JPS59118243A - Composition for binding molding sand - Google Patents

Abstract

PURPOSE:To provide a titled compsn. with which a casting mold having high strength and excellent collapsing property can be formed by composing the same of a copolymer of a compd. contg. a benzene ring in the side chain of a linear molecule, a compd. contg. an epoxy functional group, and a silane compd., etc., and a hardener which is inactive at an ordinary temp. CONSTITUTION:A compsn. for binding molding sand consists of a copolymer of the compd. expressed by the general formula I (wherein R1 is a hydrogen atom or methyl group, R2 is a hydrogen atom or org. functional group), the compd. expressed by the general formula II (wherein R3 is a hydrogen atom or methyl group, R4 is an org. functional group having >=1 epoxy group), and a silane compd. having >=1 unsatd. group and/or a titanate compd. having >=1 unsatd. group and a hardener which is inactive at an ordinary temp. A casting mold and core for a shell mold having high heat resistance and collapsing property is obtainable from said compd. Isopropenyl benzene, etc. are used as the compd. of the above-mentioned formula I , and glycidyl methacrylate, etc. as the compd. of the formula II. Dicyandiamide, etc. are suitable as the hardener.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a foundry sand caking composition used for manufacturing molds or cores.

Regarding conventional casting molds and cores, the shell molding method using resin-coated sand with a phenol resin binder has been widely used as a molding method regardless of the type of alloy. In particular, cores are mostly manufactured by the shell molding method and are widely used because of its excellent productivity and dimensional accuracy.

However, when used for cast irons, especially cores, of low-melting light metal castings such as aluminum alloys, a portion of the phenolic resin undergoes a thermal change due to the heat of the molten metal, changing into an extremely strong graphite structure, resulting in The residual strength is extremely good, and after casting,
Each casting is heated at a high temperature of approximately 500°C for a long period of 5 to 10 hours to burn and discharge the residual graphite-structured binder, which consumes a large amount of energy. It has the disadvantage of requiring the consumption of For this reason, there has been a desire for a highly collapsible mold material for shell molding that easily undergoes thermal decomposition in the heat of the molten metal.

On the other hand, based on the results of research showing that the superior heat resistance of phenolic resins is attributable to benzene rings, searches are underway for modified phenolic resins or new resins with as few benzene rings as possible, but aluminum alloys If the binder is a resin that easily undergoes thermal decomposition due to the heat of the molten metal, the strong electric current (heat resistance) during baking molding of the @ mold or core will be insufficient and sufficient molding will not be possible. Although molding is possible when the amount of resin is increased in order to ensure sufficient stability, the amount of pyrolysis gas generated during pouring becomes large, increasing the occurrence of gas defects in the casting. Currently, no agent has been developed.

As a result of detailed investigation of the transition of phenolic resin to a graphitized structure, the present inventors found that if the benzene ring is included in the side chain of the linear molecule, the heat resistance will not be so low, and the graphitized structure after pouring will be reduced. We came to the conclusion that this is unlikely to occur, and as a result of extensive research, we were able to achieve the present invention.

That is, the present invention provides the following general formula [ID and [■] 1 Mechanical functional groups, such as Nagayari 1L alkyl group, human.

xyl group, acyl group, acyloxy group, alkoxy group, nitrile group, allyl group, substituted allyl group, propargyl group, allyloxy group, propargyloxy group, X is 0 or 1-
(representing an integer up to 5); and a monomer represented by 4C, in which R8 is a hydrogen atom or a methyl group, and R2 is an organic functional group having one or more epoxy groups; This invention relates to a foundry sand caking composition comprising a copolymer with a silane compound having one or more unsaturated groups and/or a titanate compound having one or more unsaturated groups, and a curing agent that is inactive at room temperature. be. Incidentally, the molecular weight of R2 is preferably up to the 500th position, and if it is more than this, the reaction becomes slow, which is not preferable.

Compounds of the general formula [ID used in the present invention include, for example, isopropenylbenzene, 0-isopropenyltoluene, m-ia7'robenyltoluene, p-isopropenyltoluene, isopropenylxylene, o-impropenylphenol, p-(sobropenylphenol, 2
-(Sobrobenyl-5-'f-ruphenol, 5-(So7
'Robenyl-2-methylphenol, 0-isopropenylbenzoic acid, p-isopropenylbenzoic acid, 2-impropenyl-5-methylbenzoic acid, 5-isopropenyl-2-methylbenzoic acid, styrene, etc. There is.

Examples of the compound of general formula [■] used in the present invention include glycidyl methacrylate, glycidyl acrylate, and allyl glycidyl ether (4).

Examples of the silane compound having one or more unsaturated groups used in the present invention include vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, and r-methacryloxypropyltrimethoxysilane.

Further, examples of the titanate compound having one or more unsaturated groups include isopropyl dimethacrylylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, and the like.

The composition ratio of the copolymer of these compounds is 10 to 88 mol% of the compound of the general formula [ID, 10 to 88 mol% of the compound of the general formula CI[), and 0% of the silane compound and titanate compound. It is preferably .5 to 20 mol%.

When the compound of general formula [ID is less than 10 mol% and when the compound of general formula If the amount of the compound of the general formula (I) exceeds 88 mol % or if the amount of the compound of the general formula [■] is less than 10 mol %, the current strength of the resin-coated sand decreases, which is not preferable. Furthermore, if the silane compound and/or titanate compound is less than 0.5 mol%, adhesive strength between the sand and the caking composition cannot be obtained, and when a core is made, the strength of the core is low. If it exceeds mol%, the strength of the caking composition itself will be lost, and the strength of the core will be low, which is preferable.

The molecular weight of the copolymer is preferably 700 or more and several tens of thousands of 1, and if it exceeds 100,000, it becomes rubbery and is not preferred.

If it is less than 700, the strength when molded into a core will be low.

A copolymer with a compound of the previous n13 general formula [I'3 and [■], a silane compound having one or more unsaturated groups, and/or a titanate compound having one or more unsaturated groups is generally known. It can be easily obtained by various polymerization techniques such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk radical polymerization. The generated polymer was measured for residual reed mass,
By measuring the epoxy equivalent, it is possible to determine the storage capacity of the tablet,
Usually available for high income homes of 95% or more.

In the present invention, the curing agent that is inactive at room temperature and used together with the above copolymer is a curing agent that does not react with the epoxy group-containing copolymer at room temperature but reacts in a short time when heated. , preferably a curing agent that can complete the reaction with the epoxy group within several minutes at a temperature of 150° C. or higher.

Examples of such curing agents include various dicyandiamide-based derivatives such as dicyandiamide, guanidine, and guanidine salts, cono-phosphoric acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, paraoxyamnesium, ric acid dihydrazide, and s-11 tylic acid dihydrazide. , organic acid hydrazides such as phenylaminopropionic acid hydrazide, cyanoethyl-substituted imidazole organic acid salts,
Imidazole derivatives such as azine-substituted imidazole, metal salts of imidazole, phthalic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride acid anhydrides such as metaphenylenediamine, aromatic diaminos such as diaminodiphenylsulfone, oxalic acid, tartaric acid, maleic acid, trimellitic acid, pyromellitic acid, l, 12
There are organic acids which contain 21 or more carboxyl groups in the molecule, such as -dodecanedicarboxylic acid, and one or more of these can be used. These hardening agents are
Its melting point is 60-800"C1 preferably 100-2
If the melting point is less than 60°C, the caking composition will melt and become sticky when mixed with sand, and will not fill the mold sufficiently, and if it is higher than 800°C, it will become solid. Therefore, even if it is put into a core mold, it will not melt or react, making it useless as a hardening agent.

Among the curing agents that are inactive at room temperature, in the present invention, various dicyandiamide derivatives, organic acid dihydrazides, imidazole derivatives, and organic acids are particularly preferred from the viewpoint of mold hardness and heat disintegration properties when heated. .

(8) Furthermore, the caking composition of the present invention may contain a curing accelerator in order to adjust the reaction rate between the epoxy group-containing copolymer and a curing agent that is inactive at room temperature during mold making. Also good,
For example, dimethylaminopheurea derivatives and the like are used as the curing accelerator. Imidazole derivatives and organic acid hydrazides, which also act as curing agents, are also effective as curing accelerators for dicyandiamide derivatives.

The amount of the caking composition of the present invention added to silica sand is usually 0.5 to 10% by weight, preferably 1.0% based on the amount of silica sand.
~3.0% by weight. If the amount added is less than 0.5% by weight, there is no effect of adding the caking composition.

In addition, if the amount exceeds 10% by weight, the thermal strength during mold manufacturing will increase, but this is not preferable since it causes problems such as a decrease in thermal disintegration during molten metal casting and an increase in casting defects due to an increase in the amount of gas generated. .

Next, the blending ratio of the epoxy group-containing copolymer and the curing agent is such that the amount of reactive active hydrogen groups in the curing agent is preferably 0.5 to 5.0 times the equivalent number of epoxy groups. is 1.0 to 8.0 times I. This blending ratio is 0.5 to 5
If the weight is outside the double equivalent range, the hot strength during mold production will be low, which is not preferable.

In addition, as the epoxy group-containing copolymer of the present invention, the above general formula [
In addition to the compounds of [I] and [■], a silane compound having one or more unsaturated groups, and a titanate compound having one or more unsaturated groups, monomers that can be copolymerized with these may be copolymerized. Needless to say, it can be done.

There are the following methods for producing resin-coated sand using the composition for caking tinsel of the present invention.

A method of adding and mixing the composition for caking brocade of the present invention to preheated silica sand, cooling the mixture, and melting the caking agent onto the surface of the silica sand. There is a method in which resin-coated sand is dissolved or dispersed in water or the like, mixed with preheated or unpreheated sand, and dried, but resin-coated sand with excellent properties can be obtained using either method. For workability and uniformity of mixing, fine powder of a binder composition, or a solution or dispersion thereof, is mixed with silica sand preheated to 120"C or higher, if necessary, and a hardening accelerator, and then heated to a temperature of 10"C.
A hot-melt method is preferred, in which the mixture is added and mixed after the temperature reaches 0''C or less.

The resin-coated sand obtained using the tinsel caking composition of the present invention thus obtained is poured into a mold heated to usually 150°C or higher, preferably 180 to 250"C, and heated for 80 seconds. It is possible to remove the mold after ~8 minutes and obtain a mold or core.

The present invention will be explained in detail below using Examples, Comparative Examples, and Test Examples.

Example 1 Production of epoxy group-containing copolymer Distilled water at 190 mA was added to a four-loaf flask equipped with a nitrogen inlet tube, a stirrer, an inlet for adding monomers, etc., and an 8 m condenser, and stirring was performed. Thereafter, 2.51 grams of sodium lauryl sulfonate was added, and while the inside of the reaction vessel was replaced with nitrogen, the mixture was thoroughly stirred and dissolved. After the sodium lauryl sulfonate was dissolved, the stirring was increased slightly to emulsify while gradually adding 47.59 g of isopropenylbenzene, 41.5 f of glycidyl methacrylate, and 52 g of r-methacryloxypropyltrimethoxysilane.

After sufficient emulsification, the temperature inside the reaction vessel was set at 50"C, and sodium bisulfite 0.052 and 5% dissolved in 50% water were added.
0.22 mt of potassium peroxide dissolved in water was added to initiate polymerization. The reaction was completely completed in about 8 hours.

The polymerization conversion rate after standing for one day was 97.8%.

Production of resin-coated sand No. 6 silica sand (l K9) preheated to 200°C was put into a speed mixer (manufactured by Enshu Tekko Co., Ltd.) while stirring, and when the sand temperature reached 180"C, the epoxy sand prepared above was added. The entire amount of the emulsion of the group-containing copolymer is added, and while it is melted and adhered to the surface of the sand grains, fine powder of dicyanamide (average particle size 4θμ) 202 and 8-8 as a hardening accelerator are added.
8v of (p-chlorophenyl)-1,1-dimethylurea was added when the sand temperature reached approximately 100°C.

The resin-coated sand was further stirred and mixed, and when blocking started, calcium stearate 82 was added as a wax to loosen the sand grains, and then taken out from the speed mixer to obtain resin-coated sand 1.

Examples 2 to 14 Examples 2 to 14 shown in Table 1 below in the same manner as Example 1
An epoxy group-containing copolymer was prepared, and using the curing agent and curing accelerator shown in Table 1, 18 types of resin-coated sand were produced using the same method as the method for producing resin-coated sand in Example 1.

The polymerization conversion of the copolymer in the example meeting was 83.7%,
All other copolymers had a polymerization conversion of 94% or more.

Comparative Example 1 No. 6 silica sand 4 K9 preheated to 200″C was put into a speed mixer while stirring, and when the sand temperature reached 170°C, commercially available novolak type phenolic resin 100S! (for 100 parts by weight of silica sand) After applying 2.5 parts by weight of 5P850D manufactured by Asahi Yokuzai Kogyo Co., Ltd. and fusing it to the surface of the sand grains, hexamethylenetetramine 152 (15 parts by weight per 100 parts by weight of the resin) was applied. A common water bath liquid 757 was added and the mixture was further stirred, and when the resin-coated sand started to cause blocking, calcium stearate 87 was added as a wax to loosen the sand grains, and then taken out from the speed mixer to prepare the sand grains of Comparative Example 1. Resin coated sand was obtained.

Comparative Example 2 In the same manner as Comparative Example 1, the phenolic resin 807 (2.0 (15) parts by weight per 100 parts by weight of silica sand) was added at 170°C, and hexamethylenetetramine 12
A resin-coated sand of Comparative Example 2 was obtained by adding 752 g of an aqueous solution in which 75 g of calcium stearate was dissolved and further adding 2.57 g of calcium stearate.

Test Example Hot Strength Test The resin-coated sand obtained in Examples 1 to 14 and Comparative Examples 1 and 2 was subjected to a hot strength test using a shell mold high temperature tensile tester. The firing conditions were 250°C x 60 seconds, and a test was conducted immediately after firing to determine the strength at elevated temperatures. The results obtained are shown in Table 2.

Heat disintegration test In this test, first, the resin-coated sand obtained in the Examples and Comparative Examples was poured into a mold preheated to 250°C, and a core was fired and molded. A core was prepared by inserting a core (diameter: 50 m x height: 80 mm) into the center of the core body (diameter: 50 m x height: 80 mm) to a depth of 10 mm. This baseboard will later serve as an outlet for the core sand.

As shown in Figure 2, the inner diameter is 100 am and the depth is 100 II.
After placing a core 8 in the center of a C02@ mold 4 having an IrR recess, 700°C AC2A aluminum alloy molten metal 5 was poured to about IQmi+ above the top of the core.

After solidification and cooling, the casting obtained by breaking the surrounding C02 castings is placed on the jig with the baseboard facing down, and the Hokari Seisakusho c stock)
Shock vibration was applied using a rotary tube test made by the company, and the amount of sand discharged from the discharge port was measured, and the thermal disintegration property was determined by comparing it to the original core mold part. The impact vibration time is 1 minute, 8 minutes, 5 minutes,
Cumulative measurements were taken over 10 minutes.

The obtained results are also listed in Table 2.

Table 2 (18) As mentioned above, when using the brocade caking composition of the present invention,
Even with the same amount of resin, the strength at high temperatures is high, and the thermal disintegration properties are extremely good in all cases.

In particular, in the case of the comparative example using phenolic resin, it is not expected that the reduction in the amount of resin will significantly improve the heat disintegration property, so the brocade caking composition of the present invention will greatly contribute to the energy saving of low melting point castings such as aluminum alloys. It is obvious that there is a contributing effect.

[Brief explanation of drawings]

FIG. 1 is a diagonal diagram of the core used in the thermal decay test, and FIG. 2 is an explanatory diagram of the thermal decay test. 1... Skirting board, 2... Core body, 8.
・・core, 4・CO□ mold, 5・・
・Aluminum alloy. Figure 1 Procedural amendment document March 9, 1980 1. Indication of the case 1988 Patent Application No. 2254.75 2. Name of the invention: Brocade binding composition 3. Person making the amendment Relationship with the case Patent applicant (399) Nissan Motor Co., Ltd. ■, page 10, lines 4-5 of the specification, "dimethylaminophenols" is corrected to "dimethylaminomethylphenols". 2. "Epoxy group-containing copolymer" in Table 1 of the same No. 15
Example 2 in the column. Example 8. Example 4. Example 5. Example] 0. Example 11. Example] 2° "γ-methacryloxypropylmethoxysilane" in Examples 13 and 14 is corrected to "γ-methacryloxypropyltrimethoxysilane", respectively.

Claims (1)

[Claims] 1. A compound represented by the following general formula (2) (in the formula, R□ is a hydrogen atom or a methyl group, and R2 represents a hydrogen atom or an organic functional group) and the following general formula: A compound represented by the formula %[: (in the formula, R8 is a hydrogen atom and a methyl group, and R2 is an organic functional group having one or more epoxy groups) and a silane having one or more unsaturated groups. 1. A composition for caking foundry sand, comprising a copolymer of a titanate compound and/or a titanate compound having one or more unsaturated groups, and a curing agent that is inactive at room temperature.