JP2021165378A - Styrenic resin composition and molded article - Google Patents

Abstract

To provide a styrenic resin composition excellent in optical transparency, heat resistance and appearance, and a molded article containing the styrenic resin composition.SOLUTION: The styrenic resin composition contains: a styrenic resin (a) having a refractive index of 1.545-1.600 and an MFR of 3 or more; and a cellulosic polysaccharide (b) having an average minor axis length d1 and an average major axis length d2 equal to or longer than the d1, wherein either the d1 or the d2 is 0.03-50 μm. The content of the styrenic resin (a) is 45.0-99.5 pts.mass and the content of the cellulosic polysaccharide (b) is 0.5-55.0 pts.mass based on the total amount (100 pts.mass) of the styrenic resin (a) and the cellulosic polysaccharide (b).SELECTED DRAWING: None

Description

The present invention relates to a styrene resin composition and a molded product.

Styrene-based resins are used in a wide range of applications because they are excellent in transparency in addition to moldability and dimensional stability. In addition, biomass materials are attracting attention from the viewpoint of environmental protection, and composite materials of resin materials and naturally-derived organic fillers and biopolymers are being studied.
For example, Patent Documents 1 and 2 disclose a styrene-based composite resin composition composed of a styrene-based resin and a cellulosic-based material. Further, Patent Document 3 discloses a composition composed of a styrene resin and modified nanocellulose (hereinafter, also referred to as CNF).

Japanese Unexamined Patent Publication No. 7-173352 Japanese Unexamined Patent Publication No. 8-231795 Japanese Unexamined Patent Publication No. 2016-176052

However, the techniques of Patent Documents 1 and 2 do not examine the average length of the cellulosic material used and the compatibility between the styrene resin and the cellulosic material. More specifically, in Patent Documents 1 and 2, wood powder or pulp having an average length of a minor axis or a major axis of more than 50 μm is used, and dispersion of a cellulosic material with respect to a styrene resin. Since the properties or compatibility have not been examined, the desired light transmission cannot be obtained, the appearance of the molded product is significantly deteriorated, and the products are limited. Further, in the technique of Patent Document 2, since wood powder is used as the cellulosic material, there is a problem that the composition itself is colored and the appearance and the like are deteriorated.
Further, since the technique of Patent Document 3 uses modified CNF, modification is costly, and an unreacted modifier remains in the composition, resulting in light transmission, heat resistance, and the like. There is a problem that the appearance is deteriorated.

Therefore, an object of the present invention is to provide a styrene-based resin composition having excellent light transmission, heat resistance, and appearance, and a molded product containing the styrene-based resin composition.

In view of the above problems, the present inventor has conducted extensive research and repeated experiments, and as a result, a styrene resin (a) having a refractive index of 1.545 to 1.600 and having an MFR of 3 or more and a specific size. We have found that the above problems can be solved by using a resin composition in which a cellulosic polysaccharide (b) is mixed at a specific ratio, and have completed the present invention.
That is, the present invention is as follows.

[1] The present invention comprises a styrene resin (a) having a refractive index of 1.545 to 1.600 and an MFR of 3 or more, an average length d ₁ of the minor axis, and a length d _{1 or more.} A styrene-based resin composition comprising a cellulosic polysaccharide (b) having an average shaft length d ₂ and having _{either d 1} or d _{2 of 0.03 to 50 μm.}
The content of the styrene resin (a) is 45.0 to 99.5 parts by mass with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). ,
The styrene-based resin composition is characterized in that the content of the cellulosic polysaccharide (b) is 0.5 to 55.0 parts by mass.
[2] In the present invention, it is preferable that the styrene-based resin (a) contains an unsaturated carboxylic acid-based monomer unit.
[3] In the present invention, 0.5 to 2.0 parts by mass of the dispersant (c) is added to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). It is preferable to further contain it.
[4] In the present invention, the dispersant (c) is one or more compounds selected from the group consisting of fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, and rosin compounds. Is preferable.
[5] The present invention is a molded product containing the styrene-based resin composition according to any one of the above [1] to [4].

According to the present invention, it is possible to provide a styrene-based resin composition having excellent light transmission, heat resistance, and appearance, and a molded product using the styrene-based resin composition.

FIG. 1 is a cross-sectional view of a mold used for manufacturing the container of this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following description, and various modifications are made within the scope of the gist thereof. Can be carried out.

[Styrene-based resin composition]
The styrene resin composition of the present embodiment contains the styrene resin (a) and the cellulosic polysaccharide (b), and the total amount (100) of the styrene resin (a) and the cellulosic polysaccharide (b). The styrene resin (a) is contained in an amount of 45.0 to 99.5 parts by mass and the cellulosic polysaccharide (b) is contained in an amount of 0.5 to 55.0 parts by mass. The refractive index of the styrene resin (a) is 1.545 to 1.600, and the MFR of the styrene resin (a) is 3 or more. Further, the average length of the minor axis of the cellulose-based polysaccharide (b) and d _1, when the average length d ₂ of the long axis of the cellulose, the relationship of d ₁ ≦ d ₂ is satisfied, d ₁ Alternatively _{, at least one of d 2} is 0.03 to 50 μm.

<Styrene-based resin (a) (hereinafter, also referred to as component (a))>
In the present embodiment, the content of the styrene resin (a) having a refractive index of 1.545 to 1.600 and an MFR of 3 or more is the content of the styrene resin (a) and the cellulose polysaccharide (b). It is 45.0 to 99.5 parts by mass, preferably 50.0 to 97.0 parts by mass, and more preferably 60.0 to 95.0 parts by mass with respect to the total amount (100 parts by mass). By setting the content to 45.0 parts by mass or more, light transmission and appearance can be improved. On the other hand, by setting the content to 99.5 parts by mass or less, the total content of the cellulosic polysaccharide (b) can be secured, and the rigidity, heat resistance and the like can be improved.

The refractive index of the styrene resin (a) in the present invention is 1.545 to 1.600, preferably 1.560 to 1.590, and more preferably 1.570 to 1.580. If the refractive index is lower than 1.545 or larger than 1.600, the light transmittance or the appearance of the entire styrene resin composition deteriorates. The refractive index is a value measured at 25 ° C. using an Abbe refractometer.
Further, the MFR (200 ° C., 5 kg) of the styrene resin (a) in the present invention needs to be 3 or more. It is preferably 5 or more, more preferably 8 or more and 30 or less, and further preferably 10 to 25 or less. In order to prevent coloring and burning of the cellulose (b), melt mixing at 240 ° C. or lower is required, but if the MFR is lower than 3, the cellulosic polysaccharide (b) is difficult to disperse in the styrene resin (a). Since diffuse reflection occurs at the interface between the cellulosic polysaccharide (b) and the styrene resin (a), the light transmission and appearance are deteriorated. In particular, when the cellulose (b) has a rod-like form, the styrene-based resin (a) cannot sufficiently infiltrate the bundle of the rod-shaped cellulose-based polysaccharide (b) and causes diffuse reflection at the interface, so that light transmission is exhibited. The appearance deteriorates. On the other hand, when the MFR of the styrene resin (a) is 3 or more, the cellulosic polysaccharide (b) is likely to be invaded into the aggregate of the cellulosic polysaccharide (b), and the cellulosic polysaccharide (b) is easily dispersed. Since it also invades, it has the advantage of improving light transmission and appearance.
Further, in order to improve the adhesion to the cellulosic polysaccharide (b) and further prevent diffuse reflection, the styrene resin (a) preferably contains an unsaturated carboxylic acid-based monomer unit. The content of the unsaturated carboxylic acid-based monomer unit is preferably 2.0 to 16.0% by mass, more preferably 4 to 14% by mass, still more preferably, based on the entire styrene-based resin (a). Is 8 to 13% by mass.
The styrene resin to be used may be used by blending one kind or two or more kinds, and in the case of a blended product, the refractive index and MFR are the values of the blended product.
As the refractive index in the present specification, a value measured at 25 ° C. by an Abbe refractometer is used.
As the MFR in the present specification, the value measured according to ISO 1133 is used.

The styrene-based resin (a) that can be used in the present embodiment is preferably a polymer having a styrene-based monomer unit, and more preferably a copolymer having a styrene-based monomer unit. Further, the styrene-based resin (a) is made of one or more monomers selected from the styrene-based monomer, another vinyl monomer copolymerizable with the styrene-based monomer, and a rubbery polymer. It is more preferable that the styrene-based copolymer resin obtained by polymerization is used. The styrene-based resin (a) in the present invention is not particularly limited, but for example, polystyrene, a rubber-modified styrene-based resin in which particles of the rubber-like polymer (A) are dispersed in a matrix, or a styrene-based monomer unit may be used. Examples thereof include a styrene-based copolymer resin having a rubber, or a mixture thereof.

<<polystyrene>
In the present embodiment, polystyrene is a homopolymer obtained by polymerizing a styrene-based monomer, and generally available ones can be appropriately selected and used. In addition to styrene, styrene-based monomers constituting polystyrene include α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, and ethyl. Examples include styrene, isobutylstyrene, and styrene derivatives such as t-butylstyrene or bromostyrene and inden. Styrene is particularly preferable from an industrial point of view. These styrene-based monomers can be used alone or in combination of two or more. Polystyrene does not exclude the inclusion of monomer units other than the above-mentioned styrene-based monomer units as long as the effects of the present invention are not impaired, but polystyrene is typically composed of styrene-based monomer units.

<< Rubber-modified styrene resin >>
In the present embodiment, the rubber-modified styrene resin is a resin in which particles of the rubber-like polymer (A) are dispersed in the styrene resin as a matrix, and is a styrene-based simple substance in the presence of the rubber-like polymer (A). It can be produced by polymerizing a styrene.
Examples of the styrene-based monomer constituting the rubber-modified styrene-based resin of the present embodiment include α-methylstyrene, α-methylp-methylstyrene, ο-methylstyrene, and m-methylstyrene, in addition to styrene. Examples thereof include p-methylstyrene, vinyltorene, ethylstyrene, isobutylstyrene, and t-butylstyrene or styrene derivatives such as bromostyrene and inden. In particular, styrene is preferable. These styrene-based monomers can be used alone or in combination of two or more.

The rubber-like polymer (A) contained in the rubber-modified styrene-based resin of the present embodiment may contain, for example, a styrene monomer unit-containing resin obtained from the above-mentioned styrene-based monomer inside, and / Alternatively, a styrene monomer unit-containing resin may be grafted on the outside.

As the rubber-like polymer (A), for example, polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer and the like can be used, but polybutadiene can be used. Alternatively, a styrene-butadiene copolymer is preferable. As the polybutadiene, both high cis polybutadiene having a high cis content and low cis polybutadiene having a low cis content can be used. Further, as the structure of the styrene-butadiene copolymer, both a random structure and a block structure can be used. These rubber-like polymers (A) can be used alone or in combination of two or more. Further, saturated rubber obtained by hydrogenating butadiene rubber can also be used.
Examples of such rubber-modified styrene-based resins include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (Acrylonitrile-acrylic rubber-styrene copolymer). Acrylonitrile-ethylene propylene rubber-styrene copolymer) and the like.
When the moldability of the entire styrene-based resin composition is emphasized, the styrene-based resin composition of the present embodiment contains a single amount of vinyl cyanide such as an acrylonitrile monomer unit and a methacrylonitrile monomer unit. It is preferable that the body unit is substantially not contained. Specifically, the vinyl cyanide-based monomer is preferably contained in an amount of 10% by mass or less, more preferably 5% by mass or less, and 2% by mass or less, based on the total amount of the styrene-based resin composition. It is more preferable to do so.

In the present embodiment, when the rubber-modified styrene resin is a HIPS resin, the most preferable of these rubber-like polymers (A) is high, in which cis 1,4 bonds are composed of 90 mol% or more. It is cispolybutadiene. In the high cis polybutadiene, the vinyl 1 and 2 bonds are preferably composed of 6 mol% or less, and particularly preferably 3 mol% or less.
The content of isomers having a cis 1,4, trans 1,4, or vinyl 1,2 structure as isomers related to the constituent unit of the high cis polybutadiene was measured using an infrared spectrophotometer and measured by the morero method. It can be calculated by processing the data.
Further, the high cis polybutadiene can be easily obtained by polymerizing 1,3 butadiene using a known production method, for example, a catalyst containing an organoaluminum compound and a cobalt or nickel compound.

In the present embodiment, the content of the rubber-like polymer (A) contained in the rubber-modified styrene-based resin is preferably 2 to 10% by mass, more preferably 3 by mass, based on 100% by mass of the rubber-modified styrene-based resin. ~ 8% by mass. If the content of the rubber-like polymer (A) is less than 2% by mass, the impact resistance of the styrene resin may decrease. Further, if the content of the rubber-like polymer (A) exceeds 10% by mass, the light transmittance may decrease.
In the present disclosure, the content of the rubber-like polymer (A) contained in the rubber-modified styrene resin is a value calculated by using a pyrolysis gas chromatograph.

In the present embodiment, the average particle size of the rubber-like polymer (A) contained in the rubber-modified styrene resin is preferably 0.5 to 2.5 μm, more preferably 0.5 to 2.5 μm, from the viewpoint of light transmission. It is 0.8 to 2.0 μm.
In the present disclosure, the average particle size of the rubber-like polymer (A) contained in the rubber-modified styrene resin can be measured by the following method.
An ultrathin section having a thickness of 75 nm is prepared from a rubber-modified styrene resin dyed with osmium tetroxide, and a photograph at a magnification of 10000 is taken using an electron microscope. In the photograph, the particles dyed black are rubber-like polymers. From the photo, the following formula (N1):
Average particle size = ΣniDri ³ / ΣniDri ² (N1)
(In the above formula (N1), ni is the number of rubber-like polymer (a) particles having a particle size of Dri, and the particle size Dri is a particle size calculated as a circle-equivalent diameter from the area of the particles in the photograph. .)
The area average particle size is calculated and used as the average particle size of the rubber-like polymer (A). In this measurement, a photograph is taken into a scanner at a resolution of 200 dpi and measured using particle analysis software of an image analysis device IP-1000 (manufactured by Asahi Kasei Corporation).

In the present embodiment, the reduced viscosity of the rubber-modified styrene resin (which is an index of the molecular weight of the rubber-modified styrene resin) is preferably in the range of 0.50 to 0.85 dL / g, more preferably. Is in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, the impact strength may decrease, and if it exceeds 0.85 dL / g, the moldability may decrease due to the decrease in fluidity.
In the present disclosure, the reduced viscosity of the rubber-modified styrene resin is a value measured in a toluene solution under the conditions of 30 ° C. and a concentration of 0.5 g / dL.

In the present embodiment, the method for producing the rubber-modified styrene-based resin is not particularly limited, but is a massive polymerization in which the styrene-based monomer (and the solvent) is polymerized in the presence of the rubber-like polymer (A). Or solution polymerization), massive-suspended polymerization that shifts to suspension polymerization during the reaction, or emulsified graft polymerization that polymerizes a styrene-based monomer in the presence of the rubbery polymer (A) latex. Can be done. In bulk polymerization, a mixed solution containing the rubbery polymer (a), a styrene-based monomer, and if necessary, an organic solvent, an organic peroxide, and / or a chain transfer agent is added to a complete mixed reactor. Alternatively, it can be produced by continuously supplying a tank-type reactor and a plurality of tank-type reactors to a polymerization apparatus configured by connecting them in series.

<< Styrene-based copolymer resin >>
In the present embodiment, the styrene-based copolymer resin is a resin optionally containing a styrene-based monomer unit, an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit. The styrene-based copolymer resin in the present invention has a total content of styrene-based monomer unit, unsaturated carboxylic acid-based monomer unit, and unsaturated carboxylic acid ester-based monomer unit as 100% by mass. The content of the styrene-based monomer unit is preferably 69 to 98% by mass, more preferably 74 to 96% by mass, and further preferably 77 to 92% by mass. By setting the content to 69% by mass or more, the refractive index of the styrene resin (a) can be improved. On the other hand, when the content is 98% by mass or less, it becomes difficult for the unsaturated carboxylic acid-based monomer unit and the unsaturated carboxylic acid ester-based monomer unit, which will be described later, to be present in a desired amount. It becomes difficult to obtain the effect described later by the monomer unit of.

In the styrene-based copolymer resin of the present embodiment, the unsaturated carboxylic acid-based monomer unit plays a role of improving heat resistance. 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 in the styrene-based copolymer resin is 100% by mass, the unsaturated carboxylic acid The content of the acid-based monomer unit is preferably 2 to 16% by mass, more preferably 4 to 14% by mass, and further preferably 8 to 13% by mass. By setting the content to 2% by mass or more, the dispersibility of cellulose can be improved, and the light transmittance, appearance, and heat resistance can be further improved. On the other hand, by setting the content to 16% by mass or less, the fluidity and mechanical properties of the resin can be improved.

Generally, a styrene-methacrylic acid-based resin containing a styrene-methacrylic acid-methyl methacrylate copolymer resin, which is an example of a styrene-based copolymer resin, is produced by radical polymerization in most cases on an industrial scale. In the present embodiment, in order to suppress the gelation reaction in the radical polymerization step, various alcohols can be added to the polymerization system to carry out the polymerization.

The unsaturated carboxylic acid ester-based monomer is used to suppress the dehydration reaction of the unsaturated carboxylic acid-based monomer by molecular interaction with the unsaturated carboxylic acid-based monomer, and the mechanical strength of the resin. Can be used to improve. Furthermore, the unsaturated carboxylic acid ester-based monomer also contributes to the improvement of resin properties such as weather resistance and surface hardness.

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 in the styrene-based copolymer resin of the present embodiment. The content of the unsaturated carboxylic acid ester-based monomer unit is preferably 0 to 15% by mass, more preferably 1 to 12% by mass, and further preferably 2 to 10% by mass. By setting the content to 15% by mass or less, the light transmittance and fluidity of the resin can be improved. Further, by setting the content of the unsaturated carboxylic acid ester-based monomer unit to 0% by mass, the heat resistance can be improved and the cost can be reduced. However, from the above viewpoint, the unsaturated carboxylic acid ester-based single amount The content of the body unit can be more than 0% by mass.

When an unsaturated carboxylic acid-based monomer and an unsaturated carboxylic acid ester-based monomer unit are bonded side by side, a de-alcohol reaction may occur depending on the conditions if a high-temperature, high-vacuum devolatilizer is used. Six-membered cyclic anhydride may be formed. The copolymer resin of the present embodiment may contain this 6-membered cyclic anhydride, but it is preferable that the amount of 6-membered cyclic anhydride produced is smaller because it lowers the fluidity.

In the present embodiment, the styrene monomer unit (for example, styrene monomer unit), unsaturated carboxylic acid-based monomer unit (for example, methacrylic acid monomer unit) and unsaturated in the styrene-based copolymer resin The content of the carboxylic acid ester-based monomer unit (for example, the methyl methacrylate monomer unit) can be determined from the integration ratio of the spectra measured by the ^{proton nuclear magnetic resonance (1 H-NMR) measuring machine.} ..

In the present embodiment, the styrene-based copolymer resin is a monomer unit other than the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit which is an optional component. Is not excluded as long as the effect of the present invention is not impaired. However, the copolymer resin in the present invention is typically preferably composed of a styrene-based monomer unit, an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit. ..

The styrene-based monomer constituting the styrene-based copolymer resin of the present embodiment is not particularly limited as the styrene-based monomer, but for example, styrene, α-methylstyrene, α-methyl-p-methylstyrene, and the like. Examples thereof include styrene derivatives such as ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene and inden. As the styrene-based monomer, styrene is preferable from an industrial point of view. These styrene-based monomers can be used alone or in combination of two or more.

The unsaturated carboxylic acid-based monomer constituting the styrene-based copolymer resin of the present embodiment is not particularly limited, and examples thereof include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, and itaconic acid. Be done. As the unsaturated carboxylic acid-based monomer, methacrylic acid is preferable because it has a large effect of improving heat resistance, is liquid at room temperature, and has excellent handleability. These unsaturated carboxylic acid-based monomers can be used alone or in combination of two or more.

The unsaturated carboxylic acid ester-based monomer constituting the styrene-based copolymer resin of the present embodiment is not particularly limited, and is, for example, methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , Butyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. As the (meth) acrylate-based monomer, methyl (meth) acrylate is preferable because it has a small effect on the decrease in heat resistance. These unsaturated carboxylic acid ester-based monomers can be used alone or in combination of two or more.
Examples of the styrene-based copolymer resin of the present embodiment include a styrene-methyl acrylate copolymer, a styrene-ethyl ethyl acrylate copolymer, a styrene-propane acrylate copolymer, or styrene. − (Meta) butyl acrylate copolymer, styrene-methyl (meth) acrylate-meth) butyl acrylate copolymer, and styrene-methyl (meth) acrylate-methacrylic acid copolymer are preferable.

In the present embodiment, the weight average molecular weight (Mw) of the styrene-based copolymer resin is preferably 100,000 to 350,000, more preferably 120,000 to 300,000, still more preferably 140,000 to 240. It is 000. When the weight average molecular weight (Mw) is 100,000 to 350,000, a resin having an excellent balance between mechanical strength and fluidity can be obtained, and gels are less mixed. The weight average molecular weight (Mw) is a value obtained in terms of standard policelene by using gel permeation chromatography.
As the styrene resin (a) of the present embodiment, a mixture of one or more of the above rubber-modified styrene resins and one or more of the styrene copolymer resins may be used. good. In that case, the mixing ratio of the rubber-modified styrene resin and the styrene copolymer resin can be appropriately changed according to the purpose of use. For example, in a system in which the amount of rubber-modified styrene resin is less than that of the styrene copolymer resin, the styrene copolymer resin is contained in an amount of 0.1 to 30% by mass based on the total amount (100% by mass) of the styrene resin (a). It is preferable to do so. On the other hand, in a system in which the amount of the rubber-modified styrene resin is larger than that of the styrene copolymer resin, the styrene copolymer resin is contained in an amount of 70 to 99.9% by mass based on the total amount (100% by mass) of the styrene resin (a). It is preferable to do so.
As the styrene resin (a) of the present embodiment, one or more homopolymers (polystyrene) obtained by polymerizing a styrene monomer and one or more styrene copolymer resins are blended. The mixture may be used. In that case, the mixing ratio of the homopolymer and the styrene-based copolymer resin can be appropriately changed according to the purpose of use. For example, in a system in which the amount of the homopolymer is less than that of the styrene-based copolymer resin, the styrene-based copolymer resin is contained in an amount of 0.1 to 30% by mass based on the total amount (100% by mass) of the styrene-based resin (a). Is preferable. On the other hand, in a system in which the amount of the homopolymer is larger than that of the styrene-based copolymer resin, the styrene-based copolymer resin is contained in an amount of 70 to 99.9% by mass based on the total amount (100% by mass) of the styrene-based resin (a). Is preferable.
As described above, as the styrene resin (a), a specific amount (composition) of a blend of a homopolymer (polystyrene) and a styrene copolymer resin or a blend of a rubber-modified styrene resin and a styrene copolymer resin is used. When used (about 60% by mass with respect to the whole), the moldability of the composition as a whole, particularly the spreadability, is improved. Further, when a predetermined amount of liquid paraffin is added as an additive, the moldability of the composition as a whole, particularly the malleability, is further improved.

In the present embodiment, the polymerization method of the styrene-based copolymer resin is not particularly limited, but for example, a massive polymerization method or a solution polymerization method can be preferably adopted as the radical polymerization method. The polymerization method mainly includes a polymerization step of polymerizing a polymerization raw material (monomer component) and a devolatilization step of removing volatile components such as unreacted monomer and polymerization solvent from the polymerization product.

Hereinafter, an example of a polymerization method of the styrene-based copolymer resin that can be used in the present embodiment will be described.
When the polymerization raw material is polymerized in order to obtain the styrene-based copolymer resin, the polymerization raw material composition typically contains a polymerization initiator and a chain transfer agent.
Examples of the polymerization initiator used for the polymerization of the styrene-based copolymer resin include organic peroxides such as 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, and n. Peroxyketals such as -butyl-4,4-bis (t-butylperoxy) valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, acetylperoxide, isobutylyl Diacyl peroxides such as peroxide, peroxydicarbonates such as diisopropylperoxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, hydroperoxides such as t-butylhydroperoxide, etc. be able to. From the viewpoint of decomposition rate and polymerization rate, 1,1-bis (t-butylperoxy) cyclohexane is particularly preferable.
Examples of the chain transfer agent used for the polymerization of the styrene-based copolymer resin include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan.

As a method for polymerizing the styrene-based copolymer resin, solution polymerization using a polymerization solvent can be adopted, if necessary. Examples of the polymerization solvent used include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone, which may be used alone or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed with aromatic hydrocarbons as long as the solubility of the polymerization product is not reduced. It is preferable to use these polymerization solvents in a range not exceeding 25 parts by mass with respect to 100 parts by mass of all the monomers. When the amount of the polymerization solvent exceeds 25 parts by mass with respect to 100 parts by mass of all the monomers, the polymerization rate tends to be remarkably lowered, and the mechanical strength of the obtained resin tends to be greatly lowered. Before polymerization, it is preferable to add 5 to 20 parts by mass with respect to 100 parts by mass of all the monomers because the quality can be easily made uniform and the polymerization temperature can be controlled.

In the present embodiment, the apparatus used in the polymerization step for obtaining the styrene-based copolymer resin is not particularly limited and may be appropriately selected according to the polymerization method of the styrene-based resin. For example, when bulk polymerization is adopted, a polymerization apparatus in which one or a plurality of completely mixed reactors are connected can be used. In addition, there are no particular restrictions on the volatilization process. For example, when bulk polymerization is adopted, the polymerization is finally advanced until the unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and the volatile components of the unreacted monomer or the like are removed. In addition, the volatilization treatment is carried out by a known method. More specifically, for example, a normal volatilizer such as a flash drum, a twin-screw volatilizer, a thin film evaporator, or an extruder can be used, but a volatilizer having a small retention portion is preferable. The temperature of the devolatilization treatment is usually about 190 to 280 ° C., more preferably 190 to 260 ° C. from the viewpoint of suppressing the formation of a six-membered cyclic 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, and more preferably 0.13 to 2.0 kPa. As the devolatile method, for example, a method of removing volatile matter by reducing the pressure under heating and a method of removing volatile matter through an extruder designed for the purpose of removing volatile matter are desirable.

<Cellulose-based polysaccharide (b) (hereinafter, also referred to as component (b))>
Cellulosic polysaccharides in this embodiment (b) is provided with an average length of the minor axis represented by d _1, and the average length of the major axis represented by d _2, the average length d ₂ of the long shaft, The condition is satisfied that the average length d ₁ or more of the minor axis _{and either the average length d 1} of the minor axis or the average length d ₂ of the major axis is in the range of 0.03 to 50 μm. The content of the cellulosic polysaccharide (b) in the present invention is 5 to 55.0 parts by mass with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). It is preferably 10 to 50 parts by mass, more preferably 15 to 40.0 parts by mass. By setting the content of the component (b) to 5 parts by mass or more, the mechanical strength can be improved. On the other hand, if the content is too large, the light transmittance is lowered and the moldability is remarkably lowered due to the lowered fluidity. The content of the cellulosic polysaccharide (b) in the composition is determined by dissolving the styrene resin composition in a solvent in which the styrene resin (a) dissolves, as described in the column of Examples described later, and undissolved the styrene resin composition. It can be calculated by measuring the mass of the product taken out and dried at 120 ° C. for 4 hours.

_{In the present embodiment, at least one of the average length d 1} of the minor axis and the average length _{d 2} of the major axis of the cellulosic polysaccharide (b) is 0.03 to 50 μm, preferably 0.05 to 0.05. It is 30 μm, preferably 0.1 to 30 μm, and more preferably 0.2 to 20 μm. If the average length of the minor axis and the major axis is out of the above range, light transmission or rigidity may not be sufficiently exhibited, or impact resistance and molded appearance may be deteriorated. On the other hand, when the average lengths of the minor axis and the major axis are within the above range, the aggregation of the celluloses can be reduced, the dispersibility in the styrene resin (a) is improved, and the light transmittance is improved. In the cellulosic polysaccharide (b) of the present embodiment, the average length d ₁ of the minor axis is equal to or less than the average length d ₂ of the major axis, and the average length d ₁ of the minor axis is the major axis. It is preferable that the average length of d _{is less than 2.}
In the present invention, the average length d ₁ of the minor axis of the cellulosic polysaccharide (b) is the minor axis length of 100 cellulosic polysaccharides (b) as observed by transmission electron microscopy (magnified 5000 times). It is obtained by measuring (minimum length) and taking the arithmetic average. On the other hand, the average length of the long axis of cellulose is obtained by measuring the long axis length (maximum length) of 100 cellulosic polysaccharides (b) by observation with a transmission electron microscope (5000 times) and taking the arithmetic mean thereof. It is required by. Further, the average length d ₁ of the minor axis of the cellulosic polysaccharide (b) is obtained by measuring the minor axis length (minimum length) of the cellulosic polysaccharide (b) in the same manner as the average length of the major axis. Be done. The minor axis length (minimum length) of the cellulosic polysaccharide (b) refers to the length of the thinnest (or shortest) portion on the image, and the major axis length (maximum length) of the cellulosic polysaccharide (b). Refers to the length of the longest part on the image. Light transmission is affected by the shape of the cellulose, and in the case of fibers, the minor axis, scaly or granular ones are affected by the average diameter of the major axis.
The shape of the cellulosic polysaccharide (b) in the present invention is not particularly limited, and examples thereof include a spherical shape, an irregular shape, a powder shape, a scaly shape, a fibrous shape, and a rod shape.
The aspect ratio (d 1 / d ₂ ) of _{the average length d 1 on the minor axis and the average length d 2} on the major axis of the cellulosic polysaccharide (b) in the present invention _{is preferably 1 to 500.} It is more preferably 1.2 to 300, further preferably 1.5 to 200, and particularly preferably 2 to 100.

The cellulosic polysaccharide (b) in the present invention refers to a polysaccharide having a β-1,4-glucan structure, and includes cellulose and hemicellulose. The material of the cellulosic polysaccharide (b) is not particularly limited as long as the fibers constituting the cellulosic polysaccharide (b) are formed of a polysaccharide having a β-1,4-glucan structure. , For example, cellulose fibers derived from higher plants [for example, wood fibers (wood pulps such as conifers and broadleaf trees), bamboo fibers, sugar cane fibers, seed hair fibers (cotton linters, bombax cotton, capoc, etc.), ginseng fibers (eg, cotton linters, bombax cotton, capoc, etc.) For example, natural cellulose fibers (pulp fibers) such as hemp, kozo, mitsumata, etc.), leaf fibers (for example, Manila hemp, New Zealand hemp, etc.), animal-derived cellulose fibers (soy cellulosic, etc.), bacterial-derived cellulose fibers, chemicals. Cellulose fibers synthesized as [cellulose acetate (cellulose acetate), cellulose propionate, cellulose butyrate, cellulose acetate propionate, organic acid esters such as cellulose acetate butyrate; cellulose nitrate, cellulose sulfate, cellulose phosphate, etc. Inorganic acid ester; mixed acid ester such as cellulose nitrate acetate; hydroxyalkyl cellulose (eg, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, etc.); carboxyalkyl cellulose (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl cellulose (methyl cellulose, etc.) , Ethyl cellulose, etc.); Cellulose derivative fibers such as regenerated cellulose (rayon, cellophane, etc.)] and the like. The fibers constituting these cellulosic polysaccharides (b) may be used alone or in combination of two or more.

Among the fibers constituting the cellulosic polysaccharide (b), the production efficiency is high from the viewpoint of dispersibility, rigidity, and impact resistance when the cellulosic polysaccharide (b) is produced, and the fiber diameter and fiber length are appropriate. From this point of view, plant-derived cellulose fibers, for example, pulp-derived cellulose fibers such as wood fibers (coniferous trees, broad-leaved trees, wood pulps such as bamboo) and seed hair fibers (cotton linter pulp, etc.) are preferable.
In the present embodiment, the content of lignin in 100% by mass of the cellulosic polysaccharide (b) is preferably 10% by mass or less, and more preferably 5% by mass or less. If the content of lignin is more than 10% by mass with respect to the total amount of the cellulosic polysaccharide (b), the odor and coloring will increase during heat processing, and the lignin deteriorated product will become charcoal-like black spots and the product value will decrease. In addition, in the case of food containers, it may cause holes when heating in a microwave oven.
Further, in the present embodiment, hemicellulose is preferably contained in an amount of 1% by mass or more based on 100% by mass of the cellulosic polysaccharide (b). By containing hemicellulose, the dispersibility with the styrene resin (a) is improved, and the light transmittance, rigidity, and molded appearance can be improved. In the present invention, it is preferable that these components are not completely removed in the process of producing cellulose, but are left in a content within a suitable range. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and plays a role of hydrogen bonding with cellulose to connect microfibrils. Further, since the solubility parameter (SP value) of hemicellulose is on the hydrophobic side with respect to cellulose, hemicellulose has the effect of alleviating the SP value difference between the styrene resin (a) and the cellulosic polysaccharide (b). It is considered to have. The amount of hemicellulose can be adjusted by reducing the amount of hemicellulose to a desired amount by subjecting a natural wood raw material having a high hemicellulose content to a desired amount, or when a raw material having a low hemicellulose content is used, the amount of hemicellulose can be adjusted. It can be adjusted to a desired amount by adding hemicellulose obtained by extraction treatment from another raw material. At this time, the structure such as the end of hemicellulose may be partially different from the natural product by purification or extraction treatment.
In the present embodiment, hemicellulose is 1 with respect to the cellulose-based polysaccharide (b) (100% by mass) for the purpose of alleviating the SP value difference between the styrene-based resin (a) and the cellulose-based polysaccharide (b). It is more preferably contained in an amount of 5% by mass or more and 25% by mass or less, further preferably 2% by mass or more and 20% by mass or less, further preferably 3% by mass or more and 20% by mass or less, and 5% by mass or more and 19.5% by mass. It is even more preferably contained in an amount of 7% by mass or more and 19.3% by mass or less.
The crystallinity of the cellulosic polysaccharide (b) in the present embodiment is preferably 50 to 100%, more preferably 60 to 90%, and even more preferably 70 to 85%. The crystallinity of the cellulosic polysaccharide (b) in the present specification can be calculated by an X-ray diffraction method. Specifically, after placing the cellulosic polysaccharide (b) or a sample containing the cellulosic polysaccharide (b) on a glass cell, the Segal method (for example, "L") is performed using an X-ray diffraction measuring device. . Segal, JJ Creery, AE Martin, Jr., andCM Conrad, Text. Res. J., 29,786 (1959) ”). In the obtained X-ray diffraction results, after the diffraction intensity of 2θ = 10 ° to 30 ° was used as the baseline, the diffraction intensity of the (200) plane of 2θ = 22.6 ° and the amorphous phase of 2θ = 18.5 °. It is calculated by the following formula (1) from the diffraction intensity of.
Crystallinity (%) = [(I ₍₂₀₀₎ −I) / I ₍₂₀₀₎ ] × 100 Formula (1) (In the above formula (1), I ₍₂₀₀₎ is the diffraction intensity of the (200) plane (200). 2θ = 22.6 °), and I represents the diffraction intensity of the amorphous phase (2θ = 18.5 °).

<Dispersant (c) (hereinafter, also referred to as component (c))>
In the present embodiment, for the purpose of improving the dispersibility of cellulose, the dispersant (c) is added to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). It may be contained in an amount of 5 to 20 parts by mass, more preferably 0.8 to 17 parts by mass, and further preferably 0.8 to 11 parts by mass. From another viewpoint, the dispersant (c) is contained in an amount of 0.5 to 2 parts by mass with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). It is also preferable, and more preferably 0.8 to 18 parts by mass, still more preferably 0.8 to 10 parts by mass. By adding the dispersant (c) to the styrene-based resin composition, the extruder used when combining the cellulose fiber (b) and the styrene-based resin (a) is burnt or rheumatized (so-called molten resin). Waste) can be prevented and the molding appearance can be further improved. If the amount of the dispersant is less than the predetermined amount, a large effect cannot be expected, and if the amount is more than the predetermined amount, it is difficult to obtain a large heat resistance. A dispersant having an excellent affinity for the styrene resin (a) tends to show a greater effect.

In the present embodiment, as the dispersant (c), a fatty acid ester-based compound, a polyethylene glycol-based compound, a terpene-based compound, a rosin-based compound, a fatty acid amide, a fatty acid-based compound, a fatty acid metal salt-based compound, or the like can be used. In particular, as the dispersant (c), one or more compounds selected from the group consisting of fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, and rosin compounds are preferable.
Examples of the aliphatic ester compound include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, and palmitin. Isopropyl acid, octyl palmitate, octyl coconut fatty acid ester, octyl stearate, octyl stearate, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, linear with 28-30 carbon atoms and no branching Saturated monocarboxylic acid (hereinafter abbreviated as montanic acid) and ethylene glycol ester, montanic acid and glycerin ester, montanic acid and butylene glycol ester, montanic acid and trimethylolethane ester, montanic acid and trimethylpropane ester , Montaneic acid and pentaerythritol ester, glycerin monostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitans squilate, sorbitan triolate, polyoxyethylene sorbitan monolaurate, Examples thereof include polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan triolate. These may be used alone or in combination of two or more.
The polyethylene glycol-based compound is not particularly limited, and for example, polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, etc. Polyethylene glycol alkylaryl ethers, polypropylene glycol alkylaryl ethers, polyethylene glycol glycerin esters, polypropylene glycol glycerin esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycolized ethylenediamines, polypropylene glycolated ethylenediamines, polyethylene glycol Examples thereof include diethylenetriamine chemicals and diethylenetriamines obtained from polypropylene glycol.

The terpene-based resin is usually obtained by copolymerizing a terpene monomer alone, a terpene monomer and an aromatic monomer, or a terpene monomer and phenols in the presence of a Friedercraft type catalyst in an organic solvent. However, the resin is not limited to these. Examples of the terpene monomer include hemiterpenes having 5 carbon atoms such as isoprene, α-pinene, β-pinene, dipentene, d-lymonen, milsen, aloosimene, osimene, α-ferrandrene, α-terpinene, and γ-terpinene. , Terpineol, 1,8-cineol, 1,4-cineol, α-terpineol, β-terpineol, γ-terpineol, sabinene, paramentadiens, curenes and other monoterpenes with 10 carbon atoms, cariophyllene, longifolene, etc. Examples thereof include, but are not limited to, sesquiterpenes having 15 carbon atoms and diterpenes having 20 carbon atoms. Among these compounds, α-pinene, β-pinene, dipentene, and d-limonene are particularly preferably used. Examples of the aromatic monomer include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, isopropenyltoluene and the like. Further, examples of the phenols include, but are not limited to, phenol, cresol, xylenol, bisphenol A and the like.
Further, the hydrogenated terpene resin obtained by hydrogenating the obtained terpene resin may be used. For example, preferable terpene-based resins include terpene-based resins such as α-pinene resin, β-pinene resin, aromatic-modified terpene resin, terpene phenol resin, and hydrogenated terpene resin. The terpene resin may be used alone or in combination of two or more.

Examples of the rosin-based resin include rosins such as gum rosin, wood rosin, and tall oil rosin, stabilized rosin obtained by disproportionate or hydrogenating the rosin, and polymerized rosin which is a multimer of the rosin (typically). Is a dimer), modified rosin modified with unsaturated acids such as maleic acid, fumaric acid, and (meth) acrylic acid. Examples of the rosin derivative resin include esterified products of the rosin-based resin, phenol-modified products, and esterified products thereof. The rosin-based resin may be used alone or in combination of two or more. The rosin-based resin or rosin derivative resin used in the present invention is not limited to these resins.

Examples of the aliphatic amide include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, and ethylene bislauric acid amide. .. These may be used alone or in combination of two or more.

Specific examples of the saturated fatty acids among the above fatty acid compounds include lauric acid (dodecanoic acid), isodecanoic acid, tridecic acid, myristic acid (tetradecanoic acid), pentadecic acid, palmitic acid (hexadecanoic acid), and margaric acid (heptadecanoic acid). Acid), stearic acid (octadecanoic acid), isostearic acid, tubercrostearic acid (nonadecanic acid), 2-hydroxystearic acid, arachidic acid (icosanoic acid), behenic acid (docosic acid), lignoseric acid (tetradocosanoic acid), cellotin Acids (hexadocosanoic acid), montanic acid (octadocosanoic acid), melisic acid and the like can be mentioned, and in particular, lauric acid, palmitic acid, stearic acid, bechenic acid, 12-hydroxystearic acid and montanic acid and the like can be mentioned. These may be used alone or in combination of two or more.

Specific examples of the unsaturated fatty acid among the above fatty acid compounds include myristoleic acid (tetradecenoic acid), palmitoleic acid (hexadecenoic acid), oleic acid (cis-9-octadecenoic acid), and elaidic acid (trans-9-). Octadecenoic acid), ricinolic acid (octadecadienoic acid), baxenoic acid (cis-11-octadecenoic acid), linoleic acid (octadecadienoic acid), linolenic acid (9,11,13-octadecatrienoic acid), elestea Acids (9,11,13-octadecatrienoic acid), gadrainic acid (icosanoic acid), erucic acid (docosanoic acid), nervonic acid (tetradocosanoic acid) and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the fatty acid metal salt include lithium salt, calcium salt, magnesium salt, zinc salt, aluminum salt and the like of the fatty acid of the above fatty acid compound. These may be used alone or in combination of two or more.

<Arbitrary additive component>
In the styrene resin composition of the present embodiment, in addition to the above components (a) to (c), additional components such as known additives and processing aids are required as long as the effects of the present invention are not impaired. Can be added. Examples of these additives, processing aids and the like include antioxidants, weathering agents, antistatic agents, fillers, liquid paraffin and the like.

Examples of the antioxidant include phenolic compounds, phosphorus compounds, thioether compounds and the like.
Examples of the phenolic antioxidant include 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, and distearyl (3,5-di-tert-butyl). -4-Hydroxybenzyl) phosphonate, 1,6-hexamethylenebis [(3,5-di-tertbutyl-4-hydroxyphenyl) propionic acid amide], 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-sec-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-hydroxyphenyl) propionate], bis [3,3-bis (4-hydroxyphenyl) propionate] Hydroxy-3-tert-butylphenyl) butyric 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] and the like. These may be used alone or in admixture of two or more.

Examples of the phosphorus-based antioxidant include tris (2,4-di-tert-butylphenyl) phosphite, trisnonylphenyl phosphite, and 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-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) isopropylidene diphenol 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) butanetriphosphite, 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-tetrakiss-tert-) Butyldibenzo [d, f] [1,3,2] dioxaphosfepin-6-yl) oxy] ethyl) amine, 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert- Examples include butylphenol phosphite. These may be used alone or in admixture of two or more.

Examples of the thioether-based antioxidant include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra (β-alkyl mercaptopropionic acid ester). These may be used alone or in admixture of two or more.

As the weather resistant agent, an ultraviolet absorber such as a hindered amine light stabilizer can be used. Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 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- Chlorobenzotriazol, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazol, 2- (2'-hydroxy-5'
-Tert-octylphenyl) benzotriazol, 2- (2'-hydroxy-3', 5'-dicumylphenyl) benzotriazol, 2,2'-methylenebis (4-tert-octyl-6- (benzotoria) 2- (2'-Hydroxyphenyl) benzotriazoles such as zoryl) phenol), 2- (2'-hydroxy-3'-tert-butyl-5'-carboxyphenyl) benzotriazole; phenylsalicylate, 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- Hydroxybenzoates, benzoates such as hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; substitutions such as 2-ethyl-2'-ethoxyoxanilide, 2-ethoxy-4'-dodecyloxanilide, etc. Oxanilides; cyanoacrylates such as ethyl-α-cyano-β, β-diphenyl acrylate, 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, Examples thereof include triaryltriazines such as 2- (2-hydroxy-4-propoxy-5-methylphenyl) -4,6-bis (2,4-di-tert-butylphenyl) -s-triazine. These may be used alone or in admixture of two or more.

Examples of the hindered amine-based light stabilizer include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2. 6,6-Tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-tetramethyl-4-piperidyl) Sevacate, Bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) Sevacate, Tetrakiss (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4 -Butan 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-butanetetracarboxylate, bis (1,2,2,4,4-pentamethyl-4-piperidyl) -2-butyl-2- (3,5-dith butyl-4-hydroxybenzyl) ) Malonate, 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-piperidinol / diethyl polycondensate succinate, 1,6-bis (2,2,6,6-) Tetramethyl-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-third octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis [2,4-bis (N-butyl-N- (2,2,6)) 6-Tetramethyl-4-piperidyl) amino) -s-triazine-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-triazine-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-triazine-6-yl] aminoundecane, 1,6 11-Tris [2,4-bis (N-butyl-N- (1,2,2) , 6,6-Pentamethyl-4-piperidyl) amino) -s-triazine-6-yl] Hindered amine compounds such as aminoundecane can be mentioned. These may be used alone or in admixture of two or more.

As the antistatic agent, fatty acid partial esters such as cationic type, anion type, nonionic type, amphoteric type, and glycerin fatty acid monoester can be used.
Specifically, alkyltrimethylammonium salt, dialkyldimethylammonium salt, benzalconium salt, N, N-bis (2-hydroxyethyl) -N- (3-dodecyloxy-2-hydroxypropyl) methylammonium mesosulfate. , (3-laurylamide propyl) trimethylammonium methyl sulfate, stearoamide propyldimethyl-2-hydroxyethylammonium nitrate, stearoamide propyldimethyl-2-hydroxyethylammonium phosphate, cationic polymer, alkyl sulfonate , Alkylbenzene sulfonate, alkyl diphenyl ether disulfonate sodium, alkyl nitrate ester salt, phosphoric acid alkyl ester salt, alkyl phosphate amine salt, stearic acid monoglyceride, pentaerythritol fatty acid ester, sorbitan monopalmitate, sorbitan monostearate, diglycerin fatty acid Estel, Alkyl Diethanolamine, Alkyl Diethanolamine Fatty Acid Monoester, Alkyl Diethanolamide, Polyoxyethylene Dodecyl Ether, Polyoxyethylene Alkylphenyl Ether, Polyethylene Glycol Monolaurate, Polyoxyethylene Alkamine, Polyoxyethylene Alkamide, Polyether Block Copolymer , Cetyl betaine, hydroxyethyl imidazoline sulfate ester and the like. These may be used alone or in admixture of two or more.

As the filler, talc, calcium carbonate, barium sulfate, carbon fiber, mica, wallastnite, whiskers and the like can be used.
In addition, anti-blocking agents, colorants, anti-blooming agents, surface treatment agents, antibacterial agents, anti-eye tars (silicone oils described in Japanese Patent Application Laid-Open No. 2009-120717, monoamide compounds of higher aliphatic carboxylic acids, and higher fats. An inhibitor) or the like may be added to the eyes such as a monoester compound obtained by reacting a group carboxylic acid with a monovalent to trivalent alcohol compound.
The liquid paraffin is also referred to as mineral oil, and is an oligomer or polymer containing paraffinic hydrocarbons. The liquid paraffin contains paraffin-based oil, naphthen-based oil, and paraffin wax, and is a mixture of paraffin hydrocarbon and alkylnaphthene hydrocarbon. Those having a specific density of 0.8494 or less at 15 ° C. and those having a specific gravity of more than 0.8494 at 15 ° C. are included. The naphthenic content of the liquid paraffin is preferably 15% by mass or more and 55% by mass or less, and more preferably 20% by mass or more and 45% by mass or less with respect to 100% by mass of the liquid paraffin. It is more preferably 19% by mass or more and 35% by mass or less.
The content of the liquid paraffin is 0.07 parts by mass or more and 5 parts by mass or less with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). It is preferably 0.15 parts by mass or more and 2.8 parts by mass or less.

The total content of the optional additive components such as the additive and the processing aid may be 0.05 to 5% by mass in the styrene resin composition.

The styrene-based resin composition of the present embodiment may be substantially composed of only the components (a) to (c) and the optional additive components. Further, it may consist of only the components (a) to (c), or only the components (a) to (c) and the optional additive components.
"Substantially composed of only the components (a) to (c) and the optional additive component" means that 95 to 100% by mass (preferably 98 to 100% by mass) of the styrene resin composition is the component (a). It means that it is a component (c) or a component (a) to (c) and an optional additive component.
The styrene-based resin composition of the present embodiment may contain unavoidable impurities in addition to the components (a) to (c) and optional additives as long as the effects of the present invention are not impaired.

[Physical characteristics of styrene resin composition]
<Light transmission>
The light transmittance of the molded product obtained from the styrene resin composition of the present embodiment is preferably 60% or more, more preferably 70% or less, with a total light transmittance of 1 mm in thickness. If it is lower than 60%, it is difficult for light to pass through, and visibility and design are inferior. In the present disclosure, the light transmittance is a value measured according to the method for measuring the total light transmittance of JIS K7361.

<Heat shrinkage rate>
The heat shrinkage of the molded product obtained from the styrene resin composition of the present embodiment is preferably 20% or less, more preferably 10% or less under an atmosphere of 120 ° C. for 30 minutes. If it exceeds 20%, the product may be deformed.

<Ductility>
The spreadability of the styrene-based resin composition of the present embodiment refers to the ratio of the thickness of the bottom side wall / the thickness of the top side wall of the container when the container is formed at a predetermined drawing ratio. It is preferable that a container having a drawing ratio of 0.5 or more can be obtained by vacuum forming from a sheet body which is a molded product formed from the styrene resin composition of the present embodiment. The spreadability in the present embodiment is preferably such that the ratio of the thickness of the bottom side wall / the thickness of the top side wall is 1 to 0.3 after vacuum forming a container having a drawing ratio of 0.5.
As an example of the molded body of the present embodiment, the molding of the container will be described with reference to FIG. FIG. 1 is a cross-sectional view of a mold 1 required for molding a container. Further, FIG. 1 shows, as an example, a state in which a spacer 2 having a height of 80 cm is placed on the bottom of the mold 1. The height of the spacer 2 can be appropriately adjusted according to the desired container height.
For example, as a method for producing a container of the present embodiment, it can be produced according to the following procedures (I) and (II). (I) A sheet body of the styrene resin composition is produced by extrusion molding the styrene resin composition prepared with a predetermined composition. (II) After that, the sheet body of the obtained styrene resin composition is preheated at 150 to 250 ° C. for 5 to 60 seconds, and then the heated sheet body is covered with the recess of the mold 1 (that is, an opening). Install (covering the part) and shape by a predetermined molding method. For example, by creating a vacuum inside the recess, it can be shaped into a container having a desired shape.
Further, after the sheet body is installed so as to cover the concave portion of the mold 1, it may be heated and shaped by a predetermined molding method (for example, thermal pressure molding, vacuum forming, pressure molding, plug assist molding).
As an example of a preferred embodiment of the present embodiment, the container is formed by hot-press molding, vacuum forming, pressure-pneumatic molding, or plug-assist molding of a heated styrene resin composition sheet using a mold 1. Can be shaped.
Further, when manufacturing a container, the spacer 2 is used to measure the diameter of the upper surface of the concave portion of the mold 1 (= the diameter of the opening (φ80 cm as an example in FIG. 1)) and the depth of the concave portion of the mold 1 (in FIG. 1). As an example, the aperture ratio, which is a ratio of 40 cm), can be changed. FIG. 1 shows, as an example, a state in which a spacer 2 having a height of 80 cm is provided in a recess having a depth of 120 cm. The aperture ratio is expressed by the following mathematical formula (2).
Aperture ratio = height of container ÷ diameter of opening of container Formula (2)

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

[Molding]
The molded product of the present invention is characterized by containing the above-mentioned styrene-based resin composition.
The styrene-based resin composition of the present embodiment is an injection molding method, an injection compression molding method, an extrusion molding method, or a blow molding using the above-mentioned melt-kneading molding machine or using the obtained pellets of the styrene-based resin composition as a raw material. A molded product can be manufactured by a method, a press molding method, a vacuum molding method, a foam molding method, or the like.

The molded product containing the styrene resin composition of the present embodiment, preferably the injection molded product (including injection compression), is an OA of a copier, a fax machine, a personal computer, a printer, an information terminal, a refrigerator, a vacuum cleaner, a microwave oven, or the like. It is suitably used for equipment, household appliances, housings and various parts of electrical and electronic equipment, interior and exterior members of automobiles, construction materials, foam insulation materials, insulating films, and the like.

Hereinafter, embodiments of the present invention will be described in more detail 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 each Example and Comparative Example were measured and evaluated based on the following methods.
(1) Content of styrene monomer unit, methacrylic acid monomer unit, and methyl methacrylate monomer unit in styrene resin (a) ^{Measured with a proton nuclear magnetic resonance (1} H-NMR) measuring machine. The resin composition was quantified from the integral ratio of the spectrum.
Sample Preparation: 4-6 resin pellets 30mg at 60 ° C. in _d 6-DMSO 0.75 mL
Heat-dissolved for hours.
・ Measuring equipment: JNM ECA-500 manufactured by JEOL Ltd.
- Measurement conditions: measurement temperature 25 ℃, observing nucleus ¹ H, integration number 64 times, repetition time 11 seconds.

(Spectral attribution)
Regarding the attribution of the spectrum measured in dimethylsulfoxide heavy solvent, the peak of 0.5 to 1.5 ppm is the peak derived from hydrogen of the α-methyl group of methacrylic acid, methyl methacrylate, and 6-membered cyclic acid anhydride. The peak of 1.6 to 2.1 ppm is the peak derived from hydrogen of the methylene group of the polymer main chain, and the peak of 3.5 ppm is the peak derived from hydrogen of the carboxylic acid ester (-COOCH ₃ ) of methyl methacrylate, 12.4 ppm. The peak is a hydrogen-derived peak of the carboxylic acid of methacrylic acid. The peak of 6.5 to 7.5 ppm is a peak derived from hydrogen in the aromatic ring of styrene. In addition, since the content of the six-membered cyclic acid anhydride is small in the resins of this example and the comparative example, it is usually difficult to quantify by this measurement method.

(2) Weight average molecular weight of the styrene resin (a) The weight average molecular weight of the styrene resin (a) was measured under the following conditions and procedures.
-Sample preparation: The resin was dissolved in tetrahydrofuran in an amount of about 0.05% by mass.
-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 standard PS made by TOSOH.

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

(4) Refractive index The refractive index is a value measured at 25 ° C. using an Abbe refractometer.

(5) Total light transmittance The total light transmittance (%) was measured according to JIS K7361 using the test piece (b) prepared by the method described later.

(6) Heat shrinkage rate The heat shrinkage rate (%) is measured in the length direction after being left in an oven at 120 ° C. for 30 minutes using the test piece (a) prepared by the method described later. And the shrinkage rate was determined.

(7) Surface appearance As for the surface appearance, observe one surface of the test piece (b) prepared by the method described later, and if there are less than 20 dents with an opening of 0.1 mm or more, "Pass: ○". , And the case where 20 or more were present was evaluated as “defective; ×”.

(8) Spreadability Using a pellet-shaped styrene resin composition as a raw material by the method described later, a container having a drawing ratio of 0.5 is vacuum-formed using the mold 1 of FIG. 1, and the thickness of each part of the container is confirmed. The spreadability was evaluated according to the following criteria.
Evaluation criteria: Good product 〇 (ratio of bottom side wall thickness / top side wall thickness is 1 to 0.3), uneven thickness △ (bottom side wall thickness / top side wall thickness ratio is less than 0.3) ), Perforated ×.
The aperture ratio is expressed by the following mathematical formula (2).
Aperture ratio = container height (40 cm) ÷ container opening diameter (80 cm) Formula (2)

(9) Measurement of Average Length An ultrathin section having a thickness of 75 nm was prepared from the test piece (b), and a photograph at a magnification of 50,000 was taken using an electron microscope. Then, the photograph was taken into a scanner at a resolution of 200 dpi, and the minimum length and the maximum length of 100 cellulose-based polysaccharides (b) were determined using the particle analysis software of the image analyzer IP-1000 (manufactured by Asahi Kasei Co., Ltd.). each were measured and the respective arithmetic mean average length d ₁ of the minor _axis, the average length d ₂ of the long axis. Further, in the same manner as described above, the cellulose-based polysaccharide (b) alone is also photographed at a magnification of 50,000 times using an electron microscope, and the arithmetic mean of each is the average length d ₁ on the minor axis and the average length on the major axis. Measure d _2.

(10) Measurement of Hemicellulose Amount Quantitative analysis of hemicellulose in the cellulosic polysaccharide (b) is as follows.
The dispersion medium was removed from the dispersion liquid of the cellulosic polysaccharide (b) or the redispersion liquid of the cellulosic polysaccharide (b) obtained by dissolving and removing the resin component from the styrene resin composition, and the cellulose residue was recovered. The mass of the dried sample obtained by drying at 105 ° C. was measured by the following method.
The pulverized sample obtained by pulverizing the dried cellulose residue was extracted with an alcohol (ethanol) / benzene mixed solvent with a Soxhlet extractor for 6 hours. Then, extraction with alcohol (ethanol) / benzene mixed solvent) was further carried out for 4 hours to obtain a degreased sample. To 2.5 g of the defatted sample, 150 mL of distilled water, 1.0 g of sodium chlorite and 0.2 mL of acetic acid were added, and heat treatment was performed at 70 to 80 ° C. for 1 hour, and then 1.0 g of sodium chlorite and 0 acetic acid were again obtained. The operation of adding 2 mL and heating at 70 to 80 ° C. for 1 hour was repeated 3 to 4 times until the sample turned white. The obtained sample was filtered, washed with water and acetone, and dried at 105 ° C. to obtain a holocellulose fraction (total amount of α-cellulose and hemicellulose). The mass of this holocellulose fraction was measured.
Subsequently, 25 mL of a 17.5 mass% sodium hydroxide aqueous solution was added to 1.0 g of the holocellulose fraction, and after 3 minutes, the holocellulose fraction was lightly crushed with a glass rod until it became swollen. Then, let stand at 20 ° C., 30 minutes after adding the above sodium hydroxide aqueous solution, add 25 mL of distilled water, stir for exactly 1 minute, leave at 20 ° C. for 5 minutes, and filter with a glass filter. The solution was washed until it became neutral. Further, 40 mL of 10 mass% acetic acid was suction-filtered, and then 1 L of boiling water was suction-filtered and washed, and the sample was dried at 105 ° C. until the mass became constant to obtain an α-cellulose fraction. The mass of this α-cellulose fraction was measured.
From the mass of the holocellulose fraction and the α-cellulose fraction obtained as described above, the hemicellulose content was determined by the following formula.
Holocellulose (%) = holocellulose fraction (g) / sample (anhydrous base) (g) x 100 α-cellulose (%) = α-cellulose fraction (g) / sample (anhydrous base) (g) x 100 hemicellulose (%) = Holocellulose (%)-(α-cellulose (%))

The materials used in the examples and comparative examples are as follows.
[Styrene-based resin (a)]
[GPPS-1]
-Polystyrene with MFR 7.8 and a refractive index of 1.598 (GPPS, manufactured by PS Japan Corporation, HF77) was used.
[GPPS-2]
-Polystyrene with MFR 2.2 and a refractive index of 1.598 (GPPS, manufactured by PS Japan Corporation, G9401) was used.
[HIPS-1]
-Polystyrene with MFR3.0 and a refractive index of 1.558 (HIPS, manufactured by PS Japan Corporation, HT478) was used.
[HIPS-2]
-Polystyrene with MFR2.0 and a refractive index of 1.565 (HIPS, 475D manufactured by PS Japan Corporation) was used.
[Copolymerization-1]
Polymerization consisting of 70.0 parts by mass of styrene (ST), 15.0 parts by mass of butyl methacrylate (BA), 15.0 parts by mass of ethylbenzene, and 0.025 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. The raw material composition was applied to a fully mixed reactor with a capacity of 4 liters at a rate of 1.1 liters / hour, and then to a polymerization apparatus consisting of a laminar flow reactor with a capacity of 2 liters, and further unreacted monomers. , A styrene-based copolymer resin, Copolymer-1 was prepared by continuously and sequentially supplying it to a devolatilizer connected to a uniaxial extruder for removing volatile components such as a polymerization solvent.
The polymerization reaction conditions in the polymerization step were a polymerization temperature of 122 ° C. for the complete mixing reactor and a polymerization temperature of 120 to 142 ° C. for the laminar flow reactor. The devolatile unreacted gas was condensed in a condenser through which a refrigerant at −5 ° C. was passed, and recovered as an unreacted liquid.
The polymer content in the final polymerization solution was measured by the formula [(sample mass after drying / sample mass before drying) × 100%] after drying the polymerization solution at 215 ° C. under a reduced pressure of 2.5 kPa for 30 minutes. , 65.6% by mass, MFR was 4.6, and the refractive index was 1.578.
[Copolymerization-2]
It was produced in the same manner as in [Copolymerization-1] except that it was changed to 45.0 parts by mass of styrene (ST) and 40.0 parts by mass of methyl methacrylate (MA). The MFR was 3.2 and the refractive index was 1.542.
[Blend-1]
A mixture [HIPS-2 (95% by mass), SMA copolymer (5% by mass)] in which 5% by mass of an SMA copolymer (XIBOND250 manufactured by POLYSCOPE) is blended with the above HIPS-2 (475D). The MFR was 3.2 and the refractive index was 1.572.
[Blend-2]
A mixture of 5% by mass of a SMA copolymer (XIBOND250 manufactured by POLYSCOPE) in copolymer-1 [copolymer-1 (95% by mass), SMA copolymer (5% by mass)], and MFR. Was 5.0 and the refractive index was 1.584.
[Blend-3]
A mixture [GPPS-1 (90% by mass), copolymer-1 (10% by mass)] in which 10% by mass of the above copolymerization-1 is blended with the above GPPS-1 (HF77), and the MFR is 7.2. , The refractive index was 1.59.

[Cellulose-based polysaccharide (b)]
-Cellulose fiber-1 (manufactured by Celite, SW-10, d ₁ : 20 μm, d ₂ : 700 μm, hemicellulose content 11% by mass, lignin content 0.5% by mass, crystallinity 80%)
-Cellulose fiber-2 (manufactured by Celite, SW-30, d ₁ : 60 μm, d ₂ : 700 μm, hemicellulose content 15% by mass, lignin content 0.5% by mass, crystallinity 80%)
-CNF: Cellulose nanofiber (manufactured by Chuetsu Pulp Industry Co., Ltd., CNF-10, d ₁ : 35 nm, d ₂ : Approximately 1 μm, hemicellulose content 15% by mass, lignin content 0.2% by mass, crystallinity 75% )
-Cotton powder (manufactured by DTI Co., Ltd., 100% cotton crushed product, spherical body, d ₁ : 25 μm, d ₂ : 35 μm, hemicellulose content 0.5% by mass or less, lignin content 0.1% by mass, crystals Crystallinity 90%)
・ Hemicellulose (made by Wako Pure Chemical Industries, Ltd., xylan)
-Wood flour (manufactured by Naka Wood Co., Ltd., raw material: cedar, d ₁ : 40 μm, d ₂ : 300 μm, hemicellulose content 18% by mass, lignin content 18% by mass, crystallinity 55%)
(The content of the above lignin indicates the ratio to the total amount of each cellulosic polysaccharide (b).)

[Dispersant]
-Fatty acid ester: Glycerin monostearate (manufactured by Riken Vitamin Co., Ltd .: S-100)
-Terpen: Aromatically modified terpene resin (manufactured by Yasuhara Chemical Co., Ltd .: YS resin TO-105)

[Additive]
(Phenolic antioxidant)
Stearyl propionate (3,5-di-tert-butyl-4-hydroxyphenyl) (BASF, Irganox 1076)
(Phosphorus antioxidant)
Tris (2,4-di-tert-butylphenyl) phosphite (BASF, Inc., Irgafos 168)
(Liquid paraffin)
・ Liquid paraffin (CP-68N manufactured by Idemitsu Kosan Co., Ltd.)

[Examples 1 to 17]
Each component was added at the composition ratios shown in Table 1-1 and Table 1-2, and Irganox 1076 and Irgafos 168 were added as antioxidants to a total of 100 parts by mass of the components (a) and (b), respectively. After adding 2 parts by mass, the mixture was premixed. The obtained premix is mixed all at once and melt-extruded in the range of 180 ° C to 220 ° C using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., TEM-26SS) to pellet the styrene resin composition as a kneaded product. Got At this time, the screw rotation speed was 150 rpm and the discharge amount was 10 kg / hr. The pellets thus obtained were subjected to an injection molding machine manufactured by Japan Steel Works, Ltd. equipped with an ISO standard test piece type (a) mold, a cylinder temperature of 220 ° C., a mold temperature of 50 ° C., and an injection pressure (gauge). A test piece (a) was prepared by molding at a pressure of 40-60 MPa), an injection rate (panel set value) of 50%, and an injection time / cooling time = 5 sec / 20 sec. The heat shrinkage rate was evaluated using the obtained test piece (a).
Further, similarly, using an injection molding machine manufactured by Japan Steel Works, Ltd. equipped with a mold (b) having a thickness of 50 × 120 mm and a thickness of 1 mm, molding is performed under the same conditions as above to prepare a test piece (b). bottom. Then, using the obtained test piece (b), the total light transmittance was measured and the appearance of the molded product was evaluated. The evaluation results are shown in Table 1-1 and Table 1-2.
In addition, a non-foamed extruded sheet was prepared using the obtained pellet-shaped styrene resin composition. As for the non-foam extruded sheet, a 25 mmφ single-screw sheet extruder manufactured by Soken Co., Ltd. was used to prepare a sheet having a thickness of about 0.8 mm by setting the temperature of the resin melting zone to 180 to 200 ° C. Then, a container was prepared using the obtained sheet. As for the container, a sheet container molding machine manufactured by Soken Co., Ltd. was used, the heating zone was set to 200 ° C., and the container having a drawing ratio of 50% was vacuum formed to evaluate the spreadability. The results are shown in Table 1-1 and Table 1-2.

[Comparative Examples 1 to 5]
Comparative Examples 1 to 5 were carried out in the same manner as in Example 1 except that the composition was changed as shown in Table 2. Table 2 shows the results of measurement and evaluation of each physical property.

As shown in Table 1, Examples 1 to 17 have high total light transmittance, good light transmittance, and excellent surface appearance of the molded product. In addition, it has excellent heat resistance because it has a low heat shrinkage rate.
As shown in Comparative Examples 1 to 5 shown in Table 2, when the refractive index or MFR of the styrene resin deviates from a predetermined value, the light transmittance and the surface appearance of the molded product are inferior. Further, cellulose having an average diameter of the minor axis (d ₁ ) or the major axis (d ₂ ) (d ₁ ≤ d ₂ ) larger than 50 μm has low light transmission and is inferior in surface appearance and heat resistance of the molded product.

The molded product containing the styrene resin composition of the present invention can be suitably used for packaging materials, building materials, electronic / electrical parts, automobiles and the like.

Claims (5)

A styrene resin (a) having a refractive index of 1.545 to 1.600 and an MFR of 3 or more.
Have an average length _{d 2} of the average length _{d 1} and the _{d 1} or more in a long axis of the minor axis, cellulosic polysaccharides either _{d 1} or _{d 2} is 0.03~50μm (b) A styrene-based resin composition containing
The content of the styrene resin (a) is 45.0 to 99.5 parts by mass with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). , A styrene-based resin composition, characterized in that the content of the cellulosic polysaccharide (b) is 0.5 to 55.0 parts by mass. The styrene-based resin composition according to claim 1, wherein the styrene-based resin (a) contains an unsaturated carboxylic acid-based monomer unit. Claim 1 or 2 further contains 0.5 to 20 parts by mass of the dispersant (c) with respect to the total amount (100 parts by mass) of the styrene resin (a) and the cellulosic polysaccharide (b). The styrene-based resin composition according to. The dispersant (c) is one or more compounds selected from the group consisting of fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, and rosin compounds, according to claims 1 to 3. The styrene-based resin composition according to any one of the items. A molded product containing the styrene-based resin composition according to any one of claims 1 to 4.

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