JP2005162924A - Surface treatment agent for silicone gel molded body and silicone gel molded body - Google Patents

Abstract

Provided is a surface treatment agent that can make the surface of a silicone gel molded article low-tacky or non-tacky, and that allows easy adjustment of viscosity and good storage stability.
The surface treating agent of the present invention comprises (A) a polyorganohydrogensiloxane having two hydrogen atoms bonded to a silicon atom in one molecule and (B) an alkenyl bonded to a silicon atom in one molecule. A polyorganosiloxane having two groups and (C) an inorganic filler, and the content ratio of the component (C) is 10 to 60% by weight based on the component (B). The component (A) and the component (B) 5 to 20% by weight based on the total of the components. This surface treatment agent is a cured product of an addition reaction curable silicone composition and is suitable for surface treatment of a silicone gel molded article having a penetration of 1 to 120 (based on ASTM D1408).
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Description

  The present invention relates to a surface treatment agent for a silicone gel molded body, and in particular, a surface treatment used to reduce surface tackiness in a silicone gel molded body used for surface protection and heat dissipation of electronic parts and the like. It relates to the agent. Moreover, this invention relates to the silicone gel molded object by which the surface was processed with the surface treating agent.

  Silicone gel-like cured products are called silicone gels, and are excellent in heat resistance, cold resistance, vibration proofing, shock absorption, etc., to protect electrical and electronic parts from thermal and mechanical failure. It is used for various applications such as coating materials and shock absorbing materials.

  However, since the surface of the silicone gel is highly tacky, dust and dust are likely to adhere to it, and there is a problem in work such as that the molded body cannot be placed on the silicone gel. Further, since the mechanical strength is insufficient, there is a problem that the silicone gel molded body is lost when removing attached dust and the like.

  As a method for eliminating these drawbacks, as described below, it has been proposed to provide a non-adhesive protective layer on the surface of the silicone gel molded body.

  That is, a method has been proposed in which polyorganohydrogensiloxane or the like is applied to the surface of a silicone gel sheet, diffused in the gel, and then heat-cured to provide an elastomeric or resinous silicone layer on the surface. (For example, see Patent Document 1)

  In addition, polyorganohydrogensiloxane is applied to the surface of the uncured silicone gel composition and heated before diffusion, so that the inner silicone gel composition and the surface layer into which the polyorganohydrogensiloxane is incorporated are simultaneously formed. A method of providing a silicone elastomer layer on the surface by curing is proposed. (For example, see Patent Document 2 and Patent Document 3)

  However, in the method described in Patent Document 1, since the treatment liquid needs to be applied to the cured gel surface, the process is complicated. Select the type and amount of polyorganohydrogensiloxane having functional groups that react with the remaining functional groups in the silicone gel so that the polyorganohydrogensiloxane does not remain uncured on the silicone gel surface. Had to do. Otherwise, there has been a problem that it is necessary to remove it by washing or wiping after curing or applying high heat.

  In addition, in the method described in Patent Document 2 or Patent Document 3, since the polyorganohydrogensiloxane having a large number of active Si—H is included as a crosslinking component, the surface treatment layer adheres to the peelable substrate. In order to prevent this, a low molecular weight silicone oil for release had to be added.

Furthermore, since the viscosity of the surface treatment agent is low, the surface layer hardens unevenly as a result of being diffused into the silicone gel, and a good protective layer is not obtained. There was a problem that control was difficult.
Japanese Patent Publication No. 1-25704 Japanese Patent Publication No. 6-88281 JP 9-207275 A (Patent Registration No. 3280224)

  The present invention has been made to solve these problems, and can reduce the tackiness of the surface of the silicone gel molded body, or can impart non-tackiness, and can be easily adjusted in viscosity and storage stability. An object of the present invention is to provide a surface treatment agent that is good and industrially easy to use.

  The surface treating agent for a silicone gel molded article of the present invention is (A) a polyorganohydrogensiloxane having two hydrogen atoms bonded to silicon atoms in one molecule, and (B) a silicon atom bonded to one molecule. A polyorganosiloxane having two alkenyl groups, and (C) an inorganic filler, wherein the content ratio of the (C) inorganic filler is 10 to 60% by weight with respect to the component (B), and It is 5 to 20% by weight based on the total amount of the component (A) and the component (B).

  In addition, the silicone gel molded body of the present invention has the surface treatment described above on the surface of a silicone gel molded body having a penetration of 1 to 120 as defined in ASTM D1408 obtained by curing an addition reaction curable silicone composition. A surface treatment layer made of an agent is formed.

  According to the surface treating agent of the present invention, the surface of the silicone gel molded body can be made to be low-tacky or non-tacky. The surface treatment agent of the present invention is easy to adjust the viscosity and excellent in storage stability, and is suitable for industrial mass production.

  Furthermore, the silicone gel molded body treated with the surface treating agent of the present invention and having at least a part of the surface made low-tacky or non-tacky is excellent in handling workability. For example, it can be used for potting or conformal coating of electronic parts.

  Hereinafter, embodiments of the surface treatment agent of the present invention and a silicone gel molded body surface-treated with the surface treatment agent will be described.

  Embodiments of the surface treating agent of the present invention include (A) a polyorganohydrogensiloxane having two hydrogen atoms bonded to a silicon atom in one molecule, and (B) an alkenyl group bonded to a silicon atom in one molecule. Each of the polyorganosiloxane having 2 and (C) an inorganic filler, and the content of the inorganic filler as the component (C) is 10 to 60% by weight with respect to the component (B). It is a ratio of 5 to 20% by weight with respect to the total amount of the component and the component (B).

  This surface treatment agent is suitably used as a treatment agent for reducing the adhesiveness of the surface of the silicone gel molded body. Here, a silicone gel molded body (for example, a silicone gel sheet) is a composition in which silicone (polyorganosiloxane) as a main component is partially formed into a three-dimensional network structure by crosslinking, and is deformed or limited by the application of stress. The hardened | cured material used as the state which shows the fluidity | liquidity is said, and especially the hardened | cured material of an addition reaction curable silicone composition is applied.

  The penetration of this silicone gel molded body is 1 to 120, preferably 5 to 110, more preferably 5 to 80, as measured by a method based on ASTM D1408. Silicone gels with a penetration of less than 1 are poor in surface tackiness and shape followability, which limits the application of the molded product and makes almost no demand for reducing tackiness. Soft silicone gels or fluid silicone gels with a penetration of over 120 are difficult to use because the resulting molded article is extremely difficult to handle. Further, due to the action of the surface treatment agent, the gel surface is wrinkled or cracked due to the difference in strength between the surface and the internal gel, which is not preferable.

  Specifically, a gel-like molded body obtained by curing a silicone composition containing an inorganic filler is used. Examples of commercially available silicone compositions include one-component TSE3051, TSE3051L, TSE3053, TSE3055, two-component YE5818, TSE3062, TSE3070, and XE14-B7393 (all trade names of GE Toshiba Silicone Co., Ltd.). The The size of the molded body is not particularly limited, but the shape is a sheet shape or a block shape.

  These silicone gel molded bodies are used for insulation, protection and buffering of electronic parts. Among these, silicone gel sheets for potting are used for applications such as sealing of hybrid ICs, sealing of various sensors, sealing of power modules, dampers and the like.

  In the surface treatment agent of the embodiment, as the polyorganohydrogensiloxane of the component (A), in particular, those having hydrogen atoms bonded to silicon atoms at both ends of the molecule are used.

  Examples of organic groups other than hydrogen atoms bonded to silicon atoms include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, octyl groups, decyl groups, dodecyl groups and other alkyl groups, 2-phenylethyl Group (benzyl group), aralkyl group such as 2-phenylpropyl group, aryl group such as phenyl group and halogenated alkyl group such as chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, etc. Is exemplified. From the viewpoint of easy synthesis, a methyl group or a phenyl group is preferable.

  Examples of the molecular structure of the component (A) include a straight chain, a partially branched straight chain, a ring, a branched chain, and the like, but a substantially straight chain is preferable.

  The viscosity of component (A) at 25 ° C. is 0.5 to 500 mPa · s because the handling property of the surface treatment agent is good and the physical properties of the silicone gel obtained as a result of the surface treatment are good. It is preferable that it is the range of 5-120 mPa * s especially. When the viscosity of the component (A) is less than 0.5 mPa · s, the surface treatment agent diffuses too quickly on the silicone gel molded article and easily penetrates into the interior, resulting in a non-uniform surface treatment layer. When it exceeds 500 mPa · s, the effect of reducing the tackiness by the treatment is almost lost.

  Component (B) is a polyorganopolysiloxane having two alkenyl groups bonded to silicon atoms in one molecule, and holds the inorganic filler (C) described later and functions to adjust the viscosity of the entire treatment agent. Have. Examples of the molecular structure of component (B) include linear, partially branched linear, cyclic, and branched.

  Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and a heptenyl group, and a vinyl group is particularly preferable. Examples of the bonding position of the alkenyl group in component (B) include molecular chain terminals and / or molecular chain side chains. Examples of the organic group bonded to the silicon atom other than the alkenyl group of the component (B) include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group; phenyl group, tolyl Aryl groups such as a group, xylyl group and naphthyl group; aralkyl groups such as benzyl group and phenethyl group; and halogenated alkyl groups such as chloromethyl group, 3-chloropropyl group and 3,3,3-trifluoropropyl group In particular, a methyl group and a phenyl group are preferable.

  The viscosity (25 ° C.) of the component (B) is excellent in handling workability of the surface treatment agent and good physical properties of the silicone gel obtained as a result of the surface treatment. It is preferably in the range of 000 mPa · s, particularly preferably in the range of 5,000 to 20,000 mPa · s. When the viscosity of the component (B) is less than 5,000 mPa · s, the blending amount of the component (B) must be increased in order to bring the viscosity of the treatment agent to a desired value, and as a result, curing is delayed. . On the other hand, if the viscosity exceeds 50,000 mPa · s, the blending amount of the inorganic filler must be reduced, and as a result, the effect of reducing the adhesiveness becomes insufficient.

  The inorganic filler (C) used in the embodiment of the present invention is fumed silica, precipitated silica, hydrophobized fumed silica, hydrophobic precipitated silica, quartz fine powder, alumina, calcium carbonate, zinc oxide, titanium dioxide. Selected from the group consisting of Two or more types of mixtures may be used. From the viewpoint of storage stability, it is particularly desirable to use fumed silica. In order to improve dispersibility, the surface of the inorganic filler described above may be treated with a silane coupling agent, silazane, higher fatty acid or higher fatty acid salt, etc. In the case of an inorganic filler other than fumed silica, the surface Greatly improves dispersibility by processing.

  (C) Content of an inorganic filler shall be the ratio of 10-60 weight% with respect to (B) component, and the ratio of 5-20 weight% with respect to the total amount of (A) component and (B) component, To do. And the viscosity of the whole surface treating agent is adjusted to the range of 50-5000 mPa * s (25 degreeC), More preferably, 300-1200 mPa * s.

  (C) When the content of the inorganic filler exceeds 60% by weight with respect to the component (B) or exceeds 20% by weight with respect to the total amount of the components (A) and (B), the surface treatment is performed. The fluidity of the agent becomes poor, and the processing workability is deteriorated.

  A platinum-based catalyst can be blended in the surface treatment agent of the embodiment. Examples of the platinum-based catalyst include chloroplatinic acid, an alcohol solution of chloroplatinic acid, a platinum-olefin complex, a platinum-alkenylsiloxane complex, and the like. By using a platinum-based catalyst in combination, the treatment layer with the surface treatment agent can be made tougher.

  A platinum-type catalyst can be contained so that a platinum-type metal may become a ratio of about 1-50 ppm (weight unit) of the whole surface treating agent. Furthermore, in order to improve the adhesion to the silicone gel molded body, a platinum catalyst and a compound having a silane coupling agent and / or an organic polyfunctional unsaturated substituent can be used in combination.

  Furthermore, a binder, a dispersant, a lubricant, an antistatic agent, and the like may be added to the surface treatment agent of the embodiment of the present invention as necessary.

  As binder, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer, methacrylic ester-vinylidene chloride copolymer , Methacrylate-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, styrene-butadiene copolymer, polyester resin, chlorovinyl ether -Thermoplastic resins such as acrylic acid copolymers and amino resins; and phenol resins, phenoxy resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd trees , Silicone resin, acrylic reaction resin, vinyl chloride-vinyl acetate resin, mixture of methacrylate copolymer and diisocyanate prepolymer, mixture of high molecular weight polyester resin and isocyanate prepolymer, urea formaldehyde resin, polyester polyol and isocyanate And a thermosetting resin such as a polycarbonate type polyurethane, a polyamide resin, a low molecular weight glycol / high molecular weight diol / triphenylmethane triisocyanate mixture, and a mixture thereof.

  Examples of the dispersant include lecithin; fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid; and sulfate esters.

  Examples of the lubricant include silicone oil, graphite, molybdenum disulfide, and tungsten disulfide.

  Examples of the antistatic agent include conductive powders such as carbon black, graphite, tin oxide-antimony oxide compound, titanium oxide-tin oxide-antimony oxide compound; natural surfactants such as saponin; alkylene oxides, glycerin , Nonionic surfactants such as glycidols; cationic surfactants such as higher alkylamines, quaternary ammonium salts, pyridine and other heterocyclic rings, phosphonium or sulfoniums; carboxylic acids, sulfonic acids, phosphoric acids, Examples include anionic surfactants containing acidic groups such as sulfate ester groups and phosphate ester groups; surfactants such as amino acids, aminosulfonic acids, sulfuric acid or phosphate esters of amino alcohols, and the like.

  In order to obtain the surface treatment agent of the embodiment, first, the inorganic filler that is the component (C) and various additives that are added as necessary, together with the component (B), a ball mill, a triple roll, an attritor, a sand mill, etc. Stir and mix using a disperser. And the surface treating agent is prepared by dissolving the obtained compound in polyorganohydrogensiloxane which is the component (A).

  In order to treat the surface of the silicone gel molded body using this surface treatment agent, for example, after the surface treatment agent is applied in a thin film on a peelable substrate, a polyorganosiloxane, an inorganic filler, etc. A silicone composition mixed at a predetermined ratio using a mogul, kneader, planetary mixer or the like is injected so as to have a predetermined thickness, and a peelable substrate is further disposed thereon, and the above-described silicone composition Is sandwiched between two peelable substrates. Next, after forming into a sheet with a calender roll or the like, the silicone gel sheet and the coating layer of the surface treatment agent are simultaneously cured.

  The surface treatment agent layer gradually cures even when left at room temperature, and forms a cured film on the surface of the silicone gel sheet, but treats only the surface in a shorter time and with as little penetration and diffusion as possible. Therefore, heat treatment is performed at a temperature of 40 to 150 ° C., preferably 40 to 120 ° C., more preferably 50 to 120 ° C. for 1 minute to 120 minutes, preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes. The method to do is more effective.

  As the peelable substrate, for example, a film or paper of a polyester resin such as a fluororesin, a polypropylene resin, a polyethylene resin, or polyethylene terephthalate, or a substrate obtained by further coating a release agent on these substrates can be used.

The amount of the surface treatment agent applied to the peelable substrate is 0.05 to 2.0 g / m ^2, preferably 0.1 to 0.7 g / m ² . In order to apply the surface treatment agent on the peelable substrate, for example, it may be applied directly by a Mayer bar, a gravure roll, a reverse roll, a knife coater or the like. Moreover, after diluting a surface treating agent with the organic solvent and apply | coating on a peelable base material by the method similar to the above, you may heat and volatilize the organic solvent. Further, a binder resin such as polyethylene and a surface treatment agent may be mixed in an organic solvent and applied in the same manner.

  The adhesive strength of the surface treatment agent layer is not particularly limited as long as it is smaller than the adhesive strength of the surface of the silicone gel sheet. This difference in adhesive strength can be confirmed by finger touching, but can preferably be confirmed by measurement with a probe tack tester in accordance with the method prescribed in ASTM D2979. It is practically preferable that the value measured with a probe tack tester is 60% or less of the adhesive strength of the silicone gel sheet surface.

  According to the surface treating agent of the embodiment of the present invention, the surface of the silicone gel molded body can be made to be low-tacky or non-tacky. And since the surface-treated silicone gel molding is excellent in handling workability, it can be used as a pressure-sensitive adhesive sheet having shape followability for potting or conformal coating of semiconductors and electronic parts. In addition, heat-conducting fillers such as power transistors, power modules, thyristors, rectifiers, transformers, etc. can be brought into close contact with radiating fins and metal heat sinks by blending a silicone gel molded body with a heat conductive filler. It can be used as a thermally conductive silicone gel sheet for efficiently radiating heat generated from the electric / electronic parts.

  Further, the surface treatment agent of the embodiment is easy to adjust the viscosity and excellent in storage stability, and is suitable for industrial mass production.

  Next, the present invention will be described with reference to specific examples, but the present invention is not limited thereto. In addition, a part shows a weight part,% shows weight%, respectively, and a viscosity shows the value in 25 degreeC.

Example 1
30 parts of a silicone compound (silica content 50%) in which dimethylpolysiloxane having a viscosity of 10,000 mPa · s and having both ends of a molecular chain blocked with a dimethylvinylsiloxy group and fumed silica are mixed is represented by the chemical formula:
Mixing and dispersing in 70 parts of polydimethylhydrogensiloxane represented by (CH ₃ ) ₂ HSiO (Si (CH ₃ ) ₂ O) ₂₀ Si (CH ₃ ) ₂ H gave a treatment liquid having a viscosity of 500 mPa · s. . Even when this treatment solution was allowed to stand at 50 ° C. for 1 month, no separation, layer separation, or change in viscosity was observed.

  Next, 100 parts of alumina was added to 100 parts of a liquid silicone rubber composition XE14-B7373 (trade name of GE Toshiba Silicone) and mixed uniformly, and the treatment liquid obtained above was applied. After pouring onto a PET film and covering with an uncoated PET film from above to form a sheet having a desired thickness (1 mm), it was cured by heating at 150 ° C. for 5 minutes.

  The penetration of the silicone gel sheet thus obtained was measured by the method prescribed in ASTM D1408 and found to be 20. Moreover, as a result of measuring the adhesive strength of the surface of this silicone gel sheet with a probe tack tester (manufactured by TESTING MACHINES INC), the treatment solution was applied to the adhesive force on the uncoated side being 130 gf / 5 mm diameter. The adhesive strength on the side was 35 gf / 5 mm, and it was found that the adhesive strength was greatly reduced by application of the treatment liquid.

Example 2
10 parts of dimethylpolysiloxane having both ends of a molecular chain having a viscosity of 10,000 mPa · s blocked with a dimethylvinylsiloxy group and a chemical formula:
10 parts of alumina was added to the composition obtained by mixing 60 parts of polydimethylhydrogensiloxane represented by (CH ₃ ) ₂ HSiO (Si (CH ₃ ) ₂ O) ₂₀ Si (CH ₃ ) ₂ H. Then, a treatment liquid having a viscosity of 400 mPa · s was obtained.

  Next, on the PET film coated with this treatment solution, 100 parts of XE14-B7393 added with 300 parts of alumina and mixed uniformly is poured, and the uncoated PET film is further covered from above with a desired thickness. After being molded into a thickness (1 mm), it was cured by heating at 150 ° C. for 5 minutes.

  The penetration of the silicone gel sheet thus obtained was measured according to ASTM D1408 and found to be 20. Further, the adhesive strength of the surface of this silicone gel sheet was measured with a probe tack tester in the same manner as in Example 1. As a result, the adhesive strength on the uncoated side was 125 gf / 5 mm, and the treatment liquid was applied. The adhesive strength on the side was 33 gf / 5 mm, and it was found that the adhesive strength was greatly reduced by the application of the treatment liquid.

Comparative Example 1
10 parts of dimethylpolysiloxane having both ends of a molecular chain having a viscosity of 10,000 mPa · s blocked with dimethylvinylsiloxy groups, and a chemical formula:
A treatment liquid was prepared by mixing 60 parts of polydimethylhydrogensiloxane represented by (CH ₃ ) ₂ HSiO (Si (CH ₃ ) ₂ O) ₂₀ Si (CH ₃ ) ₂ H.

  Next, on the PET film coated with this treatment solution, a mixture of 100 parts of XE14-B7393 with 300 parts of alumina and mixed uniformly is poured onto the PET film coated with this treatment solution. The uncoated PET film was applied to form a desired thickness (1 mm), and then cured by heating at 150 ° C. for 5 minutes.

  The penetration of the silicone gel sheet thus obtained was measured according to ASTM D1408 and found to be 20.

  Moreover, when the adhesive strength of the surface of this silicone gel sheet was measured with a probe tack tester in the same manner as in Example 1, the treatment solution was applied to the adhesive force on the uncoated side being 120 gf / 5 mm in diameter. The adhesive strength on the side was 75 gf / 5 mm diameter, and a sufficient reduction in the adhesive strength was not observed by application of the treatment liquid.

Comparative Example 2
Chemical formula: (CH ₃ ) ₂ HSiO (Si (CH ₃ ) ₂ O) ₂₀ Si (CH ₃ ) ₂ H 90 parts of polydimethylhydrogensiloxane is added and mixed with 10 parts of alumina to prepare a treatment solution. did.

  Next, on the PET film coated with this treatment solution, 100 parts of XE14-B7393 added with 300 parts of alumina and mixed uniformly is poured, and the uncoated PET film is further covered from above with a desired thickness. After being molded into a thickness (1 mm), it was cured by heating at 150 ° C. for 5 minutes.

  The penetration of the silicone gel sheet thus obtained was measured according to ASTM D1408 and found to be 20.

  Moreover, when the adhesive strength of the surface of this silicone gel sheet was measured with a probe tack tester in the same manner as in Example 1, the adhesive strength on the uncoated side was 120 gf / 5 mm, whereas the surface treatment agent was applied. The pressure-sensitive adhesive force on the side was 40 gf / 5 mm, and the pressure-sensitive adhesive strength was greatly reduced. However, within 1 hour, alumina settled and separated from the treatment solution, and it became impossible to use.

  The surface treatment agent of the present invention is easy to adjust the viscosity and excellent in storage stability, and can make the surface of the silicone gel molded article low or non-adhesive. Thus, the silicone gel molded body treated with the surface treatment agent of the present invention and having at least a part of the surface made low-tacky or non-tacky is excellent in handling workability, and thus has a shape-following pressure-sensitive adhesive sheet, etc. It can be used for potting or conformal coating of electronic parts.

Claims (5)

(A) a polyorganohydrogensiloxane having two hydrogen atoms bonded to silicon atoms in one molecule; (B) a polyorganosiloxane having two alkenyl groups bonded to silicon atoms in one molecule; ) Each containing inorganic filler,
The content ratio of the inorganic filler (C) is 10 to 60% by weight with respect to the component (B), and 5 to 20% by weight with respect to the total amount of the components (A) and (B). A surface treatment agent for a silicone gel molded article, characterized in that it exists.   2. The viscosity at 25 ° C. of the polyorganohydrogensiloxane having two hydrogen atoms bonded to silicon atoms in one molecule (A) is 0.5 to 500 mPa · s. Surface treatment agent for silicone gel moldings.   The viscosity at 25 ° C of the polyorganosiloxane having two (B) two alkenyl groups bonded to silicon atoms in one molecule is 5,000 to 50,000 mPa · s. The surface treatment agent for a silicone gel molded article as described.   The surface treatment agent for a silicone gel molded article according to any one of claims 1 to 3, wherein the viscosity at 25 ° C is 50 to 5000 mPa · s.   The surface treating agent according to any one of claims 1 to 4, wherein the surface treatment agent is formed on a surface of a silicone gel molded article having a penetration of 1 to 120 as defined in ASTM D1408 obtained by curing an addition reaction curable silicone composition. A silicone gel molded article, wherein a surface treatment layer is formed.