JP2015202895A - multilayer container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer container that maintains its own transparency while improving delamination resistance.SOLUTION: A multilayer container 10 includes inner and outer layers 15 and 16 that are made of a polyester resin, and intermediate layers 17, 17a and 17b that are arranged between the inner and outer layers 15 and 16. The intermediate layers 17a and 17b are formed by mixing nylon MXD6 with a heat-resistant amorphous polyester resin in which spiroglycol and a polyethylene terephthalate resin are copolymerized.

Description

  The present invention relates to a multilayer container.

  Conventionally, what is obtained by shape | molding a polyethylene terephthalate (henceforth "PET") is used as multilayer containers, such as drinking water, edible oil, and a shampoo. In such a multilayer container made of PET, from the viewpoint of improving the gas barrier property of the container itself, as shown in Patent Document 1, a PET / nylon MXD6 / PET three-layer structure in which a gas barrier layer is arranged in an intermediate layer or PET / Nylon MXD6 / PET / Nylon MXD6 / PET having a five-layer structure is used.

  However, in a multilayer container having a multilayer structure as shown in Patent Document 1, delamination may occur due to an impact applied to the container itself during handling or transportation. Also, delamination may occur when the container itself is repeatedly pressed by a squeeze operation. For this reason, in such a multilayer container, a method of mixing PET with nylon MXD6 is used to prevent delamination between layers. By this method, the affinity between nylon MXD6, which is an intermediate layer (gas barrier layer), and the PET layer, which is an inner layer and an outer layer, is increased, and the delamination resistance (peeling resistance) of the container itself is improved.

JP 2005-305676 A

  However, when the intermediate layer (gas barrier layer) is formed by mixing PET with nylon MXD6 as in the above method, the mixture of nylon MXD6 and PET becomes turbid due to the difference in refractive index between nylon MXD6 and PET during stretching ( Whitening) occurs, and the transparency of the container itself is impaired.

  This invention solves the said subject, and it aims at providing the multilayer container which keeps transparency of container itself, improving the peeling resistance between layers.

  In order to solve the above problems, a multilayer container according to the invention of claim 1 includes an inner layer and an outer layer made of a polyester resin, and at least one intermediate layer disposed between the inner layer and the outer layer. The intermediate layer is formed by mixing a heat-resistant amorphous polyester resin obtained by copolymerizing spiroglycol and a polyethylene terephthalate resin, and nylon MXD6.

  A multilayer container according to the invention of claim 2 is the multilayer container according to claim 1, wherein the intermediate layer is made of nylon MXD6 and the heat-resistant amorphous polyester resin in a weight ratio of 9: 1 to 1. It is formed by mixing at a ratio of 1: 9.

  Furthermore, the multilayer container according to the invention of claim 3 is the multilayer container according to claim 1 or 2, wherein the ratio of the thickness of the intermediate layer to the thickness of the inner layer and the outer layer is 5 to 50. %.

  As effects of the present invention, the following effects can be obtained. That is, according to the multilayer container, it is possible to maintain the transparency of the container itself while improving the peel resistance between the inner and outer layers and the intermediate layer.

It is the side view of the multilayer container which concerns on this invention, and the partial cross section schematic diagram of the side surface of the multilayer container.

  Below, the multilayer container 10 which concerns on this invention is demonstrated based on FIG.

  As shown in FIG. 1, the multi-layer container 10 includes a mouth portion 11, a shoulder portion 12 having a diameter increased from the mouth portion 11, a barrel portion 13 formed in a cylindrical shape, and a lower portion thereof having a diameter increased, and a barrel portion 13. The bottom part 14 which closes a lower end is comprised. In the multilayer container 10, a mouth part 11, a shoulder part 12, a body part 13, and a bottom part 14 are connected in order. The shape of the multilayer container 10 in FIG. 1 is merely an example of the multilayer container in the present invention, and the present invention is not limited to this shape.

  Further, each part of the multilayer container 10 (the mouth part 11, the shoulder part 12, the trunk part 13, and the bottom part 14) includes an inner layer 15, an outer layer 16, and intermediate layers 17 and 17a provided between the inner layer 15 and the outer layer 16. 17b and 5 layers (multilayer structure).

  The inner layer 15 and the outer layer 16 are layers that form the external shape of the container. The inner layer 15, the outer layer 16, and the intermediate layer 17 are formed of a polyester resin. As the polyester resin used for the inner and outer layers of the present invention, a conventionally known polyester resin comprising a dicarboxylic acid component and a diol component can be used, and preferably, polyethylene terephthalate is used.

  The polyester resin used for the inner and outer layers of the present invention contains known compounding agents for resins, such as colorants, antioxidants, stabilizers, various antistatic agents, mold release agents, lubricants, nucleating agents, and the like. can do.

  The intermediate layers 17, 17 a and 17 b are layers provided between the inner layer 15 and the outer layer 16. The intermediate layer 17 is a barrier layer formed by mixing polyester resin, and the intermediate layers 17a and 17b are formed by mixing nylon MXD6 and a heat-resistant amorphous polyester resin obtained by copolymerizing spiroglycol and polyethylene terephthalate resin.

  Nylon MXD6 is a crystalline polyamide formed by polycondensation of metaxylenediamine and adipic acid.

Examples of the heat-resistant amorphous polyester resin used for the intermediate layers 17a and 17b include a glycol component having a cyclic acetal skeleton of 5 to 60 mol% of ethylene glycol and 30 to 95 mol% of ethylene glycol, and terephthalic acid. And a polyester obtained by polycondensation of a dicarboxylic acid component containing at least one of esters in the range of 80 to 100 mol% (trade name “Artester” manufactured by Mitsubishi Gas Chemical Co., Ltd.).
The heat-resistant amorphous polyester resin used for the intermediate layers 17a and 17b preferably has a refractive index comparable to that of nylon MXD6 during stretching.

  Further, the intermediate layers 17a and 17b are formed by mixing nylon MXD6 and a heat-resistant amorphous polyester resin in a weight ratio of 9: 1 to 1: 9. Among these, the intermediate layers 17a and 17b are preferably formed by mixing nylon MXD6 and a heat-resistant amorphous polyester resin in a weight ratio of 8: 2.

  Furthermore, the intermediate layers 17a and 17b are formed at a ratio of 5 to 50% with respect to the thickness of the inner layer 15 and the outer layer 16. In particular, the intermediate layers 17 a and 17 b are preferably formed at a ratio of 5 to 20% with respect to the thickness of the inner layer 15 and the outer layer 16.

  The multilayer container 10 has a five-layer structure of PET / nylon MXD6 / PET / nylon MXD6 / PET, but is not limited to this. For example, the multilayer container 10 has a three-layer structure of PET / nylon MXD6 / PET. You may comprise.

The multilayer container 10 is formed by a conventionally known blow molding method such as direct blow molding or biaxial stretch blow molding. Among these, it is preferable to use a biaxial stretch blow molding method.
Below, the manufacturing method of the multilayer container 10 by the biaxial stretch blow molding method is demonstrated.

1. Production of Multilayer Preform Multilayer container 10 is produced by stretching a multilayer preform and biaxially orienting it.
In the production of a multilayer preform, a co-injection molding machine having a plurality of injection cylinders is used to co-inject the molten resin into the preform mold cavity by a sequential molding method or a simultaneous molding method. By this method, (1) the inner and outer layers are polyester resin layers, and (2) at least one intermediate layer is a mixture of heat resistant amorphous polyester resin copolymerized with spiroglycol and polyethylene terephthalate resin and nylon MXD6. (3) A bottomed multilayer preform having a multilayer configuration of three or more layers as a whole is produced.

2. Production of the multilayer container 10 The multilayer container 10 is produced by subjecting the above-mentioned multilayer preform to stretch blow molding. In the stretch blow molding process, the multilayer preform is adjusted to a temperature at which it can be stretched, and then inserted into a blow mold die cavity, and compressed blow is blown to perform stretch blow molding. Stretch blow molding can be performed by any of the conventionally known hot parison method or cold parison method.

  The barrel temperature at the time of molding the multilayer container 10 is 240 to 280 ° C., preferably the barrel temperature is 245 to 270 ° C., and more preferably the barrel temperature is 270 ° C.

  Examples of the present invention will be described below. The present invention is not limited to the following examples.

  Examples and Comparative Examples are evaluated by the following evaluation methods.

[Side impact test]
Side impact test device for the central portion (portion from the bottom portion 14 to 95 mm) of the body portion 13 of the multilayer container 10 that is filled with 300 ml of water at room temperature (23 ° C.) and then allowed to stand for 12 hours in a thermostat kept at 5 ° C. Was repeatedly hit and the number of hits until delamination occurred was measured. The presence or absence of delamination was determined visually. The multilayer container 10 was struck up to 100 times and struck until delamination occurred. In Examples 1 to 3 and Comparative Example 1, 12 (n = 12) samples of multilayer containers were tested, and in Comparative Example 2, 6 (n = 6) samples of multilayer containers were tested. .

(Example 1)
In Example 1, the structure of the multilayer container 10 was a two-kind five-layer structure of inner layer 15 / intermediate layer 17a / intermediate layer 17 / intermediate layer 17b / outer layer 16. In Example 1, the inner layer 15 and the outer layer 16 had a thickness of 0.3 mm, the intermediate layer 17 had a thickness of 0.04 mm, and the intermediate layers 17a and 17b had a thickness of 0.02 mm. Moreover, the barrel temperature at the time of shaping | molding of the multilayer container 10 was 245 degreeC. Furthermore, in Example 1, after the multilayer container 10 was molded, the test was performed after the multilayer container 10 was stored at a room temperature of 23 ° C.
The inner layer 15, the outer layer 16, and the intermediate layer 17 were formed of PET (“BK6180C” manufactured by Nippon Unipet Co., Ltd.).
The intermediate layers 17a and 17b are made of nylon MXD6 (“S6011” manufactured by Mitsubishi Gas Chemical Co., Ltd.) and heat-resistant amorphous polyester resin (“Altesta S1000” manufactured by Mitsubishi Gas Chemical Co., Ltd.) in a weight ratio of 8: 2. And mixed to form. The ratio of the intermediate layers 17a and 17b was 7 wt%.

(Example 2)
Example 2 was molded under the same requirements as Example 1 except that the barrel temperature at the time of molding the multilayer container 10 was set to 255 ° C.

(Example 3)
In Example 3, molding was performed under the same requirements as in Example 1 except that the barrel temperature at the time of molding the multilayer container 10 was 270 ° C.

(Comparative Example 1)
In Comparative Example 1, the shape of the container was the same as that of Example 1 (the shape of the multilayer container 10). In Comparative Example 1, the structure of the multilayer container was a two-kind five-layer structure as in Example 1. The thickness of the inner layer 15 and the outer layer 16 was 0.3 mm, the thickness of the intermediate layer 17 was 0.04 mm, and the thickness of the intermediate layers 17a and 17b was 0.02 mm. Moreover, the barrel temperature at the time of shaping | molding of the multilayer container 10 was 245 degreeC. Furthermore, in Comparative Example 1, after the multilayer container was molded, the test was performed after the multilayer container was stored at a room temperature of 23 ° C.
The inner layer 15, the outer layer 16, and the intermediate layer 17 were formed of PET (“BK6180C” manufactured by Nippon Unipet Co., Ltd.).
The intermediate layers 17a and 17b were made of nylon MXD6 (“S6011” manufactured by Mitsubishi Gas Chemical Co., Ltd.). Moreover, the ratio of the intermediate layer was 7 wt%.

(Comparative Example 2)
Comparative Example 2 was molded under the same requirements as Comparative Example 1 except that the test was performed after the multilayer container was stored at room temperature (23 ° C.) after the multilayer container was molded.

  As shown in Table 1, in each of Examples 1 to 3 according to the present invention, the average number of hits until delamination occurred was 60 times or more, and the average values of Comparative Examples 1 and 2 (14. 8 times and 25.5 times), and there were cases where delamination did not occur even when the maximum number of impacts (100 times) was reached. That is, by forming the intermediate layer as a layer in which nylon MXD6 and a heat-resistant amorphous polyester resin are mixed, the peel resistance between the inner layer, the outer layer, and the intermediate layer is improved.

  In addition, as shown in Examples 1 to 3, by raising the barrel temperature during the formation of the multilayer container 10 from 245 ° C. to 270 ° C., the average value of the number of impacts until delamination occurs is 63.5 times ( The number increased from Example 1) to 76.4 times (Example 3). That is, by increasing the barrel temperature at the time of forming the multilayer container, the peel resistance between the inner layer and the outer layer and the intermediate layer was improved.

[Bottle squeeze test]
The body 13 of the multi-layer container 10 (90 mm from the bottom 14) is pushed in by a compression jig (tip diameter 30 mm, made of nylon) attached to the crosshead of an autograph (AGS-5kNJ, manufactured by Shimadzu Corporation). The presence or absence of delamination due to indentation and the amount of indentation (mm) when delamination occurred were measured. The pushing amount of the multilayer container 10 into the body portion 13 was set to a maximum of 30 mm. For fixing the multilayer container 10, a positioning table (block) having a width that does not interfere with the ribs of the shoulder 12 of the multilayer container 10 was used. The trunk | drum 13 of the multilayer container 10 was fixed with the double-sided tape. In Example 8 and Comparative Example 6, the test was performed on samples of 6 (n = 6) multilayer containers.

(Example 4, Comparative Example 3)
Example 4 was molded under the same requirements as in Example 1 and Comparative Example 3 as in Comparative Example 1.

  As shown in Table 2, delamination occurred in all samples in Comparative Example 3, but delamination occurred in only one sample in Example 4 according to the present invention. That is, by forming the intermediate layer as a layer in which nylon MXD6 and a heat-resistant amorphous polyester resin are mixed, the peel resistance between the inner layer, the outer layer, and the intermediate layer is improved.

[Transparency test]
A sample (thickness 0.7 mm) was cut out from the body of the multilayer container, and the haze degree (haze value) of this sample was measured using a haze meter (NDH2000 model manufactured by Nippon Denshoku Industries Co., Ltd.) based on the test standard JIS K7136: 2000. ) Was measured.

(Example 5)
Example 5 was molded under the same requirements as in Example 1.

  As shown in Table 3, the haze degree (haze value) of Example 5 according to the present invention was satisfactory because it generally satisfied the value (haze value of 6% or less) required for highly transparent PET bottles. . That is, it can be said that the transparency can be maintained even when the intermediate layer is formed of a layer in which nylon MXD6 and a heat-resistant amorphous polyester resin are mixed.

10 Multilayer container 15 Inner layer 16 Outer layer 17, 17a, 17b Intermediate layer

Claims (3)

A multilayer container comprising an inner layer and an outer layer made of a polyester resin, and at least one intermediate layer disposed between the inner layer and the outer layer,
The intermediate layer is formed by mixing heat resistant amorphous polyester resin obtained by copolymerizing spiroglycol and polyethylene terephthalate resin, and nylon MXD6. The intermediate layer is
The multilayer container according to claim 1, wherein nylon MXD6 and the heat-resistant amorphous polyester resin are mixed at a weight ratio of 9: 1 to 1: 9. The ratio of the thickness of the said intermediate | middle layer with respect to the thickness of the said inner layer and an outer layer exists in the range of 5 to 50%. The multilayer container of Claim 1 or Claim 2 characterized by the above-mentioned.

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