NO164910B - Epoxy novolac resin composition. - Google Patents

Description

The present invention relates to epoxy-novolac resins, more specifically an epoxy-novolac resin material with an average epoxy functionality of 3-12.

High functionality (average functionality 5-8) epoxy novolac resins have high Tg values when cured with sulfanilimide. However, they are very difficult to manufacture due to the high viscosity of the novolak resin precursors. The present invention is aimed at epoxy-novolac resins which have high Tg values when cured with typical epoxy curing agents, for example methylenedianiline, diaminodiphenylsulfone, sulfanilimide and the like, while also having a relatively low melt viscosity.

The present invention thus concerns an epoxy-novolac resin which has an average epoxy functionality of 3-12 and is represented by the formula

wherein each A is independently a divalent hydrocarbon group of 1-14, preferably 1-8, carbon atoms; each R is independently hydrogen, a halogen atom, a hydroxyl group or a hydrocarbon group with 1-9, preferably 1-4, carbon atoms, each R' independently being hydrogen or an alkyl group with 1-4 carbon atoms, and n has an average value of 1- 10. The characteristic is that (a) when 2-functional and 3-functional components are present and R

is hydrogen, then the weight ratio of 2-functional component to 3-functional component is less than 1.1:1, preferably less than 0.75:1, most preferably less than 0.5:1; (b) when 2-functional and 3-functional components are present and each R is independently a halogen atom, a hydroxyl group or a hydrocarbon group of 1-9, preferably 1-4, carbon atoms, then the weight ratio of the 2-functional component and the 3-functional component less than 0.5:1; (c) when the mean

epoxy functionality is from 3 to 5, the resin contains less than 12.5, preferably less than 7, wt% of 2-functional component; and (d) when the average epoxy functionality is from 5 to 12, the resin contains less than 9, preferably less than 5, wt% 2-functional component.

With the expression "2-functional component" as used here, is meant the part of the novolak resin or epoxy novolak resin where n has a value of zero.

With the expression "3-functional component" as used here, is meant the part of the novolak resin or epoxy novolak resin where n has a value of 1.

With the expression "average functionality" as used here, is meant the average number of aromatic hydroxyl groups per molecule.

The following examples are illustrative of the present invention.

TEST METHODS

The following test methods were used in the examples.

MOLECULAR WEIGHT was determined using standard gel permeation chromatography (GPC) methods using polystyrene standards for molecular weight calibration.

GLASS TRANSITION TEMPERATURE (Tg) was determined using a DuPont 1090 analyzer with differential scanning calorimetry (DSC) model 912 for Tg up to approx. 250°C.

For Tg values >250°C, a DuPont model 943 thermal mechanical analyzer (TMA) was used.

SOFTENING POINTS were determined using a softening point (MSP) apparatus model Mettler FP-53.

FRACTURE TOUGHNESS MEASUREMENT (G1C)

The method for measuring G^c (fracture toughness or "critical stress energy release rate") is an adaptation of ASTM E-399 plastics from its original use on metals. The compact tensile test is now in widespread use and is described in J. Mater. Sei., Vol. 16, 2657, 1981. An individual test piece is cut approximately 1" (25.4 mm) square from a flat casting, usually 1/8" (3.175 mm) thick. A dovetail notch is cut at one end, centered, approx. 1/4" (6.25 mm) in depth. A razor blade is then inserted into this notch and tapped to produce a pre-break. Two holes are drilled as close to the dovetail as specified in ASTM E-399, allowing the specimen to be stapled into position in the Instron testing machine. Stretching the specimen now allows the required force to propagate opening of the prebreak to be measured, using a test speed of 0.02"/minute (0.0085 mm/sec). This force is used in the equation given in ASTM E-399, along with the required specimen dimensions and the appropriate pre-break length, to calculate a "stress intensification factor" Kq. This is then combined with tensile modulus (in cases where tensile modulus was not measured, a value of 300,000 psi (2.07 GPa) was used) and Poisson's ratio for the material to give the value for G1C, usually reported in erg/cm<2 > x 10^. A scale comparing typical values of G1C for various plastics and metals is given in Lee, L.H., "Physicochemical Aspects of Polymer Surfaces", K.L. Mittal, published by Plenum Press, New York, N.Y., 1983.

EXAMPLE 1

A. Production of phenol/formaldehyde-novolac resin

A novolak resin was prepared by reacting 2.89 parts phenol, 1.0 part 37% formalin and 0.0018 part oxalic acid to produce a resin with a Mettler softening point of 74.1, melt viscosity at 150°C of 100 cP . Analysis by gel permeation chromatography (GPC) showed that the product had a weight medium M.V. on 813, a number of means M.V. of 583, with a polydispersity of 1.40. The product contained 24.98% by weight of 2-functional components and 17.18% by weight of 3-functional components for a ratio of 2-functional to 3-functional components of 1.24:1.

B. Removal of 2-functional product

The phenol/formaldehyde novolak resin prepared above was repeatedly extracted with boiling water until the 2-functional content was less than 1% by weight.

C. Preparation of epoxy novolak resin

The product from Example 1-B, 206 grams, was dissolved in 925 grams of epichlorohydrin, 484.7 grams of isopropanol and 78.6 grams of water. This mixture was then heated to 70°C, and 360 grams of 20% aqueous sodium hydroxide was added over approximately 45 minutes (2700 seconds). The reaction mixture was digested at this temperature for an additional 15 minutes (900 s). The water phase was then separated and discarded. 160 grams of 20% aqueous sodium hydroxide was added to the mixture at 70°C over approximately 20-30 minutes (1200-1800 s). The reaction was digested for an additional 15-20 minutes (900-1200 s) at 70°C and then cooled. The aqueous layer was separated, and the organic layer was repeatedly washed with water until it was free of salt and sodium hydroxide. Additional epichlorohydrin, 462 grams, was added during the washing steps to aid in the separation. The product was obtained by removing excess epichlorohydrin and solvent via vacuum distillation. The semi-solid epoxy resin product had an epoxy content of 23.3%, an epoxy equivalent weight of 184.5 and a hydrolyzable chloride content of 51 ppm.

EXAMPLE 2

A. Production of phenol/formaldehyde novolak resin

A portion of the novolak resin prepared in Example 1-A was used.

B. Preparation of epoxy novolak

Using the method described in Example 1-C, a portion of extracted novolak resin (206 grams) was reacted with 925 grams of epichlorohydrin in 498 grams of isopropanol and 80.4 grams of water. After separation of the water phase, a further 32 grams of sodium hydroxide was dissolved in 128 grams of water added in the second step. The epoxy product had an epoxide equivalent weight of 179.4, a hydrolyzable chloride content of 768 ppm, a Mettler softening point of 53.5°C, and a melt viscosity of 100 cP (0.1 Pa-s) at 150°C. The weight mediator M.V. was 1,106, number means M.V. 719 and the polydispersity 1.54. The average epoxy functionality was calculated as 4.0. The 2-functional and 3-functional content were respectively 10.50 and 12.65% by weight, so that there was a ratio of 0.83:1.

EXAMPLE 3

A. Production of phenol/formaldehyde novolak

A portion of the novolak resin from Example 1-A was used.

B. Preparation of epoxy novolak

Using the same method as described in example 1-C, 425.9 grams of the above-mentioned novolak were reacted with 1894.0 grams of epichlorohydrin in 1019.8 grams of isopropanol using 1065.2 grams of 20% aqueous sodium hydroxide. The epoxy novolac had an epoxy equivalent weight of 177.9. The weight mediator M.V. was 1,309, number means M.V. 862 and the polydispersity 1.46. The average epoxy functionality was calculated to be 4.8. The 2-functional content was 2.29% against 9.9% for the 3-functional product, which in a weight ratio between 2-functional and 3-functional of 0.23:1.

EXAMPLE 4

A. Production of phenol/formaldehyde-novolac resin

A glass reactor equipped with stirrer, reflux condenser, addition funnel and device for controlling the temperature was charged with 550 grams (5.85 moles) of phenol and 2.75 grams (0.03 moles) of oxalic acid. This mixture was heated to 110°C, and 298.8 grams (3.68 moles) of 37% formalin was added slowly over 60 minutes (3600 s). The reaction mixture was allowed to boil under reflux during the formalin addition and for approx. 60 minutes (3600 s) thereafter. Vacuum was then applied and the excess phenol and water were removed by vacuum distillation at a final temperature of 180°C.

The solid novolak resin had a Mettler softening point of 87.9°C, analysis by gel permeation chromatography (GPC) showed that the product has a weighting agent M.V. of 1,044, a number average M.V. of 700, with polydispersity 1.49. The product contained 16.3% 2-functional components, and the ratio between 2-functional and 3-functional was 1.2:1.0.

B. Preparation<g> of epoxy-novolac resin

Using the exact same procedure as described in Example 1-C, 307 grams of the product from Example 4-B were reacted with 767.0 grams of 20% aqueous caustic in 1365.3 grams of epichlorohydrin, 735.1 grams of isopropanol and 118 .7 grams of water. The product had an MSP of 81.3°C, a melt viscosity of 589 cP (0.589 pa-s), measured at 150°C, and an epoxy equivalent weight of 186.1. The ratio of 2-functional to 3-functional components was less than 0.5:1.

EXAMPLE 5

A. Production of phenol/formaldehyde-novolac resin

Application of the method described in example 4-A. 1506.6 grams (16.03 moles) of phenol were reacted with 831.56 grams (10.26 moles) of 37% formalin using 7.53 grams (0.084 moles) of oxalic acid. The solid product had a Mettler softening point of 90.7°C. The 2-functional content was 15.27%, measured by GPC. Weight means M.V. was 1,098, number means M.V. 714 and the polydispersity 1.54. The product contained 15.27% by weight of 2-functional components, and a 3-functional component content of 12.67% by weight, i.e. a ratio between 2-functional and 3-functional components of 1.2:1.

B. Removal of 2-functional product

A portion of the product prepared above was continuously extracted with water of approx. 99°C until the 2-functional content was 4.26% by weight, measured by GPC. The solid product had a Mettler softening point of 108.9°C. The weight mediator M.V. was 1,263, number means M.V. 895, with polydispersity 1.41. The ratio of 2-functional to 3-functional components was 0.40:1.

C. Removal of 2-functional product

Another portion of the novolak resin prepared in Example 5-A was continuously extracted with water until the 2-functional content was less than 0.5% by weight, as measured by GPC. The Mettler softening point was 128°C. The weight mediator M.V. was 1,446, number means M.V. 1,138 and polydispersity 1.27. The ratio of 2-functional to 3-functional components was less than 0.25:1.0.

D. Preparation of epoxy vnovolac

A portion of the resin prepared in Example 5-B,

402.5 grams, was reacted with 1789.9 grams of epichlorohydrin in 963.8 grams of isopropanol and 155.6 grams of water using 1006.4 grams of 20% aqueous caustic as described in example 1-C. The product had an epoxy equivalent weight of 185. The weight mediator M.V. was 1,481, the numerical average M.V. 935 and the polydispersity 1.58. The average epoxy functionality was calculated to be 5.1. The 2-functional content was 3.81%. The weight ratio of 2-functional to 3-functional components was less than 0.25:1.

E. Preparation of epoxy vnovolac

A portion of the resin prepared in Example 5-C,

385.3 grams, was reacted with 1713.6 grams of epichlorohydrin in 922.7 grams of isopropanol and 149 grams of water using 964.6 grams of 20% aqueous caustic as described in example 1-C. The product was a brittle, non-sintering solid with an MSP of 85°C and an epoxide content of 23% (an epoxide equivalent weight of 187). Weight means M.V. was 1,719, number means M.V. 1,234 and the polydispersity 1.39. The average epoxy functionality was calculated to be 6.6. The 2-functional content was less than 0.5%. The ratio of 2-functional to 3-functional components was less than 0.25:1.0.

EXAMPLE 6

A. Production of phenol/formaldehyde novolak resin

Using the method described in example 4-A, 3000 grams (31.88 mol) of phenol were reacted with 1655.96 grams

(20.4 mol) of 37% formalin using 15.0 grams (0.167 mol) of oxalic acid. The solid resin obtained had a Mettler softening point of 92.7, melt viscosity 380 cP at 150°C. By GPC analysis, the weighted average was M.N. 1,168, the number average M.V. 753, with a polydispersity of 1.55. The resin contained 16.67 wt% 2-functional component and

13.43 wt% 3-functional component. The weight ratio between 2-functional and 3-functional components was 1.24:1.

B. Removal of 2-functional product

A portion of the above product was continuously extracted with water of approximately 99°C until the 2-functional content was 0.36% by weight, measured by HPLC. By GPC analysis, the weighted average was M.V. 1,452, the number average M.V. 1,123, with a polydispersity of 1.29. The ratio of 2-functional to 3-functional components was less than 0.25:1.

C. Removal of 2-functional product

Another portion of the novolak resin prepared in Example 6-A was continuously extracted with hot water until the 2-functional content was 0.73% by weight, as measured by HPLC. The resin had a weight mediator M.V. of 1,427, a number average M.V. of 1,090, with a polydispersity of 1.31. The product had a weight ratio between 2-functional and 3-functional components of 0.25:1.

D. Preparation of epoxy vnovolac

A portion of the novolak resin from Example 6-B, 425 grams, was reacted with epichlorohydrin using exactly the same ratios of reactants and conditions as described in Example 8-B. The product was a non-sintering, brittle solid with an MSP of 86.0°C. The melt viscosity was 850 cP, measured at 150°C. The product had an epoxy equivalent weight of 184.0. The weight mediator M.V. was 1,775, number means M.V. 1,203, with a polydispersity of 1.48. The average epoxy functionality was calculated to be 6.5. The ratio of 2-functional to 3-functional content was less than 0.25:1.

E. Preparation of epoxy novolac

A portion of the novolak resin from Example 6-C, 425.0 grams, was reacted exactly as described in Example 9-D to give a brittle, solid resin with an epoxy equivalent weight of 184.6. The weight mediator M.V. was 1,789, number means M.V. 1,187, with a polydispersity of 1.41. The average epoxy functionality was calculated to be 6.4. The 2-functional content was 0.73% by weight, and the weight ratio between 2-functional and 3-functional content was less than 0.25:1.

COMPARISON ATTEMPT

A. Preparation of epoxy-novolac resin

A portion of the resin from Example 6-A, 104 grams was dissolved in 462.5 grams of epichlorohydrin, and 2.3 grams of 60% aqueous benzyltrimethylammonium chloride solution added. This solution was stirred under a nitrogen atmosphere for 72 hours (259,200 s) at 70°C, then cooled to 20°C, and 312.5 grams of a 16% solution of sodium hydroxide/9% sodium carbonate and stirred at 20°C in 90 minutes (5400 s). The aqueous layer was separated, and an additional 312.5 grams of 16% sodium hydroxide/9% sodium carbonate solution and stirred for 30 minutes (1800 seconds) at 20°C. The aqueous layer was separated, and the organic layer was washed with water until it was free of salt and caustic. Excess epichlorohydrin was then removed via vacuum distillation at 150°C. The product had an epoxide content of 24.9% (an epoxide equivalent weight of 172.7). The 2-functional content was 13.4%. The weight mediator M.V. was 1,531, and the number average M.V. was 729, with a polydispersity of 1.71. The average epoxy functionality was calculated to be 4.2. The ratio between 2-functional and 3-functional components was 1.30.

Claims (3)

1. Epoxy-novolac resin material with an average epoxy functionality of 3-12, represented by the following formula: where A is independently a divalent hydrocarbon group having 1-14 carbon atoms; each R is independently hydrogen, a halogen atom, a hydroxyl group or a hydrocarbon group having 1-9 carbon atoms; each R' is independently hydrogen or an alkyl group having 1-4 carbon atoms, and n has an average value of 1-10, characterized in that (a) when 2-functional and 3-functional components are present and R is hydrogen, then the weight ratio of the 2-functional component to the 3-functional component is less than 1.1:1; (b) when 2-functional and 3-functional components are present and each R is independently a halogen atom, a hydroxyl group or a hydrocarbon group having 1-9 carbon atoms, then the weight ratio of the 2-functional component to the 3-functional component is less than 0.5:1; (c) when the average epoxy functionality is from 3 to 5, then the resin contains less than 12.5% by weight of the 2-functional component; and (d) when the average epoxy functionality is from 5 to 12, then the resin contains less than 9% by weight of the 2-functional component. 2. Epoxy-novolac resin material as set forth in claim 1, characterized by the conditions that (a) when 2-functional and 3-functional components are present and R is hydrogen, then the weight ratio between the 2-functional component and the 3- functional component less than 0.75:1; (b) when 2-functional and 3-functional components are present and each R is independently a halogen atom, a hydroxyl group or a hydrocarbon group having 1-9 carbon atoms, then the weight ratio of the 2-functional component to the 3-functional component is less than 0.5:1; (c) when the average epoxy functionality is from 3 to 5, then the resin contains less than 7% by weight of the 2-functional component; and (d) when the average epoxy functionality is from 5 to 12, then the resin contains less than 5% by weight of the 2-functional component. 3. Epoxy-novolac resin material as stated in claim 2, characterized by the premise that when 2-functional and 3-functional components are present and R is hydrogen, the weight ratio between the 2-functional component and the 3-functional component is less than 0.5:1.