Paper and pulp molds

Abstract

We provide novel paper and other materials with excellent water resistance. [Solution] A paper comprising pulp and an additive, wherein the additive comprises a cationic polymer compound and an anionic styrene-acrylic copolymer.

Description

[Technical Field]

[0001] This invention relates to paper and pulp molds. [Background technology]

[0002] Traditionally, there has been a movement to replace plastic containers with paper containers such as pulp molded containers as part of the trend toward reducing plastic use. In replacing plastic containers with paper containers, fluororesin is being added to the pulp slurry to provide water resistance to the paper. Furthermore, improving water resistance by applying a resin layer to the surface of the paper through coating with resin components or laminating with a resin film is also being considered. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-046500 [Patent Document 2] Japanese Patent Publication No. 2013-64204 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, recently, the use of perfluorinated compounds has also been restricted. Furthermore, applying a resin layer to paper increases the number of steps involved and presents separation challenges during paper recycling.

[0005] Therefore, the present invention aims to provide a novel paper or the like with excellent water resistance. [Means for solving the problem]

[0006] [1] Paper comprising pulp and an additive, wherein the additive comprises a cationic polymer compound and an anionic styrene-acrylic copolymer. [2] In the wavenumber-transmittance graph based on the FTIR analysis of the surface of the paper, the ratio of the height of the absorption peak near 1730 cm -1 to the height of the absorption peak near 3300 cm -1 is 0.30 or more. The paper according to [1]. [3] The cationic polymer compound is an aqueous polymer compound. The paper according to [1] or [2]. [4] The cationic polymer compound is at least one selected from the group consisting of polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, cationic epoxy resin, cationized starch, polyamino acid, melamine resin, polyacrylamide, polyvinylpyridine, polyvinylimidazole, polyguanidine, polyamino ester, and polydimethyldiallylammonium chloride. The paper according to any one of [1] to [3]. [5] The molecular weight of the cationic polymer compound is 25,000 or more. The paper according to any one of [1] to [4]. [6] The anionic styrene-acrylic copolymer has a nitrile group. The paper according to any one of [1] to [5]. [7] The internal additive further contains an anionic paraffin wax. The paper according to any one of [1] to [6]. [8] In the wavenumber-transmittance graph based on the FTIR analysis of the surface of the paper, the ratio of the height of the absorption peak near 2915 cm -1 to the height of the absorption peak near 3300 cm -1 is 0.55 or more. The paper according to [7]. [9] It is a pulp mold. The paper according to any one of [1] to [8].

Advantages of the Invention

[0007] A novel paper with excellent water resistance is provided.

Embodiments for Carrying Out the Invention

[0008] In this specification, "main component" means a component having a concentration of more than 50% by mass unless otherwise specified.

[0009] (Paper) The paper according to this embodiment includes pulp and internal additives. The internal additives include a cationic polymer compound and an anionic styrene-acrylic copolymer.

[0010] (Pulp) There is no particular limitation on the pulp. Examples of the pulp are wood pulps such as softwood pulp and hardwood pulp, non-wood pulps such as straw pulp, bagasse pulp, reed pulp, kenaf pulp, kozo pulp, and mulberry pulp. The pulp may be a mechanical pulp such as harvested pulp or thermomechanical pulp, or a chemical pulp such as kraft pulp, sulfide pulp, or alkaline pulp. Also, the pulp may be bleached pulp or unbleached pulp.

[0011] It is preferable that the pulp includes hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP).

[0012] There is no particular limitation on the mass ratio of LBKP and NBKP. For example, the mass ratio of LBKP and NBKP may be 70:30 to 80:20. The paper may further contain other pulp components.

[0013] The total proportion of LBKP and NBKP in the total pulp constituting the paper may be 50% or more, 80% or more, 90% or more, or 95% or more in terms of mass ratio.

[0014] When the paper is a pulp mold, the pulp may be an unbleached kraft pulp such as softwood unbleached kraft pulp (NUKP) or hardwood unbleached kraft pulp (LUKP). The total proportion of NUKP and LUKP in the total pulp constituting the pulp mold may be 50% or more, 80% or more, 90% or more, or 95% or more in terms of mass ratio.

[0015] Paper typically contains pulp as its main component. The pulp content in paper is not particularly limited, but may be 60% by mass or more, 65% by mass or more, 70% by mass or more, 99% by mass or less, 98% by mass or less, or 97% by mass or less.

[0016] (Oral additive) The paper further contains an additive. The additive includes at least a cationic polymer compound and an anionic styrene-acrylic copolymer.

[0017] (Cationic polymer compounds) A cationic polymer is a polymer compound having a cationic functional group. Cationic polymers can function as fixing agents. Examples of fixing effects include bonding pulp fibers together and bonding pulp fibers to other internal additives. Examples of cationic functional groups include amino groups, pyridine groups, phosphonium groups, amide groups, guanidine groups, imidazolium groups, carbazole groups, and carbamoyl groups. Cationic polymers may be aqueous polymers. For example, cationic polymers may be water-soluble and can be used in the form of an aqueous solution. In another embodiment, cationic polymers may be used in the form of an aqueous dispersion (e.g., emulsion or suspension) containing the polymer compound.

[0018] Examples of cationic polymer compounds include at least one selected from the group consisting of polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, cationic epoxy resin, cationized starch, polyamino acids, melamine resin, polyacrylamide, polyvinylpyridine, polyvinylimidazole, polyguanidine, polyaminoester, and polydimethyldiallylammonium chloride.

[0019] (cationic epoxy resin) Cationic epoxy resins are polymer compounds having both cationic functional groups and epoxy groups, and may be polycondensates of a compound having cationic functional groups and an epihalohydrin compound. Examples include polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, and polyamine polyamide epichlorohydrin resins.

[0020] (Cationized starch) Cationic starch is modified starch into which a cationic functional group has been introduced. Examples of cationic functional groups include amino groups, quaternary ammonium groups such as trimethylammonium groups, imino groups, pyridinium groups, and imidazolium groups.

[0021] (Polyamino acids) Polyamino acids are polypeptides formed by the linkage of multiple amino acids. Examples include polylysine, polyglutamic acid, polyaspartic acid, and polyornithine.

[0022] (Properties of cationic polymer compounds) The cationic polymer compound may be in the form of a salt, such as a hydrochloride salt. The cationic polymer compound may be linear or branched in structure.

[0023] The molecular weight of the cationic polymer compound can be between 2,000 and 2,000,000, and from the viewpoint of improving the adhesion of other internal additives to paper, it is preferably between 25,000 and 2,000,000, more preferably between 200,000 and 2,000,000, and even more preferably between 300,000 and 2,000,000.

[0024] (Amount of cationic polymer compound) There are no particular limitations on the amount of cationic polymer compound blended, but it may be 0.01% to 10% of the pulp mass, 0.05% to 10%, 0.10% to 10%, 0.20% to 10%, 0.30% to 10%, 0.01% to 8.0%, 0.01% to 5.0%, 0.01% to 2.0%, or 0.01% to 1.0%. From the viewpoint of preventing aggregation of internal additives, it may be 0.01% to 1.0%, 0.05% to 1.0%, 0.10% to 1.0%, 0.20% to 1.0%, or 0.30% to 1.0%.

[0025] (Anionic styrene-acrylic copolymer) Anionic styrene-acrylic copolymers are copolymers of styrenes, (meth)acrylates, and (meth)acrylic acid. Anionic styrene-acrylic copolymers can function as water-resistant and oil-resistant agents.

[0026] In this specification, (meth)acrylate refers to both acrylate and methacrylate, and (meth)acrylic acid refers to both acrylic acid and methacrylic acid.

[0027] The styrenes used as components of styrene-acrylic copolymers are polymerizable compounds having a styrene skeleton, such as styrene, α-methylstyrene (o-methylstyrene, m-methylstyrene, p-methylstyrene, or a mixture thereof), styrene dimers, styrene trimers, and styrene derivatives (p-dimethylsilyl styrene, p-tert-butyldimethylsiloxystyrene, p-tert-butylstyrene).

[0028] Styrene compounds may be one type or two or more types. Among these, styrene is preferred, and when two or more types of styrene compounds are used, it is preferable to use styrene as the main component, for example, by making styrene the largest mass proportion of all styrene compounds.

[0029] There are no particular limitations on the (meth)acrylate used as a component of the styrene-acrylic copolymer, for example, methyl (meth)acrylate, ethyl (meth)acrylate, iso-propyl (meth)acrylate, allyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, iso-amyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-stearyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, (meth)acrylate, (meth)acrylate (Meth)Cyclohexyl Acrylate, (Meth)4-Tert-Butylcyclohexyl Acrylate, (Meth)Isobornyl Acrylate, (Meth)Tricyclodecanyl Acrylate, (Meth)Dicyclopentadienyl Acrylate, (Meth)Adamantyl Acrylate, (Meth)Glycidyl Acrylate, (Meth)Tetrahydrofurfuryl Acrylate, (Meth)2-Methoxyethyl Acrylate, (Meth)2-Ethoxyethyl Acrylate, (Meth)Dimethylaminoethyl Acrylate, (Meth)Diethylaminoethyl Acrylate, Trifluoroethyl Methacrylate, Tetrafluoropropyl Methacrylate, Pentafluoropropyl Methacrylate, Octafluoropentyl Methacrylate, Pentadecafluorooctyl Methacrylate, Heptadecafluorodecyl Methacrylate, N,General-purpose (meth)acrylates can be used, such as polyalkylene oxide group-containing (meth)acrylic monomers including N-dimethyl(meth)acrylamide, acryloylmorpholine, (meth)acrylonitrile, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol-polypropylene glycol (meth)acrylate, polyethylene glycol-polybutylene glycol (meth)acrylate, polypropylene glycol-polybutylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol (meth)acrylate, lauroxypolyethylene glycol (meth)acrylate, stearoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and octoxypolyethylene glycol-polypropylene glycol (meth)acrylate.

[0030] Among (meth)acrylates, it is preferable that the main component be acrylate, preferably acrylate having an alkyl group having 1 to 20 carbon atoms, and preferably acrylate having an alkyl group having 1 to 12 carbon atoms.

[0031] Examples of acrylates having alkyl groups with 1 to 12 carbon atoms include methyl acrylate, ethyl acrylate, iso-propyl acrylate, allyl acrylate, n-butyl acrylate, iso-butyl acrylate, sec-butyl (meth)acrylate, tert-butyl acrylate, n-amyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, and n-lauryl (meth)acrylate. The (meth)acrylate used as a component of the styrene-acrylic copolymer may be one type or two or more types.

[0032] The styrene-acrylic copolymer may contain other known polymerizable compounds besides styrenes, (meth)acrylates, and (meth)acrylic acid as constituent components.

[0033] In copolymers of styrenes, (meth)acrylates, and (meth)acrylic acid, the proportion of styrenes may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 90% by mass or less, 80% by mass or less, or 70% by mass or less. Also, in copolymers of styrenes, (meth)acrylates, and (meth)acrylic acid, the proportion of (meth)acrylates may be 10% by mass or more, 15% by mass or more, 20% by mass or more, 80% by mass or less, 60% by mass or less, or 70% by mass or less. Also, in copolymers of styrenes, (meth)acrylates, and (meth)acrylic acid, the proportion of (meth)acrylic acid may be 10% by mass or more, 15% by mass or more, 20% by mass or more, 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0034] In an anionic styrene-acrylic copolymer, if it contains other known polymerizable compounds other than styrenes, (meth)acrylates, and (meth)acrylic acid, the proportion of the other polymerizable compounds in the styrene-acrylic copolymer is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0035] It is also preferable for the anionic styrene-acrylic copolymer to have nitrile groups. Specifically, for example, if the (meth)acrylate contains (meth)acrylonitrile, the styrene-acrylic copolymer can have structural units derived from acrylonitrile groups and can contain nitrile groups.

[0036] There are no particular limitations on the amount of anionic styrene-acrylic copolymer blended, but it may be 0.50% to 20% of the pulp mass, 1.0% to 20%, 1.5% to 20%, 2.0% to 20%, 2.5% to 20%, 3.0% to 20%, 0.50% to 15%, 0.50% to 10%, 0.50% to 9.0%, 0.50% to 8.0%, 0.50% to 7.0%, or 0.50% to 6.0%. From the viewpoint of preventing aggregation of internal additives, it may be 0.50% to 9.0%. From the viewpoint of further improving resistance to hot water, it may be 3.0% to 9.0%.

[0037] The structural units derived from acrylic acid may also be in the form of salts, such as sodium salts.

[0038] Anionic styrene-acrylic copolymers are available on the market, for example, in the form of aqueous dispersions.

[0039] (Anionic paraffin wax) The additives in the paper may further include anionic paraffin wax. The anionic paraffin wax can function as a water-resistant and oil-resistant agent.

[0040] Anionic paraffin wax is paraffin wax into which anionic functional groups have been introduced. Examples of anionic functional groups include carboxyl groups, sulfonic acid groups, and phosphate groups.

[0041] By including anionic paraffin wax, oil resistance can be further improved.

[0042] Anionic paraffin waxes are available on the market, for example, in the form of aqueous dispersions.

[0043] The melting point of the anionic paraffin wax is preferably in the range of 55°C to 130°C, and more preferably in the range of 80°C to 130°C.

[0044] There are no particular limitations on the amount of anionic paraffin wax to be blended, but it may be 0.50% to 20% of the pulp mass, 1.0% to 20%, 1.5% to 20%, 2.0% to 20%, 3.0% to 20%, 0.50% to 15%, 0.50% to 10%, 0.50% to 9.0%, 0.50% to 8.0%, 0.50% to 7.0%, or 0.50% to 6.0%. From the viewpoint of preventing aggregation of internal additives, it may be 0.50% to 9.0%. From the viewpoint of further improving oil resistance, it may be 2.0% to 9.0%.

[0045] There are no particular limitations on the ratio of the amount of anionic styrene-acrylic copolymer to the amount of anionic paraffin wax. For example, the ratio of the amount of anionic styrene-acrylic copolymer to the amount of anionic paraffin wax may be 0.10 or more and 10 or less, 0.20 or more and 10 or less, 0.50 or more and 10 or less, 0.70 or more and 10 or less, 1.0 or more and 10 or less, 1.5 or more and 10 or less, 2.0 or more and 10 or less, 0.10 or more and 6.0 or less, 0.10 or more and 4.0 or less, or 0.10 or more and 3.0 or less. From the viewpoint of further improving oil resistance, it may be 0.10 or more and 3.0 or less. From the viewpoint of further improving hot water resistance, it may be 0.70 or more and 3.0 or less.

[0046] (Other additives) Paper may contain other components. Examples of other components include additives such as silica, alumina, waxes other than anionic paraffin wax, defoamers, leveling agents, tackifiers, preservatives, antimicrobial agents, rust inhibitors, sizing agents, paper strength enhancers, yield enhancers, water filters, dyes, and pigments.

[0047] (Other properties of paper) In the wavenumber-transmittance graph based on FTIR analysis of the paper surface, at 3300 cm² -1 1730 cm relative to the height of the absorption peak in the vicinity -1Ratio of the height of the absorption peak in the vicinity (1730 cm -1 Peak height in the vicinity / 3300 cm -1 Value of the peak height in the vicinity) may be 0.15 or more and 0.60 or less, may be 0.20 or more and 0.60 or less, may be 0.30 or more and 0.60 or less, may be 0.15 or more and 0.50 or less, may be 0.15 or more and 0.46 or less, may be 0.15 or more and 0.44 or less, may be 0.15 or more and 0.40 or less. From the viewpoint of improving the smoothness of the paper surface, it is preferable that the ratio of the height of the absorption peak is 0.30 or more. From the viewpoint of preventing the aggregation of the internal additive, the ratio of the height of the absorption peak may preferably be 0.30 or more and 0.50 or less, more preferably 0.30 or more and 0.46 or less, and still more preferably 0.30 or more and 0.44 or less.

[0048] 1730 cm -1 The absorption peak in the vicinity corresponds to the vibration of the carbonyl group and may correspond to the amount of the anionic styrene-acrylic copolymer. 3300 cm -1 The absorption peak in the vicinity corresponds to the vibration of the hydroxyl group and may correspond to the amount of pulp (cellulose).

[0049] In the wavenumber-transmittance graph based on the FTIR analysis of the paper surface, 3300 cm -1 Ratio of the height of the absorption peak at 2915 cm to the height of the absorption peak in the vicinity -1 Ratio of the height of the absorption peak in the vicinity (2915 cm -1 Peak height in the vicinity / 3300 cm -1 Value of the peak height in the vicinity) may be 0.50 or more and 1.3 or less, may be 0.50 or more and 1.0 or less, may be 0.50 or more and 0.90 or less, may be 0.50 or more and 0.80 or less, may be 0.50 or more and 0.75 or less, may be 0.50 or more and 0.70 or less. From the viewpoint of improving the oil resistance, it is preferable that the ratio of the height of the absorption peak is 0.55 or more. From the viewpoint of preventing the aggregation of the internal additive, the ratio of the height of the absorption peak may preferably be 0.55 or more and 1.0 or less, more preferably 0.55 or more and 0.90 or less.

[0050] In the wavenumber-transmittance graph based on the FTIR analysis of the paper surface, 3300 cm -12850 cm relative to the height of the absorption peak in the vicinity -1 Ratio of the height of the absorption peaks in the vicinity (2850cm) -1 Nearby peak height: 3300cm -1 The value of the nearby peak height may be 0.40 or more and 1.2 or less, 0.40 or more and 1.0 or less, 0.40 or more and 0.80 or less, 0.40 or more and 0.75 or less, or 0.40 or more and 0.70 or less. From the viewpoint of improving oil resistance, it is preferable that the ratio of absorption peak heights is 0.45 or more. From the viewpoint of preventing aggregation of internal additives, the ratio of absorption peak heights may preferably be 0.45 or more and 0.80 or less, more preferably 0.45 or more and 0.75 or less, or more preferably 0.45 or more and 0.70 or less.

[0051] 2850cm -1 Nearby and 2915cm -1 The absorption peaks in the vicinity correspond to methylene vibrations and may correspond to the amount of anionic paraffin wax.

[0052] The paper surface measured by FTIR can be either a relatively smooth surface or a relatively rough surface.

[0053] The paper may be in a flat shape, or it may have a three-dimensional shape, i.e., pulp mold. The thickness of the paper is adjusted as appropriate depending on the application.

[0054] (Effects and Benefits) According to this embodiment, the paper contains a cationic polymer compound and an anionic styrene-acrylic copolymer as internal additives, resulting in excellent water resistance.

[0055] Furthermore, in the wavenumber-transmittance graph based on FTIR analysis of the paper surface, 3300 cm² -1 1730 cm relative to the height of the absorption peak in the vicinity -1 If the ratio of the heights of the surrounding absorption peaks is 0.30 or higher, the substance exhibits even greater resistance to hot water.

[0056] Furthermore, if the anionic styrene-acrylic copolymer contains nitrile groups, its smoothness is even better.

[0057] Furthermore, including anionic paraffin wax as an internal additive provides additional oil resistance.

[0058] The paper according to this embodiment is suitably applicable, for example, to food packaging materials.

[0059] (Paper manufacturing method) An example of a paper manufacturing method according to this embodiment will be described.

[0060] For example, when manufacturing flat-shaped paper, first, water, pulp, and the above-mentioned internal additives are stirred to obtain a pulp slurry. After letting the pulp slurry stand for at least one minute, papermaking and drying can be performed using a paper machine.

[0061] Furthermore, when manufacturing pulp molds, water, pulp, and the above-mentioned internal additives are similarly stirred to obtain a pulp slurry. After letting the pulp slurry stand for at least one minute, it is placed in a pulp mold and then dewatered and dried.

[0062] There are no particular limitations on the internal additives to be added to the pulp slurry, but they may be in liquid form, or in the form of a solution such as an aqueous solution, and are preferably in the form of an aqueous dispersion. [Examples]

[0063] The following ingredients were prepared.

[0064] Pulp: LBKP, NBKP, NUKP

[0065] Fixative ZeroRex RS1200: Hakuto: Polyvinylamine: Molecular weight 400,000 Lupasol HF:BASF:Polyethyleneimine:Molecular weight 25,000 Lupasol NW3:BASF:Polyethyleneimine:Molecular weight 340,000 Polymin SK: Hakuto: Polyethyleneimine: Molecular weight 2,000,000

[0066] Water and oil resistant agent A Cellosol 428: Chukyo Oils: Anionic paraffin wax EMUSTER-0135: Nippon Seiro: Anionic paraffin wax Cellosol H620: Chukyo Oils: Nonionic paraffin wax Joncryl wax26:BASF:PE wax

[0067] Water and oil resistant agent B Joncryl HPB1700:BASF:Anionic styrene-acrylic copolymer (containing structural units (nitrile groups) based on acrylonitrile): BASF:Tg 4℃:pH 7.5 Acronal S504: Anionic styrene-acrylic copolymer (containing structural units (nitrile groups) based on acrylonitrile): BASF: Tg 5℃: Particle size: 0.19μ: pH 7.0-8.0 Joncryl DFC3030: Anionic styrene-acrylic copolymer: BASF: Tg -27℃: pH 7.9: Acid value 64 Joncryl PDX7198: Anionic styrene-acrylic copolymer: BASF: Tg 14℃: pH 8.0: Acid value 36

[0068] (Manufacturing examples A1-A47: Paper manufacturing using a paper machine) LBKP pulp and NBKP pulp were weighed in a mass ratio of 80:20, torn into small pieces, mixed with water, and crushed for approximately 10 minutes using a mixer. The pulp was removed onto a cloth, the water was squeezed out, and it was torn into even smaller pieces. The obtained pulp was mixed with water to obtain a slurry with a pulp concentration of 3.0% by mass. Various internal additives were added to the slurry as shown in Tables 1 to 4 and stirred. After stirring, the mixture was allowed to stand for at least 1 minute. Then, using the slurry, wet paper was obtained by passing it through a sieve using a paper machine. The wet paper was dewatered by applying pressure, and then dried to obtain the papers of Production Examples A1 to A47.

[0069] The basis weight is 100g / m². 2 The drying conditions were 80-100°C for 10 minutes (on a plate).

[0070] (Manufacturing examples B1-B6: Manufacturing of pulp molds using a pulp molding machine) NUKP pulp was mixed with water and beaten using a beater. The beaten pulp was given a slurry by adjusting the water content to a concentration of 0.7% by mass. Various internal additives were added to the slurry as shown in Table 5 and stirred. After stirring, the slurry was allowed to stand for at least 1 minute. Then, using a pulp molding machine, the slurry was strained through a mesh mold to obtain a wet pulp mold. The wet pulp mold was then dried by heating while applying pressure from both sides to dewater it, to obtain cup-shaped pulp molds for production examples B1 to B6.

[0071] The density of the pulp mold after drying is 0.5 g / cm³. 3 That's what I decided.

[0072] (evaluation) Table 6 shows the evaluation methods for water resistance, hot water resistance, oil resistance, smoothness, and coagulation of paper and pulp molds obtained from a paper machine. The surface evaluated for smoothness was the screen surface in the case of a paper machine, and the surface opposite the screen in the case of a pulp molding machine; both surfaces were relatively dense and smooth.

[0073] (FTIR measurement of the surface) The surface of paper and pulp mold obtained from the paper machine was analyzed by FTIR, with the horizontal axis representing wavenumber (cm²). -1 ), a graph was obtained with the vertical axis representing transmittance (%).

[0074] The method for calculating the peak height is as follows: In the FTIR measurement result graph, the downward-sloping absorption peak was identified, and the absolute value of the transmittance of the identified peak was subtracted from 100.

[0075] The absorption peak is at 1730 cm. -1 Nearby, 2850cm-1 , 2915cm -1 , 3300cm -1 They were identified in the vicinity.

[0076] 1730cm -1 Nearby peak height: 3300cm -1 The nearby peak heights are set to P1730 / P3300, resulting in a total height of 2850 cm. -1 Nearby peak height: 3300cm -1 The nearby peak heights are set to P2850 / P3300, resulting in a height of 2915 cm. -1 Nearby peak height: 3300cm -1 The nearby peak heights are set to P2915 / P3300 and are shown in the table.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] [Table 4]

[0081] [Table 5]

[0082] [Table 6]

[0083] For example, while the water resistance and hot water resistance of production examples A2 and A4 were the same as those of production example A1, production example A7, which was a combination of the internal additives of production examples A2 and A4, exhibited superior water resistance and other properties compared to production example A1, confirming the synergistic effect of the combination of cationic polymer compounds and anionic styrene-acrylic copolymers.

[0084] Furthermore, in the wavenumber-transmittance graph based on FTIR analysis of the paper surface, 3300 cm² -1 1730 cm relative to the height of the absorption peak in the vicinity -1 When the ratio of the heights of the surrounding absorption peaks was 0.30 or higher, the material exhibited excellent heat and water resistance, and when the anionic styrene-acrylic copolymer contained nitrile groups, it exhibited excellent smoothness.

[0085] Furthermore, the addition of anionic paraffin wax improved oil resistance.

Claims

1. Paper comprising pulp and an additive, wherein the additive comprises a cationic polymer compound and an anionic styrene-acrylic copolymer.

2. In the wavenumber-transmittance graph based on FTIR analysis of the surface of the aforementioned paper, at 3300 cm² －１ 1730 cm relative to the height of the absorption peak in the vicinity －１ The paper according to claim 1, wherein the ratio of the heights of the nearby absorption peaks is 0.30 or more.

3. The paper according to claim 1 or 2, wherein the cationic polymer compound is an aqueous polymer compound.

4. The paper according to claim 1 or 2, wherein the cationic polymer compound is at least one selected from the group consisting of polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, cationic epoxy resin, cationized starch, polyamino acid, melamine resin, polyacrylamide, polyvinylpyridine, polyvinylimidazole, polyguanidine, polyamino ester, and polydimethyldiallylammonium chloride.

5. The paper according to claim 1 or 2, wherein the molecular weight of the cationic polymer compound is 25,000 or more.

6. The paper according to claim 1 or 2, wherein the anionic styrene-acrylic copolymer has a nitrile group.

7. The paper according to claim 1 or 2, wherein the internal additive further comprises anionic paraffin wax.

8. In the wavenumber-transmittance graph based on FTIR analysis of the surface of the aforementioned paper, at 3300 cm² －１ 2915 cm relative to the height of the absorption peak in the vicinity －１ The paper according to claim 7, wherein the ratio of the heights of the nearby absorption peaks is 0.55 or greater.

9. The paper according to claim 1 or 2, which is a pulp mold.

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