JPH0578584B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester resin composition that has improved mold releasability during molding and can be molded in a short cycle over a wide mold temperature range. Thermoplastic polyesters, such as polyethylene terephthalate, have excellent mechanical properties, electrical properties, heat resistance, and chemical resistance, and are used in many industrial products as fibers and films. In this way, fiber,
When used as a film, it is usually stretched, but when it is intended to be used as an injection molded product for plastic purposes, for example, it is not stretched as described above. It is known that various problems occur in terms of molding and physical properties. In other words, polyethylene terephthalate has a low crystallization rate at low temperatures, so the mold temperature normally used when injection molding other plastics is approximately 60°C to 120°C.
Because the crystallization rate is insufficient in the temperature range of This has a fatal problem in terms of molding and physical properties, that is, it is impossible to obtain a molded product with sufficient durability. In order to improve the drawbacks of polyethylene terephthalate, that is, to increase the crystallization rate of polyethylene terephthalate in the low temperature range (below 120°C), various studies have been carried out.
Various crystal nucleating agents, crystallization promoters, and modification (copolymerization) of polyethylene terephthalate have been proposed, with considerable success. However, when the thus improved polyethylene terephthalate or its resin composition is injection molded,
At a mold temperature of 90°C or higher or 50°C or lower, relatively good mold releasability is exhibited, but at a mold temperature of 50°C to 90°C, the so-called non-ferrous properties are close to the glass transition temperature of polyethylene terephthalate or modified polyethylene terephthalate. Since it is in a stable region, it has poor releasability from the mold surface, resulting in a problem that the molding cycle becomes longer. The present inventors have conducted intensive research to solve these molding problems, that is, to obtain a thermoplastic polyester composition that exhibits excellent mold release properties even in the entire mold temperature range normally used. , arrived at the present invention. That is, the gist of the present invention is as follows. polyethylene terephthalate or at least
For 100 parts by weight of polyester having 80 mol% ethylene terephthalate repeating units, (a) ethylene-propylene copolymer,
Propylene-butadiene copolymer, ethylene-
A polyolefin copolymer selected from the group consisting of propylene-isoprene copolymer and ethylene-propylene-chloroprene copolymer, and an alicyclic carboxylic acid having a cis-type double bond in the ring or its acid anhydride. 0.1 to 10 parts by weight of a modified polyolefin copolymer to which at least one selected compound is added in an amount of 0.001 to 10 mol % based on the constituent monomers of the polyolefin copolymer, and (b) 0.1 part of a compound represented by the following general formula (). ~Ten
A polyester resin composition formed by blending parts by weight.

[Chemical formula] However, X: direct bond, alkylene group, -SO ₂
-, -S-, -O- or -CO
- R ₁ , R ₂ : Alkyl group having 5 or more carbon atoms, R ₁ , R ₂ are the same or different groups R ₃ , R ₄ : H, alkyl group or halogen, R ₃ , R ₄ are the same or different groups m, n: an integer of 1 or more In general, when a crystal nucleating agent or crystallization accelerator is added to polyethylene terephthalate or a polyester having 80 mol% or more of ethylene terephthalate repeating units (hereinafter abbreviated as PET), the PET used and the crystal nuclei The degree of crystallization varies depending on the type of agent or crystallization accelerator, but it has a high crystallization rate even when the mold temperature during molding is 120℃ or less.
A PET resin composition is obtained. However, to date, no PET resin composition has been found that fully crystallizes at a mold temperature of approximately 80°C or lower for thin-walled molded products. The reality is that only molded products can be obtained. On the other hand, the mold releasability of PET resin compositions depends on the mold temperature, and generally the mold temperature range is within the mold temperature range where the PET resin sufficiently crystallizes, for example, 90°C or higher, and the mold temperature where the PET resin hardly crystallizes. For example, when the mold temperature is below 60℃, relatively good mold release properties are often exhibited even without the addition of a mold release agent, but when the mold temperature is in between, for example from 60℃ to 90℃, the mold release properties are poor. Problems often arise. On the other hand, when a specific compound such as component (B) is further blended into a low-temperature crystalline PET resin composition in which component (A) is blended with PET as in the present invention, the PET resin is sufficiently crystallized. Not only is the mold release property even better in the mold temperature range where crystallization occurs and the mold temperature range where there is almost no crystallization, but also the mold release property is improved in the intermediate mold temperature range. A PET resin composition can be obtained which exhibits excellent mold releasability and has excellent surface gloss. Therefore, when glass fibers, carbon fibers, aromatic polyamide fibers, silicon carbide fibers, potassium titanate fibers, etc. are blended into this PET resin composition, it has excellent mold release properties over the entire mold temperature, and improves mechanical properties. A molding material with excellent thermal properties can be provided. The polyethylene terephthalate used in the present invention is obtained from terephthalic acid or an ester of terephthalic acid and ethylene glycol by a conventional melt polymerization method, or it is obtained by subjecting it to solid phase polymerization. And polyester having at least 80 mol% or more of ethylene terephthalate repeating units means 80 mol% or more of ethylene terephthalate repeating units and other repeating units,
That is, it means a copolymer consisting of other copolymerization components, and various acid components and glycol components can be used as the above-mentioned other copolymerization components. For example, acid components include isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenylsulfone dicarboxylic acid, P-(2-hydroxyethoxy)benzoic acid, 5-sodium sulfoisophthalic acid, and adipic acid. , azelaic acid, sebacic acid, decane-1,10-dicarboxylic acid, dodecane-
1,12-dicarboxylic acid, tetradecane-1,14-
dicarboxylic acid, hexadecane-1,16-dicarboxylic acid, octadecane-1,18-dicarboxylic acid, icosane-1,20-dicarboxylic acid, decane-1,
16-dicarboxylic acid, 6-ethyl-hexadecane-
1,16-dicarboxylic acid, 6-ethyl-dodecane-
Examples include 1,12-dicarboxylic acid.
Examples of the glycol component include polyalkylene glycols such as propylene glycol, diethylene glycol, butylene glycol, pentyl glycol, neopentyl glycol, hexamethylene glycol, polyethylene glycol, and polytetramethylene glycol. Component (a) in the present invention is a polyolefin selected from the group consisting of ethylene-propylene copolymer, ethylene-propylene-butadiene copolymer, ethylene-propylene-isoprene copolymer, and ethylene-propylene-chloroprene copolymer. At least one compound selected from alicyclic carboxylic acids having a cis-type double bond in the ring or their acid anhydrides is added to the polyolefin copolymer in an amount of 0.001 to 10 mol% of the constituent monomers of the polyolefin copolymer. This is an added modified polyolefin copolymer. Two or more of these can also be used as a mixture. The alicyclic carboxylic acid having a cis-type double bond in the ring in the present invention includes, for example, cis-4-
Cyclohexene-1,2-dicarboxylic acid, endo-bicyclo-[2,2,1]-5-heptene-2,
3-dicarboxylic acid, methyl-endo-cis-bicyclo-[2,2,1]-5-heptene-2,3-dicarboxylic acid, endo-bicyclo-[2,2,1]-
Examples include 1,2,3,4,7,7-hexachloro-2-heptene-5,6-dicarboxylic acid. Particularly preferred are endo-bicyclo-
[2,2,1]-5-heptene-2,3-dicarboxylic acid. In the present invention, acid anhydrides of these alicyclic carboxylic acids can also be used, and when acid anhydrides are used, they do not necessarily have to be converted into acid anhydrides before being added to the polyolefin copolymer. The acid anhydride may be converted into an acid anhydride during the modification process of a polyolefin copolymer or after forming a polyester resin composition. The modified polyolefin copolymer in the present invention is obtained by adding an alicyclic carboxylic acid or its acid anhydride to the polyolefin copolymer. The modified polyolefin copolymer can be produced by various methods. For example, (a) the polyolefin copolymer and an alicyclic carboxylic acid or its acid anhydride are mixed with a radical generator, such as di- A method of melt-mixing and reacting in the presence of an organic peroxide such as tertiary-butyl peroxide, dicumyl peroxide, benzoyl peroxide, or (b) a method of reacting the polyolefin copolymer with an alicyclic carboxylic acid or its acid. Anhydrous and dispersed in water,
A method of heating and reacting in the presence of the above-mentioned radical generator or water-soluble peroxide can be adopted. The addition ratio of the alicyclic carboxylic acid or its acid anhydride to the polyolefin copolymer depends on the use of the polyester resin composition, the type of polyolefin copolymer, and the type of the alicyclic carboxylic acid or its acid anhydride. Although it varies, 0.001 to 10 mol% based on the constituent monomers of the polyolefin copolymer.
It is necessary to keep it within the range of . Component (b) in the present invention acts as a release property improver. In the general formula (), R ₁ and R ₂ are alkyl groups, but in order to increase the effect as a mold release improver, they must be long-chain alkyl groups, and the number of carbon atoms in the alkyl group is If the number is 4 or less, the effect as a mold release agent will be insufficient, so those having an alkyl group having 5 or more carbon atoms, more preferably 8 or more carbon atoms are used. Incidentally, R ₁ and R ₂ are alkyl groups, but also include those containing an unsaturated bond or other groups such as halogen, carboxyl group, hydroxyl group, epoxy group, etc. in the molecule. The numbers of m and n are not particularly limited, but as m and n become larger to a certain extent, the effect as a mold release agent improves; however, if they become too large, it becomes difficult to mix and disperse them uniformly in the PET resin. Usually, m,
n ranges from 1 to about 60, preferably from 2 to about 30, more preferably from 2 to about 20. Regarding the blending amount of each component in the polyester resin composition of the present invention, the blending amount of component (a) is PET resin.
If it is less than 0.1 part by weight per 100 parts by weight, the effect as a crystal nucleating agent or crystal growth promoter will be insufficient, and conversely, even if it is added in more than 10 parts by weight, it will not work as a crystal nucleating agent or crystal growth promoter. The effect is not proportional to the amount added, and any excess added merely acts as a filler. Therefore, the amount of component (a) to be blended is 0.1 to 10 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 7 parts by weight, based on 100 parts by weight of the PET resin. Furthermore, (b) component,
In other words, regarding the compounding amount of the compound represented by the general formula (), the optimum compounding amount varies depending on the structure of the general formula (), but if the amount of the component (b) is 100 parts by weight of PET resin. If the amount is less than 0.1 part by weight, the effect of improving mold releasability is insufficient;
If more than 1 part by weight is added, the properties such as mechanical strength and heat resistance of the polyester resin composition may deteriorate, so it is usually 0.1 to 10 parts by weight, preferably 0.1 to 7 parts by weight, and more preferably 0.2～5
Parts by weight. In this way, the polyester resin composition in which components (a) and (b) are blended with PET resin exhibits excellent mold release properties over the entire mold temperature range, but the polyester resin composition also contains glass fiber, When fibrous reinforcing materials such as carbon fibers, aromatic polyamide fibers, silicon carbide fibers, and potassium titanate fibers are blended, mechanical strength and heat resistance are improved, and an excellent molding material can be provided. The fibrous reinforcing material is often used in an amount of 5 to 150 parts by weight per 100 parts by weight of a polyester resin composition in which components (a) and (b) are blended with PET resin. The composition of the present invention may further include various inorganic or organic release agents, such as wax-based, silicone-based, and fluorine-based release agents, antioxidants, ultraviolet absorbers, colorants, and fillers, as necessary. system compounds can be blended. The polyester resin composition of the present invention can be manufactured by mixing in various ways, and the manufacturing method is not particularly limited, but usually, each component or additive is added to PET pellets and extruded. It is manufactured by mixing using a machine or kneader. The composition of the present invention can be molded into various forms, such as various molded articles, sheets, fibrous materials, tubular materials, etc., and used. Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Note that "parts" shown in Examples and Comparative Examples indicate "parts by weight." Evaluation of mold releasability was performed by the following method. Evaluation method 1 With the pressure of the ejector pin constant,
A test piece of 1/2 inch thick x 1/2 inch thick x 5 inch long was molded, and the minimum cooling time at which the ejector pin could be released from the mold without biting into the test piece was determined and compared relatively. Evaluation method 2 When a box-shaped molded product measuring 10 cm long x 7 cm wide x 4 cm deep (wall thickness 1.5 mm) was molded, the minimum cooling time at which the mold could be released was determined and compared relatively. Example 1, Comparative Example 1 Intrinsic viscosity (phenol/tetrachloroethane=
CMP (Tonen Petrochemical Co., Ltd., endo-bicyclo-[2,2,1]-5 to ethylene-propylene copolymer - adduct of heptene-2,3-dicarboxylic anhydride) 3 parts,
One part of the compound represented by the chemical formula () was mixed and kneaded using an extruder to prepare pellets (Example 1).
Similarly as a comparison polyethylene terephthalate
Create pellets by combining 100 parts with 3 parts of CMP,
(Comparative Example 1) After drying the pellets, the cylinder temperature was 240-260-270℃, the mold temperature was 125℃, and the injection time was
10 seconds, injection pressure 600Kg/ ^cm2 , 1/2 inch x 1/2
A test piece measuring 5 inches by 5 inches was molded, and the mold release property was evaluated by determining the minimum cooling time using the mold release evaluation method 1.

[Chemical formula] The composition of Comparative Example 1 did not release satisfactorily even after a cooling time of 58 seconds, but the composition of Example 1 had a minimum cooling time of 30 seconds. Example 2, Comparative Example 2 Polyethylene terephthalate 65 with intrinsic viscosity 0.68
parts and polyethylene glycol with a molecular weight of 2,000.
35 parts of 10% by weight copolymerized ethylene terephthalate polyester, 3 parts of CMP, 3 parts of the compound shown by the chemical formula (), glass fiber (Asahi Fiber Glass)
Co., Ltd., 3mm long chopped strand product number No. 429)
45 parts were mixed and kneaded using an extruder to prepare pellets (Example 2). Similarly, for comparison, pellets were prepared from a composition obtained by removing only the compound of chemical formula () from Example 2 (Comparative Example 2). After drying the pellets, ^1/2 m
A 2 inch x 1/2 inch x 5 inch test piece was molded, and the minimum cooling time at various mold temperatures (mold temperature) was determined based on evaluation method 1. The results are summarized in Table 1.

[ka]

[Table] Mix 30 parts of Stell, 2 parts of CMP, 4 parts of the compound represented by the chemical formula (), 15 parts of glass fiber (same as in Example 2), and 30 parts of talc, and knead with an extruder to make pellets. (Example 3). Further, pellets were also prepared in which the compound of chemical formula () in the composition of Example 3 was changed to chemical formula () (Example 4). For comparison, pellets were prepared by removing only the compound represented by the chemical formula () from the composition of Example 3 (Comparative Example 3). After drying the pellets, the pellets were vertically heated under the conditions of a cylinder temperature of 240-260-270℃, an injection pressure of 300-600Kg/ ^cm2 , and an injection time of 10 seconds.
A box-shaped molded product measuring 10 cm x width 7 cm x depth 4 cm (wall thickness 1.5 mm) was molded, and the minimum cooling time at various mold temperatures was determined based on evaluation method 2. The results are summarized in Table 2.

[ka]

[ka]

[Table] It can be seen from this that when chemical formulas () and () are blended, excellent mold release properties are exhibited in the entire mold temperature range.

Claims (1)

[Scope of Claims] 1. Based on 100 parts by weight of polyethylene terephthalate or a polyester having at least 80 mol% of ethylene terephthalate repeating units, (a) ethylene-propylene copolymer, ethylene-
Propylene-butadiene copolymer, ethylene-
A polyolefin copolymer selected from the group consisting of propylene-isoprene copolymer and ethylene-propylene-chloroprene copolymer, and an alicyclic carboxylic acid having a cis-type double bond in the ring or its acid anhydride. 0.1 to 10 parts by weight of a modified polyolefin copolymer to which at least one selected compound is added in an amount of 0.001 to 10 mol % based on the constituent monomers of the polyolefin copolymer, and (b) 0.1 part of a compound represented by the following general formula (). ~Ten
A polyester resin composition formed by blending parts by weight. [Chemical formula] However, X: direct bond, alkylene group, -SO ₂
-, -S-, -O- or -CO
- R ₁ , R ₂ : Alkyl group having 5 or more carbon atoms, R ₁ , R ₂ are the same or different groups R ₃ , R ₄ : H, alkyl group or halogen, R ₃ , R ₄ are the same or different groups m, n: integer greater than or equal to 1