JPH0368620A - Production of highly resilient polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a resilient polyurethane foam excellent in the impact resilience and wet heat compression set by reacting a specific polyol with a specific polyisocyanate in the presence of a blowing agent, a catalyst, etc. CONSTITUTION:In a process for producing a resilient polyurethane foam by reacting a polyol with a polyisocyanate in the presence of a blowing agent, a cell regulator, a catalyst, and other necessary auxiliaries, a mixture of a high-mol.-wt. polyoxyalkylene polyol having a hydroxyl number of 5-26 and a total unsaturation of 0.07 or lower (e.g. a polyoxyalkylene polyol obtd. by reacting glycerin with propylene oxide and then with ethylene oxide) with a low-mol.-wt. isocyanate-reactive polyfunctional compd. (e.g. a compd. obtd. by reacting sorbitol with propylene oxide and then with ethylene oxide) as the polyol and a mixture of tolylene diisocyanate with a polymethylene polyphenylene polyisocyanate as the polyisocyanate are used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a high resilience polyurethane foam.

[Prior Art] Conventionally, polyurethane elastic foams have been manufactured from polyoxyalkylene polyols and polyisocyanates with a hydroxyl value of about 56, but the impact resilience is about 40%.
A foam with even better rebound resilience has a hydroxyl value of 28.
There are foams made from ~34 polyoxyalkylene polyols and polyisocyanates, but the impact resilience is 60-70%, and a foam with impact resilience of 70-80% or even over 80% has not yet been obtained. .

[Problems to be solved by the invention] Conventionally, high impact resilience foams are manufactured from polyoxyalkylene polyols and polyisocyanates with a hydroxyl value of about 28 to 34, but the impact resilience is 60 to 70%, exceeding 75%. I couldn't get the form. In order to achieve such a goal, it is possible to lower the hydroxyl value of polyoxyalkylene polyol and increase its molecular weight, but as the degree of unsaturation increases, physical properties other than impact resilience, such as thermal compression set properties, may decrease. Furthermore, there was a major problem in that the impact resilience did not improve proportionally as the molecular weight increased.

In view of these points, as a result of intensive study on the combination of the molecular structure of polyoxyalkylene polyol and the structure of polyisocyanate, we found that the combination of the molecular structure of polyoxyalkylene polyol and the structure of polyisocyanate resulted in a hydroxyl value of 5 to 26 and a degree of unsaturation of 0.
．． By using a mixture of a high molecular weight polyoxyalkylene polyol of 0.07 or less and a polyfunctional compound having a low molecular weight isocyanate-reactive group in combination with a mixture of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate, the impact resilience is 75%. The present invention was completed by discovering that polyurethane foam exceeding the above can be produced.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and consists of combining a polyol and a polyisocyanate compound with a blowing agent,
In the method of producing polyurethane elastic foam by reacting in the presence of a foam stabilizer, a catalyst and other auxiliaries, a high molecular weight polyoxyalkylene polyol having a hydroxyl value of 5 to 26 and a total unsaturation degree of 0.07 or less is used as the polyol. Provided is a method for producing a polyurethane foam, characterized in that a mixture with a polyfunctional compound having a low molecular weight isocyanate-reactive group is used, and a mixture of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate is used as the polyisocyanate. It is something.

The polyoxyalkylene polyol used in the present invention is generally obtained by using diethyl zinc, iron chloride, metal porphyrin, double metal cyanide complex, etc. as a catalyst other than an alkali catalyst. In particular, in the present invention, in which a good polyoxyalkylene polyol can be obtained by using a double metal cyanide complex, one or more types of polyoxyalkylene polyols having a low degree of unsaturation and a low hydroxyl value can be used as the polyol. In addition to polyoxyalkylene polyols, polyester polyols,
2 to 8, especially 2 to 8, such as hydroxyl group-containing polydiene polymers
A polyol having four hydroxyl groups can be used in combination. As the polyoxyalkylene polyol, a polyoxyalkylene polyol obtained by adding a cyclic ether, particularly propylene oxide alone or ethylene oxide to a polyhydric alcohol, WE, alkanolamine, polyhydric phenol or other initiator, is preferable.

The hydroxyl value of these high molecular weight polyoxyalkylene polyols or high molecular weight polyol mixtures is 5 to 26.
, it is necessary that the total unsaturation degree is 0.07 or less, and it is particularly preferable that the total unsaturation degree is 0.05 or less. Furthermore, so-called polymer polyols in which fine particles of addition polymers, condensation polymers, etc. are dispersed can also be used as the high molecular weight polyoxyalkylene polyols. This polymer polyol can also be used in combination with the above-mentioned high molecular weight polyols. As the polymer polyol, a polyether polyol containing 3 to 40% by weight of fine particles of acrylonitrile or styrene alone or a copolymer is preferred.The hydroxyl value of this polymer polyol or a mixture of it and other high molecular weight polyols is also 5 to 26.
, total unsaturation 0.07 or less, preferably unsaturation 0.0
It must be 5 or less.

In addition, the hydroxyl value is rmgKOH/gJ, and the total unsaturation degree is expressed as "milliequivalent 7g".

In these high molecular weight polyols, it is preferable that the hydroxyl groups have a high proportion of primary hydroxyl groups. As such a high molecular weight polyether polyol, a polyoxyalkylene polyol having a block chain of oxyethylene group at the terminal is preferable. The content of the terminal oxyethylene group is preferably 2 to 20% by weight, particularly 5 to 15% by weight, based on the molecular weight of the polyoxyalkylene polyol.

In the present invention, the polyfunctional compound having a low molecular weight isocyanate-reactive group used in combination with the above-mentioned high-molecular-weight polyol is an isocyanate-reactive group having two or more isocyanate-reactive groups such as a hydroxyl group, a primary amino group, or a secondary amine group. A compound having a molecular weight of 600 or less, especially 300 or less is preferable, and the number of functional groups is preferably 4 or more. Further, the oxyethylene group content is 5% by weight or more and 60% by weight or less, preferably 10% by weight or more and 50% by weight.
It is as follows. Such compounds include compounds commonly called crosslinking agents.

Examples of such compounds include polyhydric alcohols,
There are low molecular weight polyether polyols obtained by adding a small amount of alkylene oxide to alkanolamines, polyamines, polyhydric alcohols, alkanolamines, sugars, polyamines, monoamines, polyhydric phenols, etc. Furthermore, low molecular weight polyether polyols can also be used. Preferably, a polyether polyol having a hydroxyl value of 200 or more is used. For example, there are polyether polyols in which propylene oxide is added to pentaerythritol, rylbitol, and sucrose, and the end is capped with ethylene oxide. The amount of such a polyfunctional compound to be used is from 0.2 parts by weight to 10 parts by weight, preferably from 3 parts by weight to 8 parts by weight, based on 100 parts by weight of the high molecular weight polyol.

As the polyisocyanate compound, a mixture of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate is used. The mixing weight ratio of tolylene diisocyanate to polyphenylpolymethylene polyisocyanate is in the range of 97/3 to 50,150, preferably 90.
/10 to 60/40. Tolylene diisocyanate contains 2.4 and 2.6 isomers, and the weight ratio of 2.4 to 2.6 is 951.
5-50150 more preferably 90/10-65/35
is within the range of

As polyphenylpolymethylene polyisocyanate, diaminodiphenylmethane and a mixture of these isomers are obtained by the condensation reaction of aniline and formaldehyde, and a diphenylmethane diisocyanate mixture is obtained by further phosgenation, but this can be used as it is, or pure diphenylmethane can be obtained by distillation etc. It is also possible to use one in which the diisocyanate is partially removed.

Furthermore, a mixture of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate is mixed with a polyhydric alcohol,
It is also possible to use one or a mixture of two or more of prepolymer modified products modified with dicarboxylic acids, etc., urea modified products modified with diamines, alkanolamines, etc., nurate modified products, and carbodiimide modified products. It can also be used in a blend with a mixture of isocyanate/polyphenylpolymethylene polyisocyanate.

When reacting polyols and polyisocyanate compounds, the use of catalysts is usually required.

As the catalyst, a metal compound catalyst such as an organic tin compound or a tertiary amine catalyst such as triethylenediamine is used, which promotes the reaction between an active hydrogen-containing group and an isocyanate group. Further, a polymerization catalyst that causes isocyanate groups to react with each other, such as a carboxylic acid metal salt, is used depending on the purpose.

Furthermore, foam stabilizers are often used to form good foam. Examples of the foam stabilizer include silicone foam stabilizers and fluorine-containing compound foam stabilizers. Other additives that may be optionally used include, for example, fillers, stabilizers, colorants, and flame retardants.

As mentioned above, the foaming agents used in the present invention include aqueous foaming agents, R-11, R-12, R-123, and R-12B.

R-141b, halogenated hydrocarbons such as methylene chloride, butane, hexane, air, nitrogen, etc. are used. The aqueous blowing agent refers to water itself or a compound that generates water when reacting with a hydrated substance.

A low-boiling halogenated hydrocarbon can be used together with an aqueous blowing agent as a blowing agent.

When a water-based blowing agent is used as the blowing agent, a portion of the polyisocyanate compound reacts with water to generate carbon dioxide gas. Therefore, the amount of the polyisocyanate compound to be used is based on the sum of the high molecular weight polyol and the low molecular weight polyfunctional compound plus the aqueous blowing agent, and is 0.8 to 1.0% per equivalent of the total amount. Preferably, 3 equivalents are used. 100 of the number of equivalents of this polyisocyanate compound
The ratio is usually called the (isocyanate) index. Therefore, the index of the polyisocyanate compound is preferably 80 to 130. This will be explained in detail below using examples, but it goes without saying that the index is not limited to this.

[Example] Foaming in the present invention was evaluated using the following polyols and polyisocyanates.

Polyol C: A hydroxyl value with an oxyethylene group content of 15% by weight of the total obtained by reacting glycerin with propylene oxide in the presence of a zinc hexacyanocopaltate catalyst and further reacting with ethylene oxide in the presence of an alkali catalyst. 24, polyoxyalkylene polyol with a degree of unsaturation of 0.020.

Polyol C: A hydroxyl value with an oxyethylene group content of 12% by weight of the total obtained by reacting glycerin with propylene oxide in the presence of a zinc hexacyanocopaltate catalyst and further reacting with ethylene oxide in the presence of an alkali catalyst. 17. Polyoxyalkylene polyol with unsaturation degree of 0.023.

Polyol C: A hydroxyl value with an oxyethylene group content of 12% by weight of the total obtained by reacting glycerin with propylene oxide in the presence of a zinc hexacyanocopaltate catalyst and further reacting with ethylene oxide in the presence of an alkali catalyst. 11. Polyoxyalkylene polyol with a degree of unsaturation of 0.026.

Polyol D: Propylene oxide in the presence of a zinc hexacyanocopaltate catalyst is added to pentaerythritol, and ethylene oxide is further reacted in the presence of an alkali catalyst.The oxyethylene group content is 10% by weight of the total. A polyoxyalkylene polyol with a hydroxyl value of 1O1 and a degree of unsaturation of 0.025.

Polyol C: A polyol having a hydroxyl value of 28 and an unsaturated phase of 0.10, with an oxyethylene group content of 15% by weight of the total, obtained by adding propylene oxide to glycerin in the presence of an alkali catalyst and further reacting with ethylene oxide. Oxyalkylene boriol.

Polyold: A polyether-based polyfunctional compound having a hydroxyl value of 450 and containing 28% by weight of oxyethylene groups, obtained by adding propylene oxide to sorbitol in the presence of an alkali catalyst and further reacting with ethylene oxide.

Polyol G: A polyether-based polyfunctional compound containing no oxyethylene group and having a hydroxyl value of 450, obtained by adding propylene oxide to sorbitol in the presence of an alkali catalyst.

Isocyanate H Nitrilene diisocyanate T-80
(manufactured by Nippon Polyurethane Co., Ltd.) and polyphenylpolymethylene polyisocyanate MR-200 (manufactured by Nippon Polyurethane Co., Ltd.) in a weight ratio of 80/20.

Isocyanate I = Tolylene diisocyanate T-80
Alone.

Isocyanate J Nitrilene diisocyanate T-80
A blend of polyphenyl polymethylene polyisocyanate MR-2 at a weight ratio of 407GO.

(Example 1) 70 parts of polyol C (same parts by weight as below), 130 parts of polymer polyol C (containing 20% by weight of acrylonitrile addition polymer based on polyol A), 15.0 parts of polyol, 3.0 parts of water , Dabco33LV O,
7 parts, silicone foam stabilizer 5RX274C (To L/C'
J:] -:/ manufactured by) 1.0 part, isocyanate Hf
After stirring Index1051, 350mm opening x 100mm
The air permeability (air flow) of the resulting foam was poured into a mold (mold temperature: 60°C) and cured for 5 minutes at room temperature.
, the apparent density (core), 25% ILD, impact resilience, elongation, thermal compression set, resonance frequency that indicates ride comfort as a seat cushion, and 6Hz transmission rate.

(Example 2) Polyol B7 (1 part, polymer polyol 8-130
The same procedure as in Example 1 was carried out except that 20% by weight of an acrylonitrile addition polymer was used based on polyol B. The physical properties of the resulting foam are shown in the table.

(Example 3) All examples were as in Example 1 except that 70 parts of polyol C and 130 parts of polymer polyol C (containing 20% by weight of acrylonitrile addition polymer based on polyol C) were used.
I did the same thing.

(Example 4) Everything was the same as Example 1 except that 70 parts of polyol C and 130 parts of polymer polyol C (containing 20% by weight of acrylonitrile addition polymer based on polyol D) were used.
I did the same thing. The physical properties of the resulting foam are shown in the table.

(Example 5) The same procedure as in Example 3 was carried out except that 18.0 parts of polyol was used. The physical properties of the resulting foam are shown in the table.

(Example 6) The same procedure as in Example 2 was carried out except that 70 parts of polyol C was used. The physical properties of the resulting foam are shown in the table.

(Example 7) Everything was carried out in the same manner as in Example 1 except that 70 parts of polyol C and 130 parts of polymer polyol C (containing 20% by weight of an addition copolymer of acrylonitrile/styrene = 515 based on polyol C) were used. . The physical properties of the resulting foam are shown in the table.

(Comparative Example 1) The same procedure as in Example 2 was carried out except that polyol F was not used. The physical properties of the resulting foam are shown in the table.

(Comparative Example 2) All the same as Example 3 except that 5.0 parts of polyol G was used.
I did the same thing. The physical properties of the resulting foam are shown in the table.

(Comparative Example 3) 70 parts of polyol E, polymer polyol E-130
The same procedure as in Example 1 was carried out except that 20% by weight of an acrylonitrile addition polymer based on polyol E was used. The physical properties of the resulting foam are shown in the table.

(Comparative Example 4) The same procedure as in Example 1 was carried out except that Isocyanate I was used. The physical properties of the resulting foam are shown in the table.

(Comparative Example 5) The same procedure as in Example 1 was carried out except that Isocyanate J was used. The physical properties of the resulting foam are shown in the table.

- From Example 2 and Comparative Example 1, it can be seen that the addition of a polyfunctional compound having a low molecular weight isocyanate-reactive group within the claimed range greatly improves impact resilience, air permeability, thermal compression set, etc.

- From Example 3 and Comparative Example 2, the oxyethylene group content is 5.
It can be seen that when the amount is less than % by weight, impact resilience, air permeability, thermal compression set property, etc. are greatly reduced.

- From Example 1 and Comparative Examples 3 to 5, it can be seen that a combination of polyoxyalkylene polyol and polyisocyanate outside the claimed range does not sufficiently exhibit impact resilience, thermal compression set, and riding comfort as a seat cushion.

[Effect of the Invention J The present invention has excellent effects such as high impact resilience, good heat compression set property, and excellent ride comfort as a seat cushion. It is also observed that as the amount of the compound added increases, the above-mentioned physical properties improve.

Claims (1)

[Claims] 1. A method for producing polyurethane elastic foam by reacting a polyol and a polyisocyanate compound in the presence of a blowing agent, a foam stabilizer, a catalyst and other auxiliaries, wherein the polyol has a hydroxyl value of 5 to 26; Using a mixture of a high molecular weight polyoxyalkylene polyol with a total degree of unsaturation of 0.07 or less and a polyfunctional compound having a low molecular weight isocyanate-reactive group, the polyisocyanate is a mixture of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate. A method for producing a polyurethane foam, characterized by using. 2. The method for producing a polyurethane foam according to claim 1, wherein the polyfunctional compound having a low molecular weight isocyanate-reactive group has an oxyethylene group content of 5 to 60% by weight. 3. Claim 1 in which the number of functional groups of the polyfunctional compound having a low molecular weight isocyanate-reactive group is 4 or more
A method for producing a polyurethane foam as described in 2. 4. The molecular weight of the polyfunctional compound having low molecular weight isocyanate-reactive groups is 60 per isocyanate-reactive group.
The method for producing a polyurethane foam according to claim 1, wherein the polyurethane foam is 0 or less. 5. Mixing weight ratio of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate: 97/3 to 50/
50. The method for producing a polyurethane foam according to claim 1, wherein