Patent Number: 047217383
Section: description

EXAMPLE 1 Polyethylene (45 g) is blended with 1% and 2%, by weight, of Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH). These samples and a polyethylene control are processed in a Brabender mixer at 40 rpms at 160.degree. C. After 15 minutes the samples are removed from the mixer while still hot. The samples are compression molded at 325.degree. F. and 36 tons in a 21/4".times.5".times.1/8" plaque mold and the plaques are used to measure sensitivity to microwave energy in the RF region by irradiating the sample at 61-85 cm..sup.-1. (Unless indicated otherwise, all samples were tested for sensitivity to microwave heating by irradiation at 61-85 cm.sup.-1 using a Thermall EO-1 RF generator and made by W. T. LaRose Associates, Cohoes, N.Y.) Minor heat absorption of the samples is noted at 130 milliamps once a threshold temperature is reached; however, as shown below at higher powers much more heat absorption is obtained. EXAMPLE 2 Plaque samples of the formulations given in Table 1 are made up as in Example 1, except that the samples are of the dimensions 11/2".times.21/2".times.1/8". The temperature of the samples as a function of exposure to microwave radiation is measured as follows: Two plaques, one on top of the other, are supported on a 11/2".times.21/2".times.1/8" aluminum plate which acts as a heat sink. The temperature of the inner surfaces of the plaques is measured with a surface pyrometer for five successive 60 second pulses. The initial current is 370 milliamps. After each series the aluminum plate is cooled to room temperature. The results are summarized in Table 1. TABLE 1 ______________________________________ Pulse 1st 2nd 3rd 4th 5th Formulation .degree.F. .degree.F. .degree.F. .degree.F. .degree.F. ______________________________________ Polyethylene (Control) 68 81 87 94 101 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH).sub.2 White 86 93 102 109 115 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH).sub.2 Red 82 94 105 115 121 2% Zr(O.sub.3 PCH.sub.2 OH).sub.2 101 123 132 138 140 2% Ti(O.sub.3 PC.sub.6 H.sub.5).sub.2 87 102 110 118 129 5% Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH).sub.2 98 117 132 144 150 Polyethylene (Control).sup.a 84 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH)White.sup.a 93 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH)Red.sup.a 80 ______________________________________ .sup.a Samples tested again to make sure repeated residual heat buildup has no bearing on the magnitude of the sensitivity to microwave RF heating. It is clear from the results of Table 1 that the particulate layered compounds utilized in this experiment sensitize polyethylene to microwave heating, in the RF range. EXAMPLE 3 The samples of Table 2 are made in a Brabender plsticorder using a polyethylene as the nonpolar polymer. Each is tested as in Example 2 and the results obtained are summarized in Table 2. TABLE 2 __________________________________________________________________________ Pulse Additive 1st .degree.F. 2nd .degree.F. 3rd .degree.F. 4th .degree.F. 5th .degree. F. __________________________________________________________________________ None 77 86 93 99 104 2% Et/CO Copolymer.sup.b 88 118 138 150 156 2% Asbestos 125 161(fusion) -- -- -- 5% Asbestos 144(fusion) -- -- -- -- 2% Zr(O.sub.3 PCH.sub.2 OH).sub.2 108 127 143 148 157 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 120 153 166 186 186 2% Vinylalcohol 115 159 187 200 -- (fusion) 4% ET/CO Copolymer 141 178 197 -- -- Repeats (see footnote .sup.a above) None 86 103 115 121 128 2% Et/CO.sup.b 114 145 159 166 173 Copolymer __________________________________________________________________________ .sup.b An ethylenecarbon monoxide copolymer prepared by peroxidecatalyzed polymerization. The sample comprising 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 is superior to the samples comprising the prior art microwave enegy sensitizers. Moreover, in addition to its safety advantage over asbestos, the current drift over a 60 second time period is very small (7%) while asbestos shows a greater than 10% current drift and premature fusion. EXAMPLE 4 The formulation of Table 3, using a polyethylene, available from Exxon, were made in a Bradbender Plasticcorder, molded, then subjected to microwave energy as in Example 2. TABLE 3 ______________________________________ Pulse 1st 2nd 3rd 4th 5th Additive .degree.F. .degree.F. .degree.F. .degree.F. .degree.F. ______________________________________ None 97 107 125 137 144 0.5% Asbestos 101 123 139 146 156 0.5% Zr(O.sub.3 PCH.sub.2 CHOH).sub.2 103 125 137 149 153 1.0% Asbestos 136 174 -- -- -- 1.0% Zr(O.sub.3 PCH.sub.2 CHOH).sub.2 117 142 150 162 164 0.75% Asbestos 110 139 168 189 -- 0.75% Zr(O.sub.3 PCH.sub.2 CH).sub.2 106 134 148 156 162 1.25% Zr(O.sub.3 PCH.sub.2 CH).sub.2 117 145 157 164 172 0.5% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH) 94 114 131 140 146 0.75% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 98 116 127 136 143 1.0% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 91 108 122 132 138 1.25 Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 98 122 135 144 151 ______________________________________ Room Temperature 68.degree. F. Pulses are 60 seconds each at 376 milliamps Titanium layered compounds powder more easily and may be more compatible with polyethylene than is its zirconium cogener; however the titanium layered compounds are not quite as good as zirconium - especially for pulses less than 180 seconds. Nevertheless both compositions are efficient microwave sensitizers for polyethylene. In addition, the temperature rise magnitude for successive pulses decreases whith increasing temperature of the polymer compositions of this invention as compared to the asbestos-containing polymer compositions and the polymer alone. This property is, of course, desirable and unexpected. EXAMPLE 5 In this Example the plaques are shielded by a 1/4" Teflon.RTM. ring. The results are summarized in Table 4 below. TABLE 4 __________________________________________________________________________ Pulse Additive 1st 2nd 3rd 4th 5th __________________________________________________________________________ None 72 82 92 99 104 2 Teflon 0.5% Asbestos 87 102 111 120 127 ring shields None 84 95 101 107 113 2 Teflon 2% Zr(O.sub.3 PCH.sub.2 OH) 108 127 137 141 149 ring shields 2% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 126 160 162 -- -- __________________________________________________________________________ It is hypothesized OH in that compound is less sterically hindered and can therefore vibrate more freely. All five pulses are done sequentially. Each sequence starts at ambient temperature (72.degree. F.) The aluminum plate is washed in water to remove heat buildup. In this experiment, the edges of the aluminum plates are rounded so that the bottom of the RF chamber won't be damaged by accidental arcing. The Teflon rings ensure that the sample plaques are affected only by direct radiation and not refracted energy. EXAMPLE 6 The formulations of Table 5 were made and tested as in Example 5. TABLE 5 ______________________________________ Pulse 1st 2nd 3rd 4th 5th Additive .degree.F. .degree.F. .degree.F. .degree.F. .degree.F. ______________________________________ None 84 95 104 114 119 0.5% Asbestos 99 114 125 130 137 0.75% Asbestos 124 157 166* -- -- 1.0% Asbestos 135 170 -- -- -- 0.5% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 92 103 112 126 125 0.75% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 97 111 120 127 131 1.0% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 96 113 124 132 140 1.25% Ti((O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 99 113 124 130 137 0.5% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 91 104 111 118 119 0.75% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 106 124 137 142 149 1.0% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 112 130 140 143 153 1.25% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 112 128 142 149 155 2.0% Ti(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 100 115 125 132 138 ______________________________________ *Sample melted This sample demonstrates, again, that the additives of this invention are superior to the prior art asbestos additive because of the observed temperature leveling phenomenon. EXAMPLE 7 Silica (325 mesh) and Frequon 3035 (at 2.0 percent, by weight polymer) were evaluated for their ability to impart microwave sensitization in dielectric plastics. A formulation containing 0.75% asbestos and one containing 2.0% zirconium hydroxyethylphosphonate [ZR(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 ] were also tested. It was found that the Frequon 3035 had a useful microwave sensitivity, but the silica did not. The sensitivity characteristics of the Frequon 3035 were further evaluated, and the results are tabulated in Tables 6 and 7. Frequon 3035 is more effective than Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 ; however, this may be due to Frequon 3035's, generally, smaller particle size. TABLE 6 ______________________________________ MICROWAVE SENSITIVITIES (.degree.F.) ONE PULSE AT 370 MILLIAMPS FOR 60 SEC. NO SHIELDING ROOM TEMPERATURE TEMPERA- AFTER ONE ADDITIVE TURE CYCLE ______________________________________ None 62 82 2% Frequon 64 163 2% Zr (O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 65 122 0.75% Asbestos 71 123 4% Frequon 3035 69 181 (melts) 2% 325 Mesh Silica 66 89 5% 325 Mesh Silica 68 88 ______________________________________ TABLE 7 ______________________________________ MICROWAVE SENSITIVITIES THREE CYCLES OF 300 MILLIAMPS FOR 30 SECONDS NO SHIELDING ROOM T.degree. F. TEMPERA- PULSE NUMBER ADDITIVE TURE 1 2 3 ______________________________________ None 64 75 88 91 1% Frequon 3035 67 93 111 124 1.5% Frequon 3035 67 105 129 145 2.0% Frequon 3035 65 116 160 195* 2.0% Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 67 100 116 131 0.75 Asbestos 67 96 124 141 ______________________________________ *Sample melted EXAMPLE 8 Microwave sensitivity measurements were made in a polyethylene matrix on zirconium phosphate [Zr(O.sub.3 POH).sub.2 ] zirconium hydroxyethylphosphate [Zr(O.sub.3 POCH.sub.2 CH.sub.2 OH).sub.2 ], and zirconium hydroxyethylphosphonate [Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 ], using asbestos and a matrix without any additive as reference samples. The plaques were subjected to 370 milliamps for 60 seconds each. There was no cooling to room temperature in between the various samples, and no Teflon shielding was used to prevent effects of refracted radiation from having an effect on the sample. Room temperature was 64.degree. F. and this was true only for first pulse of control sample. The data taken are given in Table 8. The hydroxyethylphosphonate performs the best followed by the hydroxyethylphosphate and the phosphate, respectively. Sensitivity of the hydroxyethylphosphonate is of approximately the same magnitude as that of asbestos. Nytal 99 is an industrial talc from R. T. Vanderbilt, Inc. Talc is chemically similar to asbestos, and to some extent, has been used as a substitute for asbestos in some commercial applications. Obviously, this particular grade of talc is not appreciably microwave sensitive. In Table 9, the samples were shielded, as above, and allowed to equilibrate to room temperature between pulses. Otherwise the conditions were the same as in Table 9. TABLE 8 ______________________________________ Pulse No. (.degree.F.) Additive 1 2 3 4 5 ______________________________________ None 82 103 122 131 138 2% Zr (O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 122 164 -- -- -- 2% Nytal 99 94 112 130 142 150 2% Zr (O.sub.3 POCH.sub.2 CH.sub.2 OH).sub.2 106 140 157 175 -- 2% Zr (O.sub.3 POH).sub.2 95 117 139 154 164 0.75% Asbestos 147 186 -- -- -- ______________________________________ TABLE 9 ______________________________________ Pulse No. (.degree. F.) 1 2 3 4 5 ______________________________________ None 78 91 101 112 118 2% Zr (O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 116 143 165 -- -- 2% Nytal 99 83 97 110 118 127 2% Zr (O.sub.3 POCH.sub.2 CH.sub.2 OH).sub.2 98 127 139 151 163 2% Zr (O.sub.3 POH).sub.2 92 110 124 134 138 0.75% Asbestos 116 158 -- -- -- ______________________________________ While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto since many obvious modifications can be made and it is intended to include within this invention any such modifications as will fall within the scope of the appended claims.