Halogen-free flame retardant type resin composition

Abstract

The present invention relates to a halogen-free flame-retardant resin composition, based on the weight parts of organic solids, comprising (A) from 1 to 10 parts by weight of bismaleimide resin, (B) from 30 to 60 parts by weight of benzoxazine resin, (C) from 10 to 40 parts by weight of polyepoxy compound, (D) from 5 to 25 parts by weight of phosphorous-containing flame retardant, and (E) from 1 to 25 parts by weight of curing agent, which is amine curing agent and/or phenolic resin curing agent. The present invention further provides prepregs, laminates, laminates for printed circuits prepared from said resin composition.

Claims

1. A halogen-free flame-retardant resin composition, based on the weight parts of organic solids, comprising (A) from 1 to 10 parts by weight of bismaleimide resin, (B) from 30 to 60 parts by weight of benzoxazine resin, (C) from 10 to 40 parts by weight of polyepoxy compound, (D) from 5 to 25 parts by weight of phosphorous-containing flame retardant, and (E) from 1 to 25 parts by weight of curing agent, which is amine curing agent and/or phenolic resin curing agent; wherein the bismaleimide resin is obtained by polymerizing the following bismaleimide monomer, ##STR00013##

2. The composition according to claim 1, characterized in that the benzoxazine resin is any one selected from the group consisting of bisphenol-A benzoxazine resin, bisphenol-F benzoxazine resin, phenolphthalein benzoxazine resin, MDA benzoxazine resin, and a combination of at least two selected therefrom.

3. The composition according to claim 1, characterized in that the polyepoxy compound is any one selected from the group consisting of bisphenol-A epoxy resin, bisphenol-F epoxy resin, phenol novolac epoxy resin, o-cresol formaldehyde epoxy resin, bisphenol-A novolac epoxy resin, epoxy resin having biphenyl structure, epoxy resin having aralkyl structure, dicyclopentadiene epoxy resin, halogen-free epoxy resin having oxazolidinone ring, epoxidised polybutadiene, and a combination of at least two selected therefrom.

4. The composition according to claim 1, characterized in that the phosphorous-containing flame retardant is selected from the group consisting of resorcinol-bi(diphenyl phosphate), bisphenol-A bi(diphenyl phosphate), resorcinol-bi(2,6-xylyl phosphate), dimethyl methylphosphate, phosphazene compound, and a combination of at least two selected therefrom.

5. The composition according to claim 1, characterized in that the phenolic resin curing agent is any one selected from the group consisting of phenolic novolac resin, bisphenol-A novolac resin, nitrogen-containing novolac resin, biphenyl novolac resin, aralkyl novolac resin, alkyl novolac phosphorous-containing novolac resin, and a combination of at least two selected therefrom; the amine curing agent is selected from the group consisting of dicyandiamide curing agent and aromatic amine curing agent, wherein the aromatic amine curing agent is selected from the group consisting of diamino diphenyl ether, diamino diphenyl sulfone, diamino diphenyl methane, m-xylylenediamine, benzidine, and a combination of at least two selected therefrom.

6. The composition according to claim 1, characterized in that the bismaleimide resin in the halogen-free flame-retardant resin composition is in an amount of from 3 to 7 parts by weight.

7. The composition according to claim 1, characterized in that the composition further comprises from 0.1 to 1 part by weight of (F) a curing accelerator.

8. The composition according to claim 7, characterized in that the curing accelerator is an imidazole compound, wherein the imidazole compound is any one selected from 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole or 2-phenylimidazole, 2-undecylimidazole, and a combination of at least two selected therefrom.

9. The composition according to claim 1, characterized in that the composition further comprises from 5 to 60 parts by weight of (G) a filler.

10. The composition according to claim 9, characterized in that the filler is selected from the group consisting of inorganic filler or/and organic filler.

11. The composition according to claim 10, characterized in that the inorganic filler is any one selected from the group consisting of aluminium hydroxide, silica, talcum powder, boehmite, zeolite, wollastonite, magnesia, calcium silicate, calcium carbonate, clay, mica, and a combination of at least two selected therefrom; the organic filler is any one selected from the group consisting of melamine, melamine cyanurate, and a combination of at least two selected therefrom.

12. The composition according to claim 1, characterized in that based on the weight of organic solids, the benzoxazine resin is in an amount of more than 50% of the total weight of the resin in the halogen-free flame-retardant resin composition.

13. The composition according to claim 1, characterized in that the benzoxazine resin in the halogen-free flame-retardant resin composition is in an amount of from 40 to 60 parts by weight.

14. The composition according to claim 1, characterized in that the polyepoxy compound in the halogen-free flame-retardant resin composition is in an amount of from 10 to 25 parts by weight.

15. The composition according to claim 1, characterized in that the phosphorous-containing flame retardant in the halogen-free flame-retardant resin composition is in an amount of from 8 to 18 parts by weight.

16. A prepreg, characterized in that the prepreg comprises the halogen-free flame-retardant resin composition according to claim 1.

17. The prepreg according to claim 16, characterized in that the prepreg comprises fiber or fabric and the halogen-free flame-retardant resin composition attached thereon after impregnating and drying treatments.

18. A laminate, characterized in that the laminate comprises several superimposed prepregs according to claim 16.

19. The laminate according to claim 18, characterized in that each prepreg comprises fiber or fabric and the halogen-free flame-retardant resin composition attached thereon after impregnating and drying treatments.

20. A laminate for printed circuit, characterized in that the laminate for printed circuit comprises several superimposed prepregs according to claim 16, and metal foils placed on one or both sides of the superimposed prepregs.

Description

EMBODIMENTS

(1) In order to better explain the present invention and understand the technical solution of the present invention, the typical but non-limiting examples of the present invention are stated as follows.

(2) The parts represents parts by weight, and the % represents weight % in the Examples and Comparison Examples, unless specially defined.

(3) The formulae of the halogen-free flame retardant resin compositions provided in Examples 1-8 are shown in Table 1.

(4) TABLE-US-00001 TABLE 1 Formulae of the halogen-free flame retardant resin compositions provided in Examples 1-8 Examples (parts by weight) Component* 1 2 3 4 5 6 7 8 A-1 5 1 5 10 5 5 10 10 A-2 B-1 20 20 20 20 60 20 20 B-2 30 30 30 30 30 30 30 C-1 10 10 10 10 10 10 5 20 C-2 15 15 15 15 15 15 5 20 D 15 15 15 15 15 15 15 15 E-1 15 5 5 5 5 5 5 5 E-2 1.5 1.5 1.5 1.5 1.5 1.5 1.5 F 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 G-1 20 20 20 20 20 20 20 20 G-2 20 20 20 20 20 20 20 20

(5) The Component* in Table 1 is explained as follows.

(6) A refers to bismaleimide resin.

(7) A-1 refers to bismaleimide resin having a monomer of 1,6-bismaleimido hexane having the following specific structure

(8) ##STR00011##

(9) B refers to benzoxazine resin.

(10) B-1 refers to a product purchased from Huntsman Advanced Materials and having a model No. LZ 8280.

(11) B-2 refers to a product purchased from Sichuan EM Technology Co., Ltd and having a model No. D125.

(12) C refers to halogen-free epoxy resin.

(13) C-1 refers to a product having a model of HP-7200HHH and purchased from Japan DIC.

(14) C-2 refers to a product having a model of KF8100 and purchased from Korea KOLON.

(15) D refers to a phosphorous-containing flame retardant having a model of SPB-100 and purchased from Japan Otsuka Chemical Co., Ltd.

(16) E refers to curing agent.

(17) E-1 refers to a product having a model of EPONOL 6635M65 and purchased from Korea Momentive,

(18) E-2 refers to a product having a model of DICY and purchased from Ningxia Darong Chemical.

(19) F refers to a curing accelerator, which is 2-phenylimidazole purchased from Shikoku Chemicals Corporation.

(20) G refers to inorganic filler.

(21) G-1 refers to aluminium hydroxide having a purity of more than 99%.

(22) G-2 refers to silicon dioxide having a purity of more than 99%.

(23) The formulae of the halogen-free flame retardant resin compositions provided in Comparison Examples 1-8 are shown in Table 2.

(24) TABLE-US-00002 TABLE 2 Formulae of the halogen-free flame retardant resin compositions provided in Comparison Examples 1-8 Comparison Examples (parts by weight) Component* 1 2 3 4 5 6 7 8 A-1 3 20 5 5 10 10 A-2 10 B-1 20 20 20 20 10 50 20 20 B-2 30 30 30 30 10 50 30 30 C-1 10 10 10 10 10 3 30 C-2 15 15 15 15 15 3 30 D 15 15 15 15 15 15 15 15 E-1 15 5 5 5 5 5 5 5 E-2 1.5 1.5 1.5 1.5 1.5 1.5 1.5 F 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 G-1 20 20 20 20 20 20 20 20 G-2 20 20 20 20 20 20 20 20

(25) In Table 2, the Component* has the same explanation as those in Table 1.

(26) In addition, A-2 in Table 2 refers to bismaleimide resin of trimethyl hexamethylene bismaleimide having the following specific structure

(27) ##STR00012##
Performance Testing

(28) The halogen-free flame retardant resin compositions provided in Examples 1-8 and Comparison Examples 1-8 were used for preparing laminates for printed circuits according to the following method, and performance testing was performed for the prepared laminates.

(29) The method for preparing laminates for printed circuits comprises

(30) {circle around (1)} bonding one or more prepregs together by heating and pressing to prepare laminates;

(31) {circle around (2)} bonding metal foils on one or both sides of laminates prepared in step {circle around (1)};

(32) {circle around (3)} laminating in a laminator.

(33) In step {circle around (2)}, 8 sheets of prepregs and 2 sheets of metal foils in an amount of 1 ounce (having a thickness of 35 m) were superimposed together.

(34) In step {circle around (3)}, the operation conditions for lamination are stated as follows. When the material temperature ranged from 80 to 140 C., the temperature rising rate was controlled to be 1.5-2.5 C./min; when the material temperature of the outer layer ranged from 80 to 100 C., a full pressure of about 350 psi was applied. During the curing, the material temperature was controlled to be 195 C. and maintained for more than 60 min.

(35) The items and specific method for the performance testing are stated as follows.

(36) (a) Glass transition temperature: tested by the DSC method under IPC-TM-650 2.4.25 in accordance with Differential scanning calorimetry.

(37) (b) Peeling strength: the peeling strength of the metal cover coat was tested under the test conditions after heat press in accordance with the method of IPC-TM-650 2.4.8.

(38) (c) Inflaming retarding: tested in accordance with UL94.

(39) (d) Dip-soldering resistance: a sample (a laminate for printed circuit of 100100 mm) which was maintained for 2 h in a pressure cooking processing device at 121 C. and 105 KPa was dipped for 20 seconds in a solder bath heated to 260 C., to visually observe (h1) whether there was delamination, and (h2) whether there were white spots or wrinkles, and record. The symbols represents unchanged; represents that there are white spots; X represents delamination.
(e) Water absorption: tested according to IPC-TM-650 2.6.2.1
(f) Dielectric dissipation factor: testing the dielectric dissipation factor at 1 GHz by the resonance method of strip lines according to IPC-TM-650 2.5.5.5;
(g) Bending strength: tested by the method in accordance with IPC-TM-650 2.4.4, i.e. testing by apply load at room temperature onto the samples having predetermined size and shape.
(h) Punching: a substrate having a thickness of 1.60 mm was placed on a die having a certain patterning for punching, to visually observe (h1) whether there were no white circles on the side of holes, (h2) whether there were white circles on the side of holes, and (h3) there were crackings on the side of holes, respectively represented by the symbols , and X.
(i) Migration resistance: a substrate having a size of 100100 mm was placed in an oven having a temperature of 200 C. for 4 hours, to visually observe the exudation of substances between laminates, wherein (h1) refers to no exudation; (h2) refers to a little exudation; and (h3) refers to much exudation, respectively represented by the symbols , and X.
(j) Anti-CAF: tested according to the standard method of JPCA-ES-04.
(k) Drop hammer impact area: a substrate having a thickness of 1.60 mm and a size of 100100 mm was horizontally placed on a rack in which there is a circular channel having a diameter of 8 cm and running through the vertical cross-section of the rack; a cross face hammer having a weight of 1 kg and a hammer diameter of 10 mm was placed at a height of 1 m, aligned to the circular cross-section of the rack, vertically free-fall to the plate; calculating the area of white stripes appeared on the plate.
(l) Halogen content: tested according to the testing method of halogen-free copper clad plate in JPCA-ES-01-2003, and testing the halogen content of copper clad laminate by the Oxygen flask combustion method and ion chromatography.

(40) The performance test results of the laminates for printed circuits prepared from the halogen-free flame retardant resin compositions according to Examples 1-8 are shown in Table 3 below.

(41) TABLE-US-00003 TABLE 3 Performance test results of the laminates for printed circuits prepared from the resin compositions according to Examples 1-8 Examples Items 1 2 3 4 5 6 7 8 Glass transition temperature 169 172 174 175 161 178 176 158 (Tg, C.) Peeling strength (N/mm) 1.36 1.42 1.38 1.31 1.46 1.35 1.26 1.54 Inflaming retarding (1.60 mm) V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-1 Inflaming retarding (0.80 mm) V-0 V-0 V-0 V-0 V-1 V-0 V-1 V-1 Dip-soldering resistance (Delamination) Dip-soldering resistance (white spot) Water absorption (%) 0.09 0.10 0.10 0.10 0.11 0.08 0.10 0.11 Dielectric dissipation factor 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 (1 GHZ) Bending strength (N/mm.sup.2) 510 525 505 495 480 550 485 450 Punching Migration resistance Anti-CAF(hr) >1000 >1000 >1000 >1000 >800 >1000 >800 >500 Drop hammer impact area 250 230 220 180 210 265 205 195 (mm.sup.2) Halogen content (%) 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

(42) The performance test results of the laminates for printed circuits prepared from the halogen-free flame retardant resin compositions according to Comparison Examples 1-8 are shown in Table 4 below.

(43) TABLE-US-00004 TABLE 4 Performance test results of the laminates for printed circuits prepared from the resin compositions according to Comparison Examples 1-8 Comparison Examples Items 1 2 3 4 5 6 7 8 Glass transition temperature 165 154 171 167 163 182 177 155 (Tg, C.) Peeling strength (N/mm) 1.30 1.08 1.32 1.25 1.58 1.34 1.20 1.60 Inflaming retarding (1.60 mm) V-0 V-0 V-0 V-1 V-1 V-0 V-0 V-1 Inflaming retarding (0.80 mm) V-1 V-1 V-1 V-1 V-1 V-0 V-0 V-1 Dip-soldering resistance (Delamination) Dip-soldering resistance (white spot) Water absorption (%) 0.09 0.08 0.09 0.10 0.11 0.08 0.10 0.12 Dielectric dissipation factor 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 (1 GHZ) Bending strength (N/mm.sup.2) 510 460 480 400 475 580 510 440 Punching Migration resistance Anti-CAF (hr) >1000 >500 >1000 >500 >800 >1000 >800 >400 Drop hammer impact area 280 270 160 140 200 285 225 180 (mm.sup.2) Halogen content (%) 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

(44) In Table 4, the halogen-free resin composition provided in Comparison Example 4 is much difficult to dissolve; the composition glue solution has a high viscosity, and the gluing yield is low. During actual operations, the decrease of the environmental temperature readily induces the separation of bismaleimide resin, which greatly affects the production efficiency and causes certain quality problems. The halogen-free resin compositions provided in Examples 1-8 can better adapt existing equipments and process control conditions, and can be continuously and stably produced without any additional equipment. In addition, it has a high gluing yield and a controllable quality.

(45) According to the performance testing results in Table 4, it can be seen that the composition containing no bismaleimide (see Comparison Example 1) has a bigger drop hammer area and a worse toughness. The composition having no polyepoxy (see Comparison Example 2) has a very low peeling strength, a notably decreased bending strength and a worse reliability (anti-CAF). Although the composition having an excessive bismaleimide (see Comparison Example 3) has a better toughness performance, a decreased peeling strength and a reduced bending strength affect the comprehensive performance of the composition. Bismaleimide resin having more branched chains (see Comparison Example 4) has problems of being difficult to dissolve and having a worse technological efficiency. The amount of benzoxazine resin has a notable effect on the composition. If the amount thereof is below 30 parts by weight (see Comparison Example 5), retardant inadequacy will take place; if the amount goes beyond 60 parts by weight (see Comparison Example 6), the punching property thereof will be decreased though a higher Tg is readily obtained. If the polyepoxy resin amount is reduced below 10 parts by weight (see Comparison Example 7), the peeling strength thereof will be sharply decreased to affect the application thereof. If polyepoxy is in an excessive amount (see Comparison Example 8), the glass transition temperature, inflaming retarding and reliability all will be decreased.

(46) According to the halogen-free resin flame-retardant compositions provided in Examples 1-8 and Comparison Examples 1-8 and the corresponding performance testing results, it can be seen that the efficient combinations of various types, classes and contents of the resin composition components of the present invention, especially the selection of epoxy resins, makes the resin compositions ensure a higher peeling strength of the resin compositions provided therein, while increasing the process operability of the compositions. The selection of bismaleimide resin makes the resin composition provided therein maintain excellent properties, such as a higher glass transition temperature (Tg) and a high reliability, while obtaining a higher toughness.

(47) According to the results above, it can be seen that the laminates for printed circuits prepared from the halogen-free flame retardant resin composition provided in the present invention greatly decrease the fragility of the benzoxazine system and increase the toughness of the laminates while maintaining high glass transition temperature, high reliability, inflaming retarding, dip-soldering resistance, chemical resistance, low hydroscopicity, lower dielectric dissipation factor. In addition, the halogen content can achieve the V-0 standard in the flame retardancy test UL94 within the scope of halogen-free standard of JPCA. The halogen content of the present invention is less than 0.09 wt. %, so as to achieve the effect of environmental protection.

(48) The formulae of the halogen-free flame retardant resin compositions provided in Examples 9-12 and Comparison Examples 9-12 are shown in Table 5.

(49) TABLE-US-00005 TABLE 5 Formulae of the halogen-free flame retardant resin compositions provided in Examples 9-12 and Comparison Examples 9-12 Comparison Examples Examples (parts by weight) (parts by weight) Components* 9 10 11 12 9 10 11 12 A-1 5 5 5 5 5 5 5 5 B-1 15 15 30 30 10 10 50 50 B-2 15 15 30 30 10 10 50 50 C-1 20 20 20 20 20 20 20 20 D 25 25 5 5 5 25 25 25 E-2 1.5 1.5 1 1 1.5 1.5 1 1 F 0.15 0.15 0.15 0.15 0 0.15 0 0.15 G-1 20 0 0 0 0 50 0 0 G-2 0 0 20 0 0 0 0 50

(50) In Table 5, the Component* has the same explanation as those in Table 1.

(51) The performance test results of the laminates for printed circuits prepared from the halogen-free flame retardant resin compositions according to Examples 9-12 and Comparison Examples 9-12 are shown in Table 6 below.

(52) TABLE-US-00006 TABLE 6 Performance test results of the laminates for printed circuits prepared from the resin compositions according to Examples 9-12 and Comparison Examples 9-12 Examples Comparison Examples Items 9 10 11 12 9 10 11 12 Glass transition 161 163 174 172 147 152 180 188 temperature (Tg, C.) Peeling strength (N/mm) 1.43 1.47 1.40 1.54 1.54 1.42 1.38 1.26 Inflaming retarding V-0 V-0 V-0 V-0 V-1 V-0 V-0 V-0 (1.60 mm) Inflaming retarding V-0 V-0 V-0 V-0 V-1 V-1 V-0 V-0 (0.80 mm) Dip-soldering resistance (Delamination) Dip-soldering resistance (white spot) Water absorption (%) 0.10 0.10 0.09 0.10 0.14 0.12 0.08 0.07 Dielectric dissipation 0.005 0.005 0.005 0.005 0.006 0.006 0.004 0.004 factor (1 GHZ) Bending strength 530 515 545 520 475 485 620 650 (N/mm.sup.2) Punching X Migration resistance Anti-CAF(hr) >1000 >1000 >1000 >1000 >600 >800 >1000 >1000 Drop hammer impact 256 285 240 280 285 250 390 345 area (mm.sup.2) Halogen content (%) 0.04 0.04 0.03 0.03 0.04 0.04 0.03 0.02

(53) According to the performance test results in Table 6, it can be seen that, when the benzoxazine resin content ranges from 30 to 60 parts by weight, the composition can have a glass transition temperature (Tg) of more than 160 C., a inflaming retarding of UL94V-0, a water absorption of about 0.10% and a better toughness. When the benzoxazine resin content is lower than 30 parts by weight, it has a notably decreased glass transition temperature (Tg), an increased water absorption, and a decreased Anti-CAF, which all seriously affected the overall performance of the composition, though the peeling strength is improved. When the benzoxazine content is higher than 60 parts by weight, the composition shows a deteriorated toughness and a decreased processability, so that it cannot meet the requirements. Fair use of fillers can decrease the water absorption of the composition, increase the reliability thereof, and increase the comprehensive performance of the resin composition.

(54) It should be noticed and understood that, without departing from the spirit and scope of the present invention claimed in the claims, modifications and changes can be made to the present invention detailedly stated above. Thus the scope of the claimed technical solution is not limited by any specific exemplary teachings provided therein.

(55) The applicant declares that, the present invention detailedly discloses the process of the present invention by the aforesaid examples, but the present invention is not limited by the detailed process, i.e. it does not mean that the present invention cannot be fulfilled unless the aforesaid detailed process is used. Those skilled in the art shall know that, any amendment, equivalent change to the product materials of the present invention, addition of auxiliary ingredients, and selection of any specific modes all fall within the protection scope and disclosure scope of the present invention.