JP7338984B2 - Styrene-based resin composition and molded article - Google Patents

Description

The present invention relates to a styrenic resin composition and molded articles.

Styrenic resins are used in a wide range of applications due to their excellent moldability, dimensional stability, and transparency. In addition, biomass materials have attracted attention from the viewpoint of environmental protection, and composite materials of resin materials and naturally-derived organic fillers or biopolymers are being studied.
For example, Patent Literatures 1 and 2 disclose styrenic composite resin compositions comprising styrenic resins and cellulosic materials. Further, Patent Document 3 discloses a vehicle lamp made of polystyrene and nanocellulose (hereinafter also referred to as CNF). Furthermore, Patent Literatures 4 and 5 disclose a composition comprising a styrene resin and modified CNF.

JP-A-7-173352 JP-A-8-231795 WO2014/017274 JP 2016-176052 A Patent No. 6394934

However, in Patent Documents 1 and 2, wood flour, pulp, or the like having a large fiber diameter is used, and when added to a styrenic resin, the impact strength and molding appearance are greatly reduced, and the products are limited. In addition, this technique cannot improve the dispersibility of nanocellulose having a nano-order fiber diameter, and cannot improve the appearance, which is the characteristic of nanocellulose, or the characteristics in a small amount. Although Patent Document 3 describes polystyrene and CNF, only PP and jute fibers with a large fiber diameter are described in Examples, and there is no technical disclosure of polystyrene containing CNF. In addition, since Patent Documents 4 and 5 use modified CNF, modification is costly, and unreacted modifiers remain, heat resistance, impact resistance, moldability, foaming characteristics, etc. There is a problem of declining

Accordingly, an object of the present invention is to provide a styrenic resin composition having excellent rigidity, impact resistance, heat resistance, appearance, moldability and foaming properties, and a molded article containing the styrenic resin composition.

In view of the above problems, the present inventors have made intensive research and repeated experiments, and found that conventional styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomers The present inventors have found that the above problems can be solved by using a resin composition in which a copolymer resin containing units and a specific nanocellulose are mixed in a specific ratio, and have completed the present invention.
That is, the present invention is as follows.

[1] (a) 80.0 to 99.7% by mass of a copolymer resin containing styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units; (b) A styrene-based resin composition comprising 0.3 to 20.0% by mass of nanocellulose having an average fiber diameter of 3 to 200 nm.
[2] The copolymer resin (a) has a total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units of 100% by mass. When containing 69.0 to 98.0% by mass of the styrene-based monomer unit, and containing 2.0 to 16.0% by mass of the unsaturated carboxylic acid-based monomer unit, and The styrenic resin composition according to [1] above, containing 0.0 to 15.0% by mass of unsaturated carboxylic acid ester-based monomer units.
[3] The styrenic resin composition according to [1] or [2] above, wherein the unsaturated carboxylic acid monomer of the copolymer resin (a) is methacrylic acid.
[4] A molded article comprising the styrenic resin composition according to any one of [1] to [3] above.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a styrenic resin composition and a molded article that are excellent in rigidity, impact resistance, heat resistance, appearance, moldability and foaming properties.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail. can be implemented.

[Styrene resin composition]
The styrenic resin composition of the present embodiment comprises (a) a copolymer resin containing styrenic monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units.80. 0 to 99.7% by mass, and (b) 0.3 to 20.0% by mass of nanocellulose having an average fiber diameter of 3 to 200 nm. Hereinafter, (a) a copolymer resin containing a styrene-based monomer unit, an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit is simply referred to as (a) a copolymer resin or Also referred to as (a) component, and (b) nanocellulose having an average fiber diameter of 3 to 200 nm is also referred to as (b) nanocellulose or (b) component.

<(a) Copolymer resin>
In the present embodiment, the content of the (a) copolymer resin containing styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is When the total mass of the copolymer resin and (b) nanocellulose is 100% by mass, it is 80.0 to 99.7% by mass, preferably 85.0 to 99.5% by mass, more preferably 90.0 to It is 99.0% by mass. By setting the content to 80.0% by mass or more, impact and appearance moldability can be enhanced. On the other hand, by setting the content to 99.7% by mass or less, the total content of (b) nanocellulose can be ensured, and rigidity, impact, etc. can be improved.

In the copolymer resin (a), when the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is 100% by mass, The content of styrene-based monomer units is preferably 69.0 to 96.0% by mass, more preferably 74.0 to 92.0% by mass, and still more preferably 77.0 to 87.0% by mass. It is in the range of % by mass. By making the content 69.0% by mass or more, the fluidity of the resin can be improved, while by making the content 96.0% by mass or less, the unsaturated carboxylic acid-based It becomes difficult to allow the monomer units and the unsaturated carboxylic acid ester-based monomer units to exist in desired amounts, making it difficult to obtain the below-described effects of these monomer units.

In the resin composition of the present embodiment, the unsaturated carboxylic acid-based monomer unit plays a role of improving dispersibility and heat resistance of (b) nanocellulose. (a) When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the copolymer resin is 100% by mass, unsaturated carboxylic acid The content of acid monomer units is preferably 2.0 to 16.0% by mass, more preferably 4.0 to 16.0% by mass, and still more preferably 6.0 to 14.0% by mass. % by mass, particularly preferably 8.0 to 13.0% by mass. By making the content 2.0% by mass or more, the dispersibility and heat resistance of (b) nanocellulose can be further improved, while by making the content 16.0% by mass or less (b) It is possible to prevent deterioration of properties due to thermal deterioration of nanocellulose, and to improve fluidity and mechanical properties.

In general, styrene-methacrylic acid-based resins including styrene-methacrylic acid-methyl methacrylate copolymer resins are produced by radical polymerization in most cases on an industrial scale. Therefore, when polymerizing the (a) copolymer resin, various alcohols may be added to the polymerization system.

In the present embodiment, the unsaturated carboxylic acid ester-based monomer suppresses the dehydration reaction of the unsaturated carboxylic acid-based monomer through intermolecular interaction with the unsaturated carboxylic acid-based monomer, and It can be used to improve the mechanical strength of the resin. Furthermore, the unsaturated carboxylic acid ester-based monomer contributes to the improvement of resin properties such as (b) nanocellulose dispersion, weather resistance, and surface hardness.

When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is 100% by mass, unsaturated carboxylic acid ester-based monomer units The content of is preferably 0.0 to 15.0% by mass, more preferably 1.0 to 12.0% by mass, still more preferably 2.0 to 10.0% by mass. By setting the content to 15.0% by mass or less, the fluidity of the resin can be improved and the water absorption can be suppressed. Further, by setting the content of the unsaturated carboxylic acid ester-based monomer unit to 0.0% by mass, it is possible to improve heat resistance and reduce costs. The content of monomeric units can also be greater than 0.0% by mass.

When an unsaturated carboxylic acid-based monomer and an unsaturated carboxylic acid ester-based monomer unit are bonded side by side, if a high-temperature, high-vacuum devolatilization apparatus is used, a dealcoholization reaction may occur depending on the conditions. Six-membered cyclic anhydrides may be formed. The (a) copolymer resin of the present embodiment may contain this six-membered cyclic acid anhydride, but it is preferable that the amount is less because it lowers the fluidity.

In the present embodiment, the contents of styrene monomer units, methacrylic acid monomer units and methyl methacrylate monomer units in the copolymer resin (a) are each determined by proton nuclear magnetic resonance ( ¹ H-NMR ) can be obtained from the integral ratio of the spectrum measured by the measuring instrument.

In the present embodiment, (a) the copolymer resin contains monomer units other than styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units. Although it is not excluded to further contain within the range that does not impair the effect of the invention, typically, styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units consists of

Examples of styrene-based monomers include, but are not limited to, styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, and vinyltoluene. , ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene, chlorostyrene, and indene. As the styrene-based monomer, styrene is preferable from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more.

Examples of unsaturated carboxylic acid-based monomers include, but are not particularly limited to, methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, and itaconic acid. As the unsaturated carboxylic acid-based monomer (b), methacrylic acid is preferable because it has a large effect of improving the dispersibility and heat resistance of nanocellulose, and is liquid at room temperature and has excellent handleability. These unsaturated carboxylic acid-based monomers can be used singly or in combination of two or more.

Furthermore, the unsaturated carboxylic acid ester monomer is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, (meth) ) cyclohexyl acrylate and the like. As the (meth)acrylic acid ester-based monomer, methyl (meth)acrylate is preferable because it has little effect on deterioration of heat resistance. These unsaturated carboxylic acid ester monomers can be used singly or in combination of two or more.

In the present embodiment, (a) the weight average molecular weight (Mw) of the copolymer resin is preferably 100,000 to 350,000, more preferably 120,000 to 300,000, still more preferably 140,000 to 240,000. When the weight-average molecular weight (Mw) is from 100,000 to 350,000, a resin having excellent balance between mechanical strength and fluidity can be obtained, and gel matter is less mixed. The weight average molecular weight (Mw) is a value obtained by standard polystyrene conversion using gel permeation chromatography.

In the present embodiment, the melt flow rate of (a) the copolymer resin is preferably 0.3 to 5.0 g/10 min, more preferably 0.4 to 4.0 g/10 min, still more preferably 0.4 to 3.0 g/10 min. When the melt flow rate is 0.3 g/10 min or more, it is preferable from the viewpoint of dispersibility and fluidity of (b) nanocellulose, and when it is 5.0 g/10 min or less, it is preferable from the viewpoint of the mechanical strength of the resin. . The melt flow rate is a value measured at 200° C. and a load of 49 N in accordance with ISO 1133.

In the present embodiment, the method for polymerizing the copolymer resin (a) is not particularly limited, but for example, a bulk polymerization method or a solution polymerization method can be suitably employed as a radical polymerization method. The polymerization method mainly includes a polymerization step of polymerizing raw materials for polymerization (monomer components) and a devolatilization step of removing volatile matter such as unreacted monomers and polymerization solvent from the polymerization product.
Hereinafter, the method for polymerizing the copolymer resin (a) that can be used in the present embodiment will be described.

(a) When the raw materials for polymerization are polymerized to obtain a copolymer resin, the raw material composition for polymerization typically contains a polymerization initiator and a chain transfer agent. Examples of polymerization initiators include organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl-4,4-bis(t -Butylperoxy)valerate and other peroxyketals, dialkylperoxides such as di-t-butylperoxide, t-butylcumylperoxide and dicumylperoxide, diacylperoxides such as acetylperoxide and isobutyrylperoxide, diisopropylperoxydi Examples include peroxydicarbonates such as carbonates, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. Among them, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoint of decomposition rate and polymerization rate.

Examples of chain transfer agents include α-methylstyrene linear dimer, n-dodecylmercaptan, t-dodecylmercaptan, n-octylmercaptan and the like.

As a polymerization method, solution polymerization using a polymerization solvent can be employed as necessary. Examples of the polymerization solvent to be used include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone, each of which may be used alone or in combination of two or more. Other polymerization solvents such as aliphatic hydrocarbons can be further mixed with the aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. These polymerization solvents are preferably used in an amount not exceeding 25 parts by mass with respect to 100 parts by mass of the total monomers. If the amount of the polymerization solvent exceeds 25 parts by mass with respect to 100 parts by mass of the total monomers, the polymerization rate tends to decrease significantly and the mechanical strength of the resulting resin tends to decrease significantly. Addition of 5 to 20 parts by mass per 100 parts by mass of all monomers prior to polymerization facilitates homogenization of quality and is also preferable from the viewpoint of polymerization temperature control.

In the present embodiment, (a) the apparatus used in the polymerization step for obtaining the copolymer resin is not particularly limited, and may be appropriately selected according to the polymerization method of the styrene-based resin. For example, in the case of bulk polymerization, a polymerization apparatus in which one or a plurality of complete mixing reactors are connected can be used. The devolatilization step is not particularly limited, and in the case of bulk polymerization, the polymerization is continued until the final unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less. In order to remove volatile matter such as, devolatilization treatment is performed by a known method. For example, ordinary devolatilizers such as flash drums, twin-screw devolatilizers, thin film evaporators and extruders can be used, but devolatilizers with a small stagnant portion are preferred. The temperature of the devolatilization treatment is usually about 190 to 280° C., and more preferably 190 to 260° C. from the viewpoint of suppressing the formation of a six-membered cyclic acid anhydride due to the adjacency of methacrylic acid and methyl methacrylate. . The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method of reducing the pressure under heating to remove the volatile matter, and a method of removing the volatile matter through an extruder or the like designed for the purpose of removing the volatile matter.

<(b) Nanocellulose>
(b) Nanocellulose in the present embodiment is cellulose having an average fiber diameter of 3 to 200 nm. (b) The content of nanocellulose is 0.3 to 20.0% by mass, preferably 0.5 to 20.0% by mass, with respect to 100% by mass of the total mass of (a) copolymer resin and (b) nanocellulose. 15.0% by mass, more preferably 1.0 to 10.0% by mass. (b) The mechanical strength can be improved by setting the content of nanocellulose to 0.3% by mass or more. On the other hand, if the content is too large, the impact is lowered, and (b) appearance defects that appear to be aggregates of nanocellulose occur, and fluidity is lowered, resulting in significantly reduced moldability. The cellulose content in the composition can be found by dissolving the composition in a solvent that dissolves the copolymer resin, taking out the undissolved matter, and measuring the mass after drying at 120° C. for 4 hours.

(b) Nanocellulose has an average fiber diameter of 3 to 200 nm, preferably 10 to 150 nm, more preferably 20 to 100 nm. If the average fiber diameter is outside the above range, the effect of improving rigidity may not be sufficiently exhibited, and the impact and molding appearance may deteriorate. In the present invention, the average fiber diameter refers to the average value of the fiber diameters measured at 100 locations with an electron microscope magnified 5000 times.

(b) Fibers constituting nanocellulose are not particularly limited as long as they are formed of polysaccharides having a β-1,4-glucan structure. , hardwood pulp, etc.), bamboo fiber, sugarcane fiber, seed hair fiber (cotton linter, bombax cotton, kapok, etc.), ginskin fiber (e.g., hemp, paper mulberry, mitsumata, etc.), leaf fiber (e.g., Manila hemp) , New Zealand hemp, etc.) and other natural cellulose fibers (pulp fibers)], animal-derived cellulose fibers (sea squirt cellulose, etc.), bacterial-derived cellulose fibers, chemically synthesized cellulose fibers [cellulose acetate (cellulose acetate), Organic acid esters such as cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate; inorganic acid esters such as cellulose nitrate, cellulose sulfate, cellulose phosphate; mixed acid esters such as cellulose acetate nitrate; Cellulose (e.g., hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, etc.); carboxyalkyl cellulose (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl cellulose (methyl cellulose, ethyl cellulose, etc.); regenerated cellulose (rayon, cellophane, etc.), etc. cellulose derivative fibers, etc.] and the like. You may use these (b) fibers which comprise nanocellulose individually or in combination of 2 or more types.

Among these (b) fibers constituting nanocellulose, the production efficiency is high in terms of dispersibility, rigidity, and impact resistance when producing (b) nanocellulose, and it has an appropriate fiber diameter and fiber length. Therefore, plant-derived cellulose fibers, for example, pulp-derived cellulose fibers such as wood fibers (softwood, hardwood, bamboo pulps, etc.) and seed hair fibers (cotton linter pulp, etc.) are preferable.

<Optional Addition Ingredients>
In addition to the above components (a) to (b), the styrenic resin composition of the present embodiment includes, if necessary, known additives, processing aids, and other additive components within a range that does not impair the effects of the present invention. can be added. These additives, processing aids and the like include antioxidants, weathering agents, lubricants, antistatic agents, fillers and the like.

Antioxidants include phenol compounds, phosphorus compounds, thioether compounds and the like.
Phenolic antioxidants include, for example, 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, distearyl (3,5-di-tert-butyl-4- hydroxybenzyl)phosphonate, 1,6-hexamethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 4,4'-thiobis(6-tert-butyl-m-cresol) , 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis(6-tert-butyl- m-cresol), 2,2′-ethylidenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(4-tert-butyl-6-tert-butylphenol), 1,1,3- tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, 1,3 ,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6 -trimethylbenzene, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, stearyl [3-(3,5-di-tert-butyl-4 -hydroxyphenyl)propionate], tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)methyl propionate]methane, thiodiethylene glycol bis[(3,5-di-tert-butyl-4-hydroxyphenyl) ) propionate], 1,6-hexamethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butyl acid] glycol ester, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris[(3 ,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 3,9-bis[1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl ) propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], etc. mentioned.
These may be used in combination of two or more.

Examples of phosphorus antioxidants include tris(2,4-di-tert-butylphenyl) phosphite, trisnonylphenyl phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4- Hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecylphosphite, octyldiphenylphosphite, di(decyl)monophenylphosphite, di(tridecyl)pentaerythritol diphosphite, di(nonylphenyl) ) pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2 ,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(tridecyl)- 4,4′-n-butylidenebis(2-tert-butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, tetrakis (2,4-di-tert-butylphenyl) biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis ( 4,6-tert-butylphenyl)-2-ethylhexylphosphite, 2,2′-methylenebis(4,6-tert-butylphenyl)-octadecylphosphite, 2,2′-ethylidenebis(4,6-di tert-butylphenyl)fluorophosphite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl) oxy]ethyl)amine, phosphites of 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert-butylphenol, and the like.
These may be used in combination of two or more.

Thioether-based antioxidants include, for example, dilauryl thiodipropionate, dimyristyl thiodipropionate, dialkylthiodipropionates such as distearyl thiodipropionate, and pentaerythritol tetra(β-alkylmercaptopropionates is mentioned.
These may be used in combination of two or more.

As the weather resistant agent, an ultraviolet absorber, a hindered amine light stabilizer, and the like can be used.
UV absorbers include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 5,5′-methylenebis(2-hydroxy-4-methoxybenzophenone) 2-hydroxybenzophenones such as; 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzo triazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octyl Phenyl)benzotriazole, 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, 2,2'-methylenebis(4-tert-octyl-6-(benzotriazolyl)phenol ), 2-(2′-hydroxyphenyl)benzotriazoles such as 2-(2′-hydroxy-3′-tert-butyl-5′-carboxyphenyl)benzotriazole; phenyl salicylate, resorcinol monobenzoate, 2,4 -di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-di-tert-amylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl-3,5 - benzoates such as di-tert-butyl-4-hydroxybenzoate; substituted oxanilides such as 2-ethyl-2'-ethoxyoxanylide and 2-ethoxy-4'-dodecyloxanilide; ethyl-α-cyano- Cyanoacrylates such as β,β-diphenyl acrylate and methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate; 2-(2-hydroxy-4-octoxyphenyl)-4,6- Bis(2,4-di-tert-butylphenyl)-s-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-s-triazine, 2-(2-hydroxy-4-propoxy -5-methylphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine and other triaryltriazines.
These may be used in combination of two or more.

Examples of hindered amine light stabilizers include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6 ,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-tetramethyl-4-piperidyl) sebacate , bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4- butane tetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate, bis(2,2,6,6-tetramethyl- 4-piperidyl)・di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)・di(tridecyl)-1,2 , 3,4-butane tetracarboxylate, bis(1,2,2,4,4-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl) Malonate, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol/diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetra methyl-4-piperidylamino)hexane/2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/ 2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2,2,6,6 -tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis[2,4-bis(N- Butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8-12-tetraazadodecane, 1,6,11 -tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane, 1,6,11 - Hindered amine compounds such as tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane mentioned.
These may be used in combination of two or more.

Fatty acid amides, fatty acid esters, fatty acids, fatty acid metal salts and the like can be used as lubricants.
Examples of aliphatic amide lubricants include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, and ethylene bis lauric acid amide. be done.
These may be used in combination of two or more.

Aliphatic ester lubricants include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, and palmitic acid. Isopropyl, octyl palmitate, coconut fatty acid octyl ester, octyl stearate, tallow fatty acid octyl ester, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, C28-30 linear, unbranched saturated esters of monocarboxylic acid (hereinafter abbreviated as montanic acid) and ethylene glycol, esters of montanic acid and glycerin, esters of montanic acid and butylene glycol, esters of montanic acid and trimethylolethane, esters of montanic acid and trimethylolpropane, Esters of montanic acid and pentaerythritol, glycerin monostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, poly Oxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate and the like.
These may be used in combination of two or more.

Specific examples of saturated fatty acids among fatty acid-based lubricants include lauric acid (dodecanoic acid), isodecanoic acid, tridecylic acid, myristic acid (tetradecanoic acid), pentadecic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), ), stearic acid (octadecanoic acid), isostearic acid, tubercrostearic acid (nonadecanic acid), 2-hydroxystearic acid, arachidic acid (icosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetradocosanoic acid), cerotic acid (hexadocosanoic acid), montanic acid (octadocosanoic acid), melissic acid and the like, particularly lauric acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid and montanic acid.

Among fatty acid-based lubricants, unsaturated fatty acids specifically include myristoleic acid (tetradecenoic acid), palmitoleic acid (hexadecenoic acid), oleic acid (cis-9-octadecenoic acid), elaidic acid (trans-9-octadecene acid), ricinoleic acid (octadecadienoic acid), vaccenic acid (cis-11-octadecenoic acid), linoleic acid (octadecadienoic acid), linolenic acid (9,11,13-octadecatrienoic acid), elestearic acid (9,11,13-octadecatrienoic acid), gadoleic acid (icosanoic acid), erucic acid (docosanoic acid), nervonic acid (tetradocosanoic acid) and the like.
These may be used in combination of two or more.

Fatty acid metal salt-based lubricants include lithium salts, calcium salts, magnesium salts, and aluminum salts of fatty acids of the above fatty acid-based lubricants.
These may be used in combination of two or more.

Cationic, anionic, nonionic, amphoteric, and fatty acid partial esters such as glycerin fatty acid monoester can be used as antistatic agents.
Specifically, alkyltrimethylammonium salts, dialkyldimethylammonium salts, benzalkonium salts, N,N-bis(2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl)methylammonium mesosulphate , (3-laurylamidopropyl)trimethylammonium methylsulfate, stearamidopropyldimethyl-2-hydroxyethylammonium nitrate, stearamidopropyldimethyl-2-hydroxyethylammonium phosphate, cationic polymer, alkylsulfonate , Alkyl benzene sulfonate, Sodium alkyl diphenyl ether disulfonate, Alkyl nitrate ester salt, Phosphate alkyl ester salt, Alkyl phosphate amine salt, Stearate monoglyceride, Pentaerythritol fatty acid ester, Sorbitan monopalmitate, Sorbitan monostearate, Diglycerin fatty acid Esters, alkyldiethanolamines, alkyldiethanolamine fatty acid monoesters, alkyldiethanolamides, polyoxyethylene dodecyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol monolaurates, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyether block copolymers , cetyl betaine, hydroxyethylimidazoline sulfate, and the like.
These may be used in combination of two or more.

Talc, calcium carbonate, barium sulfate, carbon fiber, mica, wollastonite, whiskers, and the like can be used as fillers.
In addition, anti-blocking agents, coloring agents, anti-blooming agents, surface treatment agents, antibacterial agents, anti-stain agents (silicone oil described in JP-A-2009-120717, monoamide compounds of higher aliphatic carboxylic acids, and higher fatty acid It is also possible to add a build-up inhibitor such as a monoester compound obtained by reacting a group carboxylic acid with a monohydric to trihydric alcohol compound.

The total content of optional components such as additives and processing aids may be 0.05 to 5% by mass in the styrenic resin composition.

The styrenic resin composition of the present embodiment may consist essentially of components (a) to (b) and optional additive components. Further, it may consist of only components (a) to (b), or only components (a) to (b) and optionally added components.
"Consisting essentially of (a) to (b) and optional components" means that 95 to 100% by mass (preferably 98 to 100% by mass) of the styrene resin composition is (a) to It means the component (b), or components (a) to (b) and an optional additive component.
The styrenic resin composition of the present embodiment may contain unavoidable impurities in addition to the components (a) to (b) and optional additive components within a range that does not impair the effects of the present invention.

[Physical properties of styrene resin composition]
<Flexural modulus>
The flexural modulus of the styrene-based resin composition of the present embodiment is preferably 2500 MPa or more, more preferably 3000 MPa or more. If it is less than 2500 MPa, the thickness of the product cannot be reduced, and the weight cannot be reduced.
In the present disclosure, the flexural modulus is a value measured according to ISO 178.

<Charpy impact strength>
The Charpy impact strength of the styrenic resin composition of the present embodiment is preferably 1.0 kJ/m ² or more, more preferably 1.5 kJ/m ² or more. If it is less than 1.0 kJ/m ² , there is a concern that damage may occur during use due to impact or the like depending on the application.
In the present disclosure, the Charpy impact strength is a value measured with a notch according to ISO 179.

<Vicat softening temperature>
The Vicat softening temperature of the styrenic resin composition of the present embodiment is preferably 100°C or higher, more preferably 105°C or higher. If it is less than 100°C, the temperature may rise during use and the product may be deformed.
In the present disclosure, the Vicat softening temperature is a value measured under the conditions of a load of 49 N and a heating rate of 50° C./hour in accordance with ISO 306.

<Melt flow rate (MFR)>
The melt flow rate of the styrenic resin composition of the present embodiment is preferably 0.5 g/10 minutes or more, more preferably 0.8 g/10 minutes or more. If it is less than 0.5 g/10 minutes, the fluidity is low, and it is necessary to raise the processing temperature.
In the present disclosure, the melt flow rate is a value measured under conditions of a temperature of 200° C. and a load of 49 N in accordance with ISO1133.

<Yellow index>
The yellow index of the styrene-based resin composition of the present embodiment is preferably 30 or less, more preferably 25 or less. When it is 25 or less, the yellowness of the molded article obtained using the resin composition can be suppressed.
In the present disclosure, the yellow index is a value measured according to JIS K 7373:2006.

[Method for producing styrene resin composition]
The styrenic resin composition of the present embodiment can be produced by melt-kneading each component by an arbitrary method. For example, a method using a high-speed stirrer typified by a Henschel mixer, a batch kneader typified by a Banbury mixer, a single-screw or twin-screw continuous kneader, a roll mixer, or the like may be used alone or in combination. The heating temperature during kneading is usually selected in the range of 180 to 250°C.

[Molding]
The styrene-based resin composition of the present embodiment can be produced by injection molding, injection compression molding, extrusion molding, or blow molding using the above-described melt-kneading molding machine or pellets of the obtained styrene-based resin composition as raw materials. A molded product can be produced by a method, a press molding method, a vacuum molding method, a foam molding method, or the like.

Molded articles, preferably injection-molded articles (including injection compression), containing the styrene resin composition of the present embodiment are used in office automation equipment such as copiers, facsimiles, personal computers, printers, information terminals, refrigerators, vacuum cleaners, and microwave ovens. It is suitably used for equipment, household appliances, housings and various parts of electric and electronic equipment, interior and exterior parts of automobiles, construction materials, foamed heat insulating materials, insulating films, and the like.

EXAMPLES The embodiments of the present invention will be described in more detail below based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

<Measurement and evaluation method>
The physical properties of the resin compositions obtained in Examples and Comparative Examples were measured and evaluated according to the following methods.
(1) Contents of styrene monomer units, methacrylic acid monomer units, and methyl methacrylate monomer units in copolymer resin Spectra measured with a proton nuclear magnetic resonance ( ¹ H-NMR) spectrometer The resin composition was quantified from the integral ratio of .
・Sample preparation: 30 mg of resin pellets were dissolved in 0.75 mL of d ₆ -DMSO by heating at 60° C. for 4 to 6 hours.
・Measurement equipment: JNM ECA-500 manufactured by JEOL Ltd.
Measurement conditions: measurement temperature of 25° C., observation core ^{of 1} H, accumulation times of 64, repetition time of 11 seconds.

(Assignment of spectra)
For spectral assignments measured in dimethylsulfoxide deuterated solvent, the peaks at 0.5-1.5 ppm are the hydrogens of the α-methyl groups of methacrylic acid, methyl methacrylate, and the six-membered cyclic anhydride, 1.6 The peak at ~2.1 ppm is the hydrogen of the methylene group of the polymer main chain, the peak of 3.5 ppm is the hydrogen of the carboxylic acid ester ( _-COOCH3 ) of methyl methacrylate, and the peak of 12.4 ppm is the hydrogen of the carboxylic acid of methacrylic acid. is. Also, the peak at 6.5 to 7.5 ppm is the hydrogen of the aromatic ring of styrene. In addition, since the resins of the present examples and comparative examples have a small content of six-membered cyclic acid anhydride, quantification is usually difficult by this measuring method.

(2) (a) Weight Average Molecular Weight of Copolymer Resin (a) The weight average molecular weight of the copolymer resin was measured under the following conditions and procedures.
- Sample preparation: About 0.05% by mass of resin was dissolved in tetrahydrofuran.
・Measurement conditions Equipment: TOSOH HLC-8220GPC
(Gel permeation chromatography)
Column: super HZM-H
Temperature: 40°C
Carrier: THF 0.35 mL/min
Detector: RI, UV: 254 nm
Calibration curve: Created using TOSOH standard PS.

(3) Melt flow rate (MFR)
The melt mass flow rate (g/10 minutes) of the styrene copolymer resin was measured according to ISO 1133 (200°C, load 49N).

(4) Flexural modulus The flexural modulus (MPa) was measured according to ISO 178 using a test piece prepared by the method described below.

(5) Charpy impact strength Charpy impact strength (kJ/m ² ) was measured with a notch according to ISO 179 using a test piece prepared by the method described below.

(6) Vicat softening temperature The Vicat softening temperature (°C) was measured in accordance with ISO 306 using a test piece prepared by the method described below under the conditions of a load of 49 N and a heating rate of 50°C/hour.

(7) Surface Appearance For the surface appearance, one surface of the test piece prepared by the method described later is observed, and if there are less than 20 dents with an opening of 0.1 mm or more, it is regarded as "OK", and 20 A case in which more than one existed was evaluated as "NG".

(8) YI (yellow index)
YI was measured with "SZ-Σ90" manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7373:2006 using a test piece prepared by the method described below. The higher the value, the higher the degree of yellowness, indicating that the material is colored.

(9) Dispersed State The dispersed state was evaluated using a sheet prepared by the method described below. The state of dispersion was evaluated by visually observing one surface of the sheet. Evaluation criteria are as follows.
A: Particulate matter is not observed.
B: Granules of less than 0.5 mm are observed.
C: Granules of 0.5 mm or more are observed.

(10) Foaming properties Foaming properties were evaluated by visually observing the foam. A foam was obtained by leaving a test piece prepared by the method described below in an atmosphere of 23° C. and 50% humidity for 1 week and then placing it in an oven at 150° C. for 5 minutes. The evaluation criteria for the obtained foam are as follows.
A: Foams of 1 mm or less are uniformly formed.
B: Foaming larger than 1 mm is observed.
C: No foaming.

Each material used in the examples is as follows.
[(a) component]
[Resin (a-1)]
Styrene (ST) 71.3 parts by mass, methacrylic acid (MAA) 7.3 parts by mass, methyl methacrylate (MMA) 6.4 parts by mass, ethylbenzene 15.0 parts by mass, 1,1-bis(t-butyl per 0.025 part by mass of oxy)cyclohexane was poured at a rate of 1.1 liters/hour into a complete mixing reactor with a capacity of 4 liters and then into a laminar flow reactor with a capacity of 2 liters. and a devolatilization device connected to a single-screw extruder for removing volatile matter such as unreacted monomers and polymerization solvent, to prepare a resin.
The polymerization reaction conditions in the polymerization process were a polymerization temperature of 122° C. in the complete mixing reactor and a polymerization temperature of 120 to 142° C. in the laminar flow reactor. The devolatilized unreacted gas was condensed in a condenser through which a -5° C. refrigerant was passed, and recovered as an unreacted liquid.
The polymer content in the final polymerization liquid was measured by the formula [(sample mass after drying / sample mass before drying) x 100%] after drying the polymerization liquid for 30 minutes at 215 ° C. under a reduced pressure of 2.5 kPa. , 65.6% by mass, and the weight average molecular weight was 214,000 (214,000).
Table 1 shows the composition ratio and physical properties of the obtained resin (a-1).

[Resins (a-2) to (a-7)]
Resins (a-2) to (a-7) were obtained in the same manner as resin (a-1) by adjusting the composition, polymerization temperature conditions, etc. so that the resin properties shown in Table 1 were obtained. Table 1 shows the composition ratios and physical properties of the obtained resins (a-2) to (a-7). Maleic anhydride (MAH) was used as a monomer in resin (a-7).

[GPPS]
- Polystyrene (GPPS, PS Japan Co., Ltd., G9401) with an MFR of 2.2 was used. Physical properties are shown in Table 1.

[(b) component]
・ CNF (b-1): cellulose nanofiber (manufactured by Chuetsu Pulp Industry Co., Ltd., CNF-10, average fiber diameter 30 nm)
・ CNF (b-2): cellulose nanofiber (KY-100G manufactured by Daicel Finechem Co., Ltd., average fiber diameter: 100 nm)

[Cellulose fiber]
・ Cellulose fiber (manufactured by Celite, SW-10, average fiber diameter 25 μm)

[Additive]
(Phenolic antioxidant)
· 3-(3,5-di-tert-butyl-4-hydroxyphenyl) stearyl propionate (manufactured by BASF, Irganox 1076)
(Phosphorus antioxidant)
- Tris (2,4-di-tert-butylphenyl) phosphite (manufactured by BASF, Irgafos168)

[Examples 1 to 12]
0.2 parts by mass of Irganox 1076 and Irgafos 168 were added to 100 parts by mass of each component and components (a) to (b) in the composition ratio shown in Table 2, and then premixed. The resulting preliminary mixture is mixed together, melt-extruded at 180 ° C. to 220 ° C. using a twin-screw extruder (Toshiba Machine Co., Ltd., TEM-26SS), and pellets of the styrene resin composition are kneaded. got At this time, the screw rotation speed was 150 rpm, and the discharge rate was 10 kg/hr. Using an injection molding machine manufactured by Japan Steel Works, Ltd. equipped with an ISO standard test piece type A mold, the pellets obtained in this way are used at a cylinder temperature of 220 ° C., a mold temperature of 50 ° C., and an injection pressure (gauge pressure of 40 −60 MPa), an injection speed (panel set value) of 50%, and injection time/cooling time=5 sec/20 sec to prepare a test piece. Using the obtained test piece, the flexural modulus, Charpy impact strength and Vicat softening temperature were measured, and the surface appearance of the molded article was evaluated. For the dispersed state of nanocellulose, the obtained pellets were press-molded at 200° C. to prepare a sheet with a thickness of 0.3 mm. These evaluation results are shown in Table 2.

[Comparative Examples 1 to 11]
Comparative Examples 1 to 11 were carried out in the same manner as in Example 1, except that the compositions were changed as shown in Table 3. Table 2 shows the results of measurement and evaluation of each physical property.

As shown in Table 2, Examples 1 to 12 have improved rigidity, impact strength, and heat resistance, good CNF dispersibility, and excellent surface appearance and foaming properties.
As shown in Table 3, in the GPPS of Comparative Example 8, the dispersibility of CNF is low, the surface appearance is deteriorated, the rigidity is little improved, and the impact strength and foaming properties are deteriorated.
The micron-order cellulose fiber of Comparative Example 9 has good dispersibility, but the surface appearance is deteriorated, the rigidity is little improved, and the impact strength and foaming properties are deteriorated.
When the amount of CNF is large as in Comparative Example 10, the dispersibility of CNF is lowered, the fluidity and surface appearance are low, and the impact strength and color tone are lowered.
When a copolymer containing CNF and MAH monomer is added to GPPS as in Comparative Example 11, GPPS and the copolymer are incompatible, so CNF is unevenly distributed during the copolymerization of the domain, resulting in a decrease in dispersibility. , the property is not obtained.

Molded articles containing the resin composition of the present invention can be suitably used for building materials, electronic/electric parts, automobiles, heat insulating materials, and the like.

Claims (4)

(a) 80.0 to 99.7% by mass of a copolymer resin, and (b) 0.3 to 20.0% by mass of nanocellulose having an average fiber diameter of 3 to 200 nm. and
The (a) copolymer resin is a binary copolymer or a terpolymer, and contains styrene- based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomers. When the total content of the body units is 100% by mass, it contains 69.0 to 98.0% by mass of the styrene-based monomer unit, and the unsaturated carboxylic acid-based monomer unit is 2.0 Contains ~16.0% by mass, and contains 0.0 to 15.0% by mass of the unsaturated carboxylic acid ester-based monomer unit,
The styrenic resin composition, wherein the unsaturated carboxylic acid-based monomer unit is methacrylic acid or acrylic acid. The styrenic resin composition according to claim 1, wherein the styrenic resin composition has a melt flow rate of 0.5 g/10 minutes or more. 3. The styrenic resin composition according to claim 1, wherein the unsaturated carboxylic acid monomer of the copolymer resin (a) is methacrylic acid. A molded article comprising the styrenic resin composition according to any one of claims 1 to 3.