JP6611711B2 - Hygroscopic laminate with hygroscopic film - Google Patents

Description

  The present invention relates to a hygroscopic laminate including a hygroscopic film and a substrate. In particular, the present invention relates to a hygroscopic laminate including a hygroscopic film and a base material that can be easily peeled after adhesion to the base material and hardly peels off from the base material even if the hygroscopic film absorbs moisture. .

  In an organic EL device that is a typical example of an electronic device, there is a known problem that a so-called dark spot (non-light-emitting portion) is generated due to intrusion of moisture into the organic EL element. Moreover, since the power generation cell part and the conductor part of the solar cell element are deteriorated by moisture, there is a problem that the power generation efficiency is lowered with time. Therefore, in these apparatuses, a hygroscopic material that absorbs moisture is used.

  For example, in an organic EL device, generally, a moisture absorbent or desiccant that adsorbs moisture is dispersed in a thermoplastic resin, and a molded product (called a getter material) formed into a sheet or the like is placed inside the device in a low moisture concentration atmosphere. By sealing to, deterioration due to moisture is prevented.

  As a method of incorporating a hygroscopic material in the apparatus, a method of inserting a hygroscopic material by processing a seal plate or the like, a method of bonding a sheet in which a hygroscopic agent is hardened with a binder (for example, Patent Document 1), a hygroscopic material Examples thereof include a method of laminating materials by coating (for example, Patent Document 2).

JP 2011-124216 A Japanese Patent No. 4240893

  In the method of counterboring the sealing plate and inserting the hygroscopic material, the processing cost increases and the device design is also limited.

  Furthermore, in the moisture absorption film used in an electronic device, a thermosetting resin has been used as a binder as in Patent Document 1 and Patent Document 2. This is because a chemical adsorbent that is less likely to release moisture absorbed by heat treatment or the like and has high moisture absorption performance is used as the moisture absorbent.

  That is, the moisture-absorbing chemical adsorbent expands its volume when it absorbs moisture. Therefore, when used in combination with a thermoplastic resin binder, the moisture-absorbing film itself also expands. When the hygroscopic film expands, the film is easily peeled off from the bonded base material, and therefore a thermosetting resin binder that hardly expands is used.

  However, the thermosetting resin is inferior in toughness as compared with the thermoplastic resin. For example, an epoxy resin which is a typical thermosetting resin and a low density polyethylene (LDPE) which is a typical thermoplastic resin In comparison, LDPE is not broken by Izod impact test (ASTM D638), whereas epoxy resin is broken at 16 to 533 J / m. Further, the elongation at break is about 100 to 650% for LDPE and 3 to 6% for epoxy resin.

  That is, the moisture-absorbing film described in Patent Document 1 and Patent Document 2 conventionally used in electronic devices has a problem that breakage is likely to occur due to the bending or dropping of the base material. Moreover, after adhering these hygroscopic films using a thermosetting resin to the base material, the hygroscopic film cannot be peeled off, so that there is another problem that the position of the hygroscopic film cannot be readjusted or exchanged.

The present inventors found the following present invention corresponding to said subject.
<1> a substrate, a hygroscopic film, a hygroscopic laminate having an adhesive layer between the substrate and the hygroscopic film,
The moisture-absorbing film has a moisture-absorbing layer containing a thermoplastic resin binder and a chemical adsorbent,
Hygroscopicity satisfying the following relationship, using the volume expansion coefficient X (%) of the hygroscopic film after moisture absorption, the peel adhesive strength Y (N / 25 mm) between the substrate and the hygroscopic film before the start of moisture absorption: Laminate:
Y ≧ 0.0011X ² + 0.058X−0.26 (where 0 <Y ≦ 5.00)
<2> The chemical adsorbent is selected from the group consisting of calcium oxide, barium oxide, magnesium oxide, lithium sulfate, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, gallium sulfate, titanium sulfate and nickel sulfate. The hygroscopic laminate according to <1>.
<3> The hygroscopic laminate according to the above <1> or <2>, wherein the thermoplastic resin binder is a polyolefin resin.
<4> The hygroscopic laminate according to any one of the above <1> to <3>, wherein the hygroscopic film has a skin layer containing a polyolefin resin on one side or both sides of the hygroscopic layer.
<5> An electronic device comprising the hygroscopic laminate according to any one of <1> to <4> above.
<6> The electronic device according to <5>, which is an organic EL module, an inorganic EL module, or a solar battery.

  The hygroscopic laminate provided with the hygroscopic film of the present invention has an appropriate peel adhesion strength according to the volume expansion coefficient of the hygroscopic film due to moisture absorption, so that peeling due to volume expansion does not occur, and the hygroscopic film is recycled. Peeling (rework) can be performed.

  Specifically, in the present invention, a hygroscopic film used in combination with a thermoplastic resin binder and a chemical adsorbent is used. As described above, when the moisture-absorbing film is adhered to the substrate so as to have reworkability, the moisture-absorbing film expands after moisture absorption and usually peels off from the substrate.

  On the other hand, in the present invention, even if the hygroscopic film itself expands due to moisture absorption by giving an appropriate peel adhesion strength according to the volume expansion coefficient of the hygroscopic film between the substrate and the hygroscopic film. Since peeling does not occur and the thermoplastic resin is tough, even if the hygroscopic film is bent at the time of exfoliation, etc., a hygroscopic laminate having a hygroscopic film that is resistant to cracking and breakage and can be reworked is provided. be able to.

It is the schematic of the hygroscopic laminated body of this invention. It is a figure which shows the relationship between the peeling adhesive strength before moisture absorption of a moisture absorption film about the hygroscopic laminated body of this invention, and the volume expansion coefficient after moisture absorption. It is a figure which shows a chemical adsorbent content and the relationship between the expansion coefficient of the moisture absorption film containing a chemical adsorbent.

<Hygroscopic laminate>
The hygroscopic laminate of the present invention has a base material, a hygroscopic film, and an adhesive layer between the base material and the hygroscopic film. FIG. 1 is a schematic view of a hygroscopic laminate (10) of the present invention, in which a hygroscopic film (2) comprising two skin layers (21, 23) and a hygroscopic layer (22) comprises a substrate (1) and It adheres via the adhesive layer (3).

  The moisture-absorbing film and the substrate are adhered by the adhesive layer, but the moisture-absorbing film expands by absorbing moisture, and the moisture-absorbing film has a force to peel from the substrate. Therefore, the hygroscopic film is bonded to the base material with an appropriate adhesive strength so as not to peel from the base material even after the hygroscopic film expands and to maintain the reworkability of the hygroscopic film.

The present inventors have found that this appropriate adhesive strength varies greatly depending on the expandability of the hygroscopic film, the volume expansion coefficient after moisture absorption of the hygroscopic film, the peel adhesion strength before moisture absorption of the hygroscopic film, and the following relationship. We found a very useful hygroscopic laminate when satisfying the formula:
Y ≧ 0.0011X ² + 0.058X−0.26 (where 0 <Y ≦ 5.00)

  This relational expression is derived by creating an approximate curve by polynomial approximation (degree 2) using the approximate line addition function of Excel 2003 based on the results obtained in the following examples.

  FIG. 2 shows a graph of X and Y of this relational expression.

In the XY graph of FIG. 2, the region where Y ≧ 0.0011X ² + 0.058X−0.26 (0 <Y ≦ 5.00) does not peel even when the film absorbs moisture, which is safe. It can be said that it shows an area. Therefore, when 0.10, 0.20, 0.30, 0.50, 1.00, 1.50, or 2.00 is added to the right side of this relational expression, the above relational expression is It can be said that it shows a safe region that is more difficult to peel off. However, those skilled in the art know that the above relational expression is created only from the test examples that were not actually peeled off in the examples, and therefore −0.15, −0.10, −0.05 on the right side of this relational expression. , -0.03, or even around -0.01, it can be understood that the formula indicates a safe area where the film will not peel.

On the other hand, it can be said that the reworkability is better as the peel adhesion strength before moisture absorption is lower. Therefore, for example, when 3.00 is added to the right side of the above relational expression, the relation in which the inequality sign is reversed is satisfied, and the above relational expression is also satisfied at the same time, that is, in the range of the following relational expression, the moisture absorption film expands. The balance between safety against peeling and reworkability can be achieved, and it can be said that this is particularly effective in the present invention.
0.0011X ² + 0.058X−0.26 ≦ Y ≦ 0.0011X ² + 0.058X + 2.74 (where 0 <Y ≦ 5.00)

  In the above formula, 3.00 is added, which is 0.50, 1.00, 1.50, 2.00, 2.50, 3.50, 4.00, or 4.50. There may be.

<Hygroscopic film>
A moisture absorption film has a moisture absorption layer containing a thermoplastic resin binder and a chemical adsorbent. The moisture-absorbing film can be provided with a skin layer for the purpose of adjusting the moisture absorption rate and / or for improving the handleability during production or use of the hygroscopic laminate.

  If the volume expansion coefficient after moisture absorption of the moisture absorbent film is too large, it becomes necessary to adhere very strongly, and thereby reworkability is lost. Therefore, it is preferably 48% or less, 40% or less, or 30% or less. . In addition, the volume expansion coefficient is too low, meaning that the amount of the chemical adsorbent is very small, and the function as a hygroscopic film is low, the volume expansion coefficient is 2% or more, 3% or more, It is preferably 5% or more, 10% or more, or 15%.

  The thickness of the hygroscopic film is, for example, 10 μm or more, 20 μm or more, or 30 μm or more, and is 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, or 80 μm or less.

  The hygroscopic laminate of the present invention can be used in electronic devices, for example, organic EL, inorganic EL, and solar cells. For example, an EL element has a TFT, a transparent electrode, an EL layer (light emitting layer), a metal electrode, and a hygroscopic laminate in this order on a transparent substrate.

  The solar cell is on the side opposite to the transparent base material on the incident light side, the power generation cell, the power generation cell and the connecting wire for connection with the outside, the sealing resin for sealing the power generation cell and the conductive wire, and the transparent base material Including a moisture-proof backsheet, the hygroscopic laminate of the present invention can be at least part of the backsheet.

<Hygroscopic film-thermoplastic resin binder>
Examples of the resin that can be used as the thermoplastic resin binder for the moisture-absorbing layer of the moisture-absorbing film include polyolefin resins, particularly low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and medium-density polyethylene (MDPE). , High density polyethylene (HDPE), polyethylene polymerized using metallocene catalyst, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer, polypropylene polymerized using metallocene catalyst, chlorinated polypropylene, Polymethylpentene, ethylene-acrylic acid copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), Tylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer (EVA), ionomer, carboxylic acid-modified polyethylene, carboxylic acid-modified polypropylene, carboxylic acid-modified ethylene-vinyl acetate copolymer, and saturated polyester, poly Also included are vinyl chloride, polystyrene, polycarbonate, polyamide, and mixtures thereof.

  Among these, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), propylene homopolymer, propylene-ethylene block copolymer, propylene- Ethylene random copolymer ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene It is preferable to use a vinyl acetate copolymer (EVA) or the like.

  The melt mass flow rate of the resin that can be used as the thermoplastic resin binder is, for example, 0.1 g / 10 min or more, 0 when measured in accordance with JIS K7210 under conditions of a temperature of 190 ° C. and a load of 21.18 N. 0.5 g / 10 min or more, 1.0 g or more, 3.0 g / 10 min or more, 10.0 g / 10 min or more, or 15.0 g / 10 min or more, 200 g / 10 min or less, 100 g / 10 min or less, 50 g / 10 min or less, Or it is 40 g / 10min or less.

<Hygroscopic film-chemical adsorbent>
The chemical adsorbent used in the present invention includes a chemical adsorption type hygroscopic agent that adsorbs moisture by chemical bonding, and expands by absorbing moisture. As a result, the hygroscopic film also expands, and a force for peeling the hygroscopic film from the substrate is generated.

  Examples of the chemical adsorbent include a chemical adsorption type hygroscopic agent. Examples of the moisture absorbent include inorganic compounds such as calcium oxide, barium oxide, magnesium oxide, lithium sulfate, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, gallium sulfate, titanium sulfate, and nickel sulfate. Can be mentioned.

  If the content of the chemical adsorbent is too low, the hygroscopicity becomes low, and if it is too high, the film expansion rate after moisture absorption becomes too high. Therefore, the chemical adsorbent is, for example, 1% by volume, 5% by volume or more, 10% by volume or more, or 20.0% by volume or more, 48.0% by volume or less, 40% by volume or less, 35. It can be made into the range of 1 volume% or less, or 30.0 volume% or less. Further, the chemical adsorbent is, for example, 1% by weight, 5% by weight or more, 10% by weight or more, 30.0% by weight or more, or 50.0% by weight or more, and 66.6% by weight or less in the moisture absorption film. Or it can be set as the range of 60.0 weight% or less.

<Hygroscopic film-skin layer>
On one or both sides of the hygroscopic layer, there is an object of suppressing the expansion of the hygroscopic film, an object of adjusting the hygroscopic rate, an object of improving the handleability during the production or use of the hygroscopic laminate, and / or a chemical adsorbent. A skin layer can be provided for the purpose of preventing direct contact with the outside.

  This skin layer can be obtained from a resin that can be used as the thermoplastic resin binder. The melt mass flow rate of the resin of the skin layer is, for example, 0.1 g / 10 min or more, 0.5 g / 10 min or more when measured according to JIS K7210 under the conditions of a temperature of 190 ° C. and a load of 21.18 N. It is 1.0 g or more, 3.0 g / 10 min or more, or 10.0 g / 10 min or more, and is 100 g / 10 min or less, 50 g / 10 min or less, or 20 g / 10 min or less.

  The thickness of the skin layer is, for example, 5 μm or more, or 8 μm or more, and is 30 μm or less, 20 μm or less, or 15 μm or less.

  The moisture-absorbing film may contain various additives such as a physical adsorbent, an anti-blocking agent, a lubricant, an antioxidant, and an antistatic agent as long as they do not depart from the gist of the present invention and can be formed into a film.

<Hygroscopic film-production method>
The moisture-absorbing film can be produced by kneading the thermoplastic resin binder and chemical adsorbent described above to obtain a resin composition and forming it into a film. For kneading, for example, a batch kneader such as a kneader, a Banbury mixer, a mixing roll conical mixer, or a continuous kneader such as a biaxial kneader is used. In this case, kneading can be performed at a temperature of 100 ° C. or higher, 120 ° C. or higher, or 140 ° C. or higher, and 220 ° C. or lower, 200 ° C. or lower, or 180 ° C. or lower, depending on the material to be used.

  The kneaded resin composition can be formed into a film to obtain a moisture absorbing film. For example, the kneaded resin composition can be formed into a film by press molding, inflation method, T-die method, extrusion molding such as coextrusion or injection molding.

  You may obtain the moisture absorption film which has a skin layer by shape | molding the resin of a skin layer with said resin composition by a multilayer inflation method. Alternatively, the moisture absorbing film may be obtained by coextruding the resin of the skin layer on both surfaces or one surface of the film of the resin composition, or laminating the film to be the skin layer by thermocompression bonding or the like.

<Base material>
The substrate is not particularly limited, and substrates of any material can be used. For example, it may be an inorganic material or an organic material. Examples of inorganic materials include inorganic oxide materials and metal materials.

  Specifically, examples of the inorganic oxide include glass and ceramic. Moreover, iron, aluminum, copper, and those alloys (for example, stainless steel etc.) can be mentioned as a metal material. Examples of the organic material include polymer materials such as ABS resin, vinyl chloride resin, epoxy resin, polyamide, polypropylene, polycarbonate, acrylic resin, polyester (polyethylene terephthalate (PET), and the like).

  These substrates may be surface-treated in order to adjust the peel adhesion strength. For example, a PET film having a release layer made of a silicone resin, a fluorine resin, or the like may be used.

<Adhesive layer>
The hygroscopic film is bonded to the substrate by the adhesive layer. Such an adhesive layer can be constituted by an applied adhesive, an adhesive tape having an adhesive, or the like.

  The adhesive layer preferably gives an appropriate peel adhesion strength between the substrate and the moisture-absorbing film so that reworkability can be obtained, and the peel adhesion strength may be 5.00 N / 25 mm or less. preferable.

  The lower limit of the peel adhesion strength provided by the adhesive layer can be determined based on the above relational expression so that the substrate and the moisture absorbent film after moisture absorption are not peeled off. The peel adhesion strength can be adjusted depending on the type of adhesive used, the bonding conditions, the type of substrate, and the like.

  For example, adhesives that can be used in this adhesive layer include urethane adhesives, olefin resin adhesives, butyl rubber adhesives, acrylic resin adhesives, polyester resin adhesives, epoxy resin adhesives, silicones Examples thereof include resin adhesives. Among these, an acrylic adhesive is particularly preferable because no outgas is generated, hygroscopicity is low, and heat resistance is high.

<Sample preparation>
LDPE (product name: Petrocene 202R, manufactured by Tosoh Corporation, melt flow rate: 24 g / 10 min, melting point: 106 ° C.) as a thermoplastic resin binder, and calcium oxide (CaO, density: 3.35 g / cm ³ ) as a chemical adsorbent. ) Was kneaded so that the calcium oxide content was 4 to 40% by volume to obtain a hygroscopic composition. The kneading was performed using a lab plast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

  LLDPE (product name: Evolue SP2520, manufactured by Prime Polymer Co., Ltd., melt flow rate: 1.9 g / 10 min, melting point: 122 ° C.) was used as the resin for the skin layer to be bonded to the front and back of the moisture absorption layer. The above hygroscopic composition and skin layer resin were formed into a film by using a T-die for co-extrusion of the three layers so that the thickness of the hygroscopic layer was 40 μm and the skin layers of the front and back surfaces were 10 μm, respectively. .

  An acrylic adhesive was applied to the moisture-absorbing film with a wire bar, and this was aged at 40 ° C. for 7 days to obtain a moisture-absorbing film with an adhesive. And the hygroscopic laminated body was obtained by bonding this to various base materials. Here, Table 1 and Table 2 show the types of acrylic adhesive and base material of each sample.

"Evaluation methods"
1. Measurement of peel adhesion strength After a moisture-absorbing film with an adhesive is cut to a width of 25 mm and bonded to various base materials, in accordance with the 180 ° peeling method described in JIS K 6854-2, using a tensile tester, The adhesion strength between the substrate and the hygroscopic film was measured (N = 3). The gripping movement speed was 100 mm / min.

2. Appearance inspection for peeling / exfoliation After adhering a moisture-absorbing film with adhesive (25 mm x 50 mm) to the substrate and leaving it in an environment at a temperature of 60 ° C. and a relative humidity of 90% for at least 24 hours to saturate and absorb the moisture-absorbing film The appearance of this was inspected. The case where peeling can be confirmed from the appearance was rated as x, and the case where peeling could not be confirmed was marked as ◯.

3. Volume expansion coefficient measurement of film Pass through the center of a 10cm square moisture-absorbing film, draw from the end to the end of the film, two perpendicular lines drawn from each other, the center of four sections separated by the reference line, and the reference line The thickness of a total of five points of the intersection of was measured. The average thickness of the measured value of the thickness of the hygroscopic film was obtained by the number average of these five thicknesses, and the volume of the hygroscopic film before moisture absorption was calculated using the vertical and horizontal dimensions of the film. The moisture-absorbing film whose volume was measured was allowed to stand for 24 hours or more in an environment at a temperature of 60 ° C. and a relative humidity of 90%, and after saturated moisture absorption, the average thickness was determined in the same manner, and the length of the marked line was measured. The volume of the moisture absorption film after saturated moisture absorption was calculated. And the volume expansion coefficient before and behind moisture absorption was computed from the ratio (N = 5).

"Evaluation results"
Table 1 shows the results of evaluating the various hygroscopic laminates shown in Table 1 prepared by changing the base material and the adhesive within the range where the peel adhesion strength is 10 N / 25 mm or less, by the evaluation method described above. I write.

  As can be seen from Table 1, depending on the volume expansion coefficient due to moisture absorption of the moisture-absorbing film, it can be seen that the peel adhesion strength required to prevent peeling after moisture absorption differs. For example, when the hygroscopic film expands as much as 56% after absorbing moisture, a peel adhesive strength of 6.4 N / 25 mm is required between the hygroscopic film before moisture absorption and the substrate, but the volume expansion is 3 In the case of a very small percentage, 0.033 N / 25 mm is sufficient as the peel adhesion strength.

  FIG. 2 shows the relationship between the volume expansion coefficient after moisture absorption created from the results of the above test example and the peel adhesion strength between the moisture absorbing film and the substrate before moisture absorption that does not cause peeling after moisture absorption. Here, a quadratic approximate expression is created from the relationship between the lowest peel adhesion strength at which peeling did not occur after moisture absorption and the deposition expansion rate.

  FIG. 3 shows the relationship between the content of calcium oxide (chemical adsorbent) and the expansion rate of the moisture-absorbing film containing it.

DESCRIPTION OF SYMBOLS 1 Base material 2 Hygroscopic film 21 Inner skin layer 22 Hygroscopic layer 23 Outer skin layer 3 Adhesive layer 10 Hygroscopic laminated body

Claims (6)

A substrate, a hygroscopic film, a hygroscopic laminate having an adhesive layer between the substrate and the hygroscopic film,
The moisture-absorbing film has a moisture-absorbing layer containing a thermoplastic resin binder and a chemical adsorbent which are polyolefin resins, and the moisture-absorbing film has a skin layer containing a polyolefin-based resin on one side or both sides of the moisture-absorbing layer. The adhesive layer is bonded to the moisture absorbing layer of the moisture absorbing film or the skin layer,
Hygroscopicity satisfying the following relationship, the peel adhesion strength Y (N / 25 mm) between the base material and the hygroscopic film before the start of moisture absorption uses the volume expansion coefficient X (%) of the hygroscopic film after moisture absorption. Laminate:
Y ≧ 0.0011X ² + 0.058X−0.26 (where 0 <Y ≦ 5.00)   The said chemical adsorbent is selected from the group consisting of calcium oxide, barium oxide, magnesium oxide, lithium sulfate, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, gallium sulfate, titanium sulfate and nickel sulfate. The hygroscopic laminate as described.   The hygroscopic laminate according to claim 1, wherein the substrate is an inorganic material or an organic material.   The hygroscopic laminate according to any one of claims 1 to 3, wherein the hygroscopic film has a skin layer containing a polyolefin resin on one side or both sides of the hygroscopic layer.   The electronic device containing the hygroscopic laminated body as described in any one of Claims 1-4.   The electronic device according to claim 5, which is an organic EL module, an inorganic EL module, or a solar battery.

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