JP2000129106A - Thermoplastic polyester-based resin composition and molded product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of providing a packaging material excellent in impact resistance, processing property, sealing property and taste-preserving property by including a thermoplastic aromatic polyester and a specific thermoplastic soft polyester. SOLUTION: This thermoplastic polyester-based resin composition contains at least (A) a thermoplastic aromatic polyester (preferably a polyethylene terephthalate, a polyethylene naphthalate, etc.), and (B) a thermoplastic soft polyester having <=0 deg.C glass transition temperature and <=15 (cal/g) latent heat of its crystal melting, and the component B is dispersed in <=2.0 μm mean particle diameter. It is preferable that the ratio of the components A to B in wt.pts. is (99:1)-(50:50). The composition can be applied as an innermost layer of a bag-shaped package by processing it to a sheet state, and used suitable as a food container since it is excellent in taste-preserving property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyester resin composition capable of producing a molded article having improved impact resistance and excellent processability, sealability and flavor, and a molded article thereof.

[0002]

2. Description of the Related Art Thermoplastic aromatic polyesters such as polyethylene terephthalate have excellent physical properties (mechanical strength,
It is processed into stretched films and containers from the viewpoint of moldability and content preservability, and is widely applied as a packaging material. further,
Since the thermoplastic aromatic polyester has low odor and low adsorptivity, it has little effect on the taste of the contents when used as the innermost layer of a food container that comes into contact with the contents. Superior in taste preservation as compared with the base resin. Due to these properties, polyethylene terephthalate is widely applied to stretched PET bottles for beverages and the like. In recent years, not only polyethylene terephthalate but also thermoplastic aromatic polyesters such as polyethylene naphthalate, which is superior in heat resistance and ultraviolet absorbing ability, and polybutylene terephthalate, which has excellent processability and sealability, compared to polyethylene terephthalate, are used as packaging materials. Its application has been widely studied.

However, when these thermoplastic aromatic polyesters are applied to an unstretched polyester sheet that can be heat-sealed as the innermost layer of a bag package formed by laminating, they are dropped due to insufficient impact strength. However, there is a problem that the bag is easily damaged.

Thus, the impact resistance of the film can be improved by blending a polyolefin-based elastomer with a thermoplastic aromatic polyester, but the taste preservation of the contents is impaired due to the inclusion of the olefin-based material. It is not preferred. In addition, a polyester heat sealing material having excellent taste preservation properties, and a polyalkylene glycol introduced (Japanese Patent Application Laid-Open No. 7-216067) or a copolymerized polyester blend (Japanese Patent Application Laid-Open No. However, these inventions do not sufficiently improve the impact resistance, and in particular, the impact resistance in a low-temperature atmosphere such as a refrigeration temperature is insufficient. There was a problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and has excellent impact resistance.
In addition, the present invention relates to a thermoplastic polyester-based resin composition capable of producing a packaging material having excellent processability, sealability, and taste preservability, and a molded article using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted studies for overcoming the above problems, and as a result, have completed the present invention.

That is, the invention according to claim 1 is characterized in that the thermoplastic aromatic polyester has a glass transition point of 0 ° C. or less,
A thermoplastic polyester comprising at least a thermoplastic soft polyester having a heat of crystal fusion of 15 (cal / g) or less, and wherein the thermoplastic soft polyester is dispersed with an average particle diameter of 2.0 μm or less. It is a resin composition.

[0008] In the present invention, the thermoplastic soft polyester means a thermoplastic polyester having a glass transition point lower than room temperature.

When the glass transition point of the thermoplastic soft polyester is 0 ° C. or higher, the impact resistance of the polyester resin composition at a low temperature becomes insufficient. The glass transition point is preferably -2.
Those having a temperature of 0 ° C. or less are used. In the present invention,
The glass transition point was measured by differential thermal scanning calorimetry.

Further, the heat of crystal fusion is 15 (cal / g).
A larger one is not preferred because the impact resistance of the polyester resin composition becomes insufficient. Preferably it is 10 (cal / g) or less. In the present invention, the heat of crystal fusion was measured by differential scanning calorimetry in the same manner as the glass transition point.

Further, when the average particle size of the thermoplastic soft polyester to be blended is larger than 2.0 μm, the impact resistance of the polyester resin composition becomes insufficient. Here, the average particle diameter indicates the particle diameter of the thermoplastic soft polyester dispersed in the thermoplastic polyester-based resin composition, and refers to a value obtained by averaging. In the present invention, the average particle size was determined by observing with a scanning electron microscope.

According to a second aspect of the present invention, the ratio by weight of the thermoplastic aromatic polyester to the thermoplastic soft polyester is blended in the range of 99: 1 to 50:50. 2. The thermoplastic polyester resin composition according to item 1. In the present invention, the ratio of the parts by weight of the thermoplastic aromatic polyester to the thermoplastic soft polyester is preferably in the range of 99: 1 to 50:50. If the ratio by weight of the thermoplastic soft polyester is less than 1, the effect of improving the impact resistance is hardly obtained, and if it is more than 50, the taste preservability deteriorates, which is not preferable. The ratio by weight of the thermoplastic aromatic polyester to the thermoplastic soft polyester is preferably from 97: 3 to 60:40. Especially preferably, it is 95: 5 to 65:35.

The invention according to claim 3 is characterized in that the thermoplastic aromatic polyester is polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate. It is a resin composition.

According to a fourth aspect of the present invention, the thermoplastic soft polyester is an aliphatic polyester or an aliphatic polyester carbonate.
4. The thermoplastic polyester-based resin composition according to any one of Items 1 to 3.

[0015] The invention according to claim 5 provides the invention according to claims 1 to 4.
A molded article obtained by molding any of the thermoplastic polyester-based resin compositions described in (1).

[0016]

Embodiments of the present invention will be described below in detail.

As the thermoplastic aromatic polyester of the present invention, a thermoplastic aromatic polyester comprising a structural unit derived from a dicarboxylic acid and a diol can be widely used. Among them, polyethylene terephthalate, polyethylene naphthalate, and polybutylene are particularly preferred. Terephthalate is preferably used. However, it is not limited to these thermoplastic aromatic polyesters.

Polyethylene terephthalate is composed of structural units derived from terephthalic acid and ethylene glycol, and may be a dicarboxylic acid component other than terephthalic acid, such as isophthalic acid, adipic acid and sebacic acid.
Diethylene glycol other than ethylene glycol, 1,
A copolymer containing a diol component such as 4-cyclohexanediol may be used.

Similarly, in polyethylene naphthalate composed of structural units derived from 2,6-naphthalenedicarboxylic acid and ethylene glycol, and polybutylene terephthalate composed of structural units derived from terephthalic acid and butylene glycol, other dicarboxylic acids are also used. It may be a copolymer containing a component or a diol component.

Further, two or more kinds of these thermoplastic aromatic polyesters may be used as a mixture, or a small amount of another polymer may be blended if necessary.

In the present invention, the thermoplastic soft polyester blended with the above-mentioned thermoplastic aromatic polyester has a glass transition point of 0 ° C. or less and a heat of crystal fusion of 15 (cal / cm).
g) Any of the following can be used. In particular,
Aliphatic polyesters and aliphatic polyester carbonates can be suitably used, and specific examples thereof include polybutylene succinate, polybutylene succinate / adipate, and polyester carbonate, but are not limited thereto. If necessary, two or more of these may be used. In addition, a small amount of another polymer may be blended with these thermoplastic soft polyesters as needed.

In the present invention, the polyester resin composition is adjusted by a suitable melt-kneading apparatus, for example, a batch-type kneading apparatus such as a Brabender mixer or a Banbury mixer, a continuous kneading apparatus such as a single-screw extruder, or a twin-screw extruder. The thermoplastic aromatic polyester and the thermoplastic soft polyester can be melt-mixed using the following process.Then, if necessary, the melt can be formed into a film using a T-die, or once the melt blend can be formed into pellets. However, it is also possible to use this as a material.

The polyester resin composition of the present invention can be used to obtain a molded article by a molding method such as injection molding, extrusion molding, stretch blow molding or the like, similarly to a general thermoplastic polyester resin. It is not limited to these molding methods.

In the present invention, a thermoplastic aromatic polyester having a glass transition point of 0 ° C. or less and a heat of crystal fusion of 15 ° C.
(Cal / g) or less, and the thermoplastic soft polyester is dispersed with an average particle size of 2.0 μm or less. High impact resistance. Good flavor properties can be obtained by using a thermoplastic soft polyester having the same skeleton as a blend component with respect to the thermoplastic aromatic polyester.

[0025]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 80 parts by weight of a polyethylene terephthalate resin (RT543C, manufactured by Nippon Unipet, hereinafter abbreviated as PET) as a thermoplastic aromatic polyester resin, and polybutylene succinate / adipate as a thermoplastic soft polyester (Showa Koto) Molecule, Bionore #
3001, MI = 2, glass transition point = −45 ° C., heat of crystal fusion = 8.4 cal / g, hereinafter abbreviated as PBSA) 20
The mixture of parts by weight of the raw material pellets was sufficiently melt-kneaded at 265 ° C. using a twin-screw extruder to obtain a thermoplastic polyester resin composition of the present invention. Further, this polyester resin was extruded into a pellet shape. At this time, the average particle size of PBSA was 1.1 μm. Next, this was supplied to a single screw extruder, and a sheet (hereinafter abbreviated as a sealant) having a thickness of 70 μm extruded from a T-die at 265 ° C. was produced. Thereafter, stretched PET (thickness: 12 μm) / Al (thickness: 9 μm) / sealant (thickness: 70 μm) was laminated in order from the outermost layer to the innermost layer using the obtained sealant. Using this laminated sheet, distilled water was filled in as a content, and three-way thermocompression bonding was performed.
m pouches were prepared. According to the above method, the pouch containing the distilled water thus produced is dropped from a height of 120 cm onto a concrete floor (room temperature 5 ° C.), and the number of drops until the bag is broken by repeating this is measured. evaluated. After storing the pouch at 90 ° C. for 5 hours, it was stored at room temperature for 3 days, and the taste change of distilled water in the contents was evaluated by a sensory test.

Example 2 The thermoplastic polyester resin composition of the present invention was prepared in the same manner as in Example 1 except that 60 parts by weight of PET was used as the thermoplastic aromatic polyester and 40 parts by weight of PBSA was used as the thermoplastic soft polyester. Was obtained (at this time, the average particle size was 1.7 μm) to prepare a pouch. Further, the pouch was evaluated for a bag drop test and a change in taste.

<Example 3> The thermoplastic polyester resin composition of the present invention was prepared in the same manner as in Example 1 except that 90 parts by weight of PET was used as the thermoplastic aromatic polyester and 10 parts by weight of PBSA was used as the thermoplastic soft polyester. (The average particle diameter at this time was 0.8 μm) to prepare a pouch. Further, the pouch was evaluated for a bag drop test and a change in taste.

Example 4 80 parts by weight of PET as a thermoplastic aromatic polyester and polyester carbonate (polybutylene succinate, dimethyl succinate, 1,4-butanediol, and diethyl carbonate as raw materials) were used as a thermoplastic soft polyester by condensation polymerization. Synthesis, containing 20 mol% of carbonate, glass transition point = -42 ° C, heat of crystal fusion = 11.8 cal / g, abbreviated as PEC) 20
The same operation as in Example 1 was performed except that the parts by weight were used to obtain a thermoplastic polyester resin composition of the present invention (the average particle diameter at this time was 1.0 μm), and a pouch was produced. Further, the pouch was evaluated for a bag drop test and a change in taste.

Example 5 As a thermoplastic aromatic polyester, polyethylene naphthalate resin (Nippon Kokan, N
XP-1500 (hereinafter abbreviated as PEN) was performed in the same manner as in Example 1 except that 70 parts by weight of PBSA and 30 parts by weight of PBSA as a thermoplastic soft polyester were used to obtain a thermoplastic polyester resin composition of the present invention. The average particle size at the time was 1.2 μm), and a pouch was produced. Further, the pouch was evaluated for a bag drop test and a change in taste.

Example 6 As a thermoplastic aromatic polyester, a polybutylene terephthalate resin (manufactured by Mitsubishi Chemical Corporation;
NOVADUR5010 (hereinafter abbreviated as PBT) was performed in the same manner as in Example 1, except that 80 parts by weight of PBSA and 20 parts by weight of PBSA as a thermoplastic soft polyester were used to obtain a thermoplastic polyester resin composition of the present invention (at this time). An average particle diameter was 0.7 μm), and a pouch was produced. further,
This pouch was evaluated for a bag drop test and a change in taste.

<Comparative Example 1> 70 parts by weight of PET as a thermoplastic aromatic polyester and polybutylene succinate / adipate as a thermoplastic soft polyester (manufactured by Showa Kobunshi, Bionole # 3020, MI = 25, glass transition point = -45 ° C.) The same operation as in Example 1 was carried out except that 30 parts by weight of heat of crystal melting = 8.8 cal / g (hereinafter abbreviated as PBSA) was used (the average particle diameter at this time was 2.2 µm).
m), a pouch was prepared. Further, the pouch was evaluated for a bag drop test and a change in taste.

Comparative Example 2 80 parts by weight of PET as a thermoplastic aromatic polyester, and polybutylene succinate as a thermoplastic soft polyester (manufactured by Showa Kogyo Co., Ltd., Bionole # 1001, MI = 2, glass transition point = −32 ° C.)
The same operation as in Example 1 was performed except that 20 parts by weight of the heat of crystal fusion = 16.3 cal / g (hereinafter abbreviated as PBS) (the average particle diameter at this time was 0.8 μm) to prepare a pouch. Further, the pouch was evaluated for a bag drop test and a change in taste.

<Comparative Example 3> A sealant was prepared using only polypropylene (manufactured by Toyobo Co., Ltd., P1146, hereinafter abbreviated as PP). A pouch was prepared in the same manner as in Example 1. The taste change was evaluated.

The dropping bag test and the change in taste of water evaluated in the above Examples and Comparative Examples are shown in Table 1. (Note 1) Drop bag test (number of drops): Number of drops before breaking the bag (Note 2) Change in taste of water ◎: Good without change ○: Very little change in taste ×: Off-flavor or odor

[0036]

[Table 1]

[0037]

According to the first aspect of the present invention, in addition to the inherent properties of thermoplastic aromatic polyester such as mechanical strength, moldability, and content preservation, a sheet excellent in taste preservation and impact resistance can be obtained. A thermoplastic polyester resin composition that can be produced was obtained. In addition, good flavor properties can be obtained by blending a thermoplastic soft polyester having the same skeleton with a thermoplastic aromatic polyester. In addition, the polyester resin composition has a wide range of applications for processing and has excellent sealing properties.

According to the second aspect of the invention, by specifying the blending ratio of the thermoplastic aromatic polyester and the thermoplastic soft polyester, a sufficient taste preserving property and impact resistance can be obtained.

According to the third aspect of the present invention, a particularly preferable thermoplastic aromatic polyester is specified.

According to the fourth aspect of the present invention, a particularly suitable thermoplastic soft polyester is specified.

According to the fifth aspect of the present invention, this thermoplastic polyester resin composition can be formed by a molding method such as injection molding, extrusion molding, stretch blow molding or the like, similarly to a general thermoplastic polyester resin. Thus, various molded products can be obtained, and particularly, processed into a sheet shape and applied as the innermost layer of a bag package. Furthermore, since it is excellent in taste preservation, it can be suitably used for food containers.

Claims (5)

[Claims] (1) a thermoplastic aromatic polyester and at least a thermoplastic soft polyester having a glass transition point of 0 ° C. or less and a heat of crystal fusion of 15 (cal / g) or less, and the thermoplastic soft polyester is an average A thermoplastic polyester-based resin composition characterized by being dispersed with a particle size of 2.0 μm or less. 2. The composition of claim 1, wherein the ratio by weight of the thermoplastic aromatic polyester to the thermoplastic soft polyester is 99: 1 to 50:50.
2. A blend according to claim 1, wherein
The thermoplastic polyester-based resin composition according to the above. 3. The thermoplastic polyester resin composition according to claim 1, wherein the thermoplastic aromatic polyester is polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate. 4. The thermoplastic polyester resin composition according to claim 1, wherein the thermoplastic soft polyester is an aliphatic polyester or an aliphatic polyester carbonate. 5. A molded article obtained by molding any one of the thermoplastic polyester resin compositions according to claim 1.