JPH0645219B2 - Manufacturing method of plastic processed products with coating of fluorine resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is to produce a molded article having a coating of fluorine resin on a rolled metal plate and then subjecting it to plastic working to produce a coating of fluorine resin on the surface. It is about how to do it.

<Prior Art> Fluorine-based resins are excellent in heat resistance, chemical resistance, non-adhesiveness, and the like, and have been conventionally prized for various uses by taking advantage of these characteristics. For example, many kitchen appliances such as an inner pot of a rice cooker and a frying pan have an inner surface coated with a fluororesin.
These kitchen appliances are manufactured by coating a rolled metal plate with a fluorine-based resin, and then subjecting it to a predetermined shape by subjecting it to drawing or other plastic working.

<Problems to be Solved by the Invention> It is desired that kitchen appliances such as an inner pot of a rice cooker display a scale as a guide for putting contents or characters for instructing use. For example, in the inner pot of a commercially available rice cooker,
On the side wall, the scale of water corresponding to the amount of rice is engraved. This scale is formed by forming an inner pot by drawing from a resin-coated disc and then stamping it with a marking machine. However, the marking by such marking has a defect that the molded product is distorted and the resin coating is damaged. Further, it is difficult to say that only a simple display such as a scale line can be given, and the display itself is not always easy to see.

As a method of giving a display instead of a marking, there is a method of coloring. That is, a desired indication is given to the surface of the rolled metal plate with a paint (ink) containing a coloring agent and then coated with a fluororesin (see Japanese Patent Application No. 1-240865), or a coating with a fluororesin is applied. It is a method of imparting desired display with a coating material containing a colorant (see Japanese Patent Application No. 1-286866). According to this method, it is possible to easily give the display without the above-mentioned defects, but the display is deformed when the portion where the display is present is stretched by plastic working. Therefore, the indication is given assuming the state after plastic working, but experience shows that the deformation due to plastic working is not always constant, so the indication on the molded product (hereinafter, the deformation due to plastic working There is inconvenience that variations occur in the original display in order to distinguish the previous display from the display on the molded product.

The present invention is such that the deformation due to plastic working is always constant,
That is, it is intended to provide a method of giving a display having good reproducibility even after plastic working.

<Means for Solving the Problem> The present inventors cut out a circular plate from a long metal rolling plate by punching, and gave a large number of the same original markings radially around the circular center. As a result of studying how each original display deforms when drawn around the center of the circle, the degree of deformation and its reproducibility are determined by the rolling direction of the metal plate and the presence of the original display. It was found that it depends on the relationship with the position. It has been found that, when the original display is applied at a fixed position determined by the type of the metal plate with respect to the rolling direction of the metal plate, a desired display can be reproducibly displayed on the molded product after the drawing process.

The present invention has been achieved based on the above knowledge,
By making an original indication at a predetermined position on the surface of the metal plate that is determined based on the rolling direction of the metal plate, the indication on the molded product after plastic working caused by this deformation is always constant Is.

The present invention will be described in more detail. In the present invention, the coating itself with the encapsulating resin can be performed by a conventional method. As the rolled metal plate, a steel plate, a stainless steel plate, an aluminum plate, an aluminum alloy plate or a clad plate of these is used. These rolled plates are subjected to appropriate pretreatments such as degreasing, chemical conversion treatment and surface roughening treatment by a conventional method before forming a coating on the fluororesin. Among them, the roughening treatment is effective in increasing the adhesion between the rolled plate and the fluorine-based resin, and it is used for etching treatment such as chemical etching and electrolytic etching, and for machines such as barrel grinding method, hairline method and shot blasting method. Surface roughening treatment, and further, these treatment methods are appropriately combined. The degree of surface roughening is 0.5 to 0.5 in terms of average roughness (Ra).
The range is 5 μm, but the range of 1 to 3 μm is preferable.

In the present invention, the rolled plate which has been subjected to the appropriate pretreatment is provided with an original indication and then formed with a coating of a fluorine-based resin, or after forming a coating with a fluorine-based resin and then the original indication is formed thereon. However, the shape of the marking must be determined in consideration of the deformation due to the subsequent plastic working. Further, the position where the original marking is applied on the rolled plate must be determined so as to be a fixed position in relation to the rolling direction. Explaining this with reference to the attached drawings, FIG. 1 shows a rolling direction that passes through the center of the disc on a disc manufactured by punching from a rolled plate of aluminum alloy to manufacture the inner pot of the rice cooker. Parallel to (a), 22.5 ° (b), 45 ° (c) and 9
On each straight line of 0 ° (d), an original scale indicating the position of water is attached. When deep drawing is performed on this, an inner pot having scales on the side wall is obtained. However, the state of the scale and its reproducibility differ depending on which of (a) to (d) the scale is attached. It depends on the type of rolling plate that the original scale is applied to obtain a good-quality scale on the side wall with good reproducibility.
That is, it is determined by the composition, heat treatment conditions and the like. For example, in the case of an aluminum-manganese alloy in which 1% of Mn is added to aluminum, the original scale is provided in parallel with the rolling direction or in the direction perpendicular to the rolling direction, that is, on the straight line of (a) or (d) in FIG. Was found to be preferable. Further, in the case of the aluminum-manganese-magnesium alloy in which 1% of Mg is further added to the aluminum alloy in which Mn is added, it is 22.5 ° with respect to the rolling direction, that is, it is on the straight line of (b) in FIG. It has been found preferable to calibrate. As to which direction to apply the original scale to the rolling direction, the original scale is formed on a radial straight line passing through the center of the disc as shown in Fig. 1, and the original scale is drawn by drawing into a predetermined shape. It suffices to select a direction that minimizes the degree of deformation. It is preferable to apply the original scale to the image in the direction in which the ear is minimized due to the drawing process.

In the case of a long rolled plate, since the direction of the rolled plate is the rolling direction, it is easy to determine the position of the original display so as to be a predetermined position with respect to the rolling direction. However, in a rolled plate cut out from a long rolled plate into individual plastic working units such as a disc, it is desirable to give some indication to the rolled plate to indicate the rolling direction. For example, it is possible to display in advance on a long rolled plate a paint which can easily erase the rolling direction in advance. Considering the convenience of the subsequent process of giving the original marking, when cutting individual rolled plates of a plastic working unit from a long rolled plate, an instruction to indicate the rolling direction such as a protrusion or notch on the periphery of the rolled plate. It is preferable to provide a part. For example, FIGS. 2 and 3 show an example in which protrusions (1) are provided in parallel or at right angles to the rolling direction,
FIG. 4 shows an example in which two protrusions (1) are provided in the direction of 45 ° with respect to the rolling direction.

If such an indicator is provided on the peripheral edge, when the original display is made on the rolled plate by screen printing, for example, the rolled plate is fitted to the support base having the concave portion to which the rolled plate fits and the printing is performed. When the mark is applied, the original display is automatically applied at a fixed position in the rolling direction. Therefore, it is not necessary for a human to judge the rolling direction, and the work can be automated.

In order to give the original marking on the rolled plate before forming the coating with the fluorine-based resin, it is easiest to form the original marking by printing or other method using a paint (ink) containing a colorant. . As the coating material, one that has excellent adhesion to the rolled plate and does not deteriorate during subsequent formation of a coating of a fluorine-based resin or other processing is used. For example, when forming an original display on a rolled plate of aluminum alloy, applying polytetrafluoroethylene coating, deep drawing, and further anodizing to make a rice cooker, baking of polytetrafluoroethylene and alumite Use one that has heat resistance, corrosion resistance, and chemical resistance so that it does not deteriorate during treatment and can withstand use as a rice cooker. Furthermore, it is desirable that the coating material has a good affinity with the fluororesin applied thereon. Usually, a mixture of a heat-resistant polymer having a polar group that provides adhesion and heat resistance with a metal dissolved in a solvent, and fine particles of a fluorine-based resin and an inorganic or organic colorant are appropriately mixed. . The reason why the fluorine-based resin is blended is to improve the affinity with the fluorine-based resin applied on the original display. When a soluble fluorine-based resin is used, it itself can be used as a film-forming component. Further, instead of using a colorant, a polymer compound that discolors or turns black due to thermal deterioration during the subsequent heat treatment can be used to form the original display.

As the heat resistant polymer, for example, polyimide, polyamide imide, polyether sulfone, polyphenylene sulfide, epoxy resin or the like is used. As the colorant, for example, copper phthalocyanine blue, phthalocyanine green, titanium oxide, red iron oxide, carbon black or the like is used.

A screen printing method is usually used as a method of forming the original display. The paint year is usually 10 to 200 poise, preferably 20 to 100 poise. The viscosity can be easily adjusted by changing the concentrations of the heat resistant polymer and the fluororesin. The coating film formed on the rolled plate is preferably as thin as possible.
It is 5 μm.

After the paint is applied on the rolled plate by printing or the like, it is sufficiently dried to remove volatile components. If the volatile component remains, swelling or the like may occur in the coating when the coating of the fluororesin applied thereon is baked. Although it depends on the components of the paint, it is usually sufficient to maintain the temperature at 250 to 300 ° C. for about 10 minutes.

The shape of the original display needs to be set so that a predetermined display can be obtained after plastic working, and can be easily determined by performing trial and error a few times. When the original display covers a large area, it is particularly preferable to use a paint that is well compatible with the coating of the fluororesin formed thereon.

As another method of forming the original marking on the rolled plate, in the case of aluminum or aluminum alloy, after masking a portion other than the original marking, a method of anodic oxidation-AC electrolytic coloring, a chemical method using ammonium molybdate, etc. Any known coloring method such as a method of coloring by treatment can be used. The original display can also be formed by etching or plating.

Next, a fluororesin-based coating is formed on the rolled plate having the original marking. This coating must enable visual recognition underneath after plastic working, but to the extent that this condition is satisfied, colored mica and other pigments are mixed in the coating to form a colored coating. It can also be formed.

In any case, it is preferable to use a fluorine-based resin that gives a coating having a total light transmittance of 40 to 100% specified by JIS K-7105 in a predetermined thickness formed on the rolled plate. Usually, it is preferable to use the clear fluororesin as it is.

As the fluorine-based resin, polytetrafluoroethylene,
Tetrafluoroethylene-perfluorovinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, room temperature reaction-curable fluoroethylene-hydrocarbon-based vinyl ether copolymers, and other commonly used fluorine-based resins for coating formation Can be used. Preferably, polytetrafluoroethylene or a room temperature reaction-curable fluoroethylene-hydrocarbon-based vinyl ether copolymer is used.

The fluororesin coating can be formed in several ways. One of them is a method using a dispersion liquid of a fluorine resin. That is, a fluorine-based resin is applied to a rolled plate as a dispersion prepared by dispersing it in an appropriate liquid medium such as a mixed solution of water and a surfactant or a mixed solution of water, toluene and a surfactant, and then depending on the characteristics of the resin. A rolled plate coated with a fluorine-based resin can be obtained by curing at a low temperature of about room temperature or heating at a high temperature and baking.

As a method for applying the fluorine-based resin, any known method such as a spray method, a flow coating method, a roll coating method, a spin coating method or a die coating method can be used. A spray method, a spin coating method, a flow coating method, or the like is used when the coating is applied to the disc as in the case of manufacturing the inner pot of the rice cooker. The thickness of the coating film is preferably about 5 to 100 μm as a cured or baked coating film. The temperature conditions for curing or baking change depending on the type of fluorine-based resin, but the following temperature conditions are usually applied to the above-mentioned resins.

Polytetrafluoroethylene 350 to 450 ° C. Tetrafluoroethylene-perfluorovinyl ether copolymer 300 to 400 ° C. Ethylene-tetrafluoroethylene copolymer 300 to 400 ° C. Fluoroethylene-hydrocarbon-based vinyl ether copolymer Normal temperature to 250 ° C. The coating film of the fluoroethylene-hydrocarbon-based vinyl ether copolymer can be cured even at room temperature by reacting on the basis of a carboxyl group or a hydroxyl group derived from the hydrocarbon-based vinyl ether and introduced into the copolymer. However, when it takes a long time to cure at room temperature, heating can accelerate the curing. For example, it can be cured at 140 ° C. for about 30 minutes and at 180 ° C. for about 10 minutes.

The second method for forming the coating of the fluorine-based resin is to press the preformed sheet of the fluorine-based resin onto the rolled plate with the original marking, and then heat and sinter the rolled sheet to the rolled plate. This is a method of bringing them into close contact. As the fluorine-based resin, it is possible to use a sheet-shaped product of the above-mentioned one, and for example, the one commercially available as Aflex from Asahi Glass Co., Ltd. is used.

In the present invention, instead of forming the original display on the rolled plate and then forming the coating of the fluorine-based resin, it is also possible to form the original display on the formed coating of the fluorine-based resin on the rolled plate. . Also in this case, the formation of the fluorine-based resin coating itself can be performed in exactly the same manner as described above. However, unlike the above-mentioned case, the property that the display can be visually recognized through the coating is not required, and therefore an opaque coating can be used. Therefore, it is also possible to blend titanium oxide, colored mica, or the like in the clear fluororesin dispersion to conceal the base rolled plate.

When forming the original display with paint on the coating of fluorine resin,
The fluororesin coating is difficult to handle unless it is baked beforehand to make it strong. However, the firing does not have to be complete. For example, firing may be performed at an intermediate temperature of about 270 to 300 ° C. to form a coating having a temporary strength, and firing may be performed at the maximum temperature after forming the original display.

When forming an original display on a coating of a fluororesin with a paint containing a colorant, a method for directly forming the original display on the rolled plate including selection of the position and shape of the original display A method similar to can be used. That is, it is necessary to determine the position of the original display based on the rolling direction, and the shape is determined so as to have a predetermined shape after plastic working.
Screen printing is suitable as a method for forming the original display. It is preferable that the coating material has excellent adhesion to the fluorine-based resin coating and excellent coloring clarity. Usually, like the above-mentioned ones, a polymer compound having excellent adhesion to a fluorine-based resin such as polyimide, polyamide-imide, polyether sulfone, polyphenylene sulfide, and epoxy resin is dissolved in a solvent, and fine particles of the fluorine-based resin and A mixture of an inorganic or organic colorant is used. As the colorant, copper phthalocyanine blue, phthalocyanine green, red iron oxide, titanium oxide, carbon black and the like are used as in the above. After printing, it is baked to bring the coating into close contact with the paint. The coated rolled plate obtained by coating the rolled plate with the original marking and the fluorine-based resin is then subjected to a drawing process or other plastic working by a conventional method to obtain a molded product having a desired shape.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Aluminum alloy containing 1% Mn (JIS-A3003
From equivalent rolled plate (thickness 1mm) by press 43
A 0 mm disc was punched out. Shot blasting and chemical etching treatments were applied to this disc to obtain an average roughness (Ra) of 2.
It was a 0 μm roughened disc. On this roughened disc,
As shown in FIG. 1, scales were formed by screen printing in the rolling direction (a) and in the direction (d) perpendicular to the rolling direction using a paint having the following composition (viscosity of 30 poise). 180 ° C
After being dried in a dry state, an aqueous dispersion of polytetrafluoroethylene (resin concentration 60% by weight) was applied by an air spray method, dried and then heated at 380 ° C. for 10 minutes and baked to obtain a fluorine resin-coated disk. .

Table 1 Composition of coating Polyimide 30 (weight) part Polytetrafluoroethylene 70 〃 N-methylpyrrolidone 50 〃 Copper phthalocyanine blue 0.5 〃 The diameter of the bottom of this resin coated disk is 200m
It was molded into a cylindrical container having m and a height of 150 mm. On the side surface of the obtained container, a clear blue scale without distortion was formed at a predetermined position. Twenty identical cylindrical containers were manufactured, but the scale shapes were the same. No damage or other defects were found in the resin coating of the cylindrical container.

For comparison, the direction of 45 ° to the rolling direction (C)
A cylindrical container was manufactured in exactly the same manner as in Example 1 except that the scale was formed by screen printing, and the shape of the scale varied and was not constant, resulting in poor reproducibility.

Example 2 Using an aluminum alloy containing 1% of Mn and 1% of Mg, respectively, and using a paint having the composition shown in Table 2, as shown in FIG. Twenty cylindrical containers were manufactured in exactly the same manner as in Example 1 except that the scales were formed on. In each of the containers, a scale having the same shape and having no distortion was formed at the same position on the side wall. No damage or other defects were found in the resin coating.

Table 2 Epoxy resin 30 (weight) part Methylethylimidazole 2 Polytetrafluoroethylene 70 N-Methylpyrrolidone 50 Copper phthalocyanine blue 0.5 Butylcellosolve 50 Example 3 In Example 1, polytetrafluoro was added to the roughened disk. An aqueous dispersion of ethylene (resin concentration 60% by weight) was applied by an air spray method, dried and then heated at 380 ° C. for 10 minutes and baked. On the fluorine resin coating, the same coating material as in Example 1 was used to form scales by screen printing in the direction parallel to the rolling direction (a) and in the direction perpendicular to the rolling direction (d), dried and then heated. To bring the coating into intimate contact with the coating. This was deep-drawn in the same manner as in Example 1 to obtain a cylindrical container. A clear scale without distortion was formed on the side surface of the container. Twenty of the same containers were manufactured, but the scale shapes were the same. No damage or other defects were found in the resin coating.

<Effect> According to the present invention, it is possible to easily manufacture a container having a scale or other desired display and having a surface coated with a fluorine-based resin. Therefore, the present invention provides a cooking device such as a rice cooker, a bread maker, a rice cake maker, a hot plate, a pan, and a frying pan covered with a fluorine-based resin and having a non-adhesive surface with an indication necessary for cooking such as the amount of water and ingredients. Useful to do.

[Brief description of drawings]

Fig. 1 shows a disc cut from a rolling plate, passing through the center of the circle and on a straight line of 0 ° (a), 22.5 ° (b), 45 ° (c) and 90 ° (d) with respect to the rolling direction. It shows a state in which a scale is formed at the position. The arrow passing through the center of the circle in the figure indicates the rolling direction. 2 to 4 show a disc having a protrusion (1) provided on the periphery to indicate the rolling direction.

Claims (9)

[Claims] 1. A method for producing a molded article having a coating of fluorine resin on the surface of a rolled metal sheet, and then subjecting this to plastic working to produce a molded article having the coating of fluorine resin on the surface, in which the rolling direction of the metal sheet is set. After a predetermined original marking is given at a predetermined position on the surface determined based on the above, a fluororesin coating is formed on the surface so that the finally formed marking can be visually recognized, and then the plasticity is applied. A method for producing a molded article having a desired display derived from the original display and a coating of a fluororesin by processing. 2. The method according to claim 1, wherein the coating of fluororesin contains an amount of pigment which does not interfere with the visibility of the underlying display. 3. A method for producing a molded article having a coating of fluorine resin on the surface of a rolled metal sheet, and then subjecting this to plastic working to produce a molded article having the coating of fluorine resin on the surface. After forming a coating of fluorine-based resin, a predetermined original indication is given with a paint containing a colorant at a predetermined position on the surface determined based on the rolling direction of the metal plate, and then plastic working is applied to the original indication. A method for producing a molded article having a desired indication derived from it and a coating of a fluororesin. 4. The original display is applied by using a coating material containing a colorant, a fluorine-based resin, a solvent and a polymer substance soluble in the solvent, according to any one of claims (1) to (3). The method described. 5. The method according to claim 1, wherein the rolled metal plate is a circular plate. 6. The rolled metal plate is a manganese-aluminum alloy rolled plate, and the original indication is on a straight line passing through the center of the disc and parallel to the rolling direction or in the vicinity thereof and perpendicular to the rolling direction passing through the center of the disc. The method according to claim (5), wherein the method is performed on at least one position on or near the straight line. 7. A rolled metal plate, which is cut out from a long metal rolled plate and has an instruction portion for instructing a rolling direction on the periphery thereof, and a rolling direction of the metal plate determined based on the instruction portion is used. The method according to any one of claims (1) to (6), characterized in that the original display is applied to a predetermined position determined based on the reference. 8. The method according to claim 7, wherein the indicator is a protrusion provided on the peripheral edge. 9. The method according to any one of claims (1) to (8), wherein the plastic working is drawing.