JP2012183784A - Elastomer with discontinuous metal coating and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastomer with a discontinuous metal coating in which the discontinuous metal coating provided on the surface of a substrate formed of silicone rubber is hard to be peeled off from the substrate and also hard to be cracked.SOLUTION: The elastomer with the discontinuous metal coating includes steps for: laminating a primer coating layer 13 comprising a chlorinated polyolefin resin, an undercoat layer 15 comprising an acrylic resin or a polyurethane resin, a discontinuous metal coating 21 formed by vapor deposition and a top coat layer 25 on a silicone substrate 11 formed by peroxide crosslinking and having a D4 to D10 low molecular weight siloxane content of 300 PPM or smaller in this order; and making the top coat layer 25 by the same material as the undercoat layer 15.

Description

  The present invention relates to an elastic body in which a discontinuous metal coating is provided on a base material made of silicone rubber, and a method for producing the same.

  Silicone rubber has elasticity and is excellent in heat resistance, cold resistance, and chemical stability, and is therefore widely used in applications that require these functions. Moreover, depending on the use of silicone rubber, a metal coating may be required on the surface.

  However, when a metal film is formed on the surface of the silicone rubber by a normal metal film forming method such as vapor deposition, the metal film may be peeled off due to the tension or bending of the silicone rubber, or the metal film may be cracked. is there.

  In addition, as a method for preventing the peeling and cracking of the metal film, a metal thin film layer having a grain boundary of 150 to 800 mm is formed on a base material made of a soft resin material (Patent Document 1), or metal particles After the thin film layer is formed on the surface of the base material, the entire base material is thermally expanded to generate fine groove-like cracks in the metal particle layer (Patent Document 2). Metal thin film layer having a flat surface structure in which a large number of island parts made of vapor-deposited metal grains having a maximum length in the longitudinal direction of 5 μm or less are concentrated discontinuously and having a layer thickness of 20 nm to 100 nm There is a method (Patent Document 3) for forming a silicone rubber.

JP-A-11-34220 JP-A-11-131213 Japanese Patent Laid-Open No. 2007-136689

However, the conventional method for preventing peeling or cracking of the metal coating has not been sufficient to prevent peeling or cracking of the metal coating.
This invention is made | formed in view of the said point, Comprising: It aims at provision of the elastic body which has a discontinuous metal film which is hard to produce peeling and a crack of a metal film, and its manufacturing method.

  The invention according to claim 1 is a primer coat layer made of a chlorinated polyolefin resin and an acrylic resin on a silicone substrate formed by peroxide crosslinking and having a content of low molecular siloxanes of D4 to D10 of 300 PPM or less. Alternatively, an undercoat layer made of a polyurethane resin, a discontinuous metal film formed by vapor deposition, and a topcoat layer are laminated in this order, and the topcoat layer is made of the same material as the undercoat layer. The present invention relates to an elastic body having a discontinuous metal coating.

Invention of Claim 2 is a manufacturing method of the elastic body which has a discontinuous metal film vapor-deposited on the base material which consists of silicone rubber formed by peroxide bridge | crosslinking, Comprising: The said base material is 180-200 degreeC, and is 1 After heat treatment for 12 hours, the surface of the base material is subjected to a surface treatment selected from the group of flame treatment, corona discharge treatment, and plasma treatment, and the surface of the base material is made of a chlorinated polyolefin resin. A layer and an undercoat layer are formed in order, a discontinuous metal film is formed by vapor deposition, and a topcoat layer made of the same material as the undercoat layer is formed on the discontinuous metal film. The present invention relates to a method for producing an elastic body having a discontinuous metal coating.

The invention of claim 3 is characterized in that, in claim 2, the primer coat layer is made of a chlorinated polyolefin resin, and the undercoat layer and the top coat layer are made of an acrylic resin or a polyurethane resin.

  According to the present invention, a discontinuous metal film formed by vapor deposition is sandwiched between a top coat layer and an undercoat layer made of the same material, so that the discontinuous metal film is hardly peeled off even by bending of an elastic body. It becomes hard to produce a crack with becoming. Furthermore, according to the production method of the present invention, the metal film is formed by vapor deposition after heating the base material made of silicone rubber formed by peroxide crosslinking at 180 to 200 ° C. for 1 to 12 hours. The content of the low molecular siloxanes of D4 to D10 contained in is less than or equal to 300 PPM, and the manufactured metal film is difficult to be peeled and cracked even by bending of the elastic body. The “discontinuous metal coating” in the present invention is a metal coating that is not continuous on one side, and a large number of vapor-deposited metal particles having a maximum length in the plane direction of 10 μm or less are separated from each other in an island shape or partially. It is the meaning of the metal film which forms the planar shape in the state which contacted.

It is an expanded sectional view of the elastic body which has the discontinuous metal film manufactured with the manufacturing method of this invention.

  An elastic body 10 having a discontinuous metal film shown in FIG. 1 is manufactured by the method for manufacturing an elastic body having a discontinuous metal film according to the present invention. The undercoat layer 15, the discontinuous metal coating 21, and the topcoat layer 25 are sequentially formed.

  The substrate 11 is made of silicone rubber. The silicone rubber is formed by peroxide crosslinking, and the content of the low molecular siloxane of D4 to D10 becomes 300 PPM or less by heat treatment, so that the adhesion with the primer coat layer 13 can be improved. It is preferable. The thickness of the base material 11 is determined according to the use of the elastic body 10 having the metal coating.

  The primer coat layer 13 is provided to satisfactorily form the metal coating 21 by vapor deposition, and is made of a polyolefin resin, a chlorinated polyolefin resin, an epoxy resin, an acrylic resin, a polyester resin, a polyurethane resin, or the like. Become. A chlorinated polyolefin resin excellent in weather resistance, acid resistance and alkali resistance is preferable. In consideration of compatibility with the undercoat layer, a resin modified with a compound having a polar group such as epoxy or maleic anhydride is further added. preferable. The primer coat layer 13 preferably has a thickness of 2 to 4 μm.

  The undercoat layer 15 is provided on the surface of the primer coat layer 13 in order to satisfactorily form the metal coating 21 by vapor deposition, and is made of an epoxy resin, an acrylic resin, a polyester resin, a polyurethane resin, or the like. When a chlorinated polyolefin resin is used for the primer coat layer, a polyurethane resin or an acrylic resin is preferable. The thickness of the undercoat layer 15 is preferably 10 to 12 μm.

  The discontinuous metal coating 21 is provided for imparting a metallic tone to the substrate 11. The thickness of the metal coating 21 is preferably 400 to 1000 mm. Examples of the metal constituting the metal coating 21 include aluminum, chromium, copper, silver, gold, germanium, indium, iron, magnesium, nickel, tin, and zinc. Among these, aluminum, indium, magnesium and the like are preferable.

  The top coat layer 25 is provided for protecting the surface of the discontinuous metal coating 21, and is made of an epoxy resin, an acrylic resin, a polyester resin, a polyurethane resin, or the like. The thickness of the top coat layer 25 is preferably 10 to 12 μm. Since the top coat layer 25 passes through the discontinuous metal film 21 and adheres to the undercoat layer 15 to sandwich the discontinuous metal film 21, the top coat layer 25 is preferably made of the same resin as the undercoat layer 15. .

Next, the manufacturing method of the elastic body 10 which has the said discontinuous metal film is demonstrated.
First, the base material 11 made of silicone rubber is heated. In the production of silicone rubber, a material to which a silicone polymer, a peroxide vulcanizing agent and, if necessary, an additive such as a pigment are added is kneaded with an open roll. After kneading, sheeting is performed to an appropriate thickness, and vulcanization is performed by a hot press at an appropriate molding temperature and pressure to perform molding.

  The substrate 11 is heated to forcibly remove unreacted substances such as low-molecular siloxane and silicone oil contained in the silicone rubber constituting the substrate 11 from the substrate 11. If a large amount of unreacted substances such as low molecular weight siloxane and silicone oil are present on the surface or inside of the base material 11, the adhesion between the primer coat layer 13 and the base material 11 formed thereafter deteriorates. The metal film 21 is easily peeled off from the base material 11 and the metal film 21 is easily cracked. The difference in the difficulty of peeling and cracking of the metal coating 21 between the case where the heating is not performed and the case where the heating is performed is small immediately after the production of the elastic body 10 having the metal coating, The longer the period after manufacture, the larger the period.

  The heating temperature is preferably 180 to 200 ° C. When the heating temperature is lower than 180 ° C., unreacted substances such as low molecular siloxane and silicone oil cannot be sufficiently removed from the silicone rubber, and the effect of preventing the metal film 21 from peeling and cracking is reduced. On the other hand, when the heating temperature is higher than 200 ° C., the silicone rubber is easily deformed by heating. The heating time is preferably 1 to 12 hours. Especially preferably, it is 2 to 6 hours. Heating shorter than 1 hour cannot sufficiently remove unreacted substances such as low-molecular siloxane and silicone oil from the silicone rubber, and the content of low-molecular siloxanes D4 to D10 is greater than 300 PPM, resulting in decreased adhesion. . On the other hand, when the heating is longer than 12 hours, the production efficiency is deteriorated.

  After the substrate 11 is heated, a surface treatment selected from the group of flame treatment, corona discharge treatment, and plasma treatment is performed. For example, the flame treatment is a method of improving the adhesion by baking the surface of the base material 11 with a gas burner. Generally, the surface of the base material 11 having a low polarity is blown with a gas flame to The molecules on the surface of 11 can be polar and the wettability can be improved. Also, the corona discharge treatment or plasma treatment that generates a base having a polarity on the surface of the substrate 11 can improve the adhesion as in the frame treatment.

  After the surface treatment, a primer coat layer 13 and an undercoat layer 15 are sequentially formed on the surface of the substrate 11 with a predetermined thickness. The primer coat layer 13 and the undercoat layer 15 are formed by a known coating method such as spray coating. The primer coat layer 13 and the undercoat layer 15 are each dried and cured after application.

  Next, the discontinuous metal film 21 is formed on the surface of the undercoat layer 15 by vapor deposition. The said vapor deposition is performed by a well-known method. In particular, physical vapor deposition such as sputtering is preferable. The vapor deposition is performed so that the metal coating 21 has a predetermined thickness, preferably 400 to 1000 mm.

  After the metal coating 21 is formed, the top coat layer 25 is formed on the surface of the metal coating 21 with a predetermined thickness. The top coat layer 25 is formed by spray coating or the like. Thereby, the elastic body 10 having the metal film is obtained.

  Grade: TSE-221-5UC, Momentive Performance Materials, 100 parts by weight, Grade: TC-8, Momentive Performance Materials, 5 parts by weight silicone rubber (formed by peroxide crosslinking) And a base material made of a square plate having a thickness of 2 mm and a side of 100 mm was prepared.

  The base material was accommodated in a thermostatic layer, and the base material was heated at the heating temperature and heating time shown in Table 1. Then, the said base material was taken out from the thermostat, naturally cooled, and the amount of low molecular siloxane was measured. In addition, 0.5 g of silicone rubber sample pieces were immersed in 5 ml of acetone for 12 hours, and 1 μl was measured with a gas chromatograph (Shimadzu GC-17A). The total amount of the body and the non-cyclic body (D4 to D10) was quantified as the amount of low molecular siloxane. Flame treatment was performed by applying a flame of a gas burner to one side of the cooled substrate. Next, the primer coating was spray-coated on one side of the base material after the frame treatment, and then dried at 70 ° C. for 3 minutes to form a primer coating layer having a thickness of 3 μm on the surface of the base material. The primer paint used was a primer for polypropylene, product number: S-No. 54 PP primer no. 2 (chlorinated polyolefin resin), Nagashima Special Paint Co., Ltd.

  Undercoat was spray-coated on the surface of the primer coat layer, followed by preheating at 70 ° C. for 3 minutes, followed by drying at 80 ° C. for 120 minutes to form an undercoat layer having a thickness of 11 μm. The composition of the under paint used is: paint solution of acrylic resin paint, part number: Origin Plate Z Clear, Origin Electric Co., Ltd., 400 parts by weight, curing agent for acrylic resin paint, part number: Polyhard R, Origin Electric Co., Ltd. ), 100 parts by weight, thinner of acrylic resin paint, product number: Planet Thinner # D210, Origin Electric Co., Ltd., 300 parts by weight.

The base material after forming the primer coat layer and the undercoat layer is accommodated in a vacuum deposition apparatus, indium, purity 99.99%, length 45 mm, degree of vacuum 3.0 × 10 ⁻² Pa, residual heat 1 1100 A / 15 A, Deposition was performed with residual heat 2 1200A / 15A and vapor deposition 1350A / 15A, and a discontinuous metal film having a thickness of 600 mm was formed on the surface of the undercoat layer.

  Next, a top coating is spray-coated on the surface of the discontinuous metal coating, followed by preheating at 70 ° C. for 3 minutes, followed by drying at 70 ° C. for 120 minutes to form a topcoat layer having a thickness of 11 μm. The elastic body which has a metal film of Examples 1-5 was manufactured. The top paint used is the same as the under paint. Acrylic resin paint liquid, part number: Origin Plate Z Clear, Origin Electric Co., Ltd., 400 parts by weight, acrylic resin paint curing agent, part number: Polyhard R, Origin Electric Co., Ltd., 100 parts by weight, acrylic resin paint thinner, product number: Planet Thinner # D210, Origin Electric Co., Ltd., 300 parts by weight, slip agent, product number: 4001, Toho Kaken Kogyo Co., Ltd. 24 parts by weight.

  On the other hand, the same silicone rubber as in the above example was used, and heating was not performed before the metal coating was formed, so the content of low molecular siloxanes D4 to D10 was 5300, and the same silicone as in the above example. Comparative Example 2 in which the content of the low molecular siloxane of D4 to D10 was 1700 because the heating temperature was set to 150 ° C. and the heating time was set to 3 hours using rubber. Comparative Example 3 in which the content of low molecular siloxanes of D4 to D10 was 330 because the heating time was set to 180 ° C. and the heating time was 0.5 hours, except that an addition reaction type silicone (RTV) rubber using a platinum catalyst was used. The elastic bodies having the discontinuous metal coating of Comparative Example 4 performed in the same manner as in Example 5 were produced.

About each Example and each comparative example, the presence or absence of a deformation | transformation and discoloration, the cross-cut test immediately after manufacture, the cross-cut test after 2 months storage, the tensile test immediately after manufacture, and the tensile test after 2 months storage were done.
The presence / absence of deformation / discoloration is determined by visual observation of whether the base material is discolored (color loss) or distortion occurs in each of the Examples and Comparative Examples after production, and there is no discoloration or deformation. “None” in the case, and “Yes” in either case.

In the cross cut test immediately after the manufacture, the surface of the top coat layer in each of the examples and the comparative examples immediately after the manufacture is cut with a 100 cut grid pattern at intervals of 1.5 mm, and the cellophane tape is adhered to the top of the 100 coat. The number of wrinkles that were peeled off and the topcoat layer was not peeled was counted.
The cross cut test after storage for 2 months was carried out after the production of each Example and each Comparative Example and after storage in the room (room temperature storage) for 2 months, on the surface of the topcoat layer in each Example and each Comparative Example. 100 mm grid-like cuts were made at intervals of 5 mm, and the cellophane tape was adhered and peeled onto 100 mm, and the number of wrinkles on which the topcoat layer did not peel was counted.

In the tensile test immediately after production, whether the primer coat layer, the undercoat layer, the metal coating, and the top coat layer were peeled off from the substrate by performing a tensile test by autograph for each example and each comparative example immediately after production. It was judged visually.
The tensile test after storage for 2 months was conducted after each example and each comparative example was manufactured and stored indoors (stored at room temperature) for 2 months, and then for each example and each comparative example, an autograph tensile test (JIS K6251 Dumbbell No. 3) was performed so that the elongation was 100%, and it was visually determined whether or not the primer coat layer, the undercoat layer, the metal coating, and the top coat layer were peeled off from the substrate.

  The results are shown in Table 1. As shown in Table 1, in Examples 1 to 8, the cross-cut test result was 100/100 immediately after production and after storage for 2 months, and the tensile test result was not peeled off. . Further, none of Examples 1 to 8 was deformed or discolored.

  On the other hand, in Comparative Example 1 in which the content of the low molecular siloxanes D4 to D10 is high because no heating is performed, the cross-cut test result immediately after manufacture is 100/100, and the tensile test result immediately after manufacture is not peeled off. It can be seen that the cross-cut test result after storage for 2 months is 50/100, the tensile test result after storage for 2 months is peeled off, and the metal film is easily peeled off after a long period of time. Moreover, since the heating temperature is as low as 150 ° C., Comparative Example 2 in which the content of the low molecular siloxane of D4 to D10 is high is 100/100 for the cross-cut test result immediately after manufacture, and the tensile test result immediately after manufacture is not peeled off. However, it was found that the cross-cut test result after storage for 2 months was 90/100 and the tensile test result after storage for 2 months was peeled off, and the metal film was easily peeled off after a long period of time. Further, Comparative Example 3 having a heating temperature as short as 0.5 hours and a high content of low molecular weight siloxane of D4 to D10 has a cross-cut test result immediately after manufacture of 100/100, and a tensile test result immediately after manufacture does not peel off. However, it was found that the cross-cut test result after storage for 2 months was 90/100 and the tensile test result after storage for 2 months was peeled off, and the metal film was easily peeled off after a long period of time. In addition, Comparative Example 4 was an addition reaction type silicone (RTV) using a platinum catalyst, and vapor deposition was performed under the same conditions as in Example 5. However, the cross-cut test result immediately after production was 50/100.

  Moreover, in order to confirm the difference in the difficulty of peeling of the discontinuous metal film depending on the type of the primer coat layer, a comparison was made in which the primer paint was replaced with an acrylic resin paint instead of the primer paint of the chlorinated polyolefin resin in Example 2. The elastic body having the discontinuous metal coating of Example 5 and the elastic body having the discontinuous metal coating of Comparative Example 6 in which the primer coating was made of polyurethane resin were produced under the same conditions as in Example 2, and immediately after the production. A cross-cut test was conducted.

  The results are as shown in Table 2. In Example 2 in which the primer paint was a chlorinated polyolefin resin, 100% of the primer was not peeled off (100/100), whereas the primer paint was an acrylic resin. Comparative Example 5 in which the coating material was used and Comparative Example 6 in which the primer coating material was used as the polyurethane-based resin both resulted in 100% peeling of 100% (100/100). From this, it can be seen that, in the present invention, using a chlorinated polyolefin resin as the primer coat layer is effective in making it difficult to peel off the discontinuous metal film.

  In the present invention, the reason why the adhesion (difficult to peel off) with the discontinuous metal film by the silicone rubber by peroxide crosslinking is good is not clear, but it is thought to be due to the peroxide residue in the rubber. The side chain of the silicone before cross-linking consists of a methyl group, a vinyl group, etc., and the vinyl group is contained in an amount of about 2 to 30%. In the case of the cross-linking, radicals are not consumed, and if the temperature drops after cross-linking, the peroxide returns to the peroxide, so it is considered that the peroxide remains in the rubber. By subjecting the peroxide residue to flame treatment etc., the peroxide is decomposed again to generate radicals, and by applying a chlorinated polyolefin resin primer in that state, the silicone surface methyl group, vinyl group, etc., It is considered that the hydrocarbon chains and hydrocarbon groups in the premer are cross-linked and the adhesion is improved. That is, it is considered that the adhesion is further improved by the effect of cross-linking the silicone and the primer by generating radicals in the silicone while generating the surface polarity by frame treatment or the like.

As described above, the product of the present invention is such that the metal coating is difficult to peel off from the base material, has no discoloration or deformation, and has a good metallic appearance. For example, an automobile interior, exterior member, switch, center panel It is suitable for surrounding decorative parts, cushion members and the like.
In addition, in the said Example, although the metal film was formed only on the single side | surface of a base material, you may form a metal film on both surfaces of a base material.

DESCRIPTION OF SYMBOLS 10 Elastic body which has metal film 11 Base material 13 Primer coat layer 15 Undercoat layer 21 Discontinuous metal film 25 Topcoat layer

Claims (3)

  A primer coat layer made of a chlorinated polyolefin resin and an undercoat made of an acrylic resin or a polyurethane resin on a silicone substrate formed by peroxide crosslinking and having a content of low molecular siloxanes of D4 to D10 of 300 PPM or less A discontinuous metal coating comprising: a coat layer; a discontinuous metal film formed by vapor deposition; and a top coat layer laminated in this order; and the top coat layer is made of the same material as the undercoat layer. Elastic body having. A method for producing an elastic body having a discontinuous metal film deposited on a base material made of silicone rubber formed by peroxide crosslinking, wherein the base material is heated at 180 to 200 ° C for 1 to 12 hours. The substrate surface is subjected to a surface treatment selected from the group of flame treatment, corona discharge treatment and plasma treatment, and a primer coat layer and an undercoat layer made of a chlorinated polyolefin resin are sequentially applied to the surface of the substrate. After forming, a discontinuous metal film is formed by vapor deposition, and a topcoat layer made of the same material as the undercoat layer is formed on the discontinuous metal film. A method for producing an elastic body. The elasticity having a discontinuous metal coating according to claim 2, wherein the primer coat layer is made of a chlorinated polyolefin resin, and the undercoat layer and the top coat layer are made of an acrylic resin or a polyurethane resin. Body manufacturing method.

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