Water-based binder for stainless steel bonding and spraying additive manufacturing and preparation method of water-based binder

Abstract

The invention discloses a water-based binder for stainless steel bonding spraying additive manufacturing and a preparation method. The binder comprises the following components in percentage by mass: 80 to 88 weight percent of deionized water, 8 to 10 weight percent of polyvinylpyrrolidone, 2 to 5 weight percent of propylene glycol, 0.2 to 1.0 weight percent of lauryl sodium sulfate, 1 to 3 weight percent of polyethylene glycol and 0.05 to 0.2 weight percent of antibacterial preservative. The preparation method comprises the following steps: stepwise dissolving (firstly dissolving PVP at a high temperature and a high speed, and then adding small molecule components at a low temperature and a low speed), dynamically dropwise adding an SDS solution (synchronously monitoring the pH value to 6.5-7.5), stirring at a gradient speed reduction (800-300rpm), and standing for defoaming. According to the binder, through a PVP thickening / SDS tension reduction / polyol synergy system, balance regulation and control of the viscosity of 8-12 mPa.s and the surface tension of 33-37 mN / m are achieved, and the requirement for spraying of a Piezo spray head is met; the weight loss at 400 DEG C is not less than 95%, and the residual carbon rate at 800 The cleanliness of the sintered part is guaranteed; no flocculation is generated after 6 months of storage in a dark place at 25 DEG C, and the environment-friendly effect is achieved. The problems that a traditional binder is poor in wettability, high in plugging risk, large in degreasing residue and unstable in storage are solved, and the green body strength and the sintering density are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of additive manufacturing, more particularly, relates to a water-based binder for stainless steel binder jetting additive manufacturing and a preparation method. BACKGROUND

[0002] Metal binder jetting (BJ) is a typical heat-free additive manufacturing technology, which is particularly suitable for forming metal powders such as stainless steel. It forms a "green body" by selectively jetting a binder on a powder bed to bind the powder, and obtains a final metal product after debinding and sintering. This process has the advantages of no support structure and high printing efficiency, and is widely used in the fields of aviation, medical treatment, molds, etc. in recent years. In this forming process, the performance of the binder has a decisive influence on the printing quality, the green body density, the dimensional accuracy and the subsequent sintering behavior. Among them, the surface tension and viscosity of the binder are the key parameters, which directly affect the jetting behavior of the nozzle and the distribution of powder wetting.

[0003] The commonly used binders on the market at present mainly use water or alcohol as the solvent, supplemented by high molecular polymers such as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as the main binder matrix, and adjust the rheological properties and spreading properties by adding surfactants, plasticizers, etc. However, the traditional binder has the following problems: high or low viscosity will cause nozzle blockage or unclear forming boundary during printing; improper adjustment of surface tension will cause insufficient powder wetting and uneven distribution of the bonding area; unreasonable control of solid content will affect the green body strength and debinding behavior; certain additives may react with stainless steel powder, which may cause sintering defects; and some water-based systems have poor wettability and large pores between the formed particles, resulting in insufficient green body density and strength, etc. Patent CN114250049A discloses a kind of ultra-low viscosity binder for metal 3DP printing process and its preparation method, the mass percentage components of the binder are: binder base 3-20%, diluent 75-92.5%, amphiphilic adhesion aid 0.5-3.0%, humectant 3-12%, and flow aid 1-5%; the amphiphilic adhesion aid is a molecule with amphiphilic structure, containing a polar group at one end and an organic segment containing a reactive functional group at the other end, the polar group produces intermolecular forces or chemical bonding with the surface groups of the metal powder, and the other end containing the reactive functional group of the organic segment produces strong intermolecular forces or physical entanglement or chemical reaction between the binder base and the metal powder, which acts as a bridge between the binder base and the metal powder, avoiding the separation of the binder base and the metal powder, and improving the coating effect of the binder on the metal powder.

[0004] However, the typical shortcomings of traditional BJ binders, such as poor print adaptability of different batches of binders due to fluctuations in raw materials, poor print consistency, high-temperature long-time drying or multi-stage debinding in post-molding treatment, affecting efficiency, and safety and environmental hazards caused by organic volatilization of some alcohol-containing binders in the printing process, cannot be solved. Therefore, it is urgent to develop a medium viscosity, controllable surface tension, and environmentally friendly water-based binder to optimize the BJ molding process and improve the strength of the metal green body and the density after sintering. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a water-based binder for stainless steel bonded jet additive manufacturing and a preparation method thereof. The viscosity is controlled at 8-12 mPa·s, and the surface tension is controlled at 33-37 mN / m to achieve ideal wetting and printing performance. The binder comprises a main solvent, a high molecular binder, a plasticizer and a wetting synergist, a surfactant, a rheological modifier and an antibacterial preservative; the main solvent is deionized water, which provides a water-based system environment; the high molecular binder is polyvinylpyrrolidone, which increases the bonding strength of the printed green body; the plasticizer and the wetting synergist are propylene glycol, which can reduce the brittleness of the binder and assist wetting; the surfactant is sodium dodecyl sulfate, which can reduce the surface tension and improve the spreading property; the rheological modifier is polyethylene glycol, which can adjust the viscosity and prevent nozzle blockage; and the antibacterial preservative can prevent mold and bacteria, prolong the storage period.

[0006] To achieve the above-mentioned purpose, according to the first aspect of the present application, a water-based binder for stainless steel bonded jet additive manufacturing is provided, and the mass percentage components thereof include: deionized water 80-88wt%, polyvinylpyrrolidone 8-10wt%, propylene glycol 2-5wt%, sodium dodecyl sulfate 0.2-1.0wt%, polyethylene glycol 1-3wt%, and antibacterial preservative 0.05-0.2wt%.

[0007] The antibacterial preservative is at least one of sodium benzoate, p-hydroxybenzoic acid ester, and nipagin ester.

[0008] In the second aspect, the present application provides a preparation method of the water-based binder for stainless steel bonded jet additive manufacturing, comprising the following steps:

[0009] S1: weigh the required raw materials according to the mass percentage;

[0010] S2: add deionized water to a constant temperature stirrer, set the temperature, the first rotation speed and the first stirring time;

[0011] S3: keep the temperature and the first rotation speed of S2, uniformly add polyvinylpyrrolidone, and fully stir and dissolve at a constant temperature and speed for a second stirring time;

[0012] S4: cooling down to 25℃ at a rate of 1℃ / min, while maintaining the first rotating speed synchronously;

[0013] S5: after the cooling down, adding polyethylene glycol, reducing the rotating speed to the second rotating speed, and continuing to stir for the first stirring time;

[0014] S6: adding propylene glycol, maintaining the second rotating speed, and continuing to stir for the first stirring time until the transmittance of the solution is greater than or equal to 95%, and then reducing the rotating speed to the third rotating speed again;

[0015] S7: adding the pre-prepared 5wt% SDS aqueous solution at a dropping rate of 1.0mL / min, maintaining the system temperature at 25℃, maintaining the third rotating speed synchronously, and detecting the pH value synchronously, and stopping the dropping when the pH value reaches a fixed value;

[0016] S8: adding the antibacterial preservative and the remaining deionized water, stirring at the third rotating speed, and continuing to stir for the third stirring time;

[0017] S9: turning off the constant temperature stirrer, standing for 2 hours to remove bubbles, until the height of the bubble layer is less than 1mm;

[0018] S10: after filtering through a nanofiltration membrane, sealing in a brown glass bottle, and storing at a limited temperature in the dark.

[0019] Further, in S2, the stirring temperature is 40-50℃.

[0020] Further, in S2, S5 and S6, the first stirring time is 5-10min.

[0021] Further, in S2-S4, the first rotating speed is 800-1000rpm;

[0022] In S5 and S6, the second rotating speed is 400-500rpm;

[0023] In S6-S8, the third rotating speed is 200-300rpm.

[0024] Further, in S3, the second stirring time is 30-50min;

[0025] In S8, the third stirring time is 10-20min.

[0026] Further, in S7, the final value of the pH value needs to reach 6.5-7.5.

[0027] Further, in S10, the storage temperature of the adhesive is 10-25℃.

[0028] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0029] 1. The water-based binder for stainless steel binder jet additive manufacturing according to the present application improves the printing adaptability and forming consistency. Based on the interfacial regulation effect of the surfactant (sodium dodecyl sulfate), the surface tension is controlled within the range of 36 mN / m ± 2, which can effectively wet the stainless steel powder and has good penetration effect, short infiltration time, and improves the forming consistency.

[0030] 2. The water-based binder for stainless steel binder jet additive manufacturing according to the present application has excellent atomization performance, which can optimize the adaptability with the nozzle. The rheological modifier (polyethylene glycol) and the high molecular binder (polyvinylpyrrolidone) synergistically act to achieve medium viscosity control (≤10 mPa·s) design, perfectly match the Piezo nozzle, and reduce the risk of nozzle blockage.

[0031] 3. The water-based binder for stainless steel binder jet additive manufacturing according to the present application can improve the green body structure strength and density. Polyvinylpyrrolidone anchors metal particles through pyrrolidone groups, and plasticizer (propylene glycol) inhibits dry stress cracking, synergistically improves the green body strength to ≥4.0 MPa and porosity ≤5%, provides uniform diffusion channels for debinding, and the sintered part has a density of >98.5%.

[0032] 4. The water-based binder for stainless steel binder jet additive manufacturing according to the present application has environmental friendliness and work safety guarantee. The main solvent is deionized water, which builds a zero VOC system, completely eliminates the environmental toxicity of alcohol solvents, and the concentration of benzene series in the working environment is <0.01 mg / m 3 , which meets the work safety guarantee.

[0033] 5. The water-based binder for stainless steel binder jet additive manufacturing according to the present application has high debinding efficiency and high sintering cleanliness. The organic component has a stepwise thermal decomposition characteristic, with a weight loss of ≥95% at 400°C and a carbon residue rate of <0.01 wt% at 800°C, and the sintered part has no carbon residue defects.

[0034] 6. The water-based binder for stainless steel binder jet additive manufacturing according to the present application has industrialized economy and storage stability. Industrial-grade raw materials are used for all components, which has low raw material cost; the antibacterial preservative inhibits the growth of microorganisms, guarantees the viscosity fluctuation ≤5% after 180 days of storage at 25°C in the dark, and the batch-to-batch viscosity RSD <2% (n=50). BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The preparation method flow chart of the water-based binder for stainless steel binder jet additive manufacturing according to the present application is shown in the figure.

[0036] Figure 2A schematic diagram of TGA test results of the embodiment of the present application is shown in the figure;

[0037] Figure 3 A schematic diagram of viscosity-temperature curves corresponding to different component contents of the embodiment of the present application is shown in the figure;

[0038] Figure 4 A schematic diagram of surface tension curves corresponding to different component contents of the embodiment of the present application is shown in the figure;

[0039] Figure 5 A SEM diagram of the adhesive effect of the binder and the powder of the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] In the embodiment of the present application, a water-based binder for stainless steel bonding spray additive manufacturing is provided, and the mass percentage of the components includes: deionized water 80-88wt%, polyvinylpyrrolidone 8-10wt%, propylene glycol 2-5wt%, sodium dodecyl sulfate 0.2-1.0wt%, polyethylene glycol 1-3wt%, and antibacterial preservative 0.05-0.2wt%.

[0042] Among them, the antibacterial preservative is at least one of sodium benzoate, p-hydroxybenzoic acid ester, and nipagin ester.

[0043] In another aspect of the present application, a preparation method of a water-based binder for stainless steel bonding spray additive manufacturing is provided, comprising the following steps:

[0044] S1: weighing the required raw materials according to the mass percentage;

[0045] S2: adding deionized water into a constant temperature stirrer, setting the temperature, the first rotation speed and the first stirring time;

[0046] S3: maintaining the temperature and the first rotation speed of S2, uniformly adding polyvinylpyrrolidone, and fully stirring and dissolving at a constant temperature and speed for a second stirring time;

[0047] S4: reducing the temperature to 25℃ at a rate of 1℃ / min, and synchronously maintaining the first rotation speed;

[0048] S5: after the temperature reduction is completed, adding polyethylene glycol, reducing the stirring speed to the second rotation speed, and continuing to stir for the first stirring time;

[0049] S6: add propylene glycol, maintain the second rotating speed, continue stirring for the first stirring time until the transmittance of the solution is ≥ 95%, and then reduce the stirring speed to the third rotating speed again;

[0050] S7: drop the pre-prepared 5wt% SDS aqueous solution at a dropping rate of 1.0 mL / min, maintain the third rotating speed of stirring at a constant temperature of 25℃, and simultaneously detect the pH value, and stop dropping when the pH value reaches a fixed value;

[0051] S8: add the antibacterial preservative and the balance of deionized water, stir at the third rotating speed, and continue stirring for the third stirring time;

[0052] S9: turn off the constant temperature stirrer, stand for 2 hours to remove bubbles, until the height of the foam layer is <1mm;

[0053] S10: after filtration by a nanofiltration membrane, seal in a brown glass bottle, and store at a limited temperature in the dark.

[0054] In S2, the stirring temperature is 40-50℃;

[0055] Further, in S2, S5 and S6, the first stirring time is 5-10min;

[0056] Further, in S2-S4, the first rotating speed is 800-1000rpm;

[0057] Further, in S3, the second stirring time is 30-50min;

[0058] Further, in S5 and S6, the second rotating speed is 400-500rpm;

[0059] Further, in S6-S8, the third rotating speed is 200-300rpm;

[0060] Further, in S7, the final value of the pH value needs to reach 6.5-7.5;

[0061] Further, in S8, the continued stirring time is 10-20min;

[0062] Further, in S10, the storage temperature of the adhesive is 10-25℃.

[0063] Example 1

[0064] The operation steps and condition parameters of this embodiment are the same as those of embodiment 1, but the mass percentages of the components are different. A water-based binder for stainless steel binder jet additive manufacturing includes the following components in mass percentages: deionized water 85.6wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 4.0wt%, sodium dodecyl sulfate 0.3wt%, polyethylene glycol 2wt%, and sodium benzoate 0.1wt%.

[0065] A preparation method of a water-based binder for stainless steel binder jet additive manufacturing includes the following steps:

[0066] S1: weigh the required raw materials according to the mass percentages;

[0067] S2: add deionized water to a constant temperature stirrer, set the temperature, first rotation speed, and first stirring time;

[0068] S3: maintain the temperature and first rotation speed of S2, uniformly add polyvinylpyrrolidone, and fully stir and dissolve at a constant temperature and speed for a second stirring time;

[0069] S4: reduce the temperature to 25℃ at a rate of 1℃ / min, and maintain the first rotation speed simultaneously;

[0070] S5: after the temperature reduction is complete, add polyethylene glycol, reduce the stirring speed to a second rotation speed, and continue stirring for a first stirring time;

[0071] S6: add propylene glycol, maintain the second rotation speed, continue stirring for a first stirring time until the transmittance of the solution is ≥95%, and then reduce the stirring speed to a third rotation speed;

[0072] S7: at a drop rate of 1.0mL / min, add the pre-prepared 5wt% SDS aqueous solution, maintain the system temperature at 25℃, maintain the third speed stirring simultaneously, and detect the pH value simultaneously, and stop adding when the pH value reaches a fixed value;

[0073] S8: add the remaining deionized water and the antibacterial preservative, stir at the third speed, and continue stirring for a third stirring time;

[0074] S9: turn off the constant temperature stirrer, stand for 2 hours to remove bubbles, and the height of the foam layer should be <1mm;

[0075] S10: after filtration through a nanofiltration membrane, seal in a brown glass bottle, and store in a limited temperature condition in the dark.

[0076] In S2, the stirring temperature is 40℃;

[0077] Further, in S2, S5, and S6, the first stirring time is 5min;

[0078] Furthermore, in S2-S4, the first rotational speed is 800 rpm;

[0079] Furthermore, in S3, the first stirring time is 30 minutes;

[0080] Furthermore, in S5 and S6, the second rotational speed is 500 rpm;

[0081] Furthermore, in S6-S8, the third rotational speed is 300 rpm;

[0082] Furthermore, in S7, the final pH value reaches 6.8;

[0083] Furthermore, in S8, the continued stirring time is 20 minutes;

[0084] Furthermore, in S10, the storage temperature of the adhesive is 25°C.

[0085] After testing, such as Figure 2 As shown, the binder prepared in this embodiment has a pH value of 6.8 as detected by a glass electrode at 25°C, a viscosity of 9.8 mPa·s as measured by a rotational viscometer, and a surface tension of 35.4 mN / m as measured by the platinum sheet method. It has moderate viscosity and good wettability at room temperature, and no stratification or flocculation was observed after 6 months of storage in the dark at 25°C. TGA test results show that the weight loss is ≥95% at 400°C and the carbon residue is <0.01 wt% at 800°C.

[0086] Example 2

[0087] A water-based adhesive for stainless steel bonding spray additive manufacturing comprises, by weight percentage: 84.9 wt% deionized water, 10.0 wt% polyvinylpyrrolidone, 3.0 wt% propylene glycol, 0.5 wt% sodium dodecyl sulfate, 1.5 wt% polyethylene glycol, and 0.1 wt% sodium benzoate.

[0088] After testing, such as Figure 2 As shown, the binder prepared in this embodiment has a pH value of 6.8 as detected by a glass electrode at 25°C, a viscosity of 10.5 mPa·s as measured by a rotational viscometer, and a surface tension of 37.0 mN / m as measured by the platinum sheet method. It has moderate viscosity and good wettability at room temperature, and no stratification or flocculation was observed after 6 months of storage in the dark at 25°C. TGA test results show that the weight loss is ≥95% at 400°C and the carbon residue is <0.01 wt% at 800°C.

[0089] Example 3

[0090] The operation steps and condition parameters of this embodiment are the same as those of example 1, but the mass percentages of components are different. A water-based binder for stainless steel binder jet additive manufacturing includes the following components with the mass percentages: deionized water 82.8wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 5.0wt%, sodium dodecyl sulfate 1.0wt%, polyethylene glycol 3.0wt%, and sodium benzoate 0.2wt%.

[0091] Experimental tests show that the binder prepared in this embodiment has a pH value of 6.8 at 25℃ detected by a glass electrode, a viscosity of 9.2mPa·s detected by a rotary viscometer, and a surface tension of 33.5mN / m detected by a platinum sheet method. The viscosity at room temperature is moderate and the wettability is relatively good. The binder does not delaminate or flocculate after being stored in the dark at 25℃ for 6 months. TGA test results show that the weight loss is ≥95% at 400℃ and the carbon residue rate is <0.01wt% at 800℃.

[0092] Example 4

[0093] The operation steps and condition parameters of this embodiment are the same as those of example 1, but the mass percentages of components are different. A water-based binder for stainless steel binder jet additive manufacturing includes the following components with the mass percentages: deionized water 87.75wt%, polyvinylpyrrolidone 9.0wt%, propylene glycol 2.0wt%, sodium dodecyl sulfate 0.2wt%, polyethylene glycol 1.0wt%, and sodium benzoate 0.05wt%. Since the total volume is <100%, deionized water is added to make up the mass percentage of 12.75wt% to make the total mass percentage of components 100%.

[0094] Experimental tests show that the binder prepared in this embodiment has a pH value of 6.8 at 25℃ detected by a glass electrode, a viscosity of 10.2mPa·s detected by a rotary viscometer, and a surface tension of 35.0mN / m detected by a platinum sheet method. The viscosity at room temperature is moderate and the wettability is relatively good. The binder does not delaminate or flocculate after being stored in the dark at 25℃ for 6 months. TGA test results show that the weight loss is ≥95% at 400℃ and the carbon residue rate is <0.01wt% at 800℃.

[0095] Example 5

[0096] The operation steps and condition parameters of this embodiment are the same as those of example 1, but the mass percentages of components are different. A water-based binder for stainless steel binder jet additive manufacturing includes the following components with the mass percentages: deionized water 82.8wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 5.0wt%, sodium dodecyl sulfate 1.0wt%, polyethylene glycol 3.0wt%, and sodium benzoate 0.2wt%.

[0097] In S2, the stirring temperature is 40℃.

[0098] Further, in S2, S5 and S6, the first stirring time is 5min.

[0099] Further, in S2-S4, the first rotating speed is 800 rpm.

[0100] Further, in S3, the second stirring time is 30 min.

[0101] Further, in S5 and S6, the second rotating speed is 400 rpm.

[0102] Further, in S6-S8, the third rotating speed is 200 rpm.

[0103] Further, in S7, the final value of the pH value is 6.5.

[0104] Further, in S8, the continuous stirring time is 10 min.

[0105] Further, in S10, the storage temperature of the binder is 10℃

[0106] Through experimental detection, the binder prepared in this embodiment has a pH value of 6.5 at 10℃, a viscosity of 10.3 mPa·s measured by a rotary viscometer, and a surface tension of 36.2 mN / m measured by a platinum sheet method. The viscosity at room temperature is moderate and the wettability is relatively good, but the parameters at room temperature are relatively high. The binder is stored in the dark for 6 months at 10℃ without delamination or flocculation. The TGA test result shows that the weight loss is ≥95% at 400℃ and the residual carbon rate is <0.01 wt% at 800℃.

[0107] Example 6

[0108] This embodiment has the same operation process and mass percentage of components as Example 1, but the specific parameters of the operation steps are different. A preparation method of a water-based binder for stainless steel bonding spray additive manufacturing, and the key condition parameters of the operation steps are as follows:

[0109] In S2, the stirring temperature is 50℃.

[0110] Further, in S2, S5 and S6, the first stirring time is 10 min.

[0111] Further, in S2-S4, the first rotating speed is 1000 rpm.

[0112] Further, in S3, the second stirring time is 50 min.

[0113] Further, in S5 and S6, the second rotating speed is 500 rpm.

[0114] Further, in S6-S8, the third rotating speed is 300 rpm.

[0115] Further, in S7, the final value of the pH value reaches 7.5.

[0116] Further, in S8, the continuous stirring time is 20 min.

[0117] Further, in S10, the storage temperature of the adhesive is 25℃

[0118] Through experimental detection, the adhesive prepared in the embodiment has a pH value of 7.5 at 25℃ detected by a glass electrode, a viscosity of 9.5 mPa·s detected by a rotary viscometer, and a surface tension of 34.2 mN / m detected by a platinum sheet method. The viscosity at room temperature is moderate and the wettability is relatively optimal. The adhesive is not layered or flocculated after being stored in the dark for 6 months at 25℃. The TGA test result shows that the weight loss is ≥95% at 400℃ and the residual carbon rate is <0.01 wt% at 800℃.

[0119] Example 7

[0120] The operation process and the mass percentage of components of the embodiment are the same as those of Example 1, but the specific parameters of the operation steps are different. A preparation method of a water-based adhesive for stainless steel bonding spray additive manufacturing, and the key condition parameters of the operation steps are as follows:

[0121] In S2, the stirring temperature is 45℃.

[0122] Further, in S2, S5 and S6, the first stirring time is 7.5 min.

[0123] Further, in S2-S4, the first rotating speed is 900 rpm.

[0124] Further, in S3, the second stirring time is 40 min.

[0125] Further, in S5 and S6, the second rotating speed is 450 rpm.

[0126] Further, in S6-S8, the third rotating speed is 250 rpm.

[0127] Further, in S7, the final value of the pH value reaches 7.0.

[0128] Further, in S8, the continuous stirring time is 15 min.

[0129] Further, in S10, the storage temperature of the adhesive is 17.5℃

[0130] The prepared adhesive of the embodiment is detected by experiment, and the pH value is 7.0 detected by a glass electrode under the condition of 17.5℃, the viscosity is 9.8 mPa·s detected by a rotary viscometer, the surface tension is 35.4 mN / m detected by a platinum plate method, the viscosity at room temperature is moderate and the wettability is relatively optimal, and there is no delamination or flocculation after storage for 6 months in the dark at 25℃, the TGA test result shows that the weight loss is ≥95% at 400℃ and the residual carbon rate is <0.01 wt% at 800℃.

[0131] Example 8

[0132] The operation process and the mass percentage of components of the embodiment are the same as those of Example 8, but the specific parameters of the operation steps are different. A preparation method of a water-based adhesive for stainless steel bonding spray additive manufacturing, and the key condition parameters of the operation steps are as follows:

[0133] In S2, the stirring temperature is 50℃.

[0134] Further, in S2, S5 and S6, the first stirring time is 5 min.

[0135] Further, in S2-S4, the first rotating speed is 1000 rpm.

[0136] Further, in S3, the second stirring time is 30 min.

[0137] Further, in S5 and S6, the second rotating speed is 400 rpm.

[0138] Further, in S6-S8, the third rotating speed is 300 rpm.

[0139] Further, in S7, the final value of the pH value reaches 6.5.

[0140] Further, in S8, the continuous stirring time is 20 min.

[0141] Further, in S10, the storage temperature of the adhesive is 10℃.

[0142] The prepared adhesive of the embodiment is detected by experiment, and the pH value is 6.5 detected by a glass electrode under the condition of 10℃, the viscosity is 10.0 mPa·s detected by a rotary viscometer, the surface tension is 35.9 mN / m detected by a platinum plate method, the viscosity at room temperature is moderate and the wettability is relatively optimal, and there is no delamination or flocculation after storage for 6 months in the dark at 25℃, the TGA test result shows that the weight loss is ≥95% at 400℃ and the residual carbon rate is <0.01 wt% at 800℃.

[0143] Comparative Example 1

[0144] The operation steps and condition parameters of the comparative example 1 are the same as those of the example 1, but the polyvinylpyrrolidone is missing in the components, and the mass percentage of the components includes: deionized water 93.6wt%, propylene glycol 4.0wt%, sodium dodecyl sulfate 0.3wt%, polyethylene glycol 2wt%, sodium benzoate 0.1wt%.

[0145] Through experimental detection, the viscosity is only 2.3mPa·s measured by a rotary viscometer, and the surface tension is 21.8mN / m measured by a platinum plate method, and the powder cannot be bonded.

[0146] Comparative example 2

[0147] The operation steps and condition parameters of the comparative example 2 are the same as those of the example 1, but sodium dodecyl sulfate is replaced by sodium dodecyl sulfonate in the components, and the mass percentage of the components includes: deionized water 85.6wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 4.0wt%, sodium dodecyl sulfonate 0.3wt%, polyethylene glycol 2wt%, sodium benzoate 0.1wt%.

[0148] Through experimental detection, the viscosity is 10.5mPa·s measured by a rotary viscometer, and the surface tension is as high as 40.1mN / m measured by a platinum plate method, and the surface tension is too high, the powder bed infiltration effect is poor, and the infiltration time is long.

[0149] Comparative example 3

[0150] The operation steps and condition parameters of the comparative example 3 are the same as those of the example 1, but propylene glycol is missing in the components, and the mass percentage of the components includes: deionized water 89.6wt%, polyvinylpyrrolidone 8.0wt%, sodium dodecyl sulfate 0.3wt%, polyethylene glycol 2wt%, sodium benzoate 0.1wt%.

[0151] Through experimental detection, the viscosity is 8.7mPa·s measured by a rotary viscometer, and the surface tension is as high as 36.7mN / m measured by a platinum plate method, and the viscosity is slightly reduced but the surface tension is increased, and the performance is slightly poor.

[0152] Comparative example 4

[0153] The operation steps and condition parameters of the comparative example 4 are the same as those of the example 1, but polyethylene glycol is missing in the components, and the mass percentage of the components includes: deionized water 87.6wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 4.0wt%, sodium dodecyl sulfate 0.3wt%, sodium benzoate 0.1wt%.

[0154] Through experimental detection, the viscosity is 9.3mPa·s measured by a rotary viscometer, and the surface tension is as high as 38.2mN / m measured by a platinum plate method, and the viscosity is slightly reduced but the surface tension is increased, and the performance is slightly poor.

[0155] Comparative Example 5

[0156] The operation steps and condition parameters of the present comparative example are the same as those of Example 1, but the antibacterial preservative is missing in the components, and the mass percentage of the components includes: deionized water 85.7wt%, polyvinylpyrrolidone 8.0wt%, propylene glycol 4.0wt%, sodium dodecyl sulfonate 0.3wt%, polyethylene glycol 2wt%.

[0157] Through experimental detection, the viscosity is 9.8 mPa·s measured by a rotary viscometer, and the surface tension is 35.4 mN / m measured by the platinum plate method, but there is slight flocculation during long-term storage.

[0158] Comparative Example 6

[0159] The operation process of the present example and the operation parameters of S1-S9 and the mass percentage of the components are the same as those of Example 1, but in S10, an unsuitable storage temperature is selected, and the difference lies in that in S10, the storage temperature of the adhesive is 5℃

[0160] Through experimental detection, flocculation phenomenon occurs during low-temperature storage.

[0161] Comparative Example 7

[0162] The operation process of the present example and the operation parameters of S1-S9 and the mass percentage of the components are the same as those of Example 1, but in S10, an unsuitable storage temperature is selected, and the difference lies in that in S10, the storage temperature of the adhesive is 32℃

[0163] Through experimental detection, the actual use effect is slightly worse, and the viscosity and green strength are both decreased.

[0164] The viscosity, surface tension, and TGA test of the adhesive of Examples 1-8 and Comparative Examples 1-7 are tested, and the test results are shown in Table 1 or Table 2.

[0165] Table 1 Test results of Examples 1-8

[0166]

[0167] Table 2 Test results of Comparative Examples 1-7

[0168]

[0169] The test results of Table 1 and Table 2 show that by adjusting the component ratio of the adhesive, optimizing the preparation process and storage conditions, the viscosity, surface tension and stability of the adhesive can be precisely optimized. The specific regulation is as follows:

[0170] (1) The key regulation of the core component is as follows:

[0171] By adjusting the content of polyvinylpyrrolidone, the viscosity of the adhesive can be effectively controlled. When PVP is absent (Comparative Example 1), the viscosity drops to 2.3 mPa-s, and the adhesive ability is completely lost. As shown in Figure 3 and Figure 5 Even if the temperature changes, the product viscosity increases in turn with the increase of the mass ratio of PVP. PVP acts as a thickening agent to increase the viscosity of the system through molecular chain entanglement, and its content has a certain positive correlation with the viscosity.

[0172] As shown in Figure 4 By adjusting the content of sodium dodecyl sulfate and the compounding ratio of propylene glycol / polyethylene glycol, the surface tension can be stabilized at 33.5-37.0 mN / m. When sodium dodecyl sulfonate is used instead of SDS, the surface tension rises to 40.1 mN / m, and the wettability decreases significantly; when propylene glycol or polyethylene glycol is absent, the surface tension rises to 36.7-38.2 mN / m, it is concluded that SDS improves wettability by reducing the surface energy of the solution, and propylene glycol / polyethylene glycol synergistically enhances the penetration effect.

[0173] As shown in

[0174] (2) The optimization boundary of process parameters is as follows:

[0175] As shown in

[0176] As shown in Example 1 and Examples 5, 6, and 8, the final pH value (6.5-7.5) has limited effect on performance, but the comprehensive performance is optimal when the pH is 6.8 (Example 1) or 7.0 (Example 7).

[0177] As shown in Example 1 and Comparative Examples 6-7 and Examples 5 and 8, the storage temperature (10-25°C) is a critical parameter for stability: ≤10°C causes flocculation; ≥32°C causes viscosity and green strength to decrease.

[0178] (3) Verification of non-substitutability of components

[0179] When sodium dodecyl sulfonate was used to replace SDS, although the viscosity was qualified (10.5 mPa·s), the surface tension was as high as 40.1 mN / m. Since the sulfonate group has poor affinity with metal powder, it cannot effectively reduce the solid-liquid interface energy, resulting in the failure of infiltration.

[0180] When propylene glycol or polyethylene glycol was deleted, the surface tension increased significantly (36.7-38.2 mN / m). The polyhydric alcohol regulates the arrangement of water molecules through hydrogen bonds, and the deletion weakens the synergistic surface tension reduction effect of SDS.

[0181] (4) Stability of the product

[0182] Those skilled in the art will readily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water-based adhesive for stainless steel adhesive spray additive manufacturing, characterized in that, The components by weight percentage include: 80-88 wt% deionized water, 8-10 wt% polyvinylpyrrolidone, 2-5 wt% propylene glycol, 0.2-1.0 wt% sodium dodecyl sulfate, 1-3 wt% polyethylene glycol, and 0.05-0.2 wt% antibacterial preservative.

2. The water-based adhesive for stainless steel bonding spray additive manufacturing according to claim 1, characterized in that, The antibacterial preservative is at least one of sodium benzoate, parabens, and parabens.

3. The water-based adhesive for stainless steel bonding spray additive manufacturing according to claim 2, characterized in that, The total mass percentage of the components is 100%. If the total mass percentage of the components is less than 100%, deionized water is used to make up to 100%.

4. A method for preparing a water-based binder for stainless steel bonded spray additive manufacturing as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: Weigh the required raw materials according to the mass percentage; S2: Add deionized water to the thermostatic stirrer, and set the temperature, first speed and first stirring time; S3: Maintain the temperature and first rotation speed of S2, add polyvinylpyrrolidone at a uniform speed, and stir thoroughly to dissolve at a constant temperature and speed for the second stirring time. S4: Cool down to 25℃ at a rate of 1℃ / min while maintaining the first rotation speed; S5: After cooling is complete, add polyethylene glycol, reduce the stirring speed to the second rotation speed, and continue stirring for the first stirring time; S6: Add propylene glycol, maintain the second speed, and continue stirring for the first stirring time until the solution transmittance is ≥95%, then reduce the stirring speed again to the third speed; S7: Add the pre-prepared 5wt% SDS aqueous solution dropwise at a dropping rate of 1.0 mL / min, keep the system temperature constant at 25℃, maintain the third stirring speed simultaneously, and monitor the pH value at the same time. Stop the dropping once the pH value reaches a fixed value. S8: Add antibacterial preservative and the remaining deionized water, stir at the third speed, and continue stirring for the third stirring time; S9: Turn off the thermostatic stirrer and let it stand for 2 hours to remove bubbles until the foam layer height is <1mm; S10: After being filtered through a nanofiltration membrane, it is sealed in a brown glass bottle and stored in the dark under limited temperature conditions.

5. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 4, characterized in that, In S2, the stirring temperature is 40-50°C.

6. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 5, characterized in that, In S2, S5 and S6, the first stirring time is 5 to 10 minutes.

7. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 6, characterized in that, In S2-S4, the first rotational speed is 800-1000 rpm; In S5 and S6, the second rotational speed is 400-500 rpm; In S6-S8, the third rotational speed is 200-300 rpm.

8. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 7, characterized in that, In S3, the second stirring time is 30-50 minutes; In S8, the third stirring time is 10 to 20 minutes.

9. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 4, characterized in that, In S7, the final pH value needs to reach 6.5 to 7.

5.

10. The method for preparing the water-based binder for stainless steel adhesive spray additive manufacturing according to claim 4, characterized in that, In S10, the storage temperature of the adhesive is 10-25°C.

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