JP2016218277A - Reflection sheet including surface projection and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a diffuse reflection factor without only simply increasing a reflection factor, and to provide a material that is high in strength, can retain durability in a harsh application, and can be simply manufactured.SOLUTION: Reflection tape 1 reflects light from a light source toward periphery. The reflection tape 1 is made by stretching olefin resin film including a large number of fillers 12a. The fillers 12a are larger in specific gravity than olefin resin and high in rigidity. On the basis of stretching, voids 13 are formed around the fillers 12a, and due to thinning of the film, a large number of surface projections 14 having the fillers 12a and the voids 13 as cores are formed on the surface of the tape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reflective sheet having high reflectance, particularly diffuse reflectance.

Reflective sheets for construction and agriculture require materials with high light shielding properties in order to prevent temperature rise in buildings and structures. Moreover, in the reflection sheet | seat etc. for agriculture, the material with a high diffuse reflectance is calculated | required from a viewpoint of the light supply to cultivated plants etc.

  As a reflection sheet for increasing the reflectance, there is a proposal of a technique for improving the coloring of fruits by reflecting sunlight with a reflection sheet in which an aluminum vapor deposition film is laminated as in Patent Document 1. However, the aluminum vapor deposition film reflects solar light specularly, but hardly diffusely reflects, so that there is a problem that the reflected light is concentrated in one direction and cannot be irradiated uniformly.

  In order to increase the diffuse reflectance, there is a proposal of a technique in which a large number of fine bubbles or pores are included in the sheet as in Patent Document 2. Both the total reflectance and the diffuse reflectance are highly effective. However, since the reflection on the sheet surface is specular reflection, in order to have a high diffuse reflectance as a whole, it is necessary to include a large number of bubbles or pores inside, and the strength becomes weak and the sheet thickness is limited. There is a problem.

In order to increase the diffuse reflectance, there are proposals of techniques for forming convex portions on the surface (Patent Documents 3 and 4). However, both are techniques for forming convex portions on the surface with a multilayer structure. That is, Patent Document 3 has a structure in which a resin layer is laminated on the surface of a base film, and the resin layer needs to contain a filler having a particle size larger than the thickness of the surface resin layer. Further, Patent Document 4 forms a convex portion in such a manner that an unstretched film comprising a three-layer structure of a central reflective layer and skin layers on both surfaces is stretched after pressing and protrudes from the surface layer. This is a structure in which voids are formed only on the surface.

In addition to patent documents, there is a nonwoven fabric sheet having a high diffuse reflectance obtained by laminating ultrafine polyethylene fibers randomly and bonding them only by heat and pressure. However, the nonwoven fabric has insufficient strength, and there is a problem of durability in applications such as agricultural sheets installed on the ground.

Actual opening H06-50432 JP 2009-225707 A JP 2006-15680 A JP 2014-119747 A

  The present invention aims to increase not only the reflectance but also the diffuse reflectance.

Another object of the present invention is to provide a material that can maintain durability even in severe and severe applications and that can be easily manufactured. Furthermore, it aims at provision of the material with an insect repellent effect.

In order to solve the above problems, according to the present invention,
A tape that reflects light from a light source to the surroundings, wherein the reflective tape is a tape obtained by stretching an olefin resin film containing a large number of fillers, and the filler has a specific gravity greater than that of the olefin resin and has a rigidity. It is a high substance, a void is formed around the filler based on the stretching, and a large number of the filler and the void are cores on the surface of the tape along with the thinning of the film based on the stretching. A stretched reflective tape is provided in which protrusions are formed.

  By stretching the olefin resin film, the olefin resin flows and the film becomes thin. Since the included filler has a higher specific gravity and higher rigidity than the olefin resin, it does not follow the flow of the olefin resin as it is, and is hardly deformed. For this reason, voids (voids) based on the difference in fluidity between the olefin resin and the filler are generated around the filler, and the surface portion of the stretched tape where the filler is located is swollen by the fluid force due to stretching to form a protrusion. It will be. Olefin resins have a small specific gravity (about 0.9) among synthetic resins and are excellent in injection fluidity. Here, the filler included in the olefin-based resin is a filler and is mainly a powdery inorganic substance, but is not limited thereto. A void refers to a void. “Rigidity” refers to the ability of an object to resist destruction against bending, twisting, etc., and represents the difficulty of deformation. The “specific gravity” refers to the intrinsic specific gravity, for example, about 2.7 for calcium carbonate and about 4.2 for titanium oxide.

In addition, there is provided a stretched reflective tape, wherein the filler has an average particle size of 2.5 to 6.0 μm and the stretched tape has a thickness of 5.0 to 30.0 μm.

  The ratio of the particle size of the filler to the thickness of the stretched tape defines the formation of the protrusion on the surface of the reflective tape and the size of the protrusion. When the particle size of the filler is constant, the protrusion becomes larger as the tape thickness is thinner. Although the thickness of a general stretched tape is 20 to 30 μm, the present invention promotes the formation of protrusions by thinning while maintaining the tape strength, so that the range of the stretched tape thickness is 5.0 to 30.0 μm. . On the other hand, if the filler is too small, voids are unlikely to occur and surface protrusions are difficult to form. On the other hand, when it is too large, uniform dispersion becomes difficult, and film formation cannot be maintained, and a holed (fish eye) phenomenon occurs in an unstretched film. Therefore, the particle size (average particle size) of the filler is set to 2.5 to 6.0 μm. In addition, the ratio of the average particle diameter of the filler with respect to the thickness of an extending | stretching tape is not specifically limited, It sets suitably in each dimension range.

In addition, there is provided a stretched reflective tape characterized in that the blending ratio of the filler to the olefin resin film is 10 to 35% by weight.

  In the conventional filler-containing stretched reflective tape, there was no viewpoint of forming protrusions on the tape surface. Therefore, in consideration of strength, generally, the blending ratio of the filler is set to about 10% by weight, and as a result, no protrusion was formed. Therefore, in the present invention, the blending ratio of the filler is set to 10% by weight or more. On the other hand, when the blending ratio of the filler was 40% by weight or more in the film state, a problem such as the film breaking occurred, so the MAX of the blending ratio of the filler to the olefin resin film was set to 35% by weight. The blending ratio of 10 to 35% by weight with respect to the olefin resin film refers to the weight ratio of the filler to the total of the weight of the olefin resin and the weight of the filler.

In addition, there is provided a stretched reflective tape characterized in that the irradiation intensity of reflected light in a certain wavelength range is ensured based on the absorption spectrum of the filler.

  Based on the absorption spectrum peculiar to the filler contained, the incident light in the wavelength region that reaches the filler is absorbed, and as a result, the reflected light intensity in the wavelength region decreases. A wavelength region in which the reflected light intensity should be ensured can be selected by considering an absorption spectrum unique to the filler in the selection of the filler.

In addition, there is provided a stretched reflective tape characterized by a large standard deviation in the particle size distribution of the filler.

When incident light is reflected by a filler that is a surface protrusion or core, in the case of a filler with a large particle size, the surface protrusion or the surface of the filler that the incident light strikes is relative to the wavelength of the incident light. The surface becomes flat and the ratio of specular reflection increases. On the other hand, in the case of a filler having a small particle size, the ratio of diffuse reflection increases. The average particle size of the filler cannot be made very small due to the formation of the surface protrusion, but if the standard deviation of the particle size is increased, the distribution ratio of the filler having a small particle size increases, and diffuse reflection in the short wavelength region increases. The ratio can be increased.

  In addition, a stretched reflective tape is provided in which the filler is calcium carbonate.

The absorption spectrum of calcium carbonate is dispersed in the ultraviolet and infrared light regions, and a high diffuse reflectance can be ensured in a wide wavelength region centering on the visible light region.

Further, the filler is composed of a plurality of substances, and each substance in the plurality of substances is different in at least one of absorption spectrum, average particle size, or standard deviation in particle size distribution. A stretched reflective tape is provided.

The diffuse reflection ratio can be increased while considering the wavelength region by combining a plurality of fillers having different properties in consideration of the particle size of the filler and the characteristic absorption spectrum.

A stretched reflective tape is provided in which the film has an uneven shape in cross section.

  A thick part can be formed in a part of the cross section of the stretched tape by slitting and stretching the film having an uneven shape in cross section.

A stretched reflective tape is provided in which a reflective film having a multilayer structure in which two of the reflective films are arranged on both sides of an olefin resin film not including the filler is stretched.

Such a stretched reflective tape is composed of one or more central layers not including fillers and voids and a multilayer of both layers including fillers and voids. Usually, a multilayer structure is formed by coextrusion, but is not limited thereto.

There is provided a reflective sheet characterized in that the above stretched reflective tape is knitted.

A reflective sheet is produced by weaving or knitting stretched reflective tape. It is also possible to combine warps and wefts that differ in at least one of the absorption spectrum, average particle size, or standard deviation in particle size distribution, weight percent, and tape thickness.

A reflective sheet is provided in which the stretched reflective tape is used only in part.

In order to maintain the strength of the stretched tape, in addition to the regulation of the average particle diameter of filler, tape thickness, filler weight%, change of the shape and structure of the tape, there is a method to adjust how to use the stretched tape in the reflective sheet. is there. For example, the stretched reflective tape according to the present invention can be used only for warp or weft, and the other yarns can be ordinary reflective tapes. Further, only a part of the warp or the weft, or only a part of the warp and the weft may be the stretched reflective tape according to the present invention, and the other threads may be a normal reflective tape.

A step of mixing an olefin resin and a large number of fillers having a specific gravity greater than that of the olefin resin and high rigidity;
Film-forming the mixed composition into a film;
Stretching the film to create a stretched reflective tape, and
By stretching the film, voids are formed around the filler, and a large number of protrusions having the filler and the void as a core on the surface of the stretched reflective tape as the film is thinned based on the stretching. Part is formed,
A method of manufacturing a stretched reflective tape that reflects light from a light source to the surroundings is provided.

By stretching the film according to the present invention, it is possible to produce a stretched reflective tape in which a large number of protrusions having the filler and the void as a core are formed on the surface of the tape.

According to the present invention, a large number of protrusions are formed on the surface and a large number of fillers are present in the olefin resin. The surface protrusions are the difference in protrusion height based on the difference in filler particle size and distance from the filler surface, asymmetry of the surface protrusion shape due to the presence of voids, and those when multiple fillers are close to each other. It exhibits a complicated shape due to the complexity of the reflected surface protrusion. Therefore, it is possible to improve the ratio of reflecting incident light in the reflection sheet in the field of construction and agriculture according to the present invention, and to prevent high temperature in summer and prevention of heat storage of the reflection sheet. Furthermore, the ratio of the diffusely reflected light in the reflected light can be increased based on the complex protrusion shape on the surface. Also, part of the incident light that has entered the inside is emitted as diffuse reflected light from the tape surface by reflection on the filler surface or reflection through the void, and irradiates the surroundings. The diffuse reflection light refers to the reflection light that excludes the specular reflection light.
As a result, the ratio of the entire diffuse reflection is further increased, and the reflected light can be irradiated almost uniformly on the surroundings without being affected by the incident light angle in the agricultural field or the like. Accordingly, even when sunlight enters only from one direction depending on conditions such as the shape of the building, or even when sunlight enters only for a specific time due to the weather, the reflected light can be uniformly supplied to the surroundings. Furthermore, reflected light can be irradiated also to a short plant and the underside of a plant.

By making the stretched tape as thin as possible, it is possible to promote the generation of protrusions on the tape surface with fillers and voids as cores and the increase in the size of the protrusions. Moreover, by increasing the particle size of the filler as much as possible without causing perforation of the tape, voids are generated more greatly, and the protrusions on the surface of the olefin-based resin tape can be made larger and higher. Therefore, the diffuse reflectance ratio on the tape surface and the diffuse reflectance due to the filler of incident light that has once entered the inside are increased, and the diffuse reflectance as a whole is increased.

  By increasing the weight percentage of the filler in the olefin resin as much as possible, the density of the filler present in the olefin resin is increased. This increases the number of protrusions generated on the tape surface and increases the diffuse reflectance. Furthermore, the increase in filler density increases the possibility that another filler is present inside the filler near the tape surface, and the incident has entered the surface without hitting the surface of the olefin resin and the filler and voids near the surface. There is a high possibility that light is also diffusely reflected by the internal filler. As a result, the overall diffuse reflectance is further increased.

  Utilizing light absorption (absorption spectrum) in a specific wavelength region that the filler has, diffuse reflection light in a wavelength region necessary for surrounding crops and the like can be supplied. If you want to supply diffusely reflected light in the entire visible light region, select a filler that has little or no effect in the visible light region and diffuse it into the ultraviolet light region for the purpose of insect protection. When it is desired to supply reflected light, a filler that has little influence even if it does not have or has an absorption spectrum in the ultraviolet region may be selected. In addition, when it is desired to eliminate the supply of diffuse reflection light in a certain region due to the necessity of the target crop, a filler having an absorption spectrum in that region may be selected.

If the standard deviation of the particle size distribution of the filler is large and the number of fillers having a particle size in the short wavelength region is increased, the diffuse reflectance in the ultraviolet region can be increased. As a result, the ultraviolet light is evenly irradiated to the surroundings, and the insect repellent effect is increased.

By using calcium carbonate as a filler, it has a high diffuse reflectance over a wide range from the ultraviolet region to the infrared region.

By adopting multiple fillers with different standard deviations in absorption spectrum, average particle size, and particle size distribution, it is possible to secure diffuse reflectance in a wide area or keep diffuse reflectance in a certain area at a higher level. it can. It is also possible to reduce the diffuse reflectance of a part of a wide area.

The reflective tape according to the present invention increases the diffuse reflectance by reducing the tape thickness as much as possible. By making such a film into a concavo-convex shape in a cross-sectional view, the reflective tape stretched after the slit has a thick portion and a thin portion in a cross-sectional view. Due to the presence of the thick portion, it is possible to prevent a reduction in the strength of the tape due to stretching. In this case, the protrusions on the surface are mainly generated in the thin portions.

By adopting the multilayer structure, it is possible to prevent the strength of the tape from being reduced by stretching. The central olefin-based resin layer does not include a filler and does not generate voids, and thus is more useful for maintaining the overall strength.

By knitting the stretched reflective tape described above, a reflective sheet with improved diffuse reflectivity can be provided. Since the sheet is woven, it is strong against non-woven fabrics and can withstand long-term use.

By creating the reflective sheet using the stretched reflective tape according to the present invention only on the entire warp or weft or only on a part of the warp or weft, the overall strength can be ensured by the yarn or part free of filler and void. .

By the production method according to the present invention, a stretched reflective tape having excellent light reflectivity and diffuse light reflectivity and high durability can be produced by a simple method.

It is a slope schematic diagram of the extending | stretching reflective tape which concerns on this invention. It is a cross-sectional schematic diagram of the stretched reflective tape according to the present invention. It is a plane schematic diagram of the stretched reflection tape according to the present invention. It is the model which showed the incidence | injection and reflection of sunlight with respect to the extending | stretching reflective tape which concerns on this invention. It is a diffuse reflectance graph in each wavelength range of the extending | stretching reflective tape which concerns on this invention. It is a diffuse reflection and transmittance | permeability graph in each wavelength range of the extending | stretching reflective tape which concerns on this invention.

  A stretched reflective tape for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view of a stretched reflective tape according to the present invention. 1A is a slope view, FIG. 1B is a cross-sectional view with the extending direction as a horizontal axis, and FIG. 1C is a plan view. 1 is a stretched reflective tape according to the present invention, 11 is polyethylene as a material of the stretched reflective tape, 12a is calcium carbonate as a filler, 13 is a void (void), and 14 is a surface protrusion.

  When the unstretched film is stretched, a long void 13 is generated around the calcium carbonate (filler) in the stretching direction. Further, on the surface of the thinned stretched tape, a surface protrusion 14 having an internal calcium carbonate (filler) 12a and a void 13 as a core is formed. Since the surface protrusions 14 overlap with each other depending on the distribution state of the fillers 12a, the surface protrusions 14 have a complicated convex shape as a whole.

  Next, the incident light 2 and the reflected light 3 will be described with reference to FIG. The incident light 2 includes light other than sunlight and includes indirect light. In FIG. 2, incident light from the sun to the stretched reflective tape according to the present invention is 21, 22, and 23. A part of the incident light 21, 22, 23 is reflected on the surface of the stretched reflective tape, but is reflected in a direction different from 31 a, 32 a, 33 a due to the complex-shaped protrusions on the surface, and becomes diffusely reflected light. The incident light 21 and 22 entering the interior without being reflected on the stretched reflecting tape surface is reflected by the filler 12a and emitted from the tape surface (incident surface) again, but the reflecting filler is substantially granular. , 31b, and 32b are reflected in different directions, and become diffusely reflected light. Part of the incident light 23 entering between the fillers is also refracted by the void around the filler, reflected by another filler, and again emitted as diffuse reflected light from the tape surface (incident surface) (33b). Therefore, a high ratio of diffuse reflected light can be obtained by combining the tape surface and the inside.

The implementation of the stretched reflective tape according to the present invention will be described in detail.
In the present invention, examples of the polyolefin resin used for the polyolefin drawn tape include high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, and polypropylene. As polypropylene, a propylene homopolymer, an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, or a mixture thereof can be used.
Among these, high density polyethylene and polypropylene are preferable in consideration of mechanical properties such as strength of stretched tape, extrudability during production, stretchability, etc., and melt flow rate is 0.6 to 1.0 g / in high density polyethylene. Preferred is 10 minutes, 0.8 to 6 g / 10 minutes with polypropylene.

In the composition of the present invention, as the inorganic filler to be mixed with the polyolefin resin, known ones conventionally used in the production of reflective films are used.
Examples include calcium carbonate, calcium sulfate, calcium sulfite, calcium phosphate, magnesium carbonate, hydrated silicic acid, anhydrous silicic acid, soda ash, barium sulfate, talc, titanium oxide, and other inorganic or organic metal salts mainly composed of inorganic substances. Can do. Of these examples, barium sulfate, titanium oxide, calcium carbonate and the like are preferable, and calcium carbonate having a relatively small particle size and a large surface area is particularly preferable.

  In the present invention, the particle size of the inorganic filler, particularly calcium carbonate is 0.1 to 15 μm because it greatly affects the formation and reflection of the resulting thin polyolefin tape, and the average particle size is 2.5 to 6.0 μm. Preferably there is. As described above, when the particle size is small, it is difficult to generate voids, and it is impossible to form micro protrusions on the tape surface. In addition, when the particle size is large or the filler content is high, uniform dispersion is difficult, film formation cannot be maintained, and a hole (fish eye) phenomenon occurs in the unstretched film, making it difficult to stretch and tape formation It becomes.

In the composition of the present invention, various known additives such as a light stabilizer, an antioxidant, an antistatic agent, a crystal nucleating agent, a surfactant, a foaming agent, a flame retardant, and a dispersing agent can be used as necessary. You may mix | blend in the range which does not inhibit an effect.
Moreover, the method to mix the said polyolefin resin and the said inorganic filler is not specifically limited, A well-known method is employable.

Subsequently, the manufacturing method of the polyolefin reflective tape of this invention is demonstrated.
First, as a film forming method, a known method such as a T-die water cooling method, a T die chill roll method, a water cooling method, an air cooling inflation method, or the like can be given. One of the features of the present invention is that the thickness of the film is reduced, and the air-cooled inflation method is preferable from this viewpoint.

When it is necessary to add rigidity and mechanical properties to the woven and knitted cloth, the film forming method can be co-extruded using a multilayer die for the purpose of maintaining the characteristics of the present invention. In that case, it is necessary for the surface layer to have the composition and thickness. Since the inner layer is responsible for reinforcing the cloth, it need not contain fillers and need not be thinned. It is arbitrarily set according to the required reinforcement level.

Further, as another method of adding rigidity and mechanical properties, the film can be formed in an uneven shape (with streaks) in the flow direction (sectional view). In this case, it is necessary to make the concave portion have the composition and thickness. The main part of the convex portion is to reinforce the cloth, and it is not necessary to reduce the thickness, and it is not required to form a large number of protrusions on the surface. The thickness is arbitrarily set according to the required reinforcement level.

Next, the obtained unstretched film is slit to a width corresponding to the fineness after stretching. The slit may be a known method, for example, a leather blade assembled in a slit width, or a rotary cutter (round blade). Next, the slitted unstretched tape is stretched in the flow direction while applying heat at a predetermined magnification to give fineness (tape thickness), width, thickness shape, and mechanical properties suitable for woven and knitted fabrics. Is.

In general, it is known that by stretching an unstretched film, peeling occurs at the interface between the polyolefin resin and the inorganic filler to form voids. However, general stretched films having voids do not have protrusions on the surface, and none have high diffuse reflectance over a wide area. In particular, many diffuse reflectances are low in the ultraviolet region. By stretching and thinning the unstretched film according to the present invention, voids are generated around the filler, and at the same time, an effect is obtained by forming a protruding portion with a filler as a core on the stretched tape surface. is there. The draw ratio is not particularly limited as long as the final thickness can be secured, but it is preferably in the range of 4 to 9 times.

Next, for the purpose of dimensional stability of the woven or knitted fabric formed by knitting, strain generated by stretching is removed by heating. Note that strain removal by heating is not necessarily an essential step in the present invention.
The fineness (thickness) of the stretched tape is not particularly limited, but is 100 to 3000 dtex (hereinafter referred to as dt), preferably 200 to 2000 dt, from the viewpoint of moldability as a woven or knitted fabric.

  Various structures such as plain weave, twill weave, tangle weave and imitation weave are used as the woven structure of the knitted and knitted fabric that is woven and knitted using the above-mentioned stretched tape, and the warp knitted structure is used as the knitted structure. , Weft, etc. are used as appropriate.

Examples and Comparative Examples are shown below, but the present invention is not limited to these Examples.
In addition, the physical property measurement value published in the Example and the comparative example was performed by the method shown below.
1) Unstretched film, stretched tape thickness (μm)
A TECLOCK micrometer SMD-565 was used.
2) Inorganic particle size and distribution SALD-2200 manufactured by Shimadzu Corporation was used.
3) Fixed length machine Asano Machinery Co., Ltd. Measuring scale (10m)
4) Fineness measurement (electronic balance: 10m weight)
ELECTRONIC BALANCE TYPE UX2200H manufactured by Shimadzu Corporation
5) Strength measurement Tensile testing machine manufactured by Asano Machinery Co., Ltd.
6) Diffuse reflectance SolidSpec 3700DUV manufactured by Shimadzu Corporation

  HALS is a composition comprising 76% by weight of high density polyethylene (MI = 0.8 g / 10 min, density = 0.959, melting point = 134 ° C.) and 24% by weight of calcium carbonate having an average particle size of 5 μm. 0.5 parts by weight of the weathering agent was added and mixed using a gravimetric automatic raw material mixing apparatus.

Then, using a 75mmφ air-cooled inflation extruder, a cylinder with a die diameter of 300mmφ, a cylinder temperature of 230 ° C, a die temperature of 220 ° C, a blow-up ratio of 1.0, a frost height of 300mm, and a take-up speed of 20m / min. An unstretched film was formed.

Subsequently, the unstretched film was slit with a razor blade arranged at intervals of 25 mm in the width direction, and stretched at 100 ° C. in the lengthwise direction seven times to obtain a stretched tape having a width of 10 mm, a thickness of 10 μm, and a fineness of 1000 dt. The obtained stretched tape was made into a plain weave cloth having a warp density of 15 / 2.54 cm and a weft density of 15 / 2.54 cm using a shuttle loom (manufactured by Sultech).

Various properties of the obtained stretched tape and cloth were measured by the above method.

In the same manner as in Example 1 except that the composition was composed of 84% by weight of high density polyethylene and 16% by weight of calcium carbonate having an average particle diameter of 5 μm, and various properties of the obtained stretched tape and cloth were measured by the above methods. .

  HALS-based weather resistance with respect to 100 parts by weight of a composition comprising 76% by weight of polypropylene (MI = 1.2 g / 10 min, density = 0.9, melting point = 163 ° C.) and 24% by weight of calcium carbonate having an average particle size of 5 μm 0.5 parts by weight of the agent was added and mixed using a gravimetric automatic raw material mixing apparatus.

Then, using a 75 mmφ air-cooled inflation extruder, a cylinder with a die diameter of 300 mmφ, a cylinder temperature of 240 ° C., a die temperature of 240 ° C., a blow-up ratio of 1.0, a frost height of 300 mm, and a take-up speed of 20 m / min, a 20 μm thick cylinder An unstretched film was formed.

Subsequently, the unstretched film was slit with a razor blade arranged at intervals of 25 mm in the width direction and stretched in the lengthwise direction at 110 ° C. by 7 times to obtain a stretched tape having a width of 10 mm, a thickness of 10 μm, and a fineness of 1000 dt. The obtained stretched tape was made into a plain weave cloth having a warp density of 15 / 2.54 cm and a weft density of 15 / 2.54 cm using a shuttle loom (manufactured by Sultech).

Various properties of the obtained stretched tape and cloth were measured by the above method.

Various properties of the obtained stretched tape and cloth were measured in the same manner as in Example 2 except that the composition was composed of 84% by weight of polypropylene and 16% by weight of calcium carbonate having an average particle diameter of 5 μm.

The measurement results according to Examples 1 to 4 are shown in Table 1. The wavelength / diffuse reflectance in the table represents the diffuse reflectance (%) in the wavelength region (nm).

  In the case of Example 2 based on a composition containing 16% by weight of calcium carbonate having an average particle diameter of 5 μm as a filler, the diffuse reflectance in the ultraviolet region (wavelength 280 to 398 nm) is 74.0%, and the visible region (400 The diffuse reflectance of ~ 798 nm is 76.5%, and the diffuse reflectance of the infrared light region (800-1700 nm) is 74.2%, indicating a wide range of diffuse reflectance from the ultraviolet light region to the infrared light region. Yes.

  In the case of Example 1 based on a composition containing 24% by weight of calcium carbonate having an average particle diameter of 5 μm as a filler, 78.5% in the ultraviolet region, 82.0% in the visible region, and 78 in the infrared region. By increasing the filler density to .9%, the diffuse reflectance is higher over the entire range than in the case of Example 2.

  In order to contrast the diffuse reflectance according to the above-described examples 1 and 2 with known examples, commercially available reflective sheets are shown in Table 2. The wavelength / diffuse reflectance represents the diffuse reflectance (%) in the wavelength region (nm) as in Table 1.

In Examples 3 and 4, the resin material (high density PE) in Examples 1 and 2 is replaced with PP. From the measurement results, the diffuse reflectance of Examples 1 and 2 exceeded that of Examples 3 and 4 by several percent in any wavelength region. Comparison with a commercially available reflection sheet is performed based on Examples 1 and 2.

  Lami prescription is a laminate-type commercially available reflective sheet. Reflects by microvoids. The filler material is unknown. The sheet material is PP, and the tape thickness is assumed to be about 20 μm.

The diffuse reflectance of the Lami prescription is 9.6% in the ultraviolet light region, 79.4% in the visible light region, and 73.2% in the infrared light region. Although it shows a diffuse reflectance higher than that, it is lower than those of Examples 1 and 2. In particular, the diffuse reflectance in the ultraviolet region is extremely low.

  The film is a commercially available reflective sheet obtained by biaxially stretching a PE or PP film in the warp direction and the weft direction. By stretching the film, microvoids are generated, and diffuse reflection is aimed at promoting photosynthesis (visible light center). Is. There are a type containing a filler and a type adding a foaming agent.

  The diffuse reflectance of the film was 14.0% in the ultraviolet light region, 63.6% in the visible light region, and 42.8% in the infrared light region. Well below. In particular, the diffuse reflectance in the ultraviolet region is significantly lower.

  As the aluminum tape, “Venus Metal” manufactured by Koizumi Hemp Co., Ltd. was used. A 50 μm film in which an aluminum foil (6.5 μm) is sandwiched between PE uniaxially stretched films (23 μm) is used as the warp, and the weft uses PE tape.

  The diffuse reflectance of the aluminum tape is 61.7% in the ultraviolet region, 74.1% in the visible region, and 77.4% in the infrared region. However, it is lower than those of Examples 1 and 2 in other cases.

  Aluminum vapor deposition used “Baron Screen B & S” manufactured by Koizumi Hemp Co., Ltd. Two films are bonded together, one film is aluminum deposited on a PE uniaxially stretched film, and the other sheet is black printed on a PE uniaxially stretched film. The laminated film is used as warp after slitting, and PE monofilament is used for weft.

  The diffuse reflectance of aluminum vapor deposition is 2.6% in the ultraviolet light region, 1.5% in the visible light region, and 1.1% in the infrared light region. In the case of aluminum vapor deposition, it is considered that the specular reflectance is high. From the viewpoint of supplying the reflected light uniformly around the object, which is the object of the present invention, aluminum vapor deposition is not suitable.

  As the nonwoven fabric, a reflective sheet “Tyvek (registered trademark)” manufactured by DuPont was used. This is a sheet (nonwoven fabric) in which 0.5 to 10 μm polyethylene ultrafine fibers are bonded by applying high heat.

  The diffuse reflectance of the nonwoven fabric is 82.7% in the ultraviolet region, 91.5% in the visible region, and 85.9% in the infrared region, all of which are extremely high.

  The contrast with the commercially available reflective sheet confirmed the high diffuse reflectance of the stretched reflective sheets of Examples 1 and 2 according to the present invention. Compared with the nonwoven fabric, the diffuse reflectance of the nonwoven fabric exceeded, but the difference is not so large. In addition, the woven and knitted sheet is suitable for severe use because it is more durable than the non-woven fabric.

The measurement results of Comparative Examples 1 and 2 according to the present invention shown in Table 3 are compared with Examples 1 and 2. Similar to Table 1, the wavelength / diffuse reflectance in the table represents the diffuse reflectance (%) in the wavelength region (nm).

  In Comparative Examples 1 and 2, as in Examples 3 and 4, the olefin resin is PP. Therefore, the measurement results are compared with Examples 3 and 4. Comparative Example 2 is based on a material obtained by adding 6 parts by weight of titanium oxide as a filler to 100 parts by weight of the composition of Example 4 (calcium carbonate 16% by weight).

  The diffuse reflectance of Comparative Example 2 is 17.2% in the ultraviolet region, 90.8% in the visible region, and 85.6% in the infrared region. In the visible light region and the infrared light region, the numerical values are extremely high, which is approximately 20% higher than in Example 4. It is a numerical value comparable to the nonwoven fabric of a comparative example. On the other hand, the diffuse reflectance in the ultraviolet region is extremely low.

  By further adding titanium oxide to calcium carbonate, the density of the filler is increased, the protrusions on the surface are increased, and the filler density inside is also increased. Therefore, if other conditions are the same, the diffuse reflectance is considered to be higher. In fact, in the visible light region and the infrared light region, the diffuse reflectance is clearly increased by adding titanium oxide. On the other hand, the diffuse reflectance in the ultraviolet region is rather remarkably lowered (about 50%).

Comparative Example 1 is based on a material obtained by adding 6 parts by weight of titanium oxide as a filler to 100 parts by weight of the composition of Example 3 (calcium carbonate 24% by weight).

  The diffuse reflectance of Comparative Example 1 is 17.4% in the ultraviolet region, 92.6% in the visible region, and 87.9% in the infrared region, which is about 15% higher than Example 3. It exceeds the diffuse reflectance of the nonwoven fabric of the comparative example. That is, it has the highest diffuse reflection light in the visible light region and the infrared light region. On the other hand, the diffuse reflectance in the ultraviolet light region is rather remarkably lowered (about 60%), which is almost the same value as in Comparative Example 1.

  When comparing Comparative Examples 1 and 2, the diffuse reflectance varies depending on the content of calcium carbonate, which is one of the fillers, in the visible light region and the infrared light region, whereas the content of calcium carbonate in the ultraviolet light region is different. Nevertheless, the diffuse reflectance is extremely low, almost the same value. This is considered due to the fact that titanium oxide strongly absorbs the spectrum in the ultraviolet region.

FIG. 3 is a graph of diffuse reflectance for each wavelength when only calcium carbonate is used as a filler and when titanium oxide is added to calcium carbonate. The horizontal axis represents wavelength (nm), and the vertical axis represents diffuse reflectance (%). cc24 (PE) is the diffuse reflectance of the stretched reflective tape based on a composition of 76% by weight of resin (PE) and 24% by weight of calcium carbonate, and cc16 (PE) is 84% by weight of resin (PE) and 16% of calcium carbonate. The diffuse reflectance of the stretched reflective tape based on the composition by weight% is cc24 + to6.0 (PE) is a composition of 76% by weight of resin (PE) and 24% by weight of calcium carbonate, and 6.0% of titanium oxide. The diffuse reflectance of the stretched reflective tape to which parts by weight are added, cc24 + to6.0 (PP) is a composition of 76% by weight of resin (PP) and 24% by weight of calcium carbonate, and 6.0 parts by weight of titanium oxide is further added. The diffuse reflectance of the added stretched reflection tape is shown.
It has been shown that when titanium oxide is added, the diffuse reflectance decreases at a stretch in the ultraviolet region.

  FIG. 4 is a graph of diffuse reflectance and transmittance for each wavelength when only calcium carbonate is used as a filler and when titanium oxide is added to calcium carbonate. The horizontal axis represents wavelength (nm) and the vertical axis represents diffuse reflectance or transmittance (%). cc24 (thru) (PE) is the transmittance of a stretched reflective tape based on a composition of 76% by weight of resin (PE) and 24% by weight of calcium carbonate, and cc24 + to6.0 (thru) is resin (PE) 76 The transmittance of a stretched reflective tape obtained by further adding 6.0 parts by weight of titanium oxide to a composition of wt% and calcium carbonate 24 wt% is shown. In the case where titanium oxide is added, not only the diffuse reflectance is lowered at once in the ultraviolet light region, but also the transmittance is lowered to almost zero. From this, it is considered that titanium oxide absorbed ultraviolet light, and as a result, the diffuse reflectance in the ultraviolet light region was reduced at a stretch.

  It is considered that a high diffuse reflectance can be maintained from the ultraviolet light region to the infrared light region by using another material having low spectral absorption in the ultraviolet light region as a filler. In addition, it is considered effective to employ titanium oxide as a filler when it is desired to eliminate ultraviolet light irradiation. Thus, it is considered that the wavelength region of diffuse reflection can be controlled based on the selection of the filler considering spectral absorption.

  INDUSTRIAL APPLICABILITY The present invention is useful as a reflective sheet in fields including agricultural reflective sheets and has high industrial applicability.

1 Stretched reflective tape 11 Polyethylene (resin)
12 Filler 12a Calcium carbonate 12b Titanium oxide 13 Void 14 Surface protrusion 2 Incident light (sunlight)
21 Incident light 1
22 Incident light 2
23 Incident light 3
3 reflected light 31 diffuse reflected light 31a surface diffuse reflected light 32a related to incident light 1 surface diffuse reflected light 33a related to incident light 2 surface diffuse reflected light 31b related to incident light 3 internal diffuse reflected light 32b related to incident light 1 incident light Internal diffuse reflection light 33b according to 2 Internal diffuse reflection light 4 according to incident light 3 Transmitted light

Claims (12)

A tape that reflects light from a light source to the surroundings,
The reflective tape is a tape obtained by stretching an olefin resin film containing a large number of fillers,
The filler is a substance having a higher specific gravity and higher rigidity than the olefin resin,
Based on the stretching, voids are formed around the filler, and along with the thinning of the film based on the stretching, a large number of protrusions having the filler and the void as cores are formed on the surface of the tape. Stretched reflective tape characterized by 2. The stretched reflective tape according to claim 1, wherein the filler has an average particle size of 2.5 to 6.0 μm, and the stretched tape has a thickness of 5.0 to 30.0 μm. The stretched reflective tape according to claim 1 or 2, wherein a blending ratio of the filler to the olefin resin film is 10 to 35% by weight. The stretched reflective tape according to any one of claims 1 to 3, wherein the irradiation intensity of reflected light in a certain wavelength region is secured based on the absorption spectrum of the filler. The stretched reflective tape according to any one of claims 1 to 4, wherein a standard deviation in a particle size distribution of the filler is large.   The stretched reflective tape according to any one of claims 1 to 5, wherein the filler is calcium carbonate. The filler is composed of a plurality of substances, and each substance in the plurality of substances is different in at least one of an absorption spectrum, an average particle diameter, and a standard deviation in a particle size distribution. The stretched reflective tape according to any one of claims 1 to 6. The stretched reflective tape according to any one of claims 1 to 7, wherein the film has an uneven shape in cross-sectional view. The stretched reflection according to any one of claims 1 to 7, wherein a reflective film having a multilayer structure in which the two reflective films are arranged on both surfaces of an olefin resin film not including the filler is stretched. tape. A reflective sheet comprising the stretched reflective tape according to claim 1 woven and knitted. The reflective sheet according to claim 10, wherein the stretched reflective tape is used only in part. A step of mixing an olefin resin and a large number of fillers having a specific gravity greater than that of the olefin resin and high rigidity;
Film-forming the mixed composition into a film;
Stretching the film to create a stretched reflective tape, and
By stretching the film, voids are formed around the filler, and a large number of protrusions having the filler and the void as a core on the surface of the stretched reflective tape as the film is thinned based on the stretching. Part is formed,
A method for producing a stretched reflective tape that reflects light from a light source to the surroundings.