High-melt-index heavy calcium carbonate filled master batch and preparation method thereof

Abstract

The invention provides a high-melt-index heavy calcium carbonate filled master batch and a preparation method thereof, and belongs to the technical field of plastic master batches. The liquid dispersing agent and the solid long carbon chain stearic acid are added, the calcium carbonate is pretreated by using a mechanical force modification process of a high-speed stirrer, and the PP resin is pretreated by using the fatty acid ester internal lubricant, so that the PP resin is more easily compatible with the pretreated calcium carbonate particles in the mixing process. The high-temperature-resistant PPA powder and the antistatic agent are added into the formula, and the materials are mixed in combination with a fractional step method, so that the processing flowability is greatly improved, and the production cost is remarkably reduced. The technical route and formula design of the invention have important significance.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic masterbatches, and particularly to a high melt index heavy calcium carbonate filled masterbatch and a preparation method thereof. Background Art

[0002] A filled masterbatch refers to pellets obtained by mixing various required additives, fillers and a small amount of carrier resin for convenient operation during the plastic processing and molding process. A PP (polypropylene) filled masterbatch is a type of masterbatch processed with PP as the carrier, adding calcium carbonate and other additives, and is widely used in industries such as wire drawing, film, pipe, and hollow blow molding due to its advantages such as convenient transportation, easy feeding, and good dispersibility.

[0003] Heavy calcium carbonate is an inorganic powder prepared by physically grinding natural calcium carbonate ore such as calcite, marble, and dolomite. It is commonly used as a filler for polypropylene filled masterbatches due to its advantages such as white color, good thermal stability, non-toxicity, odorlessness, and no smell.

[0004] However, due to the strong surface polarity of heavy calcium carbonate and poor compatibility with polypropylene, especially when it is prepared into a masterbatch, due to the high calcium carbonate content, it is very easy to cause an increase in melt pressure, a large melt index, and poor processing fluidity. Traditional polypropylene filled masterbatches use the method of mixing polypropylene, calcium carbonate, and processing aids together through a high-speed mixing blender, and add a large amount of lubricants to increase the melt index and improve the processing fluidity. This method has a relatively high cost, and the lubricants are easily volatilized during the high-speed mixing and extrusion processing, and their effects cannot be fully exerted. At the same time, due to the extensive mixing method when preparing masterbatches with high calcium carbonate filling, the masterbatches are prone to breaking, and the production continuity and stability are poor.

[0005] The melt index, also known as the solution flow index or melt flow index, is a value representing the fluidity of a plastic material during processing. The larger the value, the better the processing fluidity of the plastic material, and vice versa.

[0006] With the low-cost demand in the polypropylene masterbatch market and the high-speed production requirements of masterbatch applications in end customers, developing high melt index heavy calcium carbonate filled masterbatches has broad market prospects. Based on the above needs, it is of great significance to develop high melt index heavy calcium carbonate filled masterbatches. Summary of the Invention

[0007] The purpose of the present invention is to provide a high melt index heavy calcium carbonate filled masterbatch and a preparation method thereof to solve the above technical problems.

[0008] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing a high melt index heavy calcium carbonate filled masterbatch, comprising the following steps:

[0010] Step 1), mixing heavy calcium carbonate, a dispersant and a modifier for pretreatment to obtain modified heavy calcium carbonate;

[0011] Step 2), mixing polypropylene and a modifier and then performing pretreatment to obtain modified polypropylene;

[0012] Step 3), mixing the modified heavy calcium carbonate, the modified polypropylene, polyethylene wax, zinc stearate, PPA powder and an antistatic agent, and successively performing extrusion, pelletizing and granulation to obtain the high melt index heavy calcium carbonate filled masterbatch.

[0013] Further, in step 1), the particle size of the heavy calcium carbonate is D50 of 2 μm to 3 μm, D97 of 6 μm to 8 μm, and the oil absorption value is 27 to 30 ml / 100 g;

[0014] The addition amount of the dispersant is 0.8 to 2% of the mass of the heavy calcium carbonate, and the addition amount of stearic acid is 0.5 to 0.9% of the mass of the heavy calcium carbonate;

[0015] The dispersant includes ethylene glycol, and the modifier includes stearic acid.

[0016] Further, in step 1), the pretreatment is carried out under stirring, the stirring speed is 300 to 900 r / min, the pretreatment time is 10 to 30 min, and the pretreatment temperature is 105 to 120 °C.

[0017] Further, in step 2), the polypropylene is powder;

[0018] The addition amount of the modifier is 4 to 9‰ of the mass of the polypropylene;

[0019] The modifier includes one or more of methyl stearate, butyl stearate, methyl 2-hydroxy stearate, methyl 12-hydroxy stearate and octyl epoxy stearate.

[0020] Further, in step 2), the pretreatment is carried out under stirring, the stirring speed is 500 to 1500 r / min, the pretreatment time is 15 to 60 min, and the pretreatment temperature is 50 to 80 °C.

[0021] Further, in step 3), by mass fraction, the addition amounts of each component are as follows: 70 to 80 parts of heavy calcium carbonate, 15 to 25 parts of modified polypropylene, 1 to 5 parts of polyethylene wax, 0.5 to 2 parts of zinc stearate, 0.05 to 0.2 parts of PPA powder, and 0.5 to 2 parts of antistatic agent;

[0022] The PPA powder is a mixture of vinylidene fluoride, hexafluoropropylene copolymer and synthetic ester.

[0023] Furthermore, in step 3), the antistatic agent is a non-ionic antistatic agent;

[0024] The non-ionic antistatic agent includes fatty acid polyol ester and / or polyethylene oxide.

[0025] Furthermore, in step 3), the mixing is carried out under stirring, the stirring speed is 250 - 500 r / min, the stirring time is 10 - 40 min, and the stirring temperature is 70 - 100 °C.

[0026] Furthermore, in step 3), the extrusion temperature is 200 - 240 °C.

[0027] The present invention also provides a high melt index heavy calcium carbonate filled masterbatch prepared by the above preparation method.

[0028] Advantages of the present invention:

[0029] The present invention uses pretreated heavy calcium carbonate, and by adding a liquid dispersant and solid long-chain stearic acid, the heavy calcium carbonate is pretreated by a process of mechanical force modification using a high-speed mixer. After pretreatment, in the presence of both the dispersant and the modifier, an organic molecular layer is coated on the particle surface, enhancing the repulsive force between particles and making it easier for subsequent inorganic particles and PP resin to bind together.

[0030] The present invention uses pretreated PP resin for mixing, and a fatty acid ester internal lubricant is added during the pretreatment process. The internal lubricant can be relatively easily inserted between resin particles and between segments within the molecule. By performing pretreatment before processing, a complex bond is formed between the internal lubricant and the PP resin, and at the same time, through high-speed shearing action, a strong binding force is formed between the polar part of the internal lubricant and the PP resin. Fatty acid ester lubricants are more likely to be compatible with the pretreated calcium carbonate particles during the mixing process due to the presence of multiple polar ester groups and multiple non-polar alkyl groups in the molecule.

[0031] The present invention adds a non-ionic antistatic agent during the mixing process. The non-ionic antistatic agent has good processability and thermal stability, and can also eliminate agglomeration during the mixing process. By adding the antistatic agent, a more continuous compatible layer is formed in the mixed material, improving its processing fluidity.

[0032] In the process of optimizing the formula of the present invention, a high-temperature resistant PPA powder with relatively high cost performance (the main components of which are vinylidene fluoride and hexafluoropropylene copolymer, synthetic ester and other additives) is added. This product is a high-efficiency lubricant based on fluoropolymer, and such lubricants have a significant effect on improving processing performance and rheological state.

[0033] The present invention uses a step-by-step method for mixing materials, pre-treating calcium carbonate and polypropylene at high speed, and mixing materials at low speed, and conducts regulation and design on the formula combination, so that the production cost of the masterbatch is lower.

[0034] The present invention uses the method of water ring pelletizing for pelletizing. Compared with the traditional air-cooled pelletizing method, it reduces dust emissions. Specific embodiments

[0035] The present invention provides a method for preparing a high melt index heavy calcium carbonate filled masterbatch, which includes the following steps:

[0036] Step 1): Mix heavy calcium carbonate, dispersant and modifier for pretreatment to obtain modified heavy calcium carbonate;

[0037] Step 2): Mix polypropylene and modifier and then conduct pretreatment to obtain modified polypropylene;

[0038] Step 3): Mix modified heavy calcium carbonate, modified polypropylene, polyethylene wax, zinc stearate, PPA powder and antistatic agent, and successively conduct extrusion, granulation and pelletizing to obtain the high melt index heavy calcium carbonate filled masterbatch.

[0039] In the present invention, in step 1), the particle size of the heavy calcium carbonate is D50 of 2 μm to 3 μm, preferably 2.5 μm; D97 is 6 μm to 8 μm, preferably 6.5 μm; the oil absorption value is 27 to 30 mL / 100 g, preferably 29 mL / 100 g;

[0040] The addition amount of the dispersant is 0.8 to 2% of the mass of the heavy calcium carbonate, preferably 1.5%; the addition amount of stearic acid is 0.5 to 0.9% of the mass of the heavy calcium carbonate, preferably 0.7%;

[0041] The dispersant is preferably ethylene glycol, and the modifier is preferably stearic acid.

[0042] In the present invention, the heavy calcium carbonate is processed from ultrafine calcite powder.

[0043] In the present invention, in step 1), the pretreatment is carried out under stirring, the stirring speed is 300 - 900 r / min, preferably 400 - 800 r / min, and more preferably 600 r / min; the pretreatment time is 10 - 30 min, preferably 15 min; the pretreatment temperature is 105 - 120 °C, preferably 110 °C.

[0044] In the present invention, in step 2), the polypropylene is in powder form;

[0045] The addition amount of the modifier is 4 - 9‰ of the mass of the polypropylene, preferably 6‰;

[0046] The modifier includes one or more of methyl stearate, butyl stearate, methyl 2 - hydroxystearate, methyl 12 - hydroxystearate, and octyl epoxy stearate, preferably one or more of methyl stearate, butyl stearate, methyl 2 - hydroxystearate, and methyl 12 - hydroxystearate, and more preferably one or more of methyl stearate, butyl stearate, and methyl 2 - hydroxystearate.

[0047] In the present invention, the polypropylene preferably has a melt index (230 °C, 2.16 Kg) of 20 - 28 g / 10 min, and more preferably 25 g / 10 min.

[0048] In the present invention, in step 2), the pretreatment is carried out under stirring, the stirring speed is 500 - 1500 r / min, preferably 800 - 1200 r / min, and more preferably 1050 r / min; the pretreatment time is 15 - 60 min, preferably 20 - 50 min, and more preferably 30 min; the pretreatment temperature is 50 - 80 °C, preferably 60 - 70 °C, and more preferably 65 °C.

[0049] In the present invention, in step 3), by mass parts, the addition amounts of the respective components are as follows: 70 - 80 parts of heavy calcium carbonate, 15 - 25 parts of modified polypropylene, 1 - 5 parts of polyethylene wax, 0.5 - 2 parts of zinc stearate, 0.05 - 0.2 parts of PPA powder, and 0.5 - 2 parts of antistatic agent;

[0050] The PPA powder is a mixture of vinylidene fluoride, hexafluoropropylene copolymer, and synthetic ester.

[0051] In the present invention, by mass parts, the addition amount of the heavy calcium carbonate is preferably 72 - 78 parts, and more preferably 75 parts;

[0052] In the present invention, by mass parts, the addition amount of the modified polypropylene is preferably 18 - 22 parts, and more preferably 20 parts;

[0053] In the present invention, the addition amount of polyethylene wax is preferably 3 parts by mass;

[0054] In the present invention, the addition amount of zinc stearate is preferably 0.7 - 1.5 parts by mass, and more preferably 1 part;

[0055] In the present invention, the addition amount of PPA powder is preferably 0.1 - 0.15 parts by mass, and more preferably 0.13 parts;

[0056] In the present invention, the addition amount of antistatic agent is preferably 1 - 1.5 parts by mass, and more preferably 1.3 parts.

[0057] In the present invention, the mass percentage of the sum of vinylidene fluoride and hexafluoropropylene copolymer in the PPA powder to the synthetic ester is preferably 30 - 40%: 60 - 70%;

[0058] In the present invention, in step 3), the antistatic agent is a non-ionic antistatic agent;

[0059] The non-ionic antistatic agent includes fatty acid polyol ester and / or polyethylene oxide, preferably fatty acid polyol ester and polyethylene oxide.

[0060] In the present invention, in step 3), the mixing is carried out under stirring, the stirring speed is 250 - 500 r / min, preferably 300 - 450 r / min, and more preferably 400 r / min; the stirring time is 10 - 40 min, preferably 20 - 30 min, and more preferably 25 min; the stirring temperature is 70 - 100 °C, preferably 80 - 90 °C, and more preferably 85 °C.

[0061] In the present invention, in step 3), the extrusion temperature is 200 - 240 °C, preferably 220 - 230 °C, and more preferably 225 °C.

[0062] The present invention also provides a high melt index heavy calcium carbonate filled masterbatch prepared by the above preparation method.

[0063] In the present invention, polypropylene powder: Jiaxing Sanjiang Haojia New Polymer Materials Technology Co., Ltd., grade: PPH, HD, 225; polyethylene wax: Guangdong Bangnida Chemical Industry Co., Ltd., model 100S; zinc stearate: Dongguan Hanwei New Materials Technology Co., Ltd., model AV320; PPA powder: Shanghai Songshan New Materials Technology Co., Ltd., model SS-802H; polyethylene oxide: Shanghai Youdao Aoba Chemical Co., Ltd., model 301.

[0064] The technical solution provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0065] Example 1

[0066] 70 kg of heavy calcium carbonate with a fineness of D50 of 2.52 μm, D97 of 6.89 μm, and an oil absorption value of 29 ml / 100 g, 1.05 kg of stearic acid 1801, and 490 g of ethylene glycol were fed into a high-speed mixer and pretreated for 15 min under the conditions of a rotation speed of 600 r / min and a temperature of 110 °C to obtain modified heavy calcium carbonate;

[0067] 20 kg of polypropylene powder and 120 g of methyl stearate were fed into a high-speed mixing mixer and pretreated for 30 min under the conditions of a rotation speed of 1050 r / min and a temperature of 65 °C to obtain modified polypropylene;

[0068] All the above-obtained modified heavy calcium carbonate and modified polypropylene were fed into a low-speed mixer, 3 kg of polyethylene wax, 1 kg of zinc stearate, 0.1 kg of PPA powder, and 1 kg of polyethylene oxide were added, and low-speed stirring was carried out for 20 min under the conditions of a rotation speed of 350 r / min and a temperature of 90 °C. Then, the obtained mixture was subjected to extrusion processing using a horizontal twin-screw extruder with a screw diameter of 75 mm (aspect ratio 56:1), and the extrusion temperature was 220 °C. After water ring pelletization, a high melt index heavy calcium carbonate filled masterbatch was prepared.

[0069] Example 2

[0070] In this example, different from Example 1, in the preparation of modified heavy calcium carbonate, 75 kg of heavy calcium carbonate with a fineness of D50 of 2.52 μm, D97 of 6.89 μm, and an oil absorption value of 29 ml / 100 g, 1.125 kg of stearic acid 1801, and 525 g of ethylene glycol were fed into a high-speed mixer and pretreated for 15 min under the conditions of a rotation speed of 600 r / min and a temperature of 110 °C to obtain modified heavy calcium carbonate.

[0071] Example 3

[0072] In this example, different from Example 1, in the preparation of modified heavy calcium carbonate, 80 kg of heavy calcium carbonate with a fineness of D50 of 2.52 μm, D97 of 6.89 μm, and an oil absorption value of 29 ml / 100 g, 1.2 kg of stearic acid 1801, and 560 g of ethylene glycol were fed into a high-speed mixer and pretreated for 15 min under the conditions of a rotation speed of 600 r / min and a temperature of 110 °C to obtain modified heavy calcium carbonate.

[0073] Example 4

[0074] In this embodiment, different from Embodiment 2, in the preparation of modified polypropylene, 20 kg of polypropylene powder, 60 g of methyl stearate and 60 g of methyl 2-hydroxy stearate are transported to a high-speed mixing blender and pretreated at a rotation speed of 1050 r / min and a temperature of 65 °C for 30 min to obtain modified polypropylene.

[0075] Comparative Example 1

[0076] Different from Embodiment 4, in this comparative example, unmodified heavy calcium carbonate and unmodified polypropylene are used to prepare the masterbatch.

[0077] Comparative Example 2

[0078] Different from Embodiment 4, in this comparative example, unmodified heavy calcium carbonate is used.

[0079] Comparative Example 3

[0080] Different from Embodiment 4, in this comparative example, unmodified polypropylene powder is used.

[0081] Comparative Example 4

[0082] Different from Embodiment 4, in this comparative example, PPA powder is not added.

[0083] Comparative Example 5

[0084] Different from Embodiment 4, in this comparative example, antistatic agent is not added.

[0085] The masterbatches prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are respectively tested for melt index and filter press value, and the results are shown in Table 1. Among them, the melt index is tested according to GB / T3682-2018, and the filter press value is tested according to Q2002-037T.

[0086] Table 1 Melt index and filter press value of the masterbatches prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0087] Masterbatch number Melt index (g / 10 min) Pressure filtration value Example 1 28.5 12.6 Example 2 36.8 10.2 Example 3 22.5 14.6 Example 4 36.2 10.3 Comparative Example 1 16.3 18.9 Comparative Example 2 17.4 16.5 Comparative Example 3 19.2 15.7 Comparative Example 4 21.3 15.5 Comparative Example 5 19.5 15.6

[0088] The larger the melt index, the better the processing fluidity of the masterbatch, and the smaller the filter press value, the better its fluidity. As can be seen from Table 1, Examples 2 and 4 have large melt indexes and small filter press values. In both of these two formulations, when 20 parts of polypropylene are added, the calcium carbonate addition amount reaches 75 parts, indicating that when using the technical process of the present invention at a high filling calcium carbonate content, its processing fluidity is better. The production of high melt heavy calcium carbonate masterbatch is realized.

[0089] Taking Example 2 and comparing it with other comparative examples: The melt index of Example 2 is 36.8 g / 10 min, and the filter press value reaches 10.2;

[0090] Compared with the masterbatch prepared by adding untreated calcium carbonate and untreated polypropylene (Comparative Example 1), the melt index of the masterbatch prepared in Comparative Example 1 was only 16.3 g / 10 min, and the filter press value reached 18.9; compared with Comparative Example 1, the melt index of Example 2 increased by 125.7%, and the filter press value decreased by 46%.

[0091] Compared with the masterbatch prepared by adding untreated calcium carbonate (Comparative Example 2), the melt index of the masterbatch prepared in Comparative Example 2 was 17.4 g / 10 min, and the filter press value was 16.5; compared with Comparative Example 2, the melt index of Example 2 increased by 111.5%, and the filter press value decreased by 38.2%.

[0092] Compared with the masterbatch prepared by adding untreated polypropylene (Comparative Example 3), the melt index of the masterbatch prepared in Comparative Example 3 was 19.2 g / 10 min, and the filter press value was 15.7; compared with Comparative Example 3, the melt index of Example 2 increased by 91.7%, and the filter press value decreased by 35%.

[0093] Compared with the masterbatch prepared by a formulation system without adding PPA powder (Comparative Example 4), the melt index of the masterbatch prepared in Comparative Example 4 was 21.3 g / 10 min, and the filter press value was 15.5; compared with Comparative Example 4, the melt index of Example 2 increased by 72.8%, and the filter press value decreased by 34.2%.

[0094] Compared with the masterbatch prepared by a formulation system without adding antistatic agent (Comparative Example 5), the melt index of the masterbatch prepared in Comparative Example 5 was 19.5 g / 10 min, and the filter press value was 15.6; compared with Comparative Example 4, the melt index of Example 2 increased by 88.8%, and the filter press value decreased by 34.6%.

[0095] As can be seen from the above examples, the present invention provides a high melt index heavy calcium carbonate filled masterbatch and its preparation method. Through comprehensive analysis above, it can be found that by adopting the technical route and formula optimization design of the present invention, the processing fluidity of the heavy calcium carbonate polypropylene masterbatch is improved, which is of great significance.

[0096] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a high melt index heavy calcium carbonate filler masterbatch, characterized in that: The following steps are involved: Step 1), mixing heavy calcium carbonate, a dispersant and a modifier for pretreatment to obtain modified heavy calcium carbonate; Step 2), mixing the polypropylene and the modifier and performing pretreatment to obtain modified polypropylene; Step 3), the modified heavy calcium carbonate, modified polypropylene, polyethylene wax, zinc stearate, PPA powder and antistatic agent are mixed, and extruded, granulated and pelletized in sequence to obtain a high melt index heavy calcium carbonate filler masterbatch.

2. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 1, characterized in that: In step 1), the particle size of the heavy calcium carbonate is D50 of 2 μm to 3 μm, D97 of 6 μm to 8 μm, and the oil absorption value is 27 to 30 ml / 100 g; The added amount of the dispersant is 0.8-2% of the mass of the heavy calcium carbonate, and the added amount of stearic acid is 0.5-0.9% of the mass of the heavy calcium carbonate; The dispersant includes ethylene glycol, and the modifier includes stearic acid.

3. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 1 or 2, characterized in that: In step 1), the pretreatment is carried out under stirring, the stirring speed is 300-900 r / min, the pretreatment time is 10-30 min, and the pretreatment temperature is 105-120°C.

4. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 3, characterized in that: In step 2), the polypropylene is a powder; The amount of the modifier added is 4-9‰ of the mass of polypropylene; The modifier includes one or more of methyl stearate, butyl stearate, 2-hydroxystearate methyl ester, 12-hydroxystearate methyl ester and epoxy stearate octyl ester.

5. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 1 or 4, characterized in that: In step 2), the pretreatment is carried out under stirring, the stirring speed is 500-1500 r / min, the pretreatment time is 15-60 min, and the pretreatment temperature is 50-80°C.

6. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 5, characterized in that: In step 3), the addition amount of each component is, by weight, 70-80 parts of heavy calcium carbonate, 15-25 parts of modified polypropylene, 1-5 parts of polyethylene wax, 0.5-2 parts of zinc stearate, 0.05-0.2 parts of PPA powder, and 0.5-2 parts of antistatic agent; The PPA powder is a mixture of vinylidene fluoride, hexafluoropropylene copolymer and synthetic ester.

7. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 1 or 6, characterized in that: In step 3), the antistatic agent is a nonionic antistatic agent; The nonionic antistatic agent includes fatty acid polyol ester and / or polyethylene oxide.

8. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 7, characterized in that: In step 3), the mixing is carried out under stirring, the stirring speed is 250-500 r / min, the stirring time is 10-40 min, and the stirring temperature is 70-100°C.

9. The method for preparing a high melt index heavy calcium carbonate filler masterbatch according to claim 8, characterized in that: In step 3), the extrusion temperature is 200-240°C.

10. A high melt index heavy calcium carbonate filler masterbatch prepared by the preparation method according to any one of claims 1 to 9.