JPH01224137A - Manufacture of resin pattern for casting - Google Patents

Abstract

PURPOSE:To obtain a resin pattern having excellent microwave resistance by coating polyurethane resin on surface of a master model to form surface layer, setting a flask, packing material and separating master model after hardening the packing material. CONSTITUTION:After applying parting agent 2 on the surface of master model 1 of wooden pattern, resin pattern, gypsum pattern, metallic mold, etc., the polybutadiene series polyurethane resin is gel-coated as the pattern surface material at the prescribed thickness to form the surface layer 3. The flask 4 is set and backup material 5 is packed under still tacking condition of the surface layer 3. As the backup material, the material uniformly mixing 50 parts of sand, 50 parts of foaming alumina and 15 parts of polyurethane resin, is used. This material is temporarily hardened at room temp. and after separating the master model, it is secondarily hardened by heating at the prescribed temp. for the prescribed time to make the pattern. As the surface layer 3 has excellent microwave resistance, heat resistance, wear resistance and crack resistant strength, the pattern having excellent durability at the time of molding without breakage of the pattern, can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a mold in which a model is filled with molding sand, the mold is inserted into a microwave heating furnace, and the molding sand is hardened by irradiation with microwaves. The present invention relates to a method of manufacturing a resin model for casting with excellent microwave resistance used in the manufacturing method.

[Conventional technology]

A non-polar resin is applied to the surface of the master model as a material that allows microwaves to pass through and does not generate internal heat to form a resin layer. This resin layer is released from the master model and heated to harden and form the model. A model manufacturing method is known.

As the aforementioned non-polar resins, thermoplastic resins such as polyethylene and fluoroplastics, and thermosetting resins such as silicone are known, but polyethylene and fluorocarbon resins have low heat resistance and are easily deformed by heat. However, silicon has the drawbacks of low strength, wear resistance, and durability.

Therefore, a reinforcing material made of a mixture of non-polar epoxy resin with good microwave transparency and inorganic aggregate such as silica and alumina particles was applied to the surface of the master model, and silicone rubber was applied on top of the reinforcing material, which was then heated and cured after being released from the mold. The method of manufacturing the model is such that the front side is made of silicone rubber and the back side is reinforced with a reinforcing material.

[Problem to be solved by the invention]

When a model manufactured using such a model manufacturing method was repeatedly used to create a mold, the silicone rubber used as the surface layer of the model was damaged during the modeling process due to its low tear strength, and the caking material used as a reinforcing material was damaged. The non-polar epoxy resin used as a mold is also affected by the heat of the mold during microwave heating and curing, causing it to become brittle and breakage, so when mass producing molds using microwave heating, it is necessary to repeat molds with stable quality. Cannot be modeled.

In other words, models manufactured by conventional model manufacturing methods have poor durability and break when used repeatedly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a resin model for casting that can easily produce a model with excellent microwave resistance, abrasion resistance, heat resistance, and tear strength (and durability).

[Means to solve the problem]

In this model manufacturing method, a polyurethane resin is coated on the surface of a master model to a predetermined thickness as a surface layer, a mold is set, a backing material is filled, and the mold is released from the master model after curing. As a result, the model has excellent microwave resistance, as well as stronger heat resistance, abrasion resistance, and tear strength, which improves durability, thereby stabilizing the durability during modeling and the quality of the mold. be able to.

In the present invention, as the polyol used for the surface layer and the polyurethane resin of the binder, those commonly used for polyurethane are used.

Examples include polyether polyol, polyester polyol, active hydrogen group-containing polybutadiene, castor oil, and polycarbonate diol. Polyether polyols include polyhydric alcohols, polyhydric phenols,
Examples include compounds having a structure in which alkylene oxide is added to a polyfunctional compound containing an active hydrogen atom, such as polycarboxylic acid. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1°4-butanediol,
1. Dihydric alcohols such as 6-hexanediol, diethylene glycol, neopentyl glycol, and trivalent or higher polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose; polyhydric phenols include pyrogallol, In addition to polyhydric phenols such as hydroquinone, bisphenols such as bisphenol A; and polycarboxylic acids such as aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, maleic acid, and dimer acid, phthalic acid, terephthalic acid, and trimethic acid. Aromatic polycarboxylic acids such as Two or more kinds of the above-mentioned active hydrogen atom-containing compounds can also be used.

Examples of the alkylene oxide to be added to the active hydrogen atom-containing polyfunctional compound include ethylene oxide, propylene oxide, butylene oxide (tetrahydrofuran), and the like. The alkylene oxides may be used alone or in combination of two or more, and in the latter case, block addition or random addition may be used. Preferred among these alkylene oxides are tetrahydrofuran, propylene oxide and ethylene oxide.

Examples of polyester polyols include condensed polyester polyols and lactones (epsilon-caprolactone, etc.) obtained by reacting low-molecular polyols (the above-mentioned dihydric alcohols, trimethylolpropane, glycerin, etc.) with dicarboxylic acids (the above-mentioned polycarboxylic acids, etc.). Examples include polyester polyols obtained by ring-opening polymerization.

The active hydrogen group-containing polybutadiene is one obtained by polymerizing butadiene and having an active hydrogen group such as a hydroxyl group, a carboxyl group, or an amine group at the end and having about 80% of 1.4 bonds;
A material containing about 90% of 1,2 bonds can be used. Among these, preferred are polyester polyol, active hydrogen group-containing polybutadiene, and castor oil. Among these, active hydrogen group-containing polybutadiene containing two or more hydroxyl groups or carboxyl groups, and castor oil are particularly preferred. These may be used in combination if necessary.

The OR value is not particularly limited, but is usually 30 to 500, preferably 40 to 450.

In the present invention, as the polyisocyanate used for the surface layer and the polyurethane resin of the binder, those commonly used for polyurethane are used. For example, carbon (NC
Aromatic polyisocyanates [2° 4- and/or 2.6-) lylene diisocyanates] (TDI), crude TDI, 2.4'- and/or 4 , 4'-diphenylmethane diisocyanate (MDI), crude MDI [crude diaminodiphenylmethane (a condensation product of formaldehyde and an aromatic amine (aniline) or a mixture thereof) diamino diphenylmethane and a small amount (e.g. 5 to 20% by weight) of trifunctional phosgenated product of the above polyamine (mixture with polyamine): polyaryl polyisocyanate (PAPI) 1 etc.]: carbon number 2-18
Aliphatic polyisocyanate [hexamethylene diisocyanate, lysine diisocyanate, etc.]: Oxygen number 4
~15 ring type polyisocyanates (isophorone diisocyanate, dicyclohexyl methylene diisocyanate, etc.): Aroaliphatic polyisocyanates having 8 to 15 carbon atoms [xylylene diisocyanate, etc.]: and modified products of these polyisocyanates (urethane group, carbodiimide, etc.) (allophanate group, urea group, biuret group, uretdione group, uretonimine group, isocyanurate group, oxazolidone group-containing modified products, etc.); and polyisocyanates other than the above described in Japanese Patent Application No. 199180/1983, and these 2 Examples include mixtures of more than one species.Among these, preferred are 2.4.
- and 2.6-TDI and mixtures of these isomers, 2.4'- and 4.4'-MDI and mixtures of these isomers, and urethane groups derived from these polyisocyanates, carbodiimides N
C0% is usually 15 to 45%, preferably 20 to 35%.

As the thixotropic agent used in the present invention, surface-treated inorganic fillers and synthetic waxes commonly used for urethane are used. Examples of these include colloidal hydrophobic silica, surface-treated calcidic precipitated calcium carbonate, and hydrogenated castor oil. Preferred are surface-treated calcite-type precipitated calcium carbonate and hydrogenated castor oil.

The foam stabilizer used in the present invention is usually one for soft urethane foam. For example, L-540 (
Nippon Unicar), 5H-190, 5RX-294A
(manufactured by Toray Silicone ■).

Known catalysts can be used in the present invention. Specifically, metal catalysts such as tin-based catalysts [trimethyltin dilaurate, dimethyltin dilaurate, stannath octoate, etc.], lead-based catalysts [lead oleate, lead 2-ethylhexanoate, lead naphthenate, etc.], and other Metal catalyst [
Naphthenic acid metal salts such as cobalt naphthenic acid];
Amine catalysts such as triethylenediamine, tetramethylhexylenediamine, diazabicycloalkenes [
DBU (11.8-diazarbicyclo [manufactured by San Ablo
5,4,01 undecene-7), etc.] ; Examples of trimerization lines include metal salts of carboxylic acids, such as sodium acetate, lead octylate, zinc octylate, cobalt naphthenate, etc.; alkali and alkaline earth metals alkoxides and phenoxides, such as sodium methoxide, sodium phenoxide, secondary tertiary amines, such as triethylamine, triethylenediamine, N-methylmorpholine, dimethylaminomethylphenol, pyridine, etc.; quaternary ammonium bases, such as tetraethylammonium hydroxy; ;Imidazoles such as imidazole, 2-ethyl-4-methylimidazole, etc. can be mentioned. Preferred among these are trimerization catalysts. Two or more of these may be used in combination if necessary.

As additives that may be used as necessary, fillers (wood flour, asbestos, mica, bulb powder, etc.) and colorants can be added to improve heat resistance and shrinkage rate.

NCO of the polyurethane resin of the surface layer used in the present invention
The index is usually 100 or more, preferably 130-500. Outside this range, adequate wear resistance cannot be obtained.

N of the polyurethane resin of the binder used in the present invention
The CO index is usually 100 or more, preferably 300 or more. Outside this range, sufficient heat resistance cannot be obtained.

Curing in the present invention is performed by heating at 100°C to 200°C. Preferably it is 110°C to 180°C.

Heat resistance is low outside this range.

The number of parts of the thixotropic agent used is usually 5 parts to 200 parts, preferably 10 parts to 150 parts, per 100 parts of the polyol. Outside this range, there will be no thixotropy or the workability will be poor. The amount of foam stabilizer used is 0 to 5 parts, preferably 0 to 3 parts, per 100 parts of polyol.

The amount of catalyst used is 0.1 to 5 parts, preferably 0.3 to 3 parts, based on 100 parts of polyol.

Outside this range, an appropriate curing time cannot be obtained.

The amount of additives used as necessary is 10% of the polyol.
The amount is usually 0 to 10 parts, preferably 0 to 5 parts.

The coating of the present invention is preferably brushed or sprayed.

〔Example〕

A first example will be described below.

Specific Example 1 As shown in FIG. 1(a), after applying a mold release agent 2, such as Daifree MS-743, to the surface of a master model 1 such as a wooden mold, resin mold, plaster mold, or metal mold, a first As shown in Figure (b), the model surface material was a polybutadiene-based polyurethane resin (a mixture of 100 parts of the main agent Polycure GC-100 and 30 parts of the curing agent Polycure IS-703).

The surface layer 3 is formed by gel coating an NCO index of 105) to a thickness of about 21.

As shown in FIG. 1(C), it is set in a mold 4 and filled with a back-up material 5 while the gel-coated polyurethane resin surface layer 3 is still tacky. Backup material 5
50 parts of sand, 50 parts of foamed alumina, polyurethane resin (3 parts of main agent Polycure RF-100, 12 parts of hardening agent Polycure IS-703. NCO index is 86
8) 15 parts were evenly mixed.

This material was primarily cured at room temperature, released from the mold as shown in FIG. 1(d), and then heated at 120° C. for 1 hour to be secondarily cured to form a model.

Specific Example 2 The model surface material in Specific Example 1 was a silicone-based polyurethane resin (a mixture of 100 parts of the main ingredient Polycure C200 and 29 parts of the curing agent Polycure I 5703), and the other conditions were the same as in Specific Example 1. was manufactured.

Specific Example 3 The model surface material in Specific Example 1 was a polybutadiene-based polyurethane resin (a mixture of 100 parts of the main agent Polycure SP and 41 parts of the curing agent Polycure 13703).
was sprayed to a thickness of about 2111@ using a spray device (APV-5000 manufactured by Asahi Okuma Sangyo ■). A model was manufactured in the same manner as in Example 1 in other respects.

Comparative example: Using silicone rubber (RTV) as the model surface material,
2 w+ of master model and back up material in advance
It was manufactured by casting during s.

Backup material: 50 parts sand, 50 parts foamed alumina
A uniform mixture of 15 parts and 15 parts of non-polar epoxy was filled into a mold and cured at 150°C for 4 hours.

The properties of the models manufactured by each manufacturing method were measured and were as shown in the table below.

*1 Microwave resistance is microwave output 0.5kvlo
The temperature difference of the test piece before and after the measurement was measured by irradiating the test piece for several minutes.

*2 Microwave resistance is greater than the difference in surface temperature of a φ50 x 50H test piece when irradiated with a microwave output of 8 kV for 5 minutes. Therefore, the microwave resistance, wear resistance, and It can be seen that the heat resistance and tear strength are superior to the models manufactured in comparative examples.

A second embodiment will be described below.

Specific Example 1 As shown in FIG. 2(a), after applying a mold release agent 2, such as Daifree MS-743, to the surface of a master model 1 such as a wooden mold, resin mold, plaster mold, or metal mold, As shown in Figure 2 (b), the surface layer was made of a polybutadiene polyurethane resin (100 parts of the main ingredient Polycure CC-100 and a curing agent lS-
A mixture of 30 parts of 703. NCO index is 105)
This is made into a gel and coated with a brush 6 to a thickness of about 2 am to form the surface layer 3.

As shown in FIG. 2(C), the mold is set in a mold 4, and the back-up material 5 is filled with the surface coated polyurethane resin surface layer 3 in a tacky state. Backup material 5
The ingredients include 50 parts of silica sand, 50 parts of foamed alumina, 6.8 parts of polyether polyol (OH value 405), 0.034 parts of dibutyltin dilaurate, and modified MDI (NC0%26).
) 8.2 parts (NCO index: 103) were uniformly mixed.

This material was primarily cured at room temperature, released from the mold as shown in FIG. 2(d), and then heated at 120° C. for 1 hour for secondary curing to form a model.

Concrete Example 2 The model surface material in Concrete Example 1 was a silicone-based polyurethane resin (a mixture of 100 parts of the main ingredient Polycure Cl2O and 72 parts of the curing agent Polycure I 5703. The NCO index was 105), and the other parts were as in Concrete Example 1. A model was made in the same way.

Comparative Example The model surface material of Example 1 was coated with an epoxy gel coat agent (100 parts of Nidek 420 as the main agent, 1 part of hardening agent-modified polyamine).
A model was produced in the same manner as in Example 1 except for the following.

The performance of the model thus manufactured and the sagging properties when the model surface material was vertically brushed were measured and the results are shown in the table below.

In addition, the wear resistance was determined by measuring taper wear of a worn wheel H-22 at a load of 1 kg and a number of rotations of 1000 times.

From the above, the model according to Specific Example 1.2 has a small amount of wear, which is 1/3 to 1/6 of the model according to the comparative example, and has excellent wear resistance. The work is easy because there is no need to lean, and the film thickness can be made uniform.

That is, by brushing the thixotropic polyurethane resin, it can be easily brushed without sagging even when applied to a vertical surface, and the thickness of the surface layer 3 can be made uniform.

A third embodiment will be described below.

In this example, the surface of the master model is coated with a one-component polyurethane resin, and then the polyurethane resin is coated by a spray method or a gel coat method to create a surface layer. In this way, a model with a bubble-free surface can be obtained.

In other words, with polyurethane resin coated by spraying or gel coating, the surface of the master model tends to bubble or foam due to moisture in the air, and as a result, the surface of the model tends to be in poor condition with bubbles.
If you coat the surface of the master model in advance with a one-component polyurethane resin to create a bubble-free film, the surface layer of the polyurethane resin coated with the spray method or gel coat method will adhere to the coated film, and the master model will be coated with a one-component polyurethane resin. When the mold is released from the model, a film without bubbles becomes the surface of the model, so the surface condition of the model becomes good without bubbles.

Specific Example 1 As shown in Figure 3(a), Daifree MS-743 was applied as a mold release agent 2 to the surface of the Mass Master Model 1 with a brush 7, and a one-component liquid was applied as a surface coating agent to the surface. A polyurethane resin (Polycure C-100) is applied and dried to form a film 8. See Figure 3 (a b).

As shown in FIG. 3(C), as a polyurethane resin, 28 parts of polyether polyol (OH value 33), 15 parts of ethylene glycol, 0.5 part of 5AG47 (antifoaming agent), and 1.0 part of Dabco33LV. , 100 parts of a stock solution uniformly mixed with 0.05 parts of DTD (dibutyltin dilaurate) and 75 parts of modified MDI (NC0%-26) (N
CO index is 108) using an airless two-component spray device 9
(APW-5000 manufactured by Asahi Okuma Sangyo ■) was spray coated onto the film 8 of the master model 1 to a thickness of about 2 mws and cured to form the surface layer 3 of polyurethane resin.

The two-component spray device 9 includes first and second containers 10 and 11.
A predetermined amount of the stock solution, modified MDI, is sent to a static mixer 13 by a metering pump 12, mixed, and injected from a nozzle 14. 15 is a heating device.

The formwork 4 is set as shown in FIG. 3(d), and the surface layer 3 is
In a state where there is tack, the back-up material 5 is filled and hardened. As the back-up material 5, 50 parts of silica sand, 50 parts of foamed alumina, and polyether polyol (OH value 40
5) 6.8 parts DTDo, 0034 parts and modified MDI (N
A mixture of 8.2 parts of C0%-26) (NCO index: 103) was added and mixed.

As shown in FIG. 3(e), the master model 1 is released from the mold to form a model.

Specific Example 2 In place of the polyurethane resin of Specific Example 1, 100 parts of polyether polyol (OR value 405), 0.5 part of 5AG-47 (antifoaming agent), Dabc.

Polyurethane resin (
A model was produced in the same manner as in Example 1 except that 106 parts of the stock solution and 120 parts of modified MDI (NCO% 26) (NCO index: 103) were coated by a spray method.

Comparative Example 1 A model was manufactured in the same manner as in Example 1, except that the surface coating agent in Example 1 was an epoxy gel coat agent (manufactured by Nippon Debcon ■, a mixture of 100 parts of NIDEK420 and 11 parts of hardener-modified polyamine). .

Comparative Example 2 A model was manufactured in the same manner as in Example 1 except that no surface coating agent was used and 5AG-47 (antifoaming agent) in the polyurethane resin was not used.

We measured the surface condition, wear resistance, and hardness of each model.
It became as shown in the table below.

The wear resistance was measured by a taper wear test using a worn wheel H-22 at a load of 1 kg and a number of rotations of 1000 times.

The embodiment of FIG. 4 will be described below.

In this example, a surface layer is formed by gel coating a polyurethane resin consisting of polyol, polyisocyanate, a thixotropic agent, a foam stabilizer, and a catalyst on the surface of a master model, and the model is manufactured in the same manner as in the second example. It is something.

Concrete Example 1 As shown in FIG. 2(a), after applying a mold release agent 2, such as Guifree MS-743, to the surface of a master model 1 such as a wooden mold, resin mold, plaster mold, metal mold, etc., as shown in FIG. As shown in (b), 100 parts of purified castor oil (08 value 160) was used as a polyol for the surface layer polyurethane resin, 100 parts of polyisocyanate-modified MDI (NC0%26) (NCO index was 217), and the surface was treated as a thixotropic agent. 70 parts of calcite-type precipitated calcium carbonate (Gelton 50 (manufactured by Shiraishi Calcium ■), as a foam stabilizer (SH-190 (
)-Resilicone ■) and 0.05 part of Polycat 42 (SanAvro ■) as a trimerization catalyst were mixed and gel-coated to a thickness of 2 times with a mold on a mold at a mold temperature of 60°C. After 1 hour and 30 minutes, a mixture of 3 parts of Polycure RF-100J and 12 parts of Polycure IS-703J, a modified MDI (NCO index 868), was applied to the surface layer 3, as shown in Figure 2 (c). , the formwork 4 is set and the backup agent 5 is filled.

As backup agent 5, 75 parts of sand and 25 parts of foamed alumina were used.
A mixture of 3 parts of Polycure RF-100J and 12 parts of Polycure 1S-703J (NCO index 868) was used.

This material was secondarily cured at 150° C. for 2 hours to form a model.

Specific Example 2 A model was produced in the same manner as in Specific Example 1, except that the number of polyisocyanate used in the polyurethane resin used in the surface layer was 150 parts (NCO index 326).

Specific Example 3 Specific Example 1 except that 50 parts of surface-treated hydrogenated castor oil (manufactured by Suishi Kasei Co., Ltd.) was used instead of the surface-treated calcite-type precipitated calcium carbonate used in the surface layer in Specific Example 1. A model was made in the same manner. However, Disbaron 4
110 was dissolved in Akaji refined castor oil.

The performance of the above-mentioned specific examples as surface materials and back-up materials was measured, and the results were as shown in the table below.The measurement method was as described above.

A liquid coating mold was attached to the model manufactured according to the above specific example, and molding sand was filled in the mold, and the molding sand was hardened by inserting the mold into a microwave heating furnace and irradiating it with microwaves. The results are shown in the table below.

Table [Effects of the invention] Surface layer 3 has excellent microwave resistance, heat resistance, abrasion resistance,
Since the tear strength is increased, the model will not be damaged even if it is used repeatedly to make a mold, and it will have excellent durability during molding, and the quality of the mold will be stabilized. You can easily produce a model.

[Brief explanation of the drawing]

Figure 1 (a), (b), (c), (
d), Figure 2 (a), (b), (c), (d), 3rd
Figures (a), (b), (c), (d), and (e) are explanatory diagrams showing the first, second, and third embodiments of the present invention in the order of steps. 1 is the master model, 3 is the surface layer. Applicant Komatsu Co., Ltd. Manufacturer Sanyo Chemical Industries Co., Ltd. Agent Patent attorney Masaaki Yonehara Patent attorney
Tadashi Hamamoto Figure 1 (b) ``λ Oho No. 3

Claims (1)

[Claims] 1. The surface of the master model is coated with polyurethane resin to a predetermined thickness as a surface layer, a mold is set, a backing material is filled, and after curing, the mold is released from the master model. A method for manufacturing a resin model for casting, characterized by: 2. The method for manufacturing a resin model for casting according to claim 1, wherein the polyurethane resin of the surface layer is a resin made from a polyol, polyisocyanate, a thixotropic agent, a foam stabilizer, a catalyst, and other additives if necessary. . 3. The method for manufacturing a resin model for casting according to claim 1 or 2, wherein the polyurethane resin of the surface layer has an NCO index of 100 or more. 4. The method for producing a resin model for casting according to claim 2 or 3, wherein the thixotropic agent is a surface-treated inorganic filler or synthetic wax. 5. The method for manufacturing a resin model for casting according to any one of claims 1 to 4, wherein the backing material uses a binder made of polyurethane resin. 6. The NCO index of the binder polyurethane resin is 10.
6. The method for manufacturing a resin model for casting according to claim 5, wherein the amount is 0 or more. 7. The method for manufacturing a resin model for casting according to any one of claims 1 to 6, wherein the curing is performed by heating at 100°C to 200°C.