CN111936565B

CN111936565B - Coated body

Info

Publication number: CN111936565B
Application number: CN201980023663.6A
Authority: CN
Inventors: 小林稔幸; 井上贵公; 山田晃司; 渡边淳也
Original assignee: Dai Nippon Toryo KK
Current assignee: Dai Nippon Toryo KK
Priority date: 2018-03-30
Filing date: 2019-03-19
Publication date: 2022-01-04
Anticipated expiration: 2039-03-19
Also published as: JP6701582B2; CN111936565A; MX2020010175A; WO2019188574A1; JP2019178214A

Abstract

The invention provides a coated body having a coating film with good scratch resistance and chemical resistance. The coated body comprises a plastic substrate and a coating film formed on the surface of the plastic substrate, wherein the coating film satisfies the following conditions (1) and (2): (1) the glass transition temperature of the coating film is above 30 ℃; (2) the Young's modulus of the coating film is 1000N/mm2 or less, and the elongation of the coating film is 80% or more. In the coated body, the coating composition is adjusted so that the glass transition temperature of the coating film and the Young's modulus of the coating film satisfy predetermined numerical conditions, and the coating film formed on the coated body is a coating film having both scratch resistance and chemical resistance.

Description

Coated body

Technical Field

The present invention relates to a coated body having a plastic substrate and a coating film formed on a surface thereof, and particularly to a self-repairing coated body for use in automotive interior.

Background

Plastic molded articles are molded articles of polymers having plasticity, and are used for mobile phones, household appliances, office equipment, automobile interior parts, and the like, and the surfaces of these plastic molded articles are sometimes coated to be decorated or provided with functions. As a coating material for coating a plastic molded article (coating material for plastic), in addition to the purpose of decoration, depending on the use of the plastic molded article, it is sometimes necessary to impart functions such as scratch resistance, abrasion resistance, discoloration resistance, sebum resistance, high gloss, high weather resistance, and electrical insulation to a coating film.

As a coating composition having scratch resistance and mainly used for forming a coated body for automobile interior, for example, patent document 1 discloses a self-repairing coating composition obtained by reacting a polyisocyanate, an acrylic polyol and a polycarbonate polyol. The self-healing coating composition described in patent document 1 has excellent self-healing performance against scratches of a coating film, and also has good transparency, smoothness, and ultimate strength of the coating film.

Further, patent document 2 discloses a coating material for a soft coating film, which contains fine particles having a particle diameter of 1 to 300 nm. The coating material for a soft coating film containing fine particles described in patent document 2 has excellent scratch resistance, maintains inherent characteristics of the soft coating material such as difficulty in occurrence of cracks, and has excellent stain resistance and chemical resistance.

Prior Art

Patent document

Patent document 1: japanese laid-open patent publication No. 2016-108347

Patent document 2: japanese laid-open patent publication No. 2010-189477

Disclosure of Invention

Here, in recent years, plastic molded articles (for example, exterior parts of cellular phones or interior parts of automobiles) which are in contact with human skin and hands for a long time are required to have excellent chemical resistance such as sweat resistance, lactic acid resistance, hand cream resistance, and sun cream resistance. However, such chemical resistance tends to decrease for a coating film having excellent self-repairing properties. In addition, the soft coating paint containing fine particles of patent document 2 has a problem that sweat and chemical substances gradually permeate into the interface between the fine particles and the resin, and the coating components deteriorate with time.

The present invention has been made in view of the above problems, and an object thereof is to provide a coated body having a coating film which has both good scratch resistance and good chemical resistance.

Means for solving the problems

In view of the above problems, the present inventors have conducted earnest studies. As a result, they have found that the above problems can be solved by adjusting the coating composition so that the glass transition temperature of the coating film and the young's modulus of the coating film satisfy predetermined numerical conditions. Specifically, the present invention provides the following embodiments.

[1] A coated body comprising a plastic substrate and a coating film formed on a surface of the plastic substrate, wherein the coating film satisfies the following conditions (1) and (2):

(1) the glass transition temperature of the coating film is above 30 ℃;

(2) the Young's modulus of the coating film is 1000N/mm2 or less, and the elongation of the coating film is 80% or more.

[2] The coated body according to the above [1], wherein the coating film has two or more glass transition temperatures, and an average value of the glass transition temperatures is 30 ℃ or more and 60 ℃ or less.

[3] The coated body according to the above [1] or [2], wherein the coating film has an inter-crosslinking molecular weight of 700 to 1200.

[4] The coated body according to any one of the above [1] to [3], wherein the coating film is formed from a self-healing coating material containing a main agent containing at least the following (a) and (B) as hydroxyl group-containing components and the following curing agent (C);

(A) a polycarbonate diol having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less; and

(B) a resin component other than the component (A) having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less;

(C) an isocyanate curing agent.

[5] The coated body according to [4] above, wherein the ratio (B)/(A) of the hydroxyl group value of the component (A) to the hydroxyl group value of the component (B) is 0.5 to 1.5.

[6] The coated body according to the above [4] or [5], wherein the component (B) is at least one selected from the group consisting of acrylic polyol, polyester polyol and polyether polyol.

[7] The coated body according to any one of the above [4] to [6], wherein the component (A) has a weight average molecular weight of 500 or more and 2000 or less, and the component (B) has a weight average molecular weight of 5000 or more and 100000 or less.

[8] The coated body according to any one of the above [4] to [7], wherein the amount of the component (B) is 40 to 150 parts by mass based on 100 parts by mass of the component (A).

[9] The coated body according to any one of the above-mentioned embodiments [4] to [8], wherein the total amount of the component (A) and the component (B) is 70% by mass or more based on the hydroxyl group-containing component.

[10] The coated body according to any one of the above [1] to [9], wherein the coating film formed on the surface of the plastic substrate does not contain inorganic fine particles having a particle diameter of 1nm to 300nm, except for the coloring material.

Effects of the invention

The coated body of the present invention is a coated film having both scratch resistance and chemical resistance, which is formed on the coated body, by adjusting the coating composition so that the glass transition temperature of the coated film and the young's modulus of the coated film satisfy predetermined numerical conditions.

Detailed Description

The present invention will be described in detail below

< coating body >

The coated body of the present invention has a plastic substrate and a coating film formed on the surface of the plastic substrate. Here, the number of the first and second electrodes,

the coating film satisfies the following conditions (1) and (2).

(1) The glass transition temperature of the coating film is above 30 ℃;

Glass transition temperature

As described above, the coated body of the present invention has a glass transition temperature of a coating film of 30 ℃. When the glass transition temperature of the coating film is 30 ℃ or higher, the chemical resistance of the coating film is improved. Further, although it can be observed that the glass transition temperature of the coating film is two or more, in this case, an average value of two or more glass transition temperatures may be used as the glass transition temperature of the coating film. In the present invention, the coating film preferably has two or more glass transition temperatures. The glass transition temperature of the coating film is preferably 30 ℃ or higher and 60 ℃ or lower, and more preferably 30 ℃ or higher and 50 ℃ or lower. Since the glass transition temperature of the coating film is set to be within the above range, chemical resistance and scratch resistance of the coating film can be favorably satisfied.

Young's modulus

The Young's modulus of the coating film of the coated body of the present invention is 1000N/mm2 or less. When the young's modulus of the coating film satisfies this condition, the flexibility of the coating film becomes excellent, the self-repairability of scratches on the coating film becomes good, and the scratch resistance of the coating film becomes good. The Young's modulus of the coating film was measured at 23 ℃ according to the static Young's modulus measuring method of JIS Z2280. The Young's modulus of the coating film is preferably 50N/mm2 or more and 500N/mm2 or less, more preferably 85N/mm2 or more and 255N/mm2 or less. Since the young's modulus of the coating film is in the above range, chemical resistance and scratch resistance of the coating film can be favorably satisfied.

Elongation percentage

The coated body of the present invention has a coating film elongation of 80% or more. When the elongation of the coating film satisfies this condition, the flexibility of the coating film becomes excellent, the self-repairing property of scratches on the coating film becomes good, and the scratch resistance of the coating film becomes good. Further, the elongation of the coating film was measured at 23 ℃ according to the method for measuring the cut elongation of JIS K6251. The elongation of the coating film is preferably 85% or more and 150% or less, and more preferably 95% or more and 125% or less. Since the elongation of the coating film is within the above range, chemical resistance and scratch resistance of the coating film can be favorably satisfied.

Molecular weight between crosslinks

The coating film of the coated body of the present invention preferably has an intercrosslinking molecular weight of 700 to 1200 inclusive, and more preferably 750 to 1000 inclusive. Further, the inter-crosslinking molecular weight is obtained by dividing the number average molecular weight of the polymer constituting the coating film by the number of crosslinking functional groups. By setting the molecular weight between crosslinks within the above range, chemical resistance and scratch resistance of the coating film can be favorably achieved.

The dry film thickness of the coating film formed on the coated body of the present invention is not particularly limited as long as the chemical resistance and scratch resistance of the coating film can be satisfactorily achieved, but from the viewpoint of satisfactorily achieving both the adhesion to the substrate and the coating property, the dry film thickness is preferably 10 μm or more and 50 μm or less, and more preferably 20 μm or more and 40 μm or less.

< self-repairing coating composition >

The coating film of the coated article of the present invention has a predetermined glass transition temperature, Young's modulus and elongation, and such a coating film can be usually obtained by adjusting the glass transition temperature and crosslinking density of the resin component for forming the coating film. As the self-healing type coating material for forming the coating film of the present invention, although a polyurethane coating material is preferably used, as an example, a self-healing type coating material containing at least (a) and (B) described below as a main agent containing a hydroxyl group component and (C) may be used.

(A) A polycarbonate diol having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less;

(C) an isocyanate curing agent.

Component (A)

The component (A) is a polycarbonate diol having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less, and preferably has a glass transition temperature of-100 ℃ or less and 0 ℃ or more. A coating film using such a polycarbonate diol has excellent elasticity, and a coating film having excellent self-repairing properties can be formed by using the coating film.

The polycarbonate diol used in the present invention is generally a compound obtained by a polycondensation reaction of a known diol and a carbonylating agent. Specifically, for example, there may be mentioned: "plain CD205 PL", "plain CD 210", "plain CD220 PL" manufactured by Daicel Chemical Industries, Ltd; "ETERNACOLL UH-50", "ETERNACOLL UH-100", "ETERNACOLL UH-200", "ETERNACOLL UH-300", "ETERNACOLL UHC 50-200", "ETERNACOLL UHC 50-100", "ETERNACOLL UC-100", "ETERNACOLL UM-90", manufactured by Ube Industries, Ltd; "Duranor T5652", "Duranor T5651J", "Duranor T5650J", "Duranor 5650E", "Duranor G4672", "Duranor T4671", "Duranor T4692", "Duranor T4691", "Duranor G3450J", and the like, manufactured by Asahi Kasei corporation. These polycarbonate diols may be used alone or in combination of two or more.

The weight average molecular weight of the polycarbonate diol is preferably 500 or more and 2000 or less. By making the weight average molecular weight of the polycarbonate diol within the above range, the coating film forming performance can be improved, and the processability of the self-healing coating material can also be improved.

The hydroxyl value of the polycarbonate diol is preferably 90KOH/g or more and 200mgKOH/g or less, more preferably 100KOH/g or more and 160mgKOH/g or less. By adjusting the hydroxyl value of the resin component, the crosslinking density in the coating film can be adjusted, and chemical resistance and scratch resistance can be favorably satisfied.

Ingredient (B)

The component (B) is a resin component (polyol) having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less, and the glass transition temperature is preferably 50 ℃ or more and 120 ℃ or less. This resin component is a compound having 2 or more hydroxyl groups in1 molecule, and forms a urethane bond by reacting with an isocyanate group of a polyisocyanate in the same manner as the component (a), and since the glass transition temperature is 50 ℃ or higher and 120 ℃ or lower, it contributes to an increase in the glass transition temperature of the entire coating film, and as a result, it contributes to an increase in chemical resistance. Examples of the resin component used in the present invention include: acrylic polyol, polyester polyol, polyether polyol, hydroxyl-containing acrylic silicone resin, hydroxyl-containing fluororesin, and the like, and among these, acrylic polyol, polyester polyol, and polyether polyol are particularly preferably used. Such a resin component can be suitably obtained using a commercially available product, for example, by using a monomer having a hydroxyl group in synthesizing an acrylic resin, a polyester resin, a polyether resin, an acrylic silicone resin, or a fluororesin. The component (B) is a resin component other than the polycarbonate diol.

The weight average molecular weight of the resin component of the component (B) is preferably 5000 to 100000. By making the weight average molecular weight of the resin component within the above range, the coating film forming performance can be improved, and the processability of the self-repairing coating material can also be improved.

The hydroxyl value of the resin component of component (B) is preferably 85 to 160mgKOH/g, more preferably 100 to 150 mgKOH/g. By adjusting the hydroxyl value of the resin component, the crosslinking density in the coating film can be adjusted, and chemical resistance and scratch resistance can be achieved at the same time. For the same reason, the ratio (B)/(a) of the hydroxyl value of the component (a) to the hydroxyl value of the component (B) is preferably 0.5 or more and 1.5 or less, and more preferably 0.5 or more and 1.2 or less.

The amount of the resin component of the component (B) in the self-healing coating composition is preferably 40 parts by mass or more and 150 parts by mass or less, and more preferably 50 parts by mass or more and 120 parts by mass or less, per 100 parts by mass of the component (a). When the amount of the resin component of the component (B) is within the above range, the chemical resistance and scratch resistance of the coating film can be satisfactorily achieved.

The hydroxyl group-containing component may contain a hydroxyl group-containing resin (component (G)) other than the components (a) and (B), but the total amount of the components (a) and (B) is preferably 70% by mass or more relative to the total amount of the hydroxyl group-containing components.

Ingredient (C)

Examples of the isocyanate-based curing agent of the component (C) used in the present invention include: aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 1, 2-butylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, 2, 4, 4-or 2, 2, 4-trimethylhexamethylene diisocyanate, 2, 6-diisocyanatomethylhexanoate and the like; cycloalkylene diisocyanates such as 1, 3-cyclopentane diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 3-cyclohexane diisocyanate, 3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate, 4' -methylenebis (cyclohexyl isocyanate), methyl 2, 4-cyclohexane diisocyanate, methyl 2, 6-cyclohexane diisocyanate, 1, 4-bis (isocyanatomethyl) cyclohexane, and 1, 3-bis (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4 '-diphenyl diisocyanate, 1, 5-naphthalene diisocyanate, 4' -diphenylmethane diisocyanate, 2, 4-or 2, 6-toluene diisocyanate or a mixture thereof, 4 '-toluidine diisocyanate, diethylamine diisocyanate, and 4, 4' -diphenyl ether diisocyanate; aromatic aliphatic diisocyanates such as 1, 3-or 1, 4-xylene diisocyanate or a mixture thereof, ω' -diisocyanate-1, 4-diethylbenzene, 1, 3-or 1, 4-bis (. alpha.,. alpha. -dimethylisocyanatomethyl) benzene, and the like; triisocyanates such as triphenylmethane-4, 4', 4 ″ -triisocyanate, 1, 3, 5-triisocyanatobenzene, 2, 4, 6-triisocyanatotoluene and the like; tetraisocyanates such as 4, 4' -diphenyldimethylmethane-2, 2', 5, 5' -tetraisocyanate; further, there can be also listed: and polymeric polyisocyanates such as dimers and trimers of toluene diisocyanate, and polyphenyl polymethylene polyisocyanates. These may be used alone or in combination of two or more.

In the present invention, the blending amount of the component (C) is preferably adjusted so that the ratio of the concentration of hydroxyl groups (OH mol%) and the concentration of isocyanate groups (NCO mol%) derived from the components (a) and (B) (NCO mol%/OH mol%) is 0.9 to 1.3. When adjusted within this range, since unreacted hydroxyl groups and isocyanate groups are reduced, a coating film having good water resistance and film hardness can be obtained.

Organic solvent

The organic solvent is mainly used for dissolving the hydroxyl-containing component. As the organic solvent, a solvent widely used in the field of coating materials can be used. More specifically, there may be mentioned: aromatic hydrocarbons such as toluene, xylene, Solbesso 100 and Solbesso 150; esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; aliphatic solvents such as ethanol, ethylene glycol, acetate, and mineral spirits. They may be appropriately selected in consideration of solubility, evaporation rate, safety, and the like. The organic solvents mentioned above may be used alone or in combination of two or more.

Other ingredients

In addition to the above-mentioned components, known additives such as a crosslinking catalyst, a colorant, various pigments, a slip agent, a surface modifier, and an ultraviolet absorber may be added to the self-repairing coating composition for forming the coated body of the present invention. The blending amount of these additives can be appropriately set within a range not impairing the effects of the present invention. However, it is preferable that the coating film formed on the coated body of the present invention does not contain inorganic fine particles having a particle diameter of 1nm to 300nm, except for the colorant.

Examples

The present invention will be described in detail below with reference to examples. Further, the present invention is not limited to the embodiments shown below.

In the preparation of the self-healing coating composition, the following various materials were used.

[ component (A) ]

(A1) "Duranor G3450J" (manufactured by Asahi chemical Co., Ltd., resin component 100%, hydroxyl value 140mgKOH/G)

(A2) "Desmophen (registered trademark) C1100" (manufactured by Covestro corporation, resin component 100%, hydroxyl value 110mgKOH/g)

[ component (B) ]

(B1) "Acridic A859B" (acrylic polyol, available from DIC corporation, resin component 70 wt%, hydroxyl value of resin 143mgKOH/g)

(B2) "Acridic WFU-580" (acrylic polyol, manufactured by DIC corporation, resin component 62 wt%, hydroxyl value of resin 87mgKOH/g)

(B3) "Dianal JR-6642" (acrylic polyol, Mitsubishi chemical Co., Ltd., resin component 57 wt%, resin hydroxyl value 144mgKOH/g)

Ingredient (G)

The component (G) is a hydroxyl group-containing resin component other than the components (A) and (B).

(G1) "Acridic WXU-880" (acrylic polyol, available from DIC Co., Ltd., resin component 50 wt%, resin hydroxyl value of 20mgKOH/g)

Ingredient (C)

(C1) "Desmodur N3300" (manufactured by Sumitomo Covestrouthane Co., isocyanurate-modified hexamethylene diisocyanate, NCO concentration 21.8% by weight, non-volatile component 100% by weight)

(C2) "Duranate MHG-80B" (manufactured by Asahi Kasei K.K., isocyanurate-modified hexamethylene diisocyanate, NCO concentration 15.1% by weight, non-volatile component 100% by weight)

(C3) "Desmodur N3580" (made by Sumitomo covestiurethane Co., isocyanurate-modified hexamethylene diisocyanate in butyl acetate having an NCO concentration of 15.4% by weight and a nonvolatile content of 80% by weight)

Solvent(s)

(D1) Acetic acid butyl ester

(D2) Ethyl acetate

Pigment dispersion liquid

(E1) Carbon black dispersion (manufactured by NIKKO BICS co., Ltd, active ingredient 23 wt%)

Other additives

(F1) "BYK 306" (silicon-based surface conditioner, manufactured by BYK-Chemie K.K.)

(F2) "TINUVIN 400" (ultraviolet absorber, Hydroxyphenyltriazine (HPT) -based ultraviolet absorber, manufactured by BASF corporation)

(F3) "TINUVIN 123" (light stabilizer, hindered amine light stabilizer, manufactured by BASF corporation)

< coating formation >

The prepared coating material was applied to a polycarbonate resin plate using an air sprayer at a coating amount such that the dry film thickness was 25 μm or more and 30 μm or less, left at room temperature for 10 minutes, and then dried at 80 ℃ for 30 minutes, thereby obtaining coated bodies of examples 1 to 4 and comparative examples 1 to 3. The glass transition temperature, the inter-crosslinking molecular weight, the Young's modulus and the elongation of the coating film were measured and evaluated by the following methods. In addition, the oil and grease contamination resistance and the scratch resistance were measured and evaluated by the following methods. The results are shown in Table 1.

(1) Glass transition temperature (Tg (m)) of coating film

The coating films of the coated bodies of examples 1 to 4 and comparative examples 1 to 3 were peeled off from the polypropylene resin plate, and then cut into samples having a length of 50mm and a width of 8mm, thereby preparing samples for measurement. In the dynamic viscoelasticity measurement, a dynamic glass transition temperature measured as a temperature representing a maximum value of tan δ (loss elastic modulus/storage elastic modulus) was defined as a glass transition temperature of a sample for measurement at a measurement length of 24mm, a frequency of 1Hz, and a heating rate of 5 ℃/min using a dynamic viscoelasticity measuring apparatus RSA G2 (manufactured by TA Instruments).

(2) Crosslink density

The molecular weight of the resin between crosslinks is called the inter-crosslink molecular weight, and the larger the crosslink density, the smaller the value, expressed by the reciprocal of the crosslink density.

The inter-crosslinking molecular weight of the cured coating film of the present invention is a theoretical calculation value obtained by using the following theoretical formula for rubber viscoelasticity, as the minimum value of the storage elastic modulus obtained in the measurement of the glass transition temperature of the cured coating film.

Equation 1: n is E'/3RT,

here, the number of the first and second electrodes,

n: crosslink Density (mol/cc)

1/n: cross-linking intermolecular weight (cc/mol)

R: gas constant (8.314J/K/mol)

T: absolute temperature (K) at storage elastic modulus E

E': minimum value of storage elastic modulus (Pa)

(3) Young's modulus

The Young's modulus was measured by the following method. First, the coating films of the coated bodies of examples 1 to 4 and comparative examples 1 to 3 were peeled from the polypropylene plate and cut into strips having a length of 50mm and a width of 10mm, thereby obtaining samples for measurement. Next, using a precision universal tester Autograph AG-1100 kN (manufactured by Shimadzu co., ltd.) in a load cell: 100N, measurement temperature: 23 ℃ and stretching speed: 20mm/min and chuck spacing: the test specimen was stretched in the longitudinal direction until it broke at 30mm, and a stress-strain curve was obtained. Then, the young's modulus was calculated from a tangent line to the rising portion of the obtained stress-strain curve.

(4) Elongation percentage

The coating films of the coated bodies of examples 1 to 4 and comparative examples 1 to 3 were peeled off from the polypropylene plate and cut into a length of 50 mm. times.10 mm in width, thereby obtaining a sample for measurement.

An automatic chart AG-1100 kN was prepared at 23 ℃ using a precision universal tester manufactured by Shimadzu corporation, in a dynamometer: 100N, measurement temperature: 23 ℃, stretching speed: the measurement sample was subjected to a tensile test at a speed of 20mm/min, and the elongation of the coating film was calculated by the following calculation formula. Here, the length of the measurement sample in the tensile test was set to 30 mm.

{ (length of sample for measurement at break in tensile test-length of sample for measurement before test)/(length of sample for measurement before test) } × 100 ═ elongation (%) of coating film.

(5) Resistance to oil contamination

According to JIS K5600-5-4: 1999(ISO/DIS 15184: 1996), the pencil hardness of the coating film before chemical treatment was judged by a pencil for scratch hardness test (Uni MITSUBISHI, Mitsubishi Pencil Co., Ltd.). Then, a sunscreen cream (trade name: Ultra sheet Dry Touch Sunblock SPF45, manufactured by Leucong (Neutrogena) Co., Ltd.; ultraviolet absorber: salicylate derivative (10 mass%) and benzophenone derivative (5 mass%) was applied to the surface of the coating film of the coated body at a ratio of 0.5g/100cm2, and then the coated body was left to stand at a temperature of 55. + -. 2 ℃ for 5 hours in a dryer without forced convection, and subjected to chemical treatment. Then, the sunscreen agent was removed by washing with water, and finally, the pencil hardness of the coating film after the chemical treatment was determined by the same method.

O: the coating film does not swell

X: swelling of the coating film was observed

(6) Scratch resistance

Using a reciprocating transverse tester (manufactured by KNT inc.), a test piece according to JIS L0803: 2011 the white cloth attached to the standard fastness test is subjected to 5000 reciprocations with a load of 900g applied to the surface of the coating film of the coated body. After 5000 reciprocations, the appearance of the coating film after standing for 6 days was evaluated by visual observation.

O: no significant scratches were observed

X: obvious scratches were observed

The above results are shown in Table 1.

TABLE 1

As shown in examples 1 to 4, in the coated body of the present invention, the glass transition temperature of the coating film and the young's modulus of the coating film were adjusted to be within the prescribed ranges, so that both the scratch resistance and the chemical resistance were satisfied. On the other hand, in the coated bodies of comparative examples 1 and 2, chemical resistance became poor in correspondence with the fact that the glass transition temperature of the coating film was 30 ℃ or less, and in the coated body of comparative example 3, scratch resistance became poor in correspondence with the fact that the young's modulus of the coating film exceeded 1000N/mm 2. From the above, in the present invention in which the glass transition temperature and young's modulus of the coating film are adjusted, it is understood that the scratch resistance and chemical resistance of the coating film are in a trade-off relationship with each other.

Claims

1. A coated body comprising a plastic substrate and a coating film formed on a surface of the plastic substrate, wherein the coating film satisfies the following conditions (1) and (2):

(1) the glass transition temperature of the coating is 30 ℃ to 60 ℃;

(2) the Young's modulus of the coating film is 50N/mm²Above 1000N/mm²Wherein the elongation of the coating film is 80% to 150%,

the coating film is formed of a self-repairing coating material containing a main agent and the following curing agent (C), the main agent containing at least the following (A) and (B) as hydroxyl group-containing components;

(A) a polycarbonate diol having a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less and a glass transition temperature of-100 ℃ or more and 0 ℃ or less; and

(B) a hydroxyl value of 80mgKOH/g or more and 200mgKOH/g or less, a glass transition temperature of 50 ℃ or more and 120 ℃ or less, and at least one selected from the group consisting of acrylic polyol, polyester polyol and polyether polyol;

(C) an isocyanate curing agent;

wherein the ratio (B)/(A) of the hydroxyl value of the component (A) to the hydroxyl value of the component (B) is 0.5 to 1.5;

the amount of the component (B) is 40 to 150 parts by mass based on 100 parts by mass of the component (A).

2. The coated body according to claim 1,

wherein the coating film has two or more glass transition temperatures, and the average value of the glass transition temperatures is 30 ℃ or more and 60 ℃ or less.

3. The coated body according to claim 1,

wherein the coating film has a molecular weight between crosslinks of 700 to 1200.

4. The coated body according to claim 1,

wherein the weight average molecular weight of the component (A) is 500 to 2000, and the weight average molecular weight of the component (B) is 5000 to 100000.

5. The coated body according to claim 1,

wherein the total amount of the component (A) and the component (B) is 70% by mass or more based on the total amount of the hydroxyl group-containing components.

6. The coated body according to claim 1,

wherein the coating film formed on the surface of the plastic substrate does not contain inorganic fine particles having a particle diameter of 1 to 300nm, except for the coloring material.