JPH0767851B2 - Backside printing method of imaging support material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of applying patterns and markings on a polyolefin-coated imaging base paper.

The desired character is conventionally applied by flexographic or engraving on the raw base paper to allow the manufacturer's name or other characterization to be provided on the back side of the polyolefin-coated imaging base paper, The printed side is then covered with clear polyethylene.

In the absence of titanium dioxide in the backside polyolefin coating, the printed surface appears transparent and the overall required opacity is generally the addition of titanium dioxide in the front side polyethylene coating and the raw-base paper. ) Filling. However, the use of certain imaging base papers requires a high degree of opacity, which also requires the addition of titanium dioxide during the backside coating. However, this titanium dioxide addition interferes with the visibility of the printed image.

Two drawbacks arise, especially when using conventional printing methods for characterizing substrate paper and / or for this type of mark formation.

First, automatic detection of photographic paper defects and problems is made difficult by laser methods because these laser methods are affected by the interference created by the printed characters.

Secondly, printing CHARACTER is based on photochemical reactions,
Interference effects associated with the final photographic image that occur on the emulsion coated side can be generated.

Moreover, the use of conventional printing inks requires additional protection steps, including reducing the risk of explosion associated with the solvent contained in the printing ink, and avoiding or preventing ink smearing.

Attempts have already been made to display on polyolefin-coated photographic base paper by means of embossing. For this purpose, the polyethylene-coated paper was passed through a calender, where the calender rollers were provided with a specially structured surface. However, this method of operation proved to be unsuitable for this purpose, since a uniform embossing and depression depth could not be achieved. Furthermore, this method required two separate operations that could not be performed in a single operating step: coating and embossing.

Further, there is a method of using a chilled cylinder roll with a specially made surface to impart a different pattern or code to the back side of the polyolefin coated substrate paper. This chilled cylinder roll allows for polyolefin extrusion coating and characterization in a single operation step in the production line.

This latter method is described, for example, in Agfa-Gevaert Fotobericht N
Japanese Patent Publication No. 61-21833 referenced in o.23 (1988)
No. Polyethylene is extruded onto the carrier through a slot between a pressure roll and a chill cylinder roll. The surface of the chill cylinder roll can be provided with various patterns, for example any kind of characterization, the characterization surface being distinguished by a roughness different from that of the chill cylinder roll itself.

Disadvantages of this method are features of this method, including emulsion desensitization during subsequent processing of the base paper for subsequent coating with photographic emulsion. Furthermore, the readability of the characterizations obtained with the aid of the cooling cylinder rolls used is not very good.

In the context of this method, the polyolefin coating material has the further disadvantage that it obviously does not contain titanium dioxide or other pigments, because pigmentation of the coating material is desired in certain photographic and electrophotographic products. Because.

It is an object of the present invention to provide a method by which it is possible to make a polyolefin-coated imaging base paper which does not have the deficiencies mentioned above.

It is a further object of the present invention to provide a polyolefin-coated backing paper in which the variously patterned backside polyolefin coatings have no effect on the front side of the photographic layer coated backing paper.

These and other objects and advantages of the invention will be apparent from the description below.

According to the invention, a chilled cylinder roll arranged in a line and provided with an etched or engraved pattern or code on its surface is used in the extrusion coating, whereby the pattern to be transferred to the backside polyolefin coating is , Increase of surface level height in certain area of chill cylinder roll,
Alternatively, it is represented by a reduction in height, which is further distinguished by a difference in gloss when compared to the rest of the cylinder roll surface. Especially with respect to the central axis of the roll, the high-lying surface part of the cooling cylinder roll always exhibits a high gloss.

A method of marking or printing on the backside of a polyolefin-coated imaging base paper comprises mounting a pressure roll on a machine frame. The chill cylinder roll has an etched pattern or code on the surface of the chill cylinder roll. Differences in level of height and cooling cylinder roll surface structure exist between patterns or marks etched or engraved on the cooling cylinder roll surface on the one hand and the cooling cylinder roll surface on the other hand. The height difference measured with a chilled cylinder roll is about 3-8 μm. The cooling cylinder roll is placed on the machine frame parallel to the pressure roll,
This forms a nip between the pressure roll and the cooling cylinder roll. The raw substrate paper is passed through the nip between the pressure roll and the cooling cylinder roll. The polyolefin-coated material is provided as a film on the surface of the raw substrate paper through the nip between the chill cylinder roll and the pressure roll, while at the same time generating an image of the surface structure of the chill cylinder roll on the polyolefin wrap. The difference in the chill cylinder roll surface structure causes a difference in gloss of the coated paper between the area corresponding to the pattern on the chill cylinder roll surface and the surrounding area of the chill cylinder roll surface. This difference in gloss between the embossed pattern in the polyolefin coating of the base paper and the area of the coating surrounding the pattern or code is
The higher surface area of the chill cylinder roll causes a higher gloss level to occur in the first area of the coated paper when compared to the second area of the coated paper which corresponds to the lower surface area of the chill cylinder roll. Have a structure.

Preferably, the difference in gloss between the first and second areas on the coated paper is about 20-60, but not less than 15, as measured by ASTM D523 using a measuring head at an angle of 60 °. Yes, about 30-80, but not less than 25, when measured at a measuring head under an angle of 85 °.

The polyolefin coating material forming the film may include polyethylene or polypropylene and may include a pigment. The pigment can be any known pigment and is preferably selected from the group consisting of titanium dioxide, carbon black, cobalt blue, any other colorant and mixtures thereof. The amount of titanium dioxide can be 0 to 15% by weight of the polyolefin coating material. The applied amount of polyolefin-coated material can be in the amount of about 20-60 g / m ² .

The difference in height level measured on the surface of the cylinder roll is about 3
It can be ˜8 μm.

Surprisingly, it was found that the pattern or code imprinted on the back side polyolefin coating did not cause the embossed pattern or code on the back side polyolefin coating to cause a dip in the front side of the coated substrate paper, And in this case the pattern or code imprinted on the back side polyolefin coating is of constant height level and gloss between the patterns or codes etched or engraved on the cooling cylinder roll surface on the one hand and the cooling cylinder roll surface on the other hand. It was found that the difference was maintained, and further no fog, veil or desensitizing effect was observed in the photographic or electrophotographic layer (imaging layer) applied to the front side of the paper later.

Furthermore, the effect of the present invention is enhanced and increased when not only maintaining a constant loading of the polyolefin coating but also maintaining a constant pigment content in the coating.

The difference in height level according to the invention is an amount of about 3-8 μm, as measured on a chilled cylinder roll.

The gloss difference according to the invention is represented by the gloss difference between the surface of the pattern or code embossed in the polyolefin coating of the substrate paper and the area of the coating surrounding the pattern or code, where the gloss difference is 60 °. Not less than 15 when measured with a measuring head having a measuring geometry, and not less than 25 when measured with a measuring head having a measuring geometry of 85 °. The preferred gloss difference is 20-at the measurement angle of 60 °
It can vary in the range of 60 and can vary from 30 to 80 when measured at a measuring angle of 85 °.

According to the invention, the amount of polyolefin coated material applied is 20.
There amounts to 60 g / m ^2, titanium dioxide content in the coating material in an amount of 0-15 wt%. The preferred application amount of polyolefin on the raw base paper is an amount of 25 to 50 g / m ² .

No technical problems with the sticking of polyethylene particles on the surface of the chill cylinder roll during coating have been observed when working according to the invention.

Polyethylene has its low density (LD) or its high density (H
Both forms D) can be used, or polypropylene can be used to obtain the polyolefin coating of the imaging base paper.

For pigmentation of polyolefin-coated materials, titanium dioxide can be used in its rutile or anatase modification, as well as other color pigments, such as carbon black or cobalt bull.

The novel features which are considered as characteristic of the invention are set forth in the appended claims. However, together with other objects and advantages, the present invention of its product and its manufacturing method will be best understood from the following specific embodiments and examples when read in combination with the accompanying drawings.

In the accompanying drawings some of the various possible embodiments of the invention are shown.

FIG. 1 is a side elevational view of an apparatus for making polyolefin coated imaging base paper.

FIG. 2 is a perspective view of a chilled cylinder roll used in accordance with the present invention, showing a schematic view of a possible raised surface having high gloss.

FIG. 3 is a top plan view on a portion of the surface of a chilled cylinder roll used in accordance with the method of the present invention.

FIG. 4 is a partial cross-sectional view of a cooling cylinder roll used in accordance with the present invention showing a raised surface having high gloss.

FIG. 5 is a partial cross-sectional view of a chill cylinder roll used in accordance with the present invention showing a concave surface having a relatively low gloss.

FIG. 6 is a cross-sectional and dimensionally modified schematic view of a cooling cylinder roll used in accordance with the present invention showing a raised surface having high gloss.

FIG. 1 shows a schematic diagram of a conventional plant for extrusion coating. A similar plant is described, for example, in US Pat. No. 3,959,546. As can be seen in FIG. 1, a roll of imaging base paper 10 of constant width exits the storage roller 12 through a nip 14, which is formed by a cooling cylinder roll 16 and a pressure roll 18. It Cooling cylinder roll 16
Is mounted in the machine frame 48. Imaging base paper 10
The continuous sheet of passes through the nipple 14. The pressure generated between the pressure roll 18 and the cooling cylinder roll 16 is about 25 to 300 liters.
The linear pressure is bs / in. The temperature of the chilled cylinder roll 16 is 10-40 ° C, preferably about 70 ° F or 20 ° C.

A method of marking or printing on the backside of a polyolefin coated imaging base paper uses a polyolefin coated material as a film between a chill cylinder roll having an etched pattern or code on the surface of the chill cylinder roll and a pressure roll. It is brought through the nip onto the surface of the raw substrate paper and at the same time the surface structure of the cooled cylinder roll is obtained. The difference in height level and gloss lies between the chill cylinder roll face on the one hand and the etched or engraved pattern or code on the chill cylinder roll on the other hand. The height level difference measured with a chilled cylinder roll is about 3-8 μm. The gloss difference is represented by the gloss difference between the pattern imprinted in the polyolefin coating of the blank paper and the area of the coating surrounding the pattern or code. The high surface area of the chill cylinder roll is always associated with high gloss.

The gloss difference between the coated surface and the pattern or code stamped on it is not less than 15 according to ASTM D523, measured with a measuring head having an angle of 60 ° and 25 measured at an angle of 85 °.
That is all. Preferred gloss differences can range from 20 to 60 when measured at an angle of 60 °, and can range from 30 to 80 when measured at an angle of 85 °.

The polyolefin coating material can contain at least polyethylene or polypropyne and a pigment. The pigment can be selected from the group consisting of titanium dioxide, carbon black, cobalt blue, other colorants and mixtures thereof. The amount of titanium dioxide can be 0 to 15% by weight of the polyolefin coating material. Approximate application amount of polyolefin-coated material
It can be in an amount of 20-60 g / m ² .

An apparatus for forming marks on the backside of a polyolefin-coated imaging base paper has a machine frame, a feed roller that provides a continuous stock base paper, a pressure roller and a cooling cylinder mounted on the machine frame. The chilled cylinder roll has an etched pattern or code in its surface. The height level and cooling cylinder roll surface structure differences are between the cooling cylinder roll on the one hand and the pattern or code etched or engraved on the cooling cylinder roll on the other hand. The height level difference measured with a chilled cylinder roll is about 3-8 μm. The cooling cylinder roll is arranged on the frame parallel to the pressure roll, thereby forming a nip between the pressure roll and the cooling cylinder roll. The take-up roller is arranged parallel to the cooling cylinder roll. The take-up roller draws the raw material base paper from the supply roller through the nip between the pressure roll and the cooling cylinder roll, and uses the polyolefin-coated material as a film passing through the nip between the cooling cylinder roll and the pressure roll. It is brought to the substrate paper and at the same time produces an image of the surface structure of the chilled cylinder roll on the polyolefin coating. The cooling cylinder roll surface structure difference causes a difference in gloss of the coated paper between the area corresponding to the pattern on the cooling cylinder roll surface and the peripheral area of the cooling cylinder roll surface. This difference in gloss between the embossed pattern in the polyolefin coating of the base paper and the area of the coating surrounding the pattern or sign is compared with the second area of the coated paper which corresponds to the lower placement surface area of the chill cylinder roll. When applied, it has a structure that results in the generation of high gloss levels in the first area on the coated paper.

The imaging base paper contains a central source base cellulose paper.
The front layer of polyolefin is laminated to the front side of the central raw material cellulosic paper. The polyolefin backside layer has an area of high gloss level in the first area on the backside of the imaging base paper,
Laminated on the backside of the central stock substrate cellulose paper which has a low high level area in the second zone on the backside of the imaging base paper surrounding the first zone.

An amount of about 20-60 g polyolefin per 1 m ² can form the backside layer. The thickness of the coated polyolefin in the first area is
It can be at least about 10% greater when compared to the second area to provide a uniform level of indentation at the interface between the raw substrate paper and the polyolefin backside layer.

The polyolefin film 20 is extruded from the extruder 22 into the nip 14, whereby it simultaneously adheres to one side of the paper and receives the image of the surface structure of the chill cylinder roll 16 on the other side.

The surface of the cooling cylinder roll is shown in FIG. The surface of the pattern 38 provided on the cooling cylinder roll 16 exhibits a higher gloss than the area 40 around the pattern 38.

The coated imaging substrate paper 24 exits the chilled cylinder roll 16 and leads to a winder 26.

FIG. 2 shows a perspective view of such a pattern 52 on the cooling cylinder roll 50 in which the marks to be provided on the imaging paper can be placed on the cooling cylinder roll 16 if desired.
In particular, FIG. 2 provides a multiple repeating pattern 52.

4 and 5 show a part of the cross section of each pattern.
The difference in height level of the present invention between the glossy outer surface 34, 54 and the low gloss inwardly facing surface 36, 56 is indicated by Δh. The surface placed facing outward shows high gloss,
Brighter than the rest of the chilled cylinder roll.

The structure of the cooling cylinder roll surfaces 28, 30, 32 can be made in various ways, for example by etching the surface of the steel cylinder outside the area of the pattern surface, which is patterned against the rest of the surface. Compare FIGS. 4 and 6, which results in a surface structure with an increase or protrusion in it. Alternatively, see FIG. 5, where the pattern formed can be viewed as depressions that represent a more inwardly disposed face 36 on the cylinder face. FIG. 6 has been modified so that the height of the raised region is very high and is shown dimensionally when compared in relation to the remaining dimensions of FIG. The cooling cylinder roll surface is processed, for example, by US Pat. No. 330028.
It can be carried out by various methods such as the method described in No. 6. After the etching process, the cooling cylinder roll is plated with chrome.

It is important that the outer surface of the cooling cylinder roll is a high-gloss surface with respect to the axis of the cooling cylinder roll. The low gloss surface is placed on the chill cylinder roll at a level close to the chill cylinder roll axis. The difference between the outer radii of the high gloss outer surface and the low gloss surface can be about 3-8 μm, preferably about 3-6 μm. The level of measurement of each layer is at the outer level of the surface, i.e. at the top of said layer in the case of rough or low gloss surfaces.

Example 1 A raw material base paper made by a conventional method having a basis weight of 175 g / m ² was prepared as shown in FIG. 2 and FIG.
(See table) with a chilled cylinder roll (see table) fed into the laboratory extrusion plant shown schematically in FIG. 74% polyethylene with a density of 0.950 g / cm ³ of Alathon 7250 made in DuPont de Nemours and Company, Wilmington, Del., And XEC-8457 dioxide made from Natech Corporation. A 26% titanium / polyethylene master batch mixture was extruded and laminated to paper using a linear pressure in the nip of about 60 lbs / in. The polyethylene coating weight was 50 g / m ³ . The raw substrate paper coated in this way was tested by the method described below. The results are shown in Table 1.

Example 2 A laboratory extrusion plant schematically shown in FIG. 1 with raw base paper having various basis weights shown in Table 1 and having chilled cylinder rolls of type B (see Table 2) shown in FIG. Supplied to. The same mixture used in Example 1 was used for extrusion coating. Polyethylene coating weight is 18-50g / m ³
Changed. The test results are shown in Table 1.

The raw material substrate paper having a basis weight of Example 3 175 g / m ^3, the laboratory extrusion plan schematically illustrated in Figure 1 having a cooling cylinder roll type shown in FIG. 3 C (see Table 2) Supplied.
The other conditions corresponded to those in Example 1. The test results are shown in Table 1.

Example 4 A raw substrate paper having a basis weight of 175 g / m ³
It was fed into the laboratory extrusion plan outlined in Figure 1 with a chilled cylinder roll (see Table 2). The other experimental conditions corresponded to those of Example 1. The results are shown in Table 1.

Example 5 (Comparative) A raw substrate paper having a basis weight of 175 g / m ³ as described in Example 1 was coated with a polyethylene coated material according to the method of Example 1. The cooling cylinder roll was type E (see Table 2) and was approximated corresponding to the cylinder used by Japanese Examined Patent Publication No. 61-21833. The results are shown in Table 1.

Test methods for the study of base papers coated according to the invention 1. Sensitometric studies A sample of imaging base paper coated with polyolefin according to the invention in the form of strips of size 9x20 cm in a conventional photographic color. The side with the embossed pattern in the polyolefin coating, now in contact with the paper, was placed on the side of the photographic emulsion coated color paper.

The strips so applied were packaged in black inked polyethylene coated sacks or bags (which weighed 15 kg) and stored at 35 ° C for 1 week.

The samples were then developed without exposure to determine the presence of possible fog, veil or cloud, and they were exposed and developed to determine the possible desensitization of the emulsion.

2. Pressure Effect Since the polyolefin coated imaging base paper is made as a roll product, the pressure generated inside the roll must be taken into account. For this reason, a series of investigations were carried out using a laboratory press to test the possibility of transferring the embossed pattern on the back side to the front side of the paper. The pressure was applied in a laboratory press in an amount of about 1.5 Kg / cm ² , which pressure was approximately comparable to the pressure expected in the roll.

3. Gloss measurement The study is according to standard test for specular gloss ASTM D523-7
It was carried out using a Lange reflectometer in close proximity to the criterion of 8.
Measurements include comparisons at 60 °, 20 ° or 85 ° configurations. The 60 ° configuration is useful for internal comparison of most samples. The 85 ° configuration is used to compare samples against sheen or near grazing shininess. It is especially used when the sample exhibits a low gloss 60 ° value, for example less than 10.

Specular gloss is the relative luminous reflectance of the sample in each specular reflection direction. The luminous reflectance is the ratio of the luminous flux reflected from the sample (to its incidence) for a specified solid angle.

The measurements were carried out using a measuring head in a measuring arrangement of 85 ° for low gloss surfaces and 60 ° for standard gloss surfaces.

It will be appreciated that each of the above-described elements, or two or more thereof, may be usefully employed in alternative types of chill roll processing equipment than those of the type described above.

Although the present invention has been embodied and described in the context of a chill roll printing process for imparting a pattern or code on a polyolefin coated imaging base paper, it is not so limited as to any departure from the scope of the present invention. This is because various modifications and structural changes can be made without doing so.

[Brief description of drawings]

FIG. 1 is a side elevational view of an apparatus for making polyolefin coated imaging base paper, FIG. 2 is a perspective view of a chilled cylinder roll used in accordance with the invention, and a schematic representation of a possible raised surface with high gloss, 3 is a top plan view of a part of the surface of the cooling cylinder roll used by the method of the present invention, FIG. 4 is a partial cross-sectional view of the cooling cylinder roll used by the present invention showing a rising surface having high gloss, FIG. Is a partial cross-sectional view of the cooling cylinder roll used according to the present invention showing a concave surface having a relatively low gloss, and FIG. 6 is a cross-section and dimensions of the cooling cylinder roll used according to the present invention showing a rising surface having a high gloss. It is the schematic diagram deformed mechanically. 10 …… Image forming base paper, 12 …… Storage roll, 14 …… Nip, 16 …… Cooling cylinder roll, 18 …… Pressure roll,
20 …… Polyethylene film, 22 …… Extruder, 24 …… Coated image forming base paper, 26 …… Winding device, 34,54 …… Gloss outer surface, 36,56 …… Arranged inward Surface, 50 …… Cooling cylinder roll, 52 …… Pattern, 48 …… Frame.

Claims (17)

[Claims] 1. A polyolefin-coated material is provided as a film on the surface of a raw substrate paper by passing through a nip between a cooling cylinder roll and a pressure roll having a pattern or code etched on the surface of the cooling cylinder roll, and at the same time. A method of marking or printing on the backside of a polyolefin coated imaging substrate paper adapted to obtain an image of the surface structure of a chilled cylinder roll, the difference in height and the difference in gloss on the one hand on the chilled cylinder roll side and on the other hand. Provided between the cooling cylinder roll surface and the pattern or code etched or engraved,
As a result, the height difference measured by the cooling cylinder roll is 3 to 8 μm, and the difference in gloss is embossed in the polyolefin coating of the base paper and the gloss between the areas of the coating surrounding the pattern or code. It is expressed by the difference of
A method characterized in that the high-lying surface part of the cooling cylinder roll is always combined with high gloss. 2. The difference in gloss between the coated surface and the pattern or code stamped thereon is according to ASTM D523 60.
2. The method according to claim 1, wherein the measurement is carried out at a measuring head having an angle of 15.degree. Or more and at the angle of 85.degree. 3. A gloss difference of 20 when measured under an angle of 60 °.
It is in the range of ~ 60 and 30 ~ when measured under an angle of 85 °.
The method of claim 2 in the range of 80. 4. The method of claim 1, wherein the polyolefin coating material comprises at least polyethylene or polypropylene. 5. The method according to claim 1, wherein the polyolefin coating material contains at least polyethylene or polypropylene and a pigment. 6. The method of claim 5 wherein the polyolefin coating material contains at least one pigment selected from the group consisting of titanium dioxide, carbon black, cobalt blue, other colorants, and mixtures thereof. 7. The method according to claim 6, wherein the amount of titanium dioxide is 0 to 15% by weight of the polyolefin coating material. 8. The weight of the polyolefin coating applied is 20-60 g /
The method according to claim 1, which is m ² . 9. A machine frame; a supply roller for supplying a continuous raw material base paper; a pressure roll mounted on the machine frame; and a cooling cylinder roll mounted on the machine frame,
The cooling cylinder roll has an etched pattern or code on its surface, the height level and the cooling cylinder roll surface between the cooling cylinder roll surface on the one hand and the pattern or code etched or engraved on the cooling cylinder roll surface on the other hand. There is a structural difference so that the height level difference measured by the cooling cylinder roll is about 3-8 μm, the cooling cylinder roll is arranged on the frame in parallel with the pressing roll, and the pressure is applied by this. Forming a nip between the roll and the cooling cylinder roll; pulling the raw substrate paper from the feed roller through the nip between the pressure roll and the cooling cylinder roll, and passing through the nip between the cooling cylinder roll and the pressure roll As a film, bring the polyolefin coating material onto the surface of the raw substrate paper, and at the same time A winding roller is arranged parallel to the cooling cylinder roll to generate an image of the surface structure of the cooling cylinder roll on the coating, and the difference in the cooling cylinder roll surface structure corresponds to the pattern on the cooling cylinder roll surface. And the surrounding area of the chill cylinder roll surface, causing a difference in gloss of the coated paper and this pattern between the embossed pattern in the polyolefin coating of the base paper and the area of the coating surrounding the pattern or code. When the gloss difference is compared to the second area of the coated paper where the higher surface area of the chill cylinder roll corresponds to the lower surface area of the chill cylinder roll, the higher gloss level in the first area of the coated paper An apparatus for forming marks on the back side of a polyolefin-coated image forming base paper, characterized in that it has a structure that causes generation. 10. A central raw material-based cellulose paper; a front layer laminated on the front side of the central raw material-based cellulose paper; and a polyolefin backside layer laminated on the back side of the central raw material-based cellulose paper. An imaging base paper having an area of high gloss level in a first area on the back side of the imaging base paper and an area of low gloss level in a second area on the back side of the imaging base paper. 11. An image according to claim 10, wherein the gloss difference between the first and second areas of the coated paper is about 20 to 60 as measured by ASTM D523 under a measuring head at an angle of 60 °. Forming base paper. 12. The imaging group of claim 11 wherein the gloss difference between the first and second areas on the coated paper is about 30-80 as measured by ASTM D523 under an angle of 85 °. Material. 13. An imaging substrate according to claim 10 wherein the gloss difference between the first and second areas on the coated paper is about 30-80 as measured by ASTM D523 under an angle of 85 °. paper. 14. The imaging base paper according to claim 10, wherein the polyolefin coating material forming the film comprises polyethylene or polypropylene. 15. The imaging base paper according to claim 10, wherein the film-forming polyolefin coating material comprises polyethylene or polypropylene and a pigment. 16. The imaging base paper according to claim 15, wherein the pigment is selected from the group consisting of titanium dioxide, carbon black, cobalt blue, other colorants, and mixtures thereof. 17. Polyolefin in an amount of about 20-60 g / m ² forms a backside layer; to provide a uniform level of indentation at the interface between the backside layer of polyolefin and the raw substrate paper to provide a level of coating polyolefin in the second area. The imaging substrate paper of claim 10, wherein the thickness is at least about 10% greater than the first area.