JPH0214224A - Production of foamed phenolic resin - Google Patents

Abstract

PURPOSE:To obtain the subject foamed material having excellent charging efficiency and dense cell structure and suitable as a heat-insulation material for building use by compounding a specific phenolic resin with a surfactant, a foaming agent and an acidic curing agent and foaming and curing the mixture. CONSTITUTION:The objective foamed material can produced by foaming and curing a mixture produced by compounding (A) a resol-type phenolic resin having a viscosity of 5-20poise/25 deg.C and a number-average molecular weight of 140-400 and produced by reacting (i) 1mol of a phenolic compound with (ii) 1.4-1.8mol of a formaldehyde compound and (iii) 0.035-0.15mol of an alkali metal or alkaline-earth metal hydroxide with (B) a surfactant (e.g., castor oil), (C) a foaming agent (e.g., carbon tetrachloride) and (D) an acidic curing agent (e.g., hydrochloric acid).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a resol type phenolic resin foam used as a heat insulating material for building materials. More specifically, the present invention relates to a method for producing a resol type phenolic resin foam that exhibits good filling properties during foaming and has a dense cell structure.

C. Prior Art] Resol type phenolic resin foam has superior properties such as flame retardancy and low smoke emission compared to other plastic foams such as polyurethane foam, polystyrene foam, urea resin foam, and polyethylene foam. It is something that you have. Generally, when producing a foam, there is a drawback in that the fluidity of the resin is poor and good filling properties cannot be obtained. In particular, when filling and foaming sand inch panels, metal sizing, etc., the poor foam filling properties of resol type phenolic resins are a disadvantage in production.

The reason for this is that the resol type phenolic resin for foaming generally has a high viscosity of 40 to 80 poise/25°C. Since the phenol resin has a high viscosity, the viscosity of the mixture containing surfactants, blowing agents, acidic curing agents, etc. is also high, and the fluidity of the mixture during foaming is poor, resulting in poor filling properties. When the viscosity of conventional resol type phenolic resins was lowered, foams having a fine cell structure could not be obtained.

In order to compensate for the low filling properties of resol-type phenolic resins when foaming, the number of discharge ports in the mixing head of the compound injection machine is usually increased, but this is still insufficient and the foam is left with no glue. There were major restrictions on the shape of the foam.

[Problem to be solved by the invention]

The present inventors have completed the present invention as a result of various studies on methods for improving the foam filling properties during production of resol type phenolic resin foams.

[Means to solve the problem]

The present inventors have developed a method for producing a phenolic resin foam by foaming and curing a foaming material containing a resol-type phenolic resin, a surfactant, a blowing agent, and an acidic curing agent as essential components. In order to improve the fluidity of the resin, we set the resin viscosity to a low viscosity of 5 to 20 poise/25°C, and we also investigated the possibility that the resulting foam would have a dense cell structure. Reaction using 1.4 to 8 mol of formaldehyde per mole and 0.035 to 0.15 mol of alkali metal hydroxide or/and alkaline earth metal hydroxide as a resolization reaction catalyst. However, it has been found that this is possible by using a resol type phenolic resin, which has a viscosity of 5 to 20 poise/25° C. and a number average molecular weight of 140 to 400, which is extremely limited.

[Effect]

In general, resol-type phenolic resins for foaming are oligomers produced by reacting phenols and aldehydes with an alkali catalyst.Usually, phenols and aldehydes are mixed in a ratio of 1 to 1 mole of II to 1 mole of the former. After reacting in the presence of an alkali catalyst at a ratio of 0 to 2.5 moles, the pH was adjusted to 5.5 to 8 with an acid. Obtained by neutralization with O and dehydration. When a surfactant and a foaming agent are added and mixed to a resol type phenolic resin, and then an acidic substance is added and mixed as a hardening agent, the resol type phenol resin causes an acidic curing reaction, and undergoes gelation and hardening. During this time, due to an exothermic reaction,
Foaming occurs because the foaming agent evaporates, and a cured foam having a cell structure is generated due to the effect of the surfactant.

Generally, conventional resol type phenolic resins for foaming have a high viscosity of 40 to 80 poise/25°C. When synthesizing resol type phenolic resin, if the amount of dehydration is reduced and the viscosity is set to low, the acidic curing reaction will be significantly reduced, so the resin will harden after the blowing agent has finished vaporizing.
Since the timing of foaming and resin curing was different, the foaming ratio decreased and a foam with a dense cell structure could not be obtained. If the molecular weight of the resol-type phenolic resin is lowered in order to prevent a decrease in the acidic curing reaction of the resin as much as possible, the expansion ratio will be considerably improved, but the cells of the foam will become extremely coarse.

When synthesizing a resol type phenolic resin, the present inventors used phenols and formaldehyde in an amount of 1.4 to 1.8 mol of the latter per 1 mol of the former, and 1 mol of phenol.
11 mol of alkali metal hydroxide or/and alkaline earth metal hydroxide in the presence of 0.035 to 0.15 mol, and the resulting viscosity is 5 to 20 poise/25°C.
It has been found that by using a resin having a number average molecular weight of 140 to 400, it is possible to reduce the viscosity of the resin and produce a foam having good cells. Even though this limited resol type phenolic resin has a low viscosity, it undergoes a quick acidic curing reaction and produces a good foam.

In the present invention, as the phenol, phenol, cresol, xylenol, ethylphenol, bisphenol A1 bisphenol F, etc. can be used alone or in combination. Examples of aldehydes include formaldehyde,
Acetaldehyde, furfural, etc. are used alone or in combination.

Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.; examples of alkaline earth metal hydroxides include calcium hydroxide, magnesium hydroxide, barium hydroxide, etc. alone or in combination; It is used in a proportion of 0.035 to 0.15 mol per 11 mol of phenol. When the amount of alkaline earth metal hydroxide or/and alkaline earth metal hydroxide used is less than 0.035 mol per 1 mol of phenol, the acidic curing reaction decreases and a good foam cannot be obtained. do not have. If the amount exceeds 0.15 mol, a foam with a dense cell structure can be obtained, but the powdering property and water absorption of the foam become too large to be put to practical use.

The number average molecular weight of the resol type phenolic resin of the present invention is 1
40 to 400, and the viscosity at 25°C is 5 to 400.
It is 20 poise. When the number average molecular weight is less than 140, although the acidic curing reaction during foaming is fast, a foam with a dense cell structure cannot be obtained.
If it exceeds 0, the acidic curing reaction during foaming becomes slow, the foaming ratio decreases, and a good foam cannot be obtained.

If the viscosity at 25°C is 5 poise, the acid curing reaction during foaming will be delayed, the expansion ratio will be reduced, and a foam containing fine cells will not be obtained.

If the viscosity exceeds 20 poise/25° C., the fluidity of the blend during foaming decreases, and the original purpose of improving foam filling properties is lost.

As the surfactant in the present invention, conventionally known surfactants for producing resol foam can be used. For example, silicone oil, ethylene oxide adduct of alkylphenol, polyoxyethylene etherified product of castor oil or coconut oil, sorbitan ester type. etc. Moreover, these can also be included in the resol type phenol resin in advance.

As the blowing agent, conventionally known blowing agents for producing resol foam can be used. For example, carbon tetrachloride, petroleum ether,
Isopropyl ether normal pentane, trichloromonofluoromethane, dichlorodifluoromethane, monochlorotrifluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, tetrachlorodifluoroethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, methylene chloride or a mixture thereof may be used. It is possible.

Examples of acidic curing agents include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid;
and organic acids such as phenolsulfonic acid and para-toluenesulfonic acid.

Resol type phenolic resin foam is produced by mixing a predetermined amount of surfactant, blowing agent, acid curing agent, etc. with resol type phenolic resin, injecting the mixture in combination with various face materials, and then heating it to room temperature to 100°C. obtained by foaming and curing,
Sand inch panels, sizing materials and various laminates are produced. It is also possible to add inorganic materials, flame retardants, anti-corrosion additives, etc.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited by these Examples. In addition, "parts" and "%J" described in production examples and comparative examples are all "Parts by weight J" and "% by weight" are shown.

Example 1 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1380 parts of 37% formalin (formaldehydes/phenols molar ratio (hereinafter referred to as F/P molar ratio) -
1.60), and then 42 parts of potassium hydroxide (potassium hydroxide/phenol molar ratio -0.07) was added. After the temperature was gradually raised to 80° C. and the mixture was reacted for 1.5 hours, 75 parts of 36% hydrochloric acid was added to neutralize the mixture. The dehydration reaction is carried out under vacuum, and the viscosity at 25°C is 10 poise.
1430 parts of a resol type phenolic resin having a pH of 7.0 and a number average molecular weight of 280 was obtained.

Example 2 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1294 parts of 37% formalin (F/P mol = 1.50
), and then 43 parts of sodium hydroxide (sodium hydroxide/phenol molar ratio -1.10) was added. After the temperature was gradually raised to 70°C and the reaction was continued for 4 hours, 25 parts of sulfuric acid was added to neutralize. The dehydration reaction was carried out under vacuum, and the viscosity at 25°C was 8 poise and Pi (7.1
, resol type phenolic tree 11 with a number average molecular weight of 355
360 copies were obtained.

Example 3 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1466 parts of 37% formalin (F/P molar ratio -1,70
), then 17 parts of sodium hydroxide (sodium hydroxide/phenol molar ratio -0.04) and 73 parts of barium hydroxide (barium hydroxide/phenol molar ratio -0.04).
, 04) was added.

After the temperature was gradually raised to 80° C., the mixture was reacted for 1 hour, and then at 70° C. for 2 hours, 38 parts of para-toluenesulfonic acid was added to neutralize the mixture. The dehydration reaction is carried out under vacuum, and the viscosity at 25°C is 14 poise and the pH is 7.2.
, resol type phenolic resin 1 with a number average molecular weight of 188
320 copies were obtained.

Comparative Example 1 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1380 parts of 37% formalin (F/P molar ratio = 1.6
0) was charged, and then 7 parts of sodium hydroxide (sodium hydroxide/phenol molar ratio -0.016) was added. After the temperature was gradually raised to 80°C and the mixture was reacted for 3 hours, 35 parts of lactic acid was added to neutralize it. The dehydration reaction was carried out under vacuum, and the viscosity at 25°C was 55 poise and the pH was 7.
．． 1290 parts of a resol type phenolic resin having a number average molecular weight of 212 was obtained.

Comparative Example 2 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1380 parts of 37% formalin (F/P molar ratio -1,60
), and then 7 parts of sodium hydroxide (sodium hydroxide/phenol molar ratio -0,016) was added. After the temperature was gradually raised to 80°C and the mixture was reacted for 3 hours, 35 parts of lactic acid was added to neutralize it. The dehydration reaction was carried out under vacuum, and the viscosity at 25°C was 10 poise and the pH was 7.
1. 1,340 parts of a resol type phenolic resin having a number average molecular weight of 214 was obtained.

Comparative Example 3 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1380 parts of 37% formalin (F/P molar ratio = 1.6
0) was charged, and then 42 parts of potassium hydroxide (potassium hydroxide/phenol molar ratio = 0.07) was added.

After the temperature was gradually raised to 80° C. and the reaction was continued for 25 minutes, 75 parts of 36% hydrochloric acid was added to neutralize the mixture. A dehydration reaction was carried out under vacuum to obtain 1160 parts of a resol type phenolic resin having a viscosity of 10 poise at 25°C, a pH of 7.1, and a number average molecular weight of 130.

Comparative Example 4 1000 parts of phenol was placed in a reaction vessel equipped with a stirrer and a cooler.
1380 parts of 37% formalin (F/P molar ratio = 1.6
0) was charged, and then 42 parts of potassium hydroxide (potassium hydroxide/phenol molar ratio = 0.07) was added.

After gradually raising the temperature to 80°C and reacting for 3 hours,
75 parts of 36% hydrochloric acid was added to neutralize. The dehydration reaction was carried out under vacuum, and the viscosity at 25°C was 11 poise and the pH was 7.
．． 0.1520 parts of a resol type phenolic resin having a number average molecular weight of 421 was obtained.

For 100 parts of each resol type phenolic resin obtained in Examples 1, 2.3 and Comparative Examples 1.2, 3.4, 2 parts of surfactant (Kao r TW-5120J),
10 parts of a blowing agent (Freon 1°13), and an acidic curing agent (
13 parts of 67% phenolsulfonic acid aqueous solution was mixed with a special mixing injection machine at a mixing head rotor rotation speed of 40.
The mixture was mixed at 0.00 rpm, heated to 70°C in advance, poured separately into aluminum molds with an open top, and then heated in a dryer at 70°C for IO minutes to foam and harden each resol type phenolic resin foam. I got a body.

During this time, the reactivity during foaming was measured. Next, the obtained resol foams were taken out and cured at 23° C. for 10 days, and then the foam physical properties of each resol foam were measured.

Next, each of the above formulations was separately injected from the end into a sandwich panel iron plate structure of length 180 cm x width 3 Q cm x thickness 2.5 crs placed in a real press heated to 80°C in advance. Each resol-type phenolic resin foam-filled sandwich panel was obtained by foaming and curing by heating for a minute.

Each sandwich panel obtained was disassembled, and the filled resol foam was measured for the length of the foam in the longitudinal direction/foam weight as a fluidity index, and the filling rate of the resol foam in the sandwich panel was measured. It was measured.

The characteristics of these resol type phenolic resin foams are as follows.
Shown in the table. As is clear from Table 1, the method of the example has good fluidity and filling properties during foam curing, and the physical properties of the foam are also excellent.

〔Effect of the invention〕

According to the method of the present invention, it is possible to obtain a resol type phenolic resin foam that has excellent foam filling properties during production, has no pores, and has a fine cell structure, and is suitable as a building material. This method is suitable as a method for manufacturing a heat insulating material.

Claims (1)

[Claims] (1) In a method for producing a phenolic resin foam by foaming and curing a foaming material containing a resol-type phenolic resin, a surfactant, a blowing agent, and an acidic curing agent as essential ingredients, the resol-type phenolic resin is combined with phenols. 1.4 to 1.8 moles of formaldehyde per mole of phenols, and 0.035 moles of alkali metal hydroxide or/and alkaline earth metal hydroxide per mole of phenols. A phenolic resin foam characterized by being a resol type phenolic resin having a viscosity of 5 to 20 poise/25°C and a number average molecular weight of 140 to 400 obtained by reaction in the presence of ~0.15 mol. manufacturing method.