Accelerated curing of unsaturated polymer resins

Abstract

The invention relates to the cold curing and warm curing of unsaturated polyester resins, such as polyester resins and methyl methacrylate resins using mercaptans as reaction accelerators.

Claims

1. A method for curing an unsaturated polymer resin, comprising radically polymerizing the unsaturated polymer resin with one or more copolymerizable monomers and less than 1 ppm metals and metal salts, wherein an initiator system is used that comprises one or more organic peroxides and one or more mercaptans.

2. A method for curing an unsaturated polymer resin, comprising radically polymerizing the unsaturated polymer resin with one or more copolymerizable monomers and less than 1 ppm of metals and metal salts, wherein an initiator system is used that comprises one or more organic peroxides and one or more mercaptans, wherein the radical polymerization is carried out with 0 ppm in of tertiary amines.

3. The method according to claim 1, wherein the unsaturated polymer resin is selected from a group consisting of unsaturated polyester resins (UP resins), methyl methacrylate resins and vinyl ester resins.

4. The method according to claim 1, wherein the unsaturated polymer resin comprises an orthophthalic-acid-based UP resin.

5. The method according to claim 1, wherein the mercaptan is selected from a group consisting of glycol dimercaptoacetate (GDMA), pentaerythritol tetrakis (3-mercaptopropionate) (PETMP), isooctyl thioglycolate (IOTG) and combinations thereof.

6. The method according to claim 1, wherein the copolymerizable monomers are selected from a group consisting of styrene, -methyl styrene and methyl methacrylate.

7. The method according to claim 1, wherein the organic peroxide is selected from a group consisting of cumyl hydroperoxide (CUHP), dicumyl peroxide (DCUP), tert-butylperoxy-2-ethylhexanoate (TBPEH), tert-butyl peroxy-3,5,5-trimethylhexanoate (TBPIN), optionally in solution with acetylacetone, tert-butyl peroxybenzoate (TBPB), optionally in solution with acetylacetone, dilauroyl peroxide (LP), bis-(4-tert-butylcyclohexyl)-peroxydicarbonate (BCHPC), dimyristyl peroxydicarbonate (MYPC), tert-butylperoxy-2-ethylhexylcarbonate (TBPEHC), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (DHBP), methyl isobutyl ketone peroxide (MIKP), tert-amylperoxy-2-ethylhexanoate (TAPEH) and combinations thereof, such as BCHPC and MYPC.

8. The method according to claim 1, wherein the mercaptan comprises PETMP and the organic peroxide comprises BCHPC and/or MIKP.

9. The method according to claim 1, wherein the curing comprises radical polymerization at a temperature in the range of from approx. 40-150 C.

10. The method according to claim 1, wherein the curing comprises radical polymerization at a temperature of less than 40 C.

11. A composition comprising an unsaturated polymer resin, one or more mercaptans and one or more organic peroxides, wherein the amount of metals and metal salts in the composition is less than 1 ppm.

12. A kit comprising: (i) at least one unsaturated polymer resin and (ii) an initiator composition comprising one or more mercaptans and one or more organic peroxides, wherein the kit has less than 1 ppm metals and metal salts.

13. The method according to claim 1, wherein the curing comprises radical polymerization at a temperature of between 18-35 C.

14. The method according to claim 1, wherein the curing comprises radical polymerization at a temperature of between 20-30 C.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the curing curve for the reaction of an orthophthalic-acid-based unsaturated polyester resins (Palatal P4) with 1% BCHPC at a slightly increased temperature of 40 C. in the presence of various mercaptans.

(2) FIG. 2 shows the curing curve for the cold curing of Palatal P4 at a temperature of 25 C. using the organic peroxide BCHPC (2%) in the presence of various mercaptans.

(3) FIG. 3 shows the curing curve for the curing of Palatal P4 at a slightly increased temperature of 40 C. using 1% CUROXI-300 (MIKP) in the presence of different mercaptans and cobalt octoate as a comparative example.

(4) FIG. 4 shows the curing curve for the warm curing of Palatal P4 at 100 C. using 1% TBPB-HA-M3 in combination with the mercaptan PETMP or cobalt octoate as a comparative example.

(5) FIG. 5 shows the curing curve for the warm curing of Palatal P4 at 80 C. using 1.5% CUHP (80% solution) in combination with the mercaptan PETMP or with cobalt octoate and dimethylaniline (cobalt/amine) as a comparative example.

(6) FIG. 6 shows the curing curve for the warm curing of Palatal P4 at 100 C. using 1% TBPIN in combination with the mercaptan PETMP or 0.5% cobalt octoate as a comparative example.

(7) FIG. 7 is a graph of the curing curve for the warm curing of Palatal P4 at 100 C. using 1% TBPEH in combination with the mercaptan PETMP, with and without the addition of calcium hydroxide and cobalt octoate as a comparative example.

(8) FIG. 8 shows the curve of the curing of Palatal P4 at 100 C. using TBPEHC in combination with the mercaptan PETMP, with and without the addition of calcium hydroxide and cobalt octoate as a comparative example.

(9) FIG. 9 shows the curve of the warm curing of Palatal P4 at 60 C. using dilauroyl peroxide in combination with the mercaptan PETMP, with and without the addition of dimethylaniline, and with cobalt octoate as a comparative example.

(10) FIG. 10 shows the warm curing of Palatal P4 at 100 C. using 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DHBP) in combination with different mercaptans (PETMP, IOTG or GDMA, 1.0% in each case). Curing in the presence of tert-butyl-peroxybenzoate (TBPB) without the addition of mercaptan is shown as a comparative example.

(11) FIG. 11 shows the curing curve for the warm curing of Palatal P4 with BCHPC alone or in combination with MYPC at 60 C. Curing with and without the addition of 0.1% PETMP as an accelerator was investigated.

(12) FIG. 12 shows the curing curve for the methyl methacrylate resin Degadur 1008 using 1% TBPEH alone or in combination with the mercaptans PETMP, IOTG or GDMA, at 1.0% in each case.

(13) FIG. 13 shows the curing curve for the warm curing of the vinyl ester resin Derakane 411-350 using BCHPC alone or in combination with the mercaptans PETMP, IOTG or GDMA.

(14) FIG. 14 shows the curing curve for the cold curing of Palatal P6 at a temperature of 25 C. using the organic peroxide TAPEH in different concentrations (0.5%, 0.8%, 1.0%, 1.5% and 2.0%) in the presence of the mercaptan PETMP (0.05% Thiocure PETMP, 50% in Rhodiasolv).

(15) FIG. 15 shows the curing curve for the curing of Palatal P4 at a slightly increased temperature of 40 C. using 1% BCHPC in the presence of the mercaptan PETMP in a concentration of 0.2% or 0.5%. The combination of 1% BCHPC with 0.2% or 0.5% cobalt octoate Co-1 is shown as a comparative example.

EXAMPLES

(16) Description of the Experiment:

(17) The following measurements were taken in accordance with the DIN 19645 standard:

(18) Block curing 20 g of an unsaturated polymer resin in double-walled test tubes (air gap) in the water/oil bath, recording the exothermic reaction by means of PT-100 thermoelements using time recording.

(19) The alternative accelerators GDMA, PETMP and IOTG were used as 10% solutions in ethyl acetate in order to allow a more precise dosage. In addition, Thiocure PETMP was used as a 50% solution in Rhodiasolv.

(20) A medium-reactive standard resin Palatal P4 or P6 from DSM was selected as the orthophthalic acid resin. Degadur 1008 from Evonik was used as the methyl methacrylate and Derakane 411-350 from Ashland was used as the vinyl ester resin.

(21) The accelerators mentioned below in the series of experiments are dosed as a solution in the following composition:

(22) TABLE-US-00001 Co-1 1% cobalt octoate solution in aliphatic ester DMA 10% solution of dimethylaniline in styrene CA-12 10% solution of dimethylaniline + 2% cobalt octoate in aliphatic ester

(23) The following are stated as mercapto accelerators:

(24) TABLE-US-00002 PETMP 10% solution of pentaerythritol tetra-3-mercaptopropionate in ethyl acetate (unless otherwise stated) GDMA 10% solution of glycol dimercaptoacetate in ethyl acetate IOTG 10% solution of isooctyl thioglycolate in ethyl acetate

(25) Other solvents are also possible in addition to ethyl acetate (esters, alcohols, etc.).

(26) The stated percentages relate to weight ratios (w/w). In the dosage quantity for the peroxides, the stated quantity relates to the quantity of peroxide that is added to the 100% resin. For the accelerators, the stated dosage likewise relates to the quantity of accelerator solution that is added to the 100% resin.

(27) 1. Cold Curing or Curing at Slightly Increased Temperatures (40 C.) of Orthophthalic Acid Resins

(28) 1.1 Curing at 40 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% BCHPC

(29) TABLE-US-00003 Mercapto Gel Curing Bath Peroxide accelerator time in time in Exothermic temperature (1%) solution min min peak in C. in C. BCHPC none 94 120 136 40 BCHPC 1% PETMP 30 39 131 40 BCHPC 1% IOTG 12 21 139 40 BCHPC 1% GDMA 24 34 138 40

(30) The results are shown in FIG. 1.

(31) 1.2 Curing at 25 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 2% BCHPC

(32) TABLE-US-00004 Mercapto Gel Curing Bath accelerator time in time in Exothermic temperature Peroxide solution min min peak in C. in C. BCHPC 1% PETMP 38 57 111 25 (2%) BCHPC 1% IOTG 12 26 123 25 (2%) BCHPC 1% GDMA 31 48 120 25 (2%)

(33) The results are shown in FIG. 2.

(34) 1.3 Curing at 40 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% CUROX I-300 (MIKP)

(35) TABLE-US-00005 Bath Peroxide Mercapto Gel time in Curing time Exothermic temperature in (1%) accelerator solution Accelerator min in min peak in C. C. Curox I- 67 99 136 40 300 Curox I- 0.50% Co-1 27 29 153 40 300 Curox I- 1% PETMP 22 46 133 40 300 Curox I- 1% IOTG 22 58 113 40 300 Curox I- 1% GDMA 19 42 132 40 300

(36) The example shows that methyl isobutyl ketone peroxide (MIKP) is in principle capable of acceleration, but the efficiency of cobalt octoate is not reached since although the reaction with thioesters begins at an early stage, it proceeds somewhat more slowly. The results are shown in FIG. 3.

(37) 1.4 Curing at 25 C. Bath Temperature, Palatal P6, DIN 19645, Acceleration of Thiocure PETMP and TAPEH

(38) TABLE-US-00006 Mercapto Gel Curing Bath accelerator time in time in Exothermic temperature Peroxide solution min min peak in C. in C. 0.5% 0.05% 107.7 133.8 68 25 TAPEH PETMP 0.8% 0.05% 65.5 87.7 152 25 TAPEH PETMP 1.0% 0.05% 54.4 73 161 25 TAPEH PETMP 1.5% 0.05% 38.4 53.9 172 25 TAPEH PETMP 2.0% 0.05% 28.8 44.5 174 25 TAPEH PETMP

(39) PETMP was used as a 50% solution in Rhodiasolv (methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate).

(40) The example shows that the curing speed increases when the peroxide quantity increases and the PETMP quantity remains the same. The results are shown in FIG. 14.

(41) 1.5 Curing at 40 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% BCHPC in Combination with PETMP or Co-1

(42) TABLE-US-00007 Bath Peroxide Mercapto Gel time in Curing time Exothermic temperature in (1%) accelerator solution Accelerator min in min peak in C. C. BCHPC 0.2% PETMP 24.3 36 133 40 BCHPC 0.5% PETMP 21.2 30.8 134 40 BCHPC 0.2% Co-1 68.3 115 141 40 BCHPC 0.5% Co-1 156 172 133 40

(43) PETMP was used as a 10% solution in ethyl acetate.

(44) The example shows that, when using BCHPC, the curing speed barely increases at all by adding the cobalt accelerator Co-1, while even small quantities of the mercaptan PETMP cause a significant increase in the curing speed. The results are shown in FIG. 15.

(45) 2. Warm Curing and Hot Curing of Orthophthalic Acid Resins

(46) The standard accelerator cobalt octoate or the combination of cobalt octoate with a dimethylaniline solution was replaced by different mercaptans.

(47) 2.1 Curing at 100 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% TBPB-HA-M3

(48) TABLE-US-00008 Bath Mercapto Accelerator Gel time in Curing time Exothermic temperature in Peroxide accelerator solution solution min in min peak in C. C. TBPB- 35 39 220 100 HA-M3 TBPB- 1% PETMP 16 19 213 100 HA-M3 TBPB- 0.5% Co-1 13 15 207 100 HA-M3

(49) It has been demonstrated that a cobalt octoate accelerator can be replaced by the mercapto accelerator PETMP with very similar efficiency. The results are shown in FIG. 4.

(50) 2.2 Curing at 80 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1.5% CUHP 80%

(51) TABLE-US-00009 Bath Mercapto Accelerator Gel time in Curing time Exothermic temperature in Peroxide accelerator solution solution min in min peak in C. C. CUHP 39 54 175 80 80% CUHP 1% PETMP 19 25 193 80 80% CUHP 0.5% CA-12 21 25 198 80 80%

(52) It has been demonstrated that a highly efficient cobalt/amine accelerator can be replaced by the mercapto accelerator PETMP with equivalent efficiency. The results are shown in FIG. 5.

(53) 2.3 Curing at 100 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% TBPIN

(54) TABLE-US-00010 Mercapto Gel Curing accelerator Accelerator time in time in Exothermic Peroxide solution solution min min peak in C. TBPIN 27 31 217 TBPIN 1% PETMP 12 14 207 TBPIN 0.5% Co-1 17 20 209

(55) It has been demonstrated that greater acceleration effects can in fact be achieved in the group of peroxyesters compared with the widely used cobalt octoate. The results are shown in FIG. 6.

(56) 2.4 Curing at 100 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% TBPEH

(57) TABLE-US-00011 Mercapto Accelerator Gel Curing Peroxide accelerator or inhibitor time in time in Exothermic (1.0%) solution solution min min peak in C. TBPEH 14.6 17.1 210 TBPEH 1% PETMP 9.5 11.4 20.4 TBPEH 0.5% Co-1 12.0 14.5 205 TBPEH 1% PETMP 0.5% Ca 12.4 14.2 210 hydroxide

(58) It is clear that, in addition to replacing cobalt octoate as the accelerator, it is possible to delay the reaction by shifting the pH by means of calcium hydroxide. The results are shown in FIG. 7.

(59) 2.5 Curing at 100 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% TBPEHC

(60) TABLE-US-00012 Mercapto Accelerator Gel Curing Peroxide accelerator or inhibitor time in time in Exothermic (1%) solution solution min min peak in C. TBPEHC 26 29 219 TBPEHC 1% PETMP 16 19 210 TBPEHC 0.5% Co-1 27 31 215 TBPEHC 1% PETMP 0.5% 20 23 216 calcium hydroxide

(61) It is clear that TBPEHC cannot be accelerated by cobalt octoate, but that PETMP significantly reduces the reaction time, which is in turn slowed by calcium hydroxide. The results are shown in FIG. 8.

(62) 2.6 Curing at 60 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% Dilauroyl Peroxide LP

(63) TABLE-US-00013 Mercapto Bath Peroxide accelerator Accelerator Gel time Curing time Exothermic temperature (1%) solution solution in min in min peak in C. in C. LP 110 124 152 60 LP 1% PETMP 92 110 148 60 LP 1% PETMP 0.5% DMA 46 57 157 60 LP 0.5% Co-1.sup. 104 117 157 60 LP 0.5% DMA 59 69 160 60

(64) It is clear that cobalt octoate has barely any accelerating effect on LP, and by contrast significantly accelerates a dimethylaniline but could certainly be replaced by PETMP. The results are shown in FIG. 9.

(65) 2.7 Curing at 110 C. Bath Temperature, Palatal P4, DIN 19645, Acceleration of 1% Dialkyl Peroxide DHBP

(66) TABLE-US-00014 Mercapto Gel Curing Bath Peroxide accelerator time in time in Exothermic temperature (1%) solution min min peak in C. in C. DHBP 37 41 231 110 DHBP 1.0% PETMP 35 39 230 110 DHBP 1.0% IOTG 24 28 224 110 DHBP 1.0% GDMA 29 34 229 110 TBPB 21 24 225 110

(67) It is clear that a dialkyl peroxide, which is usually not used in the hot curing of polyester resins due to its high thermal stability, can be activated by mercapto accelerators such that curing times are achieved that are considerably closer to the standard hot-pressing process using the peroxide TBPB, and this approach could potentially replace said method. The results are shown in FIG. 10.

(68) 2.8 Reduced Dosage of the PETMP in the Curing of Orthophthalic Acid Resin Palatal P4 with a 1% BCHPC and MYPC Mixture in a 1:1 Ratio at 60 C., DIN19645

(69) TABLE-US-00015 Mercapto Gel Curing Bath Peroxide accelerator time in time in Exothermic temperature (1%) solution min min peak in C. in C. BCHPC 27 132 168 60 1:1 BCHPC + 31 37 159 60 MYPC 1:1 BCHPC + 0.1% PETMP 20 26 145 60 MYPC

(70) It is clear that significant accelerations can be achieved even with small quantities of PETMP (100 ppm pure substance), even if peroxide mixtures that exhibit slower behaviour are used. The results are shown in FIG. 11.

(71) 3. Curing of Other Resin Systems

(72) 3.1 Curing at 60 C. Bath Temperature, Methyl Methacrylate Resin Degadur 1008 (Evonik), DIN 19645, Acceleration of 1% TBPEH

(73) TABLE-US-00016 Mercapto Gel Curing Bath Peroxide accelerator time in time in Exothermic temperature (1%) solution min min peak in C. in C. TBPEH 109 122 134 60 TBPEH 1.0% PETMP 83 100 124 60 TBPEH 1.0% IOTG 96 114 141 60 TBPEH 1.0% GDMA 88 108 142 60

(74) The results are shown in FIG. 12.

(75) 3.2 Curing at 60 C. Bath Temperature, Vinyl Ester Resin Derakane 411-350 (Ashland), DIN 19645, Acceleration of 1% BCHPC

(76) TABLE-US-00017 Mercapto Gel Curing Bath Peroxide accelerator time in time in Exothermic temperature (1%) solution min min peak in C. in C. BCHPC None 26 30 178 60 BCHPC 0.5% PETMP 23 28 173 60 BCHPC 0.5% IOTG 21 25 176 60 BCHPC 0.5% GDMA 22 26 173 60

(77) Accelerating effects can also be expected in other resin systems, as in this example with vinyl ester resin, although not to the same extent as for unsaturated polyester resins. The results are shown in FIG. 13.