JPH0439493B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Field of Application> The present invention relates to expandable resol resin particles that have excellent storage stability and can be foamed and hardened by heat alone to form a high-quality foam, and a method for producing the same. <Conventional technology> Conventionally, phenolic resin foams were manufactured using
As seen in Publication No. 27772, an aqueous resol resin solution having a solids concentration of 70% to 80%, a blowing agent such as sodium bicarbonate, a hardening agent such as toluenesulfonic acid, and a surfactant such as metal soap are mixed. It is produced by making it into a paste form and heating and foaming it. However, in this method, toluenesulfonic acid is used as a curing agent.
Since large amounts of strong acids such as sulfuric acid and hydrochloric acid are used, the acid remains in the resulting foam, and if the foam is brought into close contact with a metal plate such as an aluminum plate, the metal plate will corrode. There is a problem that the water in the foam cannot be completely removed. In order to solve the above problems, for example, Japanese Patent Publication No. 59-15936 discloses a method of producing a foamable resol resin by kneading resol resin powder produced by emulsion polymerization with a foaming agent and then pulverizing the powder. has been done. However, such a simple blend of resol resin powder and foaming agent,
(a) It is difficult to obtain a foam with uniform cells; (b)
There are many problems such as the difficulty in manufacturing low-density foam, and (c) the complicated manufacturing process as powdered resol resin is re-pulverized after being kneaded. It is extremely difficult to manufacture. <Problems to be Solved by the Invention> As a result of intensive research in order to solve the conventional problems as described above, the present inventors have found that when producing a resol resin by emulsion polymerization of phenols and aldehydes, We discovered that foamable resol resin particles can be easily produced by coexisting a specific compound, and that the resulting foamable resol resin particles foam when heated to form a high-quality foam, which led to the present invention. It has been reached. Therefore, in the present invention, microspherical expandable resol resin particles substituted with a specific group can be foamed by heating alone without using an acid catalyst, and produce a high-quality foam with excellent storage stability. The technical objective is to easily produce the expandable resol resin particles by having excellent stability and easy handling, and by coexisting and reacting with a specific compound. <Means for solving the problems> The features of the present invention that solve the above technical problems are as follows:
Some of the protons of the benzene nucleus have the general formula (In the formula, R ₁ represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ₂ represents an aryl group having 6 to 20 carbon atoms or a functional derivative thereof.)
Substituted with a group represented by and with a particle size of
When reacting phenyls and aldehydes in expandable resol resin particles of 1000 μm or less and an aqueous medium in the presence of a basic catalyst and an emulsion stabilizer, an arylsulfonyl hydrazide compound is coexisted in the reaction system. It's about forcing. Hereinafter, the present invention will be explained in further detail. First, to explain the expandable resol resin particles according to the first invention of the present invention, in the expandable resol resin particles of the present invention, a part of the protons of the benzene nucleus is of the general formula (In the formula, R ₁ represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ₂ represents an aryl group having 6 to 20 carbon atoms or a functional derivative thereof.)
It is substituted with a group represented by. Here, the general formula (In the formula, R ₁ represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ₂ represents an aryl group having 6 to 20 carbon atoms or a functional derivative thereof.)
As the group represented by, for example,

【formula】

etc. can be mentioned. This general formula As will be described later, the substitution of the benzene nucleus of the group represented by the above with a proton is carried out when phenols and aldehydes are reacted in an aqueous solvent in the presence of a basic catalyst and an emulsion stabilizer. Although this is carried out in the presence of a nyl hydrazide compound, a desired degree of substitution can be obtained by appropriately changing the amount of the arylsulfonyl hydrazide compound added. And some of the protons of the benzene nucleus have the general formula The expandable resol resin particles substituted with 1000 μm or less have a microspherical shape. Calcium fluoride, especially as an emulsion stabilizer during the reaction,
Particles made of magnesium fluoride, strontium fluoride, or the like and whose particle surfaces are coated with these salts have excellent storage stability and can be stored for long periods of time without particle fusion. In this way, the foamable resol resin particles of the present invention having the above-mentioned structure have a part of the protons of the benzene nucleus substituted with the above-mentioned specific group, and therefore can be foamed and hardened by heat alone, resulting in high-quality particles. The foam can be made with particle size
Since they are microspherical particles of 1000 μm or less, they are easy to handle during molding and other uses. Next, a method for manufacturing the expandable resol resin particles according to the second aspect of the present invention will be explained. In the method of the present invention, when phenols and aldehydes are reacted in an aqueous medium in the presence of a basic catalyst and an emulsion stabilizer, an arylsulfonyl hydrazide compound is allowed to coexist in the reaction system. The phenols used here are phenol and phenol derivatives, and examples of the phenol derivatives include m-alkylphenol substituted with an alkyl group having 1 to 9 carbon atoms, O-alkylphenol, P-alkylphenol, and Specifically, m-cresol, p-ter-
Butylphenol, O-propylphenol, resorcinol, bisphenol A, and halogenated phenol derivatives in which part or all of the hydrogen atoms of their benzene nucleus or alkyl group are substituted with chlorine or bromine, etc., and one type of these Or two or more types are used. Note that the phenols are not limited to these, and any other compound containing a phenolic hydroxyl group can be used. Further, examples of the aldehydes used in the present invention include formaldehyde in the form of formalin or paraformaldehyde, and furfural, and the molar ratio of the aldehydes to the phenols is 1 to 2, preferably 1.1 to 1.4. be. Furthermore, as the basic catalyst used in the method of the present invention, basic catalysts commonly used in the production of resol resins can be used, such as aqueous ammonia, hexamethylenetetramine, and alkyl amines such as dimethylamine, diethyltriamine, and polyethyleneimine. etc. can be mentioned. The molar ratio of the basic catalyst to the phenols is preferably 0.02 to 0.2. Further, as the emulsion stabilizer used in the method of the present invention, any compound may be used, such as gum arabic, guar gum, PVA,
Organic emulsion stabilizers such as CMC can also be used; in this case, the amount used is 1 to 1 phenols.
~5% by weight is preferred. In particular, calcium fluoride, which the present applicant previously applied for (Japanese Patent Application No. 150399/1982),
Substantially water-insoluble inorganic salts such as magnesium fluoride and strontium fluoride are preferably used from the viewpoint of storage stability of the resulting expandable resol resin particles. The amount of these inorganic salts used is 0.2 to 10% by weight, preferably 0.5 to 10% by weight based on the phenols.
It is 3.5% by weight. Examples of the arylsulfonyl hydrazide compounds that are allowed to coexist when the phenols and aldehydes are reacted in the presence of a basic catalyst and an emulsion stabilizer include benzenesulfonyl hydrazide, p,p'-oxybis(benzene sulfonyl hydrazide, toluenesulfonyl hydrazide, etc., and one or more of these may be used. The arylsulfonylhydrazide compound is not limited to these compounds, and any compound having a sulfonylhydrazide group directly connected to an aromatic nucleus can be used. The amount of the arylsulfonyl hydrazide compound added is 0.1 to 8% by weight, preferably 0.2 to 2% by weight based on the phenols. The reaction of the method of the present invention is carried out in an aqueous medium.
It is preferable to do so. For the reaction, predetermined amounts of phenols, aldehydes, basic catalysts, emulsion stabilizers, water, and arylsulfonyl hydrazide compounds are charged into a reaction vessel under stirring, and the temperature is increased at a rate of 0.5 to 1.5°C/min, preferably 0.8°C. Gradually increase the temperature at ~1.2℃ m/min until the reaction temperature is 70-90℃, preferably 83-87℃.
℃ for 60-150 minutes, preferably 80-110 minutes. In this case, a so-called Mannitz reaction occurs with a part of the phenol, a part of the aldehyde, and the arylsulfonyl hydrazide compound, and the general formula At the same time as the substituent represented by is introduced into the benzene nucleus of some phenols, the polycondensation reaction of phenol/aldehyde proceeds, and the general formula The resol resin has a substituent represented by partially introduced into the benzene nucleus. After reacting in this manner, the reactants are cooled to below 40°C to obtain a stable aqueous emulsion of solid resol. Next, this aqueous emulsion is separated into solid and liquid by a conventional method such as filtration or centrifugation, and then washed with water or water to which a surfactant has been added and dried. The expandable resol resin particles of the present invention having a particle size of 1000 μm or less are obtained. The method of the present invention can be carried out by either a continuous method or a batch method, but is usually carried out by a batch method. The foamable resol resin particles obtained as described above become a foam by heating them alone, but fillers such as wood flour or glass powder may be added at the time of foaming, or they may be used as a foam stabilizer. Surfactants may also be added. <Examples> Hereinafter, the present invention will be specifically explained using examples. Example 1 200g of phenol in 1 three-necked flask, 37
% formalin, 70 g of water, 18 g of hexamethylenetetramine, and 8.4 g of calcium chloride were added with stirring to make a homogeneous solution, and to this solution was added 5.8 g of sodium fluoride, and further 8.0 g of p-toluenesulfonyl hydrazide. g and 85°C for 60 min.
The temperature was raised to 100.degree. C., and the reaction was carried out for 90 minutes at the same temperature to obtain an emulsion of microspherical resol resin. The flask contents were then cooled to 30°C and 0.5
After adding water, the supernatant liquid was removed, and the microspheroidized resin particles in the lower layer were washed with water using a 0.5% aqueous solution of silicone surfactant (L-5340, manufactured by Nippon Unicar Co., Ltd.), and air-dried. This is then dried at 50-60°C under reduced pressure (5 mmHg or less) to reduce the average particle size to approx.
Expandable resol resin particles of 100 μm were obtained. (Resin A) Example 2 200g of phenol in a three-necked flask, 37
Add 200 g of formalin, 70 g of water, 18 g of hexamethylenetetramine, and 8.4 g of calcium chloride while stirring to make a homogeneous solution. To this solution, add 5.8 g of sodium fluoride and 5.0 g of benzenesulfonyl hydrazide while stirring. The temperature was raised to 85° C. over 60 minutes, and the reaction was carried out at the same temperature for 90 minutes to obtain an emulsion of microspherical resol resin. The flask contents were then cooled to 30°C and 0.5
After adding water of . Next, this was dried at 50 to 60° C. under reduced pressure (5 mmHg or less) to obtain expandable resol resin particles with an average particle size of about 100 μm.
(Resin B) Example 3 Expandable resol resin particles with an average particle size of 100 μm were obtained in the same manner as in Example 1, except that the amount of p-toluenesulfonyl hydrazide added was 2.0 g.
(Resin C) Example 4 The amount of benzenesulfonyl hydrazide added
Expandable resol resin particles having an average particle size of about 100 μm were obtained in the same manner as in Example 2 except that the amount was changed to 1.0 g.
(Resin D) Reference Example 1 Resins A to D obtained in Examples 1 to 4 above were each
The foams were placed in cubic containers measuring 10 x 10 x 10 cm and heated in an electric furnace at 160°C for 25 minutes to obtain corresponding foams A, B, C and D. All of these foams had extremely uniform cells with a diameter of 0.5 to 1 mm. Next, the density and compressive strength of the foams A, B, C, and D were measured, and the results shown in Table 1 were obtained. In addition, the compressive strength was measured according to JIS K-7220.

[Table] As is clear from Table 1, the expandable resin particles of the present invention can easily control the density and have good compressive strength. <Effects of the Invention> As described above, in the foamable resol resin particles of the present invention, a portion of the protons of the benzene nucleus is substituted with a specific substituent, so that it can be foamed and cured by heating alone. I can do it. Moreover, the quality of the resulting foam is much better than that of foams made from resol resins produced by conventional methods. Furthermore, since they are microspherical solid particles with a particle size of 1000 μm or less, they are easier to handle during use than conventional solutions or powders. Particularly, those in which calcium fluoride, magnesium fluoride, etc. are used as an emulsion stabilizer during the reaction and the particle surfaces are coated with these salts have excellent storage stability without particle fusion. Furthermore, according to the method of the present invention, the density of the resulting foam can be easily controlled, and there is no need for the process of kneading the resol resin and the blowing agent and the process of crushing the same as in the conventional method, making it extremely economical. Foams can be produced.

Claims (1)

[Claims] 1. Some of the protons of the benzene nucleus have the general formula (In the formula, R ₁ represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and R ₂ represents an aryl group having 6 to 20 carbon atoms or a functional derivative thereof.)
Substituted with a group represented by and with a particle size of
Expandable resol resin particles characterized by a particle size of 1000 μm or less. 2. A foaming resol characterized in that when phenols and aldehydes are reacted in an aqueous medium in the presence of a basic catalyst and an emulsion stabilizer, an arylsulfonyl hydrazide compound is allowed to coexist in the reaction system. Method for producing resin particles. 3. The method for producing expandable resol resin particles according to claim 2, wherein the emulsion stabilizer is at least one selected from the group consisting of calcium fluoride, magnesium fluoride, and strontium fluoride.