JP3476478B2 - Manufacturing method of synthetic resin products with identification mark - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin product, particularly a fluororesin product, having an identification mark.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION As a synthetic resin product such as a basket for a wafer used in manufacturing a semiconductor, a fluororesin, a polyolefin resin, a polyester resin, a polyetheretherketone resin or the like is used.

Among these synthetic resins, fluororesins such as polytetrafluoroethylene (hereinafter referred to as PTFE) are particularly heat resistant, weather resistant, chemical resistant, releasable, slippery, non-adhesive and mechanical. In terms of strength, etc., it has remarkably superior properties compared to other synthetic resins, so by utilizing this property, corrosion-resistant linings for pipelines, tanks, machinery, etc. that handle corrosive fluids or high-temperature fluids. Widely used as wood.

However, the fluororesin such as PTFE is characterized in that it is hard to get wet with water or oil and has a small adhesive energy. This is because the fluororesin has a large contact angle with water and a low intermolecular cohesive force, so
Since the intermolecular force at the polymer interface is low and the surface free energy is remarkably low, it is difficult to wet and adhere to a liquid or solid having a large intermolecular cohesive force.

Therefore, it is difficult to directly write characters or attach a label on the surface of a product molded using this fluororesin, such as a container,
There is a problem that it is not possible to attach an identification display of what the content is, or even if it is possible, it is difficult to retain the display for a long time.

The same applies to a wafer basket for accommodating and transporting a large number of flat silicon wafers for IC and LSI, for example. This wafer basket, which is molded from fluororesin, is widely used. However, this wafer basket is an identification mark that displays the manufacturing lot number, manufacturing date, etc. at the request of process control. The silicon wafers contained in the basket are individually managed.

However, since the wafer basket made of fluororesin has the above-mentioned characteristics such as water repellency, oil repellency, and non-adhesiveness, even if the identification mark is directly written on the wafer basket using a felt pen or the like. Alternatively, even if a sticker with an identification mark is attached, the identification mark is easily erased or the sticker is easily peeled off.

By the way, as one of the methods for adhering other members to such a fluororesin product, the fluororesin surface is treated with a solution of metallic sodium dissolved in liquid ammonia to chemically activate the surface. There is a way to make it.
It is also possible to use this method to put an identification mark on the surface of the fluororesin product.

However, this method has a problem in that the treatment liquid itself may cause environmental pollution and the handling thereof is dangerous, and an expensive device is required to prevent it. It was Further, the fluororesin surface treated by this method is discolored brown, not only the appearance is bad,
Since the treated surface is long, there is a problem that the adhesiveness is deteriorated when exposed to sunlight.

Further, the fluororesin surface is subjected to physical treatment such as plasma treatment or sputtering treatment,
Alternatively, a method of mechanically roughening the surface of the fluororesin has been proposed, but this method has problems such as time-consuming processing and cost increase.

Further, the applicant of the present invention cools a fluororesin product to a temperature above its melting point and then cools it to form 1000 or more / cm ² or more granular projections on the surface thereof, and to the surface thereof. The method of attaching identification is proposed. However, in this method, the fired fluororesin product must be fired again, and the adhesion of the coloring material such as ink is insufficient, so that a bar code is printed on the surface of the refired fluororesin product, for example. However, there was a possibility that a part of the thin line would have a thin part and the barcode could not be read.

When a synthetic resin product such as a fluororesin product having an identification mark such as a bar code is used in a heated state in an oxygen-containing atmosphere such as air, the identification mark such as the bar code is smeared in black. In some cases, the identification display cannot be read because of this.

Thus, there is a strong demand for the appearance of a synthetic resin product, particularly a fluororesin product manufacturing method, having an identification mark such that the identification mark does not bleed black even when used in a high temperature condition such as in air. It was rare.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, has a clear identification mark that is not easily erased, and can be easily read by various readers, and can be read in air. It is an object of the present invention to provide a method for producing a synthetic resin product, particularly a fluororesin product, having an identification mark such that the identification mark does not bleed black even when used at high temperatures.

[0015]

SUMMARY OF THE INVENTION A method of manufacturing an identification mark-attached synthetic resin product according to the present invention comprises a step of applying a coloring material to the surface of a synthetic resin molding to give a predetermined identification mark, and this identification mark. The synthetic resin molded body is heated to a temperature equal to or lower than the melting point of the synthetic resin to remove the thermally decomposable organic component contained in the coloring material, and the surface of the synthetic resin molded body on which the identification mark is attached. And a step of providing a substantially transparent synthetic resin film.

In the present invention, the synthetic resin molded product is preferably a fluororesin, particularly PTFE.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described more concretely based on the embodiments shown in the drawings. The identification resin-attached synthetic resin product manufactured by the present invention is formed by applying a synthetic resin molded body 1 and a coloring material provided on the surface of the synthetic resin molded body 1 as shown in FIG. Identification display 3,
It is composed of a substantially transparent synthetic resin film 5 provided on the identification display.

Examples of such a synthetic resin molded body 1 include fluororesins such as polytetrafluoroethylene, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, and polyether ether ketone (PEEK) resins. ,
The transparent synthetic resin film 5 may be the same resin as described above.

The case where the synthetic resin molding is polytetrafluoroethylene (PTFE) will be described in detail below. FIG. 2 is a cross-sectional view of an essential part showing a manufacturing process of a fluororesin product with an identification mark according to an embodiment of the present invention, FIG.
6 are perspective views of main parts showing an example of use of the fluororesin product.

A method of manufacturing a fluororesin product having an identification mark according to the present invention will be described. In this manufacturing method, first, a PTFE film 2 as a PTFE molded body on which identification is desired is prepared. Although the thickness of the PTFE film 2 is not particularly limited, it is preferably 50 to 500 μm, and particularly 1
It is preferably from 00 to 200 μm.

In order to manufacture this PTFE film 2, for example, an extrusion aid having a relatively high viscosity and excellent lubricity, such as white oil, is first added to PTFE powder.
Isopar E and Sumoyle P-55 (both are trade names) are added to preform a cylinder, and this cylindrical preform (billet) is put into the cylinder of an extruder and pressed by a ram to form a die. Extrude. This is called paste extrusion.

If an unsintered PTFE extruded product containing this extrusion aid is rolled into a film and then the extrusion aid is extracted and dried to remove it, unsintered PTFE is obtained.
E film 2 is obtained.

Unfired PTFE formed in this way
First, film 2 is heated to 180 ° C or higher and PTF
Heat treatment is performed at a temperature equal to or lower than the melting point of E. By this heat treatment, the tackiness of the unbaked PTFE film 2 is retained, and the adhesion when ink is applied later is improved, and at the same time, the surface layer of the unbaked PTFE film 2 is peeled off. There will be no. The steps from paste extrusion molding to heat treatment as described above may be performed for each step or may be performed as a series of operations.

The unsintered PTFE film 2
Can be referred to as a non-filled unbaked PTFE film 2 in the sense of being compared with a light-colored filler which will be described in detail later.

Next, an identification mark is attached to the surface of the heat-treated unsintered PTFE film 2. Examples of the means for attaching the identification display include an XY plotter, screen printing, gravure printing, a coating method, a spin coating method, and brush coating. In particular, in the present invention, a thermal transfer recording type printer, for example, a bar code printer. Is preferred.

The means for attaching the identification mark is unbaked PTFE.
As shown in FIG. 2 (B), the coloring material 4 is attached to the surface of the film 2 in an identification display shape. The identification display shape is
It suffices that the entire shape of the coloring material 4 viewed from the surface side (direction of arrow A) of the PTFE film 2 constitutes some sort of identification display. As the identification display shape, language, letters, numbers,
The shape is not limited to a picture, a bar code, etc., and may be any shape as long as it forms some kind of identification display. Since the adhesiveness of the unbaked PTFE film 2 is retained even by the heat treatment, the adhesiveness when ink is applied is improved and the surface layer of the unbaked PTFE film is not peeled off. A coloring material can be conveniently applied to the surface of the film 2, and the coloring material will not be easily erased. During the coating process, a recess may be provided on the surface of PTFE and the coloring material may be embedded in the recess. As a means for forming the concave portion on the surface of the film 2, for example, a mold body provided with a protrusion of some identification display shape may be stamped or imprinted on the surface of the PTFE film 2. The depth of the recess is not particularly limited, but is preferably 10 to 100 μm, particularly preferably 40 to 60.
μm. However, the depth of the recesses is reduced by the PTFE film 2.
It is preferable that the thickness does not exceed the thickness. This is to prevent the film 2 from breaking. As a concrete means for forming the above-mentioned concave portion, for example, in the step of stamping with a mold, ink or the like is applied to the surface of the mold and placed.
It is preferable to embed a coloring material such as ink in the recess at the same time when the recess is formed at the time of stamping. More specifically, stamping and coloring can be performed simultaneously with a commercially available typewriter or the like. With current typewriters, only letters and numbers can be stamped, but barcodes and the like may be stamped. The coloring material may be any material as long as it colors the surface of the PTFE 2, and is a concept including paints, inks, and the like.

As described above, the fluororesin molding (PTFE
After the coloring material is applied to the surface of the film) and given a predetermined identification mark, the PTFE molded body is heated to remove the thermally decomposable organic component contained in the coloring material. When such a heat treatment step is performed, organic components such as wax, resin component, and organic solvent contained in the coloring material are decomposed and removed, and even if the obtained fluororesin product is heated during use. , Will not be colored.

The above heat treatment is carried out at a temperature not higher than the melting point of the synthetic resin.
In the case of FE, it is desirable to carry out at a temperature of 200 ° C. or higher, preferably 250 ° C. or higher and lower than the melting point of PTFE. However, heat treatment may be performed at a temperature equal to or higher than the melting point of PTFE for a short time.

Next, a substantially transparent fluororesin film 6 is provided on at least the surface of the unsintered PTFE film 2 having the identification mark. The substantially transparent fluororesin film 6 has a thickness of at least 20 μm or more, preferably 0.3 to 3 mm, and the attachment thereof is made of PTF.
The entire E film 2 may be covered. The substantially transparent fluororesin film 6 may be substantially transparent to the extent that the identification mark by the coloring material 4 can be seen from the outside. The transparent fluororesin film 6 is preferably a film having excellent chemical resistance and excellent adhesion to the PTFE film 2, for example, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether. It is molded with a fluororesin such as PFA, FEP which is a copolymer of tetrafluoroethylene and hexafluoropropylene, or EPE which is a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether.

The lamination of the unsintered PTFE film 2 and the substantially transparent fluororesin film 6 is not less than the melting point of the transparent fluororesin film 6 and the PTFE.
When the heating is performed at a melting point of 2 or less, as shown in FIG. 2 (E), two films 6 are used so that the peripheral edges 6a of the films 2 are covered so as to cover the front and back surfaces of the PTFE film 2. It is preferable to perform it by heat fusion. The film 6 is made into PTFE at a temperature below the melting point of PTFE.
It is difficult to heat-bond the film 2 to the film 2, and the film 2 is sealed by the two films 6.

When the PTFE film 2 is laminated below the melting point, the PTFE film 2 remains unfired. Further, since the heat fusion is performed at a temperature equal to or lower than the melting point of PTFE, deterioration of the coloring material for identification display formed on the surface of the PTFE film is small.

Although the temperature for fusion bonding depends on the material of the transparent film 6, for example, the PFA film 6 is used.
In the case of using, the heating temperature is preferably 315 to 325 ° C., and the peripheral edges 6 a of the transparent fluororesin films 6 are well fused by the temperature in this range, and the PTFE film 2 is well sealed. After this fusion, rapid cooling or slow cooling may be performed, and since PTFE is not fired, there is no concern that the transparency of PTFE will increase due to the decrease in crystallinity. When the fluororesin film 6 is laminated on the upper and lower surfaces of the PTFE film 2 at a temperature equal to or higher than the melting point of PTFE, as shown in FIG. 2 (F), the surface of the PTFE film 2 having the identification mark and the PTFE film 2 The entire peripheral surface including the lower surface is heat-sealed with the fluororesin film 6 made of PFA or the like. By doing so, the fluororesin film such as PFA is fused to the upper and lower surfaces of the PTFE film, so that the rigidity of the entire product is improved.

In the present invention, the fluororesin molding may be manufactured as follows. In this manufacturing method, a PTFE film 2 having the same thickness as in the above manufacturing method is prepared, and the unsintered PTFE film 2 is heat-treated at a temperature of 180 ° C. or higher and a temperature not higher than the melting point of PTFE, and this heat treatment is performed. The identification mark is attached to the surface of the unsintered PTFE film 2 by the means as described above.

The PTFE molded product with this identification mark is heated to a temperature below the melting point of PTFE to remove the thermally decomposable organic component contained in the coloring material. Then, when the substantially transparent fluororesin film 6 is adhered, or before and after the adhesion, as shown in FIG.
At least one layer of fluororesin substrate 7 is laminated on the back surface of the. By providing this fluororesin substrate 7, the rigidity of the entire product is improved. This fluororesin substrate 7 is made of PTFE
The film 2 is made of the same or different fluororesin.

The shape of the fluororesin substrate 7 is not limited to the plate shape, but may be any other shape. At the same time as or before and after laminating the fluororesin substrate 7 on the back surface of the PTFE film 2, the unbaked P
On the surface side of the TFE film 2, the substantially transparent fluororesin film 6 as described above is laminated in an adhered state, and PT
Heat fusion is performed at the melting point of FE or higher. For example, when the PFA film 6 is closely attached to the PTFE film 2, the heating temperature is preferably 340 to 360 ° C.,
As a result, the transparent fluororesin film 6, the PTFE film 2 and the fluororesin substrate 7 are brought into close contact with each other.
In this case, the PTFE film 2 and the fluororesin substrate 7
If it is heat-fused via the fluororesin film 6 described above, the PTFE film 2 and the fluororesin substrate 7 can be more firmly fused.

After this close contact, they are rapidly cooled. This quenching is performed with cooling water or the like, and the quenching speed is 5 to 1
00 ° C./sec is preferable. According to such a quench,
The coloring material 4 is not deteriorated because it is exposed to a high temperature for a short time. Further, even if the crystallinity of the PTFE film 2 is lowered and the transparency is increased by the rapid cooling, since the fluororesin substrate 7 is adhered to the back surface of the PTFE film 2, the identification display can be made by various readers. It's not hard to read.

Further, in the present invention, the fluororesin product may be manufactured as follows. In this method, the unsintered PTFE film 2 filled with a light-colored filler is used.

In order to fill the PTFE film 2 with this light-colored filler, PTFE for forming a preform is formed.
The light color filler may be mixed with the powder. The light-colored filler may be any as long as it is filled in PTFE to make PTFE light-colored, and is used in a broad sense including pigments, and specifically, boron nitride, titanium oxide,
Alumina, zinc oxide, calcium fluoride, silicon nitride, etc. are exemplified. In the present invention, the bright color system
It means a wide range of light reflectance, and includes not only pure white but also colors close to white, such as milky white, cream or other colors. The filling amount of the filler varies depending on the kind of the filler, but in general, for PTFE,
0.1 to 30% by weight is preferable.

Also in this manufacturing method, an unsintered PTFE film 2 having the same thickness as that described above is prepared. However, unlike this manufacturing method, the PTFE film 2 contains a light-colored filler. This unbaked PTFE film 2 with bright color filler
Is heat-treated at a temperature of 180 ° C. or higher and not higher than the melting point of the PTFE film 2, and the heat-treated unbaked P is
An identification mark is attached to the surface of the TFE film 2 in the same manner as described above.

The means for attaching the identification mark is unbaked PT.
As shown in FIG. 2B, the dark coloring material 4 is adhered to the surface of the FE film 2 in an identification display shape. The dark coloring material is not limited to pure black, and P
The surface of TFE film 2 is colored in some way,
It is not particularly limited as long as it makes a difference in light and shade or a difference in shade from the color of the E film 2, and any material other than paint, ink, etc., which is different from the color of the surface of the PTFE film 2, may be used. That is, any material may be used as long as it has a reflectance different from that of the surface of the PTFE film 2. From the viewpoint of reading the identification display on the surface of the PTFE film 2 using a reader that reads information based on the difference in reflectance, it is not always necessary that the PTFE film 2 side is a light color system and the coloring material side is a dark color system. , And vice versa.

The PTFE molded product with this identification mark is heated to a temperature below the melting point of PTFE to remove the organic components contained in the coloring material. Next, as shown in FIG. 2 (E), the transparent film 6 is laminated on the front and back surfaces of the PTFE film 2, and their peripheral edges 6a are heat-sealed to each other. This fusion is performed by heating above the melting point of the transparent fluororesin film 6 and below the melting point of the PTFE 2.

This manufacturing method is the same as the manufacturing method described above, except that the PTFE film contains a light-colored filler.
Further, in the present invention, the fluororesin product may be manufactured as follows.

In this method, the unsintered PTFE film 2 is filled with the light-colored filler, and the PTF containing the unsintered light-colored filler having the same thickness as that of the above-mentioned embodiment.
The E film 2 is prepared, the unsintered PTFE film 2 is heat-treated at a temperature of 180 ° C. or higher and a temperature not higher than the melting point of PTFE, and the surface of the heat-treated unsintered PTFE film 2 is marked.

The PTFE molded product with this identification mark is heated to a temperature not higher than the melting point of PTFE to remove the organic components contained in the coloring material. Next, at the time of laminating the substantially transparent fluororesin film 6 on the surface side of the unsintered PTFE film 2 marked with at least the identification mark, heating and fusion are performed at a melting point of PTFE 2 or higher.

The reason why the melting point of PTFE2 is set to the above is that the fluororesin film 6 and PTF which are transparent at this temperature are used.
This is because the E film 2 will be fused and integrated. After the fusion bonding, the films 2 and 6 are rapidly cooled. This quenching is performed with cooling water or the like, and the quenching speed is 5
-100 ° C / sec is preferable. According to such quenching, the coloring material 4 is exposed to high temperature for a short time.
Does not deteriorate. Further, even if the crystallinity of the PTFE film 2 is lowered by the rapid cooling, since the film is filled with the light-colored filling material, the film does not become transparent and can be identified by various readers. The display does not become difficult to read.

An example of application of the fluororesin product 10 with such an identification mark is a case where it is used in a wafer basket 11 as shown in FIG. The wafer basket 11 has a basket body 12 that accommodates a large number of silicon wafers W for forming a semiconductor circuit in parallel. This basket body 1
2 is formed of, for example, a fluororesin because it needs to be a material having chemical resistance in order to sequentially subject the silicon wafer W to chemical treatment. A groove 13 for accommodating a large number of the silicon wafers W is formed inside the basket main body 12, and an end wall of the basket main body 12 has a mark plate M made of the fluororesin product 10 with the identification mark. Can be attached and removed freely.

On the mark plate M, an identification display such as a bar code is formed by the above-described manufacturing method of the present invention. The mark plate M is attached to the basket body 1
Since it is detachably attached to the end wall of No. 2, the protrusion T
a is formed, and the mounting hole o of the mark plate M is fitted into the protrusion Ta.

In the wafer basket 11 to which the mark plate M is attached in this way, it is possible to control the process of a large number of silicon wafers W accommodated inside the basket body 12. That is, necessary information for manufacturing the silicon wafer W, for example, the manufacturing lot number, the manufacturing date, and the like, can be obtained by reading the identification mark attached to the mark plate M by the bar code reading device. The information can be immediately known, which enables reliable process control.

As another means for removably attaching the mark plate M to the basket body 11, as shown in FIG. 4, a pair of L-shaped angle members 16, 16 are attached to the end wall of the basket body 12, Both angle members 16,1
A mark plate insertion groove 17 is formed by both inner side surfaces of the mark plate 6, and the mark plate M
May be inserted. Further, as shown in FIG. 5, a pair of mounting holes 18, 18 are formed in the end wall of the basket body 12, and a pin 19 projecting from the mark plate M side is fitted into the mounting holes 18, 18. Good. Further, as shown in FIG. 6, the elastic legs 2 are attached to the mark plate M.
0, 20 may be provided, and the elastic legs 20, 20 may sandwich the projection 21 of the basket body 12.

Further, in the above-mentioned embodiments, the PTFE film is used as the PTFE body, but the present invention is not limited to this, and the PTFE sheet or the other three-dimensional PTFE molded body is provided with an identification mark. It is also applicable when attached.

[0051]

As described above, according to the present invention, when the synthetic resin product is a fluororesin, a PTFE molded article having an identification mark such as a bar code is attached to the PTF.
Since it includes a step of heating to a temperature below the melting point of E to remove the organic components contained in the coloring material, even if the fluororesin product is used in a high temperature state such as in air, the identification display bleeds black. Never. Further, according to the present invention, since the unbaked fluororesin film heat-treated at a predetermined temperature is used, the coloring material can be conveniently applied to the surface of this film, and the coloring material is It will not disappear easily.

Furthermore, when a non-sintered PTFE film 2 filled with a light-colored filler is used, and a transparent fluororesin film is fused to this, and when this is rapidly cooled, the fluororesin film is rapidly cooled. Even if the crystallinity is lowered, the light-colored filler material in the film does not increase the transparency of the film, and various readers can easily read the identification mark on the film. Also,
Since it is rapidly cooled, the coloring material forming the identification mark formed on the PTFE film does not deteriorate.

Furthermore, when at least one fluororesin substrate is laminated on the back surface of the PTFE film, the rigidity of the entire product is improved. Moreover, since there is no step such as re-baking, the fluororesin product can be manufactured inexpensively and easily.

The present invention will be described below based on more specific examples, but the present invention is not limited to such examples.

[0055]

[Example] About 2 parts of PTFE fine powder (manufactured by DuPont Mitsui Fluorochemicals) with an extrusion aid (Isopar E)
After adding 0% by weight and mixing uniformly, add about 5 kgf / cm
After preforming in ² , the paste was extruded in an extruder and the extrusion aid was dried to obtain a 0.1 mm thick unsintered PTFE film. Then, this unfired PTF
The E film was heat-treated at 320 ° C. for about 2 hours.

Next, a bar code was attached to the surface of this heat-treated unsintered PTFE film by using a thermal ribbon D105B (manufactured by Ricoh Co., Ltd.). At this time, PT
A barcode was clearly printed on the surface of the FE film, and no surface peeling of the unbaked film was observed.

Next, the PTFE film with this identification mark was heat-treated at 320 ° C. for 12 hours. Next, the whole surface of the unsintered PTFE film on which the bar code was printed was covered with a PFA film having a thickness of 1 mm, and the temperature was raised to about 320 ° C. with a slight pressing force applied, followed by rapid cooling.

The fluororesin product thus obtained was allowed to stand in the air at 290 ° C. for 6 hours, then 220 ° C.
No discoloration was observed in the identification display portion even after being immersed in sulfuric acid for 6 hours.

As a result, there is little deterioration of the bar code due to the temperature rise, and a commercially available bar code reader (BL-made by Keyence Corp.
It was easy to read with the 900 series, operating distance 150 mm).

[0060]

[Reference Example] In Example 1, a PT with an identification mark
A fluororesin product was produced in the same manner as in Example 1 except that the FE film was not heat-treated at 320 ° C. for 12 hours.

When the obtained fluororesin product was left in the air at 290 ° C. for 6 hours and then immersed in sulfuric acid at 220 ° C. for 6 hours, a slight discoloration was observed in the identification display part.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part of a synthetic resin molded body with an identification mark.

FIG. 2 is a sectional view of an essential part showing a manufacturing process of a fluororesin product with an identification mark.

FIG. 3 is a main part perspective view showing an example of use of a fluororesin product with an identification mark.

FIG. 4 is a perspective view of an essential part showing an example of use of a fluororesin product with an identification mark.

FIG. 5 is a perspective view of an essential part showing an example of use of a fluororesin product with an identification mark.

FIG. 6 is a perspective view of a main part showing an example of use of a fluororesin product with an identification mark.

[Explanation of symbols]

2 ... PTFE film 4 ... Coloring material 6 ... Fluororesin film 7 ... Fluororesin substrate 10 ... Fluororesin products

Front page continuation (51) Int.Cl. ⁷ Identification code FI G09F 1/02 G09F 1/02 Z 23/00 23/00 Z // B29K 27:12 B29K 27:12 (72) Inventor Nobuyoshi Sasaki Tokyo 2-3 2-3 Uchisaiwaicho, Chiyoda-ku Hibiya International Building Kawasaki Steel Co., Ltd. Tokyo Headquarters (72) Inventor Akira Shimomura 2-3-2 Uchisaicho, Chiyoda-ku, Tokyo Hibiya International Building Kawasaki Steel Co., Ltd. Company Tokyo Headquarters In-house (56) Reference JP-A-3-143677 (JP, A) JP-A-3-193896 (JP, A) JP-A-56-104020 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) B05D 7/02 B05D 5/06 B29C 47/00 B29C 63/02 B29C 69/00 G09F 1/02 G09F 23/00 B29K 27:12

Claims (6)

(57) [Claims] 1. A step of applying a coloring material to the surface of a synthetic resin molded article to give a predetermined identification mark, and heating the synthetic resin molded article having the identification mark to a temperature not higher than the melting point of the synthetic resin. Then, an identification mark consisting of the step of removing the thermally decomposable organic component contained in the coloring material and the step of providing a substantially transparent synthetic resin film on the surface of the synthetic resin molded product with the identification mark. A method for producing a synthetic resin product marked with. 2. The method according to claim 1, wherein the synthetic resin molding is a fluororesin. 3. The method according to claim 1, wherein the synthetic resin molded body is polytetrafluoroethylene (PTFE). 4. The synthetic resin molded article is a non-sintered PTFE molded article obtained by heat-treating unsintered PTFE extruded in a paste form at a temperature of 180 ° C. or higher and a melting point of PTFE or lower. The method described. 5. The method according to claim 1, wherein the synthetic resin film is a fluororesin film. 6. The method according to claim 1, wherein the synthetic resin molding contains a light-colored filler.