JPS5825372B2 - Method for manufacturing urea resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a urea resin foam (hereinafter abbreviated as UF foam) that can be foamed even under severe conditions.

).

Aqueous solution of urea-formaldehyde initial condensate (hereinafter abbreviated as resin liquid).

), a curing agent, and a foaming agent (hereinafter abbreviated as curing liquid).

) is used as a raw material, brought into a foamed state by a mechanical method, mixed and cured to produce UF foam, which is generally well known.

UF foam has the characteristics of being inexpensive, hard to burn, can be foamed on-site, and has good water absorption properties, and is used as an energy-saving insulation material for homes, agricultural materials, and coal mines. Demand is expected to increase for use as fillers and other applications.

One of the problems encountered when producing UF' foam according to known methods is the resin liquid and curing liquid (hereinafter abbreviated as stock solution).

The quality of the obtained UF foam varies considerably due to the influence of disturbance factors such as temperature, curing agent, foaming agent concentration, and water quality of dilution water.

That is, if the temperature of the stock solution is too low, if the concentration of the curing agent or foaming agent is too high or low, or if the hardness of the dilution water is too high, the foaming power and curing rate will decrease.

The present inventor has found that even under the above harsh conditions, good UF
As a result of intensive research into methods for producing foam with good reproducibility, we decided to use alkyldiphenyl ether sulfonates instead of alkylbenzene sulfonates, higher alcohol sulfates, etc., which are commonly used as foaming agents. I achieved my goal.

In other words, this foaming agent has excellent foaming properties especially at low temperatures and is not easily affected by various disturbance factors.For example, when the stock solution temperature is 5°C or lower,
Even when the concentration of curing agent and foaming agent fluctuates widely, or when hard water such as coal mine water or river water is used, the foaming power remains extremely stable, and as a result, fluctuations in curing speed are avoided. The present invention was completed by discovering that a UF foam that is small and of good quality can be obtained with good reproducibility.

The present invention relates to a method for manufacturing UF foam by reacting a resin liquid and a curing liquid according to a known method, which is characterized in that an alkyl diphenyl ether sulfonic acid or a salt thereof is used as a foaming agent. It's a method.

In the past, a known method for manufacturing UF foam was to foam a resin liquid and then blow out a hardening liquid.
This method causes many problems such as clogging of the resin in the foaming gun, and the current method is to foam the curing liquid and then blow out the resin liquid.

For example, a UF foam having a uniform cell structure can be obtained by blowing air into the curing liquid to create fine bubbles and then blowing the resin liquid onto the bubbles.

Specifically, using a foaming gun for UF foam commercially available from Schalam Hemy, West Germany, BIP, UK, etc., the resin liquid is sprayed from a spray nozzle and mixed into the hardening liquid that has been foamed by blowing air. .

The obtained UF foam is usually cured by leaving it naturally.
dry.

In addition, using a gas such as nitrogen or carbon dioxide instead of air,
Of course, methods using various foaming agents are also possible.

The resin liquid is manufactured, for example, in the following manner.

Water is added to urea and formalin as needed, and the mixture is initially reacted at 80 to 95°C near neutrality.

When the reaction has progressed to a certain extent, the pH is adjusted and the reaction is continued, and at the end of the reaction, a small amount of urea is added to reduce unreacted formaldehyde.

Dilute with water as necessary to adjust solids content.

Note that modified products in which urea is partially replaced with melamine, phenol, etc. can also be used.

Further, as the curing liquid, an aqueous solution containing a curing agent, a foaming agent, and an auxiliary agent is used.

All known curing agents and auxiliaries can be used; examples of curing agents include phosphoric acid, sulfuric acid, acetic acid, p-)luenesulfonic acid, etc., or a mixture of two or more of them; Examples include hydrophilicity-imparting agents such as polyethylene glycol, polypropylene gelicol, and polyhinyl alcohol.

As the foaming agent, an alkyldiphenylny7)I/sulfonic acid or a salt thereof is used.

The alkyl group is a linear or branched one having 4 to 14 carbon atoms, and includes a mono- or poly-substituted alkyl group with a single alkyl group or two or more types of alkyl groups.

The number of sulfonic acid groups can be 1 to 4, but it is common to have one sulfonic acid group substituted on each of the two benzene rings.

Suitable salts are potassium, sodium, lithium, ammonium or calcium salts.

Specific examples include dodecyl diphenyl ether disulfonic acid and its salts, hexyl diphenyl ether disulfonic acid and its salts, diundecyl diphenyl ether disulfonic acid and its salts, etc., which are easily and inexpensively available and industrially useful. is a mixture of mono- or polysubstituted diphenyl ether disulfonic acid with linear and branched alkyl groups having 4 to 14 carbon atoms (
6 or its sodium salt, hereinafter abbreviated as ADPES;
Potassium and calcium salts.

These foaming agents can be used alone or as a mixture of two or more, and commonly used foaming agents such as alkylbenzenesulfonates, alkylnaphthalenesulfonates, higher alcohol sulfates, and alkylphenol sulfates Ester salt, alkyl sulfate ester salt,
It can also be used in combination with higher fatty acid salts and the like.

The foaming agent of the present invention has excellent foaming properties, especially at low temperatures, compared to the above-mentioned commonly used foaming agents, and has a feature that the lower the temperature of the stock solution, the faster the curing speed of foam formation.

In addition to the temperature of the stock solution, the concentration of the foaming agent and the pH of the curing solution
Even if various factors such as dilution water hardness change, the effect on the curing rate is relatively small, and the quality of the resulting foam is therefore very good and stable.

Almost no changes over time due to long-term storage of the curing solution are observed.

The present inventor previously invented a method for producing UF foam with a slight formalin odor, which is characterized by containing urea or a substance having a phenolic hydroxyl group in the curing liquid.
This method had the drawback of slow curing speed, especially at low temperatures, but this drawback could be overcome by use of the foaming agent of the present invention.

According to the present invention, a UF foam of stable quality can be obtained even under severe conditions, and construction can be carried out during extremely cold periods or by diluting water in underground mines, so it is especially suitable for filling construction for coal mines and outdoor insulation construction in cold regions. It brings about remarkable effects in applications such as

The method of the present invention will be explained below with reference to Examples.

Parts in the examples represent parts by weight.

The gel time for foaming is the time required for the foam to not adhere to the finger when touched with the finger, and the cell condition is indicated in the order of ◎, ○, Δ, and × from the best.

Example 1 While stirring and mixing 36.7 parts of urea, 75.4 parts of 37% formalin, 30 parts of tap water, and 0.3 parts of 24% aqueous ammonia, 40% formic acid was reacted at around 90°C for about 1 hour. In addition, the pH was adjusted to 4 to 5, and after further reaction for about 1 hour, the pH was adjusted to 8 with 20% caustic soda.

After adding 4.2 parts of urea and reacting at 65° C. for 30 minutes, the mixture was immediately cooled, and the resulting reaction product was diluted with the same volume of tap water to prepare a resin liquid.

Curing agent 85% phosphoric acid 13.4 parts, foaming agent ADPES sodium salt 8.3 parts, auxiliary agent 3.2 parts and tap water 75.1 parts
A hardening solution was prepared by stirring and mixing the two parts and diluting the mixture with dilution water to a volume ratio of 10 times.

Using the above-mentioned resin liquid and curing liquid at a volume ratio of 1:10, air was blown into the resin liquid to foam the resin liquid, and the resin liquid was cured and dried to form a foam according to the method described in the main text of the present specification.

The gel time, foam density and cell condition for forming the foam are shown in Table 1, and a good UF foam was obtained.

Examples 2 to 10 The method of Example 1 was carried out by changing the foaming agent concentration, phosphoric acid concentration, dilution water hardness, and stock solution temperature in the curing liquid, and adding urea to the curing liquid as necessary. Table 1 shows the results.
Shown below.

Comparative Examples 1 to 10 In Examples 1 to 10, the foaming agent was changed to sodium alkylbenzenesulfonate, and the other conditions were carried out in accordance with Examples 1 to 10. The results are shown in Table 2, Comparative Examples 1 to 1.
0.

Claims (1)

[Claims] 1. In a method for producing a urea resin foam by reacting an aqueous solution of a urea-formaldehyde initial condensate with an aqueous solution containing a curing agent and a foaming agent, an alkyl diphenyl ether sulfonic acid or a salt thereof is used as the foaming agent. A method for producing a urea resin foam.