CA2647967A1

CA2647967A1 - Epoxy resin compositions and curing agents for thermally insulating ultra-deep sea equipment used for oil and gas production

Info

Publication number: CA2647967A1
Application number: CA 2647967
Authority: CA
Inventors: Unknown
Original assignee: Shawcor Ltd
Current assignee: Individual
Priority date: 2008-12-19
Filing date: 2008-12-19
Publication date: 2010-06-19
Also published as: WO2010069049A1

Description

EPOXY RESIN COMPOSITIONS AND CURING AGENTS FOR
THERMALLY INSULATING ULTRA-DEEP SEA EQUIPMENT USED

FOR OIL AND GAS PRODUCTION

The present invention relates to curable liquid epoxy resin compositions, liquid curing agent compositions for curable liquid epoxy resins and to epoxy resin compositions formed therefrom which are especially, although not exclusively, suited for forming thermal insulation on subsea oil and gas well production equipment, especially in the form of syntactic foam insulations comprising insulating microspheres dispersed in an epoxy polymer matrix.

Known compositions of which the applicants are aware have required complex and laborious installation procedures, have resulted in syntactic foams that tend to degrade in service, have been brittle and rigid and easily damaged, and have low maximum operating temperatures and insulation properties that are not as effective as is desirable. Further, known compositions have produced products that have a higher rate of water adsorption than may be considered desirable when exposed to hot high pressure subsea conditions.

In one aspect of the present invention, there is provided a curable liquid epoxy resin composition that is a blend comprising, in percentages by weight based on the total weight of the composition:

(A) 15 to 85%, preferably 20 to 70%, more preferably 30 to 60% of a bifunctional liquid curable epoxy resin having two epoxide groups per molecule;

(B) 0 to 50%, preferably 7 to 50%, more preferably 10 to 40%, still more preferably 15 to 35%, of a bi- or trifuncitonal liquid curable epoxy resin having two or three epoxide groups per molecule which when blended with (A) imparts increased tensile elongation to the cured product thereof; and (C) 0.5 to 15%, preferably 0.7 to 12%, more preferably 1 to 10% liquid curable epoxide functional silicone polymer.

In preferred embodiments of the invention, the resin composition can be used to form cured resin compositions that have improved flexibility and hydrothermal properties as compared with known resins.

The bifunctional epoxy resin performs the function of a base resin that improves the water adsorption properties and thermal stability of the cured product of the composition.
Compositions containing less than 15% of the bifunctional epoxy resin tend to have inadequate water adsorption and thermal stability properties while compositions containing greater than 85% of the bifunctional resin do not have appreciably improved water adsorption or thermal stability properties, and tend to have poor tensile elongation and flexibility properties.
In a preferred form, the bifunctional resin comprises an aliphatic, aromatic, alicyclic or heterocyclic epoxy resin, or a blend thereof. A preferred epoxy resin is bisphenol A epoxy resin, such as Shell EPON 825, Dow D.E.R. 330, Dow D.E.R. 331, Dow D.E.R. 332, or Dow D.E.R. 383, or bisphenol F epoxy resin such as Dow D.E.R. 354.

Above mentioned optionally present component (B) may in a preferred form be a bi- or trifunctional liquid curable epoxy resin that is known to provide increased tensile elongation to products formed by blending component (B) with component (A).
In this respect, such bi- or trifunctional epoxy resin (B), when substituted for a portion of the bifunctional epoxy resin (A) provides improved tensile elongation as compared to a similar composition containing no bi- or trifuctional liquid epoxy resin (B), when cured with the same curing agent under the same cure conditions.

The cured product of compositions containing greater than about 50% of the bi- or trifunctional liquid resin, when present, do not have appreciably improved tensile elongation properties as compared with those having lesser contents of the bi- or trifunctional curable resin.

Cured compositions resulting from resin compositions containing less than about 7% of the bi- or trifunctional liquid resin, when present, tend to have reduced thermal stability and lower tensile elongation properties, but can still have adequate properties for use in numerous deep water insulation applications.

Preferred bi- and trifunctional liquid curable epoxy resin components used in the present invention also improve the thermal stability of the resulting cured product.

Examples of bi- or trifunctional liquid epoxy resins usable in the composition of the invention include epiclorohydrin polyglycol (the reaction product of epiclorohydrin and polypropylene glycol), for example Dow D.E.R. 732, difunctional reactive diluent based on neopentyl glycol, for example Epodil 749 available from Air Products and Chemicals, Inc., propoxylated glycerin triglycidyl ether, such as Erisys GE-36, available from CVC Thermoset Specialties, Morristown, New Jersey, and epoxidized neopentyl glycol modified with liquid butidiene-acrylonitrile rubber, such as HyPox RM20, available from CVC Thermoset Specialties.

As noted above, preferred embodiments of the curable epoxy resin composition of the invention include 0.5 to 15% by weight liquid curable epoxide functional silicone polymer.
The epoxide functional silicone polymer serves to increase the flexibility of the cured product, as measured by tensile elongation, and also improves the thermal stability of the product. Compositions containing less than about 0.5% by weight of the silicone polymer tend to have flexibility and thermostability properties that may be less than desirable for some applications, while contents of greater than about 15% of the silicone polymer tend to result in the product having a water absorption value that may be considered excessively high. Further, since the silicone polymer is relatively poorly compatible with the bifunctional liquid epoxy resin, there may be problems of lack of homogeneity of the blended composition if greater than about 15% of the silicone polymer as employed.

Examples of liquid curable expoxide functional silicone polymers useful in the composition of the invention include trifunctional silicone prepolymers such as Silmer EP C50, multi-epoxide functional silicone prepolymers such as Silmer EP J10, linear difunctional epoxide terminated silicone prepolymers such as Silmer EP Di-100 and Silmer EP Di-50. All the Silmer polymers are available from Siltech Corporation, Toronto, Canada.
In a second aspect, the present invention provides a liquid curing agent composition for curable liquid epoxy resin, comprising in percents by weight based on the total weight of the composition:
(K) 5 to 60%, preferably 7 to 40% and more preferably 10 to 30% liquid polyamide;
(L) 5 to 80%, preferably 7 to 70%, more preferably 10 to 60% liquid polyamine; and (M) 10 to 90%, preferably 17 to 80%, more preferably 25 to 70% liquid aliphatic or cycloaliphatic amine.

When cured with conventional curing agents, the liquid epoxy resin composition of the invention provides improved flexibility and hydrothermal properties as compared with known epoxy resin compositions. However, when cured with the liquid curing composition according to the second aspect of the present invention, the resulting cured compositions provide still further enhanced physical properties, particularly improved flexibility. Moreover, the curing agent composition according to the second aspect of the invention imparts improved physical properties, particularly improved flexibility, as measured by tensile elongation, to conventional curable liquid epoxy compositions, as compared with the products obtained from such compositions when cured with conventional curing agents.

Further, it has been found that all three components K,L
and M are necessary in order to provide improved physical properties to the cured compositions, particularly tensile elongation properties. If any one of the three components, K, L or M is omitted, cured compositions that are obtained have inferior physical properties, particularly inferior tensile elongation properties.

Curing compositions containing less than 5% liquid polyamide or liquid polyamine, or less than 10% liquid aliphatic or cycloaliphatic amine tend to provide in use cured compositions that have inferior physical properties, particularly inferior tensile elongation properties. Further, the aliphatic or cycloaliphatic amine component ordinarily requires elevated temperature to effect curing. The combination of liquid polyamide and liquid polyamine tends to create an exothermic curing reaction which assists in promoting the curing action of the aliphatic or cycloaliphatic amine. If less than 5% liquid polyamide and less than 5%
liquid polyamine are present, the curing compositions tend to provide insufficient exothermic reaction to promote the curing action of the cycloaliphatic amine.

Curing compositions containing more than 60% liquid polyamide, more than about 80% liquid polyamine or more than 90% liquid aliphatic or cycloaliphatic amine do not result in significantly improved physical properties for the resulting cured compositions as compared with curing compositions containing lesser quantities of these components.

In a still further aspect of the present invention there is provided an epoxy resin composition or kit that comprises the curable liquid epoxy resin composition according to the first aspect of the present invention blended with or stored separately from and in association with the liquid curing agent composition according to the second aspect of the present invention.

In a preferred form, the curable compositions in accordance with the invention are employed in syntactic foam insulation compositions comprising insulating microspheres dispersed with the resin composition. If less than about 7%
by weight of the microspheres are employed, based on the total weight of the composition the resulting foam insulation tends to provide inadequate heat insulating properties, may tend to have poor compressive strength and may generate excessive exothermic heat during curing.

The use of greater than about 70% by weight of the mircospheres tends to produce foam insulation products that have inadequate strength properties. Preferably, the content of the microspheres is about 10 to 60% by weight, more preferably about 15 to 50% by weight, based on the total weight of the composition.
The microspheres may be any of the known microspheres useful for forming syntactic foam insulation compositions, for example ceramic microspheres or glass microspheres. Glass microspheres are preferred, by reason of their excellent insulation and strength properties. An example of microspheres that may be employed in the present composition are Scotchlite S38 microspheres, available from 3M
Corporation.

In the case in which the microspheres are glass microspheres, the resin composition preferably contains a coupling agent that promotes glass to resin coupling, in order to improve the strength characteristics of the cured foam insulation product. Various glass to resin coupling agents are known, such as alkoxysilanes, for example Silane Z-6040 available from Dow Corning, Silquest A-187 from GE Silicones, Dynasylan GYLMO from Evonik and KBM-403 from Shin-Etsu Chemical Co. In order to provide an adequate coupling effect, preferably the composition comprises at least about 0.5% of the coupling agent, based on the total weight of the composition. Further, compositions containing less than about 0.5 coupling agent tend to have poor (high) water adsorption properties. Contents of greater than about 10% of the coupling agent do not appear to appreciably improve the coupling effect, and may in fact impart the mechanical properties of the resulting cured syntactic foam composition.
Preferably, the content of the coupling agent is about 0.7% to 7%, more preferably 1 to 5%, based on the total weight of the composition.

In a preferred form, the epoxy resin compositions of the invention comprise a defoamer agent that tends to avoid air entrapment when the components of the composition are blended together. The presence of air within the mixture tends to result in a cured product having low strength and poor (high) water adsorption properties.

Compositions containing less than about 0.05% of the defoamer agent may tend to result in the composition entrapping excessive quantities of air, leading to the strength and water adsorption problems referred to above.
Compositions containing greater than about 10% of the defoamer agent, based on the total weight of the composition do not appreciably improve the exclusion of entrapped air in the compositions, and may in fact result in poorer physical properties in the cured resin composition. More preferably, the composition contains about 0.07 to about 7%, still more preferably about 0.1 to about 5% of the defoamer agent, based on the total weight of the composition.

Suitable defoamer agents include polydimethylsiloxanes, such as SAG 47, available from Chemtura, SAG 100 from GE
Silicones, EFKA-2722 and EFKA-8203 from EFKA.

Preferred compositions in accordance with the invention provide an injectable/castable/moldable syntactic foam system similar to urethane syntactic foam which can be cured at ambient condition with an adequate cure time (within a few hours). Such system exhibits many advantageous properties which make the composition suitable for use on deepsea oil and gas production equipment, e.g. manifolds, jumpers, and Xmas trees. The insulated material is high temperature resistant, and can withstand operating temperature at least 130 C up to 150 C.

The preferred composition is an injection molding system which can be molded into any desired shape. The composition is allowed to be cured at ambient temperature with substrate preheat to 60 - 80 C. The resulting insulation material has a thermal conductivity of 0.16 - 0.18 W/mK, tensile elongation of 5% - 10% and acceptable strength to withstand high pressure (for subsea depths >2000 m) and high temperature (operating temperature at 150 C). It has excellent adhesion to steel, epoxy, urethane or phenolic typed primers, urethane syntactic foam and surface treated polypropylene.

As noted above, in a preferred form, glass microspheres are used to provide low thermal conductivity, high strength, low weight, and low cost for the syntactic foam. The preferred glass microspheres have minimal breakage during the application/processing of the epoxy binder. In addition, the glass microspheres are strong enough to withstand the pressure caused by the depth of seawater. Preferably, 3M Scotchlite glass bubbles are used, including Scotchlite S32, S35, S38, S38HS, S42 and S60. The volume of glass microspheres to the total volume is preferably between 20-50% (35%).

While the above description provides ample information to permit one skilled in the art to make and use the present compositions, for the avoidance of doubt some detailed non-limiting Examples will be given.

Blending and Application/molding procedures:
Example 1 Preparation of resin with glass microspheres 45 kg curable liquid epoxy resin composition was prepared as follows:

21.35 kg D.E.R. 330 (Dow Chemical, U.S.A) was mixed with propoxylated glycerin triglycidyl ether (11.74 kg, Erisys GE
36, CVC Specialty Chemicals, U.S.A), epoxide modified siloxane (1.76 kg, Silmer EP C50, Siltech Corp, C.A.N.), 0.05 kg of SAG
47 polydimethylsiloxane (modified) anti-foaming surfactant (Chemtura), and 0.32 kg of alkoxysilane (Silane Z-6040, Dow Corning) at 550 rpm using a vacuum mixer at room temperature.
Glass microballoons (9.79 kg, Scotchlite S38) were added into the mixture. Additional 10 minutes mixing at 550 rpm was applied. The mixture could be stored in drums/pails for future use.

The viscosity of the resin was determined using Brookfield viscometer; the value was between 20,000 to 40,000 centipoises at 20 C.

Example 2 Preparation of liquid hardener 45 kg of hardener was prepared as follows:

23.48 kg modified polyamine (Aradur 3275BD, Huntsman, U.S.A) was mixed with cycloaliphatic amine (12.44 kg, Ancamine 2167, Air Products, U.S.A) and 9.08 kg polyamide curing agent (Ancamide 801, Air Products, U.S.A) at 550 rpm, RT. The mixture could be stored in drums/pails for future use.
The viscosity of the hardener was determined using Brookfield viscometer; the value is between 600 to 900 centipoises at 20 C.

Example 3 Cast-in-place resin composition A 100 liter mold was prepared as follows:

The substrate and the mold were preheated to 60 - 80 C.
Glass fiber insulation was wrapped on the outside of the mold.
The 2-component system (products of Examples 1 and 2) was applied by a conventional plural component equipment. 61.15 kg of curable resin component was heated to 60 C to bring the viscosity down to match the viscosity of the hardener. The resin and hardener were then pumped to a mixing chamber at a weight ratio 2.86:1 and the mixed material is injected into the mold. The demold time was approximately 3 hours.

Example 4 Table 1 An example of epoxy syntactic foam formulations.
Formulation Product Name Chemical Name (weight %) Resin (Part A) Propane, 2, 2-bis [p- (2, 3-D.E.R.330 epoxypropoxy)phenyl]-, 30.0 - 60.0 polymers Polyglycidyl Ether of ERISYS GE-36 15.0 - 35.0 Propoxylated Glycerin Glycidal ether modified Silmer EP C50 1.0 - 10.0 siloxane Silane Z-6040 Alkoxysilane 1.0 - 5.0 Sag 47 Polydimethylsiloxane 0.1 - 5.0 Scotchlite S38 Glass microsphere 15.0 - 50.0 Hardener (Part B) Ancamide 801 Polyamide 10 - 30 Aradur 3275BD Polyamine 10 - 60 Ancamine 2167 Cycloaliphatic Amine 25 - 70 Example 5 Simulated Service Test A Simulated Service Test (SST) was performed with the product of Example 3 under gradually increasing pipe internal temperature up to 150 C and pressure up to 3700 psi over 90 days. The thermal conductivity of the product increased slightly from 0.157 to 0.164 W/mK and % compressive creep was measured to be less than 2%. Listed below are the relevant thermal and mechanical properties of this material before and after SST.

Table 2 Properties of HTCC before and after SST.

Property Unit Before SST After SST
Compressive Strength MPa 32 30 Tensile Strength MPa 16 16 Tensile Elongation % 5.8 6.0 Thermal Conductivity W/mK 0.157 0.164 Density g/cc 0.835 0.840 Hardness Shore D 65 63 Water Absorption at % <1 n/a 4500 psi Water Absorption at % <5 n/a A certain amount of flexibility is desirable in an insulation material to accept bending and differential expansion under different conditions. Materials which have high rigidity may crack easily during molding process, handling or in service. Crack(s) in insulation can increase the possibility of convective heat losses and affect the overall insulating value of the system. Both flexibility and water absorption resistance of the composition of the present invention can be improved by using epoxy modified siloxane and a combination of flexible curing agents. Table 3 shows four examples (Examples 6 to 9) of epoxy syntactic foam binders:
with and without the use of epoxy modified siloxane. Their flexibility and water absorption resistance are characterized and summarized in Table 4. Examples 6 and 7 are cured with no flexible curing agents, whereas examples 8 and 9 are cured with a combination of flexible curing agents. When Examples 8 and 9 are compared to Examples 6 and 7, the elongation has a -70% increase and the % water absorption has decreased by -12%
with the use of Silmer EP C50. Although the elongation has not increased with the use of Silmer EP C50 for Examples 6 and 7 without flexible curing agents, the % water absorption has decreased over 50%.

Table 3 Examples of epoxy syntactic foam formulations Example 6 Example 7 Example 8 Example 9 Product Name Chemical name With Silmer No Silmer With No Silmer Silmer Propane, 2,2-bis [p-2,3-D.E.R.330 48.2 52.0 47.4 51.2 epoxypropoxy)phe nyl]-, polymers Polyglycidyl Ether of ERISYS GE-36 26.5 26.4 26.0 26.0 Propoxylated Glycerin Silmer EP Glycidal ether modified 4.0 0.0 4.0 0.0 siloxane Silane Z-Alkoxysilane 0.7 0.7 0.7 0.7 Polydimethylsilo Sag 47 0.1 0.1 0.1 0.1 xane Scotchlite Glass 20.5 20.7 21.8 22.0 S38 microsphere Ancamide 801 Polyamide 64.6 64.6 20.2 20.2 Aradur Polyamine 0 0 52.1 52.1 Ancamine Cycloaliphatic 35.4 35.4 27.7 27.7 2167 Amine Table 4 Properties of epoxy syntactic foam formulations with flexible curing agents.

Example 6 Example 7 Example 8 Example 9 Property With Silmer No Silmer With Silmer No Silmer Tensile Elongation 2.6 3.5 9.1 5.4 (%) Water Absorption at 7.4 15.7 11.8 13.4 100 C ($) Example 10 The thermal stability of the products of Examples 8 and 7 were compared using conventional thermal gravimetric analysis.

The accompanying drawing figure is a graph of weight against temperature showing the results.

Results Table 4 Sample Weight loss 1% 2% 5%, 10%
Without Silmer &

Flexible curing 292.5 C 319.8 C 340.0 C 360.5 C
agents With Silmer &

Flexible curing 320.0 C 341.2 C 363.1 C 378.3 C
agents The addition of Silmer EP C50 and the flexible curing agents delayed the thermal degradation of the formulation. As shown in Table 4, to reach same percentage of weight loss the temperature is over 20 C higher than the one without Silmer EP
C50 and the flexible curing agents.

The following test methods were used in the present specification.

= Compressive Strength (ASTM D1621) Compressive strength was measured by Toniprax Compressive Strength Tester as per ASTM D695 with modifications. Samples were cut in rectangular prism with dimensions 0.5" x 0.5" x 1.0". Samples were compressed at a speed of 1 mm/min to 10%
strain.

^ Tensile Elongation and Strength (ASTM D638) Tensile strength and % elongation were measured by Instron 4400R at a crosshead speed of 0.25"/min at 20 C.
Samples were cut in rectangular thin bar with dimensions 6" x 0.5" x 0.05". Tests were conducted as per ASTM D638 with modifications.

^ Thermal Conductivity (ASTM C518) The thermal conductivity or k-factor for SST test was determined using LaserComp Fox 50 Heat Flow Meter. The temperatures of the upper and lower plates were set at 70 C

and 50 C, respectively. Samples were prepared in cylinder with 2.25" diameter and 0.5" thickness.

^ Water Absorption at High Pressure Tests were conducted in an autoclave with 3% NaCl solution at 20 C and 4500 psi. Samples were prepared in 1" x 1" x 1" cubes. % Water absorptions at different test durations were determined by the weight changes of tested samples.

^ Water Absorption at 100 C

Specimens were in rectangular with dimension of 3'' x 1''x0.05''. Test was conducted in boiling water. The % of water absorption was determined by the weight changes during certain test duration.

Claims

1. A curable liquid epoxy resin composition that is a blend comprising, in percentages by weight based on the total weight of the composition:
(A) 15 to 85%, preferably 20 to 70%, more preferably 30 to 60% of a bifunctional liquid curable epoxy resin having two epoxide groups per molecule;

(B) 0 to 50%, preferably 7 to 50%, more preferably 10 to 40%, still more preferably 15 to 35%, of a bi- or trifunctional liquid curable epoxy resin having two or three epoxide groups per molecule which when blended with (A) imparts increased tensile elongation to the cured product thereof; and (C) 0.5 to 15%, preferably 0.7 to 12%, more preferably 1 to 10% liquid curable epoxide functional silicone polymer.

2. A liquid curing agent composition for curable liquid epoxy resin, comprising in percents by weight based on the total weight of the composition:
(K) 5 to 60%, preferably 7 to 40% and more preferably 10 to 30% liquid polyamide;

(L) 5 to 80%, preferably 7 to 70%, more preferably 10 to 60% liquid polyamine; and (M) 10 to 90%, preferably 17 to 80%, more preferably 25 to 70% liquid aliphatic or cycloaliphatic amine.

3. An epoxy resin composition or kit comprising a curable liquid epoxy resin composition as claimed in claim 1 blended with or stored separately from and in association with a liquid curing agent composition as claimed in claim 2.

4. A composition as claimed in claim 3 containing 7 to 70%, preferably 10 to 60%, more preferably 15 to 50%, insulating microspheres in percent by weight based on the total weight of the composition.

5. A composition as claimed in claim 4 wherein the microspheres are glass microspheres.

6. A composition as claimed in claim 5 including 0.5 to 10%, preferably 0.7 to 7%, more preferably 1 to 5% glass to resin coupling agent.

7. A composition as claimed in any one of claims 3 to 6 including 0.05 to 10%, preferably 0.07 to 7%, more preferably 0.1 to 5% defoamer agent for liquid resin composition.