JPS63137936A - Production of foamed material - Google Patents

Abstract

PURPOSE:To stably add a solid additive over a long period and to prevent the troubles in apparatus, by mixing a liquid additive such as foaming agent and a solid additive such as inorganic powder in the form of a slurry having high concentration, compounding the slurry to a liquid thermosetting resin and extruding, foaming and curing the resin composition. CONSTITUTION:A liquid thermosetting resin is added with a liquid additive such as foaming agent, curing agent, etc., and a solid additive such as inorganic filler. In the above process, the solid additive is mixed with a small amount of the liquid resin, liquid additive or other liquid to form a slurry having high concentration, the slurry is added to the liquid resin and the whole mixture is extruded, foamed and cured. The resin is a thermosetting resin curable with an acid and the inorganic powder is powder of metal and/or metal compound capable of neutralizing an acid, preferably zinc, aluminum hydroxide, etc. The liquid used in the production of slurry is ethylene glycol, polyvinyl alcohol, etc., and the concentration of the slurry is 40-95wt%.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing a thermosetting resin foam.

[Conventional technology]

Foams of thermosetting resins such as phenol resins, epoxy resins, and urea resins are used for heat insulating panels and the like (Japanese Patent Publication No. 50-9826, JP-A No. 60-11520).

These foams are made by adding blowing agents, foam stabilizers, and thermosetting resin liquids.
It is obtained by adding and mixing a curing agent and a regulator added as necessary, such as an isocyanate compound, and then foam-molding the mixture. At this time, when an acid is used as a hardening agent, the acid remains in the foam after the foam is hardened and corrodes the steel plate serving as the face material, iron nails, etc. in post-processing. For the purpose of preventing these corrosions, a method of adding metal powder or inorganic powder such as calcium carbonate is known.

[Problem that the invention seeks to solve]

When adding inorganic powder such as metal powder continuously, it is common to add and disperse it in the resin liquid in advance.
With this method, due to the difference in specific gravity between the resin liquid and inorganic powder such as metal powder, if left for a long time, they will separate and settle, and the metering pump used for charging will be severely damaged, increasing repair costs. .

[Means for solving problems]

The present invention provides a method in which a foam is continuously formed by adding liquid additives such as a foam stabilizer, a foaming agent, and a hardening agent to a liquid thermosetting resin, and further adding an inorganic powder such as a metal powder. This is a method for producing a thermosetting resin foam in which a high concentration slurry of inorganic powder such as powder is added to a mixing section, mixed, and then foam-molded.

Examples of the thermosetting resin include phenol resin, epoxy resin, urea resin, and urethane resin, but phenol resin is preferable. The thermosetting resin has a viscosity of 500 to 20.
About OO0cps is good, preferably 1.0
00-15. OO0cps is used. For foaming operations, lower viscosity is preferable, but in general, lower viscosity materials have a higher water content, which adversely affects adhesion to steel plates.

The moisture content is preferably 20% by weight or less.

For example, such phenolic resins are produced by reacting phenols and formalin at a ratio of 1:1 to 1:3 in the presence of an alkali catalyst, neutralizing with acid, and then adjusting the viscosity appropriately by dehydration under reduced pressure. It can be obtained by

The liquid additive used in the present invention is one or more of a foam stabilizer, a foaming agent, a curing agent, and the like. Examples of foam stabilizers include silicone surfactants and nonionic surfactants. The preferred amount of foam stabilizer used is 0.5 to 1 per 100 parts by weight of resin.
It is 0 parts by weight.

Examples of the blowing agent include low-boiling aliphatic hydrocarbons or halides thereof, such as petroleum ether, n-hexane, methylene chloride, freons such as trichlorofluoromethane, and the like. As the curing agent, the curing agent used for each resin is used. In the case of phenol resins, organic acids such as henzenesulfonic acid, p-toluenesulfonic acid, and phenolsulfonic acid, and inorganic acids such as hydrochloric acid are used, and these may be used alone or in combination. In this case, the preferred amount of the curing agent used is 5 to 50 parts by weight of the acid based on 100 parts by weight of the phenol resin.

In the present invention, as other additives, in order to further improve the mechanical properties of the foam, for example, polyhydric alcohols such as ethylene glycol and glycerin, or, for example,
Nitrogen-containing compounds such as jetanolamine, triethanolamine, urea, and isocyanate compounds can also be mixed.

Solid additives used in the present invention include inorganic powders such as metal powders, metal compounds, and silicic acid compounds. Examples of metal powders include zinc powder and aluminum powder, and examples of inorganic powders include carbonates such as calcium carbonate and magnesium carbonate, and hydroxides such as aluminum hydroxide, barium hydroxide, lithium hydroxide, and calcium hydroxide. , alumina, oxides such as zinc oxide, other glass powders, clay, gypsum, talc, etc. These may be used alone or in combination, and powders whose surfaces are microencapsulated can also be used. When adding for the purpose of neutralizing acid,
Metals and/or metal compounds having the property of neutralizing acids are preferred, such as zinc, aluminum, calcium carbonate, magnesium carbonate, aluminum hydroxide, and the like.

The preferred amount used in this case varies depending on the property to be improved, but for example, in the case of a phenol resin for the purpose of neutralizing acids, it is preferable to add 2 to 20 parts by weight of zinc powder per 100 parts by weight of the resin.

The liquid for slurrying the inorganic powder such as the metal powder used in the present invention may be a liquid resin as a raw material or a liquid additive, but a liquid with relatively high viscosity is preferable. Preferred liquids include polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin, polyalcohols such as polyethylene glycol, polyvinyl alcohol, and polybutyl alcohol, nonionic surfactants, plasticizers such as dioctyl phthalate, and organic phosphate esters. These liquids may be used alone or in combination, and it is also possible to add curing accelerators such as resorcinol, m-cresol, and catechol to accelerate curing.

The concentration of metal powder or inorganic powder in the slurry is 40 to 95 wt%, preferably 50 to 80 wt%.
If the concentration is too low, separation of the slurry may occur, or a large amount of mother liquor may adversely affect the physical properties of the foam. Furthermore, if the concentration is too high, the viscosity of the slurry will increase, causing problems such as difficulty in supplying the slurry to the mixing and discharging section, and uneven dispersion of inorganic powder such as metal powder into the foam.

The foam according to the invention is produced as follows.

That is, a liquid additive such as a resin, a foaming agent, a foam stabilizer, a hardening agent, etc. and an inorganic powder slurry such as a metal powder are separately sent to a mixing and discharging section using a metering pump, and mixed and discharging is performed. 2. Before performing this mixing, the resin and liquid additives such as a foam stabilizer, foaming agent, and other additives are mixed in advance. Although it is optional to premix some of the components to be mixed and then mix the remaining components therein, it is preferable to mix the resin and curing agent immediately beforehand. Furthermore, it is contrary to the spirit of the present invention to pass an inorganic powder slurry such as metal powder through a transfer pump after mixing it. Therefore, when mixing is performed in two or more stages, the slurry is added to the final mixing section.

Gear pumps, diaphragm pumps, plunger pumps, etc. are examples of pumps that continuously and quantitatively pump resin, foaming agents, curing agents, etc., but gear pumps without pulsation,
A multiple diaphragm pump is preferred. The pump for metal powder or inorganic powder slurry may be any pump that can quantify high viscosity slurry, but gear pumps, snake pumps, etc. are preferable.

Examples of the mixer include a high-speed stirring type mixing head and a static mixer, but any device that can perform full-wave mixing may be used.

After the mixing is completed, the mixture is discharged and foam-molded by means such as pouring into a mold. An example of manufacturing a phenolic resin foam is to run a steel plate, continuously pour the mixed and discharged phenolic resin liquid into it, and pass it through a heating chamber at 50 to 100°C. A method of continuously obtaining a foam panel with a steel plate can be mentioned.

In this case, the steel plate used may be a galvanized iron plate or one whose surface is coated. As the paint, for example, acrylic resin paint, polyester resin paint, etc. are preferably used.

〔Example〕

The method of the present invention will be specifically explained below based on Examples and Comparative Examples.

Example A liquid prepared by adding 2 parts by weight of a foam stabilizer (L, -5340: manufactured by Nippon Unicar Co., Ltd.) to 100 parts by weight of Lusol (viscosity 1.000 cps), 20 parts by weight of a foaming agent (Freon 113), and 30 parts by weight of a hardening agent. Slurry (zinc concentration near 0 wt%) made by adding resol to part by weight (L%-p-toluenesulfonic acid aqueous solution manufactured by 66,7) and zinc powder (150 mesoyu) and kneading.5.
Using a metering pump, 7 parts by weight were thoroughly mixed by passing through a static mixer with 20 nφ and 25 elements, and then continuously poured into a metal form formed by rolls and heated to 90°C using a belt conveyor. A metal siding panel was obtained by foaming and curing in a continuous curing furnace. This operation was performed continuously for 2 hours, and after stopping at night, the same operation was performed again the next day for 2 hours continuously. The operation was smooth on both the first and second days, and the pH of the water immersed in the foam obtained from the start of operation until it was stopped the next day was measured and was in the range of 4.0 to 4.3.
It was found that the dispersibility of zinc powder was good.

Example 2 The same operation as in Example 1 was continued for one month and the operating conditions were observed. The operation was smooth and there were no abnormalities such as liquid leakage from the pump.

Comparative Example A liquid obtained by adding 2 parts by weight of a foam stabilizer (L-5340: manufactured by Nippon Unicar Co., Ltd.) and 4 parts by weight of zinc powder (1560 mesoyu) to 100 parts by weight of Luzol (viscosity 10.00 cps) and stirring well, and a foaming agent. Example 1: 20 parts by weight (Freon 113) and 30 parts by weight (66.7 wt% P-) luenesulfonic acid aqueous solution) were added using a metering pump.
A metal siding panel was obtained by carrying out the same operation as in Example 1, except that the sample was passed through the same static mixer.

The operation of the first pewter was smooth, but on the second day and month, the zinc powder in the resol settled and the shear pin of the pump broke at the start of operation. After repairs were made, the vehicle resumed operation and continued for two hours. The pH of the immersion water for the foam obtained in the first pewter was 4.1.
4.3, but the pH of the immersion water for the foam obtained on the second day was 4.8 to 3.0, which became lower in the latter half, indicating that the concentration of zinc powder was decreasing. understood.

Comparative Example 2 The same operations as in Comparative Example 2 were carried out continuously for one month, except that the liquid in Comparative Example 1 was used and a mixed solution of resol, foam stabilizer, and zinc powder was prepared and used before operation. The driving conditions were observed. The operation was smooth, but after 10 days, an abnormal noise was confirmed from the pump for the mixture of resol, foam stabilizer, and zinc powder, and after 20 days, it was discovered that the pump was leaking from the bearing.

〔Effect of the invention〕

According to the manufacturing method of the present invention, solid additives such as inorganic powders can be added stably for a long period of time, so fluctuations in the amount added, equipment failures, etc. can be significantly reduced.

Claims (3)

[Claims] (1) In a method of forming a foam by adding liquid additives such as blowing agents and hardening agents, and solid additives such as inorganic powder to liquid thermosetting resin, the solid additives are added to a small amount of liquid resin. Alternatively, a method for producing a foam, which comprises mixing with a liquid additive or other liquid to form a highly concentrated slurry, mixing the slurry into a resin and liquid additive mixing area, discharging the slurry, and foaming and hardening the slurry. (2) The method for producing a foam according to claim 1, wherein the resin is an acid-curable thermosetting resin. (3) The method for producing a foam according to claim 1 or 2, wherein the inorganic powder is a powder of a metal and/or a metal compound having the property of neutralizing acids.