JP3783796B2 - Foamed polyurethane elastomer composition - Google Patents

Description

【００４８】
【表１】

【００４９】
【表２】

【００５０】
【発明の効果】
本発明は、ＭＤＩを使用した発泡ポリウレタンエラストマーにおいて、特定の平均官能基数を有するポリエステルポリオールを原料とすることにより、プレポリマーの貯蔵安定性に優れ、圧縮永久歪が小さく且つ充分な圧縮応力を有した安価な発泡ポリウレタンエラストマーを得ることができるため、防振材等多くの産業分野で利用価値が高いものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foamed polyurethane elastomer composition having excellent storage stability of a prepolymer, a small compression set and a sufficient compressive stress.
[0002]
[Prior art]
Foamed polyurethane elastomers are widely used as auxiliary rubbers and cushioning materials for vibration damping materials for automobile suspensions because of their excellent elastic recovery and mechanical strength. Conventionally, foamed polyurethane elastomers having excellent performance include 1,5-naphthylene diisocyanate (hereinafter abbreviated as NDI), 3,3′-dimethyl-4,4′-biphenylene diisocyanate (hereinafter abbreviated as TODI) and polyester. It is produced by mixing and foaming / curing an isocyanate group-terminated prepolymer obtained by reacting a polyol with a foaming agent comprising water, a catalyst and a silicone foam stabilizer.
[0003]
However, the one using the above NDI or TODI has small performance when repeatedly subjected to compression set or high load, and has excellent performance such as having sufficient compressive stress, but the prepolymer pot life is short. In addition, there is a disadvantage that NDI and TODI are very expensive, as well as disadvantages such as large thickening with time and poor storage stability. In addition, when the isocyanate is replaced with inexpensive 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), an excellent storage stability and good workability can be obtained, but as in the case where conventional NDI or TODI is used. Small compression set and sufficient compressive stress cannot be obtained. Various studies have been conducted to obtain a polyurethane foam elastomer that eliminates the disadvantages caused by using such MDI.
[0004]
For example, JP-A-7-224139 discloses a compression permanent having excellent mechanical properties obtained by reacting with a foaming agent comprising an isocyanate group-terminated prepolymer, water, a low molecular weight diol, and a polyether polyol having a number average molecular weight of 5,000 to 10,000. Proposals have been made on micro-foamed polyurethane elastomers with low distortion. However, in this case, the compatibility of water and the polyether polyol in the foaming agent is not necessarily good, and physical properties are expected to deteriorate due to uneven reaction and foaming.
[0005]
Japanese Patent Application Laid-Open No. 7-252340 has proposed a micro-foamed polyurethane elastomer obtained by foaming and curing an isocyanate-terminated prepolymer, a hydroxyl-terminated prepolymer and a foaming component using MDI. TODI is used for the diisocyanate component used in the polymer, and an inexpensive fine cell foamed polyurethane elastomer cannot be obtained. In this case, since the hydroxyl group-terminated prepolymer is contained in the foaming agent, it is considered that the crosslinking and curing reaction is slow and it takes a long time for demolding, resulting in a decrease in workability.
[0006]
Japanese Patent Application Laid-Open No. 61-250019 discloses a high-load repeated compression from a copolymer of polytetramethylene glycol and ε-caprolactone, a terminal NCO prepolymer obtained from MDI, and a foaming agent mainly composed of water. There is an example of producing a microcellular polyurethane elastomer which is a vibration-proof material that can sufficiently withstand the heat resistance and is excellent in cold resistance and wet heat hydrolysis resistance. However, even in this case, sufficiently satisfactory performance cannot always be obtained as compared with those using NDI or TODI.
[0007]
Further, JP-A-60-235824 discloses an adipate in which ethylene glycol (EG) and butylene glycol are adjusted so that the mixing ratio (EG / BG) thereof is 70/30 to 30/70. Although there is a proposal regarding a urethane elastomer sponge characterized by containing 2-bis (4′-oxyphenyl) propane, the adipate has a content of 2,2-bis (4′-oxyphenyl) propane. The viscosity of the resulting prepolymer is high, and cracks may occur during foaming / curing.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a foamed polyurethane elastomer composition having excellent storage stability of a prepolymer, a small compression set and a sufficient compressive stress when an inexpensive MDI is used.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to achieve these objects, the present inventors have found a quantitative relationship between the average number of functional groups of the polyester polyol of the terminal isocyanate group prepolymer, which is a raw material of the foamed polyurethane elastomer, and the compression set. By discovering and using polyester polyols with an average functional group number of 2.1 to 2.4, when using inexpensive MDI, the prepolymer has excellent storage stability, low compression set and sufficient compression It has been found that a foamed polyurethane elastomer having a stress can be obtained, and the present invention has been completed.
[0010]
That is, the present invention relates to (A) a terminal isocyanate group prepolymer obtained from 4,4′-diphenylmethane diisocyanate and a polyester polyol having an average functional group number of 2.1 to 2.4, and (B) water and a foam stabilizer. And a foamed polyurethane elastomer composition characterized by having a density of 0.3 (g / cm ³ ) to 0.7 (g / cm ³ ), Provides a foamed polyurethane elastomer composition characterized in that the NCO / OH (equivalent ratio) of the prepolymer (A) is 1.6 / 1 to 5.0 / 1.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The component (A) of the present invention mainly uses 4,4′-diphenylmethane diisocyanate, but other diisocyanates may be used in combination as long as the effects of the present invention are not impaired. , Cycloaliphatic, and aliphatic, for example, 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, 4,4'-diphenylmethane diisocyanate, o-tolidine diisocyanate, p-phenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate , Hydrogenated Diphenylmethane diisocyanate, can be mentioned cyclohexane diisocyanate, but are not limited thereto.
[0012]
The polyester polyol of component (A) of the present invention is composed of an acid component and a short-chain polyol component. The short-chain polyol component is preferably used by mixing a short-chain diol and a short-chain triol. Preferred examples include aliphatic short-chain diols and short-chain triols having 2 to 18 carbon atoms. Examples of the short-chain diol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-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, etc. The above can be used. Examples of the short-chain triol include glycerin, trimethylolpropane, trimethyloloctane, and the like, and these can be used alone or in combination of two or more.
[0013]
The mixing ratio of the short chain diol and the short chain triol is used by mixing a predetermined amount in accordance with the target average functional group number.
[0014]
The acid component is preferably a dibasic acid, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid. An aliphatic dibasic acid such as dimer acid, hydrogenated dimer acid or the like can be used alone or in combination of two or more.
[0015]
Polyester polyols obtained by ring-opening polymerization of lactones using a mixture of short-chain triols and short-chain diols as a reaction initiator can also be used as long as the average number of functional groups is in the range of 2.1 to 2.4. is there.
[0016]
Furthermore, the polyester polyol used in the present invention can be used by mixing a polyol having an average functional group number of 2.0 and a polyol having an average functional group number of 3.0, but the average functional group number of the mixture is 2 It is necessary to be adjusted to the range of .1 to 2.4.
[0017]
If the average functional group number of the polyester polyol is less than 2.1, the compression set of the obtained polyurethane foam elastomer becomes large and cannot be practically used. On the other hand, if the average number of functional groups exceeds 2.4, a gel product is generated due to three-dimensional crosslinking in the stage of synthesizing the terminal isocyanate group prepolymer, or the viscosity of the prepolymer becomes remarkably high and the mixing state with the foaming agent is poor. Cracks occur during molding.
[0018]
As the polyester polyol of the component (A) of the present invention, a normal polyester polyol production technique can be used. For example, a method of reacting these short-chain polyols and dibasic acid under normal pressure, a method of esterification under vacuum, a reaction by esterifying in the presence of an inert solvent such as toluene and azeotropically condensing water with the solvent A method of removing out of the system can be used. The esterification reaction can be performed even in a system in which no catalyst is present. Usually, in order to promote esterification smoothly, for example, acids such as inorganic acids and organic acids, Li, Na, K, Mg, Al, Ca, Ti , V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Pb, Sr, Zr, Pd, Sn, and other metal chlorides, oxides, hydroxides, acetic acid, oxalic acid of the above metals, Fatty acid metal salts such as octylic acid, lauric acid, naphthenic acid, sodium methylate, sodium ethylate, aluminum tetraisopropoxide, isopropyl titanate, alcoholate such as n-butyl titanate, phenolate such as sodium phenolate, Al, Ti, All used for normal esterification and transesterification reactions of organometallic compounds of metals such as Zn, Zr, Sn, Pb It can be used in the catalyst. The amount of catalyst added is in the range of about 0.0001% to 5% by weight, preferably in the range of about 0.002% to 2% by weight, based on the total weight of the raw materials used. . The reaction temperature is preferably 160 ° C to 250 ° C.
[0019]
As a means for obtaining a terminal isocyanate group prepolymer from the polyester polyol and MDI as component (A), conventional known production methods can be used. At this time, the equivalent ratio of the diisocyanate to the polyester polyol used is preferably NCO / OH = 1.6 to 5.0. When the NCO / OH ratio is less than 1.6, the viscosity of the isocyanate group-terminated prepolymer increases and the workability decreases. When the NCO / OH ratio exceeds 5.0, the resulting foamed polyurethane elastomer Elasticity is impaired and it cannot endure practicality.
[0020]
The ratio of the isocyanate group equivalent of the isocyanate group-terminated prepolymer (A) of the present invention to the hydroxyl group equivalent in the blowing agent (B) is preferably adjusted in the range of 1.0 / 0.9 to 1.0 / 1.1. There is a need to. If it deviates from the above range, the physical properties and durability of the obtained polyurethane foam elastomer are lowered. The amount of water contained in the foaming agent is not particularly limited, but the ratio of the isocyanate group-terminated prepolymer and the foaming agent is preferably adjusted and used so that the weight ratio is in the range of 100: 1 to 50. .
[0021]
The water used in the foaming agent (B) of the present invention is preferably pure water or ion exchange water. As the catalyst, known organometallic 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 organometallic compounds such as dibutyltin dilaurate and dibutyltin oxide. Etc. are specifically mentioned. Furthermore, the foam stabilizer is preferably a silicone-based surfactant, and known ones such as SH-193 (Toray Dow Corning Silicone) can be used.
[0022]
As the foaming agent (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.).
[0023]
The foaming agent (B) of the present invention may contain an auxiliary agent as necessary in addition to water, a foam stabilizer and a catalyst. Examples of such auxiliaries include antioxidants, ultraviolet absorbers and flame retardants.
[0024]
The operation of mixing and stirring the above-mentioned foaming agent and the above-mentioned isocyanate-terminated prepolymer into the mold and injection-molding into the mold can be sufficiently performed by a known technique.
[0025]
The foaming of the present invention preferably means that the density of the polyurethane elastomer is 0.3 to 0.7 g / cm ³ .
[0026]
Hereinafter, the present invention will be specifically described by way of examples, but is not limited thereto. In the text, “parts” and “%” indicate weight standards unless otherwise specified.
[0027]
【Example】
[Synthesis Example 1]
<Synthesis of Polyester Polyol A with an Average Functional Group Number of 2.15>
417.7 parts of ethylene glycol, 10.2 parts of trimethylolpropane, 893.5 parts of adipic acid and 0.033 part of tetraisopropyl titanate as a catalyst were charged all at once into a reaction vessel, and the mixture was stirred at 200 ° C. in a nitrogen stream. The reaction was carried out for 20 hours while distilling off the water produced in step 1 to obtain polyester polyol A having the following properties.
[0028]
Acid value: 0.32
Hydroxyl value: 53.28
[0029]
[Synthesis Example 2]
<Synthesis of Polyester Polyol B with 2.30 Average Functional Groups>
A reaction vessel was charged with 410.7 parts of ethylene glycol, 19.7 parts of trimethylolpropane, 889.7 parts of adipic acid and 0.033 parts of tetraisopropyl titanate as a catalyst, and was stirred at 200 ° C. in a nitrogen stream. The reaction was carried out for 20 hours while distilling off the water produced in step 1 to obtain polyester polyol B having the following properties.
Acid value: 0.32
Hydroxyl value: 55.91
[0030]
[Synthesis Example 3]
<Synthesis of Polyester Polyol C with Average Functional Group Number 2.00>
A reaction vessel was charged with 427.9 parts of ethylene glycol, 890.0 parts of adipic acid and 0.039 parts of tetraisopropyl titanate as a catalyst, and the water produced at 200 ° C. was distilled off under stirring in a nitrogen stream. Then, the reaction was carried out for 20 hours to obtain a polyester polyol C having the following properties.
Acid value: 0.10
Hydroxyl value: 56.10.
[0031]
[Synthesis Example 4]
<Synthesis of Polyester Polyol D with Average Functional Group Number 2.00>
A reaction vessel was charged with 213.5 parts of ethylene glycol, 310.0 parts of 1,4-butanediol, 890.0 parts of adipic acid, and 0.034 parts of tetraisopropyl titanate as a catalyst. The reaction was carried out for 20 hours while distilling off the water produced at 200 ° C. to obtain polyester polyol D having the following properties.
Acid value: 0.10
Hydroxyl value: 56.90
[0032]
[Synthesis Example 5]
<Synthesis of Polyester Polyol E with Average Functional Group Number 2.50>
A reaction vessel was charged with 417.2 parts of ethylene glycol, 29.7 parts of trimethylolpropane, 903.3 parts of adipic acid and 0.034 parts of tetraisopropyl titanate as a catalyst. The reaction was carried out for 20 hours while distilling off the water produced in step 1 to obtain polyester polyol E having the following properties.
[0033]
Acid value: 0.27
Hydroxyl value: 59.87
[0034]
[Synthesis Example 6]
<Synthesis of Polyester Polyol F with Average Functional Group Number 3.00>
A reaction vessel was charged with 401.1 parts of ethylene glycol, 49.3 parts of trimethylolpropane, 899.6 parts of adipic acid, and 0.034 parts of tetraisopropyl titanate as a catalyst. The reaction was carried out for 20 hours while distilling off the water produced in step 1 to obtain polyester polyol F having the following properties.
Acid value: 0.12
Hydroxyl value: 58.37
[0035]
[Example 1]
80,99 parts of the above polyester polyol A was added to 296.0 parts of 4,4'-diphenylmethane diisocyanate and reacted at 80 ° C for 30 hours in a nitrogen stream to synthesize a urethane prepolymer having an NCO content of 6.00%.
[0036]
The foaming agent was prepared by mixing 150 parts of water, 100 parts of a silicone foam stabilizer SH-193 (manufactured by Toray Dow Corning Silicone) and 5 parts of triethylenediamine.
[0037]
2 parts of a foaming agent is added to 100 parts of the prepolymer previously heated to 80 ° C., stirred at 6000 rpm for about 10 to 20 seconds at high speed, poured into a mold heated to about 80 ° C., and then heated at 80 ° C. Aged with. After aging for 40 minutes, the molded product was taken out from the mold and annealed at 110 ° C. for 15 hours, and a molded product having a density of 0.54 (g / cm ³ ) to 0.55 (g / cm ³ ) was obtained. The compression set and compression stress of this molded product were measured, and the results are shown in Table 1.
[0038]
[Example 2]
Except for using polyester polyol B, all molded articles produced by the same method as in Example 1 were evaluated, and the results are shown in Table 1.
[0039]
[Comparative Example 1]
Except for using polyester polyol C, molded articles produced by the same method as in Example 1 were evaluated, and the results are shown in Table 1.
[0040]
[Comparative Example 2]
Except for using polyester polyol E, molded articles were produced by the same method as in Example 1, but cracks occurred frequently.
[0041]
[Comparative Example 3]
A prepolymer was synthesized in the same manner as in Example 1 except that polyester polyol F was used, but gelled during synthesis.
[0042]
[Comparative Example 4]
Urethane having an NCO content of 4.43% by adding 800.0 parts of the above polyester polyol C to 252.0 parts of 3,3′-dimethyl-4,4′-biphenylene diisocyanate and reacting at 80 ° C. for 30 hours in a nitrogen stream. Except for the synthesis of the prepolymer, all molded articles produced by the same method as in Example 1 were evaluated. The results are shown in Table 2.
[0043]
[Comparative Example 5]
Except for using polyester polyol D, all molded articles produced by the same method as in Comparative Example 4 were evaluated, and the results are shown in Table 2.
[0044]
<Physical property test>
(1) Compression set (conforming to JIS K-6301)
(1) The compression set after heat treatment at 25% compression at 80 ° C. for 70 hours was measured.
(2) The compression set after heat treatment at 25% compression at 100 ° C. for 70 hours was measured.
[0045]
(2) Compression stress 60% of sample with outer diameter of 28mm and thickness of 12.7mm at compression speed of 5mm / min
The stress at the time of 60% compression when the compression was repeated three times was measured.
[0046]
(3) Storage stability of prepolymer After the isocyanate-terminated prepolymer was heated at 100 ° C. for 24 hours and before treatment, NCO% was measured, and the storage stability was evaluated according to the following formula.
[0047]

[0048]
[Table 1]

[0049]
[Table 2]

[0050]
【The invention's effect】
The present invention is a foamed polyurethane elastomer using MDI. By using a polyester polyol having a specific average number of functional groups as a raw material, the prepolymer has excellent storage stability, a small compression set, and a sufficient compressive stress. Therefore, it is possible to obtain an inexpensive foamed polyurethane elastomer, which has high utility value in many industrial fields such as a vibration isolator.

Claims (2)

(A) a terminal isocyanate group prepolymer obtained from 4,4′-diphenylmethane diisocyanate and a polyester polyol having an average functional group number of 2.1 to 2.4;
(B) It is obtained from a foaming agent comprising water, a foam stabilizer and a catalyst , and the density thereof is 0.3 (g / cm ³ ) to 0.7 (g / cm ³ ). A foamed polyurethane elastomer composition.   The foamed polyurethane elastomer composition according to claim 1, wherein the prepolymer (A) has an NCO / OH (equivalent ratio) of 1.6 / 1 to 5.0 / 1.