JPH0573496B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a curing agent composition used when manufacturing a mold in a heat curing manufacturing method. More specifically, the present invention relates to a curing agent composition for heat-curing molds for curing a mixture of refractory granular aggregate and acid-curable resin. [Prior art and its problems] Conventionally, the method of manufacturing heat-curing molds involves coating fire-resistant granular aggregate with phenol novolak resin.
Approximately 300℃ using hexamethylenetetramine as a catalyst
There is a so-called shell molding method that heats and hardens the material nearby. This heat curing method is simple in terms of equipment;
Due to its advantages such as ease of use, it is currently the most commonly used method for manufacturing heat-hardening molds.
However, since the curing time is long and the curing temperature is high, there is a lot of distortion in the mold and the mold, necessitating deburring of the mold, and the dimensional accuracy is insufficient. Furthermore, the working environment is poor due to the high curing temperature, and the working environment is significantly contaminated by the odor of thermal decomposition of phenol resin and hexamethylenetetramine.
Significant improvements in these areas have been desired. In addition, at around 250℃, a mixture of fire-resistant granular aggregate mixed with an acid-curing resin such as phenol resol resin or phenol or urea/formalin-modified furan resin with a low furan content, and a curing catalyst such as ammonium chloride or oxalic acid. There is a so-called hot-boxing method in which the material is heated and cured. This method has a shorter curing time than the shell mode method, and is also improved in terms of temperature-induced distortion, dimensional accuracy, and thermal working environment, but it is desired to further shorten the curing time, improve the physical properties of the mold, and improve the working environment. There is. [Means for Solving the Problems] As a result of intensive research to solve the above problems, the present inventors found that a curing agent containing a specific sulfonic acid salt and a free sulfonic acid degrades other performances. The inventors have now completed the present invention by discovering that the curing speed of the mold can be significantly improved. That is, the present invention provides a curing agent composition for curing a mixture of a refractory granular aggregate and an acid-curable resin, which comprises a salt of a weak base and a lower aliphatic sulfonic acid or an aromatic sulfonic acid. and 5 to 50% by weight of free sulfonic acid. In the present invention, examples of lower aliphatic sulfonic acids include lower alkylsulfonic acids such as methanesulfonic acid, and examples of aromatic sulfonic acids include benzenesulfonic acid, phenolsulfonic acid, toluenesulfonic acid, and xylenesulfonic acid. etc. In addition, in the present invention, examples of weak bases include aluminum, copper, zinc,
Examples include metal salts such as iron. That is, the salt of a weak base and a lower aliphatic sulfonic acid or an aromatic sulfonic acid in the present invention is a salt obtained by reacting the above sulfonic acid with the above weak base, and particularly benzenesulfonic acid, phenolsulfonic acid, toluene Salts of at least one of sulfonic acid or xylene sulfonic acid and at least one of copper or iron are preferred. In the present invention, free sulfonic acid includes:
Examples include the aforementioned lower aliphatic sulfonic acids and aromatic sulfonic acids. Further, the amount of free sulfonic acid contained in the curing agent composition of the present invention is from 5 to
50% by weight, preferably 5-30% by weight. The curing agent composition of the present invention preferably contains 10 to 60% by weight of the above sulfonic acid salt, and
Preferably, the amount of solvent such as water or alcohol is 20 to 85% by weight. For a desirable curing agent composition and acid-curable resin system, the presence of the curing agent composition will not cause premature curing of the resin at a given operating temperature, but The resin must be rapidly and completely cured by reaching or exceeding a temperature of . Additionally, curing systems with relatively short visible times require repeated labor efforts by the foundry worker to mix the materials, or premature curing, i.e. placing the core material with sand into the mold or pattern to be formed. This results in waste of chemicals due to the necessity to dispose of material that has previously been cured. still,
The above-mentioned "pot life" means the time during which the curing agent composition can be kept mixed with the resin until a substantial portion of the polymerization reaction begins to occur. That is, if the amount of free sulfonic acid contained in the curing agent composition of the present invention, which is mainly composed of a salt of a weak base and a sulfonic acid, exceeds 50% by weight, the pot life will be reduced by the actual casting performance in recent years. The disadvantage is that the pot life is short compared to the acceptable pot life. The curing agent composition of the present invention is usually used as a solution of water or a solvent, but starch,
Saccharides and derivatives thereof such as cornstarch, glycol, and dextrin can also be contained. The acid-curable resin used in the present invention is mainly composed of furfuryl alcohol, a condensate of furfuryl alcohol and an aldehyde, a condensate of a phenol compound and an aldehyde alone, a mixture of at least one of them, or a co-condensed condensate. Examples of the phenol compound used include phetol, cresol, xylenol, resorcinol, methylenebisphenol, and catechol, with phenol, cresol, and xylenol being preferred. Furthermore, as a modifier, for example, urea or a urea/aldehyde condensate can be mixed or co-condensed with the acid-curable resin used in the present invention.
It is also possible to mix or co-condense at least one of conventionally known modifiers. Specific examples of conventionally known modifiers include coumaron/indene resin, petroleum resin, polyester,
Alkyd resin, polyvinyl alcohol, epoxy resin, ethylene vinyl acetate, polyvinyl acetate, polybutadiene, polyether,
Polymers and oligomers such as polyethyleneimine, polyvinyl chloride, polyacrylic acid ester, polyvinyl butyral, phenoxy resin, cellulose acetate, xylene resin, toluene resin, polyamide, styrene resin, polyvinyl formal, acrylic resin, urethane resin, nylon, and lignin. Natural products such as , lignin sulfonic acid, rosin, ester gum, vegetable water, bityumen, heavy oil, cashew nut shell liquid, vanillin, tannins, saccharides and their derivatives such as starch, cornstarch, glucose, dextrin, resorcin residue, cresol Residue, 2,2,4-trimethyl-4-
Reaction residues and by-products such as reaction by-products of (hydroxyphenyl)coumarone and isopropenylphenol, reaction by-products of terephthalic acid and ethylene glycol, polyhydric alcohols such as polyethylene glycol, and ketones such as acetone, cyclohexanone, and acetophenone. and condensates with aldehydes, amino or imino compounds such as dicyanamide, acrylamide, and thiourea, and their aldehyde condensates, aldehyde compounds such as furfural and glyoxal, and ester compounds such as isocyanuric acid esters and unsaturated fatty acid esters. etc. The modification rate of these modifiers is preferably 20% or less. Furthermore, in order to improve mold strength and ease of handling, a diluent may be mixed with the acid-curing resin within a range that does not adversely affect other properties.
The blending amount is preferably 20% by weight or less. Specific examples of diluents that can be used include aromatic hydrocarbons such as benzene and xylene, alcohols such as methanol, ethanol, and furfuryl alcohol, diethyl ether, anisole,
Ethers such as acetal, ketones such as acetone and methyl ethyl ketone, heterocyclic hydrocarbons such as tetrahydrofuran and dioxane, esters such as methyl acetate and ethyl acetate, polyhydric alcohols such as ethylene glycol and glycerin, 2
- Cellosolves such as methoxyethanol and 2-ethoxyethanol, cellosolve acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-phenoxyethyl acetate, and diethylene alcohol monoethyl Examples include carbitol acetates such as ether acetate. Furthermore, a silane coupling agent may be added for the purpose of further improving mold strength. Examples of the silane coupling agent include γ-(2-amine)aminopropylmethyldimethoxysilane,
Examples include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane. In order to manufacture the mold, silica sand mainly composed of quartz, zircon sand, chromite sand, olivine sand, etc. are used as a refractory granular aggregate together with the curing agent composition according to the present invention. It is not limited. [Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. Examples 1 to 10, Comparative Examples 1 to 4 100 parts by weight of Australian flattery silica sand,
A mixture of 0.45 parts by weight of a water-methanol (1:4 weight ratio) solution containing a weak base, a salt of sulfonic acid, and free sulfonic acid as shown in Table 1, and 1.5 parts by weight of urea-modified furan resin. was blown and filled with pressurized air into a 25 x 25 x 250 m/m mold preheated to 180°C, fired for 10 seconds to form a mold, and the mold bending strength was measured for 10 seconds after firing. The results are shown in Table-1.

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Claims (1)

[Scope of Claims] 1. A curing agent composition for curing a mixture of refractory granular aggregate and acid-curable resin, which comprises a salt of a weak base and a lower aliphatic sulfonic acid or an aromatic sulfonic acid. 1. A curing agent composition for heat-curing molds, which contains 5 to 50% by weight of free sulfonic acid. 2. A salt of a weak base and a lower aliphatic sulfonic acid or an aromatic sulfonic acid is a salt of at least one of benzenesulfonic acid, phenolsulfonic acid, toluenesulfonic acid, xylene sulfonic acid, or lower alkylsulfonic acid, and aluminum, copper, zinc, The curing agent composition according to claim 1, which is a salt with at least one type of iron. 3. The curing agent composition according to claim 1, wherein the content of free sulfonic acid is 5 to 30% by weight.