WO2009110337A1

WO2009110337A1 - Polyester resin for thermoformed optical film and biaxially oriented polyester film obtained from the same

Info

Publication number: WO2009110337A1
Application number: PCT/JP2009/053141
Authority: WO
Inventors: 浩一旦; 純坂本; 宏光高橋; 弘造高橋; 大輔尾形
Original assignee: 東レ株式会社
Priority date: 2008-03-05
Filing date: 2009-02-23
Publication date: 2009-09-11
Also published as: CN101959941B; KR20100138993A; CN101959941A; TW200951163A; KR101553729B1; JPWO2009110337A1

Abstract

A polyester resin composition characterized by having a glass transition temperature (Tg) of 83°C or higher and a melting point (Tm) of 230°C or lower and having controlled crystallizability. This polyester has excellent surface thermoformability. In particular, the surface of the polyester can be formed into various shapes, e.g., a shape having ultrahigh fineness or a high aspect ratio. The polyester is for use as a thermoformed optical film excellent in heat resistance and transparency.

Description

Polyester resin for heat-shaped optical film and biaxially oriented polyester film using the same

The present invention relates to a heat-forming optical film polyester that can be formed into a wide variety of shapes such as heat-formability on the surface, particularly ultra-high definition and high aspect ratio, and has excellent heat resistance and transparency. .

Optical elements have long been made of glass with excellent transparency and low birefringence. However, since it is inferior in moldability and difficult to reduce in weight, recently, polymer materials with excellent moldability, light weight, and easy property control have been used for disc substrates, lenses, cables, various display films, etc. according to their characteristics. Yes.

On the other hand, in recent years, the importance of a technique for forming a surface fine structure is increasing mainly in the optical field. Photolithography is a typical technique for microfabrication. However, if the exposure wavelength is shortened to control the fine dimensions with high accuracy, the initial cost of the exposure machine itself and the cost of the mask to be used are increased. Since the irradiation spot diameter is small, the productivity is low for forming a fine structure with a large area.

Thus, recently, imprint lithography has been proposed by Chou et al. As a technique for easily shaping a fine structure (see Non-Patent Document 1). Imprint lithography is a technique for transferring a pattern on a mold to a resin, and there are two types of methods, thermal and optical. The thermal type is a method in which a thermoplastic resin is heated to a glass transition temperature (Tg) or higher and lower than the melting point (Tm), and a mold having a concavo-convex pattern is pressed thereon, and the optical type is a photocurable property. In this technique, the pattern on the mold is transferred to the resin by irradiating and curing the light with the mold pressed against the resin. Compared to the optical method, the thermal method has a feature that it is easier to shape a shape with a higher aspect ratio. Although these technologies require initial costs for mold fabrication, many microstructures can be replicated from a single mold, resulting in a technology that allows the microstructure to be shaped cheaply compared to photolithography. It is.

Therefore, in recent years, using this imprint lithography, development of plastic elements in various fields such as flat panel display members such as liquid crystal display devices (Patent Document 1), optical waveguides used for optical communication (Patent Document 2), etc. Is underway.

Among these, polycarbonate (PC) and polymethyl methacrylate (hereinafter, PMMA) are polymer materials studied for thermal imprint lithography with a high degree of freedom in shape. However, although PC is excellent in heat resistance, it has poor shapeability, it is difficult to form a high-definition pattern, and optical distortion remains after molding. On the other hand, PMMA has an example in which a high-definition and high-aspect ratio structure can be formed by lowering the molecular weight, but the mechanical strength is poor and the sheet is fragile and unsuitable for practical use.

Polyester is promising because of its excellent cost, mechanical strength, and melt film-forming properties. Polyethylene terephthalate (PET) is crystalline, so it has a high Tm, poor formability, and is not suitable for shaping. It is necessary to increase the mold temperature. Mold heating, 2. 2. imprint shaping; 3. mold cooling; There is a problem that the cycle time required for mold peeling is long and the productivity is low, and the heat resistance is low due to the low Tg.
JP 2006-152074 A JP-A-7-188401 S. Y. Chou et al., "Appl. Phys. Lett.", American Physical Society, 1995, Vol. 67, No. 21, p. 3314

The present invention solves the above-mentioned problems of the prior art, and can be shaped into a wide variety of shapes such as heat-formability on the surface, especially ultra-high definition and high aspect ratio, and heat-shaping productivity. Another object of the present invention is to provide a polyester resin for heat-shaped optical film having excellent heat resistance and transparency.

In order to solve the above problems, the present invention has the following features.
(1) A polyester resin for a heat-shaped optical film having a glass transition temperature (Tg) of 83 ° C. or higher, a melting point (Tm) of 230 ° C. or lower, and a crystal melting heat (ΔHm) of 0.3 J / g or higher.
(2) Thermal shaping according to (1), characterized in that the temperature difference (ΔTcg: Tcc-Tg) between the temperature rising crystallization temperature (Tcc) and the glass transition point (Tg) is 50 to 90 ° C. Polyester resin for optical film.
(3) The heat-shaped optical film according to (1) or (2), wherein the polyester is a copolymer comprising a terephthalic acid residue, a 2,6-naphthalenedicarboxylic acid residue, and an ethylene glycol residue. Polyester resin.
(4) The polyester resin for heat-shaped optical film as described in any one of (1) to (3), wherein the 2,6-naphthalenedicarboxylic acid residue is 8 to 17 mol%.
(5) The polyester resin for heat-shaped optical film as described in any one of (1) to (4), which contains a crystal nucleating agent.
(6) The polyester resin for heat-shaped optical film as described in (5), wherein the number average average diameter of the crystal nucleating agent or crystal nucleating agent derivative particles in the resin is 1.2 μm or less.
(7) The polyester resin for heat-shaped optical film as described in any one of (5) to (6), wherein the crystal nucleating agent is an organic carboxylic acid sodium salt.
(8) The polyester resin for heat-shaped optical film as described in (7), wherein the sodium element content is 50 to 1500 ppm with respect to the whole polyester resin.
(9) The polyester resin for heat-shaped optical film as described in any one of (5) to (6), wherein the crystal nucleating agent is talc.
(10) 2 g of polyester resin was dissolved in 20 ml of phenol / 1,1,2,2, tetrachloroethane 3/2 (volume ratio) mixed solvent, and the haze of the solution measured using a cell having an optical path length of 20 mm was 40%. The polyester resin for heat-shaped optical film as described in any one of (1) to (9), which is as follows.
(11) The polyester resin for heat-shaped optical film as described in any one of (1) to (10), wherein IV (intrinsic viscosity) is 0.55 or more and 0.75 or less.
(12) A layer composed of the polyester resin according to any one of (1) to (11), wherein the layer composed of the polyester resin is laminated on at least one outermost layer in an amount of 1 to 30 μm and has a plane orientation coefficient of 0.12 or less. A biaxially oriented polyester film.
(13) Biaxially having a prism-shaped layer made of the polyester resin, wherein the heat-forming layer made of the polyester resin according to any one of (1) to (11) is laminated on at least one outermost layer of 1 to 30 μm. Oriented polyester film.

According to the present invention, there is provided a polyester resin for a heat-shaped optical film which is excellent in heat-shaping property and has excellent heat-shaping productivity, heat resistance and transparency. By using this, it can be used for applications that require both heat-shaping productivity and heat resistance, such as a prism sheet for a backlight used in various display members.

The figure which shows the relationship between the acid component of terephthalic acid, naphthalene dicarboxylic acid, and ethylene glycol copolymer polyester, and Tg and Tm. The schematic diagram of the metal mold | die for heat shaping, and a forming sheet. Here, (a) is a schematic view of the cross section of the shaping portion of the mold, (b) is a schematic view of the shaping portion of the mold as viewed from diagonally above, and (c) is shaped by the mold. It is the figure which showed the film cross section typically. The figure which shows typically the structure which incorporated the prism sheet using resin of this invention in the backlight. The figure which shows typically the heat shaping flow of a present Example. Here, (1) schematically represents a mold heating step, (2) schematically represents a heat shaping / mold cooling step, and (3) schematically represents a film release step.

Explanation of symbols

a: Prism sheet using the polyester resin of the present invention b: Diffusion sheet
c: Diffuser plate d: Reflective sheet
e: fluorescent lamp f: heating / cooling plate g: mold h: film

The present invention will be described in detail below.

The present invention solves the above problems, that is, the problems of conventional resins, and after intensive studies, a specific polyester resin whose composition is controlled to have specific physical properties solves the above problems all at once, and heat shaping The inventors have found that a sheet having excellent properties, heat shaping productivity, heat resistance, and transparency can be formed, and have reached the present invention.

That is, the polyester resin of the present invention has a glass transition temperature (Tg) of 83 ° C. or higher, a melting point (Tm) of 230 ° C. or lower, and a crystal melting heat (ΔHm) of 0.3 J / g or higher.

From the viewpoint of formability, the resin to be heat-shaped is preferably uniform and low in crystallinity without stretch distortion or the like before heat-forming, and has high Tg and does not hinder transparency after forming. Crystallization within a range is preferable from the viewpoint of the thermal stability of the shaped shape. Only by raising the glass transition temperature, the thermal stability after shaping is not sufficient, and excellent thermal stability is realized by combining with crystallization. On the other hand, if the glass transition temperature is too high, the heat shaping property is remarkably lowered.

In order to achieve both the amorphousness before shaping and the transparency after shaping, that is, the microcrystalline structure, the resin must be crystalline, and before shaping, the resin is near the melting point of the polyester resin of the present invention. It is necessary to remelt the surface layer by heat treatment at the heat treatment temperature and to make it uniform by relaxing the orientation in order to realize excellent formability. In the heat treatment, the lower the melting point of the polyester resin of the present invention is, the easier it is to make it uniform. Further, in order to improve the film forming property, the polyester resin of the present invention having a shaping layer on the surface layer of a base material having a higher melting point (here, the melting point of the resin constituting the base material is Tm1) (here However, in the case of a laminated film, the heat treatment temperature (Ta) is preferably Tm1> Ta> Tm2 from the viewpoint of film forming property and heat treatment effect, When Tm2 is 230 ° C. or lower, stable film-forming is possible even when PET having a melting point of 260 ° C. is selected as the base material, film-forming properties, heat-forming properties, compatibility between layers, and low cost To preferred. In addition to the heat treatment step, it is preferable in terms of formability such as mold followability that the melting point is low at the time of heat shaping.

For this reason, the melting point of the polyester resin of the present invention is preferably 230 ° C. or less, and if it is higher than this, the homogenization and low crystallization during heat treatment will be insufficient, and the heat formability will deteriorate. For example, in the case of lamination with PET, even if the melting point is 260 ° C. or lower, it is not preferable that the melting point is higher than 230 ° C. because stable film formation and heat treatment cannot be achieved in the heat treatment step. A lower limit of the melting point is not particularly provided, but if it is lower than 130 ° C., the glass transition temperature is also lowered, which is not preferable.

Further, the polyester resin of the present invention preferably has Tg ≧ 83 ° C. More preferably, Tg ≧ 85 ° C. By being in this range, for example, in the case of an optical sheet such as a prism sheet used in the field of flat panel displays, the required long-term heat resistance can be greatly improved. When the temperature is lower than this temperature, the shape that is thermally shaped during long-term use changes and the performance deteriorates. There is no particular upper limit, but if it is higher than 150 ° C., the heat formability is lowered, which is not preferable.

Further, the polyester resin of the present invention preferably satisfies ΔHm ≧ 0.3 J / g. More preferably, ΔHm ≧ 1.0 J / g, and further preferably ΔHm ≧ 20.0 J / g. If it is smaller than this, it will not be crystallized at the time of heat shaping, and the thermal stability will decrease. There is no particular upper limit, but if it exceeds 40.0 J / g, it may be crystallized too much during heat shaping, which may result in poor molding.

The polyester resin of the present invention is preferably a homopolymer having a diol component and a dicarboxylic acid component each consisting of one component, and is preferably a copolymerized polyester resin in which either the diol component or the dicarboxylic acid component or both are composed of a plurality of monomers. . In any case, the type of monomer is not particularly limited. Specific monomers and the like will be described later. Among them, those having a terephthalic acid residue such as dimethyl terephthalate (DMT), those having a naphthalenedicarboxylic acid residue such as dimethyl 2,6-naphthalenedicarboxylate (DMN), ethylene glycol The copolyester made of is preferable from the viewpoints of cost and polymerizability.

Regarding the method of controlling the Tg, Tm, and ΔHm of the polyester resin so as to fall within the scope of the present invention, first, Tg and Tm are determined by the copolymer composition of the polyester resin. In order to obtain a high Tg, it is effective to select a cyclic monomer having a rigid structure, and to increase its composition ratio, and in order to reduce the Tm, to select a linear monomer having a flexible structure, It is effective to disturb the ordered structure and reduce the crystallinity by introducing a copolymer component.

As a specific example, an example of dimethyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, and ethylene glycol copolymer is shown in FIG. As shown in the figure, Tg is on the line connecting Tg of homopolymers such as PET and PEN having a single diol component and dicarboxylic acid component, and is a rigid monomer of cyclic monomer of 2,6-naphthalenedicarboxylic acid. The higher the copolymerization ratio, the higher. Tm is higher in the case of a homopolymer than that of a copolymer, and this Tm is determined by the rigidity of the monomer. Tm decreases when a linear monomer having a flexible structure is selected as the monomer, or when the composition departs from a single composition and the regularity of the polymer backbone decreases. Here, if the composition is too far from the homopolymer, Tm disappears and becomes amorphous. In the copolymer system of FIG. 1, Tg is 83 ° C. or higher and Tm is 230 ° C. or lower in the region of about 12 mol% of 2,6-naphthalenedicarboxylic acid.

ΔHm generally decreases as the composition approaches the amorphous region. Therefore, in a region where ΔHm does not satisfy 0.3 J / g or more, it can be controlled to 0.3 J / g or more by adding a crystal nucleating agent or by controlling IV low to facilitate crystallization.

That is, in order to control the Tg, Tm, and ΔHm of the polyester resin within the range of the present invention, a monomer that contributes to a high Tg is selected, the melting point is lowered by copolymerization of other monomers, and the copolymerization ratio is made amorphous. It is effective to select a composition range that does not become necessary, and it is effective to increase ΔHm by adding a crystal nucleating agent as necessary.

In the polyester resin of the present invention, it is also preferable that the temperature difference (ΔTcg: Tcc−Tg) between the temperature rising crystallization temperature (Tcc) and the glass transition point (Tg) is 50 ° C. ≦ ΔTcg ≦ 90 ° C. . More preferably, 60 ° C. ≦ ΔTcg ≦ 90 ° C., and still more preferably 60 ° C. ≦ ΔTcg ≦ 85 ° C. When ΔTcg is larger than this, crystallization at the time of heat shaping does not proceed sufficiently, and the thermal stability is lowered. If ΔTcg is smaller than this, it will crystallize at the time of the heat treatment before the heat shaping, and the heat shaping property is lowered.

The polyester resin of the present invention preferably contains a crystal nucleating agent. By containing a crystal nucleating agent, ΔTcg can be controlled to some extent independent of Tg and Tm of the resin, and various thermal characteristics can be more easily satisfied.

Here, the crystal nucleating agent has the effect of reducing ΔTcg, and the effect can be adjusted by the type and the amount added. Further, since the number of crystal nuclei increases due to the presence of the crystal nucleating agent, the size of the generated crystal becomes small and uniform, and whitening during microcrystallization can be suppressed.

As the crystal nucleating agent, those generally used as polymer crystal nucleating agents can be used without particular limitation, and any of inorganic crystal nucleating agents and organic crystal nucleating agents can be used. Specific examples of inorganic crystal nucleating agents include talc, kaolin, montmorillonite, synthetic mica, clay, zeolite, silica, graphite, carbon black, calcium sulfide, boron nitride, aluminum, zinc oxide, magnesium oxide, titanium oxide, and oxidation. Examples thereof include metal oxides such as aluminum and neodymium oxide, metal carbonates such as calcium carbonate, and metal sulfates such as barium sulfate. These inorganic crystal nucleating agents are preferably modified with an organic substance in order to enhance dispersibility in the composition. Specific examples of the organic crystal nucleating agent include acetic acid, oxalic acid, propionic acid, butyric acid, octanoic acid, stearic acid, montanic acid, benzoic acid, terephthalic acid, lauric acid, myristic acid, toluic acid, salicylic acid, Combination of various organic carboxylic acids such as naphthalenecarboxylic acid and cyclohexanecarboxylic acid, various organic sulfonic acids such as p-toluenesulfonic acid and sulfoisophthalic acid, and various metals such as sodium, potassium, lithium, calcium, magnesium, barium, and aluminum Organic carboxylic acid metal salt, organic sulfonic acid metal salt, stearic acid amide, ethylenebislauric acid amide, palmitic acid amide, hydroxy stearic acid amide, erucic acid amide, trimesic acid tris (t-butylamide) and other organic carboxylic acid amides, Low Polymers such as polyethylene, high density polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, high melting point polylactic acid, ethylene-acrylic Sodium salt of acid or methacrylic acid copolymer, sodium metal salt of styrene-maleic anhydride copolymer, alkali metal salt of polymer having carboxyl group, alkaline earth metal salt (so-called ionomer), benzylidene sorbitol and its derivatives, sodium-2 Phosphorus compound metal salts such as 2,2'-methylenebis (4,6-di-t-butylphenyl) phosphate and 2,2-methylbis (4,6-di-t-butylphenyl) sodium However, it is not limited to these.

As the crystal nucleating agent used in the present invention, among those exemplified above, at least one selected from organic carboxylic acid sodium salt and talc is particularly preferable from the viewpoint of crystallization promoting effect and low haze of the resin. The crystal nucleating agent used in the present invention may be used alone or in combination of two or more.

The blending amount of the crystal nucleating agent is preferably in the range of 0.01 to 30 parts by weight, more preferably in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the polyester resin containing various fillers. The range of 1 to 3 parts by weight is more preferable.

In addition, various thermal characteristic values such as Tm, Tg, Tcc, ΔHm, and heat-up crystallization calorie (ΔHc) of the polyester resin in the present invention are temperature rise curves of differential scanning calorimetry (DSC) of a sample in a substantially amorphous state. It is a value calculated from Specifically, a 2nd cycle after the DSC is melted in the first cycle and then rapidly cooled to an amorphous solid is used. Here, the cooling rate after the 1st cycle melting must be 100 ° C./min or more, and the difference ΔHm−ΔHc between ΔHm and ΔHc of the resin when the temperature rises by 2nd cycle is ΔHm−ΔHc ≦ 5 J / g It must be amorphous. If it is larger than this, crystallization proceeds in the process of cooling the resin, and an accurate value cannot be calculated. In that case, it is necessary to further increase the cooling rate by changing the cooling rate setting, or by taking the sample out of the electric furnace and exposing it to cold air or immersing it in liquid nitrogen in the sample cooling process.

In the case of using an organic carboxylic acid sodium salt, the sodium element is more preferably in the range of 50 to 1500 ppm, more preferably 150 to 1000 ppm with respect to the polyester resin. When it is larger than this range, the haze of the resin is increased, which is not suitable for optical applications. On the other hand, if it is smaller than this range, sufficient crystallization promoting effect is not exhibited.

The polyester resin of the present invention was prepared by dissolving 2 g of polyester resin in 20 ml of a phenol / 2,1,1,2,2-tetrachloroethane 3/2 (volume ratio) mixed solvent and measuring the haze of the solution measured using a cell having an optical path length of 20 mm. Is preferably 40% or less. More preferably, it is 10% or less, More preferably, it is 5% or less. If it exceeds this range, the amount of transmitted light decreases in optical applications, and if the same amount of transmitted light is to be secured, it is not preferable because the film must be made extremely thin.

When the polyester resin of the present invention contains a crystal nucleating agent, the number average average diameter in the resin of the crystal nucleating agent or the crystal nucleating agent derivative particles is preferably 1.2 μm or less. Here, the crystal nucleating agent derivative particles refer to particles precipitated in the resin by the crystal nucleating agent. For example, when various metal salts such as alkali metal salts, alkaline earth metal salts, magnesium, and aluminum are added, the metal itself becomes precipitated particles due to a reducing component such as a phosphorus compound, or metal is disposed at the end of the polyester molecule. However, these particles are included in the crystal nucleating agent derivative particles. The number average particle diameter is more preferably 1.0 μm or less, further preferably 0.5 μm or less, and most preferably 0.3 μm or less. If it is larger than this range, the haze becomes large and it is not suitable for optical applications. Moreover, when the pattern to be heat-formed is a fine shape, the shape after heat-forming may be adversely affected.

The intrinsic viscosity (IV) of the polyester resin of the present invention is preferably 0.55 or more and 0.75 or less. A more preferable range is 0.57 or more and 0.7 or less, and a most preferable range is 0.58 or more and 0.65 or less. When it is larger than this range, the heat formability is lowered, and when it is smaller than this range, the heat resistance is lowered.

The polyester resin of the present invention is a surface forming agent, processability improver, antioxidant, ultraviolet absorber, light stabilizer, antistatic agent, lubricant, in addition to the above-mentioned crystal nucleating agent within the range not impairing the heat formability. Additives such as antiblocking agents, soft particles, plasticizers, antifogging agents, colorants, dispersants, infrared absorbers and the like can be added. The additive may be colorless or colored, but is preferably colorless and transparent so as not to impair the characteristics of the optical film. As a method for adding these additives, any of addition during polymerization, melt kneading, and solution kneading can be preferably applied. Among these, melt kneading is most preferable from the viewpoint of ease of polymerization control and cost.

Further, it may be alloyed with other resins as long as the heat formability is not impaired. Examples of the alloy component include various acrylics, polyesters, polycarbonates, cyclic olefins, etc., but it is desirable to contain the resin of the present invention in an amount of 50% by weight or more in the alloy composition, and the entire alloy composition satisfies the characteristics of the present invention. There is a need.

Hereinafter, although the manufacturing method of the polyester resin of this invention is described concretely, this invention is not restrict | limited to this.

The method for polymerizing the polyester resin of the present invention is not limited, and a known polymerization method such as an esterification method using a dicarboxylic acid and a glycol as a derivative, a transesterification method using a dicarboxylic acid diester and a glycol, or the like can be used.
Various diols can be used as the diol component. For example, aliphatic diols such as ethylene glycol, trimethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentylglycol, Cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalene diethanol, decahydronaphthalene diethanol, norbornane dimethanol, norbornane diethanol, tricyclodecane dimethanol, tricyclodecane diethanol, tetracyclododecane dimethanol, tetracyclo Saturated alicyclic primary diols such as decanediethanol, decalin dimethanol and decalin diethanol, 2,6-dihydroxy-9-oxabicyclo [3,3, ] Nonane, 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane (spiroglycol), 5-methylol-5-ethyl- Saturated heterocyclic primary diols containing cyclic ethers such as 2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane and isosorbide, other cyclohexane diols, bicyclohexyl-4,4′-diols, 2 , 2-bis (4-hydroxycyclohexylpropane), 2,2-bis (4- (2-hydroxyethoxy) cyclohexyl) propane, cyclopentanediol, 3-methyl-1,2-cyclopentanediol, 4-cyclopentene- Various cycloaliphatic diols such as 1,3-diol and adamantanediol, bisphenol A, Phenol S, styrene glycol, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9'-aromatic cyclic diols such as bis (4-hydroxyphenyl) fluorene can be exemplified. In addition to diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used. However, it is not limited to the glycol component specifically exemplified.

Of these, ethylene glycol is preferred from the viewpoint of reactivity and low cost. Further, from the viewpoint of heat resistance, a cyclic diol is also preferable, and as the cyclic diol, for example, spiroglycol, cyclohexanedimethanol, tricyclodecanedimethanol and the like are preferable. Of these, ethylene glycol is most preferred.

In addition, two or more types can be combined within a range that does not impair the object of the present invention. For example, heat resistance, reactivity, and cost can be adjusted by a combination of spiroglycol and ethylene glycol.

The dicarboxylic acid component of the polyester of the present invention is not particularly limited, and general ester forming derivatives of carboxylic acids can be used. As ester-forming derivatives, acid anhydrides such as terephthalic anhydride, acid halides such as acid chlorides corresponding to dicarboxylic acids, lower alkyl esters such as dimethyl terephthalate, and the like can be used. Here, for convenience, unless otherwise specified, dicarboxylic acid includes an ester-forming derivative of dicarboxylic acid. Specifically, the aromatic dicarboxylic acid includes, but is not limited to, phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, diphenylether-4,4′-dicarboxylic acid, 4,4'-diphenylmethanedicarboxylic acid, benzylmalonic acid and the like. Examples of chain aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, methylmalonic acid, ethylmalonic acid, 2,2-dimethylsuccinic acid, 2,3- Examples include dimethyl succinic acid, 2,3-dimethyl succinic acid, 3-methyl glutaric acid, and 3,3-dimethyl glutaric acid. Examples of alicyclic dicarboxylic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, 1,4-cyclohexanedione-2,5-dicarboxylic acid. 2,6-decalin dicarboxylic acid, 1,5-decalin dicarboxylic acid, 1,6-decalin dicarboxylic acid, 2,7-decalin dicarboxylic acid, 2,3-decalin dicarboxylic acid, 2,3-norbornane dicarboxylic acid, bicyclo Saturated alicyclic dicarboxylic acids such as [2,2,1] heptane-3,4-dicarboxylic acid, cis-5-norbornene-endo-2,3-dicarboxylic acid, methyl-5-norbornene-2,3 -Dicarboxylic acid, cis-1,2,3,6-tetrahydrophthalic acid, methyltetrahydrophthalic acid, 3 4,5,6-tetrahydrophthalic acid, unsaturated aliphatic dicarboxylic acids such as exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic acid can be exemplified. In addition to dicarboxylic acid, polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid can also be used as the polyfunctional component.

Of these, cyclic dicarboxylic acids are preferred from the viewpoint of heat resistance. Specifically, terephthalic acid and naphthalenedicarboxylic acid are preferable from the viewpoints of polymerizability, cost, and resin properties. As long as the object of the present invention is not impaired, these can be used alone or in combination of two or more. For example, Tg and Tm can be adjusted by using terephthalic acid and naphthalenedicarboxylic acid in combination.

When 2,6-naphthalenedicarboxylic acid is used as the copolymer component as the dicarboxylic acid component, it is preferable that 2,6-naphthalenedicarboxylic acid is 8 to 17 mol% in the dicarboxylic acid component. By being in this range, the thermal properties of the present invention can be expressed while using terephthalic acid and ethylene glycol, which are low in cost and excellent in polymerizability, as main copolymerization components. The more preferable copolymerization ratio of 2,6-naphthalenedicarboxylic acid is 10 to 15 mol%, most preferably 11 to 14 mol%.

The catalyst for producing the polyester of the present invention is not particularly limited, and various catalysts can be used. For example, effective catalysts for transesterification include alkali metal or alkaline earth metal compounds such as calcium acetate, magnesium acetate, lithium acetate, sodium acetate, manganese acetate, cobalt acetate, zinc acetate, tin acetate, alkoxide titanium, etc. Can be used. As the polymerization catalyst, antimony compounds such as antimony trioxide, germanium compounds such as germanium oxide, various titanium compounds such as alkoxide titanium, and composite oxides of aluminum and silica can be used. Examples of the stabilizer include phosphoric acid-based, phosphorous acid-based, phosphonic acid-based, and phosphinic acid-based compounds. Among these, these ester compounds are preferable from the viewpoint of suppressing the formation of foreign matters, and phosphonic acid ester derivatives are particularly preferable as foreign materials. From the viewpoint of formation suppression and melt heat resistance, triethylphosphonoacetate is specifically preferred. The phosphorus compound is preferably added at the beginning of the polycondensation reaction after the esterification reaction or after the transesterification reaction.

Specifically, when the polymerization method is a transesterification method, for example, when dimethyl terephthalate, dimethyl naphthalene dicarboxylate, or ethylene glycol is used, dimethyl terephthalate, dimethyl naphthalene dicarboxylate, or ethylene glycol is reacted so as to have a predetermined polymer composition. Charge into a container. At this time, the reactivity is improved by adding 1.7 to 2.3 mole times of ethylene glycol with respect to the total dicarboxylic acid component. After melting these at about 150 ° C., magnesium acetate is added as a catalyst and stirred. At 150 ° C., these monomer components become a homogeneous molten liquid. Subsequently, methanol is distilled while gradually raising the temperature to 235 ° C., and a transesterification reaction is performed. At the end of the ester reaction, triethylphosphonoacetate is added and water is evaporated after stirring. Furthermore, after adding an ethylene glycol solution of diantimony trioxide, the reaction product was charged into a polymerization apparatus, and while the temperature inside the apparatus was gradually raised to 285 ° C., the pressure inside the apparatus was reduced from normal pressure to 133 Pa or less. Distill the glycol. As the polymerization reaction proceeds, the viscosity of the reaction product increases. When the predetermined stirring torque is reached, the reaction is terminated, and the resin is discharged from the polymerization apparatus into a water tank in a strand shape. The discharged resin is rapidly cooled in a water tank, and after winding it is made into chips with a cutter. Here, when the target IV is 0.7 or more, the chip is temporarily formed at an IV lower than the target, and then the target IV is reduced under Tm of the chip, specifically, at a temperature of 170 to 230 ° C. and 133 Pa or less. It is also preferable to perform solid phase polymerization.

Next, the production of a heat-shaped optical film using the polyester resin of the present invention will be described, but the present invention is not limited thereto.

The composition of the heat-shaped optical film of the present invention may be a single layer film composed only of the polyester resin of the present invention, or may be a laminate composed of a plurality of resin layers. A laminate comprising a heat shaping layer made of a polyester resin and a support layer is preferred. In the case of such a laminated body, characteristics such as slipperiness and friction resistance, mechanical strength, and heat resistance can be imparted as compared with the case of a single layer film. At this time, the material of the base material of the support layer to be laminated is not particularly limited as long as the optical properties are not inhibited, and organic film base materials such as polyester, polycarbonate, acrylic, cycloolefin polymer, polyimide, epoxy, polyethylene, glass, etc. The inorganic base material is exemplified, but polyester, particularly polyethylene terephthalate is preferable from the viewpoint of adhesion between laminated layers, film-forming property, and cost.

In the case of a laminate, it is preferable to provide a heat shaping layer made of the polyester resin of the present invention on at least one outermost layer of the laminate. This is because the heat formability and heat resistance of the film surface are improved by providing the heat shaping layer comprising the polyester resin of the present invention in the outermost layer. Moreover, in the case of a laminated body, it is more preferable to provide the heat shaping layer which consists of the polyester resin of this invention in both outermost layers. Further, it is more preferable to have a laminated structure in which the front and back are symmetric when viewed from the center in the thickness direction of the laminated body. Satisfying such requirements is preferable because film curling caused by heat shaping, heat resistance test, and moist heat resistance test is reduced. The number of layers is not particularly limited as long as this requirement is satisfied, but the preferred number of layers is 3 or more.

As a method for producing the heat-shaped optical film of the present invention, for example, in the case of a film composed of a single layer film, the resin of the present invention is heated and melted in an extruder and extruded from a die onto a cast drum cooled to form a sheet. A processing method (melt cast method) can be mentioned. As another method, a sheet forming material is dissolved in a solvent, and the solution is extruded from a die onto a support such as a cast drum or an endless belt to form a film, and then the solvent is dried and removed from the film layer to form a sheet. A method of processing into a solution (solution casting method) or the like can also be used.

In addition, as a method for producing a laminate, a method in which a plurality of thermoplastic resins are charged into a plurality of extruders, melted and coextruded on a cast drum cooled from a die (coextrusion method), A method of laminating the raw material of the coating layer into a sheet made of a single film into an extruder, melt extrusion and extruding it from the die (melt laminating method), a film made as a single layer film and a heat-shaped film respectively A method of separately producing and thermocompression bonding with a heated group of rolls (thermal laminating method), a method of laminating via an adhesive (adhesion method), and other materials for film formation are dissolved in a solvent, and the solution is A method of coating on a film (coating method) or the like can be used.

The heat-shaped optical film of the present invention is preferably oriented in a uniaxial or biaxial direction. More preferably, it is oriented in the biaxial direction. By using an oriented film, it is possible to easily impart mechanical strength, dimensional stability, and the like preferable as a base material.

Among these, the configuration of the heat-shaped optical film of the present invention is particularly preferably a laminate, and more preferably biaxially oriented.

As stretching methods for orientation, sequential biaxial stretching methods (stretching methods that combine stretching in each direction, such as a method of stretching in the width direction after stretching in the longitudinal direction), simultaneous biaxial stretching methods (longitudinal direction) And a method of stretching them in the width direction at the same time) or a method combining them can be used, but the present invention is not limited to these stretching methods. In addition, excellent mechanical properties can be imparted by biaxially stretching the polyester film by these stretching methods.

Further, in the biaxially oriented polyester film of the present invention, it is preferable that the plane orientation coefficient (hereinafter sometimes referred to as fn) of at least one heat-shaped layer is 0.12 or less. Here, the plane orientation coefficient is a refractive index in the longitudinal direction, the width direction, and the thickness direction (Nx, Ny, and Nz, respectively) using an Abbe refractometer with sodium D line as a light source, and fn = (Nx + Ny) / 2-Nz. By satisfying these requirements, a biaxially oriented polyester film excellent in heat-forming formability can be obtained.

By setting the plane orientation coefficient of at least one heat-forming layer within the above-mentioned specific range, the resin constituting the thermoformed layer becomes an amorphous state with low orientation, and a fine high aspect ratio pattern and a large area are formed. It becomes possible. When the plane orientation coefficient is larger than 0.12, the orientation of the resin constituting the heat-shaped layer becomes strong and the elastic modulus becomes high, so that the above-described molding becomes impossible. Further, the plane orientation coefficient of at least one heat-shaped layer can be adjusted by the stretching ratio of the laminated film, the heat treatment temperature after biaxial stretching, and the heat treatment time as long as the effects of the present invention are not impaired. For example, it is possible to reduce the plane orientation coefficient of the molding layer by setting the draw ratio to a low ratio or increasing the heat treatment time. Although the lower limit of the plane orientation coefficient is not particularly set, it is preferably 0.05 or more in order to avoid deterioration in film forming property due to high heat treatment temperature and long heat treatment time.

As a method for satisfying such requirements, a temperature not lower than the melting endothermic peak temperature (Tm2 ′) of the resin constituting the heat-shaped layer after biaxial stretching and lower than the melting endothermic peak temperature (Tm1 ′) of the resin constituting the support layer. There is a method in which the effect of the present invention is manifested by applying a heat treatment. By performing such heat treatment, the resin constituting the heat-shaped layer becomes an amorphous state, and the resin constituting the support layer can maintain the orientation state without melting and improve the mechanical strength. is there. That is, it is preferable to set the heat treatment temperature after biaxial stretching in this range because a film having both formability and mechanical strength can be obtained in a consistent film forming process by coextrusion. The heat treatment temperature may be higher than the melting endothermic peak temperature Tm2 ′ of the resin constituting the heat shaping layer, but is preferably 5 ° C or higher, more preferably 10 ° C or higher, and further preferably 20 ° C. High temperature. By increasing the heat treatment temperature by 5 ° C. or more from the melting endothermic peak temperature Tm2 ′ of the resin constituting the heat shaping layer, the orientation relaxation of the resin constituting the heat shaping layer proceeds and the amorphous part increases. It is preferable because moldability is improved.

The preferred thickness (thickness, film thickness) of the biaxially oriented polyester film of the present invention is preferably in the range of 10 μm to 5 mm. More preferably, it is 20 μm to 2 mm, and still more preferably 20 μm to 200 μm.

Further, in the case of a laminate, it is preferable to provide a heat shaping layer made of the resin of the present invention having a thickness in the range of 1 μm to 30 μm on the substrate. Further, when the heat shaping layers are provided on both outermost layers, the thickness of each heat shaping layer is preferably 1 μm to 30 μm.

The thickness of the heat shaping layer has a strong influence on the heat shaping property. That is, the volume of the heat-shaped layer is preferably equal to the volume amount deformed by heat shaping, and more preferably the volume of the heat-shaped layer is larger than the volume amount deformed by heat shaping. More preferably, the thickness of the heat shaping layer is larger than the height at which the heat shaping layer is deformed. This is because the resin constituting the heat-shaped layer in the vicinity of the support layer is restricted in thermal motion by the support layer, and it is difficult to impart a shape by heat-forming.

Also, the shape imparted by heat shaping is preferably a prism shape with the hypotenuse of an isosceles right triangle as the base. By imparting a prism shape, a biaxially stretched polyester film having a high brightness enhancement effect can be obtained. The length (pitch) of the base of each prism shape is preferably in the range of 1 μm to 50 μm. More preferably, it is 5 μm to 25 μm. By setting it as this range, the favorable brightness improvement effect is acquired and the total thickness of a film can also be made small.

When the pitch is increased, the added shape becomes a noticeable screen. When the pitch is 50 μm, the height of the prism is 25 μm. For the reasons described above, the thickness of the heat-shaped layer is preferably larger than the height of deformation due to the shape to be applied, and is preferably about 30 μm. If a prism shape with a small pitch is provided by heat shaping, the influence of the wave nature of light becomes strong, a diffraction phenomenon occurs, and a sufficient brightness improvement effect cannot be obtained, which is not preferable. For this reason, if the thickness of the heat-shaped layer is less than 1 μm, the effect as a prism cannot be obtained sufficiently, which is not preferable because it is a biaxially oriented polyester film that is not suitable for heat-shaping.

Next, an example of a heat forming method using the heat shaping optical film and the heat shaping optical film laminate of the present invention will be described.

First, a surface layer made of the polyester resin of the present invention that heat-forms the heat-shaped optical film (or heat-shaped optical film laminate) of the present invention and a mold having concavities and convexities that are inverted patterns to be transferred. The film is heated in a temperature range not less than the glass transition temperature (Tg) and less than the melting point (Tm), the film and the mold are brought close to each other, pressed at a predetermined pressure, and held for a predetermined time. Next, the temperature is lowered while maintaining the pressed state. Finally, release the press pressure and release the film from the mold.

As a heat shaping method preferably employed in the present invention, in addition to a method of pressing a lithographic plate (lithographic pressing method), a roll-shaped mold having irregularities formed on the surface is used to form a roll-shaped sheet, and a roll It may be a roll-to-roll continuous molding to obtain a shaped molded body. Roll-to-roll continuous molding is superior to the lithographic press method in terms of productivity.

In the molding method preferably employed in the present invention, the heating temperature and the press temperature T1 are preferably in the range of the glass transition temperature Tg to Tg + 60 ° C. of the polyester resin of the present invention constituting the heat-shaped layer. If the glass transition temperature Tg of the resin constituting the heat shaping layer is not exceeded, the softening of the resin constituting the heat shaping layer has not sufficiently progressed, so that deformation when the mold is pressed is less likely to occur. The pressure required for molding becomes very high. If the temperature exceeds this range, the heating temperature and the press temperature T1 become too high, which is inefficient in energy, and the volume fluctuation during heating / cooling of the sheet is about one digit larger than that of the mold. The sheet cannot be released due to being bitten into the mold, and even if the sheet can be released, the accuracy of the pattern is deteriorated, or the pattern is partially lost, which is not preferable. In the molding method preferably employed in the present invention, by setting the heating temperature and the press temperature T1 within this range, both good moldability and mold release properties can be achieved.

In the molding method preferably employed in the present invention, the pressing pressure is preferably 0.5 to 50 MPa, although it depends on the plane orientation coefficient of the heat-shaped layer. More preferably, it is 1 to 30 MPa. If it is less than this range, the resin is not sufficiently filled in the mold, and the pattern accuracy is lowered. On the other hand, exceeding this range is not preferable because the required load increases, the load on the mold increases, and the repeated use durability decreases. By setting the press pressure within this range, good moldability and durability of the mold can be maintained.

In the molding method preferably employed in the present invention, the press pressure holding time is preferably in the range of 0 second to 10 minutes, depending on the plane orientation coefficient of the heat-shaped layer. Exceeding this range is not preferable because the tact time is too long, the productivity is not increased, the resin is thermally decomposed, and the mechanical strength of the molded sheet may be lowered. In the molding method preferably employed in the present invention, both good moldability and uniformity can be achieved by setting the holding time within this range.

In the molding method preferably employed in the present invention, the press pressure release temperature T2 is preferably lower than the press temperature T1 within the temperature range of the glass transition temperature Tg + 20 ° C. of the resin constituting the heat shaping layer. Exceeding this range is not preferable because the resin at the time of pressure release is softened, the fluidity is high, and the molding accuracy is lowered, for example, the pattern is deformed. In the molding method preferably employed in the present invention, by setting the press pressure release temperature T2 within this range, both good moldability and mold release properties can be achieved.

In the molding method preferably employed in the present invention, the mold release temperature T3 is preferably within the temperature range equal to or lower than the Tg. A temperature range of 20 ° C. to the Tg is more preferable. If it exceeds this range, the fluidity of the resin at the time of mold release is high, so that the pattern is deformed and the accuracy is lowered, or the sheet itself is deformed. In the molding method preferably employed in the present invention, by setting the temperature at the time of mold release within this range, it is possible to release the pattern with high accuracy and to suppress deformation of the sheet itself.

The molded product produced using the heat-shaped sheet of the present invention can be used for various applications. As an example of applications, optical circuits, optical connector members, prism sheets and other displays The member is exemplified.

The present invention will be described more specifically with reference to the following examples.

The physical properties were measured and the effects were evaluated according to the following methods.
(1) Thermal characteristics of resin pellets (glass transition temperature (Tg), melting point (Tm), heat of fusion (ΔHm), cold crystallization temperature (Tcc), etc.)
In accordance with JIS-K7121 (established in 1987), each value was calculated for the chart obtained at the time of 2nd cycle temperature rise using the following measuring device.

Apparatus: Differential scanning calorimeter DSCQ100 (manufactured by TA Instruments)
Measurement conditions: Under nitrogen atmosphere Measurement range: 50-280 ° C
Sample weight: 10 mg (using TA Instruments aluminum pan)
Temperature program:
1st cycle Room temperature → Temperature rise (16 ° C / min) → Hold at 50 ° C for 2 minutes → Temperature rise (16 ° C / min)
→ Hold at 280 ° C for 5 minutes → Take out from the electric furnace by a program and rapidly cool at room temperature (20 ° C) (Leave for 10 minutes)
2nd cycle 50 ° C 2 minutes hold → temperature rise (16 ° C / min) → 280 ° C → temperature drop (16 ° C / min) → 25 ° C
(2) Intrinsic viscosity (IV)
Measurement was performed at 25 ° C. using orthochlorophenol as a solvent.
(3) Resin solution haze 2 g of polyester was dissolved in 20 ml of a phenol / 1,1,2,2-tetrachloroethane 3/2 (weight ratio) mixed solvent, and a haze meter (suga Analysis was carried out by integrating sphere photoelectric photometry with HZ-1) manufactured by Test Instruments.
(4) Resin sodium element content 1 g of polyester was heated on an electric stove to incinerate the polymer, then placed in an electric furnace and treated at 650 ° C. for 1 hour to completely incinerate. This ashed product was dissolved in dilute hydrochloric acid to obtain a measurement solution, the absorbance was measured at a measurement wavelength of 589 nm using an atomic absorption measurement device, and the amount of sodium was calculated from a calibration curve. The content was calculated for the case of 30 ppm or more.
(5) Average particle diameter A part of the sheet is cut out from the center of the sheet, an ultrathin section having a thickness of 0.2 μm is prepared using a microtome, and observed with a transmission electron microscope (TEM) H-7100 manufactured by Hitachi, Ltd. About 100 dispersed particles, the primary particle diameter was measured, and the average value was defined as the dispersed particle diameter.
(6) Thermoforming formability After cutting out the cross section of the heat forming product and depositing platinum-palladium, photographs were taken using a scanning electron microscope S-2100A manufactured by Hitachi, Ltd., and the cross section was observed. It was.

The mold used for shaping has a shape in which a plurality of triangular prisms having a right-angled isosceles triangle (height 12 μm) with a vertical angle of 90 ° are formed on the surface in parallel with a pitch of 24 μm (cross section: figure 2 (a), perspective view: FIG. 2 (b)).

FIG. 2 (c) shows a molded product shaped using the mold. The average value of the ratio b / a of the height b (mold design value 12 μm) and the ½ double width a (mold design value 12 μm) of this molded product pattern convex portion is 0.8 or more: ○
0.7 or more and less than 0.8: △
Less than 0.7: ×
It was. If an evaluation result is (triangle | delta) or (circle), it is favorable (the direction of (circle) is still more favorable).
(7) Luminance retention rate The prism sheet formed by heat-molding the resin of the present invention is subjected to a heat resistance test at 85 ° C. for 250 hours, and (luminance after the heat resistance test / luminance before the test) × 100 (%) is the luminance retention rate. It was.

In the heat resistance test, the prism sheet was fixed on the Kapton sheet with tape at the four corners and treated in a hot air oven at 85 ° C. for 250 hours.

For luminance measurement, a schematic backlight configuration in evaluation is shown in FIG.
A 21 inch (330 mm × 410 mm: diagonal 520 mm) direct type backlight (casing, reflective film, d in FIG. 3, e in fluorescent tube partial view 3), a diffusion plate (Nitto Jushi Kogyo Co., Ltd.) in order from the light source side. “Clarex” DR-65C, c) in FIG. 3, diffusion sheet (manufactured by Kimoto Co., Ltd., “Light-up” 188GM3, b in FIG. 3), prism formed by heat-molding the resin of the present invention A sheet (a in FIG. 3) was installed, turned on at 12 V, and the luminance in the front direction was measured using a luminance unevenness analyzer Eye-Scale 3 manufactured by I-System Co., Ltd. after 1 hour. Here, the prism sheet was installed so that the longitudinal direction of the prism row was parallel to the linear portion of the fluorescent tube.

The measurement position was performed on a line shifted to the right or left by 25 mm from the center of the backlight in the direction perpendicular to the linear portion of the fluorescent tube. The brightness was evaluated as an average value of the measurement positions.

The backlight configuration for evaluation was as follows.
(Fluorescent tube)
Diameter: 3mm
Number: 12 Adjacent spacing (pitch): 25 mm (= 2p)
Distance between tube center and reflector (lower side): 5mm
Distance between tube center and member (upper side) 10mm (= h)
θ: 51.3 ° (tan θ = p / h = 1.25)
(Reflective sheet)
Lumirror (registered trademark) 188E60L manufactured by Toray Industries, Inc.

All of the above measurements were performed at room temperature of 23 ° C. and humidity of 65%.
(Reference example) Preparation of titanium catalyst (titanium lactate sodium chelate compound) Lactic acid (226.8 g, 2.52 mol) was dissolved in warm water (371 g) in a 3 liter flask equipped with a stirrer, condenser and thermometer. Stir. To this stirred solution, titanium tetraisopropoxide (288 g, 1.0 mol) was slowly added from a dropping funnel. The mixture was heated to reflux for 1 hour to produce a cloudy solution from which the isopropanol / water mixture was distilled under reduced pressure. The product was cooled to a temperature below 70 ° C. and a 32 wt% aqueous solution of sodium hydroxide (380 g, 3.04 mol) was slowly added to the stirred solution via a dropping funnel. The resulting product was filtered and then mixed with ethylene glycol (504 g, 8 mol) and heated under reduced pressure to remove isopropanol / water and a slightly cloudy light yellow product (titanium content 5. 6 wt%) was obtained.

(8) Plane orientation coefficient (fn)
A layer for measuring a plane orientation coefficient (hereinafter referred to as a measurement layer) using an Abbe refractometer is adhered to the glass surface, and then the refractive index in the longitudinal direction, the width direction, and the thickness direction using the sodium D line as a light source (respectively). , Nx, Ny, Nz), and the plane orientation coefficient fn of the measurement layer was determined from the following formula. Of the fn determined by this method, the value of the layer having a low fn was defined as fn of the film.
fn = (Nx + Ny) / 2−Nz.

Example 1
Weigh each at a ratio of 86.2 parts by weight of dimethyl terephthalate and 14.8 parts by weight of dimethyl 2,6-naphthalenedicarboxylate and 62.6 parts by weight of ethylene glycol (2 moles of dicarboxylic acid component). After charging and melting the contents at 150 ° C., 0.06 parts by weight of magnesium acetate tetrahydrate, 0.02 parts by weight of antimony trioxide and 0.003 parts by weight of lithium acetate dihydrate were added and stirred as a catalyst. .

The temperature was raised to 190 ° C. over 60 minutes, further raised to 200 ° C. over 60 minutes, and then methanol was distilled while raising the temperature to 240 ° C. over 90 minutes. After distillation of a predetermined amount of methanol, an ethylene glycol solution containing 0.04 part by weight of triethylphosphonoacetate was added as a catalyst deactivator and stirred for 5 minutes to stop the transesterification reaction.

Thereafter, the reaction product is charged into a polymerization apparatus, and while the temperature in the apparatus is increased from 235 ° C. to 290 ° C. over 90 minutes, the pressure in the apparatus is reduced from normal pressure to vacuum to distill ethylene glycol. The reaction is terminated when the viscosity of the reaction product increases with the progress of the polymerization reaction and reaches a predetermined stirring torque. At the end of the reaction, the inside of the polymerization apparatus was returned to normal pressure with nitrogen gas, the valve at the bottom of the polymerization apparatus was opened, and gut-shaped polyester was discharged into the water tank. The discharged polyester resin was quenched in a water tank and then cut with a cutter to form a chip.

The obtained polyester chip was put into a water tank filled with 95 ° C. ion exchange water and treated with water for 5 hours. The chip after the water treatment was separated from the water by a dehydrator. Fines contained in the polyester chips were also removed by this water treatment. A polyester resin A was thus obtained.

Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

This polyester resin A and PET resin (IV 0.65) were each vacuum-dried at 170 ° C. for 3 hours and then melted at 280 ° C. in separate extruders, both outermost layers being resin A and PET resin being the inner layer. The laminated resin extruded from the layer coextrusion die was closely cooled and solidified while applying an electrostatic charge to a cooling drum maintained at 25 ° C. Next, the cast film was stretched 3.3 times in a longitudinal direction at 90 ° C. by a roll type stretching machine. Next, it was introduced into a tenter, stretched by 3.4 times at 110 ° C., and then heat treated in a temperature zone controlled at 238 ° C., followed by 4% relaxation treatment at 170 ° C. in the width direction, and then to room temperature. The film was cooled and wound to obtain a three-layer laminated film having a surface layer thickness of 20 μm, an inner layer thickness of 148 μm, and a total thickness of 188 μm.

After that, heat molding was performed. The heat forming flow is shown in FIG. The mold has the prism shape shown in FIG. 2, and the uneven surface of the mold (g in FIG. 4) whose temperature is controlled by this film (h in FIG. 4) and the heating / cooling plate (f in FIG. 4). Was heated to 120 ° C., pressed at 2.5 MPa, and held for 30 seconds. Thereafter, the mold was cooled to 70 ° C., and then the press was released and released from the mold to obtain a resin molded product.

Table 1 shows the results of the 85 ° C. luminance retention rate of the obtained molded product.

Example 2
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition ratio was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

A three-layer laminated film was obtained in the same manner as in Example 1 except that this polyester resin was used as a sublayer, and then a heat-forming product was obtained. Table 1 shows the results of the 85 ° C. luminance retention rate of the obtained molded product.

Example 3
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition ratio was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained folded ester resin.

Example 4
Lithium acetate dihydrate was removed from the added catalyst after melting the monomer, and 5 parts by weight of sodium montanate (Licomont NaV101 manufactured by Clariant Japan Co., Ltd.) was added 5 minutes after addition of the ethylene glycol solution of the catalyst deactivator triethylphosphonoacetate. A polyester resin was obtained in the same manner as in Example 1 except that was added. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 5
A polyester chip of IV0.53 was obtained in the same manner as in Example 4 except that the amount of diantimony trioxide was changed to 0.1 parts by weight for solid-phase polymerization and the ultimate stirring torque at the end of the polycondensation reaction was lowered. .

The obtained chip was vacuum-dried at 150 ° C. for 4 hours, and then subjected to solid-phase polymerization at 210 ° C. for 4 hours under a vacuum of 133 Pa or less to obtain a polyester resin having an IV of 0.72. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 6
Example 1 was repeated except that lithium acetate dihydrate was removed from the added catalyst after melting the monomer, and 0.3 parts by weight of sodium acetate was added 5 minutes after addition of the ethylene glycol solution of the catalyst deactivator triethylphosphonoacetate. To obtain a polyester resin. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 7
A polyester resin was obtained in the same manner as in Example 6 except that the amount of sodium acetate added was changed to 0.02 parts by weight. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 8
A polyester resin was obtained in the same manner as in Example 6 except that the amount of sodium acetate added was changed to 0.5 parts by weight. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

The solution haze of the resin was high and the initial luminance was 5% lower than that of Example 1, but there was no problem with the prism sheet characteristics.

Example 9
30 parts by weight of talc (SG-95, nominal particle size: 2.8 μm) manufactured by Nippon Talc Co., Ltd., together with 300 parts by volume of ethylene glycol and 300 parts by volume of glass beads (average particle size: 50 μm), 5 at 3000 rpm using a jet agitator. The mixture was stirred at high speed for a period of time, and the glass beads were removed with a membrane filter to obtain a talc ethylene glycol slurry (average particle size 0.8 μm).

Implemented except that lithium acetate dihydrate was removed from the added catalyst after melting the monomer and talc EG slurry was added to 0.3 parts by weight of talc 5 minutes after addition of ethylene glycol solution of catalyst deactivator triethylphosphonoacetate A polyester resin was obtained in the same manner as in Example 1. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 10
30 parts by weight of talc (SG-95, nominal particle size: 2.8 μm) manufactured by Nippon Talc Co., Ltd., together with 300 parts by volume of ethylene glycol and 300 parts by volume of glass beads (average particle size: 50 μm), are mixed at 3000 rpm with a jet agitator. The mixture was stirred at high speed for a period of time, and the glass beads were removed with a membrane filter to obtain talc ethylene glycol slurry (average particle size 1.1 μm).

A polyester resin was obtained in the same manner as in Example 9 except that the talc EG slurry to be added was changed to this slurry. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 11
30 parts by weight of talc (SG-95, nominal particle size: 2.8 μm) manufactured by Nippon Talc Co., Ltd., together with 300 parts by volume of ethylene glycol and 300 parts by volume of zirconia beads (average particle size: 300 μm), 6 000 rpm with a jet agitator. The mixture was stirred at high speed for a period of time, and the glass beads were removed with a membrane filter to obtain a talc ethylene glycol slurry (average particle size 0.4 μm).

A polyester resin was obtained in the same manner as in Example 9 except that the talc EG slurry to be added was changed to this slurry and the addition amount was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 12
30 parts by weight of talc (SG-95, nominal particle size 2.8 μm) manufactured by Nippon Talc Co., Ltd., together with 300 parts by volume of ethylene glycol and 300 parts by volume of glass beads (average particle size 50 μm), 1 at 1000 rpm with a jet agitator The mixture was stirred at high speed for a period of time, and the glass beads were removed with a membrane filter to obtain a talc EG slurry (average particle size: 2.0 μm).

Example 13
10 parts by weight of alumina particles having an average particle size of 0.07 μm and 90 parts by weight of ethylene glycol were stirred with a dissolver at room temperature for 2 hours to obtain an ethylene glycol slurry of alumina particles.

The charged monomers were weighed at a ratio of 87.8 parts by weight of dimethyl terephthalate, 16.5 parts by weight of spiroglycol, and 56.1 parts by weight of ethylene glycol (2 moles of the dicarboxylic component), and charged into the transesterification reactor. After melting the product at 150 ° C., 0.06 part by weight of manganese acetate tetrahydrate as a catalyst and 0.002 part by weight of titanium catalyst prepared in Reference Example were added and stirred.

The temperature was raised to 190 ° C. over 60 minutes, further raised to 200 ° C. over 60 minutes, and then methanol was distilled while raising the temperature to 240 ° C. over 90 minutes. After distillation of a predetermined amount of methanol, an ethylene glycol solution containing 0.04 part by weight of trimethyl phosphoric acid as a catalyst deactivator was added and stirred for 5 minutes to stop the transesterification reaction. After 5 minutes, alumina particles Was added to an alumina EG slurry containing 0.3 part by weight.
Thereafter, a polymerization reaction was carried out in the same manner as in Example 1 to obtain a polyester resin. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 14
A polyester resin was obtained in the same manner as in Example 13 except that the copolymer composition was changed and the alumina slurry was not added. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 15
A polyester resin was obtained in the same manner as in Example 9 except that the copolymer composition ratio was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 16
A polyester resin was obtained in the same manner as in Example 9 except that the copolymer composition ratio was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 17
The charged monomers were 89.1 parts by weight of dimethyl terephthalate, 2.0 parts by weight of dimethyl isophthalate, 10.0 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 63.2 parts by weight of ethylene glycol (2 mols of the dicarboxylic acid component). Were mixed in a transesterification apparatus, and the contents were melted at 150 ° C. Then, 0.06 parts by weight of manganese acetate tetrahydrate and 0.02 parts by weight of antimony trioxide were added as a catalyst and stirred. did.

The temperature was raised to 190 ° C. over 60 minutes, further raised to 200 ° C. over 60 minutes, and then methanol was distilled while raising the temperature to 240 ° C. over 90 minutes. After distillation of a predetermined amount of methanol, an ethylene glycol solution containing 0.04 part by weight of triethylphosphonoacetate was added as a catalyst deactivator, and after stirring for 5 minutes, 0.02 part by weight of sodium acetate was added for 5 minutes. The transesterification reaction was stopped by stirring.

Thereafter, a polymerization reaction was carried out in the same manner as in Example 1 to obtain a polyester resin. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Example 18
A polyester resin was obtained in the same manner as in Example 2 except that the polymerization target torque was changed for the purpose of changing IV. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Since the resin IV was low, the luminance retention rate was lower than that in Example 2, but the retention rate was 96.8%.

Comparative Example 1
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition ratio was changed and the press temperature was 115 ° C. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

The Tm of the resin was high and the heat-forming formability was poor due to insufficient heat treatment.

Comparative Example 2
A three-layer laminated film was obtained in the same manner as in Example 1 except that a PET / N copolymer (NOPLA KE831) manufactured by Kolon Co., Ltd. was used as a sublayer as a resin, followed by heat shaping. Since the IV of the resin was too high, the heat formability was poor.

Comparative Example 3
A polyester resin was obtained in the same manner as in Example 1 except that the amount of diantimony trioxide added was changed and solid phase polymerization was carried out after chipping for the purpose of increasing IV. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

A three-layer laminated film was obtained in the same manner as in Example 1 except that this polyester resin was used as a sublayer, and then a heat-forming product was obtained. Since the IV of the resin was too high, the heat formability was poor.

Comparative Example 4
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition ratio was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

The luminance retention was low because the resin was amorphous.

Comparative Example 5
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition was changed and the press temperature was changed to 110 ° C. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

The resin Tg was low and the luminance retention was low.

Comparative Example 6
A polyester resin was obtained in the same manner as in Example 6 except that the amount of sodium acetate added was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

Moldability and luminance retention were good, but the solution haze of the resin was high, and the initial luminance was 10% or more lower than that of Example 1.

Comparative Example 7
A polyester resin was obtained in the same manner as in Example 1 except that the copolymer composition was changed. Table 1 shows the IV, solution haze, and thermal characteristics of the obtained polyester resin.

The resin Tg was low and the luminance retention was low.

Reference Example A three-layer laminated film was obtained in the same manner as in Example 1 except that the temperature of the heat treatment zone was 220 ° C., and then a heat-formed product was obtained. Since appropriate film forming conditions were not taken, the obtained molded product had poor moldability.

Claims

A polyester resin for a heat-shaping optical film having a glass transition temperature (Tg) of 83 ° C. or higher, a melting point (Tm) of 230 ° C. or lower, and a crystal melting heat (ΔHm) of 0.3 J / g or higher.
2. The heat-shaped optical film according to claim 1, wherein a temperature difference (ΔTcg: Tcc−Tg) between the temperature rising crystallization temperature (Tcc) and the glass transition point (Tg) is 50 to 90 ° C. Polyester resin.
The polyester resin for heat-shaped optical film according to claim 1 or 2, wherein the polyester is a copolymer comprising a terephthalic acid residue, a 2,6-naphthalenedicarboxylic acid residue, and an ethylene glycol residue.
The polyester resin for heat-shaped optical film according to any one of claims 1 to 3, wherein the 2,6-naphthalenedicarboxylic acid residue is 8 to 17 mol%.
5. The polyester resin for heat-shaped optical film according to claim 1, further comprising a crystal nucleating agent.
6. The polyester resin for heat-shaped optical film according to claim 5, wherein the number average average diameter of crystal nucleating agent or crystal nucleating agent derivative particles in the resin is 1.2 μm or less.
The polyester resin for heat-shaped optical film according to any one of claims 5 to 6, wherein the crystal nucleating agent is an organic carboxylic acid sodium salt.
The polyester resin for heat-shaped optical film according to claim 7, wherein the sodium element content is 50 to 1500 ppm with respect to the whole polyester resin.
The polyester resin for heat-shaped optical film according to any one of claims 5 to 6, wherein the crystal nucleating agent is talc.
2 h of polyester resin is dissolved in 20 ml of phenol / 1,1,2,2, tetrachloroethane 3/2 (volume ratio) mixed solvent, and the haze of the solution measured using a cell having an optical path length of 20 mm is 40% or less. The polyester resin for a heat-shaped optical film according to any one of claims 1 to 9, wherein:
The polyester resin for heat-shaped optical film according to any one of claims 1 to 10, wherein IV (intrinsic viscosity) is 0.55 or more and 0.75 or less.
A biaxially oriented film comprising a layer made of the polyester resin according to any one of claims 1 to 11 and having a layer made of the polyester resin having a plane orientation coefficient of 0.12 or less, wherein 1 to 30 μm is laminated on at least one outermost layer. Polyester film.
A biaxially oriented polyester film having a prism-shaped layer made of the polyester resin, wherein the heat-forming layer made of the polyester resin according to any one of claims 1 to 11 is laminated on at least one outermost layer in an amount of 1 to 30 μm.