Paper base for cushioning materials and paper cushioning materials

Abstract

The present invention provides a base paper for cushioning material that allows for the formation of multiple convex shapes, resulting in a paper cushioning material that is easy to create convex shapes on, less prone to tearing of the convex shapes, and has excellent cushioning properties, and a paper cushioning material having multiple convex shapes formed on one or both sides of the surface of the base paper for cushioning material. [Solution] Add multiple protrusions (70 per 100cm) to one or both sides of the paper surface. 2 A base paper for cushioning material, formed as described above, wherein the fiber orientation strength is 1.00 or more and 1.45 or less, and the synergistic mean of the Clark stiffness in the longitudinal direction and the Clark stiffness in the transverse direction is 33 or more and 70 or less. A plurality of protrusions of 70 per 100 cm are formed on one or both sides of the surface of the cushioning material base paper. 2 A paper cushioning material formed as described above.

Description

[Technical Field]

[0001] This invention relates to base paper for cushioning materials and paper cushioning materials. [Background technology]

[0002] Cushioning materials are used to fill the gaps between the case and the contents when goods are stored in cases such as envelopes or cardboard boxes, and to absorb vibrations and shocks that occur to the contents during transportation. Traditionally, cushioning materials have been made from resins such as polyethylene or polyurethane foam.

[0003] In recent years, the problem of plastic waste has become increasingly serious worldwide, and in order to improve the global environment, the elimination and reduction of plastic in packaging materials is being promoted, and there is a growing movement to replace plastic packaging with paper packaging. From an environmental protection standpoint, paper-based cushioning materials are becoming more widespread as an alternative to plastic cushioning materials.

[0004] Patent Document 1 discloses a paper-based protective sheet that can improve portability, comprising kraft paper containing coniferous pulp, wherein the content of the coniferous pulp is 90% by mass or more and 95% by mass or less relative to the mass of the kraft paper, and the kraft paper has a thickness of a specific value or less and a basis weight within a specific range. Patent Document 2 discloses a cushioning packaging sheet and a packaging bag used when packaging articles, which protects articles, and the cushioning packaging sheet is an embossed paper having numerous uneven shapes over substantially the entire surface of the paper base, characterized in that the height of the uneven shapes is greater than the thickness of the paper base and is below a specific value. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-44936 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-177304 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] As one of the plastic cushioning materials, there is a bubble cushioning material in which a plurality of granular bubbles are arranged between film sheets such as polyethylene. However, it is also desired to make the material into paper for this bubble cushioning material. When forming a convex portion on paper to make a cushioning material like a plastic bubble cushioning material, the convex portion may be torn during the process of forming the convex portion. From the viewpoint of cushioning performance, it is desirable that a convex shape is easily formed, the tearing that occurs during the formation of the convex portion is reduced as much as possible, and on top of that, the cushioning performance of the cushioning material is improved.

[0007] The concave grooves of the curing sheet described in Patent Document 1 function as anti-slip when walking on the curing sheet. The cushioning packaging sheet described in Patent Document 2 has an uneven shape and is not an optimized base paper of the cushioning packaging sheet for imparting a convex shape to paper.

[0008] An object of the present invention is to provide a base paper for a cushioning material for forming a plurality of convex portions on one side or both sides of a paper surface, which can easily form a plurality of convex shapes when forming the convex portions, has few tears in the convex portions, and can be made into a paper cushioning material with excellent cushioning performance, and a paper cushioning material formed by forming a plurality of convex portions on one side or both sides of the paper surface of the base paper for the cushioning material. [Means for Solving the Problems]

[0009] The inventors of the present invention have found that by setting the fiber orientation strength of the base paper for the cushioning material within a specific range and setting the multiplicative average value of the Clark stiffness in the longitudinal direction and the Clark stiffness in the transverse direction of the base paper for the cushioning material within a specific range, the above problems can be solved. That is, the present invention has the following configuration. <1> A base paper for a cushioning material for forming a paper cushioning material by forming 70 or more convex portions per 100 cm on one or both sides of the paper surface , , , [Figure 1] ,

[0011] The base paper for a cushioning material is a base paper for a cushioning material for forming a paper cushioning material by forming 70 or more convex portions per 100 cm on one or both sides of the paper surface, having a fiber orientation strength of 1.00 or more and 1.45 or less, and a multiplicative average value of the Clark hardness in the longitudinal direction and the Clark hardness in the transverse direction of 33 or more and 70 or less. <2> The base paper for a cushioning material according to <1>, having a thickness of 110 μm or more and 160 μm or less. <3> The base paper for a cushioning material according to <1> or <2>, wherein the content of softwood pulp in the raw material pulp constituting the base paper for a cushioning material is 80% by mass or more. <4> The base paper for a cushioning material according to any one of <1> to <3>, having a multiplicative average value of the tensile elastic modulus in the longitudinal direction and the tensile elastic modulus in the transverse direction of 1.2 GPa or more and 3.5 GPa or less. <5> The basis weight is 70 g / m 2 or more and 110 g / m 2 or less. The base paper for a cushioning material according to any one of <1> to <4>. <6> A paper cushioning material formed by forming 70 or more convex portions per 100 cm on one or both sides of the paper surface of the base paper for a cushioning material according to any one of <1> to <5> 2 or more. <7> The volume per one of the plurality of convex portions is 20 mm 3 or more and 150 mm 3 or less. The paper cushioning material according to <6>.

Advantages of the Invention

[0010] According to the present invention, when forming convex portions by imparting a plurality of convex shapes, it is possible to achieve both the ease of forming the convex portion shape and the difficulty of breakage of the convex portion, and there are provided a base paper for a cushioning material that can be made into a paper cushioning material having excellent cushioning properties, and a paper cushioning material formed by forming a plurality of convex portions on one or both sides of the paper surface of the base paper for a cushioning material.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic diagram for explaining a configuration example of a paper cushioning material formed by forming a plurality of convex portions on one side of the paper surface of the base paper for a cushioning material of the present invention. [Figure 2] This is a schematic diagram illustrating an example of the structure of a paper cushioning material in which a plurality of protrusions are formed on both sides of the paper surface of the cushioning material base paper of the present invention. [Figure 3] Figure 1 is a cross-sectional view of the paper cushioning material shown as an example. [Figure 4] Figure 2 is a cross-sectional view of the paper cushioning material shown as an example. [Figure 5] This is a plan view showing the paper cushioning material according to the embodiment. [Figure 6] Figure 5 is a cross-sectional view of the paper cushioning material. [Modes for carrying out the invention]

[0012] [Base paper for cushioning material] The cushioning paper according to this embodiment (hereinafter also simply referred to as cushioning paper) has multiple protrusions on one or both sides of the paper surface, with 70 protrusions per 100 cm². 2 The cushioning paper of the present invention is a base paper for forming a paper cushioning material, wherein the fiber orientation strength is 1.00 or more and 1.45 or less, and the synergistic mean of the Clark stiffness in the longitudinal direction and the Clark stiffness in the transverse direction is 33 or more and 70 or less. In this specification, the numerical range expressed as "X~Y" means a numerical range that includes X as the lower limit and Y as the upper limit. When the numerical range is described in steps, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, the cushioning paper of the present invention may have any combination of the characteristics or physical properties described in this specification. The longitudinal direction of the cushioning paper means the papermaking direction (MD), and the transverse direction means the direction perpendicular to the papermaking direction (CD).

[0013] In this embodiment, the base paper for cushioning material has a fiber orientation strength below a specific value, resulting in high isotropy in strength and elongation, and reducing tearing of the convex parts when multiple convex shapes are added to form the convex parts. In this embodiment, the base paper for cushioning material has a synergistic mean value of the Clark stiffness in the vertical and horizontal directions that is above a specific value. As a result, the shape of the protrusions in the paper cushioning material, which has multiple protrusions formed on it, is easily restored after being subjected to a load, and as a result, the cushioning performance is easily maintained. Furthermore, if the synergistic mean value of the Clark stiffness in the vertical and horizontal directions is below a specific value, the protrusions are more easily formed when multiple protrusions are created. In this embodiment, the base paper for the cushioning material has multiple protrusions at 100 cm 2 A paper cushioning material formed with a certain number or more protrusions per surface area is designed to easily absorb the load when a load is applied to the paper cushioning material, and as a result, it has excellent cushioning properties.

[0014] The cushioning paper of this embodiment includes at least a paper substrate, and the paper substrate includes pulp as a raw material. The manufacturing method and type of pulp are not particularly limited. The cushioning paper of this embodiment may have a coating layer such as a resin layer or a laminate layer on the paper substrate, but it is preferable that it consists only of a paper substrate. The paper substrate may be a single-layer structure or a multi-layer structure, but a single-layer structure is preferred. In the case of a multi-layer structure, the number of paper layers is not particularly limited, but for example, it is preferably 2 to 7 layers, and more preferably 2 to 6 layers.

[0015] <Raw pulp> In this embodiment, natural pulp fibers are preferred as the raw material pulp constituting the cushioning paper (paper base material) from the viewpoint of reducing environmental impact. As natural pulp fibers, wood fibers (chemical pulp, mechanical pulp), non-wood fibers, deinked pulp (DIP, recycled paper pulp), etc., can be used as needed. Examples of chemical pulp include kraft pulp, which uses caustic soda and sodium sulfide when pulping wood chips, and sulfite pulp, which uses sulfurous acid and bisulfite. These pulps may be unbleached or bleached. Examples of mechanical pulp include ground wood pulp (GP) obtained by grinding logs with a grinder, refined ground wood pulp (RGP) obtained by grinding (refining) waste wood from sawmills with a refiner, and thermomechanical pulp (TMP) obtained by heating and refining wood chips. These pulp fibers can be used alone or in combination of two or more types. Furthermore, synthetic resin fibers may be incorporated as needed, to the extent that they do not impair the effects of the present invention. Examples of coniferous trees used as raw materials for wood fiber pulp include pine, larch, cedar, fir, and cypress. Examples of hardwoods used as raw materials for hardwood pulp include eucalyptus, acacia, birch, beech, maple, elm, and chestnut. Examples of non-wood fibers include bast fibers such as paper mulberry, mitsumata, gampi, flax, taima, kenaf, choma, jute, and sun hemp; seed hair fibers such as cotton and cotton linter; leaf fibers such as Manila hemp, sisal hemp, and esparto; and stem fibers such as bamboo, rice straw, wheat straw, and sugarcane bagasse. Non-wood fibers can be pulverized in the same way as wood fibers. Examples of deinked pulp include those made from recycled paper such as corrugated cardboard and magazine paper. Examples of synthetic resin fibers include polyethylene fibers, polypropylene fibers, polyamide fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, and polylactic acid fibers.

[0016] The raw material pulp preferably contains at least one selected from the group consisting of softwood pulp and hardwood pulp, more preferably contains at least one selected from the group consisting of softwood kraft pulp and hardwood kraft pulp, even more preferably contains at least one selected from the group consisting of unbleached softwood kraft pulp (NUKP) and unbleached hardwood kraft pulp (LUKP), and even more preferably contains at least one selected from the group consisting of unbleached softwood kraft pulp and unbleached hardwood kraft pulp.

[0017] The content of softwood pulp (preferably NUKP) in the raw pulp is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and 100% by mass or less, from the viewpoint of producing a paper cushioning material that is less prone to tearing of the protrusions when forming multiple protrusions on the base paper for cushioning material and has superior cushioning properties. The content of hardwood pulp (preferably LUKP) in the raw pulp is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and may even be 0% by mass, from the viewpoint of producing a paper cushioning material that is less prone to tearing of the protrusions when forming multiple protrusions on the base paper for cushioning material and has superior cushioning properties. When the raw pulp contains softwood pulp (preferably NUKP) and hardwood pulp (preferably LUKP), from the viewpoint of improving Clark stiffness and tensile modulus, the total content of softwood pulp (preferably NUKP) and hardwood pulp (preferably LUKP) in the raw pulp is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 93% by mass or more, and 100% by mass or less. The raw pulp may contain deinked pulp (recycled paper pulp), but from the viewpoint of improving Clark stiffness and tensile modulus, the content of deinked pulp (recycled paper pulp) in the raw pulp is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 7% by mass or less, and may even be 0% by mass.

[0018] From the viewpoint of obtaining appropriate paper strength for use as a base paper for cushioning material, the Canadian standard filtration efficiency (CSF) of the raw pulp is preferably 300 mL or more, more preferably 400 mL or more, even more preferably 450 mL or more, even more preferably 500 mL or more, and even more preferably 530 mL or more, and preferably 700 mL or less, more preferably 650 mL or less, even more preferably 600 mL or less, and even more preferably 580 mL or less. The CSF of the raw pulp is measured according to JIS P 8121-2:2012 "Pulp - Test methods for hydrophilicity - Part 2: Canadian standard hydrophilicity method".

[0019] (optional ingredient) The raw pulp may contain optional components as needed, such as pH adjusters (sodium bicarbonate, sodium hydroxide, etc.), dry strength enhancers, wet strength enhancers, internal sizing agents, filtration yield enhancers, defoamers, fillers (calcium carbonate, talc, etc.), dyes, and fixatives (aluminum sulfate). These optional components may be used individually or in combination of two or more. The content of these optional components is not particularly limited and may be within the range commonly used.

[0020] Examples of dry strength enhancers include polyacrylamide (PAM)-based dry strength enhancers, starch-based dry strength enhancers, CMC (carboxymethylcellulose) or its salts. These can be used individually or in combination of two or more. Among these, the dry strength enhancer preferably contains at least one selected from the group consisting of PAM-based dry strength enhancers and starch-based dry strength enhancers, and more preferably at least one selected from the group consisting of PAM-based dry strength enhancers and starch-based dry strength enhancers. When the base paper (paper substrate) for cushioning material has a multilayer structure, the drying strength enhancer may be contained in some of the layers, but it is preferable that it is contained in each layer, and it is even more preferable that the amount of the enhancer in each layer is within the range of the following preferred amounts. When a dry paper strength enhancer is included, the amount of the dry paper strength enhancer is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, and preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.0 part by mass or less, based on 100 parts by mass (in terms of solid content) of raw pulp.

[0021] Examples of wet-strength enhancers include polyamide polyamine epichlorohydrin resin (PAE), melamine-formaldehyde resin, and urea-formaldehyde resin. When the paper substrate has a multilayer structure, the wet strength enhancer may be contained in some of the layers, but it is preferable that it is contained in each layer, and it is even more preferable that the amount of each layer contains it is within the range of the following preferred amounts. When a wet-strength enhancer is included, the amount of the wet-strength enhancer is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and preferably 1.0 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less, per 100 parts by mass (in terms of solid content) of raw pulp.

[0022] Examples of internal sizing agents include rosin-based sizing agents and alkyl ketene dimers, with rosin-based sizing agents being preferred among these. Rosin-based sizing agents can include, for example, acidic rosin-based sizing agents, weakly acidic rosin-based sizing agents, and neutral rosin-based sizing agents. When the paper substrate has multiple layers, the internal sizing agent may be contained in some of the layers, but it is preferable that it is contained in each layer, and it is even more preferable that the amount of each layer is within the range of the following preferred amounts. When an internal sizing agent is included, the amount of the internal sizing agent is preferably 0.01 parts by mass or more and 3.0 parts by mass or less, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and even more preferably 1.0 part by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of raw pulp (in terms of solid content).

[0023] <Method for manufacturing base paper for cushioning material> The method for manufacturing the base paper for cushioning material preferably includes a step of papermaking a slurry containing the above-mentioned raw material pulp. The papermaking method is not particularly limited, and examples include an acidic papermaking method in which papermaking is performed at a pH of around 4.5, and a neutral papermaking method in which papermaking is performed at a pH of approximately 6 to approximately 9. In the papermaking process, chemicals for the papermaking process, such as pH adjusters, defoamers, pitch control agents, and slime control agents, can be added as needed. The papermaking machine is also not particularly limited, and examples include continuous papermaking machines such as twin-wire type, long-wire type, cylinder-wire type, and inclined type, or multi-layer papermaking machines that combine these. In the papermaking process, the jet / wire ratio (J / W ratio), which is the ratio of the flow velocity (J) of the paper pulp ejected onto the wire to the papermaking wire running speed (W), is preferably 1.30 or less, more preferably 1.20 or less, even more preferably 1.10 or less, even more preferably 1.05 or less, even more preferably 1.03 or less, and preferably 0.98 or more, more preferably 0.99 or more.

[0024] (Cruise processing) The manufacturing method for cushioning paper preferably includes a crumpling process. That is, it is preferable that the cushioning paper is crumpled. The crumpling process is a process that imparts elongation properties in the longitudinal direction by finely shrinking the paper in the longitudinal direction on a paper machine. As a specific processing method, an example is to install a Kurupack device in part of the paper machine dryer, pass the wet paper between an endless, thick elastic rubber blanket with nip rolls and a heated dryer, and shrink the paper sheets as the blanket, which has been stretched beforehand, contracts. The resulting shrinkage is then dried and fixed so that it does not stretch again in subsequent processes. The speed difference before and after the Kurupack processing is preferably -15% or more, more preferably -13% or more, even more preferably -11% or more, even more preferably -9% or more, and even more preferably -7% or more, and preferably -2% or less, more preferably -3% or less, and even more preferably -4% or less, from the viewpoint of reducing tearing of the protrusions when forming multiple protrusions on the base paper for the cushioning material. Here, the minus sign "-" indicates that the speed is slower after the Kurupack processing.

[0025] <Characteristics of base paper for cushioning material> (Fiber orientation strength) The fiber orientation strength of the base paper for cushioning material is 1.00 or higher, preferably 1.05 or higher, from the viewpoint of ease of manufacturing, and 1.45 or lower, preferably 1.35 or lower, more preferably 1.25 or lower, even more preferably 1.20 or lower, and even more preferably 1.15 or lower, from the viewpoint of reducing tearing of the convex parts when forming the convex parts by imparting multiple convex shapes. The fiber orientation strength of the base paper for cushioning material can be adjusted to the above range by bringing the J / W ratio closer to 1 in the papermaking process or by performing a packing process. The fiber orientation strength of the base paper for cushioning material can be determined by measuring the longitudinal ultrasonic propagation velocity (Vmd) and transverse ultrasonic propagation velocity (Vcd) of the base paper using a fiber / molecular orientation analyzer (for example, "SST-3200" manufactured by Nomura Trading Co., Ltd.), and calculating the ratio (Vmd / Vcd) as the fiber orientation strength. Specifically, it is measured by the method described in the examples. Alternatively, 10 points of measurement can be taken from the sample, and their arithmetic mean can be used as the fiber orientation strength.

[0026] (Clark is scary) The synergistic mean value of the longitudinal and transverse Clark stiffness of the base paper for cushioning material is 33 or higher, preferably 35 or higher, more preferably 41 or higher, from the viewpoint that the shape of the protrusions in the paper cushioning material, which has multiple protrusions formed thereon, can easily recover after being subjected to load, and as a result, the cushioning performance can be easily maintained. Furthermore, from the viewpoint that the protrusions can be easily formed when multiple protrusions are applied, the synergistic mean value of the longitudinal and transverse Clark stiffness of the base paper for cushioning material is 70 or lower, preferably 60 or lower, more preferably 50 or lower. The synergistic mean value of the longitudinal and transverse Clark stiffness of the base paper for cushioning material can be adjusted by the basis weight, thickness, density of the base paper for cushioning material, the type and blend of raw pulp, and the degree of beating. Specifically, increasing the basis weight, thickness, and density of the base paper for cushioning material, increasing the blending ratio of softwood pulp in the raw pulp, or increasing the degree of beating of the raw pulp tends to increase the synergistic mean value of the longitudinal and transverse Clark stiffness of the base paper for cushioning material. The geometric mean of the Clark stiffness in the longitudinal and transverse directions of the base paper for cushioning material is obtained by measuring the Clark stiffness in the longitudinal (MD) and transverse (CD) directions in accordance with JIS P 8143:2009 and calculating their geometric mean. Specifically, it is measured by the method described in the examples.

[0027] The Clark stiffness in the longitudinal direction of the base paper for the cushioning material is preferably 35 or more, more preferably 38 or more, still more preferably 40 or more, and even more preferably 43 or more, from the viewpoint of easily adjusting the multiplicative average value within the above range, and as a result, easily maintaining the cushioning property and easily forming a convex shape. And it is preferably 80 or less, more preferably 75 or less, still more preferably 65 or less, and even more preferably 55 or less. The Clark stiffness in the lateral direction of the base paper for the cushioning material is preferably 30 or more, more preferably 33 or more, still more preferably 35 or more, and even more preferably 38 or more, from the viewpoint of easily adjusting the multiplicative average value within the above range, and as a result, easily maintaining the cushioning property and easily forming a convex shape. And it is preferably 68 or less, more preferably 65 or less, still more preferably 60 or less, and even more preferably 55 or less, and even more preferably 45 or less.

[0028] (Thickness) The thickness of the base paper for the cushioning material is preferably 110 μm or more, more preferably 115 μm or more, and still more preferably 120 μm or more, from the viewpoint of easily adjusting to a desired Clark stiffness and, as a result, reducing breakage of the convex portions when forming a plurality of convex portions on the base paper for the cushioning material and obtaining a paper cushioning material with more excellent cushioning property. And from the viewpoint of reducing breakage of the convex portions when forming a plurality of convex shapes by a paper cushioning material manufacturing machine, it is preferably 160 μm or less, more preferably 150 μm or less, and still more preferably 145 μm or less. When the thickness of the base paper for the cushioning material is below the above upper limit, the clearance between the metal roll and the base paper for the cushioning material does not become too small when applying a plurality of convex shapes by a paper cushioning material manufacturing machine, and breakage is reduced. The thickness of the base paper for the cushioning material is measured in accordance with JIS P 8118:2014, specifically, by the method described in the examples.

[0029] (Grammage) The grammage of the base paper for the cushioning material is preferably 70 g / m 2More preferably 75g / m 2 The above is true, and from the viewpoint of making it easier to create convex shapes when applying multiple convex shapes, 110 g / m² is preferred. 2 More preferably 100g / m 2 More preferably 95 g / m² 2 The following applies: The basis weight of the base paper for cushioning material is measured in accordance with JIS P 8124:2011, specifically by the method described in the examples.

[0030] (density) The density of the base paper for cushioning material is preferably 0.50 g / cm³, from the viewpoint of increasing interfiber bonding and, as a result, reducing tearing of the protrusions when forming multiple protrusions on the base paper for cushioning material. 3 More preferably 0.55 g / cm³ 3 More preferably 0.60 g / cm³ 3 Furthermore, from the viewpoint of making it easier to create multiple convex shapes, a preferably 0.85 g / cm³ is preferred. 3 More preferably, 0.80 g / cm³ 3 More preferably, 0.75 g / cm³ 3 The following applies: The density of the base paper for cushioning material can be adjusted by adjusting the press pressure during the papermaking process. The density of the base paper for cushioning material is calculated from the basis weight and thickness of the base paper.

[0031] (Tensile modulus of elasticity) The synergistic mean of the longitudinal and transverse tensile moduli of the base paper for cushioning material is preferably 1.2 GPa or higher, more preferably 1.4 GPa or higher, even more preferably 1.6 GPa or higher, and even more preferably 1.8 GPa or higher, from the viewpoint of producing a paper cushioning material with superior cushioning properties, and preferably 3.5 GPa or lower, more preferably 3.4 GPa or lower, from the viewpoint of making it easier to create multiple convex shapes. The tensile moduli of the base paper for cushioning material can be adjusted by adjusting the type and blending of the raw pulp, the degree of beating, the density of the base paper for cushioning material, etc. Specifically, increasing the density of the base paper for cushioning material or increasing the proportion of softwood pulp in the raw pulp tends to increase the tensile moduli of the base paper for cushioning material. The transverse tensile modulus of the base paper for cushioning material is preferably 1.6 GPa or higher, more preferably 1.7 GPa or higher, and even more preferably 1.8 GPa or higher, from the viewpoint of reducing tearing of the protrusions when forming multiple protrusions on the base paper for cushioning material, and from the viewpoint of making it easier to create multiple protrusions, it is preferably 4.5 GPa or lower, more preferably 4.0 GPa or lower, even more preferably 3.5 GPa or lower, and even more preferably 3.2 GPa or lower. The longitudinal tensile modulus of the base paper for cushioning material is preferably 1.8 GPa or higher, more preferably 2.0 GPa or higher, and even more preferably 2.1 GPa or higher, from the viewpoint of producing a paper cushioning material with superior cushioning properties, and from the viewpoint of making it easier to create multiple convex shapes, it is preferably 4.5 GPa or lower, more preferably 4.0 GPa or lower, and even more preferably 3.8 GPa or lower. The tensile modulus of the base paper for cushioning material is measured in accordance with JIS P 8113:2006, specifically by the method described in the examples.

[0032] The base paper for cushioning material has been described above. Next, paper cushioning material will be described using Figures 1 to 6. Here, Figure 1 is a schematic diagram illustrating an example of the configuration of paper cushioning material in which a plurality of protrusions are formed on one side of the paper surface of the base paper for cushioning material of the present invention, and Figure 2 is a schematic diagram illustrating an example of the configuration of paper cushioning material in which a plurality of protrusions are formed on both sides of the paper surface of the base paper for cushioning material of the present invention. Figure 3 is a cross-sectional view of the paper cushioning material illustrated in Figure 1, and Figure 4 is a cross-sectional view of the paper cushioning material illustrated in Figure 2. Figure 5 is a plan view showing the paper cushioning material according to the embodiment, and Figure 6 is a cross-sectional view of the paper cushioning material shown in Figure 5.

[0033] [Paper cushioning material] The paper cushioning material of this embodiment has multiple protrusions, 70 per 100 cm, on one or both sides of the paper surface of the cushioning material base paper described above. 2 The above is how it is formed (see Figures 1, 2, and 5). The shape of the protrusion is not particularly limited and can be, for example, hemispherical, semi-ellipsoidal, cylindrical, polygonal, rectangular, etc. Among these, the shape of the protrusion is preferably hemispherical or semi-ellipsoidal. A projection is formed on one side of the paper surface by pressing a protrusion or the like against the cushioning paper base described above, and this projection is called a convex portion. The shape of the cushioning paper base into which the convex portion is formed is not particularly limited, and it may be in the form of a roll, folded, or sheet. Furthermore, from the viewpoint of making the paper cushioning material easy to cut by hand, if the shape of the cushioning paper base is in the form of a roll or folded, it may have perforated sections with multiple perforations in the horizontal direction. It is preferable that the vertical distance between adjacent perforated sections is the same, and from the viewpoint of practicality such as storage and transportation, if the shape of the cushioning paper base is in the form of a folded, it is preferable to fold it alternately at multiple perforated sections and stack it in an accordion-like manner to form a laminate.

[0034] The paper cushioning materials 100, 110, and 120 of this embodiment may have a plurality of protrusions 10 on one side of the paper surface, as shown in Figure 1, or, as shown in Figures 2 and 5, may have a plurality of protrusions 10 on one side of the paper surface and a plurality of protrusions 10' on the side opposite to the side of the paper surface with the plurality of protrusions 10. From the viewpoint of providing a paper cushioning material with superior cushioning properties, it is preferable to have a plurality of protrusions 10 and 10' on both sides of the paper surface, as shown in Figures 2 and 5. Note that if the base paper for the cushioning material has a plurality of protrusions 10 and 10' on both sides of the paper surface, the above-mentioned 100cm 2 The number of protrusions per unit area refers to the sum of the multiple protrusions 10,10' formed on both sides. The arrangement and combination of the multiple protrusions 10, 10' formed on both sides of the paper are not particularly limited. For example, as shown in Figures 1 and 2, the protrusions 10, 10' may be arranged in parallel, or they may be arranged in a staggered pattern, as shown in Figure 5.

[0035] The formation of multiple protrusions may be performed manually or electrically using a paper cushioning material making machine, and is not particularly limited. Examples of paper cushioning material making machines include the "Paper Bubble Machine / PB640EW" and "Paper Bubble Machine / PB340pro" manufactured by WiAir, and the "Paper Bubble Wrap Machine / PB600A" manufactured by Zhangzhou Air Power Packaging Equipment.

[0036] (Number of multiple protrusions) The number of protrusions in the paper cushioning material according to this embodiment is set at 70 per 100cm², from the viewpoint of making it easier for the multiple protrusions to cushion the load when a load is applied to the paper cushioning material, and as a result providing a paper cushioning material with excellent cushioning properties. 2 The above is preferable, with a ratio of 90 pieces / 100cm. 2 The above is 120 pieces / 100cm 2 Therefore, from the viewpoint of making the size of the protrusions sufficiently large and, as a result, providing a paper cushioning material with superior cushioning properties, it is preferable to have 450 pieces / 100cm. 2More preferably 200 pieces / 100cm 2 The following applies:

[0037] (Volume of the convex part) From the viewpoint of improving cushioning performance, the volume of each of the multiple protrusions in the paper cushioning material of this embodiment is preferably 20 mm². 3 More preferably 25mm 3 The above is true, and from the viewpoint of reducing the tearing of the protrusions when forming multiple protrusions, 150 mm is preferable. 3 More preferably 125 mm 3 More preferably, 100 mm 3 More preferably 70 mm 3 The following applies:

[0038] The volume of each of the multiple protrusions 10, 10' represents the average volume of the space occupied by the inside of each protrusion 10, 10' relative to the reference planes R', R, which are the flat surfaces opposite to the paper surface with the protrusions 10, 10' (the surfaces without the protrusions 10, 10') (see Figures 3, 4, and 6). As shown in Figures 1 and 3, for paper cushioning material having multiple protrusions 10 on one side of the paper surface, the volume of each protrusion 10 is the average volume of each of 10 randomly selected protrusions 10, specifically the portion surrounded by the inside of the protrusion 10 and the reference plane R' (the portion that has been given a convex shape by being pressed against by a protrusion, etc.). As shown in Figures 2, 4, and 5, for a paper cushioning material having multiple protrusions 10, 10' on both sides of the paper surface, the volume of each protrusion 10, 10' is the average of the volumes of five randomly selected protrusions 10 from one side of the paper surface, specifically the portion enclosed by the inside of the protrusion 10 and the reference surface R' (the portion that has been pressed against by a protrusion or the like to give it a convex shape), and the volumes of five randomly selected protrusions 10' from the other side of the paper surface, specifically the portion enclosed by the inside of the protrusion 10' and the reference surface R (the portion that has been pressed against by a protrusion or the like to give it a convex shape). The volume of each protrusion is specifically calculated by the method described in the embodiment.

[0039] (Height of the protrusion) From the viewpoint of improving cushioning performance, the height of the protrusions is preferably 1.00 mm or more, more preferably 1.20 mm or more, even more preferably 1.40 mm or more, and even more preferably 1.60 mm or more. Furthermore, from the viewpoint of reducing tearing of the protrusions when forming multiple protrusions, the height is preferably 5.00 mm or less, more preferably 4.00 mm or less, even more preferably 3.00 mm or less, and even more preferably 2.00 mm or less.

[0040] As shown in Figures 3, 4, and 6, the height of the protrusions 10, 10' refers to the average of the maximum heights of the inside of the multiple protrusions 10, 10' (the parts that have been pressed against by protrusions or the like to give them a convex shape), with the flat surface R', R on the opposite side of the paper cushioning material from the protrusions 10, 10' being used as the reference surface R', R. In other words, the height of the protrusions 10 on one side of the paper cushioning material refers to the average of the maximum heights of the inside of the multiple protrusions 10 (the parts that have been pressed against by protrusions or the like to give them a convex shape), from the reference surface R', R, which is the area where there are no protrusions 10' on the paper surface opposite to the paper surface with the multiple protrusions 10'. Similarly, the height of the protrusions 10' on the other side of the paper cushioning material refers to the average of the maximum heights of the inside of the multiple protrusions 10', from the reference surface R, which is the area where there are no protrusions 10 on the paper surface opposite to the paper surface with the multiple protrusions 10' (one side of the paper cushioning material). As shown in Figures 1 and 3, for paper cushioning material having multiple protrusions 10 on one side of the paper surface, the height of the protrusions 10 is the average value of the maximum heights H1 of 10 randomly selected protrusions 10 from the reference plane R'. As shown in Figures 2, 4 and 5, for paper cushioning material having multiple protrusions 10, 10' on both sides of the paper surface, the height of each protrusion 10, 10' is the average value of the maximum heights H2, H3 of the total of 10 protrusions 10, 10'. Specifically, for 5 randomly selected protrusions 10 from one side of the paper surface, the height H2 is the average value of the maximum heights H2 of the inside of the protrusion 10 (the part that has been pressed against by a protrusion or the like to give it a convex shape) from the reference plane R', and for 5 randomly selected protrusions 10' from the other side of the paper surface, the height H3 is the average value of the maximum heights H3 of the inside of the protrusion 10' (the part that has been pressed against by a protrusion or the like to give it a convex shape) from the reference plane R. The height of each of the protrusions 10,10' is specifically measured by the method described in the examples.

[0041] (Distance between convex parts) The distance between adjacent protrusions (W1 in Figure 3, W2 in Figure 4) can be adjusted as appropriate depending on the volume and number of protrusions, preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less, from the viewpoint of improving cushioning performance. There is no particular lower limit, but from the viewpoint of ease of manufacturing, it is preferably 0.5 mm or more. It is preferable that the multiple protrusions are provided at equal intervals. "Equal intervals" means that the difference between the maximum and minimum distances between adjacent protrusions is 10% or less of the maximum distance. For example, in the paper cushioning material shown in Figure 2, if the maximum distance between adjacent protrusions is 2 mm and the minimum distance is 1.8 mm, then this paper cushioning material has multiple protrusions at equal intervals.

[0042] The paper cushioning material of this embodiment can be used as a substitute for bubble wrap. The paper cushioning material of this embodiment is preferably used to fill the gap between a case such as a cardboard box for packaging and the contents such as goods, or to wrap around the contents such as goods, or to attach to the inside of an envelope, etc., so that it can absorb vibrations, shocks, etc. that occur to the contents during transportation. [Examples]

[0043] The features of the present invention will be further described below with reference to examples and comparative examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following specific examples.

[0044] [Evaluation and Analysis] The following evaluations and analyses were performed on the raw pulp, base paper for cushioning material, and paper cushioning material of the examples and comparative examples.

[0045] <Raw pulp> (Canadian standard filtration rate) The Canadian standard hydrophilicity of the raw pulp was measured according to JIS P 8121-2:2012 "Pulp - Hydrophilicity test methods - Part 2: Canadian standard hydrophilicity method".

[0046] <Base paper for cushioning material> (Basic weight) The basis weight of the cushioning paper was determined by conditioned the cushioning paper obtained in the examples and comparative examples for 24 hours under the humidity-controlled environment specified in JIS P 8111:1998, and then measured in accordance with JIS P 8124:2011.

[0047] (thickness) The thickness of the cushioning paper was measured in accordance with JIS P 8118:2014 after the cushioning paper obtained in the examples and comparative examples was conditioned for 24 hours under the humidity-controlled environment specified in JIS P 8111:1998.

[0048] (density) The density of the base paper for the cushioning material was calculated from the basis weight and thickness measured as described above.

[0049] (Fiber orientation strength) The fiber orientation strength of the cushioning material base paper was determined by conditioned the cushioning material base paper obtained in the examples and comparative examples for 24 hours under the humidity-controlled environment specified in JIS P 8111:1998. Then, using a fiber and molecular orientation analyzer manufactured by Nomura Shoji Co., Ltd., product name "SST-3200", the longitudinal ultrasonic propagation velocity (Vmd) and the transverse ultrasonic propagation velocity (Vcd) of the cushioning material base paper were measured, and the ratio (Vmd / Vcd) was determined as the fiber orientation strength. Ten samples were measured, and the arithmetic mean of these measurements was adopted as the fiber orientation strength.

[0050] (Clark is scary) The Clark stiffness in the longitudinal and transverse directions of the base paper for cushioning material was measured in accordance with JIS P 8143:2009 after the base paper obtained in the examples and comparative examples was conditioned for 24 hours under the humidity-controlled environment specified in JIS P 8111:1998. The geometric mean of these measurements was calculated to obtain the geometric mean values ​​of the Clark stiffness in the longitudinal and transverse directions of the base paper for cushioning material.

[0051] (Tensile modulus of elasticity) The longitudinal and transverse tensile moduli of the cushioning material base paper were measured in accordance with JIS P 8113:2006 after the cushioning material base paper obtained in the examples and comparative examples was conditioned for 24 hours under the humidity-controlled environment specified in JIS P 8111:1998. The geometric mean of these values ​​was calculated to obtain the geometric mean of the longitudinal and transverse tensile moduli of the cushioning material base paper.

[0052] <Paper cushioning material> (Height of the protrusion) The flat surface of the paper cushioning material opposite to the surface with the protrusions (the surface without protrusions) was used as the reference plane, and the average of the maximum heights of the inside of each protrusion (the part that has been pressed against by a protrusion or the like to create a convex shape) from this reference plane was defined as the height of the protrusions. The height of the protrusions of the paper cushioning material was defined as the average of the maximum heights of the inside of a total of 10 protrusions (the part that has been pressed against by a protrusion or the like to create a convex shape) from 5 protrusions randomly selected from one side of the paper surface and 5 protrusions randomly selected from the other side of the paper surface, measured using a one-shot 3D shape measuring machine manufactured by Keyence Corporation, product name "Controller VR-3000". Specifically, the inside of the protrusions of the paper cushioning material (the part that has been pressed against by a protrusion or the like to create a convex shape) was observed by 3D measurement, and the measurement value was obtained by setting the region using a three-point circle with volume area measurement using an analysis application.

[0053] (Volume of the convex part) The volume of the protrusions in the paper cushioning material was calculated using the following formula, based on the height and radius of the protrusions, which were obtained by measuring the height of the protrusions as described above. Volume of the convex part = 4 × π × radius of the convex part × radius of the convex part × height of the convex part ÷ 3 ÷ 2

[0054] (Ease of forming a convex shape) From the height of the protrusions obtained by measuring the height of the protrusions as described above, the value of the protrusion height divided by the height of the press mold was calculated and evaluated according to the following criteria. A: 0.9 or higher B: 0.85 or higher and less than 0.9 C: Less than 0.85

[0055] (buffering properties) Paper cushioning material, which had been humidified for 24 hours in a humidity-controlled environment as specified in JIS P 8111:1998, was cut into 100mm x 100mm squares to serve as test specimens. The test specimens were set on the support plate of an A&D Company, Limited product, "Tensilon Universal Testing Machine RTG-1310," which was fitted with a flat compression jig (support plate with a diameter of 150mm, pressure plate with a diameter of 100mm) manufactured by A&D Company, Limited. The pressure plate was lowered at a speed of 50mm / min, and the compressive load when the specimen was compressed to 50% of its thickness was divided by the load area (area of ​​the pressure plate) to determine the compressive stress, which was then evaluated according to the following criteria. A: Compressive stress is 9.0 N / m 2 That's all. B: Compressive stress is 4.5 N / m 2 More than 9.0N / m 2 less than C: Compressive stress is 4.5 N / m 2 less than

[0056] (Tear rate) The number of torn protrusions on the paper cushioning material (250mm x 250mm) after the protrusion formation process was measured, and the tear rate was calculated using the following formula. Tear rate (%) = Number of raised areas with tears ÷ Number of raised areas × 100 The tear was then evaluated according to the following criteria. A: Almost no tears, less than 5% B: There are some tears, but they are within an acceptable range, between 5% and less than 30%. C: Many tears, over 30%

[0057] Example 1 Using 100% by mass of unbleached softwood kraft pulp (NUKP, "N" in Table 1) as the raw material pulp, a pulp slurry was obtained by beating it using a double discreet refiner to achieve a Canadian standard filtration degree of 560 mL. To 100 parts by mass of the obtained pulp slurry (on a solids basis), 0.75 parts by mass of cationized starch (manufactured by Pillar Starch Co., Ltd., trade name "P-3Y") (on a solids basis), 0.1 parts by mass of polyacrylamide-based internal paper strength enhancer (manufactured by Arakawa Chemical Industries, Ltd., trade name "PS379") (on a solids basis), 0.12 parts by mass of rosin sizing agent (manufactured by Arakawa Chemical Industries, Ltd., trade name "Sizing Pine N-811") (on a solids basis), and 1.0 part by mass of aluminum sulfate (on a solids basis) were added to prepare the paper stock. Using this pulp, the target basis weight is 73g / m². 2 As a result, paper was produced using a wet paper machine (product name "Bellform III" manufactured by Mitsubishi Heavy Industries, Ltd.) equipped with an expansion / contraction device (manufactured by Kurupack), at a papermaking speed of 600 m / min, a J / W ratio of 1.000, a reel moisture content of 6.5%, and a speed difference of -5.0% before and after Kurupack processing. Paper was also produced with a nip pressure of 15 kN / m between the nip roll and blanket during Kurupack processing, and a crepe was applied to the surface of the base paper. From this base paper, a roll with a width of 500 mm and a length of 30 m was prepared to obtain base paper for cushioning material. The obtained base paper for cushioning material was placed in an automatic paper cushioning material manufacturing machine (product name "Paper Bubble Machine / PB640EW" manufactured by WiAir) with the short side parallel to the processing area (i.e., with the long side facing the flow direction), and then fed out at a processing speed of 20 m / min to obtain paper cushioning material having multiple protrusions on both sides of the paper surface, as shown in Figure 5. The automatic paper cushioning material manufacturing machine used has a mechanism that forms the paper by passing it between two metal roll nips, and the desired shape of the protrusions (a perfect circle with a diameter of φ6 mm, a protrusion height of 1.75 mm, and a distance of 1.5 mm between protrusions) is formed on the surface of the metal rolls.

[0058] Example 2 The set basis weight is 78g / m². 2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 1.

[0059] Example 3 The set basis weight is 83g / m². 2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 1.

[0060] Example 4 Except for using unbleached hardwood kraft pulp (LUKP, indicated as "L" in Table 1) in addition to unbleached softwood kraft pulp (NUKP) as raw material pulp, and adopting the formulation shown in Table 1, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 3.

[0061] Examples 5 and 6 Except for the raw pulp composition being as shown in Table 1, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0062] Example 7 Except for using deinked pulp (DIP) in addition to unbleached softwood kraft pulp (NUKP) and unbleached hardwood kraft pulp (LUKP) as raw materials, the formulation was as shown in Table 1, and a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0063] Example 8 Except for using the pulp composition shown in Table 1 and setting the J / W ratio during papermaking to 0.996, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0064] Example 9 Except for using the pulp composition shown in Table 1 and setting the J / W ratio during papermaking to 0.997, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0065] Example 10

[0066] Except for using the pulp composition shown in Table 1 and setting the J / W ratio during papermaking to 0.998, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0067] Example 11 The raw pulp composition is as shown in Table 1, and the set basis weight is 88 g / m².2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0068] Example 12 The raw pulp composition is as shown in Table 1, and the set basis weight is 96 g / m². 2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0069] Example 13 The raw pulp composition is as shown in Table 1, and the set basis weight is 109 g / m². 2 Except for setting the density to the values ​​shown in Table 1, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0070] Example 14 The base paper for cushioning material obtained in Example 4 was placed in an automatic paper cushioning material manufacturing machine (product name "Paper Bubble Machine / PB640EW" manufactured by WiAir) so that the short side was parallel to the processing area (i.e., the long side was in the flow direction), and then fed out at a processing speed of 20 m / min to obtain paper cushioning material having multiple protrusions on one side of the paper surface, as shown in Figure 1. The surface of the metal roll of the automatic paper cushioning material manufacturing machine used had the desired protrusion shape (a perfect circle with a diameter of φ8 mm, a protrusion height of 2.5 mm, and a distance between protrusions of 2.0 mm) formed on it.

[0071] Example 15 The base paper for cushioning material obtained in Example 13 was placed in an automatic paper cushioning material manufacturing machine (product name "Paper Bubble Machine / PB640EW" manufactured by WiAir) so that the short side was parallel to the processing area (i.e., the long side was in the direction of flow), and then fed out at a processing speed of 20 m / min to obtain paper cushioning material having multiple protrusions on one side of the paper surface, as shown in Figure 1. The surface of the metal roll of the automatic paper cushioning material manufacturing machine used was formed with the desired shape of protrusions (a perfect circle with a diameter of φ8 mm, a protrusion height of 2.5 mm, and a distance between protrusions of 2.0 mm).

[0072] Comparative Example 1 Except for using the pulp composition shown in Table 1 and setting the J / W ratio during papermaking to 0.994, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0073] Comparative Example 2 Except for using the pulp composition shown in Table 1 and not performing the Kurupack treatment during papermaking, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0074] Comparative Example 3 Except for using the pulp composition shown in Table 1 and a papermaking speed of 450 m / min, the base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0075] Comparative Example 4 The raw pulp composition is as shown in Table 1, and the set basis weight is 115 g / m². 2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0076] Comparative Example 5 The raw pulp composition is as shown in Table 1, and the set basis weight is 60 g / m². 2 Except for the above, a base paper for cushioning material and paper cushioning material were obtained in the same manner as in Example 4.

[0077] The obtained base paper for cushioning material and paper cushioning material were subjected to the measurements and evaluations described above. The results are shown in Tables 1 and 2.

[0078] [Table 1]

[0079] [Table 2]

[0080] From the results of the examples and comparative examples, it can be seen that the base paper for cushioning material of the present invention is easily formed into a convex shape, and that the paper cushioning material obtained by forming multiple convex parts on one or both sides of the surface of the base paper for cushioning material of the present invention has less tearing of the convex parts and excellent cushioning properties. [Industrial applicability]

[0081] The base paper for cushioning materials of the present invention is suitable for use as a base paper for obtaining a paper cushioning material with excellent cushioning properties, as it reduces tearing of the protrusions when multiple protrusion shapes are applied to form the protrusions. [Explanation of Symbols]

[0082] 100,110,120:Paper cushioning material 10,10': convex part H1, H2, H3: Height of the protrusion W1, W2: Distance between adjacent convex parts R,R': Reference surface

Claims

1. 70 or more protrusions per 100 cm on one or both sides of the paper surface ２ The above is formed to create a base paper for cushioning material, The fiber orientation strength is 1.00 or more and 1.45 or less. The geometric mean of the vertical Clark fear score and the horizontal Clark fear score is between 33 and 70. Base paper for cushioning materials.

2. The base paper for cushioning material according to claim 1, wherein the thickness is 110 μm or more and 160 μm or less.

3. The cushioning paper according to claim 1, wherein the content of softwood pulp in the raw pulp constituting the cushioning paper is 80% by mass or more.

4. The base paper for cushioning material according to claim 1, wherein the synergistic mean of the tensile modulus in the longitudinal direction and the tensile modulus in the transverse direction is 1.2 GPa or more and 3.5 GPa or less.

5. Basis weight 70 g / m² ２ 110g / m or more ２ The base paper for cushioning material according to claim 1 is as follows:

6. A plurality of protrusions, 70 per 100 cm, are provided on one or both sides of the surface of the cushioning paper according to any one of claims 1 to 5. ２ A paper cushioning material formed as described above.

7. The volume of each of the aforementioned multiple protrusions is 20 mm ３ 150mm or more ３ The following is the paper cushioning material according to claim 6.

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