Preparation method of oxygen-absorbing master batch and product and application of oxygen-absorbing master batch

Abstract

The invention belongs to the field of food packaging and fresh keeping, and particularly relates to a preparation method, a product and application of an oxygen-absorbing master batch. The preparation method comprises the following steps: respectively preparing a component A (58-70 parts of MXD6, 2-4 parts of PET and PET-Co-PEI) and a component B (15-30 parts of PET and 1-2 parts of cobalt stearate), then mixing the component A and the component B according to the total mass of 100 parts, carrying out melt blending, and carrying out twin-screw extrusion granulation to obtain the oxygen-absorbing master batch. The obtained oxygen-absorbing master batch product does not generate black spots after being continuously used at high temperature within 10 hours, the oxygen is reduced to PPM level in 24 hours, and the oxygen-absorbing master batch product has the functions of passive blocking and active oxygen absorption, can prolong the shelf life of food, and is suitable for food packaging.

Description

Technical Field

[0001] This application belongs to the field of food packaging and preservation technology, and specifically relates to a method for preparing oxygen-absorbing masterbatch, its products, and its uses. Background Technology

[0002] Specialty nylon MXD6 (poly(m-phenylene adipamide)) has become a preferred alternative to traditional high-barrier packaging materials due to its excellent gas barrier properties, transparency, and mechanical properties. Its applications in the packaging field are not limited to providing passive oxygen barrier properties for chilled meat and baked goods to extend shelf life; it can also be used as a functional carrier to prepare oxygen-absorbing masterbatches, developing dual-function intelligent packaging that combines passive barrier properties with active oxygen absorption. This precisely matches the long-term preservation needs of fresh and ready-to-eat foods, effectively solving the problem that traditional packaging struggles to balance barrier properties with active oxygen removal, demonstrating significant application value in the high-end food packaging sector.

[0003] In existing technologies, the preparation of oxygen-absorbing masterbatch uses MXD6 as the core basic component, compounded with PET (polyethylene terephthalate) and transition metal catalysts. MXD6 provides high barrier properties and support, ensuring stable dispersion of the oxygen-absorbing masterbatch in packaging and maintaining its barrier performance. PET is used to adjust the flowability of the masterbatch during processing, forming a synergistic blend system with MXD6. The transition metal catalyst acts as the active oxygen-absorbing component, activating the reaction between the masterbatch and oxygen to achieve active oxygen consumption. The preparation process often employs a screw melt blending process, controlling temperature and rotation speed to ensure uniform mixing of the components, producing a functional masterbatch that can be compounded with a base resin.

[0004] However, existing technologies have significant technical problems: during screw processing, MXD6 is prone to carbonization and black spots due to continuous high-temperature shearing. This problem not only damages the packaging appearance but also impairs the barrier structure of MXD6, reduces the efficiency of oxygen-absorbing masterbatch, and even poses food contact safety hazards, thus hindering the industrial application of related packaging materials. Summary of the Invention

[0005] This invention provides a method for preparing oxygen-absorbing masterbatch. By adding the dispersant PET-Co-PEI (polyethylene terephthalate-polyetherimide copolymer) to a polymer blend containing MXD6 and PET resin, a temporary linking of MXD6 and PET is achieved, thereby improving the dispersibility of MXD6 in the polymer blend. The resulting oxygen-absorbing masterbatch exhibits high transparency, does not produce black spots even after continuous high-temperature use, and has high oxygen absorption efficiency. The specific preparation steps include the following: S1. Blending: Prepare component A and component B by mass parts, wherein component A contains MXD6, PET resin and dispersant PET-Co-PEI, and component B contains PET resin and transition metal catalyst; mix the raw materials of component A and component B evenly. S2. Granulation: Mix components A and B from step S1 at a ratio of 100 parts by total mass, and obtain oxygen-absorbing masterbatch by melt blending, extrusion, cooling, and pelletizing.

[0006] Preferably, by mass parts, component A comprises: 58-70 parts of MXD6, 6-15 parts of PET resin, and 2-4 parts of dispersant PET-Co-PEI; component B comprises: 15-30 parts of PET resin and 1-2 parts of transition metal catalyst.

[0007] Furthermore, the relative molecular mass of MXD6 is 33,000, and the melting point is 240°C.

[0008] Furthermore, the transition metal catalyst is a cobalt salt; More preferably, the cobalt salt is cobalt stearate; Furthermore, the cobalt stearate has a purity of 99%.

[0009] Optionally, in step S1, the mixing is carried out in a high-speed mixer with a rotation speed of 486 r / min-860 r / min and a mixing time of 5 min-10 min.

[0010] Optionally, in step S2, the melt blending and extrusion are carried out using a twin-screw extruder with a screw speed of 300-600 r / min and an extrusion temperature of 240-280℃; the cooling temperature is 40-50℃.

[0011] On the other hand, the present invention provides an oxygen-absorbing masterbatch, which is prepared by the above method.

[0012] In another aspect, the present invention provides an application of oxygen-absorbing masterbatch in the preparation of food packaging materials. The application refers to integrating the oxygen-absorbing masterbatch prepared by the above method into the interior or structure of a main packaging container made of a high-barrier material, namely PET, by melt blending.

[0013] Compared with existing technical solutions, the present invention has the following technical effects: This invention completely solves the problem of MXD6 carbonization and black spots, improving packaging appearance and safety. In existing technologies, MXD6 easily carbonizes and produces black spots under high-temperature shearing (240-260℃) using a screw extruder. For example, imported oxygen-absorbing masterbatch develops black spots after 6 hours of continuous use at 240℃, while domestic masterbatch develops black spots after only 5 hours. These black spots damage the barrier structure and pose food contact safety hazards. This invention adds the dispersant PET-Co-PEI, which temporarily links MXD6 to PET resin. Combined with a specific ratio of component A (58-70 parts MXD6, 6-15 parts PET, 2-4 parts PET-Co-PEI) and component B (15-30 parts PET, 1-2 parts cobalt stearate), MXD6 is evenly dispersed in the blend system, avoiding localized aggregation and repeated heating for carbonization. The oxygen-absorbing masterbatch of this invention shows no black spots even after 10 hours of continuous processing, completely resolving the appearance and safety risks caused by black spots in existing technologies. Detailed Implementation

[0014] The following embodiments are merely illustrative of the present invention and do not limit the scope of protection of the present invention in any way. For those skilled in the art, all equivalent implementations or modifications made without departing from the spirit of the present invention are within the scope of protection of the present invention.

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments.

[0016] The following description of the materials used in the embodiments: MXD6 has a relative molecular mass of 33,000 and a melting point of 240°C. The dispersant PET-Co-PEI was purchased from Sinopec Yizheng Chemical Fiber Co., Ltd. The purity of cobalt stearate is 99%.

[0017] Example 1: Preparation of component A: Weigh 58 parts of MXD6, 15 parts of PET resin, and 2 parts of dispersant PET-Co-PEI and place them in a high-speed mixer. Mix for 7 minutes at a speed of 500 r / min. Preparation of component B: Weigh 24 parts of PET resin and 1 part of cobalt stearate and place them in a high-speed mixer. Mix for 5 minutes at a speed of 500 r / min. Granulation: The mixed components A and B are fed into a twin-screw extruder for melt blending and extrusion. The screw speed of the twin-screw extruder is 570 r / min and the extrusion temperature is 260℃. After extrusion, the mixture is cooled to 40℃ and pelletized to obtain oxygen-absorbing masterbatch.

[0018] Example 2: Preparation of component A: Weigh 70 parts of MXD6, 6 parts of PET resin, and 4 parts of dispersant PET-Co-PEI and place them in a high-speed mixer. Mix for 7 minutes at a speed of 500 r / min. Preparation of component B: Weigh 18 parts of PET resin and 2 parts of cobalt stearate and place them in a high-speed mixer. Mix for 5 minutes at a speed of 500 r / min. Granulation: The mixed components A and B are fed into a twin-screw extruder for melt blending and extrusion. The screw speed of the twin-screw extruder is 570 r / min and the extrusion temperature is 260℃. After extrusion, the mixture is cooled to 50℃ and pelletized to obtain oxygen-absorbing masterbatch.

[0019] Example 3: Preparation of component A: Weigh 60 parts of MXD6, 6 parts of PET resin, and 3 parts of dispersant PET-Co-PEI and place them in a high-speed mixer. Mix for 7 minutes at a speed of 500 r / min. Preparation of component B: Weigh 30 parts of PET resin and 1 part of cobalt stearate and place them in a high-speed mixer. Mix for 5 minutes at a speed of 500 r / min. Granulation: The mixed components A and B are fed into a twin-screw extruder for melt blending and extrusion. The screw speed of the twin-screw extruder is 570 r / min and the extrusion temperature is 260℃. After extrusion, the mixture is cooled to 50℃ and pelletized to obtain oxygen-absorbing masterbatch.

[0020] Example 4: The oxygen-absorbing masterbatch from Examples 1-3 was blended at 2% with 98% bottle-grade PET. After high-speed mixing, a two-step blow molding process was used: injection molding of preforms at a barrel temperature of 250°C and a screw speed of 50 rpm; and stretch blow molding of bottles at a preheating temperature of 100°C and a stretch ratio of 1:2.5.

[0021] Example 5: The oxygen-absorbing masterbatch from Examples 1-3 was blended at 2% with 98% sheet-grade PET. Sheets were extruded using a single screw extruder at a barrel temperature of 230°C and a rotation speed of 25 rpm, followed by three-roll calendering to obtain 0.4 mm thick sheets. Vacuum forming was then performed, with preheating at 140°C and a vacuum degree of -0.09 MPa.

[0022] Comparative Example 1: Preparation of component A: Weigh 58 parts of MXD6, 15 parts of PET resin, and 2 parts of maleic anhydride graft copolymer dispersant and place them in a high-speed mixer. Mix for 7 minutes at a speed of 500 r / min. Preparation of component B: Weigh 24 parts of PET resin and 1 part of cobalt stearate and place them in a high-speed mixer. Mix for 5 minutes at a speed of 500 r / min. Granulation: The mixed components A and B are first added to a twin-screw extruder for melt blending and extrusion. The screw speed of the twin-screw extruder is 570 r / min and the extrusion temperature is 260℃. After extrusion, the mixture is cooled to 60℃ and pelletized to obtain oxygen-absorbing masterbatch.

[0023] Comparative Example 2: Preparation of component A: Weigh 70 parts of MXD6 and 6 parts of PET resin, place them in a high-speed mixer, and mix for 7 minutes at a speed of 500 r / min; Preparation of component B: Weigh 22 parts of PET resin and 2 parts of cobalt stearate and place them in a high-speed mixer. Mix for 5 minutes at a speed of 500 r / min. Granulation: The mixed components A and B are first added to a twin-screw extruder for melt blending and extrusion. The screw speed of the twin-screw extruder is 570 r / min and the extrusion temperature is 260℃. After extrusion, the mixture is cooled to 60℃ and pelletized to obtain oxygen-absorbing masterbatch.

[0024] Black spot generation test: The oxygen-absorbing masterbatches prepared in Examples 1-3 and Comparative Examples 1-2, as well as the domestically produced oxygen-absorbing masterbatches purchased from Dongguan Hanhui Coatings Co., Ltd. and the imported oxygen-absorbing masterbatches purchased from The Valspar Corporation, were sheared at high temperatures of 240℃, 250℃, and 260℃, and extruded continuously to produce sheets. The time it took for black spots to appear in the sheets was measured and recorded. The test results are shown in Table 1.

[0025] Table 1: Time for black spots to appear after continuous use of each oxygen-absorbing masterbatch

[0026] As shown in Table 1, the present invention (Examples 1-3) effectively solves the industry problem of MXD6 easily carbonizing and producing black spots during high-temperature processing by adding a specific dispersant PET-Co-PEI, and significantly improves the processing stability and safety of the masterbatch.

Claims

1. A process for the preparation of an oxygen absorbing masterbatch, characterized in that, Includes the following steps: S1. Blending: Prepare component A and component B by mass parts, wherein component A contains MXD6, PET resin and dispersant PET-Co-PEI, and component B contains PET resin and transition metal catalyst; mix the raw materials of component A and component B evenly. S2. Granulation: Mix components A and B from step S1 at a ratio of 100 parts by total mass, and obtain oxygen-absorbing masterbatch by melt blending, extrusion, cooling, and pelletizing.

2. The preparation method according to claim 1, characterized in that, By mass, component A comprises 58-70 parts of MXD6, 6-15 parts of PET resin, and 2-4 parts of dispersant PET-Co-PEI; component B comprises 15-30 parts of PET resin and 1-2 parts of transition metal catalyst.

3. The preparation method according to claim 2, characterized in that, The transition metal catalyst is a cobalt salt.

4. The preparation method according to claim 3, characterized in that, The cobalt salt is cobalt stearate.

5. The preparation method according to claim 1, characterized in that, In step S1, the mixing is carried out in a high-speed mixer with a rotation speed of 486 r / min-860 r / min and a mixing time of 5 min-10 min.

6. The preparation method according to claim 1, characterized in that, In step S2, the melt blending and extrusion refer to the process carried out using a twin-screw extruder with a screw speed of 300-600 r / min and an extrusion temperature of 240-280℃; the cooling temperature is 40-50℃.

7. An oxygen-absorbing masterbatch, characterized in that, It is prepared according to any one of claims 1-6.

8. The application of an oxygen-absorbing masterbatch in the preparation of food packaging materials, characterized in that, The oxygen-absorbing masterbatch of claim 7 is integrated into the interior or structure of a main packaging container made of a high-barrier material by melt blending.

9. The application of the oxygen-absorbing masterbatch according to claim 8 in the preparation of food packaging materials, characterized in that, The high-barrier material is PET.

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