CN117903525A - Preparation method of recycled polypropylene composite material based on waste nylon carpet recycling byproducts - Google Patents

Abstract

The invention discloses a preparation method of a recycled polypropylene composite material based on waste nylon carpets and recycled byproducts. Firstly, after sorting, multi-channel crushing, pulping and centrifugal separation, the waste nylon carpet is subjected to high-purity polypropylene fluff byproducts, and secondly, the fluff-shaped polypropylene byproducts are changed into granular regenerated polypropylene through densification procedures, and the granular regenerated polypropylene raw material is subjected to blending modification with glass fibers, auxiliary agents and the like, extrusion processing, and finally the regenerated polypropylene modified composite material is prepared. This recycled composite has many advantages: (1) The by-product is used as the main raw material, thereby changing waste into valuable and having obvious cost advantage. (2) The composite material adopts the PCR resin, and accords with the current economic development concept of low carbon and environmental protection and sustainable resources. (3) The performance aspect can meet the material use requirements of most industries.

Description

Preparation method of recycled polypropylene composite material based on waste nylon carpet recycling byproducts

Technical Field

The patent relates to the redevelopment of waste nylon carpet recycled by-product polypropylene, in particular to the development and application of a regenerated polypropylene modified composite material.

Background

Carpets are textiles in which the surface layer fibers are disposed on the underlying fiber cloth in a bonded, woven or tufted manner. It is mainly composed of surface layer fiber, back lining and hard glue layer. Wherein, the backing material is mainly polypropylene, the hard glue layer is generally composed of a mixture of calcium carbonate, latex and the like, and the surface layer fiber is mainly prepared by melt spinning chemical fibers such as nylon (PA 6/PA 66), polypropylene (PP) or Polyester (PET) and the like. The nylon fiber has the characteristics of high strength, good wear resistance, antibiosis, mildew resistance, high color fastness and the like, is a polymer material with the largest usage amount in chemical fiber carpets at present, and occupies about 70% of market share of the carpet fiber.

Under this tremendous market share, a huge nylon carpet recycling market is derived. In order to recycle the waste nylon carpets, thereby digging out more circular economic benefits of the product, a series of recycling process flows are designed by many institutions.

CN 103949463A describes a waste carpet recycling method with low cost and convenient processing, which comprises physical treatment procedures of sorting, classifying, rolling, stripping and the like, and finally surface layer fiber and backing cloth are obtained, and the recycled materials are used in the building field and play roles of supporting and protecting.

CN 101838864A describes a method for recovering surface fibers of a carpet, which comprises grinding polypropylene back lining, hard glue layer and the like into fine powder state through a grinding wheel grinding device, and then passing through a multi-layer screen filtering device to realize mutual separation of powder and surface fibers, thus finally obtaining the surface fiber raw material with circular economic value.

CN 101631911B describes a method for recovering solvent-dissolved waste carpeting. Firstly, breaking carpet into a large number of tiny fragments, then, fully mixing a solvent system containing terpenes with the fragments to dissolve a part of carpet polymer in the solvent system, and after obtaining a terpene solvent mixed solution in which a part of polymer is dissolved, pumping out terpenes from the mixed solution to finally obtain the recovered polymer composition.

In these patents, researchers have focused on the recovery of high-performance surface layer fibers from waste nylon carpets with little attention to the byproducts generated during the recovery process. In actual production, the byproducts are usually buried or burned as garbage, which adds a lot of trouble to the ecological environment and enterprise operation.

This patent aims to exploit the regenerative economic value of these by-products. Firstly, a set of proprietary waste nylon carpet recycling equipment (US 7784719 B1 and US 67552336 B1) is adopted, a mature technological process is added, high-purity polypropylene byproducts are finely selected and separated, and secondly, a polypropylene modified composite material with excellent performance and stable product is obtained through a customized formula system and a stable extrusion process. Based on the automobile industry, the materials are popularized and applied to automobile parts, such as mechanical bearing products and non-appearance products, such as instrument supports, carbon tubes, bottom guard plates and the like. The production mode of changing waste into valuable and recycling is environment-friendly, the carbon footprint of the whole vehicle is effectively reduced, the material cost is greatly reduced, and a blood path is killed in strong market competition, so that more material selection schemes are provided for customers.

Disclosure of Invention

The invention aims to excavate the value of the byproduct polypropylene in the recovery process of the waste nylon carpet, finely separate out the high-purity polypropylene byproduct by a set of waste nylon carpet recovery equipment and a technological process, and further modify the raw material by glass fiber to finally obtain the polypropylene modified composite material with stable performance. The material has strong cost advantage and potential application value in products such as carbon tanks, mud guards and the like of automobile plastic parts.

The preparation of the regenerated polypropylene composite material mainly comprises the following three production links

(1) The main aim of the fine sorting and separation of the waste carpets is to separate the by-product polypropylene from the composition system of the waste nylon carpets to obtain high-purity polypropylene fluff

(2) The densification treatment of the polypropylene fluff mainly comprises the steps of processing the polypropylene fluff into polymer particles, facilitating the subsequent extrusion production and accurate feeding

(3) Blending, modifying and processing of regenerated polypropylene material

(4) The production flow chart of the regenerated polypropylene composite material is shown in figure 1

The first fine sorting and separating link mainly comprises the following specific steps:

First: fine picking process

The fine sorting procedure utilizes a hand-held Raman spectrometer to sort different carpets according to the types of surface layer fibers, such as PP, PA, PET

The fine picking process mainly focuses on nylon waste carpets (including nylon 6 and nylon 66)

Second,: grinding process

Firstly, feeding a whole carpet into a cutting machine, and cutting the whole carpet into carpet strips;

Secondly, the long broken carpet is fed into a first grinding mill. Wherein, the grinding mill is internally provided with a crushing roller, and mainly aims at tearing and crushing the carpet, a screen is arranged below the crushing roller, the size of the screen holes is fixed, impurities such as calcium carbonate, wax and the like are convenient to leak out from the holes, and the crushed carpet is changed into fine fibers from long strips after a grinding procedure;

The fine fibrous material then passes through multiple mills and multiple screens, each mill having built-in crushing rolls and screens of different mesh sizes to facilitate the escape of impurities such as calcium carbonate, wax, etc. of varying sizes from the holes. Finally, the microfiber is obtained. The aim of the multi-channel crushing is to fully remove impurities such as calcium carbonate, hard rubber layer and the like, and to improve the efficiency of centrifugal dispersion of PP and PA fibers in the subsequent process

A schematic of the multi-pass grinding and separation process is shown in figure 2.

The microfibers from this milling process have certain ash requirements and need to meet 5% -10%. If the requirements are met, the next production flow can be entered, and if the requirements are not met, reworking treatment is needed;

The material obtained by the grinding process also has certain fiber length distribution requirement, and the fiber length frequency distribution histogram is shown as follows, and the requirement that D50 is less than 0.8mm and more than or equal to 1mm meets the requirement of more than 60 percent is required. The batch meeting the requirements can enter the next production flow, and if the batch does not meet the requirements, the batch needs to be reworked again.

Third,: pulping process

The pulping process mainly aims at pretreating micro fibers and making mats for the subsequent centrifugal separation of PP and PA fibers

The pulping process comprises the following formula system

0.1 To 0.3 percent of defoaming agent

5 To 10 percent of ground microfiber

Distilled water 90% -95%

Specifically: the main function of the defoamer is to eliminate bubbles generated in the stirring process and avoid certain negative influence on uniform mixing between the microfibers and the water

Specifically: the density of the distilled water is 1.0g/cm3

Specifically: the ground microfiber is a product output in the first production link, and needs to meet the requirements of certain fiber length distribution and ash content;

Specifically: the pulping process is completed in a closed container, a metal stirrer is arranged in the container, and the defoamer, distilled water, microfiber and the like are uniformly mixed through continuous rotation, so that a uniform mixed system is finally formed.

Fourth,: wet centrifugal separation process:

the wet centrifugal separation process mainly uses the principle of centrifugal separation. I.e. when the heterogeneous system is rotated about a central axis, the objects within the system are subjected to centrifugal forces. If the particle density is greater than the liquid density, the particles will gradually move away from the central axis in the direction of the centrifugal force, and after a period of time, effective separation of substances with different densities can be achieved.

The density of the PA66 fiber is approximately 1.14g/cm < 3 >, and the density of the PP fiber is approximately 0.91-0.95g/cm < 3 >, so that the effective separation of the PA66 fiber and the PP fiber can be realized after the wet centrifugal separation

The centrifugal separation equipment keeps high-speed rotation during working, and the rotating speed of the main machine can be set at 3000RPMs-50000RPMs

The first outlet of the centrifugal separation equipment is mainly used for outputting nylon fibers, the water content is controlled to be about 2%, and nylon recovered particles can be obtained after subsequent drying, homogenization and extrusion granulation;

The second outlet of the centrifugal equipment mainly obtains circulating water, polypropylene byproducts, some impurities which are not effectively separated, and the like, and the target polypropylene byproducts can be obtained after the solid-liquid separation of the mixture, the vibration sieve and the like are collected

The target polypropylene byproduct has certain requirements on ash content, the ash content is controlled to be less than 5%, and if the requirements are not met, the target polypropylene byproduct needs to be returned to the pulping process again to be separated continuously.

The target polypropylene byproduct also needs to undergo DSC analysis test to determine the purity of the regenerated polypropylene. If the DSC curve only shows one melting peak at about 167 ℃, the requirement is met, and if the DSC curve shows two melting peaks at 167 ℃ and 260 ℃ at the same time, the PA content in the byproducts is too high, the purity of PP is insufficient, and the byproducts need to be returned to the pulping process again to continue separation.

A flow chart of the preparation of the high-purity polypropylene fluff is shown in figure 3.

The second densification process of the polypropylene fluff is mainly that the polypropylene fluff is sent into a closed tank, and is heated at high temperature in the tank to change the polypropylene fluff from fiber shape into block shape, and finally becomes granular polypropylene through equipment such as a conveyor belt, a multilayer vibrating screen and the like

The temperature of the closed tank is set to be about 155 ℃, namely the initial temperature of polypropylene melting, and the heating time is 15min-20min

The high purity polypropylene fluff by-product does not require further drying before feeding into the apparatus because the moisture contained in the by-product is vaporized during heating;

The necessity of the densification treatment of the polypropylene fluff is that on one hand, the moisture of the polypropylene reclaimed material is removed, and on the other hand, the subsequent extrusion processing is convenient, and the accurate feeding is realized;

the third blending and modifying production link comprises the following detailed formula system:

50 to 85 percent of regenerated polypropylene raw material

0.5 To 1 percent of tackifier

Antioxidant 1-3%

10-40% Of glass fiber

2 To 5 percent of compatilizer

1% Of color master batch.

Specifically, the regenerated polypropylene raw material is regenerated polypropylene particles treated by a densification process, and is characterized by high purity, low water content and low ash content, and the raw material is granular, so that accurate feeding is facilitated;

Specifically, the tackifier is mainly an organic peroxide molecular cross-linking agent, and a small amount of the cross-linking agent is helpful for improving the number average molecular weight of polypropylene, so that the negative influence of performance loss caused by molecular weight degradation is reduced;

Specifically, the antioxidant mainly comprises a main antioxidant of hindered phenols and an auxiliary antioxidant of phosphite esters or thioesters;

Specifically, the compatilizer is a maleic anhydride grafted polypropylene polymer, has the characteristic of high grafting rate, and plays a role in increasing compatibility in the whole composite material system;

specifically, the glass fiber is short glass fiber with the fiber length of 2mm-4mm and the glass fiber diameter of about 10 microns, and the surface of the glass fiber is covered with a coupling agent and a surface impregnating compound, so that better interface bonding strength can be obtained

Specifically, the color master batch mainly takes PP or PE as a base material and has good compatibility with the main materials of the formula

The preparation flow of blending modification is as follows:

firstly, adding polypropylene reclaimed materials, tackifier, antioxidant, compatilizer, masterbatch and the like into a mixer according to corresponding proportions, and uniformly mixing;

Secondly, pouring the mixture into a feed opening of an extruder, and simultaneously pouring the short glass fibers into a side feed opening;

thirdly, starting the extruder, a cold water tank, a granulator, an air dryer, a vibrating screen, an oven and the like, and setting corresponding equipment parameters according to a production instruction sheet;

Finally, the molten material flows out of a die head of an extruder, is cooled into a material strip by water, and is air-dried, granulated and dried to form the glass fiber reinforced regenerated polypropylene composite material;

The invention has the beneficial effects that

First: the waste is changed into valuable, and the environment is protected. The nylon by-product originally needs to be buried and incinerated, and the use value is recovered through recycling the nylon by-product, and the economic development number of recycling is-!

Second,: the prepared composite material has very low cost, and has wide market economic value and market competitiveness;

third,: good performance, can meet the performance requirements of products with low bearing requirements in the industries of automobiles, mechanical equipment and the like;

fourth,: the resources may be persistent. The method for replacing the new material by the return material reduces the requirement of a part of the new material, saves the resource-!

Drawings

FIG. 1 is a flow chart of the production of a recycled polypropylene composite material;

FIG. 2 is a schematic diagram of a multi-pass grinding and separation process;

FIG. 3 is a flow chart of the preparation of high purity polypropylene fluff.

Detailed description of the preferred embodiments

Raw materials

Waste nylon carpet and market recycling

Polypropylene resin, BX3900, SK chemistry

Defoamer, ANTROXL, company Rona-Planck

Distilled water, technical grade, commercially available,

Tackifier, dicumyl peroxide (DCP), commercially available

Antioxidant 1010, hindered phenol antioxidant, molecular weight 1178, double bond chemical;

Antioxidant 619F, thiodipropionic acid distearate, molecular weight 732, double bond chemical industry;

chopped glass fiber, 305H, chongqing International composite Material Co., ltd

Compatibilizing agent, HW-501, jiaxing Wen chemical Co., ltd

Black masterbatch, 0452, special for PP, jiangsu sea New Material Co., ltd

Material performance testing method

Density test standard: ISO 1183; units: g/cm3; dipping method

Ash test standard: ISO 3451; units: the%; test conditions: 625 deg.c;

Tensile strength test standard: ISO 527; units: MPa; test conditions: tensile modulus of elasticity test standard at a tensile speed of 5 mm/min: ISO 527; units: MPa; test conditions: tensile speed 1mm/min flexural strength test standard: ISO 178; units: MPa; test conditions: 2mm/min,64mm

Flexural modulus test standard: ISO 178; units: MPa; test conditions: 2mm/min,64mm impact strength test standard: ISO 179; units: KJ/m2; test conditions: notched impact strength test at 23 ℃): ISO 179; units: KJ/m2; test conditions: thermal deformation temperature test standard at 23 ℃): ISO 75; units: the temperature is lower than the temperature; test conditions: 1.8MPa,120 ℃/h thermo-oxidative aging performance unit: % test conditions: tensile strength change rate heat curing performance unit at 140 ℃ for 1000 hours: % test conditions: rate of change of notched impact strength at 140℃for 1000h

Flow direction shrinkage unit: % test conditions: testing after 48h

Vertical flow direction shrinkage unit: % test conditions: testing after 48h

Example 1

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is subjected to pulping, centrifugal separation and densification in sequence, and finally the granular regenerated polypropylene raw material with high purity (no melting peak of PA6 or PA66 in a DSC curve) and low ash content (ash content is less than 5%) is obtained. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 84.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the raw material is put into a main feeding port, glass fibers are put into a side feeding port (10 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Example 2

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is subjected to pulping, centrifugal separation and densification in sequence, and finally the granular regenerated polypropylene raw material with high purity (no melting range of PA6 or PA66 in a DSC curve) and low ash content (ash content is less than 5%) is obtained. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 74.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the mixture is put into a main feeding port, glass fibers are put into a side feeding port (20 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Example 3

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is subjected to pulping, centrifugal separation and densification in sequence, and finally the granular regenerated polypropylene raw material with high purity (no melting range of PA6 or PA66 in a DSC curve) and low ash content (ash content is less than 5%) is obtained. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 64.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the mixture is put into a main feeding port, glass fibers are put into a side feeding port (30 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Example 4

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is subjected to pulping, centrifugal separation and densification in sequence, and finally the granular regenerated polypropylene raw material with high purity (no melting range of PA6 or PA66 in a DSC curve) and low ash content (ash content is less than 5%) is obtained. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 54.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the raw material is put into a main feeding port, glass fibers are put into a side feeding port (40 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Comparative example 1

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is sequentially subjected to pulping, centrifugal separation and densification treatment to finally obtain the granular regenerated polypropylene raw material with the ash content of 9%. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 74.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the mixture is put into a main feeding port, glass fibers are put into a side feeding port (20 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Comparative example 2

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. The fiber wool is subjected to pulping, centrifugal separation and densification treatment in sequence, and finally the granular regenerated polypropylene raw material with the ash content of 9% is obtained. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 75kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the raw material is put into a main feeding port, glass fibers are put into a side feeding port (20 kg), after extrusion blending, molten material flowing out of a die head is cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Comparative example 3

Sorting the recovered waste carpets, screening nylon carpets, and sequentially carrying out crushing and screening, multi-channel crushing and screening on the nylon carpets to finally form 5% -10% ash, wherein the length of D50 fibers is less than 0.8mm; the distribution probability of the fiber length is more than or equal to 1mm and is more than or equal to 60 percent. After pulping, centrifugal separation and densification treatment are sequentially carried out on the fiber wool, and finally DSC tests are carried out, the melting peaks of PA66 and PP are found to be contained in the granular regenerated polypropylene raw material. The regenerated polypropylene raw material, tackifier, antioxidant, compatilizer, masterbatch and the like are mixed uniformly according to a proportion (wherein the regenerated polypropylene raw material is 74.5kg, the tackifier is 0.5kg, the antioxidant is 2kg, the compatilizer is 2kg, the masterbatch is 1 kg), the mixture is put into a main feeding port, glass fibers are put into a side feeding port (20 kg), after extrusion blending, molten material strips flowing out of a die head are cooled by water, and the regenerated polypropylene glass fiber reinforced composite material can be obtained after air drying, granulating and drying.

Comparative example 4

75Kg of polypropylene resin BX3900, 1kg of antioxidant 1010,1kg of antioxidant DSTP,2kg of compatilizer HW-501 and 1kg of black masterbatch are put into a main feeding port, 20kg of glass fiber is put into a side feeding port, after extrusion blending, molten material strips flowing out of a die head are cooled by water, and after air drying, granulating and drying, the new polypropylene glass fiber reinforced composite material is obtained.

As can be seen from the above table, the data,

(1) As can be seen from the material data of examples 1 to 4, the tensile, bending, impact and other properties of the composite material are gradually improved along with the increase of the glass fiber content, so that the regenerated polypropylene modified composite material with corresponding grade can be selected based on different application scenes of the parts.

(2) From the material data of examples 1 to 4, it can be seen that the low-carbon environment-friendly and low-cost regenerated polypropylene modified composite material can meet the development requirements of certain automobile plastic parts. For example, ford WSS-M4D854-B1, the standard prescribes part application of G30 materials in aspects of automobile fans, storage battery trays and the like, wherein the ash content of the prescribed materials is 27% -33%, the density is 1.08G/cm < 3 > -1.16G/cm < 3 >, the tensile strength is more than or equal to 55MPa, the tensile elastic modulus is more than or equal to 4000MPa, the flexural modulus is more than or equal to 4000MPa, the notch impact strength is more than or equal to 6KJ/M < 2 >, the thermal deformation temperature is more than or equal to 130 ℃, the thermal aging change rate of the tensile strength and the notch impact strength is +/-25%, and the physical property data of the embodiment 3 can meet the material standard requirements.

(3) From the data of example 2 and comparative example 1, it can be seen that when the ash content of the by-product polypropylene fluff is high, the strength properties of the finished product, including tensile strength, flexural strength and impact strength, are affected subsequently after the preparation of the recycled polypropylene composite.

(4) As can be seen from the data of example 2 and comparative example 2, if the PA66 content of the by-product polypropylene fluff is high, the polypropylene purity is insufficient, and the strength performance of the finished product is also affected, mainly because of the incompatibility of the polypropylene material and the polyamide material, the interfacial strength is low, and a weak link of mechanics is easily formed in the stretching process;

(5) As can be seen from the data of example 2 and comparative example 3, the addition of a proportion of tackifier to the extrusion formulation is beneficial to improving the mechanical properties of the overall composite!

(6) As can be seen from the data of the embodiment 2 and the comparative example 4, compared with the performance of the completely new material, the performance loss rate of the regenerated polypropylene composite material in the strength aspect reaches about 25 percent, but the material has unique application advantages in various industries such as household appliances, electronic appliances, mechanical equipment, automobile industry and the like due to the characteristics of sustainable material circulation, low carbon and environmental protection, low cost and the like.

While the invention has been described with respect to the preferred embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the principles of the invention, and equivalents thereof, in terms of construction, feature, and principle are intended to be encompassed by the present claims.

Claims (9)

1. The preparation method of the regenerated polypropylene composite material based on the waste nylon carpet recycling byproducts is characterized by mainly comprising three production links:

first: the main aim of the fine sorting and separation of the waste carpets is to separate the byproduct polypropylene from the waste nylon carpet system to obtain high-purity polypropylene fluff;

second,: the densification treatment of the polypropylene fluff mainly comprises the steps of processing the fluff into polymer particles, and facilitating the subsequent extrusion production and accurate feeding;

Third,: blending and modifying the regenerated polypropylene material.

2. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts, which is disclosed in claim 1, is characterized in that: the fine sorting and separating link mainly comprises the following steps:

(1) Sorting, namely sorting different carpets by using a handheld Raman spectrometer, and classifying according to the types of surface layer fibers, such as PP, PA, PET;

(2) A grinding procedure, namely, firstly, feeding the whole carpet into a cutting machine to be crushed into long carpet strips, and then feeding the long crushed carpet into a grinding machine to change the long crushed carpet into fine fibers; subsequently, the fine fibrous material passes through a plurality of grinding mills and a plurality of screens to finally form microfibers;

(3) And in the pulping process, water is injected, and a defoaming agent is added to form a water and fiber mixed system. The main purpose of the process is to pretreat the fibers and prepare mats for the subsequent centrifugal separation of PP and PA fibers;

(4) And (3) centrifugal separation, wherein the effective separation of different substances is finally realized by the centrifugal force generated by high-speed rotation based on the difference between the PA fiber density of 1.13g/cm < 3 > -1.15g/cm < 3 > and the PP fiber density of 0.90g/cm < 3 > -0.92cm < 3 >.

3. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts according to claim 2, which is characterized in that: the microfibers produced in the grinding process have certain ash content requirements and fiber length distribution requirements, wherein the ash content needs to meet 5% -10%, the fiber length distribution needs to meet the requirements that D50 is less than 0.8mm and more than or equal to 1mm meets the requirements of more than 60%; the batch meeting the requirements can enter the next production flow, and if the batch does not meet the requirements, the batch needs to be reworked again.

4. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts according to claim 2, which is characterized in that: in the pulping process, each component in the mixed system is as follows

0.1% -0.3% Of defoaming agent;

grinding 5% -10% of microfibers;

90% -95% of distilled water.

5. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts, which is disclosed in claim 1, is characterized in that: the polypropylene fluff centrifugally separated has certain ash content and melting peak requirements; wherein ash content is controlled to be less than 5%, DSC curve only shows a melting peak of 167 ℃ polypropylene, two melting peaks of 167 ℃ and 260 ℃ are not simultaneously generated, and batch meeting the requirement can enter the next production flow, if not meeting the requirement, reworking treatment is needed.

6. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts, which is disclosed in claim 1, is characterized in that: in the densification production link, the by-product polypropylene fluff is sent into a closed tank, the temperature in the tank is set to be about 155 ℃, namely the initial temperature of polypropylene melting, and the heating time is 15-20 min.

7. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts, which is disclosed in claim 1, is characterized in that: the formula system of the blending and modifying production link is as follows:

50% -85% of regenerated polypropylene raw material;

0.5% -1% of tackifier;

1% -3% of antioxidant;

10-40% of glass fiber;

2% -5% of a compatilizer;

1% of color master batch.

8. The method for preparing the recycled polypropylene composite material based on the waste nylon carpet recycling byproducts, which is disclosed in claim 7, is characterized in that: the components of the formula system are as follows:

(1) The regenerated polypropylene raw material, namely the product after densification process, is characterized in that the polypropylene has high purity, low water content and low ash content, and the raw material is granular, thus being convenient for accurate feeding;

(2) The tackifier is mainly a molecular cross-linking agent of organic peroxides, and a small amount of cross-linking agent is helpful for improving the number average molecular weight of polypropylene, so that the negative influence of performance loss caused by molecular weight degradation is reduced;

(3) The antioxidant mainly comprises a main antioxidant of hindered phenols and an auxiliary antioxidant of phosphite esters or thioesters;

(4) The compatilizer is a maleic anhydride grafted polypropylene polymer and has the characteristic of high grafting rate, and plays a role in increasing the interface combination between glass fiber and resin in the whole composite material system;

(5) The glass fiber is short glass fiber, the fiber length is 2mm-4mm, the glass fiber diameter is small, about 10 microns, and the surface of the glass fiber is covered with a coupling agent and a surface impregnating compound, so that better interface binding force can be obtained;

(6) The color master batch mainly takes PE or PP as a base material and has good compatibility with a main material.

9. The recycled polypropylene composite material based on waste nylon carpet recycling byproducts according to claim 1, wherein the recycled polypropylene composite material is characterized in that: the production steps of the blending and modifying links are as follows:

firstly, adding polypropylene reclaimed materials, tackifier, antioxidant, compatilizer, masterbatch and the like into a mixer according to corresponding proportions, and uniformly mixing;

Secondly, pouring the mixture into a feed opening of an extruder, and pouring the short glass fibers into a side feed opening;

Thirdly, starting the extruder, a cold water tank, a granulator, an air dryer, a vibrating screen, a baking oven and other equipment, and setting corresponding equipment parameters according to the production instruction sheet;

Finally, the melted material flows out from a die head of an extruder, is cooled into a material strip by water, and is air-dried, granulated and dried to form the glass fiber reinforced regenerated polypropylene composite material.