KR900006302B1 - Polyester resin composition - Google Patents

Abstract

Polyester resin compsn. having good moulding properties is improved of the crystalization velocity by, in polyethylene terephthalate resin having 0.4-1.0 dl/gr of inherent viscosity, (i) adding 0.05-30 wt.% of copolyester whose repeating unit mole ratio is 20/80-80/20 of the cpd. of formula (I)/ the cpd. of formula (II) (m=2 or 4, n= 1- 100); (ii) adding 0.1-15 wt.% of inorg, filler selected from talc, titaninm dioxide, calcium carbonate, kaoline, mica etc.; (iii) adding 0.1-15 wt.% of lubricanting agent selected from sodium stearate, magnesium steararate neopentyl glycol dibenzoate; and (iv) adding 5- 50 wt.% of glass single fiber and 5-30 wt.% of bromic flame retardant to give stiffness and flame retardancy.

Description

Composition of polyester resin

The present invention relates to a composition of a polyester resin widely used as a molding material, in particular a polyethylene terephthalate (hereinafter referred to as "PET") resin having high crystallinity, excellent moldability and dimensional stability suitable as a low temperature molding material. More specifically, the present invention relates to a PET resin composition which exhibits excellent releasability when molded at a low molding temperature of 100 ° C. or less and at the same time has excellent surface properties and physical properties.

In general, PET is inherently excellent in heat resistance, chemical resistance, mechanical properties and electrical properties, and is widely used for industrial applications such as fibers and films. However, when PET is used in a field which requires crystallinity such as plastic by making a molding, many problems arise due to the special crystallization behavior of the resin in moldability.

That is, PET is originally a crystalline polymer, but due to the high secondary transition temperature of the resin, when it is molded at a low molding temperature of less than 100 ° C, which is a general mold temperature, for use as a general thermoplastic resin, the shape and stability of the molded article deteriorate significantly and are long in the mold. It requires residence time and is poorly formed, and moldings have many defects such as sink marks and streaks.

Therefore, in order to eliminate these defects, the crystallization start temperature must be moved to a lower side and the crystallization rate must be increased so that the crystallization reaches the molding depth.

The use of inorganic materials such as talc, titanium dioxide, mica and magnesium oxide to improve the crystallization rate at low temperature molding is described in US Pat. Nos. 3,089,75,357,593, etc., US Pat. Nos. 4276208, 4215032, 4141882, Korean Patent Publication Nos. 83-856, 83-973 and the like describe the addition of an epoxy-based compound as a solidification accelerator for organic matter. In addition, US Patent No. 4366273, UK Patent No. 2075301, Korean Patent Publication No. 81-1801, and the like are known compositions containing a hydrocarbon-based metal salt or an unsaturated hydrocarbon-based polymer metal salt containing a carboxyl group.

However, when inorganic materials are used, they have different effects as nucleation agents depending on their particle size distribution or uniform dispersibility, and even when the amount of addition is increased, they do not show satisfactory effects.

In particular, it is difficult to shift the crystallization start temperature to a lower side and the crystallization of the molding surface layer formed in the low temperature mold is very bad. As an organic crystallization accelerator, physical properties are not maintained in the case of an epoxy compound, and moldability is deteriorated when a metal salt of a hydrocarbon polymer is used.

The present invention is to solve the above-mentioned shortcomings, the object of the present invention is to provide a PET composition having a high crystallization rate, high degree of crystallization, excellent releasability and surface state as well as physical properties during low-temperature molding.

In addition, the present invention is a polyethylene terephthalate resin having a molecular weight of 0.4 ~ 1.0dl / gr (measured at 25 ℃ dissolved 0.5% by weight of polymer in a mixed solution of phenol / tetrachloroethane = 1% by weight) and Represented by the following general formula:

Where m = 2 or 4, n = 1-100

Repetition of compound (II) / (I) in order to add 0.05 to 30% by weight of high polyester copolymerized from (II) compound / (I) compound repeating unit from 20/80 to 80/20 When the molar ratio of the unit is out of the range of 20/80 to 80/20, the reaction of the high polyester is unstable, and thus the crystallization rate does not improve even if the unstable high pulley is added. As the inorganic filler, talc, titanium dioxide, calcium carbonate, kaolin, and the like are added, and as a lubricant, sodium stearate, magnesium stearate, neopentyl glycol dibenzoate, and the like are used to improve the crystallization rate of polyester. There is a characteristic.

The compounds may be added in the molten state immediately after the polymerization of the polyester, or may be added in the process of reinforcing the glass fiber to improve the physical properties of the polyester, or compounding to impart flame retardancy.

In order to improve the physical properties of the resin composition of the present invention may be used by reinforcing fiber reinforcing agents such as short glass fiber, carbon fiber, Kevlar fiber, and bromine or chlorine flame retardant may be added to impart flame retardancy, It is preferable to use a fiber reinforcing agent treated with silane or borane in order to improve the adhesion with the polymer.

In addition, the coloring agent antioxidant, mold release agent, etc. which are used for the general polymer can also be added.

The molded article obtained from the composition of the present invention is sufficiently crystallized even under general molding conditions, and the molded article has excellent dimensional stability and mechanical properties even in the presence of heat.

Therefore, the composition of the present invention can be widely used in the molding of various molded parts, sheet-like articles, tubular articles, laminates, containers and the like, and is most suitable for molding of electric, electronic and automotive parts in consideration of excellent electrical properties.

When describing an embodiment of the present invention, the addition amount means weight% unless otherwise indicated, and the molding of the test piece and the evaluation of the molded product were performed according to the following method.

(1) Polymerization Reaction of Polymer

A 5ι stainless steel stil reactor with stirring and vacuum was used.

(2) mixing of additives of polymers

The polymer and the additive are automatically added to the compounder and mixed according to the composition ratio. The cylinder temperature is 260-280 ° C. and the mixture is cut into chips through a cooling bath.

(3) forming the test piece

① drying of chips

It is dried in a dehumidifying dryer at 160 ° C. for 4 hours and dried to have a moisture content of 0.01 wt% or less.

② Formation of Test Piece

It is molded into a test piece by a desired injection machine, and the molding conditions are: cylinder temperature: 280 ° C, molding temperature: 85 to 110 ° C, injection holding time: 15 seconds, cooling time: 15 seconds, injection pressure: 300 to 600 Kg / Cm². .

(4) Surface characteristics of moldings

Visually observe the external appearance of the test piece from the mold after injection molding

(5) mold release property

When the injection test was performed 50 times, the number of times the test piece fell without sticking to the mold was measured.

(6) shrinkage of moldings

The shrinkage ratio of the longitudinal length (ι) of the test piece (127 x 12.7 x 3.2 mm) exiting the mold after molding is measured.

Where ₀ is the length of the mold

(7) evaluation of crystallization rate

Tch is the crystallization temperature that appears when heating up to 280 ° C at 20 ° C / min using differential scanning calorimetry analysis (DSC). The difference is called ΔTc and the relative comparison is made to evaluate the crystallization rate.

The larger the range of ΔTc, the faster the crystallization rate. Hereinafter, the present invention will be described in detail with reference to the following Examples. The present invention will be described with reference to examples.

Example 1

98.5 grams of polyethylene terephthalate resin having an intrinsic viscosity of 0.65 dl / gr and 0.5 gram of copolyester (II compound: I compound is 50:50), 0.3 g of sodium stearate, 0.5 grams of talc, neopentyl 0.2 grams of glycol dibenzoate was continuously mixed, cooled, and pelated in a compound, and then the degree of crystallinity was evaluated by a differential scanning thermal analyzer.

Example 2

Except for using only the copolyester (mole ratio of II compound / I compound is 65:35) of the additive of the present invention and changing the addition amount was carried out in the same manner as in Example 1.

Example 3

Except that the copolyester (II compound: I compound molar ratio of 50:50) of the additive of the present invention was used and the amount of addition was changed, the same procedure as in Example 1 was carried out.

Example 4

Except that the copolyester (II compound: I compound molar ratio of 75: 25) of the additive of the present invention was used and the addition amount was changed, it was carried out in the same manner as in Example 1.

Example 5

The same procedure as in Example 1 was carried out except that only the copolyester (the molar ratio of the II compound: I compound was 50:50), which was an additive of the present invention, was changed.

Comparative Examples 1 to 6

It was carried out in the same manner as in Example 1 using only additives other than copolyesters of the present invention.

[Examples 6-9]

In order to enhance the physical properties, 30% by weight of 3 mm AASHI Fiber Glass surface-treated with a silane compound was added, and decabromo biphenyl oxide was used as a brominated flame retardant to impart flame retardancy. After mixing and pelletizing together in a compounder, the test piece was molded by an injection molding machine to evaluate the crystallization rate and formability.

Comparative Examples 7 to 10

The copolyester of the present invention was not used and was carried out in the same manner as in Examples 6-9.

The above evaluation results are shown in Table 1 and Table 2.

TABLE 1

TABLE 2

1) G / F: short glass fiber

2) FR: Flame Retardant

Claims (1)

Copolyester copolymerized with a polyethylene terephthalate resin having an intrinsic viscosity of 0.4-1.0 dl / gr, in which the molar ratio of (i) the compound / (I) compound repeating unit represented by the following formula (i) is from 20/80 to 80/20 Add 0.05% to 30% by weight,

Where m = 2 or 4 and n = 1-100.

(ii) 0.1 to 15% by weight of talc, titanium dioxide, calcium carbonate, kaolin, mica, etc. are added as inorganic fillers, and (iii) sodium stearate, magnesium stearate neopentyl glycol dibenzoate as lubricant. 0.1 wt% -15 wt% is added, and (iv) 5-50 wt% glass short fibers and 5-30 wt% bromine-based flame retardant are added to enhance physical properties and impart flame retardancy. Polyester resin composition with excellent moldability.