JPH10316845A - Polyester-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, excellent in antistatic properties, good in transparency and useful for films, etc., by compounding a thermoplastic polyester with a polyoxyalkylene glycol and a specific basic metallic salt. SOLUTION: This composition is obtained by compounding (A) 100 pts.wt. thermoplastic polyester with (B) 1-30 pts.wt. polyoxyalkylene glycol and (C) a basic metallic salt of group I or II of the periodic table of metals so as to contain the basic metal in an amount of 3-50 mol.% based on the structural unit of the component B. The component A is preferably polyethylene terephthalate or polyethylene naphthalate and the average molecular weight of the component B is preferably not higher than 1,000. The component C is preferably a lithium salt, a sodium salt or a potassium salt.

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 having excellent antistatic properties and, if necessary, capable of producing a molded article having good transparency.

[0002]

2. Description of the Related Art Thermoplastic polyesters such as polyethylene terephthalate are processed into films and bottles due to their excellent physical properties (mechanical strength, moldability, content preservability), and are widely applied as packaging materials. However, the polyester resin has a problem that it is easily electrostatically charged, and dust or the like adheres to the surface of the molded product, and the appearance is easily deteriorated.

[0003] In order to eliminate such an obstacle due to charging, antistatic agents such as surfactants have been generally used. Antistatic agents such as surfactants exhibit an antistatic effect by utilizing the transfer of electric charge due to absorption of moisture in the hydrophilic field air in the antistatic agent, and such an antistatic agent is It is applied to form an antistatic layer on the surface of a molded article made of a polyester resin such as a film, or is previously blended in a polyester resin, and is applied to a method of forming this into a molded article.

However, in the method of coating on the surface of a molded article, the antistatic layer on the surface is easily peeled off, so that the durability of the antistatic effect is poor, and a uniform surface coating is formed on various molded articles having a complicated surface shape. In addition, there is a problem that it is difficult to perform the process, and a separate process for applying the antistatic agent is required, so that the cost increases.

[0005] Further, in the method of preliminarily blending in a polyester resin, the antistatic agent used is an ionic antistatic agent such as an alkyl sulfonic acid salt or a quaternary ammonium salt, and a polyether or a polyhydric alcohol. And non-ionic antistatic agents. The ionic antistatic agent has a relatively high antistatic effect and requires only a small amount of addition, but is inferior in thermal stability, and thus has a problem that it is easily decomposed and colored during processing and molding of the polyester resin. In addition, nonionic antistatic agents have relatively good thermal stability, but their antistatic effect is slightly inferior, so it is necessary to add a relatively large amount in order to obtain a sufficient antistatic effect. There is a problem that the property is impaired.

As described above, the surface coating type antistatic agent causes the antistatic layer to be peeled off, so that the effect of the antistatic layer is poor. Even if the antistatic layer formed on the surface layer of the molded article is lost for some reason, the antistatic agent exudes from the inside of the molded article to the surface of the molded article, and the antistatic layer can be formed again. As described above, the kneading type antistatic agent is excellent in persistence of the antistatic effect, but generally, when added to a resin having a glass transition point higher than room temperature, such as a polyester resin, the antistatic agent in the resin is used. Has a low diffusion rate and does not easily exude to the surface, and a sufficient antistatic effect cannot be obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic polyester resin composition capable of producing a molded article having excellent antistatic properties and excellent transparency.

[0008]

Means for Solving the Problems The present inventors have solved the above-mentioned problems by blending a polyoxyalkylene glycol and a basic metal salt of Group 1 or 2 of the periodic table with a thermoplastic polyester. did.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic polyester used in the present invention is not particularly limited, and those widely known as thermoplastic polyesters comprising structural units derived from dicarboxylic acids and diols can be used. However, a biodegradable polyester made of polyethylene terephthalate, polyethylene naphthalate, or a polymer or copolymer of oxyacid is particularly preferable.

Polyethylene terephthalate is composed of structural units derived from terephthalic acid and ethylene glycol, and includes dicarboxylic acid components such as isophthalic acid other than terephthalic acid, adipic acid and sebacic acid, diethylene glycol other than ethylene glycol, and 1,4-cyclohexanediol. It may be a copolymer containing a diol component. Similarly, a polyethylene naphthalate comprising a structural unit derived from 2,6-naphthalenedicarboxylic acid and ethylene glycol may be a copolymer containing other structural units. A biodegradable polyester made of a polymer or copolymer of an oxyacid may contain structural units other than the oxyacid. In addition, a small amount of another polymer may be blended in the thermoplastic polyester as needed.

In the present invention, as the polyoxyalkylene glycol added to the thermoplastic polyester, polyethylene glycol, polypropylene glycol, or a polyoxyalkylene glycol comprising oxyethylene units and oxypropylene units can be used. Such a polyoxyalkylene glycol may be any as long as it is mainly composed of an oxyethylene unit or an oxypropylene unit, and may have a structure in which a terminal is bonded to another component as needed. It is desirable that the average molecular weight of the polyoxyalkylene glycol does not exceed 1,000. If the average molecular weight exceeds 1,000, the transparency is remarkably reduced when added to the thermoplastic polyester.

In the present invention, the basic metal salt to be added to the thermoplastic polyester together with the polyoxyalkylene glycol is a salt of a basic metal belonging to Group 1 or 2 of the periodic table, preferably a lithium salt, Sodium or potassium salts are used.

The amount of the polyoxyalkylene glycol added in the present invention is preferably 1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polyester.
If the amount is less than 1 part by weight, almost no antistatic effect can be obtained, and if it is more than 30 parts by weight, the moldability and product properties are remarkably reduced. The addition amount of the polyoxyalkylene glycol is preferably 3 parts by weight to 15 parts by weight based on 100 parts by weight of the thermoplastic polyester.

The amount of the basic metal salt added to the thermoplastic polyester together with the polyoxyalkylene glycol may be such that the basic metal is 3 to 50 mol% with respect to the polyoxyalkylene glycol structural unit.
If the amount is less than this range, the antistatic effect is hardly obtained, and if it is more than this range, the physical properties of the molded article such as moldability and transparency are significantly reduced. The amount of the basic metal salt added to the thermoplastic polyester is preferably 5 to 30 mol% based on the polyoxyalkylene glycol structural unit.

In the preparation of the thermoplastic polyester resin composition of the present invention, first, a polyoxyalkylene glycol prepared by uniformly dissolving a predetermined amount of a basic metal salt in a polyoxyalkylene glycol using an appropriate solvent is mixed with a basic metal salt. To form a polyoxyalkylene glycol-basic metal salt complex. The composite is then placed in a thermoplastic polyester resin using an appropriate melt-kneading apparatus, for example, a batch-type kneading apparatus such as a Brabender mixer or a Banbury mixer, or a continuous kneading apparatus such as a single-screw extruder or a twin-screw extruder. The intended amount of the thermoplastic polyester resin composition is obtained by melt-mixing a fixed amount.

The above polyoxyalkylene glycol-
It is known that the basic metal salt complex forms a complex based on an ionic interaction with the oxygen atom in the polyoxyalkylene glycol as a metal ion in the metal portion of the basic metal salt. It shows much higher electrical conductivity than polyoxyalkylene glycol alone. Further, the basic metal salt used in the present invention generally has a very high hygroscopicity, and the polyoxyalkylene glycol-basic metal salt complex containing the same shows a high degree of hydrophilicity. An excellent antistatic effect can be obtained by using such a polyoxyalkylene glycol-basic metal salt complex having a high degree of hydrophilicity and electrical conductivity as an antistatic agent and adding it to a thermoplastic polyester resin.

[0017] The thermoplastic polyester resin composition of the present invention comprises, as in a general thermoplastic polyester resin,
It can be used for molding methods such as injection molding, extrusion molding, stretch blow molding and the like.

<Function> In the present invention, excellent antistatic properties can be obtained by blending a polyoxyalkylene glycol and a basic metal salt of Group 1 or 2 of the periodic table with a thermoplastic polyester resin. Can be. The fact that the addition of a basic metal salt of Group 1 or 2 of the periodic table provides a larger antistatic effect than when only polyoxyalkylene glycol, which is a nonionic antistatic agent, is added. Although the reason is unknown, it is considered that the added basic metal contributes to the charge transfer for suppressing the charge.

Good transparency can be obtained by selecting a polyoxyalkylene glycol having an average molecular weight of not more than 1000. This is because the lower molecular weight has better compatibility with the thermoplastic polyester resin. It is.

[0020]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. <Example 1> Polyethylene glycol having an average molecular weight of 200 (hereinafter referred to as PEG-
5 parts by weight of 200 M) and 1.2 parts by weight of lithium chloride (hereinafter abbreviated as LiCl) as a basic metal salt are added to 10 parts by weight of methanol, and the mixture is stirred at room temperature for several minutes until uniform. Then, while heating, methanol was sufficiently removed under reduced pressure to obtain a complex of polyethylene glycol and lithium chloride. Next, a polyethylene terephthalate resin (manufactured by Nippon Unipet, RT
543C (hereinafter abbreviated as PET)) to obtain 100 parts by weight of a thermoplastic polyester resin composition. The addition was carried out using a twin-screw extruder and melt-kneaded sufficiently at 265 ° C. so as to obtain a uniform composition. Using the resin composition obtained above, 100 mm × 10
A flat plate having a thickness of 0 mm and a thickness of 0.15 mm was obtained.

Example 2 A flat plate was obtained in the same manner as in Example 1 except that lithium chloride was used in an amount of 0.5 part by weight. <Example 3> A flat plate was obtained in the same manner as in Example 1 except that 1.9 parts by weight of lithium chloride was used. <Example 4> 10 parts by weight of PEG-200M and lithium trifluoromethylsulfonate (hereinafter referred to as L
A flat plate was obtained in the same manner as in Example 1 except that 8.9 parts by weight was used (abbreviated as iCF ₃ SO ₃ ). Example 5 A flat plate was obtained in the same manner as in Example 1, except that 5 parts by weight of PEG-200M and 2.3 parts by weight of sodium thiocyanate (hereinafter abbreviated as NaSCN) as a basic metal salt were used. Example 6 A flat plate was obtained in the same manner as in Example 1, except that 10 parts by weight of PEG-200M and 5.5 parts by weight of potassium thiocyanate (hereinafter abbreviated as KSCN) as a basic metal salt were used. Example 7 As a polyoxyalkylene glycol, polyethylene glycol having an average molecular weight of 600 (hereinafter referred to as PE
G-600M) A flat plate was obtained in the same manner as in Example 1 except that the amount was 5 parts by weight. <Example 8> Polyoxyrecol (hereinafter, PPG-72)
A flat plate was obtained in the same manner as in Example 1 except that 10 parts by weight was used. Example 9 A polyethylene naphthalate resin (NXP-150, manufactured by Nippon Kokan Co., Ltd.) was used as the thermoplastic polyester resin.
0, hereinafter abbreviated as PEN) to obtain a flat plate in the same manner as in Example 1. <Example 10> PEN as a thermoplastic polyester resin
And a flat plate was obtained in the same manner as in Example 1 except that sodium thiocyanate was used as the basic metal salt. <Example 11> A flat plate was obtained in the same manner as in Example 1 except that a polylactic acid resin (manufactured by Shimadzu Corporation, Lacty, hereinafter abbreviated as PLA) was used as the thermoplastic polyester resin. <Example 12> PLA as a thermoplastic polyester resin
And a flat plate was obtained in the same manner as in Example 1 except that sodium thiocyanate was used as the basic metal salt.

<Comparative Example 1> A flat plate having a size of 100 mm x 100 mm and a thickness of 0.15 mm was obtained using PET by a hot press. <Comparative Example 2> 100 m by hot press using PEN
A flat plate having a size of mx 100 mm and a thickness of 0.15 mm was obtained. <Comparative Example 3> 100 m by hot press using PLA
A flat plate having a size of mx 100 mm and a thickness of 0.15 mm was obtained. <Comparative Example 4> In Example 1, only 5 parts by weight of PEG-200M was used as a polyoxyalkylene glycol by PET.
In addition, a flat plate was obtained in the same manner as in Example 1. <Comparative Example 5> As a polyoxyalkylene glycol, polyethylene glycol having an average molecular weight of 3000 (hereinafter referred to as P
EG-3000M) A flat plate was obtained in the same manner as in Example 1 except that the amount was 5 parts by weight. The flat plates obtained in the above Examples and Comparative Examples were left under the conditions of 25 ° C. and 65% RH for 72 hours, and then the half life of the charged voltage, the surface resistivity and the transparency were evaluated. The results are shown in Table 1. The half-life of the charged voltage was measured using an honest meter (manufactured by Shishido Shokai Co., Ltd.) at an applied voltage of 10 kV. Was measured. The transparency was visually evaluated according to the following criteria.

[0023]

[Table 1]

[0024]

According to the present invention, a polyoxyalkylene glycol and a basic metal salt of Group 1 of the Periodic Table are blended with a thermoplastic polyester to provide excellent antistatic properties, and if necessary, Thus, a thermoplastic polyester resin composition capable of producing a molded article having transparency is obtained. The thermoplastic polyester resin composition obtained by the present invention can be used for various molded products, such as injection molding, extrusion molding, stretch blow molding, etc., similarly to general thermoplastic polyester resins. .
In particular, it is suitably used as a packaging material for containers and films.

Claims (6)

[Claims] 1. A thermoplastic polyester, comprising: a polyoxyalkylene glycol;
A polyester resin composition comprising a group III basic metal salt. (2) 1 to 30 parts by weight of a polyoxyalkylene glycol based on 100 parts by weight of a thermoplastic polyester;
3 to 3 per polyoxyalkylene glycol structural unit
2. The polyester resin composition according to claim 1, wherein a basic metal salt of Group 1 or 2 of the periodic table of metals is blended so as to contain 50 mol% of a basic metal. 3. The polyester resin composition according to claim 1, wherein the thermoplastic polyester is polyethylene terephthalate or polyethylene naphthalate. 4. The polyester resin composition according to claim 1, wherein the thermoplastic polyester is a biodegradable polyester comprising a polymer or copolymer of an oxyacid. 5. The polyester resin composition according to claim 1, wherein the basic metal salt of Group 1 of the periodic table is a lithium salt, a sodium salt, or a potassium salt. 6. The polyester resin composition according to claim 1, wherein the average molecular weight of the polyoxyalkylene glycol does not exceed 1,000.