CN113621126B

CN113621126B - Optical endpoint detection window and preparation method thereof

Info

Publication number: CN113621126B
Application number: CN202010380044.7A
Authority: CN
Inventors: 谢毓; 王凯
Original assignee: Wanhua Chemical Group Electronic Materials Co ltd
Current assignee: Wanhua Chemical Group Electronic Materials Co ltd
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2023-03-24
Anticipated expiration: 2040-05-08
Also published as: CN113621126A

Abstract

The invention discloses an optical endpoint detection window and a preparation method thereof. The optical endpoint detection window is obtained by reacting isocyanate-terminated prepolymer, curing agent and surface-modified nano material as reaction raw materials. The surface modified nano material is isocyanate surface modified nano material. The preparation raw materials of the isocyanate-terminated prepolymer comprise isocyanate, unmodified nano material and polyol, and no other catalyst is used. The optical endpoint detection window can resist photodegradation and hydrolysis and has higher light transmittance.

Description

Optical endpoint detection window and preparation method thereof

Technical Field

The present invention relates to an optical endpoint detection window for a chemical mechanical polishing pad.

Background

During the fabrication of integrated circuits and other electronic devices, it is necessary to deposit or remove multiple layers of conductive, semiconductive, or dielectric materials on or from the surface of a semiconductor wafer. When the material layers are sequentially deposited or removed, the uppermost surface layer of the wafer may become uneven. Because subsequent semiconductor processing (e.g., metal plating) requires the wafer to have a flat surface, the wafer needs to be planarized. Planarization is useful for removing unwanted surface topography and surface defects such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials.

Chemical mechanical planarization or Chemical Mechanical Polishing (CMP) is a common technique used to planarize or polish workpieces, such as semiconductor wafers. One difficulty in chemical mechanical polishing wafers is determining when the substrate is polished to a desired degree. Therefore, in-situ detection of polishing endpoint was developed using laser interferometer using laser generated light to measure substrate dimensions. The in situ optical polishing endpoint detection method can be divided into two basic types: (1) Monitoring optical signals reflected at a single wavelength, or (2) monitoring optical signals reflected from multiple wavelengths. Typically, wavelengths used for optical endpoint detection include the visible spectrum (e.g., 400-700 nm), the ultraviolet spectrum (e.g., 315-400 nm), and the infrared spectrum (e.g., 700-1000 nm). Light from a laser source is transmitted onto the wafer surface and a reflected signal is detected, the reflectance changes as the composition at the wafer surface changes from one metal to another, and the change in reflectance is then used to detect the polishing endpoint.

In order to accurately determine the polishing end point during the use of the polishing pad, the light transmittance of the polishing pad end point detection window is highly required. Chinese patent CN105014527A provides a reactant formula component for an endpoint detection window, which contains an isocyanate terminated prepolymer and a curing agent system, wherein the curing agent system is composed of a bifunctional curing agent and a polyol curing agent. The endpoint detection window exhibits a double pass transmission at 400nm of 25 to 100%. Chinese patent CN105922126A also provides a formulation of a composite material for synthesizing a detection window, which is characterized in that isocyanate for synthesizing a prepolymer is specially selected to meet the requirement of high light transmittance. Chinese patent CN104029115B provides an end-point detection window block made from a cyclic olefin addition polymer, which has the durability required for high demanding polishing applications. Chinese patent CN1744968A proposes a transparent window, which contains at least one inorganic material and at least one organic material. Wherein the inorganic material comprises 20wt% or more of the total weight of the transparent window. Chinese patent CN110627981A proposes an optical resin composition comprising surface-modified inorganic nanoparticles, polyisocyanate and thiol compound, and the obtained optical resin has high transmittance.

Conventional polymer endpoint detection windows suffer from undesirable degradation when exposed to polishing fluids and detection light for extended periods of time, thereby adversely affecting light transmittance and, in turn, optical detection accuracy, thereby affecting polishing quality. There is therefore a need for a photostable polymeric endpoint detection window that has excellent properties of resistance to degradation and high light transmittance when exposed to polishing solutions and light.

Disclosure of Invention

On one hand, the invention provides an optical endpoint detection window which can resist long-time low-wavelength (360-420 nm) light irradiation and reduce photodegradation; even if the polishing solution (most of which is water) is contacted for a long time, the hydrolysis reaction can be reduced; has high light transmittance.

In another aspect, the invention provides a method for preparing an optical endpoint detection window.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

The optical endpoint detection window is obtained by reacting isocyanate-terminated prepolymer, curing agent and surface-modified nano material as reaction raw materials.

The surface modified nano material is isocyanate surface modified nano material. The isocyanate is selected from cycloaliphatic isocyanates containing at least one cyclic structure. Preferably selected from hydrogenated xylylene diisocyanate and/or isophorone diisocyanate.

The nano material is selected from graphene oxide and/or nano zinc oxide.

The size of the nano material is selected from 1-100 nm, preferably 20-80 nm.

The preparation method of the surface modified nano material comprises the following steps: ultrasonically dispersing the nano material in a solvent, adding a catalyst, heating and stirring uniformly at the heating temperature of 50-120 ℃, then adding isocyanate, continuously heating and stirring for 4-15 h, and carrying out suction filtration to obtain the surface modified nano material.

The addition amount of the isocyanate for surface modification of the nano material is 100-500% of the mass of the nano material.

In the preparation method of the surface modified nano material, the solvent for dispersing the nano material is at least one selected from N, N-dimethylformamide, methanol, dimethyl sulfoxide and tetramethyl diethylamine, and is preferably selected from N, N-dimethylformamide and/or dimethyl sulfoxide.

In the preparation method of the surface modification nanometer material, the catalyst is selected from tin compounds, preferably di-n-butyltin dichloride and/or dibutyltin dibutyrate.

In the preparation method of the surface modified nano material, the dosage of the catalyst accounts for 0.5-1.5%, preferably 0.8-1.3% of the mass sum of the isocyanate and the nano material.

The preparation raw materials of the isocyanate-terminated prepolymer comprise isocyanate, unmodified nano materials and polyol, and other catalysts are not used.

In the method for preparing the isocyanate terminated prepolymer, the isocyanate is selected from one or more of dicyclohexylmethane diisocyanate, cyclohexyl diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, cyclohexane dimethylene diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate, 1, 2-propane diisocyanate, 1, 4-butane diisocyanate, 1, 12-dodecane diisocyanate, cyclobutane-1, 3-diisocyanate, cyclohexane-1, 4-diisocyanate and methylcyclohexane diisocyanate, and is preferably selected from one or more of dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate and 1, 4-butane diisocyanate.

In the method for preparing the isocyanate-terminated prepolymer, the polyol is polytetramethylene ether glycol, and the number average molecular weight of the polyol is 300 to 2500, preferably 500 to 2000.

In the isocyanate-terminated prepolymer, the amount of the unmodified nano material accounts for 0.1-3% of the sum of the mass of isocyanate and the mass of polyol.

The surface modified nano material and the unmodified nano material for preparing the isocyanate-terminated prepolymer are the same nano material.

As a preferred technical scheme, the preparation method of the isocyanate-terminated prepolymer comprises the following steps: heating isocyanate to 60-120 ℃, adding the nano material, uniformly mixing, adding the polyol compound, and stirring for reaction for 2-8 hours to obtain the isocyanate-terminated prepolymer.

The isocyanate-terminated prepolymers of the present invention have an unreacted NCO range of 4 to 16 weight percent, preferably 6 to 13 weight percent, based on the sum of the isocyanate and polyol weights.

The curing agent of the invention contains at least one mercapto group, and the curing agent is selected from at least one of pentaerythritol tetramercaptoacetate, pentaerythritol tetramercaptopropionate, trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), bis (mercaptoethyl) sulfide, bis (mercaptomethylthio) methane, bis (2-mercaptoethylthio) methane, bis (3-mercaptopropylthio) methane, 1,2, 3-tris (mercaptomethylthio) propane, and 1,2, 3-tris (2-mercaptoethylthio) propane, and is preferably at least one of pentaerythritol tetramercaptopropionate, trimethylolpropane tris (2-mercaptoacetate), and trimethylolpropane tris (3-mercaptopropionate).

The raw materials for preparing the optical detection window comprise the following components:

50 to 70 parts by mass, preferably 55 to 65 parts by mass, of an isocyanate terminated prepolymer;

30-50 parts by mass of a curing agent, preferably 35-45 parts by mass;

0.1-10 parts by mass of surface-modified nano material, preferably 0.5-5 parts by mass;

wherein the sum of the isocyanate terminated prepolymer and the curing agent is 100 parts by mass.

As a preferred technical solution, the method for preparing an endpoint detection window of the present invention comprises the steps of: firstly, stirring and mixing the surface modified nano material and a curing agent at 50-70 ℃ for 2-3 hours, then adding the mixture into an isocyanate-terminated prepolymer, stirring and defoaming, injecting the obtained combined solution into a mold, heating the mold to 80-130 ℃ for curing for 12-18 hours, and finally cooling to 20-30 ℃ for demolding after 1-3 hours.

The light transmittance of the endpoint detection window is higher than 80% in the full-wave range of visible light.

According to the invention, an unmodified nano material is added into the isocyanate-terminated prepolymer, and the nano material has higher surface energy and surface binding energy due to the nano size, can play the role of a catalyst to a certain extent, but has lower catalytic activity than a common catalyst, so that the isocyanate and the polyol are prevented from undergoing a gel reaction, and the isocyanate-terminated prepolymer is obtained by catalyzing the reaction of the isocyanate and the polyol. The proper increase of the reaction rate shortens the moving time of hard segments and soft segments in the molecule, thereby forming a looser structure and improving the transparency of the prepolymer. The same type of isocyanate surface-modified nano material is added in the synthesis process of the end point detection window, the surface-modified nano material is firstly stirred and mixed with a curing agent containing sulfydryl, so that isocyanate groups on the surface of the surface-modified nano material are pre-reacted with active hydrogen groups in the curing agent, and then are crosslinked with isocyanate-terminated prepolymer, the length of polyurethane molecular chains is increased, the surface-modified nano material and polyurethane molecules form chemical bond combination, and the surface-modified nano material is firmly combined in the polyurethane molecules, so that the polyurethane has better hydrolysis resistance. The nano material has unique light absorption characteristic, so that the nano material also has a beneficial effect on improving the light degradation resistance of the product. Meanwhile, longer molecular chains are curled and wound, and the transparency of the product is further improved. The nano materials are dispersed in polyurethane molecules under the action of chemical bonds and van der Waals force, so that the surface-modified nano materials mutually form a network structure in a polyurethane matrix, and simultaneously, the unmodified nano materials capable of freely moving are doped in the surface-modified nano materials, and the surface-modified nano materials and the unmodified nano materials are mutually cooperated, so that the polyurethane material can be subjected to hydrolysis resistance and photodegradation resistance without reducing the transparency of the polyurethane material.

The end point detecting window glass of the present invention is an insertion type window.

The polishing pad of the present invention has a through opening into which the prepared end-point detection window block is inserted.

The invention provides a chemical mechanical polishing pad having a polishing layer and an end point detection window. The polishing layer is prepared from a thermoplastic polymer. The thermoplastic polymer comprises at least one selected from the group consisting of: polyetherureas, polyisocyanurates, polyurethanes, polyureas, polyurethaneureas, and mixtures thereof.

The invention provides a chemical mechanical polishing pad, the surface of which has a plurality of grooves, the groove design is selected from the following group: concentric grooves (which may be circular or spiral shaped), curved grooves, cross-hatched grooves (e.g., configured as an X-Y grid on the pad surface), other regular designs (e.g., hexagonal, triangular), tread patterns, irregular designs (e.g., fractal patterns), and combinations thereof. Preferably, the trench design is selected from the group of: concentric trenches and/or cross-hatched trenches.

The end point detection window has hydrolysis resistance and photodegradation resistance, and has high light transmittance. The polishing pad has higher optical measurement precision of a grinding end point and better grinding uniformity.

Drawings

FIG. 1 example 1 light transmittance test data before hydrolysis and photodegradation treatment;

FIG. 2 example 2 light transmittance test data before hydrolysis and photodegradation treatment;

FIG. 3 example 3 light transmittance test data before hydrolysis and photodegradation treatment;

FIG. 4 light transmittance test data after hydrolysis and photodegradation treatment in example 1;

FIG. 5 light transmittance test data after hydrolysis and photodegradation treatment in example 2;

FIG. 6 light transmittance test data after hydrolysis and photodegradation treatment in example 3;

FIG. 7 is a graph showing light transmittance test data of comparative example 1 after hydrolysis and photodegradation treatment;

FIG. 8 is a graph showing light transmittance test data of comparative example 2 after hydrolysis and photodegradation treatment;

FIG. 9 is a graph showing light transmittance test data of comparative example 3 after hydrolysis and photodegradation treatment;

FIG. 10 is a graph showing light transmittance test data of comparative example 4 after hydrolysis and photodegradation treatment;

FIG. 11 is a graph showing light transmittance test data of comparative example 5 after hydrolysis and photodegradation treatment;

FIG. 12 is a graph showing light transmittance test data of comparative example 6 after hydrolysis and photodegradation treatment;

FIG. 13 is a graph showing light transmittance test data of comparative example 7 after hydrolysis and photodegradation treatment.

Detailed Description

The method according to the invention will be further illustrated by the following examples, but the invention is not limited to the examples presented, but also encompasses any other known modification within the scope of the claims.

Testing the photo-degradation resistance and hydrolysis resistance:

after the prepared end point detection window is immersed in deionized water for 24 hours, the sizes of the end point detection window in the X and Y directions before and after immersion are measured, and linear size change is recorded.

Providing a light source which can project light with low wavelength (360-420 nm) and continuously irradiate the endpoint detection window soaked in deionized water for 24 hours. The light transmittance of the endpoint detection window was measured according to GBT 2410-2008 using a Hunterlab USVIS1839 colorimeter assay.

Example 1

Preparing a surface modification nano material:

taking 3g of graphene oxide (SIGMA ALDRICH, with the average particle size of 50 nm), ultrasonically dispersing in an N, N-dimethylformamide (Shanghai alatin) solvent, adding 0.05g of di-N-butyltin dichloride (Shanghai Merrel chemical technology Co., ltd.), heating to 80 ℃, uniformly stirring, adding 3.6g of isophorone diisocyanate (Vanhua chemical) into the liquid, continuously stirring for reacting for 8 hours, and performing suction filtration and drying to obtain the isocyanate modified graphene oxide.

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 36g of diphenylmethane diisocyanate is taken in a flask, 0.18g of graphene oxide is added and stirred uniformly, after the mixture is heated to 65 ℃, 52.7g of PTMG with the molecular weight of 1000 is added in 3 times in total, and the prepolymer is obtained after the reaction for 5 hours. The NCO content of the resulting prepolymer was 8.6% by weight.

34g of pentaerythritol tetramercaptopropionate (Jingbo) and 0.7g of surface-modified graphene oxide were heated to 55 ℃ and stirred for mixing for 2 hours, 42g of isocyanate-terminated prepolymer was added thereto and stirred for deaeration, and the combined solution was poured into a mold. Heating the mould to 100 ℃ for curing for 15 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Example 2

Preparing a surface modification nano material:

5g of nano zinc oxide (TCI, the average particle size of 75 nm) is ultrasonically dispersed in dimethyl sulfoxide (Annaiji chemical) solvent, 0.36g of dibutyltin dibutyrate (Jinnanjin chemical Co., ltd.) is added, the mixture is heated to 90 ℃ and uniformly stirred, 22.5g of hydrogenated xylylene diisocyanate (Wanhua chemical) is added into the liquid, the mixture is continuously stirred and reacts for 10 hours, and the isocyanate modified nano zinc oxide is obtained through suction filtration and drying.

Preparation of an end-point detection window:

an isocyanate terminated prepolymer is first prepared. 53g of toluene diisocyanate is taken in a flask, 3.5g of nano zinc oxide is added and stirred uniformly, 139g of PTMG with the molecular weight of 1500 is added in 3 times after the mixture is heated to 80 ℃, and a prepolymer is obtained after reaction for 7 hours. The NCO content of the resulting prepolymer was 9.2% by weight.

Taking 32g of trimethylolpropane tris (2-mercaptoacetate) (Zhengzhou Achrom chemical industry) and 2.2g of surface-modified nano zinc oxide, heating to 60 ℃, stirring and mixing for 3 hours, adding 63g of isocyanate-terminated prepolymer into the mixture, stirring and defoaming, and injecting the combined solution into a mold. Heating the mould to 110 ℃ for curing for 16 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Example 3

Preparing a surface modification nano material:

taking 8g of nano zinc oxide (TCI) to be ultrasonically dispersed in a methanol (Anniji chemical) solvent, adding 0.31g of dibutyltin dibutyrate (Jinnanjin chemical Co., ltd.), heating to 110 ℃, uniformly stirring, adding 20g of hydrogenated xylylene diisocyanate (Wanhua chemical) into the liquid, continuously stirring for reacting for 13 hours, and carrying out suction filtration and drying to obtain the isocyanate modified nano zinc oxide.

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 47g of diphenylmethane diisocyanate was put into a flask, 1.8g of nano zinc oxide was added and stirred uniformly, after heating to 90 ℃, 114g of PTMG with a molecular weight of 2000 was added in 3 times in total, and a prepolymer was obtained after 6 hours of reaction. The NCO content of the resulting prepolymer was 6.81% by weight.

28g of trimethylolpropane tris (2-mercaptoacetate) (chemical industry of Akebia, zhengzhou) and 6.1g of surface-modified nano zinc oxide were taken, heated to 60 ℃, stirred and mixed for 3 hours, 40g of isocyanate-terminated prepolymer was added thereto, stirred and defoamed, and the combined solution was injected into a mold. Heating the mould to 130 ℃ for curing for 12 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 1

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 53g of toluene diisocyanate was put in a flask, heated to 80 ℃, 139g of PTMG with a molecular weight of 1500 was added in 3 times in total, and reacted for 7 hours to obtain a prepolymer. The NCO content of the resulting prepolymer was 9.2% by weight.

63g of the prepolymer, 32g of trimethylolpropane tris (2-mercaptoacetate) (Ank chemical, zheng) were placed in a mold, the mold was heated to 110 ℃ and cured for 16 hours, and finally cooled to 25 ℃ over 2 hours, and the sample was taken out for subsequent testing.

Comparative example 2

Preparing a surface modification nano material:

taking 3g of graphene oxide (SIGMA ALDRICH) to be ultrasonically dispersed in N, N-dimethylformamide (Shanghai aladine) solvent, adding 0.05g of di-N-butyltin dichloride (Shanghai Michell chemical technology Co., ltd.), heating to 80 ℃, uniformly stirring, adding 3.6g of isophorone diisocyanate (Wanhua chemical), continuously stirring for reacting for 8 hours, and performing suction filtration and drying to obtain the isocyanate modified graphene oxide.

Preparation of an end-point detection window:

an isocyanate terminated prepolymer is first prepared. 36g of diphenylmethane diisocyanate was put in a flask, heated to 65 ℃, and then 52.7g of PTMG with a molecular weight of 1000 was added in 3 times in total to react for 5 hours to obtain a prepolymer. The NCO content of the resulting prepolymer was 8.6% by weight.

34g of pentaerythritol tetramercaptopropionate (Jingbo) and 0.7g of surface-modified graphene oxide were heated to 55 ℃ and stirred for 2 hours, 42g of isocyanate-terminated prepolymer was added thereto and stirred for deaeration, and the combined solution was poured into a mold. Heating the mould to 100 ℃ for curing for 15 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 3

Preparation of an end-point detection window:

34g of pentaerythritol tetramercaptopropionate (Kyobo) was added to 42g of the isocyanate terminated prepolymer, stirred and defoamed, and the combined solution was poured into a mold. Heating the mould to 100 ℃ for curing for 15 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 4

Preparing a surface modification nano material:

dispersing 5g of nano zinc oxide (TCI) in dimethyl sulfoxide (Annaiji chemical) solvent by ultrasonic, adding 0.36g of dibutyltin dibutyrate (Jinnanjin chemical Co., ltd.), heating to 90 ℃, stirring uniformly, adding 22.5g of hydrogenated xylylene diisocyanate (Wanhua chemical) into the liquid, continuing stirring for reaction for 10 hours, and performing suction filtration and drying to obtain the isocyanate modified nano zinc oxide.

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 53g of toluene diisocyanate was put into a flask, 0.025g of dibutyltin dichloride (alatin) was added and stirred uniformly, after heating to 80 ℃, 139g of PTMG with a molecular weight of 1500 was added in 3 times in total, and a prepolymer was obtained after reaction for 7 hours. The NCO content of the resulting prepolymer was 9.2% by weight.

32g of trimethylolpropane tris (2-mercaptoacetate) (chemical industry of Akebia, zhengzhou) and 2.2g of surface-modified nano zinc oxide were heated to 60 ℃ and stirred and mixed for 3 hours, 63g of isocyanate terminated prepolymer was added thereto and stirred and defoamed, and the combined solution was injected into a mold. Heating the mould to 110 ℃ for curing for 16 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 5

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 53g of toluene diisocyanate is taken in a flask, 3.5g of nano zinc oxide is added and stirred uniformly, 139g of PTMG with the molecular weight of 1500 is added in 3 times after the mixture is heated to 80 ℃, and a prepolymer is obtained after reaction for 7 hours. The NCO content of the resulting prepolymer was 9.2% by weight.

Taking 32g of trimethylolpropane tris (2-mercaptoacetate) (Zhengzhou Achrom chemical industry) and 2.2g of nano zinc oxide, heating to 60 ℃, stirring and mixing for 3 hours, adding 63g of isocyanate-terminated prepolymer into the mixture, stirring and defoaming, and injecting the combined solution into a mold. Heating the mould to 110 ℃ for curing for 16 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 6

Preparation of an end-point detection window:

first an isocyanate terminated prepolymer is prepared. 36g of diphenylmethane diisocyanate was put in a flask, heated to 65 ℃, and then 52.7g of PTMG with a molecular weight of 1000 was added in 3 times in total to react for 5 hours to obtain a prepolymer. The NCO content of the resulting prepolymer was 8.6% by weight.

34g of pentaerythritol tetramercaptopropionate (Kyobo) and 19g of alumina particles (Shanghai Huaming, average particle diameter 90 nm) were heated to 55 ℃ and stirred for 2 hours, 42g of isocyanate terminated prepolymer was added thereto and stirred for deaeration, and the combined solution was poured into a mold. Heating the mould to 100 ℃ for curing for 15 hours, and finally cooling to 25 ℃ for 2 hours and demoulding to obtain the product.

Comparative example 7

Preparing a surface modification nano material:

a500-ml round-bottom flask was taken, 200ml of toluene and 0.147mol of nano ZnS particles (Shanghai well Macrochemical, average particle diameter 50 nm) were added to the flask, and stirring was carried out to uniformly disperse ZnS. After ZnS is dispersed uniformly, 0.288mol of trimethyloctadecyl ammonium chloride (Sigma-Aldrich) is added into the flask, and the mixture is stirred and reacted for 5h at 110 ℃ to finally obtain a mixed solution with white precipitate. Taking away the supernatant, washing the precipitate with ethanol and centrifuging, repeating the operation three times, and drying in a vacuum drying oven at 100 ℃ to obtain the surface modified ZnS powder.

Preparation of an end-point detection window:

48g of hydrogenated xylylene diisocyanate was added with 0.005g of modified ZnS powder at 20 ℃ and stirred to obtain an isocyanate solution in which nano ZnS was uniformly dispersed. After complete dissolution, 0.05g of the catalyst di-n-butyltin dichloride (carbofuran) and 0.02g of the internal mold release agent ZELEC UN (Stepan) were added to the isocyanate and dissolved sufficiently to obtain a solution A. 27g of 1, 2-bis (thio (2-mercaptoethyl)) -1-n-propanethiol (Jingbo) and 25g of pentaerythritol (mercaptopropionate) (Jingbo) are stirred and mixed uniformly to obtain a component B. A. Mixing the two components B at 20 ℃, pouring the mixture into a specific mould, heating the mixture from 30 ℃ for 18h to 120 ℃ for curing, and finally demoulding to obtain the product.

Examples 1,2, and 3 the resulting endpoint detection windows were prepared and tested for light transmittance, yielding the data of fig. 1-3.

After the prepared end point detection window is immersed in deionized water for 24 hours, the sizes of the end point detection window in the X and Y directions before and after immersion are measured, and the linear size change is recorded to obtain the data in Table 1. In the present invention, the higher dimensional stability obtained by the test represents better hydrolysis resistance. After the end point detection window soaked in the deionized water was placed under a light source with a wavelength of 400nm and continuously irradiated for 24 hours, the transmittance of the end point detection window was measured, and the data in table 2 and fig. 3 to 13 were obtained.

As can be seen by comparing the transmittance data in tables 1 and 2 and fig. 1 to 13, the endpoint detection windows obtained in examples 1,2 and 3 have high transmittance, and have high dimensional stability after being soaked in deionized water for 24 hours, and have transmittance of >80% in the full band after being subjected to photodegradation and hydrolysis tests.

Comparative example 1 the endpoint detection window was not added with surface-modified nanomaterials or unmodified nanomaterials, resulting in a substantial decrease in light transmittance at low wavelengths after hydrolysis and photodegradation, while negatively affecting the full-band light transmittance. In the comparative example 2, only the surface-modified graphene oxide is added, so that the light transmittance of the obtained endpoint detection window under low-wavelength light is greatly reduced, and the hydrolysis resistance is also poor. In the comparative example 3, only unmodified graphene oxide is added, and the obtained endpoint detection window has poor hydrolysis resistance and has negative influence on the light transmittance under full-wave-band visible light. Comparative example 4 in the preparation of prepolymer process is not added unmodified nano material but conventional catalyst, the obtained endpoint detection window shows a phenomenon of greatly reduced light transmittance in the full wave range. In comparative example 5, unmodified zinc oxide was added to the polyurethane reaction product instead of surface-modified zinc oxide, and the resulting endpoint detection window had poor hydrolysis resistance. Comparative example 6 and comparative example 7 are end point detection windows obtained according to the proposed technical solutions of patent CN1744968A and patent CN110627981A, respectively, which do not have excellent hydrolysis resistance.

Therefore, the co-addition and interaction of the surface-modified nano material and the unmodified nano material ensure that the endpoint detection window still has higher light transmittance under the action of photodegradation and hydrolysis conditions, and shows good hydrolysis resistance and photodegradation resistance.

TABLE 1 hydrolysis resistance test Linear dimensional data

Table 2 light transmittance data

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Claims

1. A light endpoint detection window comprises the following raw materials:

50-70 parts by mass of an isocyanate-terminated prepolymer;

30-50 parts by mass of a curing agent;

0.1-10 parts by mass of a surface-modified nano material;

wherein the sum of the isocyanate terminated prepolymer and the curing agent is 100 parts by mass;

the surface modified nano material is isocyanate surface modified nano material; the isocyanate is selected from alicyclic isocyanates containing at least one cyclic structure;

the nano material is selected from graphene oxide and/or nano zinc oxide;

the preparation method of the surface modified nano material comprises the following steps: ultrasonically dispersing the nano material in a solvent, adding a catalyst, heating and stirring uniformly at the heating temperature of 50-120 ℃, then adding isocyanate, continuously heating and stirring for 4-15 h, and performing suction filtration to obtain a surface modified nano material; the addition amount of the isocyanate for surface modification of the nano material is 100-500% of the mass of the nano material;

the isocyanate-terminated prepolymer is prepared from raw materials consisting of isocyanate, an unmodified nano material and polyol; in the isocyanate-terminated prepolymer, the amount of the unmodified nano material accounts for 0.1-3% of the sum of the mass of the isocyanate and the mass of the polyol;

the curing agent is at least one selected from pentaerythritol tetramercaptoacetate, pentaerythritol tetramercaptopropionate, trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), bis (mercaptoethyl) sulfide, bis (mercaptomethylthio) methane, bis (2-mercaptoethylthio) methane, bis (3-mercaptopropylthio) methane, 1,2, 3-tris (mercaptomethylthio) propane, and 1,2, 3-tris (2-mercaptoethylthio) propane.

2. The optical endpoint detection window of claim 1, wherein the nanomaterial is1 to 100nm in size.

3. The optical endpoint detection window of claim 1, wherein the isocyanate-terminated prepolymer is prepared by a process comprising the steps of: heating isocyanate to 60-120 ℃, adding the nano material, uniformly mixing, adding the polyol compound, and stirring for reaction for 2-8 hours to obtain the isocyanate-terminated prepolymer.

4. The optical endpoint detection window of claim 1, comprising the following raw material reaction preparation:

55-65 parts by mass of an isocyanate-terminated prepolymer;

35-45 parts of a curing agent;

0.5-5 parts by mass of a surface-modified nano material.

5. The optical endpoint detection window of claim 1, wherein the isocyanate of the isocyanate surface modified nanomaterial is selected from hydrogenated xylylene diisocyanate and/or isophorone diisocyanate.

6. The optical endpoint detection window of claim 1, wherein the nanomaterial is 20 to 80nm in size.

7. A method of making the optical endpoint detection window of claim 1, comprising the steps of: firstly, stirring and mixing the surface modified nano material and a curing agent at 50-70 ℃ for 2-3 hours, then adding the mixture into an isocyanate-terminated prepolymer, stirring and defoaming, injecting the obtained combined solution into a mold, heating the mold to 80-130 ℃, curing for 12-18 hours, cooling to 20-30 ℃ for 1-3 hours, and demolding.