JPS6153933B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for joining thermoplastic elastomer molded articles. More specifically, the present invention relates to a joining method and apparatus that can be effectively applied to thermoplastic elastomer molded products having irregularly shaped end surfaces. For example, molded products with complex irregular cross sections, such as automobile window seal gaskets, have conventionally been molded mainly as vulcanized products of diene rubber such as SBR. However, when manufacturing such vulcanized products using these rubbers, the process of kneading softeners, fillers, reinforcing agents, etc. with the diene rubber using a Banbury mixer, etc., and subsequent strict temperature control are necessary. Below, a roll processing step in which the vulcanizing agent is mixed with the rubber at a temperature that does not cause vulcanization when mixing the vulcanizing agent, but at a temperature that fluidizes the rubber so that the vulcanizing agent is sufficiently mixed. After
The complicated process involves first preparing an unvulcanized compounded rubber containing a uniform blend of vulcanizing agents, softeners, fillers, reinforcing agents, etc., molding this compounded rubber into a predetermined shape, and then heating and vulcanizing it. As a result, such a method is not only not easy to manufacture, but also has problems in that it cannot be cheap. By the way, recently, thermoplastic elastomers that exhibit properties similar to vulcanized rubber near room temperature, while melting and flowing at high temperatures and exhibit properties similar to thermoplastic resins, have been attracting attention. , to obtain a molded product only by normal molding and cooling, without requiring complicated processes such as a roll processing step and a vulcanization step, which are essential when manufacturing a vulcanized molded product from the rubber. It has the advantage of being able to Therefore, the present inventors attempted various cast molding methods to form molded products with complex irregular cross sections using thermoplastic elastomers having such favorable properties, but none of them yielded the desired shape. It was difficult to obtain a molded article with For this reason, the main parts of the desired molded product are molded by extrusion molding, etc.
By joining molded linear or non-linear segments of a predetermined length in a linear or non-linear manner, we succeeded in obtaining a molded product with a desired shape. Accordingly, the present invention relates to a method for joining thermoplastic elastomer molded products, in which the ends of thermoplastic elastomer molded products, preferably extrusion molded products, to be joined to each other are joined to each other. A molded article having the same end surface as the end surface of the product is preheated in a split mold that can be cast, preferably injection molded, in a state separated from each other, and then a thermoplastic elastomer is injected between the ends of the molded product in the split mold. This is done by cooling. The present invention also relates to a molded product joining device used for joining such thermoplastic elastomer molded products, and this molded product joining device allows at least one of the split molds to slide into contact with each other and It consists of a pair of split molds that can be separated, each split mold having a through hole drilled from its opposing contact surface to the other surface having the same cross-sectional area as the end of the molded product to be joined. A resin inlet for cast molding, preferably a resin inlet for injection molding, is provided on the upper part of the contact facing surface where the end faces of the through holes are in the same position, and the resin inlet is further fitted into the through hole of the separated mold. The device is equipped with a heater having an insertable heating section. The invention will now be explained with reference to the drawings. FIG. 1 of the drawings is a front view of one embodiment of a molded product joining apparatus according to the present invention, and FIG. 2 is a right side view thereof. FIG. 3 is a plan view a, a left side view b, and a front view c of the heater used for linear joining shown in FIGS. 1 and 2. FIG. 4 is a plan view a, a front view b, and a right side view c of a set of split molds used for non-linear joining. Figure 5 shows the fourth
They are a plan view a, a left side view b, and a front view c of the heater used in the split mold shown in the figure. In Figures 1 and 2, the upper fixing base 2 is attached to the column 1.
A lower fixed base 2' and a movable base 3 are respectively attached, and the movable base 3 is attached to the lower fixed base 2'.
By operating a hydraulic ram 4 installed above, it can move up and down using the support 1 as a guide. A fixed split mold 6 mounted on a fixed split mold mounting base 5 and a movable split mold 8 mounted on a movable split mold mounting base 7 are respectively attached to the movable base 3.
The split mold mounted on the movable platform is configured to be able to slide left and right on the slide rail 11 using the slide rail fixing plate 10 as a guide by the operation of the hydraulic cylinder 9, and by this sliding, it can move with the fixed split mold 6. The split mold 8 has mutually contacting opposing surfaces 12a and 12b.
contact or separate. The embodiments shown in FIGS. 1 to 3 show a linear joining method. The fixed split mold 6 and the movable split mold 8 each consist of an upper mold 6a or 8a and a lower mold 6b or 8b, and each upper mold and lower mold can be opened by a hinge 13a or 13b, During joining, the split molds 6 or 8 are closed by the fasteners 14a or 14b. Each split mold 6 or 8 is provided with a through hole 16a or 16b having the same plum-like cross section as the end surface of the extrusion molded product to be joined, from its contact facing surface 12a or 12b to its facing surface 15a or 15b. The end surfaces 17a and 17b of these through holes 16a and 16b are in contact with the opposing surface 12.
It is in the same position in a and 12b. When joining, first, the end surfaces of the thermoplastic elastomer extrusion molded products to be joined to each other are inserted up to the positions of lines 18a and 18b, respectively, and then the ends of these extrusion molded products, which are separated from each other, are preheated. . Preheating is performed by separating heating parts 22a and 22b of a heater 21 rotatably mounted on a heater mounting rod 20 that is slidably mounted on bearings 19a and 19b fixed to each split mold 6 and 8. This is done by fitting into the through holes 16a and 16b of each split mold. When the preheating is completed, the heater 21 is removed and returned to the position 21' outside the split mold, and the separated movable split mold 8 is slid into contact with the fixed split mold 6. Thereafter, a thermoplastic elastomer that is the same as or has an affinity for the extruded product is injected from a nozzle 24 into an injection molding material inlet 23 provided at the upper part of the contact facing surface 12, and is cooled. The embodiment shown in Figures 4-5 shows a set of split dies and heaters used in non-linear right angle joining. The mold halves 6' and 8' extend from their contacting opposing surfaces 12' to their adjacent side surfaces 15.
A through hole 16a' or 16b' having the same plum blossom-like cross section as the end face of the extrusion molded product to be joined is bored through a' or 15b'. When joining, each end face of the thermoplastic elastomer extrusion molded products to be joined to each other is connected to the line 18.
They are fitted to positions a' and 18b', and then preheating and injection injection of thermoplastic elastomer are performed in the same way as in the case of linear joining. However, the heating part 21' of the heater 21' used for preheating is
Since a' and 22b' are not on a straight line with each other, if the arm length is constant, the through holes 16a' and 1
6b', it is necessary to have a double structure consisting of a rod-shaped body 25 and a tubular body 26, and the length of the arm must be made variable by sliding between them. By such a joining method of the present invention, a joint is formed that exhibits a strength substantially equal to that of the molded products to be joined, and the appearance of the joint is also good. As a result, as long as the cross-sectional shape can be molded with a split mold, joints can be effectively formed not only with regular cross-sectional shapes but also with complicated irregular cross-sections, and with ring-shaped and other arbitrary shapes. Molded articles having any general shape can be obtained regardless of size. The thermoplastic elastomer to which this joining method is applied to the molded product is a blend of a polyolefin resin and a partially crosslinked product of ethylene/α-olefin copolymer rubber. things are shown. (i) Various polyolefin resins represented by homopolymers of ethylene or propylene or copolymers with small amounts of other polymerizable monomers, and ethylene and α-olefins having 3 to 14 carbon atoms. A thermoplastic composition consisting of a blend of a partially crosslinked ethylene/α-olefin copolymer rubber, which is an original copolymer rubber or a terpolymer rubber obtained by further copolymerizing various polyene compounds with the original copolymer rubber (e.g. , Japanese Patent Publication No. 53-21021 and Japanese Patent Application Laid-Open No. 55-71738) (ii) A blend obtained by dynamically heat-treating a blend of a polyolefin resin and an ethylene/α-olefin copolymer rubber. Thermoplastic compositions (for example, see Japanese Patent Publication No. 53-34210, Japanese Patent Publication No. 53-149240, and Japanese Patent Publication No. 53-149241) (iii) A combination of polyolefin resin and ethylene/α-olefin copolymer rubber A thermoplastic composition obtained by dynamically heat-treating a blend and further blending a polyolefin resin (for example, Japanese Patent Application Laid-open No. 145857/1985 and No. 54
(Refer to Publication No. 16554) (iv) Peroxide crosslinked polyolefin resins typified by homopolymers of ethylene or copolymers with small amounts of other polymerizable monomers, homopolymers of propylene or small amounts of copolymers with other polymerizable monomers; Heat obtained by dynamically heat-treating a blend of a peroxide non-crosslinked polyolefin resin, typically a copolymer with other polymerizable monomers, and an ethylene/α-olefin copolymer rubber. Plastic compositions (see, for example, JP-A-55-71739) The ethylene/α-olefin copolymer rubber used to prepare these various thermoplastic elastomers has a ratio of ethylene and α-olefin of 50/50 to 50/50.
When copolymerized at a molar ratio of 90/10, preferably 55/45 to 85/15, and a polyene component is further copolymerized, the iodine value of the copolymer is about 4.
-75, preferably about 8-40. It is desirable that these ethylene/α-olefin copolymers have a Mooney viscosity of ML ₁₊₄ (100° C.), generally about 10 to 150, preferably about 30 to 100. Partial crosslinking of these ethylene/α-olefin copolymer rubbers is generally achieved by dynamic heat treatment using about 0.1 to 2 parts by weight of organic peroxide per 100 parts by weight of the copolymer rubber containing polyolefin resin. It will be done. In this case, the polyolefin resin constituting the thermoplastic elastomer, preferably a partially crosslinked product of polypropylene and ethylene/α-olefin copolymer rubber, is mixed in various weight ratios depending on the properties of the molded product formed from them. It is used by blending it so that In addition, these thermoplastic elastomers may contain peroxide non-crosslinked hydrocarbon rubber-like substances such as polyisobutylene and butyl rubber, mineral oil-based softeners, fillers, colorants, etc., as necessary. It can also be blended. A thermoplastic elastomer that is the same as or has an affinity for the extruded products to be joined is used to form the joint, and the joint is performed by cast molding including injection molding. In the case of non-linear joints, it is possible to form not only joints with a certain angle but also joints with a certain degree of radius, making it possible to obtain molded products with a wide variety of overall shapes. make it possible. Next, the effects of the present invention will be explained with reference to Examples. Examples 1 to 4, Comparative Examples 1 to 4 25 parts by weight of crystalline polypropylene, 3 parts by weight of ethylene/propylene/5-ethylidene-2-norbornene
Original copolymer rubber [ethylene/propylene (molar ratio) = 79/21, iodine value 12, Mooney viscosity ML ₁₊₄
A thermoplastic elastomer made of a blend of 54 parts by weight of a partially cross-linked product (82% insoluble content when extracted in cyclohexanone at 23°C for 48 hours) and 21 parts by weight of paraffinic process oil.
A plate-shaped body having a width of 70 mm and a thickness of 3 mm was continuously extruded and cut into a length of 100 mm to obtain a test piece. This plate-shaped specimen was linearly joined as shown in FIGS. 1 to 3. As the injection molding material, a thermoplastic elastomer having the same composition as the plate-shaped body molding material was used. The results obtained are shown in the table below, and the following can be said from the results. In other words, when preheating is not performed, the appearance is good when the injection pressure is relatively low, but the retention rate of stress at break is extremely reduced to around a few percent, whereas when the injection pressure is increased, the stress retention rate is reduced to around 30%. Although the rate will be restored, the appearance will be damaged. For this reason, it is completely impossible to obtain a joint that maintains an excellent stress retention rate without impairing its appearance. On the other hand, the method of the present invention, which performs preheating, shows a high stress retention rate of 90% or more even at a relatively low injection pressure, and can form a joint with an excellent appearance. In addition, when the ends to be joined are preheated to 200℃ for 20 seconds and crimped according to the conventional butt welding method, the stress at break of the joint is 104Kg/cm ² (retention rate 95
%) was obtained, but the burr condition was evaluated as ×.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a front view of one embodiment of a molded product joining apparatus according to the present invention, and FIG. 2 is a right side view thereof. Figure 3 is a plan view a and a left side view b of the heater used for linear joining shown in Figures 1 and 2.
and a front view c. Figure 4 is a plan view a and a front view b of a set of split molds used for non-linear joining.
and right side view c. Figure 5 shows a top view a and a left side view b of the heater used in the split mold in Figure 4.
and a front view c. In these drawings, numeral 6 indicates a fixed split mold;
8 is a movable split mold, 12 is their contact facing surface, 1
Reference numeral 6 designates a through hole, 21 a heater, 22 a heating portion thereof, 23 a resin inlet for injection molding, and 24 a nozzle.

Claims (1)

[Scope of Claims] 1. Preheating the ends of thermoplastic elastomer molded products to be joined to each other in a separated mold in a split mold capable of casting a molded product having the same end face as the end face of each molded product. After that, a thermoplastic elastomer is injected between the ends of the molded product in the split mold, and the thermoplastic elastomer is cooled. 2. A method for joining thermoplastic elastomer molded products according to claim 1, wherein molded products having irregularly shaped end surfaces are joined. 3. The method for joining thermoplastic elastomer molded products according to claim 1 or 2, wherein the thermoplastic elastomer molded products to be joined are extrusion molded products. 4. The method for joining thermoplastic elastomer molded products according to claim 1, wherein a split mold that can be injection molded is used as the split mold that can be cast. 5 Claim 1 in which linear joining is performed
A method for joining thermoplastic elastomer molded products as described in . 6. A method for joining thermoplastic elastomer molded products according to claim 1, wherein non-linear joining is performed. 7 Consists of a pair of split molds that can be brought into contact with and separated from each other by sliding at least one of the split molds, and each split mold is connected to the end surface of the molded product to be joined from its contact facing surface to the other surface. A through-hole having the same cross-sectional area as the through-hole is bored, and a cast molding material inlet is provided at the upper part of the contact facing surface where the end surfaces of these through-holes are in the same position. A molded product joining device equipped with a heater having a heating part that can be inserted into a through hole of a split mold. 8. The extrusion molded product joining device according to claim 7, wherein a through hole having an irregular cross section is formed in the split die. 9. The molded product joining device according to claim 7, wherein an injection molding material inlet is provided as the injection molding material inlet. 10. The molded product joining device according to claim 7, wherein the heater is rotatably attached to the heater mounting rod. 11. The molded product joining device according to claim 7, wherein the through-hole of one split mold and the through-hole of the other split mold are bored in a linear positional relationship. 12. The molded product joining device according to claim 7, wherein the through-hole of one split mold and the through-hole of the other split mold are formed in a non-linear positional relationship.