JPH0733425B2 - Polyurethane foam elastomer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyurethane foamed elastomer, more specifically, paraphenylene diisocyanate (hereinafter referred to as PPDI).
Abbreviated as “) and an aliphatic / aromatic copolyester polyol having an isocyanate group at the end as a urethane prepolymer and an amine-based catalyst, an aliphatic oxycarboxylic acid-based catalyst, and a surfactant. The present invention relates to a polyurethane foam elastomer (hereinafter abbreviated as foam elastomer) applicable to products repeatedly used under high compression conditions.

[Conventional technology]

Foamed elastomers are widely used as products used under repeated high compression conditions such as spring elements for automobile suspension. The reason for this is that spring characteristics can be easily obtained according to the purpose, and it is also effective in reducing the weight of automobiles.

Foamed elastomers with excellent performance include 1,5-
Naphthalene diisocyanate (hereinafter abbreviated as 1,5-NDI) and an aliphatic polyester polyol, which is obtained from a urethane prepolymer having an isocyanate group at the end and a castor oil-based blowing agent, trizine diisocyanate (hereinafter abbreviated as TODI) And a castor oil-based foaming agent, and a urethane prepolymer having an isocyanate group at the end thereof, which is obtained from an aliphatic polyester polyol.

However, the urethane prepolymers having isocyanate groups at the ends that are used for these foamed elastomers have relatively high viscosities in both 1,5-NDI and TODI systems, so they can be mixed with a foaming agent to obtain proper foams. The liquid temperature of the urethane prepolymer must be adjusted to 100 to 140 ° C.
The urethane prepolymer has a property that an isocyanate group and a urethane group react with each other to cause a side reaction to generate an allophanate group and the like. This side reaction has an effect of improving the performance of the polyurethane in a proper case, but when it becomes excessive, not only the performance is impaired, but also the foaming reaction itself cannot be performed due to thickening. The side reaction is more likely to proceed as the liquid temperature increases.

Due to these properties of urethane prepolymer, 1,5-ND
I-type and TODI-type urethane prepolymers have high viscosity and can be foamed only when the liquid temperature is high.
It has the drawback that the usable time is short.

Therefore, in order to obtain the desired polyurethane foam, it is necessary to synthesize a urethane prepolymer on a small scale of about several tens and to immediately provide it for foaming, which is not always good in working efficiency.

[Problems to be Solved by the Present Invention]

The conventional drawback is due to the high viscosity of urethane prepolymers having isocyanate groups at the ends, and as a result of extensive studies based on the idea that lowering the viscosity is effective. , As isocyanate
The present invention has been found to be improved by using PPDI and a specific copolyester polyol.

[Means for solving problems]

That is, the present invention uses a urethane prepolymer having an isocyanate group at the end, which is an aliphatic / aromatic copolyester polyol containing PPDI and two or more active hydrogens, as a foaming agent for an amine-based catalyst or an aliphatic oxycarboxylic acid-based catalyst. And a polyurethane foam elastomer obtained by foaming with an aqueous solution containing a sulfated product of a fatty acid.

The urethane prepolymer having an isocyanate group at the end in the present invention comprises PPDI and an aliphatic / aromatic copolyester polyol. This urethane prepolymer has a lower viscosity than 1,5NDI-based and TODI-based urethane prepolymers, and it is possible to lower the liquid temperature of the urethane prepolymer in the foaming process. As a result, the usable time is shortened. Not only can it be made longer, but it is also possible to use it after solidifying once and then reheating and melting. Therefore, the urethane prepolymer can be synthesized on a large scale and used in the required amount or can be solidified and stored until the required time, so that the effect is great in the field where the foamed elastomer is produced. Among the raw materials used in the present invention, PPDI is a compound that has a melting point of 95 ° C. and is a solid at room temperature, and its chemical structure has a symmetric structure as shown in formula (1). It is known that the compound exhibits high performance, that is, high tensile strength, high elasticity and heat resistance. And, more advantageously, the isocyanate-terminated urethane prepolymer synthesized by using this PPDI has a constant molar ratio of diisocyanate and polyols such as polyester polyol and / or polyether polyol, It has been found to have a lower viscosity than urethane prepolymers made with 1,5-NDI and / or TODI.

For this reason, when using 1,5-NDI-based and TODI-based urethane prepolymers, the prepolymer temperature must be 100 ° C. or higher.
It has become possible to achieve a significantly lower temperature of ~ 80 ° C compared to the past.

Polyester polyols used in conventional foamed elastomers composed of 1,5-NDI, TODI, etc. are aliphatic diols such as ethanediol and 1,4 butanediol and aliphatic dibases such as succinic acid and adipic acid. The polyester polyol used in the present invention is an aliphatic / aromatic copolyester polyol, which is a so-called aliphatic polyester polyol composed of acids.

The foamed elastomer according to the present invention is intended to be repeatedly used under a high compression condition, but basically, in the foamed elastomer produced by a decarboxylation reaction by a reaction between water and an isocyanate, its intended purpose is to be used. Therefore, appropriate hardness and elasticity are required. In order to achieve this target performance, it is extremely effective to introduce an aromatic ring on the polyol side in addition to the aromatic polyisocyanate in the bone core of the foamed elastomer. The aromatic ring is preferably introduced into the polyester polyol as an aromatic diol and / or an aromatic dibasic acid to form an aliphatic / aromatic copolyester polyol, but in the foaming step, the aromatic diol is used together with the foaming agent. Kinds can also be introduced.

The aliphatic / aromatic copolyester polyols of the present invention are
It has an average molecular weight of 500 to 5000, preferably 1000 to 2500, and includes ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2, 2'-Dimethyl 1,3-propanediol, diethylene glycol, 1,5-pentanediol, 3-methyl-1,5
-Pentanediol, 1,6-hexanediol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol and other aliphatic diols and bishydroxyethoxybenzene, bisphenol A, bisphenol A ethylene oxide or propylene oxide addition body,
Aromatic diols such as paraxylylene diol, and mixtures thereof, and aliphatic dibasic acids such as succinic acid, maleic acid, adipic acid, glutaric acid, suberic acid, azelaic acid, and sebacic acid, and phthalic acid and isophthalic acid. It can be obtained from an aromatic dibasic acid such as an acid or terephthalic acid, or a mixture thereof. The content of aromatic compounds in the aliphatic / aromatic copolyester polyol is 5-40
It is mol%, preferably 8 to 30 mol%. Amine-based catalysts have high catalytic activity for resinification reaction and foaming reaction in polyurethane foam production, and have good surface curability in mold formulation and fine cell structure moldability. It is effective for obtaining molded products with excellent characteristics. Examples of such amine-based catalysts include diethylamine, triethylamine, triethylenediamine,
Examples include piperazine pentamethyldiethylenetriamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine, dimethylethanolamine, ethylmorpholine, bis-2-dimethylaminoethyl ether, trimethylaminoethylpiperazine, and methylhydroxyethylpiperazine. The aliphatic oxycarboxylic acid catalyst controls the resinification reaction and the foaming reaction in a well-balanced manner in the process from the injection of the mixture of the urethane prepolymer and the foaming agent into the mold to the demolding in the foaming process, and it is excellent. It is effective for obtaining a foamed elastomer. Examples of the aliphatic oxycarboxylic acid catalysts include glycolic acid, lactic acid, citric acid, isocitric acid, glyceric acid, tartaric acid,
There are oxycarboxylic acids such as malonic acid and malic acid.

Amine-based catalysts and aliphatic oxycarboxylic acid-based catalysts are
It may be added to the urethane prepolymer immediately before the foaming work, but a method of adding it to the foaming agent is preferable.

The foaming agent is an aqueous solution containing an active surface active agent obtained by sulfating a fatty acid such as ricinoleic acid, and a commercially available one can be used. As an example of such a foaming agent, Additive SV (Sumitomo Bayer Urethane Co., Ltd.)
And Rohto Oil 40 (made by Ito Oil Co., Ltd.).

The foamed elastomer in the present invention, as described above,
It is obtained by mixing a predetermined amount of a urethane prepolymer having an isocyanate group at the end with a predetermined amount of a castor oil-based foaming agent, and injecting the mixture into a predetermined mold. At this time, the liquid temperature of the urethane prepolymer is 50 to 90 ° C, preferably 6
The foaming agent temperature may be 10 to 30 ° C. The mold temperature is 50 to 100 ° C, preferably 60 to 80 ° C, but adjustment of the mold temperature is important to obtain an excellent foamed elastomer. After injecting the mixture of urethane prepolymer and blowing agent into the mold, 90 ~ 140 ℃, preferably 110 ~ 130 ℃
After curing for 10 to 40 minutes, preferably 15 to 30 minutes in the curing oven, demolding, and secondary curing at 100 to 130 ° C., the foamed elastomer of the present invention can be obtained.

Further, the urethane prepolymer of the present invention can obtain a foamed elastomer having no problem even if it is allowed to stand for several hours at an adjusted temperature for foaming.
After synthesizing the urethane prepolymer, it is cooled and solidified, left to stand in a room for a long time under N ₂ tightness, and then reheated for foaming to obtain a foamed elastomer having predetermined properties. As described above, the foamed elastomer comprising the urethane prepolymer obtained from PPDI and the aliphatic / aromatic copolyester polyol, the amine-based catalyst, the aliphatic oxycarboxylic acid-based catalyst, and the castor oil-based blowing agent in the present invention has been conventionally used. Not only was the foaming process made much more efficient, but it also exhibited excellent resilience in repeated high compression tests.

〔Example〕

Next, a more detailed description will be given with reference to examples. "Parts" and "%" in the examples are "parts by weight" and "% by weight" unless otherwise specified. The polyester polyol, urethane prepolymer and foaming agent used in all examples are as follows.

(1) Polyester polyol Polyester (A) Ethanediol (hereinafter abbreviated as EG) / 1,4-butanediol (hereinafter abbreviated as 1,4-BG) / Adipic acid (hereinafter abbreviated as AA)
= 0.66 / 0.44 / 1.00 (molar ratio), an aliphatic polyester polyol obtained by a general polyether synthesis method.

Polyester (B) Bishydroxyethoxybenzene (hereinafter abbreviated as BHEB) / E
G / 1,4BG / AA = 0.74 / 0.66 / 0.44 / 1.00 (molar ratio) Aliphatic / aromatic copolyester polyol obtained by conventional polyester synthesis method Polyester (C) BHEB / EG / 1,4BG / AA = 0.31 / 0.66 / 0.44 / 1.00 (molar ratio)
And an aliphatic / aromatic copolyester polyol obtained by a normal polyester synthesis method (2) Urethane prepolymer having an isocyanate group at the end Prepolymer (A) PPDI / polyester (A) = 2/1 (molar ratio) Prepolymer (B) PPDI / polyester (B) = 2/1 (molar ratio) obtained by the conventional prepolymer synthesis method, and the prepolymer obtained by the conventional prepolymer synthesis method C) PPDI / polyester (C) = 2/1 (molar ratio), prepolymer obtained by a general prepolymer synthesis method Prepolymer (D) 1,5-NDI / polyester (A) = 2/1 ( Prepolymer obtained by a conventional prepolymer synthesis method at a molar ratio) Prepolymer (E) TODI / polyester (A) = 2/1 (molar ratio) Prepolymer obtained by (3) with respect to the foaming agent foaming agent (A) additive SV (manufactured by Sumitomo Bayer Urethane Co.) blowing agent (B) additive SV100 parts, triethylenediamine 1
Partial tartaric acid 0.5 part foaming agent The above urethane prepolymer and foaming agent were used to formulate (a) 150 × 150 × 10 5 according to the examples and comparative examples.
(Mm) foam sheet, and (b) outer diameter 50, inner diameter 18, height
A 60-mm cylindrical foamed molded product was obtained. The foam sheet of (a) was used for evaluation of mechanical properties, and the molded product of (b) was used for evaluation of performance by repeated compression test. The mechanical properties were measured according to JIS K6301. The repeated compression test was performed under the following conditions using a hydraulic servo fatigue tester manufactured by Sagimiya Manufacturing Co., Ltd.

[Repeated compression test conditions]

Load: 500 kg Compression cycle: 2 Hertz Number of repeated compressions: 300,000 Examples 1,2 Using the prepolymer and the foaming agent shown in Table 1, the mixture was made into gold at the mold temperature and prepolymer temperature shown in Table 1. After injecting into the mold and curing, the mold was removed, and then secondary curing was carried out at 120 ° C. for 10 hours to obtain a foamed elastomer. The mechanical properties are shown in Table 2, and the repeated compression test results are shown in Table 3.

Example 3 After synthesizing the prepolymers in Table 1, the mixture was allowed to stand at 75 ° C. for 3 hours, and then a foamed elastomer was obtained with the same formulation as in Example 1. The mechanical properties are shown in Table 2. Table 3 shows the results of repeated compression tests.
Shown in.

Example 4 After synthesizing the prepolymers shown in Table 1, the prepolymers were once cooled and solidified, allowed to stand at room temperature for 1 week under N ₂ tightly sealed, and then heated and dissolved again.
A foamed elastomer was obtained with the prepolymer temperature of 75 ° C. and the same formulation as in Example 2. The mechanical properties are shown in Table 2. The results of the repeated compression test are shown in Table 3.

Comparative Example 1 Using the prepolymer and the foaming agent shown in Table 1, the mixture was poured into the mold at the mold temperature and the prepolymer temperature and then cured to remove the mold.
Secondary curing was carried out at 10 ° C for 10 hours to obtain a foamed elastomer. The mechanical properties are shown in Table 2. Table 3 shows the results of repeated compression tests.
Shown in.

Comparative Example 2 After synthesizing the prepolymer (D), the mixture was allowed to stand at 110 ° C. for 5 hours, and then the mixture was poured into the mold at the mold temperature and the prepolymer temperature with the prepolymer and the foaming agent shown in Table 1 and cured. Attempting to obtain a foamed elastomer by demolding and secondary curing at 120 ° C for 10 hours, the specified foamed elastomer could not be obtained, probably because the viscosity of the prepolymer increased.

Comparative Example 3 A mixture of the prepolymer and the foaming agent shown in Table 1 was poured into the mold at a mold temperature and a prepolymer temperature and then cured at 120 ° C. for 30 minutes, but a foamed elastomer having a predetermined shape could not be obtained. It seems that the combination of the prepolymer (E) and the foaming agent (A) has an improper balance between the resinification reaction and the foaming reaction.

In Comparative Examples 2 and 3, the foams having a predetermined shape could not be obtained, so that the tests shown in Tables 2 and 3 could not be performed.

〔The invention's effect〕

The performance of the polyurethane foam according to the present invention is comparable to that of the conventional product, and the conventional technique can be remarkably improved in efficiency in the manufacturing process. Therefore, the practical effect is extremely large.

Claims (1)

[Claims] 1. A urethane type prepolymer having an isocyanate group at the terminal, which is composed of an aliphatic / aromatic cobalt ester polyol containing para-phenylene diisocyanate and two or more active hydrogens, is used as a blowing agent for an amine catalyst and an aliphatic oxycarboxylic acid catalyst. A polyurethane foam elastomer obtained by foaming using an aqueous solution containing a catalyst and a sulfated product of a fatty acid.