only the base material, correcting the haze value of the base material, that is, correcting the haze value to zero, and then coating the base material with the adhesive resin composition to be measured. The measurement was performed as it was, and this was used as the initial haze value. The haze value after the methanol treatment was measured in the same manner after immersing the substrate only in the methanol in a quartz glass cell in parallel with the transparent surface of the cell where the measuring beam was irradiated. (2) Viscosity It was measured at 25 ° C. using a B-type viscometer. The number of revolutions was 12 revolutions per minute. (3) Weight-average molecular weight and number-average molecular weight Both were measured by gel permeation chromatography (hereinafter abbreviated as "GPC"), and were determined by standard polystyrene conversion. [Evaluation Method] An evaluation test on the adhesive properties of the resin composition for an adhesive was performed according to the method described below in accordance with JIS Z 0237. (1) Adhesive force The initial adhesive force and the adhesive force after the heat treatment were evaluated.
The initial adhesive strength was measured for a PET film test piece and a PVC film test, and the adhesive strength after heat treatment was measured only for a PVC film test piece.

(I) Initial adhesive strength The test was performed in an atmosphere at a temperature of 23 ° C. and a relative humidity of 65%. Stainless steel plate (SUS304: hereinafter referred to as “SU”)
A tape-shaped test piece having a width of 25 mm was placed on the test piece, and the test piece was adhered to the test piece by reciprocating three times with a rubber roller having a weight of 2 kg. 2 after sticking
After 5 minutes, one end of the test piece is moved at a speed of 300 m in the 180 ° direction.
The strength at the time of peeling at m / min was measured, and this was defined as the adhesive strength (N / m).

(Ii) Adhesive force after heat treatment A PVC film test piece was heat-treated at 80 ° C. for 3 days, and then left for 1 hour in an atmosphere at 23 ° C. and a relative humidity of 65%. Next, a tape-shaped test piece having a width of 25 m was placed on an SUS plate as an adherend, and the test piece was adhered by reciprocating three times with a rubber roller having a weight of 2 kg. Twenty-five minutes after the application, one end of the test piece was moved in the 180 ° direction at a speed of 30 °.
The strength at the time of peeling at 0 m / min was measured, and this was defined as the adhesive strength after the heat treatment. (2) Holding force The PET film test piece was measured.

In an atmosphere of a temperature of 23 ° C. and a relative humidity of 65%, the area of the SUS plate to be adhered was 25 mm ×
After attaching the adhesive film so that it becomes 25 mm, 2
Five minutes later, the temperature was raised to 80 ° C., and the mixture was allowed to stand. 1 after 20 minutes
Time until adhesive film falls under a load of kg (time) or gap of adhesive film after 24 hours (mm)
Was measured. When the sample does not fall, the smaller the measured value (the smaller the deviation width), and when the sample falls, the larger the measured value (time), the better the holding force. (3) Ball tack It was measured for a PET film test piece.

The measurement was carried out in an atmosphere at a temperature of 23 ° C. and a relative humidity of 65% using an inclined ball tack device. The runway and the adhesive surface measurement section are each 100 mm, and the inclination angle is 30
°. The smaller the measured value (smaller the ball), the lower the tackiness. (4) Storage Stability of Resin Composition for Adhesive The stability of a sample bottle containing the resin composition for an adhesive was left as it was in a 40 ° C. atmosphere for one week, and the stability as a solution was visually observed. As a result, a case where no change was observed in the solution state was evaluated as “O”, a case where partial separation was observed was evaluated as “Δ”, and a case where the solution was separated into two layers was evaluated as “X”. (5) Punching workability In an atmosphere of a temperature of 23 ° C. and a relative humidity of 65%, the prepared test pieces were cut into a square having a side of 25 mm, and ten pieces were superimposed and stuck on the center of a glass plate having a side of 50 mm. Then, another glass plate was placed from above. Next, a 5 kg load was applied to the glass plate and left for one day. The load was removed, and the state of the adhesive layer was observed with a microscope. As a result, the case where the adhesive layer did not protrude was evaluated as “O”, the case where the adhesive layer slightly protruded was “Δ”, and the case where the adhesive layer protruded was large was evaluated as “X”. [Production and Evaluation of Resin Composition for Adhesive] Example 1: After polymerizing polymer block A in the first-stage polymerization, polymerizing polymer block B in the second-stage polymerization to obtain a block copolymer according to the present invention. A resin composition for a pressure-sensitive adhesive was produced.

In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser and a dropping funnel, butyl acrylate (B
A) 395.2 parts, 4 parts of acrylic acid (AA), 0.8 parts of 2-hydroxyethyl methacrylate (HEMA), and 220 parts of butyl acetate as a solvent were charged. The first-stage polymerization was carried out using 1,1-di-tert-butylperoxy-2-methylcyclohexane (a commercially available organic peroxide manufactured by NOF Corporation as Perhexa MC (trade name)) as a polymerization initiator. Start with the addition of 0.04 parts and stirring at 95 ± 2 ° C. under a stream of nitrogen.
I kept it. 8 hours after the start of the first stage polymerization,
95 parts of methyl methacrylate (methyl methacrylate) and 5 parts of acrylic acid as a monomer constituting the polymer block B and 80 parts of butyl acetate as a solvent were added. The second stage polymerization was carried out at 115 ± 2 ° C. for 8 hours. At the end of the second-stage polymerization, 880 parts of ethyl acetate was added for dilution. The diluted solution had a solid content of 27.5% by weight, a viscosity of 4960 mPa · s,
The weight average molecular weight was 63.2 × 10 ⁴ . Here, since the measured weight average molecular weight is an average molecular weight of the resin composition for an adhesive excluding only the solvent, it is a value including only the polymer block A and the polymer block B in addition to the block copolymer. .

Thereafter, the acrylic polymer solution 100
Parts (solid content: 27.5% by weight) as a crosslinking agent, Coronate L55E (a polyisocyanate compound manufactured by Nippon Polyurethane Co., Ltd .: 55% by weight of solid content, the same applies hereinafter).
Were mixed to produce the resin composition for an adhesive of Example 1.

The storage stability of the obtained pressure-sensitive adhesive resin composition was measured, and a test piece prepared using this pressure-sensitive adhesive resin composition was tested for haze value (initial and after methanol treatment), adhesive strength, The holding power, ball tack, and punching workability were measured. Table 1 shows the results. Table 1 also shows the values of the glass transition temperature (° C.) and the refractive index calculated from each monomer composition for each of the polymer blocks A and B.

Comparative Example 1: Polymer block A of Example 1
The polymer contained in the pressure-sensitive adhesive resin composition corresponds to the polymer block A alone.

That is, in the flask used in Example 1,
250 parts of 500 parts of a polymerizable unsaturated monomer comprising 494 parts of butyl acrylate, 5 parts of acrylic acid, and 1.0 part of 2-hydroxyethyl methacrylate, and 150 parts of butyl acetate as a solvent were charged. Polymerization was started by adding 0.05 parts of Perhexa MC as a polymerization initiator, and the polymerization was maintained at 115 ± 2 ° C. while stirring under a nitrogen stream. 10 minutes after the start of the polymerization, the remaining polymerizable unsaturated monomer 250
And 150 parts of a solvent (butyl acetate) were added dropwise over 1 hour, and the mixture was further reacted for 8 hours.
80 parts were added for dilution. As a result, the solid content was 28.9% by weight, the viscosity was 3290 mPa · s, and the weight average molecular weight was 68.
An 8 × 10 ⁴ acrylic copolymer solution was obtained. Coronate L55E was added as a cross-linking agent to 100 parts by weight of this acrylic polymer solution (solid content: 28.9% by weight).
Seven parts were mixed to prepare a resin composition for an adhesive of Comparative Example 1.

The storage stability of the obtained pressure-sensitive adhesive resin composition was measured, and a test piece prepared using this pressure-sensitive adhesive resin composition was tested for haze value (initial and after methanol treatment), adhesive strength, The holding power, ball tack, and punching workability were measured. Table 1 shows the results. Table 1 also shows the values of the glass transition temperature (° C.) calculated from the monomer composition of the polymer block A and the refractive index.

Comparative Example 2: Polymer block A of Example 1
And the constituent monomer of the polymer block B are uniformly polymerized in one step. The composition of the monomer constituting the polymer is 395.2 butyl acrylate.
Parts, 9 parts of acrylic acid, 0.8 part of 2-hydroxyethyl methacrylate, and 500 parts of a polymerizable unsaturated monomer composed of 95 parts of methyl methacrylate and 5 parts of acrylic acid.

The polymerization conditions and operating method were the same as in Comparative Example 1. The solid content, viscosity, and weight average molecular weight of the obtained solution were as shown in Table 1. To 100 parts by weight of this solution (solid content: 28.5% by weight), 0.5 part of Coronate L55E was mixed as a cross-linking agent to prepare a resin composition for an adhesive of Comparative Example 2.

The storage stability of the obtained pressure-sensitive adhesive resin composition was measured, and the test piece prepared using this pressure-sensitive adhesive resin composition was tested for haze value (initial and after methanol treatment), adhesive strength, The holding power, ball tack, and punching workability were measured. Table 1 shows the results. Table 1 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition.

Comparative Example 3: Polymer block A of Example 1
And a polymer block B.

That is, in the flask used in Example 1,
118.75 parts of methyl methacrylate, 6.2 of acrylic acid
Using 125 parts of the polymerizable unsaturated monomer consisting of 5 parts, a solution of the polymer block B alone was synthesized under the same conditions and operations as in Comparative Example 1. This solution had a solid content of 27.3% by weight, a viscosity of 8990 mPa · s, and a weight average molecular weight of 39.
It was 8 × 10 ⁴ . This polymer B single solution and 500 parts of the solution (polymer A single solution) synthesized in Comparative Example 1 were blended (the solid content ratio of polymer B / polymer A was 2).
0/80), to give a polymer solution of Comparative Example 3. For 100 parts of this polymer solution (solids content 28.6% by weight),
0.6 part of Coronate L55E was added as a cross-linking agent to obtain a resin composition for an adhesive of Comparative Example 3.

The storage stability of the obtained pressure-sensitive adhesive resin composition was measured, and a test piece prepared using this pressure-sensitive adhesive resin composition was tested for haze value (initial and after methanol treatment), adhesive strength, The holding power, ball tack, and punching workability were measured. Table 1 shows the results. Table 1 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition.

[0101]

[Table 1] As can be seen from Table 1, in Comparative Example 1, the cohesive force was insufficient due to the absence of the polymer block B forming the hard domain, and as a result, the holding power was inferior. In addition, even if it had an initial adhesive strength, the adhesive strength after heating was greatly reduced, and the punching workability was poor.

In Comparative Example 2, since the glass transition point was higher than that of the polymer block A capable of exhibiting adhesive strength, the adhesive strength was reduced.

In Comparative Example 3, the polymer solution was inferior in stability because it was a blend of incompatible polymers. Further, as compared with the block copolymer, the holding power and the adhesive strength after heating were low, and the punching workability was inferior.

Examples 2 to 4: Resins for pressure-sensitive adhesives in which the composition of the polymer blocks A and B was the same as in Example 1 and the content ratio of the polymer blocks A and B was changed as shown in Table 2. A composition was prepared.
The conditions and operations were the same as in Example 1 except that the amount of the solvent was changed in accordance with the total amount of the monomers to be charged, and the amount of the crosslinking agent was also changed in accordance with the amount of the crosslinking point-providing monomer (2-hydroxyethyl methacrylate). Performed by

The storage stability of the obtained pressure-sensitive adhesive resin composition was measured, and a test piece prepared using this pressure-sensitive adhesive resin composition was tested for haze value (initial and after methanol treatment), adhesive strength, The holding power, ball tack, and punching workability were measured. Table 2 shows the results. Table 2 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition, and the results of Example 1.

[0106]

[Table 2] From Table 2, as for the adhesive strength, the larger the content ratio of the polymer block B, in other words, the smaller the content ratio of the polymer block A exhibiting the adhesive strength, the smaller the adhesive properties (particularly the initial adhesive strength and the adhesive strength to PVC). It turns out that it falls. On the other hand, it is understood that the higher the content ratio of the polymer block A capable of exerting the adhesive force, the better the ball tack.

Further, it can be seen that the higher the content ratio of the polymer block B, the higher the haze value, and the lower the transparency.

Examples 5 and 6: The procedure of Example 5 was repeated except that in the monomer composition constituting the polymer block A, part of butyl acrylate was changed to N-vinylpyrrolidone (NVP). In the same way as
A resin composition for an adhesive was produced.

In Example 6, a part of butyl acrylate was changed to acrylic acid in the monomer composition constituting the polymer block A in Example 1, and methyl methacrylate was replaced with styrene (ST) in the monomer composition constituting the polymer block B. ). A resin composition for an adhesive was produced in the same manner as in Example 1, except that the amount of the solvent (butyl acetate) in the second stage polymerization (polymerization of the polymer block B) was changed to 90 parts.

The storage stability of the resin compositions for pressure-sensitive adhesives of Examples 5 and 6 was measured, and the haze values (initial and after methanol treatment) of test pieces prepared using the resin compositions for pressure-sensitive adhesives were measured. The adhesive strength, holding power, ball tack, and punching workability were measured. Table 3 shows the results. Table 3 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition, and the results of Example 1.

[0111]

[Table 3] From the comparison between Example 5 and Example 1, polymer block A
Contains N-vinylpyrrolidone, the refractive index of the polymer block A increases, and as a result, the difference in refractive index between the polymer blocks A and B decreases. That is, it can be seen that the transparency of the resin composition for an adhesive increases. On the other hand, it can be seen that since the glass transition temperature of the polymer block A exhibiting adhesive strength by including N-vinylpyrrolidone is increased, the adhesive properties (adhesive strength, holding power, and ball tack) are reduced as a whole. However, for a PVC film substrate, even if the initial adhesive force is low, the adhesive force after heating does not decrease so much, and it can be said that the adhesive properties are good for a PVC film substrate in the long term. .

From the comparison between Example 6 and Example 1, the refractive index is increased by including styrene in place of methyl methacrylate in polymer block B. The difference in the refractive index has increased. That is, although the transparency of the pressure-sensitive adhesive composition of Example 6 was lowered, in other words, the concealing property was improved. Further, in the resin composition for an adhesive of Example 6, the degree of decrease in the adhesive strength with respect to the PVC film substrate was slightly increased due to the fact that the polymer block B was of a polystyrene type.

Examples 7 to 9: Example 1 was repeated except that the monomer composition of the polymer block A in Example 1 was changed as shown in Table 4, and the content of the crosslinking agent was changed to 0.6 part. In the same manner as in the above, a resin composition for an adhesive was produced.

The storage stability of the resin compositions for pressure-sensitive adhesives of Examples 7 to 9 was measured, and the haze values (initial and after methanol treatment) of the test pieces prepared using the resin compositions for pressure-sensitive adhesives were measured. The adhesive strength, holding power, ball tack, and punching workability were measured. Table 4 shows the results. Table 4 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition, and the results of Example 1.
Shown in

[0115]

[Table 4] In Examples 7 and 9, the difference in glass transition temperature between the polymer block A and the polymer block B is small, so that the punching workability is reduced.

On the other hand, from Examples 1 and 8, it can be seen that when the difference between the glass transition temperatures of the polymer block A and the polymer block B is 60 ° C. or more, the adhesive properties and the punching workability are not significantly changed.

Example 10: Production was performed by changing the order of polymerization from that of Example 1. That is, the polymer block B was polymerized in the first stage polymerization, and the polymer block A was polymerized in the second stage polymerization.

Specifically, the same flask as that used in Example 1 was charged as a monomer constituting the polymer block B,
After charging 95 parts of methyl methacrylate and 5 parts of acrylic acid, and 80 parts of butyl acetate as a solvent, 0.04 part of perhexaMC was added as a polymerization initiator to start polymerization, and 95 ± with stirring under a nitrogen stream. The polymerization was maintained at 2 ° C. Eight hours after the start of the polymerization, 395.2 parts of butyl acrylate, 4 parts of acrylic acid and 0.8 part of 2-hydroxyethyl methacrylate as constituent monomers of polymer block A and 220 parts of butyl acetate as a solvent were added. The temperature was raised and the reaction was carried out at 115 ± 2 ° C. for 8 hours. At the end of the polymerization, 880 parts of ethyl acetate was added to dilute the polymer solution. The polymer solution after dilution has a solid content of 27.9% by weight,
Viscosity 4440 mPa · s, weight average molecular weight 5.12 × 1
0 was ^4. Coronate L was used as a crosslinking agent for 100 parts by weight of this polymer solution (solid content: 27.9% by weight).
The resin composition for an adhesive of Example 10 was prepared by mixing 0.5 part of 55E.

Example 11: The polymerization initiator was 1,1-bis (t-hexylperoxy) -2-methylcyclohexane (an organic peroxide manufactured by NOF CORPORATION
Commercially available as C (trade name), hereinafter abbreviated as “Perhexa HMC”) and the second stage (polymer block B
(Polymerization)), except that the polymerization temperature was changed to 110 ± 2 ° C., to prepare a pressure-sensitive adhesive resin composition of Example 11. The initiator used here (Perhexa HM
C) has a decomposition temperature slightly lower than that of the initiator (Perhexa MC) used in Example 1.

The storage stability of the resin compositions for pressure-sensitive adhesives of Examples 10 and 11 was measured, and the test pieces prepared using the resin compositions for pressure-sensitive adhesives were tested for haze values (initial and after methanol treatment). ), Adhesive strength, holding power, ball tack, and punching workability were measured. Table 5 shows the results. Table 5 also shows the values of the glass transition temperature (° C.) and the refractive index of the polymer calculated from the monomer composition, and the results of Example 1.

[0121]

[Table 5] From the comparison between Example 1 and Example 10, the viscosity of the pressure-sensitive adhesive resin composition obtained by reversing the polymerization order was low. This is probably because the monomer concentration at the time of polymerizing the polymer block A was lower than that of Example 1 and the molecular weight was lowered. Also, the adhesive properties were slightly different.

From a comparison between Example 1 and Example 11, it can be seen that even if the type of the initiator is changed, the adhesive properties are not significantly changed. On the other hand, the haze value of Example 10 was smaller than that of Example 1, indicating that the transparency was improved. [Polymerization Method and Identification of Obtained Polymer] Example 12: In Example 12, after obtaining polystyrene having a peroxyester group bonded to the terminal in the first-stage polymerization according to the method described in claim 3, This is intended to obtain the target block copolymer by polymerizing methyl acrylate. The outline of the polymerization reaction process is shown in FIG.
As shown in FIG. In FIG. 3, m, m ', n, n'
Indicates a positive integer.

<First Stage Polymerization (Production of Peroxyester Group-Containing Polystyrene)> In a four-necked flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel, 100 parts of styrene and solvent were added. Butyl acetate 1 as
00 parts were charged. Stir under nitrogen stream, 100 ± 2 ℃
Then, 15 parts of Perhexa MC ((1) 'in FIG. 3) was added as a polymerization initiator to initiate polymerization. Cooled 2 hours after the start of the reaction. After cooling, the polymer solution was reprecipitated in methanol to purify the polymer twice, and then dried with a vacuum drier.

The obtained polymer (corresponding to a mixture of polymer (5) '(polystyrene containing a peroxyester group) and polymer (4)' in FIG. 3) had a weight average molecular weight of 7.8 × 10 ³ and a number average molecular weight. Was 4.6 × 10 ³ . Infrared absorption spectrum of this polymer (FT-IR
Spectrum) is shown in FIG. In FIG.
A peak at 5 cm ^-1 due to a peroxyester group is seen.

Next, the polymer was analyzed by ¹³ C-NMR. The solvent used was deuterated chloroform, and the polymer concentration was about 30% by weight. The obtained ¹³ C-NMR spectrum is shown in FIG. The solvent peak (chemical shift δ of non-deuterated chloroform present in deuterated chloroform = 77.0 ppm) was used as an internal standard. 170.
A peak of the carbonyl carbon of the peroxyester group is seen at 870 ppm. At δ = 82.91 ppm, a quaternary carbon peak of a t-butyl group is observed. The calculated value of the chemical shift is described in Grant and Paul's reference (DM Grant an
d EG Paul, J. Am. Chem. Soc., 86, 2984 (196
4)) and so on.

The active oxygen content of the obtained polymer was determined by iodometry to be 1.31% by weight. This means that one molecule has 1.88 peroxide bonds calculated from the number average molecular weight. This means that the polymerization reaction is almost stopped by coupling of polystyrene radicals (for example, see "Handbook of
Polymer Synthesis ", ed. Hans R. Kricheldorf, p.8
0, see MARCEL DEKKER, INC. New York (1992)). In other words, the polymer used for identification is
It is considered that the peroxyester group-containing polystyrene radical (5) 'is coupled to have a peroxide bond at both ends.

<Second Stage Polymerization (Production of Block Copolymer)> Next, a 4-neck flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser, and a dropping funnel was charged into a four-necked flask.
10 parts of a polymer (peroxyester polystyrene) obtained by the stage polymerization, 10 parts of methyl acrylate, and 50 parts of butyl acetate as a solvent were charged. The mixture was stirred under a nitrogen stream, and the reaction was performed for 4 hours while maintaining the inside of the flask at 120 ± 2 ° C. The conversion was 99.5%. After cooling, the polymer was purified twice by reprecipitating the polymer solution in methanol, and then dried with a vacuum drier.

The polymer obtained at this stage was 73.3% of methanol insolubles and 24.8% of methanol solubles as calculated from the solid content before purification of the polymer.
The methanol-insoluble matter was the polymer (4) ′, shown in FIG.
(8) ′, whose weight average molecular weight is 1
The number average molecular weight was 1.1 × 10 ³ and 4.9 × 10 ³ . That is, the polymer obtained by the second-stage polymerization is 1
The molecular weight of the polymer obtained in the first-stage polymerization is higher than that of the polymer, and the polymerization proceeds further from the polystyrene containing a terminal peroxyester group obtained in the first-stage polymerization, whereby a block copolymer (8) ′ having a polymethyl acrylate block is obtained. It can be seen that it has been obtained. The polymer (8) 'has a polymethyl acrylate block bonded only to one side, but the polymer obtained in this embodiment may include a polymer bonded to both sides of a polystyrene block.

FIG. 6 shows the FT-IR spectrum of the methanol insoluble matter. In FIG. 6, peaks due to peroxyester groups as shown in FIG. 4 are not observed, but peaks due to polystyrene and polymethyl acrylate are observed. That is, it is understood that a block copolymer (8) ′ composed of a polystyrene block and a polymethyl acrylate block exists in the methanol insoluble matter.

On the other hand, the methanol-soluble matter is considered to be a part of the polymer (8) ′ and the polymer (9) ′ shown in FIG. FIG. 7 shows the FT-IR spectrum of the methanol-soluble matter. In FIG. 7, peaks due to polymethyl acrylate and polystyrene appear,
The peak of methyl polyacrylate is larger. That is, it is considered that the block copolymer (8) in which the polymethyl acrylate block was larger than the polystyrene block was dissolved in methanol.

Next, ¹³ C-NMR analysis of the methanol-insoluble polymer was carried out. FIG. 8 shows the obtained ¹³ C-NMR spectrum. Further, FIG. 9 shows an enlarged spectrum around 168 to 174 ppm of the result of integration of the ¹³ C-NMR spectrum. In FIG. 8, the peak of the carbonyl carbon of the peroxyester group and the peak of the quaternary carbon of the t-butyl group as shown in FIG. 5 are not seen. In FIG. 9, the peak of the carbonyl carbon of the ester group of the polymethyl acrylate block was observed from δ = 173 to 175 ppm. In addition, a peak at about 171.0 ppm, which is considered to be a carbonyl carbon in the linking portion, generated by cleavage of the peroxyester at the linking portion is observed.

Comparative Example 4: <First Stage Polymerization> 20 parts of styrene and 180 parts of toluene as a solvent were placed in a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser, and a dropping funnel. I charged. The mixture was stirred under a nitrogen stream and kept at 90 ± 2 ° C., and 2.0 parts of azobisisobutyronitrile was added as a polymerization initiator to initiate polymerization. After cooling 2 hours after the start of the reaction, the polymer solution was purified twice by reprecipitating the polymer solution in methanol and dried with a vacuum dryer. The weight average molecular weight of the obtained polymer (corresponding to polystyrene having isobutyronitrile bonded to the terminal) was 2.6 × 10 ³ , and the number average molecular weight was 2.0 × 10 ³ .

FIG. 10 shows an FT-IR spectrum of the obtained polymer (polystyrene containing isobutyronitrile group). Since this polymer does not have a peroxyester group generated by the cleavage of the initiator perhexaMC, no peak (1772.5 cm ⁻¹ ) due to this is observed. FIG. 11 shows the ¹³ C-NMR spectrum of this polymer, and the integration results of 168 to 174 p
FIG. 12 shows an enlarged spectrum around pm. In FIGS. 11 and 12, the peak of the carbonyl carbon of the peroxyester group and the peak of the quaternary carbon of the t-butyl group are not seen.

<Second Stage Polymerization> Next, 10 parts of the polymer obtained in the first stage polymerization was placed in a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser, and a dropping funnel.
10 parts of methyl acrylate and 50 parts of butyl acetate as a solvent were charged. The mixture was stirred under a nitrogen stream, and the inside of the flask was kept at 120 ± 2 ° C., and the stirring was continued for 4 hours. The solid content did not change, and no change in molecular weight due to GPC was observed.
That is, it is considered that the isobutyronitrile group at the terminal of the polymer obtained in the first stage polymerization has no function as an initiator, and no polymer growth due to polymerization occurs in the second stage.

Comparative Example 5 A four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser and a dropping funnel was charged with 30 parts of methyl acrylate and 270 parts of toluene as a solvent. Stir under nitrogen stream, 120 ±
While maintaining at 2 ° C., 6 parts of di-t-butyl peroxide (trade name: Perbutyl D, an organic peroxide manufactured by NOF Corporation) was added as a polymerization initiator to initiate polymerization. Cooled 5 hours after the start of the reaction. The polymer was purified twice by reprecipitating the polymer solution in n-hexane and dried with a vacuum drier. The weight average molecular weight of the obtained polymer (corresponding to polymethyl acrylate having a t-butoxy group at a terminal) was 9.5 × 10 ³ , and the number average molecular weight was 3.9 × 10 ³ .

FIG. 13 shows the FT-IR spectrum of the obtained polymer, and FIG. 14 shows the ¹³ C-NMR spectrum. In both FIG. 13 and FIG. 14, no peak due to the peroxyester group is observed.

Comparative Example 6 The polymer (peroxyester) obtained in the first-stage polymerization of Example 12 was placed in a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet tube, a reflux condenser, and a dropping funnel. (Including group-containing polystyrene) 10
Parts, and 10 parts of styrene, and 5 parts of butyl acetate as a solvent.
0 parts were charged. Stir under a stream of nitrogen,
The reaction was carried out at 20 ± 2 ° C. for 4 hours. The conversion is 99.
5%. After cooling, the polymer was purified twice by reprecipitating the polymer solution in methanol,
It was dried in a vacuum dryer. The obtained polymer is considered to be a polymer in which a polystyrene block is bonded via a linking unit of the following formula obtained by cleavage of a peroxyester group, and has a weight average molecular weight of 12.0 × 10 ³ ,
The number average molecular weight was 5.7 × 10 ³ .

[0138]

Embedded image Next, the polymer was subjected to ¹³ C-NMR analysis. FIG.
FIG. 5 shows its ¹³ C-NMR spectrum. FIG. 16 shows an enlarged spectrum around 168 to 174 ppm of the result of integration of this spectrum. In FIG. 16, the peak considered to be a carbonyl carbon due to the connection is represented by δ
= 170.939 ppm observed. Therefore, although it was somewhat unclear in Example 12, it is considered that the carbonyl carbon at the polymer block connecting portion can be confirmed by a peak around 171 ppm.

[0139]

According to the block copolymer of the present invention, a polymer block A capable of exerting adhesive strength and a polymer block B capable of exerting cohesive strength are bonded via a special connecting portion, so that a balance between cohesive strength and tackiness is obtained. Is excellent.
Therefore, the resin composition for an adhesive of the present invention containing the block copolymer of the present invention has excellent adhesive properties. Further, since two types of incompatible polymer blocks are contained as a block copolymer, the storage stability of the resin composition for an adhesive is excellent.

Further, by changing the monomer composition of each polymer block and the content ratio of polymer block A and polymer block B in the block copolymer of the present invention, excellent adhesive properties can be maintained, and transparency can be improved. It is possible to provide a resin composition for a pressure-sensitive adhesive depending on the use up to a high value.

Since the pressure-sensitive adhesive product of the present invention uses the resin composition for a pressure-sensitive adhesive of the present invention, it is excellent in the balance between the adhesive force and the cohesive force, and the storage stability. Various products can be provided, including those with high concealing properties.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method for polymerizing a block copolymer according to claim 4.

FIG. 2 is a diagram for explaining a method for polymerizing the block copolymer according to claim 5;

FIG. 3 is a diagram illustrating a polymerization reaction process of Example 12.

FIG. 4 is an IR spectrum of the polymer (peroxyester-containing polystyrene) obtained in the first-stage polymerization of Example 12.

FIG. 5 ¹³ C-NM of a polymer (polystyrene containing peroxyester) obtained in the first-stage polymerization of Example 12.
It is an R spectrum.

FIG. 6 shows I of methanol insolubles obtained in Example 12.
It is an R spectrum.

FIG. 7 shows I of the methanol-soluble matter obtained in Example 12.
It is an R spectrum.

FIG. 8 shows ^{13 of} methanol insolubles obtained in Example 12.
It is a C-NMR spectrum.

9 is a partially enlarged spectrum obtained by integrating the spectrum shown in FIG.

10 is an IR spectrum of a polymer (isobutyronitrile group-containing polystyrene) obtained in the first-stage polymerization of Comparative Example 4. FIG.

11 is a ¹³ C-NMR spectrum of the polymer obtained in the first-stage polymerization of Comparative Example 4. FIG.

12 is a partially enlarged spectrum obtained by integrating the spectrum shown in FIG.

FIG. 13 is an IR spectrum of a polymer (t-butoxypolymethyl acrylate) obtained in the first-stage polymerization of Comparative Example 5.

FIG. 14 is a ¹³ C-NMR spectrum of the polymer obtained in the first-stage polymerization of Comparative Example 5.

FIG. 15 shows ¹³ C-NM of the polymer obtained in Comparative Example 6.
It is an R spectrum.

16 is a partially enlarged spectrum obtained by integrating the spectrum shown in FIG.

Claims (10)

[Claims] An alkyl (meth) acrylate-based polymer block A and a polymer block B having no compatibility with the polymer block A are represented by the general formula: (Wherein, X is a C ₃ -C ₁₀ alkylene group, R ₂ is a C ₁ -C ₁₀
It represents an alkyl group of C _5. ). A block copolymer linked via a linking unit shown in ()). 2. The method according to claim 1, wherein the difference (Tg _B −Tg _A ) between the glass transition temperature (Tg _A ) of the polymer block _A and the glass transition temperature (Tg _B ) of the polymer block B is 15 ° C. or more. A block copolymer as described. 3. The block copolymer according to claim 1, wherein the haze value (%) when immersed in methanol at room temperature for 1 hour is 3 or more larger than the initial haze value (%). 4. A compound represented by the general formula:(Where X is C_Three ~ C_TenAn alkylene group of R₁ And R_Two 
Are the same or different C ₁ ~ C_Five The alkyl group of
You. ) Is bound to the peroxyester group
Compatible with polymer block B
(Meth) acrylic acid alkyl ester polymer
Polymerization by adding monomers constituting block A
A method for polymerizing a block copolymer, characterized by comprising: (5) a terminal represented by the general formula:(Where X is C_Three ~ C_TenAn alkylene group of R₁ And R_Two 
Are the same or different C ₁ ~ C_Five The alkyl group of
You. ) Is bound to the peroxyester group
(Meth) acrylic acid alkyl ester polymer block
A polymer that is not compatible with the polymer block A
Polymerization by adding the monomer constituting block B
A method for polymerizing a block copolymer, characterized by comprising: 6. A pressure-sensitive adhesive resin composition comprising the block copolymer according to claim 1. 7. The resin composition for an adhesive according to claim 6, wherein a difference between a refractive index of the polymer block A and a refractive index of the polymer block B constituting the block copolymer is 0.05 or less. Highly transparent resin composition for adhesives. 8. The resin composition for an adhesive according to claim 6, wherein the difference between the refractive index of the polymer block A and the refractive index of the polymer block B constituting the block copolymer is more than 0.05. Highly concealable resin composition for pressure-sensitive adhesive. 9. A pressure-sensitive adhesive resin composition containing the polymer obtained by the polymerization method according to claim 4. Description: 10. The method according to claim 6, wherein one or both sides of the substrate are provided.
A pressure-sensitive adhesive product comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive resin composition according to any one of the above.