POLYISOCYANURATE-PREPREGS AND FIBER COMPOSITE COMPONENTS PRODUCED THEREFROM

Abstract

The present invention relates to polyisocyanate compositions comprising two different types of polyisocyanate, their use in the manufacture of prepregs and polyisocyanurate composited made from said prepregs.

Claims

1. A polymerizable composition which is free from isocyanate-reactive groups or has a molar ratio of isocyanate groups of the isocyanate component to isocyanate-reactive groups of at least 2.0:1.0 comprising a) at least one aliphatic polyisocyanate: b) at least one cycloaliphatic polyisocyanate; and c) at least one trimerization catalyst: wherein the concentration of cycloaliphatic polyisocyanates is 25 wt.-% to 75 wt.-% based on the total mass of all polyisocyanates present in the polymerizable composition; and wherein, the concentration of uretdione-forming catalysts in the composition is not more than 10 wt.-% of the total mass of uretdione-forming catalysts and trimerization catalysts present in the polymerizable composition.

2. The polymerizable composition according to claim 1, additionally comprising 10 wt.-% to 50 wt.-% of at least one inert solvent based on the sum of all polyisocyanates, all trimerization catalysts and all solvents.

3. The polymerizable composition according to claim 1, wherein the at least one aliphatic polyisocyanate makes up 10 wt.-% to 80 wt.-% of the total amount of all polyisocyanates present in the polymerizable composition.

4. The polymerizable composition according to claim 1, wherein the at least one aliphatic polyisocyanate and/or the at least one cycloaliphatic polyisocyanate is an oligomeric polyisocyanate containing at least 50 mol-% isocyanurate structures based on the sum total of the oligomeric structures from the group consisting uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione structure present in the respective polyisocyanate.

5. The polymerizable composition of claim 1, wherein a trimerization catalyst according to formula (I) or an adduct thereof is used ##STR00005## wherein R.sup.1 and R.sup.2 are independently of one another selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, branched C5-alkyl, unbranched C5-alkyl, branched C6-alkyl, unbranched C6-alkyl, branched C7-alkyl and unbranched C7-alkyl; A is selected from the group consisting of O, S and NR.sup.3, wherein R.sup.3 is selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl and isobutyl; and B is independently of A selected from the group consisting of OH, SH, NHR.sup.4 and NH.sub.2, wherein R.sup.4 is selected from the group consisting of methyl, ethyl and propyl.

6. The polymerizable composition according to claim 1, additionally comprising an organic or inorganic filler.

7. A method comprising the steps of a) providing a polymerizable composition as defined in claim 1; and b) curing the polymerizable composition at a temperature between 150? C. and 200? C., whereby a semi-finished product is obtained.

8. The method according to claim 7, wherein method step b) is continued until the polymerizable composition reaches a viscosity of 30,000 to 750,000 mPas.

9. The method according to claim 7, wherein method step b) is continued until 2% to 60% of the free isocyanate groups present at the beginning of method step b) are consumed.

10. The method according to claim 7, additionally comprising a method step al) of coating at least one organic or inorganic fiber with the polymerizable composition provided in method step a).

11. The method according to claim 7, additionally comprising a method step c) of curing the semi-finished product, whereby a finished product is obtained.

12. The method according to claim 11, wherein method step c) is commenced 1 day to 30 days after method step b) is finished.

13. (canceled)

14. The method according to claim 11, wherein a finished product is obtained.

15. A copper clad laminate or printed circuit board comprising the product according to claim 11.

Description

EXAMPLES

[0118] The currently prevailing ambient temperature of 25? C. is described as RT in this experimental section.

Determination of the NCO Content by FT-IR:

[0119] IR spectra were recorded on a Spectrum of FT-IR spectrometer from Perkin Elmer, Inc. equipped with an ATR unit. Residual NCO content was monitored by recording the change of isocyanate groups (band at 2270 cm.sup.?1).

Determination of the Tg Value of Cured Resin by DSC:

[0120] The glass transition temperature (Tg) of the prepregs after post curing was determined by differential scanning calorimetry (DSC) on a TA DSC Q20 according to IPC-TM-650 2.4.25.

Determination of Tg Value of CCL by DMA:

[0121] The glass transition temperature Tg of the base laminate material without the cladding was determined using dynamic mechanical analysis according to IPC-TM-650 2.4.24.4.

Determination of Td Value of CCL by DMA:

[0122] The thermal decomposition temperature T.sub.d of base laminate material without the cladding was determined using thermogravimetric analysis according to IPC-TM-650 2.4.24.6 to record the temperature T.sub.d (5%) at which the mass of the sample is 5.0% less than its mass measured at 50? C.

Determination of Dk and Df Values of CCL by SPDR:

[0123] The dielectric constant (Dk) and dissipation factor (Df) of base laminate material without the cladding was determined using split post dielectric resonator (SPDR) at 10G microwave frequency according to IEC 61189-2-721.

Raw Materials:

[0124] Desmodur N 3600 is a hexamethylene diisocyanate (HDI) trimer (NCO functionality >3) with 23.0 wt.-% NCO content, the viscosity is about 1200 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0125] Desmodur N 3900 is a HDI trimer (NCO functionality >3) with 23.5 wt.-% NCO content, the viscosity is about 730 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0126] Desmodur eco N 7300 is a biobased pentamethylene diisocyanate (PDI) trimer (NCO functionality >3) with 21.9 wt.-% NCO content, the viscosity is about 9500 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0127] Desmodur Z4470 is an isophorone diisocyanate (IPDI) trimer (NCO functionality >3) in butyl acetate (BA) or solvent naphtha (SN) with 70 wt.-% solid content, 11.9 wt.-% NCO content, the viscosity is about 1500 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0128] Desmodur IL is a toluene diisocyanate (TDI) trimer (NCO functionality >3) in butyl acetate (BA) or ethyl acetate (EA) with 51 wt.-% solid content, 8.0 wt.-% NCO content, the viscosity is 700-2000 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0129] Desmodur XP 2489 is a HDI isophorone diisocyanate (IPDI) polyisocyanate (NCO functionality >3) with 21.0 wt.-% NCO content, the viscosity is about 22,500 mPas at 23? C. (DIN EN ISO 3219/A.3), from Covestro AG.

[0130] Catalyst: 2-[2-(dimethylamino)ethyl-methylamino] ethanol is purchase from TCI Co. Ltd.

[0131] Solvent: Butyl acetate is purchased with the purity ?99.0% from Sinopharm Chemical Reagent Co., Ltd.

[0132] Silica powder is purchased from Denka Co., jp.

[0133] Type 2116 E-glass fiber woven cloth is purchased from CTM glass fiber Co., Ltd.

General Method of Preparing the Resin Compositions and Prepregs

[0134] 1. The ingredient listed in Table 1 and Table 2 are added to a mixing vessel; [0135] 2. The ingredients are mixed at 2500 rpm for at 60-300 seconds using SpeedMixer DAC 400 FV at room temperature. At this point, the composition is ready for use. [0136] 3. A 2116 woven glass cloth was impregnated into the well-mixed compositions and controlled to have an appropriate thickness [0137] 3. The impregnated glass cloth was baked in an oven at 180-200? C. for 2-15 minutes for removing the solvent and partly curing the resin composition to prepare a prepreg.

[0138] The residual NCO content was monitored by FT-IR.

[0139] The storage-stability was checked by monitoring the residual NCO content after several days using FT-IR. [0140] 4. The prepreg was then pressed at

[0141] 200-220? C., and preferably to give some pressure e.g. 5 bars to give a fiber-composite component.

[0142] The residual NCO content after post curing was monitored by FT-IR

[0143] The Tg and Td of the cured resin in composited was monitored by DSC and TGA.

APPLICATION EXAMPLE

[0144] For making CCL, the resin composition from Example 1, Example 2 and Comparative Example 2 are respectively mixed with 30 wt.-% of silica powder in a certain proportion in butyl acetate, and the solid content of the glue solution was controlled to be 65%. A 2116 glass cloth was impregnated into the above-mentioned glue solution and controlled to have an appropriate thickness, and then based in an oven at 180-200? C. for 2-15 min to prepreg a prepreg. Then 6 sheets of prepreg were stacked together with both sides stacked with copper foils and were cured at a curing temperature of 170-250? C., and a curing pressure of 25-50 bar for 200-300 min to obtain a copper clad laminate.

[0145] The Tg of CCL was monitored by DMA

[0146] The Td of CCL was monitored by TGA

[0147] The DK, Df of CCL was monitored by SPDR

[0148] The performance of the CCL was shown in Table 3.

TABLE-US-00001 TABLE 1 Formulation Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Desmodur N 25 g 35 g 15 g 15 g 3600 Desmodur N 25 g 3900 Desmodur Eco 15 g N7300 Desmodur 35.7 g 21.4 g 50 g 50 g 35.7 g 35.7 g Z4470 Desmodur IL 20 g Desmodur 50 g XP2489 Catalyst 0.39 g 0.39 g 0.39 g 0.39 g 0.39 g 0.39 g 0.39 g Solvent 4.3 g 8.6 g 15 4.3 g Solid content 77% 77% 77% 77% 77% 77% 77% (wt.-%) Residual NCO 94% 98% 94% 93% 47% 98% 89% content % in prepreg Residual NCO 55% 45% 80% 74% 40% 80% 54% content % in prepreg after 10 days Residual NCO 5% 8% 12% 0.2% 9% 8% 5% content % in composite after curing Tg of cured >180 175 >200 >200 >200 175 144 resin in composite by DSC (? C.) Td of cured 345 320 340 340 331 353 295 resin in composite by TGA (? C.)

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Formulation Example 1 Example 2 Example 3 Example 4 Desmodur N 3600 45 g 20 g Desmodur N 3900 Desmodur Z4470 7.1 g 14.3 g Desmodur Eco N7300 40 g Desmodur IL 98 g Catalyst 0.39 g 0.15 g 0.39 g 0.39 g Solvent 12.9 g 6 g 10.7 g Solid content (wt %) 77% 77% 51% 77% Residucal NCO content % 96% 6% 81% 94% in prepreg Residucal NCO content % 25% 2% 18% 38% in prepreg after 10 days Residucal NCO content % 2% 2% 16% 3% in composite after curing Tg of cured resin in composite 128 111 >200 140 by DSC (? C.) Td of cured resin in composite 340 315 360 334 by TGA (? C.)

TABLE-US-00003 TABLE 3 Application Application Comparative Application Example 1 Example2 Example 1 Based on: Example 1 Example 2 Comparative Example 2 Dk by SPDR at 3.87 3.77 The prepregs can't 10 GHZ be pressed together, Df by SPDR at 0.0067 0.0067 not applicable for 10 GHZ further testing Tg by DMA (? C.) 229 199 Td by TGA (? C.) 344 345

[0149] Examples 1 to 7 show that the present resin compositions provide a feasible prepreg solutions with good storage stability. If high heat resistance is demanded as an additional property, examples 1 to 6 as compared to example 7 show that polyisocyanates having isocyanurate structures (examples 1 to 6) should rather be used than asymmetric trimers (example 7).

[0150] Comparative Example 1 (10% IPDI trimer+90% HDI trimer) and Comparative Example 4 (20% IPDI trimer+80% PDI trimer) show that a low content of IPDI trimer also leads to low Tg.

[0151] Comparative Example 2 shows (i) that the Tg for the system is too low to meet CCL application requirement and (ii) that a system with only aliphatic polyisocyanates is almost fully cured already after the first curing step, during the second curing step, only slight NCO groups were further consumed, which will result in bad adhesion or interlay strength for making composites, This problem was shown as in Comparative application example 1.

[0152] Comparative Example 3 shows that pure aromatic trimer will make the system moisture sensitive and will quickly become a high viscosity system which can't be easily used to impregnate the fiber. During the storage, the free isocyanate will be easily consumed, so that not enough residual NCO-content is left for the second curing step further pressing. Thus, this system is not practical for industrial application.