JPS6038580B2 - silent gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to galaxies obtained from POIJ ester ether flock copolymers.

More specifically, the present invention relates to a noise-free gear obtained from a polyether ester floc copolymer containing terephthalic acid, ethylene glycol, and poly(oxyalkylene) glycol as the main constituents. Conventionally, metals, synthetic resins, rubbers, and the like have been widely used as materials for gears. However, although metal gear is inexpensive as a material, it produces a so-called metallic sound when used, and when incorporated into a device, the weight of the device itself becomes heavy, which poses a significant problem when moving the device. PoIJ acetal resin seems to be the most commonly used synthetic resin material, and is an excellent material, but gears made from it make noise when driven, and their uses are severely limited. Boriacetal resin gas generates noise, so a silent synthetic resin material such as nylon-6 with molybdenum sulfide has been proposed and used, but the generation of noise is still unavoidable. Thermoplastic polyurethane is also available as a material that generates less noise. However, as is well known, this material has very poor injection moldability and a low molding yield, and the quality of the molded products is inconsistent, such as some molded products being transparent but others devitrified. has significantly reduced the product value. Rubber compositions have been improved and hard materials are used in some gears, but as is well known, the processing process is extremely long and burrs are likely to occur during molding. Generally speaking, the more flexible these materials are, the less noise they produce, but in this case, the gear's ability to transmit the power that is originally required will be reduced.

The inventor of the present invention aims to minimize the decrease in power transmission force,
As a result of intensive research into materials that can reduce noise generation and are easy to mold, we found that sound generation depends on the surface hardness measured with a durometer, while power transmission characteristics depend on the bending elastic modulus. I found out what to do.

As a result of repeated studies to find a material with a high flexural modulus of elasticity and low surface hardness, we found a polyether ester material whose main components are terephthalic acid, ethylene glycol, and poly(oxyalkylene) glycol. Made from flock copolymer, the surface hardness of the molded product is 30 on the durometer D scale.
It was discovered that a product molded to have a molecular weight in the range of 75 to 75 satisfies these characteristics, leading to the present invention.
That is, the present invention provides a substantially noiseless gear made of a thermoplastic elastic polymer, which has an average molecular weight of 350 to 5,000 and a carbon number to oxygen ratio of 2.0 to 4.
．． It consists of an ether ester unit ■ consisting essentially of poly(oxyalkylene) glycol and terephthalic acid in a ratio of 5:1 and an ester unit 'B} consisting essentially of ethylene glycol and terephthalic acid; A silent gear comprising a polyester ether flock copolymer in which the unit air accounts for 20 to 7% by weight of the whole, and the molded product thereof has a surface hardness of 30 to 75 (measured on a durometer D scale). .

The material used in this invention is a polyester block copolymer consisting essentially of intramolecular linear ether ester unit legs and ester units {B}. The polyalkylene glycols forming the ether ester units are, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol block copolymers, etc., and these have a ratio of carbon numbers to oxygen numbers. is 2.0
~4.5 and can be used alone or, of course, as a mixture.

Further, the average molecular weight thereof must be in the range of 350 to 5,000. Further, the ether ester unit and the acid component forming the ester unit are substantially terephthalic acid. In addition to terephthalic acid, other aromatic dicarboxylic acids such as isophthalic acid or adipic acid, sebacic acid, cyclohexane-1 in a proportion of up to 20 mol% of the brewing ingredients
, 4-dicarboxylic acid and the like may be used in combination. Further, the glycol component forming the ester unit leg is substantially ethylene glycol, but the proportion thereof is 20 mol% or less. Aliphatic glycols such as pyrene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neobenzene glycol, and aromatic glycols such as bisphenol A may be used in combination. Furthermore, trimethylolbropane and bentaerythritol can be added as diol components, and recovery properties are significantly improved. Therefore, the polyester ether block copolymer consisting essentially of the ether ester units (1) and the ester units (2), which are components of the block copolymer constituting the GA of the present invention, is as follows:
The etherester unit legs account for 20-7% by weight.

Among the components constituting the unit (1) and the unit (B), preferred components are terephthalic acid, ethylene glycol, and polytetramethylene glycol, which are especially excellent in moldability. Furthermore, since the ester unit is polyethylene terephthalate, the flexural modulus is higher at the same hardness than a polyester ether block copolymer whose ester unit is polytetramethylene terephthalate, which is preferable. The particularly preferable range of the ether ester unit ratio varies depending on the use of the gear, but for gears that are subjected to loads, a range of 20 to 4% by weight is preferable, and for gears that are used at low loads and at low speeds, it is preferable. A weight percent between 40 and 7 is preferred.

In any case, the applications are wide-ranging, so it is important to choose the appropriate composition according to the application, but in general there are three
0 to 65% by weight is preferably used. And those in this range are silent and mechanical properties (strength, wear resistance)
is good, and the molding cycle property is also good. In addition, a part of the wind unit is a fatty acid polyester (for example, a polyester of an aliphatic dicarboxylic acid such as adipic acid or sebacic acid and a C2 to C6 diol such as ethylene glycol, propylene glycol, tetramethylene glycol, or hexanediol). Substitution (preferably 50 mol % or less of the air units) may be performed. The above-mentioned polyester ether flock copolymer is produced by, for example, reacting dimethyl ester of terephthalic acid with polytetramethylene glycol and ethylene glycol in the presence of a transesterification catalyst, and then reducing the excess of the prepolymer obtained under reduced pressure. It is produced by distilling a molecular weight diol to form a high molecular weight polyester ether block copolymer.

Of course, it may also be produced by a direct esterification method using terephthalic acid instead of dimethyl ester of terephthalic acid.

The manufacturing method itself may be any method. In the present invention, the polyester ether block copolymer having the above-mentioned specific composition is molded to form a gap, and in this molding, the surface hardness is 30 to 75 (
Shore D scale).

In the present invention, any method may be used to mold the gear, but it is advantageous to form the gear by injection molding.

When molding, for example injection molding, a block copolymer having the above composition may
There may also be cases where it is not possible to obtain a gear molded product that does not have the desired surface hardness. If the surface hardness is outside the scope of the present invention, for example, if it is less than 3 degrees centigrade, not only will the power transmission force be extremely reduced, but even if the negative value is low, there will be a phenomenon of deformation (creep phenomenon) due to long-term use. . On the other hand, gears with a surface hardness exceeding 75 are undesirable because they generate loud noises during use. One of the methods for forming the material to have a surface hardness of 30 to 75 is to mold at a high mold temperature such as 50 to 1400C.

At this time, an operation of heat-treating the molded body may also be used. During molding, an alkali metal salt or alkali metal salt of an aliphatic monocarboxylic acid (having a carbon number of 10 to 40) is added in an amount of 0.05 to 5% by weight based on the polyester block copolymer.
It is desirable to add it and mold it. Among these metal salts, sodium salts are particularly preferred, and sodium stearate, sodium montanate, and the like are commonly used. The addition time and method are arbitrary, and examples include a method of adding it to the molten polymer during the polymerization reaction of the block copolymer or after the completion of the reaction, and a method of mixing it with a polymer chip and attaching it to the surface of the polymer chip and molding it. . As a guideline during molding, the relationship between the surface hardness of the formed body and the etherester unit of the etherester block copolymer is as follows: If the unit weight is 7% by weight, the lower limit of the surface hardness should be 30 or more, In the case of 5% by weight, it is preferably 40 or more, and in the case of 3% by weight, it is preferably 60 or more. The gear formed in this way has the advantage that it produces less noise when used, and also has the property of being difficult to transmit vibrations generated by the device, resulting in less noise from the device as a whole. , e.g. tape recorder, camera,
Used in the driving parts of movie projectors, wet-type and dry-type copying machines, and various measuring machines.

The gear of the present invention not only has these advantages, but also has little decrease in hardness and elastic modulus due to temperature changes, and also has good oil resistance.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

In the examples, "part" and "r%" indicate weight standards, and the reduced specific viscosity was measured at 3500 by dissolving sample polymer 120 in chlorophenol 10. In addition,
The surface hardness of the polymer was measured according to the following method. Surface hardness: ASTM Shore D Example 1 70 parts of dimethyl terephthalate, 462 parts of ethylene glycol, and 3 parts of polytetramethylene glycol (molecular weight approximately 800) were placed in a reactor equipped with a punch, a distiller, and a nitrogen inlet tube.
After charging 0.00 parts and 0.033 parts of tetraptoxy titanate and heating to 180 to 220o0 to produce 97% of the theoretical amount of methanol, the temperature was raised to 25,000.
and react at normal pressure for 30 minutes, then leave it for about 30 days.
ds weak vacuum for 30 minutes, and then
．． Polymerization was carried out for 200 minutes under high vacuum for 3 days.

The resulting polymer had a reduced specific viscosity of 1.64 and an ether ester unit content of 36%. Table 1 shows the results of measuring the surface hardness of this polymer. After drying this polymer in a hot air dryer at 140cc for 2 hours, it was made into a single piece with a diameter of 4 sides and a thickness of 2 in the center, and a diameter of 12 of the same circle with a thickness of 4 legs. The molded product was molded using an injection molding machine at a mold temperature of 10,000. The surface hardness of this molded article was 57.

Incorporate the obtained gear into the test drive set and rotate it.
In a room with a noise level of 45 horns, the sound level was measured at 20 skins from the gear, and it was 51 horns. Comparative Example 1 Modified polyacetal “Duracon M-9” (manufactured by Polyplastics Co., Ltd.), a composition prepared by blending nylon-6 with 5% by weight of molybdenum sulfide, and polyurethane “
Elastran 5059'' (manufactured by Nippon Elastran Co., Ltd.) was molded in the same manner as in Example 1 to obtain a gap.

The sound during use of this gear was measured under the same conditions as in Example 1, and the sound was 62 horns for the Duracon gear, 60 horns for the nylon-6 gear, and 51 horns for the Elastran gear.
It was a horn. Example 2 A polyester ether flock copolymer was produced in the same manner as in Example 1, and its ether ester unit density was 25%.
45% and 60% block copolymers (average molecular weights of polytetramethylene glycol used were 600 and 60%, respectively).
800, 1500), 0.5% by weight of Hoechst's "Hoechst Wax S" neutralized with caustic soda, dried and ground, was injection molded at a mold temperature of 6. I got it.

The generated sound and the surface hardness of the gear were measured in the same manner as in Example 1, and were as follows. Comparative Example 2 Molding in Example 1 was performed using the same polymer at a mold temperature of 25%.
When the gear was injection molded using 00, the surface hardness was 26.

Claims (1)

[Claims] 1 Gears made of thermoplastic elastic polymer that do not generate substantially sound, the material having an average molecular weight of 350 to 5
,000 and the number of carbon atoms to oxygen is 2.0 to 4.5 to 1, and an ether ester unit (A) consisting essentially of poly(oxyalkylene) glycol and terephthalic acid, and an ether ester unit (A) consisting essentially of ethylene glycol and terephthalic acid. A polyester ether block copolymer consisting of an ester unit (B) which has an ether ester unit (B), and in which the ether ester unit (A) accounts for 20 to 70% by weight of the whole, and the surface hardness of the molded product is 30 to 75. A silent gear (measured on a durometer D scale).