JPS6228041A - Binder composition for casting - Google Patents

Abstract

PURPOSE:To improve the productivity of a casting mold by constituting a binder of a two-liquid mixture composed of a resin component such as phenolic resin having a specific range of weight average mol.wt. and resin component essentially consisting of an especially selected phenol compd., etc. CONSTITUTION:The phenolic resin or phenol furan resin component having the weight average mol.wt. in a 300-50,000 range is sued as one component. One kind among the mixtures composed of a novolak type phenolic resin, resol type phenolic resin obtd. by condensation reaction with aldehyde having 1.0 molar ratio or monhydric or dihydric phenol compd. is selected and is used as the other resin component. Both resin components are mixed at 100:1-100:200 ratios to constitute the binder. The initial strength of the casting mold is im proved by the above-mentioned method without deteriorating the other per formances of the casting mold. The productivity of the casting mold is conse quently improved.

Description

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

[Conventional technology]

The self-hardening mold method, the cold hosox mold method, and the cloning method (shell method) are known as molding methods for manufacturing 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 are less expensive 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.

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 are cheaper than furan resins, but they have various problems, especially their initial strength, which is significantly reduced.
Phenolic resins have not yet been put to practical use in the acid-curing cold box method, which requires high-speed mold production.

The present invention particularly relates to a binder resin composition for castings 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 greatly 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 have found that resin component A is mainly composed of a phenolic resin or phenolic furan resin having a weight average molecular weight within an appropriate range, and a resin component A mainly composed of a particularly selected phenol compound or phenolic resin. It has been found that a binder composition consisting of two components of resin component B can significantly improve the initial strength of a mold without deteriorating storage stability.

That is, the weight average molecular weight of the acid-curing resin mainly composed of phenol resin or phenol furan resin is 300.
-5000, preferably 400-3000, it has been found that the initial strength of the mold is improved, and this effect is particularly remarkable in the acid-curing cold box method.

However, from the viewpoint of mold productivity, it is necessary to further improve the initial strength of the mold. This is especially necessary in the acid-curing cold box method.

One way to improve the initial strength of a mold is to use a phenolic compound, such as resorcinol or catechol, which has a substituent that increases the charge density at the ortho or para position relative to the hydroxyl group, especially in the self-hardening mold method. It is known to add and mix them into resins or hardeners. 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), (b),
It has been found that the initial strength of the mold can also be improved by combining at least one of (c).

(a) A mixture of one or more unsubstituted or substituted monohydric or dihydric phenol compounds (b) A product obtained by condensing the phenol compound of (a) with an aldehyde having a molar ratio of 1.0 or less to the phenol compound. resol-type phenolic resin (01 novolac-type phenolic resin)However, when these phenolic compounds or phenolic resins are simply mixed with resin, the resin composition significantly increases in viscosity over time during storage, which leads to poor wettability. Its effectiveness is significantly reduced due to deterioration, etc.

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.

As a result of various studies based on this knowledge, the present inventors have completed the present invention.

That is, the present invention is directed to a resol type resin obtained by condensing an unsubstituted or substituted monohydric or dihydric phenol compound alone or a mixture of two or more thereof and an aldehyde having a molar ratio of 1.3 or more to the phenol compound. Consisting of two liquids: a resin component A mainly consisting of a mixture or co-condensate with a furan resin, and a resin component B mainly consisting of at least one of the following (a), ('b), fc), and further a resin component. The present invention relates to a binder composition for foundries characterized in that A has a weight average molecular weight of 300 to 5,000, preferably 400 to 3,000.

(a) A mixture of one or more unsubstituted or substituted monohydric or dihydric phenol compounds (b) A product obtained by condensing the phenol compound of (a) with an aldehyde having a molar ratio of 1.0 or less to the phenol compound. Resol type phenolic resin (c) Novolac type phenolic resin The binder composition of the present invention significantly improves the initial strength of the mold without deteriorating other performances such as storage stability, and improves the productivity of the mold. can be significantly improved. The effect is particularly remarkable in the acid-curing cold box method.

The weight average molecular weight of the binder composition has various effects on the initial strength of the mold, such as curing speed, wettability, filling properties, and dispersibility of the curing agent.
It seems to be closely related to the balance of complex factors including their interactions. In particular, in the cold box method, the above relationship is particularly close because molding sand mixed with a binder is blown into a complex-shaped mold using pressurized air. Therefore, it is extremely important to adjust the weight average molecular weight of resin component A to 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 significantly improved.If the molecular weight is outside this range, the initial strength will be 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 measurement conditions such as column conditions and standard substances, it is important to specify the conditions. The measurement conditions in the present invention are shown in the Examples below.

Further, by adjusting the mixing ratio of resin component A and resin component B, the effect can be further improved. The mixing ratio of resin component A and resin component B is 10 by weight.
The ratio is preferably 0:1 to 100:200, more preferably 100:3 to 100:100. If the mixing ratio is less than this, the effect of improving the initial hardening strength of the mold will be small, and if the mixing ratio exceeds the above, the effect corresponding to the amount added will not 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, resorcinol, methylenebisphenol, catechol, etc., and preferably phenol, cresol, At least one type selected from 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. .

As the aldehyde to be condensed with the phenol compound in resin component A and resin component B of the present invention, aromatic aldehydes, aliphatic aldehydes, etc. are used, but 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.

The furan 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 metal products, etc.
It is not particularly limited.

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 napht, vanillin, tannins, class II and its derivatives such as starch, cornstarch, 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 thiourea; and their aldehyde condensates; aldehyde compounds such as furfural and glyoxal; isocyanurate esters; unsaturated These include ester compounds such as 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 into 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 acetate such as diethylene glycol monoethyl acetate. Note that the diluent may be mixed in advance with resin component A and/or resin component B, or with resin component and/or resin component B, or with 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. Furthermore, it is preferable that the amount of 7mer aldehyde contained as an unreacted product is also 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 coupling agent may be added for the purpose of further improving the strength of the mold. Examples of the silane coupling agent include γ-(2-amino)aminopropylmethyldimethoxysilane, T-aminopropyltrimethoxysilane, T-aminopropyltriethoxysilane,
Examples include T-mercaptopropyltrimethoxysilane 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. May be added to sand. Additionally, resin component A and resin component B may be added and kneaded before or after kneading the curing agent or peroxide into the foundry sand, but in the case of self-hardening sand, since the pot life of the kneaded sand is longer. It is preferable to add the curing agent or, in the case of the acid-curing cold box method, before adding the peroxide and 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.

The weight average molecular weight in the present invention is measured by GPC under the following conditions, and is the weight average molecular weight in a region closer to the polymer than negative peeling due to water.

(a) Sunfill preparation: The composition is dissolved in THF solvent without any special treatment. Concentration: 1%. Insoluble matter: Attach a 0.5-mm membrane filter (made of Teflon) to the syringe and filter.

Injection amount: 2k.

fbl column: Guard column TSK (manufactured by Toyo Soda Kogyo) HXL (6
, 5mowφx4cmH book and TSK300011XL (
7,8mmφX30cm) 1 piece and TSK2500HX
L (7,8vwφX 30cm) 1 piece.

Guard column from the injection port side → 3000) IXL → 250
0) IXL connection.

(c) Standard substance: Polystyrene (manufactured by Toyo Soda Kogyo ■) +dl eluent: TIP, flow rate: 1ml/lll1n (pressure 40-7
0 kg/ci).

(8) Column temperature: Room temperature (20-25°C) (f) Detector: RI (differential refractometer) (Division method for calculating In molecular weight: Time division (2 seconds) However, in the case of R1 detector, As shown in Figure 1, a negative peak due to water appears, and the peak of low molecular weight compounds such as formaldehyde is also included in this negative peak.The weight average molecular weight of resin component A in the present invention is as shown in Figure 1. This is the weight average molecular weight of the positive peak (ApJ area) on the polymer side, excluding the negative peak (BTJ area) shown in FIG.

The measurement equipment and connection method used in the CPC measurement are shown in FIG. In the figure, 1 is the solvent, 2 is the pump, and 3
is the sample injection pulp, 4 is the pulsation/pressure/flow rate control circuit, and 5 is the sample injection pulp.
is a guard column, 6 is a 3000 HX L column, 7 is a 2500) IXL column, 8 is an R1 detector, 9 is a data processing device, and 10 is a waste liquid.

Production Examples 1 to 4 and Comparative Production Examples 1 to 2 Phenol and paraformaldehyde were converted to Na by a conventional method.
React for a predetermined time under an OH basic catalyst, and after the reaction is complete, neutralize with an aqueous solution of para-toluenesulfonic acid and add 10% methanol.
was added to obtain resin component A having various weight average molecular weights shown in Table 1.

Table 1 Production Examples 5 to 8 and Comparative Production Examples 3 to 4 Phenol, furfuryl alcohol, and paraformaldehyde were reacted for a predetermined time under a NaOH basic catalyst using a conventional method, and after the reaction was completed, the reaction was neutralized with an aqueous solution of para-toluenesulfonic acid. , 10% methanol was added to obtain resin component A having various weight average molecular weights shown in Table 2.

Table 2 Production Examples 9 to 14 Various phenolic compounds were diluted with the same amount of methanol to obtain resin component B shown in the columns of Production Examples 9 to 12 in Table 3. Further, a resol type resin prepared by reacting cresol and formaldehyde at a molar ratio of 1:0.5 in a conventional manner was diluted with 40% tetrahydrofuran to obtain resin component B shown in the column of Production Example 13 in Table 3. In addition, a commercially available novolac type phenol resin was diluted with 40% methanol, and production example 1 in Table 3 was prepared.
Resin component B shown in column 4 was obtained.

Table-3 Examples 1 to 13 and Comparative Examples 1 to 5 Resin component A in seeds obtained in the above production examples and comparative production examples
Using and resin component B, the initial strength in the acid-curing cold box method and the initial strength in the self-hardening mold method were measured by the following 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.
A mixture obtained by adding and kneading 0.4 parts by weight of resin component B and 0.5 parts by weight of MEKPO peroxide was mixed with
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 obtained by adding and kneading 0.5 parts by weight of a 5% aqueous solution, 1.0 parts by weight of resin component A, and 0.4 parts by weight of resin component B was immediately filled into a test piece model of 50 m/mφ x 50 mmb, and kneaded for 30 minutes. The subsequent compressive strength was measured.

The results are shown in Table 4.

Table 4 Examples 14 to 18 and Comparative Example 6 Using the resin obtained in Production Example 2 as resin component A and the compound obtained in Production Example 11 as resin component B with respect to 100 parts by weight of Australian flattery silica sand. , at the mixing ratio shown in Table 5 so that the total amount of resin component A added and the effective content of resin component B was 1.4 parts by weight, and MEK
A mixture obtained by adding and kneading 0.4 parts by weight of PO-based peroxide was
5 x 25 x 250 m/m mold by blowing it together with pressurized air, then blowing sulfur dioxide gas into the mold filled with the mixture to form a mold, and after blowing the sulfur dioxide gas, The mold bending strength after seconds was measured.

The results are shown in Table-5.

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 resin component A, and the formulation shown in Table 6 as resin component B. 0.3 parts by weight of alkyl resorcin/butyl cellosolve acetate solution and Mll! A mixture obtained by adding and kneading 0.4 parts by weight of KPO peroxide was blown into a 25 x 25 x 250 m/I11 mold with pressurized air to fill it, and then sulfur dioxide gas was blown into the mold filled with the mixture. A mold was formed, and the influence of the viscosity of resin component B on the mold bending strength 30 seconds after blowing sulfur dioxide gas was measured.

The results are shown in Table-6.

Table 6 Example 23 and Comparative Example 8 Resin obtained in Production Example 2 as resin component A, resin component B
resorcin/ethanol (60:40) solution as
After being left at 0°C for a predetermined number of days, the viscosity change and Examples 1 to 1
A mold test piece was molded using the acid-curing cold box method in the same manner as shown in 3, and the bending strength was observed after 30 seconds.

As a comparative example, a blend of the resin obtained in Production Example 2 and resorcinol (100/18) used for resin component A was similarly observed.

The results are shown in Table-7.

Table 7 [Effects of the Invention] As is clear from this example, the present invention enables self-hardening molding and acid curing using an acid-curing resin mainly composed of phenolic resin or phenol-furan resin as a binder. In the cold box method, the initial strength of the mold can be significantly improved without deteriorating the performance of the mold, such as a decrease in mold strength due to thickening over time. The effect is particularly remarkable in the acid-curing cold box method, and the productivity of molds can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a typical GPC chart of 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 for molecular weight measurement by GPC in the present invention. It is a process diagram. In the figure, 1 is the solvent, 2 is the pump, 3 is the sample injection valve, 4 is the pulsation/pressure/flow control circuit, 5 is the guard column,
6 is a 3000HXL column, 7 is a 2500HXL column, 8 is an R11 dish dispenser, 9 is a data processing device, and 10 is a waste liquid.

Claims (1)

[Claims] 1. A resol type resin obtained by condensing an unsubstituted or substituted monohydric or dihydric phenol compound or a mixture of two or more thereof and an aldehyde having a molar ratio of 1.3 or more to the phenol compound. Consisting of two liquids: resin component A, which is mainly composed of a resin component alone or a mixture or cocondensate with a furan-based resin, and resin component B, which is mainly composed of at least one of the following (a), (b), and (c), and further A binder composition for foundries, wherein the weight average molecular weight of resin component A is 300 to 5,000. (a) A mixture of one or more unsubstituted or substituted monohydric or dihydric phenol compounds (b) A product obtained by condensing the phenol compound of (a) with an aldehyde having a molar ratio of 1.0 or less to the phenol compound. The composition according to claim 1, wherein the weight average molecular weight of the resol type phenolic resin (c) novolac type phenol resin 2 and resin component A is 400 to 3000. 3. The weight ratio of resin component A and resin component B is 100:1 to 1
00:200. 4. The weight ratio of resin component A and resin component B is 100:3 to 1
3. The composition of claim 3, wherein the ratio is 00:100. 5. The composition according to claim 1, wherein the phenol compound used in resin component A is at least one of phenol, cresol, and xylenol. 6. The composition according to claim 1, wherein the aldehyde used in resin component A and resin component B is an aliphatic aldehyde. 7. The composition according to claim 6, wherein the aliphatic aldehyde is at least one of formaldehyde, paraformaldehyde, glyoxal, and acetaldehyde.