JP2022167054A - Ultraviolet light source cover and ultraviolet light source unit - Google Patents

Abstract

To provide an ultraviolet light source cover and an ultraviolet light source unit which are formed of a material having high moldability.SOLUTION: There are provided an ultraviolet light source cover which contains a resin composition containing polyethylene or an ethylene-α-olefin copolymer, and has ultraviolet light transmittance at a wavelength of 235 nm of 40% or more; and an ultraviolet light source unit which includes the ultraviolet light source cover, and an ultraviolet light source installed in the ultraviolet light source cover.SELECTED DRAWING: None

Description

The present invention relates to an ultraviolet light source cover and an ultraviolet light source unit.

Ultraviolet rays are often used to kill bacteria and viruses. As such a technique, for example, Patent Literature 1 or 2 discloses a technique of irradiating ultraviolet rays using a mercury lamp or a UVC (ultraviolet rays of less than 280 nm) lamp. In recent years, LED lamps capable of irradiating deep ultraviolet rays have been put to practical use and their applications are expanding. In the UV LED lamp unit, the LED lamp itself is a point light source and there are wires that transmit power. is irradiated.

For example, in an ultraviolet sterilization apparatus, the ultraviolet LED lamp units are arranged on one side in the apparatus, and the ultraviolet sterilization is performed by irradiating the liquid passing through the container with ultraviolet rays.

JP-A-2006-116536 JP 2018-23923 A

In an ultraviolet light source unit having an ultraviolet light source and its cover, it is necessary for the ultraviolet light to be transmitted from the light source to the object in order for the ultraviolet light to reach the object to be irradiated. On the other hand, the cover for the ultraviolet light source is also required to have a protective function to prevent the light source from being damaged by contact with liquid or physical contact. Since ordinary glass, which is a transparent material, has a structure that absorbs ultraviolet rays, when ordinary glass is used as a cover material in an ultraviolet light source unit, the emitted ultraviolet rays are absorbed and the irradiated object is effectively irradiated with ultraviolet rays. I can't. Therefore, the materials for the cover are very limited, and for example, expensive quartz glass is used. However, quartz glass is inferior in formability and is limited to a flat plate shape. For this reason, in an ultraviolet light source unit in which an LED light source is covered with quartz glass, the LED light source is a point light source that can irradiate in all directions. Limited to directional illumination. For this reason, in such an ultraviolet light source unit, the irradiation efficiency is increased by applying a surface treatment to the inner surface of the container so that the emitted light can be totally reflected and collecting the emitted light on the window cover. There is room for improvement.

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned conventional improvements, and an object of the present invention is to provide an ultraviolet light source cover formed of a highly moldable material and an ultraviolet light source unit including the cover. .

As a result of extensive studies, the present inventors have found that the above problems can be solved by using a resin composition containing polyethylene or an ethylene α-olefin copolymer as a material for the ultraviolet light source cover, and have completed the present invention. was

That is, the present invention relates to the following.
[1]
Containing a resin composition containing polyethylene or an ethylene α-olefin copolymer,
An ultraviolet light source cover having an ultraviolet transmittance of 40% or more at a wavelength of 235 nm.
[2]
The ultraviolet light source cover according to [1], which has a visible light transmittance of 80% or more at a wavelength of 550 nm.
[3]
The ultraviolet light source cover according to [1] or [2], wherein the ultraviolet light source cover is a molded body of the resin composition.
[4]
The ultraviolet light source according to any one of [1] to [3], wherein the density of the resin composition measured according to D method of JIS K7112:1999 is 935 kg/m ³ or more and 965 kg/m ³ or less. cover.
[5]
The ultraviolet light source cover according to any one of [1] to [4], wherein the degree of orientation of the resin composition measured by wide-angle X-ray scattering measurement is 0.95 or more.
[6]
The ultraviolet light source cover according to any one of [1] to [5], wherein the degree of orientation of the resin composition measured by small-angle X-ray scattering measurement is 0.65 or more.
[7]
of [1] to [6], wherein the polyethylene or ethylene α-olefin copolymer contained in the resin composition has a long chain branching degree measured by ¹³ C-NMR of 0.13 or more and 2.00 or less. An ultraviolet light source cover according to any one of the above.
[8]
The ultraviolet light source cover according to any one of [1] to [7], wherein the ultraviolet light source cover has a thickness of 0.1 mm or more and 10 mm or less.
[9]
The ultraviolet light source cover according to any one of [1] to [8], wherein the resin composition contains substantially no additives.
[10]
The ultraviolet light source cover according to any one of [1] to [9], wherein the ultraviolet light source cover has a curved surface.
[11]
The ultraviolet light source cover according to any one of [1] to [10], wherein the ultraviolet light source cover is configured to be able to irradiate in an azimuth of 50% or more around the ultraviolet light source.
[12]
The ultraviolet light source cover according to any one of [1] to [11], which is for fluid sterilization.
[13]
the ultraviolet light source cover according to any one of [1] to [12];
an ultraviolet light source installed within the ultraviolet light source cover;
an ultraviolet light source unit.

ADVANTAGE OF THE INVENTION According to this invention, the ultraviolet light source unit containing the ultraviolet-light-source cover formed with the material with high moldability, and this cover is provided.

FIG. 1 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a flat ultraviolet light source cover. FIG. 2 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a hemispherical ultraviolet light source cover. FIG. 3 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a bullet-shaped ultraviolet light source cover. FIG. 4 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a spherical ultraviolet light source cover. FIG. 5 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having an elongated container-like ultraviolet light source cover. FIG. 6 is a schematic configuration diagram of an example of a fluid sterilization apparatus in which a large number of ultraviolet irradiation units of FIG. 5 are arranged. FIG. 7 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a flexible tubular ultraviolet light source cover.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail below. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Ultraviolet light source cover]
The ultraviolet light source cover of this embodiment contains a resin composition containing polyethylene or an ethylene α-olefin copolymer, and has an ultraviolet transmittance of 40% or more at a wavelength of 235 nm.

<Resin composition>
The resin composition used in this embodiment contains polyethylene or an ethylene α-olefin copolymer. The ultraviolet light source cover of the present embodiment can be obtained in a free shape by using such a resin composition having excellent shapeability. Therefore, the ultraviolet light source unit having the cover can widen the irradiation direction of the light source. Polyethylene is polymerized from ethylene, and ethylene α-olefin copolymer is polymerized from ethylene and α-olefin. Therefore, polyethylene or ethylene α-olefin copolymer does not contain aromatic rings, carbon-oxygen double bonds, and heteroatoms other than carbon and hydrogen, which are found in other resins, and therefore does not have a structure that absorbs ultraviolet rays. In addition, since the number of double bonds is usually very small, it is characterized in that molecular scission by ultraviolet light and oxidative degradation by oxygen in the air are unlikely to occur. On the other hand, the tertiary carbon, which is the branching point of the long-chain branch, has a relatively low carbon-carbon bond energy associated with the primary or secondary carbon, so linear polyethylene having no long-chain branch is preferred.

The polyethylene or ethylene α-olefin copolymer used in this embodiment is not particularly limited, but examples thereof include high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, and low-pressure linear low-density polyethylene. High-density polyethylene is preferable in terms of durability against external pressure when used as a cover, and strength for resisting external pressure deformation of a container containing an object to be irradiated and a molded product. Examples of the α-olefin forming the ethylene α-olefin copolymer include, but are not particularly limited to, propylene, 1-butene, and 1-hexene.

Since ultraviolet light has a large energy, it may deteriorate the base material of the cover or the container when the ultraviolet light is transmitted through the cover or the container. Therefore, it is preferable to use a resin that can suppress the deterioration of the base material as the ultraviolet light source cover. On the other hand, since the wavelength of ultraviolet rays is short, if the resin used for the cover or container has a structure larger than the wavelength of the ultraviolet rays, such as a crystalline structure, the ultraviolet rays will be scattered and it may be difficult for the ultraviolet rays to pass through effectively. be. In the case where the resin itself has a low ultraviolet transmittance, a thin film can be formed to achieve a sufficient amount of ultraviolet transmittance, but the strength is lowered. Therefore, an ethylene or α-olefin copolymer whose crystal structure is finely divided to the wavelength of ultraviolet rays can achieve a thickness and an ultraviolet transmission amount. Furthermore, in the ultraviolet light source cover of the present embodiment, if high-density polyethylene is used as the resin, it is excellent in strength even if it has a fine crystal structure.

The density of the resin composition used in this embodiment is 935 kg/m ³ or more and 965 kg/m ³ or less. When the density of the resin composition is 935 kg/m ³ or more, the impact strength of the ultraviolet light source cover tends to increase. On the other hand, when the resin composition has a density of 965 kg/m ³ or less, it has an appropriate elastic modulus, so that the ultraviolet light source cover tends to have excellent strength against impact. Also, good transparency can be obtained by setting the density of the polyethylene resin to 965 kg/m ³ or less in molding the cover by rolling and stretching the molded product. The density of linear polyethylenes such as high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) is known to depend on the amount of copolymer contained, with a tendency for the density to increase as the amount of copolymer decreases. It is in. When the molded product is rolled or stretched, it is preferable that the folded crystals having a lamellar structure are untied cleanly. The branched components come out from the folded crystals and become loose molecules or tie molecules, and during stretching, the adjacent crystals are loosened in order, and the crystal structure tends to disappear, resulting in a transparent molded product. However, if there is no copolymer and there is no branching component that connects the crystals, the crystals cannot be unraveled well by stretching, and crazes occur between the crystals, resulting in a decrease in transparency. Therefore, in order to obtain a transparent molded article, it is preferable to introduce a copolymer, which is a branching component, into the polyethylene resin to a certain extent so that the density of the resin composition is 965 kg/m ³ or less. From the above, the density of the resin composition is more preferably 940 kg/m ³ or more and 960 kg/m ³ or less, still more preferably 945 kg/m ³ or more and 960 kg/m ³ or less, and even more preferably 955 kg/m ³ or more. 960 kg/m ³ or less.

In the present embodiment, the density of the resin composition is measured according to D method (density gradient tube method) of JIS K7112:1999. Specifically, the density of the resin composition is measured by the method described in Examples below.

<Wide-angle X-ray scattering orientation degree>
The degree of orientation (hereinafter also referred to as “f ₁ ”) of the resin composition used in this embodiment as measured by wide-angle X-ray scattering measurement (hereinafter also referred to as “WAXS”) is preferably 0.95 or more. Increasing the degree of orientation indicated above tends to increase the strength of the UV light source cover. The degree of orientation of the resin composition used in the present embodiment by wide-angle X-ray scattering measurement is more preferably 0.960 or more, still more preferably 0.962 or more, and even more preferably 0, from the viewpoint of increasing strength. .964 or higher. Although the upper limit of the degree of orientation of the resin composition measured by wide-angle X-ray scattering measurement is not particularly limited, it is, for example, 1.0 or less.

In this embodiment, the degree of orientation of the resin composition by wide-angle X-ray scattering measurement can be measured by the method described in Examples below.

<Small-angle X-ray scattering orientation degree>
The degree of orientation (hereinafter also referred to as “f ₂ ”) of the resin composition used in the present embodiment by small-angle X-ray scattering measurement (hereinafter also referred to as “SAXS”) is preferably 0.65 or more. Increasing the degree of orientation indicated above tends to increase the strength of the UV light source cover. The degree of orientation of the resin composition used in the present embodiment by small-angle X-ray scattering measurement is more preferably 0.66 or more, still more preferably 0.68 or more, and even more preferably 0.70 or more. Although the upper limit of the degree of orientation of the resin composition measured by small-angle X-ray scattering measurement is not particularly limited, it is, for example, 1.0 or less.

In the present embodiment, the degree of orientation of the resin composition by small-angle X-ray scattering measurement can be measured by the method described in Examples below.

The above degree of orientation is the roll gap width, the roll temperature, the sheet temperature before rolling of the raw sheet, the temperature difference between the sheet and the roll, or the temperature difference between the raw sheet and the roll when rolling the sheet before molding the ultraviolet light source cover. It can be controlled by the ratio (rolling ratio) to the thickness of the sheet after rolling.

<Long chain branching degree>
The long chain branching degree measured by ¹³ C-NMR of the polyethylene or ethylene α-olefin copolymer contained in the resin composition used in the present embodiment is preferably 0.13 or more and 2.00 or less. Since the long chain branching degree of the ultraviolet light source cover of the present embodiment is within the range shown above, it tends to have a sufficient thickness and increased strength when a transparent member is molded by the following molding method. From the viewpoint of increasing the strength, the degree of long chain branching is more preferably 0.50 or more and 2.00 or less, still more preferably 0.50 or more and 1.80 or less, and even more preferably 1.00 or more and 1 .80 or less. In addition, in this embodiment, the degree of long chain branching can be measured by the method described in Examples below.

Since the residue of the catalyst used for polymerizing the resin can be the starting point of deterioration, the content of the catalyst residue in the resin used in the present embodiment is preferably as small as possible. In the resin composition used in the present embodiment, the content of the catalyst residue is defined by measuring the amount of metal derived from the catalyst in the resin, and the metal content is preferably 10 mass ppm or less, and 1 mass ppm or less. more preferred.

Heat stabilizers are usually added to resins to impart heat stability, and neutralizers are sometimes added to neutralize acidic catalyst residues, but the additive itself has a structure that absorbs ultraviolet rays, so the less the amount, the better. .

From the above viewpoints, it is preferable that the resin composition used in the present embodiment contains substantially no additives. Additives are not particularly limited except for catalysts, and include, for example, the above-mentioned neutralizers, heat stabilizers, ultraviolet absorbers, and the like. “Substantially free of additives” means that the total content of additives is 1% by mass or less with respect to the total mass of the resin composition. In addition, in the ultraviolet light source cover of the present embodiment, the total content of additives is more preferably 0.5% by mass or less, more preferably 0.1% by mass or less, relative to the total mass of the resin composition. and more preferably 0.01% by mass or less.

In the ultraviolet light source cover of the present embodiment, the content of polyethylene or ethylene α-olefin copolymer may be 80% by mass or more, or 90% by mass or more, relative to the total amount of the resin composition. , 98% by mass or more. The upper limit of the content of polyethylene or ethylene α-olefin copolymer is not particularly limited, but is, for example, 100% by mass based on the total amount of the resin composition.

<Ultraviolet transmittance at a wavelength of 235 nm>
The UV light source cover of this embodiment has a UV transmittance of 40% or more at a wavelength of 235 nm. The transmittance of ultraviolet rays at a wavelength of 235 nm is preferably 45% or more, more preferably 50% or more. Although the upper limit of the transmittance of ultraviolet rays at a wavelength of 235 nm is not particularly limited, it is, for example, 100%. When the UV light transmittance of the UV light source cover at a wavelength of 235 nm is within the above range, the UV light source unit having the cover can efficiently irradiate the object with UV light.

<Ultraviolet transmittance at a wavelength of 265 nm>
The UV light transmittance of the UV light source cover of this embodiment at a wavelength of 265 nm is preferably 50% or more, more preferably 60% or more, and more preferably 70% or more. Although the upper limit of the transmittance of ultraviolet rays at a wavelength of 265 nm is not particularly limited, it is, for example, 100%. When the UV light transmittance at a wavelength of 265 nm of the UV light source cover is within the above range, the UV light source unit having the cover tends to be able to efficiently irradiate the object with UV light.

<Visible light transmittance at a wavelength of 550 nm>
The visible light transmittance of the ultraviolet light source cover of the present embodiment at a wavelength of 550 nm is preferably 80% or higher, more preferably 85% or higher, and more preferably 90% or higher. Although the upper limit of the visible light transmittance at a wavelength of 550 nm is not particularly limited, it is, for example, 100%. When the visible light transmittance of the ultraviolet light source cover at a wavelength of 550 nm is within the above range, the ultraviolet light source unit having the cover tends to allow visual confirmation of the state of the light source inside the cover.

The transmittance described above can be measured in accordance with JIS K 7136:2000 at the thinnest portion of the ultraviolet light source cover. As a measuring instrument, for example, a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. can be used. Specifically, it can be measured by the method described in Examples below.

The method for controlling the transmittance of the ultraviolet light source cover within the above range is not particularly limited. A method of appropriately adjusting the processing conditions for molded articles of these resin compositions can be mentioned.

A specific example of the method for controlling the transmittance of the ultraviolet light source cover within the above range by appropriately adjusting the processing conditions of the molded product of the resin composition is not particularly limited, but includes the following method.

Since polyethylene and ethylene-α-olefin copolymers are crystalline resins and have a spherulite structure, they tend to scatter short-wavelength light and are sometimes opaque from visible light to ultraviolet light. There are several methods for making opaque polyethylene and ethylene-α-olefin copolymer transparent to control the transmittance of the UV light source cover within the above range. Specific examples include, but are not limited to, a method of remarkably lowering the density of polyethylene and ethylene-α-olefin copolymer to make spherulites finer. However, although polyethylene and ethylene-α-olefin copolymer with fine spherulites have a certain degree of UV transmittance, they tend to have a large decrease in strength due to their low density. Therefore, it is preferable to use another method when strength is particularly required for the ultraviolet light source cover. Further, for example, a method of forming a film from polyethylene and ethylene-α-olefin copolymer by ordinary inflation molding or sequential stretching can also be used. Such film-like moldings tend to have improved transparency due to their thinness and cold stretching. However, with this method, it is difficult to obtain a molded body having a thickness of 50 μm or more, and the shape of the molded body is limited to a flat surface or a bag-like shape, which tends to be low in strength and susceptible to deformation. Therefore, as a more effective method for controlling the transmittance of the ultraviolet light source cover within the above range, there is no particular limitation, but for example, a sheet, rod, or molded article once molded from polyethylene and ethylene-α-olefin copolymer is treated with the melting point of At a temperature 2° C. to 10° C. lower than that, rolling, tensile drawing or plugging, push rod drawing and air blow molding can be mentioned. In particular, by molding a resin composition having a density of 965 kg/m ³ or less by such a method, it is possible to obtain a molded product that is transparent to ultraviolet rays while maintaining the thickness, and the transmittance of the ultraviolet light source cover is can be controlled within the above range. The molded article obtained by such a method has extremely high transparency from visible light to ultraviolet rays, and tends to have high strength because it can be made thick.

The ultraviolet light source cover of this embodiment is preferably a molding of a resin composition containing polyethylene or an ethylene α-olefin copolymer.

The shape of the ultraviolet light source cover of this embodiment is not particularly limited, but examples thereof include a flat plate, hemispherical shape, cup shape, and elongated shape. A flat UV light source cover can be obtained, for example, by rolling or stretching a flat sheet, or from a flat portion of a molded body. A hemispherical, cup or elongated ultraviolet light source cover can be obtained by drawing from a sheet with a plug or push rod and blowing air.

The method for manufacturing the ultraviolet light source cover of the present embodiment is not particularly limited. 10 ° C. lower molding temperature), or the cooled sheet is heated from normal temperature to the melting point T ° C. of the sheet within a predetermined time (20 to 200 seconds) (preferably 2 to 10 ° C. from the melting point T ° C. low temperature), and the temperature control range of the product intermediate is within the melting point T ° C. ± 10% of the sheet, and the molded body (for example, , clear cup). After uniaxial stretching with a plug or push rod, further air blowing in the cavity enables stretching in a direction different from that of the plug or push rod (biaxial stretching), resulting in a molded product. The relaxation of the orientation improves the dimensional stability and transparency of the body, and also improves the impact resistance.

In another form, the sheet, pipe, or profile extrudate is not cooled to room temperature as it is (preferably kept at a molding temperature 2 to 10 ° C. lower than the melting point T ° C. of the extrudate), or the cooled extrudate is subjected to a predetermined temperature. Within the time (20 to 200 seconds), the temperature is raised from room temperature to the melting point T ° C of the extruded product (preferably a temperature 2 to 10 ° C lower than the melting point T ° C), and the temperature control range of the intermediate product is extruded. The extruded product has a melting point T°C within ±10%, and includes a step of rolling with rolling rolls controlled at a temperature 2 to 10°C lower than the melting point T°C of the extrudate.

In still another embodiment, the bottle molded by blow molding or the bottomed parison molded by injection molding is not cooled to room temperature as it is (preferably, the molding temperature is kept 2 to 10 ° C. lower than the melting point T ° C. of the extruded product), Alternatively, the cooled extrudate is raised to a temperature from room temperature to the melting point T ° C. of the extrudate (preferably 2 to 10 ° C. lower than the melting point T ° C.) within a predetermined time (20 to 200 seconds), and the product It has a step in which the temperature control range of the intermediate is within the melting point T ° C of the extruded product ± 10%, and the temperature is controlled to be 2 to 10 ° C lower than the melting point T ° C of the extruded product. / Or includes a step of stretching by blowing air. The speed at which the push rod or plug pushes the sheet is not particularly limited, but is preferably 15,000 mm/sec or more, more preferably 29,400 mm/sec or more, because the faster the speed, the shorter the molding cycle.

Next, the structure of the ultraviolet light source cover of this embodiment will be described.
The thickness of the ultraviolet light source cover of this embodiment is preferably 0.1 mm or more and 10 mm or less. The ultraviolet light source cover of the present embodiment exhibits excellent strength because the thickness is within this range. In addition, in this embodiment, the thickness means the thickness of the thinnest portion. From the viewpoint of improving the strength, the thickness is more preferably 0.1 mm or more and 5 mm or less, still more preferably 0.2 mm or more and 3 mm or less, and even more preferably 0.3 mm or more and 1 mm or less.

The ultraviolet light source cover of this embodiment preferably has a curved surface from the viewpoint of widening the irradiation surface. Moreover, it is preferable that the ultraviolet light source cover of the present embodiment is configured to be able to irradiate in an azimuth of 50% or more around the ultraviolet light source. In the present embodiment, the azimuth of 50% or more around the ultraviolet light source refers to the coverage rate covered by the ultraviolet light source cover with reference to the center of the light source inside the ultraviolet light source unit to which the ultraviolet light source cover is attached.

Moreover, it is preferable that the ultraviolet light source cover of this embodiment is for fluid sterilization. Since the ultraviolet light source cover of this embodiment has excellent moldability, it can be molded into a structure with a high curvature. Therefore, it can be molded into a shape such as a tube, and tends to increase the light irradiation area to the fluid.

The ultraviolet light source cover of this embodiment can be suitably used for an ultraviolet light source unit.

The ultraviolet light source unit of this embodiment includes, for example, the ultraviolet light source cover described above and an ultraviolet light source installed within the ultraviolet light source cover.

The ultraviolet light source is not particularly limited, and examples thereof include ultraviolet LEDs.

In conventional irradiation equipment, light source units with window glass are lined up in the container part inside the equipment, and ultraviolet rays are irradiated by flowing inside the equipment, which makes the equipment large and efficient for the contents There is room for improvement as irradiation is not possible. It is preferable that the case of the ultraviolet ray cover or the irradiation unit is made of resin because it is inexpensive, has excellent productivity, is lightweight, and can be easily given various shapes and is hard to break. However, many resins have a structure that absorbs ultraviolet light in their structure, and are therefore opaque to ultraviolet light, and are susceptible to deterioration due to their structure. On the other hand, the ultraviolet light source cover of the present embodiment contains a resin containing polyethylene or an ethylene α-olefin copolymer and has a transmittance of 40% or more for ultraviolet rays at a wavelength of 235 nm, thereby solving the problem.

Examples of the ultraviolet light source cover and the ultraviolet light source unit according to this embodiment will be described more specifically based on the drawings.

FIG. 1 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a flat ultraviolet light source cover. In FIG. 1, reference numeral 11 denotes a light source (LED chip) of an ultraviolet LED lamp, which is installed in a substrate 13. As shown in FIG. In FIG. 1, reference numeral 12 denotes an ultraviolet light source cover that is transparent to ultraviolet rays, and is placed on the substrate 13 to seal the LED itself or protect the LED unit. Since the ultraviolet light source cover 12 must be transparent to ultraviolet rays, it is not possible to use many transparent resins, and conventionally quartz glass is generally used. In the ultraviolet light source cover of this embodiment, this can be a resin containing polyethylene or an ethylene α-olefin copolymer. The conventional ultraviolet light source cover using quartz glass is limited to a flat plate shape as shown in FIG. .

On the other hand, since the ultraviolet light source cover of the present embodiment is made of a resin having excellent moldability, it can be molded into a structure having a high curvature as shown in FIGS.

FIG. 2 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a hemispherical ultraviolet light source cover. The ultraviolet LED lamp unit shown in FIG. 2 has an LED chip 21 installed above a substrate 23 and protected by a hemispherical ultraviolet light source cover 22, and can emit light at an angle of 180° or more from the light source. .

FIG. 3 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a bullet-shaped (cup-shaped) ultraviolet light source cover. Although it is difficult to make a shell-shaped ultraviolet light source cover with quartz glass, the ultraviolet light source cover of the present embodiment uses a resin containing polyethylene or ethylene α-olefin copolymer, so that it has excellent moldability and can be used as a shell. type ultraviolet light source cover. The ultraviolet LED lamp unit shown in FIG. 3 has a light source (LED chip) 31 of the ultraviolet LED lamp covered with a bullet-shaped ultraviolet light source cover 32, and emits light at a wider angle than the ultraviolet LED lamp unit shown in FIG. can do.

FIG. 4 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having a spherical ultraviolet light source cover. The ultraviolet LED lamp unit shown in FIG. 4 has a plurality of ultraviolet LED lamp light sources (LED chips) 41 integrated and covered with a spherical ultraviolet light source cover 42, and can irradiate in almost all directions.

FIG. 5 is a schematic cross-sectional view of an example of an ultraviolet LED lamp unit having an elongated container-like ultraviolet light source cover. The ultraviolet LED lamp unit shown in FIG. 5 is an ultraviolet light source unit in which an ultraviolet LED lamp light source (LED chip) 51 is installed at the tip of an elongated container-like ultraviolet light source cover 52 .

The ultraviolet light source unit of this embodiment is preferably applied to a fluid sterilizer.

The fluid sterilizer of the present embodiment includes a flow path through which fluid passes, the ultraviolet light source cover arranged in the flow path, and an ultraviolet light source installed in the ultraviolet light source cover.

FIG. 6 is a schematic configuration diagram of an example of a fluid sterilization device 63 in which a large number of ultraviolet irradiation units 61 of FIG. 5 are arranged. In the fluid sterilizer shown in FIG. 6, the liquid is circulated from one side in the direction of the arrow in FIG.

In addition to the above applications, as shown in FIG. 7, an ultraviolet irradiation unit in which an ultraviolet LED lamp light source (LED chip) 71 is placed in a flexible tube-shaped ultraviolet light source cover 72 can be used to It can be used for ultraviolet irradiation of the part.

EXAMPLES The present embodiment will be described in more detail with reference to Examples below, but the present embodiment is not limited to these Examples.

In the present examples, measurement and evaluation of each physical property were performed by the following methods.

<Density>
Density was measured according to D method of JIS K7112:1999. Specifically, the strand used for the MFR measurement was annealed at 120° C. for 1 hour, allowed to cool for 1 hour, and the density was measured using a density gradient tube.

<Long chain branching degree>
The degree of long-chain branching of the polyethylene or ethylene α-olefin copolymer contained in the resin composition was measured by ¹³ C-NMR using an AVANCE 600 MHz nuclear magnetic resonance device manufactured by BRUKER BIO SPIN to measure the number of branches of hexyl groups or more. I asked. In the measurement, ortho-dichlorobenzene-d ₄ was used as the solvent, and the number of accumulations was 8000. As the number per 1000 main chain methylene carbons (chemical shift: 29.9 ppm), branching degree from the integrated value of the peak of β-carbon (22.7 ppm) at the β position of the tertiary carbon at the branch point of long chain branching asked for

<Wide-angle X-ray scattering orientation degree>
Using the smooth surface of the molded body as a test piece, WAXS (Nano Viewer) manufactured by Rigaku was used to determine the orientation degree (wide-angle X-ray scattering orientation degree) of the resin composition by wide-angle X-ray scattering measurement under the following conditions. As an optical system, point collimation (1st: 0.4 mmφ, 2nd: 0.2 mm, guard: 0.6 mmφ) was used, and X-rays were made incident (Through View) from the sheet normal direction. Using an imaging plate as a detector, camera length: 78.8 mm, measurement time: irradiation for 15 minutes, a ring-averaged WAXS profile scattering image was obtained. From the obtained ring-averaged WAXS profile, the range of 2θ is 21.0 ° < 2θ < 22.0 ° is integrated from the azimuth angle dependence of the peak (2θ = 21.2 °) intensity derived from the (110) plane. , Fitting the 180 ° or 0 ° (360 °) peak from the relationship diagram of the azimuth angle and normalized scattering intensity with a Gaussian function, determining the half width (Δ) of the obtained peak, and calculating formula (1) The degree of orientation f was determined by
f=1-(Δ/360°) Equation (1)

<Small-angle X-ray scattering orientation degree>
The orientation degree of the resin composition measured by small-angle X-ray scattering measurement (small-angle X-ray scattering orientation degree) was determined by small-angle X-ray diffraction (scattering) analysis (SAXS) of the molded body. The measurement equipment and conditions were as follows.
Apparatus: Nano Viewer (manufactured by Rigaku Corporation)
Conditions Optical system: Point collimation X-ray incident direction: Film normal direction Measurement time: 900 seconds Temperature: Normal temperature Sample shape: Sheet Camera length: 647.4 mm
Detector: PILATUS100K (two-dimensional detector)
X-ray wavelength λ: 0.154 nm

<Transmittance>
The total light transmittance (transmittance at wavelengths of 235 nm, 265 nm and 550 nm) of the ultraviolet light source covers produced in Examples and Comparative Examples was measured according to JIS K 7136:2000. A haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used as a measuring instrument.

<Haze>
The haze of the sheets produced in Examples and Comparative Examples (the haze of the sheet before shaping) and the haze of the ultraviolet light source cover molded from the sheet (the haze of the cover after shaping) were measured according to JIS K 7136:2000. It was measured. A haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used as a measuring instrument.

<thickness>
The wall thickness of the cup-shaped ultraviolet light source cover sample shown in FIG.

<Strength>
A 50 g weight was dropped from a height of 20 cm onto the apex of the spherical part of the cup-shaped ultraviolet light source cover produced in Examples and Comparative Examples shown in FIG.
(Evaluation criteria)
A: no dent B: dent but no destruction or cracking C: destruction or cracking but the weight does not penetrate the cover.
D: The weight penetrates the cover

[Preparation example of polyethylene resin composition (PE1)]
(1) Synthesis of chromium oxide catalyst (I) A solution was obtained by dissolving 4 mol of chromium trioxide in 80 liters of distilled water. 20 kg of silica (grade 952 manufactured by WR Grace and Company) was immersed in this solution and stirred at room temperature for 1 hour to obtain a slurry. Thereafter, this slurry was heated to distill off water, and then dried under reduced pressure at 120° C. for 10 hours. After that, it was calcined at 600° C. for 5 hours with dry air flowing to obtain a chromium oxide catalyst (I) containing 1.0% by mass of chromium.

(2) Synthesis of organoaluminum compound (II) 100 mols of triethylaluminum, 100 mols of methylhydropolysiloxane (viscosity at 30°C: 30 centistokes) (based on Si), and 150 liters of n-hexane were weighed in a pressure vessel under a nitrogen atmosphere. The solution was taken out and reacted at 90° C. for 5 hours with stirring to prepare a hexane solution of Al(C ₂ H ₅ ) ₂ (OSi.H.CH ₃ .C ₂ H ₅ ). 100 mol (based on Al) of this solution was then transferred to a 600 liter reactor under a nitrogen atmosphere, and 100 mol (based on Al) of Al(C ₂ H ₅ ) ₂ Al(O—C ₂ H ₅ ) and 50 mol of n-hexane were added. liters of the mixture is added with stirring at 80° C. and reacted for 3 hours to form Al(C ₂ H ₅ ) _2.0 (OC ₂ H ₅ ) _0.5 (OSi.H.CH ₃ .C ₂ H ₅ ) _0.5 . A hexane solution (organoaluminum compound (II)) was prepared.

(3) Synthesis of Titanium Catalyst (III) A 15-liter reactor fully purged with nitrogen was charged with 3 liters of a 2 mol/liter n-heptane solution of trichlorosilane. The solution in the reactor was kept at −10° C. with stirring, and 7 liters of n-hexane solution of an organomagnesium component represented by the compositional formula AlMg ₆ (C ₂ H ₅ ) ₃ (n—C ₄ H ₉ ) ₆ (magnesium 5 mol in terms of conversion) was added over 3 hours, and the reaction was further stirred at 65° C. for 1 hour. After the reaction was completed, the supernatant was removed and washed four times with 7 liters of n-hexane to obtain a solid material slurry. A solid (titanium catalyst (III)) was separated from this solid material slurry, dried, and analyzed to find that it contained 20.3% by mass of titanium.

(4) Production of Polyethylene Resin A Polymerization was carried out in a 230-liter polymerization vessel in a single-stage polymerization process. The polymerization temperature was 84° C. and the polymerization pressure was 0.98 MPa. 50 g of the chromium oxide catalyst (I) synthesized in (1) and 0.03 mol (based on Al) of the organoaluminum compound (II) prepared in (2) were added to the polymerization vessel and allowed to react at room temperature for 1 hour. A solid catalyst was obtained. The resulting solid catalyst was reacted with ethanol and triethylaluminum at a rate of 2 g/hour at a molar ratio of 0.98:1 to obtain an organoaluminum compound. The obtained organoaluminum compound was supplied and adjusted so that the concentration in the polymerization vessel was 0.08 mmol/liter. Purified hexane was supplied at a rate of 60 liters/hour, ethylene was supplied at a rate of 10 kg/hour, and hydrogen was supplied as a molecular weight modifier so that the gas phase concentration was about 5 mol %, and polymerization was carried out. A polyethylene resin A (hereinafter also referred to as “resin A”) having an index (MI) of 1.0 g/10 min and a density of 960 kg/m ³ was produced.

(5) Production of polyethylene resin B First, in order to produce a low-molecular-weight component in the first-stage polymerization, a stainless steel polymerization vessel 1 with a reaction volume of 300 liters is used, and polymerization is performed under the conditions of a polymerization temperature of 83°C and a polymerization pressure of 1 MPa. did As catalysts, 1.4 millimoles (based on Ti atoms)/hour of the above solid catalyst (III), 10 millimoles (based on metal atoms)/hour of triisobutylaluminum, and 40 liters/hour of hexane were introduced. Hydrogen was used as the molecular weight modifier, and polymerization was carried out by supplying hydrogen so that the concentration of hydrogen with respect to ethylene was 70 mol %. The polymer slurry solution in the polymerization vessel 1 was led to a flash drum having a pressure of 0.1 MPa and a temperature of 75° C., and after unreacted ethylene and hydrogen were separated, it was introduced into the polymerization vessel 2 having a reaction volume of 250 liters with a slurry pump under pressure. . In the polymerization vessel 2, under conditions of a temperature of 77° C. and a pressure of 0.5 MPa, triisobutylaluminum was introduced at a rate of 23 mmol/hour and hexane at a rate of 95 liters/hour. To this, ethylene, hydrogen, and butene-1 were introduced so that the gas phase concentration of hydrogen was about 9 mol% and the gas phase concentration of butene was about 10 mol%. Polyethylene having a MI of 0.43 g/10 min and a density of 940 kg/m ³ is polymerized so that the mass ratio of the high molecular weight portion generated in the polymerization vessel 2 is 1.0 times the amount. A resin B (hereinafter also referred to as "resin B") was produced. The low molecular weight fraction produced in the polymerization vessel 1 had an MI of 70 g/10 min and a density of 972 kg/m ³ .

(6) Production of polyethylene resin composition (PE1) The powders of polyethylene resins A and B produced as described above were mixed at a mass ratio of 39:61, and then 300 ppm of calcium stearate and ADEKA Co., Ltd. were added to the mixture. 300 ppm of ADEKA STAB (registered trademark) AO-50 and 500 ppm of ADEKA STAB (registered trademark) 2112 were added and mixed by stirring with a mixer. Using a twin-screw extruder with a cylinder diameter of 44 mm (TEX44HCT-49PW-7V manufactured by Japan Steel Works, Ltd.), this mixture was subjected to conditions of a cylinder temperature of 200 ° C. and an extrusion rate of 35 kg / hour to obtain a polyethylene resin composition (PE1). rice field.

[Preparation example of polyethylene resin composition (PE2)]
(1) Preparation of supported metallocene catalyst [A] Silica (P-10, manufactured by Fuji Silysia Co., Ltd. (Japan)) was calcined at 400°C for 5 hours in a nitrogen atmosphere and dehydrated. Ethoxydiethylaluminum was reacted with surface hydroxyl groups to generate ethane gas, and the amount of ethane gas generated was measured using a gas burette. The initial amount of hydroxyl groups on the surface of the dehydrated silica was found to be 1.3 mmol/g-SiO ₂ based on the amount of ethane gas generated. In an autoclave with a volume of 1.8 liters, 40 g of this dehydrated silica was dispersed in 800 cc of hexane to obtain a slurry. 60 cc of a hexane solution of triethylaluminum (concentration: 1 mol/liter) was added to the obtained slurry while maintaining the temperature at 50° C. while stirring. The solution in the autoclave is then stirred for 2 hours to react the triethylaluminum with the surface hydroxyl groups of the silica, containing the triethylaluminum-treated silica and the supernatant, wherein all the surface hydroxyl groups of the triethylaluminum-treated silica are triethylaluminum. A component [D] capped with aluminum was obtained. After that, the unreacted triethylaluminum in the supernatant was removed by removing the supernatant in the obtained reaction mixture by decantation. Then, an appropriate amount of hexane was added to obtain 800 cc of hexane slurry of triethylaluminum-treated silica. On the other hand, 200 mmol of [(Nt-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]titanium-1,3-pentadiene (hereinafter referred to as “titanium complex”) was added to Isopar E [Exxon Chemical Co. (USA). )] A 1 mol/liter hexane solution of AlMg ₆ (C ₂ H ₅ ) ₃ (n—C ₄ H ₉ ) ₁₂ previously synthesized from triethylaluminum and dibutylmagnesium dissolved in 1000 cc. was added, and hexane was further added to adjust the titanium complex concentration to 0.1 mol/liter to obtain component [E].
Further, 5.7 g of bis(hydrogenated tallowalkyl)methylammonium-tris(pentafluorophenyl)(4-hydroxyphenyl)borate (hereinafter abbreviated as "borate") was added to 50 cc of toluene and dissolved to obtain the borate. A 100 mmol/l toluene solution was obtained. To this borate toluene solution, 5 cc of a 1 mol/liter hexane solution of ethoxydiethylaluminum was added at room temperature, and hexane was further added to adjust the borate concentration in the toluene solution to 70 mmol/liter. Then, the mixture was stirred at room temperature for 1 hour to obtain a reaction mixture containing borate.
46 cc of this reaction mixture containing borate was added to 800 cc of the slurry of component [D] obtained above with stirring at 15 to 20° C., and the borate was supported on silica by physical adsorption. Thus, a slurry of silica supporting borate was obtained. Further, 32 cc of the component [E] obtained above was added and stirred for 3 hours to allow the titanium complex and the borate to react. Thus, a metallocene-supported catalyst [A] containing silica and a supernatant liquid and having catalytically active species formed on the silica was obtained.

(2) Preparation of Liquid Promoter Component [B] As an organomagnesium compound, an organomagnesium compound represented by AlMg ₆ (C ₂ H ₅ ) ₃ (nC ₄ H ₉ ) ₁₂ was used. Methylhydropolysiloxane (viscosity 20 centistokes at 25° C.) was used as the siloxane compound to react with. In a 200 cc flask, 40 cc of hexane and AlMg ₆ (C ₂ H ₅ ) ₃ (nC ₄ H ₉ ) ₁₂ were added with stirring to give a total amount of 37.8 mmol of Mg and Al, and methyl hydropolyethylene was prepared at 25°C. 40 cc of hexane containing 2.27 g (37.8 mmol) of siloxane was added with stirring to obtain a solution. Thereafter, the obtained solution was heated to 80° C. and reacted with stirring for 3 hours to prepare a liquid cocatalyst component [B].
Using a combination of the metallocene-supported catalyst [A] and the liquid promoter component [B] as a metallocene catalyst, a metallocene catalyst-based high-density polyethylene was prepared as follows.

(3) Production of polyethylene resin composition (PE2) Using the metallocene catalyst obtained above, two-stage polymerization was carried out in two polymerization tanks connected in series by a continuous slurry polymerization method. The comonomer used is 1-butene. In the first-stage polymerization tank, only ethylene was supplied as a monomer, the temperature was 70° C., hydrogen was supplied as a molecular weight modifier at a rate of 1.01 mol %, and the total pressure was maintained at 3.0 kg/cm ² G. In the second stage, 0.23 mol % of 1-butene and 550 mol ppm of hydrogen were supplied at a temperature of 75° C., and polymerization was carried out by maintaining the total pressure at 6.2 kg/cm ² G. The ratio of the production amount of the low-molecular-weight component (A) composed of the ethylene homopolymer obtained in the first-stage polymerization tank is 70% by mass, and the high-molecular-weight component (B) composed of the copolymer obtained in the second-stage polymerization tank was set to 30% by mass. In this way, a powder of metallocene catalyst-based high-density polyethylene (hereinafter also referred to as "resin C") was obtained. Using a twin-screw extruder (manufactured by Nippon Steel Corporation; TEX44HCT-49PW-7V), the obtained resin C powder was extruded while kneading under the conditions of a cylinder temperature of 200 ° C. and an extrusion rate of 35 kg / hour, to obtain a polyethylene resin composition ( PE2) pellets were obtained.

[Example 1]
(1) Preparation of sheet As shown in Table 1, the polyethylene resin composition (PE1) prepared above was used and heated and melted at a temperature of 200°C by compression molding to prepare a sheet of 300 mm square and 1.2 mm in thickness.

(2) Ultraviolet light source cover molding The sheet prepared in (1) above is clamped and heated between heaters so that the temperature of the sheet is 5 to 10°C lower than the melting point (Tm) of the resin, forming a cup-shaped cavity. A cup-shaped ultraviolet light source cover as shown in FIG. 3 was formed by pushing a push rod from above at a speed of 15000 mm/sec and blowing in air. Using the obtained ultraviolet light source cover, each physical property was measured and evaluated by the above methods. Table 2 shows the results.

[Example 2]
As the resin composition forming the ultraviolet light source cover, as shown in Table 1, a cup-shaped ultraviolet light source cover was molded in the same manner as in Example 1 except that the polyethylene resin composition (PE2) prepared above was used. Using the obtained ultraviolet light source cover, each physical property was measured and evaluated by the above methods. Table 2 shows the results.

[Example 3]
As the resin composition forming the ultraviolet light source cover, as shown in Table 1, a cup-shaped cup was formed in the same manner as in Example 1, except that Suntech (registered trademark)-HD B161 (high-density polyethylene) manufactured by Asahi Kasei Corporation was used. A UV light source cover was molded. Using the obtained ultraviolet light source cover, each physical property was measured and evaluated by the above methods. Table 2 shows the results.

[Example 4]
As the resin composition forming the ultraviolet light source cover, as shown in Table 1, a cup-shaped cup was formed in the same manner as in Example 1, except that Suntech (registered trademark)-HD B870 (high-density polyethylene) manufactured by Asahi Kasei Corporation was used. A UV light source cover was molded. Using the obtained ultraviolet light source cover, each physical property was measured and evaluated by the above methods. Table 2 shows the results.

[Comparative Example 1]
As the resin composition forming the ultraviolet light source cover, as shown in Table 1, a cup-shaped cup was formed in the same manner as in Example 1, except that Suntech (registered trademark)-HD J240 (high-density polyethylene) manufactured by Asahi Kasei Corporation was used. A UV light source cover was molded. Using the obtained ultraviolet light source cover, each physical property was measured and evaluated by the above methods. Table 2 shows the results.

Claims (13)

Containing a resin composition containing polyethylene or an ethylene α-olefin copolymer,
An ultraviolet light source cover having an ultraviolet transmittance of 40% or more at a wavelength of 235 nm. 2. The ultraviolet light source cover according to claim 1, which has a visible light transmittance of 80% or more at a wavelength of 550 nm. The ultraviolet light source cover according to claim 1 or 2, wherein the ultraviolet light source cover is a molded body of the resin composition. The ultraviolet light source according to any one of claims 1 to 3, wherein the resin composition has a density of 935 kg/m ³ or more and 965 kg/m ³ or less, as measured according to D method of JIS K7112:1999. cover. The ultraviolet light source cover according to any one of claims 1 to 4, wherein the degree of orientation of the resin composition measured by wide-angle X-ray scattering measurement is 0.95 or more. The ultraviolet light source cover according to any one of claims 1 to 5, wherein the resin composition has an orientation degree of 0.65 or more by small-angle X-ray scattering measurement. 7. Any one of claims 1 to 6, wherein the polyethylene or ethylene α-olefin copolymer contained in the resin composition has a long chain branching degree measured by ¹³ C-NMR of 0.13 or more and 2.00 or less. 2. The ultraviolet light source cover according to item 1. The ultraviolet light source cover according to any one of claims 1 to 7, wherein the ultraviolet light source cover has a thickness of 0.1 mm or more and 10 mm or less. 9. The ultraviolet light source cover of any one of claims 1-8, wherein the resin composition is substantially free of additives. 10. The ultraviolet light source cover of any one of claims 1-9, wherein the ultraviolet light source cover has a curved surface. 11. The ultraviolet light source cover according to any one of claims 1 to 10, wherein the ultraviolet light source cover is configured to be capable of being irradiated in azimuths of 50% or more around the ultraviolet light source. 12. An ultraviolet light source cover according to any one of claims 1 to 11 for fluid sterilization. an ultraviolet light source cover according to any one of claims 1 to 12;
an ultraviolet light source installed within the ultraviolet light source cover;
an ultraviolet light source unit.

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