JP2018096014A - Oil-resistant paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-resistant paper which exhibits a sufficient kit value even when it is bent and used. The present invention is an oil-resistant paper comprising a base paper and a coating film containing cellulose nanofibers as a main component and laminated on at least one surface of the base paper, wherein the coating film contains glycerin, sorbitol and the like. It is characterized by containing a wet paper strength enhancer. A coating containing cellulose nanofibers as the main component provides sufficient kit values, and since this coating contains glycerin, sorbitol and a wet paper strength enhancer, the coating is highly flexible and pinholes in the coating when bent. Is unlikely to occur, and a sufficient kit value can be maintained. It is preferable that the coating film further contains sodium alginate. [Selection diagram] None

Description

  The present invention relates to an oil resistant paper.

  Oil-resistant paper is widely used as a packaging material for foods containing oil. The oil-resistant paper can prevent the oil content from the packaged contents from oozing out and prevent the outer surface from being soiled by the oil content.

  In such an oil-resistant paper, the base paper and cellulose nanofiber as a main component are laminated on at least one surface of the base paper so that water vapor permeability and the like are good while exhibiting a sufficient kit value. An oil-resistant paper provided with a coating has been proposed (see JP 2011-74535 A).

JP 2011-74535 A

  As a result of the study by the present inventors, the oil-resistant paper described in the above publication has a hard coating film that is laminated on the base paper, so that pinholes are generated in the coating film when folded for packaging, etc. Turned out to be reduced.

  In view of the above conventional disadvantages, an object of the present invention is to provide an oil-resistant paper that exhibits a sufficient kit value even when it is folded and used.

  In order to solve the above-mentioned problems, the present invention is an oil-resistant paper comprising a base paper and a coating film containing cellulose nanofibers as a main component and laminated on at least one surface of the base paper, wherein the coating film is glycerin. And sorbitol and a wet paper strength enhancer.

  In the oil-resistant paper, a coating containing cellulose nanofibers as a main component has a sufficient kit value, and since this coating further contains glycerin, sorbitol and a wet paper strength enhancer, the coating is rich in flexibility and folded. In addition, pinholes are less likely to occur in the coating, and a sufficient kit value can be maintained.

  It is preferable that the coating further contains sodium alginate, whereby the flexibility of the coating is improved and the effect of maintaining the kit value against bending is improved.

  The oil resistant paper of the present invention can exhibit a sufficient kit value even when it is folded and used.

  Hereinafter, embodiments of the present invention will be described in detail.

[Oil-resistant paper]
The oil-resistant paper includes a base paper and a film laminated on one surface of the base paper. The coating contains cellulose nanofibers as a main component, and further contains glycerin, sorbitol, and a wet paper strength enhancer. For this reason, the oil-resistant paper can exhibit a sufficient kit value because the coating contains cellulose nanofibers as a main component, and further, since this coating contains glycerin, sorbitol and a wet paper strength enhancer, It is excellent in uniform coating and film forming properties, the coating is rich in flexibility, and pinholes are hardly generated in the coating when it is bent, and a sufficient kit value can be maintained.

<Base paper>
The base paper of the oil-resistant paper contains raw material pulp and filler, and may further contain a yield improver, a paper strength enhancer and the like as appropriate. In addition, the oil-resistant paper can appropriately contain a size material, a size fixing material, and the like. This base paper is obtained by papermaking a slurry containing raw pulp and filler.

  Examples of the raw material pulp include mechanical pulp, chemical pulp, semi-chemical pulp, and synthetic pulp. Some of these raw material pulps may be provided as waste paper pulp containing mechanical pulp, chemical pulp and the like. Preferably, the content of glycerin, sorbitol and wet paper strength enhancer in the base material is reduced by suppressing the filler content in the noble paper so that the ash content in the noble paper according to JISP8251 is 16% or less. Controls the penetration of cellulose nanofiber, enables uniform film formation of cellulose nanofibers, glycerin, sorbitol, and wet paper strength enhancer, and makes it possible to obtain a uniform film and film formation, which is unlikely to occur when the film is peeled off. Thus, a decrease in kit value can be suppressed, and a sufficient kit value can be maintained.

  As the mechanical pulp contained in the raw material pulp, one kind or plural kinds of groundwood pulp (GP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) and the like can be used.

  On the other hand, as the chemical pulp contained in the raw material pulp, one kind or plural kinds such as kraft pulp (KP), sulfide pulp (SP), alkali pulp (AP) can be used.

  The mechanical pulp and chemical pulp may be bleached (BP) bleached or unbleached (UP) unbleached, both bleached and unbleached pulp. May be included.

In addition, as the above-mentioned waste paper pulp, one or plural kinds of magazine waste paper deinked pulp, newspaper waste paper deinked pulp and the like recycled from magazine waste paper or leaflet waste paper can be used.
Preferably, the raw material pulp composition mainly composed of kraft pulp has a homogeneous cellulose nanofiber, glycerin, sorbitol, and wet paper strength enhancer, rather than using pulp that exhibits high water absorption and oil absorption, such as mechanical pulp and waste paper pulp. It is possible to form a film and improve the film formability.

The lower limit of the basis weight of base paper is preferably 40 g / ^{m 2,} more preferably 50 g / ^{m 2,} particularly preferably 60 g / ^{m 2.} If the basis weight of the base paper does not satisfy the above lower limit, the strength of the oil-resistant paper may be insufficient. In contrast, the upper limit of the basis weight of the base paper is not particularly limited, but is preferably 90 g / ^{m 2,} more preferably 80 g / ^{m 2,} particularly preferably 75 / cm ^2. When the basis weight of the base paper exceeds the above upper limit, the tension decreases and unevenness of impregnation of the cellulose nanofiber, glycerin, sorbitol, and wet paper strength enhancer into the paper layer is likely to occur, and it is homogeneous. The formation of the coating film becomes difficult, and the rigidity of the oil-resistant paper is increased, which makes it difficult to be deformed into a packaging shape and causes a problem that the kit value is lowered at the bent portion.

<Coating>
As described above, the coating contains cellulose nanofibers as the main component. The “main component” is a component having the largest content, for example, a component having a content of 50% by mass or more. Here, as a minimum of content of cellulose nanofiber in a coat, 70 mass% is preferred, 75 mass% is more preferred, and 80 mass% is still more preferred. On the other hand, as an upper limit of content of a cellulose nanofiber, 95 mass% is preferable, 90 mass% is more preferable, and 85 mass% is further more preferable. If the content of cellulose nanofibers does not satisfy the above lower limit, the desired kit value may not be achieved. When the content of the cellulose nanofibers exceeds the above upper limit, the viscosity becomes high and the film formation is inferior, and the film becomes hard, and there is a possibility that the kit value and the workability are lowered particularly at the bent portion.

  The “cellulose nanofiber” refers to a fine cellulose fiber obtained by defibrating pulp fibers, and generally refers to a cellulose fiber including cellulose fine fibers having a fiber width of nanosize (1 nm to 1000 nm). . Here, as the cellulose nanofibers, those refined by mechanical treatment, those refined not only by mechanical treatment but also by chemical treatment, and the like can be used.

  The cellulose nanofiber has one peak in a pseudo particle size distribution curve measured by a laser diffraction method in an aqueous dispersion state. The particle size (mode) that becomes a peak in the pseudo particle size distribution curve is preferably 5 μm or more and 25 μm or less. When cellulose nanofibers have such a particle size distribution, they can exhibit good performance that is sufficiently refined. The “pseudo particle size distribution curve” means a curve indicating a volume-based particle size distribution measured using a particle size distribution measuring apparatus (for example, a laser diffraction / scattering type particle size distribution measuring instrument manufactured by Seishin Corporation).

  As a minimum of content of the above-mentioned glycerin in a coat, 1 mass% is preferred and 3 mass% is more preferred. On the other hand, as an upper limit of content of glycerol, 15 mass% is preferable and 8 mass% is more preferable. If the content of glycerin does not satisfy the above lower limit, the flexibility of the film may be insufficient. On the other hand, when the content of glycerin exceeds the above upper limit, the content of cellulose nanofibers may be relatively decreased. Originally glycerin is widely used as a food additive, such as sweeteners, preservatives, moisturizers, thickening stabilizers, and the like, and is a chemical that is suitably used for food applications. The present inventors pay attention to a thickening stabilizer that is an effect of glycerin, and find that it is effective for stabilizing the thickening by containing cellulose nanofibers by making a desired content in the coating. ing.

  As a minimum of content of the above-mentioned sorbitol in a coat, 1 mass% is preferred and 3 mass% is more preferred. On the other hand, the upper limit of the content of sorbitol is preferably 15% by mass, and more preferably 8% by mass. If the content of sorbitol does not satisfy the above lower limit, the flexibility of the film may be insufficient. On the other hand, when the content of sorbitol exceeds the above upper limit, the content of cellulose nanofibers may be relatively reduced. Although sorbitol is a drug used as a sweetener for products, it is often used as a thickener to easily retain moisture. By containing a desired amount in the coating, the coating itself is combined with cellulose nanofibers when forming the coating. It is possible to maintain a high stability of the resin, and a uniform film can be formed while maintaining the homogeneity of the cellulose nanofibers, glycerin, sorbitol, and the wet paper strength enhancer.

  As a minimum of content of the above-mentioned wet paper strength enhancer in a coat, 0.1 mass% is preferred and 0.3 mass% is more preferred. On the other hand, the upper limit of the content of the wet paper strength enhancer is preferably 2% by mass, and more preferably 1% by mass. If the content of the wet paper strength enhancer does not satisfy the lower limit, the flexibility of the film may be insufficient. On the other hand, when the content of the wet paper strength enhancer exceeds the above upper limit, the content of the cellulose nanofiber may be relatively decreased. The wet paper strength agent is appropriately selected from one or more known materials such as polyamide epichlorohydrin, melamine resin, melamine formaldehyde resin, urea formaldehyde resin, polyamide, polyamide epoxy, polyvinylamine and the like. Can be used. The wet paper strength enhancer is a drug for suppressing a decrease in paper strength when the paper is wet, and polyamide epichlorohydrin is most frequently used for tissue paper, paper towels and the like. Cationic polyamide epichlorohydrin, in particular, has a tendency to depend on the amount of carboxy groups that are anionic groups in the pulp, has a large amount of fixing with cellulose nanofibers, and is a problem in the present invention. Even when used, it is possible to provide an oil-resistant paper that exhibits a sufficient kit value.

  The coating can further contain sodium alginate. Thereby, the softness | flexibility of a film can further be improved. As a minimum of content of sodium alginate in a film, 2 mass% is preferred and 4 mass% is more preferred. On the other hand, as an upper limit of content of sodium alginate, 15 mass% is preferable and 8 mass% is more preferable. If the content of sodium alginate does not satisfy the above lower limit, the effect of improving the flexibility of the film may be insufficient. On the other hand, when the content of sodium alginate exceeds the above upper limit, the content of cellulose nanofibers may be relatively decreased. In earnest study by the present inventors, it is also called one of plant fibers as well as cellulose nanofibers, and further contains thickening polysaccharides and gelling agents as food additives, sodium alginate used for various purposes such as pharmaceutical applications As a result, it has been found that the effect of producing smooth film moldability can be obtained while the film contains cellulose nanofibers.

  The coating can further contain polynormal vinyl acetamide. Thereby, the softness | flexibility of a film can further be improved. As a minimum of content of polynormal vinyl acetaldehyde in a coat, 0.1 mass% is preferred and 0.3 mass% is more preferred. On the other hand, the upper limit of the content of polynormal vinyl acetaldehyde is preferably 2% by mass, and more preferably 1% by mass. If the content of polynormal vinyl acetohydride does not satisfy the above lower limit, the effect of improving the flexibility of the film may be insufficient. On the other hand, if the content of polynormal vinyl acetohydride exceeds the above upper limit, the content of cellulose nanofibers may be relatively reduced.

  The coating film is formed by coating a coating liquid containing components such as cellulose nanofiber, glycerin, sorbitol, and wet paper strength enhancer on one surface of the base paper.

  The lower limit of the average thickness of the coating is preferably 3 μm, and more preferably 5 μm. On the other hand, the upper limit of the average thickness of the coating is preferably 20 μm and more preferably 15 μm. If the average thickness of the coating does not satisfy the above lower limit, the desired kit value may not be achieved. On the other hand, if the average thickness of the coating exceeds the above upper limit, the coating may become unnecessarily too thick.

The lower limit of the coating amount of the coating liquid in forming the coating film (solid content), preferably ^{1g / m 2, 3g / m} 2 is more preferable. On the other hand, the upper limit of the coating amount is preferably ^{15g / m 2, 10g / m} 2 is more preferable. If the coating amount does not satisfy the above lower limit, the coating becomes too thin, and the desired kit value may not be achieved. On the other hand, if the coating amount exceeds the above upper limit, the coating may become unnecessarily thick.

    EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example 1]
As the base paper, PPC paper (trade name “Standard Type II” manufactured by Cownet Co., Ltd.) having a basis weight of 64.4 g / m ² was used. Cellulose nanofibers, glycerin, sorbitol and a wet paper strength enhancer were dispersed in water to prepare a coating solution. This coating solution was applied to one surface of the base paper and dried to form a film having an average thickness of 10 μm, whereby an oil-resistant paper of Example 1 was obtained. The contents of cellulose nanofiber (CNF), glycerin, sorbitol and wet paper strength enhancer in the coating are as shown in Table 1 (in the table, the numerical values indicate the content (mass%) in the coating, and “−”). Means 0% by mass). The used cellulose nanofibers had a particle size (mode) that was a peak in a pseudo particle size distribution curve measured by a laser diffraction method in an aqueous dispersion state of 15 μm. In addition, the trade name “Purified Glycerin” (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) is used as glycerin, and the trade name “Sorbit KK (60%)” (manufactured by MC Food Specialties Co., Ltd.) is used as sorbitol. The product name “WS4024” (manufactured by Seiko PMC Co., Ltd.) was used.

[Example 2]
An oil-resistant paper of Example 2 was obtained in the same manner as in Example 1 except that sodium alginate was further contained in the coating, and the content of each component was as shown in Table 1. In addition, a brand name “Argy Deluxe” (manufactured by Kimika Co., Ltd.) was used as sodium alginate.

[Example 3]
An oil-resistant paper of Example 3 was obtained in the same manner as in Example 1 except that the coating further contained polynormal vinyl acetohydride (PNVA) and the content of each component was as shown in Table 1. In addition, a trade name “GE-192-053” (manufactured by Showa Denko KK) was used as the polynormal vinyl acetaldehyde.

[Example 4]
An oil resistant paper of Example 4 was obtained in the same manner as in Example 1 except that sodium alginate and polynormal vinyl acetohydride were further contained in the coating, and the contents of each component were as shown in Table 1. In addition, the same thing as Example 2 and 3 was used for sodium alginate and polynormal vinyl acetohydride.

[Comparative Example 1]
An oil-resistant paper of Comparative Example 1 was obtained in the same manner as in Example 1 except that the content of the coating was changed as shown in Table 1.

[Comparative Example 2]
The oil-resistant paper of Comparative Example 2 was obtained in the same manner as in Example 1 except that cellulose nanofibers and polyvinyl alcohol (PVA) were contained in the coating in the amounts shown in Table 1.

[Oil resistance test]
For the oil-resistant paper of Examples 1 to 4 and Comparative Examples 1 and 2, a fold-folded portion (a portion folded so that the coating is on the outside) and a valley fold portion (a portion folded so that the coating is on the inside) are made The kit values were measured at flat portions (portions without fold lines), mountain fold portions and valley fold portions. If the kit value was grade 10 or higher, it was judged as A (excellent), if the kit value was grade 9 or higher, it was judged as B (good), and if the kit value was below grade 9, it was judged as C (impossible). The results are shown in Table 1.

  As is clear from Table 1, the oil-resistant paper of Examples 1 to 4 in which glycerin, sorbitol, and a wet paper strength enhancer are contained in a coating containing cellulose nanofiber as a main component is not only a flat part but also a mountain fold And the oil resistance of the valley fold portion is good. On the other hand, the oil resistant papers of Comparative Examples 1 and 2 have good oil resistance at the flat portion, but pinholes were formed in the coating at the mountain folds, and sufficient oil resistance was not obtained. In addition, although the pinhole was formed in the film in the valley fold part of the oil resistant paper of Comparative Examples 1 and 2, a certain oil resistance was obtained.

  Moreover, when sodium alginate was further included in the coating as in Examples 2 and 4, the effect of maintaining oil resistance when folded was improved.

  Since the oil-resistant paper of the present invention can exhibit a sufficient kit value even when it is folded and used as described above, it is preferably used as a packaging material for various objects containing oil. it can.

Claims (2)

An oil-resistant paper comprising a base paper and a coating layer containing cellulose nanofibers as a main component and laminated on at least one surface of the base paper,
The oil-resistant paper, wherein the coating contains glycerin, sorbitol and a wet paper strength enhancer.   The oil-resistant paper according to claim 1, wherein the coating further contains sodium alginate.