JPH072899B2 - Polyester resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition which is excellent in long-term friction and wear characteristics and which can provide a sliding component having a small frictional noise when sliding. More specifically, it relates to a polyester resin composition obtained by blending a thermoplastic polyester resin with a silicone oil having a viscosity of 700,000 cSt (centistokes) or more.

[0002]

2. Description of the Related Art Thermoplastic polyester resins such as polybutylene terephthalate and polyethylene terephthalate are excellent in mechanical properties, electrical properties, heat resistance, chemical resistance and the like, and also have processability. Since it is good, it has been used as an engineering resin in an extremely wide range of fields in recent years. With the expansion of such fields of application, these resins tend to be used under more severe conditions, and more advanced properties are required for the resins in many cases. As one of these properties, in the field of sliding parts, mechanical parts, etc. of automobiles, electric / electronic products, etc., the friction and wear characteristics are further improved, and their long-term sustainability or friction noise accompanying sliding May be required to be reduced. Conventionally, as a method of improving the friction and wear characteristics of the thermoplastic polyester resin, for example, (1) a method of adding a solid lubricant such as molybdenum disulfide, graphite, (2) powder or fibers of polytetrafluoroethylene resin A method of adding, (3) a method of adding a liquid or semi-solid lubricant such as a petroleum-based lubricating oil, a synthetic lubricating oil, an aliphatic alcohol or its ester, and the like are known. Known from the past,
Even with these methods, the friction and wear characteristics are of course improved, and in many cases, especially in the case of short-term use under low-speed, low-load sliding conditions, the requirements can often be satisfied, but high-speed,
Friction characteristics become insufficient under high load sliding conditions, and friction characteristics drastically decrease with the passage of sliding time even under low speed and low load, resulting in lack of long-term stability and reliability. There is a problem. Further, as a method of improving the frictional noise during sliding, a method of blending polyethylene, polytetrafluoroethylene or the like to soften the resin is generally used.
There is a problem that the sound deadening property that can meet the demand is not always obtained and the physical properties such as mechanical strength are deteriorated. As described above, in the conventionally known method, frictional wear characteristics, particularly high speed,
In terms of characteristics under a high load condition, long-term characteristics, and also in terms of sound deadening characteristics during sliding, it is not possible to meet strict requirements, and improvements thereof are earnestly desired.

[0003]

Means for Solving the Problems The present inventors have solved these problems, improved the long-term friction and wear characteristics without deteriorating the excellent physical properties originally possessed by the thermoplastic polyester resin, and As a result of extensive studies on a method of reducing the frictional noise during movement, the present invention was found to be that the addition of silicone oil having a specific viscosity is extremely effective. That is, the present invention is a thermoplastic polyester resin 9
Provided is a polyester resin composition comprising 9.9 to 80.0 parts by weight and 0.1 to 20 parts by weight of a silicone oil having a viscosity of 700,000 cSt (centistokes) or more.

The thermoplastic polyester used in the present invention is a polyester obtained by polycondensation of a dicarboxylic acid compound and a dihydroxy compound, polycondensation of an oxycarboxylic acid compound, polycondensation of a mixture of these three components, a homopolyester, The effect of the present invention is exerted on any of the copolyesters. Examples of the dicarboxylic acid compound used here include known dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid and sebacic acid. Examples thereof include acid compounds and their alkyl, alkoxy or halogen substitution products. Also, these dicarboxylic acid compounds can be used in the form of a derivative capable of forming an ester, for example, a lower alcohol ester such as dimethyl ester. In the present invention, one kind or two or more kinds of the above compounds are used. Next, examples of dihydroxy compounds are ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hydroquinone, resorcin, dihydroxyphenyl, naphthalenediol, dihydroxydiphenyl ether, cyclohexanediol, 2,2'-bis (4-hydroxyphenyl). ) Dihydroxy compounds such as propane and their alkyl, alkoxy or halogen-substituted compounds, etc., and one kind or a mixture of two or more kinds can be used. Examples of the oxycarboxylic acid include oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid, and diphenyleneoxycarboxylic acid, and alkyl, alkoxy or halogen substitution products thereof. Further, ester-formable derivatives of these compounds can also be used. In the present invention, one of these compounds
One kind or two or more kinds are used. In the present invention, any of the thermoplastic polyesters produced by polycondensation can be used as the monomer component of the compound as described above, and they can be used alone or in combination of two or more, and preferably polyalkylene terephthalate. , And more preferably, polybutylene terephthalate is used, and the effect of the present invention is remarkable. Further, in the present invention, the thermoplastic polyester may be modified by a known method such as crosslinking or graft polymerization.

In the present invention, the silicone oil blended with the polyacetal resin as described above means dimethylpolysiloxane or a part of the methyl group thereof is hydrogen, phenyl group, halogenated phenyl group, halogenated alkyl group, fluoroester. It is one or more substituted with a group such as a group and has a viscosity of 700, measured by ASTM D-445,
A material having an extremely high viscosity of 000 cSt (25 ° C) or higher is used. Silicone oils with lower viscosity than this, especially
With silicone oil of 100,000 cSt or less,
Although the initial friction and wear characteristics are improved, it is not possible to sufficiently improve the long-term friction and wear characteristics or the friction noise during sliding, which is the object of the present invention, and the viscosity is higher than 300,
A silicone oil of about 000 cSt satisfies the above characteristics to some extent, but does not particularly satisfy the sliding characteristics under a high load. Conversely, a rubbery silicone resin with a high degree of polymerization may be dispersed uniformly in the resin. It is extremely difficult, and not only the improvement of friction and wear characteristics cannot be expected, but also mechanical properties and the like may be impaired, which is not preferable. More preferably 1,000,
A material having a viscosity of 000 cSt or more is used. Further, in the present invention, 0.1 to 20 parts by weight of such silicone oil is added to 99.9 to 80 parts by weight of polyester resin. If the amount is smaller than this, sufficient improvement in frictional wear characteristics cannot be obtained, and conversely, if the amount is larger than this, the workability and mechanical properties may be significantly deteriorated, which is not preferable. Therefore, it is preferable to blend in the range of 0.3 to 10 parts by weight in consideration of the balance of short-term and long-term friction and wear characteristics, other various physical properties and workability. Further, in the present invention, it is also possible to add such silicone oil by diluting it with a solvent or the like, or by adsorbing it on an inorganic or organic solid, and improving the workability of adding silicone oil or the dispersibility of silicone oil. It is often preferable from the aspect. It is also preferable to use a dispersant in combination so as to improve the dispersion of the silicone oil in the resin. The reason why such a high-viscosity silicone oil of the present invention provides excellent long-term friction and wear characteristics and sound deadening characteristics is not necessarily clear, but the inventors of the present invention speculate that such a high-viscosity silicone oil It forms a stable coating that does not easily peel off on or near the surface of the resin, so that the effect is considered to continue. On the other hand, low-viscosity silicone oil easily bleeds onto the resin surface, so it has good initial friction characteristics, but its low viscosity (low degree of polymerization) makes it easy to peel off and remove it, and thus with the passage of sliding time. It is considered that the friction characteristics are deteriorated.

In the composition of the present invention, solid lubricants such as graphite, molybdenum disulfide, and metal soap, polyethylene resins, polytetrafluoroethylene resins, and the like have good lubricity for the purpose of further improving sliding characteristics. It is also possible to blend a polymer or the like that can be applied. Further, in order to improve the physical properties depending on the purpose, various known additives may be further added. Examples of additives include antioxidants, weathering / light resistance stabilizers, heat resistance stabilizers, lubricants, release agents, nucleating agents, silicone oil dispersants, antistatic agents, flame retardants, and colorants. In addition, the composition of the present invention may be added with a fibrous, plate-like, or granular inorganic filler such as glass fiber depending on the purpose, and additionally, other resin or polymer substance may be supplementarily added and commonly used. Of course, it is also possible. The composition of the present invention can be easily prepared by a known method generally used as a conventional resin composition preparation method. For example, after mixing each component, kneading and extruding with a single-screw or twin-screw extruder to prepare pellets, and then forming, pellets having different compositions are prepared once, and the pellets are mixed in a predetermined amount. Can be used for molding to obtain a molded product of the desired composition after molding, and a method of directly charging one or more of each component into a molding machine.

[0007]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 7 and Comparative Examples 1 to 8 Polybutylene terephthalate resin [manufactured by Polyplastics Co., Ltd., trade name "Duranex 2000"] has a viscosity of 700,
Various silicone oils of 000 cSt or more were added and mixed at a ratio shown in Table 1, and then melt-kneaded by a twin-screw extruder to prepare a pelletized composition. Next, using the pellets, test pieces were prepared by injection molding and evaluated. For comparison, as shown in Table 2, the same evaluation was performed for the sample to which silicone oil was not added and the sample to which silicone oil having a viscosity outside the scope of the present invention was added. The results are also shown in Tables 1 and 2. The sliding characteristics were evaluated by the following method, and the tensile characteristics were measured according to the ASTM measuring method. Dynamic friction characteristics Using a Suzuki type friction and wear tester, pressing force 0.75kg / cm ² , linear velocity 180mm / sec, contact area 2.0cm ² , mating material ABS resin,
The coefficient of dynamic friction was measured immediately after the start of sliding and after sliding for 60 minutes. In addition, the time until the coefficient of dynamic friction (μd) rises to 0.2 was determined as one measure of stability. Friction noise characteristics Using the above tester, pressure force 3.5kg / cm ² , linear velocity 50mm / s
The generation of squeaking noise was evaluated while sliding the same material for 10 hours with ec and a contact area of 2.0 cm ² . Sliding characteristics under high load Using Suzuki type friction and wear tester, load 5kg, linear velocity 200mm /
In sec, the polyester resin cylinder (φ10mm × 10mm) side surface and the flat surface of the test material Suzuki type test piece are line-contacted in 24
After sliding for 24 hours, the coefficient of friction after 24 hours and the wear amount of the Suzuki type test piece were obtained.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

As is clear from the above description and examples, by blending a thermoplastic polyester resin with a silicone oil having a viscosity of 700,000 cSt or more, long-term friction and wear characteristics, frictional noise during sliding, etc. There is no inconvenience that the various properties are remarkably improved and the other physical properties are substantially deteriorated to a problem. As described above, the composition of the present invention has well-balanced and excellent properties, and is a sliding member in the fields of automobiles, electric / electronic devices, office machines, sundries, etc., such as gears, bearings, keyboards. It is preferably used as a component.

Claims (3)

[Claims] 1. A polyester resin composition comprising 99.9 to 80.0 parts by weight of a thermoplastic polyester resin and 0.1 to 20 parts by weight of a silicone oil having a viscosity of 700,000 cSt (centistokes) or more. 2. The polyester resin composition according to claim 1, wherein the thermoplastic polyester resin is polyalkylene terephthalate. 3. The polyester resin composition according to claim 1, wherein the thermoplastic polyester resin is polybutylene terephthalate.