WO2013008801A1 - Porous film and reflection plate using same - Google Patents

Abstract

[Problem] To provide: a porous film which has environmental suitability by utilizing a plant-origin compound and exhibits excellent heat resistance and high reflectance of visible light; and a reflection plate which uses the porous film. [Solution] A porous film which contains a specific polymer that contains a skeleton derived from dehydroabietic acid in a repeating unit and which has pores inside.

Description

Porous film and reflector using the same

The present invention relates to a porous film and a reflector using the same.

Some film and sheet materials containing pores exhibit light reflectivity, and because of their heat insulation, cushioning, and light weight, for example, electronic device lighting members, general household lighting members, internal lighting signs, etc. It is used as a reflective material. Particularly in recent years, with the widespread use of liquid crystal televisions and computers, there has been a demand for light reflectors that exhibit higher reflectivity, have heat resistance, and are light in applications for liquid crystal reflectors.
Therefore, as a technique applicable to the reflector, a porous stretched resin that is stretched under atmospheric pressure by contacting the inert gas with the inert gas under pressure when molding the resin film. There is a film (Patent Documents 1 and 2). There is also a reflective film in which voids are formed by mixing and stretching inorganic particles in polyethylene terephthalate (Patent Document 3). Since the porous film made of such a stretched resin film has fine irregularities formed on the surface by the pores, the diffuse reflectance with respect to the total reflectance becomes high when reflecting visible light, Suitable for use.

JP 2006-8942 A JP 2009-244749 JP 2011-25473 A

However, the films described in Patent Documents 1 to 3 use a polymer derived from fossil fuel, and from the viewpoint of recent environmental problems, it is an alternative to one derived from a natural resource with a low equivalent carbon dioxide emission. Is desired. Conventionally, a porous film derived from a natural resource has insufficient heat resistance and could not be used for a reflector. Moreover, it has been desired to obtain a porous film having independent pores formed by a simpler method.
By the way, the present applicant has paid attention to an abietan compound derived from natural resources and succeeded in making it a polymer. And the physical property of the polymer was confirmed, and it discovered that high heat resistance and moisture-and-water resistance could be expressed (Unexamined-Japanese-Patent No. 2011-26569, Unexamined-Japanese-Patent No. 2011-74249). Through subsequent research and development, it was discovered that the polymer can be formed into a porous film having independent pores by a simple method such as a solution casting method. The formation of such independent pores is a phenomenon peculiar to the above polymer, and even if the same method is used, the cellulose ester which is a biomass polymer becomes a through hole.

That is, the present invention aims to provide a porous film that has environmental compatibility by using a plant-derived compound, has excellent heat resistance, and exhibits a high reflectance with respect to visible light, and a reflector using the porous film. To do.

The above problems have been solved by the following means.
[1] A porous membrane comprising a specific polymer containing a skeleton derived from dehydroabietic acid as a repeating unit and having pores therein.
[2] The porous membrane according to [1], wherein the skeleton derived from dehydroabietic acid includes a structure represented by the following formula (U).

(R ^A and R ^B represent an alkyl group or alkenyl group having 1 to 6 carbon atoms. N and m represent an integer of 0 to 3. m represents an integer of 0 to 5. Ring Cy represents a hetero atom. A saturated or unsaturated 6-membered ring or 7-membered ring which may be included is represented, wherein * and ** represent a bond incorporated in the main chain, and * may be a bond extending from ^RA . )
[3] The porous membrane according to [1] or [2], wherein the specific polymer is selected from polymers containing a repeating unit represented by the following formula A1 or A2 in the main chain.

(In the formula, L ¹¹ , L ¹² , L ²¹ , L ²² , and L ²³ represent a divalent linking group. * Represents a bond incorporated in the main chain.)
[4] The porous film according to any one of [1] to [3], wherein in formula A1, the linking group L ¹¹ is bonded to the carbon atom shown at the 2-position in the formula.
[5] The porous membrane according to any one of [1] to [4], wherein in the formula A2, the linking group L ²³ is bonded to the carbon atoms shown at the 2nd and 2 ′ positions in the formula.
[6] L ^{11 in} Formula A1 is * -L ¹³ -CO-** or * -CO-L ¹³ -** (* represents a bond on the hydrophenanthrene ring side. ** is the reverse bond. L ¹³ is an alkylene group, an alkenylene group, an alkynylene group, an arylene group, an oxygen atom, a carbonyl group, or a single bond, and L ¹² is a carbonyl group or a carbonyloxy group [3] ] Or the porous membrane according to [4].
[7] L ²¹ and L ^{22 in} Formula A2 are a carbonyl group or a carbonyloxy group, and L ²³ is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, an alkylene group, an alkenylene group, an arylene group, or a single bond The porous film according to any one of [1] to [6].
[8] The porous film according to any one of [1] to [7], wherein the specific polymer further includes a repeating unit derived from a diol compound having a ring structure.
[9] The hard film according to [8], wherein the copolymer component is represented by the following formula (II).

[G ¹ represents an alkylene group, an alkenylene group, an arylene group, a heteroarylene group, or a linking group obtained by combining these. X, Y and Z are each independently —O—, —S—, —NR—, — (C═O) —, —O (C═O) —, — (C═O) O—, — ( C═O) NR— and a divalent linking group selected from the group consisting of combinations thereof. R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 24 carbon atoms. * Is a bond incorporated in the main chain. mz is an integer of 0 to 3. R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 24 carbon atoms. ]
[10] The porous membrane according to [8], wherein the formula (II) is represented by the following formula (B1).

(L ³ is an oxygen atom, a carbonyl group, a sulfonyl group, an alkylene group, or a single bond. When a plurality of L ³ are present, each of them may be the same or different. R ¹ and R ² are each Independently, it represents a halogen atom, an alkyl group or an alkoxy group and may be bonded to each other to form a ring, and when a plurality of R ¹ and R ² are present, each may be the same or different. n1 and n2 each independently represents an integer of 0 to 4. n3 represents an integer of 0 to 2. * represents a bond.)
[11] The hard film according to any one of [1] to [10], wherein the copolymer component includes a ring structure.
[12] The porous membrane according to any one of [1] to [11], wherein the pores are independent pores having an average pore diameter of 0.5 μm or more and 50 μm or less.
[13] The porous membrane according to any one of [1] to [12], wherein the density of the porous membrane is 0.05 to 0.7 g / cm ³ .
[14] The porous membrane according to any one of [1] to [13], wherein the pores are produced by a solution casting method using phase separation.
[15] A reflector comprising the porous film according to any one of [1] to [14].

The porous film of the present invention and the reflector using the porous film use a plant-derived compound, and have environmental compatibility that greatly contributes to reduction of the equivalent amount of carbon dioxide emission. Furthermore, it has excellent effects of being excellent in heat resistance and reflectance, resistant to heat shrinkage, and being able to easily form a porous film having independent pores by a solution casting method.

It is the perspective view which showed typically the mechanism of the backlight periphery of the liquid crystal device using the reflecting plate as one Embodiment of this invention. It is a drawing substitute photograph which concerns on the electron micrograph which shows the surface of the film produced in the Example. It is a DMA chart for calculating | requiring Tg of the sample prepared in the Example.

The porous membrane of the present invention is made of a specific polymer using a plant-derived compound. This porous membrane has a very high heat resistance despite being derived from a plant, and is resistant to heat shrinkage. This reason includes an unclear point, but is estimated as follows. That is, the specific polymer has a unique matrix created in the resin by two-dimensionally connecting the three-dimensionally chemically stable tricyclic moieties having a skeleton derived from dehydroabietic acid. it is conceivable that. There is no such material, and conventional biomass polymers obtained using biomass resources are usually inferior in heat resistance. Although the specific polymer used in the present invention can use a raw material derived from biomass resources, it exhibits excellent heat resistance as described above. Hereinafter, it demonstrates in detail centering on the preferable embodiment of this invention.

[Specific polymer]
(Repeating unit containing a skeleton derived from dehydroabietic acid)
The specific polymer of the present invention uses dehydroabietic acid represented by the following formula (AA) or a derivative thereof as a raw material monomer. Even a homopolymer obtained by polymerizing this may be a copolymer obtained by polymerizing the raw material monomer and another monomer. That is, the specific polymer has a repeating unit containing a skeleton derived from dehydroabietic acid in its molecular structure.

Here, in the present invention, the “skeleton derived from dehydroabietic acid” only needs to have a structure derived from the above-mentioned dehydroabietic acid, in other words, dehydroabietic acid within a range where a desired effect is achieved. Any structural skeleton that can be derivatized from the above is acceptable. Preferable examples include the following.

“The skeleton derived from dehydroabietic acid” may further have a substituent. Examples of the substituent that may be included include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, a carbonyl group, a nitro group, and an amino group.

(AA-1), (AA-3), and (AA-10) are preferable, and (AA-1) is most preferable.

In the specific polymer of the present invention, it is preferable to include a structure represented by the following formula (U) as a skeleton derived from the dehydroabietic acid.

R ^A and R ^B represent an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 1 to 6 carbon atoms. n represents 0-3. m represents 0-5. Ring Cy represents a saturated or unsaturated 6-membered or 7-membered ring which may contain a hetero atom. In the formula, * and ** represent a bond incorporated into the main chain. * May be a bond extending from ^RA . R ^B is preferably a methyl group. R ^A is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably an i-propyl group. Cy is preferably a cyclohexane ring or a cyclohexene ring, and more preferably a cyclohexane ring. n and m are preferably 1.

The above formula (U) is preferably the following formula (U1). R ^A , R ^B , m, and n are as defined in the above formula (U). R ^C has the same meaning as R ^B. p is an integer of 0 to 2, and is preferably 0.

Furthermore, the above formula (U) is preferably the following formula (U2).

In the formula, * and ** represent a bond.

Dehydroabietic acid is one of the components constituting rosin contained in pine resin of plant origin. That is, since a material of natural origin can be used as its substrate, it is offset in the amount of carbon dioxide emission, and the equivalent emission amount can be greatly reduced as compared with a plastic material of fossil fuel origin. It is an environmentally-friendly material derived from biomass resources that is desired as a next-generation material. The skeleton derived from the above dehydroabietic acid and the skeleton represented by the formulas U, U1 or U2 may be collectively referred to as a dehydroabietane main skeleton, and this may be abbreviated as “DHA main skeleton”. There is.
Furthermore, examples of the skeleton structure important in a preferred embodiment of the present invention include those represented by the following formulas U3 and U4. The thing of the following formula U3 is called a dehydroabietane skeleton (DA skeleton), and the thing of the formula U4 is called a dehydroabietic acid skeleton (DAA skeleton).

The specific polymer is preferably selected from a polymer containing a repeating unit represented by the following formula A01 or A02, more preferably selected from a polymer containing a repeating unit represented by the formula A11 or A12. It is particularly preferable that the polymer is selected from polymers containing a repeating unit represented by A1 or A2. In the following formulae, R ^A , R ^B , R ^C , m, n, and p have the same meanings as the above formulas (U) and (U1). R ^C has the same meaning as R ^B.

In the formula, L ¹¹ , L ¹² , L ²¹ , L ²² , and L ²³ represent a divalent linking group. * Represents a bond. Although the preferable range of these coupling groups is described in description of preferable embodiment of each polymer postscript, when it shows collectively what is preferable, it is as follows.

(1) When it is a repeating unit derived from polycarboxylic acid L ¹¹ : * -CO-L ¹³ -** or * -L ¹³ -CO-** (L ¹³ represents a linking group. See below for details. )
L ¹² , L ²¹ , L ²² : Carbonyl group L ²³ : Oxygen atom, sulfur atom, carbonyl group, sulfonyl group, alkylene group, alkenylene group, arylene group, or single bond (2) When a repeating unit derived from a polyol L ¹¹ : * -L ^1A -O-** (L ^1A represents a linking group. See below for details.)
L ¹² , L ²¹ , L ²² : * — CH ₂ —O — **
L ²³ is as defined above.

In Formula A1, the linking group L ¹¹ is preferably bonded to the carbon atom shown at the 2-position in the formula. In Expression A2, it is preferred that the linking group L ²³ is bonded to the carbon atom represented by the 2-position and 2'-position in the formula.

The structural unit having the DHA main skeleton may constitute a homopolymer alone, but in the present invention, it is preferred that the copolymer component together constitute a copolymer. Specifically, it is preferable to form a polyester together with the polycarboxylic acid and polyol exemplified below. Preferred examples of the copolymer component include those represented by the following formula (II).

Specific polymer A in the present invention may have a structural unit represented by the following formula (II) as a copolymerization component.

・ G ¹
G ¹ is an alkane linking group (alkanediyl, alkanetriyl, alkanetetrayl, etc.), an alkene linking group (alkenediyl, alkenetriyl, alkenetetrayl, etc.), an aryl linking group (aryldiyl, aryltriyl, aryltetrayl, etc.) ), A heteroaryl linking group (heteroaryldiyl, heteroaryltriyl, heteroaryltetrayl, etc.). When G ¹ is an alkane linking group, a combination thereof, or an alkene linking group, it may be chained or cyclic, and when it is chained, it may be linear or branched. One or more hydrogen atoms of the alkane linking group, alkene linking group, aryl linking group, or heteroaryl linking group may be substituted with a specific substituent or may be unsubstituted. Examples of the substituent when substituted include the substituent T described later, and among them, an alkyl group and an alkenyl group are preferable. In addition, one or more carbon atoms constituting the alkane linking group and the alkene linking group may be substituted with a heteroatom, and examples of the heteroatom when substituted include an oxygen atom, a nitrogen atom, and a sulfur atom. Of these, an oxygen atom is preferable (typically, a part of the alkylene chain is linked to an ether bond and linked). In addition, carbon number means that the number of carbon atoms is not included when it has a substituent.

When G ¹ is an alkane linking group (preferably an alkylene group) or an alkene linking group (preferably an alkenylene group), it preferably has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms. The alkylene group and alkenylene group may be substituted or unsubstituted, and a part thereof may be substituted with a hetero atom as described above. More specifically, — (CH ₂ ) ₄ —, — (CH ₂ ) ₅ —, — (CH ₂ ) ₈ —, — (CH ₂ ) ₁₀ —, — (CHRa) CH ₂ —, —CH ₂ — Rb—CH ₂ —, — (CH ₂ CH ₂ O) ₂ —CH ₂ CH ₂ —, and — (CH ₂ CH ₂ O) ₃ —CH ₂ CH ₂ — are more preferred. Ra is preferably an alkyl group or an alkenyl group having 6 to 18 carbon atoms, and C ₁₈ H ₃₇ , C ₁₆ H ₃₃ , C ₁₂ H ₂₅ , C ₈ H ₁₇ , C ₁₈ H ₃₅ , C ₁₆ H ₃₁ , C ₁₂ H _23, and more preferably _C 8 _{H 15.} Rb is preferably a cycloalkylene group having 4 to 12 carbon atoms, and more preferably a cyclohexanediyl group.

When G ¹ is an aryl linking group (preferably an arylene group) or a heteroaryl linking group (preferably a heteroarylene group), it preferably has 3 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Specific examples include a substituted or unsubstituted benzene linking group (preferably a phenylene group). G ¹ may be a linking group obtained by combining an alkane linking group, an alkene linking group, an aryl linking group, and a heteroaryl linking group. For example, a linking group in which an alkane linking group (preferably an alkylene group) and an aryl linking group (preferably an arylene group) are combined and the like may be mentioned. -Ph-Me-Ph- (Ph: phenylene group, Me: methylene group) ), -Ph-Pr-Ph- (Ph: phenylene group, Pr: propane-2,2-diyl group).

・ X, Y, Z
X, Y and Z are each independently —O—, —S—, —NR—, — (C═O) —, —O (C═O) —, — (C═O) O—, — ( C═O) NR— and a divalent linking group selected from the group consisting of combinations thereof. Preferred is —O—, — (C═O) O—, — (C═O) NH—, or — (C═O) —. R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 24 carbon atoms.

・ Mz
mz represents an integer of 0 to 3.

When the formula (II) is derived from a polyol, those represented by the following formula (II-1) are preferable.

When the formula (II) is derived from a polycarboxylic acid, those represented by the following formula (II-2) are preferred.

When the formula (II) is derived from a polyamine, those represented by the following formula (II-3) are preferable.

The copolymer component preferably includes a ring structure, and preferably has an aromatic or aromatic heterocyclic structure. It is preferred that the ring structure is present within the predetermined linking group G ^1. In the present specification, the term “linking group” broadly means that connects two structural portions, and is used in the sense of including atoms and single bonds.

(Molecular weight etc.)
As long as the specific polymer in the present invention includes the DHA main skeleton so as to constitute a part of the main chain, the bonding mode is not particularly limited. The weight average molecular weight of the specific polymer is not limited, but is preferably 5,000 to 700,000, more preferably 10,000 to 500,000. When the weight average molecular weight is within this range, heat resistance suitable for the reflector is realized and improved. In addition, the weight average molecular weight in this invention is the value obtained by the molecular weight measurement (polystyrene conversion) by gel permeation chromatography (GPC). In this specification, unless otherwise specified, molecular weight is determined using N-methyl-2-pyrrolidone as a carrier and TSK-gel Super AWM-H (trade name) manufactured by Tosoh Corporation as a column. Indicates.

The glass transition temperature (Tg) is not limited, but is preferably 100 ° C. or higher, more preferably 150 to 400 ° C., and still more preferably 150 to 350 ° C. When the glass transition temperature is within this range, the polyester polymer is particularly excellent in heat resistance and can be suitably used for a reflector. When the sample is a powder, the glass transition temperature is determined using a differential scanning calorimeter (DSC) in a temperature range of 30 to 400 ° C. under a nitrogen stream at a rate of 10 ° C./min. Measure under the following conditions. Specifically, the intersection of the baseline before and after the transition and the tangent of the maximum slope of the transition slope, as shown on pages 48 to 49 of the 5th edition, Volume 6 of the Experimental Chemistry Course (Chemical Society of Japan, published by Maruzen Co., Ltd.) The extrapolated glass transition start temperature and extrapolated glass transition end temperature are read from the above. Further, the midpoint glass transition temperature is read from the midpoint of the transition, and this is defined as Tg in the present case when the sample is powder. In the present invention, instead of the above, as described later, a dynamic viscoelasticity measuring device (DMA) may be used to measure the Tg of the film and define it as Tg. Unless otherwise specified, the Tg of the film is determined by the method and conditions described in the examples below.

The density of the specific polymer is not limited, but is preferably 1.4 g / cm ³ or less, more preferably 0.80 g / cm ³ to 1.3 g / cm ³ , and still more preferably 0.9 g / cm ³ to 1. .25 g / cm ³ . When the density is within this range, high adhesion and folding resistance are realized, which is favorable for use in a flexible printed circuit board or the like. In addition, the density of a polyester-type polymer says the value measured at 25 degreeC using a precision hydrometer (the SHIMAZU company make, brand name: precision hydrometer AUW120D). In addition, the density here is synonymous with the density (A) of the non-porous film shape | molded by the hot press demonstrated by the porosity mentioned later.

The specific polymer includes derivatives obtained by further subjecting a polymer having a repeating unit containing a DHA main skeleton to chemical treatment.

The DHA main skeleton constituting the specific polymer or a repeating unit having a dimer skeleton thereof (for example, the total content of the repeating unit represented by the formula (A1) and the repeating unit represented by the formula (A2) is particularly Although not limited, from the viewpoint of heat resistance and density, the total amount of the structural part constituting the repeating unit (for example, the total amount of the repeating unit derived from the polycarboxylic acid compound and the repeating unit derived from the polyol compound of the ester polymer below), It is preferably 10 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, and further preferably 40 mol% or more.

The specific polymer may be a copolymer containing at least one other repeating unit that does not contain the DHA main skeleton, if necessary.

In this specification, when a molecule or its structure is specified by adding “compound” at the end, etc., it is used to mean a salt, a complex, or an ion in addition to the compound itself. In addition, it is meant to include a derivative with a predetermined substituent or modified in a predetermined form within a range where a desired effect is exhibited. In the present specification, when a specific group of atoms is referred to with the word “group” added to the end of a substituent or a linking group, it means that the group may have an arbitrary substituent. Examples of the substituent that may be further included in the linking group include the following substituent T.

Examples of the substituent T include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms such as vinyl, allyl, oleyl and the like), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms such as ethynyl, butadiynyl, phenylethynyl and the like), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, Phenyl, 1-naphthyl, 4-methoxyphenyl, -Chlorophenyl, 3-methylphenyl, etc.), heterocyclic groups (preferably heterocyclic groups of 2 to 20 carbon atoms, preferably 5- or 6-membered heterocycles having at least one oxygen atom, sulfur atom, nitrogen atom) A cyclic group is preferred, for example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, Methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), An alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms) Nyl groups such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl and the like, amino groups (preferably containing an amino group having 0 to 20 carbon atoms, alkylamino group, arylamino group, such as amino, N, N-dimethyl) Amino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfonamido groups having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl) Etc.), an acyl group (preferably an acyl group having 1 to 20 carbon atoms such as acetyl, propionyl, butyryl, benzoyl etc.), an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms such as acetyloxy, Benzoyloxy, etc.), carbamoyl groups (preferably those having 1 to 20 carbon atoms) Rubamoyl groups such as N, N-dimethylcarbamoyl and N-phenylcarbamoyl), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms such as acetylamino and benzoylamino), sulfonamide groups (preferably Is a sulfamoyl group having 0 to 20 carbon atoms, such as methanesulfonamide, benzenesulfonamide, N-methylmethanesulfonamide, N-ethylbenzenesulfonamide, etc., an alkylthio group (preferably an alkylthio having 1 to 20 carbon atoms) Groups such as methylthio, ethylthio, isopropylthio, benzylthio, etc., arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio ), An alkyl or arylsulfonyl group (preferably an alkyl or arylsulfonyl group having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, benzenesulfonyl, etc.), a hydroxyl group, a cyano group, a halogen atom (such as a fluorine atom, chlorine) Atoms, bromine atoms, iodine atoms, etc.), more preferably alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, amino groups, acylamino groups, hydroxyl groups or halogen atoms. And particularly preferably an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a hydroxyl group.
In addition, each of the groups listed as the substituent T may be further substituted with the substituent T described above.

When the compound or substituent / linking group contains an alkyl group / alkylene group, alkenyl group / alkenylene group, etc., these may be cyclic or chain-like, and may be linear or branched, and substituted as described above. It may be substituted or unsubstituted. Moreover, when an aryl group, a heterocyclic group, etc. are included, they may be monocyclic or condensed and may be similarly substituted or unsubstituted.

(Connected form)
There are five linking groups L ¹¹ , L ¹² , L ²¹ , L ²² , and L ²³ in Formulas A01, A11, A1 (hereinafter Formula A1 and the like), A02, A12, and A2 (hereinafter Formula A2 and the like). ^but for the four connecting group other than ^{L 23,} (1) polyester-based polymer [I], those respectively preferred in the two (2) polyester-based polymer [II] different. Among these, in the present invention, (1) a polyester polymer is preferable in that high performance is obtained, and the contents of a preferable linking group will be described below in that order. In the present specification, the polyester may have an oxycarbonyl group as a linking group and may have a polycarbonate structure.

(1) Polyester polymer [I]
<Repeating unit derived from dicarboxylic acid compound>
~ Repeating unit represented by Formula A1 ~
・ L ¹¹
L ^{11 in the} formula A1 and the like is * -CO-L ¹³ -** or * -L ¹³ -CO-** (* is 5, 6, 7, 8, 9, 10-hexahydrophenanthrene ring (mother nucleus). ) Represents a bond on the side, and ** represents a bond on the opposite side. L ¹³ is preferably an alkylene group, an alkenylene group, an alkynylene group, an arylene group, an oxygen atom, a carbonyl group, or a single bond. In this specification, the term “linking group” is used in the sense of including an atom or a single bond as long as it connects two structural parts.

The alkylene group and alkenylene group may be linear or branched, or cyclic. L ¹³ is an alkylene group having 2 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 18 carbon atoms, an oxygen atom, a carbonyl group, a single bond, or a single bond thereof, from the viewpoint of heat resistance A combination is preferred. More preferably, it is a chain alkylene group or carbonylalkylene group having 2 to 4 carbon atoms, a cyclic alkylene group or carbonylalkylene group having 5 to 6 carbon atoms, or a chain alkenylene group or carbonylalkenylene group having 2 to 4 carbon atoms. A cyclic alkenylene group or a carbonylalkenylene group having 5 to 6 carbon atoms, an arylene group or carbonylarylene group having 6 to 10 carbon atoms, an oxygen atom, or a single bond.

Specific examples of the linking group represented by L ¹³ include the following, but the present invention is not construed as being limited thereto. In the following exemplary chemical structural formulas, the bond * is the side bonded to the hydrophenanthrene ring, and the bond ** means the opposite side.

L ¹³ in formula (A1) and the like is preferably a single bond, (L1-ex-4), (L1-ex-10) or (Ll-ex-12) from the viewpoint of heat resistance. More preferably, it is a bond.

In the formula A1 and the like, the linking group L ¹¹ may be bonded to any of the carbon atoms at the 1-position, 2-position, and 4-position in the formula, but is bonded to the carbon atom shown at the 2-position or 4-position. It is preferable that it is a thing couple | bonded with the carbon atom shown by 2-position. This bonding position is the same as in (2) polyester polymer [II] described later. The position numbers of the carbon atoms in the above formula correspond to the 11th position, the 2nd position is the 12th position, the 3rd position is the 13th position, and the 4th position is the 14th position with respect to the position number of the abietane.

・ L ¹²
L ¹² is preferably a carbonyl group or a carbonyloxy group. In other words, in the embodiment according to the polyester-based polymer [I], the DHA main skeleton constitutes the DAA skeleton.

Another preferred embodiment of the polyester-based polymer [I] is that a dimer structure in which two dehydroabietane main skeletons are bonded directly or via a linking group is repeated as a part of the main chain. It is included in the unit. The repeating unit containing this dimer structure is represented by the above formula (A2), for example.

~ Repeating unit represented by Formula A2 ~
· ^{L 21, L 22}
L ²¹ and L ^{22 in} formula A2 and the like are preferably a carbonyl group or a carbonyloxy group. This means that the specific polymer of this embodiment has a repeating unit containing a DAA skeleton, like L ¹² above.

・ L ²³
L ²³ is preferably an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, an alkylene group, an alkenylene group, an arylene group, or a single bond. The alkylene group and alkenylene group may be linear or branched, or cyclic. From the viewpoint of heat resistance, the linking group represented by L ²³ is a single bond, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, an alkylene group having 2 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, and It is preferably composed of at least one selected from the group consisting of an arylene group having 6 to 18 carbon atoms, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a chain alkylene group having 2 to 4 carbon atoms, Selected from the group consisting of a cyclic alkylene group having 5 to 6 carbon atoms, a chain alkenylene group having 2 to 4 carbon atoms, a cyclic alkenylene group having 5 to 6 carbon atoms, and an arylene group having 6 to 8 carbon atoms. More preferably, it is a divalent linking group composed of at least one kind, or a single bond.

The alkylene group, alkenylene group and arylene group constituting the linking group represented by L ²³ may have a substituent, if possible. Examples of the substituent in the alkylene group, alkenylene group, and arylene group include the substituent T. Specific examples of the linking group represented by L ^23, may be mentioned the following linking groups, the present invention is not limited thereto.

L ²³ is preferably (L2-ex-2), (L2-ex-5), (L2-ex-9) or (L2-ex-11) from the viewpoint of heat resistance, and (L2 -Ex-2) is more preferable.

In the formula A2 and the like, the linking group L ¹¹ may be bonded to any carbon atom in the 1-position, 2-position, 4-position, 1′-position, 2′-position, and 4′-position in the formula. Preferred are those bonded to the carbon atoms shown in the 4th, 4th, 2 'and 4' positions (however, it is a combination connecting two hydrophenanthrene rings), and the 2nd and 2 'positions. More preferably, it is bonded to the carbon atom represented by This bonding position is also the same for the (2) polyester polymer [II] described later.

In the repeating unit derived from the polycarboxylic acid compound constituting the polyester polymer [I], a repeating unit comprising a DHA main skeleton or a dimer skeleton thereof (for example, the repeating unit represented by the formula (A1) and the formula ( The total content of the repeating unit represented by A2) is not particularly limited, but when the total amount of the repeating unit derived from the dicarboxylic acid compound is 50 mol%, it is 10 mol% or more from the viewpoint of heat resistance and density. It is preferably 15 mol% or more, more preferably 20 mol% or more. In addition, the content rate of the structural unit derived from polycarboxylic acid in polyester is 50 mol% normally, and it becomes an upper limit typically.

The polyester polymer [I] of this embodiment may be a copolymer with other polycarboxylic acid compounds. As the other polycarboxylic acid compound, a polycarboxylic acid compound usually used for constituting the polyester-based polymer [I] can be used without particular limitation. For example, synthetic polymer V (Asakura Shoten) P.I. The polycarboxylic acid compounds described in 63-91 and the like can be used.

Examples of other polycarboxylic acid compounds include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, dicyclohexanedicarboxylic acid, and adipic acid. The content of the repeating unit derived from the other polycarboxylic acid compound in the polyester polymer [I] is not particularly limited as long as the effects of the present invention are not impaired. For example, the content of the repeating units derived from other polycarboxylic acid compounds is preferably 40 mol% or less in the repeating units derived from the polycarboxylic acid compounds constituting the polyester polymer [I]. More preferably, it is at most mol%.

<Repeating unit derived from polyol compound>
-Polyol compound containing a ring structure The polyester polymer [I] of the present embodiment preferably contains the above-mentioned copolymerization component (formula II, II-1) as a repeating unit derived from a polyol compound. Among these, it is preferable that the copolymer component contains at least one repeating unit derived from a polyol compound having a ring structure. The ring structure included in the polyol compound may be included in the side chain portion of the polyester polymer [I] or may be included so as to constitute a part of the main chain. Therefore, the ring structure contained in the polyol compound preferably constitutes a part of the main chain. This further improves heat resistance.

The ring structure contained in the polyol compound may be an aliphatic ring or an aromatic ring, and may be a hydrocarbon ring or a heterocyclic ring. Further, the aliphatic ring may contain an unsaturated bond. The number of rings contained in the polyol compound is not particularly limited, but may be, for example, 1 to 5, preferably 1 to 3, and more preferably 1 to 2 from the viewpoint of heat resistance. When the polyol compound includes two or more ring structures, the structure may be a structure in which two or more monocycles are linked by a covalent bond or a linking group, or may be a condensed ring structure.

Specific examples of the repeating unit derived from the polyol compound having a ring structure include, for example, cyclohexanediol, cyclohexanedimethanol, 1,4-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxypropoxy). Examples thereof include a repeating unit derived from benzene, 4-hydroxyethylphenol, and the like, and a repeating unit derived from a diol compound represented by the following formula (B1). The repeating unit derived from a polyol compound having a ring structure is preferably a repeating unit derived from a polyol compound represented by the following formula (B1) from the viewpoint of heat resistance.

In Formula (B1), L ³ represents a divalent linking group composed of at least one selected from the group consisting of an oxygen atom, a carbonyl group, a sulfonyl group, and an alkylene group, or a single bond. When a plurality of L ³ are present, each L ³ may be the same or different. R ¹ and R ² each independently represent a substituent selected from the group consisting of a halogen atom, an alkyl group, and an alkoxy group, and may be bonded to each other to form a ring. When a plurality of R ¹ and R ² are present, each R ¹ and R ² may be the same or different. n1 and n2 each independently represent an integer from 0 to 4, and n3 represents an integer from 0 to 2.

The alkylene group constituting the divalent linking group in L ³ may be a linear or branched chain alkylene group or a cyclic alkylene group. In addition, the number of carbon atoms of the alkylene group is preferably 1 to 6 and more preferably 1 to 4 from the viewpoint of heat resistance. Note that the carbon number of the alkylene group here does not include the carbon number of the substituent described later. Furthermore, the alkylene group may have a substituent such as a linear or cyclic alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or the like. The number of substituents in the alkylene group may be two or more. When the alkylene group has two or more substituents, the two or more substituents may be the same or different, and are connected to each other to form a ring. May be.

R ¹ and R ² each independently represents a substituent selected from the group consisting of a halogen atom, an alkyl group, and an alkoxy group, but from the viewpoint of heat resistance, a fluorine atom, a chlorine atom, a carbon number of 1 to 8 A substituent selected from the group consisting of an alkyl group and an alkoxy group having 1 to 8 carbon atoms is preferable.

N1 and n2 each independently represents an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0. n3 represents an integer of 0 to 2, and is preferably 0 or 1.

Specific examples of the repeating unit represented by the formula (B1) are shown below, but the present invention is not limited thereto.

As the repeating unit represented by the formula (B1), from the viewpoint of heat resistance, the above (B1-ex-1), (B1-ex-2), (B1-ex-3), (B1-ex-4) ), (B1-ex-5), (B1-ex-6), (B1-ex-7) (B1-ex-9) or (B1-ex-11). Ex-1), (B1-ex-2) or (B1-ex-3) is more preferable.

The content of the repeating unit represented by the formula (B1) in the repeating unit derived from the polyol compound constituting the polyester polymer [I] is not particularly limited, but the total amount of the repeating unit derived from the polyol compound is 50 mol. %, From the viewpoint of heat resistance and density, it is preferably 10 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, and more preferably 40 mol% or more. More preferably it is.

-Polyol compound not containing a ring structure The polyester-based polymer [I] may contain at least one repeating unit derived from another polyol compound not containing a ring structure. As the polyol compound not containing a ring structure, a polyol compound usually used for constituting the polyester polymer [I] can be used without particular limitation, and examples thereof include ethylene glycol, 1,2-propanediol, 1, 3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc. And diol compounds.
In the polyester polymer [I], the content of the repeating unit derived from a polyol compound not containing a ring structure is the same as that containing the ring structure in its preferred range.

The polyester polymer [I] of the present embodiment is preferably a combination having at least one of the following structures as a repeating unit derived from a polycarboxylic acid compound from the viewpoint of heat resistance.

A repeating unit derived from a polycarboxylic acid compound (A1)... L ¹¹ is a carbonyl group, chemical formula (L1-ex-4), (L1-ex-10) or (L1-ex-12), and L ¹² is Carbonyl group Formula (A2)... L ²³ is represented by the chemical formula (L2-ex-2), (L2-ex-5), (L2-ex-9) or (L2-ex-11), L ²¹ and L ²² Is a repeating unit derived from a carbonyl group / polyol compound (B1-ex-1), (B1-ex-2), (B1-ex-3), (B1-ex-4), (B1-ex-5) , (B1-ex-6) or (B1-ex-11)

More preferably, it is the following.
・ Repeating unit derived from polycarboxylic acid compound Formula (A1)... L ¹¹ is a carbonyl group Formula (A2)... L ²³ is (L2-ex-2), L ²¹ and L ²² are carbonyl groups and a polyol compound Repeating unit derived from chemical formula (B1-ex-1), (B1-ex-2), (B1-ex-3) or (B1-ex-4)

The content ratio of the repeating unit derived from the dicarboxylic acid compound and the repeating unit derived from the diol compound constituting the polyester polymer [I] of the present embodiment (repeating unit derived from the dicarboxylic acid compound: repeating unit derived from the diamine compound) is particularly Although not limited, it is usually 1: 1.

(Method for producing polyester polymer [I])
The dehydroabietic acid used in the production of the polyester polymer [I] of the present embodiment can be obtained from rosin, for example. The constituents contained in rosin vary depending on the method of collection and the place of production of the pine, but specifically, abietic acid (1), neoabietic acid (2), parastrinic acid (3), levopimaric acid (4), dehydro It is a mixture of diterpene resin acids such as abietic acid (5), pimaric acid (6) and isopimaric acid (7). Among these diterpene resin acids, each compound represented by (1) to (4) is disproportionated by heat treatment in the presence of a certain kind of metal catalyst, and dehydroabietic acid (5) And dihydroabietic acid (8) having the following structure. That is, the dehydroabietic acid (5) necessary for producing the polyester polymer [I] of the present invention can be obtained relatively easily by subjecting rosin, which is a mixture of various resin acids, to an appropriate chemical treatment. And can be manufactured industrially at low cost. Dihydroabietic acid (8) and dehydroabietic acid (5) can be easily separated by a known method.

For example, the step of synthesizing the polyester polymer [I] having the repeating unit represented by the above formula (A1) or (A2) and the repeating unit represented by the formula (B1) is represented by the formula (B1). The diol compound forming a repeating unit and the dicarboxylic acid compound forming the repeating unit represented by the above formula (A1) or (A2) or a dicarboxylic acid halide derivative or a diester derivative thereof as a derivative are overlapped by a known method. It can be synthesized by condensation. This series of steps can be divided into two types of schemes 1 and 2 below. The following reaction scheme is an example in the present invention, and the present invention is not construed as being limited by this description.

Specific methods for synthesizing polymers include, for example, the methods described in New Polymer Experimental Science 3, Polymer Synthesis / Reaction (2), pp. 78-95, Kyoritsu Publishing (1996) (for example, transesterification method). , Direct esterification method, melt polymerization method such as acid halide method, low-frequency solution polymerization method, high temperature solution polycondensation method, interfacial polycondensation method, etc.). In the present invention, acid chloride method and interfacial polycondensation method are particularly suitable. Preferably used.

The transesterification method is a method of synthesizing a polyester-based polymer [I] by subjecting a polyol compound and a polycarboxylic acid ester derivative in a molten state or a solution state to dealcoholization polycondensation by heating in the presence of a catalyst if necessary. is there.

The direct esterification method is a method of synthesizing a polyester polymer [I] by dehydrating polycondensation of a polyol compound and a polycarboxylic acid compound in the presence of a catalyst in a molten state or a solution state under heating.

In the acid halide method, a polyester polymer [I] is synthesized by heating a polyol compound and a polycarboxylic acid halide derivative in a molten state or in a solution state, if necessary, in the presence of a catalyst and dehydrohalogenating polycondensation. Is the method.

In the interfacial polymerization method, a polyester compound [I] is prepared by dissolving a polyol compound in water, the polycarboxylic acid compound or a derivative thereof in an organic solvent, and polycondensing at a water / organic solvent interface using a phase transfer catalyst. ].

The dimer of dehydroabietic acid (DAA) in Scheme 2 can be synthesized by the method described in JP2011-26569A. Specifically, when connecting the L ²³ represents a single bond, can be advanced a catalytic amount of N, the reaction by the addition of N- dimethylformamide with oxalyl chloride. When L ²³ is a methylene group, a method of replacing the oxalyl chloride with dichloromethane is exemplified. Alternatively, as in the following synthesis example, DAA may be mixed with formalin and the reaction may be advanced by adding a catalytic amount of trifluoroacetic acid.

(2) Polyester polymer [II]
In the present embodiment, the linking groups are preferably as follows.
・ L ¹¹
L ¹¹ is a single bond or * -L ^1A -O-**. * Represents a bond on the hydrophenanthrene ring side, and ** represents the opposite bond. The single bond or divalent linking group represented by L ^1A is not particularly limited, and examples of the linking group include — (C _n H _2n ) —, —CO (C _n H _2n ) —, (here N is an integer of 1 to 12, preferably 1 to 8, which may be linear, branched or cyclic, and may further have a substituent, and may be one of the carbon atoms constituting the molecular chain. One or more may be replaced with an oxygen atom). When the atom bonded to L ^1A is an oxygen atom, it is preferably — (CH ₂ ) ₄ —, — (CH ₂ ) ₅ —, or — (CH ₂ ) ₆ —. When the atom bonded to L ^1A is a carbonyl group, preferably — (CH ₂ ) ₃ —, — (CH ₂ ) ₄ —, — (CH ₂ ) ₅ —, —CO (CH ₂ ) ₂ —, —CO ( CH ₂ ) ₃ —, —CO (CH ₂ ) ₄ — and the like.

^{· L 12, L 21, L} 22
L ¹² is * —CH ₂ —O — **. * Represents a bond on the hydrophenanthrene ring side, and ** represents the opposite bond.
・ L ²³
L ²³ is (1) has the same meaning as ^{L 23} in the polyester polymer [I], the preferred range is also the same.

(Production method of polyester polymer [II])
The polymer of this embodiment is compoundable by the following scheme 3, for example. The following are examples of reaction pathways, and the present invention is not construed as being limited thereto. In addition, although the following has illustrated the aspect shown by the said Formula (A1), since it is the same except making it a dimer which has two abietan main frame | skeleton, it abbreviate | omits about the thing of Formula (A2). The dimerization is the same as in the case of the polyester polymer [I].

(I) The dicarboxylic acid compound can be synthesized in the same manner as (I) of the polyester. The reaction from the dicarboxy compound (i) in which a carboxy group is introduced into abietic acid to the dimethylol compound (ii) may be performed by a normal reduction reaction. For example, the reduction reaction can be rapidly advanced by reducing with aluminum hydride. For the reaction for obtaining the polyester (iii) by reaction with the polycarboxylic acid chloride compound from the dimethylol compound (ii), reference can be made, for example, to the synthesis examples described later.

JP, 2011-026569, A can refer to the above-mentioned (1) manufacturing method of polyester polymer [I], and the details of a compound. (2) For details of the production method and compounds of the polyester-based polymer [II], JP-A-2011-074249 can be referred to.

[Porous membrane]
The porous film of the present invention contains the specific polymer and has pores therein. Here, the term “hole” refers to a hole (hole) that is surrounded by a resin partition and includes air. The holes are preferably independent holes. The independent hole means a hole closed by a resin partition (no gap), and does not include a through hole. The independent holes are preferable because light can be efficiently scattered.

(Characteristics of porous membrane)
-Average pore diameter When the average pore diameter is too large, the incident light penetrates into the light reflector or the number of irregular reflections at the bubble interface decreases, so that the diffuse reflectance tends to decrease. In particular, when a sheet-like reflecting plate is used in a backlight device of a liquid crystal display device, the amount of light returning to the reflecting plate surface is reduced due to light loss from the end of the reflecting plate, so that the diffuse reflectance is lowered. The average pore diameter is preferably 50 μm or less, and more preferably 30 μm or less. In addition, since incident light permeate | transmits when an average bubble diameter (average hole diameter) becomes smaller than the wavelength of visible light, it is necessary for an average hole diameter to be more than the wavelength of visible light at least. The average pore diameter is preferably 0.5 μm or more. If it is smaller than this, light may be transmitted without being scattered. More preferably, it is 1 μm or more. The average pore diameter in the present invention refers to a value obtained by observing a cross section with an SEM, randomly selecting 20 voids, and averaging the diameters.

-Film thickness If the thickness of the porous film is too thin, when used as a reflector, even if other requirements are satisfied, light leakage to the back surface of the light reflector increases, resulting in a decrease in diffuse reflectance. Moreover, when the thickness of the porous film is too thin, the shape retainability is inferior when molded into a predetermined shape. The thickness of the porous film is preferably 30 μm or more, more preferably 50 μm or more, and more preferably 100 μm or more. The upper limit of the film thickness is not particularly limited, but when used for a reflector, it is practical that it is 500 μm or less.
The film thickness in the present invention is a value measured with a digital linear gauge DG-525H (manufactured by Ono Sokki Co., Ltd.). The measurement is performed at three locations, and the average value is obtained.

・ Density When the density of the porous film is too high, that is, when the porosity is small, when used as a reflector, even if other requirements are satisfied, it is due to light absorption in the resin part that is not foamed or transparency of the light reflector Since light loss increases due to light transmission or the like, the diffuse reflectance decreases. The density of the porous film is preferably 0.7 g / cm ³ or less, more preferably 0.4 g / cm ³ or less, and particularly preferably 0.3 g / cm ³ or less. Although the minimum of a density does not have a restriction | limiting in particular, It is preferable that it is 0.05 g / cm < ³ > or more from a viewpoint of hold | maintaining an independent hole.
In the present invention, the density is a value measured at 25 ° C. with a precision specific gravity meter AUW120D (manufactured by SHIMADZU).
When determining the porosity of the resin, the density (B) of the porous membrane resin was divided by the density (A) of the nonporous film produced by a hot press method (see, for example, JP-A-2006-229028). Say the value (B / A). These densities are measured at 25 ° C. The density (A) of the nonporous film can be determined as follows.
Using a precision specific gravity meter AUW120D (manufactured by SHIMADZU), calculation is performed from the weight in air and water (buoyancy method).
ρ = (Wa / Wa−Wl) × ρl
ρ: Sample density Wa: Weight of sample measured in air Wl: Weight of sample measured in water Ρl: Water density (25 ° C)
The porosity of the resin constituting the porous film in the present invention is preferably 5 to 99%, more preferably 40 to 95%.

Reflectance The porous film of the present invention preferably has a diffuse reflectance of 90% or more with respect to a wavelength of 300 to 800 nm. More preferably, it is 95% or more. If the reflectance is less than 90%, sufficient brightness may not be obtained when the backlight unit is incorporated.
The reflectance in the present invention is an average of values measured in a wavelength range of 300 to 800 nm with a spectrophotometer (UV-3101C: manufactured by Shimadzu Corporation). In addition, the white board which hardened the fine powder of barium sulfate was used for the standard white board.
Glossiness The glossiness conforms to the definition described in JIS standard Z8741.
The glossiness of the porous film is not particularly limited and can be appropriately selected according to the purpose. When the measurement is performed with incident light having a wavelength of 400 to 800 nm at an incident angle of 60 degrees or less, the glossiness is 50 or more. Preferably, 60 or more is more preferable, 70 or more is further preferable, and 80 or more is particularly preferable. Having such glossiness is preferable because uniform reflection can be obtained.
The glossiness is a value measured using a variable angle glossmeter VG-1001P (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.) under the conditions of 60 ° (°) incidence of light including a wavelength of 400 to 800 nm and 60 ° light reception. To do.

-Heat shrinkage rate The porous film of the present invention has a heat shrinkage rate of 85 ° C in both directions perpendicular to each other, preferably 0.3% or less, more preferably 0.2% or less, and most preferably 0.1% or less. It is. When the heat shrinkage rate is within this range, a porous film having high heat resistance that is not deformed by the heat of the light source when used as a reflector in a backlight unit can be obtained.
The heat shrinkage rate is obtained when a film sample (0.5 cm × 2.0 cm piece) is prepared and heated at 100 ° C. for 5 hours by the tensile load method of TMA (manufactured by Rigaku Corporation, TMA8310) under the condition of a tensile load of 100 mN. The amount of dimensional change is measured and divided by the sample length before the measurement (note that when it shrinks, it shows a negative value, but it is expressed in absolute value).

(Film forming method)
The porous film of the present invention is formed by a solution casting method. Japanese Patent Publication No. 55-38366 can be referred to for the solution casting method.
A method for phase separation from the polymer solution is usually used for the porous membrane, but the method according to the present invention is preferably used. The porous membrane is formed through phase separation (spinodal decomposition) and coacervation. Such a process may be formed in the process of volatilization of a single parent solvent, or may be formed in the process of volatilization of a mixed solvent of the parent solvent / anti-solvent, and may be induced by heat (cooling). In some cases. It is also possible to promote phase separation by induction of a non-solvent in the polymer solution of the parent solvent. Non-solvent induction can be accomplished by exposure to non-solvent vapor or immersion in a non-solvent bath, or a combination of both. Here, the parent solvent is a solvent capable of sufficiently dissolving the specific polymer, the poor solvent is a solvent that does not substantially dissolve the specific polymer but swells, and the non-solvent substantially dissolves and swells the specific polymer. It is a solvent that does not. In addition, if it dares to define each solvent by the physical property, it will be as follows.
Good solvent: Solvent that dissolves 5 to 100% by mass of solute at 25 ° C. Poor solvent: Solvent that dissolves less than 0.1 to 5% by mass of solute at 25 ° C. Non-solvent: Less than 0.1% by mass of solute at 25 ° C. Solvents that do not dissolve (including those that do not dissolve at all)

In the present invention, the parent solvent, the poor solvent, and the non-solvent are relative definitions determined by a dissolving action and a swelling action with respect to a specific polymer. Therefore, such a definition and a specific example of the solvent should be uniquely associated. I can't. That is, depending on the type of the specific polymer used, the types of the parent solvent, the poor solvent, and the non-solvent may be different or may be changed. However, these relationships are based on the chemical and physical properties of the specific polymer, and any person skilled in the art can easily select the specific polymer and three types of solvents based on ordinary knowledge. In this method of the present invention, these relationships need not be particularly problematic. The parent solvent is preferably one that dissolves the polymer. The poor solvent preferably swells the polymer but does not dissolve it. The non-solvent is preferably one that does not swell or does not interfere at all.
The method for dissolving and mixing the specific polymer, the parent solvent, the poor solvent and the non-solvent is not particularly limited. For example, the method of adding the poor solvent and the non-solvent after dissolving the specific polymer in the parent solvent, the specific polymer as the parent solvent There are several tens of methods, such as a method of adding a part of a poor solvent and dissolving, adding the remaining poor solvent to this solution, and further adding a non-solvent, and any of these methods can be used. In addition, there are no special restrictions on the conditions such as the mixing ratio of each solvent, the temperature at the time of mixing (there is a condition that the boiling point of the solvent is preferable). Furthermore, in some cases, one of a poor solvent and a non-solvent may not be used. That is, by using an inorganic salt or the like, a parent solvent may be combined with a poor solvent or a non-solvent. However, if the prepared specific polymer solution is stable, the subsequent operation becomes simple. Therefore, it is desirable to perform dissolution and mixing so as to obtain a stable solution. A stable solution is a solution in which a specific polymer is not gelled or phase-separated in the solution. For this purpose, the amount of the parent solvent in the solvent is larger than the amount of each of the other solvents, or What is necessary is just to employ | adopt means, such as adding and dissolving a specific polymer to the mixture of all the parent solvents, and a part of poor solvent.

Organic solvents used in the specific polymer solution include aromatic hydrocarbons such as xylene and toluene, diphthalyl phthalate, phthalic acid esters such as dimethoxyoxyethyl phthalate and dimethyl phthalate, phosphorus such as triphenyl phosphate, and tricresyl phosphate. Acid esters, glycerol triacetate, polyhydric alcohol esters such as ethyl phthalyl ethyl glycolate or methyl phthalyl ethyl glycolate, mineral oils such as kerosene and kerosene, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, methylene chloride, Halogenated hydrocarbons such as chloroform or 1,1-dichloroethane, esters such as methyl acetate or ethyl acetate, N-methyl-2-pyrrolidone (N P), N, N- dimethyl formamide (DMF), N, and the like such as nitrogen compounds N- dimethylacetamide (DMAc).

These solvents can be used alone or as a mixed solvent of two or more solvents. An appropriate solvent must be selected according to the linking group and degree of polymerization of the specific polymer used. In this specific polymer solution, the specific polymer concentration varies depending on the type of the specific polymer and the type of the solvent, but it is preferable that the concentration is high to some extent from the relationship of forming a continuous porous film, for example, around 15% by mass. preferable. Although the solubility of the specific polymer is not high, it is preferable that the specific polymer is high in terms of forming a film.

The specific polymer solution thus prepared is cast (drawn) to a thickness of 50 to 3000 μm on a support such as a glass plate, a plastic film or a metal plate using an applicator. When phase separation occurs during the volatilization process of the parent solvent or the mixed solvent of the parent solvent / the poor solvent, the porous film can be obtained by peeling and drying the film from the support after the solvent volatilization.
When phase separation is promoted by induction of non- (poor) solvent, after application or after volatilization of a part of the solvent, or after exposure to the vapor of non- (poor) solvent for a certain period of time, ) The whole support is immersed in a solvent to induce phase separation and form a porous membrane. The non-poor solvent has high mutual solubility with the parent solvent, and a poor solvent or a non-solvent is used for the specific polymer. Anything can be used as long as the above requirements are satisfied, but alcohols such as methanol, ethanol or isopropanol, and water are preferable from the viewpoint of ease of handling, low cost, and safety. The temperature of the resin solution during casting is intended to be room temperature, but depending on the solvent system used, it is cast at a high temperature of around 100 ° C and then cooled in air or cooled to room temperature or a low temperature below room temperature. It is also performed by immersing in a liquid and quenching.

[a reflector]
The reflector of the present invention is not particularly limited as long as it uses the porous film of the present invention. Even if it is formed only with the porous membrane, it may have a support.
FIG. 1 shows a schematic perspective view of a backlight of a liquid crystal device using the reflector of the present invention. In the backlight 10, a lamp reflector 5 having the reflective film 1 made of the porous film detailed in the above embodiment on the surface of the reflector base 51 is shown. This is also a broad reflector. In this apparatus, light from the light emitting lamp 4 surrounded by the lamp reflector 5 enters the light guide plate 2 and is sent to the liquid crystal panel through the diffusion plate 3. At this time, in order to reflect and reuse the light leaked downward from the light guide plate 2, the reflection plate 6 composed of the reflection film 1 and the reflection base material 61 is provided. Therefore, according to this embodiment, the high light reflectivity of the reflective film 1 made of a porous film can be obtained, and light can be supplied to the liquid crystal panel more efficiently. In addition, the reflective film of this embodiment withstands heat generated by the light emitting lamp, is resistant to thermal contraction, satisfies such required characteristics of the liquid crystal display device, and functions well.
The usage form of the porous film of the present invention is not limited to the above, and can be suitably used for, for example, a fluorescent lamp, an incandescent lamp, or a light source cover of an LED light, and exhibits the above-described advantages. Reference can be made to JP-A No. 2006-8942, JP-A No. 2009-244749, JP-A No. 2011-25473, and the like for usage forms as such a light source cover.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited thereto.

<Synthesis Example 1> DAA monomer synthesis 1,2-carboxydehydroabietic acid (a-1) used for the synthesis of a dehydroabietic acid polymer was synthesized according to the following synthetic route.

26.8 g of oxalyl chloride was added dropwise at room temperature to a mixture of 60.0 g of 92% dehydroabietic acid (the above chemical formula (A), manufactured by Arakawa Chemical Industries) and 120 ml of methylene chloride. After stirring for 3 hours, the solvent was distilled off under reduced pressure, and 32.0 g of methanol was added dropwise thereto. After stirring at room temperature for 3 hours, excess methanol was distilled off under reduced pressure to obtain 62.8 g of white crystals of compound (B).

To a mixture of 62.8 g of Compound (B), 18.8 g of acetyl chloride and 160 ml of methylene chloride, 58.6 g of anhydrous aluminum chloride was added in small portions at 3 to 5 ° C. After stirring at 5-8 ° C. for 2 hours, the reaction solution was poured into 1000 g of ice water. The organic layer was extracted by adding 400 ml of ethyl acetate. After washing with brine and drying over anhydrous magnesium chloride, the solvent was distilled off under reduced pressure, and 100 ml of cold methanol was added to the residue, and the precipitated white crystals of compound (C) were collected by filtration (yield 65.6 g).

64.0 g of sodium hydroxide was dissolved in 200 ml of water, and 51.2 g of bromine was added dropwise thereto at 8 to 10 ° C. Further, a solution obtained by dissolving 35.6 g of compound (C) in 200 ml of dimethoxyethane was added dropwise at 10 to 12 ° C. After stirring at room temperature for 2 hours, the reaction solution was poured into 6N cold dilute hydrochloric acid to acidify, and the precipitated white crystals were collected by filtration. The crystals were recrystallized from methanol to obtain 29.8 g of compound (D) crystals.

100 g of 10 wt% aqueous sodium hydroxide was added to 20.4 g of compound (D) and stirred. Thereafter, the reaction system was heated at an external temperature of 130 ° C. and gently refluxed. The mixture was stirred for 3 hours as it was, the reaction was checked by thin layer chromatography, and then the temperature of the reaction system was cooled to room temperature. The contents of the reaction system were slowly added to 250 mL of cooled 1N hydrochloric acid to cause acid precipitation. It was filtered with Nutsche and washed with water to neutralize the filtrate. The solid was taken out and dried to obtain 19.2 g of 12-carboxydehydroabietic acid (a-1).

<Synthesis Example 2>

13.76 g of the crystal of compound (a-1) was dispersed in 160 ml of methylene chloride, 11.18 g of oxalyl chloride and 0.6 ml of dimethylformamide were added, and the mixture was heated to reflux for 5 hours. During this time, the crystals were completely dissolved. After allowing to cool, the solvent was distilled off under reduced pressure, 20 ml of ethyl acetate and 60 ml of n-hexane were added to the residue, and a white precipitate of acid chloride (a-1 ') of compound (a-1) was collected by filtration and dried under reduced pressure. Yield was 13 g.

Dicarboxylic acid (a-2) was synthesized according to the following synthesis route.

200 ml of trifluoroacetic acid was added dropwise at 10 to 15 ° C. to a mixture of 120 g of 92% dehydroabietic acid (the above chemical formula (A), Arakawa Chemical Industries), 20 ml of 36% formalin and 200 ml of methylene chloride. After stirring at 15 to 20 ° C. for 8 hours, methylene chloride and trifluoroacetic acid were distilled off under reduced pressure. 2 l of water was added to the residue, and off-white crystals were filtered and thoroughly washed with water. After drying, 1 l of hot n-hexane was added and stirred for 1 hour. After cooling, white crystals of (a-2) were collected by filtration. The yield was 118g.

<Synthesis Example 3>
A polyester polymer (PE-1) was synthesized according to the following scheme.

Hydroquinone (2.03 g) and N, N-dimethylaminopyridine (7.05 g) were dissolved in N, N-dimethylacetamide (100 ml). The temperature in the system was cooled to 10 ° C., and 10.5 g of the acid chloride derivative (a-1 ′) of the dicarboxylic acid compound (a-1) obtained above was added little by little. The reaction solution gradually became viscous. After stirring at room temperature for 8 hours, 1 L of methanol was added to the reaction solution, and the produced PE-1 was separated by filtration and washed with methanol. The obtained product was dried, dissolved in 100 ml of N, N-dimethylformamide by heating, and poured into 1000 ml of methanol little by little for reprecipitation. The reprecipitate was collected and dried to obtain 10.8 g of a white solid of PE-1. The obtained polyester polymer (dehydroabietic acid polymer, PE-1) had a weight average molecular weight of 95,000 according to GPC measurement (solvent: NMP).

A polyester polymer (PE-2) was synthesized in the same manner as in the synthesis example of PE-1, except that the dicarboxylic acid compound and the diol compound were changed to the compounds shown in Table 1 in Synthesis Example 1, respectively. ) To (PE-10) were obtained. The glass transition temperature in Table 1 is a value obtained by measuring a powder sample with a differential scanning calorimeter (DSC).

In Table 1, the numbers in parentheses in the dicarboxylic acid compound and the diol compound indicate the charged amount (mol%) when the polyester polymer is produced. The total amount of dicarboxylic acid compound and diol compound was 100 mol%. The structures of dicarboxylic acid compounds and diol compounds are shown below.

(Example 1 and Comparative Example 1)
3 g of the polymer PE-1 was dissolved in N-methylpyrrolidone at a concentration of 12% by mass, and this was pressure filtered through a filter paper having a filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63) to prepare a dope ( Test 101).
The prepared dope was cast on a glass substrate with a clearance of 1.0 mm using a doctor blade. After casting, it was exposed to air having a humidity of 85% RH for 5 minutes, and then immersed in a water bath for 30 minutes. The obtained film was vacuum-dried at 120 ° C. and 1 Torr for 3 hours to produce a porous film. The film thickness was 120 μm (0.12 mm). The photograph which observed the obtained film cross section with the electron microscope is shown in FIG. It turns out that it is a porous film | membrane with which the fine independent hole was formed.

3 g of polymer PE-1 was dissolved in a mixed solvent of methylene chloride / methanol (85/15) at a concentration of 12% by mass, and this was pressurized with a filter paper (manufactured by Toyo Filter Paper Co., Ltd., # 63) having a filtration accuracy of 0.01 mm. Filtration was performed to prepare a dope (Test 102).
The prepared dope was cast on a glass substrate with a clearance of 1.0 mm using a doctor blade. After casting, the film was allowed to stand at room temperature for 6 hours, dried by heating at 40 ° C. for 30 minutes and at 100 ° C. for 30 minutes, and then vacuum dried at 140 ° C. and 1 Torr for 1 hour to produce a film. The film thickness was 90 μm (0.09 mm).

A film was produced in the same manner as in the test 102 except that the polymer PE-1 was changed to the polymer shown in the table. The film thickness is shown in Table 1.

3 g of polymer C (cellulose acetate: manufactured by L70 Daicel) was dissolved in a mixed solvent of methylene chloride / methanol (85/15) at a concentration of 12% by mass, and this was dissolved in a filter paper (Toyo Filter Paper Co., Ltd.) having a filtration accuracy of 0.01 mm. , # 63) and filtered under pressure to prepare a dope.
The prepared dope was cast on a glass substrate with a clearance of 1.0 mm using a doctor blade. After casting, the film was allowed to stand at room temperature for 6 hours, dried by heating at 40 ° C. for 30 minutes and at 100 ° C. for 30 minutes, and then vacuum-dried at 140 ° C. and 1 Torr for 1 hour to prepare a film (c11). The film thickness was 120 μm (0.12 mm).

The product name: UXZ1 (thickness 0.23 mm) manufactured by Teijin DuPont, which is a light reflecting film, was used as the reflecting plate of Comparative Example 2. UXZ1 is a biaxially stretched film obtained by mixing PET with barium sulfate (Japanese Patent Laid-Open No. 2011-25473) (c12).

The product name: MCPET (thickness: 1.00 mm) of Furukawa Electric, which is a light reflecting film, was used as the reflector of Comparative Example 3. MCPET is a film obtained by impregnating PET with CO ₂ and foaming it (Japanese Patent Laid-Open No. 2009-244749) (c13).

-Evaluation methods-
The following measurements and evaluations were performed on the films (reflecting plates) of Examples and Comparative Examples.
(Film thickness measurement)
The thickness of the obtained film was measured with a digital linear gauge DG-525H (manufactured by Ono Sokki Co., Ltd.). Measurement was performed at three locations, and the average value was obtained.
(Measurement of density (specific gravity))
The density (specific gravity) of the obtained film was measured at 25 ° C. with a precision specific gravity meter AUW120D (manufactured by SHIMADZU).
(Reflectance)
The reflectance was measured with a spectrophotometer (UV-3101C: manufactured by Shimadzu Corporation) in the wavelength range of 300 to 800 nm. The standard white plate was a white plate hardened with fine barium sulfate powder.
(Glossiness measurement)
Using a variable angle gloss meter VG-1001DP (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.), light with a wavelength of 400 to 800 nm is measured under conditions of 60 ° (°) incidence and 60 ° light reception to obtain a glossiness. It was.
(Glass transition temperature (Tg))
A 5 mm × 22 mm strip test piece was cut out from the obtained film, and this was tangent loss (tan δ) in a temperature range of 25 ° C. to 350 ° C. in a tensile mode using a dynamic viscoelasticity measuring device Rheogel-E4000 (manufactured by UBM). ) Was measured. The temperature at which the tangent loss (tan δ) showed a maximum value was defined as the glass transition temperature (Tg). An example of the reading is shown in FIG.
(Measurement of heat shrinkage)
A film sample (0.5 cm × 2.0 cm piece) was prepared, and the amount of dimensional change when heated at 100 ° C. for 5 hours by the tensile load method of TMA (manufactured by Rigaku Corporation, TMA8310) under the condition of a tensile load of 100 mN. The value obtained by measuring and dividing by the sample length before the measurement was defined as the rate of dimensional change of the film (note that all showed shrinkage change (minus value), but expressed in absolute value).

(Porosity)
When the density of the resin was A and the density of the porous film was B, the porosity was specified as B / A × 100.

(Average pore diameter)
The cross section of the porous film was observed by SEM, and 20 voids were selected at random and the diameters were averaged.

(Independent hole discrimination)
The pore diameter was evaluated by the bubble point method, which is an evaluation of the through-pore diameter of a porous material based on JIS K 3832 and ASTM F316-86. It was judged that it was not a through-hole, that is, an independent hole, with the result that a measured value was not obtained.

(Thermal conductivity)
α = k / ρ · Cp
α: temperature diffusivity k: thermal conductivity (Js ⁻¹ m ⁻¹ K ⁻¹ )
ρ: Density (kg m ⁻³ )
Cp: specific heat capacity (J kg ⁻¹ K ⁻¹ )
The thermal diffusivity was measured using Model LaserPIT manufactured by ULVAC-RIKO, and the specific heat capacity was measured using DSC6200S manufactured by SII to calculate the thermal conductivity.

All the films of the examples have independent holes and high reflectivity. In addition, it has excellent heat resistance such as low thermal shrinkage and low thermal conductivity, and also has excellent properties such that the glass transition temperature is extremely higher than that of the comparative example. All of these films can withstand the heat from the light source and have high reflectivity, so that it can be seen that they are suitable as a reflector.

(Example 2 and Comparative Example 2)
Evaluation tests for reflectance, glossiness, and heat shrinkage were performed in the same manner except that PE-1 used in Test 101 was changed as shown in the following table. As a result, in all the test bodies, the result of “A” was obtained, and it was confirmed that good performance was achieved.
<Performance evaluation>
・ Reflectance and gloss When the result of PE-1 is 100 A: 80 or more B: 60 or more and less than 80 C: Less than 60 ・ Heat shrinkage When the result of PE-1 is 100 A: 5 times or less B : More than 5 times Less than 10 times C: More than 10 times

DESCRIPTION OF SYMBOLS 1 Reflective film 2 Light guide plate 3 Diffusion plate 4 Fluorescent lamp 5 Lamp reflector 6 Reflector 10 Backlight 51 Reflector base material 61 Reflective base material

Claims (15)

1. A porous membrane comprising a specific polymer containing a skeleton derived from dehydroabietic acid as a repeating unit and having pores therein.
2. The porous membrane according to claim 1, wherein the skeleton derived from dehydroabietic acid includes a structure represented by the following formula (U).
   

   

   (R ^A and R ^B represent an alkyl group or alkenyl group having 1 to 6 carbon atoms. N and m represent an integer of 0 to 3. m represents an integer of 0 to 5. Ring Cy represents a hetero atom. A saturated or unsaturated 6-membered ring or 7-membered ring which may be included is represented, wherein * and ** represent a bond incorporated in the main chain, and * may be a bond extending from ^RA . )
3. The porous membrane according to claim 1 or 2, wherein the specific polymer is selected from polymers containing a repeating unit represented by the following formula A1 or A2 in the main chain.
   

   

   (In the formula, L ¹¹ , L ¹² , L ²¹ , L ²² , and L ²³ represent a divalent linking group. * Represents a bond incorporated in the main chain.)
4. The porous membrane according to any one of claims 1 to 3, wherein in the formula A1, the linking group L ¹¹ is bonded to the carbon atom shown at the 2-position in the formula.
5. The porous membrane according to any one of claims 1 to 4, wherein in the formula A2, the linking group L ²³ is bonded to the carbon atoms represented by the 2-position and the 2'-position in the formula.
6. L ^{11 in} Formula A1 is * -L ¹³ -CO-** or * -CO-L ¹³ -** (* represents a bond on the hydrophenanthrene ring side. ** represents the opposite bond. And L ¹³ is an alkylene group, an alkenylene group, an alkynylene group, an arylene group, an oxygen atom, a carbonyl group, or a single bond, and L ¹² is a carbonyl group or a carbonyloxy group. 2. A porous membrane according to 1.
7. L ²¹ and L ^{22 in} formula A2 are a carbonyl group or a carbonyloxy group, and L ²³ is an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, an alkylene group, an alkenylene group, an arylene group, or a single bond. 7. The porous membrane according to any one of 1 to 6.
8. The porous film according to any one of claims 1 to 7, wherein the specific polymer further includes a repeating unit derived from a diol compound containing a ring structure.
9. The hard film according to claim 8, wherein the copolymer component is represented by the following formula (II).
   

   

   [G ¹ represents an alkylene group, an alkenylene group, an arylene group, a heteroarylene group, or a linking group obtained by combining these. X, Y, and Z are each independently —O—, —S—, —NR—, — (C═O) —, —O (C═O) —, — (C═O) O—, — ( C═O) NR— represents a divalent linking group selected from the group consisting of NR— and combinations thereof. R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 24 carbon atoms. * Is a bond incorporated in the main chain. mz is an integer of 0 to 3. R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 24 carbon atoms. ]
10. The porous membrane according to claim 8, wherein the formula (II) is represented by the following formula (B1).
    

    

    (L ³ is an oxygen atom, a carbonyl group, a sulfonyl group, an alkylene group, or a single bond. When a plurality of L ³ are present, each of them may be the same or different. R ¹ and R ² are each Independently, it represents a halogen atom, an alkyl group or an alkoxy group and may be bonded to each other to form a ring, and when a plurality of R ¹ and R ² are present, each may be the same or different. n1 and n2 each independently represents an integer of 0 to 4. n3 represents an integer of 0 to 2. * represents a bond.)
11. The multi-hard film according to any one of claims 1 to 10, wherein the copolymer component includes a ring structure.
12. The porous membrane according to any one of claims 1 to 11, wherein the pores are independent pores having an average pore diameter of 0.5 µm to 50 µm.
13. The porous membrane according to any one of claims 1 to 12, wherein the density of the porous membrane is 0.05 to 0.7 g / cm ³ .
14. The porous membrane according to any one of claims 1 to 13, wherein the pores are produced by a solution casting method using phase separation.
15. A reflector comprising the porous film according to any one of claims 1 to 14.

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