JPH1177233A - Release agent for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a releasing agent which facilitates the formation of an excellent releasing film, lessens the amt. of the gas to be generated which is the cause for blowholes and has a good releasing property by incorporating water which constitutes a dispersion medium, a water-soluble high polymer which at least partly dissolves in the water and an acrylic resin and silicone which constitute a dispersant. SOLUTION: This releasing agent is applied on the die surface segmenting the cavities of the dies and is in an aqueous form using the water as a dispersant. The agent is prepd. by dispersing the acrylic resin and the silicone in a suspended or emulsified state into the water. The water-soluble high polymer is at least partly dissolved in the water to denature the dispersant. Polyethylene glycol, polyoxyethylene, polyoxypropylene, etc., are used as the water-soluble high polymer and ester polymethacrylate, ester polyacrylate, etc., are used as the acrylic resin. Silicone oil, silicone resin, etc., are usable as the silicone. Inorg. matter may further be added s a seizure preventive agent to the releasing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold release agent for die casting which is applied to a die surface defining a cavity of a die such as a die cast.

[0002]

2. Description of the Related Art Many casting methods such as a die casting method and a low pressure casting method are known as mold casting methods.
Die casting uses a metal mold and injects a molten metal into the cavity of the mold to cool and solidify to produce a casting. When the molten metal comes into direct contact with the mold surface of the mold, the cooled and solidified casting is seized on the mold, making it difficult to release the casting from the mold. Therefore, a mold release agent is applied to the mold surface that defines the cavity to prevent the molten metal from burning on the mold surface.

Conventional mold release agents include lubricating oils composed of mineral oil, synthetic oil, animal and vegetable oils and the like, high-viscosity lubricating oils such as grease, natural wax, synthetic wax, silicone oil, and modified silicone. , Heat-resistant lubricants such as fluororesin powder, extreme pressure additives such as phosphorus compounds and sulfur compounds,
Those comprising a solid lubricant such as graphite, mica, talc, boron nitride, a surfactant, water and the like are generally known. Then, the compounding amounts of the heat-resistant lubricant and the solid lubricant are manipulated in accordance with the load on the release agent side due to the casting conditions of die casting, thereby obtaining a predetermined release agent.

Further, as a mold release agent for mold casting using a resin, one using a propylene polymer or a propylene copolymer (JP-A-6-240286), polyoxyethylene, or polyoxypropylene is used. Things (Japanese
No. 4-143725) is known. Die casting has these three features: hot water bath, burn-in galling, and burrow.
There are three major defects that account for 97% or more of casting defects. Regarding seizure, heat-resistant lubricants, solid lubricants,
Extreme pressure additives are not sufficient, but they are effective, lubricating oils that have an important function in extending to high-temperature molds and forming release films, and high-viscosity lubricating oils can cause hot water. It is known that gas generated from lubricating oil and high-viscosity lubricating oil due to heat of a high-temperature mold causes burrows. In addition, when the mold temperature is high, the adhesion efficiency of the release agent is poor, and there is a problem in forming a release film.

[0005]

DISCLOSURE OF THE INVENTION The present invention is superior to a conventional mold release agent for mold casting, is easy to form a release film, has a small amount of generated gas which causes burrows, and has a good release property. It is an object to provide a good mold release agent for mold casting.

[0006]

Means for Solving the Problems The present inventor has made intensive developments based on the above-mentioned problems. Although fats and oils have good lubricating properties, they have low molecular weight and are liable to induce evaporation, thermal decomposition, oxidation and the like. On the other hand, it was confirmed by a test that, when a resin having a high molecular weight was used as a main component of the mold casting release agent, evaporation, thermal decomposition, oxidation, and the like were hardly induced as compared with oils and fats. Further, an acrylic resin is further used as a resin, and a mixture of the acrylic resin and a water-soluble polymer such as polyethylene glycol or silicone can easily form a release film, generate less gas, and have good release properties. Was confirmed, and the present invention was completed.

That is, the release agent for mold casting of the present invention comprises:
The coating liquid is applied to a mold surface of a mold that defines a cavity to which a molten metal is supplied, and comprises water constituting a dispersion medium, a water-soluble polymer at least partially dissolved in the water, and a dispersant. And an acrylic resin and silicone. The acrylic resin and the water-soluble polymer form a good release film, and the silicone improves drainage.

[0008] By further adding a wax to the release agent of the present invention, the formation of a release film on a high-temperature mold is further enhanced. Further, by incorporating an inorganic substance, the seizure resistance is further increased.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A mold release agent for mold casting according to the present invention comprises water constituting a dispersion medium, a water-soluble polymer at least partially soluble in the water, an acrylic resin constituting a dispersant, and It is characterized by containing silicone. The release agent of the present invention uses water as a dispersant and is aqueous. The acrylic resin and silicone are dispersed or suspended in water in a state of being suspended or emulsified.

At least a part of the water-soluble polymer is dissolved in water to modify the dispersion medium. As the water-soluble polymer, polyethylene glycol, polyoxyethylene, polyoxypropylene and the like can be employed. In addition, alcohol can be blended according to the purpose. As acrylic resin, polymethacrylate, polyacrylate,
Specifically, polymethyl methacrylate, polybutyl acrylate, and the like can be used. A good result was obtained when the molecular weight of the acrylic resin was about 12,000 to 16,000.

As the silicone, silicone oil and silicone resin can be used. In particular, a silicone emulsion dispersed in water is easy to use. In addition to water, a water-soluble polymer, an acrylic resin, and silicone, which constitute the release agent of the present invention, a wax and an inorganic substance as an anti-seizure agent can be blended. As the wax, grease, natural wax, synthetic wax, or the like can be used, and as the inorganic substance, graphite, molybdenum disulfide, boron nitride, talc, mica, or the like can be used.

[0012] Incidentally, extreme pressure additives, hot water drainage improvers, defoamers, surfactants, heat stabilizers, which are usually compounded as a release agent,
Flame retardants and the like can be added as required. The surfactant has a function of increasing the dispersibility of the non-water-soluble acrylic resin, and higher alcohols, lauryl alcohol, alkyl ethers, sodium sulfate and the like can be used. The heat stabilizer suppresses the thermal change of the resin, and includes a tin compound (dioctyltin malate, etc.), a higher fatty acid salt (calcium stearate, zinc stearate, barium stearate, etc.), an epoxidized fatty acid (epoxidized Soybean oil), phosphites (such as triphenyl phosphite), and others (such as lead stabilizers, aminocrotonates, and zinc pyrrolidonecarboxylate).

The flame retardant imparts a self-extinguishing property to the resin, and includes a phosphoric acid ester (such as TCP tricresyl), a halogenated phosphoric acid ester (such as trispromochlorophosphate and trispropylphosphate), and a halogen compound (chlorinated paraffin and chlorine). Polyethylene, dechlorane brass, etc.), a reactive compound (hetic acid (chlorendic acid), etc.), a phosphorus-containing polyol (tetrapromobisphenol, etc.) and the like.

The release agent for mold casting of the present invention has a total solid content of 1
00% by weight (below, unless otherwise specified,
% By weight. ), The acrylic resin is 3 ~
40%, water-soluble polymer 1-20%, silicone 5-5
Preferably it is 30%. A resin such as an acrylic resin or a silicone resin preferably has a small average particle size. Generally, the maximum value of the average particle size of the resin is 50 μm, 500 μm.
And the minimum value is 0.01 μm or 1.0 μm.

At the time of coating, the release agent is diluted with a diluent such as water or alcohol (dilution ratio; for example, 50 to 300).
And apply it to the mold surface of the cavity of the mold by applying means such as spray spraying or brushing. Excess moisture is quickly evaporated by the heat of the mold, and a release film containing a resin component is formed. In addition, in the die casting mold of the molten aluminum, the temperature of the mold is 80 to 450 ° C. When the temperature of the mold is high, the acrylic resin and silicone constituting the release agent preferably have a higher molecular weight.

[0016]

EXAMPLES AND COMPARATIVE EXAMPLES Six types of mold release agents of samples 1 to 6 shown in Table 1 were prepared. In the composition shown in Table 1, silicone A is a silicone resin powder, silicone B is a silicone resin emulsion, acrylic resin A is an acrylic emulsion containing about 25% of an acrylic polymer having a molecular weight of 6,000 to 10,000, acrylic resin B
Is an acrylic emulsion containing about 33% of an acrylic polymer having a molecular weight of 12,000 to 16,000, an extreme pressure additive A is calcium stearate, an extreme pressure additive B is an emulsion of calcium stearate, and a water-soluble polymer, PEG. -A is polyethylene glycol having a medium molecular weight, PEG-B is polyethylene glycol having a high molecular weight, PEG-C is polyethylene glycol having a low molecular weight, wax is a paraffin wax emulsion, and titanium oxide is inorganic particles. Powder and the like were used, and a silicone antifoaming agent was used as an antifoaming agent. The numerical values in Table 1 are expressed in terms of weight% in terms of solid content after removing a solvent such as water.
(100% by weight as a whole).

Each of these release agents was blended according to the composition shown in Table 1 and prepared by sufficiently stirring.

[0018]

[Table 1] As a casting mold, a mold 1 whose main section is shown in FIG. 1 was used. The mold 1 is made of heat-resistant steel (JIS SKD61), is composed of a first split mold 12 and a second split mold 13, and has a volume 250c into which a molten metal is poured into a mating surface.
m ³ cavities 10 are formed. The draft of the cavity 10 was 2 degrees.

The first split mold 12 has an injection plunger 3
Is equipped. The injection plunger device 3 is reciprocally fitted in the sleeve 31 formed of heat-resistant steel or the like having a sleeve chamber 30 communicating with the cavity 10 of the mold 1 via the runner biscuit 11. And a plunger tip 32. The sleeve 31 has a hot water supply drop port 34. The plunger tip 32 is operated pneumatically or hydraulically.

The mold 1 is fixed to a mold clamping device 4 of a die casting device. A load cell 45 is arranged between the pushing plate 41 and the pushing pin 42 which are interlocked with the mold clamping device 4, so that the pushing force acting on the pushing pin 42 can be measured. The casting test was performed by a die casting apparatus having the mold 1, the casting plunger device 3, and the mold clamping device 4 for each release agent of each sample. The mold temperature of the mold 1 was set at three levels of 150 ° C., 350 ° C., and 400 ° C. by controlling the amount of cooling water sent to a cooling coil (not shown) embedded in the mold 1. An aluminum alloy having a JIS ADC12 composition was used as the molten metal, and the temperature of the molten metal was 670 ° C. The mold clamping pressure was 350 tons and the injection speed was 0.8 m / s.

The release agent is applied by a gravity method having a diameter of 1.3 mm,
Using a flat-blow air gun, set the solids concentration of the release agent to 1
Using about 1.3 g per 000 cm ^{3, it is} sprayed with an air pressure of 4 kg / cm ² on the mold surface of the mold 1 forming the cavity 10 so that the solid content becomes about 0.6 mg per 1 cm ² of the mold surface. Was. Thereafter, each of the shots was performed ten times, and the casts were checked for mold release, presence of cavities, and the like.

In the case of the release agent of Sample 1, a casting cast by several shots was welded to a mold and stuck, and the performance as a release agent was low. Sample 2, Sample 3, Sample 4, Sample 5
In addition, each of the release agents of Sample 6 was stuck and did not show any inconvenience such as a cavity, and could be used as a release agent. However, in the case of Sample 2, when there is uneven application of the release agent,
In some cases, it was close to sticking where mold release was difficult. Also,
The release agent of Sample 3 was also improved compared to the release agent of Sample 2, but had a problem in mold release.

The release agents of Sample 4, Sample 5 and Sample 6 exhibited high performance with no casting problems such as mold release and cavities. Therefore, acrylic resin B is better than acrylic resin A
It turns out that it is more preferable. FIG. 2 is a graph showing the relationship between the number of shots and the value measured by the load cell 45 for the extrusion load acting on the extrusion pin 42 when three types of release agents, Sample 3, Sample 4 and Sample 6, are used. . For reference, two types of release agents commercially available as release agents for mold casting, commercially available products A and B are shown in FIG. 2 together with the extrusion loads when tested under exactly the same conditions. .

The composition of the commercial product A is modified silicone oil: 4.0%, fats and oils: 15.0%, synthetic oil;
5%, surfactant; 7.5%, rust / preservative; 1.0
%, Water; 65.0%. The composition of the commercial product B is as follows: oils and fats: 15.0%, mineral oil: 5.5%, synthetic oil;
7.5%, surfactant; 5.5%, rust / preservative;
0%, water; 65.5%.

FIG. 2 shows that the release agent of Sample 3 of the present invention has an extrusion load almost the same as that of the commercial product A. It can be seen that the two types of release agents of Samples 4 and 6 of the present invention have lower extrusion loads than the commercial products A and B, and have excellent mold release properties. In order to investigate the adhesiveness of the release agent, using a steel plate of 80 mm in length and width and 1 mm in thickness as a model instead of the mold, tilt the coating surface on a hot plate at an angle of 80 ° to the horizontal plane, Under the same conditions as those applied to the mold surface of the mold perpendicularly to the iron plate, the two types of release agents of Samples 3 and 4 of the present invention and the two types of commercially available products, commercially available products A and The adhesion amount of the commercial product B was measured. The application amount is obtained by applying 10 g of a release agent at a predetermined dilution ratio in about 13 seconds, and after applying the solid content adhering to the iron plate as an increase in weight. It should be noted that the dilution ratio was 30 times, 50 times and 100 times.
The solids content in 10 g of the double release agent was about 0.043 g, 0.026 g and 0.0
13 g, and the commercial product A is 0.110 g, 0.065 g
g, 0.033 g, commercial product B: 0.101 g, 0.06 g
1 g and 0.030 g.

FIG. 3 shows the results when the temperature of the iron plate is 150 ° C.
FIG. 4 shows the results when the temperature of the iron plate is 350 ° C.
The number in parentheses in the figure indicates 10 g of the diluted release agent.
The ratio of the solids adhered to the solids in the medium is represented by% by weight. 3 and 4, it can be seen that the release agent of the present invention has extremely high adhesiveness as compared with a commercially available release agent.
In particular, as shown in FIG. 4, the amount of adhesion at 350 ° C. is lower than the amount of adhesion at 150 ° C. in general, but the release agent of the present invention has a small decrease in the amount of adhesion and has a small mold temperature dependence of the adhesion. ,
It can be seen that the amount of adhesion is stable.

Next, the amount of generated gas which causes a casting cavity was compared by the following method. As the release agent, two types of release agents of Samples 3 and 4 of the present invention and two types of commercially available products A and B were used.
A total of four types of release agents were tested. In the test, an appropriate amount of each release agent was heated at 130 ° C. for 30 minutes to dry off the solvent such as water, and 0.5 g of the remaining solid content was filled in a copper pipe and loosely plugged with asbestos. The reactor was driven into a closed furnace in a nitrogen atmosphere at 700 ° C., and the pressure inside the furnace, which was increased by the generated gas, was measured. The results are shown in FIG.

FIG. 5 shows that the two types of release agents of the present invention generate a small amount of gas. From this, it can be understood that the mold release agent of the present invention generates few cavities. From these results, as the mold temperature increases, it becomes difficult to adhere to the mold as seen in the conventional mold release agent. It can be seen that the problem that the work environment is deteriorated due to the accumulation in the periphery of the work and that the work environment is deteriorated, and that the release agent of the present invention can solve problems such as the generation of stains that cannot be washed out due to graphite and the like contained in the release agent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a mold used for evaluating a release agent and a main part of a mold clamping device.

FIG. 2 is a diagram showing a relationship between an extrusion pin load and a shot number for each release agent.

FIG. 3 is a diagram showing the relationship between the adhesion amount of solids of a release agent and the dilution ratio at an iron plate temperature of 150 ° C. for each release agent.

FIG. 4 is a graph showing the relationship between the adhesion amount of solids of a release agent and the dilution ratio at an iron plate temperature of 350 ° C. for each release agent.

FIG. 5 is a graph showing the amount of gas generated for each release agent.

[Explanation of symbols]

1 is a mold, 10 is a cavity, 3 is a casting plunger device, 30 is a sleeve chamber, 31 is a sleeve, 32 is a plunger tip, 4 is a mold clamping device, 42 is an extrusion pin,
Reference numeral 5 denotes a load cell.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Koriichi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shoichi Tsuchiya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yuji Sengoku 57-1, Hashime-cho, Okazaki-shi, Aichi Pref. 36-3 Higashiishine, Ichiriyama-cho, Kariya-shi Sanwa Yuka Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A mold casting release agent applied to a mold surface of a mold defining a cavity to which a molten metal is supplied, comprising: water as a dispersion medium; and at least partially dissolved in the water. A mold-release agent comprising: a water-soluble polymer; and a dispersant, acrylic resin and silicone. 2. The mold release agent according to claim 1, further comprising a wax. 3. The mold release agent according to claim 1, further comprising an inorganic substance as an anti-seizure agent.