JPH02131984A - Reversible heat sensitive recording material - Google Patents

Abstract

PURPOSE:To improve adhesive properties with heating means when an image is formed by heating, to improve heating sensitivity and to obtain a fresh image by providing a stick preventive layer selected from graft polymer with silicone resin, etc., as a branch polymer. CONSTITUTION:A support made of plastic film, a glass plate, a metal plate, etc., is coated with dispersant in which organic low polymer substance is dispersed in fine particle state in solution dissolved with resin base material and organic low molecular weight substance or solution of resin base material, and dried to form a heat sensitive layer. The ratio of the organic low polymer substance and resin base material in the layer is desirably 1:0.5-1:16 by weight. Then, it is coated with solution dissolved or dispersed with graft polymer with fluorine mold release agent or silicone resin as branch polymer, and dried to form a stick preventive layer. Thus, adhesive properties with a thermal head, etc., are improved, thermal sensitivity is improved as compared with that of a conventional one, and a fresh image can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a reversible thermosensitive recording material that performs recording and erasing by utilizing a reversible change in transparency of a thermosensitive member depending on temperature.

[Prior art]

As a thermosensitive recording material that can be reversibly recorded and erased,
It is known that a heat-sensitive layer is provided on a support by dispersing an organic low-molecular substance such as a higher alcohol or a higher fatty acid in a resin such as polyester or polyamide (Japanese Unexamined Patent Application Publication No. 1983-1982).
119377, Japanese Patent Application Laid-Open No. 55-154198, etc.). Recording, that is, image formation and erasing using such recording materials utilizes the change in transparency of the heat-sensitive layer depending on the temperature.

However, in conventional reversible thermosensitive recording materials, when forming an image by heating the surface with a thermal head, etc., the friction with these heating means is large, so sufficient adhesion cannot be achieved, resulting in a decrease in thermal sensitivity. As a result of unevenness on the surface,
It was difficult to form clear images. Furthermore, in severe cases, a phenomenon in which the thermal head stopped running was observed.

In order to avoid such inconveniences, the applicant of the present application first formed (i) an overcoat layer mainly composed of silicone rubber or silicone resin on the heat-sensitive layer (Japanese Patent Application No. 62-55650). ) or (ii) Polysiloxane Graph 1 to form an overcoat layer mainly composed of polymer (Japanese Patent Application No. 152550/1982), thereby proposing a reversible thermosensitive recording material with reduced surface friction. However, in the case of (i), the adhesion between the heat-sensitive layer and the overcoat layer is still not sufficient, and repeated mechanical stimulation causes the overcoat layer to peel off, causing image deterioration. I have a problem. On the other hand, in the reversible heat-sensitive recording material (i), the adhesion between the heat-sensitive layer and the overcoat layer is considerably improved compared to that in (i), and when images are repeatedly formed and erased on the same part, This rarely causes any particular problems, but if you print another part continuously using a thermal head, etc., part of the overcoat layer will peel off, and this will adhere to the thermal head, etc., eventually making it difficult to form an image. It has such defects.

and. What these (i) and (it) have in common is that the main chain of the overcoat layer has a siloxane bond, which greatly affects the adhesiveness with the recording layer. It is inferred that.

〔the purpose〕

The present invention provides a reversible thermosensitive recording material that can form clear images by improving thermal sensitivity and improving the adhesion with heating means when forming images by heating with a thermal head or the like. .

〔composition〕

The reversible heat-sensitive recording material of the present invention has a resin base material and a heat-sensitive layer whose transparency changes reversibly depending on temperature, which is mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material, on a support. A stick prevention layer is further provided thereon, the main component being at least one selected from a fluorine-based mold release agent and a graft polymer having a silicone-based resin as a branch polymer. .

Incidentally, the inventors of the present invention have conducted various studies to eliminate the above-mentioned inconveniences and defects, and as a result, we have developed an overcoat layer made of silicone resin that has both heat resistance and slipperiness against heating means such as thermal heads. It has been confirmed that a high-quality reversible thermosensitive recording material capable of performing desired recording over a long period of time can be obtained by forming the material on the thermosensitive layer using a graft polymer or a fluorine-based mold release agent as the main component. The reason why such a favorable effect is observed is considered to be due to the fact that the overcoat layer is formed of a resin or the like that does not contain a siloxane bond in the main chain. The present invention has been made based on this.

The invention will be explained in more detail below with reference to the accompanying drawings.

The recording principle of the recording material of the present invention utilizes the change in transparency due to temperature of the heat-sensitive layer, and is well known in itself, but will be described again as we proceed with the explanation of the present invention. Since this seems more convenient, I will explain this recording principle using a drawing (Figure 1).

In the drawing, for example, the heat-sensitive layer is in a cloudy, opaque state at room temperature below 2. If it is heated to a temperature between T and F2, it becomes transparent, and even if it is returned to room temperature below T6 in this state, it remains transparent. It remains as it is.

Further heating to a temperature of T or higher results in a translucent state intermediate between maximum transparency and maximum opacity.

Next, when this temperature is lowered, the liquid returns to its initial cloudy and opaque state without becoming transparent again.

Note that if this opaque state is heated to a temperature between T0 and Te and then cooled to room temperature, that is, a temperature below T0, it can assume a state between transparent and opaque. Also, if the material that becomes transparent at room temperature is heated again to a temperature above T and returned to room temperature, it will return to its cloudy, opaque state.

That is, it can take both opaque and transparent forms, as well as an intermediate state between them, at room temperature.

Therefore, for example, after heating the entire layered heat-sensitive member having a heat-sensitive layer with such properties (a support with heat-sensitive stores or a heat-sensitive sheet) to a temperature between T and T2, it is heated to a room temperature below T. If it is cooled to become transparent and then partially heated to a temperature of T or higher using a thermal head or the like to make that part opaque, a white image is formed. And this? If a layered colored member is placed on the back side of a layered heat-sensitive member having a color image, this image can be recognized as a white image against the background of the color of the colored member.

On the other hand, after heating the entire layered heat-sensitive member to a temperature above T, and returning it to room temperature below To to make it cloudy and opaque, partially heat it with a thermal head etc. to a temperature between T■ and T2 to remove that part. When made transparent, a transparent image is formed on the white surface. If a colored member is placed on the back side of a layered heat-sensitive member having such a transparent image, this image can be recognized as an image of the color of the colored member against a white background.

Recording and erasing on the layered heat-sensitive member as described above can be repeated at least 104 times.

If the image obtained in this way is projected onto a screen using an overhead projector (○HP), for example,
The transparent part transmits light, but the cloudy part scatters light and is opaque, so a positive or negative projected image can be formed on the screen. In other words, by using a reversible layered heat-sensitive member, it is possible to
You can easily create OHP sheets without creating P sheets or OHP sheets using a word processor or thermal transfer ribbon.
P sheets can be created.

By the way, as mentioned earlier, when the heat-sensitive layer (reversible heat-sensitive recording layer) comes into direct contact with the thermal head and is heated, the heat-sensitive layer melts and sticks to the thermal head, and in severe cases, the running of the thermal head is interrupted. This can cause defects, and sometimes even cause the thermal henode to stop running. Therefore, an overcoat layer is generally formed on the heat-sensitive layer to prevent such problems. As mentioned above, various defects have been found in the conventional overcoat layers 1 to 1.

In the recording material of the present invention, this overcoat layer is formed as a stick prevention layer containing a specific mold release agent as a main component that has both heat resistance and slipperiness against a thermal head. The thus obtained reversible thermosensitive recording material can have a significantly reduced coefficient of friction on its surface.

By the way, when an image is formed by heating with a line head among thermal heads, the recording material is sandwiched between the head and the platen roller, is pressed by the head and moves in accordance with the movement of the platen roller, and is relatively As the position relative to the head moves, each line is selectively heated and an image is formed. At this time, the reversible thermosensitive recording material of the present invention has a very small surface friction coefficient as described above. , it is very smooth when moving while being suppressed by the head, so it is less likely to melt and adhere to the head.
That is, the adhesion with the head is good, and as a result, the transfer of heat from the thermal head to the recording material, that is, the thermal sensitivity is good, and in addition, the stick prevention layer does not peel off due to movement of the head.

In order to produce the reversible thermosensitive recording material of the present invention, a method is generally employed in which a thermosensitive layer (reversible thermosensitive recording layer) is formed on a support by the following method, and then a stick prevention layer is formed. , (l), the heat-sensitive layer material may be formed into a self-supporting heat-sensitive sheet by a normal film-forming method without using any particular support.

(1) An organic low-molecular substance is dispersed in the form of fine particles in a solution in which a resin base material and an organic low-molecular substance are dissolved, or in a solution of the resin base material (use a solvent that does not dissolve the organic low-molecular substance). A heat-sensitive layer is formed by coating and drying the dispersion on a support such as a plastic film, glass plate, or metal plate. Next, (2) A solution in which a fluorine-based mold release agent (a fluorine-based resin, a graft polymer having a fluorine-based resin as a branch polymer) or a graft polymer having a silicone-based resin as a branch polymer is dissolved or dispersed is applied thereon and dried. to form an anti-stick layer.

As the solvent for forming the heat-sensitive layer, various solvents can be used depending on the type of organic low-molecular substance and resin base material. For example, tetrahydrofuran, methyl ethyl ketone,
Methyl isobutyl ketone, chloroform, carbon tetrachloride,
Organic solvents such as ethanol, toluene, 5-xylene, and benzene can be used.

In the heat-sensitive layer thus formed, the organic low-molecular substance exists in a dispersed state as fine particles in the resin base material.

The resin base material used in the heat-sensitive layer forms a film or sheet in which a low-molecular-weight organic substance is uniformly dispersed, and is a material that influences the transparency at maximum transparency. For this reason, the resin material is preferably a resin that has good transparency, is mechanically stable, and has good film-forming properties. Such resins include polyvinyl chloride: vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer. Vinyl chloride copolymers such as polymers; vinylidene chloride-vinyl chloride copolymers, vinylidene chloride-acrylonitrile copolymers, etc.; polyesters; polyamides; polyacrylates or polymethacrylates or acrylate-methacrylate copolymers Coalescence: Examples include silicone resin. These may be used alone or in combination of two or more.

On the other hand, the organic low-molecular substance may be appropriately selected depending on the temperature range T11 to T shown in FIG.
~200°C, particularly preferably about 50 to 150"C. Examples of such organic low-molecular substances include anolecanol; alkanedionol; halogen alkanol or halogen alkanediol; alkylamine=anolecane; anolekene; alkyne; halogen Alkanes; halogen alkenes, halogen anolequins; cycloalkanes;
Cycloalkene: Cycloalkyne; Saturated or unsaturated mono- or dicarboxylic acids or their esters, amides or ammonium salts; Saturated or unsaturated halogenated fatty acids or their esters, amides or ammonium salts; Allylcarboxylic acids or their esters, amides or ammonium salts; halogen allylcarboxylic acids or their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids or their esters,
Examples include amine or ammonium salts; carboxylic acid esters of thioalcohols, and the like. These may be used alone or in combination of two or more. The number of carbon atoms in these compounds is 1
0-6o, preferably 10-38, particularly preferably 10
~3o. The alcohol group moiety in the ester may be saturated or unsaturated, and may be substituted with halogen. In any case, the organic low-molecular substance contains at least one of oxygen, nitrogen, sulfur, and halogen in the molecule, such as -OH, -C○OH, -CONH,...
-GOOR(R is -CnH2..;
n=1-20), -NH-, -NH2, -S--
Preferably, it is a compound containing SS-, -O-, halogen, etc.

More specifically, these compounds include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid,
Stearic acid, behenic acid, nonadecanoic acid, arachidic acid,
High in oleic acid, etc.? Fatty acids; esters of higher fatty acids such as methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, dodecyl behenate; CiGI+, -0-C, . H. 3, C,,H■3
-S-CIGH)3 TCHH)7-S-C151
'l3v,Ce2}12K-S-C12HZS IC
1.3H3g-S-Cz9H3g-Ce2H2,~S
-S-Ci 2 1{2 S ,? 1{2・CH,・O
COC. 21{■,? Il■・CI+2・coco2
Allo? ? H2・C■2・Coo (CHz)t
s・CIl・CH2・CH■SteCH2・CH2・Coo (CI12), s・CIl
・C}12・(Jl, C11, etc.) There are ethers or thioethers.

The weight ratio of the organic low-molecular substance to the resin base material in the heat-sensitive layer is preferably about 1:0.5 to 1:16. If the ratio of the resin base material is below this, it will be difficult to form a film that retains the organic low molecular weight substance in the resin base material.
If it exceeds this level, the amount of organic low molecular weight substances will be small, so
It becomes difficult to make it opaque.

The forming liquid for the stick prevention layer is prepared by dissolving the mold release agent component (fluorine resin, graft polymer having a fluorine resin as a branch polymer) or graft polymer having a silicone resin as a branch polymer in a poor solvent that does not damage the heat sensitive layer. Prepared by uniform dispersion. Examples of the poor solvent here include alcohols (methanol, ethanol, butanol, impropanol, etc.), nonpolar solvents (n-hexane, cyclohexane, etc.), chlorofluorocarbon solvents, water, and the like. Incidentally, when the anti-stick layer forming liquid is prepared by emulsifying the release agent component and uniformly dispersing it in water, it is preferable to add a surfactant. This is because the anti-stick layer forming liquid simply made of water as a dispersion is difficult to uniformly coat due to the organic low molecular compound in the heat-sensitive layer, and is therefore effective in improving wettability. When the above-mentioned graft polymer is used as a mold release agent component, it is also effective to use auxiliary additive components such as metal oxide particles and silicone oil.

Typical examples of fluorine-based resins include polytetrafluoroethylene,
Examples include polytrifluorochloroethylene, polyvinylidene fluoride, and copolymers of tetrafluoroethylene and hexafluoropropylene. These are commercially available under various trade names from Daikin Industries, Ltd., Mitsui Fluorochemical Co., Ltd., Asahi Glass Co., Ltd., and others.

On the other hand, graft polymers in which a fluororesin or silicone resin is used as a branch polymer include a fluororesin or silicone resin that has a polymerizable functional group at one end of the molecular chain as a branch polymer, and various monomers as a backbone polymer. It is synthesized by copolymerization. Various fluorine-based resin skeletons or silicone resin skeletons can be used to constitute the branch polymer, but especially +C
Fluororesins having polytetrafluoroethylene units represented by F, + and (S i+ C H 3 + −
A silicone resin having a polydimethylsiloxane unit represented by 0) is preferably used.

In addition, the polymerizable functional group bonded to one end of such a fluororesin skeleton or silicone resin skeleton is (meta)
There are vinyl polymerization types containing acryloyloxy, allyloxy, glycidyl methacrylate, etc., and polycondensation types containing dihydroxy, dicarboxy, etc. Such branched polymers can be synthesized by various methods. For example, K. Ito. N. Usami. Y+'/am
ashita: Macromolecules. 13
．． 261 (1930) Y, Yamashita.
Y, Chujo. II, Kobayashi. Y
, κawakami: polym. Bu11. ，
5.361 (1!381) etc. is proposed.

Among these, preferred is a method in which a prepolymer of terminal carboxylic acid, alcohol, etc. is synthesized by radical polymerization using a chain transfer agent, etc., and a double bond is introduced by terminal group conversion.

Furthermore, a dicarboxylic acid or diol can be introduced at one end using a chain transfer agent having a dicarboxyl group or a dihydroxy group.

Preferred among these are those obtained by reacting a living polymer obtained by anionically polymerizing a cyclic siloxane represented by the following general formula (a) with a radically polymerizable silicone compound represented by the following general formula (b). method (Japanese Unexamined Patent Publication No. 511-126473). R1 (However, R1 is a methyl group, ethyl group, or phenyl group, and p is 3 or 4.) or CH2=Ct++
Si(R')rr+CQ. (However, R2 is hydrogen or a methyl group; R3 and R4 are methyl, ethyl, or phenyl groups; m is O or 1; n is an integer from 1 to 3; Q is m=
In the case of o, it is an integer of O to 2, and in the case of m=1, it is 2. ) The anionic polymerization of the cyclic siloxane may be carried out according to a conventional method, and can be easily carried out by a bulk polymerization method or a solution polymerization method using a known anionic polymerization initiator.

Examples of the cyclic siloxane represented by general formula (a) are:
Examples include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, hexaethylcyclotrisiloxane, octaethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, and octaphenylcyclotetrasiloxane. Cyclotrisiloxane and octamethylcyclotetrasiloxane are particularly preferred in terms of low cost and ease of anionic polymerization.

Examples of anionic polymerization initiators include known ones such as organolithium compounds, alkali metal hydroxides, alkali metal alkoxides, and alkali metal silanolates.
Among these, organic lithium compounds are particularly preferred. The molecular weight of the living polymer obtained by anionic polymerization controls the molecular weight of the radically polymerizable silicone-based heptanomer, and is controlled by the molar ratio of cyclic siloxane to initiator, with the molar ratio of initiator/cyclic siloxane being o
．． oi to 0.2 is preferred. If it is less than 0.01, the radically polymerizable silicone monomer will have an extremely high molecular weight (more than 20,000), and if it exceeds 0.2, the silicone macromonomer will tend to have an extremely low molecular weight. Average molecular weight is 1000-2
0,000, but if the molecular weight is less than 1,000, the effect of the silicone, ie, low friction properties, will be reduced, and the elegance will also be slightly reduced, and if it exceeds 20,000, the resulting coating resin will tend to be oily.

The radically polymerizable silicone branch monomer can be obtained as in Doki, or by reacting the ping polymer with the radically polymerizable silicone compound represented by the general formula (b) (living polymerization termination reaction). . This reaction is easily carried out by mixing the two.
The radically polymerizable silicone compound represented by the general formula (b) can be easily obtained by a known method. For example, R2 υ (R". R3. Q and n are the same as above), R2 (R2, Q and m are the same as above) and unsaturated acrylate and/or methacrylate (hereinafter collectively referred to as "(meth)acrylate") and HSi(R
'). ．． It can be obtained by a hydrosilylation reaction with -nCQn (R', n are the same as above). The amount of the radically polymerizable silicone compound used is SL-CQ. The amount is preferably 1 to 5 times equivalent.

Another preferred example is radical polymerization by condensation reaction of silicone represented by the following general formula (a') and 0.25-1 mol of an acrylic compound represented by the following general formula (b') per 1 mol thereof. This is a method for obtaining a synthetic silicone monomer (Japanese Patent Application Laid-open No. 154766/1983).

R5 (a)' H O (Sio) nH R' (R % and R6 are a monovalent aliphatic hydrocarbon group with 1 to 10 carbon atoms, a phenyl group, or a monovalent halogenated hydrocarbon group. n is 1 or more ) (R7 is a hydrogen atom,
or a methyl group; Ra is a methyl group; an ethyl group or a phenyl group; X is a chlorine atom, a methoxy group or an ethoxy group.

) The details of this manufacturing method are as described in the above-mentioned patent publication, and various types of silicone represented by the general formula (a') are easily available, and from among them, You can use the one that suits R'.
Particularly preferred are silicones in which R' is a methyl group. General formula (
n in a') is a factor that determines the molecular weight of silicone, and this n is preferably 1 to 500, more preferably 10 to 300. When n is less than 1, the effects of silicone, ie, low friction and patternability, cannot be obtained, and when n exceeds 500, the obtained silicone-based graft copolymer becomes oily and difficult to purify.

Examples of the acrylic compound represented by the general formula (b') include γ-methacryloxypylphenylmethyldichlorosilane, γ-methacrylicoxypylphenylmethyldiethoxysilane, γ-methacrylicoxypylphenyldichlorosilane, Examples include γ-methacrylicoxymethylethyldichlorosilane and γ-acrylicoxymethyldichlorosilane. These acrylic compounds are known and can be easily obtained by reacting a silicon compound with a compound having an aliphatic multiple bond in the presence of chloroplatinic acid. Silicone represented by general formula (a') and general formula (b')
The reaction with the acrylic compound shown in (1) proceeds smoothly by a conventional method to obtain a radically polymerizable silicone monomer. That is, when X of the acrylic compound is a chlorine atom, a dehydrochlorination reaction proceeds, and when X is a methoxy group or an ethoxy group, a dealcoholization condensation reaction proceeds.

The appropriate reaction ratio between silicone and acrylic compound is 0.25 to 1 mole of acrylic compound per mole of silicone. If it is less than 0.25 mol, a large amount of unreacted silicone will remain during the production of coating resin;
If the amount exceeds the molar amount, gelation tends to occur during the production of paint resin.

Furthermore, one method of producing a silicone polymer preferably used in the present invention is to use an acrylic compound represented by the following general formula (b'') in place of the acrylic compound represented by the general formula (b'). , other raw material compounds, reaction conditions, etc. are the same as the method disclosed in JP-A-58-154766 to synthesize a radically polymerizable silicone branch monomer (JP-A-59-20360). R
7 ○ (In the above general formula, n is an integer of 1 or 3, and the other meanings of R7, R8 and X are as in the above general formula (b')
It is the same as that in . ) The above-mentioned JP-A-58-154766 or JP-A-59
The product proposed in No. 20350, produced by the production of radically polymerizable silicone-based heptanomers, has silicone introduced into one molecule of an acrylic compound as its main component, along with unreacted raw material silicone and by-produced acrylic. Although it contains a polyfunctional silicone (such as one in which two molecules of an acrylic compound are introduced into one molecule of silicone) as a subsidiary component, this product can be used as it is as a radically polymerizable silicone-based heptanomer useful in the present invention. can be used.

The usage ratio of radically polymerizable silicone polymer is as follows:
It is preferably 3 to 60% by weight in the graft polymer, and 5 to 5% by weight.
0 weight is more preferred.

If the amount of the radically polymerizable silicone monomer used is less than 3% by weight, it will not be possible to obtain the desired graft polymer with excellent mold release properties; This is because, if it exceeds this value, the radical polymerizability becomes low, the mechanical strength of the coating also decreases, and the coating becomes expensive, which is not preferable.

The molecular weight of such branched polymers is generally between 500 and 400.
00 preferably iooo to 20000.

The number average molecular weight in the present invention is a polystyrene-equivalent molecular weight measured by GPC (gel permeation stomatagraphy).

Examples of radically polymerizable heptanomers constituting the backbone polymer used in the present invention include the following.

Examples of olefinic compounds include low molecular weight unsaturated hydrocarbons such as ethylene and propylene; vinyl halides such as vinyl chloride and vinyl fluoride; vinyl esters of organic acids such as vinyl acetate; styrene, styrene substitutes, and vinylpyridine; Vinyl aromatic compounds such as vinylnaphthalene; acrylic acid, methacrylic acid, and derivatives thereof, such as methyl acrylate 1-, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, 2-ethylhexyl acrylate , esters and amides such as fluoroalkyl acrylate and fluoroalkyl methacrylate; N-vinyl compounds such as acrylonitrile, acrylonitrile, N-vinylpyrrolidone and N-vinylprolactam; disubstituted ethylenes such as vinylidene fluoride and vinylidene chloride; Examples include esters of maleic anhydride, maleic acid, and fumaric acid.

These radically polymerizable monomers can be used alone or in combination of two or more.

The graft polymer of the present invention is copolymerized by further including a radically polymerizable monomer having a hydrolyzable functional group bonded to a silicon atom or a radically polymerizable monomer having a hydroxyl method (hereinafter simply referred to as a "crosslinkable heptanomer"). It is also possible.

The crosslinkable monomer used in the present invention is a radically polymerizable monomer having a hydrolyzable functional group because of the need to improve the adhesion between the graft polymer and the coated material, water resistance, moisture resistance, and the strength of the polymer itself (Graph 1). It is a monomer or a radically polymerizable monomer having a hydroxyl group.

The hydrolyzable functional groups in the present invention include alkoxy groups, acetoxy groups, and those with the general formula (OC2H.) po R9 (R9 is a hydrogen atom, a methyl group, or an ethyl group, and P is 1 to 5
is an integer. ). Examples of radically polymerizable monomers having a hydrolyzable functional group include acrylate silanes and/or methacrylate silanes represented by the general formula Ril1U, and other radically copolymerizable silanes include Cl,=C}I+Si (R''), -nXn can be mentioned.

In these two general formulas, R'' is a hydrogen atom or a methyl group, R11 and R'' are a methyl group, an ethyl group, or a phenyl group, and n is an integer from 1 to 3. m is 0 or 1
, Q is an integer from O to 2 when m=o, and 2 when m=1. X is an alkoxy group, an acetoxy group, or a group represented by the general formula (OC, H,)poR" (R13 is a hydrogen atom, a methyl group, or an ethyl group, and p is an integer of 1 to 5). Specifics Specifically, γ-(meth)acryloyloxypyltrimethoxysilane, n-(meth)acryloyloxypylmethyldimethoxysilane, γ-(meth)acryloyloxypyldimethoxysilane, 3-(2-(
meth)acryloyloxyethoxy)propyltrimethoxysilane, 3-(2-(meth)acryloyloxyethoxy)purvylmethyldimethoxysilane. 3-
(2-(meth)acryloyloxyethoxy)probyldimethylmeth! -oxysilane, 5-((meth)acryloyloxy)pentyltrimethoxysilane, 6-((meth)acryloyloxy)pentylmethyldimethoxysilane, 5-((meth)acryloyloxy)pentyldimethylmethoxysilane, p-vinyl Phenyltrimethoxysilane, p-vinylphenyldimethylmethoxysilane, p-vinylphenyldimethylmethoxysilane, γ-(
Examples include meth)acryloyloxypropyltri(β-methoxyethoxy)silane.

Of these, γ-(meta) in terms of ease of acquisition and cost.
Acryloyloxypropyltri(β-methoxy)silane is preferred.

In addition, as the radically polymerizable monomer having a hydroxyl group, any radically polymerizable heptamer having a hydroxyl group can be used, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxyl methyl (meth)acrylate, etc. , 3-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate,
Examples include 2,3-dihydroxypropyl (meth)acrylate.

Among these radically polymerizable heptanomers, ease of acquisition,
2-hydroxyethyl (meth)acrylate is preferred in terms of cost.

When the crosslinking monomer is a radically polymerizable silicon compound having a hydrolyzable functional group, the proportion used thereof is preferably 0.1 to 30% by weight, and 0.5 to 30% by weight in the graft polymer.
20% by weight is more preferred. If the proportion of the crosslinking monomer used is less than 0.1% by weight, it will not be possible to improve the chemical resistance, heat resistance, or coating strength of the coating due to crosslinking and curing, and if it exceeds 30% by weight, the resistance of the coating will decrease. If the chemical properties, hardness, and heat resistance are not sufficiently improved, and a crosslinking curing catalyst is also used, the pot life may be shortened or it may be difficult to control the pot life.

When the crosslinking monomer is a radically polymerizable monomer having a hydroxyl group, the proportion of its use in the graft polymer is preferably 0.5 to 40% by weight, and 1 to 30% by weight.
is even more preferable. The reason is the same as in the case of the radically polymerizable silicon compound having a hydrolyzable functional group.

The method of radical copolymerization is a conventionally known method (Japanese Unexamined Patent Publication No.
-126478, JP-A-58-154766, JP-A-59-20360, etc.) can be used.
For example, a radiation irradiation method, a method using a radical polymerization initiator, etc. can be used, but a method using a radical polymerization initiator is preferable in terms of ease of polymerization operation and easy control of molecular weight. Polymerization method, bulk polymerization method,
Any method such as emulsion polymerization can be carried out, but solution polymerization is a method in which each monomer is uniformly dissolved in a solvent such as toluene or methyl isobutyl ketone (hereinafter referred to as rMIBKJ), and polymerization can be carried out uniformly. is preferred.

The graft polymer according to the present invention can be easily produced by radical copolymerization of a radically polymerizable branched polymer, a radically polymerizable heptamer, and a crosslinkable monomer using various polymerization methods such as those described above.

The graft polymer of the present invention may be used as it is after being dissolved in a solvent, or may be crosslinked as shown below.

Regarding the silane cross-linked curing type, the polymer solution obtained by the solution polymerization method can be used as is or further diluted with a diluting solvent such as toluene, and a commonly used silane coupling agent curing catalyst such as dibutyltin dilaurate or dibutyltin dilaurate can be used. If a small amount of maleate or the like is added, applied to the object to be coated, and dried, a crosslinked cured film with excellent mold release properties can be obtained. The crosslinking and curing of this film is caused by the hydrolyzable functional groups being crosslinked by moisture in the air.

Examples of catalysts that can be used to accelerate crosslinking include tin compounds such as the aforementioned dibutyltin laurate and dibutyltin maleade; acidic compounds such as phosphoric acid and p-toluenesulfonic acid; and amines such as ethylenediamine and 1-lyethylenetetramine. The amount used is 0.001 to 10% by weight, preferably 0.001 to 10% by weight, based on the coating resin. oi
~8% by weight.

Next, let's talk about hydroxyl group cross-linked curing types: toluene, MIBK, methyl ethyl ketone (rMEKJ)
It is diluted with a solvent such as (referred to as ), polyvalent incyanates are added, applied to the object to be coated, and dried.

Examples of polyvalent isocyanates include tolylene diisocyanate, xylylene diisocyanate, and ? xamethylene diisocyanate, inphorone diisocyanate, methylene bis(4-cyclohexyl isocyanate) quintic formula CH, CI2C (CIl OCONII (CI+
2) s NCO), and/or the like, and these can be used alone or in combination of two or more.

When curing at room temperature using incyanates,
It is also possible to accelerate curing by adding known catalysts such as dibutyltin dilaurate. The amount of polyvalent isocyaner 11 used as a curing agent is based on the hydroxyl group It (OH equivalent) based on the above-mentioned hydroxyl group-containing radically polymerizable monomer in the graft polymer of the present invention.
is determined according to the

Furthermore, the hydroxyl group-crosslinked curable graft polymer of the present invention can be cured by heating using a melamine curing agent, a urea-based curing agent, a polybasic acid curing agent, etc., which are used in ordinary heat-curing acrylic paints. An excellent mold release coating agent with excellent physical properties (adhesion, water resistance, moisture resistance, solvent resistance, heat resistance, strength, etc.) equivalent to those obtained by curing with polyvalent isocyanate can be obtained. Examples of the melamine curing agent include butylated melamine, methylated melamine, epoxy-modified melamine, and the like. Examples of the urea-based curing agent include methylated urea and butylated urea. Further, as the polybasic acid curing agent, long-chain aliphatic dicarboxylic acids, aromatic polycarboxylic acids, or anhydrides thereof, etc. are useful.

When using melamine or urea hardeners, curing is accelerated by the addition of an acidic catalyst.

The molecular weight of the graft polymer used in the present invention is 5000~
Approximately 200,000 is preferable. If the molecular weight of the graft polymer is less than 5,000, the strength of the resulting film will be weak, and if it exceeds 200,000, the viscosity will be too high, causing problems in coating properties, which is not preferred.

Conventional methods such as gravure coating, reverse roll coating, roll coating, and air knife coating can be used to apply the stick prevention layer forming liquid onto the heat-sensitive layer. When the above-mentioned specific graft polymer is used, it can be cured with isocyanate, melamine resin, etc., if necessary.

The thickness of the anti-stick layer is o. oot to 1.5 μm, preferably 0.01 to 0.3 μm. If the thickness of the stick prevention layer is less than 0.001 μm, the mold release effect will not be sufficiently exhibited, and if it exceeds 1.5 μm, head residue adhesion will be hindered.

The release layer (stick prevention layer) of the present invention does not pose a problem when a fluororesin is used, and the branch polymer having a fluororesin or silicone resin as a backbone is on the side opposite to the heat-sensitive recording layer surface. On the other hand, since the backbone polymer is oriented toward the surface of the heat-sensitive recording layer, the stick prevention layer formed has good adhesion to the heat-sensitive recording layer. Since the fluorine or silicone skeleton structure is oriented, it has excellent head running properties and can suppress the adhesion of residue to the head even during a long printing process.

Next, examples and comparative examples will be shown. "Part" and r here
%" are based on weight.

Example 1 Behenic acid on a polyester film approximately 100 μm thick
4 parts stearyl stearate 1 part tetrahydrofuran
A solution consisting of 82 parts was applied with a wire bar and dried by heating to provide a heat-sensitive layer about 15 μm thick. On top of that, a solution consisting of 97 parts of isopropanol was added.
A reversible thermosensitive recording material was prepared by coating with a lawφ wire bar and drying to provide a stick prevention RiJ with a thickness of about 0.1 μm.

Example 2 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and a solution of 98 parts of hexane was applied thereon in the same manner as in Example 1 and dried to form an anti-stick layer with a thickness of approximately 0.1 μm. A reversible thermosensitive recording material was prepared.

Example 3 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and a solution of 97 parts of ethanol was applied thereon in the same manner as in Example 1 and dried to form a stick prevention layer with a thickness of approximately 0.1 μm. A reversible thermosensitive recording material was prepared.

Example 4 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, a heat-sensitive layer was provided on top of the heat-sensitive layer, and the resulting solution was applied thereon in the same manner as in Example 1 and dried to a coating of approximately 0.
A reversible thermosensitive recording material was prepared by providing a 1 μm thick anti-stick layer.

Example 5 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and water was added on top of it.
A solution consisting of 95 parts was applied in the same manner as in Example 1 and dried to form an anti-stick layer with a thickness of about 0.1 μm. A reversible thermosensitive recording material was created.

Example 7 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and water was added on top of the heat-sensitive layer.
A solution consisting of 6 parts was applied in the same manner as in Example 1 and dried to provide a stick prevention layer with a thickness of about 0.1 μm to prepare a reversible thermosensitive recording material.

Example 6 A polyester film was prepared in the same manner as in Example 1. A solution consisting of 1 part of dibutyltin dilaurate and 98 parts of methyl ether ketone was coated in the same manner as in Example 1 and dried to a coating of about 0.0
A reversible thermosensitive recording material was prepared by providing a 1 μm thick anti-stick layer. Example 8 Except that the acrylic silicone graph 1 polymer in Example 7 was replaced with a graphite polymer (molecular weight of about 50,000) of polytetrafluoroethylene (molecular weight about 5,000) and butyl acrylate whose one end is a methacrylate group. A reversible thermosensitive recording material was prepared in exactly the same manner as in Example 7.

Example 9 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and a methyl ethyl ketone-toluene mixed solution was added on top of the heat-sensitive layer.
A solution consisting of 3 parts was applied in the same manner as in Example 1 and dried to provide a stick prevention layer with a thickness of about 0.02 μm to prepare a reversible thermosensitive recording material.

Example 1.0 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and an acrylic silicone graft polymer (solid content 30%) was placed on top of it.
10 parts (Aron XS-703 manufactured by Toagosei Kagaku Kogyo Co., Ltd.) Isopropyl alcohol 90
A solution consisting of 50% of
．． A reversible thermosensitive recording material was prepared by providing an oi μm thick anti-stick layer.

Example 11 A thermosensitive layer was provided on a polyester film in the same manner as in Example 1, and methanol 9
A reversible heat-sensitive recording material was prepared by applying a solution consisting of 0 parts in the same manner as in Example 1 and drying to form a stick prevention layer having a thickness of about 0.01 μm.

Comparative Example 1 A comparative reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that the stick prevention layer was not provided.

Comparative Example 2 A heat-sensitive layer was provided on a polyester film in the same manner as in Example 1, and 10 parts of organopolysiloxane (S D7226 manufactured by Toray Silicone Co., Ltd.) and toluene were added thereon.
A comparative reversible thermosensitive recording material was prepared by applying a solution of 49.9 parts in the same manner as in Example 1 and drying to provide a stick prevention layer made of silicone rubber having a thickness of about 0.5 μm.

Comparative Example 3 A thermosensitive layer was provided on a polyester film in the same manner as in Example 1, and the sticking properties and the like were examined for 14 types of samples prepared as described above. The results are shown in Table 1. (Left below) Hardening agent (TSL-8331 manufactured by Toshiba Silicone Co., Ltd.) 0
．． A solution consisting of 2 parts and 10 parts of dioxane was applied in the same manner as in Example 1 and dried to an approximately O.
A comparative reversible thermosensitive recording material was prepared by providing an anti-stick layer made of a polysiloxane graft polymer with a thickness of lμI.

Table 1-2) The state of adhesion of head residue when continuous printing was performed for 300 meters using Ricoh's CUVAX MC50 was evaluated.

○ means that there is no residue attached, and X means that there is residue attached.

〔effect〕

As is clear from the description of Examples, the reversible thermosensitive recording material of the present invention has particularly excellent sticking properties and is suitable for long-term recording. In addition, since the surface is smooth, it adheres well to a thermal head, etc., and as a result, the thermal sensitivity is improved compared to the conventional one, making it possible to form clear images.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the recording and erasing principle of the reversible thermosensitive recording material of the present invention.

Claims (1)

[Claims] 1. A heat-sensitive layer whose main components are a resin base material and an organic low-molecular substance dispersed in the resin base material and whose transparency changes reversibly depending on the temperature is provided on the support, and further on the heat-sensitive layer, 1. A reversible thermosensitive recording material, comprising a stick prevention layer containing at least one selected from a fluorine-based mold release agent and a graft polymer having a silicone-based resin as a branch polymer.