CN112300486A - Low-odor high-fluidity polypropylene with long electret efficiency - Google Patents

Abstract

The invention discloses a polypropylene with low odor, high fluidity and long electret efficiency, which comprises the following raw materials in percentage by weight: 94.95-97.85% of polypropylene resin powder; 0.2-0.5% of peroxide initiator; 0.05-0.15% of antioxidant; 0.05-0.1% of a lubricant; 1-2% of a softener; 0.05-0.5% of nucleating agent; 0.3-0.8% of an electret; 0.5-1% of molecular weight regulator. The invention has low odor, high fluidity, long-term electret efficiency and low charge decay rate, and the cloth surface of the prepared melt-blown cloth is soft.

Description

Low-odor high-fluidity polypropylene with long electret efficiency

Technical Field

The invention relates to the technical field of melt-blown material production, in particular to polypropylene with low odor, high fluidity and long electret efficiency.

Background

With the development of economic society, people put forward higher and higher requirements on environmental quality, and pay more and more attention to health protection. In recent years, people have gradually developed the habit of wearing protective articles in public places in the haze weather and the frequent occurrence of infectious diseases. The mask generally has three layers, wherein the inner layer and the outer layer are both made of non-woven fabrics, the middle filter layer (M layer) is melt-blown cloth which is used as a filter layer of the mask and is a heart in the SMS (short message service) of the medical mask. The physical filtration and the electrostatic adsorption of the mask can reach more than 95 percent of filtration performance by melt-blown spinning and electret treatment. As a raw material of melt-blown cloth, the melt-blown cloth is high-fluidity polypropylene which has good fluidity, fast mold filling, low energy consumption and high production efficiency, and is concerned by people for a long time. At present, manufacturers for producing the special melt-blown materials abroad include Exxon-mobile, Basell, Borealis, Dow, BP-AMOCO and the like; the method is characterized by comprising medium petrochemical industry, Yanshan petrochemical industry, Yanzi petrochemical industry, Jinfa technology, Don group and the like. Although manufacturers such as bamboo shoots in the spring after rain, the horizontal residuals are uneven.

The preparation of high-fluidity polypropylene usually has two methods, one is to adopt a novel catalyst and use hydrogen to adjust the molecular weight and the distribution of the polypropylene in the polymerization process, and directly synthesize the high-fluidity polypropylene in a polymerization kettle, but the method has extremely high requirements on condition control, and is difficult to produce the polypropylene with narrow relative molecular weight distribution and high fluidity. The other is the controlled degradation of polypropylene by adding organic peroxide to polypropylene base resin, thereby improving the fluidity of the resin, which is also called controlled rheology technology. The technology adopts organic peroxide to break the high molecular chain in the polypropylene resin, so that the molecular weight distribution of the resin is narrowed, and the fluidity is greatly improved. The technical reaction is easy to control, the equipment investment is low, and the method becomes a research hotspot in recent years.

With the global spread of the Covid-19 epidemic at the end of 2019, the demand of global medical masks and civil masks is increased dramatically. The high fluidity polypropylene has the rising price of water with the sharp increase of market demand, so that low-end melt-blown materials are abused in the low-end melt-blown fabric market, the filtration effect is poor, the air resistance is large, and the smell is heavy. The secondary residue of peroxide enters a single screw of the non-woven fabric to continue reacting, or after the processing temperature is too high, the interior of PP has a secondary crystallization rearrangement process, so that the melt-blown fabric becomes brittle and hard and cannot be used; the charge-holding master batch is prepared by using organic fluorocarbon polymer mostly, and the charge decay speed of the charge-holding master batch is faster than that of inorganic tourmaline.

Disclosure of Invention

The invention aims to provide polypropylene with low odor, high fluidity and long electret efficiency.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the polypropylene with low odor, high fluidity and long electret efficiency comprises the following raw materials in percentage by weight:

94.95-97.85% of polypropylene resin powder;

0.2-0.5% of peroxide initiator;

0.05-0.15% of antioxidant;

0.05-0.1% of a lubricant;

1-2% of a softener;

0.05-0.5% of nucleating agent;

0.3-0.8% of an electret;

0.5-1% of molecular weight regulator.

The polypropylene resin powder is homopolymerized polypropylene with a melt index of 25-40 g/10 min.

The peroxide initiator is one of di-tert-butylperoxyisopropyl benzene, DCP, 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane and di-tert-butylperoxide; the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, TNPP and antioxidant DLTDP.

The lubricant is one or two of a fluoropolymer processing aid PPA or magnesium stearate.

The softener is one of hydrogenated polystyrene block copolymer, Exxon POE8780, Exxon POE8880 and a softening master batch. In the invention, the softener is particularly added in the processing of the high-melt index polypropylene material, so that the risk of embrittling the cloth surface due to the recrystallization of PP after the melt-blown cloth is cooled is effectively reduced.

The preparation method of the soft master batch comprises the following steps: 50 parts of homopolymerized polypropylene resin powder, 50 parts of Exxon POE8780 and 0.05 part of antioxidant 1010, mixing and extruding the mixture by using a double screw rod, stretching the mixture into strips, carrying out water-cooling granulation, screening the strips by using a vibrating screen, and drying the strips in a drying bin to obtain the polypropylene resin. The invention adopts the specific soft master batch to carry out secondary processing on the Exxon POE8780, improves the compatibility and the dispersibility of the master batch in PP, and obviously slows down the charge decay rate.

The nucleating agent is one of rigidity-increasing nucleating agent, sorbitol nucleating agent (MDBS, CDBS, EDBS) and organic phosphate nucleating agent. Nucleating agents can assist in reducing the rate of charge decay.

The electret is zinc oleate modified tourmaline powder, and the preparation method of the zinc oleate modified tourmaline powder comprises the following steps: mixing 100 parts by weight of 80-100 nm tourmaline powder with 80-120 parts by weight of 5-8% zinc oleate ethanol solution at the rotating speed of 80-100rpm for 30-60min, and drying under vacuum reduced pressure to obtain the product. Tourmaline is praised as an always-on charge material, and can easily agglomerate and is not easily mixed with polypropylene due to the fact that tourmaline belongs to an inorganic mineral material, so that the risk of blocking spinneret holes exists. According to the invention, tourmaline powder is modified by zinc oleate, and zinc oleate can wrap tourmaline, so that self agglomeration is prevented, and meanwhile, the combination of tourmaline powder and polypropylene is improved, so that the tourmaline powder is uniformly distributed in polypropylene, and the risk of blocking spinneret plate holes is reduced. Meanwhile, zinc oleate can also inhibit bacteria and deodorize, bring certain antibacterial property to melt-blown cloth and reduce peculiar smell.

The molecular weight regulator is one of dodecyl mercaptan, CPDB, mercaptoethanol, mercaptoacetic acid, mercaptopropanol and mercaptopropionic acid. The molecular weight regulator can generate oxidation-reduction reaction with residual peroxide, consumes initiator and reduces the possibility of the melt-blown fabric becoming brittle.

A preparation method of polypropylene with low odor, high fluidity and long electret efficiency comprises the following steps:

(1) weighing the polypropylene resin powder, the peroxide initiator, the antioxidant, the lubricant, the softener, the electret and the nucleating agent according to the formula ratio, adding into a high-speed mixer, and mixing for 5-8 minutes at the rotating speed of 250-400 rpm under the protection of nitrogen to obtain a mixed material;

(2) putting the mixed material into a storage bin, and putting the mixed material into a double-screw extruder for water-cooling, bracing and granulating, wherein the length-diameter ratio of the double-screw extruder is 40: 1-50: 1; the temperature of each section of the machine body of the double-screw extruder is as follows in sequence: 150 ℃ plus or minus 5 ℃, 170 ℃ plus or minus 5 ℃, 190 ℃ plus or minus 3 ℃, 240 ℃ plus or minus 3 ℃, 180 ℃ plus or minus 5 ℃ and 170 plus or minus 5rpm of twin-screw rotating speed.

The invention has the beneficial effects that: low odor, high fluidity, long-term electret efficiency, slow charge decay rate and soft cloth surface of the melt-blown cloth.

Detailed Description

The technical solution of the present invention will be further specifically described below by way of specific examples.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified.

Example 1:

the polypropylene with low odor, high fluidity and long electret efficiency comprises the following raw materials in percentage by weight:

94.95 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.5% (akusobp);

0.15% of antioxidant (a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1: 1);

0.1% lubricant (fluoropolymer processing aid PPA);

softener 2% (kraton HSBC);

nucleating agent 0.5% (sorbitol nucleating agent EDBS, commercially available);

electret 0.8% (zinc oleate modified tourmaline powder);

molecular weight regulator 1% (dodecyl mercaptan).

Example 2:

the polypropylene with low odor, high fluidity and long electret efficiency is characterized by comprising the following raw materials in percentage by weight:

97.85 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.2% (akusu DTBP);

0.05% of antioxidant (a mixture of antioxidant 1076 and 168 in a mass ratio of 1: 1);

lubricant 0.05% (magnesium stearate);

softener 1% (exxon POE 8880);

0.05% of nucleating agent (stiffening nucleating agent, commercially available);

electret 0.3% (zinc oleate modified tourmaline powder);

molecular weight regulator 0.5% (CPDB).

Example 3:

the polypropylene with low odor, high fluidity and long electret efficiency is characterized by comprising the following raw materials in percentage by weight:

97.05 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.3% (2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane);

0.08% of antioxidant (a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1: 1);

lubricant 0.07% (magnesium stearate);

softener 1.2% (exxon POE 8780);

nucleating agent 0.1% (sorbitol nucleating agent MDBS, commercially available);

electret 0.5% (zinc oleate modified tourmaline powder);

molecular weight regulator 0.7% (mercaptoethanol).

Example 4:

the difference between the embodiment and the embodiment 3 is that the softener is replaced by the softener master batch.

Comparative example 1

The polypropylene with low odor, high fluidity and long electret efficiency comprises the following raw materials in percentage by weight:

94.75 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.5% (akusobp);

0.15% of antioxidant (a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1: 1);

0.1% lubricant (fluoropolymer processing aid PPA);

softener 2% (kraton HSBC);

nucleating agent 0.5% (sorbitol nucleating agent EDBS, commercially available);

electret 1% (zinc oleate modified tourmaline powder);

molecular weight regulator 1% (dodecyl mercaptan).

Comparative example 2:

the polypropylene with low odor, high fluidity and long electret efficiency comprises the following raw materials in percentage by weight:

96.95 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.5% (akusobp);

0.15% of antioxidant (a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1: 1);

0.1% lubricant (fluoropolymer processing aid PPA);

nucleating agent 0.5% (sorbitol nucleating agent EDBS, commercially available);

electret 0.8% (zinc oleate modified tourmaline powder);

molecular weight regulator 1% (dodecyl mercaptan).

Comparative example 3:

the polypropylene with low odor, high fluidity and long electret efficiency is characterized by comprising the following raw materials in percentage by weight:

98.85 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.2% (akusu DTBP);

0.05% of antioxidant (a mixture of antioxidant 1076 and 168 in a mass ratio of 1: 1);

lubricant 0.05% (magnesium stearate);

0.05% of nucleating agent (stiffening nucleating agent, commercially available);

electret 0.3% (zinc oleate modified tourmaline powder);

molecular weight regulator 0.5% (CPDB).

Comparative example 4

The polypropylene with low odor, high fluidity and long electret efficiency is characterized by comprising the following raw materials in percentage by weight:

98.25 percent of polypropylene resin powder (melt index is 40g/10 min);

peroxide initiator 0.3% (2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane);

0.08% of antioxidant (a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1: 1);

lubricant 0.07% (magnesium stearate);

nucleating agent 0.1% (sorbitol nucleating agent MDBS, commercially available);

electret 0.5% (zinc oleate modified tourmaline powder);

molecular weight regulator 0.7% (mercaptoethanol).

The preparation method of the zinc oleate modified tourmaline powder comprises the following steps: mixing 100 parts by weight of 80-100 nm tourmaline powder with 80-120 parts by weight of 5-8% zinc oleate ethanol solution at the rotating speed of 80-100rpm for 30-60min, and drying under vacuum reduced pressure to obtain the product.

The preparation method comprises the following steps:

(1) weighing the polypropylene resin powder, the peroxide initiator, the antioxidant, the lubricant, the softener, the electret and the nucleating agent according to the formula ratio, adding into a high-speed mixer, and mixing for 5-8 minutes at the rotating speed of 250-400 rpm under the protection of nitrogen to obtain a mixed material;

(2) putting the mixed material into a storage bin, and putting the mixed material into a double-screw extruder for water-cooling, bracing and granulating, wherein the length-diameter ratio of the double-screw extruder is 40: 1-50: 1; the temperature of each section of the machine body of the double-screw extruder is as follows in sequence: 150 ℃ plus or minus 5 ℃, 170 ℃ plus or minus 5 ℃, 190 ℃ plus or minus 3 ℃, 240 ℃ plus or minus 3 ℃, 180 ℃ plus or minus 5 ℃ and 170 plus or minus 5rpm of twin-screw rotating speed.

The products of examples 1-4 and comparative examples 1-4 were tested and the results are shown in the following table:

。

and (4) conclusion: the data of comparative example 3 and example 4 show that when the softener is replaced by the exxon POE8780, namely the modified exxon POE8780, the compatibility and the dispersibility of the POE8780 in PP are improved, the charge decay rate is obviously slowed down, and the effect is obvious. From examples 1-3, there is no significant difference in the gradual increase of ash in the product as the electret content increases, however, when the electret content increases from 0.8% to 1% (comparative example 1 and comparative example 1), the ash in the product increases significantly, increasing the risk of clogging of the spinneret, and thus, the electret content is strictly controlled below 1%. Comparison of comparative examples 2-4 with examples 1-3 shows that cloth surfaces without softener are hard and brittle, which seriously affects performance.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.

Claims (10)

1. The polypropylene with low odor, high fluidity and long electret efficiency is characterized by comprising the following raw materials in percentage by weight:

94.95-97.85% of polypropylene resin powder;

0.2-0.5% of peroxide initiator;

0.05-0.15% of antioxidant;

0.05-0.1% of a lubricant;

1-2% of a softener;

0.05-0.5% of nucleating agent;

0.3-0.8% of an electret;

0.5-1% of molecular weight regulator.

2. The polypropylene of claim 1, wherein the polypropylene resin powder is a homopolypropylene with a melt index of 25-40 g/10 min.

3. The polypropylene of claim 1, wherein the peroxide initiator is one of bis (t-butylperoxy isopropyl benzene), DCP, 2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane, di-t-butyl peroxide; the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, TNPP and antioxidant DLTDP.

4. The polypropylene of claim 1, wherein the lubricant is one or both of a fluoropolymer processing aid PPA or magnesium stearate.

5. The polypropylene of claim 1, wherein the softener is one of hydrogenated polystyrene block copolymer, Exxon POE8780, Exxon POE8880, and softener masterbatch.

6. The polypropylene of claim 1, wherein the method for preparing the soft masterbatch comprises: 50 parts of homopolymerized polypropylene resin powder, 50 parts of Exxon POE8780 and 0.05 part of antioxidant 1010, mixing and extruding the mixture by using a double screw rod, stretching the mixture into strips, carrying out water-cooling granulation, screening the strips by using a vibrating screen, and drying the strips in a drying bin to obtain the polypropylene resin.

7. The polypropylene of claim 1, wherein the nucleating agent is one of a stiffening nucleating agent, a sorbitol nucleating agent, and an organophosphate nucleating agent.

8. The polypropylene with low odor and high fluidity and long electret efficiency as claimed in claim 1, wherein the electret is zinc oleate modified tourmaline powder, and the preparation method of the zinc oleate modified tourmaline powder comprises the following steps: mixing 100 parts by weight of 80-100 nm tourmaline powder with 80-120 parts by weight of 5-8% zinc oleate ethanol solution at the rotating speed of 80-100rpm for 30-60min, and drying under vacuum reduced pressure to obtain the product.

9. The polypropylene of claim 1, wherein the molecular weight modifier is one of dodecyl mercaptan, CPDB, mercaptoethanol, thioglycolic acid, mercaptopropanol, and mercaptopropionic acid.

10. The polypropylene of claim 1, which is prepared by the following steps:

(1) weighing the polypropylene resin powder, the peroxide initiator, the antioxidant, the lubricant, the softener, the electret and the nucleating agent according to the formula ratio, adding into a high-speed mixer, and mixing for 5-8 minutes at the rotating speed of 250-400 rpm under the protection of nitrogen to obtain a mixed material;

(2) putting the mixed material into a storage bin, and putting the mixed material into a double-screw extruder for water-cooling, bracing and granulating, wherein the length-diameter ratio of the double-screw extruder is 40: 1-50: 1; the temperature of each section of the machine body of the double-screw extruder is as follows in sequence: 150 ℃ plus or minus 5 ℃, 170 ℃ plus or minus 5 ℃, 190 ℃ plus or minus 3 ℃, 240 ℃ plus or minus 3 ℃, 180 ℃ plus or minus 5 ℃ and 170 plus or minus 5rpm of twin-screw rotating speed.