JP2000263712A - Multilayer structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat stability and rapid film forming properties during manufacturing by forming a multilayer structure of an ethylene-vinyl alcohol copolymer having an ethylene content, saponification degree or the like showing each a specific value, a resin composition layer having a specific content of a chemical compound containing a hindered amine group and a paper base material layer. SOLUTION: The ethylene-vinyl alcohol copolymer (EVOH) is obtained by saponifying EVOH. The multilayer structure is formed of a resin composition obtained by adding 0.001-0.5 pts.wt. a compound having a hindered amine group to 100 pts.wt. EVOH with 10-60 mol% ethylene content, 90% or more saponification degree and 300-2,000 degree of viscosityaverage polymerization and a paper base material layer. The compound having the hindered amine group is preferably a piperiding derivative and especially favorably a 2, 2, 6, 6tetraalkylpiperidine derivative having a substituting group at the fourth position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) and a hindered amine group, which are improved in thermal stability (long run property) and high-speed film forming property during production. The present invention relates to a multilayer structure having a resin composition layer composed of a compound having the following and a paper base layer.

[0002]

2. Description of the Related Art EVOH is a useful polymer material having excellent oxygen shielding properties, oil resistance, non-charging properties, mechanical strength, etc., and is widely used as various packaging materials such as films, sheets and containers. When EVOH is used for various types of packaging materials, not only performance for the intended purpose, but also slight coloring and holes on the appearance,
Fish eye, streak, rough skin and transparency are problematic.

[0005] However, EVOH has a problem that coloring, pores, fish eyes, streaks, and rough skin are liable to occur during melt molding. Therefore, conventionally, the following various methods have been proposed as methods for suppressing these problems.

[0004] EVOH is usually obtained by adding a caustic alkali to an ethylene-vinyl acetate copolymer and saponifying it. When the saponified product is melt-molded as it is, it is easily thermally decomposed and the melt viscosity is remarkably lowered. It cannot be used because it is violently colored. Many measures have been taken for this improvement. For example, it is known that the operation can be improved to some extent by washing the EVOH sufficiently with water or immersing it in an acid or an acid solution.
664, JP-A-48-25048, JP-A-51-8
No. 8544, JP-A-51-88545, JP-B-55-88545.
19242 and the like.

[0005] Assuming that the heat stabilizing effect of a certain metal salt is remarkable, the addition of a metal salt to improve the melt formability is also disclosed in JP-A-52-954, JP-A-52-955, and JP-A-52-955. No. 56-41204.

By blending an olefin, a vinyl silane compound copolymerized polyolefin, or the like, it is possible to improve the streak-like flow unevenness by an elastic effect.
97138.

However, EVO using these processing methods
H can improve the film forming property to some extent when formed by ordinary melt extrusion (extrusion temperature: a temperature about 20 ° C. higher than the melting point), but severe conditions for EVOH, that is, 50 ° C. or higher than the melting point of EVOH to be used. When the film is formed at a high temperature, the film is severely deteriorated in the extruder, causing fish eyes and streaks on the film surface, resulting in a poor film appearance, and finally a molded product that can be used cannot be obtained.

In particular, when extrusion coating is performed at a high speed in order to secure productivity, it is necessary to lower the melt viscosity of EVOH in order to reduce the fluctuation width of neck-in.
Therefore, the melt film formation is performed at a high temperature, and the influence of the above-described deterioration of the resin is great. Among them, EVOH on paper base
When coating a molten multilayer body containing, the EVOH layer needs to be formed thinly and uniformly from the viewpoint of cost and required performance, so that a molded article is likely to be defective due to deterioration of the resin.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ethylene-vinyl alcohol copolymer (hereinafter referred to as EV) having improved thermal stability (long run property) during production and high-speed film forming property.
OH) and a resin composition layer comprising a compound having a hindered amine group and a paper base layer.

[0010]

The object of the present invention is to provide an ethylene vinyl alcohol copolymer having an ethylene content of 10 to 60 mol%, a saponification degree of 90% or more, a viscosity average polymerization degree of 300 to 2,000, and a hindered amine. This is achieved by providing a multilayer structure having a resin composition layer composed of 0.001 to 0.5 parts by weight of a compound having a group and a paper base layer. At this time, the thickness of the resin composition layer is 2 to
The case of 30 μm is important.

[0011] Further, under the conditions of a die temperature of 240 ° C or more and a take-up speed of 100 m / min or more, an ethylene content of 10 to 10 m / min.
60 mol%, saponification degree 90% or more, viscosity average polymerization degree 30
0 to 2000 ethylene vinyl alcohol copolymer 10
0 parts by weight and a compound having a hindered amine group
It is also an object of the present invention to provide a method for producing a multilayer structure in which a molten multilayer body containing a resin composition layer composed of 001 to 0.5 parts by weight is co-extrusion coated on a substrate.

In this case, a resin composition comprising 0.01 to 0.5 parts by weight of a boron compound in terms of boric acid (H ₃ BO ₃ ) in addition to the above resin composition is preferred. Further, such a resin composition has an ethylene content of 10 to 60 mol%, a saponification degree of 90% or more, a viscosity average polymerization degree of 300 to 2,000, 100 parts by weight of an ethylene vinyl alcohol copolymer, and a compound having a hindered amine group of 0.001 to 0.001. 0.5% by weight, time required for 1% weight reduction at 250 ° C. under inert gas flow (T1) and ethylene content (Et)
Preferably satisfies the following expression (1). T1 ≧ 7 × Et-170 (1) T1: Time required for 1% weight loss at 250 ° C. (minute) Et: Ethylene content (mol%)

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The EVOH used in the present invention is:
An ethylene-fatty acid vinyl copolymer obtained by saponification and having an ethylene content of 10 to 60 mol%, preferably 20
~ 55 mol%, more preferably 20-50 mol%,
And the saponification degree of the fatty acid vinyl component of the copolymer is 90% or more, preferably 95% or more. Ethylene content of 10
If it is less than mol%, not only the performance of the molded product, such as water resistance and hot water resistance, will be reduced, but also EVOH itself will tend to gel, streaks and fish eyes will be remarkable, and the effects of the present invention will not be easily exhibited. On the other hand, if the ethylene content exceeds 60 mol% or the saponification degree is less than 90%, the gas barrier properties are reduced, and the inherent characteristics of EVOH cannot be maintained.

The viscosity average polymerization degree of the EVOH of the present invention is a value calculated from the intrinsic viscosity measured at a temperature of 30 ° C. using a mixed solvent of phenol / water = 85/15 (weight ratio), and its range is from 300 to 2000. Range. Preferably 50
0 or more, more preferably 700 or more. Degree of polymerization is 30
If it is less than 0, the mechanical strength of the molded body becomes low and the practicality is lacking, and the melt viscosity becomes too low at the time of melt molding at a high temperature, so that it is difficult to form a stable film. It is preferably 1800 or less, more preferably 1500 or less. 2
If it exceeds 000, the melt viscosity becomes too high, and it becomes difficult to perform melt molding, especially when the take-up speed is high, the melt film formation.

Methods for adjusting the degree of polymerization of EVOH include (1) a method of adjusting the degree of polymerization by adjusting the amount of polymerization catalyst and the polymerization temperature during polymerization, and (2) a method of adjusting the degree of polymerization such as vinyltrimethoxysilane during polymerization. And (3) a method of blending and adjusting EVOH having a high degree of polymerization and EVOH having a low degree of polymerization. Also, these methods can be used in combination. Using the above method, an EV having a viscosity average degree of polymerization of 300 to 2,000
OH is obtained.

In addition, other copolymers (eg, propylene, butylene, unsaturated carboxylic acid or its ester (meth) acrylic acid, (meth) acrylic ester, etc.), vinyl, and the like, as long as the object of the present invention is not hindered. Pyrrolidone (such as N-vinylpyrrolidone) can also be used as a copolymer component. In addition, plasticizers, heat stabilizers, UV absorbers, antioxidants, coloring agents, fillers, thickeners,
Blends with other resins (polyamide, partially saponified ethylene-vinyl acetate copolymer, etc.) are also free as long as the effects of the present invention are not impaired.

Hereinafter, the method for producing EVOH of the present invention will be described in detail. The polymerization of ethylene and vinyl ester may be any of solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, and may be any of continuous type and batch type. The polymerization conditions in this case are as follows.

Solvent: Alcohols are preferable, but other organic solvents (such as dimethyl sulfoxide) which can dissolve ethylene, vinyl ester and ethylene vinyl ester copolymer can also be used. As the alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.

Catalyst: 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methyl-2,
4-dimethylvaleronitrile), 2,2'-azobis-
Azonitrile initiators such as (2-cyclopropylpropionitrile) and isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate, di-n-propylperoxydicarbonate, t-butylperoxyneo Decanoate, lauroyl peroxide, benzoyl peroxide,
Organic peroxide-based initiators such as t-butyl hydroperoxide and the like can be used. Temperature: 20-90 ° C, preferably 40-70 ° C. Time; 2 to 15 hours, preferably 3 to 11 hours. Polymerization rate; 10 to 90% based on the charged vinyl ester;
Preferably 30-80%. Resin content in solution after polymerization; 5 to 85%, preferably 20
~ 70%. Ethylene content in the copolymer: 20 to 60 mol%, preferably 25 to 55 mol%.

In addition to ethylene and vinyl esters, monomers copolymerizable therewith, for example, propylene, butylene, unsaturated carboxylic acids or esters thereof (meth)
Vinylpyrrolidone (such as N-vinylpyrrolidone) such as acrylic acid and (meth) acrylic acid ester (methyl, ethyl) can also be used as a copolymerization component.

After the polymerization for a predetermined time, when a predetermined polymerization rate is reached, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation. As a method of driving out unreacted vinyl ester from the ethylene vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously supplied at a constant rate from the upper part of a tower filled with Raschig rings, and A method in which an organic solvent vapor such as methanol is blown in, a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester flows out from the top of the tower, and the copolymer solution from which unreacted vinyl ester is removed is taken out from the bottom of the tower. Is done.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester component in the copolymer. The saponification method can be either a continuous type or a batch type. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate and the like are used. For example, the saponification conditions in the case of the batch system are as follows. Concentration of the copolymer solution; 10 to 50%. Reaction temperature; Amount of catalyst used: 0.02 to 0.6 equivalent (per vinyl ester component). Time; 1-6 hours. The saponification degree can be arbitrarily adjusted depending on the conditions.

The EVOH after the reaction contains an alkali catalyst, by-product salts, other impurities, etc., and is neutralized as necessary, and then removed by washing. E obtained
Acids such as phosphoric acid, pyrophosphoric acid, phosphorous acid, oxalic acid, succinic acid, adipic acid, tartaric acid, citric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, acetic acid or polybasic acids and salts thereof to VOH It is also possible to add.

Among them, a method in which EVOH is immersed in a solution of the above compound is desirable in order to exert the effects of the present invention more remarkably. This processing can be performed by either a batch method or a continuous method. In this case, the shape of the saponified product may be any shape such as powder, granule, sphere, and columnar chip.

The resin composition of the present invention contains a compound having a hindered amine group in an amount of 0.1 to 100 parts by weight of EVOH.
001 to 0.5 parts by weight. Thereby, long-time operation is possible even in the melt film formation under high temperature and high speed conditions, and a molded article having a good appearance can be obtained.

The compound having a hindered amine group is preferably a piperidine derivative, particularly preferably a 2,2,6,6-tetraalkylpiperidine derivative having a substituent at the 4-position. Examples of the substituent at the 4-position include a carboxyl group, an alkoxy group, and an alkylamino group. Examples of the compound having such a hindered amine group include the compounds represented by the following formulas (1) to (16). Although an alkyl group may be substituted at the N-position, it is preferable to use one having a hydrogen atom bonded thereto because of its excellent heat stabilizing effect. Furthermore, molecular weight 2
It is preferably at least 50, more preferably at least 300, from the viewpoint of maintaining thermal stability during melt-kneading.

[0027]

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[0028]

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[0029]

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[0030]

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[0032]

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[0033]

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[0034]

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[0035]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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The amount of the compound having a hindered amine group is 0.001 to 0.5 with respect to 100 parts by weight of EVOH.
Parts by weight, preferably 0.01 to 0.3 parts by weight, more preferably 0.01 to 0.1 parts by weight. If it is added in an amount of 0.5 part by weight or more, it is severely colored in the extruder and cannot be used. On the other hand, if the amount is less than 0.001 part by weight, the object of the present invention cannot be achieved. These compounds having a hindered amine group may be used alone or in combination of two or more.

The method for incorporating a compound having a hindered amine group is not particularly limited. For example, a method of immersing the saponified product in a solution in which the compound is dissolved, a method of melting the saponified product and mixing the compound, and a method of dissolving the saponified product in an appropriate solvent and mixing the compound And a method of melt-blending in an extruder. Among them, a method in which EVOH and a compound having a hindered amine group are melt-blended is desirable in that it is simpler.

Further, it is preferable that the resin composition of the present invention contains a boron compound because the thermal stability, particularly the long-run property at high temperatures, can be further improved. The content of the boron compound is 0.01 to 0.5 part by weight, preferably 0.05 to 0.3 part by weight, most preferably, in terms of boric acid (H ₃ BO ₃ ) based on 100 parts by weight of EVOH. 0.07
０．２0.2 parts by weight. In the present invention, when the boron compound used is other than boric acid, the content is determined by converting the boron content to the boric acid (H ₃ BO ₃ ) content.

As the boron compound used in the present invention, boric acid derivatives such as boric acid, borate esters and borates are preferably used. Examples of boric acid include orthoboric acid, metaboric acid, tetraboric acid, and the like, and borate salts include sodium metaborate, sodium tetraborate, sodium pentaborate, borax, lithium borate, potassium borate, and the like. No. Examples of the borate ester include triethyl borate and trimethyl borate. Of these, orthoboric acid (simply referred to as boric acid), borax and their derivatives are preferred because they have large effects and are inexpensive.

The method for incorporating the boron compound into the resin composition is not particularly limited. For example, a method of immersing the saponified product in a solution in which the boron compound is dissolved, a method of melting the saponified product and mixing the boron compound, a method of dissolving the saponified product in an appropriate solvent and mixing the boron compound Etc.

When EVOH is immersed in a solution containing a boron compound, the concentration of the boron compound in the solution is not particularly limited. The solvent of the solution is not particularly limited, but is preferably an aqueous solution for reasons such as handling. It is desirable that the weight of the solution when the saponified product is immersed is at least three times, preferably at least 20 times the weight of the saponified product when dried. The preferred range of the immersion time varies depending on the form of the EVOH, but in the case of a chip of about 1 to 10 mm, the immersion time is preferably 1 hour or more, preferably 2 hours or more.

The relationship between the time (T1) required for the resin composition of the present invention to lose 1% of weight at 250 ° C. under an inert gas stream (T1) and the ethylene content (Et) satisfies the following formula (1). This is also preferable in that the high-temperature thermal stability is improved. T1 ≧ 7 × Et-170 (1) T1: Time required for 1% weight reduction at 250 ° C. (minute) Et: Ethylene content (mol%) It is more preferable to satisfy the expression (1 ′). . T1 ≧ 10 × Et-170 (1 ′)

The resin composition of the present invention may contain a thermoplastic resin other than EVOH as long as the effects of the present invention are not impaired. As the thermoplastic resin, various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene propylene copolymer, copolymer of ethylene and α-olefin having 4 or more carbon atoms, polyolefin and Copolymers with maleic anhydride, ethylene vinyl ester copolymers, ethylene acrylate ester copolymers, or modified polyolefins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or derivatives thereof, and various nylons (nylon 6 , Nylon 66, nylon 6/66 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin. It is also possible to blend EVOHs having different degrees of polymerization, ethylene content and saponification degree and melt-mold them.

In the resin composition, various plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, slip agents, antistatic agents, drying agents, crosslinking agents, metal salts, fillers, various fibers, etc. It is also possible to add an appropriate amount of a reinforcing agent or the like.

The obtained resin composition is formed into various molded products such as films, sheets, containers, pipes and fibers by melt molding. At this time, these molded products can be pulverized and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers and the like. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding.

In particular, the resin composition of the present invention is preferably used for extrusion coating. In such extrusion coating molding, it is often desired to form a film at a high speed from the viewpoint of improving production efficiency. Therefore, in order to prevent neck-in, a melt film is formed at a higher temperature than usual. In such a case, it is preferable to use the resin composition of the present invention which is excellent in thermal stability and high-speed film-forming property.

Among the extrusion coating methods, a method of co-extrusion coating a molten multilayer body containing a resin composition layer on a substrate is preferred for the following reasons. That is, since the EVOH resin is generally more expensive than a general-purpose resin such as polyolefin, the resin composition layer of the present invention can be thinned by co-extrusion coating. Lamination with an adhesive resin (hereinafter sometimes abbreviated as AD) for ensuring adhesion to the substrate, particularly an adhesive resin layer made of a carboxylic acid-modified polyolefin or a hydrophobic resin layer for preventing the resin composition from absorbing moisture. The composition can also be formed in a single coating operation. Furthermore, by extruding simultaneously with a resin such as polyolefin which is easily extruded, it is often possible to form a more stable film than coating with a single layer of the resin composition.

The carboxylic acid-modified polyolefin to be coextruded with EVOH is a polyolefin having a carboxyl group in the molecule, and the polyolefin is graft-modified with an α, β-unsaturated carboxylic acid or an anhydride thereof. And those obtained by random copolymerization of an olefin monomer and an α, β-unsaturated carboxylic acid or anhydride thereof. Examples of the α, β-unsaturated carboxylic acid or its anhydride include acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, and itaconic anhydride, and maleic anhydride is preferred.

The carboxylic acid-modified polyolefin has a density of from 0.88 to 0.94 g / cm ³ , preferably from 0.90 to 0.93 g / cm ³ , more preferably from 0.90 to 0.93 g / cm ³ .
Carboxylic acid-modified polyethylene of 5 to 0.92 g / cm ³ is preferred. Representative examples of such carboxylic acid-modified polyethylene include those using low-density polyethylene produced by a high-pressure method or linear low-density polyethylene (LLDPE) produced by a low-pressure method using a Ziegler-type catalyst as a base resin. Of these, those using LLDPE as a base resin are preferred from the viewpoint of film forming properties.

The carboxylic acid-modified polyolefin has a melt index (at 190 ° C. under a load of 2160 g) of 3
１５15 g / 10 min. It is preferably at most 12 g / 10 min, more preferably at most 10 g / 10 min. It is preferably at least 4 g / 10 min, more preferably at least 6 g / 10 min. This is because when there is no difference between the EVOH and the melt index that are coextruded at the same time, unevenness of the interface is less likely to occur, and a molded article with good appearance can be obtained.

The melt molding temperature of the resin composition of the present invention varies depending on the melting point of the copolymer, the molding method, and the like, and is not particularly limited. The die temperature is preferably 240 ° C. or higher from the viewpoint that the properties can be further exhibited. More preferably at least 250 ° C., even more preferably at 260 ° C.
° C or higher. The take-up speed at the time of extrusion coating is preferably 200 m / min or more from the viewpoint that the effect of the present invention of high-speed film formation stability can be efficiently exhibited. More preferably, it is 250 m / min, even more preferably 300 m / min.

The structure of the multilayer structure produced using the resin composition of the present invention is not particularly limited, but may be paper,
A configuration in which a substrate such as a plastic film or a metal foil is coated and laminated is preferable. Especially paper substrate
Since the resin composition itself cannot be melt-molded and has no gas barrier properties, it is most useful for extrusion coating and molding the resin composition of the present invention. The paper substrate to be coated may be one in which a resin such as low-density polyethylene (hereinafter sometimes abbreviated as LDPE) or the like is already coated on both surfaces or one surface thereof on the paper substrate.

The layer structure of the multilayer structure obtained by co-extrusion coating the thus obtained molten multilayer comprising an EVOH layer and a carboxylic acid-modified polyolefin layer on a substrate is not particularly limited. The following configuration is preferable. here,
The carboxylic acid-modified polyolefin layer was indicated as AD, and the thermoplastic resin layer was indicated as TR.

Inner layer: AD / EVOH / AD / substrate: outer layer Inner layer: TR / AD / EVOH / AD / TR / substrate / T
R: outer layer inner layer: TR / AD / EVOH / AD / TR / TR / substrate / TR: outer layer inner layer: EVOH / AD / TR / substrate / TR: outer layer inner layer: TR / AD / EVOH / substrate / TR: Outer layer Inner layer: EVOH / AD / TR / AD / EVOH / AD /
TR / substrate / TR: outer layer Inner layer: TR / AD / EVOH / AD / substrate / TR: outer layer Inner layer: AD / EVOH / AD / substrate / TR: outer layer

The thermoplastic resin represented by TR in the above examples is not particularly limited, and different types of thermoplastic resins may be used in one multilayer structure. The most typical thermoplastic resin is polyolefin, especially polyethylene, especially having a density of 0.88 to 0.94 g / cm.
³ , preferably 0.90 to 0.93 g / cm ³ , more preferably 0.905 to 0.92 g / cm ³ polyethylene is important in the present invention. Such polyethylene is useful in terms of moisture resistance, heat sealability, flexibility, and low cost. Representative examples of such polyethylene include low-density polyethylene produced by a high-pressure method and linear low-density polyethylene (LLDPE) produced by a low-pressure method using a Ziegler-type catalyst.
E is preferred from the viewpoint of film forming properties.

In addition, the EVO in the multilayer structure of the present invention
The thickness of the H layer is 2 to 30 μm. If it is less than 2 μm, it is difficult to prevent the generation of pinholes under high-speed film forming conditions. More preferably, it is 3 μm or more. Conversely 3
If it exceeds 0 μm, the material cost increases and the appearance of the surface of the molded product deteriorates. It is more preferably at most 15 μm, even more preferably at most 8 μm.

The multilayer structure containing the paper base material thus obtained is processed into a shape such as a carton or a cup and used as various paper containers. Such a paper container can store various beverages and the like for a long period of time.

[0065]

The composition of the present invention will be described in more detail with reference to the following examples. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.

The time required for 1% weight loss at 250 ° C. The time required for 1% weight loss at 250 ° C. was measured using a differential thermogravimetric analyzer (TG / DTA 220) manufactured by Seiko Instruments Inc. Thermogravimetry was performed according to JIS K7120. The specimen weight is 6-9mg,
The inflow gas was 100 ml / min of nitrogen. Heating rate 10
After the temperature was raised to 250 ° C, the temperature was kept at 250 ° C. The TG curve is based on JIS, with the vertical axis representing mass and the horizontal axis representing time.
It measured by the method according to K7120. Vacuum dry before measurement to remove the effect of moisture on the sample, and volatile matter 0.1%
It was as follows. After the start of the measurement, the time (T1) at which the weight decreased by 1% from the weight before the measurement was read.

Viscosity average degree of polymerization 30 ° C., aqueous phenol solution ｛phenol / water = 85 /
15 (weight ratio) Mark-Houwink-S from the value of intrinsic viscosity measured in {circle around (1)} and the value of ethylene content of the sample.
It was calculated using akurada equation (2). Pv = ([η] / k) ^{1 / α} (2) where k = 1.3 × 10 ⁽⁻³⁾ · exp (−0.13 × Et) α = 0.65-0.059 (Et −0.2) where [η] is the intrinsic viscosity (dl) measured at 30 ° C. in a water-containing phenol solution {phenol / water = 85/15 (weight ratio)}.
/ G) Et: ethylene content (mol% × 1/100)

Determination of Boron Compound 100 g of a dry chip as a sample was placed in a magnetic crucible and incinerated in an electric furnace. The obtained ash is dissolved in 200 mL of a 0.01 N aqueous nitric acid solution, the content of boron is quantified by atomic absorption analysis, and the content of the boron compound is converted into boric acid (H ₃ BO ₃ ) from the content of boron. It was converted to a value.

Melt Index (MI) Measured under the conditions of a temperature of 190 ° C. and a load of 2160 g using a melt indexer according to ASTM-D1238. In the present invention, with respect to EVOH having a melting point higher than around 190 ° C., a load of 2
A value measured at 160 g and extrapolated to a temperature of 190 ° C. is used.

Extrusion film-forming test A dry chip as a sample was extrusion-coated on a carton paper (thickness: about 500 μm, basis weight: 40 g / m ² ) at a die temperature of 240 ° C. Film formation was performed continuously for 8 hours from the start of molding, and fish eyes and streaks were visually determined. The specifications of the extruder are as follows. Model Single screw extruder (non-vented type) L / D 26 Bore 40mmφ Screw Single full flight type, Surface nitrided steel Rotation speed 40rpm Motor capacity DC7.5KW (Rated 45A) Heater 4 split type Die width 300mm Die resin temperature 240 ° C Take-off speed 10 m / min Fisheye and streak occurrence were determined as follows. A: No fisheye or streak was observed. B: Faint fish eyes and streaks were confirmed. C: Clear fish eyes and streaks were confirmed. D: Many fish eyes and streaks were confirmed.

Coextrusion coating test Carton paper (thickness 500 μm, basis weight 40 g /
m ² ), the carton paper was subjected to co-extrusion coating of three types and five layers of co-extrusion. The configuration of the co-extrusion coat portion is low density polyethylene / adhesive layer / EVOH / adhesive layer / low density polyethylene, and the thickness configuration is 20/5/5/5 / 20μ.
m. An extruder for low-density polyethylene, an extruder for EVOH, an extruder for an adhesive layer, and a feed block and a T-die for joining and distributing resins supplied from the respective extruders were used. As the low-density polyethylene, linear low-density polyethylene (Mitsui Chemicals Co., Ltd. Ultzex 2022)
L) and maleic anhydride-modified polypropylene (Mitsui Petrochemical Industries ADMER QF
-500) was used. The temperature conditions of the co-extrusion coat are feed block, die 250 ° C, take-off speed 300
m / min. The appearance of the film was visually observed and determined as follows. A: No fisheye or streak was observed. B: Faint fish eyes and streaks were confirmed. C: Clear fish eyes and streaks were confirmed. D: Many fish eyes and streaks were confirmed.

Example 1 Vinyl acetate 1960 was placed in a polymerization tank having a pressure resistance of 100 kg / cm ^2.
0 parts, 2180 parts of methanol and 7.5 parts of AIBN (azobisisobutyronitrile) were charged and replaced with nitrogen while stirring, then the temperature was raised and the pressure was raised to an internal temperature of 60 ° C and an ethylene pressure of 35.
It was adjusted to 5 kg / cm ² . After maintaining the temperature and pressure for 3.5 hours for polymerization, 5 parts of hydroquinone was added,
The polymerization tank was returned to normal pressure, and ethylene was removed by evaporation. Subsequently, this methanol solution was continuously allowed to flow down from the top of the effluent tower filled with Raschig rings, while methanol vapor was blown in from the bottom of the tower to release unreacted vinyl acetate monomer from the top of the tower together with methanol vapor, and passed through a condenser. By removing, 45% of ethylene vinyl acetate copolymer of 0.01% or less unreacted vinyl acetate
A methanol solution was obtained. At this time, the polymerization rate was 47% based on the charged vinyl acetate, and the ethylene content was 44 mol%.

Next, a methanol solution of an ethylene-vinyl acetate copolymer was charged into a saponification reactor, and a caustic soda / methanol solution (80 g / L) became 0.4 equivalent to the vinyl acetate component in the copolymer. , And methanol was added to adjust the copolymer concentration to 20%. The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. After that, the reaction is stopped by neutralizing with acetic acid, extruded into water from a metal plate having a circular opening, precipitated, and cut to obtain a diameter of about 3 mm and a length of about 5 m.
m chips were obtained. The obtained chips were subjected to liquid removal by a centrifugal separator, and a large amount of water was added thereto to repeat washing and liquid removal.

300 g of these pellets were dispersed in 0.5 L of water, and 0.2 g / L of boric acid, 0.1 g / L of acetic acid, and 0.3 g / L of potassium dihydrogen phosphate were added, followed by stirring for 4 hours. . Thereafter, the obtained pellet was taken out, centrifuged, and dried with hot air at 105 ° C. After drying, the boric acid content in the pellets was 0.05 wt%, MI 8.0 g
/ 10 minutes, and the viscosity average degree of polymerization was 640. The resulting pellets had an ethylene content of 44 mol% and a degree of saponification of 9
It was 9.6%.

The above-mentioned hindered amine (2) was added to the pellets in an amount of 500 ppm, and a melt extrusion test was conducted. The MI of the pellet was 8.0 g / 10 min. The time required for 1% weight loss at 250 ° C. was 150 minutes. In the single-layer film forming test, the film appearance was very good. As a result of the co-extrusion coating, the neck-in was small and good.

Examples 2 to 8, Comparative Examples 1 to 6 Coextrusion coating test was carried out in the same manner as in Example 1 except that the resin compositions shown in Table 1 were used instead of the resin compositions used in Example 1. And evaluated. The results are summarized in Table 1.

[0077]

[Table 1]

[0078]

According to the present invention, a resin comprising a compound having an EVOH and a hindered amine group, which has reduced thermal degradation in an extruder, and has improved thermal stability (long run property) and high-speed film forming property during production. A multilayer structure having a good appearance and having a composition layer and a paper base layer is provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4F100 AA01A AH03A AH07A AK03C AK06 AK62C AK66C AK69A AL07C BA02 BA03 BA04 BA05 BA07 BA10A BA10B BA13 CB00 DG10B EH202 EH232 GB16 GB23 JA07A JA20 EU1J01 EUB 012 GF00 GG01 GK01

Claims (6)

[Claims] A compound having a hindered amine group of 100 parts by weight of an ethylene vinyl alcohol copolymer having an ethylene content of 10 to 60 mol%, a saponification degree of 90% or more, and a viscosity average polymerization degree of 300 to 2,000. A multilayer structure having a resin composition layer consisting of 5 parts by weight and a paper base layer. 2. The multilayer structure according to claim 1, wherein the thickness of the resin composition layer is 2 to 30 μm. 3. An ethylene content of 10 to 60 at a die temperature of 240 ° C. or higher and a take-up speed of 100 m / min or higher.
Mol%, saponification degree 90% or more, viscosity average polymerization degree 300 to
2000 parts by weight of an ethylene vinyl alcohol copolymer and a compound having a hindered amine group of 0.00
A method for producing a multilayer structure, comprising co-extrusion coating a molten multilayer body containing a resin composition layer consisting of 1 to 0.5 parts by weight on a substrate. 4. 100 parts by weight of an ethylene vinyl alcohol copolymer having an ethylene content of 10 to 60 mol%, a saponification degree of 90% or more, and a viscosity average polymerization degree of 300 to 2,000, and a compound having a hindered amine group of 0.001 to 0.1. 5 parts by weight of boric acid (H ₃ BO ₃₎ consisting of a boron compound of 0.01 to 0.5 parts by weight in terms of resin composition. 5. 100 parts by weight of an ethylene vinyl alcohol copolymer having an ethylene content of 10 to 60 mol%, a saponification degree of 90% or more, a viscosity average polymerization degree of 300 to 2,000, and a compound having a hindered amine group of 0.001 to 0. 5 parts by weight, the time required for a 1% weight loss at 250 ° C. under an inert gas stream (T1) and the ethylene content (E
A resin composition in which the relationship of t) satisfies the following formula (1). T1 ≧ 7 × Et-170 (1) T1: Time required for 1% weight loss at 250 ° C. (minute) Et: Ethylene content (mol%) 6. The resin composition according to claim 4, which is for extrusion coating.