CN111662520A - Hollow spiral pipe and preparation method thereof - Google Patents

Abstract

The invention provides a hollow spiral tube and a preparation method thereof, wherein the hollow spiral tube is composed of the following raw materials in parts by weight: 150 parts of resin; 30-45 parts of carboxyl butyronitrile rubber powder; 50 parts of light calcium carbonate and 50 parts of 800-mesh heavy calcium carbonate; 0.3-0.5 part of stearic acid; 0.1-0.4 part of PE wax; CPE 8.0-8.5 shares; 5.3 parts of a calcium zinc stabilizer; 1.4-1.5 parts of titanium dioxide and 10-12 parts of whitening agent. Through the preparation procedures of raw material mixing, plasticizing granulation, blank extrusion and vacuum cooling molding, the carboxyl butyronitrile rubber powder with a core-shell structure and resin are physically crosslinked, the relation between molecular chains is effectively increased, the toughness of the material is improved, the fracture elongation of a hollow tube is improved to 45%, the tensile yield stress is improved to 21Mpa, and the longitudinal shrinkage is reduced to 3.0%. Compared with the existing pipe in the market, the calcium-zinc stabilizer has excellent chemical stability, and simultaneously, the environment-friendly calcium-zinc stabilizer replaces a lead salt stabilizer containing heavy metal, so that the influence on the environment when the lead salt stabilizer is used is reduced.

Description

Hollow spiral pipe and preparation method thereof

Technical Field

The invention belongs to the technical field of PVC (polyvinyl chloride) pipe production, and particularly relates to a hollow spiral pipe and a preparation method thereof.

Background

The PVC pipe in China is developed quickly, the annual growth rate reaches 8%, and the annual demand growth rate is 2%. Among plastic pipes, the PVC pipe has a long-distance leading use level, and is widely applied to water supply and drainage pipelines. At present, PVC pipe production mostly continues to use production methods in the 90 s, the used materials for manufacturing plastic pipes are divided into two types, one type is made of PVC and common calcium carbonate as main raw materials, the manufactured pipes have high cost, and other properties such as strength, toughness, corrosion resistance, heat resistance and other physical and chemical properties are common; the other is that the PVC pipe is prepared by using recycled PVC and calcium carbonate as main raw materials, although the manufactured pipe has low cost, the produced PVC pipe has the advantages of no white color, rough inner and outer smoothness, poor physical and chemical properties such as strength, toughness, corrosion resistance, heat resistance and the like, and poor impact resistance, freezing resistance, high temperature resistance and the like.

Meanwhile, the domestic lead salt stabilizer is the most commonly used heat stabilizer in the processing and production of PVC drainage pipe fittings at present, but belongs to harmful and toxic dangerous goods. This results in the PVC drain pipe member containing toxic and harmful elements.

The PVC drainage pipe fitting is used as an important passage for draining stagnant water. The toxic and harmful elements contained in the paint can be slowly separated out with the lapse of time. Wherein, once the migratory element lead in the stabilizer is separated out, the environment pollution is inevitably caused when the rain water enters rivers and soil. The prior art also has the problems that the tube contains toxic and harmful elements in the processing process, can be precipitated along with time in the use process and causes pollution to the environment. Therefore, the invention of the novel calcium zinc stabilizer PVC pipe fitting and the preparation method thereof is very necessary.

In view of the above, there is a need to provide a new modified PVC hollow spiral pipe, which can improve the toughness of the pipe, improve the elongation at break and tensile strength of the PVC pipe, and reduce the pollution of heavy metal precipitation to the environment by improving the calcium zinc stabilizer.

Disclosure of Invention

Aiming at the problems existing in the prior technical scheme, the invention aims to provide a hollow spiral pipe and a preparation method thereof, which can improve the fracture elongation rate and tensile strength of the pipe and enhance the toughness, and simultaneously improve the calcium-zinc stabilizer in the prior art, thereby solving the problems that the pipe contains toxic and harmful elements in the processing process, and the precipitation is increased along with time in the using process to pollute the environment in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

a hollow spiral pipe is composed of the following raw materials in parts by weight:

150 parts of resin;

30-45 parts of carboxyl butyronitrile rubber powder;

50 parts of light calcium carbonate and 50 parts of 800-mesh heavy calcium carbonate;

0.3-0.5 part of stearic acid;

0.1-0.4 part of PE wax;

CPE 8.0-8.5 shares;

5.3 parts of a calcium zinc stabilizer;

1.4-1.5 parts of titanium dioxide and 10-12 parts of whitening agent.

Further, the hollow spiral pipe is composed of the following raw materials in parts by weight:

150 parts of resin;

35 parts of carboxyl butyronitrile rubber powder;

50 parts of light calcium carbonate and 50 parts of 800-mesh heavy calcium carbonate;

0.5 part of stearic acid;

0.3 part of PE wax;

CPE 8.5 parts;

5.3 parts of a calcium zinc stabilizer;

1.4 parts of titanium dioxide and 12 parts of whitening agent.

Furthermore, Pb in the calcium-zinc stabilizer is less than or equal to 0.009 wt%, Cr6+ is less than or equal to 0.0075 wt%, Cd is less than or equal to 0.0005 wt%, Hg is less than or equal to 0.006 wt%, and the static heat stabilization time is not less than 18 minutes and the color is not changed.

Further, the whiteness of the light calcium carbonate is not less than 92; the volume average particle size is less than or equal to 3.0; PH (10% suspension) 8.0 to 10.0; the activation degree is ≧ 96.

Furthermore, the carboxyl nitrile rubber powder is in a core-shell structure, wherein the core is nitrile rubber, and the shell is a plastic carboxyl unsaturated hydrocarbon polymer.

Further, the preparation method of the carboxyl butyronitrile rubber powder comprises the following steps: copolymerizing butadiene and acrylonitrile by an emulsion copolymerization method, then adding unsaturated hydrocarbon containing carboxyl, grafting into powder by a suspension grafting method, and then washing, drying and crushing to obtain the modified butadiene-acrylonitrile copolymer; wherein, the unsaturated hydrocarbon containing carboxyl is at least one of acrylic acid, crotonic acid and methacrylic acid.

Further, the whitening agent is 2,2- (4, 4-distyryl) dibenzoxazole.

A method for preparing the hollow spiral pipe, which comprises the following steps:

the method comprises the following steps: mixing the raw materials, weighing the raw materials according to the proportion, putting the raw materials into a material jar of a high-low temperature mixer, carrying out high-temperature mixing, taking out the high-temperature mixture into a cold jar when the temperature of the mixture in the hot jar reaches 120-130 ℃, and discharging the mixed material when the temperature of the mixture in the cold jar is reduced to 40-50 ℃ to prepare the mixture for later use;

step two: plasticizing and granulating, namely putting the mixture discharged in the step one into a granulator, wherein the rotating speed of a main machine of the granulator is 30 revolutions per minute, the temperature of a charging barrel zone of the granulator is 180-190 ℃, and the temperature of a granulating die is 200-210 ℃ to prepare granules with the particle size of 1.5 mm;

step three: extruding a pipe blank, namely feeding the granular material prepared in the step two into a double-screw extruder when the temperature of the granular material is reduced to 40-50 ℃, wherein the rotating speed of an extrusion screw is 25 revolutions per minute, the rotating speed of a feeding screw is 55 revolutions per minute, the temperature of an extrusion area is 160 plus materials, the torque of the screw is 43 N.m, and the pipe blank is extruded;

step four: and (3) carrying out vacuum cooling molding on the pipe, immediately sizing and cooling the pipe blank when the pipe blank is extruded out of the die, putting the extruded pipe blank into a vacuum molding cooling box, and molding the blank by adopting an internal pressure external sizing method to prepare the molded hollow spiral pipe.

The raw materials are selected and combined, so that the effects of the raw materials generate a synergistic effect, the tensile strength, the hardness, the impact resistance and the fracture elongation of the product can be effectively improved, and the functional effects of the raw materials are as follows:

resin: the resin is a plastic assistant with dual functions of impact resistance modification and processing modification, and the PVC product has excellent impact resistance, low-temperature toughness, compatibility with PVC, weather resistance, stability and processability due to the core/shell structure, and moderate performance to price ratio, so that the fluidity and thermal deformation of PVC melt can be obviously improved, the plasticization is promoted, and the surface of the product is smooth and attractive.

Titanium dioxide: the PVC composite material is applied to the PVC drainage pipe industry, and can effectively improve the heat resistance, light resistance and weather resistance of the PVC pipe, improve the physical and chemical properties of the PVC pipe, enhance the color of the PVC pipe and prolong the service life of the PVC pipe.

Calcium carbonate: the filler is applied to the PVC drainage pipe industry, can ensure that the surface performance of the pipe is good, improve the formability of the pipe, ensure that the pipe is easy to shape, and can reduce the cost.

The raw materials all belong to the existing perfect technology, and the invention adds the following formula raw materials on the basis of the raw materials, and the functions and the effects of the raw materials are as follows:

the carboxyl nitrile rubber powder is in a core-shell structure, wherein the core is nitrile rubber, and the shell is a plastic carboxyl unsaturated hydrocarbon polymer.

The carboxyl butyronitrile rubber powder with the core-shell structure has obvious interface effect, the active surface strongly adsorbs molecular chains of a PVC matrix, and usually, a plurality of molecular chains are connected on the surface of one particle to form physical crosslinking among chains. The particles with adsorbed molecular chains can play a role in uniformly distributing load, and reduce the possibility of breaking the polymer. On the other hand, the PVC resin has a microphase separation structure on the microscopic scale, hard segment molecules are strongly associated together to form a plurality of microdomains to be dispersed in a soft segment phase matrix, the soft segment phase provides elasticity, and the hard segment phase plays a role in reinforcing filling and crosslinking. PVC is a linear polymer formed by connecting VCM monomers in a head-tail structure, and more hydrogen bonds can be formed between-COOH carried on the shell of carboxyl nitrile rubber powder particles and PVC groups, so that the binding force between the particles and a matrix is increased. When a small amount of carboxyl butyronitrile rubber powder is added, the nano-scale particles serve as hard segments and serve as a part of physical crosslinking points to effectively increase the relation among molecular chains, and when external force is applied, the nano-scale particles serve as stress concentrators to induce a large amount of silver lines and shear bands, absorb energy, control and stop the silver line development by the rubber powder particles and the shear bands, so that the silver lines are prevented from forming destructive cracks, and the enhancement and toughening are realized.

Pb in the calcium-zinc stabilizer is less than or equal to 0.009 wt%, Cr6+ is less than or equal to 0.0075 wt%, Cd is less than or equal to 0.0005 wt%, Hg is less than or equal to 0.006 wt%, and the heavy metal content is controlled within an extremely low range.

The pipe prepared from the raw materials has excellent chemical stability, effectively improves the tensile strength, impact resistance and fracture elongation of the product, and is environment-friendly and pollution-free.

Compared with the prior art, the invention has the beneficial effects that: the hollow coil pipe provided by the invention has the advantages that the carboxyl butyronitrile rubber powder with a core-shell structure and the resin are physically crosslinked, the relation between molecular chains is effectively increased, the toughness of the material is improved, the fracture elongation of the hollow pipe is improved to 45%, the tensile yield stress is improved to 21Mpa, and the longitudinal retraction rate is reduced to 3.0%. The calcium zinc stabilizer has stronger thermal shock resistance and lower thermal deformation rate, has excellent chemical stability compared with the prior pipe in the market, and simultaneously, the environment-friendly calcium zinc stabilizer replaces a lead salt stabilizer containing heavy metal, thereby reducing the influence on the environment when the lead salt stabilizer is used.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments.

Examples of the calcium zinc stabilizer are selected from the group consisting of BAEROSTAB CT 303TX, model number of Kunrui chemical Co., Ltd. The whitening agent is 2,2- (4, 4-distyryl) dibenzoxazole.

Example 1

The embodiment provides a hollow spiral pipe.

The preparation process comprises the following steps:

step one, preparing raw materials,

prepared according to the following dosage:

150kg of resin;

45kg of carboxyl butyronitrile rubber powder;

50kg of light calcium carbonate and 50kg of 800-mesh heavy calcium carbonate;

0.5kg of stearic acid;

0.4kg of PE wax;

CPE 8.5kg；

5.3kg of calcium zinc stabilizer;

1.5kg of titanium dioxide and 10kg of whitening agent.

Secondly, putting the prepared raw materials into a high-speed heating mixer (model GRH-3000) for high-speed kneading, and raising the temperature of the raw materials to 120 ℃; cooling the hot mixed and kneaded raw materials in a cooling mixer (model LH-500B) to reduce the temperature of the raw materials to below 40 ℃, and discharging for later use;

plasticizing and granulating, namely putting the mixture discharged in the step two into a granulator, wherein the rotating speed of a main machine of the granulator is 30 revolutions per minute, the temperature of a charging barrel zone of the granulator is 180-190 ℃, and the temperature of a granulating die is 200-210 ℃ to prepare granules with the particle size of 1.5 mm;

step four, extruding:

the above cooled and granulated raw materials were fed into a DAT-85 constant diameter twin screw extruder (DAE-AMICHENRYCO. LTD, Korea) and extruded, and the melt was fed into a phi 110X 3.2mm composite die from a skin feed port 9 to form inner and outer skins, under the process conditions:

the rotating speed of the main machine is as follows: 25rpm, auxiliary machine rotation speed: 34rpm, the torque of the screw is 43 N.m;

step five, cooling and vacuum-shaping the obtained semi-hose;

sixthly, code spraying and printing;

step seven, traction;

step eight, cutting;

and step nine, obtaining a finished product after inspection.

Example 2

Weighing the following raw materials in parts by weight: 150kg of resin;

30kg of carboxyl butyronitrile rubber powder;

50kg of light calcium carbonate and 50kg of 800-mesh heavy calcium carbonate;

0.3kg of stearic acid;

0.1kg of PE wax;

CPE 8.0kg；

5.3kg of calcium zinc stabilizer;

1.4kg of titanium dioxide and 10kg of whitening agent. The method for manufacturing the hollow spiral tube is the same as in example 1.

Example 3

Weighing the following raw materials in parts by weight: 150kg of resin;

35kg of carboxyl butyronitrile rubber powder;

50kg of light calcium carbonate and 50kg of 800-mesh heavy calcium carbonate;

0.5kg of stearic acid;

0.3kg of PE wax;

CPE 8.5kg；

5.3kg of calcium zinc stabilizer;

1.4kg of titanium dioxide and 12kg of whitening agent. The method for manufacturing the hollow spiral tube is the same as in example 1.

Comparative example 1

In this example, the following raw materials are weighed in parts by weight: 150kg of resin;

50kg of light calcium carbonate and 50kg of 800-mesh heavy calcium carbonate;

0.5kg of stearic acid;

0.3kg of PE wax;

CPE 8.5kg；

5.3kg of calcium zinc stabilizer;

1.4kg of titanium dioxide and 12kg of whitening agent. The preparation method is basically the same as that of the embodiment 1, and the only difference is that the additive of the carboxyl nitrile rubber powder is eliminated in the embodiment.

Physical property tests were conducted on the hollow spiral pipes obtained in examples 1 to 3, and the results are shown in table 1, and for comparison, the hollow spiral pipes of comparative example were subjected to the same tests. The hollow spiral tubes of the examples and comparative examples had an average outer diameter of 110.2 to 110.3 mm and an average wall thickness of 5.5 mm. The appearance is smooth and has no bubbles and other defects.

Table 1: physical property test results of the hollow spiral tubes of examples 1 to 3 and comparative example:

physical Properties	Test standard	Example 1	Example 2	Example 3	Comparative example 1
						Tensile yield stress Mpa	GB/T1040	22.5	25.3	23.1	16.2
Elongation at break%	GB/T1040	45.6	46.5	46.2	32
						Tear Strength N/mm	GB/T529	560	520	566	480
Vicat softening temperature (. degree. C.)	GB/T33608	80.6	81.5	80.4	76.4
						Longitudinal shrinkage%	GB/T33608	3.0	2.8	3.1	4.8
Flame retardancy	GB/UL94	V-0	V-0	V-0	V-1

Through performance tests, the hollow spiral tube provided by the invention has the advantages that the carboxyl butyronitrile rubber powder with a core-shell structure and the PVC resin are physically crosslinked, the relation between molecular chains is effectively increased, the toughness of the material is improved, the fracture elongation of the solid-wall tube is improved to 45%, the tensile yield stress is improved to 21Mpa, and the longitudinal shrinkage is reduced to 3.0%.

The materials of examples 1 to 3 and of the comparative example were subjected to impact and ageing tests, in particular, these materials were aged in an air oven at a temperature of 135 ℃ and a time of ageing of 168 hours, and then tested for mechanical properties: the low-temperature bending properties (temperature of-40 ℃ C., time of 16 hours), thermal shock resistance (temperature of 150 ℃ C., time of 1 hour) and heat distortion properties (150 ℃ C.), the results obtained are shown in Table 2:

table 2: results of the material aging property test of examples 1 to 3 and comparative example:

therefore, the composite material has the advantages of high tensile property (tensile yield stress is more than 21MPa), high tear strength (more than 500N/m), small thermal deformation (less than 2%), stronger thermal shock resistance and lower thermal deformation rate, excellent chemical stability compared with the pipe on the market of the existing comparative example, effectively improved tensile strength, hardness, impact resistance and fracture elongation rate of the product, less possibility of cracks, higher hardness and impact resistance than the existing pipe, and long service life.

Meanwhile, the invention is a significant improvement over the prior art in that the heavy metals Pb, Cr6+, Cd and Hg in the calcium-zinc stabilizer are controlled to be Pb less than or equal to 0.009 wt%, Cr6+ less than or equal to 0.0075 wt%, Cd less than or equal to 0.0005 wt%, and Hg less than or equal to 0.006 wt%, and the lead salt stabilizer containing heavy metals is replaced by the environment-friendly calcium-zinc stabilizer, so that the influence on the environment when the lead salt stabilizer is used is reduced.

The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the present invention as defined in the accompanying claims.

Claims (8)

1. The hollow spiral pipe is characterized by comprising the following raw materials in parts by weight:

150 parts of resin;

30-45 parts of carboxyl butyronitrile rubber powder;

50 parts of light calcium carbonate and 50 parts of 800-mesh heavy calcium carbonate;

0.3-0.5 part of stearic acid;

0.1-0.4 part of PE wax;

CPE 8.0-8.5 shares;

5.3 parts of a calcium zinc stabilizer;

1.4-1.5 parts of titanium dioxide and 10-12 parts of whitening agent.

2. The hollow spiral pipe as claimed in claim 1, wherein the hollow spiral pipe is composed of the following raw materials in parts by weight:

150 parts of resin;

35 parts of carboxyl butyronitrile rubber powder;

50 parts of light calcium carbonate and 50 parts of 800-mesh heavy calcium carbonate;

0.5 part of stearic acid;

0.3 part of PE wax;

CPE 8.5 parts;

5.3 parts of a calcium zinc stabilizer;

1.4 parts of titanium dioxide and 12 parts of whitening agent.

3. A hollow spiral pipe according to claim 1 or 2, wherein the calcium-zinc stabilizer contains Pb not more than 0.009 wt%, Cr6+ not more than 0.0075 wt%, Cd not more than 0.0005 wt%, Hg not more than 0.006 wt%, and does not change color with static heat stabilization time not less than 18 minutes.

4. A hollow spiral pipe according to claim 1 or 2, wherein the light calcium carbonate has a whiteness of 92 or more; the volume average particle size is less than or equal to 3.0; PH (10% suspension) 8.0 to 10.0; the activation degree is ≧ 96.

5. A hollow spiral hose according to claim 1 or 2, wherein the carboxylated nitrile rubber powder has a core-shell structure, wherein the core is nitrile rubber and the shell is a plastic carboxylated unsaturated hydrocarbon polymer.

6. A hollow spiral tube as claimed in claim 5, wherein the preparation method of the carboxyl nitrile rubber powder is as follows: copolymerizing butadiene and acrylonitrile by an emulsion copolymerization method, then adding unsaturated hydrocarbon containing carboxyl, grafting into powder by a suspension grafting method, and then washing, drying and crushing to obtain the modified butadiene-acrylonitrile copolymer; wherein, the unsaturated hydrocarbon containing carboxyl is at least one of acrylic acid, crotonic acid and methacrylic acid.

7. A hollow spiral pipe as claimed in claim 1 or 2, wherein the whitening agent is 2,2- (4, 4-distyryl) bisbenzoxazole.

8. A method for manufacturing a hollow spiral pipe as claimed in any one of claims 1 to 7, comprising the steps of:

the method comprises the following steps: mixing the raw materials, weighing the raw materials according to the proportion, putting the raw materials into a material jar of a high-low temperature mixer, carrying out high-temperature mixing, taking out the high-temperature mixture into a cold jar when the temperature of the mixture in the hot jar reaches 120-130 ℃, and discharging the mixed material when the temperature of the mixture in the cold jar is reduced to 40-50 ℃ to prepare the mixture for later use;

step two: plasticizing and granulating, namely putting the mixture discharged in the step one into a granulator, wherein the rotating speed of a main machine of the granulator is 30 revolutions per minute, the temperature of a charging barrel zone of the granulator is 180-190 ℃, and the temperature of a granulating die is 200-210 ℃ to prepare granules with the particle size of 1.5 mm;

step three: extruding a pipe blank, namely feeding the granular material prepared in the step two into a double-screw extruder when the temperature of the granular material is reduced to 40-50 ℃, wherein the rotating speed of an extrusion screw is 25 revolutions per minute, the rotating speed of a feeding screw is 55 revolutions per minute, the temperature of an extrusion area is 160 plus materials, the torque of the screw is 43 N.m, and the pipe blank is extruded;

step four: and (3) carrying out vacuum cooling molding on the pipe, immediately sizing and cooling the pipe blank when the pipe blank is extruded out of the die, putting the extruded pipe blank into a vacuum molding cooling box, and molding the blank by adopting an internal pressure external sizing method to prepare the molded hollow spiral pipe.