Phosphorus-containing compounds useful for making halogen-free, ignition-resistant polymers

Abstract

A process for making a phosphorus-containing compound is disclosed. The process comprises contacting a compound of formula (A) wherein R.sup.A and R.sup.B are selected from optionally substituted aryl, aryloxy, alkyl and alkoxy groups or can be combined to form cyclic structures; and R.sup.C is methyl, ethyl, isopropyl, n-butyl, i-butyl, t-butyl, phenyl or benzyl; and a compound of formula (B) wherein R.sup.1-R.sup.4 are selected from optionally substituted aryl, aryloxy, alkyl and alkoxy groups. The phosphorus-containing compound can then be used as a flame retardants for polymers, especially for epoxy, polyurethane, thermosetting resins and thermoplastic polymers. Such flame retardant-containing polymers can be used to make protective coating formulations and ignition-resistant fabricated articles, such as electrical laminates, polyurethane foams, and various molded and/or foamed thermoplastic products.

Claims

1. A process for making a curable phosphorus-containing epoxy resin composition comprising blending: (I) a phosphorus-containing compound comprising the reaction product of: ##STR00016## wherein R.sup.A and R.sup.B, independently of one another, are selected from the group consisting of substituted aryl groups, substituted aryloxy groups, unsubstituted aryl groups, unsubstituted aryloxy groups, substituted alkyl groups, and unsubstituted alkyl groups; or wherein R.sup.A and R.sup.B are be combined to form cyclic structures; wherein R.sup.c is a hydrocarbyl radical containing in the range of from 1 to 12 carbon atoms per molecule and is selected from the group consisting of methyl, ethyl, isopropyl, n-butyl, i-butyl, t-butyl, phenyl, and benzyl; and ##STR00017## wherein R.sup.1-R.sup.4, independently from one another, are selected from the group consisting of hydrogen, a substituted alkyl group, a substituted alkoxy group, an unsubstituted alkyl group, an unsubstituted alkoxy group, a substituted aryl group, a substituted aryloxy group, an unsubstituted aryl group and an unsubstituted aryloxy group; (II) at least one epoxy resin; and (III) at least one catalyst.

2. A phosphorus-containing compound prepared by a process comprising contacting: ##STR00018## wherein R.sup.A and R.sup.B, independently of one another, are selected from the group consisting of substituted aryl groups, substituted aryloxy groups, unsubstituted aryl groups, unsubstituted aryloxy groups, substituted alkyl groups, and unsubstituted alkyl groups; or wherein R.sup.A and R.sup.B are be combined to form cyclic structures; wherein R.sup.C is a hydrocarbyl radical containing in the range of from 1 to 12 carbon atoms per molecule and is selected from the group consisting of methyl, ethyl, isopropyl, n-butyl, i-butyl, t-butyl, phenyl, and benzyl; and ##STR00019## wherein R.sup.1-R.sup.4, independently from one another, are selected from the group consisting of hydrogen, a substituted alkyl group, a substituted alkoxy group, an unsubstituted alkyl group, an unsubstituted alkoxy group, a substituted aryl group, a substituted aryloxy group, an unsubstituted aryl group and an unsubstituted aryloxy group.

3. A phosphorus-containing compound prepared by a process comprising contacting: ##STR00020## wherein R.sup.1-R.sup.4, independently from one another, are selected from the group consisting of hydrogen, a substituted alkyl group, a substituted alkoxy group, an unsubstituted alkyl group, an unsubstituted alkoxy group, a substituted aryl group, a substituted aryloxy group, an unsubstituted aryl group and an unsubstituted aryloxy group.

4. A varnish produced from the composition of claim 1.

5. A prepreg prepared from the varnish of claim 4.

6. An electrical laminate prepared from the varnish of claim 4.

7. A printed circuit board prepared from the varnish of claim 4.

8. A coating prepared from the composition of claim 1.

9. A composite prepared from the composition of claim 1.

10. A casting prepared from the composition of claim 1.

11. An adhesive prepared from the composition of claim 1.

12. The process of claim 1, wherein compound (B) is defined by the following formula: ##STR00021##

13. The process of claim 1, wherein compound (B) is defined by the following formula: ##STR00022##

14. The process of claim 1, wherein compound (B) is defined by the following formula: ##STR00023##

Description

EXAMPLES

(1) The following examples are intended to be illustrative of the present invention and to teach one of ordinary skill in the art to make and use the invention. These examples are not intended to limit the invention in any way.

(2) Synthesis of DOP-OMe

(3) In a 1 liter reactor, 23.5 grams (0.1 mol) of DOP-Cl and 10.1 grams (0.1 mol) of triethylamine was added to 100 mL of stirring toluene under nitrogen. The mixture was cooled using an ice/salt bath. A 3.2 gram quantity (0.1 mol) of methanol was added slowly via addition funnel keeping the reaction temperature at 0-10 C. After the addition of methanol was completed, the cooling bath was replaced with a heating mantle and the reaction mixture was heated to 50 C. and stirred continuously for an additional 3 hours. The heating mantle was then removed and the reaction mixture was allowed to cool to room temperature. The triethylamine hydrochloride salt was filtered off and the filtrate was concentrated using the rotary evaporator under full vacuum keeping the bath temperature below 100 C. Crude yield of DOP-OMe: 90%, light yellow oil. The product could be used for the next step without further purification.

(4) Synthesis of tetramethylol Bis-A

(5) A 110.5 gram quantity (0.48 mol) of DOP-OMe and 34.7 grams (0.1 mol) of tetramethylol Bis-A were weighed out into a 500 mL one neck RB flask. The mixture was then attached to a Kugelrohr set-up with one receiving flask. The flasks were secured by applying 200 mm vacuum using a vacuum pump. The heating chamber was heated to 100 C. and was kept at that temperature for 30 minutes upon which methanol started condensing in the receiving flask. The reaction mixture was then heated slowly to 170 C. over 30 minutes and was kept at that temperature for another 30 minutes. The heating was then stopped and the formed solid was allowed to cool to room temperature. The reaction flask was then removed and 200 mL of chloroform was added to dissolve the solid product. The solution was transferred to an Erlenmeyer flask. While stirring, 100 mL of diethylether was added. The precipitated white solid was suction filtered using vacuum and was dried in a vacuum oven at 50 C. Crude yield: 101 grams of t-mDOP Bis-A

(6) Evaluation of t-mDOP Bis A in an Epoxy Formulation

(7) Control Formulation:

(8) A comparison was made using a halogen free phosphorus functionalized control formulation containing XZ-92741, a commercial hardener available from The Dow Chemical Company. The components used in the formulation are given in the table below.

(9) TABLE-US-00001 Designation Description DEN 438 Liquid epoxy novolac resin having an epoxide equivalent weight Liquid epoxy novolac resin, available from The Dow Chemical Company XZ-92741 Phosphorus containing epoxy hardener available from The Dow Chemical Company DICY Dicyandiamide MEK Methyl ethyl ketone (an organic solvent) 2-PI 2-Phenyl imidazole

(10) The comparison was done by replacing XZ-92741 with t-mDOP Bis-A. Preparation of the varnish was accomplished following the procedure below. 1. Prepare 10 wt. % DICY solution using dimethylformamide as a solvent 2. Prepare 20 wt. % solution of 2-phenylimidazole (2-PI) using DOWANOL PM as a solvent 3. Add the DICY and 2-PI solution (2-PI) to XZ 92741.00 Hardener and stir until a homogeneous solution is obtained. 4. Add DEN 438 Epoxy Resin Solution

(11) Stroke cure reactivity is determined using IPC-TM-650 No. 2.3.17. A timer was started as soon as 1.5 ml of the varnish was placed on a hotplate at 171 C. The varnish was left to sit on the hot plate for one minute prior to being manipulated with a wooden tongue depressor in order to evaporate residual solvent. The varnish was manipulated and mixed and determined to be gelled when the material could not form strings when lifted from the surface of the hot plate. The total time was recorded as the stroke cure reactivity or gel time.

(12) The gelled resin was then collected and placed in an oven at 190-200 C. to post cure for 1.5 h. Small pieces of the post cured resin were placed in a thermal gravimetric analyzer (TGA Q50 or 2050, TA Instruments) to obtain a decomposition temperature, T.sub.d, which is defined as the temperature at which 5% weight loss of the sample occurs. The TGA measurements were done at a heating rate of 10/min under nitrogen atmosphere. The resin was also analyzed using differential scanning calorimeter (DSC Q1000, TA Instruments) to measure the glass transition temperature, T.sub.g of the formulation. The method used was IPC TM-650 2.4.25.

(13) TABLE-US-00002 DSC Method 1 Equilibrate at 40 C. 2 Ramp 10.00 C./min to 220 C. 3 Equilibrate at 200 C. 4 Isothermal for 15 min 5 Equilibrate at 40 C. 6 Ramp 10.00 C./min to 220 C. 7 Equilibrate at 40 C. 8 Ramp 20.00 C./min to 220 C.

(14) Comparison was done between a formulation containing XZ-92741, a proprietary phosphorus containing Epoxy resin and a formulation where XZ-92741 is replaced by t-mDOP Bis-A. The formulation was done at the same wt. % P loading. The glass transition temperature (Tg) was measured by DSC using a TA Instruments Model Q2000 DSC.

(15) The inventive example formulation is shown in Table I below.

(16) TABLE-US-00003 TABLE I Inventive Control Example Material Solids % Solids % D.E.N.438 [85% solids in 63.00 68.79 MEK] XZ-92741 (59% solids in MEK) 37.00 t-mDOP Bis-A 30.56 Dicy (10 wt % in DMF) 2.40 3.05 2-PI (20 wt. % in Dowanol PM 1.60 1.60 % P 3.20 3.20 Epoxy:hardner ratio 1.24 1.24

(17) The T.sub.g values for the control and inventive examples are shown in Table II, below.

(18) TABLE-US-00004 TABLE II Reactivity (s) T.sub.g1 ( C.) T.sub.g2 ( C.) T.sub.g3 ( C.) T.sub.d ( C.) Control 164 167 168 169 349 t-mDOP 205 172 175 178 354 Bis-A

(19) The data shows that t-mDOP Bis-A formulation shows improved Tg.