JPH0131536B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing soft, highly elastic polyurethane foams. In recent years, the automobile industry has been calling for lighter vehicle bodies in order to save on fuel consumption, and even in the polyurethane foam used in automobile cushioning materials, efforts have been made to lower the specific gravity of the foam itself and to reduce the feeling of the foam itself bottoming out. In order to eliminate this problem, polyurethane foams with improved hardness, load coefficient (SAG coefficient), impact resilience, etc., are required, especially polyurethane foams with low specific gravity and high elasticity and high hardness. Polyurethane foam, which is currently used in automobile cushioning materials, suffers from poor wet set (moist heat distortion) when the specific gravity of the foam itself is lowered.
Increasing the hardness also deteriorates the feel of the foam, resulting in a stiff state, and in addition, scorch tends to enter and the wet set properties of the foam deteriorate, which poses practical problems. Therefore, the polyurethane foam currently used for automobile cushioning materials is produced with a high specific gravity of 50 kg/m3 or ^more , which is a major disadvantage in terms of cost and is This goes against efforts to reduce the weight of vehicle bodies. As a known technique to improve the above-mentioned drawbacks,
No. 53-4039, Special Publication No. 53-4119 and Special Publication No. 54-
No. 4757 is disclosed, but although the wet set is good, other foam physical properties such as hardness and impact resilience are poor, or even if the hardness is satisfied, the wet set is poor.
Also, there are drawbacks such as poor tear strength. The present inventors have conducted intensive research to improve the above-mentioned drawbacks, and as a result, they have come to provide the present invention. That is, in producing a polyurethane foam by reacting a polyhydroxyl compound and an organic polyisocyanate in the presence of a catalyst, water and/or a volatile blowing agent, the polyhydroxyl compound A has a number of hydroxyl groups or an average number of hydroxyl groups of 3 or more. , a polyoxyalkylene polyol (hereinafter referred to as polyoxyalkylene polyol A) in which at least 50% of the terminal hydroxyl groups are primary hydroxyl groups and a hydroxyl value of 20 to 60 mgKOH/g, and B a non-amine polyhydric alcohol with an alkylene oxide. polyoxyalkylene polyol (hereinafter referred to as polyoxyalkylene polyol), which has a number of hydroxyl groups or an average number of hydroxyl groups of 4 or more, ethylene oxide in the alkylene oxide is 5 to 80% by weight, and a hydroxyl value of 100 mgKOH/g or more. A compound selected from dialkanolamines, polyhydroxyalkylated polyamines, or hydroxyalkylated aromatic amines and having one >NH group in the molecule (hereinafter referred to as compound C). A mixture, wherein the mixing ratio (weight) of the polyoxyalkylene polyols A and B is the polyoxyalkylene polyol A:the polyoxyalkylene polyol B=80-98:20-2, and the mixture of the compound C The proportion is 0.5 to 100 parts by weight of the mixture with the polyoxyalkylene polyols A and B.
3 parts by weight of a soft, highly elastic polyurethane foam (hereinafter referred to as polyurethane foam). The polyoxyalkylene polyol A used in the present invention is a polyoxyalkylene polyol obtained by adding an alkylene oxide to a starting material having three or more active hydrogen groups, and
and the number of hydroxyl groups or the average number of hydroxyl groups is 3 or more, preferably 3 to 6, and at least 50% of the terminal hydroxyl groups,
Preferably 60% are primary hydroxyl groups and the hydroxyl value is 20.
~60mgKOH/g, preferably 28-40mgKOH/g
polyoxyalkylene polyols or mixtures thereof. Examples of starting materials having 3 or more active hydrogen groups include glycerin, trimethylolpropane, 1.2.6
Examples include polyalcohols such as hexanetriol, diglycerin, pentaerythritol, sorbitol, and shugar, and amines such as triethanolamine, triisopropanolamine, and ethylenediamine. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide, and one or more of these alkylene oxides can be used. In polyoxyalkylene polyol A,
When the number of hydroxyl groups or the average number of hydroxyl groups is less than 3, the polyurethane foam tends to collapse because the hardness and permanent deformation are poor and the urethane resin formation reaction is slow. If the proportion of primary hydroxyl groups in the terminal hydroxyl groups is less than 50%, the polyurethane foam tends to collapse because the urethane resin formation reaction is slow, and even if the foam can be formed, sufficient hardness cannot be obtained, and the curing property is also poor. It becomes worse and the mold release time has to be extended. If the hydroxyl value exceeds 60mgKOH/g, the closed cell content of the polyurethane foam will increase,
Impact resilience and permanent set deteriorate, making crushing difficult. In addition, if the hydroxyl value is less than 20mgKOH/g,
Although crushing becomes easier, wet set is particularly poor and hardness is also reduced, which is undesirable. In addition, as the polyoxyalkylene polyol A, other polyoxyalkylene polyols having two or more hydroxyl groups, or ethylenically unsaturated monomers such as acrylonitrile, styrene, methyl methacrylate, etc. are graft polymerized or / and polyoxyalkylene polyol A by mixing the dispersed
Examples include those that satisfy the above-mentioned average number of hydroxyl groups, proportion of primary hydroxyl groups in terminal hydroxyl groups, hydroxyl value, etc. Next, polyoxyalkylene polyol B is a polyoxyalkylene polyol obtained by adding an alkylene oxide to a non-amine polyhydric alcohol, and has a hydroxyl group number or an average number of hydroxyl groups of 4 or more, and has ethylene in the alkylene oxide. 5 to 80% by weight of oxide, preferably 20
~60% by weight, hydroxyl value 100mgKOH/g or more,
Preferred examples include polyoxyalkylene polyols or mixtures thereof having an amount of 200 to 500 mg KOH/g. Examples of the non-amine polyhydric alcohol having 4 or more hydroxyl groups include diglycerin, pentaerythritol, sorbitol, and sugar. Examples of the alkylene oxide include those mentioned above. In polyoxyalkylene polyol B,
When the number of hydroxyl groups or the average number of hydroxyl groups is less than 4, desired hardness cannot be obtained. If the ethylene oxide content is less than 5% by weight, wet set will be poor and finger marks will easily form when the foam is released.
If it exceeds 80% by weight, the desired hardness cannot be obtained and the foam surface becomes rough and tends to collapse. Further, if the hydroxyl value is less than 100 mgKOH/g, the desired hardness cannot be obtained. In addition, as polyoxyalkylene polyol B, polyoxyalkylene polyol B is mixed with another polyoxyalkylene polyol having a hydroxyl group number of 2 or more, and polyoxyalkylene polyol B has the above-mentioned average number of hydroxyl groups, ethylene oxide content ratio, hydroxyl value. There are also those that satisfy the following regulations. The mixing ratio (weight) of polyoxyalkylene polyols A and B is polyoxyalkylene polyol A:polyoxyalkylene polyol B
=80-98:20-2, preferably 85-97:15-3. If the mixing ratio (weight) of polyoxyalkylene polyol B exceeds 20, the feel and impact resilience of the foam will deteriorate, making it unsuitable for use as a cushion material. Moreover, when the polyoxypolyalkylene polyol B is less than 2, no effect is observed at all, that is, the hardness is unsatisfactory. Next, as compound C, there is one >NH group in the molecule.
Examples of such compounds include dialkanolamines, polyhydroxyalkylated polyamines, and hydroxyalkylated aromatic amines. Examples of dialkanolamines include diethanolamine and diisopropanolamine, and examples of polyhydroxyalkylated polyamines include, for example, polyhydroxyalkylated polyamines prepared by adding alkylene oxide to various (poly)ethylene polyamines so that one >NH group is present. Examples of the hydroxyalkylated aromatic amines include compounds in which alkylene oxide is added to aniline so that one >NH group is present. The mixing ratio of compound C is 0.5 to 3 parts by weight, preferably 0.5 to 2 parts by weight, per 100 parts by weight of the mixture with polyoxyalkylene polyols A and B. If the amount is less than 0.5 parts by weight, the foam will completely collapse immediately after forming into a foam. Next, examples of the organic polyisocyanate used in the present invention include tolylene diisocyanate, polymethylene polyphenyl isocyanate, and specific examples include TDI-80,
Examples include crude MDI and mixtures thereof. The ratio used is an index of 90-120, preferably 95-108. If the index is less than 90, the hardness and wet set are poor. If it exceeds 120,
Form release becomes difficult. Next, the catalyst used in the present invention, water and/or
Alternatively, volatile blowing agents include known ones used in polyurethane foam production,
Examples of the catalyst include amine catalysts and tin catalysts, and examples of water and/or volatile blowing agents include water and low-boiling organic fluorinated hydrocarbons. In addition, a known foam stabilizer may be used if necessary. The polyurethane foam of the present invention is produced by known methods. In the present invention, the polyurethane foam obtained has the following characteristics. (a) The specific gravity of the foam is light and the hardness is sufficiently satisfactory. (b) It is a highly elastic foam with high rebound resilience and SAG coefficient. (c) The disadvantage of poor wet set seen in high elastic foams can be overcome. (d) It has good curing properties and can be released from the mold at low temperatures and in a short time. (E) Even when combined with graft polyol, scorch does not enter the foam. Therefore, the polyurethane foam obtained in the present invention is most suitable as a polyurethane foam used to reduce the specific gravity of a cushion material for reducing the weight of automobile bodies, and is also most suitable as a cushion material for furniture and the like. In addition, due to its high hardness, it can be used for headrests, armrests, etc. in some cases. Examples of the present invention are described below. In the examples, "parts" are based on weight. Example 1 Various polyoxyalkylene polyols A, polyoxyalkylene polyol B and compound C were produced according to known methods. Each is shown in Tables 1, 2 and 3. B Various polyoxyalkylene polyols A

【table】 B Various polyoxyalkylene polyols B

【table】 C Various compounds C

[Foaming prescription]

Polyoxyalkylene polyol A Variable part Polyoxyalkylene polyol B Variable part Compound C Variable part Water 3.5 parts Dabco 33LV (amine catalyst) 0.5 part Stannous Octoate T-9 (tin catalyst) 0.06 part Silicone oil SF2962 (silicone foam stabilizer) Agent) 0.4 parts TDI-80 (organic polyisocyanate) Index 103 [Molding conditions] Foaming mold dimensions 400 x 400 x 70 (mm) Foaming mold temperature 40 to 55℃ Mold release agent Permold 178 Cure conditions 100 °C, 6 minutes

【table】

【table】

Claims (1)

[Scope of Claims] 1. In producing a flexible polyurethane foam by reacting a polyhydroxyl compound and an organic polyisocyanate in the presence of a catalyst, water and/or a volatile blowing agent, the polyhydroxyl compound has a number of A hydroxyl groups or an average number of hydroxyl groups. The number of hydroxyl groups is 3 or more, and at least 50% of the terminal hydroxyl groups are primary hydroxyl groups,
A polyoxyalkylene polyol with a hydroxyl value of 20 to 60 mgKOH/g (hereinafter referred to as polyoxyalkylene polyol A); B A polyoxyalkylene polyol with an alkylene oxide added to a non-amine polyhydric alcohol, and the number of hydroxyl groups or the average number of hydroxyl groups is 4. In the above, a polyoxyalkylene polyol (hereinafter referred to as polyoxyalkylene polyol B) having an alkylene oxide containing 5 to 80% by weight of ethylene oxide and a hydroxyl value of 100 mgKOH/g or more, C dialkanolamines, polyhydroxyalkyl a compound selected from hydroxyalkylated polyamines or hydroxyalkylated aromatic amines and having one >NH group in the molecule (hereinafter referred to as compound C), which is a mixture with the polyoxyalkylene polyols A and B; The mixing ratio (weight) of the polyoxyalkylene polyol A:the polyoxyalkylene polyol B=80-98:20-2, and the mixing ratio of the compound C is 100% by weight of the mixture with the polyoxyalkylene polyols A and B. 0.5~
3 parts by weight of a soft, highly elastic polyurethane foam.