JPS6028297B2 - Method for producing phenolic resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a phenolic resin foam having uniform, fine expanded particles.

As a method for producing phenolic resin foam, a blowing agent, a curing agent, a surfactant, etc. are mixed with a novolac resin obtained by reacting phenol and formaldehyde in the presence of an acidic catalyst while simply pulverizing it (Japanese Patent Publication No. 1973- 19624) or a method in which a novolac resin is mixed with a blowing agent, a curing agent, a surfactant, etc., and then kneaded and extruded using an extruder (Japanese Patent Publication No. 48-133).

However, the phenolic resin foams obtained by these methods have coarse and non-uniform foamed particles, and it has been difficult to obtain a phenolic resin having uniform and fine foamed particles. In addition, in order to improve performance such as brittleness of foam, there is a method of heating and kneading a vinyl acetal-modified phenol resin obtained by adding polyvinyl alcohol to phenol and reacting it with aldehyde, a blowing agent, and a curing agent (Japanese Patent Publication No. 38-12189). However, this resin has a low melting point and is difficult to crush, and has disadvantages such as poor workability due to solidification of the composition.

The present invention solves the above-mentioned drawbacks and relates to a method for producing a phenolic resin foam having uniform and fine expanded particles and good moldability. After neutralizing the reaction product, the aqueous phase is separated and removed from the resin phase, and a surfactant, polyvinyl alcohol, and an alkali metal or zinc oxide or hydroxide are added to the resin phase, followed by heating and dehydration. Next, a foaming agent and a curing agent are added, kneaded, and then heated to foam and harden. The phenols used in the present invention include phenol, cresol, xylenol, resorcinol, etc., and the aldehydes include formaldehyde, paraformaldehyde, furfural, etc. As the acidic catalyst, inorganic acids such as hydrochloric acid and sulfuric acid, or organic acids such as oxalic acid and benzenesulfonic acid are used. The reaction is carried out under reflux at a temperature of about 90 to 10,000, with a molar ratio of aldehydes to phenol of 1 or less, similar to the general method for producing novolac resins. After the reaction is complete, add an alkaline substance such as caustic soda, caustic potash, calcium hydroxide, etc. to pH 6~
Neutralize to 7 and leave to cool. The reaction product liquid is separated into an aqueous phase and a resin phase by cooling, and the upper aqueous phase is separated and removed, and a surfactant, polyvinyl alcohol, and an oxide or hydroxide of an alkali metal or zinc are added to the resin liquid. Surfactants act as foaming regulators.
Silicon-based (for example, manufactured by UCC, L-52 stop L-5
30, L-5320, etc.), nonionic activators (e.g., polyoxyethylene sorbitan monolaurate (Kao Atlas Co., Ltd., Tween 20), polyoxyethylene sorbitan monopalmitate (Kao Atlas Co., Ltd., Tween 40), polyoxyethylene nonylphenol Solbon F80 (manufactured by Toho Chemical Co., Ltd.), etc.) are used. The amount of these additions is 0 for 10 parts of phenols (hereinafter referred to as parts by weight).
．． 5 to 3 parts to completely dissolve it in the resin phase.
Polypynyl alcohol is added as an aqueous solution in an amount of 0.05 to 1 part per 100 parts of phenol to completely disperse and dissolve it in the resin phase. In addition, oxides or hydroxides of alkali metals (calcium, barium, magnesium, etc.) or zinc act as hardening aids, and when the purpose is to produce low-foaming products, 10 parts of phenols are used. 2 to 10 parts of this, or 0.3 parts for highly foamed products.
Add ~2 parts. When these are completely dissolved in the resin phase, heated and dehydrated, a transparent novolac resin is obtained. heating,
A foaming agent, a curing agent, and if necessary, a scale agent, pigment, etc. are added to the resin phase after dehydration. Examples of the blowing agent include substances that generate gas when heated, such as dinitrosobentamethylenetetramine, azodicarbonamide, benzenesulfonyl hydrazide derivatives, toluenesulfonyl hydrazide derivatives, azoisobutyrodinitrile, and sodium bicarbonate. This is added in an amount of 1 to 12 parts per 10$ of novolak resin. Hexamethylenetetramine and paraformaldehyde are used as curing agents, and are added in an amount of 8 to 16 parts per 100 parts of the novolac resin. Add 1 to 3 parts of other nourishing agents such as stearic acid, calcium stearate, and magnesium stearate, coloring agents (dyes, pigments), etc., as appropriate, mix thoroughly using a mixer such as a pole mill or ribbon blender, and further heat roll, The mixture is thoroughly kneaded and pulverized using a co-kneader or the like to obtain a foamable composition. A foam having uniform to fine particles can be obtained by molding this composition into a tablet or plate shape at a low temperature and placing it in a molding box or mold and heating it in a heating furnace to foam and harden it. Since the novolak resin according to the present invention dissolves surfactant and polyvinyl alcohol during its synthesis process, it has fine foamed particles and is homogeneous due to the bubble control and bubble stabilization effect of the gas generated during foam curing. gives a foam.

Furthermore, since the metal compound added as a curing agent exists as a metal compound with formaldehyde salt or novolac resin, the foam does not become non-uniform and a phenol resin having good moldability is provided. Example 1 Production of wind novolak resin 7 parts of oxalic acid was added as a catalyst to 635 parts of 37% formalin and 100 parts of foam was emulsified. After emulsification, the reaction was carried out under reflux for 2 hours, and a 2% by weight caustic soda aqueous solution was added. After neutralizing with 22 parts, leave to cool.

11 parts of Tween 20 as a surfactant is added to the resin liquid from which the upper aqueous phase has been removed and completely dissolved. Next, 2 parts of a 1% by weight aqueous solution of polyvinyl alcohol are added and also completely dissolved. Finally, 5 parts of magnesium oxide was added as a hardening aid and heated and dehydrated until the melting point was 70q.
A reddish-brown transparent novolak resin with a rating of ○ was obtained. [B) Manufacture of foaming composition 100 parts of the obtained novolak resin, 15 parts of hexamethylenetetramine as a hardening agent, 6 parts of dinitrosobentamethylenetetramine as a foaming agent, and 2 parts of stearic acid were ground and mixed using a ball mill. , high temperature side 80~90q
The mixture was kneaded for 8 to 10 minutes using rolls at a low temperature of 25 to 30°C, cooled, and then crushed to obtain a foamed paper composition.

{q Foam molding The obtained foaming composition 310 layers was molded into a board with 31 sides x 31 sides and a thickness of 2.5 mm, and 31 arcs x 31 inches x 5 (depth)
It was placed in an arc molding box and foamed in a heating oven at 12,000° C. for 4 minutes, and then at 160° C. for 30 minutes.

The bulk specific gravity of the obtained foam was 0.050, and a homogeneous highly foamed material having fine foamed particles was obtained. Example 2
In Example 1 of Production of Borac Resin, 35 parts of calcium hydroxide was added instead of magnesium oxide, and heat dehydration was performed to obtain a melting point of 7.
A reddish-brown transparent novolac resin of 50 ml was obtained.

'B - Manufacture of foaming composition 100 parts of the obtained/borac resin were ground and mixed with 15 parts of hexamethylenetetramine, 2 parts of dinitrosobentamethylenetetramine, 2 parts of stearic acid, and 2 parts of pigment using a ball mill. The mixture was kneaded for 5 to 10 minutes using rolls with a temperature of 90 to 100° C. on the high temperature side and 25 to 30° C. on the low temperature side, and after cooling, was crushed to obtain a foaming composition.

} Foam molding The resulting foamed composition No. 17 was molded into a tablet with a diameter of 5 mm and a thickness of 1 mm, which was placed in a mold and heated in a 150 qo heating furnace for 30 minutes to foam and harden.

The high specific gravity of the obtained foam was 0.43, and a homogeneous low-foamed material having fine foamed particles was obtained. Comparative Example 1 ■ Manufacture of novolak resin 100 parts of phenol and 635 parts of 37% formalin were emulsified by adding 7 parts of oxalic acid as a catalyst, followed by a reaction under reflux for 2 hours, followed by 22 parts of a 2% by weight aqueous solution of caustic soda. After neutralizing with water, the mixture was allowed to cool, and the remaining resin liquid after removing the upper aqueous phase was heated and dehydrated to obtain a novolac resin with a melting point of 70 qC.

'B} Manufacture of foaming composition Obtained nopolak resin
100 parts, 15 parts of hexamethylenetetramine, 6 parts of dinitrosobentamethylenetetramine, 20 parts of Tween
1 part of stearic acid and 1 part of stearic acid were pulverized and mixed in a ball mill to obtain a foaming composition in the same manner as in Example 1 {B--.

{C} Foam molding The obtained foaming composition 310 was foamed and cured in the same manner as in Example 1'q to obtain a foam with a high specific gravity of 0.048, but the foamed particles were coarse and non-uniform. .

Comparative Example 2 Novolak resin similar to Comparative Example 1: 15 parts of catalytic hexamethylenetetramine, 2 parts of dinitrosobentamethylenetetramine, 201 parts of Tween, 2 parts of magnesium oxide, 2 parts of stearic acid, and 2 parts of pigment in Example 2 { B
A foaming composition was obtained in the same manner as described above.

Claims (1)

[Claims] 1. Phenols and aldehydes are reacted in the presence of an acidic catalyst, the reaction product is neutralized, the aqueous phase is separated and removed from the resin phase, and a surfactant, polyvinyl alcohol, and alkaline earth metal or zinc oxide or Add hydroxide, heat and dehydrate, then add foaming agent and curing agent,
A method for producing a phenolic resin foam, which comprises kneading, heating, foaming, and curing.