Polypropylene injection foam molded body, method for producing the same, and use thereof

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a polypropylene injection foaming forming body, a preparation method and application thereof. The polypropylene injection foaming forming body, a polypropylene injection foaming material and a preset reinforcing sheet arranged in the polypropylene injection foaming material, wherein the preset reinforcing sheet comprises a polypropylene composite material; the polypropylene composite material comprises a plurality of polypropylene sheet layer unit groups which are sequentially stacked; the average value of the melting points of all outer layers in the i-th group is greater than or equal to the average value of the melting points of all outer layers in the (i-1)-th group. The polypropylene injection foaming forming body has low weight, high rigidity and impact toughness, that is, high vertical drop resistance, and has greatly improved compatibility compared with other non-polypropylene material preset reinforcing sheets on the market. In recycling, the polypropylene injection foaming forming body does not need to be separated and treated, and can be directly crushed and melted for regranulation application, thereby having a wide market prospect in the field of injection foaming technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a polypropylene injection foaming forming body and a preparation method and application thereof. BACKGROUND

[0002] It is known that there are four kinds of processes for polypropylene foaming, i.e. autoclave foaming, mold foaming, extrusion foaming and injection foaming. The foaming materials obtained by autoclave, mold and extrusion are all honeycomb continuous cell structures with very thin skin, and the common products have a ratio of 5 to 60 times. The autoclave injection foaming forming body, mold foaming plate and extrusion foaming sheet all need secondary processing to obtain the final parts. Injection foaming has a unique "sandwich" skin-core structure. It has a relatively thick and dense skin layer, and the cell structure is intermittent "island cell". The common weight reduction ratio is 3%-8%, and the parts can be formed at one time. Since the injection foaming product has good mechanical properties, it can be used in some structural load-bearing parts, and is therefore also called "structural foaming".

[0003] The injection foaming process brings a unique "sandwich" skin-core structure, excellent appearance quality, easy to spray color, and small loss of physical properties. The existence of uniform micropores not only reduces weight, but also helps to eliminate internal stress, thereby greatly reducing the shrinkage and warping degree of the parts and greatly improving the dimensional accuracy of the parts. At the same time, since there is gas in the melt during injection, the holding pressure time during molding is eliminated, which can effectively shorten the production cycle, improve the production efficiency, and reduce the clamping force. Compared with the technology of pre-placing sheet and ordinary injection molding, the foaming agent gas escaping in the mold during foaming can plasticize the surface of the pre-placed sheet, so that more layers of sheet can be compounded to achieve more ideal mechanical properties.

[0004] In order to further improve the production efficiency and physical properties of the injection foaming product, at present, a new process scheme is to first place an inorganic or organic reinforcing sheet in the mold, and then injection foaming molding in the mold, which is especially suitable for application in the field of automobile structural parts. In the existing technology, the pre-placed organic sheet mainly uses glass fiber reinforced nylon composite materials due to the high requirement for mechanical properties, so considering the compatibility problem, the injection foaming part can only use the same polyamide base resin as the pre-placed sheet, which has large density, long molding time, and is difficult to recycle after mixing with glass fiber. If a high-strength and high-impact polypropylene composite sheet is used as the pre-placed sheet, the same polypropylene composition as the pre-placed sheet can be used as the base resin of the injection foaming part, and the injection foaming product does not need to be separated and treated during recycling, and can be directly crushed and melted for regranulation application. However, the conventional polypropylene sheet is difficult to have both high strength and high impact, and the self-reinforced polypropylene composite sheet formed by multi-layer hot pressing often has small impact strength and interlayer peeling strength, and cannot obtain a hot-pressed composite material with good mechanical properties and high interlayer peeling strength. When the above polypropylene sheet is used as a pre-placed reinforcing sheet in a polypropylene injection foaming molding body, the vertical drop resistance of the polypropylene injection foaming molding body cannot meet the application requirements of the injection foaming molding body.

[0005] Therefore, how to provide a polypropylene injection foaming molding body which can not only reduce the weight of the foaming molding body, but also improve the vertical drop resistance, and is convenient to recycle, is a technical problem to be solved at present. SUMMARY

[0006] In view of the above problems of the prior art, the present application provides a polypropylene injection foaming molding body, which uses a high-strength and high-impact polypropylene composite sheet as a pre-placed sheet. The polypropylene injection foaming molding body has both low weight and high rigidity and impact toughness, that is, high vertical drop resistance. Compared with other pre-placed reinforcing sheets of non-polypropylene materials on the market, the compatibility is greatly improved, and the polypropylene injection foaming molding body does not need to be separated and treated during recycling, and can be directly crushed and melted for regranulation application, which has a broad market prospect in the field of injection foaming technology. Moreover, under the condition of similar weight reduction ratio, compared with the injection foaming molding body prepared by the conventional injection foaming process, the polypropylene injection foaming molding body of the present application not only can significantly improve the vertical drop resistance, but also can shorten the molding time and reduce the molding pressure, and has better processing performance.

[0007] In a first aspect, the object of the present application is to provide a polypropylene injection foaming molding body, comprising a polypropylene injection foaming material and a pre-placed reinforcing sheet arranged in the polypropylene injection foaming material, wherein the pre-placed reinforcing sheet comprises a polypropylene composite material.

[0008] The polypropylene composite material comprises a plurality of polypropylene sheet layer unit groups stacked in sequence; each polypropylene sheet layer unit group comprises at least one same or different polypropylene sheet layer unit, each polypropylene sheet layer unit comprises a core layer A i and outer layers B i on both sides of the core layer A i , B' i , and the structure is B i A i B' i ; the structure of the polypropylene composite material from bottom to top is the nth group, the (i-1)th group, the 2th group, the 1st group, the 2th group, the (i+1)th group, and the nth group in sequence, and the total number of the stacked polypropylene sheet layer unit groups is 2n-1; i and n are both integers not less than 2, and i≤n;

[0009] Among them, the core layer A i in the polypropylene sheet layer unit contains a polypropylene composition A i , the outer layers B i and the outer layers B' i are the same or different, each corresponding to containing a polypropylene composition B i , a polypropylene composition B' i ,

[0010] The melting point of the polypropylene composition A i is greater than the melting points of the polypropylene composition B i and the polypropylene composition B' i ; the average value of the melting points of all outer layers in the ith group is greater than or equal to the average value of the melting points of all outer layers in the (i-1)th group.

[0011] According to the present application, the preset reinforcing sheet comprises a polypropylene composite material, preferably, the preset reinforcing sheet is selected from a polypropylene composite material.

[0012] According to the present application, in the structure of the polypropylene composite material, the upper ith group and the lower ith group can be the same or different.

[0013] In a preferred embodiment of the present application, the difference between the melting point of the polypropylene composition A i and the melting point of the polypropylene composition B i , the difference between the melting point of the polypropylene composition A i and the melting point of the polypropylene composition B' i is each greater than or equal to 5°C, preferably greater than or equal to 10°C, more preferably greater than or equal to 20°C; more preferably 20-60°C.

[0014] According to the present application, the core layer in each polypropylene sheet unit can be the same material or different materials, and the present application has no particular limitation thereon, as long as A imelting point of the polypropylene composition B i , polypropylene composition B' i melting point, and the melting point of the polypropylene composition B

[0015] In a preferred embodiment of the present application, the difference between the average value of the melting points of all the outer layers in the ith group and the average value of the melting points of all the outer layers in the ith-1 group is the same or different, and each is 1-40°C, preferably 1-10°C, and more preferably 1-5°C.

[0016] According to the present application, the total number of the stacked groups of the polypropylene sheet layer unit groups is 2n-1, and the present application has a wide selection range for the total number of the stacked groups of the polypropylene sheet layer unit groups. In a preferred embodiment of the present application, 2≤n≤100 is selected, more preferably 2≤n≤50, and further preferably 2≤n≤30.

[0017] According to the present application, the number of the polypropylene sheet layer units included in each polypropylene sheet layer unit group has a wide selection range. In a preferred embodiment of the present application, each polypropylene sheet layer unit group, independently, includes 1 to 10, preferably 1 to 5, and more preferably 1 to 3, same or different polypropylene sheet layer units, and more preferably 1 polypropylene sheet layer unit. Preferably, the number of the polypropylene sheet layer units included in each polypropylene sheet layer unit group is the same.

[0018] Preferably but not necessarily, the melting point of any outer layer in each group is within ±10°C, preferably within ±5°C, and more preferably within ±3°C, and further preferably within ±1°C, of the average value of the melting points of all the outer layers in the group.

[0019] In the embodiment in which each polypropylene sheet layer unit group includes only 1 polypropylene sheet layer unit, for example, the structure of the polypropylene composite material can be B n A n B’ n …B i A i B’ i …B2A2B’2, B1A1B’1, B2A2B’2…B i A i B’ i …B n A n B’ n , the total number of the stacked layers of the polypropylene sheet layer units is 2n-1; i and n are each an integer not less than 2, and i≤n.

[0020] In the embodiment in which each polypropylene sheet layer unit group includes 2 or more polypropylene sheet layer units, for example, the structure of the ith polypropylene sheet layer unit group is B i1 A i1 B’i1 B i2 A i2 B’ i2 …B ip A ip B’ ip , the structure of the polypropylene composite material can be (B n1 A n1 B’ n1 , B n2 A n2 B’ n2 …B nq A nq B’ nq ) … (B i1 A i1 B’ i1 , B i2 A i2 B’ i2 …B ip A ip B’ ip ) … (B 21 A 21 B’ 21 , B 22 A 22 B’ 22 …B 2k A 2k B’ 2k ) (B 11 A 11 B’ 11 , B 12 A 12 B’ 12 …B 1j A 1j B’ 1j ) (B 21 A 21 B’ 21 , B 22 A 22 B’ 22 …B 2k A 2k B’ 2k ) … (B i1 A i1 B’ i1 , B i2 A i2 B’ i2 …B ip A ip B’ ip ) … (B n1 A n1 B’ n1 , B n2 An2 B’ n2 …B nq A nq B’ nq ), the total number of layers of the polypropylene sheet layer units is j+2k+…2p+…2q; j, k, p, q, each independently, is an integer not less than 2, preferably an integer of 2 to 10, more preferably an integer of 2 to 5, more preferably an integer of 2 to 3.

[0021] According to the present application, the thickness ratio of the core layer A i in each polypropylene sheet layer unit is selected in a wide range. In a preferred embodiment of the present application, the thickness of the core layer A i accounts for 51% to 89% of the total thickness, preferably 71% to 89%, further preferably 71% to 80% of the total thickness of each polypropylene sheet layer unit. i The thickness of the outer layers B i and B’ i on both sides can be the same or different, preferably the same.

[0022] The thickness of each polypropylene sheet layer unit is selected in a wide range. In a preferred embodiment of the present application, the thickness of each polypropylene sheet layer unit is 10 to 1000 μm, preferably 30 to 500 μm, further preferably 50 to 300 μm.

[0023] According to the present application, the thickness of the core layer A i , the outer layer B i , and the outer layer B i ’ can be controlled by the melt pump of the extruder during processing.

[0024] According to the present application, the polypropylene composition A i includes, but is not limited to, one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; the polypropylene compositions B i , B’ i each include, but are not limited to, one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene, and optionally a thermal adhesion enhancer y i .

[0025] According to the present application, the polypropylene composition A i is selected in a wide range. In a preferred embodiment of the present application, the polypropylene composition A i includes one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene.

[0026] In a more preferred embodiment of the present application, the polypropylene composition A i includes homopolymer polypropylene a iand impact copolymer polypropylene b i In a further more preferred embodiment of the present invention, the polypropylene composition A i Based on the total weight of i Contains 50-99 wt% of homopolymer polypropylene a i , 1-50wt% impact copolymer polypropylene b i ; Further preferably, the polypropylene composition A i Contains 70-90 wt% of homopolymer polypropylene a i , 10-30wt% impact copolymer polypropylene b i .

[0027] According to the present invention, the polypropylene composition B i , B' i Each comprises one or more of homopolymer polypropylene, random copolymer polypropylene and impact copolymer polypropylene; preferably the polypropylene composition B i and / or polypropylene composition B' i Also contains thermal bonding enhancer i .

[0028] In a more preferred embodiment of the present invention, the polypropylene composition B i , the polypropylene composition B' i Each comprising random copolymer polypropylene x i and thermal bonding enhancers i Preferably, the polypropylene composition B i , the polypropylene composition B' i Based on the total weight of each, the polypropylene composition B i , the polypropylene composition B' i Each comprising 70-99 wt% of random copolymerized polypropylene x i , 1-30wt% thermal bonding enhancer y i ; Preferably, the polypropylene composition B i Comprising 80-90 wt% of random copolymerized polypropylene x i , 10-20wt% thermal adhesion enhancer y i .

[0029] According to the present invention, the homopolymer polypropylene a i The selection range is relatively wide. In a preferred embodiment of the present invention, the homopolymer polypropylene a i The melting point is 150-170°C, preferably 160-170°C, and / or the isotacticity (mm) is not less than 96%, preferably not less than 97%, more preferably not less than 98%.

[0030] According to the present invention, the homopolymer polypropylene a i The melt flow rate selection range is relatively wide, preferably, the homopolymer polypropylene a i The melt flow rate at 230° C. and a load of 2.16 kg is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min.

[0031] According to the present invention, "and / or" refers to a situation where any one of the conditions can exist alone, or a situation where both conditions exist.

[0032] According to the present invention, the impact copolymer polypropylene b i The selection range is relatively wide. In a preferred embodiment of the present invention, the impact copolymer polypropylene b i The melting point is 150-170 ° C, the monomer of the impact-resistant copolymerized polypropylene and propylene is ethylene or butene, preferably butene, and / or the cantilever beam impact strength of the impact-resistant copolymerized polypropylene is not less than 20KJ / m 2 (23℃).

[0033] According to the present invention, the impact copolymer polypropylene b i The melt flow rate selection range is wide, preferably, the impact copolymer polypropylene b i The melt flow rate at 230° C. and a load of 2.16 kg is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min.

[0034] According to the research of the present inventors, when the polypropylene composition A i When the melt mass flow rate and polymer composition ratio of the raw materials used are within the preferred range, the impact copolymer polypropylene b in the composition i It can absorb the impact energy well, meet the requirements of impact performance, and make the sheet have good impact performance. i The medium and large molecular chain segments are relatively regular and crystallize during the sheet preparation process, so the sheet also has good tensile properties.

[0035] In a preferred embodiment of the present invention, the core layer A i It also contains a β-crystal nucleating agent; preferably, the β-crystal nucleating agent is selected from at least one of condensed ring aromatic hydrocarbons, Group IIA two-component complexes, aromatic diamides, rare earth compounds and cyclic dicarboxylates.

[0036] According to the present invention, the range of selection of the amount of the β-crystal nucleating agent is relatively wide. Preferably, the polypropylene composition A i The total amount is 100 parts by weight, the core layer Ai The content of the β crystal form nucleating agent is 0.01-0.5 parts by weight. Specifically, the content of the β crystal form nucleating agent can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 parts by weight.

[0037] In a preferred embodiment of the present application, the random copolymer polypropylene x i has a melting point of 110-150°C, preferably 120-140°C, preferably the average value of the melting points of all random copolymer polypropylenes in the i-th group is greater than the average value of the melting points of all random copolymer polypropylenes in the (i-1)-th group, preferably the difference between the melting points is 1-40°C, more preferably 1-10°C, most preferably 1-5°C; preferably, the random copolymer polypropylene x i is a copolymer of propylene and ethylene and / or butylene, preferably an ethylene-propylene-butylene terpolymer and / or a propylene-ethylene copolymer.

[0038] According to the present application, the random copolymer polypropylene x i has a wide range of melt flow rate, preferably the melt flow rate at 230°C under a load of 2.16 kg is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, further preferably 3-18 g / 10 min. The random copolymer polypropylene x i has a molecular weight distribution Mw / Mn of 5-12, preferably 7-10.

[0039] In a preferred embodiment of the present application, the heat adhesion enhancer y i has a melting point or viscous flow temperature of 70-110°C. And / or, the heat adhesion enhancer y i is selected from one or more of polyolefin elastomer, ethylene-propylene-diene rubber, SEBS, SBS, EVA, petroleum resin; preferably, the heat adhesion enhancer y i is polyolefin elastomer and / or petroleum resin.

[0040] In a preferred embodiment of the present application, the polyolefin elastomer is preferably a copolymer elastomer of ethylene and propylene and / or α-olefin, the α-olefin is preferably C4-C12 α-olefin, more preferably 1-butene and / or 1-octene; and / or, the petroleum resin is C5 and / or C9 hydrogenated petroleum resin, softening point is 100-150°C; preferably, it is a cyclopentadiene type resin.

[0041] According to the present application, the heat adhesion enhancer y i has a wide range of melt flow rate, preferably the melt flow rate of the heat adhesion enhancer y iThe melt flow rate at 190°C under a load of 2.16 kg is 0.5 to 50 g / 10 min, preferably 1 to 20 g / 10 min, preferably 1 to 18 g / 10 min, and further preferably 3 to 18 g / 10 min.

[0042] The inventors have found that when the polypropylene composition B i and the polypropylene composition B' i The low-melting random copolymer polypropylene x i and the thermal adhesion enhancer y i can significantly reduce the hot-pressing temperature and broaden the hot-pressing temperature window, and the thermal adhesion enhancer y i provides good adhesion properties for the sheet and further improves the interlayer peeling strength. The polypropylene composite as a pre-prepared reinforcing sheet makes the polypropylene injection foaming molded body of the present application have higher vertical drop resistance.

[0043] The inventors have found that when the polypropylene composition A i and the polypropylene composition B i and the polypropylene composition B' i The polymer composition A i and the polymer composition B i have a polymer composition ratio and a polymer composition A i thickness distribution within the above-mentioned preferred ranges, the sheet preparation process can be further stabilized, thereby making the sheet have further better uniformity, tensile strength, impact performance, and interlayer peeling strength. The polypropylene composite as a pre-prepared reinforcing sheet in this more preferred embodiment makes the polypropylene injection foaming molded body of the present application have further higher vertical drop resistance.

[0044] According to the present application, the polypropylene sheet can be a film or have a certain thickness. In the present application, the polypropylene film is one form of the polypropylene sheet.

[0045] According to the present application, the polypropylene sheet layer unit is a polypropylene sheet and / or a polypropylene fabric; the polypropylene sheet layer unit can be a polypropylene sheet or a polypropylene fabric. In a preferred embodiment of the present application, the polypropylene sheet layer unit is a polypropylene sheet or a polypropylene fabric.

[0046] In a preferred embodiment of the present application, the polypropylene sheet is obtained by co-extrusion of components containing the polypropylene composition A i , the polypropylene composition B i , and the polypropylene composition B' i .

[0047] In a preferred embodiment of the present application, the polypropylene fabric is prepared by first mixing the polypropylene composition Ai , polypropylene composition B i , polypropylene composition B' i The components including the polypropylene are co-extruded to obtain a polypropylene sheet, and the polypropylene sheet is then woven to obtain the polypropylene fabric; preferably, the polypropylene fabric has a three-dimensional structure of plain, twill and / or satin.

[0048] According to the present invention, preferably, the polypropylene sheet units are connected by hot pressing and bonding.

[0049] As an example, the polypropylene composite material is prepared by hot pressing multiple layers of the aforementioned polypropylene sheets or / and the aforementioned polypropylene fabrics; preferably, the polypropylene fabrics are stacked at 0-90° between the warp and the warp from top to bottom, preferably with more than or equal to 2 layers, more preferably 2-200 layers; most preferably 4-100 layers. The multiple layers of polypropylene sheets are stacked at 0-90° along their respective machine directions from top to bottom, preferably with more than or equal to 2 layers, more preferably 2-200 layers; most preferably 4-100 layers. The surface density of the multi-layer polypropylene composite material is greater than or equal to 110 g / m 2 , more preferably 110g / m 2 -14000g / m 2 ; Most preferably 220g / m 2 -7000g / m 2 In a preferred embodiment of the present invention, the polypropylene composition A contained in each layer of the stacked polypropylene fabric is i Can be the same or different, each layer contains polypropylene fabric A i Can be independently selected from, preferably each layer of polypropylene composition A i In a preferred embodiment of the present invention, the polypropylene composite material has at least one of the following characteristics:

[0050] Longitudinal tensile strength ≥150MPa, preferably ≥170MPa; more preferably longitudinal tensile strength ≥160MPa, further preferably ≥180MPa; interlayer peel strength ≥1N / mm, preferably ≥1.2N / mm; more preferably ≥1.3N / mm, further preferably ≥1.5N / mm.

[0051] The longitudinal tensile strength is measured according to the method specified in GB / T1040.1-2018, and the interlayer peel strength is measured according to the method specified in GB / T2358-98. The corresponding specimens in the above two tests are the standard specimens required by the above test standards.

[0052] When the polypropylene composite material is obtained by hot-pressing 5 polypropylene sheet layer units and the thickness of the polypropylene composite material is about 390 μm, the falling weight impact strength is ≥ 42 J, preferably ≥ 45 J.

[0053] The falling weight impact strength is determined according to the method specified in GB / T 14153-1993, and the thickness of the sample is the thickness of the product prepared.

[0054] According to the present application, the polypropylene composite material described above can be prepared by the following method, which comprises the step of sequentially stacking 2n-1 polypropylene sheet layer unit groups in the order of the nth group, the (i+1)th group, the 2nd group, the 1st group, the 2nd group, the (i+1)th group, the nth group, and then hot-pressing and fusing.

[0055] In the embodiment in which each polypropylene sheet layer unit group comprises only one polypropylene sheet layer unit, the preparation method comprises the step of sequentially stacking 2n-1 polypropylene sheet layer units of the structure B i A i B’ i in the order of B n A n B’ n B i A i B’ i B2A2B’2, B1A1B’1, B2A2B’2, B i A i B’ i B n A n B’ n and then hot-pressing and fusing.

[0056] In the embodiment in which each polypropylene sheet layer unit group comprises two or more polypropylene sheet layer units, the preparation method comprises the step of sequentially stacking the polypropylene sheet layer units of each polypropylene sheet layer unit group, and then sequentially stacking 2n-1 polypropylene sheet layer unit groups in the order of the nth group, the (i+1)th group, the 2nd group, the 1st group, the 2nd group, the (i+1)th group, the nth group, and then hot-pressing and fusing.

[0057] In a preferred embodiment of the present application, the preparation of the polypropylene composition A i comprises melt blending the raw materials, such as components including at least one of the homopolymer polypropylene, the random copolymer polypropylene and the impact copolymer polypropylene. i The conditions and equipment for melt blending are the same as those for melt blending of polyolefins in the prior art, and preferably the melt temperature is 190-240 °C, and the equipment is preferably a twin-screw extruder.

[0058] In a preferred embodiment of the present application, the polypropylene composition B i , B' i is prepared by melt blending the raw materials, such as components including at least one of the homopolymer polypropylene, the random copolymer polypropylene and the impact copolymer polypropylene; the polypropylene composition B i , B' i is prepared by melt blending the raw materials under the conditions and using the equipment of the prior art of polyolefin melt blending, preferably, the melt temperature is 190-240℃, and the equipment is preferably a twin-screw extruder.

[0059] In a preferred embodiment of the present application, the temperature of co-extrusion molding and casting is independently selected from 200-240℃; and / or, the temperature of calender roll is 50-70℃.

[0060] In a preferred embodiment of the present application, the conditions of stretching include: the temperature of stretching is 90-165℃, preferably 90-140℃, and further preferably 90-119℃; and / or, the stretching ratio is 1-15 times, preferably 2-9 times.

[0061] In a preferred embodiment of the present application, the width of the obtained polypropylene sheet is 2-5mm.

[0062] In a preferred embodiment of the present application, the hot-pressing conditions include: the hot-pressing temperature is 115-170℃, preferably 115-159℃, and further preferably 140-159℃; the hot-pressing pressure is 2-10MPa, the preheating time is 5-600s, and the hot-pressing time is 1-600s, preferably 10-500s.

[0063] In a preferred embodiment of the present application, the pressure of cooling setting is 2-8MPa, and the cooling time is 30s-700s.

[0064] In a preferred embodiment of the present application, the adjacent polypropylene fabrics of the stack are placed at 0-90° between the warp direction and the warp direction; and / or, the adjacent polypropylene sheets of the stack are placed at 0-90° along the respective machine direction, i.e. the stretching direction (MD).

[0065] According to the present application, the polypropylene injection foaming material contains at least one of the polypropylene composition A i and / or at least one of the polypropylene composition B i , the polypropylene composition B' i , and optional adjuvants.

[0066] The polypropylene injection foaming material contains the composition, and the polypropylene composition Ai and polypropylene composition B i The components can be mixed in any ratio between 0 and 100.

[0067] The auxiliary agent can be a common auxiliary agent in the art, and is preferably selected from one or more of an antioxidant, an antistatic agent, a lubricant, an anti-aging agent, and a colorant. As an example, one or more of the following processing aids commonly used in injection foam molding processes can be contained, such as, but not limited to:

[0068] Graphite colorant: 1-8% by weight, preferably 2-5% by weight; antioxidant: 0.1-15% by weight, preferably 0.1-5% by weight; antistatic agent: 0.1-10% by weight, preferably 0.5-5% by weight; lubricant: 0.1-10% by weight, preferably 0.5-3% by weight; anti-aging agent: 0.01-5% by weight, preferably 0.1-2% by weight. The content of the processing aids is well known in the art and will not be described here.

[0069] The polypropylene composition provided by the present application is prepared by the following method: after the components are measured according to the formula, they are added to a high-speed mixer, continuously stirred at high speed at room temperature for 1-10 minutes, preferably 2-5 minutes, and then added to a twin-screw extruder, extruded at 180-230°C, and pelletized.

[0070] When the polypropylene composition is formed into an injection foam molded body, a foaming agent is usually added. The polypropylene injection foam material contains a foaming agent and / or is foamed from an inorganic physical foaming agent; the foaming agent can be a chemical foaming agent or a physical foaming agent, and the physical foaming agent can be an organic physical foaming agent or an inorganic physical foaming agent. Examples of the chemical foaming agent include, but are not limited to, at least one of azodicarbonamide (AC foaming agent), p-toluenesulfonylhydrazide, aminoureas, tetrazoles, sodium bicarbonate, and sodium citrate. Examples of the organic physical foaming agent include, but are not limited to, at least one of aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclobutane and cyclohexane, and halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,2-difluoroethane, 1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride, and dichloromethane. Examples of the inorganic physical foaming agent include, but are not limited to, at least one of air, nitrogen, carbon dioxide, oxygen, and water.

[0071] Preferably, the inorganic physical foaming agent is selected from at least one of air, nitrogen, carbon dioxide, oxygen, and water; and / or, the foaming agent is selected from a chemical foaming agent and / or an organic physical foaming agent; more preferably, the chemical foaming agent is selected from at least one of azodicarbonamide, p-toluenesulfonylhydrazide, aminoureas, tetrazoles, sodium bicarbonate, and sodium citrate; and the organic physical foaming agent is selected from at least one of an aliphatic hydrocarbon foaming agent, an alicyclic hydrocarbon foaming agent, and a halogenated hydrocarbon foaming agent.

[0072] According to the present application, preferably, the number of the pre-positioned reinforcing sheets is at least two.

[0073] According to the present application, preferably, the most distal pre-positioned reinforcing sheets are respectively located outside the two ends of the injection-molded foamed body; more preferably, the distance between the pre-positioned reinforcing sheets inside the polypropylene injection-molded foamed body is 1.5-20 mm, preferably 2-10 mm.

[0074] Preferably, the number of the pre-positioned reinforcing sheets in the present application can be determined according to the size of the injection-molded body in combination with the preferred distance between the pre-positioned reinforcing sheets.

[0075] The conditions of injection foaming, such as injection pressure and time, are related to the shape and size of the product. According to the present application, when the injection mold involved in the examples and comparative examples of the present application is used, preferably, the conditions of injection foaming include: the injection pressure is not higher than 900 bar, preferably 750-900 bar; and / or, the production time is not higher than 250 s, preferably 210-250 s.

[0076] In a second aspect, the object of the present application is to provide a method for preparing the polypropylene injection-molded foamed body as described in the first aspect, comprising the following steps:

[0077] a. First, melt-mixing the base raw material comprising the polypropylene injection-molded foamed material to obtain a polypropylene composition for injection foaming;

[0078] b. Placing the pre-positioned reinforcing sheets in the mold, mixing the polypropylene composition for injection foaming with a foaming agent, if necessary, and injection foaming in the mold to form a polypropylene injection-molded foamed material to obtain the polypropylene injection-molded foamed body.

[0079] The polypropylene injection-molded foamed body of the present application is formed by one-time molding in an injection mold from the polypropylene composite material (sheet) described above and the base raw material of the polypropylene injection-molded foamed material.

[0080] According to some embodiments of the present application, the injection foaming device used is composed of the injection foaming special machine KMGX650-4300 of KraussMaffei and the supercritical gas controller T-300L of TREXEL company. The conditions of using the injection foaming device in the present application can be the conventional selection in the art, either physical foaming or chemical foaming can be used. The specific process is known to those skilled in the art, and is not described here.

[0081] According to some embodiments of the present application, the injection mold used can be used to make a 500mm*500mm turnover box splicing plate. The appearance of the mold is shown inFigure 1 The appearance of the product is shown in the accompanying drawings Figure 2 The conditions for the injection foaming mold of the present application can be conventional choices in the art, and the specific process is known to those skilled in the art, which is not described here.

[0082] The conditions for the injection foaming, such as injection pressure and time, are related to the shape and size of the product. According to the present application, when the injection mold involved in the examples and comparative examples of the present application is used, preferably, the conditions for the injection foaming include: the injection pressure is not higher than 900 bar, preferably 750-900 bar; and / or, the production time is not higher than 250 s, preferably 210-250 s.

[0083] According to the present application, the temperature conditions during the injection foaming are that the melt temperature is 230℃, and the mold temperature is 50℃, which are both conventional technical conditions in the art, and are not described here in the examples and comparative examples.

[0084] Compared with the conventional injection foaming molded body of the same shape and the same base resin, the injection foaming molded body of the present application can reduce the single-mold production time by 5%-45%, preferably between 15%-30%.

[0085] Compared with the conventional injection foaming molded body of the same shape and the same base resin, the injection foaming molded body of the present application can reduce the injection pressure by 5%-50%, preferably between 10%-30%.

[0086] In a third aspect, the object of the present application is to provide the use of the polypropylene injection foaming molded body of the first aspect or the polypropylene injection foaming molded body prepared by the preparation method of the second aspect as a material in at least one of the following fields: automobile, communication, airplane, logistics, heat preservation, precision machinery and electronic turnover, packaging.

[0087] Compared with the prior art, the present application has the following beneficial effects:

[0088] (1) The injection foaming molded body of the present application has significantly improved impact resistance compared with the injection foaming molded body of the same shape and the same weight reduction ratio of the same base resin. According to the GB4857.5 packaging and transportation packaging piece drop internal test method, the drop height can be up to 1200mm without deformation and damage, and preferably up to 1500mm without deformation and damage. Compared with the injection molded body of the same volume of the same base resin, the injection foaming molded body of the present application has a weight reduction ratio of ≥3%, preferably ≥6%.

[0089] (2) The polypropylene injection foaming molded body provided by the present application is prepared by prepositioning a high-strength and high-impact polypropylene composite sheet in an injection molding mold, and one-time molding a polypropylene composition with the same base resin of the sheet in the injection molding mold by an injection foaming process.

[0090] (3) The present application can significantly improve the physical properties of the product by pre-setting the sheet, compared with the commonly used injection foaming forming body.

[0091] (4) The compatibility between the pre-set sheet and the base resin is greatly improved, which can effectively reduce the weight of the product and improve the production efficiency, compared with the commonly used glass fiber nylon composite pre-set sheet or metal sheet reinforced forming body of the composite reinforced injection foaming forming body.

[0092] (5) The polypropylene injection foaming forming body of the present application can be prepared by using various existing injection foaming processes, and different process methods and different types of foaming agents can be used to prepare polypropylene composition injection foaming forming bodies with different properties according to the needs of downstream applications.

[0093] (6) The polypropylene injection foaming forming body of the present application is a uniform component, which does not need to be separated and treated during recycling, and can be directly used in other processing application fields after crushing and melting granulation, and the recycling cost is lower.

[0094] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0095] Figure 1 is the mold used for preparing the injection molding of the examples and comparative examples;

[0096] Figure 2 is the injection foaming forming body obtained from Example 1. DETAILED DESCRIPTION

[0097] The present application will be specifically described below in combination with specific embodiments. It is necessary to point out here that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still fall within the protection scope of the present application.

[0098] In the following examples and comparative examples:

[0099] The extrusion calender machine and the solid phase drawing equipment are purchased from Tianjin Hengrui Company, and the model is HRPC-800 three-layer co-extrusion plastic drawing sheet production line.

[0100] The properties of the polypropylene composition and the sheet are tested according to the following methods:

[0101] (1) Melt mass flow rate (MFR): determined according to the method specified in GB / T 3682-2000, wherein the test temperature is 230℃, and the load is 2.16kg;

[0102] (2) Density, measured according to the method specified in GB / T 1033.1-2008;

[0103] (3) Melting point, measured according to the method specified in GB / T 28724-2012;

[0104] (4) Tensile strength: measured according to the method specified in GB / T1040.1-2018;

[0105] (5) Falling dart impact strength: measured according to the method specified in GB / T14153-1993;

[0106] (6) Interlayer peeling strength: measured according to the method specified in QB / T2358-98.

[0107] The performance of the polypropylene injection foaming formed body is tested according to the following method:

[0108] Impact strength of the injection foaming mechanical formed body:

[0109] According to the test method specified in GB4857.5 Package Transport Package Drop;

[0110] In the following examples, the β crystal form nucleating agent with the trade name VP101B is from Beijing Research Institute of Chemical Industry; the sources of some raw materials are recorded in the examples, and the rest of the raw materials are commercially available products if no special instructions are given.

[0111] Example 1

[0112] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extrusion polypropylene sheet, the polypropylene fabric, the polypropylene composite material, the polypropylene composition, and the polypropylene composition injection foaming formed body provided by the application.

[0113] (1) Preparation of the polypropylene composition A:

[0114] Component a is a homopolymer polypropylene made by Beijing Research Institute of Chemical Industry of Sinopec, with a melting point of 160℃, a melt flow rate (melt mass flow rate) of 3.2g / 10min, and an isotacticity of 97%; component b is a polypropylene impact copolymer made by Beijing Research Institute of Chemical Industry of Sinopec, with an ethylene content of 11wt%, a melting point of 155℃, a cantilever beam impact strength of 23KJ / m 2 (23℃), and a melt flow rate of 2.0g / 10min. The above prepared components are weighed and mixed according to the ratio, wherein the mass fraction Wa of component a is 80 parts by weight, and the mass fraction Wb of component b is 20 parts by weight.

[0115] The β crystal nucleating agent with trade name VP101B was added in an amount of 0.05 parts by weight. Then the mixture was added into a high speed mixer for mixing, and then the mixed material was added into a feeder of a twin-screw extruder made by W&P Company, and the material was fed into the twin screw through the feeder. The temperature of the screw during the process was kept at 200-230°C. The material was melt-mixed, extruded, pelletized and dried to obtain polypropylene composition pellets A. The melting point of the polypropylene composition pellets A was 157°C.

[0116] (2) Preparation of polypropylene composition B i

[0117] Component xi was a random copolymer polypropylene made by Beijing Research Institute of Chemical Industry, SINOPEC, which was an ethylene-propylene-butene terpolymer, with a molecular weight distribution Mw / Mn of 8.9, a melt flow rate of 8.1 g / 10 min, and a melting point of 130°C. Component x2 was a random copolymer polypropylene made by Beijing Research Institute of Chemical Industry, SINOPEC, which was an ethylene-propylene-butene terpolymer, with a molecular weight distribution Mw / Mn of 7.6, a melt flow rate of 7.2 g / 10 min, and a melting point of 135°C. Component x3 was a random copolymer polypropylene made by Beijing Research Institute of Chemical Industry, SINOPEC, which was an ethylene-propylene-butene terpolymer, with a molecular weight distribution Mw / Mn of 7.3, a melt flow rate of 6.6 g / 10 min, and a melting point of 140°C. Component y was a polyolefin elastomer with trade name 6102, which was purchased from Exxon Company, and was an ethylene-propylene copolymer.

[0118] The components prepared above were weighed and mixed according to the ratio, wherein the mass fraction of component xi was 85 parts by weight, and the mass fraction of component y was 15 parts by weight. The other steps were the same as step (1), and finally polypropylene composition B was obtained. i Pellets (i.e. xi+y=B i , i=1, 2, 3). It was detected that the melting point of B1 was 127°C, the melting point of B2 was 132°C, and the melting point of B3 was 138°C.

[0119] (3) Preparation of three-layer co-extruded polypropylene sheet

[0120] The polypropylene composition A and polypropylene composition B i pellets prepared in step (1) and step (2) above were dried. Then the polypropylene composition A was added into a core layer extruder for multi-layer extrusion calendering, and the polypropylene composition B i ​The polypropylene composition A 5 kg and the polypropylene composition B 3 pellets 5 kg prepared in the above step (1) and (2) were added with 30 g of antioxidant 1010, 100 g of 2000 mesh commercially available talc, and 200 g of commercially available graphite color powder, and then mixed for 3 minutes by a high-speed stirring machine. A double screw extruder was used for granulation, the die temperature was 220 °C, the screw rotation speed was 300 rpm, and the torque was 60%, to obtain a polypropylene mixture AB.

[0121] The composite film (polypropylene sheet) prepared after stretching and winding was composed of an upper surface layer (outer film B i ), a core layer (film A), and a lower surface layer (outer film B i ). The thickness of the composite film was 80 μm, and the thickness of the film layer A accounted for 80% of the total thickness of the sheet.

[0122] (4) Preparation of polypropylene fabric:

[0123] The three-layer co-extruded polypropylene sheet prepared in the above step (3) was cut by a high-speed slitting machine with multiple blades to obtain an oriented polypropylene ribbon with a width of 3 mm. The oriented ribbon was woven according to the designed fabric structure by using a commercial weaving machine to prepare plain polypropylene fabrics B1AB1, B2AB2, and B3AB3.

[0124] (5) Preparation of polypropylene composite material: The polypropylene fabric prepared in the above step (4) was stacked in order from bottom to top as B3AB3, B2AB2, B1AB1, B2AB2, B3AB3, and the total number of layers was 5. The stacked polypropylene fabric was hot-pressed and fused, and then cooled and shaped to prepare a polypropylene composite material. The polypropylene fabric was placed in the warp direction at an angle of 90° between the warp and weft directions. The hot-pressing conditions used were: temperature 145 °C, hot-pressing pressure 5 MPa, preheating time 90 s, hot-pressing time 90 s, and cooling time 300 s. The thickness of the prepared polypropylene composite material was 391 μm.

[0125] It was detected that the drop hammer impact strength of the polypropylene composite material was greater than 45 J, the longitudinal tensile strength was greater than 180 MPa, and the interlayer peeling strength was greater than 1.5 N / mm.

[0126] (6) Preparation of polypropylene composition for injection molding and foaming:

[0127] The polypropylene composition A 5 kg and the polypropylene composition B 3 pellets 5 kg prepared in the above step (1) and (2) were added with 30 g of antioxidant 1010, 100 g of 2000 mesh commercially available talc, and 200 g of commercially available graphite color powder, and then mixed for 3 minutes by a high-speed stirring machine. A double screw extruder was used for granulation, the die temperature was 220 °C, the screw rotation speed was 300 rpm, and the torque was 60%, to obtain a polypropylene mixture ABi The melt flow rate MFRB was 4.9 g / 10 min and the melting point was 151°C.

[0128] (7) Preparation of polypropylene injection foamed body

[0129] The polypropylene composition AB prepared in the above step (6) is prepared on a physical micro-foaming special injection molding machine. i -1 is the matrix resin, and the polypropylene composite material obtained in the above step (4) is the pre-set reinforcement sheet. Figure 1 As shown in the figure, six square sheets (pre-installed reinforcement sheets) with a side length of 100 mm are hung in the center of the mold with a size of 500 mm * 500 mm * 24 mm on the left and right cavities, with a spacing of 4.2 mm between the sheets. The two outermost sheets are located outside the injection foam molding after injection molding. The injection molding machine is turned on to feed the material. i -1 fills the injection screw and melts and homogenizes, then injects 99.99% nitrogen as a supercritical physical foaming agent into the screw homogenization zone, and the supercritical nitrogen and the polypropylene composition AB are sheared by the screw. i The mixture was mixed into a single-phase melt, which was then injected into the mold cavity via a self-locking nozzle. The mold was opened to release the pressure and gas to escape, resulting in an injection-molded foamed polypropylene composition. The weight loss ratio, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0130] Example 2

[0131] This example is used to illustrate the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, polypropylene composite material, polypropylene composition and polypropylene composition injection-molded foamed article provided by the present invention.

[0132] (1) Preparation of polypropylene composition A:

[0133] Component a is a homopolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, with a melting point of 165°C, a melt flow rate of 8.1g / 10min, and an isotacticity of 97%. Component b is a polypropylene impact copolymer produced by Sinopec Beijing Research Institute of Chemical Industry, with an ethylene content of 8wt%, a melting point of 155°C, a melt flow rate of 3.2g / 10min, and an Izod impact strength of 25KJ / m 2(23°C). The components prepared above were weighed and mixed according to the ratio, wherein the mass fraction of component a is 70 parts by weight, and the mass fraction of component b is 30 parts by weight. A β crystal nucleating agent with a brand of VP101B was added in an amount of 0.05 parts by weight. Then the mixture was mixed uniformly in a high-speed mixer, and then the mixed material was fed into the feeder of a twin-screw extruder manufactured by W&P Company, and the material entered the twin screw through the feeder. The temperature of the screw during the process was maintained at 200-230°C. After melting, mixing, extruding, granulating and drying, polypropylene composition granules A were obtained. It was detected that the melting point of the polypropylene composition granules A was 161°C.

[0134] (2) Preparation of polypropylene composition B i

[0135] Component x1 is a random copolymer polypropylene prepared by Beijing Research Institute of Chemical Industry, SINOPEC, which is an ethylene-propylene-butene terpolymer, the molecular weight distribution Mw / Mn is 8.4, the melting point is 128°C, and the melt flow rate is 7.8 g / 10 min; component x2 is a random copolymer polypropylene prepared by Beijing Research Institute of Chemical Industry, SINOPEC, which is an ethylene-propylene-butene terpolymer, the molecular weight distribution Mw / Mn is 7.6, the melting point is 134°C, and the melt flow rate is 6.9 g / 10 min; component x3 is a random copolymer polypropylene prepared by Beijing Research Institute of Chemical Industry, SINOPEC, which is an ethylene-propylene-butene terpolymer, the molecular weight distribution Mw / Mn is 7.1, the melting point is 142°C, and the melt flow rate is 5.2 g / 10 min; component y is a polyolefin elastomer with a brand prepared by Beijing Research Institute of Chemical Industry, SINOPEC, which is an ethylene-propylene copolymer, the ethylene content is 15%wt, the melting point is 105°C, and the melt flow rate under a load of 2.16 kg is 9 g / 10 min.

[0136] The components prepared above were weighed and mixed according to the ratio, wherein the mass fraction of component xi is 80 parts by weight, and the mass fraction of component y is 20 parts by weight, and the other steps are the same as step (1). Finally, polypropylene composition B was obtained. i i It was detected that the melting point of B1 was 126°C, the melting point of B2 was 133°C, and the melting point of B3 was 140°C.

[0137] (3) Preparation of a three-layer co-extruded polypropylene sheet

[0138] The preparation process was the same as step (3) of Example 1.

[0139] (4) Preparation of a polypropylene fabric

[0140] The preparation process was the same as step (4) of Example 1.​​

[0141] (5) Preparation of polypropylene composite:

[0142] The preparation procedure is the same as step (5) of Example 1.

[0143] The thickness of the prepared polypropylene composite is close to that of Example 1.

[0144] (6) Preparation of polypropylene composition for injection molding foaming:

[0145] The preparation procedure is the same as step (6) of Example 1, and polypropylene mixture AB is obtained. i -2, wherein B i is B3 in this example. It is detected that the melt mass flow rate MFRB= 8.8 g / 10 min, and the melting point is 158°C

[0146] (7) Preparation of polypropylene injection molding foaming body

[0147] The preparation procedure is the same as step (7) of Example 1, except that the polypropylene composition AB obtained in the above step (6) i -2 is used as the matrix resin, and a polypropylene composition injection molding foaming body is obtained. The weight loss ratio, drop height, production time and injection molding pressure are measured, and the results are shown in Table 1.

[0148] Example 3

[0149] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extruded polypropylene sheet, the polypropylene fabric, the polypropylene composite, the polypropylene composition and the polypropylene composition injection molding foaming body provided by the present application.

[0150] (1) Preparation of polypropylene composition A:

[0151] The preparation procedure is the same as step (1) of Example 1.

[0152] (2) Preparation of polypropylene composition B i :

[0153] The preparation procedure is the same as step (2) of Example 1.

[0154] (3) Preparation of three-layer co-extruded polypropylene sheet:

[0155] The main steps are the same as Example 1. The thickness of the polypropylene sheet is 80 μm, and the thickness ratio of the film layer A to the total thickness of the sheet is 90%.

[0156] (4) Preparation of polypropylene fabric:

[0157] The preparation procedure is the same as step (4) of Example 1.

[0158] (5) Preparation of polypropylene composite:

[0159] The preparation process was the same as step (5) of Example 1.

[0160] The thickness of the prepared polypropylene composite was close to that of Example 1.

[0161] (6) Preparation of polypropylene composition for injection foaming:

[0162] The preparation process was the same as step (6) of Example 1.

[0163] (7) Preparation of polypropylene injection foaming molded body

[0164] The preparation process was the same as step (7) of Example 1, and a polypropylene composition injection foaming molded body was obtained. The weight, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0165] Example 4

[0166] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extrusion polypropylene sheet, the polypropylene fabric, the polypropylene composite, the polypropylene composition, and the polypropylene composition injection foaming molded body provided by the present application.

[0167] (1) Preparation of polypropylene composition A:

[0168] The preparation process was the same as step (1) of Example 1.

[0169] (2) Preparation of polypropylene composition B i

[0170] The preparation process was the same as step (2) of Example 1.

[0171] (3) Preparation of three-layer co-extrusion polypropylene sheet:

[0172] The main preparation process was the same as step (3) of Example 1. The sheet stretch ratio was 10 times.

[0173] (4) Preparation of polypropylene fabric:

[0174] The preparation process was the same as step (4) of Example 1.

[0175] (5) Preparation of polypropylene composite:

[0176] The preparation process was the same as step (5) of Example 1.

[0177] The thickness of the prepared polypropylene composite was close to that of Example 1.

[0178] (6) Preparation of polypropylene composition for injection foaming:

[0179] ​The preparation procedure was the same as step (6) of Example 1.

[0180] (7) Preparation of polypropylene injection-foamed molded body

[0181] The preparation procedure was the same as step (7) of Example 1 to obtain a polypropylene composition injection-foamed molded body. Its weight, drop height, production time and injection pressure were measured, and the results are shown in Table 1.

[0182] Example 5

[0183] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extruded polypropylene sheet, the polypropylene fabric, the polypropylene composite material, the polypropylene composition and the polypropylene composition injection-foamed molded body provided by the present application.

[0184] (1) Preparation of polypropylene composition A:

[0185] The preparation procedure was the same as step (1) of Example 1.

[0186] (2) Preparation of polypropylene composition B i

[0187] The preparation procedure was the same as step (2) of Example 1.

[0188] (3) Preparation of three-layer co-extruded polypropylene sheet:

[0189] The preparation procedure was the same as step (3) of Example 1.

[0190] (4) Preparation of polypropylene fabric:

[0191] The preparation procedure was the same as step (4) of Example 1.

[0192] (5) Preparation of polypropylene composite material:

[0193] The main steps were the same as Example 1. Two layers of polypropylene fabric were included in the laminated polypropylene sheet. The hot-pressing conditions used were: temperature 140°C, hot-pressing pressure 2 MPa, preheating time 120 s, hot-pressing time 10 s, and cooling time 300 s. The thickness of the prepared polypropylene composite material was 128 μm.

[0194] (6) Preparation of polypropylene composition for injection foaming:

[0195] The preparation procedure was the same as step (6) of Example 1.

[0196] (7) Preparation of polypropylene injection-foamed molded body

[0197] The preparation procedure was the same as step (7) of Example 1 to obtain a polypropylene composition injection-foamed molded body. Its weight, drop height, production time and injection pressure were measured, and the results are shown in Table 1.​

[0198] Example 6

[0199] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extruded polypropylene sheet, the polypropylene fabric, the polypropylene composite material, the polypropylene composition and the polypropylene composition injection-molded foamed body provided by the present application.

[0200] (1) Preparation of the polypropylene composition A:

[0201] The preparation process is the same as step (1) of Example 1.

[0202] (2) Preparation of the polypropylene composition B: i

[0203] The preparation process is the same as step (2) of Example 1.

[0204] (3) Preparation of the three-layer co-extruded polypropylene sheet:

[0205] The preparation process is the same as step (3) of Example 1.

[0206] (4) Preparation of the polypropylene composite material:

[0207] The preparation of the polypropylene fabric is not performed, and the three-layer co-extruded polypropylene sheet prepared in step (3) is used to replace the polypropylene fabric obtained in step (4) of Example 1, and the sequential lamination and hot pressing are performed according to step (5) of Example 1. The prepared polypropylene composite material has a thickness of 0.39 mm.

[0208] (5) Preparation of the polypropylene composition for injection-molded foaming:

[0209] The preparation process is the same as step (6) of Example 1.

[0210] (6) Preparation of the polypropylene injection-molded foamed body

[0211] The preparation process is the same as step (7) of Example 1, and the polypropylene composition injection-molded foamed body is obtained. The weight, drop height, production time and injection-molding pressure are measured, and the results are shown in Table 1.

[0212] Example 7

[0213] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extruded polypropylene sheet, the polypropylene fabric, the polypropylene composite material, the polypropylene composition and the polypropylene composition injection-molded foamed body provided by the present application.

[0214] (1) Preparation of the polypropylene composition A:

[0215] The preparation process is the same as step (1) of Example 1.

[0216] ​(2) Preparation of polypropylene composition B i (3) Preparation of three-layer co-extruded polypropylene sheet

[0217] The preparation process is the same as step (2) of Example 1.

[0218] (3) Preparation of three-layer co-extruded polypropylene sheet

[0219] The preparation process is the same as step (3) of Example 1.

[0220] (4) Preparation of polypropylene fabric

[0221] The preparation process is the same as step (4) of Example 1.

[0222] (5) Preparation of polypropylene composite material

[0223] The preparation process is the same as step (5) of Example 1.

[0224] The thickness of the prepared polypropylene composite material is close to that of Example 1.

[0225] (6) Preparation of polypropylene composition for injection molding foaming

[0226] The preparation process is the same as step (6) of Example 1, except that 9.5 kg of polypropylene composition A prepared in step (1) and 0.5 kg of polypropylene composition B3 pellets prepared in step (2) are used. The melt mass flow rate MFRA of the polypropylene composition AB i is 4.6 g / 10 min; and the melting point of the polypropylene composition AB i -3 is 157°C.

[0227] (7) Preparation of polypropylene injection molding foaming formed body

[0228] The preparation process is the same as step (7) of Example 1, and a polypropylene composition injection molding foaming formed body is obtained. The weight, drop height, production time, and injection molding pressure are measured, and the results are shown in Table 1.

[0229] Example 8

[0230] This example is used to illustrate the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, polypropylene composite material, polypropylene composition, and polypropylene composition injection molding foaming formed body provided by the present application.

[0231] (1) Preparation of polypropylene composition A

[0232] The preparation process is the same as step (1) of Example 1.

[0233] (2) Preparation of polypropylene composition B i (3) Preparation of three-layer co-extruded polypropylene sheet

[0234] The preparation process is the same as step (2) of Example 1.

[0235] (3) Preparation of a three-layer co-extruded polypropylene sheet:

[0236] The preparation procedure was the same as step (3) of Example 1.

[0237] (4) Preparation of a polypropylene fabric:

[0238] The preparation procedure was the same as step (4) of Example 1.

[0239] (5) Preparation of a polypropylene composite:

[0240] The preparation procedure was the same as step (5) of Example 1.

[0241] The thickness of the prepared polypropylene composite was close to that of Example 1.

[0242] (6) Preparation of a polypropylene composition for injection molding and foaming:

[0243] The preparation procedure was the same as step (6) of Example 1, except that 0.5 kg of the polypropylene composition A prepared in step (1) above and 9.5 kg of the polypropylene composition B pellets prepared in step (2) were used. The melt mass flow rate MFR of the polypropylene composition AB was measured to be 5.2 g / 10 min. i The melting point of the polypropylene composition AB-4 was 138°C.

[0244] (7) Preparation of a polypropylene injection-molded and foamed shaped body

[0245] The preparation procedure was the same as step (7) of Example 1, and a polypropylene composition injection-molded and foamed shaped body was obtained. The weight, drop height, production time, and injection-molding pressure of the shaped body were measured, and the results are shown in Table 1.

[0246] Example 9

[0247] This example is used to illustrate the preparation of the polypropylene composition, the three-layer co-extruded polypropylene sheet, the polypropylene fabric, the polypropylene composite, the polypropylene composition, and the polypropylene composition injection-molded and foamed shaped body provided by the present application.

[0248] (1) Preparation of a polypropylene composition A:

[0249] The preparation procedure was the same as step (1) of Example 1.

[0250] (2) Preparation of a polypropylene composition B i

[0251] The preparation procedure was the same as step (2) of Example 1.

[0252] (3) Preparation of a three-layer co-extruded polypropylene sheet:

[0253] ​The preparation process is the same as step (3) of Example 1.

[0254] (4) Preparation of polypropylene fabric:

[0255] The preparation process is the same as step (4) of Example 1.

[0256] (5) Preparation of polypropylene composite:

[0257] The preparation process is the same as step (5) of Example 1.

[0258] The thickness of the prepared polypropylene composite is close to that of Example 1.

[0259] (6) Preparation of polypropylene composition for injection molding foaming:

[0260] The preparation process is the same as step (6) of Example 1.

[0261] (7) Preparation of polypropylene injection molding foaming body

[0262] The preparation process is the same as step (7) of Example 1, except that 3 square sheets with a side length of 100 mm are hung in the left and right cavities of the mold, with a spacing of 12 mm, and the two outermost sheets are located outside the injection molding foaming body after injection molding foaming, to obtain a polypropylene composition injection molding foaming body. The weight, drop height, production time, and injection pressure are measured, and the results are shown in Table 1.

[0263] Example 10

[0264] This example is used to illustrate the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, polypropylene composite, polypropylene composition, and polypropylene composition injection molding foaming body provided by the present application.

[0265] (1) Preparation of polypropylene composition A:

[0266] The preparation process is the same as step (1) of Example 1.

[0267] (2) Preparation of polypropylene composition B i

[0268] The preparation process is the same as step (2) of Example 1.

[0269] (3) Preparation of three-layer co-extruded polypropylene sheet:

[0270] The preparation process is the same as step (3) of Example 1.

[0271] (4) Preparation of polypropylene fabric:

[0272] The preparation process is the same as step (4) of Example 1.

[0273] ​(5) Preparation of polypropylene composite

[0274] The preparation procedure was the same as step (5) of Example 1.

[0275] The thickness of the prepared polypropylene composite was close to that of Example 1.

[0276] (6) Preparation of polypropylene composition for injection molding foaming

[0277] The preparation procedure was the same as step (6) of Example 1.

[0278] (7) Preparation of polypropylene injection molding foaming body

[0279] The preparation procedure was the same as step (7) of Example 1, except that 11 square sheets with a side length of 100 mm were respectively hung in the left and right cavities of the mold with a spacing of 2 mm, and the two outermost sheets were located outside the injection molding foaming body after injection molding foaming, to obtain a polypropylene composition injection molding foaming body. The weight, drop height, production time and injection pressure were determined, and the results are shown in Table 1.

[0280] Comparative Example 1

[0281] A three-layer co-extruded polypropylene sheet was prepared according to the method of Example 1. Only polypropylene composition A was used to extrude a single-layer film with a thickness of 80 μm.

[0282] A polypropylene fabric and a polypropylene composite were prepared according to the method of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0283] The preparation procedure of the polypropylene composition for injection molding foaming was the same as step (6) of Example 1, except that only polypropylene composition A was used. The preparation procedure of the polypropylene injection molding foaming body was the same as step (7) of Example 1, to obtain a polypropylene composition injection molding foaming body. The weight, drop height, production time and injection pressure were determined, and the results are shown in Table 1.

[0284] Comparative Example 2

[0285] A three-layer co-extruded polypropylene sheet was prepared according to the method of Example 1. Only polypropylene composition B3 was used to extrude a single-layer film with a thickness of 80 μm.

[0286] A polypropylene fabric and a polypropylene composite were prepared according to the method of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0287] The polypropylene composition for injection molding and foaming was prepared according to the procedure of step (6) of Example 1 except that only the polypropylene composition B3 was used. The polypropylene injection molded and foamed shaped body was prepared according to the procedure of step (7) of Example 1 to obtain a polypropylene composition injection molded and foamed shaped body. The weight, drop height, production time and injection molding pressure were measured and the results are shown in Table 1.

[0288] Comparative Example 3

[0289] A three-layer co-extruded polypropylene sheet was prepared according to the procedure of Example 1 except that only component b was contained in the polypropylene composition A.

[0290] A polypropylene fabric and a polypropylene composite were prepared according to the procedure of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0291] The polypropylene composition for injection molding and foaming was prepared according to the procedure of step (6) of Example 1 except that only component b was contained in the polypropylene composition A. The polypropylene injection molded and foamed shaped body was prepared according to the procedure of step (7) of Example 1 to obtain a polypropylene composition injection molded and foamed shaped body. The weight, drop height, production time and injection molding pressure were measured and the results are shown in Table 1.

[0292] Comparative Example 4

[0293] A three-layer co-extruded polypropylene sheet was prepared according to the procedure of Example 1 except that only component y was contained in the polypropylene composition B i .

[0294] A polypropylene fabric and a polypropylene composite were prepared according to the procedure of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0295] The polypropylene composition for injection molding and foaming was prepared according to the procedure of step (6) of Example 1 except that only component y was contained in the polypropylene composition B i . The polypropylene injection molded and foamed shaped body was prepared according to the procedure of step (7) of Example 1 to obtain a polypropylene composition injection molded and foamed shaped body. The weight, drop height, production time and injection molding pressure were measured and the results are shown in Table 1.

[0296] Comparative Example 5

[0297] A co-extruded polypropylene sheet was prepared according to the procedure of Example 6 except that component B iThe materials are selected in the following way: component x1 is a random copolymer polypropylene made by SINOPEC Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer, and has a melting point of 140°C; component x2 is a random copolymer polypropylene made by SINOPEC Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer, and has a melting point of 135°C; component x3 is a random copolymer polypropylene made by SINOPEC Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer, and has a melting point of 130°C; the melt flow rates of components x1-x3 are all in the range of 2-10 g / 10 min.

[0298] The polypropylene composition B is finally obtained i The pellets (i.e. x i +y = B i , i = 1, 2, 3), and it is detected that the melting point of B1 is 138°C, the melting point of B2 is 132°C, and the melting point of B3 is 127°C.

[0299] The polypropylene fabric and the polypropylene composite material are prepared according to the method of Example 1. The thickness of the prepared polypropylene composite material is close to that of Example 6.

[0300] The polypropylene composition for injection foaming is prepared according to step (6) of Example 1. The polypropylene injection foaming forming body is prepared according to step (7) of Example 1, and the polypropylene composition injection foaming forming body is obtained. Its weight, drop height, production time and injection pressure are measured, and the results are shown in Table 1.

[0301] Comparative Example 6

[0302] The polypropylene composition for injection foaming is prepared according to step (6) of Example 1. The polypropylene injection foaming forming body is prepared according to step (7) of Example 1, and the polypropylene composition injection foaming forming body is obtained. Its weight, drop height, production time and injection pressure are measured, and the results are shown in Table 1.

[0303] Comparative Example 7

[0304] The three-layer co-extrusion polypropylene sheet, the polypropylene fabric and the polypropylene composite material are prepared according to the method of Example 1. The thickness of the prepared polypropylene composite material is close to that of Example 1.

[0305] The polypropylene composition for injection foam molding was prepared according to the procedure of step (6) of Example 1. The polypropylene injection foam molded body was prepared according to the procedure of step (7) of Example 1, except that 17 pieces of square sheet material (prepositioned reinforcing sheet material) with a side length of 100 mm were hung in the left and right cavities of the mold, with a spacing of 1.1 mm, and the outermost two pieces were positioned outside the injection foam molded body after injection foam molding, to obtain a polypropylene composition injection foam molded body. The weight, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0306] Comparative Example 8

[0307] A three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite were prepared according to the method of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0308] The polypropylene composition for injection foam molding was prepared according to the procedure of step (6) of Example 1. The polypropylene injection foam molded body was prepared according to the procedure of step (7) of Example 1, except that 5 pieces of square glass fiber composite sheet material with a side length of 300 mm and a thickness of 1.7 mm purchased on the market were layered and hung in the left and right cavities of the mold, to obtain a polypropylene composition injection foam molded body. The weight, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0309] Comparative Example 9

[0310] A three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite were prepared according to the method of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0311] The polypropylene composition for injection foam molding was prepared according to the procedure of step (6) of Example 1. The polypropylene injection foam molded body was prepared according to the procedure of step (7) of Example 1, except that 1 piece of stainless steel sheet with a side length of 300 mm and a thickness of 2.5 mm purchased on the market was hung in the left and right cavities of the mold, to obtain a polypropylene composition injection foam molded body. The weight, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0312] Comparative Example 10

[0313] The polypropylene composition was prepared according to the procedure of step (6) of Example 1. A polypropylene composition injection molded body was obtained using a general injection molding process without hanging any sheet material inside the mold. The weight, drop height, production time, and injection pressure were measured, and the results are shown in Table 1.

[0314] Comparative Example 11

[0315] A three-layer co-extruded polypropylene sheet, polypropylene fabric and polypropylene composite were prepared according to the method of Example 1. The thickness of the prepared polypropylene composite was close to that of Example 1.

[0316] The polypropylene composition for injection foaming was prepared according to step (6) of Example 1. The polypropylene composite prepared in step (4) of Example 1 was used as the pre-reinforced sheet. Five square sheets with a side length of 100 mm were stacked and hung in the left and right cavities of the mold. A general injection molding process was used to obtain the injection-molded polypropylene composition. The weight, drop height, production time and injection pressure were measured, and the results are shown in Table 1.

[0317] Experimental Example

[0318] The polypropylene composites and injection-molded polypropylene foaming bodies obtained in the above examples and comparative examples were tested according to the following method, and the test results are shown in Table 1.

[0319] (1) Drop impact resistance: measured according to the test method specified in GB4857.5 Packaging Transportation Packaging Pieces Drop. The drop heights tested were 500 mm, 600 mm, 800 mm, 1000 mm, 1200 mm and 1500 mm, and the intervals were increased by 300 mm from 1500 mm.

[0320] Table 1

[0321]

[0322]

[0323] As can be seen from the results of Table 1, the polypropylene composite prepared according to the present application has good tensile properties and impact resistance, and also has good interlayer peeling strength at a relatively low heat pressing temperature. As can be seen from Examples 7 and 8, adjusting the ratio of injection-foaming base resin polypropylene compositions A and B has no significant effect on the performance of the final product. i

[0324] Compared with the injection-molded foaming body of Comparative Example 6 (which is not reinforced by any reinforcing sheet), the injection-molded foaming body prepared using the reinforcing sheet has significantly improved vertical drop resistance and processing performance (shorter molding time and lower molding pressure) under similar weight reduction conditions compared with the injection-molded foaming body prepared by the conventional injection-foaming process. As can be seen from Comparative Examples 10 and 11, using a polypropylene composite sheet to reinforce a general injection-molded body without foaming has no obvious effect; the drop resistance of Comparative Example 6 is significantly weakened due to the presence of a large number of internal bubbles. However, the injection-molded foaming body of the examples can improve the vertical drop resistance under the premise of significant weight reduction and improved processing performance due to the presence of the polypropylene composite sheet in the reinforcing structure.​

[0325] As can be seen from Comparative Examples 1-4, using only a single layer sheet structure, a single polymer component, or using a layer ratio outside the scope of the application will result in a decrease in the performance of the laminated polypropylene sheet or fabric, and thus a decrease in the physical properties and processing performance of the final injection molded foamed molded body. Comparative Example 5 verifies that a melting point not according to the gradient in the present application cannot achieve the effect of the invention.

[0326] As can be seen from Examples 9, 10 and Comparative Example 7, the distance between the polypropylene composite reinforced sheets has a significant effect on the final product, as the distance between the sheets decreases, i.e. the number of sheets in the molded body increases, the physical properties improve and the production efficiency decreases, and when the distance between the sheets is too short, the processing performance decreases and it is difficult to obtain a qualified injection molded foamed product.

[0327] As can be seen from Comparative Examples 8, 9, although the use of glass fiber, metal and other commonly used sheet reinforcing means in the industry can also improve the vertical drop resistance of the injection molded foamed molded body to the level of the examples, the weight of the product will exceed that of Comparative Example 6, Comparative Example 10 and Comparative Example 11, and the processing performance will also decrease significantly.

[0328] The above has described various embodiments of the present application, the above description is exemplary and is not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0329] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges and values should be interpreted as approximately between the stated values. For ranges of values, the endpoints of the ranges are included in the range, and the endpoints and individual points within the ranges are included in the range. The ranges and individual points within the ranges can be combined to form new ranges, which are also contemplated within the scope of the present disclosure.

Claims

1. A polypropylene injection-molded foamed body comprising a polypropylene injection-molded foam material and a pre-placed reinforcement sheet arranged in the polypropylene injection-molded foam material, wherein the pre-placed reinforcement sheet comprises a polypropylene composite material; The polypropylene composite material comprises a plurality of polypropylene sheet unit groups stacked in sequence; each polypropylene sheet unit group comprises at least one identical or different polypropylene sheet unit, each polypropylene sheet unit comprises a core layer A i and located in the core layer A i Outer layer B on both sides i , B' i , structure B i A i B' i The structure of the polypropylene composite material is, from bottom to top, the nth group... the ith group... the 2nd group, the 1st group, the 2nd group... the ith group... the nth group, and the total number of stacked polypropylene sheet unit groups is 2n-1; i and n are both integers not less than 2, and i≤n; in, Core layer A in polypropylene sheet unit i Containing polypropylene composition A i , outer layer B i With outer layer B' i The same or different, each corresponding to a polypropylene composition B i , polypropylene composition B' i , The polypropylene composition A i The melting point is greater than that of the polypropylene composition B i , the polypropylene composition B' i The average melting point of all outer layers in the i-th group is greater than or equal to the average melting point of all outer layers in the i-1-th group; The number of the pre-set reinforcement sheets is at least two; The pre-placed reinforcement sheets that are farthest apart are respectively located outside the two ends of the injection-molded foaming body; the distance between the pre-placed reinforcement sheets inside the polypropylene injection-molded foaming body is 1.5-20 mm.

2. The polypropylene injection foamed molded body according to claim 1, wherein: Polypropylene composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in melting points of each of the following is greater than or equal to 5°C; and / or, The difference between the average value of the melting points of all outer layers in the i-th group and the average value of the melting points of all outer layers in the i-1-th group is the same or different and is each 1-40°C.

3. The polypropylene injection foamed molded article according to claim 1, wherein: Polypropylene composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in melting points of each of the following is greater than or equal to 10°C; and / or, The difference between the average value of the melting points of all outer layers in the i-th group and the average value of the melting points of all outer layers in the i-1-th group is the same or different and is each 1-10°C.

4. The polypropylene injection foamed molded article according to claim 1, wherein: Polypropylene composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in melting points of each of the following is greater than or equal to 20°C; and / or, The difference between the average value of the melting points of all outer layers in the i-th group and the average value of the melting points of all outer layers in the i-1-th group, which are the same or different, is 1-5°C.

5. The polypropylene injection foamed molded article according to claim 1, wherein: 2≤n≤100; and / or, Each polypropylene sheet unit group independently comprises 1 to 10 identical or different polypropylene sheet units.

6. The polypropylene injection foamed article according to claim 1, wherein: 2≤n≤50; and / or, Each polypropylene sheet unit group independently comprises 1 to 5 identical or different polypropylene sheet units.

7. The polypropylene injection foamed article according to claim 1, wherein: Based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit is i The thickness accounts for 51%-89% of the total thickness.

8. The polypropylene injection foamed article according to claim 1, wherein: Based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit is i The thickness accounts for 71%-89% of the total thickness.

9. The polypropylene injection foamed article according to claim 1, wherein: Based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit is i The thickness accounts for 71%-80% of the total thickness.

10. The polypropylene injection foamed molded article according to claim 1, wherein: The polypropylene composition A i Including one or more of homopolymer polypropylene, random copolymer polypropylene and impact copolymer polypropylene; and / or, The polypropylene composition B i , polypropylene composition B' i Each comprises one or more of homopolymer polypropylene, random copolymer polypropylene and impact copolymer polypropylene.

11. The polypropylene injection foamed article according to claim 1, wherein: The polypropylene composition B i , polypropylene composition B' i Each comprises one or more of homopolymer polypropylene, random copolymer polypropylene and impact copolymer polypropylene; the polypropylene composition B i and / or polypropylene composition B' i Also contains thermal bonding enhancer i .

12. The polypropylene injection foamed article according to claim 1, wherein: Polypropylene composition A i Including homopolymer polypropylene i and impact copolymer polypropylene b i .

13. The polypropylene injection foamed article according to claim 1, wherein: The polypropylene composition B i , the polypropylene composition B' i Each comprising random copolymer polypropylene x i and thermal bonding enhancers i .

14. The polypropylene injection foamed article according to claim 1, wherein: Polypropylene composition A i Including homopolymer polypropylene i and impact copolymer polypropylene b i ; With the polypropylene composition A i Based on the total weight of i Including 50-99wt% homopolymer polypropylene a i , 1-50wt% impact copolymer polypropylene b i and / or, The polypropylene composition B i , the polypropylene composition B' i Each comprising random copolymer polypropylene x i and thermal bonding enhancers i ; The polypropylene composition B i , the polypropylene composition B' i Based on the total weight of each, the polypropylene composition B i , the polypropylene composition B' i Each comprising 70-99 wt% of random copolymer polypropylene x i , 1-30wt% thermal adhesion enhancer y i .

15. The polypropylene injection foamed article according to claim 1, characterized in that: Polypropylene composition A i Including homopolymer polypropylene i and impact copolymer polypropylene b i ; The polypropylene composition A i Including 70-90wt% homopolymer polypropylene a i , 10-30wt% impact copolymer polypropylene b i and / or, The polypropylene composition B i , the polypropylene composition B' i Each comprising random copolymer polypropylene x i and thermal bonding enhancers i ; The polypropylene composition B i , the polypropylene composition B' i Each comprising 80-90 wt% of random copolymerized polypropylene x i , 10-20wt% thermal adhesion enhancer i .

16. The polypropylene injection foamed article according to claim 12, characterized in that: The homopolymer polypropylene a i have: A melting point of 150-170°C; and / or The melt flow rate at 230°C and 2.16 kg load is 0.5-50 g / 10 min and / or The uniformity (mm) is not less than 96%.

17. The polypropylene injection foamed article according to claim 16, wherein: The homopolymer polypropylene a i have: A melting point of 160-170°C; and / or The melt flow rate at 230°C and a load of 2.16 kg is 1-20 g / 10 min.

18. The polypropylene injection foamed article according to claim 16, wherein: The homopolymer polypropylene a i have: The melt flow rate at 230°C and 2.16 kg load is 2.5-18 g / 10 min.

19. The polypropylene injection foamed article according to claim 12, wherein: The impact-resistant copolymer polypropylene b i have: The impact-resistant copolymer polypropylene b i The melting point is 150-170°C: and / or, The impact-resistant copolymer polypropylene b i The monomer copolymerized with propylene is ethylene or butene; and / or, The impact-resistant copolymer polypropylene b i The melt flow rate at 230°C and 2.16 kg load is 0.5-50 g / 10 min; and / or The impact-resistant copolymer polypropylene b i The cantilever beam impact strength is not less than 20KJ / m 2 .

20. The polypropylene injection foamed article according to claim 19, wherein: The impact-resistant copolymer polypropylene b i have: The impact-resistant copolymer polypropylene b i The monomer copolymerized with propylene is butene; and / or, The impact-resistant copolymer polypropylene b i The melt flow rate at 230°C and 2.16 kg load is 1-20 g / 10 min.

21. The polypropylene injection foamed article according to claim 19, wherein: The impact-resistant copolymer polypropylene b i have: The impact-resistant copolymer polypropylene b i The melt flow rate at 230°C and 2.16 kg load is 2.5-18 g / 10 min.

22. The polypropylene injection foamed article according to claim 13, wherein: The random copolymer polypropylene x i have: A melting point of 110-150°C; and / or The melt flow rate at 230°C and 2.16 kg load is 0.5-50 g / 10 min; and / or a molecular weight distribution Mw / Mn of 5-12; and / or, The random copolymer polypropylene x i It is a copolymer of propylene and ethylene and / or butene.

23. The polypropylene injection foamed article according to claim 22, characterized in that: The random copolymer polypropylene x i have: A melting point of 120-140°C; and / or A melt flow rate of 1-20 g / 10 min at 230° C. and 2.16 kg load; and / or a molecular weight distribution Mw / Mn of 7-10; and / or, The random copolymer polypropylene x i It is an ethylene-propylene-butene terpolymer and / or a propylene-ethylene binary copolymer.

24. The polypropylene injection foamed article according to claim 22, wherein: The random copolymer polypropylene x i have: The melt flow rate at 230°C and a load of 2.16 kg is 3-18 g / 10 min.

25. The polypropylene injection foamed article according to claim 13, wherein: The thermal bonding enhancer i have: The melting point or viscosity flow temperature is 70-110°C; and / or, The melt flow rate at 190°C and 2.16 kg load is 0.5-50 g / 10 min; and / or The thermal bonding enhancer i One or more selected from polyolefin elastomer, EPDM rubber, SEBS, SBS, EVA, and petroleum resin.

26. The polypropylene injection foamed article according to claim 25, characterized in that: The thermal bonding enhancer i have: A melt flow rate of 1-20 g / 10 min at 190° C. and 2.16 kg load; and / or The thermal bonding enhancer i It is a polyolefin elastomer and / or a petroleum resin.

27. The polypropylene injection foamed article according to claim 25, wherein: The thermal bonding enhancer i have: The melt flow rate at 190°C and a load of 2.16 kg is 1-18 g / 10 min.

28. The polypropylene injection foamed article according to claim 26, wherein: The thermal bonding enhancer i The polyolefin elastomer is a copolymer elastomer of ethylene, propylene and / or α-olefin.

29. The polypropylene injection foamed article according to claim 26, wherein: The thermal bonding enhancer i The polyolefin elastomer is a copolymer elastomer of ethylene and α-olefin.

30. The polypropylene injection foamed article according to claim 26, wherein: The thermal bonding enhancer i The polyolefin elastomer is a copolymerized elastomer of ethylene and α-olefin, and the α-olefin is a C4-C12 α-olefin.

31. The polypropylene injection foamed article according to claim 26, wherein: The thermal bonding enhancer i The polyolefin elastomer is a copolymer elastomer of ethylene and α-olefin, and the α-olefin is 1-butene and / or 1-octene.

32. The polypropylene injection foamed article according to claim 26, wherein: The thermal bonding enhancer i The petroleum resin is a C5 and / or C9 hydrogenated petroleum resin with a softening point of 100-150°C.

33. The polypropylene injection foamed article according to claim 32, wherein: The petroleum resin is a cyclopentadiene type resin.

34. The polypropylene injection foamed article according to claim 12, wherein: The core layer A i It also contains a β-crystal nucleating agent.

35. The polypropylene injection foamed article according to claim 34, characterized in that: The β-crystal nucleating agent is at least one selected from the group consisting of condensed ring aromatic hydrocarbons, Group IIA two-component complexes, aromatic diamides, rare earth compounds, and cyclic dicarboxylates; and / or, The polypropylene composition A i The total amount is 100 parts by weight, the core layer A i The content of the β crystal nucleating agent is 0.01-0.5 parts by weight.

36. The polypropylene injection foamed article according to any one of claims 1 to 35, characterized in that: The polypropylene sheet unit is a polypropylene sheet and / or a polypropylene fabric.

37. The polypropylene injection foamed article according to claim 36, wherein: The polypropylene sheet comprises a polypropylene composition A i , polypropylene composition B i , polypropylene composition B' i The components including the above are co-extruded to obtain the same.

38. The polypropylene injection foamed article according to claim 36, wherein: The polypropylene fabric is prepared by the following method: firstly i , polypropylene composition B i , polypropylene composition B' i The inner components are co-extruded to obtain a polypropylene sheet, and the polypropylene sheet is then woven to obtain the polypropylene fabric.

39. The polypropylene injection foamed article according to claim 38, wherein: The polypropylene fabric has a three-dimensional structure of plain, twill and / or satin.

40. The polypropylene injection foamed article according to claim 39, wherein: The polypropylene sheet units are connected by hot pressing and bonding.

41. The polypropylene injection-molded foamed article according to any one of claims 1 to 35, characterized in that: The polypropylene injection molding foam material contains the polypropylene composition A i At least one of and / or the polypropylene composition B i , polypropylene composition B' i At least one of, and an auxiliary agent.

42. The polypropylene injection-molded foamed article according to claim 41, wherein: The auxiliary agent is selected from one or more of antioxidants, antistatic agents, lubricants, anti-aging agents, and color powders.

43. The polypropylene injection-molded foamed article according to claim 41, wherein: The polypropylene injection molding foam material contains a chemical foaming agent and / or an organic physical foaming agent and / or is foamed by an inorganic physical foaming agent.

44. The polypropylene injection foamed article according to claim 43, wherein: The inorganic physical foaming agent is selected from at least one of air, nitrogen, carbon dioxide, oxygen and water.

45. The polypropylene injection-molded foamed article according to claim 43, wherein: The chemical foaming agent is selected from at least one of azodicarbonamide, p-toluenesulfonyl hydrazide, semicarbazides, tetrazoles, sodium bicarbonate and sodium citrate; the organic physical foaming agent is selected from at least one of aliphatic hydrocarbon foaming agents, alicyclic hydrocarbon foaming agents and halogenated hydrocarbon foaming agents.

46. ​​The polypropylene injection-molded foamed article according to any one of claims 1 to 35, characterized in that: The distance between the pre-set reinforcement sheets inside the polypropylene injection foamed molded body is 2-10 mm.

47. A method for preparing a polypropylene injection foaming molded article according to any one of claims 1 to 46, comprising the following steps: a. firstly melt-mixing a matrix raw material comprising the polypropylene injection molding foaming material to obtain a polypropylene composition for injection molding foaming; b. placing a pre-set reinforcement sheet in a mold, mixing the polypropylene composition for injection molding and foaming with a foaming agent, and performing injection molding and foaming in the mold to form a polypropylene injection molding foam material to obtain the polypropylene injection molding foam molded body.

48. Use of the polypropylene injection molded foam molded body according to any one of claims 1 to 46 or the polypropylene injection molded foam molded body prepared by the preparation method described in claim 47 in materials used in at least one of the following fields: automobiles, communications, aircraft, logistics, thermal insulation, precision machinery and electronic turnover, and packaging.

Images