JP7383217B2 - Tube shoulder and its manufacturing method, and barrier tube - Google Patents

Description

The present invention relates to a tube shoulder, a method for manufacturing the same, and a barrier tube provided with the tube shoulder.

Oxygen barrier materials are sometimes used in laminated tubes to protect foods, medicines, etc. to prevent the contents from being oxidized and deteriorated by oxygen in the outside air. As a conventional oxygen barrier material, a common plastic film coated with a substance having oxygen barrier properties is known. Furthermore, oxygen barrier materials are also known in which aluminum, silica, alumina, or the like is deposited on a film in order to exhibit high oxygen barrier properties.

As a tube having barrier properties, the tube described in Patent Document 1 is known. This tube is formed by joining a shoulder part with insert molded aluminum foil as a barrier layer to a body part.
Since the tube described in Patent Document 1 uses metal, there is a problem in that it cannot be inspected for foreign substances using a metal detector or an X-ray inspection device.

Patent Document 2 describes that a shoulder part is formed by molding a resin composition obtained by melt-mixing a polyolefin, a metaxylylene group-containing polyamide, and a modified polyolefin. This shoulder part exhibits barrier properties, but since it does not use metal, it can also be used for the above-mentioned foreign object inspection.

Patent No. 2886966 Japanese Patent Application Publication No. 2017-159927

Patent Document 2 is by the inventor of the present application. The inventor conducted further studies and found a configuration and manufacturing process that more reliably exerts the barrier function, leading to the present invention.
An object of the present invention is to provide a tube shoulder that more reliably exhibits barrier properties and a method for manufacturing the same.
Another object of the present invention is to provide a barrier tube that exhibits barrier properties more reliably.

A first aspect of the present invention is a tube shoulder including a cylindrical mouth and a shoulder connected to one end of the mouth.
The mouth part and the shoulder part are made of a polyamide composed of a base polyolefin, polyamide A, which is a polyamide containing metaxylylene groups, and a linear aliphatic group, and a polyamide B prepared separately from the polyamide A, which has adhesive properties. The barrier layer is formed of a resin composition containing polyolefin, and a continuous layered barrier layer is formed of polyamide A and polyamide B over the entire circumference .

A second aspect of the present invention is a polyamide composed of a base polyolefin, a polyamide A which is a polyamide containing metaxylylene groups, and a linear aliphatic group , and a polyamide B prepared separately from the polyamide A ; Step A of preparing a mixture containing an adhesive polyolefin; Step B of heating and stirring the mixture to obtain a resin composition in which polyamide A and polyamide B are dispersed; and supplying the resin composition into a molding space. This method of manufacturing a tube shoulder comprises step C of compression molding the polyamide A and polyamide B to form a layered continuous barrier layer .

A third aspect of the present invention is a barrier tube comprising the tube shoulder of the present invention and a tube body having barrier properties and formed into a cylindrical shape, one end of which is joined to the outer edge of the shoulder. be.

According to the present invention, it is possible to provide a tube shoulder and a barrier tube that exhibit barrier properties more reliably.

It is a figure showing a tube shoulder concerning a first embodiment of the present invention. It is a figure which shows the kneading apparatus used for manufacturing the shoulder of the same tube. It is a figure which shows one process at the time of manufacturing the shoulder of the same tube. FIG. 1 is a diagram showing a barrier tube according to a first embodiment of the present invention. 2 is a microscopic image showing a cross section of the shoulder tube of Experimental Example 1. 3 is a microscopic image showing another cross section of the shoulder tube of Experimental Example 1.

One embodiment of the present invention will be described with reference to FIGS. 1 to 6.
FIG. 1 is a diagram showing a tube shoulder 1 according to the present embodiment, with the upper side being a side view and the lower side being a plan view. The tube shoulder opening 1 includes a mouth part 10 to which a lid is attached, and a shoulder part 20 connected to the mouth part 10.

The mouth portion 10 is formed into a cylindrical shape. The shape of the outer peripheral surface of the mouth part 10 can be determined as appropriate depending on the engagement structure with the lid attached to the mouth part 10 and the like. A structure may be adopted in which no lid is attached to the mouth portion 10, and in that case, the opening may be sealed with a thin body having barrier properties. Examples of the thin body include a sealing material having a structure in which biaxially stretched polyethylene terephthalate film, aluminum foil, and polypropylene resin are laminated in this order.
The shoulder portion 20 is formed into a substantially donut shape, and an inner edge 20a is connected to the lower end portion 10a of the mouth portion 10. Since the surface of the shoulder portion 20 is inclined, the outer edge 20b is located below the lower end portion 10a.

The mouth portion 10 and the shoulder portion 20 are integrally molded using a resin composition. By joining the outer edge 20b of the tube shoulder 1 to a separately manufactured tube body (described later), a tube capable of extrudably containing paste-like or gel-like contents is completed. When preparing a filled tube, the body of a cylindrical tube with both ends open and the shoulder of the tube are joined together, the contents are filled from the opening at the end of the body on the side without the shoulder, and then the body is sealed. do.

The resin composition constituting the tube shoulder 1 is composed of a base polyolefin, a metaxylylene group-containing polyamide (hereinafter referred to as "polyamide A"), and a polyamide composed of a linear aliphatic group (hereinafter referred to as "polyamide B"). ) and an adhesive polyolefin.

Polyamide A is also used in Patent Document 2 and has high barrier properties. However, in the course of the inventor's study, it was found that even if a resin composition containing polyamide A is formed into a layer, the barrier properties may not be improved in some cases. As a result of repeated studies by the inventor in order to exhibit stable barrier properties, a major factor was that polyamide A was distributed unevenly in the molded product, although it was layered, and there were areas where polyamide A was scarce or absent at all. It turned out to be one of the. Furthermore, it has been found that if polyamide A becomes fine particles in the process of making the distribution uniform, the barrier property itself is lost.

In other words, when forming a tube shoulder with barrier properties using polyamide A, it is necessary that the polyamide A is uniformly and continuously distributed in layers without becoming fine particles, but processing conditions It was extremely difficult to achieve this alone.

The inventors solved this problem by adding polyamide B in addition to polyamide A to the resin composition. Although polyamide B is inferior to polyamide A, it has a certain level of barrier properties. Furthermore, polyamide B has a similar melt viscosity to polyamide A and exhibits similar behavior during kneading.
Therefore, even if there are areas where the distribution of polyamide A is small, polyamide B follows and is distributed to cover the areas, so that a continuous barrier layer is maintained as a whole, and the molded product stably exhibits barrier properties. contribute to

The base polyolefin is not particularly limited, and materials having a wide range of melt viscosities can be used. Specifically, it is selected from, for example, linear low density polyethylene resin, low density polyethylene resin, medium density polyethylene resin, high density polyethylene resin, ultra-high molecular weight high density polyethylene resin, polypropylene resin, or ethylene, propylene, butene, etc. Resins made of copolymers of two or more types of olefins, and mixtures thereof can be used.

Polyamide A has diamine units and dicarboxylic acid units.
The diamine unit is not particularly limited, and specific examples include meta-xylylene diamine, para-xylylene diamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, and tetraxylylenediamine. Methylene diamine, hexamethylene diamine, nonane methylene diamine, 2-methyl-1,5-pentanediamine, etc. can be used.
The dicarboxylic acid unit is not particularly limited, and specifically includes, for example, α,ω-aliphatic dicarboxylic acid, alicyclic dicarboxylic acid such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, xylylene dicarboxylic acid, and naphthalene dicarboxylic acid can be used. Among these, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and the like are preferred because they do not inhibit the polycondensation reaction during the production of polyamide A and can easily yield a polyamide with excellent barrier properties.

Polyamide B is a resin obtained by ring-opening polymerization by supplying a raw material composition containing ε-caprolactam and water to a polymerization device equipped with a heating device.

As the adhesive polyolefin, a base polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride can be used.
Specific examples of unsaturated carboxylic acids or anhydrides thereof include acrylic acid, methacrylic acid, α-ethyl acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, and chloromaleic acid. , butenylsuccinic acid, and acid anhydrides thereof. Among these, it is preferable to use maleic acid, maleic anhydride, and the like.

The method of graft copolymerizing an unsaturated carboxylic acid or its anhydride to a polyolefin to obtain an adhesive polyolefin is not particularly limited, and various conventionally known methods can be used. Specifically, for example, a method of melting a polyolefin using an extruder or the like and adding a graft monomer to copolymerize it, a method of dissolving a polyolefin in a solvent and adding a graft monomer to copolymerize it, Examples include a method of making an aqueous suspension and then adding a graft monomer to copolymerize it.

A method for manufacturing the tube shoulder 1 according to the present embodiment and a method for manufacturing the barrier tube according to the present embodiment will be described.

First, a mixture of base polyolefin, polyamide A, polyamide B, and adhesive polyolefin is prepared (Step A). Next, the mixture is stirred while heating (Step B). When manufacturing the tube shoulder 1 by compression molding, step A is performed using a kneading device 100 equipped with a screw 110 as shown in FIG.

In order to more reliably obtain the above-mentioned distribution state of polyamide A, the heating temperature of the mixture in step A is important. Although the details will be described later, when the mixture is heated to a temperature exceeding the melting point of polyamide A, polyamide A is turned into fine particles by stirring by the screw 110. As a result, the tube shoulder manufactured from the resulting resin composition does not exhibit sufficient barrier properties. On the other hand, if the mixture is heated to a temperature below the melting start temperature of polyamide A, polyamide A will not become sufficiently flexible and cannot be uniformly dispersed within the mixture.
Therefore, in step A, the mixture is heated to a temperature above the melting start temperature of polyamide A and below the melting point. As a result, polyamide A can be uniformly dispersed in the mixture while suppressing the polyamide A from becoming fine particles, and the polyamide A can be uniformly and continuously distributed in the resulting resin composition. .
The heating temperature of the mixture in step A can be changed by adjusting the temperature of the screw 110. The heating temperature is preferably higher than the melting point of the base polyolefin, most preferably higher than the melting start temperature of polyamide B and lower than the melting point.

The mixture C kneaded by the screw 110 moves within the adapter 120 while maintaining a heated state. The mixture extruded from the adapter 120 into the molding space into a cylindrical shape is compressed into the shape of the tube shoulder 1 within the molding space (step C). At this time, as shown in FIG. 3, at the same time as the tube shoulder 1 is molded, the upper edge 60a of the tube body 60 that has entered the molding space 130 in advance and the outer edge 20b of the shoulder 20 are joined. Ru.

Through the above steps, as shown in FIG. 4, the barrier tube 51 of this embodiment, which includes the tube shoulder 1 and the tube body 60, is completed. Since the barrier tube 51 shown in FIG. 4 is before filling, the lower edge 60b of the tube body 60 is open. The barrier tube of this embodiment includes both an unfilled tube with an open lower edge 60b and a tube filled with contents and sealed with the lower edge 60b.

In the mixture C supplied into the molding space 130, polyamide A and polyamide B are uniformly dispersed without becoming too fine. By compressing this in the molding space 130, the polyamide A is stretched and arranged in a uniform layer in the mouth part 10 and the shoulder part 20. Furthermore, even if minute gaps occur in the stretched polyamide A, the gaps are covered with polyamide B with a high probability, and the manufactured tube shoulder 1 exhibits barrier properties with high reliability.
By joining the tube shoulder 1 that reliably exhibits barrier properties and the tube body 60 that has barrier properties, the barrier tube 51 also exhibits barrier properties with high reliability.

As explained above, in the tube shoulder 1 of this embodiment, polyamide A and polyamide B are uniformly dispersed and arranged in a layered manner. As a result, the reliability of exhibiting barrier properties increases. Therefore, the possibility of producing defective products with low barrier properties or no barrier properties is reduced, and the yield rate is also maintained high.
By combining the tube body 60 having barrier properties and the tube shoulder 1, the barrier tube 51 can be manufactured efficiently.

The tube shoulder of this embodiment will be further explained using an experimental example.
Polyethylene was used as the base polyolefin, and Admer (manufactured by Mitsui Chemicals, Inc.) was used as the adhesive polyolefin. The proportions of polyamide A and adhesive polyolefin in the mixture were fixed at 10%, and the proportions of base polyolefin and polyamide B were varied, and the experiments in Experimental Examples 1 to 5 were carried out using the kneading apparatus 100 described above. A tube shoulder opening was made. The temperature of the screw 110 was set at 215°C. This temperature is a temperature that satisfies the conditions of being higher than the melting start temperature and lower than the melting point for both polyamide A and polyamide B used, and is higher than the melting point of the base polyolefin.

The oxygen permeability of each tube shoulder was measured using the Mocon method. The results are shown in Table 1.

The oxygen permeability at the shoulder of a tube without barrier properties made only of polyolefin was approximately 0.014 cc/pkg·day. The average value of oxygen permeability in Experimental Examples 1 to 4 was about 1/2 to 1/3 of that of the tube shoulder made only of polyolefin, indicating that they exhibited barrier properties. The tube shoulder of Experimental Example 5 had low strength and easily cracked after manufacturing, so the oxygen permeability could not be measured.
From the above, it was considered that the content of polyamide B in the resin composition for forming the tube shoulder is preferably less than 40%.

Next, 20 barrier shoulders of Experimental Examples 1 and 4 were each produced, and variations in oxygen permeability were examined. The population standard deviation σ in the oxygen permeability of Experimental Example 4 was 0.0006, and the barrier properties were stable. On the other hand, although the average value of oxygen permeability of the barrier shoulder of Experimental Example 1 was lower than that of Experimental Example 4, the population standard deviation σ was 0.0029, which resulted in poor stability in terms of barrier performance.

For the shoulder of the tube that showed high oxygen permeability in Experimental Example 1, the shoulder 20, which is circular in plan view (see Figure 1), was cut at four locations at 90 degree intervals with the center angle, and each cut section was The cross section was observed under a microscope. Then, as shown in FIG. 5, there is a cross section Cs1 in which large lumps 25 mainly composed of polyamide A and polyamide B exist, while as shown in FIG. 6, there is a cross section Cs2 in which polyamide A and polyamide B are completely absent. It was done.
On the other hand, when the tube shoulder of Experimental Example 4 was similarly observed, a layered structure of polyamide A and polyamide B was observed in all cross sections.

From the above, it was shown that by adding polyamide B to polyamide A, a layered structure formed by polyamide A and polyamide B that exhibits barrier properties can be uniformly arranged over the entire circumference of the tube shoulder.

Although each embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and modifications and combinations of the configuration may be made without departing from the gist of the present invention. included.

1 Tube shoulder 10 Mouth 20 Shoulder 20b Outer edge 51 Barrier tube 60 Tube body

Claims (6)

a cylindrical mouth;
a shoulder connected to one end of the mouth;
Equipped with
The mouth portion and the shoulder portion are made of a base polyolefin, polyamide A which is a polyamide containing metaxylylene groups, and polyamide B which is prepared separately from the polyamide A, and is made of a polyamide composed of a linear aliphatic group. Formed from a resin composition containing adhesive polyolefin,
The polyamide A and the polyamide B form a barrier layer that is continuous in a layered manner over the entire circumference .
Tube shoulder. The content of the polyamide B in the resin composition is 10% or more and less than 40%,
The tube shoulder according to claim 1. The tube shoulder of claim 1, wherein the base polyolefin is polyethylene. Prepare a mixture containing a base polyolefin, polyamide A which is a polyamide containing metaxylylene groups, polyamide B which is a polyamide composed of a linear aliphatic group and is prepared separately from the polyamide A, and an adhesive polyolefin. Step A to
Step B of heating and stirring the mixture to obtain a resin composition in which the polyamide A and the polyamide B are dispersed;
Step C of supplying the resin composition into a molding space and compression molding it to form a continuous layered barrier layer of the polyamide A and the polyamide B ;
Equipped with
How to manufacture tube shoulders. In step B, the mixture is heated to a temperature lower than the melting point of either of the polyamide A and the polyamide B and higher than the melting start temperature of the polyamide A and the polyamide B.
The method for manufacturing a tube shoulder according to claim 4. The tube shoulder according to claim 1;
a tube body having barrier properties and formed into a cylindrical shape, one end of which is joined to the outer edge of the shoulder;
Equipped with
barrier tube.

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