JP3532052B2 - Room temperature drying type undercoat material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room-temperature drying type undercoat material, and more particularly, to a substrate having stable surface properties and high water repellency. The present invention relates to a room temperature drying type undercoat material which can be coated well and has good chipping resistance. 2. Description of the Related Art A vehicle body is coated with a coating mainly for the purpose of preventing rust and imparting an aesthetic appearance. Generally, one paint
One material cannot satisfy all performances,
Conventionally, as a coating structure of an automobile body, conventionally, generally, a base coat, a middle coat, and a top coat are sequentially laminated on a pretreated steel sheet base surface. Further, as the composition of the top coat, as in a so-called solid coating using an amino-alkyd resin paint, or as a so-called metallic coating using a thermosetting acrylic resin paint, as in a pearl tone coating There is a two-layer structure consisting of a base coat and a clear coat provided on the base coat. In recent years, a clear coat made of a fluororesin having excellent weather resistance, chemical resistance and water repellency and having a high gloss retention has been used as a clear coat in the metallic coating or the like, or as a protective coat in a solid coating. It is also used to have a two-layer structure of a color base and a clear coat. [0004] In recent years, as the performance of tires has become higher, the number of customers who are concerned about the slap noise of tires has been increasing. As a countermeasure, an undercoat may be applied to the underside of a side sill of an automobile body. [0005] When the underbody is to be applied to the underside of the side sill or the like after the entire vehicle body is painted by the above-described method and the undercoating material is to be applied to the underside of the side sill, the overcoating of the overcoating is applied to portions other than these portions. It is necessary to maintain image clarity, and the usable paints are necessarily limited to those of a room temperature drying type. Conventionally, as such an undercoat material, a styrene-butadiene rubber (SBR) latex, which is a water-based coating at room temperature, has been used. [0007] However, such a conventional SBR is formed on a substrate (coating film) having stable surface properties and high water repellency, such as a clear coat made of a fluororesin as described above. When an undercoat material made of latex is applied, problems such as poor adhesion and the desired chipping resistance cannot be obtained. Accordingly, an object of the present invention is to provide a novel room-temperature-drying type undercoat material. Another object of the present invention is to provide a room temperature drying-type undercoat material that can be coated with good adhesion onto a substrate surface having stable surface properties and high water repellency and exhibits excellent chipping resistance. Things. The above objects are attained by providing styrene.
-Butadiene rubber and (meth) acrylate
A binder component 100 parts by weight of the system polymers, data
This is achieved by a room-temperature drying type undercoat material applied on a fluororesin-based topcoat paint film, characterized by containing only 150 to 250 parts by weight of luk in water. Hereinafter, the operation of the present invention will be described in more detail with reference to specific embodiments. The room temperature drying type undercoat material of the present invention comprises:
It is characterized by containing a binder component composed of a synthetic rubber latex and / or a synthetic resin emulsion and an extender pigment in a predetermined ratio. As the binder component used in the undercoat material according to the present invention, various synthetic rubber latexes and / or synthetic resin emulsions can be used. In order to obtain various properties such as adhesion, excellent strength, and desired elasticity, a mixture of a styrene-butadiene rubber and a (meth) acrylate polymer is preferable. In addition, styrene, butadiene and (meth)
A copolymer containing an acrylate as a monomer component can also be preferably used. Examples of the (meth) acrylate monomer as a main component of the (meth) acrylate polymer include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylic acid. Examples include 2-ethylhexyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, and the like. Other monomers that can be copolymerized with these (meth) acrylate monomers include, for example, other vinyl monomers such as styrene and its derivatives, or acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylic Glycidyl acrylate, glycidyl methacrylate,
Monomers having a functional group, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl propyl methacrylate, may be mentioned. As the (meth) acrylic ester polymer, the compounding ratio with the styrene-butadiene rubber used in combination,
Depending on the compounding amount of the styrene component in the butadiene rubber, the compounding amount of the extender described below, etc., depending on the film strength and the film elasticity required for the undercoat material film, the room-temperature curing rate It is desirable to appropriately select the monomer component to be copolymerized in consideration of the above. Although not particularly limited, methyl acrylate, ethyl acrylate, acrylate of an alkyl group having a relatively low molecular weight such as n-butyl acrylate as a main component, methyl methacrylate for improving hardness, styrene, An acrylamide component, and a type obtained by copolymerizing acrylic acid and methacrylic acid for further stabilizing the reactivity (crosslinkability) and the emulsion, are preferably used. As an example of such a preferable copolymer, for example, a styrene-n-butyl acrylate copolymer represented by the following general formula (1), a styrene-n-butyl acrylate copolymer represented by the following general formula (2)
And n-butyl acrylate-acrylic acid copolymer and the like. ## STR1 ## Embedded image The amount of the styrene component in the styrene-butadiene rubber is not particularly limited, and various types are used according to the type and amount of the (meth) acrylate polymer used in combination. Preferably, the styrene component is about 30 to 70% by weight. Further, also in the styrene-butadiene rubber, other monomer components such as a monomer having a functional group for cross-linking can be copolymerized if necessary. The extender to be blended in the room-temperature drying type undercoat material of the present invention is not limited at all, and conventionally known extenders can be used alone or in combination of plural kinds. Examples of the extender pigment, for example, magnesium silicate salts typified by talc, clay, aluminum silicate salts typified by kaolin, silica (silicon oxide), titanium oxide, calcium carbonate, Ru include barium sulfate and the like. [0021] In the room temperature drying type undercoat material of the present invention, 150 to 250 parts by weight of the extender is blended with respect to 100 parts by weight of the binder component. The reason for such a mixing ratio is as follows. FIG. 1 shows a grid pattern in which an undercoat material composition obtained by changing the mixing ratio of a binder component and an extender pigment in various ways is formed on a fluororesin-based overcoating film (clear coating film). 3 shows the results of a peeling test and the tensile strength of a coating film of an undercoat material. The amount of the extender pigment is extremely small, for example, when the extender pigment is less than 70 parts by weight with respect to 100 parts by weight of the binder component (A in FIG. 1).
Range), the strength (tensile strength) of the formed undercoat material coating film itself is weak. For example, when the undercoat material coating film is formed on the undercoat material coating film, the undercoat material coating film has a Although no delamination occurs at the boundary surface with the undercoat material coating, peeling occurs in the undercoat material coating, resulting in poor chipping resistance, which is the required performance. Although good results were obtained only by looking at the results of the cross-cut peel test, in actuality, the adhesion strength (apparent adhesion) of the undercoat material to the overcoat film was not high, but the undercoat This is because the strength (tensile strength) of the coating of the material itself is inferior (tensile strength <apparent adhesion) on the balance between the adhesion strength between the topcoat film and the undercoat material film. It's just the result. When the blending amount of the extender is more than 70 to less than 150 parts by weight (range B in FIG. 1), the strength (tensile strength) of the coating film of the undercoat material itself is high, so that the chipping resistance becomes good.
In addition, although the adhesion strength (apparent adhesion) of the undercoat material to the overcoat film is further improved as compared with the case of the above-mentioned A range, the adhesion strength between the high overcoat film and the undercoat material film is improved. In this case, the strength of the coating film itself of the undercoat material becomes too high (tensile strength> apparent adhesion force), and the peeling of the undercoat material film from the topcoat film easily occurs from the topcoat film, It is not satisfactory in terms of adhesion. On the other hand, when the blending amount of the extender pigment is extremely large, exceeding 250 parts by weight with respect to 100 parts by weight of the binder component (range D in FIG. 1), the strength (tensile strength) of the formed undercoat material coating film itself is increased. ) Is weak, and the strength (tensile strength) of the formed undercoat material film itself is also weak, peeling occurs in the undercoat material film, and the undercoat material film can be easily separated from the overcoat film. This is inferior in terms of chipping resistance and adhesion. On the other hand, when the blending amount of the extender in the blending range according to the present invention is 150 to 250 parts by weight with respect to 100 parts by weight of the binder component (range C in FIG. 1), the undercoating material is not coated. Although the strength (tensile strength) of the film itself is slightly inferior to the above-mentioned B range, it shows a considerably high value, so that the chipping resistance is good, and the adhesion strength of the undercoat material to the overcoat film (apparent adhesion). Is further improved as compared with the case of the above-mentioned B range, and the strength of the coating film of the undercoat material itself is more appropriate than the adhesion strength on the balance between the high overcoating film and the adhesion strength of the undercoating material coating film. (Tensile strength <apparent adhesion force), these are moderately balanced, and have good adhesion to the overcoat film of the undercoat material film and excellent chipping resistance. The undercoat coating film to exhibit the Nozomi characteristics. Water is used as a developing medium of the undercoat material of the present invention. The amount of vehicle solids (binder component and extender) in the undercoat agent is 100 parts by weight of water. 150-2
It is about 50 parts by weight. That is, if the compounding amount of the vehicle solid content is less than this, there is a large possibility that a continuous coating film cannot be formed on the overcoating film, and it takes a long time to dry the coating film. This is because if the amount of the vehicle solid content is large, the coating operation becomes difficult, and it is difficult to obtain a coating film having a uniform thickness. Further, in the undercoat material of the present invention,
If necessary, other known additives such as an emulsifier, an emulsion stabilizer, a cross-linking agent, a thickener, a surfactant and the like can be blended. The undercoat material of the present invention is
For example, if it is applied to the substrate surface by a coating method such as spraying, roller coating or brush coating, then, at room temperature, the developing medium evaporates and addition polymerization of the vehicle solids, cross-linking reaction, etc. occur, forming a film to form a cured film. can do. In particular, since the surface properties such as fluororesin topcoats are stable and can be applied with good adhesion to substrates or coatings with high water repellency, a topcoat is formed in automotive body coating. Thereafter, in order to impart chipping resistance to a portion such as the lower surface of the side sill, it is suitably used when an undercoat layer is formed on this overcoat film. Further, since it is a room temperature drying type, it is possible to apply such an undercoat layer later or repaint it according to a customer's request to a car in use. As described above, in applying the undercoat material according to the present invention, there is no particular limitation to the formation of the overcoat film, and various conventionally known methods can be used. From the most common ones, the undercoating (electrodeposition coating), the intermediate coating, and the overcoating coating are sequentially laminated on the surface of the steel plate base by the steps of coating (coating) and baking (baking). The above-mentioned intermediate coating is omitted, the above-mentioned intermediate coating is performed in two coats, and the above-mentioned top coat is a two-layer base coat and a clear coat provided on the base coat. What to do,
Further, various modes such as a three-layer top coat may be employed. Further, the paint constituting the top coat (outermost surface coat) for applying the undercoat material according to the present invention is not particularly limited, and the conventionally used thermosetting acrylic resin clear paint is used. , Fluororesin clear paint,
It can be applied to any of acrylic-silicone resin clear paint, amino-alkyd resin paint, thermosetting oil-free alkyd resin paint, etc., and exhibits good adhesion to any of these types. However, in particular, when the top coat is made of a fluororesin paint, better adhesion can be expected, which is desirable. The coating of the undercoat material according to the present invention comprises:
After the completion of the baking and curing operation of these top coats, they are applied at room temperature and dried and cured. EXAMPLES The present invention will be described more specifically below with reference to examples. Examples and Comparative Examples Test pieces (70 × 150 × 0.8 m) of cold-rolled steel sheets
m) was treated with a zinc phosphate treatment solution (Granodine DP4000,
Chemical treatment with Nippon Paint Co., Ltd., and electrodeposition paint (Powertop U-600, Nippon Paint Co., Ltd.) with a film thickness of 2
After coating so as to have a thickness of 0 μm, it was baked at 170 ° C. for 30 minutes. On top of this, an intermediate coating (High Epico No. 1)
Nippon Oil & Fats Co., Ltd.)
Bake at 140 ° C. for 30 minutes. Further, an acrylic resin-based base coat (Super Luck M-80, manufactured by Nippon Paint Co., Ltd.) was applied thereon so as to have a thickness of 20 μm, and setting was performed for 3 minutes, followed by a fluorine atom-containing vinyl polymer. Fluororesin clear (Super Freon 0-10 Clear, manufactured by Nippon Paint Co., Ltd.) was applied to a thickness of 30 μm and baked at 140 ° C. for 30 minutes. Then, a styrene-butadiene rubber latex (styrene component 50%) and an acrylate-based polymer emulsion were added on top of this in a weight ratio of 60: 4.
It contains a binder component blended at a ratio of 0 and talc as an extender in various ratios, and has a vehicle solid content of about 66% by weight and is dispersed and blended in water as a developing medium. Room temperature dry type undercoat material with film thickness 5
It was applied to a thickness of 00 μm, and the coating was dried and cured at room temperature (25 ° C.). FIG. 2 schematically shows the structure of the coating film formed in this embodiment. As shown, an electrodeposition coating film 2 and an intermediate coating film are sequentially formed on a steel sheet 1. 3,
This means that the top coat base coat 4a, the top coat clear coat (fluororesin-based) 4b, and the room temperature drying type undercoat coat 5 are formed by lamination. Using the coated product thus obtained as a test plate, the adhesion of the undercoat material coating film and the tensile strength were evaluated. The results obtained are shown in FIG. As shown in FIG. 1, when the undercoat material prepared by blending the binder component and the extender pigment in the blending ratio according to the present invention is applied, the undercoat material having good adhesion and high tensile strength is obtained. It was found that a coating film was formed. In addition, a test plate with the same coating as these was separately prepared, and the chipping resistance was examined by colliding the gravel against the surface. When the undercoat material was applied, there was no occurrence of large scratches and no peeling of the coating film, and the results showed much better results as compared with those having other compounding ratios. The above evaluation was performed by the following method. (1) Evaluation of Adhesion At approximately the center of the test plate, 11 parallel vertical and horizontal lines each reaching the substrate with a cutter knife are drawn at intervals of 2 mm at regular intervals to form a square mesh. A cellophane tape having a width of about 18 mm to 30 mm was closely adhered to the burd-grained coating film, peeled upward at a stretch, and the number of the rags remaining without being peeled, and the state of the peeled part and the scratches were observed.
The value shown in is the total number of rumens remaining without peeling. (2) Tensile strength test a) Apparatus: tensile tester b) Test piece shape: dumbbell-shaped No. 3 shown in FIG. 3 c) Test conditions: (a) Temperature 5-35 ° C., relative humidity 45-85% And (B) The moving speed of the gripper is 200 mm
/ Min d) Indication: The test machine is operated under the above conditions, and the maximum load when the test piece is cut is measured and calculated by the following formula. T _B = F _B / A T _B : Tensile strength F _B : Maximum load (N) A: Cross-sectional area (m ² ) of test piece before test The room temperature drying type undercoat material of the present invention is characterized by containing 150 to 250 parts by weight of an extender pigment based on 100 parts by weight of a binder component composed of a synthetic rubber latex and / or a synthetic resin emulsion. It can be applied with good adhesiveness even on the surface of a highly water-repellent base material with stable physical properties and can exhibit excellent chipping resistance. Can be suitably used as an undercoat by further painting. In such an undercoat material, when the binder component is composed of a styrene-butadiene rubber and a (meth) acrylate polymer and the extender is talc, the adhesion and chipping resistance of the obtained film are improved. The properties such as sex become more excellent,
In particular, when applied to a fluororesin-based overcoat paint film, it can exhibit much superior properties as compared with a conventionally used undercoat material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the adhesiveness of an undercoat material coating film and the tensile strength characteristics of the coating film obtained in Examples and Comparative Examples of the present invention. FIG. 2 is a cross-sectional view schematically showing the configuration of a coating film according to one embodiment of the present invention. FIG. 3 is a drawing showing a shape of a test piece used for a tensile strength test in an example of the present invention. [Description of Signs] 1 ... steel plate, 2 ... electrodeposition coating film, 3 ... intermediate coating film, 4a ... top coating base coat, 4b ... top coating clear coat (fluororesin type), 5 ... room temperature drying type undercoat coating.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C09D 133/06 C09D 133/06 201/00 201/00 (72) Inventor Hiroshi Okazaki 1-21-23 Fuchinobe, Sagamihara City, Kanagawa Prefecture No. Tokyo Chemical Coating Co., Ltd. (56) References JP-A-5-32938 (JP, A) JP-A-10-183017 (JP, A) JP-A-7-62291 (JP, A) JP-A-7- 166098 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 1/00-10/00 C09D 101/00-201/10

Claims (1)

(57) [Claim 1] Styrene-butadiene rubber and (meth)
(T) room temperature drying applied to a fluororesin topcoat paint film, characterized in that only 100 parts by weight of a binder component composed of an acrylate ester polymer and 150 to 250 parts by weight of talc are contained in water. Mold undercoat material.