High-heat-resistance modified PP resin and preparation method thereof

Abstract

The invention discloses high-heat-resistance modified PP (polypropylene) resin and a preparation method thereof. The high-heat-resistance modified PP resin comprises polypropylene, silicon dioxide, nano calcium carbonate, a heat-resistance modifier, an antioxidant, a stiffening agent, a coupling agent, a surfactant and a dispersing agent, the preparation method comprises the following steps: respectively dispersing silicon dioxide and nano calcium carbonate in ethanol, and then respectively carrying out reflux reaction with a coupling agent; respectively adding a surfactant into the silicon dioxide and the nano calcium carbonate, and stirring; respectively adding a dispersing agent into the surface-modified silicon dioxide and nano calcium carbonate; adding the heat-resistant modifier into the polypropylene resin to obtain a first auxiliary agent, adding the antioxidant into the polypropylene resin to obtain a second auxiliary agent, and adding the stiffening agent into the polypropylene resin to obtain a third auxiliary agent; and adding the dispersed silicon dioxide, nano calcium carbonate, a first auxiliary agent, a second auxiliary agent and a third auxiliary agent into polypropylene resin, and mixing to obtain the high-heat-resistance modified PP resin.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene plastics, and in particular to a highly heat-resistant modified PP resin and a preparation method thereof. Background Art

[0002] Polypropylene (PP) resin is a thermoplastic widely used in industry and daily life, known for its light weight, easy processing, chemical resistance and excellent heat resistance. The versatility of PP resin makes it the material of choice in many industries, and its application areas are also expanding, from traditional packaging materials, automotive accessories to more high-end medical equipment and electronic and electrical components.

[0003] However, traditional PP resin has some technical research defects, usually on the surface of PP resin at low temperature is relatively brittle, aging resistance and heat resistance is relatively poor, and easy to produce static electricity accumulation. These defects limit the development of PP resin in some high-end application fields. Summary of the invention

[0004] In view of the above shortcomings, the present invention provides a highly heat-resistant modified PP resin and a preparation method thereof to solve the problem of poor heat resistance of PP resin in the prior art.

[0005] The present invention first provides a highly heat-resistant modified PP resin, comprising the following components in parts by weight: 70-100 parts of polypropylene, 10-50 parts of silicon dioxide, 70-100 parts of nano calcium carbonate, 0.01-1 part of a heat resistance modifier, 0.01-1 part of an antioxidant, 0.01-1 part of a rigidifier, 0.5-1 part of a coupling agent, 0.5-1 part of a surfactant, and 0.01-1 part of a dispersant.

[0006] Preferably, the heat resistance modifier is selected from one or more of a β-crystal nucleating agent, an α-crystal nucleating agent and a γ-crystal nucleating agent.

[0007] Preferably, the antioxidant is selected from one or both of hindered phenol antioxidants and phosphite antioxidants.

[0008] Preferably, the coupling agent is selected from one or two of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltriethoxysilane and γ-glycidyloxypropyltriethoxysilane.

[0009] Preferably, the surfactant is selected from stearic acid.

[0010] The present invention also provides a method for preparing the above-mentioned synthetic high heat-resistant modified PP resin, characterized in that it comprises:

[0011] S1, dispersing silicon dioxide and nano calcium carbonate in ethanol respectively and then reflux reacting with a coupling agent respectively;

[0012] S2, adding a surfactant to the silicon dioxide and nano-calcium carbonate obtained by the reflux reaction in step S1, respectively, and stirring them to obtain surface-modified silicon dioxide and nano-calcium carbonate;

[0013] S3, adding dispersants to the surface-modified silicon dioxide and nano-calcium carbonate in step S2 for dispersion treatment;

[0014] S4, adding a heat resistance modifier to the polypropylene resin and stirring at high speed to obtain a first auxiliary agent, adding an antioxidant to the polypropylene resin and stirring at high speed to obtain a second auxiliary agent, and adding a stiffening agent to the polypropylene resin and stirring at high speed to obtain a third auxiliary agent;

[0015] S5, adding the silicon dioxide and nano-calcium carbonate dispersed in step S3, the first auxiliary agent, the second auxiliary agent and the third auxiliary agent in step S4 into the polypropylene resin for mixing to obtain a highly heat-resistant modified PP resin.

[0016] Preferably, in step S1, the mass ratio of silicon dioxide to ethanol is 1:3-5, the mass ratio of nano-calcium carbonate to ethanol is 1:3-5, the temperature of the reflux reaction is 70° C.-90° C., and the reflux reaction time is 2 h-4 h.

[0017] Preferably, in step S2, the stirring temperature of silicon dioxide and surfactant is 80°C to 100°C, and the stirring time is 15min to 30min, and the stirring temperature of nano-calcium carbonate and surfactant is 70°C to 90°C, and the stirring time is 15min to 30min.

[0018] Preferably, in step S3, the mass ratio of the heat resistance modifier to the polypropylene resin is 1-2:1-3, the mass ratio of the antioxidant to the polypropylene resin is 1-3:3-6, and the mass ratio of the stiffening agent to the polypropylene resin is 1-2:1-3.

[0019] Preferably, the mixing temperature in step S5 is 200°C to 250°C.

[0020] In the present invention, modified silicon dioxide and nano calcium carbonate are added to the PP resin. The silicon dioxide itself has good heat resistance, and its silicon oxygen bond can remain stable at a high temperature. When it is compounded with the polypropylene resin, it can limit the softening and deformation of the polypropylene molecular chain caused by thermal motion to a certain extent under a high temperature environment, maintain the shape and dimensional stability of the material, and can increase the thermal deformation temperature of the PP resin, so that it can be used normally at a relatively high temperature; secondly, silicon dioxide has high hardness and rigidity, which can significantly improve the mechanical properties of the PP resin such as tensile strength, bending strength and modulus. The particle size of nano calcium carbonate is very small, usually at the nanometer level, and has a large specific surface area. When it is added to the polypropylene resin, it can fully contact and interact with the polypropylene molecular chain, playing a role of filling and strengthening. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0022] Figure 1 The present invention provides a flow chart of a method for preparing a synthetic high heat-resistant modified PP resin. DETAILED DESCRIPTION

[0023] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0025] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If the terms "first", "second", "third" are described, they are only used for the purpose of description and distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] A highly heat-resistant modified PP resin comprises the following components in parts by weight: 70-100 parts of polypropylene, 10-50 parts of silicon dioxide, 70-100 parts of nano calcium carbonate, 0.01-1 part of a heat resistance modifier, 0.01-1 part of an antioxidant, 0.01-1 part of a rigidifier, 0.5-1 part of a coupling agent, 0.5-1 part of a surfactant and 0.01-1 part of a dispersant.

[0028] Specifically, the silicon dioxide is nano silicon dioxide.

[0029] As a preferred embodiment, the heat resistance modifier is selected from one or more of a β-crystal nucleating agent, an α-crystal nucleating agent and a γ-crystal nucleating agent.

[0030] In a more preferred embodiment, the heat resistance modifier is selected from β-crystalline nucleating agents.

[0031] As a preferred embodiment, the antioxidant is selected from one or both of hindered phenol antioxidants and phosphite antioxidants.

[0032] In a more preferred embodiment, the antioxidant is selected from two of hindered phenol antioxidants and phosphite antioxidants.

[0033] As a preferred embodiment, the coupling agent is selected from one or two of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltriethoxysilane and γ-glycidyloxypropyltriethoxysilane.

[0034] In a more preferred embodiment, the coupling agent is selected from the silane coupling agent γ-aminopropyltriethoxysilane (KH-550).

[0035] As a preferred embodiment, the surfactant is selected from stearic acid.

[0036] A method for preparing the above-mentioned synthetic high heat-resistant modified PP resin comprises:

[0037] S1. Disperse silicon dioxide and nano calcium carbonate in ethanol respectively and then reflux react with a coupling agent respectively.

[0038] The use of coupling agent can enhance the compatibility and bonding force between silicon dioxide and PP resin; the use of coupling agent can improve the dispersibility of nano calcium carbonate in PP resin.

[0039] In a specific implementation scheme, the mass ratio of silicon dioxide to ethanol is 1:3-5, the mass ratio of nano-calcium carbonate to ethanol is 1:3-5, the temperature of the reflux reaction is 70° C.-90° C., and the reflux reaction time is 2h-4h.

[0040] S2, adding surfactants to the silicon dioxide and nano-calcium carbonate obtained by the reflux reaction in step S1 respectively, and stirring them to obtain surface-modified silicon dioxide and nano-calcium carbonate.

[0041] In a specific implementation manner, in step S2, the stirring temperature of silicon dioxide and surfactant is 80°C to 100°C, and the stirring time is 15min to 30min, and the stirring temperature of nano-calcium carbonate and surfactant is 70°C to 90°C, and the stirring time is 15min to 30min.

[0042] Surfactants are used to reduce the surface energy of silica, making it easier to disperse in PP resin; stearic acid is used to treat nano-calcium carbonate to improve its surface activity, making it easier to disperse in PP resin and improving the processing fluidity of the material.

[0043] When the coupling agent and the surfactant are used to treat the surface of silicon dioxide and nano-calcium carbonate, the mass of the coupling agent is 1% to 5%, and the mass of the surfactant is 2% to 8%.

[0044] S3, adding dispersants to the surface-modified silicon dioxide and nano-calcium carbonate in step S2 for dispersion treatment.

[0045] In a specific implementation scheme, a method combining mechanical stirring and ultrasonic dispersion is used to disperse silicon dioxide and nano calcium carbonate respectively, and a dispersant is added to the stirred raw materials, so that the two can be evenly dispersed in the PP resin, thereby improving the performance of the material. The dispersant is an aqueous system emulsifying dispersant.

[0046] S4. Add a heat resistance modifier to the polypropylene resin and stir it at high speed to obtain a first auxiliary agent, add an antioxidant to the polypropylene resin and stir it at high speed to obtain a second auxiliary agent, and add a stiffening agent to the polypropylene resin and stir it at high speed to obtain a third auxiliary agent.

[0047] The mass percentage of the heat resistance modifier and the polypropylene resin is 1:8-10, the mass percentage of the antioxidant and the polypropylene resin is 1:8-10, and the mass percentage of the stiffening agent and the polypropylene resin is 1:8-10.

[0048] In a specific preferred embodiment, the β-crystalline nucleating agent is premixed with a small amount of polypropylene resin in a high-speed mixer to form a premix, which is used as the first auxiliary agent; the hindered phenol antioxidant and the phosphite antioxidant are premixed with a small amount of polypropylene resin to form an antioxidant premix, which is used as the second auxiliary agent; the nucleating agent ZGJ-7 is mixed with a small amount of polypropylene resin to form a premix, which is used as the third auxiliary agent.

[0049] S5, adding the silicon dioxide and nano-calcium carbonate dispersed in step S3, the first auxiliary agent, the second auxiliary agent and the third auxiliary agent in step S4 into the polypropylene resin for mixing to obtain a synthetic high heat-resistant modified PP resin.

[0050] In a specific embodiment, the dispersed silicon dioxide and the first, second and third nano-calcium carbonate additives are added to polypropylene resin for high-temperature mixing and stirring at a temperature of 200°C to 250°C.

[0051] Example 1

[0052] This embodiment 1 provides a high heat-resistant modified PP resin and a preparation method thereof, which are as follows:

[0053] Step 1: Material selection

[0054] Select the following components by weight:

[0055] 90 parts of polypropylene; 20 parts of nano-silicon dioxide; 90 parts of nano-calcium carbonate; 0.09 parts of β-crystalline nucleating agent; 0.09 parts of hindered phenol antioxidant (Irganox 1425); 0.09 parts of phosphite antioxidant (Irgafos P-EPQ); 0.09 parts of rigidity enhancing agent (nucleating agent ZGJ-7); 0.09 parts of dispersant (cfc-602w); 0.6 parts of γ-aminopropyltriethoxysilane (KH-550); 0.6 parts of stearic acid.

[0056] 2. Surface treatment

[0057] 1. Coupling agent treatment

[0058] (1) Dispersing silica in ethanol (mass ratio of silica to ethanol is 1:3-5) and reflux reacting with silane coupling agent (γ-aminopropyltriethoxysilane (KH-550)) at 70°C-90°C for 2-4 hours to enhance the compatibility and bonding strength between silica and PP resin.

[0059] (2) Dispersing nano-calcium carbonate in ethanol (the mass ratio of nano-calcium carbonate to solvent is 1:3-1:5) and reflux reacting with a silane coupling agent (γ-aminopropyltriethoxysilane (KH-550)) at 70°C to 90°C for 2-3 hours, thereby improving the dispersibility of nano-calcium carbonate in PP resin.

[0060] 2. Stearic acid treatment

[0061] (1) Place silica in a high-speed mixer, add stearic acid, and stir at 80°C to 100°C for 15 to 30 minutes to reduce its surface energy and make it easier to disperse in the PP resin.

[0062] (2) Place nano calcium carbonate in a high-speed mixer, add stearic acid, and stir at 70°C to 90°C for 15 to 30 minutes to make it easier to disperse in the PP resin and improve the processing fluidity of the material.

[0063] Step 3: Distributed processing

[0064] The silicon dioxide and nano-calcium carbonate obtained in step 2 are dispersed and used respectively by combining mechanical stirring and ultrasonic dispersion, and an aqueous system emulsifier is added to the stirred raw materials to make the two uniformly dispersed in the PP resin, thereby improving the performance of the material.

[0065] Step 4: Pretreatment of additives

[0066] 1. Take a small amount of PP resin as a carrier, put the β-crystal nucleating agent and the carrier PP resin into a high-speed mixer, set the mixer speed to 1000-1500r / min, and control the mixing time to 5-10 minutes to make a premix. Among them, the amount of PP resin is 10 times the amount of the added β-crystal nucleating agent.

[0067] 2. Take a small amount of PP resin, mix it with hindered phenol antioxidants and phosphite antioxidants, put it into a high-speed mixer, and mix it at a speed of 800-1200r / min for 5-8 minutes to make a premix. Among them, the amount of PP resin is 10 times the amount of hindered phenol antioxidants and phosphite antioxidants added.

[0068] 3. Take a small amount of PP resin and put it into a high-speed mixer together with the nucleating agent ZGJ-7, control the mixing speed at 1000-1500r / min, and the mixing time is 5-10 minutes to make a premix. Among them, the amount of PP resin is 10 times the amount of the added nucleating agent ZGJ-7.

[0069] Step 5: Mixing raw materials

[0070] The pretreated nano-calcium carbonate and silicon dioxide and the premix obtained in step 4 are added to the PP resin, and the mixed materials are added to a twin-screw extruder. Under the conditions of a temperature of 210°C and a screw speed of 300r / min, the mixture is melted, extruded, water-cooled, dried, and pelletized by the twin-screw extruder to obtain a synthetic high heat-resistant modified PP resin. The mixing mass ratio of nano-calcium carbonate, silicon dioxide, and PP resin in this step is:

[0071] Polypropylene: nano calcium carbonate: silicon dioxide is 45%:45%:10%.

[0072] Step 6: Post-processing

[0073] The high heat-resistant modified PP resin obtained in step 5 is taken out from the reactor, and molded as needed, and then made into the desired product shape through injection molding and extrusion, and then the product performance is tested and evaluated. Among them, in the performance test and evaluation, the instruments used for the relevant performance test of the high heat-resistant modified PP resin are as follows:

[0074] Heat resistance: Heat deformation Vicat softening point tester.

[0075] Tensile strength: universal testing machine.

[0076] Flexural modulus: universal testing machine.

[0077] Thermal conductivity: Guarded heat flow method thermal conductivity tester.

[0078] Example 2

[0079] Embodiment 2 of the present invention provides a highly heat-resistant modified PP resin and a preparation method thereof, which are as follows:

[0080] Step 1: Material selection

[0081] The following components were selected by weight: 80 parts of polypropylene; 40 parts of nano-silicon dioxide; 80 parts of nano-calcium carbonate; 0.08 parts of β-crystalline nucleating agent; 0.08 parts of hindered phenol antioxidant (Irganox 1425); 0.08 parts of phosphite antioxidant (Irgafos P-EPQ); 0.08 parts of stiffening agent (nucleating agent ZGJ-7); 0.08 parts of dispersant (cfc-602w); 1.2 parts of silane coupling agent (γ-aminopropyltriethoxysilane (KH-550)); 1.2 parts of stearic acid.

[0082] The remaining steps are the same as those in Example 1, wherein in step 5, the mixing mass ratio of nano-calcium carbonate, silicon dioxide and PP resin is: polypropylene: nano-calcium carbonate: silicon dioxide is 40%:40%:20%.

[0083] Comparative Example 1

[0084] Comparative Example 1 provides a PP resin. Comparative Example 1 is the blank control group of the above-mentioned Example 1. In Comparative Example 1, nano silicon dioxide and an auxiliary agent for pretreating nano silicon dioxide are not added.

[0085] Comparative Example 2

[0086] Comparative Example 2 provides a PP resin. Comparative Example 2 is the blank control group of the above-mentioned Example 2. In Comparative Example 2, no nano-silicon dioxide and no auxiliary agent for pretreating the nano-silicon dioxide are added.

[0087] The PP resin samples obtained by Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were tested, and the test results are shown in Table 1 below.

[0088]

[0089] Representation 1

[0090] It can be seen from Table 1 that the heat deformation temperature, tensile strength and thermal conductivity of the sample obtained in Example 1 in Comparative Example 1 and Example 1 are higher than those of the sample in Comparative Example 1, and the heat deformation temperature, tensile strength and thermal conductivity of the sample obtained in Example 2 in Comparative Example 2 and Example 1 are higher than those of the sample in Comparative Example 2. It can be seen that silica, as a heat-resistant filler, cooperates with other functional additives in the sample to improve the heat resistance and mechanical properties such as tensile strength, flexural strength and modulus of the PP resin.

[0091] Plastics with high heat deformation temperature can still maintain good mechanical properties and shape stability in high temperature environments, and are relatively less likely to soften, deform, and then crack due to temperature rise. Plastics with high heat deformation temperature, high tensile strength, high bending modulus, and high thermal conductivity have stable structures and can slow down the aging process of plastics.

[0092] By comparing Example 1 and Example 2, the test parameters of the sample obtained in Example 2 are better than those of the sample in Example 1. By adding an appropriate amount of silicon dioxide and adjusting other functionalities, the synthesized PP resin exhibits excellent heat resistance, aging resistance and low brittleness.

[0093] In summary, in the present invention, nano-silicon dioxide is added to the PP resin. The nano-silicon dioxide has a small particle size and a large specific surface area, can be evenly dispersed in the PP resin, and forms a good interface bonding with the PP resin to improve the comprehensiveness of the material. The addition of nano-silicon dioxide can improve the strength, rigidity and wear resistance of the PP resin while maintaining the good toughness and processing properties of the material. The heat deformation temperature of the PP resin in the present invention can be increased by 20°C to 40°C, which can meet the application requirements in some high temperature environments.

[0094] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A highly heat-resistant modified PP resin, characterized in that: The invention comprises the following components in parts by weight: 70-100 parts of polypropylene, 10-50 parts of silicon dioxide, 70-100 parts of nano calcium carbonate, 0.01-1 part of heat resistance modifier, 0.01-1 part of antioxidant, 0.01-1 part of rigidifier, 0.5-1 part of coupling agent, 0.5-1 part of surfactant and 0.01-1 part of dispersant.

2. A highly heat-resistant modified PP resin according to claim 1, characterized in that: The heat resistance modifier is selected from one or more of a β-crystal nucleating agent, an α-crystal nucleating agent and a γ-crystal nucleating agent.

3. The high heat-resistant modified PP resin according to claim 1, characterized in that: The antioxidant is selected from one or both of hindered phenol antioxidants and phosphite antioxidants.

4. The high heat-resistant modified PP resin according to claim 1, characterized in that: The coupling agent is selected from one or two of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltriethoxysilane and γ-glycidyloxypropyltriethoxysilane.

5. The highly heat-resistant modified PP resin according to claim 1, characterized in that: The surfactant is selected from stearic acid.

6. A method for preparing a highly heat-resistant modified PP resin as claimed in any one of claims 1 to 5, characterized in that: include: S1, dispersing silicon dioxide and nano calcium carbonate in ethanol respectively and then reflux reacting with a coupling agent respectively; S2, adding a surfactant to the silicon dioxide and nano-calcium carbonate obtained by the reflux reaction in step S1, respectively, and stirring them to obtain surface-modified silicon dioxide and nano-calcium carbonate; S3, adding dispersants to the surface-modified silicon dioxide and nano-calcium carbonate in step S2 for dispersion treatment; S4, adding a heat resistance modifier to the polypropylene resin and stirring at high speed to obtain a first auxiliary agent, adding an antioxidant to the polypropylene resin and stirring at high speed to obtain a second auxiliary agent, and adding a stiffening agent to the polypropylene resin and stirring at high speed to obtain a third auxiliary agent; S5, adding the silicon dioxide and nano-calcium carbonate dispersed in step S3, the first auxiliary agent, the second auxiliary agent and the third auxiliary agent in step S4 into the polypropylene resin for mixing to obtain a highly heat-resistant modified PP resin.

7. The method for preparing a highly heat-resistant modified PP resin according to claim 6, characterized in that: In the step S1, the mass ratio of silicon dioxide to ethanol is 1:3-5, the mass ratio of nano-calcium carbonate to ethanol is 1:3-5, the temperature of the reflux reaction is 70° C.-90° C., and the reflux reaction time is 2h-4h.

8. The method for preparing a highly heat-resistant modified PP resin according to claim 6, characterized in that: In step S2, the stirring temperature of silicon dioxide and surfactant is 80°C-100°C, and the stirring time is 15min-30min; the stirring temperature of nano-calcium carbonate and surfactant is 70°C-90°C, and the stirring time is 15min-30min.

9. The method for preparing a highly heat-resistant modified PP resin according to claim 6, characterized in that: In the step S3, the mass ratio of the heat resistance modifier to the polypropylene resin is 1:8-10, the mass ratio of the antioxidant to the polypropylene resin is 1:8-10, and the mass ratio of the stiffening agent to the polypropylene resin is 1:8-10.

10. The method for preparing a highly heat-resistant modified PP resin according to claim 6, characterized in that: The mixing temperature in step S5 is 200°C to 250°C.

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