Optical lens processing technology

Abstract

The invention relates to the technical field of lens processing, in particular to an optical lens processing technology which comprises the following steps: S1, carrying out ultrasonic treatment on a resin base material, adding stearamide, injecting a curing agent into the resin base material, and uniformly mixing the curing agent with the resin base material by utilizing ultrasonic vibration and screw pushing; s2, the mixture is injected into a mold and heated to 65-81 DEG C for preliminary curing, and when the lens reaches the preset hardness or the preset curing time, the temperature is reduced by 15-20 DEG C and maintained; the temperature is increased to 115-121 DEG C for final curing, after final curing is completed, the temperature is reduced to 5-10 DEG C below the resin glass transition temperature, the mold is controlled to be slightly opened to form a gap, and nitrogen is introduced; s3, after the mold is cooled to 59-61 DEG C, compressed air pulses are injected into the parting surface of the mold; the problems of poor lens optical performance, low dimensional precision and high rejection rate caused by non-uniform dispersion of a curing agent, concentrated curing stress and demolding damage in an existing optical lens processing technology are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lens processing, in particular to an optical lens processing technology. BACKGROUND

[0002] Optical resin lenses are widely used in the fields of glasses, optical instruments and the like due to their advantages of light weight, good impact resistance and low processing cost. The core of the processing technology is the uniform mixing of resin base material and curing agent, controllable curing and non-destructive demolding, which directly affects the optical performance and mechanical performance of the lens. The optical performance mainly reflects in the uniformity of light transmittance and refractive index, and the mechanical performance mainly reflects in the hardness and anti-yellowing ability.

[0003] In the prior art, the mixing of resin base material and curing agent mainly depends on mechanical stirring. However, the curing agent has large particle size, which easily leads to uneven local curing reaction and affects the stability of the refractive index of the lens. In addition, mechanical stirring easily introduces air bubbles, which requires an additional defoaming process to prolong the processing cycle. Some processes attempt to introduce ultrasonic assisted mixing, but the dispersion efficiency is limited. The demolding process also often faces many problems. Traditional processes mainly rely on mechanical ejection, manual stripping or single internal release agent assistance. However, mechanical ejection easily causes scratches on the surface of the lens and edge cracking, especially for complex curved or thin lenses, the damage risk is higher. Manual stripping not only has low efficiency, but also is difficult to ensure uniform stress, which easily causes lens deformation. Although the use of single internal release agent can reduce the difficulty of demolding to some extent, when the resin lens and the mold cavity are tightly bonded and the shrinkage rate after curing is small, it is still difficult to achieve smooth demolding, and external force needs to be applied, which also affects the quality of the lens. Some processes attempt to introduce some auxiliary means during the curing process, but the existing curing process design mainly focuses on how to improve the curing speed and the hardness of the lens, and the correlation between the curing stage and the demolding effect is still insufficient. Therefore, there is an urgent need for an optical lens processing technology that can achieve ultra-fine dispersion of curing agent, precise control of curing stress and automatic non-destructive demolding to improve product quality and production efficiency. The information disclosed in this BACKGROUND section is only for the purpose of enhancing the understanding of the general background of the application and should not be taken as admitting that such information is prior art with respect to any country. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an optical lens processing technology to overcome the problems of poor optical performance, low dimensional accuracy and high scrap rate of lenses caused by uneven dispersion of curing agent, stress concentration and demolding damage in the existing optical lens processing technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the present application is: An optical lens processing technology, comprising: S1. ultrasonic treatment of the resin base to micro-flow state, add 0.2~0.4wt% of stearic acid amide and disperse uniformly, inject curing agent into the resin base through the screw pump, use the synergistic effect of ultrasonic vibration and screw pushing to disperse the curing agent into micro-droplets ≤10μm and mix uniformly with the resin base, the mixed material is guided out through the buffer tank; In this step, under ultrasonic environment, 0.2~0.4% of stearic acid amide by weight of the resin base is added uniformly to the resin base. The stearic acid amide acts as an internal release agent. The hydrophobic long chain in its molecular structure can quickly disperse under the action of shear force generated by ultrasonic vibration, forming 1~3μm micro-particles and uniformly embedding in the resin base. At the same time, ultrasonic vibration promotes the weak interaction between the stearic acid amide molecules and the polar groups of the resin base, ensuring dispersion stability and laying the foundation for the subsequent directional migration of the stearic acid amide to the resin lens and mold interface, thereby pre-building an interface layer with low surface energy without affecting the optical performance of the resin. The addition amount of stearic acid amide is 0.2~0.4wt% of the resin base, which provides sufficient amount of material basis for the directional migration of the curing stage to the resin lens and mold interface, avoiding uneven dispersion of stearic acid amide in the resin or affecting the optical and mechanical properties of the resin due to excessive addition amount. After the stearic acid amide is uniformly mixed, the curing agent is injected into the resin base through the precision screw pump. The precision screw pump transports the curing agent from the storage tank to the inside of the stirring tank, controls the flow accuracy of the curing agent to be ±0.1mL / min, and makes the ratio of the base material to the curing agent strictly meet the process requirements. When the curing agent just enters the resin base, it will be immediately subjected to high-frequency oscillation by the ultrasonic vibrator at the bottom of the stirring tank. The cavitation effect generated by the ultrasonic wave will tear the curing agent liquid into micro-droplets ≤10μm, and the linear power of the screw pump will quickly bring the above micro-droplets into the deep part of the resin base, avoiding aggregation near the inlet. At this time, the screw pushing of the screw pump and the high-frequency oscillation of the ultrasonic wave form a coupling. Compared with the 20~50μm curing agent droplets in the prior art, the uniformity of the curing reaction is significantly improved, and uniform mixing is achieved. The addition amount of the curing agent is 2~4% of the weight of the resin base. The above amount of curing agent provides sufficient active centers for the free radical polymerization of the resin base, ensures the formation of a stable and uniform cross-linked network, meets the requirements of lens for hardness and anti-yellowing mechanical properties, and also avoids excessive local curing reaction due to excessive addition amount, which may cause stress concentration or lens embrittlement. S2. Inject the mixed material into the mold and heat to 65~81℃ for preliminary curing. When the lens reaches the preset hardness or the preset curing time, reduce the temperature by 15~20℃ and maintain for 2~4min. Then heat to 115~121℃ for final curing. After final curing, reduce the temperature to 5~10℃ below the glass transition temperature of the resin, control the mold to slightly open to form a gap and introduce nitrogen. The step adopts a step-by-step curing process to realize precise control of complete crosslinking of the resin and interfacial adhesion through step-by-step regulation of preliminary curing, temperature reduction relaxation, final curing and temperature reduction pre-separation; first, through preliminary temperature increase curing and temperature reduction relaxation, the resin forms a stable crosslinked network to ensure mechanical properties, and at the same time promotes the migration of stearic amide to the interface to form a low surface energy layer; after final curing, the temperature is reduced to the glass transition temperature, and the mold is slightly opened and nitrogen is injected, using the shrinkage of the resin and the nitrogen gas cushion to realize pre-separation, reducing the bonding force between the resin lens and the mold, and solving the problem of insufficient correlation between curing and demolding; S3. After the mold is cooled to 59~61℃, compressed air pulses are injected into the mold parting surface to separate the resin lens from the mold and automatically fall off.

[0006] The step realizes non-destructive separation of the resin lens and the mold through the synergistic effect of gradient temperature reduction and step-by-step air pressure separation; the mold is cooled to 59~61℃ to shape the lens and stabilize the gap, and by injecting step-by-step compressed air pulses into the parting surface, the low surface energy interface layer is uniformly overcome to separate the resin lens from the mold, avoiding scratches or cracks caused by mechanical ejection or manual peeling, and realizing efficient and non-destructive demolding.

[0007] As a preferred scheme of the present application, the resin base material 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; The above resin base material has good light transmittance, mechanical strength and molding performance, and can provide a basic guarantee for the optical and mechanical properties of the lens as a high-quality substrate; The above curing agent not only has the activity of initiating free radical polymerization of the resin base material, but also can promote the resin to form a stable crosslinked network to ensure the hardness and other mechanical properties of the lens; The viscosity of benzoyl peroxide is 10~20mPa·s, and the viscosity of tert-butyl hydroperoxide is 20~30mPa·s; The above viscosity range is adapted to the synergistic effect of ultrasonic vibration and screw pushing in step S1, and can be effectively dispersed into droplets ≤10μm under the tearing effect of ultrasonic cavitation and the diffusion effect of screw pushing, ensuring uniform mixing of the curing agent and the resin base material, and avoiding the problem of uneven local curing reaction caused by too large particle size.

[0008] As a preferred scheme of the present application, 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; The resin base is subjected to ultrasonic treatment alone, specifically, the resin base is injected into the stirring tank, and the ultrasonic vibrator at the bottom of the tank is turned on, the resin base is subjected to continuous treatment by using an ultrasonic frequency of 20-25 kHz and a power of 150-300 W, so that the molecular chain of the resin base is relaxed under the action of vibration, and a micro-flow state is presented, and the fluidity is improved, in order to further reduce the viscosity of the resin base to enhance the ultrasonic dispersion effect, the stirring tank can be subjected to water bath heat preservation, and the temperature is controlled at 40-50 DEG C, and the temperature is adjusted according to the type of the resin, for example, the CR-39 resin is preferably 45 DEG C; Then, stearic amide is added at a constant speed under the condition of continuous ultrasonic, after the curing agent is injected, the ultrasonic frequency is adjusted to 25-30 kHz, and the power is increased to 300-400 W, and the screw pushing is cooperated for 2-3 min; The continuous ultrasonic can make the stearic amide quickly dispersed into 1-3 mu m small particles through shear force, and at the same time, the stearic amide is promoted to form a weak interaction with the polar group of the resin base, so as to ensure the dispersion stability and lay a foundation for the subsequent directional migration to the interface between the resin lens and the mold; and after the curing agent is injected, the ultrasonic parameters are strengthened, the cavitation effect and shear force of the ultrasonic are enhanced, the power of the screw pushing is matched, the curing agent is effectively torn into micro-droplets with a particle size of less than or equal to 10 mu m and is uniformly mixed, and local aggregation is avoided, so that the problem of local curing unevenness caused by large particle size of the curing agent in the prior art is solved.

[0009] As a preferred scheme of the present application, in step S1, the discharge port of the screw pump is located 5-10 mm below the liquid level of the resin base, and the discharge direction is consistent with the peak direction of ultrasonic vibration; This position can make the curing agent directly in the action area of ultrasonic vibration as soon as it is injected, avoiding the introduction of air bubbles when the curing agent is exposed above the liquid level; the discharge direction consistent with the peak direction can make the curing agent liquid flow accurately superimposed with the energy concentration area of ultrasonic vibration, maximize the tearing effect of ultrasonic cavitation effect, and make the curing agent be preliminarily dispersed as soon as it enters the base, laying a foundation for subsequent uniform mixing with the screw pushing.

[0010] When the viscosity of the curing agent is 10-20 mPa·s, the corresponding pushing rate is 4-6 mL / min when the ultrasonic power is 300 W; When the viscosity of the curing agent is 20-30 mPa·s, the corresponding pushing rate is 6-8 mL / min when the ultrasonic power is 300 W; The pushing rate is increased by 1-2 mL / min synchronously with the increase of 50 W of the ultrasonic power.

[0011] For low viscosity curing agent, lower pushing rate can avoid insufficient dispersion caused by too fast liquid flow, and effective tearing can be realized with 300W ultrasonic power; for high viscosity curing agent, higher pushing rate can overcome viscous resistance to ensure that it is fully brought into the base material deep under the same ultrasonic power, and the synchronous increase of pushing rate when the ultrasonic power is increased can further enhance the coupling effect of energy and power, so that curing agents with different viscosities can be stably dispersed into microdroplets with a size of ≤10μm.

[0012] As a preferred scheme of the present application, in step S1, the buffer tank is a vertical cylindrical structure, a vacuum air outlet is arranged at the top of the tank to maintain a micro-negative pressure of-0.005~-0.01MPa; the residence time of the mixture in the buffer tank is 0.5~1min, and a diffusion cone is arranged at the inlet with a cone angle of 60°~90°; More specifically, the vertical cylindrical flow channel can guide the mixture to form a stable laminar flow state, avoiding turbulent disturbance caused by irregular structure, thereby reducing the risk of coalescence of curing agent microdroplets during flow, and facilitating 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; The micro-negative pressure environment at the top of the tank can promote the floating and escaping of small bubbles in the mixture, and the residence time of the buffer tank can realize efficient defoaming, solving the problem that mechanical stirring easily introduces bubbles and requires an additional defoaming process in the prior art, while avoiding excessive negative pressure that causes the base material to volatilize or change in composition; The above residence time can provide sufficient homogenization time for curing agent microdroplets, ensuring further dispersion and uniformity in laminar flow, and offsetting the risk of local coalescence after ultrasonic stop, while avoiding premature curing reaction of the mixture due to prolonged residence; More specifically, the diffusion cone is inverted conical from bottom to top, then the inner diameter remains unchanged, and the flow direction of the mixture is from bottom to top. By arranging the diffusion cone at the inlet, the mixture flow entering the buffer tank can be buffered and diffused, reducing the flow rate and impact force at the inlet, avoiding local turbulent flow that destroys the laminar flow state, and allowing the mixture to be more uniformly distributed on the cross section of the buffer tank, improving homogenization and defoaming effect.

[0013] As a preferred scheme of the present application, in step S2, the pre-set hardness is Shore D hardness 35±2. Within the above hardness range, the resin has certain structural stability, which can support the subsequent cooling relaxation and final curing steps, and the state of incomplete curing can cause stress relaxation of molecular chains during cooling, reducing internal stress concentration; and under the above hardness, stearic amide molecules can still migrate to the resin and mold interface through thermal motion, creating conditions for building a low surface energy interface layer, avoiding excessive curing that hinders the migration of release agent and affects the subsequent release effect; As a preferred scheme of the present application, in step S2, the preset curing time is 450-500 s, which enables the resin base to fully undergo free radical polymerization in the 65-81℃ preliminary curing stage to reach the crosslinking degree required for the preset hardness, avoiding insufficient crosslinking and poor structural stability caused by too short time, and preventing excessive curing of the resin caused by too long time, which makes it difficult for internal stress to be released during subsequent cooling relaxation, and provides sufficient migration time for the stearamide molecules to preliminarily form an interface layer.

[0014] As a preferred scheme of the present application, in step S2, the surface roughness Ra of the mold cavity is ≤0.02 μm, and the inner wall of the cavity is silanized to have a surface tension ≤20 mN / 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 ≤20 mN / m of the silanized inner wall of the cavity can significantly weaken the intermolecular force 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, lay a foundation for smooth demolding, and avoid demolding damage caused by large interfacial adhesion in traditional processes.

[0015] The gap of the slightly opened mold after final curing is 0.3-0.5 mm, the control opening and closing speed is 0.05-0.1 mm / s, the temperature of the nitrogen gas introduced is the same as the current temperature of the mold, the flow rate is 3-5 L / min, the introduction time is 10-12 s, and the water content in the nitrogen gas is ≤0.01%; More specifically, the gap size can provide sufficient space for the nitrogen gas injection to form a stable air cushion, and can also avoid excessive gap that causes the lens to deform under the action of gravity. The slow opening and closing speed can prevent the instantaneous stress generated by the rapid movement of the mold from being transmitted to the lens, so that the lens remains structurally stable during the preliminary separation stage and reduces the risk of edge cracking. The same temperature nitrogen gas can avoid uneven local shrinkage or condensation of water caused by temperature difference, protecting the optical performance of the lens. The flow rate and introduction time enable the nitrogen gas to quickly fill the gap and fully remove residual oligomers, achieving effective preliminary separation. The low water content can prevent water marks from forming on the lens surface, avoiding affecting the optical indicators such as light transmittance.

[0016] As a preferred scheme of the present application, in step S2, the mold is heated from room temperature to 65-81℃ at a rate of 5-8℃ / min, the preliminary cured lens is cooled at a rate of 1-5℃ / min, then heated to 115-121℃ at a rate of 3-5℃ / min, and maintained at 115-121℃ for 15-20 min. 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, and the mold cavity is kept at a micro-positive pressure of 0.01-0.02 MPa during the cooling process. More specifically, step S2 realizes precise control of resin complete crosslinking and interface adhesion through preliminary curing, temperature relaxation, final curing and temperature pre-separation, and the specific process is as follows: The uniformly mixed mixture in S1 is injected into the mold cavity treated by silanization, and the mold is first raised from room temperature to 65-81℃ at a rate of 5-8℃ / min for preliminary curing. In this stage, the curing agent droplets in the resin matrix initiate free radical polymerization under the action of heat, and the molecular chain grows rapidly to form a preliminary crosslinked network. At the same time, stearic amide molecules slowly migrate to the interface between the resin and the mold due to thermal motion, and begin to build an interface layer with low surface energy; When the preset hardness or curing time is reached, the mold is cooled at a rate of 1-5℃ / min by 15-20℃ and maintained for 3-4min. During the cooling process, the activity of the resin molecular chain is weakened, and the stress relaxation of the preliminary crosslinked network occurs, reducing the internal stress concentration caused by rapid polymerization and avoiding the risk of cracking in subsequent processing. At the same time, because the weak interaction between stearic amide and resin polar groups is weakened at low temperature, stearic amide molecules are more likely to migrate to the interface between the resin and the mold, so temperature reduction promotes the directional migration of stearic amide molecules to the interface between the resin and the mold, and the thickness of the interface layer increases to 50-100nm, laying the foundation for subsequent demolding; Subsequently, the temperature is raised to 115-121℃ at a rate of 3-5℃ / min for final curing, and maintained at this temperature for 15-20min. In a high-temperature environment, the resin completes complete crosslinking and forms a stable mechanical structure. The migration of stearic amide reaches equilibrium, forming a continuous low-surface-energy film that significantly reduces the interfacial adhesion between the resin lens and the mold; After final curing is completed, the mold is first cooled to 5-10℃ below the resin glass transition temperature (Tg) at a rate of 4-6℃ / min. During the cooling process, the cavity is maintained at a micro-positive pressure of 0.01-0.02MPa to prevent air from entering the gap between the resin lens and the mold. At this time, the resin has increased rigidity and overall shrinkage due to the temperature dropping below Tg, forming an initial gap of 0.1-0.2mm with the mold cavity; Subsequently, the mold is controlled to open to a gap of 0.3-0.5mm at a rate of 0.05-0.1mm / s, and dry nitrogen matching the current temperature is introduced into the gap. Nitrogen quickly fills the gap to form an air cushion, which not only blocks the secondary adhesion between the resin lens and the mold, but also carries away the residual trace oligomers, achieving the pre-separation effect.

[0017] As a preferred scheme of the present application, in step S3, the temperature is continuously decreased at a rate of 4-6 DEG C / min from 5-10 DEG C below the resin glass transition temperature to 59-61 DEG C, and the mold cavity is kept at a micro-positive pressure of 0.01-0.02 MPa during the temperature decreasing process; the moderate rate of 4-6 DEG C / min to 59-61 DEG C can make the lens temperature far below the glass transition temperature, promote the complete setting of the resin molecular chain and the stable shrinkage, avoid the internal stress caused by too fast temperature decreasing or the influence on production efficiency caused by too slow temperature decreasing; meanwhile, the micro-positive pressure of 0.01-0.02 MPa of the mold cavity can keep the relative position of the lens and the mold stable during the shrinkage process, prevent the size deviation caused by pressure fluctuation, and provide a uniform stress basis for the subsequent compressed air pulse demolding, further ensuring the lens.

[0018] As a preferred scheme of the present application, in step S3, the air source of the compressed air pulse is dry compressed air with a dew point of ≤-40 DEG C, the pulse pressure is released in a stepwise manner, the pressure in the buffer stage is 0.05±0.005 MPa, the pressure in the peak stage is 0.08±0.01 MPa, the total pulse time is 0.4-0.6 s, the diameter of the air inlet of the parting surface is 0.5-1 mm, the number is 3-4 and is uniformly distributed along the circumference. More specifically, the dry compressed air pulse with a dew point of ≤-40 DEG C is injected through the 3-4 air inlets with a diameter of 0.5-1 mm uniformly distributed along the circumference of the mold parting surface, and a stepwise release mode is adopted. The initial buffer stage: the pressure is 0.05±0.005 MPa, and lasts for 0.1-0.125 s; the airflow slowly fills the gap, further loosens the interface adsorption of the resin lens and the mold; The peak stage: the pressure is 0.08±0.01 MPa, and lasts for 0.2-0.35 s; the airflow overcomes the residual adhesion with a larger pressure, and pushes the resin lens and the mold to completely separate; The end buffer stage: the pressure is 0.05±0.005 MPa, and lasts for 0.1-0.125 s; the airflow smoothly lifts the lens, avoiding the edge damage caused by gravity falling; The total pulse time is controlled to be 0.4-0.6 s, so that the lens and the mold are separated in a very short time, and the external interference is reduced.

[0019] In this process, the stearic amide interface friction coefficient is reduced to below 0.02, the low surface energy characteristic cooperates with the uniform driving force of the step pressure to make the demolding force distribution deviation ≤5%, and finally the lens is automatically demolded without scratches on the surface and without cracking on the edge.

[0020] The present application has the following beneficial effects: In the present application, the stearic amide is uniformly mixed into the resin base under the ultrasonic dispersion, and migrates to the interface between the resin lens and the mold during the curing process to form a low surface energy film, which, in combination with the mold micro-opening and nitrogen assistance, effectively avoids the lens surface scratches and edge cracking caused by uneven demolding force in the traditional process, at the same time, the curing agent is dispersed into microparticles of ≤10 μm by high-frequency ultrasonic and screw pushing, which significantly improves the mixing uniformity, avoids the refractive index fluctuation caused by local reaction difference, and improves the lens transmittance by 1~2%, reduces the haze to below 0.3%, and effectively guarantees the optical uniformity. The present application adopts a stepwise curing process of preliminary curing, temperature maintenance, micro-opening and ventilation and final curing, after preliminary curing, the mold is controlled to be micro-opened and dry nitrogen is introduced, on the one hand, the nitrogen is used to fill the gap quickly and block the continuous adhesion between the resin lens and the mold cavity, to realize the pre-demolding effect, on the other hand, the nitrogen can take away the trace amount of oligomers remaining on the surface of the cavity, to avoid the formation of adhesion points after curing, in combination with the silanization treatment of the mold cavity, the adhesion between the resin lens and the mold is further reduced, the problems of lens edge tearing and surface scratching caused by one-time strong demolding in the traditional process are solved from the root, and the demolding integrity is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The lens structure formed by the optical lens processing technology of the present application is shown in the figure; The figure shows that: 1, lens body; 2, interface layer. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application, obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments.

[0023] 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 application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this description, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] The raw materials and equipment used in the examples and comparative examples are shown in Table 1: Table 1 Raw materials and equipment sources

[0025] The buffer tank is a bottom feeding tank, a vacuum air outlet is arranged on the top of the tank to maintain a micro negative pressure of-0.005 to-0.01 MPa, a diffusion cone is arranged at the bottom feeding port, the diffusion cone is inverted conical from bottom to top, then the inner diameter is constant, and finally the mixture flows out from the side of the buffer tank, the cone angle of the diffusion cone is 60°, and the residence time of the mixture in the buffer tank is about 0.5 to 1 min. The mold parting surface is uniformly provided with three air inlets with a diameter of 0.8 mm; The mold cavity is silanized, the surface roughness Ra is 0.01 μm, and the surface tension is 18 mN / m.

[0026] Embodiment 1: In this embodiment, CR-39 resin is used as a resin base material to process an optical lens, and the specific steps are as follows: S1. Raw material mixing treatment S11. The CR-39 resin base material is injected into the stirring tank, the bottom ultrasonic vibrator is turned on, the ultrasonic frequency is 22 kHz, the power is 250 W, and the treatment is continuously performed for 4 min, and at the same time, the stirring tank is subjected to water bath preservation at 45 ℃, so that the molecular chain of the resin base material is relaxed to present a micro-flow state; S12. In the continuous ultrasonic environment, 0.3wt% of stearamide based on the mass of the resin base material is uniformly added to the resin base material, and the ultrasonic shear force is used to make the stearamide and the resin base material form a stable dispersion system; S13. A precision screw pump is used to inject benzoyl peroxide with a viscosity of 15 mPa・s as a curing agent into the system, the flow control accuracy is ±0.1 mL / min, and the weight ratio of the resin base material to the 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 outlet direction is consistent with the direction of the ultrasonic vibration wave peak, and the pushing rate is 5 mL / min; S14. The mixture enters the buffer tank, the vacuum air outlet on the top of the tank maintains a micro negative pressure of-0.008 MPa, the mixture stays in the tank for 0.8 min, and after eliminating the pulse fluctuation and defoaming, it is uniformly output to the mold.

[0027] S2. Stepwise curing S21. Preliminary curing: the mixture is injected into the mold cavity, the temperature is raised from room temperature to 78 ℃ at a rate of 6 ℃ / min, and maintained until the lens reaches a Shore D hardness of 35, and the curing time is about 480 s; S22. Temperature reduction relaxation: the temperature is reduced by 18 ℃ at a rate of 3 ℃ / min, and maintained for 3 min, so as 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; S23. Final curing: temperature rising to 118℃ at a rate of 4℃ / min, maintaining for 18 min to make the resin completely cross-linked; then temperature falling to 90℃ at a rate of 5℃ / min, 90℃ is 8℃ below the glass transition temperature of CR-39, maintaining micro positive pressure of 0.015 MPa in the cavity during the falling process to avoid air infiltration; S24. Pre-separation: controlling the mold to open to a gap of 0.4 mm at a rate of 0.08 mm / s, and inputting dry nitrogen at a flow rate of 4 L / min at 90℃ for 11 s to form an air cushion and carry away oligomers, thereby achieving pre-separation.

[0028] S3. Precise demolding S31. Gradient cooling: temperature falling from 90℃ to 60℃ at a rate of 5℃ / min, maintaining micro positive pressure of 0.015 MPa in the cavity to make the molecular chains of the lens stable and the gap between the lens and the mold stable at 0.4 mm; S32. Air pressure separation: injecting a pulse of dry compressed air with a dew point of -45℃ into the air inlet of the mold parting surface, and using stepwise pressure release; wherein 0.05 MPa is released for 0.11 s, 0.08 MPa is released for 0.3 s, and 0.05 MPa is released for 0.11 s, with a total pulse time of 0.52 s. Under the synergistic action of air pressure and stearic amide interfacial layer, the resin lens and the mold are separated without damage, and the lens automatically falls off.

[0029] Example 2: In this example, MR-10 resin is used as the resin base material to process optical lenses, and the specific steps are as follows: S1. Raw material mixing treatment S11. Inject the MR-10 resin base material into the stirring tank, turn on the ultrasonic vibrator at the bottom of the tank, and use an ultrasonic frequency of 24 kHz and a power of 200 W for continuous treatment for 3.5 min. At the same time, the stirring tank is subjected to water bath preservation at 48℃ to make the molecular chains of the resin base material relax and present a micro-flow state; S12. Under the continuous ultrasonic environment, uniformly add 0.25wt% stearic amide to the resin base material, and use ultrasonic shear force to make the stearic amide and the resin base material form a stable dispersion system; S13. Inject tert-butyl hydroperoxide with a viscosity of 25 mPa・s as a curing agent into the system through a precision screw pump, control the flow accuracy to be ±0.1 mL / min, and make the weight ratio of the resin base material to the curing agent be 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 outlet direction is consistent with the peak direction of the ultrasonic vibration, and the pushing rate is 7 mL / min; S14. The mixed material enters the buffer tank, the vacuum air outlet at the top of the tank maintains a micro negative pressure of -0.008 MPa, the mixed material stays in the tank for 0.6 min, and after eliminating pulse fluctuations and defoaming, it is uniformly output to the mold.

[0030] S2. Staged curing S21. Preliminary curing: injecting the mixed material into the mold cavity, increasing the temperature from room temperature to 75°C at a rate of 7°C / min, maintaining until the lens reaches a Shore D hardness of 34, and the curing time is about 460s; S22. Temperature reduction relaxation: reducing the temperature by 16°C at a rate of 2°C / min, maintaining for 2.5min, promoting the migration of stearic amide to the resin lens and mold interface, forming a low surface energy interface layer 2 on the lens body 1; S23. Final curing: increasing the temperature to 116°C at a rate of 3°C / min, maintaining for 16min, so that the resin is fully cross-linked; then reducing the temperature to 105°C at a rate of 4°C / min, which is 6°C below the MR-10 glass transition temperature, maintaining a slight positive pressure of 0.015MPa in the cavity during the temperature reduction process to avoid air infiltration; S24. Pre-separation: controlling the mold to slightly open to a gap of 0.35mm at a rate of 0.06mm / s, and introducing dry nitrogen at a flow rate of 3.5L / min at 105°C for 10s, forming an air cushion and carrying away oligomers to achieve pre-separation.

[0031] S3. Precise demolding S31. Gradient temperature reduction: reducing the temperature from 105°C to 61°C at a rate of 4°C / min, maintaining a slight positive pressure of 0.012MPa in the cavity, so that the molecular chains of the lens are fixed and the gap between the lens and the mold is stabilized at 0.35mm; S32. Air pressure separation: injecting a pulse of dry compressed air with a dew point of -45°C into the air inlet of the mold parting surface, using a staged pressure release; wherein 0.05MPa is released for 0.1s, 0.075MPa is released for 0.25s, and 0.05MPa is released for 0.11s, with a total pulse time of 0.45s. Under the synergistic action of air pressure and stearic amide interface layer, the resin lens and the mold are separated without damage, and the lens automatically falls off.

[0032] Example 3: In this embodiment, MR-8 resin is used as the base material to process optical lenses, and the specific steps are as follows: S1. Raw material mixing treatment S11. Inject the MR-8 resin base material into the stirring tank, turn on the ultrasonic vibrator at the bottom of the tank, and use an ultrasonic frequency of 20kHz and a power of 300W for continuous treatment for 5min, while the stirring tank is subjected to water bath preservation at 42°C to make the molecular chains of the resin base material relax and present a micro-flow state; S12. Under the continuous ultrasonic environment, uniformly add 0.4wt% stearic amide to the resin base material, and use the ultrasonic shear force to make the stearic amide and the resin base material form a stable dispersion system; S13. Injecting benzoyl peroxide with viscosity of 20 mPa・s as curing agent into the system by precision screw pump, controlling the flow accuracy of ±0.1 mL / min, and making the weight ratio of resin base material to curing agent 100:4; at this time, the ultrasonic parameter is adjusted to 30 kHz, 400 W, the screw pump outlet is located 6 mm below the liquid surface, the discharge direction is consistent with the peak direction of ultrasonic vibration, and the pushing rate is 10 mL / min; S14. The mixture enters the buffer tank, the vacuum air outlet on the top of the tank maintains-0.008 MPa micro negative pressure, the mixture stays in the tank for 1 min, after eliminating the pulse fluctuation and defoaming, it is uniformly output to the mold.

[0033] S2. Step curing S21. Preliminary curing: injecting the mixture into the mold cavity, increasing the temperature from room temperature to 81℃ at a rate of 8℃ / min, maintaining until the lens reaches Shore D hardness of 37, and the curing time is about 500 s; S22. Temperature reduction relaxation: reducing the temperature by 20℃ at a rate of 5℃ / min, maintaining for 4 min, promoting the migration of stearic amide to the interface between the resin lens and the mold, forming a low surface energy interface layer 2 on the lens body 1; S23. Final curing: increasing the temperature to 120℃ at a rate of 5℃ / min, maintaining for 20 min, so that the resin is completely crosslinked; then reducing the temperature to 100℃ at a rate of 6℃ / min, which is 10℃ lower than the glass transition temperature of MR-8; maintaining a micro positive pressure of 0.02 MPa in the cavity during the temperature reduction process to avoid air infiltration; S24. Pre-separation: controlling the mold to open to a gap of 0.5 mm at a rate of 0.1 mm / s, and introducing dry nitrogen at a flow rate of 5 L / min at 100℃, lasting for 12 s, to form an air cushion and carry away oligomers, achieving pre-separation.

[0034] S3. Precise demolding S31. Gradient temperature reduction: reducing the temperature from 100℃ to 59℃ at a rate of 6℃ / min, maintaining a micro positive pressure of 0.02 MPa in the cavity, so that the molecular chains of the lens are fixed and the gap between the lens and the mold is stabilized at 0.5 mm; S32. Air pressure separation: injecting dry compressed air pulse with dew point of-45℃ into the air inlet of the mold parting surface, using stepwise pressure release; among them, 0.055 MPa is released for 0.1 s, 0.09 MPa is released for 0.35 s, and 0.05 MPa is released for 0.11 s, the total pulse time is 0.56 s, under the synergistic action of air pressure and stearic amide interface layer, the resin lens and the mold are separated without damage, and the lens is automatically separated.

[0035] Comparative Example 1: Different from Example 1, the comparative example adopts conventional technology, and the steps are as follows: the resin base is mixed by traditional mechanical stirring without ultrasonic treatment, and no stearic acid amide is added; the curing agent is injected by a common pump and dispersed only by mechanical stirring; the curing process is a single temperature of 100℃ for 2h; and the mold is ejected mechanically.

[0036] Comparative Example 2: Different from Example 1, the comparative example does not add stearic acid amide in step S1, and the remaining steps are the same as those of Example 1.

[0037] Comparative Example 3: Different from Example 1, the comparative example only uses mechanical stirring for the resin base in step S1 without ultrasonic treatment, and the remaining steps are the same as those of Example 1.

[0038] Comparative Example 4: Different from Example 1, the comparative example directly cools to 60℃ after final curing, skips the step of slightly opening the mold and passing nitrogen, and directly performs step S31 gradient cooling, and the remaining steps are the same as those of Example 1.

[0039] Comparative Example 5: Different from Example 1, the comparative example does not perform the cooling relaxation step after S21 preliminary curing, and directly performs S23 final curing, and the remaining steps are the same as those of Example 1.

[0040] The lenses obtained from the examples and comparative examples are tested as follows, 3 samples are tested for each case, the average value is taken, and the results in Table 2 are obtained; The light transmittance and haze are tested as follows: according to GB / T2410-2008 “Determination of the Transmittance and Haze of Transparent Plastics”, a haze meter with a model number of NDH-5000 is used for testing, the sample is cleaned with anhydrous ethanol, and the light transmittance is measured at 3 points in the center and 1 / 3 away from the edge of the lens under the condition of 23℃±2℃ and a relative humidity of 50%±5%, with visible light of 380-780nm as the light source, and the average value is taken as the light transmittance. The haze is the ratio of the scattered light flux of the sample to the total transmitted light flux, and the average value of 3 points is taken.

[0041] 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 light lamp as the light source, and the refractive index of 1 point in the center and 4 points around the lens is measured under the condition of 20℃±0.5℃, and the difference between the maximum and minimum values is the refractive index deviation, wherein the 4 points around the lens are symmetrically located at 5mm away from the edge of the lens.

[0042] Appearance detection: Visual inspection: observe surface scratch, edge collapse and stain under 40W daylight lamp, 30-50cm from sample; Microscope inspection: observe fine defect with 10-50 times microscope, record defect size.

[0043] Table 2 Test results of lenses prepared from examples and comparative examples

[0044] Comparative example 1 adopts traditional process without ultrasonic treatment, leading to poor fluidity of resin base material, dispersion of curing agent by mechanical stirring only, uneven local curing, low light transmittance, high haze and large refractive index deviation, no stearic amide, mechanical ejection demolding, leading to serious appearance defects such as surface scratch and edge collapse, and overall performance degradation.

[0045] Comparative example 2 lacks low surface energy interface layer formed by stearic amide, leading to large adhesion between resin lens and mold, edge collapse during demolding, and significant increase in surface scratch rate; meanwhile, the absence of stearic amide affects the dispersion stability of the system, the haze is slightly higher than that of the examples, and the appearance performance decreases significantly.

[0046] Comparative example 3 does not use ultrasonic treatment, and the curing agent cannot be dispersed into droplets by mechanical stirring only, leading to large differences in local curing reaction, low light transmittance, high haze and large refractive index deviation; mechanical stirring introduces more air bubbles, leading to increased scattered light and further increasing haze, affecting optical performance; although the demolding step is complete, the optical performance is still significantly inferior to that of the examples.

[0047] Comparative example 4 lacks a pre-separation step, and nitrogen is not passed through the slightly opened mold after final curing, leading to local adhesion between the resin lens and the mold, surface scratching during demolding, torn edges, and increased appearance defect rate; although the optical performance is less affected, the physical damage caused by adhesion significantly reduces the product yield.

[0048] Comparative example 5 does not cool down after preliminary curing, and the internal stress of the resin is not released, and the stearic amide migration is insufficient, leading to increased refractive index deviation and slightly decreased light transmittance; the interfacial adhesion increases during demolding, and the edge micro-cracks and surface scratches increase, resulting in inferior comprehensive performance compared to the examples.

[0049] Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. An optical lens processing process, 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 machining process 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 machining process 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 machining process 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 machining process 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 machining process 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 machining process according to claim 5, characterized in that, In step S2, the temperature of the mold is raised from room temperature to 65-81℃ at a rate of 5-8℃ / min, the temperature of the preliminary cured product is then lowered at a rate of 1-5℃ / min, and then raised to 115-121℃ at a rate of 3-5℃ / min, and maintained at 115-121℃ for 15-20min, after the final curing is completed, the mold is cooled to 5-10℃ below the glass transition temperature of the resin at a rate of 4-6℃ / min, and the mold cavity is kept at a micro-positive pressure of 0.01-0.02MPa during the cooling process.

8. The optical lens machining process according to claim 7, characterized in that, In step S3, the temperature is continuously lowered to 59-61℃ at a rate of 4-6℃ / min from 5-10℃ below the glass transition temperature of the resin, and the mold cavity is kept at a micro-positive pressure of 0.01-0.02MPa during the cooling process.

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

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