JPH0977837A - Production of (meth)acrylic polymer and tacky agent containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily obtain a (meth)acrylic polymer useful for a tacky agent especially for a soft (poly)vinyl chloride resin by polymerizing a monomer composition as a raw material in the presence of a polymer immiscible with a generating polymer. SOLUTION: (A) In polymerizing a monomer composition (i) containing a carboxylic group-containing an unsaturated monomer and a monomer composition (ii) containing an unsaturated monomer containing reactive functional group other than the component (i) and an alkyl (meth)acrylate, the component (i) is polymerized and then the component (ii) is polymerized in the presence of (B) a polymer (preferably a polymer having >=273K glass transition point) immiscible with the polymer obtained by polymerizing the component A to obtain the objective (meth)acrylic polymer. The component B is readily obtained by, e.g. performing radical polymerization of at least one kind of unsaturated monomer selected from styrene, vinyl acetate, acrylonitrile, etc., by a bulk polymerization, a solution polymerization, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a (meth) acrylic polymer, which is preferably used as an adhesive for a soft polyvinyl chloride resin or a soft vinyl chloride resin, and an adhesive containing the above polymer. It is a thing.

[0002]

2. Description of the Related Art Conventionally, an adhesive sheet for soft vinyl chloride (that is, soft polyvinyl chloride resin or soft vinyl chloride resin),
(Meth) acrylic as an adhesive used in adhesive products such as adhesive tapes, adhesive labels, double-sided tapes, soft PVC adhesive sheets using soft vinyl chloride resin as a base material, soft PVC adhesive tapes, soft PVC adhesive labels, etc. A pressure-sensitive adhesive made of a polymer is known.

Usually, such an adhesive contains (meth) acrylic acid alkyl ester as a main component and is copolymerized with an α, β-unsaturated carboxylic acid such as (meth) acrylic acid in order to impart cohesive force. I am allowed to.

[0004]

However, soft vinyl chlorides include phthalic acid esters such as dioctyl phthalate and dibutyl phthalate, linear dibasic acid esters such as dioctyl adipate and dioctyl azelate, and phosphoric acid esters. And other plasticizers in a proportion of 10 to 50 parts per 100 parts of soft vinyl chloride.The problem that these plasticizers migrate to the pressure-sensitive adhesive applied to soft vinyl chloride and reduce the adhesive strength Have a point.

Further, the soft vinyl chloride contains a metal stabilizer in addition to the plasticizer. In a system containing a large proportion of the plasticizer, the adhesive strength is remarkably reduced due to the migration of the plasticizer. In a system with a small proportion of plasticizer, the metal stabilizer migrates to the adhesive side together with the plasticizer to cause metal crosslinking with the carboxyl group of α, β-unsaturated carboxylic acid such as (meth) acrylic acid, resulting in a crosslinking density. However, there is a problem that the cohesive force is increased due to the increase of the amount and the adhesiveness is reduced.

Therefore, there is a demand for a pressure-sensitive adhesive capable of maintaining sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive strength even when the plasticizer or metal stabilizer is transferred. That is, an object of the present invention is to provide a pressure-sensitive adhesive capable of maintaining sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive strength even when a plasticizer or a metal stabilizer is transferred. Another object of the present invention is to provide a method for producing a (meth) acrylic polymer used for obtaining a pressure-sensitive adhesive having the above performance.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, a monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer and a carboxyl group A monomer composition (a) comprising a reactive functional group-containing unsaturated monomer other than the group-containing unsaturated monomer and a monomer composition (a ₂ ) containing a (meth) acrylic acid alkyl ester
When polymerizing the above, the above monomer composition (a ₁ ) is polymerized in the presence of a polymer (B) which is incompatible with the polymer (A) obtained by polymerizing the monomer composition (a). And then obtained by polymerizing the monomer composition (a ₂ ) (meth)
It has been found that a pressure-sensitive adhesive containing an acrylic polymer can maintain sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive strength even when a plasticizer or a metal stabilizer migrates, and has completed the present invention. .

That is, the method for producing a (meth) acrylic polymer according to claim 1 is directed to a monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer and a carboxyl group-containing unsaturated monomer. When a monomer composition (a) consisting of a reactive functional group-containing unsaturated monomer other than the polymer and a monomer composition (a ₂ ) containing a (meth) acrylic acid alkyl ester is polymerized, After polymerizing the monomer composition (a ₁ ) in the presence of the polymer (B) which is incompatible with the polymer (A) obtained by polymerizing the body composition (a), the monomer composition It is characterized in that the substance (a ₂ ) is polymerized.

The method for producing a (meth) acrylic polymer according to claim 2 is the method according to claim 1, wherein the polymer (B) has a glass transition point of 273 K or higher. .

According to the above construction, the decrease in cohesive force due to the migration of the plasticizer and the metal stabilizer is unlikely to occur.
Even if the above-mentioned plasticizer or metal stabilizer is migrated, a pressure-sensitive adhesive that can maintain sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive force can be obtained, and a (meth) acrylic polymer can be easily obtained. . When the obtained pressure-sensitive adhesive is used as a pressure-sensitive adhesive for soft vinyl chloride, as the polymer (B),
It is preferable to use a polymer having a glass transition point of 273 K or higher.

The pressure-sensitive adhesive according to claim 3 is characterized in that it contains the (meth) acrylic polymer obtained by the production method according to any one of claims 1 and 2.

According to the above-mentioned constitution, the pressure-sensitive adhesive according to the present invention contains the (meth) acrylic polymer obtained by the above-mentioned production method, so that the cohesive force due to the migration of the plasticizer and the metal stabilizer. Is less likely to occur, and therefore, even if the plasticizer or metal stabilizer is migrated, sufficient adhesive physical properties can be maintained without a decrease in adhesive strength.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. The pressure-sensitive adhesive according to the present invention is a monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer.
And a monomer composition (a ₂ ) containing a reactive functional group-containing unsaturated monomer other than the carboxyl group-containing unsaturated monomer and a (meth) acrylic acid alkyl ester ( When polymerizing a), the monomer composition (a)
Polymer (B) that is incompatible with the polymer (A) obtained by polymerizing
After polymerizing the monomer composition (a ₁ ) in the presence of
It comprises a (meth) acrylic polymer obtained by polymerizing the monomer composition (a ₂ ).

In the above-mentioned method for producing a (meth) acrylic polymer, that is, the production method according to the present invention, the carboxyl group-containing unsaturated monomer used as a raw material is not particularly limited. Specific examples thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, and maleic anhydride. These carboxyl group-containing unsaturated monomers may be used alone or in a suitable mixture of two or more kinds.

In the method for producing a (meth) acrylic polymer according to the present invention, a reactive functional group-containing unsaturated monomer other than the carboxyl group-containing unsaturated monomer used as a raw material (hereinafter referred to as other reactivity). The functional group-containing unsaturated monomer) is not particularly limited, but specifically, for example, 2-hydroxyethyl (meth) acrylate and its polycaprolactone modified product (trade name:
Placcel F series, manufactured by Daicel Chemical Industries, Ltd., and hydroxyl group-containing unsaturated monomers such as 2-hydroxypropyl (meth) acrylate. Only one kind of these other reactive functional group-containing unsaturated monomers may be used, or two or more kinds thereof may be appropriately mixed and used.

In the method for producing a (meth) acrylic polymer according to the present invention, the (meth) acrylic acid acrylic ester used as a raw material is not particularly limited, and specifically, for example, ( Butyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic acid 4 to 18 carbon atoms such as lauryl and stearyl (meth) acrylate
(Meth) acrylic acid alkyl ester.
These (meth) acrylic acid alkyl esters may be used alone or in an appropriate mixture of two or more.

In the method for producing a (meth) acrylic acid ester-based polymer according to the present invention, the above-mentioned monomer (that is, a carboxyl group-containing unsaturated monomer, other reactive functional group) used as a raw material is used. Containing unsaturated monomers,
Required for monomers other than (meth) acrylic acid alkyl ester (hereinafter referred to as other monomers), that is, for the monomer composition (a ₁ ) and / or the monomer composition (a ₂ ). The other monomer contained according to the above is not particularly limited, and specifically, for example, aromatic unsaturated monomers such as styrene and methylstyrene; vinyl acetate, vinyl propionate, etc. Vinyl ester; N-containing unsaturated monomer such as N-vinylpyrrolidone and acryloylmorpholine; unsaturated nitrile such as (meth) acrylonitrile;
Examples thereof include unsaturated amides such as (meth) acrylamide and N-methylol acrylamide, but are not particularly limited. Only one kind of these other monomers may be used, or two or more kinds thereof may be appropriately mixed and used.

According to the production method of the present invention, a monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer
And a monomer composition (a ₂ ) containing an unsaturated monomer containing a reactive functional group and a (meth) acrylic acid alkyl ester, Polymer (A) obtained by polymerizing the monomer composition (a)
By polymerizing the monomer composition (a ₁ ) in the presence of the polymer (B) which is incompatible with ( ₁ ), the monomer composition (a ₂ ) is polymerized to obtain the desired (meth) An acrylic polymer can be easily obtained.

The monomer composition (a ₁ ) may contain, in addition to the carboxyl group-containing unsaturated monomer, the above-mentioned other monomers, if necessary. In addition, if necessary, the above-mentioned other reactive functional group-containing unsaturated monomer and (meth)
It may contain an acrylic acid alkyl ester.

On the other hand, the above-mentioned monomer composition (a ₂ ) contains, in addition to the (meth) acrylic acid alkyl ester and the above-mentioned other unsaturated monomer containing a reactive functional group, if necessary, the above-mentioned other monomer. It may include a polymer.

The content of the carboxyl group-containing unsaturated monomer in the monomer composition (a), that is, the content of the carboxyl group-containing unsaturated monomer in the monomer composition (a ₁ ) is Although not particularly limited, it is preferably within the range of 0.1% to 10% by weight, and 1% to 8% by weight.
Is more preferable. When the content of the carboxyl group-containing unsaturated monomer is less than 0.1% by weight, the cohesive force of the obtained pressure-sensitive adhesive is insufficient, which is not preferable. On the other hand, when the content of the above-mentioned unsaturated monomer containing a carboxyl group is more than 10% by weight, the cohesive force becomes too high and the adhesive force decreases, which is not preferable.

The content of the other unsaturated monomer having a reactive functional group in the monomer composition (a), that is, the monomer composition (a ₂ ) or the monomer composition (a ₁ ) And the total content of other reactive functional group-containing unsaturated monomers in the monomer composition (a ₂ ) is preferably in the range of 0.01% by weight to 2% by weight, and 0.1% by weight to 1% by weight. % Is more preferable. When the content of the above-mentioned other reactive functional group-containing unsaturated monomer is less than 0.01% by weight, the crosslinking point becomes insufficient, the crosslinking density is not sufficient, and the cohesive force is insufficient, which is not preferable. . On the other hand, the above content is 2% by weight
If it is more than the above range, the crosslink density and the cohesive force become too high, and the adhesive force decreases, which is not preferable. In addition, 0.05% by weight of the above-mentioned other unsaturated monomers containing reactive functional groups
The above is preferably contained in the monomer composition (a ₂ ),
0.1% by weight or more is more preferable.

The content of the (meth) acrylic acid alkyl ester in the monomer composition (a), that is, the monomer composition (a ₂ ), or the monomer composition (a ₁ ) and the monomer composition (a ₁ ) The total content of the (meth) acrylic acid alkyl ester in the monomer composition (a ₂ ) is preferably in the range of 68% by weight to 99.89% by weight. When the content of the (meth) acrylic acid alkyl ester is out of the above range, flexibility and tackiness as an adhesive may not be obtained, which is not preferable. In addition, it is preferable that 20% by weight or less of the (meth) acrylic acid alkyl ester is contained in the monomer composition (a ₁ ), and more preferably 10% by weight or less.

Further, the other monomer is contained in the monomer composition (a), if necessary, that is, the monomer composition (a ₁ ) and / or the monomer composition (a). _It is used so that the total content in ₂ ) is in the range of 0% by weight to 20% by weight. The content of the other monomer is not particularly limited as long as it is within the above range, but in consideration of the balance between tack and tackiness and cohesive force, the obtained (meth) acrylic polymer and It is preferably used within a range that does not impair the physical properties of the pressure-sensitive adhesive containing the (meth) acrylic polymer. If the content is more than 20% by weight, the (meth) acrylic polymer obtained may become too hard and the adhesive strength of the pressure-sensitive adhesive may decrease, which is not preferable.

The composition of the above-mentioned monomer composition (a) is used in combination so that the glass transition point (Tg) of the (meth) acrylic polymer is 200 K to 240 K from the balance of tack and adhesive strength. Is preferred.

In the method for producing a (meth) acrylic polymer according to the present invention, a polymer (B) which is incompatible with the polymer (A) obtained by polymerizing the monomer composition (a) is used. Is not particularly limited, but is obtained (meta)
When an acrylic polymer is used as a pressure-sensitive adhesive for soft PVC, a polymer having a glass transition point of 273 K or higher, that is,
High glass transition point polymers are preferred. If the glass transition point is lower than 273K, the obtained pressure-sensitive adhesive does not have sufficient cohesive force, and when the pressure-sensitive adhesive is used for soft PVC, the cohesive force due to migration of the plasticizer or metal stabilizer contained in the soft PVC. Is not preferable because there is a possibility that the decrease in

The term "incompatible" means that in the measurement of dynamic viscoelasticity of the obtained (meth) acrylic polymer,
Tangent loss (tan δ, storage modulus G ′ and loss modulus G ″
Ratio: tan δ = G ″ / G) means that the number of curve peaks becomes 2. That is, the peak due to the polymer (A) is due to the low temperature side and the peak due to the polymer (B). It means that the peak appears on the high temperature side, while “compatible” means that this tangent loss peak does not separate into two but becomes one peak.

The above polymer (B) is, for example, styrene,
Vinyl acetate, acrylonitrile, methacrylonitrile at least one unsaturated monomer selected from the group consisting of methyl methacrylate bulk polymerization method, solution polymerization method,
Alternatively, it can be easily obtained by radical polymerization by a suspension polymerization method.

As the polymer (B), it is also possible to use a commercially available thermoplastic resin which is soluble in an organic solvent used in the usual production of (meth) acrylic polymers, such as ethyl acetate and toluene. As the commercially available thermoplastic resin, for example, polystyrene, poly (acrylonitrile-styrene), polymethylmethacrylate, polyvinyl acetate or the like can be used.

Weight average molecular weight (Mw) of the polymer (B)
Is preferably 2 × 10 ⁴ or more, more preferably 5 × 10 ⁴ or more. When the weight average molecular weight is less than 2 × 10 ⁴ , when the resulting pressure-sensitive adhesive is used in soft vinyl chloride, the cohesive force may be significantly reduced due to the migration of the plasticizer and metal stabilizer contained in the soft vinyl chloride. It is not preferable because it exists.

The proportion of the monomer composition (a) and the polymer (B) added is 40 parts by weight of the polymer (B) to 60 parts by weight to 95 parts by weight of the monomer composition (a). Parts to 5 parts by weight, preferably 30 parts by weight to 10 parts by weight of the polymer (B) with respect to 70 parts by weight to 90 parts by weight of the monomer composition (a). More preferably.

If the ratio of the added amount of the monomer composition (a) is more than 95 parts by weight (that is, if the ratio of the added amount of the polymer (B) is less than 5 parts by weight), the obtained tackiness is obtained. When the agent is used in soft vinyl chloride, there is a risk that the decrease in cohesive force due to the migration of the plasticizer and metal stabilizer contained in the soft vinyl chloride may increase, which is not preferable. On the other hand, if the proportion of the monomer composition (a) added is less than 60 parts by weight (that is, the proportion of the polymer (B) added is greater than 40 parts by weight), the adhesive composition It is not preferable because the physical properties are significantly reduced.

When an acrylic graft polymer is obtained as the (meth) acrylic polymer, the monomer composition (a ₁ ) is polymerized in the presence of the polymer (B), and then the monomer composition (a ₁ ) is prepared. The desired acrylic graft polymer can be easily obtained by polymerizing the monomer composition (a ₂ ).

The polymerization method for obtaining the acrylic graft polymer, that is, the copolymerization of the monomer composition (a) and the polymer (B) is not particularly limited, and for example, radical polymerization initiation Various known methods such as a polymerization method using a polymerization initiator such as an agent; a polymerization method of irradiating with radiation such as ionizing radiation, an electron beam or the like, and an ultraviolet ray; a polymerization method by heating can be adopted. Among the above polymerization methods,
Industrially, the method using a radical polymerization initiator used for the production of ordinary acrylic pressure-sensitive adhesives is most preferable.

The radical polymerization initiator is not particularly limited, but examples thereof include organic peroxide type polymerization initiators and azo type polymerization initiators. Specific examples of the organic peroxide-based polymerization initiator include benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, and tert-butyl peroxybenzoate. Specific examples of the azo-based polymerization initiator include 2,2′-azobis (2-methylbutyronitrile) and 2,2′-azobiscyclohexanecarbonitrile. Only one kind of these polymerization initiators may be used, or two or more kinds thereof may be appropriately mixed and used. The amount of these polymerization initiators used is not particularly limited. Among the above-mentioned polymerization initiators, the organic peroxide-based polymerization initiator generates a larger amount of radicals that cause the hydrogen abstraction reaction of the (meth) acrylic polymer main chain than the azo-based polymerization initiator, whereby It is more preferable because the polymer portion derived from the monomer composition (a) can be grown from the polymer (B).

As the above-mentioned polymerization method, various conventionally known methods can be adopted and are not particularly limited. Specifically, for example, a solution polymerization method or a bulk polymerization method is used. it can. Among them, the solution polymerization method is industrially preferable. By using the solution polymerization method, it is easy to remove the heat of polymerization during the polymerization, and the workability is improved.

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. Only one of these solvents may be used, or 2
You may mix and use a kind or more suitably. The amount of solvent used is not particularly limited.

The reaction conditions such as reaction temperature and reaction time when carrying out the above-mentioned polymerization reaction are not particularly limited, and for example, an acrylic polymer having a weight average molecular weight within the range described below may be used. Depending on the composition of the monomer composition (a ₁ ), the composition of the monomer composition (a ₂ ), the type of the polymer (B) and the additive, the combination thereof, the amount used, etc. It may be set appropriately. The reaction pressure is not particularly limited, and may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure.

The acrylic graft polymer thus obtained has a weight average molecular weight of 15 × 10 ⁴ or more, preferably 20 × 10 ⁴ or more. If the weight average molecular weight of the acrylic graft polymer is less than 15 × 10 ⁴ , not only is the cohesive force after transfer of the plasticizer significantly reduced, but the initial adhesive strength may be reduced, which is not preferable.

When an acrylic block polymer is obtained as the (meth) acrylic polymer, first, a polyvalent mercaptan and styrene, vinyl acetate, acrylonitrile, or methacrylic acid capable of forming the polymer (B) are used. After polymerization with at least one unsaturated monomer selected from the group consisting of ronitrile and methyl methacrylate, the above monomer composition (a ₁ ) is added to carry out further polymerization, and then the monomer A desired acrylic block polymer can be easily obtained by adding the monomer composition (a ₂ ) and further polymerizing it.

The above-mentioned polyvalent mercaptan is a compound having two or more mercapto groups per molecule. Examples of the polyvalent mercaptan include diesters composed of diols such as ethylene glycol and 1,4-butanediol and carboxyl group-containing mercaptans; trimethylolpropane, pentaerythritol, dipentaerythritol, and other hydroxyl groups in one molecule. A polyester compound comprising a compound having 3 or more of carboxylic acid group-containing mercaptans having one mercapto group and one carboxyl group in one molecule, such as thioglycolic acid, mercaptopropionic acid, and thiosalicylic acid; Compounds having three or more mercapto groups in one molecule such as glycerin; 2-di-n-butylamino-4,6-dimercapto-S-triazine, 4,6-trimercapto-S-triazine and other triazines Valent thiols; multiple epoxy compounds A compound obtained by adding hydrogen sulfide to a poxy group to introduce a plurality of mercapto groups; an ester compound obtained by esterifying a plurality of carboxyl groups of a polyvalent carboxylic acid and mercaptoethanol, and the like, are particularly limited. is not. These polyvalent mercaptans are
Only one type may be used, or two or more types may be appropriately mixed and used.

Among the above polyvalent mercaptans, a compound having 2 to 10 mercapto groups in one molecule can efficiently produce an acrylic block polymer and has a higher performance. Since a polymer can be obtained, a compound having 3 to 6 mercapto groups in one molecule is more preferable. Among them, trimethylolpropane trithioglycolate having 3 to 6 mercapto groups in one molecule, trimethylolpropane trithiopropionate, pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, Particularly preferred is at least one compound selected from dipentaerythritol hexakisthioglycolate and dipentaerythritol hexakisthiopropionate.

The amount of polyvalent mercaptan added to the unsaturated monomer (hereinafter referred to as unsaturated monomer (b)) capable of forming the polymer (B) is not particularly limited, It is preferably 10% by weight or less, more preferably 5% by weight or less, particularly preferably 3% by weight or less.

The polymerization of the polyvalent mercaptan and the unsaturated monomer (b) can be carried out without a solvent, but may be carried out in a solvent. The solvent is not particularly limited, and the solvents exemplified above can be used.

Polymerization of the polyvalent mercaptan with the unsaturated monomer (b) (first polymerization step) is carried out by radical polymerization of the unsaturated monomer (b) starting from the polyvalent mercaptan. Is. By this radical polymerization, in each molecule of the polyvalent mercaptan, one end of the polymer portion derived from the polymer (B) is bound to the sulfur residue of one or more mercapto groups, and unreacted mercapto groups are bound. A reaction product having can be obtained. In order to carry out the above reaction efficiently, it is preferable not to add an unnecessary polymerization initiator to the reaction system.

The polymerization of the reaction product obtained in the first polymerization step and the monomer composition (a) (second polymerization step and third polymerization step) is carried out by the remaining polyvalent mercaptan. This is due to radical polymerization of the monomer composition (a) with all or part of the mercapto group being formed as the origin.

In this case, if necessary, the unreacted monomer component may be removed from the reaction product obtained in the first polymerization step, or the unreacted monomer component may be removed. Instead, it may be used in the polymerization of the reaction product and the monomer composition (a) (second polymerization step and third polymerization step).
The first polymerization step is a polymerization step of polyvalent mercaptan and the unsaturated monomer (b), and the second polymerization step is the reaction product obtained in the first polymerization step. The step of adding the monomer composition (a ₁ ) to carry out further polymerization is shown, and the third polymerization step means the step of adding the monomer composition (a ₂ ) and then carrying out further polymerization. Show.

When the monomer composition (a ₁ ) is added to the reaction product obtained in the first polymerization step, that is, when the second polymerization step is performed, the polymerization rate of the reaction mixture is 50% by weight
It is preferably not less than 80% by weight, more preferably not less than 80% by weight. When the polymerization rate is less than 50% by weight and the second polymerization step is performed, a block is formed when the second polymerization step is performed without removing unreacted monomer components remaining after the first polymerization step. The polymer (B) and the monomer composition (a
It is not preferable because it may not be possible to sufficiently introduce the properties based on the polymer portion derived from ₁ ).

The reaction product obtained in the above-mentioned polymerization step (first polymerization step), the monomer composition (a ₁ ) and the monomer composition (a ₂ ) are mixed in the second polymerization step and the third polymerization step. The polymerization method at the time of radical copolymerization in the polymerization step is not particularly limited, and various conventionally known methods such as bulk polymerization method, solution polymerization method, suspension polymerization method, and emulsion polymerization method may be used. You can Among them, in order to obtain a desired acrylic block polymer at low cost, a bulk polymerization method containing no extra volatile component is preferable.

The radical polymerization initiator used in each of the above reactions is not particularly limited, and the polymerization initiators exemplified above can be used. The amount of the polymerization initiator used is not particularly limited, but is preferably 1/2 or less of the polyvalent mercaptan, more preferably 1/10 or less, and most preferably not used, by weight.

If the above-mentioned polymerization initiator is used in a weight ratio of more than 1/2 of the polyvalent mercaptan, the desired acrylic block polymer cannot be efficiently obtained, and when the bulk polymerization method is used. The polymerization stability of is deteriorated, which is not preferable.

The reaction temperature for carrying out the above-mentioned polymerization reaction is not particularly limited, but is preferably in the range of 30 ° C to 200 ° C and stable bulk polymerization can be carried out without using a polymerization initiator. More preferably, it is in the range of 100 ° C to 150 ° C.

The reaction time for carrying out the above-mentioned polymerization reaction is not particularly limited, and the composition of the monomer composition (a ₁ ), the composition of the monomer composition (a ₂ ), the polymer (B) It may be appropriately set depending on the kind of the additive, the type of the additive, the combination thereof, the amount used, and the like. The reaction pressure is not particularly limited, and may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure.

The number average molecular weight of the acrylic block polymer is preferably in the range of 2 × 10 ³ to 1 × 10 ^6.
The range of ⁴ to 4 × 10 ⁵ is more preferable, and 2 × 10 ⁴ to 2 is more preferable.
The range of × 10 ⁵ is particularly preferable. If the number average molecular weight of the acrylic block polymer is less than 2,000, the properties as a block copolymer may not be sufficiently exhibited, which is not preferable. On the other hand, the number average molecular weight is 1 × 10
^If it is more than ⁶ , the viscosity becomes too high and the handleability may be deteriorated, which is not preferable.

The (meth) acrylic polymer thus obtained can be used as it is as a pressure-sensitive adhesive, but if necessary, an organic solvent may be added to improve coating workability. Good. The organic solvent is the (meth)
The compound is not particularly limited as long as it is a compound in which the acrylic polymer can be dissolved and / or dispersed, and specifically, for example, the solvents exemplified above can be used. The amount of the organic solvent with respect to the (meth) acrylic polymer is
Although not particularly limited, for example, within the range of 100 to 400 parts by weight, and more preferably within the range of 150 to 350 parts by weight, relative to 100 parts by weight of the (meth) acrylic polymer. . If the amount of the organic solvent with respect to the (meth) acrylic polymer is less than 100 parts by weight, the viscosity becomes too high and the coating operation may be difficult, which is not preferable. On the other hand, if the amount of the organic solvent is more than 400 parts by weight, the viscosity becomes too low and there is a possibility that coating cannot be performed, which is not preferable.

In addition, the pressure-sensitive adhesive may maintain the physical properties of the pressure-sensitive adhesive even at a high temperature, and increase the pressure-sensitive adhesive force and cohesive force with respect to an adherend having a strong polarity such as soft PVC, if necessary. You may add the crosslinking agent used for a usual adhesive. Examples of the cross-linking agent include a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional isocyanate compound, a metal cross-linking agent, and an aziridine compound, and the reactivity of the (meth) acrylic acid alkyl ester-based polymer. The compound is not particularly limited as long as it is a compound having two or more functional groups capable of reacting with the functional group per molecule.

The polyfunctional epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups per molecule, and specific examples thereof include ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl. Ether, 1,6-hexanediol diglycidyl ether, bisphenol A / epichlorohydrin type epoxy resin, N, N, N'N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylamino) Methyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like can be mentioned.

The polyfunctional melamine compound is not particularly limited as long as it is a compound having two or more functional groups of any one of a methylol group, an alkoxymethyl group and an imino group per molecule. Examples include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, and the like.

The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups per molecule, and specific examples thereof include tolylene diisocyanate (TDI), 4,
4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, 1,5-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, etc. Isocyanurates such as buret polyisocyanate compounds such as isocyanate compounds; Sumidur N (manufactured by Sumitomo Bayer Urethane Co.); Desmodur IL, HL (manufactured by Bayer AG), Coronate EH (manufactured by Nippon Polyurethane Industry Co., Ltd.) Ring-containing polyisocyanate compounds; Sumida L (manufactured by Sumitomo Bayer Urethane Co.), Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.), etc. Polyisocyanate compounds and the like. It is also possible to use a blocked isocyanate in which the isocyanate group of these polyvalent isocyanate compounds is inactivated by reacting with a masking agent having active hydrogen.

The metal cross-linking agent is not particularly limited, but specifically, for example, aluminum,
Coordinated with metals such as zinc, cadmium, nickel, cobalt, copper, calcium, barium, titanium, manganese, iron, lead, zirconium, chromium, tin, etc., acetylacetone, methyl acetoacetate, ethyl acetoacetate, ethyl lactate, methyl salicylate, etc. And metal chelate compounds.

As the aziridine compound, N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, bisisophthaloyl- 1- (2
-Methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-diphenylethane-4,4'-bis (1-aziridinecarboxamide) and the like.

These cross-linking agents may be used alone or in admixture of two or more. The amount of these cross-linking agents added to the (meth) acrylic polymer is not particularly limited, but is within the range of, for example, 0.1 parts by weight to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Is preferable, and the range of 0.5 to 5 parts by weight is more preferable. If the amount of the cross-linking agent added to the (meth) acrylic polymer is less than 0.1% by weight, the cross-linking point becomes insufficient, the cross-linking density becomes insufficient, and the cohesive force may be insufficient, which is not preferable. On the other hand, if the amount of the cross-linking agent added is more than 10 parts by weight, the cross-linking density becomes too high and the adhesive strength is lowered, which is not preferable.

Further, if necessary, a tackifier used in ordinary pressure-sensitive adhesives may be added to the pressure-sensitive adhesive.
As the tackifier, (polymerized) rosin type, (polymerized) rosin ester type, terpene type, terpene phenol type, coumarone type, coumarone indene type, styrene resin type, xylene resin type, phenol resin type, petroleum resin type, etc. Examples of the tackifier include Only one kind of these tackifiers may be used, or two or more kinds thereof may be appropriately mixed and used. The amount of these tackifiers added to the (meth) acrylic polymer is not particularly limited,
With respect to 100 parts by weight of the (meth) acrylic polymer, for example, the range of 5 to 100 parts by weight is preferable, and 10 to 50 parts by weight
The range of parts by weight is more preferable. If the addition amount of the tackifier to the (meth) acrylic polymer is less than 5% by weight, the adhesion to the adherend may not be improved, which is not preferable. On the other hand, if the addition amount of the tackifier is more than 100 parts by weight, tack may decrease and the adhesive strength may decrease, which is not preferable.

In addition to the above organic solvent, cross-linking agent and tackifier, the pressure-sensitive adhesive may also include fillers, pigments, diluents, anti-aging agents, and ultraviolet absorbers used in ordinary pressure-sensitive adhesives. A variety of conventionally known additives such as agents and UV stabilizers may be added. Only one kind of these additives may be used, or two or more kinds thereof may be appropriately mixed and used. Further, the addition amount of these additives may be appropriately set so as to obtain desired physical properties, and is not particularly limited.

The pressure-sensitive adhesive thus obtained can be used for general purposes of conventional pressure-sensitive adhesives and adhesives, but even if the plasticizer or metal stabilizer contained in the soft vinyl chloride is transferred to the pressure-sensitive adhesive, Adhesive strength can be maintained without lowering the adhesive strength, so it is an adhesive sheet for soft PVC, an adhesive tape, an adhesive label, a double-sided tape, or a soft PVC adhesive sheet, a soft PVC adhesive tape, a soft PVC adhesive label. It can be particularly preferably used as an adhesive and an adhesive for an adhesive product such as a soft vinyl chloride double-sided tape. That is, the pressure-sensitive adhesive according to the present invention includes an adhesive. The pressure-sensitive adhesive may be applied to one side or both sides of the pressure-sensitive adhesive product.

The base material used for an adhesive product using the above-mentioned adhesive is not particularly limited, but specifically, for example, paper such as kraft paper; PET (polyethylene terephthalate), soft polychlorination. Examples include sheets, tapes, foams (foams) made of plastics such as vinyl; nonwoven fabrics. Further, the above-mentioned pressure-sensitive adhesive can be used as it is without a base material.

As a method of processing an adhesive into an adhesive product,
The method is not particularly limited, and various conventionally known methods can be used. Specifically, the adhesive can be easily processed into an adhesive product by using, for example, a method of directly applying to the base material or a method of transferring what is previously applied to the release paper.

As described above, according to the production method of the present invention, the monomer composition (a ₁ ) containing the carboxyl group-containing unsaturated monomer and the other unsaturated functional group-containing unsaturated monomer are contained. When a monomer composition (a) comprising a polymer and a monomer composition (a ₂ ) containing a (meth) acrylic acid alkyl ester is polymerized, the above-mentioned monomer is present in the presence of the polymer (B). By polymerizing the monomer composition (a ₂ ) after polymerizing the composition (a ₁ ), it is difficult to reduce the cohesive force due to the migration of the plasticizer and metal stabilizer contained in the soft vinyl chloride. Therefore, even if the above plasticizer or metal stabilizer migrates, it is possible to obtain a pressure-sensitive adhesive that can maintain sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive force, and to easily obtain a (meth) acrylic polymer. You can That is, the adhesive according to the present invention,
By containing the (meth) acrylic polymer obtained by the above-mentioned production method, the decrease in cohesive force due to the migration of the plasticizer or metal stabilizer contained in the soft vinyl chloride is unlikely to occur, and therefore the plasticizer or Even if the metal stabilizer migrates, it is possible to maintain sufficient adhesive properties without lowering the adhesive strength. When the pressure-sensitive adhesive is used as a pressure-sensitive adhesive for soft vinyl chloride, it is preferable to use a high glass transition point type polymer having a glass transition point of 273K or higher as the polymer (B).

[0069]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these. In the following examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively.

The soft vinyl chloride sheet contains polyvinyl chloride resin (polymerization degree: 1,100) 100.0 parts, dioctyl phthalate 23.0 parts as a plasticizer, and barium stearate 3.0.
Part, 3.0 parts of tin-based metal stabilizer, and 15.0 parts of heavy calcium carbonate, polyvinyl chloride sheet (thickness 0.15 m
m) was used.

As for the holding power, an adhesive tape having a size of 20 mm × 20 mm is attached to a stainless steel plate (SUS304),
It was evaluated by keeping the temperature at 80 ° C for 20 minutes after pasting, applying a load of 1 kg after 20 minutes, and measuring the time until the adhesive tape drops or the deviation width of the adhesive tape after 24 hours. .

The initial adhesive strength is 25 mm wide adhesive sheet made of stainless steel (SUS) in an atmosphere of 23 ° C. and 65% RH.
A 2 kg rubber roller was reciprocated 3 times to 304), and after 25 minutes, the strength at the time of peeling in the 180 degree direction at a speed of 300 mm / min was measured and evaluated. Also, the initial adhesive force when a polypropylene plate (manufactured by Nippon Test Panel Co., Ltd., thickness 3 mm) was used instead of the stainless steel plate (SUS304) was similarly measured.

The adhesive force after heating is 80 ° C. for the adhesive sheet.
Leave it in the atmosphere for 7 days, then leave it in the atmosphere of 23 ° C. and 65% RH for 2 hours, then cut it to a width of 25 mm, and attach it to a stainless steel plate (SUS304) by reciprocating a 2 kg rubber roller 3 times. After 300 hours speed 180 degrees
It was evaluated by measuring the strength when peeled at mm / min.

In the following, "PSt-1" is polystyrene "Stylon-666R" manufactured by Asahi Kasei Corporation.
(Brand name; glass transition point: 373K, weight average molecular weight: 1
7.2 × 10 ⁴ ) and "PSt-2" is polystyrene manufactured by Asahi Kasei Corporation "Styron-G8259".
(Brand name; glass transition point: 373K, weight average molecular weight: 2
8.1 × 10 ⁴ ), “AS-1” is a styrene-acrylonitrile copolymer manufactured by Asahi Kasei Co., Ltd. “Styrac-767” (trade name; glass transition point: 377K,
Weight average molecular weight: 16.5 × 10 ⁴ ) and shows "PMMA-1"
Indicates “Sumipex-MM” (trade name; glass transition point: 378K, weight average molecular weight: 13.4 × 10 ⁴ ) which is polymethyl methacrylate manufactured by Sumitomo Chemical Co., Ltd.
"PMMA-2" means "CM-205M" (trade name; glass transition point: 378K, weight average molecular weight: 8.4 × 10 ⁴ ) which is polymethyl methacrylate manufactured by CHI MEI CORPORATION, and "BA" means butyl acrylate. "AA" indicates acrylic acid, "HEA" indicates 2-hydroxyethyl acrylate, "VP" indicates N-vinylpyrrolidone, "AAm" indicates acrylamide, and "PET".
“G” represents pentaerythritol tetrakisthioglycolate, “MMA” represents methyl methacrylate,
"St" indicates styrene, and "BMT-K40" is "Nyper B" which is an organic peroxide polymerization initiator manufactured by NOF CORPORATION.
"MT-K40" (trade name), "ABNE" indicates 2,2'-azobis (2-methylbutyronitrile) manufactured by Nippon Hydrazine Industrial Co., Ltd., and "D-160" manufactured by Arakawa Chemical Industry Co., Ltd. "Pencel D-160" (trade name; softening point 1
"L55E" is a polyisocyanate compound manufactured by Nippon Polyurethane Co., Ltd. "Coronate L55".
E "(trade name; solid content 55%), and" P-CJ "is" Pentaline C-J "(trade name; manufactured by Rika Hercules).
The softening point is 118 ° C to 128 ° C).

Example 1 In advance, the composition ratio of “AA” as the carboxyl group-containing unsaturated monomer and “BA” as the other monomer was adjusted to 1.25: 5.0,
A ”5.0 parts and BA 20.0 parts were mixed to obtain 25.0 parts of the monomer composition (a ₁ ). Further, 0.8 parts of "HEA" and 374.2 parts of "BA" were mixed so that the composition ratio of "HEA" and "BA" as other reactive functional group-containing unsaturated monomer was 0.20 to 93.55. And the monomer composition (a ₂ ) 37
I got 5.0 copies.

First, in a four-necked flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser and a dropping funnel, 210.0 parts of ethyl acetate as a solvent and "PSt-as a polymer (B)" were added. 1 "100.0 parts was charged and stirred to dissolve" PSt-1 "in ethyl acetate.

Then, 25.0 parts of the monomer composition (a ₁ ) was added to the above four-necked flask and kept at 80 ° C. with stirring under a stream of nitrogen gas to obtain "BMT-K40" as a polymerization initiator.
Polymerization was initiated by adding 0.32 part.

Two hours after the initiation of polymerization, 375.0 parts of the monomer composition (a ₂ ) and 21.0 parts of ethyl acetate were added,
"BMT-K40" (1.13 parts) was continuously added dropwise to the four-necked flask over 1.5 hours. After the dropping was completed, 447 parts of ethyl acetate and 250.7 parts of toluene as a solvent and "ABNE" as a polymerization initiator were added to the four-necked flask.
1.2 parts was added and the mixture was aged at 85 ° C. for 5 hours to obtain an acrylic polymer (hereinafter referred to as an acrylic polymer (1)).

The solid content of the acrylic polymer (1) measured by a predetermined method was 35.0%, the viscosity at 25 ° C. measured by a B-type viscometer was 3,650 mPa · s, gel permeation chromatography The polystyrene-equivalent weight average molecular weight measured by chromatography (GPC) was 44.1 × 10 ⁴ . The main reaction conditions and results are summarized in Table 1.

Then, the above acrylic polymer (1) 100
"D-1" as a tackifier with respect to parts (nonvolatile components)
After blending 24 parts of "60", "L55E" as a crosslinking agent
An adhesive was prepared by mixing 0.90 parts.

This adhesive was applied to one side of a release paper (Fujimori Kogyo Co., Ltd .: 70K-818T / EF) with a thickness after drying.
After coating so as to have a thickness of 25 μm, it was dried at 100 ° C. for 2 minutes. Next, this pressure-sensitive adhesive composition was cured at 23 ° C. for 7 days and then transferred to a soft polyvinyl chloride sheet having a thickness of 0.15 mm to obtain a pressure-sensitive adhesive sheet (with release paper). The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 2.

Example 2 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 1.
An acrylic polymer (2) was obtained. The acrylic acid ester polymer (2) measured by the same method as in Example 1 had a solid content of 34.5%, a viscosity of 7,490 mPa · s, and a weight average molecular weight of 62.3 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 1.

Using this acrylic polymer (2), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 2 to obtain a pressure-sensitive adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 2.

Example 3 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 1.
An acrylic polymer (3) was obtained. The solid content of the acrylic acid ester polymer (3) measured by the same method as in Example 1 was 34.4%, the viscosity was 3,740 mPa · s, and the weight average molecular weight was 47.9 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 1.

Using the acrylic polymer (3), a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the production conditions were changed as shown in Table 2. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 2.

Example 4 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 1.
An acrylic polymer (4) was obtained. The acrylic ester polymer (4) measured by the same method as in Example 1 had a solid content of 34.3%, a viscosity of 6,480 mPa · s and a weight average molecular weight of 49.0 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 1.

Using the acrylic polymer (4), a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the production conditions were changed as shown in Table 2. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 2.

Example 5 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 1.
An acrylic polymer (5) was obtained. The acrylic acid ester polymer (5) measured by the same method as in Example 1 had a solid content of 34.0%, a viscosity of 4,530 mPa · s, and a weight average molecular weight of 47.6 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 1.

Using this acrylic polymer (5), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 2 to obtain a pressure-sensitive adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 2.

[0090]

[Table 1]

[0091]

[Table 2]

Example 6 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 3,
An acrylic polymer (6) was obtained. The solid content of the acrylic acid ester polymer (6) measured by the same method as in Example 1 was 34.3%, the viscosity was 3,940 mPa · s, and the weight average molecular weight was 52.1 × 10 ⁴ . Table 3 shows the main reaction conditions and the results together.

Using this acrylic polymer (6), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 4 to obtain a pressure-sensitive adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 4.

Example 7 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 3.
An acrylic polymer (7) was obtained. The acrylic ester polymer (7) measured by the same method as in Example 1 had a solid content of 35.0%, a viscosity of 11,910 mPa · s and a weight average molecular weight of 51.3 × 10 ⁴ . Table 3 shows the main reaction conditions and the results together.

Using this acrylic polymer (7), a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the production conditions were changed as shown in Table 4. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 4.

Example 8 The same reaction and operation as in Example 3 were carried out except that the reaction conditions were changed as shown in Table 1.
An acrylic polymer (8) was obtained. The acrylic acid ester polymer (8) measured by the same method as in Example 1 had a solid content of 34.5%, a viscosity of 3,870 mPa · s and a weight average molecular weight of 42.3 × 10 ⁴ . Table 3 shows the main reaction conditions and the results together.

Using this acrylic polymer (8), the pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the production conditions were changed as shown in Table 4. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 4.

Example 9 The same reaction and operation as in Example 1 were carried out except that the reaction conditions were changed as shown in Table 3.
An acrylic polymer (9) was obtained. The acrylic acid ester polymer (9) measured by the same method as in Example 1 had a solid content of 34.5%, a viscosity of 4,660 mPa · s and a weight average molecular weight of 44.0 × 10 ⁴ . Table 3 shows the main reaction conditions and the results together.

Using this acrylic polymer (9), the pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the production conditions were changed as shown in Table 4. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 4.

Example 10 An acrylic polymer (10) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 3. The acrylic acid ester polymer (10) measured by the same method as in Example 1 had a solid content of 34.4% and a viscosity of 4,840 mPa · s,
The weight average molecular weight was 46.4 × 10 ⁴ . Table 3 shows the main reaction conditions and the results together.

Using this acrylic polymer (10),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 4. The holding force and the adhesive force of the obtained adhesive sheet were measured. The main manufacturing conditions and the results are summarized in Table 4.

[0102]

[Table 3]

[0103]

[Table 4]

Example 11 An acrylic polymer (11) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 5. The acrylic ester polymer (11) measured by the same method as in Example 1 had a solid content of 34.7% and a viscosity of 4,300 mPa · s,
The weight average molecular weight was 45.2 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 5.

Using this acrylic polymer (11),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 6. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 6 summarizes the main manufacturing conditions and the results.

Example 12 An acrylic polymer (12) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 5. The acrylic acid ester polymer (12) measured by the same method as in Example 1 had a solid content of 34.7% and a viscosity of 4,900 mPa · s,
The weight average molecular weight was 53.9 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 5.

Using this acrylic polymer (12),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 6. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 6 summarizes the main manufacturing conditions and the results.

Example 13 An acrylic polymer (13) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 5. The acrylic acid ester polymer (13) measured by the same method as in Example 1 had a solid content of 34.0% and a viscosity of 6,930 mPa · s,
The weight average molecular weight was 39.2 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 5.

Using this acrylic polymer (13),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 6. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 6 summarizes the main manufacturing conditions and the results.

Example 14 An acrylic polymer (14) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 5. The acrylic acid ester polymer (14) measured by the same method as in Example 1 had a solid content of 35.0% and a viscosity of 3,950 mPa · s.
The weight average molecular weight was 46.1 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 5.

Using this acrylic polymer (14),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 6. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 6 summarizes the main manufacturing conditions and the results.

[Example 15] An acrylic polymer (15) was obtained by performing the same reaction and operation as in Example 1 except that the reaction conditions were changed as shown in Table 5. Acrylic ester polymer (15) measured by the same method as in Example 1 had a solid content of 34.8% and a viscosity of 4,650 mPa · s.
The weight average molecular weight was 45.7 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 5.

Using this acrylic polymer (15),
An adhesive sheet was obtained by performing the same operations as in Example 1 except that the production conditions were changed as shown in Table 6. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 6 summarizes the main manufacturing conditions and the results.

[0114]

[Table 5]

[0115]

[Table 6]

[0116] In Comparative Example 1 Example 1, a monomer composition for comparison having a composition ratio shown in Table 7 in place of the monomer composition (a ₁₎ a (c ₁₎ using, monomer Example except that a comparative monomer composition (c ₂ ) having a composition ratio shown in Table 7 was used in place of the body composition (a ₂ ) and other reaction conditions were changed as shown in Table 7. The same reaction and operation as in 1 were carried out to obtain a comparative acrylic acid ester-based polymer (hereinafter referred to as an acrylic acid ester-based polymer (I)). The acrylic acid ester polymer (I) measured by the same method as in Example 1 had a solid content of 34.9%, a viscosity of 8,500 mPa · s, and a weight average molecular weight of 48.6 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 7.

Using this acrylic polymer (I), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 8 to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 8 summarizes the main manufacturing conditions and the results.

[Comparative Example 2] The same reaction and operation as in Comparative Example 1 were carried out except that the reaction conditions were changed as shown in Table 7.
An acrylic polymer (II) for comparison was obtained. The acrylic ester polymer (II) measured by the same method as in Example 1 had a solid content of 35.1%, a viscosity of 4,900 mPa · s, and a weight average molecular weight of 45.5 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 7.

Using this acrylic polymer (II), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 8 to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 8 summarizes the main manufacturing conditions and the results.

[Comparative Example 3] The same reaction and operation as in Comparative Example 1 were carried out except that the reaction conditions were changed as shown in Table 7.
An acrylic polymer (III) for comparison was obtained. The acrylic acid ester polymer (III) measured by the same method as in Example 1 had a solid content of 34.8%, a viscosity of 9,430 mPa · s, and a weight average molecular weight of 46.8 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 7.

Using this acrylic polymer (III), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 8, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 8 summarizes the main manufacturing conditions and the results.

[Comparative Example 4] The same reaction and operation as in Comparative Example 1 were carried out except that the reaction conditions were changed as shown in Table 7.
An acrylic polymer (IV) for comparison was obtained. The acrylic acid ester polymer (IV) measured by the same method as in Example 1 had a solid content of 34.3%, a viscosity of 4,380 mPa · s, and a weight average molecular weight of 42.6 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 7.

Using this acrylic polymer (IV), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 8 to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 8 summarizes the main manufacturing conditions and the results.

[0124]

[Table 7]

[0125]

[Table 8]

[Comparative Example 5] A monomer composition for comparison having a composition ratio shown in Table 9 instead of the monomer composition (a ₁ ) and the monomer composition (a ₂ ) in Example 1. (C ₃ ), the reaction and operation were performed in the same manner as in Example 1 except that the other reaction conditions were changed as shown in Table 9 to obtain an acrylic acid ester-based polymer for comparison (hereinafter referred to as acrylic acid). An ester polymer (V) was obtained. The acrylic acid ester polymer (V) measured by the same method as in Example 1 had a solid content of 35.1%, a viscosity of 8,900 mPa · s, and a weight average molecular weight of
It was 37.2 × 10 ⁴ . Table 9 shows the main reaction conditions and the results together.

Using this acrylic polymer (V), the same operations as in Example 1 were carried out except that the production conditions were changed as shown in Table 10, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 10 shows the main production conditions and the results together.

Comparative Example 6 The same reaction and operation as in Comparative Example 5 were carried out except that the reaction conditions were changed as shown in Table 9.
An acrylic polymer (VI) for comparison was obtained. The solid content of the acrylic acid ester polymer (VI) measured by the same method as in Comparative Example 5, ie, Example 1, was 35.2% and the viscosity was 3,3.
It was 20 mPa · s and the weight average molecular weight was 18.6 × 10 ⁴ .
Table 9 shows the main reaction conditions and the results together.

Using this acrylic polymer (VI), the same operation as in Comparative Example 5, ie, Example 1 was carried out except that the production conditions were changed as shown in Table 10 to obtain a pressure-sensitive adhesive for comparison. Got the sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 1 summarizes the main manufacturing conditions and results.
0 is shown.

[Comparative Example 7] The same reaction and operation as in Comparative Example 5 were carried out except that the reaction conditions were changed as shown in Table 9.
An acrylic polymer (VII) for comparison was obtained. The solid content of the acrylic acid ester polymer (VII) measured by the same method as in Example 1 was 34.8%, the viscosity was 5,200 mPa · s, and the weight average molecular weight was 61.2 × 10 ⁴ . Table 9 shows the main reaction conditions and the results together.

Using this acrylic polymer (VII), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 10, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 10 shows the main production conditions and the results together.

[Comparative Example 8] The same reaction and operation as in Comparative Example 5 were carried out except that the reaction conditions were changed as shown in Table 9.
An acrylic polymer (VIII) for comparison was obtained. Acrylic ester-based polymer measured by the same method as in Example 1
The solid content of (VIII) was 33.7%, the viscosity was 5,130 mPa · s, and the weight average molecular weight was 50.6 × 10 ⁴ . Table 9 shows the main reaction conditions and the results together.

Using this acrylic polymer (VIII), the same operations as in Example 1 were carried out except that the production conditions were changed as shown in Table 10, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 10 shows the main production conditions and the results together.

[Comparative Example 9] The same reaction and operation as in Comparative Example 5 were carried out except that the reaction conditions were changed as shown in Table 9.
An acrylic polymer (IX) for comparison was obtained. The solid content of the acrylic ester polymer (IX) measured by the same method as in Example 1 was 34.2%, the viscosity was 3,180 mPa · s, and the weight average molecular weight was 39.3 × 10 ⁴ . Table 9 shows the main reaction conditions and the results together.

Using this acrylic polymer (IX), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 10, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 10 shows the main production conditions and the results together.

[0136]

[Table 9]

[0137]

[Table 10]

Example 16 2.0 parts of "PETG" as polyvalent mercaptan, 0.80 part of "ABN-E" and 10.0 parts of ethyl acetate were mixed in advance to obtain 12.8 parts of a polymerization initiator solution.

On the other hand, "AA" 5.0 parts and "BA" 20.0
The parts were mixed to obtain 25.0 parts of the monomer composition (a ₁ ). Further, 374.2 parts of "BA" and 0.8 part of "HEA" were mixed to obtain 375.0 parts of the monomer composition (a ₂ ).

First, in the first polymerization step, a four-necked flask equipped with a thermometer, a stirrer, Maxblend blade (Sumitomo Heavy Industries, Ltd.), an inert gas inlet tube, a reflux condenser and a dropping funnel was installed. , 100.0 parts of "MMA" as the unsaturated monomer (b) and 60.0 parts of ethyl acetate were charged and kept at 83 ° C with stirring under a nitrogen gas stream, and 6.4 parts of 12.8 parts of the above polymerization initiator solution were charged. Was added to initiate polymerization. After the lapse of 1.5 hours from the initiation of polymerization, the remaining 6.4 parts of the polymerization initiator solution was further added to carry out further polymerization. The polymerization rate after 8 hours from the start of the reaction was 85.1%.

Then, in the second polymerization step, 25.0 parts of the monomer composition (a ₁ ) and 20.0 parts of ethyl acetate were added to the four-necked flask, and the reaction was continued for another hour.

Then, as the third polymerization step, 375.0 parts of the monomer composition (a ₂ ) and 365.0 parts of ethyl acetate were continuously added dropwise to the above 4-neck flask over 2 hours. After the dropping was completed, 10 parts of ethyl acetate and "A" were added to the four-necked flask.
0.2 part of "BN-E" was added and the mixture was aged at 85 ° C for 2 hours to obtain an acrylic acid ester polymer (hereinafter referred to as an acrylic acid ester polymer (16)).

The solid content of the acrylic ester polymer (16) measured by the same method as in Example 1 was 50.9%,
Viscosity is 4,780 mPa · s, weight average molecular weight is 30.1 × 1
0 ⁴ , and the number average molecular weight was 5.0 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 11.

Using this acrylic polymer (16),
Example 1 except that the manufacturing conditions were changed as shown in Table 12.
The same operation as above was performed to obtain an adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 12 shows the main production conditions and the results together.

Example 17 An acrylic polymer (17) was obtained by performing the same reaction and operation as in Example 16 except that the reaction conditions were changed as shown in Table 11. Example 16,
That is, the solid content of the acrylic acid ester polymer (17) measured by the same method as in Example 1 was 50.4%, and the viscosity was
The mass average molecular weight was 4,650 mPa · s, the weight average molecular weight was 32.4 × 10 ⁴ , and the number average molecular weight was 5.1 × 10 ⁴ . The main reaction conditions and the results are summarized in Table 11.

Using this acrylic polymer (17),
Example 1 except that the manufacturing conditions were changed as shown in Table 12.
6, ie, the same operation as in Example 1 was performed to obtain an adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 12 shows the main production conditions and the results together.

[Example 18] An acrylic polymer (18) was obtained by performing the same reaction and operation as in Example 16 except that the reaction conditions were changed as shown in Table 11. The acrylic acid ester polymer (18) measured by the same method as in Example 1 had a solid content of 50.1% and a viscosity of 5,240 mPa · s.
Weight average molecular weight 36.1 × 10 ⁴ , number average molecular weight 5.3 × 10
^{Was 4} . The main reaction conditions and the results are summarized in Table 11.

Using this acrylic polymer (18),
Example 1 except that the manufacturing conditions were changed as shown in Table 12.
The same operation as above was performed to obtain an adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 12 shows the main production conditions and the results together.

Example 19 An acrylic polymer (19) was obtained by performing the same reaction and operation as in Example 16 except that the reaction conditions were changed as shown in Table 11. The acrylic acid ester polymer (19) measured by the same method as in Example 1 had a solid content of 50.9% and a viscosity of 14,300 mPa · s,
Weight average molecular weight 36.1 × 10 ⁴ , number average molecular weight 5.3 × 10
^{Was 4} . The main reaction conditions and the results are summarized in Table 11.

Using this acrylic polymer (19),
Example 1 except that the manufacturing conditions were changed as shown in Table 12.
The same operation as above was performed to obtain an adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 12 shows the main production conditions and the results together.

Example 20 An acrylic polymer (20) was obtained by performing the same reaction and operation as in Example 16 except that the reaction conditions were changed as shown in Table 11. The acrylic ester polymer (20) measured by the same method as in Example 1 had a solid content of 50.8% and a viscosity of 5,480 mPa · s.
Weight average molecular weight 31.3 × 10 ⁴ , number average molecular weight 5.1 × 10
^{Was 4} . The main reaction conditions and the results are summarized in Table 11.

Using this acrylic polymer (20),
Example 1 except that the manufacturing conditions were changed as shown in Table 12.
The same operation as above was performed to obtain an adhesive sheet. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 12 shows the main production conditions and the results together.

[0153]

[Table 11]

[0154]

[Table 12]

[0155] In Comparative Example 10] In Example 16, the monomer composition for comparison having a composition ratio shown in Table 13 in place of the monomer composition (a ₁₎ a (c ₁₎ using, monomer Body composition (a
Monomer composition for comparison having a composition ratio shown in Table 13 in place of ₂₎ (c ₂₎ was used, other except that the reaction conditions were changed as shown in Table 13 the same reaction as in Example 16 -The operation was performed to obtain a comparative acrylic polymer (X). Example 16, that is, the solid content of the acrylic acid ester polymer (X) measured by the same method as in Example 1 was 50.3%, the viscosity was 3,480 mPa · s, the weight average molecular weight was 28.1 × 10 ⁴ ,
The number average molecular weight was 4.4 × 10 ⁴ . Table 13 shows the main reaction conditions and the results together.

Example 1 was repeated except that the production conditions were changed as shown in Table 14 using this acrylic polymer (X).
6, ie, the same operation as in Example 1 was performed to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 1 summarizes the main manufacturing conditions and results.
4 shows.

[Comparative Example 11] Acrylic polymer (XI) for comparison was obtained by performing the same reaction and operation as in Comparative Example 10 except that the reaction conditions were changed as shown in Table 13. Comparative Example 10, that is, the solid content of the acrylic ester polymer (XI) measured by the same method as in Example 1 was 50.2%, the viscosity was 4,850 mPa · s, the weight average molecular weight was 33.4 × 10 ⁴ ,
The number average molecular weight was 5.4 × 10 ⁴ . Table 13 shows the main reaction conditions and the results together.

Comparative Example 1 using this acrylic polymer (XI), except that the production conditions were changed as shown in Table 14.
0, that is, the same operation as in Example 1 was performed to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 1 summarizes the main manufacturing conditions and results.
4 shows.

[Comparative Example 12] An acrylic polymer (XII) for comparison was obtained by performing the same reaction and operation as in Comparative Example 10 except that the reaction conditions were changed as shown in Table 13. The acrylic ester polymer (XII) measured by the same method as in Example 1 had a solid content of 50.1% and a viscosity of 12,240 mP.
a ・ s, weight average molecular weight is 38.1 × 10 ⁴ , number average molecular weight is
It was 5.9 × 10 ⁴ . Table 13 shows the main reaction conditions and the results together.

Using this acrylic polymer (XII),
Example 1 except that the manufacturing conditions were changed as shown in Table 14.
The same operation as above was performed to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 14 shows the main manufacturing conditions and the results together.

Comparative Example 13 A comparative acrylic polymer (XIII) was obtained by performing the same reaction and operation as in Comparative Example 10 except that the reaction conditions were changed as shown in Table 13. The acrylic acid ester polymer (XIII) measured by the same method as in Example 1 had a solid content of 50.6% and a viscosity of 4,880 mPa · s.
s, weight average molecular weight is 30.8 × 10 ⁴ , number average molecular weight is 5.0
It was × 10 ⁴ . Table 1 is a summary of the main reaction conditions and results.
3 is shown.

Using this acrylic polymer (XIII), the same operation as in Example 1 was carried out except that the production conditions were changed as shown in Table 14, to obtain a pressure-sensitive adhesive sheet for comparison. The holding force and the adhesive force of the obtained adhesive sheet were measured. Table 14 shows the main manufacturing conditions and the results together.

[0163]

[Table 13]

[0164]

[Table 14]

As is clear from the results of Examples 1 to 20 and Comparative Examples 1 to 13, the pressure-sensitive adhesive containing the (meth) acrylic polymer obtained by the production method of the present invention was used. The obtained pressure-sensitive adhesive sheet is excellent in holding power and pressure-sensitive adhesive strength after heating, as compared with the pressure-sensitive adhesive sheet obtained using the pressure-sensitive adhesive containing the (meth) acrylic polymer obtained in Comparative Example. I found out that That is, it was found that the pressure-sensitive adhesive obtained in this example can maintain sufficient pressure-sensitive adhesive physical properties without lowering the pressure-sensitive adhesive force even when the plasticizer or metal stabilizer contained in the soft vinyl chloride sheet migrates. .

[0166]

As described above, the method for producing a (meth) acrylic polymer according to the first aspect of the present invention provides a monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer. A monomer composition (a ₂ ) containing a reactive functional group-containing unsaturated monomer other than the carboxyl group-containing unsaturated monomer and a (meth) acrylic acid alkyl ester (a ₂ ). In the presence of a polymer (B) which is incompatible with the polymer (A) obtained by polymerizing the monomer composition (a), the above-mentioned monomer composition (a ₁ ) is polymerized. Then, the monomer composition (a ₂ ) is polymerized.

As described above, the method for producing a (meth) acrylic polymer according to claim 2 of the present invention is a method in which the glass transition point of the polymer (B) is 273 K or higher.

According to the above construction, the decrease in cohesive force due to the migration of the plasticizer and the metal stabilizer is unlikely to occur.
Even if the above-mentioned plasticizer or metal stabilizer is migrated, a pressure-sensitive adhesive that can maintain sufficient pressure-sensitive adhesive properties without lowering the pressure-sensitive adhesive force can be obtained, and a (meth) acrylic polymer can be easily obtained. Has the effect. When the obtained pressure-sensitive adhesive is used as a pressure-sensitive adhesive for soft vinyl chloride, a polymer having a glass transition point of 273 K or higher is preferably used as the polymer (B).

As described above, the pressure-sensitive adhesive according to the third aspect of the present invention comprises the (meth) acrylic polymer obtained by the above-mentioned production method.

According to the above-mentioned constitution, the pressure-sensitive adhesive according to the present invention contains the (meth) acrylic polymer obtained by the above-mentioned production method, so that the cohesive force due to the migration of the plasticizer and the metal stabilizer is obtained. Is less likely to occur, and therefore, even if the plasticizer or metal stabilizer is migrated, sufficient adhesive properties can be maintained without a decrease in adhesive strength.

Claims (3)

[Claims] 1. A monomer composition (a ₁ ) containing a carboxyl group-containing unsaturated monomer, and a reactive functional group-containing unsaturated monomer other than the carboxyl group-containing unsaturated monomer and (meth). When polymerizing a monomer composition (a) comprising a monomer composition (a ₂ ) containing an alkyl acrylate, a polymer (A) obtained by polymerizing the monomer composition (a) and In the presence of the incompatible polymer (B), the monomer composition (a
_A method for producing a (meth) acrylic polymer, which comprises polymerizing the monomer composition (a ₂ ) after polymerizing ₁ ). 2. The glass transition point of the polymer (B) is 273.
It is K or more, (meta) according to claim 1,
A method for producing an acrylic polymer. 3. A pressure-sensitive adhesive comprising a (meth) acrylic polymer obtained by the method according to claim 1 or 2.