JPH0948834A - Method for producing flexible polyurethane foam - Google Patents

Abstract

(57) [Abstract] [Problem] Moldability is good even when water alone is used as a foaming agent,
In addition, we manufacture low-density, low-hardness flexible polyurethane foam with excellent foam properties. As a polyol, a polyol (a1) having 3 functional groups, a number average molecular weight of 2400 to 4000 and a terminal primary hydroxyl group conversion rate of 70 to 80%, and a functional group number of 3 and a hydroxyl value of 100 to 130. , HLB is 9.0-1
3.0 and a polyol (a2) having a secondary terminal hydroxyl group, and the weight ratio of (a1) :( a2) is (90: 1).
The polyol used is 0) to (60:40).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing flexible polyurethane foam. More specifically, it relates to a method for producing a low-density, low-hardness flexible polyurethane foam which is excellent in moldability, compression set and the like even in a water-only foaming agent.

[0002]

2. Description of the Related Art Among flexible polyurethane foams, trichlorofluoromethane (R-11) has been conventionally used as a blowing agent in the production of low-density, low-hardness foams used for automobile seat backs and the like. Has been used. However, since R-11 can no longer be used due to the regulation of use due to the problem of ozone layer depletion, a method of foaming only with carbon dioxide generated by the reaction of water and isocyanate is being studied.

[0003]

However, in this method, the carbon dioxide generation efficiency is poor, and it is necessary to use a large amount of water in order to obtain a low-density foam. Therefore, there is a drawback that the foam obtained has poor moldability and the foam physical properties (particularly compression set) deteriorate. Also,
As a method of improving the generation efficiency of carbon dioxide, the mold temperature at the time of injecting the urethane stock solution into the mold is set to the conventional mold temperature of 30 to 45.
A method for obtaining a flexible urethane foam having a low density and a low hardness by increasing the temperature from 50 ° C. to 50 to 70 ° C. has been studied, but the problem of poor moldability has not yet been solved.

[0004]

Means for Solving the Problems As a result of diligent studies on a method for producing a flexible polyurethane foam which solves these problems, the present inventors have found that in the foaming with water alone, a specific polyol is used and the isocyanate index is increased. It has been found that a soft polyurethane foam having a low density and a low hardness, which has good moldability and physical properties suitable for a backing of an automobile seat, can be obtained by controlling the content within a specific range, and has reached the present invention. .

That is, according to the present invention, the polyol (A) and the organic polyisocyanate (B) are reacted in the presence of a foaming agent, a catalyst and a foam stabilizer to produce a flexible polyurethane foam. A polyol (a1) having 3 functional groups, a number average molecular weight of 2400 to 4000, and a terminal primary hydroxyl group conversion ratio of 70 to 80%; and a functional group number of 3, a hydroxyl value of 100 to 130, and an HLB of 9.
0 to 13.0, a polyol having a secondary terminal hydroxyl group (a
2) and the weight ratio of (a1) :( a2) is (9
0:10) to (60:40) is used,
A method for producing a flexible polyurethane foam, wherein the blowing agent is water alone and the isocyanate index is 80 to 95.

Examples of (a1) constituting the polyol (A) in the present invention include alcohols, amines, and alkylene oxide adducts such as ammonia. Examples of alcohols include trihydric alcohols (glycerin, trimethylolpropane, etc.). Examples of amines include trivalent amines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, etc.). As the alkylene oxide, ethylene oxide (hereinafter abbreviated as EO),
Propylene oxide (hereinafter abbreviated as PO), 1,2-,
1,4- and 2,3-butylene oxide and a combination of two or more thereof. Among these, PO and EO are preferable, and the addition format when they are used in combination may be either block or random.

Of the compounds exemplified as (a1), preferred are PO / EO co-adducts of trihydric alcohols, which are of the block addition type in which EO is added to the terminal.

The number of functional groups in (a1) is preferably 3, and when it is less than 3, curing becomes insufficient, the skin on the surface of the urethane foam becomes weak, and the skin adheres to the mold to deteriorate productivity. On the other hand, when it exceeds 3, air permeability of the foam is deteriorated and physical properties of the foam (particularly impact resilience and compression set) are deteriorated. In addition, a desired molded product having a low hardness cannot be obtained.

The number average molecular weight of the (a1) is usually 240
It is 0 to 4000, preferably 2400 to 3500.
When the number average molecular weight is less than 2400, the air permeability is deteriorated and the foam tends to be foamed and the molded product tends to shrink. When it exceeds 4000, the carbon dioxide generation efficiency is deteriorated and a low density foam cannot be obtained. Further, the skin strength at a low isocyanate index becomes weak, and the skin adheres to the mold at the time of demolding, which deteriorates the productivity.

The terminal primary hydroxyl group conversion ratio of (a1) is usually 70 to 80%, preferably 72 to 76%. Terminal 1
If the degree of conversion to primary hydroxyl groups is less than 70%, the skin strength at a low isocyanate index becomes weak and the skin adheres to the mold during demolding. On the other hand, when it exceeds 80%, the air permeability is deteriorated and the foam becomes a closed cell and the molded product shrinks. Here end 1
The primary hydroxylation rate is the ratio of the number of primary hydroxyl groups at the terminal to the total number of hydroxyl groups in (a1), and can be measured by ¹ H nuclear magnetic resonance spectroscopy.

The other component constituting the component (A) in the present invention is a polyol (a2) having a secondary terminal hydroxyl group, such as alcohols, amines and ammonia having three active hydrogens in the molecule. Examples include alkylene oxide adducts. Examples of alcohols include trihydric alcohols (glycerin, trimethylolpropane, etc.). Examples of amines include trivalent amines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, etc.). As alkylene oxide, EO, PO, 1,2-, 1,
4- and 2,3-butylene oxide and their 2
Combinations of two or more species are included. Among these, PO and EO are preferable, and when they are used in combination, the addition form other than the molecular end may be either block or random.

Of the compounds exemplified as (a2), preferred are alkylene oxide adducts of trihydric alcohols, and the addition form is EO after addition of PO.
Is an addition polymerization method, or is a method in which EO and PO are previously mixed and co-added, and then PO is further added.

The number of functional groups in (a2) is preferably 3. If the number of functional groups is less than 3, the cure will be insufficient and the moldability of the urethane foam will be deteriorated. On the other hand, when it exceeds 3, the air permeability of the foam deteriorates and the physical properties of the foam deteriorate.
Furthermore, shrinkage etc. occurs in the molded product.

The hydroxyl value of the (a2) is usually 100 to 13.
It is 0, preferably 105-115. Hydroxyl value is 10
If it is less than 0, the efficiency of carbon dioxide generation becomes poor, and the desired low-density and low-hardness foam cannot be obtained. If it exceeds 130, the foam becomes a closed cell and the molded product shrinks.

The HLB of (a2) is usually 9.0-1.
It is 3.0, preferably 9.0 to 11.0. If the HLB is less than 9.0, the carbon dioxide generation efficiency will be poor, and the desired low-density / low-hardness foam cannot be obtained.
If it exceeds 0, foaming becomes unstable and cracks occur in the molded product.

Here, HLB (HYDROPHILE-
LIPOPHILE BALANCE) is a numerical value calculated by the method of Oda et al. [Source: Oda, Teramura “Synthesis of Surfactants and Their Applications”, page 501, published by Maki Shoten (1957)]. HLB is used as a numerical value indicating hydrophilicity, and is represented by a numerical value in the range of 0 to 40. The larger the numerical value, the higher the hydrophilicity.

The polyol (A) in the present invention comprises a mixture of the above-mentioned (a1) and (a2), and (a1):
The weight ratio of (a2) is usually (90:10) to (60: 4).
0), preferably (85:15) to (70:30). If the ratio of (a2) is less than 10, the efficiency of carbon dioxide generation is poor, and the desired foam with low density and low hardness cannot be obtained. If it exceeds 40, the foam collapses.

The foaming catalyst used in the present invention is a known catalyst usually used in polyurethane, for example, a metal salt of carboxylic acid (sodium acetate, lead octylate,
Zinc octylate, cobalt naphthenate, stannas octoate, etc.); alkali metal or alkaline earth metal alkoxides or phenoxides (sodium methoxide, sodium phenoxide, etc.); tertiary amines (triethylamine, triethylenediamine, N-methylmorpholine) , Dimethylaminomethylphenol, pyridine, etc.); quaternary ammonium salts (tetraethylhydroxylammonium, etc.); and organometallic compounds containing metals such as tin and antimony (tetraphenyltin, tributylantimony oxide, etc.) and the like. Among these, preferred are metal salts or organometallic compounds of carboxylic acids containing tertiary amines, tin or antimony, and combinations of two or more thereof.

As the organic polyisocyanate (B),
Known polyurethanes commonly used in polyurethanes, for example, aromatic polyisocyanates having 6 to 20 carbon atoms (excluding the carbon number in the NCO group) [2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI , 2,4'- or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI, polyaryl polyisocyanate (PAPI), etc.]; Aliphatic isocyanate having 2 to 18 carbon atoms (hexamethylene diisocyanate, lysine diisocyanate, etc.); Alicyclic polyisocyanates having 4 to 15 carbon atoms (isophorone diisocyanate, dicyclohexyl diisocyanate, etc.); modified products of these polyisocyanates (urethane group, carbodiimide group, allophanate group, urea group, uretdione group, buret group, uretonimine , Isocyanurate group, oxazolidone group-containing modified products, etc.); Japanese Patent Application No. Sho 59-199160
Polyisocyanates other than those described above in the specification of Japanese Patent Publication;
And a combination of two or more of these.

Among the examples exemplified as (B) above, preferred are TDI alone and a mixture of TDI and modified MDI and / or crude MDI having a TDI content of 70% by weight or more, and particularly preferred. TDI
Alone.

The isocyanate index for foaming by reacting (A) and (B) [equivalent of isocyanate to 1 equivalent of active hydrogen of polyol component × 100] is
It is usually 80 to 95, preferably 85 to 95. When the isocyanate index is less than 80, the skin of the foam becomes weak, the skin is likely to adhere to the mold at the time of demolding, and the carbon dioxide generation efficiency is deteriorated, so that a low-density foam cannot be obtained. On the other hand, when the isocyanate index exceeds 95, the foam becomes hard and the desired low-hardness foam cannot be obtained.

As the foam stabilizer, those usually used for polyurethane are used, and specific examples thereof include "SZ-1142", "L-520" and "L" manufactured by Nippon Unicar Co., Ltd.
-540 "," SZ-1105 "," L-5740M "
And "L-5740S";"SH-190","SH-193" and "SRX-" manufactured by Toray Silicon Co., Ltd.
294A "; and the like.

The amounts of the foaming agent and foam stabilizer used in the present invention are as follows. The foaming agent is preferably water alone, and is usually 2.5 to 8 parts by weight, preferably 3 to 6 parts by weight, based on 100 parts by weight of the polyol (A). If necessary, a CFC compound or a halogenated hydrocarbon compound may be used in combination. The foam stabilizer is usually 0.5 to 5.0 parts by weight, preferably 0.8 to 3.
0 parts by weight.

The production method of the flexible polyurethane foam for automobile seats using the method of the present invention may be any conventionally known method such as a hot cure method or a cold cure method, but a hot cure method is preferable. is there.

[0025]

Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited thereto. In addition, the numerical value of the foaming prescription column in an Example and a comparative example shows a weight part.

[0026]

【Example】

Examples 1 to 10 and Comparative Examples 1 to 7 Polyurethane foam was foamed in a mold according to the foaming formulation shown in Table 1, Table 2 and Table 3, taken out of the mold and left for one day and night, and then cut into each polyurethane foam. do it,
Its physical properties were measured. The results are shown in Tables 1, 2 and 3.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

(Explanation of symbols of raw materials used) Polyol (A) (a1): PO-EO adduct of glycerin, EO terminal content 20% by weight, primary primary hydroxyl group conversion rate = 74%, hydroxyl value = 56 (a2): glycerin EO, PO block adduct,
EO content 33% by weight, hydroxyl value = 112, HLB =
10.2 Other polyols (a3) [of (A) (a
Other than 1) and (a2)] (a3-1): PO adduct of glycerin, hydroxyl value = 1
12, HLB = 5.2 (a3-2): PO-EO co-adduct of glycerin, EO
End content of 12% by weight, primary primary hydroxyl group conversion rate = 61
%, Hydroxyl value = 56 ・ Organic polyisocyanate (B) "Coronate T-80" manufactured by Nippon Polyurethane Industry Co., Ltd.
(TDI, NCO% = 48.3) is used.-Catalyst-1: Activator Chemical Co., Ltd. "Minicol L-1.
020 "(33% dipropylene glycol solution of triethylenediamine) -Catalyst-2: NEM (N-ethylmorpholine) manufactured by Nippon Emulsifier Co., Ltd.-Catalyst-3:" Neostan U-28 "manufactured by Nitto Kasei Co., Ltd.
(Stannas dioctoate) -Foam stabilizer "SZ-1142" (dimethyl siloxane-based foam stabilizer) manufactured by Nippon Unicar Co., Ltd.

(Foaming conditions) Mold shape: 300 mm × 300 mm × 100 mm Material: Aluminum Mold temperature: 33-45 ° C. Mixing method: Hand mixing Rotation speed of stirring blade: 5000 rpm / min Raw material temperature: 25 ± 1 ° C.

(Explanation of symbols in physical properties column in Tables 1 and 2) The measuring method and unit of foam physical properties are shown below. Core density: According to JIS K6401, the unit is kg
/ M ³ foam hardness: JIS K6401, conforming to kg
f / 314 cm ² Repulsion elastic modulus: conforming to JIS K6401, unit:% Compression set: conforming to JIS K6401, unit:% -Moldability was judged by observing a molded article of polyurethane foam.

[0033]

EFFECT OF THE INVENTION By using the method of the present invention, the foaming efficiency of urethane foam is improved, and a foam of low density and low hardness can be obtained without using a large amount of water as a foaming agent.
Is obtained. Therefore, as compared with the conventional foam manufacturing method using water alone as a foaming agent, a foam having the same density can be obtained with a small amount of water used, so that the compression set can be improved and it is suitable for a back seat of an automobile sheet. Also, a low-density, low-hardness flexible polyurethane foam can be obtained.

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[Procedure amendment]

[Submission date] June 12, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

Examples of (a1) constituting the polyol (A) in the present invention include alcohols, amines, and alkylene oxide adducts such as ammonia. Examples of alcohols include trihydric alcohols (glycerin, trimethylolpropane, etc.). Examples of amines include alkanolamines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, etc.). Examples of the alkylene oxide include ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), 1,
2-, 1,4- and 2,3-butylene oxide and combinations of two or more of these are included. Among these, PO and EO are preferable, and the addition format when they are used in combination may be either block or random.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

The other component constituting the component (A) in the present invention is a polyol (a2) having a secondary terminal hydroxyl group, such as alcohols, amines and ammonia having three active hydrogens in the molecule. Examples include alkylene oxide adducts. Examples of alcohols include trihydric alcohols (glycerin, trimethylolpropane, etc.). Examples of amines include alkanolamines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, etc.). As alkylene oxide, EO, PO, 1,
2-, 1,4- and 2,3-butylene oxide and combinations of two or more of these are included. Among these, PO and EO are preferable, and when they are used in combination, the addition form other than the molecular end may be either block or random.

Claims (1)

[Claims] 1. A method for producing a flexible polyurethane foam by reacting a polyol (A) and an organic polyisocyanate (B) in the presence of a foaming agent, a catalyst and a foam stabilizer, wherein (A) has a functional group number of 3, the number average molecular weight is 2400 to 4000, and the terminal primary hydroxyl group conversion rate is 70 to 80.
% Of the polyol (a1), the number of functional groups is 3, the hydroxyl value is 100 to 130, the HLB is 9.0 to 13.0, and the terminal hydroxyl group is secondary polyol (a2).
The weight ratio of (a1) :( a2) is (90:10) to (6).
0:40), the blowing agent is water alone, and the isocyanate index is 80 to 95.
And a method for producing a flexible polyurethane foam.