US-12625072-B2 - Method for inspecting shaped product, and method for manufacturing shaped product

US12625072B2US 12625072 B2US12625072 B2US 12625072B2US-12625072-B2

Abstract

A method for inspecting a molded article, the method enabling non-destructive inspection of an internal condition of a molded article containing fluorine, and a method for producing a molded article including the inspection method. The method for inspecting a molded article includes a step (A1) of inspecting an internal condition of a molded article having a fluorine content of 30% by mass or more based on image data obtained by imaging the molded article by optical coherence tomography.

Inventors

Takahisa Aoyama
Hayato Tsuda
Yuuki Kuwajima

Assignees

DAIKIN INDUSTRIES, LTD.

Dates

Publication Date: 20260512
Application Date: 20210928
Priority Date: 20190329

Claims (10)

1 . A method for inspecting a molded article, comprising: a step (A1) of inspecting an internal condition of a molded article having a fluorine content of 30% by mass or more based on image data obtained by imaging the molded article by optical coherence tomography (OCT), wherein in the OCT imaging, light from a light source of an OCT device has an incident angle α of 5 to 10 degrees relative to the molded article, wherein the incident angle α is the angle formed by the incident direction of the light and a perpendicular to a surface of the molded article, and wherein the molded article has a single-layer structure.
2 . The inspection method according to claim 1 , further comprising a step (A2) of determining whether the molded article is a good product or not based on a result of the inspection in the step (A1).
3 . The inspection method according to claim 1 , wherein the molded article contains a fluorine-containing polymer.
4 . The inspection method according to claim 1 , wherein the molded article contains a melt-fabricable fluororesin.
5 . The inspection method according to claim 1 , wherein the molded article is an injection-molded article.
6 . The inspection method according to claim 1 , wherein the step (A1) is a step of inspecting cracking and delamination inside the molded article based on the image data.
7 . A method for producing a molded article comprising: a step (B1) of molding a material containing a fluorine atom to provide a plurality of molded articles each having a fluorine content of 30% by mass or more; a step (B2) of selecting at least one molded article from the plurality of molded articles and inspecting an internal condition of the selected molded article based on image data obtained by imaging the selected molded article by optical coherence tomography (OCT); and a step (B3) of sorting a good product from the plurality of molded articles based on a result of the inspection in the step (B2), wherein in the OCT imaging, light from a light source of an OCT device has an incident angle α of 5 to 10 degrees relative to the molded article, wherein the incident angle α is the angle formed by the incident direction of the light and a perpendicular to a surface of the molded article, and wherein the molded article has a single-layer structure.
8 . The method for producing a molded article according to claim 7 , wherein the step (B3) includes: a step (B3-1) of determining whether the molded article inspected in the step (B2) is a good product or not based on the result of the inspection in the step (B2); and a step (B3-2) of sorting a molded article determined as a good product in the step (B3-1) from the plurality of molded articles provided in the step (B1).
9 . A method for inspecting a molded article, comprising: a step (A1) of inspecting an internal condition of a molded article having a fluorine content of 30% by mass or more based on image data obtained by imaging the molded article by optical coherence tomography (OCT), wherein in the OCT imaging, a filter containing a crystalline polymer is provided between a light source of an OCT device and the molded article, wherein the crystalline polymer is at least one selected from the group consisting of a tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, and a tetrafluoroethylene/hexafluoropropylene copolymer.
10 . A method for producing a molded article comprising: a step (B1) of molding a material containing a fluorine atom to provide a plurality of molded articles each having a fluorine content of 30% by mass or more; a step (B2) of selecting at least one molded article from the plurality of molded articles and inspecting an internal condition of the selected molded article based on image data obtained by imaging the selected molded article by optical coherence tomography (OCT); and a step (B3) of sorting a good product from the plurality of molded articles based on a result of the inspection in the step (B2), wherein in the OCT imaging, a filter containing a crystalline polymer is provided between a light source of an OCT device and the molded article, wherein the crystalline polymer is at least one selected from the group consisting of a tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, and a tetrafluoroethylene/hexafluoropropylene copolymer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a Rule 53(b) Continuation of International Application No. PCT/JP2020/014112 filed Mar. 27, 2020, claiming priority based on Japanese Patent Application No. 2019-066862 filed Mar. 29, 2019, the respective disclosures of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The disclosure relates to methods for inspecting a molded article and methods for producing a molded article. BACKGROUND ART Fluororesin is excellent in properties such as heat resistance, abrasion resistance, and chemical resistance and is widely used, as one of representative engineering plastics, for products such as molded articles. Patent Literature 1 discloses a specific method for ultrasonically inspecting an object to be inspected made from a fluororesin. CITATION LIST Patent Literature Patent Literature 1: JP 2006-145559 A SUMMARY The disclosure relates to a method for inspecting a molded article, including a step (A1) of inspecting an internal condition of a molded article having a fluorine content of 30% by mass or more based on image data obtained by imaging the molded article by optical coherence tomography. Advantageous Effects The disclosure can provide a novel method for inspecting a molded article, the method enabling non-destructive inspection of an internal condition of a molded article containing fluorine, and a method for producing a molded article including the inspection method. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view of an example of an optical coherence tomography (OCT) device that may be used in the inspection method of the disclosure. FIG. 2 is an enlarged view of an OCT device that may be used in the inspection method of the disclosure, showing an example of an embodiment in which a sample is placed with an inclination. FIGS. 3(a)-3(d) are schematic views of examples of the shape of a molded article that may be used in the inspection method of the disclosure. FIG. 4 is a schematic view of an OCT device that may be used in the inspection method of the disclosure, showing an example of an embodiment in which a spacer is used to adjust the incident angle of light. FIG. 5 is a schematic view of arrangement of a sample in OCT in the examples. FIG. 6 is an OCT image obtained in Example 1. FIG. 7 is an OCT image obtained in Example 2. FIG. 8 is an OCT image obtained in Example 3. FIG. 9 is an OCT image obtained in Example 4. FIG. 10 is an OCT image obtained in Example 5. FIG. 11 is an OCT image obtained in Example 6. FIG. 12 is an OCT image obtained in Example 7. FIG. 13 is an OCT image obtained in Example 8. FIG. 14 is an OCT image obtained in Example 9. FIG. 15 is an OCT image obtained in Example 10. FIG. 16 is an OCT image obtained in Example 11. FIG. 17 is an OCT image obtained in Example 12. FIG. 18 is an OCT image obtained in Example 13. FIG. 19 is an OCT image obtained in Example 14. FIG. 20 is an OCT image obtained in Example 15. FIG. 21 is an OCT image obtained in Example 16. FIG. 22 is an OCT image obtained in Example 17. FIG. 23 is an OCT image obtained in Example 18. DESCRIPTION OF EMBODIMENTS The disclosure is described in detail below. The disclosure relates to a method for inspecting a molded article, including a step (A1) of inspecting an internal condition of a molded article having a fluorine content of 30% by mass or more based on image data obtained by imaging the molded article by the optical coherence tomography (OCT). The inspection method of the disclosure enables non-destructive inspection of an internal condition of a molded article, and thus enables inspection of all molded articles. This can therefore improve the reliability of the quality of molded articles. In addition, OCT imaging can be performed at high speed, and thus the above inspection method can be easily integrated into a production line of molded articles. This can therefore improve the reliability of the quality of molded articles without impairing the productivity in the production line. The molded article to be inspected in the step (A1) has a fluorine content of 30% by mass or more. The fluorine content is preferably 41% by mass or more, more preferably 59% by mass or more, while preferably 76% by mass or less. The fluorine content is determined by burning 10 mg of a sample by an oxygen flask combustion method, causing the decomposition gas to be absorbed by 20 ml of deionized water, and measuring the fluoride ion concentration in the absorption liquid by a fluorine selective electrode method. The molded article at least contains a material containing a fluorine atom, and is preferably a molded article of a polymer. The molded article preferably contains a fluorine-containing polymer. Examples of the fluorine-containing polymer include a polymer containing a fluorine atom, such as fluororesin and fluororubber. Preferred among these is fluororesin. The fluororesin preferably has a melting point of 100° C. to 360° C., more pref