KR102614246B1 - Hybrid binder composition for casting metal component - Google Patents

Abstract

The present invention relates to a hybrid binder composition for casting metal parts, which comprises: sand; a binder falling under a furan-based organic binder; a catalyst; and a filler falling under an inorganic hybrid compound. The filler is arranged as reactive nano silica having a hydroxy group as a reaction group on a surface by causing a surface modification reaction using a silane coupling agent on a nano silica based on tetraethylorthosilicate (TEOS). Therefore, various properties can be improved.

Description

Hybrid binder composition for casting metal parts {HYBRID BINDER COMPOSITION FOR CASTING METAL COMPONENT}

The present invention relates to a hybrid binder composition for casting metal parts.

In order to overcome the disadvantage of extremely high investment costs in production facilities when producing products with complex shapes, such as large products or products with multiple cores, sand casting, one of the casting methods, is used to produce large products or products with complex shapes. It is very economical to use the method.

This sand casting method is used to manufacture various types of metal parts by injecting molten metal into a mold made of molding sand to obtain a product of the desired shape and then solidifying it.

This is because the process is simple compared to other casting methods, the output is excellent compared to the production input cost, and it has the advantage of being applicable to products of all shapes.

More specifically, the mold for sand casting is composed of molding sand, a binder, and a hardener. The binder serves to combine the molding sand with the molding sand, and the hardener serves to increase the strength of the mold by promoting the bonding.

Here, the mold made of molding sand and binder must have sufficient heat resistance and compressive strength to prevent it from melting and sticking to the surface of the casting when molten metal is injected, which is ultimately directly related to defects in the casting result.

Accordingly, various attempts are being made to provide heat resistance and compressive strength more suitable for the sand casting method by changing or improving the chemical properties of the composition used in the production of molds based on molding sand and binder.

In this regard, Republic of Korea Patent Publication No. 10-1772027 is a prior document on the prior art for improving the characteristics of the mold such as high strength, dimensional stability, and high efficiency by applying an inorganic binder to the molding sand to manufacture a mold for sand casting. “Sand mold casting and dry manufacturing method thereof” (hereinafter referred to as ‘prior art’) has already been presented.

However, in the case of chemical compositions prepared to ensure that existing molds, including the prior art, have sufficient heat resistance and compressive strength, they still do not exhibit sufficient heat resistance to resist high temperature molten metal and are vulnerable to penetration by molten metal. A separate refractory agent is applied to the mold surface to prevent molten metal from penetrating into the mold.

In addition, in the case of chemical compositions prepared to ensure that existing molds, including the prior art, have sufficient heat resistance and compressive strength, there is a problem between the fire retardant and the mold during the process of using the fire retardant due to physical limitations regarding insufficient heat resistance and compressive strength. As ignition or drying for bonding progressed, there was a problem of cracks occurring on the surface of the mold due to insufficient adhesion and heat resistance of the binder connecting the silica sand.

The present invention was created to solve the above problems, and the purpose of the present invention is to have sufficient heat resistance and compressive strength, so that the use of a fire retardant is not necessary in the casting of metal parts through the sand casting method, and that there is no need for the use of a fire retardant in the casting of metal parts through the sand casting method. The goal is to provide a hybrid binder composition that can completely solve the penetration problem.

In order to achieve the above object, the hybrid binder composition for casting metal parts of the present invention includes sand; Binder corresponding to a furan-based organic binder; catalyst; and a filler corresponding to an organic-inorganic hybrid compound, wherein the filler causes a surface modification reaction using a silane coupling agent in TEOS (Tetraethylorthosilicate)-based nano silica to form a hydroxyl compound on the surface. It is prepared from reactive nano silica that has a hydroxy group as a reactive group.

Here, the hybrid binder composition for casting metal parts includes 1000 parts by weight of the sand; 10 parts by weight of the binder; 3 parts by weight of the catalyst; And 0.5 parts by weight of the filler.

In addition, the catalyst includes 1.5 parts by weight of a sulfuric acid-based first catalyst; and 1.5 parts by weight of a hydrochloric acid-based second catalyst.

In addition, the hybrid binder composition for casting metal parts is prepared by mixing 1000 parts by weight of the sand and 0.5 parts by weight of the filler in the first stirring operation, adding 3 parts by weight of the catalyst to the first stirring result, and adding the above to the second stirring result. It can be used for casting metal parts by sequentially performing the third stirring operation by adding 10 parts by weight of binder and 0.3 parts by weight of hardener.

In addition, the hybrid binder composition for casting metal parts has a compressive strength of 35 kgf/cm ² or more (KS A 5301) when used for casting metal parts through sequential stirring from the first stirring operation to the third stirring operation. standard), a heat treatment compressive strength of 30 kgf/cm ² or more (KS A 5301 standard), and a forming hot strength of 85% or more (KS A 5301 standard).

According to the present invention, the following effects are achieved.

First, in forming the mold necessary for casting metal parts through sand casting, the pot life and hardening time can be shortened compared to the existing method, and various physical properties related to heat resistance and compressive strength can be improved to a sophisticated level. A hybrid binder composition for casting can be provided.

Second, when the hybrid binder composition for casting metal parts is used to complete the mold and use it for casting metal parts using the sand casting method, it has sufficient heat resistance to resist high temperature molten metal, allowing penetration of molten metal and silica sand that forms the mold. Mixing problems in cast products can be minimized.

Third, when a mold is completed using a hybrid binder composition for casting metal parts and used for casting metal parts through sand casting, it has sufficient heat resistance to resist high temperature molten metal, making the use of fire retardants unnecessary. The problem of cracks on the surface of the mold that may have occurred during the bonding process between the chemical agent and the mold can be resolved.

Fourth, when the hybrid binder composition for casting metal parts is used to complete the mold and use it for casting metal parts through the sand casting method, problems with cracks in the mold or penetration of molten metal are minimized, improving the use efficiency of the molding sand and improving the casting results. It is possible to improve the quality of metal parts and minimize defects.

Figure 1 is a diagram showing the synthesis method and molecular structure of reactive nano-silica, which is a filler in the hybrid binder composition for casting metal parts according to the present invention.
Figure 2 is a diagram for explaining the form of bonding between a binder and a filler in a hybrid binder composition for casting metal parts according to the present invention through a catalyst.

Preferred embodiments of the present invention will be described in more detail with reference to the attached drawings, but already well-known technical parts will be omitted or compressed for brevity of explanation.

1. Description of hybrid binder composition for casting metal parts

The hybrid binder composition for casting metal parts of the present invention will be described in detail below.

First, the hybrid binder composition for casting metal parts according to the present invention includes sand; Binder; catalyst; And filler; is included in the composition.

Sand is the main material that makes up the mold used for casting metal parts through sand casting, and corresponds to foundry sand.

Such sand has an appropriate content based on 1000 parts by weight.

The binder is a filler corresponding to a furan-based organic binder, and is specifically prepared with furfuryl alcohol, and as shown in Figure 2, cross-linking through a catalyst with the filler to be explained later. It forms and causes bonds between sand particles.

This type of binder is prepared as a furan-based organic binder and serves to form a capillary link between molding sand particles to form cohesion between the particles, and furthermore, through linkage with Reactive Nano Silica, which is a filler. It affects the development of excellent adhesion and high heat resistance.

When combining existing binders through catalysts, there was a significant lack of physical properties in terms of heat resistance and impact strength, and to make up for this, an excessive amount of inorganic filler was required to be used, which caused problems of dispersion and poor adhesion. One point is resolved through the chemical properties of the binder and filler of the present invention.

More specifically, the furan-based organic binder of the present invention prepared with furfuryl alcohol has an appropriate content value of 10 parts by weight, preventing and actually shortening the pot life and curing time compared to the existing ones, and at the same time improving compressive strength. can provide advancement.

In addition, if the furan-based organic binder of the present invention, which is made of furfuryl alcohol, is added in excessive amounts beyond the appropriate content level, curing performance is reduced and the manufacturing of the mold itself is greatly affected.

The catalyst may be a strong acid such as hydrochloric acid, sulfuric acid, or nitric acid, or a weak acid such as acetic acid or phosphoric acid, but it is most preferable to use 1.5 parts by weight of a sulfuric acid-based catalyst and 1.5 parts by weight of a hydrochloric acid-based catalyst in combination.

This shows excellent improvement in compressive strength and hot forming strength when 1.5 parts by weight of a sulfuric acid-based catalyst and 1.5 parts by weight of a hydrochloric acid-based catalyst are combined compared to the use of a specific catalyst alone, especially when a specific catalyst such as a hydrochloric acid-based catalyst is used alone. This is because, unlike the improvement in hot forming strength, there is a decrease in compressive strength properties.

Filler is a filler that corresponds to an organic-inorganic hybrid compound. Specifically, it causes a surface modification reaction using a silane coupling agent on TEOS (Tetraethylorthosilicate)-based nano silica to form hydroxy groups ( It is prepared from reactive nano silica (Hydroxy group) as a reactive group.

In other words, the filler is an organic-inorganic hybrid compound rather than an inorganic filler like existing silica or colloidal silica, and is made into reactive nano silica (Reactive) through a series of processes as shown in Figure 1. It is prepared in the form of Nano Silica.

In the case of existing inorganic fillers, they were applied in a way to improve physical properties by simple mixing, so an excessive amount of 20% to 40% of the resin had to be used. However, while improving strength, there was a problem of deteriorating physical properties related to adhesion. It wasn't resolved.

As an example, the embodiments as presented in "Additives for improving hydrolysis resistance of polyurethane compounds, method of manufacturing same, and polyurethane compositions using the same" in Republic of Korea Patent Publication No. 10-0945300, one of the applicant's previously registered patents. It can be carried out in the same manner as the manufacturing method.

Specifically, as shown in Figure 1, 80 g of tetramethoxysilane and 20 g of bis(trimethoxysilylpropyl)amine were mixed in a 1L two-necked flask and 5 g of 0.1N triethanolamine was added. Then, the reaction was carried out at room temperature for 24 hours at a speed of 100 to 200 rpm to prepare a metal oxide containing an amino group at the terminal and having a network structure of Si-O-Si bonds, and 14.6 g of methylenediphenyl diisocyanate was added to 105 g of the metal oxide. After mixing, 0.1 g of dibutyltin dilaurate was added as a reaction catalyst and stirred for 2 hours in an oil bath at 80°C under a nitrogen atmosphere to produce an isocyanate-terminated organic-inorganic hybrid complex.

As another example, 100 parts by weight of TEOS (Tetraethylorthosilicate) was mixed with 120 parts by weight of Ethanol along with 18 parts by weight of a catalyst of 0.1N HCl or 0.1N triethylamine (TEA), then synthesized for 24 hours at a temperature of 65°C. The solvent is removed, and then an excessive amount of methyl ethyl ketone (MEK) is added, stirred, washed more than 5 times, filtered, and dried at a temperature of 120°C for about 2 hours to reduce the particle size to 50 nm or less. First obtain nano silica in the form of nanoparticles.

Next, the nano-silica obtained in this way is first reacted with a silane coupling agent such as amino-silane and isocyanate to synthesize silane with an isocyanate group. Reactive nano silica is synthesized as an organic-inorganic hybrid composite with a reactive group by reacting with diol and co-hydrolyzing with metal alkoxide.

It is desirable to have an appropriate content of 0.5 parts by weight of reactive nano silica used as such filler.

This is in conjunction with the value of 10 parts by weight of the binder described above, and contains 0.5 parts by weight of reactive nano silica. This does not simply introduce an inorganic filler, but combines reactive nano silica containing a hydroxy group with a furan-based organic binder resin. This not only reduces dispersion defects and improves the strength and heat resistance of the mold, but also shows more advanced improvement in physical properties by using a lower amount than the existing binder.

In an actual experiment, if there is a discrepancy in the ratio between the appropriate content of 10 parts by weight of binder and 0.5 parts by weight of reactive nano silica, the physical properties of compressive strength and hot forming strength do not differ significantly or are lowered compared to the existing ones. Depending on this, a problem occurred where the pot life and curing time increased significantly.

In other words, the reactive nano silica used as a filler reacts with the binder according to the appropriate content value as shown in Figure 2, causing cross-linking through a catalyst, so the adhesive properties and physical strength caused by the binder are further improved. It strengthens and connects the binders to improve heat resistance and durability.

As a result, a Furan/Silica hybrid binder type composite is completed, forming a stronger and more systematic bond and hardening with the sand particles corresponding to the molding sand.

In the hybrid binder composition for casting metal parts of this composition, it is also important to follow the order of performing three rounds of stirring when mixing the compositions. Specifically, 1000 parts by weight of sand and 0.5 parts by weight of filler are mixed in the first stirring operation and the first stirring operation. 3 parts by weight of catalyst (1.5 parts by weight of sulfuric acid-based first catalyst, 1.5 parts by weight of hydrochloric acid-based second catalyst) were added to the stirring result for secondary stirring, and 10 parts by weight of binder and 0.3 parts by weight of hardener were added to the secondary stirring result. It is preferable to sequentially perform the third stirring operation and use it for casting metal parts.

This is because if you change the order of the first to third stages of the stirring sequence or change the object of stirring, the results of the catalytic reaction will rapidly deteriorate, or the physical properties related to heat resistance and extrusion strength of the resultant product prepared through the reaction will deteriorate. .

2. Description of physical property test results of hybrid binder composition for casting metal parts

The level of various physical properties of the hybrid binder composition for casting metal parts according to the present invention was measured through various experimental methods as follows, and the following experiments were conducted for the purpose of defining the properties by means that are obvious to those skilled in the art. methods were used.

(1) Physical property test method

First, for all examples described below, tests were conducted on compressive strength, compressive strength after heat treatment, and hot forming strength ratio along with measurement of pot life and curing time. In particular, the compressive strength was measured in two rounds. Repeated experiments were performed.

- Compressive strength and heat treatment compressive strength

A test specimen was produced according to the KS A 5301 test standard and a compressive strength test was conducted, and the specimen standard was '50×50 (Ø×m, AFS. 20-40).'

- Forming hot strength

A test piece was manufactured according to the KS A 5301 test standard, and the compressive strength was evaluated after heat treatment (250℃, 10 minutes) to calculate the compressive strength retention rate compared to the room temperature measurement value. The specimen size was '50×50(Ø×m, AFS. 20-40)'.

(2) Evaluation of physical properties according to changes in composition and content level of hybrid binder composition for casting metal parts

In Example 1, the composition consisted of only sand, binder (furfuryl alcohol), and a sulfuric acid-based catalyst.

In Examples 2 and 3, sand, binder (furfuryl alcohol), sulfuric acid catalyst, and hydrochloric acid catalyst were added to the composition, and an inorganic filler, silica (product example: Zeosil 175mp (solid content: 100%)) ) was added, but each content was different.

In Examples 4 and 5, in the composition of sand, binder (Furfuryl alcohol), sulfuric acid catalyst, and hydrochloric acid catalyst, an inorganic filler, colloidal silicate, product example: F-4562 (solid content) : 40%)) was added, but each content was different.

In Examples 6 and 7, Reactive Nano Silica, an organic-inorganic hybrid compound, was added to the composition of sand, binder (furfuryl alcohol), sulfuric acid catalyst, and hydrochloric acid catalyst as a filler. However, the contents of each were different.

The specific composition and content values of Examples 1 to 7 are summarized in Table 1 below.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 sand 1000g 1000g 1000g 1000g 1000g 1000g 1000g bookbinder 10g 10g 10g 10g 10g 10g 10g catalyst
(sulfuric acid) 3g 1.5g 1.5g 1.5g 1.5g 1.5g 1.5g catalyst
(hydrochloric acid) - 1.5g 1.5g 1.5g 1.5g 1.5g 1.5g silica - 0.5g 0.8g - - - - colloidal
silica - - - 1.25g 2g - - Responsive
silica - - - - - 0.5g 0.8g

For Examples 1 to 7 prepared in this way, tests were performed on compressive strength, compressive strength after heat treatment, and hot forming strength ratio along with measurement of pot life and curing time. In particular, the compressive strength was measured twice. Repeated experiments were performed, and the results are shown in Table 2 below.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 pot life 5 minutes 10 seconds 5 minutes 10 seconds 5 minutes 40 seconds 5 minutes 5 minutes and 30 seconds 4 minutes 50 seconds 5 minutes 20 seconds curing time 9 minutes 50 seconds 8 minutes 20 seconds 10 minutes 10 seconds 8 minutes 30 seconds 9 minutes 10 seconds 7 minutes 20 seconds 8 minutes 10 seconds compressive strength
(kgf/ ^cm2 ) 28.44 30.62 28.72 30.25 30.11 35.86 32.69 27.73 31.07 29.02 31.12 28.77 35.77 31.87 heat treatment
compressive strength
(kgf/ ^cm2 ) 23.21 27.29 24.25 26.17 25.21 32.49 27.14 17.64 26.98 22.42 27.29 24.58 31.54 26.94 hot plastic surgery
robbery(%) 73 78 75 81 79 89 84

As shown in Table 2, compared to the existing method such as Example 1, when silica was used as an inorganic filler in Examples 2 and 3, the level of improvement in physical properties in terms of compressive strength and hot forming strength was minimal. It can be seen that the pot life remains the same or rather increases, and the curing time also increases as the content increases.

In addition, compared to Example 1, when colloidal silicate was used as an inorganic filler in Examples 4 and 5, the improvement in compressive strength and hot forming strength was only minimal, and the pot life and hardening were limited. It can be seen that the time actually increases as the content increases.

On the other hand, compared to Example 1, when reactive nano silica, an organic-inorganic hybrid compound, was used as a filler in Examples 6 and 7, the level of improvement in physical properties in terms of compressive strength and hot forming strength was significantly improved. It can be seen that it has a compressive strength of over 35 kgf/cm ² (based on KS A 5301), a heat-treated compressive strength of over 30 kgf/cm ² (based on KS A 5301), and a hot forming strength of over 85% (based on KS A 5301).

In particular, when the appropriate content values for each composition are maintained as in Example 6, the pot life and curing time are also significantly reduced.

The embodiments disclosed in the present invention are not intended to limit but illustrate the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by these examples. The scope of protection should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

Claims (5)

sand;
Binder corresponding to a furan-based organic binder;
catalyst; and
Includes a filler corresponding to an organic-inorganic hybrid compound,
The filler undergoes a surface modification reaction using a silane coupling agent on TEOS (Tetraethylorthosilicate)-based nano silica to form reactive nano silica with a hydroxy group on the surface. Characterized by being provided
Hybrid binder composition for casting metal parts.
According to paragraph 1,
The hybrid binder composition for casting metal parts,
1000 parts by weight of the sand;
10 parts by weight of the binder;
3 parts by weight of the catalyst; and
Characterized in that it contains 0.5 parts by weight of the filler.
Hybrid binder composition for casting metal parts.
According to paragraph 2,
The catalyst is,
1.5 parts by weight of a sulfuric acid-based first catalyst; and
Characterized by comprising 1.5 parts by weight of a hydrochloric acid-based second catalyst;
Hybrid binder composition for casting metal parts.
According to paragraph 2,
The hybrid binder composition for casting metal parts is prepared by first stirring 1000 parts by weight of the sand and 0.5 parts by weight of the filler, adding 3 parts by weight of the catalyst to the result of the first stirring, and adding 10 parts by weight of the binder to the result of the second stirring. Characterized in that it is used for casting metal parts by sequentially performing a 3rd stirring operation by adding 0.3 parts by weight and hardener.
Hybrid binder composition for casting metal parts.
According to paragraph 4,
The hybrid binder composition for casting metal parts has a compressive strength of 35 kgf/cm ² or more (based on KS A 5301) when used for casting metal parts through sequential stirring from the first stirring operation to the third stirring operation. , Characterized by having a heat treatment compressive strength of more than 30 kgf/cm ² (based on KS A 5301) and a hot forming strength of more than 85% (based on KS A 5301).
Hybrid binder composition for casting metal parts.