JPH073062A - Production of non-rigid polyurethane slab foam - Google Patents

Abstract

PURPOSE:To obtain a non-rigid polyurethane slab foam useful for a cushioning material for furniture, having low density, excellent elasticity and physical properties of elongation by using an organic polyisocyanate, an active hydrogen compound, water and a specific additive without using an auxiliary blowing agent. CONSTITUTION:(A) An organic polyisocyanate, (B) an active hydrogen compound, (C) water and (D) a polyoxythylene of both ends hindered type of formula I [R1 and R2 CmH2m+1 (m is natural number); n is natural number], formula II (R3 and R4 are CmH2m+1) or formula III (R5 and R6 are CmH2m+1) are used to obtain the objective foam. In obtaining the foam, the component A is a mixture of diphenylmethane diisocyanate and a polyphenyl polyisocyanate in the blending ratio of 20/80-80-/20. The mixture contains 40-90wt.% of diphenylmethane diisocyanate, diphenylmethane diisocyanater contains 15-60wt.% of 2,2'- and 2,4'-isomer mixture and the component B is preferably a polyether type or a polyester type polyol.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a flexible polyurethane slab foam. More specifically, in the production of a flexible polyurethane slab foam which is used in an extremely large amount for cushion materials for automobiles, furniture, etc., a specific organic polyisocyanate is used, and at least one end-capped polyisocyanate is used as an additive. The present invention relates to a method for water-foaming a flexible polyurethane slab foam which has a low density by using oxyethylene glycols, is rich in elasticity, and is excellent in elongation properties.

[0002]

2. Description of the Related Art Conventionally, as an organic polyisocyanate for producing a flexible polyurethane slab foam,
Tolylene diisocyanate (hereinafter abbreviated as TDI) alone or a mixture of TDI and / or its isocyanate group-terminated prepolymer and polymethylene polyphenyl polyisocyanate has been generally used. However, the improvement of the production work environment has been desired due to the high vapor pressure of TDIs, and therefore improvement has been desired. In recent years, a technique for producing a flexible polyurethane slab foam using only diphenylmethane diisocyanates without using TDI has been developed.
However, the main technique for developing this technique is a technique for molding in a mold, and a technique for producing a flexible polyurethane slab foam by using only diphenylmethane diisocyanates has not been established yet.

In the production of flexible polyurethane foam, water as a carbon dioxide gas generating agent and chlorofluorocarbons are usually used together as an auxiliary foaming agent for reinforcing the foaming action of water. However, with the worldwide criticism of the use of chlorofluorocarbons, investigations have been made to obtain flexible polyurethane foams using water as the substantially sole blowing agent. A drawback of using diphenylmethane diisocyanates alone to obtain a flexible polyurethane foam is that it is difficult to produce a foam having a low density unless an auxiliary foaming agent other than water is used.

[0004]

DISCLOSURE OF THE INVENTION In obtaining a flexible polyurethane slab foam with water as the substantially sole blowing agent, the present inventors have used diphenylmethane diisocyanates alone as an organic polyisocyanate to produce a flexible polyurethane slab foam. As a result of diligent study on a method for obtaining a low-density foam by suppressing the required reduction in physical properties as much as possible, by adopting both end-capped polyoxyethylene glycols as at least one additive in the system, They have found that they have excellent effects and have completed the present invention.

[0005]

Means for Solving the Problems That is, according to the present invention, when a flexible polyurethane slab foam is obtained using an organic polyisocyanate, an active hydrogen compound, a foaming agent and an additive, water is used as a foaming agent, and an organic polyisocyanate is used. Is a diphenylmethane diisocyanate alone, and the end-capped polyoxyethylene glycols are used as at least one additive in the system, which is a method for producing a flexible polyurethane slab foam.

The production of the flexible polyurethane slab foam according to the present invention uses water as a foaming agent, and contains an active hydrogen compound known in the production of the flexible polyurethane foam and polyoxyethylene glycols having both ends blocked as an essential component. And a mixture of diphenylmethane diisocyanate (hereinafter, abbreviated as MDI) and polymethylene polyphenyl polyisocyanate (hereinafter, abbreviated as P-MDI) as an organic polyisocyanate having a weight mixing ratio of 20/80 to 80/20. Wherein the mixture contains MDI in the range of 40-90 weight percent and the MDI contains 2,2'- and 2,4'-isomer mixture in the range of 15-60 weight percent. Contains M
The reaction and foaming are carried out by adding DI in an amount not exceeding 100 as the isocyanate index. The flexible polyurethane slab foam obtained in this manner can have a low density even when diphenylmethane diisocyanates are used alone and an auxiliary foaming agent is not used.

The active hydrogen compound used in the present invention is a polyether polyol and / or a polyester polyol. The polyether polyol includes all those having an average molecular weight in the range of 2000 to 10,000 and an average number of functional groups in the range of 2 to 4. The polyester polyol has an average molecular weight of 1,000 to 9000.
And the average number of functional groups is in the range of 2 to 4. The polyether polyol and the polyester polyol are used individually or in the form of a mixture.

As the foaming agent in the production of flexible polyurethane slab foam, water as a carbon dioxide gas generating agent, chlorofluorocarbons and low boiling point solvents are usually used together as an auxiliary foaming agent for reinforcing the foaming action of water. However, due to the worldwide depletion of chlorofluorocarbons due to the problem of ozone depletion,
In the present invention, water is used as the virtually sole blowing agent. The amount of water used is in the range of 4 to 10 parts by weight with respect to 100 parts by weight of the active hydrogen compound.

As the additives, in addition to the polyoxyethylene glycols having both ends blocked as essential components, the following can be used. For example, a catalyst, a foam stabilizer, and optionally a flame retardant, a viscosity modifier, a pigment and the like can be mentioned. Both end-blocked polyoxyethylene glycols as an essential component of the additive are represented by the following general formulas (I), (II), (II
It is represented by I).

Embedded image R ₁ —O— (CH ₂ CH ₂ O) n—R ₂ (I) and / or And / or (In the formula, n represents an integer of 1 or more, R _{1 to} R ₆ : general formula, C _m H _{2m + 1} , and m represents an integer of 1 or more.)

Examples of the catalyst include tertiary amines such as dimethylethanolamine, triethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine and dimethylcyclohexylamine, and organic tin compounds such as tin octenoate and dibutyltin dilaurate. . Examples of the foam stabilizer include various siloxane polyalkylene oxide block copolymers, and the selection of the type is determined by the compounding recipe. As a flame retardant,
Examples thereof include trischloroethyl phosphate, trischloropropyl phosphate, tricrudyl phosphate, and chlorinated paraffin.

Examples of the viscosity modifier include dibutyl phthalate, dioctyl phthalate and alkylene carbonates. When obtaining flexible polyurethane slab foams, it is very significant that the drawback that tends to occur in a system that uses water alone as a foaming agent has been solved by adopting both end-capped polyoxyethylene glycols as an essential component of the additive. That's right.

[0012]

INDUSTRIAL APPLICABILITY In the production of the flexible polyurethane slab foam of the present invention, a problem that tends to occur in a system in which diphenylmethane diisocyanate is used alone as the organic polyisocyanate and water is used alone as the foaming agent, that is, low density It has become possible to solve the difficulty of polymerization, the reduction of impact resilience, the property of tearing property, the property of elongation and the like by adopting polyoxyethylene glycols with both ends blocked as an essential component of the additive. In a water-foaming system, an increase in the amount of water added for lowering the density leads to an increase in the amount of catalyst added, which not only unnecessarily increases the reactivity but also impairs the foaming balance, and thus the foam. , Which makes it difficult to reduce the density.

In the present invention, the both-end-capped polyoxyethylene glycols adopted as an essential component of the additive suppress the unnecessary internal heat generation of the foam even in a system in which the amount of water added is increased, and the mild reactivity is exhibited. It is thought that it works effectively for holding the foam, and as a result, it has become possible to improve the physical properties of the foam and reduce the density.

[0014]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "weight percent", respectively.

Preparation 1 Preparation of organic polyisocyanate (A) 2,2'- and 2,4'-isomer mixture in 400 parts of MDI containing 2,2'- and 2,4'-isomer mixture 30.2% P-containing 45% MDI containing 12.0%
600 parts of MDI (Coronate 1107, manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content 31.0%) was added and stirred for 30 minutes to obtain an organic polyisocyanate (I) to be subjected to a foaming test. NC of the obtained organic polyisocyanate
O content is 32.0%, isomer content in MDI is 1
It was 5.3%.

Preparation 2 Preparation of organic polyisocyanate (B) 2,2'- and 2,4'-isomer mixture in 500 parts of MDI containing 2,2'- and 2,4'-isomer mixture 52.1% 500 parts of P-MDI (MF-24MR, manufactured by Nippon Polyurethane Industry Co., Ltd., NCO content 31.2%) containing 40.5% MDI containing 9.5% was added, and the mixture was stirred for 30 minutes and subjected to a foaming test. An organic polyisocyanate (II) was obtained. NC of the obtained organic polyisocyanate
O content is 32.3%, isomer content in MDI is 2
It was 8.0%. Hereinafter, comparisons were made under various conditions using the organic polyisocyanates (A) and (B). Table 1 shows foaming conditions, and Table 2 shows foam physical property values.

[0017]

[Table 1]

[0018]

[Table 2]

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Claims (7)

[Claims] 1. When a flexible polyurethane slab foam is obtained using an organic polyisocyanate, an active hydrogen compound, a foaming agent and an additive, water is used as a foaming agent, and at least one of the following general formula (I) is used as an additive. , (II), (II
A method for producing a flexible polyurethane slab foam, which comprises using polyoxyethylene glycols having both ends blocked represented by I). Embedded image R ₁ —O— (CH ₂ CH ₂ O) n—R ₂ (I) (In the formula, n represents an integer of 1 or more, R _{1 to} R ₆ are general formulas, —C _m H _2m +1 and m represents an integer of 1 or more.) 2. The organic polyisocyanate is a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate, and the weight mixing ratio thereof is 20 /.
Within the range of 80-80 / 20, the mixture contains diphenylmethane diisocyanate in the range of 40-90 weight percent, and diphenylmethane diisocyanate comprises the mixture of 2,2'- and 2,4'-isomers of 15-.
The manufacturing method according to claim 1, wherein the content is within the range of 60 weight percent. 3. The method according to claim 1, wherein the active hydrogen compound is a polyether polyol and / or a polyester polyol. 4. The method according to claim 1, wherein water used as a foaming agent is used in an amount of 4 to 10 parts by weight with respect to 100 parts by weight of the active hydrogen compound. 5. A compound represented by the general formula (I), which is an essential component of an additive,
2. The production method according to claim 1, wherein (II) and (III) are used in an amount not exceeding 10 parts by weight with respect to 100 parts by weight of the active hydrogen compound. 6. The process according to claim 1, wherein the composition of the foam-forming reaction mixture does not exceed 100 as an isocyanate index. 7. The method according to claim 1, wherein the foam density does not exceed 30 kg / m ³ .