JPS6372737A - Production of phenolic resin foam - Google Patents

Abstract

PURPOSE:To obtain a foam having a uniform and fine cellular structure and excellent in surface smoothness, processability, etc., by mixing a resol phenolic resin with a specified antifoamer, adding a blowing agent, a foam stabilizer and a curing agent to the mixture and foaming and curing the resulting mixture. CONSTITUTION:100pts.wt. resol phenolic resin is mixed with 0.1-2pts.wt. antifoamer of an HLB or 7-9 (e.g., polyethlene glycol octylphenyl either). A blowing agent (e.g., trichlorotrifluoroethane), a foam stabilizer (e.g., polyoxyalkylene nonionic surfactant) and a curing agent (e.g., phenolsulfonic acid), and the resulting mixture is foamed and cured. In this way, a high-density phenolic resin foam of a density of 80-300kg/m<3> can be obtained. No void appears even when the obtained phenolic resin foam is cut in any direction, and it can be desirably used as a forming material for sculpture, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a phenolic resin foam having a uniform fine cell structure, excellent surface smoothness, and excellent machinability.

(Prior Art) Clay has traditionally been used as a molding material for sculptures, vehicle designs, etc., but hard clay with excellent surface smoothness is used so that it can be painted. However, since clay is heated to soften it before use, it takes time to process it, and it also takes time to correct it. Therefore, in recent years, hard plastic foams such as polystyrene foams and polyurethane foams, which are easy to cut, have been used as materials for mass production in place of clay.

(Problems to be solved by the invention) However, polystyrene foam has poor solvent resistance;
The post-painting process is perfect. Furthermore, since the rigid polyurethane foam does not have a fine cell structure, it has poor surface smoothness, and when post-painting, it is necessary to prepare the surface to make it smooth and then apply the coating. Furthermore, in terms of machinability, the machinability of curved lines was poor.

Therefore, the inventors of the present invention focused on a phenolic resin foam that has fine cells, has excellent surface smoothness, and is highly machinable.However, resol-based phenolic resin foams tend to have voids in the foam. There was a quality problem in that voids appeared on the surface of frames that were cut into various sizes.

The object of the present invention is to solve these drawbacks and to obtain a high-density foam that always has excellent surface smoothness and a uniform fine cell structure no matter which direction it is cut.

(Means to Solve the Problem) That is, the present invention provides a method for foaming and curing a resol-based phenolic resin in the presence of a foaming agent, a foam stabilizer, an antifoaming agent, a curing agent, etc. 0.1 to 2.0 of the agent per 100 parts by weight of resol type phenolic resin!
This is a method for producing a 7-nol resin foam, which is characterized in that a high-density foam with a density ff of 180 to 30,047 is obtained by using the following method:

Generally resol type 7:L-Nol resin foam (hereinafter referred to as

If a foam (simply referred to as a foam) is too brittle, it will have good machinability, but the foam itself will be brittle and unable to maintain its shape. In order to reduce brittleness, it is necessary to increase the density of the foam, but if the density of resol-based phenolic resin foam is increased, there will be voids in the foam, making it impossible to obtain a good foam. . The reason for the occurrence of voids in foams is that in the curing reaction of phenolic resins that produce high-density foams, the heat of reaction is rapidly high, and some of the water vapor generated in the reaction is partially absorbed by the resulting gel state. This is thought to be caused by being confined.

In the present invention, by using a foam stabilizer and an antifoaming agent together, when the phenol resin is forming a cured foam, the antifoaming agent partially destroys the foam film, and the generated water vapor is transferred to the foam. Temporarily escape outside of l! It was foamed again by the action of the I foaming agent and a film was formed, thereby making it possible to obtain a void-free foam.

Antifoaming agents that can be used in the present invention are generally nonionic surfactants, such as polyethylene glycol-based, polypropylene glycol-based, polyalkylene glycol-based, and sorbitan fatty acid ester-based surfactants.
Those with LB of 7 to 9 are preferred. It is generally known that antifoaming agents with an HLB of 5 or less have a high antifoaming effect, but when used in the present invention, the antifoaming effect is so strong that foaming does not occur. Moreover, when HIaB is 10 or more, there is almost no defoaming effect and voids are generated in the foam.

The amount of antifoaming agent used is: resol type phenolic resin 1
0.1-0 with an antifoaming agent of HLB'7 to 9 per 00 parts by weight.
2. The oz amount is preferably 0.2 to LO parts by weight.

2. If the amount exceeds O3i parts, the defoaming effect will be too large and a foam having a fine cell structure will not be obtained. Also Q, 1
If the amount is less than part by weight, even if an HLB5 antifoaming agent is used, voids will occur in the foam and a good foam will not be obtained.

As the foam stabilizer that can be used in the present invention, polyoxyalkylene-based or silicone-based nonionic surfactants can be used alone or in combination.

The resol type phenolic resin used in the present invention is composed of a phenol compound and an aldehyde compound, and various compounds can be used. Phenolic compounds include both phenol and its congeners such as cresol and xylenol or mixtures of these compounds. Aldehyde compounds that react with phenolic compounds include, for example, formaldehyde, acetaldehyde, furfural, and other aldehydes as well as mixtures of these compounds. Furthermore, aldehyde-forming compounds can also be used, such as paraformaldehyde, hexamethylenetetramine, methylol, trioxane,
Tetraoxymethane.

Compounds that decompose to formaldehyde, such as K and others, and mixtures of these compounds can also be used.

The reaction between a phenolic compound other than phenol and formaldehyde, i9 is an aldehyde other than its complex form, is
7: The reaction between L-nol and formaldehyde is slow. Therefore, in the present invention, it is preferable to use a resol type phenol resin in which 7-nol and formaldehyde are reacted.

As the blowing agent, halogenated hydrocarbons can be used. Chlorinated and fluorinated hydrocarbons with a boiling point of about -40°C to 100°C, such as chloroform, methylene chloride, trichlorofluoromethane, tetrafluoromethane, 1.1.2-
) dichloro-1,2,2-trifluoroethane, monochlorodifluoromethane, dichlorodifluoromethane, 1
．． 1-dichloro-1,2,2,2-tetrafluoroethane, l,2-cyclo1.1.2.2-tetrafluoroethane.

1.1. l-)dichloro-2,2,2-)9fluorox
p7,1.2-difluoroethane, bamotrifluoroethane, 1.1.2.2-tetrachloro-1゜2-difluoroethane, l, l, l, 2-tetrachloro-2,2-difluoroethane or these Mixtures of compounds are included.

Hardening agents used in the present invention include mineral acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and P-)luenesulfonic acid.

Organic acids such as phenolsulfonic acid are used,
By adding these, the pH of the alkaline or neutral resol type Funol resin is shifted to the acidic side all at once, so that condensation immediately begins and foaming begins in the presence of the foaming agent.

(Effects of the Invention) The characteristics of the foam obtained by the present invention are as follows.

(1) No matter which direction the foam is cut,
Excellent surface smoothness with no voids.

(2) Since this foam has a uniform fine cell structure, it can be directly painted without any surface treatment.

(3) This foam has excellent machinability and can be curved.

As described above, the foam according to the present invention has excellent surface smoothness and machinability, so it can be widely used as a material for machine making.

Of course, it can be used not only as a material for molding, but also in fields where the characteristics of this foam can be utilized.

(Examples and Comparative Examples) Next, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples.

(Example - 5) The reaction mixture shown in Table 1 was weighed into a 1 t polyethylene beaker, and stirred vigorously for 0 to 90 seconds at room temperature (20 to 25°C) using a mixer (rotation speed: 800 rpm). , 150m x 150w preheated to 40-50℃
Foamed in a wooden mold of 150 m x 80 m after the reaction was completed.
The foam was obtained by airing in the open at ~100° C. for about 10 minutes.

After being left at room temperature for about two weeks to dehydrate, the physical properties of the foam were measured. The resulting foam was divided into four parts and the generation of voids in the foam was observed, but no voids were observed.

(Comparative Example-1) As shown in Table IK, a foam was obtained in the same manner as in Example-1 using a blended mixture without using an antifoaming agent.

All of the four divided foams had large voids, and the cell structure was not uniform and fine.

(Comparative Example-2) As shown in Table-1, foaming was performed in the same manner as in Example-1 using an antifoaming agent with a low HIJB, but no foaming occurred and a good foam was not obtained. .

(Comparative Example-3) A blended mixture as shown in i-1 was foamed in the same manner as in Example-1 to obtain a foam.

When the foam was divided into four parts, each foam had voids.

Resol type phenolic resin foam stabilizer with phenolic resin biviscosity of 500 cps (25°C) and solid content of 62%: Daiichi Kogyo Seiyaku Noogen aX antifoaming agent: Polyethylene glycol octylphenyl ether (HIJB9) Antifoaming agent B: Polyethylene glycol nonylphenyl ether (nbB7) Defoaming agent 0: Polyethylene glycol nonylphenyl ether (HLB5) Defoaming agent D = polyethylene glycol octyl 7-ether (HLBIO) Foaming agent Nitrichlorotrifluoroethane curing agent:
65% Tunorsulfonic acid aqueous solution foam Density f: Measured by JI8A 9514 Compressive strength: JI8A 9514 #Brittleness
: According to ASTM O421) The larger the measured value, the more brittle the foam is.

Claims (1)

[Claims] HL
Using 0.1 to 2.0 parts by weight of antifoaming agent B7 to 9 to 100 parts by weight of resol type phenolic resin, the density is 80 to
A method for producing a phenolic resin foam, characterized by obtaining a high-density foam of 300 Kg/m^2.