JP5663828B2 - Water absorbent resin composition - Google Patents
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- JP5663828B2 JP5663828B2 JP2008288709A JP2008288709A JP5663828B2 JP 5663828 B2 JP5663828 B2 JP 5663828B2 JP 2008288709 A JP2008288709 A JP 2008288709A JP 2008288709 A JP2008288709 A JP 2008288709A JP 5663828 B2 JP5663828 B2 JP 5663828B2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 163
- 239000011342 resin composition Substances 0.000 title claims description 54
- 239000002250 absorbent Substances 0.000 title description 46
- 230000002745 absorbent Effects 0.000 title description 31
- 238000010521 absorption reaction Methods 0.000 claims description 68
- 229920005992 thermoplastic resin Polymers 0.000 claims description 43
- 239000011358 absorbing material Substances 0.000 claims description 36
- 229920005989 resin Polymers 0.000 claims description 33
- 239000011347 resin Substances 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 28
- 230000035699 permeability Effects 0.000 claims description 23
- 239000011159 matrix material Substances 0.000 claims description 16
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims description 14
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 13
- 230000008961 swelling Effects 0.000 claims description 13
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 claims description 12
- 230000004888 barrier function Effects 0.000 claims description 10
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 9
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 9
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 8
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 8
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 7
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 7
- 239000010419 fine particle Substances 0.000 claims description 7
- 239000004715 ethylene vinyl alcohol Substances 0.000 claims description 6
- -1 polyethylene terephthalate Polymers 0.000 claims description 6
- 229920002292 Nylon 6 Polymers 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 48
- 239000000047 product Substances 0.000 description 13
- 238000000034 method Methods 0.000 description 12
- 238000011156 evaluation Methods 0.000 description 11
- 238000002156 mixing Methods 0.000 description 9
- 229920000089 Cyclic olefin copolymer Polymers 0.000 description 8
- 239000004713 Cyclic olefin copolymer Substances 0.000 description 8
- 239000012790 adhesive layer Substances 0.000 description 7
- 239000000499 gel Substances 0.000 description 7
- 229920001684 low density polyethylene Polymers 0.000 description 6
- 239000004702 low-density polyethylene Substances 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 5
- 239000012153 distilled water Substances 0.000 description 5
- 235000013305 food Nutrition 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000004806 packaging method and process Methods 0.000 description 5
- 239000008188 pellet Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000003814 drug Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000000071 blow moulding Methods 0.000 description 3
- 239000002274 desiccant Substances 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 230000000007 visual effect Effects 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 239000004840 adhesive resin Substances 0.000 description 2
- 229920006223 adhesive resin Polymers 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 101150059062 apln gene Proteins 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229920006122 polyamide resin Polymers 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920013716 polyethylene resin Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000007666 vacuum forming Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Landscapes
- Laminated Bodies (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Description
本発明は、吸水性樹脂組成物に関し、より詳細には、吸水速度が高いと共に、吸水量も大きく、効率よく水分を吸収することが可能な吸水性樹脂組成物に関する。 The present invention relates to a water-absorbing resin composition, and more particularly to a water-absorbing resin composition that has a high water absorption rate and a large water absorption amount and can absorb water efficiently.
水分の影響を受けやすい、食品、医薬品、精密機器、電子部品等を包装する包装容器においては、包装容器内の水分を効率よく吸収することが必要であり、このような内容品の保存には、容器内の湿気を除去するために、シリカゲル、ゼオライト等の乾燥剤を充填した小袋を上記製品と一緒に封入することが一般に行われている。
しかしながら、このような別体の乾燥剤を封入するのは、内容品によっては、封入操作が煩雑であると共に容器容積の減少により製品の収納に支障があったり、或いは乾燥剤を充填した小袋の破損により、内容品に影響を与えるおそれがある。
For packaging containers that are sensitive to moisture, such as food, pharmaceuticals, precision equipment, and electronic parts, it is necessary to efficiently absorb the moisture in the packaging container. In order to remove moisture in the container, a sachet filled with a desiccant such as silica gel or zeolite is generally enclosed together with the product.
However, such a separate desiccant may be sealed depending on the contents, because the sealing operation is complicated and the container capacity is reduced due to a decrease in the container volume, or the sachet filled with the desiccant is used. Damage may affect contents.
このような問題を解決するものとして、容器を構成する熱可塑性樹脂中に吸湿機能を有する無機化合物を配合して成る吸湿性樹脂組成物から成る吸湿層を有する吸湿容器が提案されている（特許文献１）。 As a solution to such a problem, a moisture absorbing container having a moisture absorbing layer made of a moisture absorbing resin composition formed by blending an inorganic compound having a moisture absorbing function into a thermoplastic resin constituting the container has been proposed (patent). Reference 1).
しかしながら、上記吸湿性樹脂組成物から成る吸湿層においては、吸湿材料を配合するマトリックスとして、エチレン系樹脂や、αオレフィン−エチレン共重合体、或いはエチレン−環状オレフィン共重合体等のポリオレフィン樹脂が用いられており、これらの熱可塑性樹脂は、水分透過性の低いものであるため、水分が吸湿材料に到達するまでに時間がかかり、水分の吸収速度の点で未だ十分満足するものではなかった。
また吸湿材料として無機化合物を用いると、マトリックス樹脂と吸湿材料との間の剥離によりボイドが発生し、吸湿性能の低下や、透明性等の外観不良、或いは機械的物性の低下という問題を生じる場合がある。
However, in the hygroscopic layer comprising the hygroscopic resin composition, a polyolefin resin such as an ethylene resin, an α-olefin-ethylene copolymer, or an ethylene-cycloolefin copolymer is used as a matrix for blending the hygroscopic material. Since these thermoplastic resins have low moisture permeability, it takes time for moisture to reach the moisture-absorbing material, and it has not been sufficiently satisfactory in terms of moisture absorption rate.
In addition, when an inorganic compound is used as the hygroscopic material, voids are generated due to peeling between the matrix resin and the hygroscopic material, resulting in problems such as poor hygroscopic performance, poor appearance such as transparency, or poor mechanical properties. There is.
従って本発明の目的は、水分を効率よく吸収することができると共に、吸水（吸湿）性能に優れた吸水性樹脂組成物を提供することである。
本発明の他の目的は、外部からの吸湿を有効に防止することができると共に、内部の水分を効率よく吸収し、水分の影響を受けやすい食品、医薬品等の製品を保存性よく収納可能な多層構造体を提供することである。
Accordingly, an object of the present invention is to provide a water-absorbing resin composition that can absorb moisture efficiently and has excellent water absorption (moisture absorption) performance.
Another object of the present invention is to effectively prevent moisture absorption from the outside, efficiently absorb moisture inside, and store products such as foods and pharmaceuticals that are easily affected by moisture with good storage stability. It is to provide a multilayer structure.
本発明によれば、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０〜５００である熱可塑性樹脂（マトリックス樹脂）と吸水性材料からなる吸水性樹脂組成物からなる層、及び、その外層側に形成された５ｇ／ｍ ２ ・ｄａｙ（４０℃ ９０％ＲＨ２５μｍ）以下の水蒸気バリア材で構成される多層構造体であって、前記熱可塑性樹脂が、酢酸ビニル含有量が２０〜５０ｗｔ％の範囲にあるエチレン−酢酸ビニル共重合体（ＥＶＡ）、エチレンビニルアルコール共重合体（ＥＶＯＨ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリエチレンテレフタレート（ＰＥＴ）、ナイロン６の少なくとも１種から成り、前記吸水性材料が、水膨潤度が１０以下且つ平均粒径が５μｍ以下の架橋構造を有するアクリル系微粒子から成り、吸水性材料が熱可塑性樹脂に対し、１〜５０ｗｔ％の量で含有されていることを特徴とする多層構造体が提供される。
Ａ：４０℃ ９０％ＲＨ 厚さ２５μｍにおける熱可塑性樹脂の水蒸気透過度
Ｂ：２３℃ ５０％ＲＨ ２４時間浸漬における熱可塑性樹脂の吸水率
According to the present invention, a layer made of a water-absorbent resin composition comprising a thermoplastic resin (matrix resin) and a water-absorbing material, wherein the product A × B of the water vapor permeability A and the water absorption B is 10 to 500 , and A multilayer structure composed of a water vapor barrier material of 5 g / m 2 · day (40 ° C. 90% RH 25 μm) or less formed on the outer layer side , wherein the thermoplastic resin has a vinyl acetate content of 20 to 50 wt% It consists of at least one of ethylene-vinyl acetate copolymer (EVA), ethylene vinyl alcohol copolymer (EVOH), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and nylon 6 in the range of The material is made of acrylic fine particles having a crosslinked structure having a water swelling degree of 10 or less and an average particle diameter of 5 μm or less, and the water-absorbing material is a thermoplastic resin. Contrast, the multilayer structure, characterized in that it is contained in an amount of 1 to 50 wt% is provided.
A: 40 ° C. 90% RH Water vapor permeability of thermoplastic resin at thickness 25 μm B: 23 ° C. 50% RH Water absorption of thermoplastic resin after 24 hours immersion
本発明の多層構造体においては、
１．熱可塑性樹脂の水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが２０〜５００であること、
２．吸水性材料が親水基を有するアクリル系微粒子であること、
が好適である。
尚、本発明において、「吸水性」は「吸湿性」を含み、「水分」は「水蒸気」を含むものとして使用する。
In the multilayer structure of the present invention,
1. The product A × B of the water vapor permeability A and the water absorption B of the thermoplastic resin is 20 to 500,
2. The water-absorbing material is an acrylic fine particle having a hydrophilic group,
Is preferred .
In the present invention, “water absorption” includes “hygroscopicity”, and “water” includes “water vapor”.
本発明の多層構造体に用いられる吸水性樹脂組成物（以下、本発明の吸水性樹脂組成物と呼ぶことがある。）によれば、マトリックス樹脂の水蒸気透過度と吸水率の積が上記範囲にあることにより、水分を効率よく吸水性材料に到達させることができ、吸水速度及び吸水量を顕著に向上することができる。
本発明の吸水性樹脂組成物から成る層を有する多層構造体においては、構造体内部の水分を速やかに除去することが可能であり、湿気により影響を受けやすい食品や医薬品等を収納する容器や包装として好適に使用することができる。
According to the water absorbent resin composition used in the multilayer structure of the present invention (hereinafter sometimes referred to as the water absorbent resin composition of the present invention) , the product of the water vapor permeability and the water absorption rate of the matrix resin is in the above range. By being in this, water | moisture content can be made to reach | attain a water absorbing material efficiently, and a water absorption speed | rate and a water absorption amount can be improved notably.
In the multilayer structure having a layer made of the water-absorbent resin composition of the present invention, it is possible to quickly remove moisture inside the structure, and containers for storing foods and pharmaceuticals that are easily affected by moisture, It can be suitably used as a package.
本発明の吸水性樹脂組成物においては、吸水性材料を配合するマトリックス樹脂として、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０〜５００、特に２０〜５００の範囲にあるものを使用することが重要な特徴である。
前述したように、従来の吸水性樹脂組成物においては、吸水性材料を配合する熱可塑性樹脂が吸水性の低いものであったことから、吸水性材料に水分が到達するまでに時間がかかり、結果として十分水分を吸収することができない、という問題を有している。
本発明においては、マトリックス樹脂が高い水蒸気透過度を有することにより、水分のマトリックス樹脂に対する拡散速度を高めて、水分がマトリックス樹脂を透過して吸水性材料に到達し得る速度及び吸水量を増加させると共に、マトリックス樹脂自体が吸水性を有することにより、短時間でより多くの水分を吸収することが可能となるのである。
In the water-absorbent resin composition of the present invention, as the matrix resin for blending the water-absorbing material, a product having a product A × B of the water vapor permeability A and the water absorption B in the range of 10 to 500, particularly 20 to 500 is used. It is an important feature.
As described above, in the conventional water-absorbing resin composition, since the thermoplastic resin blended with the water-absorbing material has a low water absorption, it takes time until moisture reaches the water-absorbing material, As a result, there is a problem that moisture cannot be sufficiently absorbed.
In the present invention, since the matrix resin has a high water vapor permeability, the diffusion rate of moisture into the matrix resin is increased, and the rate at which moisture can permeate the matrix resin and reach the water-absorbing material is increased. At the same time, since the matrix resin itself has water absorbency, it becomes possible to absorb more water in a short time.
本発明の吸水性樹脂組成物において、上記水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０〜５００の範囲、特に２０〜５００の範囲にあることにより、上述した効果が奏されることは後述する実施例の結果から明らかである。
すなわち、熱可塑性樹脂中に吸水性材料を配合している場合であっても、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０未満である樹脂組成物（比較例２）においては、同一の吸水性材料を同量配合した樹脂組成物（実施例１）に比して半分以下の吸水量しかなく、十分な吸水性が得られていない。これに対して、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０以上である樹脂組成物（実施例１〜９）においては、優れた吸水性が得られている。特に、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが２０以上であり、吸水性材料として非膨張性架橋有機を配合して成る樹脂組成物（実施例１〜４、６、９）においては、吸水材料及び樹脂組成物全体の吸水量が多く、優れた吸水性能を有していることが明らかである。
尚、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが５００よりも大きい熱可塑性樹脂は、水蒸気透過度Ａ及び吸水率Ｂが大きすぎるため、吸水による機械的強度の劣化が激しく、実用に供することが困難である。
In the water absorbent resin composition of the present invention, when the product A × B of the water vapor permeability A and the water absorption B is in the range of 10 to 500, particularly in the range of 20 to 500, the above-described effects are exhibited. This is clear from the results of Examples described later.
That is, even when the water-absorbing material is blended in the thermoplastic resin, in the resin composition (Comparative Example 2) in which the product A × B of the water vapor permeability A and the water absorption B is less than 10, Compared to a resin composition (Example 1) containing the same amount of the same water-absorbing material, the amount of water absorption is only half or less, and sufficient water absorption is not obtained. On the other hand, in the resin compositions (Examples 1 to 9) in which the product A × B of the water vapor permeability A and the water absorption B is 10 or more, excellent water absorption is obtained. In particular, in the resin composition (Examples 1-4, 6, 9) in which the product A × B of the water vapor permeability A and the water absorption B is 20 or more, and a non-intumescent crosslinked organic is blended as a water-absorbing material. It is clear that the water absorption material and the resin composition as a whole have a large amount of water absorption and have excellent water absorption performance.
A thermoplastic resin having a product A × B of water vapor permeability A and water absorption B larger than 500 has a water vapor permeability A and water absorption B that are too large. It is difficult to provide.
（熱可塑性樹脂）
本発明の吸水性樹脂組成物において、マトリックスとして使用し得る熱可塑性樹脂としては、上述したように、水蒸気透過度Ａと吸水率Ｂの積Ａ×Ｂが１０〜５００、好ましくは２０〜５００、より好ましくは２０〜４００の範囲にある熱可塑性樹脂である。
尚、本発明における熱可塑性樹脂の水蒸気透過度Ａは、４０℃、９０％ＲＨ条件下で測定した、２５μｍ厚みの熱可塑性樹脂フィルムの水蒸気透過度（ｇ／ｍ２・ｄａｙ）であり、一方、熱可塑性樹脂の吸水率Ｂは、熱可塑性樹脂ペレットを２３℃、５０％ＲＨの条件下で２４時間蒸留水に浸漬させた前後の重量差を浸漬前の重量で除した値である。
(Thermoplastic resin)
In the water-absorbent resin composition of the present invention, as the thermoplastic resin that can be used as the matrix, as described above, the product A × B of the water vapor permeability A and the water absorption B is 10 to 500, preferably 20 to 500, More preferably, it is a thermoplastic resin in the range of 20 to 400.
The water vapor permeability A of the thermoplastic resin in the present invention is the water vapor permeability (g / m 2 · day) of a 25 μm-thick thermoplastic resin film measured under the conditions of 40 ° C. and 90% RH, The water absorption B of the thermoplastic resin is a value obtained by dividing the weight difference before and after immersing the thermoplastic resin pellets in distilled water for 24 hours at 23 ° C. and 50% RH by the weight before immersion.
このような熱可塑性樹脂としては、これに限定されないが、酢酸ビニル含有量が２０〜５０ｗｔ％の範囲にあるエチレン−酢酸ビニル共重合体（ＥＶＡ）、エチレンビニルアルコール共重合体（ＥＶＯＨ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリエチレンテレフタレート（ＰＥＴ）等を挙げることができ、中でも特に酢酸ビニル含有量が２０〜５０ｗｔ％の範囲にあるエチレン−酢酸ビニル共重合体、エチレンビニルアルコール共重合体を好適に使用することができる。また、上述した樹脂を２種類以上ブレンドして使用することができる。 Such thermoplastic resins include, but are not limited to, ethylene-vinyl acetate copolymer (EVA), ethylene vinyl alcohol copolymer (EVOH), poly (vinyl acetate) content in the range of 20-50 wt% vinyl acetate. Examples thereof include methyl methacrylate (PMMA) and polyethylene terephthalate (PET). Among them, ethylene-vinyl acetate copolymers and ethylene vinyl alcohol copolymers having a vinyl acetate content in the range of 20 to 50 wt% are particularly preferable. Can be used. Further, two or more kinds of the above-described resins can be blended and used.
（吸水性材料）
本発明の吸水性樹脂組成物に用いる吸水性材料としては、ポリアクリル酸、或いはポリアクリル酸ナトリウム等のポリα，β不飽和カルボン酸を挙げることができる。また、上述した吸水材料を２種類以上ブレンドし、使用することができる。
(Water-absorbing material)
The absorbent material used in the water absorbent resin composition of the present invention, mention may be made of Po Riakuriru acid, or poly α such as sodium polyacrylate, the β-unsaturated carboxylic acid. Further, two or more kinds of the water-absorbing materials described above can be blended and used.
本発明に用いる吸水性材料としては、機械的物性及び衛生性の点から、親水基を有する有機系化合物であることが好ましく、中でも有機系化合物が架橋構造を有することが好ましい。吸水による溶解が生じないため食品等に用いる場合、衛生的に安全である。
さらに、架橋構造を有すると共に、水膨潤度が１０以下、特に５以下であることが好ましい。水膨潤度が１０より大きい吸水性材料では、樹脂に配合した際、吸水性材料の周りを取り囲むマトリックス樹脂種によっては、吸水に伴う膨潤が阻害され、性能を発現できないことがある。これに対して、水膨潤度が１０以下の吸水性材料では、樹脂種に制限されることなく性能を発現することができる。これは、構造内の自由体積が水を取り込むサイトになるためと考えられ、架橋密度や架橋間距離、親水基数等により吸水量を制御できると推測される。吸水性材料としては、非膨潤性架橋アクリル系微粒子を挙げることができる。前記微粒子の平均粒径は、１０μｍ以下、特に５μｍ以下であることが好ましい。
尚、水膨潤度は、後述する吸水性材料を室温（２５℃）の条件下で２４時間蒸留水に浸漬させた前後の体積比で測定される。
The water-absorbing material used in the present invention is preferably an organic compound having a hydrophilic group from the viewpoint of mechanical properties and hygiene, and among them, the organic compound preferably has a crosslinked structure. Since it does not dissolve due to water absorption, it is hygienic and safe when used in foods.
Further, it preferably has a crosslinked structure and has a water swelling degree of 10 or less, particularly 5 or less. In a water-absorbing material having a degree of water swelling greater than 10, depending on the type of matrix resin surrounding the water-absorbing material, when it is added to the resin, swelling due to water absorption may be inhibited and performance may not be exhibited. On the other hand, in a water-absorbing material having a water swelling degree of 10 or less, performance can be expressed without being restricted by the resin type. This is presumably because the free volume in the structure becomes a site that takes in water, and it is speculated that the amount of water absorption can be controlled by the crosslink density, the distance between crosslinks, the number of hydrophilic groups and the like. The absorbent material may include non-swellable rack Hashia acrylic-based fine particles. The average particle size of the fine particles is preferably 10 μm or less, particularly preferably 5 μm or less.
In addition, a water swelling degree is measured by the volume ratio before and behind immersing the water absorbing material mentioned later on distilled water for 24 hours on the conditions of room temperature (25 degreeC).
（吸水性樹脂組成物）
本発明の吸水性樹脂組成物においては、上記吸水性材料をマトリックスと成る熱可塑性樹脂に対して１〜５０ｗｔ％、特に１〜３０ｗｔ％の量で配合することが好適である。上記範囲よりも少ないと、十分な吸水性能を得ることができず、一方上記範囲よりも吸水性材料の量が多いと、後述する実施例３の結果からも明らかなように、吸水性能においては優れているとしても、ブツの発生等の外観特性や成形性の点で劣るようになる。
本発明の吸水性樹脂組成物は、樹脂組成物の特性を損なわない限り、従来公知の樹脂用配合剤、例えば、充填剤、可塑剤、レベリング剤、増粘剤、減粘剤、安定剤、酸化防止剤、紫外線吸収剤等を公知の処方に従って配合することができる。
(Water absorbent resin composition)
In the water absorbent resin composition of the present invention, the water absorbent material is preferably blended in an amount of 1 to 50 wt%, particularly 1 to 30 wt% with respect to the thermoplastic resin as a matrix. If the amount is less than the above range, sufficient water absorption performance cannot be obtained. On the other hand, if the amount of the water absorbent material is larger than the above range, as is clear from the results of Example 3 described later, Even if it is excellent, it will be inferior in terms of appearance characteristics such as generation of flaws and moldability.
The water-absorbent resin composition of the present invention is a conventionally known resin compounding agent, for example, a filler, a plasticizer, a leveling agent, a thickener, a thickener, a stabilizer, as long as the properties of the resin composition are not impaired. Antioxidants, ultraviolet absorbers, and the like can be blended according to known formulations.
（多層構造体）
本発明の吸水性樹脂組成物は、それ単独でフィルム、シート等に成形し、吸水性シート、或いは吸水性フィルム等として使用することもできるが、特に他の熱可塑性樹脂から成る層との多層構造体として使用することが好ましい。
本発明においては特に、吸水性樹脂組成物からなる層とその外層側に５ｇ／ｍ２・ｄａｙ（４０℃ ９０％ＲＨ ２５μｍ）以下の水蒸気バリア材で構成される多層構造体であることが好適である。このように本発明の吸水性樹脂組成物から成る層の外側に水蒸気バリア材で構成される層が形成されていることにより、多層構造体外部に存在する水分（水蒸気）の影響を受けることなく、多層構造体内部の水分を効率的に吸収することが可能となる。
このような水蒸気バリア材としては、アルミニウム箔等の金属箔、環状オレフィン系共重合体を挙げることができるが、特に環状オレフィン系共重合体（ＣＯＣ）を好適に用いることができる。
さらに、エチレン−ビニルアルコール共重合体やポリアミド樹脂或いは酸素吸収性樹脂組成物等の酸素バリア材を有する層を中間層に設けることにより酸素バリア性を付与することができる。
(Multilayer structure)
The water-absorbent resin composition of the present invention can be formed into a film, a sheet or the like by itself and used as a water-absorbent sheet or a water-absorbent film. It is preferable to use it as a structure.
In the present invention, a multilayer structure comprising a water-absorbing resin composition layer and a water vapor barrier material of 5 g / m 2 · day (40 ° C. 90% RH 25 μm) or less on the outer layer side is preferable. It is. As described above, since the layer composed of the water vapor barrier material is formed outside the layer made of the water absorbent resin composition of the present invention, it is not affected by moisture (water vapor) existing outside the multilayer structure. In addition, it becomes possible to efficiently absorb moisture inside the multilayer structure.
Examples of such a water vapor barrier material include metal foils such as aluminum foil, and cyclic olefin copolymers, and particularly, cyclic olefin copolymers (COC) can be suitably used.
Furthermore, oxygen barrier properties can be imparted by providing a layer having an oxygen barrier material such as an ethylene-vinyl alcohol copolymer, a polyamide resin, or an oxygen-absorbing resin composition in the intermediate layer.
吸水性樹脂組成物から成る層は、多層構造体の最内層とすることもできるが、内容物が食品や医薬品等の場合には、他の熱可塑性樹脂から成る最内層を設けることが衛生的観点から望ましい。本発明の吸水性樹脂組成物から成る層の内面側に設ける層は、速やかに本発明の吸水性樹脂組成物から成る層に水蒸気を到達させるために、比較的水蒸気透過率が高いものであることが好ましく、好適には、酢酸ビニル含有量が２０〜５０ｗｔ％の範囲にあるエチレン−酢酸ビニル共重合体等を挙げることができる。 The layer made of the water-absorbing resin composition can be the innermost layer of the multilayer structure, but if the contents are food, medicine, etc., it is hygienic to provide the innermost layer made of another thermoplastic resin. Desirable from a viewpoint. The layer provided on the inner surface side of the layer made of the water-absorbent resin composition of the present invention has a relatively high water vapor permeability so that water vapor can quickly reach the layer made of the water-absorbent resin composition of the present invention. Preferably, an ethylene-vinyl acetate copolymer having a vinyl acetate content in the range of 20 to 50 wt% can be mentioned.
本発明の多層構造体において、各層の厚みに特に制限はないが、本発明の吸水性樹脂組成物から成る層は、１〜１０００μｍ、特に５〜５００μｍの範囲にあるのが好適である。また水蒸気バリア材から成る外層は、１〜５００μｍ、特に１〜１００μｍの範囲にあるのが好ましく、内層を設ける場合には、１〜１００μｍ、特に１〜５０μｍの範囲にあるのが好ましい。
本発明の多層構造体は、これに限定されるものではないが、従来公知の製法によって、フィルム 、シート、カップ、トレイ 、包装袋、容器蓋、ボトル等の成形体として成形され、吸湿性に優れた包装材として使用することができる。
本発明の多層構造体において、フィルム或いはシートは、予め各層を別途形成し、熱接着などの方法により積層することもできるし、従来公知の接着剤を用いて積層することも勿論できる。また共射出、共押出等の従来公知の積層体の方法により成形することもできる。カップ、トレイ等は、上記方法により得られたシートを真空成形、圧空成形、張出成形、プラグアシスト成形等に付することにより成形することができる。
またパウチ等の包装袋は、種々の形状に従来公知の製法により成形することができ、ボトルは、従来公知の押出機から押し出した中空パリソンをダイレクトブロー成形、或いは射出成形によって得たプリフォームを二軸延伸ブロー成形することにより成形することができる。
In the multilayer structure of the present invention, the thickness of each layer is not particularly limited, but the layer made of the water absorbent resin composition of the present invention is preferably in the range of 1 to 1000 μm, particularly 5 to 500 μm. The outer layer made of the water vapor barrier material is preferably in the range of 1 to 500 μm, particularly 1 to 100 μm. When the inner layer is provided, it is preferably in the range of 1 to 100 μm, particularly 1 to 50 μm.
The multilayer structure of the present invention is not limited to this, but is formed into a molded body such as a film, a sheet, a cup, a tray, a packaging bag, a container lid, and a bottle by a conventionally known manufacturing method, and is hygroscopic. It can be used as an excellent packaging material.
In the multilayer structure of the present invention, the film or sheet may be formed by separately forming each layer in advance and laminated by a method such as thermal bonding, or of course, using a conventionally known adhesive. Moreover, it can also shape | mold by the methods of conventionally well-known laminates, such as co-injection and co-extrusion. Cups, trays and the like can be formed by subjecting the sheet obtained by the above method to vacuum forming, pressure forming, bulging forming, plug assist forming and the like.
In addition, packaging bags such as pouches can be formed into various shapes by a conventionally known manufacturing method, and bottles are formed by direct blow molding or injection molding of a hollow parison extruded from a conventionally known extruder. It can shape | mold by carrying out biaxial stretch blow molding.
１．［熱可塑性樹脂(マトリックス樹脂)］
（水蒸気透過度Ａの測定)
５０ｔホットプレス（庄司鉄工製）により２００℃で熱可塑性樹脂の加熱溶融を繰り返し、厚み約１５０μmのシートを作製した。水蒸気透過測定装置（ＰＥＲＭＡＴＲＡＮ−Ｗ ３／３０：ＭＯＣＯＮ社製）により得られたシートの４０℃ ９０％ＲＨにおける水蒸気透過度を測定し、２５μm厚に換算して、熱可塑性樹脂の水蒸気透過度とした。
（吸水率Ｂの測定）
熱可塑性樹脂ペレット２．０ｇを２３℃ ５０％ＲＨの条件下で２４時間蒸留水に浸漬させた。その後、ペレット表面についた水をふき取り、電子天秤で秤量し、下記計算式より吸水率を求めた。
1. [Thermoplastic resin (matrix resin)]
(Measurement of water vapor permeability A)
A thermoplastic resin was repeatedly heated and melted at 200 ° C. by a 50-ton hot press (manufactured by Shoji Iron Works) to produce a sheet having a thickness of about 150 μm. The water vapor transmission rate at 40 ° C. and 90% RH of a sheet obtained by a water vapor transmission measurement device (PERMATRAN-W 3/30: manufactured by MOCON) was measured, converted into a thickness of 25 μm, and the water vapor transmission rate of the thermoplastic resin did.
(Measurement of water absorption B)
2.0 g of thermoplastic resin pellets were immersed in distilled water for 24 hours under conditions of 23 ° C. and 50% RH. Thereafter, the water attached to the pellet surface was wiped off, weighed with an electronic balance, and the water absorption was determined from the following formula.
２．［吸水性材料］
(水膨潤度の測定)
メスシリンダーに有機系吸水性材料０．５ｇと蒸留水１００ｍｌを入れ、室温（２５℃）で２４時間静置した。その後、有機系吸水性材料の体積をメスシリンダーの目盛りから読み取り、これを吸水後の体積とした。また、吸水前の体積は嵩密度（ＪＩＳ Ｚ２５０４に準拠）より仕込み量０．５ｇを換算した値を用いた。吸水前後の体積変化を水膨潤度とし、下記計算式より算出した。
2. [Water-absorbing material]
(Measurement of water swelling)
An organic water-absorbing material (0.5 g) and distilled water (100 ml) were placed in a graduated cylinder and allowed to stand at room temperature (25 ° C.) for 24 hours. Thereafter, the volume of the organic water-absorbing material was read from the scale of the graduated cylinder, and this was taken as the volume after water absorption. Moreover, the volume before water absorption used the value which converted 0.5g preparation amount from the bulk density (based on JISZ2504). The volume change before and after water absorption was taken as the degree of water swelling, and was calculated from the following formula.
３．［吸水性樹脂組成物］
（作製方法）
出口部分にストランドダイを装着した二軸押出機（スクリュー径φ２０ Ｌ／Ｄ＝３２．５ＵＬＴＮａｎｏ０５−２０ＡＧ：テクノベル社製）により、押出温度２００℃ スクリュー回転数１００ｒｐｍで真空ベントを引きながら熱可塑性樹脂を溶融混練した。同時に粉体フィーダーを用いて、押出機ホッパー下より吸水性材料を配合した。このとき熱可塑性樹脂に対し１０ｗｔ％になるように、配合量を調整した。
3. [Water-absorbing resin composition]
(Production method)
With a twin-screw extruder (screw diameter φ20 L / D = 32.5 ULT Nano 05-20AG: manufactured by Technobel) with a strand die attached to the outlet portion, thermoplastic resin was drawn while pulling a vacuum vent at an extrusion temperature of 200 ° C. and a screw rotation speed of 100 rpm. Melt kneaded. At the same time, a water-absorbing material was blended from under the extruder hopper using a powder feeder. At this time, the blending amount was adjusted so as to be 10 wt% with respect to the thermoplastic resin.
(混練時の目視評価)
吸水性樹脂組成物を作製する際の目視評価として、押し出されたストランドの外観やベントアップの有無を確認し、特に問題ないものを○、ストランド中にブツが発生し、ゲルの分散が不十分なものを△、樹脂圧の増加等によるベントアップ等により作製できなかったものを×とした。
(Visual evaluation during kneading)
As a visual evaluation when preparing a water-absorbent resin composition, check the appearance of the extruded strand and the presence or absence of vent-up, ○ if there is no particular problem, puncture occurs in the strand, gel dispersion is insufficient △, and those that could not be produced by venting up due to an increase in resin pressure, etc.
(吸水量評価)
上記方法で得られた吸水性樹脂組成物ペレット２．０ｇを２３℃ ５０％ＲＨの条件下で２４時間蒸留水に浸漬させた。その後、ペレット表面の水分を拭き取り電子天秤で重量増加分を求め、これを吸水量とした。吸水量が１５ｍｇ以上のものを○、１５ｍｇ未満のものを×として評価した。また同様な方法で、熱可塑性樹脂のみの吸水量を測定し、吸水性樹脂組成物の重量と熱可塑性樹脂の重量の差分を吸水性材料の吸水量とした。
(Water absorption evaluation)
2.0 g of the water-absorbent resin composition pellets obtained by the above method was immersed in distilled water for 24 hours under conditions of 23 ° C. and 50% RH. Thereafter, the moisture on the pellet surface was wiped off and the weight increase was determined with an electronic balance, and this was taken as the amount of water absorption. The water absorption amount of 15 mg or more was evaluated as ◯, and the water absorption amount of less than 15 mg was evaluated as ×. Further, the water absorption amount of only the thermoplastic resin was measured by the same method, and the difference between the weight of the water absorbent resin composition and the weight of the thermoplastic resin was taken as the water absorption amount of the water absorbent material.
［多層構造体］
（多層ボトルの作製）
上記方法により作製した吸水性樹脂組成物、水蒸気バリア材として環状オレフィンコポリマー樹脂（アペルＡＰＬ８００８Ｔ：三井化学（株））、低密度ポリエチレン樹脂（スミカセンＦ１０８−２：住友化学(株)）、接着性樹脂（アドマーＳＦ７３０：三井化学(株)）を用いて、ダイレクトブロー成形機により多層構造体を作製した。成形温度は２００℃、シェル径１５ｍｍ、コア１３ｍｍを用い、広口ボトル（口径４４ｍｍ、内容積１２５ｃｃ)を作製した。
層構成は、外層側より低密度ポリエチレン樹脂層（２５０μm）／接着層（５μm）／環状オレフィンコポリマー樹脂層（１５μm）／接着層（５μm）／吸水性樹脂組成物層（５０μm)の４種５層、または外層側より低密度ポリエチレン樹脂層（２５０μm）／接着層（５μm）／環状オレフィンコポリマー樹脂層（１５μm）／接着層（５μm）／吸水性樹脂組成物層（５０μm)／接着層（５μｍ）／低密度ポリエチレン樹脂層（１０μm）の４種７層である。
（多層フィルムの作製）
上記方法により作製した吸水性樹脂組成物、水蒸気バリア材として環状オレフィンコポリマー樹脂（アペルＡＰＬ８００８Ｔ：三井化学（株））、低密度ポリエチレン樹脂（スミカセンＦ１０８−２：住友化学(株)）、接着性樹脂（アドマーＳＦ７３０：三井化学(株)）を用いて、多層フィルム成形機により成形温度２５０℃で多層フィルムを作製した。
層構成は、外層側より低密度ポリエチレン樹脂層（５０μm）／接着層（５μm）／環状オレフィンコポリマー樹脂層（２０μm）／接着層（５μm）／吸水性樹脂組成物層（５０μm)／低密度ポリエチレン樹脂層（２０μm）の４種６層である。
[Multilayer structure]
(Production of multi-layer bottles)
Water-absorbing resin composition produced by the above method, cyclic olefin copolymer resin (Apel APL8008T: Mitsui Chemicals) as a water vapor barrier material, low density polyethylene resin (Sumikasen F108-2: Sumitomo Chemical Co., Ltd.), adhesive resin (Admer SF730: Mitsui Chemicals, Inc.) was used to produce a multilayer structure with a direct blow molding machine. Using a molding temperature of 200 ° C., a shell diameter of 15 mm, and a core of 13 mm, a wide-mouth bottle (44 mm diameter, 125 cc internal volume) was produced.
There are four types of layer configurations: low density polyethylene resin layer (250 μm) / adhesive layer (5 μm) / cyclic olefin copolymer resin layer (15 μm) / adhesive layer (5 μm) / water absorbent resin composition layer (50 μm) from the outer layer side. Low-density polyethylene resin layer (250 μm) / adhesive layer (5 μm) / cyclic olefin copolymer resin layer (15 μm) / adhesive layer (5 μm) / water absorbent resin composition layer (50 μm) / adhesive layer (5 μm) ) / Low density polyethylene resin layer (10 μm).
(Production of multilayer film)
Water-absorbing resin composition produced by the above method, cyclic olefin copolymer resin (Apel APL8008T: Mitsui Chemicals) as a water vapor barrier material, low density polyethylene resin (Sumikasen F108-2: Sumitomo Chemical Co., Ltd.), adhesive resin (Admer SF730: Mitsui Chemicals, Inc.) was used to produce a multilayer film at a molding temperature of 250 ° C. using a multilayer film molding machine.
The layer structure is lower density polyethylene resin layer (50 μm) / adhesive layer (5 μm) / cyclic olefin copolymer resin layer (20 μm) / adhesive layer (5 μm) / water absorbent resin composition layer (50 μm) / low density polyethylene from the outer layer side. There are 4 types and 6 layers of resin layers (20 μm).
（吸水性評価）
前記作製した多層ボトル内にワイヤレス式温湿度計（ハイグロクロン：ＫＮラボラトリーズ製）を入れ、２３℃ ６０％ＲＨの雰囲気下において、アルミ／ポリエチレンで積層した蓋材で容器口部をヒートシールした。多層フィルムでは、内容積が１５０ｍｌになるように包装袋を作製し、ボトル同様に上記雰囲気下で端部をヒートシールした。２４時間静置後、容器内部の湿度が２０％ＲＨ以下になっているものを○、２０％ＲＨより高いものを×とした。
(Water absorption evaluation)
A wireless thermometer / hygrometer (Higlocron: manufactured by KN Laboratories) was placed in the produced multilayer bottle, and the container mouth was heat sealed with a lid material laminated with aluminum / polyethylene in an atmosphere of 23 ° C. and 60% RH. For the multilayer film, a packaging bag was prepared so that the internal volume was 150 ml, and the end portion was heat-sealed under the above atmosphere in the same manner as the bottle. After leaving still for 24 hours, the one in which the humidity inside the container was 20% RH or less was rated as ◯, and the one higher than 20% RH was marked as x.
（実施例１）
熱可塑性樹脂として水蒸気透過度５２０ｇ／ｍ２・ｄａｙ、吸水率０．０５％、酢酸ビニル含有量が２０ｗｔ％であるエチレン−酢酸ビニル共重合体樹脂（ＥＶＡ２０％、ウルトラセンＥＶＡ６３８：東ソー(株)）、吸水性材料として水膨潤度１．２（嵩密度０．２８ｇ／ｃｍ３）のアクリル系微粒子である非膨潤性架橋有機ゲル（タフチックＨＵ：東洋紡(株)）を用い、上記作製方法により吸水性樹脂組成物を作製し、混練時の目視評価および吸水性評価を行なった。ブツの発生はなく、均一にゲルが分散しており、ベントアップ等の問題なく作製することができた。吸水性材料は２０ｍｇ程度吸水しており、上記方法により作製した４種５層の多層構造体の吸水性評価において、容器内部の湿度が２０％ＲＨ以下であった。
Example 1
Ethylene-vinyl acetate copolymer resin (EVA 20%, Ultrasen EVA 638: Tosoh Corporation) having a water vapor transmission rate of 520 g / m 2 · day, a water absorption of 0.05%, and a vinyl acetate content of 20 wt% as a thermoplastic resin ), A non-swellable crosslinked organic gel (Tuffic HU: Toyobo Co., Ltd.), which is an acrylic fine particle having a water swelling degree of 1.2 (bulk density 0.28 g / cm 3 ) as a water-absorbing material, A water-absorbent resin composition was prepared, and visual evaluation and water-absorption evaluation during kneading were performed. There was no fluffing, the gel was uniformly dispersed, and it could be produced without problems such as vent-up. The water-absorbing material absorbs about 20 mg of water, and in the water absorption evaluation of the four-kind five-layer multilayer structure produced by the above method, the humidity inside the container was 20% RH or less.
（実施例２）
吸水性材料の配合量を５０ｗｔ％にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。特に問題なく作製することができ、吸水性材料の配合量増加により吸水性能が向上していた。また上記方法により作製した４種５層の多層構造体の吸水性評価において、容器内部の湿度が２０％ＲＨ以下であった。
(Example 2)
A water absorbent resin composition was prepared in the same manner as in Example 1 except that the blending amount of the water absorbent material was 50 wt%. It was possible to produce without any problem, and the water absorption performance was improved by increasing the blending amount of the water absorbing material. Moreover, in the water absorption evaluation of the multilayer structure of 4 types and 5 layers produced by the above method, the humidity inside the container was 20% RH or less.
（実施例３）
吸水性材料の配合量を６０ｗｔ％にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。ストランド中にブツが発生し、ゲルの分散が不十分であったが、作製することができた。実施例２同様に、配合量増加により性能が向上し、４種７層で作製した多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
Example 3
A water absorbent resin composition was prepared in the same manner as in Example 1 except that the blending amount of the water absorbent material was changed to 60 wt%. There were spots in the strands, and the gel was insufficiently dispersed, but could be produced. As in Example 2, the performance was improved by increasing the blending amount, and the humidity inside the container was 20% RH or less in the multilayer structure produced with four types and seven layers.
（実施例４）
熱可塑性樹脂を３０ｇ／ｍ２・ｄａｙ、吸水率３．５％、エチレン含有量が３２ｍｏｌ％であるエチレン−ビニルアルコール共重合体樹脂（ＥＶＯＨ、Ｆ１７１Ｂ：(株)クラレ）にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。特に問題なく作製することができ、ＥＶＯＨ、吸水性材料ともに吸水しており、特にＥＶＯＨの吸水量が多かった。また上記方法により作製した４種７層の多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
Example 4
Implementation was performed except that the thermoplastic resin was an ethylene-vinyl alcohol copolymer resin (EVOH, F171B: Kuraray Co., Ltd.) having 30 g / m 2 · day, a water absorption of 3.5%, and an ethylene content of 32 mol%. As in Example 1, a water absorbent resin composition was prepared. It was possible to produce without any problem, and both EVOH and the water-absorbing material absorbed water, and EVOH absorbed particularly a large amount of water. Moreover, in the 4 types 7 layers multilayer structure produced by the said method, the humidity inside a container was 20% RH or less.
（実施例５）
吸水性材料として水膨潤度１．０（嵩密度３．０ｇ／ｃｍ３）のゼオライト３Ａ（純正化学(株)）を用いた以外は実施例１と同様に吸水性樹脂組成物を作製した。特に問題なく作製することができ、実施例１との比較において非膨潤性架橋有機ゲルより性能が劣るが吸水性を示した。また４種５層で作製した多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
(Example 5)
A water absorbent resin composition was prepared in the same manner as in Example 1 except that zeolite 3A (Pure Chemical Co., Ltd.) having a water swelling degree of 1.0 (bulk density: 3.0 g / cm 3 ) was used as the water absorbent material. It was possible to produce without any problem, and in comparison with Example 1, the performance was inferior to that of the non-swellable crosslinked organic gel, but it showed water absorption. Moreover, in the multilayer structure produced by four types and five layers, the humidity inside the container was 20% RH or less.
（実施例６）
熱可塑性樹脂を２００ｇ／ｍ２・ｄａｙ、吸水率２．０％であるポリアミド樹脂（Ｎｙｌｏｎ６、ＵＢＥナイロン１０２２Ｂ：宇部興産製）にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。特に問題なく作製することができ、Ｎｙｌｏｎ６、吸水性材料ともに吸水しており、４種７層の多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
(Example 6)
A water-absorbent resin composition was prepared in the same manner as in Example 1 except that the thermoplastic resin was a polyamide resin (Nylon 6, UBE nylon 1022B: manufactured by Ube Industries) having a water absorption of 2.0% at 200 g / m 2 · day. Produced. It can be produced without any particular problem, and both Nylon 6 and the water-absorbing material absorb water, and the humidity inside the container is 20% RH or less in the multilayer structure of 4 types and 7 layers.
（実施例７）
熱可塑性樹脂を４０ｇ／ｍ２・ｄａｙ、吸水率０．３％であるポリメタクリル酸メチル樹脂（ＰＭＭＡ：和光純薬）にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。特に問題なく作製することができ、ＰＭＭＡ、吸水性材料ともに吸水しており、４種７層の多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
(Example 7)
A water-absorbing resin composition was prepared in the same manner as in Example 1 except that the thermoplastic resin was a polymethyl methacrylate resin (PMMA: Wako Pure Chemical Industries) having a water absorption of 0.3% at 40 g / m 2 · day. did. The PMMA and the water-absorbing material were both water-absorbing, and the humidity inside the container was 20% RH or less in the multilayer structure of 4 types and 7 layers.
（実施例８）
熱可塑性樹脂として水蒸気透過度２２ｇ／ｍ２・ｄａｙ、吸水率０．５％であるポリエチレンテレフタレート樹脂（ＰＥＴ、ＲＴ５４３ＣＴＨＰ：日本ユニペット(株)）、吸水性材料として水膨潤度１００．０（嵩密度０．６５ｇ／ｃｍ３）のアクリル酸系膨潤性有機ゲル（サンフレッシュＳＴ−５００ＭＰＳ：三洋化成(株)）、押出温度２８０℃とし、上記方法により吸水性樹脂組成物を作製した。特に問題なく作製することができ、吸水性材料の吸水はほとんどなく、ＰＥＴの吸水が多かった。この原因としては、膨潤性有機ゲルは吸水と同時に膨潤する材料であるため、樹脂組成物のようなマトリックス中に分散している系では、マトリックスが吸水性材料の膨潤を阻害しているためと推察される。多層構造体の吸水性評価では、４種５層の多層構造体において、容器内部の湿度が２０％ＲＨ以下であった。
(Example 8)
Polyethylene terephthalate resin (PET, RT543CTHP: Nihon Unipet Co., Ltd.) having a water vapor transmission rate of 22 g / m 2 · day and a water absorption of 0.5% as a thermoplastic resin, and a water swell of 100.0 (bulk) as a water absorbent material A water-absorbing resin composition was prepared by the above-described method, with an acrylic acid-based swellable organic gel (Sunfresh ST-500MPS: Sanyo Chemical Co., Ltd.) having a density of 0.65 g / cm 3 ) and an extrusion temperature of 280 ° C. The water-absorbing material could hardly be produced, and there was almost no water absorption of the water-absorbing material, and there was much water absorption of PET. This is because the swellable organic gel is a material that swells simultaneously with water absorption, and in a system dispersed in a matrix such as a resin composition, the matrix inhibits the swelling of the water absorbent material. Inferred. In the water absorption evaluation of the multilayer structure, the humidity inside the container was 20% RH or less in the multilayer structure of 4 types and 5 layers.
（実施例９）
実施例１で作製した吸水性樹脂組成物を用いて、前記方法により多層フィルムを作製した。吸水性評価では、容器内部の湿度が２０％ＲＨ以下であった。
Example 9
Using the water absorbent resin composition produced in Example 1, a multilayer film was produced by the above method. In the water absorption evaluation, the humidity inside the container was 20% RH or less.
（比較例１）
吸水性材料を配合しなかった以外は、実施例１と同様に吸水性樹脂組成物を作製した。
(Comparative Example 1)
A water absorbent resin composition was prepared in the same manner as in Example 1 except that the water absorbent material was not blended.
（比較例２）
熱可塑性樹脂を８０ｇ／ｍ２・ｄａｙ、吸水率０．０５％、酢酸ビニル含有量が１０ｗｔ％であるエチレン−酢酸ビニル共重合体樹脂（ＥＶＡ１０％、ウルトラセンＥＶＡ５４１：東ソー(株)）にした以外は、実施例１と同様に、吸水性樹脂組成物を作製した。特に問題もなく作製することができたが、吸水量が少なく、作製した４種５層の多層構造体においても容器内部の湿度低下がほとんど認められなかった。この原因としては、熱可塑性樹脂の水蒸気透過度が低いため、吸水性材料の吸水性能が十分発現できていないと考えられる。
(Comparative Example 2)
An ethylene-vinyl acetate copolymer resin (EVA 10%, Ultrasen EVA 541: Tosoh Corporation) having a thermoplastic resin of 80 g / m 2 · day, a water absorption of 0.05%, and a vinyl acetate content of 10 wt% was used. Except for this, a water-absorbent resin composition was prepared in the same manner as in Example 1. Although it could be produced without any particular problem, the amount of water absorption was small, and even in the produced four-kind five-layer multilayer structure, a decrease in humidity inside the container was hardly observed. As this cause, since the water vapor permeability of a thermoplastic resin is low, it is thought that the water absorption performance of a water absorbing material is not fully expressed.
実施例１〜９（但し、実施例５及び８は参考例）、比較例１〜２の結果を表１にまとめた。表１の結果から明らかなように、熱可塑性樹脂の水蒸気透過度および吸水率、吸水性材料の種類や配合量、水膨潤度の違いにより吸水性評価で相違が見られた。 Examples 1 to 9 (however, Examples 5 and 8 are reference examples) Table 1 summarizes the results of Comparative Examples 1 and 2. As is clear from the results in Table 1, there were differences in water absorption evaluation due to differences in water vapor permeability and water absorption of thermoplastic resins, types and blending amounts of water absorbent materials, and water swelling.
Claims (3)
前記熱可塑性樹脂が、酢酸ビニル含有量が２０〜５０ｗｔ％の範囲にあるエチレン−酢酸ビニル共重合体（ＥＶＡ）、エチレンビニルアルコール共重合体（ＥＶＯＨ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリエチレンテレフタレート（ＰＥＴ）、ナイロン６の少なくとも１種から成り、
前記吸水性材料が、水膨潤度が１０以下且つ平均粒径が５μｍ以下の架橋構造を有するアクリル系微粒子から成り、
吸水性材料が熱可塑性樹脂に対し、１〜５０ｗｔ％の量で含有されていることを特徴とする多層構造体。
Ａ：４０℃ ９０％ＲＨ 厚さ２５μｍにおける熱可塑性樹脂の水蒸気透過度
Ｂ：２３℃ ５０％ＲＨ ２４時間浸漬における熱可塑性樹脂の吸水率 A product made of a water-absorbing resin composition comprising a thermoplastic resin (matrix resin) and a water-absorbing material having a product A × B of water vapor permeability A and water absorption B of 10 to 500 , and formed on the outer layer side. A multilayer structure composed of a water vapor barrier material of 5 g / m 2 · day (40 ° C. 90% RH 25 μm) or less,
The thermoplastic resin is an ethylene-vinyl acetate copolymer (EVA), ethylene vinyl alcohol copolymer (EVOH), polymethyl methacrylate (PMMA), polyethylene terephthalate (vinyl acetate content in the range of 20-50 wt%) PET), consisting of at least one of nylon 6,
The water-absorbing material consists of acrylic fine particles having a crosslinked structure with a water swelling degree of 10 or less and an average particle diameter of 5 μm or less,
A multilayer structure comprising a water-absorbing material in an amount of 1 to 50 wt% with respect to a thermoplastic resin.
A: 40 ° C. 90% RH Water vapor permeability of thermoplastic resin at thickness 25 μm B: 23 ° C. 50% RH Water absorption of thermoplastic resin after 24 hours immersion
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