JP4335079B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material in which a heat-sensitive color developing layer containing a leuco dye and a developer as main components is provided on a support.

  Usually, a recording layer comprising a colorless to light-colored electron-donating basic dye and an organic or inorganic electron-accepting substance as main components and a binder, filler, sensitizer, lubricant, etc. disposed thereon as a support. The recording material provided above is well known as a heat-sensitive recording material that utilizes a color reaction caused by fusion contact between functional units by heat. (Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. 45-14039, etc.).

  Since such a heat-sensitive recording material has a recording function preliminarily applied to a support (paper, synthetic paper, synthetic resin film, etc.), an image can be obtained simply by applying heat, such as a thermal head, a thermal pen, or a laser beam. No complicated development process is required, and the structure of the output device is relatively simple, compact, and easy to maintain. Facsimile, industrial measuring terminal, medical terminal, handy terminal, POS system, Widely used as an output sheet for various printers, including ticketing systems.

  However, since the above-mentioned heat-sensitive recording material is used in various environments with the expansion of the application range in recent years, it has the following problems in daily handling. In other words, the storage stability of the recording layer, such as falling off of the recording layer when water touches the heat-sensitive recording material, disappearance of the recorded image when touching a plastic film or sheet containing a plasticizer, and coloring when touching an organic solvent, etc. It was not satisfactory enough.

  In order to eliminate such drawbacks, thermal recording materials provided with various protective layers and backcoat layers have been proposed.

  In addition, these thermal recording materials improve the slidability with the thermal head, and in order to make the printing smooth, wax such as metal soap is added to the surface layer, or the thermal head and the surface of the thermal recording material are stuck ( In most cases, fillers (pigments) such as aluminum hydroxide, silica, and calcium carbonate are added to remove the so-called head debris that sticks to the thermal head during sticking and printing. . However, the wax as a slipping agent has a drawback that the plasticizer resistance of the protective layer is lowered instead of increasing the heat resistance (running stability) of the surface of the heat-sensitive recording material. In addition, if a good wax is used for the plasticizer resistance, the running stability will be insufficient because the running stability will be insufficient and the printing noise will increase during printing and sticking will cause inconvenience. And plasticizer resistance could not be achieved at the same time.

As a wax, zinc stearate is relatively compatible in running stability and plasticizer resistance, but the plasticizer resistance is still insufficient. On the other hand, as a wax, Montan wax has a relatively compatible quality and has sufficient plasticizer resistance, but its running stability is slightly insufficient, and there is no problem with print quality. There is a problem in that the printing sound during printing is loud.
Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039

  The object of the present invention is to improve running stability, plasticizer resistance and the like by improving the slipperiness when a specific polyolefin wax is used as a lubricant for the protective layer, which solves the above-mentioned conventional problems. It is to provide a heat-sensitive recording material.

That is, the present invention is a thermosensitive recording material in which a thermosensitive coloring layer that develops color by heat is provided on a support and a protective layer is provided on the upper surface thereof, and in this protective layer, gel permeation chromatography (GPC) The number average molecular weight (Mn) measured in (1) is in the range of 400 to 5,000, the melting point measured with a differential scanning calorimeter (DSC) is in the range of 65 to 130 ° C., and the density measured by the density gradient tube method ( D) is in the range of 850 to 980 kg / m ³ , the crystallization temperature (Tc (° C.), measured at a temperature drop rate of 2 ° C./min) measured with a differential scanning calorimeter (DSC) and the density (D (kg / m ³ )) is represented by the following formula (I)
0.501 × D-366 ≧ Tc (I)
Is a heat-sensitive recording material comprising a polyolefin wax satisfying the above.

  The heat-sensitive recording material of the present invention is excellent in running stability by using a specific polyolefin wax as a lubricant in the protective layer. Therefore, it has improved the problems of running stability, glossiness, water resistance, etc., which have been improved in recent years by improving problems such as insufficient running stability, increased printing noise during printing, sticking, and inconvenience in printing. In addition, it can sufficiently meet demands for plasticizer resistance and the like.

(Polyolefin wax)
The polyolefin wax used in the present invention is an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

  Here, the α-olefin is preferably an α-olefin having 3 to 10 carbon atoms, more preferably propylene having 3 carbon atoms, 1-butene having 4 carbon atoms, 1-pentene having 5 carbon atoms. , 1-hexene having 6 carbon atoms, 4-methyl-1-pentene, 1-octene having 8 carbon atoms, etc., preferably propylene, 1-butene, 1-hexene, 4-methyl-1-pentene. It is.

  The polyolefin wax used in the present invention has a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of 400 to 5,000, preferably 1,000 to 4,000, more preferably 1,500 to 5,000. It is in the range of 4,000.

   The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn) measured by gel permeation chromatography (GPC) is usually 1.1 to 5.0 for the polyolefin wax used in the present invention. Preferably, it is in the range of 1.2 to 4.5, more preferably 1.2 to 4.0. In addition, a weight average molecular weight (Mw) and a number average molecular weight (Mn) are the values of polystyrene conversion by gel permeation chromatography (GPC), and the measurement by GPC is the conditions of temperature: 140 ° C., solvent: orthodichlorobenzene. Done under.

  When Mw / Mn is within the above range, the low-tail component and the high-tail component are reduced, so that a uniform polyolefin wax emulsion tends to be formed.

The polyolefin wax used in the present invention desirably has an intrinsic viscosity [η] measured in decalin at 135 ° C. of 0.04 to 0.47 dl · g ⁻¹ , preferably 0.05 to 0.47 dl · g. ^-1, more preferably 0.07~0.20dl · ^{g -1,} even more preferably in the range of 0.08~0.18dl · ^{g -1.}

  The polyolefin wax used in the present invention has a melting point measured by a differential scanning calorimeter (DSC) in the range of 65 to 130 ° C, preferably 70 to 120 ° C, more preferably 80 to 110 ° C.

The polyolefin wax used in the present invention has a density (D) measured by a density gradient tube method of 850 to 980 kg / m ³ , preferably 870 to 970 kg / m ³ , more preferably 880 to 960 kg / m ^3. .

The polyolefin wax used in the present invention has a crystallization temperature measured with a differential scanning calorimeter (DSC) (Tc (° C.), measured at a temperature drop rate of 2 ° C./min) and a density measured with a density gradient tube method (D ( kg / m ³ )) is represented by the following formula (I)
0.501 × D-366 ≧ Tc (I)
Preferably, the following formula (Ia)
0.501 × D-366.5 ≧ Tc (Ia)
More preferably, the following formula (Ib)
0.501 × D-367 ≧ Tc (Ib)
Meet.

  If the relationship between the crystallization temperature (Tc) and the density (D) in the polyolefin wax satisfies the above formula, the comonomer composition of the polyolefin wax becomes more uniform, resulting in a decrease in the sticky component of the polyolefin wax and the inclusion of the polyolefin wax. Of thermal recording material. Running stability and plasticizer resistance tend to be improved.

  The polyolefin wax used in the present invention desirably has a penetration of 30 dmm or less, preferably 25 dmm or less, more preferably 20 dmm or less, and even more preferably 15 dmm or less. The penetration can be measured according to JIS K2207.

  When the penetration of the polyolefin wax satisfies the above range, the running stability and plasticizer resistance of the heat-sensitive recording material containing the polyolefin wax tend to be improved.

  The polyolefin wax used in the present invention has an acetone extraction amount of preferably 0 to 20% by weight, more preferably 0 to 15% by weight. The amount of acetone extracted is measured as follows.

  Using a filter (made by ADVANCE, No. 84) with a Soxhlet extractor (made of glass), 10 g of wax was set on the filter, and 200 ml of acetone was charged into a lower round bottom flask (300 ml) at 70 ° C. Extract in a hot water bath for 5 hours. Polyolefin wax is solid at normal temperature and becomes a low-viscosity liquid at 65 to 130 ° C. or higher.

  The polyolefin wax as described above is produced using, for example, the following metallocene catalyst comprising a metallocene compound of a transition metal selected from Group 4 of the periodic table and an organoaluminum oxy compound and / or an ionized ionic compound. be able to

(Metallocene compound)
The metallocene compound that forms the metallocene catalyst is a metallocene compound of a transition metal selected from Group 4 of the periodic table, and specific examples include compounds represented by the following general formula (1).
M ¹ Lx (1)

Here, M ¹ is a transition metal selected from Group 4 of the periodic table, x is a valence of the transition metal M ¹ , and L is a ligand. Examples of the transition metal represented by M ¹ include zirconium, titanium, hafnium and the like. L is a ligand coordinated to the transition metal M ^1, and at least one of the ligands L is a ligand having a cyclopentadienyl skeleton, and the ligand having this cyclopentadienyl skeleton. The ligand may have a substituent. Examples of the ligand L having a cyclopentadienyl skeleton include a cyclopentadienyl group, a methylcyclopentadienyl group, an ethylcyclopentadienyl group, an n- or i-propylcyclopentadienyl group, n-, alkyl such as i-, sec- or t-butylcyclopentadienyl group, dimethylcyclopentadienyl group, methylpropylcyclopentadienyl group, methylbutylcyclopentadienyl group, methylbenzylcyclopentadienyl group, An alkyl-substituted cyclopentadienyl group; and an indenyl group, 4,5,6,7-tetrahydroindenyl group, a fluorenyl group, and the like. The hydrogen of the ligand having a cyclopentadienyl skeleton may be substituted with a halogen atom or a trialkylsilyl group.

  When the metallocene compound has two or more ligands having a cyclopentadienyl skeleton as the ligand L, the ligands having two cyclopentadienyl skeletons are ethylene, propylene. Or a substituted alkylene group such as isopropylidene or diphenylmethylene; a substituted silylene group such as a silylene group or a dimethylsilylene group, a diphenylsilylene group, or a methylphenylsilylene group.

Examples of ligands other than ligands having a cyclopentadienyl skeleton (ligands having no cyclopentadienyl skeleton) L include hydrocarbon groups having 1 to 12 carbon atoms, alkoxy groups, aryloxy groups, sulfones. Acid-containing group (—SO ₃ R ¹ ), halogen atom or hydrogen atom (where R ¹ is an alkyl group, an alkyl group substituted with a halogen atom, an aryl group, an aryl group substituted with a halogen atom, or an alkyl group) A substituted aryl group).

(Example 1 of metallocene compound)
When the metallocene compound represented by the general formula (1) has a transition metal valence of 4, for example, it is more specifically represented by the following general formula (2).
R ² _k R ³ _l R ⁴ _m R ⁵ _n M ¹ (2)
Here, M ¹ is a transition metal selected from Group 4 of the periodic table, R ² is a group (ligand) having a cyclopentadienyl skeleton, and R ³ , R ⁴ and R ⁵ are each independently cyclopentadienyl. A group (ligand) having or not having a skeleton. k is an integer of 1 or more, and k + l + m + n = 4.

Examples of metallocene compounds in which M ¹ is zirconium and contains at least two ligands having a cyclopentadienyl skeleton are given below. Bis (cyclopentadienyl) zirconium monochloride monohydride, bis (cyclopentadienyl) zirconium dichloride, bis (1-methyl-3-butylcyclopentadienyl) zirconium bis (trifluoromethanesulfonate), bis (1, 3-dimethylcyclopentadienyl) zirconium dichloride and the like.

  Among the above compounds, compounds in which the 1,3-position substituted cyclopentadienyl group is replaced with a 1,2-position substituted cyclopentadienyl group can also be used.

As another example of the metallocene compound, in the general formula (2), at least two of R ² , R ³ , R ⁴ and R ⁵ , for example, R ² and R ³ are groups having a cyclopentadienyl skeleton ( A bridge type metallocene compound in which at least two groups are bonded via an alkylene group, a substituted alkylene group, a silylene group, a substituted silylene group, or the like. At this time, R ⁴ and R ⁵ are each independently the same as the ligand L other than the ligand having the cyclopentadienyl skeleton described above.

  Examples of such bridge-type metallocene compounds include ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, diphenylsilylenebis (indenyl) zirconium dichloride, methyl Examples include phenylsilylene bis (indenyl) zirconium dichloride.

(Example 2 of metallocene compound)
Moreover, as an example of a metallocene compound, the metallocene compound of Unexamined-Japanese-Patent No. 4-268307 represented by following General formula (3) is mentioned.

Here, M ¹ is a Group 4 transition metal of the periodic table, and specifically includes titanium, zirconium, and hafnium.

R ¹¹ and R ¹² may be the same or different from each other, and are a hydrogen atom; an alkyl group having 1 to 10 carbon atoms; an alkoxy group having 1 to 10 carbon atoms; an aryl group having 6 to 10 carbon atoms; Aryloxy group having 6 to 10 carbon atoms; alkenyl group having 2 to 10 carbon atoms; arylalkyl group having 7 to 40 carbon atoms; alkylaryl group having 7 to 40 carbon atoms; arylalkenyl group having 8 to 40 carbon atoms Or a halogen atom, and R ¹¹ and R ¹² are preferably chlorine atoms.

R ¹³ and R ¹⁴ may be the same or different from each other, and are a hydrogen atom; a halogen atom; an optionally halogenated alkyl group having 1 to 10 carbon atoms; an aryl group having 6 to 10 carbon atoms; (R ²⁰ ) ₂ , —SR ²⁰ , —OSi (R ²⁰ ) ₃ , —Si (R ²⁰ ) ₃ or —P (R ²⁰ ) ₂ groups. R ²⁰ is a halogen atom, preferably a chlorine atom; an alkyl group having 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms; or an aryl group having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms. R ¹³ and R ¹⁴ are particularly preferably hydrogen atoms.

R ¹⁵ and R ¹⁶ are the same as R ¹³ and R ¹⁴ except that they do not contain a hydrogen atom, and may be the same or different from each other, preferably the same. R ¹⁵ and R ¹⁶ are preferably an optionally halogenated alkyl group having 1 to 4 carbon atoms, specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, trifluoromethyl and the like. Particularly preferred is methyl.
In the general formula (3), R ¹⁷ is selected from the following group.

^{= BR 21, = AlR 21,} -Ge -, - Sn -, - O -, - S -, = SO, = SO 2, = NR 21, = CO, = PR 21, = P (O) R 21 , etc. . M ² is silicon, germanium or tin, preferably silicon or germanium. Here, R ²¹ , R ²² and R ²³ may be the same or different from each other, and are hydrogen atom; halogen atom; alkyl group having 1 to 10 carbon atoms; fluoroalkyl group having 1 to 10 carbon atoms; carbon atom An aryl group having 6 to 10 carbon atoms; a fluoroaryl group having 6 to 10 carbon atoms; an alkoxy group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; an arylalkyl group having 7 to 40 carbon atoms; An arylalkenyl group having 8 to 40 carbon atoms; or an alkylaryl group having 7 to 40 carbon atoms. “R ²¹ and R ²² ” or “R ²¹ and R ²³ ” may form a ring together with the atoms to which they are bonded. R ¹⁷ may be = CR ²¹ R ²² , = SiR ²¹ R ²² , = GeR ²¹ R ²² , -O-, -S-, = SO, = PR ²¹ or = P (O) R ^21. preferable. R ¹⁸ and R ¹⁹ may be the same as or different from each other, and examples thereof include the same as R ²¹ . m and n may be the same or different and are each 0, 1 or 2, preferably 0 or 1, and m + n is 0, 1 or 2, preferably 0 or 1.

Examples of the metallocene compound represented by the general formula (3) include the following compounds. rac-ethylene (2-methyl-1-indenyl) ₂ -zirconium dichloride, rac-dimethylsilylene (2-methyl-1-indenyl) ₂ -zirconium dichloride, and the like. These metallocene compounds can be produced, for example, by the method described in JP-A-4-268307.

(Example 3 of metallocene compound)
Moreover, as a metallocene compound, the metallocene compound represented by following General formula (4) can also be used.

In Formula (4), M ³ represents a transition metal atom of Group 4 of the periodic table, and specifically, titanium, zirconium, hafnium, and the like. R ²⁴ and R ²⁵ may be the same or different and are each a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, oxygen A containing group, a sulfur-containing group, a nitrogen-containing group or a phosphorus-containing group; R ²⁴ is preferably a hydrocarbon group, and particularly preferably an alkyl group having 1 to 3 carbon atoms such as methyl, ethyl or propyl. R ²⁵ is preferably a hydrogen atom or a hydrocarbon group, particularly preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms such as methyl, ethyl or propyl. R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may be the same or different from each other, and are a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon having 1 to 20 carbon atoms. Indicates a group. Among these, a hydrogen atom, a hydrocarbon group, or a halogenated hydrocarbon group is preferable. At least one of R ²⁶ and R ²⁷ , R ²⁷ and R ²⁸ , and R ²⁸ and R ²⁹ may form a monocyclic aromatic ring together with the carbon atoms to which they are bonded. Good. When there are two or more hydrocarbon groups or halogenated hydrocarbon groups other than the group forming the aromatic ring, they may be bonded to each other to form a ring. When R ²⁹ is a substituent other than an aromatic group, it is preferably a hydrogen atom. X ¹ and X ² may be the same or different from each other, and are a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an oxygen atom-containing group or Y representing a sulfur atom-containing group is a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a divalent silicon-containing group, or divalent germanium. containing group, a divalent tin-containing group, -O -, - CO -, - S -, - SO -, - SO 2 -, - NR 30 -, - P (R 30) -, - P (O) ( R ³⁰ ) —, —BR ³⁰ — or —AlR ³⁰ — (wherein R ³⁰ is a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms). Indicates.

In the formula (4), at least one pair of R ²⁶ and R ²⁷ , R ²⁷ and R ²⁸ , R ²⁸ and R ²⁹ is bonded to each other, and is coordinated to M ³ Examples of the ligand include those represented by the following formula.

（式中、Ｙは前式に示したものと同じである。）

(In the formula, Y is the same as that shown in the previous formula.)

(Example 4 of metallocene compound)
As the metallocene compound, a metallocene compound represented by the following general formula (5) can also be used.

In the formula (5), M ³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ are the same as those in the general formula (4). Of R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ , two groups including R ²⁶ are preferably alkyl groups, and R ²⁶ and R ²⁸ , or R ²⁸ and R ²⁹ are alkyl groups. preferable. This alkyl group is preferably a secondary or tertiary alkyl group. The alkyl group may be substituted with a halogen atom or a silicon-containing group. Examples of the halogen atom and silicon-containing group include the substituents exemplified for R ²⁴ and R ²⁵ . Of R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ , the group other than the alkyl group is preferably a hydrogen atom. R ²⁶ , R ²⁷ , R ^28, and R ²⁹ may form a monocyclic ring or a polycyclic ring other than an aromatic ring by combining two groups selected from these groups. Examples of the halogen atom are the same as those described above for R ²⁴ and R ²⁵ . Examples of X ¹ , X ² and Y are the same as those described above.

  Specific examples of the metallocene compound represented by the general formula (5) are shown below. rac-dimethylsilylene-bis (4,7-dimethyl-1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2,4,7-trimethyl-1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2 , 4,6-trimethyl-1-indenyl) zirconium dichloride and the like.

  In these compounds, transition metal compounds in which zirconium metal is replaced with titanium metal or hafnium metal can also be used. The transition metal compound is usually used as a racemate, but can also be used in the R-type or S-type.

(Example of metallocene compound-5)
As the metallocene compound, a metallocene compound represented by the following general formula (6) can also be used.

In the formula (6), M ³ , R ²⁴ , X ¹ , X ² and Y are the same as those in the general formula (4). R ²⁴ is preferably a hydrocarbon group, particularly preferably an alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, propyl or butyl. R ²⁵ represents an aryl group having 6 to 16 carbon atoms. R ²⁵ is preferably phenyl or naphthyl. The aryl group may be substituted with a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms. X ¹ and X ² are preferably a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

  Specific examples of the metallocene compound represented by the general formula (6) are shown below. rac-dimethylsilylene-bis (4-phenyl-1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2-methyl-4-phenyl-1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2-methyl) -4- (α-naphthyl) -1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2-methyl-4- (β-naphthyl) -1-indenyl) zirconium dichloride, rac-dimethylsilylene-bis (2 -Methyl-4- (1-anthryl) -1-indenyl) zirconium dichloride and the like. In these compounds, transition metal compounds in which zirconium metal is replaced with titanium metal or hafnium metal can also be used.

(Example of metallocene compound-6)
As the metallocene compound, a metallocene compound represented by the following general formula (7) can also be used.
LaM ⁴ X ³ ₂ (7)

Here, M ⁴ is a periodic table group 4 or lanthanide series metal. La is a derivative of a delocalized π bond group, and is a group imparting a constraining geometry to the metal M ⁴ active site. X ³ may be the same or different from each other, and is a hydrogen atom, a halogen atom, a hydrocarbon group having 20 or less carbon atoms, a silyl group containing 20 or less silicon, or a germanyl group containing 20 or less germanium.
Among these compounds, a compound represented by the following formula (8) is preferable.

In the formula (8), M ⁴ is titanium, zirconium or hafnium. X ³ is the same as that described in the general formula (7). Cp is a substituted cyclopentadienyl group having a π bond to M ⁴ and having a substituent Z. Z is oxygen, sulfur, boron or an element belonging to Group 4 of the periodic table (for example, silicon, germanium or tin). Y is a ligand containing nitrogen, phosphorus, oxygen or sulfur, and Z and Y may form a condensed ring. Specific examples of the metallocene compound represented by the formula (8) are shown below. (Dimethyl (t-butylamide) (tetramethyl-η ⁵ -cyclopentadienyl) silane) titanium dichloride, ((t-butylamide) (tetramethyl-η ⁵ -cyclopentadienyl) -1,2-ethanediyl) titanium Dichloride etc. In the metallocene compound, a compound in which titanium is replaced with zirconium or hafnium can be exemplified.

(Example 7 of metallocene compound)
Moreover, as a metallocene compound, the metallocene compound represented by following General formula (9) can also be used.

In formula (9), M ³ is a transition metal atom of Group 4 of the periodic table, specifically titanium, zirconium or hafnium, preferably zirconium. R ³¹ may be the same as or different from each other, and at least one of them is an aryl group having 11 to 20 carbon atoms, an arylalkyl group having 12 to 40 carbon atoms, an arylalkenyl group having 13 to 40 carbon atoms, carbon An alkylaryl group having 12 to 40 atoms or a silicon-containing group, or at least two adjacent groups among the groups represented by R ³¹ , together with the carbon atoms to which they are bonded, one or more aromatic rings Or an aliphatic ring is formed. In this case, the ring formed by R ^31, it is 4 to 20 carbon atoms in all including carbon atoms to which R ³¹ is bonded. Aryl group, arylalkyl group, arylalkenyl group, an alkylaryl group and an aromatic ring, R ³¹ other than R ³¹ that forms an aliphatic ring is a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms Or a silicon-containing group. R ³² may be the same as or different from each other, and may be a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a carbon atom. An arylalkyl group having 7 to 40 carbon atoms, an arylalkenyl group having 8 to 40 carbon atoms, an alkylaryl group having 7 to 40 carbon atoms, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group or a phosphorus-containing group It is. Further, at least two adjacent groups among the groups represented by R ³² may form one or more aromatic rings or aliphatic rings together with the carbon atoms to which they are bonded. In this case, the ring formed by R ³² has 4 to 20 carbon atoms in all including carbon atoms to which R ³² is bonded, an aromatic ring, other than R ³² that forms an aliphatic ring R ³² is a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a silicon-containing group. The group in which the two groups represented by R ^{32 form} one or more aromatic rings or aliphatic rings includes an embodiment in which the fluorenyl group has a structure represented by the following formula.

R ³² is preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms such as methyl, ethyl or propyl. A suitable example of such a fluorenyl group having R ³² as a substituent is a 2,7-dialkyl-fluorenyl group. In this case, the 2,7-dialkyl alkyl group includes 1 to 1 carbon atoms. 5 alkyl groups. R ³¹ and R ³² may be the same as or different from each other. R ³³ and R ³⁴ may be the same as or different from each other, and are the same hydrogen atom, halogen atom, alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, and 2 to 2 carbon atoms. 10 alkenyl groups, arylalkyl groups having 7 to 40 carbon atoms, arylalkenyl groups having 8 to 40 carbon atoms, alkylaryl groups having 7 to 40 carbon atoms, silicon-containing groups, oxygen-containing groups, sulfur-containing groups, A nitrogen-containing group or a phosphorus-containing group. Of these, at least one of R ³³ and R ³⁴ is preferably an alkyl group having 1 to 3 carbon atoms. X ¹ and X ² may be the same or different and are each a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an oxygen-containing group, sulfur A conjugated diene residue formed from a containing group or a nitrogen-containing group, or X ¹ and X ² . As the conjugated diene residue formed from X ¹ and X ² , residues of 1,3-butadiene, 2,4-hexadiene, 1-phenyl-1,3-pentadiene and 1,4-diphenylbutadiene are preferable. These residues may be further substituted with a hydrocarbon group having 1 to 10 carbon atoms. X ¹ and X ² are preferably a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a sulfur-containing group. Y is a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a divalent silicon-containing group, a divalent germanium-containing group, a divalent tin-containing group, -O -, - CO -, - S -, - SO -, - SO 2 -, - NR 35 -, - P (R 35) -, - P (O) (R 35) -, - BR ³⁵ — or —AlR ³⁵ — (wherein R ³⁵ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms). Among these divalent groups, those in which the shortest linking portion of -Y- is composed of one or two atoms are preferable. R ³⁵ is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms. Y is preferably a divalent hydrocarbon group having 1 to 5 carbon atoms, a divalent silicon-containing group or a divalent germanium-containing group, more preferably a divalent silicon-containing group. Particularly preferred is silylene, alkylarylsilylene or arylsilylene.

(Example of metallocene compound-8)
As the metallocene compound, a metallocene compound represented by the following general formula (10) can also be used.

In formula (10), M ³ is a transition metal atom of Group 4 of the periodic table, specifically titanium, zirconium or hafnium, preferably zirconium. R ³⁶ may be the same as or different from each other, and includes a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and silicon-containing Group, oxygen-containing group, sulfur-containing group, nitrogen-containing group or phosphorus-containing group. The alkyl group and alkenyl group may be substituted with a halogen atom. Of these, R ³⁶ is preferably an alkyl group, an aryl group or a hydrogen atom, particularly a hydrocarbon group having 1 to 3 carbon atoms such as methyl, ethyl, n-propyl and i-propyl, phenyl, α-naphthyl. And an aryl group such as β-naphthyl or a hydrogen atom. R ³⁷ may be the same or different from each other, and may be a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a carbon atom. An arylalkyl group having 7 to 40 carbon atoms, an arylalkenyl group having 8 to 40 carbon atoms, an alkylaryl group having 7 to 40 carbon atoms, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group or a phosphorus-containing group It is. Note that the alkyl group, aryl group, alkenyl group, arylalkyl group, arylalkenyl group, and alkylaryl group may be substituted with halogen. Of these, R ³⁷ is preferably a hydrogen atom or an alkyl group, and particularly a hydrogen atom or a carbon atom having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, i-propyl, n-butyl, or tert-butyl. A hydrogen group is preferred. R ³⁶ and R ³⁷ may be the same as or different from each other. One of R ³⁸ and R ³⁹ is an alkyl group having 1 to 5 carbon atoms, and the other is a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. A silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group or a phosphorus-containing group. Among these, it is preferable that any one of R ³⁸ and R ³⁹ is an alkyl group having 1 to 3 carbon atoms such as methyl, ethyl, and propyl, and the other is a hydrogen atom. X ¹ and X ² may be the same or different and are each a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an oxygen-containing group, sulfur A conjugated diene residue formed from a containing group or a nitrogen-containing group, or X ¹ and X ² . Among these, a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms is preferable. Y is a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a divalent silicon-containing group, a divalent germanium-containing group, a divalent tin-containing group, -O -, - CO -, - S -, - SO -, - SO 2 -, - NR 40 -, - P (R 40) -, - P (O) (R 40) -, - BR ⁴⁰ — or —AlR ⁴⁰ — (wherein R ⁴⁰ is a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms). Among these, Y is preferably a divalent hydrocarbon group having 1 to 5 carbon atoms, a divalent silicon-containing group, or a divalent germanium-containing group, and more preferably a divalent silicon-containing group. An alkylsilylene, an alkylarylsilylene or an arylsilylene is particularly preferable.

  The metallocene compounds described above are used alone or in combination of two or more. The metallocene compound may be diluted with a hydrocarbon or a halogenated hydrocarbon.

(Organic aluminum oxy compound)
The organoaluminum oxy compound may be a known aluminoxane or a benzene-insoluble organoaluminum oxy compound. Such a known aluminoxane is specifically represented by the following formula.

Here, R is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group or a butyl group, preferably a methyl group or an ethyl group, particularly preferably a methyl group, and m is 2 or more, preferably 5 to 40. Is an integer.

  The aluminoxane is an alkyloxyaluminum unit represented by the formula (OAl (R ′)) and an alkyloxyaluminum unit represented by the formula (OAl (R ″)) (where R ′ and R ″ are R And R ′ and R ″ represent different groups.) And may be formed from mixed alkyloxyaluminum units. The organic aluminum oxy compound may contain a small amount of an organic compound component of a metal other than aluminum.

(Ionized ionic compounds)
Examples of ionized ionic compounds (sometimes referred to as ionic ionized compounds and ionic compounds) include Lewis acids, ionic compounds, borane compounds, and carborane compounds. As the Lewis acid, a compound represented by BR ₃ (R is a phenyl group which may have a substituent such as a fluorine, a methyl group or a trifluoromethyl group or fluorine) can be used. Specific examples of the Lewis acid include trifluoroboron, triphenylboron, tris (4-fluorophenyl) boron, tris (3,5-difluorophenyl) boron, tris (4-fluoromethylphenyl) boron, tris ( Pentafluorophenyl) boron, tris (p-tolyl) boron, tris (o-tolyl) boron, tris (3,5-dimethylphenyl) boron and the like.

  Examples of the ionic compound include trialkyl-substituted ammonium salts, N, N-dialkylanilinium salts, dialkylammonium salts, and triarylphosphonium salts. Examples of the trialkyl-substituted ammonium salt as the ionic compound include triethylammonium tetra (phenyl) boron, tripropylammonium tetra (phenyl) boron, and tri (n-butyl) ammonium tetra (phenyl) boron. Examples of the dialkylammonium salt as the ionic compound include di (1-propyl) ammonium tetra (pentafluorophenyl) boron and dicyclohexylammonium tetra (phenyl) boron.

  Examples of the ionic compound include triphenylcarbenium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, ferrocenium tetra (pentafluorophenyl) borate, and the like. .

  Examples of the borane compound include decaborane (9); bis [tri (n-butyl) ammonium] nonaborate, bis [tri (n-butyl) ammonium] decaborate, bis [tri (n-butyl) ammonium] bis (dodecahydridododeca Examples thereof include salts of metal borane anions such as borate) nickelate (III).

  Examples of the carborane compound include 4-carbanonaborane (9), 1,3-dicarbanonaborane (8), bis [tri (n-butyl) ammonium] bis (undecahydride-7-carbaundecaborate) nickel acid. And salts of metal carborane anions such as salt (IV).

Such ionized ionic compounds may be used alone or in combination of two or more.
In forming the metallocene catalyst, the following organoaluminum compounds may be used together with the organoaluminum oxy compound and / or the ionized ionic compound.

(Organic aluminum compound)
As the organoaluminum compound used as necessary, a compound having at least one Al-carbon bond in the molecule can be used. As such a compound, for example, an organoaluminum represented by the following general formula (11) Compound,
_{^{(R 6) m Al (OR}} 7) n H p X 4 q ... (11)
(In the formula, R ⁶ and R ⁷ may be the same or different from each other, and are a hydrocarbon group usually containing 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms. X ⁴ is a halogen atom. Is a number satisfying 0 ≦ m <3, n is 0 ≦ n <3, p is 0 ≦ p <3, q is 0 ≦ q <3, and m + n + p + q = 3) and the following general formula ( And a complex alkylated product of Group 1 metal and aluminum represented by 12).
(M ⁵ ) Al (R ⁶ ) (12)
(In the formula, M ⁵ is Li, Na or K, and R ⁶ is the same as R ^{6 in the} general formula (11).)

(polymerization)
The polyolefin wax used in the present invention is obtained by homopolymerizing ethylene in a normal liquid phase or copolymerizing ethylene and an α-olefin in the presence of the metallocene catalyst. At this time, a hydrocarbon solvent is generally used, but an α-olefin may be used as a solvent. The monomers used here are as described above.

  The polymerization method includes suspension polymerization in which polyolefin wax is polymerized in the presence of particles in a solvent such as hexane, gas phase polymerization in which a solvent is not used, and polymerization temperature of 140 ° C. or higher. Solution polymerization that polymerizes in the coexistence or melted state is possible, and among these, solution polymerization is preferable in terms of both economy and quality.

  The polymerization reaction may be performed by either a batch method or a continuous method. When the polymerization is carried out by a batch method, the above catalyst components are used in the concentrations described below.

  The concentration of the metallocene compound in the polymerization system is usually 0.00005 to 0.1 mmol / liter (polymerization volume), preferably 0.0001 to 0.05 mmol / liter.

  The organoaluminum oxy compound is supplied in an amount of 1 to 10,000, preferably 10 to 5,000, in terms of the molar ratio of aluminum atom to transition metal in the metallocene compound in the polymerization system (Al / transition metal).

  The ionized ionic compound is represented by the molar ratio of the ionized ionic compound to the metallocene compound in the polymerization system (ionized ionic compound / metallocene compound), and is supplied in an amount of 0.5 to 20, preferably 1 to 10. .

  When an organoaluminum compound is used, it is generally used in an amount of about 0 to 5 mmol / liter (polymerization volume), preferably about 0 to 2 mmol / liter.

In the polymerization reaction, the temperature is usually 10 g of wax set on a filter, -20 to + 200 ° C., preferably 50 to 180 ° C., more preferably 70 to 180 ° C., and the pressure usually exceeds 0. It is performed under conditions of 8 MPa (80 kgf / cm ² , gauge pressure) or less, preferably more than 0 and 4.9 MPa (50 kgf / cm ² , gauge pressure) or less.

  In the polymerization, ethylene and the α-olefin used as necessary are supplied to the polymerization system in such an amount ratio that a polyolefin wax having the specific composition described above can be obtained. In the polymerization, a molecular weight regulator such as hydrogen can be added.

  When polymerized in this manner, the produced polymer is usually obtained as a polymerization solution containing the polymer, so that a polyolefin wax can be obtained by treatment by a conventional method.

  In the present invention, it is particularly preferable to use a catalyst containing the metallocene compound shown in (Example 6 of metallocene compound).

  In the present invention, the protective layer contains a polyolefin wax as a lubricant, but is preferably contained as a polyolefin wax emulsion. The polyolefin wax emulsion retains not only the effect as a lubricant but also the function of significantly increasing the running stability and heat resistance required for the protective layer. The addition amount of the polyolefin wax emulsion is usually in a range of 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass with respect to 100 parts by mass of the resin in terms of solid content. Part range. If it is 10 parts by mass or more, the film-forming property of the protective layer is impaired and coating film defects are liable to occur. In addition, when printing is performed on the protective layer, ink adhesion may be hindered. If the amount is less than 0.5 parts by mass, further improvement in function of running stability and heat stability cannot be expected.

  In the present invention, a pigment is also used, but the amount added is preferably 1 to 200 parts by mass with respect to 100 parts by mass of the resin. In the present invention, a silicone compound may be used. The addition amount is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the resin. If it is added more than this, the plasticizer resistance is lowered.

  In the present invention, the average particle size of the polyolefin wax emulsion is usually 2.0 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less. Examples of a method for dispersing in such a size include coexistence of a wax with an appropriate protective colloid and a surfactant, and a method of dispersing with a known wet disperser such as dynomill and sand mill. Once the wax is melted by heating, it is emulsified at a temperature equal to or higher than the melting point of the wax using a means used for usual fine particle emulsification such as high-speed stirring and ultrasonic dispersion in a solvent in which the wax is insoluble or hardly soluble. And a method in which the wax is dissolved in a suitable solvent and then emulsified in a solvent in which the wax is insoluble or hardly soluble. At this time, an appropriate surfactant or protective colloid may be used in combination. In order to improve the adhesion between the surface of the thermal paper and the head so as not to deteriorate the image quality, the average particle diameter of the polyolefin wax emulsion is preferably 2.0 μm or less.

  Various emulsifiers generally used as emulsifiers are used as emulsifiers for emulsifying and dispersing polyolefin wax. Specific examples thereof include, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyoxyethylene alkyl ether, polyoxyethylene alkyl. Nonionic surfactants such as phenyl ether, polyoxyethylene derivatives, oxyethylene / oxypropylene block copolymers, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkylnaphthalenes Sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates General dispersion / emulsifiers of anionic surfactants such as salt salts, naphthalenesulfonic acid formalin condensates, special polycarboxylic acid type polymer surfactants, polyoxyethylene alkyl phosphate esters, etc. And reactive emulsifiers having a saturated group. However, among these, those using polyvinyl alcohol are preferable from the viewpoint of background color development after coating and the stability of the coating solution, and those using acid-modified polyvinyl alcohol are particularly preferable.

  Further, two or more kinds of polyolefin waxes can be used in combination, or can be used in combination with other conventionally known waxes. Examples of waxes used in combination in this case include plant waxes such as candelilla wax, carnauba wax, rice wax, wax wax, jojoba oil, animal waxes such as beeswax, lanolin, and whale wax, montan wax, ceresin Mineral waxes and derivatives thereof, petroleum waxes such as paraffin, petrolatum, microcristan, petrolactam, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, hydrogenated castor oil, hydrogenated wax of hardened castor oil derivatives, stearin Acids, oleic acid, erucic acid, lauric acid, sebacic acid, behenic acid, palmitic acid, etc., amides such as adipic acid, isophthalic acid, bisamides, esters, ketones, metal salts and their derivatives, alkyl-modified or amide-modified Silicor Resins. Of course, these lubricants may be used in combination.

  A silicone compound can be added to the protective layer of the present invention. The addition of the silicone compound can be expected to improve lubricity. Various silicone resins and silicone rubbers are used as the silicone compound in this case, and room temperature curing type silicone rubber is particularly preferable from the viewpoint of processing characteristics such as adhesiveness and binding property on the surface of the overcoat layer.

  Moreover, an organic pigment (organic filler) can be added as a filler to the protective layer of the present invention. Examples of the organic pigment used in the present invention include fine powders such as urea formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin, and spherical particles are particularly preferable. Of these, cross-linked polymethyl methacrylate is particularly effective. Moreover, as addition amount, 0.05-2 parts is preferable with respect to 1 part of resin. The average particle size is preferably 2 to 10 μm. If this average particle diameter exceeds 10 μm, the surface unevenness is too large and the image becomes rough. Conversely, if it is less than 2 μm, the close contact with the head is too good, and there is a concern that the transportability is deteriorated. Moreover, these organic pigments can be used by mixing with other inorganic pigments as required. Examples of these inorganic pigments include inorganic fine powders such as silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium and silica. .

  Examples of the resin used for forming the protective layer in the present invention include a water-soluble resin, an aqueous emulsion, a hydrophobic resin, an ultraviolet curable resin, and an electron beam curable resin. Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose, methoxy cellulose, hydroxy cellulose, etc.), casein, gelatin, polyvinyl pyrrolidone, styrene / maleic anhydride copolymer, diisobutylene / anhydrous. Examples include maleic acid copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether / maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, melamine / formaldehyde resin, urea / formaldehyde resin, and the like. Examples of aqueous emulsion resins or hydrophobic resins include polyvinyl acetate, polyurethane, styrene / butadiene copolymers, styrene / butadiene / acrylic copolymers, polyacrylic acid, polyacrylate esters, vinyl chloride / vinyl acetate. Examples include, but are not limited to, copolymers, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, ethyl cellulose, and ethylene / vinyl acetate copolymers. Among these, water-soluble resins such as polyvinyl alcohol are preferable in view of plasticizer resistance. Moreover, a conventionally well-known crosslinking agent can be used as a water-resistant agent of these water-soluble resins as needed.

  The leuco dyes used in the heat-sensitive color forming layer of the present invention are applied singly or in combination of two or more. As such leuco dyes, those applied to this kind of heat-sensitive material are arbitrarily applied, for example, A leuco compound of a dye such as triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, or indinophthalide is preferably used. Specific examples of such leuco dyes include those shown below.

  3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethyl) Aminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofur Oran, 3-dimethylamino-5,7-dimethylfluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl- 7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, -Diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3′-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-di -N-Butylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anily Fluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- ( 2 ', 4'-dimethylanilino) fluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8' -Methoxy-benzoindolino-spiropyran, 6'-bromo-3'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5 '-Chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) fur Talide, 3- (2′-hydroxy-4′-diethylaminophenyl) -3- (2′-methoxy-5′-methylphenyl) phthalide, 3- (2′-methoxy-4′-dimethylaminophenyl) -3 -(2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilino Fluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5 -Chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) Luolan, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2 -Chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane 3-dibutylamino- 6-Methyl-7-anilinofluorane 3-dipentylamino-6-methyl-7-anilinofluorane 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide , 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4′-butyl Mofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl- N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ′, 5′-benzofluorane, 3-p-dimethylaminophenyl) -3 -{1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2 -Yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene- -Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4 ' -Dimethylamino-2'-methoxy) -3- (1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3- (4'- Dimethylamino-2′-benzyloxy) -3- (1 ″ -p-dimethylaminophenyl-1 ″ -phenyl-1 ″, 3 ″ -butadiene4 ″ -yl) benzophthalide, 3-dimethylamino-6-dimethylamino -Fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2-p-methoxyphenyl} Ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromo Phthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane, and the like.

  As the developer used in the heat-sensitive color developing layer of the present invention, various electron-accepting compounds that cause the leuco dye to develop a color upon contact, an oxidizing agent, or the like is applied. Such a thing is conventionally well-known and the following are mentioned as a specific example, However, It is not necessarily restricted to these.

  4,4′-isopropylidenebisphenol, 4,4′-isopropylidenebis (o-methylphenol), 4,4′-secondary butylidenebisphenol 4,4′-isopropylidenebis (2-tertiarybutylphenol), p -Zinc nitrobenzoate, 1,3,5-tris (4-tertiarybutyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2- (3,4'-dihydroxydiphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide, 4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1, 5-bis (4-hydroxyphenylthio) -5-oxapentane, phthalic acid monobenzyl ester mono Lucium salt, 4,4′-cyclohexylidenediphenol, 4,4′-isopropylidenebis (2-chlorophenol), 2,2′-methylenebis (4-methyl-6-tertiarybutylphenol), 4,4 ′ -Butylidenebis (6-tertiarybutyl-2-methyl) phenol, 1,1,3-tris (2-methyl-4-hydroxy-5-tertiarybutylphenyl) butane, 1,1,3-tris (2- Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4′-thiobis (6-tertiarybutyl-2-methyl) phenol, 4,4′-diphenolsulfone, 4-isopropoxy-4′-hydroxy Diphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide Isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) -propane, N, N'- Diphenylthiourea, N, N′-di (m-chlorophenyl) thiourea, salicylanilide, bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4′-diphenolsulfone, 2,2′-diallyl-4,4′-diphenolsulfone, 3, 4-dihydroxyphenyl-4′-methyldiphenylsulfone, 1-acetyloxy-2-naphtho Zinc acetate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, antipyrine complex of zinc thiocyanate, tetra Bromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol), 4,4′-thiobis (2-chlorophenol) and the like.

  In the heat-sensitive recording material of the present invention, the developer is usually 1 to 20 parts, preferably 2 to 10 parts, relative to 1 part of the color former. The developer can be applied alone or in combination of two or more, and the color former can be applied alone or in combination of two or more.

  In order to produce the thermosensitive recording material of the present invention, when a leuco dye and a developer are bonded and supported on a support, various conventional binders can be used as appropriate. Specific examples thereof include, for example, Can be mentioned.

  Polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, polyacrylic acid soda, polyvinyl Pyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, In addition to water-soluble polymers such as sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / Such as vinyl acetate copolymer Rujon and styrene / butadiene copolymer, styrene / butadiene / latex such as acrylic copolymer.

In the present invention, various heat-fusible substances can be used as the sensitivity improver, and specific examples thereof include, but are not limited to, stearic acid, behenic acid, and the like. Fatty acids such as acids, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzylbiphenyl, terphenyl , Triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, gray Coal carbonate, dibenzyl terephthalate, Dimethyl phthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, 1 , 2-bis (4-methylphenoxy) ethane, 1,4-diphenoxy-2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1, 4-diphenylthio-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) bifer, p- Aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldi Sulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4- Chlorobenzyl) and the like.

  The thermosensitive coloring layer is uniformly dispersed or dissolved in an organic solvent together with a color former, a developer, a binder, and the like, and this is coated on a support and dried, but the coating method is not particularly limited. The dispersed particle size of the color layer coating solution is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. The thickness of the color developing layer depends on the composition of the color developing layer and the application of the heat-sensitive recording material, but is about 1 to 50 μm, preferably about 3 to 20 μm. In addition, various additives used for ordinary heat-sensitive recording paper can be added to the color forming layer coating solution as necessary for the purpose of improving the coatability or the recording characteristics.

  Either acidic paper or neutral paper can be used as the support in the present invention. Further, regarding the release paper made of the neutral paper support and the neutral paper, one having a small amount of calcium is preferable. In this way, the release paper made of neutral paper and neutral paper with a small amount of calcium can be obtained by reducing the ratio of used paper for papermaking. In addition, calcium carbonate is usually used as an internal additive in papermaking of neutral paper, and alkyl ketene dimer or alkenyl succinic anhydride is used as a sizing agent, whereas the internal additive is replaced with talc or clay, Obtained by combining with a neutral rosin sizing agent.

  The recording method of the heat-sensitive recording material of the present invention is not particularly limited depending on the purpose of use, such as a thermal pen, a thermal head, or laser heating.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. Unless otherwise specified, “part” described below means “part by mass”.
The physical properties of the wax were measured as follows.

(Melt viscosity)
Measurements were made at 140 ° C. using a Brookfield viscometer.
(Intrinsic viscosity [η])
Measured according to ASTM D1601.
(density)
It measured according to JIS K6760.
(Melting point)
Measured according to ASTM D3417-75.
(Softening point)
It measured according to JIS K2207.
(Penetration)
It measured according to JIS K2207.

[Synthesis Example 1]
(Synthesis of polyolefin wax (1))
Using a metallocene catalyst, an ethylene / propylene copolymer (polyolefin wax (1)) was synthesized as follows.

A stainless steel autoclave with an internal volume of 2 liters that was sufficiently purged with nitrogen was charged with 930 ml of hexane and 70 ml of propylene, and hydrogen was introduced until the pressure reached 0.10 MPa (gauge pressure). Next, after raising the temperature in the system to 150 ° C., 0.3 mmol of triisobutylaluminum, 0.004 mmol of triphenylcarbenium tetrakis (pentafluorophenyl) borate, (t-butylamido) dimethyl (tetramethyl-η ⁵⁾ Polymerization was initiated by injecting 0.02 mmol of -cyclopentadienyl) silane titanium dichloride (Sigma-Aldrich) with ethylene. Thereafter, only ethylene was continuously supplied to keep the total pressure at 2.9 MPa (gauge pressure), and polymerization was carried out at 150 ° C. for 20 minutes.

After the polymerization was stopped by adding a small amount of ethanol into the system, unreacted ethylene and propylene were purged. The resulting polymer solution was dried overnight at 100 ° C. under reduced pressure. As a result, [η] is 0.23 dl / g, melt viscosity is 750 mPa · s, Mn is 2200, Mw is 6500, density is 925 kg / m ³ , and melting point is 106 ° C. 27.5 g of a metallocene wax having a softening point of 115 ° C. and a penetration of 1 dmm was obtained.

  The above synthesis operation was repeated until the required amount was collected, and the synthesized metallocene wax was melt mixed and then cooled to obtain a polyolefin wax (1).

[Synthesis Example 2]
(Synthesis of polyolefin wax (2))
Using a metallocene catalyst, an ethylene / propylene copolymer (polyolefin wax (2)) was synthesized as follows.

A stainless steel autoclave with an internal volume of 2 liters that was sufficiently purged with nitrogen was charged with 935 ml of hexane and 65 ml of propylene, and hydrogen was introduced until the pressure reached 0.25 MPa (gauge pressure). Next, after raising the temperature in the system to 150 ° C., 0.3 mmol of triisobutylaluminum, 0.004 mmol of triphenylcarbenium tetrakis (pentafluorophenyl) borate, (t-butylamido) dimethyl (tetramethyl-η ⁵⁾ Polymerization was initiated by injecting 0.02 mmol of -cyclopentadienyl) silane titanium dichloride (Sigma-Aldrich) with ethylene. Thereafter, only ethylene was continuously supplied to keep the total pressure at 2.9 MPa (gauge pressure), and polymerization was carried out at 150 ° C. for 20 minutes.

After the polymerization was stopped by adding a small amount of ethanol into the system, unreacted ethylene and propylene were purged. The resulting polymer solution was dried overnight at 100 ° C. under reduced pressure. As a result, [η] is 0.13 dl / g, melt viscosity is 18 mPa · s, Mn is 1100, Mw is 2900, density is 923 kg / m ³ , and melting point is 102 ° C. There was obtained 25.5 g of a metallocene wax having a softening point of 106 ° C. and a penetration of 7 dmm.

  The above synthesis operation was repeated until the required amount was collected, and the synthesized metallocene wax was melt mixed and then cooled to obtain polyolefin wax (2).

  Table 1 shows the physical properties of the polyolefin wax used in the examples and the high wax HW420P which is the polyolefin wax used in the comparative example.

(Production of polyolefin wax emulsion (1))
320 g of polyolefin wax (1) and 80 g of high wax HW2203A were mixed in a SUS container at 140 ° C. with stirring.

  Put 1600 ml of water and 3.0 g of potassium hydroxide in a pressure-resistant homomixer, heat to 140 ° C. and stir at 5000 rpm, and feed 400 g of the above-mentioned polyolefin wax mixture to the above mixer by a gear pump in a molten state at 140 ° C. over 1 hour. did. The mixture was further stirred for 30 minutes and then cooled to room temperature to obtain an aqueous dispersion of polyolefin wax particles. The average dispersed particle size of the polyolefin wax emulsion (1) was 1.2 μm.

(Production of polyolefin wax emulsion (2))
A polyolefin wax emulsion (2) was obtained in the same manner as in the production of the polyolefin wax emulsion (1) except that the polyolefin wax (2) was used instead of the polyolefin wax (1). The average dispersed particle size of the obtained polyolefin wax emulsion (2) was 1.0 μm.

(Production of polyolefin wax emulsion (3))
A polyolefin wax emulsion (3) was obtained in the same manner as in the production of the polyolefin wax emulsion (1) except that a high wax HW420P (Mitsui Chemicals) was used instead of the polyolefin wax (1). The average dispersed particle size of the obtained polyolefin wax emulsion (3) was 1.4 μm.

(Production of copolymer resin emulsion (1))
A separable flask equipped with a stirrer and a reflux condenser was charged with 195 parts of deionized water and 0.3 part of sodium dodecylbenzenesulfonate, and the temperature was raised to 70 ° C. after substitution with nitrogen gas. After the temperature increase, 1.0 part of potassium persulfate was added, and then a vinyl monomer emulsion having the following composition was continuously added over about 4 hours, and then the temperature was raised to 80 ° C. and held for 2 hours for polymerization. Completed. After completion, the mixture was neutralized by adding ammonia water, and after maintaining the temperature for 1 hour for hydration and swelling / softening treatment, the pH was adjusted to about 8.0 by cooling to room temperature. A copolymer resin emulsion (1) having a solid content of about 30% was obtained. The resulting copolymer emulsion had a glass transition temperature (Tg) of 16.5 ° C.
Vinyl monomer emulsion composition Acrylonitrile 30.0 parts n-butyl acrylate 50.0 parts Methacrylic acid 10.0 parts 2-Hydroxyethyl methacrylate 10.0 parts n-dodecyl mercaptan 0.5 parts Deionized water 40 .0 part sodium dodecylbenzenesulfonate 0.5 part

(Glass-transition temperature)
The glass transition temperature was determined by the Fox equation (Bull. Am. Phys. Soc., Vol. 1, No. 3, p. 123 [1956]).

[Example 1]
10 g of the polyolefin wax emulsion (1) was added to 100 g of the copolymer resin emulsion (1), and then sufficiently stirred and mixed to prepare a resin emulsion. Next, 25 g of a 60% dispersion of kaolinite clay (manufactured by Engelhardt: UW90) and 25 g of water are added to this preparation as a filler, mixed uniformly, and then dried on a commercially available surface-untreated heat-sensitive word processor paper at 3 g / After coating with a bar coater to m ² , drying (forced drying at 60 ° C. for 30 seconds, followed by curing in a 20 ° C./60% RH atmosphere for 24 hours) gave a heat-sensitive recording material.
The obtained thermal recording material was evaluated by the following methods. The evaluation results are shown in Table 2.

(I) Running stability Using a thermal printer (manufactured by Okura Electric Co., Ltd., TH-PMD), a pattern image of solid black recording was created under the following conditions.
The surface condition of the protective layer was comprehensively evaluated.
Applied voltage: 24V
Pulse width: 1.74 ms
Applied energy: 0.34 mj / dot ○: No sound, no head contamination, and the surface state of the protective layer is good. Smooth paper feeding.
Δ: Some noise, but no head contamination, and the surface condition of the protective layer is good. Paper feed
mousse.
×: Cracking and loud sound. Head dirt is seen and the surface of the protective layer is rough. paper
There is also an obstacle to feeding.

(Ii) Water resistance Using a Gakushin friction fastness tester (no load), apply a heat-sensitive recording surface developed by applying a non-colored part and a 140 ° C heat block for 1 second to a gauze soaked in water. The condition was observed by rubbing 20 times.
○: No change.
Δ: Scratched marks are observed.
X: The heat-sensitive recording layer is missing.

(Iii) Plasticizer resistance An image is created under the same conditions as above, and a transparent type polyvinyl chloride adhesive tape for electrical insulation (manufactured by Nitto Denko) is pasted on the image area and peeled off after 24 hours at 40 ° C. The density of the non-tape-attached part and the tape-attached part was measured with a Macbeth densitometer, and the concentration retention rate (%) was calculated by the following formula. (The higher the value, the better).
Concentration retention rate (%) = (concentration of tape application area ÷ density of non-tape application area)
× 100

(Iv) Stability of Protective Layer Compound Liquid The state of the protective layer compound liquid after 24 hours at 40 ° C. was comprehensively observed. (Thickening, gelling,
Separation)

[Example 2]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the addition amount of the polyolefin wax emulsion (1) was changed to 20 g and the addition amount of water was changed to 15 g.

[Example 3]
Thermal recording was performed in the same manner as in Example 1 except that kaolinite clay was changed to 12 g of a 50% dispersion of finely divided silica (manufactured by Mizusawa Chemical: P-527) and the amount of water added was changed to 38 g. Obtained material.

[Example 4]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the polyolefin wax emulsion (1) was changed to the polyolefin wax emulsion (2).

[Comparative Example 1]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the polyolefin wax emulsion (1) was changed to a 20% solid content concentration zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd .: F115 fine particle type).

[Comparative Example 2]
A heat-sensitive recording material was obtained in the same manner as in Example 2 except that the polyolefin wax emulsion (1) was changed to the polyolefin wax emulsion (3).
Table 2 shows the evaluation results of the heat-sensitive recording materials obtained in Examples 1 to 4 and Comparative Examples 1 and 2.

  The heat-sensitive recording material of the present invention has particularly excellent performance in terms of slipperiness due to the use of a specific polyolefin wax as a lubricant in the protective layer. Therefore, when this heat-sensitive recording material is applied, high running stability, glossiness, water resistance and plasticizer resistance can be maintained, which is industrially useful.

Claims (2)

A heat-sensitive recording material in which a heat-sensitive color-developing layer that is colored by heat is provided on a support, and a protective layer is provided on the upper surface thereof, and the number-average molecular weight measured by gel permeation chromatography (GPC) in the protective layer (Mn) is in the range of 400 to 5,000, differential scanning calorimeter (DSC)
The crystallization temperature measured with a differential scanning calorimeter (DSC) has a melting point measured in the range of 65 to 130 ° C., a density (D) measured by a density gradient tube method in a range of 850 to 980 kg / m ^3. (Tc (° C.), measured at a temperature drop rate of 2 ° C./min) and the density (D (kg / m ³ )) are represented by the following formula (I)
0.501 × D-366 ≧ Tc (I)
Containing a polyolefin wax which satisfies,
The polyolefin wax is an ethylene homopolymer produced by a metallocene catalyst or a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms,
The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyolefin wax measured by gel permeation chromatography (GPC) is in the range of 1.1 to 5.0. A heat-sensitive recording material. The polyolefin wax is heat-sensitive recording material of claim 1 Symbol mounting characterized by comprising the emulsion dispersed polyolefin wax emulsion.