JP3142366B2 - Copolyester and film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyester, and more particularly, to an aromatic copolyester for a thin film having excellent heat sealing properties and a thin film thereof.

[0002]

2. Description of the Related Art Aromatic polyesters represented by polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have excellent heat resistance, mechanical strength and gas permeability. Due to its balanced physical properties, it is widely used in engineering plastics in a wide range of fields. However, these polyesters have extremely low heat-sealing performance when considered for film applications, making bag making difficult.
It has a drawback that gas permeation resistance, which is an excellent characteristic of resin, cannot be used effectively.

[0003]

DISCLOSURE OF THE INVENTION In view of the above problems, the present inventors have conducted intensive studies to obtain a copolymerized polyester which is excellent in heat resistance and gas permeation resistance as well as heat sealing performance. The present inventors have found that a copolymerized polyester in which a specific amount of a specific comonomer unit is introduced into an aromatic polyester is suitable for use in a film as described above, and have completed the present invention. That is, in the present invention, when polymerizing a polyester whose main repeating unit is tetramethylene terephthalate, 10 to 30 mol% of diphenic acid or an alkyl ester thereof with respect to all carboxylic acid components constituting the polyester, and cyclohexanediol or The present invention relates to a copolymerized polyester obtained by introducing 10 to 30 mol% of cyclohexanedimethanol to all diol components constituting the polyester, and a film obtained by thinning the copolymerized polyester by a T-die method or an inflation method. .

The starting compounds required to form the copolymerized polyester of the present invention will be described in order. The polytetramethylene terephthalate unit, which is the main repeating unit, is composed of terephthalic acid or its dialkyl ester as a carboxylic acid component and a diol. 1,4 as an ingredient
-Butanediol can be introduced by using it as a monomer raw material. Here, dimethyl terephthalate is preferred as the dialkyl ester of terephthalic acid.

The present invention is characterized in that diphenic acid or an alkyl ester thereof is used in an amount of 10 to 30 mol% based on all carboxylic acid components constituting the polyester. From the viewpoint of reactivity, dimethyl diphenate is preferred. In the present invention, the introduced amount of diphenic acid or its alkyl ester is based on all carboxylic acid components.
10 to 30 mol%. When the introduction amount of diphenic acid or its alkyl ester is less than 10 mol%, even if the following cyclohexanediol or cyclohexane dimethanol is used in excess of 30 mol%, the melting point is too high. If it is kept, decomposition of the polyester is remarkable, which is not preferable. If the amount of diphenic acid or its alkyl ester exceeds 30 mol%,
Even if the introduction amount of the following cyclohexanediol or cyclohexanedimethanol is less than 10 mol%,
The heat resistance of the resulting polyester is not sufficient and is not preferred.

Further, the present invention is characterized in that cyclohexanediol or cyclohexanedimethanol is used in an amount of 10 to 30 mol% based on all diol components constituting the polyester, and cyclohexanediol or cyclohexanedimethanol which is a comonomer component is used as the polyester. Again, from the viewpoint of polymerization reactivity, 1,4-cyclohexanedimethanol having a high boiling point is preferable. Further, the ratio of the cis-form to the trans-form of cyclohexanedimethanol is not particularly limited. In the present invention, the amount of cyclohexanediol or cyclohexanedimethanol introduced is from 10 to 30 mol% based on all diol components. When the amount of cyclohexanediol or cyclohexanedimethanol introduced is 10
If the amount is less than 30 mol%, even if the above-mentioned diphenic acid or its alkyl ester is used in excess of 30 mol%, the melting point is too high. When the amount of cyclohexanediol or cyclohexanedimethanol introduced exceeds 30 mol%, even if the amount of diphenic acid or its alkyl ester introduced is less than 10 mol%, the heat resistance of the obtained polyester is not sufficient. Is not preferred.

The copolyester of the present invention may be a copolyester containing a small amount of other comonomers in addition to the above comonomers. Other comonomer components include, for example, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, aromatic dicarboxylic acids other than diphenic acid such as 4,4'-diphenyldicarboxylic acid and derivatives thereof, adipic acid, sebacic acid, succinic acid, etc. Aliphatic dicarboxylic acids and derivatives thereof, aromatic tricarboxylic acids and derivatives thereof such as trimesic acid and trimellitic acid, aromatic hydroxycarboxylic acids and derivatives thereof such as hydroxybenzoic acid and hydroxynaphthoic acid, ethylene glycol, propanediol and butenediol , Low molecular weight glycols such as hexanediol, high molecular weight glycols such as polyethylene oxide glycol and polybutylene oxide glycol, bisphenol A, bisphenol S, 4,4'-
Examples thereof include aromatic diols such as hydroxydiphenyl, and ethylene oxide and propylene oxide adducts thereof, and polyhydroxy compounds such as pentaerythritol.

The copolymerized polyester of the present invention can be prepared by using the above-mentioned monomer raw material and a polycondensation catalyst such as titanium tetrabutoxide in a molten state, in a solid It can be manufactured in a state or a combination of both.

[0009] The present invention also provides a resin composition in which the above-mentioned copolymerized polyester is supplemented with another thermoplastic resin or an inorganic filler or an organic additive, if necessary, within a range not to impair the effects of the present invention. Are included in the range. The thermoplastic resin used in this case is not particularly limited. Polyolefins such as polyethylene, polypropylene, polybutadiene, and polyisoprene; polyvinyl compounds such as polystyrene and polyvinyl chloride; aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate; Group polyesters, polyamides, wholly aromatic polyamides, polycarbonates, polyphenylene sulfides, polyphenylene oxides, polyacetals, fluororesins, and the like. These thermoplastic resins can be used as a mixture of two or more kinds. As the inorganic filler, depending on the purpose of use, various fibrous, powdery,
A plate-like filler can be blended. Examples of the fibrous filler include glass fiber, asbestos fiber, silica fiber, silica / alumina fiber, alumina fiber, zirconia fiber,
Silicon nitride fiber, boron nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium,
Examples include fibrous materials of metals such as copper and brass. On the other hand, as the particulate filler, carbon black, graphite, silica,
Quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, iron oxide, titanium oxide, zinc oxide, antimony trioxide , Metal oxides such as alumina, calcium carbonate, metal sulfates such as magnesium carbonate,
Other examples include ferrite, silicon carbide, silicon nitride, and various metal powders. Examples of the plate-like filler include mica, glass flake, various metal foils, and the like. These inorganic fillers can be used as a mixture of two or more kinds. Further organic additives include heat stabilizers, antioxidants,
UV absorbers, antistatic agents, flame retardants, flame retardant aids, coloring agents such as dyes and pigments, lubricants for improving fluidity and mold release,
Lubricants, crystallization accelerators and the like can be used.

As a method for forming a film or sheet from the copolymerized polyester, a usual T-die method or inflation method is used. Films made of PET or PBT have a narrow heat sealable temperature range and are difficult to heat seal, but the copolymerized polyester resin film obtained by the present invention has a low heat seal temperature and a wide heat sealable temperature range. Therefore, heat sealing is extremely easy and is suitable as a packaging material. If the thickness of the film or sheet is referred to, if the thickness is too small, the mechanical strength of the film or sheet itself is not exhibited, which is not practically preferable. However, when the thickness exceeds a certain limit, the heat sealing performance is reduced and the effect of the invention is reduced, which is not preferable. Therefore, the range of the preferred thickness of the film or sheet is specified to be 10 to 500 μm, more preferably 15 to 300 μm.
It is.

[0011]

The copolymerized polyester of the present invention has excellent heat resistance, mechanical strength, gas permeation resistance, etc., and excellent heat sealing performance, so that it is suitable for film applications. The film is particularly suitable for bag making applications, especially for food applications for microwave cooking. The copolyester of the present invention can be applied to the fields of extrusion molding and injection molding of tubes and pipes around heat sources, around transportation engines, around invention parts of electric appliances, etc. It is possible.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1 157.0 g (0.80 mol) of dimethyl terephthalate (DMT)
117.2 g (1.30 mol) of 1,4-butylene glycol (BG),
54.1 g (0.20 mol) of dimethyl diphenate (DMDP), 14.4 g (0.10 mol) of cyclohexanedimethanol (CHDM),
A certain amount of transesterification catalyst (tetrabutyl titanate)
At the same time, the mixture was charged into a reactor equipped with a stirrer and a distilling tube, and after sufficiently purging with nitrogen, the temperature was raised to 160 ° C. under normal pressure to start stirring. Further, the temperature was gradually increased, and methanol as a by-product was distilled off. When the temperature reached 240 ° C., the pressure in the reactor was gradually reduced, and stirring was continued at a pressure of 0.2 torr for 2 hours to obtain a copolymerized polyester having an intrinsic viscosity of 0.79. The physical properties of the obtained polyester were measured as shown below.

[0013] Copolymerization diphenic acid unit with respect to the acid component in the polyester and cyclohexanedimethanol units introduction rate was -d trifluoroacetic acid and solvent ¹ H-
Determined from NMR measurements. The glass transition point (Tg) and melting point (Tm) were measured based on JIS K 7121. This copolymerized polyester was melted at 240 ° C.
The film was extruded into a cooling roll to produce a film having a thickness of 100 μm. In order to examine the heat sealing performance of this film, the upper limit and lower limit (heat sealable temperature range) of the temperature at which the peel strength becomes 2 kgf or more at a sealing time of 1 second were obtained based on JIS K. Table 1 shows the results.

Examples 2 to 3 Polymerization was carried out in the same manner as in Example 1 except that the charged composition was changed to obtain copolymerized polyesters in which the amounts of DMDP and CHDM introduced were variously changed, and evaluated in the same manner as in Example 1. did. Table 1 shows the results.

Comparative Example 1 A copolymerized polyester in which only CHDM was introduced without using DMDP was obtained and evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 A copolymerized polyester in which only DMDP was introduced without using CHDM was obtained and evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1 without using DMDP and CHDM to obtain PBT, which was evaluated in the same manner as in Example 1. Table 1 shows the results
Shown in

[0018]

[Table 1]

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (4)

(57) [Claims] When a polyester having a main repeating unit of tetramethylene terephthalate is polymerized, diphenic acid or its alkyl ester is used in an amount of 10 to 30 mol% based on all carboxylic acid components constituting the polyester, and cyclohexanediol or cyclohexane. A copolymerized polyester obtained by introducing dimethanol in an amount of 10 to 30 mol% based on all diol components constituting the polyester. 2. The copolymerized polyester according to claim 1, wherein the diphenic acid or its alkyl ester is dimethyl diphenate. 3. The copolymerized polyester according to claim 1, wherein the cyclohexanediol or cyclohexanedimethanol is 1,4-cyclohexanedimethanol. 4. A copolyester film obtained by thinning the copolyester according to claim 1 by a T-die method or an inflation method.