JPH06122809A - Polyester resin composition for extrusion molding - Google Patents

Abstract

PURPOSE:To obtain a polyester resin composition for extrusion molding capable of providing a molded article having excellent flexibility, transparency and block resistance only by extrusion molding. CONSTITUTION:This polyester resin A composition for extrusion molding comprises 10-95wt.% crystalline polyester resin having 4cal/g or more heat of fusion and 30 deg.C or lower glass transition temperature and 90-5wt.% polyester resin B having a difference in solubility parameter between the polyester resin A and the polyester resin B of 0.2 or more and 0.6 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin composition for extrusion molding which does not require a stretching step and can give a molded article excellent in transparency and flexibility.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride resins have been mainly used for molded articles such as films and pipes which are required to have flexibility and transparency. The vinyl chloride-based resin is excellent in the transparency and flexibility described above, and also has excellent properties such that it is difficult for molded articles to block each other.

However, in order to have such excellent properties, it is essentially necessary to include a plasticizer, and the plasticizer migrates to contaminate the surroundings or the resin is added by the addition of the plasticizer. There was a problem that the characteristics of changed. Further, there is a problem that the vinyl chloride resin is also inferior in solvent resistance.

Further, vinyl chloride resins are difficult to decompose from the viewpoints of environmental pollution, acid rain, etc., which have recently been regarded as important, and hydrogen chloride is generated during combustion. The demand for alternative materials is increasing.

Polyester resin has attracted attention as an alternative material to vinyl chloride resin because it has excellent transparency in an amorphous state and does not generate a toxic gas when burned. Amorphous polyethylene terephthalate or the like has been used in place of.

[0006]

However, in order to make the polyester resin to have flexibility, it is necessary to set the glass transition point to room temperature or lower in order to use it as a substitute material for a soft or semi-hard vinyl chloride resin. However, such a resin is likely to cause blocking and deformation in an amorphous state. On the other hand, crystalline polyester resins generally lack transparency, and no suitable plasticizer that simultaneously imparts flexibility and transparency to polyester has been found.

To meet these requirements, a long-chain glycol such as polytetramethylene glycol or a long-chain fatty acid such as dimer acid is copolymerized with polyester to have crystallinity and a glass transition. It is known that a polyester film excellent in transparency and flexibility can be obtained by forming a polyester copolymer resin having a point of not higher than room temperature into a film and stretching it.

However, even when such a polyester copolymer resin is not used, its transparency is insufficient when it is not stretched, while when it is stretched, its thickness is restricted due to stretching. Its shape was also limited to a film.

In view of the above problems, the present invention is a polyester resin composition for extrusion molding, which is capable of obtaining a molded article having excellent flexibility, transparency and blocking resistance only by performing extrusion molding. The purpose is to obtain.

[0010]

The polyester resin composition for extrusion molding of the present invention comprises 10 to 95% by weight of a crystalline polyester resin A having a heat of fusion of 4 cal / g or more and a glass transition temperature of 30 ° C. or less, The polyester resin is characterized by comprising 90 to 5% by weight of a polyester resin B having a solubility index difference of 0.2 or more and 0.6 or less.

The polyester resin A has a heat of fusion of 4 ca.
It is a crystalline resin having a glass transition temperature of 30 ° C. or lower at 1 / g or more. The heat of fusion is measured by the differential scanning calorimeter (DS
Using C), the value of the endothermic amount at the maximum point of the endothermic energy at the time of crystal melting when measured with a sample of 10 mg and a heating rate of 20 ° C./min was taken as a value converted per unit weight.
The glass transition temperature was taken as the rising point of the endothermic peak at the transition point when measured under the same conditions.

The heat of fusion of the polyester resin A is 4 ca.
If it is less than 1 / g, the crystallinity is low and blocking occurs. Therefore, it is necessary to be 4 cal / g or more.
It is more preferably 1 / g or more. The glass transition temperature of the polyester resin A needs to be 30 ° C. or lower, and preferably 0 ° C. or lower, from the viewpoint of flexibility of the polyester resin composition.

Crystallization temperature of polyester resin A (T
It is desirable that cc) is 50 ° C. or higher. The temperature-decreasing crystallization temperature (Tcc) referred to here is 2 mg after placing 10 mg of a sample on a differential scanning calorimeter and heating the sample to the melting point or higher.
It is the rising temperature of the exothermic peak when cooled at a rate of 0 ° C / min.

The polyester resin B is a resin having a solubility index difference from the polyester resin A of 0.2 or more and 0.6 or less.

The solubility index was calculated using the following relational expression. (Solubility index) ² = 1.44 (ΣU / ΣV) (where U is the cohesive energy of the group forming the polymer,
V is the molecular volume of the group forming the polymer. )

When the difference between the solubility index of polyester resin B and the solubility index of polyester resin A is less than 0.2, the two resins are compatible with each other and the crystallinity of polyester resin A is impaired, resulting in a resin composition. Comes to blocking. On the other hand, when it exceeds 0.6, the compatibility of both resins is poor, the transparency of the resin composition is poor, the mechanical strength is impaired, and the blocking resistance is impaired. The heat of fusion of the polyester resin B is not particularly limited, but is preferably 4 cal / g or less from the viewpoint of transparency.

The polyester resin A and the polyester resin B can be obtained by subjecting an acid component and an alcohol component to a polycondensation reaction by a conventional method after direct esterification reaction or transesterification reaction (copolymerization). Polymerized polyester resin is included).

As the acid component constituting the polyester resin A and the polyester resin B, there are aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, succinic acid, adipic acid and 1,2-dodecanedicarboxylic acid. , Dimer acid, and other aliphatic dicarboxylic acids, and alcohol components include diols such as ethylene glycol, 1,2-propanediol, 1,4-butanediol, polyethylene glycol, cyclohexanedimethanol, and bisphenol A. To be As the alcohol component, malic acid, ε-caprolactone, oxyacids such as paraoxybenzoic acid, or derivatives thereof can also be used together. Other polymerization components can be used as long as they do not deviate from the above characteristic values. In addition, a component having a functional group such as a carboxylic acid ester, an acid chloride, or an oxirane ring which produces a residue corresponding to the above component by the reaction may be used.

In order to develop sufficient strength, the polyester resin A and the polyester resin B preferably have an intrinsic viscosity (IV) of 0.5 or more as a measure of the molecular weight. Here, the intrinsic viscosity is determined by measuring at 20 ° C. in a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio).

The polyester resin A and the polyester resin B may be mixed by dry-blending the resin during extrusion molding, or may be mixed in an extruder by using a feed hopper. Alternatively, it may be melt-kneaded and fed by using a biaxial kneader or an extruder before molding, or may be cooled and fed as pellets or the like.

The mixing of polyester resin A and polyester resin B is higher than the melting points of both resins to be used, and the melt viscosity ratio η A / η B of both resins is 0.1 to 10.0, more preferably 0.3 to 3 It is preferable to carry out at a temperature of 0.3. Further, since the thermal decomposition of the polyester is promoted at a high temperature, the mixing is preferably performed at 320 ° C. or lower.

When the melt-kneading is carried out at a high temperature for a long time, transesterification between the two resins is promoted, the crystallinity of the polyester resin A is impaired, and the polyester resin composition exhibits blocking properties. It is not preferable. Therefore, the residence time during kneading needs to be within a range that does not impair the characteristics of the resin. At this time, other resins, pigments, processing aids such as lubricants, etc. may be blended as long as the resin properties are not impaired.

The extrusion molding can be carried out by a generally used apparatus in which an extruder and an appropriate die such as a T die in the case of forming a film are combined. When cooled in extrusion molding, if the temperature is gradually cooled from the temperature falling crystallization temperature (Tcc) of the polyester resin B or higher, crystals may grow and the transparency may be lost.
The polyester resin has a temperature drop crystallization temperature (Tc
It is preferable to provide a cooling device so as to have c) or to be rapidly cooled to the temperature lowering crystallization temperature (Tcc) or lower.

If necessary, the polyester resin composition of the present invention may be extrusion laminated on a substrate such as paper, metal or other resin, or a transparent substrate may be used for at least one of a plurality of substrates. It may be laminated between. Further, the present polyester resin composition can be improved in mechanical properties such as breaking strength by stretching, and the molded product may be stretched continuously with extrusion molding.

[0025]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. Reference Example (Production of Polyesters a, b, c, d, and e) Using two or more kinds of various acid components shown in Table 1 and one or more kinds of alcohol components, while stirring under a nitrogen atmosphere, 24
The esterification reaction is carried out at 5 ° C until the acid value becomes 100 equivalent / ton or less, and then 0.05 parts of tetrabutyl titanate is added as a catalyst, and the polycondensation reaction is carried out by gradually reducing the pressure to 0.2 mmHg. , Polyesters a, b, c in Table 1
d and e were obtained. Table 2 shows the characteristic values of the obtained copolyester.

[0026]

[Table 1]

[0027]

[Table 2]

Example 1 70 parts by weight of polyester d as polyester resin A and 30 parts by weight of polyester b as polyester resin B were prepared and melt-mixed using a twin-screw extruder to obtain a polyester composition, which was uniaxially extruded. It was supplied to the machine and a sheet having a thickness of 1 mm was formed using a T-die.

Example 2 95 parts by weight of polyester e as polyester resin A and 5 parts by weight of polyester a as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in example 1.

Example 3 80 parts by weight of polyester e as polyester resin A and 20 parts by weight of polyester a as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in example 1.

Example 4 50 parts by weight of polyester d as polyester resin A and 50 parts by weight of polyester b as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in Example 1.

Example 5 20 parts by weight of polyester d as polyester resin A and 80 parts by weight of polyester c as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in example 1.

Comparative Example 1 100 parts by weight of polyester c was treated in the same manner as in Example 1 to obtain a sheet having a thickness of 1 mm.

Comparative Example 2 100 parts by weight of polyester e were processed in the same manner as in Example 1 to obtain a sheet having a thickness of 1 mm.

Comparative Example 3 80 parts by weight of polyester d as polyester resin A and 20 parts by weight of polyester a as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in Example 1.

Comparative Example 4 20 parts by weight of polyester e as polyester resin A and 80 parts by weight of polyester c as polyester resin B were prepared and dry blended to obtain a sheet having a thickness of 1 mm in the same manner as in Example 1.

Table 3 shows the transparency, elongation, elastic modulus and blocking resistance of each of the obtained sheets. The transparency is
It was judged visually. In addition, the blocking resistance is the situation when two sheets are stacked, a pressure of 1 kg / cm ² is applied in an atmosphere of 80 ° C., they are held for 3 hours, then they are cooled to room temperature with the pressure applied and peeled off. Was visually determined.

[0038]

[Table 3]

As is clear from Table 3, the sheets of Examples 1 to 5 were excellent in all of transparency, elongation, elastic modulus, and blocking resistance, but the sheets of Comparative Examples 1 to 4 were excellent. Was inferior in at least one of transparency, elongation, elastic modulus and blocking resistance.

[0040]

As is apparent from the above description, the present invention is a polyester resin composition capable of obtaining a molded article which is excellent in flexibility, transparency and blocking resistance only by extrusion molding. It is possible to obtain things.

Claims (1)

[Claims] 1. A crystalline polyester resin A10 having a heat of fusion of 4 cal / g or more and a glass transition temperature of 30 ° C. or less.
To 95% by weight and 90% to 5% by weight of a polyester resin B having a solubility index difference of 0.2 to 0.6 between the polyester resin A and the polyester resin A, and a polyester resin composition for extrusion molding. .