Machine-glazed paper, method for producing the same, and envelope using the same

Abstract

To provide novel machine-glazed paper, a method for producing the same, and envelope paper using the machine-glazed paper.SOLUTION: Machine-glazed paper internally contains a rosin sizing agent having a softening point of 65°C or lower. A method for producing the machine-glazed paper comprises making the machine-glazed paper with a Yankee paper machine, wherein a rosin sizing agent having a softening point of 65°C or lower is internally added. An envelope is formed using the machine-glazed paper.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to one-sided glazed paper, a method for manufacturing the same, and an envelope using the one-sided glazed paper. [Background technology]

[0002] Single-sided glossy paper is paper that has excellent gloss and smoothness on only one side. Single-sided glossy paper is usually printed on only the glossy side and is used for packaging materials, posters, bag materials, etc. One-sided glossy paper is made using a Yankee paper machine equipped with a Yankee dryer with a mirror-finished surface. By attaching a wet paper to the Yankee dryer with a touch roll and drying it, gloss and smoothness are imparted only to the side attached to the dryer.

[0003] Single-sided glossy paper is generally made by acidic papermaking to ensure adhesion to a Yankee dryer, but acidic papermaking poses problems with long-term storage of paper. Therefore, a method for making single-sided glossy paper using neutral papermaking has been sought. For example, Patent Document 1 proposes single-sided glossy paper made on a papermaking machine equipped with a Yankee dryer, in which a neutral rosin sizing agent is added to the raw pulp and a polyacrylamide resin is added internally and / or externally to the raw pulp, the paper surface pH of the glossy side is set to 5.5 to 8.0, and the 75° specular white paper gloss of the glossy side conforming to JIS P 8142 is 25 to 40%. In Patent Document 1, the polyacrylamide resin is used to improve adhesion to the dryer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-138294 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a novel one-sided glossy paper that is optimal for envelope applications and a method for producing the same. [Means for solving the problem]

[0006] The means for solving the problems of the present invention are as follows. 1. One-sided glossy paper characterized by the incorporation of a rosin sizing agent with a softening point of 65°C or less. 2. One-sided glazed paper according to 1., characterized in that the pH of hot water extraction is 6.0 to 8.0. 3. One-sided glazed paper according to 1. or 2., characterized in that the ash content is 5% or less. 4. One-sided glossy paper according to any one of 1. to 3., characterized in that the rosin sizing agent is anionic. 5. One-sided glossy paper according to any one of 1. to 4., characterized in that it does not contain calcium carbonate as a filler. 6. One-sided glossy paper according to any one of 1. to 5., characterized in that the Stockigt sizing degree of the glossy surface is 2 seconds or more. 7. Made on a Yankee paper machine A method for producing one-sided glazed paper, characterized in that the paper stock contains a rosin sizing agent having a softening point of 65°C or less. 8. The method for producing one-sided glossy paper according to 7., characterized in that the inlet pH is 5.5 to 8.0. 9. An envelope made of one-sided glossy paper as described in any of 1. to 6. 10. The envelope according to claim 9, characterized in that a portion of the envelope has a transparent window impregnated with a transparency agent. [Effects of the Invention]

[0007] The present invention provides a novel one-sided glossy paper that exhibits good paper release from the Yankee dryer during papermaking, and a method for producing the same. Good paper release from the Yankee dryer prevents the occurrence of lumps and uneven gloss on the paper surface, enabling the production of one-sided glossy paper with an excellent gloss surface appearance. Single-sided glazed paper with a hot water extraction pH of 6.0 to 8.0 is less susceptible to deterioration and can be stored for a long period of time. Single-sided glazed paper with an ash content of 5% or less or that does not contain calcium carbonate as a filler adheres well to the Yankee dryer during papermaking and has a more beautiful glossy surface. Anionic rosin sizing agents have excellent adsorption to pulp, particularly in papermaking systems in the weakly acidic to neutral range, and can produce one-sided glossy paper that has a beautiful glossy surface and is excellent in resistance to deterioration. Furthermore, the one-sided glossy paper of the present invention is excellent in printability, suitability for bag-making, and suitability for processing with a viewing window, so that envelopes that are beautiful after printing and can be stored for a long period of time can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0008] The one-sided glossy paper of the present invention contains a rosin sizing agent with a softening point of 65°C or less. The one-sided glossy paper is a paper (JIS P0001 6180) in which a wet paper is attached to a Yankee dryer with a mirror-finished surface using a touch roll during the drying process, and then dried, thereby imparting gloss and smoothness to only the side attached to the dryer. It is preferable that the Oken smoothness of the non-glossy side of the one-sided glossy paper is less than 20 seconds, and that the Oken smoothness of the glossy side is at least 40 seconds greater than that of the non-glossy side. In this specification, the expression "A to B (A and B are numerical values ​​or ratios)" means a numerical range that includes both ends.

[0009] One-sided glazed paper is a sheet made of papermaking fibers, fillers, various auxiliaries, and the like. The papermaking fiber is preferably wood pulp. Examples of wood pulp include chemical pulps such as softwood kraft pulp, hardwood kraft pulp, and sulfite pulp; mechanical pulps such as thermomechanical pulp, stone-grind pulp, and refiner-grind pulp; and recycled paper pulp obtained from newspaper, coated paper, and fine paper. These wood pulps can be used alone or in combination. If necessary, one or more non-wood pulps such as kenaf, hemp, and bamboo, as well as fiber materials other than cellulose fibers such as glass fiber and polyethylene fiber can be blended.

[0010] From the standpoint of strength of the single-sided glossy paper, it is preferable that the wood pulp content of all papermaking fibers be 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and most preferably 100% by mass. Although recycled paper pulp can be added to reduce costs and promote recycling, recycled paper pulp often contains a lot of ash, such as calcium carbonate, which inhibits adhesion to the Yankee dryer. Therefore, when recycled paper pulp is added, its type and content are adjusted so that the ash content (JIS P8251:2003) of the resulting single-sided glazed paper is low, for example, 5% or less. The amount of recycled paper pulp added relative to the total papermaking fiber can be adjusted depending on the ash content of the recycled paper pulp, but can be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, etc.

[0011] The one-sided glossy paper may contain a filler. Examples of fillers that can be used include known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, zeolite, and synthetic resin fillers. As mentioned above, calcium carbonate inhibits adhesion to the Yankee dryer, so if a filler is used, it is preferable to use one other than calcium carbonate. In the present invention, the filler is an optional component, and the paper may be free of fillers.

[0012] The one-sided glazed paper of the present invention contains a rosin sizing agent with a softening point of 65°C or less as an internal sizing agent. Wet paper containing a rosin sizing agent with a softening point of 65°C or less exhibits good paper release from a Yankee dryer during papermaking, and one-sided glazed paper with excellent gloss surface beauty can be produced. The softening point of the rosin sizing agent is preferably 64°C or less, more preferably 63°C or less, even more preferably 62°C or less, even more preferably 61°C or less, and even more preferably 60°C or less. In this specification, softening point refers to the value measured according to JIS K5902-1969.

[0013] The rosin sizing agent having a softening point of 65° C. or less is preferably a neutral rosin sizing agent or a weakly acidic rosin sizing agent. By using a neutral rosin sizing agent or a weakly acidic rosin sizing agent, it becomes easier to obtain one-sided glossy paper that is less susceptible to discoloration and deterioration over time. The rosin sizing agent having a softening point of 65°C or less is preferably anionic. As will be described in detail below, the one-side glossy paper of the present invention preferably has a hot water extraction pH (JIS P8133-2:2013) of 6.0 to 8.0 in order to prevent deterioration. Anionic rosin sizing agents have excellent adsorption to pulp, particularly in papermaking systems in the weakly acidic to neutral range suitable for producing paper with a hot water extraction pH of 6.0 to 8.0.

[0014] The amount of rosin sizing agent with a softening point of 65°C or less is not particularly limited as long as the effects of the present invention are achieved, but for example, an amount of 0.01 to 0.3 parts by mass per 100 parts by mass of papermaking fibers is preferred from the viewpoint of paper releasability from a Yankee dryer. The amount of rosin sizing agent with a softening point of 65°C or less per 100 parts by mass of papermaking fibers can be 0.03 to 0.05 parts by mass, 0.25 to 0.2 parts by mass, or 0.2 parts by mass or less.

[0015] The single-sided glazed paper of the present invention may contain known auxiliary agents. However, since the single-sided glazed paper of the present invention contains a rosin sizing agent with a softening point of 65°C or less, which provides sufficient paper releasability from the Yankee dryer, it is not necessary to contain an excessive amount of polyacrylamide, which would improve adhesion to the Yankee dryer. Therefore, the polyacrylamide content of the entire single-sided glazed paper is preferably 0.1% by mass or less, more preferably 0.08% by mass or less, even more preferably 0.05% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.01% by mass or less.

[0016] Any known internal additives can be used without limitation, and examples thereof include aluminum sulfate and various anionic, cationic, nonionic, or amphoteric retention aids, drainage aids, paper strength agents, dyes, fluorescent whitening agents, pH adjusters, antifoaming agents, pitch control agents, and slime control agents.

[0017] The one-sided glossy paper of the present invention may contain a sizing agent other than a rosin sizing agent having a softening point of 65°C or less, but the proportion of the rosin sizing agent having a softening point of 65°C or less to the total sizing agent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and most preferably 100% by mass.

[0018] Examples of external additives include known external additives such as polyacrylamide, polyvinyl alcohol, surface sizing agents, starch, latex, water-resistant agents, water-retaining agents, thickeners, and lubricants, and these may be used alone or in combination of two or more. However, in the case of polyacrylamide, the content is preferably not more than the above-mentioned amount. The method for surface treatment with an external additive auxiliary is not particularly limited, but known coating devices such as a rod metering size press, a pond type size press, a gate roll coater, a spray coater, a blade coater, and a curtain coater can be used. The amount of external coating is not particularly limited, but is preferably 0.1 to 3.0 g / m2 in solid content per side. 2 is preferable, and 0.2 to 2.0 g / m 2 is more preferred.

[0019] There is no particular restriction on the basis weight of single-sided glossy paper, but it is recommended that it be 15 g / m 2 More than 200g / m 2 The basis weight of single-sided glossy paper is 15 g / m 2 If the paper is less than this, it may not be strong enough. 2 If it exceeds this limit, it will be heavy and transportation costs will increase.

[0020] The density of single-sided glossy paper is 0.5 to 0.9 g / cm 3 is preferable, and 0.55 to 0.85 g / cm 3 More preferably, the density is 0.5 g / cm 3 If the density is less than 0.9 g / cm, the strength of the single-sided glossy paper may decrease. 3 If the temperature exceeds this range, it may become difficult for the transparentizing agent to penetrate into the one-sided glossy paper.

[0021] The single-sided glossy paper of the present invention preferably has an Oken smoothness of less than 20 seconds on the non-glossy side, and an Oken smoothness of the glossy side that is at least 40 seconds greater than that of the non-glossy side. The Oken smoothness of the glossy side of the single-sided glossy paper of the present invention is preferably at least 50 seconds, more preferably at least 60 seconds, even more preferably at least 70 seconds, and even more preferably at least 80 seconds. In particular, single-sided glossy paper with an Oken smoothness of the glossy side of 50 seconds or more has excellent printability on the glossy side, and, for example, reduces printing unevenness when used to produce envelopes with the glossy side as the outer surface.

[0022] In the one-sided glossy paper of the present invention, the 75 degree gloss (JIS P8142:2005) of the glossy side is preferably 20% or more, more preferably 21% or more, and even more preferably 22% or more. From the viewpoint of paper release from a Yankee dryer, the Stockigt sizing degree (JIS P8122:2004) of the glossy side of one-sided glossy paper is preferably 2 seconds or more, more preferably 3 seconds or more, even more preferably 4 seconds or more, and even more preferably 5 seconds or more.

[0023] The hot water extraction pH (JIS P8133-2:2013) of single-sided glossy paper is preferably 6.0 to 8.0 from the viewpoint of suppressing deterioration of the single-sided glossy paper, more preferably 6.2 or higher, even more preferably 6.4 or higher, and even more preferably 6.6 or higher. The air resistance (JIS P8117:2009) of the one-sided glossy paper can be set to, for example, 1 to 150 seconds depending on the application.

[0024] For the one-sided glossy paper of the present invention, particularly for envelope applications, the air resistance is preferably 5 to 40 seconds from the viewpoint of suitability for bag-making and window-fitting processes. If the air resistance is less than 5 seconds, the clarifying agent may not penetrate during window-fitting processes, potentially resulting in poor transparency of the window. Furthermore, when envelope paper is stacked before bag-making, air may accumulate between the sheets, causing the sheets to become uneven and resulting in clogging of the bag-making machine during bag-making. On the other hand, if the air resistance exceeds 40 seconds, the paper strength may decrease, potentially resulting in paper tearing during bag-making or printing.

[0025] The ash content of single-sided glossy paper is preferably 5% or less (JIS P8251:2003), because this improves paper release from the Yankee dryer and makes it easier to obtain single-sided glossy paper with excellent gloss and smoothness on the glossy surface. The ash content of single-sided glossy paper is more preferably 3% or less, even more preferably 2% or less, even more preferably 1% or less, even more preferably 0.5% or less, and most preferably 0.3% or less.

[0026] The one-side glazed paper of the present invention is made by a Yankee paper machine equipped with a Yankee dryer. The papermaking method for the Yankee paper machine is not particularly limited, and known Fourdrinier formers, on-top hybrid formers, gap formers, etc. can be used. Paper can be made using acidic, neutral, or alkaline papermaking methods, but in order to prevent discoloration and deterioration of one-sided glossy paper over time, it is preferable that the stock inlet pH be 5.5 to 8.0. The stock inlet is a facility in a papermaking machine that injects raw material onto the wire in a uniform manner in both width and flow direction, and has a significant impact on paper formation and other qualities.

[0027] The single-sided glossy paper of the present invention has excellent paper strength and high dimensional stability, and can be used for packaging purposes such as envelopes, heavy-duty bags, small bags, square-bottom bags, carrier bags, patterned paper, insulation wrapping paper, food wrapping paper, general wrapping paper, medical and cosmetic packaging, miscellaneous packaging, industrial materials, etc., as well as various processing purposes such as lamination and aluminum lamination. Among these, packaging purposes, especially envelopes, are preferred because of their excellent long-term storage stability, high gloss surface, printability, and aesthetic appeal.

[0028] The envelope using the one-sided glossy paper of the present invention can have a viewing window. The viewing window is formed by impregnating at least a portion of the one-sided glossy paper with a clarifying agent. One-sided glossy paper has a glossy side and a non-glossy side, and when impregnating with the clarifying agent, it is preferable to impregnate the non-glossy side first, as this has excellent permeability and does not impair the smoothness of the glossy side.

[0029] Examples of clarifying agents include clarifying resins such as acrylic resin, polyethylene resin, polyester resin, urethane resin, nitrocellulose, shellac, and rosin, vegetable oils such as tung oil, linseed oil, castor oil, hydrophilic castor oil, coconut oil, soybean oil, and commercially available salad oil, and waxes such as carnauba wax, palm wax, beeswax, spermaceti, and Japan wax. These clarifying agents can be used alone or in combination of two or more. Among these, a clarifying resin that is stable over time is preferred, an acrylic resin is more preferred, and an ultraviolet-curable acrylic resin is even more preferred. [Example]

[0030] The present invention will be specifically illustrated by the following examples, but the present invention is not limited to the descriptions in the examples. Furthermore, parts by mass in the examples refer to parts by mass on an bone-dry basis unless otherwise specified.

[0031] "Making one-sided glossy paper" LBKP (CSF 450 mL) and NBKP (CSF 550 mL) were used. Deinked pulp was used as the recycled paper pulp. A paper stock was prepared by mixing papermaking fibers and internal additives in the proportions (parts by mass) shown in Table 1. The obtained paper stock was made into paper using a Fourdrinier Yankee paper machine to obtain one-side glazed paper.

[0032] "Evaluation Method" The obtained one-sided glossy paper was evaluated as follows, and the results are shown in Table 1. Basis weight Measurements were taken in accordance with JIS P8124:2011. Paper thickness, density Measurements were taken in accordance with JIS P8118:2014. Smoothness (Ouken style) Measurements were taken in accordance with JIS P8155:2010.

[0033] Air resistance Measurements were taken in accordance with JIS P8117:2009. 75 degree gloss The glossy surface was measured in accordance with JIS P8142:2005. ash Measurements were taken in accordance with JIS P8251:2003. whiteness The glossy surface was measured in accordance with JIS P8148:2018. Stöckigt size Measurements were taken in accordance with JIS P8122:2004. Hot water extraction pH Measurements were taken in accordance with JIS P8133-2:2013.

[0034] glossy surface The glossy surface was visually inspected under fluorescent light and evaluated according to the following criteria: ◯ or Δ indicates no practical problems. [Good: No unevenness on the glossy surface, Fair: Some unevenness but no practical problems, Bad: Many unevennesses] High temperature and humidity accelerated test After an accelerated test in which the product was left in a high temperature and humidity environment (40°C, 85%) for 20 days, the presence or absence of local discoloration on the glossy surface was checked according to the following criteria. If the evaluation was good, there was no problem in practical use. [〇: No discoloration on glossy surface, ×: Discoloration present]

[0035] [Table 1]

[0036] The one-sided glossy papers obtained in Examples 1 to 7 using a rosin sizing agent with a softening point of 65°C or less according to the present invention had good paper release from the Yankee dryer and excellent glossy surface properties, making them particularly suitable for envelope paper. In the one-sided glossy paper obtained in Comparative Example 1, which used an AKD (alkylene ketene dimer) sizing agent with a softening point of 45°C, and in Comparative Examples 2 and 3, which used rosin sizing agents with softening points of over 65°C, the sizing agent did not show any effect at a sizing degree of 1 second, and the surface of the glossy side was uneven, making it practically unsuitable for use as envelope paper, etc. This confirms that by using a rosin sizing agent with a softening point of 65°C or less, it is possible to obtain one-sided glossy paper with excellent glossy surface quality. Furthermore, the one-sided glossy papers obtained in Examples 1 to 4 and Comparative Examples 1 to 3, in which the hot water extraction pH was 6.0 to 8.0, were able to suppress discoloration over time.

Claims

1. This one-sided glossy paper is characterized by having a rosin sizing agent with a softening point of 65°C or less added thereto.

2. 2. The one-sided glossy paper according to claim 1, characterized in that the pH of hot water extraction is 6.0 to 8.

0.

3. 3. The one-sided glazed paper according to claim 1, wherein the ash content is 5% or less.

4. 3. The one-sided glossy paper according to claim 1, wherein the rosin sizing agent is anionic.

5. 3. The one-sided glazed paper according to claim 1, wherein the filler is not calcium carbonate.

6. 3. The one-sided glossy paper according to claim 1, wherein the glossy surface has a Stockigt sizing degree of 2 seconds or more.

7. It is made on a Yankee paper machine, A method for producing one-sided glazed paper, characterized in that the paper stock contains a rosin sizing agent having a softening point of 65°C or less.

8. The method for producing one-sided glossy paper according to claim 7, characterized in that the inlet pH is 5.5 to 8.

0.

9. An envelope made of the one-side glossy paper according to claim 1 or 2.

10. 10. The envelope according to claim 9, wherein a part of the envelope has a viewing window impregnated with a transparency agent.

Images