KR20210029915A - Method of modifying surface property of silica powder using non-aqueous vapor deposition and method for silica-metal core-shell complex - Google Patents

Abstract

The present invention relates to a method for surface modification of silica powder using a solvent-free vapor deposition process and a method for preparing a silica-metal core-shell complex. Particularly, the method for surface modification of silica powder using a solvent-free vapor deposition process includes the steps of: 1) introducing silica particle powder and a silane coupling agent into a reaction container; 2) allowing the reaction container to stand under vacuum; and 3) heat treating the reaction container in a vacuum oven at 100-150°C. In addition, the method for preparing a silica-metal core-shell complex includes a step of coating the surfaces of the surface-modified silica particles with a metal through an electroless plating process. The method for preparing a silica-metal core-shell complex allows surface modification of silica particles through the formation of a self-assembled mono-molecular film of -SH (thiol) and -NH_2 (amine) functional groups on the surface of silica particles by using a vapor deposition process using no solvent, wherein a cost-efficient silane coupling agent and processing conditions applicable to the industrial fields are derived and optimized.

Description

BACKGROUND OF THE INVENTION [0002] A method for modifying the surface of silica powder using a solvent-free vapor deposition method and a method for manufacturing a silica-metal core-shell composite {METHOD OF MODIFYING SURFACE PROPERTY OF SILICA POWDER USING NON-AQUEOUS VAPOR DEPOSITION AND METHOD FOR SILICA-METAL CORE-SHELL COMPLEX}

The present invention relates to a method for modifying a surface of silica powder and a method for preparing a silica-metal core-shell composite using a solvent-free vapor deposition method, and specifically, 1) placing a silica particle powder and a silane coupling agent inside a reaction vessel; 2) maintaining the reaction vessel under vacuum; And 3) a method for modifying the surface of silica powder using a solvent-free vapor deposition method including heat-treating the reaction vessel in a vacuum oven at 100 to 150°C, and the surface modified It provides a silica-metal core-shell composite manufacturing method comprising the step of coating a metal on the surface of the silica particles by using an electroless plating method of the silica particles.

In general, a conductive paste is an adhesive having electrical conductivity used for assembling wiring of electrical and electronic products or circuits, and refers to a paste composed of a binder such as a polymer resin and conductive particles such as metal particles. The conductive paste is a connection material in the assembly process of electric and electronic products and can be mounted and assembled at a process temperature lower than that of the conventional soldering process, so it is widely used in electric and electronic fields such as electronic component packaging and circuit interconnectors.

In the case of the conventional conductive paste, since precious metals such as gold (Au), silver (Ag), and palladium (Pd) are used as conductive powder, the price is high, and the price is relatively low such as nickel (Ni) and copper (Cu). In the case of using a metal powder, there is a problem in that electrical properties are reduced due to oxidation of the powder during firing. In general, silver powder is mainly used among precious metals, and there is a problem in that the cost of raw materials is large due to this, and efforts have been made to reduce the use of silver powder. However, when the amount of silver powder is reduced, the desired conductivity is not met, and even when partially mixed with silver powder, nickel, copper, aluminum, etc. as an alternative material for silver, there is a problem in that the conductivity and physical properties are similarly defective.

As a prior art, Korean Patent Application Publication No. 2009-0022757 relates to a conductive paste composition for an electrode including a silver coating powder and a method for manufacturing the same, and includes silver coated glass powder, inorganic binder, organic binder, solvent and additives. It discloses a conductive paste composition.

Korean Patent Registration No. 10-0895414

As precious metals such as gold and silver form a high price point, when used as a raw material, as it acts as a cause of an increase in the unit price, attempts to reduce material cost while maintaining the inherent characteristics of precious metals are being conducted. It was attempted to develop a low-cost silver particle with a structure.

In order to achieve the above object, 1) placing the silica particle powder and the silane coupling agent inside the reaction vessel; 2) maintaining the reaction vessel under vacuum; And 3) providing a method for surface modification of silica powder using a solvent-free vapor deposition method comprising the step of heat-treating the reaction vessel in a vacuum oven at 100 to 150°C.

The silane coupling agent is 3-aminopropyltriethoxysilane, (3-mercaptopropyl) trimethoxysilane ((3-Mercaptopropyl) trimethoxysilane), n-octyltriethoxysilane (n-octyl -triethoxy-silane), decyltrimethoxysilane, decyltrimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane (N,Nb is (2-hydroxyethyl)-3-aminopropyltriethoxy silane), 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxy-silane, or a combination thereof It may be, preferably (3-aminopropyl) triethoxysilane ((3-aminopropyl) triethoxysilane) or (3-mercaptopropyl) trimethoxysilane ((3-Mercaptopropyl) trimethoxysilane), but is not limited thereto.

The heat treatment step in step 3) is 100 to 150°C, preferably 130°C, and may further include washing _{UV/O 3 after step 3).}

The surface-modified silica particles have a water contact angle of 45 to 65°, and a CH ₂ I ₂ contact angle of 25 to 30°.

In another embodiment of the present invention, there is provided a method of manufacturing a silica-metal core-shell composite comprising the step of coating a metal on the surface of the silica particles using an electroless plating method on the silica particles surface-modified by the above method.

The metals are gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), tungsten (W), titanium (Ti), platinum (Pt), palladium (Pd), tin ( It is any one selected from the group consisting of Sn), lead (Pb) and zinc (Zn), preferably Ag or Ni.

The electroless plating method includes preparing a plating solution by mixing a metal salt to be coated, a complexing agent, a stabilizer, and a reducing agent; Mixing the surface-modified silica particles with the plating solution; and adding a pH adjusting agent to induce a reduction reaction.

In addition, the present invention provides a silica-metal core-shell composite manufactured by the above manufacturing method.

_{The method for preparing a silica-metal core-shell composite according to the present invention is a self-assembled monomolecular film of -SH (thiol) and -NH 2} (amine) functional groups on the surface of silica particles using a vapor deposition method that does not use any solvent on the surface of the silica particles. The silica surface can be modified through formation, and inexpensive silane coupling agent materials and process conditions applicable to industrial sites were derived and optimized. In addition, by manufacturing silver particles, which are in high demand as conductive materials in electronic products, at low cost, not only cost reduction in the final product, but also noise reduction, electromagnetic wave shielding, and heat dissipation, etc. can be expanded to increase the performance of the final product.

1 is a diagram showing an internal arrangement of a desiccator (left) and an actual photograph of a reactor (right).
2 is a view showing a water contact angle photograph of a silica substrate treated with ASP and MPS (top: Bare, middle: -NH ₂ , bottom: -SH).
_{3 is a view showing a picture of a CH 2} I ₂ contact angle of a silica substrate treated with ASP and MPS (top: Bare, middle: -NH ₂ , bottom: -SH).
4 is a diagram showing the TGA results of silica particles treated with ASP and MPS (left: -NH ₂ , right: -SH).
5 is a diagram showing the XPS results of the silica substrate treated with ASP and MPS (left: -NH ₂ , right: -SH).
6 is a diagram showing an SEM image of an Ag plating sample of silica particles surface-modified using ASP (top: existing silica particles, middle: NH ₂ modified silica particles before washing, bottom: UV/O _{3 NH 2} after washing) Modified silica particles).
7 is a diagram showing an SEM image of an Ag plating sample of silica particles surface-modified using MPS (top: conventional silica particles, middle: SH modified silica particles before washing, bottom: SH modified silica after _{UV/O 3 washing)} particle).

In an embodiment of the present invention, 1) placing a silica particle powder and a silane coupling agent inside a reaction vessel; 2) maintaining the reaction vessel under vacuum; And 3) providing a method for surface modification of silica powder using a solvent-free vapor deposition method comprising the step of heat-treating the reaction vessel in a vacuum oven at 100 to 150°C.

The method of modifying the surface of the silica powder is a surface treatment process necessary to coat a dense metal layer on the silica particles. The process involves placing silica particle powder and a silane coupling agent not suspended in a solvent in a reaction vessel, and then placing the reaction vessel in a vacuum state. It is characterized in that the conversion to and to proceed the reaction.

(3-Aminopropyl) triethoxysilane (APS) or (3-mercaptopropyl) trimethoxysilane (MPS) used in the examples of the present invention is each- Since it has SH and -NH ₂ functional groups at the same time, it forms a self-assembled monolayer (SAM) on the surface of the silica particles.

As a solution immersion method using a large amount of organic solvent, due to environmental issues, companies cannot actually apply the self-assembled monolayer (SAM) technology, but the present invention uses a vapor deposition method that does not use any solvent. Thus, it is possible to form a self-assembled monolayer of -SH (thiol) and -NH ₂ (amine) functional groups on the surface of the silica particles, thereby enabling the surface modification of the silica particles.

When the reaction vessel is not converted to a vacuum state, a silane coupling agent such as (3-aminopropyl) triethoxysilane (APS) or (3-mercaptopropyl) trimethoxysilane (MPS) is added after the reaction. The gelation phenomenon of gelation by reaction with moisture in the air was observed, and it was found that the silica powder also aggregated after the reaction, and part of it changed to a solid state. However, when the reaction vessel was subjected to the reaction in a vacuum state, the above gelation phenomenon was not observed because the contact with moisture in the atmosphere was blocked.

In step 3), the heat treatment step is 100 to 150°C, preferably 130°C, and when the heat treatment temperature is less than 100°C, dehydration on the surface of the reactant is not properly performed, and the condensation reaction between the reactants (APS, MPS) There is a disadvantage in that the covalent bonds between the reactants are not formed due to the lack of, and the bonding force of the surface modification is weakened. In addition, when the heat treatment temperature is 150°C or higher, the free energy of the reactants (APS, MPS) is increased to form an irregular monomolecular layer, and the decomposition of the CC bond may be caused, leading to the possibility of desorption of the surface-modifying agent. There is this.

In another embodiment of the present invention, there is provided a method of manufacturing a silica-metal core-shell composite comprising the step of coating a metal on the surface of the silica particles using an electroless plating method on the silica particles surface-modified by the above method.

The metals are gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), tungsten (W), titanium (Ti), platinum (Pt), palladium (Pd), tin ( It is any one selected from the group consisting of Sn), lead (Pb) and zinc (Zn), preferably Ag or Ni. In the case of forming a silica-metal core-shell composite using the surface-treated silica particles, a metal plating layer having a thicker layer compared to the existing silica particles was formed, and the present inventors provided high-quality core- It was confirmed that the formation of shell composite structure particles is possible.

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and drawings. These examples are only illustratively presented to explain the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples. .

In addition, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and in case of conflict, the present specification including definitions The description of will take precedence.

<Example>

1. Formation of self-assembled monolayers using vapor deposition

Silica particles purified from Microcomposite were received and used in experiments without additional pretreatment.

The silica particles were spread evenly inside the petri dish so that they were not thickly stacked. Thereafter, 0.5 ml of (3-Aminopropyl)trimethoxysilane (APS) and (3-Mercaptopropyl)trimethoxysilane (MPS) were each added to an aluminum dish, and then placed inside the petri dish. Thereafter, a Petri dish containing silica particles and an aluminum dish was placed in a desiccator, and then kept at room temperature and under vacuum for 12 hours. The desiccator used in the present invention is shown in FIG. 1.

After the reaction was completed, the silica particles were heat-treated in a vacuum oven at 130° C. for 1 hour to prepare _{SiO 2} -APS and SiO _{2 -MPS.}

2. Metal coating using electroless plating

After electroless plating method by using the coated Ag, Ni on the surface of _{SiO 2 -APS-Ag, SiO 2} -MPS-Ag, SiO 2 -APS-Ni and Ni-SiO ₂ -MPS the four silica-metal core-shell (Silica-metal core-shell) was prepared.

Ni metal was coated on the surface-treated silica particles by electroless plating. Calculate the appropriate amount of Ag or Ni metal salt (silver chloride or nickel chloride hexahydrate 30g), complexing agent (Rochel salt 40g), stabilizer (thiourea 100ppm), reducing agent (sodium hypophosphite 50g) in 1 liter of 50 degree distilled water according to the amount of metal coating And then stirred for 10 minutes to prepare a plating solution. After adding 20 g of the surface-treated silica particles having an average particle size of 30 μm to the plating solution based on a plating amount of 50 wt%, a pH adjusting agent (dissolving 10 g of sodium hydroxide in 100 ml distilled water) was added in a drop form to induce a reduction reaction. By generating an electroless chemical plating reaction, a silica-metal core-shell particle was finally prepared. After that, the washing and dehydration processes were repeated 3 times and stored in an oven at 60° C. for 24 hours to obtain dried powder particles.

<Experimental Example>

The surface modification of the prepared silica-metal core-shell silica particles was analyzed using a contact angle and IR, and the possibility of application was analyzed by coating metals (Ag and Ni).

1, contact angle and surface energy

The contact angle according to the surface treatment conditions was measured using polar water and the non-polar solvent Diiodomethane (CH ₂ I ₂ ), and the surface energy was calculated using the Girifalco-Good-Fowkes-Young equation based on this.

A picture of the water contact angle of the silica substrate treated with ASP and MPS is shown in FIG. 2 (Table 1), and a _{picture of the CH 2} I ₂ contact angle is shown in FIG. 3 (Table 2).

Measured value of water contact angle on the surface of silica substrate 1 time Episode 2 3rd time 4 times 5 times Average Bare 18.89° 18.41° 18.41° 18.41° 18.24° 18.47° -NH ₂ 50.43° 50.18° 50.18° 51.71° 51.71° 50.84° -SH 60.23° 60.15° 60.15° 61.16° 60.46° 60.43°

Measured value of contact angle of silica substrate surface CH ₂ I ₂ 1 time Episode 2 3rd time 4 times 5 times Average Bare 29.13° 31.73° 31.77° 32.07° 34.43° 31.83° -NH ₂ 27.45° 27.45° 27.45° 25.77° 26.44° 26.91° -SH 28.22° 28.22° 28.22° 27.99° 27.99° 28.13°

Since APS and MPS have a functional group with hydrophilicity, it is expected to show a lower contact angle compared to the existing bare substrate when surface-treated on the substrate. As a result of the contact angle experiment, a relatively high contact angle in the existing bare substrate that was not treated the same as expected, APS or MPS It was confirmed that the contact angle was lowered in the case of the substrate surface-treated with. Each contact angle is measured using a polar solvent (water) and a non-polar solvent (Diiodomethane), and the surface energy is calculated based on this, and the change in surface energy according to the surface treatment of each reactant is quantitatively expressed. Based on the above facts, it was confirmed that APS and MPS exist on the surface of the substrate.

Surface energy calculated through Owens-Wendt method (unit: mJ/m ² ) 1 time Episode 2 3rd time 4 times 5 times Average Bare 72.48 72.20 72.20 72.15 71.86 72.18 -NH ₂ 40.55 40.53 40.53 41.28 41.04 40.79 -SH 41.09 41.08 41.08 41.27 41.29 41.16

For _{the substrate treated with NH 2} self-assembled monolayer (APS), the calculated surface energy was 40.79mJ/m ^2, and the calculated surface energy for the substrate treated with SH self-assembled monolayer (MPS) was 41.16mJ. It was confirmed that the surface was successfully treated with /m2 (Table 3).

2. Whether functional groups are detected

(1) TGA (thermal gravimetric analysis) analysis

The silica particles treated with the ASP and MPS were heated in the range of 25 to 500° C. at 10° C./min to perform TGA analysis, and the results are shown in FIG. 4.

Referring to FIG. 4, it was difficult to obtain significant results due to insufficient weight change in _{the NH 2 and SH samples.} This was because the weight ratio of the reacted coupling agents (ASP and MPS) to the weight of the silica particles was very small, so the weight change could not be confirmed with the TGA scale within the measured temperature range.

(2) Photoelectron spectroscopy (X-ray photoelectron spectroscopy, XPS)

The silica particles treated with the ASP and MPS were confirmed whether or not functional groups were detected using XPS (FIG. 5).

Referring to FIG. 5, _{in the case of a substrate treated with an NH 2 self-assembled monolayer (APS), a peak of -NH 2} was detected at 401.8 eV and 399.4 eV of binding energy, indicating that the surface treatment of the silica particles was successfully performed. I could confirm. In the case of the substrate treated with the SH self-assembled monolayer (MPS), a peak of -SH was detected at a binding energy of 162.8 eV, confirming that the surface modification of the silica particles was successfully performed.

3. Ag coating rate

The present inventors applied the electroless plating metal coating process and analyzed the coating results according to the surface treatment conditions of the silica particles and the type of metal used (Ag). The coating result was magnified at high magnification using a SEM (Scanning electron microscope) to evaluate the particle surface coating rate.

(1) Formation of Silica-Ag core-shell composite structure using _{NH 2 surface-treated silica particles (Fig. 6)}

Referring to the experimental results of FIG. 6, it can be seen that an Ag plating layer having a thicker layer compared to the conventional silica particles was formed. Through this, it was confirmed that high-quality core-shell composite structure particles can be formed through the surface treatment of silica particles. It was confirmed that the change according to the presence or absence of UV/O ₃ washing was insignificant and did not affect the formation of the core-shell composite structure particles, so that the pretreatment process, washing, was not necessary.

(2) Formation of Silica-Ag core-shell composite structure using SH surface-treated silica particles (Fig. 7)

Referring to the experimental results of FIG. 7, it can be seen that an Ag plating layer having a thicker layer compared to the conventional silica particles was formed. Through this, it was confirmed that high-quality core-shell composite structure particles can be formed through the surface treatment of silica particles. It was confirmed that the change according to the presence or absence of UV/O ₃ washing was insignificant and did not affect the formation of the core-shell composite structure particles, so that the pretreatment process, washing, was not necessary.

Claims (8)

1) placing the silica particle powder and the silane coupling agent inside the reaction vessel;
2) maintaining the reaction vessel under vacuum; and
3) A method for surface modification of silica powder using a solvent-free vapor deposition method comprising the step of heat-treating the reaction vessel in a vacuum oven at 100 to 150°C.
The method of claim 1,
The silane coupling agent is 3-aminopropyltriethoxysilane, (3-mercaptopropyl) trimethoxysilane ((3-Mercaptopropyl) trimethoxysilane), n-octyltriethoxysilane (n-octyl -triethoxy-silane), decyltrimethoxysilane, decyltrimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane (N,Nb is (2-hydroxyethyl)-3-aminopropyltriethoxy silane), 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxy-silane, or a combination thereof Method for modifying the surface of silica powder, characterized in that.
The method of claim 1,
The method of modifying the surface of silica powder, characterized in that the heat treatment step in step 3) is 130°C.
The method of claim 1,
Surface modification method of silica powder, characterized in that it further comprises the step of _{UV / O 3} washing after step 3).
The method of claim 1,
The surface modification method of silica powder, characterized in that the water contact angle of the surface-modified silica particles is 45 ~ 65 °.
A method for producing a silica-metal core-shell composite comprising the step of coating a metal on the surface of the silica particles by using an electroless plating method on the silica particles surface-modified by the method of claim 1.
The method of claim 1,
The metals are gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), tungsten (W), titanium (Ti), platinum (Pt), palladium (Pd), tin ( Sn), lead (Pb) and zinc (Zn), characterized in that any one selected from the group consisting of silica-metal core-shell composite manufacturing method.
The silica-metal core-shell prepared by the method of claim 7.

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