WO2018000295A1

WO2018000295A1 - Phosphonate modified metal oxide particle

Info

Publication number: WO2018000295A1
Application number: PCT/CN2016/087832
Authority: WO
Inventors: Nan HU; Jinfei Wang; Mitsuru HAGA; Hongyu Chen; Yuanqiao Rao; Yi Zhang
Original assignee: Dow Global Technologies Llc; Rohm And Haas Electronic Materials Llc
Priority date: 2016-06-30
Filing date: 2016-06-30
Publication date: 2018-01-04
Also published as: JP2019524608A; CN109312102A; KR20190022656A; EP3478755A1; TW201808812A

Abstract

Phosphonate group modified metal oxide particles, a method for forming the phosphonate group modified metal oxide particles and a material containing the phosphonate group modified metal oxide particles are disclosed. The metal oxide particles have low crystallinity and provide materials with high refractive indices (RIs) and high transparency.

Description

PHOSPHONATE MODIFIED METAL OXIDE PARTICLE

Field

The present invention relates generally to a phosphonate group modified metal oxide particle, a method of forming the phosphonate group modified metal oxide particle and a material containing the phosphonate group modified metal oxide particle. In particular, the present invention relates to a phosphonate group modified metal oxide particle with low crystallinity, which is easily dispersed in organic materials and provides organic materials with high refractive index (RI) and high transparency.

Introduction

Electronic components are normally covered by organic coating materials to prevent them from oxidation or corrosion. For example, indium tin oxide (ITO) has been used as transparent electrodes on touch screen panels, and is also coated by organic coating materials. Normally, ITO electrodes are mounted on a glass substrate, then an insulating material as the protective layer is applied over the ITO electrodes. Typically, an acrylic or polysiloxane type polymer composition is used for insulating layers of ITO electrodes, but these insulating layers often make ITO electrodes visible. The reason is that the refractive indices (RI’s ) of these insulating layers (1.5-1.6) and the RI of ITO electrodes (1.8-2.2) are quite different, and the difference in RIs causes strong light reflection on the interface between the insulating layer and ITO electrodes, making ITO electrodes visible. The light reflection greatly reduces light transmittance of displays and causes correspondingly lower visual performance of the displays. To avoid this problem, one solution is using insulating layers having the same or quite similar RI value as that of ITO electrodes. Another solution is forming an anti-reflection layer (akind of insulating layer) between ITO electrodes and topcoat (the most outside insulating layer) , in which the anti-reflection layer has an intermediate RI (1.7-1.9) between the RI of ITO electrodes and the RI of the topcoat. Therefore, an insulating layer having a higher RI than the RI of the original insulating material is desired.

Metal oxide particles such as titanium oxide (TiO₂) and zirconium oxide (ZrO₂) are added in organic materials to increase the RI of the organic materials. Some prior art references disclose organic materials comprising metal oxide particles, for example, US6,521,677B, US201030174904A, WO2008/0588849A, JP4,917,196B, WO2012/058271A, US8,133,931B, US8,530,545B and US6,329,058B.

Metal oxide particles with large diameter decrease transparency of organic materials because light directed to an organic material is reflected by such large particles. In addition, even if meal oxide particles with small diameter are used, such metal oxide particles tend to agglomerate in organic materials. These agglomerated metal oxide particles act like a large particle and also decrease transparency of the organic materials. Therefore, a metal oxide particle having a small diameter and an ability of easily dispersing in organic materials is still desired.

Summary

The present invention provides a metal oxide particle modified by an organic compound having at least one phosphonate group, which prevents agglomeration of metal oxides in organic materials.

One aspect of the invention relates to a metal oxide particle with 60 ％or less of crystallinity, in which the surface of the particle is modified by (a) an organic compound having at least one phosphonate group and optionally (b) an organic silane compound.

In another aspect, the invention relates to a method for forming the metal oxide particle comprising the steps of: (a) condensating metal alkoxide in a solution to form a metal oxide particle with 60 ％or less of crystallinity, (b) contacting the metal oxide particle with an organic compound having at least one phosphonate groups to modify the metal oxide particle, and (c) optionally contacting the organic compound modified metal oxide particle with an organic silane compound.

In yet another aspect, the invention relates to a polymer material comprising a polymer and the metal oxide particle.

In further aspects, the inventions relate to a radiation sensitive composition comprising the metal oxide particle, and a material formed from the composition.

In yet further aspect, the invention relates to a reaction product obtained from the steps of: (a) contacting metal alkoxide with an acid to form a metal oxide particle, and (b) contacting the metal oxide particle with an organic compound having at least one phosphonate group, then (c) optionally contacting the organic compound modified metal oxide particle with an organic silane compound.

Brief description of the Drawings

Fig. 1 is a correlation between the amounts of metal oxide particles and RI, obtained in Example 1.

Fig. 2 is NMR chart for metal oxide particles without chlorotrymethylsilane treatment obtained in Example 2.

Fig. 3 is NMR chart for metal oxide particles with chlorotrymethylsilane treatment obtained in Example 2.

Fig. 4 is the developed patterns on silicon wafer obtained in Example 11.

Detailed Description

In this application, the word “ (meth) acrylate” includes both acrylate and methacrylate. In this application, the metal oxide particle modified by an organic compound having at least one phosphonate group is also called as “phosphonate group modified metal oxide particle” .

The metal oxide particle used in the present invention has 60 or less of crystallinity. Generally, metal oxide particles have many hydroxyl groups on the surface of the particles. The number of hydroxyl groups on the surface of particles with 60 or less of crystallinity is higher than the number of those with more than 60 of crystallinity. Therefore, to select such metal oxide particle with low crystallinity, sufficient surface treatment on the surface of the particle can be conducted as disclosed later. In addition, generally the degree of agglomeration of metal oxide particles with low crystallinity in organic solvents is smaller than that of high crystallinity, thus the particle with low crystallinity can easily dispersed in organic materials.

The crystallinity of the metal oxide particle used in the present invention is preferably 55 or less, more preferably 50 or less. The crystallinity of metal oxide particle can be analyzed and calculated as follows: i) prepare a 50: 50 mixture sample by weight of metal oxide particles with iron metal powders, ii) scan the 50: 50 mixture sample by X-ray diffraction with Cu-K_α radiation, between 20 and 52 degrees (2θ) using a 0.05 degree step interval and 12 second counting time respectively, iii) determine peak areas for the anatase (101) , (103) , (004) , (112) and (200) and calculate the sum of the area for the sample (A_anatase) , iv) determine peak area of iron peak (A_i) , v) calculate the ratio of anatase peak area to iron peak area for the sample (A_anatase/A_i＝R_exp) , vi) prepare a reference of metal oxide particles as an anatase standard, and conduct the same process above. Then calculate the ratio of anatase peak area of the standard to iron peak area (A_anatase-std/A_i＝R_std) , vii) calculating the ratio of R_exp and R_std above to determine crystallinity of the metal oxide particles (Wt％anatase) . For reference (anatase standard) , commercially available metal oxide particles with known crystallinity such as Catalogue #23203-3 from Aldrich Chemical can be used. The following formulas shown in Table 1 are refered to calculate the crystallinity of the metal oxide particles.

Table 1

Metal oxide particles having low crystallinity have a lot of hydroxyl groups on the surface of the particles. The number of hydroxyl groups on the surface of metal oxide particles having low crystallinity is larger than the metal oxide particles having high crystallinity. The reason is that the synthesis of metal oxide particles is normally conducted by continuous hydrolysis and condensation reaction of metal oxide precursors. For example, titanium oxide (TiO₂) particles are prepared from titanium alkoxyde (aprecursor of TiO₂) by continuous hydrolysis and condensation reaction. The synthesized TiO₂ particles have many -Ti-O-Ti-bonds structure in the particles. At the same time, unreacted alkoxyde groups of the titanium precursor become hydroxyl groups in the TiO₂ particles. High condensated TiO₂ particles have a large amount of -Ti-O-Ti-bond structures in the particles thus those TiO₂ particles have a small amount of residual hydroxyl groups. Since high condensated TiO₂ particles have high crystallinity measured by the above method, the metal oxide particles having high crystallinity have a small amount of hydroxyl groups. On the contrary, low condensated TiO₂ particles are TiO₂ particles with low crystallinity, and these have a large amount of residual hydroxyl groups.

The metal oxide particle used in the present invention is preferably selected from metal oxide particles comprising at least one of TiO₂, ZrO₂ and hafnium oxide. More preferably, the metal oxide particle is TiO₂ particle. The metal oxide particle can comprise two or more metal oxides.

The metal oxide particle used in the present invention is modified by an organic compound having at least one phosphonate group. Since the surface of the particle is modified by the organic compound, the phosphonate group modified metal oxide particle can disperse both in organic solvents and organic materials such as polymer materials. In particular, the phosphonate group modified metal oxide particle of the present invention can disperse in organic solvents normally used for electronic materials. Not bound to the theory, but inventors of the invention think that the phosphonate group of the organic compound reacts with a hydroxyl group on the surfaces of the metal oxide particles, and these organic compounds attached to the surface of the metal oxide particles prevent from agglomeration of these particles each other. Since the metal oxide particles having low crystallinity have a lot of hydroxyl groups, a large amount of organic compound can react with hydroxyl groups on the surface of such particles.

Preferably, the organic compound having at least one phosphonate group has acrylate or methacrylate group. Not bound to the theory, but inventors of this invention think that acrylate group or methacrylate group on the surface of the metal oxide particles have affinity with organic solvents especially the organic solvents used for electronic materials such as PGME and PGMEA, thus the metal oxide particles modified by those organic compound can disperse in organic solvents well.

The amount of attached organic compound having at least one phosphonate group to the surface of the metal oxide particles is preferably more than 0.78 per square nanometers (/nm²) , more preferably 0.80 or more per square nanometers of the surface of the metal oxide particles. It can be calculated by diameter, density and weight fraction of the metal oxide particles. The following formula is an example of the calculation of the amount of attached organic compound when metal oxide particles are TiO₂ particles.

In the formula, d_TiO2 is the particle diameter of the TiO₂ particles, and it can be analyzed by DLS. ρ_TiO2 is the density of the TiO₂ particles from gas pycnometer (carrier gas is helium) . Wt_TiO2-EMP is weight fraction of the TiO₂ particles and it can be obtained from TGA results. M_EMP is the molecular weight of TiO₂ particles and is 210.12 g/mol. Na is Avogadro constant 6.022*10²³ mol^-1.

The ratio of the amounts of residual hydroxyl groups and attached organic compound on the surface of the metal oxide particles can be analyzed and calculated by NMR spectrum.

The metal oxide particle can be further treated with organic silane compounds following the treatment with organic compound having at least one phosphonate group. The organic silane compounds react with residual hydroxyl groups on the surface of phosphonate group modified metal oxide particle. The surface treatment with such organic silane compounds decrease the number of residual hydroxyl groups on the surface of the phosphonate group modified metal oxide particle, and those metal oxide particles are much easier dispersing in organic solvents and organic materials compare with the metal oxide particles without organic silane compounds treatment. Preferably, the number of residual hydroxyl groups on the surface of the metal oxide particle are 1/20 or less in comparison with the number of residual hydroxyl groups before the treatment with the organic silane compounds. More preferably, the residual hydroxyl groups on the surface of the metal oxide particle are 1/50 or less in comparison with the one before the treatment with the organic silane compounds.

When the metal oxide particle is treated with organic silane compounds following to the treatment by organic compound having at least one phosphonate group, the molar ratio of the organic compound having at least one phosphonate group and the organic silane compound on the surface of the metal oxide particle are from 99: 1 to 1: 1, preferably from 20 : 1 to 2 : 1.

The diameters of phosphonate group modified metal oxide particles of the present invention have a range of diameters (distribution) . The diameters of 80 ％of the particles are from 0.5 to 150 nm. Preferably, the diameters of 80 ％of the particles are from 1 to 100 nm, more preferably, from 1 to 50 nm. The most preferably, the diameters of 80 ％of the particles are from 1 to 10 nm. The diameter can be measured by dynamic light scattering (DLS) method using DLS analyzer for example, Malvern Zetasizer Nano ZS, at room temperature. Smaller particle diameters provide higher transparency of an organic material comprising the particles.

The method for forming the phosphonate group modified metal oxide particles comprises the following three steps: (a) condensating metal alkoxide in a solution to form a metal oxide particle with 60％or less of crystallinity, (b) contacting the metal oxide particle with an organic compound having at least one phosphonate groups to modify the metal oxide particle, and optionally (c) contacting the phosphonate group modified metal oxide particle with an organic silane compound.

Step (a)

The first step is condensating metal alkoxide in a solvent to form a metal oxide particle with 60％or less of crystallinity. Examples of metal alkoxide include, but are not limited to, tetrabutoxy titanium, tetraethoxy titanium, tetramethoxy titanium, tetrabutoxy zirconium, tetraethoxy zirconium, zirconium n-propoxide, zirconium iso-propoxide and hafnium ethoxide. The solvent can be water or a mixture of water and other organic solvents.

Normally, condensating of metal alkoxyde is conducted in water under the presence of hydrolysis catalyst (acid or base) . The condensate reaction in water is understood as hydrolysis and condensation reaction in the art. It is also known as sol-gel reaction. The concentration of metal alkoxyde in the solution is from 150 to 400 g/L, preferably from 200 to 350 g/L, more preferably from 250 to 300 g/L. Acid as a catalyst can be organic acid or inorganic acid. Examples of such acid include, but are not limited to, hydrochloric acid, sulfuric acid, formic acid and acetic acid. The concentration of the acid in the solution is from 2.5 to 12.0 g/L, preferably from 4.5 to 8.5 g/L. A base can be used instead of an acid as a hydrolysis catalyst. When base is used as a hydrolysis catalyst, its concentration in the solution can be decided based on the technical knowledge for the art. Optionally, a solvent such as methanol, ethanol or butanol can be added in the solution.

The reaction temperature is from 30 to 80 ℃, preferably from 60 to 80 ℃. The condensate reaction is conducted under stirring. The reaction time is from 1.5 hours to 5 hours, preferably from 3 to 4 hours. As the condensation reaction is proceeding, the size of metal oxide particles become bigger. When metal oxide particles with required particle sizes are obtained, the first step is finalized. As mentioned before, particle size (diameter of the particles) can be measured by DLS.

Step (b)

The second step is contacting the metal oxide particles with an organic compound having at least one phosphonate group to modify the metal oxide particle. Examples of the organic compounds having at least one phosphonate group include, but are not limited to, alkylene (meth) acrylate phosphates such as ethylene methacrylate phosphate and ethylene acrylate phosphate； and poly (alkylene oxide) (meth) acrylate phosphates such as disclosed as the following formulas (1) to (3) .

In the formulas (1) to (3) , n is an integer from 1 to 20.

As disclosed in Examples, vinyl phosphonic acid cannot be used individually for the surface treatment of the present invention, because the metal oxide particles treated with the compound is not dispersed in organic solvents used for polymer materials of electronic materials.

The amount of the organic compound having at least one phosphonate group can be decided based on the weight ratio with metal alkoxyde which is used in step (a) . The weight ratio of metal alkoxide with the organic compound having at least one phosphonate group is from 10 : 1 to 1 : 10, preferably from 5 : 1 to 1 : 2. The metal oxide particles are contacted with the organic compound by any known method, for example, the metal oxide particles and the organic compound are mixed in a solvent such as water under stirring. Reaction temperature is from 60 to 150 ℃, preferably from 80 to 120 ℃. Reaction time is from 0.25 to 12 hours, preferably from 1 to 4 hours.

Step (c)

The third step is optional and is contacting the phosphonate group modified metal oxide particles with an organic silane compound. Examples of the organic silane compounds include, but are not limited to, trialkyl chloro silanes such as trimethyl chlorosilane, triethyl chlorosilane and tripropyl chlorosilane and silazanes such as hexamethyldisilazane. The amount of the organic silane compound can be decided based on the weight ratio with metal alkoxyde which is used in step (a) . The weight ratio of the metal alkoxide with the organic silane compounds is from 20 : 1 to 1 : 10, preferably from 10 : 1 to 1 : 1. The phosphonate group modified metal oxide particles are contacted with the silane compound by any known method, for example, the phosphonate modified metal oxide particles and the organic silane compounds are mixed in a solvent such as water under stirring. Reaction temperature is from 30 to 150℃, preferably from 50 to 120 ℃. Reaction time is from 0.5 to 8 hours, preferably from 1 to 2 hours.

Obtained reaction product is cooled to room temperature, then optionally aged (left) for 12 to 24 hours. When a solvent such as water is used in step (b) and/or step (c) , the solvent of the reaction product can be exchanged to another solvent which is used to radiation sensitive compositions. Examples of the solvent used for radiation sensitive compositions include, but are not limited to, propyleneglycol monomethyl ether (PGME) , propylene glycol phenyl ether propyleneglycol monomethyl ether acetate (PGMEA) , 1-propoxy-2-propanol, ethyl lactate, methyl 2-hydroxyisobutyrate and cyclohexanone.

One aspect of the present invention is a polymer material comprising a polymer and the phosphonate group modified metal oxide particles. The polymer is also called as a binder. Examples of the polymer include, but are not limited to, acrylic type polymers, methacrylic type polymers, siloxane type polymers, epoxy resins, polyester, polyolefins, novolac resins, polystyrenes and polyurethane. The word “type” in those polymers includes copolymer which is formed from two or more different monomers, and a polymer formed from an ester of the monomer. For example, ‘acrylic type polymers’ include a copolymer formed from acrylic acid and at least one other monomer, as well as a polymer formed from acrylate such as methyl acrylate. Also, “polystyrenes” include any resins if the resins are formed from styrene and at least one other monomer. “Epoxy resins” means any resins if the resin comprises an epoxy group.

The polymer material can be a molded product, a film or any other forms. The polymer material can be a film formed on an object. Any objects can be used. Examples of the objects include, but are not limited to, plastics, metals, glass and electronic components such as ITO electrodes, wiring materials and glass or silicon substrates. When forming a film on an object, a composition comprising the polymer, the phosphonate group modified metal oxide particles and optionally solvent are prepared, then the composition can be coated on an object by any known methods such as spin coating. Optionally the composition is dried to evaporate the solvent.

The amount of the phosphonate group modified metal oxide particles in the polymer material can be from 0.1 to 80 wt％, preferably from 5 to 70 wt％. When the amount of the phosphonate group modified metal oxide particles are contained in the polymer material from 0.1 to 80 wt％, The RI of the polymer material comprising the phosphonate group modified metal oxide particles is from 1.65 to 2.0. When the organic material is used as an organic coating material of ITO electrodes, the RI of the polymer material containing the particle is preferably from 1.7 to 1.9.

A radiation sensitive composition of this invention comprises the phosphonate group modified metal oxide particles disclosed above. In general, there are two types of radiation sensitive compositions, i.e. positive type radiation sensitive composition and negative type radiation sensitive composition. Positive type radiation sensitive composition means a composition which forms a film in which the portion of the film that is exposed to radiation becomes soluble to developing compositions such as alkaline solutions, while negative type radiation sensitive composition forms a film in which the exposed portion becomes insoluble to developing compositions. The radiation sensitive composition of this invention can be positive type radiation sensitive composition or negative type radiation sensitive composition. The formulation of the radiation sensitive composition can be decided based on the knowledge of a person of ordinary skills in the art. Examples of negative type radiation sensitive composition is disclosed below.

Normally, negative type radiation sensitive composition comprises a radiation curable resin, a photo initiator, a solvent and additives. Radiation curable resin is a monomer or origomer which is crosslinked by exposure of radiation and forms a resin. It is also called as a multi-functional monomer. A radiation curable resin which forms an alkaline soluble resin is preferable. Radiation curable resins include, but are not limited to, compounds having epoxy group, oxetane group, vinyl group, thiol group or acryloyl group. Examples of the radiation curable resins include, but are not limited to, urethane acrylates, polyester acrylates, oxetane resins, polysiloxane and epoxy acrylates. The amount of the radiation curable resins is from 0 to 70 wt％, preferably from 5 to 60 wt％based on the solid contents of the radiation sensitive composition.

Any known photoinitiator (PI) such as oxime ester type photoinitiators, alkylphenone type photoinitiators and cationic type photoinitiators such as sulfonium salts or iodonium salts can be used. Examples of the PI include, but are not limited to, Irgacure OXE-01, Irgacure OXE-02, Irgacure 379, Irgacure 651, Irgacure 127 and Irgacure 907. The amount of a PI in the composition is from 0.001 to 5.0 wt ％, preferably from 0.01 to 3.0 wt％based on the solid contents of the radiation sensitive composition.

The radiation sensitive composition of this invention can comprise at least one solvent. Examples of solvents include, but are not limited to, propyleneglycol monomethyl ether (PGME) , propylene glycol phenyl ether propyleneglycol monomethyl ether acetate (PGMEA) , 1-propoxy-2-propanol, ethyl lactate, methyl 2-hydroxyisobutyrate and cyclohexanone. The total amounts of solvents are from 25 to 900 wt ％, preferably from 150 to 400 wt ％based on the solid contents of the radiation sensitive composition.

Examples of an additive used in the radiation sensitive composition of the invention include, but are not limited to, inhibitors, dispersants and coloring compounds such as dyes, pigments or carbon black.

The radiation sensitive composition can be applied to an object such as electronic components, by any known methods for example, spin-coating, roll-coating and spraying the composition on electronic components, or dipping electronic components in the composition.

Then the radiation sensitive composition is exposed to cure the composition. Expose can be conducted by UV light or visible light. Exposure is conducted with use of a pattern mask to obtain required pattern on an object. Then, unexposed area is removed away by a developing composition called as developer. Any known developer can be used. When the cured composition is alkaline soluble, alkaline developers are preferable. Examples of such developer include, but are not limited to, alkaline solutions comprising potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and tetrabutylammonium hydroxide. Optionally, the exposed compound can be further heated to 80 to 250 ℃ for 3 minute to 2 hours.

As disclosed above, the radiation sensitive composition forms a hardened material (cured material) by exposing, developing and optionally further heating. The hardened material can be used for forming an insulation layer (organic coating) on electronic components. The insulation layer includes an anti-reflection layer. Examples of the electronic components include, but are not limited to, ITO electrodes and wiring materials of the ITO electrodes used for LCD devices, OLED devices and touch screen sensor panels. Wiring materials include copper, silver and metal alloy containing copper or silver. When the hardened material formed from the composition of this invention is transparent or translucent, the hardened material is especially useful to form an insulating layer on ITO electrodes because it has high RI.

Examples

Raw materials shown in Table 2 were used in Examples.

Table 2

Example 1 (Inventive example)

A mixture of 150 g of titanium butoxide, 25.5 g of hexanoic acid, 50 mL of 1-butanol was added into Parr reactor and stirred. Deionized (DI) water (14.0g) was added into the reactor. The solution was stirred at room temperature for 0.5 hour. Afterwards the solution was heated at 135 ℃ for 2.5 hours. TiO₂ particles were observed.

Ethylene methacrylate phosphate (EMP, 21.5 g) was dissolved into 21.5 g of PGMEA and added into the reactor containing TiO₂ particles solution. The solution was heated at 115 ℃ for 1 hour and cooled to room temperature. TiO₂ particles modified by EMP (TiO₂-EMP particles) were obtained.

Chlorotrimethylsilane (5.0 g) was added into the above reactor containing TiO₂-EMP particles solution and the solution was heated at from 60 to 80 ℃ for 1 hour to react with hydroxyl group on the surface of TiO₂-EMP particles. TiO₂ particles modified by EMP and chlorotrimethylsilane (TiO₂-EMP/CMS particles) were obtained.

N-hexane (3 times volume to reaction solution) was added into the solution to precipitate the obtained TiO₂-EMP/CMS particles. The precipitant was collected by centrifugation and re-dissolved into PGMEA. A transparent dispersion with pale yellow color was obtained. The dispersion is referred to as TiO₂-EMP/CMS with solid content of 35 wt％.

Analysis

Crystal structure

The crystal structure was examined by X-ray diffraction (XRD) . XRD measurement was carried out with Bruker D8 ADVANCE diffractometer equipped with a copper rotating anode, a diffracted beam monochromator tuned to Cu Kα radiation, and a scintillation detector.

The X-ray diffraction pattern indicated that the crystal structure of TiO₂-EMP/CMS particle is anatase.

Particle size

Particle size of the TiO₂-EMP/CMS particles was measured by dynamic light scattering (DLS, Malvern Zetasizer Nano ZS) . The TiO₂-EMP/CMS particles dispersed in 2-butanone were used to analyze its particle size. DLS curve indicated that the particle diameter ranges of the TiO₂-EMP/CMS particle are from 1.5 to 7 nm.

P³¹ NMR

Chemical environment of phosphonate groups of the TiO₂-EMP/CMS particles was measured by P³¹ NMR. P³¹ NMR peaks for the TiO₂-EMP/CMS particles were compared those of EMP. TiO₂-EMP/CMS dispersed in methyl ethyl ketone were used. The NMR data showed that the sharp peaks of free phosphonate groups of EMP disappeared in TiO₂-EMP/CMS particle sample, thus almost of EMP molecules have been attached to TiO₂ surface.

Organic composition contents

Organic composition of TiO₂-EMP/CMS particles was detected by thermal gravity analysis (TGA) . TGA curve indicated that the content of organic materials in the TiO₂-EMP/CMS particles is 21.3 wt％.

Crystallinity

The crystallinity of the TiO₂ particles was measured referring to US6329058B. Titania slurry before EMP treatment was dried under 50 ℃ overnight. Obtained titania powder was ground using a mortar and pestle. The X-ray diffraction was performed with Bruker D8 ADVANCE diffractometer equipped with a copper rotating anode, a diffracted beam monochromator tuned to Cu Kα radiation, and a scintillation detector.

Each particle sample was prepared as a 50: 50 mixture by weight with iron metal powder and scanned between 20 and 52 degrees using a 0.05 degree step interval and 12 second counting time. Peak areas for the anatase (101) , (103) , (004) , (112) , and (200) mixima and iron maximum were determined by profile fitting the observed data. A Gaussian peak shape model and linear background were employed for profile fitting. The ratio (R_exp) of anatase peak area (A_anatase) taken as the sum of the individual contributions indicated above, to iron (A_i) peak area, were calculated for each unknown. A reference anatase standard, commercially available as Catalogue #23203-3 from Aldrich Chemical was also scanned to provide a similar reference value (R_std) . The weight percent of anatase form in the crystalline metal oxide particles of the present invention were calculated by the instrument using the ratio of R_exp to R_std as follows:

A_anatase＝A ₍₁₀₁₎ +A ₍₁₀₃₎ +A ₍₀₀₄₎ +A ₍₁₁₂₎ +A ₍₂₀₀₎ (sum of individual anatase peak areas)

A_i (Area of iron peak)

R_exp＝A_anatase/A_i (Ratio of anatase peak area to iron peak area for unknown)

R_std＝A_anatase-std/A_i-std (Ratio of anatase peak area to iron peak area for stand anatase)

Wt ％anatase＝ (R_exp/R_std) *100 (Weight percent crystalline anatase)

The crystallinity of the TiO₂ particles was around 50 ％.

Acrylic photoresist MSP5727 and TiO₂-EMP/CMS dispersion in PGMEA were mixed with various weight ratios and casted onto silicon wafer by spin coating. Refractive Index (at 550 nm) of dry MSP5727/TiO₂-EMP/CMS films were analyzed. RIs of the films were increased as a function TiO₂-EMP/CMS content as shown in Fig. 1.

Example 2

The same process as of Example 1 was conducted excepting for PAM-100 (45.0 g) was used instead of EMP (21.5 g) . The TiO₂ particles treated with PAM-100 are called as TiO₂-PAM-100 particles, while the TiO₂ particles treated with PAM-100 then treated with CMS are called as TiO₂-PAM-100/CMS particles. The organic content of TiO₂-PAM/CMS particles was 57.6 wt％from TGA result.

The amounts of hydroxyl groups on the surface of TiO₂-PAM-100 particles and those of TiO₂-PAM-100/CMS particles were examined by ¹H NMR (Bruker AVANCE III 400 MHz spectrometer) . The test condition is as follows:

Temperature: Room temperature

Resonance frequency: 400.1 MHz

Probe: 5 mm BBI

Fig. 2 is NMR data for TiO₂-PAM-100 while Fig. 3 is NMR data for TiO₂-PAM-100/CMS. Referring to Fig. 2, there is obvious Ti-OH peak in ¹H NMR spectrum at 1.35 ppm. (Reference: Eiden-Assmann, S. ； Widoniak, J. ； Maret, G., Chem Mater 2004, 16 (1) , 6-11. ) Setting the proton from C＝C double bond as internal standard, the integrity value of Ti-OH is 42, which means that the molar ratio of Ti-OH and PAM-100 at TiO₂ surface is 42: 1. Referring to Fig. 3, the Ti-OH peak at 1.35 ppm is almost disappeared. Its integrity value is only 0.5. At this time the molar ratio of TiOH and PAM-100 at TiO₂ surface is only 0.5: 1. Therefore, the amounts of hydroxyl groups on the surface of particles after CMS treatment are decreased to around 1/84 before CMS treatment.

Example 3 (Comparative Example)

The same process as of Example 1 was conducted excepting for VPA (18.0g) was used instead of EMP (21.5 g) . The obtained TiO₂ particles were mixed with organic solvents. The particles were not dispersed in PGMEA, PGME and NMP at all.

Example 4 (Comparative Example)

The same process as of Example 1 was conducted excepting for commercialized anatase TiO₂ particles were used instead of synthesized TiO₂ particles. The obtained particles are called as TiO_{2 (commercial)} -EMP/CMS. The attached EMP number per unit surface in the TiO₂ particles were calculated and compared with those of TiO₂-EMP/CMS obtained in Example 1.

The attached EMP number per unit surface in TiO₂ particles equals (n)

wherein d_TiO2 is the particle diameter. Diameter of commercialized anatase TiO₂ is provided by supplier Aladdin. ρ_TiO2 are the densities of TiO₂ particle from gas pycnometer (carrier gas is helium) . Weight fractions Wt_TiO2-EMP were obtained from TGA results. M_EMP is the molecular weight 210.12 g/mol. Na is Avogadro constant 6.022*10²³ mol^-1.

Table 3

Examples 5 to 11

For Examples 5 to 10, compositions comprising TiO₂-EMP/CMS particles obtained in Example 1, radiation sensitive acrylic polymer (DPHA, or DPHA and carboxylic functioned resin) , photo initiators, inhibitor and ADP were prepared as shown in Table 4.

The compositions were spin-coated on a glass substrate. Spin speed was adjusted to obtain 1.8 μm of film thickness after soft bake process. 90 ℃ of soft bake was applied for 120 seconds on proximity hot plate of the coating tool. Film thickness was measured by light interference method (Lambda-A VL-M6000-LS, Screen) . Expose and develop step were conducted for the coated substrates. The coated substrate was exposed by broad band proximity exposure tool (MA-1200, Dainippon Kaken) with 600mJ/cm² of exposure dose. Integrate exposure energy was measured by i-line sensor (UV-M03A, Orc Manufacturing Co., ) . To obtain photo patterns, a photo mask (Multitone test pattern mask, Benchmark Technologies) was used. After exposure process, the substrate was developed by 2.38 wt％TMAH (tetramethylammonium hydroxide) aqueous solution for 60 seconds. After water rinse and spin dry process, 120 ℃ of hard bake cure was applied in a convection oven for 60 minutes. Refractive Indices of the obtained films at 550 nm were measured using ellipsometer. The values are also shown in Table 4. RI at 550 nm of a film which does not contain TiO₂-EMP/CMS particles was 1.523.

Table 4

For Example 11, the same process as of Example 8 was repeated but silicon wafer was used instead of glass substrate. An optical image taken by confocal microscope (H300, Lasertec Co. ) SEM photo is shown in Fig. 4.

Claims

A metal oxide particle with 60％ or less of crystallinity, in which the surface of the particle is modified by (a) an organic compound having at least one phosphonate group and optionally (b) an organic silane compound.
The metal oxide particle of claim 1, wherein the molar ratio of the organic compound and the organic silane compound is from 99: 1 to 1: 1.
The metal oxide particle of claim 1, wherein the metal oxide is at least one of titanium oxide and zirconium oxide.
The metal oxide particle of claim 1, wherein the organic compound is selected from ethylene methacrylate phosphate and poly (alkylene oxide) methacrylate.
The metal oxide particle of claim 1, wherein the organic silane is trialkyl chloro silane.
A method for forming the metal oxide particle of claim 1 comprising the steps of:

(a) condensating metal alkoxide in a solution to form a metal oxide particle with 60％ or less of crystallinity,

(b) contacting the metal oxide particle with an organic compound having at least one phosphonate groups to modify the metal oxide particle, and

(c) optionally contacting the organic compound modified metal oxide particle with an organic silane compound.
A polymer material comprising a polymer and the metal oxide particle of claim 1.
A radiation sensitive composition comprising the metal oxide particle of claim 1.
A material formed from the radiation sensitive composition of claim 8.
A reaction product obtained from the steps of:

(a) contacting metal alkoxide with an acid to form metal oxide particle, and

(b) contacting the metal oxide particle with an organic compound having at least one phosphonate group, then

(c) optionally contacting the organic compound modified metal oxide particle with an organic silane compound.