JPS6163335A - Phenolic resin binder for shell mold and resin coated sand for shell mold - Google Patents

Abstract

PURPOSE:To prevent the crack of a shell mold without making poor the casting surface of a casting by compounding metallic powder with a phenolic resin as a phenolic resin binder for the shell mold. CONSTITUTION:The phenolic resin binder for the shell mold is prepd. by compounding 1 or >=2 kinds among, for example, Al, Mg, Si, Fe, Ni, Cr, Ti and Nb which have high affinity to oxygen and are easily oxidized as the metallic powder with the novolak type phenolic resin or resol type phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field 1 The present invention relates to phenol I (fatty binder) for shell molds and resin coated sand for shell molds.

Hi? Shell mold is made by cutting sand for molding such as silica sand.
It can be obtained by molding it by interposing it. This shell mold is widely used because it has excellent properties such as a smooth surface and good dimensional accuracy. As a binder for this shell mold, the molar ratio of phenols and heptadhydes is generally 〇.
Novolak type 7 [norm 1 fat] reacted under acidic oil rL at 6 to 0 degrees, or the molar ratio of phenols and alkaline acids was adjusted to 1:1 to 3. Solid resol-type phenol 1δlff1, which has been treated with an alkali to give an anti-Jδ value of 1t, is used, and in the novolak-type phenol 341111, hexamethylenetetrami/ is blended as a curing agent, and resol-type phenol l#IJ is used.
In lt, leave it as it is and heat it to rS5IIF! :Mix it with the sand for i to make a lennon coated sand with a binder coating (i Wr of 1 m), and sprinkle or fill the heated whole stool with this lennon coated sand to make a binder. By melting and hardening the material, it is molded into a shell mold.

However, shell molds using phenolic resin as a binder generally have a problem in that they tend to crack during pouring. This is due to the high heat during pouring.
(This is thought to be caused by the rapid thermal expansion of fat and sand. Therefore, in order to solve this problem, a substance with an effect of 7-el resin and Lennon coated sand was added.) Attempts have been made to make the shell mold flexible and to reduce the coefficient of thermal expansion of the shell mold to prevent the occurrence of cracks. Conventionally, this silane material has been made of up-grade bisphenol A, '6 oil-based...fat, Ronon, etc. are used, but all of these reduce the thermal expansion coefficient of the shell mold and prevent the occurrence of cracks.
Although there is a certain degree of +I-41, there are drawbacks such as thermal decomposition and volatilization at high temperatures, producing a bad odor, and poor disintegration of the 7-el mold after pouring.

In addition, aluminum, tsum and cast iron are sold here at S)J jZ
However, when casting steel with a high degree of 11.ltAr or high manganese steel, cracks may occur due to rapid thermal expansion during pouring. What's more, due to rapid heating, decomposition and volatilization occur rapidly, and the oxidation of phenol (fat itself) causes the formation of sulfur, which can cause the casting to "sashikomi" and In addition, in order to reduce the thermal expansion of the shell mold, it is necessary to reduce the thermal expansion of the shell mold by replacing the fat with bisphenol A or with furkyl phenol. Attempts have been made to modify the water, reduce the 9A bridge density, or add iron oxide, etc., and although some results have been obtained, there are limits and it is not effective for high temperature hot water. If a phenolic resin modified to suppress the crosslinking density is used in this way, the hot strength of the shell mold will decrease and cracks will occur due to insufficient strength, or the resin will carbonize during use. There is also the disadvantage of ν1 when the amount of gas generated is large and the casting surface is deteriorated.

In order to improve this casting surface, conventional coating agents containing graphite, norcon, aluminum oxide powder, etc. have been applied to the surface of the shell mold in order to improve surface precision and strength. Since the agent contains some 411 fat, it increases the coefficient of thermal expansion of the surface that comes into contact with the shell mold, making it more likely that cracks will occur. Since it is used after being diluted with alcohol or diluted with alcohol, it has the disadvantage of requiring a complicated sedentary work of applying the coating and drying it.

As mentioned above, in the past, it has not yet been achieved to prevent cracks in shell molds without damaging the skin of the product. The invention was made in view of the above-mentioned -χ,
The object of the present invention is to provide phenol III fat caking cutting for shell molds and Lennon coach 7 sand for shell molds, which can prevent cracks in shell molds without deteriorating the casting surface of castings. It is.

1 Disclosure of the Invention 1 However, the phenol lubricant caking for shell molds according to the present invention is characterized in that it is composed of phenol (grease) mixed with metal powder C, and the present invention = such a shell mold. Lennon coated sand is characterized by the fact that the surface of the sand is coated with a trap layer formed by caking a 7 liter resin containing metal powder. The present invention will be described in detail below.

Phenol (7-borac type phenol as a 31 fat?
j (1m, resol type 71/-le IJ1 Even if there is a deviation of %l of fat, it will take 1 month, 2 and 2 can be done, this 7 e7-le jl
The metal powders to be mixed with 1F have a high affinity for oxygen and are easily oxidized, such as ⇠bo Δ1, Mg, and Sl.
, Fc, Ni, Cr, Ti% Nb, V, and one or more of these can be used in combination. Metal powders include alloys consisting of two or more of the metals listed above, such as 1-Mg, Al.
-8i etc. can be used. The particle size of the metal powder is preferably 10 μm or less from the viewpoint of uniform mixing and increasing the surface area to facilitate oxidation.

This metal powder is then mixed and dispersed with 7-enol (fat) to prepare a 7-bin resin binder for shell molds, but the mixing is done by blending the metal powder with liquid phenol. Make it.

Specifically, phenols and aldehydes are condensed to form 7-el I [lt to y! During production, metal powders may be blended and mixed, or before this combined reaction product is taken out of the reaction vessel, all Ir powders may be mixed together.
Alternatively, after granulating and cooling the phenol resin, it is heated and melted, and metal powder is added thereto.1. It is possible to mix the phenol resin in a small amount, or even dissolve the phenol resin in a solvent and mix it with the metal powder A in this state. The i1M combined ratio of phenol + 34 fat and metal powder is
Although it varies depending on the performance required of the shell mold, generally 1 to 30 parts of metal powder is added to 100 parts by weight of the resin content of the phenol (preferably about the same amount as a counterfeit part).

As mentioned above, 7 enols (fat caking) for shell molding are prepared, but this phenol ljl fat fli
Coated sand for shell molds can be obtained by meeting and overturning the grain with wJ pear sand.

Coating the sand with 7-enol resin caking can be carried out by a dry hot coating method, a cold foot coating method, a semi-hot coating method, a powder solvent method, or the like. In the dry hot coating method, the above-mentioned solid phenol fat containing metal powder is added to sand heated to 13 to 16 fl °C, mixed, and heated by the sand to form solid phenol. j (melt fat to melt phenol 11111
The surface of the sand is wetted in Step 1 to coat it as a coating layer, and then cooled while maintaining this mixture to obtain granular and smooth Lennon coated sand. The cold coat method uses the metal powder-containing phenol (3(
Lennon coated sand is obtained by dissolving the fat in a solvent such as methanol to form a liquid, adding this to the sand, mixing it, and volatilizing the solvent. In the semi-hot foot method, a liquid phenol resin dissolved in the above-mentioned solvent is added to and mixed with sand heated to 50 to 90°C to obtain Lennon coated sand.

In the powder solvent method, the solid phenolic resin containing metal powder is crushed, the crushed resin is added to sand, a solvent such as methanol is added, and the mixture is mixed to form Lennon Coach 7.
It's something that gets you a lot of attention.

Although granular and smooth Rennon coated sand can be obtained by any of the above methods, the dry hot coating method is preferred from the viewpoint of commercial efficiency. sand and 71
/ - L (The mixing ratio with fat varies depending on the performance required of the shell mold, but in general, the ratio of phenol resin to 100 parts by weight of sand is 1 to 4 in terms of fat solid content)
About parts by weight are preferred, and during this mixing, a curing agent, a silane coupling agent for making the pond sand compatible with the phenol resin binder, etc. can be added as required.

In this way, 1! ), and then sprinkle or fill the heated mold with Lennon coated sand in a conventional manner. Bonding of sand by (1) leaving a shell mold for use.

In these cases, since the metal powder is contained, the low coefficient of thermal expansion of the metal powder suppresses the thermal expansion of the shell mold and prevents the occurrence of cranks in the remold.・3+ Surano, and gold Abe powder is oxidized by reacting with oxygen and b),
Phenol 1 fat f/i during rapid heating during tP audience
The metal powder causes oxygen to be oxidized by the metal powder.
１'

The present invention will be specifically explained using examples for dogs.

', L Ko-v Jijρ11 A 2 liter West So [17 Rasf 7 engineering 7-ru l] 4+1
g, 648 g of 37% formalin, and 5.6 g of sulfuric acid were added and refluxed for about 90 minutes. After the reaction solution was converted to iL, the reaction was continued for another 90 minutes, and then the r? ; After starting pressure dehydration and dehydrating to 150°C, 100 +nrnHg
Further dehydration is carried out at a reduced pressure of
I did this until I got 'C.

Metal aluminum powder with a particle size of approximately 5 μm for dogs! ] 5g was added at will, mixed well for 30 minutes, poured into a vat, cooled, and coarsely crushed to a particle size of 0.5 to 3IIIl. The softening point of the binder was 92°C, and the content of -2 aluminum powder was 10%.

(The pond in which the amount of salmon gen metal aluminum powder added was 9.5 g,
The same procedure as in Example 1 was carried out.

The obtained metallic aluminum-containing novola 7-type phenol +J (the softening point of the fat binder was 88° C. and the content of metallic aluminum powder was 1%).

- to i+a+Example S
．． i, 7.1 at 85°C, 8 in 1 bar 1.5 and 8 in 21 horns for ``7 Lasco''
111. Heat this to melt lγI until the internal temperature is l, 1 +
1 '(:) - Rote - Carefully pour in 165 g of metal aluminum powder in the same way as in Example 1, and ladle 5 (()
I understand that the ring 4'I' city is intervening.

111 Rana'It genus aluminum storage I/borac-type phenol IN (ffrl viscosity 1+'f nQ) softening,','L l:E! At +2.5 °C, the content of metallic aluminum powder was 1()%.

Example! (In a 2 liter four-eye flask, add phenol 47()9,
;(Add 7% formalin 27B and 28% ammonia water 110%, and reduce the internal temperature in about 60 minutes; ()°
C and allowed to react for 4 hours.

The dog was dehydrated under reduced pressure at 70 mmHg, and the indoor bath was heated to 65°.
When the temperature reaches C, 4 pieces of metal silicon powder with a particle size of 6μ...
0g was added, and further pressure concentration was achieved up to 90°C. Immediately, this was poured into a vat, cooled, and then coarsely crushed into pieces with a diameter of 0.5 to 31 mm.

( ) metallic silicon-containing resol type phenol (''I
#The softening point of caking was 83°C, and the content of metal silicon powder was 5%.

Cold 1'' - 7-volac type 7-element resin with a softening point of 90°C 13 Of
1 g in a four-eye flask, and add 70 g of methanol to this.
I added 0g and it was solved (?8).

70. The same metal aluminum powder as in Example 1 was added to the dog.
was added and mixed well to disperse.

The viscosity of the obtained metallic aluminum-containing/borac type phenolic resin binder 7 varnish at 25° C. was 13 poise, and the content of metallic aluminum powder was 5% in terms of solid content tfA.

11: 1300 g of a solid resol type phenolic resin with a softening point of 78°C, which was prepared by reacting in the same manner as in Example 5 except that mfll 1 and metal silicon were not mixed, was placed in a four-eye flask, and 700 g of methanol was added thereto. I melted it well.

Metal aluminum powder for dogs 70. The viscosity at 25°C of the resol type 71/-le antigreasing 7 varnish containing metal aluminum and well-dispersed 7 (1) is +3 poise, and the metal aluminum content is solid part r1. ．． ″
It was C-5%.

Example - AI-M was prepared in the same manner as 'Jc Example 5 except that AI-ME powder was used instead of metal aluminum powder.
A resin caking varnish containing/borac was obtained. The viscosity of this material at 25°C is 13 poise, and Δ
l-M, powder content was 5% in solid calving 1.

Harm - Qiao 1-1 14 fl' C heating L r-7-y Ta IJ - 3t1Kg of silica sand was charged into a whirl mixer, and Example 1 was added to it.
After adding 7511 g of phenol tj (fat binder) and kneading for 3 hours, add 3 tl fl of hexamethylene diamine 110
Dissolve in 1.g of water. Soka [1. IM kneaded until the clumps of sand grains collapsed. Then add 15g of caruntum stearate to it, mix it for 30 seconds, then take it out and aerate it to get Lennon coated sand.

)-ρL822/Borac I! obtained in Example 2! X! 7 x / - The first generation that uses resin caking cutting is an example] -1 and 111
1 person 1 strain Lennon coated sandwich Qr.

A lenone coated sand was obtained in the same manner as in Example 1-1, except that the novolac type phenolic resin obtained in Example 3 (fat binder was used).

``Fire 1 Man'': Resol type 7er obtained in Example 4...Resin futenotosan was prepared in the same manner as in Example 1-1 except that the fat caking yIq was used and hexamethylenetetramine was not used. You can get it.

30 kg of silica sand heated to 80°C was charged into a Whirl mixer, and hexamethylenetetramine 11 (Ig was dispersed in 1150 g of the borac type phenolic resin binder obtained in Example 5). The grains of sand crumble 1
'7J I practiced TIL until it was over. Then, calcium stearate 158 was added and 3() 111 jr4 J
After the center stroke, I pay out 1 here and move 7th lane.
Two Lennon coated sandwiches for 4 hours.

−ni;i! Hyakudo J Yuji 1-- Resol FI'j phenol (
Lennon-coated sand was prepared in the same manner as in Example 5-1 except that varnish was used and hexamethylenetetramine was not used.

Reaction J-7 Two R/borac-type phenols obtained in Example 7! Ike using fat caking varnish obtained Lennon coated sand in the same manner as Ten Jha 1M5-1.

The first generation that does not use the salmon and metal aluminum powder ice is Example]-1
Lennon coated sand was obtained in the same manner as L;1.

lj,! 'i' f1 Lennon coated sand was obtained in the same manner as in Example 4-1 without using the brown metal powder.

Various tests were conducted on the Lennon coated sand obtained in Examples 1-1 to 7-1 and Comparative Example 1.2. The results are shown in the table below.

In the following table, the melting point (°C) is determined by JACT test method 5M
-1, the room temperature bending strength (K g/c+a2-) is JA
Based on CT test method C-1, the rapid thermal expansion coefficient (%
) were tested in accordance with JACT test method 5M-7 at a measurement temperature of 1000° C. in N2. Hot bending strength (Kg/cm”) is J ACT test method 5M
The test piece prepared in -1 was placed in a TL electric furnace set at 1000°C and treated for 1 minute. if&1.
This was done by measuring the bending strength at 1 ml OOOoC. Oxidation resistance is determined by JACT test method SM-7
Test piece (20φ×50INI*
) were placed in an electric furnace set at 1000'C, treated for 5 minutes, taken out, cooled, placed on a vibrating sieve, vibrated for 1 minute, weighed iζ1, and calculated the residue using the following formula. % by weight was extracted to determine the 3'F number.

Weight after treatment/width before treatment x 100 (%)
tg constant of casting surface 1, inner diameter 101) φ, height 21 +1 +1 +*II, wall thickness 2 due to Lennon coated sand
Create an oIIM crucible and add +65 (1'C
This was done by visually inspecting the surface of the cast material that had been cast after pouring hot water into it and then using a cold knife.

(1・1・]mi] Pa1'-11'・ ◎: Very good O: Good
Taniten example c/l et al. 2. It was confirmed that the coefficient of thermal expansion was smaller than that of the comparative example, and that it was effective in preventing cracks from forming in the shell mold.In addition, the oxidation resistance of each example was excellent, and the casting surface was 21 good quality castings
It has been confirmed that 11iL<z can be performed.

Effects of 1-11 Light 1 If the present invention is 1 as described in 1, 7ヱ/-ru 0I fat drying will also be 1. Because the metal powder is included in the cutting material, the low coefficient of thermal expansion of the metal powder makes it difficult to form shell molds.
12 suppresses thermal expansion, and the crank is 11 in the shell mold.
In addition, since gold powder easily reacts with oxygen and is oxidized, γIl
The 7-enol fat caking is oxidized during rapid heating during heating, which is prevented by oxygen being consumed by the 7-enol powder. III
? It is possible to prevent the casting surface of SJJ products from deteriorating due to the generation of sludge that increases the oxidation angle during viscosity cutting.

Claims (4)

[Claims] (1) A phenolic resin binder for shell molds, characterized in that it is made of a phenolic resin mixed with metal powder. (2) Metal powder is Al, Mg, Si, Fe, Ni, Cr
, Ti, Nb, and V. The phenolic resin binder for shell molds according to claim 1, wherein the binder is one or more of Ti, Nb, and V. (3) Metal powder is Al, Mg, Si, Fe, Ni, Cr
The phenolic resin binder for shell molds according to claim 1, which is an alloy of two or more of the following: , Ti, Nb, and V. (4) Resin-coated sand for shell molds, characterized in that the surface of molding sand is coated with a coating layer made of a phenolic resin binder containing metal powder.