POM composition as well as preparation method and application thereof

Abstract

The invention provides a POM composition as well as a preparation method and application thereof. The POM composition comprises POM resin, TPV (thermoplastic vulcanizate), polycarbodiimide, an ethylene-vinyl alcohol copolymer and an antioxidant. Through the mutual matching of the components, especially the synergistic compounding of the polycarbodiimide and the ethylene-vinyl alcohol copolymer, and the selection of TPV as an elastomer, the obtained POM composition also has excellent ozone resistance and polar solvent resistance on the premise of having high toughness, and can be used for preparing the high-toughness POM composition. Therefore, the problems of color change, pulverization, performance reduction and the like are not easy to occur in the use process.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a POM composition, a preparation method and an application thereof. Background Art

[0002] Polyoxymethylene (POM), as an engineering plastic with excellent comprehensive performance, has excellent wear resistance and self-lubricating properties, and is widely used in products such as automobiles, office equipment, and printers.

[0003] However, due to its own structure, POM has poor toughness and poor resistance to ozone and some polar solvents (such as ethanol). As a result, its products are prone to discoloration, powdering, and performance degradation, which seriously affects its use effect.

[0004] Therefore, developing a POM composition with high toughness, excellent ozone resistance and polar solvent resistance is still a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a POM composition, a preparation method and an application thereof. The POM composition has high toughness as well as excellent ozone resistance and polar solvent resistance, and is therefore not prone to problems such as discoloration, powdering and performance degradation during use.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a POM composition, comprising the following components in parts by weight:

[0008]

[0009]

[0010] The POM composition provided by the present invention includes a POM resin, an elastomer, an ethylene-vinyl alcohol copolymer (EVOH) and an antioxidant. Through the coordinated combination of the above components, in particular, by selecting polycarbodiimide and EVOH to produce a synergistic effect, and selecting the TPV as the elastomer, while ensuring that the obtained POM composition has high toughness, the ozone resistance and polar solvent resistance of the obtained POM composition are effectively improved, so that the product prepared using the POM composition is not prone to problems such as discoloration, powdering and performance degradation during use.

[0011] In the present invention, the mass percentage of the POM resin in the POM composition is not less than 80%.

[0012] The amount of TPV can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight or 15 parts by weight.

[0013] The content of the polycarbodiimide can be 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.55 parts by weight or 0.6 parts by weight.

[0014] The amount of the ethylene-vinyl alcohol copolymer can be 1 part by weight, 1.1 parts by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight, 1.9 parts by weight or 2 parts by weight.

[0015] The amount of the antioxidant can be 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, 0.8 parts by weight, 1 part by weight or 1.2 parts by weight.

[0016] In some preferred embodiments, the POM resin includes a homopolymer POM resin and / or a copolymer POM resin, and more preferably a copolymer POM resin.

[0017] In some preferred embodiments, the melt index of the copolymerized POM resin at 190°C and 2.16 kg is ≤27 g / 10min, for example, 1 g / 10min, 2.5 g / 10min, 5 g / 10min, 7 g / 10min, 9 g / 10min, 11 g / 10min, 13 g / 10min, 15 g / 10min, 17 g / 10min, 19 g / 10min, 21 g / 10min, 23 g / 10min, 25 g / 10min or 27 g / 10min, and more preferably 1 to 7 g / 10min.

[0018] In some preferred embodiments, the melt index of the homopolymer POM resin at 190°C and 2.16 kg is 1 to 25 g / 10 min, for example, 1 g / 10 min, 2 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min or 25 g / 10 min, etc.

[0019] In the present invention, the melt index of the homopolymer POM resin and the copolymer POM resin can be tested according to the method provided in the ISO 1133-1:2011 standard.

[0020] In some preferred embodiments, the hardness of the TPV is 50-100A, such as 50A, 60A, 70A, 80A, 90A or 100A.

[0021] In the present invention, the hardness of the TPV can be measured using a Shore durometer.

[0022] In some preferred embodiments, the melting point of the ethylene-vinyl alcohol copolymer is 140-210°C, for example, 140°C, 150°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 200°C or 210°C, and more preferably 160-190°C.

[0023] In the present invention, the melting point of the ethylene-vinyl alcohol copolymer can be tested with reference to the test method provided in the ISO 11357-1:2023 standard.

[0024] In some preferred embodiments, the mass percentage of ethylene units in the ethylene-vinyl alcohol copolymer is 20-45%, for example, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44% or 45%, etc.

[0025] In the present invention, the mass percentage of ethylene units in the ethylene-vinyl alcohol copolymer can be obtained by gas chromatography.

[0026] In some preferred embodiments, the mass ratio of the polycarbodiimide to the ethylene-vinyl alcohol copolymer is 1:(2-18), for example, 1:2, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:12, 1:14, 1:16 or 1:18, and more preferably 1:(3-10).

[0027] In some preferred embodiments, the antioxidant includes any one of a hindered amine antioxidant, a hindered phenol antioxidant, a phosphite antioxidant, or a thioester antioxidant, or a combination of at least two thereof.

[0028] For example, the antioxidant may be selected from antioxidant 1010, antioxidant 168, antioxidant 245, and the like.

[0029] In some preferred embodiments, the POM composition further comprises other additives.

[0030] In some preferred embodiments, the content of other additives in the POM composition is 1 to 10 parts by weight, for example, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 7 parts by weight, 9 parts by weight or 10 parts by weight, etc.

[0031] In some preferred embodiments, the other additives include any one of a lubricant, an anti-wear agent, or a weathering agent, or a combination of at least two thereof.

[0032] In some preferred embodiments, the content of the lubricant in the POM composition is 0.1 to 0.5 parts by weight, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, or 0.5 parts by weight.

[0033] For example, the lubricant may be selected from ethylene bisstearamide (EBS), oleamide, stearate, polyethylene wax, and the like.

[0034] In some preferred embodiments, the content of the wear-resistant agent in the POM composition is 0.5 to 10 parts by weight, for example, 0.5 parts by weight, 1 part by weight, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight or 10 parts by weight.

[0035] For example, the anti-wear agent may be selected from polytetrafluoroethylene, molybdenum disulfide, graphite, glass fiber, etc.

[0036] In some preferred embodiments, the content of the weathering agent in the POM composition is 0.2 to 2 parts by weight, for example, 0.2 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight or 2 parts by weight.

[0037] In some more preferred embodiments, the weathering agent includes a benzotriazole weathering agent and / or a hindered amine weathering agent.

[0038] For example, the weathering agent may be UV-234, UV-622, or the like.

[0039] In some preferred embodiments, the POM composition further comprises a filler.

[0040] In some preferred embodiments, the content of filler in the POM composition is 1 to 50 parts by weight, for example, 1 part by weight, 5 parts by weight, 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight or 50 parts by weight.

[0041] Illustratively, the filler includes glass microbeads, talc, wollastonite, magnesium hydroxide, and the like.

[0042] In a second aspect, the present invention provides a method for preparing the POM composition as described in the first aspect, the preparation method comprising: mixing the components according to their respective amounts, melt-extruding, cooling and granulating to obtain the POM composition.

[0043] In some preferred embodiments, the melt extrusion is performed in a twin-screw extruder.

[0044] In some preferred embodiments, the temperature of each screw barrel of the twin-screw extruder from the feed port to the die head is: 150-170°C (for example, 150°C, 152°C, 154°C, 156°C, 158°C, 160°C, 162°C, 164°C, 166°C, 168°C or 170°C), 170-180°C (for example, 170°C, 172°C, 174°C, 176°C, 178°C, 179°C, 180°C, 181°C, 182°C, 183°C, 184°C, 186°C, 187°C, 188°C, 189°C, 190°C, 200°C, 201°C, 202°C, 203°C, 204°C, 205°C, 206°C, 207°C, 208°C, 209°C, 210°C, 211°C, 212°C, 213°C, 214°C, 215°C, 216°C, 217°C, 8℃ or 180℃, etc.), 170-190℃ (e.g., 170℃, 172℃, 174℃, 176℃, 178℃, 180℃, 182℃, 184℃, 186℃, 188℃ or 190℃, etc.), 170-200℃ (e.g., 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 170-200℃ (e.g., 1 70℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 170~200℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 170~200℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 170~200℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 0℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.), 170-200℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.) and 170-200℃ (for example, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃, etc.).

[0045] In some preferred embodiments, the screw speed of the twin-screw extruder is 200-300 rpm (e.g., 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm or 300 rpm, etc.), and the feed rate is 50-200 kg / h (e.g., 50 kg / h, The pressure relief valve can be 70kg / h, 90kg / h, 110kg / h, 130kg / h, 150kg / h, 170kg / h, 180kg / h or 200kg / h, etc.), and the vacuum degree is -0.1 to 0MPa (for example, -0.1MPa, -0.09MPa, -0.08MPa, -0.07MPa, -0.06MPa, -0.04MPa, -0.02MPa or -0.01MPa, etc.).

[0046] In a third aspect, the present invention provides a use of the POM composition described in the first aspect in automobiles, office equipment or medical devices.

[0047] Specifically, it can be applied to automobile housings, office equipment (such as printer) housings, or medical equipment housings.

[0048] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The POM composition provided by the present invention includes a POM resin, an elastomer, a polycarbodiimide, an ethylene-vinyl alcohol copolymer, and an antioxidant. By combining the above components, in particular by synergistically compounding the polycarbodiimide and the ethylene-vinyl alcohol copolymer and selecting the TPV as the elastomer, the obtained POM composition has high toughness as well as excellent ozone resistance and polar solvent resistance. Therefore, the composition is not prone to discoloration, powdering, or performance degradation during use. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] Some of the raw material information involved in the specific implementation of the present invention is as follows:

[0053] (1)POM resin

[0054] POM resin A: copolymer POM resin, melt index 2.5 g / 10 min (190 ° C / 2.16 kg), purchased from Polyplastics Co., Ltd., Japan, brand M25-44;

[0055] POM resin B: copolymer POM resin, melt index 9 g / 10 min (190 ° C / 2.16 kg), purchased from Japan Polyplastics, brand M90-44;

[0056] POM resin C: homopolymer POM resin, melt index of 15 g / 10 min (190° C. / 2.16 kg), purchased from DuPont, USA, brand 500P NC010.

[0057] (2) Elastomer

[0058] TPV: hardness 85A, purchased from Celanese, brand SLD 903;

[0059] SBS: purchased from Yueyang Petrochemical, brand YH-796;

[0060] SEBS: purchased from Kraton, USA, brand name G1650MU.

[0061] (3) Polycarbodiimide: purchased from Rhein Chemie, brand name STABAXOL-P.

[0062] (4) Ethylene-vinyl alcohol copolymer

[0063] Ethylene-vinyl alcohol copolymer A: melting point 188 ° C, purchased from Japan Synthetic Chemical Industry, brand EVOH-29;

[0064] Ethylene-vinyl alcohol copolymer B: melting point 200 °C, purchased from Japan Synthetic Chemical Industry, brand EVOH-25;

[0065] Ethylene-vinyl alcohol copolymer C: melting point of 150°C, purchased from Japan Synthetic Chemical Industry, brand EVOH-20.

[0066] (5) Antioxidants

[0067] Antioxidant 245: purchased from BASF (China) Co., Ltd.

[0068] Examples 1 to 10 and Comparative Examples 1 to 8

[0069] Examples 1 to 10 and Comparative Examples 1 to 8 respectively provide a POM composition, the components and amounts thereof are shown in Tables 1 and 2 below. In Tables 1 and 2, the amount of each component is expressed in parts by weight.

[0070] Table 1

[0071]

[0072] Table 2

[0073]

[0074]

[0075] The preparation method of the POM composition provided in Examples 1 to 10 and Comparative Examples 1 to 8 comprises: mixing the components according to their respective amounts for 2 minutes, and melt-extruding in a twin-screw extruder, wherein the temperatures of the screw barrels from the feeding port to the die of the twin-screw extruder are: 160°C, 175, 180°C, 190°C, 190°C, 190°C, 190°C, 190°C, 190°C and 190°C, respectively, the screw speed is 250 rpm, the feed rate is 150 kg / h, the vacuum degree is -0.9 MPa, and then cooling and granulating to obtain the POM composition.

[0076] Performance testing:

[0077] (1) Charpy notched impact strength: The test temperature is 23°C and the test is carried out according to the method provided in ISO 179-1:2023.

[0078] (2) Ozone resistance: The standard specimens were stored at a test temperature of 40°C and an ozone concentration of 50 pphm for half a month. The surface of the standard specimens was observed for powdering and discoloration before and after the test. The tensile strength of the standard specimens after the test was measured and divided by the initial tensile strength before storage to obtain the tensile strength retention rate. The tensile strength was tested according to the method provided in ISO 527-2:2012.

[0079] (3) Ethanol gasoline resistance: Standard tensile specimens were placed in ethanol gasoline at 95°C. The tensile strength was measured after 1000 hours and the tensile strength was divided by the initial tensile strength before placement to obtain the tensile strength retention rate. The tensile strength was tested according to the method provided in ISO 527-2:2012.

[0080] The POM compositions provided in Examples 1 to 10 and Comparative Examples 1 to 8 were tested according to the above test method. The test results are shown in Table 3:

[0081] Table 3

[0082]

[0083] According to the data in Table 3, we can see that:

[0084] The POM compositions provided in Examples 1 to 10 have a simple supported beam notched impact strength of 12.3 to 14.7 kJ / m2 After ozone treatment, no obvious powdering or discoloration occurred on the surface, and the tensile strength retention rate was not less than 95.6%. At the same time, the tensile strength retention rate after ethanol gasoline treatment was not less than 85.6%, and the POM compositions provided in Examples 1 to 4 had excellent impact resistance, ozone resistance, and polar solvent resistance. In particular, the POM compositions provided in Examples 1 to 4 had a simple supported beam notched impact strength of up to 13.8 to 14.7 kJ / m 2 The tensile strength retention rate after ozone treatment is as high as 97.2-98.5%, and the tensile strength retention rate after ethanol gasoline treatment is as high as 91.6-93.5%. It has the best impact resistance, ozone resistance and polar solvent resistance.

[0085] Comparing the data of Example 1 and Comparative Examples 1 to 4, it can be seen that no ethylene-vinyl alcohol copolymer is added (Comparative Example 1), the amount of ethylene-vinyl alcohol copolymer is too low (Comparative Example 2), no polycarbodiimide is added (Comparative Example 3), and the amount of polycarbodiimide is too low (Comparative Example 4), all of which will lead to a deterioration in the synergistic effect of ethylene-vinyl alcohol copolymer and polycarbodiimide, which in turn leads to a slight discoloration of the surface of the obtained POM composition after ozone treatment, and a significant decrease in the tensile strength retention rate after ozone treatment and ethanol gasoline treatment, deterioration of ozone resistance and polar solvent resistance, and a slight decrease in the simply supported beam notched impact strength and deterioration of impact resistance.

[0086] Comparing the data of Example 1 and Comparative Examples 5 to 6, it can be seen that when the total amount of ethylene-vinyl alcohol copolymer and anti-hydrolysis agent added is too low (Comparative Example 5) or too high (Comparative Example 6), the surface of the obtained POM composition will change color after ozone treatment, and the tensile strength retention rate after ozone treatment and ethanol gasoline treatment will decrease significantly, and the ozone resistance and polar solvent resistance will deteriorate. At the same time, the simply supported beam notched impact strength will decrease slightly, and the impact resistance will deteriorate.

[0087] Further comparison of the data of Example 1 and Comparative Examples 7 to 8 shows that using SEBS and SBS instead of TPV as the elastomer will also cause slight powdering of the surface of the resulting POM composition, with a slight color change, and a significant decrease in the tensile strength retention rate after ozone treatment and ethanol gasoline treatment, indicating that the ozone resistance and polar solvent resistance have deteriorated.

[0088] Finally, by comparing the data of Example 1 and Examples 5 to 10, it can be seen that the melt index of the POM resin, the type selection, the ratio of polycarbodiimide to ethylene-vinyl alcohol copolymer, and the melting point of the ethylene-vinyl alcohol copolymer will also affect the impact resistance, ozone resistance and polar solvent resistance of the final POM composition. Selecting a suitable POM resin, a suitable ethylene-vinyl alcohol copolymer and setting a suitable ratio of polycarbodiimide to ethylene-vinyl alcohol copolymer will help to obtain a POM composition with the best impact resistance, ozone resistance and polar solvent resistance.

[0089] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A POM composition, characterized in that The POM composition comprises the following components in parts by weight: 100 parts by weight of POM resin; TPV 5-15 parts by weight; 0.1-0.6 parts by weight of polycarbodiimide; 1-2 parts by weight of ethylene-vinyl alcohol copolymer; 0.2-1.2 parts by weight of antioxidant 2. The POM composition according to claim 1, characterized in that The POM resin includes copolymerized POM resin and / or homopolymerized POM resin, preferably copolymerized POM resin.

3. The POM composition according to claim 2, characterized in that The melt index of the copolymerized POM resin at 190° C. and 2.16 kg is ≤27 g / 10 min, preferably 1 to 7 g / 10 min; Preferably, the homopolymer POM resin has a melt index of 1 to 25 g / 10 min at 190° C. and 2.16 kg.

4. The POM composition according to any one of claims 1 to 3, characterized in that The melting point of the ethylene-vinyl alcohol copolymer is 140-210°C, preferably 160-190°C.

5. The POM composition according to any one of claims 1 to 4, characterized in that The mass ratio of the polycarbodiimide to the ethylene-vinyl alcohol copolymer is 1:(2-18), preferably 1:(3-10).

6. The POM composition according to any one of claims 1 to 5, characterized in that The POM composition also includes other additives; Preferably, the content of other additives in the POM composition is 1 to 10 parts by weight; Preferably, the other additives include any one of a lubricant, an anti-wear agent or a weathering agent, or a combination of at least two thereof.

7. The POM composition according to any one of claims 1 to 6, characterized in that The POM composition further includes a filler; Preferably, the content of filler in the POM composition is 1 to 50 parts by weight.

8. A method for preparing the POM composition according to any one of claims 1 to 7, characterized in that: The preparation method comprises: mixing the components according to their respective usage amounts, performing melt extrusion, cooling and granulation to obtain the POM composition.

9. The preparation method according to claim 8, characterized in that The melt extrusion is carried out in a twin-screw extruder; Preferably, the temperatures of the screw barrels of the twin-screw extruder from the feed port to the die are: 150-170°C, 170-180°C, 170-190°C, 170-200°C, 170-200°C, 170-200°C, 170-200°C, 170-200°C, 170-200°C, 170-200°C and 170-200°C respectively; Preferably, the screw speed of the twin-screw extruder is 200 to 300 rpm, the feed rate is 50 to 200 kg / h, and the vacuum degree is -0.1 to 0 MPa.

10. Use of the POM composition according to any one of claims 1 to 7 in automobiles, office equipment or medical devices.

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