# US 6,348,122 B1 · Fire retarding polypropylene composition

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- Number: US 6,348,122 B1
- Document ID: US6348122B1
- Status: Granted
- Kind: B1
- Application number: 09/004,374
- Filed: 1998-01-08
- Granted: 2002-02-19
- Earliest claimed: 1998-01-08
- Assignees: Compression Polymers Group
- Inventors: Jerry Wagner
- Web page: https://patentgrep.com/patent/US6348122B1

## CPC

- C08K 9/04: Ingredients treated with organic substances {(treated with macromolecular compounds C08K9/08)}
- C08K 2003/2217: {of magnesium}
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

A fire retarding polypropylene composition comprising a copolymer of polypropylene and an ethylene/propylene rubber, and at least about 50% by weight but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface active agent, the magnesium hydroxide having (i) a strain in the <101> direction of not more than 3.0×10−3, (ii) a crystallite size in the <101> direction of more than 800 Å, and (iii) a specific surface area, determined by the BET method, of less than 20 mg2/g. The composition can be used in a fire retarding semiconductor apparatus which passes the FMRC Clean Room Materials Flammability Test Protocol.

## Claims

### Claim 1

A method of making a clean room surface component comprised of composition, wherein said composition comprises:
(a) a copolymer polypropylene resin in which ethylene/propylene rubber has been grafted onto the polypropylene chains; and
(b) at least about 50% but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface agent,
wherein said method includes the steps of:
(a) forming pieces from said composition, said pieces being adapted to form said clean room surface component; and
(b) bonding said pieces using thermoplastic welding to make a semiconductor clean room component.

### Claim 2

A clean room component, said clean room component comprising a polymer and magnesium hydroxide composition, the composition comprising a copolymer polypropylene resin in which ethylene-propylene rubber has been grafted onto the polypropylene chains, and at least about 50% but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface active agent, the magnesium hydroxide having:
(i) a strain in the <101> direction of not more than 3.0×10−3,
(ii) a crystallite size in the <101> direction of more than 800 Å, and
(iii) a specific surface area, determined by the BET method, of less than 20 mg2/g; said composition being adapted to meet FMRC standards for use in a clean room.

### Claim 3 (depends on 2)

The component of claim 2 wherein said copolymer contains between about 80% and about 85% polypropylene and between about 15% and about 20% ethylene/propylene rubber.

### Claim 4 (depends on 2)

The component of claim 2 wherein the melt flow index of said copolymer is less than about 1 gram per 10 minute interval.

### Claim 5 (depends on 2)

The component of claim 2 wherein said copolymer is halogen-free.

### Claim 6 (depends on 2)

The component of claim 2 having a Young's modulus of at least about 1.0 ft-lbs. psi.

### Claim 7

A method for producing a fire retarding clean room component, said method comprising the steps of:
(a) mixing a copolymer polypropylene resin in which ethylene/propylene rubber has been grafted onto the polypropylene chain with at least about 50% but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface active agent, the magnesium hydroxide having:
(i) a strain in the <101> direction of not more than 3.0×10−3,
(ii) a crystallite size in the <101> direction of more than 800 Å, and
(iii) a specific surface area, determined by the BET method, of less than 20 mg2/g at a temperature above a melting point of the copolymer to form a blend; and,
(b) forming said blend into said clean room component.

### Claim 8 (depends on 7)

The method of claim 7 said forming comprising processing said blend into pellets and cooling the pellets.

### Claim 9 (depends on 7)

The method of claim 7 said forming comprising processing said blend by extrusion, injection molding, or compression molding into said clean room component.

### Claim 10

A compression molded clean room surface component comprised of a fire retarding polypropylene composition, wherein the composition comprises:
(a) a copolymer polypropylene resin in which ethylene/propylene rubber has been grafted onto the polypropylene chains; and
(b) at least about 50% but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface agent.

### Claim 11

A method of making a clean room surface component comprising the steps of:
(a) providing a composition including a copolymer polypropylene resin in which ethylene/propylene rubber has been grafted onto the polypropylene chains; and at least about 50% but not greater than 60% by weight of a magnesium hydroxide coated with an anionic surface agent, the magnesium hydroxide having:
(i) a strain in the <101> direction of not more than 3.0×10−3,
(ii) a crystallite size in the <101> direction of more than 800 Å, and
(iii) a specific surface area, determined by the BET method, of less than 20 mg2/g; and
(b) compression molding said composition to make a clean room surface component.