JPH10237207A - Expandable phenolic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can give a uniform molding without uneven expansion, has good impregnability into e.g. a fiber, whose resin content can be easily adjusted with a solvent and which does not settle and is stable by dissolving a mixed novolac/resol phenolic resin, a curing agent, an organic decomposable blowing agent and a foam stabilizer in a mixed solvent comprising a lower alcohol and a ketone solvent. SOLUTION: The mixed phenol resin has a novolac/resol ratio of 91/9 to 9/91. The mixed solvent has a lower alcohol/ketone solvent ratio of 91/9 to 9/91. The lower alcohol used is usually a 4C or lower alcohol such as methanol or ethanol and may be a mixture of at least two alcohols. The ketone solvent used is exemplified by acetone or methyl ethyl ketone and may be a mixture of at least two ketones. The curing agent used is exemplified by hexamethylenetetramine, and the organic decomposable blowing agent used is exemplified by N,N'-dinitrosopentamethylenetetramine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamable phenolic resin composition useful for heat insulating materials, cushioning materials, panels, boards and the like reinforced with fibers and the like.

[0002]

2. Description of the Related Art Conventionally, glass wool, rock wool, phenol, urethane foam and the like have been used for heat insulating materials, cushioning materials, panels and the like. However, glass wool, rock wool and the like are excellent in workability and flexibility, but inferior in strength. Although phenol foam improves strength to some extent,
There is brittleness. In order to improve brittleness and mechanical strength, use of reinforcing fibers has been considered. As a method of mixing various reinforcing fibers in a phenol foam, Japanese Patent Publication No. 47-8945 discloses a method in which a powdery foamable resin composition is sprayed between a plurality of laminated cotton-like sheets, and then heated rolls are formed. There has been proposed a method in which a preform is formed at a temperature at which the powdered foamed resin can be melted by hot pressing or the like, the resin is impregnated inside each cotton sheet, and the laminated molded body is foamed and cured by heating. However, in this method, foaming hardening does not occur, and impregnation is performed at a low temperature at which the resin melts, but the allowable temperature range is narrow.Also, although the heating temperature is low, foaming hardening occurs partially by heating, There is a problem of foaming unevenness due to spraying.

[0003] Also, Japanese Patent Application Laid-Open No. 61-233526,
JP-A-61-233527 adopts a method in which a cotton-like substance is previously impregnated with a liquid substance in which a powdery resin is compatible, and it is improved that partial foaming hardening of the powdery resin occurs. It is difficult to add a foaming agent, a plasticizer, and the like, and there are problems such as uneven foaming. In order to solve the problems such as uneven foaming, JP-A-2-173131 discloses a sheet-shaped nonwoven fabric which is impregnated with a composition obtained by dissolving a novolak-type phenol resin, a curing agent, a foam stabilizer and the like in a solvent in which novolak is soluble. In Japanese Patent Publication No. 5-75779, a sheet-shaped nonwoven fabric is impregnated with a composition in which a mixed phenolic resin of a novolak type phenol resin and a resol type phenol resin, a foaming agent, and a foam stabilizer are dissolved in a solvent in which the mixed resin is soluble. A method has been proposed. However, when impregnating a sheet-shaped nonwoven fabric with a resin component and impregnating the resin, if a single solvent is used, the solubility of the foaming agent, the curing agent, and the resol-type phenolic resin of the mixed phenolic resin becomes poor, and precipitates are generated. It becomes a turbid liquid and the problem of uneven foaming is considered. In the case of a mixed phenolic resin, only the resole type phenolic resin acts as a curing agent, which may cause a problem in the strength of the molded article.

[0004]

SUMMARY OF THE INVENTION An object of the present inventors is to obtain a uniform molded article without uneven foaming.
An object of the present invention is to provide a foamable phenol resin composition which has good impregnation into fibers and the like, can easily prepare a resin component with a solvent, does not precipitate the composition of the mixed solution and is stable.

[0005]

The present invention has been made as a result of intensive studies to solve the above-mentioned problems, and as a result, a mixed phenolic resin of a novolak type phenol resin and a resol type phenol resin, a curing agent, an organic decomposition type foaming agent By dissolving the foaming agent and the foam stabilizer in a mixed solvent of lower alcohols and ketone solvents, a uniform molded body can be obtained without uneven foaming, good impregnation into fibers, etc. Was easily obtained, and a stable foamable phenol resin composition was obtained without precipitation of the composition of the mixed solution.

That is, a novolak type phenol resin,
A mixture of a curing agent, an organic decomposition type foaming agent and a foam stabilizer dissolved in lower alcohols precipitates without the compatibility of the foaming agent, but the mixed phenolic resin with the resole type phenol resin improves the solubility of the foaming agent. It was confirmed that a mixed solution without precipitate was obtained. However, when this mixture is further diluted with lower alcohols, a resol-type phenol resin and a foaming agent are precipitated. The use of a mixed solvent containing a mixed phenolic resin and a ketone-based solvent compatible with the blowing agent to improve solubility has been confirmed to form a stable composition without precipitates. As a result, a uniform molded article without uneven foaming was obtained.

The mixing ratio of the lower alcohol and the ketone solvent used in the present invention is lower alcohol: ketone solvent = 91: 9 to 9:91, preferably 80:20.
20:80. When the amount of the ketone solvent is less than 91: 9, the resol type phenol resin and the organic decomposition type foaming agent are precipitated, and when the amount is more than 9:91, the curing agent is precipitated. On the other hand, if the lower alcohol is more than 91: 9, the resol type phenol resin and the organic decomposition type foaming agent are precipitated, and if the lower alcohol is less than 9:91, the curing agent is precipitated.

[0008] The lower alcohols used in the present invention include:
It is usually an alcohol having 4 or more carbon atoms such as methanol and ethanol, and may be used alone or in combination of two or more.
The ketone solvents used in the present invention include acetone, methyl ethyl ketone, and the like, and may be used alone or in combination of two or more. Further, solvents such as ethers, esters, and amines may be added to such an extent that the solubility is not deteriorated.

The novolak type phenol resin and the resol type phenol resin used in the present invention are prepared by reacting phenols and formaldehyde with an acidic catalyst in the case of the novolak type and a basic catalyst in the case of the resol type according to a conventional method. It was made. The phenols of the novolak type phenolic resin and the resol type phenolic resin used in the present invention include phenol, orthocresol, metacresol, paracresol, xylenols, alkylphenols, resorcinol, catechol, bisphenol A, bisphenol F, and the like. They may be used alone or in combination of two or more. As the aldehydes, formaldehyde, paraformaldehyde, acetaldehyde, furfural and the like can be used, and they may be used alone or in combination of two or more.

As the acidic catalyst used in the synthesis of the novolak type phenol resin, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid and the like can be used. Further, as the basic catalyst used in the resol synthesis, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonium, triethylamine and the like can be used.

The organic decomposition type foaming agent used in the present invention comprises:
Organic blowing agents such as N, N'-dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, and azobisisobutyronitrile can be used, and they may be used alone or in combination of two or more. As the foam stabilizer, generally used surfactants such as silicones, alkylphenol / ethyl oxide adducts, higher alcohol sulfates and higher fatty acids may be used alone or in combination of two or more.

In the present invention, a conventional curing agent can be used as a novolak curing agent, and examples thereof include hexamethylenetetramine and paraformaldehyde. Inorganic and organic fillers may be added as modifiers to such an extent that the properties of the foamable phenolic resin composition of the present invention are not deteriorated. Also, sodium cellulose glycolate, polyvinyl alcohol, polyvinyl butyral, sodium polyacrylate, methylcellulose, sodium alginate,
Casein, starch, water-soluble polymers such as polyethylene glycol and plasticizers such as glycerin, tung oil, rubber substances,
Flame retardants such as ammonium phosphate and trichloroethyl phosphate may be added.

[0013]

The present invention will be described below with reference to examples. However, the present invention is not limited by the examples.
Further, “parts” and “%” shown in Production Examples, Examples, and Comparative Examples are “parts by weight” and “% by weight”.

Example 1 A novolak-type phenolic resin A1 obtained by reacting phenol and formaldehyde in a reaction vessel equipped with a stirrer and a cooler using an acid catalyst according to a conventional method.
100 parts, 100 parts of a resol-type phenol resin A having a nonvolatile content of 80% obtained by reacting phenol and formaldehyde with a basic catalyst according to a conventional method, 5 parts of hexamethylenetetramine as a curing agent A, and N, N ′ as a blowing agent A -1.5 parts of dinitrosopentamethylenetetramine, foam stabilizer A
Then, 100 parts of methyl alcohol as solvent A and 100 parts of acetone as solvent B were added to 0.5 part of oxyethylene block polymer and stirred and mixed to obtain a mixed solution A having a nonvolatile content of 47%. The sediment of the obtained mixed liquid and the sediment of the case where it was diluted to 20% of the non-volatile content with the solvent of the usage ratio and the case where it was diluted to 20% of the non-volatile content with the solvent A were confirmed.
Further, the obtained mixed liquid A was impregnated and dried in a glass nonwoven fabric according to a conventional method, and then foamed and cured at 150 ° C. for 10 minutes to evaluate foam unevenness.

(Example 2) 100 parts of novolak type phenolic resin A, 50 parts of resol type phenolic resin A 1.6 parts of benzenesulfonyl hydrazide as foaming agent B, 1 part of silicone oil as foam stabilizer B, 194 parts of solvent A, solvent A mixed solution B having a nonvolatile content of 35% was obtained in the same manner as in Example 1 except that B was changed to 48 parts. Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

Example 3 A mixture C having a nonvolatile content of 48% was obtained in the same manner as in Example 1 except that 102 parts of ethyl alcohol was used as the solvent C and 69 parts of methyl ethyl ketone was used as the solvent D. Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

(Comparative Example 1) 100 parts of novolak type phenolic resin A, 1.6 parts of benzenesulfonyl hydrazide as foaming agent B, and 1 part of silicone oil as foam stabilizer B were kneaded with a heating roll, and then pulverized to powder resin A. Obtained. The obtained powdered resin A was sprinkled on a glass nonwoven fabric, melt-impregnated with a hot roll, foamed and cured at 150 ° C. for 10 minutes, and the unevenness of foaming was confirmed and evaluated.

Comparative Example 2 A mixed solution D having a nonvolatile content of 20% was prepared in the same manner as in Example 1 except that the solvent was changed to 693 parts of the solvent A.
I got Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

Comparative Example 3 Example 2 was repeated except that 100 parts of novolak type phenol resin A and 99 parts of solvent B were used.
In the same manner as above, a mixed solution E having a nonvolatile content of 49% was obtained. Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

The results of confirmation and evaluation of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[Table 1]

As is clear from Table 1, a mixed phenolic resin of a novolak type phenol resin and a resol type phenol resin, a curing agent, an organic decomposition type foaming agent and a foam stabilizer are dissolved in a mixed solvent of a lower alcohol and a ketone solvent. The foamed phenolic resin composition that is made is better in the state of the mixed solution and the state at the time of dilution than the foamable powdery phenolic resin resin and the foaming phenolic resin composition of a single solvent and a single resin, and there is no foaming unevenness. It shows that it is uniform.

[0022]

As is clear from the above description, the foamable phenolic resin composition of the present invention can provide a uniform molded article without uneven foaming, and can easily adjust the resin ratio with a solvent. A stable resin composition is obtained without precipitation of the composition, and is suitable for a foamable phenol resin composition such as a heat insulating material, a buffer material, a panel, and a board.

Claims (3)

[Claims] 1. A foamable phenolic resin in which a mixed phenolic resin of a novolak type phenolic resin and a resol type phenolic resin, a curing agent, an organic decomposition type foaming agent and a foam stabilizer are dissolved in a mixed solvent of a lower alcohol and a ketone solvent. Composition. 2. The mixing ratio of the mixed phenolic resin is novolak type phenolic resin: resol type phenolic resin = 9.
The foamable phenolic resin composition according to claim 1, wherein the ratio is 1: 9 to 9:91. 3. The foamable phenolic resin composition according to claim 1, wherein the mixing ratio of the mixed solvent is lower alcohol: ketone solvent = 91: 9 to 9:91.