阅读说明：本技术 用于fdm法打印的可控轻量化发泡材料及其制备方法与应用 (Controllable lightweight foam material for FDM printing and preparation method and application thereof ) 是由 杨义浒 胡浩 陈锐 刘浦 于 2021-05-06 设计创作，主要内容包括：本发明公开了一种用于FDM法打印的可控轻量化发泡材料及其制备方法与应用,属于3D打印技术领域。该制备方法包括如下步骤：1)制备颗粒物A；2)制备颗粒物B：其中,双螺杆挤出机加工温度为60～140℃,发泡剂占颗粒物B质量的30～50％；且侧料斗下料口与模头之间距离为螺杆长度的1/10～1/2；3)拉丝处理：取步骤1)的颗粒物A、步骤2)的所述颗粒物B混匀,通过单螺杆挤出机拉丝处理,即用于FDM法打印的可控轻量化发泡丝线。该发泡材料制备发泡制品时,不仅发泡工艺容易控制,而且发泡倍率较高,通过调节FDM打印机挤出倍率或/和流量在打印相同大小模型时可减少制品重量50％以上。(The invention discloses a controllable lightweight foam material for FDM printing and a preparation method and application thereof, and belongs to the technical field of 3D printing. The preparation method comprises the following steps: 1) preparing particles A; 2) preparing particles B: wherein the processing temperature of the double-screw extruder is 60-140 ℃, and the foaming agent accounts for 30-50% of the mass of the particles B; and the distance between the feed opening of the side hopper and the die head is 1/10-1/2 of the length of the screw; 3) wire drawing treatment: uniformly mixing the particulate matter A obtained in the step 1) and the particulate matter B obtained in the step 2), and performing wire drawing treatment through a single-screw extruder, namely, a controllable lightweight foaming silk thread for FDM printing. When the foaming material is used for preparing a foaming product, the foaming process is easy to control, the foaming multiplying power is high, and the weight of the product can be reduced by more than 50% by adjusting the extrusion multiplying power or/and the flow of an FDM printer when models with the same size are printed.)

1. A preparation method of a controllable lightweight foam material for FDM printing is characterized by comprising the following steps:

1) preparing a particle A: uniformly mixing polylactic acid and other formula components, mixing and plasticizing the mixture by using a double-screw extruder, and granulating to obtain a particulate matter A, wherein the processing temperature of the double-screw extruder is 180-200 ℃, and the polylactic acid accounts for 90-98% of the mass of the particulate matter A;

2) preparing particles B: feeding a toughening agent through a main hopper of the double-screw extruder, feeding a foaming agent through a side hopper, mixing and plasticizing, and granulating to obtain a particulate matter B, wherein the processing temperature of the double-screw extruder is 60-140 ℃, and the foaming agent accounts for 30-50% of the mass of the particulate matter B; and the distance between the feed opening of the side hopper and the die head is 1/10-1/2 of the length of the screw;

3) wire drawing treatment: uniformly mixing the particulate matter A obtained in the step 1) and the particulate matter B obtained in the step 2) according to the mass ratio of (7:3) - (8:2), and performing wire drawing treatment by using a single-screw extruder to obtain the controllable light-weight foaming silk thread with the diameter of 1.75mm for FDM printing.

2. The method for preparing the controllable lightweight foaming material for FDM printing according to claim 1, wherein the foaming agent starts foaming at a temperature of 200-240 ℃ during FDM printing.

3. The method for preparing the controllable light-weight foaming material for FDM printing according to claim 2, wherein the foaming agent is one or two or three of azodicarbonamide, p-toluenesulfonyl semicarbazide or expanded microspheres.

4. The foam material prepared by the preparation method of claim 1 is characterized by comprising the following formula components in percentage by mass:

65-80% of polylactic acid, 0.2-1% of plasticizer, 0.2-0.5% of cross-linking agent, 0.2-5% of chain extender, 5-15% of flexibilizer, 0.2-1% of lubricant, 0.2-1% of antioxidant, 1-5% of nucleating agent and 5-15% of foaming agent.

5. The foam material as claimed in claim 4, wherein the foaming agent is one or two or three of azodicarbonamide, p-toluenesulfonyl semicarbazide or expanded microspheres.

6. The foam material as claimed in claim 4, wherein the melting point of the toughening agent is 70-130 ℃.

7. The foam material of claim 6, wherein the toughening agent is at least one of a polylactic acid-based thermoplastic polyurethane elastomer, a methyl acrylate copolymer, an ethylene-octene high polymer or an ethylene-vinyl acetate copolymer.

8. The foam material according to any one of claims 4 to 6, wherein the plasticizer is one or two or more of acetyl tributyl citrate, epoxidized soybean oil, a propylene oxide condensate and dibutyl phthalate.

9. The foam material as claimed in any one of claims 4 to 6, wherein the cross-linking agent is at least one of dibenzoyl peroxide, dicumyl peroxide or di-tert-butylperoxyisopropyl benzene; the chain extender is at least one of styrene-glycidyl methacrylate copolymer, diisocyanate, phosphite ester, dianhydride or diepoxy compound.

10. The foaming material prepared by the preparation method according to claim 1 is used for FDM (fused deposition modeling) method printing of 3D products, wherein the extrusion rate or/and flow of an FDM printer are/is adjusted to obtain printed products with different densities and sizes, and the printing temperature is set to be 190-270 ℃.

Technical Field

The invention relates to a 3D printing material, belongs to the technical field of 3D printing, and particularly relates to a controllable lightweight foaming material for FDM printing, and a preparation method and application thereof.

Background

In recent decades, as a new technology in the field of rapid prototyping, 3D printing technology has been developed very rapidly and is currently applied in the fields of aerospace, biomedicine, national defense and military industry, engineering education, new product development, and the like. The 3D printing technology is mainly classified into a fused deposition modeling technology (FDM method), a stereolithography (SLA method), a solvent cast molding (SC-3DP method), and a selective laser sintering molding technology (SLS method) according to the core of the manufacturing plastic manufacturing process. The FDM is the fastest in development and wide in application, and the FDM method is clean and safe in operating environment, simple in process and easy to operate.

Polylactic acid (PLA) material is the most commonly used material when FDM prints at present, it is very easy to print, it is difficult to warp or nozzle block to print, compared with thermoplastic elastomer, it is also difficult to shrink when printing, another advantage of PLA material is that it provides the high quality surface detail of 3D printing, other materials are easy to produce wire drawing or spot, different from another popular 3D printing material ABS, PLA material can not give off unpleasant smell when extruding, typical PLA material is non-toxic and biodegradable, make it the ideal material of environment-friendly 3D printer user.

The foaming material is a material with a porous structure generated by gasification or expansion of a foaming agent in the material, the density and the dosage of the material can be reduced on the premise of less loss of the mechanical property of the material, and the requirements of light weight, high strength and functionality of the material are met. At present, the preparation method of the foaming material is basically concentrated in the traditional manufacturing field, for example, the foaming technology of the polymer prepared by the supercritical fluid and the secondary die opening method have high die opening cost and long development period. The method promotes the development of a foamable 3D printing material, and combines the preparation method with a rapid forming technology, so that the development speed of porous products is greatly improved, and the support force on individualized products is greatly increased.

According to the sequence of foaming and 3D printing, the foaming products applied to 3D printing are mainly divided into the following categories:

1. and performing foaming treatment before 3D printing, and then performing product molding by using a 3D printer. For example, the patent document of the chinese invention patent (application publication No. CN111154135A, application publication date: 2020-05-15) discloses a 3D printed foamed product and a process for preparing the same, wherein the process comprises the steps of mixing a first polymer resin with a second polymer resin powder to obtain a powder to be foamed, subjecting the powder to be foamed to supercritical foaming in a supercritical fluid to obtain a foamed powder in which the first polymer resin is wrapped by the second polymer resin, and then subjecting the foamed powder to selective laser sintering to obtain the foamed product, which is not suitable for FDM printing.

2. And performing foaming treatment after 3D printing to obtain the product. For example, the Chinese invention patent (application publication No. CN111154135A, application publication No. 2017-03-15) discloses a method and a device for producing a foamed product by combining 3D printing. According to the method, a three-dimensional model is printed according to the needs of a product, then the three-dimensional model permeates in a supercritical permeation unit, and then the three-dimensional model is foamed by water vapor in a foaming box to obtain a foamed product, but the finally obtained foamed product is rough in appearance and cannot fully utilize the advantage of 3D printing.

3. Directly foaming to obtain the product during 3D printing. For example, Chinese invention patent (application publication No. CN107254151A, application publication date: 2017-10-17) discloses a microcellular foamed 3D printing polymer consumable, a preparation method and a production device thereof, wherein a specific compound foaming agent and a polymer matrix are selected to prepare the 3D printing polymer consumable, and the polymer consumable is foamed simultaneously through an FDM printer to obtain a light FDM mode 3D printing consumable, but the foaming multiplying power is very small, and the quality of a printed product is reduced by more than 10% under the same printing condition.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a controllable lightweight foam material for FDM printing, and a preparation method and application thereof. When the foaming material is used for preparing a foaming product, the foaming process is easy to control, the foaming multiplying power is higher, and the weight of the product can be reduced by more than 50% when the models with the same size are printed.

In order to realize the technical purpose, the invention discloses a preparation method of a controllable lightweight foam material for FDM printing, which comprises the following steps:

1) preparing a particle A: uniformly mixing polylactic acid and other formula components, mixing and plasticizing the mixture by using a double-screw extruder, and granulating to obtain a particulate matter A, wherein the processing temperature of the double-screw extruder is 180-200 ℃, and the polylactic acid accounts for 90-98% of the mass of the particulate matter A;

2) preparing particles B: feeding a toughening agent through a main hopper of the double-screw extruder, feeding a foaming agent through a side hopper, mixing and plasticizing, and granulating to obtain a particulate matter B, wherein the processing temperature of the double-screw extruder is 60-140 ℃, and the foaming agent accounts for 30-50% of the mass of the particulate matter B; and the distance between the feed opening of the side hopper and the die head is 1/10-1/2 of the length of the screw; according to the invention, the foaming agent is selected to feed and discharge from the middle section or the tail end of the screw from the side, the method is favorable for keeping the foaming rate of the foaming agent during subsequent 3D printing without foaming during granulation processing, and the toughening agent is discharged from the main hopper and is not discharged from the side hopper together with the foaming agent, so that the plasticizing and mixing of the toughening agent can be enhanced.

3) Wire drawing treatment: uniformly mixing the particulate matter A obtained in the step 1) and the particulate matter B obtained in the step 2) according to the mass ratio of (7:3) - (8:2), and performing wire drawing treatment by using a single-screw extruder to obtain the controllable light-weight foaming silk thread with the diameter of 1.75mm for FDM printing.

Furthermore, the foaming agent starts to foam at the temperature of 200-240 ℃ in the FDM printing process.

Further, the foaming agent is one or two or three of azodicarbonamide, p-toluenesulfonyl semicarbazide or expanded microspheres.

One of the purposes of the technical scheme disclosed by the invention is to disclose the foaming material prepared by the preparation method, which comprises the following components in percentage by mass:

65-80% of polylactic acid, 0.2-1% of plasticizer, 0.2-0.5% of cross-linking agent, 0.2-5% of chain extender, 5-15% of flexibilizer, 0.2-1% of lubricant, 0.2-1% of antioxidant, 1-5% of nucleating agent and 5-15% of foaming agent.

Further, the foaming agent is one or two or three of azodicarbonamide, p-toluenesulfonyl semicarbazide or expanded microspheres.

Further, the melting point of the toughening agent is 60-140 ℃.

Further, the toughening agent is at least one of polylactic acid-based thermoplastic polyurethane elastomer, methyl acrylate copolymer, ethylene-octene high polymer or ethylene-vinyl acetate copolymer.

Further, the plasticizer is one or two or more of acetyl tributyl citrate, epoxidized soybean oil, a propylene oxide condensate and dibutyl phthalate.

Further, the crosslinking agent is at least one of dibenzoyl peroxide, dicumyl peroxide or di-tert-butylperoxyisopropyl benzene; the chain extender is at least one of styrene-glycidyl methacrylate copolymer, diisocyanate, phosphite ester, dianhydride or diepoxy compound.

The other purpose of the technical scheme disclosed by the invention is to provide the foaming material prepared by the preparation method for printing a 3D product by an FDM method, and obtain printed products with different densities and sizes by adjusting the extrusion multiplying power of an FDM printer, wherein the printing temperature is set to be 190-270 ℃.

Specifically, the extrusion rate is 30-100%.

Preferably, the printing temperature is 250 ℃.

Has the advantages that:

1. the invention provides a method for directly printing a lightweight product by using an FDM printer, and the method has the advantages that the foaming ratio is high and can exceed 2.5 times, and the weight of the product can be reduced by over 50% when a model with the same size is printed.

2. The material designed by the invention is simple and convenient in production process, is convenient and flexible to use in FDM printing, can obtain PLA products with different densities and sizes by controlling the extrusion multiplying power and/or extrusion flow of the printer according to the requirements of the products, has the printing temperature of 190-270 ℃, can foam when printing when exceeding the foaming temperature, can adjust the extrusion multiplying power and/or extrusion flow of the 3D printer when printing, can control the size and weight of the printed products under the same condition, has higher impact strength than common PLA, and provides a method for printing lightweight models and parts with different sizes.

3. The processing temperature in the step (2) in the preparation process is 60-140 ℃, the processing temperature far lower than the initial foaming temperature of the foaming agent is used, and meanwhile, the foaming agent is fed and discharged at the middle section or the tail end of the screw rod, so that the method is favorable for keeping the high foaming rate of the foaming agent during subsequent 3D printing without foaming during processing, and the toughening agent with low melting point can play a toughening effect and can also be used as a foaming agent carrier, thereby being favorable for the good dispersion of the foaming agent in polylactic acid.

Drawings

FIG. 1 is a schematic view of a part of a processing apparatus;

wherein, the numbers in the drawings are as follows:

main hopper 1, side hopper 2, motor 3, die head 4.

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. It should be understood that the described embodiments are only some of the embodiments of the present invention, and they are not to be construed as limiting the invention, but merely as exemplifications. 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 foam material of the embodiment comprises the following components in percentage by mass:

the preparation method adopting the components comprises the following steps:

1) preparing a particle A: and putting 72 parts of polylactic acid, 1 part of plasticizer ATBC, 0.2 part of cross-linking agent DCP, 3 parts of chain extender ADR, 0.5 part of lubricant silicone powder, 0.3 part of antioxidant 1010 and 3 parts of nucleating agent talcum powder into a high-speed mixer, mixing for 10min, melting, blending and extruding by a double-screw extruder after uniform mixing, and performing water cooling and grain cutting to obtain the particles A. Drying the obtained granules A in a 65 ℃ vacuum drying oven for 4 hours, wherein the moisture content is lower than 0.2%, the processing temperature is 200 ℃, the temperatures of 1-7 areas of an extruder are respectively 160, 180, 190, 200, 200, 190 and 180, the temperature unit is the temperature, and the rotating speed of a main engine is 200 rpm.

2) Preparing particles B: and (2) putting 12 parts of a toughening agent PLA-TPU into a main hopper 1 shown in the figure 1, putting 8 parts of expanded microspheres into a side hopper 2, performing melt blending extrusion through a double-screw extruder, and performing water cooling and grain cutting to obtain particles B. Drying the particles B in a 65 ℃ vacuum drying oven for 4 hours, wherein the measured moisture content is lower than 0.2%, the processing temperature is 130 ℃, the temperatures of 1-7 areas of the extruder are respectively 100, 110, 120, 130, 130, 120 and 120, the temperature unit is that the rotating speed of a main machine is 50rpm, and the distance between a side hopper feed opening and the die head 4 is 1/5 of the length of a screw rod; the motor 3 is used for providing power;

3) wire drawing treatment: mixing the particulate matter A in the step 1) and the particulate matter B in the step 2) at a high speed for 5-10 min according to a mass ratio of 8:2, drawing a wire into a filament with the diameter of 1.75mm through a single-screw extruder, and winding the filament at the tail end by using a 3D printing wire coil; the extrusion temperature of the single-screw extruder is 180 ℃, the temperatures of the 1-5 zones are respectively 160, 175, 180, 180 and 170, the temperature unit is that, and the rotating speed of the main machine is 30 rpm.

4) Preparing a 3D printed article: the drawn silk threads are sent into an FDM 3D printer to be printed, the printed silk threads are rectangular blocks, 15mm x 10mm, the filling rate is 100%, the printing speed is 40mm/s, the printing temperature is set to be 190 ℃ and 250 ℃, when the silk threads are printed at 250 ℃, the extrusion flow rate is gradually reduced according to the change of the density, the change of the volume size of the printed silk threads is observed, the density is measured, and the size of the printed silk threads is controlled by adjusting the extrusion multiplying power (extrusion flow rate) of the 3D printer. The properties of the material prepared in this example are shown in tables 1 and 2.

Example 2

The foam material of the embodiment comprises the following components in percentage by mass:

the preparation method adopting the components comprises the following steps:

1) preparing a particle A: 70 parts of polylactic acid, 1 part of plasticizer ATBC, 0.2 part of cross-linking agent DCP, 3 parts of chain extender HDI, 0.5 part of lubricant silicone powder, 0.3 part of antioxidant 1010 and 5 parts of nucleating agent talcum powder are put into a high-speed mixer to be mixed for 10min, and after being uniformly mixed, the materials are melted, blended and extruded by a double-screw extruder, and the particles A are obtained by water cooling and grain cutting. Drying the obtained granules A in a 65 ℃ vacuum drying oven for 4 hours, wherein the moisture content is lower than 0.2%, the processing temperature is 200 ℃, the temperatures of 1-7 areas of an extruder are respectively 160, 180, 190, 200, 200, 190 and 180, the temperature unit is the temperature, and the rotating speed of a main engine is 200 rpm.

2) Preparing particles B: and (2) putting 12 parts of toughening agent EVA into a main feeder, putting 6 parts of foaming agent p-toluenesulfonyl semicarbazide into a side feeder, carrying out melt blending extrusion through a double-screw extruder, and carrying out water cooling and grain cutting to obtain particles B. Drying the granules B in a 65 ℃ vacuum drying oven for 4 hours, wherein the measured moisture content is lower than 0.2%, the processing temperature is 130 ℃, the temperatures of 1-7 areas of the extruder are respectively 100, 110, 120, 130, 130, 120 and 120, the temperature unit is that the rotating speed of a main machine is 50rpm, and the distance between a side feeding and discharging opening and a die head is 1/5 of the length of a screw;

3) wire drawing treatment: mixing the particulate matter A in the step 1) and the particulate matter B in the step 2) at a high speed for 5-10 min according to a mass ratio of 8:2, drawing a wire into a filament with the diameter of 1.75mm through a single-screw extruder, and winding the filament at the tail end by using a 3D printing wire coil; the extrusion temperature of the single-screw extruder is 180 ℃, the temperatures of the 1-5 zones are respectively 160, 175, 180, 180 and 170, the temperature unit is that, and the rotating speed of the main machine is 30 rpm.

4) Preparing a 3D printed article: the drawn silk threads are sent into an FDM 3D printer to be printed, the printed silk threads are rectangular blocks, 15mm x 10mm, the filling rate is 100%, the printing speed is 40mm/s, the printing temperature is set to be 190 ℃ and 250 ℃, when the silk threads are printed at 250 ℃, the extrusion flow rate is gradually reduced according to the change of the density, the change of the volume size of the printed silk threads is observed, the density is measured, and the size of the printed silk threads is controlled by adjusting the extrusion multiplying power (extrusion flow rate) of the 3D printer. The properties of the material prepared in this example are shown in tables 1 and 2.

Example 3

The foam material of the embodiment comprises the following components in percentage by mass:

the rest of the procedure remained the same as in example 1.

Example 4

The foaming agent in the components of the foaming material of the embodiment is a mixture of azodicarbonamide and p-toluenesulfonyl semicarbazide in a mass ratio of 1:1, and the rest is the same as that in the embodiment 1.

Example 5

The foaming agent in the components of the foaming material of the embodiment is a mixture of azodicarbonamide, p-toluenesulfonyl semicarbazide and expanded microspheres in a mass ratio of 1:1:1, and the rest is the same as that in the embodiment 1.

Example 6

The toughening agent in the components of the foam material of this example is a methyl acrylate copolymer, and the rest is the same as that in example 1.

Example 7

The toughening agent in the component of the foam material of this example is ethylene-vinyl acetate copolymer (EVA), and the rest is the same as that in example 1.

Comparative example 1

The difference between the comparative example and the example 1 is that the toughening agent PLA-TPU and the foaming agent expanded microspheres in the step 2) are stirred according to the mixture ratio and then are discharged through the main feeding hopper, and the side feeding hopper does not discharge.

Comparative example 2

The comparative example is different from example 1 only in that after all the raw materials in step (1) and step (2) are proportioned and stirred and granulated by the process of step (1), the granules are drawn into filaments by the process of step (3) without step (2).

The printed test squares of the above examples and comparative examples, having dimensions of 15mm x 10mm, were evaluated using a classical FDM 3D printed test model, with different printing temperatures and extrusion flows, their printed shape size variations and the density of the 3D printed article, see table 1: wherein the extrusion flow rate comprises 30% to 100%, specifically 30%, 40%, 45%, 50%, 55%, 60%, 80%, 90% and 100%.

Table 13D density of printed articles at different printing temperatures and extrusion flows

The above-mentioned printed products were printed to prepare notched specimens (type A notches) of 80 mm. times.10 mm. times.4 mm, and the notched specimens were tested for notched impact properties in accordance with ISO Standard 179, the impact properties being shown in Table 2:

TABLE 2 list of impact properties

As can be seen from table 1, when the same model is printed in 3D, the printing temperature is 250 ℃, and the foaming temperature is exceeded, the product is deformed due to foaming expansion during printing, and the density is reduced.

As is clear from tables 1 and 2, the initial density of example 1 was 1.19g/cm³After the temperature is raised to 250 ℃, the foaming volume expands to deform, the volume expansion can be reduced by reducing the extrusion flow, and the density can be reduced to 0.485g/cm under the condition that the shape and the size can be basically kept unchanged when the extrusion flow is 40 percent³While comparative example 1 has a density of 0.68g/cm at the same temperature of 250 ℃ while keeping the shape and size substantially unchanged³Comparative example 2 the density at which the shape and size were kept substantially constant was 1.08g/cm³In example 1, the weight is lighter with the shape and size kept basically unchanged, the notch impact strength is slightly better than that of the comparative example, and in other examples, a light product with the shape and size basically unchanged can be obtained by reducing the extrusion flow, and detailed description is omitted.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.