GB2038348A

GB2038348A - Phenolic materials

Info

Publication number: GB2038348A
Application number: GB7942628A
Authority: GB
Original assignee: DESAI POLYMER DEV
Current assignee: DESAI POLYMER DEV
Priority date: 1978-12-12
Filing date: 1979-12-11
Publication date: 1980-07-23

Abstract

A phenolic material which may be used as a substitute for certain types of asbestos, comprises the product obtained by polymerizing a phenolic resin alone or in admixture with at least one other resin, e.g. an epoxy resin, in the presence of a catalyst, a reinforcing material, e.g. glass fibre or carbon fibre, and at least one filler material, e.g. water scavengers, hollow microspheres or silica.

Description

SPECIFICATION Improvements in or relating to phenolic materials The present invention relates to improved phenolic materials.

In view of current and pending legislation concerning the use of asbestos in the building and allied industries, considerable efforts are being made towards developing substitute materials which are both technically and economically attractive.

By practice of the present invention there may be provided a phenolic material which has the fire resistance and mechanical properties necessary to act as a substitute for certain types of asbestos.

According to the present invention there is provided a phenolic material, which comprises the product obtained by polymerizing a phenolic resin alone or in admixture with at least one other resin, for example an epoxy resin, the polymerization being effected in the presence of a catalyst, a reinforcing material and at least one filler material.

The phenolic resin used in producing the phenolic material of the present invention may be in the form of a liquid, solution, powder, etc. However, the form in which the resin is utilized may depend on the specific requirements of the phenolic material and its end use. Preferably, the phenolic resin is utilized in the form of a liquid.

Phenolic resins for use in producing the phenolic material of the present invention include resins of the resol type, for example prepared by the chemical condensation of a phenol, e.g. phenol, with formaldehyde, paraformaldehyde or like material. Preferably, the resol resin is prepared by condensing 1 mole of a phenol with from 1 to 3 moles of formaldehyde, paraformaldehyde or like material in basic media.

Resol type resins can, under suitable conditions of pH, be thermoset to the resite state.

A suitable phenolic resin for use in the present invention is Lankro LM 36 (a product of Lankro Limited).

In one embodiment of the present invention, the phenolic resin is copolymerized with at least one other resin. Resins suitable for copolymerization with the phenolic resin include epoxy resins. The epoxy resin should be a liquid epoxy resin, for example, a liquid bifunctional epoxy resin and may be obtained by condensing epichlorohydrin with polyhydroxy compounds such as Bisphenol A, for example by condensing 1 mole of Bishphenol A with 2 moles of epichlorohydrin.

Suitable epoxy resins for copolymerizing with phenolic resin include CY 219 (a product of Ciba-Geigy Limited) and Epikote 828 (a product of Shell Chemicals).

When the phenolic resin is copolymerized with an epoxy resin, the epoxy resin is preferably utilized in an amount of from 2 parts by weight to 20 parts by weight per 100 parts by weight of the phenolic resin.

The epoxy resin, when present, toughens and generally enhances the mechanical properties of the phenolic resin, contributing to the impact and other strength parameters of the final product.

The catalyst or hardener used in producing the phenolic material of the present invention may, for example, be an inorganic or organic acid catalyst. Suitable organic acids include para toluene sulphonic acid, which may be obtained from Lankro Limited under the name "Phencat 38", and para cresol sulphonic acid.

Suitable inorganic acids include phosphoric acid and mineral acids such as sulphuric acid and hydrochloric acid.

Adducts of the organic or inorganic acids may be utilized so long as they have the desired pH lowering effect.

If mineral acids are utilized as the catalyst, then they should preferably be sufficiently diluted in order that the safety and corrosion problems associated with the use of concentrated mineral acids are avoided or substantially reduced. Because of the potential safety and corrosion problems associated with the use of mineral acids, the organic or weak inorganic acids are preferred for use as the catalyst.

The catalyst may, for example, be utilized in an amount of from 10 parts by weight to 30 parts by weight per 100 parts by weight of the phenolic resin.

When acids are utilized as the catalyst, they may, for example, be in the form of 20 to 70% solutions. In this form, the acids may, for example, be present at levels of from 5 to 25% by weight relative to the weight of phenolic resin utilized.

Suitable materials for use as the reinforcing material include fibrous materials such as glass fibres and carbon fibres. Glass fibres are preferably used in the form of chopped glass fibres, e.g., of approximately ĭnch (approximately 6 mm) and/or approximate i̇nch (approximately 12 mm) length.

The reinforcing material is preferably utilized in an amount of up to 20 parts by weight, e.g., from 5 parts by weight to 20 parts by weight, per 100 parts by weight of the phenolic resin. Preferably, the reinforcing material is utilized in an amount of at least 3 parts by weight per 100 parts by weight of the phenolic resin.

The presence of the reinforcing material improves the mechanical properties of the phenoiic material, especially when it is formed into sheets.

Filler materials which may be used in producing the phenolic material of the present invention include water scavengers, non-combustible hollow microspheres, for example hollow ceramic microspheres (H.C.M.), and silica, for example sand.

The term "water scavenger", as used herein, refers to a material that will absorb water but will remain in a relatively dry condition, for example Plaster of Paris (2Ca SO4.H2O)or silica gel.

Deliquescent materials, such as calcium chloride, are not intended to be included within the scope of the term "water scavenger" since they absorb so much water that they eventually dissolve in it and are, therefore, unsatisfactory for use in the phenolic material of the present invention.

The water scavenger, if present, serves to remove water of condensation and any water present in the resin(s). For example, using Plaster of Paris (2Ca SO4.H2O) as the water scavenger, a high hydrate is formed (Gypsum, CaSO4.2H2O) on absorption of water.

When present, the water scavanger is preferably present in an amount of from 10 parts by weight to 100 parts by weight per 100 parts by weight of the phenolic resin.

The non-combustible microspheres, when incorporated in the phenolic material of the present invention are preferably present in an amount of up to 100 parts by weight, for example from 10 parts by weight to 50 parts by weight, per 100 parts by weight of the phenolic resin.

When hollow ceramic microspheres are utilized as the non-combustible microspheres, they act as an excellent insulative and non-flammable ceramic filler contributing to the het resistance of the final phenolic material product.

Silica, when utilized as a filler material in the phenolic material of the present invention, will normally be utilized in the form of sand for economic reasons and will preferably be present in an amount of up to 100 parts by weight, for example up to 60 parts by weight, per 100 parts by weight of phenolic resin. When present, silica acts as a good high-temperature, a nonflammablefiller, which also imparts useful hardness to the final product.

The present invention will now be further illustrated by way of the following Examples: EXAMPLE 1 Sheets were cast from the following four formulations: Formulation (Parts by weight) Component A B C D Phenolic Resin (e.g., Lankro L M 36) 100 100 100 100 Catalyst (e.g., Phencat 38) 18 25 24 25 Hollow ceramic microspheres 20 20 20 20 Sand 20 20 30 50 Plaster of Paris 60 60 60 60 Glass fibre (approximately 1/4 inch or 6 mm) 10 10 10 10 In the above formulations, no epoxy resin was used for purposes of enhancing resin strength.

Formulation A was observed to cure very slowly.

Formulation B cured more rapidly than formulation A.

Formulation C cured as for formulation B but produced a harder final product.

Formulation D was found to produce an even harder product than formulation C, but was more difficult to mix due to the high level of additives. The gel time of this formulation was observed to be approximately four minutes and the cure, thereafter, was very rapid.

Formulation A, B, C and D are suitable for use as a replacement for asbestos.

EXAMPLE 2 This Example illustrates a formulation based on a phenoliclepoxy copolymer. The formulation utilized was as follows: Component Parts by weight Phenolic resin 100 Epoxy resin 5 Catalyst 24 Sand 50 Plaster of Paris 60 H.C.M. 50 Glass fibre 10 This formulation was observed to produce, rapidly, a strong, fire-resistant sheet.

The phenolic materials of the present invention, when produced in sheet form, may have one or more of the following properties: (1) a specific gravity of approximately 1.3, (2) a pink/red colour which darkens in daylight, (3) a water absorption of approximately 10% after 24 hours total immersion, (4) they do not burn in air, (5) under forced combustion little or no smoke is generated, (6) no toxics, other than minimal quantities of carbon monoxide are evolved upon forced burning, (7) the sheets ablate or sublime at 1 mm/3.5 minutes under a butane torch burning at approximately 1200 to 1 4000C with constant direct flame impingement, and (8) the sheeting can be fixed to other materials and substrates by bonding, screwing and other techniques common to those employed for working with traditional asbestos sheeting.

It will, of course, be clear to one skilled in the art that minor amounts of materials, other than the phenolic resin, catalyst, reinforcing material, filler(s) and optional copolymerizable resin(s), may be incorporated in the phenolic material of the present invention.

Claims

1. A phenolic material, which comprises the product obtained by polymerizing a phenolic resin alone or in admixture with at least one other resin, the polymerization being effected in the presence of a catalyst, a reinforcing material and at least one filler material.

2. A phenolic material as claimed in claim 1, in which the phenolic resin is a liquid phenolic resin.

3. A phenolic material as claimed in claim 1 or claim 2, in which the phenolic resin is a resol type phenolic resin.

4. A phenolic material as claimed in claim 3, in which the phenolic resin is prepared by the chemical condensation of a phenol with formaldehyde or paraformaldehyde.

5. A phenolic material as claimed in claim 4, in which the phenol and formaldehyde or paraformaldehyde are condensed in a molar ratio of 1:1 to 3, in basic media.

6. A phenolic material as claimed in any of claims 1 to 5, in which the phenolic resin is copolymerized with an epoxy resin.

7. A phenolic material as claimed in claim 6, in which the epoxy resin is a liquid epoxy resin.

8. A phenolic material as claimed in claim 7, in which the epoxy resin is obtained by condensing epichlorohydrin with a polyhydroxy compound.

9. A phenolic material as claimed in claim 8, in which the epoxy resin is obtained by condensing epichlorohydrin with Bisphenol-A in a molar ratio of 2:1.

10. A phenolic material as claimed in any of claims 6 to 9, in which the epoxy resin is used in an amount of from 2 to 20 parts by weight per 100 parts by weight of the phenolic resin.

11. A phenolic material as claimed in any of claims 1 to 10, in which the catalyst is an inorganic or organic acid catalyst.

12. A phenolic material as claimed in claim 11, in which the catalyst is para toluene sulphonic acid, para cresol sulphonic acid, phosphoric acid or a mineral acid.

13. A phenolic material as claimed in claim 12, in which the mineral acid is sulphuric acid or hydrochloric acid.

14. A phenolic material as claimed in any of claims 1 to 13, in which the catalyst is used in an amount of from 10 to 30 parts by weight per 100 parts by weight of the phenolic resin.

15. A phenolic material as claimed in any of claims 11 to 13, in which the catalyst is used in the form of a 20 to 70% solution.

16. A phenolic material as claimed in claim 15, in which the catalyst is used in an amount of from 5 to 25% by weight, relative to the weight of phenolic resin utilized.

17. A phenolic material as claimed in any of claims 1 to 16, in which the reinforcing material is glass fibre or carbon fibre.

18. A phenolic material as claimed in claim 17, in which the glass fibre is in the form of chopped glass fibres.

19. A phenolic material as claimed in any of claims 1 to 18, in which the reinforcing material is used in an amount of up to 20 parts by weight per 100 parts by weight of the phenolic resin.

20. A phenolic material as claimed in claim 19, in which the reinforcing material is used in an amount of from 5 to 20 parts by weight per 100 parts by weight of the phenolic resin.

21. A phenolic material as claimed in any of claims 1 to 20, in which the at least one filler material is selected from water scavengers (as hereinbefore defined), non-combustible hollow microspheres and silica.

22. A phenolic material as claimed in claim 21, in which the at least one filler material comprises a water scavenger which is plaster of Paris or silica gel.

23. A phenolic material as claimed in claim 21 or claim 22, in which the at least one filler material comprises non-combustible hollow microspheres which are hollow ceramic microspheres.

24. A phenolic material as claimed in any of claims 21 to 23, in which the at least one filler material comprises silica in the form of sand.

25. A phenolic material as claimed in claim 21 or claim 22, in which the water scavenger is present in an amount of from 10 to 100 parts by weight per 100 parts by weight of the phenolic resin.

26. A phenolic material as claimed in claim 21 or claim 23, in which the non-combustible hollow microspheres are present in an amount of up to 100 parts by weight per 100 parts by weight of the phenolic resin.

27. A phenolic material as claimed in claim 26, in which the non-combustible hollow microspheres are present in an amount of from 10 to 100 parts by weight per 100 parts by weight of the phenolic resin.

28. A phenolic material as claimed in claim 21 or claim 24, in which the silica is present in an amount of up to 100 parts by weight per 100 parts by weight of the phenolic resin.

29. A phenolic material as claimed in claim 28, in which the silica is present in an amount of up to 60 parts by weight per 100 parts by weight of the phenolic resin.

30. A phenolic material as claimed in claim 1 and substantially as hereinbefore described with reference to either of the Examples.