JPS6228043A - Binder resin composition for casting - Google Patents

Abstract

PURPOSE:To improve the productivity of a casting mold by constituting a binder of a resin component consisting of a specific resol type resin alone or mixture composed of said resin and furan resin, etc. and a resin component selected from a prescribed phenolic resin, etc. CONSTITUTION:The resol type resin is obtd. by bringing the un-substd. or substd. monovalent or divalnet phenol compd. alone or the mixture composed of >=2 kinds thereof and aldehyde having >=1.3 molar ratio thereto into condensation reaction. Such resol type resin alone or the mixture composed of said resin and furan resin or the co-condensation product thereof is used as one resin component. The other resin component is then selected from resol type, novolak type phenolic resins, etc. Both components are so mixed so as to satisfy formula [I] to constitute the binder in this case. The initial strength of the casting mold is improved and the productivity of the casting mold is improved by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a binder resin composition for self-hardening molds and acid-curing cold box molds. More specifically, the present invention relates to an improved binder resin composition for castings mainly containing a phenolic resin or a phenolic furan resin, and in particular to a binder resin composition suitable for acid-curable cold box molds. It is.

[Conventional technology]

The self-hardening mold method, the cold box mold method, and the cloning method (shell method) are known as molding methods for producing molds such as main molds and cores using organic binders. In particular, organic self-hardening molds are used mainly in the mechanical casting field to improve productivity, casting quality, and
It has already become a general-purpose molding method in place of inorganic molding methods from a safety and health standpoint.

On the other hand, conventionally, in order to manufacture molds at medium to high speeds, a cloning method has been widely used in which molds are manufactured by heating and curing so-called coated sand in which granular refractories are coated with phenolic resin.

However, in order to save energy during mold manufacturing, improve mold production speed, and improve the quality of molds and castings, the cold box mold manufacturing method, which hardens at room temperature using gaseous or aerosol substances, has become an alternative mold manufacturing method to the cloning method. Serious attempts are being made to introduce it in the foundry industry.

The cold box method involves an acid-curing cold box in which acid-curing resins, typically furan-based resins, are cured with sulfur dioxide using peroxide as an oxidizing agent, and polyols and polyisocyanates are cured in an aerosol form of tertiary amine as a catalyst. There is a urethane cold box that hardens as

Among these, molds using urethane cold boxes are
There are disadvantages such as poor disintegration of casting sand during casting production, and the tendency to cause casting defects such as sand trapping, scooping, pinholes, and soot defects.

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

[Problem that the invention seeks to solve]

BACKGROUND ART Phenol resins, furan resins, urea resins, melamine resins, or modified products thereof have conventionally been used as binders for self-hardening molding methods in the field of casting, which focuses on small-lot, high-mix production. However, for reasons of mold properties and quality of castings, binders based on furan resins have recently been widely used. In particular, phenolic resins and phenolic furan resins are cheaper than furan resins, but they have problems with storage stability and initial strength, so they have not been fully put into practical use, and further improvements are desired. It is rare.

In addition, for acid-curing cold boxes that produce molds in small quantities and in large quantities at medium to high speeds, acid-curing resins include furan resins, phenol resins, urea resins, and modified resins of these. In particular, at present, only furan-based resins are being put into practical use. In other words, automatic molding machines are used to manufacture medium to large quantities of molds using the cold box method, in which acid-curing resin and peroxide are added and kneaded to the refractory granular material to coat the surface of the refractory granular material. Covering, filling, molding, curing, and removal are performed continuously in a cycle of less than one minute automatically using air pressure or the like.

In particular, phenolic resins and phenolic furan resins, although less severe than furan resins, have various problems, especially a significant drop in initial strength, so acid-curing cold boxes that require high-speed mold production are According to the method, phenolic resins and phenolfuran resins have not yet been put into practical use.

The present invention particularly relates to a binder resin composition for foundries mainly composed of a phenolic resin or a phenolic furan resin, which has improved initial strength and storage stability of molds.
Caking for castings based on phenolic resin or phenolic furan resin that can be put to practical use in acid-curing cold boxes that require particularly high-speed mold production, and which significantly improves the initial strength and storage stability of molds. The object of the present invention is to provide a synthetic resin composition.

[Means for solving problems]

As a result of intensive research, the present inventors found that the resin component A consists of two liquids: a resin component A mainly composed of a phenolic resin or a phenolic furan resin, and a resin component B mainly composed of a particularly selected phenol compound or phenolic resin. In the binder resin composition, the relationship between the number of moles of aldehyde, the number of furan rings, the number of moles of the phenol compound, and the number of reaction points contained in the composition as a reactant or monomer and the initial strength of the mold. It was found that there is a close relationship between

That is, as one method for improving the initial strength of the mold,
It is known that a phenol compound having a substituent that increases the charge density at the ortho or para position with respect to a hydroxyl group, such as resorcin or catechol, is added to and mixed with an acid-curable resin or curing agent, especially in the self-curing mold method. . On the other hand, the present inventors have developed not only a phenol compound having a substituent that increases the charge density at the ortho or para position relative to the hydroxyl group, but also a phenol resin or a phenol furan resin having a molecular weight within an appropriate range. The following (a), (
It has been found that the initial strength of the mold can also be improved by combining at least one of bl and (c).

(a) A mixture of one or more unsubstituted or substituted monohydric or dihydric phenolic compounds (b) (obtained by condensation reaction of the phenolic compound of al with an aldehyde having a molar ratio to the phenolic compound of 1.0 or less) Resol-type phenolic resin (c1 novolac-type phenolic resin) However, when these phenolic compounds or phenolic resins are simply mixed with resin, the resin composition increases in viscosity over time during storage, which deteriorates wettability. etc., the effect is significantly reduced.

This tendency is particularly noticeable in the acid-curing cold box method.

On the other hand, when these phenolic compounds are added to the curing agent, it may be extremely difficult to dissolve some compounds, or crystals may precipitate. In particular, in the acid-curing cold box method, when these phenolic compounds are added to peroxide as an oxidizing agent and stored, the stability of the peroxide is extremely reduced.

Further, by controlling the mixing ratio of the resin component A and the resin component B within an appropriate range, the initial strength can be further improved. In the process of examining the appropriate range of mixing ratio under various conditions, the present inventors determined the number of moles of aldehyde, the number of furan rings, the number of moles of phenol compound contained in the reactant or monomer state in the composition, and It was discovered that there is a close relationship between the number of reaction points and the initial strength of the mold, and it became possible to further significantly improve the initial strength of the mold. The above relationship is expressed by the following conditional formula (%) [x: Number of moles of aldehyde contained in the form of reactant or monomer in 100 g of composition Y: Composition 10
Number of furan rings contained in 0 g Z,: Number of phenolic hydroxyl groups contained in resin component A in 100 g of composition Z2: Number of phenolic hydroxyl groups contained in resin component B in 100 g of composition kI, kt: The total number of phenolic compounds contained in resin component A and resin component B in one molecule at the ortho and para positions capable of addition reaction with HCHO], and the value is 0.3 to 1. .0, preferably in the range of 0.3 to 0.7, the initial strength is significantly improved.

This effect is particularly remarkable in the acid-curing cold box method. When the value of the conditional expression is outside the range of 0.3 to 1.0, the initial strength is significantly reduced.

The present inventors have completed the present invention based on this knowledge.

That is, the present invention relates to a binder resin composition used in a mold manufacturing method using an acid-curing resin as a binder, which comprises one or more unsubstituted or substituted monohydric or dihydric phenol compounds. The molar ratio of the mixture to the phenolic compound is 1
．． A resin component A mainly consisting of a resol type resin obtained by condensation reaction of three or more aldehydes, or a mixture or co-condensate with a furan resin, and the following (a) and (b).
, 2 of resin component B mainly consisting of at least one of (c)
(a) one or a mixture of two or more unsubstituted or substituted monohydric or dihydric phenol compounds; (b) the phenol compound of (a) condensed with an aldehyde having a molar ratio to the phenol compound of 1.0 or less; The present invention relates to a resol-type phenolic resin (c) obtained by reacting a novolac-type phenolic resin, and a binder resin composition for castings, which is characterized by satisfying the following conditional expression.

(X+Y)/(3xY++xZ++kzxZz)=0
．． 3 to 1.0, preferably 0.3 to 0.7 [x: Number of moles of aldehyde contained in 100 g of the composition in the form of a reactant or monomer Y: Composition 100
Number of furan rings contained in g ZI: Number of phenolic hydroxyl groups contained in resin component A in 100 g of composition Z8: Number of phenolic hydroxyl groups contained in resin component B in 100 g of composition, kl! : The total number of phenolic compounds contained in resin component A and resin component B, respectively, in one molecule at ortho and para positions capable of addition reaction with HCHO] The binder resin composition of the present invention has storage stability. The initial strength of the mold can be significantly improved, and the productivity of the mold can be significantly improved without deteriorating other performances such as properties.

The effect is particularly remarkable in the acid-curing cold box method.

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, butylphenol, nonylphenol, resorcinol, methylenebisphenol, catechol, etc., and preferably General formula (I) (
In the formula, R and R2 are a hydrogen atom or a hydrocarbon group having 1 to 9 carbon atoms), and more preferably at least one phenol compound selected from phenol, cresol, and xylenol.

Further, specific examples of unsubstituted or substituted monohydric or dihydric phenol compounds used in resin component B of the present invention include:
Phenol, cresol, xylenol, resorcinol,
methylene bisphenol, catechol, alkyl resorcin, etc., preferably a phenol compound having a substituent that increases the charge density at the ortho or para position relative to the hydroxyl group, such as at least one of xylenol, resorcin, catechol, alkyl resorcin, etc. .

In addition, the values of , , and in the above conditional formula are the total number of phenol compounds in the molecule at the ortho and rose positions that are capable of addition reaction with formaldehyde, such as phenol,
The kt and kg values of tocresol and 3,5-xylenol are 3. Moreover, a mixture of two or more types of phenol compounds is expressed by an average number depending on the mixing ratio.

The furan-based resin in the present invention refers to furfuryl alcohol, furfuryl alcohol/aldehyde condensate, furfuryl alcohol condensate, furfuryl alcohol/urea/
Aldehyde condensate, furfuryl alcohol/melamine/
It is an acid-curing resin mainly composed of aldehyde condensates, etc.
It is not particularly limited.

The aldehydes in the present invention include aromatic aldehydes,
Although aliphatic aldehydes and the like are used, aliphatic aldehydes are preferred. Preferred aliphatic aldehydes are at least one of formaldehyde, paraformaldehyde, glyoxal, and acetaldehyde, and more preferred are at least one of paraformaldehyde and formaldehyde, or a portion thereof modified with other aldehydes such as glyoxal and acetaldehyde. It is an aldehyde.

Aldehydes are usually contained not only in condensation with phenolic compounds but also in furan resins. Therefore, the aldehyde in the above conditional formula is an aldehyde included in both of them.

The resin component A of the present invention is mainly composed of a phenol resin mixed or co-condensed with a phenol resin or a furan resin, but it may also be mixed or co-condensed with, for example, urea or a urea/aldehyde condensate as a modifier. Alternatively, at least one of conventionally known modifiers can be mixed or co-condensed. Specific examples of conventionally known modifiers include coumaron/indene resin, petroleum resin, polyester, alkyd resin, polyvinyl alcohol, epoxy resin, ethylene/vinyl acetate, polyvinyl acetate, polybutadiene, polyether, polyethyleneimine, and polychloride. Polymers and oligomers such as vinyl, polyacrylic acid ester, polyvinyl butyral, phenoxy resin, cellulose acetate, xylene resin, toluene resin, polyamide, styrene resin, polyvinyl formal, acrylic resin, urethane resin, nylon, lignin, lignin sulfonic acid, Natural products such as rosin, ester gum, vegetable oil, bitumen, heavy oil, crushed cashew nut, vanillin, tannins, W [and its derivatives such as starch, corn starch, glucose, dextrin, resorcin residue, cresol residue, 2. 2.
4-) Reaction residues and by-products such as reaction by-products of limethyl-4-(hydroxyphenyl)coumarone and isopropenylphenol, reaction by-products of terephthalic acid and ethylene glycol, polyhydric alcohols such as polyethylene glycol, acetone, Condensates of ketones and aldehydes such as cyclohexanone and acetophenone; amino or imino compounds such as dicyandiamide, acrylamide, and 1000 urea; and their aldehyde condensates; aldehyde compounds such as furfural and glyoxal; These include ester compounds such as saturated fatty acid esters. The modification rate of these modifiers is preferably 20% or less.

Furthermore, the viscosity of resin component A and resin component B in the present invention can be adjusted to 1 to 1 at 25°C by controlling the reaction conditions and using a diluent.
By setting it to 1000 cps, the initial strength of the mold can be further improved. If the viscosity is too low, the resin will be adsorbed into the microscopic pores on the surface of the sand grains, which will prevent the resin from effectively coating the surface of the sand grains. If the viscosity is too high, the wettability to foundry sand and the uniform dispersibility of resin component B with respect to resin component A will decrease.

Specific examples of diluents that can be used for the above purpose include aromatic hydrocarbons such as benzene and xylene, alcohols such as methanol, ethanol, and furfuryl alcohol, ethers such as diethyl ether, anisole, and 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, cellosolves such as 2-methoxyethanol and 2-ethoxyethanol. ,
Examples include at least one of cellosolve acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, and 2-phenoxyethyl acetate, and carpitol acetates such as diethylene glycol monoethyl ether acetate. In addition, the diluent is resin component A or/and resin component B in advance.
Alternatively, it may be mixed into resin component A and/or resin component B, or a mixture of resin component A and resin component B immediately before kneading the foundry sand. The blending amount thereof is preferably 20% or less based on the composition.

Further, the amount of water contained in the composition of the present invention is 10
% or less. If more water is contained, the effects of the present invention will be significantly reduced. Furthermore, the amount of monomer phenol compounds contained as unreacted substances, etc. is also 10%.
It is preferable that it is below. If more monomer phenol compounds are contained, the initial strength will be significantly lowered or the storage stability will be deteriorated. Further, the amount of monomer aldehyde contained as unreacted substances is also preferably 10% or less. If more monomer aldehyde is contained, workability will be significantly deteriorated due to the odor caused by the monomer aldehyde.

Furthermore, a silane cuffing agent may be added for the purpose of further improving the strength of the mold. Examples of the silane coupling agent include r-(2-amino)aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane,
Examples include γ-mercabutopropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

In the present invention, as the hardening agent for the self-hardening mold method, organic sulfonic acids such as para-toluenesulfonic acid and xylene sulfonic acid, inorganic acids such as phosphoric acid and sulfuric acid, and mixtures thereof are used, but there are no particular limitations. It's not a thing. In addition, organic peroxides such as ketone and aromatic peroxides and inorganic peroxides such as hydrogen peroxide are used as peroxides in the acid-curing cold box method, but are not particularly limited. .

In order to manufacture a mold, silica sand containing quartz as a main component, zircon sand, chromite sand, oripin sand, etc. are used as a refractory granular material together with the binder according to the present invention, but there are no particular limitations. It is not something that will be done.

The order of kneading the resin component A and the resin component B into the foundry sand is that either the resin component A or the resin component B is mixed first. They may be added to the sand, and resin components A and B may be added and kneaded before or after kneading the curing agent or peroxide into the foundry sand, but the pot life of the kneaded sand is longer. From this point of view, in the case of self-hardening, it is preferable to add the curing agent, and in the case of the acid-curing cold box method, it is preferable to add the peroxide before kneading.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 22 and Comparative Examples 1 to 6 A phenol/formaldehyde condensate and a hyphenol/furfuryl alcohol/formaldehyde condensate with known reaction amounts of phenol, furfuryl alcohol, and formaldehyde were synthesized as resin component A by a conventional method, and a resin was prepared. As component B, the phenolic compound or phenolic resin shown in Table 1 or Table 2 is diluted with 40% tetrahydrofuran to form the conditional formula (X+Y)/(3X Y+, X Zl
Various binder resin compositions having values of +2 x zz) shown in Table 1 or Table 2 were obtained. The obtained binder resin composition was used to measure the initial strength in an acid-curing cold box method and a self-hardening mold method.

The initial strength of the acid-curing cold box method was determined by adding 1.0 parts by weight of resin component A to 100 parts by weight of Australian flattery silica sand.
25×
Fill the 25 x 250 m/m mold by blowing it together with pressurized air, then blow sulfur dioxide gas into the mold to form the mold, and measure the bending strength of the mold 30 seconds after blowing the sulfur dioxide gas. did.

The initial strength of the self-hardening mold method is 100% of Freemantle silica sand.
7 parts by weight of para-toluenesulfonic acid as a curing agent
A mixture of 0.5 parts by weight of 5% aqueous solution, 1.0 parts by weight of resin component, and 0.4 parts by weight of resin component B was immediately filled into a test piece model of 50117Ilφ x 5mm, and kneaded for 30 minutes. The subsequent compressive strength was measured.

The results are shown in Table-1 and Table-2.

Example 23 and Comparative Example 7
[Phenol/formalde as a resin component]
After leaving this human shrinkage product and a resorcinol/ethanol solution (60:40) at 50°C for a predetermined number of days, the viscosity change and the value of the above conditional formula should be adjusted to 0.5. Other pieces were molded using the same method as in Examples 1 to 22, such as a mold test, using the acid-curing cold box method, and the bending strength was observed after 30 seconds. As a first comparative example, a formulation in which resorcin was previously cured and blended with resin component A (the amount of resorcin in the composition was the same as in Example 23) was also observed at the same time.

The results are shown in Table 3.

Table 3: Effects of Light] As is clear from the examples, the present invention allows the use of a hard mold method, an acid-curable cold box, and an acid-curable cold box using a caking phenolic resin or an acid-curing resin mainly composed of a phenolic resin. As a result, the mold strength can be significantly improved without reducing the performance of reducing mold strength due to viscosity increase over time. This effect is particularly noticeable in the acidic cold box method, and the productivity of molds can be significantly improved.

Claims (1)

[Scope of Claims] 1. A binder resin composition used in a mold manufacturing method using an acid-curing resin as a binder, comprising one or two unsubstituted or substituted monohydric or dihydric phenol compounds. A resin component A consisting mainly of a resol type resin alone or a mixture or co-condensate with a furan resin obtained by condensing the above mixture and an aldehyde having a molar ratio of 1.3 or more to a phenol compound, and the following (a) ), (b), and (c), (a) a mixture of one or more unsubstituted or substituted monohydric or dihydric phenol compounds; (b) (a) A resol-type phenol resin obtained by condensing the phenol compound with an aldehyde having a molar ratio of 1.0 or less to the phenol compound. (c) A novolak-type phenol resin, further satisfying the following conditional expression. Binder resin composition for foundries. (X+Y)/(3×Y+k_1×Z_1+k_2×Z_
2) = 0.3 to 1.0 [X: Number of moles of aldehyde contained in 100 g of the composition in the form of a reactant or monomer Y: Number of furan rings contained in 100 g of the composition Z_1: In 100 g of the composition Number of phenolic hydroxyl groups contained in resin component A Z_2: Number of phenolic hydroxyl groups contained in resin component B in 100 g of composition k_1, k_2: Number of phenolic compounds contained in resin component A and resin component B, respectively. Total number of ortho and para positions in one molecule capable of addition reaction with HCHO] 2, (X+Y)/(3×Y+k_1×Z_1+k_2×
The composition according to claim 1, wherein the value of Z_2) is from 0.3 to 0.7. 3. The composition according to claim 1, wherein the phenol compound in resin component A and resin component B is a compound represented by general formula (I), and k in the conditional formula is 3. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 and R_2 are hydrogen atoms or carbon atoms from 1 to 9.
4. The composition according to claim 1, wherein the aldehyde is an aliphatic aldehyde. 5. The composition according to claim 3, wherein the phenol compound represented by general formula (I) in resin component A is at least one of phenol, cresol, and xylenol. 6. The composition according to claim 4, wherein the aliphatic aldehyde is at least one of formaldehyde, paraformaldehyde, glyoxal, and acetaldehyde.