JPH04285642A - Production of phenolic resin foamed product - Google Patents

Abstract

PURPOSE:To produce a phenolic resin foamed product having a good heat- insulating effect and free from the decomposition and cracks of the cell walls by subjecting a reaction system comprising a specific resin mixture, an acidic curing agent mixture, a surfactant and a foaming agent to heating, forming and curing processes. CONSTITUTION:(A) A resin mixture comprising A1: 100pts.wt. of a resol type phenolic resin having a number-average mol.wt. of 300-400, a weight-average mol.wt. of 600-1000, a mol.wt. distribution of 2-2.5 and a water content of 2-8wt.% and A2: 3-25pts.wt. of an alkylene glycol and/or an aromatic alcohol is mixed with (B) an acidic curing agent mixture comprising B1: 100pts.wt. of an aromatic sulfonic acid (e.g. benzene sulfonic acid) having a total water control of <=5wt.% including crystal water and B2: 5-70pts.wt. of an alkylene glycol and/or an aromatic alcohol in an A:B weight ratio of 100:(2-70). The mixture is further mixed with (C) a surfactant in an amount of 1-5pts.wt. based on the component A and (D) a foaming agent in an amount of 5-25pts.wt. based on the component A, and mixture is heated, foamed and cured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resol type phenolic resin foam that exhibits excellent heat insulation properties.

0002

BACKGROUND OF THE INVENTION Phenol resin foam has the best flame retardancy among organic foams and is smokeless, so it is widely used as a heat insulating material for buildings.

[0003] This phenolic resin foam generally contains a resol type phenolic resin, a blowing agent, a surfactant, an acid curing agent, and other additives added as necessary.
For example, it is manufactured by foaming and curing a mixed composition containing flame retardants, neutralizers, thickeners, etc. Due to the occurrence of holes, etc., the foaming agent with low thermal conductivity is dissipated from the phenolic resin foam that is the molded product. For this reason, the thermal conductivity of the phenolic resin foam increases and its heat insulation performance decreases. In particular, when fluorocarbon, which has extremely low thermal conductivity, is used as a blowing agent, the thermal conductivity increases significantly due to dissipation of the blowing agent from the phenolic resin foam, resulting in a significant decrease in heat insulation performance.

[0004] As a method for obtaining a phenolic resin foam having excellent heat insulating properties, for example, British Patent Publication No. 2089812 discloses a method of foaming a resin composition containing powdered aluminum hydroxide. A method for molding a phenolic resin foam is also disclosed in Japanese Patent Application Laid-Open No. 1988-
170128 discloses a method for forming a phenolic resin foam by foam molding a resin composition containing an alkylene dimelamine, and JP-A-59-62645 discloses a method for forming a phenol resin foam under pressure. Each method is explained.

[0005]

[Problems to be Solved by the Invention] By the way, the phenolic resin foam obtained by foam molding the above-mentioned mixed composition containing powdered aluminum hydroxide cannot be added as one component of the composition for foam molding. Since aluminum hydroxide itself is basic, the amount of acid curing agent added to the foam molding composition is inevitably large, and this results in a high humidity level in the phenolic resin foam obtained as a molded product. It has drawbacks such as large dimensional changes and easy corrosion of metals due to sulfuric acid radicals produced by a large amount of acid curing agent. Furthermore, since the aluminum hydroxide added is in powder form, the aluminum hydroxide is not mixed uniformly in the foam molding composition, resulting in a disadvantage that the phenolic resin foam becomes powdery.

[0006] Furthermore, in the method of forming a phenolic resin foam by foam molding a resin composition containing alkylene dimelamine, since alkylene dimelamine itself is basic, a mixed composition containing aluminum hydroxide is used. As in the case of phenolic resin foam obtained by foam molding, the amount of acid curing agent added to the foam molding composition inevitably increases, resulting in a decrease in the humidity of the phenolic resin foam that is the molded product. It has disadvantages such as large dimensional changes due to foam molding, and metals are easily corroded due to sulfuric acid radicals caused by a large amount of acid curing agent.Furthermore, when the foam molded product burns, harmful nitrogen is released. Compounds are produced.

Furthermore, the method for molding a phenolic resin foam described in JP-A-59-62645 consists of foaming and curing a resol-type phenolic resin in a closed pressurizing device. Although a high-quality phenolic resin foam can be obtained without cell wall destruction, cracking, or pinhole formation, this method is suitable for small laboratory equipment, but cannot be used on an industrial scale. When applied to large-scale equipment for continuous production, huge costs are required.

On the other hand, the present invention makes it possible to utilize conventional large-scale non-sealed equipment for continuous production on an industrial scale, and moreover prevents destruction of cell walls, occurrence of cracks, or pinholes. To provide a method for producing a high-quality phenolic resin foam that does not cause the generation of.

[0009]

[Means for Solving the Problems] The method for producing a phenolic resin foam of the present invention involves heating, foaming, and curing a specially prepared reaction system, with a number average molecular weight of 300.
~400, weight average molecular weight 600-1000, molecular weight distribution 2.0-2.5, moisture content 100 parts by weight of resol type phenolic resin and 3-25 parts by weight of alkylene glycol and/or aromatic alcohol. 100 parts by weight of aromatic sulfonic acid having a total water content including crystal water of 5% by weight or less, alkylene glycol and/or aromatic alcohol 5
A second step of preparing an acid curing agent mixture (b) with ~70 parts by weight
The step is to mix 2 to 70 parts by weight of the acid curing agent mixture (B) to 100 parts by weight of the resin mixture (A), as well as a surfactant, a blowing agent, and other optional additive components added as necessary. By adding, the moisture content is reduced to 9% by weight.
The method consists of a third step of preparing the reaction system prepared below, and a fourth step of heating, foaming, and curing the reaction system to obtain a phenolic resin foam.

[0010] In the third step of the method for producing a phenolic resin foam of the present invention having the above-mentioned structure, the surfactant, blowing agent, and other optional additive components added as necessary are added to the resin mixture (I). ), or may be added to the acid curing agent mixture (b),
Prior to mixing the resin mixture (a) and the acid curing agent mixture (b), a surfactant, a blowing agent, and other optional additive components added as necessary are added.

The resol type phenolic resin used to obtain the resin mixture (a) has a number average molecular weight of 300 to 400 and a weight average molecular weight of 600 to 1 as measured by gel permeation chromatography (GPC).
000, the molecular weight distribution is within the range of 2.0 to 2.5,
It is necessary that the moisture content as determined by a Karl Fischer moisture meter is 8% by weight or less, and the reaction catalyst used to synthesize the resol type phenolic resin, the molar ratio between phenols and aldehydes, the reaction temperature, It can be easily produced by a conventionally known method by appropriately controlling the reaction time and the like.

In the method for producing a phenolic resin foam of the present invention, when the number average molecular weight of the resol type phenolic resin used is less than 300, the weight average molecular weight is 600.
If the molecular weight distribution is less than 2.0, or even if the molecular weight distribution is less than 2.0, the reactivity becomes too high, so that the exothermic rate during foam molding becomes faster and the exothermic temperature becomes higher. For this reason, cell wall destruction and cracking occur frequently during the phenol resin foaming process. In addition, when the number average molecular weight exceeds 400, when the weight average molecular weight exceeds 1000, and further,
When the molecular weight distribution exceeds 2.5, the viscosity of the resol type phenolic resin becomes too high, making foam molding itself difficult.

When the moisture content of the resol-type phenolic resin is less than 2% by weight, the viscosity of the resin increases, making it difficult to mold and also increases the exothermic temperature. Cell wall destruction and cracks occur more frequently during the process. In addition, since the moisture originally contained in resol type phenolic resin has a high affinity with the resin, if the moisture content of resol type phenolic resin exceeds 8% by weight, it is used as an acid curing agent. Since the aromatic sulfonic acid cannot completely take in moisture in the phenol resin, this leads to destruction of cell walls and frequent occurrence of cracks and pinholes during the foaming process of the phenol resin.

The aromatic sulfonic acid used in the acid curing agent mixture (b) functions as an acid curing agent, and is a compound represented by the following general formula [Formula 1], for example:
Benzene sulfonic acid, toluene sulfonic acid, xylene sulfonic acid, etc., and naphthalene sulfonic acid are used.

[0015]

[Formula 1] {In the formula, R1, R2, R3 represent a hydrogen atom, an alkyl group, an aryl group, or a hydroxyl group, and R1, R2
, R3 may be the same. }

Aromatic sulfonic acids with a low moisture content, specifically aromatic sulfonic acids with a total moisture content of 5% by weight or less including crystallization water, have a very high affinity for water and cannot be heated or foamed. In order to have a good affinity with the moisture in the reaction system to be cured and to take in the moisture in the reaction system before foaming and curing by the reaction system begins, cell walls are destroyed during the foaming process of the phenol resin. The occurrence of cracks and pinholes is suppressed.

Resin mixture (a) and acid curing agent mixture (b)
The alkylene glycol and/or aromatic alcohol used to obtain the phenol resin act as a reaction inhibitor, and in the resin mixture (a), act as a diluent for the resol type phenolic resin. The agent mixture (b) acts as a diluent for the aromatic sulfonic acid, and the action of this diluent lowers the viscosity and reduces the localization that occurs between the resol type phenolic resin and the acid curing agent. suppresses exothermic reactions.

That is, in the method for producing a phenolic resin foam of the present invention, a water content of 8% by weight is used as one means for suppressing the destruction of cell walls and the generation of cracks and pinholes during the phenol resin foaming process. It is assumed that the following resol type phenolic resin is used, and the dilution effect of the alkylene glycol and/or aromatic alcohol described above is used to prevent the phenolic resin from becoming highly viscous, which makes stirring with a mixer difficult. It is resolved by In addition, aromatic sulfonic acids used as acid curing agents are compounds that exhibit extremely strong acidity.
When this is mixed with the resol type phenolic resin, an exothermic reaction immediately occurs and partial gelation occurs, but in the method of the present invention, this phenomenon can be avoided by using the alkylene glycol and/or
Or it can be solved by the dilution effect of aromatic alcohol.

Examples of the alkylene glycol added as a diluent in order to reduce the above-mentioned viscosity or to suppress locally and rapidly occurring exothermic reactions include ethylene glycol, diethylene glycol, and propylene glycol. Furthermore, these alkylene glycols are made flame retardant by adding a halogen element, and aromatic alcohols include those with low reactivity, such as benzyl alcohol and halogen elements added to this. It is preferable to use materials that have been made flame retardant.

[0020] In the resin mixture (a) of resol type phenolic resin and alkylene glycol and/or aromatic alcohol, the total amount of alkylene glycol and aromatic alcohol is less than 3 parts by weight based on 100 parts by weight of resol type phenolic resin. When this happens, the viscosity cannot be lowered sufficiently due to insufficient dilution of the resol type phenolic resin, and when mixed with the acid curing agent mixture (b), the exothermic reaction is intense, causing moisture in the reaction system and the blowing agent to be removed. Destruction of cell walls, cracks, pinholes, etc. due to this cannot be avoided. Furthermore, if the total amount of alkylene glycol and aromatic alcohol exceeds 25 parts by weight with respect to 100 parts by weight of resol type phenolic resin, the resol type phenolic resin will be diluted too much and the acid curing agent mixture (b) Since the exothermic reaction when mixed with is suppressed too much, it becomes impossible to obtain a molded product that has the appearance of a foam.

Furthermore, in the acid curing agent mixture (b) of aromatic sulfonic acid and alkylene glycol and/or aromatic alcohol, the total amount of alkylene glycol and aromatic alcohol is If the amount is less than 5 parts by weight, if the aromatic sulfonic acid is solid, it will not dissolve, and if it is liquid, it will immediately undergo partial gelation when mixed with the resin mixture (a). It becomes difficult to mold the foam. Furthermore, if the total amount of alkylene glycol and aromatic alcohol exceeds 70 parts by weight based on 100 parts by weight of aromatic sulfonic acid, the aromatic sulfonic acid will be too diluted and will not be mixed with the resin mixture (a). Because the exothermic reaction during this process is too suppressed, it becomes impossible to obtain a molded product that has the appearance of a foam.

In the method of the present invention, in order to obtain a reaction system between a resol type phenolic resin and an acid curing agent, a mixture of a resol type phenolic resin and an alkylene glycol and/or an aromatic alcohol as a reaction inhibitor is used. After preparing a resin mixture (a) and an acid curing agent mixture (b) consisting of a mixture of aromatic sulfonic acid and alkylene glycol and/or aromatic alcohol as a reaction inhibitor, the two are mixed. At the same time, surfactants and foaming agents are essential components in the reaction system, and flame retardants are optional components added as necessary.
The reaction system is prepared by mixing additional components such as a neutralizing agent and a thickening agent.

That is, without directly mixing the resol type phenol resin and the acid curing agent, the resin mixture (a) is made of a mixture of the resol type phenol resin and alkylene glycol and/or aromatic alcohol as a reaction inhibitor. By preparing in advance an acid curing agent mixture (b) consisting of a mixture of aromatic sulfonic acid and alkylene glycol and/or aromatic alcohol as a reaction inhibitor, heating of the reaction system and foaming process can be easily performed. It prevents rapid exothermic reactions and prevents cell wall destruction, cracks, pinholes, etc.

Therefore, in the case where alkylene glycol and/or aromatic alcohol is not mixed in either one of the resin mixture (a) and the acid curing agent mixture (b), the reaction system Partial gelation due to local rapid heat generation cannot be suppressed, and it becomes impossible to mold a foam without destroying cell walls, cracking, or generating pinholes.

In the reaction system between the resol type phenolic resin and the acid curing agent, 2 parts of the acid curing agent mixture (b) are added to 100 parts by weight of the resin mixture (a) having the above-mentioned mixture composition.
If the amount is less than 1 part by weight, complete curing may not be possible depending on the curing temperature and curing time suitable for continuous production due to the lack of acid curing agent, and shrinkage or secondary foaming may occur, resulting in poor quality. A good foam cannot be obtained. In addition, if the acid curing agent mixture (b) exceeds 70 parts by weight with respect to 100 parts by weight of the resin mixture (a) according to the mixed composition, the foaming speed and curing speed will increase due to the excess acid curing agent, resulting in continuous If the curing process is performed at a curing temperature or curing time suitable for production, a foam of good quality cannot be obtained.

Furthermore, when preparing a reaction system between a resol type phenol resin and an acid curing agent using the above-mentioned resin mixture (a) and acid curing agent mixture (b), essential components are added to the reaction system. The surfactants and blowing agents mixed into the resin mixture (a) and the acid curing agent mixture (b) include those conventionally used in the reaction system when molding resol type phenolic resin foams. Similar surfactants and blowing agents are used.

In other words, the surfactant has the function of uniformly dispersing each component in the reaction system and the function of foam regulation. An activator, a silicone nonionic surfactant such as methylpolysiloxane polyalkylene oxide, etc. is used, and 1 part by weight of the resin mixture (a) of resol type phenol resin and alkylene glycol and/or aromatic alcohol is used. It is used in a proportion of about 5 parts by weight.

[0028] As a blowing agent, for example, a low boiling point aliphatic hydrocarbon such as n-hexane, methylene chloride, trichlorofluoromethane, or a halogenated substance thereof may be used as a blowing agent. Resin mixture with alcohol (a) 100
It is used in a ratio of about 5 to 25 parts by weight.

Resin mixture (a) and acid curing agent mixture (b)
Additives added as necessary to the reaction system containing surfactant and blowing agent as essential components include flame retardants, neutralizers, thickeners, etc. As flame retardants, anhydrous Phosphorus compounds such as boric acid and trichloroethyl phosphate also
Aluminum oxide, zinc powder, metal carbonate, earth metal carbonate, etc. are used as neutralizing agents, and sugars are used as thickeners.These optional additives include resol type phenolic resin. and alkylene glycol and/or
Alternatively, it is preferably added in a proportion of 30 parts by weight or less per 100 parts by weight of the resin mixture (a) with aromatic alcohol.

Resin mixture (a) and acid curing agent mixture (b)
In the above reaction system containing a surfactant and a blowing agent as essential components, if the water content in the reaction system exceeds 9% by weight, the alkylene glycol and/or aromatic alcohol in the reaction system may The action of the reaction inhibitor is not good, and excessive moisture in the reaction system makes it impossible to prevent destruction of cell walls, cracks, pinholes, etc. during heating and foaming steps.

[0031]

[Operation] The present invention has a number average molecular weight of 300 to 400, a weight average molecular weight of 600 to 1000, and a molecular weight distribution of 2.0 to 2.
5. Resol type phenolic resin with moisture content of 2 to 8% by weight 1
00 parts by weight and 3 to 25 parts by weight of alkylene glycol and/or aromatic alcohol (a); and 100 parts by weight of aromatic sulfonic acid having a total water content including crystal water of 5% by weight or less. Acid curing agent mixture with 5 to 70 parts by weight of alkylene glycol and/or aromatic alcohol (
After preparing each of (b) and (b), 100% of the resin mixture (a)
By mixing 2 to 70 parts by weight of the acid curing agent mixture (b) and adding a surfactant, a blowing agent, and other optional additive components, a reaction system with a moisture content of 9% by weight or less can be prepared. The process consists of preparing a phenolic resin foam, and then heating, foaming, and curing it to obtain a phenolic resin foam.

[0032] In the method for producing a phenolic resin foam of the present invention having the above-mentioned structure, in order to prevent destruction of cell walls, generation of cracks, generation of pinholes, etc. during foaming and curing of the phenol resin, the water content is However, due to the low moisture content of the resol type phenolic resin, it is difficult to stir the raw material for molding to increase the viscosity. and/or by using a resin mixture (a) with an aromatic alcohol.

Further, in the method for producing a phenolic resin foam of the present invention, a resin mixture (a) of a resol type phenol resin and an alkylene glycol and/or an aromatic alcohol, and an aromatic sulfonic acid and an alkylene glycol and/or This method involves preparing an aromatic alcohol and an acid curing agent mixture (b), and then foam-molding the reaction system of the resol type phenolic resin and the acid curing agent obtained by mixing them. , the rapid exothermic reaction between the resol-type phenolic resin and the acid curing agent is suppressed, and foam molding can be performed without destroying cell walls, generating cracks, or generating pinholes during foaming and curing of the phenolic resin. .

Furthermore, in the method for producing a phenolic resin foam of the present invention, since the moisture content in the reaction system is kept low, the reaction inhibition effect of alkylene glycol and/or aromatic alcohol in the reaction system is extremely good. This effectively prevents cell wall destruction, cracks, and pinhole formation during heating and foaming processes.

[0035]

[Example] Hereinafter, the specific structure of the method for producing a phenolic resin foam of the present invention will be explained based on an example, and the density and thermal conductivity of the obtained phenol resin foam will be explained as compared to those obtained in a comparative example. This will be explained in comparison with the density and thermal conductivity of phenolic resin foam.

Production of resol type phenolic resin (1) A reaction tank with a capacity of 5 liters equipped with a Liebig cooler, a thermometer, a stirrer, a mantle heater and cooling equipment was equipped with 8
1085 g (28.94 mol) of 0% paraformaldehyde, 816 g (10.06 mol) of 37% formalin, and 9
2718 g (26.00 moles) of 0% phenol were added.

[0037] Next, 43.77 g of pelleted KOH
KOH (0.78 mol) dissolved in 208.0 g of water
adding an aqueous solution while operating a stirrer in the reaction tank;
The temperature of the reaction tank was raised from room temperature to 80°C over 40 minutes, and then maintained at 80-82°C for 300 minutes.

Next, a 65% aqueous phenol sulfonic acid solution was added to the reaction tank to adjust the pH to 6.8, and further,
While maintaining the temperature in the reaction tank at 30 to 40°C, the pressure was reduced using an aspirator, and dehydration was completed when the water content in the reaction tank reached 4% by weight, and the number average molecular weight was 385, the weight average molecular weight was 814, and the molecular weight Distribution 2.11, viscosity (25℃) 25
000cp, resol type phenolic resin containing 0.5% free formaldehyde and 8% free phenol (1)
I got it.

Production of resol-type phenolic resin (2) In a 2-liter reaction tank equipped with a Liebig cooler, thermometer, stirrer, mantle heater, and cooling equipment, 8
0% paraformaldehyde 417g (11.13mol)
and 37% formalin 314g (3.87 mol) and 90%
1046 g (10.00 mol) of phenol were added.

[0040] Next, 16.83 g of pelleted KOH
A KOH aqueous solution prepared by dissolving (0.30 mol) in 80.0 g of water was added while operating the stirrer in the reaction tank.
The temperature of the reaction tank was raised from room temperature to 80°C over 0 minutes,
Further, the temperature was maintained at 78-80°C for 270 minutes.

Next, a 65% aqueous phenol sulfonic acid solution was added to the reaction tank to adjust the pH to 6.8, and further,
While maintaining the temperature in the reaction tank at 30 to 40°C, reduce the pressure with an aspirator, and when the water content in the reaction tank reaches 3% by weight, dehydration is completed, number average molecular weight 315, weight average molecular weight 605, molecular weight Distribution 1.92, viscosity (25℃) 80
00cp, resol type phenolic resin containing 0.7% free formaldehyde and 8.3% free phenol (
2) was obtained.

Production of resol type phenolic resin (3) 1085 g (28.94 mol) of 80% paraformaldehyde and 3
816 g (10.06 mol) of 7% formalin and 2718 g (26.00 mol) of 90% phenol were charged.

[0043] Next, 43.77 g of pelleted KOH
KOH (0.78 mol) dissolved in 208.0 g of water
adding an aqueous solution while operating a stirrer in the reaction tank;
The temperature of the reaction tank was raised from room temperature to 100° C. over 50 minutes, and boiling and reflux cooling were further performed over 90 minutes.

Next, a 65% aqueous phenol sulfonic acid solution was added to the reaction tank to adjust the pH to 6.8, and further,
While maintaining the temperature in the reaction tank at 30 to 40°C, the pressure was reduced using an aspirator, and dehydration was completed when the water content in the reaction tank reached 11% by weight, and the number average molecular weight was 397, the weight average molecular weight was 1315, and the molecular weight Distribution 3.31, viscosity (25℃)
6000 cp, resol type phenolic resin containing 0.4% free formaldehyde and 7% free phenol (3
) obtained.

Production of resol type phenolic resin (4) A reaction tank with a capacity of 5 liters equipped with a Liebig condenser, a thermometer, a stirrer, a mantle heater and cooling equipment was equipped with 8
1085 g (28.94 mol) of 0% paraformaldehyde, 816 g (10.06 mol) of 37% formalin, and 9
2718 g (26.00 moles) of 0% phenol were added.

[0046] Next, 43.77 g of pelleted KOH
KOH (0.78 mol) dissolved in 208.0 g of water
adding an aqueous solution while operating a stirrer in the reaction tank;
The temperature of the reaction tank was raised from room temperature to 85°C over 40 minutes, and then maintained at 84-86°C for 210 minutes.

Next, a 65% aqueous phenol sulfonic acid solution was added to the reaction tank to adjust the pH to 6.5, and further,
While maintaining the temperature in the reaction tank at 30 to 40°C, the pressure was reduced with an aspirator, and dehydration was completed when the water content in the reaction tank reached 6% by weight, and the number average molecular weight was 395, the weight average molecular weight was 980, and the molecular weight Distribution 2.48, viscosity (25℃) 20
000 cp, resol type phenolic resin containing 0.7% free formaldehyde and 8% free phenol (4)
I got it.

Example 1 A resin mixture (E-1) of 100 parts by weight of the above-mentioned resol type phenolic resin (1) and 5 parts by weight of ethylene glycol was prepared.
) was prepared.

On the other hand, an acid curing agent mixture (lo-
1) was prepared.

Next, a surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the resin mixture (A-1).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
After adding 2 parts by weight of Resinol F-140] and 15 parts by weight of a blowing agent [DuPont Co., Ltd.: Freon 113], 8 parts by weight of the acid curing agent mixture (RO-1) was added,
Furthermore, a reaction system with a moisture content of 3.0% by weight obtained by stirring this mixture for 15 seconds was injected into an open foaming mold and heated to 70 ° C. to perform foam molding.
Phenolic resin foam [1] which is an example product of the method of the present invention
] was obtained.

Example 2 A resin mixture of 100 parts by weight of the resol type phenolic resin (4) and 9 parts by weight of propylene glycol
2) was prepared.

On the other hand, 100 parts by weight of ethylene glycol was added to 100 parts by weight of solid para-toluenesulfonic acid (total moisture content including crystal water 10.0% by weight) and mixed to dissolve the para-toluenesulfonic acid. After that, 200 parts by weight of liquid xylene sulfonic acid was added and mixed to prepare an acid curing agent mixture (Ro-2).

Next, a surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the resin mixture (A-2).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
After adding 2 parts by weight of Resinol F-140] and 16 parts by weight of a blowing agent [Daikin Industries, Ltd.: Freon 113], 10 parts by weight of the acid curing agent mixture (RO-2) was added, and then The present invention was produced by stirring this mixture for 15 seconds, injecting the resulting reaction system with a moisture content of 4.5% by weight into an open foaming mold, and heating it to 70°C to perform foam molding. A phenolic resin foam [2], which is an example product of the method, was obtained.

Comparative Example 1 A resin mixture of 100 parts by weight of the above resol type phenolic resin (2) and 4 parts by weight of ethylene glycol (E-3)
) was prepared.

On the other hand, the liquid xylene sulfonic acid used in Example 1 (total moisture content including crystal water: 2.0% by weight)
) and 25 parts by weight of ethylene glycol (Ro-1) was prepared.

Next, a surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the resin mixture (A-3).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
After adding 2 parts by weight of Resinol F-140] and 15 parts by weight of a blowing agent [Daikin Industries, Ltd.: Freon 113], 6 parts by weight of the acid curing agent mixture (RO-1) was added, and then The reaction system with a moisture content of 2.4% by weight obtained by stirring this mixture for 15 seconds was poured into an open foaming mold, and the phenol resin was heated to 70°C to perform foam molding. A foam [3] was obtained.

Comparative Example 2 A resin mixture of 100 parts by weight of the above-mentioned resol type phenolic resin (3) and 6 parts by weight of ethylene glycol (E-4)
) was prepared.

On the other hand, the liquid xylene sulfonic acid used in Example 1 (total moisture content including crystal water: 1.0% by weight)
) and 25 parts by weight of ethylene glycol (Ro-1) was prepared.

Next, a surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the resin mixture (A-4).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
After adding 2 parts by weight of Resinol F-140] and 15 parts by weight of a blowing agent [Daikin Industries, Ltd.: Freon 113], 10 parts by weight of the acid curing agent mixture (RO-1) was added, and then The reaction system with a moisture content of 8.6% by weight obtained by stirring this mixture for 15 seconds was poured into an open foaming mold, and the phenol resin was heated to 70°C to perform foam molding. A foam [4] was obtained.

Comparative Example 3 A surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the above-mentioned resol type phenolic resin (1).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
After adding 2 parts by weight of Resinol F-140] and 15 parts by weight of a blowing agent [Daikin Industries, Ltd.: Freon 113], the liquid xylene sulfonic acid used in Example 1 (including crystal water) was added. Total moisture content 1.0% by weight) 10
Adding 6 parts by weight of an acid curing agent mixture (Ro-1) of 0 parts by weight and 25 parts by weight of ethylene glycol, and further stirring this mixture for 15 seconds, the resulting moisture content was 3.6% by weight.
A phenol resin foam [5] was obtained by injecting the reaction system into an open foaming mold, heating it to 70°C, and carrying out foam molding.

Comparative Example 4 Pure water was added to the above resol type phenolic resin (1) to obtain a resol type phenolic resin (5) having a moisture content of 8% by weight and a viscosity of 6000 cp. (5) A resin mixture (A-5) was prepared by mixing 100 parts by weight and 11 parts by weight of ethylene glycol.

On the other hand, by adding pure water to liquid xylene sulfonic acid to obtain xylene sulfonic acid with a moisture content of 5% by weight, 100 parts by weight of the xylene sulfonic acid and 25 parts by weight of ethylene glycol were mixed. , an acid curing agent mixture (Ro-3) was prepared.

Next, a surfactant [NOF Corporation: NS-2] was added to 100 parts by weight of the resin mixture (A-5).
10" 3 parts by weight and a foam stabilizer [Daiichi Kogyo Seiyaku Co., Ltd.:
2 parts by weight of Resinol F-140], 17 parts by weight of a blowing agent [DuPont Co., Ltd.: Freon 113], and a thickener (4 parts by weight).
After adding 10 parts by weight of 0% sucrose aqueous solution), 10 parts by weight of the above acid curing agent mixture (Ro-3) was added, and this mixture was further stirred for 15 seconds to obtain a water content of 9. .6% by weight of the reaction system was poured into an open foaming mold,
A phenol resin foam [6] was obtained by heating to 70° C. and performing foam molding.

[Test] Density of each phenolic resin foam obtained in Examples 1 to 2 and Comparative Examples 1 to 4 and JIS-A
Thermal conductivity of No. 1413 was measured by the flat plate direct method. The results are shown in [Table 1].

[0065] If cell walls are frequently destroyed, cracks occur, or pinholes occur during foam molding, the foaming agent with low thermal conductivity will dissipate from the foam. The thermal conductivity of the foam increases, but if there is little cell wall destruction, cracking, or pinhole formation during foam molding, the foaming agent with low thermal conductivity will be removed from the foam. The result is a foam that does not dissipate, has a low thermal conductivity, and has no change in thermal conductivity due to aging, that is, no deterioration in heat insulation performance.

[0066]

[Table 1]

[0067]

[Effects of the Invention] According to the method for producing a phenolic resin foam of the present invention, a high-quality phenolic resin foam without destruction of cell walls, occurrence of cracks, or generation of pinholes can be produced in a manner similar to that of conventionally used non-sealed foams. Since it can be molded using foaming and curing equipment, phenolic resin foam with good heat insulation properties can be obtained through mass production on an industrial scale, making it highly effective in practical terms. It is.

Claims (1)

[Claims] Claim 1: Number average molecular weight 300-400, weight average molecular weight 600-1000, molecular weight distribution 2.0-2
．． 5. A resin mixture (a) of 100 parts by weight of resol type phenolic resin with a moisture content of 2 to 8% by weight and 3 to 25 parts by weight of alkylene glycol and/or aromatic alcohol, and the total moisture content including crystal water. After preparing an acid curing agent mixture (b) of 100 parts by weight of aromatic sulfonic acid containing 5% by weight or less and 5 to 70 parts by weight of alkylene glycol and/or aromatic alcohol, 10 parts of the resin mixture (a) is prepared.
A reaction system with a moisture content of 9% by weight or less is prepared by mixing 0 parts by weight with 2 to 70 parts by weight of the acid curing agent mixture (b) and adding a surfactant and a blowing agent. A method for producing a phenolic resin foam, which is characterized by subsequently heating, foaming, and curing the foam.