JP3324718B2 - Binder-curing agent kit for mold production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder-curing agent kit comprising a combination of a binder and a curing agent composition, which is used for producing a mold.

[0002]

2. Description of the Related Art Conventionally, a mold is prepared by filling a mold (model) with kneading sand obtained by kneading a refractory granular material and a binder, and then curing the binder with a predetermined curing agent. It is manufactured by. For example, in the field of cast steel, a water glass / CO ₂ method and a water glass / diecal method using a binder mainly composed of water glass are used. In recent years, various organic curable resins such as a furan resin, a resol-type water-soluble phenol resin, and a urethane resin have been developed and used as binders replacing water glass. Among them, the resol-type water-soluble phenol resin is cured with an organic ester or carbon dioxide gas, so that it is possible to prevent deterioration of the working environment at the time of producing a self-hardening or gas-curable mold, and is suitable as a binder instead of water glass (Japanese Patent Laid-Open No. 50-13062)
7, JP-B-61-43132, JP-B-61-37022).

[0003] However, when the binder made of the resol-type water-soluble phenol resin and the refractory granular material are kneaded to produce a mold, compared with the case where a binder made of a furan-based resin is used, There were the following disadvantages. That is, there was a defect that the strength of the obtained mold was low and the surface stability of the obtained mold was poor. These disadvantages are:
In each case, the cured resol-type water-soluble phenolic resin has a low cohesive strength and is generated.

[0004] In order to improve the cohesive strength of the resol-type water-soluble phenolic resin, a two-component binder comprising a compound having an epoxy group such as a hydrophilic epoxy resin oligomer mixed with the resol-type water-soluble phenolic resin. It has been known that the following method can be used (JP-A-4-298591). However, since the two-component binder has a low curing rate but is room temperature curable, if a two-component binder is prepared in advance, the curing starts with the passage of time. After that time, it could not be used anymore. Therefore, immediately before use, a resol type water-soluble phenol resin and a hydrophilic epoxy resin oligomer are mixed to prepare a two-component binder. However, this two-component binder has a very low curing rate as described above, and cannot be used as a binder for mold production. In other words, it is not possible to quickly remove the manufactured mold (remove the mold from the mold),
There is a drawback that the use efficiency of the mold is reduced and a practical mold cannot be manufactured.

[0005]

Therefore, the present invention does not use the above-mentioned two-component binder, but uses a resole type water-soluble phenol resin as the binder and has an epoxy group. By compounding and using the compound with an organic ester as a curing agent, a mold having high production efficiency, high strength and good surface stability can be produced.

[0006]

That is, the present invention comprises a combination of a binder containing a resol type water-soluble phenolic resin and a curing agent composition containing a compound having an epoxy group and an organic ester. The present invention relates to a binder-curing agent kit for producing a mold.

The binder used in the present invention is generally a resol type water-soluble phenol resin. The resole type water-soluble phenol resin is obtained by condensing a phenol and an aldehyde compound in the presence of an alkaline catalyst such as potassium hydroxide. Phenols include phenol, cresol,
Alkylphenols such as 3,5-xylenol, nonylphenol, p-tert-butylphenol, isopropenylphenol and phenylphenol, polyphenols such as resorcinol, catechol, hydroquinone and phloroglysin, bisphenol A, bisphenol F, bisphenol C and bisphenol E Bisphenols and the like are used. Also, cashew nut shell liquid, lignin,
Those comprising a mixture of phenolic compounds such as tannins can also be used as phenols. One of these various phenols may be used alone, or two or more of them may be mixed and co-condensed with the aldehyde compound.

As the aldehyde compound to be condensed with phenols, formalin, paraformaldehyde, furfural, glyoxal and the like are used. The amount of the aldehyde compound used is 1 to 3 mol, preferably 1.5 to 2 mol, per 1 mol of the phenol. If the amount of the aldehyde compound is less than 1 mol, even if the obtained binder made of the resol-type water-soluble phenol resin is cured, the binding power is not sufficient, and the mold strength tends not to be improved. Conversely, if the amount of the aldehyde compound exceeds 3 mol, the aldehyde odor from the resole-type water-soluble phenol resin is strong, and the working environment tends to deteriorate.

[0009] The condensation of phenols and aldehyde compounds is generally carried out in an aqueous alkaline solution to obtain a resole-type water-soluble phenol resin. At this time, potassium hydroxide (KOH) is preferably used as a reaction catalyst, and condensed in an aqueous potassium hydroxide solution. In addition, since the resol-type water-soluble phenol resin is generally supplied in the form of an aqueous alkali solution, a predetermined amount of potassium hydroxide may be used at the time of condensation, and a minimum amount of hydroxide may be used as a reaction catalyst. After completion of the condensation using potassium, a predetermined amount of potassium hydroxide may be added. After completion of the condensation, amines such as sodium hydroxide (NaOH), lithium hydroxide (LiOH) or hexamethylenetetramine may be used together with potassium hydroxide so as to have a predetermined alkalinity. . In the aqueous alkali solution of the resole type water-soluble phenol resin, the number of moles of the alkali (base) is preferably 0.03 to 1 mole per 1 mole of the phenolic hydroxyl group. Here, the phenolic hydroxyl group is
All O in the resole type water-soluble phenol resin
An H group, that is, an OH group directly bonded to an aromatic ring and an OH group bonded to an aromatic ring via a methylene group are included. 0.03 moles of alkali (base)
If the amount is less than the mole, the caking force of the cured resol-type water-soluble phenol resin tends to decrease. Conversely, when the number of moles of the alkali (base) exceeds 1 mole, the solution becomes a strong alkali aqueous solution, which is dangerous in handling.

The binder in the form of an aqueous solution containing a resol-type water-soluble phenol resin may contain a silane coupling agent in order to improve the strength of the resulting mold. Various conventionally known silane coupling agents can be used. Particularly, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ- (2-aminoethyl) aminopropyltripropylsilane It is preferable to use methoxysilane, N-glycidyl-N, N-bis [3- (trimethoxysilyl) propyl] amine and the like. The viscosity of the aqueous binder solution containing or not containing the silane coupling agent is preferably 800 cps or less at 25 ° C., and particularly preferably 200 cps or less. When this viscosity exceeds 800 cps,
There is a tendency that it becomes difficult to uniformly knead with the refractory granular material. This viscosity was measured by a B-type viscometer. The solid content of the binder aqueous solution, that is, the content excluding water (the content of the resol-type water-soluble phenol resin and the silane coupling agent) is 35 to 75% by weight. preferable. If the solid content is less than 35% by weight, the strength of the resulting mold tends to be insufficiently improved. On the other hand, if the solid content exceeds 75% by weight, the viscosity tends to exceed 800 cps, and it tends to be difficult to uniformly knead with the refractory granular material. The solid content was determined by heating a weighed sample (2.0 ± 0.1 g) in a hot air dryer at 105 ° C. for 3 hours to evaporate water.
(Weight of sample after water evaporation / weight of weighed sample) x 100 =
It is calculated by the formula of solid content.

On the other hand, in the present invention, a curing agent composition for curing a resol-type water-soluble phenol resin at room temperature is composed of a compound having an epoxy group and an organic ester. Examples of the compound having an epoxy group include polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanurate, and glycerol polyglycidyl ether. Epoxy compounds, ethylene-propylene glycol diglycidyl ether, propylene-polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, resorcin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol diepoxy compounds such as S diglycidyl ether, phenol (EO) ₅ glycidyl Ether, p-tert-butylphenyl glycidyl ether, 2
Monoepoxy compounds such as -ethylhexyl glycidyl ether and the like can be used.

As the organic ester in the curing agent composition, methyl formate, triacetin, γ-butyrolactone, ethylene glycol monoacetate, ethylene glycol diacetate and the like can be used. This curing agent composition is generally supplied in the form of a solution. When a curing agent composition containing a compound having an epoxy group and an organic ester is used, the weight ratio between the compound having an epoxy group and the organic ester is preferably as follows. That is, the amount of the organic ester is preferably 0.02 to 99 parts by weight based on 1 part by weight of the compound having an epoxy group. When the amount of the organic ester exceeds 99 parts by weight, the amount of the compound having an epoxy group becomes relatively small, and the strength of the obtained template tends to decrease. Conversely, when the amount of the organic ester is less than 0.02 parts by weight, the curing speed of the binder decreases, and the production efficiency of the mold tends to decrease.

The aqueous solution-type binder containing the resol-type water-soluble phenolic resin prepared as described above, and the solution-type curing agent composition comprising a compound having an epoxy group and an organic ester are: As described below, the refractory granular material is added and kneaded to produce a mold. That is, first, a hardener composition solution is added and kneaded to the refractory granular material to obtain a mixture in which the refractory granular material and the hardener composition solution are uniformly mixed. Thereafter, a binder aqueous solution containing a resol-type water-soluble phenol resin is added to the mixture and kneaded to obtain a sand composition. Needless to say, a binder aqueous solution and a curing agent composition solution are separately prepared and added and kneaded with the refractory granular material as needed (the order and amount of addition and kneading are arbitrarily determined).
Thus, a sand composition can be obtained. The sand composition is filled in a mold (model), and when the binder has hardened to a certain extent, the mold is removed (removed) and left for about 24 hours. It can be cured to obtain a high-strength mold. In the production of such a mold, the amount of the resol-type water-soluble phenol resin in the binder and the amount of the compound having an epoxy group in the curing agent composition solution to the refractory granular material are as follows. preferable. That is, with respect to 100 parts by weight of the refractory granular material,
The resole type water-soluble phenol resin is added so as to be 0.5 to 6 parts by weight, and the compound having an epoxy group is 0.0025 to
It is preferable to add so as to be 3 parts by weight. As the refractory granular material to be used, conventionally known various materials can be used. For example, quartz sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic quartz whose main component is quartz is used. Mullite sand or the like can be used. In addition, as the refractory granular material, those mainly composed of these reclaimed sand and recovered sand can also be used.
Needless to say.

As is clear from the above-described method for producing a mold, the binder and the curing agent used in the present invention are supplied to a mold manufacturer in the form of a kit. That is,
A binder containing a resol-type water-soluble phenolic resin,
A combination of a compound having an epoxy group and a curing agent composition containing an organic ester is supplied as a kit. In particular, it is preferable that the binder is in the form of an aqueous solution, the curing agent composition is in the form of a solution, and the two are combined and supplied in the form of a kit. It is preferable that the weight ratio of the binder and the curing agent composition supplied as a kit is set as follows. That is, the amount of the compound having an epoxy group in the curing agent composition is set to 0.5 to 5 parts by weight with respect to 100 parts by weight of the resol-type water-soluble phenol resin (solid content) in the binder. Is preferred. When the compound having an epoxy group is set in this range, the curing speed of the binder in obtaining the mold is high, the strength of the mold after 4 hours is high, and the SSI% (surface stability of the mold) is also good. Become. When the compound having an epoxy group deviates from this range, at least one of these physical properties is slightly reduced, and in particular, the curing rate of the binder tends to be slow.

[0015] Further, in a binder comprising an aqueous solution of a resol-type water-soluble phenol resin used in the present invention or in a curing agent composition solution, a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant is used. By incorporating various surfactants such as a dispersant, or organic nitrogen compounds such as urea, urea compounds and amide compounds, the fluidity of sand composition kneaded with the refractory granular material and the filling property to the model are improved. Can be done. Furthermore, when reclaimed sand is used as the refractory granular material, the strength of the resulting mold can be improved by incorporating various polyvalent metal salts such as calcium chloride and aluminum oxide.

[0016]

【Example】

Examples 1 to 7, Comparative Examples 1 and 2 In 50% aqueous KOH solution, phenol was added in an equimolar ratio to KOH and stirred and dissolved. While maintaining the aqueous solution at 80 ° C., gradually add a 50% aqueous formalin solution so that formalin becomes 2 mol per 1 mol of phenol,
The condensation reaction between phenol and formalin was allowed to proceed. Then, the reaction was continued at 80 ° C. until the viscosity of the reaction solution reached 120 cps (25 ° C.). When this viscosity is reached, the reaction solution is cooled to room temperature and phenolic hydroxyl groups 1
50 moles so that the number of moles of KOH is 0.70
% KOH aqueous solution was added to obtain a resin aqueous solution. 0.5 part by weight of γ-glycidoxypropyltrimethoxysilane was added to 100 parts by weight of this resin aqueous solution, and the viscosity was 70 cps (25 cps).
C), a binder comprising an aqueous solution of a resole-type water-soluble phenol resin was obtained. The solid content of the resol-type water-soluble phenol resin aqueous solution was 50% by weight.

On the other hand, as shown in Table 1, nine types (Nos. 1 to 9) of a mixture of a compound having an epoxy group and an organic ester at a predetermined ratio were prepared as curing agent composition solutions. Then, 0.3 part by weight of each hardener composition solution was added and kneaded to 100 parts by weight of silica sand (freemantle) as a refractory granular material. Thereafter, 1.5 parts by weight of a binder composed of an aqueous solution of a resol-type water-soluble phenol resin was added and kneaded,
A sand composition was obtained.

[0018]

[Table 1]

Then, the sand composition immediately after kneading is mixed with 50 mmφ × 50
The test piece frame was filled in a mmh test piece frame, and a test mold was obtained by a self-hardening mold manufacturing method. The curing test was performed at an ambient temperature of 25.
C., sand temperature 25.degree. C., humidity 60% RH. Then, the compressive strength of the obtained test mold after 30 minutes has passed [kg /
cm ² ], compressive strength after 1 hour [kg / cm ² ], compressive strength after 2 hours [kg / cm ² ], compressive strength after 24 hours [k
g / cm ² ] were measured and the results are shown in Table 2. Table 2 also shows the surface stability (SSI) of the obtained template.

[0020]

[Table 2]

The SSI (%) in Table 2 indicates the surface stability of the mold, and the test method of the organic mold was used for the test method [mold test method immediately after kneading] Conference report (February 1986)] 104 Test method for surface stability of organic template p7. That is, the test mold is shaken on a sieve for 60 seconds, and the weight after shaking is measured. Then, the weight of the test mold before shaking is changed to W
Assuming that the weight of the test mold after shaking is ₁ (g) and the weight of the test mold after shaking is W ₂ (g), the SSI (%) can be obtained by the following equation. That is,
SSI (%) = (W ₂ / W ₁ ) × 100. Therefore, S
The SI (%) indicates that the larger the value, the better the surface stability of the mold.

As is clear from the results in Table 2, when a curing agent composition comprising a compound having an epoxy group and an organic ester was used, only the organic ester was used without using a compound having an epoxy group. It can be seen that the mold strength (compressive strength) after 24 hours has elapsed after kneading is higher than in the case of using (Comparative Example 1). In addition, as compared with the case where only a compound having an epoxy group was used without using an organic ester as the curing agent composition (Comparative Example 2), the initial curing speed, specifically, 30 minutes to 2 minutes after kneading. It can be seen that the cure speed over time has become very fast.

Examples 8 to 13 As shown in Table 3, six types of curing agent composition solutions were prepared by mixing a compound having an epoxy group and an organic ester at a predetermined ratio. Then, 0.3 part by weight of each hardener composition solution was added and kneaded to 100 parts by weight of silica sand (freemantle) as a refractory granular material. Thereafter, 1.5 parts by weight of the aqueous binder solution used in Example 1 was added and kneaded to obtain a sand composition. Then, a test mold was manufactured in the same manner as in Example 1, and the compressive strength after one hour had passed [kg / cm ² ].
Was measured, and the results are shown in Table 3.

[0024]

[Table 3]

As is apparent from the results, when the amount of the compound having an epoxy group exceeds 5 parts by weight with respect to 100 parts by weight of the resole type water-soluble phenol resin, the compressive strength after one hour has been slightly lowered. I understand. That is, based on 100 parts by weight of the resol type water-soluble phenol resin (solid content),
The smaller the amount of the compound having an epoxy group is less than 5 parts by weight, the faster the curing speed of the binder is. This does not mean that the curing rate increases as the amount of the curing agent composition increases with respect to the resol-type water-soluble phenol resin in the aqueous binder solution. It suggests that it is preferred to use.

[0026]

As described above, in the present invention, as a curing agent composition for curing a binder (mainly a resol type water-soluble phenol resin) used at the time of manufacturing a mold at room temperature, an epoxy resin is used. What consists of a compound having a group and an organic ester is used. The compound having an epoxy group functions to cure the binder and binds (polymerizes) with the binder to form one unit of a three-dimensional network structure. Then, the caulking force of the hardened binder is improved. Further, the organic ester in the curing agent composition can remarkably increase the curing speed of the binder. Therefore, if the sand composition is filled into a mold,
Since the curing starts immediately and a certain level of mold strength can be obtained, the mold can be removed (removed) immediately after filling with the sand composition. Therefore, the viscosity according to the present invention
Using a binder- curing agent kit , if a mold is obtained by a self-hardening mold manufacturing method or the like, the use efficiency of the mold can be significantly improved, and the strength is high and the surface stability is excellent. This produces an effect that a template can be obtained.

In producing the mold, a resol type water-soluble phenol resin as a binder and a compound having an epoxy group in the curing agent composition are mixed at a specific weight ratio, that is, 100 parts by weight of the former. On the other hand, when the latter is used in the range of 0.5 to 5 parts by weight, there is an effect that the curing speed of the mold is particularly improved.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B22C 1/00-3/00

Claims (2)

(57) [Claims] 1. A binder for producing a mold, comprising a combination of a binder containing a resol-type water-soluble phenolic resin and a curing agent composition containing a compound having an epoxy group and an organic ester. Agent-curing agent kit. 2. The binder-curing agent kit for producing a mold according to claim 1 , wherein the compound having an epoxy group is contained in an amount of 0.5 to 100 parts by weight of the resol-type water-soluble phenol resin (solid content). A binder-curing agent kit for producing molds, which is combined so as to be 5 parts by weight.