WO2016029450A1

WO2016029450A1 - Halogen-free epoxy formulations

Info

Publication number: WO2016029450A1
Application number: PCT/CN2014/085576
Authority: WO
Inventors: Jingjing YAN; Guihong LIAO; Hongyu Chen; Mark B. Wilson; Xiangyang Tai; Xiaorong He; Lu Zhu; Yanli FENG
Original assignee: Blue Cube Ip Llc
Priority date: 2014-08-29
Filing date: 2014-08-29
Publication date: 2016-03-03
Also published as: WO2016033136A1; TW201615740A

Abstract

A curable composition comprising a) an epoxy resin; and b) a hardener component comprising i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and ii) naphthol novolac, is disclosed. The curable composition can be used to prepare electrical laminates and printed circuit boards.

Description

FREE EPOXY FORMULATIONS

FIELD OF THE INVENTION

The present invention is related to epoxy resin compositions. More particularly, the present invention is related to halogen-free or substantially halogen-free formulations.

INTRODUCTION

Epoxy resins are widely used in coatings, adhesives, printed circuit boards, semiconductor encapsulants, adhesives and aerospace composites thanks to the excellent mechanical strength； chemical, moisture, and corrosion resistance； good thermal, adhesive, and electrical properties. Epoxy resins are inherently flammable, thus many phosphorous based flame retardants (such as phosphate, phosphazene, DOPO (9, 10-Dihydro-9-Oxa-10-Phosphaphenanthrene-10-Oxide), etc. ) have been employed to obtain flame retardancy due to fire safety and environmental concerns. However, the phosphorous based flame retardants may cause moisture uptake issues and sometimes result in cured resins with lower glass transition temperatures (T_g). Therefore, a non-halogen flame retardant (FR) epoxy composition, which offers not only good flame retardant performance but also higher T_g and moisture resistant properties, would be desirable.

SUMMARY

The instant invention is a curable composition comprising, consisting of, or consisting essentially of a) an epoxy resin； and b) a hardener component comprising i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and ii) naphthol novolac.

DETAILED DESCRIPTION

The instant invention is a curable composition. The instant invention is a curable composition comprising, consisting of, or consisting essentially of a) an epoxy resin； and b) a hardener component comprising i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and ii) naphthol novolac. The curable composition can further include optionally a filler selected from the group consisting of natural silica, fused silica, alumina, hydrated alumina, and combinations thereof. The curable composition can further include optionally a catalyst.

The curable composition comprises an epoxy resin and a hardener, as described in further details herein below.

The curable composition may further include one or more fillers. The curable composition may comprise 10 to 80 percent by weight of one or more fillers. All individual values and subranges from 10 to 80 weight percent are included herein and disclosed herein, for example, the weight percent of filler can be from a lower limit of 10, 12, 15, 20, or 25 weight percent to an upper limit of 62, 65, 70, 75, or 80 weight percent. For example, curable composition may comprise 15 to 75 percent by weight of one or more fillers； or in the alternative, curable composition may comprise 20 to 70 percent by weight of one or more fillers. Such fillers include, but are not limited to natural silica, fused silica, alumina, hydrated alumina, and combinations thereof.

The curable composition may further include one or more catalysts. The curable composition may comprise 0.01 to 20 percent by weight of one or more catalysts. All individual values and subranges from 0.01 to 20 weight percent are included herein and disclosed herein, for example, the weight percent of catalyst can be from a lower limit of 0.01, 0.03, 0.05, 0.07, or 1 weight percent to an upper limit of 2, 6, 8, 10, 15, or 20 weight percent. For example, curable composition may comprise 0.05 to 10 percent by weight of one or more catalysts； or in the alternative, curable composition may comprise 0.05 to 2 percent by weight of one or more catalysts. Such catalysts include, but are not limited to 2-methyl imidazole (2MI), 2-phenyl imidazole (2PI), 2-ethyl-4-methyl imidazole (2E4MI), 1-benzyl-2-phenylimidazole (1B2PZ), boric acid, triphenylphosphine (TPP), tetraphenylphosphonium-tetraphenylborate (TPP-k) and combinations thereof.

The curable composition may further include one or more tougheners. The curable composition may comprise 0.01 to 70 percent by weight of one or more tougheners. All individual values and subranges from 0.01 to 70 weight percent are included herein and disclosed herein, for example, the weight percent of toughener can be from a lower limit of 0.01, 0.05, 1, 1.5, or 2 weight percent to an upper limit of 15, 30, 50, 60, or 70 weight percent. For example, curable composition may comprise 1 to 50 percent by weight of one or more tougheners； or in the alternative, curable composition may comprise 2 to 30 percent by weight of one or more tougheners.

Such tougheners include, but are not limited to core shell rubbers. A core shell rubber is a polymer comprising a rubber particle core formed by a polymer comprising an elastomeric or rubbery polymer as a main ingredient and a shell layer formed by a polymer graft polymerized on the core. The shell layer partially or entirely covers the surface of the rubber particle core by graft polymerizing a monomer to the core. Generally the rubber particle core is constituted from acrylic or methacrylic acid ester monomers or diene (conjugated diene) monomers or vinyl monomers or siloxane type monomers and combinations thereof. The toughening agent may be selected from commercially available products； for example, Paraloid EXL 2650A, EXL 2655, EXL2691 A, each available from The Dow Chemical Company, or Kane

MX series from Kaneka Corporation, such as MX 120, MX 125, MX 130, MX 136, MX 551, or METABLEN SX-006 available from Mitsubishi Rayon.

The curable composition comprises a) an epoxy resin； and b) a hardener component comprising i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and ii) naphthol novolac.

The curable composition may comprise 1 to 90 percent by weight of one or more epoxy resins. All individual values and subranges from 1 to 99 weight percent are included herein and disclosed herein, for example, the weight percent of epoxy resin can be from a lower limit of 12, 17, 20, 30, or 35 weight percent to an upper limit of 55, 70, 86, 90, or 98 weight percent. For example, curable composition may comprise 20 to 98 percent by weight of one or more epoxy resins or in the alternative, curable composition may comprise 30 to 90 percent by weight of one or more epoxy resins. In various embodiments, the epoxy resin is a multifunctional epoxy which has more than two epoxy functionalities. Such epoxy resins include, but are not limited to epoxy resins obtained by glycidifying the condensation product of a phenol or a naphthol with an aldehyde, such as naphthol novolac epoxies, epoxy resins obtained by glycidifying the co-condensation product of naphthol, phenol, and formaldehyde, bisphenol-A novolac epoxies, bisphenol-F novolac epoxies and combinations thereof.

The present invention curable composition includes at least one epoxy resin. The epoxy resin may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic and may be substituted. The epoxy resin may also be monomeric or polymeric.

The epoxy resins, used in embodiments disclosed herein for component (a) of the present invention, may vary and include conventional and commercially available epoxy resins, which may be used alone or in combinations of two or more. In choosing epoxy resins for compositions disclosed herein, consideration should not only be given to properties of the final product, but also to viscosity and other properties that may influence the processing of the resin composition.

Examples of epoxy compounds include, but are not limited to epoxies based on reaction products of polyfunctional alcohols, phenols, cycloaliphatic carboxylic acids, aromatic amines, or aminophenols with epichlorohydrin. A few non-limiting embodiments include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, and triglycidyl ethers of para-aminophenols. Other suitable epoxy resins known to the skilled worker include reaction products of epichlorohydrin with o-cresol and, respectively, phenol novolacs. Further epoxy resins include epoxides of divinylbenzene or divinylnaphthalene. It is also possible to use a mixture of two or more epoxy resins.

The epoxy resins useful in the present invention may be selected from commercially available products； for example, D. E.

331, D. E. R. 332, D. E. R. 383, D. E. R. 334, D. E. N. 431, D. E. N. 438, D. E. R. 736, or D. E. R. 732 epoxy resins available from The Dow Chemical Company or Syna 21 cycloaliphatic epoxy resin from Synasia.

The curable composition may comprise 1 to 99 percent by weight of one or more naphthol novolacs. All individual values and subranges from 1 to 99 weight percent are included herein and disclosed herein, for example, the weight percent of naphthol novolac can be from a lower limit of 1, 1.2, 1.5, 12, or 20 weight percent to an upper limit of 45, 50, 54, 60, or 70 weight percent. For example, curable composition may comprise 1 to 60 percent by weight of one or more naphthol novolacs or in the alternative, curable composition may comprise 1 to 50 percent by weight of one or more naphthol novolacs. Such naphthol novolacs include but are not limited to the condensate of substituted and/or unsubstituted naphthols with monoaldehyde, such as the condensate of 1-naphthol (α-naphthol) with formaldehyde, the condensate of 1-naphthol with acetaldehyde, the condensate of 1-naphthol with butyraldehyde, the condensate of 2-naphthol (β-naphthol) with formaldehyde, the condensate of 2-naphthol with acetaldehyde, the condensate of 2-naphthol with butyraldehyde, the condensate of 1-naphthol and phenol with formaldehyde, the condensate of 1-naphthol and phenol with acetaldehyde, the condensate of 1-naphthol and phenol with butyraldehyde, the condensate of 2-naphthol and phenol with formaldehyde, the condensate of 1-naphthol and cresol with formaldehyde, the condensate of 2-naphthol and cresol with formaldehyde, and combinations thereof. In an embodiment, the curable composition comprises one or more condensates of substituted and/or unsubstituted 1-naphthol with monoaldehyde.

The curable composition may comprise 1 to 80 percent by weight of one or more oligomeric compounds comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). All individual values and subranges from 1 to 80 weight percent are included herein and disclosed herein, for example, the weight percent of DOPO compound can be from a lower limit of 1.5, 2, 3, 5, or 10 weight percent to an upper limit of 20, 40, 55, 60, or 70 weight percent. For example, curable composition may comprise 2 to 60 percent by weight of one or more DOPO compound or in the alternative, curable composition may comprise 5 to 40 percent by weight of one or more DOPO compound. In an embodiment, the curable composition has a total weight percent of atomic phosphorus in the range of from 0.01 weight percent to 20 weight percent. All individual values and subranges from 0.01 to 20 weight percent are included herein and disclosed herein, for example, the weight percent of atomic phosphorus can be from a lower limit of 0.01, 0.5, 1.25, 2.65 and 3.0 to an upper limit of 2.65, 7, 11, 16, and 20.

In an embodiment, the DOPO-containing compound is an oligomeric composition comprising a phosphorus-containing compound which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide ('H-DOP'). This reaction product, referred to hereinafter as 'DOP-BN, 'is depicted in Formula I, below.

Formula I

Further information about DOP-BN and its preparation can be found in US Pat. No. 8, 124, 716.

In one or more embodiments, the curable composition can contain a solvent. Solvents can be used to solubilize the epoxy and hardener component or to adjust the viscosity of the final varnish. Examples of solvents that can be used include, but are not limited to methanol, acetone, n-butanol, methyl ethyl ketone (MEK), cyclohexanone, benzene, toluene, xylene, dimethylformamide (DMF), ethyl alcohol (EtOH), propylene glycol methyl ether (PM) , propylene glycol methyl ether acetate (DOWANOL^TM PMA) and mixtures thereof.

The composition can be produced by any suitable process known to those skilled in the art. In an embodiment, solutions of the epoxy component, phosphorus-containing compound, and polymeric anhydride are mixed together. Any other desired component, such as the optional components described above, are then added to the mixture.

Embodiments of the present disclosure provide prepregs that includes a reinforcement component and the curable composition, as discussed herein. The prepreg can be obtained by a process that includes impregnating a matrix component into the reinforcement component. The matrix component surrounds and/or supports the reinforcement component. The disclosed curable compositions can be used for the matrix component. The matrix component and the reinforcement component of the prepreg provide a synergism. This synergism provides that the prepregs and/or products obtained by curing the prepregs have mechanical and/or physical properties that are unattainable with only the individual components. The prepregs can be used to make electrical laminates for printed circuit boards.

The reinforcement component can be a fiber. Examples of fibers include, but are not limited to, glass, aramid, carbon, polyester, polyethylene, quartz, metal, ceramic, biomass, and combinations thereof. The fibers can be coated. An example of a fiber coating includes, but is not limited to, boron.

Examples of glass fibers include, but are not limited to, A-glass fibers, E-glass fibers, C-glass fibers, R-glass fibers, S-glass fibers, T-glass fibers, and combinations thereof. Aramids are organic polymers, examples of which include, but are not limited to,

and combinations thereof. Examples of carbon fibers include, but are not limited to, those fibers formed from polyacrylonitrile, pitch, rayon, cellulose, and combinations thereof. Examples of metal fibers include, but are not limited to, stainless steel, chromium, nickel, platinum, titanium, copper, aluminum, beryllium, tungsten, and combinations thereof. Examples of ceramic fibers include, but are not limited to, those fibers formed from aluminum oxide, silicon dioxide, zirconium dioxide, silicon nitride, silicon carbide, boron carbide, boron nitride, silicon boride, and combinations thereof. Examples of biomass fibers include, but are not limited to, those fibers formed from wood, non-wood, and combinations thereof.

The reinforcement component can be a fabric. The fabric can be formed from the fiber, as discussed herein. Examples of fabrics include, but are not limited to, stitched fabrics, woven fabrics, and combinations thereof. The fabric can be unidirectional, multiaxial, and combinations thereof. The reinforcement component can be a combination of the fiber and the fabric.

The prepreg is obtainable by impregnating the matrix component into the reinforcement component. Impregnating the matrix component into the reinforcement component may be accomplished by a variety of processes. The prepreg can be formed by contacting the reinforcement component and the matrix component via rolling, dipping, spraying, or other such procedures. After the prepreg reinforcement component has been contacted with the prepreg matrix component, the solvent can be removed via volatilization. While and/or after the solvent is volatilized the prepreg matrix component can be cured, e. g. partially cured. This volatilization of the solvent and/or the partial curing can be referred to as B-staging. The B-staged product can be referred to as the prepreg.

For some applications, B-staging can occur via an exposure to a temperature of 60℃ to 250℃； for example B-staging can occur via an exposure to a temperature from 65℃ to 240℃, or 70℃ to 230℃. For some applications, B-staging can occur for a period of time of 1 minute (min) to 60 min； for example B-staging can occur for a period of time from, 2 min to 50 min, or 5 min to 40 min. However, for some applications the B-staging can occur at another temperature and/or another period of time.

One or more of the prepregs may be cured (e. g. more fully cured) to obtain a cured product. The prepregs can be layered and/or formed into a shape before being cured further. For some applications (e. g. when an electrical laminate is being produced) layers of the prepreg can be alternated with layers of a conductive material. An example of the conductive material includes, but is not limited to, copper foil. The prepreg layers can then be exposed to conditions so that the matrix component becomes more fully cured.

One example of a process for obtaining the more fully cured product is pressing. One or more prepregs may be placed into a press where it subjected to a curing force for a predetermined curing time interval to obtain the more fully cured product. The press has a curing temperature in the curing temperature ranges stated above. For one or more embodiments, the press has a curing temperature that is ramped from a lower curing temperature to a higher curing temperature over a ramp time interval.

During the pressing, the one or more prepregs can be subjected to a curing force via the press. The curing force may have a value that is 10 kilopascals (kPa) to 350 kPa； for example the curing force may have a value that is 20 kPa to 300 kPa, or 30 kPa to 275 kPa. The predetermined curing time interval may have a value that is 5 s to 500 s； for example the predetermined curing time interval may have a value that is 25 s to 540 s, or 45 s to 520 s. For other processes for obtaining the cured product other curing temperatures, curing force values, and/or predetermined curing time intervals are possible. Additionally, the process may be repeated to further cure the prepreg and obtain the cured product.

The prepregs can be used to make composites, electrical laminates, and coatings. Printed circuit boards prepared from the electrical laminates can be used for a variety of applications. In an embodiment, the printed circuit boards are used in smartphones and tablets. In various embodiments, the electrical laminates have a copper peel strength in the range of from 4 lb/in to 12 lb/in. In various embodiments, the electrical laminates have a Tg of greater than or equal to 160℃. In various embodiments, the electrical laminates have a UL-94 classification of V-0.

EXAMPLES

The raw materials used are shown below.

KEB-3165, an epoxy bisphenol-A novolac, from Kolon

Styrene maleic anhydride copolymer

EF-60, from Cray Valley

XZ-92741 (DOP-BN), from The Dow Chemical Company

XZ-97103, an oxazolidone-modified epoxy from The Dow Chemical Company

Fortegra^TM 351 toughener from The Dow Chemical Company

XZ-97102, a phosphorous-containing phenolic hardener from the Dow Chemical Company Copper foils from Oak Mitsui

Examples–Part I

Synthesis of Naphthol Novolac

All materials used in synthesizing naphthol novolacs were directly from commercially available source Aldrich except as mentioned otherwise.

To a 500 mL four neck flask equipped with a refluxing condenser, nitrogen inlet and temperature sensor, 72 grams of 1-naphthol (0.5 mol) were added to 200 mL toluene. The mixture was heated to 50℃ to disperse naphthol in the solvent. 13 grams of paraformaldehyde (0.5*0.87 mol) and 1.26 grams of oxalic acid (0.5*0.02 mol) were then added. The mixture was heated carefully to 60℃ and the system temperature automatically rose to 75-80℃ in 10 minutes and then dropped to 65℃. The toluene mixture was heated to reflux and was stirred under N₂ atmosphere overnight. The reaction mixture was allowed to cool to 50℃ and a solid was precipitated from the solution. The upper toluene solution was poured out and 200 mL ethyl acetate was added and stirred for additional 10 minutes. The ethyl acetate solution was washed with water three times and the organic phase was collected and dried over anhydrous sodium sulfate for 2 hours. The solid was filtrated and most of the solvent was removed under vacuum. The residual was dissolved in 20 mL acetone and poured into a plastic container. The acetone was removed by standing overnight in the fume hood and was dried under vacuum at 80℃ overnight to yield the naphthol novolac. ¹H NMR (acetone-d6, 400 MHz): 8.31–6.96 ppm (m, 6H) ； 4.54–4.05 ppm (m, 1.5H)； GPC (THF): M_n:1000 g/mol； M_w: 1500 g/mol； M_z: 2300 g/mol； PDI: 1.50.

NMR spectra were recorded on a Varian Mercury Plus 400 MHz spectrometer. Chemical shifts were reported versus tetramethylsilane.

Processing and testing:

Ingredients

Epoxy XZ92748 (phenol novolac epoxy: 85％ in Propylene Glycol Monomethyl Ether/Methanol), from The Dow Chemical Company；

Epoxy DER^TM ('DER') 383 (100％ Diglycidyl ether of bisphenol A epoxy), from The Dow Chemical Company；

Naphthol novolac (50％ in acetone), synthesized compound from the above process；

DOP-BN: XZ92741 (57％ in Propylene Glycol Monomethyl Ether), from The Dow Chemical Company；

2-methylimidazole: curing catalyst (10％ in Propylene Glycol Monomethyl Ether), from Sinapharm Chemical and Reagent Company；

XZ92535 (Phenol novolac: 50％ in Propylene Glycol Monomethyl Ether), from The Dow Chemical Company.

The above ingredients were mixed and shaken to form a uniform solution on a shaker. Laminates were prepared by the procedure shown in Table 1, below. The testing results were shown in Table 2.

Table 1-Prepreg lamination procedure

Comparative example A: Phenol novolac epoxy+phenol novolac+DOP-BN

Inventive example 1: Phenol novolac epoxy+naphthol novolac+DOP-BN

Comparative example B: DEGBA+phenol novolac+DOP-BN

Inventive example 2: DEGBA+naphthol novolac+DOP-BN

Results in Table 2, below, show that the Inventive Example 1 has:

1) A shorter burning time (19.9 s) in UL94 testing, compared with Comparative Example A (26.7 s) ；

2) A T_g, which was about 31℃ higher than the T_g of Comparative Example A, according to DSC data, and about 26℃ higher than the T_g of Comparative Example A according to DMA data. and

3) A lower moisture uptake value, which decreased by 0.1％ compared to Comparative Example A.

It is also seen from Table 2 that the Inventive Example 2 has:

1) A shorter burning time in UL94 testing and a UL94 rating of V0, while the Comparative Example 2 had a UL94 rating of V1；

2) A higher T_g , which was about 27℃ higher than the T_g of Comparative Example B according to DSC data, and about 29℃ higher than the T_g of Comparative Example B, according to DMA data； and

3) A lower moisture uptake value, which decreased by 0.2％ compared to Comparative Example B.

T_d values of all the inventive examples tested by TGA are all higher than 350℃, which meet the requirements of epoxy laminate application.

Table 2-Evaluation results of the inventive and comparative examples

Examples–Part II

Synthesis of naphthol novolac

All materials used in synthesizing naphthol novolacs were directly from commercially available source Sinopharm Co. (Shanghai, China) except mentioned otherwise.

To a 1000 mL three neck round-bottom-flask equipped with a refluxing condenser, mechanical stirring and temperature sensor, 72g 1-naphthol (0.5 mol) was added to 200 mL toluene. The mixture was heated to 70℃ to disperse 1-naphthol in the solvent. 13 grams of paraformaldehyde (0.5*0.87 mol) and 1.26 grams of oxalic acid (0.5*0.02 mol) were then added. The reaction mixture was heated carefully to 110℃ and was stirred under a N₂ atomsphere for 72 hours. The reaction mixture was allowed to cool to 50℃ and the products precipitated from the solution. The upper toluene solution was poured out and 200 mL ethyl acetate was added and stirred for additional 10 minutes. The ethyl acetate solution was washed with water once and then with saturated brine twice. The organic phase was collected and dried over anhydrous sodium sulfate for 2 hours. Then the salt was filtrated and most of the solvent was removed under vacuum. Finally, the product was dried in vacuum oven at 100℃ overnight. The yield was 80％. The naphthol monomer content in the final product is 0.4％. ¹H NMR (acetone-d⁶, 400 MHz): 8.31-6.96 ppm (m, 6H) ； 4.54-4.05 ppm (m, 1.5 H)；gel permeation chromatography (GPC) (THF): M_n: 1000 g/mol； M_w: 1600 g/mol； PDI: 1.60. The conditions for GPC are shown in Table 3.

Table 3-Gel Permeation Chromatography (GPC) Conditions

NMR spectra were recorded on a Varian Mercury Plus 400 MHz spectrometer. Chemical shifts were reported vs. tetramethylsilane.

Varnish formulations

Ingredients

Epoxy eCHTP (four functionality epoxy, 74.2％ in methyl ethyl ketone), from The Dow Chemical Company；

Epoxy eDCPD-TP (four functionality epoxy), from The Dow Chemical Company；

Epoxy XZ 97109 (75％ in methyl ethyl ketone), from The Dow Chemical Company；

Epoxy Tactix 742 (three functionality epoxy, 75％ in methyl ethyl ketone), from Huntsman；

HP 4700 (four functionality epoxy), from DIC Corporation；

Naphthol novolac, synthesized compound from the above process；

XZ 92741 (DOP-BN 57％ in Propylene Glycol Monomethyl Ether), from The Dow Chemical Company；

XZ 92535 (phenol novolac resin 50％ in Propylene Glycol Monomethyl Ether), from The Dow Chemical Company；

2-phenylimidazole: curing catalyst (10％ in methyl ethyl ketone), from Sinopharm Chemical and Reagent Company；

2-methylimidazole: curing catalyst (10％ in Propylene Glycol Monomethyl Ether) , from Sinopharm Chemical and Reagent Company；

Silica: Silbond 600EST (amorphous silica filler with amino-silane treatment), from Sibelco Minerals Co., Ltd.

The above ingredients were mixed according to the corresponding formulations and shaken to form a uniform solution in a shaker. The catalyst was then added to the varnish, and gel time of the varnish was tested on a hot plate maintained at 171℃. The gelled material was recovered from the hot plate surface and post-cured in an oven at 200℃ for 2 hours. Then thermal properties of the cured material were measured by DSC and TGA respectively. The results were shown in Table 4.

Table 4-Varnish formulation and thermal properties of the cured epoxy resins

Results in Table 4 show that:

From the comparison between Inventive Example 5 and Comparative Example C, both of which use the same epoxy resin, Tactix 742, Inventive Example 5 has a T_g improvement as high as 30℃ by replacing the phenol novolac hardener with the inventive naphthol novolac hardener. The same improvement was also found when comparing Inventive Example 7 and Comparative Example E.

From the comparison between the Inventive Examples 3-7 and comparative Ex. D (which uses the common multifunctional epoxy resin), the Inventive Example 3-7 have very high T_g, all of which well exceed 220℃.

Properties of the laminates

A laminate based on an inventive composition (Inventive Example 6) and a control BT laminate sample (Comparative Example E) were prepared. The detailed varnish formulation is listed in Table 5. First, the polymer ingredients were mixed to form a uniform 60％ solution in MEK, and then defoamer BYK A530 and wetting agent BYK W996 were added. The above mixture was shaken in a shaker for 1 hour, and then Silbond 600 EST was added along with MEK. The varnish was shaken until the filler was dispersed well. The varnish was then painted on the glass sheets (Hexcel 7628) and partially cured at 171℃ in a ventilated oven for a given time to make prepregs. Finally, 8 prepregs were hot pressed at 220℃ for one hour to make a laminate, and the laminate was post cured at 220℃ for another two hours. Methods used for testing varnishes, prepregs and laminates are listed in Table 6. The properties of the laminates were then tested and detailed results were shown in Table 7.

The glass transition temperature (T_g) of the laminate was also measured by dynamic mechanic thermal analysis (DMTA). The T_g was determined from the maximum in the tangent delta peak. The testing parameters are below:

Frequency: 6.28 rad/s

Initial Temp: 20.0℃

Final Temp: 350.0℃

Ramp Rate ＝ 3.0℃/min

D_k and D_f Measurements

Samples were analyzed at room temperature by an Agilent 4991A Impendence/Material Analyzer equipped with Agilent 16453A test fixture. Calibration was done using an Agilent Teflon standard plaque using D_k/D_f parameters provided by vendor. Thickness of Teflon standard plaque and all samples was measured by micrometer.

Table 5 Varnish formulation for the laminates

Table 6 Performance test of laminates

The results in Table 6 show that Inventive Example 6 has a substantially higher glass transition temperature and lower Z-axis coefficient of thermal expansion compared with the control BT resin, while retaining almost all the other properties such as heat resistance (copper delamination time), dielectrical properties (such as D_k and D_f), as well as good FR performance.

Table 7 shows the test results for laminates based on different formulations comprising eCHTP, NPN and DOP-BN (Inventive Examples 7-10). For all the formulations, the T_g is above 210℃ after 3 hours of curing at 220℃ and can be further improved to above 225℃ after post cure of the laminate at 250℃ for another 2 hours. The phosphorus content can be decreased to as low as 1.15％ (based on the total solid part) to pass the UL94 V-0 testing.

Table 7 Performance test of laminates

The inventive composition was also tested in a treater run (Inventive example 11). The formulation is as shown in Table 8, and the properties of laminates prepared by treater run are shown in Table 9. The results indicate the laminates prepared with the inventive composition has high T_g and T_d, low CTE, low moisture uptake and excellent resistance to solder drip.

Table 8 Formulation for treater run (Inventive Example 11)

Table 9: Properties of the laminates prepared from the treater run (Inventive Example 11)

Claims

A curable composition comprising:

a) an epoxy resin； and

b) a hardener component comprising

i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and

ii) naphthol novolac.
A curable composition in accordance with claim 1 further comprising a filler selected from the group consisting of natural silica, fused silica, alumina, hydrated alumina, and combinations thereof.
A curable composition in accordance with any one of claims 1 or 2 wherein the epoxy resin is selected from the group consisting of phenol novolac epoxy, diglycidyl ether of bisphenol A and combinations thereof.
A curable composition in accordance with any one of the preceding claims wherein the naphthol novolac comprises one or more condensates of substituted and/or unsubstituted 1-naphthol with monoaldehyde.
A curable composition in accordance with any one of the preceding claims wherein the phosphorus-containing compound is DOP-BN.
A curable composition in accordance with any one of the preceding claims further comprising a catalyst.
A curable composition in accordance with any one of the preceding claims wherein the epoxy component is present in an amount in the range of from 1 weight percent to 90 weight percent, the phosphorus-containing compound is present in an amount in the range of from 2 weight percent to 60 weight percent, and the napthol novolac is present in an amount in the range of 1 weight percent to 60 weight percent, based on the total weight of the formulation.
A curable composition in accordance with any one of the preceding claims having a total weight percent of atomic phosphorus in the range of from 0.01 weight percent to 20 weight percent.
A curable composition in accordance with claim 2 wherein the filler is present in an amount in the range of from 10 weight percent to 80 weight percent.
A curable composition in accordance with claim 6 wherein the catalyst is present in an amount in the range of from 0.01 weight percent to 20 weight percent.
A process for preparing the curable composition of any one of the preceding claims comprising admixing a) an epoxy resin； and b) a hardener component comprising i) an oligomeric compound comprising a phosphorus composition which is the reaction product of an etherified resole with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and ii) naphthol novolac to form the curable composition.
A prepreg prepared from the curable composition of any one of claims 1-10.
An electrical laminate prepared from the curable composition of any one of claims 1-10.
An electrical laminate in accordance with claim 13 wherein the electrical laminate has a T_g greater than or equal to 160℃ and has a UL-94 classification of V-0.
A printed circuit board prepared from the electrical laminate of claim 13.