TWI767756B - 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 the same

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

EVOH resins are widely used in multilayer bodies for the preservation of perishable items. For example, EVOH resins and multilayers are commonly used in the food packaging industry, the medical device and consumables industry, the pharmaceutical industry, the electronics industry, and the agrochemical industry. EVOH resins are commonly used in multilayer bodies as a unique layer to act as an oxygen barrier.

At present, it is known that EVOH particles formed from 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 lubricants in the past, there is still a need for further improvement.

There is a 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, the The surface roughness of the EVOH resin composition is between 0.0008 and 10 μm ³ /μm ² of the physical volume of the peak (Vmp). In addition, the surface roughness of the EVOH resin composition may further be between 0.005 to 50 μm ³ /μm ² of the physical volume of the core (Vmc), and/or between 0.005 to 7 μm The maximum peak height (Sp ). The EVOH resin composition can be in the form of particles, films, fibers, and the like. The EVOH resin composition can be used to make 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/alternatively, the maximum 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 EVOH resin composition has a moisture content of less than 1 weight percent.

In other aspects of the present invention, there is provided an EVOH resin composition (or particles thereof) that may have a boron content of 5-550 ppm. The EVOH resin composition may have an alkali metal content of about 5-550 ppm. In addition/alternatively, the EVOH resin composition may further comprise one or a combination of the group consisting of cinnamic acid, conjugated polyene, slip agent and alkaline earth metal.

In addition/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 content of the ethylene-vinyl alcohol copolymer may be from about 25 to about 45 mole percent. . The EVOH resin composition system may be formed from two or more EVOHs having different ethylene contents.

According to at least one embodiment, the multi-layer structure includes: (a) at least one layer formed of the ethylene-vinyl alcohol copolymer resin as described above; (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 low surface roughness, especially the surface roughness is between 0.0008 to 10 μm ³ /μm ² of the solid volume of the peak (Vmp). In addition, the surface roughness of the EVOH resin composition may further be between 0.005 to 50 μm ³ /μm ² for the core volume (Vmc) and/or between 0.005 to 7 μm for the maximum peak height (Sp). The control of the surface roughness of the EVOH resin composition can be achieved by adjusting the washing stage after the granulation of the EVOH process, so that the EVOH resin composition and its film have good efficacy. The EVOH resin composition can be used to make 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 films and multilayer structures formed therefrom can be improved.

The definition of the physical volume of the peak part (Vmp) refers to ISO 25178:2012, which is based on the volume parameter to quantify the size of the protruding peak part. When using the volume parameter, the load area ratio that separates the core part and the protruding peak part must be specified, and the core part The load area ratios of the trough and the protruding trough 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 , 0.0008 to 7 μm 3 /μm ² , 0.0008 to 6 μm ³ /μm ² , 0.0008 to 5 μm ³ /μm ² , 0.0008 to ^{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 , 0.0008 to 0.001 μm ³ /μm ² , 0.001 to 10 μm ³ /μm ² , 0.001 to 9 μm ³ /μm ² , 0.001 to 8 μm ³ /μm ² , 0.001 to 7 μm ³ /μm ² , between 0.001 and 6μm ³ /μm ² , between 0.001 and 5μm ³ /μm ² , between 0.001 and 4μm ³ /μm ² , between 0.001 and 3μm ³ /μm ² , between 0.001 and 2μm 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 to 9 μm ³ /μm ² , Between 2 to 8 μm ³ /μm ² , Between 2 to 7 μm ³ /μm ² , Between 2 to 6 μm ³ /μm ² , Between 2 to 5 μm ³ /μm ^2. Between 2 and 4μm ³ /μm ² , Between 4 and 10μm ³ /μm ² , Between 4 and 9μm ³ /μm ² , Between 4 and 8μm ³ /μm ² , Between 4 and 7μm ³ /μm ^2. Between 4 to 6 μm ³ /μm ² , Between 6 to 10 μm ³ /μm ² , Between 6 to 9 μm ³ /μm ² , Between 6 to 8 μm ³ /μm ² , Between 8 to 10 μm ³ /μm ² or between 9 and 10 μm ³ /μm ² .

The definition of the physical volume of the core part (Vmc) refers to ISO 25178:2012, which is based on the volume parameter to quantify the size of the core part. Just like the description of the physical volume of the crest part, when using the volume parameter, it must be specified to separate the core part and the protruding crest part. The load area ratio of , and the load area ratio of the core part and 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 , 0.005 to 35 μm 3 /μm ² , 0.005 to 30 μm ³ /μm ² , 0.005 to 25 μm ³ /μm ² , 0.005 to ^{20 μm 3 /} μm ² , between 0.005 to 15 μm ³ /μm ² , 0.005 to 10 μm ³ /μm ² , 0.005 to 5 μm ³ /μm ² , 0.005 to 1 μm ³ /μm ² , 0.005 to 0.1 μm ³ /μm ² , medium at 0.005-0.01μm 3 /μm ² , between 0.01-50μm ³ /μm ² , between 0.01-45μm ³ /μm ² , between 0.01-40μm ³ /μm ² , between ^{0.01-35μm 3} /μm ² , between 0.01-30μm ³ /μm ² , between 0.01-25μm ³ /μm ² , between 0.01-20μm ³ /μm ² , between 0.01-15μm ³ /μm ² , between 0.01-10μm ³ /μm ² , between 0.01 to 5 μm ³ /μm ² , between 0.01 to 1 μm ³ /μm ² , between 0.01 to 0.1 μm ³ /μm ² , between 1 to 50 μm ³ /μm ² , between 1 to 45 μm ³ /μm ² , between 1 and 40μm ³ /μm ² , between 1 and 35μm ³ /μm ² , between 1 and 30μm ³ /μm ² , between 1 and 25μm ³ /μm ² , between 1 and 20μm ³ /μm ² , between 1 and 15μm ³ /μm ² , between 1 and 10μm ³ /μm ² , between 1 and 5μm ³ /μm ² , between 5 and 50μm ³ /μm ² , between 5 and 45μm ³ /μm ² , between 5 and 40μm ³ /μm ² , between 5 and 35μm ³ /μm ² , between 5 and 30μm ³ /μm ² , between 5 and 25μm ³ /μm ² , between 5 and 20μm ³ /μm ² , between 5 and 15μm ³ /μm ² , between 5 and 10μm ³ /μm ² , between 10 and 50μm ³ /μm ² , between 10 and 45μm ³ /μm ² , between 10 and 40μm ³ /μm ² , between 10 and 35 μm ³ /μm ^2. Between 10-30μm ³ /μm ² , Between 10-25μm ³ /μm ² , Between 10-20μm ³ /μm ² , Between 10-15μm ³ /μm ² , Between 10-10μm ³ /μm ^2. Between 20 and 50μm ³ /μm ² , Between 20 and 45μm ³ /μm ² , Between 20 and 40μm ³ /μm ² , Between 20 and 35μm ³ /μm ² , Between 20 and 30μm ³ /μm ^2. Between 20-25μm ³ /μm ² , Between 30-50μm ³ /μm ² , Between 30-45μm ³ /μm ² , Between 30-40μm ³ /μm 2 , Between 35-50μm ³ /μm ^{2 2.} Between 35 and 45 μm ³ /μm ² , between 35 and 40 μm ³ /μm ² , between 40 and 50 μm ³ /μm ² or between 40 and 45 μm ³ /μm ² .

The maximum peak height (Sp) is the maximum peak height of the surface, which is defined with reference to ISO 25178:2012, which is the height of the highest point in the definition range. The roughness Sp of the surface 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 0.005-3μm, 0.005-2μm, 0.005-1μm, 0.005-0.1μm, 0.005-0.01μm, 0.01-7μm, 0.01-6μm, 0.01-5μm, between 0.01-4μm, 0.01-3μm, 0.01-2μm, 0.01-1μm, 0.01-0.1μm, 0.1-7μm, 0.1-6μm, 0.1-5μm, 0.1 to 4μm, between 0.1 and 3μm, between 0.1 and 2μm, between 0.1 and 1μm, between 1 and 7μm, between 1 and 6μm, between 1 and 5μm, between 1 and 4μm, between 1 and 3μm , between 1-2μm, between 2-7μm, between 2-6μm, between 2-5μm, between 2-4μm, between 2-3μm, between 4-7μm, between 4-6μm 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. As used herein, EVOH particles refer to the form and/or shape of an EVOH resin composition that has been pelletized to form one or more particles. Although the EVOH resin composition is described throughout this disclosure as pelletized to form one or more EVOH pellets, the EVOH resin composition can be processed into the form of 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 particle shape can be spherical, elliptical spherical or chess shape, and the columnar shape can be cylindrical, elliptical columnar or angular columnar shape.

When EVOH particles are spherical, elliptical spherical or chess-shaped, the maximum outer diameter of the particles is taken as the long side, and the largest diameter in the cross-section with the largest area in the cross-section perpendicular to the long side is taken as 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 the 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 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, 1.6~3.4 mm, 1.6~3.2 mm, 1.6~3.0 mm.

When EVOH particles are cylindrical or elliptical, their heights 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 of the EVOH resin composition can also be characterized by the maximum height (Rz) of the surface line, which is defined by reference to JIS B 0601 (2001 version), which is the highest in the profile curve on the reference length. The sum of the height of the crest 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, 0.01~9 μm, 0.01~8 μm, 0.01~7 μm, 0.01~6 μm, 0.01~5 μm, 0.01~4 μm, 0.01~ 3 μm, 0.01~2 μm, 0.01~1 μm, 0.01~0.1 μm, 0.02~13 μm, 0.02~12 μm, 0.02~11 μm, 0.02~10 μm, 0.02~9 μm, 0.02~8 μm, 0.02~7 μm, 0.02~6 μm, 0.02~5 μm, 0.02~4 μm, 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 at 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, 1~7 μm, 1~6 μm, 1~5 μm, 1~4 μm, 1~3 μm, 1~2 μm, 5 ~13 μm, 5~12 μm, 5~11 μm, 5~10 μm, 5~9 μm, 5~8 μm, 5~7 μm, 7~ 13 μm, 7~12 μm, 7~11 μm, 7~10 μm, 7~9 μm, 7~8 μm, 8~13 μm, 8~12 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 may 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 system may be formed from two or more EVOHs having different ethylene contents. For example, one of the EVOHs may have an ethylene content in the range of 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 24 mole% 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 %.

In addition/alternatively, the degree of saponification 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 in some cases comprise boron compounds and/or boric acid and/or cinnamic acid and/or alkali metals and/or conjugated polyenes and/or lubricants and/or alkaline earth metals, salts thereof and/or or a mixture thereof. The above substances can impart better properties to the EVOH resin composition.

In another aspect of the present invention, there is provided an EVOH resin composition (or particles thereof) which may 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 5-550 ppm. In some cases, the boron content of the EVOH resin composition, based on the total weight of the EVOH resin composition, may be: between about 5-550 ppm, between about 5-500 ppm, between about 5-450 ppm, between at 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, 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 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, 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 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 to a boron content of 5 to 550 ppm in EVOH reduces or eliminates sticking of the EVOH resin composition during extrusion through the screw extruder , and further improve the uniformity and flexibility of film thickness. In some cases, such EVOH resin compositions can clean the screw extruder during extrusion by removing or at least partially removing EVOH resin previously adhering to the inner surface of the screw extruder, thereby allowing 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 (eg, zinc tetraborate, zinc metaborate), potassium aluminum borate, ammonium borate (eg, 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 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 (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, kaleite, brookite, boronite, borate/suanite, and szaibelyite. Among them, borax, boric acid and sodium borate (eg, 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 an alkali metal. The alkali metal source for containing the above-mentioned alkali metal in the EVOH resin composition of the present invention includes alkali metal compounds such as alkali metal oxides, alkali metal hydroxides, and alkali metal salts. They are preferably water-soluble. Among them, alkali metal salts are preferred from the viewpoint of dispersibility. Examples of the alkali metal salt include inorganic salts such as alkali metal carbonate, bicarbonate, phosphate, borate, sulfate, and chloride salt; alkali metal acetate, butyrate, propionate, heptyl Monocarboxylates with carbon number 2 to 11 such as acid salts and caprates; alkali metal oxalates, malonates, succinates, adipates, suberates, sebacates and other carbons Dicarboxylates of numbers 2 to 11; carboxylates with EVOH terminal carboxyl groups, etc. These can be used alone or in combination of two or more.

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

The EVOH resin composition may have an alkali metal content of about 5-550 ppm, and the alkali metal content may 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 about at 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, 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.

In addition/alternatively, the EVOH resin composition may further comprise one or a combination of the group consisting of cinnamic acid, conjugated polyene, slip agent and alkaline earth metal, or a salt thereof and/or a mixture thereof. The above-mentioned substances are common substances that are usually present in EVOH resin compositions to give them better properties. When the content of the compound having the conjugated polyene structure is 1 to 30,000 ppm per unit weight of the EVOH resin composition, coloration after heating can be further suppressed, and thermal stability is further improved. On the other hand, if the content of the alkali metal compound or alkaline earth metal compound contained in the above-mentioned EVOH resin composition is 1 to 1000 ppm in terms of metal conversion per unit weight of the EVOH resin composition, the long-term running formability can be achieved. better.

The conjugated polyenes are such as 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-nitro yl-1,3-butadiene, chloroprene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, tropone, basil terpene (ocimene), ferrandrene, myrcene (myrcene), farnesene (farnesene), sorbic acid, sorbic acid ester, sorbate and other sorbic acids, abietic acid, etc. 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 3 carbon-carbon double bonds The conjugated triene can also be used in combination of two or more kinds of the conjugated polyene. Preferred conjugated polyenes are sorbic acids such as sorbic acid, sorbic acid ester, and sorbic acid salt.

As the lubricating agent used in the present invention, higher fatty acids, for example, higher fatty acids such as oleic acid, lauric acid, palmitic acid, myristic acid, stearic acid, behenic acid, etc.; aluminum salts of these higher fatty acids, Metal salts of higher fatty acids such as calcium salts, zinc salts, magnesium salts, 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; amide stearate, behenic acid Saturated higher fatty acid amide such as amide, unsaturated higher fatty acid amide such as oleic acid amide, erucic acid amide, vinyl bis-stearyl amide, vinyl bis-oleic acid amide, vinyl bis-erucic acid amide, The amides of higher fatty acids such as bis-higher fatty acid amides such as vinylbislaurate amides can be used alone or in combination of two or more.

The EVOH resin composition is advantageous for more efficient preparation of EVOH films formed therefrom. Appropriate methods and equipment for preparing EVOH membranes may include methods and equipment 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 force in the extruder, and can also reduce the gel generation of the film or multi-layer structure formed by the EVOH resin composition, The appearance of the film or multilayer structure formed by the EVOH resin composition is improved.

The EVOH resin composition of the present invention usually has a moisture content in a specific range. For example, taking the volatile content as the evaluation of the moisture content of the EVOH resin composition, the moisture content of the EVOH resin composition 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 to 1 wt%, between 0.08 to 1 wt%, between 0.05 to 1 wt% or between 0.01 to 0.5 wt%. It was unexpectedly 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 produce bubbles, uneven film thickness, and increased flow marks. There are 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 of the EVOH resin composition of the present invention; at least one polymer layer; and at least one adhesive layer. The polymer layer system may be selected from low density polyethylene layers, polyethylene grafted maleic anhydride layers, polypropylene layers, nylon layers, and combinations thereof. The adhesive layer may be a tie layer, such as ARKEMA OREVAC 18729 from ARKEMA Corporation. 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. Example 1

A non-limiting method of preparing EVOH particles formed from EVOH resin compositions is provided below. Six non-limiting Example EVOH resin compositions (Examples EVOH 1-6) and four Comparative Example EVOH resin compositions (Comparative Examples EVOH 1-4) were prepared according to methods similar to those disclosed below. However, the specific methods for preparing Examples EVOH 1-6 and Comparative Examples EVOH 1-4 generally differ from the methods disclosed below in one or more respects. 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 to a polymerization kettle equipped with a cooling coil. After the polymerization kettle was temporarily replaced with nitrogen, it was replaced with ethylene and pressed until the pressure of ethylene. becomes 45kg/cm ² . Under ethylene pressure, the temperature was raised to 67°C with stirring to initiate polymerization. Six hours after the start of 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, thereby obtaining a methanol solution of the ethylene-vinyl acetate copolymer.

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

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

Then, the solution of methanol, water and EVOH was pelletized by underwater pelletization. Specifically, the aforementioned solution of methanol, water, and EVOH was pumped into the feed pipe at a flow rate of 120 L/min using a pump, then fed into an input pipe with a diameter of 2.8 mm, and cut at 1500 rpm using a rotary knife to obtain Granules of EVOH. At the same time, circulating condensed water at 5°C was used to cool the EVOH pellets. Subsequently, the EVOH particles were centrifuged to separate out the EVOH particles and the separated EVOH pellets were washed with water, centrifuged again, and then the EVOH particles were immersed in a boric acid/sodium acetate solution, then dried and added with stearin calcium acid to obtain EVOH pellet final product. The final product of the EVOH round granular particles has a long side of 2.4 mm and a short side of 1.5 mm.

In the so-called centrifugation and washing steps, the speed of the first dehydrator is 3000 rpm; the water/wet particle ratio is 10 during conveying; the type of centrifugal pump for conveying is semi-open; the speed of the conveying pump is 2000 rpm ; The water/wet particle weight ratio is 20 during washing; the water flow speed is 1 m/min during washing; the rotation speed of the second dehydrator is 4000 rpm; and the drying is to a moisture content of 0.1%. Example EVOH 2 Granules

The EVOH pellets for Example EVOH 2 were prepared using a similar procedure to Example EVOH 1 pellets. However, when EVOH particles of Example EVOH 2 were prepared, the EVOH particles were immersed in boric acid/sodium acetate solution, and the wet particle size (long side) was 3.0 mm and the short side was 2.4 mm; the first spin speed of the dehydrator was 2000 rpm; the water/wet particle ratio is 20 when conveying; the type of centrifugal pump for conveying is open type; the speed of the conveying pump is 4000 rpm; the water/wet particle ratio is 10 when washing; The speed of the second dehydrator is 3000 rpm; it is dried to a moisture content of 0.01%. Example EVOH 3 Granules

EVOH granules for Example EVOH 3 were prepared using a similar procedure to Example EVOH 1 granules. However, when preparing EVOH particles of Example EVOH 3, the EVOH particles were immersed in boric acid/sodium acetate solution, and the wet particle size was 5.0 mm on the long side and 5.0 mm on the short side; the speed of the first dehydrator was 1500 rpm ; The water/wet particle ratio is 5 when conveying; the type of centrifugal pump used for conveying is open type; the speed of the conveying pump is 3000 rpm; the water/wet particle ratio is 25 when washing; The speed of the secondary dehydrator is 1000 rpm; it is dried to a moisture content of 0.3%. Example EVOH 4 Granules

EVOH granules for Example EVOH 4 were prepared using a similar procedure to Example EVOH 1 granules. However, when EVOH particles of Example EVOH 4 were prepared, the EVOH particles were immersed in boric acid/sodium acetate solution, and the wet particle size was 0.5 mm on the long side and 0.5 mm on the short side; the rotation speed of the first dehydrator was 4000 rpm ; The ratio of water/wet particles during conveying is 15; the type of centrifugal pump used for conveying is semi-open; the speed of the conveying 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

EVOH granules for Example EVOH 5 were prepared using a similar procedure to Example EVOH 1 granules. However, the ethylene content of the EVOH particles of Example EVOH 5 is 28 mole percent, and when preparing the EVOH particles of Example EVOH 5, the EVOH particles are immersed in a boric acid/sodium acetate solution, and the wet particles have a particle size of both long and short sides. 2.5 mm; the speed of the first dehydrator is 1000 rpm; the water/wet particle ratio during conveying is 5; the type of centrifugal pump used for conveying is open type; the conveying pump speed is 3000 rpm; the water/wet particle ratio during washing is 20; During washing, the water flow speed was 3.5 m/min; the speed of the second dehydrator was 3000 rpm; and the drying was performed to a moisture content of 0.04%. Example EVOH 6 Granules

Using a similar procedure to Example EVOH 1 granules, EVOH granules for Example EVOH 6 were prepared. 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 a boric acid/sodium acetate solution. 5 mm; the speed of the first dehydrator is 3000 rpm; the water/wet particle ratio during conveying is 5; the type of centrifugal pump for conveying is semi-open; the conveying pump speed is 4000 rpm; the water/wet particle ratio during washing is 15 ; The water flow speed during washing is 2.5 m/min; the speed of the second dehydrator is 3000 rpm; and the drying is to a moisture content of 0.05%. Comparative Example EVOH 1 Granule

EVOH granules for Comparative Example EVOH 1 were prepared using a similar procedure to Example EVOH 1 granules. However, when preparing EVOH granules of Comparative Example EVOH 1, the EVOH granules were immersed in boric acid/sodium acetate solution, and the size of the wet granules was 6 mm on both sides; the speed of the first dehydrator was 2000 rpm; The wet particle ratio is 1; the type of centrifugal pump used for conveying is semi-open; the conveying pump speed is 4000 rpm; the water/wet particle ratio is 5 during washing; the water flow speed during washing is 20 m/min; at 8000 rpm; dried to a moisture content of 0.07%. Comparative Example EVOH 2 Granules

EVOH granules for Comparative Example EVOH 2 were prepared using a similar procedure to Example EVOH 1 granules. However, when preparing EVOH granules of Comparative Example EVOH 2, the EVOH granules were immersed in boric acid/sodium acetate solution, and the size of the wet granules was 1 mm on both sides; the speed of the first dehydrator was 5000 rpm; The proportion of wet particles is 10; the type of centrifugal pump for conveying is closed type; the speed of the conveying pump is 7000 rpm; the water/wet particle ratio is 0.5 during washing; 3000 rpm; dry to 0.8% moisture content. Comparative Example EVOH 3 Granules

EVOH pellets for Comparative Example EVOH 3 were prepared using a similar procedure to Example EVOH 1 pellets. However, when preparing EVOH granules of Comparative Example EVOH 3, the EVOH granules were immersed in boric acid/sodium acetate solution, and the size of the wet granules was 4.5 mm on both sides; the speed of the first dehydrator was 2000 rpm; The wet particle ratio is 50; the type of centrifugal pump for conveying is open type; the speed of the conveying pump is 1000 rpm; the water/wet particle ratio is 100 during washing; the water flow speed during washing is 0.5 m/min; 1000 rpm; dry to 0.5% moisture content. Comparative Example EVOH 4 Granules

EVOH granules for Comparative Example EVOH 4 were prepared using a similar procedure to Example EVOH 1 granules. However, when preparing EVOH granules of Comparative Example EVOH 4, the EVOH granules were immersed in boric acid/sodium acetate solution, and the wet granules were both 5.1 mm long and short; The wet particle ratio is 3; the type of centrifugal pump for conveying is semi-open; the conveying pump speed is 3000 rpm; the water/wet particle ratio is 8 during washing; the water flow speed during washing is 10 m/min; at 3000 rpm; dried 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. Example EVOH 1-6 pellets and Comparative Example EVOH 1-4 pellets were fed into a single-layer T-die cast film extruder (optical control system MEV4) to prepare films. The thickness of the films formed from Example EVOH 1-6 particles and Comparative Example EVOH 1-4 particles were each 20 μm. The temperature of the extruder was set to 220°C, and the temperature of the die (ie, the T-die) was set to 230°C. The rotation frequency of the screw was 7 rpm (rotations/minutes). Example 3

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

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

Table 1 below provides a summary of some properties of Example EVOH Particles 1-6 and Comparative Examples EVOH Particles 1-4, namely Vmp, Vmc, Sp, Rz, boron content, alkali metal content, extruder mean torque and extruder Current, and gel-on-EVOH film generation for films formed from Examples EVOH 1-6 and Comparative Examples 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 Vmc core solid volume (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 Rz line maximum height (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 characteristics Solid volume of Vmp crest (μm ³ /μm ² ) 22.3 44.6 0.0005 12.1 Vmc core solid volume (μm ³ /μm ² ) 66.4 110.3 0.004 72.3 Sp maximum peak height (μm) 12 15 0.0005 8.2 Rz line maximum height (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 Example and Comparative Example was measured by the following method. First, a 0.1 g EVOH particle sample was decomposed using concentrated nitric acid and microwave to make the 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 measurement of the boron content derived from the boron compound used.

In addition, the alkali metal content in the EVOH pellets of the respective Examples and Comparative Examples was also measured. Take 2 g of the above EVOH particles into a platinum dish, add several mL of sulfuric acid, and heat with a gas burner. After confirming that the pellets are carbonized and the sulfuric acid white smoke disappears, add a few drops of sulfuric acid and reheat. Repeat this until the organic matter is gone, making it completely ashed. The container after the ashing was left to cool, and 1 mL of hydrochloric acid was added to dissolve it. The 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 pellets of the EVOH composition described above was converted from the alkali metal concentration in the solution.

In order to evaluate the particle surface roughness of Examples EVOH 1-6 and Comparative Examples EVOH 1-4, the EVOH particles were placed flat on the plate to measure the surface roughness of the particles, and the data when the inclination was greater than 0.5 were excluded from the measurement to ensure that The scanning plane is relatively horizontal (inclination=maximum height Sz of plane/side length of analysis range 129 μm). The laser microscope was a 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 center line 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, Sp are measured by ISO 25178:2012 method; Rz is measured by JIS B 0601 (2001) method.

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

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

In addition, for the calculation of the gel/size (Gel) of the films formed by the examples EVOH 1-6 and the comparative examples EVOH 1-4, after the EVOH was processed into a single-layer film, it was analyzed using the FSA-100 film quality test system The number of Gel in the monolayer film was evaluated according to the evaluation criteria. If the number of gels <100 μm is less than 450, “O” is the best; if the number of gels <100 μm is 450~1000, it is acceptable by “Δ”; if the number of gels <100 μm is acceptable If the number is more than 1000, it is not good with "X". If the number of gels of 100-200 μm is less than 50, “O” is the best; if the number of gels of 100-200 μm is 50-100, it is acceptable by “Δ”; if 100-200 μm If the number of gels is > 100, it is indicated by "X" as 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 by “Δ”; if the number of gels > 200 μm If the number is more than 20, it is indicated by "X" as bad.

Films formed by Examples EVOH 1-6 all have less than 450 gels of <100 μm, less than 100 of 100-200 μm, and less than 10 of films >200 μm, showing excellent properties.

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 frictional heat of EVOH during processing is insufficient and cannot be melted, and tiny gels will be formed after extrusion. Therefore, the surface roughness of EVOH particles needs to be controlled within a certain range to avoid gel formation.

By comparing the examples and comparative examples in Table 1, the inventors found that the variable factors of the method of controlling the washing program during EVOH particle processing, that is, the variable factors of immersing the EVOH particles in the 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 easy to collide with each other and cause friction when transported in water; ● Too high speed of dehydrator, too low ratio of water/wet particles, closed centrifugal pump during conveying, too high speed of conveying pump, too fast water flow rate, etc., will cause wet particles to collide and rub against each other in the washing process.

In Comparative Example 1, due to the large particle size, too low water/wet particle ratio during transportation, and too high the rotation speed of the second dehydrator, the wet particle has high friction and the roughness increases. In Comparative Example 2, because the particles are too small, the rotation speed of the first dehydrator is too high, the closed centrifugal pump is used, the rotation speed of the conveying pump is too high, and the ratio of water/wet material during washing is too low, resulting in high friction of wet particles and increased roughness. In Comparative Example 3, the water/wet particle ratio was too high during conveying, the rotational speed of the conveying pump was too low, the wet particle ratio was too high during washing, and the water flow rate was too low, resulting in insufficient particle friction and insufficient roughness.

According to the results tested by the present invention, as long as the EVOH surface roughness is controlled within a specific range, the torque 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 that are outside the desired ranges described herein, and the test results all have higher extruder torque output and extruder current, and the like The resulting film produced too much gel. Comparative Example EVOH 3 had Vmp, Vmc and Sp below the desired ranges described herein, and the test results had good torque output and current, but the film formed from Comparative Example EVOH 3 produced too much gel and had undesired properties.

To sum up, the EVOH resin composition of the present invention has low surface roughness, especially the surface roughness is between 0.0008 and 10 μm ³ /μm ² Vmp. In addition, the surface roughness of the EVOH resin composition of the present invention may further be Vmc ranging from 0.005 to 50 μm ³ /μm ² and/or 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 make films or multilayer structures. The inventors found that by controlling the surface roughness of the EVOH particles, the torque output during EVOH processing can be reduced, and the excessive amount of gel produced by the film formed by the EVOH can be reduced.

All ranges provided herein are intended to include each specific range within the given range and combinations of subranges between the given ranges. Furthermore, all ranges provided herein are inclusive of the endpoints of the stated range unless otherwise indicated. Thus, the range 1-5 specifically includes 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 incorporated herein by reference, and each individual publication or patent application is expressly and individually indicated to be incorporated by reference for any and all purposes. In the event of inconsistency between this document and any publication or patent application incorporated herein by reference, this document controls.

The terms "including", "having" and "comprising" as used herein have an open, non-limiting meaning. The terms "a" and "the" should be understood to encompass 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 numbers indicating amounts of ingredients and/or reaction conditions may in all cases be modified using the term "about", meaning within ±5% of the indicated number . As used herein, the terms "substantially free" or "substantially free" refer to less than about 2% of a particular characteristic. All elements or features expressly stated herein may be negatively excluded from the scope of the claim.

none.

none.

none.

none.

Claims (14)

An ethylene-vinyl alcohol copolymer resin composition, which is in the form of particles, comprising an ethylene-vinyl alcohol copolymer resin; wherein the ethylene-vinyl alcohol copolymer resin composition has a surface, and the surface has between 0.0008 to 0.0008 Solid volume (Vmp) at the peak of 10 μm ³ /μm ² . The ethylene-vinyl alcohol copolymer resin composition as described in claim 1, wherein the surface of the ethylene-vinyl alcohol copolymer resin composition has a core solid volume (Vmc) ranging from 0.005 to 50 μm ³ /μm ² . According to 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) ranging from 0.005 to 7 μm. According to the ethylene-vinyl alcohol copolymer resin composition described in item 1 of the claimed scope, the ethylene content of the ethylene-vinyl alcohol copolymer resin ranges from 20 to 48 mole percent. According to the ethylene-vinyl alcohol copolymer resin composition described in item 1 of the claimed scope, the saponification degree of the ethylene-vinyl alcohol copolymer resin is greater than 99.5 mole percent. According to the ethylene-vinyl alcohol copolymer resin composition described in any one of claims 1 to 5, the maximum height (Rz) of the line on the surface is 0.01-13 μm. According to the ethylene-vinyl alcohol copolymer resin composition described in item 6 of the patent application scope, the maximum height (Rz) of the line on the surface is between 0.01 and 9.9 μm. The ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 5 of the claimed scope has a water content of less than 1 weight percent. The ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 5 of the patent application scope, which has a boron content of 5-550 ppm. The ethylene-vinyl alcohol copolymer resin composition as described in any one of claims 1 to 5 of the patent application scope has an alkali metal content of 5-550 ppm. The ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 5, further comprising one of the group consisting of cinnamic acid, conjugated polyene, slip agent and alkaline earth metal, or its combination. An ethylene-vinyl alcohol copolymer film, which is formed from the ethylene-vinyl alcohol copolymer resin composition as described in any one of the patent application scopes 1 to 11. A multilayer structure comprising: (a) at least one layer formed from the ethylene-vinyl alcohol copolymer resin composition of any one of claims 1 to 11; (b) at least one polymer layer; and (c) at least one layer adhesive layer. The multilayer structure of claim 13, 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 group, and the adhesive layer is a tie layer.