JPH02378B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a material for a master model. A master model is, for example, a prototype model created when designing a mechanical device, a part, etc. When creating a master model, a block-shaped or plate-shaped material is formed by cutting, drilling, grinding, etc., and is then created as a prototype model. It is what you do. Therefore, such materials are required to have excellent dimensional stability and workability. In particular, with regard to workability, it is necessary that the material can be processed freely and easily using ordinary tools such as a chisel, knife, planer, file, drill, lathe, etc. Traditionally, wood with excellent dimensional stability has generally been used as a material for such master models, but in recent years, high quality and homogeneous natural wood has become difficult to obtain.
In addition, there are other problems such as the need for long-term aging and natural drying in order to obtain good dimensional stability. On the other hand, attempts have been made to use synthetic resins or synthetic resin foams as materials for master models, but they have insufficient dimensional stability and thermal stability, and are significantly inferior in workability and toughness. ,
I haven't been able to find anything that surpasses wood. The present inventors have conducted intensive research in view of the above-mentioned problems when applying existing synthetic resins or synthetic resin foams as materials for master models.
The present invention has been completed, and its purpose is to provide a method for manufacturing a material for a master model that has excellent dimensional stability, thermal stability, workability, and toughness. For the above purpose, 1 part by weight of resol type phenolic resin prepolymer, 0.02 part of polyvinyl alcohol
~0.2 parts by weight, a pore-forming agent, and an aldehyde are reacted in the presence of an acid catalyst to precure, and then the precured product is washed with water and dried, and then heated and cured to produce a porous structure having a network of continuous pores. This is achieved by a method for manufacturing a master model material characterized by the following. What is important in the present invention is that polyvinyl alcohol is mixed and reacted with a resol type phenolic resin prepolymer (hereinafter referred to as resol resin) to form a porous body structure having continuous pores.
The amount of polyvinyl alcohol mixed with the resol resin is 0.02 parts by weight of the resol resin.
~0.2 part by weight is required. If the amount of polyvinyl alcohol relative to the resol resin is less than 0.02 parts by weight, it will become brittle, resulting in poor processability.
It lacks toughness, and if it exceeds 0.2 parts by weight, dimensional stability will be poor. When the average pore diameter of the master model material obtained by the method of the present invention is in the range of 0.5 to 50 microns, it has a fine texture and is suitable as a master model material that requires precision. Further, a porosity of 40 to 90% is suitable in terms of workability and strength during advanced processing. The resol resin used in the present invention is water-soluble,
It is an initial product produced by reacting phenols with aldehydes in the presence of a basic catalyst, and generally contains 1.5 to 3.5 moles of aldehyde per mole of phenol in the presence of a slight excess of an alkaline catalyst. By keeping the initial condensate reacted below in a stable water-soluble state, a water-soluble resol resin can be obtained. Phenols used in the production of resol resins most commonly include phenols and cresols. However, other phenols can also be used, such as phenol, 0-cresol, m-cresol, p-cresol, 2,3-xylenol,
2,5-xylenol, 2,4-xylenol,
2,6-xylenol, 3,4-xylenol,
3,5-xylenol, o-ethylphenol,
m-ethylphenol, p-ethylphenol,
Examples include p-phenylphenol, p-tert-butylphenol, p-tert-aminophenol, bisphenol A, resorcinol, and mixtures of these phenols. Formaldehyde is the most common aldehyde used for polycondensation with this phenol. However, monoaldehydes and dialdehydes such as paraformaldehyde, hexamethylenetetramine, furfural and glutaraldehyde, adipaldehyde and glyoxal may also be used. As the basic catalyst used in the resol resin synthesis reaction, known catalysts such as caustic alkali, alkali carbonate, barium hydroxide, calcium hydroxide, ammonia, quaternary ammonium compounds, and amines may be used. is most commonly used. The polyvinyl alcohol used in the present invention is generally obtained by saponifying vinyl acetate, and
There are no particular restrictions on its degree of polymerization, degree of saponification, branching, copolymerization with other monomers, etc., and it can be used alone or in combination of two or more, but preferably has a degree of polymerization of 100.
~5000, preferably with a saponification degree of 70% or more. The acid catalyst used in the present invention includes hydrochloric acid, sulfuric acid,
Oxalic acid, lactic acid, formic acid, acetic acid, para-toluenesulfonic acid, benzenesulfonic acid, etc. are suitable. The amount of the acid catalyst to be added may be appropriately determined in consideration of the type of catalyst used, raw material composition, curing temperature, etc. In the present invention, it is more effective to appropriately incorporate organic or inorganic substances for the purpose of improving strength, toughness, processability, preventing oxidation, coloring, and even increasing the amount. Organic substances added for the purpose of improving strength, toughness, and processability include liquid or aqueous polymers or their precursors, such as melamine resins, epoxy resins, urethane resins or their precursors, and granules and powders. Examples include fine powders of synthetic resin powder, wood, pulp, synthetic fibers or natural fibers. In particular, when a reactive granular or powdery phenolic resin is used for the purpose of improving strength, the effect is remarkable. Reactive granular or powdered phenolic resin is completely different from pulverized cured products of conventionally known resol resins or cured novolak resins, or pulverized cured novolak resin fibers. This is a phenolic resin made of spherical primary particles and secondary aggregates thereof, which is manufactured according to the manufacturing method described in JP-A-57-177011. Since this reactive granular or powdered phenolic resin has a nearly spherical shape, it is easier to mix with polyvinyl alcohol or liquid phenolic resin than powder obtained by pulverizing known cured phenolic resins. By using this resin, a high-strength phenolic resin porous body having continuous pores in which a large amount of phenolic resin powder is uniformly mixed can be obtained. Examples of organic substances added for the purpose of preventing oxidation include substances that suppress oxidation during heat treatment, heat accumulation phenomenon, and so-called panking phenomenon, such as phenol compounds,
Examples include hindered phenol compounds, amine compounds, hydroxylamine compounds, and ultraviolet absorbers that suppress deterioration due to aging. In addition, phthalate esters are used to increase viscoelasticity.
Alternatively, it is effective to add a small amount of a general plasticizer such as a phosphate ester type plasticizer, but depending on the amount added, it may bleed out or impair dimensional stability, so this must be done carefully. There is. Examples of inorganic substances include salts such as calcium carbonate, mirabilite, and calcium sulfate, glass powder or glass fiber powder, asbestos, asbestos, mica, powders or whiskers of metals and their oxides, etc. It is used as an agent or a reinforcing agent. 1 of the manufacturing method of the master model material of the present invention
Examples are as follows. First, in a mixture of a predetermined amount of liquid resol resin and an aqueous polyvinyl alcohol solution, an aqueous dispersion of a commonly used pore-forming agent such as starch or modified starch, a crosslinking agent for polyvinyl alcohol such as aldehydes, acids, etc. Add the required amount of each and stir and mix uniformly to obtain a reaction stock solution. When adding other additives, add appropriate amounts to this reaction stock solution. Next, pour the above reaction stock solution into a mold, etc., and heat it at 40 to 80℃.
After precuring by heating at 100 to 200°C for 10 to 20 hours, the product is washed with water and dried, and cured at 100 to 200°C for 10 to 30 hours to complete the curing reaction. The above-mentioned pre-cured product is not an elastic body but a brittle cured body, and is usually white if no coloring additive is added. On the other hand, the cured product after curing is a hard porous body, and usually exhibits a yellow color when no coloring additive is added. The material manufactured in this way into an appropriate shape such as a block or plate can be processed using ordinary tools such as a chisel, plane, knife, file, drill, lathe, etc., or by using machining methods such as NC processing. Finish into the specified shape. The master model material obtained by the method of the present invention has good workability without phenomena such as "chips", "cracks", and "stains" caused by processing tools. Furthermore, the dimensional stability after processing is good, and so-called "misalignment" is small. One of its major features is that it does not suffer from deformation or deterioration caused by heating, which is the case with resin-based materials. Furthermore, since it has no directionality compared to wood, it can be processed in various directions. The present invention will be specifically described below with reference to Examples. Example 1 Resol resin aqueous solution (PR961A manufactured by Sumitomo Durez)
Solid content: 64%) and polyvinyl alcohol (manufactured by Kuraray)
PVA117) and the total weight of solids is approximately the total volume.
They were mixed at the ratio shown in Table 1 so that the ratio was 30 W/V% (approximately 3 kg for a total volume of 10). Furthermore, 5W/V% of horse yam starch, which is a pore-forming agent, was steamed in advance and thoroughly kneaded into the above-mentioned mixture of PVA and resol resin aqueous solution, and used as a cross-linking agent.
8W/V% of 37% formalin and 7W/V% of 30% sulfuric acid as a hardening agent were added, and water was added to a predetermined liquid volume to uniformly knead. Put this kneaded adjustment liquid into a reaction mold made of PVC,
The mixture was reacted in warm water at 50°C for 20 hours, and after the reaction, it was deoxidized by showering for 3 days and dried. The dried material was cured at 150°C under a nitrogen stream, and the physical properties were measured. The results are shown in Table 1.

[Table] Example 2 Resol resin aqueous solution (PR961A manufactured by Sumitomo Dures)
Solid content: 64%) and polyvinyl alcohol (manufactured by Kuraray)
A granular phenol resin (manufactured by Kanebo Co., Ltd., trade name: Bell Pearl S, average particle diameter
30 μm) or amorphous silica powder (manufactured by Tokuyama Soda Co., Ltd.)
Add the product name Fine Seal T-32) in the amount shown in Table 2, resol resin, polyvinyl alcohol,
The total weight of the third substance is approximately 30W/V% of the total volume
(approximately 3 kg in the case of 10 preparations) to prepare a reaction stock solution. Using such a reaction stock solution, a reaction was carried out using the same types of pore forming agent, crosslinking agent and curing agent as in Example 1 in the same amounts, and under the same reaction operating conditions.
The physical properties of the sample thus obtained were measured in the same manner as in Example 1. The results are shown in Table 2.

[Table] *Nos. 2 to 4 used powdered phenolic resin, and Nos. 5 to 7 used amorphous silica.

Claims (1)

[Claims] 1 Resol type phenolic resin prepolymer 1
parts by weight, polyvinyl alcohol 0.02 to 0.2 parts by weight,
A pore-forming agent and an aldehyde are reacted in the presence of an acid catalyst to pre-cure the product, and then the pre-cured product is washed with water and dried, and then heated and cured to form a porous structure having continuous network pores. A method of manufacturing a material for a master model.