CN113943408B

CN113943408B - Polymer-based composite material foaming part and preparation method thereof

Info

Publication number: CN113943408B
Application number: CN202010688036.9A
Authority: CN
Inventors: 王剑磊
Original assignee: Fujian Quanzhou Haibin Protective Armanments Co ltd
Current assignee: Fujian Quanzhou Haibin Protective Armanments Co ltd
Priority date: 2020-07-16
Filing date: 2020-07-16
Publication date: 2022-09-06
Anticipated expiration: 2040-07-16
Also published as: CN113943408A

Abstract

The invention provides a polymer matrix composite material foaming product and a preparation method thereof, wherein an ultraviolet light source and microwaves are adopted for the product as curing energy sources, and material formula design is combined, so that resin is subjected to secondary curing, the mechanical property of the product is improved, in the microwave treatment process, a polar monomer is rapidly heated and heated under the action of microwaves, thermal expansion and curing reaction of thermoplastic expansion microspheres occur simultaneously, pores are formed and shaped, and the 3D printing foaming product with excellent performance is prepared.

Description

Polymer-based composite material foaming part and preparation method thereof

Technical Field

The invention belongs to the technical field of composite material manufacturing, and particularly relates to a polymer matrix composite material foaming product and a preparation method thereof.

Background

The polymer foaming material is widely applied to the industries of daily necessities, vehicles, packaging materials, insulating materials, electronic products, textiles and the like, and the annual composite growth rate is about 20 percent. The polymer foam is a microporous material having a polymer as a matrix and numerous bubbles therein, and is available in many kinds, and typical foam materials include polyurethane foam, polystyrene foam, and the like. Generally, the method of preparing the foaming material is classified into a physical foaming method and a chemical foaming method according to the manner of generating gas. Physical foaming is the formation of cells in a plastic matrix by a blowing agent changing physical state. During processing, or when the pressure is reduced or eliminated, the compressed gas expands, or the liquid evaporates and expands under heat, or the solid matter dissolved in the matrix sublimes under heat to produce gas, wherein the volatile liquid is the main foaming agent. Because the liquid evaporation is an endothermic process, the temperature of the foaming system is easy to control, the thermal degradation of the polymer matrix can be prevented, and thicker foaming parts can be prepared. The chemical foaming method is a method in which a polymer matrix is foamed by generating a gas by a chemical method, and a chemical foaming agent added to the matrix is heated to be decomposed and release the gas for foaming. Compared with a physical foaming method, the foam material prepared by a chemical foaming method has slightly higher cost and complex process, but the prepared product has better performance.

With the maturity of electronic information technology, 3D printing also comes along and is popularized in a large scale, opening the era of mold-free manufacturing. Journal of the academician of economics describes that digital manufacturing techniques, such as 3D printing, will alter the mode of production in the manufacturing industry and thus change the mode of operation of the industrial chain. According to the definition given by the american society for testing and materials international standards organization F42 technical committee for additive manufacturing: 3D printing is a process of manufacturing objects from layers of material connected together according to 3D model data. The core of the method is that a complex 3D entity of a part to be molded is converted into a simple 2D section combination through slicing processing, and the entity part is directly molded on 3D printing equipment according to a 3D computer-aided design model of the part. At present, 3D printing has been widely used in many fields, and with the development of this technology itself, its application field will be continuously expanded.

The 3D printing is used for preparing the foaming part, so that the development of a mold can be saved, the manufacturing cost is greatly reduced, and the method has stronger practical significance. At present, a foaming part is mainly prepared by fused deposition molding 3D printing. CN2018100218279 discloses a preparation method and application of a composition with micron-sized holes for fused deposition modeling 3D printing, wherein high polymer material particles are made into wires by a single-screw extruder, and then supercritical CO at or above critical pressure and critical temperature is adopted ₂ The fluid is immersed into the polymer base material by utilizing the characteristics of high density, low viscosity and large diffusion coefficient, and finally, the pressure is suddenly released, and micron-sized holes are formed in the polymer base material, so that a product with the multi-scale holes is prepared. CN201711281110X discloses a composition for fused deposition modeling 3D printer, preparation and application, which comprises three phases of high molecular polymer continuous phase, foaming agent phase and low melting point alloy phase, the composition is adopted to carry out fused deposition 3D printing to form a part, and the part is placed into a medium frequency electromagnetic induction furnace to be heated for 6-And (5) forming micron-sized pores in the part within 10 seconds to obtain the porous part. As can be seen from the prior art, most of the matrix for preparing foamed articles based on 3D printing is thermoplastic resin, which has relatively low strength and modulus.

Direct-write 3D printing (DIW) is a new 3D printing technology, and its principle is to build a pre-designed three-dimensional structure by extruding high-viscosity Ink material with shear thinning property from a printing nozzle and stacking the Ink layers. The DIW3D printing is used for preparing thermosetting or light-cured foaming parts, has innovative significance, and can further expand the application range of the foaming material.

Disclosure of Invention

In order to make up the defects of the prior art, the invention aims to provide a preparation method of a polymer matrix composite foamed part, which adopts the following technical scheme:

heating and uniformly mixing the prepolymer, a polar diluent, a photoinitiator, a thermal initiator, thermoplastic expanded microspheres, a surfactant and a viscosity regulator to obtain a mixture, putting the mixture into a direct-writing 3D printer, and printing and extruding; irradiating the extruded mixture by using a light source to perform photocuring reaction; and then putting the product into a microwave oven to carry out thermal curing reaction and simultaneously foam to obtain a foamed product.

Further, the heating temperature of the mixture is 70-90 ℃, and the stirring and mixing time is 20-30 min.

Furthermore, the temperature of the mixture is 40-50 ℃ during printing, the extrusion pressure is 0.05-0.4MPa, and the printing speed is 1-8 mm/s.

Further, the wavelength of the light source is 350-400 nm; the microwave treatment time is 20-50s, and the frequency of the microwave is 2000MHz-3000 GHz.

According to the embodiment of the invention, the prepolymer is one or more of epoxy acrylate, polyurethane acrylate and polyester acrylate.

According to the embodiment of the invention, the polar diluent is a polymer monomer and comprises one or more of 2-phenoxyethyl acrylate, 1, 6-hexanediol acrylate and isoborneol acrylate.

According to an embodiment of the present invention, the photoinitiator is a free radical photoinitiator comprising one or more of 2-hydroxy-2-methyl-1-phenyl propanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2- (4-morpholinyl) -1- [4- (methylthio) phenyl ] -1-propanone, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide.

According to the embodiment of the invention, the thermal initiator is one or more of dibenzoyl peroxide, di-tert-butyl peroxide and methyl ethyl ketone peroxide.

According to an embodiment of the present invention, the thermoplastic expanded microspheres have a pre-expansion particle size of 5-30 μm and an initial expansion temperature of 120 ℃.

According to an embodiment of the invention, the surfactant is an anionic surfactant, including stearic acid or sodium dodecylbenzene sulfonate.

According to the embodiment of the invention, the viscosity modifier is oxidized polyethylene wax, and the weight average molecular weight is 3000-1000.

According to the embodiment of the invention, after the photocuring reaction is carried out, completely immersing the 3D printed part into a DMF (dimethyl formamide) solution containing a thermoplastic polyurethane elastomer (TPU) for 5-10min, wherein the mass fraction of the TPU is controlled to be 8-14wt%, and wrapping the outer layer of the part with a TPU film, wherein the thickness of the film is 1-1.8 mm; then putting the workpiece into a microwave oven to carry out thermal curing reaction and simultaneously foam; and finally, mechanically stripping the TPU film on the outer layer to obtain a foamed product.

The invention also aims to provide a direct-writing 3D printing foaming part, which comprises the following components in parts by mass: comprises 65-82wt% of prepolymer, 12-20wt% of polar diluent, 0.6-2.5wt% of photoinitiator, 0.8-2.5wt% of thermal initiator, 1.5-4wt% of thermoplastic expanded microspheres, 2-4wt% of surfactant and 3-8wt% of viscosity regulator.

For example, the prepolymer may be 65 wt%, 70 wt%, 75 wt%, 76 wt%, 80 wt%, 82wt%, 12 wt%, 15 wt%, 18 wt%, 20wt%, and the photoinitiator may be 0.6 wt%, 0.8 wt%, 1 wt%, 1.4 wt%, 1.8 wt%, 2.2 wt%, 2.5 wt%; the thermal initiator may be 0.8 wt%, 1 wt%, 1.4 wt%, 1.8 wt%, 2.2 wt%, 2.5 wt%; the thermoplastic expanded microspheres may be 1.5 wt%, 2wt%, 2.5wt%, 3 wt%, 3.5 wt%, 4wt%, the surfactant may be 2wt%, 2.4 wt%, 3 wt%, 4wt%, the viscosity modifier may be 3 wt%, 4wt%, 5wt%, 6 wt%, 7 wt%, 8 wt%.

According to an embodiment of the invention, the viscosity of the part at room temperature is 450-700 cP; for example, 450cP, 550cP, 580cP, 700cP can be used.

The porosity of the foaming part prepared by the method is 3-12%, and the pore size is 10-80 μm.

The invention realizes secondary curing by adopting a light curing agent and a heat curing agent, firstly, a mixture is irradiated by ultraviolet light after coming out of a nozzle opening of a printer and then undergoes a light curing reaction to form a gel state, unreacted monomers and a small amount of prepolymer are still arranged in a workpiece, then, in the microwave treatment process, polar monomers are subjected to the action of microwave, the molecular orientation of the polar monomers changes along with a microwave field, a phenomenon similar to friction is generated, the polar monomers are rapidly heated and heated, so that a heat initiator is decomposed to further undergo a curing reaction, and simultaneously, thermoplastic expansion microspheres are initiated to undergo thermal expansion to form pores. According to the invention, the TPU flexible film is adopted to coat the 3D printed workpiece, so that the rapid expansion of the microspheres in the initial stage of microwave treatment is effectively inhibited, and meanwhile, the viscosity of the system is increased more and more due to the curing reaction of the resin in the later stage of microwave treatment, so that the expansion resistance of the microspheres is increased rapidly, and the two cooperate with each other to ensure the dimensional stability of the final workpiece.

The beneficial effects of the invention are as follows:

(1) according to the invention, an ultraviolet light source and microwaves are used as curing energy sources, and simultaneously material formula design is combined, so that resin is subjected to secondary curing, the mechanical property of a product is improved, in the microwave treatment process, a polar monomer is rapidly heated and heated under the action of microwaves, thermal expansion and curing reaction of thermoplastic expansion microspheres occur simultaneously, pores are formed and shaped, and the 3D printing foaming product with excellent performance is prepared.

(2) According to the invention, the TPU flexible film is adopted to coat the 3D printed workpiece, so that the dimensional stability of the workpiece is effectively ensured.

Drawings

FIG. 1 is an SEM photograph of example 2;

FIG. 2 is an SEM photograph of example 4.

Detailed Description

The compounds of the general formula and the preparation and use thereof according to the present invention will be described in further detail with reference to the following examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

Example 1

A polymer-based composite material foamed part comprises the following components in parts by mass: the epoxy resin composition comprises 75 wt% of epoxy acrylate, 12 wt% of 2-phenoxyethyl acrylate, 0.8 wt% of 2-hydroxy-2-methyl-1-phenyl acetone, 0.8 wt% of dibenzoyl peroxide, 2wt% of thermoplastic expanded microspheres, 2.4 wt% of stearic acid and 7 wt% of oxidized polyethylene wax with the weight-average molecular weight of 1000, wherein the viscosity of the product at room temperature is 550 cP. The preparation method of the product comprises the following steps: all the components are stirred and mixed for 30min at 70 ℃, and naturally cooled to room temperature to prepare a mixture. The particle size of the thermoplastic expanded microspheres before expansion is 10 mu m, and the initial expansion temperature is 120 ℃.

And (2) placing the mixture into a direct-writing 3D printer for 3D printing, wherein the temperature of the mixture is 40 ℃, the extrusion pressure is 0.1MPa, the printing speed is 1.5mm/s, irradiating the extruded mixture by adopting a light source with the wavelength of 350nm to perform photocuring reaction, preparing a sample, and then placing the sample into a microwave oven for processing for 30s, wherein the microwave frequency is 5000MHz, thus preparing a foamed part.

Example 2

A polymer-based composite material foamed part comprises the following components in parts by mass: the epoxy resin composition comprises 76 wt% of epoxy acrylate, 12 wt% of 2-phenoxyethyl acrylate, 0.8 wt% of 2-hydroxy-2-methyl-1-phenyl acetone, 0.8 wt% of dibenzoyl peroxide, 4wt% of thermoplastic expanded microspheres, 2.4 wt% of stearic acid, and 4wt% of oxidized polyethylene wax with the weight-average molecular weight of 1000, wherein the viscosity of the mixture at room temperature is 580cP, and the preparation method of the mixture comprises the following steps: mixing all the components at a certain ratio, stirring and mixing at 70 deg.C for 30min, and naturally cooling to room temperature to obtain mixture.

Placing the mixture into a direct-writing 3D printer for 3D printing, wherein the temperature of the mixture is 40 ℃, the extrusion pressure is 0.15MPa, the printing speed is 1.5mm/s, and irradiating the extruded mixture by adopting a light source with the wavelength of 350nm to perform photocuring reaction to prepare a sample; and then, putting the sample into a microwave oven for processing for 30s, wherein the microwave frequency is 5000MHz, and preparing a product.

Example 3

The mixture of example 1 was placed in a direct-write 3D printer for 3D printing at a temperature of 40 ℃, an extrusion pressure of 0.1MPa, and a printing speed of 1.5mm/s, and the extruded mixture was irradiated with a light source having a wavelength of 350nm to undergo a photocuring reaction, thereby preparing a sample. And then, putting the sample into a microwave oven for processing for 50s, wherein the microwave frequency is 5000MHz, and preparing a product.

Example 4

The mixture of example 1 was placed in a direct-write 3D printer for 3D printing at a temperature of 40 c and an extrusion pressure of 0.1MPa and a printing speed of 1.5mm/s, and the extruded mixture was irradiated with a light source having a wavelength of 350nm to cause a photocuring reaction, thereby preparing a sample. And completely immersing the 3D printed sample into a DMF (dimethyl formamide) solution containing TPU (thermoplastic polyurethane) for 5min, wherein the mass fraction of the TPU is controlled to be 8wt%, and coating a layer of TPU film on the outer layer of the workpiece, wherein the thickness of the film is 1 mm. Then the sample is put into a microwave oven for processing for 30s, and the microwave frequency is 5000 MHz. Finally, mechanically stripping the TPU film to obtain a foamed part

Example 5

The mixture of example 1 was placed in a direct-write 3D printer for 3D printing at a temperature of 40 ℃, an extrusion pressure of 0.1MPa, and a printing speed of 1.5mm/s, and the extruded mixture was irradiated with a light source having a wavelength of 350nm to undergo a photocuring reaction, thereby preparing a sample. And completely immersing the 3D printed sample into a DMF solution containing TPU for 5min, wherein the mass fraction of the TPU is controlled at 12 wt%, and a layer of TPU film is wrapped on the outer layer of the workpiece, and the thickness of the film is 1.6 mm. Then the sample is put into a microwave oven to be processed for 30s, and the microwave frequency is 5000 MHz. Finally, mechanically stripping the TPU film to obtain a foamed part

Comparative example 1

Placing the mixture obtained in the example 1 into a direct-writing 3D printer for 3D printing, wherein the temperature of the mixture is 40 ℃, the extrusion pressure is 0.1MPa, the printing speed is 1.5mm/s, and irradiating the extruded mixture by using a light source with the wavelength of 350nm to perform photocuring reaction to obtain a foamed part

Comparative example 2

A polymer-based composite material foamed part comprises the following components in parts by mass: the epoxy acrylate-modified epoxy resin composite material comprises 75 wt% of epoxy acrylate, 12 wt% of 2-phenoxyethyl acrylate, 0.8 wt% of 2-hydroxy-2-methyl-1-phenyl acetone, 0.8 wt% of azobisisobutyronitrile, 2wt% of thermoplastic expanded microspheres, 2.4 wt% of stearic acid and 7 wt% of oxidized polyethylene wax with the weight-average molecular weight of 1000, wherein the viscosity of the mixture at room temperature is 530 cP. The preparation method of the mixture comprises the following steps: all the components are stirred and mixed for 30min at 70 ℃, and naturally cooled to room temperature to prepare a mixture.

And (3) putting the workpiece into a direct-writing 3D printer for 3D printing, wherein the temperature of a mixture is 40 ℃, the extrusion pressure is 0.1MPa, the printing speed is 1.5mm/s, and a light source with the wavelength of 350nm is adopted to irradiate the extruded mixture to perform photocuring reaction to prepare a sample. And then, putting the sample into a microwave oven for processing for 30s, wherein the microwave frequency is 5000MHz, and obtaining a foaming part.

Comparative example 3

A polymer-based composite material foamed part comprises the following components in parts by mass: comprises 85 weight percent of epoxy acrylate, 4 weight percent of 2-phenoxyethyl acrylate, 0.8 weight percent of 2-hydroxy-2-methyl-1-phenyl acetone, 0.8 weight percent of dibenzoyl peroxide, 2 weight percent of thermoplastic expanded microspheres, 2.4 weight percent of stearic acid and 7 weight percent of oxidized polyethylene wax with the weight-average molecular weight of 1000 to obtain a mixture, and the viscosity of the mixture at room temperature is 1250 cP.

And (3) placing the mixture into a direct-writing 3D printer for 3D printing, wherein the temperature of the mixture is 40 ℃, the extrusion pressure is 0.1MPa, the printing speed is 1.5mm/s, and irradiating the extruded mixture by adopting a light source with the wavelength of 350nm to perform photocuring reaction to prepare a sample. And then, putting the sample into a microwave oven for processing for 30s, wherein the microwave frequency is 5000MHz, and obtaining a foaming part.

Application example

The porosity of the test specimen is measured by a density method, and the tensile property is measured according to ISO 527-5A. Rectangular parallelepiped test specimens of 50mm by 5mm were 3D printed, the percentage dimensional deviation of the long side was measured, the dimensional stability of the test specimens was characterized, and the test results are shown in table 1.

TABLE 1 test data for the examples and comparative samples

As can be seen from the above table, in comparative example 1 and comparative example 1, the strength and porosity of the sample are improved when the sample is thermally cured by microwave irradiation and foamed; comparing example 1 with comparative example 2, the secondary curing could not be achieved by changing the thermal initiator, and the strength of the sample was low; comparing examples 1 and 2, it can be seen that as the content of the thermoplastic expandable microspheres increases, the porosity of the sample increases greatly; comparing examples 1 and 3, it can be seen that the strength and porosity of the sample are further improved as the microwave irradiation time is prolonged; comparing examples 1 and 4, it can be seen that the foaming behavior is somewhat suppressed after the sample is coated with the TPU film, resulting in a slight decrease in porosity but a substantial decrease in dimensional deviation; comparing examples 4 and 5, it can be seen that the dimensional stability is further improved with increasing thickness of the TPU coating film. Analysis of the data from example 1 and comparative example 3 shows that the viscosity of the material is so high that 3D printing cannot be formed without the use of the components of the present application.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a polymer matrix composite foamed part is characterized by comprising the following steps:

heating and uniformly mixing the prepolymer, a polar diluent, a photoinitiator, a thermal initiator, thermoplastic expanded microspheres, a surfactant and a viscosity regulator to obtain a mixture, putting the mixture into a direct-writing 3D printer, printing and extruding, and irradiating the extruded mixture by adopting a light source to perform photocuring reaction; then putting the workpiece into a microwave oven to carry out thermal curing reaction and simultaneously foam to obtain a foamed workpiece;

the wavelength of the light source is 350-400 nm; the microwave treatment time is 20-50s, and the frequency of the microwave is 2000MHz-3000 GHz;

the thermal initiator is one or more of dibenzoyl peroxide, di-tert-butyl peroxide and methyl ethyl ketone peroxide;

the particle size of the thermoplastic expanded microspheres before expansion is 5-30 mu m, and the initial expansion temperature is 120 ℃;

the article comprises, by mass: 65-82wt% of prepolymer, 12-20wt% of polar diluent, 0.6-2.5wt% of photoinitiator, 0.8-2.5wt% of thermal initiator, 1.5-4wt% of thermoplastic expanded microsphere, 2-4wt% of surfactant and 3-8wt% of viscosity regulator;

the viscosity of the article at room temperature is 450-700 cP.

2. The method of claim 1, wherein the mixture is heated at a temperature of 70-90 ℃ and stirred for a mixing time of 20-30 min.

3. The process according to claim 1, wherein the mixture temperature at printing is 40 to 50 ℃, the extrusion pressure is 0.05 to 0.4MPa, and the printing speed is 1 to 8 mm/s.

4. The preparation method of claim 1, wherein the prepolymer is one or more of epoxy acrylate, urethane acrylate and polyester acrylate;

the polar diluent is a polymer monomer and comprises one or more of 2-phenoxyethyl acrylate, 1, 6-hexanediol acrylate and isoborneol acrylate;

the photoinitiator is a free radical photoinitiator and comprises one or more of 2-hydroxy-2-methyl-1-phenyl acetone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2- (4-morpholinyl) -1- [4- (methylthio) phenyl ] -1-acetone and 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide;

the surfactant is an anionic surfactant and comprises stearic acid or sodium dodecyl benzene sulfonate.

5. The preparation method as claimed in claim 1, wherein the viscosity modifier is oxidized polyethylene wax having a weight average molecular weight of 1000-3000.

6. The preparation method according to claim 1, wherein after the photocuring reaction, the 3D-printed article is completely immersed in a DMF solution containing a thermoplastic polyurethane elastomer for 5-10min, wherein the mass fraction of the thermoplastic polyurethane elastomer is controlled to be 8-14wt%, and the article is wrapped with a thermoplastic polyurethane elastomer film having a film thickness of 1-1.8 mm; then putting the workpiece into a microwave oven to carry out thermal curing reaction and simultaneously foam; and finally, mechanically stripping the thermoplastic polyurethane elastomer film on the outer layer to obtain a foamed part.