High-toughness polypropylene suction nozzle tube and preparation method thereof

Abstract

The invention discloses a high-toughness polypropylene suction nozzle tube and a preparation method thereof, and relates to the technical field of polypropylene materials. The method comprises the following steps: firstly, co-grafting modification of maleic anhydride and siloxane is carried out on a polypropylene matrix, pre-crosslinking treatment is carried out on a composite elastomer, and meanwhile, organic intercalation is carried out on montmorillonite; then, the three components are subjected to melt blending with auxiliary agents such as polyether amine and epoxy silsesquioxane, a rigid nanosheet-elastomer microcell synergistic enhancement structure is constructed through in-situ chemical bonding of a multi-phase interface, and a flexible bridging interface layer is introduced to eliminate stress concentration. And finally, performing injection molding and heat treatment to obtain a finished product. The polypropylene suction nozzle tube prepared by the invention has excellent mechanical toughness.

Description

Technical Field

[0001] This invention relates to the field of polypropylene material technology, specifically to a high-toughness polypropylene nozzle and its preparation method. Background Technology

[0002] Currently, polypropylene (PP) is widely used as the base material for the spouts of flexible food packaging. It boasts advantages such as low raw material cost, excellent injection molding performance, lightweight portability, and compliance with basic hygiene requirements for food contact materials, making it the mainstream material in this field. However, polypropylene is a crystalline polymer, exhibiting significant brittleness at low temperatures. Furthermore, pure PP has limited impact resistance, resulting in significant shortcomings in practical applications: in low-temperature transportation or storage environments during winter (where ambient temperatures are often below 10°C), the spouts are prone to cracking from minor impacts or pressure, compromising the packaging seal; additionally, during the heat-sealing process between the spout and the flexible packaging bag, the spout must withstand certain thermal stress, and products with insufficient toughness are prone to cracking at the joint, reducing the yield of finished packaging. Summary of the Invention

[0003] The purpose of this invention is to provide a high-toughness polypropylene nozzle and its preparation method, so as to solve the technical problem of insufficient toughness of the nozzle mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing a high-toughness polypropylene suction tube includes the following steps:

[0006] S1. Homopolymer polypropylene, maleic anhydride, vinyltriethoxysilane, dicumyl peroxide and anti-degradation composite agent are mixed and wetted with white oil. The mixture is then subjected to high-speed mixing to obtain a premix. The premix is ​​fed into a twin-screw extruder for melt reaction extrusion to obtain co-grafted polypropylene particles.

[0007] S2. After melting and homogenizing the polyolefin elastomer and styrene-ethylene-butene-styrene block copolymer, add the premixed liquid of divinylbenzene and diisopropylbenzene peroxide, and then perform intensive mixing to obtain the pre-crosslinked composite elastomer.

[0008] S3. Dissolve hexadecyltrimethylammonium bromide in a mixed solvent of deionized water and ethanol, add sodium montmorillonite and stir at a constant temperature. After the reaction is completed, filter, wash, dry and pulverize to obtain organo-montmorillonite.

[0009] S4, mix the co-grafted polypropylene particles, the pre-crosslinked composite elastomer, the organically modified montmorillonite, the maleic anhydride grafted polyolefin elastomer, the polypropylene oxide diamine and the epoxy-functionalized silsesquioxane, wherein deionized water is pre-sprayed and adsorbed on the surface of the organically modified montmorillonite; melt blend and extrude all components in a twin-screw extruder to obtain modified polypropylene particles;

[0010] S5, after drying the modified polypropylene particles, put them into an injection molding machine to perform injection molding to obtain a nozzle tube blank; and heat treat the nozzle tube blank to obtain the high-toughness polypropylene nozzle tube.

[0011] The toughness of the nozzle tube is improved from the following aspects: on the one hand, by co-grafting maleic anhydride and vinyl siloxane active groups on the polypropylene molecular chain, the polypropylene matrix is endowed with high chemical activity, the grafting reaction process is controlled by using a low-concentration initiator, the structural rigidity of the polypropylene long chain is maximally preserved, and the imbalance between toughness and rigidity caused by excessive chain scission of the molecular chain is avoided; the active groups after grafting can provide stable interface bonding sites for subsequent elastomers and nanometer montmorillonite, reducing interface defects between phases in the subsequent blending process, laying a structural foundation for toughness improvement from the matrix level, and the stable matrix rigidity also avoids the deterioration of material support performance in the toughening process. On the other hand, the composite elastomer is first subjected to mild pre-crosslinking treatment, the semi-interpenetrating network structure formed enhances the morphological stability of the elastomer phase in high-shear blending, so that it can form uniformly distributed "elastic islands" in the polypropylene matrix, when the material is impacted by external force, these elastic microzones can absorb impact energy through their own deformation to avoid rapid crack propagation; secondly, the interlayer spacing of the organically intercalated nanometer montmorillonite is expanded, which can be directionally distributed at the interface between the polypropylene matrix and the elastomer in the blending process, the rigidity of the nanometer sheet layer can effectively transmit stress and inhibit crack initiation at the interface; finally, through in-situ chemical bonding of the multi-phase interface, a firm interface bonding force is formed between the polypropylene matrix, the elastomer microzone and the nanometer montmorillonite sheet layer, eliminating interface voids and other defects, when the material is subjected to external force, stress can be uniformly transmitted between the three phases, with the help of the deformation energy of the elastomer and the crack deflection effect of the nanometer sheet layer, the low-temperature impact toughness and elongation at break of the polypropylene nozzle tube are simultaneously improved without significantly losing rigidity.

[0012] In the experiment, although a strong chemical bonding force is built between the polypropylene matrix, the elastomer and the nanometer montmorillonite, at the microscale, this short-range and dense strong chemical anchoring brings a side effect: the molecular chain segments at the interface lose the necessary relaxation and sliding ability due to being 'rigidly locked'. This means that when the suction tube encounters an extremely low temperature (below-20 DEG C) environment or high-altitude drop and other high-speed impacts, due to the lack of a modulus buffer 'transition zone' between the rigid PP matrix and the flexible elastomer microzone, the impact energy cannot be smoothly conducted to the elastomer inside for energy consumption, but will be accumulated instantaneously on these rigid chemical bonding points, causing serious'stress concentration' and'strain hysteresis' phenomena. This causes the interface layer to be deformed before the elastomer at the moment of stress, resulting in micro-brittle peeling, which is manifested in the macroscopic as the suction tube appearing obvious'stress whitening' or even brittle cracking at the stress site, forming the technical problem that the stronger the interface bonding, the higher the low-temperature impact sensitivity, which limits the further improvement of the material toughness. The present application further solves the above technical problems by introducing a 'linear-cage hybrid interface damping system' composed of long-chain flexible polyether amine and cage-like epoxy-based silsesquioxane on the basis of the original scheme. The principle is that: the long-chain flexible conformation of polyether amine is used to build a'molecular level flexible bridge' between the PP matrix, the elastomer and the montmorillonite layer, and through the large-scale relaxation of the chain segment, a microsecond stress buffer time is provided, and at the same time, the POSS with an eight-functional nanocage structure is used as a 'topological crosslinking node' to in-situ build a'molecular level spring bed' interface layer with a modulus gradient transition feature. This synergistic mechanism not only eliminates the interface brittleness by using flexible bridging, but also assists the montmorillonite to achieve molecular level peeling and reduce the internal heat of processing through the 'nanoball' effect of POSS, realizes the essential change of the interface from 'rigid locking' to 'elastic suspension', and thus greatly improves the impact strength and stress whitening resistance in an extremely cold environment of-20 DEG C, realizes the low-temperature super toughness of the suction tube, and further improves the toughness of the polypropylene material.

[0013] Preferably, in step S1, the mass ratio of the homopolymer polypropylene to maleic anhydride is 100:(2-4).

[0014] Preferably, in step S1, the anti-degradation complexing agent is composed of hindered phenol 1010 and phosphite 168.

[0015] Preferably, in step S2, the mass ratio of the polyolefin elastomer to the styrene-ethylene-butylene-styrene block copolymer is 8:(3-5).

[0016] Preferably, in step S3, the mass ratio of the sodium-based montmorillonite to cetyltrimethylammonium bromide is 5:(1-3).

[0017] As preferred, in the step S3, the reaction temperature is 80-85℃, and the reaction time is 3-5h.

[0018] As preferred, in the step S4, the mass ratio of the co-grafted polypropylene particles to the pre-crosslinked composite elastomer is 100:(10-15).

[0019] As preferred, in the step S4, the mass ratio of the grafted polypropylene particles to the organo-modified montmorillonite is 100:(3-5).

[0020] As preferred, in the step S4, the mass ratio of the polyoxypropylene diamine to the epoxy-functionalized silsesquioxane is 6:(2-4).

[0021] A high-toughness polypropylene nozzle pipe is prepared by the above method.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1. By controllable co-grafting modification of the polypropylene matrix, firm interface bonding sites are provided for the material, and by pre-crosslinking treatment of the elastomer, the stability of the form in subsequent processing is ensured, thus laying a structural foundation for greatly improving the toughness from two aspects of the matrix and the dispersed phase.

[0024] 2. By introducing a "linear-cage hybrid interface damping system" composed of long-chain polyether amine and cage silsesquioxane, an interface layer with modulus gradient transition is formed between the rigid matrix and the flexible elastomer, thus converting the original "rigid locking" into "elastic suspension", effectively eliminating stress concentration, and significantly improving the impact resistance and stress whitening resistance of the material in extremely low temperature environment, thus realizing the low-temperature super-toughness of the nozzle pipe. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM image of the cross section of the polypropylene nozzle pipe prepared in Example 1 of the present application.

[0026] Figure 2 XPS spectrum of the polypropylene nozzle pipe prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] Example 1

[0029] A method for preparing a high-toughness polypropylene nozzle tube, comprising the following steps:

[0030] Step 1: take 100 parts of homopolymer polypropylene (melt index 3.5 g / 10 min), 3.5 parts of maleic anhydride, 1.5 parts of vinyl triethoxysilane (KH171), 0.12 parts of dicumyl peroxide (DCP), 0.4 parts of anti-degradation complexing agent (2:1 complex of hindered phenol 1010 and phosphite 168), and 0.1 parts of white oil by mass fraction. First, the homopolymer polypropylene particles are mixed and wetted with 0.1 parts of white oil at high speed, then MAH, KH171 and DCP are added, and the premix is prepared by mixing in a high-speed mixer at a speed of 850 r / min for 6 min; the premix is put into a twin-screw extruder, the feeding section is set to 150°C, the compression section is set to 175°C, the melting section is set to 190°C, the reaction section is set to 200°C, and the head section is set to 190°C, the screw speed is 220 r / min, and the vacuum exhaust is opened at the end of the extruder. Get the co-grafted polypropylene particles.

[0031] Step 2: take 8 parts of polyolefin elastomer (POE), 4.5 parts of styrene-ethylene-butylene-styrene block copolymer (SEBS), 0.2 parts of divinylbenzene (DVB), and 0.05 parts of dicumyl peroxide (DCP) by mass fraction. First, POE and SEBS are put into an internal mixer and melted and homogenized at 160°C for 2 min, then a premixed solution of DVB and DCP is added, and the speed is increased to 65 r / min for 8 min. Continuous internal mixing to obtain a pre-crosslinked composite elastomer.

[0032] Step 3: take 5 parts of sodium-based montmorillonite and 2.5 parts of cetyltrimethylammonium bromide (CTAB) by mass fraction. Dissolve CTAB completely in a mixed solvent (volume ratio 4:1) of deionized water and ethanol to prepare a 5% suspension, then add montmorillonite, and stir at a high speed of 750 r / min in a constant temperature stirred tank at 83°C for 4.5 h. After the reaction is completed, perform suction filtration, first wash the filter cake with hot ethanol at 70°C for 2 times to completely remove free quaternary ammonium salt, then repeatedly wash with deionized water until the filtrate is free of bromide ions (no turbidity) as detected by 0.1 mol / L silver nitrate; Finally, the washed montmorillonite is dried in a vacuum drying oven at 105°C to constant weight and ultra-finely ground to obtain organically modified montmorillonite;

[0033] Step 4: Take 100 parts of the co-grafted PP particles prepared in Step 1, 14 parts of the pre-crosslinked composite elastomer prepared in Step 2, 4.5 parts of the organo-montmorillonite prepared in Step 3, 3 parts of maleic anhydride grafted polyolefin elastomer (POE-g-MAH), 0.6 parts of polyoxypropylene diamine (D-2000), and 0.35 parts of epoxy-functionalized polyhedral oligomeric silsesquioxane (Epoxy-POSS) by mass fraction. To facilitate the hydrolysis of silsesquioxane, 0.02 parts of deionized water is first sprayed and adsorbed on the surface of the organo-montmorillonite before being added. All components are fed into a twin-screw extruder, with the temperature set to 160°C for the feeding section, 185°C for the compression section, 200°C for the dispersion section, and 190°C for the homogenization section, and the screw speed is 200 r / min. High vacuum exhaust (-0.09 MPa) is turned on to obtain modified polypropylene particles.

[0034] Step 5: The modified polypropylene particles are subjected to hot air circulation drying at 90°C for 5 hours, and then fed into a horizontal injection molding machine. The injection molding process is controlled as follows: the barrel gradient temperature is 185°C, 195°C, and 205°C, the nozzle temperature is 200°C, the mold temperature is controlled at 50°C to optimize the PP crystalline morphology, the injection pressure is 90 MPa, the holding pressure is 60 MPa, and the cooling and setting time is 18 seconds. The molded nozzle tube product is placed in a 85°C devolatilization oven for continuous heat treatment for 2 hours to completely remove trace amounts of benzalacetone and other odor molecules generated by DCP decomposition, obtaining a high-toughness polypropylene nozzle tube.

[0035] Example 2

[0036] A method for preparing a high-toughness polypropylene nozzle tube, comprising the following steps:

[0037] Step 1: Take 100 parts of homopolymer polypropylene (melt index 3.5 g / 10 min), 2.5 parts of maleic anhydride, 1.5 parts of vinyl triethoxysilane (KH171), 0.12 parts of dicumyl peroxide (DCP), 0.4 parts of anti-degradation complexing agent (a mixture of hindered phenol 1010 and phosphite 168 at a ratio of 2:1), and 0.1 parts of white oil by mass fraction. First, the homopolymer polypropylene particles are mixed with 0.1 parts of white oil at high speed to wet them, then the premixed MAH, KH171, and DCP are added, and the mixture is mixed in a high-speed mixer at a speed of 850 r / min for 6 minutes to prepare a premix; the premix is fed into a twin-screw extruder, with the feeding section set to 150°C, the compression section to 175°C, the melting section to 190°C, the reaction section to 200°C, and the die head section to 190°C, and the screw speed is 220 r / min. Vacuum exhaust is turned on at the end of the extruder to obtain co-grafted polypropylene particles.

[0038] Step 2: Take polyolefin elastomer (POE) 8 parts, styrene-ethylene-butylene-styrene block copolymer (SEBS) 3.5 parts, divinylbenzene (DVB) 0.2 parts, dicumyl peroxide (DCP) 0.05 parts by mass fraction. First, POE and SEBS are put into the internal mixer and melt homogenized at 160℃ for 2min, then the premixed solution of DVB and DCP is added, and the rotation speed is increased to 65r / min for 8min, to obtain a pre-crosslinked composite elastomer.

[0039] Step 3: Take sodium-based montmorillonite 5 parts, cetyltrimethylammonium bromide (CTAB) 1.5 parts by mass fraction. Dissolve CTAB completely in a mixed solvent of deionized water and ethanol (volume ratio 4:1) to prepare a 5% concentration suspension, then add montmorillonite, and stir at 83℃ for 3.5h at 750r / min in a constant temperature stirred tank. After the reaction is completed, perform suction filtration, and the filter cake is first washed with hot ethanol at 70℃ for 2 times to completely remove free quaternary ammonium salt, then washed repeatedly with deionized water until the filtrate is free of bromide ions (no turbidity) as detected by 0.1mol / L silver nitrate; finally, the washed montmorillonite is dried in a vacuum drying oven at 105℃ to constant weight and superfine pulverized, to obtain organically modified montmorillonite;

[0040] Step 4: Take the co-grafted PP particles prepared in step 1 100 parts, the pre-crosslinked composite elastomer prepared in step 2 12 parts, the organically modified montmorillonite prepared in step 3 3.5 parts, maleic anhydride grafted polyolefin elastomer (POE-g-MAH) 3 parts, polyoxypropylene diamine (D-2000) 0.6 parts, epoxy-functionalized silsesquioxane (Epoxy-POSS) 0.25 parts by mass fraction. To promote siloxane hydrolysis, first spray adsorb 0.02 parts of deionized water on the surface of the organically modified montmorillonite before feeding. Put all components into a twin-screw extruder, set the temperature to: feeding section 160℃, compression section 185℃, dispersion section 200℃, homogenization section 190℃, screw rotation speed 200r / min, and open high vacuum exhaust (-0.09MPa), to obtain modified polypropylene particles.

[0041] Step 5: Dry the modified polypropylene particles in a hot air circulation oven at 90℃ for 5h, then put them into a horizontal injection molding machine. The injection molding process is controlled as follows: barrel gradient temperature 185℃, 195℃, 205℃, nozzle 200℃, mold temperature controlled at 50℃ to optimize PP crystallization morphology, injection pressure 90MPa, holding pressure 60MPa, cooling and setting time 18s. The molded nozzle tube product is placed in a 85℃ devolatilization oven for continuous heat treatment for 2h to completely remove trace amounts of benzeneacetone and other odor molecules produced by DCP decomposition, to obtain a high-toughness polypropylene nozzle tube.

[0042] Example 3

[0043] A method for preparing a high-toughness polypropylene suction tube includes the following steps:

[0044] Step 1: Take 100 parts by weight of homopolymer polypropylene (melt index 3.5 g / 10 min), 3 parts of maleic anhydride, 1.5 parts of vinyltriethoxysilane (KH171), 0.12 parts of dicumyl peroxide (DCP), 0.4 parts of anti-degradation composite agent (hindered phenol 1010 and phosphite 168 compounded in a 2:1 ratio), and 0.1 parts of white oil. First, wet the homopolymer polypropylene particles with 0.1 parts of white oil at high speed. Then, add the premixed MAH, KH171, and DCP, and mix at 850 r / min for 6 min in a high-speed mixer to prepare a premix. Feed the premix into a twin-screw extruder, setting the feeding section temperature to 150°C, the compression section temperature to 175°C, the melting section temperature to 190°C, the reaction section temperature to 200°C, and the die head temperature to 190°C, with a screw speed of 220 r / min. Turn on vacuum at the end of the extruder to obtain co-grafted polypropylene particles.

[0045] Step 2: Take 8 parts by weight of polyolefin elastomer (POE), 4 parts of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.2 parts of divinylbenzene (DVB), and 0.05 parts of dicumyl peroxide (DCP). First, put POE and SEBS into a mixer and melt and homogenize them at 160°C for 2 minutes. Then, add the premixed solution of DVB and DCP, increase the speed to 65 r / min, and continue mixing for 8 minutes to obtain a pre-crosslinked composite elastomer.

[0046] Step 3: Take 5 parts by weight of sodium montmorillonite and 2 parts by weight of hexadecyltrimethylammonium bromide (CTAB). Dissolve CTAB completely in a mixed solvent of deionized water and ethanol (volume ratio 4:1) to prepare a 5% suspension. Then add montmorillonite and stir at 750 r / min for 4 h at 83 °C in a constant temperature stirred tank. After the reaction is complete, filter the mixture. Wash the filter cake twice with hot ethanol at 70 °C to completely remove free quaternary ammonium salts, and then wash it repeatedly with deionized water until the filtrate shows no bromide ion reaction (no turbidity) when tested with 0.1 mol / L silver nitrate. Finally, dry the washed montmorillonite in a vacuum drying oven at 105 °C to constant weight and then pulverize it into an organo-modified montmorillonite.

[0047] Step 4: Take 100 parts by weight of the co-grafted PP particles prepared in Step 1, 13 parts of the pre-crosslinked composite elastomer prepared in Step 2, 4 parts of the organomodified montmorillonite prepared in Step 3, 3 parts of maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), 0.6 parts of polyoxypropylene diamine (D-2000), and 0.3 parts of epoxy-functionalized silsesquioxane (Epoxy-POSS). To promote the hydrolysis of siloxane, 0.02 parts of deionized water were pre-sprayed onto the surface of the organomodified montmorillonite before feeding. All components were fed into a twin-screw extruder, with the following temperatures set: feeding section 160℃, compression section 185℃, dispersion section 200℃, homogenization section 190℃, screw speed 200 r / min, and high vacuum exhaust (-0.09 MPa) to obtain modified polypropylene particles.

[0048] Step 5: The modified polypropylene particles were dried in hot air circulation at 90℃ for 5 hours, and then fed into a horizontal injection molding machine. The injection molding process was controlled as follows: barrel temperature gradient 185℃, 195℃, 205℃, nozzle 200℃, mold temperature controlled at 50℃ to optimize PP crystal morphology, injection pressure 90MPa, holding pressure 60MPa, and cooling and setting time 18s. The molded nozzle tube was then placed in an 85℃ devolatilization oven for continuous heat treatment for 2 hours to completely remove trace amounts of acetophenone and other odor molecules produced by DCP decomposition, resulting in a high-toughness polypropylene nozzle tube.

[0049] Example 4

[0050] A method for preparing a high-toughness polypropylene suction tube includes the following steps:

[0051] Step 1: Take 100 parts by weight of homopolymer polypropylene (melt index 3.5 g / 10 min), 4 parts of maleic anhydride, 1.5 parts of vinyltriethoxysilane (KH171), 0.12 parts of dicumyl peroxide (DCP), 0.4 parts of anti-degradation composite agent (hindered phenol 1010 and phosphite 168 compounded in a 2:1 ratio), and 0.1 parts of white oil. First, wet the homopolymer polypropylene particles with 0.1 parts of white oil at high speed. Then, add the premixed MAH, KH171, and DCP, and mix at 850 r / min for 6 min in a high-speed mixer to prepare a premix. Feed the premix into a twin-screw extruder, setting the feeding section temperature to 150°C, the compression section temperature to 175°C, the melting section temperature to 190°C, the reaction section temperature to 200°C, and the die head temperature to 190°C, with a screw speed of 220 r / min. Turn on vacuum at the end of the extruder to obtain co-grafted polypropylene particles.

[0052] Step 2: Take 8 parts by weight of polyolefin elastomer (POE), 5 parts of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.2 parts of divinylbenzene (DVB), and 0.05 parts of dicumyl peroxide (DCP). First, put POE and SEBS into a mixer and melt and homogenize them at 160°C for 2 minutes. Then, add the premixed solution of DVB and DCP, increase the speed to 65 r / min, and continue mixing for 8 minutes to obtain a pre-crosslinked composite elastomer.

[0053] Step 3: Take 5 parts by weight of sodium montmorillonite and 3 parts by weight of hexadecyltrimethylammonium bromide (CTAB). Dissolve CTAB completely in a mixed solvent of deionized water and ethanol (volume ratio 4:1) to prepare a 5% suspension. Then add montmorillonite and stir at 750 r / min for 5 h in a constant temperature stirred tank at 85 °C. After the reaction is complete, filter the mixture. Wash the filter cake twice with hot ethanol at 70 °C to completely remove free quaternary ammonium salts, and then wash it repeatedly with deionized water until the filtrate shows no bromide ion reaction (no turbidity) when tested with 0.1 mol / L silver nitrate. Finally, dry the washed montmorillonite in a vacuum drying oven at 105 °C to constant weight and then pulverize it into an organo-modified montmorillonite.

[0054] Step 4: Take 100 parts by weight of the co-grafted PP particles prepared in Step 1, 15 parts of the pre-crosslinked composite elastomer prepared in Step 2, 5 parts of the organomodified montmorillonite prepared in Step 3, 3 parts of maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), 0.6 parts of polyoxypropylene diamine (D-2000), and 0.4 parts of epoxy-functionalized silsesquioxane (Epoxy-POSS). To promote the hydrolysis of siloxane, 0.02 parts of deionized water were pre-sprayed onto the surface of the organomodified montmorillonite before feeding. All components were fed into a twin-screw extruder, with the following temperatures set: feeding section 160℃, compression section 185℃, dispersion section 200℃, homogenization section 190℃, screw speed 200 r / min, and high vacuum exhaust (-0.09 MPa) to obtain modified polypropylene particles.

[0055] Step 5: The modified polypropylene particles were dried in hot air circulation at 90℃ for 5 hours, and then fed into a horizontal injection molding machine. The injection molding process was controlled as follows: barrel temperature gradient 185℃, 195℃, 205℃, nozzle 200℃, mold temperature controlled at 50℃ to optimize PP crystal morphology, injection pressure 90MPa, holding pressure 60MPa, and cooling and setting time 18s. The molded nozzle tube was then placed in an 85℃ devolatilization oven for continuous heat treatment for 2 hours to completely remove trace amounts of acetophenone and other odor molecules produced by DCP decomposition, resulting in a high-toughness polypropylene nozzle tube.

[0056] Example 5

[0057] A method for preparing a high-toughness polypropylene suction tube includes the following steps:

[0058] Step 1: Take 100 parts by weight of homopolymer polypropylene (melt index 3.5 g / 10 min), 2 parts of maleic anhydride, 1.5 parts of vinyltriethoxysilane (KH171), 0.12 parts of dicumyl peroxide (DCP), 0.4 parts of anti-degradation composite agent (hindered phenol 1010 and phosphite 168 compounded in a 2:1 ratio), and 0.1 parts of white oil. First, wet the homopolymer polypropylene particles with 0.1 parts of white oil at high speed. Then, add the premixed MAH, KH171, and DCP, and mix at 850 r / min for 6 min in a high-speed mixer to prepare a premix. Feed the premix into a twin-screw extruder, setting the feeding section temperature to 150°C, the compression section temperature to 175°C, the melting section temperature to 190°C, the reaction section temperature to 200°C, and the die head temperature to 190°C, with a screw speed of 220 r / min. Turn on vacuum at the end of the extruder to obtain co-grafted polypropylene particles.

[0059] Step 2: Take 8 parts by weight of polyolefin elastomer (POE), 3 parts of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.2 parts of divinylbenzene (DVB), and 0.05 parts of dicumyl peroxide (DCP). First, put POE and SEBS into a mixer and melt and homogenize them at 160°C for 2 minutes. Then, add the premixed solution of DVB and DCP, increase the speed to 65 r / min, and continue mixing for 8 minutes to obtain a pre-crosslinked composite elastomer.

[0060] Step 3: Take 5 parts by weight of sodium montmorillonite and 1 part by weight of hexadecyltrimethylammonium bromide (CTAB). Dissolve CTAB completely in a mixed solvent of deionized water and ethanol (volume ratio 4:1) to prepare a 5% suspension. Then add montmorillonite and stir at 750 r / min for 3 h at 80 °C in a constant temperature stirred tank. After the reaction is complete, filter the mixture. Wash the filter cake twice with hot ethanol at 70 °C to completely remove the free quaternary ammonium salt, and then wash it repeatedly with deionized water until the filtrate shows no bromide ion reaction (no turbidity) when tested with 0.1 mol / L silver nitrate. Finally, dry the washed montmorillonite in a vacuum drying oven at 105 °C to constant weight and then pulverize it into an organo-modified montmorillonite.

[0061] Step 4: Take 100 parts by weight of the co-grafted PP particles prepared in Step 1, 10 parts of the pre-crosslinked composite elastomer prepared in Step 2, 3 parts of the organomodified montmorillonite prepared in Step 3, 3 parts of maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), 0.6 parts of polyoxypropylene diamine (D-2000), and 0.2 parts of epoxy-functionalized silsesquioxane (Epoxy-POSS). To promote the hydrolysis of siloxane, 0.02 parts of deionized water are pre-sprayed onto the surface of the organomodified montmorillonite before feeding. Feed all components into a twin-screw extruder, with the following temperatures set: feeding section 160℃, compression section 185℃, dispersion section 200℃, homogenization section 190℃, screw speed 200 r / min, and high vacuum exhaust (-0.09 MPa) to obtain modified polypropylene particles.

[0062] Step 5: The modified polypropylene particles were dried in hot air circulation at 90℃ for 5 hours, and then fed into a horizontal injection molding machine. The injection molding process was controlled as follows: barrel temperature gradient 185℃, 195℃, 205℃, nozzle 200℃, mold temperature controlled at 50℃ to optimize PP crystal morphology, injection pressure 90MPa, holding pressure 60MPa, and cooling and setting time 18s. The molded nozzle tube was then placed in an 85℃ devolatilization oven for continuous heat treatment for 2 hours to completely remove trace amounts of acetophenone and other odor molecules produced by DCP decomposition, resulting in a high-toughness polypropylene nozzle tube.

[0063] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that homopolymer polypropylene particles are directly used without any modification treatment, and the nozzle is directly prepared according to the injection molding process in step 5 of Example 1.

[0064] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 1 is omitted, and the co-grafted polypropylene particles in step 4 are replaced with ordinary polypropylene particles.

[0065] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that steps 2 and 3 are omitted, the pre-crosslinked composite elastomer in step 4 is replaced with a polyolefin elastomer, and the organic montmorillonite is replaced with montmorillonite.

[0066] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that in step S4, polyoxypropylene diamine (D-2000) and epoxy-functionalized silsesquioxane (Epoxy-POSS) are not added.

[0067] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that polyoxypropylene diamine (D-2000) is not added in step S4.

[0068] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that in step S4, epoxy-functionalized silsesquioxane (Epoxy-POSS) is not added.

[0069] Performance testing:

[0070] 1. Low-Temperature Notched Impact Strength Test of Simply Supported Beams: According to GB / T 1043.1-2008 standard, modified polypropylene particles prepared in the examples and comparative examples were injection molded into standard specimens (80mm×10mm×4mm), with a 2mm deep Type A notch cut in the center of each specimen. The specimens were placed in a low-temperature test chamber and kept at -20℃ for 4 hours before being immediately tested using a pendulum impact testing machine. This indicator reflects the toughness level of the material under extremely low-temperature conditions and is a core indicator for evaluating the resistance to brittle fracture during winter transportation of the nozzle. The test results are shown in Table 1.

[0071] 2. Elongation at break test: According to GB / T 1040.2-2006 standard, modified polypropylene particles prepared in the examples and comparative examples were injection molded into standard specimens (type 1A, dimensions: total length 150mm, gauge length 50mm, end width 20mm, thickness 2mm). Tensile tests were performed using an electronic universal testing machine with a tensile rate set to 50mm / min. Five parallel specimens were tested in each group, and the average value was taken as the final result. This index characterizes the plastic deformation capacity of the nozzle tube under tension or bending, and is directly related to the fracture toughness during use. The test results are shown in Table 1.

[0072] 3. Flexural Modulus Test: According to GB / T 9341-2008 standard, modified polypropylene particles prepared in the examples and comparative examples were injection molded into standard specimens (size: 80mm × 10mm × 4mm). A three-point bending test was performed using an electronic universal testing machine, with a span set to 64mm and a bending rate set to 2mm / min. Five parallel specimens were tested in each group, and the average value was taken as the final result. This index reflects the structural rigidity of the nozzle tube, ensuring that the nozzle tube does not undergo excessive deformation during assembly and sucking. The test results are shown in Table 1.

[0073] 4. Stress Whitening Resistance Test: A visual rating method was used. Flat sections of the nozzle tubes from each embodiment and comparative example were selected. A Shore D hardness tester with a matching indenter was used. At room temperature, a pressure of 50 N was applied for 10 seconds, and the indenter was removed. The appearance of white marks was observed at the pressed area. Simultaneously, the microstructure of the marked area was observed using an optical microscope (50x magnification). The samples were then placed in a -20℃ low-temperature environment for 2 hours, and the above operation was repeated. Based on the presence and severity of whitening marks, five levels were assigned (Level 1: No whitening marks; Level 2: Slight whitening, barely perceptible to the naked eye; Level 3: Obvious whitening, clearly visible to the naked eye; Level 4: Severe whitening, accompanied by slight cracks; Level 5: Obvious fracture in the whitening area). Five samples were tested in each group, and the highest level was taken as the stress whitening resistance level for that sample. This index reflects the interfacial bonding stability of the nozzle tube under stress, avoiding brittle defects caused by stress concentration. The test results are shown in Table 1.

[0074] Table 1:

[0075] Test specimen Impact strength at -20°C (kJ / m2) Elongation at break (%) Flexural modulus (MPa) Stress whitening resistance rating (room temperature / -20°C) Example 1 12.8 486 1525 1st / 2nd Example 2 11.2 461 1504 1st / 2nd Example 3 12.1 472 1531 1st / 1st Example 4 13.5 494 1553 1st / 2nd Example 5 10.5 456 1487 1st / 3rd Comparative Example 1 2.3 27 1450 3rd / 5th Comparative Example 2 4.5 115 1123 3rd / 4th Comparative Example 3 5.8 232 1281 3rd / 4th Comparative Example 4 7.2 311 1496 2nd / 4th Comparative Example 5 8.1 336 1538 2nd / 4th Comparative Example 5 9.2 422 1465 2nd / 3rd Comparative Example 5 2nd / 3rd

[0076] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of making a high toughness polypropylene spout tube, characterized by, The method comprises the following steps: S1, mixing homopolymer polypropylene, maleic anhydride, vinyl triethoxysilane, dicumyl peroxide and anti-degradation complexing agent, adding white oil wetting, high-speed mixing to obtain a premix, and putting the premix into a twin-screw extruder for melt reaction extrusion to obtain a co-grafted polypropylene particle; S2, melting and homogenizing a polyolefin elastomer and a styrene-ethylene-butylene-styrene block copolymer, adding a premix of divinylbenzene and dicumyl peroxide, and performing internal mixing to obtain a pre-crosslinked complex elastomer; S3, dissolving cetyltrimethylammonium bromide in a mixed solvent of deionized water and ethanol, adding sodium-based montmorillonite for constant temperature stirring reaction, and after the reaction is completed, performing suction filtration, washing, drying and crushing to obtain an organic montmorillonite; S4, mixing the co-grafted polypropylene particle, the pre-crosslinked complex elastomer, the organic montmorillonite, the maleic anhydride grafted polyolefin elastomer, the polypropylene oxide diamine and the epoxy-functionalized silsesquioxane, wherein deionized water is pre-sprayed and adsorbed on the surface of the organic montmorillonite; putting all components into a twin-screw extruder for melt blending extrusion to obtain a modified polypropylene particle; S5, drying the modified polypropylene particle, putting it into an injection molding machine for injection molding to obtain a nozzle tube blank; and heat treating the nozzle tube blank to obtain the high-toughness polypropylene nozzle tube.

2. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S1, the mass ratio of the homopolymer polypropylene to the maleic anhydride is 100:(2-4).

3. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S1, the anti-degradation complexing agent is composed of hindered phenol 1010 and phosphite 168.

4. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S2, the mass ratio of the polyolefin elastomer to the styrene-ethylene-butylene-styrene block copolymer is 8:(3-5).

5. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S3, the mass ratio of the sodium-based montmorillonite to the cetyltrimethylammonium bromide is 5:(1-3).

6. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S3, the reaction temperature is 80-85°C, and the reaction time is 3-5h.

7. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S4, the mass ratio of the co-grafted polypropylene particle to the pre-crosslinked complex elastomer is 100:(10-15).

8. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S4, the mass ratio of the grafted polypropylene particle to the organic montmorillonite is 100:(3-5).

9. The method for preparing a high-toughness polypropylene suction tube according to claim 1, characterized in that, In the step S4, the mass ratio of the polypropylene oxide diamine to the epoxy-functionalized silsesquioxane is 6:(2-4).

10. A high toughness polypropylene mouthpiece tube characterized by, Prepared by the method of any one of claims 1-9.

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