JP2001031862A - Polyurethane-based elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition suitable for a molding material for a packing for a sliding part, etc., having an improved service life by making the composition include a polyurethane-based elastomer and a carbon fiber. SOLUTION: This composition comprises (A) 100 pts.wt. of a polyurethane- based elastomer and (B) about 1-6 pts.wt., preferably about 2-5 pts.wt. of a carbon fiber having preferably about 30 μm to 3 mm, more preferably about 50 μm to 1 mm length and preferably about 1-50 μm, more preferably about 5-30 μm diameter. A polyester polyol, a polyether polyol, an acrylic polyol, a silicone polyol, a 1,4-polybutadiene polyol, a flame-retardant polyol, a caster oil polyol having about 500 to 3,000, preferably about 1,500 to 2,500, etc., are preferably used as the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyurethane elastomer composition. More specifically, the present invention relates to a polyurethane elastomer composition suitably used as a molding material such as packing for a sliding portion.

[0002]

2. Description of the Related Art Conventionally, packing using a polyurethane elastomer having excellent mechanical strength and abrasion resistance has been widely used as packing for a hydraulic cylinder. However, with the recent increase in speed, pressure, and temperature of apparatuses, it has become more difficult to satisfy such required life with conventional materials.

In order for the packing to maintain the initial sealing property, it is necessary to maintain an initial appropriate contact surface pressure distribution form and interference. Since the contact surface pressure distribution pattern mainly changes with wear, and the interference varies with wear and set, the life of the sliding packing depends on wear and set.

[0004] As a method of suppressing wear, a method of adding a filler is generally performed. However, when a filler such as graphite powder is added to a polyurethane elastomer, necessary wear characteristics are obtained. For this reason, a large amount of filler is required, and the addition of a large amount of filler will reduce the rubber properties of the material, lower the compression set characteristic, and cause a large sag as a packing. Not only is the effect not obtained, but also the use of a large amount of expensive filler results in an increase in cost and a disadvantage such as a decrease in the machinability of the lip portion.

As the filler, various metal compounds and glass powder can be used. However, in this case as well, disadvantages such as an increase in cost, a reduction in workability, and a loss of the inherent elastic properties inherent to the elastomer are similarly caused. Be looked at.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyurethane elastomer composition which has an improved durability and can be suitably used as a molding material such as packing for a sliding portion.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a polyurethane-based elastomer composition containing a polyurethane-based elastomer and carbon fiber, unfired tetrafluoroethylene resin powder, or both.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Polyol components used for producing a polyurethane elastomer include polyester polyols, polyether polyols, acrylic polyols, silicone polyols having a molecular weight of about 500 to 3,000, preferably about 1500 to 2500. 1,4-polybutadiene polyol, 1,2-polybutadiene polyol, phenolic polyol, flame-retardant polyol, castor oil polyol and the like are used.

Among them, polyester polyols include dicarboxylic acids such as adipic acid, isophthalic acid and terephthalic acid and ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6
-Hexanediol, trimethylolpropane, condensation reaction products with polyols such as neopentyl glycol,
Polycaprolactone polyols, polycarbonate polyols and the like are used, and as the polyether polyols, polypropylene glycol-based polyols or ethylene oxide-modified or amine-modified products thereof, or polyoxytetramethylene glycol are used.

[0010] Other diisocyanates as reaction components include 1,4-tetramethylene diisocyanate, 1,6
-Hexamethylene diisocyanate, aliphatic diisocyanate such as lysine diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, alicyclic diisocyanate or xylylene diisocyanate such as hydrogenated 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, 4, 4'-diphenylmethane diisocyanate, tolidine diisocyanate, p
-An aromatic diisocyanate such as phenylene diisocyanate and 1,5-naphthylene diisocyanate is used.

At the time of the reaction between the two, a chain growth agent can be allowed to coexist in the reaction system. Examples of the chain growth agent include 1,4-butanediol, 1,6-hexanediol,
Glycols such as 3-butanediol, p-phenylenedi (β-hydroxyethyl) ether, p-xylylene glycol, glycerin monoallyl ether, dimethylol hydropyran, ethylenediamine, 3,3′-dichloro-4,4′- Diamines such as diaminodiphenylmethane, diethyltoluylenediamine, N, N'-diaminopiperidine and water are used.

When carbon fibers are used in the present invention, the urethanization reaction using the above components can be carried out in the presence of carbon fibers to form a composite, or after the polyurethane reaction, a Banbury mixer is used. And compounding using an extruder. When unfired tetrafluoroethylene resin powder is used alone or in combination with carbon fiber, it can be added at the prepolymer stage, but after performing the polyurethane conversion reaction, using a Banbury mixer or an extruder. The method of compounding is suitable.

More specifically, the following method is used. (1) After mixing these fillers with the polyol component, excess diisocyanate is added and reacted. A chain growth agent is added to the obtained liquid dipolymer containing advantageous diisocyanate, poured into a mold, cured for a predetermined time, taken out of the mold, or in the same shape or pulverized, and then used in an injection molding machine. After being heated and melted by using, it is heated at a temperature of 80 to 120 ° C. for about 15 to 48 hours in a state of being reshaped in a molding die. (2) high molecular weight dihydroxy compounds, these fillers,
The chain growing agent and diisocyanate (used in lesser equivalents than the functional groups present in both the dihydroxy compound and the chain growing agent) are mixed and reacted. The reaction product can be stored and rolled and can be crosslinked at a later stage by mixing with other diisocyanates. As this diisocyanate 4,
When 4'-diphenylmethane diisocyanate is used, it can be crosslinked by peroxide. Also,
When an unsaturated chain growth agent is used, it can be crosslinked with sulfur, formaldehyde, or the like.

The length of the carbon fiber is about 30 μm to 3 μm.
mm, preferably about 50 μm to 1 mm, having a diameter of about 1 to 50 μm, preferably about 5 to 30 μm, is about 1 to 6 parts by weight, preferably about 2 to 5 parts by weight, per 100 parts by weight of the produced polyurethane elastomer.
Used in parts by weight. If the addition ratio is less than this, the effect of improving the wear resistance as intended by the present invention is not obtained. On the other hand, if the addition ratio is higher than this, not only the cost is increased, but also the workability is increased. And the decrease in flexibility becomes remarkable.

As the unfired tetrafluoroethylene resin powder, a PTFE (polytetrafluoroethylene) powder having a particle size of about 0.5 to 100 μm, preferably about 1 to 60 μm is generally used, and is formed of a polyurethane elastomer. About 0.5 to 10 parts by weight, preferably about 2 to 6 parts per 100 parts by weight
Used in parts by weight. If the addition ratio is lower than this, the effect of improving the wear resistance as intended by the present invention cannot be obtained, while if the addition ratio is higher than this, it is not preferable in terms of cost and flexibility. When used together with carbon fiber, it is desirable that the total of both is limited to about 10 parts by weight or less.

The polyurethane elastomer composition of the present invention containing the above components as essential components may further contain, if necessary, other fillers, metal oxides or hydroxides, lubricants,
An antioxidant or the like is blended and used.

When carbon fibers are added and cured during the production of the polyurethane elastomer, the cured product is pulverized,
After the pulverized material is formed into a sheet or the like using an injection molding machine or the like, secondary crosslinking (oven crosslinking) is performed at about 80 to 120 ° C. for about 15 to 48 hours. Also, after adding carbon fiber or unfired tetrafluoroethylene resin powder to the prepolymer and then reacting with a chain extender to form a polyurethane, the polyurethane conversion reaction was carried out in a mold and molded into a sheet or the like. Thereafter, secondary crosslinking is performed.

[0018]

The polyurethane elastomer composition according to the present invention uses a relatively small amount of carbon fiber or unvulcanized tetrafluoroethylene resin powder of about 10 parts by weight or less per 100 parts by weight of the polyurethane elastomer. It is excellent in cost performance, and has improved abrasion resistance and compatibility with sag resistance without substantially impairing the inherent flexibility and compression set characteristics of the polyurethane elastomer.

More specifically, (1) Since the effect of reducing abrasion can be obtained with a small amount of filling, it is excellent in cutting workability at the time of forming the packing lip as compared with the case where other fillers are blended. It is possible to manufacture a highly accurate shape at a lower cost. (2) Even for polyurethane elastomers of a type that could not be selected due to the problem of wear in the past, the wear characteristics can be improved by adding a filler that does not impair the rubber characteristics, so it is preferably used as a molding material for packing. Can be. (3) By suppressing the wear and sagging of the packing, it becomes possible to maintain the interference for a long period of time while maintaining the initial contact surface pressure distribution, and a long life is achieved.

The polyurethane elastomer composition of the present invention exhibiting such effects can be used as a seal for sliding parts such as a reciprocating packing, a reciprocating buffering, a reciprocating dust seal, a rotating seal, and particularly for a hydraulic cylinder sliding part. It is suitably used as a molding material for a seal.

[0021]

Next, the present invention will be described with reference to examples.

Example 1 700 g of polycaprolactone diol (OH value: 56.1) and carbon fiber (Donacarbo S-2404N, Osaka Gas Chemicals; length: 30)
While heating a mixture of 40 g (about 4 phr with respect to the produced polyurethane) of 40 g (approximately 4 phr to the produced polyurethane), 245 g of trizine diisocyanate (molecular weight: 264) was added thereto, and the mixture was stirred under reduced pressure for about 30 to 40 minutes. Thereafter, 44 g of 1,4-butanediol was added, and the mixture was immediately poured on a hot plate and cured. The cured product is pulverized, and the pulverized product is formed into a sheet (150 × 150 × 2 m
m), and then subjected to secondary crosslinking (oven crosslinking) at a temperature of about 100 to 120 ° C. for 48 hours.

Example 2 In Example 1, 20 g of unfired PTFE powder (PTFE 6J, a product of Mitsui Fluorochemicals; particle size: 470 μm) was used instead of carbon fiber.
(About 2 phr relative to the polyurethane produced).

Comparative Example 1 In Example 1, no carbon fiber was used.

Comparative Example 2 In Example 1, the same amount of molybdenum disulfide powder was used instead of carbon fiber.

Example 3 100 g of polycarbonate diol (OH value: 55.7) and isophorone diisocyanate (molecular weight: 223.3) were placed under reduced pressure at 80 ° C.
Reaction for 30 minutes, and carbon fiber 6g
(About 2 phr for the generated polyurethane) and unfired PTFE (P
6 g (TFE 6J) (about 2 phr based on the polyurethane produced) was added and mixed, and then 103.2 g of trimethylene bis (4-aminobenzoate) heated to about 130 to 135 ° C. and melted was added. After injecting this into a mold and curing, about 80 ~
Secondary crosslinking (oven crosslinking) was performed at 100 ° C. for 15 hours, and vulcanized and formed into a sheet (150 × 150 × 2 mm).

Comparative Example 3 In Example 3, no carbon fiber or unfired PTFE was used.

Comparative Example 4 In Example 3, 30 g of graphite powder (approximately
10 phr) was used.

The vulcanized sheet obtained in each of the above Examples and Comparative Examples was subjected to normal physical properties (according to ASTDD-412-83), compression set (100 ° C., 70 hours), and friction and wear characteristics (comparative material SUS3).
04, the dynamic friction coefficient and the wear depth under the conditions of a linear velocity of 200 mm / sec, a load of 20 kg / cm ² , and a dry friction of 15 minutes were measured. The results obtained are shown in the following table. Table Measurement items Actual-1 Actual- 2Comparative- 1Comparative-2 Actual-3Comparative- 3Comparative- 4 [Normal physical properties] Hardness (point) 88 88 87 88 93 92 95 40 38 39 Elongation (%) 482 505 480 420 560 550 380 [Compression set] 100 ° C, 70 hours (%) 32 32 33 33 37 35 44 [Friction and wear properties] Dynamic friction coefficient 0.436 0.520 0.920 0.640 0.406 0.720 0.530 Wear depth (Mm) 0.37 0.58 1.10 0.67 0.40 0.81 0.58

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiyuki Abe 30 Miyado, Nihonmatsu-shi, Fukushima NOK Co., Ltd. (72) Takashi Chiba 630-1 Isohara-cho, Isohara-cho, Kitaibaraki-shi, Ibaraki F-term (reference) 3J040 EA16 FA06 FA07 FA11 HA01 HA15 HA30 4J002 BD152 CK021 DA016 FA046 GJ02 GM00

Claims (5)

[Claims] 1. A polyurethane elastomer composition comprising a polyurethane elastomer and carbon fibers. 2. A polyurethane elastomer composition comprising a polyurethane elastomer and unfired tetrafluoroethylene resin powder. 3. A polyurethane elastomer composition comprising a polyurethane elastomer, carbon fiber and unfired tetrafluoroethylene resin powder. 4. A packing for a sliding part formed by vulcanization from the polyurethane elastomer composition according to claim 1, 2, or 3. 5. The packing for a sliding portion according to claim 4, which is used for a hydraulic cylinder.