Weather stripping

Abstract

To achieve both low specific gravity and low water absorption in a weather strip. [Solution] A weather strip (10) is attached to an automobile and has a hollow seal part (11) in which a hollow part (13) is formed. The hollow seal part (11) has a foam wall part (12) which is at least a part of the wall forming the hollow part (13). The foam wall part (12) is at least partially derived from thermally expandable microcapsules with a density of 200 pieces / mm 2 The above bubbles are formed, the thickness is 1.0 mm or more and 2.0 mm or less, and the specific gravity is 0.45 or less.

Description

[Technical field]

[0001] The present invention relates to a weather strip. [Background technology]

[0002] Attempts have been made to reduce the specific gravity of weather strips attached to automobiles in order to reduce their weight. One known method for reducing the specific gravity is to foam the weather strip material to make it sponge-like.

[0003] For example, Patent Document 1 discloses a weather strip for automobiles obtained by molding a silicone rubber sponge composition containing thermally expandable microcapsules and an organic foaming agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-12797 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the weather strip for automobiles described in Patent Document 1 has room for improvement in terms of maintaining a low water absorption rate while reducing the specific gravity.

[0006] An object of one aspect of the present invention is to provide a weather strip or the like that achieves both a low specific gravity and a low water absorption rate. [Means for solving the problem]

[0007] In order to solve the above problems, a weatherstrip according to one aspect of the present invention is a weatherstrip that is attached to an automobile and has a hollow seal portion in which a hollow portion is formed, the hollow seal portion has a foamed wall portion that is at least a part of a wall that forms the hollow portion, and the foamed wall portion has a density of 200 foam pieces / mm in any cross section. 2 At least a part of the bubbles is derived from the thermally expandable microcapsules, has a thickness of 1.0 mm or more and 2.0 mm or less, and has a specific gravity of 0.45 or less. Effect of the Invention

[0008] According to one aspect of the present invention, a weather strip or the like that achieves both a low specific gravity and a low water absorption rate can be realized. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing a schematic left side surface of an automobile to which a weather strip according to a first embodiment is attached. [Diagram 2] FIG. 2 is a diagram showing a schematic shape of a weatherstrip according to the first embodiment, and is a cross-sectional view taken along line II-II in FIG. [Diagram 3] 4 is a cross-sectional photograph of a foamed wall portion of a weather strip according to Example 1 and a diagram showing the number of foams. FIG. [Figure 4] FIG. 4 is a cross-sectional photograph of a foamed wall portion of a weather strip according to Comparative Example 1 and a diagram showing the number of foams. [Diagram 5] FIG. 13 is a cross-sectional photograph of a foamed wall portion of a weather strip according to Comparative Example 2 and a diagram showing the number of foams. [Figure 6] FIG. 13 is a cross-sectional photograph of a foamed wall portion of a weather strip according to Comparative Example 3 and a diagram showing the number of foams. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, the term "A to B" indicating a range of numerical values ​​indicates "A or more and B or less", including the numerical values ​​at the ends.

[0011] [Weather Strip 10] Fig. 1 is a side view showing a schematic diagram of the left side of an automobile 1 to which a weatherstrip 10 according to this embodiment is attached. Fig. 2 is a schematic diagram showing the shape of the weatherstrip 10 according to this embodiment, and is a cross-sectional view taken along line II-II in Fig. 1. In the example of Fig. 1, the upper side corresponds to the vertical upper side, the lower side corresponds to the vertical lower side, the left side corresponds to the front side, and the right side corresponds to the rear side. In addition, in the example of Fig. 2, the left side corresponds to the vehicle exterior side, and the right side corresponds to the vehicle interior side.

[0012] As shown in Fig. 1, an automobile 1 is provided with a door 2 for closing a door opening. A flange 3 is formed on the peripheral portion of the door 2 on the interior side of the vehicle. As shown in Fig. 2, a weatherstrip 10 is attached to the flange 3, and is a member that seals between the peripheral portion of the door opening in the automobile 1 and the door 2. The weatherstrip 10 may abut against another sealing member, such as a door side seal 4 attached to the door 2.

[0013] The weather strip 10 is not limited to being attached to the door 2 of the automobile 1, and may be attached to any position on the automobile 1. For example, the weather strip 10 may be attached to the periphery of an engine room opening or to an engine hood, or may be attached to the periphery of a trunk opening or to a trunk door.

[0014] (Weatherstrip 10 configuration) 2, the weatherstrip 10 has a hollow seal portion 11, a foamed wall portion 12, a base portion 14, and a lip 15. As long as the weatherstrip 10 has the hollow seal portion 11 and the foamed wall portion 12, the configuration of other portions is not particularly limited. For example, the weatherstrip 10 does not need to have the lip 15, and may have multiple lips other than the lip 15.

[0015] The base 14 is a portion of the weatherstrip 10 that is attached to the flange 3. The manner in which the base 14 is attached to the flange 3 is not particularly limited. For example, the base 14 may be attached to the flange 3 with an adhesive or the like, may be attached via an attachment member such as a clip, or may be attached by fitting into a groove or the like formed in the flange 3.

[0016] The lip 15 is a tongue-shaped portion that comes into contact with the door side seal 4 of the door 2. The lip 15 prevents the weather strip 10 from bending excessively when the door 2 is in a closed state, and enables the position of the weather strip 10 to be stably maintained.

[0017] The hollow seal portion 11 is a portion that contacts the peripheral portion of the door opening of the automobile 1 when the door 2 is closed, and seals between the peripheral portion of the door opening and the door 2. The hollow seal portion 11 has a hollow portion 13 formed therein. According to the hollow seal portion 11 having the hollow portion 13 formed therein, when the hollow seal portion 11 contacts the peripheral portion of the door opening of the automobile 1, the hollow seal portion 11 is likely to elastically deform according to the shape of the peripheral portion and the contact state. Therefore, the gap between the peripheral portion of the door opening and the door 2 can be tightly sealed. This can improve the waterproofness and soundproofing when the door 2 is closed.

[0018] The hollow seal portion 11 has, at least in a portion thereof, a foam wall portion 12, which will be described later.

[0019] (Weatherstrip 10 material) The material of the weatherstrip 10 may be a material containing an elastomer as a main component. In this specification, the term "elastomer" refers to a polymer having elasticity, and includes rubber and thermoplastic elastomer (TPE). The weatherstrip 10 may contain various additive components other than the elastomer as necessary.

[0020] Examples of rubber include vulcanized rubber, including natural and synthetic rubbers, etc. Examples of TPEs include block copolymers having hard and soft segments, particularly polystyrene-, olefin-, polyvinyl chloride-, polyurethane-, polyester-, and polyamide-based TPEs.

[0021] The elastomer may be an ethylene-propylene-diene terpolymer rubber (EPDM) from the viewpoint of improving the elasticity of the weatherstrip 10. Alternatively, from the viewpoint of reducing the specific gravity of the weatherstrip 10, saving energy during production, or improving recyclability, the elastomer may be a TPE, and in particular an olefin-based TPE (TPO).

[0022] The material of the weatherstrip 10 may be in a non-foamed state (solid state) or in a foamed state (sponge state). From the viewpoint of reducing the specific gravity of the weatherstrip 10, it is preferable that at least a portion of the weatherstrip 10 is made in a sponge state. In the weatherstrip 10 according to this embodiment, the foamed wall portion 12, which is at least a portion of the hollow seal portion 11, is formed in a sponge state. The portions of the weatherstrip 10 other than the foamed wall portion 12 may be formed in a sponge state.

[0023] (Foam wall section 12) The foam wall portion 12 is at least a part of the wall forming the hollow portion 13 in the hollow seal portion 11. The foam wall portion 12 is formed at a density of 200 foam pieces / mm in any cross section in the hollow seal portion 11. 2It is defined as a portion in which a number of bubbles equal to or greater than 1.0 mm are formed, the thickness T is 1.0 mm or more and 2.0 mm or less, and the specific gravity is 0.45 or less.

[0024] The hollow seal portion 11 may be entirely configured as the foamed wall portion 12, or may only partially have the foamed wall portion 12. When the hollow seal portion 11 only partially has the foamed wall portion 12, the remaining portion of the hollow seal portion 11 is preferably foamed and sponge-like, and further, it is preferable that either the thickness T or the specific gravity satisfy the numerical range defined for the foamed wall portion 12.

[0025] The foam wall 12 has a density of 200 pieces / mm 2 The number of bubbles formed is equal to or greater than 1 mm. 2 As long as the cross section has the above area, it may be a cross section cut from any direction of the foamed wall portion 12. The number of bubbles observed in any cross section is obtained by visually counting. In addition, when a part of a bubble is connected to another bubble to form a void, the bubbles are counted as one bubble. In other words, the number of bubbles is defined as the number of continuous voids formed.

[0026] At least some of the bubbles formed in the foamed wall portion 12 are bubbles derived from the thermally expandable microcapsules. The bubbles formed in the foamed wall portion 12 can be classified into first bubbles, which are bubbles derived from the thermally expandable microcapsules, and second bubbles, which are other bubbles.

[0027] The first bubbles are bubbles formed by the expansion of thermally expandable microcapsules. Thermally expandable microcapsules are substances that expand when heated. Thermally expandable microcapsules are in a form in which a chemical substance that gasifies when heated, such as a hydrocarbon, or a gas that expands when heated is covered with a shell. Even when the foaming start temperature is reached, the shell of the thermally expandable microcapsule maintains its shape. The shell may be softened by heating. On the other hand, when the foaming start temperature is reached, the chemical substance or gas covered by the shell expands within the shell. The first bubbles can be formed in the manufacturing process of the weather strip 10 by adding a thermally expandable microcapsule to the foam wall portion 12 and heating to a temperature equal to or higher than the foaming start temperature of the thermally expandable microcapsule.

[0028] The type of thermally expandable microcapsule is not particularly limited, and known thermally expandable microcapsules may be used. The thermally expandable microcapsule may be, for example, a form in which a shell formed of a resin covers a hydrocarbon. Such thermally expandable microcapsules include Matsumoto Microsphere (registered trademark) manufactured by Matsumoto Yushi Seiyaku Co., Ltd., and include F and FN series (unexpanded bodies) and FE, F-DE, and MFL (expanded bodies).

[0029] The second bubbles are bubbles formed in the foamed wall portion 12 other than the first bubbles. The second bubbles may be, for example, bubbles formed by foaming a chemical foaming agent. A chemical foaming agent is a solid such as a powder at room temperature, but when heated to a temperature equal to or higher than the foaming start temperature, it generates a gas such as nitrogen gas or carbon dioxide gas to foam the material. The second bubbles can be formed, for example, in the manufacturing process of the weather strip 10, by adding a chemical foaming agent to the foamed wall portion 12 and heating to a temperature equal to or higher than the foaming start temperature of the chemical foaming agent.

[0030] The type of chemical foaming agent is not particularly limited, and any known chemical foaming agent may be used. Examples of chemical foaming agents include azodicarbonamide (ADCA), 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH), and N,N'-dinitropentamethylenetetramine (DPT).

[0031] The second bubbles are not limited to bubbles derived from a chemical foaming agent, and may be any bubbles other than the first bubbles. In other words, the second bubbles may include bubbles derived from sources other than the thermally expandable microcapsules and the chemical foaming agent.

[0032] The first and second bubbles can be distinguished by whether or not the shell material of the thermally expandable microcapsule after expansion is present in at least a part of the inner wall surrounding the bubble in the foamed wall portion 12. The shell material of the thermally expandable microcapsule is, for example, a thermoplastic polymer material, and examples of the material include an acrylic resin and a vinylidene chloride resin.

[0033] The first bubbles are unlikely to join with other first or second bubbles to form a single bubble, since the voids formed by foaming are covered with the thermally expandable microcapsules. Therefore, the foamed wall 12 can have a high bubble density by having the first bubbles. Here, "high bubble density" refers to a high number of bubbles per unit area in any cross section of the foamed wall 12.

[0034] The greater the number density of the bubbles formed in the foamed wall portion 12, the greater the total volume of the voids formed in the foamed wall portion 12, thereby reducing the specific gravity and reducing the water absorption rate of the foamed wall portion 12. If the number density of the bubbles is large, the size of each bubble is relatively small, so even if water penetrates into one bubble, the amount of water penetrating into the foamed wall portion 12 is small. Therefore, the water absorption rate of the foamed wall portion 12 can be maintained low.

[0035] On the other hand, when the number density of the air bubbles is low, the volume of each individual air bubble increases as the specific gravity is reduced. This is because in order to reduce the specific gravity of the foamed wall portion 12, it is necessary to increase the total volume of the voids in the foamed wall portion 12. Therefore, the lower the number density of the air bubbles, the greater the amount of water that penetrates into the foamed wall portion 12 when water penetrates into one air bubble, and the water absorption rate of the foamed wall portion 12 increases. When the foamed wall portion 12 is provided with 200 air bubbles / mm 2 If the above-mentioned bubbles are formed, the specific gravity of the foamed wall portion 12 can be reduced, and the water absorption rate can also be reduced.

[0036] Furthermore, if the number density of bubbles formed in the foamed wall portion 12 is large, the area ratio and density of the portion (other than voids) occupied by materials such as rubber in any cross section of the foamed wall portion 12 can also be increased. This improves the adhesive strength when bonding any cross sections of the foamed wall portion 12 together, such as when bonding the end faces of the weatherstrip 10 together. This is because the area of ​​the portions that are in contact and bonded to each other increases at the bonding surfaces. When the number of bubbles formed in the foamed wall portion 12 is 200 bubbles / mm 2 If the thickness is more than this, the adhesive strength between any two cross sections of the foam wall portion 12 can be made good.

[0037] It is also known that the surface roughness of a foamed material increases as the bubbles become larger. By increasing the number density of the bubbles formed in the foamed wall portion 12, the individual bubbles become smaller, and the surface roughness of the surface of the foamed wall portion 12 can be reduced. When the number density of the bubbles formed in the foamed wall portion 12 is 200 bubbles / mm 2 If the above conditions are met, the surface of the foamed wall portion 12 can be formed smoothly, and the weather strip 10 will have a good appearance and feel.

[0038] Furthermore, by increasing the number density of the air bubbles formed in the foamed wall portion 12, it is possible to reduce the formation of creases in the foamed wall portion 12. This is because a material such as rubber is densely formed inside the foamed wall portion 12, and the dense three-dimensional structure formed inside the foamed wall portion 12 easily reinforces the restoring elastic force that restores the creases on the surface of the foamed wall portion 12 to their original state.

[0039] The thickness T of the foamed wall portion 12 is 1.0 mm or more and 2.0 mm or less, and may be 1.1 mm or more and 1.5 mm or less, or may be 1.2 mm or more and 1.4 mm or less. The thickness T of the hollow seal portion 11 and the foamed wall portion 12 is the wall thickness of the wall forming the hollow portion 13 in the hollow seal portion 11, and is the length of the portion shown as thickness T in FIG.

[0040] The specific gravity of the foamed wall portion 12 is 0.45 or less, and more preferably 0.40 or less. The smaller the specific gravity of the foamed wall portion 12, the lighter the weatherstrip 10 can be. It is more preferable that the specific gravity of the entire weatherstrip 10 is 0.45 or less. The lower limit of the specific gravity of the foamed wall portion 12 is not particularly limited, but may be 0.10 or more from the viewpoint of maintaining the sealing performance of the foamed wall portion 12. In this specification, "low specific gravity" refers to a specific gravity that is a small value of 0.45 or less.

[0041] The specific gravity of the foamed wall portion 12 can be measured by a method conforming to JIS K6268:1998 using a sample separated by, for example, cutting out the foamed wall portion 12 from the weather strip 10. Specifically, the weight (g) of the sample in air is measured. Then, the weight (g) of the sample when immersed in water is measured. The specific gravity is calculated from the following formula (1): Specific gravity = weight in air / weight when immersed in water (1) The foamed wall portion 12 preferably has a water absorption rate of 5.0% or less. The foamed wall portion 12 more preferably has a water absorption rate of 4.5% or less, and even more preferably has a water absorption rate of 4.0% or less. The smaller the water absorption rate of the foamed wall portion 12, the more preferable it is, and it may be 0%. In this specification, "low water absorption rate" refers to a water absorption rate that is a small value of 5.0% or less.

[0042] The water absorption rate of the foamed wall portion 12 can be measured by the following method. The weight of a sample separated by, for example, cutting out the foamed wall portion 12 from the weather strip 10 is measured. The sample is immersed in distilled water at 23°C so that the upper end is about 50 mm below the water surface, the pressure is reduced to 17 kPa, and the sample is left for 3 minutes, after which the pressure is returned to normal pressure and the sample is left in that state for 3 minutes. The sample is then removed from the water, any water droplets on the surface are wiped off, and the weight is measured within 30 minutes. The water absorption rate is calculated from the following formula (2), where W0 is the weight (g) of the sample before the test and W1 is the weight (g) of the sample after the test: Water absorption rate (%) = (W1-W0) / W0×100 (2) In the foamed wall 12 having the above-mentioned thickness T, it has been conventionally difficult to reduce the specific gravity and the water absorption rate by foaming. 2 It has been found that by making some of the air bubbles originate from thermally expandable microcapsules, it is possible to achieve a low water absorption rate (for example, 5.0% or less) while keeping the specific gravity at 0.45 or less.

[0043] This configuration makes it possible to realize a hollow seal portion 11 (foamed wall portion 12) with a thin wall thickness and low specific gravity while maintaining a low water absorption rate. This makes it possible to reduce the weight of the weather strip 10 and the amount of material required for its manufacture. This effect also contributes to the achievement of, for example, Goal 12 "Ensure sustainable consumption and production patterns" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0044] [Method of manufacturing weatherstrip 10] The weatherstrip 10 can be manufactured by a conventionally known method. For example, the weatherstrip 10 may be manufactured by extrusion molding, molding, or a combination of these methods.

[0045] When the weatherstrip 10 is molded, the thermally expandable microcapsules and the chemical foaming agent are added to the forming material in the foam wall portion 12. By heating the foam wall portion 12 in this state, the thermally expandable microcapsules expand and the chemical foaming agent foams, forming the first and second bubbles. It is preferable that the heating of the foam wall portion 12 is also performed to mold the weatherstrip 10.

[0046] The foamed wall portion 12 may be in an embodiment that contains thermally expandable microcapsules but does not contain a chemical foaming agent. In other words, the foamed wall portion 12 may not contain the second bubbles. Even in such an embodiment, it is possible to achieve both a low specific gravity and a low water absorption rate for the foamed wall portion 12. However, since the foamed wall portion 12 contains both thermally expandable microcapsules and a chemical foaming agent, the amount of foaming can be easily increased, which is preferable from the viewpoint of achieving both a low specific gravity (high foaming) of the foamed wall portion 12 and reduced manufacturing costs.

[0047] 〔summary〕 A weatherstrip according to a first aspect of the present invention is a weatherstrip that is attached to an automobile and has a hollow seal portion in which a hollow portion is formed, the hollow seal portion having a foamed wall portion that is at least a part of a wall that forms the hollow portion, and the foamed wall portion has a density of 200 foam particles / mm in any cross section. 2 At least a part of these bubbles is derived from the thermally expandable microcapsules, has a specific gravity of 0.45 or less, and has a thickness of 1.0 mm or more and 1.5 mm or less.

[0048] A weather strip according to a second aspect of the present invention is the weather strip of the first aspect, wherein the foamed wall portion has a water absorption rate of 5.0% or less.

[0049] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0050] An embodiment of the present invention will now be described.

[0051] For the weather strips of Example 1 of the present invention and Comparative Examples 1 to 3, the foamed wall portion in the cross section cut along the line II-II shown in FIG. 1 (cross section shown in FIG. 2) was photographed with a digital microscope. 2 The number of bubbles per unit area was visually counted. Furthermore, for the weather strips of Example 1 and Comparative Example 1, the water absorption rate of the foamed wall portion was measured according to the method described in the "Description of the Invention."

[0052] All weather strips used EPDM as a forming material. The weather strip of Example 1 was manufactured by adding thermally expandable microcapsules (Matsumoto Microsphere, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and chemical foaming agents OBSH and ADCA to the foam wall as air bubble forming agents. The weather strip of Comparative Example 1 was manufactured by adding only chemical foaming agents OBSH and ADCA to the foam wall as air bubble forming agents. The weather strip of Comparative Example 2 was manufactured using a commercially available product. The detailed manufacturing conditions of the weather strip of Comparative Example 2 are unknown, but it does not contain air bubbles derived from thermally expandable microcapsules. The weather strip of Comparative Example 3 was manufactured by adding only chemical foaming agents OBSH and ADCA to the foam wall as air bubble forming agents.

[0053] 3 to 6 are cross-sectional photographs and figures showing the number of bubbles in the foamed wall portions of the weatherstrips according to Example 1 and Comparative Examples 1 to 3, respectively. For Example 1 and Comparative Example 1, the number of bubbles was counted at five points in the captured image. For Comparative Examples 2 and 3, the number of bubbles was counted at three points in the captured image.

[0054] As shown in Figs. 3 to 6, the foam wall of the weather strip of Example 1 had a density of 200 pieces / mm 2On the other hand, in the foamed wall portions of the weather strips of Comparative Examples 1 to 3, the number of bubbles formed was 100 / mm 2 The results were as follows.

[0055] Furthermore, the foamed wall portion of the weatherstrip of Example 1 had a water absorption rate of 0.8%, whereas the foamed wall portion of the weatherstrip of Comparative Example 1 had a water absorption rate of 2.0%.

[0056] From the above results, it is clear that the foamed wall of the weather strip of Example 1 is at least partially derived from thermally expandable microcapsules, with a density of 200 microcapsules / mm 2 It was shown that having a number of bubbles equal to or greater than this number results in a good water absorption rate. [Explanation of symbols]

[0057] 1. Automobiles 2 Door 3 Flange 4 Door side seal 10 Weather strip 11 Hollow seal part 12 Foam wall 13 Hollow part 14 Base 15 Lip

Claims

1. A weather strip attached to an automobile and having a hollow seal portion having a hollow portion formed therein, The hollow seal portion has a foam wall portion that is at least a part of a wall that forms the hollow portion, The foam wall portion is 200 pieces / mm in any cross section ２ or more bubbles are formed, and at least a part of these bubbles are bubbles derived from the thermally expandable microcapsules, The thickness is 1.0 mm or more and 2.0 mm or less, A weather strip having a specific gravity of 0.45 or less.

2. The weather strip according to claim 1 , wherein the foam wall portion has a water absorption rate of 5.0% or less.

Images