KR100896401B1 - Nanocomposite for multi layer container having excellent resistance against exfoliation - Google Patents

Abstract

The present invention relates to a nanocomposite composition for multilayer containers excellent in peel resistance, and more particularly, to a nanocomposite composition for producing a multilayer container excellent in durability, transparency, gas barrier properties, and peel resistance.

In order to achieve the above object, the nanocomposite composition according to the present invention is a resistance to peeling in a multi-layer container in MXD6, which is a polyamide resin containing a metha xylene group, or MXDI 60 to 99 wt% containing a methaxylene group and an isophthalic acid. Organic silicate layered silicate in a mixture of at least one selected from the group consisting of Nylon6, Nylon66, Nylon6 / 12, 6I / 6T, and copolymers thereof, for improving, from 40 to 1 wt%, from 0.5 to 100 parts by weight of the mixture. It is characterized by the addition of 10 parts by weight.

Nanocomposite, Multi-layer Container, Peeling, MXD6, MXDI

Description

Nanocomposite for multi layer container having excellent resistance against exfoliation

The present invention relates to a nanocomposite composition for multilayer containers excellent in peel resistance, and more particularly, to a nanocomposite composition for producing a multilayer container excellent in durability, transparency, gas barrier properties, and peel resistance.

Conventionally, PET-based resin containers are widely used in foodstuffs, beverages, medicines, etc. as packaging films, containers, etc. because of their excellent moldability, transparency, chemical resistance, heat resistance, mechanical strength, and the like. However, these PET-based resins have limited gas barrier properties, such as tomato-containing products (ketchup, tomato sauce), juices (fruit and vegetable juice), alcoholic carbonated drinks (beer, malt drink, champagne), and beverages for warming up (coffee, There is a problem that the use is limited in the field that requires high gas barrier properties such as car.

As one of the methods for solving this problem, a method of manufacturing a multilayer container has been proposed. In other words, to maximize the gas barrier properties of the container by producing a multilayer container having a structure consisting of an intermediate layer of one layer of barrier material in the thermoplastic polyester resin layer.

Japanese Laid-Open Patent Publication No. 56-64839 discloses a multi-layer container which forms a preform having a multi-layer structure consisting of a polyamide resin containing an outer layer and an inner layer with a PET layer, and an intermediate layer made of a methacrylic group-containing polyamide resin. A method is proposed. Since MXD6 nylon has a melting point close to that of PET, it shows very good moldability in combination with polyester. In addition, since the glass temperatures of the two resins are similar, it is easy to set an appropriate molding temperature at the time of blow blow molding.

However, when manufacturing multi-layer containers using gas barrier resins (MXD6, Aegis), which are generally used, it is possible to secure superior gas barrier properties than single-layer PET containers. When applied to beverages such as tea and other beverages, increasing the content of the gas barrier resin used to enhance the barrier properties of the multi-layer container may increase the cost and may cause recycling problems, and the barrier resin ( Peeling resistance of MDX6, Aegis) and PET layer becomes weak.

Therefore, when the preform is manufactured by the method described in the above publication, the adhesion between the polyester layer and the polyamide layer is poor, the preform configuration is poor, and the durability of the final molded multi-layer container is poor. Layer separation of the amide layer and multi-layer container formability may be poor. In addition, a high barrier cost is required to maintain the gas barrier properties of beverages that require high barrier properties due to their poor barrier properties.

The present invention has been invented to solve the above problems, the object of the present invention is to provide a nanocomposite composition for producing a barrier material that maintains excellent gas barrier properties and does not easily peel off from other layers while using a small amount in a multilayer container. have.

In order to achieve the above object, the nanocomposite composition according to the present invention is a resistance to peeling in a multi-layer container in MXD6, which is a polyamide resin containing a metha xylene group, or MXDI 60 to 99 wt% containing a methaxylene group and an isophthalic acid. For the improvement, 100% by weight of the organic layered silicate was added to a mixture of at least one selected from the group consisting of Nylon6, Nylon66, Nylon6 / 12, 6I / 6T, and copolymers thereof. 0.5 to 10 parts by weight is added.

Hereinafter, the present invention will be described in detail.

MXD6 is a polyamide resin containing a metha xylene group. It is made from m-xylenediamine and adipic acid, and has excellent barrier property against gases such as oxygen, carbon dioxide, and water vapor, and is widely used for packaging films and multilayer containers. . In addition, MXD-6 resin is suitable for use in combination with polyester resin because it has excellent usability with polyester resin and its glass transition temperature, melting point and crystallization rate are similar to polyester resin.

MXDI is a poly resin containing mechaxylene and isophthalic acid, and MXD6 is prepared from MXDI and adipic acid reacted with m-xylenedianim and isophthalic acid.

Such MXD6 or MXDI is a known resin which can be prepared by a known method or obtained from a commercial supplier, with a weight ratio of 60 to 99 wt%. When the content of MXD6 or MXDI in the nanocomposite composition exceeds 99wt%, it is not possible to control the increase of the crystallinity lowered by the organic layered silicate. The degradation is preceded. On the contrary, when the content of MXD6 or MXDI is less than 60wt%, a decrease in gas barrier property occurs due to a decrease in the ratio of aromatic nylon in the component.

The organically treated layered silicate is a nano-sized clay having a thickness of 1 nm and a length of 500 to 1000 nm. Since the layered silicate is difficult to peel and disperse in the polymer resin due to the strong attraction between the layers, in order to solve this problem, a low molecular weight organizing agent is intercalated between the silicate layered structures to give an organicized layered silicate. Layered silicates include montmorllonite, hectorite, beidelite, saponite, nontronite, mica and fluorinated mica. It is preferable to select one or more of them, and the organic material is quaternary ammonium, phosphonium, maleate, succinate, acrylate, acrylate, benzylic hydrogen ( It is preferable that the organic material including a functional group of the group consisting of benzyic hydrogens) and oxazoline.

Such organically treated layered silicates can be produced by known methods or obtained from commercial sources, the weight ratio being 0.5 to 10 parts by weight with respect to 100 parts by weight of the mixture. When the content of the organically treated layered silicate exceeds 10 parts by weight of the nanocomposite, the nano-sized layered silicate does not form exfoliated or intercalated forms of laminates in the polymer resin, thereby improving transparency due to improved crystallinity. Deterioration Rather, the desired level of gas barrier properties cannot be obtained. In addition, less than 1 part by weight, it is difficult to obtain the desired effect in the present invention.

Polyamide refers to synthetic polymers in which the structural units constituting the main chain are linked by amide groups, and polyamides in which the structural units linked by amide groups mainly consist of aliphatic monomers are called nylon.

Nylon is further subdivided into nylonmn and nylonm. In the former, dicarboxylic acid and diamine react to form an amide group. The number of carbons contained in diamine is represented by m and the number of carbons contained in dicarboxylic acid is represented by n. In addition, the amide group may be formed from a monomer having both an amine group and a carboxylic acid group, wherein the number of carbons contained in the monomer is called m, and such polyamide is called nylon m.

Nylon 6 is prepared by ring-opening polymerization of caprolactam. Nylon66 is prepared by the polycondensation reaction of hexamethylenediamine with adipic acid. Nylon 12 is prepared by ring-opening polymerization of Laurolactam. 6I / 6T is prepared by the polycondensation reaction of hexamethylenediamine with isophthalic acid and terephthalic acid. The copolymer is made of two or more kinds of homonylon raw materials, and has a feature of lowering melting point and improving transparency due to a decrease in crystallinity.

Method for producing a nanocomposite composition according to the present invention

Iii) selected from the group consisting of nylon 6, nylon 66, nylon 6/12, 6I / 6T and copolymers thereof in MXD6, a polyamide resin containing metha xylene, or MXDI 60-99 wt% containing methaxylene and isophthalic acid Drying at least one mixture of 40 to 1wt% of the mixture at a temperature of 80 to 90 ° C. for 4 to 5 hours, wherein the moisture content is dried to 50 to 400 ppm;

Ii) adding the organically treated layered silicate to the dried mixture at 0.5 to 10 parts by weight based on 100 parts by weight of the mixture to mix the mixture and the organically treated layered silicate; and

Iii) preparing a nanocomposite comprising the layered silicate using the mixture and the organically treated layered silicate using an extruder.

In the drying step, when the moisture content of the nylon composition is less than 50 ppm, pyrolysis occurs during the extrusion process of nylon, and when the moisture content exceeds 400 ppm, hydrolysis occurs during the extrusion process due to water, which is a problem in manufacturing the layered silicate nanocomposite. May cause.

When nylon resin is dried at 80 ~ 90 ℃ for less than 4 hours, the proper moisture content of 50ppm cannot be reached, and the layered silicate does not adequately peel and intercalate in the polymer resin during the extrusion process. Accelerate pyrolysis On the contrary, when drying for more than 5 hours at 80-90 ° C., yellowing of the nylon resin itself occurs, and the above drying conditions must be observed.

In the mixing step, when the content of the nanocomposite exceeds 10 parts by weight, the nano-sized layered silicate does not form exfoliated or intercalated forms of thin layers, thereby decreasing transparency due to improved crystallinity. It will not be possible to secure the level of gas barrier properties. In addition, less than 1 part by weight, it is difficult to obtain the desired effect in the present invention.

The extruder is a twin screw, with an L / D of 35 or more (L: screw length, D: screw diameter), and a kneading block to increase the degree of dispersion between the MXD6 or MXDI by peeling nano-sized layered silicates. It must contain at least 4 birds and at least 2 reverse blocks. In addition, the extrusion rate is set to 300RPM or more so that the exfoliated nano-layered silicate and MXD6 or MXDI are well mixed.

The temperature of the extruder is set as shown in Table 1, after mixing the MXD6 or MXDI and the nano-layered silicate in the extruder, the extrudate is passed through the die plate, cooled in a water bath and finally to produce a nanocomposite.

Table 1.

The method for manufacturing a multilayer container having a three-layer structure in which a barrier layer made of a nanocomposite composition according to the present invention and a polyester resin layer are bonded to both surfaces thereof includes a multi-layer container including melting, multi-layer preform injection, multi-layer preform reheating and blow molding. In manufacturing,

Iii) drying the nanocomposite in an 80-90 ° C. dryer for 4-5 hours before injection, wherein the moisture content is maintained at 50-400 ppm and more preferably 50-200 ppm, followed by drying and pretreating the nanocomposite; Wow

Ii) The injection temperature of polyester barrel is 290 ~ 295 ℃ and nanocomposite injection temperature is 270 ~ 285 ℃ in the multi-layer preform manufacturing process, and each resin is melted to inject polyester at 1300 ~ 1900psi and nanocomposite at 1000 ~ 1200psi. Co-injection with pressure to form a multilayer preform.

The nanocomposite and polyester resin from which moisture is removed are transferred from the dryer to the injection machine hopper, and are continuously supplied into the reciprocating screw injection molding machine by a predetermined amount and injected into the mold through melt plasticization fixing. Since a predetermined time is required until the injection process is completely completed, a considerable amount of resin remains in the injection machine hopper and is preferably maintained at 100 ° C. or higher, more preferably 160 ° C., to prevent moisture reabsorption. In addition, the temperature of the nanocomposite injector hopper is controlled at 70 ° C. or higher to remove the effect of improving the crystallinity by moisture.

If the moisture content of the nanocomposite is 50ppm or less, the crystallization degree of the injection molded preform is deteriorated by friction during the MXD6 melting process, which is the basic material of the nanocomposite, or when the water content increases more than 400ppm, the water in the nanocomposite acts as a crystal nucleating agent. Excessive causes peeling during blow molding.

If the barrel temperature is too high during injection molding, there is a high possibility that the preform is not cooled properly after injection.Therefore, there is a problem of exfoliation after blow molding by increasing the crystallinity of the preform.If the barrel temperature is too low, the polymer resin It does not melt properly, resulting in excessive shear viscosity, which prevents continuous injection molding.

In addition, if the injection pressure is less than 1300psi on the PET side, short shot occurs because it is not molded into the target weight and model. PET is injected, causing quality problems such as bars. The location and thickness of the barrier layer in the preform is determined by the speed of the barrier layer relative to the PET layer. For this reason, if the injection pressure on the barrier side is too large or too small, it is difficult to properly adjust the barrier speed, and thus it is difficult to adjust the position of the barrier layer below the support of the preform and below the bottom parting line.

In the present invention, a Kostec 48 cavity multi injection molding machine (FIG. 2) was used. Multi-injector is a molding system in which two kinds of polyester and barrier resin nanocomposite are injected into the cavity at the same time in the form of an open nozzle using two screws. Was prepared. In this case, as shown in FIG. 2, the preform has a structure including a nanocomposite as a barrier material between the polyester outer layers as an inner layer. The injection molding conditions of the multi-injection molding machine are summarized in Table 2.

Table 2.

The preform injection-molded under the above conditions is preheated by using a preform heating apparatus as shown in FIG. 3 using a heater such that the temperature is 104 ° C., and stretch blow molding is performed under conditions of a primary pressure of 9 bar and a secondary pressure of 40 bar. At this time, the stretching ratio of the abscissa is more than two times, and the stretching ratio of the ordinate is four times or more.

The multilayer container produced using the nanocomposite composition for multilayer container having excellent peeling resistance according to the present invention has improved gas barrier properties and peeling compared to the conventional multilayer container, and thus has excellent durability and excellent shape stability. In addition, the use of such a nanocomposite composition can reduce the amount of barrier resin used, does not pose a recycling problem, has a price competitiveness and has the advantage of using the current injection / blow processing equipment. Therefore, it can be usefully used as a container for carbonated beer containers or hot-filled coffee, tea storage, oxygen drinks, etc.

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention.

EXAMPLE

Nanocomposite prepared according to the present invention and the degree of separation, durability (improving peelability), gas barrier properties of the layered silicate of the multilayer container produced using the same were evaluated as follows.

1) Evaluation of Dispersibility of Nanomaterials in Nanocomposites

The extruded nanocomposite resin was prepared with a size of 30 μm using a microgenic ultramicrotome, and the degree of dispersion of the nanosilicate particles in the MXD6 resin matrix was measured using FE-TEM.

2) Crystallinity Evaluation of Preform Barrier Layer

After the injection molded preform body was cut, specimens of the barrier layer were taken and the crystallinity was evaluated as the size of the crystal and the distance between molecules using X-ray.

3) DSC measurement of preform barrier layer

Detecting during cooling at 10 ° C / min from melting state and melting point Tm defined as the end point of endothermic peak due to melting of crystals detected during heating at 20 heating rate using differential scanning calorimeter The crystallization is evaluated by the difference of the crystallization temperature Tc2 defined as the maximum point of the emission peak due to the crystallization.

4) Haze evaluation of preform barrier layer

The injection molded preform body was cut to take a specimen of the barrier layer, and the haze of the specimen was measured.

5) Drop test of bottle

After blow test of blow molded multi-layer container at 50Cm height, the multi-layer container is examined for peeling.

6) Oxygen Permeability Test

Oxygen permeability measuring device (Mocon, OX-TRAN 2/20) was placed in a blow moldable multi-layer container and stabilized with nitrogen for 24 hours at a temperature of 23 ° C and 50 RH%, and the oxygen permeability reached an equilibrium state. Measure the oxygen permeability until

7) Carbon Dioxide Permeability Test

After the blow moldable multi-layer container is mounted on the carbon dioxide permeability measuring device (Mocon, PermatranC 4/41), the 100% carbon dioxide atmosphere is made by using a vinyl cap on the outside of the multi-layer container. After stabilizing the inside with nitrogen, the carbon dioxide permeability is measured until the carbon dioxide outside the multi-layer container penetrates into the container and reaches an equilibrium state.

Examples and Comparative example

After drying the polyamide resin at 90 ° C. for 4 hours, the polyamide and the layered silicates were added and blended as shown in Table 3 at a speed of 50 rpm, followed by pretreatment to coat the nano-layered silicates on the polyamide surface. . The prepared resin was processed using a screw screw having a L / D of 35 at an extrusion rate as shown in Table 3 at 245 ° C. temperature to pass the extrudate through a die plate, cooled in a water bath, and finally to prepare a nanocomposite.

Polyethylene terephthalate having an intrinsic viscosity of 0.8 dl / g was selected and dried at 160 ° C. for 4 hours. , The nanocomposite resin of the composition ratio as shown in the following table is dried, and the multilayer preform is injection-molded so that the content of the nanocomposite is 7% using the dried resin.

At this time, the surface temperature of the multilayer preform is heated by a heater so as to be 104 ° C, and stretch blow molding is performed under conditions of a primary pressure of 9 bar and a secondary pressure of 40 bar.

Table 3.

Polyamide (wt%) Layered Silicate (wt%) MXD6 6I / 6T NY66 30B 93A 20A 15A Example 1 90 10 3 - - - Example 2 90 10 3 - - Example 3 90 10 - 3 - - Example 4 90 5 5 - - 3 - Example 5 90 10 - - - 3 Example 6 90 10 - - - 3 Comparative Example 1 50 50 3 - - - Comparative Example 2 90 10 15 - - - Comparative Example 3 100 3 - - - Comparative Example 4 100 - - - -

The layered silicate was separated on the nanocomposite to show a state dispersed in the MXD6 resin matrix (Example), and the comparative example 3 in which the layered silicate was not uniformly powdered in the polymer was compared with the gas barrier property when forming the multilayer bottle using the nanocomposite. Increasing effect is insignificant, and the layered silicate acts as a nucleating agent, causing the peeling of the multilayered disease.

Table 4. Crystal Analysis / DSC / Haze

Note> C.S (Å): The larger the crystallinity, the larger the crystallinity of the nanocomposite layer.

d002 (iii): The distance between the molecular chains of the nanocomposite layer, the higher the degree of orientation (crystallinity).

Tm-Tc2: The temperature difference is small. In general, in the case of injection molding, the crystallization rate is high because the crystallization rate is high, so the crystallinity is high.

As can be seen from the above table, the difference in Tm-Tc2 decreases, resulting in poor elongation during blow molding, and poor peelability of the container after blow molding.

In this development, it was confirmed that the durability of the container was improved by improving the peeling occurrence, which is a weak point of the multilayer container, by controlling the drying time, temperature condition, and injection condition of the barrier material in developing the nanocomposite.

Table 5. Gas Permeability / Releasing Resistance

Comparative Example 1 has excellent peeling resistance but is disadvantageous in terms of gas barrier properties. Through this development configuration, it is possible to manufacture a container excellent in peel resistance and gas barrier properties.

1 is a photograph using a microgenic ultramicrotomy to confirm the dispersibility of the nanosilicate of the molded specimen obtained through the Examples and Comparative Examples of the present invention,

2 is a schematic view of a Kortec 48 Cavity multi-layer injection machine,

3 is a schematic view of a preform heater.

Claims (3)

A polyamide resin containing methaxylene group MXD6 or MXDI containing methaxylene group and isophthalic acid 60 to 99wt% of nylon 6, nylon 66, nylon 6/12, 6I / Peeling resistance, characterized in that 0.5 to 10 parts by weight of an organically treated layered silicate is added to 100 parts by weight of the mixture to a mixture of at least one selected from the group consisting of 6T and copolymers thereof. This excellent nanocomposite composition for multilayer containers. The method of claim 1, wherein the organically treated layered silicate is to insert an organic material in the layered silicate structure, the organic material is quaternary ammonium (quaternary ammonium), phosphonium (Phosphonium), maleate, succinate (succinate) ), At least one member selected from the group consisting of organic substances including functional groups of the group consisting of acrylate, benzylic hydrogens, and oxazoline. Nanocomposite Compositions. The method of claim 2, wherein the layered silicate is montmorllonite, hectorite, beidelite, saponite, nontronite, mica, fluorinated mica The nanocomposite composition for multilayer containers having excellent peel resistance, characterized in that at least one selected from the group consisting of.

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