CN110964435A

CN110964435A - Fluorescent polymer, white light LED prepared from fluorescent polymer and preparation method of white light LED

Info

Publication number: CN110964435A
Application number: CN201811149104.3A
Authority: CN
Inventors: 乔金樑; 胡晨曦; 张晓红; 茹越; 郭照琰; 赖金梅; 蔡传伦; 戚桂村; 高建明; 李秉海; 王湘; 宋志海; 蒋海斌; 韩朋; 张红彬
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2018-09-29
Filing date: 2018-09-29
Publication date: 2020-04-07
Anticipated expiration: 2038-09-29
Also published as: CN110964435B

Abstract

The invention relates to a fluorescent polymer, a preparation method thereof and a white light LED prepared from the fluorescent polymer, belonging to the technical field of semiconductor luminescence. The fluorescent polymer is obtained by adding a maleic anhydride copolymer into an aqueous solution of water-soluble hydroxide for sufficient reaction. The fluorescent polymer emits fluorescence that is one of the following: blue light with the strongest emission range of 450-520 nm, red light with the strongest emission range of 575-670 nm or yellow light with the strongest emission range of 530-570 nm. The white light LED comprises an excitation chip and a light emitting layer; the light-emitting layer comprises a fluorescent polymer and a matrix material; the white light LED has a mature packaging process, the raw materials of the fluorescent polymer with high fluorescence intensity and the articles used in the process are low in price and rich in resources, the preparation method is simple and low in environmental pollution, and the white light LED has a wide color temperature coverage range and can meet application requirements under different conditions, so that the white light LED has a wide application prospect.

Description

Fluorescent polymer, white light LED prepared from fluorescent polymer and preparation method of white light LED

Technical Field

The invention relates to the technical field of semiconductor light emitting, in particular to a fluorescent polymer, a white light LED prepared from the fluorescent polymer and a preparation method of the white light LED.

Background

White light emitting diodes (white LEDs) are known as new light sources in the 21 st century, being a fourth generation of light sources following incandescent, fluorescent, high intensity gas discharge lamps. The energy-saving energy-.

At present, there are mainly 3 ways to realize white light by using LED technology: (1) the near ultraviolet LED chip is used for exciting red, green and blue three-primary-color fluorescent powder to obtain white light; (2) the red light chip, the green light chip and the blue light chip are assembled to realize white light; (3) the blue light chip is used for exciting the yellow fluorescent powder, and the yellow light emitted by the fluorescent powder is compounded with the residual blue light to realize white light. In the first method, the wavelength difference between near ultraviolet light and red, green and blue light is large, so that energy waste is caused, and the method is not in accordance with the current environment-friendly and energy-saving target; in the second method, white light LEDs with various color temperatures can be designed by controlling the proportion of the three chips, but the preparation and assembly processes are complex; the third method is the most widely applied form in the current market, the yellow fluorescent powder is mostly YAG Ce with an yttrium aluminum garnet structure, the process is mature, but the YAG Ce is a non-renewable rare earth resource, and the development of renewable and low-cost fluorescent powder has very important significance.

In recent years, fluorescent Materials with high quantum yield are widely researched by researchers, and Miao et al (MiaoX, Qu D, Yang D, et al. Photolutenescence: Synthesis of Carbon Dots with multiple color Emission by control of hydrothermal reaction and Surface catalysis [ J ]. Advanced Materials,2017,30(1):1870002.) prepare blue, green and red Carbon Dots by controlling the ratio of the three Carbon Dots, but the high-temperature and high-pressure environment required by the hydrothermal reaction can increase energy consumption, and the yield is low, thereby being incapable of realizing industrial mass production. The fluorescent polymer can be produced in large scale, but as mentioned above, most of the fluorescent polymers capable of emitting yellow-red light in the current publications and patents have conjugated groups such as benzene rings, and the conjugated groups have potential biological toxicity. Non-traditional fluorescent polymers (i.e. containing no conjugated structures such as benzene rings) such as sodium alginate, polyvinylpyrrolidone, hyperbranched polyester, polyacrylonitrile and the like can only emit blue-green light, and the preparation and modification steps of a very few non-traditional fluorescent polymers capable of emitting yellow-red light are relatively complex, and a patent 201711042409.X discloses a high-intensity non-conjugated fluorescent polymer, but only can emit blue fluorescence; the patent 201711034920.5 discloses a red non-conjugated fluorescent polymer, but it has low fluorescence intensity and needs heat treatment to convert it into red polymer, so that the cost and operation steps are increased, therefore, the preparation of non-traditional fluorescent polymer with long wavelength (more than 500nm) fluorescence emission has high research value.

At present, the technical process of generating white light by exciting the combination of fluorescent powder by adopting purple light or blue light is relatively mature, but the application of the non-traditional fluorescent polymer with high quantum yield and low preparation cost in the aspect of white light LEDs is not reported, so that the non-traditional fluorescent polymer with no pollution, high fluorescence intensity and low preparation cost replaces nonrenewable rare earth fluorescent powder by utilizing the existing device technology, and further the realization of the white light LEDs has extremely important market value and economic significance.

Disclosure of Invention

The invention provides a non-conjugated fluorescent polymer with high fluorescence intensity, in particular to a fluorescent polymer, a white light LED prepared from the fluorescent polymer and a preparation method of the fluorescent polymer. The novel non-conjugated fluorescent polymer with high fluorescence intensity provided by the invention has the advantages of low price of raw materials and reagents in the process, mature production process and low environmental pollution. The preparation method of the fluorescent polymer is simple and easy to implement, has various application forms, and is extremely easy to industrially popularize.

The white light LED provided by the invention has the advantages of mature packaging process, low price and abundant resources of raw materials of the fluorescent polymer with high fluorescence intensity and articles used in the process, simple preparation method and low environmental pollution, and the white light LED has wide color temperature coverage range, thereby having wide application prospect.

It is an object of the present invention to provide a fluorescent polymer. The fluorescent polymer emits fluorescence that is one of the following: blue light with the strongest emission range of 450-520 nm, red light with the strongest emission range of 575-670 nm or yellow light with the strongest emission range of 530-570 nm.

The fluorescent polymer is a polymer having the following general formula (I):

wherein x, y and z are natural numbers, x is more than or equal to 1, and y + z is more than or equal to 0;

the group R₁、R₂、R₄、R₅Is at least one of metal ions, preferably at least one of monobasic alkali metal ions; r₁、R₂、R₄、R₅May be the same or different;

the group R₃、R₆Can be selected from at least one of hydroxyl and ester group, preferably hydroxyl and CH₃COO-、CH₃CH₂COO-、CH₃CH₂CH₂COO-or a salt thereof.

In the general formula (I), preferably at least one of y and z is 0; more preferably, y is 0.

The fluorescent polymer is characterized in that the fluorescent polymer is obtained by adding a maleic anhydride copolymer into an aqueous solution of metal hydroxide and fully reacting.

The invention also aims to provide a preparation method of the fluorescent polymer. The preparation method does not use organic solvent, and the fluorescent polymer can be obtained by directly adding the maleic anhydride copolymer solid into the water solution of the water-soluble hydroxide for sufficient reaction. Specifically, the preparation method of the fluorescent polymer may include the steps of:

a. adding water-soluble metal hydroxide into water for dissolving to obtain a metal hydroxide aqueous solution;

b. and c, adding a maleic anhydride copolymer into the aqueous solution of the metal hydroxide prepared in the step a, fully mixing, and removing the solvent to obtain the fluorescent polymer solid.

Wherein the content of the first and second substances,

in step a, the water-soluble metal hydroxide may be at least one selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and francium hydroxide, preferably at least one selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide and rubidium hydroxide.

In the step a, the weight ratio of the water-soluble metal hydroxide to the water can be (0.1-100): 100, preferably (0.1 to 50): 100, more preferably (1 to 50): 100.

in step b, the maleic anhydride copolymer can be selected from the maleic anhydride copolymers existing in the prior art, and is preferably selected from polymaleic anhydride-vinyl ester copolymers. More preferably at least one of maleic anhydride-vinyl formate copolymer, maleic anhydride-vinyl acetate copolymer, maleic anhydride-vinyl propionate copolymer, and maleic anhydride-vinyl butyrate copolymer, and more preferably maleic anhydride-vinyl acetate copolymer.

Generally, the maleic anhydride copolymer may have a linear structure or a crosslinked structure, such as a crosslinked structure obtained by adding a crosslinking agent thereto. The maleic anhydride copolymer can be prepared by a method known in the art. Preferably, they can be prepared by the methods proposed in CN1618826A (Chinese patent ZL200310115329.4) and CN101338007A (Chinese patent application 200810118553.1).

When a solid of the maleic anhydride copolymer is added, molecular chains of the maleic anhydride copolymer are in an entangled state, and due to the presence of metal hydroxide in a solution, the maleic anhydride in the maleic anhydride copolymer and the metal hydroxide can generate a ring-opening reaction to generate carboxylate; meanwhile, ester groups in the maleic anhydride copolymer can be hydrolyzed to generate hydroxyl in a certain amount under an alkaline condition, and the generated hydroxyl can be subjected to esterification reaction with the original maleic anhydride under an alkaline catalysis condition, so that intramolecular and intermolecular crosslinking reaction can be generated. The entanglement of polymer molecular chains and the interaction between original and newly generated secondary fluorescent groups (such as C-O, C-O) can cause cluster aggregation of the secondary fluorescent groups, lone pair electrons and pi electrons in the aggregates are overlapped to generate space conjugation, and blue, yellow and red fluorescent polymers with high fluorescence intensity can be formed due to different aggregation states formed by the reaction between maleic anhydride copolymers and metal hydroxides in different proportions. The weight ratio of the maleic anhydride copolymer to the water-soluble metal hydroxide contained in the metal hydroxide aqueous solution can be (0.1-10): 1; as the specific gravity of the maleic anhydride copolymer and the metal hydroxide is increased, the fluorescence of the obtained fluorescent polymer is transited from red light to yellow light to blue light. Wherein the weight ratio of the maleic anhydride copolymer to the water-soluble metal hydroxide contained in the metal hydroxide aqueous solution is preferably (4-10): 1, more preferably (5 to 8): 1, obtaining a blue light fluorescent polymer with the strongest emission range of 450-520 nm; when the weight ratio is preferably (2-3.8): 1, more preferably (2.5 to 3.5): 1, obtaining the yellow fluorescent polymer with the strongest emission range of 530-570 nm; when the weight ratio is preferably (0.1-1.8): 1, more preferably (0.1 to 1):1, obtaining the red light fluorescent polymer with the strongest emission range of 575-670 nm.

A certain reaction time is required since the maleic anhydride copolymer reacts with the metal hydroxide to form a uniform solution. In principle, the reaction of the maleic anhydride copolymer in the aqueous metal hydroxide solution to form a clear solution can be stopped, and the reaction time is preferably 0.05 to 24 hours, more preferably 0.1 to 12 hours, and most preferably 0.1 to 6 hours. The reaction temperature and the reaction pressure in this step are not particularly limited, and the temperature is only between the boiling point and the freezing point of water, the reaction temperature is preferably 0-100 ℃, more preferably room temperature, and the reaction pressure is preferably normal pressure; the apparatus used for the reaction is also not particularly limited, and the apparatus known in the art for solution reaction can be used. The stirring is also unlimited, and can be fast or slow or not; the solvent used for the prepared fluorescent polymer is drying, the drying temperature and time are not particularly limited according to the equivalence of time and temperature, and water is removed, and the drying method can be various drying methods in the prior art, including freeze drying, spray drying and the like.

The invention also provides a white light LED.

The white light LED comprises an excitation chip and a light emitting layer; the luminescent layer comprises at least one of the fluorescent polymers and a matrix material;

the light-emitting layer is arranged on the surface of the excitation chip, the thickness of the light-emitting layer can be adjusted according to actual needs, and specifically, the thickness range of the light-emitting layer is 0.01 cm-10 cm, and preferably 0.01 cm-5 cm.

The weight ratio of the fluorescent polymer to the base material can be (0.01-100) to 1, preferably (0.1-100): 1, more preferably (0.1 to 50): 1, most preferably (0.1 to 25): 1. the fluorescent polymer is selected from at least one of the following fluorescent polymers of the present invention: blue light fluorescent polymer, yellow light fluorescent polymer, red light fluorescent polymer; the yellow fluorescent polymer, the red fluorescent polymer alone or a mixture of yellow-red fluorescent polymers, a mixture of blue-red fluorescent polymers, and a mixture of blue-yellow-red fluorescent polymers are preferable.

The yellow fluorescent polymer and the red fluorescent polymer can well emit white light under the excitation of a chip when used independently, so that the yellow fluorescent polymer and the red fluorescent polymer in the mixture of the yellow and red fluorescent polymers are mixed and used in any proportion;

in the mixture of the blue-red fluorescent polymers, the weight ratio of the blue-red fluorescent polymers to the blue-red fluorescent polymers is 1: (0.1 to 100), preferably 1: (1-100);

in the mixture of the blue-yellow-red fluorescent polymers, the weight ratio of the blue-yellow fluorescent polymer to the red-red fluorescent polymer is 1: (0.1-100): (0.1 to 100), preferably 1: (1-100): (1-100).

The excitation chip can be selected from ultraviolet or blue light chips existing in the prior art and commercialization, and the maximum emission peak range of the excitation chip is 365 nm-480 nm, preferably 365 nm-460 nm.

The matrix material can be selected from at least one of phenolic resin, urea resin, epoxy resin, unsaturated polyester, polyisocyanate, acrylic acid diester, organic silicon resin, polyimide, polyurethane resin, polysulfide rubber, silicon rubber, paraffin, organic glass, polyethylene, ethylene-vinyl acetate copolymer and polycarbonate, and preferably at least one of epoxy resin, organic silicon resin, polyurethane resin, silicon rubber, organic glass and ethylene-vinyl acetate copolymer. Processing aids commonly used in the art, such as curing agents, antioxidants, and the like, can be added in conventional amounts depending on the material characteristics of the respective substrate. The substrate used in the present invention may be in a liquid state or a solid state, and preferably in a liquid state. When the matrix material is in a solid state, the fluorescent polymer can be mixed with the matrix material by a common melt blending method and then used; the technological conditions and parameters of melt blending adopt the respective existing technological conditions and parameters of melt blending of the base materials.

The fourth purpose of the invention is to provide a preparation method of the white light LED, which comprises the following steps:

and uniformly mixing the components including the fluorescent polymer and the matrix material according to the using amount to form a light-emitting layer, and placing the light-emitting layer on the surface of the excitation chip.

The mixing manner of the fluorescent polymer and the matrix material is not particularly limited, and may be various mixing methods in the prior art, including stirring and mixing, ultrasonic mixing, melt blending, and the like;

the light emitting layer formed by uniformly mixing the fluorescent polymer and the matrix material is arranged on the surface of the excitation chip, the method comprises the steps of coating the mixture of the fluorescent polymer and the liquid matrix material on the surface of the excitation chip, and obtaining the white light LED after the matrix material is cured; or adhering the solidified luminescent layer containing the fluorescent polymer and the matrix material to the surface of the excitation chip; or the luminescent layer which is formed by melting, blending, cooling and molding the fluorescent polymer and the matrix material is attached to the surface of the excitation chip.

The curing temperature and time of the matrix materials are determined according to the respective existing curing conditions of the matrix materials; the temperature and time for melt blending the matrix material are determined according to the existing technical conditions of the matrix material.

The attaching may include merely placing (attaching) the laser chip on the surface, and may also include attaching the laser chip to the surface by using a general-purpose adhesive.

The inventor of the application discovers in research that the maleic anhydride copolymer is subjected to the modification treatment of the invention, so that a fluorescent polymer with high fluorescence intensity and fluorescence emission covering one of blue light, yellow light and red light can be obtained, and the fluorescent polymer is further mixed with a base material and packaged on the surface of an ultraviolet or blue light LED chip, so that a white light LED covering warm white light (3000-3500K), neutral white light (3500-5500K) and cool white light (5500-7500K) regions can be obtained. The encapsulation refers to placing (covering) a mixture of the fluorescent polymer and the matrix material on the surface of the chip.

The main advantages of the invention are:

① the maleic anhydride copolymer is a by-product of industrial polyolefin synthesis, the raw materials are easy to obtain, and the industrial production process is mature;

② the preparation method of the fluorescent polymer with high fluorescence intensity is simple and easy to operate, organic solvent is not used, the materials involved in the preparation method are all materials with abundant storage, and the involved devices are all common devices in industrial production;

③ the packaging process used in the present invention can be carried out using current commercial technology without the need to redesign the device;

④ the color temperature of the white light LED of the invention can cover warm white light region, neutral white light region and cold white light region, can meet the application requirements under different conditions, and has low production cost, mature production process and easy realization of industrial production.

Drawings

FIG. 1 is a three-dimensional spectrum of a fluorescent polymer solid prepared in example 1;

FIG. 2 is an elemental energy spectrum of a fluorescent polymer solid prepared in example 1;

FIG. 3 is a three-dimensional spectrum of a fluorescent polymer solid prepared in example 2;

FIG. 4 is a three-dimensional spectrum of a fluorescent polymer solid prepared in example 3;

FIG. 5 is a Fourier infrared spectrum of the fluorescent polymers prepared in examples 1 to 3;

FIG. 6 shows emission spectra of white LEDs prepared in examples 4 to 8 and a comparative example.

Detailed Description

The present invention will be further described with reference to the following examples. However, the present invention is not limited to these examples. The experimental data in the examples were determined using the following instruments and methods:

(1) and (3) observation of fluorescence phenomenon: the samples of examples and comparative examples were placed in a dark room and the fluorescence phenomenon was observed under UV irradiation with a UV lamp power of 24W and UV wavelength of 365 nm.

(2) The fluorescence spectrum data and the absolute quantum yield are analyzed and tested by adopting a JY FL3 fluorescence spectrometer of the Japan Horiba company, a 450W xenon lamp light source is adopted, the excitation wavelength range is 250-650 nm, and the emission spectrum range is 300-1000 nm.

(3) The LED emission spectrum, CIE 1931 coordinates, color temperature and color rendering index were all analyzed and tested using an IQL919 spectrophotometer, available from Image Quality Labs.

The maleic anhydride-vinyl acetate linear alternating copolymer (MVL) used in the examples was prepared by referring to example 4 of Chinese patent publication No. CN1618826A, and the main preparation conditions and parameters were as follows: the molar ratio of the reaction monomer maleic anhydride to vinyl acetate is 1:1, the medium is butyl acetate, the initiator is dibenzoyl peroxide, the reaction is carried out for 5 hours at the temperature of 80 ℃, and the average particle size of the microspheres is 440 nm.

The maleic anhydride-vinyl acetate crosslinked copolymer (MVC) used in the examples was prepared by referring to example 1 of Chinese patent publication No. CN101338007A, and the main preparation conditions and parameters were as follows: the molar ratio of the reaction monomers maleic anhydride and vinyl acetate is 1:1, taking butyl acetate as a medium, dibenzoyl peroxide as an initiator, diethylene glycol dimethacrylate (EGDMA) as a crosslinking agent, reacting for 4 hours at 80 ℃, and obtaining the microsphere with the average particle size of 460 nm.

Other raw materials, ultraviolet and blue light excitation LED chips (Shenzhen Shenwanglong science and technology Limited, power: 1W) are all commercially available.

Preparation of fluorescent polymers

Example 1

Weighing 1g of sodium hydroxide and dissolving in 20g of water; weighing 2g of MVL, putting into a sodium hydroxide aqueous solution, and stirring; after MVL is completely dissolved, the solution is treated at 50 ℃ for 12 hours and then dried to obtain the yellow fluorescent polymer with high fluorescence intensity, the absolute quantum yield of the yellow fluorescent polymer is 31 percent, the three-dimensional fluorescence spectrum of the yellow fluorescent polymer is shown in figure 1, and when the excitation range is 330nm to 560nm, the strongest emission range is 530nm to 570 nm. The Fourier infrared spectrum of the fluorescent polymer is shown in FIG. 5-1, wherein 3500, 2972, 1725, 1583, 1414, 1260 and 1035cm^-1Are respectively-OH, -CH, C-O, COO^-Ion, -CH₃And C-O-C, C-O group. COO (carbon organic compound)^-By ionic is meant that the starting material reacts with a water-soluble hydroxide to form a carboxylate, such as sodium carboxylate in this example: -COO^-Na⁺In the infrared spectrogram, only COO appears^-The presence of metal ions is indicated by the characteristic peaks of (A). The energy spectrum of the fluorescent polymer is shown in FIG. 2, and the existence of sodium element also proves that sodium ions exist in the reaction product.

Example 2

Weighing 1g of lithium hydroxide and dissolving in 2g of water; weighing 0.2g of MVL, putting into a lithium hydroxide aqueous solution, and stirring; waiting MVAnd after L is completely dissolved, treating the solution at 50 ℃ for 12 hours, and drying to obtain the red light fluorescent polymer with high fluorescence intensity, wherein the absolute quantum yield of the red light fluorescent polymer is 12%, the three-dimensional fluorescence spectrum of the red light fluorescent polymer is shown in figure 3, and when the excitation range is 300-600 nm, the strongest emission range is 575-670 nm. The Fourier infrared spectrum of the fluorescent polymer is shown in FIG. 5-2, wherein 3500, 2972, 1725, 1583, 1414, 1260 and 1035cm^-1Are respectively-OH, -CH, C-O, COO^-Ion, -CH₃And C-O-C, C-O group.

Example 3

Weighing 1g of potassium hydroxide and dissolving in 2g of water; weighing 5g of MVC, putting into the potassium hydroxide aqueous solution, and stirring; after MVC is completely dissolved, the solution is treated at 50 ℃ for 12 hours and then dried to obtain the blue light fluorescent polymer with high fluorescence intensity, the absolute quantum yield of the blue light fluorescent polymer is 14%, the three-dimensional fluorescence spectrum of the blue light fluorescent polymer is shown in figure 4, and when the excitation range is 300nm to 450nm, the strongest emission range is 450nm to 520 nm. The Fourier infrared spectrum of the fluorescent polymer is shown in FIG. 5-3, wherein 3500, 2972, 1725, 1583, 1414, 1260 and 1035cm^-1Are respectively-OH, -CH, C-O, COO^-Ion, -CH₃And C-O-C, C-O group.

White light LED

Example 4

20g of the fluorescent polymer prepared in example 1 and 1g of polydimethylsiloxane (Dow Corning 184, wherein the weight ratio of the polydimethylsiloxane to the curing agent is 10:1) are weighed and uniformly mixed to obtain a mixed solution, then the mixed solution is coated on the surface of an LED chip with the maximum emission wavelength of 460nm, and a white light LED is obtained after curing is carried out for 1 hour at 80 ℃, wherein the thickness of a fluorescent layer of the white light LED is 0.01 cm. The fluorescence emission spectrum of the prepared white light LED is shown in figure 6-1, the CIE 1931 coordinate is (0.33,0.34), the color temperature is 5436K, the color rendering index is 75.1, and the white light LED belongs to a neutral white light region.

Comparative example 1

1g of polydimethylsiloxane (same as example 4) was weighed out and coated on the surface of an LED chip with a maximum emission wavelength of 460nm, and the fluorescence emission spectrum of the prepared LED was measured after the polydimethylsiloxane was cured at 80 ℃ for 1 hour, as shown in FIG. 6-2, with CIE 1931 coordinates (0.14,0.06) corresponding to 460nm LED chips.

Comparative example 2

20g of commercial rare earth phosphor (yttrium aluminum garnet, abbreviated as YAG: Ce, with a maximum emission peak of 558nm) was weighed and mixed uniformly with 1g of polydimethylsiloxane (same as example 4), and then packaged on the surface of an LED chip with a maximum emission wavelength of 460nm, and cured at 80 ℃ for 1 hour to obtain a white light LED, wherein the thickness of the phosphor layer is 0.01 cm. The fluorescence emission spectrum of the prepared white light LED is shown in FIGS. 6-3, the CIE 1931 coordinate is (0.36,0.38), the color temperature is 4601K, and the color rendering index is 71.9, and the white light LED belongs to a neutral white light region. Example 4 compared with this comparative example, the fluorescence spectrum of the white LED prepared by the method is very similar, the color rendering index is larger than that of comparative example 2 (the upper limit of the definition of the color rendering index is 100, and the larger the white LED is, the better the white LED is), while the cost of the fluorescent material used in example 4 is far lower than that of the rare earth fluorescent powder, which also shows that the fluorescent polymer of the invention has the possibility of greatly replacing the rare earth fluorescent powder.

Example 5

1g of the fluorescent polymer prepared in example 1 and 10g of polydimethylsiloxane (same as in example 4) are weighed and uniformly mixed, then the mixture is coated on the surface of an LED chip with the maximum emission wavelength of 460nm, and the white light LED is obtained after curing for 1 hour at 80 ℃, wherein the thickness of a fluorescent layer of the white light LED is 5 cm. The prepared white light LED fluorescence emission spectrogram is shown in FIGS. 6-4, the CIE 1931 coordinate is (0.31,0.30), the color temperature is 7216K, and the color rendering index is 75.1, and the white light LED fluorescence emission spectrogram belongs to a cold white light region.

Example 6

1g of the fluorescent polymer prepared in example 2 and 1g of polydimethylsiloxane (same as in example 4) are weighed and uniformly mixed, then the mixture is coated on the surface of an LED chip with the maximum emission wavelength of 395nm, and the white light LED is obtained after curing for 1 hour at 80 ℃, wherein the thickness of a fluorescent layer of the white light LED is 1 cm. The fluorescence emission spectrum of the prepared white light LED is shown in FIGS. 6-5, the CIE 1931 coordinate thereof is (0.45,0.46), the color temperature is 3136K, and the color rendering index is 86.2, and the white light LED belongs to a warm white light region.

Example 7

3g of the fluorescent polymer prepared in example 2 and 2g of the fluorescent polymer prepared in example 3 were weighed, mixed uniformly with 1g of epoxy resin (containing curing agent) (liquid epoxy resin prepolymer, chinese petrochemical, EP CYD-128; curing agent: triethanolamine, epoxy resin and curing agent weight ratio 1:0.3), coated on the surface of an LED chip with a maximum emission wavelength of 365nm, and cured at room temperature for 6 hours to obtain a white LED with a fluorescent layer having a thickness of 0.5 cm. The fluorescence emission spectrum of the prepared white light LED is shown in FIGS. 6-6, the CIE 1931 coordinate is (0.39,0.37), the color temperature is 3709K, and the color rendering index is 75.2, and the white light LED belongs to a neutral white light region.

Example 8

Weighing 1g of the fluorescent polymer prepared in example 1, 1g of the fluorescent polymer prepared in example 2, 1g of the fluorescent polymer prepared in example 3 and 10g of ethylene-vinyl acetate copolymer (Yanshan petrochemical), uniformly mixing, then carrying out melting and hot-press molding at 150 ℃, cooling, and attaching to the surface of an LED chip with the maximum emission wavelength of 365nm to obtain the white LED, wherein the thickness of the fluorescent layer is 1 cm. The fluorescence emission spectrum of the prepared white light LED is shown as 6-7, the CIE 1931 coordinate is (0.35,0.36), the color temperature is 4849K, and the color rendering index is 87.3, and the white light LED belongs to a neutral white light region.

Claims

1. A fluorescent polymer, which is a polymer having the following general formula (I):

the group R₁、R₂、R₄、R₅Is at least one of metal ions, preferably at least one of monobasic alkali metal ions;

the group R₃、R₆At least one selected from hydroxyl and ester group, preferably hydroxyl and CH₃COO-、CH₃CH₂COO-、CH₃CH₂CH₂COO-or a salt thereof.

2. The fluorescent polymer of claim 1, wherein:

in the general formula (I), at least one of y and z is 0; preferably, y-z-0.

3. The fluorescent polymer of claim 1, wherein:

the fluorescent polymer emits fluorescence that is one of the following: blue light with the strongest emission range of 450-520 nm, red light with the strongest emission range of 575-670 nm or yellow light with the strongest emission range of 530-570 nm.

4. A fluorescent polymer according to any one of claims 1 to 3, which is obtained by adding a maleic anhydride copolymer to an aqueous solution of a metal hydroxide and reacting the mixture sufficiently.

5. A method of preparing a fluorescent polymer according to any of claims 1 to 4, characterized in that it comprises the steps of:

a. adding water-soluble metal hydroxide into water for dissolving to obtain a metal hydroxide aqueous solution; wherein the weight ratio of the water-soluble metal hydroxide to water is (0.1-100): 100, preferably (0.1 to 50): 100, respectively;

b. adding a maleic anhydride copolymer into the aqueous solution of the metal hydroxide prepared in the process a, and removing the solvent after fully mixing to obtain the fluorescent polymer; wherein the weight ratio of the maleic anhydride copolymer to the water-soluble metal hydroxide is (0.1-10): 1.

6. the method of claim 5, wherein:

in step a, the water-soluble metal hydroxide is selected from at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and francium hydroxide, preferably at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide and rubidium hydroxide.

7. The method of claim 5, wherein:

in the step b, the weight ratio of the maleic anhydride copolymer to the water-soluble metal hydroxide is (4-10): 1, preferably (5-8): 1, obtaining a blue light fluorescent polymer with the strongest emission range of 450-520 nm; when the weight ratio is (2-3.8): 1, preferably (2.5-3.5): 1, obtaining the yellow fluorescent polymer with the strongest emission range of 530-570 nm; when the weight ratio is (0.1-1.8): 1, preferably (0.1 to 1):1, obtaining the red light fluorescent polymer with the strongest emission range of 575-670 nm.

8. The method of claim 5, wherein:

in the step b, the maleic anhydride copolymer is selected from at least one of maleic anhydride-vinyl ester copolymer, preferably maleic anhydride-vinyl formate copolymer, maleic anhydride-vinyl acetate copolymer, maleic anhydride-vinyl propionate copolymer and maleic anhydride-vinyl butyrate copolymer, and more preferably maleic anhydride-vinyl acetate copolymer.

9. A white light LED comprises an excitation chip and a light emitting layer; the light-emitting layer comprises at least one of the fluorescent polymers according to any one of claims 1 to 4 or at least one of the fluorescent polymers prepared by the preparation method according to any one of claims 5 to 8 and a matrix material; the weight ratio of the fluorescent polymer to the base material is (0.01-100): 1, preferably (0.1-100): 1;

the light-emitting layer is arranged on the surface of the excitation chip, and the thickness range of the light-emitting layer is 0.01 cm-10 cm, preferably 0.01 cm-5 cm.

10. The white LED of claim 9, wherein:

the fluorescent polymer is selected from at least one of the following polymers: blue light fluorescent polymer, yellow light fluorescent polymer, red light fluorescent polymer; yellow fluorescent polymers, red fluorescent polymers, mixtures of yellow-red fluorescent polymers, mixtures of blue-red fluorescent polymers or mixtures of blue-yellow-red fluorescent polymers are preferred.

11. The white LED of claim 10, wherein:

the weight ratio range of the blue light fluorescent polymer to the red light fluorescent polymer in the blue-red fluorescent polymer mixture is 1: (0.1 to 100), preferably 1: (1-100);

the weight ratio range of the blue light fluorescent polymer, the yellow light fluorescent polymer and the red light fluorescent polymer in the blue-yellow-red fluorescent polymer mixture is 1: (0.1-100): (0.1 to 100), preferably 1: (1-100): (1-100).

12. The white LED of claim 9, wherein:

the maximum emission peak of the excitation chip is in the range of 365 nm-480 nm, preferably 365 nm-460 nm.

13. The white LED of claim 9, wherein:

the matrix material is selected from at least one of phenolic resin, urea resin, epoxy resin, unsaturated polyester, polyisocyanate, acrylic acid diester, organic silicon resin, polyimide, polyurethane resin, polysulfide rubber, silicon rubber, paraffin, organic glass, polyethylene, ethylene-vinyl acetate copolymer and polycarbonate, and preferably at least one of epoxy resin, organic silicon resin, polyurethane resin, silicon rubber, organic glass and ethylene-vinyl acetate copolymer.

14. The method for preparing a white light LED according to any one of claims 9 to 13, comprising the steps of:

15. The method for preparing a white light LED according to any one of claims 9 to 13, wherein the luminescent layer is disposed on the surface of an excitation chip, and comprises coating the mixture of the fluorescent polymer and the liquid matrix material on the surface of the excitation chip, and curing the matrix material to obtain the white light LED; or adhering the solidified luminescent layer containing the fluorescent polymer and the matrix material to the surface of the excitation chip; or the luminescent layer which is formed by melting, blending, cooling and molding the fluorescent polymer and the matrix material is attached to the surface of the excitation chip.