TW202300587A - Ethylene vinyl alcohol copolymer resin composition, ethylene vinyl alcohol copolymer film formed therefrom, as well as multilayer structure containing the same - Google Patents

Abstract

The instant disclosure relates to an ethylene vinyl alcohol copolymer (EVOH) resin composition, an EVOH film formed therefrom, and a multilayer structure containing the same. The surface roughness of the EVOH resin composition isthe peak material volume (Vmp) between 0.0008 and 10 μm ³/μm ². The EVOH of the present invention can reduce the torque output during processing, and can obtain the EVOH film with excellent appearance.

Description

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

The invention relates to an ethylene-vinyl alcohol copolymer (ethylene-vinyl alcohol, EVOH) resin composition. The ethylene-vinyl alcohol copolymer resin composition has high surface uniformity, especially the surface roughness is between 0.0008 and 10 μm ³ /μm ² and the volume of peak portion (Vmp). The present invention also discloses a film formed from the EVOH resin composition and a multilayer structure comprising the EVOH resin composition.

EVOH resin is widely used in multilayer bodies for preserving perishable items. For example, EVOH resins and multilayers are commonly used in the food packaging industry, medical equipment and consumables industry, pharmaceutical industry, electronics industry, and agricultural chemical industry. EVOH resins are commonly used in multilayer bodies as a unique layer to serve as an oxygen barrier layer.

It is currently known that EVOH particles formed by EVOH resin have large surface roughness and high friction between particles, resulting in extremely high torque during EVOH processing. Although the processability of EVOH has been adjusted by adding a slip agent in the past, there is still a need for further improvement.

In view of the continuing need for EVOH resin compositions that provide reduced torque output during processing and achieve high surface uniformity.

The present invention relates to an ethylene-vinyl alcohol copolymer (EVOH) resin composition having high surface uniformity, wherein the ethylene-vinyl alcohol copolymer resin composition comprises an ethylene-vinyl alcohol copolymer resin, for example, said The surface roughness of the EVOH resin composition ranges from 0.0008 to 10 μm ³ /μm ² of the peak volume (Vmp). In addition, the surface roughness of the EVOH resin composition can further be a core solid volume (Vmc) between 0.005 and 50 μm ³ /μm ² , and/or a maximum peak height (Sp) between 0.005 and 7 μm. ). The EVOH resin composition can be in the form of particles, films, fibers, and the like. The EVOH resin composition can be used to prepare films or multilayer structures. The inventors found that by controlling the surface roughness of the EVOH resin composition, the torque output during EVOH processing can be reduced, and the film formed from the EVOH resin composition and the multilayer structure comprising the EVOH resin composition have excellent appearance.

In addition/or, the maximum line height (Rz) of the surface of the EVOH resin composition is about 0.01-13 μm; or the Rz of the surface of the EVOH resin composition is 0.01-9.9 μm.

In a non-limiting example, the moisture content of the EVOH resin composition is less than 1 weight percent.

In other aspects of the present invention, there is provided an EVOH resin composition (or its particles) having a boron content ranging from 5-550 ppm. The EVOH resin composition may have an alkali metal content of about 5-550 ppm. In addition/or, the EVOH resin composition may further include one or a combination of the group consisting of cinnamic acid, conjugated polyene, lubricant and alkaline earth metal.

Additionally/alternatively, the ethylene-vinyl alcohol copolymer resin in the EVOH resin composition may have a saponification degree of 99.5 mole% or higher. The ethylene-vinyl alcohol copolymer resin in the EVOH resin composition may have an ethylene content of about 20 to about 48 mole%. For example, the ethylene-vinyl alcohol copolymer may have an ethylene content of about 25 to about 45 mole percent. . The EVOH resin composition can be formed from two or more EVOHs having different ethylene contents.

According to at least one embodiment, the multilayer structure includes: (a) at least one layer formed of the aforementioned ethylene-vinyl alcohol copolymer resin; (b) at least one polymer layer; and (c) at least one adhesive layer . The polymer layer may be, for example, selected from the group consisting of a low density polyethylene layer, a polyethylene grafted maleic anhydride layer, a polypropylene layer and a nylon layer. The adhesive layer is a tie layer.

The present invention relates to an ethylene-vinyl alcohol copolymer (EVOH) resin composition. The EVOH resin composition has a low surface roughness, especially the surface roughness is between 0.0008 and 10 μm ³ /μm ² of the volume of peak portion (Vmp). In addition, the surface roughness of the EVOH resin composition can further be a core solid volume (Vmc) between 0.005-50 μm ³ /μm ² and/or a maximum peak height (Sp) between 0.005-7 μm. The control of the surface roughness of the EVOH resin composition can be achieved by adjusting the washing stage after granulation in the EVOH process, so that the EVOH resin composition and its film have good efficacy. The EVOH resin composition can be used to prepare films or multilayer structures. The inventors found that by controlling the surface roughness parameter Vmp of EVOH particles within a specific range, the torque output during EVOH processing can be reduced, and the gel formation of the film and multilayer structure formed therefrom can be improved.

The definition of the peak volume (Vmp) refers to ISO 25178:2012, which is to quantify the size of the protruding peak with the volume parameter. When using the volume parameter, the load area ratio separating the core and the protruding peak must be specified, and the core The load area ratios of the bottom part and the protruding trough part are usually specified as 10% and 80%, respectively. The surface roughness Vmp is preferably between 0.0008 and 10 μm ³ /μm ² , and the Vmp can be, for example: between 0.0008 and 10 μm ³ /μm ² , between 0.0008 and 9 μm ³ /μm ² , between 0.0008 to 8 μm ³ /μm ² , between 0.0008 and 7 μm ³ /μm ² , between 0.0008 and 6 μm ³ /μm ² , between 0.0008 and 5 μm ³ /μm ² , between 0.0008 and 4 μm ³ /μm ² , between 0.0008 to 3 μm ³ /μm ² , 0.0008 to 2 μm ³ /μm ² , 0.0008 to 1 μm ³ /μm ² , 0.0008 to 0.1 μm ³ /μm ² , 0.0008 to 0.01 μm ³ /μm ² , Between 0.0008 and 0.001 ^{μm 3} /μm ² , between 0.001 and 10 μm ³ /μm ² , between 0.001 and 9 μm ³ /μm ² , between 0.001 and 8 μm ³ /μm ² , between 0.001 and 7 μm ³ /μm ² , between 0.001 and 6 μm ³ /μm ² , between 0.001 and 5 μm ³ /μm ² , between 0.001 and 4 μm ³ /μm ² , between 0.001 and 3 μm ³ /μm ² , between 0.001 and 2 μm ³ /μm ² , between 0.001 and 1 μm ³ /μm ² , between 0.001 and 0.1 μm ³ /μm ² , between 0.001 and 0.01 μm ³ /μm ² , between 0.1 and 10 μm ³ /μm ² , between 0.1 and 9 μm ³ / μm ² , between 0.1 and 8 μm ³ /μm ² , between 0.1 and 7 μm 3 /μm ^{2 , between 0.1 and 6 μm 3 /μm 2 , between 0.1} and 5 μm ³ /μm ² , between 0.1 and 4 μm ³ / μm ² , between 0.1 and 3 μm ³ /μm ² , between 0.1 and 2 μm ³ /μm ² , between 0.1 and 1 μm ³ /μm ² , between 0.8 and 10 μm ³ /μm ² , between 0.8 and 9 μm ³ / μm ² , between 0.8 and 8 μm ³ /μm ² , between 0.8 and 7 μm 3 /μm ² , between 0.8 and 6 ^{μm 3 /} μm ² , between 0.8 and 5 μm ³ /μm ² , between 0.8 and 4 μm ³ / μm ² , between 0.8 and 3 μm ³ /μm ² , between 0.8 and 2 μm ³ /μm ² , between 0.8 and 1 μm ³ /μm ² , between 2 and 10 μm ³ /μm ^2. Between 2 and 9 μm ³ /μm ² , between 2 and 8 μm ³ /μm ^{2 , between 2 and 7 μm 3 /μm 2} , between 2 and 6 ^{μm 3 / μm 2 ,} between 2 and 5 μm ³ /μm ^2. Between 2 and 4 μm ³ /μm ² , between 4 and 10 μm ³ /μm ² , between 4 and 9 μm ³ /μm ² , between 4 and 8 μm ³ /μm ² , between 4 and 7 μm ³ /μm ^2. Between 4 and 6 μm ³ /μm ² , between 6 and 10 μm ³ /μm ² , between 6 and 9 μm ³ /μm ² , between 6 and 8 μm ³ /μm ² , between 8 and 10 μm ³ /μm ² or between 9 and 10 μm ³ /μm ² .

The definition of the solid volume of the core (Vmc) refers to ISO 25178:2012. It uses the volume parameter to quantify the size of the core, just like the description of the solid volume of the peak. When using the volume parameter, it must be specified to separate the core and the prominent peak The load area ratio of the core part and the load area ratio of the protruding trough part are usually specified as 10% and 80% respectively. The surface roughness Vmc is preferably between 0.005 and 50 μm ³ /μm ² , and the Vmc can be, for example: between 0.005 and 50 μm ³ /μm ² , between 0.005 and 45 μm ³ /μm ² , between 0.005 to 40 μm ³ /μm ² , between 0.005 and 35 μm ³ /μm ² , between 0.005 and 30 μm ³ /μm ² , between 0.005 and 25 μm ³ /μm ² , between 0.005 and 20 μm ³ /μm ² , between 0.005 to 15 μm ³ /μm ² , between 0.005 and 10 μm ³ /μm ² , between 0.005 and 5 μm ³ /μm ² , between 0.005 and 1 μm ³ /μm ² , between 0.005 and 0.1 μm ³ /μm ² , between Between 0.005 and 0.01 μm ³ /μm ² , between 0.01 and 50 μm ³ /μm ² , between 0.01 and 45 μm ³ /μm ² , between 0.01 and 40 μm ³ /μm ² , between 0.01 and 35 μm ³ /μm ² , 0.01 to 30 μm ³ /μm ² , 0.01 to 25 μm ³ /μm ² , 0.01 to 20 μm ³ /μm ² , 0.01 to 15 μm ³ /μm ² , 0.01 to 10 μm ³ /μm ² , Between 0.01 and 5 μm ³ /μm ² , between 0.01 and 1 μm ³ /μm ² , between 0.01 and 0.1 μm ³ /μm ² , between 1 and 50 μm ³ /μm ² , between 1 and 45 μm ³ /μm ² , between 1 and 40 μm ³ /μm ² , between 1 and 35 μm ³ /μm ² , between 1 and 30 μm ³ /μm ² , between 1 and 25 μm ³ /μm ² , between 1 and 20 μm ³ /μm ² , between 1 and 15 μm ³ /μm ² , between 1 and 10 μm ³ /μm ² , between 1 and 5 μm ³ /μm ² , between 5 and 50 μm ³ /μm ² , between 5 and 45 μm ³ /μm ² , between 5 and 40 μm ³ /μm ² , between 5 and 35 μm ³ /μm ² , between 5 and 30 μm ³ /μm ² , between 5 and 25 μm ³ /μm ² , between 5 and 20 μm ³ /μm ² , between 5 and 15 μm ³ /μm ² , between 5 and 10 μm ³ /μm ² , between 10 and 50 μm ³ /μm ² , between 10 and 45 μm ³ /μm ² , between 10 and 40 μm ³ /μm ² , between 10 and 35μm ³ /μm ^2. Between 10 and 30 μm ³ /μm ² , between 10 and 25 μm ³ /μm ² , between 10 and 20 μm ³ /μm ² , between 10 and 15 μm ³ /μm ² , between 10 and 10 μm ³ /μm ^2. Between 20 and 50 μm ³ /μm ² , between 20 and 45 μm ³ /μm ² , between 20 and 40 μm ³ /μm ² , between 20 and 35 μm ³ /μm ² , between 20 and 30 μm ³ /μm ^2. Between 20 to 25 μm ³ /μm ² , between 30 to 50 μm ³ /μm ² , between 30 to 45 μm ³ /μm ² , between 30 to 40 μm ³ /μm ² , between 35 to 50 μm ³ /μm ^2. Between 35 to 45 μm ³ /μm ² , between 35 to 40 μm ³ /μm ² , between 40 to 50 μm ³ /μm ² or between 40 to 45 μm ³ /μm ² .

The maximum peak height (Sp) is the maximum peak height of the surface, and its definition refers to ISO 25178:2012, which is the height of the highest point in the defined range. The surface roughness Sp is preferably between 0.005 and 7 μm, and the Sp can be, for example: between 0.005 and 7 μm, between 0.005 and 6 μm, between 0.005 and 5 μm, between 0.005 and 4 μm, between 0.005 to 3 μm, between 0.005 and 2 μm, between 0.005 and 1 μm, between 0.005 and 0.1 μm, between 0.005 and 0.01 μm, between 0.01 and 7 μm, between 0.01 and 6 μm, between 0.01 and 5 μm, between 0.01 to 4 μm, 0.01 to 3 μm, 0.01 to 2 μm, 0.01 to 1 μm, 0.01 to 0.1 μm, 0.1 to 7 μm, 0.1 to 6 μm, 0.1 to 5 μm, 0.1 to 4 μm, between 0.1 to 3 μm, between 0.1 to 2 μm, between 0.1 to 1 μm, between 1 to 7 μm, between 1 to 6 μm, between 1 to 5 μm, between 1 to 4 μm, between 1 to 3 μm , between 1 to 2 μm, between 2 to 7 μm, between 2 to 6 μm, between 2 to 5 μm, between 2 to 4 μm, between 2 to 3 μm, between 4 to 7 μm, between 4 to 6 μm or between at 4 to 5 μm.

In one aspect, the present invention provides an EVOH resin composition. The EVOH resin composition can be in the form of particles, films, fibers, and the like. The EVOH granules described herein refer to the form and/or shape of one or more granules formed from the EVOH resin composition after granulation. Although throughout this disclosure the EVOH resin composition is described as being pelletized to form one or more EVOH particles, the EVOH resin composition may be processed into beads, cubes, chips, shavings, and the like. In some embodiments, the EVOH resin composition is in the form of particles, which can be columnar, granular or flat. The round granular shape can be spherical, ellipsoidal or go-shaped, and the columnar shape can be cylindrical, elliptical cylindrical, or angular cylindrical.

When the EVOH particles are spherical, ellipsoidal or Go-shaped, the maximum outer diameter of the particle is used as the long side, and the maximum diameter in the cross-section perpendicular to the long side is the short side. The range of the long side can be between 0.5~6.0 mm, 2.2~5.0 mm, 2.4~5.0 mm, 2.6~5.0 mm, 2.8~5.0 mm, 3.0~5.0 mm, 3.2~5.0 mm, 3.4~5.0 mm, 3.6~ 5.0 mm, 3.8~5.0 mm, 4.0~5.0 mm, 2.0~4.5 mm, 2.0~4.4 mm, 2.0~4.2 mm, 2.0~4.0 mm, 2.0~3.8 mm, 2.0~3.6 mm, 2.0~3.4 mm, 2.0~ 3.2 mm, 2.0~3.0 mm; the range of its short side can be between 0.5~6.0 mm, 1.8~4.6 mm, 2.4~4.6 mm, 2.6~4.6 mm, 2.8~4.6 mm, 3.0~4.6 mm, 3.2~4.6 mm, 3.4~4.6 mm, 3.6~4.6 mm, 3.8~4.6 mm, 4.0~4.6 mm, 1.6~4.5 mm, 1.6~4.4 mm, 1.6~4.2 mm, 1.6~4.0 mm, 1.6~3.8 mm, 1.6~3.6 mm mm, 1.6~3.4mm, 1.6~3.2mm, 1.6~3.0mm.

When EVOH particles are cylindrical or elliptical, their height can range from 1.5~5.0 mm, 1.7~5.0 mm, 2.2~5.0 mm, 2.4~5.0 mm, 2.6~5.0 mm, 2.8~5.0 mm, 3.0~5.0 mm, 3.2~5.0 mm, 3.4~5.0 mm, 3.6~5.0 mm, 3.8~5.0 mm, 4.0~5.0 mm, 1.7~4.5 mm, 1.7~4.4 mm, 1.7~4.2 mm, 1.7~4.0 mm, 1.7~3.8 mm, 1.7~3.6 mm, 1.7~3.4 mm, 1.7~3.2 mm, 1.7~3.0 mm; the long axis range of its cross-sectional area can be between 1.5~5.0 mm, 1.7~5.0 mm, 2.2~5.0 mm , 2.4~5.0 mm, 2.6~5.0 mm, 2.8~5.0 mm, 3.0~5.0 mm, 3.2~5.0 mm, 3.4~5.0 mm, 3.6~5.0 mm, 3.8~5.0 mm, 4.0~5.0 mm, 1.7~4.5 mm , 1.7~4.4 mm, 1.7~4.2 mm, 1.7~4.0 mm, 1.7~3.8 mm, 1.7~3.6 mm, 1.7~3.4 mm, 1.7~3.2 mm, 1.7~3.0 mm.

The surface roughness characteristics of the EVOH resin composition can also be determined by the maximum line height (Rz) of the surface. Its definition standard refers to JIS B 0601 (2001 version), which is the profile curve on the reference length, the highest The sum of the height of the peak and the depth of the deepest trough.

In one embodiment, the Rz of the surface of the EVOH resin composition can be between 0.01-13 μm, for example: between 0.01-13 μm, between 0.01-12 μm, between 0.01-11 μm, between 0.01 ~10 μm, between 0.01~9 μm, between 0.01~8 μm, between 0.01~7 μm, between 0.01~6 μm, between 0.01~5 μm, between 0.01~4 μm, between 0.01~ 3 μm, between 0.01~2 μm, between 0.01~1 μm, between 0.01~0.1 μm, between 0.02~13 μm, between 0.02~12 μm, between 0.02~11 μm, between 0.02~10 μm, between 0.02~9 μm, between 0.02~8 μm, between 0.02~7 μm, between 0.02~6 μm, between 0.02~5 μm, between 0.02~4 μm, between 0.02~3 μm , between 0.02~2 μm, between 0.02~1 μm, between 0.02~0.1 μm, between 0.1~13 μm, between 0.1~12 μm, between 0.1~11 μm, between 0.1~10 μm, Between 0.1~9 μm, between 0.1~8 μm, between 0.1~7 μm, between 0.1~6 μm, between 0.1~5 μm, between 0.1~4 μm, between 0.1~3 μm, between Between 0.1~2 μm, between 0.1~1 μm, between 1~13 μm, between 1~12 μm, between 1~11 μm, between 1~10 μm, between 1~9 μm, between 1~8 μm, between 1~7 μm, between 1~6 μm, between 1~5 μm, between 1~4 μm, between 1~3 μm, between 1~2 μm, between 5 ~13 μm, between 5~12 μm, between 5~11 μm, between 5~10 μm, between 5~9 μm, between 5~8 μm, between 5~7 μm, between 7~ 13 μm, between 7~12 μm, between 7~11 μm, between 7~10 μm, between 7~9 μm, between 7~8 μm, between 8~13 μm, between 8~12 μm μm, between 8~11 μm, between 8~10 μm, between 8~9 μm, between 10~13 μm or between 10~12 μm. In a preferred embodiment, the Rz of the surface ranges from about 0.01 to about 9.9 μm.

The EVOH particles are formed from an EVOH having an ethylene content. For example, the ethylene content of the EVOH can be about 20 to about 48 mole%, about 20 to about 45 mole%, about 25 to about 45 mole%, about 28 to about 42 mole%, or about 30 to about 40 mole%. The EVOH resin composition can be formed from two or more EVOHs having different ethylene contents. For example, the ethylene content of one of the EVOHs can range from about 20 to about 35 mole%, such as about 24 to about 35 mole%, about 28 to about 35 mole%, about 20 to about 32 mole%, about 24 to About 32 mole%, about 28 to about 32 mole%, about 20 to about 30 mole%, or about 24 to about 30 mole%. Additionally/alternatively, one of the EVOHs may have an ethylene content in the range of about 36 to about 48 mole%, such as about 40 to about 48 mole%, about 44 to about 48 mole%, about 36 to about 45 mole%, or about 40 to about 45 mole%. However, in some preferred embodiments, the EVOH resin composition is formed from a single EVOH having an ethylene content of about 20 to about 48 mole%.

Additionally/or, the saponification degree of EVOH in the EVOH resin composition may be 90 mole% or higher, preferably 95 mole% or higher, preferably 97 mole% or higher, preferably 99.5 mole% or higher.

The EVOH resin composition may contain boron compound and/or boric acid and/or cinnamic acid and/or alkali metal and/or conjugated polyene and/or lubricant and/or alkaline earth metal, its salt and/or or a mixture thereof. The above substances can impart better properties to the EVOH resin composition.

In other aspects of the present invention, a kind of EVOH resin composition (or its particle) can comprise an ethylene-vinyl alcohol copolymer; And a boron compound, wherein the boron content of the ethylene-vinyl alcohol copolymer resin composition is between About 5-550ppm. In some cases, the boron content of the EVOH resin composition can be based on the total weight of the EVOH resin composition: between about 5-550 ppm, between about 5-500 ppm, between about 5-450 ppm, between Between about 5-400 ppm, between about 5-350 ppm, between about 5-300 ppm, between about 5-250 ppm, between about 5-200 ppm, between about 5-150 ppm, between about 5-100 ppm, between about 5-50 ppm, between about 10-550 ppm, between about 10-500 ppm, between about 10-450 ppm, between about 10-400 ppm, between about 10- 350 ppm, about 10-300 ppm, about 10-250 ppm, about 10-200 ppm, about 10-150 ppm, about 10-100 ppm, about 10-50 ppm , between about 50-550 ppm, between about 50-500 ppm, between about 50-450 ppm, between about 50-400 ppm, between about 50-350 ppm, between about 50-300 ppm, between At about 50-250 ppm, between about 50-200 ppm, between about 50-150 ppm, between about 50-100 ppm, between about 100-550 ppm, between about 100-500 ppm, between about 100-450 ppm, between about 100-400 ppm, between about 100-350 ppm, between about 100-300 ppm, between about 100-250 ppm, between about 100-200 ppm, between about 100- 150 ppm, about 200-550 ppm, about 200-500 ppm, about 200-450 ppm, about 200-400 ppm, about 200-350 ppm, about 200-300 ppm , between about 200-250 ppm, between about 300-550 ppm, between about 300-500 ppm, between about 300-450 ppm, between about 300-400 ppm, between about 300-350 ppm, between At about 400-550 ppm, between about 400-500 ppm, between about 400-450 ppm, or between about 500-550 ppm. Without being bound by any particular theory, it is believed that adding a boron compound to the EVOH resin composition such that the EVOH has a boron content of 5 to 550 ppm reduces or eliminates sticking of the EVOH resin composition during extrusion through a screw extruder , and further improve the uniformity and flexibility of the film thickness. In some cases, such EVOH resin compositions can be used to clean the screw extruder during extrusion by removing, or at least partially removing, the EVOH resin previously adhering to the inner surface of the screw extruder, thereby making the material With self-cleaning function, it can further improve the uniformity of film thickness.

In some cases, 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 (such as cadmium orthoborate, cadmium tetraborate), potassium borate (such as potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate), silver borate (such as silver metaborate, tetraborate silver), copper borates (e.g. copper(II) borate, copper metaborate, copper tetraborate), sodium borates (e.g. sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate) , lead borate (such as lead metaborate, lead hexaborate), nickel borate (such as nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate), barium borate (such as barium orthoborate, barium metaborate, barium diborate , barium tetraborate), bismuth borate, magnesium borate (such as magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate), manganese borate (such as manganese (I) borate, manganese metaborate, manganese tetraborate), lithium borate (eg, lithium metaborate, lithium tetraborate, lithium pentaborate), salts thereof, or combinations thereof. Borate minerals may be included such as borax, langbenesite, boborite, gerberite, boorite/suanite and szaibelyite. Among them, borax, boric acid, and sodium borates (such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, and sodium octaborate) are preferably used.

In some cases, the EVOH resin composition may also contain alkali metals. The alkali metal source for making the EVOH resin composition of the present invention contain the above-mentioned alkali metal includes alkali metal compounds such as alkali metal oxides, alkali metal hydroxides, and alkali metal salts. They are preferably water soluble. Among these, alkali metal salts are preferred from the viewpoint of dispersibility. Alkali metal salts include, for example: inorganic salts such as carbonates, bicarbonates, phosphates, borates, sulfates, and chloride salts of alkali metals; acetates, butyrates, propionates, and heptanoates of alkali metals; Monocarboxylates with 2 to 11 carbons, such as acid salts and caprates; alkali metal oxalates, malonates, succinates, adipates, suberates, sebacates, etc. Dicarboxylates with numbers 2 to 11; carboxylates of polymerized terminal carboxyl groups with EVOH, etc. These can be used individually or in combination of 2 or more types.

Examples of alkali metals used in the invention include lithium, sodium, potassium, rubidium, and cesium. These can be used individually or in combination of 2 or more types. Among them, sodium and potassium are preferred, and sodium is particularly preferred.

The EVOH resin composition can have an alkali metal content of about 5-550 ppm, and the alkali metal content can be, for example: between 5-550 ppm, between about 5-500 ppm, between about 5-450 ppm , between about 5-400 ppm, between about 5-350 ppm, between about 5-300 ppm, between about 5-250 ppm, between about 5-200 ppm, between about 5-150 ppm, between At about 5-100 ppm, between about 5-50 ppm, between 10-550 ppm, between about 10-500 ppm, between about 10-450 ppm, between about 10-400 ppm, between about 10 -350 ppm, between about 10-300 ppm, between about 10-250 ppm, between about 10-200 ppm, between about 10-150 ppm, between about 10-100 ppm, between about 10-50 ppm, between about 50-550 ppm, between about 50-500 ppm, between about 50-450 ppm, between about 50-400 ppm, between about 50-350 ppm, between about 50-300 ppm, Between about 50-250 ppm, between about 50-200 ppm, between about 50-150 ppm, between about 50-100 ppm, between about 100-550 ppm, between about 100-500 ppm, between about 100-450 ppm, between about 100-400 ppm, between about 100-350 ppm, between about 100-300 ppm, between about 100-250 ppm, between about 100-200 ppm, between about 100 -150 ppm, between about 200-550 ppm, between about 200-500 ppm, between about 200-450 ppm, between about 200-400 ppm, between about 200-350 ppm, between about 200-300 ppm, between about 200-250 ppm, between about 300-550 ppm, between about 300-500 ppm, between about 300-450 ppm, between about 300-400 ppm, between about 300-350 ppm, Between about 400-550 ppm, between about 400-500 ppm, between about 400-450 ppm, or between about 500-550 ppm.

Additionally or alternatively, the EVOH resin composition may further include one or a combination of cinnamic acid, a conjugated polyene, a lubricant and an alkaline earth metal, or a salt thereof and/or a mixture thereof. The above-mentioned substances are common substances usually present in EVOH resin compositions to make them have better properties. If the content of the above-mentioned compound having a conjugated polyene structure is 1 to 30,000 ppm per unit weight of the EVOH resin composition, the coloring after heating can be further suppressed, and the thermal stability is more excellent. And the above-mentioned alkali metal compound or alkaline earth metal compound, if the content of the alkali metal compound or alkaline earth metal compound per unit weight of the EVOH resin composition is 1~1000ppm in terms of metal, it can become long-running moldability more excellent.

The conjugated polyenes are for example but not limited to: isoprene, 2,3-dimethyl-1,3-butadiene, 2-tert-butyl-1,3-butadiene, 1,3- Pentadiene, 2,4-dimethyl-1,3-pentadiene, 3,4-dimethyl-1,3-pentadiene, 3-ethyl-1,3-pentadiene, 2 -Methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2,5-dimethyl-2,4-hexadiene, 1 ,3-octadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1,4-diphenyl-1,3-butadiene, 1-methoxy-1,3 -butadiene, 2-methoxy-1,3-butadiene, 1-ethoxy-1,3-butadiene, 2-ethoxy-1,3-butadiene, 2-nitrate 1,3-butadiene, chloroprene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, tropone, ocimene (ocimene), ferrandrene, myrcene (myrcene), farnesene (farnesene), sorbic acid, sorbate, sorbate and other sorbic acids, rosinic acid (abietic acid), etc. are composed of two carbon-carbon double bonds Conjugated dienes composed of conjugated structures; 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol, etc. are composed of conjugated structures of three carbon-carbon double bonds The conjugated triene and the conjugated polyene may be used in combination of two or more. Preferred conjugated polyenes are sorbic acids such as sorbic acid, sorbic acid esters, and sorbic acid salts.

As the slip agent used in the present invention, higher fatty acids can be enumerated, for example: higher fatty acids such as oleic acid, lauric acid, palmitic acid, myristic acid, stearic acid, behenic acid; aluminum salts of these higher fatty acids, Metal salts of higher fatty acids such as calcium salts, zinc salts, magnesium salts, and barium salts; esters of higher fatty acids such as methyl esters, isopropyl esters, butyl esters, and octyl esters of the above-mentioned higher fatty acids; stearic acid amide, behenic acid Saturated higher fatty acid amide such as amide, oleic acid amide, unsaturated higher fatty acid amide such as erucamide, vinylbisstearamide, vinylbisoleamide, vinylbiserucamide, Amides of higher fatty acids such as dihigher fatty acid amides such as vinylbislauric acid amide can be used alone or in combination of two or more.

The EVOH resin composition is conducive to more efficient preparation of the EVOH film formed therefrom. Suitable methods and equipment for making EVOH films may include those readily understood by those of ordinary skill in the art. The inventor believes that by controlling the surface roughness of the EVOH resin composition, the EVOH resin composition can reduce the torsion in the extruder, and also reduce the gel generation of the film or multilayer structure formed by the EVOH resin composition, Improve the appearance of the film or multilayer structure formed by the EVOH resin composition.

The EVOH resin composition of the present invention usually has a specific range of water content, for example, with volatile matter as the evaluation of the water content of the EVOH resin composition, the EVOH resin composition water content can be less than 1 weight percent (wt%), less than 0.9% , less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2% or less than 0.1%, or between 0.01 and 1wt%, between 0.08 and 1wt%, between 0.05 to 1 wt% or between 0.01 to 0.5 wt%. Surprisingly, it was found that the moisture content of the EVOH resin composition must be controlled within a certain range. When the moisture content is too high, the film or multi-layer structure formed by the EVOH resin composition will cause bubbles, uneven film thickness, and increased flow marks. problems in subsequent processing. Volatile matter, analyzed using ISO 14663-2 Annex A method.

In yet another aspect, the present invention provides a multilayer structure having at least one layer formed from the EVOH resin composition of the present invention; at least one polymer layer; and at least one adhesive layer. The polymer layer system can be selected from low density polyethylene layer, polyethylene grafted maleic anhydride layer, polypropylene layer, nylon layer and combinations thereof. The adhesive layer can be a tie layer, such as ARKEMA OREVAC 18729 from ARKEMA Company. Example

The following non-limiting examples of aspects of the invention are provided primarily to illustrate the aspects of the invention and the benefits achieved therein. Example 1

A non-limiting method for preparing EVOH particles formed from the EVOH resin composition is provided below. Six non-limiting Example EVOH resin compositions (Examples EVOH 1-6) and four Comparative Example EVOH resin compositions (Comparative Example EVOH 1-4) were prepared according to methods similar to those disclosed below. However, the specific methods for preparing Example EVOH 1-6 and Comparative Example EVOH 1-4 will generally differ in one or more respects from the methods disclosed below. Example EVOH 1 Granules

Add 500 kg of vinyl acetate, 100 kg of methanol, 0.0585 kg of acetyl peroxide, and 0.015 kg of citric acid into a polymerization kettle equipped with a cooling coil, and temporarily replace the inside of the polymerization kettle with nitrogen, then replace it with ethylene and press it in until the ethylene pressure It becomes 45kg/cm ² . Under ethylene pressure, the temperature was raised to 67°C while stirring to start polymerization. Six hours after the start of the polymerization, when the polymerization rate reached 60%, 0.0525 kg of sorbic acid-conjugated polyene was added as a polymerization inhibitor. Thus, an ethylene-vinyl acetate copolymer having an ethylene structural unit content of 44 mole % 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 to obtain a methanol solution of the ethylene-vinyl acetate copolymer.

For Example EVOH 1, the component formed by polymerizing ethylene monomer and vinyl acetate monomer (ethylene-vinyl acetate copolymer, hereinafter referred to as "EVAC" polymer) was saponified to form EVOH.

Subsequently, EVOH was dissolved in an aqueous alcohol solution with a ratio of methanol to water of 60:40. The EVOH/methanol/water solution was placed at 60° C. for 1 hour to promote the dissolution of EVOH in the EVOH/methanol/water solution. The EVOH/methanol/water solution had a solids content of 41 wt%.

Afterwards, the above solution of methanol, water and EVOH was pelletized by underwater pelletization. Specifically, a pump was used to pump the aforementioned methanol, water and EVOH solution into the feed pipe at a flow rate of 120 L/min, and then sent into an input pipe with a diameter of 2.8 mm, and cut with a rotary knife at 1500 rpm to obtain Particles of EVOH. At the same time, the circulating condensed water at 5°C is used to cool the EVOH particles. Subsequently, the EVOH particles were centrifuged to separate the EVOH particles and the separated EVOH pellets were washed with water, centrifuged once more, and then the EVOH particles were immersed in a boric acid/sodium acetate solution, dried and stearin was added Calcium acid to obtain the EVOH granule final product. The EVOH spherical granules end up being granules with a long side of 2.4 mm and a short side of 1.5 mm.

The so-called centrifugation and washing steps, wherein the first dehydrator speed is 3000 rpm; the water/wet particle ratio is 10 during transportation; the type of centrifugal pump (pump) for transportation is semi-open; the speed of the delivery pump (pump) is 2000 rpm ; The weight ratio of water/wet grains is 20 during washing; the water velocity is 1 m/min during washing; Example EVOH 2 Granules

The EVOH granules used in Example EVOH 2 were prepared using a similar process to the Example EVOH 1 granules. However, when preparing the EVOH granules of Example EVOH 2, the EVOH granules were immersed in the boric acid/sodium acetate solution, and the wet granule size (long side) was 3.0 mm, and the short side was 2.4 mm; 2000 rpm; the ratio of water/wet particles during transportation is 20; the type of centrifugal pump for transportation is open; the rotation speed of the delivery pump is 4000 rpm; the ratio of water/wet particles during washing is 10; the water flow speed during washing is 1.5 m/min; The rotational speed of the second dehydrator is 3000 rpm; dry to a moisture content of 0.01%. Example EVOH 3 Granules

The EVOH granules used in Example EVOH 3 were prepared using a similar process to the Example EVOH 1 granules. However, when preparing the EVOH granules of Example EVOH 3, the EVOH granules were immersed in the boric acid/sodium acetate solution, and the wet granule particle size was 5.0 mm on the long side and 5.0 mm on the short side; the spin speed of the dehydrator for the first time was 1500 rpm ; The water/wet particle ratio is 5 when conveying; the type of centrifugal pump for conveying is open; the speed of the conveying pump is 3000 rpm; The speed of the secondary dehydrator is 1000 rpm; dry to a moisture content of 0.3%. Example EVOH 4 Granules

The EVOH granules used in Example EVOH 4 were prepared using a similar process to the Example EVOH 1 granules. However, when preparing the EVOH granules of Example EVOH 4, the EVOH granules were immersed in the boric acid/sodium acetate solution, and the wet granule particle size was 0.5 mm on the long side and 0.5 mm on the short side; the spin speed of the dehydrator for the first time was 4000 rpm ; The ratio of water/wet particles during transportation is 15; the type of centrifugal pump for transportation is semi-open; the rotation speed of the delivery pump is 1000 rpm; the ratio of water/wet particles during washing is 15; The rotation speed of the secondary dehydrator is 2000 rpm; it is dried to a moisture content of 0.5%. Example EVOH 5 Granules

The EVOH granules used in Example EVOH 5 were prepared using a similar process to the Example EVOH 1 granules. However, the ethylene content of the EVOH granules of Example EVOH 5 is 28 mole percent, and when preparing the EVOH granules of Example EVOH 5, the EVOH granules are immersed in the boric acid/sodium acetate solution, and the size of the wet granules is 2.5 mm; the rotational speed of the dehydrator for the first time is 1000 rpm; the ratio of water/wet grains during transportation is 5; the type of centrifugal pump for transportation is open; the rotational speed of the conveying pump is 3000 rpm; the ratio of water/wet grains during washing is 20; The water flow rate during washing is 3.5 m/min; the speed of the dehydrator for the second time is 3000 rpm; and the water content is dried to 0.04%. Example EVOH 6 Granules

The EVOH granules used in Example EVOH 6 were prepared using a similar process to the Example EVOH 1 granules. However, the ethylene content of the EVOH particles of Example EVOH 6 is 28 mole percent, and when preparing the EVOH particles of Example EVOH 6, the EVOH particles are immersed in the boric acid/sodium acetate solution, and the wet particle size of the long and short sides is 5 mm; the rotational speed of the dehydrator for the first time is 3000 rpm; the ratio of water/wet grains during transportation is 5; the type of centrifugal pump for transportation is semi-open; the rotational speed of the conveying pump is 4000 rpm; the ratio of water/wet grains during washing is 15 ; The water flow rate during washing is 2.5 m/min; the second spin speed of the dehydrator is 3000 rpm; dry to a moisture content of 0.05%. Comparative example EVOH 1 granules

EVOH granules for Comparative Example EVOH 1 were prepared using a similar process to Example EVOH 1 granules. Yet, when preparing the EVOH granule of comparative example EVOH 1, this EVOH granule is immersed in the boric acid/sodium acetate solution, and the long and short sides of its wet granule particle size are all 6 mm; The proportion of wet grains is 1; the type of centrifugal pump for conveying is semi-open; the speed of the conveying pump is 4000 rpm; the ratio of water/wet grains during washing is 5; the water flow speed during washing is 20 m/min; the speed of the second dehydrator at 8000 rpm; dry to a moisture content of 0.07%. Comparative Example EVOH 2 Granules

EVOH granules for Comparative Example EVOH 2 were prepared using a similar process to Example EVOH 1 granules. Yet, when preparing the EVOH granule of comparative example EVOH 2, this EVOH granule is immersed in the boric acid/sodium acetate solution, and the long and short sides of its wet granule particle size are all 1 mm; The dehydrator rotating speed is 5000 rpm for the first time; The proportion of wet grains is 10; the type of centrifugal pump for conveying is closed; the rotation speed of the conveying pump is 7000 rpm; the ratio of water/wet grains during washing is 0.5; the water flow speed during washing is 5 m/min; 3000 rpm; dry to a moisture content of 0.8%. Comparative Example EVOH 3 Granules

EVOH granules for Comparative Example EVOH 3 were prepared using a similar process to Example EVOH 1 granules. Yet, when preparing the EVOH granule of comparative example EVOH 3, this EVOH granule is immersed in the boric acid/sodium acetate solution, and the long and short sides of its wet granule particle size are all 4.5 mm; The dehydrator rotating speed is 2000 rpm for the first time; The proportion of wet grains is 50; the type of centrifugal pump for conveying is open; the speed of the conveying pump is 1000 rpm; the ratio of water/wet grains during washing is 100; the water flow speed during washing is 0.5 m/min; 1000 rpm; dry to a moisture content of 0.5%. Comparative Example EVOH 4 Granules

EVOH granules for Comparative Example EVOH 4 were prepared using a similar process to Example EVOH 1 granules. Yet, when preparing the EVOH granule of comparative example EVOH 4, this EVOH granule is immersed in the boric acid/sodium acetate solution, and the long and short sides of its wet granule particle size are all 5.1 mm; The dehydrator rotating speed is 3000 rpm for the first time; The proportion of wet grains is 3; the type of centrifugal pump for conveying is semi-open; the rotation speed of the conveying pump is 3000 rpm; the ratio of water/wet grains during washing is 8; the water flow speed during washing is 10 m/min; at 3000 rpm; dry to a moisture content of 0.4%. Example 2

Films were formed using the particles of Example EVOH 1-6, respectively, according to the method described below. The Example EVOH 1-6 granules and the Comparative Example EVOH 1-4 granules were fed into a single-layer T-die casting film extruder (optical control system MEV4) to prepare a film. The thicknesses of the films formed from the particles of Example EVOH 1-6 and Comparative Example EVOH 1-4 were each 20 μm. The temperature of the extruder was set at 220°C, and the temperature of the mold (ie, T-shaped mold) was set at 230°C. The rotation frequency of the screw was 7 rpm (rotations/minutes). Example 3

The Example EVOH 1-6 granules and the Comparative EVOH 1-4 granules were evaluated to judge the properties of these EVOH granules and the films formed therefrom. Example EVOH 1-6 granules were prepared according to a method similar to that described in Example 1 above, as described above. However, the method of preparing EVOH 1-6 particles differs in that EVOH particles are prepared with different Vmp, Vmc, Sp, Rz, boron content or alkali metal content. Comparative EVOH 1-4 granules were also prepared in a manner similar to that described in Example 1.

Further evaluate the average torque and extruder current of the single-screw extruder. In a similar manner to that described in Example 2, films were formed from Example EVOH 1-6 and Comparative Example EVOH 1-4 individually, and the films were evaluated to determine the size and amount of gel (Gel) on the film.

Table 1 below provides an overview of some attributes of Example EVOH Granules 1-6 and Comparative Example EVOH Granules 1-4, namely Vmp, Vmc, Sp, Rz, boron content, alkali metal content, extruder average torque, and extruder Current, and gel generation on EVOH membranes of membranes formed from Example EVOH 1-6 and Comparative Example EVOH 1-4.

Table 1 Example EVOH 1 Example EVOH 2 Example EVOH 3 Example EVOH 4 Example EVOH 5 Example EVOH 6 technical features Solid volume of Vmp crest (μm ³ /μm ² ) 0.001 0.8 3.1 5.2 9.8 9.2 Solid volume of Vmc core (μm ³ /μm ² ) 0.01 4.3 10.6 22.3 39.5 35.4 Sp maximum peak height (μm) 0.01 0.35 1.0 2.2 4.7 4.1 Maximum height of Rz line (μm) 0.02 0.899 9.34 0.644 5.41 12.35 Boron content (ppm) 50 150 280 10 500 430 Sodium content (ppm) 10 70 500 430 220 370 effect 0~100μm Gel o o o o o o 100~200μm Gel o o o o o Δ ＞200μm Gel o o o o o o Average torque of single screw extruder (Torque) twenty one 15 33 41 twenty four 63 Single screw extruder current(Å) 33 26.2 48 65 42 71.4

Table 1 (continued) Comparative example EVOH 1 Comparative example EVOH 2 Comparative example EVOH 3 Comparative example EVOH 4 technical features Solid volume of Vmp crest (μm ³ /μm ² ) 22.3 44.6 0.0005 12.1 Solid volume of Vmc core (μm ³ /μm ² ) 66.4 110.3 0.004 72.3 Sp maximum peak height (μm) 12 15 0.0005 8.2 Maximum height of Rz line (μm) 11.05 29.73 0.01 3.66 Boron content (ppm) 180 220 170 50 Sodium content (ppm) 80 500 240 360 effect 0~100μm Gel o o x o 100~200μm Gel x x o x ＞200μm Gel x x o o Average torque of single screw extruder (Torque) 133 169 10 78.9 Single screw extruder current(Å) 271 312 11 92.1

The boron content of each embodiment and comparative example is measured by the following method. First, 0.1 g of EVOH particle samples were decomposed using concentrated nitric acid and microwave to make EVOH particles form a sample solution. The sample solution was then diluted with pure water to adjust its concentration to 0.75 mg/ml. Use an inductively coupled plasma emission spectrochemical analyzer (ICP emission spectrochemical analysis device, ICP-OES; Analyzer: iCAP7000 (Thermo Fisher Scientific, Thermo) to measure the boron content in the sample solution. The boron content refers to Corresponds to the measured value derived from the boron content of the boron compound used.

In addition, the alkali metal content in the EVOH pellets of each Example and Comparative Example was also measured. Take 2g of the above-mentioned EVOH particles to a platinum dish, add several mL of sulfuric acid, and heat with a gas burner. After confirming that the particles are carbonized and the white smoke of sulfuric acid disappears, add a few drops of sulfuric acid and reheat. Repeat this until the organic matter is gone, allowing it to ash completely. The ashed container was left to cool, and 1 mL of hydrochloric acid was added to dissolve it. This hydrochloric acid solution was washed with ultrapure water, and the volume was adjusted to 50 mL. The alkali metal content in this sample solution was measured with an inductively coupled plasma spectrometer (ICP-AES) (manufactured by Agilent Technology, Model 720-ES). Finally, the alkali metal content in the EVOH composition pellets was converted from the alkali metal concentration in the solution.

In order to evaluate the granule surface roughness of embodiment EVOH 1-6 and comparative example EVOH 1-4, EVOH granule is placed flatly on the plate top, measure granule surface roughness, need exclude the data when inclination is greater than 0.5 during measurement, to ensure The scanning plane is in a relatively horizontal state (inclination = maximum surface height Sz/side length of the analysis range 129 μm). The laser microscope was LEXT OLS5000-SAF manufactured by Olympus, and the images were made at an air temperature of 24±3°C and a relative humidity of 63±3%. The filter is set to no filter. The light source is a 405 nm-wavelength light source. The objective lens is 100x magnification (MPLAPON-100xLEXT). Optical zoom was set to 1.0x. The image area is set to 129 µm x 129 µm (when measuring Rz, take the centerline of the image area). Resolution is set to 1024px x 1024px. Measure the value of 100 particles and take the average value. Among them, Vmp, Vmc and Sp are measured by ISO 25178:2012 method; Rz is measured by JIS B 0601 (2001) method.

Example EVOH 1-6 and comparative example EVOH 1-4 were calculated by extruder torque calculation and current calculation during processing, and when EVOH particles were extruded by a single-screw extruder (model ME25/5800V4, brand OCS), measure The extruder torque value and current value, the extrusion conditions are as follows: the screw temperature is Zone1 195°C, Zone2 215°C, Zone3 220°C, Zone4 230°C, Zone5 230°C; the screw speed is 7 rpm. The calculation time is from 10 to 60 minutes, record 1 point every minute, and calculate the average value.

The results show that Example EVOH 1-6 has lower torque output (15 to 41 Torque) and current (26.2 to 65Å), showing that Example EVOH 1-6 has excellent processing torque output performance.

In addition, for the calculation of the gel/glue (Gel) of the film formed by the EVOH 1-6 of the embodiment and the EVOH 1-4 of the comparative example, after the EVOH is processed into a single-layer film, the FSA-100 film quality test system is used to analyze The number of Gel in the monolayer film is evaluated by the evaluation standard. If the number of gels < 100 μm is < 450, "O" is the best; if the number of gels < 100 μm is 450-1000, it is acceptable by "Δ"; If the quantity is more than 1000, "X" is used to indicate that it is not good. If the number of 100-200 μm gels is less than 50, "O" is the best; if the number of 100-200 μm gels is 50-100, it is acceptable to use "Δ"; If the number of gels is >100, then "X" means poor. If the number of gels >200 μm is less than 10, "O" is the best; if the number of gels >200 μm is 10-20, it is acceptable; if the number of gels >200 μm is 10-20, it is acceptable; If the quantity is > 20, it is indicated by "X" as unsatisfactory.

In the examples EVOH 1-6, the number of gels <100 μm is less than 450, the number of gels of 100-200 μm is less than 100, and the number of gels >200 μm is less than 10, showing excellent characteristics.

The inventors found that when the surface roughness of EVOH particles is too high, when the particles are rubbed during single-screw processing, local overheating is likely to cause crosslinking, and large gels are likely to be generated during processing. When the surface roughness of EVOH particles is too low, the friction heat of EVOH cannot be melted due to insufficient friction during processing, and tiny gels will be produced after extrusion. Therefore, it is necessary to control the surface roughness of EVOH particles within a certain range to avoid gelation.

By comparing the examples and comparative examples in Table 1, the inventors found that the manufacturing method variable of adjusting and controlling the washing procedure during EVOH particle processing, that is, controlling the variable factor of immersing EVOH particles in boron/sodium acetate solution, can obtain the desired effect of the present invention. Surface roughness, with the following properties: ● Particles that are too large or too small are likely to collide with each other and cause friction when transported in water; ● Excessive speed of the dehydrator, low ratio of water/wet grains, closed centrifugal pump for conveying, high rotational speed of the delivery pump, too fast water flow, etc. will cause the wet grains to collide and rub against each other during the washing process.

In Comparative Example 1, due to the large particle size, the low water/wet particle ratio during transportation, and the high speed of the second dehydrator, the wet particle has high friction and roughness increases. In Comparative Example 2, the particle size was too small, the spin speed of the dehydrator was too high for the first time, a closed centrifugal pump was used, the delivery pump speed was too high, and the water/wet material ratio was too low during washing, resulting in high friction of wet grains and increased roughness. In comparative example 3, the ratio of water/wet particles during transportation is too high, the speed of the delivery pump is too low, the ratio of wet particles to particles during water washing is too high, and the water flow rate is too low, resulting in insufficient particle friction and roughness.

According to the test results of the present invention, as long as the EVOH surface roughness is controlled within a specific range, the torsional current in the single-screw extruder and the gel generation of the EVOH film can be reduced. As shown in Table 1, comparative examples EVOH 1, 2 and 4 have Vmp, Vmc and Sp beyond the expected range described herein, and the test results all have higher extruder torque output and extruder current, and the like The formed film produced too much gel. Comparative example EVOH 3 has Vmp, Vmc and Sp lower than the expected range described herein, and although the test results have good torque output and current, the film formed by comparative example EVOH 3 produces too much gel, and has undesired nature.

In summary, the EVOH resin composition of the present invention has a low surface roughness, especially a Vmp whose surface roughness is between 0.0008 and 10 μm ³ /μm ² . In addition, the surface roughness of the EVOH resin composition of the present invention can further be a Vmc ranging from 0.005 to 50 μm ³ /μm ² and/or a Sp ranging from 0.005 to 7 μm. The control of the surface roughness of the EVOH resin composition can be achieved by manipulating the variables in the washing stage of the EVOH process. The EVOH resin composition can be used to prepare films or multilayer structures. The inventors have found that by controlling the surface roughness of EVOH particles, the torque output during EVOH processing can be reduced, and the excess gel produced by the film formed by EVOH can be reduced.

Herein, all ranges provided are intended to include each specific range within the given range as well as combinations of subranges between the given ranges. Additionally, unless otherwise stated, all ranges provided herein include the endpoints of the stated range. Thus, the range 1-5 specifically includes 1, 2, 3, 4, and 5, and sub-ranges such as 2-5, 3-5, 2-3, 2-4, 1-4, and so on.

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 any inconsistency between this document and any publication or patent application incorporated herein by reference, this document controls.

The terms "including", "having" and "comprising" are used herein in an open, non-limiting sense. The terms "a" and "the" should be understood 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.

Except in the working examples or where otherwise indicated, all figures expressing amounts of ingredients and/or reaction conditions are in all instances modified by the term "about", meaning within ± 5% of the indicated figure . As used herein, the term "substantially free" or "substantially free" means less than about 2% of a specified characteristic. All elements or features affirmatively stated herein may be negatively excluded from the scope of claims.

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Claims (15)

An ethylene-vinyl alcohol copolymer resin composition, which includes an ethylene-vinyl alcohol copolymer resin; wherein the ethylene-vinyl alcohol copolymer resin composition has a surface, and the surface has a ratio of 0.0008 to 10 μm ³ /μm ² Peak solid volume (Vmp). As for the ethylene-vinyl alcohol copolymer resin composition described in claim 1 of the patent application, the surface of the ethylene-vinyl alcohol copolymer resin composition has a core volume (Vmc) between 0.005 and 50 μm ³ /μm ² . As for the ethylene-vinyl alcohol copolymer resin composition described in claim 1, the surface of the ethylene-vinyl alcohol copolymer resin composition has a maximum peak height (Sp) between 0.005 and 7 μm. As for the ethylene-vinyl alcohol copolymer resin composition described in item 1 of the scope of the patent application, the ethylene-vinyl alcohol copolymer resin composition is in the form of particles. As for the ethylene-vinyl alcohol copolymer resin composition described in claim 1 of the patent application, the ethylene content of the ethylene-vinyl alcohol copolymer resin is between 20-48 mole percent. As for the ethylene-vinyl alcohol copolymer resin composition described in item 1 of the patent application, the saponification degree of the ethylene-vinyl alcohol copolymer resin is greater than 99.5 mole percent. As for the ethylene-vinyl alcohol copolymer resin composition described in any one of claims 1 to 6, the maximum line height (Rz) of the surface is between 0.01 and 13 μm. For the ethylene-vinyl alcohol copolymer resin composition described in item 7 of the patent application, the maximum line height (Rz) of the surface is between 0.01 and 9.9 μm. As the ethylene-vinyl alcohol copolymer resin composition described in any one of claims 1 to 6, the water content is less than 1% by weight. The ethylene-vinyl alcohol copolymer resin composition as described in any one of claims 1 to 6 of the patent application has a boron content of 5-550 ppm. The ethylene-vinyl alcohol copolymer resin composition as described in any one of claims 1 to 6 of the patent application has an alkali metal content of 5-550 ppm. The ethylene-vinyl alcohol copolymer resin composition as described in any one of claims 1 to 6, further comprising one of the group consisting of cinnamic acid, conjugated polyene, lubricant and alkaline earth metal or its combination. An ethylene-vinyl alcohol copolymer film is formed from the ethylene-vinyl alcohol copolymer resin composition described in any one of the patent scopes 1 to 12. A multi-layered structure comprising: (a) At least one layer is formed of the ethylene-vinyl alcohol copolymer resin of any one of the claims 1 to 12; (b) at least one polymer layer; and (c) At least one adhesive layer. The multi-layer structure as described in item 14 of the patent application, wherein the polymer layer is selected from a low-density polyethylene layer, a polyethylene grafted maleic anhydride (polyethylene grafted maleic anhydride) layer, a polypropylene layer and a nylon layer. group, and the bonding layer is a bonding layer (tie layer).