Halogen-free flame-retardant low-warpage polypropylene lock catch floor base material and preparation method thereof

Abstract

The invention belongs to the technical field of floor base materials, and particularly relates to a halogen-free flame-retardant low-warpage polypropylene lock catch floor base material and a preparation method thereof. The polypropylene lock catch floor base material provided by the invention is mainly prepared by mixing and extruding calcium carbonate, polypropylene resin, lignin, a nucleating agent, a flexibilizer, a flame retardant, a lubricant and an antioxidant. According to the polypropylene lock catch floor base material, calcium carbonate serves as stone powder aggregate, polypropylene resin formed by compounding homo-polypropylene and co-polypropylene is adopted to replace traditional polyvinyl chloride resin, and lignin is further introduced to serve as a charring agent and a flame retardant synergist; the mechanical property, the dimensional stability and the flame retardant property of the polypropylene floor can be effectively improved. Compared with an existing plastic floor, the lock catch floor prepared from the floor base material has the advantages of being low in warping, not prone to cracking shrinkage, not prone to arching deformation, free of halogen and resistant to flame, and has extremely wide application potential in the field of preparation of high-quality lock catch floors.

Description

Technical Field

[0001] The invention belongs to the technical field of floor substrates, and in particular relates to a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate and a preparation method thereof. Background Art

[0002] The interlocking floor is a popular type of floor in recent years. It is connected by the interlocking tenons around the floor, and the floor is assembled into an integral structure without any laying conditions. The interlocking floor has the performance characteristics of both wood and plastic, and does not require the use of nails and glue during installation. It is highly environmentally friendly and easy to disassemble. Different patterns can also be designed according to the decorative effect to meet the needs of different occasions and tastes. It is deeply loved by consumers and has been widely used in home decoration, commercial offices, entertainment venues, etc.

[0003] The interlocking floor is usually composed of a floor substrate and an auxiliary functional layer. The floor substrate is the core component of the interlocking floor. It is a composite board made of stone powder and thermoplastic polymer materials that are mixed evenly and then extruded at high temperature. The performance of the floor substrate also determines the service life of the interlocking floor to a large extent.

[0004] At present, the most common indoor locking flooring on the market is the flooring with a polyvinyl chloride (PVC) substrate. PVC flooring is widely used in home or commercial places because of its advantages such as good flame retardancy, good dimensional stability, rich colors and patterns, and low price. However, the PVC molecular structure in the PVC floor substrate contains chlorine atoms, which will produce toxic gases such as hydrogen chloride and dioxins during the molding and combustion processes. Moreover, PVC floors usually require a large amount of plasticizers such as dioctyl terephthalate (DOTP) to be added, which has a great impact on the environment. With the rapid development of society, people have higher and higher environmental protection requirements for indoor flooring materials, which also limits the further application of PVC locking floors. In addition, after long-term use, locking floors will inevitably crack, warp, shrink, arch and deform.

[0005] Therefore, how to develop a new type of lock-in floor substrate to meet the development needs of lock-in floor for environmental protection, and at the same time comprehensively improve the defects of lock-in floor such as cracking, warping, shrinkage, arching and deformation, has become a technical problem that urgently needs to be solved. Summary of the invention

[0006] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate. The lock floor prepared from the substrate is not only green and environmentally friendly, but also has good dimensional stability and flame retardant properties, and can effectively improve the defects of the floor such as cracking, warping, shrinkage, arching and deformation, and meets the development requirements of the flooring field for high-quality lock floors.

[0007] The present invention also aims to provide a method for preparing the above-mentioned halogen-free, flame-retardant, low-warping polypropylene snap-fit ​​floor substrate.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A halogen-free flame-retardant low-warping polypropylene lock floor substrate is prepared by mixing and extruding the following raw materials in parts by weight: 200-400 parts of calcium carbonate, 80-120 parts of polypropylene resin, 10-30 parts of lignin, 0.2-2 parts of nucleating agent, 10-20 parts of toughening agent, 20-40 parts of flame retardant, 2-5 parts of lubricant, and 1-3 parts of antioxidant;

[0010] Wherein, the polypropylene resin is a blend of homopolypropylene and copolymer polypropylene; and the flame retardant is a blend of piperazine pyrophosphate and polysiloxane.

[0011] Furthermore, in order to improve the stability of the substrate, the melt index of the homopolypropylene is 1.7 to 2.7 g / 10 min; and the melt index of the copolymer polypropylene is 1.5 to 2.5 g / 10 min.

[0012] Furthermore, the mass ratio of homopolypropylene to copolymer polypropylene is 1:(0.8-1.2), more preferably 1:1.

[0013] Furthermore, the nucleating agent is one or more of 2,2′-methylene-bis(4,6-tert-butylphenol)phosphine aluminum salt, dibenzylidene sorbitol, sodium benzoate, talc, and carbon black.

[0014] Furthermore, the toughening agent is one or more of ethylene propylene diene monomer rubber (EPDM), styrene-butadiene-styrene block copolymer (SBS), polyolefin elastomer (POE), and ethylene-vinyl acetate copolymer (EVA).

[0015] Furthermore, the polysiloxane is one or more of hydroxyphenyl ladder silsesquioxane, phenyl silsesquioxane, and ladder silsesquioxane.

[0016] Furthermore, the particle size of the lignin is 100-400 meshes; the particle size of the calcium carbonate is 400-800 meshes.

[0017] Furthermore, the lubricant is one or more of polyethylene wax, polypropylene wax, montan wax, and zinc stearate; the antioxidant is one or more of hindered phenols, aromatic amines, phosphites, and sulfur-containing esters.

[0018] The preparation method of the above-mentioned halogen-free flame-retardant low-warping polypropylene lock floor substrate comprises the following steps:

[0019] (1) mixing calcium carbonate, polypropylene resin, lignin, nucleating agent, toughening agent, flame retardant, lubricant and antioxidant according to the mass fraction of raw materials, and then mixing at a temperature of 100 to 150° C. to obtain a base material mixture;

[0020] (2) Extruding the substrate mixture to obtain a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate.

[0021] Furthermore, the mixing time is 10 to 20 minutes.

[0022] Further, the extrusion molding process is as follows: the temperature of zone 1 of the mold is 172-177°C, the temperature of zone 2 is 175-182°C, the temperature of zone 3 is 180-190°C, the temperature of zone 4 is 175-182°C, and the temperature of zone 5 is 172-177°C; the temperature of zone 1 of the extruder barrel is 170-175°C, the temperature of zone 2 is 165-170°C, the temperature of zone 3 is 158-160°C, the temperature of zone 4 is 150-155°C, the temperature of zone 5 is 148-153°C, and the temperature of zone 6 is 145-150°C; the main engine current is 205-215A; the feeding speed is 280-400kg / h; the main engine speed is 300-350rpm; the extrusion pressure is 3-6MPa; and the extrusion speed is 100-140kg / h.

[0023] The advantages and beneficial effects of the technical solution of the present invention are:

[0024] The polypropylene lock floor substrate provided by the invention is mainly prepared by mixing calcium carbonate, polypropylene resin, lignin, a nucleating agent, a toughening agent, a flame retardant, a lubricant and an antioxidant and then extruding the mixture.

[0025] Among them, the floor substrate provided by the present invention uses calcium carbonate as stone powder aggregate, and uses a polypropylene resin compounded from homopolypropylene (homoPP) and copolymer polypropylene (coPP) to replace traditional polyvinyl chloride resin. The present invention uses a mixture of copolymer PP and homoPP to promote the balance of material rigidity and toughness and reduce costs. Lignin is further introduced as a carbonizing agent and flame retardant synergist. Lignin can form a fiber structure in the material to prevent the material from deforming and cracking. In addition, the benzene ring skeleton in the lignin structure enables it to produce a higher amount of residual carbon during the combustion process, and the rich hydroxyl groups promote the carbonization reaction, improve the thermal stability and carbonization of the material, thereby effectively improving the mechanical properties, dimensional stability and flame retardant properties of the polypropylene floor.

[0026] Compared with existing plastic floors, the lock-in floor prepared from the floor substrate of the present invention has the advantages of low warping, not easy to crack and shrink, not easy to arch and deform, and halogen-free flame retardant. It has extremely broad development prospects and huge application potential in the field of high-quality lock-in floor preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of a snap-in floor product prepared from the halogen-free, flame-retardant, low-warping polypropylene snap-in floor substrate of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, features and advantages of the above technical solution of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail in combination with specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from this description, and those skilled in the art can make equivalent substitutions without violating the connotation of the present invention, so the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the raw materials used are all commonly used in the art, available to the public or commercially available, unless otherwise specified.

[0030] In the following embodiments of the present invention, a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate is provided, which is prepared by mixing and extruding the following raw materials in parts by weight: 200-400 parts of calcium carbonate, 80-120 parts of polypropylene resin, 10-30 parts of lignin, 0.2-2 parts of nucleating agent, 10-20 parts of toughening agent, 20-40 parts of flame retardant, 2-5 parts of lubricant, and 1-3 parts of antioxidant; wherein the polypropylene resin is a blend of homopolypropylene and copolymer polypropylene; and the flame retardant is a blend of piperazine pyrophosphate and polysiloxane.

[0031] Furthermore, the melt index of homopolypropylene is 1.7-2.7 g / 10 min; the melt index of copolymer polypropylene is 1.5-2.5 g / 10 min. The melt indexes of homopolypropylene and copolymer polypropylene used in the following examples meet the above requirements and are specifically from Kingfa Science & Technology Co., Ltd.

[0032] Furthermore, the mass ratio of homopolypropylene to copolymer polypropylene is 1:(0.8-1.2), more preferably 1:1.

[0033] Further, the nucleating agent is one or more of 2,2′-methylene-bis(4,6-tert-butylphenol)phosphine aluminum salt (hereinafter referred to as NA-21), dibenzylidene sorbitol, sodium benzoate, talc, and carbon black. Specifically, the nucleating agent used in the following examples is NA-21, which comes from Shanghai Qirun New Materials Co., Ltd.

[0034] Further, the toughening agent is one or more of EPDM rubber, styrene-butadiene-styrene block copolymer, polyolefin elastomer, and ethylene-vinyl acetate copolymer. Specifically, the toughening agent used in the following examples is EPDM rubber from Dow Chemical.

[0035] Further, the polysiloxane is one or more of hydroxyphenyl ladder silsesquioxane, phenyl silsesquioxane, and ladder silsesquioxane. Specifically, the hydroxyphenyl ladder silsesquioxane used in the following examples is SIFR-SI907, the phenyl silsesquioxane is SIFR-SI908, and the ladder silsesquioxane is SIFR-770N, all of which are from Quansheng Polycarbon Technology Co., Ltd.

[0036] Furthermore, the particle size of lignin is 100-400 meshes, and the particle size of calcium carbonate is 400-800 meshes. Specifically, the lignin used in the following examples comes from Wuhan Jiyesheng Chemical Co., Ltd.

[0037] Further, the lubricant is one or more of polyethylene wax, polypropylene wax, montan wax, and zinc stearate; the antioxidant is one or more of hindered phenols, aromatic amines, phosphites, and sulfur-containing esters. Specifically, the lubricant used in the following examples is polyethylene wax, which comes from Xingbeida Chemical Materials Co., Ltd. The antioxidant used in the following examples is antioxidant 1010, which comes from Tianjin Lianlong New Materials Co., Ltd.

[0038] Example 1

[0039] This embodiment provides a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate, which is prepared by mixing and extruding the following raw materials in parts by weight: 300 parts of calcium carbonate, 100 parts of polypropylene resin, 15 parts of lignin, 1 part of nucleating agent, 15 parts of toughening agent, 25 parts of flame retardant, 3 parts of lubricant, and 2 parts of antioxidant.

[0040] The polypropylene resin is a blend of homopolymer polypropylene and copolymer polypropylene in a mass ratio of 1:1. The nucleating agent is 2,2′-methylene-bis(4,6-tert-butylphenol)phosphine aluminum salt (NA-21). The toughening agent is ethylene propylene diene rubber (model 722P). The flame retardant is composed of 20 parts of piperazine pyrophosphate and 5 parts of polysiloxane. The polysiloxane is specifically hydroxyphenyl ladder silsesquioxane (model SIFR-SI907). The lubricant is polyethylene wax. The antioxidant is antioxidant 1010. The particle size of lignin is 100 to 400 mesh. The particle size of calcium carbonate is 400 to 800 mesh.

[0041] This embodiment provides a method for preparing the above-mentioned halogen-free flame-retardant low-warping polypropylene lock floor substrate, comprising the following steps:

[0042] S1. Mix the above raw materials according to the mass fractions, and then place them in a high-speed mixer for mixing. The mixing temperature is 120° C. and the mixing time is 15 min to obtain a PP base material mixture;

[0043] S2. The PP base material mixture is placed in an extruder for extrusion molding to obtain a halogen-free, flame-retardant, low-warping polypropylene lock floor base material.

[0044] This embodiment also provides a polypropylene lock floor, and its cross-sectional schematic diagram is as follows Figure 1 As shown, from top to bottom, it includes: PP transparent film, PP color film, PP substrate, IXPP mute pad. Among them, the PP substrate is the halogen-free flame-retardant low-warping polypropylene lock floor substrate prepared in Example 1 of the present invention. The preparation method of the polypropylene lock floor of this embodiment includes the following steps:

[0045] A PP colored film and a PP transparent film are firstly adhered on the halogen-free flame-retardant and low-warping polypropylene lock floor substrate prepared as above; then an electron radiation cross-linked polypropylene (IXPP) silent pad is adhered under the lock floor substrate, and laminated at a temperature of 35°C and a pressure of 10MPa. After the lamination, the laminate is placed in a constant temperature chamber of 32°C for curing for 2 hours to obtain a polypropylene floor; the obtained polypropylene floor is further subjected to an unlocking treatment to obtain a polypropylene lock floor.

[0046] In this embodiment, when preparing the polypropylene lock floor substrate, the extrusion molding equipment used is a twin-screw extruder with a diameter of 110 mm. The temperature, pressure, time and other parameters of the extrusion molding process have an important influence on the final quality of the floor material. Different extrusion process parameters may cause defects such as warping, cracks, and insufficient strength of the material.

[0047] Based on this, in this embodiment, the above-mentioned PP base material mixture is placed in an extruder for extrusion molding. The optimal extrusion molding process obtained by experimental optimization is: the temperature of the first zone of the extruder mold is 172-177°C, the temperature of the second zone is 175-182°C, the temperature of the third zone is 180-190°C, the temperature of the fourth zone is 175-182°C, and the temperature of the fifth zone is 172-177°C. The temperature of the first zone of the extruder barrel is 170-175°C, the temperature of the second zone is 165-170°C, the temperature of the third zone is 158-160°C, the temperature of the fourth zone is 150-155°C, the temperature of the fifth zone is 148-153°C, and the temperature of the sixth zone is 145-150°C. The main machine current is 205-215A. The feeding speed is 280-400kg / h. The main machine speed is 300-350rpm. The extrusion pressure is 3-6MPa. The extrusion speed is 100-140kg / h.

[0048] In order to improve the efficiency of the extrusion molding process and obtain the best product performance, the following intelligent control system is used to control the extrusion molding process under the above-mentioned optimal process conditions. The specific control method includes the following steps S1 to S5:

[0049] S1. During the extrusion process, install temperature sensors, pressure sensors, current sensors, and speed sensors to collect the extruder barrel temperature, mold temperature, extrusion pressure, host current, and host speed of the extruder in real time, and perform data preprocessing, including noise removal and normalized data. It is understandable that the pressure control is adjusted by the host current. Under the same host screw speed conditions, the faster the speed and the higher the host current, the greater the relative pressure and the better the plasticization.

[0050] Specifically, Kalman filtering or mean filtering is used to denoise the data, and the data of each sensor is normalized to the range of [0, 1].

[0051] Specifically, the temperature control range of the extruder barrel is: zone 1 temperature 170-175°C, zone 2 temperature 165-170°C, zone 3 temperature 158-160°C, zone 4 temperature 150-155°C, zone 5 temperature 148-153°C, zone 6 temperature 145-150°C. The temperature control range of the extruder die is: zone 1 temperature 172-177°C, zone 2 temperature 175-182°C, zone 3 temperature 180-190°C, zone 4 temperature 175-182°C, zone 5 temperature 172-177°C. The extrusion pressure is 3-6MPa. The host current is 205-215A. The host speed is 300-350rpm.

[0052] S12. According to the raw material formula and target performance, set the target value and threshold of the extrusion pressure during the extrusion process to ensure that the pressure is controlled within a reasonable range and the density and surface smoothness of the finished product are guaranteed. At the same time, set the range of the extrusion speed to ensure uniform thickness and prevent warping or cracking.

[0053] Specifically, the extrusion pressure is 3 to 6 MPa and the extrusion speed is 100 to 140 kg / h.

[0054] Specifically, according to the characteristics of the material, select a suitable target pressure value, and then set the target extrusion speed according to the stable operating conditions of the extruder and the flow characteristics of the material. According to the target parameter value and process tolerance, set the upper and lower limit thresholds of the extrusion pressure value and the extrusion speed, including the pressure threshold and the extrusion speed threshold, to ensure the stability of the extrusion process.

[0055] S13, the fuzzy control algorithm compares the real-time collected sensor data (such as extrusion pressure, extrusion speed) with the set target value to generate a control signal. The fuzzy controller adjusts the extrusion pressure and extrusion speed of the extruder according to fuzzy rules (for example, "if the pressure is high, reduce the extrusion speed") to ensure that these parameters remain within the preset range.

[0056] Specifically, according to the set extrusion pressure and extrusion speed target values ​​and the real-time collected extrusion pressure and extrusion speed data, the current error value and error change rate are calculated, and the error value includes the extrusion pressure error and the extrusion speed error. Subsequently, the error value and the error change rate are fuzzified and converted into fuzzy language variables, such as high, medium, and low, and the fuzzification is completed through the membership function. After that, according to the fuzzy rules (such as "if the extrusion pressure error is high, increase the extrusion speed"), reasoning is performed to calculate the fuzzy control output, and finally the calculated fuzzy control signal is converted into an actual adjustment signal for subsequent PID controller use.

[0057] Among them, the fuzzy membership function expression is:

[0058]

[0059] Where μ(eN) is the membership function, N max It is the maximum value of the physical quantity threshold. When it is the maximum pressure threshold, N can be replaced by P. If it is the maximum speed threshold, N can be replaced by V.

[0060] It is not difficult to understand that the fuzzy rules are consistent with the theory of process control in actual production. Usually, if the barrel temperature is too high (higher than the target value +2%), the mold temperature is lowered; if the mold temperature is too low (lower than the target value -2%), the barrel temperature in the corresponding area is increased. In addition, the feeding speed is proportional to the main machine current. The faster the speed, the greater the extrusion pressure: if the extrusion pressure is high (higher than 6MPa), the feeding speed is reduced; if the extrusion pressure is low (lower than 3MPa), the screw speed is increased. For the cycle, if the cycle is too long (greater than 120 seconds), the feeding speed and main machine speed are increased; if the cycle is too short (less than 60 seconds), the main machine speed is appropriately reduced.

[0061] S14, PID controller further fine-tunes the extrusion pressure and extrusion speed of the extruder according to the adjustment signal output by the fuzzy controller. PID control eliminates real-time errors through three control methods: proportional, integral, and differential, and keeps the pressure and speed within the optimal range to accurately adjust each parameter in the extrusion process, thereby ensuring the uniform thickness and smooth surface of the floor substrate and avoiding quality problems caused by control fluctuations.

[0062] Specifically, the error value of the PID controller is calculated based on the adjustment signal output by the fuzzy controller, and then the proportional, integral and differential terms of the PID controller are calculated based on the error value. Subsequently, the results of the proportional, integral and differential terms are calculated comprehensively to obtain the adjustment signal of the PID controller. Finally, the calculated PID controller adjustment signal is transmitted to the control system to adjust the pressure and speed of the extruder.

[0063] Among them, the PID signal output expression is:

[0064] u N =N output +I N +D N

[0065] In the formula, u N is the regulation output signal of the PID controller, N output is the proportional term, I N is the integral term, D N is the differential term, N refers to the physical quantity, which is the same as above and will not be repeated here.

[0066] S15. The real-time monitoring system tracks various parameters during the extrusion process. When the actual data is detected to deviate from the set target, the system will automatically feedback the adjustment signal and adjust the extrusion pressure and extrusion speed in real time to ensure that the equipment is always within the optimal process range.

[0067] Specifically, the real-time monitoring system continuously collects key data such as pressure, speed, humidity, etc. through sensors, and transmits the data to the control system for analysis. The error between the real-time collected data and the set value of the PID controller is calculated, and the control parameters are adjusted according to the error. The adjusted control parameters are transmitted to the PID controller for one-step adjustment.

[0068] Example 2

[0069] This embodiment provides a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that the flame retardant used in this embodiment is composed of 22.5 parts of piperazine pyrophosphate and 2.5 parts of polysiloxane; the remaining processes and parameters are the same as those of Example 1.

[0070] This embodiment also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the halogen-free, flame-retardant, low-warping polypropylene lock floor substrate of Example 2 is used to prepare the polypropylene lock floor.

[0071] Example 3

[0072] This embodiment provides a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate, whose composition and overall preparation method are basically the same as those in Example 1, except that the flame retardant used in this embodiment consists of 20 parts of piperazine pyrophosphate and 5 parts of polysiloxane; the polysiloxane is specifically phenyl silsesquioxane (model SIFR-SI908), and the rest of the process is the same as in Example 1.

[0073] This embodiment also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the halogen-free, flame-retardant, low-warping polypropylene lock floor substrate of Example 3 is used to prepare the polypropylene lock floor.

[0074] Example 4

[0075] This embodiment provides a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that the flame retardant used in this embodiment consists of 20 parts of piperazine pyrophosphate and 5 parts of polysiloxane; the polysiloxane is specifically trapezoidal silsesquioxane (model SIFR-770N), and the rest of the process is the same as that of Example 1.

[0076] This embodiment also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the halogen-free, flame-retardant, low-warping polypropylene lock floor substrate of Example 4 is used to prepare the polypropylene lock floor.

[0077] Comparative Example 1

[0078] This comparative example provides a polypropylene locking floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that: the raw materials used in this comparative example omit both flame retardant and lignin, and other conditions and parameters are the same as those of Example 1.

[0079] This comparative example also provides a polypropylene lock floor, and its overall preparation method is basically the same as that of Example 1, except that the polypropylene lock floor substrate of Comparative Example 1 is used to prepare the polypropylene lock floor.

[0080] Comparative Example 2

[0081] This comparative example provides a polypropylene locking floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that lignin is omitted from the raw materials used in this comparative example, and other conditions and parameters are the same as those of Example 1.

[0082] This comparative example also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the polypropylene lock floor substrate of Comparative Example 2 is used to prepare the polypropylene lock floor.

[0083] Comparative Example 3

[0084] This comparative example provides a polypropylene locking floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that the flame retardant is omitted from the raw materials used in this comparative example, and other conditions and parameters are the same as those of Example 1.

[0085] This comparative example also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the polypropylene lock floor substrate of Comparative Example 3 is used to prepare the polypropylene lock floor.

[0086] Comparative Example 4

[0087] This comparative example provides a polypropylene lock floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that: this comparative example uses 100 parts of homopolypropylene to replace the homopolypropylene and copolymer polypropylene blend in Example 1, and other conditions and parameters are the same as those in Example 1.

[0088] This comparative example also provides a polypropylene lock floor, and its preparation method is basically the same as that of Example 1, except that the polypropylene lock floor substrate of Comparative Example 4 is used to prepare the polypropylene lock floor.

[0089] Comparative Example 5

[0090] This comparative example provides a polypropylene lock floor substrate, whose composition and overall preparation method are basically the same as those of Example 1, except that: this comparative example uses 100 parts of copolymerized polypropylene to replace the homopolymerized polypropylene and the copolymerized polypropylene blend in Example 1, and other conditions and parameters are the same as those in Example 1.

[0091] This comparative example also provides a polypropylene lock floor, and its overall preparation method is basically the same as that of Example 1, except that the polypropylene lock floor substrate of Comparative Example 5 is used to prepare the polypropylene lock floor.

[0092] Test example: Performance test of locking floor

[0093] This test example tests the performance of the polypropylene lock flooring prepared in Examples 1 to 4 of the present invention and Comparative Examples 1 to 5.

[0094] Among them, the warpage performance: tested according to ISO24342 standard: the sample is cut into a 250mm×250mm square, placed on a flat table, and the four corners of the sample are tested one by one with a feeler gauge. The test result selects the maximum value among the four corners.

[0095] Heat shrinkage test: Test according to ISO24342 standard: Cut the sample into a 250mm×250mm square, measure the length and width of the sample (all four sides need to be measured and recorded, length is L10, L20, width is W10, W20), place the sample in an 80℃ oven, take it out after 6 hours and place it in the laboratory for 3 hours, and then test the length and width of the sample (length is L11, L21, width is W11, W21). Calculate according to the following formula: length: {[(L10+L20) / 2-(L11+L21) / 2] / [(L10+L20) / 2]}×100%; width: {[(W10+W20) / 2-(W11+W21) / 2] / [(W10+W20) / 2]}×100%, and select the maximum value for the test result.

[0096] Thermal expansion test: Cut a 180mm×1220mm sample, place it in a drying room, and set the drying room temperature to 20℃. After the drying room reaches the set temperature, keep it warm for 3h, measure the length and width, and record the length as L10 and L20, and the width as W10 and W20. Then set the drying room temperature to 70℃, keep it warm for 3h after reaching the set temperature, measure the length and width, and record the length as L11 and L21, and the width as W11 and W21. Calculate the experimental data, the thermal expansion coefficient of length is: {[(L11+L21) / 2-(L10+L20) / 2] / [(L10+L20) / 2] / 50}×100000; the thermal expansion coefficient of width is: {[(W11+W21) / 2-(W10+W20) / 2] / [(W10+W20) / 2] / 50}×100000, and the maximum value is selected for the test result.

[0097] Low temperature drop ball test: Tested in accordance with EN13329 standard. Take a 300mm×250mm sample and place it on the chassis of the drop ball impact tester, fix it with screws, and use a 2280g ball to drop from a height of 1500mm for impact test.

[0098] Lighting test: Cut a 180mm×1220mm sample, place it in a lighting laboratory, set the lighting temperature to 70℃, and light for 3 hours.

[0099] Elastic modulus and static bending strength test: Test according to GB / T17657-2013 standard. Cut 50mm×150mm samples, measure the sample thickness, place the samples on the support roller of the universal mechanical testing machine, input the sample thickness and then test.

[0100] Flame retardant performance: Tested in accordance with GB / T11785-2005 standard. Cut a 1050mm×230mm sample, first fix the calibration plate on the combustion test instrument platform for heat flux calibration, and after the calibration is completed, remove the calibration plate and replace the test plate. Ignite the ignition source torch, and after 120s, the ignition source torch moves forward to ignite the sample, and after 720s, the ignition source torch goes out and retreats. After the combustion flame goes out, the combustion test instrument automatically records the position and calculates the radiation flux.

[0101] The performance test results of the polypropylene lock floor panels of Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 1.

[0102] Table 1 Performance test data of polypropylene lock flooring of Examples 1 to 4 and Comparative Examples 1 to 5

[0103]

[0104]

[0105] As shown in Table 1, the lock floor prepared by the polypropylene substrate layer of Examples 1 to 4 of the present invention has a warpage of ≤0.98 mm, a thermal shrinkage of ≤0.09%, and a thermal expansion coefficient of ≤6.0×10 -5 , no cracking in falling ball impact, no arching in illumination test, elastic modulus ≥ 2200MPa, static bending strength ≥ 18MPa, radiation flux ≥ 8.2kW / m 2 The comprehensive performance indicators are better than those of the lock-in floors prepared with the substrate layers of Comparative Examples 1 to 5.

[0106] Based on the above results, it can be known that the polypropylene lock floor substrate provided by the present invention is mainly prepared by mixing calcium carbonate, polypropylene resin, lignin, nucleating agent, toughening agent, flame retardant, lubricant, and antioxidant and then extruding. Among them, the floor substrate provided by the present invention uses calcium carbonate as stone powder aggregate, and uses polypropylene resin compounded with homopolymer polypropylene and copolymer polypropylene to replace traditional polyvinyl chloride resin, and further introduces lignin as a carbonizing agent and flame retardant synergist, which can effectively improve the mechanical properties, dimensional stability and flame retardant properties of polypropylene floor. Compared with the existing plastic floor, the lock floor prepared by the floor substrate of the present invention has the advantages of low warping, not easy to crack and shrink, not easy to arch and deform, and halogen-free flame retardant, and has extremely broad development prospects and huge application potential in the field of high-quality lock floor preparation.

[0107] It should be noted that although the above embodiments describe the technical solutions of the present invention in detail, these embodiments are only illustrative examples rather than restrictive definitions. Those skilled in the art should understand that any modification or equivalent substitution made without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention. Therefore, the protection scope of the present invention shall be based on the content defined in the claims.

Claims

1. A halogen-free, flame-retardant, low-warping polypropylene lock floor substrate, characterized in that: The material is prepared by mixing and extruding the following raw materials in parts by weight: 200-400 parts of calcium carbonate, 80-120 parts of polypropylene resin, 10-30 parts of lignin, 0.2-2 parts of nucleating agent, 10-20 parts of toughening agent, 20-40 parts of flame retardant, 2-5 parts of lubricant, and 1-3 parts of antioxidant; Wherein, the polypropylene resin is a blend of homopolypropylene and copolymer polypropylene; and the flame retardant is a blend of piperazine pyrophosphate and polysiloxane.

2. The halogen-free flame-retardant low-warping polypropylene snap-on floor substrate according to claim 1, characterized in that: The melting index of the homopolypropylene is 1.7-2.7 g / 10 min; the melting index of the copolymer polypropylene is 1.5-2.5 g / 10 min.

3. The halogen-free flame-retardant low-warping polypropylene lock floor substrate according to claim 1, characterized in that: The mass ratio of homopolymer polypropylene to copolymer polypropylene is 1:(0.8~1.2).

4. The halogen-free flame-retardant low-warping polypropylene lock floor substrate according to any one of claims 1 to 3, characterized in that: The nucleating agent is one or more of 2,2′-methylene-bis(4,6-tert-butylphenol)phosphine aluminum salt, dibenzylidene sorbitol, sodium benzoate, talc and carbon black.

5. The halogen-free flame-retardant low-warping polypropylene snap-on floor substrate according to any one of claims 1 to 3, characterized in that: The toughening agent is one or more of ethylene propylene diene monomer rubber, styrene-butadiene-styrene block copolymer, polyolefin elastomer, and ethylene-vinyl acetate copolymer.

6. The halogen-free flame-retardant low-warping polypropylene snap-on floor substrate according to any one of claims 1 to 3, characterized in that: The polysiloxane is one or more of hydroxyphenyl ladder silsesquioxane, phenyl silsesquioxane, and ladder silsesquioxane.

7. The halogen-free flame-retardant low-warping polypropylene snap-on floor substrate according to any one of claims 1 to 3, characterized in that: The particle size of the lignin is 100-400 meshes; the particle size of the calcium carbonate is 400-800 meshes.

8. The halogen-free, flame-retardant, low-warping polypropylene snap-on floor substrate according to any one of claims 1 to 3, characterized in that: The lubricant is one or more of polyethylene wax, polypropylene wax, montan wax and zinc stearate; the antioxidant is one or more of hindered phenols, aromatic amines, phosphites and sulfur-containing esters.

9. A method for preparing a halogen-free, flame-retardant, low-warping polypropylene snap-fit ​​floor substrate according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Calcium carbonate, polypropylene resin, lignin, nucleating agent, toughening agent, flame retardant, lubricant and antioxidant are mixed according to the weight proportion of raw materials, and then mixed at a temperature of 100-150° C. to obtain a base material mixture; (2) Extruding the substrate mixture to obtain a halogen-free, flame-retardant, low-warping polypropylene lock floor substrate.

10. The method for preparing the halogen-free flame-retardant low-warping polypropylene snap-fit ​​floor substrate according to claim 9, characterized in that: The mixing time is 10-20 min; the extrusion molding process is as follows: the temperature of the first zone of the mold is 172-177° C., the temperature of the second zone is 175-182° C., the temperature of the third zone is 180-190° C., the temperature of the fourth zone is 175-182° C., and the temperature of the fifth zone is 172-177° C.; the temperature of the first zone of the extruder barrel is 170-175° C., the temperature of the second zone is 165-170° C., the temperature of the third zone is 158-160° C., the temperature of the fourth zone is 150-155° C., the temperature of the fifth zone is 148-153° C., and the temperature of the sixth zone is 145-150° C.; the main machine current is 205-215A; the feeding speed is 280-400kg / h; the main machine speed is 300-350rpm; the extrusion pressure is 3-6MPa; and the extrusion speed is 100-140kg / h.

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