Use of a composition for preparing a near IR absorbing material, and mouldings containing this material

This invention relates to the use of a near-IR absorbent mass containing at least one thiourea compound and at least one copper compound and or lead compound for the production of a material in the near-IR region after heat treatment, and to a shaped body containing this mass or material.

The materials absorbing in the near IR have been specially developed in recent years. These materials are widely used in practice, for example as light-sensitive materials in which a semiconductor laser with a wavelength in the near IR range, etc. is used as a light source; as information recording materials such as optical recording disks; as optical materials such as filters and films for the near IR, etc; as a material for shielding thermal rays.

A chromium-cobalt complex is described in JP-A-42269/1985 as known materials absorbing in the near IR; a ThiolNickel complex in JP-A-21294/1985; an anthraquinone derivative in JP-A-115958/1986; a new squarylium compound with a maximum wavelength of 700-800 nm in JP-A-218551/1986. In "In the near IR absorbing dye" (Kagakukogyo 43, May 1959) nitroso compounds, their metal complexes, polymethine dyes (cyanine dyes), thiol-cobalt complexes, thiol-platinum complexes, thio-palladium complexes, phthalocyanine dyes, triarylmethane dyes, diimmonium dyes, immunononium dyes, immononium dyes, immunondyes and the like.

The previous organic type materials absorbing in the near IR have the disadvantage that the durability is inferior; that is, the initial properties deteriorate under the influence of environmental conditions or over time. On the other hand, the complex-type materials absorbing in the near IR have superior durability, but they have the disadvantage that because of the absorption of the visible light, the materials are highly colored, which makes the materials of limited use. Each material has an absorption maximum at a certain wavelength, but has almost no absorption capacity at other wavelengths. In the case of a recording material in which the above material is used and, for example, a laser light with a wavelength in the near IR is used as the light source, it is necessary that the laser wavelength match the absorption maximum of the material. Because the laser wavelength and the absorption material wavelength are limited, the combination possibilities in which the laser wavelength and the absorption material wavelength match are very small. Furthermore, such combinations are practically non-existent, taking into account the absorbency, durability, color, cost, etc. of the recording material. These materials are therefore of limited use.

JP-A-141,639 / 1976 describes a thermographic recording material which (A) is a salt of a metal selected from tin, cobalt, nickel and lead and an acid selected from silicon, boric and phosphorus oxyacids and organic carboxylic acids with 12 or less Carbon atoms; (B) a thiosulfate of a metal less noble than tin and (C) an organic compound containing the thiourea unit and at least one reactive hydrogen atom. When using the material in a thermofax copier, you get a sharp brown copy with good contrast.

GB-A-1 202 881 describes photosensitive compositions comprising a silver halide consisting at least in part of silver bromide, copper i-iodide and an organic halogen acceptor, which is a compound having a thiourea group. These compositions are useful for making photographic materials.

The present invention has for its object to provide a near-IR absorbing material and a near-IR absorbent shaped body which develop a color to a small extent when heated, are of high durability and have a uniform absorption in the near IR range of 700-2000 nm wavelength.

These objects are achieved by the use of a mass for the production of a material which absorbs in the near IR after heat treatment and which comprises at least one thiourea compound of the general formula (I)<chemistry id="chem0001" num="0001"><img file="EP0346772B1_D0001.tif" /></chemistry> (wherein R₁, R₂ and R₃ each represent a hydrogen atom, an alkyl, cycloalkyl, aryl, aralkyl alkenyl group, or monovalent radical of a 5 or 6-membered ring, where each group can be substituted by at least one substituent, or R₁ and R₂ or R₂ and R₃ together can form a ring) and also contains at least one copper and / or lead compound.

The near infrared absorbing material of the present invention comprises the reaction product obtained by the heat treatment of the mass. The shaped body according to the invention comprises the material according to the invention, obtainable by heat treatment of the mass.

The choice of the thiourea compounds of the general formula (I) is not particularly restricted, for example the following can be used:<chemistry id="chem0002" num="0002"><img file="EP0346772B1_D0002.tif" /></chemistry>    1-ethyl-3-phenylthiourea<chemistry id="chem0003" num="0003"><img file="EP0346772B1_D0003.tif" /></chemistry>    1,3-diphenylthiourea<chemistry id="chem0004" num="0004"><img file="EP0346772B1_D0004.tif" /></chemistry>    1,3-diethylthiourea<chemistry id="chem0005" num="0005"><img file="EP0346772B1_D0005.tif" /></chemistry>    1-ethyl-3-p-chlorophenylthiourea<chemistry id="chem0006" num="0006"><img file="EP0346772B1_D0006.tif" /></chemistry>    1-ethyl-3- (2-hydroxyethyl) thiourea<chemistry id="chem0007" num="0007"><img file="EP0346772B1_D0007.tif" /></chemistry>    1- (2-thiazolyl) -3-phenylthiourea<chemistry id="chem0008" num="0008"><img file="EP0346772B1_D0008.tif" /></chemistry>    1,3-distearylthiourea<chemistry id="chem0009" num="0009"><img file="EP0346772B1_D0009.tif" /></chemistry>    1,3-dibehenylthiourea<chemistry id="chem0010" num="0010"><img file="EP0346772B1_D0010.tif" /></chemistry>    1-ethylthiourea<chemistry id="chem0011" num="0011"><img file="EP0346772B1_D0011.tif" /></chemistry>    1-p-bromophenyl-3-phenylthiourea<chemistry id="chem0012" num="0012"><img file="EP0346772B1_D0012.tif" /></chemistry>    1- (2-thiophenyl) -3-phenylthiourea<chemistry id="chem0013" num="0013"><img file="EP0346772B1_D0013.tif" /></chemistry>    1,3-bis (hydroxyethyl) thiourea<chemistry id="chem0014" num="0014"><img file="EP0346772B1_D0014.tif" /></chemistry>    1-p-aminophenyl-3-phenylthiourea<chemistry id="chem0015" num="0015"><img file="EP0346772B1_D0015.tif" /></chemistry>    1-p-nitrophenyl-3-phenylthiourea<chemistry id="chem0016" num="0016"><img file="EP0346772B1_D0016.tif" /></chemistry>    1-p-hydroxyphenyl-3-phenylthiourea<chemistry id="chem0017" num="0017"><img file="EP0346772B1_D0017.tif" /></chemistry>    1,3-di-m-chlorophenylthiourea<chemistry id="chem0018" num="0018"><img file="EP0346772B1_D0018.tif" /></chemistry><chemistry id="chem0019" num="0019"><img file="EP0346772B1_D0019.tif" /></chemistry><chemistry id="chem0020" num="0020"><img file="EP0346772B1_D0020.tif" /></chemistry>    1-methyl-3-p-hydroxyphenylthiourea<chemistry id="chem0021" num="0021"><img file="EP0346772B1_D0021.tif" /></chemistry><chemistry id="chem0022" num="0022"><img file="EP0346772B1_D0022.tif" /></chemistry>    1 m nitrophenylthiourea<chemistry id="chem0023" num="0023"><img file="EP0346772B1_D0023.tif" /></chemistry>    1-p-nitrophenylthiourea<chemistry id="chem0024" num="0024"><img file="EP0346772B1_D0024.tif" /></chemistry>    1-p-aminophenylthiourea<chemistry id="chem0025" num="0025"><img file="EP0346772B1_D0025.tif" /></chemistry>    1,3-dimethylthiourea<chemistry id="chem0026" num="0026"><img file="EP0346772B1_D0026.tif" /></chemistry>    1,3-dicyclohexylthiourea<chemistry id="chem0027" num="0027"><img file="EP0346772B1_D0027.tif" /></chemistry>    1-phenyl-3-p-chlorophenylthiourea<chemistry id="chem0028" num="0028"><img file="EP0346772B1_D0028.tif" /></chemistry>    1-phenyl-3-p-methoxyphenylthiourea<chemistry id="chem0029" num="0029"><img file="EP0346772B1_D0029.tif" /></chemistry>    1.1-diphenylthiourea<chemistry id="chem0030" num="0030"><img file="EP0346772B1_D0030.tif" /></chemistry>    1,1-dibenzyl-3-phenethylthiourea<chemistry id="chem0031" num="0031"><img file="EP0346772B1_D0031.tif" /></chemistry>    1-phenyl-3- (2-hydroxyethyl) thiourea

The copper compound according to the invention is a copper compound of the formula (II)<maths id="math0001" num="(II)"><math display="block"><mrow><msub><mrow><mtext>(R - X)</mtext></mrow><mrow><mtext>n</mtext></mrow></msub><mtext> C u</mtext></mrow></math><img file="EP0346772B1_D0032.tif" /></maths> wherein R is a hydrogen atom, an alkyl, cycloalkyl, aryl, aralkyl group or a heterocyclic radical (where each group or the radical can be substituted by at least one substituent), X -COO, -SO₄, -SO₃, -PO₄, or -O means n is an integer from 1 to 4.

The choice of the copper compounds of the general formula (II) according to the invention is not particularly restricted, for example use the following: Copper stearate, copper palmitate, copper oleate, copper behenate, copper laurate, copper caprate, copper capronate, copper valerianate, copper isolactate, copper lactate, copper propionate, copper acetate, copper format, copper hydroxide, copper benzoate, copper o-toluylate, copper m-toluylate, copper p-toluylate p-tert-butyl benzoate, copper o-chlorobenzoate, copper m-chlorobenzoate, copper p-chlorobenzoate, copper dichlorobenzoate, copper trichloro benzoate, copper p-bromobenzoate, copper p-iodobenzoate, copper p-phenyl benzoate, Copper-o-benzoylbenzoate, copper-p-nitrobenzoate, copper anthranilate, copper-p-aminobenzoate, copper oxalate, copper malonate, copper succinate, copper glutarate, copper adipate, copper pimelate, copper suberate, copper azelate, copper sebacinate, copper phthalate, copper monoaphthalene phthalate, copper naphthalene phthalate, copper naphthalenate, 2-carboxylate, copper 4-cyclohexyl lactate, copper diethyldithiocarbamate, copper gluconate, diethoxy copper, di-isopropoxy copper, di-n-butoxy copper, Copper octylate, copper alkylbenzenesulfonate, copper p-toluenesulfonate, copper naphthalene sulfonate, copper naphthylamine sulfonate, copper n-dodecylbenzenesulfonate, copper dodecyl sulfate, copper 2,5-dimethylbenzenesulfonate, copper-2-carbomethoxy-5-methylbenzylphosphate Copper di-2-ethylhexyl phosphate, copper isodecyl phosphate, and the like.

The lead compound according to the invention is a lead compound of the formula (III)<maths id="math0002" num="(III)"><math display="block"><mrow><msub><mrow><mtext>(R - X)</mtext></mrow><mrow><mtext>n</mtext></mrow></msub><mtext> Pb</mtext></mrow></math><img file="EP0346772B1_D0033.tif" /></maths> wherein R is a hydrogen atom, an alkyl, cycloalkyl, aryl, aralkyl group or a heterocyclic radical (where each group or the radical can be substituted by at least one substituent), X -COO, -SO₄, -SO₃, -PO₄, or -O means, n is an integer from 1 to 4.

The choice of the lead compounds of the general formula (III) according to the invention is not particularly restricted, for example use the following: Lead stearate, lead palmitate, lead violate, lead behenate, lead laurate, lead caprate, lead capronate, lead allianate, lead isolate, lead lactate, lead propionate, lead acetate, lead formate, lead hydroxide, lead benzate, lead-o-toluylate, lead-m-toluylate, lead p-tert-butyl benzoate, lead o-chlorobenzoate, lead m-chlorobenzoate, lead p-chlorobenzoate, lead dichlorobenzoate, lead richlor benzoate, lead p-bromobenzoate, lead p-iodobenzoate, lead p-phenyl benzoate, lead o-benzoyl benzoate, lead p-nitrobenzoate, Lead thranilate, lead p-aminobenzoate, lead oxalate, lead mononate, lead succinate, lead glutarate, lead adipate, lead pimelate, lead tuberate, lead acelate, lead sebacinate, lead phthalate, lead monoester phthalate, lead naphthenate, lead naphthalene carbonate, 4 Lead gluconate, diethoxy lead, di-isopropoxy lead, di-n-butoxy lead, lead octylate, lead alkylbenzenesulfonate, lead p-toluenesulfonate, lead naphthalenesulfonate, Lead naphthylamine sulfonate, lead n-dodecylbenzenesulfonate, lead dodecyl sulfate, lead 2,5-dimethylbenzenesulfonate, lead 2-carbomethoxy-5-methylbenzenesulfonate, lead α-naphthylphosphate, lead arylphosphate, lead ilaurylphosphate, lead-ilaurylphosphate, 2-lead-ethylphosphate, phosphate, lead-lauryl-phosphate-2-phosphate, .

In formulas I, II and III, alkyl, alkenyl, alkoxy etc. can be straight-chain or branched. Preferably alkyl is C₁-C₃₀ alkyl, especially C₁-C₂₅ alkyl. Examples are methyl, ethyl, n- and i-propyl, butyl, stearyl or behenyl.

Cycloalkyl is preferably cyclopentyl or cyclohexyl.

Aryl is preferably phenyl or naphthyl, aralkyl is preferably phenyl-C₁-C₄-alkyl, such as benzyl or phenylethyl.

Alkenyl is preferably C₂-C₆ alkenyl, especially C₂-C₄ alkenyl.

The heterocyclic radicals are preferably 5- or 6-membered rings with one or more oxygen, sulfur or nitrogen heteroatoms, such as thiazolyl, thienyl, furyl, pyrrolidinyl, pyrrolyl, morpholinyl, piperazinyl, piperidinyl or pyridinyl. If R₁ and R₂ or R₂ and R₃ together form a ring, they are preferably ethylene, propylene or butylene.

Preferred substituents of the radicals present in the formulas I, II and III are straight-chain or branched C₁-C₁₈-alkyl (such as methyl, ethyl, n- and i-propyl, n-, i- and t-butyl, dodecyl etc.), C₁-C₄ alkoxy, hydroxy, halogen (F, C1, Br, J), nitro, amino, phenyl, cyclopentyl, cyclohexyl, benzoyl, acetyl.

Either the above thiourea compound or the above copper or lead compound hardly absorbs near IR light or only a certain wavelength. Heat treatment of the thiourea compound or the copper or lead compound has no effect on absorption in the near IR. But the mixture of this thiourea compound and this copper and / or lead compound absorbs near IR light strongly and evenly after its heat treatment.

Without heat treatment, the mixture of a thiourea compound of the general formula (I) and at least one compound from the group of the compounds of the general formula (II), the compounds of the general formula (III), copper and lead acetylacetonates, chlorophyll copper and lead and chlorophyllin copper and lead almost no near IR light.

If one treats the mass or the shaped bodies containing this mass completely or partially (in sections) by supplying thermal energy, the heated part strongly absorbs the near IR light. The heated part does not absorb light in the visible wavelength range and produces a latent image (a pattern created by heating).

Therefore, using the above phenomenon, one can produce a detector for the pattern generated by heating and in combination with a suitable developing device, a recording paper.

Because the material of the present invention, which is obtained by the heat treatment of the composition containing a mixture of a thiourea compound and a copper and / or lead compound, strongly absorbs the light in the near IR range, it can be used in the manufacture of a near IR light detector and in the manufacture of the means for the laser beam recording system.

The strength of the absorption in the near IR can be adjusted by the type and the mixing ratio of thiourea compound and copper and / or lead compound, heating temperature and time, etc.

The mass is made by mixing the thiourea compound and the copper and / or lead compound in an appropriate mixing ratio, or by mixing the thiourea compound, the copper and / or lead compound, a binder, pulp, wood pulp, thermoplastic resin powder, etc. and optionally Additives such as dyes etc. mixed.

Furthermore, the mass can be prepared by dissolving the mixture of all raw materials in a suitable solvent or a suitable dispersion, or by dissolving all raw materials except for binder, dye, etc. in a solvent in which binder, colorant, etc. are dispersed or are dissolved.

The mass can be, for example, a coating mass, filler, etc. The mixing ratio, the mass content in the molded body and the addition amount of other substances are determined such that the thiourea compound and the copper and / or lead compound are brought into contact as solids or as a melt or as a mixture of solid and melt when heated.

The molded article according to the invention comprises a mass obtainable by heat treatment which contains the thiourea compound and the copper and / or lead compound, or a material which absorbs in the near IR and is obtained by the heat treatment of the mass. The process for producing this shaped body is carried out by:<ul id="ul0001" list-style="none" compact="compact"><li>(a) shaping a mixture of the shaped body raw materials and the near IR absorbing material according to the invention, or</li><li>(b) applying or impregnating a dispersed sludge of the material according to the invention to the shaped body raw material by means of an atomizing, coating or printing machine.</li></ul>

The shaped body is produced by producing a film, a sheet or a rod from cellulose, wood pulp, fiber, thermoplastic resin, etc. in a known manner, for example by weaving, sheet formation, heat-forming, etc., and if necessary treating it further.

The heat treatment to achieve absorbance in the near IR is not particularly limited. All heat treatments that involve the transfer of thermal energy to achieve absorption in the near IR due to the reaction of the thiourea compound with the copper or lead compound can be used in accordance with the invention. The heating can be carried out, for example, using an electric heater, induction heater, film extruder, etc., thermal head, semiconductor laser; IR lamp and the like.

The heat treatment is carried out under any atmosphere, for example an air atmosphere, an inert gas atmosphere, etc., usually under an air atmosphere.

The heating temperature is usually 40-400 ° C, preferably 50-350 ° C. The heating time is in the range of a few milliseconds to a few ten minutes.

Uniform mixing by means of a mixer, for example a whisk, by stirring and swiveling is preferred because this leads to uniform heat transfer and a high reaction rate because of the increasing frequency of contact between the materials.

The mixing ratio of thiourea compound, copper and / or lead compound differs depending on the type of these compounds, but 0.01-50 parts by weight, preferably 0.1-10 parts by weight of the thiourea compound, based on 1 part by weight of the Copper and / or lead compound are generally used.

As mentioned above, the mixture takes from the thiourea compound of the general formula (I) and from at least one compound from the group copper and lead hydroxide, copper compound of the general formula (II), lead compound of the general formula (III), copper and lead acetylacetonate , Chlorophyll copper and lead, and After heat treatment, chlorophyllin copper and lead uniformly illuminate near IR light over the entire range of 700 - 2000 nm. The reason for the above fact is not clear.

As can be seen from the following examples and comparative examples, neither the thiourea compound nor the above copper and / or lead compound absorbs near IR light strongly and uniformly over the entire range of 700-2000 nm after heat treatment. The mixture of the thiourea compound of the general formula (I) and the above copper and / or lead compound without heat treatment likewise does not absorb any near IR light strongly and uniformly. Therefore, it is believed that when the mixture is heat-treated, a reaction occurs between the thiourea compound represented by the general formula (I) and the above copper and / or lead compound, thereby forming a complex.

The invention is illustrated by the following examples. As an abbreviation for parts by weight, "parts" is used.

[* Example 1] (comparative example)

The thiourea compounds and copper compounds of Nos. 1, 3 and 5 of those in Table 1 were wet-ground in an attritor to a particle size of approximately 3 μ.

Solution A

<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Thiourea compound of No. 1, 3 or 5</entry><entry namest="col2" nameend="col2" align="right">20 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">30th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">   total</entry><entry namest="col2" nameend="col2" align="right">100 Parts</entry></row></tbody></tgroup></table></tables>

Solution B

<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Copper connection of No. 1, 3 or 5</entry><entry namest="col2" nameend="col2" align="right">20 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">30th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">   total</entry><entry namest="col2" nameend="col2" align="right">100 Parts</entry></row></tbody></tgroup></table></tables>

50 Parts of solution A and 50 parts of solution B were mixed together to prepare a coating composition.

This coating composition was applied in a coating amount of 5 g / m onto a high-quality paper with a weight of 60 g / m by means of the Meyerbar device and dried. A recording sheet was obtained. All of the recording sheets obtained are white to pale blue, and turn pale green when they are touched with a metal plate from a surface temperature of 150 ° C for 5 seconds. For each colored part, the absorption values ​​of the near IR light at 800, 900, 1000, 1500 and 2000 nm wavelength are on average more than 80% and are therefore high.

The heat sensitive printing was carried out by a heat sensitive bar code printer (BW-100T, manufactured by Mekano System Co., Ltd.). In each case, a pale green bar code pattern was printed on each of the sheets.

This pattern is readable by a bar code slip reader (MS-Ba-Dec 230, manufactured by Mekano System Co., Ltd.) using the light of a semiconductor laser as a reading light source.

Example 2

Based on the combinations No. 1 - 23 in Table 1, 5 parts of a thiourea compound and 5 parts of a copper compound were mixed in a porcelain crucible. 10 parts of the mixture were heat-treated in an electric furnace at 150 ° C for 15 seconds.

The pale-colored powder product obtained was fixed in a certain thickness on high-quality paper.

The reflectance of the surface was measured with the spectrophotometer (UVID EC-590, manufactured by Japan Spectroscopic Co., Ltd.) with respect to the reflection spectrum of the near IR range in the wavelength range of 800 - 2500 nm.

Absorbance in the near IR is presented as the average of the absorption values, this absorption value being the difference between 100% and the reflectance at the wavelengths of 800, 900, 1000, 1500 and 2000 nm. Here ⓞ shows an average value of at least 80%, ○ an average value of at least 60%, Δ an average value of at least 30%, and X an average value of less than 30%.

The material with an average value of at least 30% means a material in the near IR absorbing according to the invention. The near IR absorption capabilities of the materials according to the invention in Nos. 1-23 of Table 1 show an average value of at least 60%.

Comparative Example 1

Each of the thiourea compounds or copper compounds in Table 2 was heat-treated under the same conditions as in Example 2 and applied to the preparation of the product. The near IR reflectance spectrum of a product obtained was measured, and the near IR absorbance was evaluated in the same manner as in Example 2. All absorption capabilities in the near IR are less than 30%, as can be seen from Table 2.

The change in absorptivity in the near IR in the separate heat treatment of the individual components, the mixture without heat treatment, and the mixture of a thiourea compound and a copper compound after heat treatment is illustrated in Figure 1. In Figure 1, 1,3-diphenylthiourea is used as the thiourea compound and copper p-chlorobenzoate is used as the copper compound.

No. 1 and No. 4 of Comparative Example 1 (separate heat treatment) No. 1 of Example 1 mixture without heat treatment) and No. 1 of Example 2 (heat treatment of the mixture) are in the range of 800 - with respect to the near IR reflection spectra 2000 nm compared.

From Figure 1 it can be seen that the absorption capacity of the heated mixture of 1,3-diphenylthiourea and copper p-chlorobenzoate (at No. 1 of Example 2) in the near IR is considerably higher than that of the separately heated components or that Mixture without heat treatment; that is, the near IR absorptivity of No. 1 of Example 2 is more than 90% in the whole measurement wavelength range.

Example 3

The following compositions were prepared with each of the thiourea compounds and copper compounds of Nos. 24-32 of Table 3:

Solution A

<tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Thiourea compound</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">25th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">125 Parts</entry></row></tbody></tgroup></table></tables>

Solution B

<tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Copper connection</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">25th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">125 Parts</entry></row></tbody></tgroup></table></tables>

The solutions of the above compositions were individually milled to a particle size of 1 micron in an attritor. The solutions were mixed together in the ratio shown in Table 3 to obtain a coating composition. The coating composition obtained was applied in a coating amount of 3.0 g / m (solid content) to a high-class paper of 50 g / m and dried to obtain a recording sheet.

This recording sheet was pressed for 5 seconds under a pressure of 10 g / m 2 against a plate heated to 150 ° C. (heat-treated). A near IR absorbing recording sheet was obtained.

The absorbance of the obtained recording sheet was measured in the same manner as in Example 2, and the background color of the coating surface and the resistance of the IR absorbance to heat, moisture, and light were determined as follows, and the results are summarized in Table 3.

[Remarks]

Background color

The reflectance of the coating surface after the heat treatment is measured with a Macbeth density meter (RD-914, use of the amber filter).

Heat resistance

One sheet is left in the oven at 60 ° C for 24 hours. Then the IR reflectance of the sheet is measured with a spectrophotometer (at a wavelength of 1000 nm).

Resistance to heat is rated as a residual percentage of near IR absorbency using the following formula.<maths id="math0003" num=""><math display="block"><mrow><mtext>Remaining percent = </mtext><mfrac><mrow><mtext>100 - reflectance after heat treatment</mtext></mrow><mrow><mtext>100 - reflectance before heat treatment</mtext></mrow></mfrac><mtext>x 100 </mtext><mfenced open="(" close=")"><mrow><mtext>%</mtext></mrow></mfenced></mrow></math><img file="EP0346772B1_D0034.tif" /></maths>

Resistance to humidity

A sheet is left at 40 ° C and 90% relative humidity. After 24 hours. the IR reflectance of the sheet was measured with a spectrophotometer (at a wavelength of 1000 nm). Resistance to atmospheric humidity is evaluated as a residual percentage of the near IR absorption capacity using the following formula.<maths id="math0004" num=""><math display="block"><mrow><mtext>Remaining percent = </mtext><mfrac><mrow><mtext>100 - reflectance after wet storage</mtext></mrow><mrow><mtext>100 - reflectance before wet storage</mtext></mrow></mfrac><mtext>x 100 </mtext><mfenced open="(" close=")"><mrow><mtext>%</mtext></mrow></mfenced></mrow></math><img file="EP0346772B1_D0035.tif" /></maths>

Lightfastness

A sheet is irradiated with the light of a fade-o-meter for 6 hours. The IR reflectance of the sheet is measured with a spectrophotometer (at a wavelength of 1000 nm). The resistance to light is evaluated as a residual percentage of near IR absorption by the following formula.<maths id="math0005" num=""><math display="block"><mrow><mtext>Remaining percent = </mtext><mfrac><mrow><mtext>100 - reflectance after light irradiation</mtext></mrow><mrow><mtext>100 - reflectance before light irradiation</mtext></mrow></mfrac><mtext>x 100 </mtext><mfenced open="(" close=")"><mrow><mtext>%</mtext></mrow></mfenced></mrow></math><img file="EP0346772B1_D0036.tif" /></maths>

Comparative Example 2

The dispersion A containing the thiourea compound or the dispersion B containing the copper compound used in Example 3 was separately applied in the same manner as in Example 3, dried, and then heat-treated to prepare a product. The near IR absorbance of the product was measured.

For the sheets on which a mixture of the thiourea compound and the copper compound were applied and which had been dried, heat treatment leads to a sheet with a high absorption capacity in the near IR, as can be seen from Table 3. This high IR absorption capacity is almost not reduced under the influence of heat, moisture and light and it is surprisingly stable against handling and changes in environmental conditions. The surface of this sheet turns a little gray, but the sheet does not experience any striking changes in color. The sheet on which either the thiourea compound or the copper compound was applied and which was dried did not have near IR absorbency in the heat treatment, and therefore the stability of the IR absorbency during storage was not checked.<tables id="tabl0005" num="0005"><img file="EP0346772B1_D0037.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP0346772B1_D0038.tif" /></tables>

[* Example 4] (comparative example)

Each of the thiourea compounds and the lead compounds described in Nos. 1, 3 and 5 of Table 4 was wet milled to a particle size of approximately 3 µ in an attritor.

Solution A

<tables id="tabl0007" num="0007"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Thiourea compound of No. 1, 3 or 5</entry><entry namest="col2" nameend="col2" align="right">20 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">30th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">   total</entry><entry namest="col2" nameend="col2" align="right">100 Parts</entry></row></tbody></tgroup></table></tables>

Solution B

<tables id="tabl0008" num="0008"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Lead compound of No. 1, 3 or 5</entry><entry namest="col2" nameend="col2" align="right">20 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">30th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">   total</entry><entry namest="col2" nameend="col2" align="right">100 Parts</entry></row></tbody></tgroup></table></tables>

50 Parts of solution A and 50 parts of solution B were mixed together to prepare a coating composition.

This coating composition was applied in a coating amount of 5 g / m onto a high-quality paper with a weight of 60 g / m by means of the Meyerbar device and dried. A recording sheet was obtained. All of the recording sheets obtained are white to pale blue and turn pale green when touched with a metal plate from a surface temperature of 150 ° C for 5 seconds. For each colored part, the absorption values ​​of the near IR light at 800, 900, 1000, 1500 and 2000 nm wavelength are on average more than 80% and are therefore high.

The heat sensitive printing was carried out by a heat sensitive bar code printer (BW-100T, manufactured by Mekano System Co., Ltd.). In each case, a pale green bar code pattern was printed on each of the sheets.

This pattern is readable by a bar code reader (MS-Ba-Dec 230, manufactured by Mekano System Co., Ltd.) using the light of a semiconductor laser as a reading light source.

Example 5

Based on the combinations No. 1 - 23 in Table 4, 5 parts of a thiourea compound and 5 parts of a lead compound were mixed in a porcelain crucible. 10 parts of the mixture were heat-treated in an electric furnace at 150 ° C for 15 minutes.

The pale-colored powder product obtained was fixed in a certain thickness on high-quality paper.

The reflectance of the surface was measured in the same manner as in Example 2.

The near IR absorptivity is shown in the same manner as in Example 2. The near ones. IR absorption capabilities of the materials according to the invention in Nos. 1-23 of Table 4 show an average value of at least 60%.

Comparative Example 3

Each of the thiourea compounds or lead compounds in Table 5 was heat-treated under the same conditions as in Example 5 and applied to the production of the product. The near IR reflectance spectrum of a obtained product was measured, and the near IR absorbance was evaluated in the same manner as in Example 5. All absorption capabilities in the near IR are less than 30%, as can be seen from Table 5.

The change in absorptivity in the near IR in the separate heat treatment of the individual components, the mixture without heat treatment, and the mixture of a thiourea compound and a lead compound after heat treatment is illustrated in Figure 2. In Figure 2, 1,3-diphenylthiourea is used as the thiourea compound and lead p-chlorobenzoate is used as the lead compound. No. 1 and No. 4 of Comparative Example 3 (separate heat treatment) No. 1 of Example 4 (mixture without heat treatment) and No. 1 of Example 5 (heat treatment of the mixture) are compared with respect to the near IR reflection spectra in the range of 800-2000 nm.

From Figure 2 it can be seen that the absorption capacity of No. 1 of Example 5 in the near IR in the heated mixture of 1,3-diphenylthiourea and lead-p-chlorobenzoate is considerably higher than that of the separately heated components or than that of the mixture without Heat treatment; that is, the near IR absorptivity of No. 1 of Example 5 is more than 90% in the whole measurement wavelength range.

Example 6

The following compositions were prepared with each of the thiourea compounds and lead compounds of Nos. 24-32 of Table 6.

Solution A

<tables id="tabl0009" num="0009"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Thiourea compound</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">25th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">125 Parts</entry></row></tbody></tgroup></table></tables>

Solution B

<tables id="tabl0010" num="0010"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Lead compound</entry><entry namest="col2" nameend="col2" align="right">50 Parts</entry></row><row><entry namest="col1" nameend="col1" align="left">10% aqueous solution of polyvinyl alcohol</entry><entry namest="col2" nameend="col2" align="right">25th Parts</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">water</entry><entry namest="col2" nameend="col2" align="right">125 Parts</entry></row></tbody></tgroup></table></tables>

The solutions of the above compositions were individually milled to a particle size of 1 micron in an attritor. The solutions were mixed together in the ratio shown in Table 6 to obtain a coating composition. The coating composition obtained was applied in a coating amount of 3.0 g / m (solid content) to a high-class paper of 50 g / m and dried to obtain a recording sheet.

This recording sheet was pressed for 5 seconds under a pressure of 10 g / m 2 against a plate heated to 150 ° C. (heat-treated). A near IR absorbing recording sheet was obtained.

The absorptivity of the obtained recording sheet, the background color of the coating surface and the resistance of the IR absorptivity to heat, moisture, and light were determined in the same manner as in Example 3, and the results are summarized in Table 6.

Comparative Example 4

The dispersion A containing the thiourea compound or the dispersion B containing the lead compound used in Example 6 was separately applied in the same manner as in Example 6, dried, and then heat-treated to prepare a product. The near IR absorbance of the product was measured.

For the sheets on which a mixture of the thiourea compound and the lead compound were applied and which had been dried, heat treatment leads to a sheet with a high absorption capacity in the near IR, as can be seen from Table 6. This high IRA absorption capacity is almost not reduced under the influence of heat, moisture and light and it is surprisingly stable against handling and changes in the environmental conditions. The surface of this sheet turns a little gray, but the sheet does not experience any striking changes in color. The sheet to which either the thiourea compound or the lead compound was applied and which had been dried did not have near IR absorption capacity when heat-treated, and therefore the stability of the IR absorption capacity during storage was not tested.<tables id="tabl0011" num="0011"><img file="EP0346772B1_D0039.tif" /></tables><tables id="tabl0012" num="0012"><img file="EP0346772B1_D0040.tif" /></tables>

The mass absorbing mass in the near IR after heat treatment and the sheet containing this mass are almost colorless, and the heated part immediately has a near IR absorption capacity. The heat treatment of the mass or of the sheet containing this heat-treated mass leads to the strong absorption capacity in the very near IR range of 800-2000 nm. Because of the above near IR absorption capacity, the products according to the invention can be used as optical materials such as a thermal detector; Filters for light in the near IR range, recording material; Material to repel or isolate heat rays; Heat collector; Sensor for IR detectors and the like can be used.

The mass or the material obtained through its heat treatment is only slightly discolored despite the presence of metal. Therefore, the shaped bodies (film, sheet, etc.) containing this mass or material have a superior appearance.

The absorptive capacity of the mass absorbing in the near IR after heat treatment, the inventive near IR absorbing material and the shaped body containing this mass or this material is stable to the change in environmental conditions over time, ie it does not deteriorate.

Furthermore, the heat-absorbing mass in the near IR after heat treatment can only be produced by mixing the components, and the material in the near IR absorbing according to the invention can only be produced by heating this mixture. The production of the shaped body containing the material according to the invention does not require a new agent. Therefore, the subject of this invention is suitable for industrial production.