KR20140018112A - Protective film - Google Patents

Abstract

The present invention relates to a protective film having an adhesion layer, is formed by an adhesive composition including (matte) acrylic ester copolymers (A), which are obtained by the living radical polymerization of the adhesion layer and have weight-average molecular weight (Mw) of 400000-2000000 and molecular weight distribution (Mw/Mn) value of less than 2.5, and isocyanate group crosslinking agents (B) and organic tin compounds (C). The (matte) acrylic ester copolymers (A) includes tellurium metal. The weight ratio of the organic tin compound (C) and the tellurium metal is 2:1-20:1. The present invention is able to provide the protective film which is attached to a substrate with sufficient adhesion and minimizes the attachment of residues on the substrate in exfoliation.

Description

Protective film {PROTECTIVE FILM}

The present invention relates to a protective film having an adhesive layer. More specifically, the present invention relates to a protective film having very few residual monomers and low molecular weight components in the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and having very little adhesion of residues to the adherend.

The protective film is conventionally used for optical purposes such as various image display devices such as LCD (liquid crystal display device), touch panel, CRT (brown tube), PDP (plasma display panel), EL (electroluminescence) display, optical recording. In the medium and the like, it has been used for the purpose of surface protection, anti-glare (anti-glare, anti-glare), anti-reflection, and the like. It is also used in LCDs to protect polarizers. This protective film generally has an adhesive layer on one side of the base film, and on the other side, a functional coating layer such as antistatic performance or antifouling performance, or a hard coating layer is formed as necessary.

Therefore, since an excellent optical characteristic and formation of an adhesive are comparatively easy, the acrylic adhesive which uses a (meth) acrylic acid ester type copolymer as a main component is used for the said adhesive layer. It is known that when a protective film having such an adhesive layer is attached to an adherend with an adhesive layer interposed therebetween, a residue hardly noticeable is attached. It is considered that this residue originates from the residual monomer and low molecular weight component which exist in the (meth) acrylic acid ester type copolymer which is a main component, when an acrylic adhesive is used.

Patent Document 1 discloses an acrylic pressure-sensitive adhesive having a low molecular weight component, but it cannot be said to be sufficient as an effect of reducing the adhesion amount of the residue.

By the way, living polymerization is known as a superposition | polymerization in which a growth reaction advances but a stop reaction and a chain transfer reaction do not occur in a polymer polymerization reaction. That is, the growth ends of living polymers, i.e. polymers polymerized by living polymerization, remain active even after the monomers are consumed, and polymerization is resumed when the monomers are added. Therefore, it is known that the molecular weight of the polymer increases in proportion to the consumption of the monomer, and that a polymer having an even molecular weight, that is, a narrow molecular weight distribution is obtained.

On the other hand, in radical polymerization, the life of a growth radical is very short and it has a polymerization stop mechanism called a two-molecule stop reaction. For this reason, in the past, it was thought that living polymerization of radicals was impossible, but since stable radicals have recently been found even in the presence of air, studies on living radical polymerization have been actively conducted, and various methods have been developed.

For example, Patent Literatures 2 and 3 disclose techniques for producing living radical polymers having a uniform molecular weight by polymerizing vinyl monomers using organic tellurium compounds as living radical polymerization initiators.

Patent Document 4 discloses that by applying the living radical polymerization, the low molecular weight component having a molecular weight of 50,000 or less can be 5 mass% or less. However, the organic tellurium compound used in the polymerization initiator is a catalyst poison to the crosslinking agent. By acting as a delay, crosslinking delay of the pressure-sensitive adhesive composition occurs, and there has been a problem that heavy peeling occurs over time in the protective film containing the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2001-214142 [Patent Document 2] Japanese Unexamined Patent Publication No. 2006-299278 [Patent Document 3] International Publication No. 2004/014962 Pamphlet [Patent Document 4] Japanese Unexamined Patent Publication No. 2011-74380

The present invention has been made under such a situation, and even when a (meth) acrylic acid ester copolymer is selected as the main component in the pressure-sensitive adhesive composition, it is sufficient for protection when the protective film having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is attached to various adherends. An object of the present invention is to provide a protective film that exhibits adhesive strength and has very little adhesion to an adherend of a residue caused by the pressure-sensitive adhesive composition during peeling.

MEANS TO SOLVE THE PROBLEM The present inventors earned the following insights as a result of careful research in order to achieve the said objective.

As the main component of the pressure-sensitive adhesive composition, a (meth) acrylic acid ester copolymer having a specific property obtained by living radical polymerization is selected, and the copolymer, a isocyanate-based crosslinking agent, and a predetermined ratio with respect to the tellurium metal contained in the copolymer. It turned out that the protective film which has an adhesive layer formed by the adhesive composition containing an organotin compound may be suitable for the objective. The present invention has been completed based on these facts.

That is, the present invention provides a (meth) acrylic acid ester copolymer (A), an isocyanate-based crosslinking agent (B) having a weight average molecular weight of 400,000 to 2 million and a molecular weight distribution of less than 2.5 obtained by [1] living radical polymerization, and organic A protective film having a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing a tin compound (C), wherein the organic tin compound (C) is contained 2 to 20 times by mass with respect to the tellurium metal contained in the component (A). A protective film characterized by the above-mentioned [1], wherein the proportion of the low molecular weight component having a weight average molecular weight of 100,000 or less in the protective film, [2] (meth) acrylic acid ester copolymer (A) is less than 5% by mass, and [3] ] Providing the protective film as described in said [1] or [2] which has an adhesive layer in one side of a plastic film, and the release sheet was laminated | stacked on the exposed surface side of the said adhesive layer.

In addition, the present invention has the following aspects.

A protective film having a <1> adhesive layer, wherein the pressure sensitive adhesive layer has a weight average molecular weight (Mw) of 400,000 to 2 million and a molecular weight distribution (Mw / Mn) value of less than 2.5 (meth) acrylic acid ester system It is formed by the adhesive composition containing a copolymer (A), an isocyanate type crosslinking agent (B), and an organic tin compound (C),

The (meth) acrylic acid ester copolymer (A) further contains a tellurium metal,

The ratio of the said organic tin compound (C) and the said tellurium metal in the said adhesive composition is 2: 1-20: 1 by mass ratio, The protective film,

<2> The proportion of the low molecular weight component having a weight average molecular weight of 100,000 or less in the (meth) acrylic acid ester copolymer (A) is less than 5% by mass relative to the total mass of the (meth) acrylic acid ester copolymer (A). The protective film as described in said <1>,

<3> The protective film according to <1> or <2>, further comprising a release sheet, wherein the pressure-sensitive adhesive layer is laminated on at least one side of the plastic film, and the release sheet is a protective layer laminated on the pressure-sensitive adhesive layer. film.

According to the present invention, a protective film having a pressure-sensitive adhesive layer that can adhere to the adherend with sufficient adhesive force for protection when attached to the adherend, and has very little adhesion of the residue to the adherend during peeling. can do. Since the protective film of this invention can suppress the fall of the function by adhesion of a residue, it can apply to the functional optical member which requires the cleanliness of the surface at a high level. In addition, by containing the organic tin compound in a predetermined ratio in the pressure-sensitive adhesive composition, it is possible to improve the crosslinking delay of the pressure-sensitive adhesive composition and the heavy peeling of the protective film, which have been a problem in conventional formulations.

Here, 'sufficient adhesive force' means that the adhesive force of the protective film is 50 mN / 25 mm or more. In addition, "heavy peeling" means that the peeling force of a release sheet increases without stabilization with time.

The protective film of the present invention is a protective film having an adhesive layer, wherein the adhesive layer has a weight average molecular weight (Mw) of 400,000 to 2 million and a molecular weight distribution (Mw / Mn) value of less than 2.5 (meth) obtained by living radical polymerization. It is formed by an adhesive composition comprising an acrylic ester copolymer (A), an isocyanate crosslinker (B), and an organic tin compound (C), wherein the (meth) acrylic acid ester copolymer (A) forms a tellurium metal. Furthermore, the ratio of the said organic tin compound (C) and said tellurium metal in the said adhesive composition is 2: 1-20: 1 by mass ratio, It is characterized by the above-mentioned.

&Lt; Pressure sensitive adhesive composition &

The protective film of the present invention is a (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 400,000 to 2 million and a molecular weight distribution (Mw / Mn) value of less than 2.5 obtained by living radical polymerization, and an isocyanate crosslinking agent (B ) And a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing an organic tin compound (C). In one embodiment of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a solvent in addition to the above components. Hereinafter, each component in an adhesive composition is demonstrated.

[(Meth) acrylic acid ester copolymer (A)]

The (meth) acrylic acid ester system copolymer (A) is a component contained as a main component in the adhesive composition which forms the adhesive layer in the protective film which concerns on this invention, and has a characteristic shown below. Here, "main component" means the component contained 50 mass% or more, Preferably it is 80 mass% or more, Especially preferably, 90 mass% or more with respect to the gross mass (solid content conversion value) of an adhesive composition. In addition, an upper limit is not specifically limited, but the ratio of remaining components except the essential component of this invention, such as a crosslinking agent (B), an organic tin compound (C), etc. becomes an upper limit. In addition, "(meth) acrylic acid ester" refers to both an acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

(Characteristic of Component (A))

The (meth) acrylic acid ester copolymer (A) has a weight average molecular weight (Mw) in the range of 400,000 to 2 million, and a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn) ratio) value is less than 2.5. When the weight average molecular weight of the said component (A) is less than 400,000, the component amount which a weight average molecular weight is 100,000 or less inevitably increases and it cannot prevent adhesion of the residue to an adherend. On the other hand, when Mw of component (A) exceeds 2 million, smoothness of a coating surface will worsen by the viscosity raise of component (A). In addition, a large amount of solvent is required to suppress such an increase in viscosity, which is not preferable from the viewpoint of manufacturing cost or on environmental measures. Moreover, when the weight average molecular weight of component (A) is larger than 2 million, control of a growth reaction will become inadequate at the time of superposition | polymerization, and molecular weight distribution may expand.

That is, if the Mw of component (A) is in the range of 400,000 to 2 million, it prevents adhesion of the residue to the adherend, further suppresses the smoothness of the coated surface due to the viscosity increase, and the cost increase, and controls the molecular weight distribution. It is easy to do it, and it is preferable.

In addition, in view of a small amount of residue, adhesive durability, coating suitability, and the like, the weight average molecular weight of the component (A) is preferably 500,000 to 1.5 million, more preferably 850,000 to 1.2 million. Here, the "adhesion durability" refers to a performance in which the adhesive layer is not lifted or peeled even when stored in a state where it is attached to an adherend such as glass under a high temperature condition or a moist heat condition for a predetermined period of time. In addition, the "applicability of the coating" means that the solubility in the solvent is excellent, it is possible to form a smooth coating surface without using a large amount of solvent.

In addition, it is preferable that the value of the molecular weight distribution (Mw / Mn ratio) of component (A) is less than 2.5. When the molecular weight distribution value of component (A) is 2.5 or more, it becomes difficult to achieve the reduction of the low molecular weight component in the said (meth) acrylic acid ester-type copolymer (A) mentioned later, and when the objective of this invention cannot be achieved There is. Therefore, the preferable molecular weight distribution (Mw / Mn ratio) value is less than 2.5. Especially preferably, it is 1.0-2.2.

Moreover, in the said (meth) acrylic acid ester type copolymer (A), it is preferable that the ratio of the low molecular weight component whose weight average molecular weight (Mw) is 100,000 or less is less than 5 mass% with respect to the total mass of component (A). That is, in the present invention, 'low molecular weight component' means a polymer component having a Mw of 100,000 or less. If the ratio of this low molecular weight component is 5 mass% or more with respect to the gross mass of a component (A), the protective film which has an adhesive layer formed using the adhesive composition containing a component (A) to a to-be-adhered body through the said adhesive layer. In the case of adhesion, the adhesion of the residue to the adherend may not be suppressed to a sufficiently low level. That is, when the ratio of the low molecular weight component contained in component (A) is less than 5 mass% with respect to the total mass of component (A), when the protective film of this invention is peeled from an adherend, the residue of a to-be-adhered body will be It is preferable because adhesion becomes less.

Therefore, it is more preferable that the ratio of the low molecular weight component whose weight average molecular weight is 100,000 or less is 3 mass% or less with respect to the gross mass of component (A), It is more preferable that it is 2 mass% or less, It is especially preferable that it is 1 mass% or less. . The lower limit of the low molecular weight component in the component (A) is not particularly limited, but considering the manufacturing cost and the like, the lower limit value of the lower molecular weight component is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, based on the total mass of the component (A). Do.

In addition, the ratio of the said low molecular weight component, a weight average molecular weight (Mw), and a number average molecular weight (Mn) are the standard polystyrene conversion values measured by the gel permeation chromatography (GPC) method.

In addition, the adhesion amount of the residue to a to-be-adhered body can be calculated | required by the residual particle number test which measures the number of residual foreign substances on the surface of a to-be-adhered body by a laser surface inspection apparatus.

(Composition of Component (A))

The (meth) acrylic acid ester copolymer (A) is a (meth) acrylic acid ester monomer unit (a) (hereinafter referred to as a nonfunctional monomer unit (a)) having an ester moiety which is an alkyl group having 1 to 20 carbon atoms. , (Meth) acrylic acid ester monomer unit (b) (hereinafter also referred to as functional monomer unit (b)) having a reactive functional group in a mass ratio (non-functional monomer unit (a): functional monomer unit (b)) It is preferable to include in the ratio of 80: 20-99.9: 0.1. The reactive functional group in the said functional monomer unit (b) is a functional group used as the crosslinking point bridge | crosslinked by the crosslinking agent mentioned later. Therefore, the non-functional monomer unit (a) and the functional monomer unit (b), in which the content of the functional monomer unit (b) is contained in the total amount of the non-functional monomer unit (a), that is, in the structure of the component (A) When the total amount of is set to 100 mass%, the crosslinking point of the (meth) acrylic acid ester copolymer (A) is less than 0.1 mass%, and there is a fear that the crosslinking agent will not be sufficiently crosslinked by the crosslinking agent described later. Therefore, the adhesive composition containing such a component (A) may fall in adhesive force or adhesive durability. From this point of view, the content of the functional monomer unit (b) is more preferably 0.5 mass% or more, more preferably 1 mass% based on the total amount (100 mass%) of the non-functional monomer unit (a) and the functional monomer unit (b). It is especially preferable that it is above.

On the other hand, when content of the said functional monomer unit (b) exceeds 20 mass%, it will become easy to gelatinize at the time of manufacture of the adhesive composition containing a component (A). In addition, the pot life after adding the crosslinking agent to component (A) becomes too short, which may cause workability problems. Moreover, the cohesion force of the adhesive obtained may become high too much, and adhesive force may fall, and adhesiveness with respect to a to-be-adhered body may worsen. From this point of view, the content of the functional monomer unit (b) is more preferably 10% by mass or less.

In addition, the functional group of the functional monomer unit (b) may be coordinated with a radical initiator (organic tellurium compound), and the content of the functional monomer unit (b) is 8 mass% from the viewpoint of eliminating the risk of insufficient polymerization control. It is especially preferable that it is the following.

The (meth) acrylic acid ester copolymer (A) comprises a (meth) acrylic acid ester having the ester moiety which is an alkyl group having 1 to 20 carbon atoms to form the nonfunctional monomer unit (a), and the functional monomer unit (b). It can manufacture by copolymerizing the (meth) acrylic acid ester which has the reactive functional group to form, and the other monomer used as needed.

Examples of (meth) acrylic acid esters having an ester moiety having 1 to 20 carbon atoms of an alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl ( Meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) Acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used independently or may be used in combination of 2 or more type.

On the other hand, examples of the (meth) acrylic acid ester having a reactive functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy. Hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monomethyl aminoethyl (meth) acrylate, And monoalkyl aminoalkyl (meth) acrylates such as monoethyl aminoethyl (meth) acrylate, monomethyl aminopropyl (meth) acrylate, and monoethyl aminopropyl (meth) acrylate. These may be used alone or in combination of two or more thereof. In the present invention, hydroxyalkyl (meth) acrylate is preferably used from the viewpoint of crosslinkability and the like.

In addition, examples of other monomers to be used as desired include vinyl esters such as vinyl acetate and vinyl propionate; Olefins such as ethylene, propylene and isobutylene; Halogenated olefins such as vinyl chloride and vinylidene chloride; Styrene-based monomers such as styrene and? -Methylstyrene; Diene monomers such as butadiene, isoprene and chloroprene; Nitrile monomers such as acrylonitrile and methacrylonitrile; Acrylamide, such as acrylamide, N-methyl acrylamide, and N, N- dimethyl acrylamide, etc. are mentioned. These may be used independently or may be used in combination of 2 or more type.

As said (meth) acrylic-ester type copolymer (A), the copolymer of butyl acrylate and 4-hydroxybutyl acrylate is excellent in the adhesive performance of the adhesive layer formed of the adhesive composition containing the said component (A). , Copolymers of butyl acrylate, 2-ethylhexyl acrylate and 4-hydroxybutyl acrylate, copolymers of butyl acrylate and 2-hydroxyethyl acrylate, butyl acrylate, cyclohexyl acrylate and 4-hydroxy Preferred are copolymers of hydroxybutyl acrylate or copolymers of butyl acrylate, methyl acrylate and 4-hydroxybutyl acrylate.

The content of the 4-hydroxybutyl acrylate unit or 2-hydroxyethyl acrylate unit, that is, the functional monomer unit (b), which is a crosslinking point in the copolymer obtained by the above preferred combination is determined by the above-mentioned non-functional monomer unit ( About 0.5-10 mass% is preferable with respect to the total amount (100 mass%) of a) and a functional monomer unit (b), and 1-8 mass% is especially preferable.

(Manufacturing method of component (A))

The (meth) acrylic acid ester copolymer (A) is a copolymer polymerized by living radical polymerization. Living radical polymerization is characterized by a very gentle reaction at the active point compared to free radical polymerization. That is, in free radical polymerization, since the reaction at an active site is very fast, it is thought that the monomer with low reactivity will superpose | polymerize after polymerizing from a monomer with high reactivity. On the other hand, in living radical polymerization, since the reaction at the active point is gentle, it is considered that the polymerization proceeds evenly without being affected by monomer reactivity, and any copolymer obtained is more uniform in composition. Therefore, (meth) acrylic acid ester type copolymer (A) obtained by living radical polymerization produces | generates the (meth) acrylic acid ester type homopolymer comprised only with the nonfunctional monomeric unit (a) compared with the polymer obtained by free radical polymerization. I think the ratio is overwhelmingly small. For this reason, the (meth) acrylic acid ester type copolymer (A) obtained by living radical polymerization has a low weight average molecular weight, for example, even if Mw is about 400,000, it is a crosslinking agent (B) mentioned later. Is very likely to crosslink. As a result, the protective film of the present invention having the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition composed mainly of the (meth) acrylic acid ester copolymer (A) obtained by living radical polymerization has a very high adhesion of the residue to the adherend. It is considered that it can suppress to a low level.

As a manufacturing method of component (A), a conventionally well-known living radical polymerization method, for example, the atom transfer radical polymerization method (ATRP polymerization method) which uses an atom transfer radical polymerization agent as a polymerization control agent, a reversible addition-breaking chain The polymerization method by reversible addition-breaking chain transfer using a transfer agent (RAFT polymerization method), the polymerization method using an organic tellurium compound as a polymerization initiator, etc. can be employ | adopted. Among these living radical polymerization methods, the method of using an organic tellurium compound as a polymerization initiator is preferable at the point which can superpose | polymerize also in the controllability of molecular weight and a water system. Hereinafter, the method of using an organic tellurium compound as a polymerization initiator is demonstrated.

<Living radical polymerization of component (A) using an organic tellurium compound>

The (meth) acrylic acid ester copolymer (A) may be formed of a monomer using, for example, a living radical polymerization initiator (hereinafter referred to as an organic tellurium compound (I)) represented by the following general formula (1). It can manufacture by the method including the process of polymerizing a mixture (polymerization process).

Wherein R ¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group or an aromatic heterocyclic group, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁴ is an aryl group , Substituted aryl group, aromatic heterocyclic group, acyl group, oxycarbonyl group or cyano group.

The group represented by R ¹ is specifically as follows.

Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, secondary-butyl group, tert-butyl group, cyclobutyl group, n-pentyl group and C1-C8 linear, branched or cyclic alkyl groups, such as n-hexyl group, n-heptyl group, n-octyl group, etc. are mentioned. As a preferable alkyl group, it is a C1-C4 linear or branched alkyl group, More preferably, it is a methyl group or an ethyl group.

Examples of the aryl group include a phenyl group, a naphthyl group, and the like, and examples of the substituted aryl group include a phenyl group having a substituent and a naphthyl group having a substituent. Can be mentioned. As a substituent of the aryl group which has the said substituent, the carbonyl containing group represented by a halogen atom, a hydroxyl group, an alkoxy group, an amino group, a nitro group, a cyano group, -COR ⁵ (R <^5> is C1-C8) Alkyl groups, aryl groups, alkoxy groups having 1 to 8 carbon atoms, aryloxy groups), sulfonyl groups, trifluoromethyl groups and the like. Preferred aryl groups include phenyl groups substituted with phenyl groups and trifluoromethyl groups. In addition, these substituents are preferably substituted one or two, preferably para position or ortho position.

The groups represented by R ² and R ³ are specifically as follows.

The alkyl group having 1 to 8 carbon atoms is as defined for R ¹ above.

The group represented by R ⁴ is specifically as follows.

The aryl group, substituted aryl group, aromatic heterocyclic group is as defined for R ¹ above.

Examples of the acyl group include formyl group, acetyl group and benzoyl group.

As the oxycarbonyl group, a group represented by -COOR ⁶ (R ⁶ = H, an alkyl group having 1 to 8 carbon atoms, an aryl group) is preferable. For example, a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, propoxycarbon And a silyl group, n-butoxycarbonyl group, secondary-butoxycarbonyl group, tert-butoxycarbonyl group, n-pentoxycarbonyl group, and phenoxycarbonyl group. Preferred oxycarbonyl groups include methoxycarbonyl group and ethoxycarbonyl group.

Examples of the group represented by R ⁴ include an aryl group, a substituted aryl group, and an oxycarbonyl group. Preferred aryl groups include phenyl groups. Preferred substituted aryl groups include phenyl groups substituted with halogen atoms and phenyl groups substituted with trifluoromethyl. In addition, in the case of a halogen atom, these substituents are what is substituted by 1-5 pieces. In the case of an alkoxy group or a trifluoromethyl group, one or two substituents are mentioned. In the case of one substitution, a para position or an ortho position is preferable, and in the case of two substitutions, a meta position is preferable. Preferred oxycarbonyl groups include methoxycarbonyl group and ethoxycarbonyl group.

As preferable organic tellurium compound (I) of General formula (1), R <^1> represents a C1-C4 alkyl group, R <^2> and R <^3> represent a hydrogen atom or a C1-C4 alkyl group, R <^4> is an aryl group, The compound which shows the substituted aryl group or oxycarbonyl group is mentioned. Especially preferably, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁴ represents a phenyl group, a substituted phenyl group, a methoxycarbonyl group, or The compound which shows an ethoxy carbonyl group is mentioned.

The organic tellurium compound of General formula (1) is as follows specifically ,.

The organic tellurium compound is (methylteranyl-methyl) benzene, (1-methylteranyl-ethyl) benzene, (2-methylteranyl-propyl) benzene, 1-chloro-4- (methylteranyl-methyl) benzene , 1-hydroxy-4- (methylteranyl-methyl) benzene, 1-methoxy-4- (methylteranyl-methyl) benzene, 1-amino-4- (methylteranyl-methyl) benzene, 1- Nitro-4- (methylteranyl-methyl) benzene, 1-cyano-4- (methylteranyl-methyl) benzene, 1-methylcarbonyl-4- (methylteranyl-methyl) benzene, 1-phenylcarbon Neyl-4- (methylteranyl-methyl) benzene, 1-methoxycarbonyl-4- (methylteranyl-methyl) benzene, 1-phenoxycarbonyl-4- (methylteranyl-methyl) benzene, 1 Sulfonyl-4- (methylteranyl-methyl) benzene, 1-trifluoromethyl-4- (methylteranyl-methyl) benzene, 1-chloro-4- (1-methylteranyl-ethyl) benzene, 1-hydroxy-4- (1-methylteranyl-ethyl) benzene, 1-methoxy-4- (1-methylteranyl-ethyl) benzene, 1-amino-4- (1-methylteranyl-ethyl ) Benzene, 1-nitro-4- (1-methylteranyl-ethyl) benzene, 1-cyano-4- ( 1-methylteranyl-ethyl) benzene, 1-methylcarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-phenylcarbonyl-4- (1-methylteranyl-ethyl) benzene, 1- Methoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-phenoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-sulfonyl-4- (1-methylterra Neyl-ethyl) benzene, 1-trifluoromethyl-4- (1-methylteranyl-ethyl) benzene [or 1- (1-methylteranyl-ethyl) -4-trifluoromethyl benzene], 1- (1-methylteranyl-ethyl) -3,5-bis-trifluoromethyl benzene, 1,2,3,4,5-pentafluoro-6- (1-methylteranyl-ethyl) benzene, 1 -Chloro-4- (2-methylteranyl-propyl) benzene, 1-hydroxy-4- (2-methylteranyl-propyl) benzene, 1-methoxy-4- (2-methylteranyl-propyl) Benzene, 1-amino-4- (2-methylteranyl-propyl) benzene, 1-nitro-4- (2-methylteranyl-propyl) benzene, 1-cyano-4- (2-methylteranyl- Propyl) benzene, 1-methylcarbonyl-4- (2-methylteranyl-propyl) benzene, 1-phenylcarbonyl-4- (2-methylteranyl-propyl) benzene, 1-methoxycarbonyl-4- (2-methylteranyl-propyl) benzene, 1-phenoxycarbonyl-4- (2-methylteranyl-propyl) benzene, 1-sulfonyl-4- (2- Methylteranyl-propyl) benzene, 1-trifluoromethyl-4- (2-methylteranyl-propyl) benzene, 2- (methylteranyl-methyl) pyridine, 2- (1-methylteranyl-ethyl) Pyridine, 2- (2-methylteranyl-propyl) pyridine, 2-methyl-2-methylteranyl-propanal, 3-methyl-3-methylteranyl-2-butanone, 2-methylteranyl-ethane Methyl acid, 2-methylteranyl-methyl propionate, 2-methylteranyl-2-methylpropionate, 2-methylteranyl-ethyl ethane, 2-methylteranyl-ethyl propionate, 2-methylteranyl-2 Ethyl methyl propionate [or ethyl-2-methyl-2-methylteranyl-propionate], 2- (n-butylterranyl) -2-methyl ethyl propionate [or ethyl-2-methyl-2-n- Butylteranyl-propionate], 2-methylteranyl acetonitrile, 2-methylteranyl propionitrile, 2-methyl-2-methylteranyl propioni Reel, and the like are exemplified - (2-phenyl-propyl TB carbonyl) benzene (phenyl TB carbonyl-methyl) benzene, (1-phenyl TB carbonyl) benzene.

In addition, the methyl teranyl, 1-methyl teranyl, 2-methyl teranyl moiety is ethyl teranyl, 1-ethyl teranyl, 2-ethyl teranyl, butyl teranyl, 1-butyl teranyl, 2- All compounds modified with butylterranyl are also included. Preferably, (methylteranyl-methyl) benzene, (1-methylteranyl-ethyl) benzene, (2-methylteranyl-propyl) benzene, 1-chloro-4- (1-methylteranyl-ethyl) Benzene, 1-trifluoromethyl-4- (1-methylteranyl-ethyl) benzene [1- (1-methylteranyl-ethyl) -4-trifluoromethyl benzene], 2-methylteranyl-2 -Methyl methyl propionate, 2-methylteranyl-2-methyl ethyl propionate [ethyl-2-methyl-2-methylteranyl-propionate], 2- (n-butylteranyl) -2-methyl ethyl propionate [ Ethyl-2-methyl-2-n-butylteranyl-propionate], 1- (1-methylteranyl-ethyl) -3,5-bis-trifluoromethyl benzene, 1,2,3,4 , 5-pentafluoro-6- (1-methylteranyl-ethyl) benzene, 2-methylteranyl propionitrile, 2-methyl-2-methylteranyl propionitrile, (ethylteranyl-methyl) benzene , (1-ethylteranyl-ethyl) benzene, (2-ethylteranyl-propyl) benzene, 2-ethylteranyl-2-methylpropionate, 2-ethylteranyl-2-methyl propionic acid , 2-ethylteranyl propionitrile, 2-methyl-2-ethylteranyl propionitrile, (n-butylteranyl-methyl) benzene, (1-n-butylteranyl-ethyl) benzene, (2- n-butylterranyl-propyl) benzene, 2-n-butylteranyl-2-methyl propionate, 2-n-butylterranyl-2-methyl ethyl propionate, 2-n-butylteranyl propionitrile, 2 -Methyl-2-n-butylterranyl propionitrile is mentioned.

The organic tellurium compound of General formula (1) may be used individually by 1 type, or may be used in combination of 2 or more type. Among them, ethyl-2-methyl-2-n-butylteranyl-propionate, 2-n-butylteranyl-2-methyl methyl propionate, or (n- Preference is given to using butylterranyl-methyl) benzene.

In one embodiment of the present invention, the polymerization step in the method for producing component (A) may be carried out by adding to the organic tellurium compound and optionally adding an azo polymerization initiator as a polymerization promoter. The azo polymerization initiator is not particularly limited as long as it has an effect of the present invention as long as it is an initiator used for ordinary radical polymerization. Specifically, 2,2'-azobis (isobutyronitrile) (AIBN), 2,2'-azobis (2-methyl butyronitrile) (AMBN), 2,2'-azobis (2, 4-dimethyl valeronitrile) (ADVN), 1,1'-azobis (1-cyclohexane carbonitrile) (ACHN), dimethyl-2,2'-azobis isobutyrate (MAIB), 4,4'- Azobis (4-cyano valeric acid) (ACVA), 1,1'-azobis (1-acetoxy-1-phenylethane), 2,2'-azobis (2-methylbutyl amide), 2, 2'-azobis (4-methoxy-2,4-dimethyl valeronitrile), 2,2'-azobis (2-methylaminopropane) dihydrochloride, 2,2'-azobis [2- (2 -Imidazolin-2-yl) propane], 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propion amide], 2,2'-azobis (2,4,4 -Trimethylpentane), 2-cyano-2-propyl azo formamide, 2,2'-azobis (N-butyl-2-methyl propionamide), 2,2'-azobis (N-cyclohexyl-2 -Methyl propion amide), and the like.

When the azo-based polymerization initiator is used in combination with the organic tellurium compound, it is preferably 0.01 to 100 mol, more preferably 0.1 to 100 mol, and more preferably 1 mol of the organic tellurium compound of the general formula (1) used as the polymerization initiator. Preferably it is used in the ratio of 0.1-5 mol.

The method for producing the (meth) acrylic acid ester copolymer (A) by living radical polymerization is specifically as follows.

In the container substituted with an inert gas, the above-mentioned monomer mixture, the living radical polymerization initiator (organic tellurium compound) of General formula (1), and an azo polymerization initiator are mixed as needed. At this time, examples of the inert gas include nitrogen, argon, helium, and the like. Preferably, argon and nitrogen are mentioned. Especially preferably, nitrogen is mentioned.

The usage-amount of the living radical polymerization initiator (organic tellurium compound) of General formula (1) with respect to a monomer can be suitably adjusted according to the weight average molecular weight or molecular weight distribution value made into the objective of a (meth) acrylic-ester type copolymer (A). The preferred amount of use is divided by the weight average molecular weight (Mw) of the copolymer (A) for the sum of the values obtained by multiplying the molecular weight of each monomer by the input ratio (wherein the amount of the organic tellurium compound is expressed as 'mol'). ), More preferably about 0.3 to 3 times the above value, depending on the weight average molecular weight.

In the method for preparing component (A), the polymerization process is usually carried out without solvent, but may also be carried out in an organic solvent generally used in radical polymerization. Solvents that can be used are, for example, benzene, toluene, N, N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), acetone, chloroform, carbon tetrachloride, tetrahydrofuran (THF), ethyl acetate, tri Fluoromethyl benzene and the like. Moreover, an aqueous solvent can also be used, For example, water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, etc. are mentioned. Although the usage-amount of a solvent can also be adjusted suitably, 0.01-100 ml is preferable with respect to 1 g of monomers, for example, 0.05-10 ml is more preferable, 0.05-0.5 ml is especially preferable.

Next, while stirring the said mixture, component (A) is superposed | polymerized. Although superposition | polymerization temperature and reaction time can be suitably adjusted according to the weight average molecular weight or molecular weight distribution of the target component (A), Usually, it is preferable to stir at 60-150 degreeC for 5 to 100 hours. Moreover, Preferably, it can stir at 80-120 degreeC for 10 to 30 hours. At this time, the pressure is usually performed at normal pressure, but may be performed under pressure or reduced pressure in the range of 0.01 to 10 MPa.

After the completion of the reaction, it is preferable to perform a purification step of purifying the target component (A) by removing the solvent or residual monomer under reduced pressure, precipitating filtration, reprecipitation, column separation, or the like by a conventional method, if necessary. Do. Reaction treatment can be carried out by any treatment method as long as the target product is not impaired.

For example, in (meth) acrylic acid ester type copolymer (A), in order to make the ratio of the low molecular weight component whose weight average molecular weight (Mw) contained in it be 100,000 or less into less than 5 mass%, the component (A) is mentioned below. It is preferable to include the purification process which refine | purifies by a method.

(Refining step of component (A))

Specific methods for the purification method of component (A) are firstly a lower alcohol such as methanol, ethanol, n-propanol, isopropanol, or an aliphatic hydrocarbon having 5 to 10 carbon atoms such as pentane, hexane, heptane, preferably methanol or hexane 100 In a mass part, component (A) is added at a ratio of about 1-30 mass parts as solid content, it stirred under room temperature, and precipitates. Subsequently, the precipitate is subjected to solid-liquid separation by a method such as decantation, followed by washing with the lower alcohol or aliphatic hydrocarbon having 5 to 10 carbon atoms. By including such a purification process, the ratio of the low molecular weight component whose weight average molecular weight (Mw) in a component (A) is 100,000 or less can be made into less than 5 mass%. Therefore, the component (A) after purification is contained in the adhesive composition as a main component.

In the adhesive composition of this invention, in order to manufacture a (meth) acrylic-ester type copolymer (A) by polymerizing the mixture of each monomer mentioned above by living radical polymerization, the said component (A) can be made into a random copolymer. Regardless of the kind of monomer used for polymerization, the random copolymer can obtain a copolymer in the proportion (molar ratio) of the monomer to be reacted. That is, by superposing | polymerizing the mixture of each monomer mentioned above by living radical polymerization, the component (A) which randomized each monomer superposed | polymerized irrespective of the kind of monomer, ie, the reactivity of a monomer, can be obtained.

The living radical polymerization initiator of the general formula (1) used in the present invention can perform excellent molecular weight control and molecular weight distribution control under very mild conditions.

In this invention, the weight average molecular weight of the (meth) acrylic acid ester type copolymer (A) which is a living radical copolymer is controlled by reaction time (polymerization time) and the addition amount of the living radical polymerization initiator (organic tellurium compound) of General formula (1). It is possible to do Specifically, in order to increase the weight average molecular weight, the blending ratio of the organic tellurium compound to the monomer can be reduced, and the polymerization time can be lengthened. However, this method requires a long time to obtain the component (A) having a large weight average molecular weight. Therefore, in order to reduce the polymerization time, a method of increasing the polymerization temperature or adding the azo polymerization initiator as a polymerization accelerator may be mentioned. However, if the polymerization temperature is too high or the amount of the azo polymerization initiator added is too large, the molecular weight distribution value of the component (A) is increased, so that the molecular weight distribution of the component (A) is also added, and the reaction conditions need to be adjusted.

Thus, the (meth) acrylic acid ester system whose weight average molecular weight is 400,000-2 million, molecular weight distribution (Mw / Mn ratio) is less than 2.5, and the ratio of the low molecular weight component whose weight average molecular weight is 100,000 or less is less than 5 mass%. Copolymer (A) can be obtained easily.

[Isocyanate Crosslinking Agent (B)]

In the said adhesive composition, an isocyanate type crosslinking agent (B) (henceforth a "crosslinking agent (B)") is contained as an essential component.

Here, examples of the isocyanate-based crosslinking agent (B) include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate, Alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate and the like, biuret and isocyanurate thereof, and low molecular weight active hydrogens such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane and castor oil Adducts, for example trimethylol propane-modified tolylene diisocyanate, which are reactants of the compound, and the like.

In this invention, these crosslinking agents may be used individually by 1 type as a crosslinking agent (B), or may be used in combination of 2 or more type. Among them, from the viewpoint of adhesion durability, it is preferably at least one selected from isocyanurates of aliphatic polyisocyanates such as aromatic polyisocyanates and HDI. Moreover, although the usage-amount changes with kinds of crosslinking agent, it is 0.01-20 mass parts normally with respect to 100 mass parts of said (meth) acrylic-ester type copolymers (A), Preferably it is 0.1-10 mass parts, Especially preferably, Is selected in the range of 0.5 to 5 parts by mass.

[Organic Tin Compound (C)]

In the said adhesive composition, an organic tin compound (C) is contained as an essential component.

In the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition, when the tellurium compound derived from a polymerization initiator is included in the pressure-sensitive adhesive composition, the delayed crosslinking of the pressure-sensitive adhesive composition and the heavy peeling of the protective film including the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition are problematic. It became. However, the said problem can be solved by containing an organic tin compound in the said adhesive composition.

As this organotin compound (C), dibutyltin dilaurate (DBTDL), dibutyltin dioctylate (DBTDO), etc. which were used conventionally as a crosslinking promoter are preferable from a viewpoint of the said effect. The content of the organic tin compound (C) in the pressure-sensitive adhesive composition is in the range of 2 to 20 times by mass based on the tellurium metal derived from the polymerization initiator contained in the (meth) acrylic acid ester copolymer (A). That is, it is preferable that the ratio of the organotin compound (C) and tellurium metal in an adhesive composition is 2: 1-20: 1 by mass ratio. When the ratio of the organic tin compound (C) in the pressure-sensitive adhesive composition is less than 2 in terms of mass relative to the tellurium metal in the pressure-sensitive adhesive composition, the above effects are not sufficiently exhibited, and the object of the present invention is not achieved. On the other hand, when the ratio of the organic tin compound (C) in an adhesive composition exceeds 20 by weight ratio with respect to the tellurium metal in an adhesive composition, the improvement of an effect is not recognized very much compared with the content of the organic compound (C). That is, when the ratio of the organic tin compound (C) and the tellurium metal in the pressure-sensitive adhesive composition is 2: 1 to 20: 1 by mass ratio, the heavy foil of the protective film including the delayed crosslinking of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition. It is preferable because the effect of suppressing liquefaction can be sufficiently obtained. The more preferable ratio of the organotin compound (C) and tellurium metal in an adhesive composition is 2: 1-15: 1 by mass ratio.

[Preparation of pressure-sensitive adhesive composition]

The method for preparing the pressure-sensitive adhesive composition used in the present invention is not particularly limited as long as it has the effect of the present invention. For example, the (meth) acrylic acid ester copolymer (A) and isocyanate-based crosslinking agent (B) described above in a solvent ), Organic tin compound (C), and various additives used as necessary, for example, antioxidants, ultraviolet absorbers, antistatic agents, light diffusing agents, light stabilizers, silane coupling agents, leveling agents, antifoaming agents, etc. By mixing, the pressure-sensitive adhesive composition can be prepared.

Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol and butanol, acetone and methyl ethyl ketone , Ketones such as 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, glycol ether solvents such as propylene glycol monomethyl ether, and the like. Can be. These solvent may be used individually by 1 type, or may mix and use 2 or more types.

The solid content concentration of the pressure-sensitive adhesive composition may be in a range in which the composition is suitable for coating, that is, the viscosity of the pressure-sensitive adhesive composition containing the solvent is in the range of 100 to 9000 mPa · s, and is not otherwise limited.

<Protection film>

Next, the protective film of this invention is demonstrated.

The protective film of this invention has an adhesive layer formed by the above-mentioned adhesive composition. Moreover, the laminated | multilayer film of the structure which the said adhesive layer is laminated | stacked on at least one surface of a plastic film, and a release sheet was laminated | stacked on this adhesive layer is preferable, for example.

[Plastic film]

In one embodiment of the protective film of the present invention, the plastic film is used as the substrate. Such plastic films are not limited otherwise as long as they have the effects of the present invention, for example, polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl Cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, poly Sulfone film, polyether ether ketone film, polyether sulfone film, polyether imide film, polyimide film, fluororesin film, polyamide film, acrylic resin film, norbornene-based resin film, cycloolefin resin film and the like. have. In addition, when a protective film is used for optical use, inspection work may be performed in the state which affixed to the to-be-adhered body, or it may be used so that a protective film may be recognized as it is in the state which attached the protective film according to a consumer's preference. Therefore, it is preferable that it is a transparent plastic film as a plastic film.

The thickness of these plastic films is not limited otherwise as long as it has the effect of the present invention, but is appropriately selected, but is usually in the range of 10 to 250 µm, preferably 30 to 200 µm. Moreover, this plastic film can surface-treat on one side or both sides by an oxidation method, an uneven | corrugated method, etc. as needed for the purpose of improving the adhesiveness with the layer formed in the surface. Examples of the oxidation method include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. A treatment method etc. are mentioned, for example. Although these surface treatment methods are suitably selected according to the kind of plastic film, generally, the corona discharge treatment method is used preferably from a viewpoint of an effect, an operation method, etc. Moreover, the thing which carried out the primer treatment to one side or both sides can also be used.

[Pressure sensitive adhesive layer]

In one Embodiment which concerns on the protective film of this invention, the adhesive layer laminated | stacked on at least one surface of the said plastic film can be obtained by directly apply | coating and drying the adhesive composition of this invention mentioned above to a plastic film. Moreover, a release sheet can also be laminated | stacked further on it, the said adhesive composition is apply | coated and dried on the mold release process surface of a release sheet, an adhesive layer is formed, and the adhesive layer with this release sheet adhered to one side of a plastic film. A protective film can also be formed by sticking.

That is, in one Embodiment which concerns on the protective film of this invention, it is preferable that the said adhesive layer contains the reaction hardened | cured material (D) of the said component (A) and the said isocyanate type crosslinking agent (B), The said reaction hardened | cured material It is preferable that (D) contains the said organic tin compound (C) and tellurium metal. That is, it is preferable that the said adhesive layer contains reaction hardened | cured material (D), an organic tin compound (C), and tellurium metal. The tellurium metal contained in an adhesive layer is a component derived from the said organic tellurium compound added as a polymerization initiator of the above-mentioned component (A).

As a method for applying the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer on a plastic film, a predetermined method is known, for example, by a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, a gravure coating method, or the like. The method of apply | coating and drying so that thickness may be used can be used.

The thickness of an adherend layer is about 2-30 micrometers normally, Preferably it is 5-25 micrometers.

Examples of the release sheet include coating a release agent such as silicone resin on paper such as glassine paper, coated paper, laminated paper, and various plastic films. As the plastic film, those exemplified in the plastic film can be appropriately used. Although it does not restrict | limit otherwise about the thickness of this release sheet, it is about 10-100 micrometers normally.

The protective film of the present invention may be one in which a release sheet is usually laminated on the exposed surface side of the pressure-sensitive adhesive layer, that is, the surface not in contact with the plastic sheet, and without using a separate release sheet, the pressure-sensitive adhesive layer laminated surface of the plastic film. The release layer is formed on the opposite side to the surface, the surface of the release layer may be rolled or rolled in a stacked state so as to contact the exposed surface side of the pressure-sensitive adhesive layer.

[Coating layer]

In the protective film of this invention, the coating layer which has antistatic performance and / or antifouling performance can be formed in the surface of the other side in which the adhesive layer of a plastic film is not laminated | stacked.

The coating layer having an antistatic performance can be formed by, for example, applying and drying a coating liquid in which a conductive material is dispersed in a thermoplastic resin matrix to the other surface on which the pressure-sensitive adhesive layer of the plastic film is not laminated.

On the other hand, the coating layer which has antifouling performance can be formed by apply | coating and drying the coating liquid containing fluorine-type resin to the other surface in which the adhesive layer of a plastic film is not laminated | stacked.

As a coating method of the said various coating liquids, the bar coating method, the knife coating method, the roll coating method, the blade coating method, the die coating method, the gravure coating method, etc. can be used, for example.

The thickness of the coating layer having electrical conductivity thus formed is usually about 0.05 to 1 μm, preferably about 0.3 to 0.7 μm, and the thickness of the coating layer having antifouling performance is usually about 1 to 10 nm, preferably about 3 to 8 nm. .

[ Example ]

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

In addition, about the acrylate copolymer obtained by each case, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the weight average molecular weight of standard polystyrene conversion by gel permeation chromatography (GPC) method are 100,000 or less The content of the molecular weight component was determined by the following method.

<GPC method>

Measuring device: High speed column 'TSK gurd column H _XL -H', 'TSK Gel GMH _XL ', 'TSK Gel G2000 H _XL ' (TOSOH CORPORATION) high speed GPC device 'HLC-8120GPC' And all were manufactured by Tosoh Corp. in this order and measured.

Column temperature: 40 ° C, liquid feed rate: 1.0 mL / min, detector: differential refractive index

Moreover, about the protective film obtained by each case, the adhesive force with respect to polymethyl methacrylate (PMMA), the peeling force of the release sheet SP, and the quantity of residual particles (residual particle number test) were calculated | required according to the following method.

(1) adhesion to PMMA

25 mm width and 100 mm length were cut out from the protective film obtained by the following example, the release sheet was peeled off, and it was set as the test piece, and PMMA board (made by MITSUBISHI RAYON CO., LTD., ACRYLITE L001) '] Was a trial version.

After attaching the test specimen and the test plate, the sample was left for 24 hours in an environment of 23 ° C. and a relative humidity of 50%, and maintained at 50% of relative humidity, and 1) a sample left for one week at 23 ° C., 2) at 1 ° C. Adhesion was measured at 25 mm / N for test specimens and test plates for each of samples left for months or samples left at 40 ° C. for 2 weeks.

Except the above conditions, peeling rate 300mm / min, peeling angle 180 ° using a tensile tester (TENENSILON, manufactured by Orientec Co., Ltd.) in accordance with JIS Z 0237: 2009. Adhesive force was measured on condition.

(2) Peeling force of the release sheet SP

About the protective film of each following example, the sample of width 50mm and length 150mm is cut out, and peeling of SP with respect to each sample after leaving for 1 week at 23 degreeC or leaving it for 2 weeks at 40 degreeC under the environment of 50% of relative humidity. The force was measured on the conditions of the peeling speed of 300 mm / min, and the peeling angle of 180 degree using the tensile tester (the "Tensilon" by Orientek Co., Ltd.).

(3) residual particle number test

The protective film obtained by the Example or the comparative example was adhere | attached by reciprocating a 5 kg (49N) rubber roller once to the mirror surface of a 4-inch silicon wafer at room temperature in a clean room, and left for 60 minutes, and peeled. At this time, the number of residual foreign substances of 0.27 micrometer or more in particle size was measured by the laser surface inspection apparatus (made by Hitachi Denshi Engineering Co., Ltd.).

Synthesis Example 1 Synthesis of Organic Tellurium Compound (Ethyl-2-methyl-2-n-butylterranyl-propionate)

6.38 g (50 mmol) of metal tellurium (manufactured by Aldrich, product name 'Tellurium (-40 mesh)') was suspended in 50 ml of tetrahydrofuran (THF), and n-butyl lithium (1.6 mol / L hexane solution manufactured by Aldrich) was added thereto. ] 34.4 ml (55 mmol) was slowly added dropwise at room temperature. The reaction solution was stirred until the metal tellurium disappeared completely. 10.7 g (55 mmol) of ethyl-2-bromo-isobutytylate was added to this reaction solution, and it stirred for 2 hours. After the completion of the reaction, the solvent was concentrated under reduced pressure, followed by distillation under reduced pressure to obtain 8.98 g (yield 59.5%) of ethyl-2-methyl-2-n-butylteranyl propionate as a yellow oily substance.

(1) Preparation of acrylic ester copolymer (A) consisting of random copolymer by living radical polymerization

As the monomer, butyl acrylate [BA, manufactured by Tokyo Chemical Industry Co., Ltd.] and 4-hydroxybutyl acrylate [4HBA, manufactured by Tokyo Kasei Kogyo Co., Ltd.] are used in a mass ratio of 97: 3. An acrylic ester copolymer (A) made of a random copolymer of BA / 4HBA was produced by using a living radical polymerization shown in the following ratio. The properties of this copolymer are shown in Table 1.

<Living Radical Polymerization>

68.5 μl of ethyl-2-methyl-2-n-butylteranyl-propionate prepared in Synthesis Example 1 in a glove box substituted with argon, 107 g of butyl acrylate (as above), 4-hydroxybutyl acrylate 3.3 g (as above) and as a polymerization promoter, 2,2'-azobis (isobutyronitrile) [AIBN; Aldrich Co., Ltd.] was reacted at 60 ° C. for 20 hours.

After completion of the reaction, the reactor was taken out of the glove box, dissolved in 500 ml of ethyl acetate, and the polymer solution was passed through a column made of activated alumina (manufactured by Wako Pure Chemical Industries, Ltd.). . Then, toluene was added so that the viscosity of a polymer solution might be 5000 mPa * s (25 degreeC). Solid content of the obtained polymer was 15 mass%.

In addition, the weight average molecular weight measured by GPC was 100,000 or less, the ratio of the low molecular weight component was 1.95 mass%, the weight average molecular weight of the said component (A) was 1030,000, and molecular weight distribution (Mw / Mn) was 2.06.

The polymer solution was dried and then incinerated, and it was confirmed by ICP / MS (inductively coupled plasma mass spectrometer) that the residual tellurium content with respect to the solid content of the polymer solution was 100 ppm.

(2) Preparation of Adhesive Composition

100 parts by mass (solid content) of the (meth) acrylic acid ester copolymer (A) made of the random copolymer prepared in the above (1) and a crosslinking agent (B), isocyanurate type HDI [Nippon Polyurethane Co., Ltd. NIPPON POLYURETHANE INDUSTRY CO., LTD., Brand name 'CORONATE HX', NCO content: 21.3% by mass, 100% solids] 2.00 parts by mass and 245 ppm of DBTDL are dissolved in methyl ethyl ketone as a solvent. The adhesive composition of 13 mass% of solid content concentration was prepared.

(3) Production of protective film

As a plastic film, the antistatic and antifouling non-treated surface of antistatic and antifouling polyethylene terephthalate film (manufactured by TORAY INDUSTRIES, INC., Trade name 'PET38SLD52') having a thickness of 38 μm is described in the above (2). After apply | coating the adhesive composition obtained by this so that a dry thickness might be set to 5 micrometers with a knife type applicator, it heat-dried at 90 degreeC for 1 minute, and formed the adhesive layer.

Subsequently, the exposed surface side of the adhesive layer obtained above was affixed on the release surface of the release sheet [Lintec Corporation make, brand name 'SP-PET381031'] of thickness 38micrometer, and a plastic film / adhesive layer The protective film which consists of a / release sheet was produced, and various characteristics were calculated | required about this protective film. The results are shown in Table 2.

In the pressure-sensitive adhesive composition of Example 1, the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the amount of DBTDL was changed to 490 ppm, to prepare a protective film. Various characteristics were calculated | required about this protective film. The results are shown in Table 2.

In the pressure-sensitive adhesive composition of Example 1, the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the amount of DBTDL was changed to 979 ppm to prepare a protective film. Various characteristics were calculated | required about this protective film. The results are shown in Table 2.

(Comparative Examples 1 to 4)

In the pressure-sensitive adhesive composition of Example 1, the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the amounts of DBTDL were changed as shown in Table 1, and each protective film was prepared. Various characteristics were calculated | required about each of these protective films. The results are shown in Table 2.

(Comparative Example 5)

(1) Preparation of acrylic ester copolymer by free radical polymerization

As monomer, butyl acrylate (same as above) and 4-hydroxybutyl acrylate (same as above) are used in the ratio of mass ratio 97: 3, and the acrylic acid ester copolymer of BA / 4HBA by the free radical polymerization shown below Prepared. The properties of this copolymer are shown in Table 1.

<Free radical polymerization>

After nitrogen gas was enclosed in a reaction apparatus equipped with a stirrer, a thermometer, a reflux cooler and a nitrogen introduction tube, 90 parts by mass of ethyl acetate, 75 parts by mass of butyl acrylate, 2.3 parts by mass of 4-hydroxybutyl acrylate, and a polymerization initiator 0.2 mass part of 2,2'- azobis (isobutyronitrile) (AIBN) were introduce | transduced, and it stirred for 7 hours at the reflux temperature of ethyl acetate, stirring. 95 mass parts of toluene was added after completion | finish of reaction, and it cooled to room temperature. Then, the acrylic acid ester copolymer which is 13 mass% of solid content was obtained.

Below, it operated like Example 1, the adhesive composition was prepared, and the protective film was further produced. General characteristics of this protective film are shown in Table 2.

Pressure-sensitive adhesive composition Main component, acrylic ester copolymer Coronate
HX DBTDL Furtherance
(Mass ratio) polymerization
Way Weight average
Molecular Weight
(Mw) Molecular Weight
Distribution
(Mw / Mn) Mw 100,000
The following
Component (% by mass)
Te content
(ppm) (phr) (ppm) DBTDL / Te
(Mass ratio) Example 1 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 245 2.5 Example 2 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 490 4.9 Example 3 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 979 9.8 Comparative Example 1 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 0 0.0 Comparative Example 2 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 49 0.5 Comparative Example 3 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 98 1.0 Comparative Example 4 BA / 4HBA
= 97/3 LRP 103 million 2.06 1.95 100 2.00 150 1.5 Comparative Example 5 BA / 4HBA
= 97/3 FRP 950,000 3.75 4.55 0 2.00 - -

[week]

(1) Te content in the acrylic ester copolymer (A) was measured by the following method.

Measuring instrument: ICP / MS

The plymer solution was dried and then incinerated for analysis by ICP / MS. In addition, the abbreviation in Table 1, 2 is as follows.

(2) phr: parts by mass relative to 100 parts by mass of the main component

(3) DBTDL: dibutyl tin dilaurate

(4) BA: Butyl acrylate

(5) 4HBA: 4-hydroxybutyl acrylate

(6) Coronate HX: Nippon Polyurethane Co., Ltd., a brand name, isocyanurate type HDI, NCO content: 23.1 mass%, solid content: 100%

(7) LRP: living radical polymerization

(8) FRP: free radical polymerization

Protective film Adhesion (vs PMMA)
(mN / 25mm) Peeling force (large SP)
(mN / 25mm)
Residual Particle Counting Test (4/4 inch Wafer) 23 ℃
1 W 23 ℃
1M 40 ℃
2 W 23 ℃
1 W 40 ℃
2 W Example 1 415 400 390 15 39 110 Example 2 405 400 400 15 35 100 Example 3 400 395 400 15 33 125 Comparative Example 1 2400 1680 1100 18 63 120 Comparative Example 2 780 570 380 20 47 100 Comparative Example 3 650 500 400 20 44 100 Comparative Example 4 580 460 420 18 42 110 Comparative Example 5 410 420 415 18 18 2300

[Week] 1W: 1 week, 2W: 2 weeks, 1M: 1 month

As can be seen from Table 2, the adhesive force of the protective film of the Example has a small decrease in the adhesive force over time as compared with the adhesive force of the protective film of the comparative example. In addition, about the peeling force with respect to a release sheet, the case of the protective film of a comparative example becomes large as time passes compared with the protective film of an Example, and heavy peeling advances.

In the residual particle number test, when the protective film of Examples 1 to 3 by living radical polymerization was compared with the protective film of Comparative Example 5 by free radical polymerization, the protective film of Comparative Example 5 was found to have a high number by the residual particle number test. There were a lot of 7800. From these results, it turned out that the protective film of this invention has little adhesion of the residue to a to-be-adhered body, and can prevent the heavy peeling with the passage of time of a protective film.

[Industrial applicability]

The protective film of the present invention has a pressure-sensitive adhesive layer, and since the residual monomer and low molecular weight component in the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer are very small, the adhesion of the residue to the adherend is very small, thereby protecting the surface of various image display apparatuses. In addition, it can use suitably anti-glare property, anti-reflection, etc.

Claims (3)

A protective film having a pressure sensitive adhesive layer, wherein the pressure sensitive adhesive layer has a weight average molecular weight (Mw) of 400,000 to 2 million and a molecular weight distribution (Mw / Mn) value of less than 2.5 (meth) acrylic acid ester copolymer ( A), an isocyanate-based crosslinking agent (B) and an organic tin compound (C) formed by the pressure-sensitive adhesive composition,
The (meth) acrylic acid ester copolymer (A) further contains a tellurium metal,
The ratio of the said organic tin compound (C) and said tellurium metal in the said adhesive composition is 2: 1-20: 1 by mass ratio, The protective film characterized by the above-mentioned. The method of claim 1,
The protective film whose ratio of the low molecular weight component whose weight average molecular weight is 100,000 or less in the said (meth) acrylic acid ester-type copolymer (A) is less than 5 mass% with respect to the total mass of the said (meth) acrylic acid ester-type copolymer (A). 3. The method according to claim 1 or 2,
Additionally includes a release sheet,
The pressure-sensitive adhesive layer is laminated on at least one side of the plastic film,
A protective film in which the release sheet is laminated on the pressure-sensitive adhesive layer.