CN116514394A - Fluorophosphate optical glass, its preparation method and optical element - Google Patents

Abstract

The invention provides a fluorophosphate optical glass, a preparation method thereof and an optical element. Fluorophosphate optical glass contains the following components in terms of compounds: Al(PO ₃ ) ₃ : 5% to 12%; AlF ₃ : 22% to 33%; BaF ₂ : 7.5% to 15%; SrF ₂ : 20% ～30%; CaF ₂ : 20%～30%; MgF ₂ : 2%～7%; YF ₃ : 0.5%～8%; LiF: 0.05%～0.45%; The refractive index n _d of salt optical glass is 1.43-1.46, and the Abbe number υ _d is 90-100. The fluorophosphate optical glass of the present invention has a sufficiently high internal transmittance in the visible light range. Moreover, the fluorophosphate glass of the present invention not only has low cost, but also has good chemical stability and coloring degree; the glass transition temperature is low, which is beneficial to precision molding.

Description

Fluorophosphate optical glass, its preparation method and optical element

technical field

The invention relates to a fluorophosphate optical glass, a preparation method thereof and an optical element, belonging to the field of optical glass.

Background technique

Fluorophosphate optical glass with low refractive index and low dispersion is widely used in the lens module of optical instruments for high-precision chromatic aberration correction because of its low dispersion characteristics and the superior characteristics of eliminating the special dispersion of the secondary spectrum. Indispensable component material in the design. In recent years, with the rapid development of digitalization and high precision of optical equipment, the imaging pixels are increasing day by day, so the requirements for resolution are also getting higher and higher.

The optical glasses disclosed in patent applications CN102745899A and CN1931761A all contain more than 5% P ⁵⁺ , and too much introduction of P ⁵⁺ will inevitably introduce more O ^2- , resulting in increased dispersion, and cannot obtain lower dispersion value.

Patent application CN102674689A discloses fluorophosphate optical glass, wherein the content of Zn ²⁺ is 0.5-15%, and Zn ²⁺ has a larger ion radius, too much introduction of Zn ²⁺ will destroy the network structure of the glass and reduce the Crystallization properties, chemical stability and degree of coloration. In addition, if Zn ²⁺ is introduced by Zn(PO ₃ ) ₂ , more O ^2- will inevitably be introduced, resulting in increased dispersion, but a lower dispersion value cannot be obtained.

In the fluorophosphate optical glass disclosed in patent application CN101544468B, the molar ratio of O ^2- /P ⁵⁺ is greater than 3.5, and more O ^2- is introduced, resulting in increased dispersion, but cannot obtain a lower dispersion value. The molar ratio of O ²⁻ /P ⁵⁺ in the present invention is 3.

The fluorophosphate optical glass disclosed in the patent application CN106904831A contains 0.5% to 8% of LiF. Because the radius of Li ⁺ is small, too much Li ⁺ will lead to a sharp decline in the alkali resistance of the glass, and the degree of wear will deteriorate, seriously It affects the subsequent processing and coating process of optical glass lenses, and at the same time, the devitrification performance becomes worse, and the stripes caused by devitrification during the melting process are serious, which greatly reduces the yield of glass.

Contents of the invention

The problem to be solved by the invention

The object of the present invention is to provide a kind of fluorophosphate optical glass and its preparation method and optical element. The refractive index n _d of the fluorophosphate optical glass is 1.43-1.46, and the Abbe number υ _d is 90-100. The fluorophosphate optical glass has good chemical stability, high visible light transmittance and low glass transition temperature, and can eliminate the defects of high melting temperature and difficult control of volatilization streaks in the existing optical glass.

Further, the present invention also provides a preparation method of fluorophosphate optical glass, which is simple and easy to obtain raw materials, and can realize stable mass production at the same time.

solutions to problems

The invention provides a kind of fluorophosphate optical glass, which comprises the following components in terms of compounds:

Al(PO ₃ ) ₃ : 5% to 12%, preferably 6% to 10%;

AlF ₃ : 22% to 33%, preferably 23% to 30%;

BaF ₂ : 7.5% to 15%, preferably 9% to 13%;

SrF ₂ : 20% to 30%, preferably 22% to 29%;

CaF ₂ : 20% to 30%, preferably 22% to 28%;

MgF ₂ : 2% to 7%, preferably 2% to 5%;

YF ₃ : 0.5% to 8%, preferably 0.5% to 6%;

LiF: 0.05% to 0.45%, preferably 0.1% to 0.35%;

The above percentages are all percentages by mass;

The refractive index n _d of the fluorophosphate optical glass is 1.43-1.46, and the Abbe number υ _d is 90-100.

According to the fluorophosphate optical glass of the present invention, wherein, in terms of weight percentage, the ratio BaF ₂ /CaF 2 of the content of BaF ₂ to the content of CaF ₂ is 0.35-0.72, _preferably 0.36-0.64; and/or, BaF The ratio BaF ₂ /(MgF ₂ +CaF ₂ ) of the content of ₂ to the sum of the contents of MgF ₂ and CaF ₂ is 0.3-0.64, preferably 0.32-0.56; and/or,

The ratio Al(PO ₃ ) ₃ /LiF of the content of Al(PO ₃ ) ₃ to the content of LiF is 13-180, preferably 13-150.

According to the fluorophosphate optical glass of the present invention, wherein the composition of the fluorophosphate optical glass does not contain P ₂ O ₅ , NaF, KF, SnF ₄ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ At least one of O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , GeO ₂ , CaO, BaO, SrO, and MgO.

According to the fluorophosphate optical glass of the present invention, wherein, the crystallization upper limit temperature L _t of the fluorophosphate optical glass is lower than 680° C., and the glass transition temperature T _g is lower than 440° C.; and/or,

The devitrification resistance T _g /L _t of the fluorophosphate optical glass is greater than 0.64.

According to the fluorophosphate optical glass of the present invention, λ ₈₀ of the coloring degree λ ₈₀ /λ ₅ of the fluorophosphate optical glass is 310nm or less, and λ ₅ is 190nm or less.

According to the fluorophosphate optical glass of the present invention, wherein the specific gravity of the fluorophosphate optical glass is 3.80 g/cm ³ or less.

According to the fluorophosphate optical glass of the present invention, wherein, the alkali resistance R _OH (S) of the fluorophosphate optical glass is grade 4 or above; and/or

The abrasion degree F _A of the fluorophosphate optical glass is 455 or less.

The present invention also provides a method for preparing the fluorophosphate optical glass according to the present invention, which includes: weighing each component according to the proportion, mixing them uniformly and then melting them, and during the melting process, making the volatile gas fully escape; preferably, the temperature of the smelting is 800-900°C; and then poured or leaked into the forming mold, or directly pressed into shape.

According to the preparation method of the present invention, after the smelting, it also includes, in a closed environment, raising the temperature to 900-1000°C and turning on the stirrer for stirring, and the stirring time is controlled at 3-8h; the stirring is completed Afterwards, raise the temperature to 1000-1050°C and keep it warm for 4-9 hours for clarification to make the bubbles fully float up, and then lower the temperature to 600-700°C.

The present invention also provides an optical element comprising the fluorophosphate optical glass according to the present invention.

The effect of the invention

The fluorophosphate optical glass of the present invention has a sufficiently high internal transmittance in the visible light range. Moreover, the fluorophosphate glass of the present invention not only has low cost, but also has good chemical stability and coloring degree; the glass transition temperature is low, which is conducive to precision molding; its specific gravity is low, which reduces the weight of glass components and optical systems ; It has excellent achromatic performance, which can improve the imaging quality of the optical system; at the same time, the crystallization temperature is low, making it easier to achieve mass production.

Furthermore, the preparation method of the fluorophosphate optical glass of the present invention is simple and feasible, the raw materials are easy to obtain, and are suitable for mass production.

Detailed ways

Various exemplary embodiments, features, and aspects of the invention are described in detail below. The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments.

In addition, in order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. It will be understood by those skilled in the art that the present invention may be practiced without certain of the specific details. In other instances, methods, means, devices and steps well known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the present invention should be understood as including inevitable systematic errors in industrial production.

In this specification, the meaning expressed by "may" includes the meaning of performing certain processing and not performing certain processing.

In this specification, references to "some specific/preferred embodiments", "other specific/preferred embodiments", "embodiments" and the like refer to specific elements described in relation to the embodiments (for example, A feature, structure, property, and/or characteristic) is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

In this specification, the numerical range represented by "numerical value A - numerical value B" means the range which includes numerical value A and B of an end point.

In the present specification, when "normal temperature" and "room temperature" are used, the temperature may be 10 to 40°C.

The present invention firstly provides an optical glass, which comprises the following components in terms of compounds:

Al(PO ₃ ) ₃ : 5% to 12%, preferably 6% to 10%;

AlF ₃ : 22% to 33%, preferably 23% to 30%;

BaF ₂ : 7.5% to 15%, preferably 9% to 13%;

SrF ₂ : 20% to 30%, preferably 22% to 29%;

CaF ₂ : 20% to 30%, preferably 22% to 28%;

MgF ₂ : 2% to 7%, preferably 2% to 5%;

YF ₃ : 0.5% to 8%, preferably 0.5% to 6%;

LiF: 0.05% to 0.45%, preferably 0.1% to 0.35%;

The above percentages are all percentages by mass;

The refractive index n _d of the fluorophosphate optical glass is 1.43-1.46, and the Abbe number υ _d is 90-100.

The raw material introduction mode adopts various forms capable of introducing the compound in its corresponding content. In the following description, the content of each component is expressed in mass percentage.

Al(PO ₃ ) ₃ is an essential component for introducing Al, P, O into glass. Al, P, and O are the main elements constituting the glass skeleton, which can promote the formation of stable glass and improve the mechanical properties and chemical durability of glass. When the content of Al(PO ₃ ) ₃ is lower than 5%, the crystallization tendency of the glass will be increased, and the mechanical properties and stability will be deteriorated, while when the content of Al(PO ₃ ) ₃ is higher than 12%, the refractive index and dispersion will increase. Large, can not obtain low refraction, low dispersion optical glass. Therefore, the content of Al(PO ₃ ) ₃ can be controlled to be 5%-12%, preferably 6%-10%.

The two elements (aluminum and fluorine) introduced by AlF ₃ are also components that constitute the glass network skeleton, and fluorine is also a key component to reduce product dispersion and increase the Abbe number _υd . AlF ₃ is effective for improving the devitrification resistance and chemical stability of glass, and is also of great significance for improving the mechanical properties and linear expansion coefficient of glass. In the glass system of _the present invention, when the content of _AlF3 is lower than 22%, it is difficult to achieve the goal of increasing the Abbe number _υd due to the reduction of fluorine in the glass, that is, it is difficult to realize the matching relationship of nd and _υd ; When the AlF ₃ content is higher than 33%, the transition temperature Tg of the glass will increase significantly, resulting in an increase in the forming temperature. In addition, the excessive AlF ₃ content will also increase the opacity tendency of the glass, increase the brittleness, and wear. degree increases. Therefore, the content of AlF ₃ is 22% to 33%, preferably 23% to 30%.

BaF ₂ can effectively adjust the refractive index of glass and improve the crystallization performance of glass. When the content of BaF ₂ is less than 7.5%, these effects cannot be sufficiently obtained. When the content of BaF ₂ is higher than 15%, the refractive index of the glass will be excessively increased, making it difficult to achieve the desired optical properties, and at the same time, the chemical stability of the glass will be reduced. In the present invention, the content of BaF ₂ can be controlled to be 7.5%-15%, preferably 9%-13%.

CaF ₂ can reduce the dispersion of the glass and improve the stability of the glass. When the content of CaF ₂ is less than 20%, these effects cannot be sufficiently obtained. When the content of CaF ₂ is higher than 30%, the glass cannot fully achieve the expected optical properties, and at the same time, the chemical stability of the glass will be reduced, and the crystallization tendency of the glass will be increased. In the present invention, the content of CaF ₂ can be controlled to be 20%-30%, preferably 22%-28%.

Further, the inventors found that when the ratio BaF ₂ /CaF ₂ is too low, the anti-devitrification ability and chemical stability of the glass decrease; when the ratio BaF ₂ /CaF ₂ is too high, the specific gravity of the glass increases, making it difficult to achieve Lightweight purpose. Therefore, in the present invention, the BaF ₂ /CaF ₂ value is limited to 0.35-0.72, preferably 0.36-0.64.

SrF ₂ can effectively adjust the refractive index of glass and improve the crystallization performance of glass. When the content of SrF ₂ is less than 20%, these effects cannot be sufficiently obtained. When the content of SrF ₂ is higher than 30%, the glass cannot fully achieve the expected optical properties, and the chemical stability of the glass will also be reduced. In the present invention, the content of SrF ₂ can be controlled at 20%-30%, preferably 22%-29%.

MgF ₂ is added as an optional component in the present invention. MgF ₂ can reduce the dispersion and refractive index of the glass, and at the same time can improve the chemical stability of the glass. When the content of MgF ₂ is less than 2%, low dispersion and refractive index cannot be formed. However, when the content of _MgF2 is higher than 7%, the crystallization performance of the glass will be deteriorated. Therefore, in the present invention, the amount of MgF ₂ can be controlled at 2%-7%, preferably 2%-5%.

Furthermore, the inventors found that the value of BaF ₂ /(CaF ₂ +MgF ₂ ) is closely related to the crystallization performance and chemical stability of the glass. When the value of BaF ₂ /(CaF ₂ +MgF ₂ ) is too low, the anti-devitrification performance of the glass will be deteriorated, and the chemical stability will also be deteriorated; when the value of BaF ₂ /(CaF ₂ +MgF ₂ ) is too high , the specific gravity of the glass increases, and the dispersion of the glass increases, making it impossible to form a low dispersion. Therefore, in the present invention, the value of BaF ₂ /(CaF ₂ +MgF ₂ ) is limited to 0.3-0.64, preferably 0.32-0.56.

YF ₃ is beneficial to adjust the optical properties of glass such as refractive index and dispersion, and can obviously improve the chemical stability of glass, increase the molding viscosity of glass, and is beneficial to the molding of glass. However, if it is introduced in excess, the devitrification resistance of the glass will be reduced, the refractive index and dispersion will be greatly increased, and the expected optical properties cannot be achieved. Therefore, in the present invention, the amount of YF ₃ can be controlled at 0.5% to 8%, preferably 0.5% to 6%.

The inventors have found that LiF can reduce the surface tension during the glass melting process in the present invention and effectively eliminate the bubble problem in fluorophosphorus glass. Therefore, LiF exists as an essential component in the invention, but when its content exceeds 0.45%. , due to the characteristics of Li ⁺ , the chemical stability of the glass will decrease, and at the same time, the crystallization performance of the glass will deteriorate, and the degree of wear will increase. Therefore, in the present invention, the amount of LiF can be controlled between 0.05%-0.45%, preferably 0.1%-0.35%.

Further, the inventors found that the Al(PO ₃ ) ₃ /LiF ratio is closely related to the crystallization performance of the glass, and when the Al(PO ₃ ) ₃ /LiF is too low, the crystallization performance of the glass becomes worse; when When the Al(PO ₃ ) ₃ /LiF is too high, the refractive index and dispersion will be greatly increased, and the effects of low refraction and low dispersion cannot be achieved, and it is difficult to eliminate bubbles and foreign matter during the melting process. Therefore, in the present invention, the ratio of Al(PO ₃ ) ₃ /LiF is controlled to be 13-180, preferably 13-150.

The fluorine (F) content in the glass is effective in reducing the refractive index _nd and dispersion of the glass. If the fluorine (F) content is too small, the refractive index and dispersion tend to increase, and the goals of low refractive index and low dispersion cannot be achieved. Conversely, if the fluorine (F) content is too much, the ionic bond in the glass will increase, and the characteristics of the small ionic bond energy will lead to the instability of the glass skeleton, which will make the glass more likely to devitrify, and the fluorine ( F) Too much content will also increase the abrasiveness of the product, and an excessively large abrasiveness value is not conducive to tolerance control in the process of fine grinding and polishing of glass. In the present invention, the fluorine (F) in the glass is introduced by composite addition of AlF ₃ , BaF ₂ , CaF ₂ , SrF ₂ , MgF ₂ , LiF, and other fluorides are not artificially introduced in the present invention.

The inventors have discovered that the refractive index and dispersion of fluorophosphate glasses are related to the oxygen to fluorine ratio (O/F) in the glass. The larger the oxygen-fluorine ratio (O/F), that is, the higher the oxygen content, the higher the refractive index of the glass and the greater the dispersion, and a reasonable oxygen-fluorine ratio (O/F) is particularly important for improving the opacification resistance of the glass. In the present invention, the content and ratio of the above-mentioned oxides and fluorides are used to control the oxygen-fluorine ratio (O/F) in the glass.

The hydroxyl (OH) content in glass is closely related to the alkali resistance of glass. The hydroxyl group in the glass will destroy the network structure of the glass and reduce the stability of the glass skeleton. When it is eroded by alkaline solution, the structure is more easily damaged, which will greatly reduce the alkali resistance of the glass. Therefore, in the present invention, the hydroxyl groups in the glass are reduced as much as possible.

Furthermore, the composition of the fluorophosphate optical glass of the present invention does not contain P ₂ O ₅ , NaF, KF, SnF ₄ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , At least one of Ta ₂ O ₅ , GeO ₂ , CaO, BaO, SrO, and MgO is preferably not contained.

In the present invention, the crystallization upper limit temperature L _t of the fluorophosphate optical glass is below 680°C, and the glass transition temperature _Tg is below 440°C; and/or, the devitrification resistance of the fluorophosphate optical glass is T _g /L _t is greater than 0.64. In the coloring degree λ ₈₀ /λ ₅ of the fluorophosphate optical glass, λ ₈₀ is less than 310nm, and λ ₅ is less than 190nm. The specific gravity of the fluorophosphate optical glass is below 3.80 g/cm ³ . The alkali resistance R _OH (S) of the fluorophosphate optical glass is grade 4 or above; the abrasion degree F _A of the fluorophosphate optical glass is below 455.

Further, the present invention also provides a method for preparing the fluorophosphate optical glass according to the present invention, which is characterized in that it includes: weighing and mixing each component according to the proportion and then melting them, and during the melting During the process, the volatile gas is fully released; preferably, the melting temperature is 800-900° C.; and then poured or leaked into a molding mold, or directly pressed into shape.

In the present invention, as soon as the glass powder is put into the crucible, a large amount of volatiles will be produced due to the strong volatility of fluorides. Due to the large amount of volatilization of fluorides, the hydroxyl groups in the glass will be taken out in the form of _H2O , which can greatly reduce The hydroxyl content in the glass, therefore, the manufacturing process of the optical glass of the present invention needs to be handled in an open way during the melting process, so that the volatile gas can fully escape.

Further, after the smelting, it also includes raising the temperature to 900-1000°C and turning on the stirrer for stirring, and the stirring time is controlled at 3-8h; after the stirring is completed, the temperature is raised to 1000-1050°C and kept for 4-9h, and Clarify, make the bubbles fully float, and then lower the temperature to 600-700 °C.

Specifically, after the smelting is completed, it needs to be sealed during the stages of stirring, homogenizing, clarification, and cooling down. At this time, the glass undergoes a large amount of volatilization during the smelting process, and the volatilization amount is greatly reduced. If it is opened, the H ₂ O in the air will be released again In the molten glass, the content of hydroxyl groups increases, so the optical glass manufacturing process of the present invention needs to be sealed during the stages of stirring, homogenizing, clarifying, and cooling out of the furnace.

Fluorophosphate glass has strong volatility because it contains a large amount of fluorine. In order to reduce the optical inhomogeneity (stripe) and environmental pollution caused by the volatilization of fluorine on the glass surface, it is preferred to use it in the production of fluorophosphate glass A cooling cover plate is added on the upper surface of the forming mold where the molten glass flows, and the inert gas is passed through the cooling cover plate to the surface of the molten glass, so that the molten glass is cooled and formed as soon as possible. In addition, in order to prevent the glass from corroding the melting crucible, it is preferred to melt in a non-reducing atmosphere. During specific operations, oxygen can be introduced into the melting crucible or an oxidation melting pool can be added.

In addition, the present invention also provides an optical element comprising the fluorophosphate optical glass according to the present invention. Optical elements can be produced by one-time or two-time pressing of fluorophosphate optical glass, and the optical elements can be used in the optical systems of various optical instruments.

EXAMPLES The embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be considered as limiting the scope of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

Examples 1-20 in the table are typical experiments for obtaining fluorophosphate optical glass whose refractive index n _d is 1.43-1.46 and Abbe number υ _d is 90-100 according to the present invention.

Examples 1-20

Calculate, weigh and mix the components in the following Table 1, Table 2, Table 3 and Table 4 according to the specified ratio, and put them into a crucible made of platinum for melting at a temperature of 850°C. During the melting process, the crucible is open. to allow the gas to fully escape; after the raw materials are melted into molten glass, in a closed environment, raise the temperature to 950°C and turn on the platinum stirrer to stir and homogenize, the stirring time is controlled at 5h, after the stirring is completed , raise the temperature to 1000°C and keep it warm for 6 hours, clarify and make the bubbles fully float up, then lower the temperature to 750°C and pour or leak into the forming mold, and add the above-mentioned cooling cover on the forming mold to make the inert The gas passes through the cooling cover plate to the surface of the molten glass to solve the problem of volatilization streaks caused by fluorine loss. Finally, the optical glasses or optical elements of Examples 1-20 are obtained through annealing and processing.

Comparative Examples A-C

The raw materials corresponding to the components in the following Table 4 were weighed according to the specified proportions, and prepared by the same preparation method as in Examples 1-20 to obtain the optical glasses of Comparative Examples A, B, and C.

comparative example D

The raw materials corresponding to the components of Example 1 are weighed according to the specified ratio. The difference between Comparative Example D and Example 1 is that the smelting process is sealed. , and the rest are identical.

Comparative Example E

The raw materials corresponding to the components of Example 1 are weighed according to the specified ratio. The difference between Comparative Example E and Example 1 is that the smelting process is sealed, and after the smelting is completed, it is also sealed in the stages of stirring, homogenization, clarification, and cooling. Processing, the rest is exactly the same.

Performance Testing

Various properties of the obtained fluorophosphate optical glass were measured by the following methods.

According to the test method of GB/T7962.1-2010, the refractive index nd and the Abbe number υd of the fluorophosphate optical glass are measured.

The short-wave transmission spectral characteristics of optical glass are expressed by coloring degree λ ₈₀ /λ ₅ . λ ₈₀ refers to the corresponding wavelength when the spectral transmittance reaches 80%, and λ ₅ refers to the corresponding wavelength when the spectral transmittance reaches 5%. According to JOGIS02-2003 "Measurement Method of Coloring Degree of Optical Glass" of Japan Glass Industry Association, the light transmittance of glass with a thickness of 10 ± 0.1 mm after parallel face-to-face grinding was measured. It should be noted that when detecting, since the lower limit of measurement of _λ5 is 190nm, the measurement results of _λ5 are all below 190nm.

According to the test method of GB/T7962.12-2010, the internal transmittance (τ ₁₀ , sample thickness 10±0.1mm) at wavelengths of 700nm, 400nm and 300nm was measured.

According to the test method of GB/T7962.20-2010, the specific gravity of the obtained optical glass is tested.

The transition temperature T _g of the obtained optical glass was tested according to the test method of GB/T7962.16-2010.

L _t is the liquidus temperature, that is, the upper limit temperature of crystallization. The test is carried out by DTA (differential thermal analysis) method, and the temperature corresponding to the highest heat absorption peak in the DTA curve is L _t .

According to the test method of GB/T7962.19-2010, the degree of abrasion F _A of the obtained optical glass is tested.

The alkali-resistant stability of optical glass is expressed by R _OH (S). The test is to immerse a six-sided polished sample with a size of 40mm×40mm×5mm in a well-stirred, constant temperature of 50°C±3°C and a concentration of 0.01 mol/L sodium hydroxide solution for 15 hours.

The hydroxyl content in the glass cannot be quantitatively tested, but the hydroxyl group has an obvious absorption peak in the 3000nm band, so in the present invention, the content of the hydroxyl group in the glass is characterized by testing the 3000nm transmittance of the glass. According to the test method of GB/T7962.12-2010, the internal transmittance (τ ₁₀ , sample thickness 10±0.1mm) at the wavelength of 3000nm was measured.

Glass composition and performance parameter of table 1 embodiment 1-6

Glass components and performance parameters of table 2 embodiment 7-12

Glass composition and performance parameter of table 3 embodiment 13-18

Glass components and performance parameters of Table 4 Examples 19-20 and Comparative Examples A, B, and C

The performance parameter of table 5 embodiment 1 and comparative example D, E

It can be seen from Examples 1-20 that the present invention preferably uses the introduction of P ₂ O ₅ in the form of Al(PO ₃ ) ₃ , which has the advantage of greatly reducing the number of production abnormalities and making the product performance more stable and controllable. When the same and expected optical constants are achieved, the glass of the embodiment has higher chemical stability and lower glass transition temperature than the comparative example, and the lower glass transition temperature indicates that the product is more suitable for precision molding.

In Comparative Example A, when the LiF content is higher than 0.45%, the R _OH (S) value increases sharply, the leaching quality increases, the stability of alkali resistance becomes worse, and the chemical stability of the glass becomes worse, T _g /L _t The smaller the value, the worse the crystallization performance of the glass. At the same time, the degree of abrasion F _A also increases, which is not conducive to the tolerance control in the process of fine grinding and polishing of glass.

In comparative example B, the content of BaF ₂ is lower than 7.5%, so that the ratio of BaF ₂ /(CaF ₂ +MgF ₂ ) is lower than 0.3, the alkali resistance D _A is grade 5, and the leaching quality of D _A is greatly increased, which shows that the chemical properties of glass The stability deteriorates seriously, and the T _g /Lt value decreases, indicating that the crystallization performance of the glass deteriorates, which is not conducive to the forming of the glass, and at the same time, the abrasion degree also deteriorates.

In comparative example C, the ratio of Al(PO ₃ ) ₃ /LiF is too low, other compositions are all within the limits of the present invention, nd, vd, alkali resistance, abrasion, and specific gravity are all in line with the limits of the present invention, but due to Al When the ratio of (PO ₃ ) ₃ /LiF is lower than 13, the crystallization performance becomes worse.

It can be seen from Table 5 that the preparation methods of Comparative Examples D and E are different from those of Example 1, wherein the hydroxyl content in the glass is relatively high, and the transmittance in the 3000nm band is low, resulting in poor alkali resistance. The preparation method of Example 1 The prepared glass has less hydroxyl group content, high transmittance in the 3000nm band, and improved alkali resistance.

It should be noted that although the technical solutions of the present invention are described with specific examples, those skilled in the art can understand that the present invention should not be limited thereto.

Having described various embodiments of the present invention, the foregoing description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and alterations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principle of each embodiment, practical application or technical improvement in the market, or to enable other ordinary skilled in the art to understand each embodiment disclosed herein.

Claims (10)

1. A fluorophosphate optical glass, characterized in that it comprises the following components in terms of compounds: Al(PO ₃ ) ₃ : 5% to 12%, preferably 6% to 10%; AlF ₃ : 22% to 33%, preferably 23% to 30%; BaF ₂ : 7.5% to 15%, preferably 9% to 13%; SrF ₂ : 20% to 30%, preferably 22% to 29%; CaF ₂ : 20% to 30%, preferably 22% to 28%; MgF ₂ : 2% to 7%, preferably 2% to 5%; YF ₃ : 0.5% to 8%, preferably 0.5% to 6%; LiF: 0.05% to 0.45%, preferably 0.1% to 0.35%; The above percentages are all percentages by mass; The refractive index n _d of the fluorophosphate optical glass is 1.43-1.46, and the Abbe number υ _d is 90-100. 2. The fluorophosphate optical glass according to claim 1, characterized in that, in terms of weight percent, the ratio BaF ₂ /CaF ₂ between the content of BaF ₂ and the content of CaF ₂ is 0.35-0.72, preferably 0.36-0.64; and / or, The ratio BaF ₂ /(MgF ₂ +CaF ₂ ) of the content of BaF ₂ to the sum of the contents of MgF ₂ and CaF ₂ is 0.3-0.64, preferably 0.32-0.56; and/or, The ratio Al(PO ₃ ) ₃ /LiF of the content of Al(PO ₃ ) ₃ to the content of LiF is 13-180, preferably 13-150. 3. The optical glass according to claim 1 or 2, characterized in that the composition of the fluorophosphate optical glass does not contain P ₂ O ₅ , NaF, KF, SnF ₄ , La ₂ O ₃ , Gd ₂ O _3. At least one of Y ₂ O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , GeO ₂ , CaO, BaO, SrO and MgO. 4. The fluorophosphate optical glass according to any one of claims 1-3, characterized in that the crystallization upper limit temperature L _t of the fluorophosphate optical glass is below 680° C., and the glass transition temperature T _g is 440° C. below °C; and/or, The devitrification resistance T _g /L _t of the fluorophosphate optical glass is greater than 0.64. 5. according to the described fluorophosphate optical glass of any one of claim 1-4, it is characterized in that, λ ₈₀ in the coloring degree λ ₈₀ /λ ₅ of described fluorophosphate optical glass is below 310nm, and λ ₅ is Below 190nm. 6. The fluorophosphate optical glass according to any one of claims 1-5, characterized in that, the specific gravity of the fluorophosphate optical glass is 3.80 g/cm ³ or less. 7. The fluorophosphate optical glass according to any one of claims 1-6, characterized in that, the alkali resistance R _OH (S) of the fluorophosphate optical glass is 4 grades and above; and/or The abrasion degree F _A of the fluorophosphate optical glass is 455 or less. 8. A method for preparing the fluorophosphate optical glass according to any one of claims 1-7, characterized in that it comprises: weighing each component according to the proportion, mixing them uniformly and then melting them, and During the smelting process, the volatile gas is fully released; preferably, the temperature of the smelting is 800-900° C.; and then poured or leaked into a molding mold, or directly pressed into shape. 9. The preparation method according to claim 8, characterized in that, after the smelting, it also includes, in a closed environment, raising the temperature to 900-1000°C and turning on the stirrer for stirring, and the stirring time is controlled at 3 ~8h; After the stirring is completed, raise the temperature to 1000~1050°C and keep it warm for 4~9h to clarify and make the bubbles fully float up, and then lower the temperature to 600~700°C. 10. An optical element, comprising the fluorophosphate optical glass according to any one of claims 1-7.