JP4311998B2 - Oil resistant paper - Google Patents

Description

  The present invention relates to an oil-resistant treated paper (oil-resistant paper) prepared using a base paper or paperboard as a base material, and particularly, an oil-resistant treated paper having a structure suitable for production by oil-resistant treatment using a size press or an off-coater. And a manufacturing method thereof.

Conventionally, paper-based products are often used as product packaging materials in the food field, particularly in the field of fast food. Since there are many foods that contain oil in this field, using paper that does not have oil resistance causes the problem that the oil contained in the food penetrates into the paper over time and oozes out of the packaging. To do. Therefore, a surface treatment agent called an oil resistance agent is applied to the paper surface at a solid content (film forming element) application amount: 0.1 to 0.5 g / m ² to prevent oil penetration. I have been.

  As a paper surface treatment agent for the purpose of imparting oil resistance, a fluorine-based emulsion type coating agent is generally used. However, there is a concern that fluorine chemicals may cause ozone layer destruction in the atmosphere directly or indirectly from the viewpoint of the impact on the global environment in recent years. In addition, carcinogenic problems have been pointed out in the process of producing fluorine chemicals, and surface treatment agents that are more friendly to the environment and the human body are being required.

  For example, Patent Documents 1 to 3 exist as coating agents (surface treatment agents) that impart oil resistance to the paper surface without using fluorine chemicals.

Patent Document 1 discloses a paper sizing agent using a dicarboxylic acid starch ester as a base, and Patent Document 2 discloses an oil-resistant paper in which a clay coat layer is formed on a base paper and an oil-resistant layer is formed thereon. Describes oil-resistant paper in which starch modified with hydrophobic properties (alkyl dicarboxylic acid starch ester; octenyl succinic acid starch ester, etc.) is applied to the base paper.
Japanese Patent Application Laid-Open No. 55-107598 JP 2002-38398 A JP 2002-69889 A

  In view of the above, an object of the present invention is to provide a new oil-resistant agent and an oil-resistant treated paper using the same that do not adversely affect the environment and do not cause problems such as carcinogenicity in the production process. (Problem).

  A specific problem is that oil-resistant treated paper (oil-resistant paper) is used in direct contact with foods, so there are many uses, so that there is no adverse effect on the human body, that is, as a food or food additive, A highly water-repellent / water-resistant resin with high safety that can be adapted to those uses, and a non-modified starch or modified starch (starch derivative) that is used as food and highly safe, It is to provide an oil-resistant treated paper.

  The oil-resistant paper according to the present invention solves the above-described problems by the following configuration.

An oil-resistant layer is provided on one or both sides of the paper substrate,
Each of the oil-resistant treatment layers includes an undercoat film (undercoat) and a topcoat film (topcoat) by applying a paste liquid,
The top coating film is composed mainly of a decomposed starch selected from oxidized starch or acid-treated starch, or a starch derivative of a hydroxylated hydrogen-substituted product of the decomposed starch,
The undercoat coating is a mixture of the former / the latter (solid weight ratio) = 5/95 to 95/5 with elastomeric aqueous colloid and gelatinized possible starches characterized in that it is a coating film mainly composed.

  The top coat film in the present invention is based on low-viscosity starch, whereby starch can be gelatinized at a high concentration, and the film-forming ability on a paper substrate can be increased.

  Furthermore, by replacing and blocking the hydroxyl hydrogen of the starch polymer of the low-viscosity starch, in addition to the film forming ability, it is possible to impart anti-aging and thickening resistance and appropriate water resistance.

  The undercoating film is made of a mixture of gelatinizable starch and an elastomer water-based colloid or a water-retaining / water-absorbing polymer as a main component of the coating film, whereby the bending resistance of the topcoat is improved. It is estimated that brittleness, which is an inherent characteristic of starch polymers, is reduced for the following reasons.

  In the case of an elastomer aqueous colloid, the elastomer particles (colloid) are dispersed between starch polymers to give flexibility. In the case of a water-absorbing / water-retaining polymer, the water content of the starch polymer is moderately maintained to maintain flexibility.

  In the case of the elastomer aqueous colloid, rubber latex can be preferably used.

  The hydroxyl hydrogen-substituted product is usually an esterified starch or an etherified starch.

As the esterified starch,
(a) an acyl residue substitution product of a saturated or unsaturated fatty acid having 2 to 16 carbon atoms and an aromatic carboxylic acid, and having a hydroxyl group substitution degree (DS) of about 0.001 to 1.8,
(b) A monoacyl residue substitution product (single esterification product) of a succinic acid, maleic acid or a derivative thereof having an alkyl / alkenyl modifying group having 1 to 26 carbon atoms, and a hydroxyl group substitution degree (DS) of about 0 .001-0.5,
Can be suitably used.

  In addition, the etherified starch is a hydroxyalkylated product of ethylene oxide, propylene oxide, or mono-diglycidyl ether of mono- or divalent alkyl alcohol having 1 to 8 carbon atoms in total, and the degree of molecular substitution (MS ) Of about 0.01 to 0.5 can be suitably used.

  In the above configuration, it is desirable to further add a hygroscopic mineral salt to at least the top coat film. By adding the hygroscopic mineral salt, the permeability of the starch polymer to the paper base is promoted, and the oil resistance of the starch polymer is imparted to the paper base, resulting in the oil resistance of the oil-resistant treated paper. Improves.

  In each of the above structures, it is preferable that at least the top coat film further contains an inorganic filler. This is because the print setability can be improved.

In general, the oil-resistant paper of the present invention has a basis weight of 400 g / m ² or less in each of the above-described configurations, and each coating film forming component amount in the undercoat film and the topcoat film is 0.1. it is desirable to to 20 g / ^{m 2.}
Moreover, the manufacturing method of the oil-resistant paper of this invention becomes the following structure.

Elastomeric aqueous colloidal former / the latter (weight ratio) between de and gelatinized possible starch = about 5/95 to 95/5 undercoating paint auxiliary materials necessary to glue liquid of the mixture was added of to the paper substrate After applying and forming the undercoat film,
A top coating film is formed by applying a top coating film to which an auxiliary material is added if necessary to the gelatin solution of the gelatinizable starch on the under coating film, and further dried.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the present specification, “parts”, “%” and the like representing the blend are mass units and are based on the dry state.

  The oil-resistant treated paper of the present invention is provided with the oil-resistant treated layer 14 on one side or both sides (one side in the illustrated example) of the paper base 12.

Here, the paper base material to be subjected to the oil resistance treatment (oil resistance imparting treatment) is not particularly limited regardless of whether it is a paper paper or a paperboard. Usually, a basis weight of 400 g / m ² or less, preferably a paper substrate of about 300~25g / m ^2. When the basis weight is too large, the refractive part elongation at the time of bending exceeds the elongation of the coating film.

  In addition, in the paper manufacturing process, polyacrylamide and various waxes are added internally or externally in advance in the paper manufacturing process, and the wet physical properties (wet strength, water absorption, etc.) of the base paper are finally used. It may be raised to the required level for

  The oil-resistant treatment layer 14 includes an undercoat film (undercoat) 16 and a topcoat film (topcoat) 18 by applying a glue solution, respectively.

Here, the amount of each coating film forming component of the undercoat film 16 and the topcoat film 18 varies depending on the type and thickness of the paper base material, required oil resistance, etc., but is usually 0.1 to 20 g / m. ²
Desirably, the amount is about 0.5 to 15 g / m ² .
In the top coat film, low-viscosity starch (decomposed starch) or a hydrolyzable hydroxyl hydrogen-substituted product of the decomposed starch is a coating film main component (coating film forming component).

  Here, the low-viscosity starch is usually oxidized starch or acid-treated starch, and the viscosity of the paste solution having a solid content of 8% at 50 ° C. is about 0.01 to 4 Pa · s, preferably about 0.05 to 0.4 Pa.・ As s. If the decomposition level is too low (when the viscosity is too high), surface treatment with a high-concentration paste is difficult. Conversely, if the decomposition level is too high (if the viscosity is too low), the coating strength and good formability are achieved. It becomes difficult to obtain.

  Here, the raw material starch is not particularly limited, and ground starch such as wheat starch and corn starch, underground starch such as potato starch, tapioca starch, sweet potato starch and sago starch, and composites thereof can be used. Of these, underground starch is preferred because it can be obtained with a relatively high viscosity.

  Oxidized starch and acid-treated starch can use oxidizing agents such as sodium hypochlorite, potassium permanganate, and hydrogen peroxide, and organic acids or inorganic acids such as sulfuric acid, acetic acid, hydrochloric acid, and phosphoric acid. is there.

  The hydroxyl hydrogen-substituted product is usually an esterified starch or an etherified starch.

  The esterified starch (acyl residue substitution product) is not particularly limited, and may be an acyl residue substitution product of sulfonic acid, but (a) a saturated or 2-16 carbon atoms (preferably 2-8) An acyl residue substitution product of an unsaturated fatty acid and an aromatic carboxylic acid, and a hydroxyl group substitution degree (DS) of about 0.001 to 1.8 (preferably about 0.005 to 1.5), Or (b) a monoacyl residue substitution product (single esterified product) of succinic acid, maleic acid or a derivative thereof having an alkyl / alkenyl modifying group having 1 to 26 carbon atoms (preferably 6 to 26 carbon atoms), and Those having a hydroxyl group substitution degree (DS) of about 0.001 to 0.5 (desirably about 0.005 to 0.3) can be suitably used.

  In the above, when the hydroxyl group substitution degree (DS) is too high, the tendency of the short chain substituent to be solubilized in cold water becomes strong, and it becomes difficult to recover the starch from the water slurry. In the crystallization operation, sufficient cooking (gelatinization) is not performed, which adversely affects the ability of the glue to form a film.

  More specifically, as saturated aliphatic carboxylic acid, acetic acid, propionic acid, butyric acid, lauric acid, myristic acid, palmitic acid, stearic acid and the like, as unsaturated aliphatic carboxylic acid, acrylic acid, methacrylic acid, Oleic acid, fumaric acid, maleic acid and the like can be suitably used, and benzoic acid and the like can be suitably used as the aromatic carboxylic acid.

  The etherified starch is a hydroxyalkylated product of ethylene oxide, propylene oxide, or mono-diglycidyl ether of mono- or di-valent alkyl alcohol having 1 to 8 carbon atoms (preferably 2 to 4 carbon atoms), and A compound having a molecular substitution degree (MS) of about 0.01 to 0.5 (desirably about 0.05 to 0.3) can be preferably used. If the degree of molecular substitution (MS) is too high, as in the case of the esterified starch, the tendency to solubilize in cold water becomes strong in the short-chain substituents, making it difficult to recover the starch from the water slurry. Thus, when the chain is long, sufficient cooking (gelatinization) is not performed in the gelatinization operation, which adversely affects the ability of the glue to form a film.

  The undercoat film is composed of the former or the latter (mass ratio) of the elastomer or the water-retaining / water-absorbing polymer and the gelatinizable starch = about 5/95 to 95/5 (preferably about 20/80 to 80/20). More desirably, a mixture of about 40/60 to 60/40) is used as the main component of the coating film.

  Here, as the elastomer, natural rubber (NR), synthetic rubber such as SBR and IIR, and various thermoplastic elastomers (olefin-based, styrene-based, polyamide-based, polyester-based) can be used.

  Further, the water retention / water absorption polymer is not particularly limited, and polyacetal or the like can be used, but polyacrylamide (PAAM) or polyvinyl alcohol (PVAL) can be preferably used.

  Here, the gelatinizable starches refer to those having a low viscosity and capable of being gelatinized instead of having a high degree of substitution, and include those paste liquids.

  Then, if necessary, at least the top coat film contains about 0.01 to 10 parts (preferably about 0.05 to 5 parts) of a hygroscopic mineral salt with respect to 100 parts of gelatinizable starch. In particular, in the case of relatively thick paper, such as paperboard, since operations such as folding are performed, if sufficient oil resistance cannot be expected by forming a film only on the paper surface, starch inside the paper layer This is effective because the penetration of the (glue solution) and the formation of the glue film inside the paper layer have a great influence.

  Here, as a hygroscopic mineral salt, sodium sulfate, potassium sulfate, sodium chloride, magnesium chloride, etc. can be used conveniently. Of course, it may be contained in the undercoat film.

  Further, if necessary, at least the top coat film contains about 5 to 50 parts (preferably about 10 to 30 parts) of an inorganic filler with respect to 100 parts of starch that can be gelatinized. In particular, when printing on coated paper (oil-resistant treated paper), the setability of the printing ink (offset, gravure, flexo ink, etc.) increases the amount of starch applied when only the surface of starch or modified starch is applied. It is possible to prevent being inferior with this, and it is effective.

  Here, the average particle diameter of the inorganic filler is desirably about 5 μm or less. If it exceeds about 5 μm, the smoothness of the coated surface is not preferred.

  Examples of the inorganic filler include water-insoluble inorganic compounds or metal oxides such as calcium carbonate, calcium sulfate, mica, talc, kaolin, and titanium oxide. Of these, calcium carbonate, kaolin, and talc are preferably used from the viewpoint of improving the setting property of ink and the like and cost. Of course, these can also be used 1 type or in mixture of 2 or more types.

  The oil-resistant paper that has been subjected to the above-mentioned oil-resistant treatment includes paper, bags, boxes, cups, and pet food bags used for food packaging, such as containers for foods containing oil, regardless of whether they are wet or dry. In addition, it can be used in various fields, such as paper used for non-food contact applications in which oil is used for commercialization.

  Next, a method for producing the oil-resistant treated paper having the above configuration will be described.

  In order to satisfy the above-mentioned requirements, a paste solution for the undercoat paint and the topcoat paint is prepared. At this time, when the elastomer is mixed in the undercoat coating film, the elastomer is supplied in the form of a fine particle dispersion. Here, when an elastomer is used in the undercoat paint, it is usually mixed with the paste liquid in the form of an emulsion (latex) in which the elastomer fine particles (dispersoid) are dispersed in a water-based or organic solvent dispersion medium or a suspension dispersion system. To do. Of these, rubber latex such as SBR latex can be suitably used. This is because rubber latex is excellent in flexibility, water resistance and elongation.

  For the application of the undercoat (undercoat) and topcoat (topcoat), no special equipment is required, and a two-roll size press, a gate roll size press, Surface treatment devices such as blade coaters and air knife coaters can be used.

  Examples and comparative examples relating to the present invention are described below, but it is clear that the present invention is not limited to these examples.

  Each modified starch used is as follows.

Oxidized starch: “SK-20” manufactured by Nippon Corn Starch; Ingredient: Corn starch Acetic acid starch: “AC30” manufactured by Nippon Corn Starch; Raw material: Tapioca starch, DS: 0.03
Single-esterified starch: prepared from corn starch (amylose content 35%) having a low viscosity with sulfuric acid in an aqueous slurry, and then adding 3 parts of octenyl succinic anhydride to starch.

Fluorine-based oil resistant agent "Asahi Guard" manufactured by Asahi Glass Co., Ltd.
SBR latex: “L1662” manufactured by Asahi Kasei Corporation PVAL: “N-300” manufactured by Nippon Synthetic Chemical Co., Ltd.
PAAM: “Hama Coat P-3800” manufactured by Misawa Ceramics Co., Ltd. Note that each of the undercoat and topcoat paints (glue solution) used a 15% paste solution of each starch. Various starch paste liquids were prepared by transferring starch slurry having a concentration of 10 to 15% to a glass container and then heating with stirring in a steam bath.

Each Example and Comparative Examples were prepared according to the formulations shown in Table 1 of the undercoat-overcoat paint Paper (50 g / m ²⁾ or paperboard (200g / m ^2), set the coating amount (undercoat: 2~3g / m ^2, Topcoat: 4-5 g / m ² g) 6 (TAPPI), air dried at 60 ° C., and cured at 105 ° C. for 1 minute to prepare a sample oil-resistant paper. In addition, the application amount of the undercoat / topcoat film was as shown in Tables 2 and 3. The coating amount was measured by measuring the weight of the paper before and after applying the paste and converting it per 1 m ² .

  The oil resistance of each item shown in Tables 2 and 3 was measured for each oil-resistant treated paper immediately after drying (curing) and after conditioning for 24 hours (23 ° C., 65% RH) in each of the examples and comparative examples.

  In Tables 2 and 3, “10-second bump” is measured with a Gurley-cob size tester, and “fold” is when paper coated with an oil-resistant agent is folded with the coated surface inside. The oil resistance of the crease part.

  “High-temperature humidification” is the degree of oil resistance measured after leaving the paper coated with an oil-resistant agent to stand at 80 ° C./95% RH for 24 hours, and “High-temperature retention” means applying the oil-resistant agent. It is the oil resistance measured after putting the obtained paper into a dryer at 80 ° C. for 30 minutes to make it dry.

  The oil resistance is measured in accordance with the kit oil resistance TAPPI / RC-338 (3M kit (JIS)) method, and the wet oil resistance is measured using a garle cob size tester with a contact time of 10 with water. After the passage of seconds, the sample was placed on a dry blotting paper, and after removing water that had not been absorbed, the oil resistance of the kit was measured immediately (the water absorption Cobb method (JIS) was adopted).

  The test results are as shown, and the oil-resistant treated paper of Example 1-8 according to the present invention is clearly superior to the prior art of Comparative Example 1-2. The effect comparable to the oil resistance of the paper which apply | coated the oil-proof agent conventionally used for general purpose is shown.

  For reference, the standard for oil resistance of paperboard is grade 6 or higher for kit oil resistance, and grade 9 or higher for detergents and packaging.

  Furthermore, the present inventors have confirmed that an effect is obtained even with oxidized starch and acid-treated starch, although inferior to etherified starch.

It is a model sectional view of the oil-resistant treated paper of the present invention.

Explanation of symbols

12 Oil-resistant treated paper 14 Oil-resistant treated layer 16 Undercoat film 18 Topcoat film

Claims (13)

An oil-resistant layer is provided on one or both sides of the paper substrate,
Each of the oil-resistant treatment layers includes an undercoat film (undercoat) and a topcoat film (topcoat) by applying a paste liquid,
The top coating film is composed mainly of a decomposed starch selected from oxidized starch or acid-treated starch or a hydroxylated hydrogen-substituted product of the decomposed starch that can be gelatinized,
The undercoat coating film, oil, wherein the mixture of the former / the latter (solid weight ratio) = 5/95 to 95/5 with elastomers aqueous colloid and gelatinized possible starch is coating the main component Treated paper. 2. The oil-resistant paper according to claim 1, wherein the elastomer aqueous colloid is rubber latex. The oil-resistant paper according to claim 2, wherein the rubber latex is SBR latex. The oil-resistant treated paper according to claim 1, 2 or 3, wherein the hydroxyl-hydrogen-substituted product is an esterified starch (acyl residue-substituted product) or an etherified starch. The esterified starch is an acyl residue substitution product of a saturated or unsaturated fatty acid having 2 to 16 carbon atoms or an aromatic carboxylic acid, and the hydroxyl group substitution degree (DS) is 0.001 to 1.8. The oil-resistant treated paper according to claim 4. The esterified starch is a monoacyl residue substitution product (single ester group introduction product) of a succinic acid, maleic acid or a derivative having an alkyl / alkenyl modified group having 1 to 26 carbon atoms, and a hydroxyl substitution degree ( 5. The oil-resistant paper according to claim 4, wherein DS) is 0.001 to 0.5. The etherified starch is a hydroxyalkylated product of ethylene oxide, propylene oxide, or mono-diglycidyl ether of mono- or di-valent alkyl alcohol having 1 to 8 carbon atoms in total, and the degree of molecular substitution (MS) is 0 oil treated paper of claim 4, wherein it is a .01 to 0.5. The hygroscopic mineral salt selected from the group of sodium sulfate, potassium sulfate, sodium chloride and magnesium chloride is further contained as a permeability improver in at least the top coat film. The oil-resistant paper according to any one of 7 above. At least the top coat film further contains a hygroscopic mineral salt selected from the group consisting of sodium sulfate, potassium sulfate, sodium chloride and magnesium chloride in an amount of 0.01 to 10 masses per 100 mass parts of the gelatinizable starch. oil treated paper according to any one of claims 1 to 7, characterized in that it is contained parts. The inorganic filler selected from the group consisting of calcium carbonate, calcium sulfate, mica, talc, kaolin and titanium oxide is further contained as a printing set property improving agent in at least the top coat film. 8. The oil-resistant treated paper according to 8 . At least 5 to 50 parts by mass of an inorganic filler selected from the group consisting of calcium carbonate, calcium sulfate, mica, talc, kaolin and titanium oxide is added to at least the top coat film. The oil-resistant treated paper according to claim 9, further comprising: The paper substrate has a basis weight of 400 g / m ² or less, and a coating film forming component amount in the undercoat film and the topcoat film is 0.1 to 20 g / m ^2. Oil-resistant paper in any one of -11. A method for producing an oil-resistant paper according to claim 12,
The former / the latter (weight ratio) of the elastomers aqueous colloid and gelatinized possible starch = 5/95 to 95/5 to the primer coating that auxiliary materials necessary to glue solution was added the mixture to the substrate paper After applying and forming the undercoat film,
A top coat film is formed on the undercoat film by applying a top coat paint with auxiliary materials added to the paste solution of the gelatinizable starch as required,
Furthermore, the oil-resistant paper manufacturing method characterized by making it dry.

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