A modified evo h resin composition and a method for producing the same

Abstract

This invention discloses a modified EVOH resin composition and its preparation method. The preparation method of the modified EVOH resin composition includes the following steps: (1) uniformly spraying 0.05-0.2 parts of epoxytrimethoxysilane onto the surface of 3-8 parts of flake-shaped hexagonal boron nitride, and naturally air-drying to obtain modified flake-shaped hexagonal boron nitride; (2) uniformly mixing the modified flake-shaped hexagonal boron nitride from step (1) with 90-100 parts of EVOH resin and 0.1-2 parts of antioxidant, adding the mixture from the feed port of a twin-screw extruder, and extruding and granulating to obtain the EVOH resin composition of this invention. The use of flake-shaped hexagonal boron nitride to fill EVOH resin in this invention can significantly improve the tensile strength and oxygen permeability of EVOH resin under high humidity. The product of this invention can be widely used in packaging, medical devices, automotive parts, building materials, and many other fields.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a modified EVOH resin composition and its preparation method. Background Technology

[0002] EVOH (ethylene-vinyl alcohol copolymer) is an alcoholysis product obtained by saponification or partial saponification of ethylene and vinyl alcohol. Its molecular chain contains hydroxyl groups, which easily form hydrogen bonds between hydroxyl groups, strengthening the intermolecular forces and making the molecular chain tightly packed, resulting in high crystallinity and thus excellent barrier properties.

[0003] Furthermore, EVOH resin possesses high mechanical strength, elasticity, surface hardness, abrasion resistance, and weather resistance, as well as strong antistatic properties. EVOH films exhibit high gloss and low haze, resulting in high transparency. EVOH resin also demonstrates strong oil and organic solvent resistance. After immersion in various solvents and oils for one year, the percentage increase in weight is as follows: 0% for solvents such as cyclohexane, xylene, petroleum ether, benzene, and acetone; 2.3% for ethylene glycol; 12.2% for methanol; and 0.1% for salad oil.

[0004] The barrier properties of EVOH depend on the ethylene content. Increased ethylene content decreases gas barrier properties but improves processability; conversely, decreased ethylene content increases gas barrier properties but deteriorates processability. Due to its thermal stability resulting from its bonding with ethylene, multilayer containers containing EVOH barrier layers are fully reusable. EVOH resin enhances flavor and quality retention by preventing oxygen penetration. In gas-filled packaging technology, EVOH resin effectively retains carbon dioxide or nitrogen used to protect the product. These characteristics allow plastic containers with EVOH barrier layers to replace many glass and metal containers in food packaging.

[0005] However, due to the presence of hydroxyl groups in the EVOH resin molecule, EVOH resin exhibits strong hydrophilicity and hygroscopicity. In high humidity environments, EVOH materials absorb moisture, causing changes in their internal structure and thus affecting their oxygen barrier properties. The water-absorbing EVOH film becomes porous, allowing oxygen to diffuse more easily through it. Furthermore, humidity changes also affect the film's mechanical properties and chemical stability, further impacting its barrier performance. Summary of the Invention

[0006] The purpose of this invention is to provide a modified EVOH resin composition and its preparation method to solve the problems in the prior art.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A modified EVOH resin composition is prepared from the following components in parts by weight:

[0009]

[0010]

[0011] In a further embodiment, the melt index of the EVOH resin at 230°C and 2.16 kg is 2-50 g / 10 min.

[0012] The plate-like hexagonal boron nitride is in the form of a white powder with an average particle size D50 of 200 nm-1 μm.

[0013] The antioxidants mentioned are selected from one or more of hindered phenols, thiolated compounds, hindered amines (HALS), and phosphites.

[0014] The antioxidant is selected from at least one of antioxidant 1076, antioxidant 1098, antioxidant 1010, and antioxidant 168.

[0015] A method for preparing an EVOH resin composition includes the following steps:

[0016] (1) Spray 0.05-0.2 parts of epoxytrimethoxysilane evenly onto the surface of 3-8 parts of flake hexagonal boron nitride, and air dry naturally to obtain modified flake hexagonal boron nitride;

[0017] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 90-100 parts of EVOH resin and 0.1-2 parts of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0018] In a further embodiment, in step (2), the processing parameters of the twin-screw extruder are: feeding section temperature 150℃-160℃, compression section temperature 190℃-210℃, plasticizing section temperature 200℃-220℃, homogenizing section temperature 210℃-220℃, and die head temperature 200-220℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0020] (1) Similar to the hexagonal carbon network in graphite, the hexagonal boron nitride (HN) crystals in the plate-like hexagonal boron nitride also form hexagonal network layers that overlap to form a crystal. In plate-like HN, N atoms are more electronegative than B atoms, with electrons mostly distributed on N atoms. On the one hand, in each h-BN layer, B atoms and N atoms are connected by covalent bonds, but due to the different electronegativity of B and N, these covalent bonds have characteristics similar to ionic bonds. On the other hand, the plates in plate-like HN are stacked in an AA-type configuration, and the alternating stacking of B and N atoms in adjacent layers produces a "lip-lip" effect, which greatly enhances the polar interaction between layers, giving it chemical inertness. In this invention, plate-like HN is used to fill EVOH resin, which can significantly improve the tensile strength of EVOH resin and the oxygen permeability under high humidity.

[0021] (2) This invention incorporates epoxytrimethoxysilane, which, through a "bridging" mechanism, links the plate-like hexagonal boron nitride with the surface groups of EVOH resin. This significantly improves the affinity between the plate-like hexagonal boron nitride and EVOH resin, thereby enhancing the mechanical and barrier properties of the EVOH resin composition. The product of this invention can be widely used in packaging, medical devices, automotive parts, building materials, and many other fields. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] The reagents used in this embodiment and their suppliers are as follows:

[0024] EVOH resin grade: DC3023RB, supplier: Japan Synthetic Chemical Industry Co., Ltd.

[0025] The sheet-like hexagonal boron nitride has an average particle size D50 of 100nm, 200nm, 500nm, 1μm, and 5μm; the spherical boron nitride has an average particle size D50 of 500nm; both are supplied by Shanghai Naio Nanotechnology Co., Ltd.

[0026] The suppliers of epoxytrimethoxysilane, aminomethoxysilane coupling agent, KH550, and KH560 are all Dow Corning Incorporated.

[0027] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1, and the manufacturer is BASF, Germany.

[0028] The reagents described above are only for illustrating the source and composition of the reagents used in the experiments of this invention, so as to provide full disclosure, and do not imply that the invention cannot be achieved by using other similar reagents or reagents provided by other suppliers.

[0029] Example 1

[0030] (1) 0.12 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 6 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0031] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0032] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0033] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 200 nm.

[0034] Example 2

[0035] (1) 0.12 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 6 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0036] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0037] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0038] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0039] Example 3

[0040] (1) 0.12 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 6 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0041] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0042] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0043] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 1 μm.

[0044] Example 4

[0045] (1) 0.08 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 4 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0046] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 95 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0047] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0048] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0049] Example 5

[0050] (1) 0.16 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 8 parts of flake hexagonal boron nitride and air-dried to obtain modified flake hexagonal boron nitride.

[0051] (2) The modified flake boron nitride in step (1) is mixed evenly with 91 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0052] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0053] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0054] Comparative Example 1

[0055] (1) 0.12 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 6 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0056] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0057] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0058] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 100 nm.

[0059] Comparative Example 2

[0060] (1) 0.12 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 6 parts of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0061] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0062] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0063] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 5 μm.

[0064] Comparative Example 3

[0065] (1) 0.08 parts of epoxytrimethoxysilane were uniformly sprayed onto the surface of 1 part of plate-shaped hexagonal boron nitride and air-dried to obtain modified plate-shaped hexagonal boron nitride.

[0066] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 95 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0067] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0068] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0069] Comparative Example 4

[0070] (1) 0.12 parts of silane coupling agent KH550 were evenly sprayed onto the surface of 6 parts of flake hexagonal boron nitride and air-dried naturally to obtain modified flake hexagonal boron nitride.

[0071] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0072] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0073] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0074] Comparative Example 5

[0075] (1) 0.12 parts of silane coupling agent KH560 were evenly sprayed onto the surface of 6 parts of flake hexagonal boron nitride and air-dried to obtain modified flake hexagonal boron nitride.

[0076] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0077] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0078] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0079] Comparative Example 6

[0080] (1) 0.12 parts of aminomethoxysilane coupling agent were evenly sprayed onto the surface of 6 parts of flake hexagonal boron nitride and air-dried to obtain modified flake hexagonal boron nitride.

[0081] (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0082] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0083] In this embodiment, the average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

[0084] Comparative Example 7

[0085] (1) 0.12 parts of epoxytrimethoxysilane were evenly sprayed onto the surface of 6 parts of spherical boron nitride and air-dried to obtain modified spherical boron nitride.

[0086] (2) The modified spherical boron nitride from step (1) is mixed evenly with 93 parts of EVOH resin and 1 part of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

[0087] The processing parameters for the twin-screw extruder are: feed section temperature 155℃, compression section temperature 200℃, plasticizing section temperature 210℃, homogenizing section temperature 220℃, and die head temperature 220℃.

[0088] In this embodiment, the average particle size D50 of the spherical boron nitride is 500 nm.

[0089] The performance test data of the products obtained in each embodiment and comparative example are shown in Table 1:

[0090] Table 1. Performance test data of the examples and comparative products.

[0091] Test Items / Units Tensile strength / MPa Oxygen permeability (65% RH, 20℃) cm³ / (m².d) Example 1 56.3 0.13 Example 2 55.6 0.12 Example 3 52.1 0.12 Example 4 50.4 0.16 Example 5 53.0 0.11 Comparative Example 1 49.8 0.26 Comparative Example 2 41.6 0.39 Comparative Example 3 38.2 0.43 Comparative Example 4 44.7 0.31 Comparative Example 5 45.3 0.28 Comparative Example 6 47.9 0.27 Comparative Example 7 43.5 0.42

[0092] Note: The tensile strength test specimen size is 150mm*10mm*4mm, the test standard is ISO 527-2-2012, and the tensile rate is 5mm / min; the barrier performance test is conducted using an oxygen permeability barrier tester (Jinan Sike Testing Technology Co., Ltd.), the standard is ASTM D3985, and the test range is 0.01~6500cm3 / (m2.d) for films.

[0093] As shown in Table 1, the tensile strength and oxygen permeability (65% RH, 20℃) of the EVOH resin composition are optimal when the average particle size of the lamellar hexagonal boron nitride is 500 nm. When the average particle size of the lamellar hexagonal boron nitride is 100 nm, agglomeration is more severe, and the performance deteriorates significantly. The performance also decreases to varying degrees when the average particle size of the lamellar hexagonal boron nitride is 5 μm, or when its content is less than 3 parts, or more than 8 parts.

[0094] Compared with common coupling agents KH550, KH560, and aminomethoxysilane coupling agents, the present invention uses epoxytrimethoxysilane to treat plate-shaped hexagonal boron nitride, resulting in a superior coupling effect. Compared with plate-shaped hexagonal boron nitride, spherical boron nitride provides only a limited increase in the tensile strength and barrier properties of EVOH resin.

[0095] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A modified EVOH resin composition, characterized in that: It is prepared from the following components in parts by weight:

2. The modified EVOH resin composition according to claim 1, characterized in that: The melt flow index of the EVOH resin at 230℃ and 2.16kg is 2-50g / 10min.

3. The modified EVOH resin composition according to claim 1, characterized in that: The plate-like hexagonal boron nitride is in the form of a white powder with an average particle size D50 of 200 nm-1 μm.

4. The modified EVOH resin composition according to claim 1, characterized in that: The average particle size D50 of the plate-like hexagonal boron nitride is 500 nm.

5. The modified EVOH resin composition according to claim 1, characterized in that: The antioxidant is selected from at least one of hindered phenols, thiolated compounds, hindered amines (HALS), and phosphites.

6. The modified EVOH resin composition according to claim 1, characterized in that: The antioxidant is selected from at least one of antioxidant 1076, antioxidant 1098, antioxidant 1010, and antioxidant 168.

7. A method for preparing a modified EVOH resin composition, characterized in that: Includes the following steps: (1) Spray 0.05-0.2 parts of epoxytrimethoxysilane evenly onto the surface of 3-8 parts of flake hexagonal boron nitride, and air dry naturally to obtain modified flake hexagonal boron nitride; (2) The modified flake hexagonal boron nitride from step (1) is mixed evenly with 90-100 parts of EVOH resin and 0.1-2 parts of antioxidant, and added from the feed port of a twin-screw extruder. The EVOH resin composition of the present invention is prepared by extrusion granulation.

8. The method for preparing a modified EVOH resin composition according to claim 6, characterized in that: In step (2), the processing parameters of the twin-screw extruder are: feeding section temperature 150℃-160℃, compression section temperature 190℃-210℃, plasticizing section temperature 200℃-220℃, homogenizing section temperature 210℃-220℃, and die head temperature 200-220℃.

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