WO2014192827A1

WO2014192827A1 - Adhesive composition, adhesive film, and article processing method

Info

Publication number: WO2014192827A1
Application number: PCT/JP2014/064171
Authority: WO
Inventors: 智也前田; 井ケ田　和博; 美仁小野; 琢美安田; 宮崎　英樹
Original assignee: 日本カーバイド工業株式会社
Priority date: 2013-05-29
Filing date: 2014-05-28
Publication date: 2014-12-04
Also published as: TW201504387A; KR20160013963A; KR102178180B1; JP6291492B2; JPWO2014192827A1; TWI616510B

Abstract

This adhesive composition comprises: an acrylic copolymer (A) that includes a structural unit (Ax) derived from a (meth)acrylic acid alkyl ester that does not have a hydroxyl group, and a structural unit (a) derived from an acrylate monomer that has a hydroxyl group; an acrylic copolymer (B) that includes a structural unit (Bx) derived from (meth)acrylic acid alkyl ester that does not have a hydroxyl group, and a structural unit (b) derived from a methacrylate monomer that has a hydroxyl group, said acrylic polymer (B) having a weight average molecular weight that is smaller than the weight average molecular weight of the acrylic copolymer (A); and an isocyanate compound. The total of the hydroxyl value (a) of the acrylic copolymer (A) and the hydroxyl value (b) of the acrylic copolymer (B) is in a range of 40 mg KOH/g to 90 mg KOH/g. The ratio of the hydroxyl value (a) to the hydroxyl value (b) is in the range of 0.5 to 7.0.

Description

Adhesive composition, adhesive film, and article processing method

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive film, and an article processing method.

When an article such as a metal plate, a coated steel plate, or a synthetic resin plate is processed or transported, an adhesive film is attached to protect the article surface from damage or dirt. 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 the pressure-sensitive adhesive film does not shift or fall off from the surface of the adherend while it is necessary to protect the surface of the adherend. It is required to have. Furthermore, when the pressure-sensitive adhesive layer is peeled from the surface of the adherend, at least part of the pressure-sensitive adhesive layer or at least part of the components constituting the pressure-sensitive adhesive layer remains. It is required to have a releasability (hereinafter also referred to as “easy releasability”) that can be easily peeled off from the adherend without causing contamination of the surface of the adherend due to, for example. Moreover, in the case of the processing method of the article | item which heat-processes in the state in which the adhesive film was affixed on the surface of the to-be-adhered body, the adhesive layer of an adhesive film is easy as above also after heat processing. It is required to have such a good peelability that can be peeled off. Furthermore, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film has a phenomenon called zipping that occurs due to uneven adhesion between the pressure-sensitive adhesive layer and the surface of the adherend when the pressure-sensitive adhesive film is peeled off from the surface of the adherend. That is also sought.

Japanese Patent Application Laid-Open No. 2007-327036 describes a pressure-sensitive adhesive composition containing a hydroxyl group-containing acrylic resin, an isocyanate-based crosslinking agent, and a low molecular weight non-reactive ester compound. The pressure-sensitive adhesive film having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a small increase in the pressure-sensitive adhesive force even after the heat treatment, and hardly contaminates the surface of the adherend after peeling. It is described.
Japanese Patent Application Laid-Open No. 2003-205567 describes a surface protective film having a pressure-sensitive adhesive layer crosslinked at high density as a surface protective film that can be easily peeled even after heat treatment.
Japanese Patent Application Laid-Open No. 2005-146151 describes a surface protective sheet having a pressure-sensitive adhesive layer obtained by crosslinking a crosslinkable composition containing two kinds of acrylic polymers having different glass transition temperatures and a crosslinking agent. . The adherend protected by this surface protection sheet does not float or peel off between the pressure-sensitive adhesive layer and the adherend even when heat-treated, and has good high-speed peelability during peeling. It is described that the surface of the subsequent adherend is not contaminated.

However, in a surface protective sheet having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a low molecular weight non-reactive ester compound as described in JP-A-2007-327036, the surface protective sheet is used after heat treatment. When peeled off, contamination of the surface of the adherend may not be sufficiently suppressed.
As described in JP-A-2003-205567, the crosslinking density of the pressure-sensitive adhesive layer is increased, or as described in JP-A-2005-146151, the glass transition to a crosslinkable composition used for forming the pressure-sensitive adhesive layer is performed. Even after containing two kinds of resins having different temperatures, it is possible to achieve both the property that the surface protective sheet can be easily peeled and the property that the surface of the adherend is less contaminated after the peeling. May not be enough.

The present invention has been made in view of the above, and is a pressure-sensitive adhesive composition that is excellent in releasability from the surface of an adherend even after heat treatment, and in which contamination of the surface of the adherend after peeling is suppressed, and It is an object to provide an adhesive film.
Furthermore, the present invention provides a method for treating an article in which the adhesive film can be easily peeled off from the surface of the adherend even after the heat treatment, and contamination of the surface of the adherend after peeling is suppressed. This is the issue.

Specific means for achieving the above object are as follows.
<1> Acrylic copolymer A containing structural unit Ax derived from (meth) acrylic acid alkyl ester having no hydroxyl group, and structural unit a derived from an acrylate monomer having a hydroxyl group, and having no hydroxyl group (meth) An acrylic copolymer comprising a structural unit Bx derived from an alkyl acrylate ester and a structural unit b derived from a methacrylate monomer having a hydroxyl group, and having a weight average molecular weight smaller than the weight average molecular weight of the acrylic copolymer A B and an isocyanate compound, the total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is in the range of 40 mgKOH / g to 90 mgKOH / g, The ratio of a to the hydroxyl value b (hydroxyl value a / hydroxyl value b) is in the range of 0.5 to 7.0. An adhesive composition.

<2> The ratio of the weight average molecular weight of the acrylic copolymer B to the weight average molecular weight of the mixture of the acrylic copolymer A and the acrylic copolymer B is 0.1 to 0.5. The pressure-sensitive adhesive composition according to <1>, which is a range.

<3> The pressure-sensitive adhesive composition according to <1> or <2>, wherein the ratio of the hydroxyl value a to the hydroxyl value b is in the range of 0.5 to 2.0.

<4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the content of the structural unit a in the acrylic copolymer A is 30% by mass or less.
<5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, wherein the content of the structural unit b in the acrylic copolymer B with respect to all the structural units is 10% by mass or more.

<6> The content of the isocyanate compound is 0.4 to 2.2 equivalents relative to the amount of hydroxyl groups contained in the acrylic copolymer A and the acrylic copolymer B. <1> The pressure-sensitive adhesive composition according to any one of to <5>.

<7> The <1> to <6>, wherein the acrylic copolymer A and the acrylic copolymer B each have a glass transition temperature (Tg) of −40 ° C. or lower. Adhesive composition.

<8> The acrylic copolymer A has a weight average molecular weight in the range of 400,000 to 1,500,000, and the acrylic copolymer B has a weight average molecular weight in the range of 100,000 to 500,000. <1> The pressure-sensitive adhesive composition according to any one of to <7>.

<9> A pressure-sensitive adhesive film comprising a base material and a pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition according to any one of <1> to <8> provided on the base material.
<10> On the surface of the article, the pressure-sensitive adhesive film according to <9> is attached so that the pressure-sensitive adhesive layer and the surface are in contact with each other, and the pressure-sensitive adhesive film is attached in the step of attaching. A method for treating an article, comprising: a heat treatment step for heating the attached article; and a peeling step for peeling the adhesive film from a surface of the article heated in the heat treatment step.

According to the present invention, it is possible to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film that are excellent in releasability from the surface of an adherend even after heat treatment and in which contamination of the surface of the adherend after peeling is suppressed. it can.
Furthermore, according to the present invention, there is provided a method for treating an article in which an adhesive film can be easily peeled off from the surface of an adherend even after heat treatment, and contamination of the surface of the adherend after peeling is suppressed. Provided.

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 the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
The amount of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.
The term “(meth) acrylic acid alkyl ester” is meant to include both “acrylic acid alkyl esters” and “methacrylic acid alkyl esters”. Similarly, the term “(meth) acrylate” is meant to encompass both “acrylate” and “methacrylate”, and the term “(meth) acrylamide” refers to “acrylamide” and “methacrylamide”. Means that both of them are included.
A constituent unit in an acrylic copolymer is “main component” means that the content ratio of the constituent unit on a mass basis is the largest among all the constituent units of the acrylic copolymer. In an embodiment of the present invention, the content of the structural unit that is the main component of the acrylic copolymer is 50% by mass or more.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer A containing a structural unit Ax derived from a (meth) acrylic acid alkyl ester having no hydroxyl group and a structural unit a derived from an acrylate monomer having a hydroxyl group, and a hydroxyl group. An acrylic copolymer B containing a structural unit Bx derived from a non- (meth) acrylic acid alkyl ester and a structural unit b derived from a methacrylate monomer having a hydroxyl group, and having a weight average molecular weight smaller than that of the acrylic copolymer A; The total of hydroxyl value a of acrylic copolymer A and hydroxyl value b of acrylic copolymer B is 40 mgKOH / g to 90 mgKOH / g, and The ratio (hydroxyl value a / hydroxyl value b) is 0.5 to 7.0. By satisfy | filling the said requirements, the adhesive composition of this invention is excellent in the peelability from the to-be-adhered body after heat processing, and the contamination of an to-be-adhered body is suppressed.

The present inventors consider the reason why the pressure-sensitive adhesive composition of the present invention is excellent in peelability from the adherend after heat treatment and the contamination of the adherend is suppressed as follows. That is, the pressure-sensitive adhesive composition of the present invention contains two types of acrylic copolymers having different crosslinking reactivity, acrylic copolymer A and acrylic copolymer B. For this reason, when the pressure-sensitive adhesive composition is crosslinked, a portion having a high crosslinking density derived from the structural unit a in the acrylic copolymer A and a crosslinking density derived from the structural unit b in the acrylic copolymer B are obtained. Low part occurs. A portion having a high cross-linking density and a portion having a low cross-linking density are entangled in the cross-linked pressure-sensitive adhesive composition, so that the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has an appropriate pressure-sensitive adhesive force. Since it becomes difficult to change the quality during the treatment, it is considered that the peelability from the adherend after the heat treatment is excellent, and contamination of the adherend is suppressed.

In the pressure-sensitive adhesive composition of the present invention, the total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is 40 mgKOH / g to 90 mgKOH / g. When the total of the hydroxyl value a and the hydroxyl value b is less than 40 mgKOH / g, the crosslinking reaction becomes insufficient, and the increase in the adhesive force of the pressure-sensitive adhesive composition cannot be sufficiently suppressed, and the contamination may be deteriorated. If the sum of the hydroxyl value a and the hydroxyl value b exceeds 90 mgKOH / g, the crosslinking reaction may proceed excessively and the required adhesive strength may not be maintained. Moreover, the viscosity of the pressure-sensitive adhesive composition tends to increase, and the storage stability may deteriorate.

The total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is preferably 45 mgKOH / g or more, more preferably 52 mgKOH / g or more, and 56 mgKOH / g or more. More preferably it is. The total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is preferably 74 mgKOH / g or less, more preferably 70 mgKOH / g or less, and 65 mgKOH / g. g or less is more preferable, and 61 mgKOH / g or less is still more preferable.

In the pressure-sensitive adhesive composition of the present invention, the ratio of the hydroxyl value a of the acrylic copolymer A to the hydroxyl value b of the acrylic copolymer B (hydroxyl value a / hydroxyl value b) is 0.5 to 7.0. is there. When the value of hydroxyl value a / hydroxyl value b is less than 0.5, the ratio of the portion having a low crosslink density to the portion having a high crosslink density is too large, and the contamination may be deteriorated. When the value of hydroxyl value a / hydroxyl value b exceeds 7.0, the ratio of the portion with low crosslink density to the portion with high crosslink density is too small, and the adhesive strength increases after heat treatment, and the peelability deteriorates. There is.

The ratio of the hydroxyl value a of the acrylic copolymer A to the hydroxyl value b of the acrylic copolymer B (hydroxyl value a / hydroxyl value b) is preferably 0.6 or more, and 0.7 or more. Is more preferable and 0.8 or more is more preferable. The ratio of the hydroxyl value a of the acrylic copolymer A to the hydroxyl value b of the acrylic copolymer B (hydroxyl value a / hydroxyl value b) is preferably 2.0 or less, and 1.7 or less. Is more preferably 1.4 or less, and further preferably 1.0 or less.

When the ratio of the hydroxyl value a of the acrylic copolymer A to the hydroxyl value b of the acrylic copolymer B (hydroxyl value a / hydroxyl value b) is 2.0 or less, zipping that occurs during peeling is suppressed. The
When the ratio is 2.0 or less, a portion having a high crosslinking density derived from the structural unit a in the acrylic copolymer A and a crosslinking density derived from the structural unit b in the acrylic copolymer B are obtained. A low part will disperse | distribute more uniformly in an adhesive composition. Therefore, since the difference in strength depending on the location of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition becomes small, it is thought that zipping that occurs at the time of peeling is suppressed. .

In the present invention, the hydroxyl value “a” of the acrylic copolymer A and the hydroxyl value “b” of the acrylic copolymer B are determined by the following calculation formulas, respectively.

Hydroxyl value a (mgKOH / g) = {(A1 / 100) ÷ B1} × C1 × 1000
A1 = content (% by mass) of a monomer having a hydroxyl group used in the acrylic copolymer A in all monomers used in the acrylic copolymer A and the acrylic copolymer B
B1 = Molecular weight of the monomer having a hydroxyl group used in the acrylic copolymer A C1 = Molecular weight of KOH

Hydroxyl value b (mg KOH / g) = {(A2 / 100) ÷ B2} × C2 × 1000
A2 = content (% by mass) of the monomer having a hydroxyl group used in the acrylic copolymer B in all monomers used in the acrylic copolymer A and the acrylic copolymer B
B2 = Molecular weight of the monomer having a hydroxyl group used for the acrylic copolymer B C2 = Molecular weight of KOH

Used when at least one of the acrylic copolymer A and the acrylic copolymer B is a mixture of two or more kinds of copolymers, or at least one of the acrylic copolymer A and the acrylic copolymer B. When there are two or more monomers having a hydroxyl group, the hydroxyl value is obtained according to the above formula for each acrylic copolymer or monomer, and the obtained values are summed to obtain a hydroxyl value a or a hydroxyl value. b is obtained.

(Acrylic copolymer A)
The pressure-sensitive adhesive composition of the present invention comprises at least an acrylic copolymer A comprising a structural unit Ax derived from a (meth) acrylic acid alkyl ester having no hydroxyl group and a structural unit a derived from an acrylate monomer having a hydroxyl group. Contains one species. In the present specification, the “structural unit derived from an acrylate monomer having a hydroxyl group” means a repeating unit formed by addition polymerization of an acrylate monomer having a hydroxyl group.

The content of the structural unit a contained in the acrylic copolymer A is 7% by mass or more with respect to all the structural units of the acrylic copolymer A (that is, with respect to the mass of the acrylic copolymer A). It is preferable that When the content of the structural unit a contained in the acrylic copolymer A is 7% by mass or more, the crosslinking reaction proceeds sufficiently, and the cross-linked pressure-sensitive adhesive composition has a cross-linking density derived from the structural unit a. There is a tendency that a portion having high and low tackiness is sufficiently formed. The content of the structural unit a contained in the acrylic copolymer A is more preferably 9% by mass or more, and further preferably 11% by mass or more.

The content rate of the structural unit a contained in the acrylic copolymer A is 30 mass% or less with respect to all the structural units of the acrylic copolymer A (that is, with respect to the mass of the acrylic copolymer A). It is preferable that When the content of the structural unit a contained in the acrylic copolymer A is 30% by mass or less, excessive progress of the crosslinking reaction is suppressed, and in the crosslinked pressure-sensitive adhesive composition, crosslinking derived from the structural unit a. There is a tendency that a portion having high density and low adhesiveness is appropriately formed. Moreover, it can suppress effectively that a viscosity raises during preservation | save of an adhesive composition. The content of the structural unit a contained in the acrylic copolymer A is more preferably 25% by mass or less, further preferably 20% by mass or less, and further preferably 18% by mass or less.

The structure of the acrylate monomer having a hydroxyl group used for forming the acrylic copolymer A is not particularly limited. For example, alkyl acrylate having a hydroxyl group, polyalkylene glycol acrylate having a hydroxyl group, and the like can be given.

The alkyl moiety of the alkyl acrylate having a hydroxyl group may be linear, branched or cyclic. The number of carbon atoms in the alkyl moiety of the alkyl acrylate having a hydroxyl group is preferably in the range of 1-12. When the carbon number of the alkyl moiety is within the above range, it is advantageous in terms of adhesiveness and adhesiveness to the substrate when used as an adhesive film. The number of carbon atoms in the alkyl moiety of the alkyl acrylate having a hydroxyl group is more preferably 2 to 6, and further preferably 2 to 4.

Examples of the alkylene glycol constituting the polyalkylene glycol moiety of the polyalkylene glycol acrylate having a hydroxyl group include ethylene glycol, propylene glycol, a combination of ethylene glycol and propylene glycol.

Specific examples of the acrylate monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, 10-hydroxydecyl acrylate, 12-hydroxy Lauryl acrylate, 3-methyl-3-hydroxybutyl acrylate, 1,1-dimethyl-3-butyl acrylate, 1,3-dimethyl-3-hydroxybutyl acrylate, 2,2,4-trimethyl-3-hydroxypentyl acrylate, 2-ethyl-3-hydroxyhexyl acrylate, glycerin monoacrylate, polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, poly Ethylene glycol - propylene glycol) monoacrylate, and the like. The acrylate monomer having a hydroxyl group may be used alone or in combination of two or more.

From the viewpoint of obtaining an appropriate adhesive force to the adherend and good peelability, the acrylate monomer having a hydroxyl group is preferably an alkyl acrylate having a hydroxyl group, such as 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, 6- More preferably, it contains at least one selected from the group consisting of hydroxyhexyl acrylate, 10-hydroxydecyl acrylate, and 12-hydroxy lauryl acrylate, and includes 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and 6-hydroxyhexyl acrylate. More preferably, at least one selected from the group consisting of:

As the alkyl acrylate having a hydroxyl group, at least one of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate is particularly preferable. These are particularly good in compatibility and copolymerization with other monomers when synthesizing the acrylic copolymer A, and the crosslinking reaction with the crosslinking agent when a crosslinking agent is used in combination is particularly good. It is good.

The acrylic copolymer A contains a structural unit Ax derived from a (meth) acrylic acid alkyl ester having no hydroxyl group, preferably as a main component.

The ratio of the structural unit Ax to the total structural unit of the acrylic copolymer A is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 85% by mass or more.

The alkyl moiety of the (meth) acrylic acid alkyl ester having no hydroxyl group may be either linear or branched, and preferably has a carbon number in the range of 1-18. When the carbon number of the alkyl moiety is within the above range, it is advantageous in terms of adhesiveness and adhesiveness to the substrate when used as an adhesive film. The number of carbon atoms in the alkyl moiety is more preferably in the range of 1-12. The alkyl moiety of the (meth) acrylic acid alkyl ester having no hydroxyl group is preferably unsubstituted.

Specific examples of (meth) acrylic acid alkyl esters having no hydroxyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and 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, and the like. The (meth) acrylic acid alkyl ester having no hydroxyl group may be used alone or in combination of two or more.

From the viewpoint of expressing appropriate adhesive strength to the adherend, the (meth) acrylic acid alkyl ester having no hydroxyl group is composed of 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate and lauryl (meth) acrylate. It is preferable to include at least one selected from the group.

The acrylic copolymer A is a structural unit y derived from a monomer having a hydroxyl group other than the structural unit a in addition to the structural unit a derived from an acrylate monomer having a hydroxyl group, for example, a structural unit derived from a methacrylate monomer having a hydroxyl group. Etc. may be included. Specific examples of the methacrylate monomer having a hydroxyl group described in the section of the acrylic copolymer B described later can be given.

When the acrylic copolymer A contains the structural unit y, the content of the structural unit y with respect to the total mass of the structural units in the acrylic copolymer A is preferably 7% by mass or less. By making the content rate of the structural unit y with respect to the total mass of the structural unit in the acrylic copolymer A 7 mass% or less, the contamination with respect to a to-be-adhered body can be suppressed. The content of the structural unit y relative to the total mass of the structural units in the acrylic copolymer A is more preferably 5% by mass or less, and further preferably 3% by mass or less.

In addition to the structural unit Ax derived from the (meth) acrylic acid alkyl ester having no hydroxyl group, the structural unit a derived from the acrylate monomer having a hydroxyl group, and the structural unit y included as desired, the acrylic copolymer A includes: The structural unit c derived from other monomers other than these may be included as needed. When the acryl-type copolymer A contains the structural unit c, the monomer used for formation of the structural unit c may be 1 type, or may be 2 or more types.

Examples of the monomer used for forming the structural unit c include monomers other than (meth) acrylic acid alkyl ester having no hydroxyl group, monomers having a functional group other than hydroxyl group, and the like.

Specific examples of monomers other than (meth) acrylic acid alkyl ester having no hydroxyl group include cyclic groups such as cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, and phenoxyethyl (meth) acrylate. (Meth) acrylic acid ester monomer having methacrylic acid (alkoxyalkyl) monomer such as methoxyethyl (meth) acrylate, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloro Aromatic monovinyl monomers such as methylstyrene and vinyltoluene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate, these Various types of monomers , And the like conductor.

Specific examples of the monomer having a functional group other than a hydroxyl group include a monomer having a carboxy group, a monomer having a glycidyl group, a monomer having an amide group or an N-substituted amide group, and a tertiary amino group. And the like.

Specific examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, succinic acid monohydroxyethylate, maleic acid Monohydroxyethyl (meth) acrylate, monohydroxyethyl fumarate (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic acid dimer, ω-carboxy-polycaprolactone mono (meth) acrylate and the like.

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, 3 , 4-epoxycyclohexyl (meth) allyl ether and the like.

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-butyl acrylamide, N-octyl acrylamide, diacetone acrylamide and the like.

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

When the acrylic copolymer A includes the structural unit c, the content of the structural unit c is preferably 10% by mass or less with respect to the total mass of the structural units in the acrylic copolymer A, and is 5 masses. % Or less is more preferable.

The weight average molecular weight (Mw) of the acrylic copolymer A is preferably in the range of 400,000 to 1,500,000, more preferably in the range of 500,000 to 1.3 million, and in the range of 600,000 to 1,200,000. More preferably it is. When the Mw of the acrylic copolymer A is 400,000 or more, contamination of the adherend can be further suppressed. Moreover, the adhesive force at the time of re-peeling does not become too large that Mw of acrylic copolymer A is 1.5 million or less, and the pressure-sensitive adhesive film can be peeled more easily.

The degree of dispersion (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic copolymer A is not particularly limited, but it is tacky and contamination to the adherend. From the viewpoint of suppression, it is preferably in the range of 1-30.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer A are values measured by the following method. Specifically, it is measured according to the following (1) to (3).
(1) A solution of acrylic copolymer A is applied to release paper and dried at 100 ° C. for 2 minutes to obtain film-like acrylic copolymer A.
(2) A sample solution having a solid content concentration of 0.2% by mass is obtained using the film-like acrylic copolymer A obtained in (1) and tetrahydrofuran.
(3) Weight average molecular weight (Mw) and number average molecular weight (Mn) of acrylic copolymer A under the following conditions as standard polystyrene conversion values using gel permeation chromatography (GPC) under the following conditions: ).
-conditions-
・ GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: 4 TSK-GEL GMHXL used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.6 mL / min Column temperature: 40 ° C

The glass transition temperature (Tg) of the acrylic copolymer A is preferably −40 ° C. or lower. When the Tg of the acrylic copolymer A is −40 ° C. or lower, the flowability of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition is excellent, and the familiarity to the adherend is good. The Tg of the acrylic copolymer A is more preferably −60 ° C. or less, and further preferably −70 ° C. or less.

Tg of the acrylic copolymer A is a value obtained by converting the absolute temperature (K) obtained by calculation from the following formula 1 into Celsius temperature (° C.).
1 / Tg = w1 / Tg1 + w2 / Tg2 + ... + w (k-1) / Tg (k-1) + wk / Tgk (Formula 1)
In Formula 1, Tg1, Tg2,..., Tg (k-1), and Tgk represent the glass transition temperature (K) of the homopolymer of each monomer constituting the acrylic copolymer A, respectively. w1, w2,..., w (k-1), wk respectively represent the mass fraction of each monomer constituting the acrylic copolymer A, and w1 + w2 + ... + w (k-1) + wk = 1.

The content of the acrylic copolymer A in the pressure-sensitive adhesive composition is in the range of 40% by mass to 90% by mass with respect to the total mass of the pressure-sensitive adhesive composition from the viewpoint of adhesion and suppression of contamination on the adherend. Preferably, it is in the range of 45% by mass to 85% by mass, and more preferably in the range of 45% by mass to 80% by mass.

(Acrylic copolymer B)
The pressure-sensitive adhesive composition of the present invention comprises at least an acrylic copolymer B containing a structural unit Bx derived from a (meth) acrylic acid alkyl ester having no hydroxyl group and a structural unit b derived from a methacrylate monomer having a hydroxyl group. Contains one species. In the present specification, the “structural unit derived from a methacrylate monomer having a hydroxyl group” means a repeating unit formed by addition polymerization of a methacrylate monomer having a hydroxyl group.

The content rate of the structural unit b contained in the acrylic copolymer B is 10 mass% or more with respect to all the structural units of the acrylic copolymer B (that is, with respect to the mass of the acrylic copolymer B). It is preferable that It exists in the tendency which can suppress that the adhesive force after heat processing rises too much that the content rate of the structural unit b contained in the acryl-type copolymer B is 10 mass% or more. As for the content rate of the structural unit b contained in the acryl-type copolymer B, it is more preferable that it is 14 mass% or more, and it is further more preferable that it is 17 mass% or more.

It is preferable that the content rate of the structural unit b contained in the acrylic copolymer B is 25 mass% or less with respect to all the structural units of the acrylic copolymer B. When the content of the structural unit b contained in the acrylic copolymer B is 25% by mass or less, contamination of the adherend tends to be suppressed. As for the content rate of the structural unit b contained in the acryl-type copolymer B, it is more preferable that it is 22 mass% or less, and it is further more preferable that it is 20 mass% or less.

The structure of the methacrylate monomer having a hydroxyl group used for forming the acrylic copolymer B is not particularly limited. Examples thereof include alkyl methacrylate having a hydroxyl group, polyalkylene glycol methacrylate having a hydroxyl group, and the like.

The alkyl moiety of the alkyl methacrylate having a hydroxyl group may be linear, branched or cyclic. The number of carbon atoms in the alkyl moiety of the alkyl methacrylate having a hydroxyl group is preferably in the range of 1-12. When the carbon number of the alkyl moiety is within the above range, it is advantageous in terms of adhesiveness and adhesiveness to the substrate when used as an adhesive film. The number of carbon atoms in the alkyl moiety of the alkyl methacrylate having a hydroxyl group is more preferably 2 to 6, and further preferably 2 to 4.

Examples of the alkylene glycol constituting the polyalkylene glycol moiety of the polyalkylene glycol methacrylate having a hydroxyl group include ethylene glycol, propylene glycol, a combination of ethylene glycol and propylene glycol.

Specific examples of the methacrylate monomer having a hydroxyl group include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 10-hydroxydecyl methacrylate, and 12-hydroxy. Lauryl methacrylate, 3-methyl-3-hydroxybutyl methacrylate, 1,1-dimethyl-3-butyl methacrylate, 1,3-dimethyl-3-hydroxybutyl methacrylate, 2,2,4-trimethyl-3-hydroxypentyl methacrylate, 2-ethyl-3-hydroxyhexyl methacrylate, glycerin monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol Call monomethacrylate, poly (ethylene glycol - propylene glycol) monomethacrylate, and the like. The methacrylate monomer having a hydroxyl group may be used alone or in combination of two or more.

From the viewpoint of obtaining appropriate adhesion to the adherend and good peelability, the methacrylate monomer having a hydroxyl group is preferably an alkyl methacrylate having a hydroxyl group, such as 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 6- More preferably, it comprises at least one selected from the group consisting of hydroxyhexyl methacrylate, 10-hydroxydecyl methacrylate and 12-hydroxylauryl methacrylate, from 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate and 6-hydroxyhexyl methacrylate. More preferably, at least one selected from the group consisting of:

The acrylic copolymer B contains a structural unit Bx derived from a (meth) acrylic acid alkyl ester having no hydroxyl group, preferably as a main component.

The ratio of the structural unit Bx to the total structural unit of the acrylic copolymer B is preferably 50% by mass or more, more preferably 75% by mass or more, and further preferably 80% by mass or more.

Specific examples and preferred examples of the (meth) acrylic acid alkyl ester having no hydroxyl group include the specific examples and preferred examples described in the section of the acrylic copolymer A described above.

The acrylic copolymer B is a structural unit z derived from a monomer having a hydroxyl group other than the structural unit b in addition to the structural unit b derived from a methacrylate monomer having a hydroxyl group, for example, a structural unit derived from an acrylate monomer having a hydroxyl group. May be included. Specific examples of the acrylate monomer having a hydroxyl group described in the section of the acrylic copolymer A described above can be given.

When the acrylic copolymer B contains the structural unit z, it is preferable that the content rate of the structural unit z with respect to all the structural units of the acrylic copolymer B is 7 mass% or less. By making the content rate of the structural unit z with respect to all the structural units of the acryl-type copolymer B 7 mass% or less, the excessive progress of a crosslinking reaction can be suppressed and zipping can be suppressed. The content of the structural unit z relative to all the structural units of the acrylic copolymer B is more preferably 5% by mass or less, and further preferably 3% by mass or less.

In addition to the structural unit Bx derived from a (meth) acrylic acid alkyl ester having no hydroxyl group, the structural unit b derived from a methacrylate monomer having a hydroxyl group, and an optional structural unit z, the acrylic copolymer B includes: The structural unit d derived from other monomers other than these may be included as needed. When the acrylic copolymer B includes the structural unit d, the monomer used for forming the structural unit d may be one type or two or more types. Specific examples and preferred examples of the monomer used for forming the structural unit d when the acrylic copolymer B includes the structural unit d include the components described in the section of the acrylic copolymer A described above. Specific examples and preferred examples of the monomer used for forming the unit c can be given.

When the acrylic copolymer B includes the structural unit d, the content of the structural unit d is preferably 10% by mass or less with respect to the total mass of the structural units in the acrylic copolymer B. % Or less is more preferable.

The weight average molecular weight (Mw) of the acrylic copolymer B is smaller than the weight average molecular weight of the acrylic copolymer A. When the weight average molecular weight (Mw) of the acrylic copolymer B is smaller than the weight average molecular weight of the acrylic copolymer A, it is easy to ensure the wettability of the pressure-sensitive adhesive composition.

The weight average molecular weight (Mw) of the acrylic copolymer B is preferably in the range of 100,000 to 500,000, more preferably in the range of 150,000 to 450,000, and in the range of 200,000 to 400,000. Is more preferable.
When the Mw of the acrylic copolymer B is 100,000 or more, contamination of the adherend due to the generation of the low molecular acrylic copolymer B can be further suppressed. Moreover, when the Mw of the acrylic copolymer B is 500,000 or less, the adhesive force at the time of re-peeling does not become too large, and the adhesive film can be more easily peeled off.

The dispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic copolymer B is not particularly limited, but it is adhesive and suppresses contamination of the adherend. In view of the above, the range of 1 to 30 is preferable.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer B can be measured by the method described in the section of the acrylic copolymer A described above.

The glass transition temperature (Tg) of the acrylic copolymer B is preferably −40 ° C. or lower. When the Tg of the acrylic copolymer B is −40 ° C. or lower, the flowability of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition is excellent, and the familiarity to the adherend is good. The Tg of the acrylic copolymer B is more preferably −45 ° C. or less, and further preferably −50 ° C. or less. The Tg of the acrylic copolymer B can be determined by the calculation formula described in the section of the acrylic copolymer A described above.

The content of the acrylic copolymer B in the pressure-sensitive adhesive composition is in the range of 10% by mass to 60% by mass with respect to the total mass of the pressure-sensitive adhesive composition, from the viewpoint of adhesion and suppression of contamination to the adherend. Preferably, it is in the range of 15 mass% to 55 mass%, more preferably in the range of 20 mass% to 55 mass%.

In the pressure-sensitive adhesive composition of the present invention, the content ratio (A / B) of (meth) acrylic copolymer A to acrylic copolymer B is in the range of 90/10 to 40/60 on a mass basis. Is preferred. If the content ratio of the acrylic copolymer A exceeds 90% by mass, the easy peelability after the heat treatment may be deteriorated. Moreover, when the content rate of the acrylic copolymer B exceeds 60 mass%, the easy peelability after heat processing may deteriorate.
In the pressure-sensitive adhesive composition of the present invention, the content ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B is preferably in the range of 85/15 to 45/55 on a mass basis, The range of ~ 55/45 is more preferred.

In the pressure-sensitive adhesive composition of the present invention, the ratio of the weight average molecular weight of the acrylic copolymer B to the weight average molecular weight of the mixture of the acrylic copolymer A and the acrylic copolymer B is 0.1 to 0.00. A range of 5 is preferable. If the ratio is less than 0.1, the contamination may be deteriorated. Moreover, when the said ratio exceeds 0.5, adhesive force will raise after heat processing, and peelability may deteriorate.
The weight average molecular weight of the mixture of the acrylic copolymer A and the acrylic copolymer B means a weighted mean square value calculated by the following formula 2.
[AMw × AMw × A + BMw × BMw × B] / [AMw × A + BMw × B]
... (Formula 2)
In the above formula 2,
AMw represents the weight average molecular weight of the acrylic copolymer A,
BMw represents the weight average molecular weight of the acrylic copolymer B,
A and B represent the mass A of the acrylic copolymer A and the mass of the acrylic copolymer B contained in the pressure-sensitive adhesive composition, respectively.

In the pressure-sensitive adhesive composition of the present invention, the content of the structural unit a in the total mass of the acrylic copolymer A and the acrylic copolymer B is in the range of 4% by mass to 12%, and the content of the structural unit b The rate is preferably in the range of 4% by mass to 12% by mass. Thereby, an adhesive film can be easily peeled even after heat processing, and the contamination with respect to a to-be-adhered body can also be suppressed effectively.

In the pressure-sensitive adhesive composition of the present invention, the content of the structural unit a in the total mass of the acrylic copolymer A and the acrylic copolymer B is in the range of 5% by mass to 10% by mass, and the above structural unit The content of b is more preferably in the range of 6% by mass to 11% by mass, and in particular, the content of the structural unit a is in the range of 6% by mass to 8%, and the content of the structural unit b is Is more preferably in the range of 8% by mass to 10% by mass.

(Acrylic copolymer polymerization method)
The method for polymerizing acrylic copolymer A and acrylic copolymer B (hereinafter collectively referred to as acrylic copolymer) used in the pressure-sensitive adhesive composition of the present invention is not particularly limited. As the polymerization method, known methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like can be applied. Among these, a solution polymerization method is preferable in that a pressure-sensitive adhesive composition is produced by mixing a copolymer obtained by polymerization, 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 a chain transfer agent used as necessary are generally charged in a polymerization tank, and stirred in a nitrogen stream or at the reflux temperature of the organic solvent. The reaction is carried out by heating for several hours. 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 aromatic substances such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha. Aliphatic hydrocarbons, n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil, and other aliphatic or alicyclic hydrocarbons, ethyl acetate , Esters such as n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone , Ketones such as methylcyclohexanone, ethylene glycol Glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other glycol ethers, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, Examples thereof include alcohols such as n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

Among the organic solvents, it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction of esters, ketones, and the like when the acrylic copolymer is polymerized. In particular, ethyl acetate, methyl ethyl ketone, acetone, and the like are preferable from the viewpoints of the solubility of the acrylic copolymer and the ease of the polymerization reaction.

As the polymerization initiator, it is possible to use organic peroxides, azo compounds, and the like used in ordinary solution polymerization.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonato, di-2-ethylhexylperoxydi. 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, 2,2-bi (4,4-di -t- octyl peroxy cyclohexyl) butane and the like.
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.

Among the polymerization initiators, when the acrylic copolymer is polymerized, 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. In this case, the amount of the polymerization initiator used is preferably in the range of 0.01 to 2 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the acrylic copolymer. A range of 1 part by mass to 1 part by mass is more preferable.

In the production of the acrylic copolymer, 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; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; α-methylstyrene, anthracene, phenanthrene, fluorene Aromatic compounds such as 9-phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol and p-nitrotoluene; benzoquinone, 2,3, Benzoquinone derivatives such as 5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, Bromotrichloromethane, tribromomethane, 3-chloro -Halogenated hydrocarbons such as 1-propene; Aldehydes such as chloral and furaldehyde: Alkyl mercaptans having 1 to 18 carbon atoms; Aromatic mercaptans such as thiophenol and toluene mercaptan; Carbon number of mercaptoacetic acid and mercaptoacetic acid Examples thereof include alkyl esters having 1 to 10; hydroxyalkyl mercaptans having 1 to 12 carbon atoms; and terpenes such as binene and terpinolene.

The amount of the chain transfer agent used can be, for example, in the range of 0.005 parts by mass to 10.0 parts by mass with respect to 100 parts by mass of the total amount of monomers constituting the acrylic copolymer.

The polymerization temperature during the polymerization reaction is preferably in the range of about 30 ° C. to 180 ° C., more preferably in the range of 50 ° C. to 150 ° C. In particular, the polymerization temperature for producing an acrylic copolymer is more preferably in the range of 50 ° C. to 90 ° C., and further preferably in the range of 50 ° C. to 80 ° C.

(Isocyanate compound)
The pressure-sensitive adhesive composition of the present invention contains an isocyanate compound. The content of the isocyanate compound is, for example, 0.4 equivalent to 2.2 equivalents based on the total amount of hydroxyl groups contained in the acrylic copolymer A and the hydroxyl groups contained in the acrylic copolymer B. It can be a range. That is, the isocyanate group contained in the isocyanate compound is 0.4 equivalent to 2.2 equivalents relative to 1 equivalent of the hydroxyl group obtained by totaling the hydroxyl group contained in the acrylic copolymer A and the hydroxyl group contained in the acrylic copolymer B. An amount of an isocyanate compound in an equivalent range can be contained. By containing the isocyanate compound in an amount within the above range, an increase in the adhesive strength after the heat treatment can be further suppressed, and contamination on the adherend can be further suppressed.

Examples of the isocyanate compound include aromatic polyisocyanate compounds such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate; hexamethylene diisocyanate (HMDI), isophorone diisocyanate, and hydrogen of the above-described aromatic polyisocyanate compound. Chain or cyclic aliphatic polyisocyanate compounds such as additives; 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 can be used individually by 1 type or in mixture of 2 or more types.

As the isocyanate compound, in particular, when used in applications where the transparency of the pressure-sensitive adhesive composition is important, a biuret of a chain or cyclic aliphatic polyisocyanate compound and a chain or cyclic aliphatic polyisocyanate compound. At least one selected from the group consisting of a dimer, a trimer, and an adduct is preferable. An isocyanate compound having an isocyanurate structure, which is a trimer of hexamethylene diisocyanate, an adduct of hexamethylene diisocyanate, and hexa More preferred is at least one selected from the group consisting of a biuret of methylene diisocyanate. 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.

A commercially available product can be used as the isocyanate compound. Examples of commercially available products include “Coronate HX”, “Coronate HL-S”, “Coronate L”, “Coronate 2031”, “Coronate 2030”, “Coronate 2234”, “Coronate 2785”, “Aquanate 200”, “Aquanate 210” (manufactured by Nippon Polyurethane Co., Ltd.), “Sumijour N3300”, “Desmodule N3400”, “Sumijoule N-75” (manufactured by Sumitomo Bayer Urethane Co., Ltd.), “Duranate E-405” -80T "," Duranate 24A-100 "," Duranate TSE-100 "(manufactured by Asahi Kasei Corporation)," Takenate D-110N "," Takenate D-120N "," Takenate M-631N "" MT- " "Orestar NP1200" [Mitsui Takeda Chemical Co., Ltd. ] It can be preferably used those which are commercially available by the trade names such as.

The content of the isocyanate compound in the pressure-sensitive adhesive composition of the present invention is 0.6 equivalents to 1.% with respect to the total amount of hydroxyl groups contained in the acrylic copolymer A and hydroxyl groups contained in the acrylic copolymer B. It is more preferably 8 equivalents, and even more preferably 0.7 equivalents to 1.3 equivalents. That is, the isocyanate group contained in the isocyanate compound is 0.6 equivalent to 1.about.1 equivalent to the total hydroxyl group equivalent of the hydroxyl group contained in the acrylic copolymer A and the hydroxyl group contained in the acrylic copolymer B. The amount is preferably in the range of 8 equivalents, more preferably in the range of 0.7 equivalents to 1.3 equivalents.

(Other ingredients)
In addition to the acrylic copolymer A, the acrylic copolymer B, and the isocyanate compound, the pressure-sensitive adhesive composition of the present invention includes various additives in amounts that do not impair the effect exhibited by the pressure-sensitive adhesive composition. It may contain a solvent, a weather resistance stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, a polymer other than the acrylic copolymer A and the acrylic copolymer B, and the like. . Content in case an adhesive composition contains these components can be set suitably.

<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. The pressure-sensitive adhesive film of the present invention is excellent in low contamination with respect to an adherend in addition to pressure-sensitive adhesive properties, because the pressure-sensitive adhesive layer is constituted as a layer derived from the pressure-sensitive adhesive composition of the present invention. Thereby, the productivity of the optical member is improved and the yield is improved.

If the base material which comprises the adhesive film of this invention can form an adhesive layer on it, it can be selected from arbitrary materials.
From the viewpoint of inspection and management of optical members by fluoroscopy, the base material is, for example, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, etc. The sheet | seat or film which consists of a system resin etc. can be mentioned. Among them, a polyester resin base material is preferable from the viewpoint of surface protection performance, and a polyethylene terephthalate resin base material is particularly preferable from the viewpoint of practicality.

The thickness of the substrate can be selected according to the use and is not particularly limited, but is generally 500 μm or less. Among these, a preferable thickness is in the range of 5 μm to 300 μm, and a more preferable range is about 10 μm to 200 μm.

The formation method in particular of the adhesive layer provided on a base material is not restrict | limited, It can carry out by the method used normally. For example, by a method including a step of directly applying the pressure-sensitive adhesive composition of the present invention to a base material which is a base film in a state as it is or diluted with a solvent as necessary, and drying to remove the solvent. It can be carried out.
As another method, first, the pressure-sensitive adhesive composition of the present invention is applied onto a release sheet such as paper or polyester film that has been subjected to a release treatment with a silicone resin, and then dried by heating to form a pressure-sensitive adhesive layer. Then, a method may be used in which the surface of the release sheet on which the pressure-sensitive adhesive layer is formed is brought into contact with the substrate and pressed to transfer the pressure-sensitive adhesive layer to the substrate.
If necessary, a release film may be laminated on the surface of the pressure-sensitive adhesive layer on the substrate thus prepared.

The pressure-sensitive adhesive layer is preferably in a state where the acrylic copolymer A and the acrylic copolymer B are crosslinked by an isocyanate compound contained in the pressure-sensitive adhesive composition. Thereby, coexistence with the adhesiveness of an adhesive layer and the low pollution property with respect to an adherend is attained. The conditions for cross-linking acrylic copolymer A and acrylic copolymer B with an isocyanate compound are not particularly limited. For example, the adhesive film can be crosslinked by heating.

The pressure-sensitive adhesive layer has sufficient adhesive strength to adherends such as optical members (adhesive strength when peeling at low speed is sufficiently large), and can be easily peeled off when peeling at medium speed (medium speed) It is preferable that the adhesive strength at the time of peeling is not increased.
Furthermore, the pressure-sensitive adhesive layer is not only applied to an adherend having a sufficient fluidity and a smooth surface, but also when used for an adherend having minute irregularities on the surface. It is preferable that the surface of the dressed body can be sufficiently wetted and has good conformability (the cut end does not turn up when cut).

That is, the adhesive force of 180 ° peel at 23 ° C. to the adherend of the adhesive layer is such that the adhesive force (peeling force) at a peeling speed of 10 m / min (medium speed peeling) is 0.6 N / 25 mm or less. preferable. More preferably, it is 0.3 N / 25 mm or less.
It can peel easily because the adhesive force at the time of medium speed peeling is 0.6 N / 25 mm or less. In particular, the peelability at a wide width is improved.

The thickness of the pressure-sensitive adhesive layer formed on the substrate can be appropriately set according to the adhesive force required for the protective film, the surface roughness of the adherend, and the like. Generally, it 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.

Applications of the pressure-sensitive adhesive film of the present invention include surface protective films for optical members subjected to heat treatment such as hard coat PET, surface protective films used in the production process of electronic members such as flexible printed boards, and reinforcing films. It is done. 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 in the heat treatment step and can be easily peeled off without contamination after the heat treatment step.
Among them, since the pressure-sensitive adhesive composition of the present invention has high transparency, the pressure-sensitive adhesive film provided with the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention is inspected for appearance inspection and the like in a state of being bonded to an adherend. A process can be performed. For this reason, it is suitable for the surface protection film use of optical members, such as hard coat PET.
The surface protective film of the optical member is laminated on the surface of the optical member to protect the surface of the optical member from being contaminated or damaged. The optical member is subjected to heat treatment such as a high-temperature dry printing step and an etching step while the surface protective film is laminated on the optical member. Thereafter, when the surface protection becomes unnecessary, the optical member is peeled off.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Unless otherwise specified, “part” and “%” are based on mass.

-Production of acrylic copolymer A and acrylic copolymer B-
(Production Example A1)
In a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a sequential dropping device, 100 parts of ethyl acetate, 66.3 parts of 2-ethylhexyl acrylate (2EHA) as an acrylic acid alkyl ester having no hydroxyl group, and a hydroxyl group 5.7 parts of 4-hydroxybutyl acrylate (4HBA) was added as an acrylate monomer, and the temperature in the reaction vessel was raised until reflux occurred while stirring. Ten minutes after the start of reflux, a solution of asobisisobutyronitrile (AIBN) dissolved in ethyl acetate as a polymerization initiator was added dropwise, and after completion of the addition, the reaction was completed over an additional 120 minutes. After completion of the reaction, the reaction mixture was diluted with ethyl acetate so that the solid content was 35% by mass to obtain a solution of acrylic copolymer A1.
Table 2 shows the content (mass%), weight average molecular weight (Mw), and Tg value of 2EHA and 4HBA of the obtained acrylic copolymer A1. The weight average molecular weight (Mw, unit: 10,000) and the Tg value are measured by the method described above.
The “solid content” is the amount of residue obtained by removing volatile components such as a solvent from the solution of the acrylic copolymer A1.

(Production Examples A2 to A26)
In Production Example A1, the composition of the acrylate monomer having 2EHA and the hydroxyl group as an alkyl acrylate ester having no hydroxyl group is changed as shown in Table 1, and as shown in Table 1 below by adjusting the amount of solvent and initiator. A solution of acrylic copolymers A2 to A26 was obtained in the same manner as in Production Example A1, except that the molecular weight was adjusted to. In the acrylic copolymer A17, 2-hydroxyethyl acrylate (2HEA) was used as an acrylate monomer having a hydroxyl group. Table 1 shows the composition (mass%), weight average molecular weight (Mw, unit: 10,000), and Tg value of the obtained acrylic copolymers A2 to A26.

(Production Examples B1 to B26)
In Production Example A1, 2-hydroxyethyl methacrylate (2HEMA) or 4-hydroxybutyl methacrylate (4HBMA) was used as a methacrylate monomer having a hydroxyl group instead of an acrylate monomer having a hydroxyl group, and the composition was changed as shown in Table 1. In addition, the acrylic copolymers B1 to B26 were obtained in the same manner as in Production Example A1, except that the molecular weight was adjusted as shown in Table 1 below by adjusting the amount of the solvent and the amount of the initiator. Table 1 shows the composition (mass%), weight average molecular weight (Mw, unit: 10,000), and Tg value of the obtained acrylic copolymers B1 to B26.

(Example 1)
-Preparation of adhesive composition-
As acrylic copolymer A, the acrylic copolymer A1 obtained in Production Example A1 (solid content: 35 parts by mass) 60 parts by mass, and acrylic copolymer B as the acrylic copolymer B obtained in Production Example B1 40 parts by mass of a solution (solid content: 35 parts by mass) of the copolymer B1 and 5.5 parts by mass of an isocyanate compound (Sumidule N3300 manufactured by Sumika Bayer Urethane Co., Ltd.) (hydroxyl group contained in the acrylic copolymer A1) And the isocyanate group contained in the isocyanate compound is 1.00 equivalent with respect to 1 equivalent of the total hydroxyl group contained in the acrylic copolymer B1, and a crosslinking catalyst (ADK STAB OT-1, manufactured by ADEKA Corporation, active ingredient) : 100 parts by mass) diluted 300-fold with acetylacetone was mixed with 2.1 parts by mass and stirred sufficiently to obtain an adhesive composition. Using the obtained pressure-sensitive adhesive composition, a test pressure-sensitive adhesive film was prepared according to the following method for preparing a test pressure-sensitive adhesive film, and various tests were performed.

-Preparation of adhesive film for testing-
Using the pressure-sensitive adhesive composition obtained above, a test pressure-sensitive adhesive film was produced as follows.
An adhesive composition was applied on a polyethylene terephthalate (PET) film (Tetron film HPE 50 μm, manufactured by Teijin DuPont Films Ltd.) so that the coating amount after drying was 20 g / m 2, and a hot-air circulating dryer And dried at 100 ° C. for 60 seconds to form an adhesive layer. Thereafter, a PET film was placed on the release film whose surface was protected with a silicone release agent so that the pressure-sensitive adhesive layer was in contact with the pressure-sensitive adhesive nip roll. Thereafter, curing was performed for 2 days in an environment of 23 ° C. and 50% RH to obtain a test adhesive film.

-Measurement and evaluation-
[1. Initial adhesive strength]
The test adhesive film produced above is cut into a size of 25 mm × 150 mm, and the release film is peeled off from the obtained adhesive film piece.
As the adherend, a double-sided tape (NITTO No. 5000N, manufactured by Nitto Denko Co., Ltd.) was used to prepare a SUS plate with a polyimide film (Kapton Film 100H, manufactured by Toray DuPont Co., Ltd.) in advance. Then, an adhesive film was pasted on the polyimide film, and a 2 kg rubber roll was reciprocated once to press-bond, thereby preparing a test sample. This test sample was left for 1 hour in an environment of 23 ° C. and 50% RH. Then, the adhesive force in 180 degree peeling at the time of peeling an adhesive film to a long side (150 mm) direction was measured on the conditions of peeling speed 10m / min (medium speed peeling). Table 3 shows the measurement results.

[2. Adhesive strength after heat treatment]
The test adhesive film prepared above was cut to a size of 25 mm × 150 mm, the release film was peeled off from the obtained adhesive film piece, and attached to a polyimide film (Kapton Film 100H, manufactured by Toray DuPont Co., Ltd.). A 2 kg rubber roll was reciprocated once for pressure bonding.
This test sample was allowed to stand in an environment of 23 ° C. and 50% RH for 1 hour, 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. Then, the adhesive force in 180 degree peeling at the time of peeling an adhesive film to a long side (150 mm) direction was measured on the conditions of peeling speed 10m / min (medium speed peeling). Table 3 shows the measurement results.
In addition, the "Evaluation" column of "Adhesive strength" in Table 3 is described according to the following criteria.
A: When the adhesive strength after heat treatment is more than 0.05 N / 25 mm and 0.3 N / 25 mm or less (workability is very good).
B: The adhesive strength after heat treatment is more than 0.01 N / 25 mm and not more than 0.05 N / 25 mm, or more than 0.3 N / 25 mm and not more than 0.45 N / 25 mm (good workability).
C: Adhesive strength after heat treatment exceeds 0.45 N / 25 mm and is 0.6 N / 25 mm or less (inferior workability but within an allowable range).
D: Adhesive strength after heat treatment exceeds 0.6 N / 25 mm or 0.01 N / 25 mm or less (defect).

[3. Contamination (water contact angle after peeling)]
2 μL of pure water was dropped on the surface of the polyimide film after peeling off the test protective film, which was used for the measurement of the adhesive strength after the heat treatment in 2 above, and a contact angle measuring device (Contact angle device) 30 seconds after the dropping. The contact angle (θ1) of water was measured using a meter CA-D (manufactured by Kyowa Interface Science Co., Ltd.). The absolute value (Δθ = | θ1-θ0 |) of the difference between the obtained value and the water contact angle (θ0 = 64 °) of the polyimide film that had been measured in advance and was not attached with the test protective film It was used as an index of pollution. The results are shown in Table 3.
In addition, the “evaluation” column of “contamination” in Table 3 is described according to the following criteria.
A: When Δθ is 2.0 or less (low contamination and very good).
B: When Δθ exceeds 2.0 and is 4.5 or less (contamination is low and good).
C: When Δθ is more than 4.5 and 7.0 or less (contamination is low but within an allowable range).
D: C when Δθ exceeds 7.0 (high contamination and poor).

[4. Zipping]
When the difference in strength of the adhesive film is large, zipping (crimping sound) occurs when peeling from the adherend. The occurrence of zipping causes the occurrence of contamination and wrinkles in places with high adhesive strength. The evaluation of zipping is described in Table 3 by calculating the ratio (maximum adhesive force / minimum adhesive force) to the minimum value of the maximum value of the adhesive force of the pressure-sensitive adhesive film in the measurement of the adhesive force after the heat treatment of 2 above. did.
The “evaluation” column of “zipping” in Table 3 is described according to the following criteria.
A: When the ratio of the maximum value of the adhesive force to the minimum value is 1.0 or less (the occurrence of zipping is sufficiently suppressed and very good).
B: When the value of the ratio of the maximum value of the adhesive force to the minimum value is more than 1.0 and not more than 2.0 (the occurrence of zipping is suppressed and good).
C: When the value of the ratio of the maximum value of the adhesive force to the minimum value is more than 2.0 and 5.0 or less (zipping occurs but within an allowable range).
D: The value of the ratio of the maximum value of the adhesive force to the minimum value exceeds 5.0 (zipping is noticeably generated).

(Examples 2 to 22, Comparative Examples 1 to 4)
The types and ratios of the acrylic copolymer A and the acrylic copolymer B are changed as shown in Table 2, and the amount of the isocyanate compound is a hydroxyl group and an acrylic copolymer contained in the acrylic copolymer A. A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the amount of isocyanate group contained in the isocyanate compound was adjusted to 1.00 equivalent with respect to 1 equivalent of the total hydroxyl group contained in B. A test adhesive film was prepared in the same manner as in Example 1 using the prepared adhesive composition. The obtained test adhesive film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

As shown in Table 3, the total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is in the range of 40 mgKOH / g to 90 mgKOH / g, and the hydroxyl value of the hydroxyl value a A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive compositions of Examples 1 to 22 having a ratio to the value b (hydroxyl value a / hydroxyl value b) in the range of 0.5 to 7.0, It was good or within an acceptable range in all of the evaluation of adhesive strength and contamination.
The pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of Comparative Example 1 in which the total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is less than 40 mg KOH / g is a pressure-sensitive adhesive layer. The strength was too high and the adhesive strength was poor.
The pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of Comparative Example 2 in which the total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B exceeds 90 mgKOH / g, The adhesive strength of the adhesive layer was lost.
The pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of Comparative Example 3 in which the ratio of the hydroxyl value a to the hydroxyl value b (hydroxyl value a / hydroxyl value b) was less than 0.5 was highly contaminated.
The pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of Comparative Example 4 in which the ratio of the hydroxyl value a to the hydroxyl value b (hydroxyl value a / hydroxyl value b) exceeds 7.0 has an adhesive strength by heat treatment. The increase in the temperature was large, and zipping occurred remarkably, which was outside the allowable range.

The disclosures of Japanese Patent Application No. 2013-112947 filed on May 29, 2013 and Japanese Patent Application No. 2014-058818 filed on March 20, 2014 are hereby incorporated by reference in their entirety. Captured in the book.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

An acrylic copolymer A containing a structural unit Ax derived from a (meth) acrylic acid alkyl ester having no hydroxyl group and a structural unit a derived from an acrylate monomer having a hydroxyl group;
The structural unit Bx derived from a (meth) acrylic acid alkyl ester having no hydroxyl group and the structural unit b derived from a methacrylate monomer having a hydroxyl group, the weight average molecular weight being smaller than the weight average molecular weight of the acrylic copolymer A An acrylic copolymer B having
An isocyanate compound,
The total of the hydroxyl value a of the acrylic copolymer A and the hydroxyl value b of the acrylic copolymer B is in the range of 40 mgKOH / g to 90 mgKOH / g,
The ratio of the hydroxyl value a to the hydroxyl value b is in the range of 0.5 to 7.0.
Adhesive composition.
The ratio of the weight average molecular weight of the acrylic copolymer B to the weight average molecular weight of the mixture of the acrylic copolymer A and the acrylic copolymer B is in the range of 0.1 to 0.5. The pressure-sensitive adhesive composition according to claim 1.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the ratio of the hydroxyl value a to the hydroxyl value b is in the range of 0.5 to 2.0.
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein a content of the structural unit a in the acrylic copolymer A with respect to all structural units is 30% by mass or less.
The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the content of the structural unit b in the acrylic copolymer B with respect to all structural units is 10% by mass or more.
The content of the isocyanate compound is 0.4 equivalent to 2.2 equivalent based on the amount of hydroxyl group contained in the acrylic copolymer A and the acrylic copolymer B. 6. The pressure-sensitive adhesive composition according to any one of 5 above.
The pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein each of the acrylic copolymer A and the acrylic copolymer B has a glass transition temperature (Tg) of -40 ° C or lower. object.
The weight average molecular weight of the acrylic copolymer A is in the range of 400,000 to 1,500,000, and the weight average molecular weight of the acrylic copolymer B is in the range of 100,000 to 500,000. 8. The pressure-sensitive adhesive composition according to any one of 7 above.
A substrate;
A pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition according to any one of claims 1 to 8, provided on the base material,
An adhesive film having
An adhesive film attaching step for attaching the adhesive film according to claim 9 to the surface of the article so that the adhesive layer and the surface are in contact with each other;
A heat treatment step of heating the article to which the adhesive film has been attached in the attaching step;
A peeling step of peeling the adhesive film from the surface of the article heated in the heat treatment step,
A method for processing an article comprising: