JPS5890346A - Coated sand for casting - Google Patents

Abstract

PURPOSE:To provide coated sand for castings having an improved blocking property by adding a thermoplastic or thermosetting resin to the sand coated with a binder consisting of melamine and a water soluble org. compd. thereby double coating the sand. CONSTITUTION:1-10pts. A binder consisting of alkylated methylol melamine or methylol melamine and a water soluble org. compd. having hydroxyl groups such as cane sugar is added to 100pts.wt. silica sand to coat the surfaces of the silica sand. Further, 0.1-10pts. a thermoplastic resin such as polystyrene or a thermosetting resin such as a phenolic resin is added to the coated sand to coat the outside surfaces thereof. By such double coating, the coated sand for molding of molds having an excellent blocking property without degrading bending strength and high temp. tensile strength is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION This Ji@ relates to coated sand for casting,
The present invention relates to coated sand for foundry molding, which requires a relatively low casting temperature, such as aluminum alloy. #Sulfur is coated with a binder consisting of alkylated mesolol or methane and a water S*organic compound having a hydroxyl group.
In addition, *ai is double acidified with a thermosetting resin 1 such as polystyrene or a copolymer mainly composed of styrene, or a thermosetting resin 11 such as a phenol resin or an unmalted polyester resin. Features: 11fl
It concerns $'.

Traditionally, the so-called shell molding method, in which sand coated with a phenolic resin binder is aged and bonfired, has been widely used. When used in cores such as aluminum alloy castings with low temperature, it is always difficult to remove # after casting due to insufficient collapsibility. After being treated for a long time, the cores with sharp edges are disintegrated using a knock-out machine and discharged as sand particles, but the labor and cost involved during this process is large.

The present authors have previously discovered that a binder consisting of methylolmelaline or alkylated metheromelaine and a water-soluble organic metal material having a hydroxyl group is an excellent binder for low-temperature casting. 1% request for discovering something @ 55-475
The application was filed as No. 80. However, this coated sand has a high f
If f114 is left or stored in a humid environment, it tends to cause the secondary prodskinder phenomenon in which the sands fuse together, which causes problems such as poor Jl rigidity and the formation of defects in complexly shaped cores.

A common method for preventing the blocking properties of sand particles and improving their fluidity is to add aS powder having lubricity. *For example, magnesium stearate (formulation engineering,
Calcicum, 'vgnesium, zinc or alkenium 2e) A salt of higher fatty acids having 12-20 carbon atoms (%ml@4a-saoyp publication).

Calcium stearate (41關1i849-48!2
(Report No. 1 1% 1@Report No. 50-10421), etc., it is true that the addition of such a fine powder having lubricity, that is, a lubricant, improves the blocking property.

On the other hand, it tends to reduce the strength of the cast iron, making it impractical.

As a result of intensive research, the present inventors have found that it is preferable to add 0.1 to 10 parts by weight of thermal im*w oil or thermosetting resin to 100 parts by weight of II# sand coated with the above-mentioned binder. o,
i-s weight SL-added, coat the outer surface and double value 6N
- is foundry sand with markedly improved blocking properties, and the addition of *AI material improves transverse rupture strength and high 1 tensile gt strength compared to uncoated sand. I discovered something. Thermal degree ima used in the present invention
Preferred examples of *m include polystyrene or copolymer 41111 containing 50 mol % or more of styrene (for example, styrene-maleic anhydride copolymer resin, styrene, acrylonitrile copolymer m polymer). Among the Kamemachi resins, the high aIj of the caster is found in the bolioid am or ketone tree layer.
One time is the first casting from all subjects of the present invention! Preferred examples of thermosetting resins that can only be obtained that are inferior to IK and are used for this purpose include phenolic resins and unsaturated polyester resins. If the amount of these thermosetting resins or thermosetting 1tgr is less than 0.1 parts by weight per 100 parts by weight of sand, the effect will be small, and if it is more than 10 parts by weight, the bird 1 strength will tend to decrease.

In superposition IjlI, the thermal degree ■ Resin, specifically polystyrene or a copolymer tree mainly composed of styrene *
A preferred method for controlling the surface area is to add a solution of a thermosetting resin dissolved in a volatile organic solvent to a # coated with a binder and evaporate the solvent without stirring, or to start polymerization directly on the resin. A method is adopted in which the mixture is added to sand mixed with a binder and heated while stirring to form a djjk polymer layer on the outer surface of the sand. In addition, as in the case of jllk adhesive resin, the preferred method for applying thermosetting resin is to use sand coated with thermosetting resin S liquid dissolved in a volatile organic solvent with a binder. #& finely, and make 41 shots without stirring, or add thermosetting resin powder or pellets to sand coated with binder and melt with heat while stirring to coat the outer surface El. is taken. When using this thermosetting resin, if a curing agent is required, an II-forming agent should be added to the thermosetting resin in advance, or
Or, the ammization rate alone with damage to the outer surface of a thermosetting resin can be improved by adding a hardening agent solution, or if a uniform surface is formed even without adding a hardening agent at all. The binder used in @honji@ which does not need to be added is a reaction product of mederolmefine or alkylated methylolmefine and water S*Arine compound, and here the water-soluble organic compound having a hydroxyl group is For example, single m class, ov:f@IA,
There are many types, including water-soluble cellulose conductors and polyhydric alcohols. In addition, a preferred specific surface coating method using the above-mentioned binder in the present invention is 1%@@55-475804
The method described in the specification is applied to neutralize methylolmelain or methylolmetuine and a water-soluble organic compound by dissolving and mixing them in water or other suitable common solvent, and then adding the mixture to sulfur sand. A method of removing the solvent while heating and mixing may be used.

In addition, in accordance with the '14 aspect of the present invention, even if a lubricant such as the above-mentioned calcium stearate is added at the time of coating the outer surface, it does not support adhesion.

The present invention will be explained below using practical examples. X, in the examples, parts are parts by weight and 1% is parts by weight.

Actual power example I L! 111 6o, 9% water filR7485, lfk
Methi Q-lumen 94 (Note x Chemical Swimmar M5D
11) 255 parts of t-S was added and stirred for 20 minutes to obtain an aqueous adhesive solution. fi for foundry furnace! 11! (Ruzhou Iron Works Speed Kenkina) K Bales operated with heated sand #PW
? For those who wish to do so, please preheat the tank and W111p blade to 40℃ or higher, and add separately to 180T:
l&L te mita sulfur 111 (ll1fH498#) 1
00iii was added, 8 m5 parts of the above-mentioned binder water was added, and the mixture was kneaded for 5 minutes to obtain sand coated with a binder.

While continuing to knead, add 0.1 part of PO to 5 parts of toluene K.
The dissolved m solution was added, and after mixing for 2 minutes, 0.1 part of calcium stearate was added, stirred for 50 seconds, and mixed to remove sand. The obtained double coated sand was Jxsx-4?10r
The bending strength (transverse rupture strength) of the molded test piece was constant according to the "Shell Seven-Door Powder * Fat Test Method". In addition, high-temperature tensile strength after processing at 280°C for 1 minute in accordance with JAOT test method 8M-IOK! It's #I
I4'i! (Tobuchi Keimitsu Kogyo Shaving 8501J1 testing machine) was tested in accordance with Sara K (JAOT) test method 0-4. l
Immediately after sand shaving and at 25°C.

After keeping temperature and humidity for 24 hours in an atmosphere of 4 parts %j1M, the protskindness was maintained constant. The results obtained are shown in Table 1.

Solid line fg2~S and comparison fR1~2 Instead of the polystyrene solution of Itsumugi s1, replace the polystyrene solution with V7G
,! Using a solution of J@#I'den Os dissolved in toluene and a solution of 1.0 part of polystyrene dissolved in toluene Kl for 15 s, the other conditions were the same as in Example 1, and the double wave ff1
l- was created. The physical properties were determined using the same method as in Example 1, and the results are also shown in Table 1. In addition, as a comparative example, a binder-covered ai prepared in the same manner as in Actual Example 1 was used.
At 1.

No double coating with polysprene (Comparative Example 1)
), shell coated with commercially available phenolic resin?
(Torchini Co., Ltd. 2% coated product) (comparison f12) were also measured in the same manner, and are also shown in Table 1.

No. 1 Omotegawa Real Estate Examples 4 to S and Comparative Example 5 Methylated methylolmethine (Sumitomo Chemical Co., Ltd. Suil M50W) 25 parts to 48 parts of a 60.9% aqueous solution of glucose
1 part was added and stirred for 20 minutes to obtain a binder solution. 11141111 Machine K for castings preheated in the same manner as Example 1
Add 5 parts of the above viscous 1111M water solution and boil for 8 minutes.
I got it coated with sand. While continuing to knead, add 1ml of iI.
Add 0.1 to 0.1 parts of O, S to 5 to 10 parts of toluene [
The dissolved solution was added and stirred for 2 minutes, and then added to 0.1 part 1 of calcium stearate and further stirred for 50 seconds to create a double wave IN-.

The heat-resistant resins used were styrene anhydride maleic fiber copolymer (Daitsuk 252 manufactured by Amao) and styrene-acrylonitrile copolymer #! The obtained coating, which is a resin (Sevian 105G manufactured by Daicel Chemical Industries), was treated in the same manner as in Example 1 to obtain a constant value of transverse rupture strength, %AM tensile strength, and locking property. Thermal decomposition properties at an ascending speed of 20'C/min were measured using a differential thermal scale made by Ichiu Electric Co., Ltd., and temperatures corresponding to 10%, 50%, and SO% weight were determined. The results are shown in Table 2.

Examples 10 to 15 Examples 4 to 9 were repeated, except that 0.1 to 2 weight of a composition (II type) consisting of a monomer and a polymerization initiator was used in place of the thermoplastic resin solution of Examples 4 to 9. Two-point coated sand was prepared in the same manner and its physical properties were measured. The results are shown in Table 5.

The composition consisting of 7mer and a polymerization initiator was as follows.

■ Strene / maleic anhydride / azobisisobuty-nitrile = 50150/1 ■ I / / = 7015015 ■ # / 'I' / = 76.6 / 25.415 Comparisons 114-5 Thermoplastic resins of real examples 4-9 In place of the solution, a thermoplastic resin solution having the following composition was used to prepare a double value 6N# and its physical properties were measured. The results are shown in the 4th @.

The following thermoplastic resin III liquid was used.

■ Ternary copolymerized nylon (4-4, 10-12, Diamid 11874 manufactured by Daicel Huels) 10% by weight methanol solution for 1i11 ■ Ketone resin (manufactured by Honshu Katei,
- Table 4 shows the results of measuring the physical properties of the SIP using a 20% by weight A7Tone solution for 5 seconds.

Practical Examples 15 to 16 and Comparative Example 6 Cellulose acetate Cgillization degree 28.8%, 2! l'c
10% of the water fII liquid Ii @ viscosity 0.25)
Water-soluble [80 parts of methylated methylolmelamine in 100 parts]
% water solution (15.5 parts per 4 m of Sumitomo Chemical Co., Ltd.) was added and mixed with stirring for 10 minutes to obtain an aqueous binder solution.

The above binder water 1111% 115.554 (sulfur 44100
Double coated sand was prepared in the same manner as in solid line cases 1 and 2 except that it was used for 511. The results of measuring the physical properties of these double-coated sands and of the sand coated only with the binder as a comparative example are shown in Section 5iR.

tst Solid line example 14 Substituting the polystyrene m solution of solid line feed 1, phenol resin (Asahi Zaiko Co., Ltd. Chomu V Light Mp810) 17
% methanol (1 Ill) was added to the soap for 50 seconds with the addition of the viscosity and binder aqueous solution in exactly the same manner as in solid line example 1.

The mixture was stirred for 2 minutes and 50 seconds. After that, 0.1 part of calcium stearate was added and stirred and kneaded for 50 seconds.
Shita. The physical properties of the obtained dual value 6Itlp are shown in Table 6.

Solid line examples 17-18 Same phenolic resin as solid line 1'l14 (M P 810
) k solid line Confucian-1 and exactly the same 4m! 0.59 per 100 parts of 111Ktiil' for 50 trials of adding binder water S
tL I,' Ll, 0 g was added and stirred for 10 seconds.

Thereafter, 1 part % of hequinamethylenetetone was added to the phenol resin as a curing agent, and the mixture was mixed and stirred for 2 minutes.

Addition of 0.1% lucium to stearin was used in a 15% aqueous solution.
Sand was removed from the lagoon for 20 seconds. The excellent physical properties of double-coated sand are
It is shown in Table I6.

Example 19 Instead of the polystyrene layer solution indicated by the solid line fil, an unsaturated polyester resin (isophthalic acid-terephthalic acid system, PXV-5 manufactured by Sumitomo Chemical) was added to acetone to make a 50% solution.
It was dissolved and added so that the solid content was 1% based on 100 parts by weight of #1 silicon.

The physical properties of the double coated sand obtained are shown in Table 6.

Example 20 100 parts % of unsaturated polyester resin used in Example 19
Diallyl phthalate mono-V-555 as a crosslinking agent and 2 parts of benzoyl peroxide as a polymerization initiator were dissolved in 77 tons to make a 5% solution, and in place of the polystyrene M solution in Example 1. , sulfur hardness toog<and the solid content is 0. It was added and mixed so that it became 5%. Table 6 shows the physical properties of the double wave II sand obtained.

Claims (1)

[Claims] ti! ! ? To 100 parts by weight, 1 to 10 parts by weight of methylolmelamine or methylolmefin in alcohol and a water-soluble organic compound having a hydroxyl group are added to cover the surface steel, and then a thermosetting resin or sI# for castings which is mold-free and is made by adding 0.1 to 10 parts by weight of a thermosetting resin to coat the outer S threshold. 1. Patent II JN II No. 1, in which the thermosetting resin covering the outer surface is polystyrene or a copolymer in which 50 moles or more of the polymer composition is sterene.
5. The thermosetting resin coating the outer surface is phenol.