JP2565508B2 - Laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention comprises an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) layer and a hydrophobic thermoplastic resin layer, particularly an ethylenically unsaturated carboxylic acid or A laminate obtained by laminating a thermoplastic resin modified with the carboxylic acid anhydride, in the relationship between the heating time and discharge rate in a Koka type flow tester, was obtained by using EVOH having unique flow characteristics, The present invention relates to a laminate having a very good appearance.

B. Conventional Technology EVOH is a useful polymer material that has gas barrier properties and high transparency, and is excellent in oil resistance and aroma retention, and is widely used in films, sheets, containers, and the like.

EVOH is usually obtained by adding a caustic alkali to an ethylene-vinyl acetate copolymer to saponify it, but when melt-molding the saponified product as it is, it is easily thermally decomposed, and the melt viscosity is significantly reduced, It cannot be used because it is strongly colored. Many measures have heretofore been taken for this improvement. For example, wash EVOH thoroughly with water,
It can be improved to some extent by adding an acid or immersing in an acid solution.
JP-A-48-25048, JP-A-51-88544, JP-A-51-88
No. 545 and JP-B-55-19242. Further, it is also possible to improve the melt moldability by adding a metal salt because the heat stabilizing effect of a certain metal salt is remarkable.
No. 954, JP-A-52-955, JP-A-56-41204 and the like.

These methods are mainly intended to reduce the change in viscosity with time during melting, and certainly a molded product having a good appearance can be obtained in melt molding for a short time. However, if the continuous melt molding is performed for a long time, for example, for 24 hours or more, a gel-like material or streaky unevenness is generated in the molded product, resulting in a poor appearance, and finally a molded product that can be used cannot be obtained.

This phenomenon also occurs when EVOH and a hydrophobic thermoplastic resin are coextruded or co-injection melt-molded. Ie EV
It is possible to obtain a multilayer laminate by coextrusion of OH and a hydrophobic thermoplastic resin through a thermoplastic resin modified with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride.
No. 2984, No. 58-35125 and No. 60-39548, this method has a drawback that the appearance of the obtained multilayer laminate gradually deteriorates when melt-molded for a long time.

C. PROBLEMS TO BE SOLVED BY THE INVENTION The present invention relates to the case where EVOH and a hydrophobic thermoplastic resin are laminated, especially through coextrusion or co-injection molding, through an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride. The purpose of the present invention is to obtain a laminate having a good appearance without deterioration over time for a long time.

D. Means for Solving the Problems The present invention relates to a laminate in which an EVOH layer and a hydrophobic thermoplastic resin layer are laminated via an ethylenically unsaturated carboxylic acid or a thermoplastic resin modified with the carboxylic acid anhydride. In the above, the change in viscosity of EVOH with time was measured by a Koka type flow tester, and the discharge speed was up to at least 15 minutes in the relationship between the heating time and the discharge speed at at least one point 10 to 80 ° C. higher than the melting point of the EVOH. Does not increase substantially, and the discharge rate for any heating time within 15 hours after 15 minutes is
It is in the range of 1/10 to 50 times the discharge speed after 15 minutes, and the discharge speed at any heating time within 2 hours to 10 hours is 2 to 50 times the discharge speed at least once after 15 minutes. It is a laminate characterized by using EVOH which exhibits the fluidity characteristics as in the inside.

E. More Detailed Description of the Invention EVOH suitable for obtaining a multilayer laminate of the present invention having a very good appearance means an ethylene-vinyl acetate copolymer saponified product or a third component, based on the vinyl acetate component. Mol%
After copolymerizing the following olefinic unsaturated monomers, saponified ethylene-vinyl acetate copolymer saponification product, ethylene content 20 ~ 60 mol%, preferably 20 ~ 55
Mol% and the saponification degree of the vinyl acetate component of the copolymer is
95% or more is preferable. If the ethylene content is less than 20 mol%, not only the water resistance and hot water resistance of the molded article will deteriorate, but also EVOH itself tends to gel,
The increase in the amount of fibers and the occurrence of streaks become remarkable, and the effect of the present invention becomes difficult to be exhibited. Also, the ethylene content
If it exceeds 60 mol% or if the degree of saponification is less than 95%, the gas barrier property deteriorates and the original characteristics of EVOH cannot be maintained.

EVOH is usually prepared by adding a caustic alkali or an alkali metal alcoholate to an alcohol solution of an ethylene-vinyl acetate copolymer for saponification, and then removing sodium acetate, which is a by-product of saponification, by washing with water. Can be obtained.
However, if it is melt-molded as it is, thermal decomposition is severe and the melt viscosity is remarkably reduced, and it is severely colored and cannot be used. Therefore, it is generally known that an operation such as addition of an acid, immersion in an acid solution, or addition of a combination of a certain kind of metal salt and an acid is carried out, and the moldability is improved by such a method. In particular, JP-B-55-19242 and JP-A-51
As disclosed in JP-A-91988, JP-A-52-954, JP-A-52-955, and JP-A-56-41204, the above-mentioned acid or a certain metal salt and an acid It has been conventionally said that those obtained by the treatment of adding a combination and having little change in melt viscosity with time during melt molding have good moldability. This is true in the case of melt molding for a short time, and a molded product having a good appearance and less coloring is obtained. However, when continuous melt molding is performed for a long time, for example, for 24 hours or longer, EVOH, a hydrophobic thermoplastic resin, and an ethylenically unsaturated carboxylic acid or a thermoplastic resin modified with the carboxylic acid anhydride becomes In the co-extrusion or co-injection multi-layer laminate of the system consisting of (1), a gel-like substance is generated, and at the same time, an interface instability phenomenon occurs during co-extrusion or co-injection, and a wavy appearance defect appears overall. In severe cases, the unevenness on the entire surface becomes severe, and the layers are bitten by each other, causing perforation and tearing. Even if the degree of poor appearance is small, a fine pattern that is satin-like may be formed on the entire surface, or a streak-like pattern may be formed. When such a coextruded product or a co-injected product having a poor appearance is post-processed, the poor appearance is further promoted and a net-like pattern is formed on the entire surface. Such wavy surface roughness and satin finish in coextrusion or coextrusion are related to the stability of the multilayer flow. If the flow is unstable, the surface becomes wavy when it is violent, and when it is low, satin,
It appears as a streak.

However, as described above, the present inventors prepared EVOH so as to show a special viscosity change with time, and subjected to melt molding at an appropriate temperature, surprisingly, in continuous melt molding for a long time. Have found the fact that the deterioration of the appearance of the multilayer laminate can be prevented remarkably.

That is, in the present invention, the change in viscosity of EVOH with time is measured by a Koka type flow tester, and the melting point of the EVOH {DSC
(Main endothermic peak temperature due to scanning speed 10 ° C / min)} In the relationship between the heating time and the discharging speed at at least one point 10 to 80 ° C higher than the discharging temperature, the discharging temperature does not substantially increase until at least 15 minutes. And, the discharge speed at any heating time within 15 hours after 2 minutes is in the range of 1/10 to 50 times the discharge speed after 15 minutes, and at any heating time after 2 hours and within 10 hours. Speed is at least once 15
The EVOH exhibiting flow characteristics within a range of 2 to 50 times the discharge speed after a minute is subjected to co-extrusion or co-injection melt molding. Here, the discharge rate by the Koka type flow tester means a value when a load of 10 kg / cm ² is applied using a nozzle of 1 mmφ × 10 mm ^L.

The discharge speed within 2 hours to 10 hours should be within the range of 2 to 50 times the discharge speed after 15 minutes at least once within this time, but within this time, the discharge speed increases as shown in FIG. preferable. Further, the discharge speed may be decreased up to 15 minutes, but the smaller the decrease rate is, the better. For example, the discharge speed after 15 minutes is the discharge speed after 0 minute.
It is 1/5 or more and 1 or less, preferably 3/5 or more and 1 or less.

Using EVOH with such specific flow properties,
By co-extrusion or co-injection melt molding of hydrophobic thermoplastic resin and thermoplastic resin modified with ethylenically unsaturated carboxylic acid or acid carboxylic acid anhydride, interfacial instability such as streaks and satin with gel-like material It is possible to obtain a multi-layered laminate having a good appearance, a good appearance, and an excellent interlayer adhesion without any phenomenon. The reason for this is not clear, but it is considered that this is probably due to the flow characteristics of EVOH, and further the interaction between the flow characteristics and the ethylenically unsaturated carboxylic acid or the modified thermoplastic resin by the carboxylic acid anhydride.

The EVOH composition of the present invention is obtained, for example, by the following method.

That is, EVOH contains (A) one or more metal salts of metals belonging to Group II of the Periodic Table, (B) pKa (acidity index at 25 ° C) of 3.5 or more, and an acid with a boiling point of 180 ° C or more under normal pressure. Substance and (C) pKa of 3.5 or more and an acidic substance having a boiling point of 120 ° C. or less under atmospheric pressure.

Examples of the metal belonging to Group II of the periodic table of the metal salt (A) include beryllium (Be), magnesium (Mg), calcium (Ca), zinc (Zn) and barium (Ba). Examples of the salt include carbonate, acetate, sulfate, phosphate, chloride and the like. Of these, calcium acetate and magnesium acetate are preferable from the viewpoint of controlling the viscosity change of EVOH with time and the hue of EVOH. When used, one or more of these metal salts can be used.

The acidic substance having a pKa (acidity index at 25 ° C) of 3.5 or more and a boiling point of 180 ° C or more under normal pressure of (B) is succinic acid,
Organic acids such as adipic acid, benzoic acid, capric acid, citric acid, lauric acid, inorganic acid substances such as boric acid, potassium dihydrogen phosphate and sodium dihydrogen phosphate, amino acids such as aspartic acid, aminobenzoic acid and glutamic acid However, the present invention is not limited to these. Of these, acidic substances having a boiling point of 250 ° C. or higher, particularly inorganic acidic substances are preferable. When used, one or more of these may be used. Also, (C) pK
Acetoacetic acid, formic acid, acetic acid and the like are mentioned as the acidic substance having a 3.5 or more and a boiling point of 120 ° C. or less under normal pressure, and acetic acid is more preferable.

As a method for adding these substances to EVOH, these substances may be directly added to EVOH and mixed, or an operation of immersing EVOH in an aqueous solution prepared by dissolving these substances in water may be used. May come.

The content of each substance in EVOH after adding these substances to EVOH is 0.0005 to 0.05% by weight, preferably 0.001 to 0.0% by weight in terms of the metal of (A) metal salt.
3% by weight, 0.002 to 0.2% by weight, preferably 0.002 to 0.2% by weight of (B) an acidic substance having a pKa of 3.5 or more and a boiling point of 180 ° C or more under normal pressure.
5 to 0.1% by weight, and (C) pKa of 3.5 or more, boiling point under normal pressure 12
It is 0.01 to 0.2% by weight, and preferably 0.02 to 0.1% by weight for acidic substances at 0 ° C or lower.

It is preferable that EVOH does not contain sodium acetate that is by-produced during saponification, but even if it is contained in an amount of about 0.05% by weight, the above characteristics are not impeded.

The content of each substance in EVOH is measured by the following method.

(1) 100 parts of EVOH metal salt belonging to Group II of the periodic table is put into a magnetic crucible and ashed in an electric furnace. Then, the ash is dissolved in 200 parts of an N / 100 nitric acid aqueous solution, and the metal of the metal salt is quantified by atomic absorption spectrometry.

(2) Extract the solute in the acidic substance EVOH having a pKa of 3.5 or more and a boiling point of 120 ° C or less under normal pressure with a solvent, and quantify the acidic substance in the extract by the neutralization titration method. Next, the quantitative method of a typical acidic substance is described.

Formic acid 100 parts of EVOH and 250 parts of water are placed in a closed container, and stirred at 95 ° C,
Heat for 3 hours to extract formic acid in EVOH. Then, using potassium permanganate solution as a titration method, formic acid in the extract is quantified by a redox titration method.

Acetic acid Acetic acid in EVOH is extracted with water in the same manner as formic acid. Then, an aqueous solution of sodium hydroxide is used as a titration method, and acetic acid in the extract is quantified by the neutralization titration method.

(3) Acidic substances with a pKa of 3.5 or higher and a boiling point of 180 ° C or higher under normal pressure The solute in EVOH is extracted with a solvent, and the acidic substances in the extract are quantified by the neutralization titration method. Next, the quantitative method of a typical acidic substance is described.

Succinic acid Succinic acid in EVOH is extracted with water as in the case of formic acid. Then, resorcin and concentrated sulfuric acid are added to the extract, heated to 126 to 130 ° C., cooled and quantified by a colorimetric method.

Adipic acid Extract adipic acid in EVOH with water as for formic acid. Then, the extract is dried to dryness, the precipitated adipic acid is dissolved in water, and adipic acid in the aqueous solution is quantified by the neutralization titration method using an aqueous sodium hydroxide solution as a titrant.

Benzoic acid Quantify in the same manner as adipic acid.

100 parts of capric acid EVOH and 250 parts of ethanol are put in a closed container and heated at 80 ° C. for 5 hours with stirring to extract capric acid in EVOH. Then, an aqueous solution of sodium hydroxide is used as a titrant, and capric acid in the extract is quantified by a neutralization titration method.

Lauric acid Quantify in the same manner as capric acid.

Citric acid Citric acid in EVOH is extracted with water as for formic acid. Then, acetic anhydride is added to the extract and heated, pyridine is further added to warm the extract, and the extract is cooled and quantified by a colorimetric method.

Boric Acid Boron is quantified in the same manner as the above-mentioned metal analysis method, that is, by atomic absorption spectrometry.

Sodium dihydrogen phosphate 100 parts of EVOH and 250 parts of an acetic acid aqueous solution of 1 g / concentration are put into a tightly closed container and heated at 95 ° C. for 3 hours under stirring to extract sodium dihydrogen phosphate in EVOH. Then, the phosphate ion in the extract is quantified by ion chromatography.

Potassium dihydrogen phosphate Quantify in the same manner as sodium dihydrogen phosphate.

Amino acids Extract the amino acids in EVOH with water as in the case of formic acid. Then, the amino acid in the extract is quantified by a known amino acid analysis method. For example, in the case of aspartic acid, fumaric acid is produced by dimethylsulfate treatment, and fumaric acid is quantified by polarography.

EVOH thus obtained at a temperature above the melting point,
EVOH and a hydrophobic thermoplastic resin are co-extruded or co-injection melt-molded through a thermoplastic resin modified with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride.
Since the melt viscosity of OH changes with temperature, and the effect of the substances contained in EVOH on the melt viscosity of EVOH also changes with temperature, the change in melt viscosity over time also changes intricately with that temperature. It is necessary to select an appropriate melt-molding temperature range in order to obtain the above-mentioned special change in melt viscosity over time.

The EVOH used in the present invention is a normal EVOH, for example, EVOH having a different ethylene content from the EVOH used in the present invention,
Further, other thermoplastic resins, plasticizers, other additives, etc. may be appropriately mixed within the range not impairing the object of the present invention and subjected to melt molding.

Next, EVOH and a hydrophobic thermoplastic resin are melt-coextruded or co-injection-molded through a thermoplastic resin modified with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride, which is used in the production of a multilayer thermoplastic resin. The modified thermoplastic resin with a plastic resin and an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride will be described.

First, as the hydrophobic thermoplastic resin, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, thermoplastic polyester such as polyethylene terephthalate, polyamide resin such as 6-nylon and 6,6-nylon, polystyrene A homopolymer, a copolymer or a mixture of polyvinyl chloride, a polycarbonate resin and the like is preferable. Of these, particularly preferred are polypropylene, polyethylene, ethylene-propylene copolymers, thermoplastic polyesters, polystyrene homo- or copolymers or mixtures.

Next, as the modified thermoplastic resin with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride, the olefin polymer is treated with an ethylenic unsaturated resin in consideration of the adhesiveness between the EVOH layer and the hydrophobic thermoplastic resin layer. A modified olefin polymer containing a carboxyl group obtained by chemically bonding a saturated carboxylic acid or an anhydride thereof (for example, by an addition reaction or a graft reaction) is suitable. Here, the olefin polymers are polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polypropylene, polybutene and other polyolefins, olefins and comonomers copolymerizable therewith (vinyl esters, unsaturated carboxylic acid esters). Etc.), for example, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ethyl ester copolymer and the like. Among these, ethylene-vinyl acetate copolymer (vinyl acetate content 5 to 55% by weight) and ethylene-acrylic acid ethyl ester copolymer (acrylic acid ethyl ester content 8 to 35% by weight) are preferable.

Ethylenically unsaturated carboxylic acid or its anhydride and ethylenically unsaturated monocarboxylic acid, its ester, ethylenically unsaturated dicarboxylic acid, its mono- or diester,
Examples thereof include anhydrides thereof, and of these, anhydrides of ethylenically unsaturated dicarboxylic acids are preferable. Specific examples thereof include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. Acids are preferred.

Addition amount or grafting amount (modification degree) of ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer
Is 0.01 to 15% by weight, preferably 0.02 to 10% by weight, based on the olefin polymer. Addition reaction of an ethylenically unsaturated carboxylic acid or an anhydride thereof to an olefin polymer,
The graft reaction can be obtained, for example, by a radical polymerization method in the presence of a solvent (such as xylene) and a catalyst (such as peroxide). The modified polyolefin polymer containing a carboxyl group thus obtained, ASTM-D-1238-
The MI measured at 65 ° C. at 190 ° C. is 0.2 to 30 g / 10 minutes, preferably 0.5 to 10 g / 10 minutes. These adhesive resins may be used alone or in combination of two or more.

The coextrusion method according to the present invention may be any of a multi-manifold merging system T-die method, a feedblock merging system T-die method, and an inflation method.

By subjecting the coextrusion molded product thus obtained to secondary processing, various molded products (film, sheet, tube, bottle, etc.) can be obtained. For example, (1) a multilayer co-stretched sheet or film obtained by uniaxially or biaxially stretching and heat-treating a multilayer molded product (sheet or film), (2) by rolling a multilayer molded product (sheet or film, etc.) (3) Multi-layer rolled sheet or film, (3) Multi-layer molded product (sheet or film, etc.) which is subjected to thermoforming such as vacuum forming, pressure forming, vacuum pressure forming and the like, (4) Multi-layer formed product (pipe) Etc.) to obtain bottles, cup-shaped containers and the like by stretch blow molding or the like. There is no particular limitation on such a secondary processing method, and known secondary processing methods (such as blow molding) other than the above can also be adopted.

As the layer structure of the coextrusion laminate of the present invention, when the modified thermoplastic resin with an ethylenically unsaturated carboxylic acid or its anhydride is represented by Ad and the hydrophobic thermoplastic resin is represented by P and P ′,
EVOH / Ad / P, P / Ad / EVOH / Ad / P, P / P ′ / Ad / EVOH / Ad / P, P / A
Examples thereof include d / EVOH / Ad / P ′ / P, and each layer may be a single layer or, in some cases, a multilayer. Further, a layer in which EVOH and Ad are blended with the hydrophobic resin layer P'may be used.

The coextruded laminate thus obtained has an excellent appearance and further has an excellent gas barrier property, and thus is suitably used as a material for food containers, for example, deep-drawing containers, cup-shaped containers and bottles. To be

As the co-injection method according to the present invention, various known co-injection methods can be used. Further, as in the method known in JP-A-61-152412, resin P, Ad and EVOH melted by a single clamping operation in a single preform mold using three injection cylinders are continuously and sequentially arranged in this order. The multi-layer preform can be molded by the injection method. The layer structure in this case is, for example, P / Ad / EVOH / Ad / P, P / Ad / EVOH / Ad / P / Ad / EVOH / Ad / P, or the like. Alternatively, a multi-layer preform or hollow container can be molded by co-injection molding using a co-injection nozzle or co-injection blow molding as disclosed in JP-A-60-34819.

Also in these co-injection moldings, as in the case of co-extrusion, when conventional EVOH is used, the EVOH layer and the ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride or the carboxylic acid anhydride are generated along with the generation of gel during long-term operation. Due to the instability phenomenon of the interface at the part where the interface of the adhesive resin layer made of modified thermoplastic resin merges (that is, inside the hot runner nozzle or preform mold), the wavy appearance defect, inter-layer digging, and satin finish , Appearance defects such as streaks occurred, and it was not possible to obtain products of commercial value, but EVOH was adjusted so as to show a special viscosity change of the present invention over time, and melt molding at an appropriate temperature. It was found that the deterioration of the appearance can be remarkably prevented by subjecting it to. This reason is considered to be the same as in the case of coextrusion.

The present invention will be further described with reference to examples. Parts or% in the examples are parts by weight, unless otherwise specified.
Alternatively, it indicates% by weight.

F. Examples Example 1 A solution consisting of 45 parts of an ethylene-vinyl acetate copolymer having an ethylene content of 38 mol%, 50 parts of methanol and 1 part of caustic soda was blown with methanol vapor at 110 ° C. under 3.5 Kg / cm ² G. Saponification reaction was carried out for 40 minutes while charging, and methyl acetate produced during the reaction was distilled out together with a part of methanol to remove it from the system. The resulting saponification reaction liquid (saponification degree of the copolymer 99.3
%) From a die with a hole with a diameter of 2 mm, methanol 10
%, The mixture was discharged into a water-methanol mixture at a temperature of 5 ° C. to solidify into strands and cut with a cutter to obtain pellets. After washing 3 times with 10 parts of ion-exchanged water for 1 part of this pellet, acetic acid 0.1% in 100 parts of ion-exchanged water,
It was dipped in an aqueous solution containing 0.01% benzoic acid, 0.03% calcium acetate and 0.01% magnesium acetate for 3 hours, drained and dried. Moisture contained in the pellet after drying is 0.1%, acetic acid is 0.06%, benzoic acid is 0.016%, calcium is 0.015%,
Magnesium was 0.0025%. The melt index of this pellet (190 ° C, load 2160g) is 2.5g.
The melting point was 176 ° C. for 10 minutes. The results of measuring the relationship between the heating time at 220 ° C. and the discharge rate of this pellet using a Koka type flow tester (Shimadzu 301 type, nozzle 1 mmφ × 10 mm ^L , load 10 Kg, all the following examples have the same conditions) A schematic diagram is as shown in FIG. 1, and the discharge speed at each point in FIG. 1 is as shown in Table 1.

Next, using this pellet, EVOH was used as the intermediate layer, and maleic anhydride-modified polyethylene (maleic anhydride content
A multilayer film having 0.5 wt%, vinyl acetate content of 20 wt%, MI 1.8 g / 10 min) as an adhesive layer and low density polyethylene as an inner layer and an outer layer was coextruded. The film was composed of low density polyethylene / adhesive resin / EVOH / adhesive resin / low density polyethylene {40μ / 5μ / 20μ / 5μ / 40μ (total thickness 110μ)}, and a film was formed under the following molding conditions.

The extruder used for EVOH is 60φ, the adhesive resin is 40φ, and the low density polyethylene is 65φ. The die confluence method is a feed block method (width 600mm), the die temperature is 220 ℃, and the cooling roll is 50. ℃, the take-up speed 10m / min EVOH resin temperature was 220 ℃. I ran for 150 hours continuously,
No generation of stripe-like material during film (refer to disadvantages of such small massive Fuitsushiyuai the stones) gel hard spots visible to the naked eye of the EVOH layer is 0.1 to 0.3 pieces / m ^2, the increase over time No trend was recognized. The appearance of the sheet was good, and no wavy pattern was generated.

Comparative Example 1 EVOH having an ethylene content of 38 mol% and a saponification degree of 99.3% was treated in the same manner as in Example 1 to obtain a pellet. 1 part of this pellet was washed 3 times with 10 parts of ion-exchanged water having a concentration of 0.05% acetic acid, and then 20 parts of ion-exchanged water was added with 0.02 adipic acid.
% And calcium acetate 0.01%, respectively, and immersed in an aqueous solution for 3 hours, and then dehydrated and dried. After drying, the water content of the pellets
0.1%, acetic acid 0.005%, adipic acid 0.03%, and calcium 0.005%.

The discharge rate measured with time using a Koka type flow tester at 200 ° C. is shown in Table 2, and the discharge rate was only decreasing with time. The schematic diagram is shown in FIG.

Next, using this EVOH pellet, a multilayer film having EVOH as an intermediate layer, maleic anhydride-modified polyethylene as an adhesive layer, and low-density polyethylene as an inner layer and an outer layer was prepared at the same die temperature and resin temperature of 200 ° C. as in Example 1. Was coextruded using the above equipment and conditions. As a result, after 20 hours, the generation of gel-like particles in the EVOH layer increased rapidly (Table 3), and the operation was stopped at 48 hours. Wavy appearance defects in the EVOH layer occurred from the start to the end of operation.

Control Example 2 As in Example 1, after ethylene-vinyl acetate copolymer was saponified, coagulated, cut and washed with water, 1 part of pellet was added.
3 parts in an aqueous solution containing 0.15% acetic acid in 100 parts of ion-exchanged water
It was immersed for a time, drained and dried. Moisture in the pellet after drying is 0.11%, acetic acid is 0.09%, calcium is 0.0005.
%, Magnesium was 0.0001% or less. The discharge rate was measured with time using a Koka type flow tester at 220 ° C. As shown in Table 4, the discharge rate was only decreasing with time.

Using the same apparatus as in Example 1 and using the same film structure, the coextrusion film formation was carried out at a die temperature and a resin temperature of 220 ° C. As a result, the occurrence of spots over time is shown in Table 5, and the operation was stopped after 20 hours. .

In addition, a wavy appearance defect in the EVOH layer occurred immediately after the start of operation and continued until it was stopped.

Example 2 Ethylene content 29 mol%, Propylene content 1 mol%
The ethylene-propylene-vinyl acetate copolymer of Example 1 was saponified, coagulated and cut in the same manner as in Example 1 to obtain a pellet. For 1 part of this pellet, 2 parts with 15 parts of ion-exchanged water
After washing twice, acetic acid 0.05%, sodium dihydrogen phosphate 0.02%, calcium acetate 0.02% in 100 parts of deionized water,
It was immersed in an aqueous solution containing 0.01% of magnesium acetate for 3 hours, drained, and dried. After drying, the pellets have a saponification degree of 99.4
%, Melt index 1.2 g / 10 min, melting point 177 ° C, water content in pellets 0.09%, acetic acid 0.03%, sodium dihydrogen phosphate 0.04%, calcium 0.01%, magnesium 0.0025%. It was As a result of measuring the relationship between the heating time and the discharge rate at 230 ° C. using a Koka type flow tester, it is as shown in FIG. 1 schematically, and the discharge rate at each point in FIG. 1 is as shown in Table 6.

This EVOH pellet and low density polyethylene (ASTM-D1
Melt index (MI) by 238 = 1.2g / 10min, below
LDPE), and maleic anhydride-modified polyethylene (MI 1.8 g / 10 min (maleic anhydride modification degree 0.5 wt%, vinyl acetate content 20 wt%)) as an adhesive resin. Membranes were made to make 110 μm thick films. The conditions were as follows.

1 film structure Outer layer LDPE (20μ) / Adhesive resin (10μ) / EVOH (20μ)
/ Adhesive resin (10μ) / Inner layer LDPE (50μ) (total 110
μ) 2 Equipment (1) LDPE 65φ extruder L / D = 22 (2) Adhesive resin 40φ 〃 〃 22 (3) EVOH 60φ 〃 〃 28 (4) Die (3 types, 5 layers annular die) 75φ 3 Molding Conditions (1) 65φ Extruder temperature 230 ℃ (2) 40φ 〃 220〃 (3) 60φ 〃 230〃 (4) Resin temperature 230〃 Operating for 120 hours continuously, while the film has streaks and wavy patterns The film surface was clean. Table 7 shows the occurrence of butterflies over time.
It is as follows.

Examples 3 to 9 EVOH pellets having the analysis values shown in Table 10, Column A were obtained by changing only the treatment conditions with the acid and the metal salt in Example 1. Each of them exhibited the viscosity change with time shown in Table 10, column B. The results of film formation of these pellets using the same coextrusion feedblock confluent five-layer film forming apparatus as in Example 1 are shown in Table 10, column C. The appearance was good without any streaks or wavy patterns.

Comparative Example 3 As in Example 2, after ethylene-propylene-vinyl acetate copolymer was saponified, coagulated, cut and washed with water, adipic acid 0.02% was added to 150 parts of ion-exchanged water per 1 part of pellets.
Immersed in an aqueous solution containing for 3 hours, and then drained and dried. Moisture contained in dried pellets is 0.09%, adipic acid is 0.03%
%, Calcium was 0.0007%, and magnesium was 0.0001% or less. The results of measuring the discharge rate with time using a Koka type flow tester at 230 ° C. are shown in Table 8, and the discharge rate was only decreasing with time.

As a result of performing co-extrusion inflation film formation in the same apparatus as in Example 2 with the same film structure and the same molding conditions (that is, resin temperature of 230 ° C.), the number of spots generated with time increased with time (Table 9). .

The appearance was poor due to the occurrence of a wavy pattern.

Control Examples 4 to 7 EVOH pellets with the analytical values shown in Table 11, column A were obtained by changing only the treatment conditions with the acid and the metal salt in Example 1. Each of them exhibited the viscosity change with time shown in column B of Table 11. Table 11 column C shows the results of film formation of these pellets using the same apparatus, conditions and film structure as in Example 1.

Example 10 The EVOH pellet obtained in Example 1 was used as an intermediate layer, polyethylene terephthalate (PET) was used as the inner and outer layers, and a maleic anhydride-modified ethylene-vinyl acetate copolymer was used as an adhesive resin. A multilayer sheet was coextruded using the same equipment as. The conditions were as follows.

1 sheet composition Outer layer PET / adhesive resin / EVOH / adhesive resin / inner layer PET = 40μ / 12μ / 80μ / 12μ / 40μ (total 184μ) 2 Resin used EVOH: obtained in Example 1 PET: 50% by weight of phenol And tetrachloroethane 50% by weight
Polyethylene terephthalate resin having an intrinsic viscosity [η] of 0.72 dl / g measured at a temperature of 30 ° C. dissolved in a mixed solvent of Adhesive resin: Maleic anhydride change Ethylene-vinyl acetate copolymer (vinyl acetate content 24 mol% , Maleic anhydride modification degree
1.8wt%) 3 Equipment used (1) PET 65φ extruder L / D = 22 (2) Adhesive resin 40φ 〃 〃 = 22 (3) EVOH 60φ 〃 〃 = 28 (4) Die: 3 types 5 layer feed Block Width 600mm 4 Molding condition (1) 65φ Extruder temperature 280 ℃ (2) 40φ 〃 220 ℃ (3) 60φ 〃 225 ℃ (4) Resin temperature 250 ℃ Continuously running for 120 hours, during which continuous lines There is no occurrence of gel, and gel-like particles in the EVOH layer (visible to the naked eye)
Was 0.1 to 0.3 pcs / m ² , and there was no tendency for increase over time, and the appearance was good.

Example 11 An ethylene-vinyl acetate copolymer having an ethylene content of 32 mol% was saponified, coagulated and cut in the same manner as in Example 1 to obtain a pellet (melting point 181 ° C). 1 part of this pellet was washed twice with 10 parts of ion-exchanged water, then in an aqueous solution containing 100 parts of ion-exchanged water containing 0.03% acetic acid, 0.02% benzoic acid, 0.015% calcium acetate and 0.01% zinc acetate, respectively. To 4
It was immersed for a time, drained and dried. After drying, the pellets have a saponification degree of 99.5%, melt index of 1.3 g / 10 minutes, water content of the pellets is 0.15%, acetic acid is 0.01%, benzoic acid is 0.03%.
%, Calcium 0.008% and zinc 0.004%.

As a result of measuring the relationship between the heating time and the discharge rate at 250 ° C. using a Koka type flow tester, the type is as shown in FIG. 1, and the discharge rate corresponding to each point in FIG. 1 is shown in Table 12. .

Polyethylene terephthalate resin (intrinsic viscosity [η] =
0.85 dl / g, melting point 265 ° C) and the EVOH resin and the adhesive resin obtained above, which had a vinyl acetate content of 24% and a maleic anhydride content of 1.1 wt% were modified with a maleic anhydride-modified ethylene-vinyl acetate copolymer resin. It is fed to three separate extruders, and the extrusion temperature is 250 ℃ for EVOH resin, 278 ℃ for polyethylene terephthalate resin (PET), and 250 ℃ for adhesive resin.
Extruded under the conditions of, the resin temperature in the die is PET280 ℃, EV
OH resin and adhesive resin are combined into a multi-layer tubular die at 250 ° C and outer layer PET / adhesive resin / EVOH / adhesive resin / inner layer PET =
Tube outer diameter of 25.0 mm consisting of 1.0 mm / 0.1 mm / 0.3 mm / 0.1 mm / 2.0 mm
A three-kind five-layer pipe (total layer thickness: 3.5 mm) was extruded. Consecutive 1
After running for 20 hours, there was no generation of streaks and lumps, and a multilayer pipe with a good appearance could be obtained. The obtained multi-layer pipe was cut into a length of 13.0 cm, one end was sealed, and a cap-capable neck portion was formed on the other end to obtain a multi-layer preform. This multi-layer preform was heated to 105 ° C., biaxially stretch-blowed by stretching a stretching rod and blowing air in a mold to form a multi-layer bottle having a capacity of 1. The obtained multi-layer bottle had excellent carbon dioxide gas barrier properties and was suitable as a carbonated beverage container.

Comparative Example 8 An ethylene-vinyl acetate copolymer having an ethylene content of 32 mol% was saponified, coagulated and cut in the same manner as in Example 1 to obtain a pellet. 1 part of this pellet was washed twice with 10 parts of deionized water, and then 100 parts of deionized water was added to acetic acid.
It was immersed in an aqueous solution containing 0.03% for 4 hours, drained and then dried. After drying, the pellets have a saponification degree of 99.5%, a melt index of 1.3 g / 10 minutes, and a moisture content of 0.15%.
Acetic acid was 0.01%.

Table 13 shows the results of measuring the relationship between the heating time and the discharge rate at 250 ° C using a Koka type flow tester.

Polyethylene terephthalate resin (intrinsic viscosity [η] =
0.85, melting point 265 ° C) and above EVOH resin, and vinyl acetate content 24% as adhesive resin, maleic anhydride content 1.
1 wt% maleic anhydride modified ethylene-vinyl acetate copolymer resin was used in the same conditions as in Example 11 under the same conditions as in outer layer PET / adhesive resin / EVOH / adhesive resin / inner layer PET = 1.0 mm.
3 types with a pipe outer diameter of 25mm consisting of /0.1mm/0.3mm/0.1mm/2.0mm
A layer pipe (total layer thickness 3.5 mm) was extruded. 3 hours after the start of the operation, streaks started to appear and the appearance of the streaks became more severe with time, and the operation was stopped at 6 hours. A multi-layer preform was made from the obtained pipe and blow-molded to make the multi-layer bottle 1. However, due to the streaks, a bottle having a good appearance could not be obtained.

Example 12 An ethylene-vinyl acetate copolymer having an ethylene content of 32 mol% was obtained in the same manner as in Example 1 to obtain the following dried pellet (melting point 181 ° C).

Degree of saponification 99.3% Melt index 4.8g / 10min Content of acetic acid 0.02% Content of benzoic acid 0.02% Calcium 〃 0.006% Magnesium 〃 0.002% Relationship between heating time and discharge rate at 260 ℃ using Koka type flow tester The result of measurement is of the type as schematically shown in FIG. 1, and the discharge speed corresponding to each point in FIG. 1 is as shown in Table 14.

Intrinsic viscosity [η] = 0.73dl / g, melting point 258 ° C PET and above
EVOH and adhesive resin (Ad) as maleic anhydride modified ethylene-vinyl acetate resin (melt index 4.0g / 10g
Min, vinyl acetate content 24wt%, maleic anhydride modification degree 1.
PET / Ad / EVO using a co-injection machine with three injection cylinders and a single preform mold.
H / Ad / PET = 1.0mm / 0.1mm / 0.3mm / 0.1mm / 2.0mm (center average thickness of the body) 3 types 5 layers preform (outer diameter 25mm length
130mm) was made by co-injection molding.

Although the product was operated for 120 hours continuously, no preforms or spots were found and a preform with good appearance was obtained.

This preform was heated to 105 ° C., and biaxially stretch-blown by stretching with a stretching rod and blowing air in a mold to form a multilayer bottle having a capacity of 1. The obtained multi-layer bottle was excellent in carbon dioxide gas barrier property and oxygen barrier property and was suitable as various beverage containers.

Control Example 9 EVOH as shown below was obtained.

Ethylene content 32 mol% Saponification degree 99.3% Melt index 4.8g / 10min Acetic acid content 0.01% The relationship between heating time and discharge rate was measured at 260 ℃ using a Koka type flow tester. It was on the street.

Multi-layer preform was co-injection molded under the same equipment and conditions as in Example 12 except that the above resin was used as EVOH.
The streaky substance was more than 4 hours after the molding, and this was biaxially stretch blow-molded to mold a bottle having a capacity of 1, but only a poor appearance was obtained due to the streaks.

Control Example 10 100 parts of a 40% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 30 mol% was added with 10 parts of sodium hydroxide.
% Methanol solution was added, and the mixture was kneaded at a temperature of 40 ° C. for 3 hours. After the completion of this primary saponification reaction, acetic acid was added to neutralize the mixture, and 60 parts of methyl acetate was added to complete the precipitation, which was then filtered and dried to obtain particles larger than 10 mesh (6% of all particles).
%) Was removed by sieving.

100 parts of the partially saponified product thus obtained was put into 500 parts of a 1% aqueous solution of sodium hydroxide, and the mixture was stirred for 3 hours in a slurry at a temperature of 65 ° C. for secondary saponification, and then neutralized with acetic acid. The particles are filtered off and 1,000 parts of water are added to add 30 parts.
The operation of stirring at 1 ° C. for 1 hour and filtering off was repeated 3 times.
The content of sodium acetate in the particles was 0.22%.

Next, 100 parts of the dried particles are mixed with 500 parts of water to form a slurry again, 10 parts of a 5% aqueous solution of acetic acid and 18 parts of a 1% aqueous solution of primary calcium phosphate are added, and the mixture is stirred at 30 ° C. for 4 hours and then filtered. Dried.

The EVOH having a saponification degree of 99.0 mol% thus obtained was measured for the relationship between the heating time and the discharge rate when heated to 230 ° C. using a Koka type flow tester, and the curve of Comparative Example 1 in FIG. The curve was similar to the above, and the discharge rate was only decreasing, and the discharge rate did not increase even if the heating time exceeded 10 hours.

Using this EVOH, except that the resin temperature of EVOH was 230 ° C., co-extrusion film formation was carried out in the same manner as in Example 1, and after 18 hours, many gel-like particles were generated in the EVOH layer, and in 20 hours I stopped driving. The wavy appearance defect in the EVOH layer occurred from the start of operation and deteriorated over time.

Control Example 11 100 parts of dry particles of EVOH obtained in the same manner as in Control Example 10 was mixed with 500 parts of water to form a slurry again, and acetic acid 0.26
Parts, 0.08 parts of lactic acid and 0.12 parts of primary calcium phosphate were added, and the mixture was stirred at 30 ° C. for 4 hours, filtered, and dried.

The ethylene content thus obtained was 30 mol% and the degree of saponification was 9
When the relationship between the heating time and the discharge speed when heated to 230 ° C was measured for 9.0 mol% EVOH using a Koka type flow tester, the discharge speed was only decreasing and the heating time was 10 hours. The discharge speed did not increase even when the value exceeded.

Using such EVOH, co-extrusion film formation was performed in the same manner as in Example 1 except that the resin temperature of EVOH was 230 ° C., and after 10 hours, many gelled spots were observed in the EVOH layer, and in 15 hours I stopped driving. Vertical streaks in the EVOH layer occurred around 5 hours after the start of operation and gradually increased until the time of operation stop.

Control Example 12 Ethylene content 31 mol%, Saponification degree 99.1 mol%, 210 ° C
Melt index (MI) 4.0 in 100 parts EVOH, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O 0.05 wt% and (C ₁₇ H
For a resin composition containing 0.03 wt% of ₃₅ COO) ₂ Ca, the relationship between heating time and discharge speed when heated to 230 ° C was measured using a Koka type flow tester. The speed gradually increased.

Using such EVOH, except that the resin temperature of EVOH was 230 ° C., co-extrusion film formation was carried out in the same manner as in Example 1, and no abnormal molding occurred from the start of operation to 8 hours later. After that, a poor grain-like appearance was generated and gel frequently occurred.

Control Example 13 Ethylene content 30 mol%, Saponification degree of vinyl acetate part 9
100 parts of powder of 9.0 mol% saponified ethylene-vinyl acetate copolymer (weight part, the same applies below) was put into 1000 parts of water to form a slurry, and 2 parts of orthophosphoric acid of 85% concentration was added thereto. It was thoroughly stirred, then filtered, washed with warm water and finally dried. Next, 0.5% by weight of the saponified ethylene-vinyl acetate copolymer containing orthophosphoric acid was added.
After mixing magnesium stearate of 1), it was once fed to the extruder to form pellets.

For such pellets, using a Koka type flow tester, when the relationship between the heating time and the discharge rate when heated to 210 ° C. was measured, the discharge measurement was only decreasing, and the heating time exceeded 10 hours. However, the discharge speed did not increase.

Using such pellets, except that the resin temperature of EVOH was 210 ° C., coextrusion film formation was carried out in the same manner as in Example 1, and no defective appearance occurred from the start of operation to 8 hours later. Had many vertical stripes in the EVOH layer.

G. Effect of the Invention According to the present invention, it is possible to obtain a multilayer laminate having an extremely good appearance, and at the time of continuous melt molding for a long time, sometimes the appearance does not deteriorate over time, and the appearance is always good. A multi-layer laminate can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the results of measuring the relationship between the heating time and the discharge rate using a Koka type flow tester. The position of each point in the figure is as follows: A point: 15 minutes later C point: 2 hours later B point: 1.75 hours later (point at which discharge speed is the lowest value between A and C) D point: 5 hours later.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Oyan, 1621 Sakata, Kurashiki-shi, Okayama Claret Co., Ltd. Yurika Ashihara (56) References JP 62-143954 (JP, A) JP 62 -15246 (JP, A) JP-A-57-205147 (JP, A) Actually developed 50-89701 (JP, U) JP-B 57-14381 (JP, B2)

Claims (10)

(57) [Claims] 1. A laminate of an ethylene-vinyl alcohol copolymer layer and a hydrophobic thermoplastic resin layer, which has a melting point of 10 to 80 from the melting point of the ethylene-vinyl alcohol copolymer in a Koka type flow tester. In the relationship between the heating time and the discharge speed at at least one point at a temperature higher by ℃,
The discharge speed does not increase substantially until 15 minutes, and after 15 minutes 2
The discharge rate at any heating time within 1 hour is 1/10 to 50 times the discharge rate after 15 minutes, and after 2 hours
It is recommended to use an ethylene-vinyl alcohol copolymer that exhibits flow characteristics such that the discharge rate at any heating time within 10 hours is at least once within the range of 2 to 50 times the discharge rate after 15 minutes. Characteristic laminate. 2. An ethylene-vinyl alcohol-based copolymer is obtained after 15 minutes in the relationship between the heating time and the discharge rate at the heat-melt molding temperature of the ethylene-vinyl alcohol-based copolymer in a Koka type flow tester. The laminate according to claim 1, which exhibits flow characteristics that are 1/5 or more and 1 or less of the discharge speed at 0 minute. 3. An ethylene-vinyl alcohol copolymer,
In the relationship between the heating time and the discharge rate at the heating and melt molding temperature of the ethylene-vinyl alcohol copolymer in the high-performance flow tester, the flow rate characteristic that the discharge rate within 2 hours to 10 hours increases within this time is shown. The laminated body according to claim 1, which is shown. 4. The hydrophobic thermoplastic resin is a homopolymer or copolymer of polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, thermoplastic polyester, polyamide, polystyrene, polyvinyl chloride, polycarbonate. The laminate according to claim 1, which is at least one kind of resin selected. 5. A laminate obtained by laminating an ethylene-vinyl alcohol copolymer layer and a hydrophobic thermoplastic resin layer via an ethylenically unsaturated carboxylic acid or a thermoplastic resin modified with the carboxylic acid anhydride. In a chemical flow tester, the discharge rate is substantially up to at least 15 minutes in the relationship between the heating time and the discharge rate at at least one point at a temperature 10 to 80 ° C. higher than the melting point of the ethylene-vinyl alcohol copolymer. It does not increase, and the discharge speed at any heating time within 15 hours after 15 minutes is the same as the discharge speed after 15 minutes.
Flow characteristics that are in the range of 1/10 to 50 times, and that the discharge speed at any heating time within 2 hours to 10 hours is at least 2 to 50 times the discharge speed after 15 minutes. The laminated body characterized by using the ethylene-vinyl alcohol type copolymer shown in FIG. 6. An ethylene-vinyl alcohol-based copolymer is obtained after 15 minutes in the relationship between the heating time and the discharge rate at the hot melt molding temperature of the ethylene-vinyl alcohol-based copolymer in a Koka type flow tester. The laminate according to claim 5, which exhibits flow characteristics that are 1/5 or more and 1 or less of the discharge speed at 0 minute discharge speed. 7. An ethylene-vinyl alcohol copolymer,
In the relationship between the heating time and the discharge rate at the heating and melt molding temperature of the ethylene-vinyl alcohol copolymer in the high-performance flow tester, the flow rate characteristic that the discharge rate within 2 hours to 10 hours increases within this time is shown. The laminated body according to claim 5, which is shown. 8. The hydrophobic thermoplastic resin is a homopolymer or a copolymer of polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, thermoplastic polyester, polyamide, polystyrene, polyvinyl chloride, and polycarbonate. The laminate according to claim 5, which is at least one kind of resin selected. 9. The method according to claim 5, wherein the thermoplastic resin modified with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride is a modified olefin polymer with an ethylenically unsaturated carboxylic acid or the carboxylic acid anhydride. The laminate described. 10. The laminate according to claim 5, wherein the olefin polymer is selected from ethylene-vinyl acetate copolymer and ethylene-acrylic acid ethyl ester copolymer.