Curable organopolysiloxane release agent composition for thermal paper, thermal paper, and thermal recording label sheet

Abstract

Provided is a curable organopolysiloxane releasing agent composition for a thermally sensitive paper wherein a releasing layer that has high adhesion and a good peeling force that is cured quickly at a low temperature without producing curing failures when coated on a thermally sensitive coloring layer, and that is resistant to gellification at room temperature, and that has superior ease of handling, can be formed. The curable organopolysiloxane releasing agent composition comprises: (A) one or more organopolysiloxanes having an alkenyl group with a number of carbon atoms between 4 and 12, where the inclusion proportion of vinyl (CH.sub.2?CH) within the alkenyl group is between 0.5 and 3.0 mass %; (B) an organohydrogen polysiloxane having at least two silicon-bonded hydrogen atoms (SiH) in a single molecule; (C) a hydrosilylation reaction catalyst; and (D) a hydrosilylation reaction inhibiting agent.

Claims

1. A curable organopolysiloxane releasing agent composition for a thermally sensitive paper, said composition comprising the following components: (A) one or more organopolysiloxanes having an alkenyl group with a number of carbon atoms between 4 and 12, where the inclusion proportion of vinyl (CH.sub.2?CH) within the alkenyl group is between 0.5 and 3.0 mass %; (B) an organohydrogen polysiloxane mixture of two or more different organohydrogen polysiloxanes each having at least two silicon-bonded hydrogen atoms (SiH) in a single molecule, wherein the component (B) comprises: (B1) an organohydrogen polysiloxane having a viscosity at 25? C. in a range of from 2.5 to 50 mPa.Math.s; and (B2) an organohydrogen polysiloxane having a viscosity at 25? C. in a range of from 100 to 500 mPa.Math.s; wherein the components (B1) and (B2) are mixed with a mass ratio of from 75:25 to 90:10, and wherein the component (B1) has a lower degree of polymerization than the component (B2); (C) a hydrosilylation reaction catalyst; and (D) a hydrosilylation reaction inhibiting agent; wherein the silicon atom-bonded hydrogen atoms within the component (B) is in an amount of from 1.0 to 4.0 moles per one mole of carbon-carbon double bonds in in the component (A), and wherein the curable organopolysiloxane releasing agent composition is solvent-free.

2. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the silicon atom-bonded hydrogen atoms within the component (B) is in an amount of from 1.5 and 3.0 moles per one mole of carbon-carbon double bonds in component (A).

3. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein: the component (A) is an organopolysiloxane that includes a hexenyl group as the alkenyl group with the number of carbon atoms between 4 and 12; and the inclusion proportion, in the composition, of organopolysiloxanes having alkenyl groups with a number of carbon atoms less than 4 is no more than 5.0 mass % of the component (A).

4. The curable organopolysiloxane releasing agent composition as set forth in claim 1, further comprising: (E) a photopolymerization initiator.

5. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the viscosity of the composition at 25? C. is between 100 and 50,000 mPa.Math.s.

6. A thermally sensitive paper having a releasing layer that is produced through curing the curable organopolysiloxane releasing agent composition as set forth in claim 1.

7. The thermally sensitive paper as set forth in claim 6, wherein the releasing layer is formed on a thermally sensitive coloring layer or on an intermediate layer that is formed on a thermally sensitive coloring layer.

8. A thermally sensitive printing label sheet that includes the thermally sensitive paper as set forth in claim 6.

9. A linerless thermally sensitive printing label sheet having a structure that includes the thermally sensitive paper as set forth in claim 6, wherein an adhesive layer faces the releasing layer on the thermally sensitive paper.

10. A method for manufacturing a thermally sensitive paper, or a label including a thermally sensitive paper, said method comprising: coating the curable organopolysiloxane releasing agent composition as set forth in claim 1 onto a substrate that comprises a thermally sensitive coloring layer; and curing, at a temperature that substantially does not cause color development or discoloration of the thermally sensitive coloring layer, the curable organopolysiloxane releasing agent composition on the substrate to form a releasing layer.

11. A method for manufacturing a thermally sensitive paper, or a label that includes a thermally sensitive paper, said method comprising: coating the curable organopolysiloxane releasing agent composition as set forth in claim 5 onto a substrate that comprises a thermally sensitive coloring layer; and curing, through a combination of heating and an energy beam, the curable organopolysiloxane releasing agent composition to form a releasing agent on the substrate.

12. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the inclusion proportion of vinyl (CH.sub.2?CH) within the alkenyl group of the component (A) is between 1 and 2 mass %.

13. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the component (A) has a viscosity at 25? C. between 50 and 1,000 mPa.Math.s.

14. The curable organopolysiloxane releasing agent composition as set forth in claim 13, wherein the component (A) has a viscosity at 25? C. between 100 and 500 mPa.Math.s.

15. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the component (D) is included in an amount of between 0.001 and 5 parts by weight per 100 parts by weight of the component (A).

16. The curable organopolysiloxane releasing agent composition as set forth in claim 3, wherein the component (D) is included in an amount of between 0.001 and 5 parts by weight per 100 parts by weight of the component (A).

17. The curable organopolysiloxane releasing agent composition as set forth in claim 5, wherein the viscosity of the composition at 25? C. is between 100 and 20,000 mPa.Math.s.

18. The curable organopolysiloxane releasing agent composition as set forth in claim 1, wherein the components (B1) and (B2) are mixed with a mass ratio of from 75:25 to 85:15.

Description

EMBODIMENTS

(1) The present invention will be explained in greater detail below through presenting embodiments of the present invention along with reference examples; however, the present invention is not limited to the embodiments set forth below. Moreover, in the examples below, parts that indicate quantities mean parts by weight. Moreover, a vinyl (CH.sub.2?CH) part indicates a vinyl (CH.sub.2?CH) group part that is a site that includes a carbon-carbon double bond in an alkenyl group that is bonded to a silicon atom, where the inclusion proportion of the vinyl part occupied in the total weight of the molecule indicates a mass %, and when the alkenyl group is a vinyl group, means simply the vinyl group inclusion proportion. Viscosity is a value that is measured at 25? C. The method for measuring plasticity is as described above, and the viscosity measurement is carried out using a Digital Display B-type rotary viscometer (Vismetron VDA2, manufactured by Toshiba Systems Corporation). Moreover, the releasing resistance value (peeling force) of the layer of the cured material made from the curable organopolysiloxane composition is measured through the method presented below.

(2) [Method for Forming the Cured Layer]

(3) A printing suitability tester (RI-2, Tester Sangyo Co., Ltd.) was used to coat the curable organopolysiloxane composition in an amount that would produce 1.00 g/m.sup.2, as a solid content equivalent value, onto the surface of a commercially available thermally sensitive paper (Thermal Paper 135LA-1, manufactured by Ricoh Co., Ltd.). After coating, the substrate on which the composition set forth above had been coated was subjected to a heating process under the conditions shown in the various tables in a hot air circulation-type oven, or exposed to ultraviolet radiation after heating, to form a cured layer of an organopolysiloxane on the thermally sensitive paper surface.

(4) [Evaluation of Cureability]

(5) Each composition was coated onto the same commercially available thermally sensitive paper described above (Thermal Paper 135LA-1, manufactured by Ricoh Co., Ltd.) using the printing suitability tester (RI-2, Tester Sangyo Co., Ltd.), and subjected to a heating process for 30 seconds at various temperatures of 80? C., 90? C., 100? C., and 110? C., and, for Embodiment 2, was further subjected to exposure to ultraviolet radiation, after which the forms of the various cured layer coatings were evaluated by strongly rubbing the coating surface with a finger five times (5 reciprocations), and evaluating visually whether or not there is clouding (smearing) using the reference below: ?: No clouding (smearing) visible on the coated surface even after rubbing the coated surface with a finger ?: Slight clouding (smearing) found on the coated surface after rubbing the coated surface with the finger x: Clouding (smearing) found on the coated surface after rubbing the coated surface with the finger
[Pot Life: Usable Time Period at 40? C.]

(6) Each composition, after mixing, was stored at 40? C., to measure the time until gellification of the entire composition. If the composition was not gellified after four hours, the evaluation was a ?, as the usable time period being adequate for practical use, where if the time until gellification of the composition was one hour or less, than the evaluation was x, as the usable time period being inadequate.

(7) [Peeling Force Evaluation: Initial Peeling Force (One-Day Curing) and Time-Elapsed Peeling Force (One-Week Curing)]

(8) The solvent-free releasable cured coated formable silicon composition of the embodiments and reference examples were coated in an amount to produce a 1.0 g/m.sup.2 siloxane equivalent onto a commercially available thermally sensitive paper (Thermal Paper 135LA-1, manufactured by Ricoh Co., Ltd.) using a printing suitability tester (Tester Sangyo Co., Ltd., RI-2) followed by curing for 30 seconds at 100? C. to produce the cured coating. After this was further cured for one day under 25? C., 60% humidity conditions, an applicator was used to coat the cured coating surface uniformly with an acrylic emulsion-type adhesive agent (brand name: Olivine BPW6116A, manufactured by Toyo Ink Co., Ltd.) to have a wet thickness of 100 ?m, followed by drying for two minutes at 100? C. This was followed by layering a layered paper thereon, and applying a load up 20 g/cm.sup.2 thereto, and storing for one day under conditions of 25? C. with a humidity of 60%. Following this, the result of measuring the peeling force when pulling the layered paper, using a pull tester, in 180? directions at a speed of 0.3 m/min was evaluated as the initial peeling force.

(9) On the other hand, a cured coating was produced in the same manner as described above, and after curing for another week under conditions of 25? C. and a humidity of 60%, the result of measuring the peeling force using the pull tester in the same manner as described above was evaluated as the time-elapsed peeling force. Note that the sample widths were 5 cm for all, and no measurement of peeling force was carried out when the evaluation was a curing failure in the peelability evaluation, described above.

(10) [Surface Color Development Evaluation of the Thermally Sensitive Paper]

(11) The curable organopolysiloxane compositions described above were coated onto the surface of a commercially available thermally sensitive paper (Thermal Paper 135LA-1, manufactured by Ricoh Co., Ltd.), followed by heating for a prescribed time (30 seconds) under various curing conditions, followed by evaluating whether or not there was color development of the thermally sensitive paper, using the standards below: Color Development Absent (?): No color development was observed in the thermally sensitive paper after heating (white). Color Development Present (?): Slight blackening of the thermally sensitive paper surface after heating, with the white paper becoming gray.

(12) Note that, for both the compositions used in the examples and in the reference embodiments, the results were dependent only on the heating temperature and heating time of the thermally sensitive paper, and are thus shown together on the left side of Table 1. In these test conditions, discoloration of the thermally sensitive paper occur in heating at 110? C. for 30 seconds, and thus these conditions are undesirable as curing conditions.

(13) [Evaluation of Adhesion of Releasing Layer]

(14) Similar to the evaluation of the curability, described above, the cured layers of organopolysiloxane (=releasing layers) were formed on thermally sensitive paper surfaces, and, for the various conditions shown in Table 2, the adhesion of the releasing layers to the thermally sensitive papers were evaluated. The adhesion was evaluated by rubbing the coating surface strongly with a finger five times (five reciprocations) and evaluating whether or not the coating came off (rubbed off).

(15) ?: The releasing layer did not come off from the thermally sensitive paper.

(16) ?: Some slight occurrence of the releasing layer coming off from the thermally sensitive paper.

(17) x: The releasing layer came off the thermally sensitive paper.

[Embodiment 1] Composition 1

(18) A curable organopolysiloxane composition was produced through uniformly mixing: (A) 93.76 parts of a polydimethyl sulfoxide having hexenyl groups on both ends of the molecular chain and on a side chain (viscosity of 200 mPa.Math.s, with the inclusion proportion for the vinyl (CH.sub.2?CH) part in the hexenyl groups being 1.15 mass %), (B1-1) 3.00 parts dimethyl methylhydrogen polysiloxane blocked with trimethyl siloxy groups on both ends of the molecular chain, with a viscosity of 25 mPa.Math.s, (B1-2) 3.00 parts dimethyl methylhydrogen polysiloxane blocked with trimethyl siloxy groups on both ends of the molecular chain, with a viscosity of 20 mPa.Math.s, (C) an amount of a chloroplatinic acid/1,3-divinyl-1,1,3,3-tetramethyl disiloxane complex (platinum metal inclusion proportion: 0.6 mass %) such that the amounts of platinum metal in the overall composition were 195 and 260 ppm; and (D1) 0.23 parts 1-ethenyl-1-cyclohexanol (ETCH) and 0.01 parts methyl (tris (1,1-dimethyl-2-propynyloxy)) silane. For the compositions of each of the amounts of platinum, cured layers were formed on thermally sensitive papers through the curing temperatures and curing times shown in Table 1 in a hot air circulating oven, where the results of the evaluations of curability, and the like, are shown in Table 1. Note that in Composition 1 the substance ratio of the silicon atom-bonded hydrogen atoms in the (B1-1) and (B1-2) components to the vinyl part in the (A) component (=SiH/Vi ratio) was 1.95.

[Embodiment 2] Composition 2

(19) A curable organopolysiloxane composition was produced in the same manner as in Embodiment 1, except for the further addition, to Composition 1, described above, of (E) 0.01 parts of diethoxy acetophenone. For the compositions with each of the amounts of platinum, cured layers were formed on thermally sensitive papers with the curing temperatures and curing times shown in Table 1, and the curabilities thereof are shown in Table 1. However, Composition 2 is ultraviolet radiation curable, and thus after the cured layer was formed on the thermally sensitive paper with the curing temperatures and curing times shown in Table 1 in a hot air circulating oven, it was further exposed to ultraviolet radiation (Eye Grande, by Eye Graphics Co., Ltd., total radiation dose: 110 mJ/cm.sup.2), to form a cured layer on the thermally sensitive paper, where the results of evaluations of curability, etc., are given in Table 1. The SiH/Vi ratio for Composition 2 was 1.95, the same as for Composition 1.

[Reference Example 1] Reference Composition 1

(20) A curable organopolysiloxane composition was produced in the same manner as in Embodiment 1, except for mixing in (AX) 93.76 parts of a polydimethyl siloxane having vinyl groups on both ends of the molecular chain and on a side chain (viscosity: 200 mPa.Math.s, vinyl (CH.sub.2?CH) group inclusion proportion: 1.20 mass %), instead of the component (A), and, for Component (C), mixing in the platinum metal in amounts of 195, 260, and 325 ppm in the composition as a whole. For the compositions of each of the amounts of platinum, cured layers were formed on thermally sensitive papers through the curing temperatures and curing times shown in Table 1 in a hot air circulating oven, where the results of the evaluations of curability, and the like, are shown in Table 1. Note that in Reference Composition 1 the substance ratio of the silicon atom-bonded hydrogen atoms in the (B1-1) and (B1-2) components to the vinyl part in the (AX) component (=SiH/Vi ratio) was 1.96.

[Reference Example 2] Reference Composition 2

(21) A curable organopolysiloxane composition was produced in the same manner as in Embodiment 1, except for using (AX) 90.76 parts of a polydimethyl siloxane having vinyl groups on both ends of the molecular chain and on a side chain (viscosity: 200 mPa.Math.s, vinyl (CH.sub.2?CH) group inclusion proportion: 1.20 mass %), instead of the component (A), mixing in (B1-1) 4.50 parts dimethyl methylhydrogen polysiloxane blocked with trimethyl siloxy groups on both ends of the molecular chain, with a viscosity of 25 mPa.Math.s, and (B1-2) 4.50 parts dimethyl methylhydrogen polysiloxane blocked with trimethyl siloxy groups on both ends of the molecular chain, with a viscosity of 20 mPa.Math.s, and, for Component (C), mixing in the platinum metal in amounts of 195, 260, and 325 ppm in the composition as a whole. For the compositions of each of the amounts of platinum, cured layers were formed on thermally sensitive papers through the curing temperatures and curing times shown in Table 1 in a hot air circulating oven, where the results of the evaluations of curability, and the like, are shown in Table 1. Note that in Reference Composition 2 the substance ratio of the silicon atom-bonded hydrogen atoms in the (B1-1) and (B1-2) components to the vinyl part in the (AX) component (=SiH/Vi ratio) was 3.00.

(22) TABLE-US-00001 TABLE 1 Embodiment 2 (Using hexenyl Embodiment groups) Reference Reference For all: 1 (Using *Together Example 1 Example 2 Discoloration hexenyl with UV (Using vinyl (Using vinyl of Thermally groups) curing groups) groups) Sensitive Embodiments SiH/Vi = 1.95 SiH/Vi = 1.95 SiH/Vi = 1.96 SiH/Vi = 3.00 Paper Amount of Platinum 195 260 195 260 195 260 325 195 260 325 (Pt) Catalyst ppm Curing 80? C. ? 30 s X ? ? ? X X X X X X ? Conditions 90? C. ? 30 s ? ? ? ? X X X X X ? ? 100? C. ? 30 s ? ? ? ? X X X X X ? ? 110? C. ? 30 s ? ? ? ? X X ? X ? ? ? Peeling Initial: 360 320 280 270 950 Force One-day (mN/5 cm) * curing 100? C. ? Time- 290 290 260 270 700 30 s elapsed: One-week curing Pot life at 40? C. (Does ? ? ? ? ? ? ? ? ? X not gellify for at least 4 hours)

Summary of Embodiments 1 Through 2 and Reference Example 1

(23) Given whether or not there was discoloration of the thermally sensitive paper, when a releasing layer was formed using the curable organopolysiloxane composition on the thermally sensitive paper, it was necessary to use a temperature of less than 1100 for a curing time of 30 seconds, and curing at a temperature of more than that could not solve the problem in the present invention effectively. Here, in Embodiment 1 and Embodiment 2, for both of the amount of the platinum (Pt) catalyst, 195 ppm and 260 ppm, the releasing layer could not be formed on the thermally sensitive paper at a low temperature of no more than 100? C., and the peeling force was in a range between 260 and 360 mN/5 cm, and exhibited a relatively light peeling force. Additionally, the composition had a pot life that was adequate for practical purposes, without gellification for at least 4 hours at 40? C.

(24) On the other hand, in Reference Example 1, the releasing layer could not be formed on the thermally sensitive paper at a low temperature of no greater than 100? C. Moreover, in Reference Example 2, while the releasing layer could not be formed on the thermally sensitive paper at a low temperature of no greater than 100? C. when the amount of platinum (Pt) catalyst was designed to 325 ppm, the initial peeling force was an extremely heavy peeling force of 950 mN/5 cm, and there was an extremely large change in peeling force after time elapsed. Furthermore, because the composition gellifies within one hour at 40? C., the ease of handling in an industrial production process is remarkably bad. For the reasons described above, even when the amount of the platinum (Pt) catalyst was designed to 325 ppm in the composition in Reference Example 2, it was not suitable for a releasing agent composition for use with a thermally sensitive paper.

[Embodiment 3-1] Composition 3-1

(25) An additional (B2) 0.50 parts of dimethyl methyl hydrogen polysiloxane blocked with trimethylsiloxy groups on both ends of the molecular chain, with a viscosity of 200 mPa.Math.s was added to Composition 1, above, to produce a Composition 3-1. Note that in Composition 1 the substance ratio of the silicon atom-bonded hydrogen atoms in the (B1) through (B3) components to the vinyl part in the (A) component (=SiH/Vi ratio) was 2.16.

[Embodiment 3-2] Composition 3-2

(26) An additional (B2) 1.0 parts of dimethyl methyl hydrogen polysiloxane blocked with trimethylsiloxy groups on both ends of the molecular chain, with a viscosity of 200 mPa.Math.s was added to Composition 1, above, to produce a Composition 3-1. Note that in Composition 1 the substance ratio of the silicon atom-bonded hydrogen atoms in the (B1) through (B3) components to the vinyl part in the (A) component (=SiH/Vi ratio) was 2.36.

(27) Composition 1, Composition 3-1, and Composition 3-2, above, were coated in an amount to produce 1.0 g/m.sup.2 siloxane equivalent onto a commercially available thermally sensitive paper (Thermal Paper 135LA-1, manufactured by Ricoh Co., Ltd.) using a printing suitability tester (Tester Sangyo Co., Ltd., RI-2) followed by curing for 30 seconds at 100? C. to cure the various compositions onto thermally sensitive papers, to produce thermally sensitive papers equipped with releasing layers. Note that no color development/discoloration was seen in the thermally sensitive papers. For the thermally sensitive papers provided with these releasing layers, adhesion evaluations were carried out for the releasing layer at the various conditions, with the results shown in Table 2.

(28) TABLE-US-00002 TABLE 2 <Adhesion Evaluation Results> Embodi- Embodiment Embodiment *100? C. ? 30 s ment 1 3-1 3-2 Initial ? ? ? 23? C., humidity 80% After 3 days 40? C., humidity 90% ? ? ? After 1 day Same, after 3 days ? ? ? Same, after 7 days ? ? ? Same, after 10 days ? ? ?

Summary for Embodiment 1 and Embodiments 3-1 and 3-2

(29) The thermally sensitive paper equipped with the releasing layer produced through Embodiment 1 was provided with adequate adhesion under conditions of 23? C. and humidity of 80%, but under harsher conditions of 40? C. and humidity of 90%, as the number of days elapsed, adhesion failures occurred. However, in Embodiments 3-1 and 3-2, which further included the (B2) component, there was good adhesion even after 10 days elapsed at 40? C. and humidity of 90%, confirming that the use of the (B2) component enabled achievement of superior adhesion.