JPS6159325B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a foam, and more particularly to a method for producing a foam with excellent properties such as mechanical strength and water resistance. It has been well known that polyurethane foams can be obtained by reacting polyols and polyisocyanates in the presence of blowing agents. However, polyurethane foams are generally inferior in hydrolysis resistance, resistance to moist heat deterioration, dimensional stability, etc. Therefore, attempts have been made to improve water resistance by using a diene polymer containing active hydrogen groups as a polyol component, but polyurethane foams obtained using this diene polymer do not have sufficient curability. Not only was the surface sticky, but the strength was also unsatisfactory. Therefore, it has been proposed that these active hydrogen group-containing diene polymers be used as modifiers for polyurethane foams using polyester polyols and polyether polyols (Tokukai No. 56-2314, No. 57-1999).
2321 etc.). However, even in this case, the diene polymer has poor compatibility with polyols, has a small effect on improving impact resistance, and has the drawback that its amount is also limited. The purpose of the present invention is to eliminate the above-mentioned drawbacks,
It is an object of the present invention to provide a method for producing a polyurethane foam from a hydroxyl group-containing polybutadiene and a polyisocyanate, which has sufficient mechanical strength and has good compatibility even when used in combination with other polyols. The present invention has a number average molecular weight of 300 to 30000,
This is a method for producing a foam, characterized by reacting a hydroxyl group-containing liquid polybutadiene having a hydroxyl group content of 1.3 to 7.0 meq/g or an average number of functional groups per molecule of 2.5 to 5.0 with a polyisocyanate in the presence of a blowing agent. The hydroxyl group-containing liquid polybutadiene used in the present invention can be produced, for example, by reacting 1,3-butadiene with hydrogen peroxide in an amount of 10% or more by weight of the butadiene monomer in a liquid reaction medium. In the production of the hydroxyl group-containing liquid polybutadiene, the above-mentioned 1,3-butadiene is basically used, but if necessary, a part of this 1,3-butadiene can be replaced with an ethylenically unsaturated monomer. Several 2 to 22 α-olefinic addition polymerizable monomers are used. Specifically, styrene, α-methylstyrene, vinyltoluene, methyl methacrylate, acrylic acid, vinyl chloride,
Examples include vinylidene chloride, acrylonitrile, acrylamide, 2-ethylhexyl acrylate, n-octadecyl acrylate, maleic anhydride, budene, and 2-hydroxyethyl methacrylate. This monoolefinically unsaturated monomer can be used in combination with 1,3-butadiene, preferably in the range from 0 to 75% by weight. Next, as the liquid reaction medium for carrying out the polymerization reaction of 1,3-butadiene, a solvent having good compatibility with both the 1,3-butadiene and hydrogen peroxide is preferred. Such solvents include isopropanol, ethanol, propyl ether, tetrahydrofuran, ethyl acetate, cellosolve, cellosolve acetate, ethyl cellosolve, N,N-dimethylformamide, acetone, methanol, n-
Examples include propanol and mixtures thereof. The amount of solvent used is 5 to 90% by weight, preferably 30 to 70% by weight of the total charge (monomer, hydrogen peroxide and solvent). Additionally, hydrogen peroxide, which acts as a catalyst, usually
It is used as a 30-80% aqueous solution, and in any case it is necessary to have at least 10% by weight of 1,3-butadiene as hydrogen peroxide, usually 10-80% by weight. Here, if hydrogen peroxide is less than 10% by weight,
Liquid polybutadiene containing hydroxyl groups of 1.3 meq/g or more cannot be obtained. Moreover, if it exceeds 80% by weight, the generation of reaction heat becomes large, making it difficult to control the polymerization reaction, and moreover, it causes discoloration of the resulting polymer, which is undesirable. The polymerization reaction of 1,3-butadiene is carried out at a temperature of 50 to 200°C, preferably 100 to 150°C. The pressure is usually 5 to 100 atm, preferably 10 to 50 atm. The reaction time is usually 10 minutes to 24 hours or longer, preferably 30 to 5 hours. In this way, a liquid polybutadiene containing hydroxyl groups is obtained, which has a number average molecular weight of 300 to 30,000,
The hydroxyl group content is 1.3 to 7.0meq/g. In addition,
The fine structure of this hydroxyl group-containing liquid polybutadiene is 10 to 30% cis-1,4 and 40% trans-1,4.
~70% and vinyl-1,2: 10-35%. If the number average molecular weight of the hydroxyl group-containing liquid polybutadiene used in the present invention is less than 300, the properties as a diene polymer will be lost, and if it exceeds 30,000, the viscosity will increase, which is not preferable. Next, if the hydroxyl group content is less than 1.3meq/g, the physical properties of the reaction cured product with the polyisocyanate compound will not be sufficient, and if it exceeds 7.0meq/g, the viscosity will be relatively high and workability will decrease. , undesirable. on the other hand,
When specifying the average number of functional groups per minute, the number needs to be in the range of 2.5 to 5.0 for the same reason. In the present invention, other active hydrogen group-containing compounds can be used as necessary, and examples of the active hydrogen group-containing compounds used in that case include ethylene glycol, propylene glycol, 1,4-
Low molecular weight polyols such as butanediol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, ethylenediamine, 4,4'-methylene-bis-2-chloroaniline, 4,4'-methylene-bis Examples include polyether polyols such as a propylene oxide adduct of bisphenol A obtained by addition polymerizing an amine compound such as -2-ethylaniline, or a low-molecular polyol or an amine compound with an alkylene oxide such as ethylene oxide or propylene oxide. Furthermore, it is a condensation polymer of polyhydric alcohols such as ethylene glycol, propylene glycol, and 1,4-butanediol and polybasic acids such as phthalic acid, maleic acid, malonic acid, succinic acid, adipic acid, and terephthalic acid. Polyester polyols, acrylic polyols, castor oil, tall oil, etc., each having a hydroxyl group can also be mentioned. Examples of polyisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, liquid modified products of diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, cyclohexanephenylene diisocyanate, chlorophenylene diisocyanate, naphthalene-1,5 -diisocyanate, xylylene-2,2'-diisocyanate, isopropylbenzene-2,4-diisocyanate, polymethylene polyphenyl isocyanate, triphenylmethane triisocyanate, tris(4-phenyl isocyanate thiophosphate, ,3,3', 4,4'-diphenylmethane tetraisocyanate, an addition reaction product of polypropylene glycol or triol and tolylene diisocyanate, an addition reaction product of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate, the above diene polymer and polyisocyanate Examples include prepolymers such as
The blending ratio of this polyisocyanate and the above hydroxyl group-containing liquid polybutadiene is in the range of 0.7 to 2.0, preferably in the range of 0.8 to 1.5, in terms of the equivalent ratio of NCO groups to hydroxyl groups (NCO/OH), and is determined as appropriate depending on the application. do it. Further, the blowing agent used in the present invention includes water and a low boiling point inert solvent such as trichloromonofluoromethane, dichlorodifluoromethane, methylene chloride, and difluorotetrachloroethane. In addition, substances that generate gas when heated, such as azobisisobutylnitrile and azodicarboxylic acid ester, can also be used. In addition to the above-mentioned components, auxiliary components can be added as appropriate in the present invention. For example, bituminous substances, fillers (carbon black,
white carbon, calcium carbonate, vulcanized rubber powder, etc.), catalysts (di-n-butyltin dilaurate, diethylamine, triethylamine, triethylenediamine, ferric chloride, stannous chloride, cobalt naphthenate, etc.), foam stabilizers (alkylene oxide-modified dimethylpolysiloxane, glycerin, etc.), plasticizers (dioctyl phthalate, dibutyl phthalate, etc.), etc. In the method of the present invention, the above-mentioned components may be blended and reacted, and the reaction conditions are not particularly limited. preferable. The foam obtained by the method of the present invention has a density of
It is 0.03 to 0.8 g/cm ³ , preferably 0.05 to 0.5 g/cm ³ , and has excellent mechanical strength, curability, and dimensional stability. It also has excellent temperature sensitivity (especially low-temperature properties) and water resistance. Further, foams having various properties can be obtained by appropriately selecting the content of the hydroxyl group-containing liquid polybutadiene in consideration of the intended use of the foam. Since the foam obtained by the method of the present invention has the above-mentioned excellent properties, it is extremely useful as a shock absorber, a heat insulator, etc. Next, the present invention will be explained in detail with reference to examples. Examples 1 to 5 and Comparative Examples 1 to 5 Various hydroxyl group-containing liquid polybutadienes or polyols shown in Table 1, water as a blowing agent (each part by weight), 0.1 part by weight of triethylenediamine, and polymethylene polyphenyl isocyanate (NCO content 31.5% by weight) was added so that NCO/OH was 1.05, and the mixture was stirred vigorously to react and obtain a foam. The properties of the foam are shown in Table 1. In addition, polyoxypropylene diol (number average molecular weight 1000 or
3000) in the same manner, but the shrinkage was so large that it was impossible to measure the physical properties.

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Claims (1)

[Scope of Claims] 1. Hydroxyl group-containing liquid polybutadiene having a number average molecular weight of 300 to 30,000 and a hydroxyl group content of 1.3 to 7.0 meq/g or an average number of functional groups per molecule of 2.5 to 5.0 is polypropylene in the presence of a blowing agent. A method for producing a foam, which comprises reacting with an isocyanate. 2. The manufacturing method according to claim 1, wherein the hydroxyl group-containing liquid polybutadiene has a hydroxyl group content of 1.5 to 6.0 meq/g or an average number of functional groups per molecule of 2.7 to 4.5.