JP2003027399A - Wrapping paper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide wrapping paper which has an excellent sized property and excellent paper strengths when wetted and when dried, respectively, and has good profitability. SOLUTION: This wrapping paper is characterized in that carboxymethylcellulose having a substitution degree of 0.3 to 0.6 is added in an amount of 0.01 to 3.0% based on the weight of absolutely dried paper. The method for producing the wrapping paper is characterized by adding the carboxymethylcellulose having a substitution degree of 0.3 to 0.6 and then further adding at least one paper-strengthening agent for making the paper in a total amount of 0.1 to 2.0 wt.% based on the weight of the absolutely dried pulp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrapping paper used for packaging articles and a method for producing the same. More specifically, the present invention relates to a wrapping paper having a high size property and excellent in all tensile strengths when dry and wet, and a method for producing the same.

[0002]

2. Description of the Related Art Wrapping paper is widely used after being subjected to flexographic printing or the like, if necessary, for wrapping various articles and, if necessary, processed into bags and the like. As a packaged article, not only a dry article is packaged but also a package containing a large amount of water, such as fresh flowers and foods, has been packaged.

Various films are also used for packaging articles containing a large amount of water, but the use of films that generate harmful gas when burned has been disliked due to the heightened awareness of environmental problems in recent years. The demand for quality of wrapping paper is increasing.

As a quality requirement for the wrapping paper, a dry strength is required because a problem such as breakage of the wrapping paper during practical use occurs and the contents are spilled when the wrapping paper does not have a certain strength when packaging an ordinary article. .

On the other hand, when packaging an article containing a large amount of water as described above, there is a problem in that the content of the paper spills due to the paper being moistened, weakened and broken during packaging. High size and wet strength are required.

Various techniques have been proposed in order to meet the above-mentioned qualities. Conventionally, modified starch, polyacrylamide, polyamide, polyamide-epichlorohydrin resin, melamine-formaldehyde resin, urea-formaldehyde resin, etc. have been added to pulp fibers as a papermaking paper strength enhancer for the purpose of increasing the strength of paper. Has various drawbacks such as low strength of paper strength, high cost, poor yield depending on papermaking conditions and not giving sufficient strength-producing effect to paper in practical use. Is not satisfied with.

Carboxymethyl cellulose (hereinafter CMC
It has been known for a long time that cellulose derivatives such as carboxy) and carboxyethyl cellulose also have the effect of increasing the strength of paper, but as a paper strength enhancer of the type used by being added to a stock containing pulp fiber, There are problems such as a small strength-enhancing effect to be obtained, and it is the fact that it is rarely used at present as a paper-making paper-strengthening agent to be added to paper stock.

Further, in papermaking, in addition to a paper strengthening agent, a rosin sizing agent, an emulsion sizing agent, an alkenyl succinate, an alkyl ketene dimer, and an alkenyl for the purpose of imparting properties such as water repellency, water resistance and size. A paper sizing agent such as succinic anhydride is added to the pulp fiber slurry. One of the major problems with these sizing agents is poor sizing agent yield. For this reason, to increase the proportion of sizing agent to deal with it, the inside of the papermaking system is soiled,
Leave a problem in operability. Further, various cationic chemicals such as cation-modified starch, polyamide-epichlorohydrin resin, polyethyleneimine resin, polyacrylamide resin, polyamide resin, etc. are added for the purpose of improving the yield of the sizing agent. There are problems that the effect is not sufficient, that the chemical is expensive, that the effect is reduced by other chemicals added, and that the quality is not stable.

[0009]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art and provides a wrapping paper having excellent sizing property, wet and dry paper strength, and good economical efficiency. That is the purpose.

[0010]

The present invention covers the following respective inventions. (1) Carboxymethyl cellulose having a degree of substitution of 0.3 to 0.6 is 0.01 to 3.0% by weight based on the weight of the absolutely dry pulp.
Wrapping paper characterized by being added.

(2) The wrapping paper according to (1), which has a breaking length measured according to JIS P 8113 of 4.0 to 10.0 km.

(3) The wrapping paper according to (1) or (2), which has a wet tensile strength of 0.3 to 3.0 kN / m measured according to JIS P 8135.

(4) When the basis weight is X and the Steckigt size degree measured according to JIS P 8122 is Y,
The value of the Steckigt size degree Y is 0.165e ^0.06X ≤
The wrapping paper according to (1) to (3), characterized in that Y ≦ 0.75e ^0.05X .

(5) After the addition of carboxymethylcellulose having a degree of substitution of 0.3 to 0.6, at least one or more papermaking paper strength enhancer is added in a total amount of 0 to the absolute dry pulp weight. 1 to 2.0% by weight of the wrapping paper is added.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As the raw material cellulose pulp in the present invention, there are domestic hardwoods such as oak, linden, sycamore, hollyhock, wig, hornet, white birch, etc. Hardwood unbleached kraft pulp (LUKP) and hardwood bleached kraft pulp (LB)
KP), unbleached kraft pulp (NUKP) and conifer bleached kraft pulp (NBKP), which are made from softwood such as Akamatsu, Japanese cedar, Yonematsu, and spool, are used, and these pulps have an arbitrary ratio depending on the variety. Is compounded in. NBKP or NUKP is blended to obtain proper paper strength, but the blending amount is 55% by weight considering good formation.
It is preferable not to exceed. At this time, pulp is produced by a known kraft cooking method and bleached by a known method.
Considering the environment, it is preferable to bleach with ECF or TCF which does not use molecular chlorine element.

Canadian Standard Freeness (C
SF) is 400 to 600 mL, preferably 450 to 55
By adjusting to 0 mL, the formation is improved and the strength is not reduced, which is preferable.

The CMC used in the present invention is a cellulose derivative synthesized by reacting monochloroacetic acid and the like with wood pulp, linter pulp and the like as raw materials, and industrially known methods such as a water medium method and a solvent method. What is obtained by the manufacturing method is used as it is. Carboxyethyl cellulose, which is a cellulose derivative similar to CMC, has the same effect as that of the present invention, but is not preferable because it is less effective than CMC and is expensive.

The CMC used for the present invention preferably has a substitution degree (etherification degree) in the range of 0.3 to 0.6. If the degree of substitution is less than 0.3, it is insoluble in water, is not adsorbed on the surface of pulp fibers, and becomes a mixture with pulp fibers, so that the paper strength-enhancing effect of paper strength agents cannot be improved. On the other hand, when the degree of substitution exceeds 0.6, since many ionic groups are present in the molecule, electrostatic repulsion with pulp fibers having a negative charge is strong, and affinity with pulp fibers is high. Since it becomes scarce, even if the electrolyte coexists and the electrostatic repulsion is shielded to some extent, the adsorption on the pulp surface becomes insufficient. Therefore, the paper-strengthening agent added thereafter does not remain uniformly on the pulp surface, and a sufficient paper-strengthening effect cannot be obtained.

The CMC used in the present invention can have various degrees of polymerization depending on the properties of the pulp fiber used and the method for producing CMC as described above.
The viscosity of the aqueous solution is 5 to 16,000 mPa · s (0.1 N
-NaCl solvent, 25 ° C, B-type viscometer), average degree of polymerization of 100 to 4,500, and average molecular weight of 20,000 to 1,000,000. The CMC used in the present invention is carboxylic acid sodium salt or potassium salt, to be precise, CMC is carboxymethyl cellulose sodium or carboxymethyl cellulose potassium, but conventionally, the description of sodium or potassium is omitted, and CMC is simply used.
Display as.

In the present invention, the sodium salt, potassium salt or ammonium salt of CMC is used. However, the sodium salt of CMC is preferably used because it is inexpensive, easily available and highly effective. or,
When the CMC is added to the pulp slurry, the solution concentration becomes too viscous and the usage becomes difficult if the concentration is too high.
It is in the range of 0.01 to 5.0% by weight, preferably 0.1 to 3.0% by weight.

The amount of CMC used in the present invention may vary depending on the degree of substitution, the type of pulp fiber, the type of paper, the application, the required performance, etc. 01-3.0% by weight, preferably 0.0
It is 5 to 1.0% by weight. If it is used in excess of 3.0% by weight, the texture of the paper may be lowered and the drainage may be lowered. Furthermore, it leads to cost increase and is not economically realistic.

In the present invention, CMC is added to the pulp fiber slurry.
Is added as an aqueous solution, but the electric conductivity of the pulp fiber slurry is 0.4 mS / cm or more, preferably 0.6 to 3.0.
It is mS / cm. The electrical conductivity is proportional to the amount of electrolyte in the slurry. The electric conductivity of the slurry is 0.4 mS /
If it is less than cm, the electrolytic mass is insufficient, and therefore electrostatic repulsion acts between the CMC molecules and the pulp fiber, resulting in CMC.
Molecules are not fully adsorbed on the pulp fiber surface. The higher the electric conductivity of the slurry, the more the amount of CMC adsorbed on the pulp increases, and the effect becomes larger, but since the electric conductivity of the slurry is 3.0 mS / cm, almost all CMC is adsorbed on the pulp fiber surface, The electric conductivity of pulp slurry is 3.0
There is no need to make it above mS / cm.

When the CMC is added to the pulp fiber slurry, the CMC is adsorbed on the pulp fiber surface and the zeta potential of the pulp fiber is greatly changed to the negative side. Generally, the zeta potential is the electrokinetic potential of fine particles, and when there are charged particles on the surface, it is established by the equilibrium between the ion layer, which is relatively strongly bound to the particle surface, electrostatic force, and random thermal motion. There is an electric double layer with the outer layer, and when the particles move, the inner layer of the ionic layer surrounding them also becomes integral, and shows the surface charge of the moving body moving in the medium. Generally, the zeta potential of pulp fibers is in the range of 0 to -25 mV. In the present invention, the addition of CMC to the pulp fiber slurry lowers the zeta potential of the pulp fiber.
The effect of papermaking chemicals is remarkably improved when the voltage is lowered by mV or more.

When CMC is not added, the paper strengthening agent is adsorbed only at the adsorption points existing on the pulp fiber surface, but by adding CMC, not only the adsorption points of the pulp fibers but also the CMC uniformly adsorbed on the pulp are adsorbed. Therefore, since the paper strengthening agent is uniformly adsorbed with a high probability, the strength unevenness due to the paper strength enhancing agent is eliminated, and high paper strength is obtained.

The paper-strengthening agent used in the present invention is a so-called paper-making paper-strengthening agent or a wet paper-strengthening agent. Examples thereof include oxidized starch, amphoteric starch, cationized starch, acetylated starch,
Starch such as phosphate esterified starch, cationized guar gum, guar gum such as carboxymethylated guar gum,
Polyamide / epichlorohydrin resin, polyethyleneimine resin, polyacrylamide resin, polyamide resin,
Melamine resin, polyamide polyurea resin, cation-modified urea resin and the like are mentioned, and one or more of them are added after the addition of CMC.

The highest effect can be obtained when the paper-making paper strength enhancer containing polyacrylamide as the main component and the wet paper-strengthening agent containing paper containing urea resin as the main component are used in combination. Even if a strengthening agent and a wet strength agent are used, excellent effects are exhibited, so the types of the paper strength agent and the wet strength agent used in combination are not particularly limited, and several types of strength agents are further added. A wet strength agent can also be used in combination.

The addition ratio of these paper strengthening agents can be changed according to the required quality, but is 0.1 to 2.0% by weight, preferably 0.5 to 1.5% by weight, based on the dry weight of pulp fiber. Is. If it is less than 0.1% by weight, the effect of increasing the paper strength is insufficient and it is not suitable. On the other hand, if the paper strength enhancer is used at an addition rate of more than 3.0% by weight, problems such as deterioration of paper texture and deterioration of drainage may occur, which is not preferable.

In the present invention, in addition to the paper-making paper strength agent described above, known sizing agents and fixing agents for papermaking, fillers, pigments, retention aids, dyes, defoamers, preservatives, viscosity-reducing agents and the like are known. Papermaking chemicals can be added in combination as needed,
There are no particular restrictions on the type and addition rate of these. It is confirmed that these papermaking chemicals are not affected by the electric conductivity of the pulp fiber slurry, and they are appropriately selected and used according to the purpose.

The paper machine of the present invention may be selected from known wet paper machines such as a Fourdrinier paper machine, a gap former paper machine, a cylinder paper machine, and a short-net paper machine. . The formed paper layer is conveyed by a felt and dried by a Yankee dryer. It is generally known that a sheet dried with a Yankee dryer has high glossiness and high smoothness. The Yankee dryer is provided with a supply air that does not condense the evaporated water and a Yankee dryer hood for exhausting the supply air together with the evaporated water. Has been done.

In the present invention, the temperature of the Yankee dryer hot air is set in the range of 60 to 400 ° C, preferably 60 to 300 ° C. If the temperature of the hot air is less than 60 ° C, it becomes difficult to uniformly and quickly evaporate the water vapor generated between the surface of the Yankee dryer and the sheet, and the avatar (fine luster loss) generated in the non-contact portion of the Yankee dryer and the sheet. ) Is not suitable because it cannot be prevented.

On the other hand, when the temperature of the hot air becomes higher than 400 ° C., it becomes over-dried and the strength of the pulp is lowered, and the sheet strength is lowered, and the surface smoothness is deteriorated, and wrinkles and wrinkles are generated during the production of the sheet. It is easy for paper to run out,
It is not suitable because it makes sheet manufacturing difficult.

In order to prevent dew condensation of steam generated in the Yankee dryer hood, improve thermal efficiency, and prevent avatars, hot air is blown and hot air containing steam is sucked at least once. Usually, an appropriate amount of water is required for the sheet to stick to the Yankee dryer, and the range is preferably 45 to 65%. 45 water
If it is less than%, it is not suitable because it will not stick to the Yankee dryer. Conversely, if the water content exceeds 65%, a large amount of water vapor will be generated between the Yankee dryer and the sheet, and the sheet will float, making it suitable. Absent.

Even if the sheet has an appropriate amount of water that sticks to the Yankee dryer, the water vapor existing between the sheet and the Yankee dryer is non-uniformly evaporated during the drying process, resulting in avatars. In order to take out the water, it is necessary to uniformly and quickly remove the water content of the sheet attached to the Yankee dryer. To this end, at least one step of sucking hot air containing steam is required.
It is essential to do it more than once.

The breaking length in the MD direction measured according to JIS P 8113 of the obtained wrapping paper is 4.0 to 10.0 k.
It is preferably m. If the breaking length is less than 4.0 km, the strength may be insufficient at the time of packaging, and the product may be broken and the contents may be spilled, which is not suitable. On the contrary, 10.0
Increasing the diameter to more than km requires progressing beating of pulp and increasing addition of a paper strengthening agent, which not only deteriorates the formation of paper but also induces stains in the paper machine system,
Not suitable because stable papermaking cannot be achieved.

The wet tensile strength of the obtained packaging paper in the MD direction measured according to JIS P 8135 is 0.3 to 3.
It is preferably 0 kN / m. Wet tensile strength is 0.
When it is less than 3 kN / m, the wet tensile strength is insufficient when packaging an article containing a large amount of water, and it is unsuitable because it may break during use and spill the contents.
On the other hand, if the value exceeds 3.0 kN / m, it is necessary to advance the beating of the pulp and to increase the addition of the wet paper strengthening agent, which not only deteriorates the texture of the paper but also increases the paper machine system. It is not suitable because pulp easily adheres and stable paper cannot be made.

The basis weight of the obtained wrapping paper is X, JIS P
If the Steckigt sizing degree measured according to 8122 is Y, the value of the Steckigt sizing degree Y is 0.165e.
The range of ^{0.0 6 X} ≤ Y ≤ 0.75e ^0.05X is preferable. When the Steckigt sizing degree is less than the range of the formula, the permeability of water is increased and the wet tensile strength is lowered, so that it is not suitable for packaging an article containing a large amount of water.

The basis weight and thickness of the obtained wrapping paper can be appropriately selected according to the required quality.

The wrapping paper obtained in the present invention is for wrapping articles, and can be processed and used in the form of a bag.

[0039]

The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited to these examples. In the following examples and comparative examples,% is% by weight, and the amount of the additive added to the pulp slurry is
It is shown in% by weight based on the absolute dry weight.

The characteristics were measured according to the following methods. Test method (1) Breaking length (MD direction) It was measured according to JIS P 8113. (2) Wet tensile strength (MD direction) It was measured according to JIS P 8135. (3) Steckitt size size It was measured according to JIS P 8122.

Example 1 LBKP 65% and NBKP 35% were blended to obtain CSF5.
After beating to 10 mL, 0.1% of CMC having a substitution degree of 0.45 (solution viscosity of 1% solid content, 100 mPa · s, Daiichi Kogyo Seiyaku Co., Ltd., 450A) was added to the weight of the absolutely dry pulp. Then, 1.5% of sulfuric acid band was added as a fixing agent, and a sizing agent (AL-120 manufactured by Japan PMC Co., Ltd.) was added to 1.
Paper strength enhancer containing 0% added and further containing anionic polyacrylamide as a component (PS194-produced by Arakawa Chemical Industry Co., Ltd.)
7) 0.9% and 0.9% wet paper strengthening agent (Sumitomo Chemical's Sumireze resin 8% AC) containing melamine resin as a component, and using a Harper type paper machine with a Yankee dryer. The temperature of the hot air is 80 ° C., and the hot air that has been moistened after being blown from the anti-dryer surface is sucked, and the basis weight is 42.6 g.
A wrapping paper of / m ² was obtained.

Example 2 0.2% of a paper strength enhancer (PS194-7 manufactured by Arakawa Chemical Industry Co., Ltd.) containing anionic polyacrylamide as a component.
Then, paper making was carried out in the same manner as in Example 1 except that the wet paper strengthening agent containing a melamine resin (Sumitomo Chemical Co., Ltd., 8% AC) was 0.5%, and the basis weight was 37.1 g.
A wrapping paper of / m ² was obtained.

Example 3 A CMC addition rate of 2.9%, a paper strength enhancer (PS 194-7 manufactured by Arakawa Chemical Industry Co., Ltd.) containing anionic polyacrylamide as a component, and 0.5% of melamine resin. Was prepared in the same manner as in Example 1 except that the amount of the wet paper strength enhancer (Sumitomo Chemical Co., Ltd., 8% AC, made by Sumitomo Chemical Co., Ltd.) was 1.0% and the basis weight was 47.9 g / m ² . Got the paper.

Example 4 Example 1 except that the addition rate of CMC was 0.03%.
Paper making was carried out in the same manner as above to obtain a wrapping paper having a basis weight of 52.1 g / m ² .

Example 5 Paper was prepared in the same manner as in Example 2 except that the CMC had a degree of substitution of 0.35 (solution viscosity of 1% solid content, 100 mPa · s, manufactured in-house). Amount 43.9 g / m
² wrapping paper was obtained.

Example 6 CMC having a substitution degree of 0.55 (solution viscosity of 1% solid content 1600 mPa · s, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., serogen 4H) and the addition rate of CMC was 1 Paper was made in the same manner as in Example 2 except that the content was changed to 0.0%, and the basis weight was 42.4 g /
A wrapping paper of m ² was obtained.

Example 7 CMC having a degree of substitution of 0.40 (solution viscosity of 1% solid content: 900 mPa · s, Daiichi Kogyo Seiyakuhin # 412)
Paper making was carried out in the same manner as in Example 1 except that it was C), and a wrapping paper having a basis weight of 37.5 g / m ² was obtained.

Comparative Example 1 Paper making was carried out in the same manner as in Example 1 except that CMC was not added to obtain a wrapping paper having a basis weight of 42.3 g / m ² .

Comparative Example 2 The substitution degree of CMC was 0.7 (solution viscosity 1 at a solid content concentration of 1% 1
700 mPas, Dai-ichi Kogyo Seiyaku Co., Ltd., Serogen BSH)
Paper was made in the same manner as in Example 2 except that the weight was 42.5 g.
/ M ² wrapping paper was obtained.

Comparative Example 3 CMC was added at 0.03%, a paper-strengthening agent (PS194-7, manufactured by Arakawa Chemical Industry Co., Ltd.) containing anionic polyacrylamide as a component, and melamine resin. Was prepared in the same manner as in Example 1 except that the amount of the wet paper strengthening agent (Sumitomo Chemical Co., Ltd., 8% AC, manufactured by Sumitomo Chemical Co., Ltd.) was 0.5%, and the basis weight was 42.1 g / m ² wrapping paper. Got

Comparative Example 4 Paper was made in the same manner as in Example 1 except that the CMC addition rate was 3.2% to obtain a wrapping paper having a basis weight of 37.5 g / m ² .

The physical properties of the obtained wrapping paper were measured, and the results of Example 1
Table 1 shows the results obtained in Examples 7 to 7 and Comparative Examples 1 to 4.

[0053]

[Table 1]

As is clear from the results shown in Table 1, Example 1
The wrapping papers Nos. 7 to 7 have a sufficient strength required for practical use as a wrapping paper or a bag for articles, and have high size and sufficient wet tensile strength to withstand the wrapping of articles containing a large amount of water. have. On the other hand, when CMC is not added (Comparative Example 1), the substitution degree of CMC is out of the specified range (Comparative Example 2), or when the CMC addition rate is out of the specified range and becomes small (Comparative Example 3). ), Size, and wet tensile strength are not sufficient values. In addition, when the CMC addition rate exceeds the prescribed range and becomes large (Comparative Example 4), the formation deteriorates and the paper strength decreases.

[0055]

EFFECTS OF THE INVENTION By adding CMC having a degree of substitution of 0.3 to 0.6 in a certain range and adding a paper strength enhancer in a specific range, good strength and sizing property in practical use can be obtained. It has become possible to obtain a wrapping paper used when packaging an article.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Kitao             Made by Oji 1-10-6 Shinonome, Koto-ku, Tokyo             Paper Co., Ltd. Shinonome Research Center F-term (reference) 4L055 AA02 AA03 AC06 AG08 AG46                       AG73 AG81 AH11 AH16 AH17                       EA07 EA10 EA32 FA13 FA17                       GA05

Claims (5)

[Claims] 1. Carboxymethyl cellulose having a degree of substitution of 0.3 to 0.6 is 0.01 to 3.0 based on the weight of the absolutely dry pulp.
A wrapping paper characterized by being added by weight%. 2. The wrapping paper according to claim 1, wherein the breaking length measured according to JIS P 8113 is 4.0 to 10.0 km. 3. The packaging paper according to claim 1, wherein the wet tensile strength measured according to JIS P 8135 is 0.3 to 3.0 kN / m. 4. When the basis weight is X and the Steckigt size degree measured according to JIS P 8122 is Y, the value of the Steckigt size degree Y is 0.165e ^{0.06 X} ≦ Y ≦
The wrapping paper according to any one of claims 1 to 3, which has a range of 0.75e ^0.05X . 5. After addition of carboxymethyl cellulose having a degree of substitution of 0.3 to 0.6, at least one or more papermaking paper strength enhancers are added in a total amount of 0. A method for producing a wrapping paper, which comprises adding 1 to 2.0% by weight.