JP6415857B2 - Synthetic resin container and manufacturing method thereof - Google Patents

Description

  The present invention relates to a synthetic resin container such as a polyethylene terephthalate bottle (PET bottle) and a method for producing the same, and more particularly to a container having a barrier coating on the inner surface of the container body.

  As a container for storing soft drinks such as carbonated drinks, water, liquor, soy sauce, etc., since it is easy to handle in transportation, disposal, recycling, etc., synthetic resin containers such as polyethylene terephthalate bottles (PET bottles) are used. Many are used.

  Such a synthetic resin container has a defect that oxygen permeability is higher than that of a glass container, thereby shortening the quality maintenance period (shelf life) of the contents. For this reason, a barrier coating for reducing oxygen permeability is provided on the inner surface of the container main body, thereby extending the quality maintenance period of the contents.

  For example, Patent Document 1 discloses that a barrier coating made of a silicon oxide compound film such as a silica film is formed on the inner surface of a container body by chemical vapor deposition, and this barrier coating increases the barrier property against oxygen of the container body. A synthetic resin container is described. In this case, an organic silicon compound film is formed by chemical vapor deposition between the inner surface of the container body and the silicon oxide compound film, and this organic silicon compound film functions as an adhesive layer, so that oxidation by impact or the like is performed. In general, the silicon compound film is configured to suppress a decrease in barrier properties.

JP 2009-46162 A

  However, a barrier coating made of a silicon oxide compound film provided in a conventional synthetic resin container has a high barrier property against oxygen but a low barrier property against water vapor, and there is room for further improvement in this respect.

  The present invention was developed to solve such problems, and an object of the present invention is to provide a synthetic resin container having an improved barrier property against water vapor in addition to a barrier property against oxygen.

The synthetic resin container of the present invention is a synthetic resin container having a barrier coating on the inner surface of the container main body, wherein the barrier coating is formed on the inner surface of the container main body, and the organic silicon compound film a silica film formed on the inner surface of the silicon compound film, characterized by comprising the silicon oxynitride film formed on the inner surface of the silica film.

  In the synthetic resin container of the present invention, in the above configuration, the container body is preferably formed of a polyester-based synthetic resin material.

The method for producing a synthetic resin container according to the present invention is a method for producing a synthetic resin container having a barrier coating on the inner surface of a container body, wherein a first organic silicon compound film is formed on the inner surface of the container body. a film forming step, the inner surface of the organic silicon compound film, a second film forming step of forming a silica film, the inner surface of the silica film an inner surface of the silica film by the plasma containing nitrogen and nitrided And a third film forming step of forming a silicon oxynitride film.

  In the method for producing a synthetic resin container according to the present invention, in the above structure, the first film forming step is a chemical vapor phase in which a plasma treatment is performed by supplying a mixed gas containing hexamethyldisiloxane and oxygen into the container body. It is preferable that the second film formation step is performed by a chemical vapor deposition method in which a plasma treatment is performed by supplying a mixed gas containing hexamethyldisilazane and oxygen into the container body.

  In the method for producing a synthetic resin container according to the present invention, in the above configuration, the container body is preferably formed of a polyester-based synthetic resin material.

  According to the present invention, since the silicon oxynitride film having a high barrier property against water vapor is formed on the inner surface of the silicon oxide compound film having a high barrier property against oxygen, the barrier property against oxygen in the synthetic resin container is improved. In addition, the barrier property against water vapor can be enhanced.

  Further, according to the present invention, the silicon oxynitride film is formed on the inner surface of the silicon oxide compound film by nitriding the inner surface of the silicon oxide compound film with nitrogen-containing plasma. A silicon oxynitride film having a barrier property can be easily and reliably formed. As a result, a synthetic resin container having an improved barrier property against oxygen and an improved barrier property against water vapor can be easily produced.

It is the front view by which the synthetic resin container which concerns on one Embodiment of this invention was made into a part with a notch cross section. It is an expanded sectional view which expands and shows the principal part cross section of the synthetic resin containers shown in FIG. (A)-(d) is explanatory drawing which shows the procedure which forms an organosilicon compound film | membrane in the inner surface of a container main body, respectively. (A)-(c) is explanatory drawing which shows the procedure which forms a silicon oxide compound film | membrane on the inner surface of an organosilicon compound film | membrane, respectively. (A)-(c) is explanatory drawing which shows the procedure which forms a silicon oxynitride film | membrane on the inner surface of a silicon oxide compound film, respectively.

  Hereinafter, a synthetic resin container according to an embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, a synthetic resin container 1 according to an embodiment of the present invention has a container body 2. The container body 2 includes a mouth portion 2a formed in a cylindrical shape, a shoulder portion 2b continuous with the mouth portion 2a, a cylindrical body portion 2c continuous with the shoulder portion 2b, and a bottom portion 2d that closes the lower end of the body portion 2c. It is formed into a bottle shape.

  The container body 2 can be made of, for example, a polyester-based synthetic resin material. In the present embodiment, the container body 2 is a so-called PET bottle (PET bottle) formed of polyethylene terephthalate. In this case, the container body 2 can be formed by biaxial stretch blow molding.

  The container body 2 is not limited to one formed of polyethylene terephthalate, but may be formed of other synthetic resin materials such as polyethylene and polypropylene.

  A barrier coating 3 is provided on the inner surface of the container body 2 to prevent the oxygen and water vapor from passing through the container body 2. As shown in FIG. 2, the barrier coating 3 includes an organosilicon compound film 3a formed on the inner surface of the container body 2, a silicon oxide compound film 3b and a silicon oxide compound formed on the inner surface of the organosilicon compound film 3a. The three-layer film of the silicon oxynitride film 3c formed on the inner surface of the film 3b is stacked.

  The organosilicon compound film 3a is composed of an organosilicon compound containing at least silicon, carbon, and hydrogen. This organosilicon compound film 3a functions as an adhesive layer between the silicon oxide compound film 3b and the inner surface of the container body 2, and prevents the silicon oxide compound film 3b from being cracked by an impact or the like. Therefore, it is possible to suppress a decrease in the barrier property of the silicon oxide compound film 3b.

  The silicon oxide compound film 3b is composed of a silicon oxide compound. The silicon oxide compound film 3b can be a silica (SiOx) film, for example. The silicon oxide compound film 3b has a high barrier property against oxygen, and the barrier property against oxygen of the synthetic resin container 1 can be enhanced. The silicon oxide compound film 3b may be configured to contain a compound containing at least silicon, carbon, hydrogen, and oxygen in addition to the silicon oxide compound.

  The silicon oxynitride film 3c is also called silicon oxynitride (SiON), and is formed integrally with the inner surface of the silicon oxide compound film 3b by nitriding the inner surface of the silicon oxide compound film 3b. This silicon oxynitride film 3c has a high barrier property against water vapor. Therefore, the synthetic resin container 1 can exhibit a high barrier property against water vapor.

  Thus, in the synthetic resin container 1 of the present invention, the barrier coating 3 provided on the inner surface of the container body 2 includes the silicon oxide compound film 3b having a high barrier property against oxygen and the silicon acid having a high barrier property against water vapor. Since the nitride film 3c is included, high barrier properties can be exhibited against both oxygen and water vapor. Thereby, the quality maintenance period (shelf life) of the content when the content is stored in the synthetic resin container 1 can be extended.

  Further, in the synthetic resin container 1 of the present invention, the silicon oxynitride film 3c is provided on the inner surface of the silicon oxide compound film 3b, so that the silicon oxynitride film 3c is not provided. The oxygen barrier property of the container 1 can be further enhanced.

  Further, in the synthetic resin container 1 of the present invention, the silicon oxide compound film 3a is provided as an adhesive layer between the silicon oxide compound film 3b and the inner surface of the container body 2, so that the silicon oxide compound film is formed by impact or the like. It is possible to suppress the occurrence of cracks or the like in 3b, and to suppress the deterioration of the barrier property of the silicon oxide compound film 3b, that is, the deterioration of the barrier property of the synthetic resin container 1.

  Next, a procedure for manufacturing the synthetic resin container 1 having the above-described configuration by the method for manufacturing a synthetic resin container according to an embodiment of the present invention will be described.

  FIGS. 3A to 3D are explanatory views showing a procedure for forming an organosilicon compound film on the inner surface of the container body, and FIGS. 4A to 4C are each an organosilicon compound. FIGS. 5A to 5C are explanatory views showing a procedure for forming a silicon oxide compound film on the inner surface of the film, and FIGS. 5A to 5C each show a procedure for forming a silicon oxynitride film on the inner surface of the silicon oxide compound film. It is explanatory drawing shown.

  In the method for producing a synthetic resin container according to the present invention, a first film forming step for forming an organosilicon compound film 3a on the inner surface of the container body 2, and a silicon oxide compound film 3b on the inner surface of the organosilicon compound film 3a are formed. A second film forming step and a third film forming step of forming a silicon oxynitride film 3c on the inner surface of the silicon oxide compound film 3b are included.

  In the method for manufacturing a synthetic resin container according to an embodiment of the present invention, first, in the first film forming step, as shown in FIG. 3A, an accommodation space corresponding to the outer shape of the container body 2 is provided. The container body 2 is set inside the openable / closable external electrode 10, and the internal electrode 11 is inserted into the container body 2 from the mouth 2 a.

  In the present embodiment, the internal electrode 11 also has a function of a gas introduction pipe for introducing a gas, which will be described later, into the container body 2. However, the internal electrode 11 and the gas introduction pipe are connected to each other. It can also be set as the structure provided separately.

First, before introducing gas, the inside of the electrode is depressurized and maintained at a predetermined pressure. Next, as shown in FIG. 3B, hexamethyldisiloxane ( HMDSO: A mixed gas in which (CH ₃ ) ₃ Si—O—Si (CH ₃ ) ₃ ) and oxygen (O ₂ ) are mixed is supplied.

  Next, as shown in FIG. 3C, a microwave (for example, a high frequency of about 2.45 GHz) is applied between the external electrode 10 and the internal electrode 11, and the space between the external electrode 10 and the internal electrode 11 is applied. Plasma 12 is generated. When the plasma 12 is generated, the mixed gas introduced into the container body 2 is decomposed, and an organosilicon compound film 3a is formed on the inner surface of the container body 2 as shown in FIG.

  The application of microwaves between the external electrode 10 and the internal electrode 11 can be performed by pulse discharge that is turned on / off at a predetermined duty ratio. In this case, the duty ratio of the pulse discharge can be set to any value that does not cause the container body 2 to be overheated and contract.

  As described above, in the first film forming step, the mixed gas supplied to the inside of the container body 2 is subjected to plasma treatment, and the chemical vapor deposition method (CVD method), which is a kind of vapor deposition, is used to form the inside of the container body 2. An organosilicon compound film 3a that functions as an adhesive layer is formed on the surface.

Next, in the second film forming step, after the residual gas is exhausted from the inside of the container body 2 on which the organosilicon compound film 3a is formed, as shown in FIG. 2 is supplied with a mixed gas of hexamethyldisilazane (HMDSN: (CH ₃ ) ₃ —SiNH—Si (CH ₃ ) ₃ ) and oxygen (O ₂ ).

  Then, as shown in FIG. 4B, a microwave is applied between the external electrode 10 and the internal electrode 11 to generate plasma 12 between the external electrode 10 and the internal electrode 11. When the plasma 12 is generated, the mixed gas introduced into the container main body 2 is decomposed, and the inner surface of the organosilicon compound film 3a formed on the inner surface of the container main body 2 is decomposed as shown in FIG. The silicon oxide compound film 3b is formed to overlap.

  As described above, in the second film forming step, an organic silicon compound film formed on the inner surface of the container body 2 by the chemical vapor deposition method by plasma processing the mixed gas supplied into the container body 2. A silicon oxide compound film 3b is deposited on the inner surface of 3a.

Next, in the third film forming step, after the residual gas is exhausted from the inside of the container body 2 on which the silicon oxide compound film 3b is formed, as shown in FIG. 2 is supplied with nitrogen (N ₂ ) gas.

  Then, as shown in FIG. 5B, a microwave is applied between the external electrode 10 and the internal electrode 11. Thus, nitrogen plasma 13 is generated between the external electrode 10 and the internal electrode 11 inside the container body 2, and the inner surface of the silicon oxide compound film 3 b is treated with the nitrogen plasma 13. By such nitrogen plasma treatment, nitrogen enters the inner surface of the silicon oxide compound film 3b, that is, the inner surface of the silicon oxide compound film 3b is treated with nitrogen, and as shown in FIG. A silicon oxynitride film 3c is deposited on the inner surface of the film.

  In the first to third film forming steps, the pressure inside the container body 2, the flow rate of each gas supplied to the container body 2, and the output of the microwave applied between the external electrode 10 and the internal electrode 11 The film formation conditions such as the film formation time can be arbitrarily set so that the thicknesses of the respective films 3a to 3c have desired values.

  As described above, in the method for producing a synthetic resin container according to the present invention, the nitrogen oxide 13 is applied to the inner surface of the silicon oxide compound film 3b by performing nitrogen plasma treatment (nitriding treatment) on the inner surface of the silicon oxide compound film 3b with the nitrogen plasma 13. Since the film 3c is formed, the synthetic resin container 1 having the barrier coating 3 including the silicon oxide compound film 3b having a high barrier property against oxygen and the silicon oxynitride film 3c having a high barrier property against water vapor can be easily obtained. Can be manufactured.

  In addition, after the silicon oxide compound film 3b is formed on the inner surface of the container body 2, the silicon oxynitride film 3c is formed by performing nitrogen plasma treatment on the silicon oxide compound film 3b in a separate process. The film-forming property of the silicon oxynitride film 3c having the barrier property can be improved. Thereby, a silicon oxynitride film 3c having a desired thickness can be formed as a film covering the entire inner surface of the silicon oxide compound film 3b separately from the silicon oxide compound film 3b. Accordingly, oxygen generated by the silicon oxide compound film 3b can be formed. The barrier property against the water vapor of the synthetic resin container 1 can be further enhanced without impairing the barrier property.

  In order to confirm the effect of the present invention, a synthetic resin container of Examples of the present invention and a synthetic resin container of Comparative Examples 1 to 3 for comparison with the synthetic resin container of the present invention are prepared, These synthetic resin containers were subjected to a measurement test for barrier properties against water vapor, and the test results were compared. Moreover, about the Example and the comparative example 1, the measurement test of the barrier property with respect to oxygen was also performed, and the test result was compared.

  The synthetic resin container of the example was configured such that a 500 ml biaxially stretched blow bottle made of polyethylene terephthalate (PET) was used, and a barrier coating was formed on the first to third film forming steps. In all the steps from the first film forming process to the third film forming process, a microwave of 2.45 GHz was used. In the first film formation step, the pressure inside the bottle was maintained at about 35 Pa, a predetermined amount of HMDSO and oxygen gas was flowed, and 200 W of power was applied to form a film. In the second film forming step, the pressure in the bottle was kept at about 25 Pa, a predetermined amount of HMDSN and oxygen gas was flowed, and 1500 W of power was applied to form a film. In the third film forming step, the pressure in the bottle was kept at about 40 Pa, a predetermined amount of nitrogen gas was flowed, and power of 1500 W was applied to carry out the processing. At this time, the thickness of the entire film was 28 nm.

  The synthetic resin container of Comparative Example 1 has a configuration in which the processing of the third film forming step of the example is not performed, that is, the barrier film is formed of an organic silicon compound film and a silicon oxide compound film, and a silicon oxynitride film is provided. Not configured.

In the second film-forming step, the synthetic resin container of Comparative Example 2 contains hexamethyldisilazane (HMDSN: (CH ₃ ) ₃ —SiNH—Si (CH ₃ ) ₃ ) and oxygen (O ₂ ) inside the container body. ) And a mixed gas mixed with nitrogen (N ₂ ), and a synthetic resin container having a barrier coating formed by plasma treatment.

In the second film-forming step, the synthetic resin container of Comparative Example 3 contains hexamethyldisiloxane (HMDSO: (CH ₃ ) ₃ Si—O—Si (CH ₃ ) ₃ ) and oxygen (O _In addition to ₂ ), a mixed gas in which nitrogen (N ₂ ) was mixed was supplied, and this was made into a synthetic resin container having a barrier coating formed by plasma treatment.

  In the example and Comparative Examples 1 to 3, the film forming conditions in the first film forming step were all the same.

  The water vapor barrier is measured by filling 50 g of calcium chloride, sealing the opening with aluminum, storing it in an environment of 40 ° C.-90% RH, and increasing the amount of calcium chloride per day that permeates the container body. The amount (g) of water vapor was measured.

  For oxygen barrier properties, the OX-TRAN 2/20 measuring instrument manufactured by MOCON was used, the inside of the bottle was measured at 90% RH, the measurement environment 23 ° C.-55% RH, and atmospheric pressure, and the container The amount of oxygen per day (cc) permeating through the body was measured.

  As for the synthetic resin container in which the barrier coating is not formed on the inner surface of the container main body, the amount of water vapor and oxygen per day that permeate the container main body is measured in the same manner as described above. By dividing by the measurement results of Examples 1 to 3, the barrier improvement rate compared with the case where no barrier coating was formed on the inner surface of the container body, that is, the BIF (Barrier Improvement Factor) in Table 1 was calculated. The amount of water vapor per day that permeates the container body in a synthetic resin container in which no barrier coating is formed on the inner surface of the container body is 0.0834 g / day · Oxygen per day that permeates the container body. The amount was 0.030 cc / day · book.

  The results of the measurement test are shown in Table 1.

  From the measurement results shown in Table 1, the barrier coating provided on the inner surface of the container body includes a silicon oxide compound film having a high barrier property against oxygen and a silicon oxynitride film having a high barrier property to water vapor. It can be seen that the example synthetic resin container has a higher barrier property against water vapor than the synthetic resin container of Comparative Example 1 in which the silicon oxynitride film is not provided. It can also be seen that not only the barrier property of water vapor but also the barrier property against oxygen is enhanced.

Further, as in Comparative Examples 2 and 3, hexamethyldisilazane (HMDSN: (CH ₃ ) ₃ —SiNH—Si (CH ₃ ) ₃ ) or hexamethyldisiloxane (HMDSO: (CH ₃ ) ₃ Si—O— Unlike the example, the synthetic resin container having the plasma treatment of the mixed gas in which Si (CH ₃ ) ₃ ) and oxygen and nitrogen are all mixed may not have the effect of improving the barrier property against water vapor. I understand. That is, in the method for producing a synthetic resin container according to the present invention, a silicon oxide compound film having a desired thickness is formed on the inner surface of the silicon oxide compound film by forming a silicon oxide compound film and then performing a plasma treatment using nitrogen gas. Although a film can be reliably formed, as in Comparative Examples 2 and 3, hexamethyldisilazane (HMDSN: (CH ₃ ) ₃ —SiNH—Si (CH ₃ ) ₃ ) or hexamethyldisiloxane (HMDSO: When (CH ₃ ) ₃ Si—O—Si (CH ₃ ) ₃ ) is mixed with oxygen and nitrogen and plasma treatment is performed, the barrier coating does not have a silicon oxide compound film and a silicon oxynitride film. Therefore, it is considered that the effect of improving the barrier property against water vapor cannot be obtained.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Synthetic resin container 2 Container main body 2a Mouth part 2b Shoulder part 2c Body part 2d Bottom part 3 Barrier coating 3a Organosilicon compound film 3b Silicon oxide compound film 3c Silicon oxynitride film 10 External electrode 11 Internal electrode 12 Plasma 13 Nitrogen plasma

Claims (5)

A synthetic resin container having a barrier coating on the inner surface of the container body,
The barrier coating is
An organosilicon compound film formed on the inner surface of the container body;
A silica film formed on the inner surface of the organosilicon compound film;
A synthetic resin container comprising a silicon oxynitride film formed on the inner surface of the silica film.   The synthetic resin container according to claim 1, wherein the container body is made of a polyester-based synthetic resin material. A method for producing a synthetic resin container having a barrier coating on the inner surface of a container body,
A first film forming step of forming an organosilicon compound film on the inner surface of the container body;
A second film forming step of forming a silica film on the inner surface of the organosilicon compound film;
A third film forming step of nitriding the inner surface of the silica film with a plasma containing nitrogen to form a silicon oxynitride film on the inner surface of the silica film, Production method. The first film forming step is performed by a chemical vapor deposition method in which a plasma treatment is performed by supplying a mixed gas containing hexamethyldisiloxane and oxygen into the container body,
4. The synthetic resin container according to claim 3, wherein the second film-forming step is performed by a chemical vapor deposition method in which a mixed gas containing hexamethyldisilazane and oxygen is supplied into the container body to perform plasma processing. Manufacturing method.   The manufacturing method of the synthetic resin container of Claim 3 or 4 with which the said container main body is formed with the polyester-type synthetic resin material.

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