JPS5927717B2 - pressure sensitive transfer material - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel pressure sensitive transfer material.

More specifically, a stretched asymmetrically oriented polyethylene terephthalate film (plastic film A) having a high tensile strength and a low elongation; A pressure-sensitive transfer material using a laminate of a plastic film B selected from the group consisting of a nylon film having a polyethylene terephthalate, a non-stretched and uniformly oriented polyethylene terephthalate film, a polyethylene film, and a polypropylene film as a plastic film base material. . In areas such as carbon paper and typewriter ribbon, plastic film substrates have been recognized to have many advantages over paper substrates in terms of versatility of use.

Plastic film substrates are used where complete releasability of the transfer layer is required, such as one-time typewriter ribbons for producing good quality copies. This is because the plastic film substrate allows complete removal of the transfer layer. U.S. Patent No. 30618
No. 86 is an example of such a ribbon. Also,
Plastic film substrates are also used in cases where repeatability is of paramount importance and complete removability of the transfer layer is not required. In other words, plastic film substrates do not absorb oil from the so-called ink-permeating porous resin ink layer, so carbon paper or ribbons made with such plastic film substrates may dry out over time, or the image may deteriorate. This is because they do not lose their ability to form. For example, U.S. Patent No. 30378
The specification of No. 79 gives an example of such a transfer material. The greatest challenge facing the prior art is the requirement that plastic film substrates coexist with properties that are inconsistent with the inherent properties of the film.

The most popular plastic film is an unstretched, uniformly oriented polyethylene terephthalate film commercially available under the registered trademark Mylar A. This film has a thickness of about 25.4 μ (1 mil) and a pressure of about 17.6 Kf/〒 (25,000 psi).
It has a tensile strength of , is very tough and tear resistant. Mylar-A has an elongation (MD) of about 120%, so when type pressure is applied, the deformability around the type pressure surface is not so large, but it still causes embossment during type printing. Since the embossment remains intact, when using typewriter ribbon, it is difficult to rewind it onto a spool of limited capacity. Other films such as polyethylene film, polypropylene film and nylon film have substantially higher elongation than Mylar-A;
Create an emboss larger than that. Additionally, these films have substantially lower tensile strength than Mylar-A and suffer from the disadvantage that they tear or break more easily during handling or use than Mylar-A. Polyethylene film is also used as a base material for pressure-sensitive transfer materials, which tends to reduce embossing that occurs during type printing.
It is also known to use other types of films, such as J-rate films. Such films are available under the registered trademark Mylar T and have an elongation (MD) of approximately 40% for a 1 mil thick film, relative to Empos. Has very high resistance. Mylar-T is also about 31.6 Kf/M
It has an extremely high tensile strength (MD) of J (45,000 ps1). However, because Mylar-T is extremely strong and exhibits great resistance to elongation and distortion around the type pressure surface, Mylar-T is brittle and often shatters or cracks under type pressure. This may cause damage to the typewriter ribbon. Another significant shortcoming in conventional plastic film ribbon technology is that the plastic film ribbon stretches and thins due to the tension it experiences during winding, thereby causing the ribbon to be wound very tightly onto the ribbon spool. It means that it will be taken. This often causes the surface of the ink layer to adhere to the uncoated back surface of the overlapping plastic film substrate, or the ink liquid in the ink layer to bleed onto the back surface. Therefore, when the ribbon is unwound, the ink layer is partially peeled off or transferred to the back side of the base film, and the function of that part as a transfer material is lost. Similar problems frequently occur due to the lack of dimensional stability of plastic film substrates with changes in temperature.

Thus, the ribbon is typically wound onto a spool under temperature conditions near room temperature. If the wound ribbon encounters abnormal temperature changes, such as those that may occur during storage or shipping, the expansion or contraction of the plastic film substrate may cause damage between the overwound ribbon and the ribbon. Unusual pressure will occur. Similar to the tension discussed above, this can cause the ink layer to adhere to or bleed onto the uncoated backside of the plastic film substrate, and also cause the ink to bleed onto the uncoated backside of the plastic film substrate, and also cause This can cause the fabric to become stiff, loose, or wrinkled. Such dimensional changes make handling of the wound ribbon difficult and adversely affect the quality of the images transferred by the ribbon. The present invention uses a plastic film base material that is extremely tough and has excellent breakage resistance, and also has the required deformability around the type pressure surface when type pressure is applied, and also has embossment retention resistance. The present invention provides a pressure-sensitive transfer sheet and a pressure-sensitive transfer phone. The present invention also provides pressure-sensitive transfer sheets and pressure-sensitive transfer ribbons that have excellent dimensional stability against tension, temperature changes and repeated use, and excellent transfer image forming properties.

The objects and advantages of the present invention are that an ideal plastic film substrate having rare toughness, deformability, embossing resistance and dimensional stability is obtained by combining two thin plastic films A and B as described below. This was achieved by the discovery that it could be produced by laminating.

Plastic film A is a stretched and asymmetrically oriented polyethylene terephthalate film having high tensile strength and low elongation, and is relatively brittle in normal state but has embossing residue resistance, and the other plastic film B is a polyethylene film. , a polypropylene film, an unstretched, uniformly oriented polyethylene terephthalate film, and a nylon film, which have relatively low tensile strength, high elongation, and emboss retention. Here, "stretched and asymmetrically oriented" means, for example, that the stretching or elongation in one of the machine direction (MD) and the direction perpendicular to the machine direction (TD) is greater than the elongation in the other direction. This means that the plastic film has been asymmetrically stretched in only one direction or both directions, and "uniformly oriented without stretching" means that it has been stretched equally in the MD and TD directions. By the combination of
A laminate is obtained that has the unique characteristics of each plastic film. It can be expected that the relatively soft plastic film B, which has deformability and high elongation, will be strengthened by being laminated with a tougher and less deformable polyethylene terephthalate film. However, the laminate is stronger than the polyethylene terephthalate film itself,
The brittleness disappears, and the fracture, cracking, and breakage (Frae
turing) and breakage, and the laminate has a greater deformation per caliper than the polyethylene terephthalate film itself and is softer than the plastic film B.
It would not be expected to have greater embossing retention resistance than itself.

Further, the laminate of the two plastic films A and B has greater dimensional stability against changes in tension and temperature than the soft plastic film B itself. This means that when two films A and B have different coefficients of expansion and one film tends to be affected by heat or tension, the other film remains stable and the stable film This is due to the fact that the dimensional change of the other film is suppressed. The plastic film substrates of the present invention each have a maximum caliper of approximately 25.4μ (1
It consists of a laminate obtained by laminating the plastic films A and B with a mill.

Preferably, one of the plastic films B is thinner than the other and has a maximum caliper of about 12.7 microns (0.5 mil). The minimum thickness of each of plastic films A and B is determined in most cases by commercial availability, but is typically on the order of about 0.51 microns (0.2 mils). A tough plastic film, such as that available from DuPont under the registered trademark Mylar-T, is
approximately 25.4μ (1 mil) and approximately 23.4μ (0.92μ)
The ultimate tensile strength (MD) in each case is approximately 3
1.6K9/MJ (45,000psi) and approx.
．． 5K-f/m! t (32,000 psi) and its elongation (MD) is 40% and 37%, respectively.

However, the tensile strength (MD) at a thickness of about 25.4 μ (1 mil) is about 21.8 Kf/M7jC about 31,
000 pSi) or more, and the elongation (MD) is about 60
Other similar stretched, asymmetrically oriented polyethylene terephthalate films of 96 or less are also suitable. A preferred soft plastic film B is manufactured by DuPont Canada (D) under the registered trademark Dartek.
It is a nylon film available from uDOntCanada.

This film has a tensile strength of approximately 8.7K9/m (12,
400 psi) and the elongation is approximately 400%. Another suitable soft plastic film B is available as Mylar-A and has a tensile strength (MD) of about 1.
An unstretched and uniformly oriented polyethylene terephthalate film with 7.6 Kf/77 ZJ (25,000 psi) and 120% elongation (MD) or tensile strength (M
D) Oriented polypropylene film of about 12.0 Kf/IIJ (17,000 psi) and elongation (MD) of about 160% or tensile strength (MD) of about 5.0 K9/M
d (7,100 psi) and elongation (MD) approximately 360 (
fl) high-density polyethylene film, etc. In all cases, the soft plastic film B has a tensile strength (MD) of less than about 18.3 Kf/mΔ (26,000 psi) and an elongation (MD) of greater than about 100%. The test method adopted for measuring tensile strength and elongation was ASTM D-882-73 (force method A), and a test film with a thickness of approximately 25.4 μm (1 mm) was measured. Film A is a stretched and asymmetrically oriented polyethylene terephthalate film, which is formed by extruding an amorphous polyethylene terephthalate film, cooling it, and stretching it in one direction to a higher degree than in the other. It is produced by heating the stretched film above its glass transition point in order to keep it fixed without shrinking.

More specifically, an amorphous polyethylene terephthalate film is first extruded at a temperature of about 275 to 310°C, cooled to about 60 to 80°C, and then heated to 80 to 90°C to extrude in one direction. For example, it is stretched in the transverse direction (TD) to 3.4 to 3.7 times the width of the original fabric. Furthermore, the obtained uniaxially stretched film was heated to a temperature of 119 to 150°C.
heated to a higher degree in another direction, e.g. machine direction (MD) or extrusion direction, i.e.
Stretched 3 to 5 times. The resulting biaxially stretched film is then heat-treated at a temperature higher than that in the second stretching step, i.e., 160-230°C, during which time the film is heated in a tenter-like device to prevent shrinkage. something held under tension. The heat-treated film is finally cooled to room temperature, still under tension, and then removed. This asymmetrically oriented and heat treated polyethylene terephthalate film has substantially improved resistance to stretching and embossing residue when type pressure is applied, compared to conventional, evenly oriented polyethylene terephthalate film. It has been improved.

"Embossing retention" refers to the property of a film in that it is distorted by impact pressure and does not return to a substantially flat and smooth state when the impact pressure is removed. The two plastic films A and B as described above are laminated by conventional methods, preferably with a thin adhesive intermediate layer therebetween to firmly bond the two films. When a tacky interlayer is provided, a non-tacky heat-activated adhesive may be applied to one of the films upon cooling to facilitate stacking of the films prior to lamination. The two plastic films A and B are pressed into intimate contact and the adhesive is then activated by heating to bond the two films together.

Canadian Patent No. 578286 and No. 7121
No. 35 teaches compositions and methods for adhesively bonding two films together. If the adhesive interlayer is applied using a volatile solvent, care must be taken to prevent the solvent from getting mixed in between the films and creating air bubbles. The adhesive intermediate layer can also be formed by applying without a solvent a liquid resin that reacts and solidifies by curing, such as an epoxy resin, a liquid acrylic monomer, or a blended polymer. Another advantage of the plastic film substrate of the present invention is that it allows the transfer layer to be provided with a film surface having different adhesive properties. The wax-based hot melt type transfer layer is oleophilic and has excellent receptivity to polyolefin films, but relatively poor receptivity to Mylar-T. Transfer layers formed by solvent coating using water have relatively poor receptivity to polyolefin films;
It has excellent receptivity to Mylar-T. Similarly, the two plastic films A and B have substantially different dissolution properties. Therefore, in order not to impair the toughness of the plastic film base material, the other plastic film and the transfer layer are solvent bonded (SO) using a volatile solvent that does not attack either plastic film.
It is preferable to do so. In the present invention, there are no particular limitations on the transfer layer provided on the plastic film base material, and for example, a so-called ink-oozing type transfer layer made of a porous structure of a synthetic thermoplastic resin containing an image-forming substance in its pores. (See Example 1 below)
Alternatively, an oleophilic wax transfer layer containing an image-forming substance and having an affinity for the plastic film substrate (see Example 2 below) can be suitably employed.
The pressure-sensitive transfer material of the present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A stretched and asymmetrically oriented polyethylene terephthalate film of about 23.4μ (0.92 mm) and a polyethylene terephthalate film of about 12.
7 μ (0.5 mil) nylon film, about 2.5
A plastic film substrate was prepared by laminating through an adhesive interlayer of 0.1 mil polyester resin and having a 1.6 mil caliper.

Next, the surface of the polyethylene terephthalate film of this film base material is coated with a volatile solvent of about 5.1μ (0.5μ).
2 mm thin polypyrolidene chloride resin (Saran)
An ink bonding layer of ran) was applied.

After removing the solvent, a composition as shown in Table 1 is coated on the surface of the ink bonding layer, and the solvent is evaporated to form a layer with a thickness of about 1.
A 5.2 micron (0.6 mil) solid transfer layer was formed. The ethyl acetate solvent softens the ink bonding layer before evaporating, allowing a tight bond with the transfer layer. The resulting web is wound into a roll and then cut into sheets or ribbons to produce a reusable, ink-leaching pressure-sensitive transfer material that can form extremely clear and sharp reproduced images under imaging pressure. did.

Example 2 First, Mylar T (stretched and asymmetrically oriented polyethylene terephthalate film) having a thickness of about 12.7μ (0.5 mil) was coated with polyurethane resin (DaltOsec) dissolved in a volatile solvent. A thin continuous film is applied and the solvent is evaporated to a thickness of about 2.
A 54 μm (0.1 min) adhesive intermediate layer was formed.

Then, the surface of the adhesive intermediate layer of Mylar-T was coated to a thickness of about 12.7 cm.
μ (0.5 mil) polypropylene film and press them tightly together through the nip of heated rollers to crosslink or cure the polyurethane resin at about 150°C to form Mylar-T and polypropylene film. A single plastic film substrate having a caliper of 25.4μ (1 mil) or larger was created by combining the two. The surface of the polypropylene film of the obtained plastic film base material was hot melt coated with a hot melt type composition as shown in Table 2. The thus obtained web is cut into sheets or ribbons, which have toughness, deformability, and dimensional stability, and can be used for one-time use to form clear transferred images when image forming pressure is applied. It is a pressure sensitive transfer material.

The typewriter ribbon produced according to the above embodiments has a much higher dimensional stability than the so-called soft plastic film B alone under temperature changes and tension changes due to repeated typing operations. ,
It also has greater resistance to crushing, cracking and/or breakage than stretched, asymmetrically oriented polyethylene terephthalate film (Blastic Film A) alone.

Such tie lighter ribbons are wound onto spools under varying degrees of small tension, subjected to temperature changes and repeated tie operations, and checked periodically. Any variation in the tightness or looseness of the wrapping of the ribbon on the subur, and any increase in bulk due to the number of turns of the ribbon, is within acceptable limits. The carbon sheet manufactured according to the example has dimensional stability, fracture resistance, and cracking resistance comparable to that of a carbon sheet using a single plastic film base material made of either plastic film A or B described above. It has excellent durability and embossing residue resistance.

The above values are specific for a plastic film substrate of a specific thickness of 1.0 mil (25.4 microns), and
The stretched or unstretched polyethylene terephthalate film, nylon film, polyethylene film, and other plastic films similar to polypropylene film used will depend on the manufacturing method, degree of orientation, purity, and other factors recognized by those skilled in the art. It will be appreciated that (within the limits of the nature of the film) it may have higher or lower tensile strength and elongation.

The present invention is not limited only to the embodiments described above, but may allow various changes and improvements without departing from the spirit of the present invention.

Claims (1)

[Scope of Claims] 1. A pressure-sensitive transfer material comprising a plastic film base carrying a solid transfer layer comprising a pressure-sensitive transferable image-forming material that can be transferred to a copy sheet by type pressure, comprising: The plastic film substrate consists of a laminate of two different extruded plastic films A and B, each with a maximum caliper of about 25.4 microns (1 mil), and where the plastic film A has a maximum caliper of about 21.8 Kg/
Stretched and asymmetrically oriented with a tensile strength (MD) greater than 31,000 psi (31,000 psi), an elongation (MD) less than about 60% and a relatively small deformability upon type pressing and low embossing retention. The plastic film B is a polyethylene terephthalate film of about 18.3 Kg/mm^2 (26 .000p
si), an elongation (MD) greater than about 100%, and a deformability around the type pressure surface and embossing retention greater than said plastic film A, and The laminate formed by bonding these two plastic films A and B together with a thin adhesive intermediate layer has better cracking resistance, breakage resistance and tear resistance under type pressure than the plastic film A. 1. A pressure-sensitive transfer material having a larger strength and emboss residue resistance than the plastic film B. 2. The pressure-sensitive transfer material according to claim 1, wherein the plastic film B is a nylon film. 3. The pressure-sensitive transfer material according to claim 1, wherein the transfer layer on the base material has a weak pressure-sensitive transfer property for one-time use. 4. The pressure-sensitive transfer material according to claim 1, wherein the transfer layer on the substrate comprises a porous structure of a synthetic thermoplastic resin containing an image-forming substance in its pores. 5. The pressure sensitive film according to claim 1, wherein the plastic film B is a polypropylene film, and the transfer layer containing the image forming substance is present as a lipophilic wax layer on the polypropylene film and has a strong affinity with the polypropylene film. Transfer material. 6. The transfer layer containing the image-forming substance is formed by coating with a volatile solvent that is a solvent for one component of the laminate,
Claim 1: Solvent bonded with laminate
Pressure-sensitive transfer material as described in section. 7. The pressure sensitive transfer material of claim 1, wherein the plastic film A has a thickness of about 12.7 microns (0.5 mil) to about 25.4 microns (1 mil). 8. The pressure sensitive transfer material of claim 1, wherein the plastic film B has a thickness of about 6.4 microns (0.25 mils) to about 19.1 microns (0.75 mils). 9. The pressure-sensitive transfer material according to claim 1, wherein a transfer layer containing an image forming substance is supported on the surface of the laminate via a thin ink binding layer of synthetic resin.