Weather strip

Abstract

To provide a method for manufacturing a weather strip having a seal part in which a base layer and a skin layer are laminated that can release foaming gas generated from the base layer to an outside via the skin layer during a manufacturing process of the weather strip.SOLUTION: A weather strip 10 includes a seal part 11 that seals between a vehicle body panel 2 and a rear door 4. The seal part 11 includes a base layer 13 and a skin layer 14 that covers an outer surface of the base layer 13. The base layer 13 is made of a rubber foam. The skin layer 14 is made of a resin foam and has open cells 14a inside. A method for manufacturing the weather strip includes: an extrusion molding step in which a base layer composition and a skin layer composition are simultaneously co-extruded; and a heating step in which a weather strip precursor extruded in the extrusion molding step is heated. In the extrusion molding step, a foaming agent in the skin layer composition is foamed, and in the heating step, the foaming agent in the base layer composition is foamed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a weatherstrip having a sealing portion that seals when sandwiched between the periphery of a vehicle body opening in a vehicle body panel and a door body that can close the vehicle body opening, and in particular to a weatherstrip in which a skin layer is laminated on the sealing portion, and a method for manufacturing the same. [Background technology]

[0002] Examples of such weatherstrips include Patent Documents 1 and 2 listed below. In Patent Document 1, the seal portion (seal portion 40) has an outer surface of a base layer (elastic portion 42) made of a foamed rubber material, which is covered with a skin layer (protective layer 44) made of a non-foamed rubber material. In Patent Document 1, the base layer and the skin layer are laminated together in an extrusion molding process in which a base layer composition and a skin layer composition are simultaneously co-extruded, and the base layer is foamed and vulcanized in a heating process in which the weatherstrip precursor extruded in the extrusion molding process is heated. During this process, the foaming agent in the base layer foams, which can cause unevenness on the outer surface of the base layer. However, these unevenness are covered by the skin layer, making the outer surface of the seal portion smooth, and the presence of the skin layer also improves abrasion resistance.

[0003] In Patent Document 2, a skin layer (micro-foam sponge rubber coating 34) made of micro-foam sponge rubber with a specific gravity of 0.9 to 1.1 is laminated on the surface of a base layer (sponge rubber layer 33) of a seal part (hollow seal part 32) made of sponge rubber. Patent Document 2 aims to provide a weatherstrip that is abrasion resistant and has excellent appearance at corners by laminating a skin layer to prevent wrinkles from forming in the seal part due to uneven deformation when the weatherstrip is attached to the corner part of a vehicle body panel, thereby preventing the appearance from being deteriorated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-104134 [Patent Document 2] Japanese Patent Application Publication No. 9-2072 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the skin layer is made of a non-foaming rubber material, which allows the skin layer to suppress the foaming gas generated during foaming of the base layer. However, since the seal portion is pressed against the vehicle body panel or door body, it is necessary to avoid adhesion to these mating materials, but rubber materials have poor adhesion resistance. Therefore, to provide adhesion resistance to the seal portion, the skin layer is sometimes molded from a resin material. Resin materials soften due to heat during the extrusion molding process and have lower viscosity than rubber materials, so they cannot suppress the foaming gas generated when the base layer foams. Furthermore, with non-foaming resin materials, the foaming gas has no escape route from the base layer, and the foaming gas ends up accumulating at the interface between the base layer and the skin layer. This can deteriorate the appearance and sealing performance of the skin layer and, ultimately, the seal portion.

[0006] The skin layer in Patent Document 2 is made of micro-foamed sponge rubber, but because it is micro-foamed and has a relatively high specific gravity of 0.9 to 1.1, the internal cells are thought to be closed cells rather than open cells where adjacent cells are connected to each other. Therefore, even in Patent Document 2, the foaming gas generated from the base layer cannot escape (discharge) to the outside through the skin layer.

[0007] The present invention solves the above-mentioned problems and aims to provide a method for manufacturing a weatherstrip having a sealing portion formed by laminating a base layer and a skin layer made of a resin material, in which foaming gas generated from the base layer can be released to the outside through the skin layer, and a weatherstrip with a good appearance obtained by this method. [Means for solving the problem]

[0008] To achieve this, the present invention employs the following means. (1) A method for manufacturing a long weatherstrip having a sealing portion that seals a vehicle body opening in a state where the sealing portion is sandwiched between a periphery of the vehicle body opening in a vehicle body panel and a door body that can close the vehicle body opening, The sealing portion has a base layer that forms the shape of the sealing portion and a skin layer that covers at least a part of the outer surface of the base layer, the base layer is made of a rubber foam obtained by foaming a base layer composition containing a foaming agent in a rubber material, the surface layer is made of a resin foam obtained by foaming a surface layer composition containing a foaming agent in a resin material; an extrusion molding step of simultaneously co-extruding the base layer composition and the skin layer composition; a heating step of heating the weatherstrip precursor extruded by the extrusion molding step, In the extrusion molding step, a foaming agent in the composition for a skin layer is foamed, In the heating step, a foaming agent in the base layer composition is foamed. (2) The method for producing a weatherstrip according to (1), wherein the composition for the surface layer contains 0.1 to 3 parts by weight of the foaming agent per 100 parts by weight of the resin material. (3) The rubber material in the base layer composition is EPDM; The method for producing a weatherstrip according to (1), wherein the resin material in the composition for the surface layer is an olefin-based thermoplastic elastomer. (4) The method for producing a weatherstrip according to (1), wherein the composition for the surface layer contains silicone oil. (5) The method for producing a weatherstrip according to (1), wherein the foaming agent in the skin layer composition is a chemical foaming agent. (6) A long weather strip having a sealing portion that seals while being sandwiched between a periphery of a vehicle body opening of a vehicle body panel and a door body that can close the vehicle body opening, The sealing portion has a base layer that forms the shape of the sealing portion and a skin layer that covers at least a part of the outer surface of the base layer, the base layer is made of a rubber foam obtained by foaming a rubber material, the surface layer is made of a resin foam obtained by foaming a resin material, The weatherstrip, wherein the cells in the surface layer are interconnected cells in which adjacent cells are connected to each other. (7) The weatherstrip according to (6), wherein the surface layer contains silicone oil.

[0009] In this specification, the expression "XXX to XXX" indicating a numerical range means "XX or more and XX or less" unless otherwise specified. [Effects of the Invention]

[0010] According to measures (1) and (6), the skin layer is formed from a resin material, which has better adhesion resistance than a skin layer formed from a rubber material, preventing the seal from adhering to a mating material such as a door body. Furthermore, if the skin layer is foamed first and the cells in the skin layer are open, a communication path is formed inside the skin layer that runs from the back to the front. In other words, a communication path is formed inside the skin layer that runs from the base layer to the outside. This allows the foaming gas generated from the base layer to escape (exhaust) to the outside through the skin layer, preventing foaming gas from accumulating between the base layer and the skin layer, resulting in a weatherstrip with a good appearance. If both the base layer and the skin layer are foamed, the weatherstrip can be made lighter.

[0011] According to the measures (2) and (5), the cells in the skin layer can be easily made to be open cells. According to the measure (3), it is possible to ensure good bonding strength between the base layer and the skin layer while ensuring elasticity in the base layer.

[0012] By adding any additive to the surface layer, it is possible to impart any desired function or improve physical properties, etc. For example, by means of (4) and (7), the sticking resistance of the surface layer is further improved, and the slipperiness is also improved, so that wear even when the seal portions rub against each other can be prevented. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic side view of a vehicle. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. [Figure 5] FIG. 2 is a schematic diagram showing a manufacturing process. [Figure 6] 1 is a photograph showing the appearance of Example 1. [Figure 7] 1 is a photograph showing the appearance of Example 2. [Figure 8] 1 is a photograph of the appearance of Comparative Example 1. [Figure 9] 1 is a photograph of the appearance of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] The weatherstrip of the present invention is a component that is sandwiched between the periphery of a body opening in a body panel and a door body that can close the body opening to seal the space between the two, and is a long component that is extruded to have a substantially uniform shape along its entire length.

[0015] Such weatherstrips are used, for example, on the periphery of vehicle body openings such as the front door opening, rear door opening, trunk opening, back door opening, and roof opening. Specifically, they can be used as center pillar moldings, door seals, door opening seals, back door seals, hood seals, etc. Weatherstrips are attached in an annular shape to flanges that form the peripheries of these vehicle body openings, or to body panels, front doors, rear doors, etc., so as to surround part or the entire periphery of the vehicle body opening.

[0016] An embodiment in which the present invention is applied to a quarter window molding will be described below as an example of the present invention. As shown in Fig. 1, a vehicle 1 such as an automobile has, in a part of a body panel 2, body openings for a front door 3 and a rear door 4, as well as a body opening for a quarter window 5. The body openings for the front door 3 and the rear door 4 can be opened and closed by the front door 3 and the rear door 4, respectively. The quarter window 5 is fitted and fixed in the body opening for the quarter window 5 via a quarter window molding 6 arranged around the entire periphery of the body opening. Reference numeral 7 denotes a decorative garnish.

[0017] Furthermore, a weatherstrip 10 of this embodiment is disposed along the rear door 4 side of the quarter window molding 6. As shown in Figures 2 and 3, this weatherstrip 10 is integrally equipped with a sealing portion 11 and an attachment portion 12. The attachment portion 12 is a plate-like portion shaped to fit the shape of the gap between the quarter window molding 6 and the body panel 2 (in this embodiment, the cross section is L-shaped), and the weatherstrip 10 is attached to a portion of the periphery of the vehicle body opening in the body panel 2 by sandwiching this attachment portion 12 between the quarter window molding 6 and the body panel 2.

[0018] The seal portion 11 is a hollow cylindrical portion that allows for easy elastic deformation, and is located closer to the vehicle body opening for the rear door 4 than the quarter window molding 6. As a result, when the rear door 4 is closed, the seal portion 11 is pressed by the rear door 4, and the gap between the vehicle body panel 2 and the rear door 4 is sealed by the weatherstrip 10.

[0019] The seal portion 11 has a base layer 13 that forms the basic shape, and a skin layer 14 that covers at least a portion of the outer surface of the base layer 13. Note that the mounting portion 12 is formed from the same material as the base layer 13, and therefore, hereinafter, the description of the material of the base layer 13 also applies to the description of the material of the mounting portion 12. In this embodiment, the skin layer 14 is laminated from at least the area that abuts the rear door 4 and the garnish 7 to the area that abuts the vehicle body panel 2. The seal portion 11 is composed of only two layers, the base layer 13 and the skin layer 14, and no other layers are laminated. As such, the elastic deformation of the seal portion 11 is not unnecessarily hindered, and the pressing force (compressive load with which the seal portion 11 is pressed) when the rear door 4 is closed is designed to be as small as possible.

[0020] As shown in FIG. 4, the base layer 13 is made of a rubber foam with multiple bubbles 13a inside, formed by foaming a base layer composition containing a rubber material and a foaming agent. The rubber material that forms the base layer 13 is not particularly limited, and any rubber material previously known for this type of weather strip can be used without particular restriction. Examples include various rubber materials such as EPDM (ethylene propylene diene copolymer), EPM (ethylene propylene copolymer), chloroprene rubber, SBR (styrene-butadiene rubber), and NBR (acrylonitrile-butadiene rubber). Among these, EPDM is preferred due to its excellent weather resistance and heat resistance. Polyolefin resins such as polyethylene and polypropylene may also be added to these materials. For example, a polymer alloy containing polyethylene can be used in addition to EPDM.

[0021] The foaming agent added to the base layer composition is not particularly limited, and any foaming agent conventionally known in this type of weatherstrip can be used without any particular limitation. For example, microcapsules or thermally decomposable chemical foaming agents can be used. Examples of chemical foaming agents include ADCA (azo compound), DPT (nitroso compound), OBSH (hydrazine compound), sodium bicarbonate, and composites of these. Among these, OBSH-based chemical foaming agents are preferred, as they have a relatively low thermal decomposition temperature (approximately 160°C). Two or more foaming agents may be added.

[0022] By making the base layer 13, including the mounting portion 12, from a rubber foam, the overall weight of the weatherstrip 10 is reduced, but the base layer 13 must also ensure a certain level of shape retention strength. Therefore, the specific gravity of the base layer 13 is preferably 0.45 to 0.9, and more preferably 0.5 to 0.8. If the specific gravity of the base layer 13 is less than 0.45, shape retention strength may not be ensured. On the other hand, if it exceeds 0.9, the overall weight of the weatherstrip 10 becomes too heavy. Furthermore, the hardness of the base layer 13, particularly the mounting portion 12, is preferably 30 to 65 degrees on the Shore A scale. If the Shore A scale hardness is within this range, the holding force and durability of the mounting portion 12 are good.

[0023] The content of the foaming agent in the base layer composition is preferably 1.0 to 3.5 parts by weight, more preferably 2.0 to 3.0 parts by weight, per 100 parts by weight of the rubber material. By ensuring that the content of the foaming agent in the base layer composition is within this range, the specific gravity of the molded base layer 13 can be set within the above range. On the other hand, if the content of the foaming agent in the base layer composition is less than 1.0 part by weight, the weight of the base layer 13 will be insufficient. If the content of the foaming agent in the base layer composition is more than 3.5 parts by weight, the internal porosity will be too high, which may result in a decrease in elasticity and shape retention strength. The foaming agent in the base layer composition may be added as a masterbatch containing the foaming agent rather than being added directly to the rubber material; however, the above content of the foaming agent refers to the amount of the foaming agent only.

[0024] The cells 13a formed inside the base layer 13 may be interconnected cells, but it is preferable that a large proportion of the cells are independent (disconnected) cells. If the cells 13a in the base layer 13 are interconnected cells, the amount of foaming gas generated during foaming of the base layer composition that flows toward the skin layer 14 can be minimized. The thickness of the base layer 13 may be within the range conventionally used for this type of weatherstrip, approximately 0.5 to 3 mm.

[0025] The skin layer 14 is laminated to provide the seal portion 11 with resistance to adhesion to the mating members (the rear door 4 and the garnish 7 in this embodiment), and also to cover the foamed irregularities of the base layer 13 to provide a smooth surface and a good appearance. For this reason, the skin layer 14 is made of a resin foam having a plurality of bubbles 14a inside, which is formed by foaming a skin layer composition containing a foaming agent into a resin material as a base material.

[0026] 4, the cells 14a in the skin layer 14 are interconnected, with adjacent cells communicating with each other, forming interconnected channels within the skin layer 14 that connect the back surface (the base layer 13 side) to the front surface (the outside).

[0027] The thickness of the skin layer 14 is preferably 5 μm to 1 mm, and more preferably 10 μm to 0.3 mm. The thinner the thickness of the skin layer 14, the lower the pressing force (compression load pressing against the seal portion 11) when closing the rear door 4 and the lighter the weight. However, if the thickness is less than 5 μm, the skin layer is too thin and may be affected by the foaming unevenness of the base layer 13, reducing the surface smoothness and making it difficult to form the skin layer. On the other hand, if the thickness exceeds 1 mm, the compressive load pressing against the seal portion 11 may be higher than necessary, or it may be difficult to form communication paths inside the skin layer 14, making it difficult to discharge the foaming gas from the base layer 13.

[0028] The higher the hardness of the skin layer 14, the better the sticking resistance, but if it is too high, the compressive load pressing the seal portion 11 increases. Therefore, the hardness of the skin layer 14 is preferably HDA30 to 50 in terms of durometer hardness (type A) specified in JIS K 7215.

[0029] The specific gravity of the skin layer 14 is preferably as low as possible, preferably 0.3 to 0.8, and more preferably 0.5 to 0.7. If the specific gravity of the skin layer 14 is less than 0.3, the expansion ratio (porosity) of the skin layer 14 will be too high, resulting in foam irregularities on the surface of the skin layer 14. On the other hand, if the specific gravity exceeds 0.8, it may be difficult for the foaming gas from the base layer 13 to escape to the outside through the skin layer 14.

[0030] The resin material that is the base material of the skin layer 14 can be an olefin-based or styrene-based thermoplastic resin or thermoplastic elastomer. Among these, when EPDM is used as the base material of the base layer 13, an olefin-based thermoplastic elastomer is preferably used as the base material of the skin layer 14. If an olefin-based thermoplastic elastomer is used for the skin layer 14 while the base layer 13 is made of EPDM, the EPDM and the olefin-based thermoplastic elastomer are chemically bonded by the heat during extrusion molding, thereby increasing the adhesive strength between the base layer 13 and the skin layer 14 and preventing peeling of the skin layer 14 from the base layer 13. Specific examples of olefin-based thermoplastic elastomers include those containing 10 to 50 wt % of an olefin-based thermoplastic resin such as polypropylene or polyethylene and 20 to 50 wt % of a rubber-based material such as EPDM or SEBS.

[0031] The foaming agent added to the skin layer composition is preferably a chemical foaming agent that, based on the principle of bubble formation, tends to form open cells (14a). Examples of chemical foaming agents that can be used include ADCA (azo compound), DPT (nitroso compound), OBSH (hydrazine compound), sodium bicarbonate, and composites of these. Among these, sodium bicarbonate chemical foaming agents are preferred, as they generate relatively little foaming gas. When microcapsules are used as foaming agents, bubbles (14a) are formed between the capsules and the resin material as the microcapsules expand and contract. The foaming agents added to the skin layer composition and the base layer composition may be different or the same.

[0032] The content of the foaming agent in the skin layer composition is 0.1 to 3 parts by weight per 100 parts by weight of the resin material. When the content of the foaming agent in the skin layer composition is within this range, the cells 14a become open cells. On the other hand, if the content of the foaming agent in the skin layer composition is less than 0.1 part by weight, the number of cells 14a formed is small, making it difficult for the foaming gas from the base layer 13 to escape to the outside through the skin layer 14. On the other hand, if the content of the foaming agent in the skin layer composition is more than 3 parts by weight, the porosity becomes too high, resulting in foam irregularities on the surface of the skin layer 14.

[0033] Other additives can be added to the skin layer composition as needed. For example, adding 1 to 5 parts by weight of a lubricant per 100 parts by weight of the resin material can further improve the sticking resistance of the skin layer 14. Silicone oil, which is easily mixed into the skin layer composition, is preferred as the lubricant, but fluorine oil, spherical urethane filler, fatty acid amide, ultra-high molecular weight polyethylene resin, etc. can also be used. Using a thermoplastic elastomer foam for the skin layer 14 can also improve sticking resistance and slipperiness.

[0034] <Manufacturing method> The weatherstrip 10 of this embodiment is manufactured by extrusion molding. FIG. 5 schematically shows the manufacturing process for the weatherstrip 10. First, a base layer composition and a skin layer composition are extruded into a predetermined shape using an extruder 19. The extruder 19 is composed of an extruder 20 for the base layer composition, an extruder 21 for the skin layer composition, and a mold die 22 having a predetermined shaped nozzle 22a therein, and the extruders 20 and 21 are each connected to the mold die 22. The base layer composition and the skin layer composition are then simultaneously supplied to the mold die 22 from the extruders 20 and 21, respectively, to co-extrude the base layer 13 and the skin layer 14 (extrusion molding process). As a result, a series of weatherstrip precursors is extruded from the extruder 19, with the base layer 13 and the skin layer 14 already laminated together and the cross-sectional shape of the weatherstrip 10 continuing in the longitudinal direction.

[0035] Here, for example, if the base layer 13 is extruded and then the skin layer 14, which has been manufactured in a separate process, is later attached, there is a risk that the position of the skin layer 14 may shift relative to the base layer 13 or that the skin layer 14 may peel off from the base layer 13. In contrast, in this embodiment, the base layer 13 and the skin layer 14 are co-extruded in a laminated state, so that the skin layer 14 can be accurately laminated in a predetermined position without misalignment, and the adhesion between the base layer 13 and the skin layer 14 can also be improved.

[0036] The die 22a in the mold die 22 is set at a temperature near the passage through which the base layer composition extruded from the extruder 20 passes, at which the rubber material in the base layer composition softens but does not vulcanize, and at which the foaming agent does not foam. Meanwhile, the heater is set at a higher temperature near the passage through which the surface layer composition extruded from the extruder 21 passes, at which the resin material softens and the foaming agent foams. As a result, during the extrusion molding process, the weatherstrip precursor is extruded from the extruder 19, with the foaming agent in the skin layer 14 foamed but the foaming agent in the base layer 13 not foamed. The foaming agent contained in the base layer composition foams as the weatherstrip precursor is extruded from the extruder 19 and released to the outside. At this time, the cells 14a in the skin layer 14 are open.

[0037] Next, the weatherstrip precursor is fed into the heating tank 23, where it is heated sequentially (heating step). The heating tank 23 is a long, tunnel-shaped heating oven with a total length ranging from several meters to several tens of meters. The heating method in this heating tank 23 may be, for example, hot air heating using combustion gas or the like, microwave heating, or both.

[0038] The heating tank 23 is set at a temperature at which the foaming agent foams as the base layer 13 vulcanizes. Therefore, as the weatherstrip precursor passes through the heating tank 23, the foaming agent in the base layer 13 foams, generating foaming gas from the base layer 13. At this time, in the sealed portion 11, the foaming gas generated from the inner peripheral portion of the base layer 13 flows into the hollow space in the sealed portion 11, while the foaming gas generated from the outer peripheral portion flows toward the skin layer 14. However, since the skin layer 14 has open cells 14a that serve as communication paths connecting the base layer 13 to the outside, the foaming gas from the base layer 13 can be discharged to the outside through these open cells 14a. Meanwhile, the foaming gas accumulated in the hollow space in the sealed portion 11 can be discharged to the outside by piercing the sealed portion 11 with a needle at predetermined intervals in the longitudinal direction to form holes that penetrate the base layer 13 and the skin layer 14 in the thickness direction, or by opening the longitudinal end portions in a subsequent cutting process. Since the entire mounting portion 12 is exposed to the outside, the foaming gas generated from the mounting portion 12 is released to the outside without accumulating. By going through this heating process, the vulcanization and foaming of the base layer 13 and the mounting portion 12 are completed, and the weatherstrip precursor becomes a continuous weatherstrip 10.

[0039] The weatherstrip 10 that has undergone the heating process is then fed into a cooling tank 24, where the base layer 13 is cooled and solidified, and the skin layer 14 is hardened, thereby fixing the shape. A water tank may be typically used as the cooling tank 24. Next, the weatherstrip 10 is fed into a drainer 25 to remove moisture, and then taken up by a take-up machine 26. Finally, the continuous weatherstrip 10 is cut to a predetermined length by a cutter 27, thereby completing the product.

[0040] Although a typical embodiment of the present invention has been described above, the present invention is not limited to this, and in particular, the shapes of the sealing portion 11 and the mounting portion 12, i.e., the overall shape of the weatherstrip 10, may be modified in various ways depending on the location of application. [Example]

[0041] Examples and comparative examples in which the present invention was evaluated and tested are described below. In the examples and comparative examples, simulated weather strips consisting of only a hollow seal portion were produced for the purpose of evaluation testing. The formulations of the compositions used in the examples and comparative examples and the physical properties of the skin layers are shown in Table 1. The physical properties of the skin layers were measured by producing only the skin layer by independent extrusion. [Table 1]

[0042] The materials used in Table 1 are as follows: Rubber material: EPDM Base layer foaming agent: OBSH-based chemical foaming agent ("Neoslen" manufactured by Eiwa Chemical Industry Co., Ltd.) Resin material: Olefin-based thermoplastic elastomer (Milastomer, manufactured by Mitsui Chemicals, Inc.) Foaming agent for the surface layer: Sodium bicarbonate-based chemical foaming agent ("Polythren" manufactured by Eiwa Chemical Industry Co., Ltd.)

[0043] Each example and comparative example was extrusion molded under the following conditions. The base layer composition was fed from an extruder set at 50°C, and the skin layer composition was fed from an extruder set at 200°C, each into the same extruder. The co-extrusion expanded the blowing agent in the skin layer composition, which was then fed into a heating bath set at 200°C to vulcanize and expand the blowing agent in the base layer composition. The resulting mixture was then cooled, drained, and cut to obtain simulated weatherstrips for each example and comparative example. The appearance of each example and comparative example was then visually evaluated. Photographs of the resulting appearances are shown in Figures 6 to 9.

[0044] 6 and 7, the surfaces of the skin layers were smooth and had good appearances in Examples 1 and 2. This indicates that the cells in the skin layers in Examples 1 and 2 were open cells, and the foaming gas from the base layer was discharged to the outside through the open cells.

[0045] In contrast, as shown in FIG. 8, in Comparative Example 1, the foaming gas remained at the interface between the base layer and the skin layer. This is because no open cells were formed inside the skin layer, and the foaming gas generated from the base layer had no escape route. The skin layer in FIG. 8 is not colored to make the foaming gas easier to observe. Furthermore, as shown in FIG. 9, in Comparative Example 2, foam irregularities were formed on the surface of the skin layer, resulting in a poor appearance. This was due to the foaming agent content being too high in the skin layer composition. [Explanation of symbols]

[0046] 1 vehicle 2 Body panels 3. Front Door 4 rear doors 5 Quarter Window 6 Quarter window molding 7 Garnish 10 Weatherstrip 11 Seal part 12 Mounting part 13 Base layer 13a Bubbles 14 Epidermal layer 14a Bubbles 19 Extrusion molding machine 20·21 Extruder 22 Metal Dies 22a nozzle 23 Heating tank 24 Cooling tank 25 Drainer 26 Removal machine 27 Cutting machine

Claims

1. A method for manufacturing a long weatherstrip having a seal portion that seals a vehicle body opening in a state where the seal portion is sandwiched between a periphery of the vehicle body opening of a vehicle body panel and a door body that can close the vehicle body opening, The sealing portion has a base layer that forms the shape of the sealing portion and a skin layer that covers at least a part of the outer surface of the base layer, the base layer is made of a rubber foam obtained by foaming a base layer composition containing a foaming agent in a rubber material, the surface layer is made of a resin foam obtained by foaming a surface layer composition containing a foaming agent in a resin material; an extrusion molding step of simultaneously co-extruding the base layer composition and the skin layer composition; a heating step of heating the weatherstrip precursor extruded by the extrusion molding step, In the extrusion molding step, a foaming agent in the composition for a skin layer is foamed, In the heating step, a foaming agent in the base layer composition is foamed.

2. 2. The method for producing a weatherstrip according to claim 1, wherein the composition for the surface skin layer contains 0.1 to 3 parts by weight of the foaming agent per 100 parts by weight of the resin material.

3. The rubber material in the base layer composition is EPDM, The method for producing a weatherstrip according to claim 1, wherein the resin material in the composition for the surface layer is an olefin-based thermoplastic elastomer.

4. The method for producing a weatherstrip according to claim 1 , wherein the composition for the surface skin layer contains silicone oil.

5. The method for producing a weatherstrip according to claim 1, wherein the foaming agent in the skin layer composition is a chemical foaming agent.

6. A long weather strip having a sealing portion that seals while being sandwiched between a periphery of a vehicle body opening of a vehicle body panel and a door body that can close the vehicle body opening, The sealing portion has a base layer that forms the shape of the sealing portion and a skin layer that covers at least a part of the outer surface of the base layer, the base layer is made of a rubber foam obtained by foaming a rubber material, the surface layer is made of a resin foam obtained by foaming a resin material, The weatherstrip, wherein the cells in the surface layer are interconnected cells in which adjacent cells are connected to each other.

7. The weatherstrip of claim 6 , wherein the skin layer contains silicone oil.

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