US3892611A

US3892611A - Ingot moulds

Info

Publication number: US3892611A
Authority: US
Inventors: Peter Stanley Clark; David John Bloodworth
Original assignee: Foseco International Ltd
Current assignee: Foseco International Ltd
Priority date: 1972-03-23
Filing date: 1973-03-23
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01
Also published as: GB1398511A; CA989589A

Abstract

A plurality of elements are adhered together via a layer of heat-vulcanisable rubber of specified properties. This method may be used to fix ingot mould hot top lining slabs to the walls of an ingot mould or head box.

Description

United States Patent Clark et al. 1 July 1, 1975 1 INGOT MOULDS [75] Inventors: Peter Stanley Clark; David John References Cited Bloodworth, both of Nechells, UNTTED STATES PATENTS Brmmgham England 3,258,389 6/1966 061611166 615 211 156/338 x 73 Assignee; Foseco International Limited, 3,681,190 8/1972 Dahlquist 156/338 X Birmingham England 3,749,628 7/1973 Nancarrow et all 249/106 3,751,331 8/1973 Leverkusen 156/338 X [22] Filed: Mar. 23, 1973 211 App} N 344 0 4 Primary ExaminerEdward G. Whitby Attorney, Agent, or FirmCushman, Darby & Cushman [30] Foreign Application Priority Data Mar. 23, 1972 United Kingdom 13702/72 Apr. 20, 1972 United Kingdom 18345/72 [57] ABSTRACT A plurality of elements are adhered together via a [52] US. Cl. 156/71; 156/338; 164/137; layer of heat-vulcanisable rubber of specified proper- 249/106; 260/237 H; 260/942 R; 428/465 ties. This method may be used to fix ingot mould hot [51] Int. Cl. B22D 7/10 top lining slabs to the walls of an ingot mould or head [58] Field of Search 156/71, 338; 161/217, 221; box.

16 Claims, 1 Drawing Figure INGOT MOULDS This invention relates to a method of adhering a plurality of like or dissimilar elements; in particular this invention relates to fixing ingot mould hot top lining slabs to the walls of an ingot mould or head box.

For reasons of manufacturing simplicity. ingot mould hot top lining slabs are usually made flat and in use forced to fit the flat or more usually cambered and tapered walls of the ingot mould head or head box it is desired to line. Most types of hot top lining slabs, however, possess a degree of resilience which tends to spring the slab away from the wall of the mould or head box unless it is very firmly affixed thereto. Even fairly flexible materials are difficult to attach to the generally fairly uneven mould or head box wall.

One method of fixing hot top slabs in the desired position is by mechanically nailing or clipping the slabs in place. This method is inconvenient, time-consuming, expensive and prone to failure. Numerous previous attempts to adhere insulators to mould walls have been unsatisfactory, since no single adhesive was found which would operate satisfactorily over the wide temperature range required (room temperature to 300C) and at the same time fully support the insulator against the camber and usual unevenness of cast iron ingot mould walls.

The objection of the present invention is to overcome the above-mentioned difficulties by means of an adhesive system comprising a heat-vulvanisable rubber.

According to the present invention, there is provided a method of adhering a plurality of like or dissimilar elements, which comprises adhering the elements together via a layer of a heatvulcanisable rubber having the following properties:

a. a Mooney viscosity. after 4 minutes at 100C of 24 70 units b. a torque after 1 minute at 160C of l-3O inch.lbs.

c. a scorch time of not greater than 3 /2 minutes d. a vulcanisation rate of 9-20 inch.lbs. per minute e. a time to 100% cure of 10-30 minutes, and

f. a quality level of 50-90 inch.lbs.

Property (a) was measured using a Mooney viscometer and properties (b) to (f) using a Monsanto Rheometer type LSD fitted with micro dies.

It is observed that other rubber compositions which have properties which do not fulfil all the above conditions are of little value in adhering ingot mould hot topping slabs since they tend to adhere the slabs insufficiently well, especially to hot and cambered or uneven ingot moulds or head boxes. The method of the present invention is of particular value in adhering flexible deformable not very resilient hot top lining slabs, but can be used with the more rigid types.

The rubber may be present between the slab and the mould or head box surface in the form ofa plurality of strips of material extending across the slab or a thick rubbery mass, eg a single sheet of rubber material may cover the whole area of the slab.

Thus, for example, tapes of unvulcanised rubber of width 6-50 mm and thickness 0.7 1.5 mm. preferably about 1mm may be used.

Alternatively, sheets of calendered rubber 100-600 mm wide and 0.25 2.0 mm (preferably 0.36 0.5 mm) thick may be used.

The total area of slab covered by the rubber tape or sheet material may vary from 10-1007: and is preferably 15-40%. Similarly the sheet may be made up from a plurality of tapes.

The preferred method of attachment of the rubber tape or sheet to the hot top lining slabis first to prime the surface of the slab with a suitable primer. and then apply the tape or sheet while the primer is still wet. Preferred primers for use in this connection are solutions or dispersions of rubber. most preferably a rubber similar in constitution to that of the tapes or sheet. It is possible in some cases to adhere the rubber tape or sheet by "autohesion after the primer has dried. but this is sometimes rendered ineffective by the presence of sulphur bloom on the tape or sheet. Application while the primer is still wet overcomes this difficulty.

The adhesion of the rubber tape or strip to the mould or head box wall is preferably by means of a tacky pressure-sensitive adhesive material. Polymers of 2- ethylhexyl acrylate which are available commercially as adhesive materials are the adhesives of choice for this purpose, though other poly (acrylic ester) materials may also be used.

In order to promote adhesion between the lining slab and the rubber tape or sheet. the surface of the lining slab may be contoured appropriately. e.g.. by dimpling, e.g., depressions spiked into the slab surface which increase the area of contact of the primer solution. Furthermore, the surface of the slab may advantageously be relieved by grooves. These aid the escape of gases generated in the slab and in its fixing system during casting. Likewise, the surface of the rubber sheet or tape material may be flat or corrugated or otherwise textured, e.g., by embossing. Any known surface treatment process for effecting these may be used.

The adhesive and rubber sheet or tape material used should possess sufficient bonding and tensile strength to hold the slab in place at temperatures up to 300C, and this strength should be developed on application of the slab to the ingot mould or head box wall.

It is found that the temperature rangeof the substrate over which the rubber sheet or tape material will adhere may vary with the type of rubber used, and in such cases, in order to provide ingot hot top slabs which are attachable to mould surfaces at very widely differing temperatures, it may in some cases be desirable to provide rubber sheet or tape material of more than one type on the slab surface; for example, alternate tapes of synthetic and natural rubber, each having the properr ties noted above may be used.

Suitable rubber stocks for use in the present invention include natural rubber, butyl and nitrile rubbers and neoprene rubber. Of these types, nitrile rubbers are not preferred since the temperatures undergone by ingot mould hot top slabs in use may decompose the rubber and give rise to noxious fume. The rubber sheet or tape material may be a solid rubber or it may be of blown, expanded or foamed rubbery material. The rubber sheet or tape material is preferably formed of a rubber composition including customary fillers, extenders and the like to produce a satisfactory product.

In practice, the most convenient way of putting the invention into effect is to extrude a strip of wet primer onto the rear surface of a slab, (i.e., the non-moltenmetal contacting surface), adhering a suitable length of rubber tape to the wet primed slab, and then subsequently pressing the slab onto the ingot mould or head box wall via an intermediate layer of adhesive. In this respect a plurality of stripes of wet primer may be laid 3 down followed by a corresponding number of rubber tapes.

The lengths of tape may be coated with a layer of adhesive on one side and for the purposes of ease of stor agethe thus coated rubber tapes may be coiled up with an interleaved release paper strip. Alternatively. unco'ated rubber tapes may be applied to the wet primed slab and the adhesive applied either before the slabs are despatched or immediately prior to the slabs being at tached to the desired site.

,It is naturally, preferable in such a case to ensure that the tapes have a sufficient storage life after manufacture. Anti-oxidants and other additives may be included to ensure this. Commercially, for use in lining ingot mould heads and head boxes, a shelf life of 3 months is desirable, both as stored tape and when applied to a hot topping slab.

.In an alternate method, the tapes are not preformed as such and then attached to the surface; they may be extruded onto a primed or unprimed surface in the form of a strip of extruded composition which subsequently cures (e.g. by heat or solvent evaporation) to give a rubber tape compound firmly adhered to the sur face.

Most preferably, the primer comprises, in solution in a suitable solvent, a rubber composition of the type defined above for the tapes, and a tackifying agent. The preferred solvents are chlorinated hydrocarbon solvents, e.g., dichloromethane, dichloroethane, trichlo- ,roethylene, 1,1 ,l-trichloroethane, tetrachloroethylene.

Mixtures of such solvents may be used, in order to adjust, if required, solvent evaporation rate and/or the depth of penetration of the primer through the backing surface of the tile.

The primer solution preferably comprises -40% total solids, depending upon the viscosity required. The preferred method of applying the primer is flow under gravity through a die plate. However, the primers may be of thin sprayable consistency, medium brushing consistency, or of thick consistency for application by ex trusion by suitable means, e.g., an extrusion head, a squeeze bottle or a grease-gun" type of applicator.

The viscosity of the primer solution may be varied by changing the total solids content, and the evaporation rate may be varied by using any of the different solvents mentioned above either singly or in admixture.

The tackifying agent is preferably a coumaroneindene resin. The weight ratio of rubbery material to tackifying agent in the primer is preferably from l:l to 10:1, the former giving a very highly tacky primer film.

The primers may be made up by merely mixing the ingredients together, e.g., in a Z-blade mixer. The

primer may then be applied to the slab backing in strips corresponding to the disposition of the rubber strips to be subsequently applied.

The primer is applied to the backing at suitable application rate e.g., 50-150 gms/ft of area of surface primed, and the unvulcanised rubber tape, coated on one side only with the previously mentioned pressure sensitive adhesive, is then applied to the wet rubber primed surface ofthe slab, uncoated (pressure sensitive adhesive-free) side toward the primed surface. This is best done by rolling the tape with pressure on to the primed surface, the uppermost surface (adhesive coated side) being protected with siliconised release paper.

The assembly is now allowed to dry and it is found that a very strong bond has formed between the dried primer film of tackified rubber and the unvulcanised rubber tape, so that primer and rubber tape form virtually an integral material, and that the primer is adhered tenaciously to the slab. So adhered, the rubber tape and slab are very securely adherent to each other. being resistant to high shear forces in plane parallel to that of the slab, and high transverse tensile forces in directions perpendicular thereto, over a temperature range of 0. to 300C.

Typical examples of suitable primer compositions are:

20 parts by weight 880 parts by weight Coumarone-indcnc liquid resin Dichloromethane This formulation is of low viscosity suitable for spray application.

3. Natural unvulcanised rubber compound (tape material) Coumaronc-indene resin Dichloromethane 200 parts by weight 40 parts by weight 880 parts by weight This formulation is a higher viscosity formula. This is suitable for hand extrusion through a flexible aluminium or polythene tube or bottle, or extrusion by mechanical means.

If necessary, for specialised adhesion applications, the unvulcanised rubber tape compound itself may be tackified by the addition of 5-25 parts of coumarone resin per parts of the basic formulation. This tackification of the tape itself increases the adhesion of the tape on to the primed surface.

It is also observed that the heat vulcanisable rubber materials, for example tapes and sheets, used in the method of the present invention may also be employed for a variety of other purposes for fixing together two like or dissimilar materials. Such adhesion may be accomplished at temperatures from below OC to 400C.

The accompanying drawing shows, in part cutaway perspective view, a hot top lining slab according to the present invention adhered in position.

Referring to the drawing, a lining slab 1 has a plurality of grooves 2 in its back and is also dimpled as at 3. Across the back of the slabs are strips of dried down primer 4 onto which are adhered tapes of rubber 5. These tapes are adhered to the surface of a head box by a thin layer of a polymerised Z-ethyl-hexyl-acrylate adhesive 6.

The following are examples of two suitable formulations for. making vulcanisable rubber tapes for use in the present invention, Parts are given by weight.

EXAMPLE 1 A suitable Neoprene rubber formulation is as follows:

parts Neoprene WRT (ex DuPont) l()() (Polymer) Light magnesium oxide 4 (Acid accelerator) SRF Carbon Black 60 (Filler) Dutrex R (ex Shell) 11) (Softening oil) Stearic acid 0.5 (Cure activator) Z-mercapto imidazolinc 0.75 (Cure accelerator) Zinc oxide 5 (Curing agent) Properties of this formulation are as follows:

a) viscosity (4 min. 100C) 50 units b) torque (160C. 1 min) 29 inch.lb. c) scorch time 2% min. d) vulcanisation rate 1 1 inch.lb/min time to 100% cure 30 min. f) quality level 85 inch.lb.

EXAMPLE 11 A suitable natural rubber formulation is as follows:

Natural rubber (Ribbed parts smoked sheets grade 1 100 (polymer) Zinc oxide (Cure activator) Stearic acid 3 (Cure activator) Carbon black (Cabot carbon) 50 (Filler) Octaminc (a diisobutyleneldiphenyb amine reaction product) 1 (Anti-oxidant) di-2-benzthiazyl disulphide 1 C ure accelerator) Sulphur 3 (Curing agent) Properties of this formulation were as follows:

a) Mooney viscosity (4 min, 100C) 25 units b) torque (160C. 1 min) 20 inch.lb. c) scorch time 2 mins. d) vulcanising rate 14 inch.lb./min. e) time to 100% cure mins. f) quality level 60 inch.lb.

We claim:

1. A method of adhering a plurality of elements, which comprises adhering together an insulator in the form of a hot top lining slab to an inner metal surface of an ingot mould or a head box via a layer of a heat-vulcanisable rubber having the following properties:

a. a Mooney viscosity, after 4 minutes at 100C of 24-70 units;

b. a torque after 1 minute at 160C of l30 inch.lbs.;

c. a scorch time of not greater than 3 /2minutes;

d. a vulcanisation rate of 9-20 inch.lbs. per minute;

e. a time to 100% cure of 10-30 minutes, and

f. a quality level of 50-90 inch.lbs. WE CLAIM:

2. A method according to claim 1 wherein a surface of one of the elements is first primed with a solution or dispersion of a rubber and then heat-vulcanisable rubber is applied to the primed surface while the primer is still wet.

3. A method according to claim 2 wherein the rubber has substantially the constitution of the subsequently applied heat-vulcanisable rubber.

4. A method according to claim 2 wherein the solu tion or dispersion comprises a tackifying agent.

5. A method according to claim 4 wherein the weight ratio of rubberztackifyingagent in the solution or dispersion is from 1:1 to 10:1. 1

6. A method according to claim 2 wherein the primer is applied at a coating weight from 50 to 150 gm.ft.'

7. A method according to claim 2 wherein the primed element is the hot top lining slab and in which a tacky pressure-sensitive adhesive material is utilized to bind the rubber to the inner surface of the ingot mould or head box.

8. A method according to claim 7 wherein the adhesive material is a polymer of an acrylic ester.

9. A method according to claim 1 wherein the heat-vulcanisable rubber is utilised as a plurality of strips extending across the surface of one of the elements.

10. A method according to claim 9 wherein at least two such strips are of different rubbers, each different rubber having the properties defined in claim 1.

11. A method according to claim 1 wherein the heat-vulcanisable rubber is utilised as a single sheet.

12. A method according to claim 1 wherein the heat-vulcanisable rubber covers from 15 to 40% of the area of the surface to which it is applied.

13. A method according to claim 1 wherein the heat-vulcanisable rubber is a natural, butyl or neoprene rubber.

14. A method of adhering a hot top lining slab to an inner surface of an ingot mould or head box, which method comprises first priming the rear surface of the lining slab with a solution comprising a rubber and a tackifier; then extruding a plurality of strips of a heat-vulcanisable rubber having the following properties:

a. a Mooney viscosity, after 4 minutes at C of 2470 units;

b. a torque after 1 minute at 160C of 1-30 inch.lbs.;

c. a scorch time of not greater than 3 /2 minutes:

(1. a vulcanisation rate of 9-20 inch.lbs. per minute;

e. a time to 100% cure of 10-30 minutes, and

f. a quality level of 5090 inch.lbs. onto the primed surface while the primer is still wet; a1- lowing the assembly to cure to give a rubber strip firmly adhered to the surface; and adhering the rubber strip to the inner surface of the ingot mould or head box with a tacky pressure sensitive material.

15. A hot top lining insulator slab assembly prepared by first priming the rear surface of the lining slab with a solution comprising a rubber and a tackifier; then extruding a plurality of strips of a heat-vulcanisable rubber having the following properties:

a. a Mooney viscosity, after 4 minutes at 100C of 24-7O units;

a torque after 1 minute at 160C of inch.lbs; a scorch time of not greater than 3V2minutes;

a vulcanisation rate of 920 inch.lbs. per minute; a time to 100% cure of 10-30 minutes, and

a quality level of 50-90 inch.lbs. onto the primed surface while the primer is still wet: allowing the assembly to cure to give a rubber strip firmly adhered to the surface.

16. A method of adhering a plurality of elements, which comprises adhering together an insulator in the form of a hot top lining slab to an inner metal surface of an ingot mould or a head box via a layer of a heat-vulcanisable rubber in the form of a plurality of strips extending across the surface of one of the elec. a scorch time of not greater than 3 /2 minutes; ments. said rubber having the following properties; d. u vulcanisation rate of 9-20 inch.lbs. per minute;

a. a Mooney viscosity, after 4 minutes at 100C of e. a time to 100% cure of 10-30 minutes. and

24-7O units; f. a quality level of 50-90 inch.lbs.

* l l =l b. a torque after 1 minute at 160C of 1-30 inch.lbs.; 5

Claims

1. A METHOD OF ADHERING A PLURAITY OF ELEMENTS, WHICH COMPRISES ADHERING TOGETHER AN INSULATOR IN THE FORM OF A HOT TOP LINING SLAB TO AN INNER METAL SURFACE OF AN INGOT MOULD OR A HEAD BOX VIA A LAYER OF A HEAT-VULCANISABLE RUBBER HAVING THE FOLLOWING PROPERTIES: A. A MOONEY VISCOSITY, AFTER 4 MINUTES AT 100*C OF 24-70 UNITS, B. A TORQUE AFTER 1 MINUTE AT 160*C OF 1-30 INCH.LBS., C. A SCORCH TIME OF NOT GREATER THAN 3 1/2 MINUTES, D. A VULCANISATION RATE OF 9-20 INCH.LBS. PER MINUTE, E. A TIME TO 100% CURE OF 10-30 MINUTES, AND F. A QUALITY LEVEL OF 50-90 INCH.LBS. WE CLAIM:

4. A method according to claim 2 wherein the solution or dispersion comprises a tackifying agent.

5. A method according to claim 4 wherein the weight ratio of rubber:tackifying agent in the solution or dispersion is from 1:1 to 10:1.

6. A method according to claim 2 wherein the primer is applied at a coating weight from 50 to 150 gm.ft. 2.

14. A METHOD OF ADHERING A HOT TOP LINING SLAB TO AN INNER SURFACE OF AN INGOT MOULD OR BOX, WHICH METHOD COMPRISES FIRST PRIMING THE REAR SURFACE OF THE LINING SLAB WITH A SOLUTION COMPRISING A RUBBER AND A TACKIFIER, THEN EXTRUDING A PLURALITY OF STRIPS OF A HEAT-VULCANISABLE RUBBER HAVING THE FOLLOWING PROPERTIES: A. A MOONEY VISCOSITY, AFTER 4 MINUTES AT 100*C OF 24-70 UNITS, B. A TORQUE AFTER 1 MINUTE AT 160*C OF 1-30 INCH.LBS., C. A SCORCH TIME OF NOT GREATER THAN 3 1/2 MINUTES, D. A VULCANISATION RATE OF 9-20% INCH.LBS. PER MINUTE, E. A TIME TO 100% CURE OF 10-30 MINUTES, AND F. A QUALITY LEVEL OF 50-90 INCH.LBS. ONTO THE PRIMED SURFACE WHILE THE PRIMER IS STILL WET, ALLOWING THE ASSEMBLY TO CURE TO GIVE A RUBBER STRIP FIRMLY ADHERED TO THE SRFACE, AND ADHERING THE RUBBER STRIP TO THE INNER SURFACE OF THE INGOT MOULD OR HEAD BOX WITH A TACKY PRESSURE SENSITIVE MATERIAL.

15. A hot top lining insulator slab assembly prepared by first priming the rear surface of the lining slab with a solution comprising a rubber and a tackifier; then extruding a plurality of strips of a heat-vulcanisable rubber having the following properties: a. a Mooney viscosity, after 4 minutes at 100*C of 24-70 units; b. a torque after 1 minute at 160*C of 130 inch.lbs; c. a scorch time of not greater than 3 1/2 minutes; d. a vulcanisation rate of 9-20 inch.lbs. per minute; e. a time to 100% cure of 10-30 minutes, and f. a quality level of 50-90 inch.lbs. onto the primed surface while the primer is still wet; allowing the assembly to cure to give a rubber strip firmly adhered to the surface.

16. A method of adhering a plurality of elements, which comprises adhering together an insulator in the form of a hot top lining slab to an inner metal surface of an ingot mould or a head box via a layer of a heat-vulcanisable rubber in the form of a plurality of strips extending across the surface of one of the elements, said rubber having the following properties; a. a Mooney viscosity, after 4 minutes at 100*C of 24-70 units; b. a torque after 1 minute at 160*C of 1-30 inch.lbs.; c. a scorch time of not greater than 3 1/2 minutes; d. a vulcanisation rate of 9-20 inch.lbs. per minute; e. a time to 100% cure of 10-30 minutes, and f. a quality level of 50-90 inch.lbs.