CN114672158A - High-strength composite material based on regenerated nylon and preparation method thereof - Google Patents

Abstract

The invention relates to a high-strength composite material based on regenerated nylon and a preparation method thereof, belonging to the technical field of environment-friendly nylon composite materials. The composite material comprises 40-50 parts of regenerated nylon chips, 30-40 parts of matrix particles, 15-25 parts of polyolefin, 5-10 parts of reinforcing filler, 5-20 parts of glass fiber and 1-5 parts of auxiliary agent according to parts by weight, the strength index of the composite material is similar to that of nylon 66, and the reinforced regeneration of nylon is realized; the invention provides a regeneration method of waste nylon material at the same time, regard trifluoroethanol as the solvent, compound a small amount of phosphotungstic acid as depolymerizing catalyst, filter, decolorize nylon after slightly depolymerizing, reuse N-acetyl caprolactam and sodium hydroxide catalytic polymerization, realize the regeneration of nylon; in addition, the reinforcing filler added in the composite material takes nano silicon dioxide as a core and maleic anhydride, styrene and vinyl triethoxysilane as coating layers, and can be uniformly dispersed to achieve the reinforcing effect.

Description

High-strength composite material based on regenerated nylon and preparation method thereof

Technical Field

The invention belongs to the technical field of environment-friendly nylon composite materials, and particularly relates to a high-strength composite material based on regenerated nylon and a preparation method thereof.

Background

The polyamide is commonly called nylon, and has the advantages of unique low specific gravity, high tensile strength, wear resistance, good self-lubricating property, excellent impact toughness, and rigidity and flexibility, thereby gaining attention of people, and in addition, the polyamide has simple and convenient processing, high efficiency and light specific gravity (only 1/7 of metal), can be processed into various products to replace metal, is widely used in the automobile and transportation industry, and has higher economic benefit in the recovery of the nylon.

In the prior art, a recycling method for nylon is to melt waste nylon and then mix the waste nylon with pure nylon to prepare a product, wherein the waste nylon is usually mixed with impurities such as chips, pigments and the like, and the waste nylon is subjected to high-temperature banburying for many times and then has a serious oxidation degree, and is generally only used in products with low strength requirements, so that the recycling of nylon is greatly limited.

Disclosure of Invention

In order to solve the technical problems mentioned in the background art, the invention aims to provide a high-strength composite material based on recycled nylon and a preparation method thereof.

The purpose of the invention can be realized by the following technical scheme:

a high-strength composite material based on regenerated nylon comprises the following components in parts by weight: 40-50 parts of regenerated nylon slices, 30-40 parts of matrix particles, 15-25 parts of polyolefin, 5-10 parts of reinforcing filler, 5-20 parts of glass fiber and 1-5 parts of auxiliary agent;

the regenerated nylon chip is prepared by the following steps:

step A1: crushing the recovered nylon waste, adding the crushed recovered nylon waste into a stirring kettle, adding trifluoroethanol into phosphotungstic acid, mixing to prepare a dissolved solution, pouring the dissolved solution into the stirring kettle, stirring, heating to 50-60 ℃, completely dissolving the recovered nylon, filtering the dissolved solution, removing insoluble impurities in the recovered nylon, and decoloring the filtrate by using a decoloring column to prepare an impurity-removed dissolved solution;

in the solution, trifluoroethanol is used as a solvent, a small amount of phosphotungstic acid is compounded to be used as a depolymerization catalyst, and nylon is slightly depolymerized, so that the recovered nylon can be dissolved into a solution with lower viscosity at a lower temperature, impurity filtration and impurity adsorption treatment are facilitated, energy is saved compared with the conventional pyrolysis process, and the condition that the recovered nylon is aged in a high-temperature environment for a long time is avoided.

Furthermore, the dosage ratio of the trifluoroethanol to the phosphotungstic acid is 0.65-0.72 g/L.

Step A2: introducing the impurity-removing solution into a reaction kettle, adding an antioxidant into the reaction kettle, stirring at 75-80 ℃ until the viscosity of a reaction system reaches 4000cP, dissolving N-acetyl caprolactam and sodium hydroxide in ethanol, adding into the reaction kettle, heating to 145-160 ℃, stirring for 2-3h, repolymerizing the slightly depolymerized impurity-removing solution into nylon resin with higher purity under the catalysis of the N-acetyl caprolactam and the sodium hydroxide, realizing high-quality recovery of nylon, cooling, drying, and crushing to prepare regenerated nylon chips.

Further, the antioxidant is a phosphite antioxidant.

Further, the total amount of N-acetyl caprolactam and sodium hydroxide is 0.25 to 0.3 wt% of the recycled nylon wastes.

The reinforcing filler is prepared by the following steps:

step B1: respectively dissolving maleic anhydride, styrene and vinyl triethoxysilane in toluene to obtain respective toluene solution, drying the toluene before use, dissolving azobisisobutyronitrile in absolute ethanol, adding the toluene solution of maleic anhydride, stirring and mixing, adding the toluene solution of styrene, stirring and mixing, heating to 90-100 ℃, carrying out polymerization reaction for 28-35min, cooling to 60-70 ℃, adding the toluene solution of vinyl triethoxysilane, keeping the temperature and stirring for 40-60min to obtain a coating material;

step B2: adding nano silicon dioxide into an ethanol solution, stirring, mixing, standing for 24 hours, centrifuging the mixed solution, and removing the ethanol solution to obtain pretreated nano silicon dioxide;

step B3: ultrasonically dispersing the pretreated nano silicon dioxide in acetone, adding the dispersion liquid into a coating material, stirring and mixing, then carrying out reduced pressure rotary evaporation, removing toluene, acetone and ethanol, carrying out vacuum drying to constant weight, and finally crushing a dried product by using a crusher to obtain a reinforced filler; the coating material is a copolymer of maleic anhydride, styrene and vinyl triethoxysilane, a silicon-oxygen bond is arranged on a side chain, and the silicon-oxygen bond and hydroxyl on the surface of the pretreated nano silicon dioxide can form a hydrogen bond, so that the coating material can be tightly attached to the surface of the nano silicon dioxide.

Further, the molar ratio of the maleic anhydride, the styrene and the vinyltriethoxysilane used is 2:2: 1.

Furthermore, the mass ratio of the amount of the pretreated nano silicon dioxide to the total amount of maleic anhydride, styrene and vinyltriethoxysilane is 1: 0.08-0.12.

A preparation method of a high-strength composite material based on regenerated nylon comprises the following steps:

step S1: mixing the regenerated nylon chips, the matrix particles, the polyolefin and the auxiliary agent according to the weight part ratio, then, carrying out densification to obtain a sizing material, and then, adding the reinforcing filler and the glass fiber for mixing to obtain a mixture;

step S2: and extruding, cooling and granulating the mixture to prepare the high-strength composite material.

Further, the polyolefin is selected from one of polyethylene and polystyrene.

Further, the auxiliary agent comprises an antioxidant and a defoaming agent.

The invention has the beneficial effects that:

1. the invention provides a nylon-based composite material, which has the strength index similar to that of nylon 66, and about 30 percent of regenerated nylon is added in the raw material, so that the reinforced regeneration of nylon is realized.

2. The invention provides a regeneration method of a waste nylon material, which takes trifluoroethanol as a solvent, compounds a small amount of phosphotungstic acid as a depolymerization catalyst, depolymerizes nylon slightly, so that the recovered nylon can be dissolved into a solution with lower viscosity at a lower temperature, is beneficial to removing impurities and decoloring in the waste nylon, improves the purity of the recovered nylon, saves more energy compared with the prior pyrolysis process, simultaneously avoids the aging of the recovered nylon in a high-temperature environment for a long time, then carries out catalytic polymerization by using N-acetylcaprolactam and sodium hydroxide, and obtains a regenerated nylon slice through post-treatment.

3. The invention provides a reinforced filler, which takes nano-silica as a core, takes a copolymer of maleic anhydride, styrene and vinyl triethoxysilane as a coating layer, has good dispersibility in a nylon matrix, introduces a silicon-oxygen bond on a side chain, and is combined with hydroxyl on the surface of pretreated nano-silica, so that the coating material is attached to the surface of the nano-silica and has good bonding strength, and is not easy to strip from a base material during working.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment of preparing a regenerated nylon chip comprises the following steps:

step A1: taking 6kg of recycled nylon 6 waste, putting the waste into a crusher, crushing the waste into particles with the particle size not more than 5mm, taking 20L of trifluoroethanol, adding 13g of phosphotungstic acid, stirring and dissolving to prepare a dissolved solution, adding the waste and the dissolved solution into a stirring kettle, starting stirring and heating, heating to 50 ℃, keeping the temperature and stirring to completely dissolve the waste, taking the trifluoroethanol as a solvent in the dissolved solution, compounding a small amount of phosphotungstic acid as a depolymerization catalyst, slightly depolymerizing nylon to enable the recycled nylon to be dissolved into the dissolved solution with lower viscosity at a lower temperature, filtering the dissolved solution by using a 30-mesh filter screen, filtering insoluble impurities, introducing the filtrate into an activated carbon decolorizing column for decolorizing treatment to prepare the impurity-removed dissolved solution, and compared with the existing pyrolysis process, the energy-saving effect is better, and meanwhile, the recycled nylon is prevented from aging for a long time under a high-temperature environment;

step A2: introducing the impurity-removed solution into a reaction kettle, adding 5g of tris (2, 4-tert-butylphenyl) phosphite serving as an antioxidant into the reaction kettle, heating to 75 ℃, stirring until the viscosity of a reaction system reaches 4000cP, dissolving 5g of N-acetylcaprolactam and 10g of sodium hydroxide in 400mL of ethanol, adding the mixture into the reaction kettle, heating to 145 ℃, stirring for 3 hours, polymerizing the slightly depolymerized impurity-removed solution into nylon resin with higher purity under the catalysis of the N-acetylcaprolactam and the sodium hydroxide, realizing high-quality recovery of nylon, cooling, drying in a drying oven for 10 hours at 60 ℃, and crushing by a crusher until the particle size is not more than 5mm to prepare regenerated nylon chips.

Example 2

Step A1: taking 6kg of recycled nylon 6 waste, putting the waste into a crusher, crushing the waste into particles with the particle size not more than 5mm, taking 20L of trifluoroethanol, adding 14.4g of phosphotungstic acid, stirring and dissolving to prepare a dissolved solution, adding the waste and the dissolved solution into a stirring kettle, starting stirring and heating, heating to 60 ℃, keeping the temperature and stirring to completely dissolve the waste, taking trifluoroethanol as a solvent in the dissolved solution, compounding a small amount of phosphotungstic acid as a depolymerization catalyst, slightly depolymerizing nylon to enable the recycled nylon to be dissolved into the dissolved solution with lower viscosity at a lower temperature, filtering the dissolved solution by using a 30-mesh filter screen, filtering insoluble impurities, introducing the filtrate into an active carbon decolorizing column for decolorizing treatment to prepare an impurity-removed dissolved solution, and compared with the existing pyrolysis process, the energy-saving effect is higher, and meanwhile, the recycled nylon is prevented from being aged in a high-temperature environment for a long time;

step A2: pouring the impurity-removed solution into a reaction kettle, adding 5g of tris (2, 4-tert-butylphenyl) phosphite serving as an antioxidant into the reaction kettle, heating to 80 ℃, stirring until the viscosity of a reaction system reaches 4000cP, dissolving 9g of N-acetylcaprolactam and 9g of sodium hydroxide into 500mL of ethanol, adding the mixture into the reaction kettle, heating to 160 ℃, stirring for 2 hours, polymerizing the slightly depolymerized impurity-removed solution into nylon resin with higher purity under the catalysis of the N-acetylcaprolactam and the sodium hydroxide, realizing high-quality recovery of nylon, cooling, drying in a drying oven for 10 hours at 60 ℃, crushing by a crusher until the particle size is not more than 5mm, and preparing the regenerated nylon chips.

Example 3

In this example, a reinforcing filler is prepared, and the specific implementation process is as follows:

step B1: respectively dissolving 9.8g of maleic anhydride, 10.4g of styrene and 9.5g of vinyltriethoxysilane in toluene, drying the toluene before using, dissolving 0.2g of azobisisobutyronitrile in absolute ethanol, adding the toluene solution of maleic anhydride, stirring and mixing, adding the toluene solution of styrene, stirring and mixing, heating to 90 ℃, carrying out polymerization reaction for 35min, cooling to 60 ℃, adding the toluene solution of vinyltriethoxysilane, keeping the temperature and stirring for 60min to obtain a coating material;

step B2: adding 370g of nano silicon dioxide into 2L of 60% ethanol aqueous solution, stirring, mixing, standing for 24h, centrifuging the mixed solution, and pouring out the ethanol aqueous solution to obtain pretreated nano silicon dioxide;

step B3: ultrasonically dispersing the pretreated nano silicon dioxide in 3L of acetone, adding the dispersion liquid into the coating material, stirring and mixing, then carrying out reduced pressure rotary evaporation, removing toluene, acetone and ethanol, carrying out vacuum drying to constant weight, and finally crushing the dried product by using a crusher to pass through a 80-mesh screen to obtain the reinforced filler.

Example 4

In this example, a reinforcing filler is prepared, and the specific implementation process is as follows:

step B1: respectively dissolving 9.8g of maleic anhydride, 10.4g of styrene and 9.5g of vinyltriethoxysilane in toluene, drying the toluene before using, dissolving 0.2g of azobisisobutyronitrile in absolute ethanol, adding the toluene solution of maleic anhydride, stirring and mixing, adding the toluene solution of styrene, stirring and mixing, heating to 100 ℃, carrying out polymerization reaction for 28min, cooling to 70 ℃, adding the toluene solution of vinyltriethoxysilane, keeping the temperature and stirring for 40min to obtain a coating material;

step B2: adding 245g of nano silicon dioxide into 1.5L of 60% ethanol aqueous solution, stirring, mixing, standing for 24h, centrifuging the mixed solution, and pouring out the ethanol aqueous solution to obtain pretreated nano silicon dioxide;

step B3: ultrasonically dispersing the pretreated nano silicon dioxide in 2L of acetone, adding the dispersion liquid into the coating material, stirring and mixing, then carrying out reduced pressure rotary evaporation, removing toluene, acetone and ethanol, carrying out vacuum drying to constant weight, and finally crushing the dried product by using a crusher to pass through a 80-mesh screen to obtain the reinforced filler.

Example 5

In this embodiment, a high-strength composite material based on recycled nylon is prepared by using the recycled nylon chips prepared in example 1 and the reinforcing filler prepared in example 3 as raw materials, and the specific implementation process is as follows:

step S1, metering raw materials:

example preparation 1 prepared 2kg of regenerated nylon chips;

1.5kg of nylon 6 particles as matrix particles;

750g of polyethylene as a polyolefin additive;

500g of reinforcing filler prepared in example 3;

500g of glass fiber;

mixing commercially available defoaming agent DU-402 and antioxidant 1010 according to the mass ratio of 1:1 to obtain an auxiliary agent, and taking 50g of the auxiliary agent;

step S2: mixing the regenerated nylon chips, the matrix particles, the polyolefin and the auxiliary agent, adding the mixture into an internal mixer, mixing the mixture into a sizing material at 225 +/-3 ℃, adding the glass fiber and the reinforcing filler, and continuously mixing the mixture until the mixture is completely mixed to prepare a mixture;

step S3: and extruding, cooling and granulating the mixture by a screw extruder to prepare the high-strength composite material.

Example 6

In this embodiment, the regenerated nylon chip prepared in example 2 and the reinforcing filler prepared in example 4 are used as raw materials to prepare a high-strength composite material based on regenerated nylon, and the specific implementation process is as follows:

step S1, raw material metering:

example preparation 2.5kg of regenerated nylon chip;

2kg of nylon 6 particles as base particles;

1.25kg of polyethylene as a polyolefin additive;

250g of reinforcing filler prepared in example 4;

2kg of glass fiber;

mixing commercially available defoaming agent DU-402 and antioxidant 1010 according to the mass ratio of 1:1 to obtain an auxiliary agent, and taking 250g of the auxiliary agent;

step S2: mixing the regenerated nylon chips, the matrix particles, the polyolefin and the auxiliary agent, adding the mixture into an internal mixer, mixing the mixture into a sizing material at 225 +/-3 ℃, adding the glass fiber and the reinforcing filler, and continuously mixing the mixture until the mixture is completely mixed to prepare a mixture;

step S3: and extruding, cooling and granulating the mixture by a screw extruder to prepare the high-strength composite material.

Example 7

In this embodiment, the regenerated nylon chip prepared in example 1 and the reinforcing filler prepared in example 4 are used as raw materials to prepare a high-strength composite material based on regenerated nylon, and the specific implementation process is as follows:

step S1, raw material metering:

example preparation 1. the regenerated nylon chip prepared was 2.25 kg;

2kg of nylon 6 particles as base particles;

1kg of polystyrene as a polyolefin additive;

500g of reinforcing filler prepared in example 4;

1kg of glass fiber;

mixing commercially available defoaming agent DU-402 and antioxidant 1010 according to the mass ratio of 1:1 to obtain an auxiliary agent, and taking 150g of the auxiliary agent;

step S2: mixing the regenerated nylon chips, the matrix particles, the polyolefin and the auxiliary agent, adding the mixture into an internal mixer, mixing the mixture into a sizing material at the temperature of 240 +/-3 ℃, adding the glass fiber and the reinforcing filler, and continuously mixing the mixture until the mixture is completely mixed to prepare a mixture;

step S3: and extruding, cooling and granulating the mixture by a screw extruder to prepare the high-strength composite material.

Comparative example 1

This comparative example is a commercially available reinforced nylon 66 pellet.

The composite materials prepared in examples 5 to 7 and comparative example 1 were used as raw materials to perform performance tests, and specific test items and test data are shown in table 1:

TABLE 1

As can be seen from the data in Table 1, the composite material prepared by the invention has the tensile strength of 162-188MPa, the bending strength of 258-270MPa and the strength index close to that of nylon 66 in the prior art, and realizes the reinforced regeneration of nylon.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims (7)

1. A high-strength composite material based on regenerated nylon is characterized by comprising the following components in parts by weight: 40-50 parts of regenerated nylon slices, 30-40 parts of matrix particles, 15-25 parts of polyolefin, 5-10 parts of reinforcing filler, 5-20 parts of glass fiber and 1-5 parts of auxiliary agent;

the regenerated nylon chip is prepared by the following steps:

step A1: crushing the recovered nylon waste, adding a solution prepared from trifluoroethanol and phosphotungstic acid, stirring, heating to 50-60 ℃ to dissolve the recovered nylon, and then filtering and decoloring to obtain an impurity-removed solution;

step A2: mixing the impurity-removed solution and an antioxidant, stirring at 75-80 ℃ until the viscosity of a reaction system reaches 4000cP, dissolving N-acetyl caprolactam and sodium hydroxide in ethanol, adding the solution into the reaction system, heating to 145-160 ℃, stirring for 2-3h, cooling, drying and crushing to prepare the regenerated nylon slice.

2. The high-strength composite material based on recycled nylon of claim 1, wherein the amount ratio of the trifluoroethanol to the phosphotungstic acid is 0.65-0.72 g/L.

3. The high strength composite material based on recycled nylon of claim 1, wherein the total amount of N-acetyl caprolactam and sodium hydroxide is 0.25-0.3 wt% of the recycled nylon waste.

4. The recycled nylon-based high strength composite of claim 1, wherein the reinforcing filler is prepared by the steps of:

step B1: respectively dissolving maleic anhydride, styrene and vinyl triethoxysilane in toluene, dissolving azobisisobutyronitrile in absolute ethanol, adding a toluene solution of maleic anhydride, stirring and mixing, adding a toluene solution of styrene, stirring and mixing, heating to 90-100 ℃, carrying out polymerization reaction for 28-35min, cooling to 60-70 ℃, adding a toluene solution of vinyl triethoxysilane, keeping the temperature and stirring for 40-60min to obtain a coating material;

step B2: adding nano silicon dioxide into an ethanol solution, stirring, mixing, standing for 24 hours, and centrifuging the mixed solution to obtain pretreated nano silicon dioxide;

step B3: ultrasonically dispersing the pretreated nano silicon dioxide in acetone, adding the dispersion liquid into the coating material, stirring and mixing, then carrying out reduced pressure rotary evaporation, carrying out vacuum drying to constant weight, and crushing to obtain the reinforced filler.

5. The high strength composite material based on recycled nylon of claim 4, wherein the molar ratio of the maleic anhydride, the styrene and the vinyltriethoxysilane is 2:2: 1.

6. The high-strength composite material based on the regenerated nylon of claim 4, wherein the mass ratio of the amount of the pretreated nano-silica to the total amount of the maleic anhydride, the styrene and the vinyltriethoxysilane is 1: 0.08-0.12.

7. A preparation method of a high-strength composite material based on regenerated nylon is characterized by comprising the following steps:

step S1: mixing the regenerated nylon chips, the matrix particles, the polyolefin and the auxiliary agent according to the weight part ratio, then, densely refining the mixture into a sizing material, and then, adding the reinforced filler and the glass fiber for mixing to obtain a mixture;

step S2: and extruding, cooling and granulating the mixture to prepare the high-strength composite material.