JP6419627B2 - Adhesive composition and adhesive film - Google Patents

Description

  The present invention relates to an adhesive composition and an adhesive film.

  When processing or transporting articles such as metal plates, painted steel plates, and synthetic resin plates, adhesive films are applied to protect the surfaces of the articles from damage, dirt, etc. . The adhesive film is peeled off from the article when protection of the article is no longer necessary. The pressure-sensitive adhesive film used here generally has a pressure-sensitive adhesive layer for attaching to an article (hereinafter also referred to as “adhered body”) on one side of a sheet-like base material.

  The pressure-sensitive adhesive layer of the pressure-sensitive adhesive film has such a degree of adhesiveness that it does not cause displacement on the surface of the adherend or fall off from the surface of the adherend while protection of the adherend is required. It is required to be easily peelable from the adherend (hereinafter also referred to as “peelability”) at the stage where the protection of the adherend becomes unnecessary.

  In addition, the adherend may be heat-treated in a state protected by an adhesive film. In general, the adhesive film is difficult to peel off from the adherend due to an increase in the adhesive force of the adhesive layer, for example, by heat treatment at 100 ° C. For this reason, the adhesive film is required to have good peelability even after heat treatment.

  In response to these requirements, Patent Document 1 discloses a pressure-sensitive adhesive composition in which a reactive oligomer is added to an acrylic polymer as a pressure-sensitive adhesive having a small increase in adhesive strength even after heat treatment. Patent Document 2 discloses a pressure-sensitive adhesive composition containing an acrylic high molecular weight copolymer having a functional group and an acrylic low molecular weight copolymer having a functional group.

JP 2003-277707 A JP 2008-38103 A

Generally, it is known that the force for peeling an adhesive film from an adherend (hereinafter also referred to as “peeling force”) varies depending on the peeling rate (hereinafter also referred to as “peeling rate dependency”). Yes. Moreover, there exists a tendency for big peeling force to be required, so that peeling speed is high. The pressure-sensitive adhesive film that has been heat-treated has an increased adhesive strength of the pressure-sensitive adhesive layer, and may be difficult to peel off from the adherend, and is also referred to as “high-speed peelability” (hereinafter, “high-speed peelability”). ) Is likely to get worse.
If the high-speed peelability is inferior, it may be possible to peel at a low speed, but peeling at a low speed is inefficient.
Therefore, the adhesive film is required to be excellent in high-speed peelability from the viewpoint of increasing the peeling speed and improving the efficiency.

Moreover, since the peeling speed of the adhesive film is not constant, depending on the peeling speed, the adhesive film may be difficult to peel from the adherend and may be damaged.
For this reason, the adhesive film is also required to have a peeling force that hardly changes even if the peeling speed changes, that is, it has a low dependence on the peeling speed.

  On the other hand, in Patent Documents 1 and 2 described above, no study has been made on the high-speed peelability after heat treatment and the peel rate dependency. In addition, when the conventional pressure-sensitive adhesive composition as described in Patent Documents 1 and 2 described above has high-speed peelability and peel-speed dependency after heat treatment are not at a level sufficient for recent requirements. I found out that

This invention is made | formed in view of the above situations, and provides the adhesive composition which can manufacture the adhesive film which is excellent in the high speed peelability after heat processing, and has low peeling rate dependence. Is an issue.
Another object of the present invention is to provide a pressure-sensitive adhesive film that includes a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition, is excellent in high-speed peelability after heat treatment, and has low peel rate dependency.

Specific means for solving the problems include the following aspects.
<1> a (meth) acrylic polymer containing a structural unit derived from a monomer having a carboxy group, having an acid value of 40 mgKOH / g or more and 90 mgKOH / g or less, and a weight average molecular weight of 300000 or more and 1800000 or less,
A crosslinking agent;
Including terpene phenolic tackifier,
The adhesive composition whose content of the said terpene phenol-type tackifier with respect to 100 mass parts of said (meth) acrylic-type polymers is 0.1 mass part or more and 5 mass parts or less.

<2> comprising a structural unit derived from a monomer having a carboxy group, further comprising a (meth) acrylic oligomer having an acid value of 70 mgKOH / g or more and a weight average molecular weight of 1,000 to 30,000,
The ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass or more and 40% by mass or less,
The content of the terpene phenol tackifier is the content of the terpene phenol tackifier with respect to a total of 100 parts by mass of the (meth) acrylic polymer and the (meth) acrylic oligomer,
The pressure-sensitive adhesive composition according to <1>, wherein the total acid value calculated by the following formula is 40 mgKOH / g or more and 90 mgKOH / g or less.

<3> The content of the crosslinking agent is a function that contributes to crosslinking with respect to a total of 1 equivalent of the carboxy group contained in the (meth) acrylic polymer and the carboxy group contained in the (meth) acrylic oligomer. <2> The pressure-sensitive adhesive composition according to <2>, wherein the amount of the group is 0.5 equivalent to 2.0 equivalent.

<4> The structural unit derived from a monomer having a glass transition temperature (Tg) of −50 ° C. or less when the (meth) acrylic oligomer is a homopolymer is defined as all structural units of the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to <2> or <3>, containing 50% by mass or more based on

<5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, wherein a glass transition temperature (Tg) of the (meth) acrylic polymer is −50 ° C. or lower.

<6> The pressure-sensitive adhesive composition according to any one of <1> to <5>, wherein the crosslinking agent is at least one selected from the group consisting of an epoxy compound and an isocyanate compound.

A pressure-sensitive adhesive film comprising a <7> base material and a pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition according to any one of <1> to <6>.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can manufacture the adhesive film which is excellent in the high-speed peelability after heat processing and has low peeling rate dependence can be provided.
In addition, according to the present invention, it is possible to provide a pressure-sensitive adhesive film that includes the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition, is excellent in high-speed peelability after heat treatment, and has low peel rate dependency.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

In the present specification, a numerical range indicated using “to” means a range including the numerical values described before and after “to” as a minimum value and a maximum value, respectively.
In this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. .

In this specification, the “pressure-sensitive adhesive composition” refers to a liquid or paste-like composition after mixing a (meth) acrylic polymer, an isocyanate compound, and a terpenephenol tackifier and before the crosslinking reaction is completed. Means a substance.
In the present specification, the “pressure-sensitive adhesive layer” means a substance after the crosslinking reaction of the pressure-sensitive adhesive composition is completed.
In the present specification, “(meth) acrylic polymer” or “(meth) acrylic oligomer” means a polymer in which at least a monomer as a main component is a monomer having a (meth) acryloyl group among the monomers constituting these. Or an oligomer is meant. The monomer as the main component here means a monomer having the largest content (mass%) among monomers constituting the polymer or oligomer. In an embodiment of the (meth) acrylic polymer or (meth) acrylic oligomer in the present invention, the content of the structural unit derived from the monomer having the (meth) acryloyl group as the main component is 50% by mass of the total structural unit. That's it.
In the present specification, “(meth) acryl” means both “acryl” and “methacryl”, “(meth) acrylate” means both “acrylate” and “methacrylate”, and “(meth) acryloyl” Means both “acryloyl” and “methacryloyl”.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention comprises a structural unit derived from a monomer having a carboxy group, has an acid value of 40 mgKOH / g or more and 90 mgKOH / g or less, and a weight average molecular weight of 300000 or more and 1800000 or less. A polymer, a crosslinking agent, and a terpene phenolic tackifier, and the content of the terpene phenolic tackifier with respect to 100 parts by mass of the (meth) acrylic polymer is 0.1 parts by mass or more and 5 parts by mass or less. is there.

  By satisfy | filling the said requirements, the adhesive composition of this invention turns into an adhesive composition which can manufacture the adhesive film which is excellent in the high-speed peelability after heat processing, and has low peeling rate dependence.

In general, a tackifier (tackifier) is used by being added to an adhesive composition in order to increase the adhesive force and tack force.
The present inventor unexpectedly suppresses an increase in the adhesive strength due to heating when a pressure-sensitive adhesive composition containing a small amount of a terpene phenol-based tackifier together with a (meth) acrylic polymer containing a carboxy group and a crosslinking agent is suppressed. The present inventors have found that, at the time of high-speed peeling, good peelability is exhibited, and the dependency of adhesive force on the peeling speed can be suppressed to a low level.
The reason why the pressure-sensitive adhesive composition of the present invention can exhibit such an effect is not clear, but the present inventor presumes as follows.

  Generally, in an adhesive film, the adhesive force of an adhesive layer rises by heating. The increase in the adhesive force is caused by the resin becoming soft by heating and excessively spreading on the adherend. Moreover, the force (peeling force) for peeling the pressure-sensitive adhesive film from the adherend has a peeling speed dependency, and the higher the peeling speed, the larger the peeling force is required. The heated pressure-sensitive adhesive film tends to be inferior in high-speed peelability since the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is increased.

  In the pressure-sensitive adhesive composition of the present invention, a (meth) acrylic polymer and a small amount of terpene phenol-based tackifier that does not increase adhesive strength and tack are cross-linked via a cross-linking agent to form a cross-linked body. . The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention has an acid value of 40 mgKOH / g or more and 90 mgKOH / g or less, and has a sufficient amount of crosslinking points with many acidic groups which are crosslinkable functional groups. In addition, the tackifier has a phenolic hydroxyl group having good reactivity with the cross-linking agent, so that the formed cross-linked body is closely cross-linked and hard. If the cross-linked body is hard, the (meth) acrylic polymer portion is difficult to spread excessively on the adherend due to heating, and an increase in adhesive force due to heating is suppressed, so that it is considered that high-speed peelability is excellent.

In general, the peel rate dependency of the adhesive force is determined by the balance between the viscoelasticity of the adhesive layer and the wettability to the adherend.
In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer and the terpene phenolic tackifier are cross-linked via a cross-linking agent, so that the balance between viscoelasticity and wettability can be obtained, so that the peeling speed It is considered that the dependency is kept low.

  In addition, in the adhesive composition of this invention, since the functional group used as a crosslinking point is a carboxy group, it has the advantage that it can bridge | crosslink without using a crosslinking catalyst.

  The pressure-sensitive adhesive composition of the present invention includes a structural unit derived from a monomer having a carboxy group, an acid value of 70 mgKOH / g or more, and a weight average molecular weight of 1000 to 30000 (meth) acrylic oligomer (hereinafter referred to as “a”). In addition, the ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass. The content of the terpene phenolic tackifier is 40% by mass or less, and the content of the terpene phenolic tackifier is 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer. The total acid value calculated by the following formula is 40 mgKOH It is preferably g or more 90 mgKOH / g or less.

In the pressure-sensitive adhesive composition of the present invention, as the oligomer contained in the pressure-sensitive adhesive composition, an (meth) acrylic oligomer having an acid value of 70 mgKOH / g or more and a large number of crosslinking points is used. , The crosslinked body becomes hard. For this reason, compared with the case where an oligomer is not used, excessive wetting and spreading to the adherend due to heating is suppressed, and more excellent high-speed peelability and lower peel dependency are exhibited.
In general, when the adhesive film is peeled from the adherend, the adherend may be contaminated, and the adherend may need to be discarded. Therefore, the adhesive film is required to have a low property of contaminating the adherend (hereinafter also referred to as “contamination”), that is, it is difficult to contaminate the adherend. Furthermore, the pressure-sensitive adhesive composition containing an oligomer tends to contaminate the adherend because the oligomer tends to remain on the surface of the adherend upon peeling. In particular, when the adhesive force of the pressure-sensitive adhesive layer is increased by the heat treatment and is difficult to peel, the surface of the adherend is more easily contaminated.
On the other hand, in the pressure-sensitive adhesive composition of the present invention, there are many crosslinking points of the oligomer contained in the pressure-sensitive adhesive composition, and since there are few uncrosslinked oligomers, it is difficult to contaminate the adherend and exhibits low contamination. .

  In the present specification, the “acid value of (meth) acrylic polymer” is determined by the following calculation formula. In the following calculation formula, 56.1 is the molecular weight of KOH.

  When there are two or more monomers having a carboxy group used in the (meth) acrylic polymer, the acid value is determined according to the above calculation formula for each monomer, and the obtained values are summed to determine the acid value. Ask for.

  In the present specification, the “acid value of (meth) acrylic oligomer” is determined by the following calculation formula. In the following calculation formula, 56.1 is the molecular weight of KOH.

  When there are two or more monomers having a carboxy group used in the (meth) acrylic oligomer, the acid value is determined according to the above formula for each monomer, and the obtained values are summed to determine the acid value. Ask for.

  When the pressure-sensitive adhesive composition of the present invention further contains a specific (meth) acrylic oligomer, the total acid value calculated by the above formula in the pressure-sensitive adhesive composition further improves the high-speed peelability after the heat treatment, In addition, from the viewpoint of imparting sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend, it is preferably 40 mgKOH / g or more and 90 mgKOH / g or less, more preferably 45 mgKOH / g or more and 80 mgKOH / g or less, and 50 mgKOH. / G or more and 75 mgKOH / g or less is still more preferable.

<(Meth) acrylic polymer>
The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention includes a structural unit derived from a monomer having a carboxy group, has an acid value of 40 mgKOH / g to 90 mgKOH / g, and a weight average molecular weight of 300,000. It is 1800000 or less.

The (meth) acrylic polymer is crosslinked by a crosslinking agent by including a structural unit derived from a monomer having a carboxy group.
In addition, the acid value of the (meth) acrylic polymer is 40 mgKOH / g or more and 90 mgKOH / g or less, so that the adhesive layer has excellent adhesive force so that it does not easily fall off from the adherend. High speed peelability can also be maintained.
Furthermore, the weight average molecular weight of the (meth) acrylic polymer is 300,000 or more, and it is easy to adjust the viscoelasticity of the pressure-sensitive adhesive layer. The period of time that can be stored after mixing (hereinafter also referred to as “pot life”) is long, and it is easy to produce an adhesive film.
The (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention may be only one type, or two or more types having different monomer compositions, weight average molecular weights, and the like.

  In the present specification, the “structural unit derived from a monomer having a carboxy group” means a structural unit formed by addition polymerization of a monomer having a carboxy group.

The kind of monomer having a carboxy group is not particularly limited.
Examples of the monomer having a carboxy group include (meth) acrylic acid, polyalkylene glycol (meth) acrylate having a carboxy group, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, 2- (meth) acryloyloxyethyl succinic acid, monohydroxyethyl (meth) acrylate maleate, monohydroxyethyl (meth) acrylate fumarate, monohydroxyethyl phthalate (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxy Examples include ethyl (meth) acrylate, (meth) acrylic acid dimer, and ω-carboxy-polycaprolactone mono (meth) acrylate. The monomer which has a carboxy group may be used individually by 1 type, and may use 2 or more types together.

  As alkylene glycol which comprises the polyalkylene glycol part of the polyalkylene glycol (meth) acrylate which has a carboxy group, the combination of ethylene glycol, propylene glycol, and ethylene glycol and propylene glycol is mentioned, for example.

  A monomer having a carboxy group imparts sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend, further improves the high-speed peelability after heat treatment, and lowers the dependency on the peel rate. From the viewpoint of suppression, (meth) acrylic acid, 2-methacryloyloxyethyl succinic acid, polyalkylene glycol (meth) acrylate having a carboxy group, ω-carboxy-polycaprolactone mono (meth) acrylate, and (meth) acrylic acid dimer It is preferable to include at least one selected from the group consisting of: (meth) acrylic acid, 2-methacryloyloxyethyl succinic acid, polyalkylene glycol (meth) acrylate having a carboxy group, and ω-carboxy-polycaprolactone mono Selected from the group consisting of (meth) acrylates More preferably, it contains at least one of the above.

  Furthermore, the (meth) acrylic polymer contained in the pressure-sensitive adhesive composition of the present invention preferably contains a structural unit derived from alkyl (meth) acrylate. Adhesive force can be easily adjusted because a (meth) acrylic-type polymer contains the structural unit derived from an alkyl (meth) acrylate.

  In the present specification, the “structural unit derived from alkyl (meth) acrylate” means a structural unit formed by addition polymerization of alkyl (meth) acrylate.

  When the (meth) acrylic polymer includes a structural unit derived from an alkyl (meth) acrylate, the alkyl (meth) acrylate is preferably an unsubstituted alkyl (meth) acrylate, and the type thereof is not particularly limited. The alkyl group of the alkyl (meth) acrylate may be linear, branched or cyclic. Moreover, the range of 1-18 is preferable and, as for carbon number of an alkyl group, the range of 1-12 is more preferable. When the carbon number of the alkyl group is within the above range, the adhesiveness and the adhesiveness to the substrate when used as an adhesive film are excellent.

Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, s-butyl (meth) acrylate, t -Butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (meth) acrylate, n-decyl (Meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
Alkyl (meth) acrylate may be used individually by 1 type, and may use 2 or more types together.

  Alkyl (meth) acrylate is 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate, i-nonyl acrylate, and lauryl from the viewpoint of compatibility between (meth) acrylic polymer and terpene phenolic tackifier. It is preferable to include at least one selected from the group consisting of methacrylates.

The ratio of the structural unit derived from the alkyl (meth) acrylate in the total structural unit of the (meth) acrylic polymer is excellent while providing the adhesive layer with sufficient adhesive strength so as not to easily fall off from the adherend. From the viewpoint of maintaining high-speed peelability, the content is preferably 50% by mass or more, more preferably 65% by mass or more, and still more preferably 80% by mass or more based on the entire structural unit.
In addition, the proportion of the structural unit derived from alkyl (meth) acrylate in the total structural units of the (meth) acrylic polymer is preferably 97% by mass or less based on the total structural units from the viewpoint of keeping contamination low. 96 mass% or less is more preferable, and 95 mass% or less is still more preferable.

The (meth) acrylic polymer preferably contains 50% by mass or more of a structural unit derived from a monomer having an acryloyl group with respect to all structural units (hereinafter also referred to as “acrylic monomer”). The (meth) acrylic polymer contains 50% by mass or more of structural units derived from the acrylic monomer with respect to all the structural units, so that the copolymerizability is improved and the carboxy group is more uniformly in the (meth) acrylic polymer. Since it can be distributed, unevenness of crosslinking is further suppressed, and contamination is further suppressed.
From the same viewpoint, the (meth) acrylic polymer preferably contains 60% by mass or more, more preferably 80% by mass or more, of structural units derived from acrylic monomers with respect to all the structural units.

  The (meth) acrylic polymer is a constituent unit derived from a monomer having a carboxy group and a constituent unit derived from an alkyl (meth) acrylate that is an arbitrary constituent unit within the range in which the effects of the present invention are exhibited. A structural unit (hereinafter, also referred to as “other structural unit”) may be included. In this case, the total ratio of the structural unit derived from the monomer having a carboxy group and the structural unit derived from the alkyl (meth) acrylate is 70% by mass or more based on the total structural unit of the (meth) acrylic polymer. Preferably, 75 mass% or more is more preferable, and 80 mass% or more is still more preferable.

The type of monomer constituting other structural units is not particularly limited.
Specific examples of monomers constituting other structural units include (meth) acrylates having a cyclic group represented by benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, and ethoxy. Alkoxyalkyl (meth) acrylates represented by ethyl (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, and aromatic monovinyl, acrylonitrile represented by vinyltoluene and Examples thereof include vinyl cyanide represented by methacrylonitrile, vinyl formate, vinyl acetate, vinyl propionate, vinyl esters represented by vinyl versatate, and various derivatives of these monomers. Moreover, the monomer which has functional groups other than a carboxy group, such as a hydroxyl group, a glycidyl group, an amide group or an N-substituted amide group, and a tertiary amino group, is mentioned.

  Specific examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6- Hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-hydroxybutyl (meta ) Acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, glycerin mono (Me ) Acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, and poly (ethylene glycol - include propylene glycol) mono (meth) acrylate.

  Specific examples of the monomer having a glycidyl group include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meth) allyl ether, and 3,4-epoxycyclohexyl (meth) allyl ether is mentioned.

  Specific examples of the monomer having an amide group or an N-substituted amide group include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N -Ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-tert-butylacrylamide, N-octylacrylamide, and diacetone acrylamide.

  Specific examples of the monomer having a tertiary amino group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropyl (meth) acrylamide.

The acid value of the (meth) acrylic polymer is preferably 42 mgKOH / g or more, more preferably 44 mgKOH / g or more, from the viewpoint of further improving the high-speed peelability.
The acid value of the (meth) acrylic polymer is 80 mgKOH / g from the viewpoint of maintaining excellent high-speed peelability while imparting sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend. The following is preferable, and 75 mgKOH / g or less is more preferable.

  The weight average molecular weight of the (meth) acrylic polymer is preferably 400,000 or more, more preferably 500,000 or more, from the viewpoint of keeping the contamination property low. In addition, the weight average molecular weight of the (meth) acrylic polymer is preferably 1400000 or less, and more preferably 1000000 or less, from the viewpoint of increasing the pot life.

  The dispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth) acrylic polymer is not particularly limited. For example, the dispersity (Mw / Mn) of the (meth) acrylic polymer is preferably in the range of 1 to 30 from the viewpoint of keeping the contamination property low.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the (meth) acrylic polymer are values measured by the following method. Specifically, the measurement is performed according to the following (1) to (3).
(1) A solution of a (meth) acrylic polymer is applied to a release paper and dried at 100 ° C. for 2 minutes to obtain a film-like (meth) acrylic polymer.
(2) Using the film-like (meth) acrylic polymer obtained in (1) and tetrahydrofuran, a sample solution having a solid content concentration of 0.2% by mass is obtained.
(3) Using gel permeation chromatography (GPC), the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth) acrylic polymer are measured as standard polystyrene equivalent values under the following conditions.

~conditions~
Measuring device: High-speed GPC (model number: HLC-8220 GPC, manufactured by Tosoh Corporation)
Detector: differential refractometer (RI) (built in HLC-8220, manufactured by Tosoh Corporation)
Column: 4 TSK-GEL GMHXL (manufactured by Tosoh Corporation) connected in series Column temperature: 40 ° C
Eluent: Tetrahydrofuran Sample concentration: 0.2% by mass
Injection volume: 100 μL
Flow rate: 0.6 mL / min

  The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably −50 ° C. or lower. When the Tg of the (meth) acrylic polymer is −50 ° C. or lower, the elasticity of the (meth) acrylic polymer is sufficiently low, so that an increase in adhesive force due to heat treatment can be suppressed, and high-speed peelability is more excellent. Further, when the Tg of the (meth) acrylic polymer is −50 ° C. or lower, the compatibility between the (meth) acrylic polymer and the terpene phenolic tackifier becomes high, so that the cross-linking structure with the tackifier becomes more uniform. It is formed. Thereby, the raise of the adhesive force by heat processing can be suppressed, and high-speed peelability is more excellent.

The Tg of the (meth) acrylic polymer is −50 by using a monomer having a Tg of −50 ° C. or less as a homopolymer as all or part of the monomer constituting the (meth) acrylic polymer. It can be adjusted to below ℃.
Specific examples of monomers having a Tg of −50 ° C. or less when homopolymers are butyl acrylate (−57 ° C.), 2-ethylhexyl acrylate (−76 ° C.), lauryl methacrylate (−65 ° C.), octyl Examples include acrylate (−65 ° C.), isooctyl acrylate (−58 ° C.), isononyl acrylate (−58 ° C.), and isomyristyl acrylate (−56 ° C.).

  Specific examples of monomers having a Tg exceeding −50 ° C. when homopolymers are methyl acrylate (5 ° C.), 4-hydroxybutyl acrylate (−39 ° C.), 2-hydroxyethyl acrylate (−15 ° C.), And acrylic acid (166 ° C.).

  “Tg when homopolymer” refers to Tg of a homopolymer produced by polymerizing the monomer alone. The Tg of the homopolymer was measured using a differential scanning calorimeter (DSC) (model number: EXSTAR6000, manufactured by Seiko Instruments Inc.) in a nitrogen stream, 10 mg of a measurement sample, and a heating rate of 10 ° C./min. The inflection point of the DSC curve obtained by measurement under the conditions is the Tg of the homopolymer.

  Tg of the (meth) acrylic polymer is a value obtained by converting the absolute temperature (K) obtained by calculation from the following formula into Celsius temperature (° C.).

In the formula, Tg1, Tg2,..., Tg (k-1), Tgk are glasses represented by absolute temperature (K) when each monomer constituting the (meth) acrylic polymer is a homopolymer. Represents the transition temperature. w1, w2,..., w (k-1), wk each represents a mass fraction of each monomer constituting the (meth) acrylic polymer, and w1 + w2 + ... + w (k-1) + wk = 1. It is.
The absolute temperature (K) can be converted to Celsius temperature (° C) by subtracting 273 from the absolute temperature (K), and the Celsius temperature (° C) can be converted to absolute temperature (K) by adding 273 to the Celsius temperature (° C). Can be converted to

<(Meth) acrylic oligomer>
The pressure-sensitive adhesive composition of the present invention further comprises a (meth) acrylic oligomer containing a structural unit derived from a monomer having a carboxy group, an acid value of 70 mgKOH / g or more, and a weight average molecular weight of 1,000 to 30,000. It is preferable to include.
When the pressure-sensitive adhesive composition of the present invention further contains a (meth) acrylic oligomer that satisfies the above requirements, an increase in pressure-sensitive adhesive force due to heat treatment can be further suppressed.

  When the pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic oligomer, the (meth) acrylic oligomer may be only one kind, and two or more kinds having different monomer compositions, weight average molecular weights, and the like. There may be.

The structural unit derived from the monomer having a carboxy group contained in the (meth) acrylic oligomer contributes to an improvement in high-speed peelability, a reduction in peel rate dependency, and a reduction in contamination.
The kind of monomer having a carboxy group is not particularly limited.
As a monomer which has a carboxy group, the monomer which has a carboxy group in the above-mentioned (meth) acrylic-type polymer can be mentioned, A preferable example is also the same.

The (meth) acrylic oligomer preferably includes a structural unit derived from an alkyl (meth) acrylate. The structural unit derived from alkyl (meth) acrylate contributes to the adjustment of adhesive force.
Examples of the alkyl (meth) acrylate constituting the structural unit derived from the alkyl (meth) acrylate include alkyl (meth) acrylates in the aforementioned (meth) acrylic polymers, and preferred examples are also the same.

  The proportion of the structural unit derived from alkyl (meth) acrylate in the total structural unit of the (meth) acrylic oligomer is excellent while giving the adhesive layer sufficient adhesive strength so that it does not easily fall off from the adherend. From the viewpoint of maintaining high-speed peelability, the content is preferably 40% by mass or more, more preferably 45% by mass or more, and still more preferably 50% by mass or more based on all the structural units. The proportion of the structural unit derived from the alkyl (meth) acrylate in the total structural units of the (meth) acrylic oligomer is preferably 95% by mass or less, based on the total structural units, from the viewpoint of lowering contamination. % Or less is more preferable, and 85% by mass or less is still more preferable.

The (meth) acrylic oligomer preferably contains 50% by mass or more of a structural unit derived from a monomer having an acryloyl group (acrylic monomer) with respect to all the structural units. By including 50% by mass or more of structural units derived from acrylic monomers with respect to all the structural units, the copolymerizability is improved and the carboxy group can be more uniformly distributed in the (meth) acrylic oligomer. Is further suppressed, and the pollution property can be kept lower.
The (meth) acrylic oligomer preferably contains 60% by mass or more, more preferably 70% by mass or more, of structural units derived from acrylic monomers with respect to all the structural units.

The (meth) acrylic oligomer is a constituent unit derived from a monomer having a carboxy group and a constituent unit derived from an alkyl (meth) acrylate that is an arbitrary constituent unit within the range in which the effects of the present invention are exhibited. A structural unit (other structural units) may be included. In this case, the total ratio of the structural unit derived from the monomer having a carboxy group in the total structural unit of the (meth) acrylic oligomer and the structural unit derived from the alkyl (meth) acrylate is based on the total structural unit. 50 mass% or more is preferable, 60 mass% or more is more preferable, and 70 mass% or more is still more preferable.
Examples of the monomer constituting other structural units include monomers constituting other structural units in the aforementioned (meth) acrylic polymers.

The acid value of the (meth) acrylic oligomer is sufficiently cross-linked with the (meth) acrylic polymer from the viewpoint of further improving the high-speed peelability, lowering the peel rate dependency, and lowering the contamination property. 70 mgKOH / g or more is preferable, 80 mgKOH / g or more is more preferable, and 90 mgKOH / g or more is more preferable.
Further, the acid value of the (meth) acrylic oligomer gives the adhesive layer sufficient adhesive strength that does not easily fall off from the adherend, while maintaining excellent high-speed peelability, and the adhesive layer From the viewpoint of reducing the haze, 200 mgKOH / g or less is preferable, 180 mgKOH / g or less is more preferable, and 160 mgKOH / g or less is more preferable.

  The weight average molecular weight of the (meth) acrylic oligomer is preferably 1000 or more, more preferably 4000 or more, and still more preferably 7000 or more, from the viewpoint of suppressing contamination. From the viewpoint of reducing the haze of the pressure-sensitive adhesive layer, the weight average molecular weight of the (meth) acrylic oligomer is preferably 30000 or less, more preferably 25000 or less, and still more preferably 20000 or less.

  The dispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth) acrylic oligomer is not particularly limited. For example, from the viewpoint of imparting sufficient adhesive strength to the pressure-sensitive adhesive layer so that it does not easily fall off from the adherend, while maintaining excellent high-speed peelability and keeping contamination low, (meth) acrylic The degree of oligomer dispersion (Mw / Mn) is preferably in the range of 1-30.

  The weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth) acrylic oligomer are the same as the method for measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth) acrylic polymer described above. Measured.

  The glass transition temperature (Tg) of the (meth) acrylic oligomer is preferably −20 ° C. or lower. When the Tg of the (meth) acrylic oligomer is −20 ° C. or lower, an increase in adhesive force due to heat treatment can be suppressed, and thus high-speed peelability is more excellent.

  The glass transition temperature (Tg) of the (meth) acrylic oligomer is calculated in the same manner as the calculation method of the glass transition temperature of the (meth) acrylic polymer described above.

The (meth) acrylic oligomer is 50 masses of structural units derived from monomers having a glass transition temperature (Tg) of −50 ° C. or lower when a homopolymer is used, with respect to all structural units of the (meth) acrylic oligomer. % Or more is preferable. For example, it is preferable to contain 50% by mass or more of 2-ethylhexyl acrylate having a Tg of −76 ° C. as a homopolymer with respect to all structural units of the (meth) acrylic oligomer. In this case, since the glass transition temperature of the (meth) acrylic oligomer is sufficiently low and the pressure-sensitive adhesive layer is more easily adapted to the adherend, the pressure-sensitive adhesive film is difficult to fall off during processing of the adherend.
Examples of the monomer having a Tg of −50 ° C. or less when the homopolymer is used include monomers having a Tg of −50 ° C. or less when the homopolymer in the (meth) acrylic polymer described above is used.

When the pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic oligomer, the ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass to 40 mass% is preferable, 3 mass%-30 mass% is more preferable, 3 mass%-20 mass% is still more preferable.
When the proportion of the (meth) acrylic oligomer is 1% by mass or more, the effect of adding the (meth) acrylic oligomer is sufficiently obtained. Since the raise of the adhesive force by heat processing can be suppressed as the ratio of a (meth) acrylic-type oligomer is 40 mass% or less, high-speed peelability is more excellent. In addition, since the (meth) acrylic polymer and the (meth) acrylic oligomer are sufficiently cross-linked, the (meth) acrylic oligomer hardly remains on the adherend, and the contamination property can be further reduced.

<Crosslinking agent>
The pressure-sensitive adhesive composition of the present invention contains a crosslinking agent. If the kind of crosslinking agent can bridge | crosslink the (meth) acrylic-type polymer which is contained in the adhesive composition of this invention, the below-mentioned terpene phenol-type tackifier, and the (meth) acrylic-type oligomer which is an arbitrary component, There is no particular limitation.
As the crosslinking agent, for example, an epoxy compound having an epoxy group and an isocyanate compound having an isocyanate group can be used.

  Examples of the epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether, 2,2-dibromo Neopentyl glycol diglycidyl A , Trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate, tris (glycidoxyethyl) isocyanurate, 1 , 3-bis (N, N-glycidylaminomethyl) cyclohexane, and N, N, N ′, N′-tetraglycidyl-m-xylylenediamine. These epoxy compounds may be used individually by 1 type, and may use 2 or more types together.

  Examples of the isocyanate compound include xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, aromatic polyisocyanate compounds represented by tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenation of the above-described aromatic polyisocyanate compound. Chain or cyclic aliphatic polyisocyanate compounds typified by products, biuret, dimer, trimer or pentamer of these polyisocyanate compounds, these polyisocyanate compounds and polyols such as trimethylolpropane Examples include adducts with compounds. These isocyanate compounds may be used individually by 1 type, and may use 2 or more types together.

When the pressure-sensitive adhesive composition of the present invention is used for applications in which transparency is important, the epoxy compound contains tris (glycidyl) isocyanurate, tris (glycidoxyethyl) isocyanurate, and 1,3-bis (N, At least one selected from the group consisting of (N-glycidylaminomethyl) cyclohexane is preferable, and 1,3-bis (N, N-glycidylaminomethyl) cyclohexane is more preferable. The isocyanate compound is a group consisting of a linear or cyclic aliphatic polyisocyanate compound and a biuret, dimer, trimer, pentamer or adduct of a linear or cyclic aliphatic polyisocyanate compound. And at least one selected from the group consisting of an isocyanate compound having an isocyanurate structure which is a trimer of hexamethylene diisocyanate, an adduct of hexamethylene diisocyanate, and a biuret of hexamethylene diisocyanate. More preferred. Since these isocyanate compounds do not have a structure derived from an aromatic ring, the pressure-sensitive adhesive layer after the heat treatment is hardly yellowed, and a pressure-sensitive adhesive film that is superior in transparency can be obtained.
Examples of uses that place importance on transparency include surface protection film uses for optical members.

A commercial item can be used for a crosslinking agent.
As a commercial item of the epoxy compound as a crosslinking agent, what is marketed with the brand name of "Tetrad-X" and "Tetrad-C" by Mitsubishi Gas Chemical Co., Ltd. can be used conveniently, for example.
As a commercial item of the isocyanate compound as a crosslinking agent, for example, “Coronate HX”, “Coronate HL-S”, “Coronate L”, “Coronate 2031”, “Coronate 2030”, “Coronate” manufactured by Nippon Polyurethane Co., Ltd. 2234 "," Coronate 2785 "," Aquanate 200 ", and" Aquanate 210 "," Sumijour N3300 "," Death Module N3400 ", and" Sumijoule N-75 "manufactured by Sumika Bayer Urethane Co., Ltd. "Duranate E-405-80T", "Duranate 24A-100" and "Duranate TSE-100" manufactured by Asahi Kasei Kogyo Co., Ltd., and "Takenate D-110N" manufactured by Mitsui Takeda Chemical Co., Ltd. "Takenate D-120N", "Takenate M-631N" and "MT- It can be suitably used those which are commercially available by the trade name of Leicester NP1200 ".

The content of the crosslinking agent is, for example, a carboxy group contained in the (meth) acrylic polymer [in the case where the pressure-sensitive adhesive composition of the present invention includes the (meth) acrylic oligomer described above, the (meth) acrylic polymer Functional group that contributes to cross-linking with respect to 1 equivalent of this carboxy group (or the total of carboxy groups) The amount (for example, epoxy group and isocyanate group) is preferably 0.5 equivalent or more and 2.0 equivalent or less.
When the equivalent of the functional group that contributes to crosslinking is 0.5 equivalent or more with respect to 1 equivalent of the carboxy group (or the total carboxy group), the pressure-sensitive adhesive layer becomes sufficiently hard, and the adhesive force increases due to heat treatment. Since it can suppress, high-speed peelability is more excellent. Moreover, since the quantity of the (meth) acrylic oligomer which is not cross-linked can be kept low, the contamination can be kept lower. When the equivalent of the functional group contributing to crosslinking is 2.0 equivalents or less with respect to 1 equivalent of carboxy groups (or total carboxy groups), the amount of the crosslinking agent not reacted with the (meth) acrylic polymer is low. Since it is suppressed, pollution property can be suppressed lower.
The content of the crosslinking agent is a carboxy group contained in the (meth) acrylic polymer [when the pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic oligomer described above, the (meth) acrylic polymer contains The total amount of the carboxy group and the carboxy group contained in the (meth) acrylic oligomer] is more preferably an amount in which the functional group contributing to crosslinking is 0.55 equivalents or more and 1.6 equivalents or less with respect to 1 equivalent. More preferably, the amount is from 6 equivalents to 1.2 equivalents.

<Terpene phenol tackifier>
The pressure-sensitive adhesive composition of the present invention contains a terpene phenolic tackifier.
A terpene phenol type tackifier may be used individually by 1 type, and may use 2 or more types together.

  In the present specification, “terpene phenolic tackifier” means a copolymer of terpenes and a phenol compound.

  Examples of terpene phenolic tackifiers include monocyclic monoterpenes represented by α-pinene, β-pinene, and dipentene (limonene), and phenolic compounds represented by phenol, cresol, and bisphenol A. A copolymer is mentioned.

  The terpene phenol type tackifier can use a commercial item. Examples of commercially available products include “YS Polystar U115”, “YS Polystar U130”, “YS Polystar T80”, “YS Polystar T100”, “YS Polystar T115”, “YS Polystar T130”, “YS Polystar T130”, “YS Polystar T130”, “YS Polyster TH130”, “YS Polystar T145”, “YS Polystar T160”, “YS Polystar S145”, “YS Polystar G125”, “YS Polystar G150”, “YS Polystar N125”, “YS Polystar K125”, and “YS Polystar K140 "and those commercially available under the trade names" Tamanol 803L "and" Tamanol 901 "manufactured by Arakawa Chemical Industries, Ltd. can be preferably used.

The content of the terpene phenol tackifier is a (meth) acrylic polymer [when the pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic oligomer described above, the (meth) acrylic polymer and (meth) Total with acrylic oligomer] is 0.1 to 5 parts by mass with respect to 100 parts by mass.
When the content of the terpene phenol tackifier is 0.1 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer (or the total of the acrylic polymer and the (meth) acrylic oligomer), the terpene phenolic The effect of adding tackifier is sufficiently obtained. When the content of the terpene phenolic tackifier is 5 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (or the total of the acrylic polymer and the (meth) acrylic oligomer), the original properties of the tackifier The effect of imparting adhesive strength, which is one of the above, is small, and an increase in adhesive strength due to heat treatment can be sufficiently suppressed, so that high-speed peelability is more excellent.
Further, from the same viewpoint, the content of the terpene phenol-based tackifier is preferably 0.3 parts by mass or more and 4 parts by mass or less, and more preferably 0.5 parts by mass or more and 3 parts by mass or less.

<Other ingredients>
Examples of other components that the pressure-sensitive adhesive composition of the present invention may contain in addition to the (meth) acrylic polymer, the crosslinking agent, the terpene phenolic tackifier, and the optional component (meth) acrylic oligomer include, for example, crosslinking Catalyst, chelating agent, solvent, weathering stabilizer, plasticizer, softener, dye, pigment, inorganic filler, antioxidant, polymer other than (meth) acrylic polymer, and oligomer other than (meth) acrylic oligomer Is mentioned.
In the pressure-sensitive adhesive composition of the present invention, since the functional group serving as a cross-linking point is a carboxy group, the cross-linking reaction can be completed without including a cross-linking catalyst.
When the pressure-sensitive adhesive composition contains these other components, the content of the other components can be appropriately set within the range in which the effect of the present invention is exhibited.

<Method for producing (meth) acrylic polymer and (meth) acrylic oligomer>
The production method of the (meth) acrylic polymer and (meth) acrylic oligomer used in the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, it can be produced by polymerizing monomers by a known polymerization method represented by solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, as the polymerization method, solution polymerization is preferable because the treatment process is relatively simple and can be performed in a short time.

  In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator and, if necessary, a chain transfer agent are generally charged in a polymerization tank and heated for several hours with stirring in a nitrogen stream or at the reflux temperature of the organic solvent. Let In this case, at least a part of the organic solvent, the monomer, the polymerization initiator, and / or the chain transfer agent may be sequentially added.

  Examples of the organic solvent used in the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha. Aliphatic or alicyclic typified by aromatic hydrocarbons, n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and turpentine oil Hydrocarbons, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, esters represented by methyl benzoate, acetone, methyl ethyl ketone, Methyl-i-butyl ketone, isophorone, cyclohexanone, and methylcyclohex Ketones represented by non, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and glycol ethers represented by diethylene glycol monobutyl ether, and methyl alcohol, Examples include alcohols represented by ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t-butyl alcohol. These organic solvents may be used individually by 1 type, and may use 2 or more types together.

  In the production of the (meth) acrylic polymer and the (meth) acrylic oligomer, it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction of esters and ketones. In particular, from the viewpoint of the solubility of the (meth) acrylic polymer and the (meth) acrylic oligomer, the ease of the polymerization reaction, etc., the organic solvent is at least one selected from the group consisting of ethyl acetate, methyl ethyl ketone, and acetone. Species are preferred.

As the polymerization initiator, organic peroxides, azo compounds and the like used in usual solution polymerization can be used.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxide. Carbonato, t-butylperoxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4 -Di-t-butylperoxycyclohexyl) butane, and 2,2 Bis (4,4-di -t- octyl peroxy cyclohexyl), and butane.
Examples of the azo compound include 2,2′-azobis-i-butylnitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-4-methoxy-2,4-dimethyl. Examples include valeronitrile, 1,1′-azobis-cyclohexane-1-carbonitrile, and 2,2′-azobis (methyl isobutyrate).

  In the production of the (meth) acrylic polymer and the (meth) acrylic oligomer, it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and an azobis polymerization initiator is particularly preferable.

The amount of the polymerization initiator used in the production of the (meth) acrylic polymer ranges from 0.01 parts by mass to 2 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic polymer. Is preferable, and the range of 0.1 parts by mass or more and 1 part by mass or less is more preferable.
In the production of the (meth) acrylic oligomer, the range of 0.1 to 20 parts by mass is preferable with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic oligomer, and 1 to 10 parts by mass. A range of less than or equal to part by mass is more preferred.

In the production of the (meth) acrylic polymer and the (meth) acrylic oligomer, a chain transfer agent can be used as necessary as long as the purpose and effect of the present invention are not impaired.
Examples of the chain transfer agent include cyanoacetic acid, cyanoacetic acid alkyl esters having 1 to 8 carbon atoms, bromoacetic acid, bromoacetic acid alkyl esters having 1 to 8 carbon atoms, α-methylstyrene, anthracene, phenanthrene, fluorene. And aromatic compounds typified by 9-phenylfluorene, aromatic nitro compounds typified by p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and p-nitrotoluene, Benzoquinone derivatives represented by benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives represented by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2- Tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloro Halogenated hydrocarbons typified by tan, tribromomethane, and 3-chloro-1-propene, aldehydes typified by chloral and furaldehyde, alkyl mercaptans having 1 to 18 carbon atoms, thiophenol and toluene mercaptan Specific examples include aromatic mercaptans, mercaptoacetic acid, alkyl esters having 1 to 10 carbon atoms of mercaptoacetic acid, hydroxyalkyl mercaptans having 1 to 12 carbon atoms, and terpenes represented by binene and terpinolene.

  The amount of the chain transfer agent used is, for example, in the range of 0.005 to 10.0 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the (meth) acrylic polymer and (meth) acrylic oligomer. Can be.

  As a polymerization temperature in producing a (meth) acrylic polymer and a (meth) acrylic oligomer, a range of 30 ° C. to 180 ° C. is preferable, a range of 50 ° C. to 150 ° C. is more preferable, and a temperature of 50 ° C. to 100 ° C. A range is still more preferable, and a range of 60 ° C to 90 ° C is particularly preferable.

<Adhesive film>
The pressure-sensitive adhesive film of the present invention includes a base material and a pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition of the present invention. That is, in the pressure-sensitive adhesive film of the present invention, a base material and a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention are laminated. The pressure-sensitive adhesive film of the present invention has a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention, so that the high-speed peelability after the heat treatment is excellent and the peel speed dependency is lowered.

  The material of the base material constituting the pressure-sensitive adhesive film of the present invention is not particularly limited. As a material of the base material, from the viewpoint of inspection and management of optical members by fluoroscopy, for example, polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, etc. Resin and acrylic resin are mentioned. Among these, as the base material, a polyester-based resin is preferable from the viewpoint of surface protection performance, and a polyethylene terephthalate resin is more preferable from the viewpoint of transparency and heat resistance.

  The thickness in particular of a base material is not restrict | limited, For example, it is 500 micrometers or less, the range of 5 micrometers-300 micrometers is preferable, and the range of 10 micrometers-200 micrometers is more preferable.

  The method for forming the pressure-sensitive adhesive layer provided on the substrate is not particularly limited, and a commonly used method can be adopted. Formation of the pressure-sensitive adhesive layer on the substrate is performed, for example, directly on the substrate that is the base film, with the pressure-sensitive adhesive composition of the present invention as it is or diluted with a solvent as necessary. It can be performed by a method of applying, drying and removing the solvent, curing and terminating the crosslinking reaction. As another method for forming the pressure-sensitive adhesive layer on the substrate, for example, the pressure-sensitive adhesive composition of the present invention is applied on a release sheet such as paper or polyester film that has been subjected to a release treatment with a silicone resin or the like. And drying to remove the solvent, curing and terminating the cross-linking reaction to form a pressure-sensitive adhesive layer, and then pressing the surface of the release sheet on which the pressure-sensitive adhesive layer is formed is brought into contact with the substrate and pressurized. A method of transferring the pressure-sensitive adhesive layer to the substrate side can be mentioned. If necessary, a release film may be laminated on the surface of the pressure-sensitive adhesive layer on the substrate thus prepared.

  Curing is performed, for example, in an environment of 23 ° C. and 50% RH for 4 to 14 days. By curing, the crosslinking reaction of the pressure-sensitive adhesive composition is completed, and a pressure-sensitive adhesive layer is formed.

  The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the type of adherend and the surface roughness of the adherend. Generally, the thickness of the pressure-sensitive adhesive layer is in the range of 1 μm to 100 μm, preferably in the range of 5 μm to 50 μm, and more preferably in the range of 15 μm to 30 μm.

  The pressure-sensitive adhesive film of the present invention has a sufficient pressure-sensitive adhesive strength so that the pressure-sensitive adhesive layer does not easily fall off from the adherend even after heat treatment (that is, a sufficiently large peel strength when peeling at low speed). It is preferable that the film can be easily peeled when peeled at a high speed (that is, a large peeling force is not needed when peeled at a high speed).

From such a viewpoint, the pressure-sensitive adhesive film of the present invention peels off the pressure-sensitive adhesive force (peeling force) to the adherend of the pressure-sensitive adhesive layer in a 180-degree peel test at 23 ° C. after heat treatment at 150 ° C. for 1 hour. At a speed of 10 m / min (high speed peeling), it is preferably 0.45 N / 25 mm or less, more preferably 0.4 N / 25 mm or less, and still more preferably 0.35 N / 25 mm or less.
The pressure-sensitive adhesive film can be easily peeled from the adherend when the pressure-sensitive adhesive force (peeling force) is 0.45 N / 25 mm or less during high-speed peeling. In particular, the peelability at a wide width is good.

  From the viewpoint of preventing damage to the adherend due to the adhesive film becoming difficult to peel off from the adherend due to heat treatment, the pressure-sensitive adhesive film of the present invention hardly changes the peel force even if the peel speed changes (that is, the peel speed). Preferably, the dependency is low.

From such a viewpoint, the pressure-sensitive adhesive film of the present invention preferably has a peel rate dependency rate (unit:%) of the pressure-sensitive adhesive layer in a 180-degree peel test at 23 ° C. after heat treatment at 150 ° C. for 1 hour. It is 170% or less, more preferably 155% or less, and still more preferably 140% or less.
When the peeling rate dependency rate is 170% or less, the adhesive film can be easily peeled from the adherend without depending on the peeling rate.
In this specification, the “peeling rate dependency rate” means a peeling rate of 10 m / min (high speed peeling) with respect to an adhesive force (hereinafter also referred to as “low speed peeling force”) at a peeling speed of 0.3 m / min (low speed peeling). It is a ratio of adhesive strength (hereinafter also referred to as “high-speed peeling force”), and is obtained by the following calculation formula.
Peeling speed dependency rate (%) = (high speed peeling force / low speed peeling force) × 100

  The gel fraction of the pressure-sensitive adhesive layer is preferably in the range of 90% by mass to 100% by mass, more preferably in the range of 93% by mass to 100% by mass, and 95% by mass to 100% by mass from the viewpoint of adhesive strength. The range of is more preferable.

In the present specification, the gel fraction of the pressure-sensitive adhesive layer is a ratio of a solvent-insoluble content measured using ethyl acetate as an extraction solvent. Specifically, the measurement is performed according to the following (1) to (4).
(1) About 0.25 g of the adhesive layer is affixed to a 250-mesh wire mesh (100 mm × 100 mm) whose mass has been accurately measured with a precision balance. Then, the wire mesh is folded five times to obtain a sample. Thereafter, the mass is accurately measured with a precision balance.
(2) The obtained sample is immersed in 80 ml of ethyl acetate for 3 days.
(3) A sample is taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. Thereafter, the mass is accurately measured with a precision balance.
(4) The gel fraction is calculated by the following formula.
Gel fraction (mass%) = (Z−X) / (Y−X) × 100
Where X is the mass (g) of the wire mesh, Y is the mass (g) before immersion of the wire mesh with the adhesive layer attached, and Z is the mass (g) of the wire mesh with the adhesive layer attached after drying. is there.

As an application of the pressure-sensitive adhesive film of the present invention, an application to be applied to an adherend to be heat-treated can be mentioned. Specifically, for example, it can be used as a surface protective film for an optical member, a surface protective film used in a manufacturing process of an electronic member, and a reinforcing film.
That is, the pressure-sensitive adhesive film of the present invention can be used as a heat-resistant pressure-sensitive adhesive film that protects or reinforces the surface of the adherend in the heat treatment step and can be easily peeled off after the heat treatment step.

The optical member as the adherend is, for example, a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a transparent conductive film (ITO film, ITO glass, etc.) ), And optical members used in liquid crystal display devices for design films and decorative films.
The optical member used for the liquid crystal display device may be heat-treated at, for example, 70 ° C. to 90 ° C. for the purpose of eliminating the disorder of the alignment of the liquid crystal when the liquid crystal display device is assembled.
A transparent conductive film, which is a kind of optical member used in a liquid crystal display device, is subjected to a heat treatment at, for example, 100 ° C. to 250 ° C. in a conductive substance crystallization step (ie, an annealing step). The surface to which the adhesive film of the transparent conductive film is attached may be the surface on which the transparent electrode is formed or the other surface.

Examples of the electronic member as the adherend include a flexible printed board and a rigid printed wiring board.
The flexible printed circuit board and the rigid printed circuit board are heat-treated at, for example, 100 ° C. to 250 ° C. in a hot press process.

The adherend to be heat-treated using the pressure-sensitive adhesive film of the present invention is preferably an adherend to be heat-treated at 100 to 250 ° C. The pressure-sensitive adhesive film of the present invention protects or reinforces the surface of an adherend in a heat treatment step at 100 ° C. to 250 ° C., and can be easily peeled off after the heat treatment step.
As an adherend heat-processed at 100 to 250 degreeC, a transparent conductive film, a flexible printed circuit board, and a rigid printed circuit board are mentioned, for example.

  The surface protective film is laminated on the surface of the optical member or the electronic member to protect the surface of the optical member or the electronic member from being contaminated or damaged. The optical member and the electronic member are subjected to heat treatment such as a crystallization process (that is, an annealing process), a high-temperature dry printing process, an etching process, and a pressing process while the surface protection film is laminated on the optical member and the electronic member. Is done. Thereafter, at the stage where surface protection is no longer necessary, it is peeled off from the optical member or electronic member.

  Since the pressure-sensitive adhesive film of the present invention uses a carboxy group as a cross-linking point, it can cause a cross-linking reaction without using a cross-linking catalyst.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

[Production of (meth) acrylic polymer]
[Production Example 1]
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a sequential dropping device, 31.7 parts by mass of ethyl acetate, 23.5 parts by mass of 2-ethylhexyl acrylate (2EHA) as an alkyl acrylate, a monomer having a carboxy group Acrylic acid (AA) 1.5 parts by mass, and 2,2′-azobis-i-butyronitrile (trade name: V-60, manufactured by Wako Pure Chemical Industries, Ltd.) 0.013 parts by mass as a polymerization initiator While stirring, the temperature in the reaction vessel was raised until reflux occurred. 20 minutes after the start of reflux, a solution prepared by dissolving 70.5 parts by mass of 2EHA, 4.5 parts by mass of AA, 0.038 parts by mass of V-60, and 9.2 parts by mass of ethyl acetate The reaction was completed over 120 minutes, and after completion of the addition, the reaction was completed over 150 minutes. After completion of the reaction, the solution was diluted with methyl ethyl ketone so that the solid content was 35% by mass to prepare a solution of a (meth) acrylic polymer. The term “solid content” means the amount of residue obtained by removing volatile components such as a solvent from a solution of a (meth) acrylic polymer.

Table 1 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), acid value (unit: mgKOH / g), and Tg (unit: ° C) of the obtained (meth) acrylic polymer. Shown in In Table 1, “weight average molecular weight” is simply expressed as “molecular weight”.
The weight average molecular weight (Mw) is measured by the method described above.
The acid value and Tg are calculated by the method described above. Specifically, the acid value of the (meth) acrylic polymer obtained in Production Example 1 was calculated as follows. In addition, the content rate of AA in all the monomers used for the (meth) acrylic-type polymer is 6.0 mass%, and the molecular weight of AA is 72.1. The number of carboxy groups contained in the AA1 molecule is 1.
Acid value (mgKOH / g) of the (meth) acrylic polymer obtained in Production Example 1 = {(6.0 / 100) ÷ 72.1} × 56.1 × 1000 × 1 = 46.7

[Production Examples 2 to 7]
In each of Production Examples 2 to 7, the composition of the monomer in Production Example 1 was changed as shown in Table 1, and by adjusting the amount of the solvent, the amount of the polymerization initiator, etc., as shown in Table 1, ( A (meth) acrylic polymer solution was prepared in the same manner as in Production Example 1 except that the weight average molecular weight of the (meth) acrylic polymer was adjusted.
Table 1 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), acid value (unit: mgKOH / g), and Tg (unit: ° C) of the obtained (meth) acrylic polymer. Shown in
The weight average molecular weight (Mw) is measured by the method described above.
The acid value and Tg are calculated by the method described above.

In Table 1, “MA” represents methyl acrylate, and “LMA” represents lauryl methacrylate.
The Tg described for each monomer in Table 1 is the Tg when the monomer is a homopolymer measured by the method described above.

[Production of (meth) acrylic oligomer]
[Production Example A]
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a sequential dropping device, 5.1 parts by mass of 2-ethylhexyl acrylate (2EHA) as alkyl acrylate and acrylic acid (AA) 0 as a monomer having a carboxy group .9 parts by mass, 19 parts by mass of toluene, 19 parts by mass of methyl ethyl ketone (MEK), and 2,2′-azobis (isobutyric acid) dimethyl (trade name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator ) 0.4 parts by mass was added and the temperature in the reaction vessel was increased while stirring until reflux occurred. Ten minutes after the start of reflux, 45.9 parts by mass of 2EHA, 8.1 parts by mass of AA, and 5.4 parts by mass of V-601 were dissolved in 8.8 parts by mass of MEK over 90 minutes. After completion of the dropwise addition, the reaction was completed over 230 minutes. After completion of the reaction, the solution was diluted with toluene so that the solid content was 35% by mass to prepare a (meth) acrylic oligomer solution. “Solid content” means the amount of residue obtained by removing volatile components such as a solvent from a solution of a (meth) acrylic oligomer.

Table 2 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), and acid value (unit: mg KOH / g) of the obtained (meth) acrylic oligomer. In Table 2, “weight average molecular weight” is simply expressed as “molecular weight”.
The weight average molecular weight (Mw) is measured by the method described above.
The acid value is calculated by the method described above. Specifically, the acid value of the (meth) acrylic oligomer obtained in Production Example A was calculated as follows. In addition, the content rate of AA in all the monomers used for the (meth) acrylic-type oligomer is 15.0 mass%, and the molecular weight of AA is 72.1.
Acid value (mgKOH / g) of the (meth) acrylic oligomer obtained in Production Example A = {(15.0 / 100) ÷ 72.1} × 56.1 × 1000 = 16.7

[Production Examples B to D]
In each of Production Examples B to D, the composition of the monomer in Production Example A was changed as shown in Table 2, and by adjusting the amount of the solvent, the amount of the polymerization initiator, and the like, as shown in Table 2, ( A (meth) acrylic oligomer solution was prepared in the same manner as in Production Example A except that the weight average molecular weight of the (meth) acrylic oligomer was adjusted.
Table 2 shows the monomer composition (unit: mass%), weight average molecular weight (Mw, unit: 10,000), and acid value (unit: mg KOH / g) of the obtained (meth) acrylic oligomer.
The weight average molecular weight (Mw) is measured by the method described above.
The acid value is calculated by the method described above.

“MA” in Table 2 represents methyl acrylate, and “LMA” represents lauryl methacrylate.
The Tg described for each monomer in Table 2 is the Tg when the monomer is a homopolymer measured by the method described above.

[Preparation of pressure-sensitive adhesive composition]
<Example 1>
95 parts by mass of the (meth) acrylic polymer solution prepared in Production Example 1 (solid content: 35% by mass) and 5% of the solution of the (meth) acrylic oligomer prepared in Production Example A (solid content: 35% by mass) 5 3.14 parts by mass (with epoxy compound, trade name: Tetrad-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 3.14 parts by mass (carboxy group and (meth) acrylic oligomer contained in (meth) acrylic polymer) The epoxy group contained in the epoxy compound is 1.0 equivalent with respect to 1 equivalent of the total carboxy group contained, and tackifier (trade name: YS Polystar TH130, terpene phenol tackifier, manufactured by Yasuhara Chemical Co., Ltd.) ) 1 part by mass was mixed and sufficiently stirred to obtain a pressure-sensitive adhesive composition of Example 1. Details of the composition and the like of the obtained pressure-sensitive adhesive composition are shown in Table 3.
The total acid values in Table 3 are calculated by the method described above. Specifically, the total acid value of the pressure-sensitive adhesive composition of Example 1 was calculated as follows.
Total acid value (mgKOH / g) of the pressure-sensitive adhesive composition of Example 1 = 46.7 × {95 / (95 + 5)} + 116.7 × {5 / (95 + 5)} = 50.2

[Preparation of test adhesive film]
Using the pressure-sensitive adhesive composition obtained above, a test pressure-sensitive adhesive film was produced as follows. On the polyethylene terephthalate (PET) film (trade name: Lumirror U35, thickness: 125 μm, manufactured by Toray Industries, Inc.), the pressure-sensitive adhesive composition was applied so that the coating amount after drying was 20 g / m ² . It dried for 60 seconds at 100 degreeC with the hot air circulation type dryer, and formed the layer of the adhesive composition. Next, the layer of the pressure-sensitive adhesive composition is in contact with a release film (trade name: Film Vina (registered trademark) 100E-0010NO23, manufactured by Fujimori Kogyo Co., Ltd.) whose surface is protected with a silicone-based release agent. A PET film was placed and bonded by pressing with a pressure nip roll. Thereafter, curing was carried out for 7 days in an environment of 23 ° C. and 50% RH to prepare a pressure-sensitive adhesive film for testing having a pressure-sensitive adhesive layer.
Table 3 shows the gel fraction of the obtained pressure-sensitive adhesive layer. The gel fraction is measured by the method described above.

(Measurement and evaluation)
1. High-speed peelability after heat treatment The test adhesive film prepared above was cut into a size of 25 mm × 150 mm, the release film was peeled off from the obtained test adhesive film piece, and a hard-coated PET film (product) Name: KB film G01S, manufactured by Kimoto Co., Ltd.) and bonded to the hard-coated surface, a 2 kg rubber roll was reciprocated once and pressure-bonded to obtain a test piece. The test piece was allowed to stand for 1 hour in an environment of 23 ° C. and 50% RH, and then heat-treated in an environment of 150 ° C. for 1 hour, and then left to stand in an environment of 23 ° C. and 50% RH for 1 hour.
About the test piece after standing, the adhesive force (unit: N / 25mm) in 180 degree peeling at the time of peeling the test adhesive film in the long side (150mm) direction is the conditions of peeling speed 10m / min (high speed peeling). The high-speed peelability after the heat treatment was evaluated according to the following evaluation criteria. The results are shown in Table 3.

-Evaluation criteria-
A: When it exceeds 0.2 N / 25 mm and is 0.35 N / 25 mm or less (high-speed peelability is very excellent)
B: More than 0.1N / 25mm and 0.2N / 25mm or less, or more than 0.35N / 25mm and 0.4N / 25mm or less (high-speed peelability is excellent)
C: When it exceeds 0.05 / 25 mm and is 0.1 N / 25 mm or less, or when it exceeds 0.4 N / 25 mm and is 0.45 N / 25 mm or less (high-speed peelability is slightly inferior, but within an allowable range)
D: 0.05 / 25 mm or less, or when exceeding 0.45 N / 25 mm (high speed peelability is inferior and out of tolerance)

2. Peeling speed dependence About the test piece produced by the same method as the test piece used for the evaluation of the high-speed peelability after the heat treatment, the adhesive force at 180 ° peeling when the test adhesive film is peeled in the long side (150 mm) direction (unit: N / 25 mm) was measured under the condition of a peeling speed of 0.3 m / min (low speed peeling). And the value of the adhesive force in the case of this low-speed peeling, and the above 1. By applying the following formula to the value of the adhesive strength in the case of high-speed peeling measured in the high-speed peelability evaluation after the heat treatment, the peel rate dependency rate (%) is calculated, and according to the following evaluation criteria, The peel rate dependency was evaluated. In addition, it shows that peeling rate dependence is so high that the value of peeling rate dependence rate is high.
The results are shown in Table 3.
Peeling speed dependency rate (%) = (high speed peeling force / low speed peeling force) × 100

-Evaluation criteria-
A: When the peel rate dependency rate is 140% or less (the peel rate dependency is very low)
B: When the peeling rate dependency ratio exceeds 140% and is 155% or less (the peeling rate dependency is low)
C: When the peel rate dependency rate exceeds 155% and is 170% or less (the peel rate dependency is slightly high but within an allowable range)
D: When the peeling rate dependency rate exceeds 170% (the peeling rate dependency is high and outside the allowable range)

3. Contamination property In the evaluation of the high-speed peelability after the heat treatment, 2 μL of pure water was dropped on the hard coat-treated surface of the hard-coated PET film after the test adhesive film was peeled off from the test piece at high speed. After 2 seconds, the contact angle (θ1) of water was measured using a contact angle measurement device (device name: Drop Master DM-701, manufactured by Kyowa Interface Science Co., Ltd.).
Absolute value (Δθ = | θ1) of the difference between the obtained value and the value of the contact angle of water (θ0 = 84 °) measured in advance on the hard-coated surface without the test adhesive film attached -Θ0 |) was calculated. Then, the calculated absolute value (Δθ) was used as a contamination index and evaluated according to the following criteria. The results are shown in Table 3.

A: When Δθ is 2.0 or less (contamination is very low)
B: When Δθ exceeds 2.0 and is 4.5 or less (contamination is low)
C: When Δθ exceeds 4.5 and is 7.5 or less (contamination is slightly high)
D: When Δθ exceeds 7.5 (highly contaminating)

<Examples 2 to 26 and Comparative Examples 1 to 7>
In each of Examples 2 to 26 and Comparative Examples 1 to 7, the type of (meth) acrylic polymer, (meth) acrylic oligomer, tackifier, and crosslinking agent in Example 1, (meth) acrylic polymer, and ( The blending ratio of the (meth) acrylic oligomer and the blending amount of the tackifier and the crosslinking agent are as shown in Table 3, and the blending amount of the crosslinking agent is the carboxy group and (meth) contained in the (meth) acrylic polymer. Functional group contributing to crosslinking contained in the crosslinking agent with respect to 1 equivalent of the total carboxy groups contained in the acrylic oligomer (for example, an epoxy group when the crosslinking agent is an epoxy compound, and an isocyanate compound) Is an isocyanate group.) Is the same as in Example 1 except that the equivalent is shown in Table 3. To obtain a Chakuzai composition.
Using the obtained pressure-sensitive adhesive composition, a test pressure-sensitive adhesive film was produced in the same manner as in Example 1. And about the produced adhesive film for a test, it carried out similarly to Example 1, and evaluated the high-speed peelability after heat processing, peeling rate dependence, and stain | pollution | contamination property. The results are shown in Table 3.

“-” In Table 3 means that there is no corresponding item.
The details of the name, type, and manufacturer of the tackifier in Table 3 are as follows.
U115: YS Polystar U115 (trade name), terpene phenol type, manufactured by Yashara Chemical Co., Ltd. T100: YS Polystar T100 (trade name), terpene phenol type, manufactured by Yashara Chemical Co., Ltd. TH130: YS Polystar TH130 (trade name), terpene phenol T160: YS Polystar T160 (trade name), terpene phenol, Yasuhara Chemical Co., Ltd. S145: YS Polystar S145 (trade name), terpene phenol, Yashara Chemical Co., Ltd. TR105: YS resin TR105 (Trade name), aromatic modified terpene, manufactured by Yasuhara Chemical Co., Ltd. SX100: YS Resin SX100 (product name), styrene, manufactured by Yasuhara Chemical Co., Ltd.

The trade name, type, and details of the manufacturer of the crosslinking agent in Table 3 are as follows.
Epoxy: TETRAD (registered trademark) -C (trade name), epoxy compound, manufactured by Mitsubishi Gas Chemical Co., Ltd. Isocyanate: Sumidur (registered trademark) N3300 (trade name), isocyanate compound, manufactured by Sumika Bayer Urethane Co., Ltd.

As shown in Table 3, the pressure-sensitive adhesive compositions of Examples 1 to 26 were all evaluated to be excellent in high-speed peelability after heat treatment and low in peel rate dependency.
The pressure-sensitive adhesive composition of Comparative Example 1 containing no terpene phenol tackifier was slightly inferior in high-speed peelability after heat treatment and highly dependent on the peel rate.
The pressure-sensitive adhesive composition of Comparative Example 2 including a tackifier other than the terpene phenol-based tackifier was inferior in the high-speed peelability after heat treatment and highly dependent on the peel rate.
The pressure-sensitive adhesive composition of Comparative Example 3 containing a tackifier other than the terpene phenol-based tackifier was slightly inferior in the high-speed peelability after the heat treatment and highly dependent on the peel rate.
The pressure-sensitive adhesive composition of Comparative Example 4 containing less than 0.1 part by mass of the terpene phenol-based tackifier with respect to 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer is subjected to heat treatment. The high-speed peelability was slightly inferior and the dependency on the peel rate was high.
The pressure-sensitive adhesive composition of Comparative Example 5 in which the content of the terpene phenolic tackifier with respect to 100 parts by mass in total of the (meth) acrylic polymer and the (meth) acrylic oligomer is higher than 5 parts by mass is high speed after the heat treatment. The peelability was inferior and the peel rate dependency was high.
The pressure-sensitive adhesive composition of Comparative Example 6 in which the acid value of the (meth) acrylic polymer was lower than 40 mgKOH / g was inferior in the high-speed peelability after the heat treatment and highly contaminated.
The pressure-sensitive adhesive composition of Comparative Example 7 in which the acid value of the (meth) acrylic polymer and the total acid value were higher than 90 mgKOH / g was inferior in the high-speed peelability after the heat treatment.

The pressure-sensitive adhesive composition of Example 1 containing both the (meth) acrylic polymer and the (meth) acrylic oligomer was heated in comparison with the pressure-sensitive adhesive composition of Example 25 not containing the (meth) acrylic oligomer. The high-speed peelability after the treatment was excellent, and the dependency on the peel rate was low.
In the pressure-sensitive adhesive composition (for example, Examples 1, 10, 11 etc.) having an acid value of (meth) acrylic oligomer of 70 mgKOH / g or more, a pressure-sensitive adhesive composition (for example, Example 9) lower than 70 mgKOH / g In comparison, the high-speed peelability after the heat treatment was excellent, the peeling speed dependency was lower, and the tendency for the contamination property to be lower was observed.

Claims (6)

A (meth) acrylic polymer containing a structural unit derived from a monomer having a carboxy group, having an acid value of 40 mgKOH / g or more and 90 mgKOH / g or less, and a weight average molecular weight of 300000 or more and 1800000 or less,
A (meth) acrylic oligomer containing a structural unit derived from a monomer having a carboxy group, having an acid value of 70 mgKOH / g or more, and a weight average molecular weight of 1,000 to 30,000,
A crosslinking agent;
Including terpene phenolic tackifier,
The ratio of the (meth) acrylic oligomer to the total mass of the (meth) acrylic polymer and the (meth) acrylic oligomer is 1% by mass or more and 40% by mass or less,
The (meth) Ri said terpene phenol tackifier der content of less than 5 parts by mass or more 0.1 part by weight of the fire with respect to the total 100 parts by mass of the acrylic polymer and the a (meth) acrylic oligomer,
Total acid value is calculated by the following formula is 40 mg KOH / g or more 90 mgKOH / g Ru der less pressure-sensitive adhesive composition.

The content of the crosslinking agent is such that the functional group contributing to crosslinking is 0 with respect to a total of 1 equivalent of the carboxy group contained in the (meth) acrylic polymer and the carboxy group contained in the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to claim 1 , wherein the pressure-sensitive adhesive composition is in an amount of from 5 equivalents to 2.0 equivalents. The (meth) acrylic oligomer has a structural unit derived from a monomer having a glass transition temperature (Tg) of −50 ° C. or less when a homopolymer is used, with respect to all structural units of the (meth) acrylic oligomer. The pressure-sensitive adhesive composition according to claim 1 or 2 , comprising 50% by mass or more. The pressure-sensitive adhesive composition according to any one of claims 1 to 3 , wherein a glass transition temperature (Tg) of the (meth) acrylic polymer is -50 ° C or lower. The pressure-sensitive adhesive composition according to any one of claims 1 to 4 , wherein the crosslinking agent is at least one selected from the group consisting of an epoxy compound and an isocyanate compound. An adhesive film provided with a base material and the adhesive layer which is provided on the said base material and originates in the adhesive composition of any one of Claims 1-5 .