JPS58184034A - Resin coated sand - Google Patents

Abstract

PURPOSE:To provide resin coated sand which prevents the generation of crack in a shell mold after charging of molten metal, has no mal-odor and retains an original collapsing property without decreasing by coating a refractory granular material for casting with a phenolic resin compounded with petroleum pitch. CONSTITUTION:0.5-40pts.wt. petroleum pitch is compounded with 100pts.wt. phenolic resin in the stage when the reaction of phenols and aldehydes initiates, during the reaction or when the reaction ends in the stage of producing a phenolic resin. The compounding is accomplished by a method of, for example, grinding and mixing both. A lubricant such as ethylene-bis stearamide is added to said mixture preferably at <=10pts.wt. in 100pts.wt. phenolic resin. The above- described phenolic resin compounded with the petroleum pitch is mixed with sand grains for casting preferably by a dry hot coating method, whereby the intended resin coated sand is obtained. For example, a novolak type phenolic resin is used for the above-described phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides zinc coated sand 1 for V-elmold.
This relates to two special lids and resin-coated sand that prevents cracks that occur during pouring into molds.

Conventionally, the molar ratio of phenols and aldehydes to 1 mole of phenol is generally 0.6 to 0.
Using hexamethylenetetramine as a curing agent for a novolac type phenolic resin reacted in the presence of an acidic catalyst at 9 mol, or in the presence of an alkaline catalyst with 1 to 3 mol of aldehyde per 1 mol I of phenol. A dry hot coating method is known in which the reacted solid resol type phenolic resin is mixed as it is with heated foundry sand grains to produce resin coated sand for shell molds to produce molds.

However, conventional phenolic resins generally have the disadvantage that cracks are likely to occur in the mold when pouring into the mold. This is thought to be due to the rapid thermal expansion of the coated sand due to the high heat during pouring. To solve this,
A method has been adopted in which a material with a cushioning effect is added to phenolic resin or coated sand to give the mold flexibility and to reduce the expansion rate of the mold to prevent the occurrence of cracks. Vinsol, bisphenol A, petroleum resin, rosin, and the like have conventionally been used as cushioning materials. All of these reduce the expansion rate of the mold and are effective to some extent in preventing cracks, but they also cause thermal decomposition and volatilization during pouring, producing a bad odor, or causing the mold to collapse after pouring. It had the disadvantage of being bad.

The present inventors have conducted extensive research to overcome these drawbacks, and as a result, the presence of petroleum pitch in resin-coated sand, in which refractory granules for foundry use are coated with phenolic resin, allows V- It has been found that this method prevents the occurrence of cracks in the L mold, has no bad odor, and does not reduce its collapsibility.

The petroleum pitch used in the present invention is a residue generated during petroleum refining, and is a mixture of various types containing aliphatic or aromatic hydrocarbons as a main component. These petroleum pitches preferably have a softening point (according to JIS K-2207) of 80 to
It has a temperature of 120°C.

The phenolic resin used in the present invention may be a novolac type resin, a resol type resin, or a mixture of a novolac type resin and a resol type resin.

Phenols used as raw materials for phenolic resin penetration include phenol, cresol, xylenol, etc., but resorcinol, catechol, hydroquinone,
Those containing aniline, urea, melamine, cashew nut shell oil, etc. can also be used. As the aldehyde, an aldehyde substance selected from formalin, paraformsoldehyde, trioxane, ayatoaldehyde, etc. is used.

Furthermore, in the case of novolak-type resins, the reaction catalyst between phenols and aldehydes is generally an acidic substance such as oxalic acid, hydrochloric acid, or sulfuric acid, and a metal salt of an organic acid; in the case of resol-type resins, it is generally a primary amine such as ammonia or ethylamine. ,
Secondary amines such as ethylenediamine and diethylamine, tertiary amines such as triethylamine, caustic soda,
One or more of alkali metal hydroxides such as caustic potassium, alkaline earth metal hydroxides such as calcium hydroxide, and magnesium hydroxide are selected and used.

The blending ratio of the petroleum pips of the present invention to the phenolic resin is as follows:
The optimal range is 0.5 to 40 parts by weight per 100 parts by weight of the phenol resin. If the petroleum pitch is less than 0.5 parts by weight, the effect of preventing cracks in the shell mold will be poor, and if it exceeds 40 m1t part, the strength of the shell mold will decrease.

Petroleum pitch is blended at any time during the production of the phenol resin, at the start of the reaction between phenols and aldehydes, during the reaction, or after the reaction has ended. Alternatively, there is a method of pulverizing and mixing the phenol resin and petroleum pitch after production of the phenol resin, or a method of melt-mixing using a kneader such as an extruder.

Furthermore, petroleum pitch can also be blended during the manufacturing process of resin coated sand. The timing of addition during the manufacturing process of the resin coated sand depends on whether the phenol resin is added 1 or after the addition, or simultaneously. In addition, petroleum pitch may be blended separately or by being dispersed or dissolved in a medium. Regardless of the blending method, the rapid thermal expansion coefficient of the shell mold manufactured from the resulting resin-coated sand is significantly reduced.

As the lubricant II for carrying out the preferred embodiment of the present invention, conventional lubricants can be used, but ethylene bisstearamide, oxystearamide, stearamide, and methylolstearamide are preferred. In addition, this lubricant is used before and during the reaction during the production of phenolic resin.
A phenol resin containing a lubricant can be produced even if it is added either at the time of completion of the reaction or at the end of the reaction. The internal value of the lubricant is less than 10m compared to the phenolic resin 10011 part number.

Furthermore, if aromatic monocarboxylic acids and derivatives thereof are added to the phenolic resin of the present invention, in addition to the effects of the present invention, the curing of the resin during casting molding is accelerated.

The method for producing the coated sand employed in the present invention may be any of the dry hot coating method, semi-hot coating method, cold coating method, and powder solvent method, but the present invention is more preferred. Dry hot coating method is recommended.

The present invention will be explained below using Examples (2). However, the present invention is not limited to these Examples.

In addition, "1s" and "l'*J" described in each Example and Comparative Example all indicate "1 and lid part" and "weight 4[.

Production Example 1 In a reaction pot equipped with a cooler and a stirrer, add 1000 parts of phenol, 650 parts of formalin, 1 part of oxalic acid, and 1 part of oxalic acid.
I prepared 01B. The temperature was gradually raised and after the temperature reached 96°C, after a reflux reaction for 120 minutes, 10 parts of methylene bisstearamide and petroleum pitch (softening point 108°C) were mixed.
) 100 parts were added. After the mixture was mixed and dispersed, a dehydration reaction was performed under vacuum and the mixture was taken out of the pot. A novolac type phenolic resin containing a lubricant was obtained.

Production@2 A novolac type phenolic resin containing a lubricant was obtained under the same production conditions as Production Example 1 except that 200 parts of petroleum pitch was used.

Production Example 3 A reaction vessel equipped with a cooler and a stirrer was prepared, and 1000 parts of phenol, 1795 parts of 37-liter formalin, and then 2B
60 parts of 96 ammonia water 16 aqueous solution of 600% sodium hydroxide were charged. The temperature gradually rises to 96℃
After refluxing for 30 minutes, 40 parts of ethylene bisstearamide was added, followed by 110 parts of -2 petroleum Pif (softening point 95°C).

After the mixture was mixed and dispersed, a dehydration reaction was carried out under vacuum, and the mixture was taken out of the pot and rapidly cooled. A solid resol type phenolic resin containing a lubricant was obtained.

Production Example 4 A resol-type phenolic resin containing a lubricant was obtained under the same production conditions as Production Example 3 except that petroleum pitch was changed to 165 parts.

Production Example 5 A reaction vessel equipped with a cooler and a stirrer was prepared, and 1000 parts of phenol, 650 parts of 3-fluoride formalin, and then 1 part of oxalic acid were added.
I prepared 0 copies. The temperature was gradually raised, and after the temperature reached 96° C., reflux reaction was carried out for 30 minutes, and then 10 parts of methylene bisstearamide was added. After the mixture was mixed and dispersed, a dehydration reaction was performed under vacuum and the lid was removed. A novolac type phenolic resin containing a lubricant was obtained.

Production Example 6 A reaction vessel with a cooler and a stirrer was prepared, and 1000 parts of phenol, 1795 parts of 3796 formalin, and then 2
160 parts of 8g6 ammonia water and 60 parts of 5096 sodium hydroxide aqueous solution were added.

The temperature was gradually raised, and after the temperature reached 96°C, a reflux reaction was carried out for 30 minutes, and then methylene bisstearamide 40
1B was added, a dehydration reaction was carried out under vacuum, and the solution was taken out of the pot and rapidly cooled. A solid resol type phenol resin tloo portion containing a lubricant was obtained.

'#Example 1 Sanei No. 6 silica sand 7000 heated to 4 degrees 130-140℃
After adding 140 parts of the novolak type phenolic resin obtained in Production Example 1,
The mixture was kneaded for 0 seconds.

Next, 21 parts of hexamethylenetetramine dissolved in 105 parts of water was added and kneaded until the coated sand disintegrated. Furthermore, 7 parts of calcium stearate was added, and 3 parts of calcium stearate were added.
After mixing for 0 seconds, the sand was removed and aeration was performed to obtain coated sand.

Example 2 Production Example 24: Production conditions were the same as in Example 1 except that the novolac type phenolic resin obtained in Example 2 was used (a coated sand was obtained).

Example 3 Sanei No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 140 parts of the obtained solid resol type phenolic resin to a Whirl mixer, 140 parts of the obtained solid resol type phenolic resin were added and kneaded for 40 seconds. Then, 105 parts of cooling water was added, and the coated sand collapsed. I kneaded it until it was mixed.

Furthermore, 7 parts of calcium stearate was added, mixed for 30 seconds, sand was removed, and aeration was performed to obtain coated sand. Example 4 Except for using the solid resol type phenolic resin obtained in Production Example 4. A coated sand was obtained under the same manufacturing conditions as in Example 3.

Example 5 Cubic No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 130 parts of the novolak type phenolic resin obtained in Production Example 5,
Kneaded for seconds. At 1', 13 parts of petroleum pitch was added and kneaded for 20 seconds. hexamethylenetetramine 21s
was dissolved in 105 parts of water and added, and the mixture was kneaded until the coated sand disintegrated. Tsuide Calcium Stearate 7
After mixing for 309 minutes, the sand was removed and aerated to obtain coated sand.

Comparative Example 1 Cubic No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 140 parts of the novolak type phenolic resin obtained in Production Example 5 to a Whirl mixer, 40 parts of
Kneaded for seconds. Next, 21 parts of hexamethylenetetramine dissolved in 105 parts of water was added and kneaded until the coated sand disintegrated. In addition, calcium stearate 7
30 seconds, and the sand was removed and aerated to obtain coated sand.

Comparative Example 2 Cubic No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 140 parts of the solid reso-lotus type phenolic resin obtained in Production Example 6, 140 parts of the solid reso-lotus type phenolic resin were added and kneaded for 40 seconds. Then, 105 parts of cooling water was added and the coated The mixture was kneaded until the sand crumbled.

Further, 7 parts of calcium stearate was added, mixed for 30 seconds, and aeration was performed to obtain coated sand.

Table 1 shows the characteristic values of each resin coated sand obtained in Example 1.2.3.4.5 and Comparative Example 1.2 and the collapsibility of the shell mold.

The test method is as follows.

Bending strength: According to JACT test method 5M-1.

Adhesion point: According to JACT test method.

Hot tensile strength: According to JACT test method 5M-10.

Rapid thermal expansion coefficient: Based on JACT test method 5M-7.

The measurement temperature was 1000°C.

Disintegrability Niresin coated sand 29/”
Pour into a 150% iron pipe and pre-fire at 250°C for 305 minutes. The pipe is coated with aluminum i and treated at 370°C for 3 hours.

After cooling, take out the pipe and A hook attack was applied using the Togeki test machine shown in Figure 1. Eh, take out the collapsed sand every time. Then, measure the amount of remaining sand and find that the amount of sand is 0. Calculate the number of strikes made.

In Figure 1, A is a sample, B represents a part of the hammer.

Part of the hammer is an arm that rotates around branch C. The fulcrum of a part of the hammer is installed at a height of 30 aa, and the part of the hammer is lifted horizontally and then allowed to fall naturally, and the fulcrum is used as the center to apply an equal force to the sample.

[Brief explanation of drawings] Figure 1 shows an impact tester for testing disintegration. A lotus]/pull, B is part of the hammer; C is the fulcrum where part of the hammer is attached.

Claims (6)

[Claims] (1) A resin-coated nand with one petroleum pitch present in coated sand coated with refractory granules for molds with phenolic resin. (2) The resin-coated nanodos according to claim 1, wherein the amount of petroleum pitch blended is 03 to 40 parts by weight based on 100 parts by weight of the phenol powder. (3) The resin coated sand according to claim 1, wherein the phenolic resin is a novolak type phenolic resin. (4) The resin-coated nanodo according to claim 1, wherein the phenolic resin is a resol type phenolic resin. (5) The resin coated sand according to claim 1, wherein the phenolic resin is a mixed resin of a novolak type phenolic resin and a resol type phenolic resin. (6) Claims 1, 113, 4, or 5 characterized in that the phenolic resin contains a lubricant.
Resin coated Nando as described in section.