A high-strength and impact-resistant PP composite material and its preparation method

Abstract

The present invention relates to the field of material technology, and discloses a high-strength anti-stamping PP composite material and a preparation method thereof. This composite material uses polypropylene as the matrix material and modifiers, compatibilizers, etc. as auxiliary materials, and is made by a process of mixing and extrusion granulation. The modifier is sepiolite fiber with nano-titanium dioxide loaded on its surface. On the one hand, the grafting agent has good compatibility with the polypropylene matrix, which can avoid the negative impact caused by poor compatibility between the modifier and the polypropylene matrix. On the other hand, nano-titanium dioxide can relatively slip on the surface of the sepiolite fiber to produce a micro ball bearing effect, thereby effectively improving the wear resistance of the polypropylene composite material. Moreover, due to the loading of nano-titanium dioxide, a micro three-dimensional structure is formed on the surface of the sepiolite fiber, and this structure can be stuck in the polypropylene matrix, enabling the sepiolite fiber to efficiently play the role of strengthening and modification and improving the strength of the polypropylene composite material.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and particularly relates to a high-strength and anti-stamping PP composite material and a preparation method thereof. Background Art

[0002] In modern stationery manufacturing, composite materials are highly favored due to their unique performance advantages. Stationery, as an indispensable tool for daily study and work, its quality, durability, and feel directly affect the user experience and efficiency. Polypropylene (abbreviated as PP) is a colorless, odorless, and non-toxic thermoplastic plastic, with characteristics such as low density, light weight, chemical corrosion resistance, good insulation performance, and convenient processing. Due to its excellent physical properties, chemical stability, and relatively low cost, it has gradually become one of the indispensable composite materials in stationery manufacturing, such as pen barrels, stationery boxes, file folders, file folder clasps, etc.

[0003] Stationery products are not only practical tools but also a reflection of personal taste and style. Therefore, durability and aesthetics are one of the key concerns of consumers. Although polypropylene has relatively excellent comprehensive properties, its strength performance is slightly poor and its wear resistance is not good. In the case of long-term writing or accidental dropping, it is difficult to maintain its integrity and cannot avoid a large number of scratches and wear caused by friction, resulting in a decline in the aesthetics of the product. Therefore, how to enhance and modify polypropylene to meet the requirements of high-end stationery has become a research hotspot.

[0004] The invention patent with the publication number CN114507400B discloses a modified glass fiber reinforced polypropylene composition and a preparation method thereof. By using oxidized polyethylene wax to modify medium-alkali glass fiber, modified medium-alkali glass fiber is prepared. As an additive, it can effectively enhance the strength of polypropylene. Therefore, using fiber as an additive has a positive effect on improving the mechanical strength of polypropylene. However, using fiber alone as an additive cannot produce a good modification effect on the wear resistance of polypropylene. Based on this, the present invention provides a high-strength and anti-stamping PP composite material, which can be directly used to manufacture high-end stationery products. Summary of the Invention

[0005] In order to solve the problems mentioned in the background art, the purpose of the present invention is to provide a high-strength and anti-stamping PP composite material and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a high-strength and anti-stamping PP composite material, wherein the PP composite material is made of raw materials including the following parts by weight:

[0008]

[0009] The preparation method comprises the following steps:

[0010] First step: Weigh each raw material in sequence according to parts by weight and set aside for use;

[0011] Second step: Add polypropylene, modifier, compatibilizer, antioxidant, and lubricant into a stirring kettle, control the rotation speed at 1000 - 2000 r / min, the temperature at 100 - 120 °C, mechanically stir and mix for 30 - 60 min, then cool down and discharge to form the pre-mixed material;

[0012] Third step: Feed the pre-mixed material into a twin-screw extruder, and through the melting extrusion granulation process, the PP composite material can be obtained.

[0013] As a further scheme of the present invention, the preparation method of the modifier comprises the following steps:

[0014] Step one: Disperse sepiolite fiber in toluene to form a sepiolite fiber dispersion liquid, denoted as dispersion liquid one; Disperse nano-titanium dioxide in toluene to form a nano-titanium dioxide dispersion liquid, denoted as dispersion liquid two;

[0015] Step two: Add a grafting agent to dispersion liquid one. After adding, continue to add a tin metal catalyst and stir evenly. Then raise the temperature to 70 - 80 °C, keep the temperature for stirring for 2 - 4 h, then lower the temperature to 40 - 50 °C, and then add dispersion liquid two. After adding, further raise the temperature to 80 - 90 °C, continue to keep the temperature for 6 - 9 h, then centrifuge to separate out the solid material, and through washing and vacuum drying treatment, the modifier can be obtained.

[0016] As a further scheme of the present invention, in step one, the mass fraction of dispersion liquid one is 20 - 30%; the mass fraction of dispersion liquid two is 10 - 15%.

[0017] As a further scheme of the present invention, in step two, the preparation method of the grafting agent is as follows:

[0018] Mix hydroxyl-terminated nitrile rubber with tetrahydrofuran, stir evenly, and under ice bath conditions, add benzoyl chloride modifier and pyridine to the obtained homogeneous liquid material. After adding, remove from the ice bath and stir at room temperature for 6 - 9 h, then evaporate to remove the solvent and separate out the material to obtain the grafting agent.

[0019] As a further scheme of the present invention, the benzoyl chloride modifier is 4-isocyanatobenzoyl chloride or 3-isocyanatoxybenzoyl chloride.

[0020] As a further scheme of the present invention, the molar ratio of the hydroxyl-terminated nitrile rubber to the benzoyl chloride modifier is 1:2.

[0021] As a further aspect of the present invention, in step two, the tin metal catalyst is any one of stannous octoate, dibutyltin diacetate or dibutyltin dilaurate.

[0022] As a further aspect of the present invention, in step two, the volume ratio of the first dispersion liquid to the second dispersion liquid is 1:0.2 - 0.4.

[0023] Specifically, first, using hydroxyl - terminated nitrile rubber and benzoyl chloride modifier as reactants, by controlling the molar ratio between the two, a nitrile rubber derivative with highly active isocyanate groups at the ends, that is, a grafting agent, is prepared. Then, under the action of the tin metal catalyst, the isocyanate group at one end of the grafting agent structure can undergo a grafting reaction with the hydroxyl groups on the surface of sepiolite fibers, and the isocyanate group at the other end can undergo a grafting reaction with nano - titanium dioxide. It is equivalent to using the grafting agent as a connecting substance to achieve the load connection of nano - titanium dioxide and sepiolite fibers, and a modifier is prepared.

[0024] As a further aspect of the present invention, the compatibilizer is maleic anhydride - grafted polyethylene or maleic anhydride - grafted polypropylene; the antioxidant is a phosphite antioxidant; the lubricant is any one of paraffin wax, polyethylene wax or stearic acid.

[0025] A high - strength anti - stamping PP composite material is prepared by the above - mentioned preparation method.

[0026] Advantages of the present invention:

[0027] In the present invention, by preparing sepiolite fibers loaded with nano - titanium dioxide as a modifier to modify polypropylene. On the one hand, the grafting agent that realizes the load connection between each other is a nitrile rubber derivative, which has good compatibility with the polypropylene matrix. Therefore, it can avoid the negative impact caused by poor compatibility between the modifier and the polypropylene matrix. On the other hand, since nitrile rubber is an oily polymer substance, it can promote the relative slip of nano - titanium dioxide on the surface of sepiolite fibers, generating a micro - ball bearing effect, thereby effectively improving the wear resistance of the polypropylene composite material. Moreover, due to the loading of nano - titanium dioxide, a micro three - dimensional structure is formed on the surface of sepiolite fibers, and this micro three - dimensional structure can firmly lock in the polypropylene matrix, forming a firm snap - type structure, so that sepiolite fibers can efficiently play the role of strengthening and modification, and improve the strength of the polypropylene composite material.

[0028] Of course, it is not necessary for any product implementing the present invention to achieve all the above - mentioned advantages simultaneously. Description of the drawings

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 Scanning electron micrographs of sepiolite fiber and modifier, where (A) is sepiolite fiber and (B) is the modifier. Detailed implementation manners

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0032] Preparation examples

[0033] The preparation method of the modifier includes the following steps:

[0034] Step 1: Disperse sepiolite fiber in toluene to form a sepiolite fiber dispersion with a mass fraction of 25%, denoted as dispersion one; disperse nano-titanium dioxide in toluene to form a nano-titanium dioxide dispersion with a mass fraction of 10%, denoted as dispersion two.

[0035] Step 2: Mix 1.5 g of hydroxyl-terminated nitrile rubber with a number average molecular weight of 3500 with tetrahydrofuran, stir evenly, and then, under ice bath conditions, add 0.16 g of 3-isocyanatobenzoyl chloride and 0.2 g of pyridine to the obtained homogeneous liquid material. After adding, remove the ice bath and stir at room temperature for 8 h, then evaporate to remove the solvent and separate the material to obtain the grafting agent.

[0036] Step 3: Add the grafting agent to 20 mL of dispersion one. After adding, continue to add 0.1 g of dibutyltin dilaurate, stir evenly, then raise the temperature to 75 °C, keep stirring for 3 h, then lower the temperature to 45 °C, and then add 5 mL of dispersion two. After adding, further raise the temperature to 85 °C and continue to keep warm for 8 h, then centrifuge to separate the solid material, and after washing and vacuum drying, the modifier can be obtained.

[0037] Figure 1Scanning electron micrographs of sepiolite fiber and modifier, where (A) is sepiolite fiber and (B) is the modifier. It can be seen from the figure that the surface of sepiolite fiber is smooth and flat without obvious protrusions, while the modifier is obviously sepiolite fiber with nanoscale particles loaded on its surface. It can be speculated that the nanoscale particles are nano-titanium dioxide.

[0038] Example 1

[0039] A high-strength and impact-resistant PP composite material is made of raw materials including the following parts by weight:

[0040]

[0041] The preparation method of the PP composite material includes the following steps:

[0042] First step, weigh each raw material in sequence according to the parts by weight and set aside;

[0043] Second step, add polypropylene, modifier, compatibilizer, phosphite, and paraffin into a stirring kettle, control the rotation speed at 1000 r / min and the temperature at 120 °C, mechanically stir and mix for 60 min, then cool down and discharge to form a pre-mixed material;

[0044] Third step, feed the pre-mixed material into a twin-screw extruder, control the extrusion temperature at 200 °C and the screw rotation speed at 50 rpm, and through the melt extrusion granulation process, the PP composite material can be obtained.

[0045] Among them, the compatibilizer is maleic anhydride grafted polypropylene with a grafting rate of 1%; the preparation method of the modifier is shown in the preparation example, and the same applies hereinafter.

[0046] Example 2

[0047] A high-strength and impact-resistant PP composite material is made of raw materials including the following parts by weight:

[0048]

[0049] The preparation method of the PP composite material includes the following steps:

[0050] First step, weigh each raw material in sequence according to the parts by weight and set aside;

[0051] Second step, add polypropylene, modifier, compatibilizer, phosphite, and stearic acid into a stirring kettle, control the rotation speed at 1500 r / min and the temperature at 110 °C, mechanically stir and mix for 40 min, then cool down and discharge to form a pre-mixed material;

[0052] Step 3: Feed the pre-mixed material into a twin-screw extruder, control the extrusion temperature at 200 °C and the screw speed at 50 rpm, and through the melt extrusion granulation process, the PP composite material can be obtained.

[0053] Example 3

[0054] A high-strength and anti-stamping PP composite material is made of raw materials including the following parts by weight:

[0055]

[0056] The preparation method of the PP composite material includes the following steps:

[0057] Step 1: Weigh each raw material according to the parts by weight in sequence and set aside.

[0058] Step 2: Add polypropylene, modifier, compatibilizer, phosphite, and polyethylene wax into a stirring kettle, control the speed at 2000 r / min and the temperature at 120 °C, mechanically stir and mix for 30 min, then cool down and discharge to form a pre-mixed material.

[0059] Step 3: Feed the pre-mixed material into a twin-screw extruder, control the extrusion temperature at 200 °C and the screw speed at 50 rpm, and through the melt extrusion granulation process, the PP composite material can be obtained.

[0060] Comparative Example 1

[0061] A high-strength and anti-stamping PP composite material is made of raw materials including the following parts by weight:

[0062]

[0063]

[0064] The preparation method of the PP composite material includes the following steps:

[0065] Step 1: Weigh each raw material according to the parts by weight in sequence and set aside.

[0066] Step 2: Add polypropylene, sepiolite fiber, compatibilizer, phosphite, and stearic acid into a stirring kettle, control the speed at 1500 r / min and the temperature at 110 °C, mechanically stir and mix for 40 min, then cool down and discharge to form a pre-mixed material.

[0067] Step 3: Feed the pre-mixed material into a twin-screw extruder, control the extrusion temperature at 200 °C and the screw speed at 50 rpm, and through the melt extrusion granulation process, the PP composite material can be obtained.

[0068] Comparative Example 2

[0069] A high-strength anti-stamping PP composite material is made from raw materials including the following parts by weight:

[0070]

[0071] The preparation method of the PP composite material includes the following steps:

[0072] First step: Weigh each raw material according to the parts by weight in sequence and set aside for later use;

[0073] Second step: Add polypropylene, compatibilizer, phosphite, and stearic acid into a stirring kettle, control the rotation speed at 1500 r / min and the temperature at 110 °C, mechanically stir and mix for 40 min, then cool down and discharge to form a pre-mixed material;

[0074] Third step: Feed the pre-mixed material into a twin-screw extruder, control the extrusion temperature at 200 °C and the screw rotation speed at 50 rpm, and through the melt extrusion granulation process, the PP composite material can be obtained.

[0075] Test example

[0076] Make the PP composite materials prepared in the examples and comparative examples into test samples that meet the test specifications, and conduct various performance tests. The results are shown in the following table:

[0077] Table 1 - Test results of various performances

[0078] Tensile strength / MPa <![CDATA[Impact strength / kJ / m 2 > Wear loss / g Example 1 38.4 34.8 0.04 Example 2 39.0 35.1 0.03 Example 3 38.9 34.6 0.03 Comparative Example 1 34.1 29.0 0.10 Comparative Example 2 29.5 22.5 0.11

[0079] Among them, the test method for tensile strength refers to the standard GB / T 1040-1992; the test method for impact strength refers to the standard GB / T 1843-2008; the test method for abrasion loss refers to the standard ASTM D3884.

[0080] Analyzing the test results in Table 1, it can be seen that modifying polypropylene with the modifier in the preparation example can make the prepared composite material show excellent mechanical strength, and the wear resistance is also excellent.

[0081] After replacing the composite material with sepiolite fiber, due to the problem of interfacial incompatibility, the enhancement and modification effect of sepiolite fiber cannot be fully exerted, and due to the inability to produce a ball bearing effect, the mechanical strength and wear resistance of the composite material both decrease.

[0082] After completely removing the modifier, the enhancement effect of the fiber is lost, and the mechanical strength of the composite material is further reduced.

[0083] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention, including the best mode, and also enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements approximately the same as the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a high-strength and anti-impact PP composite material, characterized in that: The PP composite material is made of the following raw materials in parts by weight: The preparation method comprises the following steps: The first step is to weigh each raw material in parts by weight and set aside; Step 2: Add polypropylene, modifier, compatibilizer, antioxidant and lubricant into a stirring kettle, control the speed to 1000-2000r / min, the temperature to 100-120°C, mechanically stir and mix for 30-60min, cool and discharge to form a pre-mixed material; The third step is to feed the mixed material into a twin-screw extruder and obtain a PP composite material through a melt extrusion granulation process; The modifier is prepared by using a grafting agent as a connecting substance, and loading and connecting nano titanium dioxide and sepiolite fibers under the action of a tin metal catalyst; The grafting agent is prepared by using hydroxy-terminated nitrile rubber and benzoyl chloride modifier as reactants; The benzoyl chloride modifier is 4-isocyanatobenzoyl chloride or 3-isocyanatobenzoyl chloride.

2. The method for preparing a high-strength and anti-impact PP composite material according to claim 1, characterized in that: The preparation method of the modifier comprises the following steps: Step 1, dispersing sepiolite fiber in toluene to form a sepiolite fiber dispersion, which is referred to as dispersion 1; dispersing nano titanium dioxide in toluene to form a nano titanium dioxide dispersion, which is referred to as dispersion 2; Step 2, add the grafting agent to the dispersion one, and after adding, continue to add the tin metal catalyst, stir evenly, then increase the temperature to 70-80°C, keep stirring for 2-4 hours, reduce the temperature to 40-50°C, and then add the dispersion two, after adding, further increase the temperature to 80-90°C, continue to keep warm for 6-9 hours, centrifuge to separate the solid material, wash and vacuum dry to obtain the modifier.

3. The method for preparing a high-strength and anti-impact PP composite material according to claim 2, characterized in that: In step 1, the mass fraction of the dispersion 1 is 20-30%; the mass fraction of the dispersion 2 is 10-15%.

4. The method for preparing a high-strength and anti-impact PP composite material according to claim 2, characterized in that: In step 2, the preparation method of the grafting agent is as follows: The terminal hydroxyl nitrile rubber is mixed with tetrahydrofuran, stirred evenly, and then benzoyl chloride modifier and pyridine are added to the obtained uniform liquid material under ice bath conditions. After the addition is completed, the ice bath is removed, and after stirring at room temperature for 6-9 hours, the solvent is evaporated to remove and the material is separated to obtain the grafting agent.

5. The method for preparing a high-strength and anti-impact PP composite material according to claim 4, characterized in that: The molar ratio of the hydroxy-terminated nitrile rubber to the benzoyl chloride modifier is 1:

2.

6. The method for preparing a high-strength and anti-impact PP composite material according to claim 2, characterized in that: In step 2, the tin metal catalyst is any one of stannous octoate, dibutyltin diacetate or dibutyltin dilaurate.

7. The method for preparing a high-strength and anti-impact PP composite material according to claim 2, characterized in that: In step 2, the volume ratio of the dispersion 1 to the dispersion 2 is 1:0.2-0.

4.

8. The method for preparing a high-strength and anti-impact PP composite material according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene; the antioxidant is a phosphite antioxidant; and the lubricant is any one of paraffin wax, polyethylene wax or stearic acid.

9. A high-strength and anti-impact PP composite material, characterized in that: The method is prepared according to any one of claims 1 to 8.

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