A method of curing glass syringe graduation lines

Abstract

The application discloses a kind of solidification methods of glass syringe scale line.The method first mixes lead-free low-melting glass powder, inorganic pigment and organic carrier to make glaze;Then the glass syringe barrel is cleaned and surface activation pretreatment;Next, the glaze is accurately printed on the surface of the barrel to form a scale pattern by silk screen printing;Finally, it is sintered in stages, including low-temperature drying, degassing, high-temperature melting and slow cooling stages, so that the glaze and the glass matrix are fused to form a permanent scale.The application also relates to a glass syringe made by the method.The scale line prepared by the method has excellent properties such as strong adhesion, wear resistance, chemical corrosion resistance and high-pressure sterilization, and the process is environmentally friendly and efficient, suitable for automated production.

Description

Technical Field

[0001] This invention relates to the field of medical device manufacturing technology, specifically to a curing method for forming permanent, high-precision graduation lines on a glass syringe, and a glass syringe product with excellent durability obtained by this method. Background Technology

[0002] Glass syringes remain irreplaceable in high-end medical and laboratory analysis fields due to their excellent chemical inertness, high-temperature resistance, and dimensional stability. The graduations on them are crucial for ensuring accurate dosage. Traditional graduation methods, such as acid etching, while providing durable graduations, are complex, environmentally polluting, and inefficient. Ordinary ink printing methods, on the other hand, have poor adhesion, are susceptible to wear and tear from solvents like alcohol and repeated sterilization, posing medical risks.

[0003] Therefore, there is an urgent need for a high-efficiency processing method that can ensure clear and accurate scales while being suitable for automated and clean production. Summary of the Invention

[0004] This invention provides a method for curing the graduation lines of a glass syringe, comprising the following steps: This invention provides a method for curing graduation lines on a glass syringe. The core of this method lies in preparing a special glass enamel, printing it onto a glass substrate, and then using a precisely controlled high-temperature sintering process to melt the enamel and chemically bond it with the glass substrate at the interface, thereby achieving permanent curing of the graduations. The method specifically includes the following steps: S1. Glaze preparation: Lead-free low-melting-point glass powder, inorganic pigments and organic carriers are mixed in a predetermined ratio, and then fully ground and dispersed to form a glaze slurry with uniform composition and suitable rheological properties for printing.

[0005] S2. Substrate pretreatment: Thoroughly clean the glass syringe barrel with physical and chemical methods, and use surface activation technology to improve its surface energy, so as to greatly enhance the wettability and adhesion of subsequent glazes.

[0006] S3. Pattern printing: Using high-precision screen printing technology, the glaze prepared in step S1 is precisely transferred to a predetermined position on the outer surface of the cylinder activated in step S2 to form the required scale lines and numerical patterns.

[0007] S4. High-temperature sintering: The printed product is placed in a programmable temperature-controlled furnace for segmented heat treatment. Through precisely controlled heating, holding, and cooling processes, the organic carrier is completely decomposed and volatilized, and the glass powder particles in the glaze melt, flow, and finally form a strong chemical bond with the glass matrix at the interface. After cooling, a finished product with permanent graduation lines is obtained.

[0008] As a further preferred embodiment of the method of the present invention: In step S1, the softening point temperature of the lead-free low-melting-point glass powder is preferably between 500°C and 650°C. Its particle size distribution needs to be finely controlled, with a D50 of 1-5 μm and a D90 of no more than 10 μm. Excessively fine powder is prone to agglomeration, while excessively coarse powder affects printing accuracy and surface finish after sintering. More preferably, the glass powder is a borosilicate system, containing at least one of zinc oxide (ZnO), boric anhydride (B2O3), and phosphate as a highly efficient flux to effectively reduce its melting temperature without using toxic heavy metals such as lead, ensuring good flowability below the deformation point of the base glass.

[0009] In step S1, the inorganic pigment is used to provide the contrasting color required for the scale. Preferably, it is at least one metal oxide or a composite oxide selected from iron oxide (providing red / brown / yellow), copper oxide (providing blue / green), and manganese oxide (providing brown / black). The pigment particle size D50 is preferably 0.5-2 μm to ensure uniform dispersion in the glaze and color stability without color change at high temperatures.

[0010] In step S1, the organic carrier serves to provide rheological properties suitable for screen printing and temporarily bind solid particles before sintering. Its typical composition includes: a solvent, such as terpineol, to provide flowability; a binder, preferably ethyl cellulose, at a content of 5-8 wt% in the organic carrier, to provide cohesion; and a plasticizer, preferably a phthalate compound such as dibutyl phthalate, at a content of 2-4 wt%, to improve flexibility. By adjusting the composition, the viscosity of the final glaze at 25°C is controlled within the range of 30,000-40,000 cP to obtain optimal printability.

[0011] In step S2, the cleaning process aims to remove contaminants such as grease and dust. A preferred procedure is as follows: ultrasonic cleaning for 5-15 minutes at 40-60°C using a neutral or weakly alkaline cleaning agent (such as a 1-3% sodium dodecylbenzenesulfonate solution); followed by rinsing with plenty of deionized water; then ultrasonic cleaning with anhydrous ethanol to remove residual moisture and organic impurities; and finally, thorough drying in an oven at 80-100°C.

[0012] The surface activation treatment is a crucial step, aiming to further break down the inertia of the glass surface and introduce active groups on top of cleaning. Low-temperature oxygen plasma treatment or ultraviolet ozone treatment is preferred. The preferred parameters for oxygen plasma treatment are: power 100-200 W, oxygen flow rate 50-150 sccm, and treatment time 60-120 seconds. The preferred parameters for ultraviolet ozone treatment are: using ultraviolet lamps with dominant wavelengths of 185 nm and 254 nm, treatment time 10-30 minutes, and maintaining the ozone concentration in the treatment chamber above 50 mg / m³. Both treatments effectively increase the density of hydroxyl (-OH) groups on the glass surface, significantly improving the spreadability and initial adhesion of the glaze.

[0013] In step S3, the screen printing process parameters need to be precisely controlled to ensure pattern accuracy. Preferably, a 400-600 mesh polyester or stainless steel screen is used, with the screen tension controlled at 20-25 N / cm to maintain screen flatness. During printing, the glass syringe barrel is axially fixed to a uniformly rotating fixture, with the rotation speed set at 10-30 rpm to ensure the enamel is transferred evenly and continuously to the circumferential surface. A polyurethane squeegee with a hardness of 70-80 Shore A is preferred, with the squeegee angle set at 60-70° and the printing pressure at 0.3-0.5 MPa. The printing environment should be controlled at a temperature of 20-25℃ and a relative humidity of 40-60% RH to ensure stable rheological properties of the enamel.

[0014] In step S4, the segmented heat treatment is crucial for forming permanent chemical bonds and must be carried out in an air atmosphere to prevent the reduction reaction from affecting the color. Specifically, it includes four precisely controlled stages: S41. Low-temperature drying stage: Raise the temperature from room temperature to 150-180℃ at a slow heating rate (2-5℃ / min) and hold for 10-15 minutes. This stage allows the solvent in the organic carrier to evaporate slowly and evenly, avoiding blistering or cracking of the glaze layer due to rapid vaporization.

[0015] S42, Debinding Stage: Raise the temperature to 350-380℃ at a slightly faster rate (3-5℃ / min) and hold for 5-10 minutes. This stage allows the remaining organic binders and plasticizers to fully decompose, carbonize, and oxidize into gases (such as CO2 and H2O). These gases are then thoroughly removed by maintaining air circulation within the furnace (e.g., wind speed of 0.5-1.0 m / s) to prevent carbon residue from causing discoloration or bubbles.

[0016] S43. High-temperature melting stage: The temperature is increased to 580-630℃ at a rate of 2-4℃ / min. This temperature is higher than the softening point of the glaze glass powder but much lower than the deformation point (typically >700℃) of a high-quality syringe glass substrate (such as neutral borosilicate glass), and held for 10-15 minutes. At this temperature, the glass powder particles completely melt, spread, and flow, undergoing interdiffusion and chemical reaction with the substrate glass surface to form a strong interfacial bonding layer mainly composed of covalent bonds such as Si-O-Si and Si-OB.

[0017] S44. Slow Cooling Stage: Control the cooling rate (2-4℃ / minute) to lower the furnace temperature to below 150℃, then turn off the heating and allow it to cool naturally to room temperature. This process aims to eliminate internal stress caused by the slight difference in the coefficients of thermal expansion between the glaze and the substrate, as well as temperature gradients, preventing product cracking or micro-cracks in the glaze layer.

[0018] Secondly, the present invention provides a glass syringe. The syringe is characterized in that the permanent graduation lines on the outer surface of its barrel are prepared by the method described in the first aspect of the invention. The graduation lines become part of the glass body, rather than a surface coating.

[0019] As a further preferred embodiment of the product of the present invention: The glass syringe barrel is preferably made of borosilicate glass with a heat resistance temperature above 700°C, such as neutral borosilicate glass conforming to ISO 1101-1. This material ensures that the barrel itself does not soften or deform during the high-temperature melting stage of the glaze (580-630°C).

[0020] The width of the graduation lines can be precisely controlled within the range of 0.1-0.2 mm, and the edges of the lines are sharp. The graduation lines and the glass substrate are chemically bonded together through the above-mentioned high-temperature melting process, and the bonding strength is much higher than that of physical adsorption or mechanical intercalation.

[0021] (III) Beneficial Effects Compared with the prior art, the present invention has the following significant advantages: Improved graduation performance: This invention solves the problem of poor adhesion of traditional ink graduations. Through high-temperature chemical bonding between the glaze and the substrate, the graduation lines are fused with the glass, exhibiting excellent adhesion, abrasion resistance, and chemical resistance. It can withstand high-pressure steam sterilization, meeting stringent medical sterilization requirements.

[0022] Excellent biocompatibility and stability: The final scale is composed of only lead-free glass and inorganic oxide pigments, which are chemically stable, have no risk of organic leaching, do not react with drugs, have excellent biocompatibility, and meet the requirements of major global pharmacopoeias such as FDA, EP, and ChP for packaging materials that come into direct contact with pharmaceuticals.

[0023] Appearance: The scale lines are fine (up to 0.1mm), with clear edges and regular characters. The glaze is smooth and glossy, with high visual contrast, which greatly improves the accuracy and convenience of dose reading.

[0024] Production process: The entire process eliminates hazardous chemicals such as hydrofluoric acid. The main waste gases are CO2 and water produced by the decomposition of organic carriers, which can be treated by simple combustion. The environmental impact is small and the production safety risk is low. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0027] Example 1: Preparation of a 1mL glass syringe with blue graduations This embodiment details the process of preparing a small-capacity precision glass syringe using the method of the present invention.

[0028] S1. Glaze preparation: Formula (based on 100g of total glaze slurry mass): 68g of lead-free low-melting-point borosilicate glass powder with a softening point of 580±10℃, containing 12 wt% ZnO and 8 wt% B2O3 as composite flux.

[0029] Inorganic pigment: Copper oxide (CuO), 3g. Purity ≥99.5%, particle size D50=1.2 μm.

[0030] Organic carrier: 27g. Preparation method: Dissolve 1.62g ethyl cellulose (EC-N50) and 0.81g dibutyl phthalate (DBP) in 24.57g terpineol and stir until completely transparent and homogeneous.

[0031] Preparation process: The glass powder, pigment, and organic carrier were placed together in a 500mL zirconia ball mill jar, and 300g of zirconia grinding balls (a mixture of 3mm and 5mm diameter balls) were added. The mixture was ball-milled at 300 rpm for 8 hours in a planetary ball mill. After discharge, the mixture was filtered through a 400-mesh (approximately 38μm pore size) nylon sieve to obtain a fine and uniform glaze. The viscosity was measured using a rotational viscometer (Brookfield DV2T) at 25℃, spindle speed 52, and 20 rpm, and was found to be 35,200 cP.

[0032] S2. Matrix pretreatment: Matrix: Neutral borosilicate glass conforming to ISO 1101-1 is used to make the 1mL syringe barrel.

[0033] Cleaning: Immerse the cylinder body in a 2% sodium dodecylbenzenesulfonate aqueous solution and clean it in a 50℃ ultrasonic cleaner (40kHz) for 10 minutes. Rinse three times with running deionized water. Then immerse it in anhydrous ethanol and ultrasonically clean it for 10 minutes. After removing it, place it in a 100℃ circulating air oven to dry for 30 minutes.

[0034] Surface activation: The dried cylinder was placed into the reaction chamber of a flat-plate oxygen plasma cleaner (model: PTL-200). Parameters were set as follows: RF power 150W, oxygen flow rate 100 sccm, chamber pressure 50 Pa, treatment time 90 seconds. After treatment, the surface water contact angle decreased from approximately 40° after cleaning to <10°, indicating a significant improvement in hydrophilicity.

[0035] S3, Pattern Printing: Screen printing: A 500-mesh yellow polyester screen is used, with a tension of 22 N / cm. High-precision laser direct printing technology is employed to create precise graduation lines and numerical patterns from 0.01 mL to 1.00 mL on the screen, with a minimum line width of 0.1 mm.

[0036] Printing Setup: Clamp the activated cylinder onto the mandrel of a dedicated rotary printing press, ensuring coaxiality. Set the mandrel rotation speed to 20 rpm. Select a polyurethane squeegee with a Shore A hardness of 75A (dimensions: 150mm × 20mm × 10mm), set the installation angle to 65 degrees, and adjust the printing pressure to 0.40 MPa via a cylinder. Maintain the printing workshop environment at 23±1℃ and 50±3% RH relative humidity.

[0037] Printing Operation: Place an appropriate amount of enamel on the screen and start the equipment. The squeegee pushes the enamel at a uniform speed. In the contact area between the screen and the rotating cylinder surface, the enamel is precisely deposited onto the cylinder surface through the mesh, forming a wet scale pattern. After printing, visually inspect the pattern; it should be continuous and complete, without broken lines, jagged edges, or smudging.

[0038] S4, High-temperature sintering: Place the printed cylinder horizontally on a high-temperature alloy tray with an aluminum oxide coating on its surface, ensuring that they do not touch each other.

[0039] Push the tray into the temperature-controlled muffle furnace.

[0040] Perform the following sintering procedure: Low-temperature drying: Increase the temperature from room temperature to 180℃ at a rate of 3℃ / min and hold for 10 min.

[0041] Glue removal: Increase the temperature to 380℃ at a rate of 4℃ / min and hold for 8 minutes. During this time, slightly open the furnace door by about 5mm and turn on the exhaust fan on the top of the furnace.

[0042] High-temperature melting: Heat to 620℃ at a rate of 3℃ / min and hold for 12 minutes. Close the furnace door, and allow natural air atmosphere (oxygen content of approximately 21%) inside the furnace.

[0043] Slow cooling: After sintering, turn off the heating power and utilize the furnace's own insulation properties to cool it down at an average rate of approximately 4°C / min for the first hour. When the furnace temperature drops to 150°C, fully open the furnace door to accelerate cooling to near room temperature before removing the product.

[0044] The prepared glass syringe samples were tested: Appearance: The scale lines are blue, with clear and sharp edges, and no burrs, broken lines or diffusion.

[0045] Adhesion test: The cross-cut test (1mm spacing) was performed according to ISO 2409 standard. After applying 3M tape and pulling hard, if no graduations came off, the grade was rated as 0.

[0046] Abrasion resistance test: Rub the graduated line 1000 times with a 500g-loaded eraser, and there is no visible wear on the graduated line.

[0047] Chemical resistance test: After immersing the sample in 75% alcohol for 72 hours, the scale line remains unchanged after vigorous wiping.

[0048] Sterilization resistance test: After 30 cycles of high-pressure steam sterilization at 121℃ for 30 minutes, the graduation lines remained intact, without discoloration or peeling.

[0049] Conclusion: This embodiment successfully prepared a glass syringe with extremely excellent calibration performance. Its various indicators far exceed those of traditional ink-printed products, and it reaches or even surpasses the durability level of acid-etched products. Moreover, the production process is environmentally friendly and efficient.

[0050] Example 2: Preparation of a 10mL glass syringe with brown graduations This embodiment illustrates a process for continuous production in a tunnel furnace.

[0051] S1. Glaze preparation: Formula (based on 100g of total glaze slurry mass): Lead-free borosilicate glass powder: 70g. Softening point 560±5℃; contains 10 wt% ZnO and 5 wt% B2O3 as composite flux; particle size: D50=2.8 μm, D90=8.9 μm.

[0052] Brown inorganic pigment: 5g. It is a physical mixture of iron oxide red (Fe2O3) and copper oxide (CuO) at a mass ratio of 1:1, with a D50 of 1.6 μm.

[0053] Organic carrier: 25g. Contains 7 wt% ethyl cellulose and 2 wt% DBP, with terpineol as the solvent.

[0054] The mixture was ball-milled for 6 hours (ball-to-material ratio 2.5:1) and passed through a 500-mesh sieve to obtain a brown glaze with a viscosity of 38,500 cP.

[0055] S2. Matrix pretreatment: Matrix: 10mL neutral borosilicate glass syringe barrel.

[0056] Cleaning: The automated cleaning line completes the process, which is the same as in Example 1.

[0057] Surface activation: An online ultraviolet ozone treatment device is used. The cylinder passes through the treatment chamber via a conveyor belt. 185 / 254 nm ultraviolet lamps are arranged in the chamber. The treatment time is set to 25 minutes, and the ozone concentration is monitored to be >80 mg / m³.

[0058] S3, Pattern Printing: Screen: 480 mesh stainless steel wire mesh, tension 24 N / cm, pattern line width 0.15 mm.

[0059] Printing: Rotation speed 18 rpm, squeegee angle 68°, pressure 0.38 MPa. Environmental control as before.

[0060] S4, High-temperature sintering: After printing, the cylinder is automatically placed on a heat-resistant ceramic conveyor belt and passes sequentially through four independently temperature-controlled furnace zones: Drying zone: Set temperature 175℃, conveyor belt speed allows products to remain in place for approximately 15 minutes.

[0061] Glue discharge area: set temperature 375℃, stay for about 8 minutes, this area is equipped with a strong exhaust duct at the top.

[0062] Melting zone: Set temperature 605℃, hold for about 18 minutes.

[0063] Slow cooling zone: This zone is about 5 meters long. The temperature is gradually reduced from 600℃ to about 200℃ through multiple temperature control stages, with an average cooling rate of about 3℃ / min.

[0064] The product is cooled to room temperature after being taken out of the oven.

[0065] Performance testing: Performance Tests and Results: The prepared glass syringe samples were tested, and the results are as follows: Appearance: The scale lines are a uniform brownish-red, with a rich color, continuous and clear lines, and no broken lines or smudging.

[0066] Adhesion test: The cross-cut test (1mm spacing) was performed according to ISO 2409 standard. After applying 3M tape and pulling hard, if no graduations came off, the grade was rated as 0.

[0067] Abrasion resistance test: After rubbing the scale line with a 500g-loaded eraser 1500 times, there was no visible wear on the scale line.

[0068] Chemical resistance test: After immersing the sample in 0.5% sodium hypochlorite disinfectant for 24 hours, the scale line showed no change when vigorously wiped.

[0069] Sterilization resistance test: After 50 cycles of high-pressure steam sterilization at 121℃ for 30 minutes, the graduation lines remained intact, without discoloration or peeling, demonstrating excellent durability.

[0070] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, and the existence of an infinite number of specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A method for curing the graduation lines of a glass syringe, characterized in that, Includes the following steps: S1. Glaze preparation: Lead-free low-melting-point glass powder, inorganic pigments and organic carriers are mixed in proportion, and then ground and dispersed to form a homogeneous glaze. S2. Substrate pretreatment: Cleaning and surface activation treatment of the glass syringe barrel; S3. Pattern printing: The glaze prepared in step S1 is precisely printed onto the outer surface of the cylinder after step S2 using screen printing technology to form a scale pattern. S4. High-temperature sintering: The printed glass syringe is subjected to segmented heat treatment, which melts the glass powder in the glaze and forms a chemical bond with the glass substrate of the syringe body. After cooling, a glass syringe with permanent scale lines is obtained.

2. The method for curing the graduation lines of a glass syringe according to claim 1, characterized in that: In step S1, the softening point temperature of the lead-free low-melting-point glass powder is 500℃ to 650℃, and the particle size distribution is D50: 1-5 μm, D90: ≤10 μm.

3. The method for curing the graduation lines of a glass syringe according to claim 2, characterized in that: The lead-free low-melting-point glass powder is a borosilicate glass powder, which contains at least one selected from zinc oxide (ZnO), boron anhydride (B2O3), and phosphate as a flux.

4. The method for curing the graduation lines of a glass syringe according to claim 1, characterized in that: In step S1, the inorganic pigment is at least one metal oxide or a composite oxide selected from iron oxide, copper oxide, and manganese oxide, and its particle size D50 is 0.5-2 μm.

5. The method for curing the graduation lines of a glass syringe according to claim 1, characterized in that: In step S1, the organic carrier comprises a solvent, a binder, and a plasticizer; wherein the binder is ethyl cellulose, and its content in the organic carrier is 5-8 wt%; the plasticizer is a phthalate compound, and its content in the organic carrier is 2-4 wt%; the viscosity of the glaze at 25°C is 30,000-40,000 cP.

6. The method for curing the graduation lines of a glass syringe according to claim 1, characterized in that: In step S2, the cleaning process includes: ultrasonic cleaning with a neutral cleaning agent at 40-60°C, followed by rinsing with deionized water and anhydrous ethanol in sequence, and drying at 80-100°C; the surface activation treatment is low-temperature oxygen plasma treatment or ultraviolet ozone treatment.

7. The method for curing the graduation lines of a glass syringe according to claim 6, characterized in that, The process parameters for the oxygen plasma treatment are: power 100-200 W, oxygen flow rate 50-150 sccm, and treatment time 60-120 seconds; the process parameters for the ultraviolet ozone treatment are: using ultraviolet light with wavelengths of 185 nm and 254 nm, treatment time 10-30 minutes, and ozone concentration in the treatment environment ≥50 mg / m³.

8. The method for curing the graduation lines of a glass syringe according to claim 1, characterized in that, In step S3, the screen printing uses a 400-600 mesh polyester or stainless steel wire mesh with a wire mesh tension of 20-25 N / cm. During printing, the glass syringe barrel rotates at a speed of 10-30 rpm, a polyurethane squeegee is used with a squeegee angle of 60-70°, and the printing pressure is 0.3-0.5 MPa.

9. The method for curing the graduation lines of a glass syringe according to claim 8, characterized in that, In step S4, the segmented heat treatment is carried out in an air atmosphere, specifically including: S41. Low-temperature drying stage: Increase the temperature from room temperature to 150-180℃ at a rate of 2-5℃ / minute, and keep it at that temperature for 10-15 minutes. S42, Degreasing stage: Raise the temperature to 350-380℃ at a rate of 3-5℃ / minute, hold for 5-10 minutes, and keep the air circulating inside the oven; S43. High-temperature melting stage: Heat to 580-630℃ at a heating rate of 2-4℃ / min, and hold for 10-15 minutes; S44. Slow cooling stage: Control the furnace temperature to drop below 150℃ at a cooling rate of 2-4℃ / minute, and then allow it to cool naturally to room temperature.

10. A glass syringe, characterized in that, The permanent scale lines on its outer surface are prepared by the method described in any one of claims 1 to 9.