An optical lens processing process

Abstract

The present application relates to the technical field of lens processing, and particularly relates to an optical lens processing technology, which comprises the following steps: S1, resin base material is subjected to ultrasonic treatment, stearic amide is added, a curing agent is injected into the resin base material, and the curing agent and the resin base material are uniformly mixed by ultrasonic vibration and screw pushing; S2, the mixed material is injected into a mold and heated to 65-81 DEG C for preliminary curing, when the lens reaches a preset hardness or a preset curing time, the temperature is reduced by 15-20 DEG C and maintained; then the temperature is increased to 115-121 DEG C for final curing, after the final curing is completed, the temperature is reduced to 5-10 DEG C below the resin glass transition temperature, a gap is formed by slightly opening the mold, and nitrogen is introduced; S3, after the mold is cooled to 59-61 DEG C, compressed air pulses are injected into the mold parting surface; the problems of poor optical performance, low size precision and high scrap rate of the lens caused by uneven dispersion of the curing agent, curing stress concentration and demolding damage in the existing optical lens processing technology are overcome.

Description

Technical Field

[0001] This invention relates to the field of lens processing technology, and more particularly to an optical lens processing technology. Background Technology

[0002] Optical resin lenses are widely used in eyeglasses, optical instruments and other fields due to their advantages such as light weight, good impact resistance and low processing cost. The core of their processing technology lies in the uniform mixing of resin base material and curing agent, controllable curing and non-destructive demolding, which directly affects the optical and mechanical properties of the lens. The optical properties are mainly reflected in the uniformity of light transmittance and refractive index, while the mechanical properties are mainly reflected in hardness and resistance to yellowing.

[0003] In existing technologies, the mixing of resin base material and curing agent mostly relies on mechanical stirring. However, the large particle size of the curing agent can easily lead to uneven local curing reaction, affecting the refractive index stability of the lens. Furthermore, mechanical stirring can easily introduce air bubbles, requiring an additional degassing process and extending the processing cycle. Some processes have attempted to introduce ultrasonic-assisted mixing, but the improvement in dispersion efficiency is limited.

[0004] The demolding process also faces numerous challenges. Traditional methods often rely on mechanical ejection, manual peeling, or the use of a single internal release agent. However, mechanical ejection can easily cause scratches and edge cracks on the lens surface, especially for complex curved or thin lenses, where the risk of damage is even higher. Manual peeling is not only inefficient but also makes it difficult to ensure uniform force, easily causing lens deformation. While the use of a single internal release agent can reduce demolding difficulty to some extent, smooth demolding is still difficult when the resin lens is tightly fitted to the mold cavity and the shrinkage rate after curing is small, often requiring additional external force, which also affects lens quality. Some processes attempt to introduce auxiliary methods during curing, but existing curing process designs mostly focus on improving curing speed and lens hardness, with insufficient consideration for the correlation between the curing stage and demolding effect. Therefore, there is an urgent need for an optical lens processing technology that can achieve ultra-fine dispersion of the curing agent, precise control of curing stress, and automatic, non-destructive demolding to improve product quality and production efficiency.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an optical lens processing technology that overcomes the problems of poor optical performance, low dimensional accuracy and high scrap rate of existing optical lens processing technologies caused by uneven dispersion of curing agent, concentrated curing stress and demolding damage.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An optical lens processing technology includes:

[0009] S1. The resin base is ultrasonically treated to a microfluidic state, and 0.2~0.4wt% stearamide is added and dispersed evenly. The curing agent is injected into the resin base through a screw pump. The curing agent is dispersed into microdroplets ≤10μm by the synergistic effect of ultrasonic vibration and screw pushing and is evenly mixed with the resin base. The mixture is discharged through a buffer tank.

[0010] In this step, stearamide, accounting for 0.2-0.4% of the resin matrix by mass, is added uniformly to the resin matrix under an ultrasonic environment. As an internal release agent, the hydrophobic long chains in the stearamide molecular structure can be rapidly dispersed under the shear force generated by ultrasonic vibration, forming tiny particles of 1-3 μm that are uniformly embedded in the resin matrix. At the same time, ultrasonic vibration promotes the formation of weak interactions between stearamide molecules and the polar groups of the resin matrix, which not only ensures dispersion stability but also lays the foundation for its directional migration to the interface between the resin lens and the mold in the subsequent curing stage. Thus, a low surface energy interface layer is pre-constructed without affecting the optical properties of the resin.

[0011] The amount of stearamide added is 0.2~0.4wt% of the resin base, which provides a sufficient material basis for the directional migration to the interface between the resin lens and the mold during the curing stage, and avoids uneven dispersion in the resin due to excessive addition, or affects the optical and mechanical properties of the resin.

[0012] After the stearamide is mixed evenly, the curing agent is injected into the resin base through a precision screw pump. The precision screw pump delivers the curing agent from the storage tank to the inside of the mixing tank, controlling the flow rate of the curing agent with an accuracy of ±0.1mL / min, so that the ratio of the base material to the curing agent strictly meets the process requirements. When the curing agent enters the resin base, it is immediately subjected to high-frequency vibration of the ultrasonic vibrator at the bottom of the mixing tank. The cavitation effect generated by the ultrasonic waves tears the curing agent liquid into microdroplets ≤10μm. The linear power of the continuous push of the screw pump will quickly carry these microdroplets into the depth of the resin base, avoiding accumulation near the inlet. At this time, the helical push of the screw pump and the high-frequency vibration of the ultrasonic waves are coupled, which significantly improves the uniformity of the curing reaction and achieves uniform mixing compared with the 20~50μm curing agent droplets in the prior art.

[0013] The amount of curing agent added is 2-4% of the weight of the resin base. The above-mentioned amount of curing agent provides sufficient active centers for the free radical polymerization of the resin base, ensuring that the resin forms a stable and uniform cross-linked network, meeting the requirements of the lens for mechanical properties such as hardness and anti-yellowing, and also avoiding excessive local curing reaction due to excessive addition, resulting in internal stress concentration or lens embrittlement.

[0014] S2. Inject the mixture into the mold and heat it to 65~81℃ for initial curing. When the lens reaches the preset hardness or preset curing time, cool it down by 15~20℃ and maintain it for 2~4 minutes. Then heat it up to 115~121℃ for final curing. After final curing, cool it down to 5~10℃ below the glass transition temperature of the resin, control the mold to open slightly to form a gap and introduce nitrogen gas.

[0015] This step employs a stepped curing process, achieving precise control over complete resin cross-linking and interfacial adhesion through phased control of initial curing, cooling relaxation, final curing, and cooling pre-separation. First, initial heating curing and cooling relaxation allow the resin to form a stable cross-linked network to ensure mechanical properties, while simultaneously promoting stearamide migration to the interface to form a low surface energy layer. After final curing, the temperature is lowered to the glass transition temperature, and nitrogen gas is introduced through micro-opening of the mold. Pre-separation is achieved using resin shrinkage and the nitrogen gas cushion, reducing the adhesion between the resin lens and the mold and solving the problem of insufficient correlation between curing and demolding.

[0016] S3. After the mold cools to 59~61℃, inject compressed air pulses into the mold parting surface to separate the resin lens from the mold and allow it to fall off automatically.

[0017] This step achieves non-destructive separation of the resin lens from the mold through the synergistic effect of gradient cooling and stepped air pressure separation. The mold is cooled to 59~61℃ to fix the shape of the lens and stabilize the gap. By injecting stepped compressed air pulses into the parting surface, the residual adhesion is overcome uniformly by the low surface energy interface layer, which pushes the resin lens to separate from the mold, avoiding damage such as scratches or cracks caused by mechanical ejection or manual peeling, thus achieving efficient and non-destructive demolding.

[0018] As a preferred embodiment of the present invention, the resin base is any one of MR-8 resin, MR-10 resin or CR-39 resin, and the curing agent is at least one of benzoyl peroxide and tert-butyl hydroperoxide.

[0019] The aforementioned resin base material possesses excellent light transmittance, mechanical strength, and molding properties, and can serve as a high-quality substrate to provide a fundamental guarantee for the optical and mechanical properties of lenses.

[0020] The aforementioned curing agent not only possesses the activity of initiating free radical polymerization of resin base materials, but also promotes the formation of a stable cross-linked network in the resin to ensure the mechanical properties of the lens, such as hardness.

[0021] Among them, the viscosity of benzoyl peroxide is 10~20 mPa·s, and the viscosity of tert-butyl hydroperoxide is 20~30 mPa·s;

[0022] The viscosity range described above is compatible with the synergistic effect of ultrasonic vibration and screw pushing in step S1. Under the tearing effect of ultrasonic cavitation and the diffusion effect of screw pushing, it can be effectively dispersed into microdroplets of ≤10μm, ensuring uniform mixing of the curing agent and resin base material and avoiding uneven local curing reaction caused by excessively large dispersed particles.

[0023] As a preferred embodiment of the present invention, in step S1, when the resin base material is subjected to ultrasonic treatment alone, the ultrasonic frequency is 20~25kHz, the power is 150~300W, and the duration is 3~5min.

[0024] The resin base material is subjected to separate ultrasonic treatment. Specifically, the resin base material is injected into a mixing tank, and the ultrasonic vibrator at the bottom of the tank is turned on. The resin base material is continuously treated using an ultrasonic frequency of 20~25kHz and a power of 150~300W. This causes the resin base material molecular chains to relax under the vibration, presenting a microfluidic state and improving fluidity. To further reduce the viscosity of the resin base material and enhance the ultrasonic dispersion effect, the mixing tank can be kept warm in a water bath at a temperature of 40~50℃, which is adjusted according to the type of resin. For example, 45℃ is preferred for CR-39 resin.

[0025] Then, under continuous ultrasonic conditions, stearamide is added at a constant speed until dispersed. After injecting the curing agent, the ultrasonic frequency is adjusted to 25~30kHz, the power is increased to 300~400W, and it works in conjunction with the screw push for 2~3 minutes.

[0026] Continuous ultrasound can rapidly disperse stearamide into tiny particles of 1~3μm through shear force, while simultaneously promoting weak interactions between stearamide and the polar groups of the resin matrix. This ensures dispersion stability and lays the foundation for subsequent directional migration to the resin lens and mold interface. Furthermore, enhancing the ultrasound parameters after injecting the curing agent can strengthen the cavitation effect and shear force of the ultrasound. Combined with the power of the screw push, this ensures that the curing agent is effectively torn into droplets ≤10μm and uniformly mixed, avoiding local aggregation and solving the problem of uneven local curing caused by the large particle size of the curing agent in the prior art.

[0027] As a preferred embodiment of the present invention, in step S1, the discharge port of the screw pump is located 5-10 mm below the surface of the resin base liquid, and the discharge direction is consistent with the direction of the wave crest of the ultrasonic vibration.

[0028] This position allows the curing agent to be directly in the ultrasonic vibration zone immediately after injection, preventing air bubbles from being introduced when the curing agent is exposed above the liquid surface. The discharge direction, which is consistent with the wave crest direction, allows the curing agent flow to be precisely superimposed on the energy concentration area of ​​the ultrasonic vibration, maximizing the tearing effect of ultrasonic cavitation. This ensures that the curing agent is initially dispersed the moment it enters the base material, laying the foundation for subsequent uniform mixing in conjunction with the screw push.

[0029] When the viscosity of the curing agent is 10~20 mPa·s, and the ultrasonic power is 300W, the corresponding pushing rate is 4~6 mL / min;

[0030] When the viscosity of the curing agent is 20~30 mPa·s, and the ultrasonic power is 300W, the corresponding pushing rate is 6~8 mL / min;

[0031] During the process, for every 50W increase in ultrasonic power, the pushing rate increases by 1~2mL / min.

[0032] For low-viscosity curing agents, a lower push rate can avoid insufficient dispersion caused by excessively fast liquid flow, and effective tearing can be achieved with 300W ultrasonic power. For high-viscosity curing agents, a higher push rate can overcome viscous resistance and ensure that they are fully carried into the base material at the same ultrasonic power. When the ultrasonic power is increased, the push rate is increased simultaneously, which can further enhance the coupling effect of energy and power, and ultimately enable curing agents of different viscosities to be stably dispersed into droplets ≤10μm.

[0033] As a preferred embodiment of the present invention, in step S1, the buffer tank is a vertical cylindrical structure, and a vacuum extraction port is provided at the top of the tank to maintain a slight negative pressure of -0.005 to -0.01 MPa; the residence time of the mixture in the buffer tank is 0.5 to 1 min, and a diffusion cone with a cone angle of 60° to 90° is provided at the inlet.

[0034] More specifically, the vertical cylindrical flow channel can guide the mixture to form a stable laminar flow state, avoiding turbulent disturbances caused by irregular structure, thereby reducing the risk of coagulation of curing agent droplets during the flow process. At the same time, it facilitates the uniform and continuous output of the mixture to the mold, preventing defects such as flow lines or uneven density caused by flow rate fluctuations.

[0035] The micro-negative pressure environment at the top of the tank can promote the rise and escape of tiny air bubbles in the mixture. Combined with the residence time of the buffer tank, it can achieve efficient defoaming, solving the problem that mechanical stirring can easily introduce air bubbles and requires an additional defoaming process in the existing technology. At the same time, it avoids excessive negative pressure from causing the base material to volatilize or change its composition.

[0036] The aforementioned residence time provides sufficient time for the curing agent droplets to homogenize, ensuring further uniform dispersion in laminar flow and offsetting the risk of localized coalescence after ultrasonic cessation. It also avoids premature curing of the mixture due to excessive residence time.

[0037] More specifically, the diffusion cone diffuses in an inverted cone shape from bottom to top, and then the inner diameter remains unchanged. The flow direction of the mixture is from bottom to top. The diffusion cone set at the inlet can buffer and diffuse the mixture flow entering the buffer tank, reduce the flow velocity and impact force at the inlet, avoid local turbulence from disrupting the laminar flow state, and at the same time allow the mixture to be more evenly distributed on the cross-section of the buffer tank, improving the homogenization and defoaming effect.

[0038] As a preferred embodiment of the present invention, in step S2, the preset hardness is Shore D hardness 35±2. Within the above hardness range, the resin has a certain structural stability, which can support the subsequent cooling relaxation and final curing steps. At the same time, the incompletely cured state allows the molecular chains to undergo stress relaxation during the cooling process, reducing internal stress concentration. Furthermore, at the above hardness, stearamide molecules can still migrate to the resin-mold interface through thermal motion, creating conditions for constructing a low surface energy interface layer and avoiding the obstruction of mold release agent migration due to over-curing, which would affect the subsequent mold release effect.

[0039] As a preferred embodiment of the present invention, in step S2, the preset curing time is 450~500s. The above-mentioned time allows the resin base material to fully undergo free radical polymerization in the initial curing stage at 65~81℃, achieving the crosslinking degree required for the preset hardness. This avoids insufficient crosslinking and poor structural stability caused by too short a time, and also prevents the resin from being over-cured due to too long a time, which would make it difficult to release internal stress during subsequent cooling and relaxation. At the same time, it provides sufficient migration time for stearamide molecules to initially form an interface layer.

[0040] As a preferred embodiment of the present invention, in step S2, the surface roughness Ra of the mold cavity is ≤0.02μm, and the inner wall of the cavity is silanized, with a surface tension ≤20mN / m. The low surface roughness can reduce the mechanical engagement points between the cavity and the resin, and reduce the physical adhesion. The surface tension of the inner wall of the cavity after silanization treatment is ≤20mN / m, which can significantly weaken the intermolecular forces between the resin lens and the mold. The synergistic effect of the two can reduce the bonding force between the resin lens and the mold, laying the foundation for smooth demolding and avoiding demolding damage caused by high interfacial adhesion in traditional processes.

[0041] After final curing, the gap of the micro-mold is 0.3~0.5mm, the opening and closing speed is controlled at 0.05~0.1mm / s, the temperature of the introduced nitrogen is the same as the current temperature of the mold, the flow rate is 3~5L / min, the introduction time is 10~12s, and the moisture content in the nitrogen is ≤0.01%.

[0042] More specifically, the aforementioned gap size provides sufficient space for nitrogen injection to form a stable air cushion, while preventing excessive gaps that could cause lens deformation under gravity. The slow opening and closing speed prevents the transmission of instantaneous stress generated by rapid mold movement to the lens, maintaining structural stability during the pre-separation stage and reducing the risk of edge chipping. Nitrogen at the same temperature avoids uneven localized resin shrinkage or condensation caused by temperature differences, protecting the lens's optical performance. The aforementioned flow rate and injection time allow nitrogen to quickly fill the gaps and effectively remove residual oligomers, achieving effective pre-separation. Low moisture content prevents watermarks from forming on the lens surface, avoiding impact on optical indicators such as light transmittance.

[0043] In a preferred embodiment of the present invention, in step S2, the heating rate of the mold from room temperature to 65~81°C is 5~8°C / min, the cooling rate after initial curing is 1~5°C / min, the heating rate to 115~121°C is 3~5°C / min, and the temperature is maintained at 115~121°C for 15~20min. After final curing, the mold is cooled to 5~10°C below the glass transition temperature of the resin at a rate of 4~6°C / min. During the cooling process, the mold cavity is maintained at a slight positive pressure of 0.01~0.02MPa.

[0044] More specifically, step S2 achieves precise control over complete resin crosslinking and interfacial adhesion through stepwise regulation of initial curing, cooling relaxation, final curing, and cooling pre-separation. The specific process is as follows:

[0045] The uniformly mixed material in S1 is injected into the mold cavity that has been silanized. The mold is first heated from room temperature to 65-81°C at a rate of 5-8°C / min for preliminary curing. During this stage, the curing agent droplets in the resin base material initiate free radical polymerization under the action of heat, and the molecular chains grow rapidly to form a preliminary cross-linking network. At the same time, stearamide molecules slowly migrate to the interface between the resin and the mold due to thermal motion, and begin to build a low surface energy interface layer.

[0046] Once the preset hardness or curing time is reached, the mold is cooled down by 15-20°C at a rate of 1-5°C / min and maintained for 3-4 minutes. During the cooling process, the mobility of the resin molecular chains weakens, and the initially formed cross-linked network undergoes stress relaxation, reducing the internal stress concentration caused by rapid polymerization and avoiding the risk of cracking in subsequent processing. At the same time, due to the weakening of the weak interaction between stearamide and the polar groups of the resin at low temperatures, it is easier to detach from the resin phase. Therefore, the temperature reduction promotes the directional migration of stearamide molecules to the resin-mold interface, increasing the interface layer thickness to 50-100 nm, laying the foundation for subsequent demolding.

[0047] The temperature is then increased to 115-121°C at a rate of 3-5°C / min for final curing, and maintained at this temperature for 15-20 minutes. Under high temperature conditions, the resin completes full cross-linking and forms a stable mechanical structure. The migration of stearamide reaches equilibrium, forming a continuous low surface energy film, which significantly reduces the interfacial adhesion between the resin lens and the mold.

[0048] After final curing, the mold is cooled to 5-10°C below the glass transition temperature (Tg) of the resin at a rate of 4-6°C / min. During the cooling process, a slight positive pressure of 0.01-0.02MPa is maintained in the cavity to prevent air from seeping into the gap between the resin lens and the mold. At this time, as the temperature drops below Tg, the molecular chain rigidity of the resin increases and the resin shrinks as a whole, forming an initial gap of 0.1-0.2mm with the mold cavity.

[0049] Subsequently, the mold is controlled to open slightly to a gap of 0.3-0.5 mm at a rate of 0.05-0.1 mm / s. Dry nitrogen gas matching the current temperature is introduced into the gap. The nitrogen gas quickly fills the gap to form an air cushion, which not only prevents the resin lens from adhering to the mold again, but also removes the residual trace oligomers, thus achieving a pre-separation effect.

[0050] In a preferred embodiment of the present invention, in step S3, the temperature is further reduced from 5~10°C below the glass transition temperature of the resin to 59~61°C at a rate of 4~6°C / min. During the cooling process, the mold cavity is maintained at a slight positive pressure of 0.01~0.02MPa. Cooling to 59~61°C at a moderate rate of 4~6°C / min ensures that the lens temperature is much lower than the glass transition temperature, promoting complete styling of the resin molecular chains and stabilizing the shrinkage amount. This avoids internal stress caused by excessively rapid cooling or production efficiency being affected by excessively slow cooling. At the same time, maintaining a slight positive pressure of 0.01~0.02MPa in the mold cavity ensures that the relative position of the lens and the mold is stable during the shrinkage process, preventing dimensional deviations caused by pressure fluctuations. Furthermore, the stable pressure environment, combined with the gap formed during shrinkage, provides a uniform force foundation for subsequent compressed air pulse demolding, further protecting the lens.

[0051] As a preferred embodiment of the present invention, in step S3, the compressed air pulse source is dry compressed air with a dew point ≤ -40℃, the pulse pressure is released in a stepped manner, the buffer stage pressure is 0.05±0.005MPa, the peak stage pressure is 0.08±0.01MPa, the total pulse time is 0.4~0.6s, the diameter of the air inlet on the parting surface is 0.5~1mm, the number is 3~4 and they are evenly distributed along the circumference;

[0052] More specifically, dry compressed air pulses with a dew point ≤ -40℃ are injected through 3-4 evenly distributed circumferential air inlets with a diameter of 0.5-1mm on the parting surface of the mold, using a stepped release mode:

[0053] Initial buffering stage: pressure 0.05±0.005MPa, lasting 0.1~0.125s, airflow slowly fills the gap, further loosening the interface adsorption between the resin lens and the mold;

[0054] Peak stage: pressure 0.08±0.01MPa, lasting 0.2~0.35s, the airflow overcomes the residual adhesion with greater pressure, pushing the resin lens to completely separate from the mold;

[0055] Final buffering phase: pressure 0.05±0.005MPa, lasting 0.1~0.125s, the airflow smoothly lifts the lens to avoid edge damage caused by its falling due to gravity;

[0056] The total pulse time is controlled at 0.4~0.6s, so that the lens and mold can be separated in a very short time, reducing external interference.

[0057] During this process, the interfacial friction coefficient of stearamide is reduced to below 0.02. Its low surface energy characteristics work synergistically with the uniform driving force of the stepped air pressure to make the demolding force distribution deviation ≤5%, ultimately achieving automatic lens detachment with no scratches on the surface and no edge cracks.

[0058] The beneficial effects of this invention are as follows:

[0059] In this invention, stearamide is uniformly incorporated into the resin base material under ultrasonic dispersion. During the curing process, it migrates directionally to the interface between the resin lens and the mold to form a low surface energy film. Combined with mold micro-opening and nitrogen assistance, it effectively avoids problems such as scratches on the lens surface and edge cracking caused by uneven demolding force in traditional processes. At the same time, the curing agent is dispersed into ≤10μm microdroplets by high-frequency ultrasound and screw pushing, which significantly improves the mixing uniformity, avoids refractive index fluctuations caused by local reaction differences, increases the lens transmittance by 1~2%, reduces haze to below 0.3%, and effectively ensures optical uniformity.

[0060] This invention employs a stepped curing process consisting of preliminary curing, temperature maintenance, micro-ventilation, and final curing. After preliminary curing, the mold is slightly opened and dry nitrogen is introduced. On one hand, the nitrogen quickly fills the gaps, preventing the resin lens from adhering to the mold cavity and achieving a pre-demolding effect. On the other hand, the nitrogen can remove trace amounts of residual oligomers on the cavity surface, preventing them from forming adhesion points after curing. Combined with the silanization treatment of the mold cavity, this further reduces the interfacial adhesion between the resin lens and the mold, fundamentally solving problems such as lens edge tearing and surface scratches caused by one-time strong demolding in traditional processes, and effectively improving the integrity of demolding. Attached Figure Description

[0061] Figure 1 This is a diagram of the lens structure formed using the optical lens processing technology of the present invention;

[0062] Reference numerals: 1. Lens body; 2. Interface layer. Detailed Implementation

[0063] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0064] 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 in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0065] The sources of raw materials and equipment used in the embodiments and comparative examples are shown in Table 1:

[0066] Table 1 Sources of Raw Materials and Equipment

[0067]

[0068] The buffer tank is bottom-feeded, and a vacuum vent is provided at the top of the tank to maintain a slight negative pressure of -0.005 to -0.01 MPa. A diffusion cone is installed at the bottom inlet. The diffusion cone diffuses in an inverted cone shape from bottom to top, and then the inner diameter remains unchanged. Finally, it flows out from the side of the buffer tank. The cone angle of the diffusion cone is 60°. The residence time of the mixture in the buffer tank is about 0.5 to 1 minute.

[0069] The mold parting surface has three air inlets with a diameter of 0.8mm evenly distributed;

[0070] The mold cavity is silanized, with a surface roughness Ra=0.01μm and a surface tension of 18mN / m.

[0071] Example 1: In this example, optical lenses are processed using CR-39 resin as the resin base material. The specific steps are as follows:

[0072] S1. Raw material mixing and processing

[0073] S11. Inject CR-39 resin base material into the mixing tank, turn on the ultrasonic vibrator at the bottom of the tank, and continuously process it for 4 minutes with an ultrasonic frequency of 22kHz and a power of 250W. At the same time, keep the mixing tank in a 45℃ water bath to relax the molecular chains of the resin base material and make it present a microfluidic state.

[0074] S12. Under continuous ultrasonic conditions, stearamide at a mass ratio of 0.3 wt% is added to the resin matrix at a uniform rate, and the stearamide and resin matrix are dispersed in a stable system by using ultrasonic shear force.

[0075] S13. Benzoyl peroxide with a viscosity of 15 mPa·s is injected into the system as a curing agent using a precision screw pump, with the flow rate controlled to be ±0.1 mL / min, and the weight ratio of resin base to curing agent is 100:3; at this time, the ultrasonic parameters are adjusted to 28 kHz and 300 W, the screw pump outlet is located 6 mm below the liquid surface, the discharge direction is consistent with the direction of the ultrasonic vibration wave peak, and the pushing rate is 5 mL / min;

[0076] S14. The mixture enters the buffer tank, and the vacuum vent at the top of the tank maintains a slight negative pressure of -0.008MPa. The mixture stays in the tank for 0.8 minutes to eliminate pulse fluctuations and defoaming, and then is output to the mold at a uniform speed.

[0077] S2. Stepped curing

[0078] S21. Preliminary curing: Inject the mixture into the mold cavity and heat it from room temperature to 78°C at a rate of 6°C / min, maintaining the temperature until the lens reaches a Shore D hardness of 35, with a curing time of approximately 480s.

[0079] S22. Cooling and relaxation: Cool down by 18°C ​​at a rate of 3°C / min and maintain for 3min to promote the migration of stearamide to the resin-mold interface and form a low surface energy interface layer 2 on the lens body 1.

[0080] S23. Final curing: Heat to 118°C at a rate of 4°C / min and maintain for 18 min to allow the resin to fully crosslink; then cool to 90°C at a rate of 5°C / min. 90°C is 8°C below the glass transition temperature of CR-39. During the cooling process, maintain a slight positive pressure of 0.015MPa in the cavity to prevent air from penetrating.

[0081] S24. Pre-separation: Control the mold to open slightly to a gap of 0.4 mm at a rate of 0.08 mm / s, and introduce dry nitrogen at 90°C at a flow rate of 4 L / min for 11 seconds to form an air cushion and carry away the oligomers, thus achieving pre-separation.

[0082] S3. Precise demolding

[0083] S31. Gradient cooling: Cool from 90℃ to 60℃ at a rate of 5℃ / min, maintaining a slight positive pressure of 0.015MPa in the cavity to fix the molecular chain of the lens and stabilize the gap with the mold at 0.4mm.

[0084] S32. Air pressure separation: A pulse of dry compressed air with a dew point of -45℃ is injected into the air inlet of the mold parting surface, and a stepped pressure release is adopted; that is, 0.05MPa release for 0.11s, 0.08MPa release for 0.3s, 0.05MPa release for 0.11s, and the total pulse time is 0.52s. Under the synergistic effect of air pressure and stearamide interface layer, the resin lens separates from the mold without damage and falls off automatically.

[0085] Example 2:

[0086] In this embodiment, optical lenses are fabricated using MR-10 resin as the resin base material. The specific steps are as follows:

[0087] S1. Raw material mixing and processing

[0088] S11. Inject MR-10 resin base material into the mixing tank, turn on the ultrasonic vibrator at the bottom of the tank, and continuously process it for 3.5 minutes with an ultrasonic frequency of 24kHz and a power of 200W. At the same time, keep the mixing tank in a 48℃ water bath to relax the molecular chains of the resin base material and make it present a microfluidic state.

[0089] S12. Under continuous ultrasonic conditions, stearamide at a mass ratio of 0.25 wt% is added to the resin matrix at a uniform rate, and the ultrasonic shear force is used to form a stable dispersion system between the stearamide and the resin matrix.

[0090] S13. Inject tert-butyl hydrogen peroxide with a viscosity of 25 mPa·s into the system as a curing agent using a precision screw pump, controlling the flow rate accuracy to ±0.1 mL / min, and ensuring the weight ratio of resin base to curing agent is 100:2.5; at this time, the ultrasonic parameters are adjusted to 26 kHz and 300 W, the screw pump outlet is located 6 mm below the liquid surface, the discharge direction is consistent with the direction of the ultrasonic vibration wave peak, and the pushing rate is 7 mL / min;

[0091] S14. The mixture enters the buffer tank, and the vacuum vent at the top of the tank maintains a slight negative pressure of -0.008MPa. The mixture stays in the tank for 0.6 minutes to eliminate pulse fluctuations and defoaming, and then is output to the mold at a uniform speed.

[0092] S2. Stepped curing

[0093] S21. Preliminary curing: The mixture is injected into the mold cavity and heated from room temperature to 75°C at a rate of 7°C / min, and maintained until the lens reaches Shore D hardness of 34. The curing time is about 460s.

[0094] S22. Cooling and relaxation: Cool down by 16°C at a rate of 2°C / min and maintain for 2.5min to promote the migration of stearamide to the interface between the resin lens and the mold, forming a low surface energy interface layer 2 on the lens body 1.

[0095] S23. Final curing: Heat to 116°C at a rate of 3°C / min and maintain for 16 min to allow the resin to fully crosslink; then cool to 105°C at a rate of 4°C / min. 105°C is 6°C below the glass transition temperature of MR-10. During the cooling process, maintain a slight positive pressure of 0.015MPa in the cavity to prevent air from penetrating.

[0096] S24. Pre-separation: Control the mold to open slightly to a gap of 0.35mm at a rate of 0.06mm / s, and introduce dry nitrogen gas at 105℃ at a flow rate of 3.5L / min for 10s to form an air cushion and carry away the oligomers, thus achieving pre-separation.

[0097] S3. Precise demolding

[0098] S31. Gradient cooling: Cool from 105℃ to 61℃ at a rate of 4℃ / min, maintaining a slight positive pressure of 0.012MPa in the cavity to fix the molecular chain of the lens and stabilize the gap with the mold at 0.35mm;

[0099] S32. Air pressure separation: A pulse of dry compressed air with a dew point of -45℃ is injected into the air inlet of the mold parting surface, and a stepped pressure release is adopted; that is, 0.05MPa release for 0.1s, 0.075MPa release for 0.25s, 0.05MPa release for 0.11s, and the total pulse time is 0.45s. Under the synergistic effect of air pressure and stearamide interface layer, the resin lens separates from the mold without damage and falls off automatically.

[0100] Example 3:

[0101] This embodiment uses MR-8 resin as the base material to process optical lenses. The specific steps are as follows:

[0102] S1. Raw material mixing and processing

[0103] S11. Inject MR-8 resin base material into the mixing tank, turn on the ultrasonic vibrator at the bottom of the tank, and continuously process it for 5 minutes with an ultrasonic frequency of 20kHz and a power of 300W. At the same time, keep the mixing tank in a 42℃ water bath to relax the molecular chains of the resin base material and make it present a microfluidic state.

[0104] S12. Under continuous ultrasonic conditions, stearamide at a mass ratio of 0.4 wt% is added to the resin matrix at a uniform rate, and the stearamide and resin matrix are dispersed by ultrasonic shearing force.

[0105] S13. Benzoyl peroxide with a viscosity of 20 mPa·s is injected into the system as a curing agent using a precision screw pump, with the flow rate controlled to be ±0.1 mL / min, and the weight ratio of resin base to curing agent is 100:4; at this time, the ultrasonic parameters are adjusted to 30 kHz and 400 W, the screw pump outlet is located 6 mm below the liquid surface, the discharge direction is consistent with the direction of the ultrasonic vibration wave peak, and the pushing rate is 10 mL / min;

[0106] S14. The mixture enters the buffer tank, and the vacuum vent at the top of the tank maintains a slight negative pressure of -0.008MPa. The mixture stays in the tank for 1 minute to eliminate pulse fluctuations and defoam, and then is output to the mold at a uniform speed.

[0107] S2. Stepped curing

[0108] S21. Preliminary curing: Inject the mixture into the mold cavity and raise the temperature from room temperature to 81°C at a rate of 8°C / min, maintaining the temperature until the lens reaches a Shore D hardness of 37. The curing time is approximately 500 seconds.

[0109] S22. Cooling and relaxation: Cool down by 20°C at a rate of 5°C / min and maintain for 4min to promote the migration of stearamide to the interface between the resin lens and the mold, forming a low surface energy interface layer 2 on the lens body 1.

[0110] S23. Final curing: Heat to 120°C at a rate of 5°C / min and maintain for 20 min to allow the resin to fully crosslink; then cool to 100°C at a rate of 6°C / min. 100°C is 10°C below the glass transition temperature of MR-8. During the cooling process, maintain a slight positive pressure of 0.02MPa in the cavity to prevent air from penetrating.

[0111] S24. Pre-separation: Control the mold to open slightly to a gap of 0.5 mm at a rate of 0.1 mm / s, and introduce dry nitrogen gas at 100°C at a flow rate of 5 L / min for 12 seconds to form an air cushion and carry away the oligomers, thus achieving pre-separation.

[0112] S3. Precise demolding

[0113] S31. Gradient cooling: Cool from 100℃ to 59℃ at a rate of 6℃ / min, maintaining a slight positive pressure of 0.02MPa in the cavity to fix the molecular chains of the lens and stabilize the gap with the mold at 0.5mm;

[0114] S32. Air pressure separation: A pulse of dry compressed air with a dew point of -45℃ is injected into the air inlet of the mold parting surface, and a stepped pressure release is adopted; that is, 0.055MPa release for 0.1s, 0.09MPa release for 0.35s, 0.05MPa release for 0.11s, and the total pulse time is 0.56s. Under the synergistic effect of air pressure and stearamide interface layer, the resin lens separates from the mold without damage and falls off automatically.

[0115] Comparative Example 1:

[0116] Unlike Example 1, this comparative example uses conventional technology, and the steps are as follows: conventional mechanical stirring is used for mixing, the resin base is not ultrasonically treated, and no stearamide is added; the curing agent is injected through a regular pump and dispersed by mechanical stirring only; the curing process is a single temperature of 100°C for 2 hours; and the demolding is done by mechanical ejection.

[0117] Comparative Example 2:

[0118] Unlike Example 1, stearamide was not added in step S1 of this comparative example, while the remaining steps were the same as in Example 1.

[0119] Comparative Example 3:

[0120] Unlike Example 1, in step S1 of this comparative example, the resin base material is only mechanically stirred and not ultrasonically treated. The remaining steps are the same as in Example 1.

[0121] Comparative Example 4:

[0122] Unlike Example 1, this comparative example directly cools to 60°C after final curing, skips the step of micro-mold opening and nitrogen gas purging, and directly proceeds to step S31 gradient cooling. The remaining steps are the same as in Example 1.

[0123] Comparative Example 5:

[0124] Unlike Example 1, this comparative example does not perform a cooling relaxation step after initial curing in S21, but directly proceeds to final curing in S23. The remaining steps are the same as in Example 1.

[0125] The lenses prepared in the examples and comparative examples were tested as follows. Three samples were tested for each case, and the average value was taken to obtain the results in Table 2.

[0126] The test methods for transmittance and haze are as follows: According to GB / T2410-2008 "Determination of transmittance and haze of transparent plastics", a haze meter of model NDH-5000 is used for testing. The sample must be cleaned with anhydrous ethanol. Under the environment of 23℃±2℃ and relative humidity of 50%±5%, visible light of 380~780nm is used as the light source. Three points are measured, namely the center of the lens and 1 / 3 of the distance from the edge. The average value is taken as the transmittance.

[0127] Haze is the ratio of the sample’s scattered light flux to the total transmitted light flux, and the average value is taken from 3 test points.

[0128] The refractive index deviation is tested as follows: According to GB / T7962.1-2010 "Test Methods for Colorless Optical Glass - Part 1: Refractive Index and Dispersion Coefficient", an Abbe refractometer is used with a sodium lamp as the light source. Under an environment of 20℃±0.5℃, the refractive index is measured at one point at the center and one point at each of the four sides of the lens. The difference between the maximum and minimum values ​​is calculated as the refractive index deviation. The four points at each of the four sides are symmetrical points 5mm away from the edge of the lens.

[0129] Visual inspection:

[0130] Visual inspection: Under a 40W fluorescent lamp, at a distance of 30-50cm from the sample, observe surface scratches, edge cracks, and stains, etc.

[0131] Microscopic inspection: Observe minute defects using a 10-50x microscope and record the presence and size of defects.

[0132] Table 2 shows the test results of the lenses prepared in the examples and comparative examples.

[0133]

[0134] Comparative Example 1 uses a traditional process without ultrasonic treatment, resulting in poor fluidity of the resin base. The curing agent is dispersed only by mechanical stirring, leading to uneven local curing, low light transmittance, high haze, and large refractive index deviation. In addition, the absence of stearamide and mechanical ejection and demolding result in serious appearance defects such as surface scratches and edge cracking, and overall deterioration of all properties.

[0135] In Comparative Example 2, due to the lack of a low surface energy interface layer formed by stearamide, the adhesion between the resin lens and the mold was large, resulting in edge cracking and a significant increase in surface tear rate during demolding. At the same time, the lack of stearamide affected the dispersion stability of the system, with haze slightly higher than in the Example and a significant decrease in appearance performance.

[0136] Comparative Example 3 did not use ultrasonic treatment; mechanical stirring alone could not disperse the curing agent into microdroplets, resulting in large differences in local curing reactions. This led to reduced light transmittance, increased haze, and increased refractive index deviation. Mechanical stirring introduced more air bubbles, which increased scattered light and further enhanced haze, affecting optical performance. Although the demolding process was complete, the optical performance was still significantly inferior to that of the Example.

[0137] Comparative Example 4 lacked the pre-separation step and did not vent nitrogen gas through the mold after final curing. As a result, the resin lens adhered locally to the mold, forming adhesion points. During demolding, the surface was scratched and the edges were torn, leading to an increase in the appearance defect rate. Although the optical performance was less affected, the physical damage caused by adhesion significantly reduced the product qualification rate.

[0138] Comparative Example 5 did not cool down after initial curing, the internal stress of the resin was not released, and the stearamide migration was insufficient, resulting in an increased refractive index deviation and a slight decrease in light transmittance; during demolding, the interfacial adhesion increased, and the number of edge microcracks and surface scratches increased, and the overall performance was inferior to that of the Example.

[0139] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An optical lens processing technology, characterized in that, include: S1. The resin base material is ultrasonically treated to a microfluidic state at a frequency of 20-25 kHz and a power of 150-300 W for 3-5 min. Then, under continuous ultrasonic treatment, 0.2-0.4 wt% stearamide is added at a uniform rate and dispersed evenly. The curing agent is injected into the resin base material through a screw pump. The ultrasonic frequency is adjusted to 25-30 kHz and the power is increased to 300-400 W. The mixture is pushed by the screw for 2-3 min. The curing agent is dispersed into microdroplets ≤10 μm and uniformly mixed with the resin base material by the synergistic effect of ultrasonic vibration and screw pushing. The mixture is then discharged through a buffer tank. S2. Inject the mixture into the mold and heat it to 65~81℃ for initial curing. When the lens reaches the preset hardness or preset curing time, cool it down by 15~20℃ and maintain it for 2~4 minutes. Then heat it up to 115~121℃ for final curing. After final curing, cool it down to 5~10℃ below the glass transition temperature of the resin, control the mold to open slightly to form a gap and introduce nitrogen gas. S3. After the mold cools to 59~61℃, inject compressed air pulses into the mold parting surface to separate the resin lens from the mold and allow it to fall off automatically.

2. The optical lens processing technology according to claim 1, characterized in that, The resin base is any one of MR-8 resin, MR-10 resin or CR-39 resin, and the curing agent is at least one of benzoyl peroxide and tert-butyl hydroperoxide.

3. The optical lens processing technology according to claim 1, characterized in that, In step S1, the discharge port of the screw pump is located 5-10 mm below the surface of the resin base liquid, and the discharge direction is consistent with the direction of the ultrasonic vibration peak. When the viscosity of the curing agent is 10~20 mPa·s, and the ultrasonic power is 300W, the corresponding pushing rate is 4~6 mL / min; When the viscosity of the curing agent is 20~30 mPa·s, and the ultrasonic power is 300W, the corresponding pushing rate is 6~8 mL / min; During the process, for every 50W increase in ultrasonic power, the pushing rate increases by 1~2mL / min.

4. The optical lens processing technology according to claim 1, characterized in that, In step S1, the buffer tank is a vertical cylindrical structure with a vacuum extraction port at the top to maintain a slight negative pressure of -0.005 to -0.01 MPa; the residence time of the mixture in the buffer tank is 0.5 to 1 minute, and a diffusion cone with a cone angle of 60° to 90° is provided at the inlet.

5. The optical lens processing technology according to claim 1, characterized in that, In step S2, the preset hardness is Shore D hardness 35±2, and the preset curing time is 450~500s.

6. The optical lens processing technology according to claim 5, characterized in that, In step S2, the surface roughness Ra of the mold cavity is ≤0.02μm, and the inner wall of the cavity is silanized, with a surface tension ≤20mN / m; after final curing, the gap of the micro-opening mold is 0.3~0.5mm, the opening and closing speed is controlled at 0.05~0.1mm / s, the temperature of the nitrogen gas introduced is the same as the current temperature of the mold, the flow rate is 3~5L / min, the introduction time is 10~12s, and the moisture content in the nitrogen gas is ≤0.01%.

7. The optical lens processing technology according to claim 5, characterized in that, In step S2, the heating rate of the mold from room temperature to 65~81℃ is 5~8℃ / min, the cooling rate after initial curing is 1~5℃ / min, the heating rate to 115~121℃ is 3~5℃ / min, and it is maintained at 115~121℃ for 15~20min. After final curing, the mold is cooled to 5~10℃ below the glass transition temperature of the resin at a rate of 4~6℃ / min. During the cooling process, the mold cavity is maintained at a slight positive pressure of 0.01~0.02MPa.

8. The optical lens processing technology according to claim 7, characterized in that, In step S3, the temperature is further reduced from 5~10℃ below the glass transition temperature of the resin to 59~61℃ at a rate of 4~6℃ / min. During the cooling process, the mold cavity is maintained at a slight positive pressure of 0.01~0.02MPa.

9. The optical lens processing technology according to claim 8, characterized in that, In step S3, the compressed air pulse source is dry compressed air with a dew point ≤ -40℃. The pulse pressure is released in a stepped manner, with a buffer stage pressure of 0.05±0.005MPa and a peak stage pressure of 0.08±0.01MPa. The total pulse time is 0.4~0.6s. The diameter of the air inlet on the parting surface is 0.5~1mm, and there are 3~4 inlets that are evenly distributed along the circumference.

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