JPS61169131A - Surface hardener for simple pattern - Google Patents

Abstract

PURPOSE:To improve the surface hardeness of a simple pattern and to prevent the deformation and failure of the pattern during molding of a casting mold by limiting the compounding ratio of an epoxy resin, modified aliphat. polyamine and resin gypsum. CONSTITUTION:The surface hardener is the pasty material obtd. by mixing 2-10pts.wt. modified aliphat. polyamine and 1-10pts.wt. resin gypsum with 10pts.wt. epoxy resin. The compounding ratio of the resin gypsum is changed within the above-mentioned range and water and other solvents are not used at all to adjust viscosity. The surface hardener is prepd. by mixing the epoxy resin and modified aliphat. polyamine then adding and mixing the resin gypsum to and with the mixture composed thereof.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a surface hardening agent for simple models.

[Conventional technology]

Metal molds, resin molds, and wooden molds are used as materials for casting models, but when the number of pieces produced is small, foamed polystyrene is used as a substitute for the wooden mold in order to reduce model material costs and processing costs. A simple model using etc. (hereinafter referred to as a simple model)
may be used.

Compared to foamed polystyrene and wood, it has the advantage of being cheaper, more flexible, and easier to work with, but it is too soft to be used as a model material, so it tends to deform or break when making molds. It has some drawbacks. Furthermore, as a characteristic of polystyrene foam, there are concave portions on the finished surface of the model, which has the disadvantage of worsening the casting surface of the casting.

In order to improve these drawbacks, various means for hardening the surface of the simple model have been considered, but no surface hardening agent that is effective in terms of practical aspects including paintability, repeatability, etc. has yet to be found.

[Problem that the invention seeks to solve]

The purpose of the present invention is to improve the surface hardening of the simple model in order to put it into practical use, eliminate troubles caused by deformation and breakage of the model during mold making, and enable the model to be used repeatedly. Another object of the present invention is to provide a surface hardening agent.

[Means for solving problems]

The present invention relates to a surface hardening agent for simple models, which is made by mixing 2 to 10 parts by weight of a modified aliphatic polyamine and 1 to 10 parts by weight of resin plaster to 10 parts by weight of an epoxy resin.

That is, the surface hardening agent of the present invention is characterized in that it utilizes resin gypsum, which is originally hardened by mixing with water, as an auxiliary additive for epoxy resin. This improves the hardness of the resin.

In the present invention, 2 to 10 parts by weight of modified aliphatic polyamine and 1 to 1 part by weight of resin gypsum are added to 10 parts by weight of epoxy resin.
Although 0 parts by weight is mixed, an appropriate mixture is selected within this range depending on various conditions such as the shape and size of the target model, curing conditions, and required hardness. If the amount of the modified aliphatic polyamine and resin gypsum is less than the above range, there may be disadvantages such as the curing of the surface hardening agent of the present invention becomes extremely slow or the required hardness cannot be obtained, or vice versa. If the amount exceeds the above range, problems such as extremely poor workability and peeling of the hardened surface layer will occur.

The 'modified aliphatic polyamine in the present invention is one having an action as a curing agent, such as HPOXY TIJARD NERsx 900 manufactured by Obe Sangyo Co., Ltd.
FB (Amine value 530-380. Viscosity 3-7PS
/25°C liquid) etc. are used.

In addition, the resin plaster in the present invention is a mixture of industrial model river plaster with a resin such as melamine in order to improve the workability, strength, and hardness of the industrial model river plaster. For example, Nitto Seki IF (
Product name: NITTOPEARL 5TONI manufactured by Co., Ltd.
n-11 (a mixture of melamine resin and gypsum), etc. are used.

In addition, the epoxy resin in the present invention is, for example, Adeka Resin BP4520 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.) (epoxy equivalent: 192 to 215, specific gravity: 1.11 to 1.13,
A liquid with a viscosity of 8 to 12 Ps/25°C) is used.

The surface hardening agent of the present invention is a paste obtained by mixing only the above-mentioned epoxy resin, modified aliphatic polyamine, and resin gypsum in the above-mentioned amounts. The blending amount is varied within the above range, and water and other solvents are not used at all. The surface hardening agent of the present invention is prepared by mixing an epoxy resin and a modified aliphatic polyamine, and then adding and mixing resin gypsum.

When using the surface hardening agent of the present invention, after producing a simple model, the surface hardening agent is applied to the surface of the model to complete the model. Apply the surface hardening agent of the present invention to the surface of the simple model, for example, by applying 0.1
When applied to a thickness of more than 10 times, a hard hardened layer is formed after 1 to 4 hours.

〔Effect of the invention〕

In the case of a simple model that is not coated with the surface hardening agent of the present invention, it is easily deformed by denting when pressed with a fingertip. Furthermore, in the case of conventional surface hardening agents, the surface hardness is too low, causing deformation and damage to the model during molding, and the number of times of repeated use is about 1 to 2 times.

On the other hand, the surface hardening agent of the present invention does not fall off from the simple model at all due to the improvement in surface hardness due to the addition of resin gypsum and the adhesive strength and toughness of the epoxy resin, and also prevents deformation of the simple model during mold making. No damage is detected.

Furthermore, if the surface hardening agent of the present invention is used, the simple model can be used repeatedly about 1 to 20 times, so the range of application can be expanded, and as a result, a significant reduction in model material costs and model processing costs can be realized.

〔Example〕

The surface hardening agent of the present invention having the composition shown in the table below was applied with a brush to one side of 50 test pieces made of expanded polystyrene (specific gravity 18 I/z), cage width x 100 mm length x somm thickness, and the surface hardness after 24 hours was measured as a raw mold grade. Measured using a mold hardness meter, and the number of measurements (n
) The average value (X) and standard deviation (δn-t
) are shown in Table 1.

For reference, the surface hardness was also measured when a surface hardening agent containing no resin gypsum was applied and when no surface hardening agent was applied, and the results are also shown in Table 1.

In addition, in the two-coat cases in the table below, the second coat was applied after the first coat was completed, and the hardness was measured 24 hours later.

As is clear from the above table, the surface hardness of the material without surface hardening agent applied (i.e., expanded polystyrene itself) is
o, 6, and if a comparative surface hardening agent (i.e., epoxy resin) is applied, it becomes i 9 [1,4, and the hardness of the surface layer is considerably improved. However, with this level of improvement, the model is not suitable for practical use. deformation or damage cannot be prevented.

In contrast, the surface hardening agent of the present invention exhibits a surface hardness of iq 4.7, which not only prevents deformation and damage of the model, but also prevents peeling and damage of the hardened layer during molding or handling. 0 Sub-agents 1) Clearance agent Ryo Hagiwara −

Claims (1)

[Claims] A surface hardening agent for simple models, characterized in that it is made by mixing 2 to 10 parts by weight of a modified aliphatic polyamine and 1 to 10 parts by weight of resin gypsum to 10 parts by weight of an epoxy resin.