JPH0363990B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical field to which the invention pertains) The present invention relates to a method for producing a phenolic resin foam having closed cells and a uniform fine cell structure. Phenol resin foams are used for various purposes due to their excellent properties such as fire resistance and heat insulation. In general, methods for producing phenolic resin foam include a method using a mixture of novolac type phenolic resin and hexamethylenetetramine, and a method using a mixture of resol type phenolic resin mixed with a blowing agent, a surfactant, and an acidic curing agent. It is being The present invention relates to a method for producing a phenolic resin foam using a resol-based phenolic resin. (Prior Art) Resol-based phenolic resins can generally be produced by reacting a phenolic compound and an aldehyde compound under controlled reaction conditions and in the presence of a controlled excess amount of the aldehyde compound. . Foaming is performed by mixing a certain amount of a foaming agent, a foam stabilizer, and an acidic curing agent with a resol type phenolic resin, and applying a temperature of room temperature or 40 to 120°C. The phenolic resin foam thus obtained is generally considered to have 40-100% open cells. This is caused by destruction of the cell walls and cracks, voids, etc. in the center of the foam. As an improvement on the above problems, JP-A-56-30438
There is. This involves adding N-methyl-2-pyrrolidone to obtain uniform cells. (Problems to be Solved) However, although the phenolic resin foam obtained in the presence of N-methyl-2-pyrrolidone had a slight effect of making the cells uniform and fine, there were many continuous cells. Therefore, the present inventors conducted extensive research to obtain a phenolic resin foam having closed cells and a uniform fine cell structure. It has been discovered that the phenolic resin foam which is the object of the present invention can be obtained by mixing in a . (Structure of the Invention) That is, the present invention uses polyoxyethylene polyoxyalkylene ricinoleic acid ether as a foam stabilizer when producing a phenolic resin foam from a resol type phenolic resin, a blowing agent, a foam stabilizer, a curing agent, etc. This is a method for producing a phenolic resin foam, characterized in that 0.1 to 10 parts by weight are added to 100 parts by weight of resol type phenolic resin. The polyoxyethylene polyoxyalkylene ricinoleic ether used in the present invention is represented by the following structural formula. n=10-50 m=5-20 n≧m+5 R=propylene or butylene The balance of hydrophilicity and hydrophobicity strength (HLB) changes depending on the amount of ethylene oxide and alkylene oxide added, but the polyoxylic acid used in the present invention The HLB of ethylene polyoxyalkylene ricinoleic acid ether varies depending on the type of resol type phenolic resin, but is 8.5 to 17.5, preferably 10 to
15 is good. The amount of the foam stabilizer to be used is preferably 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the resol type phenolic resin. If the amount exceeds 10 parts by weight, a foam with a closed-cell fine cell structure will be formed, which is not preferable because mechanical strength, heat resistance, and fire resistance will decrease. When the amount is less than 0.1 part by weight, a foam having a uniform fine cell structure of closed cells cannot be obtained. Various compounds can be used as the phenol compound or aldehyde compound used in the production of the resol-based phenolic resin. Phenol compounds include both phenols and their congeners such as cresols and xylenol or mixtures of these compounds. Aldehyde compounds that react with phenolic compounds include, for example, formaldehyde, acetaldehyde, flubral, and other aldehydes and mixtures of these compounds. Furthermore, aldehyde-forming compounds can also be used, such as paraformaldehyde, hexamethylenetetramine,
Compounds that decompose to formaldehyde such as methylol, trioxane, tetraoxymethane and others and mixtures of these compounds can also be used. The reaction between a phenolic compound other than phenol and an aldehyde other than formaldehyde or its complex form is slower than the reaction between phenol and formaldehyde. Therefore, in the present invention, it is preferable to use a resol type phenol resin in which phenol and formaldehyde are reacted. Blowing agents that can be used in the present invention include chlorinated and fluorinated hydrocarbons with a boiling point of about -40°C to 100°C;
For example, chloroform, methylene chloride, trichlorofluoromethane, tetrafluoromethane, 1.1.2
-Trichloro-1.2.2-trifluoroethane, monochlorodifluoromethane, dichlorodifluoromethane, 1.1-dichloro-1.2.2.2-tetrafluoroethane, 1.2-dichloro-1.1.2.2-tetrafluoroethane, 1.1.1-trichloro-2.2 .2-trifluoroethane, 1.2-difluoroethane, bromotrifluoroethane, 1.1.2.2-tetrachloro-
Included are 1,2-difluoroethane, 1.1.1.2-tetrachloro-2,2-difluoroethane, or mixtures of these compounds. As the curing agent used in the present invention, mineral acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as P-toluenesulfonic acid and phenolsulfonic acid are used. Alkaline or neutral resol type phenolic resin
By shifting the pH to the acidic side all at once, condensation begins quickly, and foaming begins in the presence of the foaming agent. It is preferable that the polyoxyethylene polyoxyalkylene ricinoleic acid ether of the present invention is used by being mixed in advance with a resol type phenolic resin. Any method may be used for mixing and foaming the resol type phenolic resin containing polyoxyethylene polyoxyalkylene ricinoleic acid ether and other raw materials as long as the reaction mixture can be mixed uniformly. For example 1500～
It can be obtained with known mixing devices such as gear type or bottle type mixers at 10000 rpm. (Effects of the Invention) The characteristics of the phenolic resin foam obtained by the present invention are as follows. (1) Compared to conventional resol-based phenolic resin foams, it has a higher closed cell ratio and exhibits superior heat insulation performance. (2) There are no cracks or voids in the foam center, and the foam has a uniform fine cell structure, so the foam has high mechanical strength. (3) It has little effect on foam foaming and curing, and can be foamed using normal methods. (4) It has flame retardancy, low smoke emission, and heat resistance equivalent to conventional phenolic resin foam. As described above, the resol-based phenolic resin foam according to the present invention has closed cells, has a uniform fine cell structure, and has excellent heat insulation properties, heat resistance, and flame retardancy, and therefore can be widely used in the field of building materials. (Examples and Comparative Examples) Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Examples 1 and 2 The reaction mixture shown in Table 1 was weighed into a polyethylene beaker (1), stirred vigorously for 10 to 30 seconds with a mixer (rotation speed: 8000 rpm) at room temperature (20 to 25°C), and then heated to a temperature of 50°C to 80°C. It was foamed in an aluminum mold with an open top heated to .degree. C. and cured in an oven at 80.degree. C. to 120.degree. C. for about 10 minutes to obtain a resol-based phenolic resin foam. After two weeks of dehydration at room temperature, the foam properties were measured. Compared to Comparative Example 1 in which a silicone surfactant was used as a foam stabilizer, the closed cell ratio was higher and the thermal conductivity was lower. Visual inspection revealed that there were no tears or large voids in the center of the foam, and it had a uniform and fine cell structure. Examples 3 and 4 A resol type phenol resin foam was obtained using the mixture shown in Table 1 in the same manner as in Example 1. Compared to Comparative Example-2, the closed cell ratio was higher.
Moreover, the heat resistance at 150°C was also good. Visual inspection revealed that the cell structure was uniform and fine. Examples 5 and 6 A resol type phenol resin foam was obtained using the mixture shown in Table 1 in the same manner as in Example 1. It had a high closed cell ratio and a uniform fine cell structure. Comparative Example 1 The resol type phenolic resin foam obtained from the mixture shown in Table 1 not only had a lower closed cell ratio than Examples 1 and 2, but also had large cells as a result of visual inspection, indicating that the cell structure was defective. It was uniform and warm. Comparative Example 2 The resol type phenolic resin foam obtained from the mixture shown in Table 1 not only had no closed cells at all, but also had a non-uniform cell structure. Comparative Example 3 As a result of using N-methyl-2-pyrrolidone as a foam stabilizer, the cell structure became uniform and fine, but the number of closed cells did not increase.

【table】

[Table] The blending amount numbers in the table indicate parts by weight. Foam stabilizer-A: Polyoxyethylene polyoxypropylene ricinoleate ether (HLB=12) Foam stabilizer-B: Polyoxyethylene polyoxybutylene ricinoleate ether (HLB=12) Phenol resin-A: Viscosity is 2500 cp/25 phenol, whose solid content is 75%
Formaldehyde (resole phenol)
Resin Phenol Resin-B: Phenol with a viscosity of 1000 cp/25°C and a solid content of 75%,
Formaldehyde (resole phenol)
Resin silicone surfactant (foam stabilizer): Toray Silicone SH-193 Foaming agent: Trichlorotrifluoroethane Curing agent: 65% phenolsulfonic acid aqueous solution Foam density: Measured according to JISA-9514 Compressive strength: Measured according to JISA-9514 Brittleness: The smaller the measured value according to ASTMC-421, the less brittle the foam is. Closed cell ratio: Measured according to ASTMD-2856 Thermal conductivity: Measured according to JISA-9514 Smoke emission coefficient: Using a 220 x 220 x 30 mm test piece
According to the JISA-1321 flame retardant grade 2 A surface test, the smaller the measured value, the lower the amount of smoke emitted. Heat resistance: Leave a 100 x 100 x 50 mm test piece in an oven at 150°C for 24 hours and measure deformation, cracks, etc. Items with little deformation and no cracks are acceptable.

Claims (1)

[Claims] 1. When producing phenolic resin foam from resol-based phenolic resin, blowing agent, foam stabilizer, curing agent, etc., polyoxyethylene polyoxyalkylene ricinoleic acid ether is added as a foam stabilizer to 100 parts by weight of resol-based phenolic resin. 0.1~10
A method for producing a phenolic resin foam, which comprises adding parts by weight.