A water-based curing agent for casting sand mold 3D printing and its preparation method and application

Abstract

The present invention is a water-based curing agent for casting sand mold 3D printing and its preparation method and application, and specifically relates to the field of casting sand mold 3D printing technology. A water-based curing agent for casting sand mold 3D printing, the water-based curing agent for casting sand mold 3D printing is prepared by mixing copper chloride, organic phenol sulfonic acid, benzene sulfonic acid and diluent, and the total acid value of the water-based curing agent for casting sand mold 3D printing is 25%-40% in terms of sulfuric acid. In the process of sand mold 3D printing, the present invention reduces the pungent odor emitted by alcohol solvents, increases the environmental friendliness of the workshop, is conducive to reducing the gas emission of sand molds, and is suitable for precision and complex castings and complex sand mold 3D printing. The water-based curing agent for 3D printing not only meets the requirements of 3D printing equipment for the physical and chemical performance indicators of the curing agent, but also meets the requirements for the production and application of precision and complex castings in terms of casting process performance such as bonding strength, curing speed, and sand mold gas emission.

Description

Technical Field

[0001] The present invention belongs to the technical field of foundry sand mold 3D printing, and specifically relates to a water-based curing agent for foundry sand mold 3D printing, and a preparation method and application thereof. Background Art

[0002] In sand mold 3D printing, considering various factors such as cost, process, and performance, furan resin is currently the most widely used binder. The performance and quality of 3D printed sand molds are not only related to the performance of furan resin, but also to the curing agent system used with furan resin. Therefore, it is very necessary to study the curing behavior of different curing systems and select a curing agent system with high cost performance and easy to adjust the curing speed.

[0003] In the process of 3D printing of casting sand molds, the sand spreader spreads a layer of silica sand, the print head sprays furan resin binder at the designed position, the sand box drops to a certain height, and then continues to spread sand and spray binder, repeating the process until the sand mold printing is completed. The time interval between two sand spreading is about ten seconds, so the curing agent is required to have high activity, can be quickly cured, reach a certain initial strength, and be able to support the subsequent sand spreading process, ensure that the sand mold does not deform, and maintain dimensional accuracy.

[0004] The curing agent used in conjunction with furan resin in the current casting sand mold 3D printing process is mainly ditoluene sulfonic acid alcohol-based curing agent, and the use of alcohol-based curing agent can better adapt to changes in ambient temperature and humidity. However, in the 3D printing process, when using alcohol-based curing agent, the curing agent usually contains more methanol, which is not only flammable, but also easy to release irritating odor, directly deteriorating the environment of the casting 3D printing workshop, affecting the health of the operators, and, considering the price, the price of alcohol-based curing agent is relatively high. In the current casting sand mold 3D printing market, competition is intensifying and the general pursuit of cost-effectiveness is under the situation. The high curing agent price has hindered market promotion to a certain extent. Based on these two problems, the present application proposes a 3D printing water-based curing agent and a preparation method thereof. Summary of the invention

[0005] The purpose of the present invention is to provide a water-based curing agent for 3D printing of foundry sand molds and its preparation method and application. In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] A water-based curing agent for 3D printing of foundry sand molds is prepared by mixing cupric chloride, organic phenol sulfonic acid, benzene sulfonic acid and a diluent. The total acid value of the water-based curing agent for 3D printing of foundry sand molds is 25%-40% in terms of sulfuric acid. The water-based curing agent for 3D printing of foundry sand molds is composed of 5 to 15 parts of cupric chloride, 60 to 80 parts of organic phenol sulfonic acid, 5 to 10 parts of benzene sulfonic acid and 40 to 60 parts of diluent in parts by weight.

[0007] Furthermore, the organic phenol sulfonic acid is a product generated by the reaction of sulfuric acid, xylene and phenol; the sulfuric acid is concentrated sulfuric acid with a concentration of 98%; the xylene is a mixture of p-xylene, m-xylene and o-xylene, and the weight ratio of p-xylene:m-xylene:o-xylene in the mixture is 2:7:1.

[0008] Furthermore, the diluent is a mixture of ethanol and water, and the ethanol and water are mixed in a weight ratio of 1:9.

[0009] Furthermore, a method for preparing a water-based curing agent for 3D printing of foundry sand molds is provided, wherein the preparation of the water-based curing agent for 3D printing of foundry sand molds comprises the following steps:

[0010] Step 1: preparing organic phenol sulfonic acid: according to weight parts, add 10 to 30 parts of xylene and 20 to 40 parts of sulfuric acid into a reaction kettle, heat at a rate of less than 1°C / min, and keep warm at 130°C to 150°C for 90 minutes to 150 minutes; add 10 to 20 parts of phenol, and keep warm at 120°C to 130°C for 30 to 60 minutes;

[0011] Step 2: Cool down to 60°C, add 40 to 60 parts of diluent, heat up to 90 to 100°C, and keep warm for 30 to 60 minutes;

[0012] Step 3: Cool down to 60°C, add 5 to 15 parts of copper chloride and 5 to 10 parts of benzenesulfonic acid;

[0013] Step 4: Cool down to below 40℃, discharge and set aside.

[0014] Furthermore, an application of a water-based curing agent for 3D printing of foundry sand molds is provided, wherein the water-based curing agent for 3D printing of foundry sand molds is used in combination with a furan resin for 3D printing of foundry sand molds. When used, the amount of the water-based curing agent added for 3D printing of foundry sand molds is 20wt.%-30wt.% of the amount of the furan resin added for 3D printing of foundry sand molds.

[0015] The beneficial effects of the present invention are:

[0016] 1. The solvent of water-based curing agent used in 3D printing is mainly water. In the process of sand mold 3D printing, it can reduce the pungent smell of alcohol solvents and increase the environmental friendliness of the workshop;

[0017] 2. The amount of water-based curing agent added for 3D printing is generally 20 wt.% to 30 wt.% of the amount of furan resin added. Compared with the traditional self-hardening furan resin sulfonic acid curing agent, the amount added is greatly reduced, which is beneficial to reduce the gas emission of sand molds, and is especially suitable for precision and complex castings;

[0018] 3. Under the condition of low addition amount of water-based curing agent for 3D printing, the curing agent has high activity and fast curing speed, which can make the 3D printed furan resin sand mold have good hardening characteristics, high sand mold strength (bending strength above 5.0MPa), low gas emission (gas emission less than 10.0ml / g at 1000℃), especially suitable for complex sand mold 3D printing. The water-based curing agent for 3D printing not only meets the physical and chemical performance index requirements of the curing agent for 3D printing equipment, but also meets the production and application requirements of precision complex castings in terms of casting process performance such as bonding strength, curing speed, and sand mold gas emission. DETAILED DESCRIPTION

[0019] The preparation method of the present invention is described in detail below. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. The parts of the present invention are measured by weight.

[0020] Example 1

[0021] 1) Preparation of organic phenol sulfonic acid: the organic phenol sulfonic acid is a product generated by the reaction of sulfuric acid, xylene and phenol; the sulfuric acid is concentrated sulfuric acid with a concentration of 98%; the xylene is a mixture of p-xylene, m-xylene and o-xylene, p-xylene: m-xylene: o-xylene in the mixture are mixed in a weight ratio of 2:7:1, 25 parts are taken out and added together with 20 parts of sulfuric acid into a reactor, the temperature is increased at a rate of less than 1°C / min, and the temperature is kept at 150°C for 150 minutes; 15 parts of phenol are added, and the temperature is kept at 120°C for 60 minutes; 60 parts of organic phenol sulfonic acid are obtained;

[0022] 2) Cool down to 60°C, add 40 parts of a diluent made of ethanol and water in a weight ratio of 1:9, heat up to 90°C~100°C, and keep warm for 30 minutes;

[0023] 3) Cool down to 60°C and add 15 parts of copper chloride and 10 parts of benzenesulfonic acid;

[0024] 4) Cool down to below 40°C, discharge the material, and measure the total acid value of the curing agent (calculated as sulfuric acid) to be 25.7%, and the free sulfuric acid content to be 2.6%.

[0025] Example 2

[0026] 1) Preparation of organic phenol sulfonic acid: the organic phenol sulfonic acid is a product generated by the reaction of sulfuric acid, xylene and phenol; the sulfuric acid is concentrated sulfuric acid with a concentration of 98%; the xylene is a mixture of p-xylene, m-xylene and o-xylene, p-xylene: m-xylene: o-xylene in the mixture are mixed in a weight ratio of 2:7:1, 30 parts of the mixture are added together with 40 parts of sulfuric acid into a reactor, the temperature is increased at a rate of less than 1°C / min, and the temperature is kept at 140°C for 120 minutes; 10 parts of phenol are added, and the temperature is kept at 120°C for 45 minutes; 80 parts of organic phenol sulfonic acid are obtained;

[0027] 2) Cool down to 60℃, add 50 parts of diluent made of ethanol and water in a weight ratio of 1:9, heat up to 90℃~100℃, and keep warm for 30 minutes;

[0028] 3) Cool down to 60°C, add 10 parts of copper chloride and 7.5 parts of benzenesulfonic acid;

[0029] 4) Cool down to below 40°C, discharge the material, and measure the total acid value of the curing agent (calculated as sulfuric acid) to be 33.2%, and the free sulfuric acid content to be 3.4%.

[0030] Example 3

[0031] 1) Preparation of organic phenol sulfonic acid: the organic phenol sulfonic acid is a product generated by the reaction of sulfuric acid, xylene and phenol; the sulfuric acid is concentrated sulfuric acid with a concentration of 98%; the xylene is a mixture of p-xylene, m-xylene and o-xylene, and p-xylene: m-xylene: o-xylene in the mixture are mixed in a weight ratio of 2:7:1, 10 parts are taken out and added together with 35 parts of sulfuric acid into a reactor, the temperature is increased at a rate of less than 1°C / min, and the temperature is kept at 130°C for 90 minutes; 20 parts of phenol are added, and the temperature is kept at 130°C for 60 minutes; 65 parts of organic phenol sulfonic acid are obtained;

[0032] 2) Cool down to 60°C, add 60 parts of a diluent made of ethanol and water in a weight ratio of 1:9, heat up to 90°C~100°C, and keep warm for 60 minutes;

[0033] 3) Cool down to 60°C, add 5 parts of copper chloride and 5 parts of benzenesulfonic acid;

[0034] 4) Cool down to below 40°C, discharge the material, and measure the total acid value of the curing agent (calculated as sulfuric acid) to be 38.4%, and the free sulfuric acid content to be 4.8%.

[0035] Comparative Example 1

[0036] 1) Add 70 parts of xylene (p-xylene: m-xylene: o-xylene in a weight ratio of 2:7:1) and 60 parts of sulfuric acid into a reactor, raise the temperature at a rate of less than 1°C / min, and keep the temperature at 110°C~120°C for 120 minutes;

[0037] 2) Cool down to 90°C, distill under reduced pressure, and the vacuum degree is -0.06MPa, and 10 parts of xylene are obtained after removal;

[0038] 3) Cool down to 40°C, add 15 parts of methanol, stir evenly, and discharge the material after cooling. The total acid value of the curing agent (calculated as sulfuric acid) is measured to be 35.2%, and the free sulfuric acid content is 6.3%.

[0039] Performance test: 20 kg of raw sand was taken, and the water-based curing agent for casting sand mold 3D printing was used in combination with the furan resin for casting sand mold 3D printing. When used, the amount of water-based curing agent added for casting sand mold 3D printing was 20 wt.%-30 wt.% of the amount of furan resin added for casting sand mold 3D printing (see Table 1). After mixing for 120 seconds, the sand was prepared for use. After 24 hours, a standard "8"-shaped sample was prepared using a VX200 3D printer. The amount of furan resin added accounted for 1.2% of the weight of the sand. The prepared sample was kept at 80℃-85℃ for 60 minutes, cooled to room temperature, and the tensile strength of the sample was measured using an intelligent sand strength tester, and the gas emission was measured using an intelligent molding material gas emission tester. From the test results, the 3D printing curing agent of the present invention has lower free sulfuric acid than ordinary curing agents when the acid value is similar, and the addition amount is about half of that of the ordinary curing agent to meet the use requirements. At a lower addition amount, the printed sand mold has higher bonding strength and lower gas evolution, and is particularly suitable for printing complex precision casting sand molds.

[0040] Table 1 3D printed sample performance test results

[0041]

[0042] Matters not covered by the present invention are known technologies.

[0043] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A water-based curing agent for casting sand mold 3D printing, characterized in that: The water-based curing agent for 3D printing of foundry sand molds is prepared by mixing copper chloride, organic phenol sulfonic acid, benzene sulfonic acid and a diluent, and the total acid value of the water-based curing agent for 3D printing of foundry sand molds is 25%-40% in terms of sulfuric acid; the water-based curing agent for 3D printing of foundry sand molds is composed of: 5 to 15 parts of copper chloride, 60 to 80 parts of organic phenol sulfonic acid, 5 to 10 parts of benzene sulfonic acid, and 40 to 60 parts of diluent; the organic phenol sulfonic acid is a product generated by the reaction of sulfuric acid, xylene and phenol; The sulfuric acid is concentrated sulfuric acid with a concentration of 98%; the xylene is a mixture of p-xylene, m-xylene and o-xylene, and the weight ratio of p-xylene: m-xylene: o-xylene in the mixture is 2:7:1; The method for preparing a water-based curing agent for 3D printing of foundry sand molds comprises the following steps: Step 1: preparing organic phenol sulfonic acid: according to weight parts, 10 to 30 parts of xylene and 20 to 40 parts of sulfuric acid are added into a reaction kettle, the temperature is increased at a rate of less than 1°C / min, and the temperature is kept at 130°C to 150°C for 90 minutes to 150 minutes; 10 to 20 parts of phenol are added, and the temperature is kept at 120°C to 130°C for 30 minutes to 60 minutes; Step 2: Cool down to 60°C, add 40 to 60 parts of diluent, heat up to 90 to 100°C, and keep warm for 30 to 60 minutes; Step 3: Cool down to 60°C, add 5 to 15 parts of copper chloride and 5 to 10 parts of benzenesulfonic acid; Step 4: Cool down to below 40°C, discharge and set aside; The diluent is a mixture of ethanol and water, and the ethanol and water are mixed in a weight ratio of 1:

9.

2. An application of a water-based curing agent for 3D printing of foundry sand molds, using the water-based curing agent for 3D printing of foundry sand molds as claimed in claim 1, characterized in that: The water-based curing agent for 3D printing of foundry sand molds is used in combination with furan resin for 3D printing of foundry sand molds. When used, the amount of the water-based curing agent added for 3D printing of foundry sand molds is 20 wt.%-30 wt.% of the amount of furan resin added for 3D printing of foundry sand molds.

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