WO2013005830A1

WO2013005830A1 - Adhesive composition and adhesive sheet for surface protection

Info

Publication number: WO2013005830A1
Application number: PCT/JP2012/067327
Authority: WO
Inventors: 豊嶋　克典; 俊之早川; 中村　丈夫; 明彦大久保; 拓哉佐野
Original assignee: 積水化学工業株式会社; Jsr株式会社
Priority date: 2011-07-07
Filing date: 2012-07-06
Publication date: 2013-01-10
Also published as: JP2014169347A; TW201302959A

Abstract

An adhesive composition comprising: a copolymer (i) that is a copolymer (I) having a structure expressed by the general formula [A-B]n (n is an integer of 1-3 inclusive), or a hydrogenation product thereof; and a copolymer (ii) that is a copolymer (II) having a structure expressed by the general formula A-B-A or the general formula (A-B)x-Y (In the formula, x is an integer of one or more, and Y is a coupling agent residue), or a hydrogenation product thereof. The vinyl bond content of the conjugated diene unit of the polymer block (B) is 70-85%, and the content of alkenyl aromatic compound units in all of the polymer blocks (B), on the basis of the total monomer mass of copolymers (i) and (ii), is 15-35 mass% (A: a block comprising primarily alkenyl aromatic compound units in which the alkenyl aromatic compound unit is continuous. B: a block randomly comprising conjugated diene units and alkenyl aromatic compound units.).

Description

Adhesive composition and adhesive sheet for surface protection

The present invention relates to an adhesive composition and an adhesive sheet for surface protection.

Conventionally, when storing or transporting various products (parts) such as optical devices, metal plates, painted metal plates, resin plates, and glass plates, the surface thereof is contaminated or scratched. In order to prevent this, a surface protective film in which an adhesive layer is disposed on one main surface of a polyolefin-based substrate is often used. Such a surface protective film is affixed on the surface of the product for the purpose of surface protection.

The surface protective film is required to prevent unintended peeling (including partial peeling) during storage and transportation of the product. Therefore, the surface protective film needs to have a certain level of adhesive strength. In particular, when a surface protective film is applied to a product (part) having a concavo-convex surface, a large contact area cannot be obtained. Therefore, it is necessary to form a pressure-sensitive adhesive layer having a strong adhesive force. Examples of products (parts) having such a concavo-convex surface include prism sheets and diffusion films that are optical members for liquid crystal displays.

On the other hand, the surface protective film is required to be removed with a small force when the user intends to remove it as in the case of using the product. As a problem related to this, there is an increase in adhesive force due to external factors such as time and temperature (so-called adhesive progress). An example of a situation in which such a problem occurs is that a product with a surface protective film attached thereto is exposed to a high temperature during its transportation and storage. This problem is likely to occur particularly when the surface of the product (adhered body) has an uneven shape.

Furthermore, the surface protective film is required not to contaminate the surface of the product, that is, a part of the adhesive layer does not remain on the surface of the product at the time of peeling. This need is particularly high when the product is an optical film or optical sheet.

By the way, the surface protective film is usually formed in a long shape, wound in a roll shape, and manufactured in the form of a wound body. The surface protection film in the form of a wound body is rewound at the time of use. The surface protective film is also required to have a small force (deployment force) required for unwinding, that is, excellent developability. In addition, when unwinding does not proceed smoothly due to insufficient developability, a so-called stop mark is generated in the adhesive layer, which may damage the appearance of the surface protective film, and is transferred to the product (adhered body). There is a risk of being.

In response to such a demand, Patent Document 1 discloses two types of specific block copolymers having an aromatic alkenyl polymer block and an aromatic alkenyl-conjugated diene copolymer block, or hydrogenated products thereof. By using it in the adhesive layer, it has an appropriate initial adhesive force, has excellent developability, suppresses the adhesion progress, and generates an adhesive layer residue (that is, a part of the adhesive layer is the above adherend). Surface protection films that have been suppressed from remaining on the surface have been proposed.

International Publication No. 2010/029773 Pamphlet

However, there is a need for a surface protective film that further suppresses adhesion and further has excellent developability.

Therefore, an object of the present invention is to provide a pressure-sensitive adhesive composition that makes it possible to produce a surface protective film with suppressed adhesion progress, and a surface protective film with suppressed adhesion progress.

A further object of the present invention is to provide a pressure-sensitive adhesive composition that makes it possible to produce a surface protective film having excellent spreadability, and a surface protective film having excellent spreadability.

By controlling the vinyl bond content of two types of block copolymers containing a conjugated diene compound unit and an aromatic alkenyl compound unit within a specific range, the present inventors have developed a pressure-sensitive adhesive composition containing them. It was found that the progress of the adhesion of the obtained surface protective film can be suppressed.

The present inventors further developed a surface protective film obtained from the pressure-sensitive adhesive composition containing these by controlling the aromatic alkenyl compound content of the above-mentioned two types of block copolymers within a specific range. We found that it can improve the sex.

The present invention provides the aspects of the invention described in the following items.
Item 1.
Copolymer (i): including the following polymer block A and the following polymer block B,
Formula [AB] _n
(In the formula, A represents the polymer block A, B represents the polymer block B, and n represents an integer of 1 to 3.)
A copolymer (I) having a structure represented by the formula:
Copolymer (ii): including the following polymer block A and the following polymer block B,
General formula ABA (the symbols in the formula are as defined above) or general formula (AB) _x -Y (wherein x represents an integer of 1 or more and Y is a coupling agent) Residues and other symbols are as defined above.)
A copolymer (II) having a structure represented by the formula (II) or a hydrogenated product thereof:
The vinyl bond content of the conjugated diene unit in the polymer block B is in the range of 70 to 85%, and
Adhesive having an aromatic alkenyl compound unit content (St (B)) in the range of 15 to 35% by mass in the total polymer block B based on the total monomer mass of the copolymers (i) and (ii) Composition.

Polymer block A:
Polymer block in which aromatic alkenyl compound units are continuous and mainly composed of aromatic alkenyl compound units Polymer block B:
Item 1. An aromatic alkenyl-conjugated diene copolymer block randomly containing conjugated diene units and aromatic alkenyl compound units.
The aromatic alkenyl compound unit content (St (b)) of the entire polymer block B is in the range of 10 to 40% by mass,
The total aromatic alkenyl compound unit content (St (A + B)) of the copolymers (i) and (ii) is in the range of 35 to 55% by mass, and the total amount of the polymer block A and the polymer block B Item 2. The pressure-sensitive adhesive composition according to Item 1, wherein the mass ratio (A: B) to the total amount of is within the range of 5:95 to 30:70.
Item 3.
A base material layer;
The surface protection film which has an adhesive layer which consists of the adhesive composition of the said claim | item 1 or 2 arrange | positioned on one main surface of the said base material layer.

The pressure-sensitive adhesive composition of the present invention makes it possible to produce a surface protective film in which the progress of adhesion is suppressed. Furthermore, one aspect of the pressure-sensitive adhesive composition of the present invention enables the production of a surface protective film having excellent developability.

In the surface protective film of the present invention, the adhesion progress is suppressed. Furthermore, one aspect of the surface protective film of the present invention has excellent developability.

It is a photograph which shows a stop mark (comparative example 2).

1. Definition of Symbols in the Specification Unless otherwise specified, the symbol “to” used to represent a numerical range in this specification is intended to include the numerical values at both ends unless otherwise specified. It is done.

In the present specification, the “content” of the repeating unit of the polymer refers to a mass ratio in terms of the monomer from which the repeating unit is derived (that is, the above-described mass relative to the mass of all monomers for forming the polymer). It means the ratio (mass%) of the mass of the monomer from which the repeating unit is derived. Here, the “mass of all monomers for forming the polymer” approximates the mass of the polymer.

Similarly, in the present specification, the “content” of the repeating unit of the polymer block is the mass ratio converted to the monomer from which the repeating unit is derived (that is, the total monomer for forming the polymer block). The ratio of the mass of the monomer from which the repeating unit is derived to (mass%). Here, the “mass of all monomers for forming the polymer block” approximates the mass of the polymer block.

Specifically, the terms used in the present specification: “total aromatic alkenyl compound unit content of the copolymers (i) and (ii)” (St (A + B)), “in the total polymer block A “Aromatic alkenyl compound unit content” (St (A)), “Aromatic alkenyl compound unit content in all polymer blocks B” (St (B)), and “Aromatic alkenyl compound unit content in the entire polymer block B” "(St (b)) represents a numerical value defined by the following mathematical formula. The terms “all polymer blocks A” and “all polymer blocks B” used in this specification are “all polymer blocks in the polymers (i) and (ii)” unless otherwise specified. A ”and“ all polymer blocks B in polymers (i) and (ii) ”. Such aromatic alkenyl compound unit content is determined by ¹ H-NMR. Such aromatic alkenyl compound unit content can also be determined by infrared spectroscopy, and a value almost equivalent to ¹ H-NMR can be obtained.

“Vinyl bond content” in the present specification means the total content of 1,2-vinyl bonds and 3,4-vinyl bonds calculated by the Morello method using an infrared absorption spectrum method. The vinyl bond content of the hydrogenated product means the vinyl bond content of the polymer before hydrogenation corresponding to this.

The “vinyl bond content of the conjugated diene unit” in the present specification means a vinyl bond content of a portion derived from a conjugated diene compound (monomer).
2. Adhesive composition The adhesive composition of the present invention contains copolymers (i) and (ii) which will be described in detail later. The copolymers (i) and (ii) each contain both polymer blocks A and B described later.

In the pressure-sensitive adhesive composition of the present invention, the lower limit of the mass ratio (A: B) between the total amount of the polymer block A and the total amount of the polymer block B contained in the polymers (i) and (ii) is sufficient. From the viewpoint of obtaining a surface protective film having a holding force (a force that resists displacement), the ratio is preferably 5:95, more preferably 10:90. On the other hand, the upper limit of the ratio (A: B) is preferably 30:70 from the standpoint of obtaining a surface protection film having good followability to the unevenness of the adherend surface and high reliability of the adherend surface protection. More preferably, it is 25:75. The ratio (A: B) is preferably in the range of 5:95 to 30:70, more preferably in the range of 10:90 to 25:75.
2.1. Polymer block A
The polymer block A is a polymer block mainly composed of aromatic alkenyl compound units.

The “aromatic alkenyl compound unit” is a repeating unit derived from an aromatic alkenyl compound. Examples of the aromatic alkenyl compound include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, vinylnaphthalene, vinylanthracene, N, N And -diethyl-p-aminoethylstyrene and vinylpyridine. Among them, the “aromatic alkenyl compound unit” is preferably a styrene unit because the raw materials are industrially easily available.

The polymer block A needs to contain an aromatic alkenyl compound unit as a main repeating unit. Specifically, the aromatic alkenyl compound unit content is 80% by mass or more.
When the aromatic alkenyl compound unit content is thus high, the thermoplasticity of the pressure-sensitive adhesive composition can be improved, and the pressure-sensitive adhesive composition can be easily recycled. The polymer block A may contain a repeating unit other than the aromatic alkenyl compound unit within a range of less than 20% by mass. Examples of such a repeating unit include a repeating unit derived from a compound copolymerizable with an aromatic alkenyl compound, such as a repeating unit derived from a conjugated diene compound or a (meth) acrylic acid ester compound. . Of these, 1,3-butadiene and isoprene are preferred because of their high copolymerizability with aromatic alkenyl compounds. Such repeating units may be one kind or two or more kinds.
2.2. Polymer block B
The polymer block B is a polymer block containing conjugated diene units and aromatic alkenyl compound units randomly.

Here, “randomly” is interpreted in a broad sense, and a certain statistical law in which the chain distribution of conjugated diene units and aromatic alkenyl compound units is obtained by simultaneously polymerizing mixed conjugated diene and aromatic alkenyl compounds. Means you are in a state of following

The polymer block B is preferably mainly composed of a conjugated diene unit and an aromatic alkenyl compound unit from the viewpoint of exerting the effects of the present invention. Specifically, the total content of the conjugated diene unit and the aromatic alkenyl compound unit in the polymer block B is preferably 65% by mass or more, more preferably 80%, based on the mass of the total polymer block B. It is at least mass%.

The “conjugated diene compound unit” constituting the “polymer block B” is a repeating unit derived from a conjugated diene compound. Examples of the “conjugated diene compound” include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-octadiene, 1,3- Hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, chloroprene, etc. can be mentioned, among others, 1,3-butadiene, etc. Is preferred.

Examples of the “conjugated diene compound unit” include repeating units such as 1,4-butadiene, 1,2-butadiene, 1,2-isoprene, 1,4-isoprene, and 3,4-isoprene. Of these, repeating units such as 1,4-butadiene and 1,2-butadiene are preferred. As will be apparent to those skilled in the art, the suffix here (eg, 1,4-) indicates the reaction mode of the polymerization reaction.

The vinyl bond content of the conjugated diene unit in the polymer block B is in the range of 70 to 85% by mass, more preferably in the range of 75 to 85% by mass. When the content is 70% by mass or more, a surface protective film in which adhesion progress is suppressed can be obtained. On the other hand, when the content is 85% by mass or less, a surface protective film having sufficient adhesive strength can be obtained.

The lower limit of the aromatic alkenyl compound unit content (St (b)) of the entire polymer block B is preferably 10% by mass, more preferably 20% by mass, from the viewpoint of obtaining a surface protective film having excellent developability. More preferably, it is 30% by mass. On the other hand, the upper limit of the content (St (b)) is preferably 40% by mass from the viewpoint of obtaining a surface protective film having sufficient adhesive strength. The content (St (b)) is preferably in the range of 10 to 40% by mass, more preferably in the range of 15 to 40% by mass, and still more preferably in the range of 20 to 40% by mass. .

The polymer block B may also contain a repeating unit other than the conjugated diene compound unit and the aromatic alkenyl compound unit as long as the effects of the present invention are not lost. Examples of such a repeating unit include propylene, 2-methyl-2-butylene, 3-methyl-1-butylene, 2-methyl-1-butylene and the like. The content of such repeating units is usually 10% by mass or less, preferably 5% by mass or less, based on the total monomer unit mass in the total polymer block B.
2.3. Copolymer composition As described above, the pressure-sensitive adhesive composition of the present invention contains a copolymer composition comprising the copolymers (i) and (ii). In the present specification, the “copolymer composition comprising the copolymers (i) and (ii)” may be simply referred to as “copolymer composition”. The copolymers (i) and (ii) will be described in detail later.

The lower limit of the mass ratio ((i) :( ii)) between the copolymer (i) and the copolymer (ii) is preferably 10:90 from the viewpoint of obtaining a surface protective film having sufficient adhesive force. is there. On the other hand, the upper limit of the ratio ((i) :( ii)) is preferably 70:30 from the viewpoint of obtaining a surface protective film having excellent developability. The ratio ((i) :( ii)) is preferably in the range of 10:90 to 70:30.

The aromatic alkenyl compound unit content (St (B)) in the total polymer block B based on the total monomer mass of the copolymers (i) and (ii) is in the range of 15 to 35% by mass, preferably Is in the range of 25-35% by weight. When the content (St (B)) is 15% by mass or more, a surface protective film having excellent developability can be obtained. On the other hand, when the content (St (B)) is 35% by mass or less, a surface protective film having sufficient adhesive force can be obtained.

In the pressure-sensitive adhesive composition of the present invention, the lower limit of the aromatic alkenyl compound unit content (St (A + B)) in the polymers (i) and (ii) has excellent developability, and the pressure-sensitive adhesive progress is suppressed. From the viewpoint of obtaining a surface protective film, it is preferably 30% by mass, more preferably 35% by mass, and still more preferably 40% by mass. On the other hand, the upper limit of the content (St (A + B)) is preferably 50% by mass from the viewpoint of obtaining a surface protective film having sufficient adhesive strength. The content (St (A + B)) is preferably in the range of 30 to 50% by mass, more preferably 35 to 50% by mass, and still more preferably 40 to 50% by mass.

In the mixture of copolymer (i) and copolymer (ii), copolymer (i) and copolymer (ii) are each a hydrogenated product. In the hydrogenated product, 80% or more, preferably 90% or more, more preferably 95% or more (eg, about 98%) of the double bond (unsaturated bond) derived from the conjugated diene monomer as a whole mixture, Hydrogenated to saturated bonds.

The molecular weight of the mixture of copolymers (i) and (ii) is not particularly limited, but the mass average molecular weight is preferably 30,000 to 500,000, more preferably 80,000 to 300,000, It is preferably 100,000 to 250,000, particularly preferably 100,000 to 200,000. If the mass average molecular weight is too small, industrial productivity may deteriorate. On the other hand, if the mass average molecular weight is too large, the processability may deteriorate.
2.3.1. Copolymer (i)
Copolymer (i) comprises polymer blocks A and B as described above and has the general formula:
[AB] _n
(Where
A represents polymer block A,
B represents the polymer block B, and n represents an integer of 1 to 3. )
Or a hydrogenated product thereof.

In the copolymer (i), when two or more polymer blocks A or B are present, the two or more polymer blocks A or B may be the same or different, preferably Each is the same.

In the general formula [AB] _n , n represents an integer of 1 to 3. Therefore, the structure represented by the general formula [AB] _n is AB, ABAB, or ABABABAB. When n is within this range, the industrial productivity of the block copolymer represented by the general formula or a hydrogenated product thereof is improved. Furthermore, n is preferably 1 or 2 and particularly preferably 1 from the viewpoint of appropriate adhesive strength of the adhesive layer.

The lower limit of the content of the aromatic alkenyl compound unit in the copolymer (i) is preferably 30% by mass, more preferably 33%, from the viewpoint of obtaining a surface protective film having sufficient holding power (resistance to displacement). % By mass. On the other hand, the upper limit of the content is preferably 50% by mass, more preferably from the viewpoint of obtaining a surface protection film having good followability to the unevenness of the adherend surface and high reliability of the adherend surface protection. Is 45% by weight. The aromatic alkenyl compound unit content of the copolymer (i) is preferably in the range of 30 to 50% by mass, more preferably in the range of 33 to 45% by mass.

The molecular weight of the copolymer (i) is not particularly limited, but the mass average molecular weight is preferably 30,000 to 400,000, more preferably 30,000 to 300,000, and still more preferably 50,000 to 25 And particularly preferably from 50,000 to 200,000. If the mass average molecular weight is too small, industrial productivity may deteriorate. On the other hand, if the mass average molecular weight is too large, the processability may deteriorate.

The copolymer (i) in the pressure-sensitive adhesive composition of the present invention can be one kind or a mixture of two or more kinds, but preferably one kind. Here, whether or not the polymer is one type is determined according to common general technical knowledge in the technical field to which the present invention belongs. That is, for example, since it is common technical knowledge that the degree of polymerization or the molecular weight of the polymer has a certain variation, the copolymers (i) that differ only in the degree of polymerization and the molecular weight within the range of the certain variation are of the same type.

The copolymer (i) is preferably a hydrogenated product. In the hydrogenated product, 80% or more, preferably 90% or more, more preferably 95% or more (eg, about 98%) of the double bond (unsaturated bond) derived from the conjugated diene monomer is hydrogenated. It is a saturated bond.
2.3.2. Copolymer (ii)
Copolymer (ii) includes polymer blocks A and B as described above, and has the general formula:
(AB) _x -Y
(Where
x represents an integer of 2 or more,
Y represents a coupling agent residue, and other symbols are as defined above. )
Or a hydrogenated product thereof.

In the copolymer (ii), when two or more polymer blocks A or B are present, the two or more polymer blocks A or B may be the same or different, preferably Each is the same.

As is clear from the above general formula, the copolymer (ii) has a polymer block A at all molecular ends.

The terminal polymer block A preferably accounts for 2% by mass or more of the entire copolymer (ii) from the viewpoint of reliably exhibiting the effect of the polymer block A. Even if the terminal of some of the copolymers (ii) has a structure of -B, the content of the terminal polymer block B is less than 2% by mass of the whole copolymer (ii). Can exert the same effect as that of the polymer block A at the end. That is, the structure can be regarded as having the polymer block A at the end.

A structure represented by the general formula (AB) _x -Y (wherein _x represents an integer of 2 or more, Y represents a coupling agent residue, and other symbols are as defined above). In other words, the copolymer having has a structure in which the copolymer (i) is coupled by Y. When x is 2, it can be considered that the copolymer is substantially a triblock polymer (ABA). When x is 3 or more, the copolymer is a so-called star polymer. x is preferably 2 to 4 from the viewpoint of suppressing side reactions during the production of the copolymer and controlling the physical properties of the copolymer.

The lower limit of the content of the aromatic alkenyl compound unit in the copolymer (ii) is preferably 30% by mass, more preferably 33% from the viewpoint of obtaining a surface protective film having sufficient holding power (resistance to displacement). % By mass. On the other hand, the upper limit of the content is preferably 50% by mass, more preferably from the viewpoint of obtaining a surface protection film having good followability to the unevenness of the adherend surface and high reliability of the adherend surface protection. Is 45% by weight. The aromatic alkenyl compound unit content of the copolymer (ii) is preferably in the range of 30 to 50% by mass, and more preferably in the range of 33 to 45% by mass.

The molecular weight of the copolymer (ii) is not particularly limited, but the mass average molecular weight is preferably 50,000 to 500,000, more preferably 80,000 to 300,000, and still more preferably 100,000 to 250,000. Particularly preferred is 100,000 to 200,000. If the mass average molecular weight is too small, industrial productivity may deteriorate. On the other hand, if the mass average molecular weight is too large, the processability may deteriorate.

The copolymer (ii) can be used alone or in combination of two or more.

The copolymer (ii) is preferably a hydrogenated product. In the hydrogenated product, 80% or more, preferably 90% or more, more preferably 95% or more (eg, about 98%) of the double bond (unsaturated bond) derived from the conjugated diene monomer is hydrogenated. It is a saturated bond.
2.3.3. Method for Producing Copolymer Composition The copolymer composition can be obtained, for example, by optionally hydrogenating a mixture of copolymers (I) and (II) described later. Alternatively, the copolymer composition can be obtained by, for example, using the copolymers (i) and (ii) obtained by hydrogenating each of the copolymers (I) and (II) as desired. Can also be obtained by mixing. In the copolymer composition, both the copolymers (i) and (ii) are preferably hydrogenated products.

The copolymer (I) contains polymer blocks A ′ and B ′ described later, and has the general formula:
[A'-B '] _n
(Where
A ′ represents polymer block A ′;
B ′ represents a polymer block B ′, and n represents an integer of 1 to 3. )
It has the structure represented by these.

Copolymer (II) comprises polymer blocks A ′ and B ′ described below, and has the general formula:
(A'-B ') _x -Y
(Where
x represents an integer of 2 or more,
Y represents a coupling agent residue, and other symbols are as defined above. )
And the vinyl bond content of all conjugated diene compound units in the polymer block B ′ is in the range of 70 to 85% by mass.

The polymer block A ′ is a polymer block mainly composed of aromatic alkenyl compound units.

The polymer block B ′ is a polymer block containing a block containing a conjugated diene compound unit and an aromatic alkenyl compound unit.

Copolymers (I) and (II) can each be produced by block polymerization.

A mixture of the copolymers (I) and (II) is obtained by mixing the obtained copolymers (I) and (II).

Alternatively, the mixture of copolymers (I) and (II) can also be obtained by the following method (coupling method). In the coupling method, copolymers (I) and (II) can be synthesized in one pot, so that the production process is simple, the production cost can be reduced, and the type and amount of coupling agent. This is preferable because the ratio of the copolymers (I) and (II) can be controlled.

The coupling method is
First step: synthesizing a copolymer having a structure of [A′-B ′] by block polymerization;
Second step: A part of the copolymer having the structure of [A′-B ′] is converted into a coupling agent YZ _x (where “Y” is a coupling agent residue and “Z” is elimination) A group “x” represents an integer of 2 or more), and a copolymer having a structure of {[A′-B ′] _x —Y} is synthesized.

The coupling agent residue represented by Y is specified corresponding to the coupling agent used in the production of the block copolymer represented by the general formula or a hydrogenated product thereof.

Examples of the coupling agent include halogens such as methyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, butyltrichlorosilane, tetrachlorosilane, dipromoethane, tetrachlorotin, butyltrichlorotin, tetrachlorogermanium, and bis (trichlorosilyl) ethane. Compounds; epoxy compounds such as epoxidized soybean oil; carbonyl compounds such as diethyl adipate, dimethyl adipate, dimethyl terephthalic acid and diethyl terephthalic acid; polyvinyl compounds such as divinylbenzene; polyisocyanates; Of these, methyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane are preferred because they are easily industrially available and have high reactivity.

Hydrogenation may be performed by a method of supplying hydrogen gas in the presence of a hydrogenation catalyst, for example.

As the hydrogenation catalyst, a compound containing any one of Group Ib, IVb, Vb, VIb, VIIb, and Group VIII metals can be used. Examples thereof include compounds containing Ti, V, Co, Ni, Zr, Ru, Rh, Pd, Hf, Re, and Pt atoms. Specifically, metallocene compounds containing Ti, Zr, Hf, Co, Ni, Rh, Ru, etc .; or metals such as Pd, Ni, Pt, Rh, Ru, etc. are carbon, silica, alumina, diatomaceous earth, base A supported heterogeneous catalyst supported on a carrier such as a conductive carbon can be used.

Specific examples of the metallocene-based compound include a Kaminsky catalyst having two ligands in which hydrogen on the cyclopentadienyl ring (Cp ring) or Cp ring is substituted with an alkyl group, and ansa type metallocene. Examples thereof include a catalyst, a non-crosslinked half metallocene catalyst, and a crosslinked half metallocene catalyst. Specific examples include JP-A-1-275605, JP-A-5-271326, JP-A-5-271325, JP-A-5-222115, JP-A-11-292924, and JP-A-11-292924. JP 2000-37632 A, JP 59-133203 A, JP 63-5401 A, JP 62-218403 A, JP 7-90017 A, JP 43-19960 A, The catalyst described in Japanese Patent Publication No. 47-40473 can be given. These various catalysts can be used alone or in combination of two or more.

Usually, 80% or more, preferably 90% or more, more preferably 95% or more (eg, about 98%) of the double bond derived from the conjugated diene compound unit is hydrogenated.

Here, the hydrogenation ratio (hydrogenation rate) is a hydrogenation rate calculated from a 270 MHz, ¹ H-NMR spectrum using carbon tetrachloride as a solvent.
2.4. Other components In addition to the copolymers (i) and (ii), the pressure-sensitive adhesive composition includes a tackifier, a styrenic block phase reinforcing agent, a softening agent, an antioxidant, Generally used for pressure-sensitive adhesive compositions such as light stabilizers, ultraviolet absorbers, fillers, pigments, adhesion promoters, olefin resins, silicone polymers, liquid acrylic copolymers, phosphate ester compounds, etc. You may contain an additive suitably.

The tackifier can be used, for example, for the purpose of further suppressing the generation of pressure-sensitive adhesive layer residues. The tackifier means a material that is compatible with the rubber layer that is a soft segment and can control the adhesive force. “Compatible” means a state in which the tan δ peak temperature of the mixture obtained by adding a tackifier to the copolymer composition is different from the tan δ peak temperature of the copolymer composition. Say. In the present specification, “tan δ peak temperature” means a temperature at which tan δ is maximized.

The tackifier is not particularly limited, and examples thereof include petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymers, and alicyclic copolymers; coumarone-indene series. Resins; terpene resins; terpene-phenol resins; rosin resins such as polymerized rosins; (alkyl) phenol resins; xylene resins; or hydrogenated products thereof, especially those commonly used for adhesives Can be used without restriction. A tackifier having a softening point in the range of 90 to 140 ° C. is preferable. Moreover, in order to improve peelability and weather resistance, it is preferable to use a hydrogenated type tackifier. These tackifiers may be used alone or in combination of two or more. Moreover, you may use the commercially available tackifier which is a mixture containing the above tackifiers in combination with an olefin resin.

When a tackifier is used, the upper limit of the amount used is, for example, preferably about 1 to 50 parts by mass, more preferably about 1 to 40 parts by mass with respect to 100 parts by mass of the copolymer composition.

The styrenic block phase reinforcing agent is an agent that reinforces the island phase of the sea-island structure formed by the aromatic alkenyl block copolymer. It can be used for the purpose of improving and further suppressing the occurrence of adhesive residue pressure-sensitive adhesive layer residue when the surface protective film is peeled off from the adherend.

Examples of the styrenic block phase reinforcing agent include, as monomer units, styrene and α-methylstyrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene, tert-butylstyrene, p-ethylstyrene, divinylbenzene. Styrenic compounds such as These can be used alone or in combination of two or more. That is, the styrenic block phase reinforcing agent can be obtained by polymerizing these monomers. In the case of a copolymer composed of two or more types of monomers, it may be a block copolymer or a random copolymer. Among them, the styrenic block phase reinforcing agent preferably has a softening point of about 100 ° C. or higher, and more preferably 150 ° C. or higher. Specifically, trade names “ENDEX 155” (softening point 155 ° C.), “ENDEX 160” (softening point 160 ° C.) manufactured by Eastman Chemical Co., Ltd. are preferably used.

When using a styrenic block phase reinforcing agent, the amount used is, for example, preferably about 1 to 40 parts by weight, more preferably about 1 to 30 parts by weight with respect to 100 parts by weight of the copolymer composition. It is.

The softener can be used, for example, for the purpose of further improving the adhesive strength of the adhesive layer. Examples of the softener include low molecular weight diene polymer, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene, paraffinic process oil, naphthenic process oil, aromatic process oil, castor oil, tall oil, natural oil, What is generally used for an adhesive, such as liquid polyisobutylene resin, polybutene, or a hydrogenated product thereof, can be used without particular limitation.

The antioxidant is not particularly limited, and examples thereof include phenol-based (monophenol-based, bisphenol-based, polymer-type phenol-based) antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

The light stabilizer is not particularly limited, and examples thereof include hindered amine compounds.

The ultraviolet absorber is not particularly limited, and examples thereof include a salicylic acid ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a cyanoacrylate ultraviolet absorber.

Examples of the filler include calcium carbonate, magnesium carbonate, silica, zinc oxide, and titanium oxide.

Examples of the anti-adhesive agent include fatty acid amides, polyethyleneimine long-chain alkyl grafts, soybean oil-modified alkyd resins (for example, Arakawa Chemical Industries, trade name “Arachid 251”, etc.), tall oil-modified alkyd resins (for example, Arakawa Chemical Industries, Ltd., trade name “Arachid 6300” and the like.

These additives can be used alone or in combination of two or more.
2.5. Production Method The pressure-sensitive adhesive composition of the present invention is produced by mixing the copolymers (I) and (II) and additives used as necessary in a conventional manner.
3. Surface protective film The surface protective film of the present invention is
A base material layer;
A pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present invention, which is disposed on one main surface of the base material layer.
3.1. Base material layer The base material layer in the surface protective film of the present invention is preferably a polyolefin base material layer.

Examples of the “polyolefin” include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Examples thereof include ethylene, methyl acrylate copolymer, ethylene n-butyl acrylate copolymer, and polypropylene (homopolymer, random copolymer, block copolymer). The “polyolefin” may be a polyolefin having a substituent. These can be used alone or in combination of two or more.

The base material layer may further contain a resin other than polyolefin. Moreover, a base material layer may be formed from polyolefin, the resin other than polyolefin depending on necessity, and the polyolefin base material layer and / or surface protection film edge material which were produced in the manufacture process of a surface protection film.

The substrate layer may be a single layer or a layer having two or more multilayer structures having different compositions.

When the base material layer has a layer formed from polyolefin, a resin other than polyolefin as required, and a polyolefin base material layer and / or a surface protective film edge material produced in the process of producing the surface protective film, this layer is an adhesive layer. Adjacent to is preferable.

The thickness of the base material layer can be appropriately adjusted depending on the use of the surface protective film. Usually, a thickness of about 10 to 100 μm is suitable.

Thereby, even when the surface protective film of this embodiment is stuck on the surface of the prism sheet and stored in a stacked manner, damage to the lens portion (prism) of the prism sheet can be made difficult to occur. It can be suitably used for protection.

In particular, when the surface roughness of the back surface of the base material layer, the average height of the swell motif, and the average length of the swell motif are within the predetermined range, when a plurality of sheets having a surface protective film attached thereto are stored in layers. Even if there is a minute entrapment foreign matter, the minute entrapment foreign matter can enter the waviness valley of the surface, so the stress concentrated on the lens part is reduced compared to when the surface is smooth It is thought that it can be done.
3.2. Adhesive layer The said adhesive layer consists of an adhesive composition of this invention.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but if the pressure-sensitive adhesive composition of the present invention is used, sufficient adhesive strength can be obtained even with a relatively thin pressure-sensitive adhesive layer, for example, usually about 0.5 to 20 μm, preferably 1 It is ˜15 μm, more preferably 2 to 10 μm. By reducing the thickness of the adhesive layer, the manufacturing cost can be reduced and the progress of the adhesive can be suppressed.
3.3. Manufacturing Method The surface protective film of the present invention is prepared by, for example, manufacturing a base sheet (base layer) by extrusion, and then applying or spraying a liquid obtained by melting or dissolving the pressure-sensitive adhesive composition on the base sheet. A method of bonding a base material sheet obtained by an inflation method and a pressure-sensitive adhesive sheet; or a method of co-extruding a base material and the pressure-sensitive adhesive composition using a T die having a multilayer manifold. Especially, since the multilayer sheet | seat with which the base material layer and the adhesion layer contact | adhered is obtained, the method of manufacturing by coextrusion is preferable. A liquid obtained by melting or dissolving the pressure-sensitive adhesive composition of the present invention is also included in the pressure-sensitive adhesive composition of the present invention.
4. Application The surface protective film of the present invention can be suitably used for surface protection of various products (parts). Among them, it can be suitably used for an uneven substrate such as an optical plate and a diffusion film, but is not limited thereto, and for example, it can be used for surface protection of a sheet having a smooth surface. it can.

The material constituting the sheet to be the adherend is not particularly limited, and examples thereof include translucent resins such as acrylic resins and polycarbonates.

Hereinafter, although the surface protection film of this invention is demonstrated in detail based on an Example, this invention is not limited to a following example.
(Production of copolymer composition)
(Synthesis of polymer block A)
A nitrogen-substituted reaction vessel is charged with 500 parts by mass of degassed and dehydrated cyclohexane, 15 parts by mass of styrene and 5 parts by mass of tetrahydrofuran, and 0.13 parts by mass of n-butyllithium is added at a polymerization start temperature of 40 ° C. Then, temperature rising polymerization was performed.
(Synthesis of polymer block B)
After the polymerization conversion rate of the polymer A reached approximately 100%, the reaction solution was cooled to 15 ° C., and then 55 parts by mass of 1,3-butadiene and 30 parts by mass of styrene were added, followed by further temperature rising polymerization. .
(Synthesis of copolymers (i) and (ii))
After the polymerization conversion rate reached almost 100%, 0.06 parts by mass of methyldichlorosilane was added as a coupling agent to carry out a coupling reaction. After the coupling reaction was completed, the gas was left for 10 minutes while supplying hydrogen gas at a pressure of 0.4 MPa-Gauge. A partially extracted polymer had a vinyl bond content of the conjugated diene unit in the polymer block B of 73%, a mass average molecular weight of about 160,000, and a coupling rate of 40%.

Thereafter, 0.03 part by mass of diethylaluminum chloride and 0.06 part by mass of bis (cyclopentadienyl) titanium furfuryloxychloride were added to the reaction vessel and stirred. The hydrogenation reaction was started at a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80 ° C. When the absorption of hydrogen was completed, the reaction solution was returned to room temperature and normal pressure, and then extracted from the reaction vessel. A copolymer composition composed of the union (i) and (ii) was obtained (Synthesis Example 1 in Table 1).

Hereinafter, the desired copolymer compositions were obtained in the same manner using raw materials having different composition ratios (Synthesis Examples 1 to 8 in Table 1). The properties of these copolymer compositions are shown in Table 1. In the table, “wt%” represents mass%. The vinyl bond content of the conjugated diene unit in the polymer block B is abbreviated as “vinyl bond content”.

(Examples 1 to 5, Comparative Examples 1 to 3)
Polypropylene (J715M manufactured by Prime Polymer Co., Ltd.) was used as the base material, and the base material and each copolymer composition obtained by the above synthesis methods were coextruded by the T-die method. A surface protection film of Examples 1 to 5 and Comparative Examples 1 to 3 in which a base material layer and an adhesive layer having a thickness of 6 μm were laminated and integrated, and wound on a paper core having an inner diameter of 3 inches I got a round.
(Evaluation test)
The following items (1) to (4) were evaluated for each surface protective film obtained as described above. The results are shown in Table 2.

(1) Film forming property The appearance of each surface protective film formed by coextrusion as described above was visually evaluated. The symbol “◯” in the table indicates that there was no problem in appearance.

(2) Initial adhesive strength Each surface protective film was placed on an acrylic plate (surface roughness of 0.10 μm or less) and a SUS plate whose surface was polished so that the surface roughness was 0.30 to 0.80 μm at room temperature of 23 ° C. And in the environment of relative humidity 50%, it stuck by the speed | rate of 5.9 * 10 < ⁵ > Pa and the speed | rate of 30 mm / min, respectively using the desktop laminator. After leaving in this environment for 30 minutes, according to the method of JIS Z0237, the 180 ° peel-off adhesive strength of these films (25 mm width) was measured at a speed of 300 mm / min, and this was regarded as the initial adhesive strength. .

At this time, the surfaces of the acrylic plate and the SUS plate were visually observed, and it was confirmed that there was no adhesive layer residue on the acrylic plate surface.

(3) Adhesive strength over time Using a table laminator, each surface protective film was placed on the surface of the acrylic plate and SUS plate used in the initial adhesive strength evaluation of (2) above in an environment of room temperature 23 ° C. and relative humidity 50%. And a pressure of 5.9 × 10 ⁵ Pa and a speed of 30 mm / min. Thereafter, the film was left at 60 ° C. or 80 ° C. for 30 minutes, and then left at room temperature for 30 minutes. Then, according to the method of JIS Z0237, these films (25 mm width) were peeled off by 180 degrees and the adhesive strength was 300 mm. Measured at a rate of / min.

The peel adhesive force measured in this way was defined as the time-dependent adhesive force, and the change ratio (adhesion progress ratio) of the time-dependent adhesive force was calculated from the initial adhesive force by the following equation.
Change ratio (adhesion progress ratio) = (adhesive force over time / initial adhesive force)
<Criteria>
Change ratio (adhesion progress ratio)
◎ (excellent): Less than 1.5 ○ (good): 1.5 or more, 2 or less × (defect): more than 2 (4) Adhesive strength of the back surface Each surface protective film of Examples and Comparative Examples is a table laminator. The film was attached under conditions of pressure 5.9 × 10 ⁵ Pa and speed 30 m / min, and left in an environment of room temperature and 80 ° C. for 60 minutes.

After taking out from an environment of 80 ° C. to room temperature and leaving it for 30 minutes, in accordance with JIS Z0237, 180 degree peel strength at 25 mm width was measured at a speed of 15 m / min.

(5) Evaluation of stop mark Each surface protective film of Examples and Comparative Examples was pasted with a table laminator under the conditions of pressure 5.9 × 10 ⁵ Pa and speed 30 m / min, and left in an environment of 80 ° C. for 60 minutes. did. After taking this out to room temperature and leaving it for 30 minutes, according to JIS Z0237, 180 degree peel strength in 25 mm width was peeled at the speed of 15 m / min, and the presence or absence of the stop mark was evaluated.

Thereafter, the peeled surface protective film was attached to a prism sheet (prism pitch 50 μm, height 25 μm) made of acrylic resin having a thickness of 60 μm under conditions of pressure 5.9 × 10 ⁵ Pa and speed 30 m / min, After leaving for 30 minutes in an environment of 60 ° C. and peeling off the surface protective film, the presence or absence of transfer of the stop mark to the prism sheet was visually evaluated. In addition, the photograph of the surface protection film of the comparative example 2 is published for the illustration of a stop mark.
<Criteria>
◎ (excellent): Stop mark was not observed on the film and was not transferred to the prism sheet. ○ (Good): Stop mark was observed on the film but was not transferred to the prism sheet. Stop mark was observed and transferred to prism sheet

The pressure-sensitive adhesive composition of the present invention is suitably used for the pressure-sensitive adhesive layer of a surface protective film such as a diffusion film. The surface protective film of this invention is used suitably for surface protection, such as a diffusion film.

Claims

Copolymer (i): including the following polymer block A and the following polymer block B,
Formula [AB] n
(In the formula, A represents the polymer block A, B represents the polymer block B, and n represents an integer of 1 to 3.
)
A copolymer (I) having a structure represented by the formula:
Copolymer (ii): including the following polymer block A and the following polymer block B,
General formula ABA (the symbols in the formula are as defined above) or general formula (AB) x -Y (wherein x represents an integer of 1 or more and Y is a coupling agent) Residues and other symbols are as defined above.)
A copolymer (II) having a structure represented by the formula (II) or a hydrogenated product thereof:
The vinyl bond content of the conjugated diene unit in the polymer block B is in the range of 70 to 85%, and
Adhesive having an aromatic alkenyl compound unit content (St (B)) in the range of 15 to 35% by mass in the total polymer block B based on the total monomer mass of the copolymers (i) and (ii) Composition.
Polymer block A:
Polymer block in which aromatic alkenyl compound units are continuous and mainly composed of aromatic alkenyl compound units Polymer block B:
Aromatic alkenyl-conjugated diene copolymer block containing conjugated diene units and aromatic alkenyl compound units randomly
The aromatic alkenyl compound unit content (St (b)) of the entire polymer block B is in the range of 10 to 40% by mass,
The total aromatic alkenyl compound unit content (St (A + B)) of the copolymers (i) and (ii) is in the range of 35 to 55% by mass, and the total amount of the polymer block A and the polymer block B 2. The pressure-sensitive adhesive composition according to claim 1, wherein the mass ratio (A: B) to the total amount is in the range of 5:95 to 30:70.
A base material layer;
The surface protection film which has an adhesive layer which consists of an adhesive composition of Claim 1 or 2 arrange | positioned on one main surface of the said base material layer.