Coating protective coating material and coating composition

Abstract

To provide a coating film protective coat material which is formed from a liquid coating composition, exhibits good peelability when removed from a coating film, and has a good trace prevention property.SOLUTION: A coating film protective coat material formed from a liquid coating composition is provided. The coating composition contains a polymer (A) as a base polymer which is a polymer of a monomer component containing an acrylic monomer. The polymer (A) has an SP value of 9.8 (cal / cm3)1 / 2 or more and has a glass transition temperature of 0°C or lower as calculated on the basis of the composition of the monomer component constituting the polymer (A).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coating material for protecting a coating film and a coating composition for forming the coating material for protecting a coating film.

Background Art

[0002] For the purpose of preventing damage to a coating film during transfer, storage, curing, application, etc. of an article having a coating film (for example, a painted automobile or its parts, or a metal plate such as a painted steel plate or its molded product, etc.), a technique of attaching a protective sheet to the coating film for protection is known. A coating film protection sheet used for such a purpose generally has the form of a single-sided adhesive sheet with a substrate having an adhesive layer (also referred to as a pressure-sensitive adhesive. The same applies hereinafter) on one side of a sheet-like substrate (support substrate), and is configured to achieve the protection purpose by being attached to an adherend (protection target object) through the adhesive. After the coating film protection sheet has completed its role of protection, it is then removed (re-peeled) from the adherend. As a technical document regarding the coating film protection sheet, Patent Document 1 can be cited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, for non-planar objects to be protected (especially those with complex three-dimensional shapes, such as the body panels of automobiles), it is difficult to improve the efficiency of properly applying the protective coating sheet to the object. If the protective coating sheet is not properly applied to the object to be protected, for example, if it is applied with wrinkles, wind may blow into these wrinkles during storage or transport of the object after application, causing the protective coating sheet to peel off and failing to fulfill its intended protective purpose.

[0005] On the other hand, it has also been proposed to directly apply a liquid composition for forming a protective film onto the coating of the object to be protected, and then dry the liquid composition on the coating to form a protective film. Patent Document 2 is an example of a document relating to this type of technology. However, unlike the coating protective sheets described above, protective films formed from liquid compositions in this way do not have a substrate, and therefore tend to lack peelability when removed from the coating after the protective role has been fulfilled. Furthermore, protective films formed from liquid compositions (coating protective coating materials) are required to have the ability to not leave any trace of the protective film on the coating after it has been removed, similar to conventional coating protective sheets, i.e., to prevent leaving traces. It has been particularly difficult to improve peelability while preventing traces.

[0006] Therefore, the present invention aims to provide a coating protective coating material formed from a liquid coating composition that exhibits good peelability when removed from the coating and good resistance to leaving marks. Another related objective is to provide a coating composition suitable for forming the above-mentioned coating protective coating material and a method for forming the above-mentioned coating protective coating material. [Means for solving the problem]

[0007] This specification provides a coating protective coating material (hereinafter sometimes abbreviated as "coating material") formed from a liquid coating composition. The coating composition contains polymer (A), which is a polymer of monomer components including an acrylic monomer, as a base polymer. Polymer (A) has an SP value of 9.8 (cal / cm³).3 ) 1 / 2 That concludes the explanation. Furthermore, the above polymer (A) has a glass transition temperature (hereinafter also referred to as "calculated Tg") of 0°C or lower, calculated based on the composition of the above monomer components. Such a protective coating material can achieve a good balance between good peelability from the coating and good resistance to leaving marks.

[0008] In some embodiments of the technologies disclosed herein (including coating protective coating materials, coating compositions, coating protective methods, etc.; the same applies hereinafter), the acid value of polymer (A) is 15 mg KOH / g or less. By limiting the acid value of polymer (A) to a predetermined level or less, it becomes easier to suppress the peel strength when peeling the coating material formed on the coating film from the coating film. This is preferable from the viewpoint of improving peelability and peeling workability.

[0009] The protective coating material disclosed herein preferably has a storage modulus of elasticity at 70°C (hereinafter sometimes referred to as "G'(70)") of 0.40 MPa or higher. A coating material having such a G'(70) may have good peelability from the coating film.

[0010] In some embodiments, the monomer component preferably contains a nitrogen atom-containing monomer. That is, the polymer (A) is preferably a polymer of the monomer component containing a nitrogen atom-containing monomer. With a monomer component of this composition, it is easy to obtain a polymer (A) that has both a calculated Tg below a predetermined value and an SP value above a predetermined value.

[0011] In some embodiments, the polymer (A) has a Tg of -20°C or higher, calculated based on the composition of the monomer components. It is preferable that the calculated Tg of polymer (A) is not too low, from the viewpoint of improving the ease of peeling from the coating film.

[0012] In some embodiments, the monomer components constituting the polymer (A) may have a composition comprising an alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms at its ester terminus and a carboxyl group-containing monomer. A polymer (A) composed of monomer components of such a composition makes it easier to obtain a coating material that balances trace resistance, peelability, and peelability well, as well as a coating composition suitable for forming such a coating material.

[0013] Furthermore, this specification provides a coating composition used to form any of the coating protective coating materials disclosed herein. The coating protective coating materials disclosed herein can preferably be formed using the above-mentioned coating composition, for example, by applying the coating composition onto a coating and drying it.

[0014] In some embodiments of the technology disclosed herein, the coating composition is preferably an aqueous emulsion composition in which the polymer (A) is dispersed in an aqueous solvent. Such aqueous emulsion-type coating compositions are preferred from the viewpoint of environmental hygiene and are suitable, for example, for suppressing the amount of organic solvent used and emitted.

[0015] This specification provides a method for protecting a coating film, comprising: preparing one of the coating compositions disclosed herein; applying the coating composition onto a coating film on an object to be protected having a coating film; and drying the coating composition to form a coating protective coating material that temporarily protects the coating film. According to this method, the coating film can be adequately protected by the coating material. Furthermore, the coating material can achieve a good balance between good peelability from the coating film and good resistance to leaving marks.

[0016] In some preferred embodiments, the coating composition is applied by a slot die. By drying the slot die-coated coating composition, a protective coating material can be efficiently formed on the coating film.

[0017] Furthermore, combinations of the elements described herein may also be included within the scope of the invention for which patent protection is sought in this application. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view showing an example of an object protected by the coating protective material according to the present invention. [Figure 2] This is a block diagram showing one embodiment of the coating protection method according to the present invention. [Modes for carrying out the invention]

[0019] Preferred embodiments of the present invention are described below. Matters other than those specifically mentioned herein that are necessary for carrying out the present invention can be understood by those skilled in the art based on the teachings on carrying out the invention described herein and the common technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed herein and the common technical knowledge in the art. In the following drawings, components and parts that perform the same function may be denoted by the same reference numeral and described accordingly, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic representations for the purpose of clearly illustrating the present invention and do not necessarily accurately represent the size or scale of the actual product provided.

[0020] In this specification, "acrylic monomer" is a comprehensive term referring to monomers having at least one (meth)acryloyl group in one molecule (hereinafter also referred to as "(meth)acryloyl group-containing monomers") and (meth)acrylonitrile. In this specification, "(meth)acryloyl" is a comprehensive term referring to acryloyl and methacryloyl. Similarly, "(meth)acrylate" is a comprehensive term referring to acrylate and methacrylate, "(meth)acrylic" is a comprehensive term referring to acrylic and methacrylic, and "(meth)acrylonitrile" is a comprehensive term referring to acrylonitrile and methacrylonitrile.

[0021] <Polymer (A)> The protective coating material disclosed herein is formed from a coating composition containing polymer (A) as a base polymer. Here, "base polymer" refers to a component that accounts for more than 50% by weight (typically 70% by weight or more, for example 90% by weight or more, and may also be 95% by weight or more, or 100% by weight) of the polymer contained in the coating composition. The same meaning applies to the base polymer in protective coating material. Polymer (A) is a polymer of monomer components including acrylic monomers. Therefore, polymer (A) is a polymer containing monomer units derived from acrylic monomers.

[0022] The above polymer (A) has a value of 9.8 or higher (unit [(cal / cm²) 3 ) 1 / 2]. The same applies hereafter.) has an SP value of 9.8 or higher. A polymer (A) having an SP value of 9.8 or higher may have an SP value that is far from (typically, farther from) the SP value of the coating film to be protected. The coating film may be, for example, a urethane coating film formed by the reaction of a polyol (e.g., acrylic polyol) and a polyisocyanate, or a coating film formed from an acid epoxy crosslinked acrylic paint. By moving the SP value of polymer (A) away from the SP value of the coating film, the interaction between the coating material containing polymer (A) and the coating film tends to decrease. This is advantageous in terms of preventing the occurrence of peeling defects due to excessively high peel strength of the coating material from the coating film, suppressing increased burden on peeling work, and suppressing deformation (marking) of the coating film due to mass transfer between the coating film and the coating material. In some embodiments, the SP value of polymer (A) is preferably 9.9 or higher, more preferably 10.0 or higher, may be 10.5 or higher, may be 10.8 or higher, may be 11.2 or higher, and may be 11.5 or higher. There is no particular upper limit to the SP value of polymer (A). From the viewpoint of facilitating compatibility with a calculated Tg below a predetermined level and facilitating the formation of a coating material with a good balance of properties, in some embodiments, the SP value of polymer (A) is generally appropriate to be 14.0 or less, but may also be 13.5 or less, 13.0 or less, less than 12.5, 12.0 or less, less than 12.0, and 11.5 or less.

[0023] Herein, in this specification, the SP value refers to the value of the solubility parameter calculated from the basic structure of a compound using the method proposed by Fedors. The SP value of polymer (A) can be adjusted by selecting the composition of the monomer components that constitute polymer (A), specifically by selecting the type and quantity ratio of monomers contained in the monomer components.

[0024] In some embodiments, the SP value of polymer (A) is appropriately 0.2 or higher than the SP value of the coating film to be protected, preferably 0.5 or higher, more preferably 0.7 or higher, and even more preferably 1.0 or higher. By combining polymer (A) and the coating film to be protected having such a difference in SP values, good peelability and good resistance to marks of the coating material containing polymer (A) can be suitably achieved.

[0025] The polymer (A) described above has a glass transition temperature (calculated Tg) of 0°C or lower, calculated based on the composition of the monomer components constituting the polymer (A). A coating material containing polymer (A) designed to have a calculated Tg of 0°C or lower as a base polymer can have good resistance to leaving marks on the coating film. By including polymer (A) as a base polymer that is designed to have a calculated Tg of 0°C or lower while satisfying the above SP value, a coating material with good peelability when removed from the coating film and good resistance to leaving marks can be suitably realized. A calculated Tg of polymer (A) of 0°C or lower is also preferable from the viewpoint of making it easier to realize a coating material with a moderately large elongation at break, as described later. The lower limit of the calculated Tg of polymer (A) is not particularly limited and may be, for example, -50°C or higher. In some embodiments, from the viewpoint of ease of peeling (for example, suppression of peeling defects due to chipping or tearing of the coating material) when peeling the coating material from the coating film in a temperature range near room temperature (for example, around 15-30°C), the calculated Tg of polymer (A) is appropriately -40°C or higher, advantageously -35°C or higher, preferably -20°C or higher, may also be -15°C or higher, or -13°C or higher. On the other hand, from the viewpoint of making it easier to prevent marks, the calculated Tg of polymer (A) may be, for example, -1.0°C or lower, may be -5.0°C or lower, may be -8.0°C or lower, or may be -10.0°C or lower. Lowering the calculated Tg of polymer (A) is also preferable from the viewpoint of ease of peeling when peeling the coating material from the coating film in low-temperature environments such as outdoors in winter, and is also advantageous from the viewpoint of suppressing the occurrence of cracks in the coating material due to differences in the coefficient of linear expansion between the coating material and the protected object when the protected object to which the coating material is applied is exposed to temperature changes. The calculated Tg of polymer (A) can be adjusted by selecting the composition of the monomer components that make up polymer (A), specifically by selecting the type and quantity ratio of monomers contained in the monomer components.

[0026] Herein, in this specification, the calculated Tg of a polymer refers to the Tg determined by Fox's formula based on the composition of the monomer components used in the synthesis of the polymer. Fox's formula is a relationship between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below. 1 / Tg = Σ(Wi / Tgi) In Fox's equation above, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the monomer i homopolymer (unit: K).

[0027] The glass transition temperatures of homopolymers used in calculating Tg shall be those specified in publicly available documents. For example, for the monomers listed below, the following values ​​shall be used as the glass transition temperatures of the homopolymers of those monomers. n-butyl acrylate -55℃ Acrylonitrile 97℃ Vinyl acetate 32℃ Methyl methacrylate 105℃ Acrylic acid 106℃ For the glass transition temperatures of monomer homopolymers other than those exemplified above, the values ​​listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. If the Tg of a homopolymer is not listed in the publicly available documents, the value obtained by the measurement method described in Japanese Patent Publication No. 2007-51271 shall be used. Specifically, 100 parts by weight of monomer, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as the polymerization solvent are added to a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, and the mixture is stirred for 1 hour while circulating nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Next, the mixture is cooled to room temperature to obtain a homopolymer solution with a non-volatile content of 33% by weight. Next, this homopolymer solution is cast onto a release liner and dried to produce a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. This test sample is punched out into a 7.9 mm diameter disc shape, sandwiched between parallel plates, and measured using a viscoelasticity tester (manufactured by T.A. Instruments Japan, model name "ARES") in shear mode while applying a shear strain of 1 Hz at a frequency, in the temperature range of -70 to 150°C, with a heating rate of 5°C / min. The peak top temperature of tanδ is defined as the Tg of the homopolymer.

[0028] The polymer (A) in the technology disclosed herein is a polymer of a monomer component comprising one or more acrylic monomers. The proportion of the acrylic monomer in the monomer component may be, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, may be 25 mol% or more, may be 35 mol% or more, may be 45 mol% or more, may be more than 50 mol%, or may be more than 70 mol%. In some preferred embodiments, the proportion of the acrylic monomer in the monomer component may be 85 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol%. Also, in some embodiments, the proportion of the acrylic monomer in the monomer component may be 50 mol% or less, may be 40 mol% or less, or may be 30 mol% or less.

[0029] In some embodiments, the monomer components constituting polymer (A) include at least a (meth)acryloyl group-containing monomer as the acrylic monomer. The (meth)acryloyl group-containing monomer can be used alone or in combination of two or more. The proportion of the (meth)acryloyl group-containing monomer among the monomer components may be, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, more preferably 20 mol% or more, may be 30 mol% or more, may be 40 mol% or more, may be 45 mol% or more, may be 50 mol% or more, may be 55 mol% or more, or may be 60 mol% or more. The entire monomer component (i.e., 100 mol%) may be a (meth)acryloyl group-containing monomer. From the viewpoint of facilitating compatibility with a calculated Tg below a predetermined level and facilitating the formation of a coating material with a good balance of properties, in some embodiments, the proportion of (meth)acryloyl group-containing monomers in the above monomer components is preferably 95 mol% or less, more preferably 90 mol% or less, and may also be 85 mol% or less, 80 mol% or less, 75 mol% or less, or 70 mol% or less. The technology disclosed herein can also be implemented in embodiments in which the proportion of (meth)acryloyl group-containing monomers in the monomer components is 65 mol% or less, 55 mol% or less, 45 mol% or less, or 35 mol% or less.

[0030] The monomer components constituting the polymer (A) described above preferably include at least an alkyl (meth)acrylate as the (meth)acryloyl group-containing monomer. Depending on the type and amount used, the alkyl (meth)acrylate can be useful for adjusting the storage modulus, adjusting the tensile properties, adjusting the SP value described later, etc. One type of alkyl (meth)acrylate can be used alone or in combination of two or more types.

[0031] As the alkyl (meth)acrylate, for example, a compound represented by the following formula (1) can be suitably used. CH2=C(R 1 )COOR2 (1) Here, R in the above formula (1) 1 is a hydrogen atom or a methyl group. R in the above formula (1) 2 is a linear alkyl group having 1 to 20 carbon atoms. Hereinafter, such a carbon atom number range may be represented as "C 1-20 ". The linear alkyl group may be linear or may have a branch.

[0032] R 2 is an alkyl (meth) acrylate in which the alkyl group is C 1-20 Specific examples of the alkyl (meth) acrylate (C 1-20 alkyl (meth) acrylate) are not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. can be mentioned.

[0033] Among these, it is preferable to use at least C 4-20 alkyl (meth) acrylate (preferably C 4-14 alkyl (meth) acrylate) because it can contribute to the decrease in the calculated Tg of the polymer (A). Therefore, at least C 4-9It is more preferable to use alkyl acrylates. For example, it is preferable that the monomer component contains one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA), and more preferably at least BA.

[0034] Among the monomer components that make up polymer (A), C 1-20 The proportion of alkyl (meth)acrylate may be, for example, 5 mol% or more, preferably 10 mol% or more, preferably 15 mol% or more, may be 25 mol% or more, may be 35 mol% or more, may be 45 mol% or more, may be 55 mol% or more, and may be 60 mol% or more. Furthermore, from the viewpoint of making it easier to obtain polymer (A) that satisfies the above-mentioned predetermined SP value and predetermined calculated Tg, C among the monomer components 1-20 The proportion of alkyl (meth)acrylate is appropriately 95 mol% or less, preferably 90 mol% or less, and may also be 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less. The technology disclosed herein involves C among the monomer components. 1-20 The method can also be implemented in which the proportion of alkyl (meth)acrylate is 60 mol% or less, 50 mol% or less, 40 mol% or less, or 30 mol% or less.

[0035] The monomer component that makes up polymer (A) is C 4-9 In an embodiment comprising alkyl acrylate, among the monomer components, C 4-9 The proportion of alkyl acrylate may be, for example, 5 mol% or more, preferably 10 mol% or more, and preferably 15 mol% or more from the viewpoint of making it easier to obtain a lower calculated Tg. It may also be 25 mol% or more, 35 mol% or more, 40 mol% or more, or 45 mol% or more. On the other hand, from the viewpoint of making it easier to obtain polymer (A) having an SP value of a predetermined level or higher, C among the monomer components 4-9The proportion of alkyl acrylate is appropriately 80 mol% or less, preferably 70 mol% or less, and may also be 65 mol% or less, 60 mol% or less, or 55 mol% or less. The technology disclosed herein involves C among the monomer components. 4-9 The method can also be implemented in which the proportion of alkyl acrylate is 50 mol% or less, 40 mol% or less, 30 mol% or less, 25 mol% or less, or 20 mol% or less.

[0036] The monomer components constituting polymer (A) may include a combination of alkyl (meth)acrylate and monomers other than alkyl (meth)acrylate. Some examples of monomers other than alkyl (meth)acrylate include carboxyl group-containing monomers, hydroxyl group (OH group)-containing monomers, cyano group-containing monomers, amide group-containing monomers, amino group-containing monomers, monomers having a nitrogen atom-containing ring, acid anhydride group-containing monomers, epoxy group-containing monomers, keto group-containing monomers, alkoxysilyl group-containing monomers, and other functional group-containing monomers. The appropriate use of functional group-containing monomers can enhance the cohesive force of polymer (A). Functional group-containing monomers can also be useful for adjusting the storage modulus, adjusting the tensile properties, and adjusting the SP value, which will be discussed later.

[0037] Examples of carboxyl group-containing monomers include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Among these, AA and MAA are preferred. Examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and polypropylene glycol mono(meth)acrylate. Among these, hydroxyalkyl (meth)acrylates in which the alkyl group has 2 to 4 carbon atoms in a linear chain are particularly preferred as hydroxyl group-containing monomers.

[0038] Examples of cyano group-containing monomers include acrylonitrile, methacrylonitrile, and 2-cyanoethyl (meth)acrylate. Of these, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is particularly preferred. Examples of monomers containing an amide group include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and diacetone(meth)acrylamide. Examples of amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate. Examples of monomers having a nitrogen atom-containing ring include monomers in which a substituent with polymerizable functional groups is bonded to the nitrogen atom-containing ring, such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-(meth)acryloylmorpholine. Other examples include maleimide ring-containing monomers such as N-isopropylmaleimide and N-cyclohexylmaleimide. An example of an isocyanate group-containing monomer is 2-(meth)acryloyloxyethyl isocyanate.

[0039] Examples of monomers containing acid anhydride groups include maleic anhydride and itaconic anhydride. Examples of keto group-containing monomers include diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetacetate, and vinyl acetacetate. Examples of monomers having an epoxy group include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. Examples of monomers containing an alkoxysilyl group include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

[0040] The monomer components constituting polymer (A) may include other copolymer components other than the monomers mentioned above for purposes such as improving cohesiveness. Examples of other copolymer components include vinyl ester monomers such as vinyl acetate (VAc), vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyltoluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, and isobornyl (meth)acrylate; and aromatic rings such as aryl (meth)acrylate (e.g., phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (e.g., phenoxyethyl (meth)acrylate), and arylalkyl (meth)acrylate (e.g., benzyl (meth)acrylate). Examples include (meth)acrylate-containing monomers; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine atom-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy group-containing monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and ethyl carbitol (meth)acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; and polyfunctional monomers having two or more (e.g., three or more) polymerizable functional groups (e.g., (meth)acryloyl groups) in one molecule, such as 1,6-hexanediol di(meth)acrylate and trimethylolpropane tri(meth)acrylate.

[0041] In some embodiments, the monomer components constituting polymer (A) include nitrogen atom-containing monomers. Examples of nitrogen atom-containing monomers include at least one of the above-mentioned cyano group-containing monomers, amide group-containing monomers, amino group-containing monomers, and monomers having a nitrogen atom-containing ring. Nitrogen atom-containing monomers can be used individually or in combination of two or more. The above monomer components preferably include alkyl (meth)acrylate and nitrogen atom-containing monomers in combination, C 4-9It is more preferable to include a combination of alkyl acrylate and nitrogen atom-containing monomer. Nitrogen atom-containing monomers tend to exhibit relatively high SP values ​​(for example, higher SP values ​​than alkyl (meth)acrylates) due to the presence of a nitrogen-containing structural part. Appropriate use of nitrogen atom-containing monomers makes it easier to obtain polymer (A) having an SP value above a predetermined level. Furthermore, nitrogen atom-containing monomers generally tend to have a high Tg of homopolymers, and when nitrogen atom-containing monomers are used as monomer components constituting polymer (A), the calculated Tg of polymer (A) tends to increase. 4-9 By appropriately combining it with alkyl acrylate, a polymer (A) that achieves both a predetermined SP value and a predetermined Tg can be suitably realized.

[0042] In embodiments where the monomer component constituting polymer (A) includes nitrogen atom-containing monomers, the proportion of nitrogen atom-containing monomers among the monomer component can be set to obtain a desired effect. In some embodiments, the proportion of nitrogen atom-containing monomers among the monomer component may be, for example, 1 mol% or more, suitablely 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, may be 20 mol% or more, may be 25 mol% or more, may be 30 mol% or more, or may be 35 mol% or more. On the other hand, from the viewpoint of making it easier to keep the calculated Tg of polymer (A) below a predetermined level, the proportion of nitrogen atom-containing monomers among the monomer component may be 70 mol% or less, suitablely 65 mol% or less, suitablely 60 mol% or less, suitablely 55 mol% or less, suitablely 50 mol% or less, suitablely 45 mol% or less, or may be 40 mol% or less.

[0043] In some preferred embodiments, the monomer component constituting polymer (A) includes at least acrylonitrile as the nitrogen atom-containing monomer. Including acrylonitrile in the monomer component makes it easier to realize a coating material and a coating composition capable of forming such a coating material that achieves a good balance between good peelability and good anti-marking properties. The proportion of acrylonitrile among the nitrogen atom-containing monomers contained in the monomer component may be, for example, 25 mol% or more, 50 mol% or more, 70 mol% or more, 85 mol% or more, 95 mol% or more, or 100 mol%.

[0044] In embodiments in which the monomer component constituting polymer (A) contains acrylonitrile, the proportion of acrylonitrile in the monomer component may be, for example, 1 mol% or more, preferably 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, may be 20 mol% or more, may be 25 mol% or more, may be 30 mol% or more, or may be 35 mol% or more. On the other hand, from the viewpoint of making it easier to keep the calculated Tg of polymer (A) below a predetermined level, the proportion of acrylonitrile in the monomer component may be 70 mol% or less, preferably 65 mol% or less, may be 60 mol% or less, may be 55 mol% or less, may be 50 mol% or less, may be 45 mol% or less, or may be 40 mol% or less.

[0045] The acid value of polymer (A) is not particularly limited and may be, for example, 60 mgKOH / g or less. In some embodiments, from the viewpoint of suppressing peel strength from the coating film, it is advantageous for the acid value of polymer (A) to be 20.0 mgKOH / g or less, preferably 15.0 mgKOH / g or less, more preferably 12.0 mgKOH / g or less, and may also be 11.0 mgKOH / g or less, or 10.0 mgKOH / g or less. The techniques disclosed herein can also be implemented in embodiments where the acid value of polymer (A) is 8.0 mgKOH / g or less, 6.0 mgKOH / g or less, 3.0 mgKOH / g or less, or 1.0 mgKOH / g or less. The acid value of polymer (A) may be 0 mgKOH / g or higher. In some embodiments, from the viewpoint of improving the strength of the coating material (e.g., tensile strength), the acid value of polymer (A) may be, for example, 1.0 mgKOH / g or more, 2.0 mgKOH / g or more, 4.0 mgKOH / g or more, or 7.0 mgKOH / g or more. Increasing the strength of the coating material can be advantageous from the viewpoint of improving peelability (e.g., preventing tearing or chipping during peeling).

[0046] The acid value of polymer (A) is measured according to the potentiometric titration method specified in JIS K0070:1992. Specifically, the acid value can be measured by the method described in the examples below. For polymer (A) contained in a coating material, the coating material is placed in chloroform to obtain a mixture, which is allowed to stand for 12 hours. After that, the mixture is filtered, and a substance with a weight-average molecular weight of 10,000 or more (measured by GPC) is used as the sample. For polymer (A) contained in a coating composition, the coating composition is dried at 80°C for 3 minutes to form a film (coating material) with a thickness of approximately 100 μm, and the substance obtained in the same manner as the sample for measuring the acid value of polymer (A) contained in the coating material is used as the sample. For polymer (A) contained in an aqueous emulsion of polymer (A) described below, the substance obtained in the same manner as the sample for measuring the acid value of polymer (A) contained in the coating composition is used as the sample.

[0047] In some embodiments of the technology disclosed herein, the monomer component constituting the polymer (A) is a monomer (m) whose homopolymer Tg is 90°C or higher. T ) and monomers (m) whose homopolymer Tg is -30°C or lower. L ) includes the above monomer (m T ) may contain a nitrogen atom-containing monomer whose homopolymer Tg is 90°C or higher. An example of a nitrogen atom-containing monomer whose homopolymer Tg is 90°C or higher is acrylonitrile (homopolymer Tg: 97°C). Therefore, polymer (A) in this embodiment contains monomer (m L ) and monomers containing at least nitrogen atoms (e.g., acrylonitrile) (m T ) may be polymers of monomer components, and may further contain other monomers. The Tg of each monomer homopolymer shall be the same as the glass transition temperature of the homopolymer used to calculate the calculated Tg above, and the value described in the publicly available documents shall be used. If the Tg of the homopolymer is not described in the publicly available documents, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 shall be used.

[0048] Monomer (m L ) can moderately lower the calculated Tg of polymer (A), which may help to improve the trace-resistant properties of the coating material containing polymer (A). Lowering the calculated Tg of polymer (A) may also be advantageous from the viewpoint of improving the low-temperature properties of the coating material (e.g., suppression of crack formation at low temperatures, suppression of cracking or tearing when peeling from the coating film at low temperatures). monomer (m L As the monomer, one can be used if the Tg of the homopolymer is -30°C or lower, and can be selected from, for example, the various monomers mentioned above, but is not limited to these. L Monomers (m) can be used individually or in combination of two or more. LNon-limiting specific examples of monomers that can be used as ) include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), isooctyl acrylate, isononyl acrylate, isoamyl acrylate, 4-hydroxybutyl acrylate (4HBA), methoxyethyl acrylate, ethyl carbitol acrylate, ethoxy-diethylene glycol acrylate, and the like.

[0049] Monomer (m L The lower limit of the Tg of the homopolymer of each monomer used as is not particularly limited and may be, for example, -100°C or higher, -90°C or higher, or -80°C or higher. In some embodiments, monomers whose homopolymer Tg is in the range of -60°C or higher and -40°C or lower are used as monomers (m L ) can be preferably adopted as monomer (m L Of these, the proportion of monomers whose homopolymer Tg is in the range of -60°C to -40°C may be, for example, 50 mol% or more, 75 mol% or more, 85 mol% or more, 95 mol% or more, or 100 mol%.

[0050] Monomer (m T ) can be useful in improving the cohesive force and high-temperature properties of the coating material (e.g., suppression of the decrease in storage modulus in the high-temperature range, peelability at high temperatures, etc.). Monomer (m T Monomers (m) can be used individually or in combination of two or more. T The monomer may contain only one nitrogen atom-containing monomer, or it may contain a combination of two or more nitrogen atom-containing monomers, or it may contain a combination of one or more nitrogen atom-containing monomers and other monomers whose homopolymer Tg is 90°C or higher (i.e., monomers that do not fall under the category of nitrogen atom-containing monomers; hereinafter also referred to as "nitrogen atom-free monomers"). Monomer (m TAs the monomer, acrylonitrile may be used alone, or acrylonitrile may be used in combination with a nitrogen atom-free monomer whose homopolymer Tg is 90°C or higher, or acrylonitrile may be used in combination with a nitrogen atom-free monomer whose homopolymer Tg is 90°C or higher and a nitrogen atom-containing monomer whose homopolymer Tg is 90°C or higher (except acrylonitrile). The nitrogen atom-free monomer whose homopolymer Tg is 90°C or higher can be appropriately selected from the various monomers mentioned above, for example, but is not limited to these. The above nitrogen atom-free monomer can be used alone or in combination of two or more, together with a nitrogen atom-containing monomer whose homopolymer Tg is 90°C or higher (e.g., acrylonitrile). Monomer (m T The upper limit of the Tg of the homopolymer of each monomer used as is not particularly limited and may be, for example, 250°C or less, 200°C or less, or 150°C or less.

[0051] Monomer (m T Non-limiting specific examples of nitrogen atom-free monomers that can be used as ) include acrylic acid, methacrylic acid, methyl methacrylate, methacrylonitrile, acryloylmorpholine, acrylamide, isobornyl acrylate, isobornyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, adamantyl acrylate, tert-butyl methacrylate, etc. Preferred examples include acrylic acid (AA) and methyl methacrylate (MMA).

[0052] Monomer (m T The nitrogen atom-containing monomer content in ) may be, for example, 35 mol% or more, and from the viewpoint of easily achieving suitable film properties, it is appropriate to be 50 mol% or more, and preferably 60 mol% or more. In some embodiments, monomer (m T The nitrogen atom-containing monomer content in ) may be greater than 70 mol%, greater than 80 mol%, greater than 90 mol%, greater than 93 mol%, or 100 mol%. In some embodiments, the monomer (mT The nitrogen atom-containing monomer content in ) may be 85 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less.

[0053] In some embodiments, monomer (m T The nitrogen atom-containing monomer contained in ) contains at least acrylonitrile. In such an embodiment, the monomer (m T The proportion of acrylonitrile among the nitrogen atom-containing monomers contained in ) may be, for example, 25 mol% or more, 50 mol% or more, 70 mol% or more, 85 mol% or more, 95 mol% or more, or 100 mol%.

[0054] Monomer (m T In embodiments in which the monomer (m T The acrylonitrile content in ) may be, for example, 35 mol% or more, and from the viewpoint of easily achieving suitable film properties, it is appropriate to be 50 mol% or more, and preferably 60 mol% or more. In some embodiments, monomer (m T The acrylonitrile content in ) may be greater than 70 mol%, greater than 80 mol%, greater than 90 mol%, greater than 93 mol%, or 100 mol%. In some embodiments, the monomer (m T The acrylonitrile content in ) may be 85 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less.

[0055] The monomer components that make up polymer (A) are monomer (m T ) and monomers (m LIn embodiments including the above, the proportion of nitrogen atom-containing monomers in the total monomer components in which the homopolymer Tg is 90°C or higher may be, for example, 20 mol% or more, and from the viewpoint of facilitating the realization of suitable film properties, it is appropriate to be 25 mol% or more (for example, 28 mol% or more), preferably 30 mol% or more, may be 35 mol% or more, and may be 40 mol% or more. The technology disclosed herein can preferably be implemented in an embodiment in which the proportion of nitrogen atom-containing monomers in the total monomer components constituting polymer (A) in which the homopolymer Tg is 90°C or higher is greater than 50 mol%. Furthermore, from the viewpoint of the flexibility of the coating material, the proportion of nitrogen atom-containing monomers in the total monomer components in which the homopolymer Tg is 90°C or higher is appropriate to be 60 mol% or less, and preferably less than 60 mol%. In some embodiments, the proportion of nitrogen atom-containing monomers in the homopolymer Tg is 90°C or higher may be 57 mol% or less, or 56 mol% or less. The technology disclosed herein can also be implemented in embodiments in which the proportion of nitrogen atom-containing monomers having a Tg of 90°C or higher in the homopolymer is 53 mol% or less, 50 mol% or less, and even 40 mol% or less.

[0056] The monomer components that make up polymer (A) are monomer (m T ) and monomers (m LIn embodiments including the above, the acrylonitrile content in the total monomer components may be, for example, 20 mol% or more, and from the viewpoint of facilitating the realization of suitable film properties, it is appropriate to be 25 mol% or more (for example, 28 mol% or more), preferably 30 mol% or more, may be 35 mol% or more, and may be 40 mol% or more. The technology disclosed herein can preferably be implemented in embodiments in which the acrylonitrile content in the total monomer components constituting polymer (A) is greater than 50 mol%. Furthermore, from the viewpoint of the flexibility of the coating material, the acrylonitrile content is appropriate to be 60 mol% or less, and preferably less than 60 mol%. In some embodiments, the acrylonitrile content may be 57 mol% or less, or 56 mol% or less. The technology disclosed herein can also be implemented in embodiments in which the acrylonitrile content is 53 mol% or less, 50 mol% or less, and even 40 mol% or less.

[0057] The above monomer component (m T ) and the above monomer (m L ) molar ratio (m T / m L ) is not particularly limited and may be, for example, around 0.05 to 3.00, or around 0.10 to 2.00. In some embodiments, the above ratio (m T / m L The ratio (m) is appropriately set to, for example, 0.60 to 1.50 or 0.8 to 1.5. A polymer (A) composed of monomer components of such a composition is likely to yield a coating material exhibiting the preferred storage modulus described later. In some embodiments, the above ratio (m) is appropriate. T / m L The ratio (m) is preferably less than 1.5, more preferably 1.4 or less, may be 1.35 or less, may be 1.30 or less, or may be 1.25 or less. In some embodiments, the above ratio (m) T / m LThe ratio (m) is preferably 0.70 or higher, more preferably 0.75 or higher, may be 0.90 or higher, may be 1.0 or higher, or may be greater than 1.0. This makes it possible to realize a coating material that achieves a higher level of balance between good peelability from the coating film and good peelability. T / m L ) may be 1.1 or higher, 1.15 or higher, or 1.20 or higher.

[0058] The monomer components that make up polymer (A) are monomer (m T ) and monomers (m L Other monomers, i.e., homopolymers whose glass transition temperature is higher than -30°C and lower than 90°C (hereinafter referred to as monomers (m I ) may also include. Monomer (m I For example, monomers can be selected from the various monomers mentioned above, provided that the glass transition temperature of the homopolymer falls within the above range. I Monomers (m) can be used individually or in combination of two or more. I Non-limiting specific examples of monomers that can be used as ) include ethyl acrylate (EA), ethyl methacrylate, methyl acrylate (MA), n-butyl methacrylate, isobutyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, vinyl acetate, N-vinyl-2-pyrrolidone, etc.

[0059] Monomer (m I The amount used is calculated by taking the total amount of monomer components as 100 mol% and then using the monomer (m T ) and monomers (m L The amount can be appropriately set within a range less than or equal to the amount (mol%) excluding the amount of monomer (m IThe amount used should not exceed 80 mol% of the total monomer components (for example, not exceeding 40 mol%), it is advantageous for it not to exceed 30 mol%, it is preferable for it not to exceed 20 mol%, and it is more preferable for it not to exceed 15 mol%. The technology disclosed herein relates to monomer (m I This can preferably be carried out in which the amount of monomer (m) used is 0 mol% or more and less than 10 mol% of the total monomer components, for example, 0 mol% or more and less than 5 mol%. Here, monomer (m I The amount of monomer used is 0 mol% of the total monomer components, or at least intentionally, the monomer (m I This means not to use )

[0060] <Synthesis of polymer (A)> The method for obtaining polymer (A) from the monomer components described above is not particularly limited. For example, known polymerization methods such as emulsion polymerization, solution polymerization, bulk polymerization, and suspension polymerization can be appropriately employed. Alternatively, active energy ray irradiation polymerization, such as photopolymerization (typically carried out in the presence of a photopolymerization initiator) by irradiating with light such as UV, or radiation polymerization (carried out by irradiating with radiation such as beta rays or gamma rays), may be employed. In some preferred embodiments, polymer (A) is obtained by emulsion polymerization of monomer components having the above-described composition. As for the monomer supply method in the emulsion polymerization method, a batch supply method in which all monomer raw materials are supplied at once, a continuous supply (dropping) method, a divided supply (dropping) method, etc., can be appropriately employed. Some or all of the monomer components may be pre-mixed with water and an emulsifier to emulsify them, and the emulsion may be supplied to the polymerization vessel.

[0061] The polymerization temperature can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc. A polymerization temperature of approximately 20°C or higher is appropriate, preferably approximately 40°C or higher, more preferably approximately 50°C or higher, and may also be approximately 60°C or higher, approximately 65°C or higher, and even more preferably approximately 70°C or higher. Furthermore, a polymerization temperature of approximately 170°C or lower (typically approximately 140°C or lower) is appropriate, and preferably approximately 95°C or lower (for example, approximately 85°C or lower). In emulsion polymerization, it is preferable to set the polymerization temperature to approximately 95°C or lower (for example, approximately 85°C or lower).

[0062] The solvent used for solution polymerization (polymerization solvent) can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons), acetic acid esters such as ethyl acetate, and aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane are preferably used.

[0063] During polymerization, known or conventional thermal polymerization initiators or photopolymerization initiators may be used depending on the polymerization method and polymerization mode. Polymerization initiators can be used individually or in appropriate combinations of two or more types.

[0064] While not particularly limited, thermal polymerization initiators can be used, for example, azo polymerization initiators, peroxide initiators, redox initiators consisting of a combination of peroxide and reducing agent, substituted ethane initiators, etc. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, and 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride. Examples of peroxide initiators include persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, di-n-octanoyl peroxide, di(4-methylbenzoyl) peroxide, t-butyl peroxybenzoate, t-butyl peroxyisobutyrate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(2-ethylhexyl Examples include sil)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-hexylperoxy)cyclohexane, hydrogen peroxide, etc. Examples of redox initiators include combinations of peroxides and ascorbic acid (such as hydrogen peroxide and ascorbic acid), combinations of peroxides and iron(II) salts (such as hydrogen peroxide and iron(II) salts), and combinations of persulfates and sodium bisulfite.

[0065] While not particularly limited, the following can be used as photopolymerization initiators: ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like.

[0066] The amount of polymerization initiator used can be the usual amount depending on the polymerization method and polymerization mode, and is not particularly limited. For example, approximately 0.001 to 5 parts by weight (typically approximately 0.01 to 2 parts by weight, for example, approximately 0.01 to 1 part by weight) of polymerization initiator can be used per 100 parts by weight of the monomer to be polymerized.

[0067] During polymerization, various conventionally known chain transfer agents (which may also be understood as molecular weight modifiers or degree of polymerization modifiers) can be used as needed. Chain transfer agents can be used individually or in combination of two or more. Mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and thioglycolic acid can be used as chain transfer agents. Alternatively, chain transfer agents that do not contain sulfur atoms (non-sulfur chain transfer agents) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidenyl group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; and benzyl hydrogens such as diphenylbenzene and triphenylbenzene. When a chain transfer agent is used, the amount used can be approximately 0.01 to 1 part by weight per 100 parts by weight of the monomer component. The technology disclosed herein can also be preferably implemented in a form that does not use a chain transfer agent.

[0068] Emulsification polymerization is usually carried out in the presence of an emulsifier. The emulsifier used for emulsion polymerization is not particularly limited, and known anionic emulsifiers, nonionic emulsifiers, etc., can be used. The emulsifier can be used alone or in combination of two or more.

[0069] Non-limiting examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and sodium polyoxyethylene alkyl sulfosuccinate. Non-limiting examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene polyoxypropylene block polymers. Emulsifiers having reactive functional groups (reactive emulsifiers) may also be used. Examples of reactive emulsifiers include radical polymerizable emulsifiers, which have a structure in which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced into the above-mentioned anionic or nonionic emulsifiers.

[0070] The amount of emulsifier used in emulsion polymerization may be, for example, 0.2 parts by weight or more, 0.5 parts by weight or more, 1.0 part by weight or more, or 1.5 parts by weight or more, per 100 parts by weight of monomer components. From the viewpoint of suppressing foaming during emulsion polymerization and in compositions containing the obtained emulsion, in some embodiments, the amount of emulsifier used is usually appropriate to be 10 parts by weight or less, preferably 5 parts by weight or less, and may be 3 parts by weight or less, per 100 parts by weight of monomer components.

[0071] Emulsion polymerization may be carried out in the presence of a protective colloid. Examples of protective colloids include polyvinyl alcohol-based polymers such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; cellulose derivatives such as hydroxyethylcellulose, hydroxypropylcellulose, and carboxymethylcellulose salts; and natural polysaccharides such as guar gum. The degree of saponification of partially saponified polyvinyl alcohol is typically less than 95 mol%, but may also be less than 92 mol% or less than 90 mol%. There is no particular lower limit to the degree of saponification of partially saponified polyvinyl alcohol, but from the viewpoint of emulsion stability, it is appropriate to have a degree of 65 mol% or higher, preferably 70 mol% or higher, and more preferably 80 mol% or higher (e.g., 85 mol% or higher). Examples of the above-mentioned modified polyvinyl alcohol include anionic modified polyvinyl alcohol into which anionic groups such as carboxyl groups and sulfonic acid groups have been introduced; and cationic modified polyvinyl alcohol into which cationic groups such as quaternary ammonium salts have been introduced. The degree of saponification of the modified polyvinyl alcohol may be, for example, less than 98 mol%, but may also be less than 95 mol%, less than 92 mol%, or less than 90 mol%. Furthermore, the lower limit of the degree of saponification of the modified polyvinyl alcohol may be, for example, 55 mol% or more, and from the viewpoint of emulsion stability, 65 mol% or more is appropriate, 70 mol% or more is preferred, and 80 mol% or more (for example, 85 mol% or more) is more preferred. The protective colloid can be used alone or in combination of two or more types.

[0072] The amount of protective colloid used is appropriately about 0.1 parts by weight or more per 100 parts by weight of monomer component, preferably 0.5 parts by weight or more (for example, 0.7 parts by weight or more), and preferably 10 parts by weight or less, and preferably 5 parts by weight or less (for example, 3 parts by weight or less, or 2 parts by weight or less). The protective colloid is preferably used in combination with the emulsifier as described above, but is not limited thereto, and the protective colloid may be used without an emulsifier. For example, emulsion polymerization can be carried out by placing water and protective colloid in a polymerization container, and supplying an emulsion to the polymerization container in which some or all of the monomer component has been pre-mixed with water and an emulsifier. When using an anionic protective colloid (for example, anionic modified polyvinyl alcohol) in combination with an emulsifier, it is preferable to use one or more types selected from the group consisting of anionic emulsifiers and nonionic emulsifiers as the emulsifier, from the viewpoint of polymerization stability, etc.

[0073] In some preferred embodiments, emulsion polymerization is carried out in the presence of a polyvinyl alcohol-based polymer. The aqueous emulsion of polymer (A) obtained by such emulsion polymerization tends to exhibit a viscosity-enhancing effect when a thickening agent is added. By using such an aqueous emulsion of polymer (A), a coating composition exhibiting good viscosity characteristics suitable for slot die coating can be suitably prepared. A preferred example of the polyvinyl alcohol-based polymer is anionically modified polyvinyl alcohol. For example, sulfonic acid group-modified polyvinyl alcohol or carboxylated polyvinyl alcohol can be preferably used. A polyvinyl alcohol-based polymer and an emulsifier may also be used in combination.

[0074] <Coating composition> The coating compositions disclosed herein include one of the above-described polymers (A) as a base polymer. The form of the coating composition is not particularly limited and may include, for example, an aqueous emulsion type composition in which polymer (A) is dispersed in an aqueous solvent, or a solvent type composition in which polymer (A) is dissolved in an organic solvent. From the viewpoint of environmental hygiene, an aqueous emulsion type coating composition is preferred. The following description will mainly focus on aqueous emulsion type coating compositions, but the intention is not to limit the coating compositions disclosed herein to aqueous emulsion type.

[0075] In an aqueous emulsion-type coating composition, the aqueous solvent refers to water or a mixed solvent having water as the main component (a component present in more than 50% by weight). The solvents other than water constituting this mixed solvent may be one or more selected from various organic solvents (such as lower alcohols) that can be uniformly mixed with water. The aqueous solvent in this specification typically has a water content of 90% by weight or more, preferably 95-100% by weight.

[0076] The coating compositions disclosed herein may optionally contain various additives. Examples of such additives include known thickeners, thixotropes, dispersants, defoamers, and inorganic powders. For example, an aqueous emulsion type coating composition can be prepared by blending various additives with an aqueous emulsion (polymerization reaction solution) of polymer (A) obtained by the emulsion polymerization described above. Alternatively, the aqueous emulsion of polymer (A) may be used as is, or the aqueous emulsion may be pH-adjusted (for example, by adding aqueous ammonia to adjust the pH to about 6-8) and / or its concentration adjusted (for example, by adding water to adjust the solid content to about 40-60% by weight) and used as the coating composition.

[0077] By incorporating inorganic powder into a coating composition, a coating material containing inorganic powder is formed. With such a coating material, the inorganic powder can block light such as ultraviolet rays, thereby suppressing photodegradation of the coating material itself and the coating film protected by the coating material. Suitable inorganic powders include oxides such as titanium dioxide, zinc oxide, magnesium oxide, alumina, and silica; carbonates such as calcium carbonate; sulfates such as barium sulfate; and the like. Inorganic powders that can color the coating protective coating material white are preferred. With a white coating protective coating material, for example, the deterioration of the coating material and the coating film can be better suppressed by suppressing the temperature rise caused by sunlight irradiation.

[0078] The amount of inorganic powder used per 100 parts by weight of polymer (A) can be, for example, 0.5 parts by weight or more, and from the viewpoint of light shielding effect, it is appropriate to use 1 part by weight or more, preferably 2 parts by weight or more, more preferably 3 parts by weight or more, and may also be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, or 40 parts by weight or more (for example, 45 parts by weight or more). Furthermore, the amount of inorganic powder used per 100 parts by weight of polymer (A) can be, for example, 100 parts by weight or less, and from the viewpoint of the strength and film-forming properties of the coating material, it is appropriate to use 80 parts by weight or less, advantageous to use 60 parts by weight or less, preferably 50 parts by weight or less, and may also be 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, or 10 parts by weight or less.

[0079] In several preferred embodiments, the inorganic powder contains at least titanium dioxide (TiO2). Titanium dioxide may be used in combination with one or more other inorganic powders (e.g., calcium carbonate). The type of titanium dioxide is not particularly limited, and any crystalline form of titanium dioxide, such as rutile, anatase, or brookite, can be used. Rutile titanium dioxide is preferred. Titanium dioxide with a coating applied to the particle surface may also be used. The material used to coat the titanium dioxide particles is not particularly limited and can be an inorganic oxide such as silica, alumina, or zinc oxide. A preferred example is a highly weather-resistant type of titanium dioxide (typically rutile titanium dioxide) with the particle surface coated with Si-Al2O3 or the like.

[0080] The amount of titanium dioxide used per 100 parts by weight of polymer (A) can be, for example, 0.1 parts by weight or more, and from the viewpoint of light shielding effect, it is appropriate to use 0.5 parts by weight or more, preferably 1 part by weight or more, more preferably 2 parts by weight or more, and may also be 3 parts by weight or more. In addition, the amount of titanium dioxide used per 100 parts by weight of polymer (A) can be, for example, 30 parts by weight or less, appropriate to use 20 parts by weight or less, preferably 15 parts by weight or less, may also be 10 parts by weight or less, and may also be 8 parts by weight or less.

[0081] The average particle size of the inorganic powder is not particularly limited. For example, from the viewpoint of obtaining a good light shielding effect, the average particle size of the inorganic powder is preferably 150 nm or more, more preferably 180 nm or more, and may also be 220 nm or more, or 250 nm or more. On the other hand, from the viewpoint of dispersibility in the resin component, the average particle size of the inorganic powder is suitable to be 3000 nm or less (e.g., 2000 nm or less), preferably 1500 nm or less, more preferably 1000 nm or less (e.g., 800 nm or less), and may also be 500 nm or less, 400 nm or less, or 350 nm or less. For example, titanium oxide particles with an average particle size of about 250 to 350 nm can be preferably used.

[0082] Thickening agents can be used to adjust the viscosity properties of the coating composition. Known thickening agents such as urethane-based thickening agents, cellulose-based thickening agents, polyether-based thickening agents, and acrylic-based thickening agents can be used. Thickening agents can be used individually or in appropriate combinations of two or more. Examples of commercially available urethane-based thickeners include BYK's product names "RHEOBYK-H 3300VF," "RHEOBYK-T 1010," and "RHEOBYK-L 1400," ADEKA's product names "Adekanol UH-450VF," "Adekanol UH-420," "Adekanol UH-462," "Adekanol UH-472," "Adekanol UH-540," "Adekanol UH-756VF," and "Adekanol UH-814N," and Sunnopco's product names "SN Thickener 612," "SN Thickener 621N," "SN Thickener 625N," "SN Thickener 627N," and "SN Thickener 660T." In some embodiments, urethane association type thickeners can be preferably used as urethane-based thickeners. Suitable examples of urethane-associated thickeners include BYK's product names "RHEOBYK-H 3300VF," "RHEOBYK-T 1010," and "RHEOBYK-L 1400," and ADEKA's product names "Adekanol UH-450VF," "Adekanol UH-420," and "Adekanol UH-756VF."

[0083] Examples of cellulose-based thickeners include hydroxyethylcellulose, carboxymethylcellulose, and methylcellulose. A commercially available example is "SANHEC L" manufactured by Sansho Co., Ltd. Examples of polyether-based thickeners include polyethylene glycol, polyether dialkyl esters, polyether dialkyl ethers, and polyether epoxy modified products. A commercially available example is "POLYOX WSR N-80" manufactured by Dow Chemical. Examples of acrylic thickeners include acrylic acid polymers such as sodium polyacrylate. Commercially available products include, for example, "Primal ASE-60," "Primal TT-615," and "Primal RM-5" from Rohm & Haas, and "SN Thickener 613," "SN Thickener 618," "SN Thickener 630," "SN Thickener 634," and "SN Thickener 636" from Sunnopco.

[0084] The amount of thickener used is not particularly limited and can be adjusted as appropriate to obtain the desired viscosity characteristics. From the viewpoint of suppressing excessive influence on film properties, in some embodiments, the amount of thickener used per 100 parts by weight of polymer (A) is appropriate to be 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less (e.g., 3 parts by weight or less), may be 2.5 parts by weight or less, 2 parts by weight or less, 1.0 part by weight or less, or 0.50 parts by weight or less. The lower limit of the amount of thickener used is not particularly limited and may be 0.01 parts by weight or more, 0.05 parts by weight or more, 0.1 parts by weight or more (e.g., 0.10 parts by weight or more), or 0.20 parts by weight or more per 100 parts by weight of polymer (A).

[0085] Thixotropes can be useful for adjusting the viscosity properties of coating compositions. Inorganic materials such as bentonite, modified bentonite, montmorillonite, and hectorite can be used as thixotropes. Thixotropes can be used individually or in combination of two or more. The amount of thixotropin used is not particularly limited and can be adjusted as appropriate to obtain the desired viscosity characteristics. From the viewpoint of suppressing excessive influence on film properties, in some embodiments, the amount of thixotropin used per 100 parts by weight of polymer (A) is appropriate to be 10 parts by weight or less, preferably 5 parts by weight or less, and may also be 3 parts by weight or less, 2.5 parts by weight or less, or 2 parts by weight or less. The lower limit of the amount of thixotropin used is not particularly limited and may be 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more per 100 parts by weight of polymer (A). Alternatively, no thixotropin may be used.

[0086] The thixotropic agent may also function as a thickening agent. The thickening agents and thixotropic agents described above may be used in combination, or either one may be used alone. When the thickening agents and thixotropic agents are used in combination, the total amount used may be, for example, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 2.5 parts by weight or less, 1.5 parts by weight or less, or 1.0 part by weight or less per 100 parts by weight of polymer (A), or it may be 0.01 parts by weight or more, 0.05 parts by weight or more, 0.1 parts by weight or more (for example, 0.10 parts by weight or more), or 0.20 parts by weight or more.

[0087] Methods for applying the coating composition onto the coating film of an object to be protected include, for example, application by a coater such as a die coater or spray coater, roller application, dip coating, etc. The application by a die coater may be performed by a coating system including a robotic arm equipped with a slit die. For example, by controlling the robotic arm so that the slit die moves along the shape of the object to be protected while discharging the coating composition in a continuous liquid film (ribbon shape), the coating composition can be applied to the object to be protected efficiently and accurately, even if the object to be protected has a non-planar shape (for example, a complex three-dimensional shape such as the exterior panel of an automobile).

[0088] Drying the applied coating composition is preferably carried out under heating, from the viewpoint of improving the efficiency and precision of coating material formation. The drying temperature can be, for example, around 40°C to 100°C, and is usually preferably around 60°C to 90°C.

[0089] While not particularly limited, from the viewpoint of ease of coating and film thickness control, the solid content of the coating composition is suitable to be about 25 to 75% by weight, and preferably about 30 to 70% by weight (for example, about 45 to 55% by weight). The solid content can be adjusted by the amount of solvent (for example, aqueous solvent) used. For example, the solid content of the coating composition can be adjusted by adjusting the amount of water used in emulsion polymerization or by adding water after the emulsion polymerization is completed.

[0090] The thickness of the protective coating material is not particularly limited, but from the viewpoint of enhancing the protective effect, it is appropriate to have a thickness of 20 μm or more, and from the viewpoint of strength and peelability, it is preferable to have a thickness of 50 μm or more, and more preferably 70 μm or more (for example, 85 μm or more). The thickness of the coating material can be adjusted by the amount of coating composition applied and the solid content. From the viewpoint of drying properties and preventing sagging of the applied composition, the thickness of the coating material is appropriate to have a thickness of 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less.

[0091] (BH viscosity) In some embodiments, the viscosity V1 of the coating composition, as measured by a BH-type viscometer at 2 rpm, is appropriately 20 Pa·s or higher, preferably 40 Pa·s or higher, and more preferably 55 Pa·s or higher. As the viscosity V1 measured under such low shear rate conditions increases, the anti-sagging properties of the coating composition applied to the object to be protected (e.g., anti-sagging properties when applied to a vertical surface) tend to improve. On the other hand, from the viewpoint of the defoaming and leveling properties of the coating composition, the viscosity V1 of the coating composition is appropriately 200 Pa·s or less, preferably 150 Pa·s or less, and more preferably 100 Pa·s or less (e.g., 80 Pa·s or less).

[0092] The viscosity V2 of the above coating composition, as measured by a BH-type viscometer at 20 rpm, is not particularly limited and may be, for example, around 5 Pa·s to 50 Pa·s. When viscosity V2 is within this range, the viscosity V1 described above is easily obtained. The viscosity of the coating composition as measured by a BH-type viscometer (BH viscosity) is measured by a BH-type viscometer at 30°C under conditions of 2 rpm and 20 rpm. The rotor used for measurement is appropriately selected according to the viscosity. For example, measurement can be performed using a No. 6 rotor, and if the use of a No. 6 rotor is inappropriate, measurement can be performed using another rotor of a suitable number.

[0093] The ratio of viscosity V1 to viscosity V2 (hereinafter also referred to as the "Ti value") may be, for example, 2.0 or more, preferably 3.0 or more, and more preferably 3.5 or more. Furthermore, the Ti value may be, for example, 9.0 or less, preferably 8.0 or less, more preferably 7.0 or less, and may also be 6.0 or less, or 5.5 or less. A coating composition having such a Ti value is likely to yield coating properties suitable for slot die coating.

[0094] (Rheometer viscosity) In some embodiments, the above coating composition has a shear rate of 100 sec measured by a cone-plate rheometer. -1 The viscosity V3 is preferably 1.0 Pa·s or higher, more preferably 1.3 Pa·s or higher, and may also be 1.5 Pa·s or higher, 2.0 Pa·s or higher, or 2.3 Pa·s or higher. By setting the viscosity V3 measured under such high shear rate conditions to a predetermined level or higher, the coating properties (die coating properties) by the slot die can be improved. There is no particular upper limit to the viscosity V3, but from the viewpoint of ease of compatibility with defoaming properties and ease of liquid transfer, it is appropriate to be 15 Pa·s or lower, preferably 10 Pa·s or lower, and may also be 8.5 Pa·s or lower, or 6.0 Pa·s or lower. The viscosity of the coating composition measured using the above-mentioned rheometer (rheometer viscosity) was determined using a commercially available rheometer (for example, Haacke's "Rheo Stress 1" rheometer viscometer or equivalent) with a cone-type rotor (Cone Diameter: 35 mm, Cone Angle: 0.5 deg.) at 30°C, with a shear rate of 0.1 to 2000 sec. -1 From the viscosity when continuously changed, the shear rate 100 sec -1 The viscosity can be measured by reading the viscosity in the sample.

[0095] <Coating material for protective coating of paint film> The coating protective coating material disclosed herein can be formed using the coating composition described above. For example, the coating composition is applied (preferably by a slot die) onto the coating of an object to be protected and dried. This makes it possible to provide a coating protective coating material 10 formed from the coating composition on the coating 22 of an object to be protected 20 having a coating 22, for example, as shown in Figure 1.

[0096] In some embodiments, the above-mentioned coating material may have a storage modulus (G'(70)) of 0.20 MPa or higher at 70°C. From the viewpoint of peelability, it is appropriate for G'(70) to be 0.30 MPa or higher, preferably 0.40 MPa or higher, and preferably 0.45 MPa or higher. A coating material with a G'(70) above the predetermined level will not become excessively soft even at temperatures higher than room temperature, such as when the protected object to which the coating material is applied is placed outdoors in the summer, and will be able to be properly peeled off the coating film. From the viewpoint of improving peelability at high temperatures, in some embodiments, it is advantageous for G'(70) to be 0.50 MPa or higher, preferably 0.70 MPa or higher, and may also be 1.0 MPa or higher, or 1.2 MPa or higher. The upper limit of G'(70) is not particularly limited, and may be, for example, 5 MPa or less, preferably 3 MPa or less, may also be 2.5 MPa or less, or 2.0 MPa or less. In some embodiments, G'(70) may be 1.5 MPa or less, 1.30 MPa or less, or 1.2 MPa or less (for example, 1.20 MPa or less). It is preferable that G'(70) is not too high from the viewpoint of suppressing marks on the coating film.

[0097] In some embodiments, the storage modulus (G'(23)) of the coating material at 23°C may be, for example, 100 MPa or more. From the viewpoint of peelability, G'(23) is preferably 150 MPa or more, more preferably 180 MPa or more, and may also be 230 MPa or more, 250 MPa or more, 300 MPa or more, 450 MPa or more, or 500 MPa or more. Coating materials with a G'(23) above the predetermined level tend not to tear or stretch excessively when peeled off from the coating film at room temperature. This is advantageous from the viewpoint of improving peelability. In some embodiments, G'(23) is appropriately approximately 1000 MPa or less. Having a G'(23) that is not too high is advantageous from the viewpoint of suppressing marks on the coating film. It is also preferable from the viewpoint of peelability because it is easier to perform an operation to initiate peeling when removing the coating material from the coating film (for example, scratching the edge of the coating material with a fingernail to lift it away from the coating film). In some embodiments, G'(23) may be 800 MPa or less, 700 MPa or less, 600 MPa or less, 500 MPa or less, 450 MPa or less, or 400 MPa or less.

[0098] In some embodiments, the storage modulus of the coating material at -30°C (G'(-30)) may be, for example, approximately 2400 MPa or less. From the viewpoint of preventing marks, it is appropriate for G'(-30) to be 2300 MPa or less, advantageous for it to be 2200 MPa or less (e.g., less than 2200 MPa), preferred for it to be 2000 MPa or less, more preferably for it to be 1900 MPa or less, and may also be 1800 MPa or less, 1700 MPa or less, or 1600 MPa or less. The lower limit of G'(-30) is not particularly limited. From the viewpoint of making it easier to form a coating material in which G'(70) and G'(23) are within an appropriate range, in some embodiments, it is appropriate for G'(-30) to be 500 MPa or more, preferred for it to be 800 MPa or more, more preferably for it to be 1000 MPa or more, may also be 1200 MPa or more, may also be 1300 MPa or more, or may also be 1400 MPa or more.

[0099] The storage modulus of the coating material (G'(70), G'(23), G'(-30)) is measured by the method described in the examples below.

[0100] In some embodiments of the coating materials disclosed herein, it is appropriate, preferably 30°C or higher, and more preferably 34°C or higher, for the coating material to have a glass transition temperature (hereinafter also referred to as "RSA-Tg") determined as the peak top temperature of tanδ in viscoelasticity measurements. Furthermore, RSA-Tg may be, for example, 50°C or lower, 45°C or lower, or 43°C or lower (for example, 41°C or lower). With coating materials having an RSA-Tg within the above range, it is easy to obtain coating materials in which 1 or 2 or more of the above-mentioned G'(70), G'(23), and G'(-30) are within an appropriate range.

[0101] In some embodiments of the coating material, it is appropriate that the glass transition temperature (hereinafter also referred to as "RSA-Tg(G)"), which is determined as the temperature corresponding to the inflection point of the loss modulus G'' in viscoelasticity measurement, is 5°C or higher, preferably 15°C or higher, and more preferably 20°C or higher. Furthermore, RSA-Tg(G) may be, for example, 40°C or lower, 35°C or lower, or 30°C or lower (for example, 25°C or lower). With a coating protective material in which RSA-Tg(G)'' is within the above range, it is easy to obtain a coating protective material that satisfies the above-mentioned G'(23) and G'(70). The RSA-Tg(G)'' of Examples B1 to B6 in the embodiments described later were as follows: B1: 20°C, B2: 20°C, B3: 20°C, B4: 20°C, B5: 23°C, B6: 23°C.

[0102] The coating material disclosed herein is suitable to have a breaking strength of 12 N / 25 mm or more, measured by the tensile test described in the examples below, which is advantageous to be 15 N / 25 mm or more, preferably 20 N / 25 mm or more, and may also be 25 N / 25 mm or more, 30 N / 25 mm or more, or 35 N / 25 mm or more. The coating material disclosed herein preferably has a fracture elongation of 100% or more, is advantageous if it is 150% or more, is preferable if it is 200% or more, may be 220% or more, or may be 250% or more, as measured by the tensile test described in the examples later. Such a coating material can distribute stress by deforming appropriately when peeled off from the coating film, thereby suppressing the tearing of the coating material due to localized stress concentration. There is no particular upper limit to the fracture elongation, but for example, it is appropriate if it is 500% or less, may be 450% or less, or may be 400% or less. Having an elongation at fracture that is not too large can be advantageous from the viewpoint of improving work efficiency during peeling.

[0103] From the viewpoint of obtaining good peelability, the coating material disclosed herein is preferably such that the peel strength measured by the method described in the examples below is less than 4.0 N / 25 mm, and is advantageous if it is less than 2.5 N / 25 mm. In some embodiments, the above peel strength is preferably 2.0 N / 25 mm or less, more preferably 1.5 N / 25 mm or less, may also be 1.2 N / 25 mm or less, or 1.0 N / 25 mm or less. A low peel strength is preferable from the viewpoint of reducing the workload during peeling, and is also advantageous from the viewpoint of suppressing tearing or chipping of the coating material during peeling. Furthermore, from the viewpoint of obtaining appropriate adhesion to the coating film, the above peel strength is preferably 0.1 N / 25 mm or more, preferably 0.2 N / 25 mm or more, may also be 0.3 N / 25 mm or more, may also be 0.5 N / 25 mm or more, or may be 0.7 N / 25 mm or more. It is preferable that the above-mentioned peel strength is not too low, from the viewpoint of preventing the coating material from unintentionally peeling off the coating film during the protective period of the coating film.

[0104] In some embodiments, the breaking strength [N / 25mm] is appropriately 5 times or more the peel strength [N / 25mm], advantageously 8 or more, and preferably 10 or more. A larger ratio of breaking strength to peel strength tends to reduce the likelihood of tearing or chipping when peeling from the protected coating. From this viewpoint, the ratio of breaking strength to peel strength may be 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, or 40 or more. There is no particular upper limit to the ratio of breaking strength to peel strength, but from the viewpoint of easily achieving both appropriate peel strength and good resistance to leaving marks, it is appropriate to be 100 or less, may be 80 or less, 70 or less, or 60 or less.

[0105] This specification provides an aqueous emulsion in which any polymer (A) disclosed herein is dispersed in an aqueous solvent, which can be used as a component of any coating composition disclosed herein to produce said coating composition. The coating composition disclosed herein can be suitably produced by adding and mixing the above-mentioned components (e.g., thickeners, inorganic powders, thixotropes) as needed to such aqueous emulsion. Alternatively, the aqueous emulsion may be used as is as the coating composition.

[0106] This specification provides a method for protecting a coating film, comprising: preparing one of the coating compositions disclosed herein; applying the coating composition onto a coating film on an object to be protected having a coating film; and drying the coating composition to form a coating protective coating material that temporarily protects the coating film. One embodiment of the above coating protection method will be described with reference to Figure 2. Specifically, one of the coating compositions disclosed herein is prepared (step S10). This coating composition is applied to the coating of an object to be protected (for example, by applying with a slot die) (step S20). The applied coating composition is dried to form a coating protective coating material that temporarily protects the coating (step S30). By providing a coating material on the coating in this way, the coating can be protected from damage and deterioration. The coating material, having completed its protective role, is peeled off from the coating at a desired timing (for example, by peeling) (step S40).

[0107] The matters disclosed in this specification include the following: [1] A protective coating material formed from a liquid coating composition, The above coating composition contains polymer (A), which is a polymer of monomer components including an acrylic monomer, as a base polymer. The SP value of the above polymer (A) is 9.8 (cal / cm³). 3 ) 1 / 2 That is all, and The above polymer (A) is a protective coating material in which the glass transition temperature calculated based on the composition of the monomer components constituting the polymer (A) is 0°C or lower. [2] The coating protective material described in [1] above, wherein the acid value of the polymer (A) is 15 mg KOH / g or less. [3] A protective coating material for coating films as described in [1] or [2] above, wherein the storage modulus of elasticity at 70°C is 0.40 MPa or higher. [4] The coating protective material according to any one of [1] to [3] above, wherein the monomer component constituting the polymer (A) includes a nitrogen atom-containing monomer. [5] The above nitrogen atom-containing monomer contains acrylonitrile, the coating protective material according to any one of [1] to [4] above. [6] The polymer (A) is a protective coating material according to any one of [1] to [5] above, wherein the polymer (A) has a glass transition temperature of -20°C or higher, calculated based on the composition of the monomer components constituting the polymer (A). [7] The polymer (A) comprises a monomer component comprising an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms at its ester terminus and a carboxyl group-containing monomer, as described in any of [1] to [6] above. [8] The coating composition is an aqueous emulsion composition in which the polymer (A) is dispersed in an aqueous solvent, the coating protective coating material according to any one of [1] to [7] above. [9] A protective coating material for paint films according to any of [1] to [8] above, which contains a polyvinyl alcohol-based polymer.

[10] A protective coating material for coatings according to any of [1] to [9] above, which contains a thickening agent.

[11] Further comprising inorganic powder. A protective coating material for coating films according to any of [1] to

[10] above.

[12] The inorganic powder is titanium dioxide, and the coating material is the coating protective material described in

[11] above.

[13] A protective coating material according to any of [1] to

[12] above, having a thickness of 20 μm or more and 300 μm or less.

[14] A coating composition used to form a protective coating material for a coating film as described in any of [1] to

[13] above.

[0108]

[15] A coating composition comprising a polymer (A), which is a polymer of monomer components including an acrylic monomer, as a base polymer, The SP value of the above polymer (A) is 9.8 (cal / cm³). 3 ) 1 / 2 That is all, and The above polymer (A) is a coating composition in which the glass transition temperature calculated based on the composition of the monomer components constituting the polymer (A) is 0°C or lower.

[16] The coating composition according to

[15] above, wherein the acid value of the polymer (A) is 15 mg KOH / g or less.

[17] The coating composition according to

[15] or

[16] above, wherein the storage modulus at 70°C is 0.40 MPa or more.

[18] The coating composition according to any one of

[15] to

[17] above, wherein the monomer component constituting the polymer (A) includes a nitrogen atom-containing monomer.

[19] The coating composition according to any one of

[15] to

[18] above, wherein the polymer (A) has a glass transition temperature of -20°C or higher, calculated based on the composition of the monomer components constituting the polymer (A).

[20] The coating composition according to any one of

[15] to

[19] above, wherein the monomer component constituting the polymer (A) comprises an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms at its ester terminus and a carboxyl group-containing monomer.

[21] The coating composition according to any one of

[15] to

[20] above, wherein the polymer (A) is dispersed in an aqueous solvent in an aqueous emulsion.

[22] The coating composition according to any one of

[15] to

[21] above, wherein the polymer (A) is emulsion polymerized in the presence of a protective colloid.

[23] The coating composition according to

[22] above, wherein the protective colloid is a polyvinyl alcohol-based polymer.

[24] A coating composition according to any one of

[15] to

[23] above, which contains a thickening agent.

[25] Further comprising inorganic powder. The coating composition according to any one of

[15] to

[24] above.

[26] The coating composition according to

[25] above, wherein the inorganic powder contains titanium dioxide.

[0109]

[27] Prepare a coating composition as described in any of

[15] to

[26] above. Applying the above coating composition onto the coating of an object to be protected that has a coating, and The above coating composition is dried to form a protective coating material that temporarily protects the above coating film. A coating protection method including the following.

[28] The coating protection method according to

[27] above, wherein the coating composition is applied by a slot die. [Examples]

[0110] The following describes several experimental examples related to the present invention, but the present invention is not intended to be limited to these specific examples. In the following description, "parts" and "%" used to express amounts and content are based on weight unless otherwise specified. Also, unless otherwise specified, the amount of each material used is based on the amount of active ingredient.

[0111] Experimental Example 1 <Preparation of coating composition> (Example A1) A monomer emulsion was prepared by mixing 66.3 parts (52 mol%) of n-butyl acrylate (BA), 15.8 parts (30 mol%) of acrylonitrile (AN), 17.9 parts (18 mol%) of methyl methacrylate (MMA), 0.05 parts of n-lauryl mercaptan, 2 parts of polyoxyethylene sodium lauryl sulfate (Kao Corporation, product name "Latemul E118B"), and 40 parts of ion-exchanged water, and emulsifying the mixture in an emulsifier (homomicker) while purging with nitrogen. Fifty parts of deionized water were placed in a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer. One part of anionically modified polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosenex L-3266"; saponification degree 86.5-89.0 mol%) was added, and the mixture was dissolved at room temperature while introducing nitrogen gas. The temperature was then raised to 60°C, and 0.1 parts of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (Wako Pure Chemical Industries, Ltd., trade name "VA-057") was added as a polymerization initiator. While maintaining the liquid temperature in the reaction vessel at around 60°C, the monomer emulsion was added over 3 hours to carry out the polymerization reaction. After the addition of the monomer emulsion was completed, the mixture was maintained at the same temperature for another 3 hours to mature. After cooling the system to room temperature, the pH was adjusted to 7.5 by adding 10% ammonium water to obtain an aqueous emulsion of polymer A1, which is a polymer of the above monomers. This aqueous emulsion was used as the coating composition in this example.

[0112] (Example A2~A10) Aqueous emulsions (coating compositions) of polymers A2 to A10 for each example were obtained in the same manner as in Example 1, except that the type and amount of monomer used were changed as shown in Table 1. In Table 1, "VAc" represents vinyl acetate and "AA" represents acrylic acid.

[0113] <Measurement and Evaluation> [Tensile test] A painted steel plate, coated with an acid epoxy cross-linked acrylic paint (manufactured by Kansai Paint Co., Ltd., product name "KINO1210TW"), was held horizontally with the painted surface facing upwards. The coating composition for each example was applied to the painted surface (on the paint film) of the painted steel plate using an applicator manufactured by TP Giken Co., Ltd., and dried at 80°C for 3 minutes to form a film (paint film protective coating material). The amount of coating composition applied was set so that the thickness in terms of solid content was 100 μm. The formed film was peeled from the painted steel plate at room temperature and cut into strips 25 mm wide and 100 mm long to prepare measurement samples for tensile testing. Under conditions of 23°C and 50% RH, the above-mentioned sample was placed in a tensile testing machine (Shimadzu Corporation, machine name "Tensilon"), and a tensile test was performed at a gauge length of 50 mm and a tensile speed of 0.3 m / min to measure the breaking strength [N / 25 mm] and elongation at breaking. The results are shown in Table 1.

[0114] [Measurement of storage modulus] Using the coating composition for each example, a 100 μm thick film was formed on the painted steel plate in the same manner as the film preparation for the tensile test described above. The formed film was peeled from the painted steel plate at room temperature, and multiple films were stacked and integrated under pressure to produce a laminated film with a thickness of approximately 1 mm. A measurement sample was prepared by punching this laminated film into a 7.9 mm diameter disc shape. This sample was sandwiched between parallel plates, and the viscoelasticity was measured using a viscoelasticity tester (TA Instruments, name "ARES G2") in shear mode while applying a shear strain at a frequency of 1 Hz over a temperature range of -70 to 150°C at a heating rate of 5°C / min. The storage modulus G' at each temperature was determined. The results are shown in Table 1.

[0115] [Acid value measurement] Using the coating compositions for each example, a 100 μm thick film was formed on the coated steel sheet in the same manner as the film preparation for the tensile test described above. The formed film was peeled from the coated steel sheet at room temperature, and the resulting mixture was placed in chloroform and allowed to stand for 12 hours. The mixture was then filtered, and substances with a weight-average molecular weight of 10,000 or more (measured by GPC) were used as samples. The acid value was measured according to the potentiometric titration method specified in JIS K0070-1992. Specifically, 50 mL of a solvent obtained by mixing diethyl ether and ethanol in a volume ratio of 4:1 was added to the precisely weighed sample and completely dissolved. Phenolphthalein solution was then added as an indicator to prepare the measurement solution. The measurement solution was subjected to potentiometric titration with a 0.1 mol / L potassium hydroxide ethanol solution, and the inflection point of the resulting titration curve was taken as the endpoint. The acid value was calculated using the following formula. The results are shown in Table 1. Acid value (mgKOH / g)=(B×F×5.611) / S B: Volume (mL) of 0.1 mol / L potassium hydroxide ethanol solution added at the endpoint. F: 0.1 mol / L potassium hydroxide ethanol solution (1.0) S: Sample volume (g)

[0116] [Peel strength] Using the coating composition described in each example, a 100 μm thick film was formed on the coated steel sheet in the same manner as the film preparation for the tensile test described above. The coated steel sheet was then placed in a constant temperature chamber at 70°C and kept there for 7 days. After removing the coated steel sheet from the constant temperature chamber and keeping it in an environment of 23°C and 50% RH for at least 30 minutes, two straight cuts (25 mm apart) and a cut perpendicular to the first cut were made in the film on the coating. The film was partially peeled off from the latter cut and set in a tensile testing machine (Shimadzu Corporation, machine name "Tensilon"), and the peel strength [N / 25 mm] of the film from the coated steel sheet was measured by peeling it in the 180-degree direction at a tensile speed of 0.3 m / min. The results are shown in Table 1.

[0117] [Anti-marking properties] Using the coating composition for each example, a 100 μm thick film was formed on the approximate center of the coated steel sheet in the same manner as in the film preparation for the tensile test described above. Next, the coated steel sheet was placed in a 70°C constant temperature chamber and held for 7 days. After removing the coated steel sheet from the constant temperature chamber and holding it in an environment of 23°C and 50% RH for 30 minutes or more, the film was peeled off the coated steel sheet, and the appearance of the coating in the area where the film had been formed was visually observed. Based on the results, the resistance to marks was evaluated on the following three levels. A higher score indicates better resistance to marks. The results are shown in Table 1. 3 points: Marks are not acceptable. Two points: A slight residue may be visible immediately after removing the film, but it will disappear naturally if left at room temperature. 1 point: Clear marks were observed, and the marks did not disappear even when left at room temperature.

[0118] [Table 1]

[0119] As shown in Table 1, the films formed by Examples A1 to A8 all had a peel strength of less than 4 N / 25 mm, indicating good peelability from the coating. Furthermore, these films all exhibited good resistance to leaving marks. Of the films in Examples A1 to A8, the film related to Example A5 had a breaking strength / peel strength ratio of 9, while all others were 10 or higher. In particular, the films in Examples A2 to A4 had low peel strength and a breaking strength / peel strength ratio of 35 or higher, demonstrating excellent peelability. On the other hand, the films formed from the coating compositions of Examples A9 and A10 could not achieve both good peelability and good resistance to leaving marks.

[0120] Experimental Example 2 <Preparation of coating composition> (Example B1) The coating composition of Example A1, prepared in Experimental Example 1, was modified by adding the amounts shown in Table 1 for 100 parts of polymer A1 contained in the composition to an antifoaming agent (manufactured by Kusumoto Chemical Co., Ltd., trade name "DISPARLON AQ7533") and a thickening agent (urethane association type thickening agent manufactured by ADEKA, trade name "ADEKA UH-756VF") to obtain the coating composition of this example.

[0121] (Example B2) To the coating composition of Example A1 prepared in Experimental Example 1, the following amounts were added per 100 parts of polymer A1 contained in the composition: titanium dioxide (rutile-type titanium dioxide manufactured by Ishihara Sangyo Co., Ltd., trade name "TIPAQUE CR-95", average particle size 280 nm), a dispersant (manufactured by BYK, trade name "DISPERBYK-2015"), an antifoaming agent (manufactured by Kusumoto Kasei Co., Ltd., trade name "DISPARLON AQ7533"), and a thickener (urethane-associated thickener manufactured by ADEKA, trade name "ADEKA UH-756VF"), as shown in Table 1, to obtain the coating composition according to this example.

[0122] (Example B3) To the coating composition of Example A1 prepared in Experimental Example 1, the following amounts were added per 100 parts of polymer A1 contained in the composition: titanium dioxide (rutile-type titanium dioxide manufactured by Ishihara Sangyo Co., Ltd., trade name "TIPAQUE CR-95", average particle size 280 nm), calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., trade name "Softon 3200"), dispersant (manufactured by BYK, trade name "DISPERBYK-2015"), defoaming agent (manufactured by Kusumoto Kasei Co., Ltd., trade name "DISPARLON AQ7533"), and thickener (urethane-associated thickener manufactured by ADEKA, trade name "ADEKA UH-756VF"), as shown in Table 1, to obtain the coating composition according to this example.

[0123] (Example B4) The coating composition according to this example was obtained in the same manner as in Example B3, except that the amounts of calcium carbonate and dispersant were as shown in Table 1.

[0124] (Example B5, B6) The coating compositions for each example were obtained in the same manner as in Examples B2 and B4, except that the coating composition of Example A3 was used instead of the coating composition of Example A1 prepared in Experimental Example 1.

[0125] The solid content of each coating composition in Examples B1 to B6 was adjusted to 50% by appropriately adjusting the water content (dilution or concentration).

[0126] <Measurement and Evaluation> [Viscosity measurement using a BH-type viscometer] Viscosity was measured at 30°C using a BH-type viscometer with a No. 6 rotor at 2 rpm and 20 rpm. From the obtained results, the ratio (Ti value) of viscosity V1 measured at 2 rpm to viscosity V2 measured at 20 rpm was calculated. The results are shown in Table 2.

[0127] [Tensile test] Similar to Experimental Example 1, measurement samples were prepared from the coating compositions related to each example, and tensile tests were performed to measure the breaking strength and elongation at breaking. The results are shown in Table 2.

[0128] [Measurement of storage modulus] Similar to Experimental Example 1, measurement samples were prepared from the coating compositions for each example, and viscoelasticity measurements were performed to determine the storage modulus G' at each temperature. The results are shown in Table 2.

[0129] [RSA-Tg] The peak top temperature of tanδ was determined from the viscoelasticity measurements described above, and this temperature is shown in Table 2 as RSA-Tg.

[0130] [70°C peelability] The coating compositions according to each example were applied to the painted steel sheet using an applicator manufactured by TP Giken Co., Ltd., and dried at 80°C for 3 minutes to form a 100 μm thick film (coating protective coating material) on the painted steel sheet. Next, the painted steel sheet was placed in a constant temperature bath at 70°C, and the peelability of the film when peeling it off the painted steel sheet at this temperature was evaluated at the following two levels. 3 points: The film can be peeled off. 1. The film cannot be peeled off (it stretches and tears).

[0131] [Peelability (23℃)] Using the coating composition for each example, a 100 μm thick film was formed on the painted steel sheet in the same manner as the evaluation of peelability (70°C) described above. The peelability of the film when peeling it off the painted steel sheet was evaluated at the following two levels under conditions of 23°C and 50% RH. 3 points: The film can be peeled off. 1. The film cannot be peeled off (it stretches and tears).

[0132] [Peelability (-30℃)] Using the coating composition described in each example, a 100 μm thick film was formed on the painted steel sheet in the same manner as the evaluation of peelability (70°C) described above. The painted steel sheet was then placed in a -30°C constant temperature bath, and the peelability of the film when peeling it off the painted steel sheet at this temperature was evaluated at the following three levels. 3 points: The film can be peeled off. Two points: The film is stiff and difficult to peel off from the coating, but it is possible to remove the film. 1. The film cannot be peeled off (it stretches and tears).

[0133] [Anti-marking properties] The anti-marking properties were evaluated using the coating compositions for each example in the same manner as in Experimental Example 1. The results are shown in Table 2, using the same three levels as in Experimental Example 1.

[0134] [Table 2]

[0135] As shown in Table 2, the films formed by Examples B1 to B6 all exhibited good peelability from the coating and excellent resistance to leaving marks.

[0136] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Industrial applicability]

[0137] The coating protective coating material provided by the technology described in this specification is suitable as a coating protective coating material that is applied to the coating of an object to be protected which has a coating and serves to protect the coating from damage and deterioration such as scratches and dirt, and is used in a manner that it can be peeled off from the object to be protected after it has finished fulfilling its protective role. The object to be protected may be, for example, a painted metal sheet (for example, painted steel sheet used in housing materials, building materials, ships, railway vehicles, automobiles and other transportation equipment), a synthetic resin sheet with a coating, or molded products thereof. The above-mentioned protective coating material can be preferably used to protect an article to be protected (an article having a coating formed by the above coating treatment, such as a metal plate such as a steel plate or a molded product thereof) which has been coated with paints of various compositions, such as acrylic paints, polyester paints, alkyd paints, melamine paints, urethane paints, acid epoxy crosslinked paints, or composites thereof (e.g., acrylic melamine paints, alkyd melamine paints), by being applied to the coating. [Explanation of symbols]

[0138] 10. Protective coating material for paint film 20 Protected Objects 22 Coating film

Claims

1. A protective coating material formed from a liquid coating composition, The coating composition contains a polymer (A) as a base polymer, which is a polymer of monomer components including an acrylic monomer. The SP value of the polymer (A) is 9.8 (cal / cm³). ３ ) １／２ That's all. The acid value of the polymer (A) is 4.0 mg KOH / g or more and 20 mg KOH / g or less, and The polymer (A) has a glass transition temperature of 0°C or less, calculated based on the composition of the monomer components constituting the polymer (A). A protective coating material having a storage modulus of 0.70 MPa or higher at 70°C.

2. The coating protective material according to claim 1, wherein the acid value of the polymer (A) is 15 mg KOH / g or less.

3. The coating protective material according to claim 1 or 2, wherein the monomer component constituting the polymer (A) includes a nitrogen atom-containing monomer.

4. The coating protective material according to claim 1 or 2, wherein the polymer (A) has a glass transition temperature of -20°C or higher, calculated based on the composition of the monomer components constituting the polymer (A).

5. The coating protective coating material according to claim 1 or 2, wherein the monomer component constituting the polymer (A) comprises an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms at its ester terminus and a carboxyl group-containing monomer.

6. A coating composition used to form a protective coating material according to claim 1 or 2.

7. The coating composition according to claim 6, wherein the composition is in the form of an aqueous emulsion in which the polymer (A) is dispersed in an aqueous solvent.

8. To prepare the coating composition described in claim 6, Applying the coating composition onto the coating of an object to be protected that has a coating, and The coating composition is dried to form a protective coating material that temporarily protects the coating film. A coating protection method including the following.

9. The coating method according to claim 8, wherein the coating composition is applied by a slot die.

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