Polyformaldehyde composite material and preparation method thereof

Abstract

The invention discloses a polyformaldehyde composite material and a preparation method thereof, the polyformaldehyde composite material comprises a compound component, the compound component is formed by compounding compound raw materials, and the compound raw materials comprise, by weight, 60-90 parts of polyformaldehyde resin, 1-20 parts of polyamide resin, 1-30 parts of porous graphite and 1-30 parts of hollow microspheres. According to the invention, by compounding the appropriate compound raw materials, the prepared polyformaldehyde composite material can absorb the noise generated in the friction and impact process, and has both noise reduction and wear resistance.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and in particular to a polyoxymethylene composite material and a preparation method thereof. Background Art

[0002] Polyoxymethylene (POM) has a rigidity and hardness close to that of metal, good fatigue resistance and chemical resistance, and similar to polyamide materials, good self-lubricating properties and wear resistance. These excellent comprehensive properties make POM one of the five general engineering plastics. The existing technology points out that by compounding with appropriate additives, the wear resistance of POM is better, but the harsh use environment not only requires wear resistance of POM, but also requires that the noise during the friction process is as low as possible to avoid noise pollution. Therefore, a composite material with both noise reduction and wear resistance is urgently needed. Summary of the invention

[0003] In view of this, the present application provides a polyformaldehyde composite material and a preparation method thereof. The polyformaldehyde composite material contains a compound component, which is the main component of the polyformaldehyde composite material. It can be obtained by compounding a variety of compound raw materials. The present application selects suitable compound raw materials for compounding so that the various compound raw materials can cooperate in the compounding process, so that the prepared polyformaldehyde composite material can absorb the noise generated during the friction and collision between materials, and has both noise reduction and wear resistance properties.

[0004] In the first aspect, the present application provides a polyoxymethylene composite material, the polyoxymethylene composite material includes a compound component, the compound component is compounded from compound raw materials, the compound raw materials include by weight: 60-90 parts of polyoxymethylene resin, 1-20 parts of polyamide resin, 1-30 parts of porous graphite and 1-30 parts of hollow microspheres. Preferably, the compound raw materials include by weight: 80-90 parts of polyoxymethylene resin, 5-15 parts of polyamide resin, 10-20 parts of porous graphite and 10-20 parts of hollow microspheres.

[0005] The present application mixes appropriate weight portions of polyamide resin with an appropriate amount of polyformaldehyde resin so that the polyamide resin can be dispersed in the polyformaldehyde resin in a spherical phase state. After crystallization, the polyamide resin and the polyformaldehyde resin are phase separated so that there is a gap at the phase interface. At the same time, the composite raw materials of the present application also include an appropriate amount of porous graphite and an appropriate amount of hollow microspheres. Through the coordinated cooperation of the porous graphite, the hollow microspheres and the above-mentioned phase interface gaps, the prepared polyformaldehyde composite material can absorb its friction (including friction between its own materials and friction between it and other materials) and noise during impact.

[0006] In some embodiments, the melt index of the polyformaldehyde resin is 10 to 50 g / 10 min, preferably, the melt index of the polyformaldehyde resin is 10 to 30 g / 10 min. Wherein, the melt index is obtained by testing under 2.16 kg and 190 ° C. The viscosity of the polyamide resin is 2.3 to 2.9 cP, preferably, the viscosity of the polyamide resin is 2.4 to 2.8 cP, and the crystallinity of the polyamide resin is greater than 15%. When the melt index of the polyformaldehyde resin is within the above range and the viscosity and crystallinity of the polyamide resin are appropriate, it is more conducive to the formation of a suitable polymer alloy phase morphology, thereby generating a phase interface gap that can better cooperate with the porous graphite and hollow microspheres, which is more conducive to the improvement of the noise reduction effect.

[0007] In some embodiments, the D50 value of the porous graphite is 10 μm to 100 μm, and the specific surface area of ​​the porous graphite is less than 30 m 2 Preferably, the D50 value of the porous graphite is 20 μm to 30 μm, and the specific surface area of ​​the porous graphite is denoted as S, which satisfies: 25m 2 / g≤S<30m 2 The porous graphite within the above parameter range is more conducive to compounding with compound raw materials and hollow microspheres, so that the prepared polyoxymethylene composite material has better sound absorption and noise reduction effect and a low friction coefficient.

[0008] In some embodiments, the D50 value of the hollow microspheres is 10 μm to 100 μm, and the density of the hollow microspheres is less than 0.6 g / cm 3 Preferably, the D50 value of the hollow microspheres is 10 μm to 15 μm, and the density of the hollow microspheres is 0.45 to 0.5 g / cm 3 The hollow microspheres include hollow glass microspheres or hollow ceramic microspheres. The hollow microspheres within the above parameter range can be better compounded with the compounding raw materials and porous graphite to enhance the sound absorption and noise reduction effect of the polyoxymethylene composite material.

[0009] In some embodiments, the polyoxymethylene composite material further comprises other components, the other components comprising an elastomer, an antioxidant A, an antioxidant B and a lubricant, the elastomer being selected from at least one of polyurethane elastomer, nitrile rubber, silicone rubber or ethylene propylene rubber, the antioxidant A comprising a hindered phenol antioxidant, the antioxidant B comprising a phosphite antioxidant, and the lubricant being selected from at least one of a polyol ester lubricant, a silicone lubricant or a stearic acid lubricant. Suitable elastomers can regulate the toughness of the system, so that the POM matrix has excellent rigidity-toughness balance performance and is not easy to break or crack during use.

[0010] In some embodiments, the hindered phenol antioxidant is selected from at least one of antioxidant 1098, antioxidant 1010, and antioxidant 1076.

[0011] In some embodiments, the phosphite antioxidant is selected from at least one of antioxidant 168 and antioxidant PEP36.

[0012] In some embodiments, the friction coefficient of the polyoxymethylene composite material is less than 0.2, the sound of the polyoxymethylene composite material falling vertically from a height of 10 cm to a glass plate is less than 40 decibels, and the ISO notched impact strength of the polyoxymethylene composite material is greater than 8 kJ / m 2 Preferably, the sound of the polyoxymethylene composite material falling vertically from a height of 10 cm onto a glass plate is no more than 35 decibels, and the ISO notched impact strength of the polyoxymethylene composite material is 8.5 kJ / m 2 above.

[0013] In a second aspect, the present application provides a method for preparing the above-mentioned polyoxymethylene composite material, the preparation method comprising at least the following steps:

[0014] (1) mixing polyoxymethylene resin, polyamide resin, porous graphite, hollow microspheres and other components uniformly according to a weight ratio to obtain a premix;

[0015] (2) blending the premix in step (1) to obtain a blend, wherein the blending comprises:

[0016] First blending stage: stirring at 600-1000 rpm for 1-10 min;

[0017] Second blending stage: stirring at 100-300 rpm for 1-5 min;

[0018] The third blending stage: releasing the uniformly mixed blend at 50-100 rpm;

[0019] (3) Extruding the blended material in step (2) at a rotation speed of 200 to 500 rpm and a temperature of 180 to 260° C.

[0020] The beneficial effects brought about by the technical solutions provided in some embodiments of the present application include at least: in the present application, polyformaldehyde resin and polyamide resin of suitable types and appropriate weight ratios are used for blending treatment to produce gaps at the phase interface after crystallization. At the same time, the present application further adds appropriate weight portions of porous graphite and appropriate weight portions of hollow microspheres to the compound raw materials for coordination, so that the porous graphite, hollow microspheres and the gaps produced at the above-mentioned phase interfaces can interact with each other, thereby achieving the polyformaldehyde composite material being able to absorb the noise generated during friction and impact, while taking into account wear-resistant properties. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0022] Polyoxymethylene composite materials

[0023] The polyoxymethylene composite material comprises a compound component, which is prepared by compounding compound raw materials. The compound raw materials comprise, by weight: 60-90 parts of polyoxymethylene resin, 1-20 parts of polyamide resin, 1-30 parts of porous graphite and 1-30 parts of hollow microspheres.

[0024] Illustratively, the composite raw materials include, by weight: 70 to 90 parts of polyoxymethylene resin, 3 to 18 parts of polyamide resin, 5 to 25 parts of porous graphite, and 5 to 25 parts of hollow microspheres.

[0025] Illustratively, the composite raw materials include, by weight: 80 to 90 parts of polyoxymethylene resin, 5 to 15 parts of polyamide resin, 10 to 20 parts of porous graphite and 10 to 20 parts of hollow microspheres.

[0026] Illustratively, the composite raw materials include, by weight: 80 to 85 parts of polyoxymethylene resin, 10 to 15 parts of polyamide resin, 10 to 15 parts of porous graphite, and 15 to 20 parts of hollow microspheres.

[0027] In some embodiments, the melt index of the polyoxymethylene resin is 10 to 50 g / 10 min. Preferably, the melt index of the polyoxymethylene resin is 10 to 30 g / 10 min.

[0028] Exemplarily, the melt index of the polyoxymethylene resin is 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, or a range consisting of any two of the above values.

[0029] In some embodiments, the viscosity of the polyamide resin is 2.3 to 2.9 cP. Preferably, the viscosity of the polyamide resin is 2.4 to 2.8 cP.

[0030] Illustratively, the viscosity of the polyamide resin is 2.3 cP, 2.4 cP, 2.5 cP, 2.6 cP, 2.7 cP, 2.8 cP, 2.9 cP or a range consisting of any two of the above values.

[0031] In some embodiments, the crystallinity of the polyamide resin is greater than 15%. Preferably, the crystallinity of the polyamide resin is 15-30%.

[0032] Illustratively, the crystallinity of the polyamide resin is 15%, 18%, 20%, 23%, 25%, 28%, 30% or a range consisting of any two of the above values.

[0033] In some embodiments, the D50 value of the porous graphite is 10 μm to 100 μm. Preferably, the D50 value of the porous graphite is 20 μm to 30 μm.

[0034] Exemplarily, the D50 value of the porous graphite is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range consisting of any two of the above values.

[0035] In some embodiments, the specific surface area of ​​the porous graphite is less than 30 m 2 / g. Preferably, the specific surface area of ​​the porous graphite is denoted as S, satisfying: 25m 2 / g≤S<30m 2 / g.

[0036] Exemplarily, the specific surface area of ​​the porous graphite is 0.5 m 2 / g, 5m 2 / g, 8m 2 / g, 10m 2 / g, 15m 2 / g, 20m 2 / g, 25m 2 / g, 28m 2 / g, 29m 2 / g or a range consisting of any two of the above values.

[0037] In some embodiments, the D50 value of the hollow microspheres is 10 μm to 100 μm. Preferably, the D50 value of the hollow microspheres is 10 μm to 15 μm.

[0038] Illustratively, the D50 value of the hollow microbeads is 10 μm, 13 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range consisting of any two of the above values.

[0039] In some embodiments, the density of the hollow microspheres is less than 0.6 g / cm 3 Preferably, the density of the hollow microspheres is 0.45 to 0.5 g / cm 3 .

[0040] For example, the density of the hollow microspheres is 0.01 g / cm 3 , 0.05g / cm 3 , 0.1g / cm 3 , 0.2g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3 , 0.45g / cm 3 , 0.5g / cm 3 , 0.55g / cm 3 Or a range consisting of any two of the above values.

[0041] In some embodiments, the polyoxymethylene composite material also includes other components, including an elastomer, an antioxidant A, an antioxidant B and a lubricant, the elastomer is selected from at least one of polyurethane elastomer, nitrile rubber, silicone rubber or EPDM rubber, the antioxidant A includes a hindered phenol antioxidant, the antioxidant B includes a phosphite antioxidant, and the lubricant is selected from at least one of a polyol ester lubricant, a silicone lubricant or a stearic acid lubricant.

[0042] In some embodiments, the hindered phenol antioxidant is selected from at least one of antioxidant 1098, antioxidant 1010, and antioxidant 1076.

[0043] In some embodiments, the phosphite antioxidant is selected from at least one of antioxidant 168 and antioxidant PEP36.

[0044] In some embodiments, the friction coefficient of the polyoxymethylene composite material is less than 0.2, the sound of the polyoxymethylene composite material falling vertically from a height of 10 cm to a glass plate is less than 40 decibels, and the ISO notched impact strength of the polyoxymethylene composite material is greater than 8 kJ / m 2 .

[0045] Preparation method of polyoxymethylene composite material

[0046] The preparation method comprises at least the following steps:

[0047] (1) mixing polyoxymethylene resin, polyamide resin, porous graphite, hollow microspheres and other components uniformly according to a weight ratio to obtain a premix;

[0048]

[0049]

[0050] (2) blending the premix in step (1) to obtain a blend, wherein the blending comprises:

[0051] First blending stage: stirring at 600-1000 rpm for 1-10 min;

[0052] Second blending stage: stirring at 100-300 rpm for 1-5 min;

[0053] The third blending stage: releasing the uniformly mixed blend at 50-100 rpm;

[0054] (3) Extruding the blended material in step (2) at a rotation speed of 200 to 500 rpm and a temperature of 180 to 260° C. Too low a rotation speed is not conducive to material mixing, too high a rotation speed will cause resin degradation, and too low a processing temperature will cause the polymer to fail to plasticize, and too high a processing temperature will cause the polymer to degrade.

[0055] Example

[0056] The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0057] Example 1

[0058] A polyoxymethylene composite material comprises the following raw materials in parts by weight: 70 parts of homopolymer POM (polyoxymethylene resin), 10 parts of polyamide PA6 (polyamide resin), 10 parts of polyurethane elastomer, 10 parts of porous graphite, 10 parts of hollow glass microspheres, 0.1 parts of antioxidant 1076, 0.2 parts of antioxidant 168, and 0.5 parts of lubricant stearate PETS. Among them, the melt index of homopolymer POM is 15g / 10min (190°C, 2.16kg), the viscosity of polyamide PA6 is 2.5cP and its crystallinity is 17%, the D50 value of porous graphite is 20μm and its specific surface area is 10m 2 / g, the D50 value of hollow microspheres is 10 μm and its density is 0.45 g / cm 3 .

[0059] Compared with Example 1, Examples 2 to 4 are different in that the weight fractions of each raw material are further adjusted in Examples 2 to 4, as shown in Table 1 for details, and the rest are the same as Example 1.

[0060] Compared with Example 4, the difference between Comparative Example 1-1 and Example 4 is that Comparative Example 1-1 further increases the proportion of polyamide resin, and the rest is the same as Example 4.

[0061] Compared with Example 1, the differences between Comparative Examples 1 to 4, Comparative Example 3-1 and Comparative Example 4-1 are that Comparative Examples 1 to 4, Comparative Example 3-1 and Comparative Example 4-1 respectively use the single variable method to discuss the necessity of the existence of each compound raw material and the effect of the appropriate amount of compound raw materials on noise reduction and wear resistance.

[0062] Preparation method:

[0063] (1) according to a predetermined raw material ratio, homopolymer POM, polyamide PA6, polyurethane elastomer, porous graphite, hollow glass microspheres, antioxidant 1076, antioxidant 168 and stearate PETS are sequentially added into a high-speed mixer and mixed uniformly to prepare a premix;

[0064] (2) blending the premix to obtain a blend, wherein the blending comprises:

[0065] First blending stage: stirring at 600 rpm for 3 min;

[0066] Second blending stage: stirring at 100 rpm for 2 min;

[0067] The third blending stage: releasing the uniformly mixed blend at 50 rpm;

[0068] (3) The blended material in step (2) is extruded through an extruder (model: Ruiya 35 extruder) at a speed of 300 rpm. The temperatures of the extruder from the feed port to the die are as follows:

[0069] 100℃ (feeding port temperature) -230℃-230℃-230℃ (plasticizing section zone 1 temperature) -220℃-220℃-220℃ (plasticizing section zone 2 temperature) -210℃-210℃ (extrusion section temperature) -220℃ (die head temperature).

[0070] Noise reduction test method: The prepared sample (polyoxymethylene composite material) was dropped vertically from a height of 10 cm onto a float glass plate (3 mm thick, 20*20 cm long and wide), and recorded using a decibel tester (model: Delixi Electric Decibel Meter DSM D1).

[0071] Table 1

[0072]

[0073] It can be seen from Table 1 that the polyoxymethylene composite materials prepared in Examples 1 to 4 have excellent comprehensive performance, and the friction coefficient is less than 0.2, which has low friction and wear resistance. The sound produced by the impact when it falls from a height of 10 cm onto a glass plate is weak, which is less than 40 decibels. It can be seen that the polyoxymethylene composite materials have sound absorption and noise reduction effects. At the same time, the ISO notched impact strength of the materials is greater than 8 kJ / m 2 , that is, it also has excellent rigidity-toughness balance performance. In particular, the sound of the polyoxymethylene composite material prepared in Example 4 falling from a height of 10 cm onto a glass plate is only 34 decibels, and its ISO notched impact strength is as high as 9.7 kJ / m 2 .

[0074] Comparison of Example 1-1 and Example 1 with Example 1 shows that although the friction coefficients of Comparison Example 1-1 and Comparison Example 1 are less than 0.2, the impact sound during the drop test is higher than 40 decibels, especially Comparison Example 1, because no polyamide resin is added to the compound raw materials, the impact sound during the drop test is as high as 48 decibels. However, since the proportion of polyamide resin in Comparison Example 1-1 is too high, it is not conducive to its dispersion in the POM system in a spherical phase state. At this time, the polyamide resin is more inclined to be distributed in a strip phase state, which is not conducive to the formation of a suitable gap, nor is it conducive to adaptation with porous graphite and hollow microspheres. The wear resistance and noise reduction performance of the obtained polyoxymethylene composite material are not good.

[0075] Compared with Example 1, in Example 2, the ISO impact strength of Example 2 without adding polyurethane elastomer is only 3.2 kJ / m 2 , indicating that the elastomer can better improve the toughness of the system and achieve a balance between rigidity and toughness.

[0076] Comparison between Example 3 and Example 3-1 shows that when porous graphite is not added to the composite component (Comparative Example 3), the noise reduction performance of the prepared polyoxymethylene composite material is poor, and the impact sound during the drop test is as high as 43 decibels. When excessive porous graphite is added (Comparative Example 3-1), the impact resistance of the material is poor, and the ISO notched impact strength is only 4.3 kJ / m 2 , which is not conducive to improving the comprehensive performance of materials.

[0077] Comparison between Example 4 and Example 4-1 shows that when hollow microspheres are not added to the composite component (Comparative Example 4), the noise reduction performance of the prepared polyoxymethylene composite material is poor, and the impact sound during the drop test is as high as 45 decibels. When an excessive amount of hollow microspheres is added (Comparative Example 4-1), the ISO notched impact strength is only 3.5 kJ / m 2 , which is not conducive to improving the comprehensive performance of materials.

[0078] Table 2 discusses the influence of the selection of various parameters of the compound raw materials on the noise reduction effect. Table 2 is based on further improvement of Example 2. The selection of the compound raw materials of each example in Table 2 can be referred to Example 2. The specific parameters are shown in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] It can be seen from Table 2 that further adjusting the melt index of the polyoxymethylene resin and various parameters of the porous graphite and the hollow microspheres within a suitable range can better improve the noise reduction performance of the polyoxymethylene composite material.

[0083] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A polyoxymethylene composite material, characterized in that: The polyoxymethylene composite material comprises a compound component, and the compound component is prepared by compounding compound raw materials; The composite raw materials include, by weight: 60 to 90 parts of polyoxymethylene resin, 1 to 20 parts of polyamide resin, 1 to 30 parts of porous graphite and 1 to 30 parts of hollow microspheres.

2. The polyoxymethylene composite material according to claim 1, characterized in that: The composite raw materials include, by weight: 80 to 90 parts of polyoxymethylene resin, 5 to 15 parts of polyamide resin, 10 to 20 parts of porous graphite and 10 to 20 parts of hollow microspheres.

3. The polyoxymethylene composite material according to claim 1, characterized in that: At least one of the following conditions is met: Condition I: The melt index of the polyoxymethylene resin is 10 g / 10 min to 50 g / 10 min; Condition II: the viscosity of the polyamide resin is 2.3 cP to 2.9 cP; Condition III: The crystallinity of the polyamide resin is greater than 15%.

4. The polyoxymethylene composite material according to claim 1, characterized in that: The D50 value of the porous graphite is 10 μm to 100 μm; The specific surface area of ​​the porous graphite is less than 30 m 2 / g.

5. The polyoxymethylene composite material according to claim 4, characterized in that: The D50 value of the porous graphite is 20 μm to 30 μm; The specific surface area of ​​the porous graphite is denoted as S, which satisfies: 25m 2 / g≤S<30m 2 / g.

6. The polyoxymethylene composite material according to claim 1, characterized in that: The D50 value of the hollow microspheres is 10 μm to 100 μm; The density of the hollow microspheres is less than 0.6 g / cm 3 .

7. The polyoxymethylene composite material according to claim 6, characterized in that: The D50 value of the hollow microspheres is 10 μm to 15 μm; The density of the hollow microspheres is 0.45 g / cm 3 Up to 0.5g / cm 3 .

8. The polyoxymethylene composite material according to claim 1, characterized in that: The polyoxymethylene composite material also includes other components; The other components include elastomer, antioxidant A, antioxidant B and lubricant; The elastomer is selected from at least one of polyurethane elastomer, nitrile rubber, silicone rubber or ethylene propylene rubber; The antioxidant A comprises a hindered phenol antioxidant; The antioxidant B includes a phosphite antioxidant; The lubricant is selected from at least one of polyol ester lubricants, silicone lubricants or stearic acid lubricants.

9. The polyoxymethylene composite material according to claim 1, characterized in that: The friction coefficient of the polyoxymethylene composite material is less than 0.2; The sound of the polyoxymethylene composite material falling vertically from a height of 10 cm onto a glass plate is less than 40 decibels; The polyoxymethylene composite material has an ISO notched impact strength greater than 8 kJ / m 2 .

10. The method for preparing the polyoxymethylene composite material according to any one of claims 1 to 9, characterized in that: The preparation method comprises at least the following steps: (1) mixing polyoxymethylene resin, polyamide resin, porous graphite, hollow microspheres and other components uniformly according to a weight ratio to obtain a premix; (2) blending the premix in step (1) to obtain a blend, wherein the blending comprises: First blending stage: stirring at 600 rpm to 1000 rpm for 1 min to 10 min; Second blending stage: stirring at 100 rpm to 300 rpm for 1 min to 5 min; The third blending stage: releasing the uniformly mixed blend at 50 rpm to 100 rpm; (3) Extruding the blended material in step (2) at a rotation speed of 200 rpm to 500 rpm and a temperature of 180° C. to 260° C.

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