WO1997027150A1

WO1997027150A1 - Porous glass coated with an organic polymer and a method of coating porous glass with an organic polymer

Info

Publication number: WO1997027150A1
Application number: PCT/US1997/001596
Authority: WO
Inventors: Tatsuhiro Takahashi
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1996-01-29
Filing date: 1997-01-23
Publication date: 1997-07-31
Also published as: AU2252897A; JPH09208265A

Abstract

This invention presents porous glass coated with an organic polymer that has excellent adhesion and peeling resistance, and a method of coating the glass with the organic polymer. After applying a polymer solution made of the organic polymer and a solvent in which the polymer is soluble to the surface of the porous glass, the product is heated at the melting point or the glass transition point of the polymer or higher.

Description

TITLE

POROUS GLASS COATED WITH AN ORGANIC POLYMER AND A

METHOD OF COAΗNG POROUS GLASS WITH AN ORGANIC POLYMER

BACKGROUND OF THE INVENTION This invention pertains to porous glass coated with an organic polymer and a method of coating porous glass with said organic polymer.

There is porous glass with a fine pore diameter ranging from sub-microns to microns with a composition of Siθ2-B2θ3-Na2θ, Siθ2-A.2θ3-CaO, etc. This type of porous glass has a much finer pore diameter than metals, plastics, or ceramics and is superior in chemical resistance, insulation, etc. Therefore, it is being researched and developed as a material for gas separation and liquid separation, a catalyst support, and a filtration material. Furthermore, it is sometimes used as a biocompatible material (Porous Glass, Kino Zairyo, 7/1995, Vol. 15, No. 7). Phase splitting, the method whereby sand is used as a starting material, etc., are being developed as methods of producing the aforementioned porous glass. Moreover, a method of producing porous glass by the sol-gel method has recently been developed. By means of this method, it is possible to obtain porous glass with a fine pore diameter on a micron level and a narrow pore diameter distribution (Japanese Kokai Patent No. Hei 3(1991)-8729).

However, the aforementioned research and development of porous glass has focused mainly on pore diameter and porosity and there has not been sufficient research of improvement of the other properties (adhesion with another material, etc.) of porous glass, particularly organic polymer coatings for porous glass.

Polymers that have hydrogen bonds, such as polyvinyl alcohol or polyamide, and polymers that have silanol groups (SiOH groups) that react with the Si-OH groups at the glass surface will adhere strongly to glass sheets that are not porous. However, it is extremely difficult to fix a polymer that does not have hydrogen bonds or that cannot bond chemically to a sheet of glass.

Therefore, the purpose of this invention is to solve the aforementioned problems and present a porous glass, which his firmly coated with an organic polymer that could not be firmly applied to glass by conventional methods, and a method of coating porous glass with an organic polymer coating. SUMMARY OF THE INVENTION

In order to solve the aforementioned problems, the porous glass of this invention is characterized by the fact that at least one side is coated with an organic polymer. It is particularly preferred that the organic polymer be applied to the aforementioned glass in the form of an organic polymer solution that consists of the aforementioned organic polymer and a solvent in which the organic polymer is soluble. The glass is then heated at the melting point or glass transition temperature of the polymer or higher.

This invention also presents a method of coating at least one side of porous glass with an organic polymer, which is characterized by the fact that it consists of the process whereby at least one side of a porous glass is coated with an organic polymer solution made of an organic polymer and a solvent in which said organic polymer is soluble and a process whereby the side of the glass that has been coated with the aforementioned organic polymer solution is heat treated at the melting point or glass transition temperature of the aforementioned organic polymer or higher.

DETAILED DESCRIPTION The method of coating a porous glass with an organic polymer of this invention is characterized by the fact that after the polymer solution made of an organic polymer and a solvent in which said polymer is soluble is applied to the surface of a porous glass, this surface is heated treated at the melting point or glass transition temperature of said polymer or higher.

The porous glass used in this invention can be porous glass with a known structure and it can be made by conventional methods. The basic composition of porous glass is Naθ2-B2θ3-Siθ2- Porous glass is made by sintering glass powder, the sol-gel method, phase splitting, etc. Moreover, CaO-Al₂θ3-B₂θ3-Siθ2 porous glass made using sand as the starting material can also be employed. Furthermore, porous glass made by the Coming method by adding a small amount of AI2O3 to 55 to 80 wt% Siθ2, porous glass made by the PPG method using 35 to 50 wt% SiO₂, porous glass made from SiO₂-P2θ₅-Na O, porous glass made from Siθ2-B2θ3-CaO-MgO-Al2θ -Tiθ2, alkali resistant porous glass made of Siθ2ZrO₂-B2θ3-Na₂O-RO (R = Zn or an alkali earth metal), Siθ2-B₂θ3-Na₂O-GeO porous glass, and Na₂O-B2θ3-Ceθ2-Nb₂θ5 porous glass, etc., can also be used in this invention. The polymer to be coated on the glass surface is selected in accordance with the purpose of coating the glass. For instance, when the porous glass is going to be used as a catalyst carrier, a fluorine polymer is employed in order to prevent catalyst oxidation and improve durability. Moreover, if the purpose is to block ultraviolet light or to tint only the surface of the glass, an organic polymer solution to which ultraviolet blocker or paint has been added is applied and then the solvent is removed to firmly deposit the ultraviolet blocker or paint on the glass surface.

The polymer that has been selected is dissolved in a solvent in which it is soluble and applied to porous glass. The solvent can be formic acid when the polymer is polyamide, and even nonpoiar polymers and fluorine polymers can be thoroughly dissolved.

The organic polymer solution made of an organic polymer and a solvent in which said polymer is soluble is applied by conventional methods, such as dipping, spraying, spin coating, etc. The heat treatment temperature after applying the polymer solution is determined based on the polymer that is used. The temperature is the melting point of the polymer or higher when a crystalline polymer is used and the glass-transition temperature or higher when a non- crystalline polymer is used. Heat treatment can be performed by any conventional method, such as in an oven, a vacuum oven, with a hair dryer, etc.

As an example, porous glass coated with a fluorine polymer, such as a copolymer derived from hexafluoropropylene and tetrafluoroethylene, represented by the following general formula (1) (available from DuPont ) is made by applying a polymer solution of said fluorine polymer dissolved in a fluorine solvent, preferably Fluorinate CF-75 made by 3M, to a porous glass and then heat treating the product at 40°C or higher.

-(CF₂CF₂ ) _m- (CF₂-CF) _n-

CF,

( 1 )

Moreover, porous glass coated with another fluorine polymer, such as a copolymer derived from 2,2-bis(trifluoromethyl)-4,5-difluoro-l,3-dioxole and tetrafluoroethylene, represented by the following general formula (2) (such as Teflon® AF1600 or 2400 amorphous fluoropolymers available from DuPont) is made by applying a polymer solution that has been prepared using the aforementioned solvent to porous glass and then heat treating the product coated with Teflon® AF1600 to 160°C or higher and the product coated with Teflon® AF2400 to 240°C or higher.

-(CF₂CF₂ ) _m- (CF-CF_{) rι}- O 0

\ / c

CF₃' CF₃

( 2 )

Another fluoropolymer contemplated as useful in the present invention is a copolymer derived from tetrafluoroethylene and a perfluoroalkylvinyl ether. Furthermore, porous glass coated with polymethyl methacrylate or polystyrene can be obtained by applying a polymer solution that has been prepared using tetrahydrofuran as the solvent and baking the product at a temperature of 100°C or higher. Actual examples of this invention and comparative examples are given below. Very good adhesion of the film and peeling resistance of the film are obtained when compared to conventional coated glass by applying a polymer solution made of an organic polymer and a solvent in which said polymer is soluble to the surface of porous glass and then heat treating the product at the melting point or glass transition temperature of said polymer or higher.

EXAMPLES

The porous glass coated with a polymer was made as follows: That is, a polymer solution made of the organic polymer in Table 1 and a solvent in which said polymer can dissolve was applied to the surface of Baikol made by Corning as the porous glass. In this example, the polymer was heat treated at its melting point or glass-transition temperature or higher. The aforementioned polymer solution was applied by dipping using a film lift made by Rauda. Consequently, the speed at which the porous glass was taken up from the polymer solution was set as shown in Table 3 and the effects of each take-up speed were investigated. In addition, by way of comparison, a comparative glass coated with polymer was made by the same method using slide glass made by Matsunami as the glass.

Furthermore, glass that had been physically roughed with a blaster was also made for comparison. This blaster glass was not transparent.

TABLE 1

Organic Polymer Glass Transition

Solution No. (Content) Solvent Temperature (°C)

1 HFP/TFE copolymer (5 wt %) Fluorinate 20

2 Baiton AHV (5 wt %) Tetrahydroniran -30

3 Teflon® AF1600 (2 wt %) Fluorinate 160

4 Teflon® AF2400 (2 wt %) Fluorinate 240

5 Polystyrene (5 wt %) Tetrahydrofuran 90

6 Polymethyl methacrylate (5 wt %) Tetrahydrofuran 105

The copolymer in solution 1 in Table 1 is made of 43 molar% hexafluoropropylene (HFP) and 57 molar% tetrafluoroethylene TFE (DuPont). The Fluorinate CF-75 is a fluorine solvent made by 3M. Furthermore, the polystyrene and polymethyl methacrylate were PS666 and PMMA 560F Asahi Kasei, respectively. Moreover, the Baiton AHV is an HFP TFE/ vinylidene fluoride (VDF) terpolymer.

Tape peeling tests were performed on the coated glass and then tape peeling tests were performed after making a go-board on the glass.

In the tape peeling tests, Nichiban cellophane tape, 3M Scotch tape 810, and 3M Scotch tape 898 were taped and peeled from the glass 10 times and the peeled state of the coated film was investigated.

Similarly, in the go-board peeling tests, scratches were made from the coated surface down to the glass surface in the form of a go-board using a cutting knife (100 1 mm x 1 mm squares were made). After making the scratches, peeling tests were performed by pulling the film surface with the aforementioned tapes. Each tape was used 10 times.

The results of the aforementioned peeling tests and go-board peeling tests are represented by "O" when there was no peeling, "Δ" when peeling was seen at the corners of some of the 1 mm squares and by "X" 1 or more 1 mm square was completely peeled from the glass. The results are shown in Tables 2 and 3.

Moreover, transparency of the coated glass treated with an "O" when it is good and with an "X" when it is poor.

TABLE 2

Heat

Treatment Take-up

Solution Temperature Speed Tape Go-Board Composition (°C) Glass (mm/min) Peeling Peeling Transparency

150 Slide 30 X - O

150 Slide 100 X - O

150 Slide 300 X - O

150 Baikol 30 0 O O

150 Baikol 100 o O O

150 Baikol 300 O o O

150 Blasted 30 Δ - X

150 Blasted 100 Δ - X

150 Blasted 300 Δ - X

50 Slide 30 X - 0

50 Slide 100 X - 0

50 Slide 300 X - 0

50 Baikol 30 Δ - o

50 Baikol 100 X - 0

50 Baikol 300 X - o

2 150 Slide 30 o Δ 0 2 150 Slide 100 O Δ o

2 150 Baikol 30 O O O

2 150 Baikol 100 O O o

TABLE 3

Heat

Treatment Take-up

Solution Temperature Speed Tape Go-Board Composition CC) Glass (mm/min) Peeling Peeling Transparency

3 300 Slide 30 X - O

3 300 Slide 100 X - O

3 300 Baikol 30 O O O

3 300 Baikol 100 O O O

4 350 Slide 30 X - O

4 350 Slide 100 X - O

4 350 Baikol 30 O o O

4 350 Baikol 100 O O O

5 200 Slide 30 X - O

5 200 Slide 100 X - O

5 200 Baikol 30 O o O

5 200 Baikol 100 O O O

6 200 Slide 30 X - O

6 200 Slide 100 X - O

6 200 Baikol 30 O O O

6 200 Baikol 100 O O O

In Tables 2 and 3, "slide" stands for slide glass, "Baikol" stands for Baikol glass, and "blasted" stands for blaster slide glass.

As is clear from Tables 2 and 3, the porous glass coated with a polymer by the method of this invention does not lose its transparency and has excellent peeling resistance when compared to conventional glass.

Claims

WHAT IS CLAIMED IS:

1. A composition, comprising: a porous glass having at least one side coated with an organic polymer.

2. The composition of Claim 1 wherein the organic polymer is a fluoropolymer.

3. The composition of Claim 2 wherein the fluoropolymer is a copolymer derived from hexafluoropropylene and tetrafluoroethylene, a copolymer derived from 2,2-bis(trifluoromethyl)-4,5-difluoro-l,3-dioxole and tetrafluoroethylene, or a copolymer derived from tetrafluoroethylene and a perfluoroalkylvinyl ether.

4. A method of preparing a composition comprising a porous glass having at least one side coated with an organic polymer, comprising the steps of: applying an organic polymer solution comprising an organic polymer and a solvent in which the organic polymer is soluble to at least one side of a porous glass; and heat treating the side of the porous glass having the solution applied thereto at a temperature that equals or is higher than the melting point or glass transition temperature of the organic polymer.

5. The method of Claim 4 wherein the organic polymer is a fluoropolymer.

6. The method of Claim 5 wherein the fluoropolymer is a copolymer derived from hexafluoropropylene and tetrafluoroethylene, or a copolymer derived from 2,2-bis(trifluoromethyl)-4,5-difluoro-l,3-dioxole and tetrafluoroethylene, or a copolymer derived from tetrafluoroethylene and a perfluoroalkylvinyl ether.

7. The method of Claim 5 wherein the solvent is fluorinated.