JP2008279662A - Multilayered bottle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylene multilayered bottle with improved low temperature impact resistance and good in heat resistance, transparency at filling time at a high temperature and slip properties. <P>SOLUTION: The multilayered bottle 1 is formed into a multilayered structure by blow molding. 2 shows a cap. In a propylene-type resin composing the outermost layer of the multilayered bottle 1, 1-20 wt.% of a styrene-ethylene butylene-styrene block copolymer with a styrene content of ≤12 wt.% and an organic lubricant of ≤2,000 ppm are incorporated. It is preferable that a thermoplastic resin composing the innermost layer is the same as the resin composing the outermost layer. The thermoplastic resin composing the outermost layer consisting of a mixture of a propylene-type resin and an SEBS elastomer has a tensile elastic modulus (JIS K7113) at -30°C of ≤16,000 kg/cm<SP>2</SP>, preferably ≤15,000 kg/cm<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer container excellent in rigidity, transparency, surface glossiness, heat resistance and low-temperature impact resistance, and particularly excellent in transparency and slipperiness during filling of high-temperature contents.

  Conventionally, plastic bottles having a multilayer structure have been used as food packaging bottles. The multilayer bottle is configured as a multilayer structure in which a barrier resin such as ethylene-vinyl alcohol copolymer (EVOH) having a high oxygen barrier property is disposed as an intermediate layer from the viewpoint of storage stability of the content. Accordingly, the resin used for the inner and outer layers is selected. For example, low density polyethylene is used when soft and squeeze is required, and polypropylene is used when heat resistance and rigidity are required.

  However, in general, polypropylene has low impact resistance at low temperatures, and the bottle is easily damaged by dropping. For this reason, the drop strength at low temperatures has been improved by various methods. For example, Patent Document 1 discloses blow molding comprising a resin in which 5 to 20 parts by weight of a linear low density polyethylene and 2 to 20 parts by weight of an olefin-based soft elastomer are blended with a polypropylene resin in order to improve low temperature impact resistance. Made bottles are disclosed. Soft resin such as linear polyethylene or olefin elastomer added to polypropylene can improve the low temperature impact resistance depending on its density, while the rigidity of the container and the transparency at high temperature filling There was a problem that it was excessively lowered and the surface of the container became soft and easily damaged.

  For this reason, it has been proposed to use a styrene-based elastomer as a modified resin having low temperature impact resistance and transparency added to polypropylene. For example, Patent Document 2 or 3 discloses a multilayer container in which impact resistance is improved without reducing transparency by blending a hydrogenated polymer of a styrene-butadiene block copolymer with a homopolymer or block copolymer of propylene. Is disclosed.

However, in applications where the contents are filled with liquid or semi-liquid seasonings such as sauce, sauce, ketchup, dressing, the contents are injected into the bottle at a high temperature (eg, 70 ° C.) at the time of filling. And then stored at low temperature. A conventional styrene-based elastomer is not sufficient in low-temperature impact resistance, and transparency and slipperiness on a filling line are poor due to high-temperature filling.
JP-A-61-98756 JP-A-5-270570 JP 11-290422 A

  Accordingly, an object of the present invention is to develop a multilayer bottle which improves low temperature impact resistance and has good heat resistance, transparency at the time of high temperature filling, and good sliding properties.

  The inventors of the present invention conducted intensive research to solve the above-mentioned problems. As a result, the thermoplastic resin constituting the outermost layer of the multilayer bottle was changed to a propylene / α-olefin random copolymer and a styrene / ethylene / butylene / styrene block copolymer (SEBS). Elastomer) and a styrene content of 12 wt%, preferably 10 wt% or less, and an organic lubricant of 2000 ppm or less is added to the thermoplastic resin constituting the outermost layer. It has been found that a bottle having good impact properties, transparency at the time of high-temperature filling and slipperiness can be obtained. The present invention has been made based on such findings.

That is, this invention provides the multilayer bottle made from blow molding which was excellent in the low temperature impact resistance and transparency which consist of a structure of following 1) -5) description.
1) The outermost layer is composed of a propylene-based resin containing 1 to 20 wt% of SEBS elastomer having a styrene content of 12 wt% or less. Thereby, the bottle excellent in low temperature impact resistance and transparency can be obtained.
2) A SEBS elastomer having a styrene content of 10 wt% or less is used. Thereby, low temperature impact resistance and transparency can be improved.
3) The transparency of the bottle body at normal temperature and high temperature filling is a total light transmittance of 60% or more.
4) An organic lubricant of 2000 ppm or less is added to the outermost layer with respect to the thermoplastic resin. Thereby, while maintaining transparency also in the filling line of a high temperature content, it is slippery and can prevent blocking and damage due to contact between bottles.
5) The content filled in the bottle is a liquid or semi-liquid food filled at a high temperature.

  According to the present invention, in a multi-layer bottle having an inner and outer layer made of a polypropylene resin, the low temperature impact resistance is improved, transparency and slipperiness at the time of high temperature filling are excellent, scratch resistance, glossiness, heat resistance, and rigidity. Can also get a well-balanced one.

Hereinafter, the present invention will be described in detail. The multilayer bottle 1 according to the present invention has low temperature impact resistance, and the bottle is formed into a multilayer structure by blow molding. 2 is a cap. The thermoplastic resin constituting the outermost layer is made of a mixed material of 80-99 wt% polypropylene resin and 1-20 wt%, preferably 8-15 wt% SEBS elastomer. Furthermore, it is preferable to use the same thermoplastic resin constituting the innermost layer as the resin constituting the outermost layer. As the propylene-based resin, a propylene / α-olefin random copolymer is used. To the propylene-based resin, 1000 to 3000 ppm of an antioxidant is added, and 2000 ppm or less of an organic lubricant is added. As the organic lubricant, fatty acid amides are preferably used. As the SEBS elastomer, a styrene-ethylene-butylene-styrene block copolymer having a styrene content of 12 wt%, preferably 10 wt% or less is used. The thermoplastic resin composed of a mixture of propylene-based resin and SEBS elastomer constituting the outermost layer has a tensile elastic modulus (JIS K7113) at minus 30 ° C. of 16000 kg / cm ^2, preferably 15000 kg / cm ² or less.

  By using a SEBS elastomer having a low styrene content, impact resistance at low temperatures can be improved and transparency at high temperatures and normal temperatures can be increased. That is, when the styrene content of the SEBS elastomer exceeds 12 wt%, the impact resistance at low temperature is lowered, and transparency at high temperature and normal temperature cannot be achieved at the same time. In addition, when elastomer or low density soft resin is added to improve impact resistance, the bottle surface is particularly damaged due to contact between bottles on the line, and the glossiness or transparency tends to decrease. Cause clogging. Therefore, it is conceivable to add a lubricant to improve the slipperiness. However, increasing the amount of the lubricant added to improve the slipperiness is not preferable because it causes a decrease in transparency and bleeding. Therefore, by making the styrene content of the SEBS elastomer added to the propylene-based resin 12 wt% or less and the blending amount of the organic lubricant 2000 ppm or less, impact resistance at low temperature and transparency and slipperiness at high temperature can be obtained. An excellent multilayer bottle can be obtained.

The intermediate layer having an oxygen barrier property has an oxygen permeability at 30 ° C.-60% RH of 10 (cc · 20 μm / m ² · day · atm) or less, preferably 1.0 (cc · 20 μm / m ² · (day · atm) or less thermoplastic resin having a melting point of 180 ° C. or higher, preferably 185 ° C. or higher, more preferably 190 ° C. or higher. As the resin having an oxygen barrier property, an ethylene-vinyl alcohol copolymer (EVOH) is suitable. Generally, an ethylene-vinyl acetate copolymer having an ethylene content of 60 mol% or less is saponified to a saponification degree of 90% or more. Used.

  Furthermore, an adhesive layer or a recycled resin layer can be appropriately provided between the outermost layer and the innermost layer and the intermediate layer having oxygen barrier properties. As the adhesive resin, an olefin copolymer having a carboxyl group is preferably used, and maleic anhydride-modified polypropylene and the like are particularly suitable.

A multilayer bottle composed of the multilayer structure of each example was formed, and the performance of the multilayer bottle was evaluated by the following measurement method and standard. The multilayer bottle has a capacity of 500 ml formed by blow molding, has a total film thickness of 400 to 600 μm in the body portion, and has the following layer structure.
3 types and 5 layers: From outer layer side, outermost layer / adhesive layer / intermediate layer / adhesive layer / innermost layer The film thickness ratio of each layer is 42% for outermost layer, 1.5% for adhesive layer, 4% for intermediate layer, 50 for innermost layer %Met.

[Example 1]
A blow molded multilayer bottle having the above layer structure was formed. As the resin constituting the outer layer and the inner layer, a thermoplastic resin in which 90 wt% of propylene / α-olefin random copolymer was blended with 10 wt% of styrene-ethylene / butylene-styrene block copolymer was used. A styrene-ethylene / butylene-styrene block copolymer having a styrene content of 10 wt% was used. Further, 1000 ppm of a known fatty acid amide type lubricant as a lubricant was added to the thermoplastic resin constituting the inner and outer layers. Furthermore, an ethylene-vinyl alcohol copolymer was used as a resin constituting the intermediate layer. As the ethylene-vinyl alcohol copolymer, Soarnol DC3212B manufactured by Nippon Synthetic Chemical Co., Ltd. having an ethylene content of 32 mol% and a saponification degree of 99% was used. Further, a modified polyolefin resin was used as a resin constituting the adhesive layer. As the modified polyolefin resin, Modic P512V manufactured by Mitsubishi Chemical Corporation was used. The slipperiness on the line was also good, and no bottle clogging occurred on the line, and there was no decrease in transparency or glossiness due to scratches.

[Example 2]
A blow molded multilayer bottle having the above layer structure was formed. The same procedure as in Example 1 was performed except that a thermoplastic resin in which 95 wt% of propylene / α-olefin random copolymer was blended with 5 wt% of styrene / ethylene / butylene / styrene block copolymer was used as the resin constituting the outer layer and the inner layer.

[Example 3]
A blow molded multilayer bottle having the above layer structure was formed. Example 1 except that the styrene-ethylene butylene-styrene block copolymer in which the resin constituting the inner and outer layers is blended with the propylene / α-olefin random copolymer as the resin constituting each layer has a styrene content of 12 wt%. Same as above. A styrene-ethylene-butylene-styrene block copolymer having a styrene content of 12 wt% was used.

[Example 4]
A blow molded multilayer bottle having the above layer structure was formed. Example 3 was the same as Example 3 except that a thermoplastic resin in which 5 wt% of styrene-ethylene / butylene-styrene block copolymer was blended with 95 wt% of propylene / α-olefin random copolymer was used as the resin constituting the outer layer and the inner layer.

[Example 5]
A blow molded multilayer bottle having the above layer structure was formed. The thermoplastic resin constituting the inner and outer layers was the same as Example 1 except that 500 ppm of the known fatty acid amide-based lubricant used in Example 1 was added as a lubricant. The slipperiness on the line was poor and bottle clogging occurred on the line. In addition, transparency and glossiness due to scratches were observed.

[Comparative Example 1]
Example 1 except that the styrene-ethylene / butylene-styrene block copolymer having a styrene content of 18 wt% is blended with a propylene / α-olefin random copolymer as a resin constituting each layer. Same as above. As the styrene-ethylene-butylene-styrene block copolymer, one having a styrene content of 18 wt% was used.

[Comparative Example 2]
As a resin constituting the outer layer and the inner layer, a thermoplastic resin in which 10 wt% of ethylene propylene rubber (EPR) is blended with 90 wt% of propylene / α-olefin random copolymer is used, and as a lubricant for the thermoplastic resin constituting the inner and outer layers, Example 1 The same procedure as in Example 1 was performed except that 500 ppm of the known fatty acid amide-based lubricant used in 1 was added.

[Comparative Example 3]
As a resin constituting the outer layer and the inner layer, a thermoplastic resin containing 90 wt% of a propylene / α-olefin random copolymer and 10 wt% of a linear ultra-low density ethylene / α-olefin copolymer polymerized using a metallocene catalyst is used. The thermoplastic resin constituting the inner and outer layers was the same as in Example 1 except that 500 ppm of the known fatty acid amide lubricant used in Example 1 was added as a lubricant.

[Evaluation methods]
1) Low temperature impact resistance Each multilayer bottle formed by the above blow molding is filled with about 500 cc of water and stored at minus 5 ° C, dropped 10 times from a height of 1.5 m onto the concrete surface. confirmed. Table 1 shows the number of broken bottles in 10 multilayer bottles. The number of damaged pieces was evaluated as 0, excellent up to 2, good up to 4, good up to 5 or more.
2) Transparency (total light transmittance)
A test piece cut out from the body of each multilayer bottle formed by the blow molding was measured for total light transmittance in accordance with JIS K7361-1. Table 1 shows the numerical values obtained by converting the total light transmittance at each thickness to 500 μm for comparison because the test pieces cut out from the bottle body have variations in thickness. A total light transmittance of 60% or more was evaluated as good, and a value less than 60% was evaluated as impossible.

In Examples 1 to 3, the number of dropped bottles was up to two, and the evaluation was excellent or good, and the transparency was a good evaluation with a value of 60% or more at both normal temperature and high temperature.
In Example 4, four dropped bottles were damaged and evaluated as good, and the transparency was evaluated as good at high temperatures, but at room temperature, the evaluation was 50%, and was not possible. At the same time and at high temperatures, transparency could not be satisfied at the same time.
In Example 5, as in Example 1, the low-temperature impact resistance was excellent and the transparency was good, but the slipperiness was poor and bottle clogging occurred in the line. In addition, scratches due to collisions between bottles occurred during the filling process, packaging process, etc. in the line, and transparency and glossiness were reduced.
In Comparative Example 1, the low-temperature impact resistance was evaluated as good, and the transparency at room temperature was inferior. Further, in Comparative Examples 2 and 3, the evaluation of the low temperature impact resistance was impossible, and the transparency was evaluated as inferior in transparency due to white turbidity at high temperatures.

It is explanatory drawing which shows the multilayer bottle which concerns on one embodiment of this invention.

Explanation of symbols

1 Multi-layer bottle 2 Cap

Claims (5)

  In the multilayer bottle formed by blow molding, the thermoplastic resin constituting the outermost layer contains 1 to 20 wt% of styrene-ethylene butylene-styrene block copolymer (SEBS elastomer) with respect to 80 to 99 wt% of polypropylene resin. And the styrene content of the said SEBS elastomer is 12 wt% or less, The multilayer bottle characterized by the above-mentioned.   The multilayer bottle according to claim 1, wherein the SEBS elastomer has a styrene content of 10 wt% or less.   The multi-layer bottle has transparency, and the total light transmittance (JIS K7361-1) of the bottle body at normal temperature and when high temperature contents are filled is 60% or more. Multi-layer bottle.   The multilayer bottle according to claim 1, wherein an organic lubricant of 2000 ppm or less is added to the outermost layer with respect to the thermoplastic resin.   The multilayer bottle according to claim 1, wherein the food is filled with liquid or semi-liquid food.

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