JPWO2018143274A1 - Bonding method of resin molded products - Google Patents

Abstract

About the resin molded product which carried out the double molding of the thermoplastic crystalline resin composition, it connects so that the deformation | transformation of a resin molded product and the deformation | transformation of a hollow part may be suppressed small, and sufficient joint strength may be obtained. A joining method for joining a resin molded product made of a resin composition, wherein the irradiation surface 101a to be joined to the second molded product 102 is irradiated on the surface of the first molded product 101 with vacuum ultraviolet light, and the mold 30 The first molded product 101 is placed in the cavity 31, and the resin is injected into the cavity 31 so that the second molded product 102 is bonded and molded to the irradiation surface 101 a of the first molded product 101.

Description

  The present invention relates to a method for joining resin molded products in which double molding is performed after irradiation with vacuum ultraviolet light.

  Conventionally, resin molded products obtained by injection molding of thermoplastic resins have been used in various fields such as automobile parts, electrical / electronic equipment parts, and daily necessities. Such a resin molded product may be used as a composite molded product in which a plurality of resin molded products are joined to each other for the purpose of forming a three-dimensional hollow body and simplifying the process during component assembly.

  In order to join resin molded products, various joining techniques such as adhesives and heat welding are provided. However, the technology for joining resin molded products with adhesives can bond the resin molded products without deforming them, but generally it takes several hours to cure the adhesive, and the productivity is inferior. In a three-dimensional hollow body having a fine hollow portion such as a part, there is a problem that the adhesive leaks into the hollow portion and the groove is buried. The technique of thermally welding resin molded products can be joined in a few minutes, but burrs and thermal deformation may occur in the joined resin molded products.

  Moreover, the technique which processes and joins a resin molded product with vacuum ultraviolet light (VUV) is provided (refer patent document 1-4, nonpatent literature 1). According to this technique, it takes several minutes to several tens of minutes to join the resin molded product, but the deformation of the joined resin molded product is small. However, Patent Documents 1 and 2 and Non-Patent Document 1 assume that the resin molded product is made of an amorphous resin such as polymethyl methacrylate (PMMA) resin or cyclic olefin resin, and the bonding strength is 1 MPa or less. . Patent Documents 3 and 4 assume silicone adhesion.

  Furthermore, a double shot molding technology is used to produce a final resin molded product by first molding a resin molded product with the resin composition and then secondary molding the resin composition together with the resin molded product. Is provided. Resin molded products combining materials of different properties and materials of different colors are integrally molded by the double molding technology and used in various products. In the double molding, in order to secure the strength of the portion where the resin is joined by the secondary molding, there are cases where the portion to be joined is mechanically reinforced by providing an anchor such as a through hole or an undercut.

JP 2006-187730 A JP 2009-173894 A JP 2011-148104 A JP2013-147018A

Yoshinao Taniguchi and 4 others, “Jointing of cycloolefin polymers by photosurface activation: Evaluation of joint strength and application to microchannels”, Surface Technology, Society of Surface Technology, 2014, Vol. 65, No. 5, p. 36-41

  On the other hand, for molded products (particularly three-dimensional hollow bodies) that are subjected to large mechanical stress over a long period of time such as water pump parts, polybutylene terephthalate (PBT) resins and polyphenylene sulfide (PPS) resins having robust and stable properties are used. Such a thermoplastic crystalline resin can be used. In addition, when producing a composite molded product by joining resin molded products made of a resin composition, deformation of the resin molded product due to bonding is small, and a composite molded product having high bonding strength can be produced with high productivity. Is required.

  The above-mentioned technology for processing and bonding resin molded products with vacuum ultraviolet light has been able to suppress deformation of the resin molded products to a small extent, but it is possible to bond resin molded products made of amorphous resin and cure silicone adhesives. It was assumed and sufficient bonding strength could not be secured.

  On the other hand, when the resin composition is bonded by double molding, a large amount of heat is required to melt the resin of the primary molded product, and a sufficient welded state cannot be obtained, and the bonding strength may not be ensured. It was. In particular, when a crystalline thermoplastic resin composition is used for a primary molded product, a larger amount of heat is required to melt the crystallized resin. In addition, when reinforcing with an anchor to increase the bonding strength, it is natural that it is necessary to secure a space for providing such a reinforcing structure in the resin molded product. There was a problem that the degree of freedom decreased.

  The present invention is proposed in view of the above-described circumstances, and is a composite in which high bonding strength can be obtained for a resin molded product produced using a resin composition while suppressing deformation of the resin molded product. It is an object of the present invention to provide a joining method for producing a molded product with high productivity and high degree of freedom of shape.

  In order to solve the above-described problems, a method for joining resin molded products according to the present invention is a method for joining resin molded products made of a resin composition, and the second molded product on the surface of the first molded product Irradiate the region where bonding is planned with vacuum ultraviolet light, place the first molded product in a mold, and bond the second molded product to the region of the first molded product to be molded. Resin is injected into the mold.

  The resin composition may include a thermoplastic crystalline resin.

  According to the present invention, a composite molded product produced by double molding has a high bonding strength. In addition, it is possible to manufacture a composite molded product excellent in productivity and shape flexibility while suppressing deformation of the resin molded product, in particular, deformation of the hollow portion in the resin molded product constituting the three-dimensional hollow body.

It is a figure which shows roughly a series of processes of the joining method of a resin molded product. It is a photograph of a vacuum ultraviolet light irradiation apparatus. It is a photograph of a composite molded product. It is a graph which shows the relationship between the process conditions of the junction part of a 1st molded product, and joining strength.

  Hereinafter, embodiments of a method for joining resin molded products according to the present invention will be described in detail with reference to the drawings. In the present embodiment, a resin molded product is produced by double molding, and a thermoplastic resin composition is assumed as the resin composition. In the final molded product molded as a composite molded product with the first molded product by secondary molding, for the sake of convenience, a newly molded part will be referred to as a second molded product.

  A thermoplastic resin composition consists of a composition containing a thermoplastic crystalline resin and / or a thermoplastic amorphous resin. As the thermoplastic crystalline resin, for example, polyoxymethylene (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or a liquid crystal polymer may be used. As the thermoplastic amorphous resin, for example, polycarbonate (PC), cyclic polyolefin (COP), and cyclic polyolefin copolymer (COC) may be used. Thermoplastic crystalline resins are generally opaque, but may be translucent or transparent for resins with low crystallinity. In addition, the thermoplastic resin composition includes various fillers such as glass fibers, antioxidants and stabilizers, nucleating agents, lubricants, plasticizers, mold release agents, and colorants, which are generally added to the resin composition. Additives may be added.

  In the present embodiment, a first molded product produced by primary molding of the resin composition is placed in a mold. Then, the second molded product is made of the resin composition so as to be in contact with the first molded product by secondary molding, and these are bonded to each other. The first molded product and the second molded product include opposing surfaces joined to each other on the surface. In the secondary molding, the molten resin composition forming the second molded product flows along the opposing surface in the first molded product, so that these opposing surfaces have corresponding shapes. Yes. For example, if the opposing surface of the first molded product is substantially flat, the opposing surface of the second molded product is also substantially flat corresponding thereto. Further, the facing surface may be a surface having irregularities. For example, by providing an uneven anchor on the opposing surface of the first molded product, an uneven anchor corresponding to that is also provided on the opposing surface of the second molded product, so that the first molded body and the second molded body are more You may enable it to join firmly.

  FIG. 1 is a diagram schematically illustrating a series of steps of the present embodiment. As shown in FIG. 1A, a first molded product 101 is prepared, and a vacuum ultraviolet light (VUV) is irradiated onto the irradiation surface 101 a of the first molded product 101 using a vacuum ultraviolet light irradiation device 20. The first molded product 101 has an irradiation surface 101 a as an opposing surface to be joined to the second molded product 102.

  Here, vacuum ultraviolet light refers to light having a wavelength of 200 nm or less. In addition, vacuum ultraviolet light does not necessarily have to be irradiated in a vacuum, but ultraviolet light in the wavelength region is largely absorbed by air, so when irradiated in air, the distance that the vacuum ultraviolet light propagates Need to be shortened.

  In FIG. 1A, a vacuum ultraviolet light irradiation device 20 includes a light source 21 such as an Xe excimer lamp, and a reflecting plate 22 that reflects light emitted from the light source 21 toward an irradiation object. FIG. 2 is a photograph showing an example of a vacuum ultraviolet light irradiation apparatus. The vacuum ultraviolet light irradiation device shown in this photograph can irradiate ultraviolet light from the opening formed on the upper surface of the housing toward the upper part.

  As shown in FIG. 1A, the first molded product 101 has a substantially flat irradiation surface 101a. In the present embodiment, the vacuum ultraviolet light is irradiated from the vacuum ultraviolet light irradiation device 20 toward the irradiation surface 101a of the first molded product 101 for 2 minutes. By such irradiation treatment, a treatment layer 111 in which the properties of the resin composition have changed from the irradiation surface 101a to a predetermined depth is formed on the irradiation surface 101a of the first molded product 101.

In the present embodiment, the irradiation of the vacuum ultraviolet light onto the first molded product 101 can be appropriately set in consideration of the illuminance on the irradiated surface. For example, in the case of irradiation with vacuum ultraviolet light under the conditions of an irradiation distance of 10 mm and an illuminance of 6 mW / cm ² , the irradiation time may be 2 minutes, for example, but is not limited to 2 minutes and exceeds 0 minutes to 15 minutes. It may be the following time. Moreover, the time of 30 seconds or more and 10 minutes or less (for example, 1 minute or more and 7 minutes or less) may be sufficient. Because the irradiation surface 101a of the first molded product 101 is further deteriorated by the irradiation with the vacuum ultraviolet light, the bonding strength may be lowered. Therefore, the irradiation of the first molded product 101 with the vacuum ultraviolet light is performed within a predetermined time. It is preferable that

Here, the illuminance changes depending on the irradiation distance (distance from the light source to the irradiation surface), the output of the irradiation device, etc. Therefore, the irradiation condition of vacuum ultraviolet light is based on the amount of irradiation energy obtained from the product of illuminance and irradiation time. You may decide to. The irradiation energy amount may be at 0.1 J / cm ² or more 10J / cm ² or less, also 0.5 J / cm ² or more 6J / cm ² or less (e.g., 1 J / cm ² or more 3J / cm ² or less) It may be. In other words, when the illuminance is increased by increasing the output of the irradiation device and shortening the irradiation distance, the irradiation time can be shortened, so that processing in a shorter time becomes possible. However, in that case, there is a possibility that uneven processing due to the influence of unevenness or warpage of the joint surface is likely to occur.

  As shown in FIG. 1B, the first molded product 101 irradiated with vacuum ultraviolet light is placed in the cavity 31 of the mold 30. Here, FIG. 1B and FIG. 1C described later are cross-sectional views for explaining the inside of the mold 30. The irradiation surface 101 a that is scheduled to be bonded to the second molded product 102 in the first molded product 101 is exposed in the cavity 31 so as to be able to contact the resin composition injected into the cavity 31.

  Here, in order to ensure higher bonding strength, the operation of installing the first molded product 101 in the cavity 31 of the mold 30 is a step of irradiating the first molded product 101 with vacuum ultraviolet light (FIG. 1A ))), And as short as possible (preferably within 30 days, more preferably within 20 days, particularly preferably within 10 days).

  As shown in FIG. 1 (c), a fluid of a resin composition heated and pressurized through the injection hole 32 is injected into the cavity 31 of the mold 30, and the second molded product 102 is integrated with the first molded product 101. Secondary molding is performed so as to be molded. The second molded product 102 contacts and is joined to the irradiation surface 101a of the first molded product 101.

  As shown in FIG. 1 (d), when the resin composition injected into the cavity 31 of the mold 30 is solidified by secondary molding, the first molded product 101 and the second molded product that are finally molded integrally. 102 is removed from the mold. The first molded product 101 and the second molded product 102 are joined to the opposing surface of the second molded product 102 via a treatment layer 111 formed to a predetermined depth on the irradiation surface 101a of the first molded product 101. As a result, the first molded product 101 and the second molded product 102 are connected as a single body to form a single composite molded product (for example, a three-dimensional hollow body).

  In joining the first molded product 101 and the second molded product 102, the treatment layer 111 of the first molded product 101 activated by vacuum ultraviolet light is fused by the fluidized resin composition of the second molded product 102. It is what is done. Therefore, the connection between the first molded product 101 and the second molded product 102 is mechanically robust and chemically stable.

  In the present embodiment, the processing layer 111 is formed on the first molded product 101 by primary molding, and the second molded product 102 is connected to the first molded product 101 via the processing layer 111 by secondary molding. Therefore, since the joining itself is performed in the mold, the deformation due to the joining is small and no burr is generated.

  In the present embodiment, a thermoplastic resin composition containing a thermoplastic crystalline resin and / or a thermoplastic amorphous resin can be used as the resin composition. Thermoplastic crystalline resins include polyoxymethylene (POM), polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polyphenylene sulfide (PPS) resin, and liquid crystal polymer having robust and stable properties. A plastic crystalline resin can be used, and polycarbonate (PC), cyclic polyolefin (COP), and cyclic polyolefin copolymer (COC) can be used as the thermoplastic amorphous resin. In particular, the thermoplastic crystalline resin can be used for producing a resin molded product to which a large mechanical stress is applied over a long period of time.

  An example to which the above-described embodiment is applied will be described. FIG. 3 is a photograph showing a composite molded product. In the example of FIG. 3, a first molded product of 64 × 12.7 × 6.4 mm is manufactured from a black resin composition by primary molding, and a surface of 12.7 × 6.4 mm, which is one end surface, is formed. After being placed in a 127 × 12.7 × 6.4 mm mold cavity so as to be exposed, a white resin composition is injected into the remaining 63 × 12.7 × 6.4 mm space by secondary molding. Then, a second molded product joined to the end surface of the first molded product having a size of 12.7 × 6.4 mm was formed to produce a composite molded product. The composite molded article was prepared from a resin composition of non-reinforced PBT resin that does not contain an elastomer or a reactive compound (PBT resin Juranex (registered trademark) 2002, manufactured by Wintech Polymer Co., Ltd.).

FIG. 4 is a graph showing the relationship between the processing conditions of the bonded portion of the first molded product and the bonding strength. This graph shows the result of measuring the bonding strength using a tensile tester in accordance with ISO527-1, 2 using a composite molded product bonded by double molding according to the process described in FIG. In FIG. 4, as a comparative example, when the vacuum ultraviolet light (VUV) is not irradiated, when the ultraviolet light (UV) is irradiated instead of the vacuum ultraviolet light, the first molded product is bonded instead of the vacuum ultraviolet light irradiation. The case where uneven anchors were provided on the surface was shown. Note that irradiation with vacuum ultraviolet light (VUV) and ultraviolet light (UV) was performed for 7 minutes at an illuminance of 6 mW / cm ² .

  As can be seen from the measured values in FIG. 4, when the first molded product was subjected to a process of irradiating with vacuum ultraviolet light, a bonding strength sufficient for practical use was obtained. On the other hand, when the first molded product was not irradiated with vacuum ultraviolet light, the first molded product and the second molded product were not joined when irradiated with ultraviolet light instead of vacuum ultraviolet light. The bonding strength when irradiated with vacuum ultraviolet light is practically equivalent to the case where an anchor is provided on the bonding surface of the first molded product instead of irradiation with vacuum ultraviolet light, that is, when mechanical reinforcement is performed. Sufficient bonding strength was obtained.

101 First Molded Product 102 Second Molded Product 20 Vacuum Ultraviolet Light Irradiation Device 30 Mold 31 Cavity

Claims (2)

A joining method for joining resin molded products made of a resin composition,
Irradiate vacuum ultraviolet light to the area of the surface of the first molded product that is planned to be joined to the second molded product,
Install the first molded product in the mold,
Injecting resin into the mold so that a second molded product is joined and molded in the region of the first molded product.   The bonding method according to claim 1, wherein the resin composition includes a thermoplastic crystalline resin.