JPS59164358A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having excellent mechanical properties and weather resistance and capable of giving ivory-like moldings (appearance, touch, collision sound, etc.), by blending a polyester resin, a reinforcing fiber, a fluororesin powder and a crystallization accelerator. CONSTITUTION:100pts.wt. polyester (e.g. a resin having an intrinsic viscosity of 0.4 or above and mainly composed of polyethylene terephthalate), 30-140pts.wt. reinforcing fiber (e.g. glass fiber chopped strand or potassium titanate whisker), 3-80pts.wt. fluororesin powder having an average particle size of 50mu or below (e.g. polytetrafluoroethylene powder) and 0.001-10pts.wt. crystallization accelerator (e.g. sodium stearate) are blended together in such a proportion as to give moldings having a specific gravity of 1.6 or above.

Description

[Detailed description of the invention] The present invention relates to polyester resin compositions.

More specifically, the present invention relates to a polyester resin composition that has excellent mechanical properties and weather resistance, and can provide molded articles having ivory-like appearance and acoustic properties.

Ivory has been widely used as a material for crafts since ancient times due to its excellent texture and physical properties.

Furthermore, in the early modern period, ivory came to be used in many applications such as acoustic materials and game materials.

For example, smelted ivory for billiards has a high coefficient of repulsion and is moderately sharp and strong, while ivory mahjong pie has a good stirring sound and a moist feel, making it a popular luxury item. In addition, the ivory shamisen's pick has a suitable weight and has a good feel, making it easy for the player to handle.
It is superior to other materials in terms of not damaging the strings and having less wear on the plectrum itself. Furthermore, due to its excellent physical properties, ivory is used for piano keys, earpieces, seals, etc., and the demand for these products continues to increase year by year.

However, due to overhunting over the past several centuries, elephants are now rare and are under strict protection, and the amount of ivory harvested is decreasing year by year. As a result, a large supply-demand gap has arisen, and ivory products have become increasingly expensive and difficult to obtain.

Conventionally, since ivory is expensive, hard wooden products such as beracola have been used as substitutes for a long time. However, these substitutes had considerably inferior characteristics compared to ivory in terms of feel, tone, impact sound, etc., and were not satisfactory as substitutes.

Furthermore, in recent years, molded products made of thermoplastic resins such as ABS resin have been developed, and some are used as substitutes for ivory.

Some of these thermoplastic resins are comparable to ivory in terms of strength and abrasion resistance, but they are inferior in feel, tone, etc., and are currently ranked below intermediate quality as substitutes for ivory. do not have.

Under these circumstances, there has been a strong desire to develop a material that has the same feel, tone, and appearance as ivory.

An object of the present invention is to provide a polyester resin composition that has excellent mechanical properties and weather resistance, and has the same feel, tone, and appearance as ivory.

As a result of intensive study to achieve the above object, the inventors of the present invention found that
The present invention was completed based on the discovery that a molded product having properties similar to those of ivory can be obtained by molding a composition containing a polyester resin, a fibrous filler, a fine fluororesin powder, and a crystallization accelerator.

That is, the polyester resin composition of the present invention contains 100 parts by weight of polyester resin, 30 to 140 parts by weight of fibrous filler, 3 to 80 parts by weight of fluororesin powder having an average particle size of 50 μm or less, and 0.001 parts by weight of crystallization promoter. -10 parts by weight, and has a specific gravity of 1.6 to 7 after molding.

In the following, the present invention will be explained in more detail.

The polyester resin used in the present invention is a polymer or copolymer obtained by a condensation reaction containing terephthalic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof as main components.

The copolymer used usually has 30% or less of its acid component replaced with another copolymer component.

Acid components as copolymerization components include phthalic acid, isophthalic acid,
Adipic acid, sebacic acid, naphthalene dicarboxylic acid, anthracene dicarboxylic acid, cyclosane dicarboxylic acid, and combinations thereof, and diol components include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, and neopentyl. Mention may be made of glycols, hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)furopane, bis(4-hydroxyphenyl)sulfone and combinations thereof.

Particularly preferably, the copolymer contains 80% by weight of ethylene terephthalate units or butylene terephthalate units.
Polyester resins containing the following are used.

The intrinsic viscosity "η" of the polyester resin is usually 0.4 or more, preferably 0.5 to 1.6. [η] is 0
．． If it is lower than -4, sufficient strength cannot be obtained and it becomes easy to break, which is not preferable. On the other hand, if [η] is too high, the screw torque per rotation during injection molding will be high, the screw will likely stop or bite defects, and the appearance of the surface of the obtained molded product will deteriorate. Therefore, in practice, 1.
6 is the upper limit.

Note that the intrinsic viscosity [η] is 111 at 25°C in a solvent of phenol/tetrachloroethane = 50,750 (weight ratio).
11 The value determined from the determined solution viscosity.

The fibrous filler is a component that increases the rigidity and strength of the polyester resin composition and improves its tone.

Examples of fibrous fillers include glass fibers, inorganic fibers other than glass fibers, carbon fibers, and heat-resistant organic fibers, and more specifically, fiber diameters of 5 to 20 km and fiber lengths of 10 mm.
The following chopped strands of glass fiber or carbon fiber, milled glass fiber, pitch-based carbon fiber, potassium titanate whiskers with fiber # diameter of 0.05μ5m or more, silicon carbide whiskers, aromatic polyamide Fam, aromatic polyimide fiber, Mention may be made of aromatic polyamideimide fibers and M1 combinations thereof.

Among these, chopped strands of glass m fibers, potassium titanate whiskers, and silicon carbide whiskers are particularly preferable, and carbon fibers are products with characteristics such as a black molded product and an appearance with a unique texture. It is also preferable because it provides the following.

The content of the fibrous filler is in the range of 30 to 140 parts by weight based on 100 parts by weight of the polyester resin. If it is less than 30 parts by weight based on the polyester resin, the resulting molded product will have a low elastic modulus and poor acoustic properties. On the other hand, if it exceeds 140 parts by weight, the surface condition of the molded article will deteriorate, which is not preferable.

Fluorine resin powder is an essential component of the present invention for improving the feel of the polyester resin composition and imparting ivory-like lubricity.

As fluororesin powder, polytetrafluoroethylene,
Examples include polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, polyvinylidene fluoride, and chlorotrifluoroethylene-vinylidene fluoride copolymer, with polytetrafluoroethylene being particularly preferred. .

The average particle size of the fluororesin powder is 5 Qgm or less. If the average particle size exceeds 50 pm, the appearance and properties of the molded product will become non-uniform.

The content of the fluororesin powder is 3 to 80 parts by weight per 100 parts by weight of the polyester resin. If it is less than 3 parts by weight, it will be difficult to obtain a molded article with an ivory-like feel, and if it is more than 80 parts by weight, shapeability and injection moldability will be significantly impaired, which is not preferable.

The crystallization accelerator is a component for increasing the crystallinity of the polyester resin and improving the appearance and feel of the polyester resin composition.

As crystallization accelerators, metal salts of Group 1a or Group 1Ia of the periodic table of organic carboxylic acids, benzoic acid esters or esters of benzoic acid derivatives, fatty acid esters, and ions are effective as crystal nucleating agents for polyester resins. Examples include metal salts of copolymers, inorganic powders that are effective as crystallization promoters, and specific examples include sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, and stearic acid. Sodium, potassium stearate, calcium stearate, sodium octacosanoate, calcium octacosanoate, sodium benzoate, potassium benzoate, calcium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, ethylene glycol monobenzoate, ethylene glycol dibenzony ]
・Propylene glycol heptanobenzoate, propylene glycol dibenzoate, neopentyl tarycol monobenzoate, diethylene glycol sichhenzoate, triethylene glycol dibenzoate, ethylene glycol propylene glycol dibenzoate, ethylene-sodium acrylate copolymer, ethylene- Sodium methacrylate copolymer, talc, titanium oxide,
Zinc oxide etc. and combinations thereof can be used.

These crystallization promoters further include compounds that improve the crystallization rate when used in combination with them, such as polyoxyethylene derivatives and epoxy compounds.

It is also possible to add sorbitan derivatives and the like.

The content of the crystallization accelerator is 0.001 to 10 parts by weight per 100 parts by weight of the polyester resin. If it exceeds 10 parts by weight, the polyester resin deteriorates significantly and molding becomes difficult, which is undesirable. If it exceeds 0.001 parts by weight, the degree of crystallinity will be low, and the molded product will have poor appearance and poor feel. It becomes bad.

The specific gravity of the polyester resin composition of the present invention after molding is 1.
60 or more, preferably 1.65 or more.

If the specific gravity of the composition is less than 1.60, it is not preferable because a tone similar to that of ivory cannot be obtained and the composition lacks the heavy weight characteristic of ivory.

The polyester resin composition of the present invention includes, for example, polyester resin, resin, fibrous filler, average particle size of 50p, m
It is obtained by weighing and blending the following fluorine resin powder and crystallization accelerator in predetermined amounts, and then uniformly mixing them.

The polyester resin, fibrous filler, fluororesin powder, and crystallization accelerator can be mixed by a known method, for example, by loading the weighed mixture described above into a V-type tumbler, double cone-type tumbler, Nauta mixer, etc. Mixing methods can be used.

The polyester resin composition of the present invention is usually heat-formed and provided as a pellet-shaped molding material that is easy to handle. A known single-screw or twin-screw extruder can be used for heat shaping.

The cylinder tip head pressure of the extruder is preferably 20 k
g/i or more, and the ejection outlet resin temperature is 350°C or less, preferably 260 to 320°C. The polyester resin composition of the present invention obtained under such conditions usually has a specific gravity of 1.60 or more. At that time, a stabilizer against heat and light, a mold release agent to improve mold release properties during injection molding, and a dye pigment to produce an ivory color can be added as necessary. Ivory color can be easily obtained using chromatic pigments, brown or red pigments, white pigments, and black pigments, but the amounts used are determined depending on the application.

Further, the above pelletized composition can be molded into any shape using a common injection molding machine. that time,
Ivory products are often molded products with thick walls, so special considerations are required for injection molding. That is, it is preferable that the mold temperature is 80°C or higher, the gate is wide, the injection time is long, and the injection pressure is 55°C or higher than the short shot pressure.
It is necessary to take precautions such as increasing the pressure to 0 kg/d or higher and immediately immersing the molded product in hot or cold water after taking it out. Furthermore, when a molded product is annealed at a temperature higher than the mold temperature, the quality of the molded product tends to improve.

The polynisnal resin composition of the present invention is fiber-reinforced with a fibrous filler having high tensile strength and elastic modulus, so it has excellent mechanical properties, high abrasion resistance, and high coefficient of restitution in the event of a collision.
Furthermore, the acoustic properties are good. In addition, since it contains fluorine resin powder, it has an ivory-like appearance and feel, and has the effect of further improving wear resistance.Also, since the base material is highly crystalline polyester resin, the matrix It has excellent mechanical properties, wear resistance, and heat resistance, and its appearance, such as luster and luster, is similar to ivory.Furthermore, since it is a thermoplastic resin, it can be molded using conventional injection molding and extrusion molding methods. As a result, the polyester resin composition of the present invention has excellent mass productivity, and its molded products are inexpensive.

Hereinafter, the present invention will be explained in detail along with implementation details.

1 to 4 Polyethylene terephthalate with an intrinsic viscosity [η] of 0.80, fiber diameter 1 OpI1. Chopped strands with a fiber length of 3 mm, polytetrafluoroethylene powder with an average particle size of 3JLI11, and sodium stearate were blended in nine quantitative ratios shown in the following table, and then placed in a double cone tumbler and mixed for 5 minutes. A polyester resin composition of the present invention and a comparative composition were obtained.

Next, these compositions were put into a single-screw extruder with a screw of E15 mmφ, l, /D = 38 at a pressure of 30 to 70 kg/cn, a screw rotation speed of 8 Orpm, and an ejection outlet resin temperature of the temperature shown in the table. After extrusion, the extruded strands were cut and shaped into pellets. The specific gravity of the shaped polyester resin composition of the present invention is 1.60.
That was it. The specific gravity of these compositions is shown in the following table.

Next, these pellets were processed into a Nippon Steel injection molding machine N-1.
40BII, and using a mold that can simultaneously mold ASTM No. 1 dumbbell specimens and Izotsu specimens, the cylinder temperature was 270°C, the molding cycle was 45 seconds, and the mold temperature was 140°C. Izot specimens were molded.

The resulting molded product was tested for its appearance, feel, and tone. For the tone test, one end of the ASTM No. 1 dumbbell specimen was firmly fixed, and the other end was a 10 mm piece made of ivory.
Evaluation was made by the sound produced when lightly tapped with a φ stick. In addition, a tensile test was conducted using an ASTM No. 1 dumbbell specimen.
An Izot impact test was conducted using an Izot specimen to determine the mechanical properties of the molded product. These results are summarized in the table below.

The appearance, feel, and tone tests were conducted by comparing the ivory products as a standard and classifying these characteristics into the following three categories: O1Δ and ×.

Continuation of page 1 0 shots Akira Ishii Hiroshi 2nd division 2-3-19 Kyobashi, Chuo-ku, Tokyo Mitsubishi Rayon Co., Ltd.

Claims (1)

[Claims] 100 parts by weight of polyester resin, fibrous filler 30-1
40 parts by weight, 3 to 80 parts by weight of fluororesin powder with an average particle size of 50 pm or less, and 0.001 to 10 parts by weight of a crystallization promoter, and has a specific gravity of 1.60 or more after molding. Polyester resin composition.