KR20210032458A - Ester resin, semi-plasticizer, cellulose ester resin composition, optical film and liquid crystal display - Google Patents

Abstract

It has excellent balance of strength, heat resistance, and dimensional stability when processed into a film, and can be suitably used as a semi-plasticizer for optical resins, a resin composition containing the same, and obtained by using the resin composition. It provides an optical film and a liquid crystal display device using the same. Specifically,
B ¹ -(G ¹ -A) _n -G ¹ -B ¹
[In the formula, B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is an isophthalic acid residue. , n is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and a plurality of B ¹ and G ¹ may be the same or different], a resin composition containing the same, and the composition The film for optics obtained by using and the liquid crystal display device using the film for optics are used.

Description

Ester resin, semi-plasticizer, cellulose ester resin composition, optical film and liquid crystal display

The present invention relates to an ester resin, an ester resin mixture, and a cellulose ester resin composition containing them suitable as a semi-plasticizer of a resin for optical materials, an optical film obtained by using the resin composition, and a liquid crystal display device using the same.

In recent years, the liquid crystal display is thinning, and the polarizing plate protective film is also thinning from 80 µm to 60 µm, and further to 40 to 25 µm. Conventionally, triacetyl cellulose resin (hereinafter, TAC) has been widely used for the protective film of the polarizing plate from the viewpoint of easy bonding with the polarizer.

However, since TAC is hard and brittle, when it is formed into a film, there is a problem such as insufficient strength, and breakage is likely to occur. In addition, TAC has high moisture permeability and hygroscopicity, and dimensional change due to moisture permeation and moisture is liable to occur, so it is necessary to suppress moisture permeation and moisture absorption with additives, and various additives have been provided (for example, see Patent Document 1). ).

Typically, when an additive is added to suppress moisture permeation or moisture absorption, plasticization of the resin occurs at the same time, so it is difficult to achieve both physical properties such as strength and heat resistance and dimensional stability of the obtained film. Therefore, there is a need to develop an additive capable of providing a film having excellent elastic modulus, heat resistance and dimensional stability.

Japanese Unexamined Patent Publication No. 2013-151699

In view of the above circumstances, the problem to be solved by the present invention is, in particular, excellent balance of strength, heat resistance, and moisture absorption dimensional stability when processed into a film, and can be suitably used as a semi-plasticizer for optical resins. It is to provide an ester resin, an ester resin mixture, a cellulose ester resin composition containing this, an optical film obtained using the resin composition, and a liquid crystal display device using the same.

As a result of intensive investigation, the inventors of the present invention have found that the above problem can be solved by specifying the dicarboxylic acid component in the raw material of the ester resin, and the present invention has been completed.

That is, the present invention is the following general formula (I)

B ¹ -(G ¹ -A) nG ¹ -B ¹ (I)

[In formula (1), B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A This isophthalic acid residue, n is the number of repetitions, and G ¹ and A may be the same or different for ^{each repetition, and a plurality of B 1} and G ¹ may be the same or different]

An ester resin characterized by represented by and an ester resin mixture comprising the same, a semi-plasticizer made of these, a cellulose ester resin composition, an optical film obtained by using the composition, and a liquid crystal display device using the optical film To provide.

According to the present invention, it is possible to provide an ester resin and an ester resin mixture that has excellent balance of strength, heat resistance, and dimensional stability when processed into a film, and which can be suitably used as a semi-plasticizer for an optical resin. In addition, by using the specific ester resin or a mixture thereof, in particular, in an optical film containing a cellulose ester resin, it is possible to improve the elastic modulus, heat resistance, and dimensional stability without impairing transparency, and to achieve a liquid crystal display device. It can be suitably used as an optical film used for.

The ester resin of the present invention is the following general formula (I)

B ¹ -(G ¹ -A) _n -G ¹ -B ¹ (I)

[In formula (1), B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A This isophthalic acid residue, n is the number of repetitions, and G ¹ and A may be the same or different for ^{each repetition, and a plurality of B 1} and G ¹ may be the same or different]

It characterized in that it is represented by.

^{B 1} in the general formula (1) is a monocarboxylic acid residue, and specifically, an aliphatic monocarboxylic acid residue is mentioned. Here, the "carboxylic acid residue" represents a group other than -OH in the carboxyl group. As the aliphatic monocarboxylic acid residue, an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms is a balance of water permeability resistance, elastic modulus, and optical properties when mixed with a cellulose ester resin described later, and the availability of raw materials and the ease of esterification reaction. It is preferable from the viewpoint of being easy to catch, and examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, and octylic acid, and may be used alone or in combination of two or more. It is desirable. In addition, the number of carbon atoms here does not include carbon atoms in the carboxyl group.

^{G 1} in the general formula (I) is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue. The glycol residue represents a group after removing a hydrogen atom from a hydroxyl group.

The alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, ethylene glycol, 1,2-propylene glycol, 1 ,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl1,3-pentanediol, 2-ethyl-1,3-hexane Residues such as diol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, may be used alone or in combination of two or more You can do it. Among these, from the viewpoint of being an ester resin having more excellent compatibility when mixed with a cellulose ester resin described later, it is preferable that the number of carbon atoms not including branches between OH groups is 3 or less, and among them, ethylene glycol, 1,2- It is preferably a residue of propylene glycol, 1,3-propanediol, 1,2-butanediol, and 2-methyl-1,3-propanediol, more preferably a residue of ethylene glycol and 1,2-propylene glycol, Most preferably, it is a residue of 1,2-propylene glycol.

The oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, diethylene glycol, triethylene glycol, tetra Residues such as ethylene glycol, dipropylene glycol, and tripropylene glycol may be mentioned, and may be used alone or in combination of two or more.

The aryl glycol residue is preferably an aryl glycol residue having 6 to 18 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, alkylene oxides of hydroquinone, resorcin, bisphenol A, and bisphenol A. Residues such as an adduct, bisphenol F, an alkylene oxide adduct of bisphenol F, a biphenol, and an alkylene oxide adduct of biphenol may be mentioned, and may be used alone or in combination of two or more.

In addition, A in the general formula (I) is a dicarboxylic acid residue, specifically an alkylenedicarboxylic acid residue (A1) or an aryldicarboxylic acid residue (A2), and the isophthalic acid residue in the total number of moles of A It is essential that the number of forfeitures is 25 mol% or more. Here, the dicarboxylic acid residue refers to a group from which -OH in the carboxyl group has been removed.

In the ester resin represented by the general formula (I), by using a large amount of isophthalic acid as the dicarboxylic acid of the raw material, when mixed with the optical resin described later, the optical resin, especially the cellulose ester resin, is calcined. When processed into a film without conversion, it can be suitably used for an optical film application in which thinning proceeds without impairing the transparency inherent in the optical resin while improving the elastic modulus and imparting heat resistance.

From the viewpoint of exhibiting the above effects, it is essential that the number of moles of isophthalic acid residues in the dicarboxylic acid residues is 25 mol% or more, and in particular, from the viewpoint of showing the effect more, the content of isophthalic acid residues is 25 to 100 mol%. It is preferably in the range of, more preferably in the range of 40 to 100%, and most preferably in the range of 70 to 90%.

As the alkylenedicarboxylic acid residue (A1) which may be shared with an isophthalic acid residue, it is preferable that it is an alkylenedicarboxylic acid residue having 2 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention, for example , Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxycyclohexane, 1,2-dicarboxycyclohexene and the like, and may be used alone, Two or more types may be used in combination. Among these, since an optical film having more excellent transparency of the film is obtained, it is preferable that it is a residue of succinic acid, adipic acid, or 1,2-dicarboxycyclohexane, and a residue of adipic acid is most preferable.

Examples of the aryldicarboxylic acid residue (A2) that may be shared with an isophthalic acid residue include phthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. And residues such as 2,7-naphthalenedicarboxylic acid and 1,8-naphthalenedicarboxylic acid, and may be used alone or in combination of two or more. Among these, since an optical film with higher strength can be obtained, it is preferable that it is a residue of phthalic acid or terephthalic acid, and a residue of phthalic acid is most preferable.

In the present invention, as the ester resin represented by the general formula (I), B ¹ , G ¹ , and A are made of the same, and n, that is, a mixture of compounds different only in the number of repetitions may be used, or the general formula (I ) In B ¹ , G ¹ , A and n may be a mixture of different compounds, respectively.

From the viewpoint of further expressing the effect of the present invention, in the general formula (I), B ¹ is acetic acid, propionic acid, octylic acid residue, G ¹ is ethylene glycol, 1,2-propylene glycol, 1,3-propane Diol, 1,2-butanediol, 2-methyl-1,3-propanediol residue, A1 that may be present in combination is a residue of succinic acid, adipic acid, 1,2-dicarboxycyclohexane, A2 is a phthalic acid, terephthalic acid. It is preferable that it is a residue, and in particular, B ¹ is a residue of acetic acid, G ¹ is a residue of ethylene glycol or 1,2-propylene glycol, and A1 is an adipic acid residue, and A2 is a residue of phthalic acid, which may be coexisted. desirable.

In the present invention, in an optical film obtained by mixing with a resin for an optical material described later, particularly a cellulose ester resin, in order to reduce nonvolatile components in the manufacturing process of the film, and to obtain an optical film having more excellent moisture absorption dimensional stability, It is preferable to reduce the amount of residual glycol in the ester resin represented by the general formula (I) by distillation or the like. As the amount of residual glycol in the ester resin, it is preferable to set it as 1.5 mass% or less, and it is most preferable to set it as 1.0 mass% or less. In addition, the amount of the remaining glycol can be measured by gas chromatography.

Further, as the ester resin of the present invention, the number average molecular weight is preferably in the range of 350 to 2000, particularly preferably in the range of 400 to 1500, and in the range of 500 to 1200 from the viewpoint of making compatibility and film physical properties compatible. It is most preferred. In addition, as the average value of the repetition number n in the general formula (I), similarly, from the viewpoint of achieving both compatibility and film properties, it is preferably in the range of 1.0 to 10.0, more preferably in the range of 1.0 to 8.0, and 1.5 to Most preferably, it is in the range of 7.0. Moreover, this number average molecular weight and the average value of n are values measured by GPC measurement.

In addition, the GPC measurement in the present invention was carried out under the following conditions.

[GPC measurement conditions]

Measuring device: Tosoh Corporation high-speed GPC device "HLC-8320GPC"

Column: Tosoh Corporation ``TSK GURDCOLUMN SuperHZ-L'' + Tosoh Corporation ``TSK gel SuperHZM-M'' + Tosoh Corporation ``TSK gel SuperHZM-M'' + Tosoh Corporation 「TSK gel SuperHZ-2000」 + 「TSK gel SuperHZ-2000」 made by Tosoh Corporation

Detector: RI (differential refractometer)

Data processing: "EcoSEC Data Analysis version 1.07" manufactured by Tosoh Corporation

Column temperature: 40°C

Development solvent: tetrahydrofuran

Flow rate: 0.35mL/min

Measurement sample: 7.5 mg of a sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered through a micro filter to obtain a measurement sample.

Sample injection volume: 20μl

Standard sample: In accordance with the measurement manual of "HLC-8320GPC" described above, the following monodisperse polystyrene having a known molecular weight was used.

(Monodisperse polystyrene)

``A-300'' manufactured by Tosoh Corporation

``A-500'' manufactured by Tosoh Corporation

``A-1000'' manufactured by Tosoh Corporation

``A-2500'' manufactured by Tosoh Corporation

``A-5000'' manufactured by Tosoh Corporation

``F-1'' manufactured by Tosoh Corporation

``F-2'' manufactured by Tosoh Corporation

``F-4'' manufactured by Tosoh Corporation

``F-10'' manufactured by Tosoh Corporation

``F-20'' manufactured by Tosoh Corporation

``F-40'' manufactured by Tosoh Corporation

``F-80'' manufactured by Tosoh Corporation

``F-128'' manufactured by Tosoh Corporation

``F-288'' manufactured by Tosoh Corporation

In addition, the acid value of the ester resin of the present invention is preferably 5 or less, and more preferably 1 or less from the viewpoint of more favorable compatibility with the resin for optical materials.

The ester resin of the present invention is, for example, by subjecting the above-described raw materials to an esterification reaction in the presence of an esterification catalyst, if necessary, within a temperature range of 180 to 250°C for 10 to 25 hours. Can be manufactured. In addition, conditions such as temperature and time of the esterification reaction are not particularly limited, and may be appropriately set. For monocarboxylic acids and dicarboxylic acids, the acid may be used as a raw material, or esterified products, acid chlorides, anhydrides of dicarboxylic acids, and the like may be used as raw materials.

Examples of the esterification catalyst include titanium catalysts such as tetraisopropyl titanate and tetrabutyl titanate; Tin catalysts such as dibutyl tin oxide; and organic sulfonic acid catalysts such as p-toluenesulfonic acid.

The amount of the esterification catalyst used may be appropriately set, but it is generally preferable to use in the range of 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the raw material.

The properties of the ester resin of the present invention differ from each other depending on factors such as the number average molecular weight and the combination of raw materials, but are usually liquid, solid, paste, or the like at room temperature.

As a more specific method for producing an ester resin, a method of reacting the above-described alkylene glycol, oxyalkylene glycol or aryl glycol with a compound having a hydroxyl group at the terminal obtained by using a dicarboxylic acid and a monocarboxylic acid is mentioned. Here, the alkylene glycol, oxyalkylene glycol or aryl glycol, dicarboxylic acid and monocarboxylic acid may be collectively added to the reaction system to react them, or alkylene glycol, oxyalkylene glycol or aryl glycol and di After obtaining a compound having a hydroxyl group at the terminal obtained by using a carboxylic acid, it may be a sequential reaction in which a monocarboxylic acid is further introduced into the reaction system.

In the present invention, the ester resin described above may be used alone and added to a resin for optical materials such as a cellulose ester resin described later, or the following general formula (II)

B ² -G ² -B ² (Ⅱ)

[In formula (II), B ² is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, and a plurality of B ² may be the same or different. 〕

You may use together the diester compound represented by.

^{B 2} in the general formula (II) is a monocarboxylic acid residue, and specifically, an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue is mentioned. Here, the "carboxylic acid residue" represents a group other than -OH in the carboxyl group. As the aryl monocarboxylic acid residue, what is an aryl monocarboxylic acid residue having 6 to 12 carbon atoms, the availability of raw materials and the ease of esterification reaction, and when mixed with a cellulose ester resin described later, have moisture permeability, elastic modulus, and dimensional stability. It is preferable from the viewpoint of easy balance, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, cumic acid, para-butylbenzoic acid, orthotoluic acid, and metatoluic acid. , Paratoluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid, and the like, and may be used alone or in combination of two or more. In particular, from the viewpoint of more easily expressing the effects of the present invention, it is preferably a residue of benzoic acid, paratoluic acid, or dimethylbenzoic acid, and more preferably a residue of benzoic acid or paratoluic acid. In addition, the number of carbon atoms here does not include carbon atoms in the carboxyl group. Moreover, residues, such as nicotinic acid and furoic acid, which may have a substituent or have aromaticity may be used.

As the aliphatic monocarboxylic acid residues, those which are aliphatic monocarboxylic acid residues having 1 to 8 carbon atoms are easy to receive raw materials, ease of esterification reaction, and balance of moisture permeability, elastic modulus, and dimensional stability when mixed with a cellulose ester resin described later. It is preferable from the viewpoint of being easy to catch, and examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, and octylic acid, and may be used alone or in combination of two or more. It is desirable. In addition, the number of carbon atoms here does not include carbon atoms in the carboxyl group.

^{G 2} in the general formula (II) is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue. The glycol residue represents a group after removing a hydrogen atom from a hydroxyl group.

The alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, ethylene glycol, 1,2-propylene glycol, 1 ,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3- And residues such as hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, and may be used alone or in combination of two or more. You may have bottle oil. Among these, from the viewpoint of improving the strength of the film, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propane It is preferably a diol or a residue of 1,5-pentanediol.

The oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, diethylene glycol, triethylene glycol, tetra Residues such as ethylene glycol, dipropylene glycol, and tripropylene glycol may be mentioned, and may be used alone or in combination of two or more.

The aryl glycol residue is preferably an aryl glycol residue having 6 to 18 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, alkylene oxides of hydroquinone, resorcin, bisphenol A, and bisphenol A. Residues such as an adduct, bisphenol F, an alkylene oxide adduct of bisphenol F, a biphenol, and an alkylene oxide adduct of biphenol may be mentioned, and may be used alone or in combination of two or more.

From the viewpoint of further expressing the effect of the present invention, in the general formula (II), B ² is benzoic acid, a residue of paratoluic acid, G ² is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol , 2-methyl-1,3-propanediol, diethylene glycol, and dipropylene glycol residues are preferred.

The said diester compound (II) may be synthesized or commercially available. When synthesizing, the reaction conditions (catalyst, temperature, time, etc.) are, for example, the ester resin used in the present invention ( The conditions used in the synthesis of I) can be used.

The ester resin mixture of the present invention contains the ester resin (I) and the diester compound (II) in the range of 100/0 to 50/50 in terms of mass ratio [ester resin/diester compound], which will be described later. It is preferable because it can be suitably used as a semi-plasticizer for optical resins.

When the diester compound (II) is included, it is suitably disposed between the gaps of the resin for an optical material, particularly a cellulose ester resin, and as a result, the effect of improving moisture permeability, elastic modulus, and dimensional stability is further expressed. , Compatibility with the resin for optical materials can be ensured, and transparency that can be used as an optical film can be more effectively maintained.

The ester resin (I) and the diester compound (II) are further exhibited these effects, and from the viewpoint of suppressing contamination of production lines due to volatilization, and facilitating maintenance of transparency of the optical film. The proportion of the ester resin (I) in the total mass of is preferably 50 to 100% by mass, more preferably 60 to 95% by mass, and most preferably 65 to 90% by mass.

The ester resin mixture of the present invention may be composed of only the ester resin (I) and the diester compound (II), and contains polyester other than the ester resin (I) or diester compound other than the diester compound (II). You can do it. Further, other than ester resin (I) and diester compound (II) may contain what is known as a modifier for so-called optical resins, and the taste of raw materials used in the production of ester resin (I) and diester compound (II) It may contain a reactant.

The ester resin or ester resin mixture of the present invention obtained by such a method or the like can be made to have an excellent balance of elastic modulus, heat resistance, and dimensional stability of the obtained film by blending it with a resin for an optical material, and can be used as a so-called semi-plasticizer. It is possible, and the film obtained is particularly suitable as an optical film.

The resin for an optical material is not particularly limited as long as it has high transparency and can be processed into a film. For example, (meth)acrylic resin, cyclic olefin resin, polycarbonate resin, cellulose ester resin And the like. In particular, it is preferable to use a cellulose ester resin from a viewpoint which the effect of this invention further appears.

The blending amount of the ester resin and the ester resin mixture of the present invention with respect to the optical material resin may be determined according to the desired performance (elastic modulus, heat resistance, etc.). For example, 0.1 to 100 parts by mass of the optical material resin It is a range of 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 3 to 20 parts by mass.

As said cellulose ester resin, some or all of the hydroxyl groups which cellulose obtained from cotton linter, wood pulp, kenaf, etc. are esterified, etc. can be illustrated, for example.

Examples of the cellulose ester resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose nitrate, and the like. When used as a protective film for polarizing plates, cellulose acetate is used. This is preferable because a film excellent in mechanical properties and transparency can be obtained. These cellulose ester resins may be used alone or in combination of two or more.

As the cellulose acetate, the degree of polymerization is preferably in the range of 250 to 400, the degree of acetization is preferably in the range of 54.0 to 62.5% by mass, and more preferably in the range of 58.0 to 62.5% by mass. If the degree of polymerization and acetylation of the cellulose acetate is within this range, a film having excellent mechanical properties can be obtained. In the present invention, it is more preferable to use a so-called cellulose triacetate. In addition, the degree of acetation in the present invention is a mass ratio of acetic acid produced by saponifying the cellulose acetate to the total amount of cellulose acetate.

The number average molecular weight of the cellulose acetate is preferably in the range of 70,000 to 300,000, and more preferably in the range of 80,000 to 200,000. When the number average molecular weight of the cellulose acetate is within this range, a film having excellent mechanical properties can be easily obtained.

The optical film in the present invention uses a resin composition containing a resin for an optical material such as an ester resin or an ester resin mixture of the present invention and a cellulose ester resin, and contains other various additives as necessary. You may use a resin composition.

In order to obtain the optical film of the present invention, methods such as extrusion molding and cast molding are used, for example. Specifically, an unstretched optical film can be extruded using, for example, an extruder equipped with a T-die, a circular die, or the like. When obtaining the optical film of the present invention by extrusion molding, a resin composition obtained by melt-kneading the resin for optical materials such as the ester resin, ester resin mixture, and cellulose ester resin, and other additives in advance is used. Alternatively, it may be melt-kneaded at the time of extrusion molding, and extrusion molding as it is.

Examples of the additives include ester resins of the present invention, modifiers other than diester compounds, thermoplastic resins, ultraviolet absorbers, mat agents, stabilizers, deterioration inhibitors (e.g., antioxidants, peroxide decomposition agents, radical inhibitors). Agents, metal inactivators, acid trapping agents, etc.), and dyes.

Examples of the other modifiers include ester resins other than ester resins and diester compounds specified in the present invention, phosphoric acid esters such as triphenyl phosphate (TPP), tricresyl phosphate and cresyl diphenyl phosphate, dimethyl phthalate, and diethyl phthalate. , Phthalic esters such as dibutylphthalate and di-2-ethylhexylphthalate, ethylphthalylethylglycolate, butylphthalylbutylglycolate, trimethylolpropane tribenzoate, pentaerythritol tetraacetate, tributyl acetyl citrate, etc. , It can be used within a range that does not impair the effects of the present invention.

Although it does not specifically limit as said thermoplastic resin, For example, polyester resin other than the ester resin of this invention, polyester ether resin, polyurethane resin, acrylic resin, epoxy resin, toluene sulfonamide resin, etc. are mentioned.

Although it does not specifically limit as said ultraviolet absorber, For example, an oxybenzophenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone compound, a cyanoacrylate type compound, a nickel complex salt type compound, etc. are mentioned. . It is preferable to use the said ultraviolet absorber in the range of 0.01-2 mass parts with respect to 100 mass parts of said cellulose ester resins.

Examples of the mat agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin, talc, and the like. It is preferable to use the said mat agent in the range of 0.1-0.3 mass parts with respect to 100 mass parts of said cellulose ester resins.

Examples of the stabilizer include calcium hydroxide, calcium carbonate, and fatty acid metal salts. It is preferable to use the said stabilizer in the range of 50-5000 ppm with respect to 100 mass parts of said cellulose ester resins.

The dye is not particularly limited as long as it is a range that does not impair the object of the present invention.

In addition, in addition to the above molding method, the optical film is formed by casting a resin solution obtained by dissolving a resin for an optical material such as the cellulose ester resin composition in an organic solvent on a metal support, and then, the organic solvent. It can also be obtained by forming by a so-called solution casting method (solvent casting method) in which distillation is removed and dried.

According to the solution casting method, since the orientation of the resin for optical materials such as the cellulose ester resin in the film during molding can be suppressed, the resulting film can exhibit substantially optical isotropy. The film exhibiting optical isotropy can be used, for example, for an optical material such as a liquid crystal display, and is particularly useful for a protective film for polarizing plates. Further, the film obtained by the above method is difficult to form irregularities on its surface, and is excellent in surface smoothness.

The solution casting method generally includes a first step of dissolving the resin composition in an organic solvent and casting the obtained resin solution onto a metal support, and distilling off and drying the organic solvent contained in the cast resin solution. It consists of a 2nd process of forming a film, and a 3rd process of peeling and heat-drying the film formed on the metal support following it from the metal support.

As the metal support used in the first step, an endless belt-like or drum-like metal can be exemplified, and for example, a stainless steel and a mirror-finished surface can be used. have.

When casting a resin solution on the metal support, it is preferable to use a resin solution filtered through a filter in order to prevent foreign matters from being mixed in the resulting film.

The drying method of the second step is not particularly limited, for example, by hitting the upper and/or lower surfaces of the metal support with wind in a temperature range of 30 to 50° C., A method of evaporating 50 to 80% by mass to form a film on the metal support is exemplified.

Next, the third step is a step of peeling the film formed in the second step from the metal support and drying by heating under a temperature condition higher than that of the second step. As the heat drying method, for example, a method of increasing the temperature step by step under a temperature condition of 100 to 160°C is preferable because good dimensional stability can be obtained. By heating and drying under the above temperature conditions, the organic solvent remaining in the film after the second step can be almost completely removed.

In addition, in the first to third steps, the organic solvent may be recovered and reused.

The organic solvent that can be used when mixing and dissolving the resin composition in an organic solvent is not particularly limited as long as it is capable of dissolving them. For example, when cellulose acetate is used as a resin for an optical material, a good solvent As for example, it is preferable to use organic halogen compounds, such as methylene chloride, and dioxolanes.

In addition, the combination of a poor solvent such as methanol, ethanol, 2-propanol, n-butanol, cyclohexane, and cyclohexanone together with the good solvent is used to improve the production efficiency of the film. desirable.

The mixing ratio of the good solvent and the poor solvent is preferably in the range of the good solvent/poor solvent = 75/25 to 95/5 mass ratio.

The concentration of the resin for optical materials in the resin solution is preferably 10 to 50% by mass, more preferably 15 to 35% by mass.

In the present invention, for example, the optical film obtained by stretching the optical film in the unstretched state obtained by the above-described method is stretched longitudinally and uniaxially in the mechanical flow direction and uniaxially stretched horizontally in a direction orthogonal to the mechanical flow direction, if necessary. You can get it. Further, a biaxially stretched stretched film can be obtained by stretching by a sequential biaxial stretching method of roll stretching and tenter stretching, a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, or the like. The draw ratio is preferably 0.1% or more and 300% or less in at least one direction, more preferably 0.2% or more and 250% or less, and most preferably 0.3% or more and 200% or less. By designing in this range, a stretched optical film preferable from the viewpoints of birefringence, heat resistance, and strength is obtained.

Since the optical film of the present invention is excellent in elastic modulus, heat resistance, moisture permeability, and dimensional stability, it can be used, for example, in an optical film of a liquid crystal display device. As the optical film of the liquid crystal display device, for example, a protective film for a polarizing plate, a retardation film, a reflective film, a viewing angle improving film, an anti-glare film, an anti-reflective film, an antistatic film, a color filter, etc., among them, a polarizing plate It can be preferably used as a protective film for use.

The film thickness of the optical film is preferably in the range of 20 to 120 µm, more preferably in the range of 25 to 100 µm, and particularly preferably in the range of 25 to 80 µm. In the case of using the optical film as a protective film for a polarizing plate, if the film thickness is in the range of 25 to 80 µm, it is suitable for thinning of the liquid crystal display device, and has excellent film strength, Rth stability, moisture permeability, etc. Can maintain performance.

The optical film of the present invention is characterized in that the modulus of elasticity is higher than that in the case where an ester resin is not blended. In general, with respect to cellulose ester resin, the polyester resin blended with the aim of enhancing its processability is sometimes called a ``plasticizer,'' but the ester resin of the present invention can improve the strength of the resin for optical materials rather than the plasticizing effect. From the point of view, it is used as a semi-plasticizer, which has a performance different from that of the prior art.

In addition, since the protective film for polarizing plates does not generate bleed under high temperature and high humidity, and can be adjusted to a desired phase difference, it can be widely used in various liquid crystal display systems depending on the application.

Examples of the liquid crystal display system include IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), OCB (Optically Compensation). Bend: Optically Compensatory Bend) and the like can be exemplified.

The optical film according to the present invention, as an optical material, is a polarizing plate protective film used in displays such as a liquid crystal display device, a plasma display, an organic EL display, a field emission display, and a rear projection television, a 1/4 wavelength plate, and a 1/2 It can be suitably used for a wave plate, a viewing angle control film, a retardation film such as a liquid crystal optical compensation film, and a display front plate. In addition, the resin composition of the present invention can also be used for waveguides, lenses, optical fibers, substrates for optical fibers, coating materials, lenses for LEDs, lens covers, etc. in the fields of optical communication systems, optical exchange systems, and optical measurement systems. have.

(Example)

Hereinafter, the present invention will be described in more detail based on examples. Parts and percentages in the examples are based on mass unless otherwise limited.

Synthesis Example 1

In a 1 liter 4 necked flask, 337 g of 1,2-propylene glycol (hereinafter abbreviated as ``PG'') as a glycol component, 376 g of isophthalic acid (hereinafter abbreviated as ``IPA'') as a dicarboxylic acid component, and adipic acid (hereinafter `` (Abbreviated as "AA") 111 g and 0.05 g of tetraisopropyl titanate (hereinafter abbreviated as "TIPT") as a catalyst were added, and the temperature was raised to 230°C step by step from a nitrogen introduction pipe under a nitrogen stream. When the condensation reaction was carried out at 230° C. for 8 hours and the acid value became 1.0 or less, the reaction product was filtered and taken out to obtain an ester resin (1). The obtained ester resin (1) was a pale yellow liquid at room temperature, had an acid value of 0.28, a hydroxyl value of 190, a number average molecular weight of 720, and a residual PG amount of 3.1% by mass. Further, 660 g of ester resin (1) and 137 g of acetic anhydride were added to a 1-liter three-necked flask, and reacted at 120°C for 2 hours from a nitrogen inlet tube under a nitrogen stream. After the reaction, excess acetic anhydride and acetic acid were distilled off under reduced pressure to obtain an ester resin (1'). Ester resin (1') was a pale yellow liquid at room temperature, had an acid value of 0.58, a hydroxyl value of 0.0, a number average molecular weight of 790, and a residual PG amount of 0 mass%.

Synthesis Example 2

In a 1 liter 4 necked flask, 352 g of PG as a glycol component, 257 g of IPA, 226 g of AA, and 0.05 g of TIPT as a catalyst were added as a glycol component, and the temperature was raised to 230°C stepwise from a nitrogen inlet tube under a nitrogen stream. When the condensation reaction was carried out at 230° C. for 8 hours and the acid value became 1.0 or less, the reaction product was filtered and taken out to obtain an ester resin (2). Further, 660 g of the obtained ester resin (2) and 133 g of acetic anhydride were put into a 1-liter 3-neck flask, and the mixture was reacted at 120° C. for 2 hours from a nitrogen introduction tube under a nitrogen stream. After the reaction, excess acetic anhydride and acetic acid were distilled off under reduced pressure to obtain an ester resin (2'). The ester resin (2') was a pale yellow liquid at room temperature, had an acid value of 0.57, a hydroxyl value of 0.0, a number average molecular weight of 780, and a residual PG amount of 0 mass%.

Synthesis Example 3

In a 3-liter four-neck flask, 922 g of PG as a glycol component, 944 g of phthalic anhydride (hereinafter abbreviated as ``PA'') as a dicarboxylic acid component, 310 g of AA, and 0.13 g of TIPT as a catalyst were added, , The temperature was raised to 220°C step by step. When the condensation reaction was carried out at 220° C. for 8 hours, and the acid value became 1 or less, the reaction product was filtered and taken out to obtain an ester resin (3). The obtained ester resin (3) was a pale yellow liquid at room temperature, had an acid value of 0.50, a hydroxyl value of 163, a number average molecular weight of 790, and a residual PG amount of 3.0% by mass. Moreover, the ester resin (3') was obtained by removing excess glycol at 150 degreeC under reduced pressure of the ester resin (3). The obtained ester resin (3') was a pale yellow liquid at room temperature, had an acid value of 0.18, a hydroxyl value of 147, a number average molecular weight of 800, and a residual PG amount of 0.5% by mass.

Examples 1 to 2, Comparative Examples 1 to 2

<Adjustment of cellulose ester optical film>

Triacetylcellulose resin ("LT-35" manufactured by Daicel) 100 parts, ester resin (1') to (2'), ester resin (1), (3) 10 parts, methylene chloride 810 parts and methanol 90 It added to the mixed solvent which consists of part, and dissolved, and the dope liquid which is a cellulose ester resin composition was prepared. These dope liquids were cast on a glass plate, dried at room temperature for 16 hours, and then further dried at 50°C for 30 minutes and 120°C for 30 minutes to obtain an optical film (film thickness of 60 μm or 40 μm). With respect to the obtained film, physical properties were measured according to the following, and the results are shown in Table 1.

<Measurement of elastic modulus of optical film>

Equipment: Autograph AG-IS manufactured by Shimadzu Seisakujo Co., Ltd.

Test piece: 150mm×10mm, 40㎛-thick strip type

Chuck spacing: 100㎜

Test speed: 10㎜/min

The larger the elastic modulus, the harder the film is.

<Evaluation method of modulus of elasticity>

×: modulus of elasticity is 4600 MPa or less

○: Elasticity modulus is higher than 4600 MPa, 4700 MPa or less

◎: Elastic modulus is higher than 4700 MPa

<Measurement of heat resistance of optical film>

Equipment: RSA-III tension mode manufactured by TA Instruments

Heating rate: 3℃/min

Frequency: 1Hz

Load strain: 0.1%

Film thickness of test piece: 60㎛

The peak top of tan δ is taken as Tg, and the higher the Tg, the better the heat resistance.

<heat resistance evaluation method>

×: Tg is 180°C or less

○: Tg is higher than 180℃

<Measurement of dimensional stability of optical film>

Equipment: SIINT TMA/SS6100+humidity control unit made by Hitachi Hi-Tech

Measurement temperature: 40℃ constant

Relative humidity: 0% to 80%

Measurement load: 50mN

Film thickness of test piece: 60㎛

The rate of dimensional change was measured when the relative humidity was 0% to 80%. The smaller the rate of change, the better the dimensional stability.

<Method of evaluating dimensional stability>

×: dimensional change rate is greater than 0.43%

○: Dimensional change rate is 0.40% or more, 0.43% or less

◎: Dimensional change rate is less than 0.40%

<HAZE>

The HAZE value was measured in accordance with JIS K 7105 using a turbidimeter ("NDH 5000" manufactured by Nihon Denshoku Kogyo Co., Ltd.). The closer the obtained value is to 0%, the more transparent it is.

<Method of evaluating transparency>

×: HAZE value is greater than 1.0%

○: HAZE value is less than 1.0%

<Measurement of moisture permeability of optical film>

It measured according to the method described in JIS Z 0208. Measurement conditions were performed at a temperature of 40°C and a relative humidity of 90%. The smaller the value obtained, the better the moisture permeability resistance.

<Evaluation method of moisture permeability>

×: moisture permeability of 600g/m²·24h or more

○: moisture permeability is less than 600g/㎡·24h

[Table 1]

By using isophthalic acid as the dicarboxylic acid component of the ester resin (I), the elastic modulus and Tg were improved. Further, by sealing the terminal of the ester resin (I) with a monocarboxylic acid, the moisture absorption dimensional change was suppressed, and the moisture permeability resistance was also improved.

Synthesis Example 4

In a 3-liter four-neck flask, 1,906 g of paratoluic acid as a monocarboxylic acid component, 639 g of PG as a glycol component, and 0.153 g of TiPT as a catalyst were added, and then the temperature was raised to 220°C and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After that, the reduced pressure was released and the temperature was lowered, and the reaction product was filtered and taken out to obtain a transparent yellow liquid diester compound (a). The number average molecular weight (Mn) of the diester compound (a) was 310, the acid value was 0.10, and the hydroxyl value was 4.

Synthesis Example 5

In a 2-liter 4-neck flask, 900 g of benzoic acid (hereinafter abbreviated as “BzA”) as a monocarboxylic acid component, 294 g of PG as a glycol component, 50 g of dipropylene glycol, and 0.62 g of TiPT as a catalyst were added, and the temperature was raised to 220°C. It was allowed to react for time. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After the outflow of unreacted alcohol disappeared, the reduced pressure was released to lower the temperature, and the reaction product was filtered out to obtain a diester compound (b) in a transparent yellow liquid state. The number average molecular weight (Mn) of the diester compound (b) was 300, the acid value was 0.07, and the hydroxyl value was 7.

Synthesis Example 6

In a 2-liter four-neck flask, 952 g of BzA as a monocarboxylic acid component, 124 g of PG as a glycol component, 281 g of diethylene glycol, and 0.68 g of TiPT as a catalyst were added, and then the temperature was raised to 220°C and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After the distillation of the unreacted alcohol disappeared, the pressure was released and the temperature was lowered, and the reaction product was filtered and taken out to obtain a diester compound (c) in a transparent yellow liquid state. The number average molecular weight (Mn) of the diester compound (c) was 350, the acid value was 0.05, and the hydroxyl value was 3.

Examples 3 to 7, Comparative Example 3

<Adjustment of cellulose ester optical film>

100 parts of triacetyl cellulose resin ("LT-35" manufactured by Daicel), ester resin (1'), ester resin (3') and diester compounds (a) to (c) in the ratio shown in Table 2 According to this, it was added to a mixed solvent comprising 10 parts, methylene chloride 810 parts, and methanol 90 parts, and dissolved to prepare a dope solution as a cellulose ester resin composition. These dope liquids were cast on a glass plate, dried at room temperature for 16 hours, and then further dried at 50°C for 30 minutes and 120°C for 30 minutes to obtain an optical film (film thickness of 60 μm or 40 μm). With respect to the obtained film, physical properties were measured according to the above, and the results are shown in Table 2.

[Table 2]

By the addition of the diester compound (II), the elastic modulus, dimensional stability, and moisture permeability resistance were significantly improved. All have a low HAZE value and have sufficient transparency as an optical film.

Claims (14)

The following general formula (I)
B ¹ -(G ¹ -A) _n -G ¹ -B ¹ (I)
[In formula (1), B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A This isophthalic acid residue, n is the number of repetitions, and G ¹ and A may be the same or different for ^{each repetition, and a plurality of B 1} and G ¹ may be the same or different]
Ester resin, characterized in that represented by. The method of claim 1,
^{B 1} in the general formula (1) is an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms, G ¹ is an alkylene glycol residue having 2 to 12 carbon atoms, and an oxyalkylene glycol having 4 to 12 carbon atoms Ester resin, which is a residue or an aryl glycol residue having 6 to 18 carbon atoms, and the average value of n is 1.0 to 10.0. The method according to claim 1 or 2,
The ester resin in which the number average molecular weight of the ester resin is in the range of 350 to 2000. The method according to any one of claims 1 to 3,
In the general formula (1), B ¹ is a residue of acetic acid, and G ¹ is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, and 2-methyl-1,3-propane. Is one or more residues selected from the group consisting of diols, A is one or more residues selected from the group consisting of succinic acid, adipic acid, dicarboxycyclohexane, phthalic acid, terephthalic acid and isophthalic acid, and the total number of moles of A Ester resin in which 25 mol% or more is an isophthalic acid residue. The method according to any one of claims 1 to 4,
An ester resin wherein 40 to 100 mol% of the total number of moles of A in the general formula (I) is an isophthalic acid residue. The method according to any one of claims 1 to 5,
An ester resin in which the amount of residual glycol in the ester resin is 1.5% by mass or less. The ester resin according to any one of claims 1 to 6 and the following general formula (II)
B ² -G ² -B ² (Ⅱ)
[In formula (II), B ² is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, and a plurality of B ² may be the same or different. 〕
An ester resin mixture comprising a diester compound represented by. The method of claim 7,
The diester compound is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol or dipropylene glycol, and benzoic acid or paratoluic acid A mixture of ester resins that are diesters. The method according to claim 7 or 8,
An ester resin mixture containing the ester resin and the diester compound in a mass ratio [ester resin/diester compound] in the range of 95/5 to 50/50. A semi-plasticizer for a resin for optical materials, comprising the ester resin according to any one of claims 1 to 6 or the ester resin mixture according to any one of claims 7 to 9. A cellulose ester resin composition comprising the semi-plasticizer according to claim 10 and a cellulose ester resin, and comprising 1 to 30 parts by mass of the semi-plasticizer with respect to 100 parts by mass of the cellulose ester resin. . An optical film containing the cellulose ester resin composition according to claim 11. The method of claim 12,
Optical film for polarizing plate protection. A liquid crystal display device comprising the optical film according to claim 12 or 13.