Foamed paper and paperboard comprising thermo-responsive micro-foaming agent

Abstract

The present invention relates to foamed paper, paperboard, both comprising a thermo-responsive micro-foaming agent, and a method for manufacturing same, and more specifically, to foamed paper, paperboard, and a method for manufacturing same, wherein a micro-foaming agent and a retention enhancer are added to cellulose fibers during the stock preparation step of the papermaking process and then micro-foaming agent is foamed during a high-temperature drying process, whereby the foamed paper and paperboard exhibit excellent impact absorption and cushioning performance. In addition, the present invention relates to an eco-friendly foamed paper and paperboard, and a method for manufacturing same, in which a foamable material capable of expanding in volume is incorporated within a cellulose fiber-based paper network.

Description

Foamed paper and paperboard containing heat-sensitive microfoaming agents

[0001] The present invention relates to foamed paper and paperboard containing a heat-sensitive microfoaming agent, and more particularly, to foamed paper and paperboard exhibiting excellent shock absorption and cushioning performance by adding a microfoaming agent and a retention improver to cellulose fibers in a papermaking process at a paper stock composition stage and then foaming the microfoaming agent during a high-temperature drying process.

[0002]

[0003] The destruction of the ecosystem caused by discarded plastic-based cushioning and packaging materials is accelerating. Styrofoam and other plastic-based cushioning and packaging materials are non-biodegradable when disposed of in soil or the ocean, raising concerns that by 2050, the amount of plastic in the ocean will outnumber the number of fish. Cellulose-based pulp molds are widely used as an alternative to plastic-based cushioning and packaging materials. However, they require excessive volume and a large amount of waste paper fiber and pulp to achieve a cushioning effect, necessitating additional lightweighting methods.

[0004] Due to the limitations described above, cellulose-based pulp molds are widely used as a means of replacing Styrofoam and plastic-based cushioning materials and packaging materials. However, cushioning materials manufactured using the pulp mold method have problems such as increased unit cost of cushioning materials due to the use of excessive amounts of pulp, reduced shock absorption ability, which raises concerns about damage to packaged goods, and increased packaging volume due to excessive volume caused by spaces for providing cushioning performance.

[0005] Due to the above problems, there is a need to develop eco-friendly foam paper and paperboard using foam materials capable of volume expansion within a paper network based on cellulose pulp fibers.

[0006]

[0007] The present invention aims to solve the above problems by providing foamed paper and paperboard including a heat-sensitive microfoaming agent, which is foamed by adding a heat-sensitive microfoaming agent to the inside of a paper network using cellulose pulp fibers as a base material.

[0008] In addition, it is an object of the present invention to provide foamed paper and paperboard manufactured by adding a fine foaming agent to a pulp stock suspension and fixing it within a fiber network.

[0009] In addition, it is an object of the present invention to provide foamed paper and paperboard exhibiting excellent shock absorption and cushioning performance, heat and sound insulation, heat insulation and electricity saving effects.

[0010] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the art from the description of the present invention.

[0011]

[0012] To achieve the above object, the present invention provides foam paper comprising a heat-sensitive microfoaming agent, which comprises cellulose fibers; and additives including a microfoaming agent, a cationic retention enhancer, and a sizing agent.

[0013] In the present invention, the foam paper has a basis weight of 30 to 400 g / m 2 It is characterized by being.

[0014] In the present invention, the cellulose fiber is characterized in that it is a pulp fiber.

[0015] In the present invention, the pulp fiber is characterized in that it is at least one selected from the group consisting of virgin pulp fiber and regenerated pulp fiber.

[0016] In the present invention, the additive is characterized in that 5 to 40 wt% of the fine foaming agent, 0.02 to 0.6 wt% of the retention improving agent, and 0.2 to 0.6 wt% of the sizing agent are added relative to 100 wt% of the dry weight of the cellulose fiber.

[0017] In the present invention, the fine foaming agent is characterized in that it is at least one selected from the group consisting of a water-dispersible acrylic fine foaming agent, a methacrylic fine foaming agent, and an acrylonitrile fine foaming agent.

[0018] In the present invention, the micro foaming agent is characterized in that it is a spherical particle having a diameter of 5 to 20 ㎛.

[0019] In the present invention, the micro foaming agent is characterized in that it foams at 80 to 150°C.

[0020] In the present invention, the cationic retention enhancer is characterized in that it is at least one selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

[0021] In the present invention, the sizing agent is characterized by being at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent.

[0022] In the present invention, the sizing agent is characterized in that it is an alkyl ketene dimer.

[0023] The present invention provides a foamed cardboard comprising a heat-sensitive microfoaming agent, comprising a sheet layer comprising cellulose fibers; and additives including a microfoaming agent, a cationic retention enhancer, and a sizing agent.

[0024]

[0025] By means of solving the above problem, the present invention can provide foamed paper and paperboard including a heat-sensitive microfoaming agent, which is foamed by adding a heat-sensitive microfoaming agent to the inside of a paper network based on cellulose pulp fibers.

[0026] In addition, the present invention can provide foamed paper and a method for producing the same by adding a fine foaming agent to a pulp stock suspension and fixing the fine foaming agent within a fiber network.

[0027] In addition, the present invention can provide foamed paper and paperboard exhibiting excellent shock absorption and cushioning performance, heat and sound insulation, heat insulation and electricity saving effects.

[0028] In addition, the present invention can provide foamed paper and paperboard that do not require the use of a large amount of pulp raw material as in a conventional pulp mold and do not require excessive volume to impart cushioning performance.

[0029] In addition, the present invention can provide environmentally friendly foamed paper and paperboard using a micro foaming agent and cellulose fibers.

[0030] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0031]

[0032] FIG. 1 is a drawing showing a method for manufacturing foam paper including a heat-sensitive microfoaming agent according to the present invention.

[0033] FIG. 2 is a diagram showing a conceptual diagram of when a microfoaming agent is foamed inside a foam paper including a heat-sensitive microfoaming agent according to the present invention.

[0034] FIG. 3 is a drawing showing the surface sizing of foam paper using (a) a size press and the surface of the surface-sized foam paper containing a heat-sensitive microfoaming agent according to the present invention.

[0035] FIG. 4 is a drawing showing a foam paper using foam paper containing a heat-sensitive microfoaming agent according to the present invention.

[0036] FIG. 5 is a drawing showing a paper cup and a paper cup holder using foamed paper containing a heat-sensitive microfoaming agent according to the present invention.

[0037] FIG. 6 is a drawing showing a pulp mold using foamed paper containing a microfoaming agent according to the present invention.

[0038] FIG. 7 is a drawing showing SEM photographs of the shape of the microfoaming agent of the foam paper containing the microfoaming agent according to the present invention (a) before the microfoaming agent is foamed and (b) after the microfoaming agent is foamed.

[0039] FIG. 8 is a drawing showing SEM photographs taken at 100 magnifications of (a) the surface of foam paper not containing a foaming agent, (b) 100 magnifications, (c) 150 magnifications, and (d) 700 magnifications of the surface of foam paper containing a microfoaming agent according to the present invention.

[0040] FIG. 9 is a drawing showing SEM photographs taken at 100 magnifications of a cross-section of foam paper (a) not containing a foaming agent, (b) 100 magnifications, (c) 150 magnifications, and (d) 1,000 magnifications of a cross-section of foam paper containing a microfoaming agent according to the present invention.

[0041] Figure 10 is an example and comparative example according to the present invention (a) basis weight 45 g / m 2 and (b) a basis weight of 100 g / m 2 This is a diagram showing the change in foaming rate according to the amount of foaming agent added to paper.

[0042] Figure 11 shows examples and comparative examples according to the present invention (a) with a basis weight of 45 g / m 2 and (b) a basis weight of 100 g / m 2 This is a drawing showing the change in surface smoothness according to the amount of foaming agent added to paper.

[0043] Figure 12 shows examples and comparative examples according to the present invention (a) with a basis weight of 45 g / m 2 and (b) a basis weight of 100 g / m 2 This is a diagram showing the change in permeability according to the amount of foaming agent added to the paper.

[0044] Figure 13 shows examples and comparative examples according to the present invention (a) with a basis weight of 45 g / m 2 and (b) a basis weight of 100 g / m 2 This is a diagram showing the change in contact angle according to the amount of foaming agent added to paper.

[0045] Figure 14 shows the basis weight of 45 g / m of examples and comparative examples according to the present invention. 2 and basis weight 100 g / m 2 This is a drawing showing the size chart according to the presence or absence of foaming agent added to the paper.

[0046] Figure 15 shows examples and comparative examples according to the present invention (a) with a basis weight of 45 g / m 2 and (b) a basis weight of 100 g / m 2 This is a diagram showing the change in opacity according to the amount of foaming agent added to paper.

[0047] Fig. 16 is a drawing showing a method for manufacturing a foam board including a heat-sensitive micro-foaming agent according to the present invention.

[0048] Figure 17 is a conceptual diagram showing when a microfoaming agent is foamed inside a foam board including a heat-sensitive microfoaming agent according to the present invention.

[0049] Figure 18 is a drawing showing (a) corrugated cardboard including conventional corrugated board as a cushioning material and (b) corrugated cardboard using foamed cardboard including a heat-sensitive micro-foaming agent as a cushioning material according to the present invention.

[0050] FIG. 19 is a drawing showing a multilayer cardboard structure including (a) a filler layer according to the present invention and (b) a multilayer cardboard including foamed cardboard including a heat-sensitive microfoaming agent as a filler layer.

[0051] FIG. 20 is a drawing showing SEM photographs of the shape of the microfoaming agent of the foam board containing the microfoaming agent according to the present invention (a) before the microfoaming agent is foamed and (b) after the microfoaming agent is foamed.

[0052] FIG. 21 is a drawing showing SEM photographs taken at 500 magnification of (a) the surface of a foam cardboard without a foaming agent, (b) 700 magnification of the surface of a foam cardboard containing a microfoaming agent, and (c) 1,000 magnification of the surface of a foam cardboard according to the present invention.

[0053] FIG. 22 is a drawing showing SEM photographs taken at 500 magnification of (a) a cross-section of foam cardboard not containing a foaming agent according to the present invention, (b) at 500 magnification, and (c) at 1,000 magnification of a cross-section of foam cardboard containing a microfoaming agent.

[0054] Figure 23 is a drawing showing the change in foaming rate according to the amount of foaming agent added in examples and comparative examples according to the present invention.

[0055] Figure 24 is a drawing showing surface roughness according to the amount of foaming agent added in examples and comparative examples according to the present invention.

[0056] Figure 25 is a drawing showing the permeability according to the amount of foaming agent added in examples and comparative examples according to the present invention.

[0057] Figure 26 is a drawing showing the size chart according to the amount of foaming agent added in examples and comparative examples according to the present invention.

[0058]

[0059] The terms used in this specification have been selected from widely used, current terms, taking into account the functions of the present invention. However, these terms may vary depending on the intentions of those skilled in the art, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, terms may be arbitrarily selected by the applicant, in which case their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should not be defined simply as names, but rather based on their inherent meanings and the overall content of the present invention.

[0060] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0061] Numerical ranges are inclusive of the values ​​defined in the ranges above. Any maximum numerical limitation given throughout this specification includes any lower numerical limitation, as if that lower numerical limitation were explicitly stated. Any minimum numerical limitation given throughout this specification includes any higher numerical limitation, as if that higher numerical limitation were explicitly stated. Any numerical limitation given throughout this specification will include any better numerical range within the broader numerical range, as if that narrower numerical limitation were explicitly stated.

[0062]

[0063] Foam paper containing heat-sensitive microfoaming agent

[0064] The present invention relates to foamed paper comprising a heat-sensitive microfoaming agent.

[0065] The present invention relates to foamed paper comprising a heat-sensitive microfoaming agent, comprising cellulose fibers; and additives including a microfoaming agent, a cationic retention enhancer, and a sizing agent.

[0066] The above foam paper may provide excellent cushioning performance to the paper because the hydrocarbon inside the microfoaming agent expands in volume by 40 to 80 times at a temperature above an appropriate temperature and remains in a cavity structure with a shell thickness of about 0.05 to 0.5 ㎛. The above foam paper relates to foam paper having excellent cushioning performance by mixing a microfoaming agent, a retention improver, and cellulose fibers in a paper stock composition process and then foaming in a paper drying stage. The above foam paper has the same basis weight (g / m 2 ) may have a large bulk.

[0067] The above foam paper exhibits excellent shock absorption ability due to the foam structure inside the fiber network as shown in Fig. 2, and has a density of 30 to 100 g / m. 2 The low-bay weight foam paper of the range can replace non-biodegradable packaging vinyl such as bubble wrap and cushioning corrugated board such as flat corrugated board, and can be used as wallpaper base paper for shock absorption and insulation purposes, flooring paper for flooring and steel plate interlayer, and printing paper with a large specific volume. In addition, the electrical insulation effect due to the foam structure is also improved, so that it can be used as an insulator between copper wires inside high-voltage and medium-low voltage wires.

[0068] In the present invention, the foam paper has a basis weight of 30 to 400 g / m 2 may be, preferably 45 to 200 g / m 2 This may include, but is not limited to.

[0069] In the present invention, the cellulose fiber may be a pulp fiber.

[0070] In the present invention, the pulp fiber may be at least one selected from the group consisting of virgin pulp fiber and regenerated pulp fiber. The regenerated pulp fiber may include, but is not limited to, recycled paper resources such as newspapers, magazines, and cardboard.

[0071] In the present invention, the additive may be, but is not limited to, 5 to 40 wt% of the fine foaming agent, 0.02 to 0.6 wt% of the retention enhancer, and 0.2 to 0.6 wt% of the sizing agent, relative to 100 wt% of the dry weight of the cellulose fiber.

[0072] If the above-mentioned fine foaming agent is included in an amount of less than 5 wt%, the foaming effect may not be sufficiently exhibited, and if it is included in an amount exceeding 40 wt%, the durability of the foamed paper produced may be reduced. If the above-mentioned retention enhancer is included in an amount of less than 0.02 wt%, the chemical bonding between the cellulose fibers and the fine foaming agent may be reduced. If the above-mentioned sizing agent is included in an amount of less than 0.2 wt%, the durability and durability of the foamed paper may be reduced, and if it is included in an amount exceeding 0.6 wt%, the sizing effect may be reduced due to the sizing agent not reacting with the cellulose fibers.

[0073] In the present invention, the fine foaming agent may be at least one selected from the group consisting of a water-dispersible acrylic fine foaming agent, a methacrylic fine foaming agent, and an acrylonitrile fine foaming agent, and preferably an acrylonitrile fine foaming agent. The acrylonitrile fine foaming agent may include a hydrocarbon compound (blowing agent) that exhibits a foaming effect in a gaseous state, an acrylonitrile monomer that encapsulates the hydrocarbon compound in a shell form, and a surfactant that disperses the monomer that encapsulates the hydrocarbon during emulsion polymerization.

[0074] In the present invention, the microfoaming agent may be a spherical particle having a diameter of 5 to 20 μm, but is not limited thereto. The microfoaming agent may expand to 80 to 100 μm after foaming to form a large number of cavities, thereby improving the lightweight performance of the foamed paper.

[0075] In the present invention, the microfoaming agent may be foamed at a temperature of 80 to 150°C, but is not limited thereto. When the microfoaming agent is heated to 80 to 150°C, the microfoaming agent may be foamed up to 4 to 6 times its diameter and up to 40 to 60 times its volume.

[0076] In the present invention, the cationic retention enhancer may be at least one selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

[0077] The cationic retention enhancer may enhance the chemical bonding between the cellulose fibers and the microfoaming agent. Using cationic natural and synthetic polymeric retention enhancers, widely used in the paper manufacturing process, can not only fix the microfoaming agent to cellulose fibers with a large number of hydroxyl groups (-OH), but also improve the dry strength of the paper.

[0078] The natural polymer-based retention enhancer, such as the cationic starch, may be included in an amount of 0.1 to 0.6 wt% based on 100 wt% of the dry weight of the cellulose fiber, and the synthetic polymer-based retention enhancer, such as the cationic polyacrylamide, polyvinylamine, and glyoxylated polyacrylamide, may be included in an amount of 0.02 to 0.4 wt% based on 100 wt% of the dry weight of the cellulose fiber, but is not limited thereto.

[0079] In the present invention, the sizing agent may be at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent. The neutral sizing agent may be used when water resistance is required for foam paper. The neutral sizing agent may preferably be an alkyl ketene dimer, and the acidic sizing agent may preferably be rosin-alum.

[0080] In the present invention, the sizing agent may be an alkyl ketene dimer. The alkyl ketene dimer may directly bond with the hydroxyl group (-OH) of cellulose to form a hydrophobic barrier film on the paper.

[0081] As shown in Fig. 3, the foam paper may be coated with oxidized starch, cationic starch, etc. on the surface of the foam paper using a size press to improve surface strength and printability.

[0082] The above foam paper may be used as a covering paper for fruits during fruit cultivation, as shown in Fig. 4. When used as a covering paper as described above, the internal foam structure of the covering paper may diffusely reflect sunlight to help uniformly color the fruits, prevent damage from diseases and pests, provide heat retention when the temperature suddenly drops, and prevent damage to the fruits due to external impact during transportation and storage after harvest.

[0083] The above foam paper may be used as paper cup base paper or cup holder base paper as shown in Fig. 5. When used as paper cup base paper or cup holder base paper as described above, it has excellent heat and cold insulation effects, and the frictional resistance of the base paper is excellent, so that the paper cup holder can be prevented from easily falling out of the cup or the paper cup itself from moving on a surface such as a glass table.

[0084] The above foam paper may be applicable to the manufacture of a pulp mold as shown in Fig. 6. Such a pulp mold may have a significantly improved cushioning effect due to its foam structure while reducing the amount of pulp raw material used in the pulp mold per unit volume.

[0085]

[0086] Method for producing foam paper containing a heat-sensitive microfoaming agent

[0087] The present invention relates to a method for producing foamed paper comprising a heat-sensitive microfoaming agent.

[0088] The present invention relates to a method for producing foamed paper comprising a heat-sensitive microfoaming agent, the method comprising the steps of: dissociating and diluting cellulose fibers; refining the diluted fiber suspension; adding and mixing additives including a microfoaming agent, a cationic retention improver, and a sizing agent to the refining fiber suspension to produce a mixture; supplying the mixture to a paper machine to form and dehydrate a sheet; pressing the sheet; and drying the pressed sheet to foam the microfoaming agent contained in the sheet.

[0089] The above manufacturing method relates to a method for manufacturing foamed paper having excellent cushioning performance by mixing a fine foaming agent with a retention improver and cellulose fibers during the paper composition process and then foaming the paper during the drying stage.

[0090] Foam paper manufactured according to the above manufacturing method may be foam paper including a heat-sensitive microfoaming agent, including cellulose fibers; and additives including a microfoaming agent, a cationic retention improver, and a sizing agent.

[0091] The above foam paper may provide excellent cushioning performance to the paper because the hydrocarbon inside the microfoaming agent expands in volume by 40 to 80 times at a temperature above an appropriate temperature and remains in a cavity structure with a shell thickness of about 0.05 to 0.5 ㎛. The above foam paper relates to foam paper having excellent cushioning performance by mixing a microfoaming agent, a retention improver, and cellulose fibers in a paper stock composition process and then foaming in a paper drying stage. The above foam paper has the same basis weight (g / m 2 ) may have a large bulk.

[0092] In the present invention, the cellulose fiber may be a pulp fiber.

[0093] In the present invention, the pulp fiber may be at least one selected from the group consisting of virgin pulp fiber and regenerated pulp fiber. The regenerated pulp fiber includes, but is not limited to, recycled paper resources such as newspapers, magazines, and cardboard.

[0094] In the present invention, the step of dissociating and diluting the cellulose fibers may be diluted so that the cellulose fibers are 3 to 5 wt% relative to 100 wt% of the suspension, but is not limited thereto.

[0095] In the present invention, the step of beating the diluted fiber suspension may be to be beaten so that the fluidity is 300 to 500 mL CSF, but is not limited thereto. Through the step of beating, the bonding strength between the fibers of the cellulose fibers may be improved.

[0096] In particular, when using recycled pulp fiber as a raw material for the foam paper, the paper strength may decrease due to recycling, so it may be necessary to compensate for the decrease in physical strength, such as the step of refining or treatment with a dry strength enhancer.

[0097] In the present invention, the step of preparing a mixture by adding and mixing the additives may be, but is not limited to, adding 5 to 40 wt% of the fine foaming agent, 0.02 to 0.6 wt% of the retention improving agent, and 0.2 to 0.6 wt% of the sizing agent relative to 100 wt% of the dry weight of the cellulose fiber.

[0098] If the above-mentioned fine foaming agent is added in an amount of less than 5 wt%, the foaming effect may not be sufficiently achieved, and if it is added in an amount exceeding 40 wt%, the durability of the foamed paper may be reduced. If the above-mentioned retention enhancer is added in an amount of less than 0.02 wt%, the chemical bonding between the cellulose fibers and the fine foaming agent may be reduced. If the above-mentioned sizing agent is added in an amount of less than 0.2 wt%, the durability and durability of the foamed paper may be reduced, and if it is added in an amount exceeding 0.6 wt%, the sizing effect may be reduced due to the sizing agent not reacting with the cellulose fibers.

[0099] In the present invention, the fine foaming agent may be at least one selected from the group consisting of a water-dispersible acrylic fine foaming agent, a methacrylic fine foaming agent, and an acrylonitrile fine foaming agent, and preferably an acrylonitrile fine foaming agent. The acrylonitrile fine foaming agent may include a hydrocarbon compound (blowing agent) that exhibits a foaming effect in a gaseous state, an acrylonitrile monomer that encapsulates the hydrocarbon compound in a shell form, and a surfactant that disperses the monomer that encapsulates the hydrocarbon during emulsion polymerization.

[0100] In the present invention, the microfoaming agent may be a spherical particle having a diameter of 5 to 20 μm, but is not limited thereto. The microfoaming agent may expand to 80 to 100 μm after foaming to form a large number of cavities, thereby improving the lightweight performance of the foamed paper.

[0101] In the present invention, the cationic retention enhancer may be at least one selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

[0102] The cationic retention enhancer may enhance the chemical bonding between the cellulose fibers and the microfoaming agent. Using cationic natural and synthetic polymeric retention enhancers, widely used in the paper manufacturing process, can not only fix the microfoaming agent to cellulose fibers with a large number of hydroxyl groups (-OH), but also improve the dry strength of the paper.

[0103] The natural polymer-based retention enhancer, such as the cationic starch, may be included in an amount of 0.1 to 0.6 wt% based on 100 wt% of the dry weight of the cellulose fiber, and the synthetic polymer-based retention enhancer, such as the cationic polyacrylamide, polyvinylamine, and glyoxylated polyacrylamide, may be included in an amount of 0.02 to 0.4 wt% based on 100 wt% of the dry weight of the cellulose fiber, but is not limited thereto.

[0104] In the present invention, the sizing agent may be at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent. The neutral sizing agent may be used when water resistance is required for foam paper. The neutral sizing agent may preferably be an alkyl ketene dimer, and the acidic sizing agent may preferably be rosin-alum.

[0105] In the present invention, the sizing agent may be an alkyl ketene dimer. The alkyl ketene dimer may directly bond with the hydroxyl group (-OH) of cellulose to form a hydrophobic barrier film on the paper.

[0106] In the present invention, the step of drying the pressed sheet to foam the fine foaming agent contained in the sheet may be, but is not limited to, drying at 80 to 150°C. Through the step of drying at 80 to 150°C, the fine foaming agent contained in the sheet may be foamed up to 4 to 6 times the diameter of the fine foaming agent and up to 40 to 60 times the volume.

[0107] In the present invention, the foam paper manufactured according to the manufacturing method of the foam paper has a basis weight of 30 to 400 g / m 2 It may be, preferably 45 to 200 g / m 2 This may include, but is not limited to.

[0108]

[0109] Foamed cardboard containing heat-sensitive microfoaming agent

[0110] The present invention relates to a foamed cardboard comprising a heat-sensitive micro-foaming agent.

[0111] The present invention relates to a foamed cardboard comprising a heat-sensitive microfoaming agent, comprising a sheet layer comprising cellulose fibers; and additives including a microfoaming agent, a cationic retention enhancer, and a sizing agent.

[0112] The above foamed board may provide excellent cushioning performance to paper because the hydrocarbon inside the microfoaming agent expands in volume by 40 to 80 times at a temperature above an appropriate temperature and remains in a cavity structure with a shell thickness of about 0.05 to 0.5 ㎛. The above foamed board relates to foamed board having excellent cushioning performance by mixing a microfoaming agent, a retention improver, and cellulose fibers in a paper stock composition process and then foaming in a paperboard drying stage. The above foamed board has an equal basis weight (g / m 2 ) may have a large bulk.

[0113] In the present invention, the foamed cardboard may be a multi-layer cardboard including 2 to 10 layers of the sheet layers.

[0114] In the present invention, the sheet layer may be formed by foaming the micro-foaming agent. As shown in Fig. 17, the foamed cardboard exhibits excellent shock absorption due to the foamed structure within the fiber network, and thus can replace cushioning cardboard such as flat corrugated cardboard, and can be used as wallpaper base paper, flooring paper, and steel plate interlayer paper for shock absorption and insulation purposes. In addition, the electrical insulation effect due to the foamed structure is also improved, and thus can be used as an insulator between copper wires within high-voltage and medium-low-voltage wires.

[0115] In the present invention, the foamed cardboard has a basis weight of 100 to 400 g / m 2 It may be, preferably 250 to 400 g / m 2 This may include, but is not limited to.

[0116] In the present invention, the cellulose fiber may be a pulp fiber.

[0117] In the present invention, the pulp fiber may be at least one selected from the group consisting of virgin pulp fiber and regenerated pulp fiber. The regenerated pulp fiber may include, but is not limited to, recycled paper resources such as newspapers, magazines, and cardboard.

[0118] In the present invention, the additive may be, but is not limited to, 5 to 40 wt% of the fine foaming agent, 0.02 to 0.6 wt% of the retention enhancer, and 0.2 to 0.6 wt% of the sizing agent, relative to 100 wt% of the dry weight of the cellulose fiber.

[0119] If the above-mentioned fine foaming agent is included in an amount of less than 5 wt%, the foaming effect may not be sufficiently exhibited, and if it is included in an amount exceeding 40 wt%, the durability of the foamed paperboard produced may be reduced. If the above-mentioned retention enhancer is included in an amount of less than 0.02 wt%, the chemical bonding between the cellulose fibers and the fine foaming agent may be reduced. If the above-mentioned sizing agent is included in an amount of less than 0.2 wt%, the durability and longevity of the foamed paper may be reduced, and if it is included in an amount exceeding 0.6 wt%, the sizing effect may be reduced due to the sizing agent not reacting with the cellulose fibers.

[0120] In the present invention, the fine foaming agent may be at least one selected from the group consisting of a water-dispersible acrylic fine foaming agent, a methacrylic fine foaming agent, and an acrylonitrile fine foaming agent, and preferably an acrylonitrile fine foaming agent. The acrylonitrile fine foaming agent may include a hydrocarbon compound (blowing agent) that exhibits a foaming effect in a gaseous state, an acrylonitrile monomer that encapsulates the hydrocarbon compound in a shell form, and a surfactant that disperses the monomer that encapsulates the hydrocarbon during emulsion polymerization.

[0121] In the present invention, the microfoaming agent may be a spherical particle having a diameter of 5 to 20 μm, but is not limited thereto. The microfoaming agent may expand to 80 to 100 μm after foaming to form a large number of cavities, thereby improving the lightweight performance of the foamed cardboard.

[0122] In the present invention, the microfoaming agent may be foamed at a temperature of 80 to 150°C, but is not limited thereto. When the microfoaming agent is heated to 80 to 150°C, the microfoaming agent may be foamed up to 4 to 6 times its diameter and up to 40 to 60 times its volume.

[0123] In the present invention, the cationic retention enhancer may be at least one selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

[0124] The cationic retention enhancer may enhance the chemical bonding between the cellulose fibers and the microfoaming agent. Using cationic natural and synthetic polymeric retention enhancers, widely used in the paperboard manufacturing process, can not only help bind the microfoaming agent to cellulose fibers with a large number of hydroxyl groups (-OH), but also improve the dry strength of the paperboard.

[0125] The natural polymer-based retention enhancer, such as the cationic starch, may be included in an amount of 0.1 to 0.6 wt% based on 100 wt% of the dry weight of the cellulose fiber, and the synthetic polymer-based retention enhancer, such as the cationic polyacrylamide, polyvinylamine, and glyoxylated polyacrylamide, may be included in an amount of 0.02 to 0.4 wt% based on 100 wt% of the dry weight of the cellulose fiber, but is not limited thereto.

[0126] In the present invention, the sizing agent may be at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent. The neutral sizing agent may be used when water resistance is required for foam paper. The neutral sizing agent may preferably be an alkyl ketene dimer, and the acidic sizing agent may preferably be rosin-alum.

[0127] In the present invention, the sizing agent may be an alkyl ketene dimer. The alkyl ketene dimer may directly bond with the hydroxyl group (-OH) of cellulose to form a hydrophobic barrier film on the paper.

[0128] Conventional high-basis-weight paperboards based on cellulose fibers have a reduced thickness due to hydrogen bonding between cellulose fibers during the pressing and drying processes of the papermaking process. To improve this, high-basis-weight paperboards are manufactured by laminating paperboard manufactured with bleached (chemical) thermomechanical pulp in the middle layer (midlle or filler ply) or using a large amount of pulp raw materials. However, as the thickness of the paperboard decreases, the stiffness of the paperboard decreases, which can cause major problems in printing or packaging paper. Therefore, the foamed paperboard according to the present invention can be manufactured by laminating foamed paperboard in the middle layer instead of using thermomechanical pulp.

[0129] The above-mentioned foam board may be used as a corrugated board and back liner as shown in (b) of Fig. 18 when manufacturing corrugated board including a corrugated board as shown in (a) of Fig. 18, and may not only improve the cushioning effect but also simplify the cardboard manufacturing process. In particular, when the above-mentioned foam board is used as a corrugated board having a corrugation height of 1.2 mm or less, such as an E-corrugation of corrugated board, the compressive strength and cushioning effect of the corrugated board may be improved.

[0130] In addition, the foam board is 150 to 400 g / m as shown in Fig. 19. 2 When using high basis weight foam board of the range, it can be used instead of thermomechanical pulp for bulk improvement in the inner ply or filler ply when manufacturing multi-layer board using multiple headboxes, and the bulk of the multi-layer board can be improved by at least 2 times, resulting in excellent cushioning effect, which can enhance the protection effect of packaged goods against external impact. For example, 300 g / m basis weight foam board 2 When manufacturing 3 ply cardboard, the middle ply (filler ply, 100 g / m 2) was manufactured by adding 10% of a microfoaming agent to 100% of the dry weight of the pulp, and the foaming rate or bulk increase rate was more than twice that of a 3-ply board using thermomechanical pulp as the middle ply.

[0131]

[0132] Method for producing foamed cardboard containing a heat-sensitive micro-foaming agent

[0133] The present invention relates to a method for manufacturing foamed cardboard comprising a heat-sensitive micro-foaming agent.

[0134] The present invention relates to a method for producing foamed paperboard containing a heat-sensitive microfoaming agent, comprising the steps of: dissociating and diluting cellulose fibers; refining the diluted fiber suspension; adding and mixing additives including a microfoaming agent, a cationic retention improver, and a sizing agent to the refining fiber suspension to produce a mixture; supplying the mixture to a paper machine to form and dehydrate a sheet; pressing the sheet; and drying the pressed sheet to foam the microfoaming agent contained in the sheet.

[0135] The above manufacturing method relates to a method for manufacturing foamed cardboard having excellent cushioning performance by mixing a fine foaming agent with cellulose fibers and a retention improving agent during the material composition process and then foaming the paperboard during the drying stage.

[0136] The foamed cardboard manufactured according to the above manufacturing method may be a foamed cardboard including a heat-sensitive microfoaming agent, including cellulose fibers; and additives including a microfoaming agent, a cationic retention enhancer, and a sizing agent.

[0137] The above-mentioned foam board may provide excellent cushioning performance to the paperboard because the hydrocarbon inside the microfoaming agent expands by 40 to 80 times in volume at a temperature above an appropriate temperature and remains in a cavity structure with a shell thickness of about 0.05 to 0.5 ㎛. The above-mentioned foam board relates to foam board having excellent cushioning performance by mixing a microfoaming agent, a retention improver, and cellulose fibers in a papermaking process and then foaming in a drying stage of the paperboard. The above-mentioned foam board has the same basis weight (g / m 2 ) may have a large bulk.

[0138] In the present invention, the cellulose fiber may be a pulp fiber.

[0139] In the present invention, the pulp fiber may be at least one selected from the group consisting of virgin pulp fiber and regenerated pulp fiber. The regenerated pulp fiber includes, but is not limited to, recycled paper resources such as newspapers, magazines, and cardboard.

[0140] In the present invention, the step of dissociating and diluting the cellulose fibers may be diluted so that the cellulose fibers are 3 to 5 wt% relative to 100 wt% of the suspension, but is not limited thereto.

[0141] In the present invention, the step of beating the diluted fiber suspension may be to be beaten so that the fluidity is 300 to 500 mL CSF, but is not limited thereto. Through the step of beating, the bonding strength between the fibers of the cellulose fibers may be improved.

[0142] In particular, when using recycled pulp fiber as a raw material for the foamed cardboard, the strength of the cardboard may decrease due to recycling, so it may be necessary to compensate for the decrease in physical strength, such as the step of refining or treatment with a dry strength enhancer.

[0143] In the present invention, the step of preparing a mixture by adding and mixing the additives may be, but is not limited to, adding 5 to 40 wt% of the fine foaming agent, 0.02 to 0.6 wt% of the retention improving agent, and 0.2 to 0.6 wt% of the sizing agent relative to 100 wt% of the dry weight of the cellulose fiber.

[0144] If the above-mentioned fine foaming agent is added in an amount of less than 5 wt%, the foaming effect may not be sufficiently achieved, and if it is added in an amount exceeding 40 wt%, the durability of the foamed cardboard produced may be reduced. If the above-mentioned retention enhancer is added in an amount of less than 0.02 wt%, the chemical bonding between the cellulose fibers and the fine foaming agent may be reduced. If the above-mentioned sizing agent is added in an amount of less than 0.2 wt%, the durability and longevity of the foamed cardboard may be reduced, and if it is added in an amount exceeding 0.6 wt%, the sizing effect may be reduced due to the sizing agent not reacting with the cellulose fibers.

[0145] In the present invention, the fine foaming agent may be at least one selected from the group consisting of a water-dispersible acrylic fine foaming agent, a methacrylic fine foaming agent, and an acrylonitrile fine foaming agent, and preferably an acrylonitrile fine foaming agent. The acrylonitrile fine foaming agent may include a hydrocarbon compound (blowing agent) that exhibits a foaming effect in a gaseous state, an acrylonitrile monomer that encapsulates the hydrocarbon compound in a shell form, and a surfactant that disperses the monomer that encapsulates the hydrocarbon during emulsion polymerization.

[0146] In the present invention, the microfoaming agent may be a spherical particle having a diameter of 5 to 20 μm, but is not limited thereto. The microfoaming agent may expand to 80 to 100 μm after foaming to form a large number of cavities, thereby improving the lightweight performance of the foamed cardboard.

[0147] In the present invention, the cationic retention enhancer may be at least one selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

[0148] The cationic retention enhancer may enhance the chemical bonding between the cellulose fibers and the microfoaming agent. Using cationic natural and synthetic polymeric retention enhancers, widely used in the paperboard manufacturing process, can not only help bind the microfoaming agent to cellulose fibers with a large number of hydroxyl groups (-OH), but also improve the dry strength of the paperboard.

[0149] The natural polymer-based retention enhancer, such as the cationic starch, may be included in an amount of 0.1 to 0.6 wt% based on 100 wt% of the dry weight of the cellulose fiber, and the synthetic polymer-based retention enhancer, such as the cationic polyacrylamide, polyvinylamine, and glyoxylated polyacrylamide, may be included in an amount of 0.02 to 0.4 wt% based on 100 wt% of the dry weight of the cellulose fiber, but is not limited thereto.

[0150] In the present invention, the sizing agent may be at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent. The neutral sizing agent may be used when water resistance is required for foamed cardboard. The neutral sizing agent may preferably be an alkyl ketene dimer, and the acidic sizing agent may preferably be rosin-alum.

[0151] In the present invention, the sizing agent may be an alkyl ketene dimer. The alkyl ketene dimer may directly bond with the hydroxyl group (-OH) of cellulose to create a hydrophobic barrier film on the cardboard.

[0152] In the present invention, the step of pressing the sheet may additionally include a step of pressing and bonding 2 to 10 of the sheets.

[0153] In the present invention, the step of drying the pressed sheet to foam the fine foaming agent contained in the sheet may be, but is not limited to, drying at 80 to 150°C. Through the step of drying at 80 to 150°C, the fine foaming agent contained in the sheet may be foamed up to 4 to 6 times the diameter of the fine foaming agent and up to 40 to 60 times the volume.

[0154] In the present invention, the foamed cardboard manufactured according to the method for manufacturing the foamed cardboard has a basis weight of 30 to 400 g / m 2 It may be, preferably 45 to 200 g / m 2 This may include, but is not limited to.

[0155] Conventional high-basis-weight paperboards based on cellulose fibers have a reduced thickness due to hydrogen bonding between cellulose fibers during the pressing and drying processes of the papermaking process. To improve this, high-basis-weight paperboards are manufactured by laminating paperboard manufactured with bleached (chemical) thermomechanical pulp in the middle layer (midlle or filler ply) or using a large amount of pulp raw materials. However, as the thickness of the paperboard decreases, the stiffness of the paperboard decreases, which can cause major problems in printing or packaging paper. Therefore, the foamed paperboard according to the present invention can be manufactured by laminating foamed paperboard in the middle layer instead of using thermomechanical pulp.

[0156] As shown in (a) of Fig. 18, when manufacturing corrugated board including a corrugated core, if the foamed cardboard is used for the corrugated core and back liner as shown in (b) of Fig. 18, not only can the cushioning effect be improved, but the cardboard manufacturing process can also be simplified. In particular, if the foamed cardboard is used to replace a corrugated core having a corrugation height of 1.2 mm or less, such as the E-corrugation of corrugated board, the compressive strength and cushioning effect of the corrugated board can be improved.

[0157] In addition, the manufacturing method of the foam cardboard is as shown in Fig. 19, and the 150 to 400 g / m 2 When manufacturing high basis weight foam board of a range, when manufacturing multi-layer board using multiple headboxes, it can be used instead of thermomechanical pulp for bulk improvement in the inner ply or filler ply, which can improve the bulk of the multi-layer board by at least 2 times, and the protection effect of the packaged goods against external impact can be improved due to the excellent cushioning effect. For example, 300 g / m basis weight 2 When manufacturing 3 ply cardboard, the middle ply (filler ply, 100 g / m 2) was manufactured by adding 10% of a fine foaming agent to 100% of the dry weight of the pulp, and the foaming rate or bulk increase rate was more than twice that of a 3-ply board using thermomechanical pulp as the middle ply.

[0158]

[0159] Example

[0160] Hereinafter, examples of the present invention will be described in detail, but it is obvious that the present invention is not limited to the following examples.

[0161] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. The present invention is defined solely by the scope of the claims.

[0162]

[0163] <Example 1> Weight 45 g / m 2 Foam paper containing heat-sensitive microfoaming agent

[0164] Bleached hardwood kraft pulp was fed into a pulper for pulp dissociation, and water was added to dissociate the pulp at a concentration of 3 to 5%. The dissociated pulp suspension was transferred to a disc refiner, refined to a freeness of 300 mL, and then transferred to a blend chest. 30 wt% of a fine foaming agent, 0.1 wt% of a cationic retention improver, and 0.5 wt% of an alkyl ketene dimer (AKD) sizing agent were added to the transferred suspension as additives based on 100 wt% of the dry weight of the pulp, and mixed. The pulp suspension mixed with the additives was compressed through a sheet-making process, and then transferred to a drying device at a temperature of 100 to 150°C and dried to foam the fine foaming agent to obtain a basis weight of 45 g / m. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0165]

[0166] <Example 1-1>

[0167] The same method as Example 1 except that 10 wt% of the microfoaming agent was added, and the basis weight was 45 g / m. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0168]

[0169] <Example 1-2>

[0170] The same method as Example 1 except that 20 wt% of the microfoaming agent was added, and the basis weight was 45 g / m. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0171]

[0172] <Example 2> Basis weight 100 g / m 2 Foam paper containing heat-sensitive microfoaming agent

[0173] 100 g / m 2Except that it was controlled to be 100 g / m in weight in the same manner as Example 1 above. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0174]

[0175] <Example 2-1>

[0176] The same method as Example 2 except that 10 wt% of the microfoaming agent was added, and the basis weight was 100 g / m. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0177]

[0178] <Example 2-2>

[0179] The same method as Example 2 except that 20 wt% of the microfoaming agent was added, and the basis weight was 100 g / m. 2 A foam paper containing a heat-sensitive micro-foaming agent was manufactured.

[0180]

[0181] <Comparative Example 1> Basis weight 45 g / m 2 Paper that does not contain microfoaming agents

[0182] Bleached hardwood kraft pulp was placed in a pulper for pulp dissociation, and water was added to dissociate the pulp at a concentration of 3 to 5%. The dissociated pulp suspension was transferred to a disc refiner, refined to a freeness of 300 mL, and then transferred to a raw material blend chest. The pulp suspension was pressed through a sheet-making process, and then transferred to a drying device at a temperature of 100 to 150°C and dried to a basis weight of 45 g / m. 2 Paper was manufactured that did not contain any semantic foaming agent.

[0183]

[0184] <Comparative Example 2> Basis weight 100 g / m 2 Paper that does not contain microfoaming agents

[0185] 100 g / m 2 Except that it was controlled to be 100 g / m in weight in the same manner as Example 2 above. 2 Paper was manufactured without containing microfoaming agent.

[0186]

[0187] <Experimental Example 1> Surface Analysis of Foam Paper

[0188] To analyze the surface of the foam paper of the present invention, the following experiment was performed.

[0189]

[0190] <Experimental Example 1-1> SEM analysis before and after microfoam foaming

[0191] The microfoam contained in the foam paper manufactured in Example 1 was analyzed by taking pictures before and after foaming using a scanning electron microscope (SEM) at 200x magnification, and the results are shown in Fig. 7.

[0192] As shown in Fig. 7, the microfoaming agent included in the foamed paper of Example 1 showed a significant increase in diameter and volume after foaming compared to before foaming.

[0193]

[0194] <Experimental Example 1-2> SEM analysis of paper surface with and without microfoaming agent

[0195] The surface of the foam paper manufactured in Example 1 was photographed using a scanning electron microscope (SEM) at magnifications of 100x, 150x, and 700x, and the surface of the paper manufactured in Comparative Example 1 was photographed using an SEM at magnifications of 100x, and the results are shown in Fig. 8.

[0196] As shown in Fig. 8 (a), the surface of the paper not containing the microfoaming agent of Comparative Example 1 exhibited a very dense texture due to bonding between cellulose fibers. On the other hand, as shown in Figs. 8 (b), (c), and (d), the surface of the foamed paper containing the microfoaming agent of Example 1 exhibited that the foamed microfoaming agent particles were contained between the cellulose fibers.

[0197]

[0198] <Experimental Example 1-3> SEM analysis of cross-sections of paper with and without microfoaming agent

[0199] The cross-section of the foam paper manufactured in Example 1 was photographed using a scanning electron microscope (SEM) at magnifications of 100x, 150x, and 1,000x, and the cross-section of the paper manufactured in Comparative Example 1 was photographed using an SEM at magnifications of 100x, and the results are shown in Fig. 9.

[0200] As shown in Fig. 9 (a), the cross-section of the paper not containing the microfoaming agent of Comparative Example 1 showed a very dense structure due to bonding between cellulose fibers. On the other hand, as shown in Figs. 9 (b), (c), and (d), the cross-section of the foamed paper containing the microfoaming agent of Example 1 showed the formation of honeycomb-shaped hollow cavities created by the foamed microfoaming agents.

[0201]

[0202] Through the above results, it was confirmed that the foam paper including the heat-sensitive microfoaming agent according to the present invention has microfoaming agents foamed between cellulose fibers, and thus can exhibit shock absorption, heat and sound blocking, heat insulation, and electrical insulation effects.

[0203]

[0204] <Experimental Example 2> Analysis of physical properties of foam paper

[0205] To evaluate the physical properties of the foam paper of the present invention, the following experiments were conducted.

[0206]

[0207] <Experimental Example 2-1> Measurement of thickness and foaming rate of foam paper

[0208] The thickness of the paper manufactured in the above Examples 1, 1-1, 1-2, 2, 2-1, 2-2, and Comparative Examples 1 and 2 was measured in accordance with ISO 534, and the results are shown in Fig. 10. The foaming rate of the foamed paper was calculated by substituting the thickness of the paper before and after foaming of the microfoaming agent included in the paper into the following [Mathematical Formula 1].

[0209] [Mathematical Formula 1]

[0210] Expansion ratio (%) = {[thickness of foam paper (㎛) - thickness of paper before foaming (㎛) / thickness of paper before foaming (㎛)] × 100

[0211] As shown in Fig. 10 (a), the basis weight is 45 g / m 2 As a result of measuring the thickness and foaming ratio of the paper, the paper not including the microfoaming agent of Comparative Example 1 had a thickness of 94 ㎛, whereas the foamed paper of Examples 1, 1-1, and 1-2 had a thickness after foaming that increased from 230 ㎛ to 570 ㎛ and a foaming ratio of 190% to 240% as the amount of the microfoaming agent added when manufacturing the foamed paper increased.

[0212] Also, as shown in Fig. 10 (b), the basis weight is 100 g / m 2As a result of measuring the thickness and foaming ratio of the paper, the paper not including the microfoaming agent of Comparative Example 2 had a thickness of 154 ㎛, whereas the foamed paper of Examples 2, 2-1, and 2-2 had a thickness after foaming that increased from 526 ㎛ to 1,015 ㎛ and a foaming ratio of 242% to 559% as the amount of the microfoaming agent added when manufacturing the foamed paper increased.

[0213] Through the above results, it was confirmed that the foam paper including the heat-sensitive micro-foaming agent according to the present invention exhibits an excellent foaming rate.

[0214]

[0215] <Experimental Example 2-2> Measurement of surface smoothness of foam paper

[0216] The surface smoothness of the paper manufactured in the above Examples 1, 1-1, 1-2, 2, 2-1, 2-2, and Comparative Examples 1 and 2 was measured according to ISO 5627, and the results are shown in Fig. 11.

[0217] As shown in Fig. 11, compared to the paper not including the microfoaming agent of Comparative Examples 1 and 2, the foamed paper of Examples 1, 1-1, 1-2, 2, 2-1 and 2-2 showed that as the amount of the microfoaming agent added during the manufacture of the foamed paper increased, the foaming rate increased, and the surface unevenness due to the spherical particles of the foaming agent increased, and thus the surface smoothness decreased.

[0218] Through the above results, it was confirmed that the foam paper containing the heat-sensitive microfoaming agent according to the present invention exhibits low surface smoothness, and thus is suitable for application as a packaging material, cushioning material, etc.

[0219]

[0220] <Experimental Example 2-3> Measurement of the permeability of foam paper

[0221] The permeability of the paper manufactured in Examples 1, 1-1, 1-2, 2, 2-1, 2-2, and Comparative Examples 1 and 2 was measured according to ISO 5636-5, and the results are shown in Fig. 12.

[0222] As shown in Fig. 12, compared to the paper not including the microfoaming agent of Comparative Examples 1 and 2, the foamed paper of Examples 1, 1-1, 1-2, 2, 2-1 and 2-2 showed that as the amount of the microfoaming agent added during manufacture of the foamed paper increased, the foaming rate increased, and many gaps were formed between the foamed spherical particles inside the foamed paper, allowing compressed air to easily escape, resulting in a rapid decrease in air permeability.

[0223] Through the above results, it was confirmed that the foam paper containing the heat-sensitive microfoaming agent according to the present invention exhibits low air permeability, and thus is suitable for application as a packaging material, cushioning material, etc.

[0224]

[0225] <Experimental Example 3> Evaluation of water resistance of foam paper

[0226] To evaluate the water resistance of the foam paper of the present invention, the following experiment was conducted.

[0227]

[0228] <Experimental Example 3-1> Contact angle measurement of foam paper

[0229] The contact angles of the papers manufactured in Examples 1, 1-1, 1-2, 2, 2-1, 2-2, and Comparative Examples 1 and 2 were measured according to ISO / TS 14778, and the results are shown in Fig. 13.

[0230] As shown in Fig. 13, compared to the paper not containing the microfoaming agent of Comparative Examples 1 and 2, the foamed paper of Examples 1, 1-1, 1-2, 2, 2-1 and 2-2 showed an increase in the contact angle as the amount of the microfoaming agent added during the manufacture of the foamed paper increased.

[0231] Through the above results, it was confirmed that the foam paper including the heat-sensitive microfoaming agent according to the present invention exhibits excellent water resistance.

[0232]

[0233] <Experimental Example 3-2> Measuring the size of foam paper

[0234] The sketch size of the paper manufactured in the above Examples 1 and 2 and Comparative Examples 1 and 2 was measured by measuring the time it takes for a 1% concentration of ferric chloride solution dropped on the paper surface to develop color when it meets a 2% ammonium thiocyanate solution on the bottom surface of the paper, according to KS M 7025, and the results are shown in Fig. 14.

[0235] As shown in Fig. 14, the papers not including the microfoaming agent of Comparative Examples 1 and 2 took 50 and 190 seconds, respectively, while the foamed papers of Examples 1 and 2 showed that the microfoaming agent of the foamed paper blocked the large pores through which liquid could penetrate into the interior of the foamed paper as it foamed, and thus the two reagents did not meet even after 10 minutes, resulting in no color development.

[0236] Through the above results, it was confirmed that the foam paper including the heat-sensitive microfoaming agent according to the present invention exhibits excellent water resistance.

[0237]

[0238] <Experimental Example 4> Evaluation of the opacity of foam paper

[0239] In order to evaluate the opacity of the foam paper of the present invention, the opacity of the paper manufactured in Examples 1, 1-1, 1-2, 2, 2-1, 2-2, and Comparative Examples 1 and 2 was measured according to ISO 2471, and the results are shown in Fig. 15.

[0240] As shown in Fig. 15, compared to the paper not including the microfoaming agent of Comparative Examples 1 and 2, the foamed paper of Examples 1, 1-1, 1-2, 2, 2-1 and 2-2 showed an improved light scattering ability and increased opacity because the foaming agent inside the foamed paper scattered light incident on the paper surface and prevented it from penetrating.

[0241] Through the above results, it was confirmed that the foam paper including the heat-sensitive microfoaming agent according to the present invention exhibits excellent opacity.

[0242]

[0243] <Example 3> Foamed cardboard containing 10 wt% of a heat-sensitive micro-foaming agent

[0244] Bleached hardwood kraft pulp was fed into a pulper for pulp dissociation, and water was added to dissociate the pulp at a concentration of 3 to 5%. The dissociated pulp suspension was transferred to a disc refiner, refined to a freeness of 300 mL, and then transferred to a blend chest. 10 wt% of a fine foaming agent, 0.1 wt% of a cationic retention improver, and 0.5 wt% of an alkyl ketene dimer (AKD) sizing agent were added to the transferred suspension as additives based on 100 wt% of the dry weight of the pulp, and mixed. The pulp suspension mixed with the additives was processed into a sheet-making process to obtain a basis weight of 100 g / m. 2A foam board was manufactured. Afterwards, the foam board was subjected to a multiply-forming process, and these three layers were laminated and pressed, and then transferred to a drying device at a temperature of 100 to 150°C and dried to foam the fine foaming agent, thereby manufacturing a foam board containing a heat-sensitive fine foaming agent.

[0245]

[0246] <Example 4> Foamed cardboard containing 15 wt% of a heat-sensitive micro-foaming agent

[0247] A foamed cardboard was manufactured in the same manner as in Example 3, except that 15 wt% of the heat-sensitive microfoaming agent was included.

[0248]

[0249] <Comparative Example 3> Cardboard not containing microfoaming agent

[0250] Bleached hardwood kraft pulp was placed in a pulper for pulp dissociation, and water was added to dissociate the pulp at a concentration of 3 to 5%. The dissociated pulp suspension was transferred to a disc refiner, refined to a freeness of 300 mL, and then transferred to a raw material blend chest. The pulp suspension was processed into a sheet-making process to obtain a basis weight of 100 g / m. 2 A foamed cardboard was manufactured. Afterwards, the foamed cardboard was subjected to a multiply-forming process, and these three layers were laminated and pressed. After being pressed, it was transferred to a drying device at a temperature of 100 to 150°C and dried to manufacture a cardboard that does not contain a fine foaming agent.

[0251]

[0252] <Experimental Example 5> Surface Analysis of Foamed Cardboard

[0253] To analyze the surface of the foam board of the present invention, the following experiment was conducted.

[0254]

[0255] <Experimental Example 5-1> SEM analysis before and after microfoam foaming

[0256] The microfoam contained in the foam board manufactured in Example 3 was analyzed by taking pictures before and after foaming using a scanning electron microscope (SEM) at 200x magnification, and the results are shown in Fig. 20.

[0257] As shown in Fig. 20, the microfoaming agent included in the foamed cardboard of Example 3 showed a significant increase in diameter and volume after foaming compared to before foaming.

[0258]

[0259] <Experimental Example 5-2> SEM analysis of cardboard surface with and without microfoaming agent

[0260] The surface of the cardboard manufactured in Comparative Example 3 was photographed using a scanning electron microscope (SEM) at 500x magnification, and the surface of the foam cardboard manufactured in Example 1 was photographed using an SEM at 700x and 1,000x magnification, and the results are shown in Fig. 21.

[0261] As shown in Fig. 21 (a), the surface of the cardboard not containing the microfoaming agent of Comparative Example 1 exhibited a very dense texture due to bonding between cellulose fibers. On the other hand, as shown in Figs. 21 (b) and (c), the surface of the foamed cardboard containing the microfoaming agent of Example 3 exhibited that the foamed microfoaming agent particles were contained between the cellulose fibers.

[0262]

[0263] <Experimental Example 5-3> SEM analysis of cross-sections of cardboard with and without microfoaming agent

[0264] The surface of the cardboard manufactured in Comparative Example 3 was photographed using a scanning electron microscope (SEM) at 1,000x magnification, and the surface of the foam cardboard manufactured in Example 1 was photographed using an SEM at 500x and 1,000x magnification, and the results are shown in Fig. 22.

[0265] As shown in Fig. 22 (a), the cross-section of the cardboard not containing the microfoaming agent of Comparative Example 3 showed a very dense structure due to bonding between cellulose fibers. On the other hand, as shown in Figs. 22 (b) and (c), the cross-section of the foamed cardboard containing the microfoaming agent of Example 3 showed the formation of honeycomb-shaped hollow cavities created by the foamed microfoaming agents.

[0266]

[0267] Through the above results, it was confirmed that the foamed cardboard including the heat-sensitive microfoaming agent according to the present invention has the microfoaming agents foamed between cellulose fibers, and thus can exhibit shock absorption, heat and sound blocking, heat insulation, and electrical insulation effects.

[0268]

[0269] <Experimental Example 6> Analysis of Physical Properties of Foamed Cardboard

[0270] To evaluate the physical properties of the foamed cardboard of the present invention, the following experiments were conducted.

[0271]

[0272] <Experimental Example 6-1> Measurement of thickness and foaming rate of foam cardboard

[0273] The thickness of the cardboard manufactured in Examples 3 and 4 and Comparative Example 3 was measured according to ISO 534, and the results are shown in Fig. 23. The foaming rate of the foamed cardboard was calculated by substituting the thickness of the cardboard before and after foaming of the microfoaming agent included in the cardboard into the following [Mathematical Formula 1].

[0274] [Mathematical Formula 1]

[0275] Expansion ratio (%) = {[thickness of foam cardboard (㎛) - thickness of cardboard before foaming (㎛) / thickness of cardboard before foaming (㎛)] × 100

[0276] As shown in Fig. 23, the thickness and foaming rate of the cardboard were measured, and the foaming rate of the cardboard not including the micro-foaming agent of Comparative Example 3 was found to have increased by 95 and 102%, respectively, compared to the foaming rate of the cardboard of Examples 3 and 4.

[0277] Through the above results, it was confirmed that the foamed cardboard including the heat-sensitive micro-foaming agent according to the present invention exhibits an excellent foaming rate.

[0278]

[0279] <Experimental Example 6-2> Measurement of surface roughness of foam cardboard

[0280] The surface smoothness of the cardboard manufactured in Examples 3 and 4 and Comparative Example 3 was measured according to ISO 8791-4, and the results are shown in Fig. 24.

[0281] As shown in Fig. 24, compared to the cardboard not including the microfoaming agent of Comparative Example 3, the foamed cardboard of Examples 3 and 4 did not have a microfoaming agent added to the back and surface of the multilayer cardboard, and the microfoaming agent was added only to the filler layer corresponding to the middle layer of the multilayer cardboard, so it was found that it did not have a significant effect on the surface roughness of the multilayer cardboard.

[0282] Through the above results, it was confirmed that the foamed cardboard including the heat-sensitive micro-foaming agent according to the present invention is suitable for application as a packaging material, cushioning material, etc., because the surface roughness does not increase.

[0283]

[0284] <Experimental Example 6-3> Measurement of the permeability of foam cardboard

[0285] The permeability of the cardboard manufactured in Examples 3 and 4 and Comparative Example 3 was measured according to ISO 5636-5, and the results are shown in Fig. 25.

[0286] As shown in Fig. 25, compared to the cardboard not including the microfoaming agent of Comparative Example 3, the foaming cardboard of Examples 3 and 4 showed that as the amount of the microfoaming agent added during the manufacture of the foaming cardboard increased, the foaming rate increased, and many voids were formed between the foamed spherical particles inside the foaming cardboard, allowing compressed air to easily escape, resulting in a rapid decrease in air permeability.

[0287] Through the above results, it was confirmed that the foamed cardboard containing the heat-sensitive micro-foaming agent according to the present invention exhibits low air permeability, and thus is suitable for application as a packaging material, cushioning material, etc.

[0288]

[0289] <Experimental Example 7> Evaluation of water resistance of foam cardboard

[0290] In order to evaluate the water resistance of the foam board of the present invention, the size of the foam board was also measured.

[0291] The size of the cardboard manufactured in Examples 3 and 4 and Comparative Example 3 was measured according to ISO 535, and the results are shown in Fig. 26.

[0292] As shown in Fig. 26, the size charts of the foamed cardboard of Examples 3 and 4 were similar to the size chart of the cardboard of Comparative Example 3 that did not contain the microfoaming agent.

[0293] Through the above results, it was confirmed that the foamed cardboard including the heat-sensitive micro-foaming agent according to the present invention exhibits excellent water resistance.

[0294]

[0295] The foam paper according to the present invention can be used as a buffering paper that can replace bubble wrap, depending on the foaming ratio, as a wire insulating paper, as a paper for over-wrapping, as wallpaper, as a base paper for disposable paper cups and cup holders, as a filler layer for multi-layer cardboard, as a buffering paper to replace the corrugated cardboard core, etc.

[0296] Through this, it is expected that packaging materials that depend on plastic or Styrofoam can be replaced with eco-friendly cushioning materials based on cellulose fibers, thereby contributing to alleviating environmental pollution problems caused by non-biodegradable packaging materials.

Claims

1. Cellulose fibers; and Foamed paper comprising a heat-sensitive microfoaming agent, the foamed paper comprising an additive comprising a microfoaming agent, a cationic retention enhancer and a sizing agent.

2. In paragraph 1, The above foam paper, Weight 30 to 400 g / m 2 A foam paper comprising a heat-sensitive microfoaming agent, characterized in that:

3. In paragraph 1, The above cellulose fibers, Foamed paper comprising a heat-sensitive micro-foaming agent, characterized in that it is pulp fiber.

4. In paragraph 3, The above pulp fibers, Foamed paper comprising a heat-sensitive microfoaming agent, characterized in that at least one selected from the group consisting of virgin pulp fibers and regenerated pulp fibers.

5. In paragraph 1, The above additives are, Foamed paper comprising a heat-sensitive microfoaming agent, characterized in that 5 to 40 wt% of the microfoaming agent, 0.02 to 0.6 wt% of the retention improving agent, and 0.2 to 0.6 wt% of the sizing agent are added relative to 100 wt% of the dry weight of the cellulose fiber.

6. In paragraph 1, The above fine foaming agent is, Foam paper comprising a heat-sensitive microfoaming agent, characterized in that at least one selected from the group consisting of a water-dispersible acrylic microfoaming agent, a methacrylic microfoaming agent, and an acrylonitrile microfoaming agent.

7. In paragraph 1, The above fine foaming agent is, Foam paper comprising a heat-sensitive microfoaming agent, characterized in that the particles are spherical particles having a diameter of 5 to 20 ㎛.

8. In paragraph 1, The above fine foaming agent is, Foam paper comprising a heat-sensitive micro-foaming agent, characterized in that it foams at 80 to 150°C.

9. In paragraph 1, The above cationic retention enhancer is, Foamed paper comprising a heat-sensitive microfoaming agent, characterized in that at least one is selected from the group consisting of cationic starch, cationic polyacryl amide, polyvinyl amine, and glyoxylated polyacrylamide.

10. In paragraph 1, The above size is, Foam paper comprising a heat-sensitive microfoaming agent, characterized by at least one selected from the group consisting of a neutral sizing agent and an acidic sizing agent.

11. In paragraph 1, The above size is, Foamed paper comprising a heat-sensitive micro-foaming agent characterized by being an alkyl ketene dimer.

12. Cellulose fibers; and Foamed cardboard comprising a heat-sensitive microfoaming agent, comprising a sheet layer comprising additives including a microfoaming agent, a cationic retention enhancer and a sizing agent.

Images