WO1994016015A1 - Moulding compositions containing nylon - Google Patents

Moulding compositions containing nylon Download PDF

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Publication number
WO1994016015A1
WO1994016015A1 PCT/GB1993/002485 GB9302485W WO9416015A1 WO 1994016015 A1 WO1994016015 A1 WO 1994016015A1 GB 9302485 W GB9302485 W GB 9302485W WO 9416015 A1 WO9416015 A1 WO 9416015A1
Authority
WO
WIPO (PCT)
Prior art keywords
moulding
nylon
composition
magnesium hydroxide
caprolactam
Prior art date
Application number
PCT/GB1993/002485
Other languages
French (fr)
Inventor
Richard Stuart Williams
Original Assignee
T&N Technology Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by T&N Technology Limited filed Critical T&N Technology Limited
Priority to EP94900968A priority Critical patent/EP0678113A1/en
Publication of WO1994016015A1 publication Critical patent/WO1994016015A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/34—Heterocyclic compounds having nitrogen in the ring
    • C08K5/3412—Heterocyclic compounds having nitrogen in the ring having one nitrogen atom in the ring
    • C08K5/3432—Six-membered rings

Definitions

  • This invention is concerned with moulding compositions which contain nylon, e.g. nylon 6 or nylon 66, and is especially concerned with such compositions which contain magnesium hydroxide as a flame retardant.
  • Nylon is widely used for moulding components.
  • Nylon 6 is produced from caprolactam with the polymerised product containing about 90% of nylon and about 10% of low molecular weight material such as the monomer. Before such a polymerised product is used for moulding, it is washed to remove the monomer. The unwashed product is known as "unwashed nylon” or as "high monomer nylon”. In some moulding applications, it is desirable that the moulded component exhibits flame retardant characteristics. Such applications include electrical lamp-holders, and switch housings.
  • Magnesium hydroxide is a flame retardant which has been suggested for use with nylon. This material, when subjected to a flame, decomposes endothermically with the liberation of water. Nylon containing magnesium hydroxide has been found to be difficult to mould because of its high melt viscosity and, furthermore, it is found that the mouldings have obvious surface defects which render them unacceptable commercially. Such surface defects manifest themselves by the appearance of white patches on the surface of the moulding. Various attempts have been made to overcome this problem but without achieving complete success. The most successful previous attempt known to the applicants involves the addition of organic sulphonamide (see GB 2,237,573A) but even this has not achieved total success.
  • the invention provides a moulding composition containing nylon and magnesium hydroxide as a flame- retardant, characterised in that the composition also contains sufficient caprolacta to reduce the formation of surface defects in the moulding.
  • Mouldings made from a composition according to the invention are found to be substantially free of surface defects. Furthermore, such compositions are also found to be much easier to mould.
  • the caprolactam can be provided by the use of unwashed nylon in the composition, possibly with the addition of further caprolactam. Alternatively, if the nylon has been washed, the caprolactam is added.
  • the caprolactam may be present in up to 10% by weight e.g. between 1% and 5%.
  • a composition according to the invention may contain up to 60% by weight of magnesium hydroxide e.g. between 45% and 65%. Alternatively, if a lower flame retardant standard is acceptable, the composition may contain 20-45% by weight of magnesium hydroxide.
  • the composition may also contain reinforcing fibres, e.g. glass fibres, which may be present in up to 35% by weight depending on the amount of magnesium hydroxide which is present.
  • the second illustrative composition contained 34.98% by weight of the same unwashed nylon as the first illustrative composition. It also contained 0.30% of calcium stearate, 14.75% of glass fibres, and 49.97% of magnesium hydroxide. It was mixed, compounded and injection moulded into test rods in the same way as the first illustrative composition. The mouldability and surface finish were substantially the same as for the first illustrative composition.
  • the second illustrative composition was moulded into lamp-holders and the surface finish was found to be excellent. These lamp-holders also passed the Underwriters Laboratory Inc. flammability test (UL 94 test) with a rating of Vo at 1.5mm and had good impact strength.
  • UL 94 test Underwriters Laboratory Inc. flammability test
  • a moulding composition falling outside the invention was mixed, compounded and injection moulded into test rods under the same conditions as the first and the second illustrative compositions.
  • This composition contained 35.88% by weight of washed nylon 6, 0.35% calcium stearate, 10% glass fibre and 53.82% magnesium hydroxide. The material was difficult to extrude as strand breakage occurred, and was difficult to injection mould taking 10% longer.
  • the test bar surfaces were covered in white marks.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

A moulding composition containing nylon and magnesium hydroxide which acts as a flame-retardant. In order to reduce surface defects in the moulding, the composition also contains caprolactam.

Description

MOULDING COMPOSITIONS CONTAINING NYLON
This invention is concerned with moulding compositions which contain nylon, e.g. nylon 6 or nylon 66, and is especially concerned with such compositions which contain magnesium hydroxide as a flame retardant.
Nylon is widely used for moulding components. Nylon 6 is produced from caprolactam with the polymerised product containing about 90% of nylon and about 10% of low molecular weight material such as the monomer. Before such a polymerised product is used for moulding, it is washed to remove the monomer. The unwashed product is known as "unwashed nylon" or as "high monomer nylon". In some moulding applications, it is desirable that the moulded component exhibits flame retardant characteristics. Such applications include electrical lamp-holders, and switch housings.
Magnesium hydroxide is a flame retardant which has been suggested for use with nylon. This material, when subjected to a flame, decomposes endothermically with the liberation of water. Nylon containing magnesium hydroxide has been found to be difficult to mould because of its high melt viscosity and, furthermore, it is found that the mouldings have obvious surface defects which render them unacceptable commercially. Such surface defects manifest themselves by the appearance of white patches on the surface of the moulding. Various attempts have been made to overcome this problem but without achieving complete success. The most successful previous attempt known to the applicants involves the addition of organic sulphonamide (see GB 2,237,573A) but even this has not achieved total success.
It is an object of the present invention to provide a nylon moulding composition containing magnesium hydroxide as a flame retardant which produces mouldings which are substantially free of surface defects of the type referred to.
The invention provides a moulding composition containing nylon and magnesium hydroxide as a flame- retardant, characterised in that the composition also contains sufficient caprolacta to reduce the formation of surface defects in the moulding.
Mouldings made from a composition according to the invention are found to be substantially free of surface defects. Furthermore, such compositions are also found to be much easier to mould.
As nylon is prepared from caprolactam, the caprolactam can be provided by the use of unwashed nylon in the composition, possibly with the addition of further caprolactam. Alternatively, if the nylon has been washed, the caprolactam is added. The caprolactam may be present in up to 10% by weight e.g. between 1% and 5%.
A composition according to the invention may contain up to 60% by weight of magnesium hydroxide e.g. between 45% and 65%. Alternatively, if a lower flame retardant standard is acceptable, the composition may contain 20-45% by weight of magnesium hydroxide. The composition may also contain reinforcing fibres, e.g. glass fibres, which may be present in up to 35% by weight depending on the amount of magnesium hydroxide which is present. There now follows a detailed description of two moulding compositions which are illustrative of the invention.
The first illustrative composition contained 37.01% by weight of unwashed nylon which contained about 10% of caprolactam and about 2.5% of water. The composition also contained 0.30% by weight of calcium stearate (as a mould lubricate), 9.82% of glass fibre as a reinforcement, and 52.87% of magnesium hydroxide as a flame retardant. The constituents were mixed together in a blender and fed into a compounder through the main hopper. The compounder was a Baker Perkins 2030 twin screw extruder operating with a barrel temperature of 260°C (feed region at 180°C) , a feed rate of 9 to 12 kg/hour, and a screw speed of 250 RPM. The material was found to be easy to extrude and the extruded strand did not break.
Test rods were injection moulded from the first illustrative moulding composition using a Battenfeld BA 750 CD Plus injection moulding machine. The barrel temperature was 280°C and the mould temperature 115°C. The test rods were easy to mould and were found to have a very good surface finish with hardly any defects.
The second illustrative composition contained 34.98% by weight of the same unwashed nylon as the first illustrative composition. It also contained 0.30% of calcium stearate, 14.75% of glass fibres, and 49.97% of magnesium hydroxide. It was mixed, compounded and injection moulded into test rods in the same way as the first illustrative composition. The mouldability and surface finish were substantially the same as for the first illustrative composition.
The second illustrative composition was moulded into lamp-holders and the surface finish was found to be excellent. These lamp-holders also passed the Underwriters Laboratory Inc. flammability test (UL 94 test) with a rating of Vo at 1.5mm and had good impact strength.
For comparison purposes, a moulding composition falling outside the invention was mixed, compounded and injection moulded into test rods under the same conditions as the first and the second illustrative compositions. This composition contained 35.88% by weight of washed nylon 6, 0.35% calcium stearate, 10% glass fibre and 53.82% magnesium hydroxide. The material was difficult to extrude as strand breakage occurred, and was difficult to injection mould taking 10% longer. The test bar surfaces were covered in white marks.

Claims

A moulding composition containing nylon and magnesium hydroxide as a flame-retardant, characterised in that the composition also contains sufficient caprolactam to reduce the formation of surface defects in the moulding.
A moulding composition according to Claim 1, characterised in that the caprolactam is provided by the use of unwashed nylon.
A moulding composition according to either one of Claims 1 and 2, characterised in that the caprolactam is present in up to 10% by weight.
A moulding composition according to any one of Claims 1 to 3, characterised in that the composition contains between 45% and 65% by weight of magnesium hydroxide.
A moulding composition according to any one of Claims 1 to 4, characterised in that the composition also contains reinforcing fibres.
PCT/GB1993/002485 1993-01-08 1993-12-02 Moulding compositions containing nylon WO1994016015A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP94900968A EP0678113A1 (en) 1993-01-08 1993-12-02 Moulding compositions containing nylon

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9300308.5 1993-01-08
GB9300308A GB2274109B (en) 1993-01-08 1993-01-08 Moulding compositions containing nylon

Publications (1)

Publication Number Publication Date
WO1994016015A1 true WO1994016015A1 (en) 1994-07-21

Family

ID=10728464

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/002485 WO1994016015A1 (en) 1993-01-08 1993-12-02 Moulding compositions containing nylon

Country Status (3)

Country Link
EP (1) EP0678113A1 (en)
GB (1) GB2274109B (en)
WO (1) WO1994016015A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997010303A1 (en) * 1995-09-13 1997-03-20 Du Pont Thermoplastic resin composition

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7258920B2 (en) * 2003-11-18 2007-08-21 Honeywell International Inc. Multiphase fiber materials and compositions, methods of manufacture and uses thereof
US7790789B2 (en) * 2003-11-18 2010-09-07 Honeywell International, Inc. Pre-fiber gel materials and compositions, methods of manufacture and uses thereof

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH405706A (en) * 1961-09-27 1966-01-15 Inventa Ag Process for the production of uniformly fine crystalline polyamide moldings
EP0576951A1 (en) * 1992-07-03 1994-01-05 Bayer Ag Flame retardant polyamide moulding compositions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH405706A (en) * 1961-09-27 1966-01-15 Inventa Ag Process for the production of uniformly fine crystalline polyamide moldings
EP0576951A1 (en) * 1992-07-03 1994-01-05 Bayer Ag Flame retardant polyamide moulding compositions

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997010303A1 (en) * 1995-09-13 1997-03-20 Du Pont Thermoplastic resin composition

Also Published As

Publication number Publication date
GB2274109A (en) 1994-07-13
GB2274109B (en) 1996-07-03
EP0678113A1 (en) 1995-10-25
GB9300308D0 (en) 1993-03-03

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