JP2003027391A - Masking paper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide masking paper which has an excellent sizabling property and an excellent paper strength, excellent processing suitability, and good profitability. SOLUTION: This masking paper is characterized by adding carboxymethylcellulose having a substitution degree of 0.3 to 0.6 in an amount of 0.01 to 3.0 wt.% based on the weight of the absolutely dry pulp. The method for producing the masking paper is characterized by adding carboxymethylcellulose having a substitution degree of 0.3 to 0.6 and further adding at least one paper-strengthening agent in a total amount of 0.1 to 2.0 wt.% based on the weight of the absolutely dry pulp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking paper used for surface protection of a resin plate such as an acrylic plate or a vinyl chloride plate, and a method for producing the same. More specifically, the present invention relates to a masking paper which has high sizeability and is excellent in all of tensile strength and surface strength when dry and wet, and a method for producing the same.

[0002]

2. Description of the Related Art Masking paper is widely used as a paper which is attached to the surface of a resin plate such as an acrylic plate or a vinyl chloride plate to protect the surface of the resin plate. Masking paper is a processing step after papermaking, where wet paper is contacted with a Yankee dryer and glue is applied to the dried surface (glossy surface) of the wet paper.
It is attached to a resin plate such as an acrylic plate and used as a surface protective paper.

In the process of applying the above-mentioned glue, the see-through of the glue is a problem that the glue seeps out to the back surface of the masking paper. In order to prevent the strike-through of the glue, high size and high size are achieved. It is required to impart barrier properties. Furthermore, since the masking paper is in a wet state when the glue is applied, high wet strength is also required so as not to cause breakage.

In practical use as a resin plate protective paper, that is, when the resin plate is slid at the time of storage or transportation, the surface of the masking paper may be peeled off due to friction, resulting in high surface strength. Is desired.

Various techniques have been proposed in order to meet the above requirements. 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. Is
There are various problems such as low paper strength enhancing effect, high price, poor yield depending on paper making conditions, and insufficient strength developing effect in practical use.

Carboxymethyl cellulose (hereinafter CMC
It has long been known that cellulose derivatives such as carboxy) and carboxyethyl cellulose have the effect of increasing the strength of paper, but as a paper strength enhancer of the type used by adding them to a stock containing pulp fibers, However, there is a problem in that the strength increasing effect is small, and it is the fact that it is hardly used at present as a paper-making paper strength-increasing agent to be added to paper stock.

Further, in papermaking, a rosin sizing agent and an emulsion sizing agent are used for the purpose of imparting properties such as water repellency, water resistance and sizing property in order to impart high sizing property and barrier property in addition to a paper strengthening agent. Paper sizing agents such as alkenyl succinate, alkyl ketene dimer and alkenyl succinic anhydride are added to the pulp fiber slurry. One of the major problems with these sizing agents is poor sizing agent yield. For this reason, the sizing agent is added at a higher rate to deal with the problem, so that the inside of the papermaking system is contaminated, leaving 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.

[0008]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks of the prior art and has excellent size and paper strength,
It is an object of the present invention to provide a masking paper which is excellent in processability and economically favorable.

[0009]

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.
Masking paper characterized by being added.

(2) The wet tensile strength in the MD direction measured according to JIS P 8135 is 0.4 to 3.0 kN / m.
The masking paper according to (1), which is

(3) The thickness is 65 μm or less, and JIS
Stoeckigt sizing degree measured according to P 8122 is 3
The masking paper according to (1) or (2), wherein the masking paper has a duration of at least 2 seconds.

(4) JAPAN TAPPI Paper Pulp Test Method No. 1 The masking paper according to any one of (1) to (3), which has a surface strength of 14 or more measured according to Method A.

(5) After adding carboxymethyl cellulose having a substitution degree of 0.3 to 0.6, the total addition rate is
A method for producing a masking paper, which comprises adding at least one kind of paper strengthening agent within a range of 0.1 to 2.0% by weight based on the weight of bone-dry pulp.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As the raw material cellulose pulp in the present invention, for example, domestically produced such as Japanese oak, linden, Itaya maple, hemili, wig, harunile, birch, etc., beach, oak, alder, mangrove, eucalyptus, acacia, etc. Hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP) made from hardwood, and softwood unbleached kraft pulp (NU) made from softwood such as red pine, cedar, pine pine and spool.
KP) and bleached softwood kraft pulp (NBKP) are used, and these pulps are blended at an arbitrary ratio depending on the variety. To obtain proper paper strength, NBKP or N
UKP is blended, but considering good formation, the blending amount of these does not exceed 70% by weight. 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.

By adjusting the Canadian standard freeness (CSF) of the above pulp to 250 to 500 mL, preferably 350 to 450 mL, the air permeability is increased, and it is effective in preventing the strike-through of the paste when the paste is applied.

The CMC used in the present invention is a cellulose derivative synthesized by reacting monochloroacetic acid or the like with wood pulp, linter pulp or the like as a raw material, 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 substitution degree (etherification degree) of the CMC used for the present invention is 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 the pulp fiber, and becomes a mixture with the pulp fiber, so that the paper-strengthening effect of the paper-strengthening agent is not 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 be produced with various degrees of polymerization depending on the properties of the pulp fiber used and the method for producing CMC as described above, but the viscosity of a 1% aqueous solution is 5 to 16, 000mPa ・ s (0.1N-Na
Cl solvent, 25 ° C, B type viscometer), average degree of polymerization of 100
.About.4,500, and the average molecular weight is in the range of 20,000 to 1,000,000. CMC used in the present invention is carboxylic acid sodium salt or potassium salt.
C is carboxymethylcellulose sodium or carboxymethylcellulose potassium, but conventionally, the description of sodium and potassium is omitted, and is simply expressed as CMC.

In the present invention, the sodium salt, potassium salt or ammonium salt of CMC is used. However, the sodium salt of CMC is preferable because it is inexpensive and easily available and the obtained effect is high. Further, the solution concentration when adding CMC to the pulp slurry is 0.01 to 0.01% because if the concentration is too high, the viscosity becomes high and it becomes difficult to use.
It is in the range of 5.0%, preferably 0.1 to 3.0%.

The amount of CMC added in the present invention may vary depending on the degree of substitution, the type of pulp fiber, the required performance, etc., but is 0.0 based on the dry weight of pulp fiber.
1 to 3.0% by weight, preferably 0.05 to 1.0% by weight
Is. If it is used in excess of 3.0% by weight, the texture of the paper may be lowered or 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 better to set to mS / cm. The electrical conductivity is proportional to the amount of electrolyte in the slurry. The electrical conductivity of the slurry is 0.
If it is less than 4 mS / cm, the electrolytic mass is insufficient.
The molecules of CMC have an electrostatic repulsion force between them and pulp fibers, and they are not sufficiently adsorbed on the pulp fiber surface. The higher the electrical conductivity of the slurry, the greater the amount of CMC adsorbed on the pulp and the greater the effect, but the electrical conductivity of the slurry is 3.
At 0 mS / cm, almost all of CMC is adsorbed on the pulp fiber surface, so that the electric conductivity of the pulp slurry is 3.0 mS.
There is no need to make it above / cm.

When the CMC is added to the pulp fiber slurry, the CMC is adsorbed on the surface of the pulp fiber 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. However, 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, there is no unevenness in strength due to the paper strength enhancing agent, and high paper strength can be obtained.

The paper-strengthening agent used in the present invention is a so-called paper-making paper-strengthening agent or wet paper-strengthening agent, and 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.

Above all, the highest effect can be obtained when the paper-making paper strength enhancer containing polyacrylamide as the main component and the wet paper-strength strengthening agent containing urea resin as the main component are used in combination, but other types of Even if a paper strength enhancer or a wet paper strength enhancer is used, an excellent effect is exhibited.
The type of wet strength agent is not particularly limited, and several kinds of strength agents and wet strength agents can 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 0.3 to 1.5% by dry weight of pulp fiber. is there. If it is less than 0.1%, the effect of increasing the paper strength is insufficient and it is not suitable. On the contrary, if the paper strength enhancer is used at an addition rate of more than 2.0%, problems such as deterioration of the texture of the paper and deterioration of drainage may occur, which is not preferable.

In the present invention, in addition to the above paper-making paper strength enhancer, paper-making size and fixing agent, filler, pigment, retention aid, dye, defoaming agent, preservative, viscosity reducing agent and the like are known. The above papermaking chemicals can be added together, if necessary, and there is no particular limitation on the kind and addition ratio thereof. 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. 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 it is possible to prevent avatars that occur at the non-contact portion of the Yankee dryer and the sheet. Not suitable because it runs out.

On the other hand, when the temperature of the hot air exceeds 400 ° C. and becomes high, it is over-dried and the strength of the pulp is lowered, and thus 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 the 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 does not stick to the Yankee dryer and is not suitable. On the other hand, if the water content exceeds 65% and is large, a large amount of water vapor is generated between the Yankee dryer and the sheet, and the sheet floats, which is not suitable.

Even if the sheet has a proper amount of water that sticks to the Yankee dryer, the water vapor existing between the sheet and the Yankee dryer evaporates unevenly during the drying process, resulting in avatars (minus gloss loss). Therefore, in order to obtain gloss, it is necessary to uniformly and quickly remove the water content of the sheet attached to the Yankee dryer. For that purpose, it is indispensable to perform the step of sucking hot air containing steam at least once.

JIS P of the obtained masking paper
The wet tensile strength in the MD direction measured according to 8135 is preferably 0.4 to 3.0 kN / m. If the wet tensile strength is less than 0.4 kN / m, the wet tensile strength is insufficient in the processing step after paper making, and the operation during processing is hindered, which is not suitable. 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 resulting masking paper has a thickness of 65
The Steckigt sizing degree measured in accordance with JIS P 8122 at 3 μm or less is preferably 3 seconds or more. Masking paper is used to protect the surface of resin plates such as acrylic or vinyl chloride plates, and it is desired to be thin and lightweight for storage, transportation, and disposal after use of acrylic plates. The following are preferred. If the thickness is thin, the thinner it is, the better the Steckigt size is 3.
If it is less than 2 seconds, the glue will strike through during gluing in the processing step, and this will be unsuitable because it will interfere with the operating vegetables. Currently 45 μm
If it is less than the above range, the cushioning property is low, which may hinder the protection of the resin plate.

JAPAN of the obtained masking paper
TAPPI Paper Pulp Test Method No. The surface strength measured according to Method 1A is preferably 14 or more. If the surface strength is less than 14, the surface will peel off during practical use, which is not suitable for practical use.

The obtained masking paper JAPAN
TAPPI NO. The air permeability measured according to 5 is 30
Seconds to 60 seconds are preferred. When the paste is applied in a later processing step, the size and texture are required so that the paste does not strike through to the back surface. The air permeability is preferably 30 seconds to 60 seconds because deterioration of the formation causes this strike-through with a decrease in strength. If the time is less than 30 seconds, not only will the formation of a paste fail to induce strike-through of the paste at the time of applying the paste, but also the paper strength will decrease due to the poor formation, which is not preferable. On the contrary, if it exceeds 60 seconds, poor drying during sheet drying is induced, which is not preferable.

The basis weight of the obtained masking paper can be appropriately selected according to the required quality, but the density is 0.5 to 0.
It is important to be in the range of 9 g / cm ³ . When the density is 0.5 g / cm ³ or less, the cushioning property is obtained, but the paper strength is reduced, which is not suitable. Conversely, the density is 0.9
If it exceeds g / cm ³ , the cushioning property is poor and it is not suitable as a cushioning material in practical use because it hinders the protection of the resin plate.

[0038]

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.

Each physical property was measured according to the following methods. Test method (1) Thickness Measured according to JIS P-8118. (2) Breaking length (MD direction) Measured according to JIS P-8113. (3) Wet tensile strength (MD direction) It was measured according to JIS P 8135. (4) Steckigt sizing degree Measured according to JIS P 8122. (5) Surface Strength JAPAN TAPPI Paper Pulp Test Method No. 1
It measured according to the A method. (Unit A) (6) Oken type air permeability The Oken type air permeability is based on the JAPAN TAPPI Paper Pulp Test Method No. It measured according to 5.

Example 1 A mixture of 55% LBKP and 45% NBKP was added to prepare CSF3.
After beating to 90 mL, 0.1% of CMC having a substitution degree of 0.45 (solution viscosity of 1% solid content 900 mPa · s, Daiichi Kogyo Seiyaku Co., Ltd., 450A) was added to the absolute dry pulp weight. Thereafter, 2.0% of a sulfuric acid band was added as a fixing agent, 1.5% of a sizing agent (AL-120 manufactured by Japan PMC Co., Ltd.) was added, and a paper strength enhancer containing anionic polyacrylamide as a component (Arakawa Chemical Co., Ltd. PS manufactured by Kogyo Co., Ltd.
194-7) and 0.9% of a wet paper strengthening agent (Euramine P1510 manufactured by Mitsui Chemicals, Inc.) containing a cation-modified urea resin as a component, and a Yankee dryer was used using a Harper type paper machine. The temperature of hot air at 80 ℃
Then, hot air that was moist after being sprayed from the anti-dryer surface was sucked to obtain a masking paper.

Example 2 0.5% of a paper strength enhancer (PS194-7 manufactured by Arakawa Chemical Industry Co., Ltd.) containing anionic polyacrylamide as a component was used.
%, And a wet paper strengthening agent (Euramine P1510 manufactured by Mitsui Chemicals, Inc.) containing a cation-modified urea resin as a component was set to 0.5%, and paper was made in the same manner as in Example 1 to obtain a masking paper.

Example 3 Except that the addition ratio of CMC was 2.9% and the wet paper strength enhancer (Euramine P1510 manufactured by Mitsui Chemicals, Inc.) containing a cation-modified urea resin as a component was 1.0%. Paper was made in the same manner as in Example 1 to obtain a masking paper.

Example 4 A masking paper was obtained by making paper in the same manner as in Example 1 except that the CMC addition rate was 0.03%.

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) and masking paper. Got

Example 6 The same as Example 1 except that the substitution degree of CMC was 0.55 (solution viscosity of solid content 1%, 1600 mPa · s, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., serogen 4H). Papermaking was performed to obtain a masking paper.

Example 7 CMC having a degree of substitution of 0.40 (solution viscosity of 1% of solid content: 100 mPa · s, Daiichi Kogyo Seiyaku Trial # 41)
2C), and paper making was carried out in the same manner as in Example 1 except that the addition ratio of CMC was 1.0% to obtain a masking paper.

Comparative Example 1 A masking paper was obtained by making paper in the same manner as in Example 1 except that CMC was not added.

Comparative Example 2 Papermaking was carried out in the same manner as in Example 1 except that the degree of substitution of carboxymethyl cellulose was 0.7 (solution viscosity of solid content 1%, 1700 mPa · s, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Serogen BSH). Then I got a masking paper.

Comparative Example 3 A masking paper was obtained by making paper in the same manner as in Example 1 except that the addition rate of carboxymethyl cellulose was 0.03%.

Comparative Example 4 A masking paper was obtained by making paper in the same manner as in Example 1 except that the addition rate of carboxymethyl cellulose was 3.2%.

The physical properties of the obtained masking paper were measured, and the results obtained in Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.

[0052]

[Table 1]

As is clear from the results shown in Table 1, Example 1
The masking papers Nos. 3 to 3 have high sizeability and sufficient strength required for processing or for being put on a resin surface for practical use. On the other hand, when carboxymethyl cellulose is not added (Comparative Example 1), the substitution degree of carboxymethyl cellulose is out of the specified range (Comparative Example 2), or when the addition rate of carboxymethyl cellulose is out of the specified range and becomes small ( In Comparative Example 3), the breaking length becomes insufficient, and at the same time, the size property and the wet tensile strength are not sufficient values. Further, when the addition rate of carboxymethyl cellulose exceeds the prescribed range and becomes large (Comparative Example 4), not only the paper strength is lowered due to deterioration of the formation but also the size property is reduced.

[0054]

[Effects of the Invention] By adding a specific carboxymethyl cellulose, even if the addition amount of the paper strengthening agent is reduced,
It has become possible to obtain a masking paper used for surface protection of a resin plate such as an acrylic plate or a vinyl chloride plate having good strength and size during processing and practical use.

   ─────────────────────────────────────────────────── ─── 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 AG46 AG72                       AG77 AG78 AH16 AH17 BD10                       CF03 EA29 EA32 FA13 FA17                       GA42 GA50

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 masking paper which is characterized by being added in a weight percentage. 2. M measured according to JIS P 8135
The masking paper according to claim 1, wherein the wet tensile strength in the D direction is 0.4 to 3.0 kN / m. 3. A thickness of 65 μm or less and JIS P 8
3. The masking paper according to claim 1, wherein the Steckigt sizing degree measured according to 122 is 3 seconds or more. 4. JAPAN TAPPI Paper Pulp Test Method No. The masking paper according to any one of claims 1 to 3, wherein the surface strength measured according to the 1A method is 14 or more. 5. After adding carboxymethylcellulose having a degree of substitution of 0.3 to 0.6, the total addition rate is at least 0.1 to 2.0% by weight based on the weight of the absolutely dry pulp, and at least A method for producing a masking paper, which comprises adding one or more paper strengthening agents.