Resin composition, molded article, optical member, and vehicle member

Abstract

The present invention is a resin composition comprising: a copolymer (A) comprising a repeating unit (A1) derived from a (meth) acrylic acid ester and a repeating unit (A2) derived from a (meth) acrylic acid; a fatty acid metal salt; and a benzotriazole-based ultraviolet absorber.

Description

Technical Field

[0001] This invention relates to a resin composition, a molded article, an optical component, and a vehicle component. Background Technology

[0002] Polymethyl methacrylate (PMMA) is widely used in various fields such as optical materials, automotive components, lighting materials, and building materials due to its excellent transparency and weather resistance. In recent years, the design of PMMA-based optical and automotive components has become increasingly diversified, with a trend towards more complex shapes. Therefore, better moldability is required for PMMA used in these components. However, PMMA has relatively strong adhesion to metals and is brittle. Therefore, especially in injection molding of complex-shaped parts, problems such as cracking and peeling of the molded parts during demolding can easily occur.

[0003] To address this issue, research has been conducted on improving mold release properties by adding lubricants as release agents to polymethyl methacrylate. For example, methods involving the addition of fatty acid metal salts as lubricants are known (Patent Document 1), etc.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 61-73754 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when fatty acid metal salts are added to conventional polymethyl methacrylate (PMMA), it has been confirmed that yellowing occurs in the resulting molded articles due to reactions between the fatty acid metal salts and other additives and their decomposition products contained in the PMMA. Furthermore, it has been confirmed that the poor dispersibility of the fatty acid metal salts relative to PMMA causes turbidity in the resulting molded articles. Moreover, it has been confirmed that this problem becomes more pronounced when UV absorbers such as benzotriazole UV absorbers are included in the resin composition. Due to these problems, it is difficult to obtain molded articles with good color tone and transparency in PMMA with the addition of fatty acid metal salts and subsequently benzotriazole UV absorbers.

[0009] Therefore, the object of the present invention is to provide a resin composition and a molded article thereof, wherein the resin composition suppresses yellowing and turbidity that occur when fatty acid metal salts and benzotriazole ultraviolet absorbers are added, and exhibits excellent hue and transparency.

[0010] Solution for solving the problem

[0011] To solve the above problems, the inventors conducted repeated research and found that by having a repeating unit (A2) from (meth)acrylic acid in the resin composition, yellowing and turbidity caused by fatty acid metal salts can be suppressed, and excellent hue and transparency can be obtained even with the addition of fatty acid metal salts and benzotriazole UV absorbers.

[0012] This invention is based on the following understanding, and its main points are as follows.

[0013] [1] A resin composition comprising: a copolymer (A) comprising repeating units (A1) derived from (meth)acrylate and repeating units (A2) derived from (meth)acrylate; a fatty acid metal salt; and a benzotriazole ultraviolet absorber.

[0014] [2] The resin composition according to [1], wherein, in all repeating units constituting the copolymer (A), 80.0 mol% to 99.0 mol% of repeating units (A1) from (meth)acrylate and 1.0 mol% to 20.0 mol% of repeating units (A2) from (meth)acrylate are included.

[0015] [3] The resin composition according to [1] or [2], wherein the copolymer (A) further comprises a ring-structured unit (A3) in the main chain.

[0016] [4] The resin composition according to [3], wherein the ring structure comprises at least one selected from glutaric anhydride, maleic anhydride, glutarimide, lactone ring and N-substituted maleimide.

[0017] [5] The resin composition according to [4], wherein the ring structure comprises glutaric anhydride.

[0018] [6] The resin composition according to any one of [3] to [5], wherein, among all the repeating units constituting the copolymer (A), it comprises 80.0 mol% to 98.999 mol% of repeating units (A1) from (meth)acrylate, 1.0 mol% to 15.0 mol% of repeating units (A2) from (meth)acrylic acid, and 0.001 mol% to 5.0 mol% of structural units (A3) from the ring structure.

[0019] [7] The resin composition according to any one of [1] to [6], wherein the metal of the fatty acid metal salt is a monovalent to trivalent metal.

[0020] [8] The resin composition according to [7], wherein the metal of the fatty acid metal salt is one or more selected from the group consisting of Li, Na, Mg, Ca, Ba, K and Al.

[0021] [9] The resin composition according to [8], wherein the metal of the fatty acid metal salt is Ca or Mg.

[0022]

[10] The resin composition according to any one of [1] to [9], wherein the fatty acid of the fatty acid metal salt is one or more of the group consisting of saturated fatty acids having 8 to 22 carbon atoms and unsaturated fatty acids having 8 to 22 carbon atoms.

[0023]

[11] The resin composition according to any one of [1] to

[10] , wherein the resin composition further comprises fatty acids.

[0024]

[12] According to the resin composition of

[11] , wherein the fatty acid is one or more selected from the group consisting of saturated fatty acids having 8 to 22 carbon atoms and unsaturated fatty acids having 8 to 22 carbon atoms.

[0025]

[13] The resin composition according to

[12] , wherein the fatty acid is one or more selected from the group consisting of palmitic acid, stearic acid, myristic acid, lauric acid and linalic acid.

[0026]

[14] The resin composition according to

[13] , wherein the fatty acid is palmitic acid.

[0027]

[15] The resin composition according to any one of [1] to

[14] , wherein the content of the fatty acid metal salt is 0.01 to 0.5 parts by weight relative to 100 parts by weight of the copolymer (A).

[0028]

[16] The resin composition according to any one of

[11] to

[15] , wherein the content of the fatty acid contained in the resin composition is 0.01 parts by weight to 1.0 parts by weight relative to 100 parts by weight of the copolymer (A).

[0029]

[17] The resin composition according to any one of [1] to

[16] , wherein the benzotriazole ultraviolet absorber is one or more selected from the group consisting of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, 6-di-tert-pentylphenol and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

[0030]

[18] The resin composition according to

[17] , wherein the benzotriazole ultraviolet absorber is 2-(2H-benzotriazole-2-yl)-4-methylphenol.

[0031]

[19] The resin composition according to any one of [1] to

[18] , wherein the content of the benzotriazole ultraviolet absorber is 0.001 to 0.3 parts by mass relative to 100 parts by mass of the total mass of the resin composition.

[0032]

[20] A resin molded body is formed by molding a resin composition according to any one of [1] to

[19] .

[0033]

[21] An optical component is formed by molding a resin composition according to any one of [1] to

[19] .

[0034]

[22] A vehicle component is formed by molding a resin composition according to any one of [1] to

[19] .

[0035] Invention Effects

[0036] According to the present invention, a resin composition exhibiting excellent hue and transparency and a molded article thereof can be provided, the resin composition comprising a fatty acid metal salt for improving release properties and a benzotriazole ultraviolet absorber for improving weather resistance. Detailed Implementation

[0037] The present invention will now be described in detail, but the present invention is not limited to the following embodiments and can be implemented in various ways within its scope.

[0038] In this specification, "(meth)acrylate" means at least one selected from "acrylate" and "methacrylate", "(meth)acrylic acid" means at least one selected from "acrylic acid" and "methacrylic acid", and "methacrylic resin" means at least one selected from "acrylic resin" and "methacrylic resin".

[0039] In this invention, "monomer" refers to an unpolymerized compound, and "repeating unit" refers to a unit derived from the monomer formed by polymerization of the monomer. The repeating unit can be a unit formed directly through a polymerization reaction, or it can be a unit obtained by processing the polymer to convert a portion of the unit into a different structure.

[0040] In this specification, "the obtained resin molded body" refers to a molded body formed by molding the resin composition of the present invention.

[0041] The present invention will now be described in detail.

[0042] <mechanism>

[0043] According to the present invention, by including a repeating unit (A2) from (meth)acrylic acid in the resin composition, yellowing and turbidity caused by fatty acid metal salts can be suppressed, resulting in excellent hue and transparency. The mechanism can be considered as follows.

[0044] In typical polymethyl methacrylate (PMMA), other additives and their decomposition products are added, as described later. Furthermore, dispersants and their decomposition products are also included in the PMMA manufacturing process. When such PMMA is used in conjunction with fatty acid metal salts, these additives or decomposition products react with the fatty acid metal salts at molding temperatures via acid-base or complexation reactions, sometimes resulting in coloring of the molded body. This coloring is particularly pronounced when PMMA is used with UV absorbers such as benzotriazoles to improve weather resistance, as the fatty acid metal salts induce structural changes in the UV absorbers, leading to strong yellowing. Additionally, due to insufficient compatibility between fatty acid metal salts and PMMA, the fatty acid metal salts aggregate in the resin, causing light scattering and resulting in cloudiness in the molded body. This can be considered as leading to a deterioration in the color tone and transparency of the resin composition and its molded body.

[0045] In contrast, when a copolymer (A) containing repeating units (A2) from (meth)acrylic acid is used in the resin composition, it is speculated that the interaction between the carboxylic acid groups in the repeating units (A2) from (meth)acrylic acid and the fatty acid metal salt inhibits the reaction between the fatty acid metal salt and the contained substances and decomposition products such as benzotriazole UV absorbers and other additives, thus reducing the likelihood of coloring. Furthermore, it is speculated that due to the carboxylic acid groups in the repeating units (A2) from (meth)acrylic acid, the affinity between the polymer chain and the fatty acid metal salt is increased, thereby improving the dispersibility of the fatty acid metal salt and suppressing the turbidity of the resin molded article. It can be considered that through these effects, even with the presence of fatty acid metal salts and benzotriazole UV absorbers, the resulting resin composition and the resin molded article obtained from the resin composition will still exhibit excellent hue and transparency.

[0046] [Resin composition]

[0047] The resin composition of the present invention is a resin composition comprising the copolymer (A) described later, the fatty acid metal salt described later, and the benzotriazole ultraviolet absorber.

[0048] Although the resin composition of the present invention contains fatty acid metal salts and benzotriazole ultraviolet absorbers, it still has excellent hue and transparency.

[0049] <copolymer (a)>

[0050] The copolymer (A) in the resin composition of the present invention (hereinafter sometimes referred to as "copolymer (A) of the present invention") contains repeating units (A1) from (meth)acrylate (hereinafter referred to as "(meth)acrylate unit (A1)" or "unit (A1)") and repeating units (A2) from (meth)acrylic acid (hereinafter referred to as "(meth)acrylic acid unit (A2)" or "unit (A2)") in the main chain.

[0051] The lower limit of the content ratio of (meth)acrylate units (A1) in the copolymer (A) of the present invention is not particularly limited. From the viewpoint of not impairing the inherent properties of methacrylate resins, such as excellent transparency, processability, and mechanical properties of the resulting resin molded article, the content ratio is preferably 80.0 mol%, more preferably 90.0 mol%, and even more preferably 94.0 mol%, relative to the total molar number of repeating units contained in the copolymer (A). On the other hand, the upper limit of the content ratio of (meth)acrylate units (A1) in the copolymer (A) is not particularly limited. From the viewpoint of excellent heat resistance of the resulting resin molded article, the content ratio is preferably 99.999 mol%, more preferably 99.9 mol%, even more preferably 99.5 mol%, particularly preferably 99.0 mol%, and especially preferably 98.999 mol%.

[0052] The above-mentioned preferred upper and lower limits can be combined arbitrarily.

[0053] Examples of repeating units from (meth)acrylate compounds include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, isoborneol methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, norborneol methacrylate, adamantane methacrylate, dicyclopentenyl methacrylate, dicyclopentyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0054] These units (A1) may contain one type or two or more types. From the viewpoint of improving the thermal stability of the resulting resin molded article, methyl methacrylate units are preferred as (meth)acrylate units (A1).

[0055] The (meth)acrylic acid units (A2) contained in the copolymer (A) of the present invention are repeating units derived from acrylic acid and / or methacrylic acid. These units (A2) may contain one type or two or more types.

[0056] In terms of the excellent color and heat resistance of the resulting resin molded article, the methacrylic acid unit is preferred as the (meth)acrylic acid unit.

[0057] From the viewpoint of obtaining a resin molded article with excellent color, heat resistance, and mechanical properties, the lower limit of the content ratio of (meth)acrylic acid units (A2) in the copolymer (A) relative to the total molar number of repeating units contained in the copolymer (A) is preferably 0.5 mol%, more preferably 1.0 mol%, and even more preferably 2.0 mol%. From the viewpoint of not impairing the inherent properties of methacrylic resins such as excellent transparency and weather resistance of the obtained resin molded article, the upper limit of the content ratio of (meth)acrylic acid units (A2) in the copolymer (A) is preferably 20.0 mol%, more preferably 15.0 mol%, even more preferably 7.0 mol%, and particularly preferably 3.5 mol%.

[0058] The above-mentioned preferred upper and lower limits can be combined arbitrarily.

[0059] Furthermore, the copolymer (A) of the present invention may include a ring structure unit (A3) (hereinafter referred to as "ring structure unit (A3)" or "unit (A3)") in the main chain. It is presumed that by including the ring structure unit (A3) in the copolymer (A) of the present invention, the ring structure partially fixes the carbon-carbon bonds of the main chain, hindering the rotational movement of the polymer chain, thereby further improving the heat resistance of the resulting resin molded article.

[0060] Examples of the ring structure include at least one selected from glutaric anhydride, maleic anhydride, glutarimide, lactone ring, and N-substituted maleimide. From the viewpoint of having an excellent hue, glutaric anhydride is preferred.

[0061] The lower limit of the content ratio of the ring structural unit (A3) in the copolymer (A) of the present invention is not particularly limited. From the viewpoint of obtaining a resin molded article with excellent heat resistance, it is preferably 0.001 mol%, more preferably 0.01 mol%, and even more preferably 0.05 mol%, relative to the total molar number of repeating units contained in the copolymer (A). The upper limit of the content ratio of the ring structural unit (A3) in the copolymer (A) is not particularly limited. From the viewpoint of obtaining a resin molded article with excellent heat resistance, it is preferably 10.0 mol%, and from the viewpoint of excellent color suppression, molding appearance and weather resistance, it is more preferably 5.0 mol%, even more preferably 3.0 mol%, and particularly preferably 0.3 mol%.

[0062] The above-mentioned preferred upper and lower limits can be combined arbitrarily.

[0063] The ring structural unit (A3) can be a unit equivalent to the following glutaric anhydride structural unit, which is constructed in a copolymer obtained by copolymerizing (meth)acrylate and (meth)acrylic acid by cyclization reaction of the methoxycarbonyl group from the (meth)acrylate unit (A1) and the carboxyl group from the (meth)acrylic acid unit (A2) adjacent to the (meth)acrylate unit (A1).

[0064] As described in the examples below, the cyclization reaction can be carried out by heating and mixing the copolymer using an extruder or similar equipment.

[0065] It should be noted that, in this specification, the content of each unit in a copolymer (A) containing unit (A1) and unit (A2), or unit (A1), unit (A2) and unit (A3), is set as the percentage of each unit. 1 The value is calculated by H-NMR measurement. Specifically, the method disclosed in International Publication No. 2019 / 013186 can be used.

[0066] The method for manufacturing copolymer (A) is not particularly limited, and examples include bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization. From the viewpoint of superior productivity, bulk polymerization and suspension polymerization are preferred among these polymerization methods. Specifically, the manufacturing methods disclosed in International Publication No. 2017-022393 and International Publication No. 2019 / 013186 can be used.

[0067] The mass-average molecular weight of the copolymer (A) of the present invention is not particularly limited, but is preferably set to 50,000 or more and 150,000 or less, more preferably 70,000 or more and 130,000 or less. If the mass-average molecular weight of the copolymer (A) is 50,000 or more, the resulting resin molded article exhibits excellent mechanical properties. Furthermore, if the mass-average molecular weight of the copolymer (A) is 150,000 or less, the flowability during molding is excellent.

[0068] In order to control the mass-average molecular weight of copolymer (A), it is preferable to adjust the amount of chain transfer agent during the polymerization of the raw material monomer mixture.

[0069] <metal salt of fatty acid>

[0070] From the viewpoint of ease of acquisition, the type of metal of the fatty acid metal salt contained in the resin composition of the present invention is preferably a monovalent to trivalent metal, particularly preferably a monovalent to divalent metal, and especially preferably a monovalent metal.

[0071] Specifically, metals that can be used as fatty acid metal salts include Li, Na, Mg, Ca, Al, Ba, K, and Zn. Among these, Li, Na, Mg, Ca, Al, Ba, and K have high compatibility with the copolymer (A) of the present invention, and the resulting resin molded articles are less prone to turbidity. Therefore, from the viewpoint of improving the release properties of the resulting resin molded articles, Ca or Mg is particularly preferred.

[0072] From the viewpoint of compatibility with the copolymer (A) of the present invention, saturated fatty acids having 8 to 22 carbon atoms and / or unsaturated fatty acids having 8 to 22 carbon atoms are preferred as the fatty acids constituting the fatty acid metal salt used in the present invention. Specific examples of such saturated fatty acids having 8 to 22 carbon atoms and unsaturated fatty acids having 8 to 22 carbon atoms can be listed as fatty acids contained in the resin composition of the present invention described later.

[0073] From the viewpoint of weather resistance, saturated fatty acids with 8 to 22 carbon atoms are preferred as the fatty acid constituting the fatty acid metal salt. From the viewpoint of ease of acquisition, palmitic acid, stearic acid, myristic acid, lauric acid or linalic acid are particularly preferred, and stearic acid is the most preferred.

[0074] From the viewpoint of improving the appearance and release properties of the resulting resin molded articles, calcium stearate and magnesium stearate are preferred as fatty acid metal salts, with magnesium stearate being the most preferred.

[0075] These fatty acid metal salts can be used in combination with one or more types.

[0076] The lower and upper limits of the content of fatty acid metal salt in the resin composition of the present invention are not particularly limited, but are preferably 0.01 parts by mass or more and 0.5 parts by mass or less relative to 100 parts by mass of the copolymer (A).

[0077] When the content of fatty acid metal salt is above the aforementioned lower limit, sufficient improvement in mold release properties can be achieved. More preferably, this lower limit is 0.03 parts by mass or more; even more preferably, 0.04 parts by mass or more; and most preferably, 0.07 parts by mass or more.

[0078] When the content of fatty acid metal salts is below the above-mentioned upper limit, it is less likely to cause contamination of the mold and resin molded body due to excess fatty acid metal salts remaining on the mold surface during demolding. This upper limit is more preferably 0.3 parts by weight or less, further preferably 0.2 parts by weight or less, and most preferably 0.15 parts by weight or less.

[0079] The above-mentioned upper and lower limits can be combined arbitrarily. That is, the content of fatty acid metal salt is preferably 0.01 parts by mass to 0.5 parts by mass, more preferably 0.03 parts by mass to 0.3 parts by mass, further preferably 0.04 parts by mass to 0.2 parts by mass, and most preferably 0.07 parts by mass to 0.15 parts by mass.

[0080] <fatty acid>

[0081] The resin composition of the present invention may further contain fatty acids. It is presumed that by containing fatty acids, not only are carboxyl groups from the repeating unit (A2) of (meth)acrylic acid present, but also carboxyl groups from the fatty acid itself, thereby further interacting with the fatty acid metal salt, inhibiting reactions with the fatty acid metal salt, ultraviolet absorbers, other additives, and decomposition products, thus reducing the likelihood of coloring. Therefore, it is believed that even with the presence of fatty acid metal salts and ultraviolet absorbers, the resulting resin composition and the resin molded article obtained by molding the resin composition will still exhibit superior color tones.

[0082] As for the fatty acids used here, from the viewpoint of maintaining compatibility with the copolymer (A) of the present invention and excellent transparency, saturated fatty acids with 8 to 22 carbon atoms and / or unsaturated fatty acids with 8 to 22 carbon atoms are preferred.

[0083] Examples of saturated fatty acids with 8 to 22 carbon atoms include caprylic acid (8 carbon atoms), nonanoic acid (9 carbon atoms), decanoic acid (10 carbon atoms), lauric acid (12 carbon atoms), myristic acid (14 carbon atoms), pentadecanoic acid (15 carbon atoms), palmitic acid (16 carbon atoms), heptadecanoic acid (17 carbon atoms), stearic acid (18 carbon atoms), arachidic acid (20 carbon atoms), icosanoic acid (21 carbon atoms), and benzalkonium chloride (22 carbon atoms).

[0084] Examples of unsaturated fatty acids with 8 to 22 carbon atoms include myristoleic acid (14 carbon atoms), palmitoleic acid (16 carbon atoms), sapienic acid (16 carbon atoms), oleic acid (18 carbon atoms), transoleic acid (18 carbon atoms), isoleic acid (18 carbon atoms), codoleic acid (20 carbon atoms), eicosenoic acid (20 carbon atoms), erucic acid (22 carbon atoms), linoleic acid (18 carbon atoms), eicosadienoic acid (20 carbon atoms), docosahexaenoic acid (22 carbon atoms), α-linolenic acid (18 carbon atoms), γ-linolenic acid (18 carbon atoms), and pine oil. Acids (18 carbon atoms), α-Tungic acid (18 carbon atoms), β-Tungic acid (18 carbon atoms), Meadic acid (20 carbon atoms), di-gamma-linolenic acid (20 carbon atoms), eicosatrienoic acid (20 carbon atoms), octadecanoic acid (18 carbon atoms), arachidonic acid (20 carbon atoms), eicosatrienoic acid (20 carbon atoms), adrenal acid (22 carbon atoms), bosseopentaenoic acid (18 carbon atoms), eicosapentaenoic acid (20 carbon atoms), osbond acid (22 carbon atoms), herring acid (22 carbon atoms), docosahexaenoic acid (22 carbon atoms), etc.

[0085] These fatty acids can be used in combination with one or more types.

[0086] From the perspective of weather resistance, saturated fatty acids with 8 to 22 carbon atoms are preferred. From the perspective of minimizing mold contamination during molding, palmitic acid, stearic acid, myristic acid, lauric acid, or linalic acid are particularly preferred, with palmitic acid being the most preferred.

[0087] The lower and upper limits of the fatty acid content in the resin composition of the present invention are not particularly limited, but are preferably 0.01 parts by mass or more and 1.0 parts by mass or less relative to 100 parts by mass of the copolymer (A).

[0088] If the content of fatty acids is above the aforementioned lower limit, the improved release properties resulting from the use of fatty acid metal salts can be fully obtained. This lower limit is more preferably 0.03 parts by mass or more, further preferably 0.05 parts by mass or more, particularly preferably 0.1 parts by mass or more, and most preferably 0.15 parts by mass or more.

[0089] If the fatty acid content is below the above-mentioned upper limit, the mold is less likely to be contaminated during molding. This upper limit is more preferably 0.7 parts by weight or less, further preferably 0.5 parts by weight or less, particularly preferably 0.4 parts by weight or less, and most preferably 0.3 parts by weight or less.

[0090] The above-mentioned upper and lower limits can be combined arbitrarily. That is, the content of fatty acids is preferably 0.01 parts by mass to 1.0 parts by mass, more preferably 0.03 parts by mass to 0.7 parts by mass, further preferably 0.05 parts by mass to 0.5 parts by mass, particularly preferably 0.1 parts by mass to 0.4 parts by mass, and most preferably 0.15 parts by mass to 0.3 parts by mass.

[0091] <benzotriazole-based ultraviolet absorber>

[0092] The resin composition of the present invention further comprises a benzotriazole ultraviolet absorber.

[0093] There are no particular restrictions on the use of benzotriazole UV absorbers; any existing and known benzotriazole UV absorbers can be used.

[0094] Examples of benzotriazole-based ultraviolet absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, 6-di-tert-pentylphenol, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol], 2-(2-hydroxy- 3,5-Di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2,2'-methylenebis(4-cumyl-6-(2H-benzotriazole-2-yl)phenol, 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(2-hydroxyethyl)phenol], 2-[2-hydroxy-3-(4,5,6,7-tetrahydro-1,3-dioxo-1H-isoindol-2-ylmethyl)-5-methylphenyl]-2H-benzotriazole, etc.

[0095] Among these, from the viewpoint of compatibility with methacrylic resins, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, 6-di-tert-pentylphenol, and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole are preferred, with 2-(2H-benzotriazole-2-yl)-4-methylphenol being particularly preferred.

[0096] These benzotriazole UV absorbers can be used in combination with one or more types.

[0097] These benzotriazole UV absorbers can be commercially available, such as the Tinuvin (registered trademark) series manufactured by BASF Japan.

[0098] The lower and upper limits of the content of benzotriazole ultraviolet absorber in the resin composition of the present invention are not particularly limited, but are preferably 0.001 parts by mass or more and 0.3 parts by mass or less relative to 100 parts by mass of the total mass of the resin composition of the present invention.

[0099] If the content of benzotriazole UV absorber is above the lower limit mentioned above, the improvement in weather resistance brought about by the presence of benzotriazole UV absorber can be fully obtained.

[0100] The content of benzotriazole ultraviolet absorber is more preferably 0.002 parts by mass or more, further preferably 0.003 parts by mass or more, particularly preferably 0.005 parts by mass or more, and most preferably 0.009 parts by mass or more.

[0101] If the content of benzotriazole UV absorbers is below the above-mentioned upper limit, the yellowing of the resin molded body caused by the presence of benzotriazole UV absorbers can be reduced. More preferably, the content of benzotriazole UV absorbers is 0.2 parts by weight or less, further preferably 0.1 parts by weight or less, particularly preferably 0.08 parts by weight or less, and most preferably 0.06 parts by weight or less.

[0102] The above-mentioned upper and lower limits can be combined arbitrarily. That is, the content of benzotriazole ultraviolet absorber in the resin composition of the present invention is preferably 0.001 parts by weight to 0.3 parts by weight, more preferably 0.002 parts by weight to 0.2 parts by weight, further preferably 0.003 parts by weight to 0.1 parts by weight, particularly preferably 0.005 parts by weight to 0.08 parts by weight, and most preferably 0.009 parts by weight to 0.06 parts by weight.

[0103] <other additives>

[0104] In addition to the copolymer (A), fatty acid metal salt, fatty acid, and benzotriazole ultraviolet absorber, the resin composition of the present invention may also contain one or more of various additives commonly added to resin compositions, within a range that does not impair the effects of the present invention.

[0105] Examples of such additives include light diffusing agents, antioxidants, colorants, pigments, dyes, heat stabilizers, reinforcing agents, fillers, flame retardants, foaming agents, lubricants, plasticizers, antistatic agents, light stabilizers, impact modifiers, flow modifiers, release agents, processing elasticity imparting agents, and ultraviolet absorbers other than benzotriazole ultraviolet absorbers.

[0106] <Method for producing resin composition>

[0107] As a method for manufacturing the resin composition of the present invention, methods (1) or (2) described below can be cited as examples.

[0108] (1) A method of mixing the copolymer (A) of the present invention, the fatty acid metal salt and the benzotriazole ultraviolet absorber, as well as the fatty acid and other additives used as needed, by heating, melting and mixing them in a single screw extruder or a twin screw extruder.

[0109] (2) A method of mixing fatty acid metal salts and benzotriazole ultraviolet absorbers, as well as fatty acids and other additives as needed, into the monomers constituting the copolymer (A) of the present invention and then polymerizing them.

[0110] [Resin molded body]

[0111] The resin molded body of the present invention is formed by molding the resin composition of the present invention.

[0112] The resin molded articles of the present invention are not particularly limited as long as they are formed by known molding methods, such as compression molding, injection molding, gas-assisted injection molding, weld molding, extrusion molding, blow molding, film molding, hollow molding, multilayer molding, melt spinning, etc. From the viewpoint of obtaining the improved release properties and flowability brought about by fatty acid metal salts, the resin composition of the present invention is suitable as a resin composition for injection molding.

[0113] Specific examples of resin molded articles of the present invention include vehicle parts such as taillight covers, headlight covers, inner lenses, dashboards, pillar trims, front grilles, and car logos; optical parts such as lenses and light guides; building parts; parts for residential equipment such as vanity tables, bathtubs, and toilets; containers for cosmetics; and medical parts such as cuvettes.

[0114] Among these, the resin molded articles of the present invention are particularly suitable for use in vehicle parts, optical parts, containers, and medical parts due to their excellent appearance, weather resistance, transparency, and chemical resistance, especially as vehicle parts and optical parts.

[0115] Examples

[0116] The present invention will be described in more detail below with reference to specific embodiments.

[0117] [Raw materials used]

[0118] The abbreviations of the compounds used in the following examples and comparative examples are as follows.

[0119] MMA: Methyl methacrylate (trade name: Acryester (registered trademark) M, manufactured by Mitsubishi Chemical Corporation)

[0120] MA: Methyl acrylate (manufactured by Mitsubishi Chemical Corporation)

[0121] MAA: Methacrylic acid

[0122] Polymerization initiator (1): 2,2'-azobis(2-methylpropanediamine) dihydrochloride

[0123] Polymerization initiator (2): 2,2'-azobis-2-methylbutyronitrile (trade name: V-59, manufactured by Wako Pure Chemical Industries, Ltd.)

[0124] Chain transfer agent (1): n-Octaylthiol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0125] Copolymer (1): Methacrylic resin manufactured in Example 1

[0126] Copolymer (2): Methacrylic resin manufactured in Example 2

[0127] Fatty acid metal salts (1): Lithium stearate (trade name: LI-ST, manufactured by Nitto Kasei Corporation) (listed as "Li stearate" in Table 1)

[0128] Fatty acid metal salts (2): Sodium stearate (trade name: NA-ST, manufactured by Nitto Kasei Corporation) (listed as "Na stearate" in Table 1)

[0129] Fatty acid metal salts (3): Magnesium stearate (trade name: Mg-St, manufactured by Nitto Kasei Corporation) (listed as "Mg stearate" in Table 1)

[0130] Fatty acid metal salts (4): Calcium stearate (trade name: Ca-St, manufactured by Nitto Kasei Corporation) (listed as "Ca stearate" in Table 1)

[0131] Benzotriazole UV absorber: 2-(2H-benzotriazole-2-yl)-4-methylphenol (Tinuvin (registered trademark)-P, manufactured by BASF Japan)

[0132] [Method of evaluation]

[0133] <Content rate of each unit in methacrylic resin>

[0134] The methacrylic acid polymer obtained in the manufacturing example and deuterated dimethyl sulfoxide were fed into a 20 mL Schlenk tube equipped with a stir bar. While stirring, the mixture was heated to 80°C to dissolve the methacrylic acid resin. Then, the mixture was cooled to 23°C, and benzylamine was fed into the Schlenk tube. While stirring, the mixture was heated to 80°C. After reacting for 1 hour, the reaction solution was removed, and nuclear magnetic resonance (NMR) was performed using a Varian Magnetic Resonance Apparatus (270 MHz) at a measurement temperature of 80°C and a cumulative measurement of 32 times. 1 H-NMR determination.

[0135] Based on the results 1 Based on the H-NMR measurements, the content of unit (A3) in methacrylic acid resins was calculated using the ratio of the integral value of benzyl protons from the singlet peak of unreacted benzylamine around 3.7 ppm to the integral value of benzyl protons from the singlet peak of glutaric acid benzylamide around 4.2 ppm. Furthermore, the content of units (A1) and (A2) in methacrylic acid resins was calculated by taking the ratios of the integral value of protons from unit (A1) from the singlet peak around 3.5 ppm, and the integral values ​​of protons from units (A1) and (A2) from the singlet peak around 0.5 ppm to the integral value of benzyl protons from the singlet peak of unreacted benzylamine around 3.7 ppm, respectively.

[0136] <Color tone of resin molded body after injection molding>

[0137] (1) Production of test piece

[0138] After drying the particulate methacrylic resin compositions obtained in the examples and comparative examples with hot air at 80°C for about 16 hours, they were injection molded under the following conditions to produce test pieces for color evaluation.

[0139] • Injection Molding Machine: Model Name: EC75-SXII, Manufactured by Shibaura Machinery Co., Ltd.

[0140] • Mold: Plate-shaped molded body, 200mm×30mm×4mm

[0141] • Barrel temperature: 250℃

[0142] • Mold temperature: 60℃

[0143] (2) Color tone evaluation

[0144] For resin molded specimens, a Hitachi High-Tech Spectrophotometer "U-4100" was used to measure the yellowness index (YI) over a 200mm optical path length using the transmission method according to JIS K7105, based on the C-source transmission method. This value was used as an indicator for evaluating yellowness. Additionally, the transmittance at a wavelength of 700nm was calculated from the transmittance obtained during the YI measurement and used as an indicator for evaluating turbidity.

[0145] The test was performed on three test pieces, and the average value was calculated. The results were evaluated according to the following criteria. The results are shown in Table 1.

[0146] 〇: YI value less than 26 and transmittance exceeding 80% at a wavelength of 700nm.

[0147] ×: YI value above 26 or transmittance below 80% at a wavelength of 700nm

[0148] [Production example 1]

[0149] 900 parts by weight of deionized water, 60 parts by weight of sodium 2-ethanesulfonate methacrylate, 10 parts by weight of potassium methacrylate and 12 parts by weight of MMA were added to a reaction vessel equipped with a reflux cooler and internal nitrogen purging. The mixture was stirred and heated until the liquid temperature inside the reaction vessel reached 50°C.

[0150] Then, 0.08 parts by mass of polymerization initiator (1) were added, and while stirring, the temperature in the reaction vessel was raised to 60°C. Then, MMA was continuously added dropwise over 75 minutes at a rate of 0.24 parts by mass / minute using a drop pump. Then, polymerization was carried out for another 6 hours to obtain a dispersant (10% by mass of solids).

[0151] 2000 parts by mass of deionized water and 4.2 parts by mass of sodium sulfate were added to a reaction vessel equipped with a nitrogen inlet pipe and a reflux cooler, and stirred at 320 rpm for 15 minutes. Then, a mixed solution of 1351.6 parts by mass of MMA, 36.3 parts by mass of MAA, 12.1 parts by mass of MA, 2.8 parts by mass of polymerization initiator (2), and 4.2 parts by mass of chain transfer agent (1) was added to the reaction vessel and stirred for 5 minutes. Next, 6.72 parts by mass of the dispersant (10% by mass of solids) was added to the reaction vessel and stirred to disperse the monomer composition in the water. Then, the reaction vessel was purged with nitrogen.

[0152] Next, the temperature inside the reaction vessel was raised to 75°C, and the temperature was continuously measured and maintained at 75°C until the exothermic polymerization peak was observed. After the exothermic polymerization peak was observed, the temperature inside the reaction vessel was raised to 90°C and maintained for 60 minutes to carry out polymerization. Then, the mixture inside the reaction vessel was filtered, the filter was washed with deionized water, and dried at 80°C for 16 hours to obtain bead-like copolymers, which were used as polymer precursors for methacrylic resins (1).

[0153] The composition of the polymer precursor (1) was analyzed according to the above-mentioned method for determining the content of each unit in methacrylic resin. The results showed that the repeating unit from methyl methacrylate (hereinafter referred to as "MMA unit") was 96.0 mol%, the repeating unit from methacrylic acid (hereinafter referred to as "MAA unit") was 3.0 mol%, and the repeating unit from methyl acrylate (hereinafter referred to as "MA unit") was 1.0 mol.

[0154] The polymer precursor (1) was fed into a twin-screw extruder (model name "TEM18SS", manufactured by Shibaura Machinery Co., Ltd.) and mixed at 250°C to obtain granular methacrylic resin, which was used as copolymer (1).

[0155] The resulting copolymer (1) has the following composition: 97.2 mol% methyl methacrylate units, 2.7 mol% methyl methacrylate units, and 0.1 mol% glutaric anhydride units. It should be noted that the methyl methacrylate units refer to repeating units that combine MMA units and MA units.

[0156] In this manufacturing example 1, glutaric anhydride units were generated by cyclization of the methoxycarbonyl groups of the MMA and MA units with the carboxyl groups of the MAA unit through heated compounding in a twin-screw extruder.

[0157] [Production example 2]

[0158] Except for not using MAA as a monomer, the same operation as in Manufacturing Example 1 was performed to obtain a copolymer (2) without MAA units. The composition of the obtained copolymer (1) was 100 mol% (meth)acrylate units.

[0159] [Example 1]

[0160] 100 parts by weight of copolymer (1), 0.01 parts by weight of lithium stearate as a fatty acid metal salt, and 0.05 parts by weight of Tinuvin-P as a UV absorber were fed into a twin-screw extruder (model name "TEM18SS", manufactured by Shibaura Machinery Co., Ltd.), and melt-blended at a barrel temperature of 250°C to obtain a granular resin composition. The evaluation results of the obtained resin composition are shown in Table 1.

[0161] [Examples 2 to 8]

[0162] Except for changing the type and amount of fatty acid metal salts added, the procedure was the same as in Example 1 to obtain a particulate resin composition. The evaluation results of the obtained resin composition are shown in Table 1.

[0163] [Comparative examples 1 to 7]

[0164] Except that copolymer (2) was used instead of copolymer (1), the same procedures as in Examples 1 to 8 were followed to obtain particulate resin compositions. The evaluation results of the obtained resin compositions are shown in Table 1.

[0165] [Reference example 1]

[0166] Except for the absence of fatty acid metal salts, the procedure was performed in the same manner as in Example 1 to obtain a particulate resin composition. The evaluation results of the obtained resin compositions are shown in Table 1.

[0167] [Reference example 2]

[0168] Except for the absence of fatty acid metal salts, the procedure was performed in the same manner as in Comparative Example 1 to obtain a particulate resin composition. The evaluation results of the obtained resin compositions are shown in Table 1.

[0169]

[0170] As can be clearly seen from Table 1, the resin composition of the present invention, which contains a fatty acid metal salt and a benzotriazole UV absorber in a copolymer (1) containing a (meth)acrylic acid unit (A2) as shown in Examples 1 to 8, can produce a resin molded body that suppresses yellowing and turbidity caused by the fatty acid metal salt and has excellent hue and transparency.

[0171] It can be seen that, in contrast, in Comparative Examples 1 to 7, where copolymer (2) without (meth)acrylic acid unit (A2) was used instead of copolymer (1), yellowing and turbidity caused by fatty acid metal salts occurred, which impaired the color and transparency of the resin molded body.

[0172] It should be noted that, as can be seen from Reference Examples 1 and 2, when copolymers (1) and (2) do not contain fatty acid metal salts, they have excellent color and transparency. The yellowing and turbidity are caused by fatty acid metal salts.

[0173] As can be seen from the above, according to the present invention, by making the copolymer (A) in the resin composition have (meth)acrylic acid units (A2), yellowing and turbidity caused by fatty acid metal salts can be suppressed, and excellent hue and transparency can still be obtained even when fatty acid metal salts and benzotriazole UV absorbers are added.

[0174] The invention has been described in detail using specific methods, but it will be clear to those skilled in the art that various modifications can be made without departing from the intent and scope of the invention.

[0175] This application is based on Japanese Patent Application 2023-136439, filed on August 24, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A resin composition comprising: a copolymer (A) comprising repeating units (A1) derived from (meth)acrylate and repeating units (A2) derived from (meth)acrylate; a fatty acid metal salt; and a benzotriazole ultraviolet absorber.

2. The resin composition according to claim 1, wherein, Of all the repeating units constituting the copolymer (A), 80.0 mol% to 99.0 mol% of repeating units (A1) derived from (meth)acrylate and 1.0 mol% to 20.0 mol% of repeating units (A2) derived from (meth)acrylate are included.

3. The resin composition according to claim 1, wherein, The copolymer (A) also contains ring-structured units (A3) in the main chain.

4. The resin composition according to claim 3, wherein, The ring structure comprises at least one selected from glutaric anhydride, maleic anhydride, glutarimide, lactone ring, and N-substituted maleimide.

5. The resin composition according to claim 4, wherein, The ring structure contains glutaric anhydride.

6. The resin composition according to claim 3, wherein, Of all the repeating units constituting the copolymer (A), there are 80.0 mol% to 98.999 mol% repeating units (A1) derived from (meth)acrylate, 1.0 mol% to 15.0 mol% repeating units (A2) derived from (meth)acrylic acid, and 0.001 mol% to 5.0 mol% structural units (A3) derived from the ring structure.

7. The resin composition according to claim 1, wherein, The metal in the fatty acid metal salt is a monovalent to trivalent metal.

8. The resin composition according to claim 7, wherein, The metal in the fatty acid metal salt is one or more selected from the group consisting of Li, Na, Mg, Ca, Ba, K and Al.

9. The resin composition according to claim 8, wherein, The metal of the fatty acid metal salt is Ca or Mg.

10. The resin composition according to claim 1, wherein, The fatty acid metal salt is composed of one or more fatty acids selected from the group consisting of saturated fatty acids with 8 to 22 carbon atoms and unsaturated fatty acids with 8 to 22 carbon atoms.

11. The resin composition according to claim 1, wherein, The resin composition also contains fatty acids.

12. The resin composition according to claim 11, wherein, The fatty acid is one or more selected from the group consisting of saturated fatty acids with 8 to 22 carbon atoms and unsaturated fatty acids with 8 to 22 carbon atoms.

13. The resin composition according to claim 12, wherein, The fatty acid is selected from one or more of the group consisting of palmitic acid, stearic acid, myristic acid, lauric acid and linalic acid.

14. The resin composition according to claim 13, wherein, The fatty acid is palmitic acid.

15. The resin composition according to claim 1, wherein, The content of the fatty acid metal salt is 0.01 to 0.5 parts by mass relative to 100 parts by mass of the copolymer (A).

16. The resin composition according to claim 11, wherein, The content of the fatty acid contained in the resin composition is 0.01 to 1.0 parts by weight relative to 100 parts by weight of the copolymer (A).

17. The resin composition according to claim 1, wherein, The benzotriazole ultraviolet absorber is one or more selected from the group consisting of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-4-methylphenol, 6-di-tert-pentylphenol, and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

18. The resin composition according to claim 17, wherein, The benzotriazole ultraviolet absorber is 2-(2H-benzotriazole-2-yl)-4-methylphenol.

19. The resin composition according to claim 1, wherein, The content of the benzotriazole ultraviolet absorber is 0.001 to 0.3 parts by mass relative to 100 parts by mass of the total mass of the resin composition.

20. A resin molded body, formed by molding a resin composition according to any one of claims 1 to 19.

21. An optical component is formed from a resin composition according to any one of claims 1 to 19.

22. A vehicle component is formed from a resin composition according to any one of claims 1 to 19.

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