WO2023116364A1 - Folding-resistant polypropylene composite material, and preparation method therefor and use thereof - Google Patents

Abstract

The present invention discloses a folding-resistant polypropylene composite material, and a preparation method therefor and the use thereof, which belong to the technical field of polymer materials. The folding-resistant polypropylene composite material comprises the following components in parts by weight: 40-60 parts of metallocene polypropylene, 10-30 parts of an impact-resistant co-polypropylene, 20-30 parts of a filler, 5-10 parts of a thermoplastic elastomer, and 0-3 parts of an auxiliary agent, wherein the metallocene polypropylene has a molecular weight distribution index Mw/Mn of 2.3-2.7 and a degree of crystallinity of 32-38%, and the test standard for the degree of crystallinity is ISO 11357-2016; and the impact-resistant co-polypropylene has a molecular weight distribution index Mw/Mn of 3.9-4.4 and a degree of crystallinity of 31-37%, and the mass content of ethylene propylene rubber in the impact-resistant co-polypropylene is 15-30%. The folding-resistant polypropylene composite material of the present invention can improve the elongation at break of a hinge structure workpiece, is free from any fractures, even if the surface layer thereof is folded repeatedly, and has a good appearance.

Description

A kind of anti-folding polypropylene composite material and its preparation method and application technical field

The invention relates to the technical field of polymer materials, and more specifically relates to a folding-resistant polypropylene composite material, a preparation method thereof, and its application in the preparation of plastic hinges and plastic hinges.

Background technique

Polypropylene (PP) material has very good resistance to stress cracking and high bending fatigue life, which is why polypropylene material is commonly known as "100-fold glue". Polypropylene material can be used to prepare fast food boxes, washing product covers, storage box covers, suitcases and auto parts and other hinged structural parts that connect two substrates. Such hinged structural parts can be folded at an angle of nearly 180°. Can reach 7 million times.

The polypropylene materials used to prepare hinge structural parts mostly use homopolypropylene, copolymerized polypropylene and random polypropylene as the matrix, adding inorganic rigid particles and polyolefin thermoplastic elastomers, and can achieve rigidity and toughness after injection molding parts Balanced to achieve multiple folds without breaking.

The prior art discloses a folding-resistant polypropylene composite material, which is used to prepare automobile parts with hinged structures such as automobile fuse boxes. Metallocene elastomers are added to homopolymerized polypropylene and copolymerized polypropylene as reinforcements. The toughening agent improves the folding resistance of polypropylene at low temperature and mineral filling, and inorganic fillers are added to improve the rigidity. However, due to the rubber phase of the metallocene elastomer and the addition of the rigid particles of the inorganic filler, various heterogeneous components appear in the polypropylene material, and the stress defect points that appear during the repeated folding process of the hinge structure made of this material will gradually The increase will cause the surface layer of the part to crack after repeated folding. Moreover, its elongation at break is only 260-300%, which cannot meet the higher requirement of elongation at break.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defect and deficiency that the surface layer of the existing folding-resistant polypropylene composite material is prone to cracking and low elongation at break, and to provide a folding-resistant polypropylene composite material, which is made of metallocene polypropylene and anti-folding polypropylene. The synergistic effect of punching copolymerized polypropylene effectively improves the elongation at break of the folding-resistant polypropylene composite material. After being prepared into hinge structure parts, the surface layer will not crack after repeated folding.

Another object of the present invention is to provide a method for preparing a folding-resistant polypropylene composite material.

Another object of the present invention is to provide an application of a folding-resistant polypropylene composite material in the preparation of plastic hinges.

Another object of the present invention is to provide a plastic hinge.

The above object of the present invention is achieved through the following technical solutions:

A folding-resistant polypropylene composite material, in parts by weight, comprises the following components:

Wherein, the molecular weight distribution index M _w /M _n of the metallocene polypropylene is 2.3-2.7, the crystallinity is 32-38%, and the crystallinity test standard is ISO 11357-2016;

The molecular weight distribution index M _w /M _n of the impact copolymerized polypropylene is 3.9-4.4, the degree of crystallinity is 31-37%, the test standard for the degree of crystallinity is ISO 11357-2016, and the ethylene-propylene rubber in the impact-resistant copolymerized polypropylene is The mass content is 15-30%.

The molecular weight distribution index M _w /M _n is an index used to indicate the dispersion degree of the molecular weight distribution, M _w is the weight average molecular weight, and M _n is the number average molecular weight.

The test method for the mass content of ethylene-propylene rubber in impact copolymer polypropylene is: dissolve the sample in n-decane with a concentration of 98%, extract it in a flask with a reflux device at 145 ° C, cool to room temperature, The rubber phase is dissolved in n-decane, and the rest crystallizes out and is filtered. Then add acetone to the filtrate to precipitate the rubber phase in the filtrate, filter, dry, weigh, and calculate the rubber phase content.

What needs to be explained is:

The anti-folding polypropylene composite material of the present invention can realize the improvement of the elongation at break through the optimization and synergy of the resin base material, and does not affect other physical and mechanical properties, and the repeated folding of the surface layer during the continuous use of the hinge structure will not Cracks will occur, and the hinged structural parts will have a good appearance. And on the basis of maintaining the balance of rigidity and toughness, the composite material can also improve the rigidity to a certain extent.

The action mechanism of each component of the folding-resistant polypropylene composite material of the present invention is specifically as follows:

The molecular weight distribution index M _w /M _n of metallocene polypropylene is 2.3-2.7, and the crystallinity is 32-38%. It has the characteristics of narrow molecular weight distribution, high degree of entanglement among molecular chains, and low crystallinity; The propylene molecular weight distribution index M _w /M _n is 3.9-4.4, the crystallinity is 31-37%, the mass content of ethylene-propylene rubber in the impact copolymer polypropylene is 15-30%, and the molecular weight distribution is wide and the crystallinity is low. , The characteristics of high rubber content.

The invention uses metallocene polypropylene as the main matrix, and fully utilizes the characteristics of narrow molecular weight distribution and high degree of intertwining of molecular chains of the metallocene polypropylene material. In injection molding, when metallocene polypropylene forms a hinge structure with a small thickness, due to the high degree of entanglement between the molecular chains and the weak degree of orientation, the molecular chains of metallocene polypropylene are less likely to be stretched obviously, so in The original structural shape can be maintained when it is folded repeatedly in the later stage, and no surface damage occurs.

At the same time, the invention utilizes the impact copolymer polypropylene with a wide molecular weight distribution to reduce the lubrication and steric resistance in the melt flow, and the material melt can be successfully injection molded into a hinge structure with a thickness that changes from wide to narrow, which improves the reliability of the composite material. Injection moldability.

The metallocene polypropylene of the present invention and the impact copolymer polypropylene are used as the matrix together, and the crystallinity of both is low. When the hinge is repeatedly folded, the degree of damage and translation of the crystallization area is naturally low, and the degree of molecular chain entanglement is high, so it can Improve the elongation at break, so as to achieve the effect that the surface layer is folded without breaking.

For the polypropylene composite material of the injection molded hinge structure, the state of the ethylene-propylene rubber in the surface layer has an effect on the elongation at break at the same time. When the surface layer appears stretched and bent, the ethylene-propylene rubber phase of the impact copolymer polypropylene The tensile and bending states appear simultaneously, while the ethylene-propylene rubber phase can withstand large tensile and bending deformations, and the macroscopically shows that the elongation at break of the composite material is better.

The thermoplastic elastomer has a low crystallinity, which not only acts as a rubber phase, but also reduces the overall crystallinity of the material to a certain extent, which is beneficial to the improvement of the tensile elongation at break.

When the mass content of ethylene-propylene rubber in impact copolymerized polypropylene is less than 15%, the elongation at break cannot be improved.

When the mass content of ethylene-propylene rubber in the impact copolymer polypropylene is higher than 30%, although it is beneficial to the improvement of the elongation at break, it will affect the balance of the overall rigidity and toughness of the composite material.

The function of the filler is to improve the rigidity of the material, and the function of the thermoplastic elastomer is to improve the toughness of the material, and the balance between the rigidity and toughness can be achieved by controlling the filler and the thermoplastic elastomer within the scope of the present invention.

Preferably,

In parts by weight, it includes the following components:

The auxiliary agent is one or more of antioxidant, lubricant or toner.

The proportion of metallocene polypropylene and impact copolymer polypropylene should be maintained at an appropriate ratio. Too high or too low will not be effective. When the metallocene polypropylene is 45-50 parts, the impact copolymer polypropylene is 25-28 parts. When the ratio of the two is kept at 1: (0.4-0.6), it can effectively prevent the surface layer from cracking after folding and increase the elongation at break.

The role of thermoplastic elastomer is to improve the toughness of the material. If it is less than 6 parts, the toughness of thermoplastic elastomer is poor; adding more than 7 parts will improve the toughness of the material, but it will make the material too soft, resulting in a decrease in rigidity.

The content of the filler is related to the rigidity of the final material. If the amount added is less than 25 parts, the filler will not significantly improve the rigidity of the material; when the added amount exceeds 28 parts, the rigidity will be significantly improved, but it will easily break.

Preferably, the crystallinity of the metallocene polypropylene is 34-36%.

The lower the crystallinity of metallocene polypropylene, the higher the content of polypropylene molecular chains in the amorphous state. When repeated folding, the degree of destruction and translation of the crystallization area is naturally low, and the degree of molecular chain entanglement is high, so it can improve the fracture rate. Elongation. The crystallinity of metallocene polypropylene is less than 34%, but this can negatively affect the rigidity of the material.

Preferably, the crystallinity of the impact copolymer polypropylene is 32-35%, and the mass content of ethylene-propylene rubber in the impact copolymer polypropylene is 25-30%.

The crystallinity of impact copolymerized polypropylene is low, and the content of polypropylene molecular chain in the amorphous state is increased. During repeated folding, the degree of entanglement with the molecular chain of metallocene polypropylene is high, so the elongation at break can be improved. The crystallinity of metallocene polypropylene is lower than 32%, but this can negatively affect the rigidity of the material.

The mass content of ethylene-propylene rubber in the impact copolymer polypropylene is relatively high, and the content of the rubber phase on the surface of the hinge is relatively high, which further increases the amount of tensile and bending deformation, which is conducive to improving the elongation at break of the composite material. Higher than 30% ethylene propylene rubber in impact copolymer polypropylene can negatively affect the rigidity of the material.

Preferably, the mass melt mass flow rate of the metallocene polypropylene is 20-30 g/10 min, the test standard is ISO1133-2011, and the test condition is 230° C., 2.16 kg.

The high melt mass flow rate of metallocene polypropylene is conducive to passing through the hinge structure with narrowed thickness, preventing obvious molecular chain stretching when passing through the hinge structure.

When the melt mass flow rate is lower than 20g/10min, it is not conducive for the composite material to pass through the cavity with a thickness of only 0.2-0.5mm, and there will be a more significant phenomenon of molecular chain stretching and orientation, showing that the hinge structure is doing repeated folding When there is obvious crease whitening, surface cracks and other phenomena.

When the melt mass flow rate is higher than 30g/10min, due to the narrow molecular weight distribution of metallocene polypropylene itself, the main factors affecting the melt mass flow rate are the molecular weight and molecular weight distribution of the polymer. When the melt mass flow rate is high, The molecular weight of polypropylene decreases naturally. Although the smooth passage of the modified composite material through the hinge structure is obviously improved, the molecular weight of the main components is also significantly reduced, showing that the impact performance of the modified composite material is significantly reduced. .

More preferably, the flexural modulus of the metallocene polypropylene is 1200-1600 MPa, and the test standard is ISO178-2010; the notched Izod impact strength of the metallocene polypropylene is 2-10 kJ/m ² , and the test standard is ISO180 -2000, the test temperature is 23°C.

The flexural modulus of metallocene polypropylene is 1200-1600MPa, and the notched Izod impact strength is 2-10kJ/m ² , which can achieve a balance of rigidity and toughness, so that the final material can also achieve a balance of rigidity and toughness.

Preferably, the notched Izod impact strength of the impact copolymer polypropylene is 30-50 kJ/m ² , the test standard is ISO180-2000, and the test temperature is 23°C.

The rubber content of impact copolymer polypropylene is relatively high, and the notched impact strength of Izod beam is 30-50kJ/m ² , which has high impact resistance.

More preferably, the melt mass flow rate of the impact copolymer polypropylene is 10-30g/10min, the test standard is ISO1133-2011; the flexural modulus of the impact copolymer polypropylene is 800-1600MPa, the test standard is It is ISO178-2010.

The flexural modulus of impact copolymer polypropylene is 800-1600MPa, and the notched Izod impact strength is 30-50kJ/m ² , which can achieve a balance of rigidity and toughness. When used in conjunction with metallocene polypropylene, the final material can also achieve rigidity and resilience balance.

Preferably, the thermoplastic elastomer is an ethylene-octene copolymer, the crystallinity of the thermoplastic elastomer is 3-6%, and the crystallinity test standard is ISO 11357-2016.

For crystalline ethylene-octene copolymers, the crystallinity is generally between 8 and 10% by DSC method, while the crystallinity of non-crystalline ethylene-octene copolymers is generally tested by DSC method. Between 3 and 6%, the present invention uses non-crystalline ethylene-octene copolymer as a toughening agent, its main purpose is to reduce the crystallinity in the modified composite system, and the ethylene-octene copolymer rubber phase is on the surface of the hinge structure In the stretched state, the microstructural state of the ethylene-octene copolymer itself is more effectively utilized, so that when the hinge structure is subjected to large deformations of stretching and bending, the ethylene-octene copolymer itself also has a good bearing capacity. The ability to deform meets the requirement that the surface of the hinge structure does not break.

The crystallinity of each component of the present invention adopts ISO 11357-2016 standard method to measure.

The DSC test method is specifically: test the DSC curve of the polymer, obtain the area surrounded by the melting curve and the baseline, convert it into heat, that is, the melting heat of the polymer crystallization part, the melting heat of the polymer crystallization part is more than the theoretical melting when 100% crystallization Enthalpy, which is the degree of crystallinity of the polymer.

Wherein, the filler can be talcum powder and/or calcium carbonate.

In practical applications, additives such as antioxidants, lubricants and toners can also be added according to actual performance needs.

Wherein, in parts by weight, 0-0.6 parts of antioxidant, 0-0.2 parts of lubricant and 0-1.5 parts of toner are also included.

The main antioxidant can be selected from one or a mixture of hindered phenolic antioxidants.

Auxiliary antioxidants can be selected from one or a mixture of phosphites.

The hindered phenolic antioxidant can be one or a mixture of antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 1024, antioxidant AO-330, etc.

The phosphite antioxidant can be one or a mixture of antioxidant 168, antioxidant 626, antioxidant 618, and antioxidant 398V.

The lubricant can be selected from one or a mixture of lubricants of silicones, esters, amides, polyethylenes, stearic acids, fatty acids and esters.

Toner can choose carbon black and other toners according to the actual color requirements.

The antioxidant can improve the anti-oxidation effect of the folding-resistant polypropylene composite material, the lubricant can improve the lubricating effect of the folding-resistant polypropylene composite material, and the toner can dye the folding-resistant polypropylene composite material.

The invention also protects the preparation method of the anti-folding polypropylene composite material, which specifically includes the following steps: uniformly mixing the components, melt extruding and granulating at 160-220°C through a twin-screw extruder, and obtaining the obtained product after drying The fold-resistant polypropylene composite is described.

The folding-resistant polypropylene composite material prepared by the invention has good elongation at break and mechanical properties, and can be widely used in the preparation of plastic products. The invention especially protects the advantages of the folding-resistant polypropylene composite material in the preparation of plastic hinges. application.

The invention also specifically protects a hinge, and the plastic hinge is prepared from the folding-resistant polypropylene composite material.

Preferably, the wall thickness of the plastic hinge is 0.2-0.5mm.

Wherein, the preparation method of the plastic hinge of the present invention can be injection molding.

Compared with prior art, the beneficial effect of the present invention is:

The anti-folding polypropylene composite material of the present invention can realize the improvement of the elongation at break through the optimization and synergy of the resin base material, and does not affect other physical and mechanical properties, and the repeated folding of the surface layer during the continuous use of the hinge structure will not Cracks will occur, and the hinged structural parts will have a good appearance.

The fracture elongation rate of the plastic hinge prepared by the folding-resistant polypropylene composite material of the invention can be as high as 525%, and the surface layer will not be damaged after repeated folding for 10^7 times.

Description of drawings

Figure 1 shows the appearance of the plastic hinge surface without cracking.

Figure 2 shows the cracked appearance of the plastic hinge surface.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the examples of the present invention are conventionally purchased raw material reagents.

Metallocene polypropylene 1 is mPP MH7700, molecular weight distribution index M _w /M _n is 2.4, crystallinity is 35%, melt mass flow rate is 25g/10min, flexural modulus is 1550MPa, Izod notched impact strength is 3.0kJ/ m ² , Korea LG Chem;

Metallocene polypropylene 2 is mPP MR10MX0, molecular weight distribution index _Mw / _Mn is 2.3, crystallinity is 32%, melt mass flow rate is 10g/10min, flexural modulus is 1300MPa, Izod notched impact strength is 5kJ/m ² , Korea Total Corporation;

Metallocene polypropylene 3 is mPP MH1700, molecular weight distribution index M _w /M _n is 2.7, crystallinity is 38%, melt mass flow rate is 40g/10min, flexural modulus is 1550MPa, Izod notched impact strength is 3.0kJ/ m ² , Korea LG Chem;

Metallocene polypropylene 4 is mPP JHM2002, molecular weight distribution index _Mw / _Mn is 2.4, crystallinity is 34%, melt mass flow rate is 20g/10min, flexural modulus is 1250MPa, Izod notched impact strength is 5kJ/m ² , Shandong Jincheng Petrochemical;

Metallocene polypropylene 5 is mPP HM562S, molecular weight distribution index M _w /M _n is 2.4, crystallinity is 36%, melt mass flow rate is 30g/10min, flexural modulus is 1300MPa, Izod notched impact strength is 4.0kJ/ m ² , LyondellBasell Industries;

Metallocene polypropylene 6 is mPP WMG03UX, molecular weight distribution index M _w /M _n is 3.0, crystallinity is 40%, melt mass flow rate is 30g/10min, flexural modulus is 1450MPa, Izod notched impact strength is 3.5kJ/ m ² , Japan JPP Company;

Metallocene polypropylene 7 is mPP MR30MX0, molecular weight distribution index _Mw / _Mn is 2.0, crystallinity is 35%, melt mass flow rate is 30g/10min, flexural modulus is 1250MPa, Izod notched impact strength is 5kJ/m ² , Korea Total Corporation;

Metallocene polypropylene 8 is mPP WFW4M, molecular weight distribution index _Mw / _Mn is 3.0, crystallinity is 35%, melt mass flow rate is 8g/10min, flexural modulus is 1050MPa, Izod notched impact strength is 6.0kJ/m ² , Japan JPP company;

Metallocene polypropylene 9 is mPP M3720WZ, the molecular weight distribution index M _w /M _n is 2.4, the crystallinity is 28%, the melt mass flow rate is 24g/10min, the flexural modulus is 1450MPa, and the notched Izod impact strength is 3.0kJ/ m ² , Korea Total Corporation;

Metallocene polypropylene 10 is mPP MH1850, molecular weight distribution index M _w /M _n is 2.4, crystallinity is 40%, melt mass flow rate is 60g/10min, flexural modulus is 2000MPa, Izod notched impact strength is 3.0kJ/ m ² , Korea LG Chem;

The impact copolymer polypropylene 1 is PP SP179, the molecular weight distribution index M _w /M _n is 4.0, the crystallinity is 35%, the mass content of ethylene-propylene rubber is 27%, the notched Izod impact strength is 45kJ/m ² , and the melt mass The flow rate is 10g/10min, the flexural modulus is 850MPa, Sinopec Qilu Branch;

The impact copolymer polypropylene 2 is PP 1120D, the molecular weight distribution index _Mw / _Mn is 3.9, the crystallinity is 31%, the mass content of ethylene-propylene rubber is 15%, the notched Izod impact strength is 28kJ/ ^m2 , and the melt mass The flow rate is 15g/10min, the flexural modulus is 1475MPa, Taiwan Plastic Industry Co., Ltd.;

The impact copolymer polypropylene 3 is PP 1692, the molecular weight distribution index M _w /M _n is 4.4, the crystallinity is 37%, the mass content of ethylene-propylene rubber is 30%, the notched Izod impact strength is 53kJ/m ² , and the melt quality The flow rate is 20g/10min, the flexural modulus is 1000MPa, LyondellBasell Industries;

The impact copolymer polypropylene 4 is PP K9017, the molecular weight distribution index M _w /M _n is 4.0, the crystallinity is 33.7%, the mass content of ethylene-propylene rubber is 29%, the notched Izod impact strength is 50kJ/m ² , and the melt mass The flow rate is 16g/10min, the flexural modulus is 900MPa, Taiwan Plastic Industry Co., Ltd.;

The impact copolymer polypropylene 5 is PP K9829H, the molecular weight distribution index M _w /M _n is 4.3, the crystallinity is 35.3%, the mass content of ethylene-propylene rubber is 25%, the notched Izod impact strength is 35kJ/m ² , and the melt mass The flow rate is 28g/10min, the flexural modulus is 1030MPa, Sinopec Yanshan Branch;

The impact copolymer polypropylene 6 is PP 2-9301, the molecular weight distribution index M _w /M _n is 3.5, the crystallinity is 40%, the mass content of ethylene-propylene rubber is 40%, the notched Izod impact strength is 60kJ/m ² , the melt The body mass flow rate is 30g/10min, the flexural modulus is 1100MPa, Inno-Comp Kft company;

The impact copolymer polypropylene 7 is PP 511MK40T, the molecular weight distribution index M _w /M _n is 4.0, the crystallinity is 35.8%, the mass content of ethylene-propylene rubber is 10%, the notched Izod impact strength is 10kJ/m ² , and the melt mass The flow rate is 30g/10min, the flexural modulus is 1250MPa, SABIC;

The impact copolymer polypropylene 8 is PP 6630A, the molecular weight distribution index M _w /M _n is 4.0, the crystallinity is 32.4%, the mass content of ethylene-propylene rubber is 35%, the notched Izod impact strength is 55kJ/m ² , and the melt mass The flow rate is 30g/10min, the flexural modulus is 1250MPa, Taiwan Plastic Industry Co., Ltd.;

The impact copolymer polypropylene 9 is PP 3208, the molecular weight distribution index M _w /M _n is 4.0, the crystallinity is 28.7%, the mass content of ethylene-propylene rubber is 22%, the notched Izod impact strength is 32kJ/m ² , and the melt mass The flow rate is 10g/10min, the flexural modulus is 1070MPa, Pinnacle Polymer Co., Ltd.;

The impact copolymer polypropylene 10 is PP 6510E, the molecular weight distribution index M _w /M _n is 4.1, the crystallinity is 38.5%, the mass content of ethylene-propylene rubber is 17%, the notched Izod impact strength is 21kJ/m ² , and the melt mass The flow rate is 10g/10min, the flexural modulus is 1500MPa, Taiwan Plastic Industry Co., Ltd.;

The impact copolymer polypropylene 11 is PP CMR648, the molecular weight distribution index M _w /M _n is 3.7, the crystallinity is 36.4%, the mass content of ethylene-propylene rubber is 28.5%, the notched Izod impact strength is 50kJ/m ² , and the melt mass The flow rate is 10g/10min, the flexural modulus is 1050MPa, Sasol Polymer Co., Ltd.;

The impact copolymer polypropylene 12 is PP BNU013, the molecular weight distribution index M _w /M _n is 4.6, the crystallinity is 35.7%, the mass content of ethylene-propylene rubber is 17%, the notched Izod impact strength is 25kJ/m ² , and the melt mass The flow rate is 22g/10min, the flexural modulus is 1030MPa, ExxonMobil Chemical Co., Ltd.;

Thermoplastic elastomer 1 is ethylene-octene copolymer POE LC565, crystallinity is 4.3%, LG Chemical Enterprise Co., Ltd.;

Thermoplastic elastomer 2 is ethylene-octene copolymer POE LC150, crystallinity is 3%, LG Chemical Enterprise Co., Ltd.;

Thermoplastic Elastomer 3 is ethylene-octene copolymer POE 8150 with a crystallinity of 6%, Dow Chemical Company;

Thermoplastic Elastomer 4 is ethylene-octene copolymer POE 8180 with 2% crystallinity, Dow Chemical Company;

Thermoplastic Elastomer 5 is ethylene-octene copolymer POE XLT 8677 with 10% crystallinity, The Dow Chemical Company;

Filler, talcum powder, is commercially available and what embodiment and comparative example use is the same;

Antioxidant, hindered phenolic antioxidant and phosphite antioxidant, the mass ratio of hindered phenolic antioxidant and phosphite antioxidant is 1:1, commercially available and embodiment and comparative example use are of the same kind;

Lubricant, amide lubricant, commercially available and what embodiment and comparative example use is the same;

Toner, carbon black masterbatch, commercially available and what embodiment and comparative example used are the same.

Examples 1-18

A folding-resistant polypropylene composite material, in parts by weight, comprises the following components:

Metallocene polypropylene; impact copolymer polypropylene; fillers and thermoplastic elastomers;

Wherein the specific content of each component is shown in Table 1 below.

Table 1 The composition of the anti-folding polypropylene composite material of each embodiment (in parts by weight)

components	1	2	3	4	5	6
Metallocene Polypropylene 1	48	40	60	45	50	48
Impact copolymer polypropylene 1	26	30	10	28	25	26
filler	26	30	20	28	25	26
Thermoplastic Elastomer 1	6.5	5	10	7	6	6.5
antioxidant	0.6	0.6	0.3	0.6	0.6	the
lubricant	0.2	0.2	0.2	0.2	0.2	the

Continued Table 1

components	7	8	9	10	11	12	13	14	15	16	17	18
Metallocene Polypropylene 1	the	the	the	the	48	48	48	48	48	48	48	48
Metallocene Polypropylene 2	48	the	the	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 3	the	48	the	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 4	the	the	48	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 5	the	the	the	48	the	the	the	the	the	the	the	the
Impact copolymer polypropylene 1	26	26	26	26	the	the	the	the	26	26	26	26
Impact copolymer polypropylene 2	the	the	the	the	26	the	the	the	the	the	the	the
Impact copolymer polypropylene 3	the	the	the	the	the	26	the	the	the	the	the	the
Impact copolymer polypropylene 4	the	the	the	the	the	the	26	the	the	the	the	the
Impact copolymer polypropylene 5	the	the	the	the	the	the	the	26	the	the	the	the
filler	26	26	26	26	26	26	26	26	26	26	26	26
Thermoplastic Elastomer 1	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5	the	the	the	the
Thermoplastic Elastomer 2	the	the	the	the	the	the	the	the	6.5	the	the	the
Thermoplastic Elastomer 3	the	the	the	the	the	the	the	the	the	6.5	the	the
Thermoplastic Elastomer 4	the	the	the	the	the	the	the	the	the	the	6.5	the

Thermoplastic Elastomer 5	the	the	the	the	the	the	the	the	the	the	the	6.5
antioxidant	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6
lubricant	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2

The preparation method of the above-mentioned folding-resistant polypropylene composite material comprises the following steps:

Mix the components uniformly, melt extrude and pelletize at 160-220°C through a twin-screw extruder, and obtain the folding-resistant polypropylene composite material after drying;

Among them, the length-to-diameter ratio of the twin-screw extruder is (36-48):1, the processing temperature is 160-220°C, the screw speed is 400-650rpm, and the feed rate is 300-1000kg/h.

Comparative example 1-18

A folding-resistant polypropylene composite material, in parts by weight, comprises the following components:

Metallocene polypropylene; impact copolymer polypropylene; filler and thermoplastic elastomer, wherein the specific content of each component is shown in Table 2 below.

Table 2 The composition of the anti-folding polypropylene composite material of each comparative example (in parts by weight)

components	1	2	3	4	5	6
Metallocene Polypropylene 1	48	48	48	the	30	70
Impact copolymer polypropylene 1	the	5	40	26	26	26
filler	26	26	26	26	26	26
Thermoplastic Elastomer 1	6.5	6.5	6.5	6.5	6.5	6.5
antioxidant	0.6	0.6	0.6	0.6	0.6	0.6
lubricant	0.2	0.2	0.2	0.2	0.2	0.2

Continued Table 2

components	7	8	9	10	11	12	13	14	15	16	17	18
Metallocene Polypropylene 1	the	the	the	the	the	48	48	48	48	48	48	48
Metallocene Polypropylene 6	48	the	the	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 7	the	48	the	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 8	the	the	48	the	the	the	the	the	the	the	the	the
Metallocene Polypropylene 9	the	the	the	48	the	the	the	the	the	the	the	the
Metallocene Polypropylene 10	the	the	the	the	48	the	the	the	the	the	the	the

Impact copolymer polypropylene 1	26	26	26	26	26	the	the	the	the	the	the	the
Impact copolymer polypropylene 6	the	the	the	the	the	26	the	the	the	the	the	the
Impact copolymer polypropylene 7	the	the	the	the	the	the	26	the	the	the	the	the
Impact copolymer polypropylene 8	the	the	the	the	the	the	the	26	the	the	the	the
Impact copolymer polypropylene 9	the	the	the	the	the	the	the	the	26	the	the	the
Impact copolymer polypropylene 10	the	the	the	the	the	the	the	the	the	26	the	the
Impact copolymer polypropylene 11	the	the	the	the	the	the	the	the	the	the	26	the
Impact copolymer polypropylene 12	the	the	the	the	the	the	the	the	the	the	the	26
filler	26	26	26	26	26	26	26	26	26	26	26	26
Thermoplastic Elastomer 1	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5	6.5
antioxidant	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6
lubricant	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2

The preparation method of the above-mentioned folding-resistant polypropylene composite material comprises the following steps:

Mix the components uniformly, melt extrude at 160-220°C through a twin-screw extruder, granulate, and dry to obtain the folding-resistant polypropylene composite material;

Among them, the aspect ratio of the twin-screw extruder is (36-48):1, the processing temperature is 160-220°C, the screw speed is 400-650rpm, and the feeding amount is 300-1000kg/h.

Result detection

Elongation at break, the test standard is ISO 527-2:2012, and the test condition is 50mm/min;

Izod notched impact strength, the test standard is ISO 180-2000, and the test condition is 23°C/1A;

Appearance inspection, fold 10^7 times, if the surface layer is broken, it will not pass, and if the surface layer is not broken, it will be passed.

The concrete detection result of each embodiment is described in following table 3:

Continued Table 3

The specific test results of each comparative example are described in Table 4 below:

Continued Table 4

It can be seen from the above data that the plastic hinge prepared by the folding-resistant polypropylene composite material of the present invention can have a breaking elongation rate as high as 525%, and the surface layer will not be damaged after being folded repeatedly 107 times, and the cantilever beam is also improved. Impact strength.

It can be seen from the above Comparative Example 1 and Example 1 that without the addition of impact copolymerized polypropylene, the elongation at break is far from reaching 525%, and the skin is cracked, failing the appearance test.

From the above Comparative Example 7 and Example 1, it can be seen that the molecular weight distribution index Mw/Mn of the metallocene polypropylene is too wide and the crystallinity is too high, which will adversely affect the elongation at break and the notched impact strength at room temperature. When the molecular weight distribution index is higher, the content of small molecular weight segments contained in metallocene PP is higher. From the perspective of molecular chain unwinding, small molecular chains are easier to untangle, so that the value of elongation at break is low. It shows that the surface layer of the hinge structure is cracked after repeated folding. When the crystallinity is too high, the amorphous region in the metallocene PP will naturally decrease, and the tendency of molecular chain stretching and orientation will become weaker on the microscopic level, and the macroscopic elongation at break will be low, resulting in molecular The surface layer of the chain structure is broken after repeated folding.

From the above Comparative Example 12 and Example 1, it can be seen that the molecular weight distribution index Mw/Mn of the impact copolymerized polypropylene is too narrow and the crystallinity is too high. , polypropylene with a high content of ethylene-propylene rubber is one of the components, but the crystallinity of this impact copolymer polypropylene is also high. When the crystallinity is too high, the increase and stability of the macroscopic elongation at break have not produced good results. The effect shows that the molecular weight distribution index, crystallinity, and ethylene-propylene rubber content of the impact copolymer polypropylene determined by the present invention must be controlled within a certain range, and the higher the three, the better.

It can be seen from Comparative Examples 7-18 that the properties of the metallocene polypropylene and the impact copolymer polypropylene are not within the scope of the present invention, and neither can achieve the effect of the present invention.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. A folding-resistant polypropylene composite material is characterized in that, in parts by weight, it comprises the following components:

   

   Wherein, the molecular weight distribution index Mw/Mn of the metallocene polypropylene is 2.3-2.7, the crystallinity is 32-38%, and the crystallinity test standard is ISO 11357-2016;

   The molecular weight distribution index Mw/Mn of the impact copolymerized polypropylene is 3.9 to 4.4, the degree of crystallinity is 31 to 37%, the test standard for the degree of crystallinity is ISO 11357-2016, and the mass content of ethylene-propylene rubber in the impact copolymerized polypropylene is 15-30%.
2. The anti-folding polypropylene composite material according to claim 1, is characterized in that, by weight, comprises the following components:

   

   The auxiliary agent is one or more of antioxidant, lubricant or toner.
3. The folding-resistant polypropylene composite material according to claim 1, wherein the crystallinity of the metallocene polypropylene is 34-36%.
4. The folding-resistant polypropylene composite material according to claim 1, wherein the crystallinity of the impact copolymer polypropylene is 32-35%, and the mass content of ethylene-propylene rubber in the impact copolymer polypropylene is 25-30%. .
5. The folding-resistant polypropylene composite material according to claim 1, wherein the melt mass flow rate of the metallocene polypropylene is 20-30g/10min, the test standard is ISO1133-2011, and the test condition is 230°C, 2.16 kg.
6. The folding-resistant polypropylene composite material according to claim 5, wherein the notched Izod impact strength of the impact copolymer polypropylene is 30-50 kJ/m ² , the test standard is ISO180-2000, and the test temperature is 23°C.
7. The folding-resistant polypropylene composite material according to claim 1, wherein the thermoplastic elastomer is an ethylene-octene copolymer, the crystallinity of the thermoplastic elastomer is 3 to 6%, and the test standard for the crystallinity is ISO 11357-2016.
8. The preparation method of the folding-resistant polypropylene composite material according to any one of claims 1 to 7, characterized in that it comprises the following steps:

   The components are uniformly mixed, melted and extruded by a twin-screw extruder at 160-220° C., granulated, and dried to obtain the folding-resistant polypropylene composite material.
9. The application of the folding-resistant polypropylene composite material in any one of claims 1 to 7 in the preparation of plastic hinges.
10. A plastic hinge, characterized in that the plastic hinge is prepared from the folding-resistant polypropylene composite material according to any one of claims 1-7.

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