JP6738792B2 - Sunscreen resin composition - Google Patents

Description

The present invention relates to a sunscreen resin composition.

A device in which a predetermined device is built into a housing is installed side by side with various facilities installed outdoors. For example, in a base station of a mobile device such as a mobile phone or a smartphone, a communication device (module) housed in a casing (exterior body) or the like is provided to enable (wireless) communication of the mobile device outdoors or the like. It is provided.

The housing of such an apparatus installed outdoors (outdoor apparatus) is required to have resistance (durability and weather resistance) to rain, snow and sunlight. Further, in order to ensure stable operation of the built-in electronic device, a characteristic of suppressing an internal temperature rise due to sunshine (sunshine shielding property), and a characteristic of allowing communication radio waves to pass through are required for the base station and the like.
Examples of the material forming the housing of such an outdoor device include the above-mentioned metallic materials having excellent durability and weather resistance. However, some metallic materials are inferior in the sunlight shielding property, and some of them block communication radio waves. Therefore, a resin material has been attracting attention as a material for forming the housing, and its improvement is in progress. For example, a resin material containing titanium oxide or a housing (molded body) using this resin material has been proposed (Patent Documents 1 to 3).

JP, 7-258464, A JP, 2013-89866, A JP, 2014-28896, A

However, conventional resin materials or housings have not had sufficient sunlight shielding properties. Moreover, in recent years, the precision of electronic devices built into outdoor devices has also advanced, and in order to ensure stable operation, further improvement in the sunlight shielding property is required.
An object of the present invention is to provide a resin composition that exhibits excellent sunlight shielding properties.

The inventors of the present invention set the particle size of the titanium oxide particles used in combination with the thermoplastic resin to a specific distribution for the resin composition used for the material of the housing or the like, and the resin composition causes surface reflection (simply referred to as reflection). ) Found that it is possible to change the possible light profile. As a result of further study, in the resin composition containing the thermoplastic resin and the specific amount of titanium oxide particles, by setting the following frequency ratio for the titanium oxide particles in the range of 1.2 to 1.6, It was found that not only the near-infrared light having a wavelength of 780 to 2500 nm is totally reflected, but also the near-infrared light having a wavelength of 1750 to 2250 nm is highly reflected to exhibit a high sunshine shielding property. The present inventors have conducted further research based on this finding and have completed the present invention.

That is, the object of the present invention was achieved by the following means.
<1> A sunshine shielding resin composition containing 100 parts by mass of a thermoplastic resin and 10 to 80 parts by mass of titanium oxide particles,
Sunlight shielding property , wherein the titanium oxide particles include at least two kinds of small-diameter titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm and large-diameter titanium oxide particles having an average particle diameter of 0.40 to 0.45 μm . Resin composition.
<2> Of the titanium oxide particles measured by a laser analysis/scattering method with a class width of 50 nm using a sample solution obtained by dispersing the sunlight shielding resin composition in a solvent in which the thermoplastic resin is soluble. In the histogram of the particle size distribution, the ratio of the large frequency to the small frequency of the frequency of one lower class and the frequency of one higher class centering on the class indicating the mode value is 1.2 to 1.6, <1. > The sunscreen resin composition described in .
< 3 > The sunscreen resin composition according to < 2 >, wherein the mode value is 0.2 to 1.0 μm.
<4> The content of the previous SL small titanium oxide particles and the large particle size titanium dioxide particles, respectively, relative to the thermoplastic resin 100 parts by weight, from 5 to 30 parts by weight and 5 to 50 parts by mass <1> ~ The sunscreen resin composition according to any one of <3> .
< 5 > The sunscreen resin composition according to any one of <1> to < 4 >, wherein the thermoplastic resin is a polycarbonate or a fluororesin.
< 6 > The sunscreen resin composition according to any one of <1> to < 5 >, wherein the titanium oxide particles are surface-treated with at least one of alumina and zirconia.
< 7 > In any one of <1> to < 6 >, containing 0.01 to 5 parts by mass of at least one selected from an ultraviolet absorber and a light stabilizer with respect to 100 parts by mass of the thermoplastic resin. The sunscreen resin composition described.
< 8 > Containing 5 to 30 parts by mass of at least one flame retardant selected from a brominated flame retardant, a metal hydrate, a phosphate compound and ammonium polyphosphate based on 100 parts by mass of the thermoplastic resin <1> to < 7 > The sunscreen resin composition according to any one of <1> to < 7 >.
< 9 > A mixture of a thermoplastic resin, small-sized titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm, and large-sized titanium oxide particles having an average particle diameter of 0.40 to 0.45 μm <1> to < 8 > The sunscreen resin composition according to any one of < 8 >.

In the present specification, the numerical range represented by using "to" means a range including the numerical values before and after "to" as the lower limit value and the upper limit value.

The present invention can provide a resin composition exhibiting excellent sunlight shielding properties.

[Sunscreen resin composition]
The sunlight shielding resin composition of the present invention contains 100 parts by mass of a thermoplastic resin and 10 to 80 parts by mass of titanium oxide particles, and satisfies the following frequency ratio in the histogram of particle size distribution. That is, the particle size of titanium oxide particles measured by a laser analysis/scattering method with a class width of 50 nm using a sample solution obtained by dispersing the sunlight shielding resin composition of the present invention in a solvent in which a thermoplastic resin is soluble. In the distribution histogram, the ratio of the large frequency to the small frequency (frequency ratio) between the frequency of one lower class and the frequency of one higher class is 1.2 to 1 centering on the class indicating the mode value. .6.
Details of the frequency ratio of the titanium oxide particles contained in the sunlight shielding resin composition of the present invention will be described later.
This frequency ratio is, for example, as described later, for small-diameter titanium oxide particles having an average particle diameter (mode diameter) of 0.15 to 0.25 μm and large-diameter titanium oxide particles having an average particle diameter of 0.35 to 0.45 μm. The above range can be set by including at least two kinds of
The sunscreen resin composition of the present invention containing the titanium oxide particles satisfying the above frequency ratio exhibits excellent sunscreen properties. That is, in the solar shading resin composition of the present invention, when the above frequency ratio is satisfied, the reflectance for near infrared light having a wavelength of 780 to 2500 nm is improved overall, and the heat ray into the solar shading resin composition is increased. Can be prevented. Further, it is possible to increase the reflectance with respect to near-infrared light having a wavelength of 1750 to 2250 nm, which has conventionally been insufficient in reflectance. As described above, the sunlight shielding resin composition of the present invention can simultaneously increase the overall reflectance of near infrared light and the reflectance for near infrared light having a wavelength of 1750 to 2250 nm to a high level. Thereby, the effect of suppressing the temperature rise inside the housing made of the sunlight shielding resin composition of the present invention can be enhanced.
In particular, the sunscreen resin composition of the present invention comprises a thermoplastic resin, small-diameter titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm, and large-diameter titanium oxide having an average particle diameter of 0.35 to 0.45 μm. When composed of a mixture with particles, the titanium oxide particles synergistically exhibit the function and function to achieve the overall reflectance of near infrared light and the reflectance for near infrared light of wavelength 1750 to 2250 nm. At the same time, it can be raised to a high standard. That is, in the sunlight-shielding resin composition of the present invention, the small-diameter titanium oxide particles improve the reflectance with respect to near-infrared light having a wavelength of 780 to 2500 nm, and the large-diameter titanium oxide particles with respect to near-infrared light having a wavelength of 1750 to 2250 nm. The reflectance can be improved.

<Thermoplastic resin>
The thermoplastic resin used in the present invention is not particularly limited, and examples thereof include polyolefin resin, engineering plastic, and fluororesin. Further, the thermoplastic resin described in paragraph [0011] of Patent Document 1 is mentioned, and this description is preferably incorporated herein. Among them, as the thermoplastic resin, polyolefin resin (polyethylene or polypropylene), (super) engineering plastic (polycarbonate, polyphenylene sulfide or nylon resin) or fluororesin (ETFE (resin consisting of a copolymer of tetrafluoroethylene and ethylene)) , PTFE (polytetrafluoroethylene) or PVA (polyvinyl fluoride: PVF)) are preferred.
Particularly, from the viewpoint of practical use, polycarbonate having a high impact property is preferable, from the viewpoint of sunlight shielding property, the fluororesin is preferable, and from the viewpoint of easy availability and price, polyethylene or polypropylene is preferable.
The thermoplastic resin contained in the sunlight shielding resin composition of the present invention may be one kind or two or more kinds.

<Titanium oxide particles>
The titanium oxide particles used in the present invention are not particularly limited as long as they are particles of titanium oxide and satisfy the above frequency ratio. The crystal form of titanium oxide forming the titanium oxide particles is not particularly limited, and may be anatase type, rutile type, or a mixture thereof. Of these, the rutile type is preferable.

The titanium oxide particles contained in the sunscreen resin composition of the present invention may be one type of titanium oxide particles having a certain particle size distribution (peak particle size), as long as they satisfy the frequency ratio described below as a whole. Alternatively, it may be composed of two or more kinds of titanium oxide particles having different particle size distributions (peak particle diameters). For example, a mixture (mixture) composed of two kinds of titanium oxide particles having at least one peak particle diameter in the range of 0.15 to 0.25 μm and at least one in the range of 0.35 to 0.45 μm in the particle size distribution can be mentioned. .. In the present invention, the titanium oxide particles have at least one kind of titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm (sometimes referred to as small-sized titanium oxide particles) and an average particle diameter of 0.35 to 0.35. Those containing at least one kind of titanium oxide particles of 0.45 μm (sometimes referred to as large-diameter titanium oxide particles) are preferable.
The sunscreen resin composition of the present invention contains titanium oxide particles (in the case where two or more kinds of titanium oxide particles are contained, all titanium oxide particles, for example, small-diameter titanium oxide particles and large-diameter titanium oxide particles are included unless otherwise specified). By using the above meaning, the frequency ratio can be set within the above range, and as described above, the reflection of near-infrared light as a whole and the near-infrared light in a specific wavelength region are at a high level. It is well-balanced and can be reflected.

− How to obtain frequency ratio and average particle size −
In the present invention, the frequency ratio of titanium oxide particles and the average particle diameter (peak particle diameter) can be determined as follows.
When titanium oxide particles are used in the preparation of the sunscreen resin composition of the present invention, the titanium oxide particles are used as a measurement target.
On the other hand, regarding the titanium oxide particles contained in the sunlight-shielding resin composition of the present invention, the titanium oxide particles taken out from the resin composition are to be measured. As a method for taking out the titanium oxide particles from the resin composition, for example, the thermoplastic resin contained in the sunscreen resin composition of the present invention is soluble in a solvent, the sunscreen resin composition of the present invention is added. A method of obtaining a dispersion liquid of titanium oxide particles by dissolving a thermoplastic resin can be mentioned. Specifically, 0.1 to 0.2 g (5 mm x 5 mm) of a sample (sunshielding resin composition) is put in an arbitrary sample tube, and a solvent (when the thermoplastic resin is polycarbonate (PC), it is put therein). Add 30 mL of tetrahydrofuran (THF) and a stir bar. A magnetic stirrer is stirred for about one day until the thermoplastic resin is completely dissolved in the solvent to obtain a dispersion liquid. The dispersion liquid thus obtained is irradiated with ultrasonic waves for 30 minutes using an ultrasonic bath cleaner (2510-MT, output 100 W, 42 KHz, manufactured by BRANSON) to obtain a dispersion liquid of titanium oxide particles.
When the resin composition contains particles other than the titanium oxide particles, the titanium oxide particles are separated by a usual method based on the specific gravity of each particle after the particles are taken out as described above.

The frequency ratio is determined by the laser analysis/scattering method using the titanium oxide particles used for the preparation of the sunscreen resin composition or the dispersion liquid obtained as described above as a sample liquid, and the particle size to be 50 nm, and the particle size. Create a histogram of the distribution. The measurement conditions of the laser analysis/scattering method are as follows.
In the obtained histogram, the class indicating the mode value with the maximum frequency is determined, and the frequency of one lower class (F ^CL1 ) and the frequency of one higher class (F ^CH1 ) are read around this class. That is, the frequencies of two classes adjacent to the class indicating the mode value are read. The ratio (F ^CL1 /F ^CH1 or F ^CH1 /F ^CL1 ) of the large frequency to the small frequency of the two frequencies thus read is calculated. The ratio of the frequency of titanium oxide particles is the average value of the two measurement results.
<Measurement conditions>
・Measuring device: Laser analysis/scattering particle size distribution measuring device LA-950V2 (manufactured by Horiba Ltd.)
・Measuring unit: Wet
・Measurement mode: Manual batch cell measurement ・Measurement range: 0.01 to 3000 μm
・Particle size standard: Volume standard ・Dispersion medium: THF
-Refractive index 2.72 (sample refractive index)/1.404 (dispersion medium refractive index)
・Number of measurements: 2 times

In the present invention, the frequency ratio of titanium oxide particles is preferably 1.3 to 1.5.
In the present invention, the mode value is preferably in the range of 0.2 to 1.0 μm, and more preferably in the range of 0.2 to 0.8 μm in terms of the above-mentioned shielding property.
The peak particle diameter is the particle diameter (mode diameter) having the highest frequency in a predetermined particle diameter range in the histogram obtained by the above measurement.

The titanium oxide particles may be surface-untreated or surface-treated, and surface-treated particles are preferable. As the surface treatment agent for the titanium oxide particles, those usually used can be used without particular limitation. For example, an inorganic oxide, an inorganic hydroxide, an organic compound, etc. are mentioned.
The inorganic oxide is preferably a metal oxide, and examples thereof include alumina (aluminum oxide), zirconia (zirconium dioxide), silica (silicon dioxide), siloxane (silicon dioxide compound), zinc oxide, or a mixture thereof. .. The inorganic hydroxide is preferably a metal hydroxide, and examples thereof include aluminum hydroxide, magnesium hydroxide, calcium hydroxide and the like.
Examples of the organic compound include a silane coupling agent, a polyol surface treatment agent, an amine surface treatment agent, and a silicone surface treatment agent. The polyol-based surface treatment agent, the amine-based surface treatment agent and the silicone-based surface treatment agent are not particularly limited, and examples thereof include the surface treatment agent described in paragraph [0042] of Patent Document 3, and this description is preferable. Are incorporated herein. The silane coupling agent is not particularly limited, and known ones can be used.

In the present invention, the titanium oxide particles are preferably surface-treated, more preferably an inorganic oxide (particularly siloxane, alumina or zirconia) or an inorganic hydroxide, and at least alumina and zirconia. More preferably, the surface treatment is performed with one kind.
When the small-diameter titanium oxide particles and the large-diameter titanium oxide particles are used in combination as the titanium oxide particles, both the small-diameter titanium oxide particles and the large-diameter titanium oxide particles are preferably surface-treated, and an inorganic oxide or an inorganic water is used. More preferably, it is surface-treated with an oxide. The surface treatment agent at this time is not particularly limited, but for example, it is more preferable that the surface treatment agent for the small diameter titanium oxide particles is an inorganic hydroxide and the surface treatment agent for the large diameter titanium oxide particles is an inorganic oxide. ..
The surface treatment amount of the titanium oxide particles is not particularly limited, but can be, for example, 0.05 to 5 parts by mass with respect to 100 parts by mass of the titanium oxide particles.

The titanium oxide particles may be appropriately produced, or a commercially available product may be used. The method for synthesizing titanium oxide is not particularly limited, and examples thereof include a sulfuric acid method, a chlorine method, and various other methods.

The titanium oxide particles contained in the sunscreen resin composition of the present invention may be one kind or two or more kinds.

<UV inhibitor>
The sunscreen resin composition of the present invention preferably contains at least one of an ultraviolet absorber and a light stabilizer.
The ultraviolet absorber and the light stabilizer are not particularly limited, and examples thereof include those usually used. Examples of ultraviolet absorbers include benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, benzophenone ultraviolet absorbers, triazine ultraviolet absorbers, cyclic iminoester ultraviolet absorbers, and cyanoacrylates. Further, examples of the light stabilizer include a hindered amine light stabilizer. As the ultraviolet absorber and the light stabilizer, a benzophenone ultraviolet absorber or a hindered amine light stabilizer is preferable, and a hindered amine light stabilizer is more preferable.
Examples of benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, benzophenone ultraviolet absorbers, cyclic iminoester ultraviolet absorbers and cyanoacrylates include, for example, the ultraviolet absorbers described in paragraphs [0045] to [0049] of Patent Document 3. Agents are included, and these descriptions are preferably incorporated herein. Further, as the benzotriazole ultraviolet absorber, in addition to those described in the above patent documents, 2(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-2(ethylhexahexa Noyloxy)ethoxy]phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol (as a commercial product, for example, ADEKA STAB LA-36 (trade name, manufactured by ADEKA) , Etc.) and the like. The triazine UV absorber is not particularly limited as long as it is other than the benzotriazole UV absorber, and examples thereof include 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1, 3,5-triazine and the like can be mentioned.
As the hindered amine light stabilizer, Terakis (1,2,2,6,6-pentemethyl-4-piperidyl)butane-1,2,3,4-tetracarboxyate (commercially available, ADEKA STAB LA-52 (trade name, Manufactured by DEKA.), Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (commercially available, ADEKA STAB LA-57 (trade name, ADEKA Manufactured) are mentioned.) etc. are mentioned.
In the present invention, when the ultraviolet absorber has a hindered amine skeleton in the molecule, it is classified as a hindered amine light stabilizer even if it has a phenol skeleton or a benzimidazole skeleton, regardless of other skeletons (groups). To do.
In the present invention, hindered amine light stabilizers are preferred.
The ultraviolet absorber contained in the sunscreen resin composition of the present invention may be one kind or two or more kinds.

<Flame retardant>
The sunlight shielding resin composition of the present invention preferably contains a flame retardant.
The flame retardant is not particularly limited, and examples thereof include those normally used. Examples thereof include brominated flame retardants, metal hydrates, phosphate compounds, ammonium polyphosphate, and fluorine-containing organic salts.
The bromine-based flame retardant is not particularly limited, and examples thereof include a bromine-based flame retardant among “halogen-based flame retardants” described in Patent Document 3, paragraphs [0053] and [0054]. Preferably incorporated herein. Other than this, for example, decabromodiphenylethane and the like can be mentioned.
The metal hydrate is not particularly limited, and examples thereof include hydrates or hydroxides of metal elements. For example, magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like can be mentioned. The metal hydrate may be surface-treated with a fatty acid such as stearic acid or a silane coupling agent.
The phosphate compound is not particularly limited, and examples thereof include the compounds described in paragraphs [0039] to [0053] of JP 2008-63458 A, which descriptions are preferably incorporated herein. Be done. Specific examples include melamine pyrophosphate and piperazine pyrophosphate.
The fluorine-containing organic salt is not particularly limited, and examples thereof include those described in paragraph [0060] of Patent Document 3, and these descriptions are preferably incorporated herein.

In the present invention, the flame retardant is preferably at least one selected from brominated flame retardants, metal hydrates, phosphate compounds and ammonium polyphosphate, more preferably a phosphate compound and melamine pyrophosphate. Further preferred is the combination of piperazine pyrophosphate.
The flame retardant contained in the sunlight shielding resin composition of the present invention may be one type or two or more types.

<Additive>
The sunscreen resin composition of the present invention can also contain additives other than the ultraviolet absorber and the flame retardant. These additives are not particularly limited as long as they are commonly used in resin compositions. Examples of such additives include antioxidants, inorganic fillers, other resins or elastomers, colorants, sliding agents, light diffusing agents, fluorescent dyes, inorganic phosphors, fluorescent whitening agents, and charge absorption. Agents, inorganic or organic antibacterial agents, photocatalytic antifouling agents, radical generators, infrared absorbers (heat ray absorbers), photochromic agents and the like.
The antioxidant is not particularly limited, and examples thereof include a hindered phenol antioxidant and a phosphorylation inhibitor. The antioxidant is not particularly limited, but examples thereof include those described in paragraph [0077] to paragraph [0083] of Patent Document 3, and these descriptions are preferably incorporated herein. Other than this, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (commercially available product is Irganox 1010 (trade name, manufactured by BASF)). The above-mentioned additive is not particularly limited, and examples thereof include those described in paragraph [0085] to paragraph [0088] of Patent Document 3, and these descriptions are preferably incorporated herein.
Among the above additives, the sunscreen resin composition of the present invention preferably contains an antioxidant.

<Content of each component>
In the sunlight shielding resin composition of the present invention, the (total) content of the titanium oxide particles is 10 to 80 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the content of the titanium oxide particles is less than 10 parts by mass, the sunlight shielding property is poor. On the other hand, when it exceeds 80 parts by mass, there arises a problem that mechanical properties such as impact properties are deteriorated. The content of titanium oxide particles is preferably 15 to 50 parts by mass, and more preferably 20 to 30 parts by mass, with respect to 100 parts by mass of the thermoplastic resin, in view of having a good balance between the sunlight shielding property and the mechanical properties.
When the sunlight-shielding resin composition of the present invention contains small-diameter titanium oxide particles and large-diameter titanium oxide particles as titanium oxide particles, the content of the small-diameter titanium oxide particles is the (total) content of the titanium oxide particles as described above. The amount is not particularly limited as long as it satisfies the range, but is preferably 5 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the content of the small-diameter titanium oxide particles is within this range, the reflectance of near-infrared light in sunlight can be increased as a whole without impairing the effect of the large-sized titanium oxide particles. The content of the small-diameter titanium oxide particles is more preferably 5 to 25 parts by mass, still more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin. On the other hand, the content of the large-diameter titanium oxide particles is not particularly limited as long as the (total) content of the titanium oxide particles satisfies the above range, but is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the content of the large-diameter titanium oxide particles is within this range, the reflectance for near-infrared light having a wavelength of 1750 to 2250 nm in sunlight can be increased without impairing the above-described effects of the small-sized titanium oxide particles. .. The content of the large-diameter titanium oxide particles is more preferably 5 to 30 parts by mass, further preferably 5 to 25 parts by mass, and particularly preferably 10 to 20 parts by mass, relative to 100 parts by mass of the thermoplastic resin. The ratio of the content of large titanium oxide particles to the small titanium oxide particles [content of large titanium oxide particles/content of small titanium oxide particles] is not particularly limited, but 0.5 to 5 is more preferable. , 0.9 to 1.1 are more preferable.

In the sunlight shielding resin composition of the present invention, the content of the ultraviolet ray inhibitor and the light stabilizer is not particularly limited and can be appropriately set, but in total with respect to 100 parts by mass of the thermoplastic resin, The amount is preferably 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass. When the above-mentioned content of the ultraviolet protective agent and the light stabilizer is 0.01 to 5 parts by mass, weather resistance can be imparted without impairing the excellent sunlight shielding property.

In the sunlight-shielding resin composition of the present invention, the content of the flame retardant is not particularly limited and may be appropriately set, but it is 5 to 30 parts by mass in total with respect to 100 parts by mass of the thermoplastic resin. Is preferable and 20-30 mass parts is more preferable. When the content of the flame retardant is 5 to 30 parts by mass, the flame retardancy can be imparted without impairing the excellent sunlight shielding property.

In the sunlight shielding resin composition of the present invention, the total content of the above additives is not particularly limited, but is preferably 0 to 150 parts by mass, and 0 to 65 parts by mass with respect to 100 parts by mass of the thermoplastic resin. More preferably, it is a part.

<Characteristics or physical properties>
The sunlight shielding resin composition of the present invention preferably has the following properties or physical properties.
The sunlight-shielding resin composition of the present invention can be exerted even if it is molded into a housing described later without impairing the following characteristics or physical properties.
− Reflectivity for near infrared light −
The solar radiation shielding resin composition of the present invention preferably has a solar reflectance (referred to as near infrared reflectance) for near infrared light having a wavelength of 780 to 2500 nm (referred to as near infrared reflectance) of 75% or more, and 80% or more. More preferable. The upper limit is practically 84%. The method for measuring the near infrared reflectance will be described later.

-Maximum reflectance for light having a wavelength of 1750 to 2250 nm-
The sunlight-shielding resin composition of the present invention has a maximum reflectance of near infrared light having a wavelength of 1750 to 2250 nm of preferably 60% or more, more preferably 70% or more, and more preferably 80% or more. More preferably. The upper limit is practically 81%.
The maximum reflectance for near-infrared light having a wavelength of 1750 to 2250 nm refers to the largest reflectance (peak value) in the region of wavelengths 1750 to 2250 nm in the spectrum obtained by the above measuring method.

The sunscreen resin composition of the present invention exhibits flame retardancy or weather resistance.
In particular, when it contains a flame retardant or an ultraviolet protective agent, it exhibits excellent flame retardancy or weather resistance and is preferable as a housing for outdoor installation equipment.

<Method for preparing the sunscreen resin composition of the present invention>
The sunscreen resin composition of the present invention can be prepared by mixing the above components, for example, a thermoplastic resin with small-sized titanium oxide particles and large-sized titanium oxide particles by a conventional method. The mixing method is not particularly limited as long as the above components can be mixed, and a usual mixing method used for preparing a rubber composition can be adopted. As the mixing device, for example, a single-screw extruder (single-screw kneader), a twin-screw extruder (twin-screw kneader), a roll, a Banbury mixer, or various kneaders are used.
The mixing conditions are not particularly limited. For example, the mixing temperature may be a temperature at which the above components can be mixed, and for example, room temperature (25°C) to 350°C is preferable, and 150 to 300°C is more preferable. The mixing time may be set to a time at which the above components can be mixed, and can be appropriately set according to the mixing temperature or the mixing state. The order of mixing the respective components is not particularly limited, and they may be mixed simultaneously (at once) or sequentially. The mixing amount of each component is preferably in the same range as the content of each component in the sunscreen resin composition of the present invention.

<Use>
The sunscreen resin composition of the present invention is preferably used as a material for forming a casing of an outdoor device. The outdoor device in which the housing formed of the sunscreen resin composition of the present invention is preferably used is not particularly limited, but an outdoor device incorporating an electronic device is preferable. For example, mobile equipment base stations (communication devices), public wireless LANs, solar cell modules, power conditioners, electricity meters, outdoor devices (smart meters, smart grid concentrators, etc.) used for next-generation power transmission networks (smart grids). , An electric vehicle charging device, a surveillance camera, an air conditioner outdoor unit, and the like. Among the outdoor devices, outdoor devices that transmit and receive radio waves are preferable, and base stations (communication devices) of mobile devices are preferable.

The method for forming a housing of an outdoor device using the sunscreen resin composition of the present invention is not particularly limited, and examples thereof include a method of molding the sunscreen resin composition of the present invention. The molding method is not particularly limited as long as it is a method capable of molding the sunlight shielding resin composition of the present invention, and a known molding method can be adopted.

The housing made of the sunscreen resin composition of the present invention exhibits the above-mentioned excellent properties or physical properties exhibited by the sunscreen resin composition of the present invention.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
In Tables 1 and 2, unless otherwise specified, the numerical values relating to the compounding amount of each example represent parts by mass. In addition, a blank for each component means that the blending amount of the corresponding component is 0 part by mass.

Details of each component (compound) shown in Table 1 and Table 2 are shown below.
<Thermoplastic resin>
Polycarbonate: Panlite L1225 (trade name, manufactured by Teijin Ltd.)
Polyethylene: DFDJ7540 (trade name, manufactured by NUC)
Polypropylene: PM600A (trade name, manufactured by Sun Allomer)
ETFE (resin consisting of copolymer of tetrafluoroethylene and ethylene): Fluon (registered trademark) LM-720AR (trade name, manufactured by Asahi Glass Co., Ltd.)
<Titanium oxide particles>
Small diameter titanium oxide particles: CR-60 (trade name, average particle diameter 0.21 μm, crystal form: rutile type, surface treatment agent: aluminum hydroxide, manufactured by Ishihara Sangyo Co., Ltd.)
Large-diameter titanium oxide particles: R-38L (trade name, average particle size 0.40 μm, crystal form: rutile type, surface treatment agent: alumina-zirconia, manufactured by Sakai Chemical Industry Co., Ltd.)
The average particle diameter of the titanium oxide particles is a value measured by the above method.
<Flame retardant>
Brominated flame retardant: Firemaster 2100R (trade name, decabromodiphenylethane, manufactured by Chemtura)
Magnesium hydroxide: Kisuma 5A (trade name, fatty acid surface treatment, manufactured by Kyowa Chemical Industry Co., Ltd.)
Phosphate compound: ADEKA STAB FP2100J (trade name, manufactured by ADEKA)
<Light stabilizer>
Hindered amine light stabilizer: ADEKA STAB LA-52 (trade name, manufactured by ADEKA)

(Examples 1 to 9 and Comparative Examples 1 to 10)
Each component was kneaded with a biaxial kneader in a mixing amount shown in Table 1 and Table 2 to obtain a resin composition. This was pelletized to prepare the sunscreen resin compositions of Examples 1 to 9 and the resin compositions of Comparative Examples 1 to 10, respectively. The mixing conditions were set to a mixing temperature of 240° C., a mixing time of 5 to 10 minutes, and a rotation speed of 165 to 200 rpm.
Each of the obtained resin compositions was injection-molded to produce a sheet having a thickness of 2 mm. The injection molding conditions were set to a molding temperature of 240 to 250° C. and an injection pressure of 120 to 150 MPa.

Using each manufactured sheet, the frequency ratio, mode value, reflectance and heat shield performance were evaluated. The results are shown in Tables 1 and 2.
<Frequency ratio>
0.1 to 0.2 g (5 mm×5 mm×2 mm) of each sheet was put into 30 mL of tetrahydrofuran and stirred to dissolve the thermoplastic resin. The obtained solution was irradiated with ultrasonic waves for 30 minutes using an ultrasonic bath cleaner: 2510-MT (trade name, output 100 W, 42 KHz, manufactured by BRANSON) to prepare a dispersion liquid of titanium oxide particles. For this dispersion, the particle size distribution of titanium oxide particles was measured by a laser analysis/scattering method under the following measurement conditions using a laser analysis/scattering particle size distribution measuring device: LA-950V2 (trade name, manufactured by Horiba Ltd.). Then, a histogram (ordinary histogram) was created with the class width of 50 nm.
In the thus obtained histogram for titanium oxide particles, a class indicating a mode value (referred to as a mode class) is determined, and two classes adjacent to this mode class, that is, one higher class and one lower class, Read the frequency of. Of the two read frequencies, the large frequency was divided by the small frequency to obtain the frequency ratio. The frequency ratio of titanium oxide particles was the average value of the two measurement results. The results are shown in Table 1.
It was confirmed that the mode values of Examples and Comparative Examples were all within the range of 0.2 to 1.0 μm.
(Measurement condition)
・Measuring unit: Wet
・Measurement mode: Manual batch cell measurement ・Measurement range: 0.01 to 3000 μm
・Particle size standard: Volume standard ・Refractive index 2.72 (Sample refractive index)/1.404 (Dispersion medium refractive index)
・Number of measurements: 2 times

<Reflectance>
For each sheet, a double monochromator type spectrophotometer: SolidSpec-3700DUV (manufactured by Shimadzu Corporation) was used, in accordance with JIS K5602, a measurement resolution of 1 μm, aluminum oxide was used as a reference, and a measurement range was set to 250 to 2500 nm. Then, the solar reflectance was measured.
Using the obtained solar reflectance spectrum, the solar reflectance (near infrared reflectance) for near-infrared light (wavelength 780 to 2500 nm) is calculated according to the formula stipulated in JIS K 5602 “8 Method of obtaining solar reflectance”. I asked. In this test, near infrared reflectance of 75% or more is a pass level.
In addition, using the obtained solar reflectance spectrum, the maximum reflectance (in the 1750 to 2250 nm region) in the near infrared light with a wavelength of 1750 to 2250 nm is calculated according to the formula stipulated in JIS K 5602, “How to obtain 8 solar reflectance”. The maximum reflectance) was calculated. In this test, 60% or more of the maximum reflectance in the 1750 to 2250 nm region is a pass level.

<Heat shielding performance>
The heat shield performance of each sheet was evaluated using a light source 250 W infrared lamp (illuminance 1250±50 lux voltage 40 V) specified by ASTM D4803-97. Specifically, the temperature of the back surface of the sheet was measured after irradiating the surface of the sheet with infrared rays emitted from the infrared lamp from a height of 200 mm for 2 hours. As a control, the temperature of the back surface of the general coated plate was measured in the same manner for the general coated plate (electrogalvanized steel plate, length: 120 mm, width: 80 mm, thickness: 1.6 mm, manufactured by Nippon Steel & Sumikin Co., Ltd.).
The difference between the temperature of the back surface of the general coating plate and the temperature of the back surface of the sheet measured in this way ((temperature of the back surface of the general coating plate)-(temperature of the back surface of the sheet)) is calculated, and this temperature difference is used. The heat shield performance was evaluated.
In this test, the larger the temperature difference is, the higher the heat shielding performance is, and the pass level is 7°C or higher.

From the results of Table 1 and Table 2, the following can be seen.
Comparative Examples 1 to 10 in which the content of the titanium oxide particles with respect to the thermoplastic resin and the frequency ratio deviate from the range defined in claim 1 are all those with low reflectance and sufficient heat shield performance. Absent.
On the other hand, in Examples 1 to 9 in which the content of the titanium oxide particles with respect to the thermoplastic resin and the frequency ratio satisfy the range defined in claim 1, near-infrared reflectance and 1750 to 2250 nm are all satisfied. It has a high maximum reflectance for light and exhibits excellent heat shield performance. Thus, the sunlight shielding resin composition of the present invention can achieve both high reflectance and high shielding performance. In particular, when a fluorocarbon resin is used as the thermoplastic resin, the reflectance can be improved to a higher level.

Claims (9)

A solar shading resin composition containing 100 parts by mass of a thermoplastic resin and 10 to 80 parts by mass of titanium oxide particles,
Sunlight shielding property , wherein the titanium oxide particles include at least two kinds of small-diameter titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm and large-diameter titanium oxide particles having an average particle diameter of 0.40 to 0.45 μm . Resin composition. Of the particle size distribution of the titanium oxide particles measured by a laser analysis/scattering method with a class width of 50 nm using a sample solution obtained by dispersing the sunlight shielding resin composition in a solvent in which the thermoplastic resin is soluble. In the histogram, the ratio of the large frequency to the small frequency of the frequency of one lower class and the frequency of one higher class centering on the class indicating the mode value is 1.2 to 1.6. The sunscreen resin composition. The sunscreen resin composition according to claim 2, wherein the mode value is 0.2 to 1.0 μm. Content of the said small diameter titanium oxide particle and the content of the said large diameter titanium oxide particle is 5-30 mass parts and 5-50 mass parts with respect to 100 mass parts of the said thermoplastic resins, respectively. The sunscreen resin composition according to item 1. The sunscreen resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin is a polycarbonate or a fluororesin. The sunscreen resin composition according to any one of claims 1 to 5, wherein the titanium oxide particles are surface-treated with at least one of alumina and zirconia. The solar shading property according to any one of claims 1 to 6, which contains 0.01 to 5 parts by mass of at least one kind selected from an ultraviolet protective agent and a light stabilizer with respect to 100 parts by mass of the thermoplastic resin. Resin composition. 5 to 30 parts by mass of at least one flame retardant selected from a brominated flame retardant, a metal hydrate, a phosphate compound and ammonium polyphosphate with respect to 100 parts by mass of the thermoplastic resin. 7. The sunscreen resin composition according to any one of 7 above. 9. A mixture of a thermoplastic resin, small-diameter titanium oxide particles having an average particle diameter of 0.15 to 0.25 μm, and large-diameter titanium oxide particles having an average particle diameter of 0.40 to 0.45 μm. The sunscreen resin composition according to item 1.