JPH0563258B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a gas-curable binder composition for molds. More specifically, the present invention involves adding and kneading an acid-curing resin and an oxidizing agent to refractory granules, forming the mixture into a mold, and then injecting gaseous or aerosol sulfur dioxide to produce a mold. This invention relates to an improved binder composition for use in cold boxes. [Prior Art] Conventionally, in order to manufacture molds at medium to high speeds, a cloning method has been widely used in which a mold is manufactured by heating and curing so-called coated sand in which granular refractories are coated with phenolic resin. However, in order to save energy during mold manufacturing, mold production speed, and improve the quality of molds and castings, the cold box mold manufacturing method, which hardens at room temperature using gaseous or aerosol substances, has been introduced as a mold manufacturing method that replaces the cloning method. There have been serious attempts to introduce it in the foundry industry. The cold box method involves curing acid-curing resins, typically furan-based resins, with sulfur dioxide using peroxide as an oxidizing agent, and curing polyols and polyisocyanates with an aerosol of tertiary amine as a catalyst. There is a urethane cold box that hardens as Among these, molds using urethane cold boxes have drawbacks such as poor disintegration of casting sand during casting production, and the tendency to cause casting defects such as sand trapping, scooping, pinholes, and soot defects. On the other hand, acid-curing cold boxes have been rapidly attracting attention in recent years as a method for solving the above-mentioned difficulties. [Problems to be Solved by the Invention] The present invention relates to a binder composition suitable for improving the mold productivity of acid-cured cold boxes. In other words, the acid-curing cold box mold saves energy during mold manufacturing, and the mold manufacturing speed is fast.
The quality of manufactured molds and castings are excellent, etc.
Although this method has many advantages over conventional cloning methods and urethane cold box methods, it also has issues that need to be improved. One of the problems is contamination of the mold manufacturing model, so-called staining. Staining refers to the liquid binder composition that is added to refractory granules and kneaded to coat them. During molding, the granules collide with each other during molding, and the granules are caused by hardening gas and fluids such as pressurized air for cleaning excess hardening gas. It is peeled off from the surface, adheres to the surface of the model, and when molds are repeatedly manufactured using the same model, this adhesion is repeated and a layer is formed as a stain. When this stain occurs, the smoothness of the model surface is impaired,
This may have an adverse effect on the quality of the mold, such as reducing the surface stability of the mold, or may impede productivity, such as requiring cleaning time to remove the stain. Furthermore, there may be a problem that the mold breaks due to insufficient strength of the mold. If the viscosity of the liquid binder is high, when the liquid binder is added to the refractory granules and kneaded, the liquid binder will not sufficiently cover the refractory granules. In addition, the fluidity of the liquid binder composition added to the refractory granules and coated by kneading is poor, and the mold cannot be filled sufficiently, resulting in insufficient strength when removing the mold from the mold and when transporting the mold. , the mold may break, reducing mold quality and productivity. Furthermore, when pouring the molten metal into the mold, the lack of strength of the mold causes plugging, sand trapping, etc., which reduces the quality and productivity of the casting. [Means for solving the problem] As a result of intensive research, the present inventors found that there is a close relationship between the furfuryl alcohol content in the binder and model contamination, and that the viscosity of the liquid binder However, the ability of the liquid binder to coat the refractory granules and the liquid binder composition that is added, kneaded, and coated to the refractory granules are closely related to the filling of the mold and the strength of the formed mold. This has led to the present invention. That is, the present invention is a gas-curing binder for producing molds using furfuryl alcohol as a main raw material and sulfur dioxide using peroxide as an oxidizing agent, and which is a gas-curing binder that is used in the production of molds using furfuryl alcohol as a main raw material and sulfur dioxide as an oxidizing agent. , or mixed or co-condensed with other components,
Mixed so that the furfuryl alcohol content in the binder is 30% or less, or the ratio of the furfuryl alcohol content in the binder raw material to the furfuryl alcohol content in the binder is 1:0.6 or less. or an acid-curing resin whose furfuryl alcohol content has been reduced by reaction, and at least one of the following (a) to (1).
The present invention provides a binder composition for molds, characterized in that it contains seeds. (a) General formula R ₁ −O−R ₂ ,

[Formula] or a compound represented by R ₁ - CHO (R ₁ and R ₂ are saturated or unsaturated aliphatic hydrocarbon groups having 1 to 8 carbon atoms). (b) General formula

A compound represented by the formula (R ₃ and R ₄ are aliphatic hydrocarbon groups or hydrogen atoms having 18 or less carbon atoms). (c) The substituent attached to the benzene ring is one or two of each of a methoxy group, an aldehyde group, or a nitro group.
or more than one type, or two or more types including a hydroxyl group, or an aromatic compound having two or more hydroxyl groups. (d) Aliphatic hydrocarbons having 5 to 12 carbon atoms. (e) Heterocyclic compounds having one or more oxygen atoms in the five- or six-membered ring, or compounds having one or more aldehyde groups in the furan ring. (f) A compound represented by the general formula R ₅ −COO−R ₆ (R ₅
and R6 is an aliphatic hydrocarbon group having up to 18 carbon atoms, provided that one of them can be a hydrogen atom). (g) General formula

A compound represented by the formula (R ₇ is an aliphatic hydrocarbon group having 8 or less carbon atoms). (h) General formula

Compound represented by [Formula] (R ₈ and R ₉ are saturated or unsaturated aliphatic hydrocarbon groups or hydrogen atoms having 8 or less carbon atoms) (i) General formula R ₁₀ -COO-R ₁₁ -OOC-R ₁₂ A compound represented by (R ₁₀ , R ₁₁ and R ₁₂ are aliphatic hydrocarbon groups having 6 or less carbon atoms). (j) A compound represented by the general formula _R13 -COO- _R14 -O- _R15 ( _R13 , _R14 and _R15 are aliphatic hydrocarbon groups having 4 or less carbon atoms). (k) General formula

〔Example〕

Examples will be described below to explain the present invention in more detail, but the scope of the present invention is not limited by these Examples. Examples 1 to 10 and Comparative Examples 1 to 5 Condensed furfuryl alcohol and formalin as shown in Table 1 [furfuryl alcohol content (A) in raw materials and furfuryl alcohol content in binder] The ratio of (B) (expressed as A/B)] was prepared, and further, in order to adjust the viscosity, a solvent, a diluent, a urea/formalin resin, etc. listed in Table 1 were added and mixed. Mix 1.2 parts by weight of these binders with silica sand and 0.5 parts by weight of methyl ethyl ketone peroxide, fill with kneaded sand using a horizontal split mold automatic molding machine at an air pressure of 3.0 kg/cm ² , and then inject sulfur dioxide gas. Then, excess gas was washed away with pressurized air, and a mold and a test piece for measuring bending strength were molded. Place a 1 cm square iron plate directly under the blow port where the mixed sand is injected with pressurized air, and repeat.
After molding the mold 200 times, the iron plate was removed and the amount of contaminants adhered to it was measured. The bending strength was measured 10 seconds after the mold was removed.

〔Effect of the invention〕

As is clear from this example, the present invention significantly reduces contamination adhering to the model, reduces the need for model cleaning during mold manufacturing work, and improves the strength of the mold, reducing the number of defective molds. As a result,
In addition to reducing mold downtime, improving productivity and greatly improving the quality of molds, complicated work has been eliminated, resulting in significant improvements in productivity and quality.

Claims (1)

[Scope of Claims] 1. A gas-curing binder for producing molds using furfuryl alcohol as a main raw material and sulfur dioxide using peroxide as an oxidizing agent, which is made by polycondensing furfuryl alcohol alone. Or, by mixing or co-condensing with other components, the content of furifuryl alcohol in the binder is reduced to 30% by weight or less, or by mixing or co-condensing with other components, An acid-curing resin whose furyl alcohol content is reduced by mixing or reaction so that the ratio of the furyl alcohol content is 1:0.6 or less, and at least one of the following (a) to (1). A mold binder composition comprising: (a) A compound represented by the general formula R ₁ -O-R ₂ , [Formula] or R ₁ -CHO (R ₁ and R ₂ are saturated or unsaturated aliphatic hydrocarbon groups having 1 to 8 carbon atoms). (b) A compound represented by the general formula [Formula] (R ₃ and R ₄ are an aliphatic hydrocarbon group having 18 or less carbon atoms or a hydrogen atom). (c) The substituent attached to the benzene ring is one or two of each of a methoxy group, an aldehyde group, or a nitro group.
or more than one type, or two or more types including a hydroxyl group, or an aromatic compound having two or more hydroxyl groups. (d) Aliphatic hydrocarbons having 5 to 12 carbon atoms. (e) Heterocyclic compounds having one or more oxygen atoms in the five- or six-membered ring, or compounds having one or more aldehyde groups in the furan ring. (f) A compound represented by the general formula R ₅ −COO−R ₆ (R ₅
and R ₆ is an aliphatic hydrocarbon group having up to 18 carbon atoms, provided that one of them can be a hydrogen atom). (g) A compound represented by the general formula [Formula] (R ₇ is an aliphatic hydrocarbon group having 8 or less carbon atoms). (h) Compound represented by the general formula [Formula] (R ₈ and R ₉ are saturated or unsaturated aliphatic hydrocarbon groups or hydrogen atoms having 8 or less carbon atoms) (i) General formula R ₁₀ -COO-R ₁₁ A compound represented by -OOC-R ₁₂ (R ₁₀ , R ₁₁ and R ₁₂ are aliphatic hydrocarbon groups having 6 or less carbon atoms). (j) A compound represented by the general formula _R13 -COO- _R14 -O- _R15 ( _R13 , _R14 and _R15 are aliphatic hydrocarbon groups having 4 or less carbon atoms). (k) A compound represented by the general formula [Formula] (R ₁₆ , R ₁₇ and R ₁₈ are aliphatic hydrocarbon or aromatic hydrocarbon groups having 6 or less carbon atoms). (1) Natural animal and vegetable oils and fats or natural resins. 2. The composition according to claim 1, wherein the amount of the compound or mixture of (a) to (1) is 0.5 to 50 parts by weight based on 100 parts by weight of the acid-curing resin. 3 Phenols, phenols/aldehyde polycondensates, urea, urea/aldehyde polycondensates, melamine, melamine/aldehyde polycondensates, ketones/
The composition according to claim 1, comprising a mixture or co-condensation of at least one of an aldehyde polycondensate, an aromatic hydrocarbon/aldehyde polycondensate, and a compound having one or more aldehyde groups in one molecule.