JPS62197446A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To contemplate improvements in the mold release characteristics, the strength and the appearance of moldings, by blending a compsn. consisting of polyethylene terephthalate and glass fiber with an ester derived from a tricarboxylic acid and a higher alcohol. CONSTITUTION:100pts.wt. compsn. consisting of 40-95wt% polyethylene terephthalate and 5-60wt% glass fiber is blended with 0.02-2pts.wt. ester derived from a tricarboxylic acid and a higher alcohol. Examples of the tricarboxylic acid are satd. aliph. tricarboxylic acids and arom. tricarboxylic acids, among which citric acid is particularly preferred. Preferred examples of the higher alcohol are 16-24C higher alcohols and mixtures thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyester resin composition used as an engineering plastic in the fields of electrical, electronic parts, automobiles, etc.

[Conventional technology]

Glass fiber reinforced polyethylene terephthalate (CF-P
ET) has excellent rigidity, impact strength, and heat resistance, and is widely used industrially as an engineering plastic.

By the way, when obtaining a molded article using this resin, efforts are being made to improve the mold releasability and shorten the molding cycle as much as possible. For this purpose, a compound having a mold release effect is generally added. Many such compounds are known as mold release agents. For example, esters of -valent higher fatty acids and higher alcohols (JP-A-59-191757 fg)
, ester of tetrahydric alcohol pentaerythritol and higher fatty acid (Japanese Unexamined Patent Publication No. 191756/1983)
and so on.

However, these mold release agents (i) have excellent mold releasability, but may reduce the strength of the molded product or cause problems in appearance, and (ii) do not cause problems in strength or appearance. However, there are problems such as poor mold releasability, and none of them necessarily satisfy all requirements, and in recent years, improvements have been desired as molding resins for so-called high cycle applications.

[Problem that the invention seeks to solve]

The present invention has been made in view of these problems, and it is an object of the present invention to provide a polyester resin composition that provides molded articles with good strength and appearance, and has excellent mold release properties.

[Means for solving problems]

As a result of the inventors' studies to solve the above problems,
It has been found that by blending a predetermined amount of ester of tricarboxylic acid and higher alcohol, mold releasability is surprisingly improved, and the strength and appearance of the molded product are also improved.

That is, the polyester resin composition of the present invention contains 0.0 parts by weight of ester of tricarboxylic acid and higher alcohol per 100 parts by weight of a composition consisting of 40 to 95% by weight of polyethylene terephthalate and 5 to 60% by weight of glass fiber.
It is characterized by containing 5 to 2 parts by weight.

First, polyethylene terephthalate (hereinafter abbreviated as PET) in the present invention is a linear polyester obtained by condensing terephthalic acid or dialkyl terephthalate with ethylene glycol, or a linear polyester obtained by condensing terephthalic acid or dialkyl terephthalate with ethylene glycol. A copolymerized polyester having a main component copolymerized with a copolymerizable third component, and a mixture of the linear polyester and the copolymerized polyester are included. Examples of the third component include isophthalic acid, naphthalene-2,6
-Dicarboxylic acid, adipic acid, diphenyl ether-4
, 4'-dicarboxylic acid, acid components such as sebacic acid, propylene glycol, neopentyl gelcol, diethylene glycol, cyclohexane dimetatool, 2.2
-Glycol compounds such as -bis(4-hydroxyphenyl)propane, oxyacids such as p-oxybenzoic acid and p-hydroxyethoxybenzoic acid. The PET preferably has an intrinsic viscosity of 0.5 or more, more preferably 0.55 or more, as measured at 30°C using a phenol/tetrachloroethane mixed solvent (1/1 weight ratio) solution. This is particularly preferred.

As the glass fiber in the present invention, any of glass fibers made of E glass, A glass, or C glass can be used, and a mixture of these can also be used. The length of the glass fiber in the polyester resin composition is preferably 0.02 to 2 lengths, particularly preferably 0.05 to 1 length. This glass fiber is
When kneading with T, the glass fibers may be broken by the kneader, so the size of the glass fibers when kneading is as follows:
Usually, it is preferable that the length is O,1 to 6 lengths.

In addition, the diameter of such glass fibers is usually 1 to 20μ.
m is sufficient. Further, the form of the glass fiber is not particularly limited, and may be, for example, roving, milled fiber, chopped strand, or the like. Further, it is preferable that the glass fiber be subjected to surface treatment such as silane treatment, borane treatment, chromium treatment, etc. and then bound with epoxy resin. This is because such treatment improves the adhesion between PET and the glass fiber.

In the composition consisting of PET and glass fibers, the amount of PETO is 40-95% by weight, preferably 50-95% by weight. If PET is less than 40% by weight, the amount of PET is small;
The amount of glass fiber increases and the appearance of the molded product is impaired. When PET exceeds 95% by weight, the moldability of the resin composition decreases.

Further, the amount of glass fiber in the above composition is 5 to 60% by weight.
, preferably 8 to 50% by weight. If the glass fiber content is less than 5% by weight, the excellent heat resistance and rigidity, which are the characteristics of glass fiber reinforced polyethylene terephthalate, will not be noticeable. When the glass fiber content exceeds 60% by weight, not only does the weight of the molded product increase, but there is no improvement in heat resistance and rigidity, the fluidity is poor, and the moldability is poor.

Examples of the ester of tricarboxylic acid and higher alcohol in the present invention include esters of saturated aliphatic tricarboxylic acid and aromatic tricarboxylic acid and higher alcohol. As the saturated aliphatic tricarboxylic acid, C3 to C3
C3 to C1 tricarboxylic acids are preferred. In particular, C4 tricarboxylic acids are preferred.

Specific examples include (citric acid) (tricarballylic acid) (1,1,2-ethane C0OH tricarboxylic acid) (1,1,2-propanetricarboxylic acid) C1,C0OH (1,1,3-propane (1,2 , 3-nonanetricarboxylic acid) tricarboxylic acid) HOOCCIIg
CHCHZ C0OH
zCH-CHz(Jig C0OH0OH (1,2,4-butanetricarboxylic acid) CH3C00H (1,3,4-pentanetricarboxylic acid), oon 1100 CCII□CIl-CII□CIl□CIl
, C00N0OH (1,2,5-pentanetricarboxylic acid) CH,zCl
hCOOll 1100cmC11 CHgCHzCOOII (1,3,5-pentanetricarboxylic acid) CI, C00
H (1,4,5-hexanetricarboxylic acid)HOOC-C
HgCHtCII□CH-CHtCHtCHzCOOH
0OH (1,4,7-heptanetricarboxylic acid)HOOC-C
HzC1hCH□CHtCH-CHzCHzCOOIl
0OII (1,3,7-heptanetricarboxylic acid) 0OII HOOC-CIl 2CIl□cotc11□C1l□
CHOO11 (11,6-hexanetricarboxylic acid)H00C-CH
z CII□CII□Cl1-CIlICIl□COO
110OH (1,3,6-hexanetricarboxylic acid)HOOCCH
zCHzCII (cut) l. COO110O11 (1,3,13-tridecanetricarboxylic acid) 1100
CCII□CIl□CIl (CIlz) + zc
OOH0O11 (1,3,15-pentadecanetricarboxylic acid) OOH CH: +C) lzclIzclI□C1I□CIl□c
-CIIzCOOH0OH (1,2,2-octanetricarboxylic acid)0O11 CI, 1(CIl□) s -C-CH□CH□CH,
Examples include COO110OH (1,4,4-decanetricarboxylic acid).

Examples of aromatic tricarboxylic acids include (hemimellitic acid), C0QH (trimellitic acid), and (trimesic acid).

Among these, citric acid is particularly preferred.

As the higher alcohol, higher alcohols of 012 or higher and mixtures thereof are used, and specific examples thereof include lauryl alcohol (C+Z), tridecyl alcohol (CH3), myristyl alcohol (CI4), pentadecyl alcohol (C+s), and cetyl alcohol. (C
H6), margaryl alcohol (C17), stearyl alcohol (clll), nonadecyl alcohol (ct
q), eicosyl alcohol (C2゜), behenyl alcohol (czz), lignonaryl alcohol (CZ
4) , ceryl alcohol) L/ (C20) 1. t
') Yu D shi/L/7) Lt':1-/L/ (C
zs), merisil alcohol (C3°), and lauryl alcohol (Czz). Preferred are C16 to C24 higher alcohols and mixtures thereof.

The above-mentioned ester of tricarboxylic acid and higher alcohol used in the present invention may be a partial ester or a whole ester, but it is preferable to use a whole ester. Among them, all esters of citric acid and stearyl alcohol (tristearyl citrate), all esters of citric acid and behenyl alcohol (tribehenyl citrate)
and all esters of citric acid and cetyl alcohol (tricetyl citrate) are particularly preferred. Moreover, in the present invention, these esters can be used alone or in combination of two or more.

In the present invention, the blending amount of the ester of tricarboxylic acid and higher alcohol is 0.05 to 2 parts by weight, preferably 0.08 to 1. 5
Part by weight. If the amount of ester blended is less than 0.05 parts by weight, no effect of improving mold releasability will be observed, and if it exceeds 2 parts by weight, the appearance of the molded product will deteriorate. In particular, it is undesirable because it becomes colored during heating. Moreover, if it exceeds 2 parts by weight, the strength of the molded product will decrease.

In addition to the above-mentioned components, the polyester resin composition of the present invention may contain antioxidants, flame retardants, ultraviolet absorbers, antistatic agents, lubricants, colorants, etc., which are usually added to polyester resin compositions, if necessary. Additives can be added.

In particular, when talc, ionomer, etc. are added as a crystallization promoter, moldability is improved.

The method for preparing the polyester resin composition of the present invention is not particularly limited, but for example, a predetermined amount of glass fiber, an ester compound, and other additives are added to PET, and It can be adjusted by melt-kneading in a conventional manner using a twin-screw extruder or the like.

Furthermore, it is also possible to use the ester compound by externally adding it to a pelletized PET molding material to form a polyester resin composition during molding.

〔Example〕

Hereinafter, the present invention will be further explained based on Examples, but the present invention is not limited to these Examples.

Examples 1 to 8 Comparative Examples 1 to 5 Predetermined amounts of polyethylene terephthalate, glass fiber, and ester compound shown in the table were mixed and melt-kneaded at 280°C using a twin-screw extruder to form pellets. The obtained pellets were molded using an injection molding machine (Sumitomo Necool N515/15).
0, manufactured by Sumitomo Heavy Industries) at a cylinder temperature of 270°C and a mold temperature of 140°C to prepare a 1/4 inch thick test piece, and its bending strength was measured.

The results are shown in the table.

The mold releasability and appearance were measured by the methods shown below. The results are shown in the table.

After drying the above pellets at 120°C for 6 hours, the pellets were placed in an injection molding machine (
8 steel N100Bu type (manufactured by Japan Steel Works) was used, and the diameter was 98° under the conditions of cylinder temperature 270°C and mold surface temperature 90°C.
A cylindrical molded product with a length of 1 m and a length of 50 dragons is formed. The ejection pressure at this time was measured using a pressure sensor.

In addition, a pressure sensor is installed on the hydraulic pressure to measure the force required to eject the molded product after one cycle of molding is completed and the mold is opened.
The protruding resistance value) can be detected using an electromagnetic oscilloscope. The lower the protrusion resistance value, the better the mold releasability.

” The appearance was determined by visually observing the gloss and color tone of the cylindrical molded product.

○... Good △... Some gloss and color unevenness ×... Gloss and color unevenness According to the margin table below, as is clear from Examples 1 to 8 and Comparative Examples 3 to 5, the book is The polyester resin composition of the invention has excellent mold releasability, and the molded product has no decrease in strength and has a good appearance.

Furthermore, as is clear from Comparative Example 1 and Comparative Example 2, if the amount of the ester compound of the present invention added is less than 0.05 parts by weight, there is no effect of improving the mold releasability, and if it exceeds 2 parts by weight, the mold releasability is improved. However, it can be seen that the appearance of the molded product deteriorates and the strength also decreases.

[Effects of the Invention] The polyester resin composition of the present invention has excellent mold releasability, and the strength and appearance of molded products are also good, and its industrial value is great.

Claims (1)

[Claims] 1. It is characterized by blending 0.05 to 2 parts by weight of an ester of tricarboxylic acid and higher alcohol to 100 parts by weight of a composition consisting of 40 to 95% by weight of polyethylene terephthalate and 5 to 60% by weight of glass fiber. Polyester resin composition.