JPS6230660A - Blade of razor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blade used in a consumer razor, and more particularly to a razor blade made of ZrO2 ceramics.

[Conventional technology]

Razor blades are mainly made of 1%C-13%Cr2N, 0.
Stainless steel such as 65% C-13xCr steel is used.

This stainless steel razor blade is easy to machine, can be sharpened at a sharp angle, and has good initial sharpness. However, since stainless steel has low hardness, it wears easily, and the tip of the blade that has penetrated into the whiskers may undergo plastic deformation or chipping due to the bending stress from the whiskers, resulting in a significant decrease in sharpness and a lack of durability. There was a problem.

In recent years, cutlery made of ZrO2 ceramics, which is wear-resistant, has high mechanical strength, and is durable, has attracted attention as a tool that can overcome the drawbacks of metal cutlery. Razor blades are no exception, and it is said that various studies have been conducted.

[Problem that the invention seeks to solve]

However, the current situation is that no satisfactory razor blade has been developed.

An object of the present invention is to provide a razor blade that has excellent sharpness and can maintain its sharpness over a long period of time.

[Means to solve the problem]

As mentioned above, in recent years, ZrO2 ceramics having a tetragonal crystal structure have been found to exhibit high strength and high toughness at room temperature, and have attracted attention as structural materials.

As a result of intensive studies on ZrO2 ceramics, the present inventor found that when the ceramic has a specific crystal structure in a specific proportion or more and the crystal grain size is suppressed to a specific value or less, the sharpness and durability of a razor blade are significantly improved. This is what I discovered.

That is, the object of the present invention is achieved by a razor blade made of ZrO2 ceramic having a tetragonal crystal structure of 90% or more and a crystal grain size of 1 μm or less.

If the proportion of tetragonal crystals is less than 90%, strong mechanical properties cannot be obtained, and the blade has a lot of chipping during processing, making it difficult to achieve a sharp cutting edge and making it impossible to obtain the desired sharpness. Therefore, it is necessary to have a tetragonal crystal structure of 90% or more.

Suppressing the crystal grain size of ZrO2 ceramics to 1 μm or less is an important requirement in order to obtain durability of sharpness. After examining it from various angles, they discovered that there is a correlation between the presence or absence of chipping on the cutting edge, sharpness, and durability.

In other words, if the chipping of the cutting edge is minimized and reduced, the durability of the cutting edge will be significantly improved. By suppressing the crystal grain size to 1 μm or less, this chipping can be suppressed to a level that does not cause any problems with durability.

By the way, in order to make the tetragonal crystal structure 90% or more, it can be achieved by adding any one of Y2O32-4 mol% and CeO26-13 mol%. If the amount added is less than these amounts, the proportion of monoclinic crystals will increase, and if it is less, the proportion of cubic crystals will increase, so in any case, the proportion of tetragonal crystals will be less than 90%, making it impossible to obtain strong mechanical properties.

Although the purpose of the present invention can almost be achieved with the above razor blade made of ZrO2 ceramics, it is preferable that the shape of the cutting edge is such that the cross-sectional angle of the cutting edge is in the range of 10 to 30 degrees from the tip to at least 50 μm. The smaller the angle of the cutting edge, the better the sharpness, but the strength of the cutting edge becomes weaker, which reduces durability.

Furthermore, the smaller the angle of the cutting edge, the better the cutting quality, but the strength of the cutting edge becomes weaker, which reduces durability. Further, if the angle of the cutting edge is less than 10 degrees, chipping will increase and machining of the cutting edge will be difficult. Conversely, the larger the angle of the cutting edge, the better the durability, but the sharpness decreases.

Therefore, it is preferable that the angle of the cross section of the cutting edge from the tip of the cutting edge to 50 μm is in the range of 10 to 30 degrees. (Hereinafter, when we refer to the angle of the cutting edge, it refers to the range of at least 50 μm from the tip of the cutting edge.) The shape of the cutting edge may have a two-step or three-step angle; The angle also needs to be within this range.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

Example 1 Zr with an average particle size of 0.1μ containing 3 mol% of Y2O3 as a solid solution
The raw material powder of O2 and pure water are each placed in a pot and mixed for 20 hours using a ball mill, then polyvinyl alcohol is added as a binder, and the mixture is further mixed for 5 hours to form a slurry. The slurry is dried and granulated using a spray dryer, and then filled into a rubber mold. 3 tonf/cn for this rubber mold? The granulated powder is compacted by applying pressure to obtain a molded body.

After degreasing the obtained molded body at 600°C in the air, 1
00°C, the temperature was increased at a rate of lhr, and the temperature was increased to 1480°C for 1. hr
Hold and sinter. The obtained sintered body was subjected to a pressure of 1500 kg.
t/cnf.

Further densification was achieved by applying HIP (hot isostatic pressing) at a temperature of 1400° C. for 11 hours. The crystal grain size of this final sintered body was 0.4 μm, and the crystal structure was 97% tetragonal. This sintered body was sliced to obtain various razor blades having a blade thickness of 0.1+nm and a cutting edge angle of 8 to 40 degrees. These razor blades were used to perform hair cutting test 1. The results are shown in Table 1.

When the cutting edge angle was set to 8 degrees, there was a problem in the workability of the cutting edge, that is, the cutting edge frequently chipped, and was not suitable for practical use. On the other hand, the cutting edge angle is 35.40
In the case of sharp edges, there was no problem with the workability of the cutting edge, but the sharpness was significantly inferior. In addition, with a cutting edge angle of 10 degrees, although the cutting edge workability and cutting quality are quite satisfactory, the cutting edge strength is poor, so there are some problems in durability. As shown in 2 below, the cutting edge angle should be 10 to 30 degrees, more preferably 15 to 30 degrees, considering the workability, sharpness, and durability of the cutting edge.
It is necessary to be within the range of

Table 1 Example 2 Using ZrO2 raw material powder containing 2.5 mol% of Y2O as a solid solution, ZrO2 with various crystal grain sizes was produced using the same manufacturing method as in Example 1.
rO2 ceramics were obtained. This ZrO2 ceramic has a blade thickness of 0. II@, a razor blade with a cutting edge angle of 20 degrees was prepared, and its workability, sharpness, and durability were evaluated. Second
The results are shown in the table.

Table 2 When the crystal grain size is 0.2.1.0 μm, which is within the range of the present invention, the workability of the cutting edge is excellent, chipping is reduced,
Both sharpness and durability are good. On the other hand, the grain size is 1.2
．． In the case of 2.0 μm, both the sharpness and durability are poor, and the deterioration in durability is particularly significant. As described above, it can be seen that the crystal grain size has a large effect on cutting quality and durability, and that it is important to suppress the crystal grain size to 1 μm or less in order to achieve the object of the present invention.

Furthermore, the same results as in Example 1.2 were obtained with ZrO2 ceramics containing 10 mol% of CeO2 as a solid solution.

〔Effect of the invention〕

As explained above, in the present invention, ZrO2 ceramic tin razor blades are made practically sufficient by having a specific crystal structure in a specific proportion or more and suppressing the crystal grain size to a specific value or less. is possible and very useful industrially.

Procedural amendment (voluntary) ・;- 1. Indication of the case 1985 Patent Application No. 168162 2. Name of the invention Razor blade 3. Relationship with the person making the amendment Patent applicant address Chiyoda, Tokyo 2-1-2 Marunouchi Ward Name (508) Hitachi Metals Co., Ltd. 4
, Detailed description of the invention in the specification to be amended.

5. Contents of amendment (1) “Pressure 1500 kgt/a” on page 6, line 9 of the specification
Correct JJ to [pressure 1500 atmJ.

(2) Replace Table 1 on page 7 of the same book with the attached Table 1.

(3) Replace Table 2 on page 8 of the same book with the attached Table 2.

Table 1 Table 2

Claims (1)

[Claims] 1. Having at least 90% tetragonal crystal structure;
A razor blade characterized by being made of ZrO_2 ceramics having a crystal grain size of 1 μm or less. 2 Claim 1 containing any one of Y_2O_32 to 4 mol% and CeO_26 to 13 mol%
Razor blade as described in section. 3. The razor blade according to claim 1 or 2, wherein the angle of the cross section of the cutting edge from the tip of the cutting edge to at least 50 μm is in the range of 10 to 30 degrees.