JPH10237208A - Expandable phenolic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can given 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 novolac 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 solvent has a lower alcohol/ketone solvent ratio of 80/20 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 or paraformaldehyde, and the organic decomposable blowing agent used is exemplified by N,N'-dinitrosopentamethylenetetramine or benzenesulfonyl hydrazide.

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]

Means for Solving the Problems The present invention has been intensively studied to solve the above-mentioned problems, and as a result, a novolak type phenol resin, a curing agent, an organic decomposition type foaming agent and a foam stabilizer have been added to lower alcohols. And a mixed solvent of a ketone-based solvent and a uniform molded body without foaming unevenness, good impregnation into fibers, etc., easy preparation of the resin component in the solvent, and composition of the mixed solution. It has been found that a foamable phenolic resin composition which is stable without any precipitates can be obtained.

That is, by using a mixed solvent of a lower alcohol and a ketone-based solvent, the novolak-type phenol resin and the curing agent are dissolved in the lower alcohols, and the phenol resin and the organic decomposition-type blowing agent are dissolved in the ketone-based solvent. It is confirmed that the novolak-type phenol resin plays a role as a compatibilizer and forms a stable composition without precipitates in a mixed solvent. The body is obtained.

The mixing ratio of the lower alcohol and the ketone solvent used in the present invention is lower alcohol: ketone solvent = 80: 20 to 9:91, preferably 70: 3.
0:20:80. When the amount of the ketone solvent is less than 80:20, the organic decomposition type foaming agent precipitates, and when the amount is more than 9:91, the curing agent precipitates. On the other hand, if the lower alcohol is more than 80:20, the organic decomposition type foaming agent precipitates, and if the lower alcohol is less than 9:91, the curing agent precipitates.

[0008] The lower alcohols used in the present invention include:
Usually, it is an alcohol having 4 or less 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 phenolic resin used in the present invention is obtained by reacting phenols and formaldehyde with an acidic catalyst according to a conventional method.
The phenols of the novolak type phenolic resin used in the present invention include phenol, orthocresol, metacresol, paracresol, xylenols, alkylphenols, resorcinol, catechol, bisphenol A, bisphenol F, etc., alone or in combination of two or more. You may use together. 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.

[0010] The organic decomposition type blowing agent used in the present invention includes:
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, for example, hexamethylenetetramine, paraformaldehyde and the like. 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.

[0012]

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.
00 parts, as a curing agent A, hexamethylenetetramine 5
Parts, 1.5 parts of N, N'-dinitrosopentamethylenetetramine as foaming agent A, 0.5 parts of oxyethylene block polymer as foam stabilizer A, 35 parts of methyl alcohol as solvent A, and 136 parts of acetone as solvent B The mixture was stirred and mixed to obtain a mixed solution A having a nonvolatile content of 37%. 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 solution A was impregnated and dried on a glass nonwoven fabric according to a conventional method, and then dried at 150 ° C.
For 10 minutes, and evaluated for uneven foaming.

Example 2 100 parts of novolak type phenolic resin A, 1.6 parts of benzenesulfonyl hydrazide as foaming agent B, 1 part of silicone oil as foam stabilizer B, 50 parts of solvent A, and 50 parts of solvent B A mixed solution B having a nonvolatile content of 50% was obtained in the same manner as in Example 1 except for the above. Less than,
Confirmation and evaluation were performed in the same manner as in Example 1.

(Example 3) [0015] Except that 100 parts of novolak type phenol resin A, 1.5 parts of foaming agent B, 0.7 parts of foam stabilizer A, 102 parts of ethyl alcohol as solvent C, and 69 parts of methyl ethyl ketone as solvent D were used. In the same manner as in Example 1, mixed liquid C having a nonvolatile content of 38% was obtained. 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 benzenesulfonylhydrazide as a foaming agent B, and 1 part of silicone oil as a 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 406 parts of the solvent A.
I got Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

Comparative Example 3 A mixed solution E having a nonvolatile content of 49% was obtained in the same manner as in Example 2 except that the solvent was changed to 99 parts of the solvent B. Hereinafter, confirmation and evaluation were performed in the same manner as in Example 1.

Table 1 shows the results of confirmation and evaluation of Examples 1 to 3 and Comparative Examples 1 to 3.

[Table 1]

As is clear from Table 1, the foamed phenolic resin composition obtained by dissolving a novolak type phenolic resin, a curing agent, an organic decomposition type foaming agent and a foam stabilizer in a mixed solvent of a lower alcohol and a ketone solvent is used. Compared to the powdery phenolic resin resin and the foamable phenolic resin composition of a single solvent, the state of the mixed solution and the state at the time of dilution are good, indicating that there is no foaming unevenness and uniformity.

[0021]

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 (2)

[Claims] 1. A novolak type phenol resin, a curing agent,
A foamable phenol resin composition in which an organic decomposition type foaming agent and a foam stabilizer are dissolved in a mixed solvent of a lower alcohol and a ketone solvent. 2. The foamable phenolic resin composition according to claim 1, wherein the mixing ratio of the mixed solvent is lower alcohol: ketone solvent = 80: 20 to 9:91.