JP3210969B2 - Cross-section preparation of paper or printed matter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cross section of paper or printed matter. More specifically, the present invention relates to a method for producing a cross section by irradiating paper and printed matter with an ion beam.

[0002]

2. Description of the Related Art The surface and internal structure of paper, the distribution of additives and the like in the thickness direction, and the distribution of pigments and binders on coated paper, etc., are known as paper properties, such as strength properties, optical properties, and the like. It is an important factor that directly affects the surface smoothness and printability. On the other hand, the printability of the paper, such as the state of ink transfer and the state of penetration during printing, is affected by these paper characteristics. Therefore, in order to analyze the relationship between paper characteristics and ink transferability, it is necessary to accurately grasp the paper structure from cross-sectional observation. Conventional cross-section preparation methods used for obtaining information on the structure of paper include a cutting method using a blade, a resin embedding method, a freeze embedding method, a freeze splitting method, and an ion etching method.

The cutting method using a blade is a method for cutting with a sharp blade (a double-edged razor or the like), which allows easy selection of a cut portion and is effective for observation at a low magnification. Japanese Patent Application Laid-Open No. 72084 (a sample preparation apparatus for a scanning electron microscope) is available. However, there is a problem that structural destruction in a minute portion is remarkable and the cut surface has poor smoothness.

Therefore, there is a resin embedding method as a generally used method for avoiding structural destruction when cutting out a cross section. This allows the sample to be paraffin, wax,
After embedding with various synthetic resins (epoxy resin, methacrylic resin, etc.), it is a method of cutting with a microtome or ultramicrotome glass knife. In the case of observing the paper layer structure of the paper at a low magnification using an optical microscope, the fiber portion and the void portion can be clearly observed without causing the paper structural breakage. However, the analysis of the state of fine fibers, fillers, coating agents or ink permeation in the paper layer,
When a cross section is observed at a high magnification using a scanning electron microscope (hereinafter, referred to as SEM), a good image with contrast cannot be obtained unless the embedded resin is removed. For this reason, a method has been adopted in which the embedded resin of the section obtained by cutting is removed with a solvent or an alkaline solution or the like, and then observed. However, when the embedding resin is removed, the fibers may slightly swell due to a solvent or an alkaline solution or the like, and the structural change of the paper layer may occur.

[0005] In order to eliminate such a structural change of the paper layer when the embedding resin is removed, there is the above-mentioned freeze embedding method as a method for observing at a high magnification with an SEM while embedding the resin. Japanese Unexamined Patent Publication (Kokai) No. 2-259449 (a method for cutting paper slices) is known. This is a method of embedding using a frozen embedding agent containing cellulose as a main component, and cutting an embedding sample with a steel knife. Since the embedding material is soft, it is possible to obtain a wide range of sections while embedding. However, there is a problem that a slight amount of water is contained in the cellulosic embedding medium, which causes a slight swelling.

On the other hand, when analyzing the transfer state and the permeation state of the printing ink to the paper, the ink embedded in the paper melts in the above-described resin embedding method. Can not. For this reason, there is a problem that the cross section of the ink layer transferred to the paper surface cannot be directly observed. When analyzing the permeation state of printing ink into paper, a very difficult method is used, in which the paper layer is separated into several layers and the permeation state of the ink layer into the paper layer is analyzed based on the ink adhesion state of each layer. Had been. In addition, this method has a problem that the permeation state of the ink cannot be accurately replaced with a position in the paper layer because the structure is destroyed when the paper layer is peeled off.

[0007] As one of the above-mentioned freeze breaking methods, there is an ethanol freeze breaking method. In this method, a paper sample is placed in a capsule containing ethanol, and the ethanol and the paper sample are frozen together with the capsule in liquid nitrogen, and then the paper is cut together with the capsule to obtain a cross-sectional surface. When trying to make a cross section of paper by this method, individual fibers are cut as a smooth cross section, but since the fibers are laminated in layers, a smooth cross section can be obtained as a whole paper. However, there is a problem that the paper layer structure cannot be observed.

In the ion etching method, after a cross section is cut out with a microtome or the like, the cross section layer broken by a blade is etched by an ion sputtering apparatus, and the broken cross section layer is removed to expose the internal structure of the sample. Is the way. This method has a problem that the structure of the paper is changed because heat is generated when argon ions are continuously irradiated by the ion sputtering apparatus. In order to prevent this structural change due to heat, it was necessary to suppress the rise in temperature by intermittently irradiating argon ions, or to fix by embedding resin or osmium staining. However, when argon ions are intermittently irradiated, it takes a long time for ion etching, and when embedded in a resin, the printing ink dissolves as described above, and the state of transfer to paper cannot be observed. There was a problem.

Further, in the above-described conventional cross-section manufacturing method by embedding, since the cut-out position cannot be designated, in order to observe and analyze the structure at the designated position, the cross-section fabrication operation and the observation are repeated. And it takes a lot of time and effort.

[0010]

Conventionally, when observing the internal structure of paper with an optical microscope, the paper layer structure is observed and analyzed by a method of cutting the paper with a microtome after embedding the paper with a resin. Was possible. However, the optical microscope is limited to macroscopic observation of the cross section, and the cutout position cannot be specified. Therefore, in order to observe and analyze the structure at the specified position, it is very necessary to repeat the work of manufacturing the cross section. It took a lot of effort. Recently, SEM
When observing a cross section at a high magnification using a method, it is difficult to perform high-resolution observation while the resin is embedded, so that the resin embedded in the section cut by the method described above is removed with a solvent or an alkaline solution. After that, the observation method is adopted. For this reason, when removing the resin embedding, there is a problem that the fibers slightly swell due to a solvent or an alkaline solution or the like, and the structural change of the paper layer occurs.

On the other hand, when analyzing the transfer state and permeation state of the printing ink to the paper, it is necessary to embed the resin in the resin embedding method because the ink transferred to the paper melts out in the resin embedding method described above. Can not.

The focused ion beam [hereinafter referred to as FIB (Focused Ion Bea) used for preparing the cross section of the paper or printed matter of the present invention.
m). The apparatus is used for performing local processing of semiconductors and metals, etc., as in the present invention, the paper layer structure of the paper, the distribution of chemicals added to the paper in the thickness direction,
As a means for analyzing the coating layer structure of the coated paper, the state of transfer of the printing ink to the paper, and the like, there has been no report yet of using the FIB apparatus for producing a cross section of paper or printed matter. The inventor of the present invention has conducted intensive studies and found that the FIB apparatus characterized by local processing with a thickness of several μm has a thickness of 100 μm.
We found that it was possible to produce a cross section of paper or printed matter of about μm, and set the parameters of the accelerating voltage, beam current and beam diameter of the focused ion beam to the conditions for roughing and finishing using this device. By irradiating, it is possible to cut out the cross-section of paper or printed matter with an accuracy that is incomparable with the conventional technology, causing structural destruction of the paper layer, the coating layer and the printing ink layer transferred to the paper. Instead, the purpose is to cut out a cross section at a designated position, and a remarkable improvement has been achieved as compared with the conventional cross section manufacturing method used in the above-mentioned conventional technology.

[0013]

In order to achieve the above object, the present invention provides an ion source (1), a monitor (4) for observing a sample, and setting a cutout area and a cutout position, an acceleration voltage, a beam current, Operation unit (5) for setting beam diameter cross-section processing conditions, focusing lens (2), beam limiting aperture
The paper or printed matter (10) is placed on the sample holder (1) by using a focused ion beam device composed of the following components: (6) , a deflector (7), an objective lens (8), and a secondary electron detector (9).
1) and set from the sample insertion slot (3), and irradiate the whole sample of paper or printed matter (10) with ions (12) emitted from the ion source (1), and then use the secondary electron detector (9). While observing the secondary electron image detected by the monitor (4) on the monitor (4), at the same time, a cut-out area and a cut-out position are specified for the observed image on the monitor (4), and acceleration is performed by the operation unit (5). By setting the cross-section processing conditions of voltage, beam current, and beam diameter to rough processing and finish processing conditions, the ions (12) emitted from the ion source are narrowed down by the focusing lens (2), and the beam limiting aperture (6) is used. )
After the ion beam is controlled by, the deflector (7) scans, and the objective lens (8) narrows down the ion beam and irradiates it to a designated position on paper or printed matter (10) to process the paper or printed matter. Producing a cross section at the cutout position without causing damage or temperature rise, and without changing the structures of the paper layer, the coating layer, and the printing ink layer transferred to the paper. It is.

Further, in the above-mentioned method for producing a cross section of paper or printed matter, the ion beam is gallium.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a cross section of paper or printed matter according to the present invention, the paper or printed matter is irradiated with an ion beam,
While observing the secondary electron image detected by the secondary electron detector on the monitor, at the same time, specify the cut-out area and cut-out position for the observed image on the monitor, and operate the acceleration voltage, beam current, and beam with the operation unit. Rough processing of diameter cross-section processing conditions,
Finish processing conditions are set, and a rough processing is performed by irradiating an ion beam in an amount necessary for cutting the cut area and the specified position of the cut position. Further, as a finishing process for improving the accuracy of the cross-section processing, by irradiating a beam narrower than the rough processing, a smooth cross-section that can be observed even at a high magnification using a scanning electron microscope is produced.

In the processing of paper or printed matter by the above-mentioned ion beam, no shear stress, compressive stress and tensile stress as observed in machining such as cutting and polishing are generated.
For this reason, a sharp cross section can be produced even for a composite material in which materials having different hardness and brittleness are mixed or a material having voids, that is, paper or printed matter. Therefore, when observing the paper layer structure or the coating layer structure of the paper and the coated paper, the observation can be performed without causing the structural destruction of the paper layer and the coating layer at the designated position. Furthermore, even when observing the printing ink layer transferred to the paper by printing, the transfer state of the ink transferred to the paper surface at the designated position can be directly observed in cross section.

The method for producing a cross section of paper using a focused ion beam according to the present invention effectively works for analyzing the paper layer structure, the coating layer structure, and the transfer state of the printing ink transferred to the paper.

The paper used in the present invention includes handmade paper,
Needless to say, it includes machine-made paper, coated paper, non-woven fabric and the like.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In this embodiment, gallium is used as the ion source. However, the present invention is not limited to this, and any ion source generally used for semiconductor fine processing may be used.

Embodiment 1 FIG. 1 is an external view (a) of a focused ion beam apparatus used in the present invention, and is a schematic view (b) of the inside of the apparatus. In FIG. 1, (1) is a liquid gallium ion source, (2) is a focusing lens unit, (3) is a sample insertion port, (4) is a monitor for setting operation conditions and a monitor for observing a sample, and (5) is a monitor. This is an operation unit for setting cross-section processing conditions. Using the device, paper or printed matter (1
0) is attached to the sample holder (11) and set from the sample insertion port (3), and the ions (12) emitted from the ion source (1) are irradiated on the entire sample of paper or printed matter (10), While observing the secondary electron image detected by the secondary electron detector (9) on the monitor (4), at the same time, specifying the cutout area and the cutout position for the observed image on the monitor (4), By setting the acceleration voltage, beam current and beam diameter in the section (5), the ions (12) emitted from the ion source (1) are narrowed down by the focusing lens (2) and limited by the beam limiting aperture (6). After that, scanning was performed by the deflector (7), and the ion beam was narrowed down by the objective lens (8) to irradiate a designated position on the paper or printed matter (10).

FIG. 2 is a secondary electron image photograph obtained by observing the state before cutting out the cross section of the printed matter with the monitor (4).
In FIG. 2, (A) is a printed matter, (13) is a section of the printed matter on paper, (14) is a paper surface part of the printed matter, and (15) is an ink transfer portion printed on the paper surface of the printed matter. . While observing, on the monitor (4), a position to be cut out as a cross section of the printed matter (A), at the same time, a cut-out line (x) and a cut-out area (y) for an observed image on the monitor (4). Is specified, and the acceleration voltage is set to 30 kV or more, the beam current is set to about 10 nA, and the beam diameter is set to about 300 nm by the operation unit (5)
The gallium ion beam was focused and irradiated while scanning to perform rough processing. Next, in order to increase the processing accuracy, the acceleration voltage was set to 30 kV or more, the beam current was set to 0.3 nA or less, and the beam diameter was set to 30 nm or less.

FIG. 3 is a secondary electron image photograph obtained by observing the cross section of the printed matter (A) by the above-described method and observing the same with the monitor (4). As is apparent from FIG. 3, the printed material cross section of the cut-out line (x) designated in FIG. 2 could be cut out with high positional accuracy. With the conventional cross-section preparation method, it is not possible to specify the position at the time of cutting out, so to find the target position, the work of cutting and observing must be repeated, requiring a lot of time and labor. However, in FIB, since the position at which the cross section is to be formed can be designated, the work time and labor can be significantly reduced. The processing thickness of FIB has been said to be several microns in the field of semiconductor and metal processing, but by setting the processing conditions as described above, the cross-section processing of paper having a thickness of about 100 μm is possible. It was confirmed that it was possible.

(Example 2) FIG. 4 shows that the sheet (B) is focused on a gallium ion beam under the same conditions as in Example 1 to form a cross section, then the sheet is taken out from the FIB apparatus, and the section of the sheet is subjected to SEM. 5 is an electron micrograph observed by the method shown in FIG. In FIG. 4, (16) is a fiber portion in the paper layer,
(17) is a void portion in the paper layer. The paper cross-section opening can cut out a smooth cross-section, and the fiber cross-section (1
5) is not crushed and the fiber portion (1) in the paper layer
It was possible to accurately observe the interface between 6) and the void portion (17). In the cross-section processing by the FIB, there was no structural destruction such as when cutting by a cutting method using a blade, and no structural change due to a temperature rise as in the case of continuous irradiation with argon ions. Since this is based on the collision between ions and atoms, as described above, no shear stress, compressive stress, and tensile stress as observed in machining such as cutting and polishing are generated. In addition, the irradiated ions lose energy while bouncing off the sample atoms in the sample,
The damage depth of the sample atoms is considered to be about 10 nm, as estimated from the ion penetration depth. Furthermore, since the sample temperature at the time of irradiation of the focused ion beam was less than 40 ° C., it is considered that even a material that is weak to heat, such as paper or a coating binder, hardly suffers processing damage in the cross section. Due to such advantages of the FIB, a sharp cross section could be produced even with a material such as paper having voids without causing structural destruction of the paper layer.

(Comparative Example 1) FIG. 5 is a cross-section cut by a cutting method using a blade, which is one of the conventional cross-section preparation methods. The paper (B) is sandwiched between thin films to prevent structural destruction of the paper layer. It is an electron micrograph which observed the cross section of this paper by SEM after cutting it out with a sharp blade so that it might be made as small as possible. In FIG. 5, (18) is a fiber portion in the paper layer, and (19) is a void portion in the paper layer. The cross-sectional surface of the fiber cross-section portion (18) in the paper layer was crushed by the sharp blade cut out, and it was observed that the fibers were flushed in the direction cut by the sharp blade (the direction of the arrow). Therefore, the fiber portion (18) and the void portion (19) in the paper layer
Could not be accurately observed.

(Example 3) FIG. 6 (a) shows a double coated paper (C) formed by focusing a gallium ion beam under the same conditions as in Example 1 to form a cross section. It is an electron micrograph which observed the cross section of this double coated paper by taking out the industrial paper by SEM. In FIG. 6A, (20) is a fiber which is a base material of a double coated paper,
(21) is a void portion in the paper layer, (22) is an internally added filler, (23) is a top coating layer of double coated paper, (24)
Is the undercoat layer of double coated paper. The cross section of the prepared double coated paper (C) shows the shape of the lumen in the fiber (20) and the distribution state of the internally added filler (22) in the paper layer.
In addition, the interface between the fiber portion (20) and the void portion (21) can be accurately observed, and the top coating layer (2
It was clearly observed that two layers, 3) and the undercoat layer (24), were coated. The materials constituting the double coated paper (C) are materials having different components such as fibers (20), fillers (22), and different types of coating pigments (23, 24). Although the hardness and brittleness should be different, a uniform cross section could be obtained without any problem in producing a cross section by FIB.

FIG. 6B is an electron micrograph of a cross section of the double coated layer of the double coated paper (C) in FIG. In FIG. 6B, (23) is a top coated layer of double coated paper, and (24) is an under coated layer of double coated paper. From the pigment particle shape of the double coating layer, it can be seen that different pigments are used in the top coating layer (23) and the under coating layer (24). Also, by comparing the secondary electron data detected by the SEM with the results of the elemental analysis, the under-coated layer (24) is coated with inexpensive heavy calcium carbonate, and the top-coated layer (2
In 3), it was analyzed that calcium carbonate and kaolin having different particle shapes were coated with good dispersion. Further, it is possible to observe the distribution state of the binder by labeling the binder of the coating layer with osmium or the like and performing a surface analysis of the osmium or the like with an elemental analyzer. Through such analysis and analysis, this method can be applied to the study of binder migration (the transition state of the binder component) and the like. Further, by changing the coating conditions, the coating quality due to the difference in the coating process can be improved. It can also be used as a way to clarify the effects.

Comparative Example 2 FIG. 7 is a cross-section cut by a cutting method using a blade, which is one of the conventional cross-section preparation methods. Double coated paper (C) is sandwiched between thin films to form a paper layer. It is the electron micrograph which observed the cross section of the double coated paper cut out by the sharp blade so that structural destruction was made as small as possible by SEM. In FIG. 7, (25) is a fiber which is a base material of the double coated paper, (26) is a void portion in the paper layer, and (27) is a coated layer of the double coated paper. The cross section of the cut double coated paper (C) has its cross section surface crushed by a sharp blade, and in the paper layer, the shape of the lumen in the fiber, the distribution state of the internally added filler, and the fiber portion (2)
The interface between 5) and the void portion (26) could not be accurately observed. Also, the shape and distribution of the pigment could not be observed in the coating layer.

(Example 4) FIG. 8 shows that a gravure printed matter (D) is focused on a gallium ion beam under the same conditions as in Example 1 to form a cross section, and then the gravure printed matter is taken out of the FIB apparatus and the cross section is taken out. It is the electron micrograph which expanded the cross section of the ink transfer layer of the gravure printed matter observed by SEM. In FIG. 8, (28) is an ink transfer portion printed on the paper surface of the gravure print (D),
(29) is a coating layer of gravure printing paper, and (30) is a fiber serving as a substrate of gravure printing paper. As described above, when embedding a resin in order to observe the transfer state of the printing ink, the ink melted out and the ink transfer state could not be observed. It became possible for the first time to directly observe the cross section of the ink layer transferred to the paper surface without dissolving the ink. In addition, in the cross-section preparation method according to the present invention, since the printing paper as the base material can be cut together with the ink transfer layer, the paper layer structure and the ink transfer layer can be observed at the same time. Therefore, the influence of the paper layer structure on the ink transfer is analyzed. Therefore, it was confirmed that it was a very effective method.

In the method of producing a cross section when the printed material is an intaglio printed material, the irradiation conditions of the ion beam used in the above embodiment are as follows: the gallium ion beam is accelerated at an acceleration voltage of 30 kV or more, the beam current is about 15 nA, and the beam diameter is 1000n
m, and rough processing is performed. Further, as finishing processing, at an acceleration voltage of 30 kV or more and a beam current of 1 nA or less,
A cross section can be formed by irradiating a beam with a beam diameter of 70 nm or less.

[0030]

As described above, the present invention has a thickness of several μm.
The FIB device used for local machining of
It was found that it was possible to cut out a cross section of paper or printed matter of about 0 μm, and the parameters of the accelerating voltage, beam current and beam diameter of the focused ion beam were set to the conditions for roughing and finishing using this apparatus. By irradiating, it is possible to produce a cross section of paper or printed matter with an accuracy that is incomparable with the conventional technology, and it has been repeatedly performed because the cross-sectional production position cannot be designated by the conventional cross-sectional production method It has become possible to significantly reduce the time and labor required for the cross-section preparation work and the observation. In addition, the acceleration voltage, beam current and beam diameter during roughing and finishing are set to specific values for composite materials and materials with voids, that is, materials with different hardness and brittleness, that is, paper or printed matter. However, by irradiating the focused ion beam in an amount necessary for producing a cross section of paper or printed matter, it is possible to produce a sharp cross section without causing processing damage (structural destruction) and temperature rise. It has become possible to fabricate a cross section without causing structural destruction or structural change caused by a conventional cross-section fabrication method. Furthermore, since the resin embedding process that was performed to prevent structural destruction during cross-section preparation is not required, it is possible to directly observe the cross-section of the ink layer that has been transferred to the paper surface of the printing ink that could not be observed until now. It became possible for the first time. In addition, since the printing paper, which is the base material, can be cut together with the ink transfer layer, the paper layer structure and the ink transfer layer can be observed at the same time. This is a very effective method for analyzing the effect of the paper layer structure on the ink transfer. . Thus, the method for preparing a cross section of the paper of the present invention is as follows.
This is particularly effective as a method for producing a cross section that replaces the conventional glass knife or steel knife method when analyzing the structure of paper.

[Brief description of the drawings]

FIG. 1A is an external view of a focused ion beam apparatus.
(B) is a schematic diagram of the inside of the device.

FIG. 2 is a secondary electron image photograph of a printed material before cutting out a cross section (× 200).

FIG. 3 is a secondary electron image photograph of a printed material after a cross section has been cut out by the production method of the present invention (× 200).

FIG. 4 is an electron micrograph (× 800) of a cross section of a sheet cut out by the manufacturing method of the present invention.

FIG. 5 is an electron micrograph (× 300) of a cross section of a sheet cut with a sharp blade according to a conventional method.

FIG. 6 (a) is an electron micrograph (× 800) of a cross section of double coated paper cut out by the production method of the present invention,
(B) is an electron micrograph (× 3000) of an enlarged portion of the coating layer in the cross section of the double coated paper.

FIG. 7 is an electron micrograph (× 700) of a cross section of double coated paper cut out with a sharp blade by a conventional method.

FIG. 8 is an electron micrograph (5000 times) of a cross section of a gravure print cut out by the production method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid gallium ion 2 Focusing lens part 3 Sample insertion port 4 Monitor 5 Operation part 6Beam limiting aperture  7 Deflector 8 Objective Lens 9 Secondary Electron Detector 10 Paper or Printed Material 11 Sample Holder 12 Ion 13 Cross Section of Printed Paper 14 Paper Surface of Printed Material 15 Ink Transfer Portion Printed on Paper Surface of Printed Material 16 In Paper Layer Fiber portion 17 Void portion in paper layer 18 Fiber portion in paper layer 19 Void portion in paper layer 20 Fiber as base material of double coated paper 21 Void portion in paper layer of double coated paper 22 Internally added Filler 23 Top coated layer of double coated paper 24 Under coated layer of double coated paper 25 Fiber which is the base material of double coated paper 26 Void portion in paper layer of double coated paper 27 double coated paper Coating layer 28 Ink transfer printed on the surface of gravure printed paper
Transferred part 29 Coating layer of gravure printing paper 30 Fiber serving as the base material of gravure printing paper A Printed material not subjected to resin embedding or other pretreatment B Paper not subjected to resin embedding treatment C Not subjected to resin embedding treatment Double coated paper D Gravure print without resin embedding x Cutting line y Cutting area

Continuation of the front page (51) Int.Cl. ⁷ identification code FI G01N 1/28 G01N 33/34 33/34 1/28 G (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 15/00 -15/08 B26F 3/16 G01N 1/28 G01N 33/34

Claims (2)

(57) [Claims] 1. A focused ion beam apparatus for performing local processing, comprising: an ion beam irradiation unit, an image detection unit, a cross-section processing condition setting unit, and an observation unit. From the ion beam irradiating means of the focused ion beam device, irradiating an ion beam, and by irradiating the secondary electron image detected by the image detecting means, while observing by the observing means, the cutout area of the paper or printed matter and specifies the cut-out position, then the acceleration voltage of the focused ion beam by the cross section processing condition setting means, the beam current, roughing the cross-section processing conditions of the beam diameter, specifications
Setting the conditions of the lifting process, and irradiating an ion beam of an amount necessary for cutting the cutout region and the cutout position, thereby forming a cross section at the cutout position. Law. 2. The method according to claim 1, wherein the ion beam is gallium.