Moisture-curing resin sheet, vehicle component, vehicle, and method for manufacturing vehicle and vehicle component

Abstract

The present invention provides a moisture-curing resin sheet having a transfer layer and a resin layer, wherein the resin layer comprises a (meth)acrylic resin (A) having isocyanate groups.

Description

Technical Field

[0001] This invention relates to moisture-curing resin sheets, vehicle parts, vehicles, and methods for manufacturing vehicles and vehicle parts. Background Technology

[0002] Previously, coating was used to impart design, durability, weather resistance, and scratch resistance to various products such as furniture, steel sheets, and vehicle bodies. Coating was typically performed through air spraying or electrostatic spraying. However, considering the losses during the coating process, CO2 emissions from factories, and large-scale equipment investment, resin film-based decorative technologies are currently being explored as alternatives to spray-based coatings.

[0003] Decorative techniques refer to the application of resin films (decorative films) printed with text and patterns using white, black, or colored inks onto substrates for decoration, thereby exhibiting high functionality and design capabilities. For example, thermosetting resin sheets containing thermosetting resin and a curing agent are known as decorative films. After being adhered to the substrate, the thermosetting resin sheet is heated to cure, thus achieving a high degree of adhesion to the substrate.

[0004] However, thermosetting resin sheets require heating after lamination, which may prevent their use depending on the type of substrate being adhered to. Therefore, moisture-curing resin sheets are being researched as decorative films.

[0005] Generally speaking, moisture-curing polyurethane resins, such as those disclosed in Patent Document 1, are widely used as moisture-curing resins. Furthermore, it is also known, for example, as shown in Patent Document 2, to introduce an acrylic backbone into the polyurethane prepolymer used in moisture-curing polyurethane resins.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 7363124

[0009] Patent Document 2: Japanese Patent No. 6584382 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, for decorative resin sheets (resin layers), to facilitate adhesion to the substrate, they are sometimes laminated onto the transfer layer. In this case, if the resin sheet is peeled off from the transfer layer before curing and cured in an exposed state, foreign matter can adhere and cause damage. Furthermore, if the transfer layer is peeled off in an uncured state, stickiness and streaks may occur, or the surface may become rough due to resin adhering to the transfer layer. Therefore, to maintain a smooth surface for the resin layer, it is preferable to cure it while the transfer layer is still attached.

[0012] However, according to the inventors' research, if polyurethane resin, which is a conventional moisture-curing resin, is used in the decorative resin sheet and cured while a transfer layer is attached, gases such as carbon dioxide generated during curing cannot escape and will leave air bubbles in the cured coating, resulting in a rough surface.

[0013] In addition, the resin composition disclosed in Patent Document 2 is a coating-type hot melt resin composition, which is difficult to apply to decorative resin sheets.

[0014] Therefore, the objective of this invention is to provide a moisture-curing resin sheet that can form a coating layer with a good surface condition by suppressing the generation of bubbles during curing.

[0015] Problem-solving methods

[0016] The inventors conducted in-depth research and found that by including (meth)acrylic resins with isocyanate groups in the resin layer of a moisture-curing resin sheet having a transfer layer and a moisture-curing resin layer, the above-mentioned problems can be solved, thereby completing the following invention. That is, the present invention provides the following [1]~

[12] .

[0017] [1] A moisture-curing resin sheet having a transfer layer and a resin layer, wherein the resin layer comprises a (meth)acrylic resin (A) having an isocyanate group.

[0018] [2] According to the moisture-curing resin sheet described in [1] above, the weight-average molecular weight of the (meth)acrylic resin (A) is 10,000 or more and 500,000 or less.

[0019] [3] The moisture-curing resin sheet according to [1] or [2] above further contains a compound (B) having two or more isocyanate groups other than the (meth)acrylic resin (A).

[0020] [4] According to the moisture-curing resin sheet described in [3] above, the molecular weight of the compound (B) is less than 1000.

[0021] [5] In any one of the above [1] to [4], the content of the (meth)acrylic resin (A) in the resin layer is 30% by mass or more.

[0022] [6] The moisture-curing resin sheet according to any one of [1] to [5] above, wherein the (meth)acrylic resin (A) has isocyanate groups on its side chain.

[0023] [7] The moisture-curing resin sheet according to any one of [1] to [6] above, wherein the isocyanate group content of the (meth)acrylic resin (A) is 0.5% by mass or more and 15% by mass or less.

[0024] [8] The moisture-curing resin sheet according to any one of [1] to [7] above, wherein the resin layer comprises pigment.

[0025] [9] A vehicle component having a coating layer formed from a moisture-curing resin sheet as described in any one of [1] to [8] above.

[0026]

[10] A vehicle having a coating layer formed from any one of the moisture-curing resin sheets described in any one of [1] to [8].

[0027]

[11] A method for manufacturing a vehicle, comprising a step of coating using a moisture-curing resin sheet as described in any one of [1] to [8] above.

[0028]

[12] A method for manufacturing a vehicle component, comprising a step of coating using a moisture-curing resin sheet as described in any one of [1] to [8] above.

[0029] Invention Effects

[0030] According to the present invention, a moisture-curing resin sheet can be provided to form a coating layer with a good surface condition by suppressing the generation of bubbles during curing. Attached Figure Description

[0031] Figure 1 This is a cross-sectional schematic diagram showing one embodiment of a moisture-curing resin sheet.

[0032] Figure 2 This is a cross-sectional schematic diagram showing one embodiment of a moisture-curing resin sheet. Detailed Implementation

[0033] Moisture-curing resin sheets

[0034] Hereinafter, the moisture-curing resin sheet of the present invention will be described with reference to embodiments. Figure 1 , 2As shown, the moisture-curing resin sheet 10 includes a resin layer 11 and a transfer layer 12, with the transfer layer 12 laminated onto one surface of the resin layer 11. The moisture-curing resin sheet 10 can be as follows: Figure 1 It can be composed of a resin layer 11 and a transfer layer 12 as shown, or it can be as follows: Figure 2 As shown, a release layer 13 is further provided, which can be laminated to the side of the resin layer 11 opposite to the side where the transfer layer 12 is provided. Hereinafter, the constituent elements of the moisture-curing resin sheet will be described in detail.

[0035] [Resin Layer]

[0036] The resin layer of the present invention comprises a (meth)acrylic resin (A) having isocyanate groups. By comprising a (meth)acrylic resin (A) having isocyanate groups, the resin layer can suppress the generation of bubbles during curing, even when cured in a transfer layer laminated state, thus preventing surface roughness during curing and forming a cured layer with a good surface condition. The principle is not yet certain, but it is speculated that by giving the (meth)acrylic resin (A) isocyanate groups, gas generation can be suppressed even during moisture curing, or gas can be generated in a way that does not form bubbles, thereby preventing surface roughness during curing. It should be noted that it is speculated that the (meth)acrylic resin, due to the polarity of its ester groups, has the ability to adsorb a certain amount of water and carbon dioxide, and slowly releases them after adsorption, thus suppressing gas generation during curing.

[0037] ((Meth)acrylic resin (A))

[0038] (Meth)acrylic resin (A) is a moisture-curing resin that possesses moisture-curing properties due to the presence of isocyanate groups. (Meth)acrylic resin (A) preferably has isocyanate groups on its side chains. Furthermore, (meth)acrylic resin (A) may have two or more isocyanate groups per molecule.

[0039] (Meth)acrylic resin (A) is not particularly limited as long as it contains isocyanate groups; however, (meth)acrylates with isocyanate groups are preferred as raw materials. Therefore, (meth)acrylic resin (A) is preferably a polymer containing structural units derived from (meth)acrylates with isocyanate groups. Because (meth)acrylic resin (A) contains structural units derived from (meth)acrylates with isocyanate groups, and the isocyanate groups are positioned close to the main chain, the molecular arrangement after curing becomes more regular, resulting in good curability. Therefore, while achieving a good surface condition, it is also easier to improve the hardness of the cured resin layer.

[0040] The (meth)acrylate used as a raw material has an isocyanate group, wherein the (meth)acrylate-derived portion of the compound forms the main chain in the polymer, and the isocyanate group is configured as a side chain in the polymer. In a (meth)acrylate resin (A) molecule, multiple isocyanate groups may be present in the side chain. Furthermore, the (meth)acrylate resin (A) may or may not have an isocyanate group at the end.

[0041] It should be noted that in this specification, (meth)acrylate is used as a term to refer to one or both of acrylate and methacrylate, and so are other similar terms.

[0042] (Meth)acrylate resin (A) is a polymer formed by polymerizing a monomer (a) containing (meth)acrylate. It is acceptable as long as the main chain has structural units derived from (meth)acrylate. Preferably, it is a polymer formed by polymerizing a monomer (a) containing (meth)acrylate with isocyanate groups. More preferably, it is a polymer formed by polymerizing a monomer (a) containing both (meth)acrylate with isocyanate groups and alkyl (meth)acrylate. By using alkyl (meth)acrylate, adhesiveness can be imparted to the resin layer before curing. Furthermore, monomer (a) may further contain monomers other than (meth)acrylate with isocyanate groups and alkyl (meth)acrylate (other monomers).

[0043] Examples of (meth)acrylates having an isocyanate group include ethyl (meth)acrylate, butyl (meth)acrylate, alkyl (meth)acrylate, alkyl (meth)acrylate, 2-(2-isocyanate ethoxy)ethyl (meth)acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate, among which alkyl (meth)acrylate is preferred. It should be noted that the number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is not particularly limited, for example, it is about 1 to 10, preferably 2 to 4.

[0044] Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, myristyl methacrylate, isomyristyl methacrylate, and stearyl methacrylate, where the alkyl group has approximately 1 to 18 carbon atoms. From the perspective of imparting adhesion to the resin layer before curing, alkyl methacrylates are preferably those with 1 to 12 carbon atoms in the alkyl group. Furthermore, from the perspective of improving adhesion before curing, alkyl methacrylates containing alkyl groups with 3 to 10 carbon atoms are more preferred.

[0045] In addition to isocyanate groups and alkyl methacrylates, other monomers that can be listed include alicyclic methacrylates such as cyclohexyl methacrylate and isobornyl methacrylate; aromatic methacrylates such as benzyl methacrylate and phenoxydiethylene glycol methacrylate; styrene monomers such as styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-ethoxystyrene, p-chlorostyrene, m-chlorostyrene, and o-chlorostyrene; and vinyl monomers such as vinyl acetate and vinyl propionate.

[0046] The amount of (meth)acrylate having isocyanate groups in the monomer (a) constituting the (meth)acrylate resin (A) is preferably 2 mol% or more and 40 mol% or less, more preferably 5 mol% or more and 30 mol% or less, and even more preferably 8 mol% or more and 25 mol% or less.

[0047] By setting the amount of (meth)acrylate with isocyanate groups within the above range, even when cured in a state where it is transferred and laminated onto a resin layer, it is easy to suppress the generation of bubbles during curing. In addition, it is easy to improve the adhesion before curing, the adhesion after curing, and the hardness after curing in a balanced manner.

[0048] Furthermore, the amount of alkyl (meth)acrylate used in monomer (a) is preferably 50 mol% or more and 98 mol% or less, more preferably 65 mol% or more and 95 mol% or less, and even more preferably 70 mol% or more and 92 mol% or less. By setting the amount of alkyl (meth)acrylate used to the lower limit or above, it is easy to improve flexibility and obtain good adhesion before curing. In addition, by setting it to the upper limit or below, it is easy to contain a certain amount of isocyanate groups, and the adhesion and hardness after curing are also easily improved.

[0049] The alkyl acrylate in monomer (a) is preferably an alkyl acrylate containing 3 to 10 carbon atoms, which is preferred in order to improve flexibility and obtain good adhesion before curing. The amount of the alkyl acrylate containing 3 to 10 carbon atoms in monomer (a) is preferably 30 mol% or more and 98 mol% or less, more preferably 35 mol% or more and 95 mol% or less, and even more preferably 40 mol% or more and 90 mol% or less.

[0050] The weight-average molecular weight of the (meth)acrylic resin (A) is preferably 10,000 or more and 500,000 or less. By keeping the weight-average molecular weight of the (meth)acrylic resin (A) within the above range, the coatability, curability, adhesion, elongation, etc., of the resin layer can be easily and evenly improved. The weight-average molecular weight of the (meth)acrylic resin (A) is more preferably 20,000 or more and 300,000 or less, and even more preferably 40,000 or more and 100,000 or less. It should be noted that in this specification, the weight-average molecular weight is determined by gel permeation chromatography (GPC) and is used as a conversion value for standard polystyrene.

[0051] The isocyanate group content in the (meth)acrylic resin (A) is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 2% by mass or more and 8% by mass or less. If it is 0.5% by mass or more, the crosslinking reaches a certain value, the hardness becomes appropriate, and the degradation of solvent resistance, etc., can be prevented. In addition, by setting it to 15% by mass or less, it will not become too hard and will not easily crack. In addition, it can also prevent the storage stability from decreasing.

[0052] The isocyanate group content mentioned here refers to the proportion of the mass of NCO molecules (molecular weight 42) in the total mass of (meth)acrylic resin (A), determined, for example, by potentiometric titration according to JIS K 1603-1. That is, the sample is mixed with di-n-butylamine and reacted, and the residual di-n-butylamine is titrated with hydrochloric acid standard solution using potentiometric titration, thereby determining the amount of NCO.

[0053] The content of (meth)acrylic resin (A) in the resin layer is, for example, 20% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. By ensuring that the content of (meth)acrylic resin (A) is at least a certain amount, not only can the surface condition of the resin layer be improved, but the adhesion before curing, the hardness of the resin layer after curing, and the adhesion to the adhered object can also be easily improved. The content of (meth)acrylic resin (A) in the resin layer is only required to be 100% by mass or less. Considering the presence of other components such as compound (B) in a certain amount or more, it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0054] (Compound (B))

[0055] The moisture-curing resin sheet preferably further comprises a compound (B) having isocyanate groups (a polyisocyanate compound). By containing compound (B), the moisture-curing resin sheet can improve the hardness of the cured resin layer, thus resulting in good mechanical strength and damage resistance of the cured resin layer. Compound (B) may have two or more isocyanate groups. Furthermore, compound (B) is a compound other than the aforementioned (meth)acrylic resin (A), and preferably a compound that does not contain a polyacrylic acid backbone.

[0056] As compound (B), examples include hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate, isophorone diisocyanate (IPDI), phenyldimethyl diisocyanate, hydrogenated phenyldimethyl diisocyanate (H6XDI), hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, bis(isocyanate methyl)cyclohexane, dicyclohexylmethane diisocyanate, and other aliphatic diisocyanate compounds, as well as aromatic diisocyanate compounds such as 4,4-diphenylmethane diisocyanate, toluene diisocyanate, and naphthalene-1,5-diisocyanate, and other polyisocyanates.

[0057] Compound (B) can be a modified product obtained by polymerizing the above-mentioned polyisocyanate, such as polymerized MDI, or a polyol modified polyisocyanate (adduct) such as a trimethylolpropane adduct of polyisocyanate, a biuret polyisocyanate, a ureocarbamate polyisocyanate, an isocyanurate polyisocyanate, and their condensates. Preferred examples include HDI adducts, HDI biuret, HDI ureocarbamate, HDI isocyanurate, H6XDI isocyanurate, IPDI isocyanurate, and IPDI adducts.

[0058] As compound (B), it is preferable to select a compound that is soft and has high adhesion in the uncured state. From this point of view, aliphatic polyisocyanates or their modified forms are preferred, among which adducts, biuret bodies, urea carbamate bodies, and isocyanurates are more preferred, and adducts, biuret bodies, urea carbamate bodies, and isocyanurates of HDI and IPDI are even more preferred.

[0059] Compound (B) can be used alone or in combination of two or more.

[0060] The molecular weight of compound (B) is not particularly limited, but is preferably 1000 or less. By reducing the molecular weight of compound (B), the adhesion of the resin layer before curing and its adhesion to the adhered object after curing can be improved. The molecular weight of compound (B) is preferably 800 or less, more preferably 700 or less. The molecular weight of compound (B) is not particularly limited, for example, 160 or more is acceptable, preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more.

[0061] It should be noted that the molecular weight of compound (B) is calculated from its structural formula. Furthermore, when two or more compounds (B) are used together, the molecular weight refers to the weight-average molecular weight.

[0062] When using compound (B), if the total amount of (meth)acrylic resin (A) and compound (B) is considered to be 100 parts by mass, the content of compound (B) in the resin layer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more. By ensuring that the content of compound (B) is at least a certain amount, the hardness of the cured resin layer can be easily improved. Furthermore, the content of compound (B) can be, for example, 80 parts by mass or less, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By ensuring that the content of compound (B) is at least a certain value, the surface condition of the resin layer can be improved, and the adhesion before curing and the adhesion after curing of the resin layer can be easily improved.

[0063] (Moisture-curing accelerating catalyst)

[0064] The resin layer may contain a moisture-curing accelerator to promote the moisture-curing reaction. By using a moisture-curing accelerator, the moisture-curing properties of the resin layer are improved, and the hardness and adhesion of the cured resin layer are also easily increased. In addition, even in low external temperatures such as winter, it can be properly cured by being placed in the air.

[0065] As a catalyst for promoting moisture curing, amine compounds and metal catalysts can be specifically listed. Examples of amine compounds include di(methylmorpholino)diethyl ether, 4-morpholinopropylmorpholine, 2,2'-dimorpholinodiethyl ether and other compounds with a morpholine skeleton; bis(2-dimethylaminoethyl) ether, 1,2-bis(dimethylamino)ethane and other amine compounds containing two dimethylamino groups; triethylamine; 1,4-diazabicyclo[2.2.2]octane; 2,6,7-trimethyl-1,4-diazabicyclo[2.2.2]octane, etc.

[0066] Examples of metal catalysts include tin compounds such as di-n-butyltin dilaurate, di-n-butyltin diacetate, and tin octoate; zinc compounds such as zinc octoate and zinc naphthenate; and other metal compounds such as zirconium tetraacetylacetonate, copper naphthenate, and cobalt naphthenate.

[0067] The content of the moisture curing promoting catalyst in the resin layer is preferably 0.001 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total mass of (meth)acrylic resin (A) and compound (B), more preferably 0.01 parts by mass or more and 3.5 parts by mass or less, and even more preferably 0.02 parts by mass or more and 2 parts by mass or less.

[0068] (Surface conditioner)

[0069] The resin layer may contain surface modifiers. Surface modifiers adjust surface tension and improve wettability. Examples of surface modifiers include silicone-acrylic copolymers, silicones, polyacrylates, and fluorinated compounds. By including surface modifiers in the resin layer, the wettability of the resin layer can be improved, thereby increasing the peel strength relative to the adhered substrate. In addition, the smoothness and slip properties of the surface can be adjusted, improving scratch resistance.

[0070] The content of surface conditioner in the resin layer is preferably 0.01 parts by mass or more and 3 parts by mass or less, more preferably 0.05 parts by mass or more and 2 parts by mass or less, and even more preferably 0.1 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of the total amount of (meth)acrylic resin (A) and compound (B).

[0071] (Coloring agent)

[0072] The resin layer can be used for, for example, to protect or enhance the appearance of the adhered object. Therefore, the resin layer can contain a colorant to form a colored layer. The colorant can be pigment, dye, or a glossy material. Pigments are preferred.

[0073] Pigments used as colorants can include, but are not limited to, inorganic pigments such as titanium dioxide, iron oxide, and other metal oxide pigments; carbon black, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silicon dioxide, and alumina white; azo pigments; quinacridone pigments; diketopyrrolopyrrole pigments; perylene pigments; violet ketone pigments; benzimidazolone pigments; reduction pigments; isoindoline pigments; isoindoline ketone pigments; metal chelate azo pigments; phthalocyanine pigments; indanone pigments; dioxane pigments; and indigo pigments.

[0074] As dyes, well-known dyes can be used, such as azo dyes, anthraquinone dyes, indigo dyes, and zirconia dyes.

[0075] Glossy materials are compounds that impart a glossy finish to resin layers, meaning they possess the property of exhibiting a glossy appearance when viewed from multiple directions. There are no particular limitations on what constitutes a glossy material; examples include compounds with a titanium dioxide layer deposited on the surface of natural mica, synthetic mica, alumina flakes, glass flakes, etc.

[0076] There is no particular limitation on the content of colorant in the resin layer, but it is preferably 0.05% by mass or more and about 15% by mass or less, preferably 0.1% by mass or more and 12% by mass or less, and more preferably 0.3% by mass or more and 8% by mass or less.

[0077] Alternatively, the resin layer can be a transparent layer that is substantially free of colorants. The transparent layer is transparent, as long as it has enough transparency to allow the color of the colored layer to be seen from the outside through the transparent layer; for example, it should have a transmittance of 80% or more for light with a wavelength of 450 nm. The transparent layer is preferably a resin layer free of colorants, but it may contain a small amount of colorant as long as it does not impair its function. There are no particular limitations on the content of colorant in the transparent layer; for example, it is 0 to 2% by mass, preferably 0 to 0.5% by mass, and more preferably 0 to 0.1% by mass.

[0078] In addition, the resin layer can be used to impart functions beyond protecting or beautifying the adhered object; for example, it can be used as a heat-insulating coating. In this case, the coating layer formed by the resin layer simply functions as a heat-insulating coating, and the resin layer can be made to contain a heat-insulating agent to form a heat-insulating layer. Furthermore, by creating surface irregularities on the resin layer, surface properties such as matte or embossed finishes can be imparted. Moreover, functions such as rust prevention, mildew prevention, heat insulation, and antistatic properties can also be achieved by incorporating components that meet the desired objectives (such as rust inhibitors, mildew inhibitors, and antistatic agents) into the resin layer.

[0079] The resin layer may contain components other than those described above, such as additives other than those listed above. Examples of additives include inorganic fillers other than plasticizers, colorants, and heat-insulating agents, dispersants, anti-aging agents, antioxidants, and ultraviolet absorbers. Furthermore, the resin layer may contain resin components other than those described in (A) and (B) above, without impairing the effects of the present invention.

[0080] The resin layer can consist of a single layer or a multilayer structure with two or more layers, but a single-layer structure is preferred. Making the resin layer a single-layer structure simplifies its manufacture. Furthermore, by creating a multilayer structure, various functions can be imparted to the coating layer formed by the resin layer. It should be noted that when the resin layer has a multilayer structure, it is sufficient that the resin layer as a whole contains the components described above in the aforementioned amounts, and each layer is preferably a resin layer as described above. In the case of a multilayer structure, the formulations of each layer can be the same or different, but they are generally different from each other.

[0081] When the resin layer has a multilayer structure, it may include at least one of a coloring layer containing a colorant and a transparent layer that does not substantially contain a colorant, but it is preferable to have both a coloring layer and a transparent layer. When both a coloring layer and a transparent layer are present, the transparent layer and the coloring layer can be sequentially arranged starting from the transfer layer side. Due to this layer structure, when the moisture-curing resin sheet is adhered to the substrate, the coloring layer and the transparent layer are sequentially arranged starting from the substrate side.

[0082] As described above, the resin layer, by having a coloring layer, allows the adhered object to be colored using a coating layer formed from the resin layer. Furthermore, since a transparent layer is provided in addition to the resin layer, the coloring layer can be protected or given a glossy finish.

[0083] It should be noted that for the coloring layer in a multilayer structure, the content of the colorant only needs to be within the above-mentioned range, and the same applies to the transparent layer, where the content of the colorant only needs to be within the above-mentioned range.

[0084] Of course, when the resin layer has a multi-layer structure, it is not limited to a two-layer structure of transparent layer and coloring layer. Various laminated structures are possible. For example, a structure with three or more layers can be formed by setting two or more coloring layers and one or more transparent layers, or the transparent layer can be omitted, consisting of two coloring layers. Additionally, two or more transparent layers can be set. Furthermore, a structure with three or more layers can be formed by setting a heat insulation layer or similar material between the transparent layer and the coloring layer.

[0085] There are no particular limitations on the thickness of the resin layer, for example, it is about 5 μm or more and 1000 μm or less, preferably 15 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. It should be noted that when the resin layer has a multilayer structure, the thickness of the resin layer refers to its total thickness.

[0086] Furthermore, when a coloring layer and a transparent layer are provided in the resin layer, there is no particular limitation on the thickness of the coloring layer, for example, it is 5 μm or more and 500 μm or less, preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 50 μm or less. Similarly, there is no particular limitation on the thickness of the transparent layer, for example, it is 5 μm or more and 500 μm or less, preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 50 μm or less.

[0087] (Transfer layer)

[0088] The transfer layer is a component that protects the resin layer from damage and the adhesion of foreign matter, and forms a support when the resin layer is adhered to the substrate. The transfer layer can be formed from a resin film. The resin used in the resin film is preferably a thermoplastic resin, but it can also be a resin other than a thermoplastic resin. Specifically, examples of resins used for resin films include cyclic polyolefin resins, polyethylene resins, polypropylene resins, ethylene-vinyl acetate copolymer resins, polybutylene terephthalate, polybutylene terephthalate, polyamide resins, acrylonitrile-butadiene-styrene resins, polycarbonate resins, acrylic resins, fluoropolymers, vinyl chloride resins, polymethylpentene resins, and tetrafluoroethylene resins.

[0089] The resin film constituting the transfer layer can be a single-layer film or a multilayer film consisting of two or more layers. Furthermore, the resin film constituting the transfer layer can contain only one type of resin or two or more types of resin used simultaneously. When using two or more types of resin simultaneously, different types of resin can be used in each layer to form a multilayer film. Alternatively, a single-layer film can be formed using a material formed by mixing two or more resins, or one or more layers of a multilayer film can be formed.

[0090] In addition, the resin film used in the transfer layer can be a stretched resin film or an unstretched resin film.

[0091] The transfer layer can be a transfer layer on which at least one surface has been treated with a release agent such as a silicone-based release agent or a fluorinated release agent. When the transfer layer is treated with a release agent, the surface treated with the release agent preferably forms the side of the resin layer. The transfer layer, by performing a release agent, can be easily peeled from the resin layer. However, the transfer layer may not require a release agent as long as it can be peeled from the resin layer.

[0092] There are no particular limitations on the thickness of the transfer layer, for example, it can be 10 μm or more and 1000 μm or less, preferably 30 μm or more and 700 μm or less, and more preferably 50 μm or more and 500 μm or less. If the thickness of the transfer layer is within the above range, the transfer layer can be endowed with a certain degree of strength and flexibility.

[0093] (release layer)

[0094] The release layer is a component that protects the resin layer from damage and foreign matter adhesion. The release layer is preferably formed of a resin film. The resin used for the resin film in the release layer is preferably a thermoplastic resin, but it can also be a resin other than a thermoplastic resin. Specific examples of the resin used for the resin film in the release layer are the same as those used in the transfer layer. The resin used for the release layer and the resin used for the transfer layer can be the same as each other or different.

[0095] The resin film forming the release layer can be a single-layer film or a multilayer film consisting of two or more layers. Furthermore, the resin film constituting the release layer can contain only one type of resin or two or more resins simultaneously. When using two or more resins simultaneously, different types of resins can be used in each layer to create a multilayer film. Alternatively, a single-layer film can be formed using a material formed by mixing two or more resins, or one or more layers of a multilayer film can be formed.

[0096] In addition, the resin film used in the release layer can be a stretched resin film or an unstretched resin film.

[0097] The release layer may have at least one surface treated with a release agent such as a silicone-based or fluorinated release agent. When the release layer is treated, the treated surface preferably forms the side of the resin layer. For the release layer, the treatment facilitates good peelability from the resin layer. However, for the release layer, as long as it can be peeled from the resin layer, a release treatment may not be necessary.

[0098] There is no particular limitation on the thickness of the release layer, for example, it is 10 μm or more and 1000 μm or less, preferably 30 μm or more and 700 μm or less, and more preferably 50 μm or more and 500 μm or less.

[0099] (Manufacturing method of moisture-curing resin sheet)

[0100] There are no particular limitations on the manufacturing method of moisture-curing resin sheets. Known methods can be used, such as preparing a moisture-curing resin composition, coating the prepared moisture-curing resin composition onto a transfer layer, and drying it as needed to form a resin layer. The moisture-curing resin composition only needs to contain (meth)acrylic resin (A), and may optionally contain compound (B), surface conditioner, moisture-curing accelerator, colorant, or other components. It should be noted that the details and content of each component in the moisture-curing resin composition are as described in the resin layer section above; however, the content reference in the case of the resin layer is the resin layer itself. Simply replace the resin layer with the amount of solids in the moisture-curing resin composition excluding volatile components as the content reference.

[0101] Furthermore, when the moisture-curing resin sheet has a release layer, a resin layer can be formed by coating the moisture-curing resin composition onto the release layer, drying it as needed, and then further bonding a transfer layer onto the resulting resin layer formed on the release layer to obtain the moisture-curing resin sheet. It should be noted that when coating the curing resin composition onto the transfer layer or the release layer, the curing resin composition can be appropriately diluted using a solvent or the like. Examples of solvents include ethyl acetate, butyl acetate, and toluene. For example, a solvent used in the preparation of (meth)acrylic resin (A) can also be used.

[0102] Furthermore, when the resin layer is multilayered, it can be formed by sequentially forming each layer and laminating them. For example, when a transparent layer and a coloring layer are provided, it is preferable to sequentially laminate the transparent layer and the coloring layer onto the transfer layer. Additionally, when the moisture-curing resin sheet has a release layer, the moisture-curing resin sheet can be obtained by bonding one or more resin layers formed on the release layer to one or more resin layers formed on the transfer layer. In the case of multiple layers, as described above, it is also preferable to form each layer from a moisture-curing resin composition containing the aforementioned components in the aforementioned amounts. The formulations of each layer can be the same or different, but they are generally different from each other.

[0103] It should be noted that, in order to prevent moisture absorption and curing, the resin layer is preferably formed in a low-humidity environment.

[0104] [Painting Method]

[0105] The moisture-curing resin sheet of the present invention can be used as a coating sheet. It can be applied to an object and then the resin layer is cured to form a coating layer formed by the cured resin layer on the surface of the object.

[0106] The following describes in detail one embodiment of a coating method for forming a coating layer on a substrate using the moisture-curing resin sheet of the present invention. The coating method of one embodiment of the present invention includes the following first step and second step.

[0107] First step: Applying the moisture-curing resin sheet to the object to be bonded.

[0108] The second step: Curing the moisture-curing resin sheet.

[0109] (First process)

[0110] The first step is to attach the moisture-curing resin sheet to the object to be bonded.

[0111] Before applying a moisture-curing resin sheet to a substrate, a release layer can be laminated onto the side of the resin layer opposite to the side where the transfer layer is located. With the release layer laminated, the moisture-curing resin sheet can be peeled off from the resin layer before being applied to the substrate, exposing the resin layer and allowing it to adhere to the substrate. There are no particular limitations on the method of peeling off the release layer; it can be done using a peeling device or manually. Alternatively, the release layer can be omitted from the moisture-curing resin sheet design.

[0112] In this process, the moisture-curing resin sheet, with its exposed resin layer, is bonded to the substrate by bringing the resin layer into contact with it. There are no particular restrictions on the bonding method of the moisture-curing resin sheet; it can be applied manually or using a lamination device. Since the resin layer is formed from a moisture-curing resin composition and is uncured at the time of application, it easily ensures a certain degree of flexibility. Therefore, the resin layer adheres appropriately to the substrate and can be temporarily fixed to it with moderate adhesive force.

[0113] Alternatively, moisture-curing resin sheets can also be bonded using a method known as water bonding. Water bonding is performed as follows: First, water is applied to the substrate, and then the moisture-curing resin sheet is bonded to the water-coated surface. Next, a scraper or similar tool is used to squeeze out the water between the moisture-curing resin sheet and the substrate. This process removes air bubbles and other particles present between the moisture-curing resin sheet and the substrate, allowing the moisture-curing resin sheet to be completely bonded to the substrate. The water applied to the substrate can be pure water, or additives such as surfactants or organic solvents can be added appropriately.

[0114] Moisture-curing resin sheets can be pre-formed using methods such as vacuum forming, compression molding, and air-forming. They can also be shaped to correspond to the shape of the substrate, and then the shaped moisture-curing resin sheet is adhered to the substrate. When the moisture-curing resin sheet has a release layer, pre-forming can be performed before or after the release layer is peeled from the resin layer. Pre-forming allows for easy adhesion of the moisture-curing resin sheet even to substrates with complex shapes. Pre-forming is preferably performed using vacuum forming, as described above. For pre-forming, the coated sheet can be pressed onto a fixture or mold using vacuum forming, while the fixture or mold elongates the moisture-curing resin sheet and shapes it to correspond to the surface shape of the substrate.

[0115] Here, vacuum forming is preferably TOM forming. TOM stands for "Three Dimension Overlay Method," which allows for the shaping of complex forms.

[0116] (Second process)

[0117] The second step, performed after the first step, is to cure the resin layer of the moisture-curing resin sheet. In this step, the resin layer is cured to a degree suitable for use as a coating layer. There are no particular restrictions on the curing of the resin layer as long as it is cured with moisture; it can typically be placed in air or a humidified environment (e.g., at room temperature or near room temperature, preferably 5-30°C) at room temperature or near room temperature (e.g., 0-45°C, preferably 5-30°C). There are no particular restrictions on the time spent in air or a humidified environment; for example, it can be more than 1 hour and less than 2 weeks, preferably more than 1 day and less than 1 week.

[0118] The moisture-curing resin sheet of the present invention can be cured simply by being placed in air, thus enabling industrial curing of the resin layer without the introduction of large-scale equipment. Furthermore, the resin layer can be properly cured even when the adhered objects are large and difficult to heat, or when the adhered objects have low heat resistance.

[0119] In the coating method of the present invention, a further step of peeling the transfer layer from the resin layer may be included. The transfer layer can be peeled off using a peeling device or manually. The peeling of the transfer layer can be performed before, after, or during the second step described above. Preferably, the peeling of the transfer layer is performed after the resin layer has cured to a certain extent. Therefore, it is preferable to peel the transfer layer after leaving it in the air for a certain period of time (e.g., more than 1 hour, preferably more than 1 day). If the resin layer has cured to a certain extent, uncured or poorly cured resin layers can be prevented from being exposed to the outside, thus preventing dust or damage from adhering to the resin layer before curing. Furthermore, by peeling the transfer layer off the resin layer that has cured to a certain extent, damage to the resin layer during peeling can also be prevented.

[0120] Moisture-curing resin sheets can be adhered to various substrates to form a coating layer. There are no particular limitations on the substrates to which moisture-curing resin sheets can be adhered, including vehicle parts such as automotive interior materials and other transportation equipment interior materials, automotive exterior materials and other transportation equipment exterior materials, exterior materials for heavy machinery, ships, and aircraft, exterior wall or roofing materials for residences and buildings, bridges, steel frames, factory equipment, wind turbine blades, electrical products, and daily necessities.

[0121] The preferred application is to vehicles and vehicle components, with vehicle exterior materials, such as those used for transportation equipment other than automobiles, being the preferred adhesive. The vehicle exterior materials are preferably the exterior of the vehicle body, but can also include the hood, roof, door panels, bumpers, fuel filler panels, trunk lid, rear door, etc. The moisture-curing resin sheet, when applied to the vehicle exterior materials, can be adhered to exterior materials already installed on the vehicle body, or to exterior materials that were previously installed on the vehicle body.

[0122] In addition, there are no particular restrictions on the material of the object to be adhered to. It can be any of the following: resin materials, inorganic materials such as ceramics, and metal materials such as steel. Among them, metal materials such as steel are preferred.

[0123] Alternatively, a base layer can be appropriately formed on the surface of the substrate to which the moisture-curing resin sheet is adhered.

[0124] Furthermore, this invention also provides a method for manufacturing a vehicle and a method for manufacturing vehicle components. The method for manufacturing a vehicle or vehicle component of this invention includes a coating step using the moisture-curing resin sheet of this invention. In the coating step, the vehicle or vehicle component can be coated using the methods described in the above coating method.

[0125] Example

[0126] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples in any way.

[0127] The measurement and evaluation methods in this embodiment are as follows.

[0128] (1) Evaluation of adhesion before curing

[0129] Moisture-curing resin sheets were cut into 1-inch (2.54 cm) widths. After peeling off the PET film that forms the release layer, the sheets were adhered to a coating plate (SPCC-SD polyurethane coating test sheet manufactured by Standard Test Piece) using a scraper. The adhesive strength (N / inch) of the adhered film was determined by a 180° peel test at 25°C and a tensile speed of 30 mm / s.

[0130] (2) Bubble generation

[0131] After cutting the moisture-curing resin film into 5cm squares, the PET film constituting the release layer was peeled off and then adhered to the same coating plate as (1) by water bonding. The bonded test piece was placed in an environment of 25°C and 70%RH for 5 days with the PET film constituting the transfer layer bonded on it to allow the resin layer to moisture cure. After moisture curing, it was visually confirmed whether the PET film had peeled off due to gas generation. When bubbles and peeling occurred on the entire surface of the transfer layer due to gas generation, it was rated as "C", when bubbles appeared locally, it was rated as "B", and when there was no peeling or bubbles, it was rated as "A".

[0132] (3) Pencil hardness

[0133] Using the same method as (2) above, the PET film constituting the transfer layer is peeled off after being bonded to the steel plate and the resin layer is cured by moisture. The hardness of the pencil is measured on the exposed surface of the resin layer in accordance with JIS K 5600-5-4.

[0134] (4) Evaluation of cross-cutting test

[0135] Using the same method as described in (2) above, the PET film constituting the transfer layer is adhered to the steel plate and allowed to cure with moisture. The resin layer is then peeled off. A cross-cut test conforming to JIS K 5600-5-6 is performed on the resin layer, and the evaluation is conducted according to the following evaluation criteria.

[0136] <Evaluation Criteria>

[0137] A: The test results are classified as 0~2

[0138] B: The test results are classified as 3 or higher.

[0139] (Manufacturing Example 1)

[0140] In a 1L glass reaction vessel equipped with a stirrer, thermometer, and condenser, 20g of methyl methacrylate (hereinafter referred to as "MMA"), 77g of butyl acrylate (hereinafter referred to as "BA"), 31g of ethyl 2-isocyanate methacrylate (trade name "Karens MOI", manufactured by Resonac Co., Ltd., hereinafter referred to as "MOI"), 2.0g of 2,2'-azobis-2,4-dimethylpentanonitrile (manufactured by Wako Pure Chemical Industries Co., Ltd., trade name "V-65", hereinafter referred to as "V-65"), and 200g of ethyl acetate (hereinafter referred to as "EA") were added and allowed to dissolve uniformly at room temperature. While stirring the contents of the flask, the internal temperature was raised to 60°C under a nitrogen atmosphere, and solution polymerization was carried out for 6 hours to obtain a solution (40% by mass) of acrylic resin (A-1) with isocyanate groups on the side chains. The weight-average molecular weight of the obtained acrylic resin (A-1) was 80,000. Furthermore, in the monomers constituting the acrylic resin (A-1), MMA is 20 mol%, BA is 60 mol%, and MOI is 20 mol%. Additionally, the isocyanate group content (NCO content) of the obtained acrylic resin (A-1) is 7.0% by mass.

[0141] (Manufacturing Example 2)

[0142] In a 1L glass reaction vessel equipped with a stirrer, thermometer, and condenser, 44g of MMA, 56g of BA, 18.5g of MOI, 2.0g of V-65, and 200g of EA were added and allowed to dissolve uniformly at room temperature. While stirring the contents of the flask, the internal temperature was raised to 60°C under a nitrogen atmosphere and solution polymerization was carried out for 6 hours to obtain a solution of acrylic resin (A-2) with isocyanate groups on the side chains (38% by mass of solids). The weight-average molecular weight of the obtained polymer was 70,000. Furthermore, in the monomers constituting acrylic resin (A-2), MMA accounted for 44 mol%, BA for 44 mol%, and MOI for 12 mol%. The isocyanate group content of the obtained acrylic resin (A-2) was 4.6% by mass.

[0143] (Manufacturing Example 3)

[0144] The amount of initiator V-65 in Manufacturing Example 2 was changed to 3.0 g. Otherwise, a solution of acrylic resin (A-3) (38% by mass solids) was obtained using the same method as in Manufacturing Example 2. The weight-average molecular weight of the obtained polymer was 30,000. Furthermore, in the monomers constituting acrylic resin (A-3), MMA was 44 mol%, BA was 44 mol%, MOI was 12 mol%, and the isocyanate group content of acrylic resin (A-3) was 4.6% by mass.

[0145] (Manufacturing Example 4)

[0146] The amount of initiator V-65 in Manufacturing Example 2 was changed to 0.5 g. Otherwise, a solution of acrylic resin (A-4) (38% by mass solids) was obtained using the same method as in Manufacturing Example 2. The weight-average molecular weight of the obtained polymer was 250,000. Furthermore, in the monomers constituting acrylic resin (A-4), MMA was 44 mol%, BA was 44 mol%, MOI was 12 mol%, and the isocyanate group content of acrylic resin (A-4) was 4.6% by mass.

[0147] (Manufacturing Example 5)

[0148] In Manufacturing Example 2, methyl methacrylate (hereinafter referred to as "MMA") was changed to 10g, butyl acrylate (hereinafter referred to as "BA") to 64g, and ethyl 2-isocyanate methacrylate (trade name "Karrens MOI", manufactured by Resonac Co., Ltd., hereinafter referred to as "MOI") to 64g. Otherwise, an acrylic resin (A-5) solution (38% by mass solids) was obtained using the same method as in Manufacturing Example 2. The weight-average molecular weight of the obtained polymer was 50,000. Furthermore, in the monomers constituting the acrylic resin (A-5), MMA was 10 mol%, BA was 50 mol%, MOI was 40 mol%, and the isocyanate group content of the acrylic resin (A-5) was 11.9% by mass.

[0149] (Manufacturing Example 6)

[0150] In Manufacturing Example 2, methyl methacrylate (hereinafter referred to as "MMA") was changed to 37 g, butyl acrylate (hereinafter referred to as "BA") to 77 g, and ethyl 2-isocyanate methacrylate (trade name "Karrens MOI", manufactured by Resonac Co., Ltd., hereinafter referred to as "MOI") to 4.7 g. Otherwise, an acrylic resin (A-6) solution (38% by mass solids) was obtained using the same method as in Manufacturing Example 2. The weight-average molecular weight of the obtained polymer was 80,000. Furthermore, in the monomers constituting the acrylic resin (A-6), MMA was 37 mol%, BA was 60 mol%, MOI was 3 mol%, and the isocyanate group content of the acrylic resin (A-6) was 0.9% by mass.

[0151] The components used in the resin layer, other than (meth)acrylic resins, are as described below.

[0152] Polyurethane prepolymer: Trade name "Takenet M-605N", manufactured by Mitsui Chemicals Co., Ltd.

[0153] Polyisocyanate (1): Trade name "Desmojule N3200A", manufactured by Covestro, HDI biuret, molecular weight 479

[0154] Polyisocyanate (2): Trade name "Takenet D-140N", manufactured by Mitsui Chemicals Co., Ltd., isophorone diisocyanate adduct, molecular weight 801

[0155] Surface conditioner: Trade name "BYK-378", manufactured by BYK Corporation.

[0156] Catalysts: Moisture-curing accelerator, 2,2'-dimorpholinodiethyl ether (manufactured by Tokyo Chemical Co., Ltd., reagent)

[0157] Pigment: "NSP-UP 841B" manufactured by Nichihiro BIXS Co., Ltd., effective pigment concentration = 9% by mass, solids concentration (NV) = 24% by mass.

[0158] (Example 1)

[0159] A solution of a moisture-curing resin composition was prepared by adding 0.2 parts by mass of a surface conditioner to a solution of (meth)acrylic resin (A-1) obtained from Manufacturing Example 1 (100 parts by mass of (meth)acrylic resin (A-1) on a solids basis). The moisture-curing resin composition solution was applied by a doctor blade to a 50 μm thick PET film (manufactured by Nakamoto Packs Co., Ltd., trade name "NS-50B") as a release layer in a drying workbench (dew point -50°C) with a thickness of 50 μm after drying. Then, it was heated on a heating plate at 100°C for 5 minutes to dry the solvent and form a resin layer. A PET film (manufactured by Nakamoto Packs Co., Ltd., trade name "NS-50C") as a transfer layer was laminated onto the obtained resin layer and stored in a moisture-proof bag.

[0160] (Examples 2-9, Comparative Example 1)

[0161] Prepare a moisture-curing resin composition by combining the components as shown in Table 1, otherwise proceed in the same manner as in Example 1.

[0162]

[0163] *The content of each component in Table 1 is based on the amount of solids.

[0164] *The effective component amount of the pigment is obtained by multiplying the value in Table 1 by 9 / 24.

[0165] In Examples 1-9, by using (meth)acrylic resins with isocyanate groups as moisture-curing resins, even when moisture curing is performed with a transfer layer laminated, bubble generation can be suppressed, and a coating layer with a good surface condition can be formed.

[0166] In contrast, in Comparative Example 1, which uses polyurethane resin as a moisture-curing resin, if the transfer layer is laminated and then moisture-cured, it is impossible to suppress the generation of bubbles and obtain a coating layer with a good surface condition.

Claims

1. A moisture-curing resin sheet comprising a transfer layer and a resin layer, wherein the resin layer comprises a (meth)acrylic resin (A) having isocyanate groups.

2. The moisture-curing resin sheet according to claim 1, wherein the (meth)acrylic resin (A) has a weight-average molecular weight of 10,000 or more and 500,000 or less.

3. The moisture-curing resin sheet according to claim 1 or 2, further comprising a compound (B) having two or more isocyanate groups other than the (meth)acrylic resin (A).

4. The moisture-curing resin sheet according to claim 3, wherein the molecular weight of compound (B) is less than 1000.

5. The moisture-curing resin sheet according to any one of claims 1 to 4, wherein the content of the (meth)acrylic resin (A) in the resin layer is 30% by mass or more.

6. The moisture-curing resin sheet according to any one of claims 1 to 5, wherein the (meth)acrylic resin (A) has isocyanate groups on its side chain.

7. The moisture-curing resin sheet according to any one of claims 1 to 6, wherein the isocyanate group content in the (meth)acrylic resin (A) is 0.5% by mass or more and 15% by mass or less.

8. The moisture-curing resin sheet according to any one of claims 1 to 7, wherein the resin layer comprises pigment.

9. A vehicle component having a coating layer formed from a moisture-curing resin sheet according to any one of claims 1 to 8.

10. A vehicle having a coating layer formed from a moisture-curing resin sheet according to any one of claims 1 to 8.

11. A method for manufacturing a vehicle, comprising a step of coating using a moisture-curing resin sheet according to any one of claims 1 to 8.

12. A method for manufacturing a vehicle component, comprising a step of coating using a moisture-curing resin sheet according to any one of claims 1 to 8.

Images