JPS5981344A - Production of phenolic resin foam - Google Patents

Abstract

PURPOSE:To obtain a resol phenolic resin foam of improved corrosiveness, by expanding and curing a resol phenolic resin in the presence of an acid curing agnet, a blowing agent, a surfactant, and lithium hydride. CONSTITUTION:In the production of a phenolic resin foam by expanding and curing a resol phenolic resin in the presence of an acid curing agent, a blowing agent, and a surfactant, lithium hydroxide is added in an amount of 0.1-10pts. wt. per 100pts.wt. resol phenolic resin. The effect of added lithium hydroxide may be as follows. Namely, because lithium hydroxide has a relatively small water-solubility as compared with other strong bases, the neutralization reaction between lithium hydroxide and an acid curing agent does not proceed so fast as to lower the acidity of the resin mixture and thereby adversely affect its expansion and curing. However, after the acid curing agent has served as a foaming/curing agent, the lithium hydroxide reacts relatively rapidly and fully exhibits a neutralization effect. It is therefore possible to produce a foam having uniform, fine, and dense cells.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resol type phenolic resin foam with low corrosivity.

A resol-type phenolic resin foam is usually produced by blending an acidic curing agent, a foaming agent, and a surfactant into a liquid resol-type phenolic resin, and then foaming and curing the mixture.
The foam is heat resistant, flame resistant, low smoke emitting, dimensionally stable,
It is used in a variety of applications because it has excellent properties not found in other plastic foams, such as solvent resistance and low-temperature properties.

However, strong acids such as sulfuric acid and toluenesulfonic acid, which were used as acidic curing agents during the production of the foam, remain in this resol type phenol Ij foam.
It has the disadvantage of corroding metals etc. that come into contact with the foam.

In order to improve this drawback, a mixture consisting of a resol-type phenolic resin, an acidic curing agent, a blowing agent, and a surfactant is added with a metal oxide such as calcium oxide, aluminum oxide, or zinc as a neutralizing agent for the acidic curing agent. Attempts have been made to obtain a resol-type phenolic resin foam with improved corrosion resistance by blending metal powder such as magnesium or the like and uniformly dispersing the mixture, followed by foaming.

However, when metal oxides such as oxidation, calcium, and aluminum oxide, and metal powders such as zinc and magnesium are used as neutralizing agents, they do not dissolve sufficiently in water or resin mixtures and are weakly basic.

Although it has little effect on foaming properties, it has the disadvantage that the rate of neutralization of residual free acids in the produced foam is low and the effect of improving corrosion properties is not sufficient.

Further, a method has also been attempted in which a strong base such as IJ hydroxide or potassium hydroxide is added to the resin mixture as a neutralizing agent. However, when these strong bases are used as neutralizing agents, their solubility in water or resin mixtures is high, and their basicity is also strong, so the reaction with acidic curing agents is too fast, resulting in It has the disadvantage that it reduces the movement of the curing agent as an acid, significantly slowing down the foaming speed, and causing poor foaming.

The present inventors solved the drawbacks of the conventional method described in 4. As a result of testing various neutralizing agents that strengthen resol type phenolic resin foam with improved corrosivity, we found that lithium hydroxide has a corrosive property. It has been discovered that this method is effective in improving

That is, the present invention provides a method for producing a phenolic resin foam by foaming and curing a resol type phenol resin in the presence of an acidic curing agent, a blowing agent, and a surfactant, in which lithium hydroxide is blended into the resol type feed part. The present invention relates to a method for producing a phenolic resin foam characterized by the following.

2. Conventional strong basic power' - reduces the acidity of the acidic curing agent and causes foaming defects (on the other hand, lithium hydroxide, which has the same basicity, does not cause foaming defects and is corrosive). It is surprising that a good foam with improved properties can be produced.

In the present invention, the effect of using lithium hydroxide as a neutralizing agent is extremely remarkable, and although the details of its mechanism of action are not clear, the solubility of lithium hydroxide in water is small compared to other strong bases. However, the neutralization reaction between lithium hydroxide and acidic curing agent is not so fast as to reduce the acidity of the resin mixture and adversely affect foam curing.
After the acidic curing agent acts as a foam curing agent, it reacts relatively quickly with the remaining free acid in the lithium hydroxide six-component foam and has a sufficient neutralizing effect, so it has low corrosivity and eliminates bubbles. It is thought that a uniform and dense foam can be obtained.

The lithium hydroxide used in the present invention is 60 to 1
oo It is preferable to use one that has been pulverized to about the same size as methane. When using IJ lithium hydroxide with a particle size coarser than 60 mesh, not only is the effect of improving the corrosion resistance of the resulting foam to metals etc. insufficient, but also unreacted lithium hydroxide particles remain dispersed in the foam. and adversely affect the appearance of the foam. On the other hand, if lithium hydroxide having a particle size smaller than 100 mesh particles is used, this is not preferable because it will adversely affect the foaming rate.

It is preferable to mix and disperse lithium hydroxide in the resol type phenolic resin in advance, and the amount thereof is 01 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the resol type phenolic resin. If the amount of lithium hydroxide added is less than 0.1 part by weight, the effect of improving the corrosion resistance of the foam to metals etc. is not sufficient. On the other hand, if the amount of lithium hydroxide exceeds 10 parts, it will have an adverse effect on foam curing, making it impossible to obtain a foam car with a homogeneous cell structure.

The resol type phenolic resin is a resol type phenol resin initial condensate obtained by reacting 1 mole of phenols and 0.8 to 3 moles of aldehydes in the presence of an alkaline catalyst. This initial condensate may be partially neutralized with an acid. Examples of phenols include phenol and its homologs such as furesol, xylenol, and alkylphenols. Examples of aldehydes include formaldehyde, malapormaldehyde, acetaldehyde, and furfural.

Examples of acidic curing agents include fN such as phosphoric acid, hydrochloric acid, and sulfuric acid.
41 Examples include strong acids and organic acids such as benzenesulfonic acid, para-1-toluenesulfonic acid, phenolsulfonic acid, and naphtholsulfonic acid. These acidic curing agents may be used as they are or as an aqueous solution. The amount of the acidic curing agent added is preferably 25 to 20 parts by weight per 100 parts by weight of the resol type phenolic resin.

As a blowing agent, trichloromonofluoromethane, 1.1
．． 2-) Low boiling point fluorine compounds such as lichloro-1,2,2-)lifluoroethane, low boiling point chlorine compounds such as carbon tetrachloride and methylene chloride, low boiling point hydrocarbons such as pentane, low boiling point ethers such as isopropyl ether, Solid substances such as alkali metal carbonates and bicarbonates which evolve inert gases, especially carbon dioxide, under the reaction conditions may be mentioned. The amount of blowing agent to be mixed cannot be determined unambiguously because it depends on the type of blowing agent used and the size of the cells of the desired foam, but in general, if the blowing agent is a compound with a low boiling point, , 1 to 40 parts by weight of a low boiling point compound per 100 parts by weight of resol type phenolic resin, and 03 to 10 parts by weight of a solid substance per 100 parts by weight of resol type resin when the blowing agent is a solid substance. It is.

As the surfactant, a nonionic surfactant such as polyoxyalkylene phenyl ether or polyoxyalkylene sorbitan fatty acid ester, or a conventional surfactant such as a silicone thread nonionic surfactant is used. The blending amount of the surfactant is 01 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the resol type phenolic resin.

In the method of the present invention, after lithium hydroxide is mixed with a resol type phenolic resin, an acidic hardening agent is added thereto and the mixture is foamed and hardened. The surfactant and foaming agent may be mixed with the resol type phenolic resin, or may be mixed with the acidic curing agent.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Examples 1 to 3, and Comparative Examples 1 to 2 According to the formulation shown in the table below, resol type phenolic resin for foaming (B RL-2760 manufactured by Showa Union Gosei ■),
2,400-4,000 cps), sorbicun-based nonionic surfactant (manufactured by Kao Atlas Corporation, Tween
40) and lithium hydroxide powder (approximately 80 mesh particle size) were mixed using a high-speed stirrer for 11,515 seconds, and then 1,1,2-trichloro-1,2,2-1-lifluoroethane was added as a blowing agent and mixed for 15 seconds. did. Next, a 65% aqueous solution of phenolsulfonic acid was added as a curing agent to give 1
After mixing for 5 seconds, the inner width is 40 cm and the length is 40 cm.
, in a wooden frame of height 4 C7n. This was left in an atmosphere of 80°C for 20 minutes to complete foaming and curing.
A phenolic resin foam was obtained. Note that the comparative example was also conducted in the same manner as above.

The properties of the obtained phenolic resin foam are shown in the table.

In addition, the pH of the foam is determined by powdering a foam weighing 5 g.
The foam obtained by the method of the present invention was immersed in 500 m6 of pure water and 1 hour later, as shown in the table, the foam obtained by the method of the present invention was
Even if this comes into contact with iron pieces, the iron pieces will not be corroded at all. On the other hand, foams obtained without incorporating lithium hydroxide significantly corrode the iron pieces and cause a large amount of rust. Furthermore, in the case of a foam containing 12 parts by weight of lithium hydroxide, which is outside the range of the present invention, the curing reaction was insufficient after foaming, the shape was distorted, and a homogeneous foam could not be obtained.

Patent applicant Showa Union Gosei Co., Ltd. Agent Patent attorney Sei Kikuchi

Claims (1)

[Claims] In a method for producing a phenolic resin foam by foaming and curing a resol type phenolic resin in the presence of an acidic curing agent, a blowing agent, and a surfactant, 0.0. 1-10
A method for producing a phenolic resin foam, which comprises blending parts by weight.