A homopolymer POM composition, its preparation method and application

Abstract

The present invention discloses a homopolymer POM composition, a preparation method and an application thereof. The homopolymer POM composition comprises the following components in parts by weight: 100 parts of homopolymer POM resin; 0.2 - 0.6 part of dialkyl adipate; 0.1 - 0.6 part of ethylene-vinyl alcohol copolymer; 0.2 - 0.6 part of a primary antioxidant; and 0.2 - 0.4 part of a secondary antioxidant. The homopolymer POM composition provided by the present invention has good thermal stability, is not easily decomposed by heat, is not easily yellowed, and does not easily release formaldehyde.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and particularly relates to a homopolymer POM composition, a preparation method thereof, and an application thereof. Background Art

[0002] As a highly crystalline engineering plastic, POM (polyoxymethylene resin) has good wear resistance, anti-creep characteristics, and excellent mechanical properties, and is widely used in the fields of industrial machinery, office equipment, household appliances, automobiles, etc.

[0003] Due to the high regularity of its molecular weight and high crystallinity, homopolymer POM is quite prominent in terms of strength, rigidity, self-lubrication, creep, fatigue, etc., and is widely used and difficult to be replaced by copolyoxymethylene. However, homopolymer POM is more likely to decompose, has a narrow processing window, poor thermal stability, and is prone to problems such as thermal decomposition, discoloration, and serious odor. Summary of the Invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention provides a homopolymer POM composition, a preparation method thereof, and an application thereof. The specific technical solutions are as follows:

[0005] A homopolymer POM composition, by weight, comprises the following components:

[0006]

[0007] Further, the melt mass flow rate of the homopolymer POM resin is 2-25 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 190 °C and 2.16 kg. If the melt mass flow rate of POM is low, it may cause too strong shear, a large amount of formaldehyde release, and obvious yellowing; but if the melt mass flow rate is too high, there are relatively many small molecules in itself, and the formaldehyde release amount is also high. The melt mass flow rate of the homopolymer POM resin can be 2.5 g / 10 min, 7 g / 10 min, 10 g / 10 min, 14 g / 10 min, 20 g / 10 min, 25 g / 10 min, etc.

[0008] Further, the melting point of the ethylene-vinyl alcohol copolymer is 160-190 °C. When the melting point of the ethylene-vinyl alcohol copolymer is 160-190 °C, the combination of the ethylene-vinyl alcohol copolymer and the POM molecular chain is closer during the processing, which is beneficial to inhibiting the degradation of POM and reducing the odor.

[0009] Further, the ethylene content of the ethylene-vinyl alcohol copolymer is between 20 mol%-40 mol%. When the ethylene content in the ethylene-vinyl alcohol copolymer is 20 mol%-40 mol%, it is beneficial to reduce the formaldehyde release.

[0010] Further, the number of carbon atoms of the alkyl diacid dihydrazide is 4 - 12, such as sebacic acid dihydrazide, succinic acid dihydrazide, dodecanedioic acid dihydrazide, etc. The number of carbon atoms in the alkyl diacid dihydrazide affects its melting point and reaction activity. The fewer the number of carbon atoms, the lower the melting point and the higher the reaction activity. However, it is not easy to process and is prone to precipitation to form mold scale. Controlling the number of carbon atoms of the alkyl diacid dihydrazide to be 4 - 12 is beneficial to reducing mold scale.

[0011] Further, the weight part of the ethylene - vinyl alcohol copolymer is preferably 0.28 - 0.6 part. By adding the alkyl diacid dihydrazide in the present invention, on the one hand, the alkyl diacid dihydrazide itself can play a role in reducing formaldehyde release. On the other hand, the alkyl diacid dihydrazide will react with the ethylene - vinyl alcohol copolymer to weaken the negative impacts on thermal stability and mold scale caused by a high addition amount of the ethylene - vinyl alcohol copolymer.

[0012] Further, the mass ratio of the alkyl diacid dihydrazide to the ethylene - vinyl alcohol copolymer is (2 - 6):(1 - 6).

[0013] Further, the main antioxidant is a hindered phenol antioxidant.

[0014] Preferably, the main antioxidant is tris(ethylene glycol) bis[β-(3 - tert - butyl - 4 - hydroxy - 5 - methylphenyl)propionate] or 3,9 - bis[1,1 - dimethyl - 2 - [(3 - tert - butyl - 4 - hydroxy - 5 - methylphenyl)propionyloxy]ethyl] - 2,4,8,10 - tetraoxaspiro[5.5]undecane.

[0015] Further, the co - antioxidant is tris(2,4 - di - tert - butylphenyl) phosphite and / or bis(2,6 - di - tert - butyl - 4 - methylphenyl)pentaerythritol diphosphite.

[0016] The present invention also provides a preparation method of the above - mentioned homopolymer POM composition, which comprises the following steps:

[0017] S1: Weigh each component according to the ratio and pre - mix them to obtain a premix;

[0018] S2: Put the premix obtained in step S1 into an extruder, carry out melt - blending and extrusion granulation to obtain the homopolymer POM composition.

[0019] Further, the extruder is a twin-screw extruder. The temperatures of the respective barrels of the twin-screw extruder from the feeding port to the head are as follows: 150°C - 170°C, 170°C - 180°C, 170°C - 190°C, 170°C - 200°C, 170°C - 200°C, 170°C - 200°C, 170°C - 200°C, 170°C - 200°C, 170°C - 200°C, 170°C - 200°C. The screw rotation speed is 200 - 300 revolutions per minute, the feeding rate is 50 - 200 kg / h, and the vacuum degree is (-0.1) - 0 MPa. More preferably, the lower the screw rotation speed within the range of 200 - 300 revolutions per minute, the better.

[0020] The present invention also provides the application of the above-mentioned homopolymer POM composition in the production of automobiles, household appliances, electronic and electrical products or daily necessities. For example, it is used to produce automotive interior products such as storage box slides, air outlet components, seat belt guide rings, etc.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The fundamental reason for formaldehyde release is the degradation of the molecular chain during the processing, and the formaldehyde generated by the degradation is oxidized to formic acid, which will in turn cause the material to turn yellow and the odor to increase. Diacylhydrazide can effectively reduce formaldehyde release and inhibit the formation of formic acid. At the same time, ethylene-vinyl alcohol copolymer also plays a role in reducing the degradation of the molecular chain and blocking formaldehyde. Through the combined action of alkyl diacid diacylhydrazide and ethylene-vinyl alcohol copolymer in the present invention, less addition amount of diacylhydrazide can achieve lower formaldehyde release, and at the same time, the color of the material is better. Specific Embodiments

[0023] The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] <Preparation of Examples and Comparative Examples>

[0025] The raw materials used in the embodiments and comparative examples of the present invention are all commercially available, but are not limited to these materials:

[0026] Homopolymer POM resin A: The melt mass flow rate is 14 g / 10 min, the grade is POM 500P, and it is purchased from DuPont;

[0027] Homopolymer POM resin B: The melt mass flow rate is 2 g / 10 min, the grade is POM 100P, and it is purchased from DuPont;

[0028] Homopolymer POM resin C: The melt mass flow rate is 25 g / 10 min, the grade is POM 900P, purchased from DuPont;

[0029] Alkyl diacid dihydrazide A: Sebacic dihydrazide, purchased from Wuhan Simac Bio;

[0030] Alkyl diacid dihydrazide B: Succinic dihydrazide, purchased from Hans Mac Bio;

[0031] Alkyl diacid dihydrazide C: Dodecanedioic dihydrazide, purchased from Hans Mac Bio;

[0032] Alkyl diacid dihydrazide D: Malonic dihydrazide, purchased from Hans Mac Bio;

[0033] Ethylene-vinyl alcohol copolymer A: The melting point is 164 °C, the ethylene content is 44 mol%, the grade is EVOH-44, purchased from Nippon Gohsei;

[0034] Ethylene-vinyl alcohol copolymer B: The melting point is 188 °C, the grade is EVOH-29, the ethylene content is 29 mol%, purchased from Nippon Gohsei;

[0035] Ethylene-vinyl alcohol copolymer C: The melting point is 200 °C, the grade is EVOH-25, the ethylene content is 25 mol%, purchased from Nippon Gohsei;

[0036] Ethylene-vinyl alcohol copolymer D: The melting point is 150 °C, the grade is EVOH-48, the ethylene content is 48 mol%, purchased from Nippon Gohsei;

[0037] Dicyandiamide: Purchased from Suzhou Senfeida Chemical Industry;

[0038] Primary antioxidant: Diethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], commercially available, the same commercially available product is used for parallel experiments;

[0039] Secondary antioxidant: Tris(2,4-di-tert-butylphenyl) phosphite, commercially available, the same commercially available product is used for parallel experiments.

[0040] The preparation methods of the examples and comparative examples of the present invention are as follows:

[0041] S1: According to the ratios in Table 1 and Table 3, weigh each component and premix them to obtain a premix;

[0042] S2: Put the premix obtained in step S1 into a twin-screw extruder, carry out melt blending and extrusion granulation to obtain a homopolymer POM composition.

[0043] The temperatures of each barrel of the twin-screw extruder from the feeding port to the head are respectively: 160°C, 175°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 190°C. The screw speed is 200 revolutions per minute, the feeding rate is 100 kg / h, and the vacuum degree is (-0.1) MPa.

[0044] Examples 8-13 have the same formula as Example 3, with the only difference being the screw speed in the preparation method. The screw speeds of Examples 8-13 are respectively 220 revolutions per minute, 250 revolutions per minute, 280 revolutions per minute, 300 revolutions per minute, 150 revolutions per minute, and 400 revolutions per minute.

[0045] <Test standard>

[0046] The performance test standards for each example and comparative example of the present invention are as follows:

[0047] Mass retention rate: The thermal stability of the material is evaluated by the mass retention rate of isothermal thermogravimetry under air conditions. The sample is heated to 230°C at a rate of 20°C / min under air conditions and then held at 230°C for 1 hour. The higher the mass retention rate, the better the thermal stability.

[0048] Formaldehyde release amount: It is evaluated according to standard VDA275. The lower the formaldehyde release amount, the better the thermal stability.

[0049] Yellow index: The extruded particles are injection molded into color plates at 200°C, and the yellow index is tested and calculated by the method of GB / T2409-1980. The smaller the yellow index, the better the effect.

[0050] Mold fouling: The sample is continuously injection molded 200 molds in an injection molding machine at 230°C, and the weight of the collected mold fouling is weighed and the mold fouling situation on the mold surface is observed.

[0051] Table 1. Formulas of Examples 1-7 (parts by weight)

[0052]

[0053] Table 2. Formulas of Examples 8-10 (parts by weight)

[0054] Example 8 9 10 Homopolymer POM resin A 100 100 100 Alkyl diacid dihydrazide A 0.3 0.3 0.3 Ethylene-vinyl alcohol copolymer B 0.2 Ethylene-vinyl alcohol copolymer C 0.2 Ethylene-vinyl alcohol copolymer D 0.2 Primary antioxidant 0.2 0.2 0.2 Secondary antioxidant 0.2 0.2 0.2

[0055] Table 3. Performance test results of Examples 1-10

[0056]

[0057]

[0058] Table 4. Formulas of Comparative Examples 1-7 (parts by weight)

[0059] Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Homopolymer POM resin A 100 100 100 100 100 100 100 Alkyl diacid dihydrazide A 0 0.3 0.1 1 0.3 0.3 Dicyandiamide 0.3 Ethylene-vinyl alcohol copolymer A 0.2 0 0.2 0.2 0.05 0.6 0.2 Primary antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Secondary antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2

[0060] Table 5. Performance test results of Comparative Examples 1-7

[0061] Test item Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Mass retention rate (%) 97.54 97.66 97.23 97.43 97.24 97.88 97.45 Formaldehyde release amount (ppm) 8.65 4.53 7.56 1.32 4.93 4.03 4.66 Yellow index 2.45 2.74 2.34 2.84 2.56 3.13 3.02 Mold fouling (mg) 0.13 0.072 0.066 0.35 0.16 0.24 0.28

[0062] The mass retention rate of the homopolymer POM composition provided by the present invention is 97.92-98.86%, the formaldehyde release amount is lower than 2.16 ppm, the yellowness index is lower than 2.15, and the mold scale is lower than 0.041 mg, having good thermal stability.

[0063] Comparing Comparative Example 1 with Example 3, no alkyl diacid dihydrazide was added in Comparative Example 1, resulting in a decrease in the mass retention rate of the material, a significant increase in the formaldehyde release amount, and an increase in the degree of yellowing.

[0064] Comparing Comparative Example 2 with Example 3, no ethylene-vinyl alcohol copolymer was added in Comparative Example 2, and the mass retention rate of Comparative Example 2 decreased, the formaldehyde release amount increased, and the yellowness index increased.

[0065] Comparing Comparative Examples 3 and 4 with Example 3, whether the amount of alkyl diacid dihydrazide is too much or too little, it will cause the mass retention rate of the material to decrease, the formaldehyde release amount to increase, and the yellowness index to increase.

[0066] Comparing Comparative Examples 5 and 6 with Example 3, when the amount of ethylene-vinyl alcohol copolymer exceeds the range, it will also have a negative impact on the mass retention rate, formaldehyde release amount and yellowness index of the material.

[0067] Comparing Comparative Example 7 with Example 3, the only difference is that dicyandiamide is used in Comparative Example 7, but the mass retention rate of Comparative Example 7 is lower than that of Example 3, and the formaldehyde release amount, yellowness index and mold scale all increase.

[0068] 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 homopolymer POM composition, characterized in that, By weight parts, it comprises the following components: The number of carbon atoms of the alkyl diacid dihydrazide is 4 - 12.

2. The homopolymer POM composition according to claim 1, characterized in that, The melt mass flow rate of the homopolymer POM resin is 2 - 25 g / 10 min.

3. The homopolymer POM composition according to claim 1, characterized in that, The melting point of the ethylene-vinyl alcohol copolymer is 160 - 190 °C.

4. The homopolymer POM composition according to claim 1, characterized in that, The primary antioxidant is a hindered phenol antioxidant.

5. The homopolymer POM composition according to claim 1, characterized in that The primary antioxidant is tris(ethylene glycol) bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] or 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.

6. A method for preparing a homopolymer POM composition according to any one of claims 1-5, characterized in that, It comprises the following steps: S1: Weigh each component according to the ratio, and after premixing, obtain a premix; S2: Put the premix of step S1 into an extruder, carry out melt blending and extrusion granulation to obtain the homopolymer POM composition.

7. The preparation method of the homopolymer POM composition according to claim 6, characterized in that, In step S2, the screw rotation speed of the extruder is 200 - 300 revolutions per minute.

8. The application of the homopolymer POM composition according to any one of claims 1 - 5 in the production of automobiles, electronic and electrical products or daily necessities.

9. The application according to claim 8, wherein The application of the homopolymer POM composition in the production of household appliances.

Images