JP2002230737A - Laminated body for thermal transfer and magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated body for thermal transfer having an easily releasable protective layer easily released from a release material (a supporting body for transfer) and having no trouble in adhesion properties to the other layer (e.g. a magnetic layer), in a laminated body for thermal transfer which is a constituent member of a magnetic card and the like and to provide a magnetic recording medium using the same. SOLUTION: Two or more cellulose derivative resins are used as constituent resins of the easily releasable protective layer of the laminated body for thermal transfer. At least two resins of them are essential component resins having hydroxyl group contents in regulated ranges (B: 2.5-3.5 mass%, C: 3.6 mass% or more) in the resins and the ratio of the two essential component resins and an other optional component resin in the protective layer resin is a regulated resin composition ratio (A/B/C=0-25/60-85/14-40 mass%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer laminate used as a component of a magnetic recording medium such as a magnetic card and a magnetic recording medium using the same. Here, in a broad sense, the magnetic recording medium is provided with a magnetic layer portion having a magnetic recording / reproducing function on a base made of metal, plastic, paper, or the like having various functions such as required outer shape and mechanical characteristics. It is a generic term for a group of products. For example,
Magnetic disks and tapes as computer hardware parts, magnetic cards such as plastic credit cards and cash cards, synthetic paper magnetic passbooks such as banks, and magnetic tickets such as paper tickets and pass tickets. is there. Along with this, in a narrow sense, only a magnetic layer portion having a magnetic recording / reproducing function or only ancillary portions necessary at least for securing the function, for example, in the above-described magnetic card, a magnetic tape used as a built-in component of the card (Also referred to as a magnetic stripe) may be directly referred to as a magnetic recording medium, and the “thermal transfer laminate” described below itself may be referred to as a magnetic recording medium.

[0002] The term "laminate for thermal transfer" refers to a magnetic recording / reproducing sheet (a tape formed by slitting or the like) having a magnetic layer and other functional layers laminated, which is mainly used as a component such as a magnetic card. In particular, the magnetic recording / reproducing sheet is prepared so that it can be loaded on a substrate of a magnetic recording medium by a processing method called “transfer”. The thermal transfer laminate is
Basically, the transfer support,
In the final product, a laminated structure composed of at least four layers of a protective layer as a role of protecting the functional layer from various kinds of contamination, a magnetic layer as a substantially functional layer for magnetic recording and reproduction, and an adhesive layer for thermal transfer is adopted. Also, the thermal transfer laminate is
Generally, one product (part) other than plastic sheet or synthetic paper, etc., which is the base of the magnetic recording medium
And used as a component raw material in the production process of magnetic card production in the inside or on the surface of the substrate of the magnetic recording medium.

[0003] The technique of the present invention relates to the above-mentioned protective layer, which is one of the constituent layers in the above-mentioned thermal transfer laminate. This protective layer is located between the transfer support and the magnetic layer, which is a substantially functional layer, and has special suitability for mutual adhesion between the upper and lower layers (interlayer adhesion). Required. There are two types of interlayer adhesion, [1]: interlayer adhesion at the interface between the transfer support and the protective layer (hereinafter, referred to as “support-layer / interlayer adhesion”), and [ 2]: interlayer adhesion at the interface between the protective layer and the magnetic layer, which is a substantially functional layer (hereinafter referred to as “coercivity-magnetic layer / interlayer adhesion”).
Of these, the latter [2] generally requires only a firm bond, whereas the former [1] is required to have "appropriate adhesive strength". And, the adhesiveness, which is “appropriate adhesive strength”, is a requirement of “easy peeling property, small peeling force” when expressed from the operation surface of peeling the transfer support. The present invention relates to a technique relating to difficulty in peelability. The present invention also relates to a technology of a magnetic recording medium using a laminate for thermal transfer having the above-mentioned releasable protective layer.

[0004]

2. Description of the Related Art The structure of such a protective layer (peelable protective layer) having both proper adhesiveness and good peelability at the same time in terms of adhesive strength between the support layer and the interlayer has been studied. And JP-A-7-65356 and JP-A-2000-293837. And there, in a synthetic resin composition comprising a binder resin, a wear resistance improver, a release agent, a cross-linking accelerator and the like, which is a conventional protective layer constitution, as a particularly suitable binder resin, the former is used. It has been proposed to use a resin composition composed of an acrylic resin / salt-vinyl acetate resin / isocyanate compound, and to use the cellulose derivative resin alone or in the latter case alone.

[0005] However, it has been difficult to obtain a releasable protective layer sufficient for practical use only with the configuration according to the above-mentioned disclosure. That is, in any of the former and the latter, the peeling strength is still too high, and during the peeling operation of the transfer support, it breaks and remains in the final product to make the product defective, and the peeling operation There was a problem of poor sex. In addition, the preparation of an acrylic resin composition and the selection of a cellulose derivative resin to prevent the occurrence of defects are difficult, and the addition of a release agent to ease the peel strength is another important property. In order to prevent a certain decrease in the coercive-magnetic-layer / interlayer adhesion, there is a drawback such as difficulty in adjusting the amount of addition.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a protective layer for a thermal transfer laminate, which is used in a peeling operation for peeling and removing an unnecessary transfer support from the protective layer.
Since the support-holding layer / interlayer adhesive strength is moderate, the peel strength value is small and easy to peel off, and other properties required for the protective layer are not impaired. Another object of the present invention is to provide a thermal transfer laminate having a peelable protective layer that is stable over time. Another object of the present invention is to provide a magnetic recording medium using the thermal transfer laminate having the easily peelable protective layer.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the resin constituting the protective layer for the purpose of improving the releasability of the thermal transfer laminate. And the composition ratio, etc.,
It is possible to obtain a thermal transfer laminate having a protective layer having a small peel strength and a desired easy peeling property. Further, by using the laminate to prepare a magnetic recording medium as a magnetic card, a protective layer can be obtained. The present invention has been completed by confirming that the evaluation of various other characteristics required for the present invention is at a practical level.

[0008] That is, the present invention is directed to a conventional structure in which one kind of cellulose derivative resin which is relatively hard, has good film properties, and is excellent in releasability is used alone as a binder resin for a protective layer. , A plurality of types of cellulose derivative resins,
Preferably, two types are used in combination. The reason why a plurality of types are used in combination is based on the reason that the degree of freedom in adjusting the peel strength is significantly improved as compared with the case where one type of the cellulose derivative resin is used alone. Usually, when the cellulose derivative resin is used as the resin for the protective layer,
In order to improve mechanical strength such as scratch resistance, hydroxyl group (-OH) which is a functional group present in cellulose derivative resin
Is used as a reaction point to add and crosslink an isocyanate compound. This crosslinking changes the properties of the resin, and accordingly, the peel strength. At this time, it is difficult to adjust the peel strength when one kind of resin is used alone, while it is easy to adjust the peel strength when two or more kinds are used. Here, a combination of a resin having a basic chemical structure different from that of the cellulose derivative resin, for example, an acrylic resin may be used, but it is not practical as a protective layer. The compatibility between the resins is often poor, which causes non-uniform peel strength, and as a result,
This is because this results in poor peelability. For this reason, it is necessary that all of the resins used in combination have a cellulose structure as a basic structure and a derivative resin in which a part thereof is substituted with an appropriate substituent. Here, the cellulose structure has a glucoside-linked glucose as a constituent unit.

Further, in the present invention, attention is paid to hydroxyl groups (-OH), which are functional groups of the cellulose derivative resin, and the cellulose derivative resin is classified according to the hydroxyl group content indicating the amount of hydroxyl groups in the resin, and the basis for the combined use. I do. Here, the hydroxyl group content is the ratio of the amount of hydroxyl group to the average molecular weight of the resin, and the unit is mass%. For example, if the resin having an average molecular weight of 30,000 has 50 hydroxyl groups,
Its hydroxyl group content is 2.8 [(50 × 17/30000) × 100] mass%. Then, the essential component resin and the optional component resin as the resin for forming the protective layer are determined according to the classification. The classification contents are the following three classifications of A, B and C resins. A resin: hydroxyl group content = 0 to 2.4% by mass (resin of optional component), B
Resin: hydroxyl group content = 2.5 to 3.5 mass% (first essential component resin), C resin: hydroxyl group content = 3.6 mass% or more (second essential component resin). The amount of hydroxyl groups in the cellulose derivative resin can also be represented by the number of hydroxyl groups bonded to a predetermined resin constituent unit. For example, when the cellulose constituent unit is glucose having a glucoside bond and four consecutive glucoses are another unit, the number of hydroxyl groups bonded thereto is the number of hydroxyl groups. A in the present invention,
The number of B and C resins bonded is a central value, one each,
2.3 and 4.

Further, in the present invention, the resin composition ratio in the protective layer is specified for the above-mentioned A, B and C resins. Here, the resin composition ratio is a ratio of each of the A, B, and C resins to the total amount of the cellulose derivative resin used for the protective layer, and the unit is represented by mass%. The specific composition ratio is as follows: the composition ratio Ar of the optional component resin A: 0 to 25% by mass, the composition ratio Br of the first essential component resin B: 60 to 85% by mass, and the second essential component resin C
Is Cr: 15 to 40% by mass. If the ratio is out of this range, the peel strength: the adhesive strength between the support and the support layer / interlayer becomes large, and the desired easy peelability cannot be obtained. In addition, it becomes impossible to satisfy various characteristics required for the protective layer.
In other words, the peel strength becomes 100 mN or more, and
Exceeds the target value of “10 to 80 mN”, and cannot be evaluated as easily peelable. In addition, the mechanical properties such as the coercive layer / adhesive strength, heat resistance, chemical resistance, and abrasion resistance are reduced, which causes a problem as a protective layer. These behaviors are as described in Examples and test results in Table 1 described later.

In the present invention, in addition to the above-described inventions of the thermal transfer laminate and the protective layer, the present invention uses the thermal transfer laminate and employs and uses well-known transfer techniques and materials. A recording medium can be manufactured.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The laminate for thermal transfer according to the present invention is obtained by applying a coating prepared for forming each of a peelable protective layer, a magnetic layer and an adhesive layer in this order on a transfer support. , Dried and manufactured. Further, the magnetic recording medium: magnetic card of the present invention is manufactured by bringing the adhesive layer side of the thermal transfer laminate into close contact with the surface of the magnetic recording medium substrate, fusing and transferring, and then peeling off the transfer support.

As a substance involved in the improvement of the releasability of the protective layer for thermal transfer, which is the object of the present invention, there is a transfer support material. This transfer support material is generally a synthetic resin film or synthetic paper called release paper, and can be selected without any particular limitation as long as it meets the conditions of use. In the present invention, a synthetic resin film is suitable, and among them, the thickness is preferably 3 to 100 in terms of heat resistance and tensile strength.
A μm PET (polyethylene terephthalate) film is more preferred. This is used in the embodiment of the present invention.

As the binder resin used in the coating material for forming the peelable protective layer, known and commonly used binder resins can be used. And those excellent in the releasability from the PET film are preferable. Examples of such resins include cellulose derivative resins, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate nitrate, and cellulose acetate propionate.

Cellulose used in the peelable protective layer of the present invention
Derivative resin has a weight average molecular weight of 10,000 to 700
No. 00 cellulose derivative resin. Here, if the molecular weight is too small, properties such as easy peelability and peeling stability with time will not be exhibited, while if it is too large, the viscosity of the coating material will be high and thin film coating will be difficult.

Cellulose used for the peelable protective layer of the present invention.
Since the high / low hydroxyl group content in the resin derivative resin has the following adverse effects, the hydroxyl group content in actual use is in the range of 1 to 7%. That is, when the hydroxyl group content is low, heat resistance and mechanical strength characteristics (scratch resistance) are inferior, causing burn-in during hot pressing and breakage of the protective layer during running of the recording head. Conversely, if the hydroxyl group content is high, it becomes difficult to make a paint because it is hardly soluble in organic solvents,
The paint thickens due to the addition of the crosslinking accelerator, making application difficult.

Cellulose used in the peelable protective layer of the present invention
A, B classified by hydroxyl group content
Typical examples of each of the resins C and C are as follows, and their outlines—trade names, chemical names, hydroxyl group content, and molecular weights—are described. These are also used in Examples described later. A resin: CAB381-0.1, cellulose acetate phthalate, 1.3% by mass, 20,000 B resin: L-AC L-20, cellulose acetate, 3.0% by mass, 33,000 C resin: CAP504-0.2, cellulose acetate phloiodate, 5.2% %, 15,000

When it is unavoidable to use a resin having a basic chemical structure different from that of the above-mentioned cellulose derivative resin, an appropriate resin is selected within a range in which there is no problem in compatibility.
Can be added and used. Examples of such a resin include polyvinyl chloride, acrylic resin, epoxy resin, polycarbonate, and the like. The amount of the resin used is 0 to 1 corresponding to the optional component resin A in the resin composition ratio described above. 25% by mass.

When the above-mentioned cellulose derivative resin is used as the resin for the releasable protective layer, an isocyanate compound as a crosslinking accelerator is usually added to improve the mechanical properties of the protective layer, for example, abrasion resistance. Then, a crosslinking reaction is caused to accelerate the curing. The use amount of this isocyanate compound is preferably 2 to 30 parts by mass based on 100 parts by mass of the binder resin.

Further, the release protective layer may contain a known and commonly used release agent in order to improve the release property between the transfer support and the protective layer. Examples of the release agent include a fluorine resin, a polyolefin wax, a natural wax, and a silicone release agent.

The preparation of the paint for forming the peelable protective layer is performed by adding the above-mentioned cellulose derivative resin, a releasing agent and other additives to a mixed solvent such as acetone, ethyl acetate, butyl acetate, toluene and cyclohexanone. 40% by mass
Dissolve and suspend to a concentration of 1.

The peelable protective layer is formed by coating the above coating composition on a transfer support (PET film) with a dry coating thickness of 0.4 to 0.4%.
The coating is performed so as to have a thickness of 2.5 μm, dried in a nitrogen atmosphere, and then heat-cured in air at 100 to 120 ° C. for 10 seconds to 5 minutes. There are no particular restrictions on the application method,
Known and commonly used systems can be used. It can be manufactured by adopting a coating material manufacturing system having a single layer or a plurality of layers. Specifically, for example, gravure method, reverse method, air doctor coater method, blade coater method, air knife coater method, squeeze coater method, impregnation coater method, transfer roll coater method, kiss coater method, cast coater method, spray coater method, die System and the like.

As the binder resin used in the coating material for forming the magnetic layer, known and commonly used, for example, a polyvinyl chloride resin, an acrylic resin, an acrylic urethane resin, a nitrocellulose resin, a polyurethane, a polyester, etc., alone or in combination. And can be used.

As the magnetic material used for the coating material for forming the magnetic layer, known and commonly used, for example, γ-iron oxide, magnetite, cobalt-coated iron oxide, chromium oxide, iron-based metal magnetic powder, strontium ferrite, barium Magnetic powder such as ferrite can be used.

The preparation of the coating material for forming a magnetic layer is carried out by preparing the above-mentioned magnetic powder and 20 to 30% by mass of the above-mentioned binder resin, and if necessary, a known and commonly used dispersion stabilizer, surfactant and resin. A filler or the like is dissolved and dispersed in a mixed solvent such as methyl ethyl ketone, toluene, and cyclohexanone. The solid content concentration of the paint at that time is 25 to 50 mass%
It is preferred that For dissolution and dispersion, a known and commonly used disperser such as a ball mill and a sand grind mill can be used.

The magnetic layer is formed by adding an isocyanate compound as a curing agent to the above-mentioned coating material for forming a magnetic layer, and coating the above-mentioned releasable protective layer so that the dry coating film thickness becomes 2 to 20 μm. After drying in nitrogen atmosphere, in air
Heat cure at 100-120 ° C for 10 seconds-5 minutes. The coating method is not particularly limited, and a known and commonly used method can be used. It can be manufactured according to the method used for manufacturing a single-layer or multi-layer coating product. Specifically, for example, gravure method, reverse method, air doctor coater method, blade coater method, air knife coater method,
Examples include a squeeze coater method, an impregnation coater method, a transfer roll coater method, a kiss coater method, a cast coater method, a spray coater method, and a die method.

The binder resin for the adhesive layer may be a thermoplastic binder resin which is tack-free at room temperature but develops adhesive properties when heated, and may be a known and commonly used, for example, polyvinyl chloride resin. Resin, polyurethane resin, or the like can be used.

The preparation of the coating for forming the adhesive layer is carried out by adding methyl ethyl ketone, so that the content of the binder resin is 3 to 70% by weight.
It is prepared by dissolving in a mixed solvent such as toluene. At this time, silica, polyethylene wax or the like can be added as an anti-blocking agent in a high temperature environment.

The adhesive layer is formed by applying the above-mentioned paint for forming an adhesive layer on the magnetic layer so that the thickness of the dried coating film becomes 0.3 to 10 μm, and drying in air at 50 to 120 ° C. The coating method is not particularly limited, and a known and commonly used method can be used. It can be manufactured according to the method used for manufacturing a single-layer or multi-layer coating product. Specifically, for example, gravure method, reverse method, air doctor coater method, blade coater method, air knife coater method, squeeze coater method, impregnation coater method, transfer roll coater method, kiss coater method, cast coater method, spray coater method, die System and the like.

The magnetic recording medium of the present invention: As described above, the magnetic card is obtained by thermally transferring the above-mentioned thermal transfer laminate to the surface of the magnetic recording medium substrate. The substrate is usually a laminate, and is composed of a core material capable of being printed or the like called a core sheet and a cover sheet called an overlay sheet provided above and below the core material.

[0031]

The present invention will be described below in more detail with reference to specific examples and comparative examples. However, the present invention is not limited to these examples. In addition, below, a part shall represent a mass part.

Example 1 <Composition of Paint for Forming Removable Protective Layer> Cellulose acetate: B resin 7.5 parts (“L-AC L-20” manufactured by Daicel Chemical Industries, Ltd.) Cellulose acetate propionate: C resin 1.8 parts (“CAP504-0.2” manufactured by Eastman Chemical Company) Polyethylene wax 2.0 parts (“High Wax 200PF” manufactured by Mitsui Petrochemical Co., Ltd.) Soybean lecithin 0.1 part Acetone 24.3 parts Acetic acid Ethyl 24.3 parts Cyclohexanone 19 parts Toluene 19 parts Isocyanate compound 2 parts ("Barnock D-750" manufactured by Dainippon Ink and Chemicals, Inc.)

<Composition of magnetic layer forming paint> Ba ferrite magnetic powder 40 parts (Toda Kogyo Co., Ltd. "MC-127") Vinyl chloride resin 6 parts (Zeon Corporation "MR-110") Polyurethane resin 4 parts (“T-5206” manufactured by Dainippon Ink and Chemicals, Inc.) 20 parts of methyl ethyl ketone 20 parts of toluene 8 parts of cyclohexanone 2 parts of isocyanate compound (“Barnock D-750” manufactured by Dainippon Ink and Chemicals, Inc.)

<Composition of Coating Material for Forming Adhesive Layer> Vinyl chloride-vinyl propionate copolymer resin 10 parts (Ryulon QC640 manufactured by Tosoh Corporation) Methyl ethyl ketone 45 parts Toluene 45 parts

<Preparation of Laminate for Thermal Transfer> A coating for forming a peelable protective layer was formed on a transfer support (PET film) using a reverse coating system coating machine so that the dry coating thickness became 1.0 μm. And dried in a nitrogen atmosphere.
The composition was thermally cured at 5 ± 5 ° C. for 30 seconds to form a peelable protective layer. On the releasable protective layer, the dry coating thickness is 14 μm.
m, a coating material for forming a magnetic layer is applied by a reverse coating method coating machine and dried in a nitrogen atmosphere.
The magnetic layer was formed by heat curing for 30 seconds. Further, on the magnetic layer, a coating for forming an adhesive layer is applied by a reverse coating method coating machine so that a dry coating thickness becomes 1.5 μm,
Drying was performed in a nitrogen atmosphere to form an adhesive layer. This laminate is the laminate for thermal transfer of the present invention.

<Magnetic Recording Medium: Preparation of Magnetic Card Substrate Material and Substrate> “Vinifoil C-8195” manufactured by Mitsubishi Plastics, Inc. (for a transparent overlay sheet, 100 μm thickness) “Vinifoil C- manufactured by Mitsubishi Plastics, Inc. 4636N "(for a white core sheet, 280 μm in thickness) The above-mentioned materials were sequentially laminated, and a substrate was obtained by a usual method of hot pressing at 120 ° C.

<Preparation of Magnetic Recording Medium: Magnetic Card> The thermal transfer laminate was transferred to the substrate obtained above by a conventional method to obtain a magnetic recording medium: magnetic card. The apparatus actually used is a simple card making machine "Desktop Laminator OLA6" manufactured by Oasis. The laminating temperature is 80 ° C,
After performing a temporary transfer under the condition of the pressure memory 45 for a fixed time of 120 seconds and removing the PET film as the transfer support,
Again, temperature 160 ° C, fixed time 120 seconds, pressure memory 6
This was performed by performing the main press in step 5.

Comparative Example 1 A thermal transfer laminate and a magnetic recording medium were produced in the same manner as in Example 1 except that the composition of the coating material for forming a peelable protective layer was as follows.

Cellulose acetate: 9.3 parts of B resin (“L-ACL-20” manufactured by Daicel Chemical Industries) Polyethylene wax 2.0 parts (“High Wax 200PF” manufactured by Mitsui Petrochemical Co., Ltd.) Soybean lecithin 1 part Acetone 24.3 parts Ethyl acetate 24.3 parts Cyclohexanone 19 parts Toluene 19 parts Isocyanate compound 2 parts ("Vanock D-750" manufactured by Dainippon Ink and Chemicals, Inc.)

Comparative Example 2 A laminate for thermal transfer and a magnetic recording medium were produced in the same manner as in Example 1, except that the composition of the coating material for forming the peelable protective layer was as follows.

Cellulose acetate propionate: 9.3 parts of C resin (“CAP504-0.2” manufactured by Eastman Chemical Company) 2.0 parts of polyethylene wax (“High Wax 200PF” manufactured by Mitsui Petrochemical Co., Ltd.) Soybean Lecithin 0.1 part Acetone 24.3 parts Ethyl acetate 24.3 parts Cyclohexanone 19 parts Toluene 19 parts Isocyanate compound 2 parts ("Vanock D-750" manufactured by Dainippon Ink and Chemicals, Inc.)

Comparative Example 3 A thermal transfer laminate and a magnetic recording medium were produced in the same manner as in Example 1, except that the composition of the coating material for forming a peelable protective layer was as follows.

Cellulose acetate: 7.5 parts of B resin (“L-ACL-20” manufactured by Daicel Chemical Industries) Cellulose acetate butyrate: 1.8 parts of A resin (“CAB381-0.1” manufactured by Eastman Chemical Company) Polyethylene wax 2.0 parts (“High Wax 200PF” manufactured by Mitsui Petrochemical Co., Ltd.) Soybean lecithin 0.1 part Acetone 24.3 parts Ethyl acetate 24.3 parts Cyclohexanone 19 parts Toluene 19 parts Isocyanate compound 2 parts (Large) "Barnock D-750" manufactured by Nippon Ink Chemical Industry Co., Ltd.)

Comparative Example 4 A thermal transfer laminate and a magnetic recording medium were produced in the same manner as in Example 1, except that the composition of the coating material for forming a peelable protective layer was as follows.

Cellulose acetate: 4.7 parts of B resin (“L-ACL-20” manufactured by Daicel Chemical Industries) Cellulose acetate propionate: 4.6 parts of C resin (“CAP504-0.2 manufactured by Eastman Chemical Company”) )) Polyethylene wax 2.0 parts (Mitsui Petrochemical Co., Ltd. "High Wax 200PF") Soybean lecithin 0.1 part Acetone 24.3 parts Ethyl acetate 24.3 parts Cyclohexanone 19 parts Toluene 19 parts Isocyanate compound 2 parts ( "Barnock D-750" manufactured by Dainippon Ink and Chemicals, Inc.)

(Test Items and Test Results) <I. Peelability test (peel strength: support-layer / layer adhesion)
> Removability between transfer support (PET film) and releasable protective layer, that is, peel strength: Measure adhesive strength between support-support layer and interlayer. From this value, it is determined how easy the peelability is. If the peel strength value is in the range of 10 to 80 mN, it is determined that the peelability is easy.
The laminated body for thermal transfer is cut into a width of 10 mm to produce a laminated body for thermal transfer in a tape form. This tape-shaped laminate for thermal transfer was thermally transferred to an overlay sheet to obtain a peel test sample. The thermal transfer device and thermal transfer conditions are as follows. Apparatus: heat sealer (manufactured by Tester Sangyo Co., Ltd.), condition: hot press at 120 ° C., 9.9 seconds, 0.4 MPa. Next, the peel test sample obtained here is put on a peel test machine,
The force for peeling off the PET film as the transfer support from the protective layer, that is, the peel strength was measured. The peeling tester used was a high-speed peeling tester (manufactured by Tester Sangyo Co., Ltd.).

<II. Adhesion test (coercivity / magnetic layer / interlayer adhesion)> Tests the adhesion between the releasable protective layer and the magnetic layer (coercivity / magnetic layer / interlayer adhesion) to determine whether or not there is predetermined adhesion. . The magnetic recording media prepared in the above Examples and Comparative Examples were evaluated according to the grid tape method described in JIS K 5400-1990, and the quality of the adhesiveness was determined.

<III. Heat Resistance Test> The magnetic recording media prepared in the above Examples and Comparative Examples were tested by hot pressing with a flat pressure press (Toyo Seiki Co., Ltd.). That is,
The magnetic recording medium is sandwiched between stainless steel plates, and hot-pressed (flat pressure press: manufactured by Toyo Seiki Co., Ltd.) at a temperature of 180 ° C., a pressure of 8 MPa, and a heating time of 30 minutes. Then, the stainless steel plate was removed, and the stainless steel plate on the side that was in contact with the magnetic tape (other stainless steel plates were in contact only with the overlay sheet)
Of the magnetic layer is checked to confirm the state of sticking of the magnetic layer to the stainless steel plate. The stainless steel plate was confirmed, and it was visually confirmed whether or not the magnetic layer of the magnetic recording medium was transferred to the stainless steel plate, and the quality of the heat resistance was determined.

<IV. Chemical Resistance Test> The magnetic recording media prepared in the above Examples and Comparative Examples were tested by dissolving and scraping the protective layer with a chemical. Test chemicals include methyl ethyl ketone (MEK), toluene,
Use each organic solvent of alcohol. With the room temperature and the solvent temperature set at 25 ± 5 ° C., the same portion on the surface of the protective layer of the magnetic recording medium is rubbed with a cotton swab soaked in the test solvent. After every 10 rubs, the rubbing surface of the cotton swab is visually observed to evaluate whether the magnetic layer of the magnetic recording medium adheres to the cotton swab and is colored from brown to black. The degree of solvent resistance was judged by comparing the number of times of rubbing when coloring was recognized.

<V. Scratch resistance (mechanical strength) test> The magnetic recording media prepared in the above Examples and Comparative Examples were punched into a magnetic card shape, and information was written with a card writer. Then, the state of the decrease in the output of the read information and the state of the surface scraping of the magnetic tape portion on the magnetic card were visually observed, and the quality of the abrasion resistance (mechanical strength) was determined.

<Test Results> The test results of the above five items I to V are shown in Table 1 below.

[0052]

[Table 1] Table 1. Test results of peelable protective layer in Examples (Note) In the table, indicates the type of chemicals: methyl ethyl ketone, toluene, and ethanol.
Symbols (○, ×) indicate good (○) and bad (×) of the evaluation result.

(Summary of Evaluation Results) From the results shown in Table 1, only Example 1 (two types of cellulose derivative resins B and C were used in combination and in compliance with the specified amount) exhibited the desired easy peeling property (20 mN). Other properties required for peelable protective layer [II-V]
Was also satisfied. Further, in Comparative Examples 1 and 2 in which one kind of each of B and C resins was used alone, Although peelability is at a considerable level, II. Adhesiveness or V. This was a problematic evaluation result in terms of scratch resistance, and the objective was not achieved. Comparative Example 3 using two types of resins together
(Combination of A and B) and Comparative Example 4 (combination of B and C), II. Although the adhesiveness is good, the desired I.V. The peelability was large and inadequate, and the other properties [III to V] were not satisfactory, and the purpose was similarly not achieved. Furthermore, from Comparative Examples 3 and 4, it was found that C resin was an essential component resin and that the resin composition ratio had a specified amount (lower limit amount of B resin). In addition, the presence or absence of a temporal change was also evaluated. As a result of performing the same test as described above one month later, no significant difference was found in the test results. In particular, in Example 1, it was confirmed that the releasability and other characteristics were good, and that the stability over time was high.

[0054]

The laminate for thermal transfer of the present invention and the magnetic recording medium using the same are unnecessary in the peeling operation step in the final product manufacturing process, so that the transfer support that needs to be removed is protected for releasability. When peeled from the layer, it is easily peelable. For this reason, the transfer support (PET film) is not broken or remains in the protective layer due to poor peeling, so that defective products and process troubles can be prevented. This has a remarkable effect on stabilizing the manufacturing process and product quality of the magnetic recording medium, reducing the cost of the product, saving resources or reducing waste.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a laminate for thermal transfer according to the present invention.

FIG. 2 is a longitudinal sectional view of the magnetic recording medium of the present invention after a thermal transfer laminate is transferred onto a magnetic recording medium substrate, and an uppermost transfer support is peeled off and removed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer support 2 Peelable protective layer 3 Magnetic layer 4 Adhesive layer 5 Magnetic recording medium base

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Miyahara Teshu 4-12-8 Midorioka, Ageo-shi, Saitama 206 No. 206 Tomiyoshi Corp. F-term (reference) 5D006 AA01 DA01 FA00

Claims (4)

[Claims] 1. A thermal transfer laminate in which at least a releasable protective layer, a magnetic layer and an adhesive layer are laminated in this order on a transfer support, the binder resin of the releasable protective layer has a different chemical structure. A laminate for thermal transfer, comprising a combination of two or more types of cellulose derivative resins. 2. Among two or more types of cellulose derivative resins used in combination with the releasable protective layer, at least two types are essential component resins for defining a hydroxyl group content, and one of the two types is 2.5 to 3.5 mass%. %, The other one is 3.6% by mass
The thermal transfer laminate according to claim 1, wherein the laminate is a cellulose derivative resin having the above hydroxyl group content. 3. In two or more cellulose derivative resins having different hydroxyl group contents used in combination with the peelable protective layer, the resin composition ratio of the two or more binder resins is the resin ratio in the peelable protective layer. In the optional component resin hydroxyl group content is
The ratio of the resin of 0 to 2.4% by mass is 0 to 25% by mass, and the ratio of the resin having a hydroxyl group content of 2.5 to 3.5% by mass as the first essential component resin is 60 to 85% by mass and the second essential component resin. 3. The thermal transfer laminate according to claim 1, wherein the proportion of the resin having a hydroxyl group content of 3.6% by mass or more is 15 to 40% by mass. 4. A magnetic recording medium using the thermal transfer laminate according to claim 1 as a magnetic recording / reproducing layer.