CN115477803B

CN115477803B - Ethylene-vinyl alcohol copolymer resin particle composition, ethylene-vinyl alcohol copolymer film formed therefrom, and multilayer structure

Info

Publication number: CN115477803B
Application number: CN202210691641.0A
Authority: CN
Inventors: 梁志杰; 林文星
Original assignee: Chang Chun Petrochemical Co Ltd
Current assignee: Chang Chun Petrochemical Co Ltd
Priority date: 2021-06-16
Filing date: 2022-06-16
Publication date: 2024-11-12
Anticipated expiration: 2042-06-16
Also published as: CN115477803A; CN115477805A; CN115477804B; CN115477804A; CN115477805B

Abstract

The present invention relates to an ethylene-vinyl alcohol copolymer (EVOH) resin pellet composition, an ethylene-vinyl alcohol copolymer film formed therefrom, and a multilayer structure comprising the same. The EVOH resin pellet composition comprises first EVOH resin pellets having a surface peak portion solid volume (Vmp) of 0.00001-6 um ³/um²; and second EVOH resin particles having a surface peak portion solid volume (Vmp) of 0.00015 to 20 μm ³/um². The invention can improve the processability and mechanical properties of EVOH composition when it is made into film.

Description

Ethylene-vinyl alcohol copolymer resin pellet composition, ethylene-vinyl alcohol copolymer film formed therefrom, and multilayer structure

Technical Field

The present invention relates to an ethylene-vinyl alcohol (EVOH) composition; in particular, it relates to an ethylene-vinyl alcohol copolymer resin pellet composition, a film and a multilayer structure formed from the EVOH resin pellet composition.

Background

EVOH resins are widely used in multilayer bodies for preserving perishable items. For example, EVOH resins and multilayers made therefrom are commonly used in the food packaging industry, medical equipment and consumable industry, pharmaceutical industry, electronics industry, and agrochemical industry. Specifically, EVOH resins are generally used in the form of films; for example: it can be used to add to a multilayer body as a unique layer to act as an oxygen barrier.

In practice, the film made of the EVOH material generally has various requirements for its processability, mechanical properties, heat resistance and the like. For example: after the EVOH film is formed, a large amount of Gel particles (Gel, also called fish eyes) are not formed on the surface of the EVOH film, so that the EVOH film has excellent processing performance; also, EVOH films may be said to have desirable mechanical properties when they are stretched at a particular tensile force.

Disclosure of Invention

However, a concept or means for effectively satisfying the above requirements has never been proposed in the prior art. In view of the above, the present inventors have found that when two types of EVOH resin pellets contained in an EVOH resin pellet composition each have a specific surface peak portion physical volume (Vmp) value range, a film formed from the EVOH resin pellet composition can have good processability and mechanical properties.

Accordingly, in one aspect, the present invention provides an ethylene vinyl alcohol copolymer (ETHYLENE VINYL alcohol copolymer, EVOH) resin pellet composition comprising: the first EVOH resin pellet has a surface peak portion solid volume (Vmp) of 0.00001-6 um ³/um², and the second EVOH resin pellet has a surface peak portion solid volume (Vmp) of 0.00015-20 um ³/um².

According to some embodiments of the invention, the Vmp of the second EVOH resin particles is greater than the Vmp of the first EVOH resin particles.

According to some embodiments of the invention, the first EVOH resin particles have a melting point of 135-179 ℃, and wherein the second EVOH resin particles have a melting point of 180-198 ℃.

According to some embodiments of the invention, the first EVOH resin particles have an ethylene content of 36 to 50 mole percent.

According to some embodiments of the invention, the ethylene content of the second EVOH resin particles is 20 to 35 mole percent.

According to some embodiments of the invention, the EVOH resin pellets are cylindrical, oval, angular, spherical, oval or weichi in shape, and have a long diameter/height of 1 to 5mm and a short diameter of 1 to 5mm.

According to some embodiments of the invention, the weight percentage of the first EVOH resin pellets to the second EVOH resin pellets is 5:95 to 75:25.

According to some embodiments of the invention, the EVOH resin pellet composition has a boron content of 5 to 550ppm.

According to some embodiments of the invention, the EVOH resin pellet composition has an alkali metal content of 10 to 550ppm.

According to some embodiments of the invention, the first EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0020 to 25; and the second EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0070 to 111.

According to some embodiments of the invention, the first EVOH resin particles have a surface parameter of a surface maximum peak height (Sp) of 0.0005 to 29 um; and the second EVOH resin particles have a surface parameter of 0.0020 to 63 μm in a surface maximum peak height (Sp).

According to some embodiments of the invention, the first EVOH resin particles have a protruding peak height (Spk) surface parameter of 0.001 to 2 um; and the second EVOH resin particles have a protruding peak height (Spk) surface parameter of 0.003 to 22 um.

According to some embodiments of the invention, the first EVOH resin particles have a pole height (Sxp) surface parameter of 0.001 to 12 um; and the second EVOH resin particles have a pole height (Sxp) surface parameter of 0.002 to 48 um.

According to some embodiments of the invention, the first EVOH resin particles have a linear arithmetic mean height (Ra) surface parameter of 0.001 to 0.990 um; and the second EVOH resin particles have a linear arithmetic average height (Ra) surface parameter of 0.001 to 0.990 um.

According to some embodiments of the invention, the first EVOH resin particles have a line maximum height (Rz) surface parameter of 0.001 to 9.900 um; and the second EVOH resin particles have a line maximum height (Rz) surface parameter of 0.001 to 9.900 um.

In another aspect, the present invention provides an ethylene-vinyl alcohol copolymer film formed from the EVOH resin pellet composition described above.

In yet another aspect, the present invention provides a multi-layer structure comprising: (a) At least one layer of an ethylene-vinyl alcohol copolymer film formed from the EVOH resin pellet composition; (b) at least one polymer layer; and (c) at least one adhesive layer.

According to some embodiments of the invention, the polymer layer is selected from the group consisting of a low density polyethylene layer, a polyethylene grafted maleic anhydride (polyethylene GRAFTED MALEIC ANHYDRIDE) layer, a polypropylene layer, and a nylon layer, and the adhesive layer is a tie layer.

According to some embodiments of the invention, the multilayer structure is a polymer layer/adhesive layer/ethylene vinyl alcohol copolymer film/adhesive layer/polymer layer.

The ethylene-vinyl alcohol copolymer (ETHYLENE VINYL alcohol copolymer, EVOH) resin pellet composition, the ethylene-vinyl alcohol copolymer film formed by the ethylene-vinyl alcohol copolymer resin pellet composition and the multilayer structure containing the film can enable films formed by the EVOH resin pellet composition to have good processability and mechanical properties without being limited by a specific theory.

Drawings

Embodiments of the present technology will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic illustration of a physical volume of a surface peak portion applied in accordance with the present invention.

It should be understood that aspects of the invention are not limited to the arrangements, instrumentality, and characteristic shown in the attached drawings.

Detailed Description

One aspect of the present invention relates to an ethylene vinyl alcohol copolymer (ETHYLENE VINYL alcohol copolymer, EVOH) resin pellet composition comprising: the first EVOH resin pellet has a surface peak bulk volume (Vmp) of 0.00001 to 6um ³/um², and the second EVOH resin pellet has a surface peak bulk volume (Vmp) of 0.00015 to 20um ³/um².

As used herein, the term surface peak bulk volume (Vmp) refers to the bulk volume of the load area rate p%, the specific definition of which can be referred to ISO 25178. In addition, the size of the core, protruding peak, protruding trough can also be quantified in terms of volume parameters. As shown in fig. 1, vmp represents the volume of the protruding crest portion, vmc represents the volume of the core portion, vvc represents the volume of the core portion space, vvv represents the load area ratio of the protruding trough portion, and 10% to 80% of the section of the core portion is designated in the example preset of fig. 1. The first EVOH resin pellet has a Vmp of 0.00001 to 6um ³/um², for example: 0.00001, 0.00005, 0.00100, 0.00200, 0.00500, 0.01000, 0.05000, 0.10000, 0.50000, 1, 2, 3, 4, 5, or 6um ³/um². The second EVOH resin pellet has a Vmp of 0.00015 to 20um ³/um², for example: 0.00015, 0.00050, 0.01000, 0.05000, 0.10000, 0.50000, 1, 5, 10, 15, or 20um ³/um². According to a preferred embodiment of the present invention, the Vmp of the second EVOH resin particles is greater than the Vmp of the first EVOH resin particles.

According to some embodiments of the invention, the first EVOH resin particles have a melting point of 135 to 179 ℃, for example: 135. 140, 145, 150, 155, 160, 165, 170, 175, or 179 ℃. On the other hand, the second EVOH resin particles have a melting point of 180 to 198 ℃, for example: 180. 182, 184, 186, 188, 190, 192, 194, 196 or 198 ℃.

According to some embodiments of the invention, the ethylene content of the first EVOH resin particles may be about 36 to 50mole percent (mole%), for example: 36. 38, 40, 42, 44, 46, 48, or 50mole%. On the other hand, the ethylene content of the second EVOH resin pellets is 20 to 35mole%, for example: 20. 21, 23, 25, 27, 29, 31, 33, or 35 mole%.

In addition, the saponification degree of the EVOH may be 90mole% or more, preferably 95 mole% or more, more preferably 97mole% or more, and most preferably 99.5mole% or more.

EVOH pellets as used herein refers to forms and/or shapes of EVOH resin pelletized to form one or more pellets, although the pelletization is described throughout this disclosure to form one or more EVOH pellets, the EVOH pellets may be processed into the form of beads, cubes, chips, shavings, etc.; according to some embodiments of the present invention, the EVOH resin pellets are cylindrical, oval, angular, round, oval, or go-like in shape and have a length or height of 1 to 5mm, for example: 1.2, 3, 4 or 5mm; and the short diameter is 1-5 mm, for example: 1.2, 3, 4 or 5mm. As used herein, by "major diameter/height" is meant the longest outer diameter that an object having a surface formed by a closed curved surface has; the term "short diameter" refers to the smallest diameter in a cross section perpendicular to the long diameter or the high diameter and having the largest area. As used herein, the term "object having a surface formed by a closed curved surface" is understood to mean an object having a surface entirely formed by a curved surface; an object formed by the intersection of a plurality of facets without edges; or an object with a cross section which is not rectangular at any position.

Specifically, when the EVOH resin pellet is cylindrical or elliptic cylindrical, the height thereof is in the range of 1 to 5mm, for example ：1.5～5.0mm、1.7～5.0mm、2.2～5.0mm、2.4～5.0mm、 2.6～5.0mm、2.8～5.0mm、3.0～5.0mm、3.2～5.0mm、3.4～5.0mm、3.6～5.0mm、 3.8～5.0mm、4.0～5.0mm、1.7～4.5mm、1.7～4.4mm、1.7～4.2mm、1.7～4.0mm、 1.7～3.8mm、1.7～3.6mm、1.7～3.4mm、1.7～3.2mm、1.7～3.0mm; and the minor diameter thereof is in the range of 1 to 5mm, for example ：1.5～5.0mm、1.7～5.0mm、2.2～5.0mm、2.4～5.0mm、 2.6～5.0mm、2.8～5.0mm、3.0～5.0mm、3.2～5.0mm、3.4～5.0mm、3.6～5.0mm、 3.8～5.0mm、4.0～5.0mm、1.7～4.5mm、1.7～4.4mm、1.7～4.2mm、1.7～4.0mm、 1.7～3.8mm、1.7～3.6mm、1.7～3.4mm、1.7～3.2mm、1.7～3.0mm.

When the EVOH pellets are in the form of pellets, for example, in the form of pellets, oval pellets or go, the long diameter thereof is in the range of 1 to 5mm, for example, ：1.5～5.0mm、2.2～5.0mm、2.4～5.0mm、2.6～5.0 mm、2.8～5.0mm、3.0～5.0mm、3.2～5.0mm、3.4～5.0mm、3.6～5.0mm、3.8～5.0 mm、4.0～5.0mm、2.0～4.5mm、2.0～4.4mm、2.0～4.2mm、2.0～4.0mm、2.0～3.8 mm、2.0～3.6mm、2.0～3.4mm、2.0～3.2mm、2.0～3.0mm;, and the short diameter thereof is in the range of 1 to 5mm, for example, ：1.5～5.0mm、1.8～4.6mm、2.4～4.6mm、2.6～4.6mm、2.8～4.6 mm、3.0～4.6mm、3.2～4.6mm、3.4～4.6mm、3.6～4.6mm、3.8～4.6mm、4.0～4.6 mm、1.6～4.5mm、1.6～4.4mm、1.6～4.2mm、1.6～4.0mm、1.6～3.8mm、1.6～3.6 mm、1.6～3.4mm、1.6～3.2mm、1.6～3.0mm,, and when the pellets are in the form of pellets, the long diameter and the short diameter are equal.

According to some embodiments of the invention, the weight percentage of the first EVOH resin pellets to the second EVOH resin pellets is 5:95 to 75:25, for example: 5: 95. 15: 85. 25: 75. 35: 65. 45: 55. 55: 45. 65:35 or 75:25.

According to some embodiments of the present invention, the EVOH resin pellet composition may in some cases comprise a boron compound and/or boric acid and/or cinnamic acid and/or an alkali metal and/or a conjugated polyene and/or a slip agent and/or an alkaline earth metal. The above substances can impart better properties to the EVOH resin pellet composition.

According to some embodiments of the present invention, the EVOH resin pellet composition may comprise a boron compound having a boron content of 5 to 550ppm. In some cases, the boron content of the EVOH resin pellet composition may be from 10 to 450ppm, from 10 to about 400 ppm, from 10 to about 350ppm, from 10 to about 300ppm, from 10 to about 275ppm, from 10 to about 250ppm, from 10 to about 225ppm, from 10 to about 200ppm, from 10 to about 175ppm, from about 20 to 450ppm, from about 20 to about 400 ppm, from about 20 to about 350ppm, from about 20 to about 300ppm, from about 20 to about 275ppm, from about, About 20 to about 250ppm, about 20 to about 225ppm, about 20 to about 200ppm, about 20 to about 175ppm, about 60 to about 450ppm, about 60 to about 400ppm, about 60 to about 350ppm, about 60 to about 300ppm, about 60 to about 275ppm, about 60 to about 250ppm, about 60 to about 225ppm, about 60 to about 200ppm, about 60 to about 175ppm, about 100 to about 450ppm, about 100 to about 400ppm, about 100 to about 350ppm, about 100 to about 300ppm, about 100 to about 275ppm, about 100 to about 250ppm, about 100 to about 225ppm, about 100 to about 200ppm, about 100 to about 175ppm, about 140 to 450ppm, about 140 to about 400ppm, about 140 to about 350ppm, about 140 to about 300ppm, about 140 to about 275ppm, about 140 to about 250ppm, about 140 to about 225ppm, about 140 to about 200ppm, about 180 to about 450ppm, about 180 to about 400ppm, about 180 to about 350ppm, About 180 to about 300ppm, about 180 to about 275ppm, about 180 to about 250ppm, about 180 to about 225ppm, about 220 to 450ppm, about 220 to about 400ppm, about 220 to about 350ppm, about 220 to about 300ppm, about 220 to about 275ppm. When the boron content of the EVOH resin pellet composition is within a certain range, it is possible to increase the viscosity of the EVOH resin pellet composition and reduce the chance of the EVOH resin pellet composition adhering to the screw, or to remove the EVOH on the screw, thereby giving the material a self-cleaning function and further improving the uniformity of film thickness. According to a preferred embodiment of the present invention, the EVOH resin pellet composition may further comprise cinnamic acid, alkali metal, conjugated polyene, alkaline earth metal, salt thereof, and/or mixture thereof in addition to the boron compound; the above materials are common materials commonly found in EVOH resin pellet compositions, and give them better properties. The content of the compound having a conjugated polyene structure is 1 to 30000ppm per unit weight of the EVOH resin pellet composition, whereby coloration after heating can be further suppressed, and the heat stability is further excellent. When the content of the alkali metal compound or alkaline earth metal compound is 10 to 550ppm in terms of metal per unit weight of the EVOH resin composition, the long-term run formability is further improved; The content may be, for example, according to different situations: between 10 and 550ppm, between about 10 and 500ppm, between about 10 and 450ppm, between about 10 and 400ppm, between about 10 and 350ppm, between about 10 and 300ppm, between about 10 and 250ppm, between about 10 and 200ppm, between about 10 and 150ppm, between about 10 and 100ppm, between about 10 and 50ppm, between about 50 and 550ppm, between about 50 and 500ppm, between about 50 and 450ppm, About 50-400ppm, about 50-350ppm, about 50-300ppm, about 50-250ppm, about 50-200ppm, about 50-150ppm, about 50-100ppm, about 100-550ppm, about 100-500ppm, about 100-450ppm, about 100-400ppm, about 100-350ppm, about 100-300 ppm, about 100-250ppm, about 100-200ppm, About 100-150ppm, about 200-550ppm, about 200-500ppm, about 200-450ppm, about 200-400ppm, about 200-350ppm, about 200-300ppm, about 200-250ppm, about 300-550 ppm, about 300-500ppm, about 300-450ppm, about 300-400ppm, about 300-350ppm, about 400-550ppm, about 400-500ppm, Between about 400-450ppm or between about 500-550ppm.

According to some embodiments of the invention, the boron compound may include boric acid or a metal salt thereof. Examples of metal salts include, but are not limited to, calcium borate, cobalt borate, zinc borate (e.g., zinc tetraborate, zinc metaborate), aluminum potassium borate, ammonium borate (e.g., ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate), cadmium borate (e.g., cadmium orthoborate, cadmium tetraborate), potassium borate (e.g., potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate), silver borate (e.g., silver metaborate, silver tetraborate), copper borate (e.g., copper (II) borate, copper metaborate, copper tetraborate), sodium borate (e.g., sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate), lead borate (e.g., lead metaborate, lead hexaborate), nickel borate (e.g., nickel orthoborate, nickel tetraborate), barium borate (e.g., barium orthoborate, barium tetraborate), bismuth borate, magnesium borate (e.g., magnesium orthoborate, magnesium tetraborate, magnesium metaborate), magnesium metaborate, magnesium tetraborate, manganese tetraborate (e.g., I), lithium tetraborate, or a combination thereof). Borate minerals such as borax, kainite, slate, granite, asconite/kanite (suanite) and paigeite (szaibelyite) may be included. Among them, borax, boric acid and sodium borate (e.g., sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate and sodium octaborate) are preferably used.

According to some embodiments of the invention, the first EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0020 to 25, for example: between about 0.0100 and 25, between about 0.1000 and 25, between about 1 and 23.3000, between about 1 and 20, between about 1 and 15, between about 5 and 15, or between about 7 and 10. In another aspect, the second EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0070 to 111, such as: between about 0.0100-111, 0.0200-100, between about 0.2000-65, between about 2-50, between about 2-40, between about 10-40, or between about 20-40.

As used herein, the definition of the so-called "kurtosis (Sku) surface parameter" refers to ISO 25178:2012; it is understood that the height distribution of the inner contour surface within a sampling range is a parameter for determining the sharpness of the surface shape.

According to some embodiments of the invention, the first EVOH resin particles have a surface parameter of 0.0005 to 29 um of the surface maximum peak height (Sp), for example: about 0.0005 to 28um, about 0.0010 to 25um, about 0.0100 to 25um, about 0.1000 to 25um, about 1 to 20 um, about 1 to 15um, about 5 to 15um, or about 7 to 10um. On the other hand, the second EVOH resin particles have a surface parameter of a surface maximum peak height (Sp) of 0.0020 to 63 μm, for example: about 0.0020 to 60um, about 0.0200 to 60um, about 0.2000 to 60um, about 2 to 60um, about 10 to 60um, about 20 to 50um, about 25 to 40um, about 30 to 40um, or about 30 to 36um.

As used herein, the definition of the "maximum peak height (Sp) surface parameter" refers to ISO25178:2012, which is understood as the maximum height value relative to a reference plane over a sampling range.

According to some embodiments of the invention, the first EVOH resin particles have a protruding peak height (Spk) surface parameter of 0.001 to 2um, for example: between about 0.001 and 2um, between about 0.005 and 2um, between about 0.010 and 2um, between about 0.050 and 2um, between about 0.100 and 1um, or between about 0.500 and 1um. On the other hand, the second EVOH resin particles have a protruding peak height (Spk) surface parameter of 0.003 to 22 μm, for example: about 0.003 to 20um, about 0.030 to 20um, about 0.300 to 20um, about 1 to 20um, about 5 to 15um, or about 5 to 10um.

As used herein, the definition of the so-called "protruding peak height (Spk) surface parameter" refers to ISO 25178:2012; specifically, it refers to the average height of the protruding crest.

According to some embodiments of the invention, the first EVOH resin particles have a pole height (Sxp) surface parameter of 0.001 to 12 um, for example: between about 0.001 and 11um, between about 0.005 and 10um, between about 0.010 and 2um, between about 0.050 and 2um, between about 0.100 and 1um, or between about 0.500 and 1um. In another aspect, the second EVOH resin particles have a pole height (Sxp surface parameter of from about 0.003 to 48um, for example, from about 0.030 to 30um, from about 0.300 to 20um, from about 1 to 20um, from about 5 to 15um, or from about 5 to 10 um) of from 0.002 to 48 um.

As used herein, the definition of the so-called "pole height (Sxp) surface parameter" refers to ISO 25178:2012; specifically, it means that the height difference between the surface average surface and the surface peak portion after removing the peak particularly high in the surface, and the height difference between the load area ratio of 2.5% and 50% is shown by default.

According to some embodiments of the invention, the first EVOH resin particles have a linear arithmetic mean height (Ra) surface parameter of 0.001 to 0.990um, for example: about 0.001 to about 0.990um, about 0.001 to about 0.700um, about 0.001 to about 0.500um, about 0.001 to about 0.300um, about 0.001 to about 0.100um, about 0.050 to about 0.990um, about 0.050 to about 0.700um, about 0.050 to about 0.500um, about 0.050 to about 0.300um, or about 0.050 to about 0.100um. On the other hand, the second EVOH resin particles have a linear arithmetic average height (Ra) surface parameters of 0.001 to 0.990um, such as: about 0.001 to about 0.990um, about 0.001 to about 0.700um, about 0.001 to about 0.500um, about 0.010 to about 0.300um, about 0.010 to about 0.100um, about 0.050 to about 0.990um, about 0.050 to about 0.700um, about 0.050 to about 0.500um, about 0.050 to about 0.300um, or about 0.050 to about 0.100um.

As used herein, the term "line arithmetic mean height (Ra) surface parameter" is a parameter defining surface roughness, which definition can be understood with reference to JIS B0601, in particular, as the mean absolute value of a profile curve over a reference length.

According to some embodiments of the invention, the first EVOH resin particles have a line maximum height (Rz) surface parameter of 0.0010 to 9.9000um, for example: between about 0.0010 and 9um, between about 0.0010 and 7um, between about 0.0010 and 5um, between about 0.0100 and 3um, between about 0.0500 and 5um, between about 0.0500 and 3um, between about 0.0500 and 1um, or between about 0.0500 and 0.0800um. On the other hand, the second EVOH resin particles have a line maximum height (Rz) surface parameter of 0.0010 to 9.9000um, for example: between about 0.0800 and 9um, between about 0.1000 and 9um, between about 0.1500 and 7um, between about 0.5000 and 5um, between about 0.5000 and 2.5000um, or between about 1 and 2.5000um. As used herein, the term "line maximum height (Rz) surface parameter" is a parameter defining the surface roughness, which definition can be understood with reference to JIS B0601, specifically, which is the distance of a contour curve from the highest peak and lowest trough on a reference length.

In another aspect, the present invention provides an ethylene-vinyl alcohol copolymer film formed from the EVOH resin pellet composition described above. Specifically, the ethylene-vinyl alcohol copolymer film is a single layer film.

According to some embodiments of the invention, the polymer layer is selected from the group consisting of a low density polyethylene layer, a polyethylene grafted maleic anhydride (polyethylene GRAFTED MALEIC ANHYDRIDE) layer, a polypropylene layer, and a nylon layer, and the adhesive layer is a tie layer, such as ARKEMA OREVAC 18729 from ARKEMA. Specifically, the laminated structure of the multi-layer structure is sequentially a polymer layer, an adhesive layer, an ethylene-vinyl alcohol copolymer film, an adhesive layer and a polymer layer. According to some embodiments of the invention, the thickness of the polymer layer is 100 to 500um, preferably 200 to 400um, more preferably 300um; the thickness of the adhesive layer is 10-40 um, preferably 20-30 um, more preferably 25um; the ethylene-vinyl alcohol copolymer film has a thickness of 20 to 80. Mu.m, preferably 40 to 60. Mu.m, more preferably 50. Mu.m.

Without being bound by any theory, it is believed that since the surface peak bulk volume (Vmp) is the dominant factor affecting tip heat conduction, it is related to melting conditions during material processing that can further affect the heat conduction uniformity during processing of the first EVOH resin pellets as well as the second EVOH resin pellets. Therefore, when the Vmp value of the first EVOH resin pellet and the second EVOH resin pellet in the EVOH resin pellet composition is within a specific range, and the surface roughness of the EVOH peak with high melting point is large, the peak part is preferentially melted during processing, so that the heat conduction of the plastic pellet is more uniform, and the melting area temperature is forward; when the EVOH peak surface roughness with low melting point is smaller, the local overheating of the peak part during processing can be reduced; therefore, the solid volume (Vmp) of the peak parts on the surfaces of the two EVOH resin particles is controlled to regulate the heat conduction state after melt mixing, so that the two EVOH resin particles can be uniformly melted, and further, an EVOH film with good processability and mechanical properties is obtained later.

Examples

The following non-limiting examples of aspects of the invention are provided primarily to illustrate aspects of the invention and the benefits achieved thereby. The EVOH formulations of each of the examples and comparative examples were prepared from at least two components. More specifically, the two components of the EVOH resin pellet compositions of examples and comparative examples are two types of EVOH resin pellets.

Preparation of EVOH resin pellet composition

The following provides a non-limiting method of preparing EVOH resin pellet compositions. According to a method similar to the method disclosed below, 5 non-limiting example EVOH resin pellet compositions (example EVOH 1-5) and 6 comparative example EVOH resin pellet compositions (comparative example EVOH 1-6) were prepared. However, the specific methods of preparing example EVOH 1-5 and comparative example EVOH 1-6 will generally vary in one or more respects from the methods disclosed below.

First EVOH resin pellet of example 1

500Kg of vinyl acetate, 100kg of methanol, 0.0585kg of acetyl peroxide and 0.015kg of citric acid were charged into a polymerization reactor equipped with a cooling coil, the inside of the polymerization reactor was replaced with nitrogen gas, and then replaced with ethylene and then pressure-fed until the ethylene pressure became 45kg/cm ². The polymerization was started by heating to 67℃under stirring in an ethylene pressurized environment. After 6 hours from the start of polymerization, 0.0525kg of sorbic acid conjugated polyene as a polymerization inhibitor was added at the point when the polymerization rate reached 60%. Thus, an ethylene-vinyl acetate copolymer having an ethylene structural unit content of 44mole% was obtained. Then, the reaction solution containing the ethylene-vinyl acetate copolymer was supplied to a distillation column, and methanol vapor was introduced from the lower part of the column to remove unreacted vinyl acetate, thereby obtaining a methanol solution of the ethylene-vinyl acetate copolymer.

In this example, an ethylene-VINYL ACETATE copolymer (hereinafter referred to as "EVAC" polymer) was formed by polymerizing ethylene monomer and vinyl acetate monomer, and saponification was performed at a saponification degree of 99.5% to form EVOH. Subsequently, EVOH was dissolved in an aqueous alcohol solution having a ratio of methanol to water of 70:30. The EVOH/methanol/water solution was left at 60℃for 1 hour to promote dissolution of the EVOH in the EVOH/methanol/water solution. The solids content of the EVOH/methanol/water solution was 41wt%.

Subsequently, the solution of methanol, water and EVOH was pelletized by strand cutting (Strip cut). Specifically, the solution of methanol, water and EVOH was pumped into a feed pipe at a flow rate of 120L/min by using a pump, and then fed into a circular opening die having a diameter of 0.5mm, the EVOH solution was extruded into a water/methanol mixed solution (water/methanol mass ratio=9/1) at 5 ℃ to precipitate a strand-like shape of a port, and the strand was cut by a rotary blade at a rotation speed of 500rpm to obtain pellets of EVOH. Subsequently, the EVOH pellets were centrifuged to separate EVOH pellets, and the separated EVOH pellets were washed with water; then carrying out the centrifugal dehydration step for the second time, immersing the EVOH particles in a boric acid/sodium acetate solution, then carrying out a drying step and adding calcium stearate to obtain an EVOH resin particle final product, wherein the drying is carried out in three stages, and a belt dryer is used for the first stage of drying, and the drying is carried out at 80 ℃ for 2 hours; drying for 20 hours at 100 ℃ by using a belt dryer in the second stage; the third stage of drying uses a flow dryer, drying for 20 hours at 120 ℃, and finally transporting the granules, the transport being carried out in the following cases: the conveying mode is air conveying, the diameter of a pipeline is 6 inches, the number of the bent heads is 4, the length of the pipeline is 30 meters, and the conveying speed is 40m/min. The first EVOH resin pellets of this example were cylindrical in shape, with a height of 5mm and a minor diameter of 1mm.

In the centrifugation and washing steps, the rotation speed of the first dehydrator is 5000rpm; the water/wet grain ratio is 10 during conveying; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 3000rpm; the weight ratio of water to wet particles is 5 during water washing; the water flow speed is 2m/min during water washing; the second dehydrator speed was 2000rpm.

Second EVOH resin pellet of example 1

The second EVOH resin pellets of example 1 were prepared herein using a process similar to that described above. The difference is that an ethylene-vinyl acetate copolymer (hereinafter referred to as "EVAC") having an ethylene content of 32mole% was saponified at a saponification degree of 99.5% to prepare an EVOH polymer. And the open die diameter of the strip cut was 2mm, and the rotational speed of the rotary knife was 2000rpm.

In the centrifugation and washing steps adopted for the second EVOH resin pellets of the present example, the first dehydrator rotation speed was 3000rpm; the water/wet grain ratio during conveying is 3; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 2000rpm; the weight ratio of water to wet particles is 3 during water washing; the water flow speed is 2.5m/min during water washing; the second dehydrator speed was 3000rpm. The final product of the second EVOH resin pellet of this example was cylindrical, with a height of 2mm and a minor diameter of 3mm.

For the subsequent further process, the above-mentioned first EVOH resin pellets and second EVOH resin pellets were further mixed in a proportion of 25 and 75wt% respectively as the EVOH resin pellet composition of example 1, mixed by a conical screw mixer (model: CM-2, available from Xshihui mechanical Co., ltd.) at 10rpm for 5 minutes.

First and second EVOH resin pellets of example 2

The first and second aqueous EVOH solutions for example 2 were prepared using a similar procedure (preparation process) to the EVOH resin pellets of example 1. However, when the first EVOH aqueous methanol solution of example 2 was prepared, the ethylene content was 48mole%; and the pelletization step pelletizes the solution of methanol, water and EVOH by underwater pelletization (underwater pelletization). Specifically, the foregoing solution of methanol, water and EVOH was pumped into a feed pipe at a flow rate of 120L/min using a pump, and then fed into an input pipe having a diameter of 1mm, and cut at 1500rpm using a rotary knife to obtain pellets of EVOH. While the EVOH pellets were cooled by circulating condensate at 5 ℃. Subsequently, the EVOH pellets were centrifuged to separate EVOH pellets, and the separated EVOH pellets were washed with water; the above-mentioned centrifugal dehydration step is performed again, followed by immersing the EVOH pellets in a boric acid/sodium acetate solution, followed by a drying step and adding calcium stearate to obtain an EVOH resin pellet end product. The first EVOH resin pellet of this example was oval in shape, with a major diameter of 3mm and a minor diameter of 2mm.

In the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 3000rpm; the water/wet grain ratio is 10 during conveying; the type of centrifugal pump (pump) for transportation is semi-open; the rotational speed of the delivery pump (pump) is 4000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 2m/min during water washing; the rotation speed of the second dehydrator is 1000rpm; finally, the product of the first EVOH resin pellet was in the form of an oval sphere having a major diameter of 3mm and a minor diameter of 2mm.

On the other hand, when the second EVOH aqueous methanol solution of example 2 was prepared, its ethylene content was 27mole%; and a similar process to the first EVOH resin pellet of example 2 was used; and the diameter of the input tube is 2mm: in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 2000rpm; the water/wet grain ratio is 5 during conveying; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the transfer pump (pump) is 1000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 5m/min during water washing; the rotation speed of the second dehydrator is 3000rpm; finally, the product of the second EVOH resin pellet was in the form of a sphere having a minor diameter of 3mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 10 and 90wt% respectively, to form an EVOH resin pellet composition of example 2.

First and second EVOH resin pellets of example 3

The first aqueous EVOH methanol solution for example 3 was prepared using a similar process to the EVOH resin pellets of example 2. However, the ethylene content of the first EVOH aqueous methanol solution of example 3 was 38mole% when prepared; and using a process similar to that of the first EVOH resin pellet of example 2, the diameter of the input tube was 0.5mm and the rotating knife rotation speed was 3000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 2500rpm; the water/wet grain ratio is 8 during conveying; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the delivery pump (pump) is 5000rpm; the weight ratio of water to wet particles is 8 during water washing; the water flow speed is 2.5m/min during water washing; the rotation speed of the second dehydrator is 3000rpm; finally, the product of the first EVOH resin pellet was in the form of a sphere having a minor diameter of 1mm.

On the other hand, when the second EVOH aqueous methanol solution of example 3 was prepared by using a similar process to the EVOH resin pellet of example 1, the ethylene content was 29mole%; the diameter of the open die of the strip cutter is 4mm, and the rotating speed of the rotary cutter is 3000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 1000rpm; the water/wet grain ratio is 5 during conveying; the type of centrifugal pump (pump) for transportation is semi-open; the rotational speed of the delivery pump (pump) is 5000rpm; the weight ratio of water to wet particles is 5 during water washing; the water flow speed is 5m/min during water washing; the rotation speed of the second dehydrator is 4000rpm; finally, the product of the second EVOH resin pellet was cylindrical, with a height of 1mm and a minor diameter of 5mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 50 and 50wt%, respectively, to form an EVOH resin pellet composition of example 3.

First and second EVOH resin pellets of example 4

The first EVOH resin pellets used in example 4 were prepared using a similar process to the EVOH resin pellets of example 2. However, when the first EVOH aqueous methanol solution of example 4 was prepared, the ethylene content was 48 mol%; the diameter of the input pipe is 0.5mm, and the rotating speed of the rotary knife is 500rpm; in the centrifugal and washing steps adopted, the rotating speed of the first dehydrator is 2500rpm; the water/wet grain ratio is 6 during conveying; the type of centrifugal pump (pump) for transportation is semi-open; the rotational speed of the delivery pump (pump) is 5000rpm; the weight ratio of water to wet particles is 7 during water washing; the water flow speed is 2m/min during water washing; the rotation speed of the second dehydrator is 4000rpm; finally, the product of the first EVOH resin pellet was in the form of an oval sphere having a major diameter of 5mm and a minor diameter of 1mm.

On the other hand, when the second EVOH aqueous methanol solution of example 4 was prepared using a similar process to the EVOH resin pellet of example 1, its ethylene content was 32 mole%; the diameter of the open die of the strip cutter is 2mm, and the rotating speed of the rotary cutter is 1500rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 3000rpm; the water/wet grain ratio during conveying is 9; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the delivery pump (pump) is 4000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 5m/min during water washing; the rotation speed of the second dehydrator is 4000rpm; finally, the product of the second EVOH resin pellet was cylindrical, with a height of 3mm and a minor diameter of 3mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 15 to 85wt% respectively, to obtain an EVOH resin pellet composition of example 4.

First and second EVOH resin pellets of example 5

The first and second EVOH resin pellets used in example 5 were prepared using a similar process to the EVOH resin pellets of example 2. However, when the first EVOH aqueous methanol solution of example 5 was prepared, its ethylene content was 38 mole%; the diameter of the input pipe is 1mm, and the rotating speed of the rotary knife is 1000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 4000rpm; the water/wet grain ratio during conveying is 7; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 3000rpm; the weight ratio of water to wet particles is 8 during water washing; the water flow speed is 7m/min during water washing; the rotation speed of the second dehydrator is 2000 rpm; finally, the product of the first EVOH resin pellet was in the form of an oval sphere having a major diameter of 4mm and a minor diameter of 2mm.

On the other hand, when the second EVOH aqueous methanol solution of example 5 was prepared, its ethylene content was 24 mol%; the diameter of the input pipe is 0.5mm, and the rotating speed of the rotary knife is 1000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 5000rpm; the water/wet grain ratio during conveying is 9; the type of centrifugal pump (pump) for delivery is semi-open; the rotational speed of the transfer pump (pump) is 3000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 6m/min during water washing; the rotation speed of the second dehydrator is 1000rpm; finally, the product of the second EVOH resin pellet was in the form of an oval sphere having a major diameter of 4mm and a minor diameter of 1mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 35 wt% and 65wt%, respectively, to form an EVOH resin pellet composition of example 5.

First and second EVOH resin pellets of comparative example 1

The first EVOH resin pellet for comparative example 1 was prepared using a similar process to the EVOH resin pellet of example 2. However, when the first EVOH aqueous methanol solution of comparative example 1 was prepared, the ethylene content thereof was 44 mol%; the diameter of the input pipe is 2.5mm, and the rotating speed of the rotary knife is 1200rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 2000rpm; the water/wet grain ratio is 10 during conveying; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 1000rpm; the weight ratio of water to wet particles is 15 during water washing; the water flow speed is 2m/min during water washing; the rotation speed of the second dehydrator is 1000rpm; finally, the product of the first EVOH resin pellet was in the form of a sphere having a minor diameter of 3.5mm.

On the other hand, when the second EVOH aqueous methanol solution of comparative example 1 was prepared by using a similar process to the EVOH resin pellet of example 1, the ethylene content was 29 mol%; the diameter of the open die of the strip cutter is 3.5mm, and the rotating speed of the rotary cutter is 500rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 1000rpm; the water/wet grain ratio during conveying is 15; the type of centrifugal pump (pump) for transportation is open type; the rotational speed of the transfer pump (pump) is 2000rpm; the weight ratio of water to wet particles is 20 during water washing; the water flow speed is 1m/min during water washing; the rotation speed of the second dehydrator is 1000rpm; finally, the product of the second EVOH resin pellet was cylindrical with a height of 5mm and a minor diameter of 4.5mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 5 to 95wt% respectively, to obtain an EVOH resin pellet composition of comparative example 1.

First and second EVOH resin pellets of comparative example 2

The first EVOH resin pellet for comparative example 2 was prepared using a similar process to the EVOH resin pellet of example 2. However, when the first EVOH aqueous methanol solution of comparative example 2 was prepared, the ethylene content thereof was 35 mol%; the diameter of the input pipe is 1mm, and the rotating speed of the rotary knife is 1500rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 3000rpm; the water/wet grain ratio during conveying is 20; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 1000rpm; the weight ratio of water to wet particles is 15 during water washing; the water flow speed is 1.5m/min during water washing; the rotation speed of the second dehydrator is 2000 rpm; finally, the product of the first EVOH resin pellet was in the form of an oval sphere having a major diameter of 3mm and a minor diameter of 2mm.

On the other hand, the second EVOH resin pellet of comparative example 2 was produced using a similar process to that of the EVOH resin pellet of example 1, however, when the second EVOH aqueous methanol solution of comparative example 2 was produced, the ethylene content was 24 mol%; the diameter of the open die of the strip cutter is 1mm, and the rotating speed of the rotary cutter is 1000rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 8000rpm; the water/wet grain ratio is 1 during conveying; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the delivery pump (pump) is 8000rpm; the weight ratio of water to wet particles is 1 during water washing; the water flow speed is 8m/min during water washing; the rotation speed of the second dehydrator is 5000rpm; finally, the product of the second EVOH resin pellet was cylindrical, with a height of 4mm and a minor diameter of 2mm. Further, the first EVOH resin pellet and the second EVOH resin pellet were further mixed at a ratio of 75wt% and 25wt%, respectively, to obtain an EVOH resin pellet composition of comparative example 2.

First and second EVOH resin pellets of comparative example 3

First and second EVOH resin pellets for comparative example 3 were prepared using a similar process to the EVOH resin pellets of example 1. However, when the first EVOH aqueous methanol solution of comparative example 3 was prepared, the ethylene content thereof was 48 mol%; the diameter of the open die of the strip cutter is 3mm, and the rotating speed of the rotary cutter is 1700rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 7000rpm; the water/wet grain ratio during conveying is 3; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the transfer pump (pump) is 7000rpm; the weight ratio of water to wet particles is 1 during water washing; the water flow speed is 7m/min during water washing; the rotation speed of the dehydrator for the second time is 6000rpm; finally, the product of the first EVOH resin pellet was cylindrical with a height of 2.5mm and a minor diameter of 4mm. On the other hand, when the second aqueous methanol solution of comparative example 3 was prepared, the ethylene content thereof was 32 mol%; the diameter of the open die of the strip cutter is 2mm, and the rotating speed of the rotary cutter is 1200rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 6000rpm; the water/wet grain ratio is 1 during conveying; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the delivery pump (pump) is 6000rpm; the weight ratio of water to wet particles is 3 during water washing; the water flow speed is 6m/min during water washing; the rotation speed of the second dehydrator is 5000rpm; finally, the product of the second EVOH resin pellet was cylindrical, with a height of 3.5mm and a minor diameter of 3mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 15 to 85wt% respectively, to obtain an EVOH resin pellet composition of comparative example 3.

First and second EVOH resin pellets of comparative example 4

The first and second EVOH resin pellets for comparative example 4 were prepared using a similar process to the EVOH resin pellets of example 2. However, when the first EVOH aqueous methanol solution of comparative example 4 was prepared, the ethylene content thereof was 38 mol%; the diameter of the input pipe is 0.5mm, and the rotating speed of the rotary knife is 3000rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 3000rpm; the water/wet grain ratio is 8 during conveying; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the delivery pump (pump) is 4000rpm; the weight ratio of water to wet particles is 8 during water washing; the water flow speed is 2.5m/min during water washing; the rotation speed of the second dehydrator is 3000rpm; finally, the product of the first EVOH resin pellet was in the form of a sphere having a minor diameter of 1mm. On the other hand, when the second EVOH aqueous methanol solution of comparative example 4 was prepared, the ethylene content thereof was 27 mol%; the diameter of the input pipe is 3mm, and the rotating speed of the rotary knife is 1000rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 8000rpm; the water/wet grain ratio is 1 during conveying; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the delivery pump (pump) is 8000rpm; the weight ratio of water to wet particles is 3 during water washing; the water flow speed is 6m/min during water washing; the rotation speed of the dehydrator for the second time is 6000rpm; finally, the product of the second EVOH resin pellet was in the form of a sphere having a minor diameter of 4mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 10 and 90wt% respectively, to give an EVOH resin pellet composition of comparative example 4.

First and second EVOH resin pellets of comparative example 5

The first and second EVOH resin pellets for comparative example 5 were prepared using a similar process to the EVOH resin pellets of example 2. However, when the first EVOH aqueous methanol solution of comparative example 5 was prepared, the ethylene content thereof was 44 mol%; the diameter of the input pipe is 2.5mm, and the rotating speed of the rotary knife is 1000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 1000rpm; the water/wet particle ratio during conveying is 10; the type of centrifugal pump (pump) for delivery is open; the rotational speed of the transfer pump (pump) is 3000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 1m/min during water washing; the rotation speed of the second dehydrator is 1000rpm; finally, the product of the first EVOH resin pellet was in the form of an oval sphere having a major diameter of 4mm and a minor diameter of 3.5mm. On the other hand, when the second EVOH aqueous methanol solution of comparative example 5 was prepared, the ethylene content thereof was 29 mol%; the diameter of the input pipe is 0.5mm, and the rotating speed of the rotary knife is 1700rpm; in the centrifugation and washing steps adopted, the rotating speed of the first dehydrator is 3000rpm; the water/wet grain ratio is 5 during conveying; the type of centrifugal pump (pump) for conveying is closed; the rotational speed of the transfer pump (pump) is 2000rpm; the weight ratio of water to wet particles is 10 during water washing; the water flow speed is 5m/min during water washing; the rotation speed of the second dehydrator is 3000rpm; finally, the product of the second EVOH resin pellet was in the form of an oval sphere having a major diameter of 2.5mm and a minor diameter of 1mm. Further, the first EVOH resin pellets and the second EVOH resin pellets were further mixed at a ratio of 20 to 80wt% respectively, to obtain an EVOH resin pellet composition of comparative example 5.

First and second EVOH resin pellets of comparative example 6

First and second EVOH resin pellets for comparative example 6 were prepared using a similar process to the EVOH resin pellets of example 2. However, when the first EVOH aqueous methanol solution of comparative example 6 was prepared, the ethylene content thereof was 38 mol%; the diameter of the input pipe is 1.5mm, and the rotating speed of the rotary knife is 1700rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 7000rpm; the water/wet particle ratio during conveying is 2; the type of centrifugal pump (pump) for transportation is closed; the rotational speed of the delivery pump (pump) is 8000rpm; the weight ratio of water to wet particles is 3 during water washing; the water flow speed is 10m/min during water washing; the rotation speed of the dehydrator for the second time is 6000rpm; finally, the product of the first EVOH resin pellet was in the form of a sphere having a minor diameter of 2.5mm. On the other hand, when the second EVOH aqueous methanol solution of comparative example 6 was prepared, the ethylene content thereof was 32 mol%; the diameter of the input pipe is 0.5mm, and the rotating speed of the rotary knife is 1000rpm; in the centrifugation and washing steps adopted, the rotation speed of the first dehydrator is 1000rpm; the water/wet grain ratio during conveying is 3; the type of centrifugal pump (pump) for transportation is semi-open; the rotational speed of the transfer pump (pump) is 3000rpm; the weight ratio of water to wet particles is 5 during water washing; the water flow speed is 3m/min during water washing; the rotation speed of the second dehydrator is 4000rpm; finally, the product of the second EVOH resin pellet was in the form of an oval sphere having a major diameter of 4mm and a minor diameter of 1mm. Further, the first EVOH resin pellet and the second EVOH resin pellet were further mixed at a ratio of 35 wt% and 65wt%, respectively, to obtain an EVOH resin pellet composition of comparative example 6.

Parameters of EVOH resin pellets

The parameters of the EVOH resin pellets of the present invention and the evaluation/analysis methods thereof are provided below.

Particle surface roughness

To evaluate/analyze the surface roughness of the EVOH resin pellets of the examples, the pellets of EVOH resin were laid flat over a plate for measurement of the pellet surface roughness; the data for which the inclination is greater than 0.5 is excluded from the measurement to ensure that the scan plane is relatively horizontal (inclination = maximum face height Sz/edge length of the analysis range 129 μm). The laser microscope was used for LEXT OLS5000-SAF manufactured by Olympus, and the image was made at an air temperature of 24.+ -. 3 ℃ and a relative humidity of 63.+ -. 3%. The filter is set to no filtering. The light source is a 405 nm-wavelength light source. The objective lens is 100x magnification (MPLAPON-100 xLEXT). The optical zoom is set to 1.0x. The image area was set to 129 μm m x μm (the center line of the image area was taken when Rz was measured). The resolution is set to 1024 pixels by 1024 pixels. The values of 100 particles were measured and averaged. Wherein Vmp, sku, sp, spk and Sxp are measured using the method of ISO 25178:2012; ra and Rz are measured by JIS B0601 (2001).

Ethylene content analysis

In order to evaluate/analyze the ethylene content of the EVOH resin pellets of the examples, the present invention employs a Raman spectrometer manufactured by UniDRON, and randomly measures the ethylene content of 5 sites in each EVOH resin pellet with a laser light source having a wavelength of 473nm, and takes the average value thereof as the ethylene content value of the EVOH resin pellet sample.

Melting point analysis

The melting point temperature of EVOH resin pellets was measured by DSC Q200 apparatus (manufactured by Xi Luo technologies Co., ltd., TZERO TECHNOLOGIES, INC.; lid (Tzero lid) for TA instrument T170607, and chassis (Tzero pan) for TA instrument T170620) according to ISO 11357-3-2011.

Practically speaking, without being limited to a particular theory, when there are a large number of EVOH resin pellets, 100 EVOH resin pellets may be taken first and another ethylene content thereof may be obtained by the above-mentioned ethylene content analysis method. Subsequently, for those having an ethylene content of 35 to 48 mol%, they are first classified in advance as low-melting EVOH resin pellets having a melting point of about 135 to 179 ℃; whereas, for those having an ethylene content of 24 to 34 mol%, they are classified in advance as high-melting EVOH resin pellets having a melting point of about 180 to 198 ℃. Further, 10 EVOH resin pellets were randomly taken out of each of the low-melting EVOH resin pellets and the high-melting EVOH resin pellets, the surface roughness was obtained by the above-mentioned surface parameter measurement method, and the melting points of the EVOH resin pellets were determined by the above-mentioned melting point measurement method.

Preparation and analysis of EVOH monolayer films

The EVOH resin pellet compositions of examples 1 to 5 and comparative examples 1 to 6 were formed into films according to the following methods. The EVOH resin pellet compositions of examples 1 to 5 and comparative examples 1 to 6 were fed into a single screw extruder (model ME25/5800V4, brand OCS) to be extruded to prepare a monolayer film. The thickness of the films formed from the EVOH resin pellet compositions of examples 1 to 5 and comparative examples 1 to 6 was 20. Mu.m. The temperature of the extruder was set to 220 ℃; and the rotational frequency of the screw was set to 7rpm (rotations/minutes).

Processability analysis of EVOH film: determination and evaluation of Gel particles (Gel)

Here, gel particle measurement analysis was performed on the EVOH film using a charge coupled device (charged coupled device, CCD) sensor and FSA-100 designed with FSA-100V.8 software. The evaluation mode is as follows: if the gel particle size is <100 μm, the amount is <450, namely, the optimal value is represented by 'O'; the number of the catalyst is 450-1000, namely the catalyst is expressed as delta; while those whose number is >1000 are not good represented by "X". If the gel particle size is 100-200 μm, the quantity is less than 50, namely, the optimal quantity is represented by 'O'; the number of the components is 50-100, namely, the components are represented by delta; while those whose number is >100 are not good represented by "X". If the gel particle size is >200 μm, the amount is less than 10, namely, the "O" is the best; the number of which is 10-20 is represented by delta; and the number is >20, the "X" is not good.

Mechanical property analysis of EVOH films: measurement and evaluation of film elongation

The single-screw extruder is used for forming a single-layer film with the thickness of 180um, and the single-layer film is cut into a size (TRANSVERSE DIRECTION, TD or width direction) of 90mm of TD 30mm, wherein MD refers to Machine Direction, namely the mechanical direction, the longitudinal direction and the length direction; then, after being placed in an environment at 130℃for 30 minutes, the tensile force was measured in the MD and TD directions at a tensile force rate of 1000mm/min by ASTM D882. As used herein, "stretch ratio (%)" is defined as [ (length after stretching-length before stretching)/length before stretching ] ×100%; the evaluation mode is as follows: if the film sample shows a film stretching ratio value of more than 1000%, the optimal value is represented by 'O'; film samples exhibit film stretch values between 800 and 1000% expressed as "delta"; and the film sample exhibited a film stretch ratio value of less than 800% indicated by an "X" as being poor.

Preparation of multilayer structures

The EVOH resin pellet compositions of examples 1 to 5 and comparative examples 1 to 6, polypropylene and adhesive layer (for example18729, Alcomax limited) to form respective multilayer films of examples 1 to 5 and comparative examples 1 to 6. The multilayer film has 5 layers, specifically, EVOH pellets (I), polypropylene (II) and a binder resin (III) were fed respectively to a five-layer coextrusion film former to prepare a multilayer sheet having the following structure: (II)/(III)/(I)/(III)/(II) each had a thickness of 300/25/50/25/300 (um).

Analysis of results of examples and comparative examples

In this section, the EVOH resin pellet compositions of examples 1 to 5 and comparative examples 1 to 6 were compared with each other, and the gel pellets and the tensile strength analysis results of the films produced therefrom were examined. The specific data are shown in tables 1 and 2, respectively.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the surface peak physical volume (Vmp) of the first EVOH resin pellets contained in the EVOH resin pellet compositions of examples 1 to 5 was 0.00001 to 6um ³/um², and at the same time, the surface peak physical volume (Vmp) of the second EVOH resin pellets was 0.00015 to 20um ³/um²; so that the prepared film has good performance in gel particles and stretching rate; in other words, the film has substantially excellent processability and mechanical properties. In contrast, the EVOH resin pellet compositions of comparative examples 1-6 did not satisfy the numerical range of the surface peak portion solid volume (Vmp) of the first and second EVOH resin pellets; which results in films produced therefrom having undesirable processability and mechanical properties. Preferably, the second EVOH resin pellets of the present invention have a Vmp greater than that of the first EVOH resin pellets thereof. Preferably, the first EVOH resin pellets have a melting point of 135 to 179℃and the second EVOH resin pellets have a melting point of 180 to 198 ℃. Preferably, the ethylene content of the first EVOH resin pellets is 36 to 50 mole percent, and the ethylene content of the second EVOH resin pellets is 20 to 35 mole percent.

Further comparing tables 1 and 2, it can be seen that although the first EVOH resin pellet contained in the EVOH resin pellet composition of comparative example 4, the second EVOH resin pellet contained in the EVOH resin pellet composition of comparative example 5, and the second EVOH resin pellet contained in the EVOH resin pellet composition of comparative example 6 fall within the Vmp value ranges of the first/second EVOH resin pellets defined in the present invention, respectively, none of the other EVOH resin pellets contained in these EVOH resin pellet compositions fall within the corresponding Vmp value ranges. It can be appreciated that the two EVOH resin pellets contained in the EVOH resin pellet composition can have desirable processability and mechanical properties after being mixed and formed into a film, only if they all conform to the defined range of Vmp values.

In addition, the inventors found that the desired surface peak portion solid volume (Vmp) of the present invention can be further controlled and obtained by controlling the production factor of the centrifugation and washing process during the processing of EVOH resin pellets; specifically: without being limited by any theory, the solid volume of the wave crest part of the surface of the EVOH resin particles is improved to a certain extent due to the over-high rotation speed of the dehydrator, the over-low water/wet particle ratio during conveying and water washing, the over-high rotation speed of the conveying pump when the centrifugal pump is closed during conveying, the over-high water flow speed and the like; conversely, too low rotational speed of the dehydrator, too high water/wet particle ratio during transportation and water washing, too low rotational speed of the centrifugal pump during transportation and too slow water flow speed and the like can cause the solid volume reduction of the surface peak part of the EVOH resin particles to a certain extent; in the specific embodiment, the rotational speed of the dehydrator is preferably controlled to be 1000-5000 rpm, the water/wet particle ratio during transportation and water washing is preferably controlled to be 3-10, the rotational speed of the centrifugal pump during transportation is preferably not more than 5000rpm during the closed state, the rotational speed of the centrifugal pump during transportation is preferably not less than 1000rpm during the open state, the water flow speed during water washing is 2-7 m/min, the rotational speed of the dehydrator for the second time is preferably controlled to be 1000-4000 rpm, and the desired solid volume of the surface wave crest part of the EVOH resin particles can be obtained.

All ranges provided herein are intended to include each specific range within the given range as well as combinations of sub-ranges between the given ranges. Moreover, unless otherwise indicated, all ranges provided herein include the endpoints of the ranges. Thus, ranges 1-5 specifically include 1,2,3, 4, and 5, as well as subranges such as 2-5, 3-5, 2-3, 2-4, 1-4, and the like.

All publications and patent applications cited in this specification are herein incorporated by reference and for any and all purposes, each individual publication or patent application is specifically and individually indicated to be incorporated by reference. In the event of an inconsistency between the present disclosure and any of the publications or patent applications incorporated by reference herein, the present disclosure shall control.

The terms "comprising," "having," "including," and "containing" are used herein in an open, non-limiting sense. The terms "a" and "an" are to be construed to cover both the plural and the singular. The term "one or more" means "at least one" and thus may include a single feature or a mixture/combination of features. The term "between" encompasses both of its end points.

Except in the operating examples, or where otherwise indicated, all numbers expressing amounts of ingredients and/or reaction conditions can be modified in all instances by the term "about," meaning within + -5% of the indicated number. The term "substantially free" or "substantially free" as used herein refers to less than about 2% of a particular feature. All elements or features that are positively set forth herein are negatively excluded from the claims.

[ Symbolic illustration ] none.

[ Biological Material deposit ].

Claims

1. An ethylene vinyl alcohol copolymer (EVOH) resin particle composition comprising:

The first EVOH resin particle has a surface peak volume (Vmp) of 0.00001 to 6 um ³ /um ² , and

The second EVOH resin particle has a surface peak volume (Vmp) of 0.00015 to 20 um ³ /um ² ,

wherein the ethylene content of the first EVOH resin particles is 36 to 50 mol percent, and the ethylene content of the second EVOH resin particles is 20 to 35 mol percent;

The Vmp of the second EVOH resin particles is greater than the Vmp of the first EVOH resin particles.

2. The EVOH resin particle composition according to claim 1, wherein the melting point of the first EVOH resin particles is 135 to 179°C, and wherein the melting point of the second EVOH resin particles is 180 to 198°C.

3. The EVOH resin particle composition according to claim 1 or 2, wherein the EVOH resin particles are in the shape of a cylinder, an elliptical cylinder, an angular cylinder, a sphere, an elliptical sphere or a go shape, and have a major diameter/height of 1 to 5 mm and a minor diameter of 1 to 5 mm.

4 . The EVOH resin particle composition according to claim 1 , wherein the weight percentage of the first EVOH resin particles to the second EVOH resin particles is 5:95 to 75:25.

5. The EVOH resin pellet composition according to claim 1 or 2, which has a boron content of 5 to 550 ppm.

6. The EVOH resin pellet composition according to claim 1 or 2, which has an alkali metal content of 10 to 550 ppm.

7. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0020 to 25; and

The second EVOH resin particles have a kurtosis (Sku) surface parameter of 0.0070 to 111.

8. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a surface parameter of a maximum peak height (Sp) of 0.0005 to 29 μm; and

The second EVOH resin particles have a surface parameter of a maximum peak height (Sp) of 0.0020 to 63 μm.

9. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a surface parameter of a protruding peak height (Spk) of 0.001 to 2 um; and

The second EVOH resin particles have a surface parameter of a protruding peak height (Spk) of 0.003 to 22 μm.

10. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a surface parameter of a peak height (Sxp) of 0.001 to 12 um; and

The second EVOH resin particles have a pole height (Sxp) surface parameter of 0.002-48 um.

11. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a surface parameter of a linear arithmetic average height (Ra) of 0.001 to 0.990 um; and

The second EVOH resin particles have a surface parameter of a linear arithmetic average height (Ra) of 0.001 to 0.990 um.

12. The EVOH resin particle composition according to claim 1 or 2, wherein:

The first EVOH resin particles have a line maximum height (Rz) surface parameter of 0.0010 to 9.9000 um; and

The second EVOH resin particles have a line maximum height (Rz) surface parameter of 0.0010 to 9.9000 um.

13. An ethylene-vinyl alcohol copolymer film, which is formed from the EVOH resin particle composition according to any one of claims 1 to 12.

14. A multilayer structure comprising:

(a) at least one layer of an ethylene-vinyl alcohol copolymer film formed from the EVOH resin particle composition according to any one of claims 1 to 12;

(b) at least one polymer layer; and

(c) at least one adhesive layer.

15. The multilayer structure of claim 14, wherein the polymer layer is selected from the group consisting of a low density polyethylene layer, a polyethylene grafted maleic anhydride layer, a polypropylene layer, and a nylon layer, and the adhesive layer is a tie layer.

16. The multilayer structure according to claim 14 or 15, wherein the multilayer structure is polymer layer/adhesive layer/ethylene-vinyl alcohol copolymer film/adhesive layer/polymer layer.