JPS5928347B2 - polyester resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite composition developed to be suitable as a material for molding precision wear-resistant parts such as gears and cams, and in particular has superior wear resistance and dimensional stability compared to conventional polyester resin products. , to provide a composition with improved rigidity etc. at a low cost.

In recent years, various resins, especially polyester resins (polyethylene terephthalate and polybutylene terephthalate) with excellent wear resistance, have been used for materials such as gears and cams in sewing machines, etc. due to demands for wear resistance, weight reduction, quietness, and low-cost mass production. However, unreinforced polyester resins not only have inferior mechanical strength and heat resistance, but also these unreinforced polyesters themselves have a high secondary transition point and have a low melt viscosity at that temperature, but their crystallization rate during molding is low. Appearance due to greatness,
Both the physical properties and the product tend to lack uniformity, and the molding shrinkage rate is high, so the molded product tends to warp significantly.Therefore, it was necessary to compensate for these defects with a filler.

Therefore, attempts have been made to use plastic materials filled with glass fiber (or talc) for items that require good strength and precision, such as sewing machine gears or cams. Even when used as a resin (FRTP), the glass fibers have a considerable degree of directionality, resulting in insufficient and unstable dimensional accuracy, making them unsuitable for parts with complex precision shapes, and especially with roughness and abrasion (
There were problems such as poor taper wear value, damage to the mating material in the application, and easy wear and tear on the molding equipment. In view of the above, as a result of studies, the present invention has properties as shown in Table 3: it is naturally produced at low cost, has heat resistance, is highly flexible, has excellent cleavability, and has a significantly lower water content than other micas. Focusing on Procopart Kiai mica produced in Canada, it was filled into a resin as shown in the following example, and improvements in various physical properties were observed, particularly improvements in abrasion resistance, dimensional stability, and elastic modulus.

Example [I] 0.1% liquid paraffin is added to polybutylene terephthalate (PBT) resin, and bound water is 1.5% or less by peeling and cleaving with a cage mill etc., and the aspect ratio is 30 or more.
20wt% of the 0 mesh phlogopite treated with silane coupling is well kneaded using, for example, a pressure kneader, and 10w of glass beads (GB) are added with If6 and further kneaded to fully disperse the filler. The pellets were formed into test pieces by injection molding, and the physical properties were compared with other comparative materials as shown in Table [1] below.

Example [] 10 wt (f) of the above-mentioned phlogopite which has been subjected to a coupling treatment with polybutylene terephthalate (PBT) resin and a particle size of 325 mesh with an aspect ratio of 50 or more is kneaded in a pressure kneader, cooled, and then pulverized to pelletize. The depth of wear was compared between molded sewing machine cams and cams molded to the same shape using other commercially available materials (Table 2 below).

That is, in the present invention, the polyester resin composite composition in particular becomes extremely brittle when it contains water, and mica usually absorbs bound water by 3%.
Phlogopite produced in Canada starts releasing water at 550°C and has a water content that is particularly lower than that of ordinary mica (1.5
%), moisture has almost no adverse effect when the resin is molded at a temperature of around 250°C, and since it has excellent cleavage properties, the aspect ratio can be easily increased compared to ordinary mica, resulting in improved roughness and abrasion properties and elasticity. The particle diameter of 200 to 400 mesh obtained by exfoliating the above-mentioned phlogopite with bound water of 1.50 I) or less using a cage mill etc. and cleaving it to an aspect ratio of 20 or more, preferably 50 or more. Mica flakes are infiltrated with an aminosilane or amidosilane coupling agent, kneaded into a resin, and if necessary, an appropriate amount of glass beads of 5 to 50 μm, which have also been subjected to a silane coupling treatment, are added, kneaded, and then cooled and pulverized. The above-mentioned treatment for mica, which is pelletized and used as a molding material, is to make it easier to wet with the non-polar component (coupling agent) present on the liquid surface, and the treatment for glass beads is also to obtain the same effect. However, polybutylene terephthalate (PBT) is suitable as the main polyester material, and the phlogopite filled in PBT is relatively uniformly dispersed, has little directionality, and has good dimensional stability. If it is necessary to increase the surface hardness of the product, reinforcement with glass beads is effective.In this case, the total amount of mica and glass beads is preferably 40% by weight or less, and especially mica is 20w.
t% or less is overall effective; if it is more than 30wt%, the so-called weld strength decreases greatly, and if the mica particle size is more than 100μ, the outer appearance is poor, and the aspect ratio is 1.
If it is less than 0, no effective improvement in physical strength can be expected;
Further, when glass beads are also kneaded, this kneading is carried out after kneading the mica in order not to impair the uniform dispersion of the phlogopite.

Claims (1)

[Claims] 1. Average aspect ratio of coupling treated polybutylene terephthalate resin of 20 or more, bound water content of 1.5.
% or less, dehydration temperature 500℃ or more, chemical formula K_2Mg_4
＿． _3_2Fe_1_. _1_6Al_0_. ＿３＿
8 [Si_5_. _7_5O_2_0Al_2_. ＿２
_5](OH)_4F_2 1 to 30% by weight of Canadian phlogopite is kneaded and further coupled to glass beads with a particle size of 5 to 50μ, which together with the above mica have a total of 40% by weight.
A polyester resin composition obtained by kneading 0 to 20% by weight within a range not exceeding %.