Press roller surface titanizing process for biodegradable film processing

Abstract

The invention discloses a compression roller surface titanizing process for biodegradable film processing. The compression roller surface titanizing process comprises the steps of ultra-clean pretreatment, gradient titanium layer electroplating, microstructure strengthening, intelligent closed-loop purification treatment, intelligent drying, defect detection and self-adaptive process calibration. According to the method, an atomic-scale clean surface is created for electroplating through ultra-clean pretreatment, the thickness of a plating layer with the thickness of 20 microns is achieved by combining a gradient titanium layer electroplating technology, the porosity of the plating layer is smaller than or equal to 0.8 / s through microstructure strengthening, intelligent closed-loop purification and self-adaptive calibration are matched, and finally the core advantages that the service life of the compression roller is prolonged, and titanium residues of a biodegradable film are reduced are achieved. The process meets the core requirements of'zero pollution, super wear resistance and long service life 'of biodegradable film production on the compression roller, solves the problems of non-uniform film thickness, poor light transmission and poor interface bonding caused by the traditional process, and has great industrial value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface treatment, and particularly relates to a titanium plating process for a compression roller for processing biodegradable films. BACKGROUND

[0002] Titanium plating is a chemical method of attaching titanium metal to the surface of another object. The titanium plating layer has excellent corrosion resistance and can be used to protect the plated object and improve surface wear resistance. Titanium plating on the surface of a compression roller is a process of plating titanium metal or compounds (such as titanium nitride) on the surface of the compression roller, mainly used to improve surface wear resistance, corrosion resistance and service life.

[0003] In the production process of biodegradable films, traditional chromium-plated compression rollers have a risk of chromium ion migration, and existing titanium plating processes still have some defects and shortcomings. For example, the uniformity of the plating layer is poor, the edges of the compression roller are thin due to fast heat dissipation, which easily causes uneven film thickness, and the porosity of the electroplated layer is large, which easily causes metal impurities on the film surface and a series of other shortcomings.

[0004] Therefore, it is necessary to continuously improve the titanium plating process to meet the core needs of "zero pollution, super wear resistance and long service life" of the compression roller for biodegradable film production, so as to improve the industrial value. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the shortcomings of the prior art, the present application optimizes the cleaning, electroplating, baking and passivation processes to form a 20μm titanium plating layer with high hardness, low friction coefficient and high density on the surface of the compression roller, thereby solving the problems of uneven film thickness, poor light transmission and poor interface bonding caused by traditional processes.

[0007] (II) Technical solutions

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a titanium plating process for a compression roller for processing biodegradable films, comprising the following steps:

[0009] Step 1: super-clean pretreatment: sequentially performing surface cleaning, thermal stress relief, composite cleaning, water circulation purification and hot air drying treatment on the compression roller substrate;

[0010] Step 2: gradient titanium plating layer: depositing a 20μm titanium plating layer in an electroplating solution containing yttrium additive by a double-pulse power supply, and simultaneously applying an axial temperature gradient, with a center zone of 55±1℃ and an edge zone of 58±1℃;

[0011] Step 3: microstructure strengthening: implementing three-stage gradient baking in an argon / nitrogen mixed atmosphere with a volume ratio of 3:1, with gradient temperatures of 150℃ / 1h, 300℃ / 2h and 450℃ / 1h.

[0012] Step four, intelligent closed-loop purification treatment: including three water washing processes of multi-stage countercurrent pure water washing, self-adaptive acid-base cooperative cleaning and dynamic temperature control water washing;

[0013] Step five, intelligent drying and defect detection: vacuum drying is simultaneously performed with laser confocal scanning, and the sampling point density is ≥ 50 points / cm²;

[0014] Step six, self-adaptive process calibration: based on multi-source sensing data, the plating current density, baking temperature curve and passivation time are optimized in real time.

[0015] As a preferred solution, the ultra-clean pretreatment in step one specifically includes:

[0016] a) Surface cleaning: 40 kHz alkaline solution (NaOH 50 g / L + Na3PO4 30 g / L, pH = 12.5) cleaning for 20 min;

[0017] b) Warm stress relief: under argon protection, the temperature is raised to 600°C at 4°C / min, and after holding for 2.5 h, it is slowly cooled (≤ 3°C / min);

[0018] c) Composite cleaning: 10% oxalic acid (60°C) and 5% NaOH (60°C) are alternately sprayed, and each action lasts for 4 min;

[0019] d) Water circulation purification: three-stage countercurrent rinsing (conductivity ≤ 5 μS / cm);

[0020] e) Hot air drying: 100°C high-speed hot air (15 m / s) penetrates the roller surface groove.

[0021] As a preferred solution, the gradient titanium plating layer in step two contains:

[0022] Plating solution formula: Ti 140 g / L + Y 2.5 g / L + sodium glycolate 25 g / L + sodium polydithiobispropane sulfonate 0.8 g / L;

[0023] Pulse parameters: forward current density 3.2 A / dm², reverse current density 0.6 A / dm²;

[0024] Axial temperature control: center zone 54°C, transition zone 56°C and edge zone 58°C.

[0025] As a preferred solution, the yttrium element in the plating solution formula is ( )3 form addition, concentration gradient: 2.2 g / L in the center to 2.8 g / L at the edge, the average grain size of the coating is ≤35 nm by occupying titanium grain boundary vacancies with yttrium ions, and the Vickers hardness is ≥800 HV.

[0026] As a preferred solution, in the step three microstructure strengthening: the cooling rate of each stage of gradient baking: ≤5 ℃ / min in the 150-300 ℃ stage and ≤3 ℃ / min in the 300-450 ℃ stage; the argon / nitrogen mixed gas flow rate is 8 L / min, and the oxygen content is ≤50 ppm; and the grain refinement mechanism is: occupying titanium grain boundary vacancies with ions, so that the average grain size is ≤35 nm.

[0027] As a preferred solution, the step four intelligent closed-loop purification treatment comprises:

[0028] A1, multi-stage countercurrent pure water washing: a three-stage water washing system adopts cross-flow filtration technology, 5 μm, 1 μm and 0.1 μm filter cartridges are arranged in each stage, and ultrasonic cavitation is introduced in the second-stage water washing;

[0029] A2, self-adaptive acid-base collaborative cleaning: through linkage control of ORP sensors and temperature, when it is detected that the concentration is >0.1 ppm, the citric acid concentration is automatically increased by 10%;

[0030] A3, dynamic temperature control water washing: a plate heat exchanger recovers acid-base cleaning waste heat.

[0031] As a preferred solution, the step five intelligent drying and defect detection is specifically: under a vacuum degree of Pa 110 ℃ drying for 40 minutes, and simultaneously using a longitudinal resolution ≤5 nm laser confocal scanner to detect porosity, and cooperating with an eddy current thickness gauge to generate a thickness distribution cloud map, when it is detected that the local thickness deviation is >0.5 μm, the step six current density compensation program is triggered.

[0032] As a preferred solution, the step six self-adaptive process calibration establishes a process parameter-coating quality mapping model through an LSTM neural network, the input variables include current density deviation ΔJ, temperature gradient δT and porosity P, and the output adjustment amount satisfies:

[0033] current density correction value J_corrected=J0×(1+0.15×tanh(ΔJ))

[0034] baking temperature correction value T_new=T_set+0.8×δT, and the control period is ≤30 seconds.

[0035] As a preferred solution, a passivation sub-step is further included: after the intelligent closed-loop purification treatment of step four, a citric acid-molybdate composite passivation solution is applied, with a composition of citric acid 85 g / L + sodium molybdate 8 g / L + sodium gluconate 12 g / L, the pH value is dynamically maintained at 4.8-5.2, the passivation time is 15±2 minutes, and a dense oxide film is formed.

[0036] As a preferred solution, the titanium plating layer on the surface of the titanium-plated compression roller has a thickness of 20±0.5 μm, a porosity of ≤0.8 pieces / cm², a friction coefficient of ≤0.15, and an axial hardness gradient of 820±10 HV in the center region to 780±10 HV in the edge region, and is suitable for a PLA / PBAT biodegradable film compression production line.

[0037] (Three) beneficial effects

[0038] Compared with the prior art, the present application provides a titanium plating process for the surface of a compression roller used for biodegradable film processing, which has the following beneficial effects:

[0039] Firstly, the present application creates an atomic-level clean surface for electroplating through super-clean pretreatment, and realizes a 20 μm plating layer thickness in combination with a gradient titanium plating layer technology, and makes the plating layer porosity ≤0.8 pieces / cm² through microstructure strengthening. , and finally achieves the core advantages of improving the service life of the compression roller and reducing the titanium residue of the biodegradable film. The process meets the core needs of "zero pollution, ultra-wear resistance, and long service life" of the compression roller for biodegradable film production, has great industrial value, and is especially suitable for the manufacture of compression rollers with zero metal pollution and high wear resistance. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a schematic diagram of the overall process of the present application;

[0041] Figure 2 is a closed-loop control flowchart of the present application. DETAILED DESCRIPTION

[0042] In order to better understand the purpose, structure and function of the present application, the following will combine the drawings and specific embodiments to further explain the titanium plating process for the surface of a compression roller used for biodegradable film processing.

[0043] Example 1

[0044] Reference Figures 1-2 The titanium plating process for the surface of a compression roller used for biodegradable film processing includes the following steps:

[0045] Step one, super-clean pretreatment: sequentially performing surface cleaning, thermal stress relief, composite cleaning, water circulation purification and hot air drying treatment on the compression roller substrate;

[0046] Step two, gradient titanium plating: deposit 20 μm titanium plating layer in plating solution containing yttrium additive through double pulse power supply, and synchronously apply axial temperature gradient, with the center zone being 55±1℃ and the edge zone being 58±1℃;

[0047] Step three, microstructure strengthening: implement three-stage gradient baking in argon / nitrogen mixed atmosphere with a volume ratio of 3:1, with gradient temperatures of 150℃ / 1h, 300℃ / 2h and 450℃ / 1h;

[0048] Step four, intelligent closed-loop purification treatment: including three water washing processes of multi-stage countercurrent pure water washing, self-adaptive acid-base synergistic cleaning and dynamic temperature control water washing;

[0049] Step five, intelligent drying and defect detection: vacuum drying is synchronously performed with laser confocal scanning, and the sampling point density is ≥50 points / cm²;

[0050] Step six, self-adaptive process calibration: based on multi-source sensing data, real-time optimization of plating current density, baking temperature curve and passivation time is performed.

[0051] Specifically, the present application includes six process steps of super-clean pretreatment, gradient titanium plating, microstructure strengthening, intelligent closed-loop purification treatment, intelligent drying and defect detection, and self-adaptive process calibration, in which:

[0052] The super-clean pretreatment specifically includes:

[0053] a) surface cleaning: 40 kHz alkaline solution (NaOH 50g / L+Na3PO4 30g / L, pH=12.5) cleaning for 20 min;

[0054] b) heating stress relief: under argon protection, heating to 600℃ at a rate of 4℃ / min, holding for 2.5h and then slow cooling (≤3℃ / min);

[0055] c) composite cleaning: alternately spraying 10% oxalic acid (60℃) and 5% NaOH (60℃) for 4 min each time;

[0056] d) water circulation purification: three-stage countercurrent rinsing (conductivity ≤5 μS / cm);

[0057] e) hot air drying: 100℃ high-speed hot air (15m / s) penetrating the roller surface groove.

[0058] In general, it adopts alkaline ultrasonic cleaning to strip the oil stains of μm level by cavitation effect at 40 kHz, and then argon gas protection stress relief to make dislocation recombination at 600℃ to further reduce residual stress; followed by oxalic acid / NaOH alternate cleaning to dissolve metal oxides and play a neutralizing role, and then three-stage countercurrent rinsing to make its conductivity ≤5 μS / cm to block ion residues, and finally high-speed hot air drying to create an atomic level clean surface for electroplating.

[0059] Further, the step two gradient electroplating titanium layer of the present application comprises:

[0060] Electroplating solution formula: Ti 140g / L+Y 2.5g / L+ sodium glycolate 25g / L+ sodium polydithiobispropane sulfonate 0.8g / L;

[0061] Pulse parameters: forward current density 3.2 A / dm², reverse current density 0.6 A / dm²;

[0062] Axial temperature control: center zone 54℃, transition zone 56℃ and edge zone 58℃.

[0063] In the electroplating solution formula, yttrium element is added in the form of ( )3, with a concentration gradient from 2.2g / L in the center zone to 2.8g / L in the edge zone, so that the average grain size of the plated layer is ≤35nm and the Vickers hardness is ≥800HV by occupying titanium grain boundary vacancies with yttrium ions.

[0064] Among them, it should be noted that the gradient electroplating titanium layer is formed based on the principle of electrochemical deposition, which specifically manifests as: a double pulse power excites a reduction reaction in a yttrium-containing electroplating solution, and an axial temperature gradient (54℃ in the center to 58℃ in the edge) compensates for heat loss at the edge, so that the deposition rate is increased by 22%, and the pulse parameters are used to suppress dendrite growth to form a 20μm dense titanium layer.

[0065] After the electroplating titanium layer is formed, baking follows, and in the step three microstructure strengthening of the present application: the cooling rate of each stage of gradient baking is ≤5℃ / min at 150 to 300℃ and ≤3℃ / min at 300 to 450℃; the argon / nitrogen mixed gas flow rate is 8L / min, and the oxygen content is ≤50ppm; the grain refinement mechanism: Ions occupy Ti grain boundary vacancies, so that the average grain size is ≤35nm.

[0066] Specifically, gradient baking is implemented in an Ar / N2 mixed atmosphere in three stages of gradient baking, namely 150℃ (1h), 300℃ (2h) to 450℃ (1h), and then heat stress is released by controlling the cooling rate (≤3℃ / min), The ion embedding into the titanium lattice produces lattice distortion energy, and refines the grain size to below 35 nm.

[0067] Embodiment 2

[0068] The present application is a kind of titanium plating process for the surface of compression roller used in biodegradable film processing, which uses intelligent closed-loop purification treatment after gradient baking, and comprises:

[0069] A1, multi-stage countercurrent pure water washing: a three-stage water washing system uses cross-flow filtration technology, 5 μm, 1 μm to 0.1 μm filter cartridges are arranged in each stage, and ultrasonic cavitation is introduced in the second-stage water washing;

[0070] A2, self-adaptive acid-base synergistic cleaning: through ORP sensor and temperature linkage control, when the detection value is greater than 0.1 ppm, the citric acid concentration is automatically increased by 10%;

[0071] A3, dynamic temperature control water washing: plate heat exchanger recovers acid-base cleaning waste heat.

[0072] Through three-stage countercurrent pure water washing: 0.1 μm filter + 68 kHz ultrasonic cavitation to remove particles - ORP feedback acid-base cleaning - waste heat recovery temperature control water washing, further reducing particle residues.

[0073] In order to better complete the gradient electroplated titanium layer, after the intelligent closed-loop purification treatment of step four in the present application, a citric acid-molybdate composite passivation solution is applied, which is composed of citric acid 85 g / L + sodium molybdate 8 g / L + sodium gluconate 12 g / L, the pH value is dynamically maintained at 4.8-5.2, and the passivation time is 15±2 minutes, so as to form a dense oxide film. The titanium plating layer on the surface of the titanium plating roller has a thickness of 20±0.5 μm, a porosity of ≤0.8 pieces / cm², a friction coefficient of ≤0.15, and an axial hardness gradient of: center area 820±10 HV to edge area 780±10 HV, which is suitable for PLA / PBAT biodegradable film calendering production line.

[0074] Further, the present application also has an intelligent drying and defect detection link, specifically: drying at 110°C for 40 minutes under Pa vacuum, simultaneously detecting the porosity by using a laser confocal scanner with longitudinal resolution ≤5 nm, and generating a thickness distribution cloud map by using an eddy current thickness gauge, when detecting that the local thickness deviation is >0.5 μm, triggering the current density compensation program of step six, which can real-time locate the area with thickness deviation >0.5 μm.

[0075] In the present application, intelligent control is also a big advantage, the self-adaptive process calibration establishes a process parameter-plating layer quality mapping model through LSTM neural network, the input variables include current density deviation ΔJ, temperature gradient δT and porosity P, and the output adjustment amount satisfies: ​

[0076] Current density correction value J_corrected = J0 x (1 + 0.15 x tanh (Delta J))

[0077] Baking temperature correction value T_new = T_set + 0.8 x delta T, control period <= 30 seconds.

[0078] Taking a SUS420 stainless steel press roller for a PLA film production line as an example, the parameter execution includes electroplating liquid, gradient baking and passivation treatment. The experimental effect verification is shown in Table 1 as follows:

[0079] Test item Results Test standard Coating thickness 20.3 ± 0.2 μm GB / T 6462 Bonding strength 48.6 MPa ISO 4624 Surface roughness Ra 0.031 μm ISO 4287 Biodegradable film Ti residue 0.038 ppm ISO 17294-2

[0080] Table 1

[0081] The LSTM model can optimize the process in real time, and the standard deviation of the coating thickness is reduced from ±1.2 μm to ±0.3 μm, improving the coating consistency. The process of the application meets the core needs of the press roller for biodegradable film production, such as "zero pollution, super wear resistance and long service life", solves the problems of uneven film thickness, poor light transmission and poor interface bonding caused by traditional processes, and has great industrial value.

[0082] It can be understood that the present application is described through some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application belong to the scope of protection of the present application.

Claims

1. A process for plating titanium on the surface of a compression roller used for processing biodegradable films, characterized by, The method comprises the following steps: Step one, super-clean pretreatment: sequentially performing surface cleaning, warming stress relief, composite cleaning, water circulation purification and hot air drying treatment on the compression roller matrix; Step two, gradient titanium plating layer: depositing a 20 μm titanium plating layer in an electroplating solution containing yttrium additives through a double-pulse power supply, and synchronously applying an axial temperature gradient, with the center zone being 55±1℃ and the edge zone being 58±1℃; Step three, microstructure strengthening: implementing three-stage gradient baking in a mixed gas atmosphere of argon and nitrogen in a volume ratio of 3:1, with the gradient temperature being 150℃ / 1h, 300℃ / 2h and 450℃ / 1h; Step four, intelligent closed-loop purification treatment: comprising three water washing processes of multi-stage countercurrent pure water washing, self-adaptive acid-alkali collaborative cleaning and dynamic temperature control water washing; Step five, intelligent drying and defect detection: vacuum drying is synchronously performed with laser confocal scanning, with a sampling point density of ≥50 points / cm²; Step six, self-adaptive process calibration: based on multi-source sensing data, real-time optimization of electroplating current density, baking temperature curve and passivation time.

2. The process for titanium plating on the surface of a compression roller for processing biodegradable films according to claim 1, characterized in that, The super-clean pretreatment in step one specifically comprises: a) surface cleaning: 40 kHz alkaline solution cleaning for 20 min; b) warming stress relief: under argon protection, heating to 600℃ at a rate of 4℃ / min, holding for 2.5h and then slowly cooling; c) composite cleaning: alternately spraying 10% oxalic acid and 5% NaOH, with a single action time of 4 min; d) water circulation purification: three-stage countercurrent rinsing; e) hot air drying: 100℃ high-speed hot air penetration through the roller surface grooves.

3. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. The gradient titanium plating layer in step two comprises: Electrolyte formulation: Ti 140 g / L + Y 2.5 g / L + Sodium Glycolate 25 g / L + Sodium Polydithiobispropane Sulfonate 0.8 g / L; pulse parameters: forward current density 3.2 A / dm², reverse current density 0.6 A / dm²; axial temperature control: center zone 54℃, transition zone 56℃ and edge zone 58℃.

4. The process as claimed in claim 3, wherein the titanium plating on the surface of the compression roller for processing biodegradable films is characterized by, The yttrium element in the electroplating solution formulation is... ( Yttrium ions are added in the form of 3, with a concentration gradient from 2.2 g / L in the central region to 2.8 g / L in the edge region. By occupying the vacancies at the titanium grain boundaries, the average grain size of the coating is ≤35 nm, and the Vickers hardness is ≥800 HV.

5. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. The step three microstructure strengthening: gradient baking each stage cooling rate: 150 to 300 ℃ stage ≤5 ℃ / min, 300 to 450 ℃ stage ≤3 ℃ / min; argon / nitrogen mixed gas flow rate 8 L / min, oxygen content ≤50 ppm; grain refinement mechanism: The ions occupy the Ti grain boundary vacancies, so that the average grain size is ≤35 nm.

6. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. The intelligent closed-loop purification treatment in step four comprises: A1, multi-stage countercurrent pure water washing: a three-stage water washing system adopts cross-flow filtration technology, with 5 μm, 1 μm to 0.1 μm filter cartridges set at each stage, and ultrasonic cavitation is introduced in the second-stage water washing; A2, adaptive acid-base synergistic cleaning: through the ORP sensor and temperature linkage control, when detecting When the concentration > 0.1 ppm, automatically increase the citric acid concentration by 10%; A3, dynamic temperature control water washing: plate heat exchanger recovers acid-alkali cleaning waste heat.

7. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. Step five, intelligent drying and defect detection, specifically involves: in... Drying at 110℃ for 40 minutes under a vacuum of Pa, while simultaneously using a laser confocal scanner with a longitudinal resolution of ≤5nm to detect porosity, and generating a thickness distribution cloud map with an eddy current thickness gauge. When a local thickness deviation >0.5μm is detected, the current density compensation procedure in step six is ​​triggered.

8. The titanium plating process for the surface of a pressure roller used in biodegradable membrane processing according to claim 7, characterized in that... The self-adaptive process calibration in step six establishes a process parameter-plating layer quality mapping model through an LSTM neural network, the input variables include current density deviation ΔJ, temperature gradient δT and porosity P, and the output adjustment amount satisfies: current density correction value J_corrected=J0×(1+0.15×tanh(ΔJ)) baking temperature correction value T_new=T_set+0.8×δT, with a control period of ≤30 seconds.

9. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. It also comprises a passivation treatment sub-step: after the intelligent closed-loop purification treatment in step four, a citric acid-molybdate composite passivation solution is applied, with a composition of citric acid 85 g / L + sodium molybdate 8 g / L + sodium gluconate 12 g / L, with the pH value dynamically maintained at 4.8-5.2, the passivation time being 15±2 minutes, and a dense oxide film is formed.

10. The process as claimed in claim 1, wherein the surface of the compression roller is coated with titanium for processing biodegradable films. The titanium-plated compression roller has a titanium-plated layer with a thickness of 20±0.5μm, a porosity of ≤0.8 / cm², a friction coefficient of ≤0.15, and an axial hardness gradient of 820±10HV in the center area to 780±10HV in the edge area, and is suitable for a PLA / PBAT biodegradable film compression production line.

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