JPH11138986A - Image forming material and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To upgrade a stability of a coating liquid even in the case of diluting it with a large quantity of a solvent without after-image color with high resolution by incorporating an image forming layer containing a ferromagnetic metal powder of a mean long axial length and a saturation magnetization amount of specific range and a binder on a support, thereby giving a sufficient density with a high sensitivity. SOLUTION: An image forming layer provided on a support contains a ferromagnetic metal powder having at least a mean long axial length (L) of 30<=L<=120 (nm) and a saturation magnetization (σs) of 125 to 170 emu/g and a binder. As the powder, a powder containing as constituent elements Fe, Al, Co and one or more types of rare earth element selected from Sm, Nd, Y, Pr and La is preferably used. And, the powder containing 2 to 20 pts.wt. of an Al atom, 10 to 60 pts.wt. of a Co atom, and 1 to 16 pts.wt. of a rare earth element based on 100 pts.wt. of an Fe element is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a high sensitivity and sufficient density, a high resolution, no residual color, and a large amount of a solvent for the purpose of increasing the wet film thickness in order to reduce coating unevenness of an image forming layer. The present invention relates to an image forming material having good stability of a coating solution even when diluted to a low concentration, and a method for producing the same.

[0002]

2. Description of the Related Art Hitherto, there has been known a recording method in which a recording material is irradiated with high-density energy light such as a laser beam so that a part of the material is melted, deformed, scattered, burned, or evaporated. These are dry treatments that do not require treatment liquids such as chemicals, and have the advantage that high contrast can be obtained by melting, deforming, or evaporating and removing only the light-irradiated portions, and have the advantage of being a resist material. , Optical recording materials such as optical disks, and image forming materials that make themselves visible images.

[0003] For example, Japanese Patent Application Laid-Open Nos.
JP-A-105638 and JP-A-62-115153 disclose a method of forming a resist pattern by photodecomposing a binder resin by pattern exposure and materials for the same, which are described in JP-A-55-132536, JP-A-57-27788, 57
JP-A-103137 discloses that an inorganic compound thin film provided by a vapor deposition method is exposed to light to record information by melting deformation of the film.
No. 87, No. 6-40163 and the like, a material for information recording by removing a colored binder layer by photothermal conversion,
U.S. Pat. No. 4,245,003 and the like each disclose an image forming material having an image forming layer containing graphite or carbon black.

Japanese Patent Application Laid-Open No. Hei 9-15849 has an image forming layer containing colorant particles and a binder, and the transmission density at a wavelength λmax at which the transmission density is maximum in a spectral absorption wavelength region of 350 to 1200 nm is a film thickness. 3.0 per μ
The above-described image forming materials are disclosed.

[0005]

Problems to be Solved by the Invention
By the technology disclosed in No. 5, high density with sufficient sensitivity was obtained, the residual color was also good, but coating unevenness needs to be improved, especially in the step of coating the image forming layer,
In order to reduce coating unevenness, there has been a problem that when diluted with a large amount of solvent to increase the wet film thickness, the dilution stability is not sufficient. In particular, when the dry film thickness of the image forming layer is 0.5 μm or less in order to improve the resolution, it is necessary to dilute the coating solution with a large amount of a solvent, but since the stability of the coating solution is not sufficient, sensitivity and There is a problem that the resolving power is reduced and a residual color is generated.

An object of the present invention is to provide a sufficient density with high sensitivity, high resolution and no residual color, and to increase the wet film thickness in order to reduce coating unevenness of the image forming layer. An object of the present invention is to provide an image forming material having good stability of a coating liquid even when diluted, and a method for producing the same.

[0007]

The above objects of the present invention have been attained by the following constitutions.

(1) An image forming layer containing a ferromagnetic metal powder and a binder is provided on a support, and the ferromagnetic metal powder has an average major axis length (L) of 30 ≦ L ≦ 120 (nm). An image forming material having a saturation magnetization (σs) of 125 to 170 emu / g.

(2) The ferromagnetic metal powder is composed of Fe atoms 1
2. The image forming material as described in 1 above, wherein the image forming material contains 10 to 60 parts by weight of Co atoms per 100 parts by weight.

(3) The ferromagnetic metal powder has Fe, Al, and Co as constituent elements, and Sm, Nd, Y, Pr
Or the 1, wherein the image forming material characterized by containing one or more rare earth elements selected from La (4) binder _{-SO 3 M, -OSO 3 M,} -CO
OM and —PO (OM ₁ ) ₂ (where M represents a hydrogen atom or an alkali metal, and M ₁ represents a hydrogen atom, an alkali metal or an alkyl group) and is a resin having at least one polar group. 2. The image forming material as described in 1 above, wherein

(5) The binder as described in any one of (1) to (4) above, wherein the binder comprises a polyurethane resin having the polar group, a vinyl chloride resin having the polar group, or a polyester resin having the polar group. The image forming material as described in the above.

(6) The image forming material as described in any one of (1) to (5) above, wherein the coating solution for the image forming layer is coated at a specific gravity at 20 ° C. of 0.90 to 0.97. Manufacturing method.

Hereinafter, the present invention will be described in detail.

<Image forming material> The image forming material of the present invention is characterized in that an image forming layer is provided on a support, and the transmission density or light transmittance per unit film thickness of the layer is in a specific range. And

As the support, acrylates, methacrylates, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, nylon, aromatic polyamide, polyether Resin films of ether ketone, polysulfone, polyethersulfone, polyimide, polyetherimide, etc., and further, resin films obtained by laminating two or more layers of the above resins can be exemplified.

In the present invention, the support is preferably stretched into a film and heat-set in view of dimensional stability. Further, when the image forming method described below is carried out, the support is irradiated with high-density energy light from the support side. When performing image exposure,
The transmittance for the wavelength of the energy light is preferably 50% or more, and more preferably 70% or more. Further, titanium oxide within a range not to impair the effects of the present invention,
Fillers such as zinc oxide, barium sulfate and calcium carbonate, coloring agents, antistatic agents and the like may be added.

The thickness of the support is about 10 to 500 μm,
Preferably it is 25 to 250 μm.

The image forming layer of the image forming material of the present invention has an average major axis length (L) of at least 30 ≦ L ≦ 120 (n).
m) and the saturation magnetization (σs) is 125 to 170 emu.
/ G of ferromagnetic metal powder and a binder.

Examples of the ferromagnetic metal powder particles include Fe and Co.
, Fe-Al-based, Fe-Al-Ni-based, Fe-A
l-Zn system, Fe-Al-Co system, Fe-Al-Ca
System, Fe-Ni system, Fe-Ni-Al system, Fe-Ni-
Co-based, Fe-Ni-Zn-based, Fe-Ni-Mn-based, F
e-Ni-Si system, Fe-Ni-Si-Al-Mn system,
Fe-Ni-Si-Al-Zn system, Fe-Ni-Si-
Al-Co system, Fe-Al-Si system, Fe-Al-Zn
System, Fe-Co-Ni-P system, Fe-Co-Al-Ca
, Ni-Co, and ferromagnetic metal powders such as metal magnetic powders containing Fe, Ni, Co, etc. as a main component. Among them, Fe-based metal powders are preferable. Also, from the viewpoint of corrosion resistance and dispersibility, among Fe-based metal powders, Fe-Al-based
e-Al-Ca system, Fe-Al-Ni system, Fe-Al-
Zn-based, Fe-Al-Co-based, Fe-Ni-Si-Al
-Co-based, Fe-Co-Al-Ca-based and other Fe-Al-based ferromagnetic powders are preferable, and among these, Fe, Al, and Co as constituent elements, and Sm, Nd, Y, P
Those containing one or more rare earth elements selected from r or La are preferred.

The shape of the ferromagnetic metal powder is such that the average major axis length (Lav) observed by a transmission electron microscope is 30 to
120 nm. Here, Lav is preferably 40-1.
It is 10 nm, more preferably 50 to 100 nm. L
By setting av in this range, even when diluted with a large amount of solvent, a coating solution that does not cause shock, maintains good dispersibility, and has a large amount of creep deformation, and has rheological characteristics suitable for multilayer coating is obtained. can get.

At this time, the crystallite size (Sa) determined by X-ray diffraction is preferably 5 ≦ Sa ≦ 17 (nm), more preferably 6 ≦ Sa ≦ 15 (nm). When the crystallite size is in this range, a sufficient record can be obtained.

In the present specification, the average major axis length is an average value obtained by measuring 500 major axis lengths of ferromagnetic powder or nonmagnetic powder by a transmission electron micrograph. The axial ratio was determined by measuring the average major axis length and average minor axis length of 500 particles in an electron micrograph (average major axis length / average minor axis length). The crystallite size was measured by an X-ray diffractometer using the integrated width of the (110) diffraction line of Fe by the Scherrer method based on Si powder.

The shape and axial ratio of the magnetic powder can be controlled by combining known methods such as selection of a starting material as a starting material, selection of oxidation-reduction conditions, selection of a sintering inhibitor and the like. it can.

The ferromagnetic metal powder according to the present invention comprises Fe, Al, Co and Sm, Nd and Y in the overall composition.
And the abundance ratio of one or more rare earth elements selected from the group consisting of Pr and La is based on 100 parts by weight of Fe atoms.
Al atom is 2 to 20 parts by weight, Co atom is 10 to 6 parts by weight.
0 parts by weight, and one or more rare earth elements selected from the group consisting of Sm, Nd, Y, Pr, and La are preferably 1 to 16 parts by weight. In addition, F on the surface
e, Al, Co, and the abundance ratio of one or more rare earth elements selected from the group consisting of Sm, Nd, Y, Pr, and La are 70 to 3 with respect to 100 Fe atoms.
And the number of atoms of one or more rare earth elements selected from the group consisting of Sm, Nd, Y, Pr, and La is 0.5 to
A value of 50 is preferred.

The ferromagnetic metal powder further contains Na and Ca as its constituent elements, and contains Ca, Ba, Sr, M
g, the total abundance of one or more elements selected from
It is preferably 0.001 to 20 parts by weight based on 100 parts by weight of e atom. Further, the ferromagnetic metal powder further contains Ni and Si as its constituent elements,
Ni atoms are 2 to 20 parts by weight with respect to 0 parts by weight,
The Si atom is preferably used in an amount of 0.01 to 5 parts by weight. It is preferable to select the above-mentioned element as a constituent element of the ferromagnetic metal powder, since it is excellent in the effect of preventing sintering, makes the magnetic powder fine, and increases the saturation magnetization (σs).

The content of the ferromagnetic metal powder is usually 60 to 95% by weight based on the total solid content in the layer.
And preferably 70 to 90% by weight.

The ferromagnetic metal powder uses iron oxyhydroxide obtained by blowing an oxidizing gas into an aqueous suspension in which a ferrous salt and an alkali are mixed, as a starting stock solution. Such an iron oxyhydroxide may be obtained by reacting an aqueous solution of ferrous salt with an aqueous alkali solution to obtain an aqueous solution containing ferrous hydroxide, and oxidizing the aqueous solution by air oxidation or the like. preferable. As the type of the iron oxyhydroxide, α-F
eOOH is preferred. As a production method, a ferrous salt is neutralized with an alkali hydroxide to form an aqueous suspension of Fe (OH) ₂ , and an oxidizing gas is blown into the suspension to obtain acicular α-OH. F
There is a first manufacturing method for eOOH. Here, the needle shape means one having (average major axis length / average minor axis length) of 2 to 20.
On the other hand, there is a second production method in which a ferrous salt is neutralized with an alkali carbonate to form an aqueous suspension of FeCO ₃ , and an oxidizing gas is blown into the suspension to form a spindle-shaped α-FeOOH. The spindle-shaped α-FeOOH is described in, for example, JP-A-6-1808.
No. 37 can be used. At this time, Ni salt, Ca salt, Ba salt, S
A salt of an alkaline earth element such as an r salt, a Cr salt, a Zn salt, or the like may coexist, and the particle shape and the like can be controlled by appropriately selecting and using such a salt.

As the ferrous salt, ferrous chloride, ferrous sulfate
Iron and the like are preferred.

As the alkali, NaOH, NH ₄ O
H, (NH ₄ ) ₂ CO ₃ , Na ₂ CO _{3 and the} like are preferable. Further, as the Ni salt, a Ca salt, a Ba salt, a nickel salt or the like,
As the Sr salt, chlorides such as calcium chloride, barium chloride, and strontium chloride are preferable. The following operation is performed using the above-mentioned slurry using the above-mentioned hydrous iron oxide as a starting material.

When Co is introduced into the magnetic powder, A
Before introducing l and / or Si and a rare earth element, specifically, a Co compound such as cobalt sulfate or cobalt chloride is used, and this aqueous solution is stirred and mixed with the slurry of iron oxyhydroxide.

Next, Al and / or Si are introduced in the following manner. That is, preferably, after preparing a slurry of iron oxyhydroxide containing Co, an aqueous solution containing an Al compound and / or a Si compound and an aqueous solution containing a compound of a rare earth element are added to the slurry, followed by stirring. What is necessary is just to mix.

The concentration of the aqueous solution containing the Al compound and the Si compound may be 0.5 to 1.5 M, and may contain only one of the compounds, or may contain both compounds. In this case, the total amount may be within the above range.

Examples of the Al compound used include sodium aluminate and sodium metaaluminate, and examples of the Si compound include sodium silicate.

The rare earth elements introduced in the present invention include Sm, Nd, Y, Pr and La.

Examples of the rare earth element compound used for preparing the above aqueous solution include chlorides such as neodymium chloride, samarium chloride, praseodymium chloride, lanthanum chloride and yttrium chloride, and nitrates such as neodymium nitrate. Further, two or more rare earth elements may be used in combination.

In order to introduce Al, Si and rare earth, it is preferable to separately prepare and add an aqueous solution containing Al and / or Si and an aqueous solution containing a rare earth element as described above. May be prepared by adding an aqueous solution containing Al and / or Si and a rare earth element.

In the embodiment of separately preparing and adding, both the solutions may be added at the same time, or one solution may be added and then the other solution may be added.
Alternatively, it is preferable to add an aqueous solution containing a rare earth element first after an aqueous solution containing Si.

In this way, the iron oxyhydroxide into which Al, Si and rare earth are introduced is sufficiently washed with water, dried, and heat-treated at a temperature of 300 to 800 ° C. in a non-reducing atmosphere. When the heat treatment temperature is 300 ° C. or less, α-FeOOH
Of the α-Fe ₂ O ₃ particles generated by dehydration of the ferromagnetic metal powder increases, resulting in inferior properties of the reduced ferromagnetic metal powder. If the heat treatment temperature exceeds 800 ° C., the melting of the α-Fe ₂ O ₃ particles starts, the shape of the particles changes, or sintering proceeds, and the characteristics of the resulting ferromagnetic metal powder are to degrade. Next, the ferromagnetic metal powder after the heat treatment is reduced at a temperature of 300 to 600 ° C. in a hydrogen gas stream, and an oxide film is formed on the surface by a known method to obtain a ferromagnetic metal powder.

The coercive force (Hc) of the ferromagnetic metal powder is 600
About 5000 Oersted, preferably 1500 to 3
000 Oersted and the saturation magnetization (σs) is 125
~ 170 emu / g, but 130 ~ 150 emu / g
And more preferably 130 to 145 emu / g. Specific surface area by BET method is 3
It is preferably 0 m ² / g or more.

The image forming layer preferably contains colorant particles having an absorption within a known wavelength range of 350 to 1200 nm together with the ferromagnetic metal powder of the present invention. One type of colorant particles may be used alone, or a plurality of types may be used in combination. Further, when an image is formed by an image forming method for reducing the bonding force with a support with high-density energy light described below, a compound having absorption in a wavelength range of 600 to 1200 nm as a colorant particle (hereinafter, referred to as a colorant particle). It is preferable to contain at least one kind of photothermal conversion compound). And the ferromagnetic metal powder of the present invention functions as a photothermal conversion compound.

Further, as the photothermal conversion compound, an organic compound and / or an inorganic compound can be appropriately selected and used. As the organic compound, for example, 600 to 1200 n
dyes and dyes dispersed in the image forming layer having absorption in the wavelength range of m. Specific examples include cyanine dyes, rhodocyanine dyes, oxonol dyes, carbocyanine dyes, and dicarbocyanine dyes. And tricarbocyanine dyes, tetracarbocyanine dyes, pentacarbocyanine dyes, styryl dyes, pyrylium dyes, and metal-containing dyes such as metal phthalocyanines and metalloporphyrins. Rev .. 92, 1197 (1
992) and the like. or,
Examples of inorganic compounds that absorb in the wavelength range of 600 to 1200 nm include graphite, carbon black, metal powder particles such as iron, nickel, zinc, titanium, aluminum, molybdenum, tungsten, copper, lead, and tin; Powder particles of alloys such as iron-cobalt, lead-tin, etc., metal oxide powder particles such as cobalt trioxide, iron oxide, chromium oxide, copper oxide, titanium black, metal nitride powder such as niobium nitride, tantalum carbide, etc. Metal carbide powder, metal sulfide powder, etc., and various magnetic powder particles used for magnetic paints and the like can also be suitably used in the present invention.

The above-mentioned colorant particles are present in the image forming layer in a state where the colorant particles are uniformly dispersed in the layer, and the colorant particles themselves are not porous. This is preferable because an image having a low residual ratio of the image forming layer to be removed when an image is formed by high-density energy light can be obtained.

The content of the colorant particles contained in the image forming layer is about 70 to 99% by weight, preferably 75 to 95% by weight of the components for forming the image forming layer.

As long as the binder can sufficiently hold the ferromagnetic metal powder of the present invention and the colorant particles, etc.,
It can be used without particular limitation.

Typical examples of such a binder include vinyl chloride resins such as polyurethane, polyester, and vinyl chloride copolymer.
_{O 3 M, -OSO 3 M,} -COOM and -PO (OM _{1) 2}
[Here, M represents a hydrogen atom or an alkali metal, and M ₁ represents a hydrogen atom, an alkali metal or an alkyl group. It is preferable that the resin has at least one kind of polar group selected from the following], and by using a resin having such a polar group introduced therein, the dispersibility of the colorant particles can be improved.
Incidentally, the content ratio of this polar group in each resin is 0.1 to 8.0.
Mol%, preferably about 0.2 to 6.0 mol%.

As the polar group-containing vinyl chloride, for example,
Vinyl chloride - a resin having a vinyl alcohol copolymer _{hydroxyl, Cl-CH 2 CH 2 SO} 3 M, Cl-CH 2 CH
_{2 OSO 3 M, Cl-CH} 2 CO 2 M, Cl-CH 2 P (=
O) It can be synthesized by an addition reaction with a compound having a polar group such as (OM ₁ ) ₂ and a chlorine atom. One example is shown below.

-CH ₂ C (OH) H- + Cl-CH ₂
CH ₂ SO ₃ Na → —CH ₂ C (OCH ₂ CH ₂ SO ₃ N
a) H-Polar group-containing vinyl chloride resin is prepared by charging a predetermined amount of a reactive monomer having an unsaturated bond into which a repeating unit containing a polar group is introduced into a reaction vessel such as an autoclave, and adding benzoyl peroxide, azobisisobutyl General radical polymerization initiators such as butyronitrile, and redox polymerization initiators,
It can be obtained by polymerization using a cationic polymerization initiator or the like. Specific examples of the reactive monomer for introducing sulfonic acid or a salt thereof include vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, p- Examples include unsaturated hydrocarbon sulfonic acids such as styrene sulfonic acid and salts thereof. When a carboxylic acid or a salt thereof is introduced, for example, (meth) acrylic acid or maleic acid is used, and when a phosphoric acid or a salt thereof is introduced, (meth) acryl-2-phosphate may be used.

Further, in order to improve the thermal stability of the binder, it is preferable to introduce an epoxy group into the vinyl chloride copolymer. In this case, the content of the repeating unit having an epoxy group in the copolymer is 1 to 30 mol%.
And preferably 1 to 20 mol%, and glycidyl acrylate can be used as a monomer for introducing an epoxy group.

The polyester having a polar group can be synthesized by a dehydration condensation reaction between a polyol and a polybasic acid partially having a polar group. Examples of the polybasic acid having a polar group include 5-sulfoisophthalic acid, -Sulfoisophthalic acid, 4-sulfoisophthalic acid, 3-sulfophthalic acid, 5
-Dialkyl sulfoisophthalate, dialkyl 2-sulfoisophthalate, dialkyl 4-sulfoisophthalate,
Examples thereof include dialkyl 3-sulfophthalates and alkali metal salts thereof. Examples of the polyol include trimethylolpropane, hexanetriol, glycerin, trimethylolethane, neopentyl glycol, pentaerythritol, ethylene glycol, propylene glycol, and 1,3-butane. Examples thereof include diol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and cyclohexanedimethanol.

The polyurethane having a polar group can be synthesized by reacting a polyol with a polyisocyanate. Specifically, a polyurethane obtained by reacting a polyol with a polybasic acid partially having a polar group as the polyol is obtained. It is synthesized by using the obtained polyester polyol as a raw material. Examples of the polyisocyanate include diphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, and lysine isocyanate methyl ester. As the other synthetic methods of the polyurethane having a polar _{group, Cl-CH 2 CH 2 SO} 3 M with polyurethane and polar group and a chlorine atom with a hydroxyl group, Cl-CH ₂ CH
_{2 OSO 3 M, Cl-CH} 2 CO 2 M, Cl-CH 2 P (=
An addition reaction with a compound such as O) (OM ₁ ) ₂ is also effective.

The binder may be used alone or in combination of two or more kinds. When two or more kinds are used in combination, for example, the ratio of the polyurethane and / or polyester to the vinyl chloride resin is 90:10 to 10:10. The ratio is 10:90, preferably 70:30 to 30:70.

In the present invention, a binder obtained by combining the above polyurethane resin having a polar group with the above vinyl chloride resin having a polar group or the above polyester resin having a polar group is preferable.

As another binder, vinyl chloride
Vinyl chloride resins such as vinyl acetate copolymer, polyolefin resins such as butadiene-acrylonitrile copolymer, polyvinyl acetal resins such as polyvinyl butyral, cellulose resins such as nitrocellulose, and styrene such as styrene-butadiene copolymer. A resin, an acrylic resin such as polymethyl methacrylate, a polyamide, a phenol resin, an epoxy resin, a phenoxy resin, or the like may be used in combination.

The content of the binder in the image forming layer is about 1 to 30% by weight, preferably 5 to 25% by weight in the components for forming the image forming layer.

The image forming layer may contain additives such as a lubricant, a durability improver, a dispersant, an antistatic agent, a filler, a filler, and a curing agent as long as the effects of the present invention are not impaired. Good.

Examples of the lubricant include fatty acids, fatty acid esters, fatty acid amides, (modified) silicone oils, (modified) silicone resins, fluororesins, and carbon fluorides. Can be mentioned. Examples of the dispersant include those described in paragraph No. 0093 of JP-A-4-214218, and examples of the antistatic agent include cationic surfactants, anionic surfactants, and nonionic surfactants. Agents, polymeric antistatic agents, conductive fine particles, etc., and “11290 Chemical Products”, Chemical Daily, p. 875
To 876 and the like.
Fillers include carbon black, graphite,
TiO ₂ , BaSO ₄ , ZnS, MgCO ₃ , CaCO ₃ ,
ZnO, CaO, WS ₂ , MoS ₂ , MgO, SnO ₂ ,
Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, SiC, C
eO ₂ , BN, SiN, MoC, BC, WC, titanium carbide, corundum, artificial diamond, garnet,
Examples include inorganic fillers such as garnet, silica stone, triboli, diatomaceous earth, and dolomite, and organic fillers such as polyethylene resin particles, fluorine resin particles, guanamine resin particles, acrylic resin particles, silicon resin particles, and melamine resin particles.

Further, as the curing agent, any one can be used without particular limitation as long as it can cure the image forming layer. Such a curing agent is, for example, used when synthesizing the polyurethane in the binder described above. The polyisocyanate used can be mentioned.

By hardening the image forming layer by adding such a curing agent, not only the durability of the formed image is improved, but also the residual color of the image forming layer portion removed by the image forming method described later. Can be eliminated.

The amount of these additives is about 0 to 20% by weight, preferably 0 to 15% by weight.

The thickness of the image forming layer is 0.1 to 5.0 μm
Degree, preferably in the range of 0.1 to 2.0 μm, particularly preferably 0.1 to 1.0 μm, and more preferably 0.2 to 1.0 μm.
0 μm. Within this range, in the image forming method described later, an image can be formed with irradiation of low-energy high-density energy light, in other words, with high sensitivity. Further, the image forming layer may be formed as a single layer, or may be formed as a multilayer having the same or different composition. When the image forming layer is formed as a multilayer, the image forming layer near the support may contain a photothermal conversion compound. It is preferable in terms of sensitivity.

Further, when the image forming layer of the present invention having the above composition is removed by the image forming method described below, the thickness of the image forming layer is as thin as possible from the viewpoint of resolution. Although it is preferable, in order to efficiently utilize the high density energy beam, when the maximum absorption wavelength in the spectral absorption wavelength region 350~1200nm a lambda _max, of at least the maximum absorption wavelength lambda image forming layer in _max film The transmission density per 1 μm thickness is 3.0 or more, preferably 3.5 or more, more preferably 4.0 or more, and the transmission density at the wavelength of high density energy light is 3.0 or more per 1 μm thickness. It needs to be.
Further, the transmittance per 1 μm of film thickness at the minimum transmittance wavelength λ _min in the wavelength region is 0.1% or less, preferably 0.1% or less.
It is not more than 05%, further not more than 0.03%.

The image-forming material of the present invention may be used in accordance with the purpose, if antistatic, transportability, anti-blocking, etc. are required on the back surface of the support in addition to the above-mentioned support and image forming layer. It is preferable to provide a backing layer, which may be coated with a commercially available backing layer-forming composition, or may be provided in advance on a support, and when newly provided, a known backing layer according to various purposes may be appropriately provided. It can be provided selectively.

Further, as long as the effects of the present invention are not impaired,
When the bonding force between the support and the image forming layer, the coating property of the image forming layer provided by coating or the antistatic of the image forming material, etc. are required, it is preferable to provide an intermediate layer or the like according to each purpose, Known intermediate layers for various purposes can be appropriately selected and provided.

The thickness of such an intermediate layer or backing layer is
The thickness is about 0.05 to 10 μm, preferably 0.1 to 5 μm.

In the image forming method of the present invention described below,
A release layer provided for transferring an image by peeling after image exposure is used as a release layer by forming a layer with a resin having self-supporting property or using a resin film used as a support as described above as a release layer. . An adhesive layer may be provided between the release layer and the image forming layer.

Such an adhesive layer may be any of those which have adhesiveness at room temperature themselves, and those which exhibit adhesiveness by applying heat or pressure. For example, a resin having a low softening point, an adhesiveness-imparting agent, It can be formed by appropriately selecting a thermal solvent.

Examples of the resin having a low softening point include ethylene copolymers such as ethylene-vinyl acetate and ethylene-ethyl acrylate; polystyrene resins such as styrene-butadiene, styrene-isoprene and styrene-ethylene-butylene; polyester resins; Polyolefin resins such as polyethylene and polypropylene; polyvinyl ether resins; acrylic resins such as polybutyl methacrylate;
Ionomer resins; cellulosic resins; epoxy resins; vinyl chloride resins such as vinyl chloride-vinyl acetate copolymers, and the like. Examples of the adhesion-imparting agent include rosin, hydrogenated rosin, rosin maleic acid, polymerized rosin and Unmodified or modified products such as rosin phenol, terpenes, petroleum resins and modified products thereof, and the like. Examples of the heat solvent include compounds that are solid at ordinary temperature and reversibly liquefy or soften when heated.Specifically, terpineol, menthol, acetamide, benzamide, coumarin, benzyl cinnamate, diphenyl ether, crown ether, Monomolecular compounds such as camphor, p-methylacetophenone, vanillin, dimethoxybenzaldehyde, p-benzylbifevir, stilbene, margaric acid, eicosanol, cetyl palmitate, stearamide, and behenylamine, beeswax, candelilla wax, and paraffin wax , Ester wax, montan wax, carnauba wax, amide wax, polyethylene wax, microcrystalline wax and other waxes, ester gum, rosin maleic resin, rosin phenol Rosin derivatives such as fats, phenolic resins, ketone resins, epoxy resins, diallyl phthalate resins, terpene hydrocarbon resins, cyclopentadiene resins, polyolefin resins, polycaprolactone resins, polyolefin oxides such as polyethylene glycol and polypropylene glycol, etc. And the like.

The thickness of the release layer is about 0.1 to 100 μm,
The thickness is preferably 0.5 to 50 μm, and the thickness of the adhesive layer is about 0.1 to 40 μm, preferably 0.3 to 30 μm.

In the present invention, an antistatic agent is added to any one of the above-mentioned support, image forming layer, backing layer, intermediate layer, release layer and adhesive layer for the purpose of preventing blocking and adhesion of dust. Is preferred. As such an antistatic agent, those added to the image forming layer can be appropriately selected and used.

The image forming layer has an average major axis length (L) of 30 ≦ 30.
L ≦ 120 (nm) and saturation magnetization (σs) is 125
A coating solution containing -170 emu / g ferromagnetic metal powder and a binder and having a specific gravity at 20 ° C adjusted to a range of 0.90 to 0.97 is applied on a support and dried. The coating liquid is, for example, kneading a colorant particles, a lubricant, a durability improver, a dispersant, an antistatic agent, a filler, a filler, a curing agent, and a solvent to prepare a high-concentration paint. Then, the high-concentration paint is diluted to give a coating for coating, applied on a support and dried to form a coating.

Examples of the solvent include alcohols (ethanol, propanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve), aromatics (toluene, xylene, chlorobenzene, etc.), ketones (acetone, methyl ethyl ketone, etc.), and esters. Use of solvents (such as ethyl acetate and butyl acetate), ethers (such as tetrahydrofuran and dioxane), halogen solvents (such as chloroform and dichlorobenzene), and amide solvents (such as dimethylformamide and N-methylpyrrolidone). Can be. Further, for kneading and dispersing the components of the image forming layer, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a cobol mill, a tron mill, a sand mill, a sand grinder,
Sqegvari Attritor, High Speed Impeller Disperser, High Speed Stone Mill, High Speed Impact Mill, Disper,
A high-speed mixer, a homogenizer, an ultrasonic disperser, an open kneader, a continuous kneader, or the like can be used.

The image-forming layer can be formed on the support by, for example, coating and drying with an extrusion-type extrusion coater. A calendering treatment may be performed to make the orientation of the magnetic powder particles uniform or to make the surface properties of the image forming layer uniform. Alternatively, the magnetic powder particles may be randomly oriented by performing a non-orientation treatment. Through these processes, a high-resolution image can be obtained.

For the orientation treatment, for example, after coating, a magnetic field is passed through a magnet for horizontal orientation, a magnet for vertical orientation, or a non-oriented magnet, introduced into a drier, and dried by blowing hot air from nozzles arranged above and below. It can be done by doing. Further, the calendering can be performed, for example, by guiding the support having the dried image forming layer to a super calendering apparatus, and performing calendering here.

The magnetic field generated by the magnet for horizontal orientation, the magnet for vertical orientation, or the non-oriented magnet is about 20 to 10000 gauss. The calendering conditions are usually about 50 to 140 ° C., the linear pressure is 50 to 400 kg / cm, and the transfer speed is 20 to 100 kg / cm. 1000m
/ Min, and drying at a temperature of about 30 to 120 ° C.
Perform in about ten minutes.

Further, when the content of the metal atom-containing particles is large in the image forming layer of the present invention, voids are easily formed in the image forming layer. In such a case, it is better to reduce the gap by applying pressure as necessary, such as a calendering process or a pressing process, if the image of the part where the exposed part was removed by image exposure with high-density energy light was removed. The residual ratio of the formation layer can be reduced.

In any case, in order to reduce the residual ratio, the porosity of the image forming layer is 30% or less, preferably 20%.
% Of the image forming material is preferably subjected to pressure treatment. The porosity can be measured by a mercury intrusion method using a porosimeter.

In the case where the above pressure treatment is not performed,
By randomly aligning the magnetic powder particles by a non-alignment treatment or the like, it is possible to reduce the residual ratio of the image forming layer in the portion where the exposed portion is removed when the image is exposed to high-density energy light. In this case, the porosity of the image forming layer may be 30% or more. Further, the metal atom-containing particles cannot be unconditionally determined by the specific gravity of the particles themselves or the above-mentioned porosity in the image forming layer, but is preferably 20 to 80% by volume, preferably 50 to 80% by volume. Here, the volume% is determined by the following method.

Volume% = (theoretical volume obtained from the weight of the metal atom-containing particles per unit area and the density of the metal atom-containing particles / the volume of the image forming layer per unit area obtained from the measured film thickness) × 100 When another layer besides the image forming layer is provided on the same side as the image forming layer, the coating and drying may be repeated for each layer, but may be performed by multi-layer coating by a wet-on-wet method and dried. . In that case, it can be applied by a combination of a reverse roll, a gravure roll, an air doctor coater, a blade coater, an air knife coater, a squeeze coater, an impregnation coater, a bar coater, a transfer roll coater, a kiss coater, a cast coater or a spray coater and an extrusion coater. it can.

In the multi-layer coating in the wet-on-wet method, the upper layer is coated while the lower layer is kept wet, so that the adhesion between the upper and lower layers is improved.

When the release layer is laminated on the image forming layer, if the release layer is a resin having a self-supporting property, the release layer forming resin is dissolved in a solvent and applied and dried in the same manner as the image forming layer. The layer forming resin may be melt-kneaded and provided on the image forming layer by extrusion lamination. When a resin film such as that used for a support is used as a release layer, a film having heat sealing properties such as polyethylene or polypropylene may be formed by laminating an image forming layer surface and a film and applying a heat roll. A release layer can be formed by heat and pressure using a hot stamp. When a film having no heat sealing property is used, an adhesive layer is provided on the image forming layer and the films are laminated. That is, the adhesive layer forming composition is applied and dried on the image forming layer to laminate the resin film, or the adhesive layer forming composition is applied and dried on the resin film, or the adhesive layer forming composition is heated and melted and extrusion lamination is performed. After that, the surface of the adhesive layer is superimposed on the image forming layer, and bonded by a heat and pressure treatment using a heat roll or a hot stamp to form a release layer. As the heat treatment, with a heat roll, room temperature to about 180 ° C., preferably 30 to 160 ° C.,
About 20 kg / cm, preferably 0.5 to 10 kg / cm
cm pressure, speed 1-200 mm / sec, preferably 5
This is performed while conveying at a speed of 100 mm / sec. When using a hot stamp, the temperature is from room temperature to about 180 ° C., preferably 30 to 180 ° C.
At ~150 ℃, 0.05~10kg / cm ² or so, preferably at a pressure of 0.5 to 5 kg / cm ^2, 0.1 to 50
Heat for about seconds, preferably 0.5 to 20 seconds.

<Image Forming Method> In the present invention, an image can be formed by the following four methods based on the constitution of the image forming material described above.

-Image Forming Method 1- In the first image forming method, an image is formed by performing image exposure with high-density energy light from the support side of the image forming material and removing the image forming layer in the exposed portion. .

The image forming layer used here may be composed of one layer, or may be composed of two or more layers. When it is composed of two or more layers, for example, an image forming layer in which a colorant-containing layer having an absorption at 350 to 600 nm is laminated on a photothermal conversion compound-containing layer having an absorption at at least 600 to 1200 nm is exemplified. Can be.

The high-density energy light used for image exposure from the support side can be used without particular limitation as long as it is a light source capable of removing the exposed portion by any method. Among them, in order to obtain high resolution, electromagnetic waves whose energy application area can be narrowed down, particularly ultraviolet rays, visible rays, and infrared rays having a wavelength of 1 nm to 1 mm are preferable. As a light source to which such high-density energy light can be applied, , For example a laser,
Examples include a light-emitting diode, a xenon flash lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a tungsten lamp, a quartz mercury lamp, and a high-pressure mercury lamp. The energy applied at this time can be appropriately selected by adjusting the exposure distance, time, and intensity according to the type of the image forming material.

In the case where the high-density energy light is collectively exposed, a mask material in which a negative pattern of a desired exposure image is formed of a light-shielding material may be overlaid and exposed.

When an array type light source such as a light emitting diode array is used, or when a light source such as a halogen lamp, a metal halide lamp, or a tungsten lamp is controlled to be exposed by an optical shutter material such as a liquid crystal or PLZT, an image signal is used. It is possible to carry out the corresponding digital exposure. In this case, direct writing can be performed without using a mask material.

However, in this method, a new optical shutter material is required in addition to the light source. Therefore, in the case of digital exposure, it is preferable to use a laser as the light source.

When laser light is used as a light source,
It is possible to form a latent image by scanning light according to image data by squeezing light into a beam, and furthermore, by using a laser as a light source, it is easy to narrow the exposure area to a very small size, and it is possible to form a high-resolution image Formation is possible.

As the laser light source used in the present invention, generally known ruby laser, YAG
Laser, glass laser and other solid lasers; He-N
Gas lasers such as e laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He-Cd laser, N ₂ laser, excimer laser; InGaP laser, AlGaAs laser, Ga
Semiconductor lasers such as an AsP laser, an InGaAs laser, an InAsP laser, a CdSnP ₂ laser, and a GaSb laser; chemical lasers, dye lasers and the like; It is preferable to use a laser having a wavelength of 600 to 1200 nm in terms of sensitivity since light energy can be efficiently converted to heat energy. Further, among them, a laser of 750 to 1200 nm can efficiently convert light energy into heat energy.
It is more preferable in terms of sensitivity, and among them, it is particularly preferable to use a high illuminance laser as long as the laser has the same wavelength.

In the present invention, image formation is performed by exposing the image forming layer to high-density energy light after image exposure, and then removing the exposed portion by any method. If the light exposure energy is sufficient to completely destroy and scatter the image forming layer, it can be removed by suctioning the scattered material, in which case it is adjacent to the image forming layer. By providing the suction portion at the portion where the heat is to be removed, the suction portion can be efficiently removed.

Further, when the exposure energy of the high-density energy light does not completely destroy the image forming layer, for example, when the bonding force between the support of the exposed portion and the image forming layer is reduced, the above-mentioned case is adopted. In addition to the removal by suction, it can be removed by an image forming method 3 or 4 described later.

Here, the decrease in the bonding force means that the image forming layer completely scatters due to a physical or chemical change.
This includes phenomena such that the image forming layer is partially destroyed and / or scattered, the surface of the image forming layer is not destroyed, and a physical or chemical change occurs only in the vicinity of the support.

-Image Forming Method 2- In the second method, the image forming material is subjected to image exposure with high-density energy light from the support side to reduce the bonding strength between the support and the image forming layer in the exposed area. The image is formed by removing the image forming layer in the exposed portion.

Further, the decrease in the bonding force referred to here also means that the image forming layer is completely scattered due to a physical or chemical change.
This includes phenomena such as partial destruction and / or scattering of the image-forming layer, the surface of the image-forming layer not being destroyed, and physical or chemical changes occurring only in the vicinity of the support.

-Image Forming Method 3- In the third image forming method, an image is formed by performing high-density energy light image exposure from the support side using an image forming material having an image forming layer laminated on a support. Lowering the bonding strength between the exposed portion of the layer and the support, and contacting the image forming layer with the adhesive layer or the adhesive layer surface of an adhesive sheet having an adhesive layer or an adhesive layer on a substrate, thereby reducing the density of the image forming layer. In this image forming method of forming an image by transferring the exposed portion of the energy light to the adhesive sheet side, when the colorant layer is partially destroyed and / or scattered due to physical or chemical change, Like the image forming methods 1 and 2, the image forming layer remaining on the image exposed portion remaining on the pressure-sensitive adhesive sheet described later may be removed by suction. When such suction removal is difficult, it is preferable to adjust the exposure energy of the high-density energy light so that a physical or chemical change occurs only in the vicinity of the support.

As the adhesive sheet in this case, a commercially available adhesive sheet, a heat sealing material or a laminate material can be used as it is. Further, in order to press or heat and pressure treatment with the image forming material and the adhesive sheet facing each other,
It can be used without particular limitation as long as it can be pressurized or heated and pressurized without increasing the adhesiveness and mixing of bubbles and the like.
When pressure is applied, a pressure roll, a stamper, or the like can be used, and when heat and pressure treatment is performed, a thermal head, a heat roll, a hot stamp, or the like can be used.

The pressure when using a pressure roll is usually 0.1 to 20 kg / cm, preferably 0.5 to 10 k / cm.
g / cm, and the conveying speed is usually 0.1 to 200.
mm / sec, preferably 0.5 to 100 mm / sec,
The pressure when using a stamper is usually 0.05
-10 kg / cm ² , preferably 0.5-5 kg / c
m ² , and the pressurization time are usually 0.1 to 50 seconds, preferably 0.5 to 20 seconds. Further, the thermal head can be used as it is under the conditions used for ordinary melt transfer, sublimation transfer and the like. The heating temperature when using a heat roll is usually 60 to 200 ° C, preferably 80 to 180 ° C.
° C, and the pressure is usually 0.1 to 20 kg / c.
m, preferably 0.5 to 10 kg / cm, and the conveying speed is usually 0.1 to 200 mm / sec, preferably 0.5 to 100 mm / sec. The temperature is usually in the range of 60 to 200 ° C., preferably 80 to 150 ° C., and the pressure is usually 0.
05 to 10 kg / cm ² , preferably 0.5 to ⁵ kg / cm ²
cm ² and the heating time are usually 0.1 to 50 seconds, preferably 0.5 to 20 seconds.

[0098] The peeling method may affect the image formation, such as a peeling angle fixing method using a peeling plate or a peeling roll, or a manual peeling method in which the adhesive sheet and the image forming material are peeled off without being fixed by hand. If not, various peeling methods can be used.

In the above description, an image forming material in which a single image forming layer is provided on a support has been described. However, when the image forming layer is composed of two or more layers, the same applies to the above case. The bonding force between the support and the image forming layer adjacent to the support may be reduced, or when a plurality of image forming layers having different compositions are provided on the support, for example, a photothermal conversion compound is contained as a colorant. A first image forming layer, and 35
When the second image forming layer containing a compound having an absorption in the wavelength range of 0 to 1200 nm is provided in this order, the position for reducing the bonding force may be between the support and the first image forming layer. It may be between the first image forming layer and the second image forming layer. Further, an intermediate layer may be provided between the image forming layer and the support.

-Image Forming Method 4- In the fourth image forming method, image exposure with high-density energy light is performed from the support side using the above-described image forming material having the release layer laminated on the image forming layer. Reduce the bonding force between the support of the exposed portion of the image forming layer and the image forming layer,
The image forming is performed by transferring a portion of the image forming layer exposed to the high-density energy light to the release layer side by peeling the release layer.

In this method, the image forming methods 1 and 2 described above are used.
In the case of (3), at the time of image exposure with high-density energy light, scattering of the image forming layer may occur depending on the exposure conditions, but since the release layer is laminated on the image forming layer of the image forming material, The image can be formed without such scattering.

In this image forming method, the image forming material to be used is one in which the release layer and the image forming layer are bonded in advance.
In some cases, the release layer and the image forming layer are not adhered just because they are in close contact, and in the latter case, the composition of the adhesive layer,
Partial adhesion between the adhesive layer and the image forming layer, the adhesive layer contains a filler, etc., so that a minute gap is provided between the adhesive layer and the image forming layer, and heat conduction and support from the image forming layer By designing so as not to hinder the deformation of the image forming layer due to the decrease in the bonding force between the body and the image forming layer, it is possible to reduce the bonding force between the support and the image forming layer at the same time as the image exposure with high-density energy light. The part where the bonding force between the support of the image-exposed portion and the image-forming layer is reduced as it is adhered to the adhesive layer due to the generated heat and scattering, and the image is formed simply by peeling off, and after the image exposure After the image forming material is heated and pressurized, the release layer is peeled off, and a portion of the image forming layer in which the bonding force between the support and the image forming layer is reduced may be transferred to the release layer side.

In this method, when an image is exposed with high-density energy light in the case of the image forming method 1, 2 or 3, the image forming layer may be scattered depending on the exposure conditions. Since the release layer is laminated on the formation layer, the image can be formed without such scattering.

The image exposure with high-density energy light can be performed in the same manner as in the image forming method 1. The method of peeling off the image forming material and the release layer is also described in the image forming method 3.
The method of peeling off the image forming material and the adhesive sheet can be used as it is.

[0105]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto. In the following, “parts” means “parts by weight as active ingredients” unless otherwise specified.

Example 1 <Image-forming material> An image-forming material of the present invention and a comparative image-forming material were prepared by using a support, an image-forming layer and a release layer shown below. Each combination is shown in Table 1.

-Support- Support 1: Blue polyethylene terephthalate film having a thickness of 180 μm and both surfaces of which are anchor-coated Support 2: An antistatic layer is provided on one side having a thickness of 180 μm, and the lamination surface of the image forming layer is subjected to corona discharge treatment Blue polyethylene terephthalate film.

-Image Forming Layer- Image Forming Layer 1: The following composition is kneaded and dispersed using a kneader and a sand mill to prepare an image forming layer forming coating solution containing colorant particles, and extrusion coating. After applying on a support, a magnetic field orientation treatment is performed while the coating film is not dried, followed by drying.
A calendering treatment was performed at a pressure of 1 cm to form an image forming layer having a thickness of 0.3 μm. The specific gravity of the coating solution at 20 ° C. was 0.94.

100 parts of Fe—Al ferromagnetic metal powder (Fe: Al: Co: Y = 100: 10: 40: 8 (weight ratio)) (Hc: 2200 Oe, BET: 60 m ² / g, σs: 135 emu) / G, average major axis length: 60 nm, needle ratio: 5) Crystallite size: 10 nm Vinyl chloride resin containing potassium sulfonate group (manufactured by Nippon Zeon Co., Ltd., MR110) 10 parts Polyurethane resin containing sodium sulfonate group ( Toyobo Co., Ltd., UR8200) 10 parts Carbon black (number average particle diameter 90 nm) 1 part α-alumina (number average particle diameter 0.15 μ) 5 parts Stearic acid 1 part Butyl stearate 1 part Polyisocyanate compound (Japan Polyurethane Industry Co., Ltd., Coronate L) 5 parts Cyclohexanone 400 parts Methyl ethyl ketone 400 parts Toluene 400 .

Image forming layer 2: Fe-Al based ferromagnetic metal powder (Fe: Al: Co) same as image forming layer 1 except that 100 parts of the following ferromagnetic metal powder were used in image forming layer 1 : Y: Si = 100: 8: 30:
5: 2 (weight ratio)) (Hc: 2100 Oe, BET: 58 m ² / g, σ)
s: 130 emu / g, average major axis length: 80 nm, needle ratio: 6) Crystallite size: 11 nm.

Image forming layer 3: Fe-Al based ferromagnetic metal powder (Fe: Al: Co) which is the same as image forming layer 1 except that 100 parts of the ferromagnetic metal powder described below were used in image forming layer 1 : Nd: Si = 100: 8: 20:
5: 2 (weight ratio)) (Hc: 2100 Oe, BET: 58 m ² / g, σ)
s: 130 emu / g, average major axis length: 100 nm, needle ratio: 6) Crystallite size: 14 nm.

Image forming layer 4: Except that in the image forming layer 1, 30 parts of a sodium sulfonate-containing polyester resin (manufactured by Toyobo Co., Ltd., Byron 28SS) was used instead of 10 parts of the potassium chloride-containing vinyl chloride resin. Is the same as that of the image forming layer 1.

Image forming layer 5: Same as image forming layer 1 except that the thickness of image forming layer in image forming layer 1 was 0.5 μm.

Image forming layer 6: Same as image forming layer 1 except that calendering was performed in image forming layer 1 under the conditions of 100 ° C., 350 kg / cm, and pressure.

Image forming layer 7: The same as the image forming layer 1 except that 100 parts of the ferromagnetic metal powder described below were used as the ferromagnetic metal powder in the image forming layer 1 Fe—Ni-based ferromagnetic metal powder (Fe: Ni = 100) : 10 (weight ratio)) (Hc: 1800 Oe, BET: 55 m ² / g, σ)
s: 122 emu / g, average major axis length: 140 nm, needle ratio: 8) Crystallite size: 15 nm.

Image forming layer 8: The same Fe-Al based ferromagnetic metal powder (Fe: Al: Co) as in image forming layer 1 except that 100 parts of the ferromagnetic metal powder described below were used in image forming layer 1. : Y = 100: 10: 5: 8 (weight ratio)) (Hc: 2000 Oe, BET: 55 m ² / g, σ)
s: 122 emu / g, average major axis length: 140 nm, needle ratio: 8) Crystallite size: 15 nm.

-Release Layer- As a release layer, a transparent polyethylene terephthalate film of 25 μm [S10 manufactured by Diafoil Hoechst Co., Ltd.
0], a coating liquid for forming an adhesive layer having the following composition was applied and dried on the release layer to form an adhesive layer having a thickness of 4.0 μm. Then, the surface of the adhesive layer and the surface of the image forming layer of the release layer with the adhesive layer are opposed to each other, and a pressure roll (conveying speed: 30 mm
/ Sec at a pressure of 2.0 kg / cm) to produce an image forming material in which an image forming layer and a release layer are laminated in this order on a support in such a manner that bubbles do not enter.

Ethylene-vinyl acetate copolymer [Evaflex EV410, manufactured by DuPont-Mitsui Polychemicals Co., Ltd.] 3.0 parts Silicone fine particles [Toshiba Silicone Co., Ltd., Tospearl 145] 0.6 parts Toluene 90 parts Cyclohexanone 6 .4 parts <Image forming method> Semiconductor laser [LT0 manufactured by Sharp Corporation]
90MD, main wavelength: 830 nm], the image was exposed by focusing on the interface between the support and the image forming layer and performing scanning exposure from the support side. Next, the surface of the image forming layer of the image forming material and an adhesive tape [Scotch N, manufactured by 3M Company]
o. 845 book tape] with the pressure-sensitive adhesive layer facing the pressure-sensitive adhesive layer (pressure roll, conveyance speed; 30 mm / sec, pressure 3.0 kg / cm) so that air bubbles do not enter, and the image forming material is flattened. The adhesive tape is peeled off (peeling angle 90 °, peeling speed 40 mm / sec), and the image with high-density energy light is used to transfer the portion where the bonding force is reduced to the adhesive tape side to form an image. Was.

The sensitivity, the resolution of the formed image and the residual ratio of the portion where the image forming layer was transferred and removed were evaluated according to the following criteria. Table 1 shows the evaluation results.

-Sensitivity- Solid scanning exposure is performed so that an image of 0.5 mm × 0.5 mm is formed at a beam diameter of 4 μm, and the average exposure amount on the surface of the image forming material on which an image is formed (E: unit mJ / c
m ² ) was evaluated on a 5-point scale 5 ... E≤100 4 ... 100 <E≤250 3 ... 250 <E≤400 2 ... 400 <E≤600 1 ... 600 <E.

-Resolution- 1 mm when an image was formed by scanning exposure with a beam diameter of 4 μm and a scanning pitch of 4 μm with an average exposure amount on the surface of the image forming material.
The number of resolvable lines per unit (N) was evaluated in four steps: 4 ... 125 = N 3 ... 120≤N <125 2 ... 110≤N <120 1 ... N <110.

-Residual Density- Solid scanning exposure is performed so that a 5 mm × 5 mm image is formed at a beam diameter of 4 μm, image exposure is performed using high-density energy light, and the transmission density of the image forming material on which an image is formed ( OD: measured transmission density-transmission density of the support itself)
With a densitometer [X-rite 310: manufactured by X-rite Co.]
TR] was evaluated on a 4-point scale using the visual density of 4 ... OD ≦ 0.060 3 ... 0.060 <OD ≦ 0.100 2 ... 0.100 <OD ≦ 0.250 1 ... 0.250 <OD.

-Occurrence of coating unevenness-The occurrence of coating unevenness was visually observed. A: No coating unevenness occurred B: Coating unevenness occurred on a part of wide area C: Application unevenness occurred on the entire wide area.

-Glossiness after solvent dilution-Using a glossmeter manufactured by Murakami Color Co., Ltd., the glossiness was expressed as a gloss value when the glossiness (92) of the standard plate was used.

[0125]

[Table 1]

From Table 1, it can be seen that the sample of the present invention has a high sensitivity and a sufficient density, has a high resolution, has no residual color, and has a purpose of increasing the wet film thickness in order to reduce coating unevenness of the image forming layer. It can be seen that the image forming material has good stability of the coating liquid even when diluted with a solvent in a large amount.

Claims (6)

[Claims] 1. An image forming layer comprising a ferromagnetic metal powder and a binder on a support, wherein the ferromagnetic metal powder has an average major axis length (L) of 30 ≦ L ≦ 120 (nm). And an image forming material having a saturation magnetization (σs) of 125 to 170 emu / g. 2. The image forming material according to claim 1, wherein said ferromagnetic metal powder contains 10 to 60 parts by weight of Co atoms per 100 parts by weight of Fe atoms. 3. The ferromagnetic metal powder comprises Fe as a constituent element,
Al, Co, and Sm, Nd, Y, Pr or L
2. The image forming material according to claim 1, comprising at least one rare earth element selected from a. 4. The method according to claim 1, wherein the binder is -SO ₃ M, -OSO ₃ M,
A resin having at least one type of polar group selected from —COOM and —PO (OM ₁ ) ₂ (where M represents a hydrogen atom or an alkali metal, and M ₁ represents a hydrogen atom, an alkali metal or an alkyl group). 2. The method according to claim 1, wherein
The image forming material as described in the above. 5. The binder according to claim 1, wherein the binder is composed of the polyurethane resin having the polar group and a vinyl chloride resin having the polar group or a polyester resin having the polar group. The image forming material as described in the above. 6. The image forming material according to claim 1, wherein the coating solution for the image forming layer is applied with a specific gravity at 20 ° C. in the range of 0.90 to 0.97. Manufacturing method.