JPH0827241A - Vibration-proofing and cushioning material - Google Patents

Abstract

PURPOSE:To obtain a vibration-proofing and cushioning material lowered in spring coefficient and excellent in durability to repeated compression. CONSTITUTION:This vibration-proofing and cushioning material is composed of a low-expanded polyurethane elastomer having 0.4-1.0g/cm<3> bulk density obtained by reacting a polyisocyanate which is a modified isocyanate composed of a polyoxypropyleneglycol having 400-4000 number-average molecular weight and diphenylmethane diisocyanate and having 5-30wt.% of NCO group content with a polyol obtained by mixing a polyoxypropylenetriol having 4000-8000 number-average molecular weight with a short-chain length diol having <=150 molecular weight so that isocyanate index becomes 80-120, using a foaming agent comprising at least one kind of compound selected from water and a low boiling point aliphatic halide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping / cushioning material. More specifically, it is a vibration proof that is required to have durability against repeated compression, and can be suitably used as, for example, a vehicle vibration proof material, a railroad pad such as a track pad, a sleeper pad, a slab mat, and a vibration proof material. -Regarding cushioning material.

[0002]

2. Description of the Related Art Conventionally, rubber such as natural rubber or styrene-butadiene copolymer rubber has been used as a vibration-damping / cushioning material for reducing or isolating vibrations during vehicle running.

Generally, in vehicles and the like, the spring constant is reduced in order to reduce the vibration, but if an attempt is made to reduce the spring constant with a vibration-proof / buffer material made of the above-mentioned rubber. In the meantime, the durability against repeated compression and the rubber strength are not sufficient, the shape becomes complicated, and when the load (stress) is applied, it is distorted in the lateral direction and the anti-vibration material is displaced. There is a problem, and further, since rubber is used, the vulcanization time becomes long, which causes a problem in productivity.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has a low spring constant and is excellent in vibration damping and durability against repeated compression. The purpose is to provide the material.

[0005]

That is, the present invention provides a vibration-proof / buffer material obtained by reacting a polyisocyanate, a polyol and a foaming agent, wherein (A) the polyisocyanate has a number average molecular weight of A modified isocyanate having an NCO group content of 5 to 30% by weight consisting of 400 to 4000 polyoxypropylene glycol and diphenylmethane diisocyanate, wherein (B) the polyol is polyoxypropylene triol having a number average molecular weight of 4000 to 8000. A mixture of a short chain diol having a molecular weight of 150 or less, (C) the foaming agent is at least one selected from water and low-boiling aliphatic halides, and (D)
Anti-vibration / buffer, which is made of a low-foaming polyurethane elastomer having a bulk density of 0.4 to 1.0 g / cm ³ obtained by reacting the polyisocyanate and the polyol so as to have an isocyanate index of 80 to 120. Regarding materials

[0006]

FUNCTION AND EXAMPLE As described above, the vibration-damping / buffering material of the present invention contains (A) polyisocyanate having an NCO group content of polyoxypropylene glycol having a number average molecular weight of 400 to 4000 and diphenylmethane diisocyanate. Is a modified isocyanate of 5 to 30% by weight, and (B)
The polyol is a mixture of polyoxypropylene triol having a number average molecular weight of 4000 to 8000 and a short chain length diol having a molecular weight of 150 or less, and (C) the blowing agent is selected from water and low boiling aliphatic halides. At least 1
A low foaming polyurethane elastomer having a bulk density of 0.4 to 1.0 g / cm ³ obtained by reacting a polyisocyanate (D) with a polyol so as to have an isocyanate index of 80 to 120. It was done.

Thus, the specific polyisocyanate,
Using a polyol and a foaming agent, the isocyanate index is allowed to react to a specific value, and the bulk density of the low-expansion polyurethane elastomer is also adjusted to a specific value, which results in a low spring constant and repeated compression. Anti-vibration / cushioning material with excellent durability against

The polyisocyanate (A) used in the present invention is a modified isocyanate composed of polyoxypropylene glycol having a number average molecular weight of 400 to 4000 and diphenylmethane diisocyanate and having an NCO group content of 5 to 30% by weight.

If the number average molecular weight of the polyoxypropylene glycol is too low, it tends to cause gelation when the modified isocyanate is prepared.
It is 400 or more, preferably 1000 or more, and when it is too high, it takes a long time to release from the mold at the time of molding, so it is 4000 or less, preferably 3000 or less.

Examples of the diphenylmethane diisocyanate include 4,4'-diphenylmethane diisocyanate (hereinafter referred to as pure MDI) and polymeric 4,4'-diphenylmethane diisocyanate (hereinafter referred to as polymeric MDI). Pure MD among these
I is particularly preferable because the obtained low-expansion polyurethane elastomer has excellent flex resistance.

The proportion of the polyoxypropylene glycol and diphenylmethane diisocyanate is adjusted so that the modified isocyanate obtained has an NCO group content of 5 to 30% by weight. If the NCO group content is too low, the viscosity of the obtained modified isocyanate becomes high, the handling property is lowered, and the rigidity of the low-foaming polyurethane elastomer becomes insufficient.
It is adjusted to be 5% by weight or more, preferably 15% by weight or more, and if it is too much, the viscosity rises too quickly in the reaction with the polyol described below, and the workability such as mixing and molding is deteriorated. Also, the physical properties such as mechanical strength of the low-expansion polyurethane elastomer obtained will become unstable, so 30% by weight or less, preferably 25% by weight
Adjust as follows.

The polyol used in the present invention is a mixed polyol in which a polyoxypropylene triol having a number average molecular weight of 4000 to 8000 and a short chain length diol having a molecular weight of 150 or less are mixed. By using such a mixed polyol, the low-foaming polyurethane elastomer has a network structure and is difficult to crystallize.
The cushioning material has a low spring constant and is excellent in durability against repeated compression.

If the number average molecular weight of the polyoxypropylene triol is too low, the spring constant of the low-expansion polyurethane elastomer obtained will be high, so that it is 4000 or more, preferably 4500 or more, and too high. In such a case, the tensile strength and tear strength of the obtained low-foamed polyurethane elastomer will decrease, and further, the mold release time will increase during molding and the productivity will decrease, so it is 8000 or less, preferably 6000 or less. .

If the molecular weight of the short chain length diol is too high, the resulting low-expandable polyurethane elastomer will be too soft, the tensile speed will be low, and the compression set will be large. Not more than 134.

Specific examples of the short chain length diol include ethylene glycol, diethylene glycol,
1,4-butanediol, propylene glycol, dipropylene glycol, triethylene glycol and the like can be mentioned, and these can be used alone or in admixture of two or more.

The mixing ratio of the polyoxypropylene triol and the short chain length diol is not particularly limited and may be appropriately adjusted according to the required physical properties. For example, in order to improve physical properties such as durability against repeated compression, it is preferable that the short chain length diol is about 10 to 20 parts by weight with respect to 100 parts by weight of polyoxypropylene triol.

The mixing ratio of the polyisocyanate and the polyol is such that the equivalent ratio of the isocyanate group in the polyisocyanate to the active hydrogen in the polyol (isocyanate group / active hydrogen), that is, the isocyanate index is usually 80 to 120. To adjust. If the isocyanate index is too small, water absorption is likely to occur, and the mechanical strength of the low-expansion polyurethane elastomer obtained will decrease, so 80 or more, preferably adjusted to 100 or more,
On the other hand, if it is too large, the low-foam polyurethane elastomer becomes extremely hard and it is difficult to achieve a low spring constant. Therefore, it is adjusted to 120 or less, preferably 105 or less.

The anti-vibration / cushioning material of the present invention has a low spring constant because the low foaming polyurethane elastomer has a specific bulk density due to foaming in addition to the characteristics of polyurethane. , In the present invention,
As the foaming agent, at least one selected from water and low boiling point aliphatic halides is used.

As the low boiling point aliphatic halide,
Examples include hydrochlorofluorocarbons such as difluorochloromethane, hydrofluorocarbons such as tetrafluoromethane, and alkylene chlorides such as methylene chloride and ethylene chloride.

The amount of the foaming agent used is such that the obtained low-foaming polyurethane elastomer has a bulk density of 0.4 to 1.0 g / cm.
³ and is adjusted to be. If the bulk density of the low-expansion polyurethane elastomer is too small, the mechanical strength and rigidity will be insufficient, so 0.4 g
/ Cm ³ or more, preferably 0.55 g / cm ³ or more, and when it is too large, it has a high hardness that cannot be said to be a foam, and it is difficult to reduce the spring constant. Therefore, 1.0 g / cm ³ or less, preferably 0.
Adjust so that it is 75 g / cm ³ or less.

In the present invention, a catalyst may be appropriately added when the polyisocyanate, the polyol and the foaming agent are reacted.

Typical examples of the catalyst include amine catalysts such as triethylenediamine, triethylamine, N-methylmorpholine, tetramethylbutanediamine and N, N-dimethylethanolamine, and tin such as stannas octoate. Examples include system catalysts, and these catalysts may be used alone or in combination of two or more.

The low-foaming polyurethane elastomer used in the present invention is obtained by reacting a polyisocyanate, a polyol and a blowing agent. As an example thereof, for example, water and, if necessary, a catalyst may be mixed with a polyol and mixed until a uniform composition is obtained, and then polyisocyanate may be mixed therewith, followed by heating to about 20 to 70 ° C. In addition, when mixing these components,
For example, using a propeller stirrer etc.
You may mix at about 00 rpm.

The low-foamed polyurethane elastomer thus obtained has a bulk density of 0.4 to 1.0 g / cm ³ , and the low-foamed polyurethane elastomer may contain metal powder such as iron powder, if necessary. Calcium carbonate,
Filler such as inorganic fine powder such as aluminum hydroxide;
Colorants such as carbon black; antifoaming agents such as silicone; ultraviolet absorbers; light stabilizers; antioxidants and other additives may be added.

After the reaction, the obtained low-foamed polyurethane elastomer is poured into a mold having a predetermined shape heated to, for example, about 50 to 120 ° C., and an appropriate amount thereof is injected, and the temperature is about 50 to 120 ° C. for 5 to 30 minutes. After the primary curing, the obtained molded product is released from the mold, and if necessary, at a temperature of 90 to 120 ° C for 8 to
Anti-vibration / cushioning material can be obtained by secondary curing for 24 hours.

The anti-vibration / cushioning material thus obtained has a low spring constant and is excellent in anti-vibration properties and durability against repeated compression. It can be suitably used as a vibration damping material for vehicles, a rail cushioning material such as a track pad, a sleeper pad, and a slab mat, a vibration damping material, etc.

Next, FIG. 1 is a schematic explanatory view of an embodiment of a rail fastening device using the vibration damping / cushioning material of the present invention as a track pad and an interposing elastic material. In the rail fastening device shown in FIG. 1, between the rail 2 and the adjustment packing 4 made of, for example, metal, the vibration-proof and
A track pad 1 made of a cushioning material is provided, and an interposing elastic material 5 made of a vibration-proof and cushioning material of the present invention is provided between the upper tie plate 6 and the base plate 7. These upper tie plate 6, interposing elastic member 5, and base plate 7 are anchor T bolts 9 embedded in the support 8.
Fixed by this, rail 2 on tie plate 6 on this
Are fixed by the leaf spring 3.

As described above, in such a rail fastening device, the vibration damping / cushioning material of the present invention is used for the track pad 1 and the interposing elastic member 5, so that the vibration when the railway vehicle passes through these tracks. It is sufficiently absorbed by the pad 1 and the interposing elastic member 5, and excellent vibration damping property and cushioning property are exhibited.

Next, the anti-vibration / cushioning material of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Production Example 1 56.2 parts by weight of polyoxypropylene glycol (number average molecular weight: 2000, OH value: 56) was mixed with 100 parts by weight of pure MDI, and these were reacted to have an NCO group content of 20% by weight. Modified isocyanate (hereinafter, modified isocyanate-
I got 1).

Production Example 2 A modified isocyanate having an NCO group content of 15% by weight (hereinafter referred to as a modified isocyanate) was produced in the same manner as in Production Example 1 except that the compounding amount of polyoxypropylene glycol was changed to 96.9 parts by weight. -2).

Production Example 3 In Production Example 1, polyoxypropylene glycol having a number average molecular weight of 1000 and an OH value of 112 was used.
A modified isocyanate having an NCO group content of 19.8% by weight (hereinafter referred to as modified isocyanate-3) was obtained in the same manner as in Production Example 1 except that the compounding amount was changed to 47.9 parts by weight.

Production Example 4 In the same manner as in Production Example 1, except that polyoxypropylene glycol having a number average molecular weight of 3000 and an OH number of 37 was used and the compounding amount was changed to 83.8 parts by weight. A modified isocyanate having an NCO group content of 17% by weight (hereinafter referred to as modified isocyanate-4) was obtained.

Comparative Production Example 1 Polytetramethylene glycol (number average molecular weight: 3000, OH value: 37) was used in place of polyoxypropylene glycol, and the compounding amount was changed to 83.8 parts by weight. In the same manner as in Production Example 1, a modified isocyanate having an NCO group content of 20% by weight (hereinafter referred to as modified isocyanate-5) was obtained.

Comparative Production Example 2 In Production Example 1, the same polytetramethylene glycol as that used in Comparative Production Example 1 was used in place of polyoxypropylene glycol, and the compounding amount was changed to 29.5 parts by weight. As in 1, the NCO group content is 25
A weight% modified isocyanate (hereinafter referred to as modified isocyanate-6) was obtained.

Example 1 Polyoxypropylene triol (number average molecular weight: 600)
0, OH value: 27.6) 100 parts by weight and 16 parts by weight of ethylene glycol are mixed to prepare a polyol, and 0.8 parts by weight of triethylenediamine and 0.7 parts by weight of water are mixed therein,
The mixture was mixed and kept at about 60 ° C. until a uniform composition was obtained.

Next, the obtained mixture and modified isocyanate-1 maintained at about 35 ° C. were blended so that the isocyanate index was 101, and the rotation speed was about 3000 rpm for about 60 seconds using a propeller stirrer. The mixture was stirred and mixed, and then poured into a mold preheated to about 60 ° C.

About 3 minutes after casting, the contents were taken out and post-cured in a hot air oven at 110 ° C. for 24 hours to obtain a vibration-proof / buffer material (140 × 180 × 10 mm).

Various physical properties of the obtained antivibration / cushioning material were examined according to the following methods. Table 1 shows the results.

(B) Bulk Density The bulk density (g / cm ³ ) was measured according to JIS Z 8807 "Measurement method from volume".

(B) Tensile strength According to JIS K 6301 "3. Method of tensile test", a dumbbell-shaped No. 3 test piece was used to measure the tensile strength (MPa) at a tensile speed of 500 mm / min.

(C) Elongation Elongation (%) was measured in the same manner as in (b) Tensile strength.

(D) Tear strength Tear strength (kN / m) was measured at a tensile speed of 500 mm / min using a dumbbell-shaped B-type test piece in accordance with JIS K 6301 "7. Method of tear test". .

(E) Heat resistance According to JIS K 6301 “6. Aging test”, “6.3 Air heating aging test”, dumbbell-shaped No. 3 test piece was heated to 70 ° C.
After heat aging for 96 hours at room temperature, let it cool at room temperature for 1 hour, and immediately perform a tensile test in the same manner as (b) Tensile strength, and use the value of (b) tensile strength before heat aging as a reference. The retention rate (%) was calculated as

(F) Compression set In accordance with ASTM D395 Method (A), a constant load compression tester was used to measure a test piece of 25 × 25 × 10 mm at 1.5 kN.
Load, and treat at 70 ℃ for 48 hours, then at room temperature
After cooling for 24 hours, the thickness of the test piece was measured, and the change rate (%) was obtained based on the thickness before the test.

(G) Compressive Fatigue Using a fatigue tester, a test piece of 50 × 50 × 10 mm was 9
Apply a load of kN and generate a sine wave of ± 6 kN at a frequency of 5 Hz.
After 1 million fatigue treatments, the thickness of the test piece was measured by allowing it to cool at room temperature for about 24 hours, and the rate of change (%) was calculated based on the thickness before the test.

(H) Spring constant Using a compression tester, after precompressing twice on a test piece of 140 × 180 × 10 mm, a load is applied up to 300 kN, and the obtained load-deflection curve of 10 to 50 kN is obtained. The spring constant (MN / m) was calculated from the amount of deflection between them.

Example 2 A vibration damping / cushioning material was obtained in the same manner as in Example 1 except that the mixture and the modified isocyanate-1 were blended so that the isocyanate index was 105.

Various physical properties of the obtained vibration damping / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Example 3 A vibration damping / cushioning material was obtained in the same manner as in Example 2 except that the amount of ethylene glycol used was changed from 16 parts by weight to 12 parts by weight.

Various physical properties of the obtained antivibration / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Example 4 A vibration-proof / buffer material was obtained in the same manner as in Example 1 except that modified isocyanate-2 was used instead of modified isocyanate-1.

Various physical properties of the obtained antivibration / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Example 5 An antivibration / buffer material was obtained in the same manner as in Example 2 except that modified isocyanate-3 was used instead of modified isocyanate-1.

Various physical properties of the obtained vibration damping / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Example 6 In Example 2, polyoxypropylene triol having a number average molecular weight of 4800 and an OH value of 35 was used, and modified isocyanate-1 was used instead of modified isocyanate-1.
A vibration proof / buffer material was obtained in the same manner as in Example 2 except that No. 4 was used.

Various physical properties of the obtained vibration damping / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Example 7 A vibration-proof / buffer material was obtained in the same manner as in Example 6 except that modified isocyanate-1 was used instead of modified isocyanate-4.

Various physical properties of the obtained antivibration / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Polyoxypropylene triol (number average molecular weight: 300
0, OH number: 56) 100 parts by weight and ethylene glycol 27.6
1 part by weight of triethylenediamine and 5.2 parts by weight of water are added to the polyol to prepare a polyol.
The mixture was mixed and kept at about 60 ° C. until a uniform composition was obtained.

Next, the obtained mixture and modified isocyanate-5 kept at about 35 ° C. were blended so that the isocyanate index was 105, and a vibration-proof / buffer material was obtained in the same manner as in Example 2. .

Various physical properties of the obtained vibration damping / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 In Comparative Example 1, polyoxypropylene triol having a number average molecular weight of 600 and an OH value of 273 was used.
A vibration damping / cushioning material was obtained in the same manner as in Comparative Example 1 except that the amount of water was changed to 1.5 parts by weight and the amount of triethylenediamine was changed to 0.7 parts by weight.

Various physical properties of the obtained antivibration / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 In Comparative Example 1, the blending amount of ethylene glycol was 67.5.
The amount of water was changed to 5 parts by weight, the amount of triethylenediamine was changed to 2.5 parts by weight, and modified isocyanate-6 was used instead of modified isocyanate-5. I got anti-vibration and cushioning material.

Various physical properties of the obtained antivibration / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

[0067]

[Table 1]

From the results shown in Table 1, the vibration-damping / cushioning materials obtained in Examples 1 to 7 are excellent in mechanical strength such as tensile strength and tear strength, and have a large elongation. The spring constant is about 20 MN / m or less, the compression set is less than 10%, and the compression fatigue is less than 10%.
It can be seen that the spring constant is reduced and the durability against repeated compression is excellent.

[0069]

The anti-vibration / cushioning material of the present invention has a low spring constant and is excellent in anti-vibration property and durability against repeated compression. It can be suitably used as a railroad cushioning material such as a sleeper pad and a slab mat, and a vibration isolator.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of a rail fastening device in which a vibration damping / cushioning material of the present invention is used for a track pad and an interposing elastic material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichiro Hara Inventor, Koichiro Hara 3-2-15, Meiwadori, Hyogo-ku, Kobe, Hyogo Bando Kagaku Co., Ltd. 38 Inside the Railway Technical Research Institute (72) Naoto Mifune 2-8 Mitsumachi, Kokubunji City, Tokyo 38 Inside the National Railway Research Institute (72) Hiroshi Kumazaki 2-8 Mitsumachi, Kokubunji, Tokyo 38 Inside the Railway Technical Research Institute

Claims (1)

[Claims] 1. An anti-vibration / buffer material obtained by reacting a polyisocyanate, a polyol and a foaming agent,
(A) The polyisocyanate has a number average molecular weight of 400
The content of NCO group consisting of ~ 4000 polyoxypropylene glycol and diphenylmethane diisocyanate is 5
~ 30 wt% modified isocyanate, (B) the polyol is a mixture of polyoxypropylene triol having a number average molecular weight of 4000 to 8000 and a short chain length diol having a molecular weight of 150 or less, (C) The foaming agent is at least one selected from water and low-boiling aliphatic halides, and is obtained by reacting (D) the polyisocyanate and the polyol so that the isocyanate index becomes 80 to 120. Bulk density is 0.4 to 1.0 g / c
Anti-vibration / cushioning material characterized by being made of m ³ low-foaming polyurethane elastomer.