JP2018014980A - Agricultural polyolefin-based multilayered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural polyolefin film having a large difference between the transparency at room temperature and the transparency at a high temperature of approximately 50°C, good blocking resistance and high transparency at room temperature.SOLUTION: The agricultural polyolefin multilayered film is provided which has at least an outer layer, an intermediate layer and an inner layer, and in which the outer layer contains at least one kind of polyethylene resin selected from a linear low density polyethylene, a low density polyethylene or an ethylene-vinyl acetate copolymer having a vinyl acetate content of 1 to 10 wt.%, the intermediate layer contains an ethylene-vinyl acetate copolymer having a vinyl acetate content of 1 to 20 wt.%, the inner layer contains at least one polyethylene resin selected from a linear low density polyethylene, a low density polyethylene or an ethylene-vinyl acetate copolymer having a vinyl acetate content of 1 to 10 wt.% and amorphous aluminosilicate particles are contained in at least the intermediate layer.SELECTED DRAWING: None

Description

  The present invention relates to an agricultural polyolefin-based multilayer film, and more particularly to an agricultural polyolefin-based multilayer film whose transparency changes due to environmental temperature changes.

  Conventionally, resin compositions whose light transmittance changes reversibly with changes in environmental temperature are known. For example, Patent Document 1 is composed of a linear α-olefin polymer having 14 or more carbon atoms and another α-olefin polymer or a methacrylic acid ester polymer, and the light transmittance as the environmental temperature changes. Disclosed is a resin composition in which reversibly changes.

  Patent Document 2 discloses a resin composition in which the light diffusivity changes reversibly with a change in environmental temperature by blending a resin and particles.

  Patent Document 3 describes a light control sheet in which particles having an average particle size of 3 μm or more and 50 μm or less are mixed with more than 50 parts by weight and 200 parts by weight or less with respect to 100 parts by weight of a thermoplastic resin. . Further, Patent Document 4 discloses that 0.1 parts by weight to 200 parts by weight of particles having an average particle size of 0.1 μm to 50 μm and 0.01 to 20 parts by weight of a heat ray absorbent with respect to 100 parts by weight of the thermoplastic resin. The light control sheet | seat containing is described.

  However, the invention described in Patent Document 1 has a problem that the decrease in light transmittance may not be efficient from the viewpoint of effective use of light. Moreover, in the film of patent documents 2-4, the film in which transparency changes a lot in the temperature change (20-60 degreeC) exposed when using it outdoors is not obtained.

  By the way, in order to improve the marketability and productivity by semi-forcing or suppressing cultivation of agricultural crops, so-called house cultivation and tunnel cultivation in which useful plants are cultivated under the covering with agricultural covering materials are actively performed. Among the coating materials, agricultural polyolefin-based resin films mainly composed of polyolefin-based resins are lighter in density because they are smaller than vinyl chloride resin, and generate little toxic gas even when incinerated. Wide film that does not require adhesive processing for splicing is widely used because it can be provided at low cost, and it has come to be used as a substitute for agricultural bean that has been used in the past. It is coming.

In recent years, the rise in temperature in summer has become a problem due to the influence of global warming, while the importance of summer cultivation is increasing from the viewpoint of improving land use efficiency. When the weather is sunny in the summer, it is necessary to keep the temperature of the house in the temperature range where crops can grow under conditions where the temperature rises to about 50 ° C. In winter, it is necessary to avoid poor growth due to insufficient light quantity or insufficient temperature, and a balance is required. Since conventional scattering agricultural materials have no temperature sensitivity, it was very difficult to balance summer scattering and winter temperature rise, and it could not be said that sufficient performance was provided. .
In addition, a temperature-sensitive film using known crosslinked acrylic beads has not been widely used as an agricultural material because expensive crosslinked acrylic beads are used. Furthermore, the temperature sensitive film using the crosslinked acrylic beads and the ethylene vinyl acetate copolymer having a high vinyl acetate content has problems such as inferior creep resistance and blocking resistance. Therefore, using inorganic fillers that are inexpensive and have high far-infrared absorptivity and can impart high heat retention performance to the film, not only summer scattering but also winter temperature rise, creep resistance, blocking resistance A concrete realization method was required for agricultural materials that can respond to the above.
Thus, there has been a demand for an agricultural film having a temperature-sensitive light-shielding property that has relatively high transparency at a temperature around room temperature and greatly changes in transparency at a high temperature of about 50 ° C. It has not been realized yet.

Japanese Patent No. 2706701 JP 2001-226604 A JP 2009-275133 A JP 2010-241857 A

  An object of the present invention is to provide an agricultural polyolefin-based film having a large difference between transparency at room temperature and transparency at a high temperature of about 50 ° C., good blocking resistance, and high transparency at room temperature. .

  The present inventors have intensively studied to solve this problem. As a result, it is possible to add amorphous aluminosilicate particles to a specific layer in a multilayer film having a specific configuration, thereby improving transparency at room temperature and 50%. Difference in transparency at high temperature of about ℃, good blocking resistance and creep resistance, high transparency at room temperature, consideration for insufficient temperature rise in winter, and other performances required for agricultural films Has found that an excellent polyolefin film for agriculture can be provided, and has completed the present invention.

That is, the present invention
[1] An agricultural polyolefin multilayer film having at least an outer layer, an intermediate layer, and an inner layer, wherein the outer layer is a linear low density polyethylene, a low density polyethylene, or an ethylene vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight. It contains at least one polyethylene-based resin selected from polymers (however, the weight of the ethylene vinyl acetate copolymer is 100% by weight), and the intermediate layer has a vinyl acetate content of 1 to 20% by weight. % Ethylene-vinyl acetate copolymer (A) (however, the weight of the ethylene-vinyl acetate copolymer (A) is 100% by weight), and the inner layer is a linear low-density polyethylene or low-density polyethylene. Or an ethylene vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight (provided that the weight of the ethylene vinyl acetate copolymer is 100% by weight). ) And also contains at least one polyethylene resin selected from, containing amorphous aluminosilicate particles to at least the intermediate layer, the multilayer film.
[2] The agricultural polyolefin-based material according to [1], wherein the intermediate layer contains the amorphous aluminosilicate particles in an amount of 0.1 to 50 parts by weight with respect to 100 parts by weight of the ethylene vinyl acetate copolymer (A). Multilayer film.
[3] The agricultural film according to [1] or [2], wherein the amorphous aluminosilicate particles have a BET specific surface area of 100 (m ² / g) or less.
[4] The agricultural film according to any one of [1] to [3], wherein the amorphous aluminosilicate particles are spherical amorphous aluminosilicates.
[5] An agricultural film containing spherical amorphous aluminosilicate particles having an average particle diameter of 0.01 to 50 μm.
About.

  According to the present invention, the difference in transparency at room temperature and transparency at a high temperature of about 50 ° C. is large, the blocking resistance is good, the transparency at room temperature is high, the temperature rise in winter is considered, and the agricultural film It is possible to provide an agricultural polyolefin-based film having good performances required for the above.

(Embodiment 1)
One embodiment of the present invention is an agricultural polyolefin-based multilayer film having at least an outer layer, an intermediate layer, and an inner layer, wherein the outer layer has a linear low density polyethylene, a low density polyethylene, or a vinyl acetate content of 1 to 10 weights. % Of at least one selected from ethylene vinyl acetate copolymer, and the intermediate layer contains ethylene vinyl acetate copolymer (A) having a vinyl acetate content of 1 to 20% by weight. The inner layer contains at least one selected from linear low density polyethylene, low density polyethylene, or ethylene vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight, and at least an intermediate layer is amorphous. An agricultural polyolefin-based multilayer film containing fine aluminosilicate particles (Embodiment 1).
In the present invention, by including an ethylene vinyl acetate copolymer having a high vinyl acetate content and amorphous aluminosilicate particles in the intermediate layer, there is a difference between transparency at room temperature and transparency at a high temperature of about 50 ° C. It can exhibit increased properties (hereinafter also referred to as “temperature-sensitive light-shielding”), while the outer layer and inner layer are made of linear low density polyethylene, low density polyethylene, or ethylene vinyl acetate copolymer having a low vinyl acetate content. By including at least one selected, stickiness of the film can be suppressed, and as a result, various performances required for agricultural films such as high-temperature light-shielding properties and blocking resistance can be achieved.

  The agricultural polyolefin-based multilayer film of the present invention is composed of at least three layers of an outer layer, an intermediate layer, and an inner layer, but may include more layers, for example, a total of five layers may be formed. (In this case, layers other than the outer layer and the inner layer are called intermediate layers). In the present invention, when the agricultural multilayer film is spread on the house, the layer facing the outside of the house is called an outer layer, and the layer facing the inside of the house is called an inner layer.

  Examples of linear low density polyethylene include ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, and ethylene-octene. A so-called ethylene-α-olefin copolymer may be mentioned. As the linear low density polyethylene, any of those obtained using a Ziegler catalyst, those obtained using a Phillips catalyst, and those obtained using a metallocene catalyst can be used.

  Linear low density polyethylene obtained using a metallocene catalyst is, for example, (Method A) (JP 58-19309, JP 59-95292, JP 60-35005, etc.) and (Method B). (JP-A-6-9724, JP-A-6-136195, JP-A-6-136196, etc.).

  A linear low density polyethylene (hereinafter referred to as “metallocene”) polymerized using a metallocene compound without being restricted by the above-mentioned methods (A) and (B) in that good initial transparency and transparency persistence of the film can be obtained. Linear low density polyethylene ") can also be used.

Low density polyethylene is usually produced by a high pressure radical process and polymerized under high pressure and high temperature conditions. A density of 0.910 to 0.930 g / cm ³ is called low-density polyethylene, but when considering the balance of film processability, flexibility, transparency, strength, etc., it is mainly 0.92 g / cm. Those having a density of around ³ can be preferably used.

  The ethylene vinyl acetate copolymer that can be contained in the outer layer and the inner layer preferably has a vinyl acetate content of 1 to 10% by weight, more preferably 2 to 8% by weight. Here, the vinyl acetate content is a value when the weight of the ethylene vinyl acetate copolymer is 100% by weight. When the vinyl acetate content is in the above range, it is preferable because the film can be prevented from sticking to each other when the film is exposed to a high temperature environment, and the film can be prevented from being fused with a member of a pipe house.

  The outer layer and the inner layer may contain a resin other than linear low density polyethylene, low density polyethylene or ethylene vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight within a range not impairing the effects of the present invention. Good. As such other resins, any resins other than those described above can be used as long as they do not impair the effects of the present invention.

  In the agricultural polyolefin-based multilayer film of the present invention, the types and compositions of the resins contained in the outer layer and the inner layer may be the same or different.

In the agricultural polyolefin-based multilayer film of the present invention, the intermediate layer contains an ethylene vinyl acetate copolymer (A) having a vinyl acetate content of 1 to 20% by weight. Here, the vinyl acetate content is a value when the weight of the ethylene vinyl acetate copolymer (A) is 100% by weight, preferably 1 to 20% by weight, more preferably 2 to 18% by weight. It is.
Although not intended to be bound by theory, in the present invention, at least the intermediate layer contains an ethylene vinyl acetate copolymer as a matrix, and a structure in which amorphous aluminosilicate particles are dispersed in the matrix. The difference in refractive index between the matrix and the particles is slight and transparent at room temperature, but the density of the matrix resin changes at high temperatures, resulting in the refractive index of the matrix resin and amorphous aluminosilicate particles. It is believed that a difference arises which causes the film to become opaque. Here, the greater the vinyl acetate content in the ethylene vinyl acetate copolymer (A), the lower the refractive index at room temperature and the greater the change in the refractive index of the resin when the temperature is raised from room temperature. In this case, by selecting a matrix resin close to the refractive index (about 1.49) of the amorphous aluminosilicate particles at room temperature, good temperature-sensitive light-shielding characteristics can be obtained. When an ethylene vinyl acetate copolymer having a vinyl acetate content of about 10 to 20% by weight is used as a matrix, the refractive index of amorphous aluminosilicate particles is adjusted to the refractive index at room temperature (around 1.5). As a result, good temperature-sensitive characteristics can be imparted. Therefore, by appropriately selecting the refractive index at each temperature of the amorphous aluminosilicate particles and the matrix resin, the design as an agricultural film is facilitated.
On the other hand, when the vinyl acetate content is larger than 20% by weight, the melting point of the ethylene vinyl acetate copolymer is lowered to 80 ° C. or lower, so that the film is easily sticky when exposed to a high temperature environment and the blocking resistance is poor. In addition, it is not preferable because the film is fused with a member of the pipe house after the expansion. Furthermore, after the stretching, the film is liable to be loosened, hit by the wind and hit the aggregate, and problems such as tearing easily occur. Therefore, by making the vinyl acetate content in the range of 1 to 20% by weight, it is possible to balance the effect of lowering transparency at high temperature and the blocking resistance and the effect of preventing film fusion at high temperature. .
Here, as the ethylene vinyl acetate copolymer, an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or less is usually used, but the blocking resistance and creep resistance of the resulting agricultural film are improved. In consideration, an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or more can be used in combination as long as the effects of the present invention are not impaired. In this case, the vinyl acetate content can be 20% by weight or less as a calculated value according to the addition ratio of each ethylene vinyl acetate copolymer. In addition, the vinyl acetate content as the total amount when two or more kinds of ethylene vinyl acetate copolymers are used in combination can be confirmed by analysis by microscopic IR.

  The intermediate layer may contain a resin other than the ethylene-vinyl acetate copolymer (A) as long as the effects of the present invention are not impaired. As such another resin, any resin can be selected as long as the effects of the present invention are not impaired.

The polyolefin multilayer film for agricultural use of the present invention contains amorphous aluminosilicate particles at least in the intermediate layer. By including amorphous aluminosilicate particles in at least the intermediate layer, it has a relatively high transparency at temperatures near room temperature, and the temperature-sensitive light-shielding property that the transparency changes greatly at a high temperature of about 50 ° C. Furthermore, the polyolefin system for agriculture which has high far-infrared absorptivity can be provided.
As the amorphous aluminosilicate particles, the average particle size is preferably 0.01 μm to 50 μm. Among them, the average particle size is average due to the balance of transparency at room temperature, temperature-sensitive light-shielding property at high temperature, and film formability. The particle size is more preferably 0.02 to 25 μm, still more preferably 0.1 to 10 μm. The average particle size can be measured by a commonly used measurement method. For example, the particle is observed with a microscope, the diameter of a circle circumscribing the particle, and the center of the circle to the end of the particle. The method of taking the average of the shortest lengths of the lengths and taking the average value obtained by observing 100 pieces at different locations can be used.
In the present invention, the average particle diameter of the amorphous aluminosilicate particles is in the range of 0.1 to 10 μm, particularly in the range of 0.5 to 2.4 μm, or in the range of 3.5 to 10 μm. preferable. The reason for this is not clear, but an agricultural polyolefin-based multilayer film using amorphous aluminosilicate particles having an average particle diameter in the above range can exhibit better temperature-sensitive light-shielding properties at high temperatures.

The content of the amorphous aluminosilicate particles is preferably 0.1 to 50 parts by weight, more preferably 1 to 40 parts by weight, with respect to 100 parts by weight of the ethylene vinyl acetate copolymer (A) in the intermediate layer. More preferably, it is 3 to 30 parts by weight.
By setting the content of the amorphous aluminosilicate particles in the above range, it is possible to balance the transparency at normal temperature, the temperature-sensitive light-shielding property and the moldability of the film.

  The BET specific surface area of the amorphous aluminosilicate particles is preferably 100 or less, more preferably 50 or less, and still more preferably 20 or less. By setting the BET specific surface area of the amorphous aluminosilicate particles in the above range, it is possible to balance temperature-sensitive light-shielding properties and film formability.

  As the amorphous aluminosilicate particles, amorphous aluminosilicate having a known shape such as a spherical shape or a cubic shape can be used, but the polyolefin multilayer film for agriculture of the present invention is composed of a matrix resin and an amorphous aluminosilicate. By providing a difference in refractive index temperature dependence at the silicate interface, the scattering characteristics due to temperature change. Since it is necessary to ensure transparency on the low temperature side, it is preferable to use a spherical amorphous aluminosilicate having low anisotropy.

As an amorphous aluminosilicate that can be used in the present invention, for example, main constituent elements are silicon (Si), aluminum (Al), oxygen (O), and hydrogen (H), and a large number of Si-O- Mention may be made of hydrated aluminum silicates assembled with Al bonds. Among them, zeolite can be cited as an easily available material. As zeolites, known zeolites such as synthetic zeolites (artificial zeolites), natural zeolites and the like can be used. However, since synthetic zeolites have a relatively regular particle shape, synthetic zeolites, particularly spherical synthetic zeolites. It is more preferable to use These amorphous aluminosilicates have pores, molecular sieves, catalyst carriers, ion exchangers, gas adsorbents, deodorizing materials, dehumidifying and drying materials, water treatment materials, soil conditioners, livestock. Some are used for excrement disposal materials, cat sand, etc. As an amorphous aluminosilicate that can be used in the present invention, the BET specific surface area is 100 (m ² / g) or less, which is not easily accompanied by desorption reaction of adsorbed water even when exposed to a high temperature during resin processing. A certain amorphous aluminosilicate can be preferably used. Such an amorphous aluminosilicate having a small BET specific surface area can be obtained by a known method such as surface treatment. When the BET specific surface area is 100 (m ² / g) or more, although it depends on the storage environment, the presence / absence of pre-drying and the processing method, there is a tendency to cause appearance defects due to foaming. However, even in the case of foaming at the time of molding, it is possible to suppress foaming by devising surface treatment, preliminary drying, processing temperature, and the like.

Amorphous aluminosilicate particles may be used alone or in combination of two or more.
As long as the effects of the present invention are not impaired, organic particles such as inorganic particles made of known inorganic materials, polyester beads, nylon beads, silicon beads, urethane beads, vinylidene chloride beads, acrylic balloons, crosslinked acrylic particles, crosslinked acrylic Resin particles such as styrene copolymer particles, crosslinked styrene particles, melamine resin particles, benzoguanamine resin particles, polyamide resin particles; inorganic-organic hybrid particles can be used in combination. These particles may be solid or hollow (balloon). These particles other than amorphous aluminosilicate particles may be used alone or in combination of two or more.

  As the amorphous aluminosilicate particles that can be used in the present invention, commercially available ones include, for example, Shilton JC-20, JC-30, JC-40, JC-50, JC-70, etc. Also, Mizusawa Chemical Industry Co., Ltd.); HSZ-920NHA (Tosoh Co., Ltd.) and the like can be mentioned. However, the present invention is not limited to these, and it can be appropriately selected depending on the refractive index temperature dependency with the matrix resin. In addition, a material having a large BET specific surface area, such as HSZ-920NHA, needs to be molded in consideration of foaming such as surface treatment, pre-drying, and processing temperature.

  The agricultural polyolefin-based multilayer film of the present invention contains amorphous aluminosilicate particles in at least an intermediate layer. Here, when the polyolefin-based multilayer film for agriculture of the present invention is composed of three or more layers (for example, a five-layer structure), an intermediate layer composed of a plurality of layers (in the case of a total five-layer structure, the intermediate layer is Crosslinked acrylic particles may be contained in any one of the three layers. In addition, amorphous aluminosilicate particles may be contained in the outer layer and / or the inner layer as long as the effects of the present invention are not impaired.

  In the agricultural polyolefin-based multilayer film of the present invention, various additives usually used for agricultural polyolefin-based films can be used in combination. Examples of such additives include anti-fogging agents, anti-fogging agents, weather resistance improvers (hindered amine light stabilizers, ultraviolet absorbers, etc.), weather resistance agents, hindered amine compounds, infrared absorbers, heat retention agents, fillers, Metal organic acid salt, basic organic acid salt and overbased organic acid salt, hydrotalcite compound, epoxy compound, β-diketone compound, polyhydric alcohol, halogen oxyacid salt, sulfur-based, phenol-based and phosphite-based And antioxidants, heat stabilizers, lubricants, antistatic agents, colorants, antiblocking agents, and the like.

  Antifogging agents include polyhydric alcohol partial esters composed of polyhydric alcohols and higher fatty acids, including various known nonionic surfactants, anionic surfactants, cationic surfactants, etc. And silicone surfactants can be suitably used. Specific examples of such surfactants include, for example, nonionic surfactants such as sorbitan palmitate, alkylene oxide adducts of sorbitan palmitate, sorbitan stearate, alkylene oxide addition of sorbitan stearate. , Polyoxyalkylene sorbitan fatty acid ester, sorbitan alkylene oxide adduct and sorbitan monopalmitate (wherein sorbitan stearate and sorbitan palmitate include monoesters, diesters, triesters, and mixtures thereof) ) Sorbitan surfactants, glycerin monopalmitate, glycerin monostearate, glycerin monolaurate, diglycerin monopalmitate, Glycerin surfactants such as serine dipalmitate, glycerin distearate, diglycerin monopalmitate monostearate, triglycerin monostearate, triglycerin distearate or their alkylene oxide adducts and polyethylene glycol mono Polyethylene glycol surfactants such as stearate, polyethylene glycol monopalmitate, polyethylene glycol alkylphenyl ether, and other trimethylolpropane surfactants such as trimethylolpropane monostearate, pentaerythritol monopalmitate, pentaerythritol monostearate Pentaerythritol surfactants such as acrylate, alkylene oxide adducts of alkylphenols; sorbitan / glycerin Esters of condensate and fatty acid, sorbitan / alkylene glycol condensate and fatty acid; diglycerindiolate sodium lauryl sulfate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, dodecylamine hydrochloride, lauramidoethyl laurate Examples thereof include phosphates, triethylcetylammonium iodide, oleylaminodiethylamine hydrochloride, dodecylpyridinium salts and the like and isomers thereof.

  As the antifogging agent, a fluorosurfactant is preferable, and as a specific example of the fluorosurfactant, a part or all of it is replaced with F instead of H bonded to C of the hydrophobic group of a normal surfactant. Substituted surfactants, especially surfactants containing perfluoroalkyl groups or perfluoroalkenyl groups. Such a fluorine-type surfactant can be used individually or in combination of 2 or more types. Examples of the fluorine-containing compound having a perfluoroalkyl group include an anionic fluorine-containing surfactant, a cationic fluorine-containing surfactant, an amphoteric fluorine-containing surfactant, a nonionic fluorine-containing surfactant, and a fluorine-containing oligomer. can give. In the present invention, it is particularly preferable that the fluorosurfactant contains a perfluoroalkylethylene oxide adduct or a perfluoroalkylpropylene oxide adduct.

  As the hindered amine light stabilizer, a hindered amine light weathering agent usually blended for agricultural use can be used. For example, a hindered amine compound (having at least two piperidine ring structures in the molecule and having a molecular weight of 500 or more) Hereinafter, “piperidine ring-containing hindered amine compound”) can also be preferably used.

  Examples of the piperidine ring-containing hindered amine compound include bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2-butyl-2- (3,5-ditert-butyl-4-hydroxybenzyl). ) Malonate, tetra (2,2,6,6-tetramethyl-4-piperidyl) butanetetracarboxylate, tetra (1,2,2,6,6-pentamethyl-4-piperidyl) butanetetracarboxylate, bis ( 2,2,6,6-tetramethyl-4-piperidyl) .di (tridecyl) butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) .di (tridecyl) butanetetra Carboxylate, 3,9-bis [1,1-dimethyl-2- {tris (2,2,6,6-tetramethyl-4-piperidyloxy Rubonyloxy) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-bis [1,1-dimethyl-2- {tris (1,2,2) , 6,6-pentamethyl-4-piperidyloxycarbonyloxy) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,5,8,12-tetrakis [4 , 6-Bis {N- (2,2,6,6-tetramethyl-4-piperidyl) butylamino} -1,3,5-triazin-2-yl] -1,5,8,12-tetraaza Dodecane, 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-piperidinol / dimethyl succinate condensate, 2-tert-octylamino-4,6-dichloro-s-triazine N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine condensate, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) And hexamethylenediamine / dibromoethane condensate.

  In addition, commercially available hindered amine compounds, TINUVIN 770, TINUVIN 780, TINUVIN 144, TINUVIN 622LD, TINUVIN NOR 371, CHIMASSORB 119FL, CHIMASSORB 944 (above, manufactured by Ciba Geigy), Sanol LS-765 (manufactured by Sankyo Co., Ltd., R, MA, K) -68, MARK LA-68, MARK LA-62, MARK LA-67, MARK LA-57, LA-900, LA-81, NO-Alkyl-1 (above, manufactured by ADEKA), UV-3346, UV- 3529, UV-3581, UV-3853 (from Cytec), Hostabin N20, Hostabin N24, Hostabin N30, Hostabin 845, Hostabin NOW, Sandu A PR-31, Nairosutabbu S-EED (or more, manufactured by Clariant Japan KK), UVINUL5050H (or more, BASF Japan Co., Ltd.) and the like can be used. These piperidine ring-containing hindered amine compounds are used alone or in combination of two or more.

  Content of the said hindered amine type compound is 0.001-5 weight part with respect to 100 weight part of resin in each layer of a multilayer film, Preferably it is 0.01-1 weight part. When the content is less than 0.001% by weight, a sufficient effect cannot be obtained, and when the content is more than 5% by weight, the effect is not improved, and the physical properties of the film are deteriorated.

式（１）において、Ｒ１及びＲ２は、それぞれ独立して、水素原子又はメチル基を表し、Ｒ３は水素原子又は炭素数１〜４のアルキル基を表し、好ましくは、Ｒ１及びＲ２はそれぞれメチル基であり、Ｒ３は水素原子である。 Further, the agricultural film of the present invention has a copolymer of ethylene (A) and a cyclic aminovinyl compound (B) represented by the following formula (1) (hereinafter referred to as “ethylene / cyclic aminovinyl compound copolymer”). Can also be added.

In Formula (1), R1 and R2 each independently represent a hydrogen atom or a methyl group, R3 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and preferably R1 and R2 are each a methyl group. And R3 is a hydrogen atom.

  The vinyl compound (B) represented by the formula (1) can be synthesized by a known method, for example, a method described in JP-B-47-8539, JP-A-48-65180, or the like.

  Representative examples of the vinyl compound (B) represented by the formula (1) include 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1,2,2,6,6. -Pentamethylpiperidine, 4-acryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-propyl-2,2,6,6-tetramethylpiperidine, 4-acryloyl Oxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6- Pentamethylpiperidine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl 2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethyl Examples include piperidine.

  As the preferred ethylene / cyclic aminovinyl compound copolymer, the ratio of (B) to the sum of ethylene (A) and cyclic aminovinyl compound (B) is 0.0005 to 0.85 mol%, More preferably, it is 0.001 to 0.55 mol%. That is, the preferred copolymer is one having a high light stability for a low content of the vinyl monomer having a hindered amine group in the side chain (cyclic aminovinyl compound (B)). When the concentration of the cyclic aminovinyl compound (B) is 0.0005 mol%, a sufficient light stabilizing effect is exhibited. On the other hand, when it exceeds 0.85 mol%, it tends to be substantially uneconomical.

  Further, the ethylene / cyclic aminovinyl compound copolymer is such that (B) is not continuous in two or more in the copolymer, and the ratio of being isolated is 83% or more based on the total amount of (B), Preferably it is 90% or more.

  The content of the ethylene / cyclic aminovinyl compound copolymer is preferably 0.5 to 15 parts by weight, particularly preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the resin in each layer of the multilayer film. If this content is less than the above range, the weather resistance is inferior because it is inferior.

  Examples of commercially available ethylene / cyclic aminovinyl copolymers that can be used include XJ100H (manufactured by Nippon Polyethylene Co., Ltd.).

  Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 5,5′-methylenebis (2-hydroxy-4-methoxybenzophenone) and the like. 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-ditert-butylphenyl) benzotriazole, 2- ( 2′-hydroxy-3 ′, 5′-ditert-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzo Triazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- ( 2- (2'-hydroxyphenyl) benzo such as' -hydroxy-3'.5'-dicumylphenyl) benzotriazole, 2,2'-methylenebis (4-tert-octyl-6-benzotriazolyl) phenol Triazoles; phenyl salicylate, resorcinol monobenzoate, 2,4-ditertiarybutylphenyl-3 ′, 5′-ditertiarybutyl-4′-hydroxybenzoate, 2,4-ditertiaryamylphenyl-3 ′, Benzoates such as 5′-ditert-butyl-4′-hydroxybenzoate and hexadecyl-3,5-ditert-butyl-4-hydroxybenzoate; 2-ethyl-2′-ethoxyoxanilide, 2-ethoxy- Substituted oxanilides such as 4′-dodecyl oxanilide; ethyl-α-cyano-β, β-diphenylacrylate, Cyanoacrylates such as ru-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate; 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- [ (Hexyl) oxy] -phenol, triazines such as 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, and the like. can give. These ultraviolet absorbers are used alone or in combination of two or more.

  The ultraviolet absorber is preferably added in an amount of more than 0.001 part by weight and less than 2 parts by weight, and more preferably 0.01 to 1 part by weight with respect to 100 parts by weight of the resin in each layer of the multilayer film. If the content is less than the above range, the effect of improving weather resistance is low, and if it exceeds the above range, there are problems such as a decrease in transparency due to bleeding out.

  By adding an infrared absorber to the agricultural film in the present invention, good heat retention can be imparted. As the infrared absorber, an inorganic compound (inorganic oxide, inorganic hydroxide, hydrotalcite, etc.) containing at least one atom of Mg, Ca, Al, Si and Li that is effective as a heat retaining agent can be used.

Especially, when the hydrotalcite infrared absorber represented by the following formula (2) is used, a film that is inexpensive and has good moldability can be obtained.
_{Mg 4.5 Al 2 (OH) 13} CO 3 · 3.5H 2 O (2)

In particular, when an infrared absorber represented by the following formula (3) is used, a film that is inexpensive and has good moldability can be obtained.
[Al ₂ (Li _(1-x) · M _{(x + y)} ) (OH) _{6 + y} ] ₂ (An ⁻ ) _{2 (1 + x) / n} · mH ₂ O (3) (wherein M is Mg and / or Zn A is an n-valent anion, m is 0 or a positive number, and x and y are in the range of 0 ≦ x ≦ 1, 0 ≦ y ≦ 0.5.)

  The method for obtaining the infrared absorber (heat retention agent) represented by the above formula (3) is not particularly limited, and commercially available products can be used. For example, DHT4A, DHT6A, SYHT-3 (Kyowa Chemical Co., Ltd.) Product), HT-P (manufactured by Sakai Chemical Co., Ltd.), Optima (manufactured by Toda Kogyo Co., Ltd.), Mizukarak (manufactured by Mizusawa Chemical Co., Ltd.), and the like.

  The infrared absorbent (heat retention agent) is inorganic fine particles having infrared absorbing ability, and these can be used alone or in combination of two or more. The inorganic fine particles that can be used are not particularly limited, but inorganic compounds containing at least one atom selected from the components: Si, Al, Mg, and Ca can be used. For example, magnesium oxide, calcium oxide, aluminum oxide, silicon oxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, calcium sulfate, magnesium sulfate, aluminum sulfate, lithium phosphate, calcium phosphate , Magnesium silicate, calcium silicate, aluminum silicate, calcium aluminate, magnesium aluminate, sodium aluminosilicate, potassium aluminosilicate, calcium aluminosilicate, kaolin, clay, talc, mica, zeolite, hydrotalcite compounds and the like. These may be obtained by dehydrating crystal water.

  The inorganic fine particles may be natural products or synthetic products. The inorganic fine particles can be used without being limited by the crystal structure, crystal particle diameter, and the like.

  The content of the inorganic fine particles is preferably more than 0.1 parts by weight and less than 15 parts by weight, and more preferably 1 to 12 parts by weight with respect to 100 parts by weight of the resin in each film layer. If the content is less than the above range, the effect of improving heat retention is low, and if it exceeds the above range, there are problems such as a decrease in transparency.

  Examples of the metal species constituting the organic acid salt, basic organic acid salt and overbased organic acid salt of the metal include Li, Na, K, Ca, Ba, Mg, Sr, Zn, Cd, Sn, Cs, Examples of the organic acid include carboxylic acid, organic phosphoric acid, and phenol.

  Examples of the filler include silica, talc, aluminum hydroxide, hydrotalcite, calcium sulfate, calcium silicate, calcium hydroxide, and hydroxide in order to suppress stickiness of the film or to further increase the heat retention. Magnesium, kaolin clay, mica, alumina, magnesium carbonate, sodium aluminate, conductive zinc oxide, lithium phosphate and the like are used. One type of these fillers may be used, or two or more types may be used in combination.

  Examples of the phenol-based antioxidant include 2,6-ditert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-ditert-butyl-4- Hydroxyphenyl) -propionate, distearyl (3,5-ditert-butyl-4-hydroxybenzyl) phosphonate, thiodiethylene glycol bis [(3,5-ditert-butyl-4-hydroxyphenyl) propionate], 1,6 -Hexamethylene bis [(3,5-ditert-butyl-4-hydroxyphenyl) propionate] and the like.

  Examples of the sulfur-based antioxidant include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl, and distearyl, and β-alkyl mercapto of polyols such as pentaerythritol tetra (β-dodecyl mercaptopropionate). And propionic acid esters.

  Examples of the phosphite-based antioxidant include trisnonylphenyl phosphite, tris (2,4-ditert-butylphenyl) phosphite, tris [2-tert-butyl-4- (3-tert-butyl- 4-hydroxy-5-methylphenylthio) -5-methylphenyl] phosphite.

  Examples of the colorant include phthalocyanine blue, phthalocyanine green, hansa yellow, alizarin lake, titanium oxide, zinc white, ultramarine blue, permanent red, quinacridone, and carbon black.

  The agricultural film of the present invention can contain the above-described components in combination, and can further contain the following optional components as necessary. Optional components include other stabilizers, impact resistance improvers, cross-linking agents, fillers, foaming agents, antistatic agents, nucleating agents, plate-out preventing agents, surface treatment agents, flame retardants, fluorescent agents, anti-glare agents Agents, bactericides, metal deactivators, mold release agents, pigments, processing aids and the like.

  The agricultural film of the present invention is each weighed in a necessary amount for blending various additives, and blending machines such as a ribbon blender, a Banbury mixer, a Henschel mixer, a super mixer, a single or twin screw extruder, a roll, and a kneading machine. Any other known blending machine or mixing machine may be used. In order to form the resin composition thus obtained into a film, a method known per se, for example, a melt extrusion molding method (including a T-die method and an inflation method), calendar processing, roll processing, extrusion molding processing, Blow molding, inflation molding, melt casting, pressure molding, paste processing, powder molding, and the like can be suitably used.

  About the thickness of the polyolefin-type multilayer film for agriculture of this invention, the thing of the range of 0.01-1 mm is preferable at the point of intensity | strength and cost, The thing of 0.05-0.5 mm is more preferable, More preferably, it is 0.00. It is 05-0.2 mm. If the thickness is within this range, an agricultural multilayer film having no problem of strength, molding, and workability can be obtained.

Further, the layer ratio of the outer layer, the intermediate layer, and the inner layer is not particularly limited, but is preferably in the range of 1 / 0.5 / 1 to 1/5/1 in terms of moldability, transparency, and strength. The range of 1/2/1 to 1/4/1 is more preferable. Further, the ratio between the outer layer and the inner layer is not particularly specified, but it is preferable that the ratio is approximately the same because of the curl property of the obtained film.
In addition, various additives such as the above weather resistance improvers (hindered amine light stabilizers, ultraviolet absorbers, etc.), weather resistance agents, infrared absorbers, heat retention agents, etc. may be added to all layers, or some of them. It can also be added to a layer (intermediate layer, or an intermediate layer and an outer layer as an intermediate layer).

  Moreover, an antifogging coating film and other coating films can be formed on the agricultural polyolefin-based multilayer film of the present invention. For example, an antifogging coating film may be formed on the inner surface when an agricultural film is coated on a house, and a dustproof coating film may be formed on the outer surface.

  Examples of the antifogging coating film include a composition mainly composed of a binder resin such as an inorganic colloid sol and / or a thermoplastic resin. Preferably, an antifogging coating film mainly comprising an inorganic colloid substance and a hydrophilic organic compound or an antifogging coating film comprising an inorganic colloid substance and an acrylic resin as main components can be used. Further, the binder resin may not be added, and an inorganic material such as colloidal silica or colloidal alumina may be laminated.

  As the inorganic colloidal sol, inorganic aqueous colloidal particles such as silica, alumina, water-insoluble lithium silicate, iron hydroxide, tin hydroxide, titanium oxide, barium sulfate were dispersed in water or a hydrophilic medium by various methods. And aqueous sols. Among these, silica sol and alumina sol are preferably used, and these may be used alone or in combination.

  As the inorganic colloid sol, it is preferable to select an average particle size in the range of 5 to 100 nm. In this range, two or more colloid sols having different average particle sizes may be used in combination. By setting the average particle size within this range, the coating does not become white and devitrified, and the stability of the inorganic colloidal sol is good.

  The amount of the inorganic colloidal sol is preferably 0.2 to 5 and preferably 0.5 to 4 in terms of the weight ratio as the solid content with respect to the total solid weight of the binder resin composition. That is, when the blending amount is too small, a sufficient antifogging effect may not be exhibited. On the other hand, when the blending amount is too large, the antifogging effect is not easily improved in proportion to the blending amount. The film formed later becomes cloudy and causes a phenomenon that the light transmittance of the film is lowered, and the film may be coarse and brittle, which is not preferable.

  Examples of the binder resin include acrylic resins, epoxy resins, urethane resins, and polyester resins. When the base film is a polyolefin film, it is particularly preferable to use an acrylic resin and / or a urethane resin from the viewpoint of compatibility with the polyolefin film, and more preferably (a) a hydrophilic acrylic heavy film described later. Those made of coalescence, (c) those made of a hydrophobic acrylic resin, and (e) those made of a hydrophobic acrylic resin and a polyurethane emulsion have their respective characteristics and are preferable.

  Examples of the acrylic resin include (a) one made of a hydrophilic acrylic polymer, (b) one made of a block copolymer containing a hydrophobic molecular chain block and a hydrophilic molecular chain block in one molecule, (c ) What consists of hydrophobic acrylic resin is mentioned. When the base film is a polyolefin-based film, (a) is particularly excellent in compatibility with the base film in terms of early antifogging and wetting, while (c) is preferable with the base film. It is excellent in compatibility.

  As the hydrophilic acrylic polymer (a), a hydroxyl group-containing vinyl monomer component is a main component (preferably 60 wt% to 99.9 wt%, more preferably 65 wt% to 95 wt%), acid Examples thereof include a copolymer containing 0.1 to 30% by weight of a group-containing vinyl monomer component, a partially neutralized product thereof, or a completely neutralized product thereof. Examples of the hydroxyl group-containing vinyl monomer component include hydroxyalkyl (meth) acrylates, such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- Examples thereof include, but are not limited to, hydroxypropyl (meth) acrylate. These may be homopolymers, or may be copolymers of these hydroxyalkyl (meth) acrylates as main components and other monomers that can be copolymerized therewith.

  Examples of the acid group-containing monomer copolymerizable with these hydroxyalkyl (meth) acrylates include carboxylic acids, sulfonic acids and phosphonic acids, and (meth) acrylic acid belonging to carboxylic acids is particularly preferred.

  Examples of other copolymer components include styrene, vinyl terene, vinyl chloride, vinylidene chloride, vinyl oxide, (meth) acrylic acid esters, N, N-dimethylaminoethyl (meth) acrylamide, vinyl pyridine, and the like.

  As the hydrophobic acrylic resin (c), at least a total of 60% by weight of a monomer comprising an alkyl ester of acrylic acid or methacrylic acid, or a single unit of an alkyl ester of acrylic acid or methacrylic acid and an alkenylbenzene. A monomer mixture and 0 to 40% by weight of a copolymerizable α, β-ethylenically unsaturated monomer are obtained by emulsion polymerization in an aqueous medium, for example, in the presence of an emulsifier, under normal polymerization conditions. And water dispersible polymers or copolymers.

  Examples of alkyl esters of acrylic acid or methacrylic acid used in the production of hydrophobic acrylic resins include acrylic acid methyl ester, acrylic acid ethyl ester, acrylic acid-n-propyl ester, acrylic acid isopropyl ester, acrylic acid-n- A butyl ester etc. are mentioned, Generally, a C1-C20 acrylic acid alkyl ester and / or a C1-C20 methacrylic acid alkyl ester of an alkyl group are used. Examples of alkenylbenzenes include styrene, α-methylstyrene, vinyltoluene and the like.

  Examples of α, β-ethylenically unsaturated monomers used to obtain hydrophobic acrylic resins include α, β such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid. -Ethylenically unsaturated carboxylic acids; α, β-ethylenically unsaturated sulfonic acids such as ethylene sulfonic acid; 2-acrylamido-2-methylpropanoic acid; α, β-ethylenically unsaturated phosphonic acids; acrylic acid or methacrylic acid Hydroxyl group-containing vinyl monomers such as hydroxyethyl; acrylonitriles; acrylic amides; glycidyl esters of acrylic acid or methacrylic acid, and the like. These monomers may be used alone or in combination of two or more, and are preferably used in the range of 0 to 40% by weight. If the amount used is too large, the antifogging performance may be lowered, which is not preferable.

  The acrylic resin is a known emulsifier, for example, an anionic surfactant, a cationic surfactant, or a nonionic surfactant, in the presence of one or more kinds in an aqueous medium. It can be obtained by a method of emulsion polymerization, a method of polymerization using a reactive emulsifier, a method of polymerizing based on an oligo soap theory without containing an emulsifier.

  Examples of the polymerization initiator preferably used for the production of the acrylic resin include persulfates such as ammonium persulfate and potassium persulfate. These can be used in the range of 0.1 to 10% by weight based on the total amount of monomers charged.

  It is particularly preferable to use a hydrophobic acrylic resin having a glass transition temperature of 35 to 80 ° C. If the glass transition temperature is too low, the inorganic colloidal particles are agglomerated several times and tend to be in a non-uniform dispersion state. If it is too high, it is difficult to obtain a transparent uniform coating.

  The hydrophobic acrylic resin is preferably used as an aqueous emulsion. An aqueous emulsion obtained by polymerization of each monomer in an aqueous medium may be used as it is, or may be diluted by adding a liquid dispersion medium to this, and also produced by the above polymerization. A polymer may be collected separately and re-dispersed in a liquid dispersion medium to form an aqueous emulsion.

  On the other hand, examples of the (d) urethane-based resin include polyether-based, polyester-based, and polycarbonate-based anionic polyurethane aqueous compositions and emulsions. When the base film is a polyolefin-based film, a polycarbonate-based anionic polyurethane emulsion is preferable from the viewpoint of adhesion of the anti-fogging coating film to the base film, water resistance and scratch resistance, and further anti-fogging coating. A polycarbonate-based anionic polyurethane emulsion containing a silanol group is more preferable from the viewpoints of improvement in water resistance and scratch resistance of the film, time until the antifogging property is developed, and antifogging durability. These may be used alone or in combination of two or more.

  A polycarbonate-based anionic polyurethane emulsion containing a silanol group comprises a polyurethane resin containing at least one silanol group in the molecule and a strongly basic tertiary amine as a curing catalyst. Refers to a colloidal dispersion system (emulsion) in which the silanol group-containing polyurethane resin and the strongly basic tertiary amine are dissolved in the aqueous phase, or a colloidal dispersion system in which fine particles are dispersed.

  It is preferable that the amount of the polyurethane aqueous composition is 0.01 or more and 2 or less, more preferably 0.01 or more and 1 or less with respect to the hydrophobic acrylic resin in terms of solid content by weight. When it is less than 0.01, it is difficult to improve the scratch resistance, and it takes a long time until the antifogging property is exhibited, and it is difficult to exhibit a sufficient antifogging effect. In addition, when it is too much, not only the scratch resistance is difficult to improve in proportion to the blending amount, but the coating film formed after coating tends to become cloudy and lower the light transmittance, which is also disadvantageous in terms of cost. It is not preferable.

  When preparing an antifogging agent composition for forming an antifogging coating film, an anionic surfactant, a cationic surfactant, a nonionic surfactant, a polymer surfactant, etc. An activator can be added. The following can be used as such a surfactant.

  Anionic surfactants include fatty acid salts such as sodium oleate and potassium oleate; higher alcohol sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; alkylbenzene sulfones such as sodium dodecylbenzenesulfonate and sodium alkylnaphthalenesulfonate Acid salt and alkyl naphthalene sulfonate salt; naphthalene sulfonic acid formalin condensate; dialkyl sulfosuccinate salt; dialkyl phosphate salt; polyoxyethylene sulfate salt such as sodium polyoxyethylene alkyl ether sulfate and sodium polyoxyethylene alkylphenyl ether sulfate Can be mentioned.

  Cationic surfactants include: ethanolamines; laurylamine acetate, triethanolamine monostearate formate; amine salts such as stearamide ethyl diethylamine acetate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, dilauryldimethyl And quaternary ammonium salts such as ammonium chloride, distearyldimethylammonium chloride, lauryldimethylbenzylammonium chloride, and the like.

  Nonionic surfactants include polyoxyethylene higher alcohol ethers such as polyoxyethylene lauryl alcohol, polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; polyoxyethylene such as polyoxyethylene octylphenol and polyoxyethylene nonylphenol. Alkylaryl ethers; polyoxyethylene acyl esters such as polyethylene glycol monostearate; polypropylene glycol ethylene oxide adducts; sorbitan fatty acid esters such as sorbitan monostearate, sorbitan monopalmitate, sorbitan monobenzoate; diglycerin monopalmi Diglycerol fatty acid esters such as tate and diglycerol monostearate; glycerol monostearate Glycerin fatty acid esters such as pentaerythritol monostearate, etc .; dipentaerythritol fatty acid esters such as dipentaerythritol monopalmitate; sorbitan monopalmitate half adipate, diglycerin monostearate half Sorbitan such as glutamate and diglycerin fatty acid / dibasic acid esters; or condensates thereof with alkylene oxide such as ethylene oxide and propylene on oxide such as polyoxyethylene sorbitan monolaurate and polyoxypropylene sorbitan monostearate Etc .; Polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearamide, etc. Carboxymethyl ethylene alkyl amine fatty acid amides; sugar esters.

  Examples of the polymer surfactant include polyacrylate, polymethacrylate, and cellulose ethers.

  The addition of the surfactant can easily and quickly disperse the binder resin and the inorganic colloid sol, and when used in combination with the inorganic colloid sol, imparts hydrophilicity to the surface of the hydrophobic polyolefin resin film. Fulfills the function. The addition amount of the surfactant is preferably selected in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the solid content of the resin. If the amount of the surfactant added is too small, it takes time to sufficiently disperse the resin and the inorganic colloid sol, and the antifogging effect in combination with the inorganic colloid sol cannot be sufficiently exhibited. If the amount added is too large, the transparency of the coating will decrease due to the bleed-out phenomenon on the coating surface formed after coating, and if it is noticeable, it may cause deterioration of the blocking resistance of the coating or decrease the water resistance of the coating. .

  A cross-linking agent can be added when preparing an antifogging agent composition for forming an antifogging coating film. A crosslinking agent has an effect which bridge | crosslinks acrylic resin especially and improves the water resistance of a coating film. Examples of the crosslinking agent include phenol resins, amino resins, amine compounds, aziridine compounds, azo compounds, isocyanate compounds, epoxy compounds, silane compounds, etc., but particularly amine compounds and aziridine compounds. Epoxy compounds can be preferably used.

  A liquid dispersion medium can be mix | blended with the anti-fogging agent composition used for this invention as needed. Such a liquid dispersion medium includes a hydrophilic or water-miscible solvent containing water, water; monohydric alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin. Examples: cyclic alcohols such as benzyl alcohol; cellosolve acetates; ketones and the like. These liquid dispersion media may be used alone or in combination.

  If necessary, the antifogging agent composition can be mixed with conventional additives such as an antifoaming agent, a plasticizer, a film forming aid, a thickening agent, a pigment, and a pigment dispersant. Further, as a binder component other than the acrylic resin, for example, a polyether-based, polycarbonate-based, or polyester-based water-dispersible urethane resin may be mixed.

  In order to form an antifogging coating film on the surface of the agricultural polyolefin-based multilayer film of the present invention, generally a solution or a dispersion of the antifogging composition is respectively applied to a doctor blade coating method, a roll coating method, a dip coating method, a spray. A known coating method such as a coating method, rod coating method, bar coating method, knife coating method, brush coating method, etc. may be employed and dried after coating. As a drying method after coating, either a natural drying method or a forced drying method may be employed. When the forced drying method is employed, the drying method is usually 50 to 250 ° C., preferably 70 to 200 ° C. Good. For heating and drying, an appropriate method such as a hot air drying method, an infrared drying method, a far infrared drying method, and an ultraviolet curing method may be employed, and it is advantageous to adopt the hot air drying method in consideration of the drying speed and stability. is there.

  The thickness of the anti-fogging coating film may be selected based on 1/10 or less of an agricultural polyolefin-based multilayer film (hereinafter also referred to as “base film”), but is not necessarily limited to this range. If the thickness of the coating film is larger than 1/10 of the base film, there is a difference in flexibility between the base film and the coating film, so that a phenomenon such as peeling of the coating film from the base film is likely to occur. Moreover, the phenomenon that a crack occurs in the coating film to reduce the strength of the base film occurs, which is not preferable.

  Moreover, when the adhesiveness of the base film and the coating film derived from an antifogging agent composition is not enough, you may surface-treat to a base film. Examples of the surface treatment method include corona discharge treatment, sputter etching treatment, sodium treatment, and sandblast treatment. In the corona discharge treatment method, discharge is performed between a needle-like or knife-edge electrode and a counter electrode, and a sample is placed between the electrodes, and the film surface contains oxygen such as aldehyde, acid, alcohol peroxide, ketone, ether, etc. This is a process for generating a functional group. In the sputter etching process, a sample is placed between electrodes that are performing low-pressure glow discharge, and a large number of fine protrusions are formed on the film by the impact of positive ions generated by the glow discharge. In the sandblasting process, fine sand is sprayed on the film surface to form a large number of fine irregularities on the surface. Among these surface treatments, corona discharge treatment is preferable from the viewpoints of adhesion to the coating layer, workability, safety, cost, and the like.

(Embodiment 2)
Another embodiment of the present invention is an agricultural film containing spherical amorphous aluminosilicate particles having an average particle size of 0.01 to 50 μm (Embodiment 2).
In the agricultural film of Embodiment 2, it is important to contain spherical amorphous aluminosilicate particles having an average particle diameter in the range of 0.01 to 50 μm, thereby improving transparency at room temperature and high temperature. Therefore, it is possible to provide an agricultural film having a high far-infrared absorptivity.
In the agricultural film of Embodiment 2, the average particle size of the spherical amorphous aluminosilicate particles is more preferably 0 because of the balance between transparency at room temperature, temperature-sensitive light-shielding property at high temperature, and film formability. 0.02 to 25 μm, more preferably 0.1 to 10 μm.
The average particle diameter of the spherical amorphous aluminosilicate particles is particularly preferably in the range of 0.5 to 2.4 μm, or in the range of 3.5 to 10 μm, in the range of 0.1 to 10 μm. Although the reason is not clear, an agricultural film using spherical amorphous aluminosilicate particles having an average particle diameter in the above range can exhibit better temperature-sensitive light-shielding properties at high temperatures.

  As the base resin of the agricultural film of Embodiment 2, polyolefin resin, vinyl chloride resin, acrylic resin, fluorine resin, polyester resin, and the like can be used.

  The vinyl chloride resin refers to a copolymer in which vinyl chloride is the main component in addition to polyvinyl chloride. Examples of the monomer compound that can be copolymerized with vinyl chloride include vinylidene chloride, ethylene, propylene, acrylonitrile, maleic acid, itaconic acid, acrylic acid, methacrylic acid, and vinyl acetate. These vinyl chloride resins may be produced by any of the conventionally known production methods such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization.

  Moreover, as said vinyl chloride-type resin, although an average degree of polymerization is 1000 or more and 2500 or less, Preferably 1100 or more and 2000 or less can be used, However, You may mix 2 types using the thing of different average polymerization degree. As a mixing method, a method of mixing two kinds of resins at the time of film formation processing is generally used. However, two kinds of resins having apparently different average degrees of polymerization can be obtained by controlling polymerization conditions at the time of polymerization of vinyl chloride resin. It may be a mixed method.

  In order to impart flexibility to the vinyl chloride resin film, 30 to 60 parts by weight, preferably 40 to 55 parts by weight of a plasticizer is blended with respect to 100 parts by weight of the resin. If it is less than 30 parts by weight, sufficient low-temperature physical properties cannot be obtained because of low flexibility at low temperatures. On the other hand, if it exceeds 60 parts by weight, the handleability (stickiness, etc.) at room temperature deteriorates and the workability at the time of film formation decreases, which is not preferable.

  Examples of the plasticizer that can be used include phthalic acid derivatives such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, and diisodecyl phthalate; isophthalic acid derivatives such as dioctyl phthalate; di-n-butyl adipate Adipic acid derivatives such as dioctyl adipate; maleic acid derivatives such as di-n-butyl malate; citric acid derivatives such as tri-n-butyl citrate; itaconic acid derivatives such as monobutyl itaconate; oleic acid such as butyl oleate Derivatives; ricinoleic acid derivatives such as glycerin monoricinoleate; epoxidized large oil, epoxy resin plasticizer, and the like. Moreover, in order to give a softness | flexibility to a resin film, it is not restricted to the above-mentioned plasticizer, For example, a thermoplastic polyurethane resin, a polyvinyl acetate, etc. can also be used.

  Moreover, what blended polyvinyl chloride and chlorinated polyethylene can also be used as a vinyl chloride resin. As the chlorinated polyethylene, the raw material polyethylene is ethylene homopolymerization, or ethylene and 30% by weight or less (preferably 20% by weight or less) and 12 or less carbon atoms (preferably 3 to 9). Those obtained by copolymerizing these α-olefins are preferred.

  Specific examples of the α-olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and the like. As polyolefin used as a raw material, what homopolymerized ethylene especially is preferable. As the chlorinated polyethylene, a method in which polyethylene powder or particles are chlorinated in an aqueous suspension or polyethylene dissolved in an organic solvent is chlorinated.

  The amount of chlorinated polyethylene added to the vinyl chloride resin is usually 0.5 to 20 parts by weight, preferably 0.5 to 10 parts by weight. The melt index of chlorinated polyethylene can be appropriately selected within the range of 0.5 to 150 g / 10 minutes.

  Examples of polyolefin resins include α-olefin homopolymers, copolymers of different monomers mainly containing α-olefins, polyunsaturated compounds such as α-olefins and conjugated dienes or nonconjugated dienes, Examples include copolymers with acrylic acid, methacrylic acid, vinyl acetate, and the like, such as high density, low density or linear low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene. Examples include -4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer. Among these, low density polyethylene having a density of 0.910 to 0.935, an ethylene-α-olefin copolymer, and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by weight or less have transparency and weather resistance. It is preferable as an agricultural film from the viewpoint of properties and price. In the present invention, an ethylene-α-olefin copolymer resin obtained by copolymerization with a metallocene catalyst can be used as at least one component of the polyolefin resin.

  This is usually referred to as metallocene polyethylene, and is a copolymer of ethylene and an α-olefin such as butene-1, hexene-1, 4-methylpentene-1, octene. (Method A) (JP 58-19309, JP 59-95292, JP 60-35005, etc.) and (B) (JP 6-9724, JP 6-136195, No. 6-136196).

  A polyolefin resin polymerized by using a metallocene compound, that is, a metallocene polyethylene, is not limited to the above methods (A) and (B) in that good initial transparency and transparency persistence of the film can be obtained. Can be used.

  Polyethylene resins including these metallocene polyethylenes are classified based on temperature rising elution fractionation (TREF), MFR, density, molecular weight distribution, and other various physical properties. Measurement of elution curve by temperature rising elution fractionation (TREF) is described in “Journal of Applied Polymer Science. Vol 126, 4, 217-4, 231 (1981)”, “Polymer Discussion 0 Proceedings 2P1C”. This is carried out based on the principle described in the literature such as “Showa 63”.

The ethylene-α-olefin copolymer used as at least one component of the polyolefin resin of the present invention has an MFR measured by JIS-K7210 of 0.01 to 10 g / 10 min, preferably 0.1 to 5 g / A value of 10 minutes is shown. If the MFR is larger than this range, the film meanders during molding and is not stable. On the other hand, if the MFR is too smaller than this range, the resin pressure at the time of molding increases and a load is applied to the molding machine. Therefore, the increase in pressure must be suppressed by reducing the production amount, which is not practical. The ethylene-α-olefin copolymer used as at least one component of the polyolefin-based resin of the present invention has a density measured by JIS-K7112 of 0.880 to 0.930 g / cm ³ , preferably 0.8. A value of 880 to 0.920 g / cm ³ is shown. When the density is larger than this range, the transparency is deteriorated. On the other hand, if the density is smaller than this range, blocking occurs due to stickiness of the film surface, resulting in poor practicality. The ethylene-α-olefin copolymer used as at least one component of the polyolefin resin of the present invention has a molecular weight distribution (weight average molecular weight / number average molecular weight) determined by gel permeation chromatography (GPC). The value is 1.5 to 3.5, preferably 1.5 to 3.0. When the molecular weight distribution is larger than this range, the mechanical strength is lowered, which is not preferable. If the molecular weight distribution is smaller than this range, the film meanders during molding and is not stable.

  As the ethylene-vinyl acetate copolymer resin, those having a vinyl acetate content in the range of usually 10 to 25% by weight, preferably 12 to 20% by weight, can be used. If the vinyl acetate content is less than this range, the resulting film will be hard and will tend to wrinkle and sag when stretched in a house, which will have a negative effect on anti-fogging properties. If it is larger than the range, the melting point of the resin is low, so that the film loosens at high temperatures in summer during house extension, and is easily broken by wind and flapping with the house structure.

  As the spherical amorphous aluminosilicate that can be used in the present invention, spherical zeolite is preferable. As zeolite, synthetic zeolite (artificial zeolite) or natural zeolite can be used. Since synthetic zeolite has a relatively regular particle shape, it is preferable to use spherical synthetic zeolite.

As the spherical amorphous aluminosilicate particles, one kind or two or more kinds having different particle diameters may be used in combination.
As long as the effects of the present invention are not impaired, organic particles such as inorganic particles made of known inorganic substances, polyester beads, nylon beads, silicon beads, urethane beads, vinylidene chloride beads, acrylic balloons, crosslinked acrylic particles, crosslinked styrene particles , Resin particles such as melamine resin particles, benzoguanamine resin particles, polyamide resin particles; and inorganic-organic hybrid particles. These particles may be solid or hollow (balloon). These particles other than amorphous aluminosilicate particles may be used alone or in combination of two or more.

The content of the spherical amorphous aluminosilicate particles is preferably 0.1 to 50 parts by weight, more preferably 1 to 40 parts by weight, and still more preferably 3 to 30 parts by weight with respect to 100 parts by weight of the base resin. Part.
By setting the content of the amorphous aluminosilicate particles in the above range, it is possible to balance the transparency at normal temperature, the temperature-sensitive light-shielding property and the moldability of the film.

In the agricultural film of Embodiment 2, the same additives as described for the agricultural polyolefin-based multilayer film of Embodiment 1 (for example, antifogging agent, antifogging agent, weather resistance improver (hindered amine light stabilizer) , UV absorbers, etc.), weathering agents, hindered amine compounds, infrared absorbers, heat retention agents, fillers, metal organic acid salts, basic organic acid salts and overbased organic acid salts, hydrotalcite compounds, epoxy compounds, β-diketone compound, polyhydric alcohol, halogen oxyacid salt, sulfur-based, phenol-based and phosphite-based antioxidants, heat stabilizer, lubricant, antistatic agent, colorant, anti-blocking agent) Can do. Moreover, the agricultural film of Embodiment 2 can be provided with the same antifogging coating layer as described for the agricultural polyolefin-based multilayer film of Embodiment 1.
Moreover, the agricultural film of Embodiment 2 can have a multilayer structure similar to that described for the agricultural polyolefin-based multilayer film of Embodiment 1.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these.

(1) Preparation of laminated film
As a three-layer inflation molding apparatus, a 100 mmφ (made by Pla Koken Co., Ltd.) was used for a three-layer die, and the extruder used two 30 mmφ (made by Pla Giken Co., Ltd.) tube outer layers and an intermediate layer of 40 mmφ (Plastic Corp. Manufactured by Giken Co., Ltd.) Outer inner layer extruder temperature 180 ° C., intermediate layer extruder temperature 170 ° C., die temperature 180-190 ° C., blow ratio 2.0-3.0, take-off speed 3-7 m / min, thickness 0 A three-layer laminated film composed of the components shown in Tables 1 to 5 at 15 mm was obtained. Since these films are used with the end of the tube cut open when the house is stretched, the tube outer layer during film formation becomes the inner layer (inner surface) of the house when stretched when unfolded.
In addition, about Examples 13-15 and Reference Examples 1-2, the single layer film was produced on said conditions.

[Composition] Addition amounts are as described in each table.
HP-LDPE: Branched polyethylene produced with a high-pressure radical catalyst (MFR: 0.8 g / 10 min, density 0.922) “F022NH” manufactured by Ube Maruzen Polyethylene
Metallocene PE: ethylene / α-olefin copolymer produced with a metallocene catalyst (MFR: 2.0 g / 10 min, density 0.91307) Kernel “KF270” manufactured by Nippon Polychem
EVA1: vinyl acetate content = 15% by weight: LV430: EVA manufactured by Nippon Polyethylene Co., Ltd .: vinyl acetate content = 18% by weight: 7350F: EVA3 manufactured by FORMOSA: vinyl acetate content = 18% by weight: VF218G: Ube Maruzen Polyethylene Co., Ltd. EVA4: vinyl acetate content = 20 wt%: VF120T: Ube Maruzen Polyethylene Co., Ltd. EVA5: vinyl acetate content = 21 wt%: V211N: Ube Maruzen Polyethylene Co., Ltd. EVA6: vinyl acetate content = 24 wt%: VF324G : Ube Maruzen Polyethylene Co., Ltd.

Synthetic hydrotalcite A: “DHT-4A” manufactured by Kyowa Chemical Industry Co., Ltd.

Ultraviolet absorber A: Triazine type ultraviolet absorber: UV-1164 (2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5-5 manufactured by Cytec Co., Ltd. (Octyloxy) phenol)

Ethylene / cyclic aminovinyl copolymer: “XJ100H” (MFR = 3 g / 10 minutes (190 ° C., JIS-K6760), density = 0.931 g / cm3 (JIS-K6760), manufactured by Nippon Polyethylene Co., Ltd.) Compound content = 5.1% by weight (0.7 mol%), proportion of cyclic aminovinyl compound present in isolation = 90 mol%, melting point = 111 ° C.)

Light stabilizer A: tinuvin NOR 371 FF (light stabilizer manufactured by BASF)

Spherical amorphous aluminosilicate A: JC-50: Spherical amorphous aluminosilicate B: JC-20: Mizusawa Chemical Co., Ltd. Spherical amorphous aluminosilicate C: JC -30: Cubic amorphous aluminosilicate manufactured by Mizusawa Chemical Co., Ltd. A: AMT100R: Water-containing amorphous silicon oxide manufactured by Mizusawa Chemical Co., Ltd. A: K-300: Water-containing manufactured by Mizusawa Chemical Co., Ltd. Amorphous silicon oxide B: P-73: manufactured by Mizusawa Chemical Co., Ltd. Amorphous aluminosilicate A: HSZ-920NHA: manufactured by Tosoh Corporation

(2) Surface treatment of film
The outer layer surface of the obtained tubular film was subjected to corona discharge treatment at a discharge voltage of 120 V, a discharge current of 4.7 A, and a line speed of 10 m / min, and the “wetting index” according to JIS-K6768 was measured, and the value was confirmed. .

(3) Formation of anti-fogging coating film
Colloidal silica, a thermoplastic resin, a crosslinking agent and a liquid dispersion medium were blended to obtain an antifogging agent composition.
The antifogging agent composition was blended as follows.
Inorganic colloidal sol (colloidal silica) 4.0
Thermoplastic resin (Sanmor SW-131) 3.0
Cross-linking agent (TAZM) 0.1
Dispersion medium (water / ethanol = 3/1) 93
(Note) The amount of inorganic colloidal sol is indicated by the amount of inorganic particles, and the amount of thermoplastic resin is indicated by the solid content of the polymer.
Colloidal silica: Snowtex 30 manufactured by Nissan Chemical Co., Ltd., average particle size 15 mμ
Sunmole SW-131: Sanyo Chemical Co., Ltd. acrylic emulsion
T.A. A. Z. M: Aziridine-based compound manufactured by Mutual Pharmaceutical Company
The anti-fogging agent composition was applied to the surface of the film surface-treated in (2) using a # 5 bar coater. The applied film was kept in an oven at 80 ° C. for 1 minute to volatilize the liquid dispersion medium to form an antifogging coating film. The thickness of the coating film of each obtained film was about 1 μm.

  A test was conducted using the film obtained above. In addition, the same effect is acquired even if it is the combination other than the resin used this time, an additive, or the film thickness different from this time, unless the summary is changed. The measurement method for each test is shown below.

550 nm linear light transmittance (%) measurement:
A laminated film obtained by three-layer inflation molding (after forming (coating) an antifogging coating film on the inner layer side surface) is subjected to spectrophotometer (manufactured by Shimadzu Corporation, UV-2450 type) at each sample temperature. The linear light transmittance (%) at a wavelength of 555 nm was measured.

Blocking resistance test between house outer layer surfaces:
Each film sample was wound around the pipe used for the aggregate of an agricultural house, processed in an 80 degreeC oven for 4 hours, and the peeling condition was confirmed based on the following reference | standard.
Score standard:
9 points: No fusion
8 points: fusion, peel off when rotating
7 points: fused, peeled off by its own weight
6 points: fused, peeled off by hand
5 points: There is fusion, and it is necessary to put effort into peeling
4 points: fused, can be removed, but the film is torn
3 points: melting
2 points: melting part is more than half
1 point: completely melted and attached to the mandrel

Creep resistance test:
With reference to JIS K7115, a creep resistance test was performed at a set temperature = 40 ° C., a sample shape of 5 mm × 200 mm, a marked line interval of 50 mm, a load period of 72 hours, and a load of 300 g, and the elongation percentage (%) was measured.

[Examples 1-5, Comparative Examples 1-2]
When spherical amorphous aluminosilicate having a particle size of 2 μm, 3 μm, and 5 μm is used (Examples 1, 2 and 4), when cubic amorphous aluminosilicate is used (Example 3), amorphous It shows in Tables 1-3 about the case where the quality aluminosilicate A is used (Example 5) and the case where another filler is used (Comparative Examples 1-2).

[Examples 6 to 12, Comparative Examples 3 to 4]
Table 4 shows the results of examining the effects of the types and amounts of EVA and aluminosilicate used in the intermediate layer of the multilayer film, and Table 5 shows the results of examining the relationship between the types of EVA and the creep test.

[Examples 13-15, Reference Examples 1-2]
Table 6 shows the results of the blocking test of the agricultural polyolefin monolayer film of the present invention.

Thus, the agricultural film of the present invention is excellent in not only good temperature-sensitive light-shielding properties but also anti-blocking properties and creep-proof properties, and the examples show that it can be suitably used as an agricultural film. On the other hand, when an addition method other than the present invention is used (Comparative Examples 1 to 4), the temperature-sensitive light-shielding property and transparency at room temperature are inferior, or the creep resistance property is lowered. There is a problem.
The agricultural film of the present invention having excellent temperature-sensitive light-shielding properties is a very useful agricultural film that takes into consideration not only light-shielding applications at high temperatures in summer but also light shortages in winter. In addition, the agricultural film of the present invention may be transparent, satin or semi-satin as long as the effects of the present invention are not impaired, and should be suitably used for applications such as house, tunnel, mulching, and bag hanging. Can do.

Claims (5)

  An agricultural polyolefin-based multilayer film having at least an outer layer, an intermediate layer, and an inner layer, wherein the outer layer is a linear low density polyethylene, a low density polyethylene, or an ethylene vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight ( Provided that the weight of the ethylene vinyl acetate copolymer is at least one polyethylene-based resin selected from the group consisting of ethylene resin and the intermediate layer is ethylene having a vinyl acetate content of 1 to 20% by weight. It contains a vinyl acetate copolymer (A) (provided that the weight of the ethylene vinyl acetate copolymer (A) is 100% by weight), and the inner layer is linear low density polyethylene, low density polyethylene or vinyl acetate. Is it an ethylene vinyl acetate copolymer with a content of 1 to 10% by weight (however, the weight of the ethylene vinyl acetate copolymer is 100% by weight)? And also contains at least one polyethylene resin is selected, containing amorphous aluminosilicate particles to at least the intermediate layer, the multilayer film.   The agricultural polyolefin-based multilayer film according to claim 1, wherein the intermediate layer contains the amorphous aluminosilicate particles in an amount of 0.1 to 50 parts by weight with respect to 100 parts by weight of the ethylene vinyl acetate copolymer (A). The agricultural film of Claim 1 or 2 whose BET specific surface area of the said amorphous aluminosilicate particle | grain is 100 (m < ² > / g) or less.   The agricultural film according to any one of claims 1 to 3, wherein the amorphous aluminosilicate particles are spherical amorphous aluminosilicates.   An agricultural film containing spherical amorphous aluminosilicate particles having an average particle diameter of 0.01 to 50 μm.