EP0962815B1 - Recording material with improved image tone and/or stability upon thermal development - Google Patents
Recording material with improved image tone and/or stability upon thermal development Download PDFInfo
- Publication number
- EP0962815B1 EP0962815B1 EP19990201712 EP99201712A EP0962815B1 EP 0962815 B1 EP0962815 B1 EP 0962815B1 EP 19990201712 EP19990201712 EP 19990201712 EP 99201712 A EP99201712 A EP 99201712A EP 0962815 B1 EP0962815 B1 EP 0962815B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- silver
- recording material
- palmitate
- organic
- salt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000463 material Substances 0.000 title claims description 109
- 238000011161 development Methods 0.000 title description 4
- LTYHQUJGIQUHMS-UHFFFAOYSA-M silver;hexadecanoate Chemical compound [Ag+].CCCCCCCCCCCCCCCC([O-])=O LTYHQUJGIQUHMS-UHFFFAOYSA-M 0.000 claims description 110
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 claims description 63
- 239000006185 dispersion Substances 0.000 claims description 44
- -1 organic acid salts Chemical class 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 31
- 239000010410 layer Substances 0.000 claims description 27
- 239000002245 particle Substances 0.000 claims description 25
- 229910052709 silver Inorganic materials 0.000 claims description 24
- 239000004332 silver Substances 0.000 claims description 24
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 19
- 239000003638 chemical reducing agent Substances 0.000 claims description 17
- 239000003945 anionic surfactant Substances 0.000 claims description 15
- 239000007864 aqueous solution Substances 0.000 claims description 14
- 150000007524 organic acids Chemical class 0.000 claims description 14
- 238000002441 X-ray diffraction Methods 0.000 claims description 13
- 239000011230 binding agent Substances 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 235000021314 Palmitic acid Nutrition 0.000 claims description 11
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 claims description 11
- 239000011241 protective layer Substances 0.000 claims description 11
- 239000003513 alkali Substances 0.000 claims description 9
- 239000012736 aqueous medium Substances 0.000 claims description 7
- 238000000108 ultra-filtration Methods 0.000 claims description 7
- 150000001447 alkali salts Chemical group 0.000 claims description 6
- 150000003863 ammonium salts Chemical class 0.000 claims description 6
- 229910052753 mercury Inorganic materials 0.000 claims description 6
- 235000005985 organic acids Nutrition 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 5
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052593 corundum Inorganic materials 0.000 claims description 3
- 230000003472 neutralizing effect Effects 0.000 claims description 3
- 150000002942 palmitic acid derivatives Chemical class 0.000 claims description 3
- 239000010409 thin film Substances 0.000 claims description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims 1
- 150000004996 alkyl benzenes Chemical class 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 31
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 25
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
- 239000000243 solution Substances 0.000 description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 238000010438 heat treatment Methods 0.000 description 16
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 13
- 239000002253 acid Substances 0.000 description 12
- 239000008367 deionised water Substances 0.000 description 12
- 229910021641 deionized water Inorganic materials 0.000 description 12
- 238000003756 stirring Methods 0.000 description 12
- 238000002360 preparation method Methods 0.000 description 11
- 239000004094 surface-active agent Substances 0.000 description 11
- 150000007513 acids Chemical class 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 9
- 238000000576 coating method Methods 0.000 description 9
- 150000003378 silver Chemical class 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 229910001961 silver nitrate Inorganic materials 0.000 description 8
- 238000007639 printing Methods 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- 229940045870 sodium palmitate Drugs 0.000 description 7
- GGXKEBACDBNFAF-UHFFFAOYSA-M sodium;hexadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCC([O-])=O GGXKEBACDBNFAF-UHFFFAOYSA-M 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 150000004665 fatty acids Chemical class 0.000 description 6
- 229920000159 gelatin Polymers 0.000 description 6
- 235000019322 gelatine Nutrition 0.000 description 6
- 239000004615 ingredient Substances 0.000 description 6
- 238000001931 thermography Methods 0.000 description 6
- 108010010803 Gelatin Proteins 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 5
- 239000008273 gelatin Substances 0.000 description 5
- 235000011852 gelatine desserts Nutrition 0.000 description 5
- 239000000314 lubricant Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 235000014113 dietary fatty acids Nutrition 0.000 description 4
- 239000000194 fatty acid Substances 0.000 description 4
- 229930195729 fatty acid Natural products 0.000 description 4
- 229940042795 hydrazides for tuberculosis treatment Drugs 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 239000003607 modifier Substances 0.000 description 4
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 239000000725 suspension Substances 0.000 description 4
- 238000007651 thermal printing Methods 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 239000000975 dye Substances 0.000 description 3
- 239000000839 emulsion Substances 0.000 description 3
- 150000002148 esters Chemical class 0.000 description 3
- 239000004816 latex Substances 0.000 description 3
- 239000006224 matting agent Substances 0.000 description 3
- 239000002609 medium Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 description 3
- 239000005020 polyethylene terephthalate Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- DZAUWHJDUNRCTF-UHFFFAOYSA-N 3-(3,4-dihydroxyphenyl)propanoic acid Chemical compound OC(=O)CCC1=CC=C(O)C(O)=C1 DZAUWHJDUNRCTF-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- ZTHYODDOHIVTJV-UHFFFAOYSA-N Propyl gallate Chemical compound CCCOC(=O)C1=CC(O)=C(O)C(O)=C1 ZTHYODDOHIVTJV-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 150000007933 aliphatic carboxylic acids Chemical class 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 239000002216 antistatic agent Substances 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 150000001735 carboxylic acids Chemical class 0.000 description 2
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- KBPUBCVJHFXPOC-UHFFFAOYSA-N ethyl 3,4-dihydroxybenzoate Chemical compound CCOC(=O)C1=CC=C(O)C(O)=C1 KBPUBCVJHFXPOC-UHFFFAOYSA-N 0.000 description 2
- VFPFQHQNJCMNBZ-UHFFFAOYSA-N ethyl gallate Chemical compound CCOC(=O)C1=CC(O)=C(O)C(O)=C1 VFPFQHQNJCMNBZ-UHFFFAOYSA-N 0.000 description 2
- LNTHITQWFMADLM-UHFFFAOYSA-N gallic acid Chemical compound OC(=O)C1=CC(O)=C(O)C(O)=C1 LNTHITQWFMADLM-UHFFFAOYSA-N 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- FBSFWRHWHYMIOG-UHFFFAOYSA-N methyl 3,4,5-trihydroxybenzoate Chemical compound COC(=O)C1=CC(O)=C(O)C(O)=C1 FBSFWRHWHYMIOG-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 150000002989 phenols Chemical class 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920000515 polycarbonate Polymers 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920002689 polyvinyl acetate Polymers 0.000 description 2
- 239000011118 polyvinyl acetate Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- AQRYNYUOKMNDDV-UHFFFAOYSA-M silver behenate Chemical compound [Ag+].CCCCCCCCCCCCCCCCCCCCCC([O-])=O AQRYNYUOKMNDDV-UHFFFAOYSA-M 0.000 description 2
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 2
- 229910001923 silver oxide Inorganic materials 0.000 description 2
- UKHWJBVVWVYFEY-UHFFFAOYSA-M silver;hydroxide Chemical compound [OH-].[Ag+] UKHWJBVVWVYFEY-UHFFFAOYSA-M 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 125000002221 trityl group Chemical group [H]C1=C([H])C([H])=C([H])C([H])=C1C([*])(C1=C(C(=C(C(=C1[H])[H])[H])[H])[H])C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 238000004876 x-ray fluorescence Methods 0.000 description 2
- OMDQUFIYNPYJFM-XKDAHURESA-N (2r,3r,4s,5r,6s)-2-(hydroxymethyl)-6-[[(2r,3s,4r,5s,6r)-4,5,6-trihydroxy-3-[(2s,3s,4s,5s,6r)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxan-2-yl]methoxy]oxane-3,4,5-triol Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@@H]1OC[C@@H]1[C@@H](O[C@H]2[C@H]([C@@H](O)[C@H](O)[C@@H](CO)O2)O)[C@H](O)[C@H](O)[C@H](O)O1 OMDQUFIYNPYJFM-XKDAHURESA-N 0.000 description 1
- AFINAILKDBCXMX-PBHICJAKSA-N (2s,3r)-2-amino-3-hydroxy-n-(4-octylphenyl)butanamide Chemical compound CCCCCCCCC1=CC=C(NC(=O)[C@@H](N)[C@@H](C)O)C=C1 AFINAILKDBCXMX-PBHICJAKSA-N 0.000 description 1
- QGKMIGUHVLGJBR-UHFFFAOYSA-M (4z)-1-(3-methylbutyl)-4-[[1-(3-methylbutyl)quinolin-1-ium-4-yl]methylidene]quinoline;iodide Chemical compound [I-].C12=CC=CC=C2N(CCC(C)C)C=CC1=CC1=CC=[N+](CCC(C)C)C2=CC=CC=C12 QGKMIGUHVLGJBR-UHFFFAOYSA-M 0.000 description 1
- UXTZUUVTGMDXNG-UHFFFAOYSA-N 1,2-benzoxazine-3,4-dione Chemical compound C1=CC=C2C(=O)C(=O)NOC2=C1 UXTZUUVTGMDXNG-UHFFFAOYSA-N 0.000 description 1
- PUCYIVFXTPWJDD-UHFFFAOYSA-N 1,6-dihydroxycyclohexa-2,4-dienecarboxylic acid Chemical compound OC1C=CC=CC1(O)C(O)=O PUCYIVFXTPWJDD-UHFFFAOYSA-N 0.000 description 1
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 description 1
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- OEPOKWHJYJXUGD-UHFFFAOYSA-N 2-(3-phenylmethoxyphenyl)-1,3-thiazole-4-carbaldehyde Chemical compound O=CC1=CSC(C=2C=C(OCC=3C=CC=CC=3)C=CC=2)=N1 OEPOKWHJYJXUGD-UHFFFAOYSA-N 0.000 description 1
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- DFZVZKUDBIJAHK-UHFFFAOYSA-N 2-hydroxyoctadecanoic acid silver Chemical compound [Ag].OC(C(=O)O)CCCCCCCCCCCCCCCC DFZVZKUDBIJAHK-UHFFFAOYSA-N 0.000 description 1
- YQUVCSBJEUQKSH-UHFFFAOYSA-N 3,4-dihydroxybenzoic acid Chemical class OC(=O)C1=CC=C(O)C(O)=C1 YQUVCSBJEUQKSH-UHFFFAOYSA-N 0.000 description 1
- VPWNQTHUCYMVMZ-UHFFFAOYSA-N 4,4'-sulfonyldiphenol Chemical class C1=CC(O)=CC=C1S(=O)(=O)C1=CC=C(O)C=C1 VPWNQTHUCYMVMZ-UHFFFAOYSA-N 0.000 description 1
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- 125000003118 aryl group Chemical group 0.000 description 1
- CCGGDOVGIDSGQN-UHFFFAOYSA-N benzo[f][1,2]benzoxazine-1,2-dione Chemical compound C1=CC=CC2=C(C(C(=O)NO3)=O)C3=CC=C21 CCGGDOVGIDSGQN-UHFFFAOYSA-N 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
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- 235000019277 ethyl gallate Nutrition 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical group FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 1
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- 235000021588 free fatty acids Nutrition 0.000 description 1
- 235000004515 gallic acid Nutrition 0.000 description 1
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
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- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 150000002611 lead compounds Chemical class 0.000 description 1
- 229940100892 mercury compound Drugs 0.000 description 1
- 150000002731 mercury compounds Chemical class 0.000 description 1
- DZVCFNFOPIZQKX-LTHRDKTGSA-M merocyanine Chemical compound [Na+].O=C1N(CCCC)C(=O)N(CCCC)C(=O)C1=C\C=C\C=C/1N(CCCS([O-])(=O)=O)C2=CC=CC=C2O\1 DZVCFNFOPIZQKX-LTHRDKTGSA-M 0.000 description 1
- IBKQQKPQRYUGBJ-UHFFFAOYSA-N methyl gallate Natural products CC(=O)C1=CC(O)=C(O)C(O)=C1 IBKQQKPQRYUGBJ-UHFFFAOYSA-N 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- SNVLJLYUUXKWOJ-UHFFFAOYSA-N methylidenecarbene Chemical compound C=[C] SNVLJLYUUXKWOJ-UHFFFAOYSA-N 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000000025 natural resin Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 125000005543 phthalimide group Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 239000004584 polyacrylic acid Chemical class 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
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- 239000005056 polyisocyanate Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000473 propyl gallate Substances 0.000 description 1
- 235000010388 propyl gallate Nutrition 0.000 description 1
- 229940075579 propyl gallate Drugs 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000011669 selenium Substances 0.000 description 1
- 230000001235 sensitizing effect Effects 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- ZUNKMNLKJXRCDM-UHFFFAOYSA-N silver bromoiodide Chemical compound [Ag].IBr ZUNKMNLKJXRCDM-UHFFFAOYSA-N 0.000 description 1
- 229940045105 silver iodide Drugs 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- CLDWGXZGFUNWKB-UHFFFAOYSA-M silver;benzoate Chemical compound [Ag+].[O-]C(=O)C1=CC=CC=C1 CLDWGXZGFUNWKB-UHFFFAOYSA-M 0.000 description 1
- MNMYRUHURLPFQW-UHFFFAOYSA-M silver;dodecanoate Chemical compound [Ag+].CCCCCCCCCCCC([O-])=O MNMYRUHURLPFQW-UHFFFAOYSA-M 0.000 description 1
- ORYURPRSXLUCSS-UHFFFAOYSA-M silver;octadecanoate Chemical compound [Ag+].CCCCCCCCCCCCCCCCCC([O-])=O ORYURPRSXLUCSS-UHFFFAOYSA-M 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- RUQIYMSRQQCKIK-UHFFFAOYSA-M sodium;2,3-di(propan-2-yl)naphthalene-1-sulfonate Chemical compound [Na+].C1=CC=C2C(S([O-])(=O)=O)=C(C(C)C)C(C(C)C)=CC2=C1 RUQIYMSRQQCKIK-UHFFFAOYSA-M 0.000 description 1
- CVYDEWKUJFCYJO-UHFFFAOYSA-M sodium;docosanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCCCCCC([O-])=O CVYDEWKUJFCYJO-UHFFFAOYSA-M 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 125000005504 styryl group Chemical group 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 description 1
- 235000015523 tannic acid Nutrition 0.000 description 1
- 229940033123 tannic acid Drugs 0.000 description 1
- 229920002258 tannic acid Polymers 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 1
- 125000000101 thioether group Chemical group 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 238000003221 volumetric titration Methods 0.000 description 1
- 239000001993 wax Substances 0.000 description 1
- 239000001018 xanthene dye Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C1/00—Photosensitive materials
- G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
- G03C1/498—Photothermographic systems, e.g. dry silver
- G03C1/49809—Organic silver compounds
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C1/00—Photosensitive materials
- G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
- G03C1/498—Photothermographic systems, e.g. dry silver
- G03C1/4989—Photothermographic systems, e.g. dry silver characterised by a thermal imaging step, with or without exposure to light, e.g. with a thermal head, using a laser
Definitions
- the present invention relates to recording materials with improved shelf-life.
- Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy.
- Such recording materials become photothermographic upon incorporating a photosensitive agent which after exposure to UV, visible or IR light is capable of catalyzing or participating in a thermographic process bringing about changes in colour or optical density.
- GB-A 1,542,327 discloses a thermally developable light-sensitive sheet material, comprising a support and (a) a silver salt of an organic acid, (b) a catalyst in an amount capable of catalyzing the reaction in exposed areas of the material of components (a) and (c) after imagewise exposure and heating of the material, (c) a reducing agent for the salt (a), and (d) sulphur in an amount to reduce the colour change after processing and to reduce thermal fogging, the components (a) to (d) being contained, separately or together, in one or more layers coated on the support or being all present in the support or one or more of the components being present in the support and the remainder being in one or more layers coated thereon.
- GB 1,542,327 includes an exhaustive list of silver salts of an organic acid including silver palmitate. Furthermore, D.S. Avose, V.V. Tsvetkov and V.D. Yagodovskii in Sci. Appl. Photo. volume 35, pages 587-594 published in 1994 by Gordon and Breach Science Publishers S.A. describe the photothermographic materials based on silver bromide and silver palmitate.
- US 4,273,723 discloses a process for preparing a silver salt of a fatty acid with 12 to 24 carbon atoms consisting essentially of reacting an alkali metal salt of the fatty acid with a water-soluble silver salt, and wherein the reaction is effected in a reaction system consisting essentially of (I) the alkali metal salt of the fatty acid, (II) the water-soluble silver salt, (III) at least one water-soluble or partially water-soluble C 3 -C 8 alcohol and (IV) water, the volume ratio of the component (III) to the component (IV) being 1/5 to 5/1.
- GB-A 1,378,734 discloses a process of producing a silver salt of an organic carboxylic acid conducted in the presence of a soluble mercury compound and/or a soluble lead compound.
- EP-A 754 969 discloses a process for producing a suspension of particles containing a substantially light-insensitive silver salt of an organic carboxylic acid, comprising simultaneous metered addition of an aqueous solution or suspension of an organic carboxylic acid or its salt; and an aqueous solution of a silver salt to an aqueous liquid, wherein the metered addition of the aqueous solution or suspension of the organic carboxylic acid or its salt; and/or the aqueous solution of the silver salt is regulated by the concentration of silver ions or the concentration of anions of the silver salt in the aqueous liquid.
- Research Disclosure number 17029 published in June 1978,gives a survey of different methods of preparing organic heavy metal salts in section II.
- recording materials comprising a support and a thermosensitive element comprising silver palmitate with a higher crystallinity than prior art silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder exhibit a marked improvement in shelf-life over prior art recording materials with silver palmitate.
- a recording material comprising a support and a thermosensitive element comprising silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder, characterized in that the silver palmitate is not associated with mercury and/or lead ions and when the recording material is irradiated with a copper K ⁇ 1 X-ray source the ratio of the sum of the peak heights of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2 ⁇ , of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° to the sum of the peak heights of the X-ray diffraction lines at Bragg angles, 2 ⁇ , of 25.60°, 35.16° and 43.40° of NIST standard 1976, rhombohedral Al 2 O 3 , determined with the same X-ray diffractometer in the same state of adjustment on a sample of the recording material and a sample of the NIST standard 1976 cut to fit a
- a production process for a dispersion of particles of substantially light-insensitive organic silver salt including silver palmitate in a substantially solvent-free aqueous medium comprising the steps of: i) producing an aqueous dispersion of one or more organic acids including palmitic acid and an anionic surfactant; ii) substantially neutralizing the organic acids with aqueous alkali thereby forming organic acid salts including a palmitic acid salt; (iii) adding an aqueous solution of a silver salt to completely convert the organic acid salt(s) into their silver salts including silver palmitate, characterized in that the anionic surfactant is present in a molar ratio with respect to organic acid greater than 0.15 and the silver salt is added to produce organic silver salt(s) at a rate between 0.025mol/mol organic silver salt(s) • min and 2.25mol/mol organic silver salt(s) • min.
- Particles of substantially light-insensitive organic silver salt containing silver palmitate producible according to the above-mentioned process are also provided.
- a recording process is further provided according to the present invention comprising the steps of: (i) bringing an outermost layer of the above-mentioned recording material in proximity with a heat source; and (ii) applying heat from the heat source imagewise to the recording material while maintaining proximity to the heat source to produce an image; and (iii) removing the recording material from the heat source.
- the heat source is a thermal head with a thin film thermal head being particularly preferred.
- substantially light-insensitive is meant not intentionally light sensitive.
- substantially solvent-free aqueous medium is meant that solvent, if present, is present in amounts below 10% by volume of the aqueous medium.
- thermosensitive element comprises silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder.
- the element may comprise a layer system in which the ingredients may be dispersed in different layers, with the proviso that the two ingredients are in reactive association with one another i.e. during the thermal development process the reducing agent must be present in such a way that it is able to diffuse to the silver palmitate so that reduction of silver palmitate to silver can occur.
- thermosensitive element further comprises a photosensitive species capable upon exposure of forming a species capable of catalyzing reduction of the silver palmitate.
- the silver palmitate in the recording material, of the present invention is characterized in that when the recording material is irradiated with a copper K ⁇ 1 X-ray source the ratio of the sum of the peak heights of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2 ⁇ , of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° to the sum of the peak heights of the X-ray diffraction lines at Bragg angles, 2 ⁇ , of 25.60°, 35.16° and 43.40° of NIST (National Institute of Standards, Gaithersburg, MD 20899-0001, USA) standard 1976, rhombohedral Al 2 O 3 , determined with the same X-ray diffractometer in the same state of adjustment, divided by the square root of the quantity of silver in the recording material, expressed in g per m 2 , is greater than 3.09 m/g 0.5 , which is referred to in the detailed description of the present invention as
- the crystallinity of the silver palmitate in the recording material of the present invention is obtained by determining X-ray diffraction spectra on sheets of a particular recording material and of the NIST standard 1976 cut to fit the sample holder of the X-ray diffractometer used, subtracting the background using standard techniques, determining the peak heights (maxima) of the diffraction peaks, determining for the sample of recording material the sum of the peak heights (maxima), K material , of the XRD lines attributable to silver palmitate at Bragg angles, 2 ⁇ , of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° , determining for the sample of NIST standard 1976 the sum of the peak heights (maxima), K 1976 , of the X-ray diffraction lines at Bragg angles, 2 ⁇ , of 25.60°, 35.16° and 43.40°, calculating the ratio of K material /K 1976 for the recording material, determining the concentration of silver C Ag
- the concentration of silver present in the recording material can be determined by any known technique e.g. non-destructive methods such as X-ray fluorescence and destructive methods such as dissolution of the silver salt followed by standard volumetric techniques for the determination of silver, such as described in R. Belcher and A.J. Nutten, Quantitative Inorganic Analysis, 2nd Edition, Butterworths, London (1960), pages 201-219.
- non-destructive methods such as X-ray fluorescence
- destructive methods such as dissolution of the silver salt followed by standard volumetric techniques for the determination of silver, such as described in R. Belcher and A.J. Nutten, Quantitative Inorganic Analysis, 2nd Edition, Butterworths, London (1960), pages 201-219.
- Organic silver salt particles containing silver palmitate may contain up to 100mol% of silver palmitate. They preferably contain at least 50mol% of silver palmitate.
- Preferred substantially light-insensitive organic silver salts used in the present invention are silver salts of organic carboxylic acids for use in the recording materials of the present invention together with silver palmitate are silver salts of other aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms, e.g. silver laurate, silver stearate, silver hydroxystearate, silver behenate and silver arichidate.
- the silver palmitate of the present invention is not associated with mercury and/or lead ions. This means that mercury/and or silver ions are not intentionally added at any point during the preparation process and therefore are not intentionally associated with the silver palmitate in the recording material of the present invention.
- a production process for a dispersion of particles of substantially light-insensitive organic silver salt including silver palmitate in a substantially solvent-free aqueous medium comprising the steps of: i) producing an aqueous dispersion of one or more organic acids including palmitic acid and an anionic surfactant; ii) substantially neutralizing the organic acids with aqueous alkali thereby forming organic acid salts including a palmitic acid salt; (iii) adding an aqueous solution of a silver salt to completely convert the organic acid salts into their silver salts including silver palmitate, characterized in that the anionic surfactant is present in a molar ratio with respect to organic acid greater than 0.15 and the silver salt is added to produce organic silver salt(s) at a rate between 0.025mol/mol organic silver salt(s) • min and 2.25mol/mol organic silver salt(s) min.
- the anionic surfactant is present in a molar ratio with respect to organic carboxylic acid greater than 0.25 and the silver salt is added to produce organic silver salt(s) at a rate between 0.03mol/mol organic silver salt(s) min and 0.7mol/mol organic silver salt(s) • min, with a molar ratio of anionic surfactant with respect to organic acid greater than 0.3 and a rate of silver salt addition of between 0.04mol/mol organic silver salt(s) • min and 0.3mol/mol organic silver salt(s) • min being particularly preferred.
- step (iii) of the production process of the present invention is carried out such that part of the solution of acid salts produced in step (ii) of the process is present in the reaction vessel prior to silver salt solution addition and part thereof is added simultaneously with the addition of the silver salt solution, with about 25 to 50% of the solution of acid salts produced in step (ii) being in the reaction vessel prior to silver salt addition being particularly preferred.
- Preferred anionic surfactants for use in the above-mentioned process are alkali or ammonium salts of an acid selected from the group consisting of: alkylsulfonic acids, alkarylsulfonic acids, aralkylsulfonic acids, arylsulfonic acids, alkylsulfuric acids, aralkylsulfuric acids, arylsulfuric acids, alkarylsulfuric acids and organic carboxylic acids.
- Alkali or ammonium salts of alkylarylsulfonic acids are preferred with alkali or ammonium salts of alkylbenzene sulfonic acids being particularly preferred.
- Suitable anionic surfactants for use in the above-mentioned process are:
- the pH used is sufficiently low to avoid the oxidation of silver ions to silver oxide or silver hydroxide for which a pH below 10 is usually required
- the process temperature is chosen such that it is above the melting point of the organic acid(s) used, about 65°C in the case of palmitic acid, and the pocess is carried out with stirring, the stirring rate being dependent upon: the size of the stirrer relative to the reaction vessel, the type of stirrer used, avoidance of silver oxide or silver hydroxide formation due to insufficient mixing and avoidance of foaming, it usually being between 200 and 1000rpm.
- a slight excess of an organic acid for example 2mol% of palmitic acid, is preferred.
- the size of the substantially light-insensitive organic silver salt particles containing silver palmitate can be varied by varying the rate of silver salt addition, the concentration of anionic surfactant and the temperature, the equivalent diameter of the particles increasing with decreasing addition rate, decreasing anionic surfactant concentration and increasing temperature.
- the dispersion of particles of substantially light-insensitive organic silver salt containing silver palmitate is subjected to ultrafiltration.
- the ultrafiltration process removes ionic species and concentrates the dispersion of substantially light-insensitive organic silver salt containing silver palmitate by filtration through a cartridge-filter with a pore size sufficiently small to remove the salt produced upon the formation of the organic silver salt without removing the silver palmitate.
- Cartridge-filters with 10 000 to 500 000 MW have been found to be suitable for this purpose.
- the counterion of the anionic surfactant can be changed, if the presence of the original counterion be undesirable in the recording material.
- the sodium ions in Surfactant nr 1 can be replaced by ammonium ions by washing with an ammonium nitrate solution during the ultrafiltration process and the sodium ion concentration reduced to below 100ppm.
- the above-mentioned process produces substantially light-insensitive organic silver salt containing silver palmitate in which the silver palmitate has a crystallinity, as defined above, greater than 3.09 m/g 0.5 .
- recording materials can be produced, if dispersions thereof are produced using dispersion techniques in which the particles themselves are subjected to as little damage as possible commensurate with achieving a satisfactory dispersion quality e.g.using microfluidizers, ultrasonic apparatuses, rotor stator mixers etc.
- Suitable organic reducing agents for the reduction of organic silver salt particles containing silver palmitate are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with, aromatic di- and tri-hydroxy compounds.
- Catechol-type reducing agents i.e. reducing agents containing at least one benzene nucleus with two hydroxy groups (-OH) in ortho-position, such as catechol, 3-(3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, gallic acid and esters e.g.
- methyl gallate, ethyl gallate, propyl gallate, tannic acid, and 3,4-dihydroxy-benzoic acid esters are preferred, with those described in EP-B 692 733 and EP-A 903 625 being particularly preferred.
- Suitable reducing agents are sterically hindered phenols, bisphenols and sulfonamidophenols.
- Combinations of reducing agents may also be used that on heating become reactive partners in the reduction of the substantially light-insensitive organic silver salt comprising silver palmitate.
- combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents such as disclosed in US-P 5,464,738; trityl hydrazides and formyl-phenyl-hydrazides such as disclosed in US-P 5,496,695; trityl hydrazides and formyl-phenyl-hydrazides with diverse auxiliary reducing agents such as disclosed in US-P 5,545,505, US-P 5.545.507 and US-P 5,558,983; acrylonitrile compounds as disclosed in US-P 5,545,515 and US-P 5,635,339; and 2-substituted malonodialdehyde compounds as disclosed in US-P 5,654,130.
- thermosensitive element Film-forming binders of the thermosensitive element
- the film-forming binder of the thermosensitive element containing organic silver salt particles containing silver palmitate may be all kinds of natural, modified natural or synthetic resins or mixtures of such resins, in which the organic silver salt particles containing silver palmitate can be dispersed homogeneously either in aqueous or solvent media: e.g. cellulose derivatives such as ethylcellulose, cellulose esters, e.g.
- cellulose nitrate carboxymethylcellulose, starch ethers, galactomannan
- polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as polyvinyl chloride, after-chlorinated polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals that are made from polyvinyl alcohol as starting material in which only a part of the repeating vinyl alcohol units may have reacted with an aldehyde, preferably polyvinyl butyral, copolymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters, polystyrene and polyethylene or mixtures thereof.
- binders or mixtures thereof may be used in conjunction with waxes or "heat solvents” also called “thermal solvents” or “thermosolvents” improving the reaction speed of the redox-reaction at elevated temperature.
- thermosensitive element contains preferably in admixture with the organic silver salt particles containing silver palmitate and reducing agents a so-called toning agent known from thermography or photothermography.
- Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901 and those described in US-P 3,074,809, 3,446,648 and 3,844,797.
- Other particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type as disclosed in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
- stabilizers and antifoggants may be incorporated into the recording materials of the present invention.
- the recording material may contain in addition to the ingredients mentioned above other additives such as free fatty acids, surface-active agents, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, silicone oil, e.g. BAYSILONETM ⁇ l A (BAYER AG, GERMANY), ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments and/or optical brightening agents.
- antistatic agents e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
- silicone oil e.g. BAYSILONETM ⁇ l A (BAYER AG, GERMANY)
- ultraviolet light absorbing compounds e.g. BAYER AG, GERMANY
- the support for the thermosensitive element according to the present invention may be transparent, translucent or opaque, e.g. having a white light reflecting aspect and is preferably a thin flexible carrier e.g. polypropylene, polycarbonate or polyester, e.g. polyethylene terephthalate.
- a thin flexible carrier e.g. polypropylene, polycarbonate or polyester, e.g. polyethylene terephthalate.
- the support may be in sheet, ribbon or web form and subbed if need be to improve the adherence to the thereon coated thermosensitive element.
- the support may be made of an opacified resin composition. Should a transparent base be used, the base may be colourless or coloured, e.g. having a blue colour.
- One or more backing layers may be provided to control physical properties such as curl and static.
- the outermost layer of the recording material may in different embodiments of the present invention be the outermost layer of the thermosensitive element, a protective layer applied to the thermosensitive element or a layer on the opposite side of the support to the thermosensitive element.
- the thermosensitive element is provided with a protective layer to avoid local deformation of the thermosensitive element and to improve resistance against abrasion.
- the protective layer preferably comprises a binder, which may be solvent-soluble, solvent-dispersible, water-soluble or water-dispersible.
- a binder which may be solvent-soluble, solvent-dispersible, water-soluble or water-dispersible.
- solvent-soluble binders polycarbonates as described in EP-A 614 769 are particularly preferred.
- water-soluble or water-dispersible binders are preferred for the protective layer, as coating can be performed from an aqueous composition and mixing of the protective layer with the immediate underlayer can be avoided by using a solvent-soluble or solvent-dispersible binder in the immediate underlayer.
- a protective layer according to the present invention may comprise in addition a thermomeltable particle optionally with a lubricant present on top of the protective layer as described in WO 94/11199.
- a thermomeltable particle optionally with a lubricant present on top of the protective layer as described in WO 94/11199.
- at least one solid lubricant having a melting point below 150°C and at least one liquid lubricant in a binder is present, wherein at least one of the lubricants is a phosphoric acid derivative.
- the outermost layer according to the present invention may be crosslinked.
- Crosslinking can be achieved by using crosslinking agents such as described in WO 95/12495 for protective layers, e.g. tetra-alkoxysilanes, polyisocyanates, zirconates, titanates, melamine resins etc., with tetraalkoxysilanes such as tetramethylorthosilicate and tetraethylorthosilicate being preferred.
- the outermost layer of the recording material according to the present invention may comprise a matting agent.
- Suitable matting agents are described in WO 94/11198 and include e.g. talc particles and optionally protrude from the outermost layer.
- Solid or liquid lubricants or combinations thereof are suitable for improving the slip characteristics of the recording materials according to the present invention.
- Preferred solid lubricants are thermomeltable particles such as those described in WO 94/11199.
- a preferred photosensitive species capable upon exposure of forming species capable of catalyzing reduction of the silver palmitate of the present invention is silver halide.
- the photosensitive silver halide used in the present invention may be employed in a range of 0.1 to 100 mol percent; preferably, from 0.2 to 80 mol percent; particularly preferably from 0.3 to 50 mol percent; especially preferably from 0.5 to 35 mol %; and especially from 1 to 12 mol % of substantially light-insensitive organic silver salt.
- the silver halide may be any photosensitive silver halide such as silver bromide, silver iodide, silver chloride, silver bromoiodide, silver chlorobromoiodide, silver chlorobromide etc.
- the silver halide may be in any form which is photosensitive including, but not limited to, cubic, orthorhombic, tabular, tetrahedral, octagonal etc. and may have epitaxial growth of crystals thereon.
- the silver halide used in the present invention may be employed without modification. However, it may be chemically sensitized with a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc., a reducing agent such as a tin halide etc., or a combination thereof.
- a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc.
- a reducing agent such as a tin halide etc.
- thermosensitive element may contain an infra-red sensitizer, an ultra-violet light sensitizer or a visible light sensitizer.
- Suitable sensitizers include cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes.
- the thermosensitive element further includes a supersensitizer.
- the recording materials used in the present invention may also contain antihalation or acutance dyes which absorb light which has passed through the photosensitive thermally developable photographic material, thereby preventing its reflection.
- Such dyes may be incorporated into the photosensitive thermally developable photographic material or in any other layer of the photographic material of the present invention.
- any layer of the recording material of the present invention may proceed by any coating technique e.g. such as described in Modern Coating and Drying Technology, edited by Edward D. Cohen and Edgar B. Gutoff, (1992) VCH Publishers Inc. 220 East 23rd Street, Suite 909 New York, NY 10010, U.S.A.
- Thermographic imaging is carried out by the image-wise application of heat either in analogue fashion by direct exposure through an image of by reflection from an image, or in digital fashion pixel by pixel either by using an infra-red heat source, for example with a Nd-YAG laser or other infra-red laser, with a thermographic material preferably containing an infra-red absorbing compound, or by direct thermal imaging with a thermal head.
- an infra-red heat source for example with a Nd-YAG laser or other infra-red laser
- a thermographic material preferably containing an infra-red absorbing compound
- thermal printing image signals are converted into electric pulses and then through a driver circuit selectively transferred to a thermal printhead.
- the thermal printhead consists of microscopic heat resistor elements, which convert the electrical energy into heat via Joule effect.
- Such thermal printing heads may be used in contact or close proximity with the recording material.
- the operating temperature of common thermal printheads is in the range of 300 to 400°C and the heating time per picture element (pixel) may be less than 1.0ms, the pressure contact of the thermal printhead with the recording material being e.g. 200-500g/cm 2 to ensure a good transfer of heat.
- the image-wise heating of the recording material with the thermal printing heads may proceed through a contacting but removable resin sheet or web wherefrom during the heating no transfer of recording material can take place.
- Activation of the heating elements can be power-modulated or pulse-length modulated at constant power.
- the image-wise heating can be carried out such that heating elements not required to produce an image pixel generate an amount of heat (H e ) in accordance with the following formula: 0.5 H D ⁇ H e ⁇ H D wherein H D represents the minimum amount of heat required to cause visible image formation in the recording material.
- EP-A 654 355 discloses a method for making an image by image-wise heating by means of a thermal head having energizable heating elements, wherein the activation of the heating elements is executed duty cycled pulsewise.
- EP-A 622 217 discloses a method for making an image using a direct thermal imaging element producing improvements in continuous tone reproduction.
- Image-wise heating of the recording material can also be carried out using an electrically resistive ribbon incorporated into the material.
- Image- or pattern-wise heating of the recording material may also proceed by means of pixel-wise modulated ultra-sound.
- Photothermographic recording materials may be exposed with radiation of wavelength between an X-ray wavelength and a 5 microns wavelength with the image either being obtained by pixel-wise exposure with a finely focused light source, a UV, visible or IR wavelength laser or a light emitting diode or by direct exposure to the object itself or an image therefrom with appropriate illumination.
- any sort of heat source can be used that enables the recording materials to be uniformly heated to the development temperature in a time acceptable for the application concerned.
- Thermographic and photothermographic imaging can be used for the production of transparencies and reflection type prints.
- Application of the present invention is envisaged in the fields of both graphics images requiring high contrast images with a very steep dependence of print density upon applied dot energy and continuous tone images requiring a weaker dependence of print density upon applied dot energy, such as required in the medical diagnostic field.
- graphics images requiring high contrast images with a very steep dependence of print density upon applied dot energy
- continuous tone images requiring a weaker dependence of print density upon applied dot energy, such as required in the medical diagnostic field.
- black-imaged transparencies are widely used in inspection techniques operating with a light box.
- A was first prepared by adding 0.15 moles of solid sodium hydroxide to a dispersion of 0.1575 moles and 0.176 moles of palmitic acid respectively in 1L of deionized water at 68°C thereby producing a solution of sodium palmitate with a pH of ca. 9.
- Solution B 250mL of 0.6M aqueous silver nitrate acidified with 0.4g of 65% nitric acid at a temperature of 58°C, was then added with vigorous stirring to solution A in 15s while maintaining a temperature of 68°C. After 1 minute the resulting suspension of silver palmitate was cooled to room temperature and had a pH of ca. 5 and a UAg of ca. 350mV. The silver palmitate was filtered off under reduced pressure, washed twice each time with about 5L of deionized water and dried in a forced air drying cupboard at 40°C.
- the tone modifier dispersion was prepared by first dissolving 11g of K7598 in 69g of deionized water by first adding the gelatin, then allowing the gelatin to swell for 30 minutes and finally heating to 50°C. 20 g of T01 was added with ULTRA-TURRAXTM stirring to this gelatin solution at 50°C, and the stirring continued for a further 5 minutes. Finally the resulting dispersion was pumped through a DYNOMILLTM for 2 hours to produce the final tone modifier dispersion containing: 20% of T01 and 8.8% of gelatin.
- thermosensitive element thermosensitive element
- thermosensitive emulsion was produced as follows: 2.341g of K7598 was allowed to swell for 30 minutes with deionized water (for quantity used in the preparation of the thermographic emulsion for the particular recording material see table 2) and the resulting gel heated to 36°C, then with stirring the following ingredients were added: 5.699g of the tone modifier dispersion at 36°C, then 8.120g of LATEX 01 followed by 5 minutes stirring, the corresponding silver palmitate dispersion (for quantity and silver palmitate concentration therein for the thermosensitive emulsion for the particular recording material see table 2) followed by 5 minutes stirring, 12.35g of a 10.95% ethanol solution of R01 at 45°C and finally 2.880g of a 3.7% aqueous solution of formaldehyde.
- thermosensitive dispersions were doctor blade-coated onto a 175 ⁇ m subbed PET support and dried for 10 minutes at 50°C thereby producing the thermosensitive elements of COMPARATIVE EXAMPLES 1 & 2.
- the printer was equipped with a thin film thermal head with a resolution of 300 dpi and was operated with a line time of 19ms (the line time being the time needed for printing one line). During this line time the printhead received constant power.
- the average printing power being the total amount of electrical input energy during one line time divided by the line time and by the surface area of the heat-generating resistors, was 1.6 mJ/dot and was sufficient to obtain maximum optical density in each of the thermographic materials of COMPARATIVE EXAMPLES 1 & 2.
- the printhead was separated from the imaging layer by a thin intermediate material contacted with a slipping layer of a separable 5 ⁇ m thick polyethylene terephthalate ribbon coated successively with a subbing layer, heat-resistant layer and the slipping layer (anti-friction layer) giving a ribbon with a total thickness of 6 ⁇ m.
- the maximum densities, D max , and minimum densities, D min , of the prints given in table 3 were measured through a visible filter with a MACBETHTM TR924 densitometer in the grey scale steps corresponding to data levels of 64 and 0 respectively and are given in table 3 for COMPARATIVE EXAMPLES 1 & 2.
- a sodium palmitate solution was prepared by dissolving with stirring 24.5 g of sodium palmitate in a mixture of 80 mL of 2-propanol and 288 mL of deionized water at 70°C to give a 6.53% by weight solution.
- the silver palmitate synthesis was carried out at a constant UAg of 400mV as follows: to a stirred solution of 30g of K17881 in 1000mL of distilled water at 71°C in a double walled reactor, several drops of a 2.94M aqueous solution of silver nitrate were added to adjust the UAg at the start of the reaction to 400mV and then 340g of the above-mentioned sodium palmitate solution at a temperature of 75°C was metered into the reactor at a rate of 48mL/min and simultaneously a 3.792% by weight aqueous solution of silver nitrate was metered into the reactor, its addition rate being controlled by the quantity of the silver nitrate solution necessary to maintain a UAg of 400 ⁇ 5mV in the dispersing medium in the reactor.
- Both the sodium palmitate and silver nitrate solutions were added to the dispersing medium via small diameter tubes positioned just under the surface of the dispersing medium. By the end of the addition step 0.080moles of sodium behenate and 0.094 moles of silver nitrate had been added. The mixture was then stirred for a further 30 minutes. The resulting silver palmitate dispersion contained 1.63% by weight of silver behenate and 1.69% by weight of K17881.
- type III silver palmitate was carried out in the dark in a thermostatted stainless steel vessel with pH, pAg and temperature being continually monitored.
- the reagents were brought to the same temperature as the vessel prior to addition and were added at a known rate by a pumping system controlled by a computer with appropriate software.
- Palmitic acid was dissolved in ethanol at 65°C. 0.255N aqueous sodium hydroxide was added until the equivalence point was attained to obtain the sodium salt followed by a 0.401M aqueous solution of silver nitrate to complete conversion to form silver palmitate. The silver palmitate was then filtered off under reduced pressure, washed twice with deionized water and dried.
- 75g of dried type III silver palmitate was dispersed in 75g of a 10% aqueous solution of Surfactant Nr 1 by first producing a coarse suspension using an ULTRATURRAXTM and then dispersing the resulting coarse suspension in a MICROFLUIDICSTM M-110Y high pressure microfluidizer at a jet pressure of at 350 bar to produce the final dispersion with 20.173% silver palmitate.
- thermosensitive element thermosensitive element
- thermosensitive elements of the recording materials of INVENTION EXAMPLES 1 was produced as described for the thermosensitive element of the recording material of COMPARATIVE EXAMPLES 1 & 2 except that the quantity of deionized water, the silver palmitate type, concentration and quantity of dispersion used were as given in table 5 below.
- the recording materials of INVENTION EXAMPLE 1 only differs from those of COMPARATIVE EXAMPLES 1 & 2 in that they contain silver palmitate with an increased crystallinity. This demonstrates the beneficial effect of increased silver palmitate crystallinity on the stability of recording materials.
- Aqueous dispersions of the silver palmitate types IV & V were produced as follows:
- thermosensitive element thermosensitive element
- thermosensitive elements of the recording materials of INVENTION EXAMPLES 2 & 3 were produced as described for the thermosensitive element of the recording material of COMPARATIVE EXAMPLES 1 & 2 except that the quantity of deionized water used, the silver palmitate type, concentration and quantity of dispersion used were as given in table 9 below.
Description
- The present invention relates to recording materials with improved shelf-life.
- Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy. Such recording materials become photothermographic upon incorporating a photosensitive agent which after exposure to UV, visible or IR light is capable of catalyzing or participating in a thermographic process bringing about changes in colour or optical density.
- GB-A 1,542,327 discloses a thermally developable light-sensitive sheet material, comprising a support and (a) a silver salt of an organic acid, (b) a catalyst in an amount capable of catalyzing the reaction in exposed areas of the material of components (a) and (c) after imagewise exposure and heating of the material, (c) a reducing agent for the salt (a), and (d) sulphur in an amount to reduce the colour change after processing and to reduce thermal fogging, the components (a) to (d) being contained, separately or together, in one or more layers coated on the support or being all present in the support or one or more of the components being present in the support and the remainder being in one or more layers coated thereon. The description of GB 1,542,327 includes an exhaustive list of silver salts of an organic acid including silver palmitate. Furthermore, D.S. Avose, V.V. Tsvetkov and V.D. Yagodovskii in Sci. Appl. Photo. volume 35, pages 587-594 published in 1994 by Gordon and Breach Science Publishers S.A. describe the photothermographic materials based on silver bromide and silver palmitate.
- US 4,273,723 discloses a process for preparing a silver salt of a fatty acid with 12 to 24 carbon atoms consisting essentially of reacting an alkali metal salt of the fatty acid with a water-soluble silver salt, and wherein the reaction is effected in a reaction system consisting essentially of (I) the alkali metal salt of the fatty acid, (II) the water-soluble silver salt, (III) at least one water-soluble or partially water-soluble C3-C8 alcohol and (IV) water, the volume ratio of the component (III) to the component (IV) being 1/5 to 5/1.
- GB-A 1,378,734 discloses a process of producing a silver salt of an organic carboxylic acid conducted in the presence of a soluble mercury compound and/or a soluble lead compound. EP-A 754 969 discloses a process for producing a suspension of particles containing a substantially light-insensitive silver salt of an organic carboxylic acid, comprising simultaneous metered addition of an aqueous solution or suspension of an organic carboxylic acid or its salt; and an aqueous solution of a silver salt to an aqueous liquid, wherein the metered addition of the aqueous solution or suspension of the organic carboxylic acid or its salt; and/or the aqueous solution of the silver salt is regulated by the concentration of silver ions or the concentration of anions of the silver salt in the aqueous liquid. Research Disclosure number 17029, published in June 1978,gives a survey of different methods of preparing organic heavy metal salts in section II.
- The association of silver palmitate with mercury or lead ions, particularly mercury ions, according to the teaching of GB 1,378,734, is environmentally undesirable and infringes governmental regulations.
- Recording materials with prior art silver palmitate exhibit poor shelf-life, particularly as regards increase in Dmax.
- It is therefore an object of the invention to provide recording materials with an improved shelf-life.
- It is a still further object of the present invention to provide production processes for substantially light-insensitive organic silver salt comprising silver palmitate.
- Further objects and advantages of the invention will become apparent from the description hereinafter.
- Surprisingly it has been found that recording materials comprising a support and a thermosensitive element comprising silver palmitate with a higher crystallinity than prior art silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder exhibit a marked improvement in shelf-life over prior art recording materials with silver palmitate.
- The above mentioned objects are realised with a recording material comprising a support and a thermosensitive element comprising silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder, characterized in that the silver palmitate is not associated with mercury and/or lead ions and when the recording material is irradiated with a copper Kα1 X-ray source the ratio of the sum of the peak heights of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2Θ, of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° to the sum of the peak heights of the X-ray diffraction lines at Bragg angles, 2Θ, of 25.60°, 35.16° and 43.40° of NIST standard 1976, rhombohedral Al2O3, determined with the same X-ray diffractometer in the same state of adjustment on a sample of the recording material and a sample of the NIST standard 1976 cut to fit a sample holder of the X-ray diffractometer, divided by the square root of the quantity of silver in the recording material, expressed in g per m2, is greater than 3.09m/g0.5.
- A production process for a dispersion of particles of substantially light-insensitive organic silver salt including silver palmitate in a substantially solvent-free aqueous medium is also provided according to the present invention comprising the steps of: i) producing an aqueous dispersion of one or more organic acids including palmitic acid and an anionic surfactant; ii) substantially neutralizing the organic acids with aqueous alkali thereby forming organic acid salts including a palmitic acid salt; (iii) adding an aqueous solution of a silver salt to completely convert the organic acid salt(s) into their silver salts including silver palmitate, characterized in that the anionic surfactant is present in a molar ratio with respect to organic acid greater than 0.15 and the silver salt is added to produce organic silver salt(s) at a rate between 0.025mol/mol organic silver salt(s) • min and 2.25mol/mol organic silver salt(s) • min.
- Particles of substantially light-insensitive organic silver salt containing silver palmitate producible according to the above-mentioned process are also provided.
- A recording process is further provided according to the present invention comprising the steps of: (i) bringing an outermost layer of the above-mentioned recording material in proximity with a heat source; and (ii) applying heat from the heat source imagewise to the recording material while maintaining proximity to the heat source to produce an image; and (iii) removing the recording material from the heat source.
- Preferred embodiments of the invention are disclosed in the dependent claims.
- In a preferred embodiment of the recording process, according to the present invention, the heat source is a thermal head with a thin film thermal head being particularly preferred.
- By substantially light-insensitive is meant not intentionally light sensitive. By substantially solvent-free aqueous medium is meant that solvent, if present, is present in amounts below 10% by volume of the aqueous medium.
- The thermosensitive element, according to the present invention, comprises silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder. The element may comprise a layer system in which the ingredients may be dispersed in different layers, with the proviso that the two ingredients are in reactive association with one another i.e. during the thermal development process the reducing agent must be present in such a way that it is able to diffuse to the silver palmitate so that reduction of silver palmitate to silver can occur.
- In a preferred embodiment of the present invention the thermosensitive element further comprises a photosensitive species capable upon exposure of forming a species capable of catalyzing reduction of the silver palmitate.
- The silver palmitate in the recording material, of the present invention, is characterized in that when the recording material is irradiated with a copper Kα1 X-ray source the ratio of the sum of the peak heights of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2Θ, of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° to the sum of the peak heights of the X-ray diffraction lines at Bragg angles, 2Θ, of 25.60°, 35.16° and 43.40° of NIST (National Institute of Standards, Gaithersburg, MD 20899-0001, USA) standard 1976, rhombohedral Al2O3, determined with the same X-ray diffractometer in the same state of adjustment, divided by the square root of the quantity of silver in the recording material, expressed in g per m2, is greater than 3.09 m/g0.5, which is referred to in the detailed description of the present invention as the crystallinity of silver palmitate. In a preferred embodiment of the present invention, the crystallinity of silver palmitate is greater than 3.3 m/g0.5 and in a particularly preferred embodiment is greater than 3.8 m/g0.5.
- The crystallinity of the silver palmitate in the recording material of the present invention is obtained by determining X-ray diffraction spectra on sheets of a particular recording material and of the NIST standard 1976 cut to fit the sample holder of the X-ray diffractometer used, subtracting the background using standard techniques, determining the peak heights (maxima) of the diffraction peaks, determining for the sample of recording material the sum of the peak heights (maxima), Kmaterial, of the XRD lines attributable to silver palmitate at Bragg angles, 2Θ, of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° , determining for the sample of NIST standard 1976 the sum of the peak heights (maxima), K1976, of the X-ray diffraction lines at Bragg angles, 2Θ, of 25.60°, 35.16° and 43.40°, calculating the ratio of Kmaterial/K1976 for the recording material, determining the concentration of silver CAg present in the recording material in grams per square metre of material and finally normalizing the ratio Kmaterial/K1976 with √CAg to give Kmaterial/(K1976 x √Cag), which is a relative crystallinity for the silver palmitate in the recording material concerned. The exact positions of the peaks attributable to silver palmitate can vary within 0.3° of the angles given above. In such cases the peak height should be taken as the actual peak height of the peak and not the height of the peak at the angle given above.
- The concentration of silver present in the recording material can be determined by any known technique e.g. non-destructive methods such as X-ray fluorescence and destructive methods such as dissolution of the silver salt followed by standard volumetric techniques for the determination of silver, such as described in R. Belcher and A.J. Nutten, Quantitative Inorganic Analysis, 2nd Edition, Butterworths, London (1960), pages 201-219.
- Organic silver salt particles containing silver palmitate may contain up to 100mol% of silver palmitate. They preferably contain at least 50mol% of silver palmitate. Preferred substantially light-insensitive organic silver salts used in the present invention are silver salts of organic carboxylic acids for use in the recording materials of the present invention together with silver palmitate are silver salts of other aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms, e.g. silver laurate, silver stearate, silver hydroxystearate, silver behenate and silver arichidate. Silver salts of modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 and other organic silver salts as described in GB-P 1,439,478, e.g. silver benzoate, may likewise be used to produce a thermally developable silver image. Combinations of different organic silver salts may also be used in the present invention.
- The silver palmitate of the present invention is not associated with mercury and/or lead ions. This means that mercury/and or silver ions are not intentionally added at any point during the preparation process and therefore are not intentionally associated with the silver palmitate in the recording material of the present invention.
- A production process for a dispersion of particles of substantially light-insensitive organic silver salt including silver palmitate in a substantially solvent-free aqueous medium is provided according to the present invention comprising the steps of: i) producing an aqueous dispersion of one or more organic acids including palmitic acid and an anionic surfactant; ii) substantially neutralizing the organic acids with aqueous alkali thereby forming organic acid salts including a palmitic acid salt; (iii) adding an aqueous solution of a silver salt to completely convert the organic acid salts into their silver salts including silver palmitate, characterized in that the anionic surfactant is present in a molar ratio with respect to organic acid greater than 0.15 and the silver salt is added to produce organic silver salt(s) at a rate between 0.025mol/mol organic silver salt(s) • min and 2.25mol/mol organic silver salt(s) min. In preferred embodiments of the production process for a dispersion of particles of substantially light-insensitive organic silver salt including silver palmitate in a substantially solvent-free aqueous medium the anionic surfactant is present in a molar ratio with respect to organic carboxylic acid greater than 0.25 and the silver salt is added to produce organic silver salt(s) at a rate between 0.03mol/mol organic silver salt(s) min and 0.7mol/mol organic silver salt(s) • min, with a molar ratio of anionic surfactant with respect to organic acid greater than 0.3 and a rate of silver salt addition of between 0.04mol/mol organic silver salt(s) • min and 0.3mol/mol organic silver salt(s) • min being particularly preferred.
- In a preferred embodiment step (iii) of the production process of the present invention is carried out such that part of the solution of acid salts produced in step (ii) of the process is present in the reaction vessel prior to silver salt solution addition and part thereof is added simultaneously with the addition of the silver salt solution, with about 25 to 50% of the solution of acid salts produced in step (ii) being in the reaction vessel prior to silver salt addition being particularly preferred.
- Preferred anionic surfactants for use in the above-mentioned process are alkali or ammonium salts of an acid selected from the group consisting of: alkylsulfonic acids, alkarylsulfonic acids, aralkylsulfonic acids, arylsulfonic acids, alkylsulfuric acids, aralkylsulfuric acids, arylsulfuric acids, alkarylsulfuric acids and organic carboxylic acids. Alkali or ammonium salts of alkylarylsulfonic acids are preferred with alkali or ammonium salts of alkylbenzene sulfonic acids being particularly preferred. Suitable anionic surfactants for use in the above-mentioned process are:
- Surfactant Nr. 1 =
- MARLON™ A-396, a sodium alkyl-phenylsulfonate from Hüls;
- Surfactant Nr. 2=
- ERKANTOL™ BX, a sodium diisopropylnaphthalenesulfonate from BAYER;
- Surfactant Nr. 3 =
- ULTRAVON™ W, a sodium arylsulfonate from Ciba-Geigy;
- In the above-mentioned process the pH used is sufficiently low to avoid the oxidation of silver ions to silver oxide or silver hydroxide for which a pH below 10 is usually required, the process temperature is chosen such that it is above the melting point of the organic acid(s) used, about 65°C in the case of palmitic acid, and the pocess is carried out with stirring, the stirring rate being dependent upon: the size of the stirrer relative to the reaction vessel, the type of stirrer used, avoidance of silver oxide or silver hydroxide formation due to insufficient mixing and avoidance of foaming, it usually being between 200 and 1000rpm. Furthermore, a slight excess of an organic acid, for example 2mol% of palmitic acid, is preferred.
- The size of the substantially light-insensitive organic silver salt particles containing silver palmitate can be varied by varying the rate of silver salt addition, the concentration of anionic surfactant and the temperature, the equivalent diameter of the particles increasing with decreasing addition rate, decreasing anionic surfactant concentration and increasing temperature.
- In a further preferred embodiment of the above-mentioned process the dispersion of particles of substantially light-insensitive organic silver salt containing silver palmitate is subjected to ultrafiltration. The ultrafiltration process removes ionic species and concentrates the dispersion of substantially light-insensitive organic silver salt containing silver palmitate by filtration through a cartridge-filter with a pore size sufficiently small to remove the salt produced upon the formation of the organic silver salt without removing the silver palmitate. Cartridge-filters with 10 000 to 500 000 MW have been found to be suitable for this purpose. In order to maintain the stability of the dispersion of substantially light-insensitive organic silver salt containing silver palmitate during ultrafiltration it is necessary to maintain a minimum anionic surfactant concentration, but the counterion of the anionic surfactant can be changed, if the presence of the original counterion be undesirable in the recording material. For example the sodium ions in Surfactant nr 1 can be replaced by ammonium ions by washing with an ammonium nitrate solution during the ultrafiltration process and the sodium ion concentration reduced to below 100ppm.
- The above-mentioned process produces substantially light-insensitive organic silver salt containing silver palmitate in which the silver palmitate has a crystallinity, as defined above, greater than 3.09 m/g0.5.
- In the case of dried particles of organic silver salt containing silver palmitate with higher crystallinity, it has been found that recording materials, according to the present invention, can be produced, if dispersions thereof are produced using dispersion techniques in which the particles themselves are subjected to as little damage as possible commensurate with achieving a satisfactory dispersion quality e.g.using microfluidizers, ultrasonic apparatuses, rotor stator mixers etc.
- Suitable organic reducing agents for the reduction of organic silver salt particles containing silver palmitate are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with, aromatic di- and tri-hydroxy compounds. Catechol-type reducing agents, i.e. reducing agents containing at least one benzene nucleus with two hydroxy groups (-OH) in ortho-position, such as catechol, 3-(3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, gallic acid and esters e.g. methyl gallate, ethyl gallate, propyl gallate, tannic acid, and 3,4-dihydroxy-benzoic acid esters are preferred, with those described in EP-B 692 733 and EP-A 903 625 being particularly preferred.
- Other suitable reducing agents, particularly for photothermographic recording materials, are sterically hindered phenols, bisphenols and sulfonamidophenols.
- Combinations of reducing agents may also be used that on heating become reactive partners in the reduction of the substantially light-insensitive organic silver salt comprising silver palmitate. For example, combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents such as disclosed in US-P 5,464,738; trityl hydrazides and formyl-phenyl-hydrazides such as disclosed in US-P 5,496,695; trityl hydrazides and formyl-phenyl-hydrazides with diverse auxiliary reducing agents such as disclosed in US-P 5,545,505, US-P 5.545.507 and US-P 5,558,983; acrylonitrile compounds as disclosed in US-P 5,545,515 and US-P 5,635,339; and 2-substituted malonodialdehyde compounds as disclosed in US-P 5,654,130.
- The film-forming binder of the thermosensitive element containing organic silver salt particles containing silver palmitate may be all kinds of natural, modified natural or synthetic resins or mixtures of such resins, in which the organic silver salt particles containing silver palmitate can be dispersed homogeneously either in aqueous or solvent media: e.g. cellulose derivatives such as ethylcellulose, cellulose esters, e.g. cellulose nitrate, carboxymethylcellulose, starch ethers, galactomannan, polymers derived from α,β-ethylenically unsaturated compounds such as polyvinyl chloride, after-chlorinated polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals that are made from polyvinyl alcohol as starting material in which only a part of the repeating vinyl alcohol units may have reacted with an aldehyde, preferably polyvinyl butyral, copolymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters, polystyrene and polyethylene or mixtures thereof.
- The above mentioned binders or mixtures thereof may be used in conjunction with waxes or "heat solvents" also called "thermal solvents" or "thermosolvents" improving the reaction speed of the redox-reaction at elevated temperature.
- In order to obtain a neutral black image tone in the higher densities and neutral grey in the lower densities the thermosensitive element contains preferably in admixture with the organic silver salt particles containing silver palmitate and reducing agents a so-called toning agent known from thermography or photothermography.
- Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901 and those described in US-P 3,074,809, 3,446,648 and 3,844,797. Other particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type as disclosed in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
- In order to obtain improved shelf-life and reduced fogging, stabilizers and antifoggants may be incorporated into the recording materials of the present invention.
- The recording material may contain in addition to the ingredients mentioned above other additives such as free fatty acids, surface-active agents, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F3C(CF2)6CONH(CH2CH2O)-H, silicone oil, e.g. BAYSILONE™ Öl A (BAYER AG, GERMANY), ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments and/or optical brightening agents.
- The support for the thermosensitive element according to the present invention may be transparent, translucent or opaque, e.g. having a white light reflecting aspect and is preferably a thin flexible carrier e.g. polypropylene, polycarbonate or polyester, e.g. polyethylene terephthalate.
- The support may be in sheet, ribbon or web form and subbed if need be to improve the adherence to the thereon coated thermosensitive element. The support may be made of an opacified resin composition. Should a transparent base be used, the base may be colourless or coloured, e.g. having a blue colour. One or more backing layers may be provided to control physical properties such as curl and static.
- The outermost layer of the recording material may in different embodiments of the present invention be the outermost layer of the thermosensitive element, a protective layer applied to the thermosensitive element or a layer on the opposite side of the support to the thermosensitive element.
- According to a preferred embodiment of the recording material, according to the present invention, the thermosensitive element is provided with a protective layer to avoid local deformation of the thermosensitive element and to improve resistance against abrasion.
- The protective layer preferably comprises a binder, which may be solvent-soluble, solvent-dispersible, water-soluble or water-dispersible. Among the solvent-soluble binders polycarbonates as described in EP-A 614 769 are particularly preferred. However, water-soluble or water-dispersible binders are preferred for the protective layer, as coating can be performed from an aqueous composition and mixing of the protective layer with the immediate underlayer can be avoided by using a solvent-soluble or solvent-dispersible binder in the immediate underlayer.
- A protective layer according to the present invention may comprise in addition a thermomeltable particle optionally with a lubricant present on top of the protective layer as described in WO 94/11199. In a preferred embodiment at least one solid lubricant having a melting point below 150°C and at least one liquid lubricant in a binder is present, wherein at least one of the lubricants is a phosphoric acid derivative.
- The outermost layer according to the present invention may be crosslinked. Crosslinking can be achieved by using crosslinking agents such as described in WO 95/12495 for protective layers, e.g. tetra-alkoxysilanes, polyisocyanates, zirconates, titanates, melamine resins etc., with tetraalkoxysilanes such as tetramethylorthosilicate and tetraethylorthosilicate being preferred.
- The outermost layer of the recording material according to the present invention may comprise a matting agent. Suitable matting agents are described in WO 94/11198 and include e.g. talc particles and optionally protrude from the outermost layer.
- Solid or liquid lubricants or combinations thereof are suitable for improving the slip characteristics of the recording materials according to the present invention. Preferred solid lubricants are thermomeltable particles such as those described in WO 94/11199.
- A preferred photosensitive species capable upon exposure of forming species capable of catalyzing reduction of the silver palmitate of the present invention is silver halide.
- The photosensitive silver halide used in the present invention may be employed in a range of 0.1 to 100 mol percent; preferably, from 0.2 to 80 mol percent; particularly preferably from 0.3 to 50 mol percent; especially preferably from 0.5 to 35 mol %; and especially from 1 to 12 mol % of substantially light-insensitive organic silver salt.
- The silver halide may be any photosensitive silver halide such as silver bromide, silver iodide, silver chloride, silver bromoiodide, silver chlorobromoiodide, silver chlorobromide etc. The silver halide may be in any form which is photosensitive including, but not limited to, cubic, orthorhombic, tabular, tetrahedral, octagonal etc. and may have epitaxial growth of crystals thereon.
- The silver halide used in the present invention may be employed without modification. However, it may be chemically sensitized with a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc., a reducing agent such as a tin halide etc., or a combination thereof. The details of these procedures are described in T.H. James, "The Theory of the Photographic Process", Fourth Edition, Macmillan Publishing Co. Inc., New York (1977), Chapter 5, pages 149 to 169.
- The thermosensitive element, according to the present invention, may contain an infra-red sensitizer, an ultra-violet light sensitizer or a visible light sensitizer. Suitable sensitizers include cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes. According to the present invention the thermosensitive element further includes a supersensitizer.
- In addition to the ingredients, the recording materials used in the present invention may also contain antihalation or acutance dyes which absorb light which has passed through the photosensitive thermally developable photographic material, thereby preventing its reflection. Such dyes may be incorporated into the photosensitive thermally developable photographic material or in any other layer of the photographic material of the present invention.
- The coating of any layer of the recording material of the present invention may proceed by any coating technique e.g. such as described in Modern Coating and Drying Technology, edited by Edward D. Cohen and Edgar B. Gutoff, (1992) VCH Publishers Inc. 220 East 23rd Street, Suite 909 New York, NY 10010, U.S.A.
- Thermographic imaging is carried out by the image-wise application of heat either in analogue fashion by direct exposure through an image of by reflection from an image, or in digital fashion pixel by pixel either by using an infra-red heat source, for example with a Nd-YAG laser or other infra-red laser, with a thermographic material preferably containing an infra-red absorbing compound, or by direct thermal imaging with a thermal head.
- In thermal printing image signals are converted into electric pulses and then through a driver circuit selectively transferred to a thermal printhead. The thermal printhead consists of microscopic heat resistor elements, which convert the electrical energy into heat via Joule effect. Such thermal printing heads may be used in contact or close proximity with the recording material. The operating temperature of common thermal printheads is in the range of 300 to 400°C and the heating time per picture element (pixel) may be less than 1.0ms, the pressure contact of the thermal printhead with the recording material being e.g. 200-500g/cm2 to ensure a good transfer of heat.
- In order to avoid direct contact of the thermal printing heads with the outermost layer on the same side of the support as the thermosensitive element when this outermost layer is not a protective layer, the image-wise heating of the recording material with the thermal printing heads may proceed through a contacting but removable resin sheet or web wherefrom during the heating no transfer of recording material can take place.
- Activation of the heating elements can be power-modulated or pulse-length modulated at constant power. The image-wise heating can be carried out such that heating elements not required to produce an image pixel generate an amount of heat (He) in accordance with the following formula: 0.5 HD < He < HD wherein HD represents the minimum amount of heat required to cause visible image formation in the recording material.
- EP-A 654 355 discloses a method for making an image by image-wise heating by means of a thermal head having energizable heating elements, wherein the activation of the heating elements is executed duty cycled pulsewise. EP-A 622 217 discloses a method for making an image using a direct thermal imaging element producing improvements in continuous tone reproduction.
- Image-wise heating of the recording material can also be carried out using an electrically resistive ribbon incorporated into the material. Image- or pattern-wise heating of the recording material may also proceed by means of pixel-wise modulated ultra-sound.
- Photothermographic recording materials, according to the present invention, may be exposed with radiation of wavelength between an X-ray wavelength and a 5 microns wavelength with the image either being obtained by pixel-wise exposure with a finely focused light source, a UV, visible or IR wavelength laser or a light emitting diode or by direct exposure to the object itself or an image therefrom with appropriate illumination.
- For the thermal development of image-wise exposed photothermographic recording materials, according to the present invention, any sort of heat source can be used that enables the recording materials to be uniformly heated to the development temperature in a time acceptable for the application concerned.
- Thermographic and photothermographic imaging can be used for the production of transparencies and reflection type prints. Application of the present invention is envisaged in the fields of both graphics images requiring high contrast images with a very steep dependence of print density upon applied dot energy and continuous tone images requiring a weaker dependence of print density upon applied dot energy, such as required in the medical diagnostic field. In the hard copy field recording materials on a white opaque base are used, whereas in the medical diagnostic field black-imaged transparencies are widely used in inspection techniques operating with a light box.
- The invention is illustrated hereinafter by way of invention examples and comparative examples. The percentages and ratios given in these examples are by weight unless otherwise indicated. The ingredients used in the invention and comparative examples, other than those mentioned above, are:
- as organic silver salt:
- AgPa =
- silver palmitate;
- as binders:
- K7598 =
- type K7598, a calcium-free gelatin from AGFA-GEVAERT GELATINEFABRIEK vorm. KOEPFF & SÖHNE;
- K17881 =
- type K17881, a calcium-free gelatine from AGFA-GEVAERT GELATINEFABRIEK vorm. KOEPFF & SÖHNE;
- LATEX 01 =
- a 24% by weight aqueous latex of a polymer produced by copolymerizing a monomer mixture consisting of 42% by weight of n-butyl acrylate, 53% by weight of styrene, 2% by weight of itaconic acid and 3% by weight of CH2=C(CH3)CONH-(CH2)10-CONHC6H4-p-SO3K followed by desalting and adjusting to pH 5.4 with ammonia;
- as reducing agent:
- R01 =
- ethyl 3,4-dihydroxybenzoate;
- as toning agent:
- T01 =
- 7-(ethylcarbonato)-benzo[e][1,3]oxazine-2,4-dione (see formula I below)
- In the preparation of Types I & II silver palmitate solution, A was first prepared by adding 0.15 moles of solid sodium hydroxide to a dispersion of 0.1575 moles and 0.176 moles of palmitic acid respectively in 1L of deionized water at 68°C thereby producing a solution of sodium palmitate with a pH of ca. 9. Solution B, 250mL of 0.6M aqueous silver nitrate acidified with 0.4g of 65% nitric acid at a temperature of 58°C, was then added with vigorous stirring to solution A in 15s while maintaining a temperature of 68°C. After 1 minute the resulting suspension of silver palmitate was cooled to room temperature and had a pH of ca. 5 and a UAg of ca. 350mV. The silver palmitate was filtered off under reduced pressure, washed twice each time with about 5L of deionized water and dried in a forced air drying cupboard at 40°C.
- The quantities of type I and type II silver palmitates given in table 1 were dispersed with the quantities of deionized water, and 10% solution of Surfactant Nr 1 given in table 1 first with an ULTRATURRAX™ mixer to obtain a predispersion and then through a MICROFLUIDICS™ M-110Y high pressure microfluidizer at a jet pressure of 350 bar to produce the final dispersions with a concentration of 10.4%.
Comparative example nr silver palmitate quantity of deionized water g] quantity of 10% solution of Surfactant Nr 1 [g] type quantity [g] 1 I 54 346 100 2 II 58 342 100 - The tone modifier dispersion was prepared by first dissolving 11g of K7598 in 69g of deionized water by first adding the gelatin, then allowing the gelatin to swell for 30 minutes and finally heating to 50°C. 20 g of T01 was added with ULTRA-TURRAX™ stirring to this gelatin solution at 50°C, and the stirring continued for a further 5 minutes. Finally the resulting dispersion was pumped through a DYNOMILL™ for 2 hours to produce the final tone modifier dispersion containing: 20% of T01 and 8.8% of gelatin.
- The thermosensitive emulsion was produced as follows: 2.341g of K7598 was allowed to swell for 30 minutes with deionized water (for quantity used in the preparation of the thermographic emulsion for the particular recording material see table 2) and the resulting gel heated to 36°C, then with stirring the following ingredients were added: 5.699g of the tone modifier dispersion at 36°C, then 8.120g of LATEX 01 followed by 5 minutes stirring, the corresponding silver palmitate dispersion (for quantity and silver palmitate concentration therein for the thermosensitive emulsion for the particular recording material see table 2) followed by 5 minutes stirring, 12.35g of a 10.95% ethanol solution of R01 at 45°C and finally 2.880g of a 3.7% aqueous solution of formaldehyde.
- The thermosensitive dispersions were doctor blade-coated onto a 175µm subbed PET support and dried for 10 minutes at 50°C thereby producing the thermosensitive elements of COMPARATIVE EXAMPLES 1 & 2.
Comparative example number quantity of water [g] silver palmitate dispersion AgPa type concentration (%) quantity [g] 1 20.120 I 10.397 38.490 2 20.150 II 10.406 38.460 - The crystallinity of the silver palmitate in the recording materials of COMPARATIVE EXAMPLES 1 & 2 was determined as follows:
- i) 30mm diameter samples of the recording materials of COMPARATIVE EXAMPLES 1 & 2 and of NIST standard 1976 were cut from larger sheets using a punch;
- ii) X-ray diffraction scans were then carried out using a SIEMENS D5000 X-ray diffractometer equipped with a copper Kα1 X-ray source operating at 40keV and a current of 30mA with the samples in the sample holder thereof to scan the samples of COMPARATIVE EXAMPLES 1 & 2 and NIST standard 1976, with the same X-ray diffractometer in exactly the same state of adjustment, in steps of 0.05 degrees at a rate of 1 step/s between Bragg angles, 2Θ, of 2° and 50° and the data processed using SIEMENS DIFFRAC™ AT software to produce X-ray diffraction spectra corrected for background and exact peak heights (maxima) of each X-ray diffraction peak;
- iii) the Kmaterial values were then determined for the recording materials of COMPARATIVE EXAMPLES 1 & 2 by adding up the peak heights (maxima) of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2Θ, of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09°;
- iv) the K1976 value was determined for NIST standard 1976 by adding up the peak heights (maxima) of the X-ray diffraction lines at Bragg angles, 2Θ, of 25.60°, 35.16° and 43.40°;
- v) the weights of silver in g/m2, CAg, of the recording materials of COMPARATIVE EXAMPLES 1 & 2 were determined using a PHILIPS PW2400 wavelength dispersive X-ray fluorescence apparatus with a chromium Kα X-ray source operating at 60keV and a current of 50mA, which had been calibrated for silver using silver-containing samples for which the silver concentrations had been determined using standard volumetric titration techniques; and
- vi) the crystallinity values for the silver palmitate present in the recording materials of COMPARATIVE EXAMPLES 1 & 2 were determined using the expression: Kmaterial/(K1976 x √CAg). The crystallinity values for the silver palmitate in the recording materials of COMPARATIVE EXAMPLES 1 & 2 are given in Table 3.
-
- The printer was equipped with a thin film thermal head with a resolution of 300 dpi and was operated with a line time of 19ms (the line time being the time needed for printing one line). During this line time the printhead received constant power. The average printing power, being the total amount of electrical input energy during one line time divided by the line time and by the surface area of the heat-generating resistors, was 1.6 mJ/dot and was sufficient to obtain maximum optical density in each of the thermographic materials of COMPARATIVE EXAMPLES 1 & 2.
- During printing of the recording materials of COMPARATIVE EXAMPLES 1 & 2 the printhead was separated from the imaging layer by a thin intermediate material contacted with a slipping layer of a separable 5µm thick polyethylene terephthalate ribbon coated successively with a subbing layer, heat-resistant layer and the slipping layer (anti-friction layer) giving a ribbon with a total thickness of 6µm.
- The maximum densities, Dmax, and minimum densities, Dmin, of the prints given in table 3 were measured through a visible filter with a MACBETH™ TR924 densitometer in the grey scale steps corresponding to data levels of 64 and 0 respectively and are given in table 3 for COMPARATIVE EXAMPLES 1 & 2.
- The shelf-life of the recording materials of COMPARATIVE EXAMPLES 1 & 2 was evaluated on the basis of the changes in minimum and maximum density measured through a visible filter using a MACBETH™ TR924 densitometer upon thermographic printing after heating the recording materials at 57°C in a relative humidity of 34% for 3 days in the dark. The results are given in table 3.
Comparative example number Silver palmitate fresh print characteristics shelf-life
ΔDmax/ΔDmin (vis) after 3d at 57°C/34%RVtype coating weight [g/m2] crystallinity Dmax(vis) Dmin(vis) 1 I 3.40 2.45 3.41 0.07 +0.48/ +0.01 2 II 3.60 1.62 3.57 0.07 +0.33/ +0.01 - A sodium palmitate solution was prepared by dissolving with stirring 24.5 g of sodium palmitate in a mixture of 80 mL of 2-propanol and 288 mL of deionized water at 70°C to give a 6.53% by weight solution.
- The silver palmitate synthesis was carried out at a constant UAg of 400mV as follows: to a stirred solution of 30g of K17881 in 1000mL of distilled water at 71°C in a double walled reactor, several drops of a 2.94M aqueous solution of silver nitrate were added to adjust the UAg at the start of the reaction to 400mV and then 340g of the above-mentioned sodium palmitate solution at a temperature of 75°C was metered into the reactor at a rate of 48mL/min and simultaneously a 3.792% by weight aqueous solution of silver nitrate was metered into the reactor, its addition rate being controlled by the quantity of the silver nitrate solution necessary to maintain a UAg of 400±5mV in the dispersing medium in the reactor. Both the sodium palmitate and silver nitrate solutions were added to the dispersing medium via small diameter tubes positioned just under the surface of the dispersing medium. By the end of the addition step 0.080moles of sodium behenate and 0.094 moles of silver nitrate had been added. The mixture was then stirred for a further 30 minutes. The resulting silver palmitate dispersion contained 1.63% by weight of silver behenate and 1.69% by weight of K17881.
- 0.25g of K17881 was added per 100g of silver palmitate dispersion together with 6% of Surfactant Nr. 3 and the resulting dispersion doctor blade coated to a silver palmitate coverage of 3.23g/m2 after drying. The crystallinity of the silver palmitate in the resulting material was determined as described for COMPARATIVE EXAMPLES 1 & 2 to be 2.99, see table 4.
Comparative example number Silver palmitate type coating weight [g/m2] crystallinity 3 VI 3.23 2.99 - The synthesis of type III silver palmitate was carried out in the dark in a thermostatted stainless steel vessel with pH, pAg and temperature being continually monitored. The reagents were brought to the same temperature as the vessel prior to addition and were added at a known rate by a pumping system controlled by a computer with appropriate software.
- For the syntheses of silver palmitate the following programme settings were used:
- heating to 65°C;
- addition of a known quantity of a 0.255 mol/L solution of NaOH;
- addition of a known quantity of a 0.401 mol/L solution of AgNO3;
- all steps with pre and post washing.
- Palmitic acid was dissolved in ethanol at 65°C. 0.255N aqueous sodium hydroxide was added until the equivalence point was attained to obtain the sodium salt followed by a 0.401M aqueous solution of silver nitrate to complete conversion to form silver palmitate. The silver palmitate was then filtered off under reduced pressure, washed twice with deionized water and dried.
- 75g of dried type III silver palmitate was dispersed in 75g of a 10% aqueous solution of Surfactant Nr 1 by first producing a coarse suspension using an ULTRATURRAX™ and then dispersing the resulting coarse suspension in a MICROFLUIDICS™ M-110Y high pressure microfluidizer at a jet pressure of at 350 bar to produce the final dispersion with 20.173% silver palmitate.
- The thermosensitive elements of the recording materials of INVENTION EXAMPLES 1 was produced as described for the thermosensitive element of the recording material of COMPARATIVE EXAMPLES 1 & 2 except that the quantity of deionized water, the silver palmitate type, concentration and quantity of dispersion used were as given in table 5 below.
Invention example number quantity of water [g] silver palmitate dispersion AgPa type concentration (%) quantity [g] 1 18.18 III 20.17 19.810 - The crystallinity value for the silver palmitate present in the recording materials of INVENTION EXAMPLE 1 determined as described for COMPARATIVE EXAMPLES 1 & 2 is given in Table 6.
- Thermographic printing with the recording materials of INVENTION EXAMPLE 3 and the evaluation thereof were carried out as described for the recording materials of COMPARATIVE EXAMPLES 1 & 2. The evaluation results are summarized in Table 6.
Invention example number Silver palmitate fresh print characteristics shelf-life
ΔDmax/ΔDmin(vis) after 3d at 57°C/34%RVtype coating weight [g/m2] crystallinity Dmax (vis) Dmin (vis) 1 III 3.40 3.10 3.51 0.07 +0.23/+0.01 - Aqueous dispersions of the silver palmitate types IV & V were produced as follows:
- i) dispersing palmitic acid (for quantity see table 7) with stirring at a given temperature (see table 7) in a mixture of deionized water (for quantity see table 7) and a 10% solution of Surfactant Nr 1 (for quantity see table 3) to produce a dispersion with a pH of about 4.2;
- ii) then adding a quantity of sodium hydroxide as a 2M aqueous solution (for quantity see table 7) at the same temperature as the palmitic acid dispersion with stirring over a particular time (see table 7 for the time of addition) thereby producing a clear solution with a pH of about 9.2 substantially containing sodium palmitate;
- iii) then metered addition of a particular quantity of silver nitrate (same quantity in moles as for sodium hydroxide) as a 1M aqueous solution at the same temperature as the palmitic acid dispersion with stirring at a particular rate (for rate given as moles/moles silver palmitate • min see table 7) to convert the sodium palmitate completely into silver palmitate as a dispersion with a pH and UAg as given in table 7; and
- iv) ultrafiltration with a 500000 MW polysulfone cartridge filter at room temperature to concentrate the resulting silver palmitate dispersion (final AgPa-concentration and residual conductivity in mS/cm are given in table 8). The volume average particle size as determined by a Coulter LS230 diffractometer is also given in table 8.
-
- These dispersions of silver palmitate were directly used in the preparation of the recording materials of INVENTION EXAMPLES 2 & 3.
- The thermosensitive elements of the recording materials of INVENTION EXAMPLES 2 & 3 were produced as described for the thermosensitive element of the recording material of COMPARATIVE EXAMPLES 1 & 2 except that the quantity of deionized water used, the silver palmitate type, concentration and quantity of dispersion used were as given in table 9 below.
Invention example number quantity of water [g] silver palmitate dispersion AgPa type concentration (%) quantity [g] 2 13.397 IV 15.85 25.213 3 12.820 V 15.49 25.790 - The crystallinity values for the silver palmitate present in the recording materials of INVENTION EXAMPLES 2 & 3 determined as described for COMPARATIVE EXAMPLES 1 & 2 are given in Table 10.
- Thermographic printing with the recording materials of INVENTION EXAMPLES 2 & 3 and the evaluation thereof were carried out as described for the recording material of COMPARATIVE EXAMPLES 1 & 2. The evaluation results are summarized in Table 10.
- These results show a considerable improvement in the shelf-life of recording materials of INVENTION EXAMPLES 2 & 3 compared with the recording materials of COMPARATIVE EXAMPLES 1 & 2 using prior art silver palmitate as demonstrated by a reduced increase in Dmax while maintaining Dmin-stability. The recording materials of INVENTION EXAMPLES 2 & 3 only differ from those of COMPARATIVE EXAMPLES 1 & 2 in that they contain silver palmitate with an increased crystallinity. This demonstrates the beneficial effect of increased silver palmitate crystallinity on the stability of recording materials.
Invention example number Silver palmitate fresh print characteristics shelf-life
ΔDmax/ΔDmin (vis) after 3d at 57°C/34%RVtype coating weight [g/m2] crystallinity Dmax (vis) Dmin (vis) 2 IV 3.17 5.81 3.16 0.07 -0.17/+0.01 3 V 2.90 3.99 3.04 0.08 +0.08/0.00 - Having described in detail preferred embodiments of the current invention, it will now be apparent to those skilled in the art that. numerous modifications can be made therein without departing from the scope of the invention as defined in the following claims.
Invent ion example nr | AgPa type | quantity of palmitic acid [moles] | quantity of deionized water [L] | quantity of 10% sol. of Surfactant Nr 1 [L] | temperature [°C] | quantity of NaOH & AgNO3 [moles] | addition time of 2M NaOH [min] | mol AgNO3/mol AgPa • min | pH | UAg [mV] |
2 | IV | 1.507 | 2.495 | 2.027 | 63 | 1.477 | 9.75 | 0.0650 | 6.40 | +320 |
3 | V | 0.4 | 0.662 | 0.538 | 63 | 0.392 | 10 | 0.25 | 5.76 | +405 |
Invention example nr | AgPa type | ultrafiltration | average particle size [nm] | |
residual conductivity [mS/cm] | % AgPa dispersion | |||
2 | IV | 3.4 | 15.85 | 725 |
3 | V | 3.45 | 15.52 |
Claims (11)
- A recording material comprising a support and a thermosensitive element comprising silver palmitate, an organic reducing agent therefor in thermal working relationship therewith and a binder, characterized in that said silver palmitate is not associated with mercury and/or lead ions and when said recording material is irradiated with a copper Kα1 X-ray source the ratio of the sum of the peak heights of the X-ray diffraction lines attributable to silver palmitate at Bragg angles, 2Θ, of 4.01°, 6.049°, 8.031°, 10.06°, 12.08° and 14.09° to the sum of the peak heights of the X-ray diffraction lines at Bragg angles, 2Θ, of 25.60°, 35.16° and 43.40° of NIST standard 1976, rhombohedral Al2O3, determined with the same X-ray diffractometer in the same state of adjustment on a sample of said recording material and a sample of said NIST standard 1976 cut to fit a sample holder of said X-ray diffractometer, divided by the square root of the quantity of silver in the recording material, expressed in g per m2, is greater than 3.09m/g0.5.
- Recording material according to claim 1, wherein said ratio, divided by the square root of the quantity of silver in the recording material expressed in g per m2 is greater than 3.3m/g0.5.
- Recording material according to any of the preceding claims, wherein said thermosensitive element is provided with a protective layer.
- Recording material according to any of the preceding claims, wherein said thermosensitive element further comprises a photosensitive species capable upon exposure of forming a species capable of catalyzing reduction of said silver palmitate.
- A production process for a dispersion of particles of substantially light-insensitive organic silver salt containing silver palmitate in a substantially solvent-free aqueous medium comprising the steps of: i) producing an aqueous dispersion of one or more organic acids including palmitic acid and an anionic surfactant; ii) substantially neutralizing said organic acids with aqueous alkali thereby forming organic acid salts including a palmitic acid salt; (iii) adding an aqueous solution of a silver salt to completely convert said organic acid salts into their silver salts including silver palmitate, characterized in that said anionic surfactant is present in a molar ratio with respect to organic acid greater than 0.15 and said silver salt is added to produce organic silver salt(s) at a rate between 0.025mol/mol organic silver salt(s) • min and 2.25mol/mol organic silver salt(s) • min.
- Production process according to claim 5, wherein said anionic surfactant is an alkali or ammonium salt of an alkaryl sulfonic acid.
- Production process according to claim 6, wherein said alkali or ammonium salt of an alkaryl sulfonic acid is an alkali or ammonium salt of an alkylbenzene sulfonic acid.
- Production process according to any of claims 5 to 7 further comprising the step of subjecting said dispersion of particles of substantially light-insensitive organic silver salt(s) containing silver palmitate to ultrafiltration.
- Particles of substantially light-insensitive organic silver salt containing silver palmitate producible according to any of claims 5 to 8.
- A recording process comprising the steps of: (i) bringing an outermost layer of a recording material according to any of claims 1 to 3 into proximity with a heat source; and (ii) applying heat from said heat source imagewise to said recording material while maintaining proximity to said heat source to produce an image; and (iii) removing said recording material from said heat source.
- Recording process according to claim 10, wherein said heat source is a thin film thermal head.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19990201712 EP0962815B1 (en) | 1998-06-06 | 1999-05-25 | Recording material with improved image tone and/or stability upon thermal development |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98201961 | 1998-06-06 | ||
EP98201961 | 1998-06-06 | ||
EP19990201712 EP0962815B1 (en) | 1998-06-06 | 1999-05-25 | Recording material with improved image tone and/or stability upon thermal development |
Publications (2)
Publication Number | Publication Date |
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EP0962815A1 EP0962815A1 (en) | 1999-12-08 |
EP0962815B1 true EP0962815B1 (en) | 2003-01-15 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP19990201712 Expired - Lifetime EP0962815B1 (en) | 1998-06-06 | 1999-05-25 | Recording material with improved image tone and/or stability upon thermal development |
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EP (1) | EP0962815B1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001188313A (en) * | 1999-10-20 | 2001-07-10 | Fuji Photo Film Co Ltd | Method for producing silver salt of organic acid and heat developable photosensitive material using same |
US6391537B2 (en) * | 2000-02-10 | 2002-05-21 | Eastman Kodak Company | Polyacrylamide surface modifiers for silver carboxylate nanoparticles |
US6355408B1 (en) | 2000-05-04 | 2002-03-12 | Eastman Kodak Company | Core-shell silver salts and imaging compositions, materials and methods using same |
US6472131B1 (en) | 2000-05-04 | 2002-10-29 | Eastman Kodak Company | Asymmetric silver salt dimers and imaging compositions, materials and methods using same |
US6803177B2 (en) | 2002-07-30 | 2004-10-12 | Eastman Kodak Company | Silver compounds and compositions, thermally developable materials containing same, and methods of preparation |
Family Cites Families (2)
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DE69621337T2 (en) * | 1995-07-18 | 2002-11-21 | Agfa Gevaert Nv | PHOTOTHERMOGRAPHIC RECORDING MATERIAL |
EP0848286B1 (en) * | 1996-12-10 | 2005-04-06 | Agfa-Gevaert | Thermographic recording material with improved image tone and/or stability upon thermal development |
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1999
- 1999-05-25 EP EP19990201712 patent/EP0962815B1/en not_active Expired - Lifetime
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