JPH0733427B2 - Method for producing polyurethane resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polyurethane resin, and more specifically, to a siloxane modification excellent in transparency, non-adhesiveness, blocking resistance, flexibility and the like. The purpose is to provide a polyurethane resin.

(Prior Art) Conventionally, polyurethane-based resins have been widely used as binders for various coating agents, paints, inks, etc., films, molded products, etc., and polyurethane-based resins suitable for each application have been proposed.

These polyurethane-based resins are basically obtained by reacting a polyol component, a polyisocyanate component and, if necessary, a chain extender component. Polyurethane resins having various physical properties depending on the type and combination of these components. Resin is provided.

(Problems to be Solved by the Invention) However, regarding the use of the polyurethane resin,
For example, like a heat-resistant layer of a heat-sensitive recording material or a magnetic recording medium,
In some cases, non-adhesion to the thermal head, blocking resistance between films, etc. are required, and in these applications, sufficient flexibility for forming a thin film is usually required at the same time.

As a polyurethane resin that satisfies these requirements,
The present inventors have previously proposed a polyurethane resin containing a siloxane segment.

However, although the polyurethane-based resin is very excellent in non-adhesiveness and blocking resistance, the compatibility between the siloxane segment and other polyol component, polyasocyanate component, chain extender component, etc. is insufficient. In addition, the obtained resin has a milky white color, and in applications where high optical transparency is required, for example, in the fields of various paints, binders for printing inks, molded products, films, etc. There was a problem of shortage.

Therefore, an object of the present invention is to provide a polyurethane-based resin which is excellent in non-adhesiveness, blocking resistance, flexibility and the like and is also excellent in optical transparency.

(Means for Solving Problems) The above object is achieved by the present invention described below. That is, when a polyurethane resin is produced by reacting a polyol component, a polyisocyanate component, and optionally a chain extender component, at least a part of the polyol component is a copolymer of a siloxane compound having active hydrogen and caprolactone. Is a method for producing a polyurethane resin.

(Function) By introducing a copolymer segment of a siloxane compound and caprolactone into a polyurethane resin, a polyurethane resin excellent in non-adhesiveness, blocking resistance, flexibility and the like and optically transparent can be obtained. Provided.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments of the present invention.

The polyurethane resin of the present invention is obtained by reacting a polyol, a polyisocyanate, and optionally a chain extender and the like to obtain a polyurethane resin, which comprises a siloxane compound having active hydrogen and caprolactone as all or part of the polyol. Obtained using a copolymer.

Preferred examples of the active hydrogen-containing siloxane compound used in the present invention include the following compounds.

(1) Amino-modified siloxane oil (M = 1 to 10, n = 2 to 10, R = CH ₃ or OCH ₃ ) (M = 1 to 10, n = 2 to 10, R = CH ₃ or OCH ₃ ) (M = 0 to 200) (N = 2 to 10) (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to
200, m = 2 to 200, n = 2 to 200) (N = 1 to 200, R = lower alkyl group) (2) Epoxy-modified siloxane oil (N = 1 to 200) (M = 1 to 10, n = 2 to 10) (N = 1 to 200) (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to
200, m = 2 to 200, n = 2 to 200) (N = 1 to 10) (M = 1 to 10, n = 2 to 10) The above epoxy compound can be used by reacting it with a polyol, polyamine, polycarboxylic acid or the like so that it has active hydrogen at the terminal.

(3) Alcohol-modified siloxane oil (N = 1 to 200) (M = 1 to 10, n = 2 to 10) (N = 0 to 200) (L = 1 to 10, m = 10 to 200, n = 1 to 5) (N = 1 to 200, R = lower alkyl) (R = lower alkyl group, R ′ = hydrogen atom, alkyl group,
k = 1 to 250, l = 0 to 5, m = 0 to 50, n = 1
Through 3) (R = lower alkyl group, R ′ = hydrogen atom, alkyl group,
k = 1 to 250, l = 0 to 5, m = 0 to 50, n = 1
To 3) (4) Mercapro-modified siloxane oil (M = 1 to 10, n = 2 to 10) (N = 2 to 10) (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to
200, m = 2 to 200, n = 2 to 200) (N = 1 to 200, R = lower alkyl group) (5) Carboxyl-modified siloxane oil (M = 1 to 10, n = 2 to 10) (N = 1 to 200) (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to
200, m = 2 to 200, n = 2 to 200) (N = 1 to 200, R = lower alkyl group) The siloxane compound having active hydrogen as described above is an example of a preferable siloxane compound in the present invention.
The present invention is not limited to these exemplifications, and the above-exemplified compounds and other siloxane compounds are commercially available at present and are easily available from the market, and any of them can be used in the present invention. It is a thing.
Incidentally, in the above siloxane compound, a monofunctional compound can be incorporated into the polyurethane by copolymerizing with caprolactone and then reacting with the polyurethane having NCO at the terminal.

In the present invention, ε-caprolactone that can be reacted with a siloxane compound having active hydrogen is represented by the following general formula.

Most preferred for the purposes of the present invention are ε-caprolactone, monomethyl-ε-caprolactone, monoethyl-ε.
-Various monoalkyl- [epsilon] -caprolactones such as caprolactone, monopropyl- [epsilon] -caprolactone and monododecyl- [epsilon] -caprolactone or two alkyl groups, both without being bound to a carbon atom in the [epsilon] -position. A dialkyl-ε-caprolactone or a carbon atom at the ε-position of the lactone ring which is respectively substituted with a different carbon atom is not di-substituted and thus another 2 or 3 carbon atom is substituted with 3 alkyl. Alkoxy-ε-caprolactones such as trialkyl-ε-caprolactone and ethoxy-ε-caprolactone substituted by groups or cycloalkyl-ε-caprolactones such as cyclohexyl, phenyl- and benzyl-ε-caprolactone,
And aryl-ε-caprolactone and aralkyl-ε-caprolactone.

The reaction between the siloxane compound and the caprolactone is carried out by mixing the two, and preferably using a suitable catalyst under a nitrogen stream, and reacting at a temperature of 150 to 200 ° C. for several hours to several tens of hours to obtain a siloxane-modified polysiloxane. A caprolactone copolymer is obtained. Both can be reacted at any reaction ratio, but for the purpose of the present invention, it is preferable to react them at a ratio of 10 to 80 parts by weight of the siloxane compound per 100 parts by weight of caprolactone. When the amount of the siloxane compound used is too small, the non-adhesiveness, blocking resistance, etc. of the finally obtained polyurethane resin becomes insufficient,
On the other hand, if the amount is too large, the optical transparency of the obtained polyurethane resin is lowered, which is not preferable.

Further, an intermediate obtained by reacting the copolymer as described above with a polyisocyanate as described below so that at least one of the hydroxyl group of the copolymer or the isocyanate group of the polyisocyanate group remains, for example, a bifunctional copolymer It is also possible to use a product obtained by reacting the polymer with a polyfunctional polyisocyanate in a rich isocyanate group or, conversely, an intermediate obtained by reacting the copolymer with a rich reactive group.

Furthermore, a polyester polyol obtained by reacting a copolymer with a polycarboxylic acid can be used in the same manner.

As the polyol that may be used in combination with the siloxane-modified polycaprolactone copolymer, any conventionally known polyol for polyurethane can be used. For example, a terminal group is preferably a hydroxyl group, and a molecular weight of 300 to 300 is preferable.
4,000 polyethylene adipate, polyethylene propylene adipate, polyethylene butylene adipate, polydiethylene adipate, polybutylene adipate, polyethylene succinate, polybutylene succinate, polyethylene sebacate, polybutylene sebacate, polytetramethylene ether glycol, poly-ε-caprolactone Examples include diols, polyhexamethylene adipate, carbonate polyols, polypropylene glycols and the like, and those containing an appropriate amount of polyoxyethylene chains in the above polyols.

As the organic polyisocyanate, any conventionally known one can be used, but preferred examples include 4,4′-diphenylmethane diisocyanate (MDI), hydrogenated MDI, isophorone diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc., or organic polyisocyanates thereof As a matter of course, a urethane prepolymer obtained by reacting a low molecular weight polyol or polyamine with a terminal isocyanate to obtain a urethane prepolymer can be used.

As the chain extender, any conventionally known one can be used, but preferred examples thereof include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, ethylenediamine, 1, 2-propylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, isophoronediamine, m-xylylenediamine, hydrazine, water and the like.

Among the polyurethane-based resins obtained from the materials as described above, particularly preferable one is that the siloxane-caprolactone copolymer segment is about 10 in the polyurethane-based resin molecule.
If the copolymer is less than about 10% by weight, the non-adhesiveness, which is the intended purpose of the present invention, the expression of blocking resistance, etc. becomes insufficient, while the amount of 80% by weight is 80% by weight. If it exceeds, transparency and flexibility of the resulting polyurethane resin will be insufficient, which is not preferable.

The preferred ones have a molecular weight of 20,000 to 500,000, and the most preferred ones have a molecular weight of 20,000 to 250,000.

Further, in the present invention, the above copolymer and polyisocyanate are reacted in an isocyanate-rich state to obtain a polyurethane resin having at least one free isocyanate group, which is used in combination with another film-forming resin. Then, it can be used as a modifier thereof.

The polyurethane resin of the present invention containing the siloxane caprolactone copolymer segment as described above can be easily obtained by a conventionally known production method. These polyurethane-based resins may be prepared without solvent,
Although it may be prepared in an organic solvent, it is advantageous in that the solution obtained by preparing it in an organic solvent can be used as it is for various purposes.

Preferred as such an organic solvent are methyl ethyl ketone, methyl-n-propyl ketone, methyl isobutyl ketone, diethyl ketone, methyl formate, ethyl formate,
Propyl formate, methyl acetate, ethyl acetate, butyl acetate and the like, and also acetone, cyclohexane, tetrahydrofuran, dioxane, methanol, ethanol, isopropyl alcohol, butanol, toluene, xylene,
Dimethylformamide, dimethylsulfoxide, perchlorethylene, trichloroethylene, methylcellosolve, butylcellosolve, cellosolve acetate and the like can also be used.

The polyurethane resin obtained by the present invention as described above has excellent non-adhesiveness and blocking resistance, but is easily soluble in various organic solvents and forms an excellent transparent and flexible film. You can do it.

Therefore, a binder for forming a magnetic layer of a magnetic recording medium such as a magnetic tape, a back coat formed on the back surface thereof,
Binders such as transfer film, formation of heat resistant layer for preventing adhesion of thermal head, formation of release layer such as synthetic leather material, fiber coating agent, surface treatment agent, release paper,
Very useful as a binder for paints and printing inks.

Next, one example of the use of the polyurethane resin obtained in the present invention
The formation of a heat-resistant layer of a heat-sensitive recording material such as a heat transfer film will be described as a seed.

A heat-sensitive recording material is a substrate film such as a polyester film provided with a transfer ink layer or a sublimation transfer dye layer on one surface, and an image layer is heated by a thermal head from the back side to transfer the ink layer or dye to the transfer material. Then, a mono-color or multi-color image is formed, and during transfer by the thermal head, the thermal head adheres to the back surface and causes various troubles.

The polyurethane-based resin obtained in the present invention has excellent flexibility and excellent non-adhesiveness especially at elevated temperature, and thus is most suitable for such purpose. Of course, this example is merely one example, and the application of the polyurethane resin of the present invention is not limited to the above example.

For the formation of the heat-resistant layer, it is preferable to use a coating material formed by dissolving or dispersing the above-mentioned polyurethane resin of the present invention alone or a mixture with another resin in the medium as described above. The concentration of the total film forming resin in the paint is preferably about 10 to 55% by weight, and the polyurethane resin of the present invention can be used in a ratio of about 1 to 100 parts by weight per 100 parts by weight of these film forming resins. .

As the film-forming resin, various conventionally known film-forming resins can be used in combination, and any of these can be used, for example, vinyl chloride resin, vinylidene chloride resin, vinyl chloride / vinyl acetate / vinyl alcohol. Copolymer resin, alkyd resin, epoxy resin, acrylonitrile-butadiene resin, polyurethane resin, polyurea resin, nitrocellulose resin, polybutyral resin, polyester resin, fluorine resin, melamine resin, urea Resins, acrylic resins, polyamide resins, etc., and particularly when the polyurethane resin of the present invention has a free isocyanate group, a resin having a reactive group capable of reacting with an isocyanate group in its structure. Is preferably used. Any of these resins may be used alone or as a mixture, and may be a solution or dispersion in an organic solvent.

The heat-resistant layer-forming coating material, as long as the above-mentioned components are essential components, other subcomponents other than the above, for example, pigments, extender pigments, plasticizers, antistatic agents, surfactants, lubricants, crosslinking agents,
It may contain any additives such as an anti-aging agent, a stabilizer, a foaming agent and an antifoaming agent.

The method itself for forming the heat-resistant layer may be the same as a conventionally known method, and it is preferable to form the heat-resistant layer to a thickness of about 0.1 to 10 μm.

As the substrate sheet to be used, any conventionally known one can be used, for example, a polyester film, a polypropylene film, a cellulose triacetate film, a cellulose diacetate film, a polycarbonate film or the like having a thickness of 5 to 50 μm is arbitrarily used. You can

The heat-sensitive recording material may be any known method except that the polyurethane-based resin as described above is used for forming the heat-resistant layer,
For example, the heat-sensitive recording layer can be formed from a conventionally known binder resin, a dye or pigment, an organic solvent and various necessary additives according to a conventionally known method.

For example, as the binder resin, a resin such as the above film-forming resin can be used, an organic solvent such as the above can also be used as an organic solvent, an additive such as the above can be used as an additive, and a dye or a pigment may be, for example, , Azo-based, phthalocyanine-based, quinacridone-based, organic pigments such as polycyclic pigments, carbon black, iron oxide, yellow lead, inorganic pigments such as cadmium sulfide can be used, and as the dye, various conventionally known dyes and Sublimable dyes and disperse dyes can be used.

(Effect) The polyurethane-based resin of the present invention obtained as described above has excellent solvent solubility, gives an excellent transparency and a flexible film, and has excellent high-temperature non-adhesiveness,
Since it has blocking resistance and the like, it is useful for various applications as described above.

(Examples) Next, the present invention will be described more specifically with reference to Examples, Comparative Examples, and Usage Examples. In the text, parts and% are based on weight.

Example 1 (K is a value at which the molecular weight becomes 980.) 310 parts of ε-caprolactone and the above structure (1) are contained in a reactor equipped with a stirrer, a thermometer, a nitrogen gas introducing pipe, and a reflux condenser. Alcohol-modified siloxane oil 15
0 parts and 0.05 parts of tetrabutyl titanate were charged and reacted at 180 ° C. for 10 hours under a nitrogen stream to obtain a polysiloxane-polyester copolymer having a hydroxyl value of 37, an acid value of 0.40 and a molecular weight of 3,030.

20 parts of 150 parts of the above copolymer and 27 parts of 1,4-butanediol are added.
It is dissolved in a mixed solvent of 0 part of methyl ethyl ketone and 100 parts of dimethylformamide, and stirred at 60 ° C. with good stirring.
One part of hydrogenated MDI dissolved in 188 parts of dimethylformamide was gradually added dropwise, and after completion of the addition, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of the present invention. This solution is very transparent with 35% solids at 35,500 cps (25 ° C)
It had a viscosity of.

Example 2 75 parts of the copolymer of Example 1, 75 parts of polybutylene adipate (hydroxyl value 56.0, acid value 0.40, molecular weight 2,000) and 27 parts of 1,4-butanediol were mixed with 200 parts of methyl ethyl ketone and 150 parts.
Part of dimethylformamide dissolved in a mixed solvent, 60
A mixture of 90 parts of MDI dissolved in 146 parts of dimethylformamide was slowly added dropwise while stirring well at ℃.
The reaction was carried out at 6 ° C for 6 hours to obtain the polyurethane resin solution of the present invention. This solution is very transparent and has a solids content of 35%.
It had a viscosity of 1,200 cps (25 ° C).

Comparative Example 1 150 parts of the siloxane oil of structural formula (1) from Example 1 and
27 parts of 1,4-butanediol was dissolved in a mixed solvent of 250 parts of methyl ethyl ketone and 100 parts of dimethylformamide, and 118 parts of hydrogenated MDI was added to 198 while stirring well at 60 ° C.
What was dissolved in a part of dimethylformamide was gradually added dropwise, and after completion of the addition, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of a comparative example. The solution was milky white, had a solids content of 35% and a viscosity of 18,600 cps (25 ° C.).

Comparative Example 2 49 parts of the siloxane oil of the above structural formula (1) having the same siloxane / polyester ratio as the copolymer of Example and poly ε-caprolactone (hydroxyl value 56.0, acid value 0.28, molecular weight
2,000) 101 parts and 1,4-butanediol 27
Parts were dissolved in a mixed solvent of 250 parts of methyl ethyl ketone and 100 parts of dimethylformamide, and 105 parts of hydrogenated MDI dissolved in 174 parts of dimethylformamide were gradually added dropwise with good stirring at 60 ° C. After completion of the dropping, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of a comparative example.
The solution was opalescent, had a solids content of 35% and a viscosity of 26,200 cps (25 ° C.).

Example 3 (K is a value at which the molecular weight becomes 1,900.) A reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a reflux condenser has 166 parts of ε-caprolactone and the above structure (2). Alcohol-modified siloxane oil 15
Charge 0 parts and 0.04 parts of tetrabutyl titanate, react for 10 hours at a temperature of 180 ° C under a nitrogen stream, and have a hydroxyl value of 28,
A polysiloxane-polyester copolymer having an acid value of 0.35 and a molecular weight of 4,010 was obtained.

20 parts of 150 parts of the above copolymer and 27 parts of 1,4-butanediol are added.
Dissolve it in a mixed solvent of 0 parts of methyl ethyl ketone and 100 parts of dimethylformamide and stir well at 60 ° C. 88
One part of hydrogenated MDI dissolved in 192 parts of dimethylformamide was gradually added dropwise, and after completion of the reaction, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of the present invention. This solution is highly transparent and has 35% solids and 31,200 cps (25 ° C)
It had a viscosity of.

Example 4 75 parts of the copolymer of Example 3, 75 parts of polyethylene adipate (hydroxyl value 56.0, acid value 0.28, molecular weight 2,000) and 27 parts of 1,4-butanediol were added to 200 parts of methyl ethyl ketone and 150 parts of dimethylformamide. Dissolved in a mixed solvent of 60 ℃
A solution of 93 parts of MDI dissolved in 151 parts of dimethylformamide was slowly added dropwise with thorough stirring at 80 ° C after the addition was completed.
And reacted for 6 hours to obtain the polyurethane resin solution of the present invention. This solution is very transparent and has a solid content of 35% at 40,5
It had a viscosity of 00 cps (25 ° C).

Comparative Example 3 150 parts of the siloxane oil of structural formula (2) from Example 1 and
27 parts of 1,4-butanediol is dissolved in a mixed solvent of 250 parts of methyl ethyl ketone and 100 parts of dimethylformamide, and 99 parts of hydrogenated MDI is dissolved in 162 parts of dimethylformamide while stirring well at 60 ° C. The dissolved product was gradually added dropwise, and after completion of the addition, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of a comparative example. The solution was milky white and had a viscosity of 18,200 cps (25 ° C) at 35% solids.

Comparative Example 4 71 parts of siloxane oil of the above structural formula (2) having the same siloxane / polyester ratio as the copolymer of Example 2 and 78 parts of poly ε-caprolactone (hydroxyl value 56.0, acid value 0.28, molecular weight 2,000) And 1,4-butanediol 27
Parts were dissolved in a mixed solvent of 200 parts of methyl ethyl ketone and 150 parts of dimethylformamide, and 98 parts of hydrogenated MDI dissolved in 161 parts of dimethylformamide were slowly added dropwise while stirring well at 60 ° C. After completion of the dropping, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of a comparative example. The solution was milky white, had a solids content of 35% and a viscosity of 38,100 cps (25 ° C.).

Example 5 (M is a value at which the molecular weight becomes 1,600.) A reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a reflux condenser has 178 parts of ε-caprolactone and the above structure (3). Amino-modified siloxane oil (150 parts) and tetrabutyl titanate (0.04 parts) were inserted and reacted under a nitrogen stream at a temperature of 180 ° C for 10 hours to give a hydroxyl value of 32 and an acid value of 32.
A polysiloxane-polyester copolymer having a molecular weight of 0.28 and a molecular weight of 3,500 was obtained.

20 parts of 150 parts of the above copolymer and 27 parts of 1,4-butanediol are added.
It is dissolved in a mixed solvent of 0 part of methyl ethyl ketone and 100 parts of dimethylformamide, and stirred at 60 ° C. with good stirring.
One part of MDI dissolved in 187 parts of dimethylformamide was gradually added dropwise, and after completion of the addition, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of the present invention. This solution was very transparent and had a viscosity of 35,600 cps (25 ° C) at 35% solids.

Comparative Example 5 150 parts of the siloxane oil of structural formula (3) from Example 5 and
27 parts of 1,4-butanediol dissolved in a mixed solvent of 200 parts of methyl ethyl ketone and 150 parts of dimethylformamide, 98 parts of MDI dissolved in 161 parts of dimethylformamide with good stirring at 60 ° C. Was gradually added dropwise, and after completion of the addition, reaction was carried out at 80 ° C. for 6 hours to obtain a polyurethane resin solution of a comparative example. The solution is milky white and has a solid content of 35%.
It had a viscosity of 28,600 cps (25 ° C).

Comparative Example 6 69 parts of the siloxane oil of the structural formula (3) having the same siloxane / polyester ratio as the copolymer of Example 3 and 81 parts of polybutylene adipate (hydroxyl value 56.0, acid value 0.40, molecular weight 2,000). Mixture, and 1,4-butanediol 27
Part was dissolved in a mixed solvent of 200 parts of methyl ethyl ketone and 150 parts of dimethylformamide, and 95 parts of MDI dissolved in 155 parts of dimethylformamide were gradually added dropwise while stirring well at 60 ° C, and the addition was completed. Then, the mixture was reacted at 80 ° C. for 6 hours to obtain a polyurethane resin solution of Comparative Example. The solution was milky white, had a solids content of 35% and a viscosity of 41,2000 cps (25 ° C.).

The results obtained by measuring the breaking strength, the breaking elongation, and the light transmittance (cloudiness value) of the films obtained from the above respective solutions based on JIS K7311 are shown in Table 1.

Use Examples 1 to 5 and Comparative Use Examples 1 to 3 A coating material containing the following components was prepared, and a dry thickness of 0.5 was formed on the back surface of a 15 μm-thick polyester film having a thermosensitive recording layer formed in advance. The coating was applied by a gravure coater to a thickness of μm, and the solvent was dried in a dryer to form a heat-resistant layer. This was cut into a predetermined width to prepare a heat-sensitive recording material using the polyurethane resin of the present invention and a heat-sensitive recording material for comparison.

Use Example 1 100 parts of resin solution of Example 1 100 parts of methyl ethyl ketone Use example 2 100 parts of resin solution of Example 2 100 parts of methyl ethyl ketone Use example 3 100 parts of resin solution of Example 3 100 parts of methyl ethyl ketone Use example 4 Resin of Example 4 Solution 100 parts Methyl ethyl ketone 100 parts Use example 5 Resin solution of Example 5 100 parts Methyl ethyl ketone 100 parts Comparative use example 1 Resin solution of reference example 1 100 parts Methyl ethyl ketone 100 parts Comparative use example 2 Resin solution of reference example 1 100 parts Talc 5 parts Methyl ethyl ketone 120 parts Comparative use example 3 Resin solution of reference example 2 100 parts Reference example 1 Polybutylene adipate (molecular weight 2,000) 150 parts and 1,4
-Butanediol 5 parts with 5 parts 200 parts methyl ethyl ketone
A solution prepared by dissolving 62 parts of water-added MDI in 171 parts of dimethylformamide was slowly added dropwise to 0 part of dimethylformamide while stirring well at 60 ° C, and after completion of the reaction, the reaction was carried out at 80 ° C for 6 hours.

The solution had a solids content of 35% and a viscosity of 32,000 cps (25 ° C.). The film obtained from this solution has a breaking strength (kg / cm ² ) of 450, a breaking elongation (%) of 480, and a softening point of
It was 110 ° C.

For the softening point above, cut the film into strips,
Attach a cone to the lower end of the film so that the weight becomes 450 g / cm ² , hang it in a gear oven, and then raise the temperature at a rate of 2 ° C / min. To rapidly increase the film elongation or cut the film. It is obtained as the temperature.

Reference Example 2 100 parts of a silicone resin (KS-841) manufactured by Shin-Etsu Chemical Co., Ltd. and 1 part of a catalyst (PL-7) were dissolved in 1,000 parts of toluene,
It was used as a coating liquid of silicone resin.

Evaluation The characteristics of the heat-sensitive recording materials obtained in Use Examples 1 to 5 and Comparative Use Examples 1 to 3 are shown in Table 1 below.

The friction coefficient in Table 2 above is a measured value of the friction coefficient between the untreated surface of polyethylene terephthalate and the heat-resistant layer formed in the present invention or the comparative use example.

The sticking property was subjected to a thermal recording mounting test, and the detachability of the thermal recording material from the thermal head at the time of pressing operation between the thermal head and the thermal recording material was visually evaluated in 5 stages, and the best one was selected. It was set to 5.

As for the dirt on the head, it was subjected to a mounting test for thermal recording, and the dirt condition of the thermal head was observed.
Was evaluated in 5 levels.

From the above results, it is clear that the heat-sensitive recording material using the polyurethane resin of the present invention has a low coefficient of friction of the heat-resistant layer, low tackiness and little head contamination.

Claims (3)

[Claims] 1. When a polyurethane resin is produced by reacting a polyol component, a polyisocyanate component and optionally a chain extender component, a siloxane compound having at least a part of an active hydrogen group and a caprolactone are prepared. A method for producing a polyurethane resin, which is a copolymer. 2. The method for producing a polyurethane resin according to claim 1, wherein the copolymer is obtained by reacting a siloxane compound in an amount of 10 to 80 parts by weight per 100 parts by weight of caprolactone. 3. The proportion of the copolymer segment in the polyurethane resin is 10 to 80% by weight.
The method for producing a polyurethane resin according to claim 1, which is used in an amount that