CA1048676A - Resin composition comprising aralkylene phenol resin and formaldehyde condensate - Google Patents
Resin composition comprising aralkylene phenol resin and formaldehyde condensateInfo
- Publication number
- CA1048676A CA1048676A CA74190153A CA190153A CA1048676A CA 1048676 A CA1048676 A CA 1048676A CA 74190153 A CA74190153 A CA 74190153A CA 190153 A CA190153 A CA 190153A CA 1048676 A CA1048676 A CA 1048676A
- Authority
- CA
- Canada
- Prior art keywords
- resin
- composition according
- condensate
- melamine
- weight
- 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.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/35—Extraordinary methods of construction, e.g. lift-slab, jack-block
- E04B1/3511—Lift-slab; characterised by a purely vertical lifting of floors or roofs or parts thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
- C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
- C08G2261/31—Monomer units or repeat units incorporating structural elements in the main chain incorporating aromatic structural elements in the main chain
- C08G2261/312—Non-condensed aromatic systems, e.g. benzene
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Conveying And Assembling Of Building Elements In Situ (AREA)
Abstract
ABSTRACT
A resin composition is provided comprising (a) a resin having repeating units of formula
A resin composition is provided comprising (a) a resin having repeating units of formula
Description
- 2 - 1~ 4 8 ~7 6 The present invention relates to resin compositions and the cured produc~s obtainable therefrom.
British Patent Speci~ication No. 115020~ describes the production of resins having repeating units of the formula ; - CH2 - R - CH2 - Ar -1 (C~2ArOH)n OH
wherein R is an aromatic hydrocarbon or aromatic hydrocarbon-oxy-aromatic hydrocarbon group, which optionally has inert ; substituents and Ar is the residue o~ a phenolic compound here-; inafter defined and n is O or 1. British Patent Specification No. 1305551 describes the curing of these resins with epoxides havinig 2 or more epoxy groups per molecule to form cured pro-ducts.
The above resins can be used for the production of sur~ace coatings and laminates having good chemical and high temperature ageing resistance and electrical properties.
15The coatlngs are prepared by dissolvlng the resin and a sultable curlng agent e.g. hexamethylene tetramine as in British Patent 1150203 or the epoxides as in British Patent 1~05551 in an organic solvent e.g. 2 - ethoxy ethanol or methyl isobutyl ketone, applying the solution to the sur~ace to be coated, evaporating the solvent and then curing the resultant coating ; to an infuslble product. I~ the coating ls to be used at a high temperature or if particular propertles are requlred of it, post curing e.g. at 160 - 250C may also be needed. We have found that the above resins tend to produce cured surface coat-ings showing ~Iclssingfl. Ciising is a well known surface coating phenomenon (see e.g. 'Palnt ~llm Defects' Manfred Hess, pub- -~
lished by Chapr.lan and Hall 2nd edltion 1955J p.436) and is associated wlth non-wettlng of the surface beln~ coated.
; Normally the resln laminates are prepared ~ia i~p~gnatiQn o~
glass cloth, or carbon fibre or asbestos cloth with a solutio~
of the resln ln an organic solvent e.g. methyl ethyl ketone.
Such laminates exhibit a wide range o~ utility. However, for certain appllcations lt may be desirable to incorporate additlonal materlals in the laminate, for example poly tetra-~luoroethylene or certain flame retardent materials, the latterespecially for epoxy curing agents. Hltherto, it has not been ~ound possible to produce completely satis~actory laminates ~rom resins incorporatlng such additional materials.
The above resins can also be used as adhesives but the ad-heslve strength of the cured resin is not very high because on curing blisters are ~ormed.
,. `3~ ' - ~ . : -: ` `
~ 8~76 ; - The present invention provides a resin composition which comprises . (a) a resin having repeating units of the formula 2~ n .. and preferably consists essentially of such repeating units, wherein Rl is a divalent or trivalent aromatic hydrocarbyl or divalent or trivalent aromatic hydrocarbyl-oxy-aromatic hydro-carbyl group, or inertly substituted derivatives thereof, and ,. 10 Ar is a residue formed by removal of 2 nuclear hydrogen atoms from a phenolic compound having 1-3 hydroxyl groups and at least 2 nuclear hydrogen atoms, and n is O or 1, and ; (b) an uncured or partially cured condensate of formaldehyde ,.;, s.~ and melamine, the weight ratio of resin to condensate being i 99:1 to 1:99.
~ The resin composition may also contain 0.5 to 100%
. by weight (based on the weight of the resin) of an inorganic . dispersing agent having at least one dimension less than . 100 mu and all dimensions less than 15u and stable to 150C.
;...... 20 The resin compositions of the invention may also contain a particulate material of particle size 0.2,u - 2 mm, ~i- preferably 1~ - 1 mm, and stable to 150C which is preferably s at least one of a flame retardent, lubricant, ... .
,. . .. .
; .
... .
',~ , .; - 3 -. . .
, .
. ~ .
l E
., 1~41~ 76 metal powder, and formaldehyde condensate with a nitrogen-ous compound (as hereinafter described).
We have found that the composition comprising resin and as dispersing agent finely divided silica of particle size 1 - 80 m,u, can be used with the curing agent to prepare a coating solution, which after application, evaporation ` of solvent and heating/curing, produces a coated layer in which the problem of cissing is greatly reduced if not elimin-ated. If desired the composition may also contain the particulate material.
The compositions of the invention comprising resin, the dispersing agent and curing agent and optionally the parti-culate material can be cured with decreased production of .
blisters in the cases when volatile materials are produced on curing e.g. with haxamethylene tetramine and thus can be used as adhesives with high adhesive strength.
"t The amount of inorganic dispersing agent is usually `~ !
0.5 - 20% (by weight based on the weight of the resin) when the resin composition is to be used for producing coatings ; 20 showing reduced cissing or for adhesives showing the cured ~ form reduced blistering, preferred amounts being 1 - 10%
i in both cases. When the resin composition also contains the particulate materials, an amount of 0.5 - 100~ (based on the weight of resin) of dispersing agent is used, the higher values being appropriate when the dispersion of resin, dispersing agent and particulate material is to be used as a "masterbatch" for subsequent dilution with further resin solution; amounts of dispersing agent in the region 1 - 20%
are preferred when the resin dispersion is to be used as such.
The amount of particulate material in the resin compo-: sition i~ usually 1 - 100% (by weight of resin), the higher ' .:
;
;-- ~ - 4 -. ~
. .
~: - .' .'. :
~`
~;~)4~3~76 :
values again being used when the composition is to be used , . I
as a masterbatch for subsequent dilution with more resin solution. Amounts of particulate material in the range 1 - 30% are suitable for dispersions to be used as such, the r.' preferred upper limit being dependent on the nature of the particulate material. The usual amounts of antimony oxide, chlorine and/or phosphorus containing organic flame retard-; ants and metal powders are respectively 5%, 10% and 25~.
, In the dispersions of the invention comprising resin, dispersing agents and particulate material (optionally with -curing agent) the amount of dispersing agent depends on the ~; nature and amount of the solvent and particulate material and on the degree of dispersion required.
The inorganic dispersing agent, which is stable to at least 150C, preferably to at least 200C, usually has a minimum dimension of at least lm~u. It is preferably finely i~ divided silica of average particle size 3 - 80m,u especially X. .. - ..
7 - 40m,u, e.g., the fumed colloidal silica sold under the .
i trade marks "AEROSIL" and "CAB-O-SIL", finely divided ;' 20 chrysotile asbestos e.g. of diameter about 25mp and length 5 to 10 ,u such as that sold under the trade mark "SYLODEX"
which may optionally be mixed with silica, and finely ; divided hydrous magnesium aluminium silicates e.g. organic derivatives of mont-morillonite with a platelike structure of thickness 2 to 4m,u and maximum dimension 0.5 to l~, such as that sold under the trade name "BENTONE".
Examples of the flame retardants are organic compounds containing halogen and/or phosphorus atoms such as poly- -halogenated organic compounds, preferably those in which the halogen is .,:, i~:
, ;
.... . .
~ 5 -,',"., ~.
..... .. . .
chlorine or bromine, and especially those in which the organic nucleus is an aromatic nucleus, e.g. decachlorobiphenyl, hexa-bromobenzene, hexachlorobenzene and tetrabromobisphenol A, and tris (bromopropyl) phosphate, tris (pentabromophenyl) phosphate and tris (dichloropropyl) phosphate. These compounds, which may be soluble in the resin solution, are used in con~unction ; with antimony o~ide, which is insoluble. Other flame retardants are metal borates e.g. borates of metals of Gp. 2 (of the Periodic Table published in Bull. Soc. Chim France January 1966 ?
such as zinc, calcium or barium. Antimony oxide may also be present in admixture with the borates.
The lubrlcant particulate materials may be homo polymers of tetrafluoroethylene (PTFE) and copolymers thereof with other fluorinated olefins of 3-6 carbon atoms e.g. perfluoropropylene, or may be inorganic in nature, such as graphite~ molybdenum di sulphide or metal salts of fatty acids of 8-20 carbon atoms, e.g.
; stearic acid, zinc and calcium stearates being preferred. In-corporation of the lubricant in the resin composition enables cured products e.g. bearings having a low coefficient of fric-; 20 tion to be obtained.
- The metal powder, that may also be the particulate material, ~-- may be aluminium powder or zinc dust. Metal powders are generally used when the resin, dispersing agen~ and metal ; powder is for use in surface coating applications, but could be used for producing laminates.
The particulate material can also be a formaldehyde condensate formed frrom f~r~alqehyde (or a compound yielding it in situ such . . , p a~^aJDr~n~/a~ ~C
D as poraformaldch~ or hexamine) and a nitrogenous compound Z Y
containing a N = C - NX2 group (or a group enolisable to said :. Z O
group such as a - N - C - NH2 group), wherein Y represents an oxygen, sulphur or nitrogen atom, and Z represents a hydrogen, carbon or oxygen atom or Y and Z together form a direct bond.
Preferably the nitrogenous compound contains at least 2 - NH2 : groups and preferably has 1-6J especially 1-~ carbon atoms.
~5 Examples of the nitrogenous compound are urea, melamine, thio ;~ urea, cyanamide, dlcyandiamide and guanidine. Such condensates ;~ which may be in the cured, partially cured or uncured form are well known and are described in, for example "Aminoplastics"
by C.P. Vale, published Cleaverhulme Press, London 1950. The preparation of the uncured condensates is described further below. The addition of these formaldehyde condensates to the resin compositions improves the electrical properties of the cured product.
. . .
48~76 The resin is preferably prepared, following the general proce~ure described in British patent specification No. 1150203, by reacting (1) an aralkyl ether of the general formula R' ` (-CH2OR)a and/or an aralkyl halide of the general formula R' (CH2X)a, wherein R' is a divalent or trivalent aromatic hydrocarbyl or aromatic hydro-carbyloxy aromatic hydrocarbyl radical,R' optionally containing inert substituents in the aromatic nucleus, R is an alkyl radical containing 1-5 carbon ;~ atoms, X is chlorine, bromine or iodine and _ has a value of ~ -2 or 3 with (2) a molar excess, normally of at least 1.3:1, preferably in the range of 1.4:1 to 2.5:1 of a phenolic compound or a phenolic compound and a non phenolic compound containing an aromatic nucleus. If a is 3 then n is 1 and a further ArOH
. ~ group may be bonded to R' through another methylene bridge.
. In these general formulae R' represents any divalent or i........... trivalent aromatic hydrocarbyl or aromatic hydrocarbyloxy .il aromatic hydrocarbyl radical, for example the m - or p-phenylene . radical, the diphenylene radical, the diphenylene oxide radical ";
,,~ ~0~, :~ ~ ' - -the radical ' or the radical .....
:., ~ 7 -, :.: -.. . .
`':
,., 1~41~76 ` Thus both mono nuclear, and fused and unfused di-and poly nuclear radicals may be represented by R', though mononuclear `` radicals are preferred because the cured products therefrom ~ have higher strength at high temperatures than those from di .` and polynuclear radicals. Preferably R' does not represent a -diphenylene or diphenylene oxide radical when the aralkyl halide is used to prepare the resin. The resin is preferably pre-pared from the aralkyl ether, especially ones in which R is an alkyl radical of less than 4 carbon atoms e.g. a methyl radical.
The preferred compounds for a reaction with the phenolic com-` pounds are those in which a has a value 2, particularly the p-xylylene dihalides for example p-xylylene dichloride and the ,~ p-xylylene dialkyl ethers for example p-xylylene - glycoldi -`~'` methylether.
,..;~
... .
,.. '; ~ .
' . ~
,,',, :-' ~. ~
.: ~
;~.,. , ~.
.. . .
", ~, '',i,~ ''' :
:~
~... I
,., ~ . ~
.,.,.
~:.,,. . : .
. .
. - 7a -: ~.
.,?, . :
:,''';
: .,;
~ E
, . .
.: ,.
4iY~76 .~
If desired the Rl radical may contain substituents, for ; example methyl radicals, attached to the aromatic nucleus, ,`; provided the said substituents are inert under the conditions of the reaction. In fact the presence of chlorine or fluorine atoms in some or all of the available positions in the aroma-tic nucleus has been found advantageous in that it leads to improved flame resistance in the resulting polymeric products~
Examples of such substituted aralkyl ethers and aralkyl halides, which may be employed according to this invention, are 2,3,5,6 -tetrachloro - 1,4 - di(chloromethyl) benzene and 2,~,5~6 -tetrachloro - l,4 - di(methoxy-methyl) - benzene.
~` The phenolic compound includes any compound or mixture of ;~` compounds derived from benzene and containing l to 3, preferably l or 2, hydroxyl radicals ~oined to the aromatic nucleus, there being a total of not more than ~ substituents attached to ring carbon atoms of the benzene nucleus apart from the one essen-tial hydroxyl group. Thus the phenolic compounds may be of formula OH
,........................ .
~ (R3)1 _ 3 .
where each R~ is hydrogen, hydroxyl, amino, alkyl of 1 to 8 carbon atoms, e.g. methyl, ethyl, isopropyl, tert, butyl or tert. octyl, phenyl and hydroxyphenyl alkyl e.g. hydroxy phenyl - methylene, - ethylene and - isopropylidene. Examples of these phenolic compounds are phenol, p - cresol, m - cresol, ; resorcinol, catechol, 4-methyloatechol, isopropyl catechol, diphenylol propane (bis 2,2- (4-hydroxy phenyl) propane), ; diphenylolethane, monoalkyl phenols such as p-ethylphenol, p-tert. butyl phenol and p-tert. octyl phenol, m - and p -phenyl phenol p - amino phenol, pyrogallol and phloroglucinol.
, Mixtures of the phenols can be used such as a monophenol with , .
a dihydric phenol e.g. resorcinol with phenol itself, or mix-tures of diphenols e.g. 4-methyl catechol and catechol and/or resorcinol such as that sold as a phenolic coal tar fraction.
Examples of the compound containing aromatic nuclei which may be mixed with the phenolic compound in the formation of the resin are dlphenyl - or dibenzyl - etherJ terphenyl, diphenyl-~`i amine, diphenyl sulphide diphenyl, anthracene, diphenylsulphone, ;~ triphenyl phosphate, octaphenylcyclotetrasiloxane, aryl sub~
stituted borazoles and metal complexes such as ferrocene.
The proportion of aromatic compound can vary within wide limits but i~ not sufficient to prevent satisfactory curlng of the ''., :
. ' .
` ` 1~48~7~
reaction product with the hardening agent. Further details of the aromatic compound and its modes of use in the reaction of - phenol and dihalide or diether are given in British Patent Specification No. 1150203.
The curing agent is a condensate of formaldehyde with melamine in the uncured or partly cured form. The condensates - are preferably made by reaction of one molar proportion of ~-~
; melamine with 1-10 molar proportions of formaldehyde (or formaldehyde yielding compound), especially 1:2 to 1:8 molar proportions, in neutral or alkaline conditions. The amount of curing agent needed for reaction with the resin in general depends on the nature of the curing agent, in particular on the number of free methylol groups on it and also the degree of curing desired. Thus less hexamethylol-melamine will generally be needed than trimethylolmelamine for equivalent curing. The resin is mixed with the formaldehyde condensate in a weight ratio of 1 - 99 : 99 - 1, preferably 50 - 95 : 50 - 5 and especially ;
, 65 - 85 : 35 - 15.
,.. ; .
The formaldehyde condensate in its uncured or partially ` 20 cured forms is used as a curing agent whether or not an i inorganic dispersing agent is also present. When the comp-`~ osition comprising resin (a) and condensate as curing agent is to be used as a moulding powder, the components can be dry mixed, formed into a moulding powder and subsequently moulded :,. -"
;' :
. .
, / .
`', ., I
l E
-- lo - lV48~76 under heat and pressure to rorm cured moulded articles. When the composition comprising resin (a) and condensate as curing agent is to be used ~or coating purposes or for impregnation in the production of laminates, it is preferred, but not essential, to incorporate the inorganic dispersing agent as well so that the liquid dispersion used for coating or dis-` persion may be as uni~orm as possible. The conditions for curing are the same as for hexamine curing. The use of the condensates or the nitrogenous compounds as curing agents en~
ables cured products with good electrical properties especially high arc and tracking resistance, and high heat resistance to be obtained.
The compositions of this invention may also contain in-organic fillers, e.g. asbestos flour, mica or chopped glass strands. The inorganic filler and resin will normally be present in a weight ratio of o.o5 r 1 to 4.0 : 1. Other in-gredients such as pigments, accelerators, and antistaining agents e.g. magnesium oxide, or titanium dloxide may also be present if desired.
- 20 The compositions of the ~nvention can be made by mixing the various components in any order, but it is convenien~ to add the curing agent last. me mixing can be carried out in any convenient method such as dry blending to form a powder for moulding (optionally with subsequent addition of organic solvent to make the desired liquid ~or coating and impreg-natlng purposes) or blending in solutions in an organic solvent to prepare the liquid directly. The solvent may be a dialkyl ketone o~ 3-8 carbon atoms e.g. methyl isobutyl ketone, methyl ~, ethyl ketone, or methylisoamyl ketone, isophorone, diacetone i': 30 alcohol,a cycloalkyl ketone of 5-7 carbon atoms e.g. cyclo-hexanone, an alkoxy alkanol with 1-6 carbon atoms in the alkoxy group and 2-7 carbon atoms ln the alkanol group such as 2 - ethoxyethanol, alkyl ethers thereof with 1-6 carbon atoms in the alkyl group e.g. the methyl ether,esters o~ the ~5 alkoxy alkanols with alkanoic acids of 2-6 carbon atoms e.g.
the acetate, any Or whlch solvents can be (in an amount suf-ricient to maintain the resin in solution) mixed with an ` aromatic hydrocarbon preferably a monocyclic one of 6-12 carbon atoms such as benzene, toluene or xylene or an aliphatic ~; 40 hydrocarbon such as white spirit or solvent naphtha or an al~anol e.g. o~ 1 to 6 carbon atomsJ such as methanol, ethanol - or n - butanol. me resin is usually present in the organi~
solvent solutions in an amount o~ 5 - 90~ preferably 20 - 65 e.g. 20 - 50~ by weight. The mixing can be carried out at a 4~76 low temperature e.g. 20 - ~0C and ~he mixture stored until required, but the mixing of the curing agent with the remainder of the components is usually carried out at a higher tempera-ture e.g. about 60 C for several hours e.g. 1 - 4 hrs. and then the mixture cooled to room temperature and stored until required.
The liquid dispersed mixture of resin, dlspersing agent (if present), particulate material (if present), solvent and curing agent (and other additives if present) can be used as a coating solution or as an lmpregnant for the production of laminates.
me solvent from the liquid dispersed mixture can also be evaporated and the residual product used as a moulding powder; this technique ls pre~erred for the production of moulding powders containing long fibres, which may be broken in the dry mixing method.
The compositions of the invention are cured by heating usually at above 70C and preferably over 100C e.g. 150 -;~ 175C. Post curing if needed is usually carried out at 160 C -250C. The time needed for post-curing varies according to the properties of the desired product, and the temperature of use ; of that product.
For the use of the compositions of the invention for coating, the mixture of resin9 dispersing agent (if present), curing agent and solvent (together with any other additives) can be applied by any means to the surface to be coated e.g.
by painting, spraying or lmmersion. Normally the surface will be of metal e.g. ~errous metal such as mlld steel but other substrates suoh as wood, plastic material or inorganic mater-, ials such as porcelain or cement can be coated, if desired.
~0 After coating the solvent is evaporated and the layer cured.
~hen the dispersing agent is finely divided silica, the curqd layer shows little or no "cissing'.
i In the use of the compoæitions of the invention as adhesives the mixture of resin, dispersing agent, curing agent and sol-vent, (together with any other additives) can be applied to one or both of the surfaces to be adhered together by any means e.g. painting, spraying or immersion. Examples of suitable surfaces are those of metals e.g. ferrous metal such as mild ~teel but other substrates such as plastics materials e.g. those described in British Patent 115020~, optionally with reinforcement e.g. glass or asbestos fibres, or inorganic materials such as porcelain or cement can be used. After the applications, the solvent is evaporated, the surfaces brought together and the combination of surfaces and intervening layer .,, '' .
,, : ' ~ ' .
1~ 8~
cured. Because of the reduction in the number and/or size of blisters produced, the bond formed by the combination has high strength.
In the use of the compositions of the invention for making laminates, the liquid mixture is applied to the laminate base. Suitable laminate bases are glass cloth or carbon ~ibre agglomerates although other fibrous materials such as asbestos cloth may also be employed if desired.
Such materials are impregnated with the dispersed mixture as described above and then dried. Typically the fibrous base is passed through a bath of the resin dispersion.
The fibrous material into which the resin has been , . .
impregnated is then subjected to a precure heat treatment at about 140C~ often for about 10 minutes. The laminates are then pressed at a tempPrature above 160C often in the range 170 to 190C at a pressure of from 7 to 105 kg/cm2, although pressures above 35 kgjcm2, often of about 70 kg/cm2 are normally employed. Normally pressing will be carried out for a period of at least 1/2 hour, often for about an ^ 20 hour, depending upon the conditions of temperature and pressure employed.
; For optimum results the laminates are subsequently ,.
post cured. The temperature and time employed for the pos-t cure operations are dependent upon each other. For example a post cure in the temperature range 140 - 190 C may take ;~ up to 7 hours whereas one in the range 220 - 250 C may be accomplished in five hours. However, it is normally desirable that the material is heated to a temperature at least in the range 190C - 220C.
. .
.
,' ''~ ' lV4~76 , The invention is illustrated in the following Examples:
Example I
Resin A
An aralkylene phenol resin was made by reacting 705g (7.5 moles) of phenol and 830g (5 moles) of p-xylylene dimethyl ether (technical grade) in the presence of lml. of diethyl sulphate as catalyst. On heating to 130 - 200C
methanol was lib~rated and distilled out. The product on '; cooling, was a red brown solid having a softening point of ,~ 10 97& . -Resin B
126g (1 mole) of melamine and 225mls (3 moles) of a 40% formalin solution were mixed together and a few drops :~ of dilute sodium hydroxide were added to make the mixture .
slightly alkaline. The resultant solution was heated to ~ 75& with stirring and on cooling a white pre~ipitate was `;~ formed. This was filtered off and dried-to obtain a white powder, trimethylol melamine nominally.
Resin C
7.5gms of resin A were mixed th~roughly in a powdered state with 2.5gms of resin B. The mixture was put into an aluminium dish and placed in an oven at 200C. A hard infusible, insoluble mass was formed.
240gms of resin A were dissolved in a mixture of 240gms .. . . . . .
of ethyl methyl ketone and 80g of industrial methylated .:: . .
spirits. To this solution was added 80gms of resin B and ... .
6gms of fumed silica and these were dispersed using a high speed mixer. The resultant mixture was used to impregnate glasscloth "MARGLASS" (trade mark) 116T/P705 and the pre-preg produced was precured for 10 minutes at 135 C. This was cut into 25cm x 25cm squares and pressed into a laminate , ;
; - 13 -.~:
. .
'.,~
.. .. . .
- `` 1~48~76 at 175C,t70 kg/cm for 1 hour. The laminate produced was ~.. post-cured from 140 to 250C over 23 hours and had the .
. following flexural strengths .. Flexural measured strength at 20C 5700 kg/cm2 150C 2680 " "
~ 200C 1300 :s 250C 1016 " "
~'`' ' .
,. .
,;~, ~ .
.'1 ' . ' .
, .
. .
., ~ .
,.~.
.
.
, . . .
.,~, .
.
....
.
;,, .
, . . , .~:
- 14 - .
`;;:
,: .
.. :, . . ..
.. .
::; .
: .:
1q~4~3~76 ` SUPPLEMENTARY DISCLOSURE
,,'' ' :
In the main disclosure are described resin compositions which comprise a resin having repeating units of the formula .,i .
~H R' CH Ar (CH2ArOH)n OH
and an uncured or partly cured condensate of formaldehyde and melamine. The formaldehyde condensate acts as a curing agent for the resin to give cured products with good electrical properties and high heat resistance.
; We have found that if the weight of the condensate is 55 - 90% of the combined weight of resin and condensate, . , .
then the cured products have good arc and track resistance and : strength at high temperatures which may be accompanied by high heat resistance as well.
The compositions with the higher amounts of condensate comprise (a) a resin having repeating units of the formula -CH2 - R' - CH - Ar I
- (CH2ArOH)n OH
terminated with ArOH groups wherein R' is a divalent or trivalent ~ 20 aromatic hydro-carbyl or divalent or trivalent di(aromatic ; hydrocarbyl) oxy group, which optionally has at least one inert substituent and Ar is a residue formed by removal of two nuclear hydrogen atoms from a phenolic compound having 1 - 3 hydroxyl groups and at least two nuclear hydrogen atoms in ortho . ,, and/or para positions to a hydroxyl group, and n is 0 or 1 and ;` (b) a condensate formed from formaldehyde ( or a compound ~ yielding it in situ such as paraformaldehyde or hexamethylene,.............. .
tetramine) and melamine, said condensate being in an uncured - or partially cured form and provided 55 - 90% by weight of the total weight of resin and condensate.
:, . .~ . .;
: .
,,;
` i~48~76 ` The condensates are preferably made by reaction of "' one molar proportion of melamire with 1.2 - 10 molar proportions of formaldehyde (or less preferred, the equivalent amount of formaldehyde yielding compound) especially 1:2 to 1:8 molar ~ proportions, in neutral or alkaline conditions. The condensate : is uncured or partially cured, usually with not more than five repeat units derived from the nitrogenous compound. Preferably it is uncured with one structural unit derived from melamine and at least two hydroxymethyl groups attached to nitrogen atoms.
The two hydroxymethyl groups may be attached to the same or different nitrogen atoms. Preferably the condensate contains hydroxy methyl groups attached to nitrogen atoms in an average number from two, (and preferably from 2.5) to the maximum number of hydrogen atoms attached to nitrogen ato~s in the melamine. The condensate preferably contains 2 to 6, usually ; an average of 2.5 to 6, and especially 3 or 6 (as in trimethyl-~ olmelamine and hexamethylolmelamine) hydroxymethyl groups. An - average of 2.5 hydroxy methyl groups per molecule of melamine means that, for example, the condensate is a 1:1 molar mixture of a condensate with 2-, and a condensate with 3-hydroxymethyl ` groups per molecule of melamine.
~ The amount of formaldehyde condensate is 55 - 90%
; by weight of the total weight of resin and condensate. Amounts ; .:
i ` of 58 - 74%, eg. 60 - 70% are preferred as these amounts give cured products with high strength at high temperatures and , ~ . , moderate retention of strength after aging at high temperatures but coupled with a moderate comparative tracking index. Amounts j of 74 - 90%, eg. 80 - 90%, are used if a much higher comparative '!, tracking index of the cured products is wanted.
The resin has repeating units of formula '~''"', .., .
.. 31~
g~i76 - CH2 - R' CH - Ar -:~ - (CH2ArOH)n OH
and is terminated by ArOH groups. Preferably the resin contains substantially only units derived from ArOH and units of skeletal structure -- -- - C - R' - C -(- C ~)n The resin is preferably made,following the general procedure described in British Patent No. 1150203,by reacting (1) an aralkyl ether of the general formula R'(CH2OR)a and/or aralkyl halide of the general formula R'(CH2X)a, wherein R', R, a and X are as defined above, with a molar excess of a phenolic compound, or a mixture thereof with a nonphenolic compound containing an aromatic nucleus. While R' is preferably an unsubstituted aromatic hydrocarbyl group, especially a m-; or p- phenylene group, if desired the R' radical may contain at least one substituent attached to the aromatic nucleus, which substituent is an alkyl group of 1 to 6 carbon atoms, e.g.
a methyl group a phenyl group or a halogen atom, e.g. a chlorine or bromine atom. These substituents are inert under the con~
ditions of the reaction. In fact the presence of chlorine or ) fluorine atoms in some or all of the available positions in the aromatic nucleus is advantageous in that it leads to improved flame resistance in the resulting polymeric products. Examples of such substituted aralkyl ethers and aralkyl halides, which may be employed according to this invention, are 2, 3, 5, 6 -; tetrachloro - 1, 4 - di (chloromethyl) benzene and 2, 3, 5, 6 -~" tetrachloro - 1, 4 - di(methoxy-methyl) - benzene.
:,, ~ The phenolic compound is any compound or mixture of ..
compounds derived from benzene and containing 1 to 3, preferably ~- 1 or 2, hydroxyl radicals joined to an aro~atic nucleus, at least two of the ortho and para positions to a hydroxyl :- .
r ~ ~ ~ 17 ~
~, .
" 1q~48~i76 :.
group b~ing unsubstituted and any non-hydroxlic substituents being inert under the conditions of the reaction. Thus the phenolic compounds may be of formula OH
~ (R3)1-3 where each R3 is hydroxyl, alkyl of 1 to 8 carbon atoms, e.g., methyl, ethyl, isopropyl, tertiary butyl or tertiary octyl, halogen e.g. chlorine, nitro, phenyl and bis(hydroxyphenyl)-alkyl, e.g. bis(hydroxy phenyl)- methylene, -ethylene and -isopropyl-idene. Preferably the phenolic compounds contain only onearomatic ring. Examples of these phenolic compounds are phenol, p - cresol, m - cresol, resorcinol, catechol, 4 - methyl-catechol, isopropyl catechol, d1phenylol propane (bis 2,2- (4-hydroxy phenyl) propane), diphenylolethane, monoalkyl phenols such as p-ethylphenol, p-tertiary butyl phenol and p-tertiary .:
octyl phenol, m - and p - phenyl phenol, pyrogallol and phloroglucinol. A mixture of phenol and beta naphthol as des-cribed in our British Patent Specification No. 1363531 may be used. Mixtures of the phenols can be used such as a mono-phenol with a dihydric phenol, e.g. resorcinol with phenol itself, or mixtures of diphenols, e.g. 4-methyl catechol and ; catechol and/or resorcinol, such as that sold as a phenolic coal tar fraction. Preferably these particular mixtures or phenol itself resorcinol, or catechol are used.
The aralkylene compound of formula R'(CH2OR)a or ; R(CH2X)a is preferably substantially pure usually with at least 90% by weight of the expected compound, but technical grade materlals may be used. Thus technical grade p-xylylene glycol dimethyl ether can contain 65 - 90% of the expected 30 compound, 0.1 - 5% of p-methoxymethyl toluene, 0.1 - 10% of , - 18 -"', ,. . . . .
-..... . : - . : :
1~48~76 ~
p-tolualdehyde dimethyl acetal and 10 - 35% of p-methoxymethyl-benzaldehyde dimethyl acetal and small amounts of other im-purities. The amount of the acetal includes any of the corres-ponding aldehyde present.
The reaction to form the resin is carried out with one mole of aralkylene compound and a molar excess of the phenolic compound or mixture thereof with the aromatic com-pound. Preferably at least 1.3 moles of phenolic compound ~-(or mixture) per mole of aralkylene compound are used. From 1.3 to 3 moles of the phenolic compound are suitably employed for every mole of the aralkylene compound. When the molecular proportion falls below the specified 1.3:1 ratio and approaches ; 1:1 the reaction mixture exhibits an increased tendency to gel prematurely. When in the aralkylene compound a is 2 and the . , ~ratio of phenol to compound is greater than 2.5, the resulting ~-.7 products become more difficult to cure. Polymeric products having the highest softening points are obtained when the ratio of the phenolic compound to aralkylene compound is at the low end of the specified range. Preferably when a in the compound is 2 the phenolic compound is employed in a ratio of 1.3:1 to 2:1 e.g. 1.3 to 1 to 1.7 to 1, especially 1.4 to 1.6:1. When a in the compound is 3, the phenolic compound is preferably employed in a ratio of 2:1 to 3:1 e.g. 2.5:1 to 3:1.
The compositions of the invention are cured by heat-ing, usually at above 70C and preferably 100 - 180C, e.g.
~;~ 150 - 180C. Post curing may also be carried out, usually :~ .
, initially at 60 - 100C for 4 - 24 hours, and then at 160 -250C. The time needed for post curing varies according to .~i . .
~ the properties of the desired product, and the temperature of ,~ 30 use of that product; examples of times of curing at 100 - 180C
,: ., are 0.5 - 48 hours, e.g. 0.5 - 10 hours at 150 - 180C. The ,, , 19 ' !
: ' . ." . : ~ .
. .
,.'. '. ` ~' ' : .
'; -1~)41~i76 cured articles are usually in the form of moulded products or laminates.
In the production of laminates, a solution or dis-persion of the resin and condensate is used to impregnate a fibrous laminate base. The fibrous material into which the resin has been impregnated is usually then subjected to a precure heat treatment at 100 - 160C, often at 130 - 140C for 5 - 20 minutes, e.g. for about 10 mins. In the prepregs formed ` the resin and condensate have partly reacted. A stack of the prepregs is then pressed at a temperature above 160C, often in the range 170 - 190C at a pressure of from 100 to 1,500 psi, although pressures above 500 psi, often of about 1,000 psi are normally employed. Normally pressing will be carried out for a period of at least 1/2 hour, and generally up to 2 hours, often for about an hour, depending upon the conditions of temperature and pressure employed.
For optimum results the laminates are subsequently post cured, e.g. by heating outside the press (as in air circulating oven). The temperature and time employed for the post cure operations are dependent upon each other, and on the ; use of the product and the degree of post cure. Usually the post cure is at 60 - 100C for 4 - 24 hours, e.g. 12 - 24 hours at 80 - 100C, and then for at least 3 hours, and often 4 - 48 hours, at a temperature of 140 - 250'C, often raising the temperature from a value in the range 140 - 180C to a value in the range 190 - 250C during that time. A post cure ~-in the temperature range 140 - 190C may take 5 - 7 hours, whereas one in the range 220 - 250C may be accomplished in ., .
British Patent Speci~ication No. 115020~ describes the production of resins having repeating units of the formula ; - CH2 - R - CH2 - Ar -1 (C~2ArOH)n OH
wherein R is an aromatic hydrocarbon or aromatic hydrocarbon-oxy-aromatic hydrocarbon group, which optionally has inert ; substituents and Ar is the residue o~ a phenolic compound here-; inafter defined and n is O or 1. British Patent Specification No. 1305551 describes the curing of these resins with epoxides havinig 2 or more epoxy groups per molecule to form cured pro-ducts.
The above resins can be used for the production of sur~ace coatings and laminates having good chemical and high temperature ageing resistance and electrical properties.
15The coatlngs are prepared by dissolvlng the resin and a sultable curlng agent e.g. hexamethylene tetramine as in British Patent 1150203 or the epoxides as in British Patent 1~05551 in an organic solvent e.g. 2 - ethoxy ethanol or methyl isobutyl ketone, applying the solution to the sur~ace to be coated, evaporating the solvent and then curing the resultant coating ; to an infuslble product. I~ the coating ls to be used at a high temperature or if particular propertles are requlred of it, post curing e.g. at 160 - 250C may also be needed. We have found that the above resins tend to produce cured surface coat-ings showing ~Iclssingfl. Ciising is a well known surface coating phenomenon (see e.g. 'Palnt ~llm Defects' Manfred Hess, pub- -~
lished by Chapr.lan and Hall 2nd edltion 1955J p.436) and is associated wlth non-wettlng of the surface beln~ coated.
; Normally the resln laminates are prepared ~ia i~p~gnatiQn o~
glass cloth, or carbon fibre or asbestos cloth with a solutio~
of the resln ln an organic solvent e.g. methyl ethyl ketone.
Such laminates exhibit a wide range o~ utility. However, for certain appllcations lt may be desirable to incorporate additlonal materlals in the laminate, for example poly tetra-~luoroethylene or certain flame retardent materials, the latterespecially for epoxy curing agents. Hltherto, it has not been ~ound possible to produce completely satis~actory laminates ~rom resins incorporatlng such additional materials.
The above resins can also be used as adhesives but the ad-heslve strength of the cured resin is not very high because on curing blisters are ~ormed.
,. `3~ ' - ~ . : -: ` `
~ 8~76 ; - The present invention provides a resin composition which comprises . (a) a resin having repeating units of the formula 2~ n .. and preferably consists essentially of such repeating units, wherein Rl is a divalent or trivalent aromatic hydrocarbyl or divalent or trivalent aromatic hydrocarbyl-oxy-aromatic hydro-carbyl group, or inertly substituted derivatives thereof, and ,. 10 Ar is a residue formed by removal of 2 nuclear hydrogen atoms from a phenolic compound having 1-3 hydroxyl groups and at least 2 nuclear hydrogen atoms, and n is O or 1, and ; (b) an uncured or partially cured condensate of formaldehyde ,.;, s.~ and melamine, the weight ratio of resin to condensate being i 99:1 to 1:99.
~ The resin composition may also contain 0.5 to 100%
. by weight (based on the weight of the resin) of an inorganic . dispersing agent having at least one dimension less than . 100 mu and all dimensions less than 15u and stable to 150C.
;...... 20 The resin compositions of the invention may also contain a particulate material of particle size 0.2,u - 2 mm, ~i- preferably 1~ - 1 mm, and stable to 150C which is preferably s at least one of a flame retardent, lubricant, ... .
,. . .. .
; .
... .
',~ , .; - 3 -. . .
, .
. ~ .
l E
., 1~41~ 76 metal powder, and formaldehyde condensate with a nitrogen-ous compound (as hereinafter described).
We have found that the composition comprising resin and as dispersing agent finely divided silica of particle size 1 - 80 m,u, can be used with the curing agent to prepare a coating solution, which after application, evaporation ` of solvent and heating/curing, produces a coated layer in which the problem of cissing is greatly reduced if not elimin-ated. If desired the composition may also contain the particulate material.
The compositions of the invention comprising resin, the dispersing agent and curing agent and optionally the parti-culate material can be cured with decreased production of .
blisters in the cases when volatile materials are produced on curing e.g. with haxamethylene tetramine and thus can be used as adhesives with high adhesive strength.
"t The amount of inorganic dispersing agent is usually `~ !
0.5 - 20% (by weight based on the weight of the resin) when the resin composition is to be used for producing coatings ; 20 showing reduced cissing or for adhesives showing the cured ~ form reduced blistering, preferred amounts being 1 - 10%
i in both cases. When the resin composition also contains the particulate materials, an amount of 0.5 - 100~ (based on the weight of resin) of dispersing agent is used, the higher values being appropriate when the dispersion of resin, dispersing agent and particulate material is to be used as a "masterbatch" for subsequent dilution with further resin solution; amounts of dispersing agent in the region 1 - 20%
are preferred when the resin dispersion is to be used as such.
The amount of particulate material in the resin compo-: sition i~ usually 1 - 100% (by weight of resin), the higher ' .:
;
;-- ~ - 4 -. ~
. .
~: - .' .'. :
~`
~;~)4~3~76 :
values again being used when the composition is to be used , . I
as a masterbatch for subsequent dilution with more resin solution. Amounts of particulate material in the range 1 - 30% are suitable for dispersions to be used as such, the r.' preferred upper limit being dependent on the nature of the particulate material. The usual amounts of antimony oxide, chlorine and/or phosphorus containing organic flame retard-; ants and metal powders are respectively 5%, 10% and 25~.
, In the dispersions of the invention comprising resin, dispersing agents and particulate material (optionally with -curing agent) the amount of dispersing agent depends on the ~; nature and amount of the solvent and particulate material and on the degree of dispersion required.
The inorganic dispersing agent, which is stable to at least 150C, preferably to at least 200C, usually has a minimum dimension of at least lm~u. It is preferably finely i~ divided silica of average particle size 3 - 80m,u especially X. .. - ..
7 - 40m,u, e.g., the fumed colloidal silica sold under the .
i trade marks "AEROSIL" and "CAB-O-SIL", finely divided ;' 20 chrysotile asbestos e.g. of diameter about 25mp and length 5 to 10 ,u such as that sold under the trade mark "SYLODEX"
which may optionally be mixed with silica, and finely ; divided hydrous magnesium aluminium silicates e.g. organic derivatives of mont-morillonite with a platelike structure of thickness 2 to 4m,u and maximum dimension 0.5 to l~, such as that sold under the trade name "BENTONE".
Examples of the flame retardants are organic compounds containing halogen and/or phosphorus atoms such as poly- -halogenated organic compounds, preferably those in which the halogen is .,:, i~:
, ;
.... . .
~ 5 -,',"., ~.
..... .. . .
chlorine or bromine, and especially those in which the organic nucleus is an aromatic nucleus, e.g. decachlorobiphenyl, hexa-bromobenzene, hexachlorobenzene and tetrabromobisphenol A, and tris (bromopropyl) phosphate, tris (pentabromophenyl) phosphate and tris (dichloropropyl) phosphate. These compounds, which may be soluble in the resin solution, are used in con~unction ; with antimony o~ide, which is insoluble. Other flame retardants are metal borates e.g. borates of metals of Gp. 2 (of the Periodic Table published in Bull. Soc. Chim France January 1966 ?
such as zinc, calcium or barium. Antimony oxide may also be present in admixture with the borates.
The lubrlcant particulate materials may be homo polymers of tetrafluoroethylene (PTFE) and copolymers thereof with other fluorinated olefins of 3-6 carbon atoms e.g. perfluoropropylene, or may be inorganic in nature, such as graphite~ molybdenum di sulphide or metal salts of fatty acids of 8-20 carbon atoms, e.g.
; stearic acid, zinc and calcium stearates being preferred. In-corporation of the lubricant in the resin composition enables cured products e.g. bearings having a low coefficient of fric-; 20 tion to be obtained.
- The metal powder, that may also be the particulate material, ~-- may be aluminium powder or zinc dust. Metal powders are generally used when the resin, dispersing agen~ and metal ; powder is for use in surface coating applications, but could be used for producing laminates.
The particulate material can also be a formaldehyde condensate formed frrom f~r~alqehyde (or a compound yielding it in situ such . . , p a~^aJDr~n~/a~ ~C
D as poraformaldch~ or hexamine) and a nitrogenous compound Z Y
containing a N = C - NX2 group (or a group enolisable to said :. Z O
group such as a - N - C - NH2 group), wherein Y represents an oxygen, sulphur or nitrogen atom, and Z represents a hydrogen, carbon or oxygen atom or Y and Z together form a direct bond.
Preferably the nitrogenous compound contains at least 2 - NH2 : groups and preferably has 1-6J especially 1-~ carbon atoms.
~5 Examples of the nitrogenous compound are urea, melamine, thio ;~ urea, cyanamide, dlcyandiamide and guanidine. Such condensates ;~ which may be in the cured, partially cured or uncured form are well known and are described in, for example "Aminoplastics"
by C.P. Vale, published Cleaverhulme Press, London 1950. The preparation of the uncured condensates is described further below. The addition of these formaldehyde condensates to the resin compositions improves the electrical properties of the cured product.
. . .
48~76 The resin is preferably prepared, following the general proce~ure described in British patent specification No. 1150203, by reacting (1) an aralkyl ether of the general formula R' ` (-CH2OR)a and/or an aralkyl halide of the general formula R' (CH2X)a, wherein R' is a divalent or trivalent aromatic hydrocarbyl or aromatic hydro-carbyloxy aromatic hydrocarbyl radical,R' optionally containing inert substituents in the aromatic nucleus, R is an alkyl radical containing 1-5 carbon ;~ atoms, X is chlorine, bromine or iodine and _ has a value of ~ -2 or 3 with (2) a molar excess, normally of at least 1.3:1, preferably in the range of 1.4:1 to 2.5:1 of a phenolic compound or a phenolic compound and a non phenolic compound containing an aromatic nucleus. If a is 3 then n is 1 and a further ArOH
. ~ group may be bonded to R' through another methylene bridge.
. In these general formulae R' represents any divalent or i........... trivalent aromatic hydrocarbyl or aromatic hydrocarbyloxy .il aromatic hydrocarbyl radical, for example the m - or p-phenylene . radical, the diphenylene radical, the diphenylene oxide radical ";
,,~ ~0~, :~ ~ ' - -the radical ' or the radical .....
:., ~ 7 -, :.: -.. . .
`':
,., 1~41~76 ` Thus both mono nuclear, and fused and unfused di-and poly nuclear radicals may be represented by R', though mononuclear `` radicals are preferred because the cured products therefrom ~ have higher strength at high temperatures than those from di .` and polynuclear radicals. Preferably R' does not represent a -diphenylene or diphenylene oxide radical when the aralkyl halide is used to prepare the resin. The resin is preferably pre-pared from the aralkyl ether, especially ones in which R is an alkyl radical of less than 4 carbon atoms e.g. a methyl radical.
The preferred compounds for a reaction with the phenolic com-` pounds are those in which a has a value 2, particularly the p-xylylene dihalides for example p-xylylene dichloride and the ,~ p-xylylene dialkyl ethers for example p-xylylene - glycoldi -`~'` methylether.
,..;~
... .
,.. '; ~ .
' . ~
,,',, :-' ~. ~
.: ~
;~.,. , ~.
.. . .
", ~, '',i,~ ''' :
:~
~... I
,., ~ . ~
.,.,.
~:.,,. . : .
. .
. - 7a -: ~.
.,?, . :
:,''';
: .,;
~ E
, . .
.: ,.
4iY~76 .~
If desired the Rl radical may contain substituents, for ; example methyl radicals, attached to the aromatic nucleus, ,`; provided the said substituents are inert under the conditions of the reaction. In fact the presence of chlorine or fluorine atoms in some or all of the available positions in the aroma-tic nucleus has been found advantageous in that it leads to improved flame resistance in the resulting polymeric products~
Examples of such substituted aralkyl ethers and aralkyl halides, which may be employed according to this invention, are 2,3,5,6 -tetrachloro - 1,4 - di(chloromethyl) benzene and 2,~,5~6 -tetrachloro - l,4 - di(methoxy-methyl) - benzene.
~` The phenolic compound includes any compound or mixture of ;~` compounds derived from benzene and containing l to 3, preferably l or 2, hydroxyl radicals ~oined to the aromatic nucleus, there being a total of not more than ~ substituents attached to ring carbon atoms of the benzene nucleus apart from the one essen-tial hydroxyl group. Thus the phenolic compounds may be of formula OH
,........................ .
~ (R3)1 _ 3 .
where each R~ is hydrogen, hydroxyl, amino, alkyl of 1 to 8 carbon atoms, e.g. methyl, ethyl, isopropyl, tert, butyl or tert. octyl, phenyl and hydroxyphenyl alkyl e.g. hydroxy phenyl - methylene, - ethylene and - isopropylidene. Examples of these phenolic compounds are phenol, p - cresol, m - cresol, ; resorcinol, catechol, 4-methyloatechol, isopropyl catechol, diphenylol propane (bis 2,2- (4-hydroxy phenyl) propane), ; diphenylolethane, monoalkyl phenols such as p-ethylphenol, p-tert. butyl phenol and p-tert. octyl phenol, m - and p -phenyl phenol p - amino phenol, pyrogallol and phloroglucinol.
, Mixtures of the phenols can be used such as a monophenol with , .
a dihydric phenol e.g. resorcinol with phenol itself, or mix-tures of diphenols e.g. 4-methyl catechol and catechol and/or resorcinol such as that sold as a phenolic coal tar fraction.
Examples of the compound containing aromatic nuclei which may be mixed with the phenolic compound in the formation of the resin are dlphenyl - or dibenzyl - etherJ terphenyl, diphenyl-~`i amine, diphenyl sulphide diphenyl, anthracene, diphenylsulphone, ;~ triphenyl phosphate, octaphenylcyclotetrasiloxane, aryl sub~
stituted borazoles and metal complexes such as ferrocene.
The proportion of aromatic compound can vary within wide limits but i~ not sufficient to prevent satisfactory curlng of the ''., :
. ' .
` ` 1~48~7~
reaction product with the hardening agent. Further details of the aromatic compound and its modes of use in the reaction of - phenol and dihalide or diether are given in British Patent Specification No. 1150203.
The curing agent is a condensate of formaldehyde with melamine in the uncured or partly cured form. The condensates - are preferably made by reaction of one molar proportion of ~-~
; melamine with 1-10 molar proportions of formaldehyde (or formaldehyde yielding compound), especially 1:2 to 1:8 molar proportions, in neutral or alkaline conditions. The amount of curing agent needed for reaction with the resin in general depends on the nature of the curing agent, in particular on the number of free methylol groups on it and also the degree of curing desired. Thus less hexamethylol-melamine will generally be needed than trimethylolmelamine for equivalent curing. The resin is mixed with the formaldehyde condensate in a weight ratio of 1 - 99 : 99 - 1, preferably 50 - 95 : 50 - 5 and especially ;
, 65 - 85 : 35 - 15.
,.. ; .
The formaldehyde condensate in its uncured or partially ` 20 cured forms is used as a curing agent whether or not an i inorganic dispersing agent is also present. When the comp-`~ osition comprising resin (a) and condensate as curing agent is to be used as a moulding powder, the components can be dry mixed, formed into a moulding powder and subsequently moulded :,. -"
;' :
. .
, / .
`', ., I
l E
-- lo - lV48~76 under heat and pressure to rorm cured moulded articles. When the composition comprising resin (a) and condensate as curing agent is to be used ~or coating purposes or for impregnation in the production of laminates, it is preferred, but not essential, to incorporate the inorganic dispersing agent as well so that the liquid dispersion used for coating or dis-` persion may be as uni~orm as possible. The conditions for curing are the same as for hexamine curing. The use of the condensates or the nitrogenous compounds as curing agents en~
ables cured products with good electrical properties especially high arc and tracking resistance, and high heat resistance to be obtained.
The compositions of this invention may also contain in-organic fillers, e.g. asbestos flour, mica or chopped glass strands. The inorganic filler and resin will normally be present in a weight ratio of o.o5 r 1 to 4.0 : 1. Other in-gredients such as pigments, accelerators, and antistaining agents e.g. magnesium oxide, or titanium dloxide may also be present if desired.
- 20 The compositions of the ~nvention can be made by mixing the various components in any order, but it is convenien~ to add the curing agent last. me mixing can be carried out in any convenient method such as dry blending to form a powder for moulding (optionally with subsequent addition of organic solvent to make the desired liquid ~or coating and impreg-natlng purposes) or blending in solutions in an organic solvent to prepare the liquid directly. The solvent may be a dialkyl ketone o~ 3-8 carbon atoms e.g. methyl isobutyl ketone, methyl ~, ethyl ketone, or methylisoamyl ketone, isophorone, diacetone i': 30 alcohol,a cycloalkyl ketone of 5-7 carbon atoms e.g. cyclo-hexanone, an alkoxy alkanol with 1-6 carbon atoms in the alkoxy group and 2-7 carbon atoms ln the alkanol group such as 2 - ethoxyethanol, alkyl ethers thereof with 1-6 carbon atoms in the alkyl group e.g. the methyl ether,esters o~ the ~5 alkoxy alkanols with alkanoic acids of 2-6 carbon atoms e.g.
the acetate, any Or whlch solvents can be (in an amount suf-ricient to maintain the resin in solution) mixed with an ` aromatic hydrocarbon preferably a monocyclic one of 6-12 carbon atoms such as benzene, toluene or xylene or an aliphatic ~; 40 hydrocarbon such as white spirit or solvent naphtha or an al~anol e.g. o~ 1 to 6 carbon atomsJ such as methanol, ethanol - or n - butanol. me resin is usually present in the organi~
solvent solutions in an amount o~ 5 - 90~ preferably 20 - 65 e.g. 20 - 50~ by weight. The mixing can be carried out at a 4~76 low temperature e.g. 20 - ~0C and ~he mixture stored until required, but the mixing of the curing agent with the remainder of the components is usually carried out at a higher tempera-ture e.g. about 60 C for several hours e.g. 1 - 4 hrs. and then the mixture cooled to room temperature and stored until required.
The liquid dispersed mixture of resin, dlspersing agent (if present), particulate material (if present), solvent and curing agent (and other additives if present) can be used as a coating solution or as an lmpregnant for the production of laminates.
me solvent from the liquid dispersed mixture can also be evaporated and the residual product used as a moulding powder; this technique ls pre~erred for the production of moulding powders containing long fibres, which may be broken in the dry mixing method.
The compositions of the invention are cured by heating usually at above 70C and preferably over 100C e.g. 150 -;~ 175C. Post curing if needed is usually carried out at 160 C -250C. The time needed for post-curing varies according to the properties of the desired product, and the temperature of use ; of that product.
For the use of the compositions of the invention for coating, the mixture of resin9 dispersing agent (if present), curing agent and solvent (together with any other additives) can be applied by any means to the surface to be coated e.g.
by painting, spraying or lmmersion. Normally the surface will be of metal e.g. ~errous metal such as mlld steel but other substrates suoh as wood, plastic material or inorganic mater-, ials such as porcelain or cement can be coated, if desired.
~0 After coating the solvent is evaporated and the layer cured.
~hen the dispersing agent is finely divided silica, the curqd layer shows little or no "cissing'.
i In the use of the compoæitions of the invention as adhesives the mixture of resin, dispersing agent, curing agent and sol-vent, (together with any other additives) can be applied to one or both of the surfaces to be adhered together by any means e.g. painting, spraying or immersion. Examples of suitable surfaces are those of metals e.g. ferrous metal such as mild ~teel but other substrates such as plastics materials e.g. those described in British Patent 115020~, optionally with reinforcement e.g. glass or asbestos fibres, or inorganic materials such as porcelain or cement can be used. After the applications, the solvent is evaporated, the surfaces brought together and the combination of surfaces and intervening layer .,, '' .
,, : ' ~ ' .
1~ 8~
cured. Because of the reduction in the number and/or size of blisters produced, the bond formed by the combination has high strength.
In the use of the compositions of the invention for making laminates, the liquid mixture is applied to the laminate base. Suitable laminate bases are glass cloth or carbon ~ibre agglomerates although other fibrous materials such as asbestos cloth may also be employed if desired.
Such materials are impregnated with the dispersed mixture as described above and then dried. Typically the fibrous base is passed through a bath of the resin dispersion.
The fibrous material into which the resin has been , . .
impregnated is then subjected to a precure heat treatment at about 140C~ often for about 10 minutes. The laminates are then pressed at a tempPrature above 160C often in the range 170 to 190C at a pressure of from 7 to 105 kg/cm2, although pressures above 35 kgjcm2, often of about 70 kg/cm2 are normally employed. Normally pressing will be carried out for a period of at least 1/2 hour, often for about an ^ 20 hour, depending upon the conditions of temperature and pressure employed.
; For optimum results the laminates are subsequently ,.
post cured. The temperature and time employed for the pos-t cure operations are dependent upon each other. For example a post cure in the temperature range 140 - 190 C may take ;~ up to 7 hours whereas one in the range 220 - 250 C may be accomplished in five hours. However, it is normally desirable that the material is heated to a temperature at least in the range 190C - 220C.
. .
.
,' ''~ ' lV4~76 , The invention is illustrated in the following Examples:
Example I
Resin A
An aralkylene phenol resin was made by reacting 705g (7.5 moles) of phenol and 830g (5 moles) of p-xylylene dimethyl ether (technical grade) in the presence of lml. of diethyl sulphate as catalyst. On heating to 130 - 200C
methanol was lib~rated and distilled out. The product on '; cooling, was a red brown solid having a softening point of ,~ 10 97& . -Resin B
126g (1 mole) of melamine and 225mls (3 moles) of a 40% formalin solution were mixed together and a few drops :~ of dilute sodium hydroxide were added to make the mixture .
slightly alkaline. The resultant solution was heated to ~ 75& with stirring and on cooling a white pre~ipitate was `;~ formed. This was filtered off and dried-to obtain a white powder, trimethylol melamine nominally.
Resin C
7.5gms of resin A were mixed th~roughly in a powdered state with 2.5gms of resin B. The mixture was put into an aluminium dish and placed in an oven at 200C. A hard infusible, insoluble mass was formed.
240gms of resin A were dissolved in a mixture of 240gms .. . . . . .
of ethyl methyl ketone and 80g of industrial methylated .:: . .
spirits. To this solution was added 80gms of resin B and ... .
6gms of fumed silica and these were dispersed using a high speed mixer. The resultant mixture was used to impregnate glasscloth "MARGLASS" (trade mark) 116T/P705 and the pre-preg produced was precured for 10 minutes at 135 C. This was cut into 25cm x 25cm squares and pressed into a laminate , ;
; - 13 -.~:
. .
'.,~
.. .. . .
- `` 1~48~76 at 175C,t70 kg/cm for 1 hour. The laminate produced was ~.. post-cured from 140 to 250C over 23 hours and had the .
. following flexural strengths .. Flexural measured strength at 20C 5700 kg/cm2 150C 2680 " "
~ 200C 1300 :s 250C 1016 " "
~'`' ' .
,. .
,;~, ~ .
.'1 ' . ' .
, .
. .
., ~ .
,.~.
.
.
, . . .
.,~, .
.
....
.
;,, .
, . . , .~:
- 14 - .
`;;:
,: .
.. :, . . ..
.. .
::; .
: .:
1q~4~3~76 ` SUPPLEMENTARY DISCLOSURE
,,'' ' :
In the main disclosure are described resin compositions which comprise a resin having repeating units of the formula .,i .
~H R' CH Ar (CH2ArOH)n OH
and an uncured or partly cured condensate of formaldehyde and melamine. The formaldehyde condensate acts as a curing agent for the resin to give cured products with good electrical properties and high heat resistance.
; We have found that if the weight of the condensate is 55 - 90% of the combined weight of resin and condensate, . , .
then the cured products have good arc and track resistance and : strength at high temperatures which may be accompanied by high heat resistance as well.
The compositions with the higher amounts of condensate comprise (a) a resin having repeating units of the formula -CH2 - R' - CH - Ar I
- (CH2ArOH)n OH
terminated with ArOH groups wherein R' is a divalent or trivalent ~ 20 aromatic hydro-carbyl or divalent or trivalent di(aromatic ; hydrocarbyl) oxy group, which optionally has at least one inert substituent and Ar is a residue formed by removal of two nuclear hydrogen atoms from a phenolic compound having 1 - 3 hydroxyl groups and at least two nuclear hydrogen atoms in ortho . ,, and/or para positions to a hydroxyl group, and n is 0 or 1 and ;` (b) a condensate formed from formaldehyde ( or a compound ~ yielding it in situ such as paraformaldehyde or hexamethylene,.............. .
tetramine) and melamine, said condensate being in an uncured - or partially cured form and provided 55 - 90% by weight of the total weight of resin and condensate.
:, . .~ . .;
: .
,,;
` i~48~76 ` The condensates are preferably made by reaction of "' one molar proportion of melamire with 1.2 - 10 molar proportions of formaldehyde (or less preferred, the equivalent amount of formaldehyde yielding compound) especially 1:2 to 1:8 molar ~ proportions, in neutral or alkaline conditions. The condensate : is uncured or partially cured, usually with not more than five repeat units derived from the nitrogenous compound. Preferably it is uncured with one structural unit derived from melamine and at least two hydroxymethyl groups attached to nitrogen atoms.
The two hydroxymethyl groups may be attached to the same or different nitrogen atoms. Preferably the condensate contains hydroxy methyl groups attached to nitrogen atoms in an average number from two, (and preferably from 2.5) to the maximum number of hydrogen atoms attached to nitrogen ato~s in the melamine. The condensate preferably contains 2 to 6, usually ; an average of 2.5 to 6, and especially 3 or 6 (as in trimethyl-~ olmelamine and hexamethylolmelamine) hydroxymethyl groups. An - average of 2.5 hydroxy methyl groups per molecule of melamine means that, for example, the condensate is a 1:1 molar mixture of a condensate with 2-, and a condensate with 3-hydroxymethyl ` groups per molecule of melamine.
~ The amount of formaldehyde condensate is 55 - 90%
; by weight of the total weight of resin and condensate. Amounts ; .:
i ` of 58 - 74%, eg. 60 - 70% are preferred as these amounts give cured products with high strength at high temperatures and , ~ . , moderate retention of strength after aging at high temperatures but coupled with a moderate comparative tracking index. Amounts j of 74 - 90%, eg. 80 - 90%, are used if a much higher comparative '!, tracking index of the cured products is wanted.
The resin has repeating units of formula '~''"', .., .
.. 31~
g~i76 - CH2 - R' CH - Ar -:~ - (CH2ArOH)n OH
and is terminated by ArOH groups. Preferably the resin contains substantially only units derived from ArOH and units of skeletal structure -- -- - C - R' - C -(- C ~)n The resin is preferably made,following the general procedure described in British Patent No. 1150203,by reacting (1) an aralkyl ether of the general formula R'(CH2OR)a and/or aralkyl halide of the general formula R'(CH2X)a, wherein R', R, a and X are as defined above, with a molar excess of a phenolic compound, or a mixture thereof with a nonphenolic compound containing an aromatic nucleus. While R' is preferably an unsubstituted aromatic hydrocarbyl group, especially a m-; or p- phenylene group, if desired the R' radical may contain at least one substituent attached to the aromatic nucleus, which substituent is an alkyl group of 1 to 6 carbon atoms, e.g.
a methyl group a phenyl group or a halogen atom, e.g. a chlorine or bromine atom. These substituents are inert under the con~
ditions of the reaction. In fact the presence of chlorine or ) fluorine atoms in some or all of the available positions in the aromatic nucleus is advantageous in that it leads to improved flame resistance in the resulting polymeric products. Examples of such substituted aralkyl ethers and aralkyl halides, which may be employed according to this invention, are 2, 3, 5, 6 -; tetrachloro - 1, 4 - di (chloromethyl) benzene and 2, 3, 5, 6 -~" tetrachloro - 1, 4 - di(methoxy-methyl) - benzene.
:,, ~ The phenolic compound is any compound or mixture of ..
compounds derived from benzene and containing 1 to 3, preferably ~- 1 or 2, hydroxyl radicals joined to an aro~atic nucleus, at least two of the ortho and para positions to a hydroxyl :- .
r ~ ~ ~ 17 ~
~, .
" 1q~48~i76 :.
group b~ing unsubstituted and any non-hydroxlic substituents being inert under the conditions of the reaction. Thus the phenolic compounds may be of formula OH
~ (R3)1-3 where each R3 is hydroxyl, alkyl of 1 to 8 carbon atoms, e.g., methyl, ethyl, isopropyl, tertiary butyl or tertiary octyl, halogen e.g. chlorine, nitro, phenyl and bis(hydroxyphenyl)-alkyl, e.g. bis(hydroxy phenyl)- methylene, -ethylene and -isopropyl-idene. Preferably the phenolic compounds contain only onearomatic ring. Examples of these phenolic compounds are phenol, p - cresol, m - cresol, resorcinol, catechol, 4 - methyl-catechol, isopropyl catechol, d1phenylol propane (bis 2,2- (4-hydroxy phenyl) propane), diphenylolethane, monoalkyl phenols such as p-ethylphenol, p-tertiary butyl phenol and p-tertiary .:
octyl phenol, m - and p - phenyl phenol, pyrogallol and phloroglucinol. A mixture of phenol and beta naphthol as des-cribed in our British Patent Specification No. 1363531 may be used. Mixtures of the phenols can be used such as a mono-phenol with a dihydric phenol, e.g. resorcinol with phenol itself, or mixtures of diphenols, e.g. 4-methyl catechol and ; catechol and/or resorcinol, such as that sold as a phenolic coal tar fraction. Preferably these particular mixtures or phenol itself resorcinol, or catechol are used.
The aralkylene compound of formula R'(CH2OR)a or ; R(CH2X)a is preferably substantially pure usually with at least 90% by weight of the expected compound, but technical grade materlals may be used. Thus technical grade p-xylylene glycol dimethyl ether can contain 65 - 90% of the expected 30 compound, 0.1 - 5% of p-methoxymethyl toluene, 0.1 - 10% of , - 18 -"', ,. . . . .
-..... . : - . : :
1~48~76 ~
p-tolualdehyde dimethyl acetal and 10 - 35% of p-methoxymethyl-benzaldehyde dimethyl acetal and small amounts of other im-purities. The amount of the acetal includes any of the corres-ponding aldehyde present.
The reaction to form the resin is carried out with one mole of aralkylene compound and a molar excess of the phenolic compound or mixture thereof with the aromatic com-pound. Preferably at least 1.3 moles of phenolic compound ~-(or mixture) per mole of aralkylene compound are used. From 1.3 to 3 moles of the phenolic compound are suitably employed for every mole of the aralkylene compound. When the molecular proportion falls below the specified 1.3:1 ratio and approaches ; 1:1 the reaction mixture exhibits an increased tendency to gel prematurely. When in the aralkylene compound a is 2 and the . , ~ratio of phenol to compound is greater than 2.5, the resulting ~-.7 products become more difficult to cure. Polymeric products having the highest softening points are obtained when the ratio of the phenolic compound to aralkylene compound is at the low end of the specified range. Preferably when a in the compound is 2 the phenolic compound is employed in a ratio of 1.3:1 to 2:1 e.g. 1.3 to 1 to 1.7 to 1, especially 1.4 to 1.6:1. When a in the compound is 3, the phenolic compound is preferably employed in a ratio of 2:1 to 3:1 e.g. 2.5:1 to 3:1.
The compositions of the invention are cured by heat-ing, usually at above 70C and preferably 100 - 180C, e.g.
~;~ 150 - 180C. Post curing may also be carried out, usually :~ .
, initially at 60 - 100C for 4 - 24 hours, and then at 160 -250C. The time needed for post curing varies according to .~i . .
~ the properties of the desired product, and the temperature of ,~ 30 use of that product; examples of times of curing at 100 - 180C
,: ., are 0.5 - 48 hours, e.g. 0.5 - 10 hours at 150 - 180C. The ,, , 19 ' !
: ' . ." . : ~ .
. .
,.'. '. ` ~' ' : .
'; -1~)41~i76 cured articles are usually in the form of moulded products or laminates.
In the production of laminates, a solution or dis-persion of the resin and condensate is used to impregnate a fibrous laminate base. The fibrous material into which the resin has been impregnated is usually then subjected to a precure heat treatment at 100 - 160C, often at 130 - 140C for 5 - 20 minutes, e.g. for about 10 mins. In the prepregs formed ` the resin and condensate have partly reacted. A stack of the prepregs is then pressed at a temperature above 160C, often in the range 170 - 190C at a pressure of from 100 to 1,500 psi, although pressures above 500 psi, often of about 1,000 psi are normally employed. Normally pressing will be carried out for a period of at least 1/2 hour, and generally up to 2 hours, often for about an hour, depending upon the conditions of temperature and pressure employed.
For optimum results the laminates are subsequently post cured, e.g. by heating outside the press (as in air circulating oven). The temperature and time employed for the post cure operations are dependent upon each other, and on the ; use of the product and the degree of post cure. Usually the post cure is at 60 - 100C for 4 - 24 hours, e.g. 12 - 24 hours at 80 - 100C, and then for at least 3 hours, and often 4 - 48 hours, at a temperature of 140 - 250'C, often raising the temperature from a value in the range 140 - 180C to a value in the range 190 - 250C during that time. A post cure ~-in the temperature range 140 - 190C may take 5 - 7 hours, whereas one in the range 220 - 250C may be accomplished in ., .
3 - 5 hours. However it is normally desirable that the i 30 material is heated to a temperature in the range 190 - 220C.
., :
The cured products with good comparative tracking ... .
. .
. .
.
- - ~
1~48676 index may be used in electrical insulation, e.g. in insulators for external uses or in electric motors.
The invention is illustrated in the following ;
Examples.
The technical grade p-xylylene glycol dimethyl ethers used in the Examples are products containing 65 - 75% p-;xylylene glycol dimethyl ether, 0.5 - 3~ p-methoxymethyltoluene, i ~ . :. -; 0.5 - 5% p-tolualdehyde dimethyl acetal, 10 - 25% of p-methoxy-methylbenzaldehyde dimethyl acetal and small amounts of other - 10 p-xylenes substituted in the side chains with methoxy groups.
The amount of acetal includes any of the corresponding aldehyde present. ~`
Example 2 and Comparative Example 1 Condensate A
; ,. , '252 g (2 moles) of melamine were added to 429 g ,...................................................................... .
(5 moles) of a 38% formaldehyde solution and the resultant ;' -mixture was heated until a clear solution was obtained at 70C.
.;. .
Then, 127 g of 2-ethoxyethanol was added to give a 50% solution .,~
of melamine condensate (nominally a mixture of di and tri-methylolmelamines).
The following solution formulations were prepared:-~^~ Comp. Ex. 1. 2 Solutions A B
-Aralkyl-phenol resin from p-xylylene glycol dimethyl ether tech (40 mol.%) and phenol (60 mol.%) prepared as ~'. described in BP1150203.
Softening point 88C. 250 g 165 g .';' !, " Solution of condensate A. 500 g 660 g ;$' 30 2 - ethoxyethanol 365 g 275 g , ;;~ Concentration of condensate (based on total weight of condensate and resin). 50% 66.7%
.,~.,. . ~.
~ . .
~. 1 ,.: ,:
.,:: .
'' ` 1~48f~76 The solutions A and B were impregna~ed into Marglass 116T/P705 glasscloth and then the impregnated glasscloth pre-cured at a temperature at 120C and 115C respectively each for 10 minutes. Laminates were made from the prepregs pro-duced by pressing for 1 hour at 175C and 1,000 psi, and then post curing in an air circulating o~en for 16 hours at 90C
and 6 hours from 140 - 200C. The resin contents of the laminates A and B prepared in this way were 31.7%, and 31.7 respectively.
After post curing, flexural strength measurements were made on the laminates at about 20C, 150C and 200C
before and after heat aging at 200C. The results obtained ~ .
were as follows.
Flexural strengths at 20C (psi) A B
initial 38,600 -40,100 after 24 hrs. at 200C 40,000 32,900 ' "48 hrs. " 43,000 31,900 "100 hrs. " 36,800 27,600 "250 hrs. " 20,000 17,800 , "500 hrs. " 10,000 11,000 . . .
"750 hrs. " D.L. 8,900 " 1000 hrs. " D.L. D.L.
D.L. means delaminated, i.e. the sample split, an indication ;~
of poor strength.
Flexural strengths at 150C (psi) A B
initial 41,500 33,700 after 24 hrs. at 200C 31,600 23,200 " 48 hrs. " 44,600 25,300 " 100 hrs. " 32,200 23,000 : ' .
.~
". 1048~76 Flexural strengths at 150C (psi) (cont'd) A B -after 250 hrs. at 200C 15,500 14,400 ; " 500 hrs. " D.L. 10,500 , . " 750 hrs. " D.L. 8,100 " 1000 hrs. " D.L. D.L.
Flexural strengths at 200C (psi) A B
,~ 10 initial 39,300 26,100 ,;
, after 24 hrs. at 200C 35,200 29,600 ' "48 hrs. " 35,000 34,100 "100 hrs. " 32,300 23,400 ~` "250 hrs. " 13,800 13,800 "500 hrs. " 8,800 8,800 "750 hrs. " D.L. 9,900 n 1000 hrs. 1! D.L. D.~.
Thus the initial strength at low and high temp-eratures of laminates is adequate and a significant per-~, 20 centage of that strength is retained on aging at 200C.
.. . . .
Condensate Resin B
378 gms (3 moles) of melamine were added to 772 .,,~: .
,~ gms (9 moles) of a 38% w/v formaldehyde solution and the ~' resultant mixture was heated until a clear solution of tri-methylol melamine was obtained at a~out 70C. At this point -1150 gms of 2 - ethoxyethanol were added with stirring and ~` the solution was cooled.
Example 3 and Comparative Example 3 .~., . :
,~ Resin A
:.~ . .
282 g (3 moles) of phenol were mixed with 249 (1.5 '; moles) of technical p-xylylene glycol dimethylether in the presence of 0.2 mls of diethyl sulphate as catalyst. The mixture was heated to 135 - 180C and the methanol formed by - reaction was distilled out. The product was a red-brown semi-solid.
The following solutions were prepared:-Comparative Ex. 2 Ex. 3 r Solution _ _ aralkyl phenol resin A362 g 181 g solutio~ of condensate A 362 g 724 g 2-ethoxyethanol 436 g 255 g These solutions have concentrations of 33.3% and 66.7% of the condensate based on the total solids content. Glasscloth laminates were made from the solutions as in Example 2 with precure conditions of 10 mins. at 134C for C and at 140C
for D.
The resin contents of the laminates were 35.0% and 30.0% respectively. The laminates were post cured as des- -cribed in Example 2. Their flexural strengths after heat aging at 200C were measured.
Laminate CFlexural strengths (psi) :. .
initial 85,600 30,70015,400 after 24 hrs. at 200C75,500 50,40026,000 " 48 hrs. " 85,900 60,00038,800 " 100 hrs. " 88,300 60,00035,600 " 250 hrs. " 78,000 61,70054,100 Laminate D Flexural strengths (psi) initial 45,000 44,20043,200 after 24 hrs. at 200C43,600 44,50047,600 " 48 hrs. " 43,500 31,40045,200 " 100 hrs. " 48,800 39,00041,300 1~48f~76 Flexural strengths (psi) (cont'd) after 250 hrs. at 200C 21,300 18,600 18,600 These results show that the laminate D (from 66.7~
condensate) has adequate strength and some retention of that strength at high temperatures, though not as much as that of laminate C (from 33.3% condensate).
Examples 4 to 6 and Comparative Examples 3 and 4 Preparation of Trimethylolmelamine .
378 g (3 moles) of melamine were added to 772 g (9 moles) of a 38~ w/v formaldehyde solution and the resultant mixture was heated until a clear solution was obtained at about 70C. On cooling to room temperature solid trimethyl-olmelamine precipitated. This was filtered and dried in an air-circulating oven at 60C.
The following mixes were prepared:-Examples: Comp. Ex. ~ Comp. Ex. 4 4 5 6 Mixes: E F G H J
Aralkyl-phenol resin (as used in Example 2). 80g 40g 32g 24g 16g Trimethylolmelamine (TMM) - 40g 48g 56g 64g Silica 120g 120g120g120g 120g Magnesium oxide 2.6g 2.6g2.6g2.6g 2.6g Zinc stearate 3.2g 3.2g3.2g3.2g 3.2g Hexamine 10g The amount of trimethylolmelamine in E to J is 0, 50, 60, 70 and 80% respectively, based on the total weight of aralkyl-phenol resin and trimethylolmelamine. -E was milled for 12 minutes at 120C. The rest were milled for 2 minutes at 120C.
Discs were moulded from each of the mixes ~sing a pressure o~ 1,000 psi for 30 minutes, at 175C. The discs 1~;)4~i67~i were post cured by heating at 90C for 16 hours and from 140C
to 200C over 9 hours.
The comparative kracking index (CTI) was obtained for each disc according to BS.3781.
The results were as follows:
Disc from Mix. CTI
Thus mixes G and H, having 60 and 70% respectivel~
condensate give higher CTI values than F with 50~ TMM, but the CTI from mixture J with 80~ TMM is highest. -.
Examples 7 - 10 and Comparative Examples 5 and 6 50% solutions of aralkylene-phenol resin as used in Example 2 and 50% solutions of trimethylolmelamine (TMM) Condensate B, each in 2-ethox~ ethanol, were mixed in different proportions to give a series of solutions K - Q. Each of the 20 solutions was heated in an aluminium dish at 130C for 30 minutes to evaporate the solvent and cause curing and then heated at 250C for two hours in complete the cure. Each specimen produced was weighed and then re-weighed after being heated for 24 hours at 250C. The weight loss on the aging as a percentage of the original weight was as follows.
Example Solution % Resin % TMM ~ Weight Loss Comp. Ex. 7 K 50 50 4.0 Ex. 7 L 40- 60 4.7 Ex. 8 M 30 70 6.2 Ex. 9 N 20 80 8.5 Ex. 10 P 10 90 9.3 Comp. Ex. 8 Q 0 100 9.8 .
~ - 26 -. - : . . .
1~48676 These results and those of Examples 4 - 6 show that with 60 - 7~ TMM, the cured products have a moderate com-parative tracking index and a moderate resistance to high temperature aging, while with 80 - 90~ T~$ the CTI is large but the resistance to aging is poorer. .
. - 26a -
., :
The cured products with good comparative tracking ... .
. .
. .
.
- - ~
1~48676 index may be used in electrical insulation, e.g. in insulators for external uses or in electric motors.
The invention is illustrated in the following ;
Examples.
The technical grade p-xylylene glycol dimethyl ethers used in the Examples are products containing 65 - 75% p-;xylylene glycol dimethyl ether, 0.5 - 3~ p-methoxymethyltoluene, i ~ . :. -; 0.5 - 5% p-tolualdehyde dimethyl acetal, 10 - 25% of p-methoxy-methylbenzaldehyde dimethyl acetal and small amounts of other - 10 p-xylenes substituted in the side chains with methoxy groups.
The amount of acetal includes any of the corresponding aldehyde present. ~`
Example 2 and Comparative Example 1 Condensate A
; ,. , '252 g (2 moles) of melamine were added to 429 g ,...................................................................... .
(5 moles) of a 38% formaldehyde solution and the resultant ;' -mixture was heated until a clear solution was obtained at 70C.
.;. .
Then, 127 g of 2-ethoxyethanol was added to give a 50% solution .,~
of melamine condensate (nominally a mixture of di and tri-methylolmelamines).
The following solution formulations were prepared:-~^~ Comp. Ex. 1. 2 Solutions A B
-Aralkyl-phenol resin from p-xylylene glycol dimethyl ether tech (40 mol.%) and phenol (60 mol.%) prepared as ~'. described in BP1150203.
Softening point 88C. 250 g 165 g .';' !, " Solution of condensate A. 500 g 660 g ;$' 30 2 - ethoxyethanol 365 g 275 g , ;;~ Concentration of condensate (based on total weight of condensate and resin). 50% 66.7%
.,~.,. . ~.
~ . .
~. 1 ,.: ,:
.,:: .
'' ` 1~48f~76 The solutions A and B were impregna~ed into Marglass 116T/P705 glasscloth and then the impregnated glasscloth pre-cured at a temperature at 120C and 115C respectively each for 10 minutes. Laminates were made from the prepregs pro-duced by pressing for 1 hour at 175C and 1,000 psi, and then post curing in an air circulating o~en for 16 hours at 90C
and 6 hours from 140 - 200C. The resin contents of the laminates A and B prepared in this way were 31.7%, and 31.7 respectively.
After post curing, flexural strength measurements were made on the laminates at about 20C, 150C and 200C
before and after heat aging at 200C. The results obtained ~ .
were as follows.
Flexural strengths at 20C (psi) A B
initial 38,600 -40,100 after 24 hrs. at 200C 40,000 32,900 ' "48 hrs. " 43,000 31,900 "100 hrs. " 36,800 27,600 "250 hrs. " 20,000 17,800 , "500 hrs. " 10,000 11,000 . . .
"750 hrs. " D.L. 8,900 " 1000 hrs. " D.L. D.L.
D.L. means delaminated, i.e. the sample split, an indication ;~
of poor strength.
Flexural strengths at 150C (psi) A B
initial 41,500 33,700 after 24 hrs. at 200C 31,600 23,200 " 48 hrs. " 44,600 25,300 " 100 hrs. " 32,200 23,000 : ' .
.~
". 1048~76 Flexural strengths at 150C (psi) (cont'd) A B -after 250 hrs. at 200C 15,500 14,400 ; " 500 hrs. " D.L. 10,500 , . " 750 hrs. " D.L. 8,100 " 1000 hrs. " D.L. D.L.
Flexural strengths at 200C (psi) A B
,~ 10 initial 39,300 26,100 ,;
, after 24 hrs. at 200C 35,200 29,600 ' "48 hrs. " 35,000 34,100 "100 hrs. " 32,300 23,400 ~` "250 hrs. " 13,800 13,800 "500 hrs. " 8,800 8,800 "750 hrs. " D.L. 9,900 n 1000 hrs. 1! D.L. D.~.
Thus the initial strength at low and high temp-eratures of laminates is adequate and a significant per-~, 20 centage of that strength is retained on aging at 200C.
.. . . .
Condensate Resin B
378 gms (3 moles) of melamine were added to 772 .,,~: .
,~ gms (9 moles) of a 38% w/v formaldehyde solution and the ~' resultant mixture was heated until a clear solution of tri-methylol melamine was obtained at a~out 70C. At this point -1150 gms of 2 - ethoxyethanol were added with stirring and ~` the solution was cooled.
Example 3 and Comparative Example 3 .~., . :
,~ Resin A
:.~ . .
282 g (3 moles) of phenol were mixed with 249 (1.5 '; moles) of technical p-xylylene glycol dimethylether in the presence of 0.2 mls of diethyl sulphate as catalyst. The mixture was heated to 135 - 180C and the methanol formed by - reaction was distilled out. The product was a red-brown semi-solid.
The following solutions were prepared:-Comparative Ex. 2 Ex. 3 r Solution _ _ aralkyl phenol resin A362 g 181 g solutio~ of condensate A 362 g 724 g 2-ethoxyethanol 436 g 255 g These solutions have concentrations of 33.3% and 66.7% of the condensate based on the total solids content. Glasscloth laminates were made from the solutions as in Example 2 with precure conditions of 10 mins. at 134C for C and at 140C
for D.
The resin contents of the laminates were 35.0% and 30.0% respectively. The laminates were post cured as des- -cribed in Example 2. Their flexural strengths after heat aging at 200C were measured.
Laminate CFlexural strengths (psi) :. .
initial 85,600 30,70015,400 after 24 hrs. at 200C75,500 50,40026,000 " 48 hrs. " 85,900 60,00038,800 " 100 hrs. " 88,300 60,00035,600 " 250 hrs. " 78,000 61,70054,100 Laminate D Flexural strengths (psi) initial 45,000 44,20043,200 after 24 hrs. at 200C43,600 44,50047,600 " 48 hrs. " 43,500 31,40045,200 " 100 hrs. " 48,800 39,00041,300 1~48f~76 Flexural strengths (psi) (cont'd) after 250 hrs. at 200C 21,300 18,600 18,600 These results show that the laminate D (from 66.7~
condensate) has adequate strength and some retention of that strength at high temperatures, though not as much as that of laminate C (from 33.3% condensate).
Examples 4 to 6 and Comparative Examples 3 and 4 Preparation of Trimethylolmelamine .
378 g (3 moles) of melamine were added to 772 g (9 moles) of a 38~ w/v formaldehyde solution and the resultant mixture was heated until a clear solution was obtained at about 70C. On cooling to room temperature solid trimethyl-olmelamine precipitated. This was filtered and dried in an air-circulating oven at 60C.
The following mixes were prepared:-Examples: Comp. Ex. ~ Comp. Ex. 4 4 5 6 Mixes: E F G H J
Aralkyl-phenol resin (as used in Example 2). 80g 40g 32g 24g 16g Trimethylolmelamine (TMM) - 40g 48g 56g 64g Silica 120g 120g120g120g 120g Magnesium oxide 2.6g 2.6g2.6g2.6g 2.6g Zinc stearate 3.2g 3.2g3.2g3.2g 3.2g Hexamine 10g The amount of trimethylolmelamine in E to J is 0, 50, 60, 70 and 80% respectively, based on the total weight of aralkyl-phenol resin and trimethylolmelamine. -E was milled for 12 minutes at 120C. The rest were milled for 2 minutes at 120C.
Discs were moulded from each of the mixes ~sing a pressure o~ 1,000 psi for 30 minutes, at 175C. The discs 1~;)4~i67~i were post cured by heating at 90C for 16 hours and from 140C
to 200C over 9 hours.
The comparative kracking index (CTI) was obtained for each disc according to BS.3781.
The results were as follows:
Disc from Mix. CTI
Thus mixes G and H, having 60 and 70% respectivel~
condensate give higher CTI values than F with 50~ TMM, but the CTI from mixture J with 80~ TMM is highest. -.
Examples 7 - 10 and Comparative Examples 5 and 6 50% solutions of aralkylene-phenol resin as used in Example 2 and 50% solutions of trimethylolmelamine (TMM) Condensate B, each in 2-ethox~ ethanol, were mixed in different proportions to give a series of solutions K - Q. Each of the 20 solutions was heated in an aluminium dish at 130C for 30 minutes to evaporate the solvent and cause curing and then heated at 250C for two hours in complete the cure. Each specimen produced was weighed and then re-weighed after being heated for 24 hours at 250C. The weight loss on the aging as a percentage of the original weight was as follows.
Example Solution % Resin % TMM ~ Weight Loss Comp. Ex. 7 K 50 50 4.0 Ex. 7 L 40- 60 4.7 Ex. 8 M 30 70 6.2 Ex. 9 N 20 80 8.5 Ex. 10 P 10 90 9.3 Comp. Ex. 8 Q 0 100 9.8 .
~ - 26 -. - : . . .
1~48676 These results and those of Examples 4 - 6 show that with 60 - 7~ TMM, the cured products have a moderate com-parative tracking index and a moderate resistance to high temperature aging, while with 80 - 90~ T~$ the CTI is large but the resistance to aging is poorer. .
. - 26a -
Claims (37)
1. A resin composition which comprises (a) a resin having repeating units of formula wherein R1 is a divalent or trivalent aromatic hydrocarbyl or divalent or trivalent aromatic hydrocarbyl-oxy-aromatic hydrocarbyl, or inertly substituted derivatives thereof, Ar is a residue formed by removal of two nuclear hydrogen atoms from a phenolic compound having 1 - 3 hydroxyl groups and at least two nuclear hydrogen atoms, and n is 0 or 1, and, (b) an uncured or partially cured condensate of formaldehyde and melamine, the weight ratio of resin to condensate being 99 : 1 to 1 : 99.
2. A composition according to Claim 1 which comprises the resin and formaldehyde condensate in a weight ratio of 50 - 95 : 5 - 50.
3. A composition according to Claim 2 which comprises the resin and formaldehyde condensate in a weight ratio of 65 - 85 : 15 - 35.
4. A composition according to Claim 3 which comprises the resin and formaldehyde condensate in a weight ratio of 75 : 25.
5. A composition according to Claim 1 wherein the condensate of formaldehyde and melamine is an uncured condensate.
6. A composition according to Claim 5 wherein the con-densate is trimethylol melamine.
7. A composition according to any one of Claim 2, 3, and 4 wherein the condensate of formaldehyde and melamine is an uncured condensate.
8. A composition according to Claim 1 which also comprises 0.5 to 100% by weight (based on the weight of the resin) of an inorganic dispersing agent having at least one dimension less than 100 mµ and all dimensions less than 15µ and stable to 150°C.
9. A composition according to Claim 8 wherein 0.5 to 20% by weight (based on the weight of the resin) of the inorganic dispersing agent is present.
10. A composition according to Claim 8 wherein the dispersing agent is silica of particle size 3 to 80 mµ.
11. A composition according to any one of Claims 2, 3 and 5 which also comprises 0.5 to 100% by weight (based on the weight of the resin) of silica of particle size 3 - 80 mµ.
12. A composition according to Claim 8 which comprises a particulate material of particle size 0.2 µ to 2mm and stable to 150°C.
13. A composition according to Claim 12 wherein the particulate material is selected from the group consisting of flame retardants, lubricants and metal powders.
14. A composition according to Claim 1 which comprises the resin dissolved in an organic solvent.
15. A composition according to Claim 1 wherein the resin has been prepared by reacting an aralkyl diether or dihalide of formula R1 (CH2OR)2 or R1 (CH2X)2 wherein R is an alkyl group of 1 - 5 carbon atoms, X is chlorine or bromine, with a molar excess of a phenolic compound as defined in Claim 1 or a mixture of said phenol with non-phenolic aromatic compound.
16. A composition according to Claim 15 wherein the resin is prepared by reacting the diether with the phenolic compound.
17. A composition according to Claim 16 wherein R1 is selected from the group consisting of phenylene and phenylene substituted by at least one of methyl and halogen substituents.
18. A composition according to Claim 15 wherein the aralkyldiether is p-xylylene glycol dimethyl ether.
19. A composition according to any one of Claims 5, 6, and 10 which comprises (a) a resin prepared by reacting a molar proportion of p-xylylene glycol dimethyl ether or p-xylylene dichloride with 1.4 - 2.5 molar proportions of a phenol selected from the group consisting of phenol, resorcinol, catechol and 4-methyl catechol, and (b) an uncured condensate of formaldehyde and melamine, the weight ratio of resin to condensate being in the range 65 - 85 : 15 - 35.
20. A product obtained by curing a composition as claimed in Claim 1.
21. The product of Claim 20 wherein said composition is cured in the presence of at least one fibrous laminate base to form a laminate.
22. The product of Claim 20 wherein said composition is cured in the presence of at least one molding additive selected from the group consisting of inorganic fillers, pigments, accelerators and antistaining agents to form a molded product.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
23. A resin composition which comprises (a) a resin having repeating units of the formula wherein R' is a divalent or trivalent aromatic hydrocarbyl or divalent or trivalent di (aromatic hydrocarbyl) - oxy group or derivative thereof, substituted by at least one of an alkyl group of 1 to 6 carbon atoms, a halogen atom and a phenyl group, and Ar is a residue formed by removal of two nuclear hydrogen atoms from a phenolic compound having 1 - 3 hydroxyl groups and at least two nuclear hydrogen atoms, and n is 0 or 1, and (b) an uncured or partly cured condensate of formaldehyde or a compound forming formaldehyde in situ and melamine, said condensate containing at least two hydroxy-methyl groups per molecule attached to nitrogen atoms and providing 55-90% by weight of the total weight of resin and condensate.
24. A composition according to Claim 23 which contains 58 - 74% by weight of condensate.
25. A composition according to Claim 23 which contains 74 - 90% by weight of condensate.
26. A composition according to Claim 23 wherein the condensate contains an average of at least 2.5 hydroxy methyl groups per molecule attached to nitrogen atoms.
27. A composition according to Claim 23 wherein the condensate contains only one structural unit derived from melamine.
28. A compound according to Claim 23 wherein the condensate is trimethylol melamine or hexamethylol melamine.
29. A composition according to Claim 23 wherein the resin has been prepared by reacting an aralkyl ether or halide of formula R' (CH2OR)a or R'(CH2X)a wherein R is an alkyl group of 1 - 5 carbon atoms, X is chlorine or bromine, and a is 2 or 3, with a phenolic compound as defined in Claim 23 in a molar amount of 1.3 - 3.0 moles per mole of aralkyl ether or halide.
30. A composition according to Claim 29 wherein the resin is prepared by reacting the diether with the phenolic compound.
31. A composition according to Claim 29 wherein R is mononuclear.
32. A composition according to Claim 31 wherein the aralkyl diether is p-xylylene glycol dimethyl ether.
33. A composition according to any one of Claims 28, 30 or 32, which comprises (a) the resin made by reacting aralkyl ether or halide of formula R'(CH2OR)2 or R'(CH2X)2 where R is a mononuclear aromatic group and R is an alkyl group of 1 to 6 carbon atoms with a phenol, which is selected from the group consisting of phenol, resorcinol, catechol and 4-methylcatechol;
in a molar amount of 1.3 - 2.0 moles per mole of aralkyl ether or halide, and (b) 60 - 70% by weight uncured melamine formaldehyde condensate with only one structural unit derived from melamine and containing an average of at least 2.5 hydroxy-methyl groups per molecule.
in a molar amount of 1.3 - 2.0 moles per mole of aralkyl ether or halide, and (b) 60 - 70% by weight uncured melamine formaldehyde condensate with only one structural unit derived from melamine and containing an average of at least 2.5 hydroxy-methyl groups per molecule.
34. A composition according to any one of Claims 28, 30 or 32, which comprises (a) the resin made by reacting aralkyl ether or halide of formula R'(CH2OR)2 or R'(CH2X)2 where R
is a monouclear aromatic group and R is an alkyl group of 1 to 6 carbon atoms with a phenol, which is selected from the group consisting of phenol, resorcinol, catechol and 4-methyl-catechol, in a molar amount of 1.3 - 2.0 moles per mole of aralkyl ether or halide, and (b) 80 - 90% by weight of uncured melamine formaldehyde condensate with only one structural unit derived from melamine and containing an average of at least 2.5 hydroxymethyl groups per molecule.
is a monouclear aromatic group and R is an alkyl group of 1 to 6 carbon atoms with a phenol, which is selected from the group consisting of phenol, resorcinol, catechol and 4-methyl-catechol, in a molar amount of 1.3 - 2.0 moles per mole of aralkyl ether or halide, and (b) 80 - 90% by weight of uncured melamine formaldehyde condensate with only one structural unit derived from melamine and containing an average of at least 2.5 hydroxymethyl groups per molecule.
35. A product obtained by curing a composition according to Claim 23.
36. The product of claim 35 wherein said composition is cured in the presence of at least one fibrous laminate base to form a laminate.
37. The product of claim 35 wherein said composition is cured in the presence of at least one molding additive selected from the group consisting of inorganic fillers, pigments, accelerators and antistaining agents to form a molded product.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1524075A GB1476417A (en) | 1975-08-01 | 1975-08-01 | Process for the construction of a building |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1048676A true CA1048676A (en) | 1979-02-13 |
Family
ID=10055552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA74190153A Expired CA1048676A (en) | 1975-08-01 | 1974-01-15 | Resin composition comprising aralkylene phenol resin and formaldehyde condensate |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1048676A (en) |
| GB (1) | GB1476417A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11913242B2 (en) | 2021-04-16 | 2024-02-27 | Big Time Investment, Llc | Building assembly system and associated method |
-
1974
- 1974-01-15 CA CA74190153A patent/CA1048676A/en not_active Expired
-
1975
- 1975-08-01 GB GB1524075A patent/GB1476417A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1476417A (en) | 1977-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4972031A (en) | Plastic moulding composition comprising an uncured or partly cured thermoset resin precursor and a polyarylsulphone | |
| US5376453A (en) | Epoxy resin compounds in admixture with glycidyl phosphorus compounds and heterocyclic polyamines | |
| EP0311349B1 (en) | Polymer composition | |
| KR101457449B1 (en) | Thermosetting composition | |
| US6605354B1 (en) | High nitrogen containing triazine-phenol-aldehyde condensate | |
| US4318821A (en) | Polymeric compositions | |
| SG194558A1 (en) | Trimethyl borate in epoxy resins | |
| KR20010031139A (en) | Conductive thermoset molding composition and method for producing same | |
| US4946928A (en) | Curable resin from cyanate aromatic ester and propargyl aromatic ether | |
| CA1048676A (en) | Resin composition comprising aralkylene phenol resin and formaldehyde condensate | |
| JPS6118937B2 (en) | ||
| US3923721A (en) | Resin compositions | |
| US4108822A (en) | Curable resin compositions | |
| US3632555A (en) | Preparation of epoxylated phenolic resins by reacting polymers fro aralkyl ethers and phenols with epihalohydrin | |
| US4020035A (en) | Resin compositions | |
| US4916203A (en) | Curable resin composition from epoxy compound and propargyl aromatic ether | |
| US3729433A (en) | Method of preparing polyarylene polymers with alkyl amino aromatics,compositions thereof and products | |
| US5096987A (en) | Dipropargyl ether or alpha, alpha'-bis(4-hydroxyphenyl)-para-diisopropylbenzene | |
| US5965671A (en) | Modified phenolic resin toughened by poly (alkylene oxide) and preparation thereof | |
| JPS61235413A (en) | Production of phenol-modified aromatic hydrocarbon/ formaldehyde resin | |
| EP0410547B1 (en) | Propargyl aromatic ether polymers | |
| US5204415A (en) | Polymers prepared from dipropargyl ether of alpha, alpha'-bis (4-hydroxyphenyl)-para-diisopropylbenzene | |
| US4987272A (en) | Dipropargyl ether of alpha, alpha'-bis (4-hydroxypenyl)-paradiisopropylbenzene | |
| US3338844A (en) | Process for making arylene-containing polymers | |
| US3915934A (en) | Curing of phenolic resin systems with zinc borate |