Apparatus and process for plasma treatment of particulate matter

• US 6,428,861 B2
• Filed: 06/12/2001
• Issued: 08/06/2002
• Est. Priority Date: 06/13/2000
• Status: Expired due to Fees

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: France, Paul Amaat, Datta, Saswati, Radomyselski, Arseni V.
• Primary Examiner(s): Seidleck, James
• Assistant Examiner(s): Asinovsky, Olga
• Application Number:
  US09/879,593
• Publication Number:
  US 20010050056A1
• Time in Patent Office: 420 Days
• Field of Search: 427/488, 118/716, 118/723.R
• US Class Current: 427/488
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4533 plasma assisted
• CPC Class Codes: C04B 41/4584 Coating or impregnating of particulate or fibrous ceramic material C04B20/10, C04B35/628 take precedence
• CPC Class Codes: C04B 41/48 Macromolecular compounds
• CPC Class Codes: C04B 41/81 Coating or impregnation
• CPC Class Codes: C23C 16/4417 Methods specially adapted for coating powder
• CPC Class Codes: C23C 16/50 using electric discharges generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34

Abstract

A process for plasma treatment of particulate matter, and more particularly, an apparatus for plasma induced graft polymerization of particulate matter in a continuous or semi-continuous manner, and a process for plasma induced graft polymerization of particulate matter in a continuous or semi-continuous manner is provided.

Claims

1. An apparatus for plasma induced graft polymerization of particulate matter in a continuous or semi-continuous manner, comprising:

a vacuum processing chamber comprising a first hopper section, a longitudinal middle section, and a second hopper section;

said first hopper section having an inlet, a closed end, a longitudinal middle portion and an open end, said first hopper section being oriented along a first longitudinal axis, and said inlet of said first hopper section being removably connectable to a particulate matter feed valve;

said longitudinal middle section having a first open end, a longitudinal middle portion, and a second open end, said longitudinal middle section being oriented along said first longitudinal axis;

said vacuum processing chamber being rotatable at the mid-point of said longitudinal middle section through at least 180 degrees about a second longitudinal axis, said second longitudinal axis being perpendicular to said first longitudinal axis;

said second hopper section having an inlet, a closed end, a longitudinal middle portion and an open end, said second hopper section being oriented along said first longitudinal axis, and said inlet of said second hopper section being removably connectable to a polymerizable liquid monomer feed valve;

said open end of said first hopper section being connected with said first open end of said longitudinal middle section through a first valve;

said open end of said second hopper section being connected with said second open end of said longitudinal middle section through a second valve;

said particulate matter feed valve being removably connected to said inlet of said first hopper section and said polymerizable liquid monomer feed valve being removably connected to said inlet of said second hopper section when said vacuum processing chamber is at a rotational position “

a”

, and said particulate matter feed valve being removably connected to said inlet of said second hopper section and said polymerizable liquid monomer feed valve being removably connected to said inlet of said first hopper section when said vacuum processing chamber is at a rotational position “

b”

, wherein said rotational position “

b”

is 180 degrees with respect to said rotational position “

a”

;

said first hopper section being adapted to deliver untreated and plasma treated particulate matter to said longitudinal middle section and said second hopper section being adapted to receive one or more of plasma treated particulate matter from said longitudinal middle section and said polymerizable liquid monomer when said vacuum processing chamber is at rotational position “

a”

;

said second hopper section being adapted to deliver untreated and plasma treated particulate matter to said longitudinal middle section and said first hopper section being adapted to receive one or more of said plasma treated particulate matter from said longitudinal middle section and said polymerizable liquid monomer when said vacuum processing chamber is at rotational position “

b”

;

said longitudinal middle section being connected to a vacuum generation pump means for maintaining a vacuum or near-atmospheric pressure therein; and

said longitudinal middle section having plasma generating electrodes disposed therein for generating a plasma glow discharge using a non-polymerizable plasma gas for exposing said particulate matter to said plasma glow discharge, as said particulate matter descends through said longitudinal middle section under gravity.

2. The apparatus according to claim 1, wherein said longitudinal middle section is connected to pressure sensing means for measuring the pressure therein.

3. The apparatus according to claim 1, wherein said longitudinal middle section is connected to an optical emission spectrometer means for plasma diagnostics.

4. The apparatus according to claim 1, wherein said longitudinal middle section is connected to a langmuir probe means for plasma diagnostics.

5. The apparatus according to claim 1, wherein said longitudinal middle section is connected to a mass spectrometer means for plasma diagnostics.

6. The apparatus according to claim 1, wherein said vacuum generation pump means is adapted to produce a vacuum of at least about 500 mTorr.

7. A process for plasma induced graft polymerization of particulate matter in a continuous or semi-continuous manner, comprising the steps of:

(a) providing a vacuum processing chamber comprising;

a vacuum processing chamber comprising a first hopper section, a longitudinal middle section, and a second hopper section;

said first hopper section having an inlet, a closed end, a longitudinal middle portion and an open end, said first hopper section being oriented along a first longitudinal axis, and said inlet of said first hopper section being removably connectable to a particulate matter feed valve;

said longitudinal middle section having a first open end, a longitudinal middle portion, and a second open end, said longitudinal middle section being oriented along said first longitudinal axis;

said vacuum processing chamber being rotatable at the mid-point of said longitudinal middle section through at least 180 degrees about a second longitudinal axis, said second longitudinal axis being perpendicular to said first longitudinal axis;

said second hopper section having an inlet, a closed end, a longitudinal middle portion and an open end, said second hopper section being oriented along said first longitudinal axis, and said inlet of said second hopper section being removably connectable to a polymerizable liquid monomer feed valve;

said open end of said first hopper section being connected with said first open end of said longitudinal middle section through a first valve;

said open end of said second hopper section being connected with said second open end of said longitudinal middle section through a second valve;

said particulate matter feed valve being removably connected to said inlet of said first hopper section and said polymerizable liquid monomer feed valve being removably connected to said inlet of said second hopper section when said vacuum processing chamber is at a rotational position “

a”

, and said particulate matter feed valve being removably connected to said inlet of said second hopper section and said polymerizable liquid monomer feed valve being removably connected to said inlet of said first hopper section when said vacuum processing chamber is at a rotational position “

b”

, wherein said rotational position “

b”

is 180 degrees with respect to said rotational position “

a”

;

(b) rotating said vacuum processing chamber about said second longitudinal axis such that said vacuum processing chamber is at a rotational position “

a”

;

(c) providing particulate matter into said first hopper section through said particulate matter feed valve;

(d) providing a vacuum of at least 500 mTorr in said longitudinal middle section;

(e) creating a plasma glow discharge in said longitudinal middle portion by said non-polymerizable gas and forming a plasma zone;

(f) dropping said particulate matter from one of said first hopper section and said second hopper section into said plasma zone in said longitudinal middle section;

(g) treating said particulate matter in said plasma zone as said particulate matter descends through said longitudinal middle section;

(h) collecting said plasma treated particulate matter in one of said first hopper section and said second hopper section;

(i) rotating said vacuum processing chamber about said second longitudinal axis such that said vacuum processing chamber is at a rotational position “

b”

;

(j) repeating steps (f), (g), (h) and (i) for a number of times sufficient to obtain a total residence time in a range of from about 0.001 seconds to 60 seconds;

(k) providing said polymerizable liquid monomer into one of said first hopper section and said second hopper section, through said polymerizable liquid monomer valve; and

(l) exposing treated particulate matter to said polymerizable liquid monomer.

8. The process according to claim 7, wherein said residence time is in a range of from about 0.5 seconds to about 60 seconds.

9. The process according to claim 7, including providing a vacuum of at least 20 mTorr in said longitudinal middle section.

10. The process according to claim 7, wherein the consumption of said non-polymerizable gas is in a range from about 1 sccm to about 1000 sccm.

11. The process according to claim 7, wherein the non-polymerizable gas is selected from the group consisting of helium, argon, oxygen, nitrogen, air, hydrogen, ammonium, fluorocarbon, and mixtures thereof.

12. The process according to claim 7, wherein said polymerizable liquid monomer is vaporized to form a non-polymerizable monomer vapor prior to exposing treated particulate matter to said polymerizable liquid monomer.

13. The process according to claim 7, wherein said plasma glow discharge is generated by using radio frequency, microwave power, or a combination thereof.

14. The process according to claim 7, wherein said polymerizable liquid monomer is selected from the group consisting of acrylic and methacrylic acid of the general formula H₂C═

C(R₂)—

C(O)OH, acrylates and methacrylates of the general formula H₂C═

C(R₂)—

C(O)OR₃, acrylamides and methacrylamides of the general formula (R₂)(R₂)C═

C(R₂)—

C(O)NHR₃, maleic and fumaric acid of the general formula HO(O)C—

C(R₂)═

C(R₂)—

C(O)OH, maleates and fumarates of the general formula R₃O(O)C—

C(R₂)═

C(R₂)C(O)OR₃, vinyl ethers of the general formula (R₂)(R₂)C═

C(R₂)—

O—

R₃, N-vinyl-2-pyrollidone of the formula (R₂)(R₂)C═

C(R₂)—

NCH₂—

CH₂—

CH₂—

C(O), vinyl acetate of the general formula (R₂)(R₂)C═

C(R₂)—

OC(O)CH₃, and aliphatic vinyl compounds of the general formula R₂CH═

CHR₃, and mixtures thereof;

where each R₂ is independently hydrogen or C₁-C₁₀ alkyl, and each R₃ is independently an aliphatic hydrocarbon group of up to about 10 carbon atoms that is unsubstituted or substituted by one or more of carboxy, hydroxy, amino, or a (poly)ethylene oxide group optionally substituted by one or more sulfate, phosphate, or sulfonate groups, or mixtures of such groups.

15. The process according to claim 7, wherein said polymerizable liquid monomer is selected from the group consisting of fluoro-mono and polyacrylate, fluoroolefin, fluorostyrene, fluoroalkylene oxide, fluorinated vinyl alkyl ether monomers, or the copolymers thereof with suitable comonomers, wherein the comonomers are fluorinated or unfluorinated.

16. The process according to claim 7, wherein said plasma glow discharge is generated in a modulated manner, including subsequent time-on and time-off intervals.

17. The process according to claim 7, wherein said polymerizable liquid monomer is provided into the longitudinal middle section.