JP6914694B2 - Stretched film - Google Patents

Description

The present invention relates to stretched films, preferably stretched films useful as optical materials.

Acrylic resins have high transparency and have been conventionally used as materials for optical films. Among them, an acrylic resin having a ring structure in the main chain can improve heat resistance while maintaining transparency (Patent Document 1 and the like). However, by increasing the heat resistance, the resin itself becomes hard and brittle, and the mechanical properties such as folding resistance tend to decrease during film processing. For example, Patent Document 2 points out that the flexibility of an acrylic resin having glutarimide in the main chain is insufficient. Therefore, in Patent Document 2, in order to improve the lack of flexibility of the acrylic resin, a block copolymer composed of an acrylic acid ester polymer block (B1) and a methacrylic acid ester polymer block (B2) is blended. is doing. Specifically, a butyl acrylate polymer block is used as the acrylate polymer block (B1).

Patent Documents 3 and 4 describe a block copolymer (B) having a polymer block (a) composed of a (meth) acrylic acid alkyl ester unit and a polymer block (b) composed of a conjugated diene compound unit. A (meth) acrylic resin composition obtained by dissolving in a monomer mixture containing methyl acid acid and radically polymerizing the monomer mixture is described. Specific examples of the block copolymer (B) include a butadiene-acrylate n-butyl diblock copolymer and a polymer obtained by polymerizing 1,6-hexanediol diacrylate on the copolymer. Has been described.

Patent Document 5 describes a composition containing an acrylic block copolymer having a polymer block (A) having a glass transition temperature of 50 ° C. or higher and a polymer block (B) having a glass transition temperature of 20 ° C. or lower. The optical members to be formed are described. As the polymer block (B), specifically n-butyl block acrylate is described.

Patent Document 6 discloses a block copolymer having a methacrylic copolymer block (A) and an acrylic copolymer block (B) as an acrylic thermoplastic resin used as an optical material. As the acrylic copolymer block (B), an ethyl acrylate copolymer block is specifically disclosed, and the weight average molecular weight of the copolymer having the ethyl acrylate copolymer block is 470,000 to 500,000. Is.

Japanese Unexamined Patent Publication No. 2006-171464 Japanese Unexamined Patent Publication No. 2016-71218 Japanese Unexamined Patent Publication No. 2014-289944 International Publication No. 2014/002506 Special Table 2012-514212 Japanese Unexamined Patent Publication No. 2014-12782

However, in the stretched film containing the block copolymer, the tear strength may decrease or the haze value may increase. An object of the present invention is to provide a stretched film having a high flexibility, a tear strength, and a low haze value.

As a result of diligent studies to solve the above problems, the present inventors may control the glass transition temperature of a block copolymer having a predetermined molecular weight to produce a stretched film containing this block copolymer. We have found that the tear strength is maintained while the flexibility is increased, and the haze value is also lowered, and the present invention has been completed.
That is, the present invention is as follows.
[1] A stretched film containing a (meth) acrylic acid ester-based block copolymer, wherein the block copolymer has a polymer block (A) and a polymer block (B), and the block copolymer is used. A stretched film in which the glass transition temperature of the polymer is in the range of 80 ° C. or higher and the glass transition temperature of the block copolymer is in the range of −30 ° C. or higher and 25 ° C. or lower, and the weight average molecular weight of the block copolymer is 20,000 or more and 400,000 or less.
[2] The polymer block (A) is a polymer block containing a structural unit derived from alkyl methacrylate and / or an alkyl acrylate, and the polymer block (B) is a weight containing a structural unit derived from a methacrylic acid ester. The stretched film according to [1], which is a coalesced block.
[3] The content of the polymer block (A) containing the structural unit derived from the alkyl methacrylate and / or alkyl acrylate is 5 parts by mass or more and 90 parts by mass or less in 100 parts by mass of the block copolymer. The stretched film according to [2], wherein the block copolymer has a tensile elastic modulus of 0.5 GPa or more and 2.0 GPa or less.
[4] The stretched film according to [2] or [3], wherein the polymer block (A) containing a structural unit derived from the alkyl methacrylate and / or alkyl acrylate has a weight average molecular weight of 5,000 or more and 200,000 or less.
[5] The polymer block (A) containing structural units derived from the alkyl methacrylate and / or alkyl acrylate is described in any one of [2] to [4] containing structural units derived from two or more kinds of monomers. Stretched film.
[6] The stretched film according to any one of [1] to [5], which further contains a matrix resin.
[7] The content of the polymer block (A) containing the structural unit derived from the alkyl methacrylate and / or alkyl acrylate is 1 part by mass or more and 50 parts by mass or less in 100 parts by mass of the stretched film. Stretched film.
[8] The stretched film according to [6] or [7], wherein the content of the block copolymer is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the matrix resin.
[9] The stretched film according to any one of [1] to [8], which has a haze of 0.5% or less.
[10] The stretched film according to any one of [1] to [9], wherein the tear strength retention index measured by the following method is 0.50 or more.
[Measurement method of tear strength retention index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film are molded into a length of 120 mm, a width of 30 mm, and a thickness of 40 μm, respectively, at 200 mm / min. Perform the test at the test speed of and measure the tear strength. A tear strength Tr ₁ measured for stretched film, a ratio (Tr ₁ / Tr ₀₎ tear strength retention index and tear strength Tr ₀ measured for the stretched film of the matrix resin.
[11] The stretched film according to any one of [1] to [10], wherein the folding resistance improvement index measured by the following method is 1.1 or more.
[Measurement method of folding resistance improvement index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film were molded into a length of 90 mm, a width of 15 mm, and a thickness of 40 μm, respectively, at 23 ° C. The film is allowed to stand at 50% RH for 1 hour or more, and is reciprocally bent under the conditions of a bending angle of 135 °, a bending speed of 175 cpm, and a load of 200 g, and the number of reciprocating bends until the film is broken is measured by 5 sheets each. Folding number M ₁ the average value of the reciprocating folding number was measured for the stretched film, the average value of the reciprocating folding number was measured for the stretched film of the matrix resin as a folding number M _0, their ratio (M ₁ / M ₀ ) Is used as the folding resistance improvement index.
[12] The stretched film according to any one of [1] to [11], which has a thickness of 1 μm or more and 400 μm or less.

Since the stretched film of the present invention contains a block copolymer having a predetermined molecular weight and controlling the glass transition temperature, it is possible to maintain the tear strength while increasing the flexibility and further reduce the haze value. ..

(1) Stretched Film The stretched film of the present invention contains a (meth) acrylic acid ester-based block copolymer (hereinafter, may be referred to as "block copolymer (C)").

(1.1) Block copolymer (C)
The (meth) acrylic acid ester-based block copolymer (C) means a block copolymer containing a structural unit derived from the (meth) acrylic acid ester. The ratio of the structural unit derived from the (meth) acrylic acid ester contained in the block copolymer (C) is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 90 parts by mass or less, based on 100 parts by mass of the block copolymer (C). It is 20 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 70 parts by mass or less.

The weight average molecular weight (Mw) of the block copolymer (C) is 20,000 or more, preferably 50,000 or more, more preferably 70,000 or more, 400,000 or less, preferably 380,000 or less, and more preferably 350,000. It is as follows. By setting the weight average molecular weight (Mw) of the block copolymer (C) in an appropriate range, the haze value of the resin film can be lowered.

The number average molecular weight (Mn) of the block copolymer (C) is not particularly limited as long as the weight average molecular weight can be achieved, but is, for example, 10,000 or more, preferably 30,000 or more, and more preferably 50,000 or more. Yes, for example, 300,000 or less, preferably 200,000 or less, more preferably 180,000 or less. Controlling the number average molecular weight of the block copolymer (C) is also effective in reducing the haze value of the resin film.

The molecular weight distribution (Mw / Mn) of the block copolymer (C) is, for example, 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more, and for example, 3 or less, preferably 2.5. Below, it is more preferably 2.0 or less.

The block copolymer (C) has a glass transition temperature on the high temperature side (80 ° C. or higher) (hereinafter, may be referred to as “high Tg characteristic”) and has a specific range on the low temperature side (-30 ° C. or higher and 25 ° C. or higher). The following) is also characterized in that it has a glass transition temperature (hereinafter, it may be referred to as "low Tg characteristic"). Since the block copolymer (C) has high Tg characteristics and low Tg characteristics, the stretched film containing the block copolymer (C) improves impact resistance and flexibility while maintaining tear strength. It is possible to do.

The glass transition temperature on the low temperature side is 25 ° C. or lower, preferably 20 ° C. or lower, more preferably 15 ° C. or lower, still more preferably 10 ° C. or lower, and -30 ° C. or higher, preferably -25 ° C. or higher, more preferably −. It is 20 ° C. or higher. The glass transition temperature on the high temperature side is 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, and for example, 200 ° C. or lower, preferably 180 ° C. or lower, more preferably 170 ° C. or lower. Is.
The difference in glass transition temperature between the low temperature side and the high temperature side is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, preferably 170 ° C. or lower, more preferably 155 ° C. or lower. More preferably, it is 145 ° C. or lower.
The block copolymer (C) preferably does not have a glass transition temperature below −30 ° C.

(1.1a) Polymer block (A)
The block copolymer (C) includes a polymer block (A) (hereinafter, may be referred to as "soft segment (A)") and a polymer block (B) (hereinafter, "hard segment (B)"). (Sometimes referred to as), and by having these, it is possible to exhibit the low Tg characteristic and the high Tg characteristic.

The polymer block (A) serving as the soft segment (A) is a (meth) acrylic acid ester-based polymer block, more preferably a polymer block having a structural unit derived from alkyl methacrylate and / or alkyl acrylate. The soft segment (A) may be a homopolymer block of alkyl methacrylate and / or alkyl acrylate, or may be a copolymer block containing structural units derived from two or more types of monomers.

Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, and amyl acrylate. Isoamyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, pentadecyl acrylate are preferred.
Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, and amyl methacrylate. Isoamyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and pentadecyl methacrylate are preferred.
In the soft segment (A), these alkyl methacrylates and / or alkyl acrylates may be used alone or in combination as appropriate.

The ratio of the structural unit derived from the alkyl methacrylate and / or alkyl acrylate is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and further preferably 95 parts by mass or more in 100 parts by mass of the soft segment (A). It is preferably 100 parts by mass or less.

The soft segment (A) preferably has a unit derived from an alkyl acrylate having an alkyl group having 1 to 3 carbon atoms (hereinafter, may be referred to as “C1 to 3 acrylate”). By including the unit derived from C1 to 3 acrylates, it becomes easy to adjust the glass transition temperature of the soft segment (A) within the above range.

Examples of C1 to 3 acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate and the like, and methyl acrylate and ethyl acrylate are preferable. These C1 to 3 acrylates may be used alone or in combination as appropriate, but are preferably used alone from the viewpoint of ease of production. The C1 to 3 acrylates may be copolymerized with an alkyl acrylate other than the C1 to 3 acrylates and / or an alkyl methacrylate.

The amount of C1 to 3 acrylate is, for example, 50 parts by mass or more, preferably 70 parts by mass or more, more preferably 90 parts by mass or more, and 100 parts by mass in 100 parts by mass of all the units constituting the soft segment (A). It may be.

It is also preferable that the soft segment (A) has a unit derived from alkyl methacrylate. The inclusion of units derived from alkyl methacrylate facilitates the adjustment of the glass transition temperature of the soft segment (A) to the above range. The number of carbon atoms of the alkyl group in the alkyl acrylate is preferably 1 or more, more preferably 3 or more, still more preferably 4 or more, preferably 20 or less, more preferably 15 or less, still more preferably 8 or less, particularly preferably. It is 6 or less.

The amount of the alkyl methacrylate unit is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, and for example, 100 parts by mass or less, preferably 90 parts by mass, out of 100 parts by mass of all the units constituting the soft segment (A). It is as follows.

When the soft segment (A) contains a unit derived from an alkyl methacrylate having 1 to 2 carbon atoms (hereinafter, may be referred to as "C1 to 2 methacrylate"), the C1 to 2 methacrylate is an alkyl. It is preferable to copolymerize with an alkyl acrylate having a group having 3 or more carbon atoms (preferably 4 or more) (hereinafter, may be referred to as "acrylate of C3 or more"). In this case, the amount of the unit derived from the acrylate of C3 or more (preferably the acrylate of C4 or more) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, still more preferably 40 parts by mass, out of 100 parts by mass of the soft segment (A). It is 45 parts by mass or more, preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 55 parts by mass or less.

When the soft segment (A) contains a unit derived from an alkyl methacrylate having 3 or more carbon atoms in the alkyl group (hereinafter, may be referred to as "methacrylate of C3 or higher"), the methacrylate of C3 or higher is an alkyl acrylate. It may or may not be copolymerized with. In the case of copolymerization, the amount of the unit derived from the alkyl acrylate is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, still more preferably 45 parts by mass or more, and preferably 45 parts by mass or more, based on 100 parts by mass of the soft segment (A). Is 70 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 55 parts by mass or less.

The soft segment (A) further has a unit derived from another monomer copolymerizable with alkyl methacrylate and / or alkyl acrylate (hereinafter, may be referred to as "copolymerization monomer A"). You may.

Examples of the copolymerization monomer A include acrylic acid esters other than the alkyl acrylate, methacrylic acid esters other than the alkyl methacrylate, unsaturated carboxylic acids, aromatic vinyl compounds, olefins, conjugated diene, acrylonitrile, methacrylonitrile, and acrylamide. Examples thereof include methacrylicamide, vinyl acetate, vinylpyridine, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride and the like, preferably an acrylic acid ester having an aromatic ring, a methacrylic acid ester having an aromatic ring, an aromatic vinyl compound and the like. Aromatic monomers of. The glass transition temperature of the soft segment (A) may be adjusted to the above range by using the copolymerization monomer A. By copolymerizing the aromatic monomer, the refractive index can be adjusted and the compatibility and transparency at the time of mixing with the resin composition can be improved. As the aromatic monomer, an aromatic vinyl compound is preferable.

The acrylic acid ester as the copolymerization monomer A includes functional groups such as an acrylic acid ester having a cyclic aliphatic hydrocarbon group (cyclohexyl acrylate, isobornyl acrylate, etc.), a hydroxy group, an ether bond, an epoxy group, and an allyl group. Non-aromatic acrylic acid esters such as group-based aliphatic acrylic acid esters (2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, glycidyl acrylate, allyl acrylate, etc.); phenyl acrylate, benzyl acrylate, etc. , Acrylic acid ester having an aromatic ring such as phenoxyethyl acrylate and the like are included.

The methacrylate ester as the copolymerization monomer A includes functional groups such as a methacrylate ester having a cyclic aliphatic hydrocarbon group (cyclohexyl methacrylate, isobornyl methacrylate, etc.), a hydroxy group, an ether bond, an epoxy group, and an allyl group. Non-aromatic methacrylate esters such as group-based aliphatic methacrylate esters (2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate, glycidyl methacrylate, allyl methacrylate, etc.); phenyl methacrylate, benzyl methacrylate, etc. , Methacrylate esters having an aromatic ring, such as phenoxyethyl methacrylate, and the like are included.

Examples of the aromatic vinyl compound as the copolymerization monomer A include benzene ring-containing compounds such as styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, and α-hydroxyethylstyrene; N-vinylcarbazole and vinylpyridine. , Vinyl imidazole, compounds having an aromatic heterocycle such as vinylthiophene, and the like.
In the soft segment (A), the amount of the unit derived from the copolymerization monomer A (preferably an acrylic acid ester other than the alkyl acrylate, an aromatic monomer, etc.) is derived from alkyl methacrylate and / or alkyl acrylate. For example, it is 0 parts by mass or more, preferably 1 part by mass or more, and for example, 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less with respect to 100 parts by mass in total. ..

The weight average molecular weight (Mw) of the polymer block (A) is, for example, 5000 or more, preferably 10,000 or more, more preferably 20,000 or more, for example, from the viewpoint of mechanical properties, optical properties, and fluidity. It is 200,000 or less, preferably 150,000 or less, and more preferably 100,000 or less. The number average molecular weight (Mn) of the polymer block (A) is, for example, 3000 or more, preferably 10,000 or more, more preferably 15,000 or more, and for example, 150,000 or less, preferably 100,000 or less. It is preferably 80,000 or less. The molecular weight distribution (Mw / Mn) of the polymer block (A) is not particularly limited, but is, for example, 1.05 or more, preferably 1.1 or more, and for example, 2.5 or less, preferably 2.0 or less. More preferably, it is 1.8 or less.

The refractive index of the polymer block (A) is, for example, 1.468 or more, preferably 1.470 or more, more preferably 1.480 or more, for example 1.600 or less, preferably 1.580 or less, and more. It is preferably 1.550 or less.

(1.1b) Polymer block (B)
The polymer block (B) is introduced so that the block copolymer (C) exhibits high Tg characteristics, and constitutes a hard segment in the block copolymer (C). The constituent monomer of the polymer block (B) is not particularly limited as long as it exhibits a predetermined glass transition temperature, but is usually a homopolymer block or a copolymer block of a methacrylic ester unit. The amount of the methacrylic acid ester unit in 100 parts by mass of all the units constituting the polymer block (B) is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, and for example, 100 parts by mass or less, preferably 90 parts by mass. It is less than a part by mass.

Examples of the methacrylic acid ester from which the unit of the hard segment (B) is derived include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and sec methacrylate. -Butyl, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, methacrylic Examples thereof include benzyl acetate, phenoxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate, glycidyl methacrylate, and allyl methacrylate. Alkyl methacrylate is preferable, and in particular, alkyl methacrylate having an alkyl group having 1 to 3 carbon atoms such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and isopropyl methacrylate (hereinafter, “C1 to 3 methacrylate”). It is preferable to always contain (may be referred to as), and it is most preferable to always contain methyl methacrylate. The amount of C1 to 3 methacrylate (preferably the amount of methyl methacrylate) is, for example, 50 parts by mass or more, preferably 70 parts by mass or more, more preferably 90 parts by mass or more, and 100 parts by mass, based on 100 parts by mass of the methacrylate ester. It may be a mass part.

In the hard segment (B), examples of the monomer copolymerizable with the methacrylic acid ester (particularly C1 to 3 methacrylate) (hereinafter, may be referred to as “copolymerization monomer B”) include an acrylic acid ester. Unsaturated carboxylic acids, aromatic vinyl compounds, olefins, conjugated diene, acrylonitrile, methacrylonitrile, acrylamide, methacrylicamide, vinyl acetate, vinylpyridine, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride and the like are preferable. Examples thereof include acrylic acid esters and aromatic monomers (acrylic acid esters having an aromatic ring, methacrylic acid esters having an aromatic ring, aromatic vinyl compounds, etc., particularly aromatic vinyl compounds).

Examples of the acrylic acid ester that can be used as the copolymer monomer B include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and sec-butyl acrylate. , Tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, isobornyl acrylate, phenyl acrylate, benzyl acrylate , Phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, glycidyl acrylate, allyl acrylate and the like, preferably methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylate. Examples thereof include acrylic acid alkyl esters having an alkyl group having 1 to 4 carbon atoms (preferably an alkyl group having 1 to 3 carbon atoms) such as isopropyl, n-butyl acrylate, and isobutyl acrylate. As the aromatic vinyl compound that can be used as the copolymer monomer B, the same aromatic vinyl compounds as those exemplified as the copolymer monomer A can be used.

Examples of the aromatic monomer that can be used as the copolymer monomer B include compounds similar to the aromatic monomer that can be used as the copolymer monomer A. The preferred aromatic monomer is also the same as in the case of the copolymer monomer A. By using an aromatic monomer, the birefringence of the block copolymer (C) can be adjusted.

In the hard segment (B), the amount of the unit derived from the copolymerization monomer B (preferably acrylic acid ester, aromatic monomer, etc.) is 0, for example, with respect to 100 parts by mass of the methacrylic acid ester unit. It is by mass or more, preferably 1 part by mass or more, and is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.
The soft segment (A) contains units derived from C1-2 methacrylate and C3 or higher acrylate (preferably C4 or higher acrylate), and the hard segment (B) also contains C1-2 methacrylate and C3 or higher acrylate (preferably C3 or higher acrylate). When a unit derived from C4 or higher acrylate) is included, the amount of the unit derived from C3 or higher acrylate (preferably C4 or higher acrylate) in the hard segment (B) is preferably in 100 parts by mass of the hard segment (B). It is less than 45 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 30 parts by mass.

Further, the hard segment (B) does not have to substantially contain a unit having a ring structure (preferably a unit having a ring structure in the main chain) from the viewpoint of fluidity (for example, 5% by mass or less, particularly 0). (Mass%), from the viewpoint of heat resistance, a unit having a ring structure (preferably a unit having a ring structure in the main chain) may be substantially contained (for example, more than 5% by mass). A unit having a ring structure (preferably a unit having a ring structure in the main chain) is usually introduced into the hard segment (B) as a copolymerization unit of the methacrylic acid ester unit (particularly C1 to 3 methacrylate units). When a unit having a ring structure (preferably a unit having a ring structure in the main chain) is introduced into the block copolymer (C), the optical characteristics of the block copolymer (C) itself can be improved. Further, when the block copolymer (C) is added to a resin having a ring structure (preferably a unit having a ring structure in the main chain), compatibility with the resin can be improved. The amount of the unit having a ring structure (preferably a unit having a ring structure in the main chain) is, for example, 0 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass with respect to 100 parts by mass of the methacrylic acid ester unit. It is 5 parts by mass or more, for example, 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less.

Examples of the ring structure include a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, a maleic anhydride structure, an N-substituted maleimide structure, and the like, preferably a lactone ring structure and an N-substituted maleimide structure. These ring structures are preferably contained in the main chain. The lactone ring structure is preferably, for example, a 4-membered ring to 8-membered lactone ring structure, and more preferably a 5-membered ring or a 6-membered ring because the ring structure is excellent in stability, and is a 6-membered ring. Is most preferable. Examples of the 6-membered lactone ring structure include the structures disclosed in JP-A-2004-168882, which facilitate the introduction of the lactone ring structure, specifically, a precursor (lactone). The polymerization yield of the polymer before cyclization) is high, the lactone ring content in the cyclization condensation reaction of the precursor can be increased, and the polymer having the methyl methacrylate unit as a constituent unit can be used as the precursor. For these reasons, the structure represented by the following general formula (1) is particularly preferable.

In the above general formula (1), R ¹ , R ² and R ³ are independent of each other as a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. good.
Examples of the organic residue in the general formula (1) include carbons such as a saturated aliphatic hydrocarbon group (alkyl group, etc.) having 1 to 20 carbon atoms such as a methyl group, an ethyl group, and a propyl group, an ethenyl group, and a propenyl group. In addition to aromatic hydrocarbon groups having 6 to 20 carbon atoms (aryl groups, etc.) such as unsaturated aliphatic hydrocarbon groups (alkenyl groups, etc.), phenyl groups, naphthyl groups, etc. A group in which one or more hydrogen atoms in a group, an unsaturated aliphatic hydrocarbon group or an aromatic hydrocarbon group is substituted with at least one group selected from a hydroxy group, a carboxyl group, an ether group and an ester group, and the like. Can be mentioned.

In the lactone ring structure, for example, a (meth) acrylic acid-based monomer A having a hydroxy group and a (meth) acrylic acid-based monomer B are polymerized (preferably copolymerized) to form a molecular chain with a hydroxy group and an ester group or carboxyl. After introducing the groups, it can be formed by causing dealcoholization or dehydration cyclization condensation between these hydroxy groups and ester groups or carboxyl groups. As the polymerization component, the (meth) acrylic acid-based monomer A having a hydroxy group is indispensable, and the (meth) acrylic acid-based monomer B includes the monomer A. Monomer B may or may not match monomer A. When the monomer B matches the monomer A, the monomer A is homopolymerized. Note that "(meth) acrylic acid" is a general term for acrylic acid and methacrylic acid, and "(meth) acrylic acid" such as "(meth) acrylic acid-based monomer" and "(meth) acrylic acid ester" is used. The same applies when "acid" is combined with another name.

Examples of the (meth) acrylate-based monomer A having a hydroxy group include 2- (hydroxymethyl) acrylate, 2- (hydroxyethyl) acrylate, and alkyl 2- (hydroxymethyl) acrylate (for example, 2- (hydroxymethyl). ) Methyl acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t-butyl 2- (hydroxymethyl) acrylate), Alkyl 2- (hydroxyethyl) acrylate (for example, methyl 2- (hydroxyethyl) acrylate, ethyl 2- (hydroxyethyl) acrylate) and the like can be mentioned, with preference given to 2- (hydroxyaryl) monomer having a hydroxyallyl moiety. Examples thereof include (hydroxymethyl) acrylate and alkyl 2- (hydroxymethyl) acrylate. Particularly preferably, methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate can be exemplified.

As the (meth) acrylic acid-based monomer B, a monomer having a vinyl group and an ester group or a carboxyl group is preferable, and for example, (meth) acrylic acid, alkyl (meth) acrylic acid (for example, methyl (meth) acrylic acid, etc., Ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, etc., preferably methyl methacrylate), (meth) Aryl acrylate (eg, phenyl (meth) acrylate, benzyl (meth) acrylate, etc.), Alkyl 2- (hydroxyalkyl) acrylate (eg, methyl 2- (hydroxymethyl) acrylate, 2- (hydroxymethyl)) Alkyl 2- (hydroxymethyl) acrylate, such as ethyl acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t-butyl 2- (hydroxymethyl) acrylate, 2 -(Hydroxyethyl) methyl acrylate and the like 2- (hydroxyethyl) alkyl acrylate and the like) and the like.

The glutaric anhydride structure or the glutarimide structure is, for example, a structure represented by the following general formula (2) (in the following general formula (2), when X ¹ is an oxygen atom, it becomes a glutaric anhydride structure. When X ¹ is a nitrogen atom, it has a glutarimide structure).

^{R 4} and R ⁵ in the above general formula (2) are independent of each other as a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ⁶ does not exist, and when X ¹ is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group). , Butyl group, pentyl group, hexyl group), cyclopentyl group, cyclohexyl group or phenyl group.

^{The glutaric anhydride structure in which X 1} is an oxygen atom in the above general formula (2) is, for example, dealcoholization-condensation of a copolymer of (meth) acrylic acid ester and (meth) acrylic acid in the molecule. Can be formed by ^{The glutarimide structure in which X 1} in the general formula (2) is a nitrogen atom can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.

The maleic anhydride structure or the N-substituted maleimide structure is, for example, a structure represented by the following general formula (3) (in the following general formula (3), when X ² is an oxygen atom, the maleic anhydride structure is used. When X ² is a nitrogen atom, it has an N-substituted maleimide structure).

^{R 7} and R ⁸ in the above general formula (3) are independent of each other as a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁹ does not exist, and when X ² is a nitrogen atom, R ⁹ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group). , Butyl group, pentyl group, hexyl group), cyclopentyl group, cyclohexyl group, benzyl group or phenyl group.

^{The maleic anhydride structure in which X 2} in the general formula (3) is an oxygen atom can be formed, for example, by subjecting maleic anhydride to polymerization. ^{The N-substituted maleimide structure in which X 2} in the general formula (3) is a nitrogen atom can be formed, for example, by subjecting an N-substituted maleimide such as phenylmaleimide to polymerization.

As the unit having a ring structure (preferably a unit having a ring structure in the main chain), one kind or two or more kinds can be appropriately combined. Preferably, only one unit having a ring structure (preferably a unit having a ring structure in the main chain) is introduced into the polymer block (B) without combining two or more types.

The polymer block (A) may have one or more types, and the polymer block (B) may also have one or more types. Further, the block copolymer (C) may contain a polymer block (X) different from these polymer blocks (A) and (B), and the polymer block (X) is also one or two kinds. It may be the above. The monomer unit constituting the polymer block (X) can be appropriately selected from the monomer units that can be used for the polymer block (A) and (B).

The amount (soft segment amount) of the polymer block (A) is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, based on 100 parts by mass of the total of the polymer block (A) and the polymer block (B). It is preferably 27 parts by mass or more, for example, 90 parts by mass or less, preferably 70 parts by mass or less, and more preferably 60 parts by mass or less. The total of the polymer block (A) and the polymer block (B) is, for example, 70 parts by mass or more, preferably 80 parts by mass or more, and more preferably 90 parts by mass in 100 parts by mass of the block copolymer (C). With the above, 100 parts by mass may be used.
The amount of the soft segment can be calculated based on the integrated value of ^{1 1 H-NMR.}

Further, the content of the soft segment (A) is 5 parts by mass or more and 90 parts by mass or less (preferably 10 parts by mass or more, more preferably 27 parts by mass or more) in 100 parts by mass of the block copolymer (C). It is preferably 70 parts by mass or less, more preferably 60 parts by mass or less), and the tensile elastic modulus of the block copolymer (C) is preferably 0.5 GPa or more and 2.0 GPa or less. In this case, the tensile elastic modulus of the block copolymer (C) is preferably 1.0 GPa or more, preferably 1.5 GPa or less. By increasing the tensile elastic modulus of the block copolymer (C) while increasing the amount of the polymer block (A) (the amount of soft segments) in the block copolymer (C), the strength of the stretched film tends to increase.
The tensile elastic modulus of the block copolymer (C) is such that the block copolymer is made into an unstretched film of 160 ± 10 μm by melt press molding, the test piece size is 80 mm × 20 mm, and the initial chuck distance is 40 mm. Can be measured in accordance with the provisions of JIS K7161 and JIS K7127.

When the block copolymer (C) is composed of a polymer block (A) (soft segment A) and a polymer block (B) (hard segment B), the block structures are AB type and BA. -B type, ABA type, ABBA type, ABBABA type, BABBAB type and the like can be appropriately adopted, preferably A. -B type and B-AB type.

The method for producing the block copolymer (C) is not particularly limited, and a method according to a known method can be adopted.
For example, a method of living polymerization of a monomer which is a constituent unit of each block (for example, the method described in "Polymer Synthesis Developed by Precision Polymerization" (edited by The Chemical Society of Japan, Kagaku-Dojin Publishing, Paragraphs 14-39, 2016)). Is commonly used. As such a living polymerization method, for example, a method of anionic polymerization using an organoalkali metal compound as a polymerization initiator in the presence of an organoaluminum compound, which is a method described in JP-A-11-335432, JP-A-6- A method for polymerizing an organoraluminal metal complex as a polymerization initiator, which is a method described in Japanese Patent Application Laid-Open No. 93060. Chem. Phys. A method of radical polymerization in the presence of a copper compound using an α-halogenated ester compound as an initiator, which is the method described in Vol. 201, pp. 1108 to 1114 (2000), described in Macromolecules, Vol. 26, pp. 2987 (1993). Nitroxyl group-mediated polymerization, a method according to Macromolecules, Vol. 28, p. 2093 (1995), Atom Transfer Radical Polymerization, a method according to Macromolecules, Vol. 31, p. 5559 (1998). Chain transfer polymerization and the like can be mentioned.

(1.2) Matrix resin (D)
The stretched film of the present invention may contain the block copolymer (C) itself as a resin component, or may contain a matrix resin (D) other than the block copolymer (C) as a resin component. The matrix resin (D) may be a homopolymer or a random copolymer, or may be a polymer alloy composed of two or more of the homopolymer and the random copolymer. When the matrix resin (D) is contained, the amount of the block copolymer (C) is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 15 parts by mass with respect to 100 parts by mass of the matrix resin (D). It is 5 parts by mass or more, for example, 70 parts by mass or less, preferably 60 parts by mass or less, and more preferably 50 parts by mass or less.
The amount of the soft segment (A) of the block copolymer (C) is, for example, 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, for example, in 100 parts by mass of the stretched film. , 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less. Within the above range, a block copolymer (C) that is excellent in melt moldability when mixed with a matrix resin described later and that gives sufficient transparency, tear strength, and flexibility when made into a stretched film can be obtained. Can be provided.

As the matrix resin (D), a (meth) acrylic resin (D1) is preferable. The (meth) acrylic resin (D1) preferably has a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as essential constituent units, and is derived from a derivative of (meth) acrylic acid. It may have a unit.

The (meth) acrylic acid ester (unit) may be either a (meth) acrylic acid ester (unit) or a (meth) acrylic acid ester derivative (unit), for example, methyl (meth) acrylic acid, (. Ethyl acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) Esters of (meth) acrylic acid and hydroxycarbohydrates such as 2-ethylhexyl acrylate, benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate (alkyl (meth) acrylate, (meth)) Ether bond-introduced derivatives such as aryl acrylate, aralkyl (meth) acrylate), dicyclopentanyloxyethyl (meth) acrylate; halogens such as chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate. Introduced derivatives; and hydroxy group-introduced derivatives. The hydroxy group-introduced derivatives include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, and (meth). Hydroxyalkyl (meth) acrylates such as 2,3,4,5-tetrahydroxypentyl acrylate; alkyl 2- (hydroxymethyl) acrylate (eg, methyl 2- (hydroxymethyl) acrylate, 2- (hydroxy) Ethyl methyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t-butyl 2- (hydroxymethyl) acrylate, etc.), 2- (hydroxyethyl) acrylate Includes alkyl 2- (hydroxyalkyl) acrylates of alkyl (eg, methyl 2- (hydroxyethyl) acrylate).

The (meth) acrylic acid (unit) may be any of (meth) acrylic acid (unit) and (meth) acrylic acid derivative (unit), and for example, (meth) acrylic such as acrylic acid and methacrylic acid. Acids: Alkylated (meth) acrylic acids such as crotonic acid; hydroxyalkylated (meth) acrylic acids such as 2- (hydroxymethyl) acrylic acid and 2- (hydroxyethyl) acrylic acid. Among these, methyl methacrylate is particularly preferable from the viewpoint of heat resistance and transparency of the film.
The (meth) acrylic acid ester (unit), the (meth) acrylic acid (unit) and their derivatives (units) may each have only one type or two or more types.

The (meth) acrylic resin (D1) contains the above-mentioned (meth) acrylic acid ester, (meth) acrylic acid, and one or more monomers selected from these derivatives in order to improve compatibility and optical properties. It may have other building blocks introduced by copolymerizing with the monomer. Examples of such other monomers include styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, metallic alcohol, allyl alcohol, ethylene, propylene, and the like. Examples thereof include monomers having a polymerizable double bond such as 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methylvinyl ketone, N-vinylpyrrolidone, and N-vinylcarbazole. These other monomers (constituent units) may have only one kind or two or more kinds.

The (meth) acrylic resin (D1) preferably has a ring structure, and more preferably has a ring structure in the main chain. Examples of the ring structure include a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, a maleic anhydride structure, and an N-substituted maleimide structure. Preferred examples, specific examples, and methods for introducing them are the same as those described in the polymer block (B).

When the (meth) acrylic resin (D1) has a lactone ring structure (preferably when the main chain has a lactone ring structure), the content of the lactone ring structure in the resin (D1) is not particularly limited. For example, it is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, further preferably 10 to 70% by mass, and particularly preferably 15 to 60% by mass.

When the (meth) acrylic resin (D1) has a glutaric anhydride structure or a glutarimide structure (preferably when the main chain has a glutaric anhydride structure or a glutarimide structure), the glutaric anhydride structure in the resin (D1). Alternatively, the content of the glutarimide structure is not particularly limited, but is preferably, for example, 5 to 90% by mass, more preferably 10 to 70% by mass, still more preferably 10 to 60% by mass, and particularly preferably 20 to 90% by mass. It is 50% by mass.

When the (meth) acrylic resin (D1) has a maleic anhydride structure or an N-substituted maleimide structure (preferably, the main chain has a maleic anhydride structure or an N-substituted maleimide structure), the resin (D1) has a structure. The content of the maleic anhydride structure or the N-substituted maleimide structure is not particularly limited, but is preferably, for example, 5 to 90% by mass, more preferably 10 to 70% by mass, and further preferably 10 to 60% by mass. , Particularly preferably 15 to 50% by mass.

As the matrix resin (D), it is also possible to contain a resin other than the (meth) acrylic resin (D1) described above. Resins other than the resin (D1) are classified into a polymer having a positive intrinsic birefringence (D2) and a polymer having a negative intrinsic birefringence (D3). The positive and negative of the intrinsic birefringence of the polymer is the direction in which the molecular chain of the polymer is oriented in a layer (for example, a film) in which the molecular chain of the polymer is uniaxially oriented among the light vertically incident on the main surface of the layer (for example, the film). It can be determined based on the value (n1-n2) obtained by subtracting the refractive index n2 of the layer for the vibration component perpendicular to the orientation axis from the refractive index n1 of the layer for the vibration component parallel to the alignment axis). The positive or negative of the intrinsic birefringence of a polymer is determined by the balance of birefringence caused by each structural unit contained in the polymer. A structural unit having an action of giving a positive (or negative) intrinsic birefringence to a polymer is a structural unit in which the intrinsic birefringence of the formed homopolymer becomes positive (or negative) when a homopolymer of the unit is formed. To say. The polymer having a ring structure described above (preferably a polymer having a ring structure in the main chain) typically exhibits positive intrinsic birefringence.

Examples of the polymer (D2) exhibiting positive intrinsic birefringence include cycloolefin polymers and cellulose derivatives.

A polymer (D3) exhibiting negative intrinsic birefringence typically includes a polymer having a structural unit with a ring structure in the side chain. For example, an α, β-unsaturated monomer having an aromatic group (phenyl group, benzyl group, trill group, xsilyl group, etc.) or a heteroaromatic group (eg, carbazole group, pyridine group, imidazole group, thiophene group, etc.) Examples include polymers having structural units that contribute to negative intrinsic polyrefractive properties, such as units, N-vinyllactam units. Specifically, examples of the α, β-unsaturated monomer unit having an aromatic group include a styrene unit, and specific polymers include a styrene-acrylonitrile copolymer and a styrene-N-phenylmaleimide. Examples include polymers and styrene-acrylonitrile-N-phenylmaleimide copolymers. Examples of the α, β-unsaturated monomer unit having a heteroaromatic group include N-vinylcarbazole unit, vinylpyridine unit, vinylimidazole unit and vinylthiophene unit, and examples of the N-vinyllactam unit include. , N-Vinyl-2-pyrrolidone unit, N-vinyl-ε-caprolactam unit, N-vinyl-2-piperidone unit, N-vinyl-4-methyl-2-pyrrolidone unit, N-vinyl-5-methyl-2 -Pyrrolidone unit, N-vinyl-ω-heptalactam unit can be mentioned. These structural units may be only one type or two or more types.

The polymer exhibiting negative intrinsic birefringence may have other structural units in addition to the structural units that contribute to the negative intrinsic birefringence described above, as long as the negative birefringence is not impaired. .. Other structural units include acrylic acid, methacrylic acid, acrylic acid alkyl esters (eg methyl acrylate, ethyl acrylate, carbazoyl ethyl acrylate), methacrylic acid alkyl esters (eg methyl methacrylate, ethyl methacrylate, carbazoyl ethyl methacrylate), acrylics. Acid aminoalkyl esters (eg diethylaminoethyl acrylate), methacrylic acid aminoalkyl esters, monoesters of acrylic acid and glycol, monoesters of methacrylic acid and glycol (eg hydroxyethyl methacrylate), alkali metal salts of acrylic acid, methacrylic acid Alkali metal salt, ammonium salt of acrylic acid, ammonium salt of methacrylic acid, quaternary ammonium derivative of acrylic acid aminoalkyl ester, quaternary ammonium derivative of methacrylic acid aminoalkyl ester, diethylaminoethyl acrylate and methylsulfate. Quadruple ammonium compound, vinyl methyl ether, vinyl ethyl ether, alkali metal salt of vinyl sulfonic acid, ammonium salt of vinyl sulfonic acid, allyl sulfonic acid, allyl sulfonate, metharyl sulfonic acid, metharyl sulfonate, vinyl acetate , Vinyl stearate, N-vinylacetamide, N-vinylformamide, acrylamide, methacrylicamide, N-alkylacrylamide, N-methylolacrylamide, N, N-methylenebisacrylamide, glycol diacrylate, glycol dimethacrylate, glycol diallyl ether, Examples thereof include structural units formed by polymerization of monomers such as acrylonitrile.

(1.3) Additives The stretched film of the present invention may further contain additives, if necessary. Examples of the additive include an antioxidant; a light-resistant stabilizer, a weather-resistant stabilizer, a stabilizer such as a heat stabilizer; a reinforcing material such as a glass fiber and a carbon fiber; an ultraviolet absorber; a near-infrared absorber; a tris (dibromopropyl). ) Flame retardants such as phosphate, triallyl phosphate, antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers; Resin modifiers; organic fillers and inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants; and the like.

The antioxidant is not particularly limited, but for example, known antioxidants such as phenol-based, phosphorus-based, and sulfur-based can be used alone or in combination of two or more.
Examples of the phenolic antioxidant include n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and n-octadecyl-3- (3,5-di-t-butyl). -4-Hydroxyphenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl -3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di-) t-Butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-) Butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n-octylthio) ethyl-3,5-di-t-butyl- 4-Hydroxybenzoate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenylacetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl- 4-Hydroxyphenylacetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxyethylthio) ethyl-3,5-di-t- Butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl-3- (3,5-di-t) -Butyl-4-hydroxyphenyl) propionate, stearylamide-N, N-bis- [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N -Bis- [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl-3,5-di-t-butyl-4 -Hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycolbis- [3- (3) , 5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenylacetate), glycerin-1-n-octadeca Noate-2,3-bis- (3,5-di-t-butyl-4-hydroxyphenylacetate), pentaerythritol tetrakis- [3- (3', 5'-di-t-butyl-4'-) Hydroxyphenyl) propionate], 1,1,1-trimethylol ethanetris- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], sorbitol hexa- [3- (3,5-) Di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) propionate, 2-stearoyloxyethyl-7- (3-) Methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediolbis [(3', 5'-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis ( 3,5-di-t-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene , 3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] -2,4,8,10-tetraoxa Spiro [5,5] -Undecane, 2,4-di-t-Amil-6- [1- (3,5-di-t-Amil-2-hydroxyphenyl-2-hydroxy-5-methylbenzyl)- Examples thereof include 4-methylphenyl acrylate.

Examples of sulfur-based antioxidants (particularly thioether-based antioxidants) include pentaerythrityl tetrakis (3-laurylthiopropionate), dilauryl-3,3'-thiodipropionate, and dimyristyl-3,3'. -Thiodipropionate, distearyl-3,3'-thiodipropionate and the like can be mentioned.

Examples of the phosphorus-based antioxidant (phosphate-based antioxidant) include tris (2,4-di-t-butylphenyl) phosphite and 2-[[2,4,8,10-tetrakis (1,)). 1-Dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosfepine-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis] (1,1-Dimethylethyl) Dibenzo [d, f] [1,3,2] dioxaphosfepine-6-yl] oxy] -ethyl] etanamine, diphenyltridecylphosphite, triphenylphosphite, 2 , 2-Methylenebis (4,6-di-t-butylphenyl) octylphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaeristol diphosphite, distearylpentaerythritol diphos Examples thereof include phyto, cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite and the like.

Examples of the ultraviolet absorber include benzophenone compounds, salicylate compounds, benzoate compounds, triazole compounds, triazine compounds and the like. Examples of the benzophenone compound include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2-hydroxy-4-n-. Examples thereof include octyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, and 1,4-bis (4-benzoyl-3-hydroxyphenone) -butane.

Examples of the silicate-based compound include pt-butylphenyl silicate and the like.
Examples of the benzoate compound include 2,4-di-t-butylphenyl-3', 5'-di-t-butyl-4'-hydroxybenzoate and the like.
Examples of the triazole-based compound include 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2-. (3,5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazole-2-yl) -p-cresol, 2- (2H-benzotriazole-2-) Il) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazole-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzo Triazole-2-yl] -4-methyl-6-t-butylphenol, 2- (2H-benzotriazole-2-yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazole-2-) Il) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazole-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthal) Imidylmethyl) phenol, methyl 3- (3- (2H-benzotriazole-2-yl) -5-t-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product, 2- (2H-benzo Triazole-2-yl) -6- (straight and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (Α, α-Dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazole-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and Examples include linear alkyl esters.

Further, examples of the triazine-based compound include 2-mono (hydroxyphenyl) -1,3,5-triazine compound and 2,4-bis (hydroxyphenyl) -1,3,5-triazine compound, 2,4. Examples include 6-tris (hydroxyphenyl) -1,3,5-triazine compounds, specifically 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5- Triazine, 2,4-diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3, 5-triazine, 2,4-diphenyl- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1, 3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyl) Oxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2) -Hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-Hydrazine-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, 2,4,6-tris (2-hydroxy-4-methoxyphenyl) -1 , 3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-ethoxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-butoxyphenyl) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy- 4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4,6 -Tris (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1,3,5-triazine, 2 , 4,6-Tris (2-Hydroxy-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-Hydroxy-4-propoxyethoxyphenyl) -1,3,5 -Triazine, 2,4,6-tris (2-hydroxy-4-methoxycarbonylpropyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxycarbonylethyloxy) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1, 3,5-Triazine, 2,4,6-Tris (2-Hydroxy-3-methyl-4-methoxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-Hydroxy-3-3) Methyl-4-ethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-propoxyphenyl) -1,3,5-triazine, 2,4 6-Tris (2-Hydroxy-3-methyl-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-Hydroxy-3-methyl-4-butoxyphenyl) -1, 3,5-Triazine, 2,4,6-Tris (2-Hydroxy-3-methyl-4-hexyloxyphenyl) -1,3,5-Triazine, 2,4,6-Tris (2-Hydroxy-3) -Methyl-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-dodecyloxyphenyl) -1,3,5-triazine, 2 , 4,6-Tris (2-Hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-Tris (2-Hydroxy-3-methyl-4-ethoxyethoxy) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) 2-Hydroxy-3-methyl-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxycarbonylpro) Pyroxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl) -1,3,5-triazine, 2,4 6-Tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine and the like can be mentioned.

Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4. An ultraviolet absorber having a-(3-alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (alkyloxy; long-chain alkyloxy groups such as octyloxy, nonyloxy, and decyloxy) can be mentioned. Be done.

Further, an ultraviolet absorber having a 2,4,6-tris (hydroxyphenyl) -1,3,5-triazine skeleton is preferably used, and 2,4,6-tris (2-hydroxy-4-long chain alkyloxy) is preferably used. Group-substituted phenyl) -1,3,5-triazine skeleton and 2,4,6-tris (2-hydroxy-3-alkyl-4-long-chain alkyloxy group-substituted phenyl) -1,3,5-triazine skeleton The UV absorber to have is a triazine-based UV absorber which is particularly preferable. Examples of commercially available products include "Tinubin (registered trademark) 1577", "Tinubin (registered trademark) 460", "Tinubin (registered trademark) 477" (manufactured by BASF Japan), and "Adeka Tabun (registered trademark)" as triazine-based ultraviolet absorbers. ) LA-F70 ”(manufactured by ADEKA), examples of the triazole-based ultraviolet absorber include“ ADEKA STABUN (registered trademark) LA-31 ”(manufactured by ADEKA). These can be used alone or in combination of two or more.

The content ratio of the additive in the stretched film is preferably 0 to 5% by mass, more preferably 0 to 2% by mass.

(1.4) Stretched film The stretched film of the present invention contains the above-mentioned components, and has high flexibility, retains tear strength, and has a low haze value.

The stretched film of the present invention has a folding resistance improvement index measured by the following method, preferably 1.1 or more, more preferably 1.5 or more, still more preferably 2 or more, for example, 10 or less, and further. It may be 5 or less.
[Measurement method of folding resistance improvement index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film were molded into a length of 90 mm, a width of 15 mm, and a thickness of 40 μm, respectively, at 23 ° C. The film is allowed to stand at 50% RH for 1 hour or more, and is reciprocally bent under the conditions of a bending angle of 135 °, a bending speed of 175 cpm, and a load of 200 g, and the number of reciprocating bends until the film is broken is measured by 5 sheets each. Folding number M ₁ the average value of the reciprocating folding number was measured for the stretched film, the average value of the reciprocating folding number was measured for the stretched film of the matrix resin as a folding number M _0, their ratio (M ₁ / M ₀ ) Is used as the folding resistance improvement index.

Further, the stretched film of the present invention has a tear strength retention index measured by the following method, preferably 0.50 or more, more preferably 0.76 or more, still more preferably 0.8 or more, for example, 2 or less. It may be more preferably 1.5 or less, still more preferably 1.2 or less.
[Measurement method of tear strength retention index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film are molded into a length of 120 mm, a width of 30 mm, and a thickness of 40 μm, respectively, at 200 mm / min. Perform the test at the test speed of and measure the tear strength. A tear strength Tr ₁ measured for stretched film, a ratio (Tr ₁ / Tr ₀₎ tear strength retention index and tear strength Tr ₀ measured for the stretched film of the matrix resin.

The haze of the stretched film of the present invention is preferably 0.5% or less, more preferably 0.3% or less, still more preferably 0.2% or less, for example, 0.01% or more, more preferably 0.02. % Or more, more preferably 0.03% or more.

The thickness of the stretched film cannot be unconditionally determined because it varies depending on the application, but it is preferably 1 μm or more and 400 μm or less, for example. In particular, when the stretched film is used for applications such as a protective film, an antireflection film, and a polarizing film used in an image display device, the thickness of the stretched film is preferably 1 μm or more, more preferably 10 μm or more, and more preferably 20 μm. The above is more preferable, 250 μm or less is preferable, 100 μm or less is more preferable, and 80 μm or less is further preferable. When the stretched film is used for a transparent conductive film, the thickness of the stretched film is preferably 20 μm or more, more preferably 30 μm or more, further preferably 40 μm or more, still preferably 400 μm or less, and preferably 350 μm or less. Is more preferable, and 300 μm or less is further preferable. The thickness of the stretched film is measured using, for example, a digital micrometer (manufactured by Mitutoyo Co., Ltd.).

The stretched film includes, for example, a protective film for an optical disk, a polarizing element protective film used for a polarizing plate of an image display device such as a liquid crystal display device, a retardation film, a viewing angle compensation film, a light diffusing film, a reflective film, and an antireflection film. It can be used for optical applications such as antiglare films, brightness improving films, conductive films for touch panels, diffusers, light guides, and prism sheets. Therefore, the stretched film is expected to be suitably used for applications such as liquid crystal display devices, image display devices such as organic EL display devices, and capacitive touch panels.

When the stretched film is applied to the polarizer protective film, the stretched film (polarizer protective film) may be provided on one side or both sides of the polarizer to form a polarizing plate. The type of the polarizer is not particularly limited, and for example, a polarizer obtained by dyeing and stretching a polyvinyl alcohol film; a polyene polarizer such as a dehydrated polyvinyl alcohol or a dehydroxylated polyvinyl chloride; a multilayer laminate or cholesteric. Reflective polarizer using a liquid crystal; a polarizer made of a thin film crystal film and the like can be mentioned. As an example of the structure of the polarizing plate, polyvinyl alcohol is dyed with a dichroic substance such as iodine or a dichroic dye, and then uniaxially stretched to obtain a polarizing element, and a polarizing element protective film is formed on one or both sides of the polarizing element. Examples thereof include a structure in which (stretched films) are bonded.

Since the stretched film of the present invention has excellent optical properties and excellent flexibility, it can be applied to a wide range of applications. Above all, it can be suitably used for optics, and in particular, it can be suitably used as a raw material for an optical film or the like.

The stretched film of the present invention prepares a resin composition containing a block copolymer (C), a matrix resin (D) used as necessary, and an additive, melt-molds the resin composition, and further stretches the resin composition. Can be formed by

Examples of the method for melt-molding the resin composition include a melt extrusion molding method such as a T-die method and an inflation method, a cast molding method, a press molding method, and the like. A shaft extruder, a twin-screw extruder, or the like can be used.

The stretched film of the present invention may be either a uniaxially stretched film or a biaxially stretched film, but a biaxially stretched film is particularly preferable. In the case of biaxial stretching, since the film is stretched in two orthogonal directions, the mechanical fracture strength in an arbitrary direction in the film plane is improved, and the film performance is improved. Further, the in-plane phase difference of the film is reduced, and it becomes easy to obtain a stretched film having high optical isotropic properties. When it is a biaxially stretched film, it may be either a simultaneous biaxially stretched film or a sequential biaxially stretched film.

The draw ratio of the stretched film is preferably about 1.5 times to 3.0 times, and 1.5 times to 2. times, respectively, in both the vertical direction and the horizontal direction orthogonal to the vertical direction. More preferably, it is about 8 times.

An optical film having a transparent conductive layer formed on the surface of the stretched film can be used as the transparent conductive film. Examples of the transparent conductive layer include an inorganic compound layer having a property of reflecting infrared rays such as an indium-tin oxide (ITO) layer, and a metal mesh layer made of a metal such as silver, copper, nickel and tungsten. ..

The stretched film may be provided with a coating layer on at least one surface, if necessary. Examples of the coating layer include an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, an antiglare (non-glare) layer, a photocatalyst layer, an antifouling layer, an antireflection layer, a hard coat layer, an ultraviolet shielding layer, and a heat ray. Examples thereof include a shielding layer, an electromagnetic wave shielding layer, and a gas barrier layer. Further, an optical adjustment layer for appropriately adjusting the transmittance or reflectance of the incident light rays may be provided on the surface of the stretched film.

Examples of the image display device provided with the stretched film include a liquid crystal display device. The liquid crystal display device can be configured such that the image display unit has the stretched film of the present invention together with members such as a liquid crystal cell, a polarizing plate, and a backlight. In this case, the image display device includes, for example, a stretched film as a polarizer protective film constituting a polarizing plate.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples as well as the present invention, and appropriate modifications are made to the extent that it can be adapted to the gist of the above and the following. Of course, it is possible to carry out, and all of them are included in the technical scope of the present invention. In the following, unless otherwise specified, "part" means "part by mass" and "%" means "% by mass".

The measurement and evaluation of various physical properties in the following examples were carried out by the following methods.
<Weight average molecular weight>
The weight average molecular weight Mw of the block polymer and the polymer was determined by polystyrene conversion using gel permeation chromatography (GPC). The equipment and measurement conditions used for the measurement are as follows.
System: GPC system HLC-8220 manufactured by Tosoh Corporation
Measurement side column configuration ・ Guard column: manufactured by Tosoh Corporation, TSKguardcolum SuperHZ-L
-Separation column: Tosoh Corporation, TSKgel SuperHZM-M 2 series connection Reference side column configuration-Reference column: Tosoh Corporation, TSKgel SuperH-RC
Developing solvent: Chloroform (manufactured by Wako Pure Chemical Industries, Ltd., special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (manufactured by Tosoh Corporation, PS-oligomer kit)
Column temperature: 40 ° C

<Calculation of monomer conversion rate>
The conversion rate was determined by measuring the amount of residual monomer using gas chromatography (manufactured by Shimadzu Corporation, device name: GC-2014).

<Glass transition temperature>
The glass transition temperature (Tg) of the block copolymer was determined by the starting point method in accordance with the provisions of JIS K7121. Specifically, for Tg observed at 40 ° C. or higher, a differential scanning calorimeter (DSC-8230, manufactured by Rigaku Co., Ltd.) was used, and a sample of about 10 mg was sampled at 25 ° C. to 10 ° C. per minute under a nitrogen gas atmosphere. It was obtained from a DSC curve stabilized by repeating the temperature rise to 200 ° C. at a heating rate a plurality of times. In addition, α-alumina was used as a reference.
For Tg observed at less than 40 ° C, a differential scanning calorimeter (NETZSCH, DSC3500A) was used, and a sample of about 10 mg was sampled at a heating rate of -100 ° C to 20 ° C per minute under a nitrogen gas atmosphere. It was obtained from a DSC curve stabilized by repeating the temperature rise to ° C. a plurality of times.

<Amount of soft segment>
The repeating unit derived from the methacrylate monomer and the repeating unit derived from the acrylate monomer were identified from ¹ H-NMR and ¹³ C-NMR, and the abundance of each unit was calculated from the integrated value in ^{1 H-NMR.} ..
Measuring equipment: Unity Plus400 manufactured by Varian, or AVANCE III manufactured by BRUKER
Measuring solvent: CDCl ₃ , or d-acetone

<Production of film>
The block copolymer or resin composition was melt-press molded using a manual heating press (manufactured by Imoto Seisakusho, IMC-180C type) to prepare an unstretched film of 160 ± 10 μm.

<Film thickness>
The thickness of the film was measured using a digital micrometer (manufactured by Mitutoyo Co., Ltd.). Samples for measuring and evaluating the physical properties of the film, including the physical properties showing the evaluation method below, were obtained from the central portion in the width direction of the film.

<Tensile modulus of film>
The tensile elastic modulus was determined by performing a tensile test in accordance with the provisions of JIS K7161 and JIS K7127, except that the test piece size was 80 mm × 20 mm and the initial chuck distance was 40 mm. Specifically, the film cut out to the size of the test piece is controlled by temperature and humidity in a constant temperature and humidity chamber (23 ° C., 60% RH setting) for 12 hours or more, and then an autograph (AGS-X, manufactured by Shimadzu Corporation) is used. Then, a tensile test was performed at a speed of 23 ° C. and 10 mm / min, and the stress corresponding to the obtained strain of 0.01% to 2% was defined as the y-axis and the strain was defined as the x-axis. The inclination was obtained, and the value was taken as the tensile elastic modulus [GPa].

<Film haze>
The haze of the film was measured by filling a quartz cell with 1,2,3,4-tetrahydronaphthalene (tetralin) using NDH-1001DP manufactured by Nippon Denshoku Kogyo Co., Ltd. and immersing the film in it. It was calculated as.

<Folding resistance (MIT)>
The number of times the film was folded was measured according to JIS P8115. Specifically, two types of test films having a length of 90 mm and a width of 15 mm are allowed to stand at 23 ° C. and 50% RH for 1 hour or more before use, and a MIT fracture resistance tester (manufactured by Toyo Seiki Co., Ltd., DA) is used. The test was carried out under the conditions of a bending angle of 135 °, a bending speed of 175 cpm, and a load of 200 g, and the average value of the number of times until the films of the five samples were broken was obtained.

<Truser tear strength>
The trouser tear strength of the film was determined in accordance with JIS K7128-1. Specifically, a test film having a length of 120 mm and a width of 30 mm is allowed to stand at 23 ° C. and 50% RH for 1 hour or more before use, and an autograph (manufactured by Shimadzu Corporation, AGS-X) is used. The test was carried out at a test speed of 200 mm / min, and the average value of 35 mm excluding 20 mm at the start of tearing and 5 mm before the end of tearing was calculated, and the average value of 5 samples was used as the measurement result.

<Synthesis Example 1>: Synthesis of polymer block (A-1) (soft segment) 0.44 parts by mass of 2,5-dibromo in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Diethyl adipate and 95.3 parts by mass of ethyl acrylate (AE) were charged, and the temperature was raised to 80 ° C. while passing nitrogen through the mixture. Then, 0.19 parts by mass of cuprous bromide and 0.23 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 3.8 parts by mass of acetonitrile were added. The reaction was allowed to proceed for 2 hours and 30 minutes. Further, 0.03 parts by mass of cuprous bromide, 0.13 parts by mass of tris [2- (dimethylamino) ethyl] amine, and 1.9 parts by mass of acetonitrile were added, and the reaction was carried out for 1 hour and 30 minutes. Was advanced. The reaction solution was filtered through activated alumina to remove the catalyst residue, and then heated at 80 ° C. under vacuum for about 1 hour or more to remove the residual monomer and solvent to obtain a polymer block (A-1).

<Synthesis Example 2>: Synthesis of polymer block (A-2) (soft segment) 0.59 parts by mass of cuprous bromide was added to a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. , 0.7 parts by mass of diethyl 2,5-dibromoadipate, 19.5 parts by mass of n-butyl acrylate (BA), and 78.1 parts by mass of methyl acrylate (MA) were charged, and nitrogen was passed through the mixture. At the same time, the temperature was raised to 80 ° C. Then, 0.41 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine was added, and the reaction was allowed to proceed for 7 hours. The catalyst residue was removed in the same manner as in Synthesis Example 1, and the monomer and solvent were removed to obtain a polymer block (A-2).

<Synthesis Example 3>: Synthesis of polymer block (A-3) (soft segment) 0.59 parts by mass of cuprous bromide was added to a reaction device equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction tube. , 0.7 parts by mass of diethyl 2,5-dibromoadipate, 48.8 parts by mass of n-butyl acrylate (BA), and 48.8 parts by mass of n-butyl methacrylate (BMA) were charged therein. The temperature was raised to 80 ° C. through nitrogen. Then, 0.41 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine was added, and the reaction was allowed to proceed for 7 hours. The catalyst residue was removed in the same manner as in Synthesis Example 1, and the monomer and solvent were removed to obtain a polymer block (A-3).

<Synthesis Example 4>: Synthesis of polymer block (A-4) (soft segment) 0.19 parts by mass of cuprous bromide in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. , 0.45 parts by mass of diethyl 2,5-dibromoadipate and 95.3 parts by mass of n-butyl acrylate (BA) were charged, and the temperature was raised to 80 ° C. through nitrogen. Then, 0.24 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 3.8 parts by mass of acetonitrile were added, and the reaction was allowed to proceed for 2 hours. Further, 0.15 parts by mass of cuprous bromide, 0.42 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 6.6 parts by mass of acetonitrile were added for 7 hours. The reaction was allowed to proceed. The catalyst residue was removed and the monomer and solvent were removed in the same manner as in Synthesis Example 1 to obtain a polymer block (A-4).

<Synthesis Example 5>: Synthesis of polymer block (A-5) (soft segment) 0.17 parts by mass of 2,5-dibromo in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Diethyl adipate and 95.8 parts by mass of ethyl acrylate (AE) were charged, and the temperature was raised to 80 ° C. while passing nitrogen through the mixture. Then, 0.07 parts by mass of cuprous bromide, 0.10 parts by mass of tris [2- (dimethylamino) ethyl] amine, and 3.8 parts by mass of acetonitrile were added, and the reaction proceeded for 2 hours. I let you. The reaction solution was filtered through activated alumina to remove the catalyst residue, and then heated at an absolute pressure of 2.4 kPa at 80 ° C. for about 1 hour to remove residual monomers and solvent to obtain a polymer block (A-5).

<Synthesis Example 6>: Synthesis of polymer block (A-6) (soft segment) 0.44 parts by mass of 2,5-dibromo in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Diethyl adipate and 105 parts by mass of 2-ethylhexyl acrylate (EHA) were charged, and the temperature was raised to 80 ° C. while passing nitrogen through the mixture. Then, 0.19 parts by mass of cuprous bromide and 0.23 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 3.8 parts by mass of acetonitrile were added. The reaction was allowed to proceed for 2 hours and 30 minutes. Further, 0.03 parts by mass of cuprous bromide, 0.13 parts by mass of tris [2- (dimethylamino) ethyl] amine, and 1.9 parts by mass of acetonitrile were added, and the reaction proceeded for 3 hours. I let you. The reaction solution was filtered through activated alumina to remove the catalyst residue, and then heated at 80 ° C. under vacuum for about 1 hour or more to remove the residual monomer and solvent to obtain a polymer block (A-6).

Table 1 shows the weight average molecular weight Mw, the number average molecular weight Mn, the molecular weight distribution Mw / Mn, and the glass transition temperature of the polymer blocks (A-1) to (A-6) obtained in Synthesis Examples 1 to 6.

<Example 1>: Synthesis of BAB block copolymer (C-1) The polymer synthesized in Synthesis Example 1 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Block (A-1) 15.1 parts by mass, 57.4 parts by mass of methyl methacrylate (MMA), 3.0 parts by mass of methyl acrylate (MA), 12.1 parts by mass of methyl ethyl ketone are charged and passed through nitrogen. The temperature was raised to 80 ° C. Then, 0.18 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine, 0.12 parts by mass of cuprous bromide, and 12.1 parts by mass of methylethylketone as initiators. The mixture was added and the reaction was allowed to proceed for 2 hours, and the catalyst residue was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-1). The block copolymer (C-1) is a B-AB type block in which the polymer blocks (B-1) (hard segments) are bonded to both sides of the polymer blocks (A-1) (soft segments). It is a polymer.

<Example 2>: Synthesis of BAB block copolymer (C-2) The polymer synthesized in Synthesis Example 2 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Block (A-2) 14.2 parts by mass, 67.6 parts by mass of methyl methacrylate (MMA), 3.6 parts by mass of methyl acrylate (MA), 14.2 parts by mass of methyl ethyl ketone are charged and passed through nitrogen. The temperature was raised to 80 ° C. Then, 0.17 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 0.14 parts by mass of cuprous bromide were added as an initiator, and the reaction was carried out for 1.5 hours. The process was carried out, and the catalyst was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-2).

<Example 3>: Synthesis of BAB block copolymer (C-3) The polymer synthesized in Synthesis Example 3 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Block (A-3) 14.2 parts by mass, 67.6 parts by mass of methyl methacrylate (MMA), 3.6 parts by mass of methyl acrylate (MA), 14.2 parts by mass of methyl ethyl ketone are charged and passed through nitrogen. The temperature was raised to 80 ° C. Then, 0.17 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine and 0.14 parts by mass of cuprous bromide were added as an initiator, and the reaction was carried out for 1.5 hours. The process was carried out, and the catalyst was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-3).

<Comparative Example 1>: Synthesis of BAB type block copolymer (C-4) The polymer synthesized in Synthesis Example 4 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Block (A-4) 15.1 parts by mass, 57.4 parts by mass of methyl methacrylate (MMA), 3.0 parts by mass of methyl acrylate (MA), 12.1 parts by mass of methyl ethyl ketone are charged and passed through nitrogen. The temperature was raised to 80 ° C. Then, 0.18 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine, 0.12 parts by mass of cuprous bromide, and 12.1 parts by mass of methylethylketone as initiators. The mixture was added and the reaction was allowed to proceed for 2 hours, and the catalyst residue was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-4).

<Reference Example 1>: Synthesis of BAB type block copolymer (C-5) The polymer synthesized in Synthesis Example 5 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. The temperature was raised to 80 ° C. through 6.0 parts by mass of block (A-5), 86.5 parts by mass of methyl methacrylate (MMA), 4.2 parts by mass of methyl acrylate (MA), and nitrogen. Then, 0.12 parts by mass of tris [2- (dimethylamino) ethyl] amine, 0.07 parts by mass of cuprous bromide, and 3.0 parts by mass of acetonitrile were added as an initiator. The reaction was allowed to proceed for 1 hour, and the catalyst residue was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-5).

<Comparative Example 2>: Synthesis of BAB type block copolymer (C-6) The polymer synthesized in Synthesis Example 6 in a reaction device equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube. Block (A-6) 15.1 parts by mass, 57.4 parts by mass of methyl methacrylate (MMA), 3.0 parts by mass of methyl acrylate (MA), 12.1 parts by mass of methyl ethyl ketone are charged and passed through nitrogen. The temperature was raised to 80 ° C. Then, 0.18 parts by mass of N, N, N', N', N''-pentamethyldiethylenetriamine, 0.12 parts by mass of cuprous bromide, and 12.1 parts by mass of methylethylketone as initiators. The mixture was added and the reaction was allowed to proceed for 2 hours, and the catalyst residue was removed in the same manner as in Synthesis Example 1. The obtained reaction solution was precipitated in a large amount of methanol, filtered, and dried to obtain a block copolymer (C-6).

Regarding the block copolymers (C-1) to (C-6) obtained in Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1, the weight average molecular weight Mw, the number average molecular weight Mn, and the molecular weight distribution (Mw). / Mn), glass transition temperature on the high temperature side (Tg on the high temperature side), glass transition temperature on the low temperature side (Tg on the low temperature side), ^{the ratio of soft segments determined by 1} H-NMR, and the elasticity of the block copolymer. Shown in 2.

<Examples 4 to 7 and Comparative Examples 3 to 8>
Block copolymers (C-1 to C-6) and PMMA (Sumitomo Chemical Co., Ltd .: "Sumipex (registered trademark) EX") obtained in Examples 1 to 3 and Comparative Examples 1 and 2 and Reference Example 1 were used. When the total amount of the mixed resin composition was 100% by mass, the mixture was blended so that the amount of soft segments was as shown in Table 3, the solution was mixed, and the mixture was dried at 240 ° C. and an absolute pressure of 2.4 kPa for 1 hour.
A press film was formed from the obtained resin composition and stretched 2 × 2 times at Tg + 18 ° C. to prepare a stretched film having a thickness of 40 μm, and haze, MIT, and trouser tear strengths were measured, respectively. The results are shown in Table 3.

As shown in Table 3, a stretched film of a resin composition using a block copolymer having a Tg of a soft segment of -30 ° C or higher and 25 ° C or lower and a weight average molecular weight of 20,000 or higher and 400,000 or lower (Example 4). In 7), the folding resistance was improved without a decrease in tear strength with respect to the characteristics of Comparative Example 4, which is a matrix resin containing no block copolymer.
Further, in Comparative Examples 3, 4 and 6 in which the Tg of the soft segment was −40 ° C. or lower, the folding resistance was improved, but the tear strength was lowered, and the haze increased as the amount of the soft segment was increased, which was unsuitable as an optical film. there were. In Comparative Example 8 in which the Tg of the soft segment was −70 ° C., although the folding resistance was improved, the tear strength was lowered and the haze was more likely to increase, which was unsuitable as an optical film. Further, in Comparative Example 7 using a block polymer having a Tg of −17 ° C. and a weight average molecular weight of 490,000, the fracture resistance was improved, but the tear strength was decreased and the haze was increased.

Claims (12)

A stretched film containing a (meth) acrylic acid ester-based block copolymer.
The block copolymer has a polymer block (A) and a polymer block (B).
The glass transition temperature of the block copolymer exists in the range of 80 ° C. or higher and -30 ° C. or higher and 25 ° C. or lower, respectively.
The weight average molecular weight of the block copolymer is state, and are 20,000 400,000 or less,
The polymer block (A) is a polymer block containing a structural unit derived from alkyl methacrylate and / or alkyl acrylate.
In the polymer block (A), the amount of units derived from an alkyl acrylate having an alkyl group having 1 to 3 carbon atoms is 50 parts by mass or more, or alkyl, out of 100 parts by mass of all the units constituting the polymer block (A). The amount of the unit derived from methacrylate is 30 parts by mass or more and 90 parts by mass or less in 100 parts by mass of all the units constituting the polymer block (A).
A stretched film further containing a matrix resin. The stretched film according to claim 1, wherein the polymer block (B) is a polymer block containing a structural unit derived from a methacrylic acid ester. The content of the polymer block (A) containing the structural unit derived from the alkyl methacrylate and / or the alkyl acrylate is 5 parts by mass or more and 90 parts by mass or less in 100 parts by mass of the block copolymer, and the block. The stretched film according to claim 1 or 2, wherein the tensile elastic modulus of the copolymer is 0.5 GPa or more and 2.0 GPa or less. The stretched film according to any one of claims 1 to 3, wherein the polymer block (A) containing a structural unit derived from alkyl methacrylate and / or alkyl acrylate has a weight average molecular weight of 5,000 or more and 200,000 or less. The stretched film according to any one of claims 1 to 4, wherein the polymer block (A) containing the structural units derived from alkyl methacrylate and / or alkyl acrylate contains structural units derived from two or more kinds of monomers. Any of claims 1 to 5, wherein the content of the polymer block (A) containing the structural unit derived from the alkyl methacrylate and / or alkyl acrylate is 1 part by mass or more and 50 parts by mass or less in 100 parts by mass of the stretched film. The stretched film according to. The stretched film according to any one of claims 1 to 6, wherein the content of the block copolymer is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the matrix resin. The stretched film according to any one of claims 1 to 7 , wherein the haze is 0.5% or less. The stretched film according to any one of claims 1 to 8 , wherein the tear strength retention index measured by the following method is 0.50 or more.
[Measurement method of tear strength retention index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film are molded into a length of 120 mm, a width of 30 mm, and a thickness of 40 μm, respectively, at 200 mm / min. Perform the test at the test speed of and measure the tear strength. A tear strength Tr ₁ measured for stretched film, a ratio (Tr ₁ / Tr ₀₎ tear strength retention index and tear strength Tr ₀ measured for the stretched film of the matrix resin. The stretched film according to any one of claims 1 to 9 , wherein the folding resistance improvement index measured by the following method is 1.1 or more.
[Measurement method of folding resistance improvement index]
The matrix film obtained by stretching only the matrix resin contained in the stretched film under the same conditions as the stretched film and the stretched film were molded into a length of 90 mm, a width of 15 mm, and a thickness of 40 μm, respectively, at 23 ° C. The film is allowed to stand at 50% RH for 1 hour or more, and is reciprocally bent under the conditions of a bending angle of 135 °, a bending speed of 175 cpm, and a load of 200 g, and the number of reciprocating bends until the film is broken is measured by 5 sheets each. Folding number M ₁ the average value of the reciprocating folding number was measured for the stretched film, the average value of the reciprocating folding number was measured for the stretched film of the matrix resin as a folding number M _0, their ratio (M ₁ / M ₀ ) Is used as the folding resistance improvement index. The stretched film according to any one of claims 1 to 10 , wherein the thickness is 1 μm or more and 400 μm or less. The stretched film according to any one of claims 1 to 11, wherein the polymer block (B) is a polymer block containing a unit having a ring structure.