JPH0227372B2 - HENSEINYOSOHORUMUARUDEHIDOJUSHIHATSUHOTAI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modified urea resin foam, particularly a urea formaldehyde resin foam having a low density and little shrinkage.

Urea formaldehyde resin foam (hereinafter referred to as UF)
foam) is useful as a heat insulating material and has been widely used in recent years to save energy.
However, UF foams have had major practical problems, such as shrinkage and even cracking after manufacturing when attempting to obtain lower densities than desired for insulation.

UF foam is produced by intervening a surfactant as a foaming agent when curing the initial condensate of urea-formaldehyde-based resin with a curing agent, and by using a gas such as air or carbon dioxide, or ethylene chloride, ethyl acetate, or chlorinated fluoride. Hydrocarbons are produced by foaming with a liquid vaporizable foaming agent such as hydrocarbons at room temperature, but gas foaming causes the moisture content of UF foam to exceed 200% of its air-dry weight immediately after production. It can be said that it is superior in that the value can be reduced to about 60% compared to that, making it suitable for factory production.
The above-mentioned problems are particularly severe when foaming using the above-mentioned vaporizable foaming agent is used.

In view of the above-mentioned circumstances, the inventors of the present invention have made extensive studies and have found a urea resin foam that solves these problems and have completed the present invention.

That is, the present invention provides a urea resin foam obtained by mixing a urea formaldehyde resin initial condensate with a curing agent in the presence of a surfactant and curing the mixture. This is a modified urea resin foam characterized by the combined use of a resin initial condensate.

The urea-formaldehyde-based resin initial condensate in the present invention is a water-soluble or water-dispersible reactant obtained by reacting urea and formaldehyde, and optionally contains compounds such as melamine, dicyandiamide, guanamine, benzoquanamine, and phenol.
It may also be modified by reacting with at least one of lower alcohols such as methanol and ethanol, ketones such as acetone, and aldehydes such as acetaldehyde and glyoxal. In addition, in the case of manufacturing using the above-mentioned vaporizable blowing agent, it is desirable that the urea-formaldehyde resin initial condensate used in the present invention is such that the heat of reaction during curing sufficiently vaporizes the blowing agent; The moisture content is preferably 40% by weight or less, more preferably 30% by weight or less, in order to effectively utilize the heat of reaction as described above and to reduce the moisture content after producing the UF foam. Further, this urea formaldehyde resin initial condensate may contain additives such as methanol, ethanol, ethylene glycol, etc. in order to improve storage stability and cleanability of foaming equipment.

As the surfactant in the present invention, any surfactant that can act as a foaming agent can be used, but anionic surfactants are particularly effective for this purpose, and particularly ammonium lauryl sulfate, sodium dodecylbenzelsulfonate, and higher alcohols. Preferred are sulfuric acid ester sodium salt and sodium alkyl diphenyl ether disulfonate. In the present invention, the surfactant is used by being mixed with the liquid containing the urea formaldehyde resin initial condensate or the liquid containing the curing agent, and the amount thereof is preferably 0.1 to 5% by weight based on the total amount of both liquids. The content is preferably 0.3 to 3% by weight. If this amount is too small, foaming will be insufficient, and if it is too large, the water resistance of the UF foam will be poor.

As the curing agent in the present invention, any acidic substance capable of curing the urea-formaldehyde resin initial condensate can be used, but when the above-mentioned vaporizable foaming agent is used, the heat generated during curing is caused by the same foaming agent. It is desirable to use something that sufficiently vaporizes the Representative examples of preferred curing agents include sulfuric acid, phosphoric acid, hydrochloric acid, para-toluenesulfonic acid, benzenesulfonic acid,
There are acidic substances such as phenolsulfonic acid or their aqueous solutions, and one or more of them are used.
The amount of curing agent used varies depending on the type, the type and ratio of the urea formaldehyde resin initial condensate and resorcinol formaldehyde resin initial condensate used, and the foaming method, but generally the solid content of both of the above condensates 0.5 to 10% by weight,
Preferably it is 1 to 5% by weight.

If the amount of the curing agent is less than this range, the curing of the UF foam will be insufficient, and if it is more than this range, the deterioration due to acid will be severe and the durability will be reduced.

The resorcinol-formaldehyde-based resin initial condensate used in the present invention refers to resorcinols, ie, resorcinol, one or more alkyl substituted products of resorcinol, and aldehyde compounds such as formaldehyde, acetaldehyde, n-butyraldehyde, acrolein, and furfural, or A water-soluble product obtained by reacting at least one aldehyde-generating substance such as paraformaldehyde, hexamethylene diamine, α-polyoxyethylene, etc. as a main component under alkaline or (and) acidic or (and) neutral conditions. Or water dispersible. Of course, it is possible to use amino compounds such as urea, melamine, guanamine, and benzoguanamine, and co-condensed products such as phenols in place of a part of resorcinols, as well as those co-condensed with lower alcohols such as methanol and ethanol.

Also, acetone, caprolactam, etc. may be added as a condensation regulator. Representative examples of alkyl-substituted resorcinol include 5-methylresorcinol, 5-ethylresorcinol, 2,5-dimethylresorcinol, and 2,4,5-trimethylresorcinol.

In the present invention, the resorcinol-formaldehyde-based resin initial condensate is generally added to the urea-formaldehyde-based resin initial condensate immediately before use; may be co-condensed. When the resorcinol-formaldehyde-based resin initial condensate is added to the urea-formaldehyde-based resin initial condensate before use, the amount used is 5 to 5 to 10% solid content relative to the total amount of the urea-formaldehyde-based resin initial condensate. It may be 40% by weight, preferably 10 to 30% by weight. When resorcinols are co-condensed with a urea-formaldehyde resin initial condensate, raw materials other than resorcinols to which aldehydes such as urea, melamine, dicyandiamide, guanamine, benzoquanamine, and phenol can be added may be used. The total amount of resorcinols is 5 to 30% by weight, preferably 10 to 20% by weight based on the total amount of compounds.
% by weight of resorcinols may be used.

If the amount of resorcinol-formaldehyde resin initial condensate or resorcinol used is less than the above-mentioned amount, the anti-shrinkage effect will be insufficient and it will be unsuitable for the present invention, and if it exceeds the above-mentioned range, large cavities will be formed in the UF foam, resulting in a uniform UF. It becomes difficult to obtain a foam, and at the same time, it is disadvantageous in terms of cost.

EXAMPLES The present invention will be explained in detail with reference to examples below, but the present invention is not limited to the following examples.
In the following description, all parts and percentages are based on weight unless otherwise specified.

Example 1 Urea formaldehyde resin initial condensate (trade name Euroform R-101, Mitsui Toatsu Chemical Co., Ltd.)
) was concentrated under reduced pressure to obtain a urea formaldehyde resin condensate for foam production with a solid content of 72% (hereinafter abbreviated as urea resin A).

After adding 20 parts of ethyl alcohol to 100 parts by weight of resorcinol, it was mixed with potassium hydroxide in mm ²
After adjusting the temperature of
A resorcinol-formaldehyde resin initial condensate having a viscosity of 500 centipoise at °C and a solid content of 70% was obtained.

To 80 parts of urea resin A, 20 parts of the above resorcinol formaldehyde resin initial condensate, 2 parts of sodium dodecylbenzenesulfonate, 40 parts of trichloromonofluoromethane, and 2 parts of 60% phosphoric acid were added and mixed and left at room temperature to produce. Immediately after, a UF foam with a density of 14.1 Kg/m ³ was obtained. This UF foam dried in one day at room temperature and had a density of 11.5 Kg/m ³ after drying. The shrinkage rate was 1.5%.

The shrinkage rate was determined by cutting out the foam immediately after production into a cube of 30 cm on a side, leaving it at room temperature for one month, measuring the length of each side, measuring the shrinkage rate, and calculating the average value. The same applies to the following examples.

Example 2 A UF foam having a density of 34.2 kg/m ³ immediately after production was obtained in the same manner as in Example 1 except that the amount of trichloromonofluoromethane used in Example 1 was changed to 20 parts. This foam had an air-dried density of 25.1 Kg/m ³ and a shrinkage rate of 0.6%.

Example 3 In the same manner as in Example 1, a resorcinol resin initial condensate was prepared from the following raw materials, and 90 parts of 5-methylresorcinol, 10 parts of resorcinol, 15 parts of paraformaldehyde, and 10 parts were mixed with 90 parts of urea resin A. . Sodium alkyl phenyl ether disulfonate (trade name manufactured by Nippon Nyukazai Co., Ltd.) was added to the above mixture.
2 parts of NewcoL271A), 40 parts of trichloromonofluoromethane, and 2 parts of 60% phosphoric acid were added and mixed to obtain a UF foam with a density of 19.0 Kg/m ³ immediately after production. The air-dry specific gravity of this foam is 13.0Kg/ ^m3 , and the shrinkage rate is
It was 1.0%.

Example 4 To 80 parts of urea resin A, commercially available resorcinol formaldehyde resin initial condensate (trade name
DFK resin #8000, solid content 65%, manufactured by Nagoya Yuka Co., Ltd.)
20 parts of sodium alkyl diphenyl ether disulfonate, the same as used in Example 3, 40 parts of trichloromonofluoromethane and 2 parts of 60% phosphoric acid to form a UF foam with a density of 19.1 Kg/m ³ immediately after production. I got it. The air dry density of this UF foam is 12.9Kg/ ^m3
The shrinkage rate was 0.9%.

Example 5 Immediately after production in the same manner as in Example 1 except that 6 parts of resorcinol formaldehyde resin initial condensate was used for 94 parts of urea resin A.
A UF foam with a density of 21.6 Kg/m ³ was obtained. This UF
The foam dried in one day at room temperature and had a density of 15.1 Kg/m ³ after drying. The shrinkage rate was 1.9%.

Example 6 80 parts of urea formaldehyde resin initial condensate (trade name Euroform R101, solid content 68%, manufactured by Mitsui Toatsu Chemical Co., Ltd.), 20 parts of the resorcinol formaldehyde resin initial condensate used in Example 1 and 100 parts of water were mixed to prepare a resin liquid. 85% phosphoric acid 13.4 parts, sodium dodecylbenzenesulfonate 8.3 parts, stabilizer 3.2 parts, and total hardness 200PPM
A curing agent liquid was obtained by mixing 963.8 parts of water (calculated as CaCO ₃ ).

The obtained hardening agent liquid was made foamy by blowing air into it using a foaming gun manufactured by British Industrial Plastics Limited, and then the same volume of resin liquid as the hardening agent liquid was sprayed into it using a spray nozzle. Spray and mix to achieve a density of 42Kg/ ^m3 .
Obtained UF form. The air dry density of this foam is
The weight was 12.5Kg/m ³ and the shrinkage rate was 0.8%.

Comparative Example 1 A UF foam was produced in the same manner as in Example 1, except that the use of the resorcinol resin was omitted. The obtained UF foam shrunk significantly immediately after production, and the density could not be measured immediately after production. Therefore, the shrinkage rate could not be measured using the same method as in Example 1, but from a comparison of the maximum height of the foam produced by foaming in a box-shaped container and the height of this foam after air-drying, it was estimated that approximately It was recognized that it was 10%.

The air-dried density was 26.4Kg/ ^m3 .

Claims (1)

[Claims] 1. In a urea resin foam obtained by mixing a curing agent with a urea formaldehyde resin initial condensate in the presence of a surfactant and curing it, a resorcinol formaldehyde resin initial condensate is added to the urea formaldehyde resin initial condensate. A modified urea resin foam characterized by being used in combination with.