JPH08198927A - Vibration-insulating and cushioning material - Google Patents

Abstract

PURPOSE: To obtain a vibration-insulating and cushioning material having low spring constant and excellent in durability to vibration insulating property and repeated compression. CONSTITUTION: This vibration-insulating and cushioning material comprises low foamed polyurethane elastomer having 0.4-1.0g/cm<3> bulk density and obtained by reacting a polyisocyanate with a polyol and a foaming agent so that isocyanate index becomes 80-120. The polyisocyanate is a modified isocyanate having 5-30wt.% NCO group content and composed of a polyoxytetramethylene glycol or polyoxypropylene glycol having 650-4000 number-average molecular weight and diphenylmethane diisocyanate and the polyol is obtained by mixing a tetrahydrofuran-propylene oxide copolymer triol having 2000-8000 number-average molecular weight with a short chain length diol having <=150 molecular weight and the foaming agent is at least one kind of a 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, in order to reduce or block vibrations when a vehicle is running, a vibration damping material such as natural rubber or styrene-butadiene copolymer rubber is provided between the rail and the sleepers or the roadbed. It is used.

In recent years, due to the problems of vibration and noise associated with the speeding up and overpassing of railways, it has been required to reduce the spring constant of the above-mentioned vibration-proof / buffer material. Shake
When trying to reduce the spring constant with a cushioning material, problems such as insufficient durability against repeated compression and rubber strength, complicated shape, and load (stress)
However, there is a problem in that the rubber composition is laterally distorted when the rubber is added, and the vibration-proof material is displaced. In addition, 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 650-4000 polyoxytetramethylene glycol or number average molecular weight 650-4
000 polyoxypropylene glycol and diphenylmethane diisocyanate having an NCO group content of 5
30% by weight of modified isocyanate, (B) the polyol is a mixture of a tetrahydrofuran-propylene oxide copolymerized triol having a number average molecular weight of 2000 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 (D) the polyisocyanate and the polyol are reacted so that the isocyanate index is 80 to 120. The present invention relates to an anti-vibration / cushioning material, which is made of a low-foaming polyurethane elastomer having a bulk density of 0.4 to 1.0 g / cm ³ .

[0006]

Functions and Examples As described above, the vibration-damping / buffering material of the present invention comprises the polyisocyanate (A) of polyoxytetramethylene glycol having a number average molecular weight of 650 to 4000 or a number average molecular weight of 650 to 4000. It is a modified isocyanate composed of polyoxypropylene glycol and diphenylmethane diisocyanate and having an NCO group content of 5 to 30% by weight. The (B) polyol has a number average molecular weight of 2000 to
8,000 tetrahydrofuran-propylene oxide copolymerized triol and a short chain length diol having a molecular weight of 150 or less are mixed, and the (C) blowing agent is at least one selected from water and low-boiling aliphatic halides. And (D) a low foaming polyurethane elastomer having a bulk density of 0.4 to 1.0 g / cm ³ obtained by reacting a polyisocyanate and a polyol so that the isocyanate index becomes 80 to 120. Is.

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 (A) polyisocyanate used in the present invention is N composed of polyoxytetramethylene glycol or polyoxypropylene glycol having a number average molecular weight of 650 to 4000 and diphenylmethane diisocyanate.
It is a modified isocyanate having a CO group content of 5 to 30% by weight.

If the number average molecular weight of the polyoxytetramethylene glycol or polyoxypropylene glycol is too low, gelation is likely to occur when a modified isocyanate is prepared, so 650 or more,
It is 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 ratio of polyoxytetramethylene glycol or polyoxypropylene glycol to diphenylmethane diisocyanate is adjusted so that the modified isocyanate obtained has an NCO group content of 5 to 30% by weight. When the NCO group content is too low, the viscosity of the obtained modified isocyanate becomes high, the handling property is deteriorated, and the rigidity of the low-foaming polyurethane elastomer becomes insufficient. It is preferably adjusted to 15% by weight or more, and when it is too much, the viscosity rises too quickly in the reaction with the polyol to be described later, resulting in poor workability in mixing, molding, etc. Since physical properties such as mechanical strength of the foamed polyurethane elastomer become unstable, the content is adjusted to 30% by weight or less, preferably 25% by weight or less.

The polyol used in the present invention is a mixed polyol in which a tetrahydrofuran-propylene oxide copolymerized triol having a number average molecular weight of 2000 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, so the vibration-damping and cushioning material obtained has a low spring constant and excellent durability against repeated compression. Becomes

The tetrahydrofuran-propylene oxide copolymer triol may be either a block copolymer or a random copolymer, but it is usually preferable to use a block copolymer. As the copolymerized triol, one having a ratio of tetrahydrofuran to propylene oxide (tetrahydrofuran / propylene oxide, weight ratio) of usually 60/40 to 90/10 is preferably used.

If the number average molecular weight of the tetrahydrofuran-propylene oxide copolymerized triol is too low, the spring constant of the obtained low-foaming polyurethane elastomer will be high, and therefore, 2000 or more, preferably.
If it is 3,000 or more and is too high, the tensile strength and tear strength of the obtained low-foamed polyurethane elastomer will decrease, and in addition, the mold release time will increase during molding, and productivity will decrease. 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 becomes too flexible, the tensile speed is low, and the compression set is large. Less than or equal to 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 tetrahydrofuran-propylene oxide copolymerized triol and the short chain length diol is not particularly limited and may be appropriately adjusted according to the required physical properties. As an example, in order to improve physical properties such as durability against repeated compression, the short chain length diol should be about 10 to 20 parts by weight with respect to 100 parts by weight of tetrahydrofuran-propylene oxide copolymerized triol. Is preferred.

The mixing ratio of the polyisocyanate and the polyol is 100 times 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 Adjust to 120. 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-expandable polyurethane elastomer becomes extremely hard and it is difficult to achieve a low spring constant, so it is adjusted to 120 or less, preferably 105 or less.

The anti-vibration / cushioning material of the present invention, in addition to the characteristics of polyurethane, is imparted with a specific bulk density to the low-expansion polyurethane elastomer by foaming, so that the low spring constant is achieved. , 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.
Is adjusted so that 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, 1.0g / cm ³ or less, preferably 0.75g
/ 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, 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. Additives such as inorganic fine powders such as calcium carbonate and aluminum hydroxide; coloring agents such as carbon black; antifoaming agents such as silicone; UV absorbers; light stabilizers; antioxidants and the like. it can.

After the reaction, the obtained low-foamed polyurethane elastomer is poured into a molding die 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 2
Anti-vibration / cushioning material can be obtained by secondary curing for 4 hours.

The vibration-damping and cushioning material thus obtained has a low spring constant and is excellent in vibration-damping properties and durability against repeated compression, so it is durable 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, since the vibration damping / cushioning material of the present invention is used for the track pad 1 and the interposing elastic member 5, the vibrations 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 Polyoxytetramethylene glycol (number average molecular weight: 2000, OH value: 56, hereinafter, based on 100 parts by weight of pure MDI,
56.2 parts by weight of PTMG-2000) were mixed and reacted to obtain a modified isocyanate having an NCO group content of 19.9% by weight (hereinafter referred to as modified isocyanate-1).

Production Example 2 In the same manner as in Production Example 1, except that PTMG-2000 was changed to polyoxypropylene glycol (number average molecular weight: 2000, OH value: 56, hereinafter referred to as PPG-2000) in Production Example 1. A modified isocyanate having an NCO group content of 19.8% by weight (hereinafter referred to as modified isocyanate-2) was obtained.

Production Example 3 Instead of PTMG-2000 in Production Example 1, polyoxytetramethylene glycol (number average molecular weight: 1000, O
H value: 112, hereinafter referred to as PTMG-1000), and modified isocyanate having an NCO group content of 19.8% by weight (hereinafter, modified isocyanate) in the same manner as in Production Example 1 except that the compounding amount was changed to 47.9 parts by weight. -3).

Production Example 4 In Production Example 2, instead of PPG-2000, polyoxypropylene glycol (number average molecular weight: 1000, OH value:
112, hereafter referred to as PPG-1000) and the compounding amount was changed to 47.9 parts by weight in the same manner as in Production Example 2.
A modified isocyanate having a CO group content of 19.8% by weight (hereinafter referred to as modified isocyanate-4) was obtained.

Production Example 5 A modified isocyanate having an NCO group content of 14.9% by weight (hereinafter referred to as a modified isocyanate-A) was prepared in the same manner as in Production Example 1 except that the compounding amount of PTMG-2000 was changed to 96.9 parts by weight. I got 5).

Comparative Production Example 1 In Production Example 1, instead of PTMG-2000, trioxypropylene glycol (molecular weight: 192, OH value: 584,
Hereinafter, a modified isocyanate having an NCO group content of 23.1% by weight (hereinafter referred to as modified isocyanate-6) was obtained in the same manner as in Production Example 1 except that TPG was used and the compounding amount was changed to 15.4 parts by weight.

Example 1 Tetrahydrofuran-propylene oxide copolymer triol (number average molecular weight: 6000, OH value: 28.9, hereinafter, P
TG-6000TF) (100 parts by weight) and 16 parts by weight of ethylene glycol are mixed to prepare a polyol. 0.8 parts by weight of triethylenediamine and 0.7 parts by weight of water are added to the polyol and mixed until a uniform composition is obtained. It was kept at 60 ° C.

Next, the obtained mixture and modified isocyanate-1 maintained at about 35 ° C. were blended so that the isocyanate index was 105, 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.

(A) 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 Based on JIS K 6301 "7. Method of tear test", a tear strength (kN / m) was measured at a tensile speed of 500 mm / min using a dumbbell-shaped B-type test piece.

(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 has a size of 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 is between 10 and 50 kN. The spring constant (MN / m) was calculated from the amount of deflection.

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-2 were blended so that the isocyanate index was 105.

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 3 A vibration damping / cushioning material was obtained in the same manner as in Example 1 except that the mixture and the modified isocyanate-3 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 4 In Example 1, instead of PTG-6000TF, tetrahydrofuran-propylene oxide copolymerized triol (number average molecular weight: 3000, OH value: 54.9, hereinafter PTG-
Example 3000 except that modified isocyanate-4 was used in place of modified isocyanate-1.
In the same manner as above, a vibration-proof and cushioning material was obtained.

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 5 A vibration-proof / buffer material was obtained in the same manner as in Example 1 except that modified isocyanate-5 was used instead of modified isocyanate-1.

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

Example 6 A vibration damping / cushioning material was obtained in the same manner as in Example 1 except that the blending amount of ethylene glycol was changed to 12 parts by weight.

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 1 Polyoxypropylene triol (number average molecular weight: 480
0, OH value: 35, hereinafter referred to as PPT-4800) 100 parts by weight and 8 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 added thereto to obtain a uniform mixture. The mixture was mixed and maintained at about 60 ° C. until it had a proper composition.

Next, the obtained mixture and modified isocyanate-6 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 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.

Comparative Example 2 In Example 1, instead of PTG-6000TF, tetrahydrofuran-propylene oxide copolymerized triol (number average molecular weight: 600, OH value: 273, hereinafter PTG-60) was used.
0TF), without ethylene glycol,
A vibration damping / cushioning material was obtained in the same manner as in 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 vibration damping / cushioning material were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 A vibration-proof / buffer material was obtained in the same manner as in Example 1 except that modified isocyanate-6 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.

In addition, in Table 1, the types and blending amounts of the respective components and the isocyanate index for obtaining the vibration proof / buffer material are also shown.

[0067]

[Table 1]

From the results shown in Table 1, the vibration damping / cushioning materials obtained in Examples 1 to 6 are excellent in mechanical strength such as tensile strength and tear strength, have a large elongation, and have a spring strength. Since the constant is about 20 MN / m, the compression set is less than 15%, and the compression fatigue is less than 10%, the spring constant is reduced, and the vibration resistance and durability against repeated compression are excellent. I understand.

[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.

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 650.
Up to 4000 polyoxytetramethylene glycol or polyoxypropylene glycol with a number average molecular weight of 650 to 4000 and diphenylmethane diisocyanate N
A modified isocyanate having a CO group content of 5 to 30% by weight, wherein (B) the polyol has a number average molecular weight of 2000 to 80.
A mixture of a tetrahydrofuran-propylene oxide copolymerized triol of 00 and a short chain length diol having a molecular weight of 150 or less, wherein (C) the foaming agent is at least one selected from water and low-boiling aliphatic halides. And (D) 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 that the isocyanate index is 80 to 120. Anti-vibration and cushioning material.