Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/182—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents
  • C08G59/184—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents with amines
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/50—Amines
  • C08G59/5033—Amines aromatic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/50—Amines
  • C08G59/56—Amines together with other curing agents

Definitions

• the invention relates generally to phenalkamine and salted amine blends, and more particularly, to phenalkamine and salted amine blends as epoxy resin curing agents suitable for curing epoxy resins under low temperature curing conditions.
• Phenalkamines are epoxy hardening agents comprised of cardanol, formaldehyde, and an organic diamine.
• Cardanol is produced from Cashew Nutshell Liquid (CNSL).
• Phenalkamine may be produced via a Mannich reaction to produce a low molecular weight polymer by condensing one mol of alkyl phenol, two mols of formaldehyde and two mols of a polyamine.
• the polyamine may be aromatic or aliphatic.
• ethylene diamine and diethylenetriamine are used to produce Cardolite NC541 and Cardolite NC 540, respectively.
• Phenalkamines are products of the reaction (condensation products) of cardanol (I), which, chemically, is a C 15 alkylphenol and a major constituent of the oil obtainable from CNSL, with aliphatic (primary or secondary) amines and formaldehyde.
• the condensation step is carried out by first adding formaldehyde to the reaction, in the presence of at least a catalytic amount of an amine, thereby producing an alkyl Ci 5 phenol methylol pre-polymer, followed by condensation with a polyamine, which releases water.
• the temperature during synthesis should be less than 90°C to minimize color development.
• Crude CNSL predominantly contains anacardic acid (II).
• the distillation of CNSL in the presence of acid gives a composition which mainly contains cardanol and, as a secondary product, cardol (III), see, for example, U.S. Patent No. 6,262,148, and U.S. Patent No. 6,229,054. It has been found that the distillation of crude CNSL provides a composition which mainly contains cardanol and, as a secondary product, cardol and small quantities of 2-methyl cardol and anacardic acid.
• the cardanol/cardol mixture thus obtained has three technical disadvantages:
• the resulting product is effective as an epoxy hardener, but it has a dark color, based on the Gardner scale, of greater than 12.
• the dark color in the existing product is due to impurities, including cardols (a di-hydroxy alkyl phenol) which lead to rapid polymerization and oxidation reactions, which generate precursor color bodies, either during storage or during phenalkamine manufacturing.
• cardols a di-hydroxy alkyl phenol
• Current manufacturing processes do not separate the cardol impurities at a satisfactory level in which no darkening occurs.
• the curing speed is slow.
• a curing agent for epoxy resins includes: a phenalkamine blended with a salted polyamine or a salted polyamine-epoxy adduct to form a curing agent for an epoxy resin, wherein at least one- third of the primary amine groups of the salted polyamine or the salted polyamine- epoxy adduct are blocked.
• a method for making a curing agent for epoxy resins includes the steps of: providing a phenalkamine, and blending the phenalkamine with a salted polyamine or a salted polyamine-epoxy adduct to form a curing agent for an epoxy resin, wherein at least one-third of the primary amine groups of the salted polyamine or the salted polyamine-epoxy adduct are blocked.
• a method for curing epoxy resins at reduced temperatures includes the step of: adding the curing agent described herein to an epoxy resin, wherein curing occurs at temperatures between about -10°C to about 25°C.
• a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to the expressly listed elements, but may include other elements inherent, or not expressly listed, to such process, method, article, or apparatus.
• the term “or” refers to an inclusive “or” and not to an exclusive “or”.
• the condition A "or” B is satisfied by any one of the following: A is true (included) and B is false (omitted); A is false (omitted) and B is true (included); and both A and B are true (both included).
• the phenalkamines are prepared with substantially pure cardanol.
• the cardanol is prepared by substantially removing oligomers (with molecular weights of 1,000 to 3,000) from the crude CNSL by distillation, including simple short-path distillation (rapid completion of process to suppress or minimize secondary processes, such as polymerization or oxidation). During distillation, about 15% to 20% by weight of the CNSL is removed in the form of oligomers.
• Short-path distillation may be conducted as follows.
• Step 1 First runnings of 2% to 5% by weight (based on the CNSL used) are removed at temperatures of 150°C to 200 0 C and at pressures of 1-5 mmHg, followed by a main fraction at temperatures of 22O 0 C to 260 0 C and pressures of 1-5 mmHg.
• This main fraction (the distillate from step 1) is referred to as crude cardanol.
• Step 2 The distillate from Step 1 is reacted with boric acid (H 3 BO 3 ), to convert the dihydric phenols present into the corresponding boric acid esters.
• the molar ratio of crude cardanol from Step 1 to boric acid may be adjusted to a ratio of 3:0.07 to 3:0.1.
• the reaction temperature may be adjusted to a range of about 120 0 C to about 15O 0 C.
• the reaction time is between 30 and 90 minutes. Water formed during the reaction may be continuously removed from the system.
• the amount of boric acid used is a stoichiometric quantity in relation to the cardols present in the crude cardanol from Step 1.
• Step 3 The mixture from Step 2 is subjected to distillation in which the low-boiling constituents are removed, and the relatively high molecular weight boric acid esters remain in the residue. Distillation may be conducted in vacuo under the conditions of a short-path distillation or a conventional fractional distillation.
• the main fraction of Step 3 may be treated with small quantities of adsorbents and/or reducing agents.
• suitable reducing agents include, but are not limited to: sodium hydrosulfite (Na 2 S 2 O 4 ), sodium metabisulfite (Na 2 S 2 Os), sodium borohydride (NaBH 4 ), lithium aluminum hydride (LiAlH 4 ), tin chloride (SnCl 2 ) or magnesium silicate.
• suitable adsorbents include, but are not limited to, magnesium silicate, or chemically-equivalent compounds.
• the quantity of adsorbents or reducing agents used may be from 0.1% to 5% by weight (based on the main fraction obtained in Step 3).
• the distillate in Step 2 may be reacted with acetic anhydride, to bind unwanted chromophores.
• the quantity of acetic anhydride used may be from about 1% to 5% by weight, based on the distillate, and the reaction temperature may be adjusted to about 50 0 C to 70 0 C.
• the acetic acid formed may be continuously removed (stripped off) from the system. The resulting mixture is subjected to fractional distillation.
• a fractionating column with more than 6 theoretical plates may be used for fractional distillation.
• a typical fractionating column with a head, rectifying section, feed plate, stripping section and bottom is used for the continuous fractional distillation.
• the cardanols are removed at the upper end (head) of the column, and the cardols at the lower end (bottom).
• the distillation is carried out at temperatures ranging from 180°C-210°C/0.5-1.5 mmHg at the head of the fractionating column and 230°C-260°C/1.5-3 mmHg at the lower end of the column.
• the product stream at the lower end of the column contains a fraction which is rich in cardols and contains only small amounts of cardanols and acetic acid esters.
• the cardanols used according to an aspect of the invention have a purity of greater than 98%, where cardols are present at less than 0.2%.
• high-purity cardanols that are substantially free of cardols, in combination with a salted polyamine or a polyamine-epoxy adduct, viscosity is lower due to the reduced quantity of cardols present.
• the polyamines may be any amine having two or more primary amine functionalities, including compounds having secondary amine functionalities in addition to the two or more primary amine groups.
• Suitable diamines and polyamines are represented by the formula:
• R 3 and R 4 are divalent hydrocarbyl groups, with 2 to 20 carbon atoms, and m and n are integers ranging from 0 to 5, wherein m + n is equal to at least 1.
• the hydrocarbyl groups may be branched or linear alkylene groups, cycloaliphatic groups or contain aromatic groups, provided the attached amines are primary or secondary aliphatic amines.
• diamines and polyamines include, but are not limited to: ethyleneamines such as 1 ,2-ethanediamine (EDA), N-(2-aminoethyl)-l,2-ethanediamine (DETA), N,N-bis(2-amino-ethyl)-l,2-ethanediamine (TETA), N-(2-aminoethyl)-N'-[(2- amino-ethyl)amino-ethyl]-l,2-ethanediamine (TEPA), aminoethylpiperazine, and higher polyethylenepolyamines, 1,3-benzenedimethanamine (MXDA- metaxylylene diamine); 1,3-cyclohexanedimethanamine (1,3-BAC); 1,2-diaminocyclohexane (DACH); norbornanediamine; isophorone diamine; 5-amino-l,3,3-trimethylcyclo- hexanemethanamine (IPDA); trimethylhexamethylene
• Epoxy- functional materials suitable for preparing the polyamine-epoxy adducts include, but are not limited to: Bisphenol A epoxy resins, including the diglycidyl ether of Bisphenol-A with epoxy equivalent weights ranging from 170-525; Bisphenol F epoxy resins, including the diglycidyl ether of Bisphenol F with epoxy equivalent weights ranging from 156-190; Bisphenol F epoxy novolac resins; cresol epoxy novolac resins; and various mono-, di- and tri-functional reactive epoxy "diluents,” such as butyl glycidyl ether, C 8-I0 alkyl glycidyl ethers, Ci 2-I3 alkyl glycidyl ethers, Ci 2-14 alkyl glycidyl ethers, cresyl glycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and resorcino
• the epoxy-functional materials are reacted with a diamine or polyamine, to form a polyamine-epoxy adduct.
• the reaction can be conducted at a temperature of from 20 0 C to 80 0 C or higher, depending on the selection of reactants.
• the adducts may be prepared by conventional methods.
• Salted amines useful as epoxy curing agent modifiers for the phenalkamines are those where at least one-third of the primary amine groups are blocked by reacting with an epoxy, or are "salted” by adding an acidic hydrogen donor group. This modification of an amine-functional epoxy curing agent has been found to be very resistant to reaction with atmospheric carbon dioxide and moisture to produce the bicarbonates or carbamates characterized as the undesirable amine "blush".
• curing agents also exhibit rapid cure response when reacted with epoxy resins and other epoxy-functional materials, and that by selecting the proper components, the systems exhibit excellent cure characteristics at significantly lower temperatures than previously attained. If an amine adduct produced by the reaction of diamines and/or polylamines with an epoxy resin or other epoxy-functional materials is further reacted with sufficient acidic hydrogen donor groups to block or "salt", at least one-third, and, alternatively, may be about one-half, of most or all of the remaining primary amine groups, the curing agent thus produced also does not exhibit reaction with atmospheric carbon dioxide and moisture, and also exhibits excellent low temperature cure characteristics.
• the curing agents of the invention are present in an amount effective to cure the epoxy resin.
• accelerators are not required, but may be utilized to further increase the cure rate of the epoxy resin system.
• Various amine-compatible accelerators can be used, provided the accelerators are soluble in the curing agent.
• suitable accelerators include, but are not limited to: 2,4,6-tris-(dimethylaminomethyl)phenol, N,N-di-ethylethanol- amine, and N,N-dimethylbenzylamine.
• the concentrations of the accelerators may be from 0.1% to 10%, based on the weight of the curing agent.
• a curable epoxy resin may have a 1,2-epoxy equivalency of one or more, and preferably, on the average, about 1.5 or more epoxide groups per molecule.
• the epoxy resin may be saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, aromatic or heterocyclic, and may also have substituents, such as bromine, which do not materially interfere with the curing reaction.
• the epoxy resin may be monomeric or polymeric, liquid or solid, but is preferably liquid at room temperature.
• Suitable epoxy resins include glycidyl ethers prepared by reacting epichlorohydrin with a compound containing at least one, and preferably two or more, hydroxyl groups carried out under alkaline reaction conditions.
• suitable epoxy resins include, but are not limited to: polyglycidyl ethers of polyhydric phenols, epoxy novolacs or similar glycidated polyphenols resins, polyglycidyl ethers of alcohols, glycols or polyglycols, and polyglycidyl esters of polycarboxylic acids.
• a particularly suitable epoxy resin is based on a polyglycidyl ether of a polyhydric phenol.
• Polyglycidyl ethers of polyhydric phenols can be produced, for example, by reacting an epihalohydrin with a polyhydric phenol in the presence of an alkali.
• suitable polyhydric phenols include, but are not limited to: 2,2- bis(4-hydroxyphenyl) propane (Bisphenol-A); 2,2-bis(4-hydroxy-3-tert-butylphenyl) propane; l,l-bis(4-hydroxyphenyl) ethane; l,l-bis(4-hydroxyphenyl) isobutane; bis(2- hydroxy-l-naphthyl)methane; 1,5-dihydroxynaphthalene; and l,l-bis(4-hydroxy-3- alkylphenyl) ethane.
• Suitable polyhydric phenols can also be obtained from the reaction of phenol with aldehydes such as formaldehyde (Bisphenol-F). Fusion products of these polyglycidyl ethers of polyhydric phenols with phenolic compounds such as Bisphenol-A are also suitable as epoxy resins, such as those described in U.S. Patent No. 3,477,990 and U.S. Patent No. 4,734,468.
• Commercial examples of preferred epoxy resins include, for example, EPON® Resins 862, 828, 826, 825 and 1001 available from Hexion Specialty Chemicals and commercially available epoxy resins from Dow Chemical Company such as DERTM330; 331; 354; 661; and 671.
• the epoxy resins may also be blended with a glycidyl ether of an aliphatic or aromatic alcohol, glycol or polyglycol, or a glycidyl ester of a monocarboxylic acid.
• a glycidyl ether of an aliphatic or aromatic alcohol glycol or polyglycol
• a glycidyl ester of a monocarboxylic acid examples include, but are not limited to: butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, 1,4-butanediol diglycidyl ether, and the glycidyl ester of neodecanoic acid.
• the glycidyl ethers and esters may be blended with an epoxy resin in amount of from 1% to 50% in order to affect wetting characteristics, viscosity, flexibility, adhesion characteristics, and other properties.
• EPON® Resins 815, 813, and 8132 available from Hexion Specialty Chemicals
• DERTM 324 available from Dow Chemical Company
• the curing agent or the epoxy resin system can be diluted with minor amounts of compatible solvents, including, but not limited to, aliphatic or aromatic hydrocarbons, alcohols, glycol ethers, ketones, and esters.
• compatible solvents including, but not limited to, aliphatic or aromatic hydrocarbons, alcohols, glycol ethers, ketones, and esters.
• the components of the curing agent according to an aspect of the invention may be present in ratios of 95:5; 90:10; and 80:20, depending upon the desired application.
• the curing agent may contain auxiliaries and additives, for example, flow control additives, antifoam agents, or anti-sag agents.
• Other additives may include pigments, reinforcing agents, fillers, elastomers, stabilizers, extenders, plasticizers, or flame retardants, depending upon the intended application.
• Other conventional additives that do not materially affect the basic characteristics and efficacy of the composition may also be present.
• the epoxy resin curing composition may be used in applications including, but not limited to: adhesives, coatings, flooring, casting, and encapsulants.
• increasing the curing speed at ambient conditions allows for quick return to service of the substrate being coated with an epoxy system.
• Increasing the curing speed at low temperatures provides the ability to coat products under adverse environmental conditions and helps extend the paint season of an epoxy resin system. If such fast curing systems can also avoid blush, which is a white powdery coating on top of an epoxy film formed due to insoluble carbonate formed by reaction of free primary amines with carbon dioxide in the presence of moisture, then intercoat adhesion failures can also be avoided.
• all technical and scientific terms used herein have the same meaning commonly understood by one of ordinary skill in the art to which the invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, suitable methods and materials are described below. The materials, methods and examples are illustrative only, and are not intended to be limiting.
• a suitable reactor is charged with 5.60 mols of cardanol, and 0.58 mols of DETA.
• Example 3 950 grams of phenalkamine obtained from Example 1 was combined with 50 grams of the salted amine obtained from Example 2.
• Example 2 900 grams of phenalkamine obtained from Example 1 was combined with 100 grams of the salted amine obtained from Example 2.
• the control in Table 1 is the phenalkamine of Example 1, and does not include the salted amine of Example 2.
• a salted amine to a phenalkamine, in various ratios, i.e., 95:5; 90:10; and 85:5, advantageously provides a curing agent with reduced dry time at 25°C, and also at 0 0 C.
• the dry times performance shows a major improvement at 25°C with 55% reduction in through-cure time, a major factor in how quickly a coated part can be put back into service.
• the improvement is also seen at 0 0 C, which is indicative of the performance improvement in outdoor coating applications on bridges, tanks, pipelines and ships in cold climates.

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• Epoxy Resins (AREA)

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• 2008
  • 2008-12-10 EP EP08864160A patent/EP2222747B1/en active Active
  • 2008-12-10 ES ES08864160T patent/ES2394553T3/es active Active
  • 2008-12-10 JP JP2010538414A patent/JP5431355B2/ja not_active Expired - Fee Related
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