JPS6139142B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an organic template caking material that hardens rapidly by aeration of carbon dioxide gas. Conventionally, the so-called CO ₂ method, which uses water glass as a caking material and hardens it by aeration of carbon dioxide gas, has been widely used. This CO ₂ method has several advantages, including that the binder is inexpensive, the mold can be removed immediately after aeration of carbon dioxide gas, resulting in high productivity, and the mixture does not react if stored in an airtight container, resulting in a long pot life. Has advantages. However, on the other hand, the water glass is sintered by the heat of the casting process, so sand removal is difficult in the case of cores, and collapsibility becomes a problem, which increases the number of man-hours and costs. It has become a drawback. Therefore, various methods have been tried to improve the disintegration properties of the CO ₂ method. The method of adding starch, fibers, etc. to water glass has some effect, but it inhibits the hardening of water glass and causes a decrease in cohesive strength, so it is necessary to satisfy both strength and disintegration properties sufficiently. I can't. Organic caking materials are advantageous in terms of disintegrability. The shell mold method, furan-no-bake method, etc. have good disintegration properties, but the shell mold method is a heat-curing type and has poor productivity. Further, the furanobake method has the disadvantage that productivity is poor because it takes a long time to reach a strength that can be removed from a mold, and that the pot life is short because the reaction proceeds at room temperature. Among the advantages of the CO ₂ method mentioned above, the high productivity and long pot life are due to the property that water glass quickly hardens only when gas is aerated. A hardening type is preferable. Recently, a cold box method has been developed that uses phenolic resin and isocyanate as a binder and cures at room temperature by blowing in amine gas. Although this cold box method generally satisfies productivity, pot life, and disintegration, it has the serious drawback of contaminating the working environment due to the strong toxicity of amine gas. The present invention was made for the purpose of solving the above-mentioned drawbacks of the prior art, and uses a phenol resin in which some or all of the hydroxyl groups have been converted to carboxylic acid ether as a binder component, and is cured with carbon dioxide gas, which is safe to handle. , which provides a mold caking material with high productivity, long water glass, and good disintegration properties. The present invention comprises (a) an alkali metal salt of a phenolic resin in which some or all of the hydroxyl groups have been converted into carboxylic acid ethers, (b) water, (c) a hydroxide and/or oxide of a polyvalent metal, and (d) the necessary This invention relates to a mold caking material for curing with carbon dioxide gas made of an organic solvent according to the requirements of the industry, and is based on the discovery that the caking strength can be improved by converting some or all of the hydroxyl groups of a phenolic resin into carboxylic acid ethers. . The reason for this has not been fully analyzed, but one reason is that calcium salts of phenolic hydroxyl groups are relatively water-soluble, whereas calcium salts of carboxylic acids are generally poorly soluble; This is thought to have led to an improvement in cohesion. The carboxylic acid etherified phenolic resin in which part or all of the hydroxyl groups used in the present invention are carboxylic etherified can be obtained by reacting the hydroxyl groups of a phenolic resin with a monohalogen derivative of an aliphatic carboxylic acid, and the hydroxyl groups of the phenolic resin are As it is,
Or react in the form of alkali phenolate.
Further, a carboxylic acid etherified phenol resin can also be obtained by a condensation reaction between a carboxylic acid etherified phenol monomer and an aldehyde. The phenolic resin to be reacted with the monohalogen derivative of aliphatic carboxylic acid may be of any type, such as novolac type or resol type, as long as it has a phenolic hydroxyl group. In addition, regarding synthetic raw materials, phenols include not only phenol but also cresol,
For xylenol, resorcinol, or aldehydes, formaldehyde, acetaldehyde, furfurame, etc. can be used. Monohalogen derivatives of aliphatic carboxylic acids include chloroacetic acid, chloromalonic acid, bromostearic acid, bromoacetic acid, α-chromiumpropionic acid,
Examples include B-chromium propionic acid, α-bromopropionic acid, B-bromopropionic acid, and the like. Carboxylic acid etherified phenol monomers include phenoxyacetic acid, and aldehydes include formaldehyde, acetaldehyde,
There are aldehydes such as furafural, and by performing a condensation reaction in the presence of a strong acid, a carboxylic acid etherified phenolic resin can be obtained. As described above, any resin in which the hydroxyl groups in the phenol resin are converted into carboxylic acid ether can be used in the present invention. The above resin is used by adding caustic alkali to convert the carboxyl group into an alkali metal salt and dissolving it in water.
The amount of caustic alkali is from 10 to 100 parts by weight of resin.
Add 100 parts by weight, preferably 20 to 80 parts by weight.
If it is too small, it will not become an aqueous solution, and if it is too large, the strength immediately after carbon dioxide gas ventilation will decrease. The reason for making an aqueous solution is that when carbon dioxide gas is aerated, polyvalent metals and resin Na
This is to obtain cohesive force by causing an ionic reaction with the salt; if the amount of water is small, the reaction will be difficult to occur, and if it is too large, the appearance of cohesive force will be delayed. Water is 100 to 500 parts by weight, preferably 150 to 500 parts by weight, based on 100 parts by weight of resin.
250 parts by weight are used. Polyvalent metal oxides and/or polyvalent metal oxides used in the present invention
Or as hydroxides, Ca, Mg, Ba, Zn, A
, Fe, etc., preferably Ca,
Mg, Ba, and economically more preferable is Ca hydroxide (slaked lime). These oxides or hydroxides are used in an amount of 30 to 300 parts by weight, preferably 50 to 150 parts by weight, per 100 parts by weight of the resin. The above-mentioned alkali metals, salts, water, and polyvalent metal oxides and/or hydroxides of the carboxylic acid etherified phenolic resin are the main components of the present invention, and when used as a mold caking material, preferably fireproof. An aqueous alkali metal solution of resin is added to the material particles and kneaded, and then an oxide and/or hydroxide of a polyvalent metal is added and kneaded to obtain a mold material. Caking material is 1 to 10% of refractory particles
If added, it will harden quickly after carbon dioxide gas ventilation, and will have the strength to be immediately removed from the mold. An organic solvent can be added to the caking material of the present invention, if necessary. The organic solvent has the effect of helping the resin alkali metal salt to dissolve in water, lowering the viscosity of the aqueous solution, and improving the strength immediately after carbon dioxide gas ventilation. As the organic solvent, lower monohydric alcohols such as methanol and ethanol, polyhydric alcohols, acetone, acetic acid ester, cellosolve, etc. can be used. The organic solvent is used in an amount of 1 to 100 parts by weight per 100 parts by weight of the resin, by adding it to the aqueous alkali metal solution of the resin or adding it during kneading. Glycerin, ethylene glycol, propylene glycol, etc. are used as the polyhydric alcohol. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Example 1. In a four-necked flask equipped with a condenser, thermometer, and stirrer, 940 g of phenol, 80% paraform, 225
g, 162 g of 37% formalin and 10 g of oxalic acid were reacted at 105°C for 3 hours, then dehydrated and concentrated until the softening point was 85.
A novolak-type phenolic resin (resin A) was obtained. Take 100g of resin A in another flask, add 100g of methanol to dissolve it, and prepare 9.5g of chromium acetate in advance.
Add a solution of 40 g of methanol and heat to 65℃.
I reacted with The generated hydrogen chloride was introduced into a 20% aqueous sodium hydroxide solution from the top of the cooling tube and absorbed. After 5 hours of reaction, methanol was removed under reduced pressure and 2
20% aqueous sodium hydroxide solution for 110g of the resin obtained by washing with water twice to remove unreacted chloroacetic acid.
75 g, methanol 10 g and glycerin 10 g were added and dissolved to form a binder. Example 2. Add and dissolve 200 g of a 20% aqueous sodium hydroxide solution to 100 g of the resin A of Example 1. To this, 139 g of chlormalonic acid dissolved in 200 g of water was gradually added, reacting at 80°C for 1 hour, and cooling to form a resinous precipitate. I got something. The resin was washed twice with hot water, and 50 g of water, 10 g of methanol, and 5 g of ethylene glycol were added to and dissolved in 102 g of the obtained resin to obtain a binder. Example 3. 940 g of phenol, 973 g of 37% formalin, and 60 g of 20% aqueous sodium hydroxide solution were put into a four-necked flask equipped with a condenser, thermometer, and stirrer.
The reaction was carried out at 60°C for 8 hours to obtain a 100p resol type phenolic resin at 30°C. To 110 g of this resin, 200 g of a 40% aqueous potassium hydroxide solution was added, and while 234 g of bromstearic acid dissolved in 200 g of water was gradually added thereto, the mixture was reacted at 80° C. for 1 hour and cooled to obtain a resinous precipitate. 102g of resin obtained by washing twice with hot water, 50g of water,
10 g of ethanol and 10 g of methylcellosolve were added and dissolved to form a binder. Example 4. 152 g of phenoxyacetic acid and 140 g of 37% formalin were put into a four-necked flask equipped with a cooling tube, thermometer, and stirring device, and while stirring, 50 g of concentrated sulfuric acid was added dropwise to react at 95°C for 5 hours. , cooled,
A resin precipitate was obtained. Resin 83 obtained by washing twice with hot water
80 g of a 20% aqueous sodium hydroxide solution, 10 g of methanol, and 10 g of glycerin were added and dissolved to form a binder. Control example: As an example in which carboxylic acid ether is not used, 200 g of 20% sodium hydroxide is added to 100 g of resin A of Example 1.
g, 20 g of methanol and 20 g of glycerin were added and dissolved to form a binder. The binders of Examples 1 to 4 and Comparative Example 1 were added to flattary silica sand in an amount such that the resin solid content was 1.5%, and after kneading for 1 minute, polyvalent metal oxides or hydroxides were added to the silica sand in an amount of 1.5%. % and kneaded for 1 minute to obtain mixed sand consisting of sand and caking material.
160 to 165 g of this mixed sand was compacted into a 50φ x 50 mm test piece, and carbon dioxide gas was aerated at 2 Kg/cm and 25/min for 20 seconds, and the compressive strength was measured immediately after aerating and after 24 hours. The results are shown in Table-1.

[Table] The caking material of the present invention exceeds the strength immediately after passing through the gas and the 24-hour strength as compared to the control example which is not subjected to carboxylic acid etherification. In other words, it was possible to make molds with good productivity and, since it was an organic caking material, with good disintegration.

Claims (1)

[Scope of Claims] 1. An alkali salt of phenol in which some or all of the hydroxyl groups are etherified with carboxylic acid, (b) water, (c) a hydroxide and/or oxide of a polyvalent metal (d), and as necessary Template caking material for carbon dioxide curing made of organic solvent as required. 2. The mold caking material for carbon dioxide curing according to claim 1, wherein the polyvalent metal hydroxide and/or oxide is an alkaline earth metal hydroxide and/or oxide. 3. The mold caking material for carbon dioxide curing according to claim 2, wherein the alkaline earth metal hydroxide is slaked lime. 4. The mold caking material for carbon dioxide curing according to claim 1, 2 or 3, wherein the organic solvent is a lower monohydric alcohol. 5. The mold caking material for carbon dioxide curing according to claim 1, 2 or 3, wherein the organic solvent is a polyhydric alcohol. 6. The mold caking material for carbon dioxide curing according to claim 5, wherein the polyhydric alcohol is glycerin.