(Met)acrylic resin composition and a molded article using the same, and a method for manufacturing a (met)acrylic resin composition

Abstract

The present invention aims to provide a (meth)acrylic resin composition capable of reducing roll contamination and further suppressing the occurrence of silver streaks, while also having excellent stability. The present invention also aims to provide a molded article using the (meth)acrylic resin composition and a method for manufacturing the (meth)acrylic resin composition. A (meth)acrylic resin composition comprising a (meth)acrylic polymer having a ring structure in its main chain that is at least one of a lactone ring structure and a glutaric anhydride structure, wherein the content of phosphorus atoms in the (meth)acrylic resin composition is 1.0 ppm or more and 50 ppm or less, and the content of a compound represented by the following formula (I) in the (meth)acrylic resin composition is 95 ppm or less. [In Formula (I), R1 represents an aliphatic hydrocarbon group having 13 or more carbon atoms, or an aromatic hydrocarbon group having 6 or more carbon atoms.]

Description

Technology Field

[0001] The present invention relates to a (meth)acrylic resin composition, a molded article using the same, and a method for manufacturing a (meth)acrylic resin composition. Background Technology

[0002] (Meth)acrylic resins are suitable for use in optical components because they offer an excellent balance of various properties such as optical properties, mechanical strength, moldability, and surface hardness. However, (meth)acrylic resins generally have a low glass transition temperature (Tg) and poor heat resistance. Therefore, to improve the heat resistance of (meth)acrylic resins, (meth)acrylic resins are known to have a ring structure, such as a lactone ring structure, introduced into the main chain. As a method for manufacturing (meth)acrylic resins having a lactone ring structure, a method has been proposed in which, for example, in a polymer having hydroxyl groups and ester groups in the molecular chain, an organic phosphorus compound is used as a catalyst to form a lactone ring structure in the molecular chain by condensing the polymer upon heating (Patent Documents 1 and 2). In Patent Document 1, the catalyst specifically used is methyl phosphate or phenylaphosphonic acid. In Patent Document 2, the catalyst specifically used is stearyl phosphate. Prior art literature

[0003] Japanese Patent Publication No. 2001-151814 Japanese Patent Publication No. 2017-145387 The problem to be solved

[0004] The methyl phosphate specifically used in Patent Document 1 had low cyclization efficiency. Therefore, in order to form a desired ratio of ring structure in the polymer, it was necessary to use a large amount of catalyst. If a large amount of catalyst was used, there was a concern that a large amount of components derived from the catalyst (compounds containing phosphorus atoms) would remain in the resulting (meth)acrylic resin composition. Since phosphorus atoms are corrosive, there was a concern regarding the stability of the (meth)acrylic resin. On the other hand, if the amount of catalyst was reduced, there was a concern that silver streaks would occur in the (meth)acrylic resin composition. Furthermore, when stearyl phosphate specifically used in Patent Document 2 was used as a cyclization catalyst, there was a problem that the surface of the roll used for film manufacturing was prone to contamination when the resin was made into a film. If the surface of the roll was contaminated, there was a concern that the appearance of the resulting film would be damaged or production efficiency would decrease.

[0005] Regarding this issue, Patent Document 2 investigated suppressing contamination of the roll surface by controlling the content of phosphorus elements or hindered phenol compounds with a molecular weight of less than 300 in the resin composition, that is, by controlling the amount of phosphorus-based antioxidants having hindered phenol groups (by not adding them in excess). However, it was thought that there is a limit to suppressing contamination of the roll surface because even if the amount of phosphorus-based antioxidants having hindered phenol groups is suppressed, sources of contamination on the roll surface still exist, and stearyl phosphate is used as a specific example.

[0006] The present invention was made in light of the above circumstances, and its purpose is to provide a (meth)acrylic resin composition that can reduce roll contamination, further suppress the occurrence of silver streaks, and has excellent stability. In addition, the present invention also aims to provide a molded article using the (meth)acrylic resin composition and a method for manufacturing the (meth)acrylic resin composition. means of solving the problem

[0007] The inventors, as a result of careful investigation to solve the above problem, discovered that the adhesion of stearyl phosphate or its derived components (such as stearyl alcohol) used as a cyclization catalyst to the roll surface was a cause of contamination, and that if an ester obtained from phosphoric acid, phosphoric acid, hypophosphoric acid, etc., and lower or intermediate aliphatic alcohols (especially aliphatic alcohols with 3 to 12 carbon atoms) is used as a cyclization catalyst, the catalyst is stabilized during the cyclization process, allowing for a reduction in the amount of catalyst used and suppressing the occurrence of silver streaks, while also obtaining a (meth)acrylic resin composition with excellent stability. Furthermore, if an ester obtained from phosphoric acid, phosphoric acid, hypophosphoric acid, etc., and lower or intermediate aliphatic alcohols is used as a cyclization catalyst, the catalyst is easily volatilized and removed during the degassing process, and furthermore, since lower or intermediate aliphatic alcohols generated by decomposition are also removed during the degassing process, roll contamination caused by the cyclization catalyst is reduced, and thus the present invention was completed.

[0008] That is, the present invention is defined by the following constituent requirements.

[0009] [1] A (meth)acrylic resin composition comprising a (meth)acrylic polymer having a ring structure in the main chain that is at least one of the lactone ring structure and the glutaric anhydride structure,

[0010] The content of phosphorus atoms in the (meth)acrylic resin composition is 1.0 ppm or more and 50 ppm or less, and

[0011] A (meth)acrylic resin composition characterized by having a content of a compound represented by the following formula (I) in the (meth)acrylic resin composition of 95 ppm or less.

[0012]

[0013] [Equation (I), R 1 represents an aliphatic hydrocarbon group with 13 or more carbon atoms, or an aromatic hydrocarbon group with 6 or more carbon atoms.

[0014] [2] A (meth)acrylic resin composition described in [1] having a content of 95 ppm or less of the compound represented by the following formula (II) in the (meth)acrylic resin composition.

[0015]

[0016] [In Equation (II), R 2 represents an aliphatic hydrocarbon group with 3 to 12 carbon atoms.

[0017] [3] A (meth)acrylic resin composition described in [1] or [2] having a ring structure (meth)acrylic polymer, wherein the content of ring structure units is 5 mass% or more and 70 mass% or less.

[0018] [4] A (meth)acrylic resin composition described in any one of [1] to [3] having a (meth)acrylic polymer having a ring structure in the (meth)acrylic resin composition, with a content of 50 mass% or more.

[0019] [5] A (meth)acrylic resin composition described in any of [1] to [4] having a glass transition temperature of 120°C or higher.

[0020] [6] A (meth)acrylic resin composition as described in any of [1] to [5] that does not contain hindered phenol compounds.

[0021] [7] A (meth)acrylic resin composition as described in any of [1] to [6] that does not contain an organic phosphorus compound having a hindered phenolic group.

[0022] [8] A molded body comprising a (meth)acrylic resin composition as described in any of [1] to [7].

[0023] [9] A molded body described in [8] of a sheet, film or lens.

[0024]

[10] A method for preparing a (meth)acrylic resin composition comprising a cyclization process in which at least one of the following (i) and (ii) cyclization reactions is performed on a (meth)acrylic polymer to form a ring structure on the main chain of the (meth)acrylic polymer, wherein the (meth)acrylic polymer is cyclized, the method comprises:

[0025] (i) Cyclic reaction forming a lactone ring structure between a hydroxyl group and an ester or carboxyl group

[0026] (ii) Cyclic reaction between a carboxyl group and an ester group or another carboxyl group to form a glutaric anhydride structure

[0027] In the above cyclization reaction, phosphoric acid C 3-12 Alkyl ester, C phosphoric acid 3-12 Alkyl esters and C hypophosphorus 3-12 A method for preparing a (meth)acrylic resin composition characterized by using at least one selected from the group consisting of alkyl esters as a catalyst.

[0028]

[11] The catalyst used in the above cyclization reaction is C phosphoric acid. 3-7 Alkyl ester, C phosphoric acid 3-7 Alkyl esters and C hypophosphorus 3-7 A method for preparing a (meth)acrylic resin composition described in

[10] , which is at least one selected from the group consisting of alkyl esters.

[0029]

[12] A method for preparing a (meth)acrylic resin composition as described in

[10] or

[11] , wherein the catalyst used in the above cyclization reaction is at least one selected from the group consisting of butyl phosphate, butyl phosphite and butyl hypophosphite.

[0030]

[13] A method for preparing a (meth)acrylic resin composition as described in any of

[10] to

[12] , wherein the amount of the catalyst used is 1000 ppm or less relative to the total amount of monomer components constituting the (meth)acrylic polymer.

[0031]

[14] A method for manufacturing a (meth)acrylic resin composition as described in any of

[10] to

[13] , wherein the decomposition temperature of the catalyst is 160°C or higher.

[0032]

[15] A method for preparing a (meth)acrylic resin composition as described in any one of

[10] to

[14] , further comprising a polymerization process of polymerizing (meth)acrylic monomers to form the (meth)acrylic polymer.

[0033]

[16] A method for preparing a (meth)acrylic resin composition as described in

[15] , wherein the total content ratio of the constituent units derived from the (meth)acrylic monomer in all constituent units of the (meth)acrylic polymer is 50 mass% or more.

[0034]

[17] A method for preparing a (meth)acrylic resin composition as described in

[15] or

[16] , wherein the (meth)acrylic monomer is α-(1-hydroxyalkyl)alkyl acrylate, and the total content ratio of the constituent units derived from α-(1-hydroxyalkyl)alkyl acrylate in the (meth)acrylic polymer is 5 mass% or more.

[0035]

[18] An additive is added in one or more processes selected from the above polymerization process, the above cyclization process and the process after the above cyclization process, and

[0036] A method for preparing a (meth)acrylic resin composition as described in any of

[15] to

[17] , wherein the above additive does not include hindered phenol compounds and organic phosphorus compounds having hindered phenol groups. Effects of the invention

[0037] According to the present invention, a (meth)acrylic resin composition with excellent stability and reduced roll contamination can be provided, furthermore, while suppressing the occurrence of silver streaks. Specific details for implementing the invention

[0038] 1. (Met)acrylic resin composition

[0039] The (meth)acrylic resin composition of the present invention comprises a (meth)acrylic polymer having a ring structure in the main chain that is at least one of a lactone ring structure and a glutaric anhydride structure, and is characterized in that the content of phosphorus atoms in the composition is 1.0 ppm or more and 50 ppm or less, and the content of a compound represented by the following formula (I) in the composition is 95 ppm or less. The (meth)acrylic resin composition of the present invention, having the above compositional requirements, can reduce roll contamination and further suppress the occurrence of silver streaks, while also having excellent stability.

[0040]

[0041] [Equation (I), R 1 represents an aliphatic hydrocarbon group with 13 or more carbon atoms, or an aromatic hydrocarbon group with 6 or more carbon atoms.

[0042] In the present invention, unless specifically stated otherwise, the notation “ppm” refers to a value obtained by mass conversion (for example, 10,000 ppm corresponds to 1 mass%). Also, “C 3-12 The statement 」 means “3 or more carbon atoms or less than or equal to 12”.

[0043] 1.1 (Met)acrylic polymers

[0044] A (meth)acrylic polymer refers to a polymer having (meth)acrylic acid, (meth)acrylic acid esters, or derivatives thereof (hereinafter collectively referred to as (meth)acrylic monomers) as monomer units (i.e., constituent units). Additionally, "(meth)acrylic acid" is a term that includes both acrylic acid and methacrylic acid.

[0045] As (meth)acrylic acid esters, for example, alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate (preferably C methacrylate) 2-20 Examples include aralkyls); esters of (meth)acrylic acids, such as cyclohexyl (meth)acrylate and dicyclofentanyl (meth)acrylate, with hydroxycyclic saturated hydrocarbons (preferably hydroxycyclic saturated hydrocarbons having 5 to 20 carbon atoms). As for the (meth)acrylic acid ester, it is preferably a methacrylic acid ester, more preferably an alkyl methacrylate, and even more preferably C methacrylate. 1-10 It is alkyl, and more preferably methacrylic acid C 1-7 It is alkyl, and even more preferably methacrylic acid C 1-4 It is alkyl, and particularly preferably methacrylic acid C 1-2 It is an alkyl.

[0046] Examples of (meth)acrylic acid ester derivatives include hydroxyl group-introducing derivatives, such as (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2,3,4,5,6-pentahydroxyhexyl, (meth)acrylic acid 2,3,4,5-tetrahydroxypentyl, etc. (meth)acrylic acid hydroxyalkyl; α-(1-hydroxyalkyl)acrylic acid alkyl, etc.

[0047] As for (meth)acrylate hydroxyalkyl, (meth)acrylate hydroxy C 1-20 Alkyl is preferred, and (meth)acrylic acid hydroxy C 1-15 Alkyl is more preferable, and (meth)acrylic acid hydroxy C 1-10 Alkyl is more preferable, and (meth)acrylic acid hydroxy C 1-5 Alkyl is more preferable.

[0048] As for α-(1-hydroxyalkyl)alkyl acrylate, α-(1-hydroxy C 1-20Alkyl)acrylic acid C 1-20 Alkyl is preferred, and α-(1-hydroxy C 1-20 Alkyl)acrylic acid C 1-20 Among the alkyls, α-(hydroxymethyl)acrylate C, such as α-(hydroxymethyl)acrylate methyl, α-(hydroxymethyl)acrylate ethyl, α-(hydroxymethyl)acrylate isopropyl, α-(hydroxymethyl)acrylate n-butyl, and α-(hydroxymethyl)acrylate t-butyl, are included. 1-20 Alkyl; α-(1-hydroxy C such as α-(1-hydroxyethyl)methyl acrylate 2-20 Alkyl)acrylic acid C 1-20 It includes alkyls, etc.

[0049] In addition, as (meth)acrylic acid ester derivatives, β-C such as methyl crotonicate 1-10 Alkyl acrylic acid C 1-10 Alkyl; halogen-introduced derivatives such as (meth)acrylate chloromethyl, (meth)acrylate 2-chloroethyl, etc.; ether-introduced derivatives such as (meth)acrylate dicyclofentanyloxyethyl, etc. are also included.

[0050] As a (meth)acrylic acid ester derivative, it is preferably a hydroxyl group-introducing derivative, more preferably an α-(1-hydroxyalkyl)acrylate alkyl, and even more preferably an α-(1-hydroxyC 1-20 Alkyl)acrylic acid C 1-20 It is alkyl, and more preferably α-(hydroxymethyl)acrylic acid C 1-20 It is an alkyl.

[0051] As (meth)acrylic acid derivatives, compounds obtained by hydrolyzing the ester bonds of the above methacrylic acid ester derivatives, such as crotonic acid, α-(hydroxymethyl)acrylic acid, 2-(1-hydroxyethyl)acrylic acid, and α-hydroxyalkylacrylic acids, are included.

[0052] The (meth)acrylic monomer having a (meth)acrylic polymer as a monomer unit may be a single one or a combination of two or more types. It is preferable to include (meth)acrylic acid or (meth)acrylic acid ester as an essential unit among the (meth)acrylic monomers, and it is more preferable to include (meth)acrylic acid ester (particularly methacrylic acid ester) as an essential unit. The content ratio of the essential unit is, for example, 30 mass% or more, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 65 mass% or more, even more preferably 70 mass% or more, particularly preferably 75 mass% or more in the (meth)acrylic polymer, and for example, 100 mass% or less, preferably 95 mass% or less, more preferably 90 mass% or less, and even more preferably 85 mass% or less. In addition, if the (meth)acrylic polymer has units derived from (meth)acrylic monomers that have become different units due to the cyclization reaction, etc. described below, the units derived from the (meth)acrylic monomers that have become different units shall not be included in the ratio of (meth)acrylic monomer units in the above content ratio.

[0053] The (meth)acrylic polymer may have constituent units introduced by copolymerizing the above (meth)acrylic monomer with another monomer. Such other monomers are not particularly limited as long as they are compounds having polymerizable double bonds, and include, for example, styrene-based monomers such as styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene; nitrogen-containing heterocyclic vinyl compounds such as N-vinylpyrrolidone, N-vinylcarbazole; vinylnitrites such as acrylonitrile, methacrylonitrile; vinyl alcohols such as metallyl alcohol, allyl alcohol; olefins such as ethylene, propylene, 4-methyl-1-pentene; Examples include carboxyl group-containing ethylenically monofunctional monomers such as maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester; vinyl acetate; 2-hydroxymethyl-1-butene; methyl vinyl ketone; etc. As other monomers, styrene-based monomers, nitrogen-containing heterocyclic vinyl compounds, and carboxyl group-containing ethylenically monofunctional monomers are preferred, styrene-based monomers and carboxyl group-containing ethylenically monofunctional monomers are more preferred, and styrene-based monomers are even more preferred. These other monomers (constituent units) may have only one type or two or more types. The other monomer (constituent unit) is, for example, 0 mass% or more, preferably 1 mass% or more, among the (meth)acrylic polymer, and, for example, 30 mass% or less, preferably 20 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less.

[0054] In the total composition of the (meth)acrylic polymer, the total content ratio of composition units derived from (meth)acrylic monomers (i.e., composition units derived from (meth)acrylic acid units, (meth)acrylic acid ester units, and derivatives thereof) is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, and even more preferably 75 mass% or more, from the perspective of the transparency of the molded article. There is no particular upper limit, and it may be 100 mass%. In addition, for a (meth)acrylic polymer having units derived from a (meth)acrylic monomer that has become a different unit according to the cyclization reaction described later (i.e., a (meth)acrylic polymer having a ring structure), the total content ratio of constituent units derived from a (meth)acrylic monomer in all constituent units of the (meth)acrylic polymer having a ring structure is preferably 30 mass% or more, more preferably 50 mass% or more, even more preferably 60 mass% or more, even more preferably 70 mass% or more, particularly preferably 75 mass% or more, and preferably 99 mass% or less, more preferably 95 mass% or less, even more preferably 90 mass% or less, and even more preferably 85 mass% or less.

[0055] In the total composition of the (meth)acrylic polymer, the total content ratio of the composition unit derived from the hydroxyl group-introducing derivative of the (meth)acrylic acid ester (preferably α-(1-hydroxyalkyl)alkyl acrylate) is preferably 1 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, even more preferably 10 mass% or more, preferably 70 mass% or less, more preferably 50 mass% or less, and even more preferably 30 mass% or less. In addition, for a (meth)acrylic polymer having units derived from a (meth)acrylic monomer that has become a different unit according to the cyclization reaction described later (i.e., a (meth)acrylic polymer having a ring structure), the total content ratio of constituent units derived from a hydroxyl group-introducing derivative of a (meth)acrylic acid ester in all constituent units of the (meth)acrylic polymer having a ring structure may be 0 mass%, preferably 10 mass% or less, more preferably 8 mass% or less, and even more preferably 5 mass% or less.

[0056] A (meth)acrylic polymer having a ring structure in the main chain that is at least one of a lactone ring structure and a glutaric anhydride structure can be formed, for example, by performing the cyclization reaction described below in a (meth)acrylic polymer having a hydroxyl group, an ester group, and / or a carboxyl group.

[0057] As for the lactone ring structure, for example, a ring of 4 or more and 8 or fewer is preferred in terms of ease of forming the lactone ring structure, a ring of 5 or 6 is more preferred in terms of excellent stability of the ring structure, and a ring of 6 is even more preferred. As for the lactone ring structure of a 6-membered ring, for example, a structure represented by the following formula (1) can be cited.

[0058]

[0059] In the above equation (1), R 1a , R 2a and R 3aEach is independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and said organic residue may include an oxygen atom.

[0060] As for the organic residue in Formula (1), examples include hydrocarbon groups having 1 to 20 carbon atoms that may have substituents. Examples of said hydrocarbon groups include saturated or unsaturated straight-chain, branched, or cyclic aliphatic hydrocarbon groups or aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include, for instance, alkyl groups having 1 to 20 carbon atoms such as methyl groups, ethyl groups, n-propyl groups, isopropyl groups, etc. (preferably alkyl groups having 1 to 10 carbon atoms, more preferably alkyl groups having 1 to 6 carbon atoms); alkenyl groups having 2 to 20 carbon atoms such as ethenyl groups, propenyl groups, etc. (preferably alkenyl groups having 2 to 10 carbon atoms, more preferably alkenyl groups having 2 to 6 carbon atoms); Examples of aromatic hydrocarbon groups include cycloalkyl groups having 3 to 20 carbon atoms, such as cyclopentyl groups and cyclohexyl groups (preferably cycloalkyl groups having 4 to 12 carbon atoms, and more preferably cycloalkyl groups having 5 to 8 carbon atoms); and so on. Examples of aromatic hydrocarbon groups include aryl groups having 6 to 20 carbon atoms, such as phenyl groups, tolyl groups, xylyl groups, naphthyl groups, and biphenyl groups (preferably aryl groups having 6 to 14 carbon atoms, and more preferably aryl groups having 6 to 10 carbon atoms); aralkyl groups having 7 to 20 carbon atoms, such as benzyl groups and phenylethyl groups (preferably aralkyl groups having 7 to 15 carbon atoms, and more preferably aralkyl groups having 7 to 11 carbon atoms). The hydrocarbon groups of these may include oxygen atoms or halogen atoms, and specifically, one or more hydrogen atoms of the hydrocarbon groups may be substituted by at least one group selected from hydroxyl groups, carboxyl groups, ether groups, and ester groups.

[0061] In the lactone ring structure represented by formula (1), since it is easy to obtain a (meth)acrylic polymer with excellent heat resistance, R 1a , R 2a As, independently of each other, it is preferable that it be a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and more preferable that it be a hydrogen atom or a methyl group, and R 3a As for the atom, it is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.

[0062] (Met)acrylic polymers may have only one type of lactone ring structure or two or more types.

[0063] When a (meth)acrylic polymer has a lactone ring structure in its main chain, the content ratio of the lactone ring structure in the polymer is, for example, 1 mass% or more, preferably 5 mass% or more, more preferably 10 mass% or more, and, for example, 70 mass% or less, preferably 50 mass% or less, more preferably 30 mass% or less.

[0064] In addition, the content ratio of the lactone ring structure in the (meth)acrylic polymer can be calculated by the following formula from the polymerization amount of the monomer involved in lactone cyclization (hydroxyl group-containing (meth)acrylic monomer A and (meth)acrylic monomer B in the case of the cyclization reaction of (i) described later) and the lactone cyclization rate.

[0065] Content of lactone ring structure (mass%) = Z1 × Z2 × M R / M m

[0066] (In the formula, Z1 is the mass content ratio of structural units derived from raw monomers involved in lactone cyclization (hydroxyl group-containing (meth)acrylic monomer A and (meth)acrylic monomer B in the case of the cyclization reaction of (i) described below) in the polymer prior to lactone cyclization, and M Ris the food of the lactone ring structural unit that generates (meaning the sum of the lactone ring forming elements and the food of groups other than the main chain that bind to the lactone ring), and M m is the molecular weight (total) of the raw monomers involved in lactone cyclization (hydroxyl group-containing (meth)acrylic monomer A and (meth)acrylic monomer B in the case of the cyclization reaction of (i) described below), and Z2 is the lactone cyclization rate.

[0067] In addition, the content ratio of the lactone ring structure in the (meth)acrylic polymer is determined by a known method, for example, nuclear magnetic resonance ( 1 It can be evaluated by the H-NMR method and / or infrared spectroscopy (IR) method.

[0068] As for the structure of glutaric anhydride, for example, the structure represented by the following formula (2) can be cited.

[0069]

[0070] In the above equation (2), R 4a , R 5a are independently hydrogen atoms or alkyl groups having 1 to 8 carbon atoms.

[0071] As for the alkyl group having 1 to 8 carbon atoms in formula (2), a straight-chain or branched alkyl group may be preferably used, such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc.

[0072] In the anhydrous glutaric acid structure represented by formula (2), since it is easy to obtain a (meth)acrylic polymer with excellent heat resistance, R 4a , R 5a As for the group, it is preferable that it be a hydrogen atom or an alkyl group having 1 to 4 carbon atoms independently of each other, and more preferable that it be a hydrogen atom or a methyl group.

[0073] (Meth)acrylic polymers may have only one type of glutaric anhydride structure or two or more types.

[0074] When a (meth)acrylic polymer has a glutaric anhydride structure in its main chain, the content ratio of the glutaric anhydride structure in the polymer is, for example, 1 mass% or more, preferably 5 mass% or more, more preferably 10 mass% or more, and, for example, 70 mass% or less, preferably 50 mass% or less, more preferably 30 mass% or less.

[0075] In addition, the content ratio of the anhydrous glutaric acid structure in the (meth)acrylic polymer can be obtained, for example, by the method described in Japanese Patent Publication No. 2006-131689.

[0076] In the (meth)acrylic polymer, the content ratio of ring structure units is preferably 5 mass% or more, more preferably 8 mass% or more, even more preferably 10 mass% or more, preferably 70 mass% or less, more preferably 50 mass% or less, even more preferably 45 mass% or less, and even more preferably 30 mass% or less. By keeping the content ratio of ring structure units within the above range, a (meth)acrylic resin composition having excellent heat resistance and excellent mechanical strength can be obtained. Furthermore, regarding the content ratio of ring structure units, the ring structure unit refers to a unit having a ring structure in the main chain of the (meth)acrylic polymer.

[0077] In the (meth)acrylic polymer, the cyclization rate is preferably 95.0 mass% or more, more preferably 95.5 mass% or more, more preferably 96.0 mass% or more, and more preferably 96.5 mass% or more. There is no particular upper limit, and it may be 100 mass%.

[0078] The cyclicity rate is based on the amount of mass loss that occurs when all hydroxyl groups are dealolated or dehydrated with alcohol or water from the polymer composition obtained, for example, from the polymer composition obtained from polymerization, and can be obtained from the mass loss caused by the dealolation or dehydration reaction from 150°C, before the mass loss begins in dynamic TG measurement, to 300°C, before the decomposition of the polymer begins. That is, the mass loss rate between 150°C and 300°C is measured in dynamic TG measurement of a polymer having a ring structure, and the obtained measured mass loss rate is set as (X). Meanwhile, the theoretical mass loss rate (i.e., the mass loss rate calculated by assuming that 100% dealolation or dehydration reaction occurred in the composition) when assuming that all hydroxyl groups included in the polymer composition participate in ring formation and thus undergo dealolation or dehydration from the composition of the polymer is set as (Y). In addition, the theoretical mass loss rate (Y) can be calculated, more specifically, from the molar ratio of the raw material monomer having a structure (hydroxyl group) involved in the dealolysis or dehydration reaction in the polymer, that is, the content of the said raw material monomer in the polymer composition. By substituting these values ​​(X, Y) into the formula: 1 - (actual mass loss rate (X) / theoretical mass loss rate (Y)) to obtain the value and expressing it as %, the cyclization rate (dealolysis or dehydration reaction rate) is obtained.

[0079] In the total composition of the (meth)acrylic polymer, the total content ratio of the composition unit derived from the (meth)acrylic monomer (preferably a unit derived from the (meth)acrylic acid ester) and the ring structure unit is preferably 90 mass% or more, more preferably 93 mass% or more, and even more preferably 95 mass% or more. By doing so, it becomes easier to increase the transparency and heat resistance of the (meth)acrylic polymer.

[0080] A (meth)acrylic polymer may have at least one of a lactone ring structure and a glutaric anhydride structure as a ring structure, but it is more preferable to have a lactone ring structure from the perspective of improving the heat resistance or optical properties of the (meth)acrylic resin composition.

[0081] The weight average molecular weight (Mw) of the (meth)acrylic polymer is, for example, 80,000 or more, preferably 100,000 or more, more preferably 105,000 or more, and even more preferably 110,000 or more, and, for example, 300,000 or less, preferably 250,000 or less, and more preferably 200,000 or less. By having the weight average molecular weight of the (meth)acrylic polymer within the above range, a (meth)acrylic resin composition can be obtained that maintains the necessary strength as a resin while also having good fluidity during molding.

[0082] The molecular weight distribution of the (meth)acrylic polymer (Mw / Mn; Mw represents the weight average molecular weight of the (meth)acrylic polymer and Mn represents the number average molecular weight of the (meth)acrylic polymer) is, for example, 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less, and, for example, 1.1 or more, preferably 1.2 or more, more preferably 2.0 or more.

[0083] In the (meth)acrylic resin composition, the content ratio of the (meth)acrylic polymer having a ring structure is, for example, 50 mass% or more, preferably 70 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more. In addition, the upper limit of the content ratio of the (meth)acrylic polymer having a ring structure in the (meth)acrylic resin composition is less than 100 mass%.

[0084] 1.2 phosphorus atom

[0085] The (meth)acrylic resin composition of the present invention contains phosphorus atoms. It is preferable that the phosphorus atoms originate from a catalyst used in the cyclization reaction of the (meth)acrylic polymer.

[0086] In the (meth)acrylic resin composition, the phosphorus atom content is 1.0 ppm or more and 50 ppm or less, preferably 1.5 ppm or more and 45 ppm or less, more preferably 2.0 ppm or more and 40 ppm or less, and even more preferably 20 ppm or more and 34 ppm or less. By keeping the phosphorus atom content within the above range, the cyclization rate can be increased and the content ratio of ring structure units in the (meth)acrylic polymer can be set to an appropriate range, thereby obtaining a (meth)acrylic resin composition with excellent heat resistance and excellent mechanical strength. Furthermore, by keeping the phosphorus atom content 50 ppm or less, the occurrence of silver streaks is suppressed and a (meth)acrylic resin composition with excellent stability can be obtained. Specifically, if the phosphorus atom content is 50 ppm or less, the corrosive phosphorus atom is sufficiently small, so the stability is excellent. In addition, the phosphorus atom content is specified to two significant figures.

[0087] 1.3 Compounds represented by formula (I)

[0088] The (meth)acrylic resin composition of the present invention may include a compound represented by the following formula (I), but it is preferable not to include it as much as possible. Specifically, the content of the compound represented by formula (I) in the (meth)acrylic resin composition is 95 ppm or less, preferably 90 ppm or less, more preferably 80 ppm or less, even more preferably 60 ppm or less, and most preferably 0 ppm (i.e., not detected by the method described in the examples). By keeping the content of the compound represented by formula (I) within the above range, the adhesion between the (meth)acrylic resin composition and the roll during molding is improved, and the occurrence of roll contamination can be suppressed. Furthermore, the specificity of the compound represented by formula (I) and its content can be determined by the method described in the examples below. Additionally, when expressed in ppm, the first decimal place is rounded up to specify it.

[0089]

[0090] [Equation (I), R 1 represents an aliphatic hydrocarbon group with 13 or more carbon atoms, or an aromatic hydrocarbon group with 6 or more carbon atoms.

[0091] R in Equation (I) 1 The aliphatic hydrocarbon group represented by may be saturated or unsaturated, and may be chain-like or cyclic.

[0092] R 1Examples of aliphatic hydrocarbon groups having 13 or more carbon atoms, represented as such, include alkyl groups having 13 or more carbon atoms, such as tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups; alkenyl groups having 13 or more carbon atoms, such as tridecenyl, tetradecenyl, pentadecyl, hexadecenyl, octadecenyl, and octadecadienyl groups; and cycloalkyl groups having 13 or more carbon atoms, such as cyclotridecyl, cyclotetradecyl, cyclopentadecyl, cyclohexadecyl, cycloheptadecyl, and cyclooctadecyl groups.

[0093] R 1 Examples of aromatic hydrocarbon groups having 6 or more carbon atoms, represented as such, include aryl groups having 6 or more carbon atoms such as phenyl groups, tolyl groups, xylyl groups, naphthyl groups, and biphenyl groups; aralkyl groups having 7 or more carbon atoms such as benzyl groups and phenylethyl groups; etc.

[0094] 1.4 Compounds represented by formula (II)

[0095] The (meth)acrylic resin composition of the present invention may include a compound represented by the following formula (II), but it is preferable not to include it as much as possible. Specifically, the content of the compound represented by formula (II) in the (meth)acrylic resin composition is 95 ppm or less, preferably 90 ppm or less, more preferably 80 ppm or less, even more preferably 60 ppm or less, and most preferably 0 ppm (i.e., not detected by the method described in the examples). By keeping the content of the compound represented by formula (II) within the above range, roll contamination can be further reduced, and furthermore, the occurrence of silver streaks is further suppressed, and a (meth)acrylic resin composition with excellent stability can be obtained. In addition, the specificity and content of the compound represented by formula (II) can be determined by the same method as for the compound represented by formula (I). In addition, when expressed in ppm, the first decimal place is rounded up to specify.

[0096]

[0097] [In Equation (II), R 2 represents an aliphatic hydrocarbon group with 3 to 12 carbon atoms.

[0098] R in Equation (II) 2 The aliphatic hydrocarbon group represented by may be saturated or unsaturated, and may be chain-like or cyclic.

[0099] R 2 Examples of aliphatic hydrocarbon groups having 3 to 12 carbon atoms, represented as such, include alkyl groups having 3 to 12 carbon atoms, such as n-propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group; alkenyl groups having 3 to 12 carbon atoms, such as propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group; cycloalkyl groups having 3 to 12 carbon atoms, such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group; etc.

[0100] R 2 As for the aliphatic hydrocarbon group having 3 to 10 carbon atoms, an aliphatic hydrocarbon group having 3 to 8 carbon atoms is more preferable, and an aliphatic hydrocarbon group having 3 to 7 carbon atoms is even more preferable.

[0101] 1.5 other alcohols

[0102] The (meth)acrylic resin composition of the present invention may include an alcohol (referred to as "other alcohol") other than the compound represented by Formula (I) and the compound represented by Formula (II). In particular, when the other alcohol is a low molecular weight alcohol such as methanol or ethanol, it does not cause roll contamination because it is removed by volatilization during heating in molding. However, the content of the other alcohol is preferably lower, for example, 1000 ppm or less, preferably 500 ppm or less, more preferably 300 ppm or less, and may be 0 ppm.

[0103] 1.6 Other Ingredients

[0104] The (meth)acrylic resin composition of the present invention may include other components as needed, in addition to the (meth)acrylic polymer having the ring structure described above or phosphorus atoms.

[0105] The (meth)acrylic resin composition of the present invention may contain, as the other component, for example, a (meth)acrylic polymer that does not have a ring structure or a polymer other than a (meth)acrylic polymer. Polymers other than (meth)acrylic polymers include, for example, olefinic polymers such as polyethylene, polypropylene, ethylene-propylene polymer, and poly(4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and vinyl chlorinated resin; styrene-based polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon 6, nylon 66, and nylon 610; polyacetals; polycarbonates; polyphenylene oxide; polyphenylene sulfide; and polyetheretherketone. Examples include polysulfone; polyethersulfone; polyoxyphenzyrene; polyamideimide; cycloolefin polymer; cellulose derivative; rubbery polymers such as ABS resin or ASA resin blended with polybutadiene-based rubber or (meth)acrylic rubber. In the (meth)acrylic resin composition, the content of a polymer other than the (meth)acrylic polymer having a ring structure is preferably 100 parts by weight or less, more preferably 40 parts by weight or less, even more preferably 10 parts by weight or less, even more preferably 5 parts by weight or less, and may be 0 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer having a ring structure.

[0106] In addition, the (meth)acrylic resin composition of the present invention may contain various additives as long as they are within a range that does not impair the effects of the present invention. As additives, for example, ultraviolet absorbers; antioxidants such as phenolic antioxidants (e.g., hydroquinone, 2,6-di-t-butyl-p-cresol, tocopherol, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, etc.), phosphorus-based antioxidants (e.g., triphenylphosphite, tris(2,4-di-t-butylphenyl)phosphite, etc.), sulfur-based antioxidants (e.g., 2-mercaptobenzimidazole, dilauryl 3,3'-thiodipropionate, etc.); stabilizers such as light stabilizers, weather stabilizers, heat stabilizers, etc.; reinforcing materials such as glass fibers, carbon fibers, etc.; near-infrared absorbers; Examples include flame retardants such as tris(dibromopropyl)phosphate, trialyl phosphate, and antimony oxide; phase difference modifiers such as phase difference enhancers, phase difference reducers, and phase difference stabilizers; antistatic agents including anionic, cationic, and nonionic surfactants; compatibilizers; stabilizers; coloring agents such as inorganic pigments, organic pigments, and dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers or inorganic fillers; etc. The content ratio of each additive in 100 mass% of the solid content of the resin composition is preferably within the range of 0 mass% or more and 5 mass% or less, more preferably 0 mass% or more and 2 mass% or less.

[0107] Examples of the above-mentioned ultraviolet absorbers include benzophenone-based compounds, salicylate-based compounds, benzoate-based compounds, triazole-based compounds, and triazine-based compounds, and known ultraviolet absorbers may be used. Examples of benzophenone-based compounds include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, etc. Examples of salicylate-based compounds include pt-butylphenyl salicylate, etc. Examples of benzoate-based compounds include 2,4-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate, etc. As triazole compounds, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl(Il))phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl(Il))-p-cresol, 2-(2H-benzotriazole-2-yl(Il))-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazole-2-yl(Il)-4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazole-2-yl(Il)]-4-methyl-6-t-butylphenol, Examples include 2-(2H-benzotriazole-2-yl(Il))-4,6-di-t-butylphenol, 2-(2H-benzotriazole-2-yl(Il))-4-(1,1,3,3-tetramethylbutyl)phenol, etc. Examples of triazine compounds include 2-[4,6-bis(biphenyl-4-yl(Il))-1,3,6-tri-2-yl(Il)]-5-[(2-ethylhexyl)oxy]phenol, 2-mono(hydroxyphenyl)-1,3,5-triazine compound, 2,4-bis(hydroxyphenyl)-1,3,5-triazine compound, 2,4,6-tris(hydroxyphenyl)-1,3,5-triazine compound, etc.Examples of commercially available UV absorbers include the triazine-based UV absorbers Tinuvin (registered trademark) 1577, Tinuvin (registered trademark) 460, Tinuvin (registered trademark) 477 (manufactured by BASF Japan), AdekaStab (registered trademark) LA-F70 (manufactured by ADEKA), and the triazole-based UV absorber AdekaStab (registered trademark) LA-31 (manufactured by ADEKA). One type of UV absorber may be used, or two or more types may be used in combination.

[0108] On the other hand, in order to more effectively suppress roll contamination, the (meth)acrylic resin composition of the present invention preferably does not include hindered phenol compounds and / or compounds that are sources of hindered phenol compounds. This is because hindered phenol compounds are a cause of roll contamination. Examples of hindered phenol compounds include hindered phenol-based antioxidants such as 2,6-di-t-butyl-p-cresol and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene. Examples of compounds that are sources of hindered phenol compounds include organic phosphorus compounds having a hindered phenol group, and specifically, phosphorus-based antioxidants having a hindered phenol group such as tris(2,4-di-t-butylphenyl)phosphite. In addition, a hindered phenol compound is a phenol compound having at least one sterically bulky substituent, such as a tertiary alkyl group like a t-butyl group, and a phenol compound having at least one tertiary alkyl group is preferred.

[0109] 1.7 Characteristics

[0110] The (meth)acrylic resin composition of the present invention has a phosphorus atom content of 1.0 ppm or more and 50 ppm or less, a compound represented by the above formula (I) has a content of 95 ppm or less, and preferably a compound represented by the above formula (II) has a content of 95 ppm or less, thereby reducing roll contamination and further suppressing the occurrence of silver streaks, and having excellent stability.

[0111] The weight average molecular weight (Mw) of the (meth)acrylic resin composition is, for example, 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, even more preferably 115,000 or more, and even more preferably 120,000 or more, and, for example, 300,000 or less, preferably 250,000 or less, and more preferably 200,000 or less. By having the weight average molecular weight of the (meth)acrylic resin composition within the above range, it is possible to obtain a (meth)acrylic resin composition that maintains the strength required for the resin while also having good fluidity during molding.

[0112] The number average molecular weight (Mn) of the (meth)acrylic resin composition is, for example, 30,000 or more, preferably 35,000 or more, more preferably 40,000 or more, and, for example, 250,000 or less, preferably 200,000 or less, more preferably 150,000 or less. By having the number average molecular weight of the (meth)acrylic resin composition within the above range, it is possible to obtain a (meth)acrylic resin composition that maintains the strength required for the resin while also having good fluidity during molding.

[0113] The molecular weight distribution of the (meth)acrylic resin composition (Mw / Mn; Mw represents the weight average molecular weight of the (meth)acrylic resin composition and Mn represents the number average molecular weight of the (meth)acrylic resin composition) is, for example, 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less, and there is no particular lower limit, for example, it may be 1.1 or more.

[0114] It is preferable that the (meth)acrylic resin composition has a glass transition temperature of 110°C or higher. By having a glass transition temperature of 110°C or higher, the heat resistance of the resin composition is increased. The (meth)acrylic resin composition may have multiple glass transition temperatures of 110°C or higher. The glass transition temperature of the (meth)acrylic resin composition is more preferably 120°C or higher, and even more preferably 123°C or higher. From the perspective of improving processability during molding, the glass transition temperature of the (meth)acrylic resin composition is preferably less than 300°C, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0115] The (meth)acrylic resin composition has good adhesion because the content of the compound represented by formula (I) is 95 ppm or less.

[0116] Since the (meth)acrylic resin composition has good adhesion, roll contamination during molding is suppressed. If contamination occurs on the roll during molding, there is a risk that the appearance (smoothness) of the molded body may be damaged, or that production efficiency may decrease due to stopping the line to remove contamination from the roll surface.

[0117] 2. Method for preparing a (meth)acrylic resin composition

[0118] The method for preparing a (meth)acrylic resin composition of the present invention comprises a cyclization process in which a cyclization reaction is performed on a (meth)acrylic polymer and at least one ring structure, such as a lactone ring structure and a glutaric anhydride structure, is formed in the main chain of the (meth)acrylic polymer, and a specific cyclization catalyst is used as a catalyst for the cyclization reaction.

[0119] In addition, the method for manufacturing the (meth)acrylic resin composition of the present invention preferably includes a polymerization process in which the (meth)acrylic polymer is formed by polymerizing a (meth)acrylic monomer.

[0120] 2.1 (Matte)Acrylic Monomers

[0121] The (meth)acrylic monomer is a polymerization component, and as the (meth)acrylic monomer, a monomer similar to the (meth)acrylic monomer described above may be cited, and the preferred embodiment is also the same.

[0122] Specifically, the (meth)acrylic monomer used for polymerization may be a single monomer or a combination of two or more monomers. The (meth)acrylic monomer used for polymerization preferably contains at least (meth)acrylic acid or a (meth)acrylic acid ester, and it is more preferable to contain at least a (meth)acrylic acid ester. Furthermore, the (meth)acrylic monomer used for polymerization preferably contains a (meth)acrylic acid ester derivative in addition to the (meth)acrylic acid and / or (meth)acrylic acid ester. In particular, the (meth)acrylic monomer used for polymerization preferably contains a (meth)acrylic acid ester and a hydroxyl group-introducing derivative of the (meth)acrylic acid ester. The ratio of the total amount of (meth)acrylic monomer to the total amount of monomer components used in polymerization is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, and even more preferably 75 mass% or more, with no particular upper limit, and may be 100 mass%. The content ratio of (meth)acrylic acid and / or (meth)acrylic acid ester in the (meth)acrylic monomer used in polymerization is, for example, 30 mass% or more, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 65 mass% or more, even more preferably 70 mass% or more, particularly preferably 75 mass% or more, and, for example, 100 mass% or less, preferably 95 mass% or less, more preferably 90 mass% or less, and even more preferably 85 mass% or less. The content ratio of (meth)acrylic acid ester derivative (preferably α-(1-hydroxyalkyl)alkyl acrylate) to the total amount of monomer components used in polymerization is, for example, 1 mass% or more, preferably 5 mass% or more, more preferably 8 mass% or more, even more preferably 10 mass% or more, and, for example, 70 mass% or less, preferably 50 mass% or less, more preferably 30 mass% or less, even more preferably 20 mass% or less.

[0123] As for the monomer component that is a polymerization component, it may include a monomer other than the (meth)acrylic monomer mentioned above, and as the other monomer, a monomer similar to the other monomer described above may be cited, and the preferred embodiment is also the same.

[0124] The other monomer used in polymerization may be just one type or two or more types. The ratio of the total amount of other monomers to the total amount of monomer components is, for example, 0 mass% or more, preferably 1 mass% or more, and, for example, 30 mass% or less, preferably 20 mass% or less, more preferably 10 mass% or less.

[0125] 2.2 Polymerization Initiator

[0126] When polymerizing a (meth)acrylic monomer, a polymerization initiator may be used as needed.

[0127] As polymerization initiators, for example, azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, dimethyl-2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanopentanic acid); persulfates such as potassium persulfate; Organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyoctoate, t-amylperoxyisononanoate, t-amylperoxyisopropyl carbonate, and t-amylperoxy2-ethylhexyl carbonate may be used. One of these may be used alone, or two or more may be used in combination. Among these, it is preferable to use an organic peroxide with strong hydrogen drawing power.

[0128] The amount of polymerization initiator used is, for example, 500 ppm or more, preferably 1000 ppm or more, more preferably 1500 ppm or more, with respect to the total amount of monomer components, in order to increase the polymerization rate and reduce the residual amount of unreacted monomer components. In addition, the amount of polymerization initiator used is, for example, 2 mass% or less, preferably 1 mass% or less, more preferably 0.5 mass% or less, with respect to the total amount of monomer components.

[0129] To promote the decomposition of the polymerization initiator, a decomposition agent of the polymerization initiator, such as a reducing agent like sodium bisulfite; a transition metal salt like ferrous sulfate; etc., may be added to the reaction system in an appropriate amount.

[0130] 2.3 Chain Transfer Agent

[0131] To adjust the weight-average molecular weight of the (meth)acrylic polymer, a chain transfer agent may be added to the reaction system. By adding a chain transfer agent to the reaction system, the (meth)acrylic polymer can be reduced to a lower molecular weight. Examples of chain transfer agents include organic thiol compounds; halogen compounds such as carbon tetrachloride, carbon tetrabromide, methylene chloride, bromoform, and bromotrichloroethane; and unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, γ-terpinene, dipentene, and terpinolene. These chain transfer agents may be used individually or in combination of two or more. Among these, organic thiol compounds are preferred because they can suppress a decrease in conversion rate.

[0132] Examples of the above organic thiol compounds include monofunctional thiol compounds and polyfunctional thiol compounds.

[0133] Examples of the above monofunctional thiol compounds include monofunctional thiol compounds having an aromatic ring, such as thiophenol, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 3-mercapto-1,2,4-triazole, and octyl thioglycolate; and aliphatic monofunctional thiol compounds not having an aromatic ring. Furthermore, examples of the above aliphatic monofunctional thiol compounds include monofunctional thiol compounds containing heteroatoms between carbon atoms of an aliphatic hydrocarbon group, such as octyl 2-mercaptopropionate, octyl 3-mercaptopropionate, 2-ethylhexyl ester of mercaptopropionate, and 2-mercaptoethyl ester of octanoic acid. Examples of alkyl thiol compounds that do not contain heteroatoms between carbon atoms of an aliphatic hydrocarbon group include butanethiol, octanethiol, 1-dodecanethiol (also called n-dodecyl mercaptan), octadecanthiol, and cyclohexyl mercaptan. Examples of the above heteroatoms include oxygen atoms and nitrogen atoms.

[0134] Examples of the above-mentioned polyfunctional thiol compounds include polyfunctional thiol compounds having an aromatic ring, such as 1,4-dimethylmercaptobenzene and 1,3,5-triazine-2,4,6-trithiol; and aliphatic polyfunctional thiol compounds not having an aromatic ring, such as 1,8-dimercapto-3,6-dioxaoctan, ethylene glycol bisthioglycolate, trimethylolpropane tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tristhiobutanate, pentaerythritol tetrakis(4-mercaptobutanate), pentaerythritol tetrakis(6-mercaptohexanate), and dipentaerythritol hexakis(3-mercaptopropionate).

[0135] As for the organic thiol compound, a monofunctional thiol compound is preferred, an aliphatic monofunctional thiol compound is more preferred, and an alkyl thiol compound is even more preferred.

[0136] The amount of chain transfer agent used is, for example, 200 ppm or more, preferably 400 ppm or more, more preferably 500 ppm or more, with respect to the total amount of monomer components, and, for example, 5 mass% or less, preferably 1 mass% or less, more preferably 0.5 mass% or less.

[0137] The ratio of the amount of chain transfer agent and the amount of polymerization initiator used (amount of chain transfer agent / amount of polymerization initiator used; mass ratio) is preferably 0.10 or more, more preferably 0.15 or more, even more preferably 0.20 or more, and also preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less. By keeping the ratio of the amount of chain transfer agent and the amount of polymerization initiator used within the above range, the polymerization rate can be appropriately maintained and the molecular weight distribution can also be narrowed.

[0138] 2.4 Polymerization Reaction (Polymerization Process)

[0139] As for the polymerization method of (meth)acrylic monomers, batch polymerization or continuous polymerization may be used, but when using a chain transfer agent, batch polymerization is preferred in order to reduce the amount of unreacted chain transfer agent remaining.

[0140] In addition, the polymerization of (meth)acrylic monomers can be bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, but solution polymerization is preferred because it has high safety and a low risk of foreign matter contamination.

[0141] Solvents that can be used in solution polymerization include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether solvents such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and anisole; ester solvents such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; alcohol solvents such as methanol, ethanol, isopropanol, and n-butanol; nitrile solvents such as acetonitrile, propionitrile, butyronitrile, and benzonitrile; halogen solvents such as chloroform and dichloromethane; and dimethyl sulfoxide. As polymerization solvents, aromatic hydrocarbon solvents and ketone solvents are preferred, more preferably aromatic hydrocarbon solvents, particularly preferably toluene. As polymerization solvents, only one type may be used, or two or more types may be used in combination.

[0142] The total concentration of monomers (monomer components) in the polymerization reaction solution is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 30 mass% or more, and, for example, 90 mass% or less, preferably 80 mass% or less, more preferably 70 mass% or less. The amount of solvent used in the polymerization reaction is not particularly limited as long as the total concentration of monomers in the polymerization reaction solution is within the above range.

[0143] The method of adding monomers and solvents used as needed is not particularly limited. As for the method of addition, the entire amount of each may be added as an initial input, or a certain amount may be added as an initial input and the remainder added in a lump sum or continuously into the reaction system during the polymerization reaction. The continuous addition may be continuous or intermittent, such as divided addition, but it is preferable to be continuous or intermittent with an interval of 10 minutes or less, and it is more preferable to be continuous.

[0144] In addition, the method of adding the polymerization initiator and chain transfer agent used as needed is not particularly limited. As for the method of addition, the entire amount may be added as an initial input, a certain amount may be added as an initial input and the remainder added collectively or continuously into the reaction system during the polymerization reaction, or the entire amount may be introduced into the reaction system by addition. The above-mentioned addition may be continuous or intermittent, such as divided addition, but it is preferable to be continuous or intermittent with an interval of 10 minutes or less, and continuous is more preferable. In addition, in order to narrow the molecular weight distribution of the (meth)acrylic polymer obtained, it is preferable to add the entire amount of the polymerization initiator continuously into the reaction system during the polymerization reaction, or to add a certain amount as an initial input and the remainder continuously into the reaction system during the polymerization reaction.

[0145] The atmosphere used when polymerizing (meth)acrylic monomers is not particularly limited, but from the perspective of increasing the efficiency of the polymerization reaction, it is preferable to use an inert gas such as nitrogen gas.

[0146] When polymerizing (meth)acrylic monomers, the polymerization temperature is, for example, 40°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and when a polymerization initiator is used, it is preferable to set the temperature at or above the 10-hour half-life temperature of the polymerization initiator used. In addition, the 10-hour half-life temperature refers to the temperature at which the half-life of the polymerization initiator becomes 10 hours. Furthermore, the polymerization temperature is, for example, 180°C or lower, preferably 150°C or lower, more preferably 120°C or lower, and when a solvent is used, it is preferable to set the temperature at or below the reflux temperature of the solvent used.

[0147] The polymerization time when polymerizing (meth)acrylic monomers is not particularly limited and can be set appropriately depending on the progress of the polymerization reaction, but is typically about 2 to 8 hours.

[0148] After adding all monomers and, if necessary, a polymerization initiator, a chain transfer agent, and a solvent, aging may be performed as needed. Aging further improves the conversion rate of the monomers. During the aging process, it is desirable to continue stirring at a suitable temperature, for example, about ±30°C of the polymerization temperature (preferably at the polymerization temperature or above the polymerization temperature). The aging time is, for example, 0 hours or more and 10 hours or less, preferably 1 hour or more and 5 hours or less.

[0149] The monomer conversion rate at the end of the reaction is, for example, 80% or more, preferably 85% or more, and more preferably 88% or more.

[0150] In the total composition of the (meth)acrylic polymer obtained by the polymerization reaction, the total content ratio of constituent units derived from (meth)acrylic monomers is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, and even more preferably 75 mass% or more, from the perspective of the transparency of the molded article. There is no particular upper limit, and it may be 100 mass%. In addition, in the total composition of the (meth)acrylic polymer obtained by the polymerization reaction, the total content ratio of constituent units derived from (meth)acrylic acid ester derivatives (preferably α-(1-hydroxyalkyl)alkyl acrylate) is preferably 5 mass% or more, more preferably 8 mass% or more, even more preferably 10 mass% or more, and for example 70 mass% or less, preferably 50 mass% or less, more preferably 30 mass% or less, and even more preferably 20 mass% or less.

[0151] 2.5 Cyclolysis Catalyst

[0152] In the present invention, C phosphoric acid is used as a cyclization catalyst. 3-12 Alkyl ester, C phosphoric acid 3-12 Alkyl esters and C hypophosphorus 3-12By using at least one selected from the group consisting of alkyl esters, the cyclization reaction can be carried out efficiently, and the decrease in adhesion of the obtained (meth)acrylic resin composition can be suppressed.

[0153] C phosphoric acid 3-12 Examples of alkyl esters include monopropyl phosphate, dipropyl phosphate, tripropyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, triisopropyl phosphate, monobutyl phosphate, dibutyl phosphate, tributyl phosphate, monotert-butyl phosphate, ditert-butyl phosphate, tritert-butyl phosphate, monopentyl phosphate, dipentyl phosphate, tripentyl phosphate, monohexyl phosphate, dihexyl phosphate, trihexyl phosphate, monoheptyl phosphate, diheptyl phosphate, triheptyl phosphate, monooctyl phosphate, dioctyl phosphate, trioctyl phosphate, etc. C phosphate 3-12 As an alkyl ester, C phosphoric acid 3-10 An alkyl ester is preferred, and C phosphoric acid 3-8 An alkyl ester is more preferable, and C phosphoric acid 3-7 Alkyl esters are more preferable. C phosphoric acid 3-8 Alkyl esters are C phosphate 3-8 Straight-chain alkyl esters are preferred, and C phosphoric acid 3-8 Monolinear alkyl ester, C phosphate 3-8 Dizygous alkyl esters are more preferable. C phosphoric acid 3-7 Alkyl esters are C phosphate 3-7 Straight-chain alkyl esters are preferred, and C phosphoric acid 3-7 Monolinear alkyl ester, C phosphate 3-7 Digic-chain alkyl esters are more preferred. C phosphoric acid 3-12 Among the alkyl esters, monobutyl phosphate and dibutyl phosphate are particularly preferred.

[0154] C phosphoric acid 3-12Examples of alkyl esters include monopropyl phosphite, dipropyl phosphite, tripropyl phosphite, monoisopropyl phosphite, diisopropyl phosphite, triisopropyl phosphite, monobutyl phosphite, dibutyl phosphite, tributyl phosphite, monotert-butyl phosphite, ditert-butyl phosphite, tritert-butyl phosphite, monopentyl phosphite, dipentyl phosphite, tripentyl phosphite, monohexyl phosphite, dihexyl phosphite, trihexyl phosphite, monoheptyl phosphite, diheptyl phosphite, triheptyl phosphite, monooctyl phosphite, dioctyl phosphite, trioctyl phosphite, etc. C phosphite 3-12 As an alkyl ester, C phosphoric acid 3-10 An alkyl ester is preferred, and C phosphoric acid 3-8 An alkyl ester is more preferable, and C phosphoric acid 3-7 Alkyl esters are more preferable. C phosphoric acid 3-8 The alkyl ester is C phosphoric acid 3-8 Straight-chain alkyl esters are more preferable, and C phosphoric acid 3-8 Monolinear alkyl ester, C phosphoric acid 3-8 Digic-chain alkyl esters are more preferable. C phosphoric acid 3-7 The alkyl ester is C phosphoric acid 3-7 A straight-chain alkyl ester is preferred, and C phosphoric acid 3-7 Monolinear alkyl ester, C phosphoric acid 3-7 Digic-chain alkyl esters are more preferable. C phosphoric acid 3-12 Among the alkyl esters, monobutyl phosphite and dibutyl phosphite are particularly preferred.

[0155] C hypophosphorus acid 3-12Examples of alkyl esters include monopropyl hypophosphorus, dipropyl hypophosphorus, tripropyl hypophosphorus, monoisopropyl hypophosphorus, diisopropyl hypophosphorus, triisopropyl hypophosphorus, monobutyl hypophosphorus, dibutyl hypophosphorus, tributyl hypophosphorus, monotert-butyl hypophosphorus, ditert-butyl hypophosphorus, tritert-butyl hypophosphorus, monopentyl hypophosphorus, dipentyl hypophosphorus, tripentyl hypophosphorus, monohexyl hypophosphorus, dihexyl hypophosphorus, trihexyl hypophosphorus, monoheptyl hypophosphorus, diheptyl hypophosphorus, triheptyl hypophosphorus, monooctyl hypophosphorus, dioctyl hypophosphorus, trioctyl hypophosphorus, etc. C hypophosphorus 3-12 As an alkyl ester, C hypophosphorusic acid 3-10 An alkyl ester is preferred, and C hypophosphoric acid 3-8 An alkyl ester is more preferable, and C hypophosphoric acid 3-7 Alkyl esters are more preferable. C hypophosphorous acid 3-8 The alkyl ester is C hypophosphorus 3-8 Straight-chain alkyl esters are more preferable, and C hypophosphoric acid 3-8 Monolinear alkyl ester, C hypophosphoric acid 3-8 Digic-chain alkyl esters are more preferable. C hypophosphoric acid 3-7 The alkyl ester is C hypophosphorus 3-7 Straight-chain alkyl esters are more preferable, and C hypophosphoric acid 3-7 Monolinear alkyl ester, C hypophosphoric acid 3-7 Digic-chain alkyl esters are more preferable. C hypophosphoric acid 3-12 Among the alkyl esters, monobutyl hypophosphite and dibutyl hypophosphite are particularly preferred.

[0156] A single type of cyclization catalyst may be used, or two or more types may be used in combination. When two or more types are used in combination, one of them may be stearyl phosphate. This is because one of the concepts of the present invention is to reduce the proportion of stearyl phosphate in the total amount of the cyclization catalyst compared to conventional methods.

[0157] As a cyclization catalyst, C phosphoric acid is considered due to its high catalytic activity. 3-12An alkyl ester is preferred.

[0158] As for the decomposition temperature of the cyclization catalyst, it is preferably 160°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher, and there is no particular upper limit, and for example, it may be 300°C or lower. For example, the decomposition temperature of butyl phosphate is 220°C and the decomposition temperature of octyl phosphate is 247°C.

[0159] 2.6 Cyclolysis Reaction (Cyclolysis Process)

[0160] By heating the (meth)acrylic polymer after the completion of the above polymerization reaction in the presence of the cyclization catalyst, dehydration condensation or dealolysis condensation is generated, and a (meth)acrylic polymer having a ring structure in the main chain that is at least one of a lactone ring structure and a glutaric anhydride structure is formed.

[0161] Specifically, in a (meth)acrylic polymer formed by a polymerization process, at least one of the following cyclization reactions (i) and (ii) is performed.

[0162] (i) Cyclic reaction forming a lactone ring structure between a hydroxyl group and an ester or carboxyl group

[0163] (ii) Cyclic reaction between a carboxyl group and an ester group or another carboxyl group to form a glutaric anhydride structure

[0164] In the case of the cyclization reaction of (i) above, for example, a hydroxyl group-containing (meth)acrylic monomer A, such as α-(1-hydroxyalkyl)alkyl acrylate, is first homopolymerized in the polymerization reaction, or the hydroxyl group-containing (meth)acrylic monomer A is copolymerized with (meth)acrylic acid, (meth)acrylic acid ester, or (meth)acrylic monomer B, and a hydroxyl group and an ester group or a carboxyl group are introduced into the molecular chain of the (meth)acrylic polymer. Then, in the cyclization reaction, a lactone ring structure can be formed by causing a dealolysis or dehydration cyclization condensation between the hydroxyl group and the ester group or the carboxyl group.

[0165] As for the hydroxyl group-containing (meth)acrylic monomer A in the cyclization reaction of (i), hydroxyl group-introduced derivatives of the aforementioned (meth)acrylic acid ester may be cited, and the preferred embodiment thereof is also the same. Furthermore, as for the (meth)acrylic monomer B, the aforementioned (meth)acrylic acid and (meth)acrylic acid ester may be cited, and the preferred embodiment thereof is also the same.

[0166] In the case of the cyclization reaction of (ii) above, for example, first, (meth)acrylic acid is homopolymerized in the polymerization reaction to introduce carboxyl groups into the molecular chain of the (meth)acrylic polymer, or (meth)acrylic monomer B, such as (meth)acrylic acid or (meth)acrylic acid ester, is polymerized (preferably copolymerized) to introduce carboxyl groups and ester groups into the molecular chain of the (meth)acrylic polymer. Then, in the cyclization reaction, a glutaric anhydride structure can be formed by causing dehydration cyclization condensation between the two carboxyl groups or by causing dealolation between the carboxyl group and the ester group.

[0167] (ii) As the (meth)acrylic monomer B in the cyclization reaction of (ii), the aforementioned (meth)acrylic acid and (meth)acrylic acid ester may be used, and the preferred embodiment is the same.

[0168] In addition, if the (meth)acrylic polymer has a double bond portion, an ester group, a carboxyl group, or an acid anhydride group, the hydroxyl group, ester group, or carboxyl group that will react later in the cyclization reaction may be introduced into the (meth)acrylic polymer before the cyclization reaction by means of the addition of a hydroxyl group to the double bond portion, the hydrolysis of an ester group, or the esterification of a carboxyl group or an acid anhydride group.

[0169] In addition, in the above cyclization reaction, at least some of the hydroxyl groups, ester groups, and / or carboxyl groups of the (meth)acrylic polymer may react, and the reaction may be performed such that the content ratio of the aforementioned ring structure unit and the cyclization rate in the (meth)acrylic polymer are within the range.

[0170] The cyclization reaction may be carried out in the presence of a solvent, and the solvents available for use in the cyclization reaction may be of the same type as the solvents available for use in the aforementioned polymerization reaction, and the preferred mode is also the same.

[0171] When the above polymerization reaction is carried out in solution polymerization, the solvent used in the solution polymerization may be removed first and then a new solvent may be added, or the solvent used in the solution polymerization may be continued as a solvent in the cyclization reaction, but in terms of production efficiency, it is preferable to continue using the solvent used in the solution polymerization as a solvent in the cyclization reaction.

[0172] The concentration of the (meth)acrylic polymer in the cyclization reaction solution is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 30 mass% or more, and, for example, 90 mass% or less, preferably 80 mass% or less, more preferably 70 mass% or less. As for the amount of solvent used in the cyclization reaction, it is not particularly limited as long as the concentration of the (meth)acrylic polymer in the cyclization reaction solution is within the above range.

[0173] The amount of cyclization catalyst used is preferably 100 ppm or more and 1000 ppm or less relative to the total amount of monomer components constituting the (meth)acrylic polymer, more preferably 110 ppm or more, even more preferably 120 ppm or more, and even more preferably 150 ppm or more, and even more preferably 900 ppm or less, even more preferably 800 ppm or less, and even more preferably 700 ppm or less. By using the cyclization catalyst within the above range, it is possible to obtain a (meth)acrylic resin composition with excellent stability and suppressed silver streaks, while increasing the cyclization rate and forming ring structure units in the (meth)acrylic polymer at a desired ratio.

[0174] As for the method of adding the cyclization catalyst during the cyclization reaction, the entire amount may be added as an initial input, a certain amount may be added as an initial input and the remainder added collectively or continuously into the reaction system during the cyclization reaction, or the entire amount may be introduced into the reaction system by addition. The above continuous addition may be continuous or intermittent, such as divided addition, but it is preferable to be continuous or intermittent with an interval of 10 minutes or less, and it is more preferable to be continuous.

[0175] The reaction temperature of the cyclization reaction is, for example, 50°C to 300°C, and preferably 70°C to 150°C. The reaction time of the cyclization reaction is, for example, about 5 minutes to 6 hours, and preferably 30 minutes to 3 hours.

[0176] According to the cyclization catalyst of the present invention, since the cyclization reaction can be carried out efficiently, even if the reaction time is less than 3 hours, the cyclization rate is high and cyclization within the range of the content ratio of the aforementioned ring structure unit in the (meth)acrylic polymer can be achieved.

[0177] The cyclization reaction is carried out in a reaction vessel for polymerization, and it is also desirable to carry out the cyclization reaction in an autoclave or a multi-tube heat exchanger.

[0178] After the oxidization process, it is desirable to perform post-treatment including a devitrification process.

[0179] The devaporization process refers to a treatment process for removing volatile components such as solvents and residual monomers, as well as alcohol produced as a byproduct by the aforementioned cyclization reaction. Additionally, C phosphoric acid is used as a cyclization catalyst. 3-12 Alkyl ester, C phosphoric acid 3-12 Alkyl esters and C hypophosphorus 3-12 If at least one selected from the group consisting of alkyl esters is used, it is easy to volatilize and remove during the degassing process. Additionally, by performing the degassing process under heating conditions, the cyclization catalyst decomposes to produce alcohol, but it is desirable that the alcohol is also removed.

[0180] If devaporization is insufficient, there is a large amount of residual volatile matter in the (meth)acrylic resin composition, and foaming occurs during molding, resulting in molding defects.

[0181] In addition, when an alkyl phosphate ester, an alkyl phosphite ester, or an alkyl hypophosphite ester with 13 or more carbon atoms is used as a cyclization catalyst, the higher alcohol (alcohol with 13 or more carbon atoms) generated by the decomposition of these compounds is difficult to volatilize and remains in the (meth)acrylic resin composition, thereby reducing the adhesion of the (meth)acrylic resin composition.

[0182] The device used for degassing is not particularly limited, but, for example, an autoclave, a spool-type reactor, a device including a heat exchanger and a degassing tank, an extruder equipped with a vent, etc., may be used, and a dryer may also be used.

[0183] When using an extruder equipped with a vent for degassing, it is preferable that the extruder has a cylinder and a screw provided within the cylinder, and is equipped with a heating means. It is preferable that one or more vents be provided in the cylinder, and it is more preferable that the vents be provided at least downstream of the raw material input section with respect to the conveying direction within the extruder, and they may also be provided upstream of the raw material input section. Degassing proceeds as the polymer supplied into the extruder is conveyed from the upstream side to the downstream side of the extruder while being mixed by the screw. It is preferable that a die be provided downstream of the extruder, and the polymer can be molded into a predetermined shape by extruding it from the die. For example, pellets can be manufactured by finely cutting a polymer molded into a rod shape. In addition, it is preferable that a polymer filter be provided in the die section of the extruder.

[0184] The devolvulation treatment temperature is preferably in the range of 150°C to 350°C, and more preferably in the range of 200°C to 300°C. If the devolvulation treatment temperature is lower than 150°C, there is a problem that devolvulation is insufficient and the amount of residual volatile matter increases; if it is higher than 350°C, it is not desirable because there is a problem that discoloration or decomposition occurs. The pressure reduction during the devolvulation treatment is preferably 13.3 hPa or higher (for example, about 13.3 hPa to 800 hPa).

[0185] In one or more processes selected from the above polymerization process, the above cyclization process, and the process after the above cyclization process, the above additive may be added. However, as an additive, it is preferable not to include the above hindered phenol compound and / or a compound that is a source of the above hindered phenol compound.

[0186] 3. Molded body

[0187] The (meth)acrylic resin composition can be molded into various shapes and used as various products or parts. The shape of the molded body can be appropriately set according to the application, and examples include plate-shaped, granular, powder-shaped, bulk-shaped, particle aggregate-shaped, spherical, elliptical-spherical, lens-shaped, cubic-shaped, columnar, rod-shaped, awl-shaped, tube-shaped, needle-shaped, fibrous, hollow fiber-shaped, porous-shaped, etc. Molded bodies of these (meth)acrylic resin compositions can be manufactured by a process involving the thermal melting of (meth)acrylic resin particles, such as injection molding, extrusion molding, or blow molding, for example, or by further performing secondary molding (vacuum molding, compression molding, etc.) on the primary molded body. As for the shape of the (meth)acrylic resin particles, it is preferable that they be, for example, powders with a particle diameter of 1 μm to 1000 μm, pellets such as cylindrical or spherical shapes with an elongation diameter of about 1 mm to 10 mm, or a mixture thereof.

[0188] The above (meth)acrylic resin particles may also be molded into a film to form an optical film. The optical film is, for example, a polarizer protection film, a phase difference film, a viewing angle compensation film, a light diffusion film, a reflective film, an anti-reflection film, an anti-glare film, a brightness enhancement film, and a conductive film for a touch panel.

[0189] These optical films generally have a (meth)acrylic resin layer comprising a (meth)acrylic resin composition and a primer layer provided on the surface of the (meth)acrylic resin layer, wherein the primer layer comprises particles.

[0190] The primer layer is a layer comprising at least one resin selected from, for example, urethane resin, cellulose resin, polyol resin, polycarboxylic acid resin, and polyester resin.

[0191] The particles may be organic or inorganic particles. Organic particles are particles containing organic polymers, such as (meth)acrylic polymers having (meth)acrylic monomers as constituent units, or styrene polymers having styrene monomers as constituent units. The constituent units of the organic polymers (such as (meth)acrylic monomers or styrene monomers) may be prepared through recycling, such as chemical recycling. Inorganic particles are, for example, silica particles, alumina particles, titania particles, zirconia particles, glassy particles, etc. These particles may also be prepared through recycling.

[0192] The molding temperature of the (meth)acrylic resin composition is not particularly limited, but is preferably in the range of 150°C to 350°C, and more preferably in the range of 200°C to 300°C.

[0193] The (meth)acrylic resin composition of the present invention can reduce roll contamination and, furthermore, suppress the occurrence of silver streaks and has excellent stability, so molded articles using the (meth)acrylic resin composition have excellent appearance and can also be produced with high efficiency.

[0194] The present application claims the benefit of priority based on Japanese Patent Application No. 2022-004679 filed on January 14, 2022. The full contents of the specification of Japanese Patent Application No. 2022-004679 filed on January 14, 2022 are incorporated herein by reference.

[0195] Examples

[0196] The present invention will be explained more specifically below with reference to experimental examples, but the present invention is, of course, not limited by the following experimental examples. It is, of course, possible to implement the invention by making appropriate modifications within the scope suitable for the purpose described above and below, and all such modifications are included within the technical scope of the present invention. Furthermore, in the following experimental examples, unless otherwise specified, "part" means "parts by mass," "ppm" means "ppm by mass," and "%" means "% by mass."

[0197] First, the measurement method employed in the following experimental examples will be explained.

[0198] (1) Weight-average molecular weight, number-average molecular weight, molecular weight distribution

[0199] The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the (meth)acrylic resin in the polymerization solution and after polymerization were determined by polystyrene conversion using gel permeation chromatography (GPC). The apparatus and measurement conditions used for the measurement are as follows.

[0200] Measurement System: Dosoje GPC System HLC-8220

[0201] Measurement side column configuration:

[0202] · Guard Column (Doso, TSK guardcolumn SuperHZ-L)

[0203] · Separation column (Dosoje, TSK Gel Super HZM-M), 2 connected in series

[0204] Reference-side column composition:

[0205] · Reference Column (Dosoje, TSK gel SuperH-RC)

[0206] Developing solvent: Chloroform (Wako Junyaku High School product, Special Grade)

[0207] Developing solvent flow rate: 0.6 mL / min

[0208] Standard Sample: TSK Standard Polystyrene (Polystyrene, PS-Oligomer Kit)

[0209] (2) Turnover rate

[0210] The conversion rate (polymerization rate) (mass%) during the polymerization reaction was calculated by measuring the concentration (mass%) of unreacted monomers in the obtained polymerization solution using gas chromatography (manufactured by Shimadzu Seisakusho Co., Ltd., apparatus name: GC17A) and using Equation (A).

[0211] Conversion rate (polymerization rate) = 100 × (1 - M1 / M0) … (A)

[0212] In the formula, M1 represents the concentration of unreacted monomer in the polymerization solution (mass%), and M0 represents the concentration of monomer in the input raw material solution (mass%).

[0213] (3) Glass transition temperature

[0214] The glass transition temperature (Tg) of the (meth)acrylic resin composition was determined by the point-of-view method in accordance with the specifications of JIS K7121. Specifically, using a differential scanning calorimeter (Thermo plus EVO DSC-8230 manufactured by Rigaku Co., Ltd.), it was evaluated from a DSC curve obtained by heating approximately 10 mg of the sample from room temperature to 200°C (heating rate 20°C / min) under a nitrogen gas flow (100 ml / min). α-alumina was used as a reference.

[0215] (4) Lactone conversion rate

[0216] Two parts of a (meth)acrylic resin composition were dissolved in 20 parts of chloroform, and the resulting solution was added dropwise to 200 parts of methanol to obtain a solution containing a precipitate. The solution containing the precipitate was filtered, the precipitate was extracted, and the sample was obtained by drying it in a vacuum dryer at 80°C for 4 hours. The obtained sample was analyzed by the following method (dynamic TG method), and the lactone reduction rate (%) was calculated from Equation (B).

[0217] Measuring device: Differential parallax thermobalance (Manufactured by Rigaku Co., Ltd., ThermoPlus2 TG-8120, Dynamic TG)

[0218] Measurement conditions: Sample amount 10 mg

[0219] Heating rate: 10℃ / min

[0220] Atmosphere: Nitrogen flow 400 mL / min

[0221] Method: Temperature increase using stepwise isothermal control (controlling the mass loss rate to 0.005% / sec or less within the range of 60°C to 400°C).

[0222] Lactone exchange rate = 1 - (X / Y) … (B)

[0223] In Equation (B), X represents the mass loss rate (mass%) in the dealolysis reaction from 150°C, before mass loss begins, to 300°C, where the decomposition of the polymer begins, and Y represents the theoretical mass loss rate (i.e., the weight loss rate calculated by assuming that 100% of the dealolysis reaction that can occur in the polymer composition has occurred; mass%) assuming that all hydroxyl groups in the polymer composition are dealolyed (lactone cyclized). For example, in the case of the polymers obtained in the examples and comparative examples, the molecular weight of methanol generated by the lactone cyclization reaction is 32, the molecular weight of 2-(hydroxymethyl)methyl acrylate is 116, and the composition ratio of the polymer before lactone cyclization is 12 mass%, so the theoretical mass loss rate Y is (32 / 116)×12=3.31 mass%.

[0224] (5) Phosphorus atomic content

[0225] For a sample solution in which 0.2 parts of a (meth)acrylic resin composition were dissolved in 99.8 parts of 2-butanone, the phosphorus atomic content (ppm) in the (meth)acrylic resin composition was measured using an ICP emission spectroscopic analyzer (Thermo Fisher Scientific, iCAP6500 Duo).

[0226] (6) Measurement of alcohol content

[0227] Sample preparation: 2 parts of a (meth)acrylic resin composition were dissolved in 20 parts of chloroform, and the resulting solution was added dropwise to 200 parts of methanol to obtain a solution containing a precipitate. The solution containing the precipitate was filtered, the methanol-soluble component was extracted, and the sample obtained by drying was dissolved in acetone to obtain a sample solution.

[0228] Measurement: The obtained sample solution was measured using GC-MS, and alcohol components other than methanol were identified. In addition, the sample solution was measured using gas chromatography (manufactured by Shimadzu Seisakusho, device name: GC17A), and the content of alcohol components other than methanol (ppm) in the (meth)acrylic resin composition was quantified.

[0229] (7) Adhesion evaluation

[0230] A (mat)acrylic resin composition was sandwiched between aluminum foils (manufactured by Nippon Test Panel, film thickness 0.1 mm), and also sandwiched between SUS plates from above the aluminum foils. Using a manual heating press (manufactured by Imoto Seisakusho Co., Ltd., IMC-180C type), the composition was melt-press molded at 250°C for 5 minutes. Afterward, the composition was removed from the press while sandwiched between the SUS plates and cooled for 1 minute. When the aluminum foils were peeled off, the adhesion was judged as "good" if the resin composition adhered to the entire surface of the aluminum foils, "average" if the resin composition adhered to only a portion, and "poor" if the composition did not adhere and the foils were peeled off.

[0231] (8) Roll contamination evaluation

[0232] For a (meth)acrylic resin composition, roll contamination was evaluated by performing open film formation.

[0233] Specifically, it was unveiled in the following order.

[0234] A molten film was formed using a vented single-screw extruder equipped with a barrier flight type screw with a diameter of 65 mm and an L / D ratio of 32. The temperature of the extruder cylinder and gear pump was set to 275°C, and the temperature of the polymer filter and T-die was set to 270°C. Pellet containing a (meth)acrylic resin composition was heated to 65°C by blowing heated dehumidified air into the hopper. Additionally, a nitrogen inlet pipe was provided at the bottom of the hopper, and nitrogen gas was introduced into the extruder. While suctioning from the vent port at 25 Torr, the pellet was melted by the single-screw and passed through a leaf disc type polymer filter with a filtration precision of 5 μm using a gear pump. Subsequently, the molten resin was extruded from a T-die with a width of 600 mm and cast onto a cooling roll of hard chrome plating temperature-controlled to 115°C to obtain a raw film with a thickness of 145 μm.

[0235] After the above melt film formation, the surface of the cast cooling roll was visually observed, and it was judged as "Good" if no cloudiness was confirmed, "Average" if cloudiness was confirmed only at the edges in the width direction of the film, and "Poor" if cloudiness was confirmed also in the center in the width direction of the film.

[0236] (9) Foaming evaluation

[0237] A (meth)acrylic resin composition dried in a vacuum dryer at 100°C for 4 hours was filled into a cylinder specified in JIS-K7210, maintained at 280°C (a temperature intended for molding processing) for 20 minutes, and then extruded into a strand. The presence of a silver streak between the upper and lower marks of the obtained strand was visually checked. "×" was used when the occurrence of a silver streak was confirmed, and "○" was used when it was not confirmed.

[0238] Example 1

[0239] 83.5 parts of methyl methacrylate (MMA), 12 parts of 2-(hydroxymethyl)acrylate (MHMA; also known as α-(hydroxymethyl)acrylate), and 88.7 parts of toluene were added to a reaction vessel equipped with a stirring device, a temperature sensor, a cooling condenser, and a nitrogen inlet tube, and the temperature was raised to 105°C while passing nitrogen through it. At the point when reflux accompanying the temperature increase began, 0.535 parts of a 20 wt% toluene solution of t-amylperoxyisononanoate (manufactured by Yoshitomi Arkema Co., Ltd., Luperox (registered trademark) 570T20) were added as a polymerization initiator. Subsequently, a solution containing 4.5 parts of styrene (St) and 0.15 parts of n-dodecyl mercaptan (nDM) was added dropwise over a period of 2 hours. In addition, 1.065 parts of a 20 wt% toluene solution of t-amylperoxyisonanoate were added dropwise over a period of 4 hours. While adding these St, nDM, and t-amylperoxyisonanoate dropwise, the mixture was refluxed at approximately 105 to 110°C, and solution polymerization was carried out. After the addition was finished, aging was performed for an additional 2 hours at the same temperature. The molecular weight (Mw) and conversion rate at the time when polymerization was finished (6 hours after the start of polymerization) were evaluated by taking a portion of the polymerization solution, and were 157,000 and 91.3 mass%, respectively.

[0240] Next, 0.0312 parts of butyl phosphate (manufactured by SC Yuki Chemical Co., Ltd., Phoslex A-4) were added to the obtained polymerization solution as a catalyst for the cyclic condensation reaction (cyclic catalyst), and a cyclic condensation reaction to form a lactone ring structure was carried out for 2 hours under reflux at approximately 90 to 110°C. In addition, the obtained polymerization solution was passed through a multi-tube heat exchanger heated to 235°C to complete the cyclic condensation reaction.

[0241] Afterwards, using a vent-type screw twin extruder (L / D=52.5), the obtained polymerization solution was introduced at a processing speed of 100 parts / hour in terms of resin volume and degassing treatment was performed. The extruder is equipped with one rear vent, four pore vents (hereinafter referred to as the first, second, third, and fourth vents from the upstream side), and a side feeder between the third vent and the fourth vent, and the rotational speed was set to 80 rpm, the pressure reduction to 25 to 800 hPa, and the barrel temperature to 255°C (heated with a heat medium of 255°C). In addition, a leaf disc-type polymer filter (filtration precision 10 μm) is disposed at the tip of the extruder, and in the extrusion die provided at the tip of the polymer filter, a plurality of pores are formed through the circumference of the resin discharge surface, and a watering cut type cutter is installed. In addition, after cutting and water-cooling solidification, a dehydration facility using a centrifugal dryer is provided, and the structure is configured to be returned to a storage silo by gaseous transport.

[0242] When introducing the polymerization solution, ion exchange water was introduced from the upstream of the second and third vents at an inflow rate of 1.5 parts / hour, and ion exchange water was introduced from the upstream of the fourth vent at an inflow rate of 3 parts / hour.

[0243] After the degassing process is finished, the molten (meth)acrylic resin composition is passed through a leaf disc-type polymer filter (filtration precision: 10 μm), then extruded from the die (pores) of the extrusion die, cut, and solidified by water cooling, followed by dehydration by a centrifugal dryer, return, and cooling to a storage silo to obtain a (meth)acrylic resin composition (A-1). The formulation of the obtained (meth)acrylic resin composition (A-1) is shown in Table 1, and each physical property is shown in Table 2.

[0244] Example 2

[0245] A (meth)acrylic resin composition (A-2) was obtained in the same manner as in Example 1, except that 0.0468 parts of butyl phosphate (manufactured by SC Yuki Chemical Co., Ltd., Phoslex A-4) were added as a catalyst for the cyclic condensation reaction (cyclic catalyst). The formulation composition of the obtained (meth)acrylic resin composition (A-2) is shown in Table 1, and each physical property is shown in Table 2.

[0246] Example 3

[0247] A (meth)acrylic resin composition (A-3) was obtained in the same manner as in Example 1, except that 0.0624 parts of butyl phosphate (manufactured by SC Yuki Chemical Co., Ltd., Phoslex A-4) were added as a catalyst for the cyclic condensation reaction (cyclic catalyst). The formulation composition of the obtained (meth)acrylic resin composition (A-3) is shown in Table 1, and each physical property is shown in Table 2.

[0248] Example 4

[0249] After completing the cyclic condensation reaction in the same manner as in Example 2, a degassing treatment was performed using a vent-type screw twin extruder (L / D=52.5). At that time, the procedure was carried out in the same manner as in Example 2, except that a toluene solution containing 35 mass% of a UV absorber (ADEKA Co., Ltd., ADEKA STAP (registered trademark) LA-F70) was fed from the upstream of the third vent at a feeding rate of 1.92 parts / hour, and a (meth)acrylic resin composition (A-4) was obtained. The formulation composition of the obtained (meth)acrylic resin composition (A-4) is shown in Table 1, and each physical property is shown in Table 2.

[0250] Example 5

[0251] A (meth)acrylic resin composition (A-5) was obtained in the same manner as in Example 1, except that 0.0475 parts of octyl phosphate (manufactured by SC Yuki Kagaku Co., Ltd., Phoslex A-8N) were added as a catalyst for the cyclic condensation reaction (cyclic catalyst). The formulation of the obtained (meth)acrylic resin composition (A-5) is shown in Table 1, and each physical property is shown in Table 2.

[0252] Comparative Example 1

[0253] 83.5 parts of MMA, 12 parts of MHMA, 0.07 parts of nDM, and 88.7 parts of toluene were added to a reaction vessel equipped with a stirring device, a temperature sensor, a cooling condenser, and a nitrogen inlet tube, and the temperature was raised to 105°C while passing nitrogen through it. At the point when reflux accompanying the temperature increase began, 0.451 parts of a 20 wt% toluene solution of t-amylperoxyisononanoate (manufactured by Yoshitomi Arkema Co., Ltd., Luperox (registered trademark) 570T20) were added as a polymerization initiator. Subsequently, a solution containing 4.5 parts of St and 0.899 parts of a 20 wt% toluene solution of t-amylperoxyisononanoate was added dropwise over a period of 2 hours. While adding these St and t-amylperoxyiso nanonoates dropwise, the mixture was refluxed at approximately 105 to 110°C, and solution polymerization was carried out. After the addition was finished, aging was performed for an additional 4 hours at the same temperature. The molecular weight (Mw) and conversion rate at the time when polymerization was finished (6 hours after the start of polymerization) were evaluated by taking a portion of the polymerization solution, and were 153,000 and 94.5 mass%, respectively.

[0254] Next, 0.075 parts of stearyl phosphate (S.C. Yuki Chemical Co., Ltd., Phoslex A-18) were added to the obtained polymerization solution as a catalyst for the cyclic condensation reaction (cyclic catalyst), and a cyclic condensation reaction to form a lactone ring structure was carried out for 2 hours under reflux at approximately 90 to 110°C. In addition, the obtained polymerization solution was passed through a multi-tube heat exchanger heated to 235°C, and The condensation reaction was completed.

[0255] Afterwards, using the vent-type screw twin extruder (L / D=52.5) ​​used in Example 1, the obtained polymerization solution was introduced at a processing rate of 100 parts / hour in terms of resin amount, and degassing treatment was performed. When introducing the polymerization solution, ion-exchanged water was introduced from the upstream of the second and fourth vents at an input rate of 1.5 parts / hour, and a toluene solution containing zinc octylate toluene solution (Nihon Kagaku Sangyo Co., Ltd., Nikka Octix Zinc 1.8%):phenolic antioxidant (ADEKA Co., Ltd., Adeka Stab (registered trademark) AO-60):sulfur-based antioxidant (ADEKA Co., Ltd., Adeka Stab (registered trademark) AO-412S) = 33.74:1:1 was introduced from the upstream of the third vent at an input rate of 0.165 parts / hour.

[0256] After the degassing process is finished, the molten (meth)acrylic resin composition is passed through a leaf disc-type polymer filter (filtration precision: 5 μm), then extruded from the die (pores) of the extrusion die, cut, and solidified by water cooling, followed by dehydration by a centrifugal dryer, return, and cooling to a storage silo to obtain a (meth)acrylic resin composition (A-6). The formulation of the obtained (meth)acrylic resin (A-6) composition is shown in Table 1, and each physical property is shown in Table 2.

[0257] Comparative Example 2

[0258] A (meth)acrylic resin composition (A-7) was obtained in the same manner as in Example 1, except that 0.1 part of methyl phosphate (manufactured by SC Yuki Chemical Co., Ltd., Phoslex A-1) was added as a catalyst for the cyclic condensation reaction (cyclic catalyst). The formulation of the obtained (meth)acrylic resin composition (A-7) is shown in Table 1, and each physical property is shown in Table 2.

[0259]

[0260]

[0261] As is evident from Table 2, the (meth)acrylic resin compositions (A-1) to (A-5) obtained in Examples 1 to 5 all received good evaluations regarding adhesion, while the (meth)acrylic resin composition (A-6) obtained in Comparative Example 1 received poor evaluations regarding adhesion. In particular, the (meth)acrylic resin compositions (A-1) to (A-4) obtained using butyl phosphate showed excellent results regarding adhesion.

[0262] In addition, as is evident from Table 2, the (meth)acrylic resin compositions (A-1) to (A-5) obtained in Examples 1 to 5 all showed good evaluations regarding roll contamination, whereas the (meth)acrylic resin composition (A-6) obtained in Comparative Example 1 showed poor evaluations regarding roll contamination. In particular, the (meth)acrylic resin compositions (A-1) to (A-4) obtained using butyl phosphate showed excellent results regarding roll contamination.

[0263] In addition, as is evident from Table 2, the (meth)acrylic resin compositions (A-1) to (A-5) obtained in Examples 1 to 5 all had good evaluations regarding foaming properties, while the (meth)acrylic resin composition (A-7) obtained in Comparative Example 2 had poor evaluations regarding foaming properties.

Claims

Claim 1 A (meth)acrylic resin composition comprising a (meth)acrylic polymer having a ring structure in the main chain that is at least one of a lactone ring structure and a glutaric anhydride structure, wherein the content of phosphorus atoms in the (meth)acrylic resin composition is 1.0 ppm or more and 50 ppm or less, the cyclization rate in the (meth)acrylic polymer is 96.5 mass% or more and 100 mass% or less, and the content of a compound represented by the following formula (I) in the (meth)acrylic resin composition is 95 ppm or less. [Equation (I), R 1 represents an aliphatic hydrocarbon group with 13 or more carbon atoms, or an aromatic hydrocarbon group with 6 or more carbon atoms. Claim 2 A (meth)acrylic resin composition according to claim 1, wherein the content of a compound represented by the following formula (II) in the (meth)acrylic resin composition is 95 ppm or less. [In Equation (II), R 2 represents an aliphatic hydrocarbon group with 3 to 12 carbon atoms. Claim 3 A (meth)acrylic resin composition according to claim 1, wherein the content ratio of ring structure units in the (meth)acrylic polymer having a ring structure is 5 mass% or more and 70 mass% or less. Claim 4 A (meth)acrylic resin composition according to claim 1, wherein the content of a (meth)acrylic polymer having a ring structure in the (meth)acrylic resin composition is 50 mass% or more. Claim 5 A (meth)acrylic resin composition according to claim 1, having a glass transition temperature of 120°C or higher. Claim 6 A (meth)acrylic resin composition according to claim 1, which does not contain hindered phenol compounds. Claim 7 A (meth)acrylic resin composition according to claim 1, which does not contain an organic phosphorus compound having a hindered phenolic group. Claim 8 A molded article comprising a (meth)acrylic resin composition as described in any one of claims 1 to 7. Claim 9 In paragraph 8, a molded body that is a sheet, film, or lens-shaped. Claim 10 A method for preparing a (meth)acrylic resin composition comprising a cyclization process in which, in a (meth)acrylic polymer, at least one of the following cyclization reactions (i) and (ii) is performed to form a ring structure in the main chain of the (meth)acrylic polymer, wherein (i) a cyclization reaction forming a lactone ring structure between a hydroxyl group and an ester group or a carboxyl group; (ii) a cyclization reaction forming a glutaric anhydride structure between a carboxyl group and an ester group or another carboxyl group; wherein, in the cyclization reaction, C phosphoric acid 3-7 Alkyl ester, C phosphoric acid 3-7 Alkyl esters and C hypophosphorus 3-7 A method for preparing a (meth)acrylic resin composition characterized by using at least one selected from the group consisting of alkyl esters as a catalyst. Claim 11 A method for preparing a (meth)acrylic resin composition according to claim 10, wherein the catalyst used in the above cyclization reaction is at least one selected from the group consisting of butyl phosphate, butyl phosphite, and butyl hypophosphite. Claim 12 A method for manufacturing a (meth)acrylic resin composition according to claim 10, wherein the amount of the catalyst used is 1000 ppm or less relative to the total amount of monomer components constituting the (meth)acrylic polymer. Claim 13 A method for manufacturing a (meth)acrylic resin composition according to claim 10, wherein the decomposition temperature of the catalyst is 160°C or higher. Claim 14 A method for manufacturing a (meth)acrylic resin composition, wherein, in any one of claims 10 to 13, the polymerization process further comprises polymerizing a (meth)acrylic monomer to form the (meth)acrylic polymer. Claim 15 A method for preparing a (meth)acrylic resin composition according to claim 14, wherein the total content ratio of constituent units derived from the (meth)acrylic monomer in all constituent units of the (meth)acrylic polymer is 50 mass% or more. Claim 16 A method for preparing a (meth)acrylic resin composition according to claim 14, wherein the (meth)acrylic monomer is α-(1-hydroxyalkyl)alkyl acrylate, and the total content ratio of constituent units derived from α-(1-hydroxyalkyl)alkyl acrylate in the total constituent units of the (meth)acrylic polymer is 5 mass% or more. Claim 17 A method for preparing a (meth)acrylic resin composition according to claim 14, wherein an additive is added in one or more processes selected from the polymerization process, the cyclization process, and the process after the cyclization process, and the additive does not include hindered phenol compounds and organic phosphorus compounds having hindered phenol groups. Claim 18 delete

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