CN107407056A - wrapping paper - Google Patents

Abstract

The invention provides a packaging paper which generates contrast between a watermark part and a non-watermark part when facing light, the watermark part is clearly visible, the design is excellent, and the buffer property is also excellent. The packaging paper of the present invention is obtained by mixing natural pulp and olefin-based synthetic pulp and making paper, and has a watermark portion having a higher light transmittance than that of the peripheral portion, and the watermark portion is free of pulp or has less pulp than that of the peripheral portion. The weight per unit area of the packaging paper of the present invention is preferably 30g/m²The following. The packaging paper of the present invention is produced by a step of forming a wet paper web by papermaking of both pulps from a dispersion of natural pulp and synthetic pulp and then drying the wet paper web, and the wet paper web before drying has a portion where no pulp or less pulp than the peripheral portion is present.

Description

wrapping paper

technical field

The present invention relates to packaging paper, and specifically relates to packaging paper formed of white watermarked design paper.

Background technique

Design paper on which a watermark pattern is applied is widely used in fields such as packaging, decoration, and printing due to its appearance characteristics. The watermark pattern applied on the paper has a "white watermark" in which the pattern part is visible and a "black watermark" in which the pattern part is darker than the surrounding and is visible. These watermark patterns are usually formed by partially changing the basis weight of pulp in the wet paper formation stage (paper machine wire section) in the papermaking process. In the paper machine wire section, when using a papermaking wire with a pattern of a punch, the part of the wet paper corresponding to the pattern of the punch is molded with a thickness thinner than the peripheral part, and the pressed part becomes The white watermark in the paper obtained by drying this wet paper. In addition, as other methods of forming white watermarks, there are also known press means such as press rollers that press a pattern of a punch on the outer surface of wet paper (wet paper with a uniform pulp basis weight) formed on the wire section of a paper machine. The outer surface, so that the pattern is transferred to the wet paper to form the method.

Patent Document 1 discloses anti-counterfeiting paper with a white watermark. The anti-counterfeit paper with white watermark is obtained by heat-pressing the paper obtained by mixing papermaking of natural pulp and polyolefin-based fibers after papermaking. Olefin fibers are softened and melted.

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2005-330622

Contents of the invention

The problem to be solved by the invention

The present invention relates to a packaging paper having a contrast between a watermark portion and a non-watermark portion when exposed to light, the watermark portion is clearly visible, excellent in design, and excellent in cushioning properties.

means to solve the problem

The packaging paper of the present invention is a packaging paper obtained by mixing natural pulp and olefin-based synthetic pulp, and has a watermark portion having a higher light transmittance than the peripheral portion, and the watermark portion does not have pulp or has less pulp than the peripheral portion .

Moreover, the manufacturing method of the packaging paper of this invention is the manufacturing method of the said packaging paper of this invention, It comprises making both pulp from the dispersion liquid of the said natural pulp and the said synthetic pulp to form wet paper, and then making this wet paper In the drying step, the wet paper before drying has a portion where there is no pulp or less pulp than the peripheral portion.

In the method for producing packaging paper according to the present invention, it is preferable that the "portion where there is no pulp or pulp is less than the peripheral portion" in the wet paper be formed by purposely blocking the portion to be formed of the watermark portion during the wet paper forming process. Formed by the accumulation of pulp in it.

Invention effect

According to the present invention, there is provided a packaging paper that produces a contrast between the watermarked portion and the non-watermarked portion when exposed to light, the watermarked portion is clearly visible, has excellent designability, and is also excellent in cushioning properties.

Description of drawings

In FIG. 1 , FIG. 1( a ) is a photograph of the packaging paper of Example 1, and FIG. 1( b ) is a photograph of the packaging paper of Comparative Example 1.

detailed description

The packaging paper of the present invention is obtained by mixing natural pulp and olefin-based synthetic pulp to produce paper. In the present invention, as natural pulp, wood bleached chemical pulps such as conifer bleached kraft pulp (NBKP), broadleaf bleached kraft pulp (LBKP), and conifer bleached sulfite pulp (NBSP) are mainly used, and groundwood pulp ( GP), thermomechanical pulp (TMP), chemical thermomechanical pulp (BCTMP) and other mechanical pulp; non-wood pulp such as hemp, bamboo, straw, kenaf, knotwood, mulberry, and cotton; waste paper pulp. In this invention, these natural pulps can be used individually by 1 type or in combination of 2 or more types.

The Canadian standard freeness (Canadian Standard freeness) stipulated in JIS P8121 of the natural pulp used in the present invention is preferably 100 to 500 ml, more preferably 250 to 400 ml. Freeness is a value indicating the degree of pulp beating (mechanical beating and grinding of pulp in the presence of water). Usually, the smaller the value of freeness, the stronger the degree of beating, and the greater the damage of beating to fibers. Filamentation proceeds. When the freeness of the natural pulp is within the above range, the balance of various properties such as a reduction in the basis weight of the packaging paper and an improvement in liquid permeability becomes good. Adjustment of freeness, that is, adjustment of pulp beating degree can be performed by appropriately adjusting the type of beating device and processing conditions (pulp concentration, temperature, pressure, rotation speed, shape of blade, number of processing, etc.). As the beating device, known devices can be used. For example, in addition to beating machines such as a beating machine, a PFI mill, a single-disk mill, and a double-disk mill, a ball mill used for dispersing and pulverizing pigments, etc., and DYNO can also be used. -Dispersing machines such as MILL.

Examples of the olefin-based resin constituting the olefin-based synthetic pulp used in the present invention include polyethylene, polypropylene, and the like.

The olefin-based synthetic pulp used in the present invention is preferably fibrillated like natural pulp from the viewpoint of securing practically sufficient paper strength. Fibrillation of olefin-based synthetic pulp can be performed by the same method as fibrillation of natural pulp. The freeness of the olefin-based synthetic pulp used in the present invention is preferably 100 to 700 ml, more preferably 300 to 600 ml.

Mitsui Chemicals, Inc. SWP (registered trademark) is mentioned as a commercially available olefin-based synthetic pulp preferably used in this invention. This SWP is a fibrillated olefin-based synthetic pulp.

In addition, the fiber length of the olefin-based synthetic pulp used in the present invention is preferably 0.1 to 2.0 mm, more preferably 0.5 to 1.5 mm. When the fiber length of the olefin-based synthetic pulp is within this range, water drainage is improved in the paper machine wire section in the papermaking process when packaging paper is produced by the wet papermaking method, and watermarks are easily formed.

The packaging paper of the present invention may contain other components other than natural pulp and olefin-based synthetic pulp as required, such as paper strength enhancers such as starch, polyacrylamide, polyamine polyamide epichlorohydrin, or fixing agents, sizing agents, etc. One or more of the additives commonly used in the wet papermaking process, such as additives, fillers, drainage and retention aids, water-resistant agents, fixing agents, defoamers, and slimeicides.

The packaging paper of the present invention has a watermark portion having a higher light transmittance than the peripheral portion. The watermark portion of the present invention is a portion where there is no pulp or less pulp than the peripheral portion (non-watermark portion), in other words, it is a through hole that penetrates the packaging paper in the thickness direction or the amount of pulp accumulated is lower than that of the peripheral portion (non-watermark portion). The few low-pulp accumulation parts are so-called white watermarks that are brighter and transparent than the peripheral parts when viewed under transmitted light. In the wrapping paper of the present invention, the plan view shape, size, number, pattern, etc. of the watermark portion are not particularly limited, and may be appropriately adjusted according to applications. An example of the wrapping paper of the present invention includes a form in which a plurality of watermark portions are formed in a predetermined pattern, and each watermark portion is surrounded by a non-watermark portion. The watermark portion may be only a through hole, or only a low pulp accumulation portion, or both. As an example of this case, a through hole that penetrates the packaging paper in the thickness direction, and a The watermark part is composed of a low pulp accumulation part with a through hole and less pulp accumulation than the peripheral part. On the other hand, the non-watermarked portion, which is the peripheral portion of the watermarked portion, is a high pulp accumulation portion having a larger amount of pulp accumulation than the watermarked portion, and is a portion that does not transmit light or has a light transmittance lower than that of the watermarked portion.

According to the knowledge of the present inventors, compared with normal paper containing natural pulp but not containing olefin-based synthetic pulp, the white-watermarked paper containing natural pulp and olefin-based synthetic pulp has a watermark portion that is different from that of non-olefin-based synthetic pulp when exposed to light. Since the contrast of the watermark is more conspicuous, the observer can have the impression that the watermark is floating, so the watermark is clear and has high designability. That is, olefin-based synthetic pulp exhibits the effect of increasing the opacity of paper and making white watermarks visible. In addition, in general, olefin-based synthetic pulp has shorter fiber length and better drainage than natural pulp. In the wire part of the paper machine in the papermaking process, through holes or low pulp accumulation parts can be easily formed on the wet paper, so there is also an advantage that the formation of the watermark part is easy. The wrapping paper of the present invention is an invention based on such knowledge.

The opacity [opacity of the portion other than the watermark portion (non-watermark portion)] specified in JIS P8149 of the packaging paper of the present invention is preferably 35 to 80%, more preferably 40 to 65%. The opacity of packaging paper can be adjusted by appropriately adjusting the type and content of olefin-based synthetic pulp.

In addition, as another function and effect of olefin-based synthetic pulp, there is an effect of improving cushioning properties. That is, the packaging paper of the present invention comprising natural pulp and olefin-based synthetic pulp has the characteristics of low density and high cushioning properties compared to ordinary paper comprising natural pulp but not olefin-based synthetic pulp, and thus is suitable for making full use of It is used for packaging of cushioning items.

The density of the packaging paper of the present invention is preferably 0.2 to 0.6 g/cm ³ , more preferably 0.3 to 0.5 g/cm ³ . In addition, when the packaging paper of the present invention is produced by the method of 1) or 2) described later (the method of forming through-holes or low-pulp accumulation parts in the wet paper before drying), that is, the "no pulp" in the wet paper Pulp is present or a portion with less pulp than the peripheral portion" (a portion of wet paper that becomes a watermark after drying) is formed by deliberately inhibiting the accumulation of pulp in a portion to be formed of a watermark in the wet paper forming process , the density of the watermark portion in the packaging paper thus obtained is the same as or lower than that of the surrounding non-watermark portion. In contrast, the watermark portion (white watermark) in the paper described in Patent Document 1 is formed by softening and melting polyolefin-based fibers through hot-press treatment in the external processing after papermaking, so it is presumed that its density is higher than that of the surrounding non-watermark. department high.

In addition, in the paper described in Patent Document 1, the watermark portion is formed by subjecting a part of the paper having a uniform basis weight of the pulp to a heat press treatment. Due to its manufacturing method, the watermark portion formed by the heat press treatment and its surrounding areas are not subjected to heat press treatment. There was no substantial change in the amount of pulp in the non-watermarked portion. In this regard, the watermark portion of the present invention is a portion where there is no pulp or less pulp than the peripheral portion (non-watermark portion) as described above. And they are all different in terms of the amount of pulp. Such a watermark with a relatively small amount of pulp cannot be formed by hot pressing of paper, but as described later, it can be formed by deliberately preventing the accumulation of pulp in the part where the watermark is to be formed in the wet paper forming process. form.

In addition, as described in Patent Document 1, the watermark formed by hot-pressing treatment also depends on the conditions of the hot-pressing treatment, but usually the olefin-based synthetic pulp melts and softens under the hot-pressing treatment, so the fiber shape cannot be maintained, and the surrounding Compared with the non-watermarked part that has not been subjected to hot pressing treatment, the interfiber voids are smaller, and in some cases the interfiber voids almost completely disappear, and may be in a film-like film-like form. In this regard, the fiber shape of the watermarked portion of the present invention that has not been subjected to hot-pressing treatment is maintained, and there is no substantial difference in the shape of the fiber assembly compared with the non-watermarked portion of the peripheral portion.

The cushioning properties of the packaging paper can be evaluated by the compressive strength of the packaging paper, and the larger the numerical value of the compressive strength, the higher the evaluation of the cushioning properties of the packaging paper. However, when the numerical value of the compressive strength is too large, since the rigidity of the packaging paper increases, it is difficult for the packaging paper to follow the shape of the object to be packaged, and there is a possibility that the function as the packaging paper may be reduced. In consideration of the above, the compressive strength of the wrapping paper of the present invention is preferably 0.2 to 0.9, more preferably 0.4 to 0.6. The compressive strength (cushioning property) of packaging paper can be adjusted by appropriately adjusting the type and content of olefin-based synthetic pulp. In addition, in order to adjust the compressive strength of the packaging paper to the above-mentioned range, as described later, in the papermaking process when the packaging paper is produced by the wet papermaking method, it is preferable to dry the paper obtained by drying the wet paper (packaging paper) without pressing.

The "compression hardness of the packaging paper" was measured using a known KES compression tester, and the compression strength of the packaging paper was calculated by subtracting the measured value from 1. That is, "compression strength=1-compression hardness", the larger the numerical value of the compression hardness, the lower the compression strength (cushioning property) of the packaging paper is evaluated. The compression hardness measurement method using the KES compression tester is a method of measuring the stress when the measurement object (packaging paper) is compressed with a circular plane (2cm ² ). The compression hardness is expressed by the linearity of compression. The closer the value is to 1 means that the measured object is harder.

The method of measuring the compressive strength will be described more specifically. The KES compression testing machine used in the measurement is equipped with a metal pressure element with an area of 2 cm ² in contact with the measurement object. As a KES compression testing machine configured in this way, for example, a disc-shaped metal pressure element is provided. The brand name "KES-G5" manufactured by Kato Tech Co., Ltd. Fix the measurement object (packaging paper) on the sample mounting table of the KES compression testing machine, press the pressure member from above the measurement object at a predetermined speed into the thickness direction of the measurement object with a predetermined pressure, and measure The maximum stress at this time. The pressing speed of the presser is 0.0067-0.02mm/sec, and the pressing pressure is within the range of 50-500gf/cm ² . The measurement of the maximum stress is carried out at any three places in each area of the measurement object with an area of 100 cm ² , and the average value of a plurality of measured values obtained in this way is regarded as the compression hardness of the measurement object, and the compressive strength of the measurement object is calculated by the following formula.

Compressive strength = 1 - compressive hardness

Important properties of packaging paper such as cushioning properties (compressive strength) and paper strength are largely influenced by the pattern of the watermark portion of the packaging paper. That is, the compressive strength of the wrapping paper may vary depending on the planar shape, size, number, etc. of the watermark portions in the wrapping paper. In particular, packaging paper with a low basis weight of 30 ^g /m or less has a small absolute amount of pulp that has a positive effect on cushioning properties or paper strength, so the watermark portion in the packaging paper The effect of style on cushioning etc. cannot be ignored. Furthermore, the watermark portion of the present invention, as described above, is a portion where there is no pulp or less pulp than the peripheral portion (non-watermark portion). It is more preferable to partially exist in a discrete or scattered point form in the entire wrapping paper than to exist locally in the wrapping paper.

In the present invention, there is no particular limitation on the pattern of the watermark portion, and for example, the watermark portion may be a “shape not surrounded by a non-watermark portion” (non-closed shape) such as a continuous line from one end to the other end of the wrapping paper. A plurality of discrete forms, but in consideration of the important characteristics of packaging paper such as cushioning, it is preferable that "a plurality of watermarks are scattered in the entire packaging paper, and each watermark is surrounded by a non-watermark, that is, closed. Shape Style". The wrapping paper of each Example described later is a concrete representation of the pattern of the preferred watermark portion. The top view shape of each watermark portion is not particularly limited, and can be arbitrarily selected from a circle shape, an ellipse shape, a triangle shape, a polygon shape larger than a quadrilateral, a straight line or a curve, etc., and two or more different top view shapes can also be used. combination.

The area of one watermark portion in the packaging paper is preferably 1.5 cm ² or less, more preferably 0.01 to 1.0 cm ² , from the viewpoint of reliably satisfying important properties of packaging paper such as cushioning properties.

From the same viewpoint, when the area of one watermark is within the above preferred range, the number of watermarks per 100 cm ² area of the packaging paper is preferably 5 or more, more preferably 10 to 600.

From the same viewpoint, the distance between the centers of adjacent watermarks (the pitch of the watermarks) is preferably 1 to 50 mm, more preferably 3 to 30 mm.

In addition, from the viewpoint of more reliably exerting the effect of the above-mentioned olefin-based synthetic pulp, the content of the olefin-based synthetic pulp in the packaging paper of the present invention is 100 parts by mass of the natural pulp in the packaging paper, Preferably it is 1-70 mass parts, More preferably, it is 5-40 mass parts. When the content of olefin-based synthetic pulp is too small relative to natural pulp, there is a concern that the effect of the above-mentioned olefin-based synthetic pulp cannot be sufficiently obtained. When the content of olefin-based synthetic pulp is too large relative to natural pulp, the sheet strength may be reduced Weak and unable to obtain the strength required as wrapping paper.

The packaging paper of the present invention can be produced by a known wet papermaking method, specifically, through the following steps: using a papermaking wire to draw out both pulps from a dispersion of natural pulp and synthetic pulp to form wet paper, and then Wet paper to dry. The above-mentioned watermark portion, that is, the through hole through which the packaging paper penetrates in the thickness direction, or the low pulp accumulation portion in which the amount of pulp accumulation is smaller than that of the peripheral portion can be obtained by pressing a roller with a concave-convex pattern on the outer surface of the paper obtained by drying the wet paper. The outer surface is shaped, and the concave-convex pattern is transferred to the paper and shaped (dry press pattern method). There is a concern that the effect of cushioning improvement is reduced. Therefore, from the viewpoint of reliably obtaining packaging paper excellent in cushioning properties, it is preferable to form a portion (through-hole or low-pulp accumulation portion) where no pulp exists or less pulp than the peripheral portion on the wet paper before drying. The through-holes and low-pulp accumulation portions formed in the wet paper serve as watermarks (white watermarks) in paper (packaging paper) obtained by drying the wet paper.

As a method of forming through-holes or low-pulp accumulation parts in wet paper (a method of suppressing the decrease in the effect of improving cushioning properties by olefin-based synthetic pulp), for example, 1) combining with through-holes or low-pulp accumulation parts The papermaking wire with the concave and convex part corresponding to the part (watermark part in packaging paper), or the papermaking wire with the through hole or the low pulp accumulation part and plug the mesh with resin, etc. is used as the cylinder of the cylinder paper machine The watermarking roll of the cylinder or fourdrinier paper machine, etc., the method of copying the two pulps from the dispersion liquid of natural pulp and synthetic pulp to form wet paper, 2) using the fourdrinier wire from the dispersion liquid of natural pulp and synthetic pulp Rolls (press rolls, suction rolls, etc.) having concave and convex portions on the outer surface corresponding to through holes or low pulp accumulation portions for wet paper formed by paper machine wires of known paper machines such as paper machines and cylinder paper machines. The method of pressing the outer surface. In the method of 2) above, since the wet paper is partially pressed, there is a concern that the cushioning properties of the pressed portion in the packaging paper obtained by drying it may be reduced. Therefore, it is preferable to reduce the pressure when pressing the wet paper as much as possible ( Line pressure of pressing means such as pressure roller). In contrast, the method of 1) above, that is, the method of partially inhibiting or restricting the accumulation of pulp during wet paper formation, and the method of forming wet paper with through holes or low pulp accumulation parts formed in advance, has no risk of reducing cushioning properties, so it is used in It is preferably used in the present invention.

The weight per unit area of the packaging paper of the present invention is not particularly limited, and the packaging paper of the present invention has "a low basis weight, as a result, even if the opacity of the packaging paper is reduced, the watermark and The contrast of the non-watermarked part is obvious, and the watermarked part is clearly visible". Therefore, from the viewpoint of fully utilizing this feature, a lower basis weight is preferred. Specifically, it is preferably 30 g/ ^m2 or less, and more preferably 10 to 10 g/m2. 25g/m ² .

The packaging paper of the present invention may be colored in any color, and may have a single-layer structure or a multi-layer structure in which multiple layers are laminated. In the case of a multilayer structure, it is preferable that each layer is laminated and integrated. In addition, in the case of a multi-layer structure, the watermark portion may be formed in all or only a part of the layers, and the watermark portion in one layer may overlap with the watermark portion in another layer in plan view.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Example 1]

NBKP was used as natural pulp. NBKP was beaten with a double-disk refiner until the Canadian standard freeness reached 400 ml, and 40 parts by mass of olefin-based synthetic pulp (SWP (registered trademark) manufactured by Mitsui Chemicals, Inc., product name "E620") was added to 100 parts by mass of NBKP. copies, prepare paper stock. Using this paper stock, according to the method of above-mentioned 1) with cylinder paper machine, obtain the packaging paper with unit area weight of 17g/m ² single-layer structure and no coloring. In the obtained packaging paper, as shown in FIG. 1( a ), a large number of scattered watermarks were formed with no pulp or less pulp than the peripheral portion. More specifically, the closed-shaped watermark portion surrounded by the non-watermark portion is in the form of scattered dots throughout the packaging paper, the area of one watermark portion is 0.04 cm ² , and the number of watermark portions per 100 cm ² area is The average pitch between 311 adjacent watermark portions is 7 mm.

[Example 2]

Except for adding 5 parts by mass of olefin-based synthetic pulp to 100 parts by mass of NBKP, it was carried out in the same manner as in Example 1 to obtain a packaging paper with a single-layer structure and no coloring having a basis weight of 17 g/m ² .

[Example 3]

Except for adding 10 parts by mass of olefin-based synthetic pulp to 100 parts by mass of NBKP, it was carried out in the same manner as in Example 1 to obtain a single-layer structure with a basis weight of 17 g/m ² and a non-colored packaging paper.

[Example 4]

Except for adding 20 parts by mass of olefin-based synthetic pulp to 100 parts by mass of NBKP, it was carried out in the same manner as in Example 1 to obtain a single-layer structure with a basis weight of 17 g/m ² and an uncolored packaging paper.

[Example 5]

Except that the weight per unit area was 30 g/m ² , it was carried out in the same manner as in Example 1 to obtain a packaging paper with a single-layer structure and no coloring.

[Comparative Example 1]

Except not using olefin-based synthetic pulp, it was carried out in the same manner as in Example 1 to obtain a single-layer packaging paper with a basis weight of 17 g/m ² and no coloring.

[Comparative Example 2]

The watermark portion was formed in accordance with the method of Patent Document 1, that is, by applying hot pressing to paper obtained by drying wet paper in a predetermined pattern, except that it was performed in the same manner as in Example 1 to obtain the basis weight It is a 17g/m ² single-layer structure and non-colored packaging paper. More specifically, using the same paper stock as in Example 1, paper with a uniform weight per unit area was produced by a cylinder paper machine, and the paper was heated in the same pattern as the watermark part in Example 1. The heating temperature was 140 ° C. The watermark portion was formed by hot pressing with a heating time of 4 seconds. The watermarked portion formed by hot-pressing treatment has an olefin-based synthetic pulp that is melted and softened under hot-pressing treatment, so there is no substantial difference in the amount of pulp compared with the surrounding non-watermarked part, but the density is high and the fiber shape failed to maintain.

The opacity and compressive strength of the packaging papers of the respective examples and comparative examples were evaluated according to the above-mentioned methods. The results are shown in Table 1 below.

Table 1

As shown in Table 1, since the packaging paper of each example contains olefin-based synthetic pulp in addition to natural pulp, the opacity of the non-watermarked part is lower than that of the packaging paper of Comparative Example 1 that does not contain olefin-based synthetic pulp. High compressive strength, that is, high cushioning. As mentioned above, when the opacity of the non-watermark part is high, the contrast between the watermark part and the non-watermark part becomes obvious when the packaging paper faces the light, so the visual effect of the watermark part floating is exerted, and the watermark part is clearly visible , Improved design. In fact, as shown in FIG. 1, the packaging paper of Example 1 (see FIG. 1(a)) compared with the packaging paper of Comparative Example 1 (see FIG. 1(b)), the watermark portion and the non-watermark portion The contrast is obvious, and the watermark is clearly visible.

As can be seen from the above, in order to obtain packaging paper with a watermark portion excellent in designability and cushioning properties, it is effective to make paper by mixing natural pulp and olefin-based synthetic pulp.

In addition, Comparative Example 2 is different from Example 1 in that the watermark portion is formed by thermal pressing. ) is substantially the same amount of pulp, which is different from the configuration of Example 1 in which there is no pulp in the watermark portion or less pulp than in the peripheral portion. In addition, Comparative Example 2 is different from the configuration of Example 1 in which the fiber form of the watermark is maintained and the fiber form is substantially the same as that of the non-watermark, since the watermark is heat-pressed, so the fiber form cannot be maintained. Furthermore, although the pattern of the watermark portion is the same between Example 1 and Comparative Example 2, as shown in Table 1, there is a significant difference in compressive strength, which is the result that Example 1 is more excellent in cushioning properties.

From the above, in order to obtain a watermarked packaging paper with high cushioning properties, it is preferable that there is no or less pulp in the watermarked portion than in the peripheral portion (non-watermarked portion), or that the watermarked portion maintains a fibrous form.

Claims (4)

1. A packaging paper obtained by mixing natural pulp and olefin-based synthetic pulp, which has a watermark portion with a higher light transmittance than the peripheral portion, and the watermark portion does not contain pulp or pulp Less than the peripheral part. 2. The wrapping paper according to claim 1, which has a basis weight of 30 g/m ² or less. 3. The packaging paper according to claim 1 or 2, wherein the compressive strength measured by the following method is 0.2 to 0.9, The method of measuring the compressive strength: using a metal presser with an area of 2 ^cm2 in contact with the measurement object, press the presser with a predetermined pressure in the direction of the thickness of the measurement object at a predetermined speed, Measure the maximum value of the stress at this time; make the indentation speed of the presser in the range of 0.0067-0.02mm/second, and the indentation pressure in the range of 50-500gf/ ^{cm2 ;} for each area of the measurement object with an area of 100cm2 The measurement of the maximum stress is carried out at any three places, and the average value of the plurality of measured values obtained in this way is regarded as the compressive hardness of the measurement object, and the compressive strength of the measurement object is calculated by the following formula, Compressive Strength = 1 - Compressive Hardness. 4. The method for producing packaging paper according to any one of claims 1 to 3, comprising the steps of drawing out both pulps from a dispersion liquid of the natural pulp and the synthetic pulp to form wet paper, and then making the wet paper In the step of drying the paper, a portion where pulp is absent or less than the peripheral portion is formed in the wet paper before drying.