JP3688430B2 - Propylene resin film and method for producing the same - Google Patents

Description

【００３５】
表１において、「ＨＳＢＲ」は、水添スチレン−ブタジエンランダム共重合体であり、「ＳＥＰＳ」はスチレン−エチレンプロピレン−スチレンブロック共重合体であり、「ＳＩＰＳ」は水添スチレン−イソプレン−スチレンブロック共重合体である。
得られた実施例１〜４及び比較例１〜４のフィルムについて、ヘイズ、弾性率、触感、及びシール強度を以下のようにして測定した。測定結果を表２に示す。
【００３６】
ヘイズ
ＪＩＳ Ｋ ７１０５に準じて測定した。
弾性率
ＪＩＳ Ｋ ７１３３に準じて測定した。
【００３７】
触感評価
以下の基準で、得られたフィルムの風合いとしわの発生しやすさを触感として評価した。
４：柔らかく良好でしわの発生が少ない
３：柔らかく良好だが、しわの発生が起こりやすい
２：やや硬い
１：硬く、しゃりしゃり感が残る
【００３８】
シール強度
得られたフィルム２枚を、内層が対向するように重ね合わせ、インパルス溶断シール機を用いて、圧力４ｋｇ／ｃｍ² 、圧締時間２秒、インパルス時間１秒の条件で、シールした後、これをシール方向に対して垂直に幅１５ｍｍで裁断し、試験片とした。この試験片を用い、ＡＳＴＭ Ｄ８８２に準じて、試験片の非シール端部同士を引っ張って、Ｔ型剥離強度を測定し、シール強度とした。
【００３９】
【表２】

【００４０】
表２に示すように、本発明に従う実施例１〜４のフィルムは、透明性に優れ、かつ包装用フィルム等として適した触感及びシール強度を有している。
【００４１】
実施例５〜８及び比較例５〜８
表３に示すポリプロピレン系樹脂（ＰＰ）及びエラストマーを用いて、外層、中間層、及び内層の３層からなるフィルムを、上記実施例１〜４と同様にして作製した。ただし、実施例５〜８及び比較例５〜８においては、外層及び内層に、表３に示す中間層に用いたエラストマーと同じエラストマーを３重量％含有させた。
【００４２】
得られたフィルムについて、ヘイズ、弾性率、触感、及びシール強度を、上記実施例と同様にして評価し、グロスを以下のようにして評価した。結果を表３に示した。
【００４３】
グロス
ＪＩＳ Ｋ ７１０５に準じて測定した。
【００４４】
【表３】

【００４５】
表３に示す結果から明らかなように、本発明に従う実施例５〜８は、包装用フィルム等として適した高い透明性及び光沢を有しており、さらには、包装用フィルム等として適した触感及びシール強度を有している。
【００４６】
【発明の効果】
請求項１に記載の発明及び請求項２に記載の発明によれば、見栄え、風合いの良いビニルフィルムや軟質塩化ビニルに匹敵する、優れた外観品質及び触感を有し、かつ良好なシール強度を有するフィルムとすることができる。
【００４７】
請求項３に記載の発明によれば、結晶の成長を抑制し、より透明で光沢のあるフィルムを得ることができる。
【図面の簡単な説明】
【図１】本発明のプロピレン系樹脂フィルムの実施例を示す断面図。
【符号の説明】
１…外層
２…中間層
３…内層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a propylene-based resin film suitable for various packaging films such as fibers, clothing, bread, noodles, and toilet paper, and a method for producing the same.
[0002]
[Prior art and problems to be solved by the invention]
As various packaging films for fibers, clothing, bread, noodles, toilet paper, etc., soft vinyl chloride to which a plasticizer has been added has been used, but these films contain harmful chlorine. There are hygiene and pollution problems, and other materials that are as transparent and glossy as or better than these films, and that are soft and textured, are being sought.
[0003]
As such a material, an olefin film has been studied. As a method for imparting flexibility suitable as a packaging film, a method using an olefin film made of a copolymer or a method using an olefin film made of a blend polymer can be considered. However, in the case of a copolymer, it is difficult to increase the α-olefin content in the copolymerization step, and the resulting film has excessive flexibility. In the case of a blend polymer, it has been technically difficult to uniformly mix both resins at a predetermined blending ratio, and there has been a problem that a product having desired mechanical strength characteristics cannot be obtained.
[0004]
In addition, when using a softer EPR (ethylene-propylene rubber), it can be softened by adding a small amount, but the dispersibility to the resin is poor, and a uniform film is obtained with a single-screw extrusion facility. It was difficult.
[0005]
In JP-A-7-290649, an outer layer made of random polypropylene, an intermediate layer made of random polypropylene containing 10 to 50% by weight of a hydrogenated diene copolymer occupying 50 to 90% of the total thickness, and random An olefin film having a degree of purity of less than 5% (in terms of 30 μm) obtained by sequentially laminating inner layers made of polypropylene has been proposed.
[0006]
However, even in the blending of such hydrogenated diene copolymers, sufficient flexibility cannot be obtained unless blending with a general-purpose polypropylene at least 10 parts by weight or more. There have been problems such as optical properties being lowered due to dispersibility problems, and quality degradation due to bleeding of low molecular weight hydrogenated diene copolymers due to blending in large quantities. In general, hydrogenated diene copolymers are often expensive and have not been put into practical use.
[0007]
Moreover, the random polypropylene resin which mix | blended the hydrogenated diene type copolymer has the problem that seal strength is inadequate.
An object of the present invention is to provide a propylene-based resin film that eliminates such conventional problems, has sufficient seal strength, and has a tactile sensation and transparency suitable as a packaging film, and a method for producing the same. There is.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is characterized in that a polypropylene resin alone or a vinyl aromatic resin is used on both surfaces of an intermediate layer composed of 97.5 to 90% by weight of a polypropylene resin and 2.5 to 10% by weight of a vinyl aromatic elastomer. A propylene-based resin film in which a surface layer composed of a mixture with an elastomer is laminated, and an elution amount at 90 ° C. or less by a cross-fractionation method of a polypropylene-based resin is 40 to 70% by weight with respect to the total weight of the resin It is a propylene-type resin film characterized by being.
[0009]
The invention according to claim 2 is the invention according to claim 1, wherein the vinyl aromatic elastomer contained in the intermediate layer and the surface layer is a hydrogenated styrene-butadiene random copolymer or a hydrogenated styrene-isoprene block copolymer. It is characterized by being a polymer.
[0010]
The invention described in claim 3 is a manufacturing method characterized in that after coextruding the resin constituting each layer from a T-die, the film is formed by cooling with a cooling roll having a surface temperature of 40 ° C. or less.
[0011]
Hereinafter, a configuration common to each invention described in claims 1 to 3 will be described as “the present invention”.
Polypropylene resin In the present invention, the polypropylene resin used for the intermediate layer and the surface layer has an elution amount of 90 ° C or less by the cross fractionation method, 40 to 70 wt% with respect to the total weight of the resin, Preferably it is 50 to 65% by weight. If the elution amount of the polypropylene resin at 90 ° C. or less is less than 40% by weight, the compatibility with the intermediate layer containing the vinyl aromatic elastomer may be insufficient, and the transparency may be lowered. On the other hand, when the amount of elution at 90 ° C. or less exceeds 70% by weight, the melting components at low temperatures increase, causing stickiness. The cross separation method will be described in detail later.
[0012]
Typical examples of the polypropylene resin used in the present invention include ternary random copolymers of propylene, ethylene, and butene, binary random copolymers of propylene and ethylene, and binary random copolymers of propylene and butene. Can be mentioned. Generally, the elution amount of 90 ° C. or less by the ternary random copolymer cross fractionation method is higher than that of the binary random copolymer. Therefore, by mixing both, it is possible to control the amount of elution according to the purpose.
[0013]
The MFR (230 ° C.) of the polypropylene resin used in the present invention is preferably 0.3 to 20 g / 10 minutes, and more preferably 2 to 10 g / 10 minutes. If the MFR is less than 0.3 g / 10 min, the fluidity may be too low and the production efficiency may decrease. Moreover, when it becomes larger than 20 g / 10 minutes, the molten resin which came out of the metal mold | draws down, and the stable manufacture may become difficult.
[0014]
Below, the cross fractionation method employ | adopted by this invention is demonstrated in detail.
Cross fractionation method First, a polypropylene resin is dissolved in o-dichlorobenzene at 140 ° C or a temperature at which the polypropylene resin completely dissolves, and then cooled at a constant rate to prepare an inert carrier prepared in advance. A thin polymer layer is formed on the surface of the film in the order of high crystallinity and molecular weight. Next, the temperature is raised continuously or stepwise, the concentration of the eluted components is detected, and the composition distribution (crystallinity distribution) is measured. This is called Temperature Rising Elution Fractionation (TREF). At the same time, the sequentially eluted components are analyzed by high temperature GPC (Size Exclusion Chromatograph; SEC) to measure the molecular weight and molecular weight distribution. In the present invention, data was measured using a cross fractionation chromatograph apparatus (manufactured by Mitsubishi Oil Chemical Co., Ltd., CFC-T150A type) equipped with both the temperature rising elution fractionation part and the high temperature GPC part as a system.
[0015]
Vinyl aromatic elastomer In the present invention, a mixed resin of a vinyl aromatic elastomer and a polypropylene resin is used for the intermediate layer. The content of the vinyl aromatic elastomer in the intermediate layer is 2.5 to 10% by weight. If the content of the vinyl aromatic elastomer is less than 2.5% by weight, the texture of the film tends to be insufficient. On the other hand, if the content exceeds 10% by weight, the flexibility of the film increases and the texture is improved, but the yield strength of the film becomes too small, the strength becomes weak, and wrinkles are likely to occur. . Therefore, the effect of improving the texture due to the addition of the vinyl aromatic elastomer cannot be obtained, and the cost increases.
[0016]
In the present invention, a mixture of a polypropylene resin and a vinyl aromatic elastomer may be used as the resin constituting the surface layer. In this case, the mixing ratio of the vinyl aromatic elastomer is preferably 10% by weight or less. When the mixing ratio of the vinyl aromatic elastomer is higher than this, the flexibility becomes too large and the yield strength becomes low, and the strength becomes weak and causes wrinkles.
[0017]
In the present invention, the gloss of the film can be improved by including a vinyl aromatic elastomer in the surface layer.
As the vinyl aromatic elastomer used in the present invention, when the vinyl aromatic compound polymer block is A and the conjugated diene polymer block is B, A- (BA) _m or (AB) _n (however, , M and n are integers greater than or equal to 1), more preferably an ABA type, an AB type block, a random copolymer, or a hydrogenated product thereof. is there.
[0018]
Examples of the vinyl aromatic compound include styrene, t-butyl styrene, α-methyl styrene, p-methyl styrene and the like, and styrene and α-methyl styrene are particularly preferable.
[0019]
Conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5 -Diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like are mentioned, and 1,3-butadiene and isoprene are particularly preferable.
[0020]
Particularly preferred vinyl aromatic elastomers include a hydrogenated styrene-butadiene random copolymer and a hydrogenated styrene-isoprene block copolymer used in the invention of claim 2.
[0021]
In the vinyl aromatic elastomer, the content of the vinyl aromatic compound unit is preferably 5 to 40% by weight, and more preferably 10 to 30% by weight. When the content of the vinyl aromatic compound unit is too small, the heat resistance becomes insufficient, and the effect of suppressing the formation of spherulites of propylene by the vinyl aromatic compound unit is reduced, which tends to be opaque. Moreover, when there is too much content of a vinyl aromatic compound unit, while elastomericity will fall, a texture will fall, it is difficult to obtain uniform dispersibility, and it exists in the tendency for transparency to also fall.
[0022]
In the present invention, the thickness of the intermediate layer is not particularly limited, but is preferably 50 to 90% of the thickness of the entire film. By making the thickness of the intermediate layer in such a range, the texture of the film can be improved.
[0023]
Film production method The propylene-based resin film of the present invention is produced at 170 to 250C, preferably using a kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a kneading roll, a brabender, or a kneader. It is obtained by heating and melting at 190 to 230 ° C., kneading, and multilayer extrusion. In particular, according to the invention described in claim 3, it is preferable to form a film by the T-die method and cool the film with a cooling roll having a surface temperature of 40 ° C. or less. Thereby, the surface can be smoothed, the formation of crystals can be suppressed, and a transparent and glossy film can be obtained.
[0024]
When the film is formed by the T-die method, the transparency of the film can be further improved by highly cooling the film. However, as the speed increases, a high degree of cooling is required. Therefore, by forming a film by a water-cooled inflation method and performing rapid cooling with water, it is possible to obtain higher transparency than the T-die method. The water-cooled inflation method may be a generally used facility, and a sufficient effect can be obtained by cooling with water of 30 ° C. or less. Therefore, in order to obtain a film having a higher degree of transparency, such downward water-cooled inflation molding is also an effective manufacturing method.
[0025]
Other additives The propylene-based resin film of the present invention has a small amount of an inorganic filler such as talc and calcium carbonate, glass fiber, carbon, and the like within the range that does not deteriorate transparency for the purpose of further modification. Reinforcing materials such as fibers, heat stabilizers, antioxidants, light stabilizers, flame retardants, plasticizers, antistatic agents, mold release agents, foaming agents, lubricants, antiblocking agents and the like can be added.
[0026]
Action According to the invention described in claim 1 and claim 2, it has excellent appearance quality and tactile sensation comparable to those of vinylon film and soft vinyl chloride, and has excellent sealing strength. Film.
[0027]
According to the invention described in claim 3, it is possible to suppress the crystal growth and obtain a more transparent and glossy film.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
In the following Examples and Comparative Examples, one outer layer 1 (thickness 9 μm), intermediate layer 2 (thickness 27 μm), and the other inner layer 3 (thickness) as shown in FIG. A film having a thickness of 9 μm) was formed by a three-layer coextrusion T-die method and cooled with a cooling roll at 20 ° C. to produce a film having a total thickness of 45 μm. The following polypropylene resins A to D were used as the polypropylene resins used for the outer layer, the intermediate layer, and the inner layer.
[0029]
Polypropylene resin A
Polypropylene-based resin material A is a ternary random copolymer of propylene / ethylene / butene, having an elution amount of 90.degree. C. or less by a cross fractionation method of 76.6% by weight, MFR of 4 g / 10 min, A binary random copolymer of ethylene having an elution amount of 90.degree. C. or lower by a cross fractionation method of 29.9% by weight and MFR of 2 g / 10 min was mixed at a mixing ratio of 50:50. The amount of elution at 90 ° C. or less by the cloth fractionation method of the obtained polypropylene resin was 52.9% by weight.
[0030]
Polypropylene resin B
As the polypropylene resin material B, the same ternary random copolymer and binary random copolymer as the resin A were used, and the mixing ratio was 80:20. The elution amount of this propylene resin at 90 ° C. or less by the cross fractionation method was 67.1% by weight.
[0031]
Polypropylene resin C
As the polypropylene resin material C, a propylene / ethylene binary random copolymer having an elution amount of 90.degree. C. or lower by a cross fractionation method of 29.2% by weight and an MFR of 2 g / 10 min was used alone.
[0032]
Polypropylene resin D
Polypropylene-based resin material D is a ternary random copolymer of propylene / ethylene / butene, with an elution amount of 90.degree. C. or less by a cross fractionation method of 76.6% by weight, and an MFR of 4 g / 10 min. It was.
[0033]
Examples 1-4 and Comparative Examples 1-4
A ratio of the vinyl aromatic elastomer shown in Table 2 as a resin for forming the outer layer and the inner layer of the above film as a resin for forming the intermediate layer using the polypropylene resin (PP) shown in Table 2 alone. The above film was produced using the resin contained in the polypropylene resin (PP). The vinyl aromatic elastomer used is an elastomer shown in Table 1.
[0034]
[Table 1]

[0035]
In Table 1, “HSBR” is a hydrogenated styrene-butadiene random copolymer, “SEPS” is a styrene-ethylenepropylene-styrene block copolymer, and “SIPS” is a hydrogenated styrene-isoprene-styrene block. It is a copolymer.
About the obtained film of Examples 1-4 and Comparative Examples 1-4, haze, an elasticity modulus, tactile sensation, and seal strength were measured as follows. The measurement results are shown in Table 2.
[0036]
The haze was measured according to JIS K 7105.
The elastic modulus was measured according to JIS K 7133.
[0037]
Evaluation of tactile sensation The texture and wrinkle susceptibility of the obtained film were evaluated as tactile sensations according to the following criteria.
4: Soft and good with little wrinkling 3: Soft and good, but easy to wrinkle 2: Slightly hard 1: Hard and crunchy [0038]
Seal strength The obtained two films are overlapped so that the inner layers face each other, and using an impulse fusing seal machine, the pressure is 4 kg / cm ² , the pressing time is 2 seconds, and the impulse time is 1 second. After sealing, this was cut at a width of 15 mm perpendicular to the sealing direction to obtain a test piece. Using this test piece, in accordance with ASTM D882, the non-sealed end portions of the test piece were pulled to measure the T-type peel strength to obtain the seal strength.
[0039]
[Table 2]

[0040]
As shown in Table 2, the films of Examples 1 to 4 according to the present invention are excellent in transparency and have tactile sensation and seal strength suitable as packaging films and the like.
[0041]
Examples 5-8 and Comparative Examples 5-8
Using the polypropylene resin (PP) and elastomer shown in Table 3, a film composed of three layers of an outer layer, an intermediate layer, and an inner layer was produced in the same manner as in Examples 1 to 4 above. However, in Examples 5 to 8 and Comparative Examples 5 to 8, 3% by weight of the same elastomer as that used for the intermediate layer shown in Table 3 was contained in the outer layer and the inner layer.
[0042]
About the obtained film, haze, elastic modulus, tactile sensation, and seal strength were evaluated in the same manner as in the above Examples, and gloss was evaluated as follows. The results are shown in Table 3.
[0043]
It was measured according to gross JIS K 7105.
[0044]
[Table 3]

[0045]
As is apparent from the results shown in Table 3, Examples 5 to 8 according to the present invention have high transparency and gloss suitable for packaging films and the like, and furthermore, tactile sensations suitable for packaging films and the like. And has a sealing strength.
[0046]
【The invention's effect】
According to the invention described in claim 1 and the invention described in claim 2, it has an excellent appearance quality and touch feeling comparable to those of a vinyl film or soft vinyl chloride which has a good appearance, and has a good sealing strength. It can be set as the film which has.
[0047]
According to the invention described in claim 3, it is possible to suppress the crystal growth and obtain a more transparent and glossy film.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a propylene-based resin film of the present invention.
[Explanation of symbols]
1 ... Outer layer 2 ... Intermediate layer 3 ... Inner layer

Claims (3)

A surface layer composed of a polypropylene resin alone or a mixture of this and a vinyl aromatic elastomer is formed on both surfaces of an intermediate layer composed of 97.5 to 90% by weight of a polypropylene resin and 2.5 to 10% by weight of a vinyl aromatic elastomer. A propylene-based resin film that is laminated, and a polypropylene-based resin is a ternary random copolymer of propylene, ethylene, and butene, a binary random copolymer of propylene and ethylene, and a binary random copolymer of propylene and butene. together comprising one or a mixture of two or more selected from polymers, characterized in that the elution amount of above 90 ℃ by cross fractionation method of that is from 40 to 70% by weight relative to the total weight of the resin A propylene-based resin film.   The propylene resin film according to claim 1, wherein the vinyl aromatic elastomer is a hydrogenated styrene-butadiene random copolymer or a hydrogenated styrene-isoprene block copolymer.   3. The production of a propylene-based resin film according to claim 1, wherein the resin constituting each layer is coextruded from a T-die and then formed by cooling with a cooling roll having a surface temperature of 40 ° C. or less. Method.

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