JPH0216150A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having improved aging characteristics, a high strength and a high modulus by adding a potassium titanate whisker to a thermoplastic polyester resin of a high terminal carboxyl concentration. CONSTITUTION:A potassium titanate whisker is added to a thermoplastic polyester resin (e.g., terephthalic acid/ethylene glycol/p-hydroxybenzoic acid liquid crystal polyester) having a terminal carboxyl concentration >=100 milliequivalent/kg. In this way, a polyester resin composition which retains the excellent properties inherent in the polyester resin and the excellent performances of the potassium titanate whisker as a filler and has excellent mechanical properties, especially, high bending modulus and improved aging characteristics can be obtained. It has a low dimensional change upon absorption of moisture, so that it can be used extensively in the fields of electrical and electronic devices and components, general machine parts and automobile parts, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a polyester resin composition having improved aging properties, high strength, and high modulus.

(Conventional technology) Engineering plastics with high strength, high elastic modulus, and excellent heat resistance are used in a wide range of fields, but in recent years, with remarkable technological innovation, there has been a demand for the development of high-performance resins. ing.

In recent years, polyester resin, which is one of the engineering plastics, especially polyethylene terephthalate polybutylene terephthalate, liquid crystal polyester resin, etc.
Because of its good heat resistance, low water absorption, and good dimensional stability, it can be reinforced with fillers and used as electrical/electronic equipment parts.
It has come to be widely used in fields such as general machinery parts, consumer goods, and automobile parts.

As a filler, glass fiber has generally been used in the past, but in recent years, potassium titanate whiskers have been in the spotlight as a filler that provides high strength and high elastic modulus. This whisker gives stable and extremely high performance to many resins such as polyamide, polyolefin, polyacetal, etc., but polyester resin compositions containing this whisker,
Polyester decomposes over time, causing a decrease in strength.

There was a problem that the aging characteristics were poor.

This is considered to be because the alkaline content remaining in the potassium titanate whisker hydrolyzes the polyester together with the moisture in the atmosphere.

(Problems to be Solved by the Invention) The present invention aims to provide a polyester resin composition with improved aging characteristics while taking advantage of the high performance of potassium titanate whiskers as a filler and the excellent properties inherent in polyester resin. That is.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors found that it is necessary to reduce the terminal carboxyl group concentration of polyester as low as possible in order to suppress the hydrolysis of polyester. Contrary to the conventional wisdom that this is the case, the present inventors have discovered that aging characteristics can be improved by using a polyester resin with a high concentration of terminal carboxyl groups and filling the resin with potassium titanate whiskers, thereby achieving the present invention.

That is, in the present invention, the terminal carboxyl group concentration is 100
The gist of the invention is a polyester resin composition in which potassium titanate whiskers are contained in a thermoplastic polyester resin having a millimeter ffi/kg or more.

The polyester in the present invention is a substantially linear thermoplastic material, and is synthesized by a conventional method by appropriately combining a dicarboxylic acid component such as a primary dicarboxylic acid component with a diol component and/or a hydroxycarboxylic acid component.

Dicarboxylic acid components: Terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, methyl terephthalic acid, methyl isophthalic acid, succinic acid, adipic acid, sebacic acid, Decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid diol component; ethylene glycol, trimethylene glycol.

Tetramethylene glycol, hexamethylene glycol, decamethylene glycol, cyclohexane dimetatool, 4,4'-dihydroxybiphenylhydroxycarboxylic acid component; hydroxybenzoic acid, hydroxyethoxybenzoic acid, 6
-Hydroxy-2-naph 1-11 More specifically, terephthalic acid and isophthalic acid are used as the dicarboxylic acid component, and ethylene glycol and hexamethylene glycol are used as the diol component.

It is synthesized from components selected from cyclohexane dimetatool, 4,4'-dihydroxybiphenyl, p-hydroxybenzoic acid as a hydroxycarboxylic acid component, and 6-hydroxy-2=naphthoic acid.

Preferred polyesters in terms of practicality and resin performance include polyethylene terephthalate, polybutylene terephthalate, terephthalic acid/ethylene glycol/p-hydroxybenzoic acid based liquid crystal polyester, p-hydroxybenzoic acid/6-hydroxy-2-naphthoic acid based polyester. Examples include liquid crystal polyester, and liquid crystal polyester is the most preferred because a high elastic modulus can be obtained and the effect of improving aging characteristics is remarkable.

In the present invention, the terminal carboxyl group concentration of polyester is measured by dissolving a sample in dioxane and titrating with a potassium hydroxide solution using cresol red as an indicator.1 The polyester resin used in the present invention is , the terminal carboxyl group concentration is 100 milliliter/it/
kg or more.

Polyester resins with a high concentration of terminal carboxyl groups are produced by adding monocarboxylic acid or using a slightly excessive amount of dicarboxylic acid during the polycondensation process of polyester production, or by thermally decomposing or acidolyzing the polyester. It can be obtained by increasing the number of carboxyl groups.

For example, in the case of a terephthalic acid/ethylene glycol/p-hydroxybenzoic acid-based liquid crystalline polyester, polyester fragments are formed by acidolysis of polyethylene terephthalate with p-hydroxybenzoic acid, and then the terminal ends can be easily obtained by performing a thickening reaction under reduced pressure. A polyester having a carboxyl group concentration of 100 meq/kg or more is obtained. In addition, when synthesizing polyester using this method, it will not dissolve in dioxane if the ratio of p-hydroxybenzoic acid component exceeds 70 mol% of the repeating unit, but measurements for polyester with a low ratio of p-hydroxybenzoic acid component When the terminal carboxyl group concentration is estimated by extrapolating the values, all injection moldable materials have a weight of 100 milliequivalents/kg or more, which corresponds to the polyester in the present invention.

Next, the potassium titanate whisker in the present invention is a type of high-strength single crystal fiber made of potassium titanate represented by the general formula %, and those made of potassium hexatitanate with n=6 are particularly preferable. In the present invention, fibers with an average fiber length of 5 to 150μ and an average fiber diameter of 0.05 to 2.0μ can be used, but in particular those with an average fiber length of 10 to 30μ and an average fiber diameter of 0.1 to 0.5μ can be used. Preferably.

Note that the potassium titanate whisker may contain an alkaline content as long as it remains in a normal manufacturing process in an amount of less than 0.5% by weight.

Additionally, potassium titanate whiskers can be added as needed.
It may be used as a filler after being treated with a silane coupling agent such as T-glycidoxypropyltrimethoxysilane or T-aminopropyltriethoxysilane or a surface treatment agent such as a titanate camping agent.

The amount of potassium titanate whiskers to be filled is not particularly limited, but it is preferably 5% by weight or more, particularly 10% by weight or more so that the reinforcing effect thereof can be sufficiently exhibited.

Further, the means for incorporating the potassium titanate whiskers into the polyester resin is not particularly limited;9 Usually, the potassium titanate whiskers and the polyester resin are mixed separately, or after they are premixed using a mixer ball mill or a blender. A method is adopted in which the mixture is supplied to a melt mixer and mixed.

Note that the polyester resin composition of the present invention contains antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, 9 colorants (dyes, pigments), flame retardants, to the extent that their effects are not affected by the t-member.
Additives such as antistatic agents can be included.

(Function) The reason why the polyester resin composition of the present invention has improved aging properties is not clear.

It is assumed that one reason is that the alkaline content remaining in the potassium titanate whisker is neutralized by the terminal carboxyl of the polyester.

(Example) Next, two embodiments of the present invention will be specifically explained using examples.

Note that the intrinsic viscosity is a value measured at 30°C using an equal weight mixture of phenol and tetrachloroethane as a solvent.

In addition, the tensile strength and flexural modulus are determined by ASTM D6, respectively.
Measurements were made on injection molded products with a thickness of 1/8 inch in accordance with 38 and D790.

Examples 1-2 Ordinary high viscosity polyethylene terephthalate (PET)
After adding an appropriate amount of terephthalic acid to perform an acidolysis reaction, a viscosity increasing reaction was performed under reduced pressure to obtain an intrinsic viscosity of 0.65. A polyester resin having a terminal carboxyl group concentration of 135 meq/kg was obtained.

This polyester resin and potassium titanate whiskers
Amount of free potassium content (boiling a certain amount of sample in water for a long time and quantifying the eluted potassium using atomic absorption spectrometry) 0.
06 heavy weight%, fiber length 20-120μ fiber diameter 0.3-1.
0μ] and the whisker filling amount was 20% by weight (Example 1
) and 30% (Example 2) were mixed and made into chips.

The mixing was carried out using a twin-screw extrusion model 1i: PcM-45 manufactured by Ikegai Tekko 01, by supplying the polyester resin from the first supply hopper and the whiskers from the second supply hopper.

This chip was injection molded to prepare a test piece, and its initial characteristics and aging characteristics were measured.

Comparative Examples 1 and 2 As a polyester resin, the intrinsic viscosity was 0.65. Ordinary PE with a terminal carboxyl group concentration of 35 meq/kg (Comparative Example 1) and 70 meq/kg (Comparative Example 2)
A test similar to that in Example 2 was conducted using T.

Examples 3 to 4 The following method was used to prepare a product consisting of ethylene terephthalate units and p-hydroxybenzoic acid residue units in a molar ratio of 40:60, with an intrinsic viscosity of 0.67 and a terminal carboxyl group concentration of 17.
0 milliliter/kg liquid crystalline polyester resin (LCP)
I got it.

That is, 12 kg of PUT and 18 ksr of acetoxybenzoic acid were charged into a reactor, and after sufficiently drying by repeating depressurization and nitrogen purge, 3 kg of acetic anhydride was added.
The temperature was raised to 275°C, acidolysis reaction was carried out for 1 hour under a nitrogen stream, and then the pressure was gradually reduced to a final temperature of 0.25).
A thickening reaction was carried out for 5 hours as a sample.

As a polyester resin, the LC thus obtained
A test similar to Example 1 and Example 2 was conducted using P.

Comparative Example 3 As a polyester resin, Lcp in Example 3 was reacted with a monofunctional epoxy compound (trade name: Cardurer E10, manufactured by Yuka Seel Co., Ltd.), and the terminal carboxyl group concentration was reduced to 7.
A test similar to that in Example 3 was conducted using 0 mm/kg.

The results of the above Examples and Comparative Examples are summarized in Table 1.

Table 1 Note: fl) COOH is polyester) L4tff indicates the terminal carboxyl group of the finger (unit: mm/ffl/'kg).

(2) Aging characteristics For (1), perform normal aging at old °C, and 0 seedlings ■ α until the MJ times'+” %
Funaru, [11] After six months of singing, Shirtejida'
J times gxu rate (indicates (goods).

(Effects of the Invention) According to the present invention, the excellent properties inherent to polyester resin and the excellent performance of potassium titanate whiskers as a filler are utilized, resulting in excellent mechanical properties.

A polyester resin composition having particularly high flexural modulus and improved aging properties is provided.

And 9. The polyester resin composition of the present invention is as follows.

Since there is little dimensional change due to moisture absorption, it can be used in a wide range of fields such as electrical and electronic equipment parts, general mechanical parts, consumer goods, and automobile parts.

Claims (1)

[Claims] (1) Terminal carboxyl group concentration is 100 milliequivalents/kg
A polyester resin composition comprising the above thermoplastic polyester resin containing potassium titanate whiskers.