JPS61283651A - Polyester resin composition and key top part using same - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having improved sliding characteristics and impregnation-printability, by blending a crystallization promoter, a polyester elastomer and a salt of an olefin/(meth)acrylic acid copolymer with a polyester resin. CONSTITUTION:0-9pts.wt. crystallization promoter (A), 0-36pts.wt. polyester elastomer (B) and 1-36pts.wt. Na or K salt (C) of an olefin/(meth)acrylic acid copolymer are blended with 100pts.wt. polyester resin (D). As component D, those composed of at least 80wt% ethylene terephthalate or butylene terephthalate unit are preferred. Examples of component A are esters of benzoic and fatty acids. Examples of component B are elastomers composed of a block copolymer consisting of a residue of an arom. Polyester as a hard segment and a residue of a polyalkylene glycol as a soft segment. As component C, Na salt of ethylene/methacrylic acid copolymer is preferred. A key top part made of said compsn. has good feeling to touch.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a polyester resin composition and a key top part molded using the polyester resin composition, and more specifically, to a polyester resin composition having excellent sliding properties and impregnation printing properties, and a key top part molded using the polyester resin composition. The present invention relates to a key top part molded from the composition having excellent sliding properties and good key feel. [Problems to be solved by conventional techniques and inventions] Conventionally,
Two-color molding has been the mainstream printing method for plastics, but recently impregnation printing has come into practical use, allowing even complex characters and shapes to be displayed directly on resin. However, this impregnation printing method requires 1
Since the dye is sublimated and transferred to the resin in an atmosphere at a temperature of 50 to 180°C, if this method is used to print ABS or polyacetal resin, which has low heat resistance, the resin may be deformed by heating. For this reason, polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin, which have excellent heat resistance, that is, excellent impregnation printing properties, have attracted attention. In addition to heat resistance, polyester resin also has mechanical properties,
Due to its excellent electrical properties and chemical resistance,
It has wide applications in electrical and electronic fields. Particularly in the field of key top parts, polyester resin is attracting attention due to its excellent properties. However, when polyester resin is used as the key top material, in a 20 million keystroke test with the polyester resin key top and bearing,
Since both the polyester resin key top component and the bearing wear out, there is a problem in that the feel of the keys becomes poor due to debris from the wear. Therefore, polyacetal resin is often used in sliding parts of rotating parts and the like instead of polyester resin, which has slightly inferior sliding properties. However, as described above, this resin has the drawback of poor heat resistance, so it has not been possible to manufacture impregnated printed key top parts. Therefore, there is currently a strong desire to develop a resin material that has both excellent impregnation printability and sliding properties. [Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have conducted extensive research and have developed a polyester resin composition that has excellent sliding properties and impregnation printing properties, as well as impregnation printing properties and We have found a key top part with excellent key top feel and have completed the present invention. That is, the present invention provides (A) 100 parts by weight of polyester resin, (B) 0 to 9 parts by weight of crystallization promoter, (C) 0 to 36 parts by weight of polyester elastomer, and (D) olefin and acrylic acid. Alternatively, by providing a polyester resin composition containing 1 to 36 parts by weight of a sodium salt or potassium salt of a copolymer with methacrylic acid, and a key top part formed by molding the polyester resin composition. be. The polyester resin (A) used in the present invention is obtained by a condensation reaction in which terephthalic acid or its ester-forming derivative (acid component) and diols or its ester-forming derivative (diol component) are the main reaction components. Polymers, copolymers, etc. As a copolymer, one in which 30% or less of the acid component is usually replaced with another copolymer component, such as isophthalic acid or cyclohexanedicarboxylic acid, can be used. Acid components include phthalic acid, isophthalic acid, adipic acid,
Mention may be made of sebacic acid, naphthalene dicarboxylic acid, anthracene dicarboxylic acid, cyclohexane dicarboxylic acid, etc. and mixtures thereof. Diol components include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, hydroquinone, resorcinol, 2.2-bis (4-hydroxyphenyl) propane, bis (4-hydroxy). phenyl) sulfone, etc. and mixtures thereof. Particularly preferably, the copolymer contains 80% by weight of ethylene terephthalate units or butylene terephthalate units.
This is a polyester resin containing the above. The intrinsic viscosity [η] of the polyester resin is usually 0.4 or more, preferably 0.5 to 1.8.

If [η] is lower than 0.4, sufficient strength will not be obtained and the product will be easily damaged, which is undesirable. On the other hand, if [η] is too high, the screw rotation torque during injection molding will increase and the screw will stop. In addition, the surface appearance of the obtained molded product may deteriorate. Therefore, in practical terms, the upper limit of the intrinsic viscosity is 1.6. Here, the intrinsic viscosity [η] refers to a value determined from the solution viscosity measured at 25° C. in a phenol/tetrachloroethane=50150 (weight ratio) solvent. Polyester resin (A) serves as a standard for the amount of other (B) to (D) components, and polyester resin (A)
) is 100 parts by weight. The crystallization accelerator (B) is not particularly limited, but includes, for example, metal salts of Group Ia or Group 1Ia of the periodic table of organic carboxylic acids that are effective as crystal nucleating agents for polyester resins, benzoic acid esters, or benzoic acid. derivative ester,
Examples include fatty acid esters, metal salts of ionic copolymers, and inorganic powders that are effective as crystallization promoters. Specifically, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium stearate, potassium stearate, calcium stearate, sodium octacosanoate, calcium octacosanoate, sodium benzoate, benzoic acid. Potassium, calcium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, ethylene glycol monobenzoate,
Ethylene glycol dibenzoate, propylene glycol 7nopenzoate, propylene glycol dibenzoate, neopentyl glycol monobenzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate, ethylene glycol propylene glycol dibenzoate, talc, titanium oxide, zinc oxide, etc. Combinations can be used. These crystallization promoters may further contain compounds that can improve the crystallization rate when used in combination with them, such as polyoxyethylene derivatives, epoxy compounds, sorbitan derivatives, and the like. The amount of the crystallization accelerator to be blended is in the range of 0 to 9 parts by weight based on 100 parts by weight of the polyester resin (A). In this case, if the blending amount exceeds 8 parts by weight, the polyester resin deteriorates and molding becomes difficult, which is not preferable. The polyester elastomer (C) includes (1) an elastomer made of a block copolymer with aromatic polyester residues as hard segments and polyalkylene gellicol residues as soft segments, (2) crystalline aromatic Examples include an elastic body made of a block copolymer having polyester residues as hard segments and polylactone residues as soft segments. The aromatic polyester residues mentioned in (1) include polyethylene terephthalate, polybutylene terephthalate,
Examples include polyethylene terephthalate isophthalate, polyethylene paraoxybenzoate, polyethylene terephthalate adipate, polyethylene terephthalate sebacate, polyethylene naphthalate, polybutylene terephthalate adipate, polybutylene terephthalate isophthalate, polybutylene terephthalate and ethylene terephthalate residue, etc. . Examples of the polyalkylene glycol residues include polytetramethylene glycol, polyethylene glycol, polyethylene glycol/polypropylene glycol block copolymers, and polyhydric alcohol/alkylene oxide adduct residues. The elastic body has a molecular weight of 8
50 or more, preferably 800 to 8,000 polyalkylene glycol is used, and the polyalkylene glycol portion is 20% by weight or more, preferably 30 to 80% by weight.
It is usually an aromatic polyester-polyalkylene glycol block copolymer having a glass transition temperature of 10° C. or less, preferably -15° C. to -80° C., and a molecular weight of to, ooo or more, preferably 30,000 or more. The method for preparing this copolymer involves polymerizing polyalkylene glycol using a relatively low molecular weight (molecular weight 500 to 5000) crystalline aromatic polyester as an initiator, and then extending the chain with a polyfunctional acylating agent. Alternatively, a crystalline aromatic polyester with a relatively high molecular weight (preferably a molecular weight of 5000 or more) and a polyalkylene gellicol are heated and dissolved to form a block copolymer. Examples of methods include: The crystalline aromatic polyester residue mentioned in (2) is:
For example, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, poly-
Homopolyesters such as 1,4-cyclohexylene dimethylene terephthalate, polyethylene-2,8-naphthalate, polyethylene oxydibenzoate, poly-p-
Polyester ethers such as phenylene hisoxyethoxy terephthalate, mainly consisting of alkylene terephthalate units, and also ethylene isophthalate units, ethylene adipate units, 1,4-cyclohexylene dimethylene terephthalate units, ethylene 7-Pr+dibenzoate units, etc. Examples include copolyester or copolyester ether residue containing a copolymer component at a ratio of 20 mol % or less, and polybutylene terephthalate is particularly preferred. In addition, as polylactone residues, ε-caprolactone,
Enantolactone, caprolactone residues, etc. can be mentioned. These can be used alone or in a mixed system of two or more. Among these, ε-caprolactone is preferred. In this case, the blending ratio of crystalline aromatic polyester residue and polylactone residue is 20/80 to 90/
10, preferably 40/80 to 80/20
It is. Further, the melting point of the copolymer is preferably 170°C or higher. Such a copolymer has a relatively low molecular weight (molecular weight 500 to 5
A method of polymerizing lactones using a crystalline aromatic polyester of It can be produced by a method such as a method of heating and dissolving a crystalline aromatic polyester (preferably 5,000 or more) and lactones and reacting them to form a block copolymer. The blending ratio of (1) and (2) in the composition is 0 to 36 parts by weight, preferably 2 to 18 parts by weight, based on 100 parts by weight of the polyester resin (A). The blending ratio is 3
If the amount exceeds 6'ifX parts, the heat distortion temperature decreases, which is not preferable. Furthermore, component (D) in the present invention is a sodium or potassium salt of a copolymer of an olefin and acrylic acid or methacrylic acid, and the olefin is usually 50% of the copolymer.
-98% by weight, preferably 80-98% by weight, and 30% or more of the total carboxylic acid residues are neutralized with sodium or potassium, and a particularly preferred substance is sodium ethylene/methacrylic acid copolymer. It's salt. The mixing ratio thereof is in the range of 1 to 36 parts by weight, preferably 3 to 27 parts by weight, based on 100 parts by weight of the polyester resin (A). When the blending amount exceeds 36 parts by weight, the heat deformation temperature decreases significantly, the compatibility with the polyester resin decreases, and the strength decreases. Furthermore, if it is less than 1 part by weight, the effect of improving sliding properties will not be noticeable. The polyester resin composition of the present invention may contain various stabilizers such as ultraviolet absorbers, antioxidants, and heat deterioration inhibitors, dyes and pigments, and various additives such as matting agents without departing from the purpose of the present invention. Can be blended. The polyester resin composition of the present invention includes, for example. A polyester resin (A), a crystallization accelerator (B), a polyester elastomer (C), and a sodium salt or potassium salt (D) of a copolymer of olefin and acrylic acid or methacrylic acid are added, and a tumbler, etc. The mixture can be obtained by mixing in a suitable mixer, feeding the mixture into an extruder, etc., and performing melt cross-extrusion to form pellets. Applications of the polyester resin composition of the present invention are not particularly limited, but specific examples include key top parts for office automation equipment, flywheels for VTRs, impedance rollers, gears for cassette tapes, gears for video tapes, bearing retainers, Various uses such as bearings are possible. Among these various uses, the polyester resin composition of the present invention is particularly useful for molding key top parts. The key top parts referred to herein are parts including keyboards and their bearings of various office automation equipment, personal computers, smartphones, computer terminals, desktop electronic calculators, etc., or buttons of various equipment. The key dope/pu part according to the present invention is molded using the above-mentioned polyester resin composition according to the present application. This key top part can be obtained, for example, by a method of molding the above pelletized polyester resin composition into a key top part of a predetermined shape using an injection molding machine. EXAMPLES Below, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in Examples and Comparative Examples, all "parts" represent "parts by weight". [Examples of the invention] Examples 1 to 12 (A) Polyester resin, (B) Crystallization promoter, (C)
As each component of the polyester elastomer and (D) the sodium salt or potassium salt of the copolymer of olefin and acrylic acid or methacrylic acid, those shown in Table 1 are used,
These were blended at the blending ratio shown in Table 1.
The mixture was mixed in a mold blender for 5 minutes to obtain a polyester resin composition of the present invention. Using this composition, a test piece was molded in the following manner, and an evaluation test was conducted using the test method and conditions described below. The results are shown in Table 1. (1) Production of pellets The composition was formed into pellets by extrusion using a 65 mm diameter vented melt extruder (manufactured by Isuzu Kakoki ■) at a cylinder temperature of 250 to 260°C. (2) Molding of evaluation test piece 1) The pellets produced in (1) were injection molded using 4!1 (manufactured by Jumite Heavy Industries, trade name: Neomat Nl50/75) at a cylinder temperature of 260°C to 270°C, and Mold temperature 80
ASTM D-790 bending strength test piece (!2°7X 127X3.2t) and AST
A test piece (ff3×12.7×3.2) of MD-258 with Izod impact strength (with /titch) was molded. 11) Under the same injection conditions as in 1) above except that a different mold was used, pellets manufactured in (+) weighed 3.6
A thrust wear test ring (inner diameter: 19 layers, outer diameter: 251 layers, height: 1511 layers) was molded. (2) Using the pellets produced in (1), a flat plate of toox ioo x at was molded in order to conduct an environmental test after impregnation printing. (3) Evaluation test Bending strength test: Using the test piece molded in (2), the crosshead speed was 1.5 m using Tensilon 5t UT'M-115000 (Toyo Poldouia Co., Ltd. V).
Tested at m/zen. Izot impact strength test: Using the test piece molded in (2), it was tested with U-F IWpAcTTESTER (Ni-F I7 Bact Tester, manufactured by Kaminou Seisakusho). Thrust wear test = using the test piece molded in (2),
Thrust wear tester (Toyo Baldwin, EFM-I
[[-E type] was used to evaluate the sliding properties under the following conditions. (Test conditions) Load: 1.4 kg Slip speed: 80 mm/sec Travel distance: 7000 m Companion agent Modified PPO resin (Noryl 90J) J9! The wear coefficient and specific wear amount were calculated according to the following formula. - Condolences Todoroki A special ink containing sublimable dye crystals kneaded into a base resin was used to transfer and coat a printed pattern onto a plastic film. Coated release paper (2)
Place it on a flat plate formed with
The dye in the ink was vaporized at 0°C and a pressure of 0.1 kg/c for 112.20 sec), and printing was performed on a flat plate. The above impregnated printed plate was placed in an oven at 60°C for 72 hours.
After leaving it for a while, the state of bleeding in the print was visually observed. The test results are shown in Table 1. In Table 1, O means that there is no bleeding in printing, Δ means that there is some smearing, and × means that there is some smearing of 1/s. Comparative Examples 1 to 4 Pellets were obtained in the same manner as in Example 1, except that the composition and blending ratio were changed as shown in Table 1. Using this pellet, a test piece was molded in the same manner as in (2) above, and the same evaluation test as in Example 1 was conducted. The results are shown in Table 1. Examples 13 to 24 (1) Molding of key tops Polyester resin pellets produced in the same manner as in Example 1 were molded using an injection molding machine (manufactured by Jujuki Co., Ltd., trade name: Neomat 'N15).
0/75), a 16-cavity key top mold was used, the cylinder temperature was 260°C to 270°C, and the molding cycle was 2.
A key top part weighing 1.5 g was molded for 0 seconds at a mold temperature of 80°C to 100°C. (2) Evaluation Test Keytop Test A keytop component typing test was conducted under the following conditions to examine the feel of the keytop components. Table 2 shows the feel of the key top after 20 million keystrokes at a load of 120 g and 10 Hz. In addition, Table 2
Among them, ■ indicates a very good feel, and O indicates a slightly good feel. X represents a bad feel. - An environmental test of impregnation printing was conducted in the same manner as in Example 1 to examine the performance of impregnation printing. The test results are shown in Table 2. In Table 2, 0, Δ and × have the same meanings as in Example 1. Thrust. The weight was 3.8 using the beret molded in Example 1 under the same injection conditions as above, except that a different mold was used.
A thrust wear test ring (inner diameter 19 layers, outer diameter 25a+m, height 15m layers) was molded. Next, a thrust wear test was conducted using the same thrust wear tester as in Example 1 under the same conditions as in Example 1, and the results are shown in Table 2. The wear coefficient and specific wear amount are as in Example 1.
Calculated in the same way. Comparative Examples 5 to 8 As shown in Table 2, key dopes were molded in the same manner as in Example 13, except that the composition and blending ratio were changed. The obtained key top component was subjected to the same evaluation test as in Example 13. The results are shown in Table 2. However, in components (C) and (D) in Tables 1 and 2, (a): polybutylene terephthalate/polytetramethylene glycol block copolymer, polytetramethylene glycol molecular weight 2,000° butylene terephthalate: polyether = 4 = 1 Mol (Tg = -sa°C, molecular weight 45,000) (b): polyethylene terephthalate/polytetramethylene glycol block copolymer, polytetramethylene glycol molecular weight 1,000° ethylene terephthalate: polyether = 4: 1 mole (Tg = -34°C, molecular weight 40,000) (c): Polybutylene terephthalate/polycaprolactone block copolymer PBT segment/polycaprolactone segment = weight ratio 7/3 Melting point 215°C (d): Polyethylene terephthalate/polycaprolactone block copolymer Polymer PET segment/polycaprolactone segment = weight ratio 515 Melting point 210°C (E): Ethylene/methacrylic acid copolymer (85/15
) 60% by weight neutralized with sodium (to): ethylene/acrylic acid copolymer (85/15)
Neutralization of 65% by weight with potassium [Effects of the Invention] As detailed above, the polyester resin composition of the present invention has a cured product having excellent impregnation printing properties and sliding properties in a well-balanced manner. Therefore, its industrial value is great in various fields including key top parts. Furthermore, the key parts molded using the above polyester resin composition also have particularly excellent impregnating properties and tactile feel when pressed, and have great industrial value like the polyester resin composition. .

Claims (1)

[Claims] 1. (A) With respect to 100 parts by weight of polyester resin, (
B) 0 to 9 parts by weight of crystallization accelerator, (C) 0 to 36 parts by weight of polyester elastomer, and (D) 1 to 36 parts by weight of sodium or potassium salt of a copolymer of olefin and acrylic acid or methacrylic acid. A polyester resin composition comprising: 2. (A) For 100 parts by weight of polyester resin, (
B) 0 to 9 parts by weight of crystallization accelerator, (C) 0 to 36 parts by weight of polyester elastomer, and (D) 1 to 36 parts by weight of sodium or potassium salt of a copolymer of olefin and acrylic acid or methacrylic acid. A key top part characterized by being formed by molding a polyester resin composition containing parts.