JPS59127947A - Resin coated sand composition for shell mold - Google Patents

Abstract

PURPOSE:To improve the quick curability and bending strength of a shell mold formed of molding sand for producing a shell mold by coating the surface of said sand of specific two kinds of novolak type phenolic resins. CONSTITUTION:The resin prepd. by mixing a novolak type phenolic resin having 2.0-7.0 ratio O/P of the methylene group of an ortho bond (O) and para bond (P) indicating the bonding position of the methylene group to the -OH group of a phenol and contg. <=5% lubricant such as ethylene-bis-stearamide and a novolak type phenolic resin having 0.3-1.2 O/P ratio and both having 300-600 number average mol.wt. at a weight ratio of 1:9-9:1 is coated on the surface of molding sand in the stage of manufacturing coated sand which is a raw material for producing a shell mold for casting light alloys, etc. The shell mold using such coated sand cures quickly and has excellent bending strength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin-coated sand composition for shell molds containing a specified) r-lac type phenol (&t), and in particular, has fast curing properties and high bending strength of a piece type. The present invention relates to a resin-coated sand composition V for shell molds having good properties.

Novolak A has been used for a long time in the production of Lennon coated sand for shell molds! ! Phenol resin can be used as a catalyst during reactions such as arsenic acid, hydrochloric acid, sulfuric acid, 'J
acid, = 5 toluenesulfonic acid, benzenesulfonic acid,
Ortho-bond and para-bond (ratio of the number of methylene groups, which indicates the bond of methylene group to 10H group of phenols; hereinafter 0) /P and approximately 1 self) is 0.
3-1.2 Noj? Lac-type phenolic resin (hereinafter referred to as B
0/'P is 2.0 to 7.
．． 0 no? There is a lac type phenolic resin (hereinafter referred to as A resin).

However, each of the 1 Mt lac-type phenols
Renone-coated sand compositions prepared using hexamethylenetetramine as a curing agent for Bm use B-coating (also easy to swallow, slow curing speed, and A-4yi).
When 711# was used for a period of time, it had the drawbacks that it was easy to cause caking and the bending strength of the obtained diseased type was low.

In order to overcome these shortcomings, the present inventors conducted extensive research for five years, and found that by using A resin and B resin together (ml
There is no caking of the fat itself, the hardening speed of the coated sand obtained is fast, and the bending strength of the mold formed is higher than that.
The combination ratio of A resin and B resin is 11 (1° to
The melting ratio is 1:9 to 9:l, but +! FVko7:3~3
Near is preferred.

When the ratio of A resin to B resin exceeds 9:1, the bending of the mold decreases. If the ratio is lower than that, the effect of the above on the hardening speed of the coated sand will decrease. 1. In other words, in any case, the mutual effect of the combined use of A@myo and B resin cannot be achieved.

The number average molecular weight of each of the resin B and the resin B is 300 to 650.
It is desirable that When the ridge average molecular weight is less than 300, the curing speed of the obtained coated sand decreases, and in the case of resin A, the resin itself tends to solidify rapidly. Moreover, when it exceeds 650, resin flow becomes difficult and the bending strength of the mold decreases.

When Resin A and Resin B are added to the refractory granules for molds during the resin-coated sand manufacturing process, each resin may be added in any order. Alternatively, the He resin and the B resin may be pulverized and mixed in solid form in advance, or melt-mixed using a mixer such as an extruder, and then pulverized and added during the manufacturing process of Lennon coated sand.

The phenol salts used in the present invention include phenol,
There are cresol, xylenol, etc., but resorcinol,
Products containing catechol, hydroquinone, aniline, urea, melamine, cashew nut shell oil, etc. can also be used. As the aldehyde, an aldehyde selected from formalin, paraformaldehyde, trioxane, acetaldehyde, etc. is used.

The present invention is preferred by preventing the caking of resin A.For the lubricant to be included in resin A for implementation, ordinary lubricants can be used, but ethylene bisstearamide, methylene bisstearamide, stearinated amide, etc. , methylolstearamide is preferred. There is no problem even if the guide resin contains these lubricants. In addition, this lubricant is used during the production of phenolic resin, before the start of the reaction, during the reaction,
Even if it is added at any time after the completion of the reaction, a phenol (fat) containing a lubricant will be formed.The lubricant formulation I must be 1-.5 weight φ or less per 100 sq. seams of A resin.

5I ((If the amount exceeds the coated sand obtained
This reduces the strength of the mold.

The coated sand manufacturing method employed in the present invention may be any of the dry hot coating method, semi-hot coating method, cold coating method, and powder polishing method, but the present invention is more preferred. A dry hot coat method is recommended for this purpose.

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

In addition, the "part" and "section" that are used in each of the Examples and Comparative Examples all refer to "hi-bu" and "hi-bu".

Production Example 1 A reaction vessel equipped with a cooler and a stirrer was prepared, and 1000 parts of phenol (604 parts of 37% formalin) was added to it, followed by 10 parts of lead capture with #' acid.The temperature was gradually raised until the temperature reached 1. After reaching 96°C, 10 parts of ethylene bisstearamide was added after refluxing for 300 minutes.The mixture was uniformly dispersed.Then, a dehydration reaction was carried out under vacuum.
Unloading and quenching [7] Resin A 960 containing lubricant is solid at room temperature.
6. Production Example 2 Prepare a reaction vessel with a cooler and a stirrer [7. To this, add 1000 parts of phenol, 650 parts of 37-thiformin, and then add
'[10 parts were charged into 6 batches, and the temperature was gradually raised to 96℃.
After reaching 120 minutes, the reflux reaction was carried out for 120 minutes. After that, dehydration reaction was carried out in a vacuum chamber.
985 parts of resin were obtained.

Production Example 3 A reaction vessel equipped with a cooler and a stirrer was prepared, and 1,000 parts of phenol, 604 parts of 1,37% formalin, and then 10 parts of zinc acetate were charged therein. The temperature rises steadily and the temperature is J6℃
After refluxing for 120 minutes, 10 parts of ethylene bisstearamide was added. The mixture was uniformly dispersed. After that, a dehydration reaction was carried out under vacuum, and the
After cooling rapidly, the lubricant contains 850 ml of A-side fat, which is solid at room temperature.

Production 1 line 4 A reaction vessel equipped with a cooler and a stirrer was prepared, and 1000 parts of phenol, 647 parts of #37 polyformalin, and then 10 parts of zinc acetate were charged therein. The temperature was gradually raised, and after the temperature reached 96°C, reflux reaction was carried out for 500 minutes, and then 10 parts of ethylene bisstearamide was added. The mixture was evenly dispersed. Thereafter, a dehydration reaction was carried out under vacuum, and the mixture was cooled down to obtain 1020 parts of lubricant-containing resin A which was solid at room temperature.

Production Example 5 A reaction vessel equipped with a condenser and a stirrer was charged with 1000 parts of phenol, 604 parts of 37% formalin, and then (Iff: 0 parts). ) After W reached 96°C, reflux reaction was carried out for 60 minutes. 10 parts of ethylene bisstearamide was added. The mixture was evenly dispersed. Thereafter, a dehydration reaction was carried out under vacuum to obtain 920 parts of lubricant-containing Resin B which was solid at normal ta and was cooled.

Production Example 6 A reaction pot with a cold 1] container and a stirrer was prepared in a quasi-11 m1 volume, and 1000 parts of phenol, 690 parts of 37% formalin,
Next, 10 parts of oxalic acid was charged. The temperature gradually increases until the temperature reaches 9
After reaching 6°C, reflux reaction was carried out for 240 minutes, and then 10 portions of ethylene bisstearamide were added. 711. After dispersing the compound and performing a dehydration reaction under vacuum, it is cooled and mixed with lubricant Naiku B Resin 108, which is solid at room temperature.
Got 5 copies.

Production Example 7 The 700Ky of lubricant-containing resin A obtained in Production Example 1 and the 300Ky edge of B resin obtained in Production Example 2 were each crushed and uniformly mixed in a machine mixer for 1 hour. This mixture is L/D
: Pour into the conch of an extruder with a No. 8 screw, and extrude at 7 o'clock with an internal temperature of 150°C and a discharge weight of 40 kg.
After that, it was rapidly cooled and crushed to obtain a resin of 875K9.

Example: Miki No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
8 parts of A resin containing lubricant obtained in Production Example 1 and B obtained in Production Example 2.
After applying 42 parts of resin, it was kneaded for 40 seconds.

Next, 21 parts of hexamethylenetetramine dissolved in 105 parts of water was added and kneaded until the coated sand disintegrated. Further, Steering 1 Calcium Ff was added, mixed for 30 seconds, and the sand was removed and aerated to obtain a resin coated sand composition.

Example 2 Miki No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
42 parts of the lubricant Naiku A resin obtained in Production Example 1 and +8 parts of the B resin obtained in Production Example 2 were added to the mixer for 40 seconds.

Next, 21 parts of hexamethylenetetramine was dissolved in 105 parts of water and mixed until the coated sand was completely destroyed.Additionally, 71 parts of calcium stearin was added; Mix for 30 seconds and
After removing the sand and carrying out the process, I found that the composition of the Lennon coated sand was tested.

Example 3 Miki No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 140 parts of the mixed resin obtained in Eija 117, the mixture was kneaded for 710 seconds. Then, 21 parts of hexamethylenetetramine was added to 105 parts of water.
The coated sand was dissolved in a portion and kneaded under excitation L7 until the coated sand disintegrated. Further, 7 parts of calcium stearate was added, mixed for 1.30 seconds, and aeration was performed by removing the sand to obtain a Lennon coated sand composition.

Comparative Example 1 Cubic No. 6 silica sand 700 heated to +1i3o to 140°C
After adding 8 parts of lubricant-containing resin A obtained in Production Example 3 and 42 parts of lubricant-containing resin B obtained in Production Example 5, the mixture was heated for 40 seconds. Kneaded. Next, 21 parts of hexamethylenetetramine was dissolved in 105 parts of water, and the coated sand was prepared by dissolving it in 105 parts of water.
The mixture was kneaded until D4. Furthermore, 7 parts of calcium stearate was cooled and mixed for 1.30 seconds, and the sand was removed and aerated to obtain a resin coated sand composition.

Comparative Example 2 Cubic No. 6 silica sand 700 DO heated to a temperature of 130 to 140°C
0 part was charged in a whirl mixer, 8 parts of lubricant-containing A1 g I fat obtained in Production Example 4, and 42 parts of resin from the lubricant obtained in Production Example 6 were cooled, and 40 Kneaded for seconds. Next, 21 parts of hexamethylenetetramine was added to 1 part of water.
The mixture was dissolved in 0.05 parts and added, and mixed until the coated sand collapsed. Furthermore, 7 parts of calcium stearate was added, mixed for 30 seconds, and sand aeration was performed to obtain a resin coated sand composition 1. Comparative Example 3 Sanei No. 6 silica sand 70 heated to a temperature of 130 to 140°C (1
0 part was placed in a Whirl mixer, and after removing 98 parts of the A4 fat in the lubricant obtained in Production Example 3 V and 42 parts of B resin obtained in Production Example 2, the mixture was kneaded for 40 seconds. .

Next, 21 parts of hexamethylenetetramine was dissolved in 105 parts of water and added, and the mixture was kneaded until the coated sand crumbled. Additionally, 7 parts of calcium stearate are added.
Mix for 30 seconds, remove sand and aerate,
A resin coated sand composition was obtained.

Comparative Example 4 Cubic No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
After adding 7 parts of lubricant-containing resin A obtained in Production Example 1 and 133 parts of B resin obtained in Production Example 2, the mixture was heated for 40 seconds/l! , practiced. Next, 21 parts of hexamethylenetetramine was cooled with water 1-2,
: The mixture was mixed for 30 seconds, the sand was removed, and aeration was performed to obtain a Lennon coated sand composition.

Comparative Example 5 Cubic No. 6 silica sand 7000 heated to a temperature of 130 to 140°C
Example] V (
133 parts of lubricant-containing resin A, and Production Example 2
7 parts of B resin obtained in step 7 was dissolved in 105 parts of water and added thereto, followed by mixing until the coated sand collapsed. Furthermore, 7 parts of calcium stearate was cooled, mixed for a few seconds, the sand was removed, and aeration was performed, and the Lenonko dead sand surface I was completely coated.

The characteristic values of each resin obtained in Production Example 1.2.3.4.5.6 are shown in the first-! Table 2 shows the properties 11M of the resin coated sand obtained in Example 1.2.3 and Comparative Example 1.2.3.4.5.

The method for testing the soap is as follows.

IA insect point: J Engineering E' -K - (07P according to 1064): Based on the constant line of proton number of 2.2' methylene, 2,4' methylene, 4.4' methylene by nuclear magnetic resonance spectrum.

Number average molecule ht: Based on vapor pressure equilibrium method.

Viscosity, point a: According to JAOT test method c-1.

Bending strength: 3 according to JAOT test method 5M-1, hot tensile strength: according to JAOT test method sM-10.

Claims (3)

[Claims] (1) Novolak with a methylene group ratio (0/P) of 2.0 to 7.0 between the ortho bond (0) and the para bond (P), which indicates the bonding position of the methylene group to the 10H group of the phenol. Type phenolic resin (A) O/P is 0.3~
1.20 no? Resin-coated sand composition 3 for shell molds containing easy-type phenolic resin (B)
゜ (2) Novolac! The ratio of the phenolic resin (A) to the novolac type phenolic resin (B) is 1 = 9 to 9
: 1. The Lennon coated sand composition for shell molds according to item 1 of the patent claim. (3) Nogalac-type phenolic tree DW (A) B
Resin coated sand set 11 for shell mold according to claim 1 or claim 2, wherein each of the lac type phenolic resin (B) has a number average molecular weight of 300 to 650. 1, (4) Lac-type phenol 1 () (effect (A) is 5 (J'i@:%) or less of lubricant, ff , the resin-coated sand composition for shell molds according to item 2 or 3.