Pretreatment of thermosetting spectacle lens waste for recycling

Abstract

This disclosure relates to a method suitable for pre-treating spectacle lens waste, including thermosetting spectacle lens material, for subsequent recycling processes.

Description

[Technical Field]

[0001] The present invention relates to a method suitable for pre-treating spectacle lens waste containing thermosetting materials for recycling spectacle material waste. [Background technology]

[0002] Today, a wide variety of plastic materials are used in the optical industry, particularly in the manufacture of eyeglass lenses. Plastic materials used in the optical industry can be broadly classified into thermosetting materials and thermoplastic materials.

[0003] During the manufacturing of final optical articles, various mixed material wastes are generated at different points in the manufacturing process, and these are currently mainly incinerated or sent to landfills. This waste is generated in different formulations, qualities, and quantities. It mainly includes discarded lenses, lens fragments, and grinding and abrasive waste. The disposal of the aforementioned types of waste has negative environmental and economic impacts.

[0004] Currently, direct recycling of plastic waste generated during the manufacture of eyeglass lenses or from the disposal of eyeglass lenses by customers is not possible, neither mechanically nor chemically. This is due to differences in the chemical and physical properties of the different materials contained in the waste, as well as the improper size of the waste and undesirable impurities. Therefore, pretreatment is necessary to bring the waste resin into the desired state.

[0005] Conventional technologies describe various recycling processes for the aforementioned materials, where it is important to distinguish between thermoplastics and thermosetting materials.

[0006] Thermoplastic materials such as polycarbonate, polyacrylate (e.g., PMMA), polyamide, and polycyclic olefins (COC, COP) can be melted under appropriate conditions, but they can also be melted and processed into new products. For example, the physical recycling of polycyclic olefins as optical resins is described in International Publication 2023 / 190013A1. U.S. Patent Application Publication 2021197421A, Chinese Patent Application Publication 117468107A, and U.S. Patent Application Publication 2013 / 0055926A1 also disclose methods for pre-treating and processing thermoplastic materials, but these are not applicable to thermosetting optical resins, which have different properties from thermoplastic materials.

[0007] Unlike thermoplastics, thermosetting materials are insoluble and cannot be melted. Therefore, the pretreatment and processing methods for thermoplastic materials disclosed in U.S. Patent Publication No. 2021197421A, Chinese Patent Publication No. 117468107A, and U.S. Patent Publication No. 2013 / 0055926A1 are not applicable to thermosetting optical resins, which have different properties from thermoplastics. Consequently, a different approach should be taken. For this polymer class, chemical recycling processes or vitrimerization processes that decompose the polymer to regenerate monomers or oligomers are the main options, while physical methods, such as those outlined in the aforementioned International Publication No. 2023 / 190013A1 brochure, are not applicable to thermosetting materials. International Publication No. 2021 / 157701A1 brochure discloses a method for recycling polythiourethane lenses. This method proceeds through pretreatment of the reactants, but this pretreatment does not control parameters that affect the conditions of the pretreatment process. Therefore, a considerable amount of impurities can be introduced during pretreatment, which is due to uncontrolled and harsh processing conditions. These unwanted impurities further complicate or render the subsequent separation process useless. Furthermore, an uncontrolled pretreatment process complicates subsequent processes and severely limits the applicability of the processing.

[0008] Chinese Patent Application Publication No. 103483620A and Romanian Patent Application Publication No. 137652A2 disclose the recycling of thermosetting optical resins, but regarding the pretreatment of the resin before recycling, both only describe that the resin is crushed. There is no recognition of the impact or importance of the pretreatment conditions on the subsequent recycling process.

[0009] Chinese Patent Application Publication No. 117757216A describes a pretreatment method for thermosetting waste from wind turbine blades, which involves crushing, processing with PVC, and adding binders and additives. However, this is not applicable to recycling spectacle lens waste into spectacle lens material that needs to meet specific requirements for spectacle lens material (yellowing, haze, transmittance, etc.). [Overview of the project] [Problems that the invention aims to solve]

[0010] Based on International Publication No. 2021 / 157701A1, the object of the present invention is to pre-treat spectacle lens waste, including thermosetting spectacle lens material, so that the pre-treated waste is suitable for subsequent recycling processes. In other words, the pre-treated material of the present invention is suitable not only for subsequent recycling options such as chemical recycling or vitrimerization applicable to thermosetting materials, but also for physical recycling which is not directly applicable to thermosetting materials. Furthermore, the inventors have found that by carefully pre-treating spectacle lens waste before providing it to subsequent recycling processes, additional filtration, separation, purification, etc. in the recycling process can be greatly simplified, and the properties of the resulting product are improved. In addition, additional steps such as sorting, rinsing and drying, magnetic separation and / or sieving can be greatly simplified by carefully performing the crushing step, thereby providing an easy and efficient pre-treatment method for the recycling of thermosetting spectacle lens waste. [Means for solving the problem]

[0011] The inventors have found that among the pretreatment processes, crushing has the greatest influence on the properties of the resulting material. That is, the parameters of crushing play an important role in the properties of the resulting product. In particular, among the crushing parameters, the feeding rate of the input waste, the average volume equivalent diameter of the input waste, the average volume equivalent diameter of the discharged waste, the rotational speed of the crusher, and the temperature during crushing were found to be important for the properties of the resulting pretreated material. Based on this, the present invention provides a method suitable for pretreatment of spectacle lens waste containing thermosetting materials, wherein the pretreatment comprises crushing the spectacle lens waste, and the crushing is carried out by specifying the feeding rate of the input waste, the average volume equivalent diameter of the input waste, the average volume equivalent diameter of the discharged waste, the rotational speed of the crusher (or crusher), and the temperature during crushing (or crusher). In one embodiment, the method according to the present invention may be a method for pretreatment of spectacle lens waste. In a further embodiment, the method according to the present invention may be a method for recycling spectacle lens waste, comprising pretreatment of spectacle lens waste and recycling the pretreated spectacle lens waste. In yet another further embodiment, the method according to the present invention may further include manufacturing spectacle lens material using the recycled spectacle lens waste. [Modes for carrying out the invention]

[0012] The term "eyeglass lens" refers to an ophthalmic lens that is worn in front of the eyeball but without contact with it (ISO 13666:2019(E)3.5.2), which is a lens intended to be used for the purpose of measuring, correcting and / or protecting the eye or to alter its appearance (ISO 13666:2019(E)3.5.1).

[0013] The term "eyeglass lens material" refers to the material used to manufacture eyeglass lenses, such as the material of the eyeglass lens substrate. Thermosetting eyeglass lens material can be any eyeglass lens material that functions as a thermosetting resin. For example, thermosetting eyeglass lens material may be, but is not limited to, polyallyl carbonate, e.g., polyallyl diglycol carbonate (PADC, e.g., CR39, CR330, CR607, CR630, RAV 700), polydiallyl isophthalate (e.g., KOC400), polyurethane (PUR), polyurethane / polyurea (PUR / PUA, e.g., Trivex, RAVolution), polythiourethane (PTU, e.g., MR6, MR7, MR8, MR10), and polyepisulfide (e.g., MR174, MGC 1.76), etc. Typical thermoplastic materials include polycarbonate (PC), polyacrylate (PMMA, e.g., Luxexel Pritoptical, SOLA Spectralite), polyamide (PA), and polycyclic olefin (COC, COP).

[0014] The term "eyeglass lens base material" refers to optical material pieces used in the manufacturing process of eyeglass lenses, namely, precursors to finished lenses (ISO 13666:2019(E)3.8.7), uncut lenses (ISO 13666:2019(E)3.8.8), or shaped lenses (ISO 13666:2019(E)3.8.9). A suitable precursor to a finished lens is, for example, a semi-finished lens blank, and the term "semi-finished lens blank" refers to an optical material piece with one side optically finished for the manufacture of eyeglass lenses (ISO 13666:2019(E)3.8.1).

[0015] The term "eyeglass lens material" refers to the material used to manufacture eyeglass lenses, such as the material for the base material of eyeglass lenses.

[0016] The term "waste" refers to materials, substrates, substances, semi-finished products, by-products, or finished products that are removed or discarded because they are no longer useful or are no longer needed. The term "eyeglass lens waste" refers to substrates, substances, semi-finished products, by-products, or finished products, etc., that are discarded during the lifecycle of eyeglass lenses or lens materials. Eyeglass lens waste may include discarded lenses, shavings, and / or manufacturing residues, such as residues from shaping, crushing, and grinding. Eyeglass lens waste may also include eyeglass lenses that are no longer needed due to damage or a change in the user's ophthalmic condition. The spectacle lens waste according to the present invention includes, but is not limited to, thermosetting spectacle lens materials such as polyallyl carbonate, for example polyallyl diglycol carbonate (PADC, e.g., CR39, CR330, CR607, CR630, RAV 700), polydiallyl isophthalate (e.g., KOC400), polyurethane (PUR), polyurethane / polyurea (PUR / PUA, e.g., Trivex, RAVolution), polythiourethane (PTU, e.g., MR6, MR7, MR8, MR10), and polyepisulfide (e.g., MR174, MGC 1.76), and preferably consists of these materials.

[0017] In this invention, the term "contains" means that various compositions, compounds, steps, etc., may be used collectively. Therefore, the term "contains" encompasses the more restrictive terms "basically derived from" and "consisting of." The terms "contains" and "includes" may be used synonymously.

[0018] The term "input waste" refers to spectacle lens waste that is used as starting material in the pretreatment process, particularly the grinding process, and is initially introduced into the process. The term "discharged waste" refers to the material obtained as a result of the pretreatment process, particularly the grinding process, and the material obtained from the process, i.e., "pretreated material."

[0019] The term "grinding" means changing a material into fine particles or powder by crushing it using a grinding system or grinder. This may also refer to pulverizing or crushing the material. Grinding can be carried out by any conventional means or device such as a grinder or mill known in the art. For example, mechanical mills such as cryomills, ball mills or toothed mills, hammer mills, knife mills, turbo mills, press grinding mills, etc. may be used. The term "grinding machine system" refers to an open or closed system equipped with a grinding machine.

[0020] The feed rate (Q) of the input waste means the rate at which the input waste is fed into the grinding process or grinder, and is defined in units of kg / min.

[0021] The average volume equivalent diameter (D) is the diameter of a sphere with the same volume as the size of the particles under consideration, and is defined in units of meters (m). The average volume equivalent diameter can be calculated by the following formula, and the average particle volume can be measured by any known method including the following.

Number

[0022] For example, the average particle volume can be calculated by the following formula.

Number

[0023] [[ID=​​​​​​​​​​​​​The rotational speed (V) of a crusher is the number of rotations of the crusher and is defined in revolutions per minute (rpm).

[0026] Even if grinding parameters are specified to obtain suitable properties for subsequent recycling processes, pretreatment under uncontrolled or coarsely controlled conditions may increase impurities, resulting in a product unsuitable for use as an eyeglass lens material. For example, uncontrolled conditions such as high temperature and large shear stress can cause undesirable side chemical reactions or physical changes due to oxidation, degradation, etc., leading to increased impurities or undesirable properties in the resulting product, making it difficult or impossible to recycle the material as an eyeglass lens material. The inventors have recognized that in order to obtain a suitable product with desirable properties for subsequent recycling processes, especially upcycling, i.e., a product suitable for manufacturing eyeglass lens materials, it is necessary to finely adjust the pretreatment conditions and control them holistically, taking into account other relevant factors.

[0027] Through numerous trials and various settings of grinding conditions, it has been found that by setting the feed rate of the input waste, the average volume equivalent diameter of the fed waste, the average volume equivalent diameter of the discharged waste, the rotation speed of the grinder, and the temperature during grinding to satisfy specific conditions, side reactions during pretreatment can be significantly reduced, process compatibility, i.e., compatibility with subsequent recycling processes such as chemical recycling or vitrimerization, can be improved, and the properties of the resulting product can be improved to suit subsequent recycling processes. Based on these findings, the present invention further provides a method suitable for pretreatment of spectacle lens waste containing thermosetting spectacle lens material for a recycling process, characterized in that the pretreatment includes grinding the spectacle lens waste to satisfy the following formula.

number

[0028] The technical importance in the above formula lies in maintaining a balance between the required grinding strength and the provided grinding strength in order to provide pre-treated material suitable for subsequent recycling processes, which is represented by the three coefficients Q, V, and D in / D out It depends greatly on that.

[0029] For example, the faster Q is, the stronger the grinding required (more material input), and the larger V is, the stronger the grinding provided (greater impact and shearing occurs). D shows the relationship between the required grinding strength and the size of the input and output materials. Simply put, D in High, D out The lower the value, the stronger the grinding required. In other words, to grind larger particles into smaller particles, a higher grinding strength is required. All three of these parameters are independent variables in the above formula, and this embodiment is based on the observation that the combination of variables that satisfy the above ranges in the formula leads to the characteristics of the thermosetting spectacle lens waste being desirable and suitable for subsequent recycling processes. The numerical range of each parameter is not specifically limited, nor can it be specifically limited, because as long as the above formula is satisfied, they can be flexibly set in various ways based on the general knowledge of those skilled in the art, depending on the type of equipment, the composition of the starting material, and other factors.

[0030] Eyeglass lens waste containing thermosetting eyeglass lens material, pre-treated by this method and satisfying the above formula, is not only applicable to various subsequent recycling processes, but also exhibits fewer impurities, which has been found to lead to reduced complexity and improved quality of the resulting material for subsequent recycling processes. For example, the highly complex and time-consuming purification, separation, and filtration processes of conventional methods can be significantly simplified or even reduced to a minimum.

[0031] The value obtained by formula I may be between 150 and 45,000, preferably between 1,500 and 20,000. If this value is too high, the provided grinding strength will be lower than the required grinding strength, thereby disrupting the balance between the provided grinding strength and the required grinding strength. The ground material may adhere to the inside of the grinder and clog, resulting in mechanical problems that hinder uniform heat transfer inside the grinder. This will lead to side reactions that increase unwanted temperature rises and impurities. On the other hand, if this value is too low, the provided grinding strength will be higher than the required grinding strength. In such cases, the material may be over-ground, and side reactions may occur.

[0032] The feeding rate (Q) of the input waste affects the required grinding strength. A faster feeding rate results in a higher required grinding strength. In this invention, the feeding rate should be determined by considering other parameters so as to satisfy Equation I. For example, if the feeding rate is too fast in light of other parameters, the required grinding strength will exceed the grinding strength provided, which will result in impurities and side reactions. In one embodiment, but not limited to, the feeding rate may be 1 to 100 kg / min, preferably 2 to 50 kg / min, and most preferably 2 to 30 kg / min.

[0033] Average volume equivalent diameter of input waste (D in ) and / or the average volume equivalent diameter of the discharged waste (D out) affects the required grinding strength. In this invention, the average volume equivalent diameter of the input waste should be determined by considering other parameters so as to satisfy Equation I. For example, if the average volume equivalent diameter of the input waste is too large in light of other parameters, or if the difference between the average volume equivalent diameters of the input waste and the discharged waste is too large, the required grinding strength will exceed the grinding strength provided, which will cause impurities and side reactions. If the average volume equivalent diameter of the input waste is too large compared to that of the discharged waste, it is also unfavorable in consideration of other parameters, as this will cause clogging of the material in the grinder, hindering heat transfer and resulting in mechanical problems and material overheating. On the other hand, if the average volume equivalent diameter is too small, very strong shear stress may be applied during grinding.

[0034] In one embodiment, the average volume-equivalent diameter of the input waste is 0.5 m or less, preferably 0.2 m or less, more preferably 0.1 m or less, and most preferably 0.01 m or more to 0.1 m or less. In one embodiment, the average volume-equivalent diameter of the discharged waste is 0.0001 m to 0.2 m, preferably 0.0001 m to 0.1 m, more preferably 0.0005 m to 0.01 m, and most preferably 0.0005 m to 0.002 m.

[0035] The rotational speed (V) of the grinder or grinder affects the grinding strength provided. In this invention, the rotational speed should be determined considering other parameters so as to satisfy Equation I. For example, if the rotational speed is too high in relation to other parameters, the grinding strength provided will exceed the required grinding strength, resulting in an imbalance. In such cases, the waste will be over-ground. In the opposite case, where the rotational speed is too slow, the ground material may adhere to and clog the inside of the grinder, resulting in mechanical problems, which in turn hinders uniform heat transfer inside the grinder.

[0036] In one embodiment, the rotational speed is set to 100 to 30,000 rpm, preferably 100 to 10,000 rpm, and more preferably 200 to 2,000 rpm.

[0037] Furthermore, it has been found that the temperature during the grinding process significantly affects the properties of the resulting product, such as the impurity content. Temperature control becomes much easier by using the key parameters in Equation I and ensuring that Equation I falls within the specified range described above. In conventional processes, the grinding temperature is often not considered a significant factor or is not finely controlled. However, in the case of spectacle lens waste, fine control of the temperature during grinding or the temperature of the grinder is particularly advantageous. In one embodiment, the temperature during grinding, or the temperature of the grinder, or the temperature of the grinding system should be at most 120°C, 100°C, or 80°C. If the temperature is higher than the specified range, unwanted side reactions such as oxidation, depolymerization, and repolymerization may occur. Optionally, the grinding system or grinder may be equipped with cooling means to lower the reaction temperature. The refrigerant may be, but is not limited to, liquid nitrogen, dry ice, gas (direct cooling), or water (indirect cooling).

[0038] In other embodiments, the pretreatment method of the present invention is: (i) A step of degassing the activated gas from the input waste before grinding, (ii) A step of crushing the input waste using an inert gas, (iii) A step of crushing the input waste using dry ice or liquid nitrogen, (iv) A step of crushing the input waste under vacuum, and (v) Step of crushing the input waste using an antioxidant. The process includes at least one step selected from the group consisting of the following:

[0039] These steps help avoid unwanted side reactions that could result in the introduction of impurities or contaminants.

[0040] By degassing eyeglass lens waste at high temperatures before crushing, moisture and active gases such as oxygen can be completely removed.

[0041] In one embodiment, degassing is performed using the following formula:

number

[0042] The inventors found that it is important to maintain the calculated degassing strength within the range specified by the three parameters (p, t, and T) mentioned above, and that these parameters are closely correlated in order to reach a desirable degassing strength.

[0043] Degassing at degassing strengths (Tt / p) below 80 did not adequately remove active gases and moisture, resulting in no substantial improvement in the quality of the pre-treated (ground) product. Degassing at higher degassing strengths (Tt / p) would be more efficient. In one embodiment, however, the degassing strength (Tt / p) may be 400 or less. The specific ranges of each parameter are not as significant as the ranges given for the formulas. Nevertheless, for the sake of greater understanding, the role and exemplary ranges of each parameter are provided. However, it is clear that the present invention is not limited to these.

[0044] The pressure during degassing provides the driving force for the gas in the grinding system and is lower than atmospheric pressure. The pressure can be, for example, 1 to 150 mbar, preferably 1 to 50 mbar.

[0045] The degassing time should be controlled to achieve other equilibrium states. Generally, longer degassing times may be advantageous, but after a certain period, the effect becomes minimal. Shorter degassing times result in insufficient removal of reaction gases and limit the effectiveness of degassing.

[0046] The temperature for degassing is also a driving force for degassing. The higher the temperature, the more flexible the polymer chains become, and therefore the easier it is to degas. For example, the temperature is between 20 and 120°C. Above 120°C, undesirable decomposition of the polymer chains can occur, potentially increasing impurities, while temperatures below room temperature lead to freezing of the polymer chains and more severe conditions, such as longer reaction times or higher vacuum.

[0047] In other embodiments, spectacle lens waste can be pulverized under vacuum for purposes similar to degassing. A preferred vacuum pressure may be less than 2 mbar.

[0048] In further embodiments, the spectacle lens waste can be pulverized using an inert gas such as nitrogen or argon to achieve similar results. In preferred embodiments, the input waste is pulverized using dry ice or liquid nitrogen to produce low-impurity discharge waste suitable for the manufacture of spectacle lens material. Dry ice or liquid nitrogen is particularly preferred because it also has the additional effect of lowering the pulverization temperature. In yet another further example, the spectacle lens waste is pulverized using an antioxidant. The antioxidant can be any commercially available product, such as a phenolic compound, but is not limited thereto. The amount of antioxidant can be 0.1% to 0.5% by weight. Too much of this amount may adversely affect the quality of the resulting pre-treated product.

[0049] Steps (i) to (v) described above may be performed individually or in combination with any one of the other steps, depending on the desired quality, waste characteristics, grinding conditions, type of grinder, configuration of the grinder, etc.

[0050] The present invention optionally includes a step of confirming the amount of impurities in the pre-treated material, i.e., the waste discharged from the grinding step. Impurities in the waste (discharged waste) can be detected by any method known in the art, such as FTIR, XPS, NMR, etc. The amount of impurities in the pre-treated (or ground) material should be such that the material can be recycled and used as spectacle lens material exhibiting desired properties such as a proper yellowness index.

[0051] In one embodiment, an increase in impurities in the pre-treated material (discarded material) can be identified using a change in the yellowness index. The yellowness index can be calculated using a standard method in the industry, namely, the method described in ISO 17223:2014:Plastics:Determination of yellowness index and change in yellowness index, ASTM E313-20:Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates.

[0052] The pre-treated material produced by this invention was found to have an increase in the yellowness index of less than 5 compared to the input waste. Pre-treatment of spectacle lens waste inevitably results in an increase in the yellowness index of the obtained material. If the change in the yellowness index of the pre-treated material is 5 or more, the pre-treated material will be difficult to upcycle and use as spectacle lens material. In other words, the amount of impurities is considered suitable for subsequent recycling processes for manufacturing spectacle lens material when the change in the yellowness index of the input waste and the output waste is less than 5.

[0053] In other embodiments, an increase in impurities in the pre-treated material (discharge material) can be confirmed using Raman spectroscopy. The spectacle lens waste pre-treated by the method according to the present invention exhibits an impurity content suitable for subsequent recycling processes. The inventors have found that the pre-treated material suitable for subsequent recycling processes for producing spectacle lens materials exhibits a specific peak increase within a specific peak range. In the case of spectacle lens waste containing polythiourethane, the pre-treated material (waste material) having the desired properties has a peak height ratio at 1220.5 cm -1 relative to 1206.5 cm -1 that increases by less than 4.5% compared to that of the input waste.

[0054] The materials pretreated according to the present invention, i.e., the waste materials, have been found to be suitable for various recycling processes using the different physical and / or chemical behaviors of spectacle lens waste. This includes physical recycling, chemical recycling, and vitrimerization. The term "recycling" refers to reprocessing spectacle lens waste into raw materials that can be reused in the manufacture of spectacle lens materials. Physical recycling may be recycling methods that use the different physical properties of spectacle lens waste, such as specific gravity separation and physical decomposition. Chemical recycling may be aminolysis, alcohollysis, and / or thiolysis. The pretreated materials of the present invention have been found to be particularly suitable for subsequent chemical recycling methods of polythiourethane. In one embodiment, spectacle lens waste containing polythiourethane pretreated by the method of the present invention is subsequently subjected to aminolysis and / or alcohollysis for recycling. For example, a decomposition agent such as a compound having active hydrogen (amine, alcohol, or thiol) is added (in excess) to pre-treated waste to release free thiols and urea, or urethane, or thiourethane therefrom. The released free thiols are then separated, purified, and recycled with high purity and yellowness suitable for eyeglass lens material. In a further embodiment, the urethane, urea, or thiourethane obtained from the above embodiment is decomposed by additional active amino acids to produce free amino acids, which in turn produce new urea or new urethane or thiourethane. The free amino acids are then separated, purified, phosgenated, and recycled as isocyanate.

[0055] After reprocessing, the eyeglass lens waste becomes recycled eyeglass lenses, which have been pre-treated according to the present invention before reprocessing.

[0056] Embodiments of the present invention will be described in more detail below. However, it should be understood that the following description is for illustrative purposes only and does not limit the present invention in any way. [Examples]

[0057] Example 1 A mixture of spectacle lens scrap and lens-shaped processing waste (hereinafter referred to as "waste") with an average volume equivalent diameter of 0.03 m was recovered without any treatment. The waste contained polythiourethane, polyepisulfide, and polyaryl diglycol carbonate. The waste was pulverized into small particles with an average volume equivalent diameter of 0.002 m using a knife mill in a pulverizing system with a rotation speed of 300 rpm and a feed rate of 10 kg / min to obtain discharged waste. The temperature of the pulverizing system was measured by a temperature sensor within the pulverizing system and was found to be 45.6°C. The changes in the yellowness index and the peak height ratio of the Raman spectrum between the input waste and the discharged waste produced as a powder were measured using the method described above. The change in the yellowness index from the input waste to the discharged waste was 2.2, and the change in the peak ratio of the Raman spectrum from the input waste to the discharged waste was 3.1%.

[0058] Spectra were acquired using a built-in microscope (BX43, Olympus) and a confocal Raman microscope with an electric XYZ stage (XploRA Plus, Horiba). A 100× objective lens (MPlanN, NA0.9, WD0.21mm, Olympus) was used for sample detection and spectrum acquisition. Raman scattering was generated using a 785nm laser diode and detected with a -60°C air-cooled charge-coupled detector. Raman measurements using a 1200 l / mm grating showed a range of 200–3400 cm⁻¹. -1 The spectral resolution across this spectral range is approximately 0.5 cm. -1 The laser power was approximately 10 mW. All spectra were obtained with an acquisition time of 8 seconds. The same method was used in the following examples and comparative examples.

[0059] The waste generated in Example 1 was found to be suitable for use in a subsequent recycling process for producing eyeglass lens material.

[0060] Comparative Example 1 The same waste as in Example 1 was crushed to the same size using the same crusher at the same feeding speed, but with the rotation speed reduced to 100 rpm. The crushing parameters in Example 2 do not satisfy Equation I. The crushing capacity is limited mainly due to the mismatch between the rotation speed and the feeding speed, which leads to malfunctions and mechanical problems. The temperature sensor in the crushing system shows that the temperature rose to 92.4°C. As a result, the change in the yellowness index from the input waste to the output waste was 5.2, and the change in the peak ratio of the Raman spectrum from the input waste to the output waste was 4.8%, which indicates that the output waste is not suitable for recycling as eyeglass lens material.

[0061] Comparative Example 2 The same waste as in Example 1 was crushed to the same size using the same crusher at the same rotational speed, but with the feed rate increased to 30 kg / min. The crushing parameters of Comparative Example 2 did not satisfy Equation I. Similar uncrushability to Comparative Example 1 was observed, and as a result, the temperature rose to 93.8°C. As a result, the change in the yellowness index from the input waste to the output waste was 5.4, and the change in the peak ratio of the Raman spectrum from the input waste to the output waste was 5.3%, indicating that the output waste is not suitable for recycling as eyeglass lens material.

[0062] Comparative Example 3 The same waste as in Example 1, except for an average volume equivalent diameter of 0.05 m, was crushed at the same feeding rate but with the rotation speed increased to 2500 rpm. The input waste was crushed into discharged waste with an average volume equivalent diameter of 0.01 m. The crushing parameters of Comparative Example 3 do not satisfy Equation I. Due to the strong shear stress at the high rotation speed, the crushing system was unable to maintain the temperature within the desired range. The temperature of the crushing system rose to 102.7°C. The crushing parameters of Comparative Example 3 do not satisfy Equation 1. In addition to the importance of delicately controlling the crushing parameters, as supported by Example 1, the poor results of Comparative Examples 1, 2, and especially 3 reflect that temperature is one of the important factors in the pretreatment.

[0063] As a result, the change in the yellowness index from input waste to output waste was 9.2, and the change in the peak ratio of the Raman spectrum from input waste to output waste was 10.3%, indicating that the output waste is not suitable for recycling as eyeglass lens material.

[0064] Example 2 Before grinding, the same waste material as in Example 1 was degassed at a pressure of 10 mbar and 80°C for 24 hours. The degassing strength according to Equation 2 was 192.

[0065] Subsequently, the degassed input waste was immediately ground under the same grinding conditions as in Example 1. The temperature of the grinding system was measured using a temperature sensor in the grinding chamber and was found to be 44.8°C. This indicates that the degassing step slightly lowers the temperature of the grinding system, which is advantageous for the purity of the resulting product.

[0066] The change in the yellowness index from the input waste to the output waste was 1.7, and the change in the peak ratio of the Raman spectrum from the input waste to the output waste was 2.6%. Compared to Example 1, both the change in the yellowness index and the change in the peak ratio were reduced. This confirms that the degassing step contributes to increasing the purity of the pre-treated material.

[0067] Example 3 The same waste material as in Example 1 was ground under the same grinding conditions as in Example 1, while adding 15% by weight of dry ice in 15 separate additions (1% each time). The temperature of the grinding system was 21.5°C, which is much lower than in Example 1.

[0068] The temperature reduction achieved by dry ice reduces side reactions that often occur at higher temperatures, thus decreasing impurities. Furthermore, the sublimation of dry ice creates an inert gas atmosphere inside the grinding system or grinder, limiting unwanted chemical reactions.

[0069] The change in yellowness index from input waste to discharged waste was 0.7, and the change in the peak ratio of the Raman spectrum from input waste to discharged waste was 1.1%. This is the lowest among all examples. Based on this, the use of dry ice during the pretreatment process is confirmed to be particularly advantageous in reducing impurities.

[0070] Example 4 The same waste material as in Example 1 was mixed with 0.25% by weight of 4,4'-thio-bis(6-tert-butyl-m-methylphenol) as an antioxidant before grinding.

[0071] The prepared input waste was then pulverized under the same pulverization conditions as in Example 1. The temperature of the pulverization system was 46.6°C.

[0072] The change in yellowness index from input waste to output waste was 1.9, and the change in the peak ratio of the Raman spectrum from input waste to output waste was 2.8%. Compared with Example 1, it is clear that the antioxidant contributed to reducing impurities in the pre-treated material. It is hypothesized that the antioxidant contributed to the reduction of impurities by removing reactants or by adding more reactive compounds to prevent oxidation of the spectacle lens waste, mainly by reacting with O2.

[0073] The results of the examples are summarized in the table below.

[0074] [Table 1]

Claims

1. A method suitable for pretreatment of spectacle lens waste containing thermosetting spectacle lens material, A method comprising crushing the aforementioned eyeglass lens waste, wherein the aforementioned eyeglass lens waste is input waste, The crushing method is characterized by specifying the feeding speed of the input waste, the average volume equivalent diameter of the input waste, the average volume equivalent diameter of the discharged waste, the rotation speed of the crusher, and the temperature during crushing.

2. The grinding process is as follows: [Math 1] (In the formula, Q is the feeding rate (kg / min) of the input waste, D ｉｎ This is the average volume equivalent diameter (m) of the aforementioned input waste. D ｏｕｔ This is the average volume equivalent diameter (m) of the aforementioned waste, and V is the rotational speed (rpm) of the pulverizer. The method according to claim 1, characterized in that it is carried out in such a way as to satisfy the requirements.

3. The method according to claim 1 or 2, characterized in that the temperature during grinding is maintained at 120°C or lower, 100°C or lower, or 80°C or lower.

4. D ｉｎ The method according to any one of claims 1 to 3, characterized in that the length is 0.5 m or less, or 0.2 m or less, or 0.1 m or less, or 0.01 m or more and 0.1 m or less.

5. D ｏｕｔ The method according to any one of claims 1 to 4, characterized in that is 0.0001m to 0.2m, or 0.0001m to 0.1m, or 0.0005m to 0.01m, or 0.0005m to 0.002m.

6. (i) A step of degassing the active gas from the input waste before grinding, (ii) A step of crushing the input waste using an inert gas, (iii) A step of crushing the input waste using dry ice or liquid nitrogen, (iv) The step of crushing the input waste under vacuum, (v) Step of crushing the input waste using an antioxidant. The method according to any one of claims 1 to 5, characterized by comprising at least one step selected from the group consisting of the following.

7. The method according to any one of claims 1 to 6, characterized in that the crushing is carried out using dry ice.

8. The following equation II: [Math 2] (In the formula, p is the pressure (mbar) during degassing. t is the degassing time (hours), and T is the degassing temperature (°C). The method according to claim 6, characterized by degassing at a certain intensity.

9. The method according to claim 6 or 8, characterized in that the degassing temperature is in the range of 20°C to 120°C, or 25°C to 100°C, or 40°C to 80°C.

10. The method according to any one of claims 1 to 9, further characterized by comprising the step of confirming the amount of impurities in the discharged waste, wherein the amount of impurities is determined to be suitable for a subsequent recycling process for manufacturing spectacle lens material when the change in the yellowness index of the input waste and the discharged waste is less than 5, as measured according to ASTM E313-20.

11. The aforementioned spectacle lens waste contains polythiourethane, and the amount of the impurity is measured by Raman spectroscopy, at 1206.5 cm³ of the discharged waste. －１ 1220.5 cm －１ The method according to claim 10, characterized in that when the peak height ratio at increases by less than 4.5% compared to that of the input waste, it is determined to be suitable for a subsequent recycling process for manufacturing eyeglass lens material.

12. The method according to any one of claims 1 to 11, characterized in that the aforementioned spectacle lens waste includes polythiourethane spectacle lens material.

13. A suitable method for recycling eyeglass lens waste, The aforementioned eyeglass lens waste is pre-treated by the method described in any one of claims 1 to 12, The aforementioned pre-treated eyeglass lens waste is recycled by utilizing the physical and / or chemical behavior of the eyeglass lens waste. A method characterized by...

14. The method according to claim 13, characterized in that the recycling is carried out by at least one method selected from the group consisting of vitrimerization, aminolysis, alcoholization, and thiolysis.

15. The method according to claim 13 or 14, characterized by further manufacturing an eyeglass lens material using the aforementioned pre-treated and recycled eyeglass lens waste.

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