KR101643252B1 - Method for Manufacturing Ceramic Razor Blade by Injection Molding - Google Patents

Abstract

The present invention relates to a method for manufacturing a ceramic razor blade using an injection molding method while having economic efficiency. The ceramic razor blade manufactured by the method of the present invention has an excellent cutting force, reduced weight, and hygienic since the ceramic razor blade is made of ceramic of fine particles and is easily manufactured using an injection molding method to reduce manufacturing costs as compared with the existing steel razor blade or the existing ceramic razor blade made by using a press molding method. Moreover, a core unit of the ceramic razor blade has high hardness and a surface of the ceramic razor blade has high toughness. Therefore, the present invention can restrain surface damage while maintaining overall high strength of the razor blade and removes structural non-uniformity inside the razor blade to prevent bending of the razor blade.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a ceramic razor blade by injection molding,

The present invention relates to a method for manufacturing a ceramic blade economically using an injection molding method.

Generally, a razor blade is used to cut the hair of the human body in contact with the human skin, and most of these razor blades are made of metal.

However, the metal razor is difficult to maintain affinity with the skin, and it is highly likely to be contaminated and deteriorated due to oxidation caused by frequent contact with moisture and air during use. In case of severe rust, The problem to be replaced and the metallic razor blade may breed germs and damage the skin. The germs propagated on the razor blade may penetrate into the skin during shaving through the damaged skin.

As a method for improving the above problem, a method of thinning an oil-based and inorganic coating material on a metal razor blade has been proposed. In this method, a base material such as stainless steel is usually used. In order to increase the hardness of a razor blade, And then depositing various coating materials on the edge.

In order to increase the strength and durability of the razor blade, the coating material may be a thin film of a carbide, nitride, oxide, or the like, which is a general hard thin film material, such as a metal or ceramic, and may reduce frictional force with the skin and improve shaving performance An organic material such as PTFE (polytetrafluoroethylene) may be deposited.

However, the hard thin film material and the organic material such as PTFE have poor adhesion to the base material such as stainless steel, and the organic material has a problem of drastically reducing the cutting force against the hair.

Accordingly, instead of thinning a coating material on a metal base material, a ceramic razor blade in which a whole razor blade is molded with ceramic has been proposed. Such a ceramic razor blade has advantages in terms of cutting ability, rust resistance and smell, I have.

A method of manufacturing a razor blade using ceramics includes a method of forming a razor blade by cutting, grinding, or cutting a single crystal sapphire or a method of forming a razor blade by etching a single crystal. The ceramic razor using such a single crystal has high brittleness Even if a little shock is applied, it is easy to brittle, and the price is higher than a general stainless steel razor blade, which is uneconomical.

In addition, there is a method of processing using a polycrystalline ceramic sintered body. In the process of manufacturing the ceramic sintered body, the ceramic powder is uniaxially pressed, formed into a sintered body by isostatic pressing, and sintered by sintering.

It is difficult to fabricate a precise sintered body due to warpage and local sintering shrinkage difference during sintering due to unevenness of forming pressure of the molded body during uniaxial pressing, which is a general molding method of ceramic powder. Thereby obtaining a polycrystalline ceramic sintered body.

Thereafter, the sintered body is formed into a block for a blade by cutting, grinding, cutting, etc., and the blade for a blade is further cut, polished and cut to form a blade. Which accounts for 80% of the cost, and the production cost of the ceramic blade is much higher than that of the metal blade, which makes it difficult to popularize the ceramic blade.

Accordingly, a method of forming a ceramic through injection molding has been proposed. The injection molding method can minimize the unevenness in molding that occurs during molding, and can produce a ceramic sintered body having dimensions similar to those of a ceramic blade block. There is an advantage that the cost can be reduced.

In this way, Korean Patent Laid-Open Publication No. 2011-0088922 discloses a method of manufacturing a ceramic multi-blade blade by an injection molding method, comprising the steps of: preparing a zirconia ceramic sintered body; injecting and molding the zirconia ceramic sintered body; Shaping the blade-shaped body, performing planarization by shaving the upper and lower surfaces of the blade-shaped body; And lapping the razor blade of the multiple blade shaping body to form a blade.

At this time, the step of preparing the zirconia ceramic sintered body includes a first step of mixing the zirconia ceramic raw material, the binder and the plasticizer to form a mixed raw material, and spraying the mixed raw material into the air flow formed with the heated air, A second step; A third step of pressing the mixed raw material having the second step to produce a first shaped body; A fourth step of subjecting the first formed article to cold isostatic pressing in which the same pressure is applied to the liquid at a low temperature using a pressure medium; A fifth step of sintering the first formed body subjected to the cold isostatic pressing; And a sixth step of performing hot isostatic pressing in which the first formed body subjected to the sintering operation is pressurized by the expansion pressure of the gas. Since the molding is performed through injection molding, the manufacturing cost can be lowered compared with the conventional method.

However, the ceramic multi-blade which is manufactured by the above method is manufactured by forming a ceramic sintered body through pressure molding, cold isostatic pressing, sintering, hot isostatic pressing, and then molding the ceramic sintered body by injection molding, The sintered body is not satisfactory in fluidity and injection molding is difficult, and the binder in the raw material is decomposed into carbon and contained in the sintered body. Carbon can improve the strength of the sintered body, but the sintered body is increased in brittleness, There is a problem causing defects.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a ceramic razor blade capable of reducing the manufacturing cost of a ceramic razor blade by using an injection molding method and having excellent mechanical properties and preventing product defects such as surface breakage, And a method for producing the same.

In order to solve the above-mentioned problems, the present invention provides a method of manufacturing a ceramic material, comprising heating and mixing a mixture of 70 to 80% by weight of a ceramic and 20 to 30% by weight of a polymer at 150 to 180 캜; Preparing a ceramic blade shaped body by injection molding the heated mixed mixture; A degassing step of firstly heating the molded body at 100 to 150 ° C for 20 to 30 hours, then secondarily heating at 150 to 250 ° C for 20 to 30 hours, and then thirdly heating at 450 to 550 ° C for 20 to 30 hours; Subjecting the degreased molded body to a heat treatment at 1500 to 1600 ° C for 1 to 2 hours; And lapping the heat-treated molded body to form a blade. The present invention provides a method of manufacturing a ceramic blade by injection molding.

Preferably, the ceramic is a square yttrium oxide zirconia partially stabilized with yttrium, and the polymer is at least one selected from the group consisting of paraffin wax, low density polyethylene, ethylene vinyl acetate and stearic acid.

The injection molding is preferably performed at a temperature of 150 to 200 ° C and a pressure of 30 to 35 MPa for 30 to 60 seconds. The temperature rise from the degreasing step to the heat treatment step is preferably carried out at a rate of 0.5 to 5.0 ° C / .

In addition, it is preferable that carbon is removed from the surface of the molded body in the heat-treating step and carbon remains in the core portion. Preferably, the degreased molded body is cooled to room temperature while being pressed by a flat press, and then heat-treated.

Since the ceramic blade manufactured by the method of the present invention is made of uniform fine particle ceramic, it is excellent in cutting power, light and hygienic, and can be easily manufactured by an injection molding method. Therefore, the conventional razor blade made of iron or a ceramic blade The manufacturing cost can be reduced.

In addition, since the hardness at the deep portion of the ceramic blade is high and the toughness at the surface is high, the surface damage can be suppressed while maintaining the strength of the entire blade, and the banding phenomenon can be prevented by eliminating structural irregularities inside the blade.

1 is a perspective view showing a state of a ceramic formed body after injection molding.
2 is a plan view showing a state of a ceramic formed body after injection molding.

Hereinafter, the present invention will be described in detail with reference to the following examples.

It should be understood, however, that the invention is not construed as being limited to the embodiments set forth herein, but is capable of modifications and equivalents within the scope of the appended claims. Will be apparent to those skilled in the art to which the present invention pertains.

The ceramic blade according to the present invention is manufactured by mixing a ceramic raw material with a polymer, injection-molding it, degreasing it, heat-treating it, and lapping it.

Ceramic is a compound that is stable at high temperature and rapid temperature change. It has a smaller specific gravity than iron material, so it has less force to cut hair. It has high compressive strength and can form sharp cutting surface. And is also hygienic because it is excellent in biocompatibility and does not cause inflammation reaction or allergy, has high corrosion resistance, and does not cause human harmful substances due to corrosion.

In order to apply the ceramic to a thin blade, it is preferable that the ceramic is a square yttrium oxide zirconia (Y ₂ O ₃ -ZrO ₂ ) which is partially stabilized with yttrium.

The yttria zirconia has high hardness and strength as well as high fracture toughness and abrasion resistance, unlike most other ceramics which are hard, strong and fragile.

The polymer is mixed in order to lower the viscosity during injection molding and to impart moldability and may be mixed with paraffin wax, low density polyethylene (LDPE), ethylene vinyl acetate (EVA) and stearic acid ), Or two or more thereof.

First, a plasticizer may be added to 70 to 80% by weight of the ceramic to 20 to 30% by weight of the polymer, and if necessary, a plasticizer may be added to facilitate the molding. The mixture of the ceramic and the polymer is heated do.

The ceramic is made of fine and uniformly ground ceramic powder, and the heating is to soften the polymer and uniformly mix with the ceramic, while stably forming the shape of the blade during injection molding to prevent defects.

Next, the ceramic and polymer mixture is injection molded to produce a ceramic blade shaped body.

The injection molding is preferably performed at a temperature of 150 to 200 ° C. and a pressure of 30 to 35 MPa for 30 to 60 seconds. If the injection molding temperature is lower than 150 ° C., the flowability of the ceramic and polymer mixture is low, If the temperature exceeds 200 ° C, degreasing of the polymer occurs during kneading of the ceramic and the polymer, and pores are formed in the molded body.

As described above, in the present invention, since the ceramic blade is manufactured through the injection molding method instead of the pressure molding method, it is possible to minimize the unevenness of the molding pressure that occurs during the molding, so that the occurrence of warpage and local sintering shrinkage due to non- The ceramic sintered body having dimensions similar to those of the block for a ceramic blade can be manufactured through injection molding. Thus, the pressure-molded sintered body can be cut, polished, cut, It is possible to reduce the manufacturing cost of the ceramic blade.

As shown in FIG. 1 (perspective view) and FIG. 2 (plan view), the ceramic blade body may be formed with a plurality of cutting portions for cutting hair by contacting the human skin. Shaving performance is better than shaving blade.

The molded article produced in the injection molding process may have a high brittleness, which may cause surface breakage during processing. In addition, the polymer component present in the molded article may cause voids or micro cracks in a heat treatment process, The degreasing process is carried out in order to lower the brittleness of the molded body and to cause ductility and to remove the polymer component of the molded body.

In the degreasing step, the shaped body is firstly heated at 100 to 150 ° C for 20 to 30 hours, then secondarily heated at 150 to 250 ° C for 20 to 30 hours, and then thirdly heated at 450 to 550 ° C for 20 to 30 hours And the thermal stress is suppressed in the molded body by the degreasing stepwise in this stepwise manner so that the bending phenomenon in which the molded body is warped is minimized and the polymer component present on the surface of the molded body is first degreased, Are sequentially degreased to suppress the occurrence of structural unevenness of the formed body due to degreasing.

If the temperature of the degreasing step is less than the above temperature and time range, the polymer may remain in the molded body and the ceramic blade may be damaged due to pores or cracks in the heat treatment step. If the temperature and time range are exceeded, The molded body is liable to be bent or broken.

Next, the degreased compact is subjected to a heat treatment at 1500 to 1600 ° C for 1 to 2 hours to sinter the ceramic. The heat treatment temperature is preferably the temperature in consideration of diffusion of the ceramic particles and necking between the particles. If the heat treatment temperature is lower than the above range, the characteristics of the sintered body may deteriorate due to incomplete sintering. If the heat treatment temperature is higher than the above range, the mechanical properties may be deteriorated due to excessive grain growth.

The polymer is composed of an organic compound mainly composed of carbon, and the organic compound decomposes in the temperature range of the degreasing process or is bonded to oxygen and is discharged to the outside of the molded product to remove most of the organic compound. However, Such a carbon component can increase the hardness of the molded body to increase the strength of the ceramic blade, but it may increase the brittleness and cause surface damage during processing.

In the heat treatment step, decarbonization occurs in which the amount of carbon is reduced as the carbon of the molded body is oxidized. As described above, by performing the heat treatment at a high temperature (1500 to 1600 ° C) for a short time (1 to 2 hours) The carbon remains in the deep portion, and the hardness is high due to the residual carbon in the deep portion, and the toughness is increased due to the removal of carbon on the surface. Therefore, the surface hardness of the formed body is maintained high, Can be suppressed.

The rate of temperature rise to the temperature for the heat treatment is preferably 0.5 to 5.0 ° C / minute. If the rate of temperature rise is less than 0.5 ° C / minute, the temperature rise time is long and the productivity decreases. If the rate is more than 5.0 ° C / Thermal stress may be applied to the formed body.

The degreasing process and the heat treatment process can be continuously performed. That is, in the degreasing process, the third heated product is directly heated without being cooled, and is heat-treated, thereby ensuring the efficiency of the process and saving energy.

However, when the injection molded ceramic blade shaped body is heated to a high temperature in the degreasing step and the heat treatment step, uneven density of the formed body due to unevenness of the molding pressure which may occur during the injection molding and the thin thickness of the molded body may cause banding have.

As a method for preventing such a problem, the degreasing step and the heat treatment step can be discontinued, that is, the degreased molded article is cooled to a normal temperature while being pressed flat by a press having the same plane as a flat plate press, Whereby the banding of the ceramic blade can be prevented.

When the molded body heated at 450 to 550 ° C. is pressed by a flat press, the molded body is heated, so that it is naturally converted into a planar shape without structural distortion inside the molded body. When the molded body is cooled, a structurally uniform planar ceramic blade body So that the bending phenomenon of the molded body can be prevented even by heat treatment at a high temperature.

That is, the bending phenomenon of the ceramic blade body can be solved by pressing the plate-shaped press while eliminating the structural unevenness of the inside of the molded body through the process of heating, cooling and heating the injection-molded body, Since the thickness of the blade body is reduced, it is possible to easily control the thickness of the ceramic blade to be manufactured.

Next, the production of the ceramic blade is completed by lapping the heat-treated molded body and cutting the blades to sharpen the blades.

The ceramic blade of the present invention manufactured as described above can be easily manufactured by an injection molding method, so that manufacturing cost can be reduced as compared with a conventional razor blade made of iron material or a ceramic blade made by press molding, Since the toughness is high, the occurrence of breakage on the surface can be suppressed while maintaining the hardness of the entire blade.

Claims (7)

Mixing the mixture of 70 to 80% by weight of the ceramic and 20 to 30% by weight of the polymer by heating to 150 to 180 캜;
Preparing a ceramic blade shaped body by injection molding the heated mixed mixture;
A degassing step of firstly heating the molded body at 100 to 150 ° C for 20 to 30 hours, then secondarily heating at 150 to 250 ° C for 20 to 30 hours, and then thirdly heating at 450 to 550 ° C for 20 to 30 hours;
Subjecting the degreased molded body to a heat treatment at 1500 to 1600 ° C for 1 to 2 hours; And
And lapping the heat-treated molded body to form a blade. The method according to claim 1,
Wherein the ceramic is a square yttrium oxide zirconia partially stabilized with yttrium. The method according to claim 1,
Wherein the polymer is at least one selected from the group consisting of paraffin wax, low density polyethylene, ethylene vinyl acetate and stearic acid. The method according to claim 1,
Wherein the injection molding is performed at a temperature of 150 to 200 DEG C and a pressure of 30 to 35 MPa for 30 to 60 seconds. The method according to claim 1,
Wherein the carbon is removed from the surface of the molded body and the carbon remains in the core at the heat treatment step. The method according to claim 1,
Wherein the temperature elevation from the degreasing step to the heat treatment step is performed at a rate of 0.5 to 5.0 DEG C / minute. The method according to claim 1,
Wherein the degreased molded body is cooled to a normal temperature while being pressed by a flat press, and then heat-treated.

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