Ethylene-vinyl alcohol copolymer composition, single-layer film and multilayer structure containing the same

Abstract

The present invention relates to an ethylene-vinyl alcohol copolymer composition, a single-layer film, and a multilayer structure containing the same. The ethylene-vinyl alcohol copolymer composition comprises an ethylene-vinyl alcohol copolymer, an antioxidant, and a fluorine-containing compound; the ratio of the antioxidant content to the fluorine content is 0.5 to 65. Consequently, films containing the ethylene-vinyl alcohol copolymer composition not only exhibit excellent heat resistance but also avoid the formation of large amounts of gel particles during the preparation process.

Description

Technical Field

[0001] The present invention generally relates to an ethylene-vinyl alcohol (EVOH) copolymer composition, but is not limited thereto; more particularly, the present invention relates to an EVOH copolymer composition, a single-layer film, and a multilayer structure comprising the same. Background Art

[0002] Ethylene-vinyl alcohol (EVOH) copolymer compositions possess excellent transparency, gas barrier properties, solvent / oil resistance, and mechanical strength. They are widely used in laminates for preserving perishable goods. For example, EVOH copolymer compositions and laminates are commonly used in the food packaging, medical device and consumables, pharmaceutical, electronics, and agricultural chemical industries. Specifically, EVOH compositions are often incorporated into laminates to form a distinct layer that acts as an oxygen barrier.

[0003] The preparation process of ethylene-vinyl alcohol copolymer often involves high temperatures. Because its molecules contain many reactive groups, high-temperature processing can easily cause material stability changes. Specifically, this can lead to carbon deposits on the die used in the preparation process, gel formation in the sample, and even degradation of the finished product. Therefore, heat resistance is a crucial property in the preparation of ethylene-vinyl alcohol copolymer.

[0004] In current technology, various types of heat stabilizers or additives are usually added, such as adding a specific amount of antioxidants to the material, to solve the above problem. Summary of the Invention

[0005] This summary is intended to provide a simplified summary of the present invention so that readers can have a basic understanding of the present invention. This summary is not a complete overview of the present invention and is not intended to identify important or critical components of the embodiments of the present invention or to delineate the scope of the present invention.

[0006] The inventors of this application discovered that, based on the background art, while adding specific oxidants to ethylene-vinyl alcohol copolymer materials effectively improves their heat resistance, it also causes the formation of a large number of gel particles (also known as fisheyes) in the ethylene-vinyl alcohol copolymer materials, resulting in poor processing performance. To address this issue, the inventors of this application conducted further experiments and discovered that when a specific antioxidant and a fluorine-containing compound are added simultaneously, the fluorine-containing compound prevents the material from sticking to the hot metal and enhances the mixing effect of the ethylene-vinyl alcohol copolymer and the antioxidant, thereby resolving the aforementioned problem of large amounts of gel particles generated by the addition of antioxidants to the ethylene-vinyl alcohol copolymer materials.

[0007] Specifically, one aspect of the present invention provides an ethylene-vinyl alcohol copolymer composition, which includes an ethylene-vinyl alcohol copolymer, an antioxidant and a fluorine-containing compound; wherein the ratio of the antioxidant content to the fluorine content in the ethylene-vinyl alcohol copolymer composition is 0.5 to 65.

[0008] According to one embodiment of the present invention, the content of the antioxidant is 250 ppm to 3200 ppm.

[0009] According to one embodiment of the present invention, the antioxidant is selected from the group consisting of hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants, benzotriazole antioxidants, and diphenyl ketone antioxidants.

[0010] According to one embodiment of the present invention, the fluorine content of the ethylene-vinyl alcohol copolymer composition is 40 ppm to 700 ppm.

[0011] According to one embodiment of the present invention, the fluorine-containing compound is a compound derived from one or a combination of compounds selected from the group consisting of vinylidenefluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE).

[0012] According to one embodiment of the present invention, the ethylene-vinyl alcohol copolymer composition contains a boron content ranging from 10 to 450 ppm.

[0013] According to one embodiment of the present invention, the ethylene-vinyl alcohol copolymer composition contains an alkali metal content ranging from 10 to 450 ppm.

[0014] According to one embodiment of the present invention, the fluorine-containing compound is in the form of particles, and the size thereof is no greater than 20 microns.

[0015] Another aspect of the present invention provides a single-layer film comprising the ethylene-vinyl alcohol copolymer composition as described above, which has a 2 There are less than 200 gel particles with a particle size of less than 100 μm in the area.

[0016] According to one embodiment of the present invention, the ethylene-vinyl alcohol copolymer composition included in the single-layer film has an ethylene content of 20 to 35 mole %, and can withstand heat at 150° C. for greater than or equal to 110 hours.

[0017] According to one embodiment of the present invention, the ethylene-vinyl alcohol copolymer composition contained in the single-layer film has an ethylene content of 36 to 50 mole %, and can withstand heat at 150° C. for more than or equal to 80 hours.

[0018] Another aspect of the present invention provides a multilayer structure comprising at least one layer formed from the ethylene-vinyl alcohol copolymer composition described above; the multilayer structure further comprises at least one polymer layer and at least one adhesive layer.

[0019] According to one embodiment of the present invention, the polymer layer is selected from the group consisting of a polyethylene layer, a polyethylene grafted maleic anhydride layer, a polypropylene layer, a nylon layer, and combinations thereof.

[0020] The advantage of the present invention is that by adding the antioxidant and the fluorine-containing polymer together and in a specific content ratio, the ethylene-vinyl alcohol copolymer composition provided by the present invention not only has excellent heat resistance, but also can avoid the generation of a large number of gel particles during the preparation process. DETAILED DESCRIPTION

[0021] In order to make the description of the present invention more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present invention, but this is not the only form of implementing or using the specific embodiments of the present invention. In this specification and the appended claims, unless the context otherwise indicates, "a", "an" and "the" may also be interpreted as plural. In addition, in this specification and the appended claims, unless otherwise indicated, "being provided on something" may be regarded as directly or indirectly contacting the surface of something by attachment or other forms, and the definition of the surface should be determined based on the context / paragraph meaning of the content of the specification and the common knowledge in the field to which the description belongs.

[0022] Although the numerical ranges and parameters used to define the present invention are approximate, the numerical values ​​of the specific embodiments have been presented herein as precisely as possible. However, any numerical value inherently and inevitably contains standard deviations resulting from individual testing methods. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range. Alternatively, the term "about" means that the actual value falls within an acceptable standard error of the mean, as determined by one of ordinary skill in the art. Therefore, unless otherwise indicated, the numerical parameters disclosed in this specification and the appended claims are approximate and may be modified as needed. At a minimum, these numerical parameters should be understood to include the number of significant digits indicated and to apply normal rounding.

[0023] The present invention relates to an ethylene-vinyl alcohol copolymer (EVOH) composition. The EVOH composition contains both an antioxidant and a fluorine-containing compound, with the ratio of the antioxidant content to the fluorine content being within a specific range. The EVOH composition can be used to prepare single-layer films or multilayer structures.

[0024] In one aspect, the present invention provides an ethylene-vinyl alcohol copolymer composition comprising an ethylene-vinyl alcohol copolymer, an antioxidant, and a fluorine-containing compound. The ratio of the antioxidant content to the fluorine content in the ethylene-vinyl alcohol copolymer composition is 0.5 to 65, for example, 0.52, 0.53, 4.25, 4.80, 4.87, 5.13, 5.50, 7.58, 8.57, 8.64, 9.86, 10.21, 10.47, 10.67, 27.23, 50.28, or 63.50.

[0025] As used herein, the "antioxidant" is a compound used to capture free radicals generated by degradation of ethylene-vinyl alcohol copolymer. According to at least one embodiment of the present invention, the antioxidant is selected from the group consisting of hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants, benzotriazole antioxidants, and diphenyl ketone antioxidants. In a preferred embodiment, the antioxidant is present in an amount of 250 ppm to 3200 ppm relative to the ethylene-vinyl alcohol copolymer composition, for example, but not limited to, 250 ppm, 500 ppm, 750 ppm, 1000 ppm, 1250 ppm, 1500 ppm, 1750 ppm, 2000 ppm, 2250 ppm, 2500 ppm, 2750 ppm, 3000 ppm, 3200 ppm, or a range between any two of the foregoing values. The ethylene-vinyl alcohol copolymer composition of the present invention includes an antioxidant, which can capture free radicals generated by the ethylene-vinyl alcohol copolymer during heating and reduce the degradation of the ethylene-vinyl alcohol copolymer.

[0026] As used herein, the fluorine-containing compound may also be referred to as a fluoropolymer. According to at least one embodiment of the present invention, the fluorine-containing compound may include or be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (polytetrafluoroethylene), polyhexafluoropropylene (polyhexafluoropropylene), polychlorotrifluoroethylene (PCTFE), 2-chloropentafluoropropene (2-chloropentafluoropropene), dichlorodifluoroethylene (dichlorodifluoroethylene), 1,1-dichlorofluoroethylene (1,1-dichlorofluoroethylene), and combinations thereof. Additionally or alternatively, the fluorine-containing compound is derived from a copolymer of at least two selected from vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). In some embodiments, the fluorine-containing polymer may include a copolymer derived from two or more of VDF, HFP, and TFE. For example, the fluoropolymer may include a copolymer derived from VDF and HFP, a copolymer derived from TFE and HFP, a copolymer derived from VDF and TFE, and / or a copolymer derived from VDF, HFP, and TFE.

[0027] The fluorine content of the ethylene-vinyl alcohol copolymer composition is 40 ppm to 700 ppm relative to the ethylene-vinyl alcohol copolymer composition; according to some embodiments of the present invention, the fluorine content may be between 40 and 100 ppm; between 101 and 200 ppm; between 201 and 300 ppm; between 301 and 400 ppm; between 401 and 500 ppm; between 501 and 600 ppm; or between 601 and 700 ppm. According to at least one embodiment of the present invention, the fluorine-containing compound is in the form of particles. Preferably, the particle form may be microparticles; according to the International Union of Pure and Applied Chemistry (IUPAC) definition of microparticles as 10 -7 to 10 -4In the present invention, the particle size is expressed in terms of diameter or the length of the major axis across the cross-sectional area. The size of the fluorochemical compound can be controlled by regulating the type or species of fluoropolymer, the amount of fluoropolymer and the ethylene content of the ethylene-vinyl alcohol copolymer composition. If the fluorochemical compound particle is spherical, the diameter of its cross section determines whether the fluorochemical compound particle has the desired particle size. In the case where the fluorochemical compound particle is not spherical and / or the cross-sectional shape of the fluorochemical compound particle is not circular (e.g., elliptical or lumpy), the major axis length of the cross section of the fluorochemical compound particle determines whether the fluorochemical compound particle has the desired particle size. The major axis is defined as the axis with the maximum length. In some embodiments, the sizes of all the fluorochemical compound particles evaluated on the cross section of the EVOH resin composition 100 are not greater than 20 μm, for example, not greater than 19 μm, not greater than 18 μm, not greater than 16 μm, not greater than 14 μm or not greater than 12 μm. An appropriate amount of fluorine-containing compound particles can reduce the generation of carbon residue in the die during the heating process of the ethylene-vinyl alcohol copolymer composition of the present invention, and can also reduce the number of gels when the ethylene-vinyl alcohol copolymer composition is extruded, thereby making the product preparation process smoother and the quality better.

[0028] Prior art often enhances the heat resistance of ethylene-vinyl alcohol copolymers by adding antioxidants. However, the inventors of this invention discovered that adding more antioxidants to improve heat resistance can cause aggregation and gelation. The present invention, by adding a fluorinated compound, allows the ethylene-vinyl alcohol copolymer composition to be heated stably during processing. The presence of the antioxidant enhances heat resistance and reduces gelation. In other words, the presence of the fluorinated compound enhances the performance of the antioxidant, and the combined presence of the fluorinated compound and antioxidant also enhances the processing performance of the ethylene-vinyl alcohol copolymer composition.

[0029] On the other hand, the inventors discovered that when the ethylene-vinyl alcohol copolymer composition includes an ethylene-vinyl alcohol copolymer, an antioxidant, and a fluorine-containing compound, the fluorine-containing compound can prevent the ethylene-vinyl alcohol copolymer composition from adhering to hot metal in machinery, achieving external effects related to physical properties. Furthermore, the ethylene-vinyl alcohol copolymer can be further mixed with the antioxidant, thereby enhancing the antioxidant's effectiveness and achieving internal effects related to chemical reactions. Therefore, the ethylene-vinyl alcohol copolymer composition of the present invention achieves a superior internal and external addition effect compared to the effects of adding only one of the compounds.

[0030] According to some embodiments of the present invention, the ethylene-vinyl alcohol copolymer composition further includes a boron compound, and the content thereof is between 10 and 450 ppm. Specifically, the boron content can be 10 to 450 ppm, 10 to about 400 ppm, 10 to about 350 ppm, 10 to about 300 ppm, 10 to about 275 ppm, 10 to about 250 ppm, 10 to about 225 ppm, 10 to about 200 ppm, 10 to about 175 ppm, about 20 to 450 ppm, about 20 to about 400 ppm, about 20 to about 350 ppm, about 20 to about 30 ... about 275 ppm, about 20 to about 250 ppm, about 20 to about 225 ppm, about 20 to about 200 ppm, about 20 to about 175 ppm, about 60 to 450 ppm, about 60 to about 400 ppm, about 60 to about 350 ppm, about 60 to about 300 ppm, about 60 to about 275 ppm, about 60 to about 250 ppm, about 60 to about 225 ppm, about 60 to about 200 ppm, about 60 to about 175 ppm, about 100 to 450 ppm, about 100 to about 400 ppm, about 100 to about 350 ppm, about 100 to about 300 ppm, about 100 to about 275 ppm, about 100 to about 250 ppm, about 100 to about 225 ppm, about 100 to about 200 ppm, about 100 to about 175 ppm, about 140 to 450 ppm, about 140 to about 400 ppm, about 140 to about 350 ppm, about 140 to about 300 ppm, about 140 to about 275 ppm, about 140 to about 250 ppm, about 1 The boron content of the ethylene-vinyl alcohol copolymer composition is preferably from about 40 to about 225 ppm, from about 140 to about 200 ppm, from about 180 to about 450 ppm, from about 180 to about 400 ppm, from about 180 to about 350 ppm, from about 180 to about 300 ppm, from about 180 to about 275 ppm, from about 180 to about 250 ppm, from about 180 to about 225 ppm, from about 220 to 450 ppm, from about 220 to about 400 ppm, from about 220 to about 350 ppm, from about 220 to about 300 ppm, and from about 220 to about 275 ppm. When the boron content of the ethylene-vinyl alcohol copolymer composition is within a certain range, its viscosity can be increased, the chance of adhesion to the screw can be reduced, and the material can have a self-cleaning function, thereby further improving the uniformity of film thickness.

[0031] 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), potassium aluminum borate, ammonium borate (e.g., ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate), cadmium borate (e.g., cadmium orthoborate, cadmium tetraborate), potassium borate (e.g., potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate), silver borate (e.g., silver metaborate, silver tetraborate), copper borate (e.g., copper (II) borate, copper metaborate, copper tetraborate), sodium borate (e.g., sodium metaborate, sodium diborate, tetraborate), and the like.

[0014] Examples of the present invention include sodium borate, sodium pentaborate, sodium hexaborate, sodium octaborate), lead borate (e.g., lead metaborate, lead hexaborate), nickel borate (e.g., nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate), barium borate (e.g., barium orthoborate, barium metaborate, barium diborate, barium tetraborate), bismuth borate, magnesium borate (e.g., magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate), manganese borate (e.g., manganese (I) borate, manganese metaborate, manganese tetraborate), lithium borate (e.g., lithium metaborate, lithium tetraborate, lithium pentaborate), salts thereof, or combinations thereof. Borate minerals such as borax, kainite, breccia, szaibelyte, suanite, and szaibelyte may be included. 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.

[0032] In some cases, in addition to a boron content of 10 to 450 ppm, the ethylene-vinyl alcohol copolymer composition may also contain cinnamic acid, alkali metals, conjugated polyenes, lubricants, alkaline earth metals, salts thereof and / or mixtures thereof. The above substances can be used to give the ethylene-vinyl alcohol copolymer composition better properties. According to some embodiments of the present invention, if the content of the conjugated polyene structure compound per unit weight of the ethylene-vinyl alcohol copolymer composition is 1 to 30,000 ppm, the coloring after heating can be further suppressed, making the thermal stability more excellent. If the content of the alkali metal compound or alkaline earth metal compound per unit weight of the ethylene-vinyl alcohol copolymer composition is 1 to 1000 ppm in terms of metal, preferably 10 to 450 ppm, the long-term operation formability can be made more excellent. In addition, if the lubricant content per unit weight of the ethylene-vinyl alcohol copolymer composition is 1 to 300 ppm, the processability can be made more excellent. According to at least one preferred embodiment, the ethylene vinyl alcohol copolymer resin composition has an alkali metal content between 10 and 450 ppm, for example but not limited to: 10 ppm, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or between any two of the foregoing values.

[0033] On the other hand, the present invention further provides a single-layer film comprising the ethylene-vinyl alcohol copolymer composition as described above, wherein the single-layer film has a thickness of 1 m 2 The number of gel particles with a diameter of less than 100 μm within the area is less than 200. Specifically, the number of gel particles is determined by using a charged coupled device (CCD) sensor and an FSA-100 designed with FSA-100 V.8 software for analysis.

[0034] According to at least one embodiment of the present invention, the thickness of the monolayer film is 50 to 150 μm, preferably 100 μm. Furthermore, the ethylene-vinyl alcohol copolymer contained in the monolayer film has an ethylene content. For example, the ethylene content may be from about 20 to about 50 mole%, from about 25 to about 45 mole%, from about 28 to about 42 mole%, or from about 30 to about 40 mole%. The ethylene-vinyl alcohol copolymer composition may also be formed from two or more ethylene-vinyl alcohol copolymers having different ethylene contents. For example, the ethylene content of one of the ethylene-vinyl alcohol copolymers may be in the range of from about 20 to about 35 mole%, such as from about 24 to about 35 mole%, from about 28 to about 35 mole%, from about 20 to about 32 mole%, from about 24 to about 32 mole%, from about 28 to about 32 mole%, from about 20 to about 30 mole%, or from about 24 to about 30 mole%. Furthermore, the ethylene-vinyl alcohol copolymer composition can withstand heat at 150°C for at least 110 hours. Additionally or alternatively, according to some embodiments of the present invention, the ethylene content of the ethylene-vinyl alcohol copolymer may be in the range of about 36 to about 50 mole%, for example, about 40 to about 50 mole%, about 44 to about 50 mole%, about 36 to about 45 mole%, or about 40 to about 45 mole%. Furthermore, the ethylene-vinyl alcohol copolymer composition may be heat-resistant at a temperature of 150° C. for greater than or equal to 80 hours.

[0035] In addition, the present invention further provides a multilayer structure comprising at least one layer formed from the ethylene-vinyl alcohol copolymer composition of the present invention; at least one polymer layer; and at least one adhesive layer. The polymer layer can be selected from a polyethylene layer, a polyethylene grafted maleic anhydride layer, a polypropylene layer, a nylon layer, and combinations thereof. The adhesive layer can be a tie layer, such as ARKEMA OREVAC 18729 from ARKEMA.

[0036] Example

[0037] The following non-limiting examples of various aspects of the present invention are provided primarily to illustrate various aspects of the present invention and the benefits achieved thereby.

[0038] Preparation of ethylene-vinyl alcohol copolymer

[0039] According to at least one embodiment of the present invention, ethylene-vinyl alcohol copolymer is prepared by saponifying ethylene-vinyl acetate copolymer (EVAC) with an ethylene content of 29 or 44 mole percent to a saponification degree of 99.5% to produce the ethylene-vinyl alcohol copolymer. Subsequently, the ethylene-vinyl alcohol copolymer is dissolved in a solution containing methanol and water (in a ratio of 70:30). The solution then has an ethylene-vinyl alcohol copolymer solids content of 41 wt.%, and the solution is then heated to 60°C.

[0040] Next, the solution of methanol, water, and ethylene-vinyl alcohol copolymer was pelletized using underwater pelletization. Specifically, the solution of methanol, water, and ethylene-vinyl alcohol copolymer was pumped into a feed pipe at a flow rate of 120 L / min using a pump, then fed into an inlet pipe with a diameter of 2.8 mm, where it was cut using a rotary blade at 1500 rpm. Water at 5°C was added to cool the ethylene-vinyl alcohol copolymer pellets. The ethylene-vinyl alcohol copolymer pellets were then centrifuged to separate the ethylene-vinyl alcohol copolymer particles. The separated ethylene-vinyl alcohol copolymer particles were washed with water and then dried to obtain the ethylene-vinyl alcohol copolymer pellets.

[0041] Preparation of fluorinated compound A

[0042] An autoclave was used as a batch reactor to prepare Example fluorine-containing compound A. The autoclave had an internal volume of about 20 L and was equipped with an electromagnetic induction stirrer. The autoclave was fully filled with nitrogen (N2) and then filled with reduced-pressure nitrogen five times.

[0043] While reducing the pressure in the autoclave, 6,960 g of deoxygenated pure water, 3,204 g of 1,1,2-trichloro-1,2,2-trifluoroethane, and 3.5 g of methylcellulose were placed in the autoclave. The methylcellulose, with a viscosity of 50 cp, was stirred into the composition at 450 rpm as a suspension stabilizer. The composition in the autoclave was then maintained at 52°C.

[0044] A monomer consisting of 25.3 wt% vinylidene fluoride (VDF), 68.6 wt% hexafluoropropylene (HFP) and 6.1 wt% tetrafluoroethylene (TFE) was mixed into the batch as the filling gas and filled to 10 kg / cm 2. Subsequently, 45.6 g of a solution containing about 90 wt % of 1,1,2-trichloro-1,2,2-trifluoroethane and 10 wt % of diisopropyl peroxydicarbonate was added as a catalyst to initiate the polymerization reaction. Diisopropyl peroxydicarbonate is used as an initiator to initiate the polymerization reaction. Since the pressure decreases during the polymerization reaction, a mixed monomer containing 44.7 wt % of VDF, 32.5 wt % of HFP and 22.8 wt % of TFE was added to increase the pressure to 10 kg / cm 2 After the polymerization reaction was completed, the remaining mixed monomers were removed, and the resulting suspension was dehydrated using a centrifuge, washed with deionized water, and then vacuum-dried at 100° C. to obtain about 7.5 kg of Example fluorine-containing compound A.

[0045] Preparation of fluorinated compound B

[0046] A similar autoclave was used to prepare Example Fluoro Compound B and was set up in the same manner as for the preparation of Example Fluoro Compound A. The autoclave was also refilled with reduced pressure nitrogen five times.

[0047] While reducing the pressure in the autoclave, 7,200 g of deoxygenated pure water, 3,250 g of 1,1,2-trichloro-1,2,2-trifluoroethane, and 4 g of methylcellulose were placed in the autoclave. The methylcellulose, with a viscosity of 50 cp, was stirred into the batch at 500 rpm as a suspension stabilizer. The batch in the autoclave was then maintained at 52°C.

[0048] A monomer consisting of 25 wt% VDF, 55 wt% HFP and 20 wt% TFE was used as the filling gas and filled to 20 kg / cm 2 Subsequently, 40 g of a solution containing about 85 wt% of 1,1,2-trichloro-1,2,2-trifluoroethane and 15 wt% of diisopropyl peroxydicarbonate was added as a catalyst to initiate the polymerization reaction. Diisopropyl peroxydicarbonate is used as an initiator to initiate the polymerization reaction. Since the pressure decreases during the polymerization reaction, a mixed monomer containing 40 wt% of VDF, 35 wt% of HFP and 25 wt% of TFE was added to increase the pressure to 20 kg / cm 2 After the polymerization reaction was completed, the remaining mixed monomers were removed, and the resulting suspension was dehydrated using a centrifuge, washed with deionized water, and then vacuum-dried at 100° C. to obtain about 6 kg of the fluorinated compound B of Example.

[0049] Preparation of ethylene-vinyl alcohol copolymer compositions

[0050] The ethylene-vinyl alcohol copolymer composition of the present invention is prepared by using the aforementioned essential ingredients of the ethylene-vinyl alcohol copolymer, the fluorinated compound, and the antioxidant, and optionally blending the aforementioned optional additional ingredients. The preparation method can include known methods such as dry blending, melt mixing, solution mixing, and impregnation, and any combination of these methods can also be used.

[0051] According to some embodiments of the present invention, the ethylene-vinyl alcohol copolymer particles, the antioxidant, and the fluorine-containing compound can be directly prepared into ethylene-vinyl alcohol copolymer composition particles by dry blending using a dry mixer or other methods, or by melt mixing.

[0052] According to other embodiments of the present invention, the ethylene-vinyl alcohol copolymer particles can be mixed with a fluorine-containing compound or the antioxidant to form two masterbatches; then, the two masterbatches are prepared into ethylene-vinyl alcohol copolymer composition particles by dry mixing or other methods.

[0053] Preparation of single-layer films

[0054] According to some embodiments of the present invention, the ethylene-vinyl alcohol copolymer composition particles prepared above were further fed into a single-layer T-die film casting extruder (optical control system MEV4) to produce a film. Specifically, the extruder temperature was set at 220°C; the die (i.e., T-die) temperature was set at 230°C; and the screw rotation frequency was 7 rpm (rotations / minutes).

[0055] Analysis and evaluation methods

[0056] Antioxidant content analysis

[0057] According to some embodiments of the present invention, the analysis method involves first uniformly pulverizing 200 g of the finished particles. Then, extracting a 5 g powder sample with 10 ml of an organic solvent (e.g., toluene, dichlorotoluene, acetone, etc.) that is soluble in antioxidants is performed. The extract is diluted and analyzed by LC-Q-TOF. Furthermore, a calibration curve is generated using standard solutions of the antioxidants, and the absolute calibration curve method can be used to quantify the antioxidant content.

[0058] Total fluorine content analysis

[0059] Here, total fluoride content was analyzed using an ion chromatography (IC) instrument: Metrohm 930 Compact ICFlex / Ses / PP / Deg. Test method: NIEA W415.54B (Test method for anions in water). Pretreatment: 20g of sample was combusted in an oxygen bomb, extracted with water, and then analyzed. Samples were randomly sampled 10 times, and the average of these 10 tests was used.

[0060] Gel particle analysis and evaluation

[0061] After the ethylene-vinyl alcohol copolymer composition was made into a film, the gel particles were measured and analyzed using a charged coupled device (CCD) sensor and FSA-100 designed with FSA-100 V.8 software; specifically, if the gel particles were measured at 1 m 2 The number of gel particles with a size of less than 100 μm is less than 200, which is represented by "O"; if the number of gel particles with a size of less than 100 μm is less than 200, it is represented by "O". 2 If the number of gel particles with a size of less than 100 μm is greater than 200, it is represented by "X".

[0062] Heat resistance analysis and evaluation

[0063] After forming the ethylene-vinyl alcohol copolymer composition into a 100μm thick film, the aging characteristics were measured at a standard test temperature of 150°C using DIN EN ISO 2578:1998-10. The tensile test method was ASTM D882. Specifically, for ethylene-vinyl alcohol copolymers with an ethylene content of 20-35 mol%, a heat resistance rating of "0" was given if the film lasted longer than 110 hours; otherwise, it was given an "X." For ethylene-vinyl alcohol copolymers with an ethylene content of 36-50 mol%, a heat resistance rating of "0" was given if the film lasted longer than 80 hours; otherwise, it was given an "X."

[0064] Examples 1 to 17

[0065] Here, the present invention adopts the same or similar preparation method to prepare the ethylene-vinyl alcohol copolymer compositions of Examples 1 to 17; please refer to Table 1-1 and Table 1-2 for detailed variables or preparation parameters.

[0066] Table 1-1.

[0067]

[0068]

[0069] Table 1-2.

[0070]

[0071]

[0072] Specifically, in Examples 1 to 17, the method of Example 1 directly melt-mixed ethylene-vinyl alcohol copolymer particles with an antioxidant and a fluorine-containing compound to produce ethylene-vinyl alcohol copolymer composition particles. Specifically, the method of Example 1 mixed the ethylene-vinyl alcohol copolymer particles with the antioxidant and the fluorine-containing compound using a Zenix ZPT-32HT twin-screw extruder (available from Zeki Industrial Co., Ltd.) with an aspect ratio of 20:1 (20 mm / mm), a twin-screw speed of 100 rpm, and a hopper speed of 15 rpm.

[0073] The preparation method of Examples 2 to 17 is to add the antioxidant to the ethylene-vinyl alcohol copolymer pellets in step 1 to form a masterbatch MB-A, and to add the fluorinated compound to the ethylene-vinyl alcohol copolymer pellets to form a masterbatch MB-B. Then, in step 2, the two masterbatches (MB-A and MB-B) are dry-blended to form ethylene-vinyl alcohol copolymer composition particles. Specifically, Examples 2 to 17 use the same extruder as Example 1, also with an aspect ratio of 20:1 (20 mm / mm) and a twin-screw speed of 10 rpm. EVOH is mixed with the antioxidant and the fluorinated compound to prepare MB-A and MB-B, respectively. EVOH is then mixed with the prepared MB-A and MB-B in a dry blender at 30 rpm for 30 minutes.

[0074] In addition, it should be noted that the content parameters in Tables 1-1 and 1-2 represent parts by weight, and the units used are all weight percentages (%); EV29 represents an ethylene-vinyl alcohol copolymer composition with an ethylene content of 29 mole%, and EV44 represents an ethylene-vinyl alcohol copolymer composition with an ethylene content of 44 mole%. The antioxidants used here are hindered phenol type (trade code: IRGANOX 1010; Antioxidant CA; IRGANOX 1098), hindered amine type (trade code: 445), phosphite type (trade code: IRGANOX 168), thioester type (trade code: 412S); the fluorine-containing compounds are the fluorine-containing compounds A and B as described above.

[0075] Comparative Examples 1 to 15

[0076] Here, the present invention adopts the same or similar preparation method to prepare the ethylene-vinyl alcohol copolymer compositions of Comparative Examples 1 to 15; please refer to Table 2-1 and Table 2-2 for detailed variables or preparation parameters.

[0077] Table 2-1.

[0078]

[0079] Table 2-2

[0080]

[0081] Specifically, in Comparative Examples 1 to 15, no antioxidant or fluorine-containing compound was added to Comparative Examples 1 to 2; the preparation method of Comparative Example 3 was similar to that of Example 1, in which ethylene-vinyl alcohol copolymer particles and an antioxidant were directly melt-mixed to prepare ethylene-vinyl alcohol copolymer composition particles; and the preparation methods of Comparative Examples 4 to 15 were similar to those of Examples 2 to 17, in which the antioxidant or the fluorine-containing compound was added to the ethylene-vinyl alcohol copolymer particles in step 1 to form two masterbatches (MB-A and MB-B, respectively), and in step 2, the two masterbatches were dry-mixed to prepare ethylene-vinyl alcohol copolymer composition particles (wherein the masterbatch in Comparative Example 6 contained only MB-A, and the masterbatch in Comparative Example 15 contained only MB-B).

[0082] In addition, it should be noted that the content parameters in Tables 2-1 and 2-2 represent parts by weight, and the units used are all weight percentages (%); EV29 represents an ethylene-vinyl alcohol copolymer composition with an ethylene content of 29 mole%, and EV44 represents an ethylene-vinyl alcohol copolymer composition with an ethylene content of 44 mole%; antioxidants can be divided into hindered phenol type (trade code: IRGANOX 1010; Antioxidant CA; IRGANOX 1098) and phosphite type (trade code: IRGANOX 168); fluorine-containing compounds are the fluorine-containing compounds A and B described above, respectively.

[0083] Analysis and evaluation results

[0084] The present invention further analyzed the antioxidant content, total fluorine concentration, and the ratio of the antioxidant content and total fluorine concentration in Examples 1 to 17 and Comparative Examples 1 to 15. Furthermore, the monolayer films prepared from the ethylene-vinyl alcohol copolymer compositions of Examples 1 to 17 and Comparative Examples 1 to 15 were analyzed and evaluated for gel particle formation and heat resistance. "NA" indicates a zero content or a value too low to be detected. Detailed results are shown in Tables 3-1 and 3-2, respectively.

[0085] Table 3-1.

[0086]

[0087] Table 3-2.

[0088]

[0089] By comparison, it can be seen that when the antioxidant-to-fluorine content ratio of the ethylene-vinyl alcohol copolymer composition is 0.5 to 65 (as in Examples 1 to 17), the resulting films not only exhibit ideal heat resistance but also avoid the formation of large amounts of gel particles during the preparation process. In contrast, Comparative Examples 1 to 2, which do not include any antioxidant or fluorine-containing polymer, exhibit unsatisfactory heat resistance. Comparative Examples 3 and 6, which contain only antioxidants, exhibit only good heat resistance in terms of film properties, but poor gel particle formation. Comparative Example 15, which contains only fluorine-containing polymer, exhibits poor heat resistance and poor gel particle formation. Furthermore, despite the addition of both antioxidants and fluorine-containing polymers, the remaining comparative examples fail to achieve both ideal heat resistance and the avoidance of large amounts of gel particles.

[0090] In view of this, the present invention controls the ratio of antioxidant to fluorine content in the ethylene-vinyl alcohol copolymer composition, thereby making the ethylene-vinyl alcohol copolymer composition and the film containing the same not only have excellent heat resistance, but also avoid the generation of a large number of gel particles during the preparation process.

[0091] The present invention has been described in detail above. However, what has been described above is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. In other words, all equivalent changes and modifications made within the scope of the patent application of the present invention should still fall within the scope of the patent application of the present invention.

Claims

1. An ethylene-vinyl alcohol copolymer composition comprising an ethylene-vinyl alcohol copolymer, an antioxidant and a fluorine-containing compound; wherein: The ratio of the antioxidant content to the fluorine content in the ethylene-vinyl alcohol copolymer composition is 0.5 to 65, the content of the antioxidant is 250 ppm to 3200 ppm, and the fluorine content of the ethylene-vinyl alcohol copolymer composition is 40 ppm to 700 ppm.

2. The ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the antioxidant is selected from the group consisting of hindered phenol antioxidants, hindered amine oxidants, phosphite antioxidants, thioester antioxidants, benzotriazole antioxidants, and diphenyl ketone antioxidants.

3. The ethylene-vinyl alcohol copolymer composition of claim 1 , wherein the fluorine-containing compound is a compound derived from one or a combination of compounds selected from the group consisting of vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE).

4. The ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3, having a boron content of 10 to 450 ppm.

5. The ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3, having an alkali metal content of 10 to 450 ppm.

6. The ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3, wherein the fluorine-containing compound is in the form of particles with a size of no greater than 20 microns.

7. A single-layer film comprising the ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the single-layer film has less than 200 gel particles with a particle size of 100 μm or less per an area of ​​1 m².

8. The monolayer film according to claim 7, wherein the ethylene-vinyl alcohol copolymer composition has an ethylene content of 20 to 35 mole %, and has a heat resistance time of greater than or equal to 110 hours at 150°C.

9. The single-layer film according to claim 7, wherein the ethylene-vinyl alcohol copolymer composition has an ethylene content of 36 to 50 mole%, and is heat-resistant at 150° C. for 80 hours or longer.

10. A multilayer structure comprising: at least one layer formed from the ethylene-vinyl alcohol copolymer composition of claim 1; at least one polymer layer; as well as At least one adhesive layer.

11. The multilayer structure of claim 10, wherein the polymer layer is selected from the group consisting of a polyethylene layer, a polyethylene grafted maleic anhydride layer, a polypropylene layer, a nylon layer, and combinations thereof.

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