High-CTI and halogen-free epoxy resin composition for copper-clad plates and use thereof

Abstract

A high-CTI and halogen-free epoxy resin composition for copper-clad plates and uses thereof is provided. The formula of the high-CTI and halogen-free epoxy resin composition for copper-clad plates comprises 100140 parts of halogen-free phosphorous epoxy resin, 1035 parts of dicyclopentadiene phenolic epoxy resin, 3260 parts of benzoxazine, 15 parts of phenolic resin, 0.050.5 parts of accelerants; and 2570 parts of fillers, by weight. The copper-clad plates, prepared according to embodiments of the present invention, can reach the requirements of high CTI (CTI500V), high heat resistance (Tg150 C., PCT, 2 h>6 min) and the level of flame retardance of UL-94 V0, and they are widely used in the electronic materials of electric machines, electric appliances, white goods and so on.

Claims

1. A high-CTI and halogen-free epoxy resin composition for copper-clad plates, comprising: 100 to 140 parts by weight of halogen-free phosphorous epoxy resin; 10 to 35 parts by weight of dicyclopentadiene phenolic epoxy resin; 1 to 5 parts by weight of phenolic resin; 32 to 60 parts by weight of benzoxazine; 0.05 to 0.5 parts by weight of curing accelerant; and 25 to 70 parts by weight of filler.

2. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 1, wherein the halogen-free phosphorous epoxy resin is synthesized by: (1) weighting a straight-chain epoxy resin and a reactive phosphorous compound such that, when combined for reaction, the straight-chain epoxy resin accounts for 5575% by weight and the reactive phosphorous compound accounts for 2545% by weight, of a combined weight of the straight chain epoxy resin and the reactive phosphorous compound; (2) preparing the halogen-free phosphorous epoxy resin, by: adding the weighted straight-chain epoxy resin and the weighted reactive phosphorous compound into a reactor to dissolve them at an increased temperature; adding a reaction accelerant at 110130 C.; raising the temperature to a reaction temperature of 170190 C.; maintaining the reaction temperature for 24 hours; decreasing the temperature; and adding solvents for dissolution, thus to obtain the halogen-free phosphorous epoxy resin with a solid content of 6575%, a phosphorus content of 2.54.5% and an epoxy equivalent weight of 5001000 g/eq.

3. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 2, wherein the straight-chain epoxy resin is one or at least two selected from the group consisting of BPA epoxy resin, BPF epoxy resin and bisphenol S linear epoxy resin; and the reactive phosphorous compounds are one or two of DOPO-HQ and DOPO-NQ.

4. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 2, wherein the benzoxazine is one or more selected from the group consisting of BPA benzoxazine, BPF benzoxazine and DDM benzoxazine.

5. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 2, wherein the phenolic resin is one or more selected from the group consisting of linear phenolic resin, o-cresol formaldehyde resin and BPA phenolic resin.

6. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 2, wherein the accelerants are one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.

7. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 2, wherein a mass ratio of the reaction accelerant and the reactive phosphorous compound is 0.050.15:100; and wherein the reaction accelerant is triphenylphosphine, triphenyl phosphate, quaternary ammonium salts or quaternary phosphonium salts.

8. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 7, wherein the straight-chain epoxy resin is one or at least two selected from the group consisting of BPA epoxy resin, BPF epoxy resin and bisphenol S linear epoxy resin; and the reactive phosphorous compounds are one or two of DOPO-HQ and DOPO-NQ.

9. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 7, wherein the benzoxazine is one or more selected from the group consisting of BPA benzoxazine, BPF benzoxazine and DDM benzoxazine.

10. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 7, wherein the phenolic resin is one or more selected from the group consisting of linear phenolic resin, o-cresol formaldehyde resin and BPA phenolic resin.

11. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 7, wherein the accelerants are one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.

12. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 1, wherein the benzoxazine is one or more selected from the group consisting of BPA benzoxazine, BPF benzoxazine and DDM benzoxazine.

13. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 1, wherein the phenolic resin is one or more selected from the group consisting of linear phenolic resin, o-cresol formaldehyde resin and BPA phenolic resin.

14. The high-CTI and halogen-free epoxy resin composition for copper-clad plates according to claim 1, wherein the accelerants are one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.

15. A method for preparing laminated boards of printed circuits, comprising steps of: preparing the high-CTI and halogen-free epoxy resin composition for copper-clad plates of claim 1; and applying the composition to at least one substrate to prepare laminated boards of printed circuits.

16. The method according to claim 15, further comprising mixing the epoxy resin composition with organic solvent to obtain a solvent-based composition with a solid content of 5070%; and wherein said applying comprises: immersing a glass fibre fabric substrate in the solvent-based composition; drying the immersed glass fibre fabric substrate to form a prepreg; optionally stacking more than one prepreg; applying copper foil to at least one surface of the prepreg or the prepreg stack; and pressurizing and heating the resulting laminated structure at a curing temperature of 50250 C.

17. The method according to claim 16, wherein the organic solvent is one or more selected from the group consisting of butanone, propylene glycol monomethyl ether, cyclohexanone and propylene glycol methyl ether acetate.

Description

DETAILED DESCRIPTION

(1) Embodiments of the invention provides a high-CTI and halogen-free epoxy resin composition for copper-clad plates, which has a formula comprising 100140 parts of halogen-free phosphorous epoxy resin, 1035 parts of dicyclopentadiene phenolic epoxy resin, 3260 parts of benzoxazine, 15 parts of phenolic resin, 0.050.5 parts of accelerants and 2570 parts of fillers, by weight.

(2) The halogen-free phosphorous epoxy resin is prepared by the reaction of the straight-chain epoxy resin and the reactive phosphorous compounds, and the obtained halogen-free phosphorous epoxy resin has a phosphorus content of 2.54.5% and an epoxy equivalent weight of 5001000 g/eq.

(3) Such resin, whose main part is straight-chain phosphorous epoxy resin, has high CTI, good flame retardance, toughness and cohesiveness. The straight-chain epoxy resin may be bisphenol A (BPA) epoxy resin, the bisphenol F (BPF) epoxy resin or the bisphenol S linear epoxy resin. The reactive phosphorous compounds can be one or two selected from DOPO-HQ and DOPO-NQ. The epoxy resin can be synthesized as following steps:

(4) 1) weighting the ingredients according to the formula which comprises 5575% of epoxy resin and 2545% of reactive phosphorous compounds, by weight; wherein the epoxy resin is straight-chain epoxy resin;

(5) 2) preparation of the halogen-free phosphorous epoxy resin, by adding the straight-chain epoxy resin and the reactive phosphorous compounds into the reactor to dissolve them at an increased temperature; adding the accelerants at a temperature in a range from 110 to 130 C., raising the temperature to 170190 C. to keep a reaction for 24 hours; adding solvents to dissolve them after the temperature is decreased, whereby to obtain a solid content of 6575%; wherein, the mass ratio of the accelerants and the reactive phosphorous compounds is 0.050.15:100, preferably is 0.1100, and the accelerants can be one or at least two selected from a group consisting of triphenylphosphine, triphenyl phosphate, quaternary ammonium salts or quaternary phosphonium salts. The solvents in step 2) may be one or at least two selected from a group consisting of butanone, propylene glycol monomethyl ether and cyclohexanone.

(6) The dicyclopentadiene phenolic epoxy resin has a structural formula as follows:

(7) Such kind of resin having a high heat resistance and chemical stability, and good

(8) ##STR00002##
flame retardance, can be used to improve the CTI of the composition.

(9) The benzoxazine is a type of nitrogenous phenolic aldehyde compound synthesized by phenols, aldehydes and amines, and it has an excellent heat resistance and flame retardance. The phosphorus-nitrogen synergistic effect, achieved between the nitrogenous structure and the phosphorous epoxy, can improve the flame retardance of the products. The benzoxazine can be one or at least two selected from a group consisting of the bisphenol A (BPA) benzoxazine, the bisphenol F (BPF) benzoxazine and the diaminodiphenylmethane (DDM) benzoxazine.

(10) The phenolic resin has a high heat resistance and may be one or at least two selected from a group consisting of the linear phenolic resin, the o-cresol formaldehyde resin and the bisphenol A (BPA) phenolic resin.

(11) The accelerants may be one or at least two selected from the imidazole compounds of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.

(12) The fillers may be one or two of aluminium hydroxide and magnesium hydroxide.

(13) The above-mentioned high-CTI and halogen-free epoxy resin composition for copper-clad plates can be used in the preparation of the laminated boards of printed circuits.

(14) In the application, the aforesaid epoxy resin composition is mixed with organic solvents to obtain a composition with a solid content of 5070%, in which the glass fibre fabrics are immersed later, then the immersed glass fibre fabrics are dried into prepregs after heating. Copper foils are placed on one or both surfaces of the prepregs to form laminations of one or more prepregs, which are then heated and pressurized to obtain copper clad laminates at a curing temperature of 50250 C. The organic solvents may be one or at least two selected from a group consisting of butanone, propylene glycol monomethyl ether, cyclohexanone and propylene glycol methyl ether acetate.

(15) Embodiments of the invention will be further explained with reference to preferable examples, without any limitation to the embodiments of the present invention. The designations and ingredients in the examples and comparative examples are listed as below:

(16) Resin 1: the halogen-free phosphorous epoxy resin (A1) of the invention is synthesized as following process: adding the liquid BPA epoxy resin (6070%) and the reactive phosphorous compounds (3040%) into the reactor to dissolve them at an increased temperature; adding the triphenylphosphine (TPP) accelerant at 120 C. and keeping a reaction for 24 hours when the temperature is increase to 170190 C., then adding cyclohexanone to dissolve them after the temperature is decreased, thus to obtain a resin having a solid content of 70%, a phosphorus content of 3.04.0% and an epoxy equivalent weight of 700900 g/eq.

(17) Resin 2: The halogen-free phosphorous epoxy resin (A2) of embodiments of the invention is synthesized as following process: adding the liquid BPF epoxy resin (6070%) and the reactive phosphorous compounds (3545%) into the reactor to dissolve them at an increased temperature, adding the triphenylphosphine (TPP) accelerant at 120 C., raising the temperature to 170190 C., to keep a reaction for 24 hours, then adding cyclohexanone to dissolve them after the temperature is decreased, thus to obtain a resin having a solid content of 70%, a phosphorus content of 3.04.0% and an epoxy equivalent weight of 700900 g/eq.

(18) Resin 3: dicyclopentadiene phenolic epoxy resin 7200HHH, available from the DIC Corporation in Japan.

(19) Resin 4: o-cresol formaldehyde epoxy resin 704, available from the South Asia Corporation.

(20) Resin 5: halogen-free resin produced by ZHUHAI EPOXY BASE Electronic Material Co., LTD, with a trade name of GEBR589K75.

(21) Curing agent 1: diaminodiphenylmethane (DDM) benzoxazine.

(22) Curing agent 2: phenolic resin GERH833K65, available from HongChang ZHUHAI EPOXY BASE Electronic Material Co., LTD

(23) Curing agent 3: dicyandiamide, 10 wt %, dissolved in DMF (dimethyl formamide)

(24) Filler: aluminium hydroxide

(25) Curing accelerant 2PI: 2-phenylimidazole, 1 wt %, dissolved in PM (propylene glycol monomethyl ether)

(26) Glass fibre fabric: Fabric 7628.

Example 1

(27) The ingredients of A1 and 7200HHH of embodiments of the present invention are used as the main resin, mixed with curing agents of DDM benzoxazine and phenolic resin GERH833K65, and a filler of aluminium hydroxide, and the formula composition is listed in detail in Table 1. The butanone (MEK), propylene glycol monomethyl ether (PM) or propylene glycol methyl ether acetate are added to obtain a varnish composition with a solid content of 55%, and the glass fibre fabric 7628 is immersed in the above mentioned varnish resin liquid and dried at a temperature of 170180 C. in the impregnation machine for a few minutes, to obtain a dried prepreg whose melt viscosity is 8001000 Pa.Math.s by adjusting and controlling the drying time. Finally eight layers of prepregs are laminated to each other between two copper foils with a thickness of 35 m, and are pressurized at a pressure of 25 Kg/cm.sup.2 and in a temperature-controlling process as follows:

(28) ##STR00003##

(29) After the hot-pressing, a copper-clad plate with a thickness of 1.6 mm is obtained. The CTI of the composition can be greater than 500V, and the Tg can be higher than 150 C., thus a good heat resistance and a flame retardance level of V0 are achieved. The performances are shown in detail in Table 1.

Example 2

(30) Repeat Example 1, change the content of the ingredients of A1 and 7200HHH, and the CTI of the obtained composition can be greater than 500V, and the Tg can be higher than 150 C., thus a good heat resistance and a flame retardance level of V0 are achieved. The performances are shown in detail in Table 1.

Example 3

(31) The ingredients of A2 and 7200HHH of embodiments of the present invention are used as the main resin, mixed with curing agents of DDM benzoxazine and phenolic resin GERH833K65, and a filler of aluminium hydroxide and the formula of the composition is listed in detail in Table 1. Repeat the process of preparing the plate in Example 1. The CTI of the obtained composition can greater than 500V, and the Tg can be higher than 150 C., thus a good heat resistance and a flame retardance level of V0 are achieved. The performances are shown in detail in Table 1.

Example 4

(32) Repeat Example 3, change the contents of the ingredients of A2 and 7200HHH, and the CTI of the obtained composition can greater than 500V, and the Tg can be higher than 150 C., thus a good heat resistance and a flame retardance level of V0 are achieved. The performances are shown in detail in Table 1.

Comparative Example 1

(33) Repeat Example 4, and replace the ingredient 7200HHH with the ingredient 704, and the obtained composition has a fine heat resistance, but its CTI is less than 400V, and the flame retardance level is only Level V1. The performances are shown in detail in Table 1.

Comparative Example 2

(34) The GEBR589K75 is used as the main resin, mixed with a curing agent of dicyandiamide. Repeat the process of preparing copper-clad plates in Example 1, and the obtained composition has a poor heat resistance (the lasting time is less than 6 min for popcorn in Pressure Cooker Test (PCT), and is less than 60 min in T288). The performances are shown in detail in Table 1.

Comparative Example 3

(35) Repeat Comparative Example 2, and the curing agents are diaminodiphenylmethane (DDM) benzoxazine and phenolic resin GERH833K65 instead. The obtained composition has an unsatisfied CTI and a poor flame retardance, specifically, the CTI is less than 400V, and the level of flame retardance is only level V1. The performances are shown in detail in Table 1.

(36) Descriptions of Measurement

(37) 1) Gelling time of varnish (sec):

(38) 0.3 mL resin varnish is placed on a gel timer, and its gelling time is measured.
2) Glass transition temperature (Tg, C.): It is measured according to 2.4.25 par. of IPC-TM-650.
3) Peel strength (lb/in): It is measured according to 2.4.8 par. of IPC-TM-650.
4) Popcorn in Pressure Cooker Test (PCT) (min): The samples are cooked in the pressure cooker at a pressure of 2 atmosphere and a temperature of 120 C. for 2 hours, then they are immersed in a tin stove at 288 C., and the time for delamination is measured.
5) Comparative Tracking Index (CTI) (V, 50D): It is measured according to GB/T 4207-2003.
6) T288 test (min): The delamination time of the samples is measured by the thermomechanical analysis (TMA) method.
7) Flame retardance It is measured according to vertical burning test of UL94.

Advantageous Effects

(39) It can be found from the performances results of Examples 1-4 and Comparative Examples 1-3 as shown in Table 1 that: in embodiments of the present invention, the high-CTI, halogen-free and phosphorous epoxy resin, mixed with the curing agents of DDM benzoxazine and phenolic resin, can prepare plates having the features of high CTI, high heat resistance, and the like.

(40) Embodiments of the invention should not be limited to those embodiments described above, which are just preferable embodiments, and any changes, modifications, substitution, combination and simplification, without departing from the spirit essence and principle of embodiments of the present invention, are equivalent replacement, and also be included in the scope of embodiments of the present invention.

(41) TABLE-US-00001 TABLE 1 The ingredients of the formulas of resin varnishes and their properties Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Resin 1 the resin 130 120 of embodiments of the present invention A1 Resin 2 the resin 115 100 100 of embodiments of the present invention A2 Resin 3 7200HHH 10 15 20 30 Resin 4 704 30 Resin 5 GEBR589K75 100 100 Curing agent 1 DDM 35 40 45 50 50 50 benzoxazine (PHR) Curing agent 2 3 3 3 3 3 3 GERH833K65 (PHR) Curing agent 3 26 dicyandiamide (PHR) Filler aluminium 40 45 45 45 45 40 40 hydroxide (PHR) Aaccelerant 2- 0.13 0.1 0.1 0.1 0.1 0.1 0.1 PI (PHR) Gelling time 295 290 273 302 297 260 305 of varnish (sec) Glass transition 153 155 153 157 159 154 160 temperature ( C.) Peel strength (lb/in) 10.2 9.8 9.5 9.8 9.2 9.0 8.0 Popcorn in PCT 6 6 6 6 6 1 6 (120 C., 2 h, min) CTI (V, 50 D) 500 500 500 500 400 400 400 T288 (min) 60 60 60 60 60 5 60 Flame retardance 94 V-0 94 V-0 94 V-0 94 V-0 94 V-1 94 V-0 94 V-1

(42) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(43) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.