JP6778041B2 - Water repellent for paper and paper manufacturing method - Google Patents

Description

The present invention relates to a water repellent for paper and a method for producing paper.

Paper such as wrapping paper and paperboard such as corrugated cardboard are surface-treated with a water-repellent agent for paper for the purpose of quality preservation of contents during transportation, safe transportation, prevention of strength deterioration due to moisture, etc. (Patent Document 1 etc.).

JP 2011-117107

In recent years, the composition of raw materials for paperboard has changed, and the composition ratio of used paper having a high content of fillers and fine fibers has increased. Along with this, the surface characteristics of the paperboard have changed, and even if a water-repellent agent is applied to the paperboard having a high mixing ratio of used paper, a sufficient water-repellent effect cannot be obtained by itself.

Specifically, for example, in the production of corrugated cardboard, the water repellent is melted by the drying step immediately after the water repellent coating or the heat when the core base paper is attached to the paperboard coated with the water repellent. The water repellency decreases as this penetrates into the voids between the pulp fibers. The more the amount of used paper is, the more likely the water repellency is to decrease.

Further, when printing on a paperboard treated with a water repellent agent, if the amount of the water repellent agent treated is too large (the water repellency is too strong), the water-based ink may be repelled. The water-based ink that cannot be instantly permeated into the paperboard may adhere to parts other than the printed portion and equipment, and eventually stain the printed surface, leading to printing defects. On the other hand, by reducing the amount of the water repellent treatment, the permeability of the water-based ink is improved and the printing defect is improved, but the water repellency is naturally lowered.

Therefore, an object of the present invention is to provide a water repellent for paper capable of achieving both high water repellency and low ink contamination, and a method for producing paper using the same.

In order to achieve the above object, the water repellent for paper of the present invention contains a polymer containing a vinyl-based monomer having a long-chain alkyl group as a polymerization component, and has the length of the vinyl-based monomer. The chain alkyl group is characterized by having 14 or more carbon atoms.

The method for producing paper of the present invention is characterized in that the surface of the paper is water-repellent-treated with the water-repellent agent for paper of the present invention.

According to the present invention, it is possible to provide a water repellent for paper capable of achieving both high water repellency and low ink contamination, and a method for producing paper using the same.

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

As a polymer-type water-repellent component, the present inventors emulsified a polymer mainly composed of a vinyl-based monomer having a long-chain alkyl group in a side chain, and treated the polymer with a water-repellent treatment with the obtained water-repellent agent. We arrived at the present invention by paying attention to the fact that the water repellency of paper does not easily decrease even when it is stored in a high temperature environment for a long time. Since the water repellent for paper of the present invention is excellent in water repellency, for example, high water repellency can be obtained even with a low treatment amount. Therefore, for example, it is possible to achieve both improvement of stains on the printed surface during the printing process and heat and water repellency.

The composition ratio of the vinyl-based monomer having a long-chain alkyl group is, for example, 80 to 100% by weight or 90 to 100% by weight with respect to the total amount of the monomer units constituting the polymer.

The vinyl-based monomer having a long-chain alkyl group contains, for example, at least one of acrylate and methacrylate. The acrylate and methacrylate are preferably the main components of the vinyl-based monomer. The "main component" includes, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight of the acrylate and methacrylate with respect to the total amount of the vinyl-based monomer. It means that it is weight% or more.

In the method for producing paper of the present invention, for example, printing may be performed on the surface after the water-repellent treatment.

In the method for producing paper of the present invention, for example, the paper may be paperboard.

[1. Water repellent for paper]
Next, examples of the components of the water repellent for paper of the present invention will be described.

(1) Water-Repellent Polymer As described above, the water-repellent agent for paper of the present invention contains a vinyl-based monomer having a long-chain alkyl group as a polymerization component, and is a vinyl-based single amount having the long-chain alkyl group. It is characterized by containing a polymer having 14 or more carbon atoms in the alkyl group of the body (hereinafter, may be referred to as "water-repellent polymer"). The vinyl monomer is preferably the main polymerization component of the water-repellent polymer. In the present invention, the "polymerization component" of the polymer is a monomer unit of the polymer, and the "main polymerization component" is, for example, 50% by weight based on the total amount of the monomer units constituting the polymer. The above is a monomer unit of 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. Examples of the vinyl-based monomer having a long-chain alkyl group include vinyl-based monomers represented by the following chemical formula (1) or (2).

In the chemical formulas (1) and (2), X is H or CH ₃ . Further, R ₁ and R ₂ are linear or branched alkyl groups having 14 to 24 carbon atoms, respectively, and are preferably linear alkyl groups having 14 to 24 carbon atoms, respectively.

In the chemical formula (1), the monomer in which X = H and R ₁ is C ₁₈ H ₃₇ (straight chain, stearyl group) represents stearyl acrylate.

In the chemical formula (1), the monomer having X = CH ₃ and R ₁ being C ₁₈ H ₃₇ (straight chain, stearyl group) represents stearyl methacrylate.

In the chemical formula (2), the monomer having X = H and R ₂ being C ₁₅ H ₃₁ (linear, pentadecyl group) represents vinyl palmitate.

When the vinyl-based monomer is not blended, or when the alkyl group of the vinyl-based monomer has a carbon number shorter than 14, the water repellency of the water repellent using the polymer becomes low. The upper limit of the number of carbon atoms of the alkyl group of the vinyl-based monomer is not particularly limited, but is, for example, 24 or less. Further, the number of carbon atoms of the alkyl group of the vinyl-based monomer is more preferably 14 to 22.

In the water-repellent agent for paper of the present invention, the water-repellent polymer may be a homopolymer composed only of a vinyl-based monomer having a long-chain alkyl group (the alkyl group has 14 or more carbon atoms), or another monomer. It may be a copolymer (copolymer) with. In the case of a copolymer, it may be a block copolymer or a random copolymer. Further, the other monomer is not particularly limited. As described above, the composition ratio of the vinyl-based monomer having a long-chain alkyl group is 80 to 100% by weight or 90 to 100% by weight with respect to the total amount of the monomer units constituting the water-repellent polymer. This is preferable from the viewpoint of water repellency.

The method for producing the water-repellent polymer is not particularly limited, and for example, it can be produced (synthesized) by a known polymerization method.

(2) Other Components The water-repellent agent for paper of the present invention may or may not contain components other than the water-repellent polymer as appropriate. The other components are not particularly limited, but are as follows, for example.

The other component may include, for example, water. The water-repellent agent for paper of the present invention may be in a state in which the water-repellent polymer is dispersed (emulsified) in water, for example. The water content is not particularly limited, but is, for example, 50% by weight or more, for example, 80% by weight or less, based on the total weight of the water repellent for paper of the present invention.

The other component may contain, for example, paraffin (paraffin wax). By blending paraffin, for example, emulsion stability is further improved. The paraffin (paraffin wax) is not particularly limited, and examples thereof include normal paraffin, isoparaffin, cycloparaffin, and oxidized paraffin. Further, in addition to or in place of the paraffin (paraffin wax), another wax may be used. Examples of the other waxes include natural waxes such as carnauba wax, candelilla wax, montan wax, ceresin, and microcrystalline wax, and long-chain alkyl esters such as beef fat hardening oil, stearyl stearate, and pentaerythritol tetrastearate. Can be mentioned. These waxes may be used alone or in combination of two or more. The amount of the wax used is not particularly limited, but the weight of the water-repellent polymer is, for example, 30% by weight or more, or 50% by weight or more, based on the total weight of the water-repellent polymer and the wax. , 100% by weight or less, or 90% by weight or less.

The other component may include, for example, a petroleum resin. By including the petroleum resin, for example, the water repellency and emulsion stability of the water repellent for paper are further improved. In the present invention, the petroleum resin is, for example, an aliphatic petroleum resin, an aromatic petroleum resin, an alicyclic petroleum resin, or a mixed petroleum resin thereof, and maleic anhydride, maleic anhydride, and the like. Examples thereof include resins anion-modified with dibasic acids such as fumaric acid and itaconic acid. Examples of the aliphatic petroleum resin include petroleum resins obtained from butene, isobutene, pentene, pentadiene, isopropylene and the like. Examples of aromatic petroleum resins include petroleum resins obtained from indene, methyl inden, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, kumaron-indene and the like. Examples of the alicyclic petroleum resin include petroleum resins obtained from monomers such as cyclopentadiene and dicyclopentadiene. In addition, in the present invention, examples of the petroleum resin include rosin resins (gamrosin, rosin ester, rosin derivative), terpene resins and the like. Examples of the rosin-based resins include rosins such as gum rosin, wood rosin and tall oil rosin, resins obtained by anion-modifying these with dibasic acids such as maleic acid, maleic anhydride, fumaric acid and itaconic acid, and rosin esters. Examples thereof include hydrogenated rosin and hydrogenated rosin ester. Examples of the terpene resin include α-pinene resin, β-pinene resin, and aromatic-modified terpene resin obtained by copolymerizing terpenes such as α-pinene and β-pinene with an aromatic monomer such as styrene. And so on. These petroleum resins may be used alone or in combination of two or more. The amount of the petroleum resin used is not particularly limited, but the weight of the petroleum resin is, for example, 50% by weight or more or 60% by weight or more with respect to the total weight of the water-repellent polymer, the wax, and the petroleum resin. For example, 85% by weight or less, or 80% by weight or less.

The other component may contain, for example, a fatty acid. By containing a fatty acid, for example, the salt of the fatty acid acts as an emulsifier, and an effect of contributing to the improvement of emulsion stability can be obtained. The fatty acid is not particularly limited, and examples thereof include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, and only one type or a plurality of types may be used in combination. The amount of the fatty acid used is not particularly limited, but is, for example, 0% by weight or more, or 5% by weight or more, and for example, 25% by weight or less, or 15% by weight or less, based on the weight of the water-repellent polymer. ..

The other component may contain, for example, an emulsifier. The emulsifier is not particularly limited, and examples thereof include a nonionic surfactant and an anionic surfactant, and only one type or a plurality of types may be used in combination. Examples of the nonionic surfactant include POE alkyl ether types such as polyoxyethylene (POE) stearyl ether and POE oleyl ether, and POE fatty acid ester types such as POE monostearate and POE sorbitan monolaurate. Can be mentioned. Examples of the anionic surfactant include a carboxylate type, a sulfate ester type, a sulfonate type, and a phosphoric acid ester type. The amount of the emulsifier used is not particularly limited, but is, for example, 0% by weight or more, or 15% by weight or more, for example, 60% by weight or less, and 45% by weight, based on the weight of the water-repellent polymer. It is as follows.

The other component may contain, for example, a base. By containing a base, for example, the effect that the base forms a salt with the fatty acid and acts as an emulsifier can be obtained. The base may be an inorganic base or an organic base, and only one type or a plurality of types may be used in combination. Examples of the inorganic base include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Examples of the organic base include alkanolamines such as triethanolamine, diethanolamine and monoethanolamine, morpholine and aminoalcohol.

The method for producing the water repellent for paper of the present invention is not particularly limited, but for example, it can be produced by mixing all the above components and emulsifying them.

[2. Water-repellent treated paper]
As described above, the method for producing paper of the present invention is characterized in that the surface of the paper is water-repellent-treated with the water-repellent agent for paper of the present invention. This makes it possible to produce the paper of the present invention whose surface is water-repellent treated with the water-repellent agent for paper of the present invention. Further, as described above, in the method for producing paper of the present invention, for example, printing may be performed on the surface after the water-repellent treatment. As a result, it is possible to further produce paper printed on the surface after the water-repellent treatment.

Further, in the present invention, the "paper" may be a paperboard as described above. In the present invention, "paperboard" refers to thick paper. The thick paper may be, for example, a paper formed by laminating a plurality of sheets of paper. In the present invention, the "paper" is not particularly limited, and examples thereof include wrapping paper, newspaper, books / magazines, and copy paper. In the present invention, the "paperboard" is not particularly limited, and examples thereof include corrugated cardboard, paper boxes / paper containers, and base paper for building materials.

The use of the water repellent for paper of the present invention is not particularly limited, and any paper may be used. However, according to the water repellent for paper of the present invention, as described above, it is possible to achieve both high water repellency and low ink contamination. Therefore, the water-repellent agent for paper of the present invention is particularly suitable for a water-repellent treatment before printing on paper whose surface is to be printed.

The method of the water-repellent treatment is not particularly limited, but for example, the water-repellent agent for paper of the present invention may be applied to the surface of paper or paperboard and dried. The amount of the water repellent for paper of the present invention applied to the surface of the paper or paperboard is not particularly limited, but is, for example, 0.05 g / m ² in terms of the weight of the solid content in the water repellent for paper. Or more, or 0.2 g / m ² or more, for example, 3 g / m ² or less, or 1.5 g / m ² or less. The "solid content" in the water repellent for paper of the present invention refers to, for example, all the components of the water repellent for paper of the present invention excluding water. The drying temperature is not particularly limited, but is, for example, 80 to 160 ° C. or 100 to 140 ° C., and the drying time is not particularly limited, but is, for example, 10 seconds to 10 minutes, or 30 seconds to 5 minutes. The printing method is not particularly limited, and for example, general flexographic printing, offset printing, gravure printing, or the like may be used, but flexographic printing is particularly preferable.

Next, examples of the present invention will be described. However, the present invention is not limited to the following examples.

1. 1. Method for producing water repellent (1) Method for polymerizing water repellent polymer (solution polymerization)
・ Synthesis example 1
A flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer was charged with 100 parts by weight of behenyl acrylate and 100 parts by weight of toluene. Oxygen in the reaction system was sufficiently replaced with nitrogen, and then the mixture was heated to 70 ° C., and then 0.3 parts by weight of the radical polymerization initiator AIBN dissolved in a small amount of toluene was added to the reaction vessel. Then, the polymerization reaction was allowed to proceed for 8 hours in a temperature range of 75 to 80 ° C. After completion of the reaction, the mixture was cooled to room temperature to obtain polymer A, which is a water-repellent polymer.

-Synthesis examples 2 to 10
The monomers used were prepared in the same manner as in Synthesis Example 1 except that the monomer types and ratios shown in Table 1 below were changed, and polymers B to J, which are water-repellent polymers, were obtained as polymers.

(2) Measurement of molecular weight of polymer For the polymers A to J obtained in Synthesis Examples 1 to 10, the weight average molecular weight was determined by using the analysis module Waters e2695, detector Waters 2414, and data processing Emper2 software (trade name) manufactured by Waters Corp. Was measured.

(3) Manufacturing Method of Water Repellent / Example 1
9 parts by weight of the polymer A from which the solvent component has been removed by heating, 2 parts by weight of paraffin wax (trade name "Pervan 1320", manufactured by ExxonMobil Co., Ltd.), petroleum resin (trade name "Quinton D-200", Nippon Zeon Co., Ltd.) 13 parts by weight made by the company, product name "Haritac 4740", 6 parts by weight made by Harima Kasei Co., Ltd.) 19 parts by weight, mixed fatty acid (trade name "Nu fatty acid", manufactured by Tsukino Food Industry Co., Ltd.) 0.6 parts, emulsifier (Product name "Brownon SR-706" POE stearyl ether (EO = 6 mol), manufactured by Aoki Oil & Fat Industry Co., Ltd.) 2.0 parts, 48% potassium hydroxide aqueous solution 1.3 parts by weight, triethanolamine 1.3 parts by weight The parts were mixed and heated to 90 to 95 ° C. and mixed uniformly. Next, 64.8 parts by weight of pre-boiled warm water was gradually added at a flow rate of 3 g / min to carry out phase inversion emulsification for 20 minutes, and then cooled to room temperature to add a water repellent (water repellent composition). Obtained.

-Examples 2 to 9
A water repellent composition was obtained by emulsifying in the same manner as in Example 1 except that the polymers B to H were used instead of the polymer A.

Example 10
A water repellent composition was obtained by emulsifying in the same manner as in Example 1 except that 11 parts by weight of polymer C was used instead of using polymer A and paraffin wax.

・ Comparative example 1
A water repellent composition was obtained by emulsifying in the same manner as in Example 1 except that 11 parts by weight of paraffin wax was used without using a polymer.

・ Comparative example 2
A water repellent composition was obtained by emulsifying in the same manner as in Example 1 except that the polymer J was used instead of the polymer A.

-Examples 11 to 13
A water repellent composition was obtained by emulsifying in the same manner as in Example 4 except that the blending amounts of the polymer D and paraffin were changed.

-Examples 14 to 15
A water repellent composition was obtained by emulsifying in the same manner as in Example 4 except that the blending amounts of polymer D, paraffin and petroleum resin were changed.

2. Evaluation of ink contamination (1) Method for producing test piece treated with water repellent agent So that the amount of water repellent treated is 0.2 g / m ² (= weight of water repellent solid content per liner unit area). A water repellent was applied to a liner (cardboard) having a basis weight of 280 g / m ^{2 with} a glass rod, and then dried in a circulation dryer at 120 ° C. for 1 minute to obtain a water repellent liner (paper of the present invention).

(2) Evaluation method of ink contamination The above water-repellent treatment test piece was coated with an 87.5% aqueous solution of black water-based flexo ink (trade name "FK-Flemio DF-260 Black", manufactured by Sakata Inx Corporation) at Meyerbar No. After coating with No. 12, white coated paper was attached to the ink coated surface after 10 seconds and crimped with a load of 5 kg, and ink stains on the white coated paper surface when peeled from the test piece were visually confirmed. The evaluation results were evaluated on a three-point scale of ○ △ × as shown below.

◯: Equivalent to the ink stain state on the test piece not treated with water repellent treatment (there is almost no ink stain)
Δ: It is more dirty than the ink stain state on the test piece not treated with water repellent treatment ×: It is significantly dirty than the ink stain state on the test piece not treated with water repellent treatment

3. 3. Water repellency evaluation (1) Manufacturing method of water repellent paper After applying a water repellent to a liner with a basis weight of 280 g / m ^{2 with} a glass rod so that the water repellent treatment amount is 0.2 g / m ² . A water-repellent paper was obtained by drying in a circulation dryer at 120 ° C. for 1 minute.

(2) Water-repellent evaluation method The water-repellent paper produced by the above method was heat-treated in a circulation dryer set at 160 ° C. for 30 minutes, and then subjected to a water-repellent evaluation test. This is because, in the case of industrial mass production of a water-repellent liner treated with a water-repellent finish, heat tends to be trapped inside the roll when it is wound up and stored, so that state is reproduced. After the heat treatment, Japan TAPPI pulp and paper test method No. The water repellency was measured according to the method specified in 68: 2000. Specifically, the water-repellent paper prepared by the above method was tilted at 45 °, ion-exchanged water was dropped from a place 10 mm apart in the vertical direction (1 drop: about 0.1 ml), and traces of flow were observed. .. The water repellency was evaluated by R0 to R10 according to the evaluation criteria in Table 2 below. The water repellency with the lowest number after R (eg R0) has the lowest water repellency, and the water repellency with the highest number after R (eg R10) has the highest water repellency. R7 or higher has good water repellency.

Tables 3 to 7 below show the compositions of the water repellents (water repellent compositions) of Examples 1 to 15 and Comparative Examples 1 and 2 together with the evaluation results of ink stain property and water repellency.

As shown in Tables 3 to 7, in Examples 1 to 15, the water repellency was in the range of R7 to R10 and the ink stain property was ◯, and good results were obtained in each case. Regarding water repellency, as described above, high water repellency was obtained because the heat resistance of the water repellent film was high despite the long heat treatment at a high temperature of 160 ° C. for 30 minutes. On the other hand, in Comparative Examples 1 and 2, the water repellency was R6 or R6-7, which was inferior to that of the examples, and the ink contamination property was Δ, which was poor.

Table 5 shows the results of examples in which the composition ratios of the water-repellent polymer and paraffin were changed (Example 3, Example 9, and Comparative Example 1). As shown in the table, Examples 3, 10, and Comparative Example 1 have the same composition except that the amounts (parts by weight) of the water-repellent polymer (polymer C) and paraffin used are different. As shown in the table, in Example 3 in which 2.0 parts by weight of paraffin was added and in Example 10 in which paraffin was not added, both high water repellency and low ink contamination were similarly achieved. On the other hand, in Comparative Example 1 in which 11.0 parts by weight of paraffin was added and no water-repellent polymer was added, the water repellency was poor at R6 and the ink stain property was poor at Δ. Further, in Comparative Example 2, since the monomer (lauryl acrylate) constituting the polymer J has a small number of alkyl carbon atoms of 12, as described above, the water repellency is R6-7, which is inferior to that of the examples, and the ink stain property. Was also bad with △.

In addition, Table 6 shows another example (Examples 4, 11, 12 and 13) in which the composition ratios of the water-repellent polymer and paraffin were changed. As shown in the table, Examples 4, 11, 12 and 13 have the same composition except that the amounts (parts by weight) of the water-repellent polymer (polymer D) and paraffin used are different. As shown in the table, good water repellency was obtained in all the examples, but the polymer / (polymer + paraffin) ratio (weight ratio of water-repellent polymer to total weight of water-repellent polymer and paraffin wax) was high. The higher the water repellency was obtained.

Table 7 shows examples in which the petroleum resin / (petroleum resin + polymer + paraffin) ratio (weight ratio of petroleum resin to the total weight of the water-repellent polymer, paraffin wax, and petroleum resin) was changed (Examples 14 and 4). And 15) are shown. As shown in the table, Examples 14, 4 and 15 have the same composition except that the amounts (parts by weight) of the water-repellent polymer (polymer D) and the petroleum resin used are different. As shown in the table, good water repellency was obtained in all the examples, but the higher the petroleum resin / (petroleum resin + polymer + paraffin) ratio, the higher the water repellency tended to be. The reason for this is not clear, but it is presumed that the emulsification stability was further improved. It should be noted that the water repellency was inferior when the water repellent polymer was not added (Comparative Example 1), as shown in Tables 4 and 5.

As shown in Table 3 above, in the monomers constituting the water-repellent polymer, Example 2 in which the linear C18 acrylate homopolymer was used and Example 3 in which the branched C18 acrylate was used were both repellent in the same manner. It was confirmed that the water content was extremely high.

Claims (8)

A polymer containing a vinyl-based monomer having a long-chain alkyl group as a polymerization component , an emulsifier, a wax, and a petroleum resin are contained, and the carbon number of the long-chain alkyl group of the vinyl-based monomer is A water repellent for paper characterized by being 14 or more. The water repellent for paper according to claim 1, wherein the weight of the petroleum resin is 50% by weight or more and 85% by weight or less with respect to the total weight of the polymer, the wax and the petroleum resin. The water repellent for paper according to claim 1 or 2, wherein the weight of the polymer is 30% by weight or more and 90% by weight or less with respect to the total weight of the polymer and the wax. The paper according to any one of claims 1 to 3 , wherein the composition ratio of the vinyl-based monomer in the polymer is 80 to 100% by weight with respect to the total amount of the monomer units constituting the polymer. Water repellent for use. The water repellent for paper according to any one of claims 1 to 4, wherein the vinyl-based monomer contains at least one of acrylate and methacrylate. A method for producing a water-repellent treated paper, which comprises treating the surface of the paper with the water-repellent agent for paper according to any one of claims 1 to 5 . The manufacturing method according to claim 6 , further comprising printing on the surface after the water-repellent treatment. The manufacturing method according to claim 6 or 7 , wherein the paper is paperboard.