JP3907650B2 - Craft wrapping paper - Google Patents

Description

  The present invention relates to craft wrapping paper.

  Kraft paper uses kraft pulp obtained by kraft cooking of wood, and has excellent strength such as tensile strength, so it is filled with agricultural products, chemicals, flour, cement, etc. Widely used as a multilayer bag. It is also used for envelopes by taking advantage of its strength.

  On the other hand, in recent years, from the viewpoint of protecting wood resources, blending of used paper parf is also progressing in kraft wrapping paper. However, waste paper pulp contains a lot of ash represented by calcium carbonate, etc., and rosin-based sizing agents that have been used in the past do not have a sufficient size effect in the high pH range, and are insufficient in size. This causes problems such as the generation of paper dust during printing and the sag of base paper due to moisture absorption. It is also possible to adjust to a low pH where the rosin sizing agent is effective by using an auxiliary chemical such as a sulfuric acid band, but in this case, the sulfuric acid band and ash aggregate to cause contamination in the system and New troubles such as smearing on the paper surface occur.

In view of such circumstances, the present invention uses an alkyl ketene dimer as a sizing agent, so that the sizing effect is sufficiently high even under conditions in which waste paper pulp is highly blended. An object of the present invention is to provide a craft wrapping paper that has been solved and is suitable for processing as a wrapping paper.
Another object of the present invention is to provide a kraft wrapping paper that satisfies the standards conforming to the three kinds of craft paper quality standards defined in JIS P 3401-2000. In the three types of JIS P 3401-2000 kraft paper, several basis weights and quality standards corresponding to each basis weight are defined, but diversification of basis weight standards due to multi-use of craft wrapping paper. Accordingly, the present invention is also applied to kraft wrapping paper having a basis weight other than these several basis weights.

The craft wrapping paper of the present invention is a craft wrapping paper that satisfies a standard conforming to three types of quality standards defined in JIS P 3401-2000, having a standard basis weight of 50 to 120 g / m ² , A finished raw material obtained by adding 0.5 to 5.0 kg / t of an alkyl ketene dimer as an internal sizing agent to a pulp raw material composed of 20 to 50% by weight of kraft pulp and waste paper pulp and mechanical pulp. A surface treatment agent consisting of oxidized starch and / or polyacrylamide is externally added by a roll transfer method in the middle of the drying process, and is flattened by a calender having one or more nips after the drying process, It is calculated from the measured Cobb sizing degree in JIS P 8140-1998 and (g / ^{m 2)} basis weight and (g / ^{m 2)} (co The value of Busaizu degree / basis weight) is characterized in that 0.1 to 0.25.

  (Cobb sizing / basis weight) is in the above numerical range. If this value is smaller than 0.1, the required quality of the craft wrapping paper, which is an application of the present invention, cannot be satisfied, and 0.25 This is because excessive quality will result, and manufacturing costs and operability will be extremely poor. In addition, this kraft wrapping paper contributes to wood resource protection because it contains waste paper pulp. By using the internally added sizing agent having the above specifications, high sizing properties can be maintained even in a system in which waste paper pulp is highly blended, and the problem of paper dust during printing and moisture absorption wrinkles during storage can be solved.

In addition, the standards according to the three craft paper quality standards defined in JIS P 3401-2000 (hereinafter also referred to as standards in accordance with JIS P 3401) are standard basis weights of 50 g / m ² , 60 g / m ² , ^{70g / m 2, 80g / m} 2, the case of ^{100g / m 2, 120g / m} 2 is, SS-50 defined in kraft paper three JIS P 3401-2000, SS-60, SS-70, SS -80, SS-100, SS-120 quality standards themselves. If the standard basis weight is other than these values, proportional calculation is performed from the basis weight and the standard basis weights of these six kinds of symbols. Means quality standards. For example, when the standard basis weight is 90 g / m ² , the basis weight is just an intermediate value between the standard basis weight of SS-80 (80 g / m ² ) and the basis weight of SS-100 (100 g / m ² ). Therefore, the “standard according to JIS P 3401” in this case is the following standard that is proportionally calculated from the standard value of SS-80 and the standard value of SS-100.
(Standard according to JIS P 3401 when the standard basis weight is 90 g / m ² )
Basis weight tolerance: ± 2.5 (g / m ² )
Tensile strength (longitudinal) ... 4.6 (kN / m) or more Tensile strength (lateral) ... 1.9 (kN / m) or more Tear strength (longitudinal) ... 805 (mN) or more Tear strength (horizontal) ... 875 (mN) or more Sizing degree ... 16.5 (seconds) or more Thickness ... 124 (μm) or more

  In this way, the standard according to JIS P 3401 is an extension of the standard to craft papers with a grammage other than the six grammages specified in the three craft papers of JIS P 3401-2000. It is. In other words, the kraft wrapping paper of the present invention is equivalent to the three craft paper standards even in the kraft wrapping paper having a basis weight other than the six basis weights defined in the three types of JIS P 3401-2000 kraft paper. It meets the quality standards.

  It is preferable to use kraft wrapping paper that has been flattened by a heating calendar in which the temperature of the surface of at least one metal roll is 80 to 150 ° C. By setting the temperature of the roll surface to 80 to 150 ° C., the surface can be smoothed while maintaining bulkiness, and the printability can be improved. Moreover, when the temperature is set to 80 ° C. to 150 ° C., the smoothness of the surface cannot be sufficiently increased when the temperature is lower than 80 ° C., and the printability is not improved. Because it becomes.

The externally added surface treating agent is oxidized starch, and the coating amount is preferably 0.8 to 3.5 g / m ² in solid amount. By using oxidized starch, printability can be further enhanced. Also, to that the 0.8~3.5g / ^{m 2} is because external addition the effect is reduced to a surface treatment agent is less than 0.8 g / ^{m 2,} when more than 3.5 g / ^{m 2} This is because resistance in the folding process of the bag making machine increases and bag making efficiency decreases.

  As described above, according to the present invention, the size effect is sufficiently high even under a high blended condition of used paper pulp, eliminating the problem of paper dust during printing and handling, and processing as packaging paper. Kraft wrapping paper with suitability can be provided.

Hereinafter, embodiments of the present invention will be described.
As described above, in JIS P 3401-2000, six types of craft paper (SS-50, SS-60, SS-70, SS-80) having a standard basis weight of 50 to 120 g / m ² as three types of craft paper. , SS-100, SS-120). The craft wrapping paper of the present invention has a basis weight of 50 to 120 g, such as a kraft paper having a basis weight of 85 g / m ² , in addition to those satisfying any of these six types of standards, Includes wrapping paper.

  As pulp blending, 20 to 50% by weight of kraft pulp is used with respect to the total pulp, and used paper pulp and mechanical pulp are used as the remainder. The blending ratio of kraft pulp is set to 20 to 50% by weight. If it is less than 20% by weight, it is difficult to obtain the characteristics as kraft paper, and there is a risk of deviating from the standard strength standard according to JIS P 3401. This is because the blending ratio of mechanical pulp and waste paper pulp decreases when the amount is larger. In addition, the kind of kraft pulp is not specifically limited, 1 type or multiple types can be used from the kraft pulp which used conifer, hardwood, southern material, etc. as a raw material.

  By using mechanical pulp, it becomes bulky, it becomes easy to enhance smoothness by the treatment with a calendar, and a kraft wrapping paper excellent in printability can be obtained. The kind of mechanical pulp is not particularly limited, and PGW (Pressurized Grand Wood Pulp), TMP (Thermo Mechanical Pulp), RGP (Refan A Grand Pulp), GP (Grand Wood Pulp) and the like can be used. Among them, PGW and TMP are preferable because they have higher strength than other mechanical pulps and contribute to maintaining the strength of craft wrapping paper.

  The blending ratio of mechanical pulp is preferably 10 to 30% by weight with respect to the total pulp. When the amount is less than 10% by weight, the bulkiness is insufficient and sufficient smoothness cannot be obtained even when calendering is performed. When it is more than 30% by weight, the blending ratio of kraft pulp is insufficient, and the characteristics as kraft paper tend to be difficult to obtain.

  Moreover, the kind of used paper pulp is not specifically limited, For example, 1 type or multiple types can be used from all things, such as used newspaper used paper, corrugated used paper, magazine used paper, refined used paper, for example. In addition, deinking waste paper, magazine waste paper, and old waste paper in water and dedusting, then deinking pulp (DIP) obtained by chemical deinking and bleaching, and cardboard waste paper are necessary. Accordingly, waste pulp (WP) obtained by performing a pitch dispersion treatment can be used. In addition, since waste paper pulp contains many fillers, paper using waste paper pulp tends to be short of paper thickness. Therefore, paper made of waste paper pulp is insufficient in bulkiness, and even if the nip pressure of the calendar is increased, the surface smoothness cannot be sufficiently increased. However, by blending mechanical pulp, the base paper can be made bulky and the smoothness can be enhanced by increasing the nip pressure of the calendar.

  An alkyl ketene dimer (AKD) is used as the internal additive sizing agent. Since the degree of size can be increased by adding AKD, paper dust during printing and moisture wrinkles during storage can be improved. The kind of AKD is not specifically limited, For example, a stearyl ketene dimer, a behenyl ketene dimer, etc. can be used. And the addition amount of AKD shall be 0.5-5.0 kg with respect to 1t of pulp. If the amount is less than 0.5 kg / t for pulp, the effect of adding AKD is not sufficiently obtained, and if the amount is more than 5.0 kg / t for pulp, the effect corresponding to the added amount is not seen, and the slippage of the paper is large. As a result, processability deteriorates.

  The type of the paper machine is not particularly limited, but it is desirable to use a twin wire former that discharges a papermaking material between two looped wires to form a paper layer. The kind of twin wire former is not particularly limited, and for example, a gap former or a hybrid former can be used. By using the twin wire former, the difference between the front and back of the paper can be suppressed, high-quality printing can be performed on both sides of the front and back, and the difference in texture between the front and back is reduced.

  As the surface treatment agent to be externally added, oxidized starch or polyacrylamide is used. Both oxidized starch and polyacrylamide may be used. These surface treatment agents further enhance printability. Further, by using such an externally added surface treating agent in combination with the internally added sizing agent, the amount of the internally added sizing agent can be reduced, and the size can be further improved.

  This surface treatment agent is externally added by a roll transfer method in the middle of the drying process. The drying process (dryer part) is performed in a plurality of stages, usually two stages, and a surface treatment agent is externally added in the middle of each stage of the drying process. As the roll transfer type apparatus, known apparatuses such as a two-roll size press, a gate roll coater, a shim sizer, and a blade metering size press can be used.

  The form of the calender is not particularly limited, but it is desirable to use a heated soft calender having at least one nip composed of a combination of a metal roll and an elastic roll. The number of nips is not particularly limited as long as it is 1 nip or more, but in the present invention, it is usually preferably 1 to 2 nips. If the number of nips is too large, the paper may be excessively crushed and the thickness standard may not be satisfied among standards conforming to JIS P 3401. Further, when the number of nips is small, the smoothing effect is insufficient and there is a possibility that a problem occurs in printability.

  The nip pressure of the calendar is preferably 15 to 100 kN / m. If the nip pressure is too high, the paper may be excessively crushed and deviate from the standard according to JIS P 3401. On the other hand, if the nip pressure is too low, the smoothness of the surface is insufficient and the printability may be reduced.

By using a heated calendar, the surface can be made smooth while maintaining bulkiness compared to a non-heated calendar, and a paper excellent in printability and touch can be obtained.
In order to further improve this heating effect, the heating temperature of the metal roll surface is preferably 80 to 150 ° C. When the heating temperature is less than 80 ° C., the smoothing effect is insufficient and there is a possibility that a problem occurs in printability. When the heating temperature is higher than 150 ° C., yellowing due to calendering becomes noticeable.

The craft wrapping paper of the present invention is calculated from the Cobb sizing degree (g / m ² ) and the basis weight (g / m ² ) measured in JIS P 8140-1998. Is 0.1 or more and 0.25 or less. If this value is less than 0.1, the required quality of the craft wrapping paper, which is an application of the present invention, will not be satisfied, and if it exceeds 0.25, the quality will be excessive and the production cost and operability will be extremely poor.
The Cobb sizing degree is a value measured according to JIS P 8140-1998, using pure water and a contact time of 30 seconds.

〔Example〕
The effects of the present invention were verified by producing and evaluating examples and comparative examples.
All examples and all comparative examples (hereinafter also referred to as all examples) are a wire part, a press part, a (pre) dryer part, a coater (size press) part, an (after) dryer part, a calendar part, It is produced through a common papermaking process including a reel part and a winder part, and is made by making a paper with a pulp material with AKD added internally. Here, the paper part was made using a twin wire former, especially a hybrid former. Further, except for a comparative example in which no surface treatment agent was externally added, the coater part used a gate roll coater which is a roll transfer type coater to externally add the surface treatment agent. Furthermore, in all examples, a metal roll and an elastic roll (resin roll) were overlapped in the vertical direction and the number of nips was 1 nip, and a soft calender was used. The maximum nip pressure was 50 kN / m.

In all examples, softwood and hardwood kraft pulp was used as the kraft pulp, PGW (pressured ground wood pulp) was used as the mechanical pulp, and bleached magazine waste paper pulp was used as the used paper pulp. Moreover, the brand name KDG by Modern Chemical Industry Co., Ltd. was used as AKD.
As the rosin, Size Pine E-50 manufactured by Arakawa Chemical Industries, Ltd. was used.
Table 1 shows the specifications and evaluations of each example and each comparative example.

  In Comparative Example 2, paper was made under acidic paper making conditions, and in other cases, paper was made under neutral paper making conditions in both Examples and Comparative Examples.

The description in Table 1 will be described.
“Pulp blending” is the weight percent of each pulp relative to the total pulp, and the AKD addition amount is the addition amount (kg) of AKD to 1 t of pulp.
The surface treatment agent “starch” means MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd., which is an oxidized starch, and “PAM” means Haricoat G-8400 manufactured by Harima Chemicals. Further, the external addition amount of the surface treatment agent means a solid amount.
“Heating roll temperature” means the surface temperature of the metal roll of the heating calendar. In the comparative example, “non-heated” means that the heating mechanism of the heating calendar used in the examples etc. is not operated (the heating mechanism is turned off), that is, the calendar process is performed without actively heating. The conditions other than the heating temperature such as the configuration of the roller and the nip pressure are the same as those in the other examples and comparative examples. In this “non-heated” comparative example, the surface temperature of the metal roll was 30 to 50 ° C. due to spontaneous heat generation based on frictional heat and the like.

  “Cobb sizing degree” in Table 1 is measured according to JIS P 8140-1998 using pure water and a contact time of 30 seconds as described above.

  “Defect frequency” in Table 1 is the number of stains generated per 8,000 m of paper length when winding craft packaging paper with a width of 1,091 mm. ○: Less than 1; Δ1 to 2 Less than, x: 2 or more.

“Printability” in Table 1 refers to test printing using an RI tester (Ming Seisakusho), test printing at an ink tack of 22 and a printing speed of 30 m / min. Evaluation is based on the amount of paper dust generated. A: No ink unevenness and fiber peeling, ○: No ink unevenness and 1 to 3 fiber peeling, × : Ink unevenness is remarkable and fiber peeling exceeds 3 pieces. Incidentally, peeling number of fibers is the number in the region of the central portion 10cm ² of the ink transfer area.

  “Processability” in Table 1 evaluated the situation at the time of the bag making test as follows. ○: There is no problem of wrinkles and base paper slipping during bag making. ×: Wrinkling at the time of bag making, slippage of base paper, and processing impossible.

  All the examples satisfied all the standards in accordance with JIS P 3401, were relatively excellent in printability, had no problems of wrinkles and slips, and had good workability.

Claims (3)

A craft wrapping paper that satisfies a standard conforming to the quality standards of three types of craft paper defined in JIS P 3401-2000, having a standard basis weight of 50 to 120 g / m ² ,
Completion of adding 0.5 to 5.0 kg / t of alkyl ketene dimer as an internal sizing agent to a pulp raw material consisting of 20 to 50% by weight of kraft pulp and waste paper pulp and mechanical pulp Made from raw materials,
In the middle of the drying process, a surface treatment agent consisting of oxidized starch and / or polyacrylamide is externally added by a roll transfer method, and after the drying process, it is flattened by a calender having one or more nips,
It measured Cobb sizing degree in ^{JIS P 8140-1998 (g / m 2} ) and the value of the basis weight is calculated from (g / ^{m 2)} and (Cobb sizing degree / basis weight) is 0.1 to 0.25 Craft wrapping paper characterized by:   The craft wrapping paper according to claim 1, wherein the kraft wrapping paper is flattened by a heating calender having a temperature of at least one metal roll surface of 80 to 150 ° C. The craft according to claim 1 or 2, wherein the externally added surface treatment agent is oxidized starch, and its coating amount is 0.8 to 3.5 g / m ² in solid amount. wrapping paper.