WO2002072701A1

WO2002072701A1 - Improvements in insulating materials

Info

Publication number: WO2002072701A1
Application number: PCT/GB2002/000946
Authority: WO
Inventors: John Hargreaves; Matthew Miller
Original assignee: Hyperlast Limited
Priority date: 2001-03-08
Filing date: 2002-03-08
Publication date: 2002-09-19
Also published as: GB0105667D0

Abstract

Polyurethane precursor components are mixed on site immediately prior to or concurrently with application of the mixed and reacting polyurethane to a site of use, in separate mixing stages wherein in one stage at least one precursor component is mixed with glass or other microspheres, and in a second concurrent or immediately prior or subsequent mixing stage wherein the precursor components are mixed to form a polyurethane reaction mixture which is applied to the site of use. One or both of the precursor components may be mixed with the microspheres in the first mixing stage, and mixing stages may be performed together in a single mixing operation.

Description

IMPROVE ENTS IN INSULATING MATERIALS

This invention relates to improvements in insulating materials, and in

particular to methods for pre-use handling of thermal insulation materials for

pipes and structures for example in offshore gas or oil installations.

It is often necessary to provide thermal insulation for gas or oil pipes and flow lines used in petrochemical installations, both sub-sea, and also

onshore in high latitudes, to prevent excessive cooling of the product

flowing through the pipelines. Such cooling tends to adversely increase the

viscosity of liquid product and thus reduce the flow rate, even if

condensation of any fraction (such as water hydrates or waxes) from the

gas or oil stream is avoided.

Accordingly, it has become the practise to clad pipes and flow lines

particularly sub-sea, for liquid or gas petroleum products, in a jacket of a

synthetic plastics material which is several centimetres, typically 20-200

mm thick. This jacket is often made of a syntactic polyurethane

composition, that is a polyurethane composition, which includes a

substantial proportion of microspheres which may be plastics or glass spheres, these both in many cases being hollow microspheres sometimes

referred to as micro-balloons, of typical diameter 75 to 150 microns.

The practise to date has been for the polyol and diisocyanate

precursors of the polyurethane to be transported to the site of use in

separate containers, and then mixed at the point of use, and the reacting mixture either applied to the pipe in a moulding or casting operation, or used

to cast or mould shells to be used subsequently to clad such pipes, the

mixture in all cases reacting to a solid composition. The microspheres have

customarily been added by the formulator to the polyol precursor. The

alternative of adding the microspheres to the diisocyanate precursor whilst possible is contraindicated in many cases as the glass beads in particular

provide active hydroxyl (-OH) sites which during prolonged contact will

react to a significant extent with the diisocyanate, thereby reducing the

functionality of the diisocyanate precursor component.

A major problem, which has been encountered with the addition of

microspheres to the polyol component, results from the differences in

density of the liquid polyol component and the microspheres, and the delay encountered between formulation and use due to storage and long haul

transportation. Due to the lower density of the microspheres, these tend to

migrate to the top of the storage container and form a thick crust on the

polyol component. To enable the polyol component including the syntactic

microspheres to become useable it is necessary to break up the crust and

re-mix the microspheres with the liquid polyol, which is difficult and time consuming involving special on site mixing equipment, and is an unwelcome

burden on the user. It is an object of the invention to provide a method for

the pre-use handling of syntactic polyurethane precursor materials which

effectively solves the problem of separation of the microspheres component f rom the polyol component in transit or storage, and preferably allows more

microspheres to be added, giving better insulation properties to the resulting

composition.

According to the invention, a method of preparing a syntactic

polyurethane composition for use comprises a carrying out, immediately

prior to use, separate mixing steps one comprising mixing microspheres with

at least one precursor of the polyurethane compound, and another mixing

step comprising mixing the other precursor compound of the polyurethane

with said microspheres and first precursor compound and applying the

reacting mixture to the site of use.

Preferably said mixing steps are carried out concurrently, or said other

mixing step immediately before after said one mixing step, and the reacting

mixture is applied to the site of use as said other mixing step is proceeding

or immediately after completion of the other mixing step. The mixing steps,

and the step of applying the reacting mixture to the site of use are

preferably carried out continuously and concurrently in a continuous or

semi-continuous process.

In a first method according to the invention, the microspheres and a

cross-linker may be mixed in with the polyol precursor component in the

first mixing step, degassed and then the diisocyanate component added in

the second mixing step, and the mixed syntactic polyurethane passed to the

moulding step. In a variation of this method, the cross-linker may be added at the second mixing step instead of during the first mixing step. In a

second method according to the invention, both the polyol and the

diisocyanate components are mixed separately in the first mixing step with

microspheres, the mixtures are degassed, and then combined in the second

mixing step to provide a reacting polyurethane mixture which is then passed

to the application or moulding step. Cross-linker may again be added to the

polyol component in the first mixing step, or to the complete mixture in the second mixing step.

In a third method according to the invention, the polyol and

diisocyanate precursor components, and the microspheres and cross linker

may all be introduced to a mixer in a single mixing stage and blended in a

single mixing operation wherein the first and second mixing steps are

preformed together in a single stage, the mixture degassed and passed to

the moulding step. The polyol component may however be supplied pre-

blended with the cross linker.

The microspheres may comprise any of the types of microspheres

used for making syntactic compositions, for example, hollow plastic

microspheres, or hollow glass spheres, and ceramic beadlets .

The term "polyol precursor component" refers not only to polyol

materials suitable to form polyurethane's, but also amines, catalyst, pigment and other additives as used in the art to form polyurethane compositions

when mixed with suitable multifunctional isocyanates. A suitable mixer for carrying out each of the mixing stages to

incorporate the dry microspheres into a liquid component is available from

the Edge Sweets Company as the FFH System, and is described in US Patent No. 5332309. Another suitable mixer is supplied by Respecta-KWM

GmbH.

The invention will now be further described by way of example with

reference to the accompanying drawings, wherein Figures 1 to 5 are

diagrams illustrating five alternative methods according to the invention.

In accordance with the alternative preferred methods of the invention,

the components for the preparation of a syntactic polyurethane composition

are transported in separate containers to a location close to the site of use

for mixing at the location. The separate components comprise:-

1. A multifunctional isocyanate component, selected to produce a

desired polyurethane composition;

2. A polyol component, comprising one or more polyol's (diol or higher

which may also contain amines, catalyst, pigment and other additives),

selected to produce a desired polyurethane composition on reaction with the

selected isocyanate containing component;

3. A short chain low molecular weight component, reactive to

isocyanate, of functionality 2 or higher, (sometimes referred to as a cross

linker) which gives superior physical properties to the resultant

polyurethane's, (if used) 4. Microspheres, preferably hollow glass or plastics microspheres,

although other materials may as set out above be used.

As shown in figure 1 , a first method according to the invention

comprises feeding a polyol polyurethane precursor component via line 10 and hollow glass microspheres via line 1 1 to a mixer MIXER I, together with

preferably a cross linker component via line 12. The polyol, microspheres

and any cross linker are mixed in a mixer and fed by line 13 to a degasser

14, where as far as possible air and other entrained gasses are eliminated.

It is desirable to do this, as air bubbles trapped in the foam are, at sub-sea pressures compressed thereby reducing the thickness and insulating

capacity of the foam. After degassing, the mixture is passed via line 15 to

a second mixer MIXER II, where the isocyanate containing component is fed

in by line 16. Alternatively to being introduced at MIXER I, the cross-linker

component may be also fed to MIXER II, via line 17 (broken line). The

completed syntactic polyurethane mix, now beginning to react is fed via line

18 to the moulding step, to be completed within the time allowed by the reaction rate established by the polyurethane formulation.

In Fig 1 , if the materials from lines 15, 16 and 17 (if used) are

delivered to MIXER II in the correct proportions for forming the syntactic

polyurethane composition, then MIXER II can be simply a mixing device

otherwise mixer II can consist of a proportioning machine with short-term

storage tanks, proportioning pumps and a suitable mixing device. As shown in Figure 2, an alternative method according to the

invention comprises not only adding microspheres introduced by line 20 to a

mixer, MIXER I, with polyol component via line 21 and cross-linker

component via line 22; but also adding further microspheres via line 23, to the isocyanate containing component supplied by line 24 to a further mixer MIXER II. The mixed output from MIXER I is passed by line 25 to a

degasser 26, and by a line 27 to the third mixer MIXER III whilst the mixed

output from MIXER II is passed via line 28 to a degasser 29 and after

degassing by line 30 to the third mixer MIXER III. The output from Mixer ill

is then passed via line 31 to the moulding step, the polyurethane forming reaction having been initiated. An advantage of this method is that a higher total proportion of microspheres can be introduced into the formulation than

by adding the microspheres only to one component. In conventional batch

manufacture, due to the difficulties in the stability and separation of

isocyanate/microsphere blends it is usual only to add microspheres to the

polyol component. A factor limiting the proportions of microspheres, which

can be added to the polyol component, is the resultant viscosity of the

blend. By this method microspheres can also be added to the isocyanate

stream thus the total content of microspheres in the formulation can be

increased, and the effectiveness of the resultant polyurethane as thermal

insulation on the pipeline improved.

In Fig 2 if the materials from lines 27 and 30 are delivered to MIXER III in the correct proportions for forming the syntactic polyurethane

composition, then MIXER III can be simply a suitable mixing device.

Otherwise MIXER III can consist of a proportioning machine with short-term

storage tanks, proportioning pumps, and a suitable mixing device.

Figure 3 illustrates a yet further alternative method of the invention, wherein polyol component, microspheres, cross-linker component, and

diisocyanate component are all fed into a single mixer IV, via respective

lines 32, 33, 34 and 35. The mixed output from mixer 31 passes to

degasser 36 and hence to the moulding or casting step.

In figure 4 polyol, cross linker and diisocyanate components are fed

by respective lines 41 , 42, 43 to a mixer I, and the resulting mixture, which is beginning to react, is then fed via line 44 to mixer II where microspheres

are added via line 45.

The mixture of microspheres with the reacting polyurethane mix is

then fed by line 46 to a degasser 47, and after degassing supplied to the

moulding operation by line 48.

In a further embodiment illustrated in figure 5, polyol polyurethane

precursor component is fed by line 51 and cross linker by line 52 to a first

mixer, mixer I, and the resulting mixture fed to a second mixer, mixer II by

line 53, where it is mixed with microspheres which are added to the second

mixer via line 54. The mixture is then fed by line 55 to a degasser 56, and

after degassing by line 57 to a third mixer, mixer III, where the diisocyanate polyurethane precursor component is added to the mixture of polyol,

microspheres and cross linker, via line 58. The polyurethane forming

condensation reaction is now initiated and the reacting mixture is fed by line

59 to the moulding stage.

The mixers used in figures 1 to 3 may be as described in US Patent

No 5332309 and supplied by the Edge Sweets Company as the FFH

System. The mixers used in figures 4 and 5 may be as supplied by Respecta-KWM GmbH.

In any of the above methods, the cross linker maybe pre-blended into

the polyol component instead of being fed separately to the mixer. The

method according to the invention allows for syntactic polyurethane's to be

pre-compounded, and made up for transportation into separate, polyol and diisocyanate components, and with the microspheres or other filler, and a

cross-linker also to be kept separate, whilst avoiding the problem of

separation, which arises when microspheres are pre-incorporated into the

polyol component. A compact and transportable mixing unit, suitable for

mixing the polyurethane precursor components and the microspheres as a

dry filler, which can advantageously be a mixer according to the said US

Patent No. 5332309 such as the Edge Sweets Company FFH System, can

be made available, either to replace the wet mixer which would be needed

at the mixing site in any case to blend the precursor components into a

reaction mixture for the production of the polyurethane, or to feed the polyol side of such a wet mixer, thus providing syntactic insulation applied

either by moulding or casting directly onto lengths of oil or gas pipeline, or

by casting or moulding insulating shells to be used subsequently to clad oil

or gas pipelines. This avoids the need to reconstitute probably less

insulating polyol compositions, which have separated in the time between

manufacture of the polyol composition and its use in the moulding or

casting operation.

Claims

1. A method of preparing a syntactic polyurethane composition for use,

comprising a carrying out, immediately prior to use, a separate mixing

steps one comprising mixing microspheres with at least one precursor

of the polyurethane compound, and another mixing step comprising

mixing the other precursor compound of the polyurethane with said

microspheres and first precursor compound, and applying the reacting

mixture to the site of use.

2. A method according to claim 1 , wherein said one and other mixing

steps are carried out concurrently, or said other mixing step

immediately before or after said one mixing step and the reacting

mixture is applied to the site of use as said other mixing step is

proceeding or immediately after completion of said other mixing step.

3. A method according to claim 1 or 2 carried out at or close to the site

of use wherein said one and other mixing step and said step of

applying the reacting mixture are carried out continuously and

concurrently.

4. A method according to anyone of claims 1 to 3 wherein the

microspheres are mixed with the polyol precursor component in said

one mixing step and the diisocyanate component added thereto in

said other mixing step.

5. A method according to anyone of claims 1 to 3 wherein the polyol and the diisocyanate component are in said one mixing step, each

mixed separately with microspheres, and the resulting mixtures

combined in said other mixing step.

6. A method according to anyone of claims 1 to 3 wherein said one and

other mixing steps are performed together by mixing the polyol and

diisocyanate polyurethane precursor components and the

microspheres in a single stage.

7. A method according to any preceding claim wherein a cross-linker is

added during the said one step.

8. A method according to anyone of claims 1 to 6, wherein a cross-

linker is added during the other mixing step.