Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B29/00—Layered products comprising a layer of paper or cardboard
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
  • B65D65/38—Packaging materials of special type or form
  • B65D65/40—Applications of laminates for particular packaging purposes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
  • Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics

Definitions

• the present invention relates to heat seal paper and packaging paper.
• This application claims priority based on Japanese Patent Application No. 2022-108890 filed with the Japan Patent Office on July 6, 2022, the contents of which are incorporated herein.
• Heat seal paper having a heat seal layer containing a thermoplastic resin is sometimes used as packaging paper in various fields such as foods, medical products, and electronic components (for example, Patent Documents 1 to 5). These heat-sealing layers are provided by coating or thermally laminating a resin layer containing a thermoplastic resin to cover the surface of the paper base material.
• the present invention provides heat seal paper that can be reused as is in a paper machine equipped with an on-machine coater after disintegrating waste paper with water, and can be manufactured with high productivity.
• the present invention has the following aspects.
• [1] has a paper base material; a heat seal component attached to one or both sides of the paper base material; the heat seal component includes a thermoplastic resin; and the JIS of the surface to which the heat seal component is attached.
• a heat seal paper having an Oken air permeability measured in accordance with P 8117:2009 of more than 700 seconds and less than 100,000 seconds.
• the heat-sealing paper according to [1], wherein the surface of the heat-sealing paper to which the heat-sealing component is attached has an Oken type smoothness of 30 seconds or more.
• thermoplastic resin is at least one selected from the group consisting of biodegradable resins and non-petroleum-derived resins.
• the heat sealing component further includes a polyacrylate; the content of the polyacrylate is 0.1 to 3.0 with respect to the total content of thermoplastic resin in the heat sealing component.
• Packaging paper comprising the heat seal paper of any one of [1] to [5].
• heat seal paper is provided that can be reused as is in a paper machine equipped with an on-machine coater after disintegrating the waste paper with water, and can be manufactured with high productivity.
• the heat seal paper of the present invention has a paper base material and a heat seal component attached to one or both sides of the paper base material.
• the heat-sealing paper of the present invention since the Oken air permeability of the surface to which the heat-sealing component is attached is 100,000 seconds or less, the heat-sealing component is applied to the paper base as a discontinuous film with moderate pores on the surface. It is thought that it is attached to the material. Therefore, when disintegrated, the heat seal component becomes extremely fine, and most of it is discharged outside the production system. Therefore, the waste paper can be disintegrated with water and reused as pulp raw material in a paper machine equipped with an on-machine coating machine, resulting in highly productive production.
• the Oken air permeability of the surface to which the heat seal component is attached is more than 700 seconds, more preferably 1000 seconds or more. Since the Oken type air permeability of the surface to which the heat-sealing component is attached is more than 700 seconds, heat-sealability is sufficiently exhibited.
• heat seal paper such as laminated paper, which has an air permeability of more than 100,000 seconds
• heat seal paper which has an air permeability of more than 100,000 seconds
• the resin layer is disintegrated, it remains in the water as film pieces, so if it is reused in a paper machine equipped with an on-machine coating machine, defects and stains may occur, which may adversely affect the operation of the production line.
• the Ohken air permeability is 100,000 seconds or less
• the surface to which the heat sealing component is attached has good air permeability, and the surface is a discontinuous layer with appropriate pores. Conceivable.
• the thickness of the layer is considered to be extremely thin. Therefore, when the heat-sealing paper of the present invention is disintegrated in water, even if the heat-sealing component remains attached, it becomes fine and dispersed in water, so the waste paper can be disintegrated with water and coated on-machine as it is as a pulp raw material. Even if it is reused in a paper machine equipped with machine tools, problems are unlikely to occur. Therefore, the heat seal paper of the present invention can be manufactured with high productivity.
• the paper base material has pulp as its main component.
• the paper base material is not particularly limited as long as it is a commonly used paper.
• a paper base material whose main component is wood pulp can be mentioned.
• a paper base material whose main component is pulp that is easily dispersed in water by mechanical disintegration is preferable.
• “consisting mainly of pulp” means that the content of pulp is 70% by mass or more based on the paper base material.
• the content of pulp relative to the paper base material may be 80% by mass or more, 90% by mass or more, or 100% by mass.
• Examples of the paper base material include bleached kraft paper, unbleached kraft paper, wood-free paper, paperboard, liner paper, coated paper, glossy paper, glassine paper, and graphane paper. Among them, bleached kraft paper, unbleached kraft paper, coated paper, and glossy paper are preferred from the viewpoint of heat sealability of the heat seal paper.
• the paper base pulp is not particularly limited. Any paper pulp can be used. Examples include chemical pulps such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulfite pulp (LBSP), and softwood bleached sulfite pulp (NBSP). In addition, stone ground pulp (GP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemical ground pulp (CGP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), etc. Examples include unbleached pulp, semi-bleached pulp, and bleached pulp. Also included are sulfite pulp, waste paper pulp, and the like.
• LLKP hardwood bleached kraft pulp
• NKP softwood bleached kraft pulp
• LBSP hardwood bleached sulfite pulp
• NBSP softwood bleached sulfite pulp
• GP stone ground pulp
• PGW pressurized stone ground pulp
• RGP refiner ground pulp
• the paper base material may further contain various internal additives.
• internal additives include sizing agents, fillers, paper strength enhancers, retention improvers, pH adjusters, freeness improvers, water resistance agents, softeners, antistatic agents, antifoaming agents, slime control agents, Examples include dyes and pigments.
• the disintegration freeness (freeness) of the paper base material measured according to JIS P8121:2012 is preferably 200 to 600 ml, more preferably 220 to 500 ml, and even more preferably 250 to 450 ml, from the viewpoint of heat sealability.
• the disintegration freeness is Canadian standard freeness, which is measured in accordance with JIS P8121:2012 of the pulp obtained by disintegrating the paper after papermaking in accordance with JIS P8220-1.
• the basis weight of the paper base material is preferably 20 to 500 g/m 2 , more preferably 30 to 350 g/m 2 , even more preferably 35 to 200 g/m 2 .
• the basis weight of the paper base material is measured in accordance with JIS P 8124.
• the thickness of the paper base material is preferably 20 to 650 ⁇ m, more preferably 30 to 450 ⁇ m, and even more preferably 35 to 250 ⁇ m.
• the thickness of the paper base material is equal to or greater than the lower limit of the above numerical range, the strength of the heat seal paper is likely to be improved.
• the thickness of the paper base material is less than or equal to the upper limit within the above numerical range, the disintegration property is likely to be further improved.
• the molding processability of the heat-sealing paper is likely to be improved.
• the thickness of the paper base material is measured in accordance with JIS P 8118.
• the Oken smoothness of the surface to which the heat-sealing component is attached is preferably 30 seconds or more, more preferably 50 seconds or more, and even more preferably 100 seconds or more.
• the upper limit of the Oken type smoothness of the paper base material on the surface to which the heat-sealing component is attached is not particularly limited. Considering that the Oken air permeability of heat seal paper is 100,000 seconds or less, about 2000 seconds is considered to be the upper limit.
• the Oken type smoothness is measured in accordance with JIS P 8155:2010.
• the paper base material may further have an optional layer such as a clay coat layer on at least a portion of one or both sides, if necessary.
• the clay coat layer is for sealing and smoothing the paper base material. Examples of clay include kaolin, talc, and mica.
• the heat seal component includes a thermoplastic resin. Therefore, heat-sealable paper exhibits heat-sealability within a practical heating temperature range.
• thermoplastic resins include polyethylene, polypropylene, olefin-unsaturated carboxylic acid copolymers, biodegradable resins, acrylic resins, ethylene vinyl alcohol, polystyrene resins, polycarbonate resins, polyacetal resins, polyester resins, polyamides, and styrene-butadiene. Examples include latex, polyvinyl alcohol, and polyvinylidene chloride.
• the thermoplastic resin may be a non-petroleum derived resin. One type of thermoplastic resin may be used alone, or two or more types may be used in combination.
• Examples of the olefin-unsaturated carboxylic acid copolymer include ethylene-acrylic copolymer.
• Examples of the acrylic monomer serving as the structural unit of the olefin-acrylic copolymer include: Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, butenetricarboxylic acid; Unsaturated polycarboxylic acid alkyl esters having at least one carboxyl group, such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester; Examples include unsaturated sulfonic acid monomers and their salts, such as acrylamide propane sulfonic acid, sulfoethyl sodium acrylate, and sulfopropyl sodium methacrylate.
• One type of acrylic monomer may be used alone, or two
• the olefin-unsaturated carboxylic acid copolymer can be obtained, for example, by emulsion polymerization of an olefin such as ethylene and an acrylic monomer.
• a commercially available product may be used as the olefin-unsaturated carboxylic acid copolymer.
• Commercially available olefin-unsaturated carboxylic acid copolymers include, for example, Zaixen AC (aqueous dispersion of ethylene/acrylic acid copolymer ammonium salt, copolymerization ratio of acrylic acid 20 mol%) manufactured by Sumitomo Seika Chemical Co., Ltd. ).
• biodegradable resins examples include polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), and poly(3-hydroxybutyrate-co- hydroxyhexanoate) (PHBH).
• PBS polybutylene succinate
• PBSA polybutylene succinate adipate
• PBAT polybutylene adipate terephthalate
• PHBH poly(3-hydroxybutyrate-co- hydroxyhexanoate)
• One type of biodegradable resin may be used alone, or two or more types may be used in combination.
• the biodegradable resin is preferably polylactic acid or polybutylene succinate, and more preferably polylactic acid.
• Polylactic acid may be a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, and a monomer copolymerizable with L-lactic acid and D-lactic acid. It may also be a copolymer with Examples of monomers copolymerizable with L-lactic acid and D-lactic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, and 6-hydroxycaproic acid. However, the invention is not limited to these examples in any way.
• Monomers copolymerizable with L-lactic acid and D-lactic acid may be used alone or in combination of two or more.
• a commercially available product may be used as the polylactic acid.
• Commercial products of polylactic acid include, for example, Landy PL-1000 and Landy PL-3000 (aqueous dispersion of polylactic acid) manufactured by Miyoshi Oil Co., Ltd., and Rezem Y225 (aqueous dispersion of polylactic acid) manufactured by Chukyo Yushi Co., Ltd. Can be mentioned.
• the non-petroleum-derived resin is not particularly limited, and includes various thermoplastic resins. Examples include biomass-derived polyolefin, biomass-derived polyester, biomass-derived polyamide, biomass-derived polyurethane, and biomass-derived cellulose acetate.
• the biomass is preferably derived from plants. Examples include biomass derived from corn and biomass derived from sugarcane.
• One type of non-petroleum-derived resin may be used alone, or two or more types may be used in combination.
• biomass-derived polyolefins examples include polymers of various olefins such as ethylene and propylene, and copolymers of the olefins, but are not limited to these examples. Among these, biomass-derived polypropylene and biomass-derived polyethylene are preferred, and biomass-derived polyethylene is more preferred.
• biomass-derived polyolefin Commercially available products may be used as the biomass-derived polyolefin.
• Commercially available polyolefins derived from biomass include, for example, SBC818 (biomass low density polyethylene) and SGF4950 (biomass high density polyethylene) manufactured by Braskem.
• either or both of the alcohol unit and the carboxylic acid unit are derived from biomass.
• alcohols include diols. Examples include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, decanediol, and 2-ethyl-butyl-1-propanediol.
• alcohol is not limited to these examples.
• one type of alcohol may be used alone, or two or more types may be used in combination.
• carboxylic acid examples include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof.
• carboxylic acid is not limited to these examples.
• one type of carboxylic acid may be used alone, or two or more types may be used in combination.
• aromatic dicarboxylic acids examples include terephthalic acid, isophthalic acid, and phthalic acid.
• derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids (eg, methyl ester, ethyl ester, propyl ester, butyl ester, etc.).
• the aromatic dicarboxylic acid is not limited to these examples.
• the aliphatic dicarboxylic acids include chain or alicyclic dicarboxylic acids having 2 to 40 carbon atoms.
• Examples include oxalic acid, succinic acid, glutaric acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, azelaic acid, dodecadicarboxylic acid, and cyclohexanedicarboxylic acid. is not limited in any way.
• Examples of derivatives of aliphatic dicarboxylic acids include lower alkyl esters of aliphatic dicarboxylic acids (eg, methyl ester, ethyl ester, propyl ester, butyl ester, etc.). Also included are acid anhydrides of aliphatic dicarboxylic acids such as succinic anhydride.
• a commercially available polyester derived from biomass includes, for example, CB602AB (biopolyethylene terephthalate) manufactured by FENC.
• thermoplastic resin is preferably at least one selected from the group consisting of biodegradable resins and non-petroleum derived resins. Since biodegradable resins and non-petroleum-derived resins are often expensive, there is also the advantage that the present invention has great technical significance, that is, it has great significance in improving productivity due to improved disintegration properties.
• the melting point is preferably 130 to 180°C, more preferably 140 to 170°C, and even more preferably 150 to 160°C.
• the melting point of the thermoplastic resin is within the above numerical range, the adhesive strength of the heat seal paper after heat sealing can be further increased.
• the melting point is higher than the general drying temperature in the manufacturing process, it is difficult for the resin of the heat seal component to form a continuous film. Therefore, the heat-seal paper is easily disintegrated in water, and even if it is reused in the paper-making process of the paper base material of a paper machine equipped with an on-machine coater, the defects caused by the heat-seal component are unlikely to occur.
• the melting point of a thermoplastic resin is measured with a differential scanning calorimeter (DSC).
• DSC differential scanning calorimeter
• the total content of thermoplastic resin in the heat seal component is preferably 90% by mass or more, more preferably 90 to 99% by mass, and even more preferably 95 to 99% by mass.
• the total content of the thermoplastic resin in the heat-sealing component is at least the lower limit within the above numerical range, the heat-sealability is likely to be improved.
• the total content of thermoplastic resin in the heat-sealing component is less than or equal to the upper limit within the above numerical range, blocking and excessive foaming can be easily suppressed.
• the heat-sealing component further contains polyacrylate, since it can increase the adhesive strength of the heat-sealing paper after heat-sealing.
• polyacrylates include sodium salts, potassium salts, and ammonium salts of acrylic acids such as polyacrylic acid, acrylic acid-maleic acid copolymers, and acrylic acid-sulfonic acid copolymers; is not limited in any way.
• the content of the polyacrylate is preferably 0.1 to 3.0% by mass, and 0.2% by mass based on the total content of thermoplastic resin in the heat-sealing component. ⁇ 2.0% by mass is more preferred, and 0.5 ⁇ 1.5% by mass is even more preferred.
• the heat sealing component may further contain an auxiliary agent other than the thermoplastic resin as an optional component, if necessary.
• auxiliary agents include antifoaming agents, thickeners, polysaccharide thickeners, neutralizing agents, plasticizers, preservatives, pH adjusters, crosslinking agents, antiblocking agents, lubricants, and dyes.
• the auxiliary agent is not limited to these examples.
• the Oken air permeability of the surface to which the heat sealing component is attached is 100,000 seconds or less.
• the Oken air permeability is preferably 60,000 seconds or less, more preferably 50,000 seconds or less, and even more preferably 10,000 seconds or less.
• the fact that the Ohken air permeability of the heat seal paper is below the above upper limit means that there is a moderate amount of discontinuous portions of the thermoplastic resin, which is the heat seal component, attached to the surface of the paper base material. This suggests that it is in a state of In such a state, even if the heat-seal paper is disintegrated in water and reused in the paper-making process of the paper base material, defects caused by the heat-seal component are unlikely to occur.
• the lower the Oken air permeability of heat-sealing paper the better; however, considering its use as heat-sealing paper, the lower limit is more than 700 seconds, and more preferably 1,000 seconds. That's all.
• the Oken style air permeability is measured in accordance with JIS P 8117:2009.
• the residue rate of the heat seal paper is preferably 1% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.
• the residue rate of heat seal paper is measured as follows. Heat seal paper is immersed in water so that the solid content concentration is 2.0% by mass. Thereafter, the slurry obtained by disintegration for 30 minutes using a pulp disintegration tester conforming to JIS P 8220 is processed through a flat screen with an opening of 0.25 mm, and the dry mass of the residue (reject) is measured.
• the residue ratio is the value obtained by dividing the dry mass of the residue by the dry mass of the heat seal paper and multiplying it by 100.
• the Oken smoothness of the surface to which the heat seal component is attached is preferably 30 seconds or more, more preferably 100 seconds or more, and even more preferably 200 seconds or more.
• the surface smoothness is high and the heat sealability is likely to be improved.
• the upper limit of the Oken type smoothness of the surface to which the heat sealing component is attached is not particularly limited. Considering that the Oken type air permeability is 100,000 seconds or less, about 1,000 seconds is considered to be the upper limit value.
• the amount of thermoplastic resin adhered per unit area to the paper base material is preferably 1 to 10 g/ m2 , more preferably 2 to 8 g/ m2 , and still more preferably 3 to 6 g/ m2 . preferable.
• the amount of the thermoplastic resin adhered per unit area is equal to or greater than the lower limit within the above numerical range, heat sealability is likely to be improved.
• the amount of the thermoplastic resin adhered per unit area is less than or equal to the upper limit within the above numerical range, blocking and generation of stains during the process can be easily suppressed.
• the thickness of the heat seal component attached to the surface of the fibers of the paper base material is considered to be about 10 ⁇ m or less, but is not particularly limited.
• the thickness of the heat seal component on the fiber surface of the paper base material can be confirmed by microscopic observation of the fiber cross section. In a cross-sectional view perpendicular to the plane of the heat-seal paper, a heat-seal layer made of a heat-seal component may be observed, but it is thought that such a heat-seal layer may not always be clearly observed.
• the heat seal component may be attached to one side or both sides of the paper base material. In order to further reduce production costs, it is preferable that the heat-seal component is attached to one side of the paper base material.
• Heat-sealing paper can be manufactured by attaching a heat-sealing component to one or both sides of a paper base material so that the Oken air permeability is 100,000 seconds or less.
• Examples of methods for setting the Ohken air permeability to 100,000 seconds or less include the following methods. ⁇ Use a thermoplastic resin with a melting point of 130 to 180°C. - Make the disintegration freeness of the paper base material 200ml or more.
• the paper base material can be manufactured by, for example, making paper using various paper machines to form a wet paper and drying it.
• the paper machine is not particularly limited. Examples include a fourdrinier paper machine, a gap former paper machine, a cylinder paper machine, and a short wire paper machine. Further, a paper machine equipped with an on-machine coater is preferable since the effects of the present invention can be easily obtained.
• the pulp beating method is not particularly limited.
• the disintegration freeness (freeness), which is an index of the freeness of the pulp, is preferably 200 to 600 ml, more preferably 220 to 500 ml, and even more preferably 250 to 450 ml, from the viewpoint of the air permeability of the heat seal paper and the physical properties of the paper.
• the beaten pulp may be mixed with internal additives such as a sizing agent and a paper strength enhancer, if necessary, and dispersed in water to prepare a pulp slurry having a concentration suitable for paper making.
• the wet paper obtained by the paper machine is preferably dried using a multistage cylinder dryer, an air dryer, or a Yankee dryer.
• the heat-sealable paper of the present invention can be produced, for example, by applying a coating liquid containing a heat-sealing component to one or both sides of a paper base material, and then drying the coating liquid.
• the coating liquid is preferably an aqueous dispersion of a thermoplastic resin or an aqueous emulsion containing a thermoplastic resin.
• an aqueous dispersion or emulsion of a thermoplastic resin is used as a coating liquid, the Oken air permeability of the heat seal paper tends to be 100,000 seconds or less.
• the coating liquid may further contain an auxiliary agent as an optional component in addition to the thermoplastic resin. Details and preferred embodiments of the thermoplastic resin and auxiliary agents are the same as those already described.
• the method of applying the coating liquid is not particularly limited.
• Various commonly available coating devices can be used. Examples of coating machines include blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain coater, slot die coater, gravure coater, champlex coater, brush coater, slide bead coater, and two-roll size press coater. , pound size press coater, rod metering size press coater, blade metering size press coater, short dwell coater, gate roll coater, and nip coater using a calender. Among these, on-machine coating machines are preferred in terms of productivity. Preferred on-machine coating machines include, for example, blade coaters, bar coaters, gate roll coaters, rod metering size press coaters, blade metering size press coaters, and pound size press coaters.
• the heat seal paper may be subjected to a smoothing treatment if necessary.
• the smoothing process can be carried out on-machine or off-machine using a normal smoothing process apparatus such as a super calender, a gloss calender, or a soft calender.
• the paper base material may be smoothed before being coated with the coating liquid.
• the heat seal paper is then wound up into a roll.
• the ends of the rolled paper may be removed using a slitter.
• the paper at both ends, which become waste paper has an Oken air permeability of 100,000 seconds or less, and therefore has good disintegration properties.
• the heat sealing component is attached to the surface of the waste paper as a discontinuous film with appropriate holes. Therefore, after being disintegrated with water, it can be reused as is in a paper machine equipped with an on-machine coating machine.
• the heat-sealing paper described above has an Oken type air permeability of 100,000 seconds or less on the surface to which the heat-sealing component is attached, so it exhibits excellent disintegration properties, and can be heated using an on-machine coating machine. It is possible to reuse the waste paper generated after the sealing component has been applied, as well as the waste paper generated during the operation of the paper machine. As a result, the number of sheets produced per raw material pulp increases, the productivity of heat seal paper is excellent, and paper production costs can be further reduced, achieving further cost reductions.
• heat seal paper is not particularly limited.
• it can be used in various fields as a material for packaging paper.
• it can be applied in various fields such as food, medical products, electronic components, sanitary products, agricultural materials, and building materials.
• ⁇ Raw materials> (Aqueous emulsion containing thermoplastic resin)
• Aqueous emulsion 1 was used to prepare an aqueous dispersion having the composition shown in Table 1.
• the blending ratios of the polyacrylate and antifoaming agent shown in Table 1 are values when the solid content of the thermoplastic resin in the aqueous emulsion 1 is 100% by mass.
• cationized starch GELTRON 18, a product of Oji Cornstarch Co., Ltd.
• GELTRON 18, a product of Oji Cornstarch Co., Ltd. was blended to obtain a pulp slurry.
• a base paper made from pulp slurry at a paper weight of 66 g/m 2 was used as the paper base material.
• An aqueous dispersion was applied on-machine to the felt surface of this paper base material using a rod metering size press coater, and then dried to obtain a heat-sealing paper with a heat-sealing component adhered to one side.
• Examples 2 to 11 Comparative Examples 1 to 3>
• the basis weight of the paper base material, the smoothness of the surface to which the heat-sealing component adheres, and the composition of the aqueous dispersion were changed in each example so that they were as shown in Tables 1 and 2, respectively. Except for this point, the aqueous dispersion was coated on-machine using a rod metering size press coater under the same conditions as in Example 1, and dried to obtain heat-sealing papers having a heat-sealing component adhered to one side.
• the thickness of the heat seal component attached to the heat seal paper in each example was an estimated value calculated by dividing the mass per unit area of the heat seal component attached to the heat seal paper by the density of the heat seal component.
• heat sealability Two sheets of heat-seal paper of each example were stacked so that the sides to which the heat-seal component was attached faced each other, and tested under the conditions of 160°C, 0.2 MPa, and 1 second using a heat-seal tester (Tester Sangyo Co., Ltd. product "TP701B"). The heat sealability was evaluated using the following criteria. A: If the adhesive part is peeled off, the paper base material will be destroyed (material breakage). B: When the adhesive part is peeled off, there is resistance but no destruction occurs (interfacial peeling). C: There is almost no resistance when the adhesive part is peeled off.
• the heat seal paper of each example was used as a sample, and the sample was immersed in water so that the solid content concentration of the sample was 2.0% by mass.
• the dry mass of the residue (reject) when the slurry obtained by disintegrating for 30 minutes using a pulp disintegration tester conforming to JIS P 8220 was processed through a flat screen with an opening of 0.25 mm was measured.
• the value obtained by dividing the dry mass of the residue by the dry mass of the sample and multiplying it by 100 was defined as the residue ratio, and the disintegration property was evaluated according to the following criteria.
• B The residue rate is 1% or more and less than 3%.
• C The residue rate is 3% or more.
• the blending ratios of polyacrylate and antifoaming agent shown in Tables 1 and 2 are values when the solid content of the thermoplastic resin in the aqueous emulsion is 100% by mass.
• heat seal papers with excellent disintegration properties were obtained. Since the Ohken type air permeability is 100,000 seconds or less, film pieces are unlikely to remain after disintegrating the waste paper with water. Therefore, it is thought that it can be reused as is in a paper machine equipped with an on-machine coater. On the other hand, in Comparative Examples 1 and 2, the Oken air permeability was so high that it could not be measured, exceeding 100,000 seconds. Therefore, the disintegration property was insufficient.
• heat seal paper is provided that can be reused as is in a paper machine equipped with an on-machine coater after disintegrating the waste paper with water, and can be manufactured with high productivity.

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• 2023
  • 2023-04-25 WO PCT/JP2023/016327 patent/WO2024009592A1/ja not_active Ceased
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