Sealing components

Abstract

A sealing component (1) has a plurality of insertion holes (20) for inserting a counterpart component (8), and is a cured product of a silicone rubber composition having silicone rubber and silica particles, satisfying the following conditions (a) to (d): (a) when the content of the silica particles relative to 100 parts by mass of a base polymer of the silicone rubber is set to X parts by mass, the elastic recovery rate (%) / X (parts by mass) = 3.6 to 9.6; (b) the type A durometer hardness is greater than 15 and less than 30; (c) the tensile strength at break is greater than 2.1 MPa; and (d) the dynamic friction coefficient of the surface of the insertion hole (20) is less than 2.5.

Description

Technical Field

[0001] The present invention relates to a silicone rubber-based sealing member having a plurality of insertion holes for inserting a counterpart member. Background Art

[0002] It is known that there is a sealing gasket that is arranged at the wire lead-out portion of the connector housing and seals the wire and the connector housing (for example, refer to patent document 1). The sealing gasket is made of an elastic material such as rubber, and has a plurality of insertion holes that penetrate in the thickness direction, and the wires are inserted into each insertion hole. A terminal is installed at the front end of the wire. When the wire is inserted into the insertion hole of the sealing gasket, the terminal is first inserted into the insertion hole, and the insertion hole is expanded while the terminal is passed. The terminal after passing through the insertion hole is inserted into the terminal accommodating chamber, and the wire extending from the terminal is arranged in the insertion hole. An annular lip is formed on the inner peripheral surface of the insertion hole, and the lip is in close contact with the outer periphery of the wire, thereby suppressing the intrusion of moisture into the connector housing.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-58138

[0006] Patent Document 2: Japanese Patent Application Publication No. 2018-53237 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In recent years, connector housings have become smaller and the number of wires inserted has also increased. In line with this, the number of insertion holes in the gasket has also been increased and the size has been reduced. The terminals installed at the front end of the wires are mostly made of metal and have a corner shape. Therefore, when the terminal passes through the insertion hole, there is a risk of damaging the surface of the insertion hole, resulting in reduced sealing.

[0009] In this regard, it is described in patent document 1 that, as a material for sealing members such as gaskets, silicone rubber with polyrotaxane is used to make the molecules of silicone rubber slide easily with each other, thereby reducing the damage of the sealing member. However, polyrotaxane is relatively expensive, so the cost increases. In addition, although there is no record of reducing the generation of what kind of damage in patent document 1, it is described in paragraph

[0027] that polyrotaxane is matched in order to make the stress applied from the outside easy to disperse.

[0010] In the past, as a damage to the sealing member, "cracks" existing in the state after the incision progresses on the surface have become a problem. Therefore, as a countermeasure to suppress damage (cracks), research has been conducted to improve the tear strength that takes into account the progress of the incision. In Patent Document 1, tear strength is also listed as an evaluation item for characteristics (Table 1, Table 2). In contrast, the inventors of the present invention have repeatedly conducted in-depth research on the damage of the sealing member and have obtained the following insights: In order to suppress the reduction in sealing performance, it is more necessary to suppress the generation of the incision itself than the "cracks" in the state after the incision progresses. For this reason, it cannot be solved by simply increasing the tear strength, and the previous materials cannot fully suppress the generation of incision damage.

[0011] On the other hand, in patent documentation 2, a kind of silicone rubber is described, which comprises an organopolysiloxane containing vinyl and silicon dioxide particles, and is low hardness, high tear strength and small tensile permanent deformation. However, as mentioned above, the generation of incision damage cannot be suppressed only by improving tear strength. In addition, the purpose of the silicone rubber described in patent documentation 2 is a medical molded body such as a medical tube (paragraph

[0126] ). In patent documentation 2, as a problem of paying attention to this purpose, the reduction of tensile permanent deformation is described. Tensile permanent deformation is a characteristic (tensile residual deformation) that indicates that the elongation remains after stretching without recovery, and is considered to be a characteristic different from the compression permanent deformation of residual deformation due to compression (paragraph

[0011] ). In patent documentation 2, about the damage caused by the plugging and unplugging of the other party components such as terminals, it is not the object of research.

[0012] The present invention has been made in view of such actual conditions, and an object of the present invention is to provide a silicone rubber-based sealing member which is less likely to be damaged by cuts in an insertion hole due to insertion and removal of a counterpart member.

[0013] Means used to solve problems

[0014] In order to solve the above problems, the sealing member of the present invention has a plurality of insertion holes for inserting the counterpart member, characterized in that the sealing member is a cured product of a silicone rubber composition having silicone rubber and silica particles, and satisfies the following conditions (a) to (d):

[0015] (a) when the content of the silica particles relative to 100 parts by mass of the base polymer of the silicone rubber is X parts by mass, elastic recovery rate (%) / X (parts by mass) = 3.6 to 9.6;

[0016] (b) A-type durometer hardness of 15 or more and 30 or less;

[0017] (c) a tensile strength at break of 2.1 MPa or more;

[0018] (d) The coefficient of dynamic friction of the surface of the insertion hole is 2.5 or less.

[0019] Effects of the Invention

[0020] The sealing member of the present invention is a cured product of a silicone rubber composition having silicone rubber and silica particles. By containing silica particles, the hardness of the sealing member can be easily adjusted, and the mechanical strength such as tensile strength can be easily improved. Furthermore, the sealing member of the present invention satisfies the above conditions (a) to (d). These four conditions are conditions determined for the purpose of suppressing the generation of incision damage discovered by the inventor of the present invention.

[0021] As specified in condition (a), in the sealing member of the present invention, the ratio of the elastic recovery rate to the content of the silica particles is 3.6 or more and 9.6 or less. The elastic recovery rate is the elastic deformation power η measured by the indentation test method. IT (%), the closer it is to 100%, the easier it is to elastically deform, in other words, it means that it is easy to recover to the original state even if deformed. The inventors of the present invention have obtained the following insights: the elastic recovery rate of the sealing member and the content of silica particles have a great influence on the incision damage caused when the other member is plugged in and out of the insertion hole of the sealing member, and the effective range for suppressing the incision damage is determined in the ratio of the two. For example, if only the elastic recovery rate is focused on, if its value is large, the restoring force for repeated deformation is large, so it is possible to become an indicator for suppressing incision damage. However, even if the elastic recovery rate is large, if the content of silica particles is small, the rubber itself becomes fragile, and therefore incision damage is easily generated. In this way, the generation of incision damage cannot be suppressed by only regulating either the elastic recovery rate or the content of silica particles. By satisfying condition (a), the elastic recovery rate and strength of the rubber (sealing member) can be taken into account. As a result, the residual strain caused by compression and stretching accompanying the plugging and unplugging of the other member is reduced, and the sealing member is not easily fatigued even if it is repeatedly plugged in and out.

[0022] As defined by condition (b), the seal member of the present invention has a type A durometer hardness of 15 or more and 30 or less. By satisfying condition (b), the hardness of the rubber (seal member) is optimized, and the occurrence of notch damage can be suppressed.

[0023] As specified in condition (c), the tensile strength at break of the sealing member of the present invention is 2.1 MPa or more. When condition (c) is satisfied, the intermolecular bonding of the rubber becomes strong, so the rubber molecules are not easily cut off by the mechanical load and thermal load applied when plugging and unplugging the other member. As a result, the mechanical strength of the rubber (sealing member) can be ensured, and the generation of incision damage can be suppressed.

[0024] As specified in condition (d), the coefficient of dynamic friction of the surface of the insertion hole of the sealing member of the present invention is less than 2.5. By satisfying condition (d), the friction of the surface of the insertion hole (the sliding contact surface with the other member) can be reduced. As a result, the mechanical load and thermal load applied when plugging and unplugging the other member are reduced, and the rubber molecules are not easily cut. As a result, the generation of incision damage can be suppressed.

[0025] As described above, the sealing member of the present invention satisfies conditions (a) to (d), and is less likely to be damaged by cuts in the insertion hole even when the counterpart member is repeatedly inserted and removed. Therefore, the sealing member of the present invention has excellent durability and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a front view of a gasket which is one embodiment of the sealing member of the present invention.

[0027] Figure 2 yes Figure 1 II-II sectional view.

[0028] Figure 3 It is an explanatory diagram of a method for evaluating the damage resistance of a gasket. DETAILED DESCRIPTION

[0029] First, as one embodiment of the sealing member of the present invention, a mode of using the sealing member as a gasket of a waterproof connector will be described. Figure 1 A front view of a gasket according to the present embodiment is shown. Figure 2 express Figure 1 II-II sectional view. Figure 1 , Figure 2 As shown, the sealing gasket 1 has a main body portion 10 and five insertion holes 20 .

[0030] The main body 10 is in the shape of a rectangular plate and is a cured product of a silicone rubber composition having terminal vinyl dimethyl polysiloxane (molecular weight 40,000), organohydrogen polysiloxane, silica particles, and phenyl-containing silicone oil. In the main body 10, the content of silica particles is 20 parts by mass relative to 100 parts by mass of terminal vinyl dimethyl polysiloxane, the value of "elastic recovery rate / content of silica particles" under condition (a) is 4.4, the A-type durometer hardness under condition (b) is 30, and the tensile strength at break under condition (c) is 4.4 MPa.

[0031] The five insertion holes 20 are respectively formed to penetrate in the thickness direction of the main body 10. The five insertion holes 20 respectively have an opening portion that is circular when viewed from the front surface, and are arranged in a row at equal intervals in the left-right direction. The distance D between adjacent insertion holes 20 is 2.6 mm. The five insertion holes 20 respectively have a lip portion 21 protruding inward. The lip portion 21 is annular, and two are arranged parallel to the thickness direction of the main body 10. An oil film (not shown) is arranged on the surface (inner circumferential surface) of the insertion hole 20. The oil film is formed by the phenyl-containing silicone oil that is a component of the silicone rubber composition seeping onto the surface of the insertion hole 20. The dynamic friction coefficient of the surface of the insertion hole 20 under condition (d) is 0.9. The shape, size, etc. of the five insertion holes 20 are all the same.

[0032] like Figure 2 As shown, the wires 8 with terminals are inserted into the five insertion holes 20 from the rear. The wires 8 with terminals have terminals 80 and wires 81. The terminal 80 is made of metal and is in the shape of a rectangular parallelepiped with a protrusion. The terminal 80 is mounted on the top end (front end) of the wire 81. The wires 8 with terminals are included in the concept of the counterpart member of the present invention.

[0033] The waterproof connector is mainly composed of a sealing gasket 1, an outer shell (connector shell) not shown in the figure, and an inner shell. The outer shell is box-shaped with a quadrilateral cylindrical side wall portion and a rear wall portion that blocks the rear end opening of the side wall portion, and five terminal insertion holes are formed in the rear wall portion for allowing the wires 8 with terminals to pass through. The sealing gasket 1 is arranged on the inner side of the rear wall portion of the outer shell, and the insertion hole 20 is arranged to correspond to the terminal insertion hole. The rear surface of the sealing gasket 1 is arranged to be in close contact with the rear wall portion of the outer shell. The inner shell is arranged to be in close contact with the front surface of the sealing gasket 1. The inner shell has a terminal accommodating portion for accommodating the terminal 80 that has passed through the insertion hole 20.

[0034] The wire 8 with the terminal is inserted from the terminal insertion hole of the outer housing into the insertion hole 20 of the sealing gasket 1. The terminal 80 advances forward while expanding the insertion hole 20, and is accommodated in the terminal accommodation portion of the inner housing after passing through the insertion hole 20. The lip 21 of the insertion hole 20 is in close contact with the outer periphery of the wire 81 extending backward from the terminal 80, thereby sealing the insertion hole 20 and the wire 81.

[0035] The sealing gasket 1 of this embodiment is a cured product of a silicone rubber composition having silicone rubber and silica particles, and satisfies four conditions (a) to (d). Therefore, in the sealing gasket 1, even if the terminal 80 is repeatedly inserted and removed, it is not easy to cause cut damage in the insertion hole 20. Therefore, the sealing gasket 1 has excellent durability and high reliability.

[0036] An embodiment of the sealing member of the present invention has been described above, but the sealing member of the present invention is not limited to this embodiment and can be implemented in various forms with changes and improvements that can be made by those skilled in the art within the scope of the present invention.

[0037] [Structure of sealing member]

[0038] The sealing member of the present invention has a plurality of insertion holes for inserting the counterpart member. The type, material, shape, size, etc. of the counterpart member are not particularly limited. For example, as in the terminal of the above-mentioned embodiment, when the counterpart member is made of metal and has a corner, it is easy to cause incision damage. Therefore, the sealing member of the present invention, which has a high effect of suppressing the generation of incision damage, is suitable for such a counterpart member.

[0039] The number of insertion holes is not particularly limited as long as it is more than two. The number of insertion holes, the configuration mode, the shape of the opening, the diameter of the opening, etc. can be appropriately determined according to the purpose of the sealing member, the number, material, shape, size, etc. of the other member. The insertion hole can be through in the thickness direction of the sealing member, or it can not be through. For example, in the case where the sealing member has a flat main body and a plurality of insertion holes are formed on the main body, if the distance between the insertion holes becomes closer, the insertion holes are likely to interfere with each other when the other member is plugged in or out. That is, when the other member is inserted into any insertion hole, the insertion hole adjacent to it is easily pressed and narrowed. In this case, when the other member is inserted into the adjacent insertion hole, incision damage is likely to occur. In this way, it can be expected that the more and denser the number of insertion holes becomes, the easier it is to produce incision damage. From the viewpoint of reducing the interference between the insertion holes, when the main body with the insertion holes is observed from the insertion direction of the other member, the distance between the adjacent insertion holes is preferably more than 1.3mm and less than 8.8mm. Here, the distance between adjacent insertion holes refers to the distance between the central axes of the adjacent insertion holes.

[0040] From the viewpoint of reducing the dynamic friction coefficient of the surface of the insertion hole, it is preferred that an oil film is arranged on at least a portion of the surface of the insertion hole. The oil film may be formed by the oil contained in the silicone rubber composition seeping out (oozing) onto the surface of the insertion hole, or by applying the oil on the surface of the insertion hole, or both. The oil forming the oil film will be described later.

[0041] [Composition and characteristics of sealing member]

[0042] The sealing member of the present invention is a cured product of a silicone rubber composition having silicone rubber and silicon dioxide particles. As the base polymer of the silicone rubber, a substance widely known as an organopolysiloxane can be used. The base polymer can be a liquid rubber or a solid (mixed) rubber. In terms of being able to be formed with good dimensional accuracy including the lip portion, liquid rubber is preferred.

[0043] Organopolysiloxane has a predetermined reactive group according to its crosslinking mechanism (curing mechanism). As reactive groups, alkenyl (vinyl, allyl, butenyl, pentenyl, hexenyl, etc.), silanol groups, etc. can be cited. The organopolysiloxane with the former alkenyl is crosslinked by a peroxide crosslinking reaction with an organic peroxide as a crosslinking agent, and by an addition reaction with an organopolysiloxane (organohydrogenpolysiloxane) with a hydrosilyl group (SiH group) as a crosslinking agent. In the addition reaction, hydrosilylation catalysts such as platinum catalysts can be used in combination. The organopolysiloxane with the latter silanol group is crosslinked by a condensation reaction. In the condensation reaction, a condensation crosslinking agent can be used in combination.

[0044] From the viewpoint of obtaining a cured product having good elasticity, it is preferred that the base polymer constituting the silicone rubber has an organopolysiloxane having at least two alkenyl groups in one molecule and the crosslinking agent has an organohydrogenpolysiloxane.

[0045] The organopolysiloxane has an organic group on the basis of the reactive group. The organic group is a monovalent substituted or unsubstituted hydrocarbon group. As the unsubstituted hydrocarbon group, alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl, aryl groups such as phenyl, aralkyl groups such as β-phenylethyl and β-phenylpropyl, etc. can be listed. As the substituted hydrocarbon group, chloromethyl, 3,3,3-trifluoropropyl, etc. can be listed. From the viewpoint of easy synthesis, an organopolysiloxane having a methyl group as an organic group is preferred. The organopolysiloxane is preferably a linear organopolysiloxane, and may also be a branched or cyclic organopolysiloxane.

[0046] The number of hydrosilyl groups possessed by the organohydrogenpolysiloxane of the crosslinking agent is not particularly limited, and is preferably 2 or more and 50 or less from the viewpoints of high curing speed and excellent stability. In this case, it is preferred that the hydrogen of the hydrosilyl group is bonded to different Si. The organohydrogenpolysiloxane may be a chain organohydrogenpolysiloxane or a cyclic organohydrogenpolysiloxane. As the organohydrogenpolysiloxane, methylhydrogenpolysiloxane terminated with trimethylsiloxy groups at both ends and dimethylsiloxane-methylhydrogensiloxane copolymers with trimethylsiloxy groups at both ends may be cited. The amount of the crosslinking agent may be set to be 0.1 or more and 40 or less parts by mass relative to 100 parts by mass of the organopolysiloxane having at least two alkenyl groups in one molecule.

[0047] The molecular weight of the base polymer of silicone rubber is not particularly limited. From the viewpoint of easily satisfying conditions (a) and (b), it is preferably 30,000 or more and 120,000 or less. More preferably, it is 33,000 or more and 100,000 or less. When the molecular weight is less than 30,000, the cured product (sealing member) becomes hard. Therefore, the stress generated when the other member is plugged in and out becomes larger, and incision damage is likely to occur. On the contrary, if the molecular weight exceeds 120,000, the length of the cross-linking point becomes longer and the elastic recovery rate becomes smaller. As a result, incision damage is likely to occur. In addition, in this specification, unless otherwise specified, the molecular weight refers to the weight average molecular weight.

[0048] In order to promote the cross-linking reaction of the base polymer, a catalyst can be appropriately coordinated. As the aforementioned hydrosilylation catalyst, platinum catalysts, ruthenium catalysts, rhodium catalysts, etc. can be listed. As the platinum catalyst, particulate platinum, platinum black, activated carbon loaded with platinum, silica loaded with platinum, chloroplatinic acid, alcohol solution of chloroplatinic acid, olefin complex of platinum, alkenyl siloxane complex of platinum, etc. can be listed. They can be used alone, or two or more can be used in combination.

[0049] As the silica particles, fumed silica, calcined silica, precipitated silica, etc. can be used. The silica particles can also be silica particles that have been subjected to surface treatment. For example, silica particles that have been subjected to hydrophobic treatment have excellent dispersibility in silicone rubber and are easy to ensure sufficient mechanical strength, which is preferred in this regard. The amount of silica particles can be appropriately adjusted in a manner that satisfies conditions (a) to (c). For example, it can be set to be 10 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of the base polymer. If the amount of silica particles is increased, the cured product (sealing member) becomes harder and the elastic recovery rate becomes smaller. On the contrary, if the amount of silica particles is reduced, the cured product becomes softer and the elastic recovery rate becomes larger. However, if the amount of silica particles is too small, the mechanical strength of the cured product is reduced.

[0050] As described above, from the viewpoint of reducing the coefficient of dynamic friction of the surface of the insertion hole, it is preferred that an oil film is disposed on at least a portion of the surface of the insertion hole. The oil film can be formed by allowing the oil as a component of the silicone rubber composition to seep out to the surface of the insertion hole, or it can be formed by applying oil to the surface of the insertion hole. In the former case, the silicone rubber composition preferably has an oil with low compatibility with silicone rubber. As oils with low compatibility with silicone rubber and easy to seep out, oils containing phenyl, ether-modified oils, liquid paraffin oils, etc. can be listed. One selected from them can be used or two or more can be mixed and used. Among them, from the viewpoint of easily controlling the timing of seepage from silicone rubber and being able to ensure good molding processability, oils containing phenyl are preferred. The amount of oil blended can be appropriately adjusted as long as it satisfies condition (d). For example, it can be set to be 0.5 mass parts or more and 15 mass parts or less relative to 100 mass parts of the base polymer. More preferably, it is 4 mass parts or more and 10 mass parts or less. In the latter case (when oil is applied to the surface of the insertion hole), the type of oil is not particularly limited, but the applied oil is preferably an oil that is difficult to penetrate into the silicone rubber and remains on the surface. From this point of view, as in the former case, it is preferred to use an oil with low compatibility with silicone rubber.

[0051] The silicone rubber composition may also contain additives other than the aforementioned materials as long as it satisfies conditions (a) to (d). Examples of additives include crosslinking accelerators, crosslinking delay agents, crosslinking aids, reinforcing materials, anti-aging agents, softeners, plasticizers, lubricants, heat stabilizers, flame retardants, flame retardant aids, ultraviolet absorbers, rust inhibitors, pigments, and the like.

[0052] The sealing member of the present invention satisfies the following four conditions (a) to (d).

[0053] (a) Elastic recovery rate (%) / X (mass parts) = 3.6 to 9.6

[0054] Elastic recovery rate is the elastic deformation power measured by the indentation test method. Elastic deformation power η IT (%) was calculated as follows: the load displacement curve was prepared by pressing the indenter into the surface of the test piece, and the plastic deformation work (W) was obtained from the load displacement curve. plast ) and the amount of work done by elastic deformation (W elast ), the total mechanical work is set as W total (=W plast +W elast ), calculated by the following formula (i).

[0055] η IT =W elast / W total ×100…(i)

[0056] In this specification, the calculated elastic deformation is referred to as power η IT The elastic recovery rate (%) is called the elastic recovery rate, and the elastic recovery rate (%) / X (mass parts) of the condition (a) is obtained by dividing the value of the elastic recovery rate by the content of the silica particles (X mass parts) per 100 mass parts of the base polymer.

[0057] When the elastic recovery rate is less than 3.6 relative to the content of the silica particles, the sealing member becomes hard and is difficult to return to its original state after deformation, so it is easy to be damaged by cutting. When it exceeds 9.6, the sealing member becomes soft and the mechanical strength is reduced, so it is easy to be damaged by cutting.

[0058] (b) Type A durometer hardness: 15 or more and 30 or less

[0059] The A-type durometer hardness can be measured by the method according to JIS K 6253-3: 2012. When the A-type durometer hardness is less than 15, the sealing member becomes soft and the mechanical strength decreases, so it is easy to cause incision damage. When it exceeds 30, the sealing member becomes hard and it is difficult to insert and remove the other member, so it is easy to cause incision damage.

[0060] (c) Tensile strength at break: 2.1 MPa or more

[0061] The tensile strength at break may be measured by a method in accordance with JIS K 6251: 2017. As a test piece, a dumbbell No. 3 is used. When the tensile strength at break is less than 2.1 MPa, the mechanical strength of the sealing member is reduced, and thus a notch damage is easily generated.

[0062] (d) Dynamic friction coefficient of the surface of the insertion hole: 2.5 or less

[0063] In this specification, the dynamic friction coefficient is a value measured using an automatic friction and wear analysis device ("Triboster 500" manufactured by Kyowa Interface Science Co., Ltd., a surface contact). The measurement conditions are set to a load of 100 gf (0.98 N) and a tensile speed of 500 mm / min. If the dynamic friction coefficient exceeds 2.5, the friction of the surface of the insertion hole (the sliding contact surface with the other member) becomes large, and incision damage is likely to occur. The dynamic friction coefficient of the surface of the insertion hole is more preferably less than 2.0.

[0064] [Method for manufacturing sealing member]

[0065] The sealing member of the present invention can be manufactured by curing a silicone rubber composition having silicone rubber and silica particles. For example, an injection molding machine is used to inject the silicone rubber composition into a mold and heat it to cure it. The heating temperature can be set to about 140 to 170° C., and the curing time can be set to about 5 to 10 minutes.

[0066] Example

[0067] Next, the present invention will be described in more detail with reference to examples.

[0068] (1) Characteristics of sealing components

[0069] <Manufacturing of Test Specimens>

[0070] First, various silicone rubber compositions are prepared by mixing the predetermined raw materials in the amounts shown in Tables 1 and 2 described later using a planetary mixer. Next, the prepared silicone rubber composition is press-formed at a temperature of 170°C for 10 minutes, thereby curing and manufacturing test pieces corresponding to the method for measuring the properties described later. The test pieces of Examples 1 to 10 shown in Table 1 are included in the concept of the sealing component of the present invention. The details of the raw materials used are as follows.

[0071] [Base rubber]

[0072] Terminal vinyl dimethyl polysiloxane A: "Polymer VS2000" manufactured by EVONIK Co., Ltd., molecular weight: 25,000.

[0073] Terminal vinyl dimethyl polysiloxane B: "Polymer VS5000" manufactured by EVONIK Co., Ltd., molecular weight 33,000.

[0074] Terminal vinyl dimethyl polysiloxane C: "Polymer VS10000" manufactured by EVONIK Co., Ltd., molecular weight 40,000.

[0075] Terminal vinyl dimethyl polysiloxane D: "Polymer VS20000" manufactured by EVONIK Co., Ltd., molecular weight 50,000.

[0076] Terminal vinyl dimethyl polysiloxane E: "Polymer VS65000" manufactured by EVONIK Co., Ltd., molecular weight 67,000.

[0077] Terminal vinyl dimethyl polysiloxane F: "Polymer VS100000" manufactured by EVONIK Co., Ltd., molecular weight: 100,000.

[0078] Terminal vinyl dimethyl polysiloxane G: "Polymer VS165000" manufactured by EVONIK Co., Ltd., molecular weight: 130,000.

[0079] Side chain vinyl dimethyl polysiloxane H: molecular weight is 500,000.

[0080] Terminal vinyl dimethyl polysiloxane I: molecular weight 480,000.

[0081] Terminal-side chain vinyl dimethyl polysiloxane J: molecular weight 500,000.

[0082] H to J in the above-mentioned vinyl-containing dimethylpolysiloxane were synthesized as follows.

[0083] (1) Side chain vinyl dimethyl polysiloxane H

[0084] First, add 74.7g of octamethylcyclotetrasiloxane, 0.086g of 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane and 0.1g of potassium silicate into a container replaced with argon, and stir at 120°C for 30 minutes. Then raise the temperature to 155°C, continue stirring for 3 hours, add 0.1g of hexamethyldisiloxane, and stir at 155°C for 4 hours. After the reaction is completed, dilute with toluene and wash with water 3 times. The washed organic layer is washed several times with methanol, thereby reprecipitating and purifying to separate oligomers and polymers. The obtained polymer is dried under reduced pressure at 60°C overnight to obtain side chain vinyl dimethyl polysiloxane H.

[0085] (2) Terminal vinyl dimethyl polysiloxane I

[0086] In the synthesis method of the side chain vinyldimethylpolysiloxane H of (1), except that 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was not used and 0.1 g of 1,3-divinyltetramethyldisiloxane was added instead of hexamethyldisiloxane, a terminal vinyldimethylpolysiloxane I was obtained in the same manner as in the synthesis method of (1).

[0087] (3) Terminal-side chain vinyl dimethyl polysiloxane J

[0088] In the synthesis method of side chain vinyldimethylpolysiloxane H of (1), except that the amount of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was changed to 0.86 g and 0.1 g of 1,3-divinyltetramethyldisiloxane was added instead of hexamethyldisiloxane, the same operation as the synthesis method of (1) was carried out to obtain terminal-side chain vinyldimethylpolysiloxane J.

[0089] [Crosslinking agent]

[0090] Organohydrogenpolysiloxane A: "KF-9901" manufactured by Shin-Etsu Chemical Co., Ltd.

[0091] Organohydrogenpolysiloxane B: "TC-25D" manufactured by Momentive Corporation.

[0092] [Silicon dioxide particles]

[0093] Silica particles: hydrophobic fumed silica surface-treated with hexamethyldisilazane, “AEROSIL (registered trademark) RX200” manufactured by Nippon AEROSIL Co., Ltd.

[0094] [Oil]

[0095] Phenyl-containing silicone oil: "KF-53" manufactured by Shin-Etsu Chemical Co., Ltd.

[0096] Ether-modified silicone oil: "KF-354L" manufactured by Shin-Etsu Chemical Co., Ltd.

[0097] Liquid paraffin oil: "Liquid paraffin" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0098] [catalyst]

[0099] Platinum hydrosilylation catalyst A: "Pt-VTSC-3.0X" manufactured by Umicore Japan Co., Ltd.

[0100] Hydrosilylation platinum catalyst B: "TC-25A" manufactured by Momentive Corporation.

[0101] <Methods of measuring properties>

[0102] Using the produced test pieces, the elastic recovery rate, type A durometer hardness, and dynamic friction coefficient of the cured product of the silicone rubber composition were measured. Each measurement method is described below.

[0103] [Elastic recovery rate]

[0104] Using a micro-hardness tester based on the indentation test method ("FISCHERSCOPE (registered trademark) H100C" manufactured by Fischer Instruments), the indenter was pressed into the surface of a square-shaped test piece under the following measurement conditions to produce a load-displacement curve. The size of the test piece is 30 mm long on one side and 2 mm thick. The amount of work done by plastic deformation (W) was calculated from the obtained load-displacement curve. plast ) and the amount of work done by elastic deformation (W elast ), the total mechanical work is set as W total (=W plast +W elast ), the elastic deformation power η is calculated from the above formula (i) IT (%) The calculated elastic deformation power η ITThe elastic recovery rate (%) was taken as the elastic recovery rate, and the value was divided by the content of the silica particles (X parts by mass) relative to 100 parts by mass of the base polymer to determine "elastic recovery rate (%) / X (parts by mass)" of the condition (a).

[0105] Measurement conditions

[0106] Indenter: A four-sided pyramid diamond indenter with an opposing angle of 136°.

[0107] Initial load: 0mN.

[0108] Maximum pressing load: 10mN (constant load).

[0109] Maximum load arrival time: 3 sec.

[0110] Maximum load holding time: 5 sec.

[0111] Unloading time: 3sec.

[0112] Measurement temperature: 25℃.

[0113] [Type A Durometer Hardness]

[0114] The type A durometer hardness of a test piece having a thickness of 12 mm was measured by a method in accordance with JIS K 6253-3:2012.

[0115] [Tensile strength at break]

[0116] The tensile strength at break of dumbbell No. 3 (thickness 2 mm) was measured by the method according to JIS K 6251:2017. b (MPa) was measured.

[0117] [Dynamic friction coefficient]

[0118] The dynamic friction coefficient of the surface of a square sheet test piece with a thickness of 2 mm and a square shape of 30 mm was measured using an automatic friction and wear analyzer ("Triboster 500" manufactured by Kyowa Interface Science Co., Ltd., surface contact). The measurement conditions were set to a load of 100 gf (0.98 N) and a tensile speed of 500 mm / min. In addition, in Table 1, for the test pieces of Examples 2, 4, 5, and 7 recorded as "applied" in the oil column, oil was applied to the surface of the test piece for measurement.

[0119] <Measurement Results of Characteristics>

[0120] Tables 1 and 2 collectively show the raw materials used in the production of the test pieces and the measurement results of the properties.

[0121]

[0122]

[0123] As shown in Table 1, the cured products of Examples 1 to 10 satisfy all four conditions (a) to (d). On the other hand, as shown in Table 2, the cured products of Comparative Examples 1 to 9, which are different from Examples 1 to 10 in terms of molecular weight of base polymer, amount of silica particles, presence or absence of oil, etc., do not satisfy the four conditions (a) to (d). For example, the cured product of Comparative Example 1 has a smaller molecular weight of base polymer than the cured product of Example 8. As a result, the A-type durometer hardness increases. The cured product of Comparative Example 2 has a larger molecular weight of base polymer than the cured products of Examples 3, 9, and 10. As a result, the ratio of elastic recovery rate to the content of silica particles decreases. The cured product of Comparative Example 3 has a lower content of silica particles than the cured product of Example 3. As a result, the ratio of elastic recovery rate to the content of silica particles increases, and the A-type durometer hardness and tensile strength at break decrease. On the contrary, the cured product of Comparative Example 5 has a higher content of silica particles than the cured product of Example 3. As a result, the ratio of the elastic recovery rate to the content of the silica particles becomes smaller, and the A-type durometer hardness becomes larger. The content of silica particles in the cured product of Comparative Example 4 is less than that in the cured product of Example 6. As a result, the ratio of the elastic recovery rate to the content of the silica particles becomes larger, and the tensile strength at break becomes smaller. The cured product of Comparative Example 6 does not have an oil film on the surface. As a result, the dynamic friction coefficient of the surface becomes larger than that of the cured products of Examples 3 to 5. The molecular weight of the base polymer of the cured products of Comparative Examples 7 to 9 is large, and there is no oil film on the surface. Therefore, the dynamic friction coefficient of the surface becomes larger, and in the cured products of Comparative Examples 8 and 9, the A-type durometer hardness becomes larger, and in the cured product of Comparative Example 9, the ratio of the elastic recovery rate to the content of the silica particles also becomes smaller.

[0124] <Evaluation of Damage Resistance of Sealing Member>

[0125] In the same manner as in the preparation of the aforementioned test piece, various silicone rubber compositions were prepared according to the formulations shown in Tables 1 and 2, and stamped to produce the sealing gasket 1 of the above embodiment (see the above Figure 1 , Figure 2 ). In Table 1, for the gaskets of Examples 2, 4, 5, and 7 which are recorded as "applied" in the oil column, oil is applied to the surface (inner peripheral surface) of the insertion hole of the manufactured gasket. The gaskets of Examples 1 to 10 shown in Table 1 are included in the concept of the sealing component of the present invention. The manufactured gasket is set in the housing, the terminal is plugged in and out, and the difficulty of causing cut damage (damage resistance) is evaluated. The evaluation method is as follows. Figure 3 An explanatory diagram showing a method for evaluating the damage resistance of a gasket. Figure 3 With the above Figure 1 correspond.

[0126] like Figure 3 As shown in FIG. 1 , the five insertion holes 20 formed in the sealing gasket 1 are numbered No. 1 to No. 5 in sequence from the left. Then, first, the terminals of the wires with terminals are inserted in the order of No. 1 to No. 5, and then the wires are pulled out in the order of No. 5 to No. 1. After repeating this operation three times, as shown in FIG. Figure 3 As shown by the dashed lines in FIG. 1 , the insertion hole 20 portion of the gasket 1 was cut in the left-right direction, and the number of cut damages generated on the surfaces (inner peripheral surfaces) of the five insertion holes 20 was counted.

[0127] The results are summarized in the above-mentioned Tables 1 and 2. As shown in Table 1, the number of incision damages in the gaskets of Examples 1 to 10 that satisfy all four conditions (a) to (d) is 20 or less, whereas the number of incision damages in the gaskets of Comparative Examples 1 to 9 that do not satisfy any of the conditions (a) to (d) is greater than 20. Based on the above, it is confirmed that in the sealing member of the present invention, it is not easy to generate incision damage in the insertion hole due to the insertion and removal of the counterpart member.

[0128] Industrial Applicability

[0129] The sealing member of the present invention can be applied to various parts in the automotive field, industrial equipment field, information communication equipment field, etc. In particular, it is suitable for multi-pole rubber plugs, multi-hole rubber bushings, multi-hole wire sheaths, etc. of waterproof connectors.

[0130] Description of Reference Numerals

[0131] 1: Sealing pad (sealing member); 10: Main body; 20: Insertion hole; 21: Lip; 8: Wire with terminal (counterpart member); 80: Terminal; 81: Wire.

Claims

1. A sealing member having a plurality of insertion holes for inserting a counterpart member, characterized in that: The sealing member is a cured product of a silicone rubber composition having silicone rubber and silica particles, and satisfies the following conditions (a) to (d): (a) when the content of the silica particles relative to 100 parts by mass of the base polymer of the silicone rubber is X parts by mass, elastic recovery rate (%) / X (parts by mass) = 3.6 to 9.6; (b) A-type durometer hardness of 15 or more and 30 or less; (c) a tensile strength at break of 2.1 MPa or more; (d) The coefficient of dynamic friction of the surface of the insertion hole is 2.5 or less.

2. The sealing member according to claim 1, characterized in that The base polymer of the silicone rubber has an organopolysiloxane having at least two alkenyl groups in one molecule, The silicone rubber composition has a crosslinking agent, and the crosslinking agent has a SiH group.

3. The sealing member according to claim 1 or 2, characterized in that: The sealing member has an oil film disposed on at least a portion of a surface of the insertion hole.

4. The sealing member according to claim 3, characterized in that The silicone rubber composition has oil, The oil film is formed when the oil seeps out onto the surface of the insertion hole.

5. The sealing member according to claim 3, characterized in that The oil film is formed by applying oil to the surface of the insertion hole.

6. The sealing member according to claim 4, characterized in that The oil is at least one selected from phenyl-containing oil, ether-modified oil, and liquid paraffin oil.

7. The sealing member according to claim 1 or 2, characterized in that: The molecular weight of the base polymer of the silicone rubber is 33,000 or more and 100,000 or less.

8. The sealing member according to claim 1 or 2, characterized in that: The sealing member has a flat plate-shaped main body, and the plurality of insertion holes are formed to penetrate the main body in a thickness direction. When the main body is viewed from the insertion direction of the counterpart member, the distance between adjacent insertion holes is not less than 1.3 mm and not more than 8.8 mm.

9. The sealing member according to claim 1 or 2, characterized in that: The counterpart member is made of metal and has a corner portion.

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