GB2296245A - Static dissipative plastics materials - Google Patents
Static dissipative plastics materials Download PDFInfo
- Publication number
- GB2296245A GB2296245A GB9524746A GB9524746A GB2296245A GB 2296245 A GB2296245 A GB 2296245A GB 9524746 A GB9524746 A GB 9524746A GB 9524746 A GB9524746 A GB 9524746A GB 2296245 A GB2296245 A GB 2296245A
- Authority
- GB
- United Kingdom
- Prior art keywords
- static dissipative
- fibres
- weight
- polymer
- electrically conductive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/16—Anti-static materials
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A static dissipative plastics material comprises a polymer blend of a major proportion of a base thermoplastics material and a minor proportion of a functional static dissipative polymer. The material also comprises electrically conductive fibres, eg of steel, distributed in the polymer blend without forming an electrically conductive network therein.
Description
8TATIC DISSIPATIVE PLASTICS MATERIALS
This invention is concerned with a static dissipative plastics materials which can be used, for example, for moulding containers, eg by injection moulding.
Static dissipative (or antistatic) plastics materials are used for moulding containers which must have a static electricity dissipating ability. Such containers may, for example, contain electronic equipment which can be affected by static electricity. The ability to dissipate static electricity is measured by the material's resistivity in
Ohms square. In order to be acceptable, a material must have the necessary properties such as mouldability and strength to form an acceptable container and must have a resistivity in the range 106 to 1010 Ohms square and must be able to dissipate away an induced charge of 5000 volts within 2 seconds.Thermoplastics materials, such as polypropylene and acrylonitrile butadiene styrene (ABS), can be brought into this resistivity range by filling them with carbon black but this has the disadvantage that the material is inherently black in colour (indeed it leaves black marks behind) so that aesthetically pleasing colours or colour coded containers cannot be produced from such materials. Furthermore, the process is difficult to control at the curve of resistivity against carbon black loading is steep.
A static dissipative plastics material which can be coloured with pigments in the usual way can be produced by forming a polymer blend of a major proportion of a base thermoplastics material with a minor proportion of a functional static dissipative polymer. Such static dissipative polymers are available commercially, eg the polymer sold under the Trade Mark "Statrite" by B. F.
Goodrich. It is believed that this polymer is a chain extended polyoxirane. Further information about static dissipative polymers can be found in EP 0 287 092 B1. The base thermoplastics material gives the necessary strength etc. to the material while the functional static dissipative polymer gives the required resistivity. For example, one such polymer blend consists of about 80% by weight of ABS, and about 20% by weight of Statrite.
However, although such materials are colourable, they only achieve a resistivity of about 1010 Ohms square and cannot be used for the 106 to 109 part of the required resistivity range.
Accordingly, it is an object of the present invention to provide a static dissipative plastics material which can be coloured with pigments in the usual way and can give a resistivity in the range 106 to 109 Ohms square.
The invention provides a static dissipative plastics material which comprises a polymer blend of a major proportion of a base thermoplastics material and a minor proportion of a functional static dissipative polymer, wherein the material also comprises electrically conductive fibres distributed in the polymer blend without forming an electrically conductive network therein.
A material according to the invention can be coloured by pigments in the usual way and can easily achieve a resistivity of 108 Ohms square or a factor of 10 either way.
In order to avoid forming an electrically conductive network, the proportion of fibres in the material has to be low; preferably the fibres form less than 5% by weight of the material, although the proportion depends on the density of the material from which the fibres are formed.
For steel fibres a proportion of less than 4% by weight, eg 3%, is advantageous.
Preferably, in order to avoid forming an electrically conductive network, short fibres are used. For example, the fibres may be less than 8 mm in length, preferably less than 6 mm.
The fibres may be made of any suitable electrically conductive material, for example steel, copper, carbon etc.
A suitable diameter for the fibres is 8 to 12 microns, eg 11 microns.
The base thermoplastics material may be ABS, polypropylene or any other suitable polymeric material or copolymer or blend of polymers and/or copolymers. The base thermoplastics material may form at least 68% by weight of the material.
The functional static dissipative polymer may be
Statrite and may form up to 29% by weight of the material.
There now follows a detailed description of a material and is method of formation which are illustrative of the invention.
In the illustrative method, ABS was used as an engineering plastics material forming the base polymer,
Statrite was used as the functional static dissipative polymer, and steel fibres were used as the electrically conductive fibres. The fibres were 11 microns in diameter and were chopped to a length of about 6 mm.
In the illustrative method, a blend of 80% by weight of ABS and 20% by weight of Statrite was formed. Also, a master batch of 75% by weight of the steel fibres and 25% by weight of an alkyd binder was formed. Sufficient of the master batch was mixed into the blend to form 4% by weight of the combined total. The illustrative material so formed comprised 3% by weight of steel fibres, 76.8% by weight of
ABS, and 19.2% by weight of Statrite, the remainder being the binder.
The illustrative material could easily be coloured by pigments. It was injection moulded into containers which were satisfactory in their physical properties, having a resistivity of 108 Ohms square.
Claims (7)
1 A static dissipative plastics material which comprises
a polymer blend of a major proportion of a base
thermoplastics material and a minor proportion of a
functional static dissipative polymer, wherein the
material also comprises electrically conductive fibres
distributed in the polymer blend without forming an
electrically conductive network therein.
2 A material according to claim 1, wherein the fibres
form less than 5% by weight of the material.
3 A material according to either one of claims 1 and 2,
wherein the fibres are less than 8 mm in length.
4 A material according to any one of claims 1 to 3,
wherein the fibres are made of steel.
5 A material according to any one of claims 1 to 4,
wherein the base thermoplastics material forms at
least 68% by weight of the material.
6 A material according to any one of claims 1 to 5,
wherein the functional static dissipative polymer
forms up to 29% by weight of the material.
7 A static dissipative plastics material substantially
as hereinbefore described with reference to the
illustrative example.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9426073.4A GB9426073D0 (en) | 1994-12-23 | 1994-12-23 | Static dissipative plastics materials |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9524746D0 GB9524746D0 (en) | 1996-02-07 |
| GB2296245A true GB2296245A (en) | 1996-06-26 |
| GB2296245B GB2296245B (en) | 1998-06-10 |
Family
ID=10766486
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9426073.4A Pending GB9426073D0 (en) | 1994-12-23 | 1994-12-23 | Static dissipative plastics materials |
| GB9524746A Expired - Fee Related GB2296245B (en) | 1994-12-23 | 1995-12-04 | Static dissipative plastics materials |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9426073.4A Pending GB9426073D0 (en) | 1994-12-23 | 1994-12-23 | Static dissipative plastics materials |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9426073D0 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0112197A1 (en) * | 1982-11-05 | 1984-06-27 | General Electric Company | Synergistic effect of metal flake and metal or metal coated fiber on EMI shielding effectiveness of thermoplastics |
| EP0185783A1 (en) * | 1984-12-20 | 1986-07-02 | General Electric Company | Improved EMI shielding effecttiveness of thermoplastics |
| WO1989000098A2 (en) * | 1987-07-06 | 1989-01-12 | Banks Mark T | Thermoplastic composite pellets, method of making them and conductive molded articles produced therefrom |
| EP0506386A2 (en) * | 1991-03-29 | 1992-09-30 | Sumitomo Chemical Company Limited | Antistatic resin compositions |
| WO1994023433A1 (en) * | 1993-03-31 | 1994-10-13 | Hyperion Catalysis International, Inc. | High strength conductive polymers |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1318740C (en) * | 1987-04-17 | 1993-06-01 | Simon Hsiao-Pao Yu | Copolymers of ethylene oxide as antistatic additives |
-
1994
- 1994-12-23 GB GBGB9426073.4A patent/GB9426073D0/en active Pending
-
1995
- 1995-12-04 GB GB9524746A patent/GB2296245B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0112197A1 (en) * | 1982-11-05 | 1984-06-27 | General Electric Company | Synergistic effect of metal flake and metal or metal coated fiber on EMI shielding effectiveness of thermoplastics |
| EP0185783A1 (en) * | 1984-12-20 | 1986-07-02 | General Electric Company | Improved EMI shielding effecttiveness of thermoplastics |
| WO1989000098A2 (en) * | 1987-07-06 | 1989-01-12 | Banks Mark T | Thermoplastic composite pellets, method of making them and conductive molded articles produced therefrom |
| EP0506386A2 (en) * | 1991-03-29 | 1992-09-30 | Sumitomo Chemical Company Limited | Antistatic resin compositions |
| WO1994023433A1 (en) * | 1993-03-31 | 1994-10-13 | Hyperion Catalysis International, Inc. | High strength conductive polymers |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9524746D0 (en) | 1996-02-07 |
| GB9426073D0 (en) | 1995-02-22 |
| GB2296245B (en) | 1998-06-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20071204 |