Adhesive sheet for weather strip, weather strip, and method for manufacturing weather strip

Abstract

An adhesive sheet for the weatherstripping disclosed herein is a composition comprising at least EPDM, a crosslinking agent, and carbon black, and is tested using the JIS-K6271-1:2015 double-ring electrode method based on a 2 mm thick test sheet, having a thickness of 1.0 × 10⁻⁶. 6 Volume resistivity above Ω·cm. When the composition is placed in a mold, it reaches 100 kgf / cm. 2 The molding composition is pressed at 50°C for 60 seconds to prepare a molded part with a thickness change rate of less than 100%, which is expressed by the following formula (1): Thickness change rate = ((thickness of the molded part after releasing the pressure for 30 minutes - mold thickness) / mold thickness) × 100%.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive sheet for a weather strip, a weather strip, and a manufacturing method of a weather strip. More specifically, the present application relates to an adhesive sheet for bonding opposite end portions of a weather strip material to each other, a weather strip using the adhesive sheet, and a method of manufacturing the weather strip.

[0002] This international application is based on priority of Japanese Patent Application No. 2020-086087 filed on May 15, 2020, the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] Generally, in a vehicle such as an automobile, in order to seal a gap that can occur between a peripheral edge of an opening portion of a body panel and an opening and closing member attached to the body panel so as to be able to open and close, a weather strip is provided between the peripheral edge of the opening portion and the opening and closing member. Examples of the weather strip include a door weather strip (also referred to as a door seal, a door opening trim, or the like) provided between a door opening portion of a body panel and a door.

[0004] As a manufacturing method of such a weather strip, for example, Patent Literature 1 discloses a manufacturing method including the steps of facing a pair of end portions of a weather strip material to each other at a predetermined interval, and placing an adhesive sheet between the opposite end portions; and vulcanizing the adhesive sheet while pressing the weather strip material and the adhesive sheet against each other, and vulcanizing and bonding a main body portion formed of the weather strip material at a bonding portion formed by the adhesive sheet.

[0005] BIBLIOGRAPHIC REFERENCES

[0006] PATENT LITERATURE

[0007] Patent Literature 1: JP 2004-130552 A SUMMARY

[0008] The adhesive sheet is manufactured by, for example, press molding a composition containing a non-crosslinked rubber material and a crosslinking agent. For example, the adhesive sheet can contain a filler component for reinforcement purposes. When the adhesive sheet contains an electrically conductive filler component such as carbon black, the bonding portion has electrical conductivity. Here, when the electrical conductivity of the bonding portion is high, electrochemical corrosion (galvanic corrosion, rusting) occurs in the body panel through the bonding portion. Therefore, the mixing ratio of the electrically conductive filler component is considered to be reduced so as to reduce the electrical conductivity of the bonding portion.

[0009] However, according to the present inventors' studies, when the mixing ratio of the conductive filler component is simply reduced, the mixing ratio of the rubber material is relatively increased. Thus, when the pressure is released after press molding, the size of the adhesive sheet in the thickness direction can increase by an amount of elastic reduction of the size in the length direction. When the end portions of the weather strip material are adhered to each other by using the adhesive sheet having a large size in the thickness direction, the width of the adhesive portion increases. As a result, when the weather strip is installed to a vehicle, the appearance deteriorates, leading to a problem of deteriorated appearance quality.

[0010] The present application has been made to solve the above problems, and aims to provide an adhesive sheet for a weather strip, which can obtain a weather strip having a good appearance and excellent rust resistance of a body panel. Another object of the present application is to provide a weather strip using the adhesive sheet and a manufacturing method of the weather strip.

[0011] The technology disclosed herein provides an adhesive sheet for a weather strip, which is configured to adhere opposite end portions of a weather strip material to each other. The adhesive sheet is a composition containing at least EPDM, a crosslinking agent, and carbon black. The adhesive sheet has a volume resistivity of 1.0 x 10 6 Ω·cm or more based on the double ring electrode method of JIS-K6271-1:2015 of a test piece having a thickness of 2 mm. When the composition is placed in a mold and press molded at 100 Kgf / cm 2 and 50°C for 60 seconds to produce a molded piece, the molded piece has a thickness change rate of 100% or less, which is represented by Equation (1), and the Equation (1): thickness change rate = ((thickness of the molded piece after the pressure is released for 30 minutes - mold thickness) / mold thickness) x 100%.

[0012] According to such a configuration, it is possible to prevent the size of the adhesive sheet after press molding from increasing in the thickness direction. By adhering the end portions of the weather strip material to each other using the adhesive sheet whose size in the thickness direction is prevented from increasing, it is possible to obtain a weather strip in which the adhesive portion is unobtrusive and has a good appearance. Furthermore, according to such a configuration, it is possible to reduce the electrical conductivity of the adhesive portion. Thus, when the weather strip is installed to a vehicle, it is possible to prevent the body panel from rusting through the joint portion.

[0013] In a preferred aspect of the adhesive sheet disclosed herein, when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 19% by volume or less. According to such a configuration, by defining the mixing ratio of the carbon black in terms of volume ratio and setting the mixing ratio within the above range, it is possible to appropriately obtain a weather strip having a good appearance and excellent rust resistance of a body panel.

[0014] In another preferred aspect of the adhesive sheet disclosed herein, when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 16% by volume or less. According to such a configuration, by defining the mixing ratio of the carbon black in terms of volume ratio and setting the mixing ratio within the above range, rusting of the vehicle body panel can be prevented at a high level.

[0015] Further, the technology disclosed herein provides a weather strip including a main body portion having end portions and an adhesive portion that adheres the opposite end portions of the main body portion to each other.

[0016] In a preferred aspect of the weather strip disclosed herein, the adhesive portion is formed from a crosslinked product of any one of the adhesive sheets disclosed herein. According to such a configuration, a weather strip having excellent appearance quality and rust resistance of the vehicle body panel can be suitably obtained.

[0017] In a preferred aspect of the weather strip disclosed herein, the adhesive portion is formed from a crosslinked product of the adhesive sheet, and the adhesive sheet satisfies all of the following conditions: the composition contains at least EPDM, a crosslinking agent, and carbon black; when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 19% by volume or less; and the volume resistivity is 1.0 x 10 6 Ω·cm or more based on the double ring electrode method of JIS-K6271-1:2015 for a test piece having a thickness of 2 mm. According to such a configuration, a weather strip having excellent appearance quality and rust resistance of the vehicle body panel can be suitably obtained.

[0018] In another preferred aspect of the weather strip disclosed herein, the adhesive sheet has a thickness of 1.0 mm or less. According to such a configuration, the adhesive portion is not conspicuous, and the appearance quality of the weather strip can be further improved.

[0019] Further, the technology disclosed herein provides a method of manufacturing a weather strip including a main body portion having end portions and an adhesive portion that adheres the opposite end portions of the main body portion to each other, the method including: preparing a weather strip material for forming the main body portion and an adhesive sheet for forming the adhesive portion; and crosslinking the adhesive sheet by placing the adhesive sheet between the opposite end portions of the weather strip material. The adhesive sheet satisfies all of the following conditions: the composition contains at least EPDM, a crosslinking agent, and carbon black, the volume resistivity is 1.0 x 10 6 Ω·cm or more based on the double ring electrode method of JIS-K6271-1:2015 for a test piece having a thickness of 2 mm, when the composition is placed in a mold and heated at 100 Kgf / cm 2and when a molded piece is prepared by press molding the composition at 50°C for 60 seconds, the molded piece has a thickness change rate of 100% or less, the thickness change rate is represented by formula (1), and the formula (1): thickness change rate = ((thickness of the molded piece after the press is released for 30 minutes - mold thickness) / mold thickness) x 100%.

[0020] According to such a configuration, the adhesive portion can be formed between the body portions by cross-linking and bonding the adhesive sheet. Thus, the body portions and the adhesive portion can be firmly bonded to each other. In addition, the weather strip having excellent appearance quality and rust resistance of the body panel can be appropriately manufactured.

[0021] In a preferred aspect of the method of manufacturing the weather strip disclosed herein, the preparing includes manufacturing the adhesive sheet by press molding the composition by charging the composition into a press mold. According to such a configuration, the adhesive portion can be efficiently formed, and the productivity of the weather strip can be improved.

[0022] In another preferred aspect of the method of manufacturing the weather strip disclosed herein, the preparing includes using the press mold having a thickness of 0.5 mm or more when the mold is closed. According to such a configuration, good demolding property can be obtained after press molding. As a result, the weather strip can be stably manufactured, and the moldability and workability can be improved.

[0023] In another preferred aspect of the method of manufacturing the weather strip disclosed herein, the preparing includes manufacturing the adhesive sheet having a thickness of 1.0 mm or less. According to such a configuration, the weather strip having a more inconspicuous adhesive portion and particularly excellent appearance quality can be manufactured. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a front view of a weather strip according to the embodiments disclosed herein.

[0025] Figure 2 is a partial perspective view obtained by partially cutting off Figure 1

[0026] Figures 3A to 3D is a cross-sectional view showing an example of a manufacturing method of an adhesive sheet. DETAILED DESCRIPTION

[0027] ​Hereinafter, a preferred embodiment of the technology disclosed herein will be described. Matters other than matters specifically mentioned in this specification and matters necessary for implementing the technology can be understood as design choices of one skilled in the art based on the prior art. The technology can be implemented based on matters disclosed in this specification and the drawings and technical knowledge generally known in the art. In this specification, the expression "A to B" indicating a range includes, in addition to the meaning of A or more and B or less, the meanings of "preferably greater than A" and "preferably less than B".

[0028] <<Weather strip>>

[0029] Figure 1 is a front view of a weather strip 10 according to an embodiment of the technology. The weather strip 10 is attached to a periphery (an attached portion) of a rear door of a vehicle body panel, and seals a gap between a rear door opening portion and the rear door. As a result, it is possible to prevent rain, dust, noise, and the like from entering from the outside, and to improve the comfort of the vehicle. Here, the weather strip 10 has a ring shape (annular shape). The weather strip 10 includes a main body portion 20 having a pair of end portions 20a, and an adhesive portion 30 that adheres the opposite end portions 20a of the main body portion 20 to each other. Although one main body portion 20 and one adhesive portion 30 are provided here, two or more main body portions 20 and / or two or more adhesive portions 30 can be provided. The main body portion 20 includes, for example, a first main body portion and a second main body portion, and can include a pair of end portions of the first main body portion, a pair of end portions of the second main body portion, and the adhesive portion 30 that adheres the end portions of the first main body portion and the end portions of the second main body portion.

[0030] Figure 2 is a partial perspective view obtained by partially cutting the weather strip 10. The main body portion 20 is made of a weather strip material described later. The main body portion 20 is generally molded integrally and continuously by a press molding method. The main body portion 20 preferably has flexibility. The pair of end portions 20a of the main body portion 20 are substantially the same in shape, and substantially the same in cross-sectional area (allowing for manufacturing errors). Here, the main body portion 20 includes an attached portion 22 having a substantially U-shaped cross section and a hollow sealing portion 24.

[0031] The attached portion 22 is a portion for fixing the weather strip 10 to the vehicle body panel. The attached portion 22 is attached to the attached portion of the vehicle body panel. Here, the attached portion 22 is attached to a flange (not shown) provided along the opening edge of the rear door. The attached portion 22 includes a core metal 22a bent into a substantially U shape and a cover portion 22b covering the core metal 22a. The core metal 22a is embedded inside the cover portion 22b by insert molding. A plurality of retaining lips 23 Figure 2Four holding lips 23) are provided to the inner wall surface of the attachment portion 22. Each holding lip 23 extends toward the inside of the substantially U-shaped attachment portion 22. The plurality of holding lips 23 are arranged to face each other to be formed in pairs on the vehicle inner side and the vehicle outer side. The holding lips 23 sandwich the attached portion (flange) of the body panel from both the vehicle inner side and the vehicle outer side, thereby holding the attached portion.

[0032] The sealing portion 24 is a portion that seals the gap between the rear door opening portion and the rear door when the rear door is closed. The sealing portion 24 generally has higher flexibility than the attachment portion 22. The sealing portion 24 is configured to be elastically deformable. In a case where the rear door comes into contact with the sealing portion 24 when the rear door is closed, the sealing portion 24 is elastically deformed. Thus, the gap between the rear door opening portion and the rear door is sealed by the sealing portion 24. The sealing portion is not limited to Figure 2 the hollow shape shown, and can have, for example, a lip shape.

[0033] The adhesive portion 30 is interposed between the pair of end portions 20a of the main body portion 20. The adhesive portion 30 is a portion that serves as a joint of the main body portion 20. The adhesive portion 30 is formed of a crosslinked product of the adhesive sheet 3 (see Figures 3A to 3D ) described later. The adhesive portion 30 can have flexibility. The adhesive portion 30 is made of a material that has high compatibility (i.e., easily mixes) with the weather strip material. The adhesive portion 30 contains a crosslinked product of ethylene propylene diene rubber (EPDM) and carbon black. The adhesive portion 30 can contain the crosslinked product of EPDM as a first component (a component having the highest mixing ratio in terms of mass ratio, the same applies hereinafter), or can contain the crosslinked product of EPDM as a main component (a component accounting for 50% by volume or more of the total amount of the adhesive portion 30, the same applies hereinafter).

[0034] <Manufacturing method of weather strip>

[0035] The weather strip 10 can be manufactured by placing the adhesive sheet 3 (see Figures 3A to 3D ) between opposite end portions of the weather strip material and adhering the end portions of the weather strip material to each other through the adhesive sheet 3. The weather strip 10 can be manufactured by, for example, a manufacturing method including the following preparation step and vulcanization and adhesion step. The vulcanization and adhesion step is an example of a crosslinking step. Other steps can be included at any stage. Hereinafter, these steps will be described.

[0036] In the preparation step, the weather strip material and the adhesive sheet 3 (see Figures 3A to 3D). The weather strip material is used to form the main body portion 20 of the weather strip 10. The weather strip material can be the same as the material used for such applications in the prior art, and the material, properties, shape, etc. thereof are not particularly limited. The weather strip material can be made of rubber such as EPDM or chloroprene rubber. The weather strip material can be in a state where vulcanization is completed. The weather strip material can include a portion that forms the attachment portion 22 and a portion that forms the hollow seal portion 24. The material and properties of the weather strip material can be different between the portion that forms the attachment portion 22 and the portion that forms the seal portion 24.

[0037] The adhesive sheet 3 (see Figures 3A to 3D ) is used to form the adhesive portion 30 of the weather strip 10. The adhesive sheet 3 is used to adhere the opposite end portions of the weather strip material to each other. The thickness t (see Figures 3A to 3D ) of the adhesive sheet 3 can be about 5.0 mm or less, preferably 3.0 mm or less, more preferably 2.0 mm or less, particularly preferably 1.0 mm or less, and further preferably 0.9 mm or less. Thus, it is possible to manufacture the weather strip 10 in which the adhesive portion 30 is less conspicuous and the appearance quality is particularly excellent. The thickness t of the adhesive sheet 3 can be about 0.1 mm or more, for example, 0.3 mm or more or 0.5 mm or more.

[0038] The adhesive sheet 3 is a composition containing uncrosslinked ethylene-propylene-diene rubber (EPDM), a crosslinking agent, and carbon black as main components. Here, the adhesive sheet 3 is a composition containing unvulcanized EPDM, a vulcanizing agent, and carbon black. The adhesive sheet 3 can contain EPDM as a first component, or can contain EPDM as a main component. The adhesive sheet 3 will be described in detail later.

[0039] The adhesive sheet 3 can be manufactured by a method known in the prior art, such as molding, press molding, roll molding, calender molding, etc. In a preferred embodiment, for example, the adhesive sheet 3 can be manufactured as follows.

[0040] Figures 3A to 3D is a cross-sectional view showing an example of a manufacturing method of the adhesive sheet 3. In this manufacturing method, the adhesive sheet 3 is manufactured by molding the block-shaped composition 1 having fluidity into a sheet shape using a sheet mold 5. Specifically, first, as shown in Figure 3A , the composition 1 and the sheet mold 5 are prepared. The composition 1 contains at least the main components (i.e., EPDM, a crosslinking agent, and carbon black) of the above-described adhesive sheet 3. The composition 1 can be paste-like or pellet-like. The sheet mold 5 is an example of a press mold. Here, the sheet mold 5 includes a lower mold 5a having a molding space 6 and an upper mold 5b that closes the molding space 6 of the lower mold 5a.

[0041] The thickness (average thickness) t of the molding space 6 of the lower mold 5a at the time of closing mIt can be about 0.1 mm or more, preferably 0.5 mm or more. Thereby, it is possible to prevent the adhesive sheet 3 from decreasing in hardness after molding, to improve the mold releasability, and to improve the moldability and workability. Further, the thickness t at the time of clamping m It can be about 5.0 mm or less, preferably 3.0 mm or less, or 2.0 mm or less, for example, 1.0 mm or less. Thereby, it is possible to manufacture the weather strip 10 in which the adhesive portion 30 is not conspicuous and the appearance quality is particularly excellent.

[0042] Next, the composition 1 is put into the molding space 6 of the prepared lower mold 5a. Next, as shown in FIG. 2B, the upper mold 5b is closed with respect to the lower mold 5a, and the composition 1 is sandwiched between the lower mold 5a and the upper mold 5b. At this time, the sheet-like mold 5 can be appropriately heated, pressurized, or the like. Thereby, the composition 1 is formed into a sheet shape. Next, as shown in FIG. 2C, the upper mold 5b is opened, and the adhesive sheet 3 is taken out from the lower mold 5a. At this time, in the related art, for example, as described above, when the applied pressure is released and the adhesive sheet 3 is taken out from the sheet mold 5, the adhesive sheet is easily elastically deformed. Specifically, the dimension in the thickness direction is easily increased by an amount of decrease in the length direction. In view of this, in the present technology, it is possible to prevent the dimension of the adhesive sheet 3 from increasing in the thickness direction. As described above, as shown in FIG. 2D, it is possible to manufacture the adhesive sheet 3 having a substantially uniform thickness t. Figure 3B Figure 3C Figure 3D

[0043] In the vulcanization and bonding step, for example, first, a pair of end portions of the weather strip material are opposed to each other at a predetermined interval. Next, the adhesive sheet 3 is disposed between the opposed end portions. Next, the adhesive sheet 3 is vulcanized to crosslink and cure the EPDM. As a result, the end portions of the weather strip material are crosslinked and bonded to each other (vulcanized and bonded in this case) by the adhesive sheet 3. The method of bonding the end portions of the weather strip material to each other is not particularly limited and can be the same as in the related art. In the preferred embodiment, this step can be performed, for example, using the manufacturing apparatus described in Patent Literature 1. The manufacturing apparatus described in Patent Literature 1 includes a holding mechanism having a pair of holding molds disposed to face each other and capable of moving the pair of holding molds in a direction in which they approach and depart from each other, and a heater for heating the holding molds.

[0044] ​​​When this step is performed using the manufacturing apparatus, for example, first, the opposite end portions of the vulcanized weather strip material are disposed in the pair of holding molds, respectively. The adhesive sheet 3 is disposed between the pair of holding molds. Next, the pair of holding molds are relatively brought close to each other, and the pair of holding molds are brought into contact with each other in a state of sandwiching the adhesive sheet 3. In this state, the heater is driven to heat the portion (contact surface portion) of the adhesive sheet 3 that is in contact with the weather strip material. The heating temperature can be adjusted to accelerate the cross-linking reaction (vulcanization reaction) at least in the contact surface portion of the adhesive sheet 3. For example, the pair of holding molds can be heated at about 180°C or higher, for example, 180°C to 250°C. As a result, the contact surface portion of the adhesive sheet 3 can be softened and mixed with the weather strip material, and the adhesive sheet 3 can be properly cross-linked and solidified.

[0045] As described above, by performing this step using the manufacturing apparatus described in Patent Document 1, the opposite end portions of the weather strip material can be bonded and integrated while maintaining the good sealability of the seal portion 24.

[0046] <<Adhesive sheet for weather strip>>

[0047] Next, the adhesive sheet 3 will be described. As described above, the adhesive sheet 3 is used to form the bonding portion 30 of the weather strip 10. The adhesive sheet 3 is used to bond the opposite end portions of the weather strip material. The adhesive sheet 3 is a composition containing ethylene propylene diene rubber (EPDM), a cross-linking agent, and carbon black as main mixed components.

[0048] The EPDM is a base polymer obtained by copolymerizing ethylene, propylene, and a diene. The EPDM is not particularly limited, and those EPDMs used for such applications in the related art can be used alone or in combination of two or more. Although not particularly limited, when the total amount of the composition constituting the adhesive sheet 3 is 100% by volume, the mixing ratio of the EPDM can be higher than the mixing ratio of the carbon black. The mixing ratio of the EPDM can be about 30% by volume or more, typically 40% by volume or more, for example, 50% by volume or more, and can be about 89% by volume or less, typically 80% by volume or less, for example, 70% by volume or less, and further 60% by volume or less. By setting the content of the EPDM to a predetermined value or more, at least one of water resistance, weather resistance, heat resistance, and elasticity can be improved. Further, by setting the content of the EPDM to the above range, a weather strip that is good in appearance and excellent in rust resistance of the body panel can be properly obtained.

[0049] The crosslinking agent is a component for crosslinking the EPDM. The crosslinking agent is not particularly limited, and those crosslinking agents used in the prior art for such applications can be used alone or in combination of two or more. Examples of the crosslinking agent are vulcanizing agents. Specific examples of the vulcanizing agent include sulfur crosslinking agents such as sulfur, sulfur dichloride, dithiodimorpholine (DTDM), dithiodicaproamide (DTDC), and alkylphenol disulfide (APDS). Although not particularly limited, the mixing ratio PHR (parts per hundred of rubber) of the crosslinking agent can be about 0.1 to 20 parts by mass, typically 0.2 to 10 parts by mass, for example, 0.5 to 5 parts by mass, when the EPDM is 100 parts by mass.

[0050] The carbon black is a component for improving the mechanical properties (e.g., strength) of the composition containing the EPDM as the base polymer by adding to the composition. The carbon black is not particularly limited, and those carbon blacks used in the prior art for such applications can be used alone or in combination of two or more. Although not particularly limited, the average particle diameter of the carbon black (corresponding to the particle diameter at which 50% is accumulated from the fine particle side in the number-based particle size distribution based on electron microscope observation) can be about 1 nm to 1000 nm, preferably 10 nm to 100 nm, for example, 40 nm to 90 nm. The specific surface area of the carbon black (a value obtained by analyzing the surface area measured by using a nitrogen gas constant volume adsorption method (nitrogen adsorption method) using a BET method) can be about 1 m 2 / g to 1000 m 2 / g, preferably 10 m 2 / g to 100 m 2 / g, for example, 20 m 2 / g to 50 m 2 / g. The iodine adsorption amount (a value measured according to JIS-K6217-1:2015) can be about 1 mg / g to 100 mg / g, preferably 10 mg / g to 50 mg / g, for example, 20 mg / g to 40 mg / g. The DBP absorption of the carbon black (measured according to JI-K6217-1:2008) can be about 10 ml / 100g to 1000 ml / 100g, preferably 50 ml / 100g to 200 ml / 100g, for example, 100 ml / 100g to 150 ml / 100g. By satisfying at least one of the above-described properties (preferably two or more), at least one of the workability at the time of producing the adhesive sheet 3, the reinforcement of the adhesive sheet 3, the appearance quality, and the rust resistance of the body panel can be improved.

[0051] Although not particularly limited, when the EPDM is 100 parts by mass, the mixing ratio of the carbon black PHR (per 100 parts of rubber) can be about 1 part by mass to 200 parts by mass, generally 10 parts by mass to 100 parts by mass, for example, 40 parts by mass to 80 parts by mass, or 60 parts by mass to 74 parts by mass. When the content of the carbon black is within the above range, the weather strip 10 can be given appropriate reinforcement to the adhesive sheet 3.

[0052] Although not particularly limited, when the total amount of the composition constituting the adhesive sheet 3 is set to 100% by volume, the mixing ratio of the carbon black can be about 5% by volume or more, preferably 10% by volume or more, more preferably 11% by volume or more, and particularly preferably 15% by volume or more. The mixing ratio of the carbon black can be less than the mixing ratio of the EPDM, and can be about 30% by volume or less, preferably 20% by volume or less, more preferably 19% by volume or less, and particularly preferably 16% by volume or less. When the mixing ratio of the carbon black is defined as a volume ratio and set to a predetermined value or more, a weather strip 10 in which the adhesive portion 30 is not conspicuous and has a good appearance can be obtained. Furthermore, when the mixing ratio of the carbon black is defined as a volume ratio and set to a predetermined value or less, a desired volume resistivity can be appropriately achieved, and rusting of the vehicle body panel through the adhesive portion 30 can be prevented at a high level.

[0053] The reason why the mixing ratio of the carbon black is defined on a volume basis is that the specific gravity greatly varies depending on the mixed components. For example, the specific gravity of the carbon black (specific gravity: 1.8) and the specific gravity of the EPDM (specific gravity: 0.87) differ by two times or more. The specific gravity of the carbon black (specific gravity: 1.8) and the specific gravity of the vulcanization activator described later, for example, zinc oxide (specific gravity: 5.2) can differ by five times or more. According to the research of the present inventors, by defining the mixing ratio of the carbon black on a volume basis, the range in which the effects of the present disclosure can be exhibited can be more accurately defined than when the mixing ratio is defined on a mass basis.

[0054] In addition to the above-described EPDM, crosslinking agent, and carbon black, the adhesive sheet can also include other mixed components (arbitrary components). Examples of the arbitrary components include plasticizers (softening agents), fillers other than carbon black, vulcanization activators, vulcanization accelerators, processing aids, defoaming agents, blowing agents, antioxidants, and coloring agents. These components used for such applications in the related art can be used alone or in combination of two or more. Although not particularly limited, when the EPDM is 100 parts by mass, the total mixing ratio PHR (per 100 parts of rubber) of each component can be about 100 parts by mass or less, for example, 10 parts by mass to 100 parts by mass, 30 parts by mass to 80 parts by mass, or 50 parts by mass to 70 parts by mass.

[0055] Examples of the plasticizer include paraffin process oil. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the plasticizer can be about 10 parts by mass to 80 parts by mass, generally 20 parts by mass to 70 parts by mass, for example, 30 parts by mass to 60 parts by mass, when the EPDM is 100 parts by mass. By setting the content of the plasticizer to be more than a predetermined value, it is possible to reduce the viscosity of the composition 1, and it is possible to improve the workability at the time of manufacturing the adhesive sheet 3. Further, it is possible to appropriately obtain the adhesive portion 30 in which the electrical conductivity is reduced. Further, by setting the content of the plasticizer to be less than a predetermined value, it is possible to improve the hardness of the adhesive sheet 3.

[0056] Examples of the filler other than carbon black include insulating inorganic fillers generally called white inorganic fillers. Specific examples include clay, talc, diatomaceous earth, mica, silicic acid, silicate, calcium carbonate, and the like. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the filler other than carbon black (generally, white inorganic fillers) is generally less than the mixing ratio of carbon black, and can be about 20 parts by mass or less, generally 10 parts by mass or less, for example, 5 parts by mass or less, when the EPDM is 100 parts by mass.

[0057] Examples of the vulcanization activator include zinc oxide. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the vulcanization activator is generally less than the mixing ratio of carbon black, and can be about 20 parts by mass or less, generally 10 parts by mass or less, for example, 5 parts by mass or less, when the EPDM is 100 parts by mass. The mixing ratio PHR of the vulcanization activator can be about 0.1 parts by mass or more, for example, 1 part by mass or more.

[0058] Examples of the vulcanization accelerator include dipentamethylene thiuram tetrasulfide (DPTT) of thiuram type, zinc N-ethyl N-phenyl dithiocarbamate (ZnEPDC) of dithiocarbamate type, and 4-(-2-benzothiazyl disulfide) morpholine (MDB) of thiazole type. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the vulcanization accelerator is generally less than the mixing ratio of carbon black, and can be about 20 parts by mass or less, generally 10 parts by mass or less, for example, 5 parts by mass or less, when the EPDM is 100 parts by mass. The mixing ratio PHR of the vulcanization accelerator can be about 0.1 parts by mass or more, for example, 1 part by mass or more.

[0059] Examples of the processing aid include fatty acids such as stearic acid and lubricants such as fatty acid esters. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the processing aid is generally less than the mixing ratio of carbon black, can be about 20 parts by mass or less, generally 10 parts by mass or less, for example, 5 parts by mass or less, when the EPDM is 100 parts by mass. The mixing ratio PHR of the processing aid can be 0.1 parts by mass or more, for example, 1 part by mass or more.

[0060] Examples of the defoaming agent include calcium oxide. Although not particularly limited, the mixing ratio PHR (per hundred parts of rubber) of the defoaming agent is generally less than the mixing ratio of the carbon black, and can be about 30 parts by mass or less, generally 20 parts by mass or less, for example, 10 parts by mass or less, when the EPDM is 100 parts by mass. The mixing ratio PHR of the defoaming agent can be about 0.1 parts by mass or more, generally 1 parts by mass or more, for example, 5 parts by mass or more. Examples of the blowing agent include p,p'-oxybisbenzenesulfonylhydrazide (OBSH), sodium bicarbonate, and heat-expandable microcapsules.

[0061] When a molded product is produced by placing the composition constituting the adhesive sheet 3 in a predetermined mold (for example, a sheet mold 5 as shown in Figure 3A FIG. 2) and press-molding the composition at 50°C under a pressure of 100 Kgf / cm 2 The thickness change ratio represented by the above formula (1) is preferably 100% or less. The thickness change ratio is preferably 80% or less, and more preferably 65% or less. As a result, it is possible to prevent the dimension of the composition from increasing in the thickness direction after press-molding, and the adhesive portion 30 is less conspicuous when the weather strip 10 is installed in the vehicle. Therefore, it is possible to improve the appearance quality of the weather strip 10. The thickness change ratio is generally 0% or more, and can be about 10% or more, or 20% or more, for example, 50% or more.

[0062] The adhesive sheet 3 can have a volume resistivity of 1.0 x 10 6 Ω·cm or more (a value measured according to the two-ring electrode method of JIS-K6271-1:2015 (thickness of test piece: 2 mm)). The volume resistivity is preferably 1.5 x 10 6 Ω·cm or more, and more preferably 1.9 x 10 6 Ω·cm or more. As a result, it is possible to reduce the electrical conductivity of the adhesive portion 30, and it is possible to prevent the body panel from rusting through the adhesive portion 30 when the weather strip 10 is installed in the vehicle.

[0063] As described above, according to the adhesive sheet 3, it is possible to form the adhesive portion 30 between the opposing end portions of the weather strip material without causing discomfort. As a result, it is possible to obtain a continuous and integrated appearance between the main body portion 20 and the adhesive portion 30, and it is possible to obtain the weather strip 10 having a good appearance. Furthermore, according to the adhesive sheet 3, it is possible to obtain the weather strip 10 in which the electrical conductivity of the adhesive portion 30 is reduced and the body panel does not rust through the adhesive portion 30. Furthermore, the door opening portion of the vehicle and the door can be closed without gaps, and excellent sealability can be achieved.

[0064] The technology disclosed herein can be applied to any form of weather strip. For example, the technology can be applied to a weather strip that seals between a peripheral edge of an opening portion and an opening / closing member in a door portion (e.g., a back door portion, a front door portion, or a rear door portion), a trunk portion, or a moon roof portion of a vehicle. In particular, the technology can be suitably applied to a weather strip 10 as shown in FIG. 1, which is a ring-shaped weather strip. Figure 1

[0065] Hereinafter, examples related to the technology disclosed herein will be described, and the technology is not intended to be limited to what is shown in the examples.

[0066] [Preparation of compositions (Examples 1 to 3, Comparative Examples 1 and 2)]

[0067] The compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were prepared by mixing the mixing components shown in Table 1 at the mixing ratio PHR (parts per hundred of rubber) shown in Table 2 and kneading the mixed components by a kneader. The compositions of Examples 1 to 3 and Comparative Examples 1 and 2 differ only in the kind and / or mixing ratio of carbon black. Then, each composition was evaluated for electrical conductivity (volume resistivity), thickness change rate, and appearance quality as follows.

[0068] [Table 1]

[0069] Table 1. Mixing components of compositions

[0070]

[0071] [Table 2]

[0072] Table 2. Mixing ratio PHR and evaluation results of compositions

[0073]

[0074] [Calculation formula of mixing ratio (volume basis) of carbon black]

[0075] Table 2 also shows the mixing ratio (volume % when the total amount of the composition is defined as 100 volume %) of carbon black on a volume basis calculated by the following calculation formula.

[0076] Volume Vi of each mixing component = mixing ratio PHR / specific gravity

[0077] Mixing ratio (volume %) of carbon black = (volume of carbon black / total mixing volume ∑Vi) x 100 For example, in the case of Example 3, the volume Vi and the mixing ratio (volume basis) of each mixing component can be calculated as shown in Table 3.

[0078] [Table 3]

[0079] Table 3. Volume Vi and mixing ratio (volume basis) of each mixing component in Example 3 ​

[0080]

[0081] [Conductivity Evaluation (Volume Resistivity)]

[0082] First, the above-prepared composition was pressed into a sheet with a thickness of 2 mm to prepare a test piece. Next, the volume resistivity was measured according to the double-ring electrode method of JIS-K6271-1:2015. A digital ultra-high resistance / microammeter 5451 (manufactured by ADC Corporation) was used as the testing apparatus. The volume resistivity (ρ) was calculated using the following formula (2): ρ (unit: Ω·cm)=(V / I)×(π×d²) / (4×t)(2). Here, V is the voltage applied to the test piece (volts), I is the current after one minute of voltage application (amperes), π is pi, d is the outer diameter of the main electrode (cm), and t is the thickness of the test piece (cm). The volume resistivity was 1.0×10⁻⁶. 6 Test pieces with a resistivity greater than Ω·cm are rated as "○", and those with a volume resistivity less than 1.0 × 10⁻⁶ are rated as "○". 6 The test piece with a Ω·cm value was rated "×". The results are shown in Table 2.

[0083] [Evaluation of thickness change rate]

[0084] First, place the composition prepared as described above into Figure 3A Sheet mold 5 (thickness tm at mold closing: 0.5mm), and at 50℃ and 100Kgf / cm². 2 Press down for 60 seconds to prepare the molded part. Then, read the thickness (mm) of the molded part 30 minutes after releasing the press, and calculate the thickness change rate (%) of the molded part according to the above formula (1). Then, when the thickness change rate is less than 100% (in other words, the thickness t of the molded part 30 minutes after releasing the press is equal to the mold thickness t when the mold is closed), the thickness change rate is calculated. m When the thickness change rate is less than twice the standard value, it is judged as "○", and when the thickness change rate exceeds 100%, it is judged as "×". The results are shown in Table 2.

[0085] [Evaluation of appearance quality]

[0086] By using the molded piece produced for measuring the above thickness change rate, the opposite end portions of the weather strip material were adhered to each other. Specifically, molding was performed using the production apparatus described in Patent Literature 1, and an adhering portion was formed between the pair of end portions of the weather strip material. In this way, a weather strip having an adhering portion formed by the molded piece between the main body portions formed by the weather strip material was obtained. Then, the appearance quality of the obtained weather strip was visually evaluated. The results are shown in Table 2. In Table 2, a weather strip in which the adhering portion was less conspicuous than that of Comparative Example 1 was judged to be "good" with the weather strip of Comparative Example 1 as a standard, and a weather strip in which the appearance quality was particularly excellent was judged to be "excellent".

[0087] As shown in the evaluation results of Table 2, in Comparative Example 1, the volume resistivity was 1.0 x 10 6 Ω·cm or more, and the electric conductivity decreased, but the thickness change rate greatly exceeded 100%. In Comparative Example 2, although the thickness change rate decreased to 100% or less, the volume resistivity was significantly lower than 1.0 x 10 6 Ω·cm. In contrast, in all of Examples 1 to 3, the volume resistivity was 1.0 x 10 6 Ω·cm, and the electric conductivity decreased. Furthermore, a weather strip in which the thickness change rate was less than 100% and which had a good appearance in which the adhering portion was relatively less conspicuous compared to Comparative Example 1 was obtained.

[0088] The specific examples of the technology disclosed herein have been described in detail above, and these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the above-described specific examples.

Claims

1. An adhesive sheet for a weather strip, the adhesive sheet being configured to adhere opposite end portions of a weather strip material to each other, wherein the adhesive sheet is a composition containing at least EPDM, a crosslinking agent, and carbon black, the thickness change rate = ((thickness of a molded article after 30 minutes of release from pressurization - thickness of a mold) / thickness of the mold) x 100%, and a volume resistivity of 1.0 x 10 6 Ω·cm or more, When the composition is placed in a mold and press-molded at 100 Kgf / cm 2 and 50°C for 60 seconds to produce a molded piece, the molded piece has a thickness variation rate of 100% or less, the thickness variation rate being represented by formula (1), when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 16% by volume or less.

2. A weather strip comprising: a main body portion having end portions; and an adhesive portion that adheres opposite end portions of the main body portion to each other, wherein the adhesive portion is formed from a crosslinked product of the adhesive sheet of claim 1.

3. The weather strip according to claim 2, wherein the adhesive sheet has a thickness of 1.0 mm or less.

4. A weather strip comprising: a main body portion having end portions; and an adhesive portion that adheres opposite end portions of the main body portion to each other, wherein the adhesive portion is formed from a crosslinked product of an adhesive sheet, and the adhesive sheet satisfies all of the following conditions: the composition contains at least EPDM, a crosslinking agent, and carbon black; when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 16% by volume or less; and 5. The weather strip according to claim 4, wherein the adhesive sheet has a thickness of 1.0 mm or less.

6. A manufacturing method of a weather strip including a main body portion having end portions and an adhesive portion that adheres opposite end portions of the main body portion to each other, the method comprising: The volume resistivity was 1.0 x 10 6 Ω·cm or more based on the double ring electrode method of JIS-K6271-1:2015 of a test piece with a thickness of 2 mm. preparing a weather strip material for forming the main body portion and an adhesive sheet for forming the adhesive portion; and crosslinking the adhesive sheet by placing the adhesive sheet between opposite end portions of the weather strip material, wherein the adhesive sheet satisfies all of the following conditions: the composition contains at least EPDM, a crosslinking agent, and carbon black; the thickness change rate = ((thickness of a molded article after 30 minutes of release from pressurization - thickness of a mold) / thickness of the mold) x 100%, and when the total amount of the composition constituting the adhesive sheet is defined as 100% by volume, the mixing ratio of the carbon black is 11% by volume or more and 16% by volume or less.

7. The manufacturing method according to claim 6, wherein the preparing includes manufacturing the adhesive sheet by charging the composition into a press mold and press-molding the composition. The volume resistivity was 1.0 x 10<5> Ω·cm or more based on the double ring electrode method of JIS-K6271-1:2015 of a test piece with a thickness of 2 mm. 6 Ω·cm or more; When the composition is placed in a mold and press-molded at 100 Kgf / cm 2 and 50°C for 60 seconds to produce a molded piece, the molded piece has a thickness variation rate of 100% or less, the thickness variation rate being represented by formula (1); 8. The manufacturing method according to claim 7, wherein the preparing includes using the press mold having a thickness of 0.5 mm or more at the time of closing of the mold.

9. The manufacturing method according to any one of claims 6 to 8, wherein the preparing includes preparing the adhesive sheet having a thickness of 1.0 mm or less. ​ ​ ​ ​

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