JP6866133B2 - Water-based paints and coatings - Google Patents

Description

The present invention relates to water-based paints and coated materials.

It is widely practiced to coat the surface of various base materials in order to impart functionality to the surface of the base material and enhance the appearance. For example, in order to improve wear resistance and the like, weather strips for automobiles are generally coated with a curable silicone-based paint or a curable urethane-based paint on the surface.

From the viewpoint of environmental issues and safety and health, such paints for automobile weather strips are shifting from organic solvent type paints to water-based paints, and various water-based paints have been developed (). For example, see Patent Documents 1 and 2). In today's world where higher quality is required, there is a demand for water-based paints that can impart higher wear resistance and the like than conventional water-based paints.

On the other hand, cellulose nanofibers produced from pulp, which is a cellulosic raw material, by chemical treatment, pulverization, etc., are excellent in strength, elasticity, thermal stability, etc., and are therefore expected to be used in various industrial applications. It has also been proposed to be used as an additive to water-based paints (see, for example, Patent Document 3). However, the technique described in the above publication is based on the use of cellulose nanofibers in a water-based paint for coatability, storage stability, corrosion resistance, etc., and does not take into consideration wear resistance and the like.

Japanese Unexamined Patent Publication No. 2001-207106 Japanese Unexamined Patent Publication No. 2001-207113 Japanese Unexamined Patent Publication No. 2009-67710

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a water-based paint capable of imparting high wear resistance, and a coated product using such a water-based paint. To do.

The present invention made to solve the above problems is a water-based coating material containing a resin, cellulose fibers and water, wherein the cellulose fibers are 5 μm or more in a volume-based pseudo particle size distribution curve measured by a laser diffraction method. It is characterized by containing the first fiber having the most frequent value in the range of 25 μm or less.

According to the water-based paint, the abrasion resistance of the coating film can be enhanced by containing the cellulose fiber having such a size. The reason for this is not clear, but it is presumed that the presence of the fine first fibers causes the dense layers to be formed with high adhesion, resulting in increased wear resistance. Further, by containing such a first fiber, the slipperiness of the coating film can be enhanced.

The content of the first fiber with respect to 100 parts by mass of the resin is preferably 1 part by mass or more and 50 parts by mass or less. By setting the content of the first fiber in the above range, the abrasion resistance of the obtained coating film can be further enhanced.

The resin preferably contains a curable urethane resin. By using the curable urethane resin, the abrasion resistance and the like of the obtained coating film can be further improved.

It is preferable that the cellulose fiber further contains a second fiber having a mode value in the range of 50 μm or more in the volume-based pseudo particle size distribution curve measured by the laser diffraction method. By further containing the second fiber having such a size, the slipperiness of the coating film can be enhanced. The reason for this is not clear, but it is presumed that the presence of the second fiber, which has a relatively large size, increases the slipperiness by forming appropriate irregularities on the surface.

The water-based paint is suitably used for surface coating of weather strips for automobiles. According to the water-based paint, by containing the cellulose fiber, high abrasion resistance and slipperiness can be imparted to the weather strip for automobiles. The reason for this is not clear, but it is presumed that the cellulose fibers improve the adhesion between the weather strip body and the coating film, and form appropriate irregularities on the surface to improve slipperiness.

Another invention made to solve the above problems is a coating product comprising a base material and a coating film laminated on the surface of the base material, wherein the coating film is formed from the water-based paint. It is characterized by being. According to the coated product, since the coating film is formed from the above-mentioned water-based paint, good wear resistance and the like can be exhibited.

As described above, according to the present invention, it is possible to provide a water-based paint capable of imparting high wear resistance, and a coated product using such a water-based paint.

It is a figure which shows the outline of the Gakushin type wear tester used for the wear resistance test in an Example.

Hereinafter, the water-based paint and the coated product according to the embodiment of the present invention will be described in detail in order.

<Water-based paint>
The water-based paint according to the embodiment of the present invention is a water-based paint containing resin, cellulose fibers and water, and the cellulose fibers are 5 μm or more and 25 μm or less in a volume-based pseudo particle size distribution curve measured by a laser diffraction method. Contains the first fiber having the most frequent value in the range of.

(resin)
The resin contained in the water-based paint is preferably a water-based resin that can be dissolved and / or dispersed in water or an aqueous medium containing water as a main component. Examples of such resins include water-based acrylic resins, water-based curable acrylic resins, water-based curable urethane resins, water-based acrylic urethane resins, water-based vinyl chloride resins, water-based vinyl acetate resins, water-based epoxy resins, and water-based alkyds. Generally used water-based resins such as water-based resins, water-based polyamide-based resins, water-based cellulose-based resins, and water-based silicones can be used. Further, a synthetic polymer emulsion can be used as the resin.

Examples of synthetic polymer emulsions include styrene-butadiene-based copolymer latex, polystyrene-based polymer latex, polybutagen-based polymer latex, acrylonitrile-butagen-based copolymer latex, polyurethane-based polymer latex, and polymethylmethacrylate-based weight. Combined latex, methyl methacrylate-butagen-based copolymer latex, polyacrylate-based polymer latex, vinyl chloride-based polymer latex, vinyl acetate-based polymer emulsion, vinyl acetate-ethylene-based copolymer emulsion, polyethylene emulsion, carboxy-modified styrene Examples thereof include a butadiene copolymer resin emulsion, an acrylic resin emulsion, and an aqueous silicone polymer latex.

Above all, it is preferable to use an aqueous curable urethane resin as the resin. By using the curable urethane resin, the abrasion resistance and the like of the obtained coating film can be further improved.

The curable urethane resin is a polymer prepared by using a polyol compound, a compound having an active hydrogen group and a hydrophilic group in the molecule, an organic polyisocyanate, and if necessary, a chain extender and a polymerization terminator, and the polymer is prepared in water. It is obtained by dissolving or dispersing in.

The polyol compound is not particularly limited as long as it contains two or more hydroxyl groups, and is, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, and glycerin. Polyhydric alcohols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc. Polyether polyols; dicarboxylic acids such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, phthalic acid, isophthalic acid and ethylene glycol, Polyester polyols obtained from glycols such as triethylene glycol, propylene glycol, butylene glycol, tripropylene glycol, neopentyl glycol; polycaprolactone polyol; polybutadiene polyol; polycarbonate polyol; polythioether polyol; and the like. The above-mentioned polyol compound may be used alone, or two or more kinds may be used in combination.

Compounds having an active hydrogen group and a hydrophilic group in the molecule include active hydrogen and an anion group {an anion group or an anion forming group (which reacts with a base to form an anion group, and in this case, a urethanization reaction). Known as a compound containing (converted to an anionic group by neutralizing with a base before, during or after)} (for example, α, α-dimethylol propionic acid, α, α-dimethylol butyric acid, etc.), in the molecule Examples thereof include those known as compounds having an active hydrogen and a cationic group and those known as a compound having an active hydrogen and a nonionic hydrophilic group in the molecule (for example, polyethylene glycol, alkyl alcohol alkylene oxide adduct, etc.).

The organic polyisocyanate is not particularly limited as long as it has two or more isocyanate groups in the molecule, and is, for example, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-. Trimethylhexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexyl-2,4-diisocyanate, methylcyclohexyl-2,6-diisocyanate, xylylene Isocyanates, aliphatic diisocyanates such as 1,3-bis (isocyanate) methylcyclohexane, tetramethylxylylene diisocyanate, transcyclohexane-1,4-diisocyanate, lysine diisocyanate, 2,4-toluylene diisocyanate, 2,6-tolui Range isocyanate, diphenylmethane-4,4'-diisocyanate, 1,5'-naphthendiisocyanate, trizine diisocyanate, diphenylmethylmethane diisocyanate, tetraalkyldiphenylmethanediisocyanate, 4,4'-dibenzyldiisocyanate, 1,3-phenylenediocyanate, etc. Aromatic diisocyanates, lysine ester triisocyanates, triphenylmethane triisocyanates, 1,6,11-undecantriisocyanates, 1,8-diisocyanates-4,4-isocyanate methyloctanes, 1,3,6-hexamethylene triisocyanates , Triisocyanates such as bicycloheptane triisocyanate and the like. Further, it may be used as a dimer or trimmer (isocyanurate bond) of these polyisocyanate compounds, or may be used as a biuret by reacting with an amine. Further, a polyisocyanate having a urethane bond obtained by reacting these polyisocyanate compounds with a polyol can also be used.

It is more preferable to use an aliphatic diisocyanate as the organic polyisocyanate. By preparing a curable urethane resin using an aliphatic diisocyanate, the water resistance of the obtained coating film can be adjusted within an appropriate range.

The chain extender that may be added if necessary during the preparation of the curable urethane resin is not particularly limited as long as it contains two or more active hydrogen groups, and examples thereof include low molecular weight polyols, polyamines, and water.

Examples of the low molecular weight polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 3-methylpentanediol, 2-ethyl-1,3-hexanediol, and trimethylolpropane.

Examples of the polyamine include ethylenediamine, hexamethylenediamine, diethylenetriamine, hydrazine, xylylenediamine, isophoronediamine and the like.

Examples of the polymerization terminator include a compound having one active hydrogen in the molecule or a monoisocyanate compound.

Examples of the compound having one active hydrogen in the molecule include monoalcohol (for example, alkyl alcohol such as methanol, butanol and octanol, alkyl alcohol alkylene oxide adduct, etc.) or monoamine (for example, butylamine, dibutylamine and the like). Alcohol amines, etc.).

Examples of the monoisocyanate compound include methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, lauryl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, and tolyrene isocyanate.

The reaction method for producing a curable urethane resin is a one-shot method in which each component is reacted at once or a multi-step method in which each component is reacted stepwise {a part of an active hydrogen-containing compound (for example, a polymer polyol) and polyisocyanate are used. Any method may be used, which is a method of reacting to form an NCO-terminal prepolymer and then reacting the rest of the active hydrogen-containing compound to produce the compound. The synthetic reaction of the curable urethane resin is usually carried out at 40 to 140 ° C., preferably 60 to 120 ° C. In order to accelerate the reaction, a tin-based catalyst such as dibutyltin laurate or tin octylate or an amine-based catalyst such as triethylenediamine, which is used in a normal urethanization reaction, may be used. Further, the above reaction may be carried out in an organic solvent inert to isocyanate (for example, acetone, toluene, dimethylformamide, etc.), and the solvent may be added during or after the reaction.

The curable urethane resin according to the present embodiment has a known method (in the case of an anion-forming group, a method of neutralizing with a base to form an anion group, and in the case of a cation-forming group, a cation group is formed by a quaternizing agent. It is preferably obtained by treating with a method for forming or a method for forming a cationic group by neutralizing with an acid) and then dissolving in water.

The step of dissolving in water is not particularly limited, and the step may be after the above reaction or in the middle of the multistep method. For example, when dissolved in water at the stage of NCO-terminated prepolymer, an aqueous curable urethane resin can be obtained by dissolving in water while extending the chain with water and / or polyamine.

When an organic solvent inert to isocyanate is used, the solvent may be removed after being dissolved in water.

As the water-based curable urethane resin, in addition to being prepared by the above procedure, known commercially available products can be preferably used.

(Cellulose fiber)
Cellulose fiber is a fiber obtained from a plant material such as pulp (pulp fiber). Examples of pulp used as a raw material for cellulose fibers include broad-leaved kraft pulp (LKP) such as broad-leaved bleached kraft pulp (LBKP) and broad-leaved unbleached kraft pulp (LUKP), coniferous bleached kraft pulp (NBKP), and coniferous unbleached kraft pulp (LBKP). Chemical pulp such as coniferous kraft pulp (NKP) such as NUKP);
Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Mechanical pulp such as Chemi-Thermo Mechanical Pulp (CTMP), Bleached Thermo-Mechanical Pulp (BTMP);
Used paper pulp manufactured from used tea paper, kraft envelope used paper, magazine used paper, newspaper used paper, leaflet used paper, office used paper, cardboard used paper, upper white used paper, Kent used paper, imitation used paper, ground ticket used paper, sashimi used paper, etc.;
Examples thereof include deinked pulp (DIP) obtained by deinking used paper pulp. These may be used alone or in combination of a plurality of types as long as the effects of the present invention are not impaired.

Other plant raw materials include pulp obtained from linter pulp, hemp, bagasse, kenaf, esparto grass, bamboo, paddy husks, straw and the like. Further, wood, hemp, bagasse, kenaf, esparto grass, bamboo, rice husk, straw and the like, which are raw materials for pulp, can be directly used as raw materials for plants.

The cellulose fiber of the water-based paint according to the present embodiment contains the first fiber having the mode in the range of 5 μm or more and 25 μm or less in the volume-based pseudo particle size distribution curve measured by the laser diffraction method. By containing the first fiber of the size, the abrasion resistance of the coating film can be enhanced. Further, by containing such a first fiber, the slipperiness of the coating film can be enhanced. The "pseudo-particle size distribution curve" is a volume standard measured for a dispersion liquid dispersed in water as a dispersion medium and ultrasonically treated using a particle size distribution measuring device "LA-960S" manufactured by HORIBA, Ltd. as a particle size distribution measuring device. It means a curve showing a particle size distribution.

The first fiber having the above size is in the state of cellulose fine fibers having a fiber width of nano size (1 nm or more and 1000 nm or less), and is generally called cellulose nanofiber. The first fiber, that is, the cellulose nanofiber, preferably has one peak in the pseudo particle size distribution curve measured by the laser diffraction method in the water-dispersed state. Cellulose nanofibers having a single peak have been sufficiently miniaturized, and can more exert the effect of improving wear resistance.

Cellulose nanofibers can usually be obtained by defibrating a plant raw material (fiber raw material) by a known method. Hereinafter, a method for producing cellulose nanofibers when pulp is used as a plant raw material will be described, but cellulose nanofibers can also be obtained by the same method when using a plant raw material other than pulp.

The method for producing cellulose nanofibers is not particularly limited as long as the effects of the present invention are not impaired, and known methods can be used. For example, the pulp in an aqueous dispersion state may be subjected to defibration by mechanical treatment, or may be subjected to defibration by chemical treatment such as enzyme treatment or acid treatment, but it is preferable to defibrate by mechanical treatment. .. By defibrating the pulp by mechanical treatment, cellulose nanofibers can be obtained more easily and reliably. Further, the heat resistance of the cellulose nanofibers can be enhanced by obtaining the cellulose nanofibers by a method that does not involve acid denaturation.

Examples of the defibration method by mechanical treatment include a grinder method for grinding pulp between rotating grindstones, an opposed collision method using a high-pressure homogenizer, and a pulverization method using a ball mill, a roll mill, a cutter mill, and the like. Usually, the defibration treatment is repeated until the cellulose nanofibers obtained by defibrating the pulp have a desired size.

The pulp may be subjected to preliminary beating before defibration. The pre-beating (mechanical pretreatment) is not particularly limited, and a known method can be used. As an example of a specific method, it is preferable to proceed with defibration step by step. In particular, the grinding method, etc., in which unbeaten raw material pulp is pre-beaten to 30% or less of the starting raw material in advance using a so-called beating facility such as a naigara beater, and then ground between rotating grindstones. It is preferable to carry out the defibration treatment until cellulose nanofibers are obtained.

In addition, the pulp may be chemically pretreated before defibration. Examples of this chemical pretreatment include hydrolysis treatment using an acid such as sulfuric acid or an enzyme. By applying the chemical pretreatment in this way, cellulose nanofibers can be efficiently obtained by mechanical or chemical defibration treatment.

The water retention of the cellulose nanofibers is preferably 250% or more and 500% or less, for example. If the water retention level is less than the above lower limit, the cellulose nanofibers may not be sufficiently finely divided. On the other hand, if the water retention level exceeds the above upper limit, the manufacturing cost may be too high. "Water retention (%)" is defined as JAPAN TAPPI No. It is a value measured according to 26.

The content of the first fiber (cellulose nanofiber) with respect to 100 parts by mass of the resin is preferably 1 part by mass or more and 50 parts by mass or less. As the lower limit of this content, 3 parts by mass is more preferable, and 5 parts by mass is further preferable. On the other hand, as the upper limit of this content, 30 parts by mass is more preferable. By setting the content of the first fiber to the above lower limit or more, the abrasion resistance and slipperiness of the obtained coating film can be further improved. On the other hand, by setting the content of the first fiber to the above upper limit or less, the coatability and the like can be improved.

The cellulose fiber preferably contains a second fiber having a mode in the range of 50 μm or more in the volume-based pseudo-particle size distribution curve measured by the laser diffraction method. By containing the coarse second fiber having such a size in the water-based paint, the slipperiness of the coating film can be enhanced. The reason for this is not clear, but it is presumed that the presence of the second fiber, which has a relatively large size, increases the slipperiness by forming appropriate irregularities on the surface. The method for producing the second fiber can be the same as the method for producing cellulose nanofibers, and can be produced by appropriately adjusting the defibration degree of the pulp.

The mode value of the second fiber can be present in the range of, for example, 500 μm or less, but is preferably 300 μm or less, more preferably 150 μm or less. When the second fiber has such a size, the unevenness formed on the surface becomes a more appropriate size, and the slipperiness is further enhanced. It is also possible to suppress clogging of the spray nozzle during spray application. The second fiber may have a plurality of peaks in the pseudo particle size distribution curve.

The water retention of the second fiber is preferably 150% or more and less than 250%. When it has such a high degree of water retention, it means that the second fiber has been defibrated to some extent. Therefore, by using the second fiber having such a water retention degree, the unevenness formed on the surface becomes a more appropriate size, and the slipperiness can be further improved. Further, by using the second fiber in which such sufficient defibration has progressed, the flexibility of the fiber can be increased and the decrease in the strength of the coating film can be suppressed.

It is preferable that the cellulose fiber contains the first fiber (cellulose nanofiber) and the second fiber (crude fiber) at the same time. By containing two types of cellulose fibers having different sizes, both abrasion resistance and slipperiness can be satisfactorily improved. The reason for this is not clear, but the presence of fine cellulose nanofibers forms a dense layer with high adhesion, resulting in increased wear resistance and the presence of relatively large crude fibers, which makes it suitable for the surface. It is presumed that this is due to the fact that the slipperiness is enhanced by the formation of various irregularities.

The volume-based pseudo-particle size distribution curve measured by the laser diffraction method of the cellulose fiber has a peak (a) observed in the range of 5 μm or more and 25 μm or less and a peak (b) observed in the range of 50 μm or more. It is preferable to have. Even with such a water-based paint, by containing two types of fibers having different sizes, both wear resistance and slipperiness can be satisfactorily improved.

As a mixing ratio when the first fiber (cellulose nanofiber) and the second fiber (crude fiber) are contained, the first fiber (the first fiber ( Cellulose nanofibers) are preferably 10 to 90 parts by mass. By setting the mixing ratio of the first fiber and the second fiber within the above range, it is possible to improve both wear resistance and slipperiness. In order to particularly enhance the abrasion resistance, the content of the first fiber with respect to 100 parts by mass of all cellulose fibers may be 50 parts by mass or more, 70 parts by mass or more, and 90 parts by mass or more. It may be there. Further, by suppressing the mixing ratio of the second fibers (crude fibers) in this way, it is possible to suppress the occurrence of clogging in the nozzle, for example, during spray application.

The content of the entire cellulose fiber with respect to 100 parts by mass of the resin is preferably 1 part by mass or more and 50 parts by mass or less. As the lower limit of this content, 3 parts by mass is more preferable, and 5 parts by mass is further preferable. On the other hand, as the upper limit of this content, 30 parts by mass is more preferable. By setting the content of the entire cellulose fiber to the above lower limit or more, the abrasion resistance and slipperiness of the obtained coating film can be further improved. On the other hand, by setting this content to the above upper limit or less, the coatability and the like can be improved.

The content of the carboxy group of the cellulose fiber is preferably 0.1 mmol / g or less. Some cellulose nanofibers are subjected to a modification treatment such as acid modification during production. However, since the heat resistance of the acid-modified cellulose nanofibers is lowered due to the presence of the carboxy group, it is preferable that the acid-modified treatment is not performed from the viewpoint of heat resistance. Therefore, when the content of the carboxy group of the cellulose fiber is 0.1 mmol / g or less, the heat resistance can be enhanced. When the content of the carboxy group of the cellulose fiber is 0.1 mmol / g or less, sufficient heat resistance can be exhibited even when heated to, for example, about 200 to 250 ° C.

(Other ingredients)
The water-based paint of the present embodiment may contain other components in addition to the above components, if necessary. Other components include, for example, pigments, other aqueous resins, film-forming aids, surface conditioners, preservatives, fungicides, defoamers, light stabilizers, UV absorbers, antioxidants, pH adjusters, etc. Can be mentioned.

(Preparation method of water-based paint)
The method for preparing the water-based paint is not particularly limited, and the water-based paint can be prepared by mixing the above-mentioned components and stirring with a stirrer or the like. When the first fiber and the second fiber are used, the separately produced first fiber and the second fiber can be mixed at a desired mixing ratio. Depending on the dispersibility of each component, in addition to a stirrer, a vehicle containing water, a surfactant, a dispersant, or the like, which has been pre-dispersed using a sand grind mill or the like, may be added.

<Coated material>
The coated product according to another embodiment of the present invention is a coated product including a base material and a coating film laminated on the surface of the base material, and the coating film is formed from the water-based paint. It is characterized by being. According to the coated product, since the coating film is formed from the above-mentioned water-based paint, good wear resistance and the like can be exhibited.

The base material to which the water-based paint of the present embodiment is applied is not particularly limited, and for example, metal base materials such as iron, stainless steel and its surface-treated products, cement base materials such as gypsum, polyesters, acrylics and the like. Examples include a plastic base material. In addition, various coating materials for construction such as building materials and structures made of these base materials, various coating materials for the automobile industry such as automobile bodies and parts, and various coating materials in the industrial field such as electrical appliances and electronic parts. Can be mentioned. Further, the water-based paint can be applied at the time of remodeling each of the above-mentioned objects to be coated.

Automotive weather strips are usually made of an elastomer (EPDM rubber), which is a copolymer of ethylene, propylene and a small amount of diene, which is non-polar and hydrophobic. With respect to such EPDM rubber, the water-based paint can form a coating film having excellent wear resistance and the like.

The method for producing a coated product using the water-based paint is not particularly limited in terms of the coating method and drying conditions, and generally well-known ones can be applied. Further, the water-based paint can be used for various purposes, but the conditions from normal temperature drying to heat drying are particularly preferable. The heat drying usually means drying by heating up to about 80 ° C., but may be, for example, drying by heating up to about 250 ° C.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Evaluation method>
Various physical properties of Examples and Comparative Examples were measured according to the following evaluation methods.

(Pseudo particle size distribution curve)
In accordance with ISO-13320 (2009), a particle size distribution measuring device "LA-960S" manufactured by HORIBA, Ltd. was used as a particle size distribution measuring device to measure a dispersion liquid dispersed in water as a dispersion medium and sonicated. Obtained the most frequent diameter. The "mode" measured here corresponds to the mode value of the pseudo particle size distribution curve described above.

[Example 1]
(Preparation of cellulose fiber)
The raw material pulp (bleached thermomechanical pulp (BTMP): 98% by mass of water content) was pre-beaten over 2 hours and 30 minutes using a Niagara beater. Next, defibration treatment using a stone mill type disperser ("Super Mass Colloider" of Masuyuki Sangyo Co., Ltd.) was performed three times and concentrated with a centrifuge to obtain an aqueous dispersion (concentration) of cellulose nanofibers as the first fiber. 14.7% by mass) was obtained. The first fiber (cellulose nanofiber) contained in this aqueous dispersion had one peak in the pseudo particle size distribution of the particle size distribution measurement using laser diffraction, and the mode was 20 μm.

(Preparation of water-based paint)
A water-based paint was prepared by dispersing 100 parts by mass of a water-based curable urethane resin solution and 2 parts by mass of the first fiber (cellulose nanofiber) in 160 parts by mass of water. The solid content concentration in the water-based paint was 14% by mass. The content of the first fiber (cellulose nanofiber) with respect to 100 parts by mass of the curable urethane resin was 6 parts by mass.

[Comparative Example 1]
A water-based paint was prepared in the same manner as in Example 1 except that the first fiber (cellulose nanofiber) was not blended in the preparation of the water-based paint.

<Evaluation>
(Abrasion resistance test)
The wear resistance was tested using a Gakushin wear tester (stroke: 150 mm, speed: 60 times / minute) equipped with the glass wear element (t = 3.5 mm) for the wear resistance test shown in FIG. The number of times when the coated surface of the evaluation coating sample was worn or peeled off and the base material was exposed was investigated. The larger the number of times, the better the wear resistance of the paint. The evaluation coating sample was prepared by applying a water-based paint on a sponge as a base material so that the thickness after drying became a specified value, and then drying in a ventilation oven. The evaluation results are shown in Table 1.

(Slipperiness test)
The coefficient of static friction and the coefficient of dynamic friction were determined by the following procedure. Using a Haydon tester (HEIDON TRIBOGEAR TYPE32, stylus: glass watch glass, load: 20N), after sliding twice at a sliding speed of 1000 mm / min, the measured value obtained by sliding the third time was obtained. .. The smaller these coefficients are, the better the slipperiness of the paint is. The evaluation coating sample was prepared by applying a water-based paint on a sponge as a base material so that the thickness after drying became a specified value, and then drying in a ventilation oven. The evaluation results are shown in Table 1.

As shown in Table 1, in Example 1, the abrasion resistance and slipperiness of the obtained coating film were better than those in Comparative Example 1.

[Examples 2 to 5, Comparative Example 2] (Confirmation of combined effect)
Raw material pulp (wide-leaved bleached kraft pulp): 98% by mass of water content) was beaten for 2 hours and 30 minutes using a Niyagara beater, and concentrated with a centrifuge to measure the particle size distribution using laser diffraction. A second fiber (concentration 11.2% by mass) having three peaks in the pseudo particle size distribution and having a most frequent value of 74 μm was obtained. JAPAN TAPPI No. The water retention of the second fiber measured according to 26 was 200%.

A coating material using the first fiber (cellulose nanofiber) and the second fiber (crude fiber) in combination or only one of them was prepared so as to have the compounding ratio shown in Table 2. Specifically, 100 parts by mass of the water-based curable urethane resin solution and 10 parts by mass of the total mass of the first fiber and the second fiber were dispersed in 160 parts by mass of water to prepare a water-based paint. The solid content concentration in the water-based paint was 16% by mass. The total content of the first fiber and the second fiber with respect to 100 parts by mass of the curable urethane resin was 29 parts by mass.

A wear resistance test and a slipperiness test were performed in the same manner as described above. The results are shown in Table 2. The results of Comparative Example 1 are also shown in Table 2.

Table 2 suggests that the optimum balance between wear resistance and slipperiness can be achieved by using the first fiber and the second fiber in combination.

The coating film obtained by the water-based paint of the present invention has good adhesion to EPDM rubber and excellent wear resistance without pretreatment such as undercoating, and is most suitable as a paint for weather strips for automobiles. is there.

Claims (7)

A water-based paint containing resin, cellulose fibers and water.
The cellulose fiber contains the first fiber having the mode in the range of 5 μm or more and 25 μm or less in the volume-based pseudo particle size distribution curve measured by the laser diffraction method .
A water-based coating material, wherein the cellulose fibers further contain a second fiber having a mode in the range of 50 μm or more in a volume-based pseudo-particle size distribution curve measured by a laser diffraction method. A water-based paint containing resin, cellulose fibers and water.
The cellulose fiber contains the first fiber having the mode in the range of 5 μm or more and 25 μm or less in the volume-based pseudo particle size distribution curve measured by the laser diffraction method.
A water-based paint characterized by being used for surface coating of weather strips for automobiles. The water-based coating material according to claim 1 or 2 , wherein the content of the first fiber with respect to 100 parts by mass of the resin is 1 part by mass or more and 50 parts by mass or less. The water-based paint according to claim 1, claim 2 or claim 3 , wherein the resin contains a curable urethane resin. A coated product comprising a base material and a coating film laminated on the surface of the base material.
A coated product, wherein the coating film is formed from the water-based paint according to any one of claims 1 to 4. The water-based paint according to claim 1, which is used for surface coating of weather strips for automobiles. The water-based coating material according to claim 2, wherein the cellulose fibers further contain a second fiber having a mode in the range of 50 μm or more in a volume-based pseudo-particle size distribution curve measured by a laser diffraction method.

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