JPH10330122A - Mold for glass molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mold for glass molding that scarcely causes flaw on-the molded glass surface by the press-molding in no need of application of a mold- releasing agent by forming, on the outermost surface of the mold base made of stainless alloy, a coated layer which is constituted with a combination of the areas of a metal-coated layer of an element in group 6 of the periodic table with the other areas of a metal-coated layer in which mold-releasing fine particles are dispersed in the matrix of an element in the iron group. SOLUTION: The coated layer is formed by combining the areas the layer A of a metal in group 6 of the periodic table (for example, Cr plated layer) with the other areas of the layer B in which fine particles manifesting mold- releasing properties, selected from (fluorinated) graphite, BN, carbon black, MoS2 , WS2 and CF2 are dispersed in the matrix of a metal in the iron group or an alloy mainly containing an iron-group element with an element selected from group 6 and Re (such as Ni matrix). In a preferred embodiment, the metal- coated layer A is formed on the areas in which the friction between the mold and the glass is reduced among the outermost surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding glass, especially for molding a CRT.

[0002]

2. Description of the Related Art A TV cathode ray tube is manufactured by separately forming a front panel, a funnel type funnel and a neck, applying a phosphor to the inner surface of the panel, attaching electrodes, and then combining them. Therefore, extremely strict quality control is required for the properties of the inner surface of the panel. In recent years, defects on the inner surface become apparent due to anti-reflection processing of the image display portion on the surface of the cathode ray tube, and the required quality tends to be higher.

[0003] The above-mentioned panel is formed by melting 1,000 pieces.
Metal mold (plunger) for glass at a high temperature of about ℃
This is done by pressing This mold is required to have properties such as mechanical strength, heat resistance, being chemically stable to high-temperature glass, and not generating defects such as minute cracks on the formed glass surface.

[0004] As a mold suitable for such a purpose, a mold in which chromium plating or nickel-tungsten alloy plating is applied on a stainless steel alloy has been frequently used. The chromium plating suitable for molds includes Sargent baths, mixed catalyst baths, and high-efficiency baths, but the surface of the glass formed on the side of the mold tends to be damaged during molding. There is a disadvantage that a release agent must be frequently applied.

On the other hand, when a nickel-tungsten plating film developed in recent years is used as a surface coating of a panel forming die, the occurrence of scratches on the side of the die is suppressed, and the frequency of application of a release agent is smaller than that of chromium. However, since the tungsten contained in the coating is easily oxidized and the mechanical strength at high temperatures is not always sufficient, the press-formed surface cannot be repaired in a shorter time than chromium when used at high temperatures for a long time. There is a disadvantage that uniformity tends to occur.

[0006] The present applicant has previously disclosed in Japanese Patent Application Laid-Open No. 8-188424.
Proposed a coating in which fine particles exhibiting releasability were dispersed in a nickel-based matrix coating as the outermost surface of a mold. In addition, for bottles, it is known to disperse graphite particles having lubricity from its own layered crystal structure in a nickel-based matrix coating (for example,
Japanese Patent Publication No. 7-35259). This type of coating has excellent mold release properties and improves the above-mentioned disadvantages on the side of the mold, but may be exposed to higher temperatures in regions other than the side of the mold. The life of the mold is inevitably shorter than that of chrome plating.

[0007]

In applying a release agent, this operation requires a high degree of skill. In addition, when the release agent separates from the mold and falls into the panel, it is applied to the panel surface. There is a problem that a defect may be caused, and there is a demand for the development of a mold that is durable at high temperatures and does not require the application of a release agent, or requires less application of the release agent.

[0008]

Means for Solving the Problems The present inventors have focused on the fact that the required properties of the coating differ depending on the part or position of the mold, and have found that even if the release agent is used less frequently, the glass surface is not damaged. We studied diligently for a glass molding die that is unlikely to occur.

As a result, a stainless steel base material is exposed to a relatively high temperature and easily oxidized, or a region where high mechanical strength at a high temperature is required, for example, light is transmitted from the panel or an image is projected and formed. In the region where the face part to be formed is formed, a metal film made of a Group 6 element is applied, and in the other region where the friction with glass is large, such as the side surface of the mold, fluorinated graphite, graphite, boron nitride, carbon, etc. Black, molybdenum disulfide, tungsten disulphide, calcium fluoride, or other fine particles dispersed inside, a dispersed plating film made of an iron group element, or an iron group element as a main component and selected from a group 6 element and rhenium By forming a combination with a dispersed plating film made of an alloy with more than one element, the conventional entire surface can be coated with chromium and nickel-tungsten. Or, compared to the mold that is a lubricated particle dispersed plating film, the glass surface is less likely to be scratched during press molding, the molding yield is improved, and it is used for a long time at high temperature with almost no release agent application during the molding operation In addition, the present inventors have found that the surface roughness of the molding surface of the mold is well maintained, and that the overall life of the mold is longer than that of the chromium film, and the present invention has been provided.

That is, the present invention relates to a group 6 element (ie, C
a region of the metal coating A made of one or more selected from r, Mo, and W) and an iron group element (that is, Fe, C
o, Ni or one or more selected from the group consisting of iron and a group 6 element and an alloy of one or more elements selected from rhenium. Provided is a glass molding die, wherein a coating layer formed by combining a region of a metal coating B in which fine particles are dispersed is formed on the outermost surface of a substrate made of a stainless alloy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below along with embodiments. The mold in the present invention is obtained by applying a coating or plating to a molding surface of a stainless steel alloy as a substrate. The glass mold can be applied to both the upper mold and the lower mold, but the upper mold (plunger) has a substantial advantage. This is because, in general, the use conditions of the lower mold are loose and the occurrence of defects due to the deterioration of the molding surface of the mold as described above is small. The mold of the present invention is suitable for a mold for producing glass products requiring high quality and strict optical characteristics, such as a cathode ray tube panel, with high yield among various molds for molding glass products.

The outermost surface coating (metal coating) of the mold to which the present invention is applied is made of a metal or an alloy.
Electroplating, chemical plating, CVD, PVD and thermal spraying can be applied. Electroplating is relatively low cost and is particularly suitable.

[0013] In a mold region where friction with glass is small during molding or a film is easily oxidized at a high temperature, for example, a mold region corresponding to a face portion of a cathode ray tube panel which transmits light or projects and forms an image. Is preferably a metal film made of a Group 6 element, and particularly preferably a metal film containing chromium as a main component from the viewpoint of oxidation resistance.

In the other region mainly on the side surface of the mold, a metal film in which fine particles exhibiting releasability are dispersed in a matrix is formed. As the matrix, an iron-group element or an alloy of the iron-group element as a main component and one or more elements selected from a group 6 element and rhenium is preferable. This is preferable in terms of ease of plating control and cost.

The fine particles dispersed in the coating include:
Particles such as graphite fluoride, graphite, boron nitride, carbon black, molybdenum disulfide, tungsten disulfide, and calcium fluoride are used. The presence of these fine particles has the effect of imparting lubricity at high temperatures of the coating and increasing the mechanical strength. In particular, graphite, boron nitride, and carbon black are preferable because they exhibit good lubricity up to around the glass forming temperature.

The concentration of these dispersed particles in the coating is 0.1 to 5 in order to obtain the above-described good lubricity.
0 vol% is preferable, and 5 to 30 vol% is more preferable.
The average particle diameter of the dispersed particles is preferably not more than the thickness of the outermost surface coating and 0.001 to 5 μm in order to form a plated film for obtaining a smooth molded surface. In order to form a flat molding surface with high precision suitable for a cathode ray tube panel or the like, 0.005 to 3 μm is more suitable for obtaining a plating surface suitable for glass molding.

Further, since carbon black is easier to pulverize than graphite or the like, which is known to have excellent releasability due to its layered crystal structure, carbon black is finer and finer in a matrix by a plating method. Since it can be uniformly dispersed, it is particularly suitable for a glass molding die having strict quality control standards for surface properties, from the viewpoint of enabling precise roughness control of the die surface. Carbon black is a particulate carbon material obtained by incompletely burning or thermally decomposing hydrocarbons such as natural gas and petroleum in the gas phase.Depending on the manufacturing method, carbon black, furnace black, thermal black, lamp black, rollers and rollers are used. It is roughly divided into disk black and the like. Further, those using acetylene as a raw material are called acetylene black, and any carbon black can be used in the present invention.

If the thickness of the coating on the outermost surface of the mold is less than 1 μm, it is susceptible to oxidation and mechanical deformation due to high temperature.
When the thickness is more than 00 μm, there is not much difference in the effect, and it takes a long time to form a film, which exceeds the technically and cost-effective range.

[0019] Between the mold substrate and the outermost surface coating, a group VIII, 9
By forming a thin film containing at least one metal selected from Group 10, Group 10 and Group 11 as an intermediate film or a base film, the bond between the substrate and the film is strengthened, and the outermost surface film is easily formed. become. One or more elements selected from Group 8 to Group 11 include iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver,
Gold is preferred. Usually, for example, nickel, cobalt, iron, chromium, palladium, etc. are plated,
It is manufactured by a thin film forming method such as VD or thermal spraying. In particular, the plating method is preferable in terms of the film formation speed, the film smoothness, the cost, and the like. In addition, these elements contain 40% as a main component.
It is preferable that the content be 100% or less in order to utilize the characteristics of these elements. This subcomponent is usually Ni-P or Ni-B, and impurities are also allowed as long as the film characteristics are not impaired.

In this case, the thickness of the thin film is 0.1 μm
If it is thinner, it is difficult to effectively cover the entire surface,
If the thickness is more than 50 μm, the residual strain increases and the meaning as an intermediate layer is lost, so that 0.1 to 50 μm is preferable. As a mold base, a martensitic stainless steel alloy is preferable in terms of mechanical strength, corrosion resistance, thermal conductivity, thermal expansion characteristics, and the like.

In the case where films suitable for these regions are selectively combined in different regions on the molding surface of the mold, one film is formed on the entire molding surface in order to facilitate the forming operation. After that, the other film may be formed so as to overlap a predetermined region of the film.

[0022]

The coating of the glass molding die of the present invention is in direct contact with the high-temperature molten glass and transmits or transmits light of a glass product part requiring the strictest surface precision quality, for example, a panel of a TV cathode-ray tube. By providing a metal coating with excellent oxidation resistance in the area corresponding to the face part where the image is projected and focused, stable surface accuracy is maintained for a long time, and scratches due to mutual contact with cooled molded glass By providing a metal film in which fine particles having lubricity are dispersed, that is, a dispersed film, in a region such as a mold side surface that is likely to occur, the frequency of release agent application is significantly reduced so that it becomes almost unnecessary, and the mold is formed. And improve the molding yield.

Although the reason why the effect of the dispersed film is obtained is not clear, the contact between the dispersed particles and the molten glass is made by the particles dispersed in the film by dispersing and fixing the dispersed particles in a metal. Therefore, the interfacial energy is significantly different from the oxidized surface of the matrix metal or alloy, making it difficult to wet, and because it is brittle compared to the matrix, a small amount of it is supplied from the dispersed particles to the interface with the glass surface at the time of molding. It is considered that this acts as a lubricant.

Further, the dispersion coating of the present invention has improved mechanical strength at high temperatures as compared with conventional coatings. Although the reason is not necessarily clear, the above-mentioned dispersed particles are dispersed and fixed in the metal, whereby the deformation of the matrix at high temperatures is suppressed, and the action of fine irregularities due to the dispersed particles and the dispersion particles are prevented. Due to the lower thermal conductivity compared to the matrix, thermal contact with the molten glass, heat conduction is reduced,
It is considered that the temperature rise of the mold is substantially suppressed.

[0025]

Examples Examples of the present invention (Examples 1 and 2) and comparative examples (Examples 3 and 4) are shown below, but the present invention is not limited to these. These examples were performed using a mold (plunger) for forming a CRT panel shown in FIG. In the figure, 1 is a substrate, 2 is a mold side surface, 3 is a face forming surface of a panel, and these 2 and 3 are forming surfaces.

(Example 1) SUS420J2 (JIS-G4
303) After forming a chromium plating film having a thickness of 10 μm on the entire surface of the substrate using an aqueous solution containing chromium sulfate as a main component, boron nitride having an average particle diameter of 0.3 μm is used as a dispersant in a nickel watt bath. Using the bath to which the dispersion was added, an outermost surface coating having an average film thickness of 10 μm and containing 20% by volume of boron nitride was formed using nickel as a matrix only on the side surfaces of the mold. Glass molding was performed using this mold, and the incidence of microcracks and micro-abrasions generated in the glass molded body due to contact with the side surface of the mold, the frequency of release agent application, and the continuous usable time of the mold were examined. Table 1 shows the results.

(Example 2) SUS420J2 (JIS-G4
303) The surface of the substrate is 1.5
A nickel layer having a thickness of 3 μm is deposited as a dispersing agent only on the side of the mold, and then dispersed in a plating solution containing nickel sulfate, sodium tungstate, and citric acid as main components. A nickel-tungsten alloy (68% by weight: 32% by weight) is used as a matrix to form a 9 μm thick outermost film containing 35% by volume of graphite, and chromium oxide, molybdenum oxide,
Using an aqueous solution containing ammonium citrate and chromium sulfate as its main components, a chromium-molybdenum alloy (88
(% By weight: 12% by weight). Glass molding was performed using this mold, and the incidence of microcracks and micro-abrasions generated in the glass molded body due to contact with the side surface of the mold, the frequency of release agent application, and the continuous usable time of the mold were examined. Table 1 shows the results.

(Example 3) SUS420J2 (JIS-G4
303) On the surface of the substrate, a 10 μm-thick outermost film made of chromium with chromium sulfate as its main component was formed. Glass molding was performed using this mold, and the incidence of microcracks and micro-abrasions generated in the glass molded body due to contact with the side surface of the mold, the frequency of release agent application, and the continuous usable time of the mold were examined. Table 1 shows the results.

(Example 4) SUS420J2 (JIS-G4
303) 4 μm on the surface of the substrate using a nickel chloride bath
A thick nickel layer is deposited, and then, a liquid having nickel sulfate, sodium tungstate, and sodium citrate as main components is crushed to reduce the average size of the long side to 8%.
11 μm-thick graphite-dispersed nickel-tungsten alloy (70 wt%: 3)
0% by weight). Glass molding was performed using this mold, and the incidence of microcracks and micro-abrasions generated in the glass molded body due to contact with the side surface of the mold, the frequency of release agent application, and the continuous usable time of the mold were examined.
Table 1 shows the results.

In Examples 1 to 4, the CRT panel glass was 62.0% by weight of silicon oxide, 7.5% by weight of sodium oxide, 8.1% by weight of potassium oxide, 11.6% by weight of strontium oxide, and 2.2% by weight of barium oxide. % And other 8.6% glass such as zirconium oxide.

In Table 1, various evaluations of the probability of occurrence of microcracks, minute scratches on the mold side surface, the frequency of release agent application, and the continuous usable time of the mold are shown by relative values when Example 3 is set to 10. ing.

[0032]

[Table 1]

[0033]

As can be seen from the examples, the outermost surface of a die made of a stainless steel alloy is coated with a metal film made of a Group 6 element and a metal film made of an iron group element or containing an iron group element as a main component. And a metal coating in which fine particles exhibiting releasability are dispersed in a matrix made of an alloy of one or more elements selected from Group 6 elements and rhenium, and selectively combined with the position of the mold. By forming the film, the release property is superior to that of the conventional chromium film, the application of the release agent is almost unnecessary, and the glass surface is not damaged. Further, the mechanical strength at high temperatures is superior to that of the nickel-tungsten coating, and the effect of maintaining a smooth surface property for a long time can be obtained. Thereby, the durability of the whole mold is improved, and high quality glass products can be produced with good yield.

[Brief description of the drawings]

FIG. 1 is a side view of a mold used in an embodiment of the present invention.

[Explanation of symbols]

 1: Base 2: Mold side surface 3: Face molding surface

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiromi Katsuta 1150 Hazawacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture, Central Research Laboratory of Asahi Glass Co., Ltd.

Claims (9)

[Claims] 1. A matrix comprising a region of a metal coating A comprising a Group 6 element and an alloy comprising an iron group element or one or more elements selected from a Group 6 element and rhenium, which contains an iron group element as a main component. A coating layer formed by combining a region of the metal coating B in which fine particles exhibiting releasability are dispersed,
A glass forming mold formed on the outermost surface of a substrate made of a stainless alloy. 2. The metal coating A is formed in a region of the outermost surface where friction between the mold and the glass is small.
The glass molding die according to the above. 3. The glass molding die according to claim 1, wherein said coating layer has a thickness of 1 to 500 μm. 4. The glass molding die according to claim 1, wherein said fine particles are at least one selected from graphite fluoride, graphite, boron nitride, carbon black, molybdenum disulfide, tungsten disulfide and calcium fluoride. 5. The glass molding die according to claim 1, wherein the average particle diameter of the fine particles is not more than the thickness of the metal coating B and is 0.001 to 5 μm. 6. The method according to claim 1, wherein the concentration of the fine particles in the metal film B is 0.1.
The glass molding die according to claim 1, wherein the amount is from 50 to 50% by volume. 7. Group 8 or 9 between said substrate and said coating layer.
The glass molding die according to claim 1, comprising a thin film containing one or more elements selected from Group 10, Group 11, and Group 11 as main components. 8. The glass molding die according to claim 7, wherein said thin film has a thickness of 0.1 to 50 μm. 9. The glass forming mold according to claim 1, wherein said base is a martensitic stainless steel alloy.