JPH066217B2 - Binder composition for castings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a binder composition in a self-hardening mold and an acid-hardening cold box mold. More specifically, it relates to an improved binder composition for castings, which is mainly composed of a phenol resin or a phenol furan resin, and more particularly to a binder composition suitable for an acid-curable cold box mold. .

[Conventional technology]

As a molding method for producing a mold such as a main mold or a core using an organic binder, a self-hardening mold method, a cold box mold method, and a cloning method (shell method) are known. In particular, organic self-hardening molds have already become a general-purpose molding method in place of the inorganic type from the viewpoints of productivity, casting quality, safety and hygiene mainly in the field of mechanical casting.

On the other hand, conventionally, in order to manufacture a mold at medium to high speed, a cloning method in which a so-called coated sand obtained by coating a granular refractory with a phenol resin is heat-cured to manufacture a mold is widely used.

However, in order to save energy during mold manufacturing, mold production speed, and further improve the quality of the mold and casting, the cold box mold manufacturing method in which it is cured at room temperature with a gaseous or aerosol substance is a mold manufacturing method that replaces the cloning method. It has been tried seriously in the foundry industry.

In the cold box method, an acid-curing cold box in which an acid-curing resin typified by a furan resin is cured with sulfur dioxide using a peroxide as an oxidizing agent, and a polyol and polyisocyanate are catalyzed by an aerosol-like tertiary amine. There is a urethane cold box that cures as.

Among them, the mold using urethane cold box is
There are drawbacks such as poor disintegration property of the casting sand during the production of castings, and sand casting, scooping, pinholes, soot defects and other casting defects.

On the other hand, the acid-curing cold box has been rapidly attracting attention in recent years as a method for solving the above-mentioned problems.

[Problems to be solved by the invention]

BACKGROUND ART Phenolic resins, furan resins, urea resins, melamine resins or modified products thereof have been conventionally used as a binder used in a self-hardening mold method in the field of castings mainly for small quantities of many kinds. However, for the reason of mold characteristics and casting quality, recently, a binder mainly containing a furan resin is widely used. In particular, a phenolic resin is less expensive than a furan resin, but has problems in storage stability, initial strength, and the like, and thus has not been put to practical use sufficiently, and further improvement is desired.

Further, even in the acid-curable cold box for producing a large number of molds of a small number of kinds at a high speed, as the acid-curable resin, furan resin, phenol resin, urea resin and modified resins thereof can be mentioned. At present, in particular, only furan resins are being put to practical use. That is, by the cold box method, an automatic molding machine is used to manufacture a large amount of medium-sized molds, and an acid-curable resin and a peroxide are added and kneaded to the refractory granular material to form a refractory granular material surface. Coating, automatic filling and molding by air pressure, curing, and removal are continuously performed in a cycle of less than 1 minute.
In particular, the phenolic resin is cheaper than the furan resin, but various problems, especially the initial strength is significantly reduced,
Phenolic resins have not yet been put to practical use in the acid-curable cold box method, which requires such high-speed mold production.

The present invention particularly relates to a binder resin composition for castings, which is mainly composed of a phenolic resin or a phenol furan resin having improved initial strength and storage stability of a mold,
In particular, it can be put to practical use in acid-curable cold boxes, which require high-speed mold production, and has a greatly improved initial strength and storage stability of the mold. It is mainly made of phenolic resin or phenolfuran resin, and is a binder for castings. It is an object of the present invention to provide an agent resin composition.

[Means for solving problems]

As a result of earnest research, the inventors of the present invention mainly selected a resin component A mainly composed of a phenol resin or a phenol furan resin having a weight average molecular weight in an appropriate range, and particularly selected a phenol compound or a phenol resin. It was found that the binder composition composed of the two liquids of the resin component B to be used significantly improves the initial strength of the mold without deteriorating the storage stability.

That is, the weight average molecular weight of the acid-curable resin mainly composed of a phenol resin or a phenol furan resin is 300 to 5
It has been found that the initial strength of the mold is improved by the addition of 000, preferably 400 to 3000, and the effect is remarkable especially in the acid-curable cold box method. However, in terms of mold productivity, it is necessary to further improve the initial strength of the mold. Especially in the acid-curable cold box method, the necessity is great. As one of the methods for improving the initial strength of the template, a phenol compound having a substituent such as resorcinol and catechol that enhances the electrification density at the ortho position or the para position with respect to the hydroxyl group in advance, particularly the acid curing property in the self-hardening template method. It is known to add and mix with a resin or a curing agent. On the other hand, the present inventors not only a phenol compound having a substituent that enhances the electrification density at the ortho position or the para position with respect to the hydroxyl group in advance, but also to a phenol resin or a phenol furan resin having a molecular weight in an appropriate range, It was also found that the initial strength of the template is improved by combining at least one of the following (a), (b) and (c).

(a) a resole obtained by subjecting a phenol compound of (a) an unsubstituted or substituted monohydric or dihydric phenol compound or a mixture of two or more compounds to an azodehyde having a molar ratio to the phenol compound of 1.0 or less Type phenolic resin (c) Novolak type phenolic resin However, when these phenolic compounds and phenolic resins are simply mixed with the resin, thickening over time during storage of the resin composition is remarkable, which causes wettability. The effect is significantly reduced due to deterioration. This tendency is particularly remarkable in the acid-curable cold box method. On the other hand, when these phenol compounds are added to the curing agent, depending on the compound, it may be extremely difficult to dissolve or crystals may precipitate. In particular,
In the acid-curing cold box method, when these phenol compounds are added to peroxide as an oxidant and stored, the stability of the peroxide is extremely lowered.

The present inventors have completed the present invention as a result of various studies based on such findings.

That is, the present invention is a resole type resin alone or a furan-based resin obtained by subjecting an unsubstituted or substituted monohydric or dihydric phenol compound to a condensation reaction of an aldehyde having a molar ratio of 1.3 or more to a phenol compound alone or a mixture of two or more kinds. A resin component A mainly composed of a mixture or co-condensate with a resin and a resin component B mainly composed of at least one of the following (a), (b) and (c), and further in the resin component A: The present invention relates to a binder composition for castings, which has a weight average molecular weight of 300 to 5000, preferably 400 to 3000.

(a) a resole obtained by subjecting a phenol compound of (a) an unsubstituted or substituted monohydric or dihydric phenol compound or a mixture of two or more compounds to an azodehyde having a molar ratio to the phenol compound of 1.0 or less Type phenolic resin (c) novolac type phenolic resin The binder composition of the present invention significantly improves the initial strength of the mold without significantly impairing other performances such as storage stability, and significantly improves the mold productivity. Can be improved. The effect is particularly remarkable in the acid-curable cold box method.

The weight average molecular weight of the binder composition with respect to the initial strength of the mold, curing rate, wettability, filling properties, dispersibility of the curing agent, etc.
It seems to be closely related to the balance of complex factors including their interaction. Especially in the cold box method, since the molding sand kneaded with the binder is blown into the mold having a complicated shape with pressurized air, the above relationship is particularly close. Therefore, it is extremely important to adjust the weight average molecular weight of the resin component A within an appropriate range. That is, by setting the weight average molecular weight of the resin component A in the present invention to 300 to 5000, preferably 400 to 3000, the initial strength of the mold is greatly improved. When the molecular weight is out of this range, the initial strength is significantly reduced.

The weight average molecular weight of the composition is determined by GPC (gel permeation chromatography). However, since the average molecular weight may show different numerical values depending on the difference in the column conditions and the measurement conditions such as the standard substance, it is important to define the conditions. The measurement conditions in the present invention are shown in the following examples.

Further, by making the mixing ratio of the resin component A and the resin component B proper, the effect can be further improved. The mixing ratio of the resin component A and the resin component B is 10 by weight.
0: 1 to 100: 200 is preferable, and 100: 3 to 10 is more preferable.
It is 0: 100. If it is less than this mixing ratio, the effect of improving the initial curing strength of the mold is small, and if it exceeds the above mixing ratio, the effect corresponding to the added amount cannot be recognized.

Specific examples of the unsubstituted or substituted monohydric or dihydric phenol compound used in the resin component A of the present invention include phenol, cresol, xylenol, resorcin, methylenebisphenol, and catechol, and preferably phenol, cresol, At least one selected from xylenol.

Further, when the unsubstituted or substituted monohydric or dihydric phenol compound used in the resin component B of the present invention is specifically exemplified,
Phenol, cresol, xylenol, resorcin,
Methylenebisphenol, catechol, alkylresorcin, etc., preferably at least one of phenol compounds having a substituent that enhances the charge density at the ortho or para position with respect to the hydroxyl group, such as xylenol, resorcin, catechol, alkylresorcin, etc. .

As the aldehyde to be condensed with the phenol compound in the resin component A and the resin component B of the present invention, an aromatic aldehyde, an aliphatic aldehyde or the like is used, but an aliphatic aldehyde is preferable. Preferred aliphatic aldehydes are at least one of formaldehyde, paraformaldehyde, glyoxal, acetaldehyde, and more preferred are at least one of paraformaldehyde, formaldehyde or part of them with other aldehydes such as glyoxal and acetaldehyde. It is a modified aldehyde.

The furan-based resin in the present invention means furfuryl alcohol, furfuryl alcohol / aldehyde condensate, furfuryl alcohol condensate, furfuryl alcohol / urea /
Aldehyde condensate, furfuryl alcohol / melamine /
An acid-curable resin mainly composed of aldehyde condensate,
It is not particularly limited.

The resin component A of the present invention is mainly a phenolic resin obtained by mixing or cocondensing a phenolic resin or a furanic resin, but may be mixed or cocondensed with, for example, urea or a urea / aldehyde condensate as a modifier. It is also possible to mix or co-condense at least one of the conventionally known modifiers. Specific examples of conventionally known modifiers include coumarone / indene resin, petroleum resin, polyester, alkyd resin, polyvinyl alcohol, epoxy resin, ethylene / vinyl acetate, polyvinyl acetate, polybutadiene, polyether,
Polymers and oligomers such as polyethyleneimine, polyvinyl chloride, polyacrylic acid ester, polyvinyl butyral, phenoxy resin, cellulose acetate, xylene resin, toluene resin, polyamide, styrene resin, polyvinyl formal, acrylic resin, urethane resin, nylon, and lignin. , Natural products such as ligninsulfonic acid, rosin, ester gum, vegetable oil, bitumen, heavy oil, cashew nut shell liquid, vanillin, tannins, and sugars such as starch, corn starch, glucose, dextrin and derivatives thereof, resorcin residue, Cresol residue, 2,2,
Reaction residues and by-products such as reaction by-products of 4-trimethyl-4- (hydroxyphenyl) chroman and isopropenylphenol, reaction by-products of terephthalic acid and ethylene glycol, polyhydric alcohols such as polyethylene glycol,
Condensates with ketones and aldehydes such as acetone, cyclohexanone, acetophenone, dicyandiamide,
Amino or imino compounds such as acrylamide and thiourea and their aldehyde condensates, furfural,
Examples thereof include aldehyde compounds such as glyoxal and ester compounds such as isocyanuric acid esters and unsaturated fatty acid esters. The modification rate of these modifiers is preferably 20% or less.

Further, the viscosities of the resin component A and the resin component B in the present invention can be adjusted to 1 to 10 at 25 ° C. by controlling the reaction conditions and the diluent.
By setting it to 00 cps, the initial strength of the mold can be further improved. If the viscosity is too low, the resin is effectively adsorbed into the micropores on the surface of the sand grains, and the coating of the resin on the surface of the sand grains is effectively hindered. If the viscosity is too high, the wettability to the foundry sand and the uniform dispersibility of the resin component B in the resin component A are deteriorated.

Specific examples of the diluent that can be used for the above purpose include benzene, aromatic hydrocarbons such as xylene, methanol, ethanol, alcohols such as furfuryl alcohol, diethyl ether, anisole, ethers such as acetal, acetone, Ketones such as methyl ethyl ketone, heterocyclic hydrocarbons such as tetrahydrofuran and dioxane, esters such as methyl acetate and ethyl acetate, polyhydric alcohols such as ethylene glycol and glycerin, and cellosolves such as 2-methoxyethanol and 2-ethoxyethanol. ,
At least one of cellosolve acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate and 2-phenoxyethyl acetate, and carbitol acetates such as diethylene glycol monoethyl ether acetate can be mentioned.
Incidentally, the diluent was previously added to the resin component A or / and the resin component B,
Alternatively, it may be mixed with the resin component A and / or the resin component B, or the mixture of the resin component A and the resin component B immediately before the kneading of the foundry sand. The blending amount thereof is preferably 20% or less with respect to the composition.

The amount of water contained in the composition of the present invention is 10%.
The following is preferable. If it contains more water, the effect of the present invention is significantly reduced. Further, it is preferable that the amount of the monomeric phenol compound contained as an unreacted product is 10% or less. When it contains more monomeric phenol compounds, the initial strength is remarkably reduced or the storage stability is deteriorated. Further, the amount of monomeric aldehyde contained as an unreacted product is preferably 10% or less. When it contains more monomer aldehydes, the workability is significantly deteriorated due to the odor caused by the monomer aldehydes.

Further, a silane coupling agent may be added for the purpose of further improving the strength of the mold. As the silane coupling agent, for example, γ- (2-amino) aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycid Examples include xypropyltrimethoxysilane and the like.

In the present invention, as the curing agent for the self-hardening template method, organic sulfonic acids such as paratoluenesulfonic acid and xylenesulfonic acid, inorganic acids such as phosphoric acid and sulfuric acid, and mixtures thereof are used, but are not particularly limited. Not a thing. Further, as the peroxide of the acid-curable cold box method, ketone-based or aromatic-based organic peroxides and inorganic peroxides such as hydrogen peroxide are used, but are not particularly limited. .

To produce a mold, together with the binder according to the present invention, as the refractory granular material, in addition to silica sand containing quartz as the main component, zircon sand, chromite sand, olivine sand, etc. are used, but are not particularly limited. It is not something that will be done.

The kneading order of the resin component A and the resin component B with respect to the foundry sand may be either the resin component A or the resin component B first, or the resin component A and the resin component B may be mixed in advance just before the kneading into the foundry sand. It may be added to sand. The resin component A and the resin component B may be added and kneaded before or after kneading the curing agent or the peroxide with the molding sand, but since the kneading sand has a longer pot life, in the case of self-hardening, After adding the curing agent,
Further, in the case of the acid-curable cold box method, it is preferable to perform the kneading before adding the peroxide.

〔Example〕

Hereinafter, details of the present invention will be described with reference to examples, but the present invention is not limited to the examples.

The weight average molecular weight in the present invention is a weight average molecular weight in a region on the polymer side from a negative peak caused by water, measured by GPC under the following conditions.

(a) Sample preparation: The composition is dissolved in THF solvent without any special treatment. Concentration; 1%. Insoluble matter: A 0.5 μm membrane filter (made of Teflon) is attached to the syringe and filtered. Injection volume;
20 μl.

(b) Column: Guard column TSK (manufactured by Toyo Soda Kogyo Co., Ltd.) HXL (6.5 mmφ ×
4cm) 1 and TSK3000HXL (7.8mmφ × 30cm) 1 and TSK2500H
One XL (7.8 mmφ x 30 cm).

Guard column → 3000HXL → 2500HXL connection from the inlet side.

(c) Standard substance: polystyrene ((manufactured by Toyo Soda Kogyo Co., Ltd.) (d) Eluent: THF. Flow rate: 1 ml / min (pressure 40 to 70 kg / cm ² ).

(e) Column temperature: room temperature (20-25 ° C) (f) Detector: RI (differential refractometer) (g) Resolution method for molecular weight calculation: time division (2 seconds) However, in the case of RI detector, As shown in FIG. 1, a negative peak due to water appears, and a peak of a low molecular weight compound such as formaldehyde is included in this negative peak. The weight average molecular weight of the resin component A in the present invention means the positive peak (A) on the polymer side excluding the negative peak (B region) shown in FIG.
Area).

The measuring equipment and connection method used in the GPC measurement are as shown in FIG. In the figure, 1 is solvent, 2 is pump, 3 is sample injection valve, 4 is pulsation / pressure / flow rate control circuit, 5 is guard column, 6 is 3000HXL column, 7 is 2500HXL column, 8 is RI detector, 9 is The data processing device, 10 is a waste liquid.

Production Examples 1 to 4 and Comparative Production Examples 1 to 2 Phenol and paraformaldehyde were added to NaOH by an ordinary method.
After reacting for a predetermined time under a basic catalyst, after completion of the reaction, it was neutralized with an aqueous paratoluenesulfonic acid solution and 10% of methanol was added to obtain resin component A having various weight average molecular weights shown in Table 1.

Production Examples 5 to 8 and Comparative Production Examples 3 to 4 Phenol, furfuryl alcohol and paraformaldehyde were reacted under a NaOH basic catalyst for a predetermined time by a conventional method, and after completion of the reaction, neutralized with an aqueous paratoluenesulfonic acid solution and methanol 10 % Was added to obtain resin component A having various weight average molecular weights shown in Table 2.

Production Examples 9 to 14 Various phenol compounds were diluted with the same amount of methanol,
The resin component B shown in the column of the manufacture examples 9-12 of -3 was obtained. or,
The resol type resin reacted by a conventional method with a molar ratio of cresol and formaldehyde of 1: 0.5 was diluted with 40% of tetrahydrofuran to obtain a resin component B shown in the column of Production Example 13 in Table-3. In addition, commercially available novolac type phenolic resin
The mixture was diluted with 10% methanol to obtain a resin component B shown in the column of Production Example 14 in Table-3.

Examples 1 to 13 and Comparative Examples 1 to 5 Various resin components A obtained in the above Production Examples and Comparative Production Examples
Using resin component B and resin component B, the initial strength in the acid-curable cold box method and the initial strength in the self-hardening mold method were measured by the following methods.

The initial strength of the acid-curing cold box method is 100 parts by weight of Australian flattery silica sand, 1.0 parts by weight of resin component A, 0.4 parts by weight of resin component B and 0.5 parts by weight of MEKPO peroxide.
Parts by weight Kneaded mixture is blown into a 25 × 25 × 250 m / m mold with pressurized air to fill it, and then sulfur dioxide gas is blown into the mold to form a mold, after which the sulfur dioxide gas is blown 30 The mold bending strength after 2 seconds was measured.

The initial strength of the self-hardening mold method is 100% by weight of Fremantle silica sand, and 75% of paratoluenesulfonic acid as a curing agent.
Immediately add 0.5 parts by weight of the aqueous solution, 1.0 parts by weight of the resin component A and 0.4 parts by weight of the resin component B, and knead the mixture to obtain 50 m / mφ × 50.
The test piece model of mmh was filled and the compressive strength after 30 minutes was measured.

The results are shown in Table-4.

Examples 14 to 18 and Comparative Example 6 100 parts by weight of Australian flattery silica sand,
Resin obtained in Production Example 2 as resin component A, resin component B
Using the compound obtained in Production Example 11 as the mixing ratio shown in Table 5, the resin component A and the resin component B were added so that the total of the effective components was 1.4 parts by weight. 0.4 parts by weight of oxide was added and kneaded, and the mixture was blown into a 25 × 25 × 250 m / m mold with pressurized air to fill it, and then sulfur dioxide gas was blown into the mold filled with the mixture to form a mold. The mold bending strength was measured 30 seconds after the molding and the blowing of the sulfur dioxide gas.

The results are shown in Table-5.

Examples 19 to 22 and Comparative Example 7 100 parts by weight of Australian flattery silica sand,
1 part by weight of the resin obtained in Production Example 2 as the resin component A,
As resin component B, 0.3 parts by weight of an alkylresorcin / butyl cellosolve acetate solution having a compounding ratio shown in Table 6 and 0.4 parts by weight of a MEKPO-based peroxide were added and kneaded.
Blow and fill with a pressurized air into a mold of × 25 × 250 m / m, then blow the sulfur dioxide gas into the mold filled with the mixture to mold the mold, and 30 seconds after blowing the sulfur dioxide gas The effect of the viscosity of resin component B on the bending strength of the mold was measured.

The results are shown in Table-6.

Example 23 and Comparative Example 8 Resin obtained in Production Example 2 as resin component A, resin component B
Resorcinol / Ethanol (60:40) solution at 50 ℃
After being left for a predetermined number of days, a mold test piece was molded by an acid-curable cold box method by the change in viscosity and the same method as described in Examples 1 to 13, and the bending strength after 30 seconds was observed.

The compound (100/18) of the resin and resorcin obtained in Production Example 2 used as the resin component A as a comparative example was also observed in the same manner.

The results are shown in Table-7.

[Effects of the Invention] As is clear from this example, according to the present invention, a self-hardening mold method and an acid-curable cold box using an acid-curable resin mainly containing a phenolic resin or a phenol-furan resin as a binder. In the method, the initial strength of the mold can be significantly improved without lowering other properties such as decrease in mold strength due to thickening over time. Particularly, the effect is remarkable in the acid-curable cold box method, and the productivity of the mold can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a typical GPC chart of the resin component A obtained by the molecular weight measurement method used in the examples, and FIG. 2 shows the measuring equipment and connection method used in the molecular weight measurement by GPC in the present invention. It is a process drawing. In the figure, 1 is a solvent, 2 is a pump, 3 is a sample injection valve, 4 is a pulsation / pressure / flow rate control circuit, 5 is a guard column, 6 is a 3000HXL column, 7 is a 2500HXL column, 8 is an RI detector, 9 is a data processor, and 10 is a waste liquid.

Claims (7)

[Claims] 1. A resole type resin alone or a furan type resin obtained by subjecting an unsubstituted or substituted monohydric or dihydric phenol compound to a condensation reaction of an aldehyde having a molar ratio of 1.3 or more to a phenol compound alone or a mixture of two or more kinds. Resin component A consisting mainly of a mixture or co-condensate with
And a resin component B containing at least one of the following (a), (b) and (c) as a main component, and a weight average molecular weight of the resin component A is 300 to 5,000. Binder composition for use. (a) a resole obtained by condensation reaction of an unsubstituted or substituted monohydric or dihydric phenol compound or a mixture of two or more phenol compounds of (a) with an aldehyde having a molar ratio to the phenol compound of 1.0 or less Type phenolic resin (c) Novolac type phenolic resin 2. A resin component A having a weight average molecular weight of 400 to 3000.
The composition of claim 1 which is: 3. The weight ratio of resin component A and resin component B is 100: 1.
The composition of claim 1 wherein the composition is -100: 200. 4. The weight ratio of resin component A and resin component B is 100: 3.
The composition of claim 3 wherein the composition is -100: 100. 5. The composition according to claim 1, wherein the phenol compound used for the resin component A is at least one of phenol, cresol and xylenol. 6. The aldehyde used in the resin component A and the resin component B is an aliphatic aldehyde.
The composition according to the item. 7. The composition according to claim 6, wherein the aliphatic aldehyde is at least one of formaldehyde, paraformaldehyde, glyoxal and acetaldehyde.