JP6956557B2 - Light-transmitting hygroscopic film and its manufacturing method - Google Patents

Description

The present invention relates to a light-transmitting hygroscopic film and a method for producing the same.

As a film used in the fields of pharmaceuticals, electronic parts, precision machinery, etc., a film having transparency and hygroscopicity may be used.

For example, in Patent Document 1, a transparent hygroscopic composition containing (A) a transparent polymer containing (B) a hygroscopic agent having an average particle size of 0.3 μm or less and a film formed from the composition have excellent transparency. It is described that it exhibits hygroscopicity and is suitable for application to a sealing material such as an organic EL (electroluminescence) element.

In the examples of Patent Document 1, (A) a styrene-1,3-butadiene copolymer is used as the transparent polymer, and (B) barium oxide, silica, or both of them are used as the hygroscopic agent. Verification has been carried out, and it has been reported that a flexible film having a transparency of less than 5% as a haze value and a hygroscopicity of 4% or more was obtained.

A method for producing a small particle size zeolite is described in Patent Documents 2 and 3.

Japanese Unexamined Patent Publication No. 2006-272190 Japanese Unexamined Patent Publication No. 2011-246292 Japanese Unexamined Patent Publication No. 2013-49602

The detailed specifications regarding barium oxide and silica are unclear in Patent Document 1, and the total light transmittance of the obtained film is not described. According to the studies by the present inventors, it has been found that the total light transmittance of the film obtained according to the technique of Patent Document 1 is not so high and is not suitable for application as a protective film for, for example, an organic EL element.

The present invention has been made in an attempt to improve the above-mentioned prior art. Therefore, an object of the present invention is to provide a light-transmitting moisture-absorbing film having high transparency evaluated by total light transmittance and haze and having a large saturated moisture absorption amount, and a method for producing the same.

The present invention is as follows.

[1] (A) 100 parts by mass of zeolite having an average particle size D50 of 100 nm or less,
(B) Oxides of one or more elements selected from Al, Si, Ti, and Zr having an average particle size D50 of 100 nm or less (excluding zeolite) 0.1 parts by mass or more and 10 parts by mass or less ,
(C) 1 part by mass or more and 20 parts by mass or less of an ester compound having an HLB value of 5 or less, and (D) 50 parts by mass or more and 150 parts by mass or less of a thermoplastic resin containing an ethylene unit.
A light-transmitting moisture-absorbing film in which the zeolite (A), the oxide (B), and the ester compound (C) are dispersed in the thermoplastic resin (D).

[2] The film according to [1], wherein the zeolite (A) is hydrophilic.

[3] The film according to [1], wherein the oxide (B) is silica having an average particle size D50 of 1 nm or more and 20 nm or less.

[4] The film according to [1], wherein the ester compound (C) is a monoester of an alkylene glycol having 2 or more and 6 or less carbon atoms and a fatty acid having 15 or more and 21 or less carbon atoms.

[5] The thermoplastic resin (D) is selected from low-density polyethylene, linear low-density polyethylene, ethylene- (meth) acrylic acid alkyl ester copolymer, and ethylene-vinyl acetate copolymer [1]. ] The film described in.

[6] A method for producing a light-transmitting hygroscopic film.
(A) Zeolite and
(B) Oxides of one or more elements selected from Al, Si, Ti, and Zr (excluding zeolite), and
(C) Ester compounds with an HLB value of 5 or less and
(D) A thermoplastic resin containing ethylene units and
To obtain a composition for a light-transmitting hygroscopic film, and to form the composition for a light-transmitting hygroscopic film into a film.
The average particle size D50 of the zeolite (A) contained in the light-transmitting moisture-absorbing film is 100 nm or less, and the average particle size D50 of the oxide (B) contained in the light-transmitting moisture-absorbing film is 100 nm or less. be,
The method.

[7] The method according to [6], wherein the zeolite (A) before the mixing contains at least an agglomerate that is crushed during the mixing.

[8] The method according to [6] or [7], wherein the bulk density of the zeolite (A) before the mixing is 0.40 g / ml or more.

[9] The zeolite (A) is obtained by dispersing the zeolite (A) having a low bulk density in a liquid to form a slurry, and then the zeolite (A) is consolidated from the liquid or separated by spray drying. The method according to [8].

[10] To obtain the composition for a light-transmitting moisture-absorbing film, the zeolite (A), the oxide (B), and the ester compound (C) are premixed to obtain a premixture, and the above. The method according to any one of [6] to [9], which comprises kneading the premix and the thermoplastic resin (D).

[11] An organic EL element comprising the film according to any one of [1] to [5].

The light-transmitting moisture-absorbing film of the present invention has high transparency evaluated by the total light transmittance and haze, and has a large saturated moisture absorption amount. Therefore, the light-transmitting moisture-absorbing film is suitable for application in fields such as a film for encapsulating an organic EL element and a hermetically sealed package for pharmaceutical products.

FIG. 1 is an image diagram showing a dispersed state of the light-transmitting moisture-absorbing film of the present invention. FIG. 2 is an image diagram showing a dispersed state of the light-transmitting hygroscopic film when the ester compound (C) is not used. FIG. 3 is an image diagram of a step of obtaining a premixture of zeolite (A) and oxide (B) in the method for producing a light-transmitting moisture-absorbing film of the present invention. FIG. 4 is a schematic view of a display device having the light-transmitting moisture-absorbing film of the present invention. FIG. 5 is a schematic view of a packaging laminate having the light-transmitting moisture-absorbing film of the present invention.

<Light transmissive moisture absorbing film>
The light-transmitting moisture-absorbing film of the present invention
(A) 100 parts by mass of zeolite having an average particle size D50 of 100 nm or less,
(B) Oxides of one or more elements selected from Al, Si, Ti, and Zr (excluding zeolite) 0.1 parts by mass or more and 10 parts by mass or less,
(C) 1 part by mass or more and 20 parts by mass or less of an ester compound having an HLB value of 5 or less, and (D) 50 parts by mass or more and 150 parts by mass or less of a thermoplastic resin containing an ethylene unit.
Zeolite (A), oxide (B), and ester compound (C) are dispersed in the thermoplastic resin (D).

In the light-transmitting hygroscopic film of the present invention, zeolite (A) functions as a hygroscopic agent. Therefore, it is preferable to use hydrophilic zeolite as described later. On the other hand, in the present invention, since the thermoplastic resin (D) in which the zeolite is dispersed is generally hydrophobic, the zeolite (A) is contained in the thermoplastic resin (D) in a dispersed state to obtain high transparency. It was difficult to obtain.

However, in the present invention, by coexisting the oxide (B) and the ester compound (C), the zeolite (A) is made into a highly dispersed state, preferably primary particles, in the hydrophobic thermoplastic resin (D). It is possible to disperse in a close state. As a result, the light-transmitting moisture-absorbing film of the present invention can exhibit a high degree of moisture-absorbing ability as well as excellent transparency.

In the conventionally known light-transmitting moisture-absorbing film, the affinity between the hygroscopic agent and the matrix material is insufficient, and a strong stress is applied to these to knead, disperse and distribute them. In the resulting film, as shown in FIG. 2, voids 5 are formed at the interface between the hygroscopic agent (for example, zeolite 1) and the matrix material (for example, thermoplastic resin 4), and the presence of the voids 5 is present. The transparency of the film was reduced.

On the other hand, in the light-transmitting moisture-absorbing film 10 of the present invention shown in FIG. 1, the ester compound 3 having a function of improving the compatibility between the zeolite 1 and the thermoplastic resin 4 was allowed to coexist. Then, the compatibility between the zeolite 1 and the thermoplastic resin 4 was remarkably improved, and the zeolite 1 could be highly dispersed in the thermoplastic resin 4 without requiring the voids at the interface. And by doing this, high transparency was achieved. It is considered that this phenomenon is caused by the presence of the ester compound 3 at the interface between the two.

Further, in the light-transmitting moisture-absorbing film of the present invention, the zeolite (A) is dispersed and distributed in the thermoplastic resin (D) in a highly dispersed state. The reason for this phenomenon is not clear, but it can be considered, for example, by the following mechanism of action. However, the present invention is not bound by any particular theory.

Zeolites are considered to exist alone as secondary particles, which are aggregates of primary particles, and in a state in which the secondary particles are further aggregated. FIG. 3A shows secondary particles in which the primary particles of zeolite 1 are aggregated. When stress is applied to this, the agglomerated particles are crushed to form primary particles (FIG. 3 (b)). However, it is considered that the primary particles reaggregate and return to the state of the secondary particles (FIG. 3A) when the stress is released.

On the other hand, when suitable fine particles of oxide 2 are present together with zeolite 1, the oxide 2 adheres to the surface of zeolite 1 (FIG. 3 (c)). When stress is applied in this state, the primary particles obtained by crushing the agglutinated particles do not reaggregate. It is presumed that the oxide 2 functions as an anti-reaggregation agent (FIG. 3 (d)).

Hereinafter, the present invention will be described in detail with a focus on preferred embodiments thereof.

[Zeolite (A)]
The zeolite (A) in the light-transmitting moisture-absorbing film of the present embodiment is a zeolite particle having an average particle diameter D50 of 100 nm or less.

Zeolites are crystalline and pore-rich particulate matter used to separate molecules according to their size. Zeolites have a structure having uniform pores, absorb small molecules entering the cavities of the pores, and have a kind of sieving action, and are therefore useful as a hygroscopic agent. The pore (absorption port) diameter of the zeolite (A) in the present embodiment may be 0.3 nm or more and 1 nm or less, and may be 0.3 nm or more and 0.5 nm or less.

The average particle size D50 of the zeolite (A) means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method. The average particle size D50 of the zeolite (A) in the present embodiment is required to be 100 nm or less in order for the film in which the zeolite (A) is dispersed in the thermoplastic resin (D) to exhibit a high degree of transparency. The average particle size D50 of the zeolite (A) may be 80 nm or less, 70 nm or less, 60 nm or less, or 50 nm or less. The average particle size D50 of the zeolite (A) may be 5 nm or more, 10 nm, 20 nm or more, or 30 nm or more.

The value of the atomic ratio (Si / Al) of Si and Al in the zeolite (A) is arbitrary, and may be, for example, 1 or more, 2 or more, 3 or more, 5 or more, 10 or more, or 15 or more. For example, it may be 80 or less, 60 or less, 50 or less, 40 or less, or 30 or less.

As the zeolite (A) in the present embodiment, among those satisfying the above conditions, hydrophilic zeolite having a high affinity for water is preferable from the viewpoint of exhibiting higher hygroscopic performance, and Na-A type zeolite is particularly used. It is preferable to do so.

As the preferred zeolite (A) in the present embodiment, one produced by a known method can be used. Zeolite (A) can be produced, for example, by the methods described in Patent Document 2 (Japanese Patent Laid-Open No. 2011-246292), Patent Document 3 (Japanese Patent Laid-Open No. 2013-49602) and the like. However, as detailed below, these zeolites usually have a relatively low bulk density, and once they are lightly aggregated to a relatively high bulk density, the oxides ( It is preferable to promote the dispersion of the zeolite (A) at the time of mixing or kneading with B), the ester compound (C) and the like.

Zeolite (A) can be obtained, for example, by dispersing the raw material zeolite represented by the following formula (1) in an aqueous solution containing a silicate or aluminosilicate represented by the following formula (2) and recrystallizing it. Can be done.
aM ¹ ₂ O ・ bSiO ₂・ Al ₂ O ₃・ cMeO (1)
{In formula (1), M ¹ is an alkali metal atom, a hydrogen atom, or an ammonium ion, Me is an alkaline earth metal ion atom, a is 0.01 to 1, and b is 1 to 80. c is 0 to 1. }
dM ² ₂ O ・ eAl ₂ O ₃・ fSiO ₂・ gH ₂ O (2)
{In formula (2), the ratio d / g is 0.00035 to 0.02000, the ratio e / g is 0 to 0.00025, and f / g is 0.0001 to 0.025. }

B in the above formula (1) may be, for example, 2 to 60 or 20 to 80. c may be, for example, 0.01 to 1. The ratio d / g in the above formula (2) may be, for example, 0.003 to 0.010. The ratio e / g may be, for example, 0 or 0.000003 to 0.000250. The ratio f / g may be, for example, 0.0001 to 0.0160 or 0.006 to 0.025.

As the raw material zeolite of the above formula (1), for example, NaSiAlO ₄ , NaSi ₁₂ AlO ₂₆ , NH ₄ Si ₁₉ AlO _{40 and the} like can be used. The silicate of the formula (2), for _{example, 0.292Na 2 O · hSiO 2 ·} 55.5H 2 O (h = 0.400,0.650,0.800, or 1.00), _INA 2 O _{· 0.650SiO 2 · 55.5H 2 O (} i = 0.165 or 0.55), or the like can be used. Aluminosilicate of formula (2), for _{example, 405Na 2 O · jAl 2 O} 3 · kSiO 2 · 29,900H 2 O ((j, k) = (1,23), (1,51), ( 2,23), or (2,51)) and the like can be used.

As the zeolite (A) in the present embodiment, the zeolite (A) obtained as described above may be used after being subjected to ion exchange, pulverization, or both.

The content ratio of zeolite (A) in the light-transmitting moisture-absorbing film of the present embodiment is 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, and 40% by mass with respect to the total mass of the film. It may be 50% by mass or more, 60% by mass or more, or 70% by mass or more, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass. % Or less, or 20% by mass or less.

[Oxide (B)]
The oxide (B) in the light-transmitting hygroscopic film of the present embodiment is an oxide of one or more elements selected from Al, Si, Ti, and Zr having an average particle diameter D50 of 100 nm or less (however, zeolite). ), Which may be alumina, silica, or titania, and in particular silica.

The oxide (B) may be in the form of particles.

In the light-transmitting hygroscopic film of the present embodiment, the oxide (B) prevents the zeolite (A) from re-aggregating after being once crushed, and the zeolite (A) is contained in the thermoplastic resin (D). It has a function of distributed distribution in a highly dispersed state.

That is, it is considered that the zeolite alone exists in a state where the secondary particles, which are aggregates of the primary particles, and the secondary particles are further aggregated. When stress is applied to the aggregated particles of zeolite, the aggregated particles are crushed to form primary particles. However, it is considered that these primary particles reaggregate and return to the state of secondary particles when the application of stress is released.

On the other hand, when the fine particles of the oxide (B) specified in the present embodiment are present together with the zeolite (A) in the aggregated state, the oxide (B) adheres to the surface of the zeolite (A). When stress is applied in this state, the primary particles obtained by crushing the aggregated particles of zeolite (A) do not reaggregate.

Therefore, the average particle size D50 of the oxide (B) is larger than the average particle size D50 of the zeolite (A) from the viewpoint of facilitating the effective adhesion of the oxide (B) to the surface of the zeolite (A). Small is preferable. Specifically, it may be, for example, 1 nm or more, 2 nm or more, 3 nm or more, or 5 nm or more, and may be, for example, 30 nm or less, 20 nm or less, or 15 nm or less. The average particle size D50 of the oxide (B) has the same meaning as the average particle size D50 of the zeolite (A).

The oxide (B) is more preferably hydrophobic having a phenyl group on its surface. The other aspect is arbitrary. For example, the oxide (B) may be porous or non-porous, and its density, specific surface area, and the like may be arbitrary.

The content ratio of the oxide (B) in the light-transmitting moisture-absorbing film of the present embodiment is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the zeolite (A). In order to maintain the dispersion of the zeolite (A) in the thermoplastic resin (D) described later in a good state, the content ratio of the oxide (B) is 0. It needs to be 1 part by mass or more, and preferably 0.2 part by mass or more, 0.3 part by mass or more, 0.4 part by mass or more, or 0.5 part by mass or more. On the other hand, from the viewpoint of minimizing the oxide (B) that does not contribute to the dispersion of the zeolite (A) and ensuring the transparency and processability of the obtained light-transmitting moisture-absorbing film, the content ratio of the oxide (B) is , 10 parts by mass or less, preferably 5 parts by mass or less, 3 parts by mass or less, 2 parts by mass or less, or 1 part by mass or less with respect to 100 parts by mass of zeolite (A). good.

[Ester compound (C)]
The ester compound (C) in the present embodiment is an ester compound having an HLB value of 5 or less.

The HLB value of the ester compound (C) is an index indicating whether the ester compound is hydrophilic or lipophilic. When the HLB value of the ester compound (C) is 5 or less, it means that the ester compound (C) has high lipophilicity, and is, for example, a numerical value of a region used as an antifoaming agent or an emulsifier of an emulsion. Is.

The HLB value of the ester compound (C) is preferably, for example, 4.5 or less, 4.0 or less, or 3.5 or less, and for example, 2.0 or more, 2.5 or more, or 3. It may be 0 or more.

The ester compound (C) in the present embodiment is preferably a monoester compound of a polyhydric alcohol and a fatty acid. The polyhydric alcohol may be, for example, glycerin, alkylene glycol or the like. The fatty acid may be, for example, a saturated or unsaturated fatty acid having 12 or more and 24 or less carbon atoms.

The ester compound (C) may be a monoester of an alkylene glycol having 2 or more and 6 or less carbon atoms and a fatty acid having 15 or more and 21 or less carbon atoms. The alkylene glycol may be, for example, ethylene glycol, propylene glycol, diethylene glycol or the like. The above and fatty acids having 15 or more and 21 or less carbon atoms may be saturated or unsaturated, and may be, for example, stearic acid, behenic acid, or the like.

Specifically, the ester compound (C) in the present embodiment may be, for example, propylene glycol monostearate, propylene glycol monobehenate, or the like.

The content ratio of the ester compound (C) in the light-transmitting moisture-absorbing film of the present embodiment is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the zeolite (A). The ester compound (C) is contained in order to improve the dispersed state of the zeolite (A) in the thermoplastic resin (D), which will be described later, and to prevent voids from being interposed between the thermoplastic resin (D) and the zeolite (A). The ratio needs to be 1 part by mass or more with respect to 100 parts by mass of the zeolite (A), preferably 2 parts by mass or more, 3 parts by mass or more, 4 parts by mass or more, or 5 parts by mass or more. It may be there. On the other hand, from the viewpoint of reducing the amount of the ester compound (C) that does not contribute to the dispersion of the zeolite (A) as much as possible, the content ratio of the ester compound (C) is 20 parts by mass or less with respect to 100 parts by mass of the zeolite (A). It is necessary that the amount is 15 parts by mass or less, preferably 10 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, or 6 parts by mass or less.

[Thermoplastic resin (D)]
The thermoplastic resin (D) in the light-transmitting moisture-absorbing film of the present embodiment is a thermoplastic resin containing ethylene units. A thermoplastic resin containing an ethylene unit is preferable as a matrix material in the light-transmitting moisture-absorbing film of the present embodiment because it has high transparency and an appropriate "waist".

Examples of the thermoplastic resin (D) in the present embodiment include polyolefin-based resins, and may be, for example, thermoplastic polyethylene, a thermoplastic resin containing ethylene units and ester units, and the like.

Examples of the polyolefin-based resin include polyethylene-based resins, polypropylene-based resins, and copolymers of ethylene and oxygen-containing ethylenically unsaturated monomers. Examples of the copolymer of ethylene and the oxygen-containing ethylenically unsaturated monomer include EVOH (ethylene-vinyl alcohol copolymer) and the like.

In the present specification, the polyethylene-based resin contains a repeating unit of an ethylene group in the main chain of the polymer in an amount of 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more. Resins, such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-acrylic acid copolymer (EAA), ethylene- Methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene vinyl acetate copolymer (EVA), carboxylic acid-modified polyethylene, carboxylic acid-modified ethylene It is selected from the group consisting of vinyl acetate copolymers, derivatives thereof, and mixtures thereof.

In the present specification, the polypropylene-based resin is a resin containing 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more of repeating units of propylene groups in the main chain of the polymer. Yes, for example, polypropylene (PP) homopolymers, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid-modified polypropylene, derivatives thereof, and mixtures thereof.

The thermoplastic polyethylene may be, for example, low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, or the like.

The thermoplastic resin containing the ethylene unit and the ester unit may be, for example, an ethylene- (meth) acrylic acid alkyl ester copolymer, an ethylene-vinyl acetate copolymer, or the like. The ethylene- (meth) acrylic acid alkyl ester copolymer may be, for example, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer or the like.

The thermoplastic resin (D) in the present embodiment is preferably selected from ultra-low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-methyl acrylate copolymer.

When the light-transmitting moisture-absorbing film of the present embodiment is used as a sealing material or a protective film for an organic EL element, an ethylene-vinyl acetate copolymer may be used as the thermoplastic resin (D). The vinyl acetate content in the ethylene-vinyl acetate copolymer may be, for example, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more, for example, 60% by mass. % Or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, or 40% by mass or less.

The content ratio of the thermoplastic resin (D) in the light-transmitting moisture-absorbing film of the present embodiment is 50 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the zeolite (A). In order to exhibit the mechanical properties required for the film of the light-transmitting moisture-absorbing film of the present embodiment, the content ratio of the thermoplastic resin (D) is 50 parts by mass with respect to 100 parts by mass of the zeolite (A). The above is required, and preferably 60 parts by mass or more, 70 parts by mass or more, 80 parts by mass or more, or 90 parts by mass or more. On the other hand, from the viewpoint of containing a significant amount of zeolite (A) in the light-transmitting moisture-absorbing film of the present embodiment and fully exerting its moisture-absorbing function, the content ratio of the thermoplastic resin (D) is that of the zeolite (A). It is required to be 150 parts by mass or less with respect to 100 parts by mass, and preferably 140 parts by mass or less, 130 parts by mass or less, 120 parts by mass or less, or 110 parts by mass or less.

[Optional additive]
In addition to the above-mentioned components (A) to (D), the light-transmitting hygroscopic film of the present embodiment includes, for example, a lubricant, an antistatic agent, a mold release agent, a plasticizer, and an antioxidant, if necessary. , Antibacterial agents, antifungal agents, UV absorbers and other optional additives can be further contained.

[Thickness of light-transmitting moisture-absorbing film]
The thickness of the light-transmitting moisture-absorbing film of the present embodiment may be appropriately set in consideration of the purpose of use, desired transparency, desired amount of moisture absorption, and the like. When the light-transmitting moisture-absorbing film of the present embodiment is applied to, for example, a protective film for an organic EL element, the thickness of the film may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more, for example. , 200 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

[Skin layer]
The light-transmitting moisture-absorbing film of the present embodiment may have a skin layer on one side or both sides thereof. In the skin layer, the film-forming stability of the light-transmitting moisture-absorbing film of the present embodiment is improved, surface smoothness is imparted, zeolite (A) in the film is prevented from falling off, and zeolite (A) is directly exposed to the outside. At least one of prevention, improvement of mechanical strength (for example, tensile strength) when the light-transmitting moisture-absorbing film of the present embodiment is used as a packaging container, and improvement of heat-sealing strength with another film or laminate. Has a function.

As the resin constituting the skin layer, a resin generally used for a film can be used. When the light-transmitting moisture-absorbing film has skin layers on both sides, the resins constituting the skin layers may be the same or different.

Examples of the resin constituting the skin layer include polystyrene-based resin, polyester-based resin, acrylic-based resin, polyamide-based resin, polyvinyl alcohol-based resin, polyurethane-based resin, polyolefin-based resin, polycarbonate resin, polysulfone resin, and derivatives thereof. In addition, a mixture thereof and the like can be mentioned.

The thickness of the skin layer can be 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and can be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 15 μm or less per side. When the light-transmitting moisture-absorbing film has skin layers on both sides, the thickness of these skin layers may be the same or different.

<Manufacturing method of light-transmitting moisture-absorbing film>
In the method for producing a light-transmitting moisture-absorbing film of the present embodiment, zeolite (A), oxide (B), ester compound (C), and thermoplastic resin (D) are mixed in any order to carry light. This includes obtaining a composition for a moisture-absorbing film and molding the composition for a light-transmitting moisture-absorbing film into a film. The light-transmitting moisture-absorbing film obtained by the method of the present embodiment may be the above-mentioned light-transmitting moisture-absorbing film. Therefore, the zeolite (A), oxide (B), ester compound (C), and thermoplastic resin (D) contained in the light-transmitting moisture-absorbing film obtained by the method of the present embodiment are as described above. It's okay.

The zeolite (A) and the oxide (B) used in the method of the present embodiment can be classified into desired particle sizes and then used for preparing a composition for a light-transmitting hygroscopic film.

The ester compound (C) used in the method of the present embodiment is usually supplied in the form of oil, wax, beads, granules, powder or the like. The ester compound (C) in the supplied form may be used as it is in the preparation of the composition for the light-transmitting hygroscopic film.

The thermoplastic resin (D) used in the method of this embodiment is usually supplied in the form of pellets. In the production of the composition for a light-transmitting moisture-absorbing film, the supplied form of the thermoplastic resin (D) may be used as it is, or the thermoplastic resin (D) may be powdered and used.

The light-transmitting moisture-absorbing film of the present embodiment is, for example,
Premixing step of premixing zeolite (A), oxide (B) and ester compound (C) to obtain a premixture. The premixture obtained above and the thermoplastic resin (D) are kneaded. By a method including a film forming step of obtaining a composition for a light-transmitting moisture-absorbing film, preparing a composition for a light-transmitting moisture-absorbing film, and molding the composition for a light-transmitting moisture-absorbing film obtained above into a film. Can be manufactured.

The bulk density of the zeolite (A) used in the method of the present embodiment is preferably 0.35 g / ml or more, 0.40 g / ml or more, 0.45 g / ml or more, or 0.50 g / ml or more. be. Further, the bulk density of the zeolite (A) used in the method of the present embodiment may be 1.0 g / ml or less, 0.80 g / ml or less, or 0.60 g / ml or less. The dense presence of the zeolite having such a bulk density makes it possible to effectively apply torque from a mixer or the like used for mixing, thereby facilitating dispersion in the composition. It can be easily dispersed in the composition, particularly when the zeolite (A) is dispersed in the composition in an amount of 40% by mass or more.

However, the zeolite (A) used in the method of the present embodiment can also be used at a relatively low bulk density depending on the type of the mixing device and / or the kneading device.

Zeolites (A) can be in the form of aggregates that can be crushed during mixing or kneading to obtain a composition. Zeolites (A), which are in the form of crushable aggregates, usually have a relatively high bulk density.

From the powdery zeolite (A) having a relatively low bulk density, the zeolite (A) in the aggregate form having a relatively high bulk density can be obtained. In that case, for example, zeolite (A) having a low bulk density is dispersed in a liquid to form a slurry, and then zeolite (A) is separated from the liquid. The zeolite separated from the liquid can be arbitrarily pulverized to obtain a zeolite (A) having a high bulk density. At this time, a drying step for drying the liquid contained inside the zeolite (A) can also be performed.

For example, a powdery zeolite (A) having a relatively low bulk density is dispersed in water, then dehydrated, and a compacted zeolite mass (for example, a major axis of about 50 μm to 1000 μm, particularly a major axis of 100 μm). (Approximately 200 μm) is obtained, and this is arbitrarily pulverized to obtain zeolite (A) in the form of aggregates having a relatively high bulk density. In this case, it is preferable to dry before and / or after pulverization in order to remove the water contained inside the zeolite (A). Prior to pulverization, primary drying may be performed to remove the water content of the dehydrated zeolite mass, and the water contained inside the zeolite (A) may be removed before pulverization after the primary drying and / or after pulverization. Zeolite (A) may be further dried to remove it. At the time of dehydration, a consolidated form of zeolite can be obtained by a well-known solid-liquid separation method, for example, filtration, centrifugation or the like.

Further, it is also possible to obtain zeolite (A) in the form of an agglomerate that can be crushed by separating the liquid by a spray-drying method after obtaining the slurry, and having a high bulk density. In this case, in order to obtain a crushable agglomerate (major axis of about 5 μm to 100 μm, particularly major axis of about 30 to 50 μm), for example, a zeolite slurry is sent to an atomizer rotating at a high speed of 8000 rpm to 2500 rpm, and droplets are used by centrifugal force. Aim to atomize. The atomized droplets can be dried by exposing them to hot air (for example, about 200 to 250 ° C.) in a chamber to obtain aggregates.

In order to uniformly disperse the zeolite (A) having a very small primary particle size in the film, the present inventors use a zeolite (A) having a small amount of secondary particles and aggregates, and the zeolite into the film. An attempt was made to uniformly disperse (A). However, in another study, the present inventors used zeolite (A) having a high bulk density and / or zeolite (A) in the form of agglomerates, and found that the transparency was unexpectedly high. We have found that films are easily available. Without being bound by theory, the reason for this is that upon mixing and / or kneading of zeolite (A) into the composition, such zeolite (A) is first distributed to various locations in the composition. It is considered that this is because the zeolite can be gradually crushed and dispersed in a form close to that of the primary particles during mixing and / or kneading. That is, when a zeolite (A) having a low bulk density and / or a zeolite (A) having a form close to that of primary particles is used for dispersion in the composition, it is locally dispersed from the place where it is mixed with the composition. It is believed that it will take some time for the zeolite to be totally dispersed in the composition.

[Preliminary mixing process]
In the premixing step in the method for producing a light-transmitting moisture-absorbing film of the present embodiment, the zeolite (A), the oxide (B), and the ester compound (C) are premixed to obtain a premixture.

This premixing process
It may be carried out by one-step mixing in which the three components of zeolite (A), oxide (B), and ester compound (C) are mixed at once.
It may be carried out by a two-step mixing in which the remaining components are added to the mixture obtained by mixing any two of these three components and the mixing is continued.

The light-transmitting moisture-absorbing film of the present embodiment is a high-performance light-transmitting moisture-absorbing film that has both high transparency and high moisture-absorbing ability by being manufactured through such a premixing step. Is guaranteed. This means that in the light-transmitting hygroscopic film of the present embodiment produced via this step, the zeolite (A) is dispersed in the thermoplastic resin (D) in the form of primary particles, and as a result, the zeolite (A) is dispersed in the state of primary particles. It is presumed that both excellent transparency and high hygroscopicity are exhibited.

In the premixing step of the present embodiment, the stress applied when premixing the zeolite (A), the oxide (B) and the ester compound (C) can be controlled according to the form of the zeolite (A) and the like. can. Therefore, the mixing device used for the premixing may be a Henschel mixer, a shaker, or the like. The temperature at the time of premixing may be the ambient temperature.

[Composition preparation step for light-transmitting hygroscopic film]
In the composition preparation step for a light-transmitting moisture-absorbing film in the method for producing a light-transmitting moisture-absorbing film of the present embodiment, the premix obtained above and the thermoplastic resin (D) are kneaded to absorb light-transmitting moisture. Obtain a film composition.

This step can be carried out, for example, by putting the premix, the ester compound (C), and the thermoplastic resin (D) into an appropriate kneader in no particular order and kneading them. Mixing may be performed with a pressure mixer to obtain a masterbatch, and then the masterbatch may be further kneaded with a twin-screw kneader or the like.

The mixing device used in this step may be, for example, a pressure mixer kneader (banbury, roll, kneader, etc.), an extrusion kneader, a uniaxial kneader, a biaxial kneader, or the like.

Kneading can be performed at a temperature equal to or higher than the melting point temperature of the thermoplastic resin (D). The higher the kneading temperature, the lower the viscosity of the thermoplastic resin (D) and the higher the kneading efficiency, which is advantageous. However, if the kneading temperature is excessively high, kogation occurs on the resin and the transparency of the light-transmitting hygroscopic film obtained is impaired. Therefore, it is preferable to control the kneading temperature to an appropriate temperature according to the type of the thermoplastic resin (D) used. For example, the kneading temperature of the thermoplastic resin (D) may be, for example, 60 ° C. or higher, 80 ° C. or higher, 100 ° C. or higher, 120 ° C. or higher, or 140 ° C. or higher, for example, 180 ° C. or lower, 170 ° C. or lower, Alternatively, the temperature may be 160 ° C. or lower.

[Film molding process]
The light-transmitting hygroscopic film of the present embodiment can be obtained by then molding the composition for a light-transmitting hygroscopic film obtained as described above into a film having a desired thickness.

This step may be performed as a step independent of the step of preparing the composition for the light-transmitting moisture-absorbing film of the previous step, or may be carried out as a step continuous with the previous step.

For molding the composition for a light-transmitting moisture-absorbing film into a film, for example, a pressing method, an inflation method, a casting method and the like can be mentioned. These methods may be carried out by an appropriate method according to a known technique.

[Formation of skin layer]
When the light-transmitting moisture-absorbing film of the present embodiment has a skin layer, the skin layer uses a known method, for example, a laminating method, a co-extrusion method, a casting method, an appropriate method, or the like, to absorb light-transmitting moisture. It can be formed on one side or both sides of the film.

<Application example of light-transmitting moisture-absorbing film>
Examples of application of the light-transmitting moisture-absorbing film of this embodiment are shown in FIGS. 4 and 5.

FIG. 4 is a schematic diagram of the configuration of a display device having the light transmissive moisture absorbing film of the present embodiment, for example, an organic EL element. The display device 200 in FIG. 4 has the light-transmitting moisture-absorbing film 10 of the present embodiment between the light-emitting display element 110 and the base material 120.

FIG. 5 is a schematic diagram of the configuration of the packaging laminate having the light-transmitting moisture-absorbing film of the present embodiment. The packaging laminate 300 in FIG. 5 includes the light-transmitting moisture-absorbing film 10 of the present embodiment and the transparent base film 130 laminated on both sides of the light-transmitting moisture-absorbing film 10.

The packaging laminate having the light-transmitting moisture-absorbing film of the present embodiment may be used as a packaging bag. Specifically, for example, the packaging bag includes one or more of the packaging laminates of FIG. 5, and a part of the one or more packaging laminates on the light-transmitting moisture-absorbing film side. It may be formed in a bag shape by being heat-sealed with another part of this laminate or another film. This packaging bag may be a packaging bag containing the contents and seals the contents.

Experiment A. Experiment on the type of ester compound (C) <Example 1>
1. 1. Premixing step 100 parts by mass of Na-A type zeolite (average particle size D50: 50 nm) as zeolite (A), 1 part by mass of silica (average particle size D50: 10 nm) as oxide (B), and ester compound (C). As a result, 10 parts by mass of glycerin monobehenate (manufactured by RIKEN Vitamin Co., Ltd., product name "Rikemar PB-100", HLB: 3.4) was placed in a glass bottle and premixed by shaking to obtain a premix. rice field.

2. Composition preparation step for light-transmitting moisture-absorbing film Ethylene-vinyl acetate copolymer (manufactured by Mitsui-DuPont Polychemical Co., Ltd., product name "Evaflex EV150" as the total amount of the premixture obtained above and the thermoplastic resin (D) , Vinyl acetate content: 33% by mass) was melt-kneaded at 160 ° C. using a Banbury mixer and an extrusion kneader in sequence to obtain a composition for a light-transmitting moisture-absorbing film.

3. 3. Film Molding Step The above composition for a light-transmitting moisture-absorbing film was pressed at 160 ° C. and 30 MPa to form a film to obtain a light-transmitting moisture-absorbing film having a thickness of 50 μm.

4. Evaluation (1) Transmittance and haze The film obtained above was cut into a square of 50 mm x 50 mm, and the entire film was cut out using a haze / transmittance measuring device (manufactured by Murakami Color Research Institute Co., Ltd., model name "HR-100"). The light transmittance and haze were measured. Here, the total light transmittance was measured in accordance with JIS K7361-1, and the haze was measured in accordance with JIS K7136.

(2) Saturated Moisture Absorption Amount The mass of the test piece obtained by cutting the film obtained above into a square of 100 mm × 100 mm was measured. The weighed test piece was allowed to stand in a 40 ° C. and 90% RH environment for 48 hours, and then allowed to stand in a 23 ° C. and 50% RH environment for 24 hours to allow the test piece to absorb moisture. The mass of the test piece after moisture absorption was measured, and the value calculated by the following formula was taken as the saturated moisture absorption amount.
Saturated moisture absorption (g / m ² ) = (mass after moisture absorption (g) -mass before moisture absorption (g)) / test piece area (m ² )

The saturated moisture absorption amount of the light-transmitting moisture-absorbing film test piece in this example was 5.2 g / m ² .

<Examples 2 to 5 and Comparative Examples 1 to 3>
A light-transmitting moisture-absorbing film was produced in the same manner as in Example 1 above except that the same amount of the compound shown in Table 1 was used instead of glycerin monobehenate as the ester compound (C), and the transmittance and haze were evaluated. Was done. The results are shown in Table 1. Although the oxaline-containing reactive polystyrene used in Comparative Example 1 is not an ester compound, it is described in the relevant column for convenience.

<Comparative example 4>
1. 1. Composition preparation step for light-transmitting moisture-absorbing film 50 parts by mass of Na-A zeolite (average particle size D50: 50 nm) as zeolite (A), and ethylene-vinyl acetate copolymer as thermoplastic resin (D) (Mitsui. 50 parts by mass of DuPont Polychemical Co., Ltd., product name "Evaflex EV150", vinyl acetate content: 33% by mass) is melt-kneaded at 160 ° C using a laboplast mill and a conical kneader to transmit light. A composition for a moisture absorbing film was obtained.

2. Film Molding Step The above composition for a light-transmitting moisture-absorbing film was pressed at 160 ° C. and 30 MPa to form a film to obtain a light-transmitting moisture-absorbing film having a thickness of 50 μm.

3. 3. Evaluation The transmittance and haze of the film obtained above were evaluated in the same manner as in Example 1. The results are shown in Table 1.

The abbreviations of the component names (types) in Table 1 have the following meanings.
[Zeolite]
Na-A type: Na-A type zeolite (average particle size D50: 50 nm, bulk density 0.50 g / ml)
[Oxide]
Spherical silica: Spherical silica (average particle size D50: 10 nm)
[Thermoplastic resin]
EVA: Ethylene-vinyl acetate copolymer (manufactured by Mitsui / DuPont Polychemical Co., Ltd., product name "Evaflex EV150", vinyl acetate content: 33% by mass)

The film obtained in Comparative Example 4 in which neither the oxide and the ester compound specified in the present invention were contained was colored brown, and streaky foreign matter was observed in some places. It is presumed that the brown coloring is due to the burning of the zeolite during kneading. It is presumed that the streak-like foreign matter had insufficient dispersibility of the zeolite, and the zeolite that was not dispersed and aggregated in the thermoplastic resin matrix was observed as a streak-like substance.

The films of Comparative Examples 1 to 3 containing the oxide specified in the present invention but not the ester compound specified in the present invention had insufficient haze. It is presumed that this was due to the formation of voids at the interface between the zeolite and the thermoplastic resin.

On the other hand, the films of Examples 1 to 5 having the predetermined constitution of the present invention did not show any coloring and had good transparency and haze.

Experiment B. Experiment on bulk density of zeolite (A) 1. Adjustment of bulk density 50 grams of Na-A type zeolite (average primary particle size D50: 50 nm, bulk density 0.10 g / ml) and pure water are placed in a container and stirred, and then the obtained slurry is allowed to stand to be zeolite. Was precipitated. The supernatant was discarded and then pressure was applied to dehydrate. The dehydrated Na-A zeolite was dried in a vacuum dryer at 30 ° C. for 24 hours. The dried massive Na-A zeolite was pulverized to obtain an agglomerate having a particle size of about 50 μm. The aggregated Na-A type zeolite was dried in a vacuum dryer at 200 ° C. for 24 hours to remove water remaining in the crystal pores. By this consolidation method, Na-A type zeolite having a bulk density of 0.50 g / ml was obtained.

By adjusting the amount of water used to obtain the slurry, a Na-A type zeolite having a bulk density of 0.20 g / ml and a Na-A type zeolite having a bulk density of 0.30 g / ml were obtained by a coagulation crushing method.

Further, 50 grams of Na-A type zeolite (average primary particle size D50: 50 nm, bulk density 0.10 g / ml) and pure water are placed in a container and stirred, and then Na is obtained from the obtained slurry by the spray-drying method described above. -A-type zeolite was separated to obtain Na-A-type zeolite having a bulk density of 0.50 g / ml.

2. Premixing Steps As the zeolite (A), the bulk densities are 0.10 g / ml (Example 6), 0.20 g / ml (Example 7), 0.30 g / ml (Example 8), and 0.50 g / ml. As Na-A-type zeolite by the compaction method of ml (Example 9) and Na-A-type zeolite by the spray-dry method having a bulk density of 0.50 g / ml (Example 10), 100 parts by mass as oxide (B). 1 part by mass of fine silica (average particle size D50: 10 nm) and 10 parts by mass of glycerin monobehenate (manufactured by RIKEN Vitamin Co., Ltd., product name "Rikemar PB-100", HLB: 3.4) as ester compound (C). Was placed in a glass bottle and premixed by shaking for 1 to 2 minutes to obtain a premix.

3. 3. Composition preparation step for light-transmitting moisture-absorbing film Ethylene-vinyl acetate copolymer (manufactured by Mitsui-DuPont Polychemical Co., Ltd., product name "Evaflex EV150") as the thermoplastic resin (D) and the total amount of the premix obtained above. , Vinyl acetate content: 33% by mass) was melt-kneaded at 160 ° C. for 10 minutes using a Banbury mixer to obtain a masterbatch. The masterbatch was further subjected to a biaxial kneader to obtain a composition for a light-transmitting moisture-absorbing film.

4. Film Molding Step The above composition for a light-transmitting moisture-absorbing film was pressed at 160 ° C. and 30 MPa to form a film to obtain a light-transmitting moisture-absorbing film having a thickness of 50 μm.

5. Evaluation The transmittance and haze of the film obtained above were evaluated in the same manner as in Example 1. The results are shown in Table 2.

As can be seen from this result, a film using zeolite (A) having a bulk density adjusted to 0.5 g / ml when produced by mixing and kneading under the same conditions (Examples 9 to 10) The haze value obtained was lower than that of the films (Examples 6 to 8) using the zeolite (A) having a bulk density of 0.3 g / ml or less. When zeolite (A) having a bulk density adjusted to 0.5 g / ml was used, a highly transparent film could be obtained under relatively simple mixing and kneading conditions.

1 Zeolite (A)
2 Oxide (B)
3 Ester compound (C)
4 Thermoplastic resin (D)
5 Void 10 Light-transmitting moisture-absorbing film 110 Light-emitting display element 120 Base material 130 Transparent base material film 200 Display device 300 Packaging laminate

Claims (11)

(A) 100 parts by mass of zeolite having an average particle size D50 of 100 nm or less,
(B) Oxides of one or more elements selected from Al, Si, Ti, and Zr having an average particle size D50 of 100 nm or less (excluding zeolite) 0.1 parts by mass or more and 10 parts by mass or less ,
(C) 1 part by mass or more and 20 parts by mass or less of an ester compound having an HLB value of 2 or more and 5 or less, and (D) a thermoplastic resin containing 50 parts by mass or more and 150 parts by mass or less of a thermoplastic resin containing ethylene units. ), The zeolite (A), the oxide (B), and the ester compound (C) are dispersed in a light-transmitting moisture-absorbing film. The film according to claim 1, wherein the zeolite (A) is hydrophilic. The film according to claim 1, wherein the oxide (B) is silica having an average particle size D50 of 1 nm or more and 20 nm or less. The film according to claim 1, wherein the ester compound (C) is a monoester of an alkylene glycol having 2 or more and 6 or less carbon atoms and a fatty acid having 15 or more and 21 or less carbon atoms. The first aspect of claim 1, wherein the thermoplastic resin (D) is selected from low-density polyethylene, linear low-density polyethylene, ethylene- (meth) acrylic acid alkyl ester copolymer, and ethylene-vinyl acetate copolymer. Film. A method for producing a light-transmitting hygroscopic film.
(A) Zeolite and
(B) Oxides of one or more elements selected from Al, Si, Ti, and Zr (excluding zeolite), and
(C) Ester compounds with an HLB value of 2 or more and 5 or less,
(D) A thermoplastic resin containing ethylene units and
To obtain a composition for a light-transmitting hygroscopic film, and to form the composition for a light-transmitting hygroscopic film into a film.
The average particle size D50 of the zeolite (A) contained in the light-transmitting moisture-absorbing film is 100 nm or less, and the average particle size D50 of the oxide (B) contained in the light-transmitting moisture-absorbing film is 100 nm or less. be,
The method. Previous zeolite before Symbol mixture (A) comprises aggregates are disintegrated during at least the mixing method according to claim 6. The method according to claim 6 or 7, wherein the bulk density of the zeolite (A) before the mixing is 0.40 g / ml or more. The zeolite (A) is obtained by dispersing the zeolite (A) having a low bulk density in a liquid to form a slurry, and then the zeolite (A) is consolidated from the liquid or separated by spray drying. The method according to claim 8. To obtain the composition for a light-transmitting moisture-absorbing film, the zeolite (A), the oxide (B), and the ester compound (C) are premixed to obtain a premixture, and the premixture and the premixture are obtained. The method according to any one of claims 6 to 9, which comprises kneading with the thermoplastic resin (D). An organic EL device comprising the film according to any one of claims 1 to 5.

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