JP5229602B2 - Masterbatches and plastic containers made using them - Google Patents

Description

  The present invention relates to a masterbatch and a plastic container manufactured using the masterbatch, and more particularly to a plastic container having an oxygen gas barrier property manufactured using a masterbatch that can be easily stored.

Of the master batches that are resin materials that are put into the molding machine, the master batch used to form a resin layer that blocks or absorbs specific substances is strictly stored and handled to avoid contact with the specific substances before molding. Need to be made. For example, in a kneaded product of polymetaxylylene adipamide resin (hereinafter also referred to as (polyamide) MXD6) and cobalt stearate, which is a resin having oxygen blocking / absorbing properties, oxygen absorption from the moment the polyamide and cobalt are mixed. Since the function is manifested, it is necessary to severely block oxygen and moisture after kneading, and handling of the masterbatch is extremely complicated. For example, in the drying process of the masterbatch, it is necessary not to absorb oxygen by dehumidification drying or vacuum drying with a low dew point, and the masterbatch after drying is also packed in a bag with high moisture and oxygen resistance, There is a need to pay attention to handling so that pinholes do not occur in the packaging bag.
JP 2005-8867 A JP 2004-182743 A

  An object of the present invention is to provide a master batch for use in forming a resin layer that blocks or absorbs a specific substance, which is easy to handle, and a plastic container manufactured using the master batch.

  The present inventors replaced the complex salt with a resin that does not react with the complex salt, instead of a method of obtaining a master batch by mixing a conventional complex salt with a resin that reacts with the complex salt to block a specific substance or exhibits an absorption function. It was found that the above-mentioned problems can be solved by mixing the master batch and the reactive resin in the molding stage.

  Accordingly, the masterbatch of the present invention is characterized by comprising a complex salt of an inorganic acid salt or an organic acid salt containing at least a transition metal catalyst and a thermoplastic resin that is substantially non-reactive with the complex salt. It is.

  According to the masterbatch of the present invention, there is no fear of deactivation due to absorption of a specific substance even if there is contact with a specific substance (oxygen or the like) to be blocked or absorbed at the stage of the masterbatch. Therefore, it is possible to dry the masterbatch even in a dryer that does not have a dehumidifying function, etc., and it is possible to use an inexpensive bag that does not block the specific substance for storage, and no special handling is required. In addition to improved performance, there is no reduction in the function of blocking / absorbing specific substances even when compared with conventional strict controls. In addition, the resin layer obtained by mixing the masterbatch and the reactive resin may sometimes have a secondary effect of an anti-peeling effect by increasing the interlayer adhesion strength when laminated with other resin layers. I understand.

  The effects will be specifically described below in accordance with an example of a specific process of the master batch for forming an oxygen barrier / absorbing layer which is a preferred embodiment of the present invention.

  Conventionally, (1) mixed extrusion of polyamide and cobalt stearate, (2) water cooling, (3) cutting, (4) drying, (5) obtaining a master batch, (6) gas barrier layer Co-injection molding was performed by mixing with PET during molding. In this process, (1) oxygen absorption function is developed at the stage of mixing extrusion, and oxygen absorption is increased at high temperature and high humidity. Therefore, (4) drying requires deoxygenation / dehumidification, (5) Storage of the masterbatch required moisture and oxygen prevention.

  On the other hand, in an example of a preferred embodiment of the present invention, (1) mixed extrusion of PET and cobalt stearate, (2) water cooling, (3) cutting, (4) drying, (5) master A batch is obtained, and (6) co-injection molding is performed by mixing with polyamide at the time of molding into a gas barrier layer. In this process, since (6) the oxygen absorption function is manifested for the first time in the molding stage, (4) drying and (5) storage of the masterbatch do not require special moisture and oxygen prevention, (6) It is also possible to dry with a normal dryer immediately before molding.

Master batch In the master batch of the present invention, a complex salt of an inorganic acid salt or an organic acid salt containing at least a transition metal catalyst and a thermoplastic resin that is substantially non-reactive with the complex salt are mixed.

  Since this masterbatch has not yet exhibited a function of blocking / absorbing specific substances such as oxygen, it is not particularly necessary to store the specific substances, and normal storage is possible. Further, even when the master batch absorbs moisture and needs to be dried, it is not necessary to consider deterioration of the specific substance absorption function in drying.

Complex salt The complex salt contained in the masterbatch of the present invention is a complex salt of an inorganic acid salt or an organic acid salt containing a transition metal catalyst. Preferred complex salts include cobalt compounds such as cobalt stearate and cobalt neodecanoate. By containing such a cobalt complex salt, a high oxygen blocking / absorbing effect can be obtained. More preferably, the cobalt concentration is 0.2 to 0.8% by weight of the master batch. If it is less than 0.2% by weight, the effect of improving the gas barrier property by cobalt is not sufficiently exhibited. On the other hand, if it is about 0.8% by weight, a gas barrier that is usually required even in consideration of the presence of a non-reactive resin. However, if the concentration is higher than this, stable production of the masterbatch becomes difficult, and mixed spots may occur during extrusion.

Non-reactive thermoplastic resin Non-reactive thermoplastic resin reacts with a complex salt of an inorganic acid salt or organic acid salt containing a transition metal catalyst contained in the masterbatch of the present invention to exhibit a blocking / absorbing function of a specific substance. It is a resin that is substantially free from the problem. Typically, such non-reactive thermoplastic resins include polyethylene terephthalate resin (PET resin), polyethylene resin (PE resin), and polypropylene resin (PP resin).

Reactive Thermoplastic Resin Reactive thermoplastic resin is a resin that exhibits a blocking / absorbing function for a specific substance by reacting with a complex salt of an inorganic acid salt or organic acid salt containing a transition metal catalyst contained in the masterbatch of the present invention. It is. Typically, such reactive thermoplastic resins include polymetaxylylene adipamide resin (polyamide, specifically MXD6), nylon 6 and nylon 6.6.

  This reactive thermoplastic resin is typically mixed with the masterbatch of the present invention just prior to molding. The mixing ratio is preferably 5 to 20% by weight with respect to 100 parts by weight of the reactive resin.

As a specific example, the complex salt concentration of the gas barrier resin obtained when the masterbatch and the reactive thermoplastic resin are mixed at various ratios is shown below. Here, as a suitable combination, PET resin was used as the non-reactive thermoplastic resin, cobalt stearate was used as the complex salt, and MXD6 was used as the reactive thermoplastic resin. MB1000 (1.1% by weight), which is a master batch (MB) with a cobalt concentration of 1000 ppm (1.1% by weight as cobalt stearate, and the amount of cobalt in cobalt stearate is 9.4%), MB2000 (2.1 wt%) with 2000 ppm, MB4400 (4.7 wt%) with 4400 ppm, MB8000 (8.5 wt%) with 8000 ppm, MB10000 (10.6 wt%) with 10,000 ppm were reacted. In the gas barrier resin when the gas barrier resin is obtained by mixing 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight and 20 parts by weight with respect to 100 parts by weight of MXD6 which is a heat-resistant thermoplastic resin. The concentration (ppm) is shown in the following table. The inside of the thick frame in the table is a relatively preferable range as the gas barrier resin. However, MB10000 has a problem that color kneading may occur due to incomplete mixing during pellet production.

Gas barrier layer The gas barrier layer that is suitably formed from the masterbatch of the present invention is a mixture and molding of the masterbatch of the present invention and a reactive thermoplastic resin, and the subsequent shape is layered. . When the molded product is a plastic container, a barrier layer is formed on the plastic container body. The gas barrier layer has a function of blocking / absorbing specific substances, but typically blocks or absorbs oxygen.

  The gas barrier layer is preferably formed by co-injection molding in a form sandwiched between other resin layers, and the weight of the gas barrier layer is 3 to 7% by weight with respect to the resin weight of the plastic container body. preferable. If it is less than 3% by weight, the gas barrier performance cannot be sufficiently exhibited, and if it exceeds 7% by weight, the recyclability of the plastic container is lowered.

  The gas barrier layer suitably formed from the masterbatch of the present invention comprises at least a polyethylene terephthalate resin, a complex salt of an inorganic acid salt or an organic acid salt containing a transition metal catalyst, and a polymetaxylylene adipamide resin. Preferably, it comprises 5 to 15 parts by weight of polyethylene terephthalate resin with respect to 100 parts by weight of polymetaxylylene adipamide resin. If it is smaller than the above parts by weight, the effect of improving the adhesion between the gas barrier layer and the resin layer is not sufficiently exhibited, and peeling or the like is likely to occur. If it is larger than the above-mentioned parts by weight, the gas barrier properties will not be sufficiently exhibited.

  In the plastic container obtained by using the masterbatch of the present invention, when placed in a high temperature environment such as a use application such as a hot warmer vendor, acetaldehyde and formaldehyde from the container are contained in the filling. May elute. Further, depending on the type of contents to be filled in the container, some may be altered by ultraviolet rays. In particular, when filling drugs, quasi-drugs, etc., the deterioration of the packing material due to ultraviolet rays becomes a problem.

  Then, the gas barrier layer which comprises the plastic container of the suitable aspect of this invention can also contain the compound which has an ultraviolet-ray shielding function or an acetaldehyde absorption function. These compounds can be added to the resin layer constituting the plastic container or provided in the resin as an ultraviolet shielding layer. However, in consideration of the recyclability and functionality of the container, they are added to the gas barrier layer. It is preferable to do.

  As the compound having an ultraviolet shielding function, a commercially available ultraviolet absorber (for example, tinuvin) is preferably used. These ultraviolet absorbers can be formed by adding them as a master batch or liquid injection to the molten polymer at the time of container molding. Further, a resin capable of shielding ultraviolet rays, for example, polyethylene naphthalate (shielding at 380 nm or less) may be formed in multiple layers as a gas barrier layer. Furthermore, various wavelengths can be shielded by adding not only ultraviolet rays but also black, red and sepia colorants.

  Moreover, as a compound which has an acetaldehyde absorption function, AA Scavengers (made by ColorMatrix) etc. can be used suitably, These can be added to a molten polymer at the time of container shaping | molding.

Plastic Container The plastic container of the present invention has at least one layer formed using the master batch of the present invention. This container is preferably formed by laminating a plurality of layers, and the outermost layer of this container is preferably made of the same type of resin as the non-reactive thermoplastic resin contained in the masterbatch.

  In manufacturing such a plastic container, a process for preparing a master batch for storage by mixing a polyethylene terephthalate resin and a complex salt of an inorganic acid salt or an organic acid salt containing a transition metal catalyst, and the storage master batch In addition, a step of preparing a gas barrier resin by mixing polymetaxylylene adipamide resin, and co-injection molding of the gas barrier resin and the polyethylene terephthalate resin to provide at least one gas barrier layer in the polyethylene terephthalate resin layer It can consist at least of the process of manufacturing the plastic container formed.

  Furthermore, in the method of the present invention, preferably, the plastic container obtained by the co-injection molding is subjected to biaxial stretch blow molding. By such biaxial stretch blow molding, a general PET bottle container filled with a beverage or the like can be obtained.

  When the plastic container according to the present invention is subjected to biaxial stretch blow molding, the minimum wall thickness is preferably 0.20 mm or more, more preferably 0.25 mm or more.

  The form of the plastic container obtained by the production method of the present invention is not particularly limited, and may be in the form of bottles, cups, bowls, etc.

  EXAMPLES Hereinafter, although the masterbatch of this invention and the plastic container manufactured using the same are demonstrated in detail by an Example, this invention is not limited to these Examples.

Proportion of master batch storage test PET (CB651G Totobo) and cobalt stearate (Wako Pure Chemical Industries) 95.3% and 4.7% by weight (the amount of cobalt in cobalt stearate is 9.4%) And MB4400 was produced by dry blending. Thereafter, the mixture is supplied to a co-rotating twin screw extruder having a screw diameter of 35 mm equipped with a strider die, melt kneaded at an extrusion temperature of 260 ° C., the strand is extruded from the strand die, cooled with water, and then pelletized by a pelletizer. The master batch of this invention was produced.

  On the other hand, MXD6 and cobalt stearate (Wako Pure Chemical Industries) were dry blended in a proportion of 95.3% by weight and 4.7% by weight, and then a conventional masterbatch was prepared in the same manner as in the preparation of the masterbatch of the present invention described above. MB4400 ′ was produced.

  For these master batches, the following four types of samples were prepared in order to grasp the oxygen absorption status by storage status.

  Sample 1: 100 g of a conventional masterbatch completely sealed with a 120 mm × 120 mm small aluminum pouch (capacity 50 cc).

  Sample 2: 100 g of a conventional master batch was completely sealed with a 120 mm × 120 mm small aluminum pouch (capacity 50 cc), and two 0.5 mm holes were formed.

  Sample 3: 100 g of a conventional master batch.

  Sample 4: 100 g of the master batch of the present invention as it is.

These samples 1 to 4 were sealed and stored in a large aluminum pouch of 200 mm × 200 mm (capacity 400 cc), and the change in oxygen concentration in the large aluminum pouch was measured. As the oxygen concentration meter, PAC CHECK 302 manufactured by MOCON was used. The results are shown in the following table.

  As is apparent from the above table, the masterbatch (sample 4) according to the present invention does not absorb oxygen, so even if the masterbatch is stored directly in a sealed large pouch, the oxygen concentration in the atmosphere in the large pouch Did not change. On the other hand, with regard to the conventional masterbatch, in the sample 3 in which the masterbatch is stored directly in the sealed large pouch, and in the sample 2 in which the masterbatch is stored in an incomplete packaging in the sealed large pouch, As can be seen from the decrease in the oxygen concentration in the inner atmosphere, it was revealed that oxygen in the atmosphere in the large pouch would be absorbed unless completely sealed as in Sample 1.

  From the above, it was confirmed that the master batch of the present invention does not need to block oxygen during storage.

Performance Evaluation of Gas Barrier Layer A multilayer laminated preform (23 g) in which a gas barrier resin obtained by mixing the master batch of the present invention and a reactive thermoplastic resin is sandwiched between PET layers is molded by co-injection molding. Use to make 280 ml PET bottles and evaluate the performance of the PET bottles to determine the suitable range of the mixing ratio of the masterbatch and the reactive thermoplastic resin and the amount of complex salt (cobalt) in the masterbatch. It was. The master batch is prepared by mixing PET (CB651G Far Tobo) and cobalt stearate (Wako Pure Chemical Industries) based on the amount obtained by reverse calculation so that the cobalt concentration in the gas barrier layer shown in the table is obtained, MXD6 was used as the reactive thermoplastic resin. The ratio of the gas barrier layer in the PET bottle was 5% by weight. The gas barrier layer was prepared by mixing the master batch (MB) at a ratio of 5 to 20 parts by weight described in the table with respect to 100 parts by weight of MXD6.

<Oxygen transmission test (gas phase)>
Under conditions of a temperature of 23 ° C. and a humidity of 40% RH, an oxygen permeation test was performed by a method known as the Mocon method using a 280 ml PET bottle using an oxygen permeation tester (OXTRAN, manufactured by MOCON). The results are shown below.

  From the above results, the barrier improvement factor (BIF) was calculated by dividing the numerical value before improvement (0.0300, which is the value without a gas barrier layer) by the numerical value after improvement. BIF of 10 or more (especially for all of those with a cobalt content of 300 ppm or more and an MB mixing amount of 20 parts by weight or less) (if it exceeds 10 times, the effect of preventing oxygen deterioration to some extent) Excellent barrier properties can be secured.

<Peel strength test (drop test)>
Master batch MB2000 was mixed with 100 parts by weight of MXD6 in the following parts by weight, preformed in the same manner as above to produce a 280 ml bottle, and a peel strength test (drop test) was performed as follows. It was. A 280 ml PET bottle was used and capped after 280 ml of water was filled. The bottle is stored in a thermostatic chamber (Espec: PL-2KP) with each temperature setting for one week, then dropped from the height of 50 cm or 100 cm once from the bottom and once from the side, and peeled off. Was confirmed. The test was performed with 10 pieces under each condition. In addition, heating cooling is a drop test after cooling to room temperature after storing at 60 ° C./1 week. The results are shown below.

  From the above results, it was confirmed that the peel strength was improved as the ratio of the master batch in the gas barrier layer (substantially the same as the ratio of PET in the gas barrier layer) was increased. Moreover, although the master batch amount (substantially equivalent to the PET amount) was slightly even at 5 parts by weight, it was confirmed that the peel strength was improved.

  When the final PET bottle is manufactured, if the cobalt content is 300 ppm or more with respect to MXD6 and the content of the gas barrier layer of the cobalt-containing PET is 5 to 20% by weight, both oxygen barrier properties and peel strength are good. became. From this result, the preferred range of the cobalt concentration in the master batch could be calculated backward. Specifically, if the cobalt concentration in the masterbatch is less than 0.2% by weight, even if mixed with MXD6, the amount of the masterbatch is required to be about 40% and the oxygen barrier property is lowered, which is not good. On the other hand, if the cobalt concentration in the masterbatch exceeds 0.8% by weight, it is not preferable because the color unevenness and strider dimensions become unstable and the production becomes difficult at the time of pellet production. Therefore, the cobalt concentration in the masterbatch is 0.2 to 0.8% by weight, and the mixing amount is 5 to 20 parts by weight with respect to 100 parts by weight of MXD6 (for example, 20 parts by weight of a masterbatch with a cobalt amount of 2000 ppm). It is confirmed that it is suitable to mix 100 parts by weight with MXD6).

Claims (9)

A plastic container having a layer structure in which at least one gas barrier layer is sandwiched between polyethylene terephthalate resin layers,
The gas barrier layer comprises:
A masterbatch comprising an inorganic acid salt or organic acid salt complex containing at least a transition metal and a polyethylene terephthalate resin, and a thermoplastic resin that acts with the complex salt in the masterbatch to express oxygen blocking or absorbing ability. And
The plastic container, wherein the content of the polyethylene terephthalate resin in the gas barrier layer is 5 to 20% by weight with respect to 100 parts by weight of the thermoplastic resin.   The plastic container according to claim 1, wherein the complex salt is a cobalt compound.   The plastic container according to claim 2, wherein a cobalt concentration is 0.2 to 0.8% by weight of the master batch. The plastic container according to any one of claims 1 to 3, wherein the thermoplastic resin is a polymetaxylylene adipamide resin. A method for producing a plastic container having a layer structure in which at least one gas barrier layer is sandwiched between polyethylene terephthalate resin layers,
Mixing a polyethylene terephthalate resin and a complex salt of an inorganic acid salt or an organic acid salt containing a transition metal , and preparing a masterbatch;
A ratio of 5 to 20% by weight of the polyethylene terephthalate resin in the masterbatch with respect to 100 parts by weight of the thermoplastic resin, with respect to 100 parts by weight of the thermoplastic resin that acts on the masterbatch to act as a complex salt to express oxygen blocking or absorption. Mixing to be included in the step of preparing a gas barrier resin;
Co-injecting the gas barrier resin and the polyethylene terephthalate resin to produce a plastic container having a layer structure in which the gas barrier layer is sandwiched between the polyethylene terephthalate resin layer;
A method for producing a plastic container, comprising:   A method for producing a plastic container, wherein the plastic container obtained by the method according to claim 5 is further biaxially stretch blow molded.   The method for producing a plastic container according to claim 5 or 6, wherein the complex salt is a cobalt compound.   The manufacturing method of the plastic container of Claim 7 whose cobalt concentration is 0.2 to 0.8 weight% of the said masterbatch. The method for producing a plastic container according to any one of claims 5 to 8, wherein the thermoplastic resin is a polymetaxylylene adipamide resin.