Plasticizer and thermoplastic resin composition

Abstract

The plasticizer contains a (meth)acrylic polymer having a weight average molecular weight of 3,000 or less. The (meth)acrylic polymer includes a structural unit (U1) derived from a (meth)acrylic acid alkyl ester having an alkyl group having 9 or fewer carbon atoms in the ester moiety and a structural unit (U2) derived from a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms in the ester moiety, and has a glass transition temperature of -75°C or less.

Description

Plasticizer and thermoplastic resin composition

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to Japanese Patent Application No. 2024-105758, filed on June 28, 2024, the entire contents of which are incorporated herein by reference. The present disclosure relates to a plasticizer and a thermoplastic resin composition.

[0002] Plasticizers are commonly used to soften thermoplastic resins such as vinyl chloride resins and ABS resins. Furthermore, among products manufactured using thermoplastic resins, excellent flexibility, heat resistance, and weather resistance are often required for wire coatings, building components, agricultural materials, sheets and films used outdoors, and sheets, films, and leathers used inside or outside automobiles. However, resin compositions containing phthalate esters, trimellitate esters, polyesters, and polyethers, which have been widely used as plasticizers, together with thermoplastic resins have shown insufficient weather resistance and heat resistance. Specifically, when low-molecular-weight compounds such as phthalate esters and trimellitate esters are used as plasticizers, the plasticizers are easily released from the resin composition over time, which can lead to a loss of flexibility and the resulting cracks in the product. Furthermore, when high-molecular-weight compounds such as polyesters and polyethers are used as plasticizers, the plasticizers in the resin composition decompose over time, resulting in the release of decomposition products from the resin composition, which can prevent the resin composition from maintaining its weather resistance over a long period of time.

[0003] Therefore, it has been proposed to use a relatively low molecular weight (meth)acrylic polymer as a plasticizer (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses the use of an acrylic polymer obtained by polymerizing monomers at a temperature of 180 to 350°C for 5 to 60 minutes as a plasticizer. Patent Document 2 discloses the use of a copolymer of an alkoxyalkyl (meth)acrylate and another monomer as a plasticizer.

[0004] International Publication No. WO 2001 / 83619 International Publication No. WO 2002 / 100943

[0005] It has been confirmed that resin products using the (meth)acrylic polymers disclosed in Patent Documents 1 and 2 as a plasticizer are brittle in low-temperature environments (e.g., −20° C.) and are prone to breakage when subjected to impact in low-temperature environments. Furthermore, the inventors have conducted studies and found that the resin products become hard when stored for a long period of time in a high-temperature environment, for example, at 100° C., and are prone to deterioration in mechanical properties, as well as to change in color (browning or blackening).

[0006] The present disclosure has been made in view of the above circumstances, and one object of the present disclosure is to provide a plasticizer that can give a thermoplastic resin composition that is excellent in flexibility, cold resistance, and heat resistance.

[0007] According to the present disclosure, the following plasticizer and thermoplastic resin composition are provided.

[0008] [1] A plasticizer comprising a (meth)acrylic polymer having a weight-average molecular weight of 3,000 or less, the (meth)acrylic polymer comprising a structural unit (U1) derived from a (meth)acrylic acid alkyl ester having an alkyl group containing 9 or less carbon atoms in the ester moiety and a structural unit (U2) derived from a (meth)acrylic acid alkyl ester having an alkyl group containing 10 or more carbon atoms in the ester moiety, and having a glass transition temperature of -75°C or less. [2] The plasticizer according to [1], wherein the content of the structural unit (U2) is 1 to 50 mass% relative to the total amount of structural units derived from monomers constituting the (meth)acrylic polymer. [3] The plasticizer according to [1] or [2], wherein the SP value is 9.30 or more. [4] The plasticizer according to any one of [1] to [3], wherein the content of carbon-carbon double bonds in the (meth)acrylic polymer is 0.01 to 0.50 meq / g. [5] The plasticizer according to any one of [1] to [4], wherein the content of structural units derived from a (meth)acrylic acid alkyl ester is 90 mass% or more relative to the total amount of structural units derived from monomers constituting the (meth)acrylic polymer. [6] The plasticizer according to any one of [1] to [5], which is used for plasticizing a vinyl chloride resin. [7] A thermoplastic resin composition containing the plasticizer according to any one of [1] to [6] and a thermoplastic resin.

[0009] According to the plasticizer of the present disclosure, a thermoplastic resin composition having excellent flexibility, cold resistance, and heat resistance can be obtained.

[0010] The present disclosure will be described in detail below. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, "(meth)acrylate" means acrylate and / or methacrylate, and "(meth)acrylo" means acrylo and / or methacrylo.

[0011] <Plasticizer> The plasticizer of the present disclosure contains a (meth)acrylic polymer (hereinafter also referred to as "(meth)acrylic polymer (P)") having a weight-average molecular weight of 3,000 or less. The (meth)acrylic polymer (P) contains structural units derived from a (meth)acrylic acid alkyl ester. The (meth)acrylic polymer (P) also contains, as structural units derived from a (meth)acrylic acid alkyl ester, structural units having an alkyl group having 9 or less carbon atoms in the ester moiety and structural units having an alkyl group having 10 or more carbon atoms in the ester moiety. Hereinafter, first, the physical properties of the (meth)acrylic polymer (P) will be described, and then the structural units contained in the (meth)acrylic polymer (P) will be described.

[0012] <Physical Properties of (Meth)acrylic Polymer (P)> (Molecular Weight Characteristics) The weight-average molecular weight of the (meth)acrylic polymer (P) is 3,000 or less. If the weight-average molecular weight (Mw) of the (meth)acrylic polymer (P) exceeds 3,000, the cold resistance of the thermoplastic resin composition containing the thermoplastic resin and the (meth)acrylic polymer (P) may not be sufficiently ensured. From the viewpoint of obtaining a resin composition with sufficiently high cold resistance, the Mw of the (meth)acrylic polymer (P) is preferably 2,500 or less, more preferably 2,000 or less, even more preferably 1,800 or less, and even more preferably 1,650 or less. The lower limit of the Mw of the (meth)acrylic polymer (P) is not particularly limited, but from the viewpoint of suppressing volatilization of the plasticizer during heat molding of the thermoplastic resin and from the viewpoint of obtaining a resin composition with good weather resistance, it is preferably 500 or more, more preferably 600 or more, and even more preferably 1,000 or more.

[0013] The number average molecular weight (Mn) of the (meth)acrylic polymer (P) is preferably 2,500 or less, more preferably 2,000 or less, even more preferably 1,800 or less, and even more preferably 1,500 or less. The lower limit of Mn of the (meth)acrylic polymer (P) is, for example, 500 or more, preferably 600 or more, and more preferably 750 or more. In this specification, the molecular weight of the polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0014] The molecular weight distribution (Mw / Mn) of the (meth)acrylic polymer (P), which is the ratio of Mw to Mn, is preferably 1.60 or less, and more preferably 1.50 or less, from the viewpoint of enhancing the effect of plasticizing the thermoplastic resin. The lower limit of Mw / Mn of the (meth)acrylic polymer (P) is not particularly limited, and can be 1.0 or more.

[0015] (Glass Transition Temperature) The glass transition temperature (Tg) of the (meth)acrylic polymer (P) is −75° C. or lower. If the glass transition temperature of the (meth)acrylic polymer (P) is higher than −75° C., when a thermoplastic resin composition is produced by blending the (meth)acrylic polymer (P), the cold resistance of the thermoplastic resin composition tends to be insufficient. From the viewpoint of obtaining a thermoplastic resin composition that is excellent in heat resistance in addition to cold resistance, the Tg of the (meth)acrylic polymer (P) is preferably −78° C. or lower, more preferably −79° C. or lower, and even more preferably −80° C. or lower. The lower limit of the Tg of the (meth)acrylic polymer (P) is not particularly limited, but from the viewpoint of easy availability of raw materials, it is, for example, −90° C. or higher. In this specification, the Tg of the polymer is a value obtained using a differential scanning calorimeter (DSC) at a heating rate of 10° C. / min in a nitrogen atmosphere. Details of the measurement conditions are as described in the Examples below.

[0016] (SP Value) The (meth)acrylic polymer (P) preferably has an SP value, which is a solubility parameter, of 9.30 or more. When the SP value of the (meth)acrylic polymer (P) is 9.30 or more, the compatibility of the (meth)acrylic polymer (P) with thermoplastic resins can be further improved. From the viewpoints of improving the compatibility of the (meth)acrylic polymer (P) with thermoplastic resins, imparting sufficient flexibility to the thermoplastic resin composition, and improving the heat resistance and cold resistance of the thermoplastic resin composition, the SP value of the (meth)acrylic polymer (P) is preferably 9.32 or more, more preferably 9.35 or more, even more preferably 9.38 or more, and even more preferably 9.50 or more. There are no particular restrictions on the upper limit of the SP value of the (meth)acrylic polymer (P), but from the viewpoint of improving compatibility with thermoplastic resins, it is, for example, 11.0 or less, or may be 10.0 or less, or may be 9.80 or less.

[0017] In this specification, the SP value of a polymer is a value calculated by the Fedors method (unit: [cal / cm ３ ] １／２ Specifically, the SP value of a polymer can be calculated by the calculation method described in "Polymer Engineering and Science" 14(2), 147 (1974) by R. F. Fedors.

[0018] (Amount of Carbon-Carbon Double Bonds) In the (meth)acrylic polymer (P), at least a portion of the polymers constituting the (meth)acrylic polymer (P) as a molecular aggregate preferably have a carbon-carbon double bond at a terminal thereof. By having a carbon-carbon double bond at at least a portion of the molecular terminal of the (meth)acrylic polymer (P), the compatibility of the (meth)acrylic polymer (P) with thermoplastic resins can be further improved.

[0019] From the viewpoint of sufficiently enhancing the effect of improving the compatibility between the (meth)acrylic polymer (P) and the thermoplastic resin, the content of carbon-carbon double bonds in the (meth)acrylic polymer (P) (hereinafter also referred to as "double bond concentration") is preferably 0.01 meq / g or more, and more preferably 0.02 meq / g or more. With respect to the upper limit of the double bond concentration, from the viewpoint of ensuring the heat resistance and cold resistance of the thermoplastic resin composition blended with the plasticizer, it is preferably 1.20 meq / g or less, more preferably 0.80 meq / g or less, even more preferably 0.50 meq / g or less, and even more preferably 0.40 meq / g or less. In this specification, the double bond concentration of the polymer is 1 It is a value calculated from the amount of double bonds in the polymer determined by H-NMR measurement and the composition of the polymer. Details of the measurement method follow the method described in the Examples below.

[0020] A preferred range of the double bond concentration of the (meth)acrylic polymer (P) can be set by appropriately combining the above-mentioned preferred upper and lower limits of the double bond concentration of the (meth)acrylic polymer (P). Specifically, the range of the double bond concentration of the (meth)acrylic polymer (P) is preferably 0.01 to 1.20 meq / g, more preferably 0.01 to 0.80 meq / g, even more preferably 0.01 to 0.50 meq / g, still more preferably 0.01 to 0.40 meq / g, and even more preferably 0.02 to 0.40 meq / g.

[0021] (Viscosity) From the viewpoint of enhancing the plasticizing effect of the (meth)acrylic polymer (P), the viscosity of the (meth)acrylic polymer (P) is preferably 1,000 mPa s or less, more preferably 600 mPa s or less, and even more preferably 400 mPa s or less. There are no particular restrictions on the lower limit of the viscosity of the (meth)acrylic polymer (P), but from the viewpoint of suppressing bleed-out of the (meth)acrylic polymer (P) in a thermoplastic resin composition containing the (meth)acrylic polymer (P), the viscosity is preferably 80 mPa s or more, more preferably 90 mPa s or more. In this specification, the viscosity of the polymer is a value measured using an E-type viscometer at 25°C.

[0022] It is considered that the introduction of a long-chain alkyl group into the side chain of a (meth)acrylic polymer having a relatively small molecular weight increases the compatibility with the thermoplastic resin, and the side chains are aligned perpendicular to the main chain, causing entanglement of the side chains with each other and the formation of a crystalline structure, which makes it difficult for the (meth)acrylic polymer (P) to be released from the resin composition, resulting in a thermoplastic resin composition having excellent flexibility, cold resistance, and heat resistance.

[0023] In particular, when a carbon-carbon double bond is introduced at the molecular end of the (meth)acrylic polymer (P), the carbon-carbon double bond at the molecular end efficiently functions as a radical scavenger, and as a result, it is thought that the formation of a structure that causes coloration in the thermoplastic resin is effectively suppressed. As a result, it is thought that a plasticizer containing a (meth)acrylic polymer (P) having a carbon-carbon double bond at its molecular end effectively suppresses color change in high-temperature environments while increasing the flexibility of the thermoplastic resin composition, and also enables the thermoplastic resin composition to maintain good flexibility even in low-temperature environments.

[0024] Furthermore, in the production of vinyl chloride resin products, metal soaps such as stearates, which are relatively inexpensive stabilizers, are commonly used as additives. The (meth)acrylic polymer (P) having a long-chain alkyl group introduced therein has good compatibility with these metal soaps, which may contribute to preventing discoloration of the thermoplastic resin composition by increasing the durability of the stabilizer. However, these are merely speculations and do not limit the present invention in any way.

[0025] <Structural Units of (Meth)acrylic Polymer (P)> Next, the structural units contained in the (meth)acrylic polymer (P) will be described. Note that, hereinafter, a structural unit having an alkyl group with 9 or less carbon atoms in the ester moiety will also be referred to as a "structural unit (U1)," and a structural unit having an alkyl group with 10 or more carbon atoms in the ester moiety will also be referred to as a "structural unit (U2)."

[0026] The (meth)acrylic polymer (P) is a polymer mainly composed of a (meth)acrylic acid alkyl ester. The (meth)acrylic acid alkyl ester is represented by the following general formula (1): CH ２ =CR １ -COO-R ２ (1) where R １ is a hydrogen atom or a methyl group. ２ is an alkyl group.

[0027] Specifically, in the (meth)acrylic polymer (P), the content of the structural units derived from the (meth)acrylic acid alkyl ester is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, relative to the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P), from the viewpoint of sufficiently enhancing the plasticizing effect of the (meth)acrylic polymer (P). The content of the structural units derived from the (meth)acrylic acid alkyl ester is equivalent to the total content of the structural units (U1) and (U2).

[0028] Moreover, from the viewpoint of being able to sufficiently lower the glass transition temperature of the (meth)acrylic polymer (P), an acrylic acid alkyl ester can be preferably used as the monomer constituting the (meth)acrylic polymer (P). In the (meth)acrylic polymer (P), the content of structural units derived from the acrylic acid alkyl ester is preferably 40 mass% or more, more preferably 50 mass% or more, even more preferably 60 mass% or more, still more preferably 70 mass% or more, even more preferably 80 mass% or more, and still more preferably 90 mass% or more, relative to the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P).

[0029] Structural Unit (U1) The (meth)acrylic acid alkyl ester constituting the structural unit (U1) is an ester group moiety (i.e., —COO—R ２) has a linear or branched alkyl group having 1 to 9 carbon atoms. Specific examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, and isononyl (meth)acrylate.

[0030] In terms of imparting superior flexibility to the thermoplastic resin composition, the (meth)acrylic acid alkyl ester constituting the structural unit (U1) preferably has an alkyl group having 3 or more carbon atoms, and more preferably has an alkyl group having 3 to 8 carbon atoms.

[0031] Furthermore, in order to sufficiently lower the glass transition temperature of the (meth)acrylic polymer (P), an alkyl acrylate ester having an alkyl group having 6 to 9 carbon atoms may be used as at least a part of the monomers constituting the structural unit (U1). The amount used can be appropriately set depending on the desired glass transition temperature of the polymer. From the viewpoint of ensuring compatibility with the thermoplastic resin, the content of the structural unit derived from the alkyl acrylate ester having an alkyl group having 6 to 9 carbon atoms is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P).

[0032] The content of the structural unit (U1) in the (meth)acrylic polymer (P) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P), from the viewpoint of improving compatibility with the thermoplastic resin. Furthermore, the content of the structural unit (U1) is preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P), from the viewpoint of improving the heat resistance of the thermoplastic resin composition. The monomers constituting the structural unit (U1) may be used singly or in combination of two or more.

[0033] The preferred range of the content of the structural unit (U1) can be set by appropriately combining the above-mentioned preferred upper and lower limits of the content of the structural unit (U1). The range of the content of the structural unit (U1) is preferably 20 to 99 mass%, more preferably 30 to 95 mass%, even more preferably 40 to 90 mass%, still more preferably 50 to 85 mass%, and even more preferably 60 to 80 mass%, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer.

[0034] Structural Unit (U2) Examples of the (meth)acrylic acid alkyl ester constituting the structural unit (U2) include monomers having a linear or branched alkyl group having 10 to 30 carbon atoms in the ester group moiety. Specific examples thereof include n-decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0035] In terms of improving the heat resistance while ensuring the flexibility of the thermoplastic resin composition, the (meth)acrylic acid alkyl ester constituting the structural unit (U2) preferably has an alkyl group having 10 to 20 carbon atoms, more preferably has an alkyl group having 10 to 18 carbon atoms, and even more preferably has an alkyl group having 11 to 18 carbon atoms.

[0036] From the viewpoint of improving the cold resistance and heat resistance in a well-balanced manner while ensuring the flexibility of the thermoplastic resin composition, the content of the structural unit (U2) in the (meth)acrylic polymer (P) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P). Furthermore, the content of the structural unit (U2) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer (P). The monomers constituting the structural unit (U2) may be used singly or in combination of two or more.

[0037] The preferred range of the content of the structural unit (U2) can be set by appropriately combining the above-mentioned preferred upper and lower limits of the content of the structural unit (U2). The range of the content of the structural unit (U2) is preferably 1 to 50 mass%, more preferably 2 to 45 mass%, even more preferably 5 to 45 mass%, even more preferably 10 to 40 mass%, and still more preferably 20 to 40 mass%, based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer.

[0038] (Other Monomers) The (meth)acrylic polymer (P) may be composed only of the structural unit (U1) and the structural unit (U2). The (meth)acrylic polymer (P) may further contain structural units derived from monomers other than the (meth)acrylic acid alkyl ester (hereinafter also referred to as "other monomers") for the purpose of adjusting the glass transition temperature and SP value of the polymer, within a range that does not impair the effects of the present invention.

[0039] The other monomer is not particularly limited as long as it is a monomer copolymerizable with the (meth)acrylic acid alkyl ester. As the other monomer, various vinyl-based monomers can be used, for example, unsaturated carboxylic acid, unsaturated acid anhydride, aliphatic cyclic ester of (meth)acrylic acid, aromatic ester of (meth)acrylic acid, (meth)acrylic acid alkoxyalkyl ester, (meth)acrylic acid hydroxyalkyl ester, polyalkylene glycol mono(meth)acrylate, halogen-containing vinyl compound, vinyl ester compound, vinyl ether compound, heterocyclic ring-containing vinyl compound, amino group-containing vinyl compound, amide group-containing vinyl compound, nitrile group-containing vinyl compound, aromatic vinyl compound, maleimide compound, etc. As the other monomer, one type may be used alone, or two or more types may be used in combination.

[0040] Specific examples of these include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, cinnamic acid, succinic acid monohydroxyethyl (meth)acrylate, ω-carboxy-caprolactone mono(meth)acrylate, β-carboxyethyl (meth)acrylate, 4-carboxystyrene, etc., and unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0041] Examples of aliphatic cyclic esters of (meth)acrylic acid include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, etc. Specific examples of aromatic esters of (meth)acrylic acid include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 3-phenoxypropyl (meth)acrylate, etc.

[0042] Examples of the alkoxyalkyl (meth)acrylate include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, n-propoxybutyl (meth)acrylate, and n-butoxybutyl (meth)acrylate.

[0043] Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the polyalkylene glycol mono(meth)acrylate include polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polyethylene glycol-polypropylene glycol mono(meth)acrylate.

[0044] Examples of halogen-containing vinyl compounds include vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride. Examples of heterocycle-containing vinyl compounds include glycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and (3-ethyloxetan-3-yl)methyl (meth)acrylate. Examples of vinyl ester compounds include vinyl acetate and vinyl propionate. Examples of vinyl ether compounds include methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether.

[0045] Examples of the amino group-containing vinyl compound include dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-(di-n-propylamino)ethyl (meth)acrylate, 2-dimethylaminopropyl (meth)acrylate, 2-diethylaminopropyl (meth)acrylate, 2-(di-n-propylamino)propyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, and 3-(di-n-propylamino)propyl (meth)acrylate.

[0046] Examples of the amide group-containing vinyl compound include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and N-methylol(meth)acrylamide.

[0047] Examples of the nitrile group-containing vinyl compound include cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, 8-cyanooctyl (meth)acrylate, (meth)acrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, and α-fluoroacrylonitrile.

[0048] Examples of aromatic vinyl compounds include styrene, α-methylstyrene, β-methylstyrene, vinylxylene, methylstyrene, ethylstyrene, butylstyrene, methoxystyrene, hydroxystyrene, isopropenylphenol, vinylbenzoic acid, and vinylnaphthalene.

[0049] Examples of the maleimide compound include maleimide and N-substituted maleimide compounds. Examples of the N-substituted maleimide compound include N-alkyl-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, and N-tert-butylmaleimide; N-cycloalkyl-substituted maleimides such as N-cyclopentylmaleimide and N-cyclohexylmaleimide; N-aralkyl-substituted maleimides such as N-benzylmaleimide; and N-aryl-substituted maleimides such as N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-acetylphenyl)maleimide, and N-(4-methoxyphenyl)maleimide.

[0050] From the viewpoint of fully exhibiting the plasticizing effect, it is preferable that the (meth)acrylic polymer (P) is substantially free of structural units having a carboxyl group. Specifically, the content of structural units having a carboxyl group in the (meth)acrylic polymer (P) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and still more preferably 0.5% by mass or less, based on the total structural units of the (meth)acrylic polymer (P).

[0051] <Constituents of Plasticizer> The plasticizer of the present disclosure may be composed of a (meth)acrylic polymer (P), or may further contain a component different from the (meth)acrylic polymer (P) (hereinafter also referred to as "other component"). In the plasticizer of the present disclosure, the content of the (meth)acrylic polymer (P) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, still more preferably 98% by mass or more, and even more preferably 99% by mass or more, relative to the total amount of the plasticizer. The (meth)acrylic polymer (P) blended in the plasticizer may be one type or two or more types.

[0052] Examples of other components to be incorporated into the plasticizer include an oligomer of a (meth)acrylic polymer different from the (meth)acrylic polymer (P) that exhibits a plasticizing effect; a known ester-based or ether-based plasticizer; and the like. Only one type of other component may be used, or two or more types may be used. The content of the other components in the plasticizer of the present disclosure can be appropriately set within a range that does not impair the effects of the present invention.

[0053] <<Method for Producing Plasticizer>> The method for producing the plasticizer of the present disclosure is not particularly limited. The plasticizer of the present disclosure can be produced, for example, by a method including a step of obtaining a (meth)acrylic polymer (P) by polymerizing a monomer (hereinafter also referred to as a “polymerization step”).

[0054] (Polymerization step) The polymerization method for producing the (meth)acrylic polymer (P) is not particularly limited. The (meth)acrylic polymer (P) can be obtained by polymerizing monomers using a known radical polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization. Among these, the solution polymerization method is preferred because it is easy to control the molecular weight and structure of the polymer.

[0055] In the case of solution polymerization, for example, a polymerization solvent and monomers are charged into a reactor, and a polymerization initiator is added to polymerize to obtain a target polymer. When carrying out polymerization, the method of charging each raw material including the monomer may be a batch-type initial lump-sum charging in which all raw materials are charged at once, a semi-continuous charging in which at least a portion of the raw materials are continuously fed into the reactor, or a continuous polymerization method in which all raw materials are continuously fed and at the same time the produced resin is continuously withdrawn from the reactor.

[0056] An example of a preferred polymerization method for obtaining the (meth)acrylic polymer (P) is a method (high-temperature continuous polymerization method) in which raw materials containing monomers, a polymerization solvent, and a polymerization initiator are supplied to a pressurized reactor at a constant supply rate, the raw materials are heated to a high temperature, and polymerization is carried out, and an amount of polymer solution corresponding to the amount of raw materials supplied is withdrawn from the reactor. The high-temperature continuous polymerization method can produce a (meth)acrylic polymer with a low molecular weight and low viscosity. It can also easily produce a (meth)acrylic polymer having a terminal carbon-carbon double bond. Furthermore, when producing a (meth)acrylic polymer using the high-temperature continuous polymerization method, molecular weight control can be suitably performed even when the amount of polymerization initiator or chain transfer agent used is reduced, and the amount of impurities in the plasticizer can be reduced. Therefore, when a mixture of the plasticizer of the present disclosure and a thermoplastic resin is molded, a resin product with excellent heat resistance and cold resistance and high strength can be obtained.

[0057] As the polymerization solvent, an organic solvent can be preferably used. Examples of the organic solvent include cyclic ethers such as tetrahydrofuran and dioxane; chain ethers such as methyl orthoformate and trimethyl orthoacetate; aromatic hydrocarbons such as benzene, toluene, and xylene; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and alcohols such as methanol, ethanol, normal propyl alcohol, isopropyl alcohol, normal butanol, secondary butyl alcohol, isobutyl alcohol, tertiary butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol, 3-methyl-3-pentanol, 1-heptanol, 1-octanol, 2-ethylhexanol, and 3-ethyl-3-hexanol.

[0058] The polymerization solvent preferably contains a primary alcohol. In the polymerization step for obtaining the (meth)acrylic polymer (P), monomers are polymerized in a solvent containing a primary alcohol. The (meth)acrylic polymer (P) obtained by the polymerization is mixed with a thermoplastic resin and molded to obtain a resin product having excellent cold resistance. From the viewpoint of enhancing the effect of improving cold resistance, the primary alcohol used in the polymerization solvent preferably has 4 to 8 carbon atoms, and from the viewpoint of easy availability of raw materials, normal butanol or 2-ethylhexanol is particularly preferred.

[0059] When polymerization is carried out using a primary alcohol as a polymerization solvent, the polymerization solvent may be a solvent consisting solely of a primary alcohol, or may be a mixed solvent of a primary alcohol and a polymerization solvent other than the primary alcohol (hereinafter also referred to as "other solvent"). Examples of other solvents include the organic solvents exemplified above. The amount of primary alcohol used is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total amount of the polymerization solvent.

[0060] The amount of the polymerization solvent used is preferably 5 to 180 parts by mass, more preferably 10 to 150 parts by mass, per 100 parts by mass of the total amount of the monomers. The polymerization solvent may be used alone or in combination of two or more.

[0061] The polymerization initiator is not particularly limited, and known radical polymerization initiators such as organic peroxides, inorganic peroxides, and azo compounds can be used.

[0062] Specific examples of the polymerization initiator include organic peroxides such as di-tert-butyl peroxide, cyclohexanone peroxide, dibenzoyl peroxide, 3,3,5-trimethylcyclohexanone peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, etc. Specific examples of inorganic peroxides include potassium persulfate, sodium persulfate, etc.

[0063] Examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2-(tert-butylazo)-2-cyanopropane, 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), and dimethyl 2,2'-azobis(2-methylpropionate).

[0064] Furthermore, as the polymerization initiator, a redox type polymerization initiator comprising a known oxidizing agent and a known reducing agent may be used. Examples of redox type polymerization initiators include those using sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, ferrous sulfate, or the like as a reducing agent, and potassium peroxodisulfate, hydrogen peroxide, tert-butyl hydroperoxide, or the like as an oxidizing agent. Furthermore, a known chain transfer agent can also be used in combination with the polymerization initiator. When producing the (meth)acrylic polymer (P), among the above, organic peroxides can be preferably used as the polymerization initiator because they allow for easy control of the molecular weight within the desired range.

[0065] In producing the (meth)acrylic polymer (P), the amount of the polymerization initiator used is, for example, 0.01 to 20 parts by mass, and preferably 0.05 to 15 parts by mass, per 100 parts by mass of the total amount of the monomers used in the polymerization.

[0066] From the viewpoints of controlling the molecular weight of the (meth)acrylic polymer (P) within the above range and suppressing coloration of the reaction solution due to the progress of the decomposition reaction, it is preferable to carry out the polymerization at a high temperature. Specifically, the polymerization temperature is preferably in the range of 180°C or higher and 350°C or lower. From the above viewpoints, the polymerization temperature is more preferably 200°C or higher, even more preferably 210°C or higher, and even more preferably 220°C or higher. The upper limit of the polymerization temperature is more preferably 330°C or lower, even more preferably 310°C or lower, and even more preferably 290°C or lower.

[0067] When polymerization is carried out by the high-temperature continuous polymerization method, the residence time of the raw materials is, for example, 2 to 60 minutes. The pressure during polymerization may be any pressure that can maintain the polymerization temperature.

[0068] Other embodiments of the synthesis method for the (meth)acrylic polymer (P) include, for example, the bulk polymerization methods described in JP-A-57-502171, JP-A-59-6207, JP-A-60-215007, etc. Furthermore, the product obtained by bulk polymerization can be treated with a thin-film evaporator or the like to remove volatile components from the product, and further treated with a purification apparatus such as that described in JP-A-2009-221265 to reduce the amount of low-molecular-weight components in the product. This allows for the production of a (meth)acrylic polymer (P) with higher purity.

[0069] If the polymer obtained by the polymerization contains sulfur atoms derived from compounds having sulfur atoms, such as mercaptans, this can cause a decrease in the weather resistance and tensile properties of the polymer. Therefore, it is preferable that the sulfur atom content in the (meth)acrylic polymer (P) is as low as possible. Specifically, the sulfur atom content in the (meth)acrylic polymer (P) is preferably 0 ppm or more and less than 1000 ppm, more preferably 0 ppm or more and less than 100 ppm, even more preferably 0 ppm or more and less than 10 ppm, and even more preferably 0 ppm or more and less than 1 ppm. In this specification, the "sulfur atom content" refers to the total amount of sulfur atoms contained in the polymer, and can be quantified by ICP atomic emission spectroscopy.

[0070] Phosphorus atoms derived from phosphorus compounds and the like also cause a decrease in the weather resistance and tensile properties of the polymer. Therefore, it is preferable that the phosphorus atom content in the (meth)acrylic polymer (P) is as small as possible. Specifically, the phosphorus atom content in the (meth)acrylic polymer (P) is preferably 0 ppm or more and less than 1000 ppm, more preferably 0 ppm or more and less than 100 ppm, even more preferably 0 ppm or more and less than 10 ppm, and even more preferably 0 ppm or more and less than 1 ppm. In this specification, the "phosphorus atom content" refers to the total amount of phosphorus atoms contained in the polymer, and can be quantified by ICP atomic emission spectroscopy.

[0071] Metal atoms derived from metal complex compounds, etc., can also cause a decrease in the weather resistance and tensile properties of the polymer, and can also cause discoloration. Therefore, it is preferable that the metal atom content in the (meth)acrylic polymer (P) be as low as possible. Specifically, the metal atom content in the (meth)acrylic polymer (P) is preferably 0 ppm or more and less than 1000 ppm, more preferably 0 ppm or more and less than 100 ppm, even more preferably 0 ppm or more and less than 10 ppm, and even more preferably 0 ppm or more and less than 1 ppm. In this specification, the "metal atom content" refers to the total amount of metal atoms contained in the polymer, and can be quantified by ICP atomic emission spectroscopy. Note that metal complex compounds include metal complex compounds used as chain transfer agents, as well as metals present in the monomers, polymerization initiators, and polymerization solvents used in the production of the polymer, and metals mixed in from the outside during production. Generally, commercially available monomers, polymerization initiators, and polymerization solvents are purified by distillation, recrystallization, or the like, and therefore the metal atom content of these reagents is less than 2 ppm. However, using unpurified raw materials is not preferred because the metal atom content in the raw materials becomes high.

[0072] Residual volatile components remaining in the (meth)acrylic polymer (P), such as solvents, unreacted monomers, and decomposition products derived from the polymerization initiator, can also cause a decrease in the weather resistance and tensile properties of the polymer. These residual volatile components initially function as plasticizers, but gradually volatilize from the polymer over time, which can cause the polymer to lose its initial tensile properties or emit an odor. Therefore, it is preferable that the amount of residual volatile components in the (meth)acrylic polymer (P) be as small as possible. Specifically, the amount of residual volatile components in the (meth)acrylic polymer (P) is preferably 0.0% or more and less than 2.0%, more preferably 0.0% or more and less than 1.5%, even more preferably 0.0% or more and less than 1.0%, even more preferably 0.0% or more and less than 0.8%, and even more preferably 0.0% or more and less than 0.5%. In this specification, the "amount of residual volatile components" refers to the total amount of residual volatile components contained in the polymer, which can be quantified by gas chromatography.

[0073] The polymer obtained by the polymerization may be subjected to isolation and / or purification treatment in order to remove low-molecular-weight compounds contained in the polymer. When the polymer is isolated and / or purified, these treatments can be carried out using known methods. For example, the isolation and purification of the polymer can be carried out by thin-film distillation, reprecipitation, or the like. The polymer obtained by the polymerization may be used as a plasticizer as is, or may be used as a plasticizer after blending with other components as necessary.

[0074] <<Thermoplastic Resin Composition>> Next, the thermoplastic resin composition of the present disclosure will be described. The thermoplastic resin composition of the present disclosure contains the above-described plasticizer of the present disclosure and a thermoplastic resin.

[0075] Examples of thermoplastic resins include polyolefins (e.g., polyethylene, polypropylene, etc.), vinyl chloride resins, polyvinyl acetate resins, polyurethane resins, polystyrene resins, AS resins (acrylonitrile-styrene copolymers), ABS resins (acrylonitrile-butadiene-styrene copolymers), AXS resins (styrene copolymers of rubber components other than acrylonitrile-butadiene), acrylic resins, polymethyl methacrylate resins, polyester resins, polyamide resins, etc. Of these, vinyl chloride resins are preferred.

[0076] Vinyl chloride resins are polymers containing structural units derived from vinyl chloride monomers. Vinyl chloride resins may be homopolymers of vinyl chloride monomers, or copolymers of vinyl chloride monomers and carbon-carbon unsaturated bond-containing monomers other than vinyl chloride monomers. Examples of vinyl chloride resins include polyvinyl chloride, ethylene-vinyl chloride copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylic copolymers, vinyl chloride-vinyl acetate copolymers, and chlorinated polyvinyl chloride. The thermoplastic resin composition of the present disclosure may contain only one type of thermoplastic resin, or two or more types of thermoplastic resins.

[0077] The content of the plasticizer in the thermoplastic resin composition can be appropriately set depending on the type of thermoplastic resin, the application of the thermoplastic resin composition, etc. From the viewpoint of easily adjusting the hardness of a resin product formed from the thermoplastic resin composition and obtaining a resin product in which plasticizer bleeding is suppressed, the content of the plasticizer in the thermoplastic resin composition is preferably 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the thermoplastic resin. From the above viewpoints, the content of the plasticizer is more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more per 100 parts by mass of the thermoplastic resin. Furthermore, the content of the plasticizer is more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less per 100 parts by mass of the thermoplastic resin.

[0078] The thermoplastic resin composition may further contain, in addition to the plasticizer and thermoplastic resin, a component different from the plasticizer and thermoplastic resin. Examples of such components include reinforcing agents (calcium carbonate, silica, zinc oxide, titanium oxide, etc.), lubricants (fatty acid esters, higher alcohols, glycerin esters, sorbitan esters, polyhydric alcohols, fatty acids, oil-based waxes, bisamides, etc.), antioxidants, UV absorbers, antioxidants, hydrochloric acid scavengers, flame retardants, antistatic agents, antifogging agents, antibacterial agents, preservatives, and colorants. The amounts of these additives may be appropriately determined depending on each component, as long as they do not impair the effects of the present invention. In one embodiment of the thermoplastic resin composition of the present disclosure containing a component different from the plasticizer and thermoplastic resin, the thermoplastic resin composition contains a plasticizer, a thermoplastic resin, and a lubricant. Another embodiment is a thermoplastic resin composition containing a plasticizer, a thermoplastic resin, a reinforcing agent, and a lubricant.

[0079] For example, when a reinforcing agent is blended into the thermoplastic resin composition, the content of the reinforcing agent is preferably 1 part by mass or more and 80 parts by mass or less, more preferably 2 parts by mass or more and 70 parts by mass or less, and even more preferably 5 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin.

[0080] When a lubricant is blended into the thermoplastic resin composition, the content of the lubricant is preferably 0.1 parts by mass or more and 12 parts by mass or less, more preferably 0.2 parts by mass or more and 10 parts by mass or less, and even more preferably 0.5 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin.

[0081] When an antioxidant is blended into the thermoplastic resin composition, the content of the antioxidant is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.2 parts by mass or more and 10 parts by mass or less, and even more preferably 0.5 parts by mass or more and 7 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin.

[0082] A resin product can be obtained by kneading the above-mentioned thermoplastic resin composition, preferably at a temperature at which the thermoplastic resin in the thermoplastic resin composition melts, and forming or molding it into a desired shape using a known film-forming or molding method. Since the thermoplastic resin in the resin product thus obtained is plasticized using the (meth)acrylic polymer (P), the plasticizer is less likely to volatilize during the resin product manufacturing process, and bleeding of the plasticizer in the resulting resin product can be suppressed. Furthermore, resin products obtained from the thermoplastic resin composition of the present disclosure are less likely to deteriorate in mechanical properties and have good cold resistance even when stored for long periods of time in low-temperature environments (e.g., −20°C or below). In addition, the resin product is less likely to harden and less likely to change color (browning or blackening) even when stored for long periods of time in high-temperature environments, for example, 100°C or above, and has excellent heat resistance.

[0083] Resin products formed using the thermoplastic resin composition of the present disclosure have excellent flexibility, heat resistance, and heat resistance, and are particularly suitable for use in wire coating materials, construction members, agricultural materials, sheets and films for outdoor use, and sheets, films, and leathers for use inside or outside automobiles.

[0084] The present invention will be specifically described below based on examples. However, the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0085] Details of the measurement methods used to evaluate the polymer are as follows. <Molecular weight measurement> Using a gel permeation chromatograph (model "HLC-8320", manufactured by Tosoh Corporation), the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were obtained under the following conditions. Measurement conditions Column: TSKgel SuperMultiporeHZ-M x 4, manufactured by Tosoh Corporation Column temperature: 40°C Eluent: Tetrahydrofuran Detector: RI

[0086] <Viscosity Measurement> Using a TVE-20H viscometer (salt water / plate method, manufactured by Toki Sangyo Co., Ltd.), the viscosity of the polymer was measured with an E-type viscometer under the following conditions: Measurement conditions: Cone shape: angle 1°34', radius 24 mm Temperature: 25°C ± 0.5°C

[0087] <SP value> SP value (unit: [cal / cm ]) measured by the Fedors method ３ ] １／２ <Measurement of Glass Transition Temperature (Tg)> The Tg of the polymer was measured using a differential scanning calorimeter (DSC) under the following conditions. Measurement conditions: DSC: DSC 214 Polymer manufactured by NETZSCH Co. Heating temperature: 10°C / min Measurement atmosphere: nitrogen

[0088] <Quantitative Determination of Double Bond Amount> 1 The amount of double bonds per unit mass of the polymer (i.e., double bond concentration) was calculated from the ratio of the integral value of the signal at around 5.5 ppm derived from hydrogen bonded to the double bond to the integral value of the signal at 3.0 to 4.5 ppm derived from hydrogen bonded to the carbon adjacent to the ester group, as measured by H-NMR, and the composition of the polymer.

[0089] 1. Synthesis of (Meth)acrylic Polymer [Production Example 1] Production of Polymer P-1 The temperature of a 1000 mL pressurized stirred tank reactor equipped with an oil jacket was maintained at 250°C. Next, while maintaining a constant pressure in the reactor, a monomer mixture containing 65 parts of n-butyl acrylate (hereinafter referred to as "BA"), 25 parts of 2-ethylhexyl acrylate (hereinafter referred to as "HA"), 10 parts of tetradecyl acrylate (hereinafter referred to as "TDA"), 50 parts of normal butanol (hereinafter referred to as "n-BuOH"), and 2 parts of di-t-butyl peroxide (manufactured by NOF Corp., trade name "Perbutyl D", hereinafter referred to as "DTBP") as a polymerization initiator was continuously fed from a raw material tank to the reactor at a constant feed rate (48 g / min), and the polymerization reaction was allowed to proceed with a residence time of 12 minutes. In parallel, a reaction liquid equivalent to the amount of the monomer mixture fed was continuously withdrawn from the outlet of the reactor and recovered. Immediately after the start of the reaction, the reaction temperature dropped temporarily, but a temperature rise due to the heat of polymerization was observed. Therefore, the reaction temperature was maintained at 269°C to 271°C (listed as 270°C in Table 1) by controlling the temperature of the oil jacket. The point at which the liquid temperature in the reactor stabilized after the start of the monomer mixture supply was designated as the start point for collecting the reaction liquid, and the reaction was carried out for 25 minutes from the start point. In the reaction step, the amount of the monomer mixture supplied was 1.2 kg, and the amount of the reaction liquid recovered was 1.2 kg. The mixed liquid of polymer, solvent, and unreacted monomer discharged from the reactor was continuously introduced into a thin-film evaporator to separate volatile components such as unreacted monomer, and 0.73 kg of polymer P-1 was obtained.

[0090] [Production Examples 2 to 14, Comparative Production Examples 1 to 4] Polymers P-2 to P-18, which are (meth)acrylic polymers, were obtained in the same manner as in Production Example 1, except that the types and amounts of raw materials used were changed as shown in Tables 1 and 2. In Tables 1 and 2, "LA" represents lauryl acrylate, "SA" represents stearyl acrylate, "GMA" represents glycidyl methacrylate, "IPA" represents isopropyl alcohol, and "MEK" represents methyl ethyl ketone. The monomer composition ratios of Polymers P-1 to P-18 were equivalent to the monomer charging ratios.

[0091]

[0092]

[0093] 2. Production of Thermoplastic Resin Compositions (1) The following thermoplastic resin compositions were produced using the (meth)acrylic polymers obtained in the above Production Examples and Comparative Production Examples as plasticizers. [Example 1] 100 parts of vinyl chloride resin (manufactured by Shin-Dai-Ichi Vinyl Corporation, trade name "ZEST 1300Z"), 70 parts of Polymer P-1, 1.2 parts of calcium stearate, 0.3 parts of zinc stearate, and 2 parts of an antioxidant (manufactured by BASF, trade name "Tinuvin B75") were mixed and kneaded at 160°C using a Laboplastomill to obtain Thermoplastic Resin Composition R-1.

[0094] [Examples 2 to 14, Comparative Examples 1 to 5] Thermoplastic resin compositions R-2 to R-19 were obtained in the same manner as in Example 1, except that the types and amounts of plasticizers used were as shown in Tables 3 and 4. The epoxidized soybean oil used in Tables 3 and 4 was "O-130P" (trade name, manufactured by ADEKA Corporation) (the same applies to Tables 5 and 6).

[0095] 3. Evaluation (1) The following evaluations were carried out using the thermoplastic resin compositions R-1 to R-19 obtained in the above examples and comparative examples. The evaluation results are shown in Tables 3 and 4. <Compatibility> In the production of the above thermoplastic resin compositions, the state of the resin after kneading (degree of cohesion) was observed, and the compatibility was evaluated according to the following criteria. ○: Good compatibility (resin is cohesive and transparent) △: Fair compatibility (resin is cohesive but opaque) ×: Poor compatibility (resin is not cohesive and falls apart overall)

[0096] <Tensile Properties> - Room Temperature Tensile Test The thermoplastic resin composition was press-molded at 190°C to obtain a No. 3 dumbbell test piece (thickness 1 mm). After conditioning the test piece at 23°C and 50% RH for 24 hours, the breaking stress (MPa) and breaking elongation (%) were measured using a tensile tester (Autograph AGS-J, manufactured by Shimadzu Corporation) at a tensile speed of 200 mm / min. - Low Temperature Tensile Test No. 3 dumbbell test pieces prepared in the same manner as in the room temperature tensile test were cooled in a thermostatic chamber at -20°C for 1 hour, and then immediately measured using a tensile tester at a tensile speed of 200 mm / min. The breaking stress (MPa) and breaking elongation (%) were measured using the tensile tester.

[0097] <Heat Resistance Test> Tensile Properties No. 3 dumbbell test specimens prepared in the same manner as in the room-temperature tensile test were heated in a 100°C dryer for 7 days and then conditioned at 23°C and 50% RH for 24 hours. Subsequently, the breaking stress (MPa) and breaking elongation (%) were measured at a tensile speed of 200 mm / min using a tensile tester (Autograph AGS-J, manufactured by Shimadzu Corporation), and the elongation retention (%) was calculated. The elongation retention represents the ratio Q2 (unit: %) of the breaking elongation after heat treatment at 100°C to the breaking elongation Q1 in the room-temperature tensile test. The elongation retention is expressed by the following formula: Elongation retention [unit: %] = (Q2 / Q1) × 100. The higher the elongation retention value, the less likely the test specimen is to harden in a high-temperature environment, and the better its heat resistance.

[0098] - Staining resistance No. 3 dumbbell test pieces prepared in the same manner as in the room temperature tensile test were placed in a dryer at 100°C, and the test pieces were removed after 1 day, 2 days, 3 days, and 7 days, and the number of days until browning or blackening was measured. The longer the number of days until browning or blackening, the better the staining resistance was judged to be. The criteria for judging staining are as follows: ○: No staining △: Light staining observed (transparent) ×: Browning or blackening (opaque) The staining resistance was comprehensively evaluated based on the number of days until browning or blackening occurred. The criteria for the comprehensive evaluation of staining resistance are as follows: ◎: No staining on the test piece after 7 days, particularly good staining resistance ○: No staining on the test piece after 1 to 3 days, but light staining observed on the test piece after 7 days, good staining resistance △: No staining on the test piece after 1 to 3 days, but browning or blackening observed on the test piece after 7 days, fair staining resistance ×: Browning or blackening observed on the test piece after 3 days, poor staining resistance

[0099]

[0100]

[0101] 4. Production of Thermoplastic Resin Composition (2) The following thermoplastic resin compositions were produced using the (meth)acrylic polymers obtained in the above Production Examples and Comparative Production Examples as plasticizers. [Example 15] 100 parts of vinyl chloride resin (manufactured by Shin-Dai-Ichi Vinyl Corporation, trade name "ZEST 1300Z"), 70 parts of Polymer P-1, 30 parts of calcium carbonate (manufactured by Maruo Calcium Co., Ltd., trade name "Super SSS"), 10 parts of titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., trade name "Tipake R820"), 1.2 parts of calcium stearate, 0.3 parts of zinc stearate, and 2 parts of an antioxidant (manufactured by BASF, trade name "Tinuvin B75") were mixed and kneaded at 160°C using a Labo Plastomill to obtain Thermoplastic Resin Composition R-20.

[0102] [Examples 16 to 28, Comparative Examples 6 to 10] Thermoplastic resin compositions R-21 to R-38 were obtained in the same manner as in Example 15, except that the types and amounts of plasticizers used were as shown in Tables 5 and 6.

[0103] 5. Evaluation (2) The following evaluations were carried out using the thermoplastic resin compositions R-20 to R-38 obtained in the above examples and comparative examples. The evaluation results are shown in Tables 5 and 6.

[0104] <Cold Resistance> (Evaluation of Cold Resistance of Test Specimens Initially After Production (Before Weather Resistance Test)) The thermoplastic resin composition was press-molded at 190°C to obtain test specimens measuring 38 mm in length, 6 mm in width, and 2 mm in thickness. These test specimens were conditioned at 23°C and 50% RH for 24 hours. Thereafter, a brittle temperature tester (S-type, manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used to check whether or not the test specimens would break at -20°C and -25°C (low-temperature impact test). The number of test specimens was three, and cold resistance was evaluated according to the following criteria. ○: No fracture in any test specimens △: Fracture occurred in one or two test specimens ×: Fracture occurred in all test specimens (Evaluation of cold resistance of test specimens after weather resistance test) Test specimens of the same shape and size as those used in the cold resistance evaluation of the test specimens immediately after production were placed in a metaling weather meter "DAIPLA METAL WEATHER KU-R5NCI-A" (trade name) manufactured by Daipla Wintes Co., Ltd., and subjected to an accelerated weather resistance test. The accelerated conditions were a metal halide lamp illuminance of 80 mW / cm ２ The test environment was a temperature of 63°C, humidity of 70% RH, and a two-minute shower every two hours. This procedure was repeated for 1,200 hours, and then a low-temperature impact resistance test was carried out using the same evaluation method as above to evaluate the cold resistance.

[0105]

[0106]

[0107] As is clear from the results in Tables 3 to 6, (meth)acrylic polymers P-1 to P-14, which contain structural units derived from (meth)acrylic acid alkyl esters having an alkyl group containing 10 or more carbon atoms and have glass transition temperatures of −75°C or lower, exhibited good compatibility with vinyl chloride resin. Furthermore, thermoplastic resin compositions containing (meth)acrylic polymers P-1 to P-14 and vinyl chloride resin exhibited suppressed deterioration in mechanical properties and little change in color even when stored for long periods at 100°C (Examples 1 to 14). Furthermore, even when stored for long periods at −20°C or lower, they were resistant to deterioration in mechanical properties and showed good cold resistance after weathering tests (Examples 15 to 28).

[0108] In contrast, when (meth)acrylic polymers P-15 to P-17, which do not contain structural units derived from (meth)acrylic acid alkyl esters having an alkyl group having 10 or more carbon atoms, were used as plasticizers (Comparative Examples 1 to 4, 6 to 9), and when (meth)acrylic polymer P-18, which contains structural units derived from (meth)acrylic acid alkyl esters having an alkyl group having 10 or more carbon atoms but has a glass transition temperature exceeding −75 ° C., was used as a plasticizer (Comparative Examples 5 and 10), both heat resistance and cold resistance were inferior compared to Examples 1 to 28. More specifically, when (meth)acrylic polymer P-17, which has an SP value of less than 9.30, was used as a plasticizer (Comparative Examples 3 and 8), the plasticizer was incompatible with vinyl chloride resin, making molding difficult. Furthermore, in Comparative Example 8, many cracks were observed in the test piece (2 mm thick) prepared for cold resistance evaluation, so it was determined that cold resistance evaluation was not possible.

[0109] From the above results, it has become clear that a thermoplastic resin composition excellent in flexibility, cold resistance, and heat resistance can be obtained by using a plasticizer containing a (meth)acrylic polymer having a weight average molecular weight of 3,000 or less, which contains structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group of 9 or less carbon atoms in the ester moiety, and structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group of 10 or more carbon atoms in the ester moiety, and which has a glass transition temperature of −75° C. or less.

[0110] The present invention is not limited to the above-described embodiments, and encompasses various modifications and equivalent modifications within the scope of the spirit of the present invention. Therefore, in light of the above teachings, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are to be understood as falling within the scope and spirit of the present invention.

Claims

1. A plasticizer containing a (meth)acrylic polymer having a weight-average molecular weight of 3,000 or less, wherein the (meth)acrylic polymer contains a structural unit (U1) derived from a (meth)acrylic acid alkyl ester having an alkyl group with 9 or less carbon atoms in the ester moiety, and a structural unit (U2) derived from a (meth)acrylic acid alkyl ester having an alkyl group with 10 or more carbon atoms in the ester moiety, and wherein the plasticizer has a glass transition temperature of -75°C or less.

2. The plasticizer according to claim 1, wherein the content of the structural unit (U2) is 1 to 50 mass % based on the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer.

3. The plasticizer according to claim 1, having an SP value of 9.30 or more.

4. The plasticizer according to claim 1, wherein the (meth)acrylic polymer has a carbon-carbon double bond content of 0.01 to 0.50 meq / g.

5. The plasticizer described in claim 1, wherein the content of structural units derived from (meth)acrylic acid alkyl ester is 90 mass% or more relative to the total amount of structural units derived from the monomers constituting the (meth)acrylic polymer.

6. The plasticizer according to claim 1, which is used for plasticizing vinyl chloride resins.

7. A thermoplastic resin composition comprising the plasticizer according to any one of claims 1 to 6 and a thermoplastic resin.

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