JPH049175B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an amino resin foam. Polystyrene foam, polyurethane foam, phenolic resin foam, etc. have traditionally been used as sound insulation materials, heat insulation materials, or lightweight base materials for building materials, automobile interiors, etc. However, polystyrene foam has low structural strength and Polyurethane foam has the disadvantage of low heat resistance, extremely poor solvent resistance, and high flammability; polyurethane foam has good structural strength, heat resistance, and solvent resistance, but is extremely flammable and has poor weather resistance. The phenolic resin foam has a slow curing speed, resulting in poor productivity and poor weather resistance. Therefore, recently, attention has been paid to amino resin foams instead of these foams. Conventionally, amino resin foams are produced by adding a chemical blowing agent such as azodicarbonamide or azobisisobutyronitrile to the initial condensate of an amino resin, or a low boiling point solvent such as n-hebutane, n-hexane, or methylene chloride as a blowing agent. It is manufactured by heat foaming and curing the composition added as . However, because these conventional compositions harden quickly, it is difficult to match the timing of foaming and curing, which makes it difficult to foam uniformly, and because they do not form a complete closed cell structure, the sound insulation properties , heat insulation properties etc. deteriorate, and it is difficult to obtain a product with a high expansion ratio. Furthermore, amino resins have inferior flexibility compared to unsaturated polyester resins, epoxy resins, and the like. The present invention aims to improve the above-mentioned conventional drawbacks and provide an amino resin foam that is flexible and has a uniform and independent cell structure. The main idea is to use a plastic synthetic resin capsule. The invention will be explained in detail below. The amino resin referred to in the present invention refers to a condensate of amino compounds such as ureas, melamines, and guanamines and aldehyde compounds such as formaldehyde, paraformaldehyde, and acetaldehyde.
If desired, phenol, alkylphenol, resorcinol, alkylresorcinol, etc. may be co-condensed with the amino resin. It may also be modified with alcohol, polyhydric alcohol, polysaccharide, polyamine, polyisocyanate, furfural, aniline, etc. The blowing agent used in the present invention is a thermoplastic synthetic resin capsule containing a volatile liquid, and the volatile liquid includes n-butane, n-bentane, neobentane, n-hexane, neohexane, cyclohexane, n-octane, Chain or cyclic saturated hydrocarbons such as iso-octane, chain or cyclic unsaturated hydrocarbons such as n-bentene, n-hexene, cyclohexene, n-octene, etc., aromatic hydrocarbons such as benzene, toluene, xylene, etc. , tethers such as ethyl ether, ethyl-propyl ether,
Ketones such as acetone and methyl ethyl ketone, acetate esters such as methyl acetate and ethyl acetate, cellosolves such as cellosolve acetate and butyl cellosolve, alcohols such as methanol and ethanol, trichloromonofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, etc. It mainly contains organic compounds generally called organic solvents, such as fluorinated chlorinated hydrocarbons, methylene chloride, perchloroethylene, and other halogenated hydrocarbons. The thermoplastic synthetic resin constituting the capsule shell is selected to be insoluble in the volatile liquid contained therein, and to have an appropriate softening point depending on the foaming temperature. Examples of such thermoplastic synthetic resins include polyethylene, polypropylene, acrylic resin, methacrylic resin, styrene resin, vinyl chloride resin, vinylidene chloride resin, acrylonitrile resin, vinylbenzyl chloride resin, and the like. The foaming agent is, for example, disclosed in Japanese Patent Publication No. 1973-
Details are given in Publication No. 26524. Other than the above compositions, such as calcium carbonate, white titanium, bentonite, wood flour, wheat flour, coconut flour, walnut flour, silica, fillers such as animal and vegetable fiber pieces, acid and alkali curing catalysts, ε-caprolactam, urea, Condensation preparations such as resorcin or third components such as formalin absorbers, anti-aging agents, ultraviolet absorbers, flame retardants, dyes, pigments, thickeners, etc. may be mixed. To prepare an amino resin foamable composition according to the above composition, the above aldehyde compound is added to the above amino compound in an amount slightly exceeding the equivalent of the amino group contained in the amino compound, and if desired, It is common to add the above-mentioned compound to be co-condensed and other additives to the initial condensate mixture and heat it to room temperature to about 150°C for initial condensation, then add the above-mentioned blowing agent to the initial condensate and disperse it by stirring. However, the above blowing agent may be added without performing initial condensation. The amount of the foaming agent added is 10 to 200 parts by weight per 100 parts by weight of the amino resin. If anything,
If the amount of the foaming agent added is less than 10 parts by weight, sufficient flexibility will not be imparted to the amino resin.
When the amount is 200 parts by weight or more, the heat resistance of the amino resin decreases and it becomes expensive. If desired, a curing catalyst may be added to the amino resin foamable composition of the present invention.
Heat to 80-180℃ to foam and harden. As the condensation reaction progresses during the foaming and curing process, the composition thickens, becomes insolubilized, and finally becomes infusible. Proper foaming is obtained when the condensation reaction system reaches the proper viscosity, ie, when the composition is in a softened state before infusibility. At this stage, the foaming temperature should be adjusted so that the foaming agent capsules soften and are expanded by the vapor pressure of the contained liquid. The blowing agent of the present invention extends the upper air stage. This is because the foaming agent capsule of the present invention is made of thermoplastic synthetic resin and contributes to softening of the composition. Furthermore, the above stage can be sustained by introducing a resorcinol compound or a resorcinol resin into the amino resin. The resorcinol compounds here include resorcinol, 5-methylresorcinol, 5-ethylresorcinol, 5-propylresorcinol, 5-n-butylresorcinol,
4.5-dimethylresorcinol, 2.5-dimethylresorcinol, 4.5-diethylresorcinol,
2.5-diethylresorcinol, 4.5-dipropylresorcinol, 2.5-dipropylresorcinol, 4-methyl-5-ethylresorcinol, 2
-Methyl-5-ethylresorcinol. Refers to alkylresorcinols such as 2-methyl-5-ethylresorcinol, 2.4.5-trimethylresorcinol, 2.4.5-triethylresorcinol, and mixtures thereof. In particular, mixtures of alkylresorcinols obtained by dry distillation of oil-bearing rocks are desirable because they are inexpensive. Furthermore, the resorcinol resin is a condensate of the above resorcinol compound and an aldehyde such as formaldehyde or acetaldehyde. In this way, the amino resin is maintained in the above stage below a certain temperature by adding the above-mentioned resorcinol compound or resorcinol resin, usually in an amount of about 1 to 30% by weight, during which the foaming agent foams and a good foam structure is obtained. The composition is then heated to a temperature higher than the above temperature to promote infusibility of the composition. Such temperature is generally around 100°C. Foaming and curing (infusibility) of the composition may be performed in a mold. The amino resin foam thus obtained has a uniform closed-cell structure and has extremely good heat insulation, sound insulation, and weather resistance. Further, according to the composition of the present invention, the foaming ratio can be increased, a lightweight product can be obtained, and the curing speed is fast, so the productivity of the foam can be greatly improved. Furthermore, since the foam of the present invention contains a thermoplastic synthetic resin as a component of the blowing agent, the brittleness of the amino resin is improved and flexible and tough physical properties can be obtained. Example 1 Add 2 moles of formaldehyde to 1 mole of urea, adjust the pH to 9.0 with sodium hydroxide, and then adjust the pH to 95~
After reacting at 100°C for 60 minutes, the pH was adjusted to 8.2 and dehydration was performed under reduced pressure to obtain a urea-formaldehyde initial condensate having a solid content of 75% by weight and a viscosity of 1500 cps/25°C. A foamable composition prepared using the initial condensate according to the recipe shown in Table 1 was heated at 80° C. for 1 minute to foam and harden to obtain a foam.

[Table] Copolymer Capsule Example 2 Add 2.1 mol of formaldehyde to 1 mol of urea and adjust the pH to 9.5 with sodium hydroxide to 95~
After reacting at 100°C for 50 minutes, the pH was adjusted to 8.0 and dehydration was performed under reduced pressure to obtain an initial urea condensate with a solid content of 75% by weight and a viscosity of 2500 cps/25°C. Using this initial condensate, the second
A foamable composition formulated according to a table-based formulation table.
The foam was cured by heating at 100°C for 30 seconds to obtain a foam.

【table】

[Table]
Example 3 A polyester nonwoven fabric (fabric weight: 40 g) is impregnated with the foamable composition of Example 2 at an impregnating amount of 100 g/m ² , and after drying, it is molded into the shape of an automobile ceiling using a press heated to 110°C. Press conditions are 2Kg/cm ² pressure, 1
It is a minute. According to the above molding, a lightweight molded ceiling base material with extremely good shape stability can be obtained. The results of the performance tests are shown in Table 3.

【table】

【table】

Claims (1)

[Claims] 1. Amino resin monomer or initial condensate 100
An amino resin foam obtained by foaming and curing an amino resin foam composition containing 10 to 200 parts by weight of a thermoplastic synthetic resin capsule containing a volatile liquid as a blowing agent. 2 Amino resin monomer or initial condensate 100
By foaming and curing an amino resin foamable composition in which a resorcinol compound or a resorcinol resin is added to the weight part, and 10 to 200 parts by weight of a thermoplastic synthetic resin capsule containing a volatile liquid is added as a blowing agent. The resulting amino resin foam.