Repeatedly bondable insert-moldable polyolefin material, its preparation method and application

Abstract

The present invention discloses a repeatedly bondable insert - moldable polyolefin material, its preparation method and application. The polyolefin material, by weight parts, comprises the following components: 70 - 90 parts of polyolefin resin, 5 - 20 parts of ethylene - vinyl acetate copolymer, 1 - 10 parts of polar block copolymer or polar graft, and 0.5 - 2 parts of oxidized low - molecular - weight polyethylene wax. The polyolefin material can achieve repeated metal bonding and has high metal bonding performance, and is particularly suitable for application scenarios where a high bonding force between the resin and the metal is required, and at the same time, after the resin is separated from the metal, the metal surface does not adhere to the resin.

Description

Technical Field

[0001] The present invention relates to the field of housing materials for metal insert products, and particularly to a polyolefin material for insert molding that can be adhesively bonded repeatedly, its preparation method and application. Background Art

[0002] Polyolefin resins have excellent insulation properties and high corrosion resistance, so they are commonly used as housing materials for metal insert products, such as motor rotors, motor housings, water pumps for household appliances, etc. However, since common polyolefin resins (polyethylene, polypropylene) are non-polar materials, they cannot effectively bond with metals, and it is easy to separate from the metal surface after long-term use. In the industry, PP-g-MAH or copolymers of propylene / ethylene and polar monomers (acrylic acid, vinyl acetate, etc.) are usually used to enhance the bonding ability between polyolefin resins and metals. However, due to the too high surface polarity, when the resin needs to be separated from the metal, resin adhesion will occur on the metal surface. Therefore, a polyolefin material with a high metal bonding force and capable of being adhesively bonded to metals repeatedly is needed, and there is no mature application solution on the market at present. Therefore, it is urgent to develop a polyolefin material for insert molding that can achieve repeated metal bonding and has high metal bonding performance. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention provides a polyolefin material for insert molding that can be adhesively bonded repeatedly. The present invention also provides a preparation method and application of the polyolefin material for insert molding that can be adhesively bonded repeatedly.

[0004] The present invention provides a polyolefin material for insert molding that can be adhesively bonded repeatedly, which comprises the following components in parts by weight:

[0005] 70 - 90 parts of polyolefin resin;

[0006] 5 - 20 parts of ethylene-vinyl acetate copolymer;

[0007] 1 - 10 parts of polar block copolymer or polar graft; the polar block copolymer is other polar block copolymers except ethylene-vinyl acetate copolymer.

[0008] 0.5 - 2 parts of oxidized low molecular weight polyethylene wax.

[0009] Further, the polyolefin resin is a copolymer of one or more of polyethylene, polypropylene, and ethylene-octene copolymer.

[0010] Further, the polyethylene is any one of low density polyethylene, linear low density polyethylene, high density polyethylene, and metallocene polyethylene.

[0011] Furthermore, the melt index of the polyolefin resin is 1-6 g / 10 min, preferably 1-5 g / 10 min (test conditions: 190 °C, 2.16 Kg), and the test method refers to GB / T 3682.1-2018.

[0012] Furthermore, the VA (vinyl acetate) content of the ethylene-vinyl acetate copolymer is 16-26%, preferably 20-26 wt%.

[0013] Furthermore, the melt index of the ethylene-vinyl acetate copolymer is 6-12 g / 10 min, preferably 6-10 g / 10 min (test conditions: 190 °C, 2.16 Kg), and the test method refers to GB / T 3682.1-2018.

[0014] Furthermore, the polar block copolymer is a composition of one or more of a copolymer of acrylic acid and ethylene, a copolymer of acrylic acid and propylene, a copolymer of butenoic acid and ethylene, and a copolymer of butenoic acid and propylene. The polar block copolymer forms hydrogen bonds or transesterification reactions through polar functional groups and polar groups on the metal surface.

[0015] Furthermore, the grafted product is a composition of one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, glycidyl methacrylate-grafted polyethylene, and glycidyl methacrylate-grafted polypropylene.

[0016] Furthermore, the weight-average molecular weight of the oxidized low-molecular-weight polyethylene wax is 800-2000.

[0017] Furthermore, the acid value of the oxidized low-molecular-weight polyethylene wax is 10-16 mg KOH / g, and the test method refers to ASTM D 1386-2015.

[0018] Furthermore, according to actual performance requirements, the repeatedly bondable insert-moldable polyolefin material of the present invention further includes 0-1 part by weight of an antioxidant and 0-1 part by weight of a processing aid.

[0019] Further, the antioxidant is selected from one or a mixture of several of phenolic antioxidants, phosphite antioxidants, divalent sulfur antioxidants or hindered amine antioxidants. Among them, the phenolic antioxidants include antioxidant 264, antioxidant 1010, antioxidant 1076, antioxidant SP, antioxidant 2246, antioxidant CA, antioxidant 330, Irganox1890 or antioxidant 3114; the phosphite antioxidants include antioxidant TNP, antioxidant ODP, antioxidant 168, Irganox1093 or Irganox1222; the divalent sulfur antioxidants include dilauryl thiodipropionate (DLTP), distearyl thiodipropionate (DSTP); the hindered amine antioxidants include LS-744, LS-770, GW-540 or Flamstab NOR116.

[0020] Further, the processing aid is selected from one or several of low molecular weight esters, metal soaps, stearic acid composite esters, amides. Among them, the low molecular weight esters are solid paraffin, liquid paraffin or low molecular weight polyolefin wax; the metal soaps are calcium stearate, magnesium stearate, zinc stearate or barium stearate; the stearic acid composite esters are ethylene glycol stearate, glycerol stearate or pentaerythritol stearate; the amides are erucic acid amide, methylene bis stearic acid amide or N,N-ethylene bis stearic acid amide.

[0021] The present invention also provides a preparation method of the repeatedly bondable insert molding polyolefin material, comprising the following steps:

[0022] After weighing each component by weight, the components are mixed evenly by a high-speed mixer, and then melt-extruded and granulated by a twin-screw extruder at 180-200 °C. After drying, a one-step material of the composition is obtained. Then, the one-step material of the composition is mixed evenly in a low-speed mixer and melt-extruded and granulated by a single-screw extruder at 150-170 °C to obtain the repeatedly bondable insert molding polyolefin material.

[0023] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0024] (1) The anhydride groups in maleic anhydride grafted polypropylene (PP-g-MAH) can well combine with the hydroxyl groups on the metal surface to form a stable chemical bond adhesion; the ester groups in ethylene-vinyl acetate copolymer (EVA) give the material surface a certain polarity, and at the same time, an ester exchange reaction occurs with the ester groups on the metal surface (the ester groups formed by the anhydride and the hydroxyl groups on the metal surface) at high temperature, converting the chemically bonded part into van der Waals bond adhesion between the two surfaces, realizing that no obvious resin adhesion occurs during the peeling process while ensuring high bonding strength. The polar block copolymer is through hydrogen bonding or transesterification reaction between polar functional groups and polar groups on the metal surface.

[0025] (2) The presence of oxidized low-molecular-weight polyethylene wax can not only provide higher polarity to the material surface through the hydroxyl / carboxyl groups after the oxidation of its molecular segments, but also the low-molecular-weight polyethylene segments have high fluidity and are prone to migrate to the material surface during the injection molding process, infiltrate the interface between the resin and the metal, increase the adhesion force of the two interfaces, and a suitable acid value will not cause the formation of chemical bond adhesion, which is beneficial to the subsequent peeling process without obvious resin adhesion. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic diagram of the sample for evaluating the metal bonding performance in the test method of the embodiment of the present invention. Detailed Embodiments

[0028] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Embodiment

[0030] The present invention will be further described below in conjunction with specific embodiments and comparative examples. The following specific embodiments are all preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following embodiments, especially not limited to the models of the raw materials of each component used in the following specific embodiments. In the embodiments, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0031] I. The raw materials of each component used are as follows:

[0032] Polyolefin resin #1: Polyethylene, low-density polyethylene (LDPE), grade LDPE 2102TN00, Qilu Petrochemical, melt index is 1 g / 10 min.

[0033] Polyolefin resin #2: Polypropylene, homopolypropylene HOPP by name, grade PP H030SG, Reliance Industries Limited, India, melt index is 5 g / 10 min.

[0034] Polyolefin resin #3: A mixture of metallocene polyethylene and polypropylene in a ratio of 1:1, grade LLDPE ENABLE 2010PA, ExxonMobil, USA, with a melt index of 3 g / 10 min.

[0035] Polyolefin resin #4: Polyethylene, low-density polyethylene (LDPE), grade LDPE 1905UMS, Sabic, with a melt index of 6 g / 10 min.

[0036] Ethylene-vinyl acetate copolymer #1: Grade Polybilt EVA 106, ExxonMobil, USA, with a vinyl acetate content of 20 wt%, and a melt index of 6 g / 10 min.

[0037] Ethylene-vinyl acetate copolymer #2: Grade EVA 11D554, Dow Chemical Company, with a vinyl acetate content of 26 wt%, and a melt index of 10 g / 10 min.

[0038] Ethylene-vinyl acetate copolymer #3: Grade EVA 1075A, Celanese Corporation, with a vinyl acetate content of 24 wt%, and a melt index of 8 g / 10 min.

[0039] Ethylene-vinyl acetate copolymer #4: Grade EVA 1125, Hanwha Chemical Materials Co., Ltd., with a vinyl acetate content of 18 wt%, and a melt index of 12 g / 10 min.

[0040] Polar block copolymer #1: Substance name acrylic acid-ethylene copolymer, grade EAA 3004, Dow Chemical Company.

[0041] Polar block copolymer #2: Substance name methacrylic acid-ethylene copolymer, grade EMA AX8900, SK Chemicals Co., Ltd.

[0042] Graft #1: Maleic anhydride grafted polypropylene, PP-g-MAH, grade BONDYRAM 1001CN, Prime Polymer Co., Ltd.

[0043] Graft #2: Substance name maleic anhydride grafted polyethylene, grade MC509A, Ningbo Nengzhiguang New Materials Co., Ltd.

[0044] Oxidized low molecular weight polyethylene wax #1: Grade PE-0530-10, Nanjing Tianshi New Materials, with a weight average molecular weight of 800 and an acid value of 10 mgKOH / g.

[0045] Oxidized low molecular weight polyethylene wax #2: Grade PE-204, Nanjing Tianshi New Materials, with a weight average molecular weight of 2000 and an acid value of 16 mgKOH / g.

[0046] Oxidized low molecular weight polyethylene wax #3: Grade PE-0530-13, Nanjing Tianshi New Materials, with a weight average molecular weight of 1400 and an acid value of 13 mgKOH / g.

[0047] Oxidized low molecular weight polyethylene wax #4: Grade PEW-0595, Nanjing Tianshi New Materials, with a weight average molecular weight of 3000 and an acid value of 20 mgKOH / g.

[0048] Antioxidant: phenolic antioxidant 1010, commercially available, and the same substance was used in parallel experiments.

[0049] Processing aid: calcium stearate, commercially available, and the same substance was used in parallel experiments.

[0050] The components and parts by weight of the polyolefin materials in the examples and comparative examples are shown in Tables 1 and 3.

[0051] The preparation method of the polyolefin materials in the examples and comparative examples includes the following steps:

[0052] After weighing each component by parts by weight, mix all components evenly through a high-speed mixer, then melt and extrude and pelletize at 180 - 200 °C through a twin-screw extruder. After drying, the one-step material of the composition is obtained. Then, after mixing the one-step material of the composition evenly in a low-speed mixer, melt and extrude and pelletize at 150 - 170 °C through a single-screw extruder to obtain the repeatedly bondable insert-moldable polyolefin material.

[0053] II. Product performance test standards and conditions:

[0054] 1. Preparation of samples for evaluating metal bonding performance: Use a 304 steel round sheet with a size of φ16mm * 1.0mm, and the resin is a resin plate with a size of 40mm * 25mm * 2mm, as Figure 1 shown. Hot press at 180 degrees for 1 minute with a load of 1KG. The resin plate and the steel sheet are partially connected, and the bonding area is half of the area of the round steel sheet.

[0055] 2. Plastic-metal peel test: Use a universal stress testing machine to test the peel strength between the above resin and metal combination, and the test method refers to GB / T 2790-1995 "Test Method for Peel Strength - Flexible Materials to Rigid Materials".

[0056] The test results are shown in Tables 2 and 3.

[0057] Table 1 Formulation composition of examples (parts by weight)

[0058]

[0059]

[0060] Table 2 Performance test results of the examples

[0061]

[0062] Table 3 Composition (parts by weight) of the comparative examples and performance test results

[0063]

[0064]

[0065] From the results of Examples 1-9, the properties of the polyolefin materials prepared by the formulations with different combinations can meet the bonding strength per unit area at room temperature ≥ 3.08 N / mm 2 , and the maximum can reach 4.55 N / mm 2 ; the bonding strength after the first peel and then re-bonding ≥ 2.89 N / mm 2 , and the maximum can reach 4.56 N / mm 2 ; the bonding strength after the second peel and then re-bonding ≥ 2.74 N / mm 2 , and the maximum can reach 4.33 N / mm 2 ; the bonding strength after the fifth peel and then re-bonding ≥ 2.65 N / mm 2 , and the maximum can reach 3.99 N / mm 2 ; and observing the adhesion after peeling, there is no sticky material or only slight sticky material.

[0066] Comparative Examples 1-6 are all single-variable with Example 1. In Comparative Example 1, ethylene-vinyl acetate copolymer is not added. In Comparative Example 2, low molecular weight oxidized polyethylene wax is not added. In Comparative Example 3, the dosage of ethylene-vinyl acetate copolymer is too low. In Comparative Example 4, the dosage of ethylene-vinyl acetate copolymer is too high. In Comparative Example 5, the dosage of the grafted product is too low. In Comparative Example 6, the dosage of the grafted product is too high. The polyolefin materials of the above comparative examples cannot achieve repeated metal bonding and at the same time have high metal bonding performance.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A repeatedly bondable insert molding polyolefin material, characterized in that, Comprising the following components by weight parts: 70 - 90 parts of polyolefin resin; 5 - 20 parts of ethylene - vinyl acetate copolymer; 1 - 10 parts of polar block copolymer; 0.5 - 2 parts of oxidized low - molecular - weight polyethylene wax; The polar block copolymer is a composition of one or more of copolymer of acrylic acid and ethylene, copolymer of acrylic acid and propylene, copolymer of butenoic acid and ethylene, copolymer of butenoic acid and propylene; The oxidized low - molecular - weight polyethylene wax has a weight - average molecular weight of 800 - 2000; The acid value of the oxidized low - molecular - weight polyethylene wax is 10 - 16mgKOH / g.

2. The polyolefin material according to claim 1, wherein The polyolefin resin is any one or more of polyethylene, polypropylene, ethylene - octene copolymer.

3. The polyolefin material according to claim 2, characterized in that, The polyethylene is any one of low - density polyethylene, linear low - density polyethylene, high - density polyethylene, metallocene polyethylene.

4. The polyolefin material according to claim 1, characterized in that The melt index of the polyolefin resin is 1 - 5g / 10min.

5. The polyolefin material according to claim 1, characterized in that, The vinyl acetate content of the ethylene - vinyl acetate copolymer is 20 - 26wt%.

6. The polyolefin material according to claim 1, characterized in that, The melt index of the ethylene - vinyl acetate copolymer is 6 - 10g / 10min.

7. The polyolefin material according to claim 1, wherein The polyolefin material further comprises an antioxidant and a processing aid.

8. The method for preparing the polyolefin material according to any one of claims 1-7, characterized in that, Comprising the following steps: After weighing each component by weight parts, mix each component evenly through a high - speed mixer, then melt - extrude and pelletize at 180 - 200°C through a twin - screw extruder. After drying, the one - step material of the composition is obtained. Then, after mixing the one - step material of the composition evenly in a low - speed mixer, melt - extrude and pelletize at 150 - 170°C through a single - screw extruder to obtain the polyolefin material.

9. Use of the polyolefin material according to any one of claims 1 - 7 in preparing the outer shell material of a metal insert product.

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