JPH11302355A - Foamable polyurethane elastomer composition and vibration-proof material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foamable polyurethane elastomer composition using inexpensive MDI and giving an elastomer scarcely generating permanent compression set and having sufficient load resistance, sufficient flexibility and excellent moldability, and a vibration-proof material. SOLUTION: This foamable polyurethane elastomer composition comprises (A) an isocyanate-terminated prepolymer comprising (A-1) an isocyanate compound and (A-2) a polyol component and (B) a foaming component comprising water, a foam stabilizer and a catalyst. Therein, the component A-1 in the component A is 4, 4'-diphenylmethanediisocyanate, and the component A-2 is a polyol containing a polyetheresterpolyol having an average functional group number of 2.1-2.5 and produced from (A-2-1) a triol compound, (A-2-2) a polyoxyalkylene glycol and (A-2-3) an aliphatic dibasic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a foamed polyurethane elastomer composition having a small compression set, sufficient load bearing capacity, excellent storage stability of a prepolymer, and excellent molding workability during elastomer production. It is related to vibration insulators.

[0002]

2. Description of the Related Art Foamed polyurethane elastomers are widely used as auxiliary rubbers and cushioning materials for vibration dampers for automobile suspensions due to their excellent bending fatigue characteristics and mechanical strength. Conventionally, foamed polyurethane elastomers having excellent performance include 1,5-naphthalenediisocyanate (hereinafter abbreviated as NDI) and 3,3′-dimethyl-4,
It is manufactured by mixing a foaming agent comprising an isocyanate group-terminated prepolymer obtained by reacting 4′-biphenylenediisocyanate (hereinafter abbreviated as TODI) with a polyester polyol, water, a catalyst and a silicone-based foam stabilizer, followed by foaming and curing. ing.

[0003] However, those using the above-mentioned NDI or TODI have excellent performance such as small settling when repeatedly subjected to compression set and high load, and have sufficient durability, but have a prepolymer pot. There is a drawback that the prepolymer has to be prepared each time because the life is short, the viscosity increases with time, and the storage stability is poor. In addition, the disadvantage that NDI and TODI are extremely expensive is always mentioned as a problem in practical use. However, when the isocyanate is replaced with inexpensive 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), a product having excellent storage stability and good workability can be obtained, but the conventional NDI or TODI is used. It is inferior in dynamic characteristics and compression set when a very large load of 50 to 80% is applied from the initial state, and has a disadvantage that it is swollen or cracked when it is released from the mold. Therefore, studies have been made to obtain a foamed polyurethane elastomer which can solve the drawbacks caused when MDI is used, but it has not been put to practical use.

[0004] For example, JP-A-7-224139 discloses that the mechanical properties obtained by reacting an isocyanate group-terminated prepolymer with a blowing agent composed of water, a low molecular weight diol and a polyether polyol having a number average molecular weight of 5,000 to 10,000 are disclosed. There have been proposals for fine foamed polyurethane elastomers having excellent compression set and small compression set. However, in this case, the compatibility between water in the foaming agent and the polyether polyol is not always good, and physical property deterioration due to uneven reaction and foaming is expected.

[0005] JP-A-7-252340 discloses an MD
There has been proposed a foamed polyurethane elastomer obtained by foaming and curing an isocyanate-terminated prepolymer, a hydroxyl-terminated prepolymer, and a foaming component using I. However, TODI is used as a diisocyanate component for the hydroxyl-terminated prepolymer. Thus, an inexpensive microcellular foamed polyurethane elastomer cannot be obtained.
Further, in this case, since the hydroxyl group-terminated prepolymer is contained in the foaming agent, the crosslinking and curing reaction is slow, and a long time is required for demolding, which may reduce the workability.

Japanese Unexamined Patent Publication (Kokai) No. 60-235824 discloses that the mixing ratio (EG / BG) of ethylene glycol (EG) and butylene glycol is 70/30 to 30/7.
There is a proposal for a urethane elastomer sponge characterized by containing 2,2-bis (4′-oxyphenyl) propane in adipate adjusted to be 0, but the adipate is composed of 2,2-bis ( Depending on the content of 4'-oxyphenyl) propane, it was impossible to obtain a product having excellent molding workability such that the viscosity of the obtained prepolymer was increased and cracks were generated during foaming and curing.

Further, Japanese Patent Application Laid-Open No. 61-250019 discloses that a copolymer of polytetramethylene glycol and ε-caprolactone, an NCO-terminated prepolymer obtained from MDI, and a blowing agent containing water as a main component can be used under a high load. There is an example of producing a microcellular polyurethane elastomer which is a vibration-proof material that can sufficiently withstand repeated compression and has excellent cold resistance and moisture-heat hydrolysis resistance. However, even in this case, the polyol component has an average number of functional groups of 2.0, and is sufficiently satisfactory in some aspects such as mechanical strength and moldability as compared with those using NDI or TODI when used as a vibration damping material. No performance is obtained.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an inexpensive MD.
The object of the present invention is to provide a foamed polyurethane elastomer composition and a vibration damping material which are excellent in moldability during elastomer production while having a small compression set and sufficient load resistance and bending resistance when I is used. And

[0009]

Means for Solving the Problems The present inventors have made intensive studies to achieve these objects, and as a result, they can be widely used as vibration damping materials including auxiliary rubbers for vibration damping materials for automobile suspensions. The present inventors have found a foamed polyurethane elastomer composition and completed the present invention.

That is, the present invention relates to (A-1) an isocyanate
(A-2) A foamed polyurethane elastomer composition comprising an isocyanate-terminated prepolymer (A) comprising a polyol component and a foaming component (B) comprising water, a foam stabilizer and a catalyst, wherein (A-1) is , 4,4′-diphenylmethane diisocyanate, (A-2) is (A-2-1) a triol compound, (A-2-2) polyoxyalkylene glycol, (A-
2-3) isocyanate group-terminated urethane prepolymer consisting of a polyol containing a polyetherester polyol having an average functional group number of 2.1 to 2.5 and an aliphatic dibasic acid
(A) is a foamed polyurethane elastomer composition, preferably the average molecular weight of the polyetherester polyol in the polyol (A-2) is from 1500 to 4
000, (A-1) / (A-2) of the prepolymer (A) =
Another object of the present invention is to provide a vibration damping material characterized in that the NCO / OH (equivalent ratio) is 1.6 / 1 to 5.0 / 1 and that the foamed polyurethane elastomer composition is used.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The component (A-1) of the present invention comprises 4,4 ′
-Diphenylmethane diisocyanate is mainly used, but other diisocyanates may be used in combination within a range that does not impair the effects of the present invention, and examples thereof include aromatic, alicyclic, and aliphatic. For example, 1,
5-naphthalene diisocyanate, 3,3′-dimethyl-4,4′-biphenyl diisocyanate, polymethylene polyphenyl isocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
A mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, p
-Phenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, and the like,
It is not limited to these.

The polyetherester polyol of the component (A-2) of the present invention comprises (A-2-1) a triol compound, (A-2-2) a polyoxyalkylene glycol and (A-2-3) an aliphatic compound. And dibasic acids.

As the triol compound (A-2-1), for example, trimethylolpropane, trimethyloloctane,
Glycerin and the like. These can be used alone or in combination of two or more. Particularly preferred is trimethylolpropane.

Polyoxyalkylene glycol (A-2-2)
The number average molecular weight is preferably from 500 to 3,000, and more preferably from 500 to 2,000. For example, polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran by a method usually used is exemplified. However, the polyoxyalkylene glycol is not particularly limited as long as the target polyetherester polyol of the component (A-2) has a target average number of functional groups and molecular weight.

The mixing ratio of the above-mentioned triol compound (A-2-1) and polyoxyalkylene glycol (A-2-2) is such that a predetermined amount is mixed and used according to the desired average number of functional groups. .

In addition to the above-mentioned triol compound (A-2-1) and polyoxyalkylene glycol (A-2-2), if necessary, a short-chain diol usually used as a polyhydroxy compound may be used. .

The short-chain diols include aliphatic short-chain diols having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 2-methyl-1,3-propanediol,
1,4-butanediol, neopentyl glycol,
1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-
Trimethyl 1,3-pentanediol, 2-ethyl 1,
3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like, and these may be used alone or in combination of two or more. Can be.

Examples of the aliphatic dibasic acid (A-2-3) include succinic acid, glutaric acid, adipic acid, pimelic acid, shuberic acid, azelaic acid, sebacic acid, 1,1
Examples thereof include 0-decanedicarboxylic acid and 1,12-dodecanedicarboxylic acid, and these may be used alone or in combination of two or more.

These polyetherester polyols have an average number of functional groups in the range of 2.1 to 2.5.

In order to obtain a polyetherester polyol having the desired average number of functional groups, the mixing ratio of the triol compound (A-2-1) and the polyoxyalkylene glycol (A-2-2) is adjusted as described above. In addition to synthesizing by mixing a predetermined amount in accordance with the desired average number of functional groups, of course, a polyol having an average number of 2.0 and a polyol having an average number of more than 2.0 are prepared in advance, mixed and used. However, the average number of functional groups in the mixture is 2.1.
It needs to be prepared in the range of ~ 2.5.

The polyetherester polyol is
For example, when the average number of functional groups obtained from a polyoxyalkylene glycol and an aliphatic dibasic acid is smaller than 2.1, the resulting foamed polyurethane elastomer has a large permanent compression set, and is not practical. If the average number of functional groups exceeds 2.5, a gel is generated at the stage of synthesizing the prepolymer having terminal isocyanate groups, or the viscosity of the prepolymer becomes extremely high, and the mixing state with the foaming agent is poor. Occur.

The polyetherester polyol (A-2) shown above accounts for 20 to 100% by weight of the polyol component.
It is preferred that If the amount is less than 20% by weight, the excellent feature that the compression set is small is not exhibited, and the durability is inferior.

As the polyol which can be used in combination with the polyetherester polyol polyol as the component (A-2), there can be used a general polyesterether polyol comprising an acid component of a dibasic acid such as adipic acid and a short-chain polyol component. And polyesterethers obtained by ring-opening polymerization of lactones using short-chain glycols as a reaction initiator, and polyether polyols such as polytetramethylene glycol and polypropylene glycol. Of course, these combined polyols may have an average number of functional groups exceeding 2.0, and may be used to such an extent that the effect is not impaired.

As a means for obtaining the prepolymer (A) having a terminal isocyanate group from the polyetherester polyol (A-2) and the MDI (A-1), a conventionally known production method can be used. The equivalent ratio of MDI to be used and the polyetherester polyol = (A-1) / (A-2) is preferably NC
O / OH = 1.6 to 5.0. When the ratio of NCO / OH is less than 1.6, the viscosity of the isocyanate group-terminated prepolymer increases, the workability decreases, and the NCO / OH ratio decreases.
When the ratio of OH exceeds 5.0, the elasticity of the obtained foamed polyurethane elastomer is impaired, and the foamed polyurethane elastomer is not practical.

In the present invention, if necessary, a stabilizer such as a reactivity modifier or an antioxidant may be added during prepolymerization.

The ratio of the isocyanate group equivalent of the isocyanate group-terminated prepolymer (A) of the present invention to the hydroxyl equivalent in the foaming agent component (B) is preferably 1.0 / 0.9 to 1.0 / 1.0.
It is necessary to prepare in the range of 1.1. Outside the above range, the physical properties and durability of the obtained foamed polyurethane elastomer are reduced. The amount of water contained in the foaming agent is not particularly limited, but the ratio of the isocyanate group-terminated prepolymer to the foaming agent is preferably 100:
It is prepared and used in the range of 1 to 50.

The water used in the foaming agent component (B) of the present invention is preferably pure water or ion-exchanged water. As the catalyst, known organic metal compounds and amines can be used as long as they promote foaming and curing, and amines are preferable. These include, for example, tertiary amines such as triethylamine and triethylenediamine, nitrogen compounds such as morpholine and N-methylmorpholine, metal salts such as potassium acetate and zinc stearate, and organic metal compounds such as dibutyltin dilaurate and dibutyltin oxide. And the like. Further, the foam stabilizer is preferably a silicone surfactant, and a known surfactant such as SH-193 (Toray Dow Corning Silicone Co., Ltd.) can be used.

If necessary, an organic chain extender can be added simultaneously with the polyol component or stepwise during preparation of the prepolymer or during foaming of the elastomer in order to obtain the desired physical properties. Examples of the organic chain extender include short-chain diols.

As the foaming agent component (B), an aqueous solution containing a commercially available fatty acid such as ricinoleic acid modified with sodium sulfate can also be used. Examples of such a foaming agent include Agiti SV (manufactured by Sumitomo Bayer Urethane Co., Ltd.).

The foaming agent component (B) of the present invention may contain, if necessary, an auxiliary agent in addition to water, a foam stabilizer and a catalyst. Examples of such an auxiliary include an antioxidant, an ultraviolet absorber, and a flame retardant. Known auxiliaries can be used.

The operation of mixing and agitating the above foaming agent component (B) and the above-mentioned isocyanate-terminated prepolymer (A) and injecting and foaming it into a mold can be sufficiently performed by a known technique. As a method for producing a molded article using the polyurethane elastomer composition of the present invention, a component (A) and a component (B) are heated and mixed at 50 to 100 ° C., and the mold is heated to 50 to 100 ° C. Into a molded product, for example, an anti-vibration material.

The foaming of the present invention preferably means that the density of the polyurethane elastomer is 0.3 to 0.7 g / cm ³ .

The anti-vibration material of the present invention is a material used for preventing vibration of automobiles, vehicles, civil engineering buildings, electrical and electronic products, mechanical devices and the like. For example, it is used as an auxiliary rubber of a vibration damping material for an automobile suspension.

[0034]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but it should not be construed that the invention is limited thereto. In the following description, “parts” and “%” are based on weight unless otherwise specified.

(A-1) MDI: "Millionate MT" manufactured by Nippon Polyurethane Industry Co., Ltd. TODI: "Trizine diisocyanate" manufactured by Nippon Soda

(A-2) Polyetherester polyol (a) Polytetramethylene glycol (molecular weight: 650), trimethylolpropane, and adipic acid are charged together, and the average number of functional groups obtained by dehydration-condensation reaction is 2.40. Polyetherester polyol having a hydroxyl value of 56.0

Polyetherester polyol (b) Polytetramethylene glycol (molecular weight: 1,000), trimethylolpropane, and adipic acid are charged at once, and the average number of functional groups obtained by dehydration condensation reaction is 2.40, and the hydroxyl value is 56.0. Polyetherester polyol

Polyetherester polyol (c) Polytetramethylene glycol (molecular weight: 2,000), trimethylolpropane, and adipic acid are charged at once, and the average number of functional groups obtained by dehydration condensation reaction is 2.40, and the hydroxyl value is 56.0. Polyetherester polyol

Polyether polyol (d) Polytetramethylene glycol (molecular weight: 2,000)

Polyester polyol (e) Average number of functional groups obtained by the dehydration condensation reaction of ethylene glycol, 1,4-butanediol and adipic acid.
00, polyester polyol having a hydroxyl value of 56.0

Polyetherester polyol (f) Polytetramethylene glycol (molecular weight: 650), 1,4-butanediol, and adipic acid are charged at once, and the average number of functional groups obtained by dehydration condensation reaction is 2.00. 56.0 polyetherester polyol

Polyetherester polyol (g) Polytetramethylene glycol (molecular weight: 650), trimethylolpropane, and adipic acid were charged at once, and the average number of functional groups obtained by the dehydration condensation reaction was 3.00, and the hydroxyl value was 70.2. Polyetherester polyol

Example 1 The NCO content of the 4,4′-diphenylmethane diisocyanate after the reaction was 6.5.
0% so that the polyester polyol (a)
Was added thereto and reacted at 80 ° C. for 30 hours in a nitrogen stream to synthesize a urethane prepolymer.

The foaming agent was 150 parts of water and a silicone-based foam stabilizer SH-193 (manufactured by Toray Dow Corning Silicone Co., Ltd.).
It was prepared by mixing 100 parts and 5 parts of triethylenediamine.

Prepolymer 1 previously heated to 80 ° C.
2 parts of a foaming agent was added to 00 parts, and the mixture was rapidly stirred at 6000 rpm for about 10 to 20 seconds, poured into a mold heated to about 80 ° C, and then aged at 80 ° C with a heating device. After aging for 40 minutes, the molded product was taken out of the mold, annealed at 110 ° C. for 15 hours, and then subjected to a density of 0.54 (g / cm ³ ) to 0.55.
(G / cm ³ ) was obtained. The compression set, compression stress, flexural durability and storage stability of this molded product were measured,
The results are shown in Tables 1 and 2.

[Examples 2 to 5] The first polyol was used.
Except for using as shown in the table, molded articles produced in the same manner as in Example 1 were evaluated, and the results are shown in Table 1.

Comparative Example 1 A prepolymer was synthesized in the same manner as in Example 1 except that the polyetherester polyol (f) was used. The molded article produced by the same method as in Example 1 was evaluated, and the results are shown in Table 2.

Comparative Example 2 A prepolymer was synthesized in the same manner as in Example 1 except that a polyetherester polyol (g) having an average functional group number of 3.0 was used, but the prepolymer was gelled during the synthesis.

Comparative Example 3 A prepolymer was synthesized in the same manner as in Example 1 except that the polyether polyol (d) was used. The molded article produced by the same method as in Example 1 was evaluated, and the results are shown in Table 2.

Comparative Example 4 A prepolymer was synthesized in the same manner as in Example 1 except that the polyester polyol (e) was used. The molded article produced by the same method as in Example 1 was evaluated, and the results are shown in Table 2.

Comparative Example 5 3,3′-dimethyl-4,
4'-biphenylenediisocyanate added with NC after reaction
All except that the urethane prepolymer was synthesized by adding the above-mentioned adipic acid-based polyester polyol (e) having an average functional group number of 2.0 so that the O content became 4.50% and reacting at 80 ° C. for 30 hours in a nitrogen stream. The molded article produced by the same method as in Example 1 was evaluated, and the results are shown in Table 2.

<Physical Property Test> (1) Compression Set (Compliant with JIS K-6301) The compression set after heat treatment at 80 ° C. for 70 hours under 25% compression was measured.

(2) Compressive stress A sample having an outer diameter of 28 mm and a thickness of 12.7 mm was compressed at a compression speed of 5 mm.
3rd time when 60% compression was repeated 3 times at mm / min
The stress at 0% compression was measured.

(3) Flexural Durability A 150 mm long, 25 mm wide, 6 mm thick sample was subjected to a durability test using a dematcher bending tester, and the number of times until cracks, cracks, and cracks occurred was measured.

(4) Moldability The state of the elastomer at the time of demolding and the shape of the elastomer after demolding and after secondary curing are visually confirmed.

：: State in which no deformation, swelling, cracking, or crack has occurred. ×: State in which deformation, swelling, cracking, or cracking is observed.

(5) Storage Stability NCO% was measured before and after the isocyanate-terminated prepolymer was heated at 100 ° C. for 24 hours, and the storage stability was evaluated according to the following formula.

The lower the storage stability (%), the better the stability.

[0059]

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

The present invention relates to a foamed polyurethane elastomer using MDI, which comprises a triol compound (A-2-
1) By using a polyetherester polyol having a specific average functional group number consisting of polyoxyalkylene glycol (A-2-2) and an aliphatic dibasic acid as a raw material, compression set is small and sufficient resistance is obtained. It has loadability and excellent storage stability of prepolymer.
Since an inexpensive foamed polyurethane elastomer excellent in molding workability can be obtained, it is highly useful in many industrial fields such as vibration insulators.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // (C08G 18/42 101: 00) C08L 75:04

Claims (4)

[Claims] 1. An isocyanate-terminated prepolymer (A) comprising (A-1) an isocyanate and (A-2) a polyol component.
And a foaming polyurethane elastomer composition comprising water, a foam stabilizer and a foaming component (B) comprising a catalyst, wherein (A-1) is 4,4′-diphenylmethane diisocyanate, and (A-2) is (A-2-1) triol compound, (A-2-2) polyoxyalkylene glycol, (A-2-3) average number of functional groups consisting of aliphatic dibasic acid 2.1 to 2.
5. A foamed polyurethane elastomer composition comprising an isocyanate group-terminated urethane prepolymer (A) comprising a polyol containing the polyetherester polyol of item 5. 2. The foamed polyurethane elastomer composition according to claim 1, wherein the average molecular weight of the polyetherester polyol in the polyol (A-2) is from 1500 to 4000. 3. (A-1) / (A-2) = NC of prepolymer (A)
The foamed polyurethane elastomer composition according to claim 1, wherein the O / OH (equivalent ratio) is from 1.6 / 1 to 5.0 / 1. 4. A vibration damping material comprising the foamed polyurethane elastomer composition according to any one of claims 1 to 4.