JP6130743B2 - Rubber protective coating composition and tire - Google Patents

Description

  The present invention relates to a rubber protective coating composition and a tire.

  Conventionally, sidewalls of pneumatic tires are rubber compositions whose main rubber components are high-unsaturated rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber having a high content of double bonds in the main chain. It was formed with things. Such double bonds of highly unsaturated rubbers are known to cause cracks on the rubber surface when left standing or running because they may react with ozone and depolymerize. In order to prevent this, an amine-based anti-aging agent and a crack improving agent such as wax have been blended in the rubber composition of the sidewall. However, the amine-based anti-aging agent has a characteristic of turning brown when blooming on the sidewall surface, and the wax is white when blooming on the surface, and in any case, the appearance of the sidewall portion is impaired. There was a problem.

  In order to solve the above problem, for example, Patent Document 1 discloses (a) a polymer called component I, which includes at least one monomer selected from the group of acrylic acid ester, methacrylic acid ester, and vinyl ester. A polymer based on homopolymers or copolymers and having a glass transition temperature lower than 0 ° C .; and (b) based on hydrophilic silica and at least one monomer selected from the group of acrylic, methacrylic and vinyl monomers Coating a rubber surface of a tire with an aqueous composition comprising an aqueous emulsion of component II selected from the group consisting of homopolymers or copolymers, wherein the homopolymer or copolymer has a glass transition temperature higher than 25 ° C. And the method of preventing said bloom is proposed.

Japanese Patent Laid-Open No. 8-245852

  However, the aqueous composition described in Patent Document 1 cannot be said to have a sufficient improvement in appearance, and because of the low flexibility and followability of the coating when the elastic rubber is coated, There was a problem that peeling was likely to occur.

  Therefore, the present invention provides a rubber that can maintain a good appearance for a long period of time when coated on the rubber surface, has flexibility, and has high adhesion between the formed coating and the rubber surface. An object is to provide a composition for protective coating. Another object of the present invention is to provide a tire that maintains good appearance for a long period of time.

Rubber protective coating composition of the present invention, one or more resin components selected from the group consisting of natural resins and synthetic resins, and viewed including the organically treated layered mineral, wherein the synthetic resin, acrylate resin or urethane It is a resin .
By coating the rubber surface with the rubber protective coating composition, it is possible to suppress bloom on the rubber surface such as an anti-aging agent in the rubber component by the action of the resin component and the layered mineral in the formed film. This makes it possible to maintain a good rubber surface appearance for a long time. In this case, since the layered mineral has a bloom suppressing effect, the resin component to be blended can be selected more widely, focusing on the ability to follow rubber. In particular, by using an organically layered mineral, the dispersibility of the layered mineral in the resin component is good, and it is possible to exert a bloom suppressing effect in a relatively small amount, increasing the amount of the resin component, and its performance It is possible to make it easy to demonstrate. Therefore, the coating film formed from the above composition has the advantages of high flexibility and followability and high adhesion to rubber as an elastic body.

  The resin component is preferably hydrophobic. By making the resin component hydrophobic, it is possible to enhance the dispersibility of the organically treated layered mineral in the resin component.

In the rubber protective coating composition of the present invention, the synthetic resin is an acrylate resin or urethane resin. By using an acrylate resin or a urethane resin as the resin component, it is possible to improve the followability to rubber.

  The organically treated layered mineral is treated with an organic treatment agent containing at least one onium cation selected from the group consisting of an ammonium cation, a phosphonium cation, an oxonium cation, and a sulfonium cation. Is preferred. By treating the layered mineral with the organic treatment agent, the dispersibility of the layered mineral in the resin component can be increased.

  The layered mineral is preferably at least one mineral selected from the group consisting of kaolin mineral, mica, montmorillonite, and talc. Since the mineral has a sufficiently high flatness, it easily spreads in a layered manner in the coating, and the use of this mineral can further enhance the bloom suppressing effect.

  The tire of the present invention is characterized in that it is formed by covering at least a part of the sidewall portion with any one of the above rubber protective coating compositions. Preferably, a colored layer is provided on the film formed of the composition. The tire covered with the rubber protective coating composition has an advantage that the aesthetic appearance of the sidewall portion is maintained for a long period of time.

  According to the present invention, when coated on a rubber surface, it is possible to maintain a good appearance for a long period of time, and a composition for rubber protective coating having high adhesion between the formed film and the rubber surface. Can be provided. Further, according to the present invention, it is possible to provide a tire that maintains a good appearance for a long time.

(Composition for rubber protective coating)
Rubber protective coating composition of the present invention, one or more resin components selected from the group consisting of natural resins and synthetic resins, and viewed including the organically treated layered mineral, wherein the synthetic resin, acrylate resin or urethane It is a resin . Hereinafter, each component contained in the composition will be described in detail.

<Organized layered mineral>
The rubber protective coating composition of the present invention (hereinafter also simply referred to as “composition”) contains an organically treated layered mineral (hereinafter also referred to as “organized layered mineral”). The organic layered mineral content in the composition is preferably 1 to 50% by weight, more preferably 10 to 40% by weight, and even more preferably 20 to 30% by weight. By setting the content of the organic layered mineral to 1% by weight or more, a bloom suppressing effect such as an anti-aging agent on the rubber surface can be sufficiently obtained, and by setting the content to 50% by weight or less, the composition It is possible to form a stable coating on the rubber surface.

The layered mineral is preferably composed of a metal ion such as aluminum, sodium, calcium, magnesium and a salt of silicic acid. Specifically, kaolin mineral, mica, montmorillonite, talc, pyrophyllite, vermiculite, saponite, bentonite. Alternatively, these combinations can be suitably used because particles having high flatness are easily obtained. In particular, montmorillonite can be suitably used because it is easy to obtain one having a high aspect ratio. Here, it is preferable to use a layered mineral having a particle size of 0.001 to 20 μm, particularly 0.01 to 5 μm. Further, it is preferable to use particles having an aspect ratio of 1 to 1000, particularly 10 to 700. By using a layered mineral of particles within the above particle diameter and aspect ratio ranges, the dispersibility in the composition is sufficient, and a blooming suppression effect on the rubber surface of the layered mineral can be sufficiently obtained. . The "aspect ratio" here is the ratio of the length of the smallest rectangle when the particle figure is enclosed in a rectangle, and the length is divided by the length of the short side. Shall be pointed to.
Furthermore, the interlayer distance when the layered mineral is added to the composition is preferably 1.0 nm or more, particularly 1.8 nm or more. By setting it as such an interlayer distance, it has the advantage that the dispersibility of a layered compound is easy to improve. The “interlayer distance” here refers to the distance between the bottom surfaces of the layered compounds.

  For the organic treatment of the layered mineral, it is preferable to use an organic treatment agent containing at least one onium cation selected from the group consisting of an ammonium cation, a phosphonium cation, an oxonium cation, and a sulfonium cation. As the organic treatment agent, those containing an ammonium cation (amine) are more preferable, and in particular, 1-aminoalkane, N-alkyltrimethylamine, and N, N′-dialkyldimethylamine are exemplified. The alkyl preferably has 4 or more carbon atoms.

The organic treatment of the layered mineral using the organic treatment agent may be performed by any known method. For example, the layered mineral may be organically used in advance by a method in which the organic amine and the layered mineral are agitated and contacted in water, washed, desalted, and dried. When mixing the other components, an organic treatment agent may be added at the same time to make it organic at the time of producing the composition. By such an organic treatment, the layered mineral can be easily dispersed in the resin component.
The organically treated layered mineral is also widely used as a commercial product. For example, dimethyl, dehydrogenated tallow treated montmorillonite (manufactured by Rockwood Additives, trade name “cloisite 20A”), dimethyl, dioctadecylamine knight , Trade name “Esven NX”) etc. can be obtained and used organically.

  When the organic treatment agent is added directly to the composition, the preferred addition amount is 1 to 2 times the cation exchange capacity of the layered mineral. By making the addition amount of the organic treatment agent 1 time or more, the layered mineral can be made sufficiently organic, and by making it 2 times or less, the layered mineral can be used without affecting the hardening of the film. Can be organic.

<Resin component>
The rubber protective coating composition of the present invention contains one or more resin components selected from the group consisting of natural resins and synthetic resins. The content of the resin component in the composition is preferably 50 to 99% by weight, particularly 60 to 90% by weight, and more preferably 70 to 80% by weight.

The resin component can be appropriately selected from natural resins and synthetic resins, but the use of synthetic resins is particularly preferable. The synthetic resin is an acrylate resin or urethane resin. The resin component is preferably hydrophobic. Since the acrylate resin and the urethane resin have a high affinity with rubber and a low elastic modulus, they exhibit high adhesion when a film is formed on the rubber surface and easily follow the deformation of the rubber. Therefore, it becomes possible to ensure high adhesion of the coating film to the rubber surface. Moreover, by making it hydrophobic, the dispersibility of the organic layered mineral in the resin component can be improved, and the bloom suppressing effect by the organic layered mineral can be sufficiently obtained.

または下記一般式（２）

（式（１）及び（２）中のＡはジエン系オリゴマー鎖を示し、Ｒ_１は水素原子またはメチル基を示す。）
で表される末端に（メタ）アクリロイル基を有する反応性モノマーを、光重合開始剤や熱ラジカル発生剤によるラジカル重合反応により重合することで得られるものが好ましい。
上記式中のＡのジエン系オリゴマーとしては、ポリブタジエン、ポリイソプレン、スチレン―ブタジエンコポリマー、アクリロニトリル―ブタジエンコポリマー、ポリクロロプレン、ポリウレタンが挙げられる。
また、（メタ）アクリロイル基を有する反応性モノマーとしては、側鎖が疎水性官能基を有するものを用いることができる。具体的には，メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ｎ−ブチル（メタ）アクリレート、イソブチル（メタ）アクリレート、ｔｅｒｔ−ブチル（メタ）アクリレート、イソデシル（メタ）アクリレート、ドデシル（メタ）アクリレート、イソミリスチル（メタ）アクリレート、ステアリル（メタ）アクリレート、フェノキシエチル（メタ）アクリレート、ベンジル（メタ）アクリレート、ボルニル（メタ）アクリレート、イソボルニル（メタ）アクリレート、２−メチル−２−アダマンチル（メタ）アクリレート，などを挙げることができる。これらは１種を単独で用いても良く、２種以上を組み合わせて用いても良い。ここで、「（メタ）アクリロイル基」とは、アクリロイル基とメタクリロイル基を両方包含し、「（メタ）アクリレート」とは、アクリレートとメタクリレートの両方を包含する。 Especially as a resin component, hydrophobic polyacrylate can be used conveniently. Here, the hydrophobic polyacrylate is preferably energy curable. Specifically, the hydrophobic polyacrylate has the following general formula (1):

Or the following general formula (2)

(A in the formulas (1) and (2) represents a diene oligomer chain, and R ₁ represents a hydrogen atom or a methyl group.)
Those obtained by polymerizing a reactive monomer having a (meth) acryloyl group at the terminal represented by a radical polymerization reaction with a photopolymerization initiator or a thermal radical generator are preferred.
Examples of the diene oligomer of A in the above formula include polybutadiene, polyisoprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polychloroprene, and polyurethane.
Moreover, as a reactive monomer which has a (meth) acryloyl group, what has a hydrophobic functional group in a side chain can be used. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isodecyl (meth) acrylate , Dodecyl (meth) acrylate, isomyristyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, 2-methyl-2 -Adamantyl (meth) acrylate, etc. can be mentioned. These may be used alone or in combination of two or more. Here, “(meth) acryloyl group” includes both acryloyl group and methacryloyl group, and “(meth) acrylate” includes both acrylate and methacrylate.

  Examples of the photopolymerization initiator include aminoacetophenones, benzoin derivatives, benzyl ketals, hydroxyacetophenones, aminoacetophenones, and the like. As the thermal radical generator, hydroperoxide, dialkyl peroxide, peroxyketal, peroxyester, peroxydicarbonate, diacyl peroxide, and the like can be used.

  When the resin component is a urethane resin, a two-component curable urethane resin (polyol and isocyanate) can be preferably used. Preferable examples of the polyol used include polyester polyol, polyether polyol, and polycarbonate polyol. In addition, preferred examples of the isocyanate used include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and isophorone diisocyanate (IPDI). As a method for preparing the composition, it is preferable to mix one liquid in which a polyol and an organic layered mineral are mixed in advance and two liquids containing isocyanate immediately before use.

<Other ingredients>
In addition to the resin component and the organic layered mineral, the composition of the present invention may contain compounding agents such as an ultraviolet absorber, an antioxidant, a light stabilizer, an adhesion promoter, a rheology modifier, and a dispersant as necessary. You may mix | blend.

  The composition of this invention can be produced | generated by mixing the said formulation with a Banbury mixer, a mechanical stirrer, etc. on the conditions of 10-35 degreeC.

(Coating)
A method for forming a film on the rubber surface of a tire or the like using the composition is not particularly limited. For example, after applying the composition on a vulcanized rubber surface by a method such as screen printing, ink jet printing, letterpress printing, tampo printing, etc., the coating layer is irradiated with light or heated to be cured. A film can be formed on the substrate. Alternatively, the film may be provided on the rubber surface by in-mold molding in which the film obtained by applying the composition on a release film in advance and curing by light irradiation or heating is inserted during rubber vulcanization. .

Although it does not specifically limit about the thickness of the said film, For example, when using as a member of a tire, it is preferable that it is the range of 5-100 micrometers, especially the range of 50-100 micrometers. If the thickness is less than 5 μm, the bloom suppression effect on the rubber surface of the tire may not be sufficiently obtained, and if it exceeds 100 μm, the production cost increases.
On the film formed of the composition of the present invention, a colored layer may be further formed by a method such as applying a colorant. In this case, in order to conceal black on the tire side, it is preferable to form a white layer first and to form 1 to 3 color layers thereon. The thickness of the white layer is preferably about 10 to 40 μm, and the thickness of the color layer is preferably about 5 to 30 μm, although it depends on the amount of white pigment to be blended.

(tire)
The tire according to the present invention is characterized by having a coating containing the above-described composition on at least a part of the surface of the sidewall portion. Formation of the film can be realized by a known method such as application of a composition. Moreover, although it is preferable to form a film on the entire sidewall, it may be formed only in a partial region where a colored layer needs to be provided. Further, a film may be formed on a vulcanized tire, or a composition film in the form of a film may be placed on a non-vulcanized green tire and vulcanized. By having the coating film, it is possible to prevent the appearance of the sidewall portion from being deteriorated by bloom such as an anti-aging agent. Furthermore, when a colored layer is formed on the film, the discoloration is prevented for a long time, and the aesthetic appearance of the coloring can be maintained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

(Examples 1-22 and Comparative Examples 1-6)
(1) Preparation of composition test piece for rubber protective coating According to the formulation shown in Table 1, various components were mixed to prepare various compositions. Various compositions were cured to obtain film-like test pieces having a length of 50 mm × width of 10 mm × thickness of 300 μm. Here, the composition containing the photocurable acrylate resin is SUBZERO 085 (UV lamp system, manufactured by Integration Co., Ltd., output: 100 W / cm), integrated light quantity is 200 mJ / cm ² , peak illuminance is 1200 mW / cm ^2. Cured under the conditions of About the composition containing a urethane resin, after 2 liquid mixing, it left still at 40 degreeC and 20 hours, and was hardened.

(Composition evaluation)
(1) Crack tear strength About each test piece of said composition, tear strength was measured based on JISK6252 (2007) using Shimadzu Corporation autograph AGS-100D. The measurement results were as shown in Table 1.

(2) Elastic deformation maximum elongation rate About each test piece of said composition, it pulled at a speed | rate of 500 / mm, and measured the maximum elongation rate and Young's modulus in an elastic deformation area | region. The measurement results of the maximum elongation were as shown in Table 1. The Young's modulus was all in the range of 0.5 MPa to 20 MPa.

(3) Peel adhesive strength Raw materials shown in Table 2 were mixed by a Banbury mixer to prepare a rubber composition, which was vulcanized at 160 ° C. for 10 minutes, and a rubber member (length 50 mm × width 10 mm × thickness 2 mm) Was made. Next, a film having a thickness of 100 μm obtained by curing each composition was laminated on the surface of the obtained rubber member, and a test piece of a rubber laminate was produced.
Subsequently, each test piece of the rubber laminate was subjected to a 90 ° peel test at a tensile rate of 5 cm / min in accordance with JIS K 6854 (1999), and the peel adhesive strength of the coating (composition film) was measured. The measurement results were as shown in Table 1.

(4) Contamination resistance Raw materials (including anti-aging agents) shown in Table 2 were mixed with a Banbury mixer to prepare a rubber composition, and a rubber member (length 100 mm × width 50 mm × thickness 2 mm) was produced. . On the rubber member thus obtained, various compositions were produced by the method shown in [0031] to obtain a laminate. Next, a test piece of each three-layer rubber laminate was prepared by pressing a vulcanized white rubber sheet (length 100 mm × width 50 mm × thickness 2 mm) at room temperature. The obtained laminate was heated in a constant temperature bath at 100 ° C. for 48 hours, and the color difference of the white rubber surface before and after heating was measured using a spectrocolorimeter CM-700d (manufactured by Konica Minolta Co., Ltd.). Sex was evaluated. The measurement results are shown in Table 1. In addition, the reciprocal number of the relative value which set the color difference of the comparative example 1 to 100 is shown, and the higher the numerical value, the higher the stain resistance and the better.

(Tire evaluation)
The compositions of Example 4 and Comparative Example 1 shown in Table 1 were prepared and applied to the surface of the sidewall portion of a commercially available tire (Ecopia EX10), and SUBZERO 085 (UV lamp system, manufactured by Integration, output 100 W / cm). ) Was cured under the conditions of an integrated light amount of 200 mJ / cm ² and a peak illuminance of 1200 mW / cm ² . As a result, a film having a thickness of 50 μm was formed on the surface of the sidewall portion. Next, a colorant (Rubber Paint White manufactured by Turner Color Co., Ltd.) was applied to a film thickness of 100 μm. The tire was left standing at 60 ° C. for 300 hours, and the change in appearance was visually confirmed.

* 1 Kaolinite average particle size 1μm, aspect ratio 500, interlayer distance 0.7nm
* 2 Montmorillonite average particle size 0.3μm, aspect ratio 500, interlayer distance 1.2nm
* 3 Talc average particle size 1μm, aspect ratio 100, interlayer distance 0.5nm

  From the results of Table 1, it was found that in all of the examples of the present invention, the crack tear strength of the coating and the peel adhesion with rubber were sufficiently high. Furthermore, compared with the comparative example, it turned out that an Example has high pollution resistance and can maintain the external appearance of a rubber surface favorable.

  As described above, the stability of the appearance of the tire in which the composition coating of Example 4 and Comparative Example 1 and the colored layer were formed on the sidewall portion was examined (visual change was visually confirmed). In Example 4, the colored layer was partially browned, whereas in Example 4, the colored layer was hardly discolored.

  According to the present invention, the coating of the rubber protective coating composition of the present invention is formed on the surface of a rubber article, such as the surface of a sidewall of a tire, thereby preventing discoloration of the rubber surface and improving the good appearance. It is possible to hold for a period. Therefore, the invention can be used in the industrial field of tire manufacture and other rubber article manufacture.

Claims (6)

One or more resin components selected from the group consisting of natural resins and synthetic resins, and the organic-treated layered mineral seen including,
The composition for rubber protective coating , wherein the synthetic resin is an acrylate resin or a urethane resin .   The rubber protective coating composition according to claim 1, wherein the resin component is hydrophobic.   The organically treated layered mineral is a layered mineral treated with an organic treatment agent containing at least one onium cation selected from the group consisting of an ammonium cation, a phosphonium cation, an oxonium cation, and a sulfonium cation. The rubber protective coating composition according to claim 1.   2. The rubber protective coating composition according to claim 1, wherein the layered mineral is at least one mineral selected from the group consisting of kaolin mineral, mica, montmorillonite, and talc. A tire comprising a coating film in which at least a part of a sidewall portion is coated with the rubber protective coating composition according to any one of claims 1 to 4 . The tire according to claim 5 , further comprising a colored layer on the coating.