JP5709423B2 - Resin film - Google Patents

Description

  The present invention relates to a radiation blocking polyolefin resin film.

  One typical agricultural material is an agricultural film used for covering facilities such as houses and tunnels. Conventionally, films made of polyolefin resins such as polyvinyl chloride films and polyethylene and ethylene / vinyl acetate copolymers have been widely used as agricultural films. Among them, a polyolefin resin film that is lightweight and hardly generates toxic gas during incineration is widely used for facility horticulture. The performance required for these agricultural films in order to express good crop growth in greenhouse horticulture includes transparency and radiation shielding properties.

  As a method of imparting radiation shielding properties to a film, a method of kneading an inorganic filler into a film base material is common. As an example of a resin film in which an inorganic filler is kneaded, Patent Document 1 discloses that the blending weight ratio of lithium / aluminum / magnesium and / or zinc composite hydroxide condensed silicate and hydrotalcite compound is 30/70. A polyolefin-based resin multilayer film having a polyolefin-based resin composition layer containing a blend of ~ 70/30 is disclosed.

JP 2001-16995 A

  However, the film as described in Patent Document 1 has a problem that the transparency deteriorates due to moisture absorption when the film is exposed to water for a long time.

  An object of the present invention is to provide a resin film that is not easily deteriorated in transparency even when exposed to water for a long time, that is, excellent in moisture absorption and devitrification resistance, and capable of efficiently blocking radiation. is there.

That is, the present invention provides a first radiation blocking agent that satisfies the following requirement (1) and a second radiation beam that has a chemical composition different from that of the first radiation blocking agent and satisfies the following requirement (2). A resin film comprising a blocking agent and a polyolefin resin and satisfying the following requirement (3) , wherein the content of the first radiation blocking agent is 9.8 to 11.1% by weight (However, the total amount of the resin film is 100% by weight) .
(1) When the amount of moisture absorbed when the radiation blocking agent is stored at a temperature of 23 ° C. and a relative humidity of 50% for 72 hours and then stored at a temperature of 60 ° C. and a relative humidity of 50% for 24 hours is β, β ≦ 5% by weight.
(2) When the radiation transmission index of the radiation blocking agent is α, α ≦ 60.
(3) The ratio of the weight of the first radiation shielding agent contained in the resin film to the weight of the second radiation shielding agent contained in the resin film is in the range of 3: 1 to 6 : 1.

  The resin film of the present invention is a film having an excellent balance between moisture absorption devitrification resistance and radiation shielding properties.

  The resin film of the present invention contains at least two kinds of radiation blocking agents. The radiation blocking agent is a substance having a property of absorbing or reflecting infrared rays having a wavelength of 2 to 25 μm.

  Examples of the radiation blocking agent include an infrared absorber and an infrared reflector. The infrared reflecting agent reflects infrared rays of any wavelength in at least the above wavelength region.

The first radiation blocking agent used in the present invention is a sample stored at a temperature of 23 ° C. and a relative humidity of 50% for 72 hours, and then stored at a temperature of 60 ° C. and a relative humidity of 50% for 24 hours. When the moisture absorption amount of the sample is β wt%, the radiation blocking agent satisfies β ≦ 5 wt%, preferably β ≦ 2 wt%, and more preferably β ≦ 0.5 wt%. Here, the moisture absorption amount is defined by the following equation.
Hygroscopic moisture content β = ((W2−W1) / W2) × 100 (%)
W1: Weight of the sample when the sample of the radiation blocking agent stored for 72 hours at a temperature of 23 ° C. and a relative humidity of 50% starts to be exposed to a temperature of 60 ° C. and a relative humidity of 50%.
W2: Weight of the sample when the sample was further stored for 24 hours at a temperature of 60 ° C. and a relative humidity of 50% from the time when W1 was measured.
Use of such a first radiation blocking agent contributes to improvement of moisture absorption devitrification resistance of the film.

Preferable first radiation blocking agents include hydrotalcite compounds represented by the following formula (I).
M ²⁺ _1-x Al _x (OH) ₂ (A ⁿ⁻ ) _{X / n} · mH ₂ O Formula (I)
Wherein, M ²⁺ is a divalent metal cation, A ^n-is an n-valent anion, x and m satisfies the condition of 0 <x <0.5 and 0 ≦ m <2.

Examples of the divalent metal cation M ²⁺ include Mg ²⁺ , Ca ²⁺ and Zn ²⁺ . n-valent anion A ^n- is not particularly limited, ^{Cl -, Br -, I -} , NO 3 -, ClO 4 -, SO 4 2-, CO 3 2-, HPO 4 3-, HBO 4 3- , PO ₄ ³⁻ , Fe (CN) ₆ ³⁻ , Fe (CN) ₆ ⁴⁻ , CH ₃ COO ⁻ , C ₆ H ₄ (OH) COO ⁻ , (COO) ₂ ²⁻ , terephthalate ion, naphthalene sulfone Anions such as acid ions can be mentioned. Specific examples of the compound represented by the formula (I) include natural hydrotalcite, Stabilace HT-P (manufactured by Sakai Chemical Industry Co., Ltd.), DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.), and the like. Synthetic hydrotalcite. In addition, it is preferable that n in Formula (I) is 1 or more and 4 or less.

The second radiation blocking agent used in the present invention satisfies α ≦ 60, preferably α ≦ 56, more preferably α ≦ 52, where α is the radiation transmission index. By using such a second radiation blocking agent, a film having excellent radiation blocking performance can be obtained. Here, the radiation transmission index of the radiation blocking agent will be described.
First, a tablet composed of KBr and a radiation blocking agent is obtained. At this time, the blending weights of KBr and radiation blocking agent are KBr = 190 mg, radiation blocking agent = 0.3 mg, and the tablet size is diameter = 10 mm and thickness = 1 mm.
Next, for this tablet, an infrared absorption spectrum was measured at a temperature of 296 K by a transmission method in the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m, and the transmittance T (λ) at the wavelength λ. Get the value of%.
On the other hand, the black body radiation spectrum intensity e (λ) at the wavelength λ at 296K is calculated using the following formula (IV) derived from Planck's law.
Blackbody radiation spectrum intensity e (λ) = (A / λ ⁵ ) / {exp (B / (λ × T)) − 1} (formula IV)
However, A = 2πhC ² = 3.74 × 10 ⁻¹⁶ (W · m ² )
B = hC / k = 0.01439 (m · K)
T is absolute temperature (K), λ is wavelength (m)
Where h is the Planck constant, C is the speed of light, k is the Boltzmann constant, A is the first radiation constant, and B is the second radiation constant.
Next, according to (Formula V), the product of the blackbody radiation spectrum intensity e (λ) and the transmittance T (λ) is divided by 100 to obtain the radiation transmission intensity f (λ).
Radiation transmission intensity f (λ) = e (λ) × T (λ) / 100 (Formula V)
The radiation transmission intensity f (λ) is integrated in the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m to obtain the radiation transmission energy F, and the black body radiation spectrum intensity e (λ) is The black body radiation energy E is obtained by integration in the range of 5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m, and a parameter α defined by the formula: α = 100 × F / E is calculated. In the present invention, this parameter α is defined as the radiation transmission index of the radiation blocking agent.

  The second radiation blocking agent may be any that satisfies α ≦ 60, but a compound having a Si—O bond is preferable. The spectrum of infrared rays emitted from the ground shows a peak at a wavelength of about 10 μm, while the Si—O bond has an absorption characteristic at a wavelength of about 10 μm. Therefore, the radiation blocking agent having a Si—O bond can efficiently absorb the radiation.

Examples of such a second radiation blocking agent include composite hydroxides represented by the following formula (II) disclosed in WO97 / 00828.
[(Li ⁺ _(1-x) M ²⁺ _x ) (Al ³⁺ ) ₂ (OH ⁻ ) ₆ ] ₂ (Si _y O _{(2y + 1)} ^{2 −} ) _{(1 + x)} · mH ₂ O (II )
In the formula, M ²⁺ is a divalent metal cation, and m, x, and y satisfy the conditions of 0 ≦ m <5, 0 ≦ x <1, 2 ≦ y ≦ 4. Examples of M ²⁺ include Mg ²⁺ , Ca ²⁺ and Zn ²⁺ .

Preferable examples of the composite hydroxide represented by the above formula (II) include a compound where x = 0 in the formula (II), that is, a composite hydroxide represented by the following formula (III).
[Li ⁺ (Al ³⁺ ) ₂ (OH ⁻ ) ₆ ] ₂ (Si _y O _{(2y + 1)} ² ) · mH ₂ O (III)
In the formula, m and y satisfy the condition of 0 ≦ m <5 and 2 ≦ y ≦ 4. Examples of such composite hydroxides include OPTIMA-SS (manufactured by Toda Kogyo Co., Ltd.).

  From the viewpoint of the balance between the radiation shielding property and moisture absorption devitrification resistance of the resin film, the blending weight ratio of the first radiation shielding agent and the second radiation shielding agent in the resin film of the present invention is the first radiation. Line blocking agent: second radiation blocking agent = 3: 1 to 8: 1, preferably 4: 1 to 6: 1.

  The average particle size of the first radiation blocker and the average particle size of the second radiation blocker are both preferably 5 μm or less, more preferably 0.05 to 3 μm, 0.1 It is especially preferable that it is -1 micrometer.

  In order to improve the dispersibility of the radiation blocking agent in the resin or film, the radiation blocking agent may be subjected to a surface treatment with the dispersant. Dispersants include higher fatty acids such as stearic acid, palmitic acid, lauric acid, metal soaps such as higher fatty acid metal salts (for example, calcium salts, zinc salts, magnesium salts, barium salts, sodium salts), phosphate esters, Examples include silane coupling agents, aluminum coupling agents, zirconium coupling agents, and various waxes. The surface treatment method may be any method as long as the dispersant uniformly adheres to the surface of the radiation blocking agent. For example, the radiation blocking agent is dispersed in a suitable solvent to form a slurry, and the slurry and the dispersion are dispersed. The method of mixing and stirring an agent is mentioned.

The polyolefin resin used in the present invention includes low density polyethylene, high density polyethylene, a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, an ethylene / vinyl acetate copolymer, an ethylene / methyl methacrylate copolymer. Examples thereof include polyethylene resins such as a copolymer of ethylene and a different monomer having ethylene as a main component such as a coalescence. The density of the low density polyethylene is not particularly limited, and for example, a low density polyethylene having a density of 910 to 930 kg / m ³ can be used. In the present invention, the density of the high-density polyethylene is not particularly limited. For example, low-density polyethylene having a density of 941 to 970 kg / m ³ can be used.

  Examples of the α-olefin having 3 to 20 carbon atoms copolymerized with ethylene include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and 1-decene. More preferably, 4-methyl-1-pentene and 1-hexene are mentioned. The α-olefin having 3 to 20 carbon atoms may be a combination of two or more. As such a combination, for example, a combination of 1-butene and 4-methyl-1-pentene, 1-butene and Examples include a combination with 1-hexene, a combination of 1-butene and 1-octene, a combination of 1-butene and 1-decene, and the like. More preferably, the combination of 1-butene and 4-methyl-1-pentene and the combination of 1-butene and 1-hexene are mentioned.

The density of the ethylene / α-olefin copolymer is not particularly limited, and for example, an ethylene / α-olefin copolymer having a density of 870 to 940 kg / m ³ can be used.

  The ethylene / α-olefin copolymer in the present invention is preferably an ethylene / 1-hexene copolymer, an ethylene / 1-butene / 1-hexene copolymer, an ethylene / 1-octene copolymer, an ethylene / 1- Examples include butene / 1-octene copolymers.

Of the copolymers of ethylene and a different monomer, the main component of which is ethylene is an ethylene / vinyl acetate copolymer. The content of vinyl acetate units is preferably 30% by weight or less, and more preferably 20% by weight or less. The density of the ethylene / vinyl acetate copolymer is not particularly limited. For example, an ethylene / vinyl acetate copolymer having a density of 910 to 950 kg / m ³ can be used.

  From the viewpoint of balance between transparency and strength and radiation shielding performance, the total blending amount of the first radiation shielding agent and the second radiation shielding agent in the resin film of the present invention is 100 parts by weight of polyolefin resin. The amount is preferably 5 to 15 parts by weight, more preferably 8 to 12 parts by weight. The blending amount of the polyolefin resin in the resin film of the present invention is not particularly limited, and is preferably 95 to 70% by weight when the entire resin film is 100% by weight.

  The thickness of the resin film of the present invention is preferably 0.01 mm or more from the viewpoint of film strength. Moreover, when using the said resin film as a covering film of an agricultural and horticultural facility, from the viewpoint of covering workability, the thickness of the above resin film is preferably 0.3 mm or less, and a range of 0.03 to 0.25 mm. More preferred is 0.1 to 0.15 mm.

  The resin film of the present invention is not limited to a single layer film, and may be a multilayer film. When the resin film of the present invention is a multilayer film, the layer structure is not particularly limited. For example, 2 types 2 layers, 2 types 3 layers, 3 types 3 layers, 3 types 4 layers, 4 types 4 layers, 4 types Examples of the layer configuration include five layers, five types and five layers.

  In the case of a multilayer film, the distribution state of the first radiation blocking agent and the second radiation blocking agent is not particularly limited. The first radiation shielding agent and the second radiation shielding agent may be contained in the same polyolefin resin layer, or may be contained in separate polyolefin resin layers. Moreover, the multilayer film may have the polyolefin resin layer which does not contain a radiation shielding agent other than the polyolefin resin layer containing a radiation shielding agent.

  The resin film of the present invention is, for example, a resin composition obtained by adding a predetermined amount of radiation blocking agent and, if necessary, various additives to a polyolefin resin, and kneading them with a mixing and kneading machine. It can be manufactured using a product. Film production methods such as inflation molding, extrusion T-die casting molding and calender molding are used for the production of single-layer films, and coextrusion inflation molding, co-extrusion T-dies for the production of multilayer films. Film forming methods such as a casting molding method, a melt coating molding method, an extrusion lamination molding method, and a dry lamination molding method are also used. In the preparation of the resin composition, as a mixing / kneading machine, for example, it is usually used for processing polyolefin-based resins such as a ribbon blender, a super mixer, a Banbury mixer, a single screw extruder, and a twin screw extruder. Can be used. Among these, an inflation molding method capable of efficiently producing a wide resin film is preferable.

  As one preferred example of the resin film of the present invention, from the first layer, the second layer adjacent to the first layer, and the third layer adjacent to the second layer and located on the opposite side of the first layer. A multilayer film, wherein the second layer (intermediate layer) comprises a first radiation blocker, a second radiation blocker and a polyolefin resin, and the first layer and the third layer (outer layer) However, the multilayer film which consists of polyolefin resin each is mentioned. The resin film having such a configuration is excellent in transparency, strength, impact resistance, blocking resistance, moisture absorption devitrification resistance, radiation blocking property, and the like.

  In the three-layer film, the thickness of both outer layers is preferably 10 to 50 μm. The thickness of the intermediate layer is preferably 30 to 150 μm. The thickness of the intermediate layer is preferably larger than the thicknesses of both outer layers, and the thickness of the intermediate layer is preferably 2 to 4 times the thickness of each outer layer.

  The example of preferable embodiment of the resin film of this invention is a film which has the layer of the anti-fogging film which is the resin film of the said this invention, and comprises the one surface. Examples of the antifogging film include a coating film of an inorganic oxide sol and a coating film made of an inorganic oxide and an organic compound. Examples of the inorganic oxide sol include colloidal silica and alumina sol, and examples of the organic compound include polymer resin binders such as acrylic resins, polyester resins, and polyurethane resins, and surfactants. The antifogging coating may be formed on one side of the resin film, or the antifogging coating may be formed on each of both sides of the resin film. The antifogging film may be a single layer film or a multilayer film having two or more layers. The method of laminating the antifogging film on the resin film may be a method by coating, or a method of laminating a previously produced antifogging film on the resin film.

  When using the method by coating, known coating means such as gravure coating and bar coating can be used.

  The resin film of the present invention may contain additives other than the radiation blocking agent as necessary. Examples of the additive include an antioxidant, a light stabilizer, an ultraviolet absorber, an antifoggant, a lubricant, an antiblocking agent, an antistatic agent, and a pigment.

  Examples of the antioxidant include phosphorous compounds containing a trivalent phosphorous atom such as so-called hindered phenol compounds such as 2,6-dialkylphenol derivatives and 2-alkylphenol derivatives, phosphite compounds and phosphonite compounds. An ester compound is mentioned. These antioxidants may be used alone or in combination of two or more. In particular, from the viewpoint of stabilizing the hue, it is preferable to use a hindered phenol compound and a phosphorus ester compound in combination. Moreover, when the weight of each layer is 100%, the antioxidant is preferably contained in each layer in an amount of 0.01 to 1% by weight, and more preferably 0.03 to 0.5% by weight.

  Examples of the light stabilizer include a hindered amine compound having a structure described in JP-A-8-73667, and specific examples thereof include trade names of tinuvin 622-LD, chimasorb 944-LD (hereinafter referred to as Ciba Specialty). Chemicals), Hostabin N30, VP Sanduvor PR-31 (manufactured by Clariant, Inc.), Saiyasorb UV3529, Saiyasorb UV3346 (manufactured by Cytec). Furthermore, a sterically hindered amine ether compound having a structure described in JP-A-11-315067 can be mentioned, and specifically, trade name Tinuvin NOR371 (manufactured by Ciba Specialty Chemicals) can be mentioned. The amount of the light stabilizer contained in each layer is preferably 0.01 to 3% by weight, more preferably 0.05 to 2% by weight, and particularly preferably 0.1 to 1% by weight.

  Examples of UV absorbers include benzophenone UV absorbers, benzotriazole UV absorbers, benzoate UV absorbers, and cyanoacrylate UV absorbers. These can be used alone or in combination of two or more. You may use together. The amount of the ultraviolet absorber contained in each layer is preferably 0.01 to 3% by weight, more preferably 0.03 to 2% by weight, from the viewpoint of weather resistance imparting effect and suppression of bleeding on the film surface.

  Examples of the antifogging agent include fluorine compounds having a perfluoroalkyl group, ω-hydrofluoroalkyl group, etc. (especially fluorine surfactants), and silicone compounds having an alkylsiloxane group (especially silicone surfactants). Etc. Specific examples of the fluorosurfactant include Unidyne DS-403, DS-406, DS-401 (trade name) manufactured by Daikin Industries, Ltd., and Surflon KC-40 (trade name) manufactured by Seimi Chemical Co., Ltd. Examples of the silicone surfactant include SH-3746 (trade name) manufactured by Toray Dow Corning Co., Ltd. These may be used alone or in combination of two or more. The content of the antifogging agent is preferably 0.01 to 3% by weight, more preferably 0.02 to 2% by weight, and particularly preferably 0.05 to 1% by weight.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the test method in an Example and a comparative example is as follows.

(1) Moisture absorption amount of radiation blocking agent Radiation blocking agent stored for 72 hours at 23 ° C and 50% relative humidity is exposed for 24 hours at 60 ° C and 50% relative humidity. Thus, the moisture absorption amount β (%) was calculated.
Moisture absorption amount β = ((weight after exposure−weight before exposure) / weight before exposure) × 100 (%)

(2) Radiation transmission index of radiation blocking agent Tablets comprising KBr and radiation blocking agent were obtained. At this time, the blending weights of KBr and radiation blocking agent were KBr = 190 mg, radiation blocking agent = 0.03 mg, and the tablet size was diameter = 10 mm and thickness = 1 mm.
Using a Fourier transform infrared spectrophotometer (Nicolet 8700FT-IR manufactured by ThermoFisher SCIENTIFIC), the radiation transmission index of the radiation blocking agent was determined by the following method.
In the range of wave numbers 400,000～40,000M ^-1, by a transmission method, the infrared absorption spectrum was measured at a temperature 296 K, a value of the transmittance T ([nu) at the wave number [nu every wavenumber spacing of 200 meters ^-1 Obtained.
Next, using the relationship of λ = 1 / ν (λ: wavelength (m), ν: wave number (m ⁻¹ )), the transmittance at wavelength λ from the value of transmittance T (ν) at wave number ν. A value of T (λ) was obtained.
On the other hand, the black body radiation spectrum intensity e (λ) at the wavelength λ was calculated according to the equation (IV), and the radiation transmission intensity f (λ) at the wavelength λ was obtained according to the equation (V).
Next, the integral of the radiation transmission intensity f (λ) in the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m, and the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m The black body radiation spectrum intensity e (λ) was integrated by the following method. That is, the wavelength region of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m is changed to wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n , λ _{n + 1} (where λ _n <λ _{n + 1} , 1 / lambda divided by _{n -1 / λ n + 1 =} 200), the interval from lambda ₁ to lambda _2, section from lambda ₂ to lambda _3, · · ·, a section from the lambda _n to λ _{n + 1,} ···· Divided into Next, the integral value of each section was calculated by trapezoidal approximation, and the obtained integral values were summed.

(3) Moisture absorption and devitrification resistance of the film About 3 cm × about 5 cm film pieces are immersed in water and stored at 60 ° C. for 4 weeks. It was allowed to air dry for 1.5 hours. The haze of the film piece before dipping in water and the haze of the film piece after natural drying were measured, and ΔHaze = (haze after natural drying) − (haze before dipping in water) was determined. It was used as an index of moisture absorption devitrification. When ΔHaze is positive, the film has been devitrified due to moisture absorption. In this case, the closer the ΔHaze of the film is to 0, the better the film has moisture absorption devitrification resistance. In addition, the measurement of haze was performed using the direct-reading type | mold haze computer (HGM-2DP by Suga Test Instruments Co., Ltd.) based on JISK7105. However, C light defined in JIS Z8113 was used as measurement light.

(4) Radiation shielding property of resin film Using a Fourier transform infrared spectrophotometer (FTIR-8700, manufactured by Shimadzu Corporation), the radiation transmittance of the resin film is determined by the following method, and the resin film This was a measure of radiation blocking properties.

In the range of wave numbers 400,000～40,000M ^-1, by a transmission method, the infrared absorption spectrum was measured at a temperature 296 K, a value of the transmittance T ([nu) at the wave number [nu every wavenumber spacing of 200 meters ^-1 Obtained.
Next, using the relationship of λ = 1 / ν (λ: wavelength (m), ν: wave number (m ⁻¹ )), the transmittance T ( A value of λ) was obtained.
On the other hand, the black body radiation spectrum intensity e (λ) at the wavelength λ was calculated according to the equation (IV), and the radiation transmission intensity f (λ) at the wavelength λ was obtained according to the equation (V).
Next, the radiation transmission intensity f (λ) is integrated in the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m to obtain the radiation transmission energy F, and the black body radiation spectrum intensity e (λ). Was integrated in the wavelength range of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m to obtain black body radiation energy E. The actual integration was performed by the following method. That is, the wavelength region of 2.5 × 10 ^{−6 to} 25 × 10 ⁻⁶ m is changed to wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n , λ _{n + 1} (where λ _n <λ _{n + 1} , 1 / lambda divided by _{n -1 / λ n + 1 =} 200), the interval from lambda ₁ to lambda _2, section from lambda ₂ to lambda _3, · · ·, a section from the lambda _n to λ _{n + 1,} ···· Divided into Next, the integral value of each section was calculated by trapezoidal approximation, and the obtained integral values were summed.
Next, a parameter G defined by G = 100 × F / E was calculated, and this parameter G was defined as a radiation transmittance. The resin film has better radiation blocking properties as the radiation transmittance is smaller.
e (λ) = (A / λ ⁵ ) / {exp (B / (λ × T)) − 1} (Formula IV)
However, A = 2πhC ² = 3.74 × 10 ⁻¹⁶ (W · m ² )
B = hC / k = 0.01439 (m · K)
T is absolute temperature (K), λ is wavelength (m)
Where h is the Planck constant, C is the speed of light, k is the Boltzmann constant, A is the first radiation constant, and B is the second radiation constant.
f (λ) = e (λ) × T (λ) / 100 (formula V)

  The following moisture-absorbing moisture content β and radiation interception index α were measured. The results are shown in Table 1.

Radiation blocking agent (1): Hydrotalcite compound (HT-P; manufactured by Sakai Chemical Industry Co., Ltd.) Radiation blocking agent (2): Lithium / aluminum composite hydroxide (OPTIMA-SS; manufactured by Toda Kogyo Co., Ltd.) )

輻射線遮断剤（１）は本発明における第一の輻射線遮断剤に、輻射線遮断剤（２）は本発明における第二の輻射線遮断剤にそれぞれ該当する。

The radiation blocking agent (1) corresponds to the first radiation blocking agent in the present invention, and the radiation blocking agent (2) corresponds to the second radiation blocking agent in the present invention.

[Example 1]
10. Using a lab plastmill, polyethylene resin (Excellen GMH GH030, melt flow rate 0.5 g / 10 min, density 912 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 86.3% by weight, radiation blocker (1) 1% by weight, radiation blocking agent (2) 1.9% by weight, glycerin fatty acid ester (Sunsulzer S4120, manufactured by Kao Corporation) 0.6% by weight as an antifogging agent, and antioxidant (Irganox 1010); A composition comprising 0.1% by weight of Ciba Specialty Chemicals Co., Ltd. was obtained.
The obtained composition was formed into a film by a press molding method (temperature: 180 ° C., pressure: 100 kg / cm ² ) to obtain a resin film having a thickness of 100 μm. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Example 2]
A resin film was obtained in the same manner as in Example 1 except that the blending amount of the radiation blocking agent (1) was 10.4 wt% and the blending amount of the radiation blocking agent (2) was 2.6 wt%. . Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Example 3]
A resin film was obtained in the same manner as in Example 1 except that the blending amount of the radiation blocking agent (1) was 9.8 wt% and the blending amount of the radiation blocking agent (2) was 3.2 wt%. . Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Example 4]
Using Laboplast mill, polyethylene resin (Excellen FX CX2001, melt flow rate 2.0 g / 10 min, density 898 kg / m ³ , manufactured by Sumitomo Chemical Co., Ltd.) 86.3% by weight, radiation blocker (1) 4% by weight, radiation blocking agent (2) 2.6% by weight, glycerin fatty acid ester (Sunsulzer S4120, manufactured by Kao Corporation) 0.6% by weight as an antifogging agent, and antioxidant (Irganox 1010); A composition comprising 0.1% by weight of Ciba Specialty Chemicals Co., Ltd. was obtained.
The obtained composition was formed into a film by a press molding method (temperature: 180 ° C., pressure: 100 kg / cm ² ) to obtain a resin film having a thickness of 100 μm. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 1]
A resin film was obtained in the same manner as in Example 1, except that the blending amount of the radiation blocking agent (1) was 6.5% by weight and the blending amount of the radiation blocking agent (2) was 6.5% by weight. . Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 2]
A resin film was obtained in the same manner as in Example 1 except that the blending amount of the radiation blocking agent (1) was 3.2 wt% and the blending amount of the radiation blocking agent (2) was 9.8 wt%. . Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 3]
Using Laboplast mill, polyethylene resin (Excellen GMH GH030, melt flow rate 0.5 g / 10 min, density 912 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 85.0 wt%, radiation blocking agent (1) 2% by weight, radiation blocking agent (2) 6.5% by weight, glycerin fatty acid ester (Sunsulzer S4120, manufactured by Kao Corporation) 0.6% by weight as an antifogging agent, and antioxidant (Irganox 1010); A composition comprising 0.1% by weight of Ciba Specialty Chemicals Co., Ltd. was obtained.
The obtained composition was formed into a film by a press molding method (temperature: 180 ° C., pressure: 100 kg / cm ² ) to obtain a resin film having a thickness of 100 μm. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 4]
A resin film was produced in the same manner as in Example 1 except that the blending amount of the radiation blocking agent (1) was 12.3% by weight and the blending amount of the radiation blocking agent (2) was 0.7% by weight. did. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

ａ／ｂ：輻射線遮断剤（１）と輻射線遮断剤（２）の重量比。

a / b: Weight ratio of the radiation blocking agent (1) to the radiation blocking agent (2).

[Example 5]
A 150 μm thick resin film in which the A layer, the B layer, and the C layer were laminated in this order was produced by a coextrusion inflation molding method (processing temperature: 160 ° C.). The weight ratio of the extrusion amounts of the A layer, the B layer, and the C layer was A layer / B layer / C layer = 1/4/1. The composition of each layer was as follows.

The layer A consists of polyethylene resin (Excellen GMH GH051, melt flow rate 0.4 g / 10 min, density 921 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 78.0% by weight, polyethylene resin (Sumikasen E FV203, melt flow rate). 2.0 g / 10 min, density 913 kg / m ³ , manufactured by Sumitomo Chemical Co., Ltd.) and 22.0% by weight.

The B layer is composed of an ethylene / vinyl acetate copolymer (Evatate H2031, melt flow rate 1.5 g / 10 min, density 940 kg / m ³ , manufactured by Sumitomo Chemical Co., Ltd.), 86.3% by weight, radiation blocking agent (1 10.4% by weight, radiation blocking agent (2) 2.6% by weight, glycerin fatty acid ester (Sunsulzer S4120, manufactured by Kao Corporation) 0.6% by weight as an antifogging agent, and antioxidant (IRGA) Nox 1010 (manufactured by Ciba Specialty Chemicals) and a composition comprising 0.1% by weight.

The C layer is made of polyethylene resin (Excellen GMH GH030, melt flow rate 0.5 g / 10 min, density 912 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 40.0% by weight, polyethylene resin (Excellen GMH GH051, melt flow rate). 0.4 g / 10 min, density 921 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd. 35.0% by weight, polyethylene resin (Sumikasen E FV203, melt flow rate 2.0 g / 10 min, density 913 kg / m ³ ; Sumitomo Chemical It was formed with a composition consisting of 25.0% by weight. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 5]
In the same manner as in Example 5, except that the composition of the radiation blocking agent for layer B was 6.5% by weight of the radiation blocking agent (1) and 6.5% by weight of the radiation blocking agent (2). A resin film was prepared. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

[Comparative Example 6]
In the same manner as in Example 1, except that the radiation blocking agent for layer B was blended with 12.3% by weight of the radiation blocking agent (1) and 0.7% by weight of the radiation blocking agent (2). A resin film was prepared. Table 2 shows ΔHaze and radiation transmittance of the obtained film.

ａ／ｂ：輻射線遮断剤（１）と輻射線遮断剤（２）の重量比。

a / b: Weight ratio of the radiation blocking agent (1) to the radiation blocking agent (2).

  The resin film and laminated film according to the present invention can be used as an agricultural film such as a greenhouse covering film.

Claims (3)

A first radiation blocking agent that satisfies the following requirement (1), a second radiation blocking agent that has a chemical composition different from that of the first radiation blocking agent and satisfies the following requirement (2), and a polyolefin And a resin film satisfying the following requirement (3), wherein the second radiation blocking agent is a compound represented by the following formula (II), and the first radiation blocking agent: Content of 9.8 to 11.1% by weight (however, the total amount of the resin film is 100% by weight).
(1) When the amount of moisture absorbed when the radiation blocking agent is stored at a temperature of 23 ° C. and a relative humidity of 50% for 72 hours and then stored at a temperature of 60 ° C. and a relative humidity of 50% for 24 hours is β, β ≦ 5% by weight.
(2) When the radiation transmission index of the radiation blocking agent is α, α ≦ 60.
(3) The ratio of the weight of the first radiation shielding agent contained in the resin film to the weight of the second radiation shielding agent contained in the resin film is in the range of 3: 1 to 6: 1.

[(Li ⁺ _(1-X) M ²⁺ _X ) (Al ³⁺ ) ₂ (OH ⁻ ) ₆ ] ₂ ・ (Si _y O _{(2y + 1)} ²⁻ ) _{(1 + X)} · mH ₂ O formula (II)
In the formula, M ²⁺ is a divalent metal cation, and m, x, and y satisfy the conditions of 0 ≦ m <5, 0 ≦ x <1, 2 ≦ y ≦ 4. The resin film according to claim 1, wherein the first radiation blocking agent is a compound represented by the following formula (I).
_{^{M 2+ 1-x Al x (}} OH) 2 (A n-) X / n · mH 2 O formula (I) wherein, M ²⁺ is a divalent metal cation, A ^n-is the n-valent An anion,
x and m satisfy the conditions of 0 <x <0.5 and 0 ≦ m <2. The second radiation-blocking agent, a resin film of claim 1 wherein the compound satisfying x = 0 in the formula (II).