JP2007211034A - Resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition excellent in dispersibility and transparency and suppressed in lowering of physical properties and excellent in shielding property of a specific wavelength. <P>SOLUTION: The resin composition is composed of (A) a thermoplastic resin and (C) zinc oxide having a coated layer of silicon oxide and having 0.01-0.1 μm average particle diameter and surface-treated so that the coated amount becomes 0.01-100 wt.% based on zinc oxide by (B) a hindered amine-based light stabilizer having ≥400 molecular weight. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition for thermoplastic resins. More specifically, the present invention relates to a resin composition excellent in shielding property, transparency and dispersibility at a specific wavelength and excellent in weather resistance.

The metal oxide has a function of shielding a specific wavelength. In addition, by controlling the particle size, it is expected to be used for applications that require transparency. For example, when the particle size is 0.1 μm or less, the scattering of visible light is suppressed and the film has a transparency function.

However, the metal oxide has a very strong cohesive strength. In particular, particles having a particle size of 0.1 μm or less easily aggregate because they have a large surface energy. Therefore, when they are kneaded into a resin or the like, the dispersion state is very poor, and the above functions cannot be fully exerted. . Furthermore, since the surface activity of the particles becomes very large, it has become a major factor for promoting resin degradation.

In order to solve the above problem, Patent Document 1 discloses a technique for suppressing surface activity by applying a coating layer of silicon oxide to fine zinc oxide having a particle size of 0.15 μm or less and surface-treating with organopolysiloxane. Is disclosed.

Patent Document 2 discloses a technique for improving weather resistance by using an organic ultraviolet absorber, an inorganic ultraviolet absorber, and a hindered amine light stabilizer in combination.

However, even if the resin composition technology disclosed in these publications is used, it has been difficult to obtain a resin composition or a molded product having high dispersibility, transparency and excellent physical properties.

Therefore, the use of organic compounds has become the mainstream for the above-mentioned uses having specific wavelength shielding and transparency. Among organic compounds, benzotriazole compounds can be mentioned as the most typical ones. The benzotriazole-based compound exhibits an immediate shielding effect due to its absorption action, but its use may be limited due to problems such as durability and safety.

Japanese Patent No. 3520785 JP 2003-325060 A

In order to solve the above-described problems, an object of the present invention is to provide a resin composition and a molded article that are excellent in dispersibility and transparency, and have excellent properties of shielding at a specific wavelength, while suppressing deterioration in physical properties.

The present invention is an oxidation having an average particle system of 0.01 to 0.1 μm, which has a thermoplastic resin (A) and a silicon oxide coating layer, and is surface-treated with a hindered amine light stabilizer (B). The present invention relates to a resin composition comprising zinc (C).

Furthermore, this invention relates to the said invention resin composition whose molecular weight of a hindered amine light stabilizer (B) is 400 or more.

Furthermore, this invention relates to the said resin composition whose coating amount of a hindered amine light stabilizer (B) is 0.01 to 100 weight% with respect to zinc oxide.

Furthermore, this invention relates to the said resin composition which zinc oxide (C) contains 0.01 to 30weight% with respect to a resin composition.

Furthermore, this invention relates to the said resin composition whose thermoplastic resin (A) is polyolefin.

Furthermore, this invention relates to the resin molded product characterized by using the said resin composition.

Since the resin composition of the present invention contains a thermoplastic resin (A) and zinc oxide (C) having a silicon oxide coating layer and surface-treated with a hindered amine light stabilizer (B), the thermoplastic resin ( Stable dispersion of zinc oxide is obtained without lowering the transparency of A), and the weather resistance is excellent, and the shielding property at a specific wavelength is excellent.

Since the molecular weight of the hindered amine light stabilizer (B) is 400 or more, the resin composition of the present invention is further excellent in zinc oxide dispersibility and weather resistance.

Moreover, since the coating amount of the hindered amine light stabilizer (B) is 0.01 to 100% by weight with respect to zinc oxide, the dispersibility and weather resistance are excellent.

Moreover, since zinc oxide (C) is 0.01 to 30 weight% with respect to the resin composition, it is further excellent in dispersibility.

Further, since the thermoplastic resin (A) is a polyolefin, a molded product that does not impair quality such as chromatic aberration and transparency can be obtained.

Since the molded article of the present invention is obtained using the above resin composition, it has properties such as dispersibility, specific wavelength shielding properties, weather resistance, and good appearance.

<Thermoplastic resin (A)>
Typical examples of the thermoplastic resin (A) used in the present invention include crystalline or amorphous polypropylene, polybutene-1, poly-4-methylpentene-1, low density polyethylene or high density polyethylene, EPCM resin, modified Polypropylene, modified polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene and propylene random, block or graft copolymer Examples thereof include a copolymer, a copolymer of α-olefin and ethylene or propylene, and further include polyethylene wax and polypropylene wax as pigment dispersion aids. Examples of the α olefin used for the copolymer with ethylene or propylene include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl 1-pentene, 1-decene, Examples include 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and the like.

The form of the thermoplastic resin (A) is not particularly defined, but a powder form is preferable in consideration of dispersibility such as zinc oxide (C).

<Hindered amine light stabilizer (B)>
The hindered amine light stabilizer (B) used in the present invention is a compound having a methylpiperidine skeleton, such as dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-succinate. Tetramethylpiperidine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6 -Tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], N, N′-bis (3-aminopropyl) ethylenediamine, 2,4 -Bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6, 6-tetra Methyl-4-piperidyl) sebacate and the like.

The average molecular weight of the hindered amine light stabilizer (B) used in the present invention is preferably 400 or more, and more preferably 400 to 5000. In particular, a thin molded article preferably has a high molecular weight having an average molecular weight of 2000 or more.

The concentration of the hindered amine light stabilizer (B) in the resin composition is 0.01 to 100% by weight, particularly preferably 0.01 to 25% by weight, based on zinc oxide serving as a substrate. When the concentration is less than 0.01% by weight, no improvement in the weather resistance of the molded product is observed as compared with the case where it is not added. When the concentration exceeds 100% by weight, bleeding of the hindered amine light stabilizer (B) becomes remarkable. This causes blocking of the composition and impairs handling properties. The concentration of the hindered amine light stabilizer (B) in the resin molded product is preferably 0.005 to 3% by weight, and may be contained in an amount necessary for the weather resistance required for the molded product. In particular, the content is preferably 0.005 to 2% by weight. When the concentration is less than 0.005% by weight, improvement in the weather resistance of the molded product is not observed as compared with the case where it is not added, and when it exceeds 3% by weight, the hindered amine light stabilizer (B) bleeds from the molded product. It becomes noticeable and the appearance of the molded product is greatly impaired.

<Zinc oxide (C)>
The primary particle size of zinc oxide (C) used in the present invention is 0.01 to 0.1 μm from the viewpoint of exerting the intended function in the present invention. 0.01-0.07 micrometer is preferable and 0.002-0.04 micrometer is more preferable.

Zinc oxide (C) has a coating layer made of silicon oxide on the surface of zinc oxide particles in an amount of 1 to 50% by weight, preferably 5 to 20% by weight, based on zinc oxide. The silicon oxide is not limited, but is preferably a hydrous silicon oxide. When the proportion of silicon oxide in the zinc oxide particle composition is less than 1% by weight, the surface activity of zinc oxide cannot be suppressed, and when it exceeds 50% by weight, the resulting zinc oxide particle composition is obtained. Is significantly reduced in dispersibility.

According to the present invention, an aqueous suspension of zinc oxide particles is added with 1 to 50% by weight of a water-soluble silicate as SiO2 with respect to zinc oxide, and the temperature is kept at 60 ° C. or higher for 40 minutes or more. The surface of the zinc oxide particles is made of silicon oxide by adding the acid as a neutralizing agent over a period of time and neutralizing the suspension until the pH is in the range of 6.0 to 8.0. A zinc oxide particle composition according to the present invention can be obtained by forming a coating layer. The concentration of the zinc oxide particles in the aqueous suspension is preferably in the range of 50 to 250 g / L, and the zinc oxide particles are desirably sufficiently pulverized from the zinc oxide raw material by a pulverizer such as a sand mill. . As the water-soluble silicate, sodium silicate or potassium silicate is preferably used, but is not limited thereto. The neutralizing agent is not limited, but inorganic acids such as sulfuric acid and organic acids such as acetic acid and oxalic acid are preferably used.

According to the present invention, after adding a water-soluble silicate to an aqueous suspension of zinc oxide particles, an acid is added thereto as a neutralizing agent to neutralize the water-soluble silicate, and The time condition (time width) for adding the neutralizing agent is important. That is, according to the present invention, a water-soluble silicate is added to an aqueous suspension of zinc oxide particles, and the temperature of the suspension is kept at 60 ° C. or higher, preferably 80 ° C. or higher for 40 minutes or longer. Preferably, the coating layer made of hydrous silicon oxide is obtained by adding a neutralizing agent over a period of 60 minutes or more and neutralizing the suspension to a pH of 6.0 to 8.0. Can be formed on the surface of zinc oxide.

As another method, an aqueous suspension of zinc oxide particles is maintained at a temperature of 60 ° C. or higher, preferably 80 ° C. or higher, and the water-soluble silicate and neutralizing agent are added for 40 minutes or longer. Can be added at the same time over a period of 60 minutes or more, and then neutralizing the suspension to a pH of 6.0 to 8.0 by adding a neutralizing agent. A coating layer made of silicon oxide can be formed on the surface of zinc oxide.

As a method for treating the hindered amine light stabilizer on the zinc oxide surface in the present invention, for example, the hindered amine light stabilizer is dissolved in a solvent, and the hindered amine system is stirred while stirring the zinc oxide with a stirrer (eg, Henschel mixer). By spraying and drying the light stabilizer solution, a hindered amine light stabilizer layer can be formed on the zinc oxide surface.

Further, the surface of zinc oxide can be subjected to organic treatment in order to further improve dispersibility as required. Although it does not specifically limit as an organic processing agent, Methyl hydrogen polysiloxane, carboxy modified polysiloxane, alcohol modified polysiloxane, epoxy modified polysiloxane, amino modified polysiloxane, methacryl modified poly Examples include siloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane. As silane coupling agents, methyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, phenyltrialkoxysilane And phenylalkoxysilanes such as diphenyldialkoxysilane, and dialkyldialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane.

The concentration of zinc oxide (C) in the resin composition is preferably 0.01 to 30% by weight, and particularly preferably 0.1 to 10% by weight. When the concentration is less than 0.1% by weight, the blocking property at a specific wavelength is not sufficient, and when it exceeds 30% by weight, aggregation of zinc oxide occurs and the value as a product is impaired.

<Resin composition>
In the coloring resin composition of the present invention, the thermoplastic resin (A) and zinc oxide (C) are mixed using a general high-speed shear mixer such as a Henschel mixer, a super mixer, etc. Manufactured by melt-kneading using a roll, three-roll, pressure kneader, Banbury mixer, single-screw kneading extruder, twin-screw kneading extruder, rotor-type twin-screw kneading extruder, etc., and then extruding into pellets Is done.

The resin composition of the present invention comprises a thermoplastic resin (A), a zinc oxide (C), a pellet-like compound that is used for molding without dilution, or a thermoplastic resin (A), and zinc oxide ( C) is contained in a high concentration, and refers to a pellet-like masterbatch that is used for molding by diluting the pigment content to a predetermined concentration with a resin to be colored (uncolored thermoplastic resin) during molding.

As the resin to be colored, the same resin as the thermoplastic resin used in the masterbatch production or a compatible resin can be used.

When the resin composition of the present invention is a master batch, the zinc oxide (C) content is preferably 3 to 30% by weight. If it exceeds 30% by weight, the dispersibility of zinc oxide (C) at the time of melt-kneading is poor, and the resin pressure rises in the extruder due to clogging of the wire mesh attached to the tip of the extruder at the time of master batch production and film forming May cause a significant decrease in productivity. Further, if it is less than 3% by weight, it tends to be economically disadvantageous.

When the resin composition of the present invention is a compound or a molded product, the content of zinc oxide (C) is preferably 0.01 to 30% by weight. If it exceeds 30% by weight, the dispersibility of zinc oxide (C) is poor, and as the wire mesh attached to the tip of the extruder during film forming is clogged, the resin pressure in the extruder is increased and the productivity is significantly reduced. Instead, the molded product has no commercial value.

<Molded product>
The molded product of the present invention may be formed by mixing a master batch pellet obtained by melt-extruding a resin dispersion having a relatively high zinc oxide concentration and a molding resin, and the zinc oxide concentration is compared. It may be formed by molding a low-priced compound as it is.

The molding method may be obtained by any method such as extrusion molding, injection molding and blow molding.

<Other ingredients>
Moreover, various additives can be used for the inorganic compound resin dispersion, the resin composition, and the molded product of the present invention within a range that does not impair the effects of the present invention, depending on each purpose.
The general dispersant is not particularly limited as long as it has good compatibility with the thermoplastic resin (A) and does not affect the thermoplastic resin (A).

For example, stearic acid, zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, ethylene bisamide, low molecular weight polyester, low molecular weight polyamide, low molecular weight polycarbonate, montanic acid ester, styrene-maleic anhydride copolymer resin, styrene -Acrylic acid copolymer resin, α-olefin / maleic anhydride copolymer resin, oxidized wax, glycerin wax, polystyrene wax, polyethylene wax, polypropylene wax and derivatives thereof, waxes made of acid-modified or hydroxyl-modified, etc. Can be mentioned. Any of these can be used alone or in combination. Here, the low molecular weight refers to a thing of 1000 Pa · s or less under 220 ° C. condition and 10 kg load with a capillary viscometer defined in JIS K 7199.

In addition, reinforcing agents (talc, mica, clay, wollastonite, calcium carbonate, glass fiber, glass beads, glass balloon, milled fiber, glass flake, carbon fiber, carbon flake, carbon bead, carbon milled fiber, metal flake, metal Fiber, metal coated glass fiber, metal coated carbon fiber, metal coated glass flake, silica, ceramic particle, ceramic fiber, aramid particle, aramid fiber, polyarylate fiber, graphite, conductive carbon black, various whiskers, etc.) Organic alkali metal salt And flame retardants other than organic alkaline earth metal salts (halogen, phosphate ester, metal salt, red phosphorus, metal hydrate, etc.), heat stabilizer, UV absorber, light stabilizer, mold release agent , Lubricants, sliding agents (PTFE particles, etc.), light diffusing agents (active Crosslinked particles, silicone crosslinked particles, ultrathin glass flakes, calcium carbonate particles, etc.), fluorescent brighteners, phosphorescent pigments, fluorescent dyes, antistatic agents, flow modifiers, crystal nucleating agents, inorganic and organic antibacterial agents, Examples thereof include impact modifiers typified by graft rubber, infrared absorbers, and photochromic agents.

The present invention will be described in more detail below, but the present invention is not limited to these examples without departing from the technical idea of the present invention. In the following, “parts by weight” is simply referred to as “parts”, and “% by weight” is simply referred to as “%”.

1. Production of zinc oxide (C) An aqueous suspension of zinc oxide (ZnO concentration 50 g / L) was heated to 80 ° C., and with stirring, an aqueous solution of 10% by weight sodium silicate as SiO 2 was added to the zinc oxide. added. After aging for 10 minutes, sulfuric acid was added with stirring over 60 minutes to neutralize to pH 6.5. After aging for 30 minutes, the resulting suspension was filtered, washed with water, and then dried by heating at 130 ° C. for 5 hours. The dried product thus obtained was subjected to jet mill pulverization to obtain zinc oxide particles (a) having a coating layer made of hydrous silicon oxide on the surface.
The hindered amine light stabilizer (CHIMASSORB 944FDL) having a molecular weight of 2000 to 3100, which is 50% of the weight of the base zinc oxide (a), is dissolved in acetone (50% by weight), and the zinc oxide (a) is stirred with a Henschel mixer. Acetone solution was sprayed and dried to obtain treated zinc oxide (I). The treated zinc oxide (I) was steam mill pulverized to produce zinc oxide (C).

2. Manufacture of resin composition Coated zinc oxide (C) 10%, Block-polypropylene (Prime Polypro J707 made by Prime Polymer Co., Ltd.) 94.9%, phenolic antioxidant 0.1% is blended in the super mixer. The dry mixture obtained by mixing was melt-kneaded and extruded at a temperature of 230 ° C. with a twin-screw kneading extruder to obtain a pellet-shaped resin composition (master batch).

3. The final concentration of zinc oxide (C) is 1% by using the resin compositions obtained in Examples and Comparative Examples of molded products and the thermoplastic resin used in the production of each resin composition. Then, an injection plate and an Izod test piece having a thickness of 1 mm were obtained by an injection molding machine.

4). Evaluation method (evaluation of dispersibility of zinc oxide)
Transmission electron microscope (TEM): An H-9000UHR transmission electron microscope (acceleration voltage 300 kV) manufactured by Hitachi, Ltd. was used to observe a 1 mm-thick injection plate. The results are shown in Table 2.
○: Maximum particle mass is less than 0.06 μm Δ: Maximum particle mass is 0.06 μm or more and less than 0.1 μm X: There is an aggregate of 0.1 μm or more

(Evaluation of specific wavelength shielding)
The average of the light transmittance at a wavelength of 350 nm in a 1 mm-thick injection plate was determined using UV-265FW manufactured by Shimadzu Corporation. An average means the arithmetic average value of the transmittance | permeability in arbitrary 10 places of a molded article. Here, the reason why the specific wavelength of 350 nm is measured is that it is possible to effectively shield the wavelength at which the photodecomposition of the resin becomes remarkable due to the basic absorption of zinc oxide (A). The results are shown in Table 2.
○: Transmittance at 350 nm is less than 10% Δ: Transmittance at 350 nm is 10% or more and less than 20% X: Transmittance at 350 nm is 20% or more

(Evaluation of weather resistance)
The physical property retention of Izod impact strength (ASTM C256) of the Izod test pieces of Examples and Comparative Examples after 2000 hours of the sunshine weather meter was determined. The retention rate is the retention rate of each impact strength value when the Izod impact strength value of the thermoplastic resin alone before the weather resistance test is 100%. Further, the appearance of the Izod test piece after 2000 hours was also evaluated. The results are shown in Table 2.

<Evaluation of Izod impact value>
○: Retention rate of 90% or more Δ: Retention rate of 80 to less than 90% ×: Retention rate of less than 80% <Appearance evaluation>
○: No choking △: Choking only on the surface ×: Deterioration is observed inside the molded product

(Evaluation of molded product appearance)
The surface of each 10-mm-thick injection plate was visually observed, and bleeding of the surface of the molded product due to volatile components was evaluated as follows. The results are shown in Table 2.
○: No bleed material was observed Δ: Bleed material was observed on one or more sheets ×: Bleed material was observed on all

A master batch was obtained in the same manner as in Example 1 using zinc oxide and a hindered and amine light stabilizer according to the formulation shown in Table 1, and a molded product was prepared and evaluated.
In addition, when the resin pressure of the resin composition in the Example of this invention was measured by the method of Japanese Patent Publication No. 1-38293, all were less than 10 kg / cm < ² >.

[Comparative Examples 1-6]
A master batch was obtained in the same manner as in Example 1 in accordance with the prescription in Table 1, and a molded product was prepared and evaluated. In Comparative Example 6, a master batch was obtained in the same manner as in Example 1 except that Kimasorb 944FDL was added to zinc oxide treated with silicon oxide, and a molded product was prepared and evaluated.

* Kimasorb 944FDL: molecular weight 2000-3100
* Kimasorb 119FL: Molecular weight 2286
* Tinuvin 770DF: molecular weight 481
* Tinuvin 234: Benzotriazole UV absorber

Claims (6)

Zinc oxide (C) having an average particle size of 0.01 to 0.1 μm, which has a thermoplastic resin (A) and a silicon oxide coating layer, and is surface-treated with a hindered amine light stabilizer (B). A resin composition comprising: The resin composition according to claim 1, wherein the hindered amine light stabilizer (B) has a molecular weight of 400 or more. The resin composition according to claim 1 or 2, wherein a coating amount of the hindered amine light stabilizer (B) is 0.01 to 100% by weight based on zinc oxide. The resin composition according to any one of claims 1 to 3, wherein the zinc oxide (C) is contained in an amount of 0.01 to 30% by weight based on the resin composition. The resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin (A) is a polyolefin. A resin molded product comprising the resin composition according to claim 1.