CA1053440A - Method of bonding with an anaerobically cured adhesive - Google Patents

Abstract

Abstract of the Disclosure Solid particulate material are bonded together to form a shaped article by (i) forming a mixture of the particles and an anaerobically-curing adhesive and moulding the mixture to the desired shape, (ii) initiating cure of the adhesive to bond the particles together by maintaining the shaped article in a substantially oxygen-free environment, and (iii) heating the shaped article to complete the cure of the adhesive.
The anaerobic adhesive may comprise, as monomer, an ester of an acrylic acid, with a hydroperoxide or peroxide a a polymerisation catalyst, and the oxygen-free environment may be produced by displacing air with nitrogen or other inert gas or vapor. Heating to accelerate the cure may be effected by using hot nitrogen, or the shaped article may be heated by dielectric heating, for example.
The method described is suitable for the production of foundry moulds and cores, which rapidly attain high compression strengths, form sand or other particulate material.

Description

iO53~40 THIS INVENTION relates to a method of bonding together solid particulate materials to form shaped srticles. The methot is especially applicable to the binding of refractory particulate material for making foundry cores and moulds and the invention will be described with especial reference to making such cores and moulds.
~owever, the method is also useful in making other kinds of shaped articles from particulate materials, including exothermically-reacting compositions, for example.
In the production of foundry moulds and cores, sand or other refractory particulate material is bonded together by means such as the deposition of a silica hydrogel, achieved by coating the particles with aqueous sodium silicste and moulding them to the desired shape, then treating with carbon dioside or other acid gas and sllowing the m4xture to harden in its ulded shape. Other methods which have been used involve coating the particles with a curable synthetic resin composition, such as a urea-formaldehyde resin composition, and curing the composition.
A disadvantage of methods hitherto available is that the development of a cohesive strength sufficient for the cores to be hsndled under foundry conditions usually takes several hours, sometimes twelve or re: currently, the foundry industry seeks, for re economical working, methods which will provide cores attaining adequate cohesive strength within, at st, one hour yet which employ only low proportions of bonding agent.
~5 Wo have now found that these requirements can be at least -- .

i0534~0 substantially met by the use of anaerobically-curing adhesives.
These adhesives, which usually contain acrylate ester monomers, ~re stable on storage in air or other oxygen-containing gas but, in the presence of a catalyst, they polymerise when the oxygen is excluded.
The reason usually advanced for this behaviour is that radicals continuously genersted in the adhesive composition react with the oxygen while this is available: when, however, oxygen is excluded, the rsdicals induce polymerisation of the monomer.
We have further found that, by the application of heat, high cohesive strengths can be rapidly obtained without the need for maintaining for prolonged periods the shaped ob~ect in a substantially oxygen-free environment.
This invention accordingly provides a method of making a shaped article from particulate solid materiai which comprises (i) forming a mixture of the particles and an anaerobically-curing a & esive and moulding the mixture to the desired shape, (ii) initiating cure of the adhesive to bond the particles together by maintaining the shaped article in a-substantially oxygen-free environment, and tiii) heating the shaped article to complete the cure of the adheiive.
Preferably the substantially oxygen-free environment is attained by displacing air or other oxygen-containing gas by a gas or vapor which does not inhibit curing of the anaerobic adhesive, nitrogen -being particularly suitable, but it may also be attained by pumping i053~0 out the air. Preferably, too, the shaped object is maintai~ed in a substantially oxygen-free environment for a minimum of 10 minutes so that curing has advanced substantially before air can seep back into the interstices of the shaped object and so inhibit further curing. Ingress of air while the a& esive is curing can also be prevented by wrapping the shaped article in an air-impermeable film or by coating it with an air-impermeable film sealing composition formed in situ by coating the surface with an aerobically-curing agent for the adhesive.

The shaped article is preferably heated for from half a minute to ten minutes, especially from one to three minutes, and at a temperature in the range 40C to 350C, especially from 50 to 150C.
It may be heated by direct heat, by using a hot inert gas or vapor ( by inert gas or v~por " is meant one which does not inhibit curing of the anaerobic adhesive), especially nitrogen, to displace the air or other oxygen-containing gas, or by dielectric heating, i.e., radio-frequency heating.
The preferred anaerobic adhesives comprise (a) an ester of an acrylic acid, (b) a hydroperoxide or peroxide as polymerisation catalyst for ~a), and, if desired, (c) an accelerator for the polymerisation of (a).
Suitable esters of acrylic acids include those of the general formula C~2 ~ o ~ 2)o~ )c CliO ¦ ~I s Cfi2 where a i~ an integer of 1 to 8, b is an inte8er of 1 to 20, c is zero or l, O
R denote~ -H, -C~3, C2~sc CH2 ~ 2 1 2 R
Rl denotes -H, -Cl, -CH3, or -C2R5, and R denotes -~, -0~, or -OCC-C~2.

R
Preferred among such co~pound- &re those of formula I where a is 1, b is from 2 to 5, c is ~4ro, a~ d Rl ea~h denote -~ or -CH3. Compounds of formula I are described in United Kingtom Patent Specification No. 824677.
Other suitable esters are of the general formula CH2 I C ~ ( Z)d ~1~ c ~ e ll where b, c, Rl, and R2 have the meanin8s assigned above, d is zero or positive integer, provided that c and d are not both zero, ' e iA 1, 2, 3, or 4, and R3 denotes an organic radical of valency e linked through' a carbon atom or carbon atom~ thereof'tb'the indicated b oxygen atoms.
Preferred among such compound~ are those where, in formula II7 b, c, and d are each 1, Rl i8 -H or'-Ca3, and R3 i8 the hydrocarbon `` iO53440 re~idue of an aliphatic alcohol containing from 1 to 6 carbon atoms, such as -C~3 or CH2 ~ C CH2 ~ C~2 .
Compound6 of for~ula II are de~cribed in Unitet Xingdom Patent Specification No. 1228479.
~et other suitable esters are those of the formula CH2 - C - - O - C~2-CH-CH2-0 () ~ R5 III

where c and e have the mesnings previously assigned, R4 denotes -~ or -C~3, and R5 denotes an orga~ic radical of valency e, lin~ed through a carbon atom thereof other than the csrbon atom of 8 carbonyl group.
More particularly, ~h~c c i8 sèro, R5.may-dencte-~he residue, contiining from 1 to 18 csrbon atoms, of ~n lcohol or phenol having e hydroxyl groups.
R5 ma~ thus represent an aromatic, sraliph~tic, alkaromatic, cycloaliphatic, heterocyclic, or heterocycloaliphatic group, such as an aro~atic group containing only one benzene ring, optionally substituted by chlorine or by alkvl groups each of from 1 to 9 carbon atoms, or an aromatic .group co~prising a chain of two to four ben~ene ring~, optionally ~
interrupted by ether o y gen atoms, aliphatic hydrocarbon groups of 1 to 4 carbon atoms, or sulfon~ groups, esch benzene ring being optionally subs~ituted by chlorine or by ~lkyl groups each of from 1 to 9 car~on atoms, - ~OS3~0 or, preferably, a saturated or unsaturated, strsight or branched-chain aliphatic group, which may contain ether oxygen lînkages and which may be substituted by hydrosyl groups, e~pecially a saturated or ~onoethylenically-unsatura~ed stralght chain aiiphatic hydrocsrbon group of from 1 to 8 carbon aeoms, Specific examples of such groups are the aromatic groups of the formulae -C6H5 and -C6H4CH3, in which case e i8 1, -C6H4C(CH3)2 C6H4-, ant -C6H4CH2C6H4-, in which case e is 2, and -C6H4(G~2~6H33fCN2C6H4-where f is 1 or 2, in which case e is 3 or 4, and the aliphatic groups

2~CH2 Dr C~2 ~ (CH2)3CH2-, in which case e is 3 , 2 4 2 2 ~ CH2CH20CH2CH2-, or -(CH2CH 0) CH CH -in which case e i6 2 , or of the formula -(GH2)3CH3, -(CH2)40H, 2 2 2ÇH CHCH20~, in which case e is 1.
When c is 1, R5 may represent the residue, containing from l to 60 carbon atoms, of an acit.having e carboxYl groups, preferably a saturated or ethylenicelly-unsaturated, strai8ht chain or branched aliphatic hydrocarbon group of from 1 to 20 carbon atoms, which may be substituted by chlorine atoms and which may be interrupted by ether oxygen atoms andlor by carbonyloxy groups, or a saturated or ethylenically-unsaturated cycloaliphatic or aliphatic-cycloaliphatic hydrocarbon group of at least 4 carbon atoms, which may be substituted by chlorine atoms, or an aromatic hydrocarbon group of from 6 to 12 carbon atoms, which may be substituted by chlorine atom~.
Further preferred are such co~pounds in which R5 represents a saturated or ethylenically-unsaturated straight chain or branched aliphatic hydrocarbon group of from 1 to 8 carbon atoms, optionally substitut2t by a hydro~yl group, or ` 10534~0 a 6aturated or ethylenically-unsaturated straight chain or branched aliphatic hydrocarbon group of from 4 to 50 carbon atoms and interrupted in the chain by carbonyloxy groups, or a saturated or ethylenically-unsaturated nocyclic or dicyclic cycloaliphstic hydrocarbon group of 6 to ~ carbon atoms, or an ethylenically-unsaturated cycloaliphatic-aliphatic hydrocarbon group of from 10 to 51 carbon atoms, or a mononuclear aromatic hydrocarbon group of from 6 to 8 carbon atoms.
Specific examples of these residues of ca~boxylic acids are

3, 2C~3, CH2C~(OH)CH3, -C~2Cl and -C6H5, in which case e i8 1 and -C~2C~2-, -CH-CH-, and -C6H4-, in which case e is 2.
Compounts of the general formula III are described in United Kingdom Patent Specifications Nos. 831056, 977361, 989201, 1006587, 1054614, 1146474,1195485, 1222369, 1235769, 1241851, 1262692, and 1266159, Canadian Pstet Specifications Nos. 8046io and 888274, United States Patet Specification No. 3221043, and French Pa*ent Specification No~ 1531224.
Still other suitable esters are acrylate-ureth~nes and acrylate-ureides of the general formula [ C~2 ~ C - C - 0 _ R6 _ X - ~ _ N~ ~ R7 IV

g where iOS3~40 Rl has the meaning assigned above, R6 denotes a divalent aliphatic, cycloaliphatic, aromatic, or araliphatic group, bound through a carbon atom or carbon atoms thereof to the indicated -0- atom and -X- atom or group, X denotes -0- or -N(R8)-, where R8 stands for -H or an alkyl radical of from l to 8 carbon atoms, is an integer of at least 2 and at most 6, and R7 denotes a ~valent cycloaliphatic, aromatic, or araliphatic group bouna through a carbon a~om;or carbon atoms thereof to the indicated NH groups.
Preferably R6 denotes a divalent aliphatic group of 2 to 6 carbon atoms and R7 denotes one of the following:
a divalent aliphatic group of 2 to 10 carbon atoms, such as a group of formula -(CH2)6-~ -CH2c(cH3)2cH2cH(c~3)(cH2)2-' or -CH2CH(CH3)CH2c(cH3)2(cH2)2 ;
a phenylene group, optionally substituted by a methyl group or a chlorine atom;
a naphthalene group;
6 4 6 4 C6H4CH2C6H4-- or -C6H4C(CH3)2C H -; or 20 a mononuclear alkylcycloalkylene or alkylcycloaikylalkylene group of from 6 to lO carbon atoms, such as methylcyclohex-2,4-ylene, methylcyclohex-2,6-ylene, or 1,3,3-trimethylcyclohex-5-ylenemethyl group.
Compounds of the general formula IV are described in United ~ingdom Paten~ Specification No. 1132821.
Yet other s~itable acrylates are those of the general formula lOS3440 O OH
. 1 8 ~H2 C C - O - ~2CHCH2 - N - R
l [ R9]. . V
OH I J
2 I C O - CH2CHCH2 ~ N-R8 ]

R
where each R has the meaning previously assigned~
esch R denotes -H or an alkyl radical of 1 to 6 carbon atoms, 5 optionally substituted by a cyano or hydroxyl group or by a group q ,OH
of formula CH2 - Cl - ~ - O CH2CHCH2 , Rl ; each R is 8 divalent aliphatic,aromatic, heterocyclic or cycloaliphatic re6idue of 1 to 10 carbon atoms, linking through carbon atoms thereof the indicated nitrogen atoms, h is zero or an integer of from 1 to 3, and i i8 zero or h.
R8 preferaU y denotes. an iso~ropyl group.
R preferably denotes an ethylene, propylene, or r phenylene group.
15 A specific example of a compound of the general formula Y is that of the formula r C i~ 1 L 2 2 2 ~ 3 2 VI
-Compounds of the general formula V are described in United Kingdom Patent Specification No. 1339017.

`` lOS~ 0 `
Organic hydroperoxides which may be used as polymerisation cat:alysts include those of formula Rl OOH, where R10 is a monovalent organic radical containing up to 18 carbon atoms, especially an alkyl, aryl, or aralkyl radical containing ~rom 4 to 13 carbon atoms. Typical hydroperoxides are ethyl methyl ketone hydroperoxide, tert.butyl hytroperoxide, cumene hydroperoxide, and hydroperoxides formed by the oxygenation of cetene or cyclohexene, tert.butyl hydroperoxide and cumene hydroperoxide being especially effective. Hydrogen peroxide may also be employed. A range of organic peroxides may be used, such as 2,5-dimethyl-2,5-di(tert.butylperoxy) hexane, di-tert.butyl peroxide, dihexylene glycol peroxide, t .butyl cu~yl peroxide, isobutyl methyl ketone peroxide, and also peresters such as tert.butyl peracetste, tert.butyl perbenzoate, and tert.butyl perphthalate.
Suitable accelerators (c) include polyalkylenepolyamines, specific examples being diethylenetriamine and triethylenetetramine;
polyisocyanates, such as toluene-2,4-di-isocyanate; aldimines;
tertiary amines, such as N,N-dimethylbenzylamine and triethylamine;
imides and sulfimides. such as o-benzoic sulfimide; dithiocarbamates;
20 amides and thioamides such as formamide; thiazoles such as 2-mercaptobenzthiazole; ascorbic acid; organic phosphites; quaternary ammonium salts and bases; salts of transition metals; thioureas;
and polymercaptans, especially esters of mercaptancarboxylic acids, such as glycerol tris(thioglycollate). Poly~ercaptans and 25 polyalkylenepolyamines are particularly preferred, and the accelerating effect of polyalkylenepolyamines can often be enhanced by including ~0534~(1 a stoichiometric deficit ( calculated on the amino-hydrogen content) of a monocarboxylic acid, alkanoic and alkenoic acids such as n-heptanoic acid and acrylic acid being particularly suitable.
The a unt of hydroperoxide or peroxide (b) may vary between 0.01% and 15% by weight of the ester (a); quantities of from 1%
to 10% by weight are, however, generally used. The amount of accelerator (c) used is also preferably from 1 to 10~ by weight of the ester (a).
The anaerobic adhesive may also contain various additives, such as inhibitors to prevent premature polymerisation, diluents, and thickeners. Typical inhibitors are qu;nones or hydroqulnones:
they may be employed in quantities of 0.001 to 0.1% by weight of the ester (a). It is generally desirable that the anaerobic adhesive is a liquid of low viscosity and it may be useful to add a diluent to lower the viscosity.
Anaerobic adhesives. are, in the absence of the accelerator (c), stable for prolonged periods in the presence of a sufficient quantity of oxygen but cure when oxygen is excluded. They are therefore best stored in containers which have an adequate air space 'therein and/or are permeable to air.
The proportion of anaerobic adhesive to particulate material is usually'fro~ 0.5 to 10%,'and especially 1 to 5%, by weight; larger a u~ts may be used but may prove uneconomic: the proportions are, of course, chosen so that the shaped article is permeable, for displacement of the oxygen-containing gas.
The anaerobic adhesive may be mixed with the particulate material _ 1~ --` 105;~49tO
by any known method. If desired, where the anaerob;c adhesive co~nprises two interacting substances, such as components (a) ant (b) above, the particulate material may be divided into two portions, the first of which is coated with component (a) and the second with component (b). The accelerator (c), if used, may be mixed with either portion. Coating may be carried out by, for example, using a laboratory mixer, by tumbling in a rotating drum, by spraying, or by dipping. The coated portions are stored separately until required, at which time they are brought into intimate contact and curing is caused to proceed. When the particulate material is a oundry refractory material it is particularly con~enient to use an apparatus for mixing and discharging the sand directly into core boxes, such as that described in United Kingdom Specification No, 1133255.
The following ~xamples illustrate the invention: temperatures are in degrees Celsius.
The acrylates and methacrylates employed were made as described below. Epoxide contents were measured by titrating against a 0.1 ~
solution of perchloric acid in acetic acid in the presence of excess of tetraethylammonium bromide , crystal violet being used as the indicator.
Product A
This is substantially 1,4-bis(2-hydroxy-3-methacryloyloxypropoxy)butane, which was prepared by adding, to a stirred mixture of methacrylic acid ( 67 g), triethylamine ( 1 g), and hydroquinone (0.1 g) heated at 120 in a flask fitted with a reflux condenser, 100 g of butane-1,4-diol diglycidyl ether ( epoxfde content 7.8 equiv./kg) over ~ hour and stirring the mixture at 120 for 1 hour longer, by which time its epoxide content was zero.

` iO53440 ~roduct B
This is substantially 1-(2-hydroxy-3-methacryloyloxypropoxy)hutane~
which wa~ prepared in a similar manner from 60.6 g of methacrylic acid and 100 g of n-butyl glycityl ether ( epoxide content 7.05 equiv.lkg) in the presence of 2 g of triethylamine and 0.1 g of hydroquinone.
Product C
A mixture of adipic acid ( 30 g), glycidyl methacrylate ( SB.2 g), triethylanune ( 1 g), and hydroquinone ~ 0.1 g) wa6 heated at 120 for 2~ hours with stirring in flask fitted with a reflux condenser.
At this time the epoxide content of the product was zero.
Product C is substantially bis(2-hydroxy-3~methacryloyloxypropyl) adipate.
Product D
This i6 substantially 2-hytro~y-3~methacryloyloxypropyl propionate (glycerol methacrylate propionate), which was prepared by heating at 120 a stirred mixture of glycidyl methacryla~e ( S0 g), propionic acid (26 g), triethylamine (0.7 g), and hydroquinone (0.07 g) for 2.5 hours, by which time the epoxide con~ent of the mixture was zero.

Product E
2~
iq tetraethylene glycol diacrylate.
Product F
is tetraethylene glycol bis(methacrylate).
Product G

:25 To a mixture of methacrylic acit ( 61 g), hytroquinone (0.2 g), and triethylamine ~ 2 g), stirred at 120, was atded over 1 hour a mixture of 8D g of butsne-1,4-tiol diglycidyl ether ( epoxite contenc - 14 ~

iO53440 7.7 equiv./kg) and 20 g of an epoxy novolak resin ( having an epoxide content of 5.48 equiv./kg and being a polyglycidyl ether of a phenol-formaldehyde novolak which had a number average molecular weight of 420). The mixture was stirred at 120 for 1 hour further, at which time the epoxide content was zero.
Product G is a mixture of 1,4-bis(2-hydroxy-3- methacrylo~loxy)butane and a poly(~-methacryloyloxy-2-hydroxypropyl) ether of a phenol-formaldehyde novolak, having the formula ~ 3 ~ CH
CH2oCCOOCH2CHCH2f OCH2 CH200CC CH2 ~ 2 ~ ) Z

CH2'eOOCCH2CHCH20 OH

where m is an integer of average value 2.07.

Product H

To 87 g of toluene di-isocyanate ( a mixture of the 2,4- and 2,6-isom~rs) was added with stirring 65 g of 2-hytroxyethyl methacrylate.

An exothermic reaction set in and the temperature was allowed to rise lS to 90 within 10 minutes. Then a further 66 g of 2-hytroxyethyl methacrylate was added over 30 minutes without any heating. Hydroquinone (0.2 g) was added and the mixture was then stirred at 100 for 1 hour.

Product H is a mixture of 2,4- and 2,6-bis(2-methacryloyloxyethoxy-carbonamido)toluene, substa~tially of the formula - 15 ~

`iO5349t0 - CH2 ~ CCOOCH2CH200CNH ICH3 I ~
3 ~
NHCOOCH2CH200Cf = CH2 Product I CH
is l,l,l-trimethylolpropane tris(methacrylate).
Product J
To a stirred mixture of Product A (166 g) and toluene (300g ) at 65 was added methacryloyl chloride ( 16 g, i.e. 0.2 equiv., calculated on the hydroxyl content of Product A) dropwise over 30 minutes. The mixture was then stirred at 80 for 2 hours, and the solvent was removed under reduced pressure. Product J comprises a mixture of 1,4-bis(2-hydroxy-3-methacryloyloxypropoxy~butane, 1-(2,3-bis(methacryloyloxy)propoxy)-4-(2-hydroxy-3-methacryloyloxypropoxy) butane,and 1,4-bis(2,3-bis(methacryloyloxy)propoxy)butane.

lOS3~9~0 The following compositions were prepared, the figures denoting parts by weight I 90 Product A
cumene hydroperoxide triethylenetetramine 4900 sand (2% adhesive on weight on sand~
II 90 Product A
cumene hydroperoxide triethylenetetramine 2.5 methacrylic acid 5022 sand (2% adhes;ve on weight of sand) III 90 Product A
cumene hydroperoxide . glycerol trithioglycollate 2.5 methacrylic acid 5022 sand (2% adhesive on weight of sand) IV 90 Product B
- 5 cumene hydroperoxide triethylenetetramine 2.5 methacrylic acid 5022 sand (2% adhesive on weight of sand) V 90 Product C
S cumene hydroperoxide triethylenetetramine 4900 sand (2% a &esive on weight of sand) VI 90 Product D
cumene hydroperoxide S triethylenetetramine 4900 sand (2% adhesive on weight of sand~
VII90 Product E
cumene hydroperoxide triethylenetetramine 4900 sand .(2% adhesive on weight of sand) VIII 90 Pr~duct F
cumene hydroperoxide triethylenetetramine 4900 sand (2% a & esive on weight of sand) .IX90 . Product G
cumene hydroperoxide triethylenetetramine 8233 . sand 25: (1.2% adhesive on weight of sand) ` 105~440 X 90 Product G
cumene hydroperoxide triethylenetetramine 4066 sand (2.4X adhesive on weight of sand) The sand used, Chelford W & S sand, is a washed and screenedfoundry sand from Chelford, Cheshire~England~ ha~ng the following typical sieve analysis:-British Sts`ndard Sieve No.
16 trace 22 0.8

4.2 44 20.4 100 26.0 150 2.8 200 0.3 ~ ~ 200 trace - The sand was mixed with the other components of the Compositions except the triethylenetetramine or glycerol trithioglycollate; the latter was then added and mixed vigorously for a few seconds. Similar results could be obtained by first mixing the sand with the triethylenetetramine or glycerol trithioglycollate and then adding - the other components. The Composition~ were used within a few minutes of mixing to produce a standard AFS (American Foundrymell's Society) compression test piece 5 cm x 5 cm. When making the compression pieces 105~4(~ `
using Composition~ IV the mixtures were used within one minute of preparation.
Cure was initiated by blowing nitrogen ( at 18 kN/m2) through the core for the time indicated. The test pieces were heated after removal from the core box by means of a Radyne radiofrequency heater ( Model H5D/H of Radio Heaters Limited, Wokingham, Berkshire, England): the heater operated at a frequency of 36 MHz and the power was 0.2 kW, the air gap between the upper electrode and the test piece was 0.5 cm. After heating for 2, 3, and 4 minutes, the temperatures at the centres of the cores were, approximately, 80, 95, and 110. All cores were allowed to cool to room temperature ( which took about 30 to 60 minutes) before the compression strengths were measured. The results are shown in Table I.
TABLF I
_ Compositiontime in RF heating Compression strength kN/m core box (mins) before RFafter RF
(secs) heating heating . .

Il 10 2 281 2519 ~II 120 3 _ 483 ~V 120 2 _ 276 ~ 60 1 2 219 1145 VI 120 2 _ 393 VII 120 2 :97 600 Vl~l 60 4 237 345 denotes not measured _ 20 _ ` lOS~440 The procedure of Exsmple 1 was repeated, using Compositions I snd IIJ except that1instead of the test pieces being heated by means of a radiofrequency heater, the nitrogen was preheated by passage through a heated coiled iron tube before being blown through the core. The results obtained are shown in Table II.
TABLE II

Composition % adhesive Temperature Passage of Compression on sand of nitrogen nitrogen strength .
~-AC~ ~

I 2.0 20 660 384 II 2.0 20 33 16259 1 150 j None of the cores was stored in nitrogen after the nitrogen had been passed into the core box for the time indicated. Compression strengths were determined after the cores had cooled to room temperature.

Next, the following Compositions were prepared, each containing 2 of adhesive calculated on the weight of sand:-iOS349~0 XI 45 Product F
Product H
cumene hydroperoxide . 5 triethylenetetramine 5022 sand XII 90 Product I
cumene hydroperoxide 2.5 methacrylic acid triethylenetetramine 5125 sand :XIII 75 Product A
Product I
cumene hydroperoxide 2.5 methacrylic acid triethylenetetramine . 5125 sand XIV 90 Product J
cumene hydroperoxide 20 . 5 triethylenetetramine 2.5 methacrylic acid - 5125 sand XV 22.5 Product H
. 67.5 Product A
cumene hydroperoxide . 5 triethylenetetramine 5022 sand ~ 22 --Carbon dioxide, preheatet to 8ppr~xi~ately 15~ by ~as~a~e through a heated coiled iron tube and at a pres3ure of approximately 36 kN/m2, was passed into cores pr2par2d fTom Coupositi.ons I and XI to XIV for various periods. The results obtaiRed are æhown in Table III.

T~3I.~ III

CompositionPa~sage of carbonCompreææion strength dioxid~, into core (kN/m2) box (se_s.) , .I 30 320 . 60 1562 . 90 2200 . 120 8624 XII 120 . 1650 . XTII 30 792 . 60 2530 . 30 770 . 60 . 2640 . 120 8404 . . _ _ .

- 23 ~

Claims (26)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of making a shaped article from particulate solid material which comprises (i) forming a mixture of the particles and an anaerobically-curing adhesive and moulding the mixture to the desired shape, (ii) initiating cure of the adhesive to bond the particles together by maintaining the shaped article in a substantially oxygen-free environment, and (iii) heating the shaped article to complete the cure of the adhesive.

2. Method according to claim 1, in which the substantially oxygen-free environment is attained by displacing air or other oxygen-containing gas by a gas or vapor which does not inhibit curing of the anaerobic adhesive.

3. Method according to claim 2, in which the air or other oxygen-containing gas is displace by nitrogen,

4. Method according to any of claims 1 to 3, in which the shaped article is maintained in a substantially oxygen-free environment for a minimum of 10 minutes.

5. Method according to claim 1, in which ingress of air into the shaped article while the adhesive is curing is prevented by wrapping the shaped article in an air-impermeable film.

6. Method according to claim 1, in which ingress of air into the shaped article while the adhesive is curing is prevented by coating the shaped article with an air-impermeable sealing composition formed in situ by coating the surface of the shaped article with an aerobically-curing agent for the adhesive.

7. Method according to claim 1, in which the shaped article is heated for from half a minute to ten minutes.

8. Method according to claim 1, in which the shaped article is heated at a temperature in the range 40° to 350°.

9. Method according to claim 1, in which the shaped article is heated by means of a hot inert gas or vapor.

10. Method according to claim 1, in which the article is heated by dielectric heating.

11. Method according to claim 1, in which the anaerobic adhesive comprises (a) an ester of an acrylic acid of the general formula where a is an integer of 1 to 8, b is an integer of 1 to 20, c is zero or 1, R denotes -H, -CH3, -C2H5, -CH2OH or R2 denotes -H, -OH, or , and R1 denotes -H, -C1, -CH3, or -C2H5, and (b) a hydroperoxide or peroxide as polymerization catalyst for (a).

12. Method according to claim 1, in which the anaerobic adhesive comprises (a) an ester of an acrylic acid of the general formula where b, c, R, and R1 have the meanings assigned in claim 11, d is zero or a positive integer, provided that c and d are not both zero, e is 1, 2, 3, or 4, and R3 denotes an organic radical of valency e, linked through a carbon atom or carbon atoms thereof to the indicated b oxygen atoms, and (b) a hydroperoxide or peroxide as polymerization catalyst for (a).

13. Method according to claim 12, in which R3 is the hydrocarbon residue of an aliphatic alcohol containing from 1 to 6 carbon atoms.

14. Method according to claim 1, in which the anaerobic adhesive comprises (a) an ester of an acrylic acid of the general formula where c has the meaning assigned in claim 12, e has the meaning assigned in claim 13, R4 denotes -H or -CH3, and R5 denotes an organic radical of valency e, linked through a carbon atom other than the carbon atom of a carbonyl group, and (b) a hydroperoxide or peroxide as polymerization catalyst for (a).

15. Method according to claim 14 in which c is zero and R5 denotes the residue, containing from 1 to 18 carbon atoms, of an alcohol or phenol having e hydroxyl groups.

16. Method according to claim 14 in which c is 1 and R5 denotes the residue, containing from 1 to 60 carbon atoms, of an acid having e carboxyl groups.

17. Method according to claim 1, in which the anaerobic adhesive comprises (a) an ester of an acrylic acid of the general formula where R1 has the meaning assigned in claim 12, R6 denotes a divalent aliphatic, cycloaliphatic, aromatic, or araliphatic group, bound through a carbon atom or carbon atoms thereof to the indicated -O- atom and -X- atom or group, X denotes -O- or -N(R8), where R8 stands for -H or an alkyl radical of from 1 to 8 carbon atoms, g is an integer of at least 2 and at most 6, and R7 denotes a g-valent aliphatic, cycloaliphatic, aromatic, or araliphatic group, bound through a carbon atom or carbon atoms thereof to the indicated NH groups, and (b) a hydroperoxide or peroxide as polymerization catalyst for (a).

18. Method according to claim 17, in which R6 denotes a divalent aliphatic group of 2 to 6 carbon atoms.

19. Method according to claim 17, in which R denotes a divalent aliphatic group of 2 to 10 carbon atoms; a phenylene group, optionally substituted by a methyl group or a chlorine atom; a naphthalene group; a group of formula -C6H4C6H4-, -C6H4CH2C6H4-, or -C6H4C(CH3)2C6H4-; or a mononuclear alkylcycloalkylene or aIkylcycloaIkylalkylene group of 6 to 10 carbon atoms.

20. Method according to claim 1, in which the anaerobic adhesive comprises (a) an ester of an acrylic acid of the general formula where each R1 has the meaning assigned in claim 11, each R8 denotes -H or an alkyl radical of 1 to 6 carbon atoms, optionally substituted by a cyano or hydroxyl group or by a group of formula each R9 is a divalent aliphatic, aromatic, heterocy¢lic, or cyclo-aliphatic residue of 1 to 10 carbon atoms, linking through carbon atoms thereof the indicated nitrogen atoms, h is zero or an integer of from 1 to 3, and j is zero or h, and (b) a hydroperoxide or peroxide as polymerization catalyst for (a).

21. Method according to claim 11, in which the ester (a) is 1,4-bis-(2-hydroxy-3-methacryloyloxypropoxy)butane, 1-(2-hydroxy-3-methacryloyloxy-propoxy)butane, bis(2-hydroxy-3-methacryloyloxypropyl) adipate, 2-hydroxy-3-(methacryloyloxy)propyl propionate, tetraethylene glycol diacrylate, tetraethylene glycol bis(methacrylate), a poly(2-hydroxy-3-(methacryloyloxy)-propyl) ether of a phenol-formaldehyde novolak, 2,4-bis(2-methacryloyloxy-ethoxycarbonamido)toluene, 2,6-bis(2-methacryloyloxyethoxycarbonamido)-toluene, 1,1,1-trimethylolpropane tris(methacrylate), 1-(2,3-bis(methacryl-oyloxy)propoxy)-4-(2-hydroxy-3-methacryloyloxypropoxy)butane, or 1,4-bis-(2,3-bis(methacryloyloxypropoxy)) butane.

22. Method according to claim 11, in which the hydroperoxide (b) is of the formula R10OOH, where R10 denotes a monovalent organic radical con-taining up to 18 carbon atoms.

23. Method according to claim 1, in which an accelerator (c) in the anaerobic adhesive is a polyalkylenepolyamine or a polymercaptan.

24. Method according to claim 1, in which there is used from 0.5 to 10% of the anaerobic adhesive, calculated on the weight of the particulate material.

25. Method according to claim 11, in which there is used from 0.01 to 15% of the polymerization catalyst (b) calculated on the weight of the anaerobic adhesive.

26. Method according to claim 1, in which the particulate material is foundry sand.