JP6986348B2 - Glassine paper and method for manufacturing the glassine paper - Google Patents

Description

The present invention relates to glassine paper, and more particularly to glassine paper having excellent transparency and productivity and a method for producing the glassine paper.

Glassine paper is a thin paper that is characterized by being thinner and more transparent than ordinary paper, and is widely used for food packaging, medicine packaging, envelopes with windows, laminated paper, and the like.
In the production of glassine paper, it is necessary to reduce the gaps between pulp fibers, suppress diffused reflection of light inside the paper, and increase the transparency. Therefore, pulp with a higher degree of beating than pulp used for general paper is used. ..

Glassine paper is manufactured by a method in which the raw material, which is made by beating chemical pulp until it becomes viscous, is made into moist paper and then pressed using a heat-pressure treatment device such as a super calender to finish it. It has the advantage that it can be manufactured at a lower cost than films such as.
However, since the glassine paper has a problem that the transparency is inferior to that of films such as cellophane, it is required to improve the transparency of the glassine paper particularly in recent years.

As a method for improving the transparency of the glassine paper, for example, a method of incorporating an amphoteric starch between the pulp fibers of the base paper (Patent Document 1) or a method in which starch having a cationic group and a polysaccharide having an anionic group are mixed in advance. It has been proposed to use it as an additive for papermaking (Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-196571 Japanese Unexamined Patent Publication No. 2005-68587

However, in the case of the invention disclosed in Patent Document 1, there is a problem in productivity such that the dehydration ability in the wire part is lowered and the papermaking becomes difficult. Further, the obtained glassine paper also has a drawback that not only problems such as poor formation and a decrease in tear strength occur, but also a desired transparency cannot be obtained.
Further, the invention disclosed in Patent Document 2 is an invention aimed at improving the fixation of a sizing agent on paper, and its use on glassine paper is not even suggested.

Therefore, the present inventors diligently studied in order to solve the above-mentioned conventional drawbacks, and found that the viscosity of a 10.0% solid content aqueous solution at 25 ° C. was 30,000 mPa · s on the pulp beaten to 50 ml to 400 ml in freeness. We have found that when cationized starch having a relatively low viscosity of ~ 20,000 mPa · s is added, it is possible to obtain glassine paper having excellent productivity and transparency, and have reached the present invention.

Therefore, a first object of the present invention is to provide a highly transparent glassine paper.
A second object of the present invention is to provide a manufacturing method capable of obtaining highly transparent glassine paper with high production efficiency.

That is, the present invention comprises a base paper containing pulp beaten to 50 ml to 400 ml in freeness and cationized starch having a viscosity of a 10.0% solid content aqueous solution at 25 ° C. of 30 mPa · s to 20,000 mPa · s. was used, a glassine paper having a basis weight of ^{20.0g / m 2 ~50.0g / m 2} , [ cationized starch] in the base paper: the mass ratio of [pulp] is 0.5: 99. 5 to 3.3: 96.7 , and the glassine paper characterized by having an opacity of 20.0% or less, and the following steps (1) to (4) are included. This is a method for producing the glassine paper.
(1) The mass ratio of [cationized starch]: [pulp] of the slurry containing the pulp and the cationized starch is 0.5: 99.5 to 3.3: 96.7 , and the basis weight is. A step of preparing a sheet-shaped base paper having a temperature of 20.0 to 50.0 g / m ^2.
(2) A step of drying the base paper until the moisture content becomes less than 10.0% to obtain a roll-up paper.
(3) A step of adding water to the roll paper to obtain a wet paper containing 14.0% to 30.0% of water, and
(4) The wet paper is heat-pressure treated at 50 ° C. to 140 ° C. and a total linear pressure of 200 kg / cm to 6,000 kg / cm to have a basis weight of 20.0 g / m ^{2 to} 50.0 g / m ^2. The process of smoothing so that
In the method for producing glassine paper of the present invention, it is preferable that the thermal pressure treatment is performed using a multi-stage super calendar.

According to the present invention, it is possible to obtain a highly transparent glassine paper with high production efficiency.

The glassine paper according to the present invention has a pulp in which the freeness is beaten to 50 ml to 400 ml, and the cationized starch has a mass ratio of [cationized starch]: [pulp] of 0.5: 99.5 to 3.3 :. it using the internally added to base paper such that 96.7, a basis weight of ^{20.0g / m 2 ~50.0g / m 2} , opacity is less than 20.0% of glassine paper be.
The opacity is a numerical value measured based on JIS P8149: 2000, and the smaller the numerical value, the higher the transparency.

When the freeness of the pulp is less than 50 ml, the water-filtering property of the beaten pulp is lowered, so that the dehydration property of the papermaking base paper is lowered and the drying step takes a long time, so that the productivity is increased. Getting worse. When the freeness exceeds 400 ml, the gaps between the pulp fibers increase, so that the transparency of the obtained glassine paper deteriorates.
The freeness in the present invention means that in the Canadian standard freeness method specified in JIS P8121-2: 2012, the amount of pulp collected is changed from 3 g specified in JIS to 0.3 g, and the wire is specified in JIS. Freeness measured by changing from the screen plate to 80 mesh.

The relationship between the productivity and economies of the freeness, the basis weight of the glassine paper of the present invention ^is required to be ^{20.0g / m 2 ~50.0g / m 2} . The basis weight of less than 20.0 g / m ^2, insufficient strength as a glassine paper, basis weight is more than 50.0 g / m ^2, water drainage in the paper making process productivity is deteriorated reduced.
The basis weight is measured based on JIS P8124: 2011.

In the present invention, the reason why the cationized starch is added is that the fibers of the pulp are usually negatively charged.
That is, when the starch has a positive charge, it is easily fixed to the pulp fiber having a negative charge, and the voids of the pulp fiber are efficiently filled with the starch particles. Furthermore, by smoothing by thermal pressure treatment such as calendering, the voids between the pulp fibers are almost completely filled, and as a result, light scattering is efficiently suppressed inside the glassine paper, and the transparency of the glassine paper is reduced. improves.

In the base paper used in the glassine paper of the present invention, the mass ratio of the cationic starch with respect to the pulp is less than 0.5, hand you decrease the transparency of the glassine paper, if it exceeds 6.5 The upper limit of the mass ratio of the cationized starch is preferably 3.3 because stains are likely to occur in the base paper manufacturing process and the productivity is lowered.

Further, the viscosity range of the cationized starch needs to be 30 mPa · s to 20,000 mPa · s in an aqueous solution having a solid content of 10.0% at 25 ° C.
If the viscosity is less than 30 mPa · s, the transparency of the glassine paper is lowered, and if it exceeds 20,000 mPa · s, stains are likely to occur in the base paper manufacturing process, and the productivity is lowered.

Further, by using the cationized starch having a relatively low viscosity, it is possible to adjust the content of the cationized starch in a wide range according to the desired transparency.
The viscosity of the cationized starch was measured using a B-type viscometer (manufactured by Tokyo Keiki) under the conditions of 25 ° C. and 60 rpm.

The method for cationizing starch is not particularly limited, and examples thereof include a method in which a cationizing agent and a catalyst are reacted with starch in the presence of water or alcohol. Examples of the cationizing agent include a quaternary ammonium salt containing an epoxy group, a halohydrin compound corresponding thereto, and the like.
Further, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide may be used for cationization.

Examples of the quaternary ammonium salt containing an epoxy group include glycidyltrialkylammonium halide such as glycidyltrimethylammonium chloride, and the corresponding halohydrin compound includes 3-chloro-2-hydroxypropyltrimethylammonium chloride. And the like, 3-chloro-2-hydroxypropyltrialkylammonium halide and the like. By using any of these, a cationized starch having a quaternary ammonium group can be obtained.

Examples of the catalyst include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.
The amount of the catalyst is preferably 0.5 parts by mass to 7 parts by mass, and more preferably 1 part by mass to 3 parts by mass with respect to 100 parts by mass of starch.

Examples of the alcohol include alcohols having 1 to 4 carbon atoms. The amount of alcohol is preferably 50 parts by mass to 50,000 parts by mass, and more preferably 100 parts by mass to 500 parts by mass with respect to 100 parts by mass of starch.

The reaction temperature during cationization is usually 10 ° C to 90 ° C, preferably 30 ° C to 80 ° C. The reaction time is usually 10 minutes to 10 hours, preferably 30 minutes to 5 hours. The reaction solution may be stirred as needed during the cationization reaction.

The degree of cation group substitution of the cationized starch can be adjusted by the amount of the cationizing agent added and the composition ratio of water or alcohol. The degree of substitution with a cationic group is the number of cationic groups introduced per unit structure (glucopyranose ring) constituting the starch.

That is, the degree of cation group substitution is the average value of the number of moles of cation groups per mole of the glucopyranose ring, and is "a value obtained by dividing the number of moles of introduced substituents by the total number of moles of hydroxyl groups of the glucopyranose ring. Is defined as. Since starch has three substitutable hydroxyl groups per unit structure (glucopyranose ring), the theoretical maximum value of the degree of cation group substitution is 3 (minimum value is 0).

The degree of substitution of the cation group in the cationized starch used in the present invention needs to be 0.01 to 0.40, preferably 0.02 to 0.30, and 0.03 to 0.20. Is more preferable.
When the degree of substitution of the cation group is less than 0.01, the cationized starch cannot be sufficiently dispersed in the pulp slurry, so that the yield is deteriorated.
When the degree of substitution of cation groups exceeds 0.40, the cationized starch swells or dissolves, and the productivity deteriorates.

Here, an example of a method for measuring the degree of substitution of a cation group in the cationized starch used in the present invention will be described below.
After drying the cationized starch of the sample, the nitrogen content is measured with a total nitrogen analyzer TN-10 (manufactured by Mitsubishi Chemical Corporation). For example, when 3-chloro-2-hydroxypropyltrimethylammonium chloride is used as the cationizing agent, the degree of substitution of the cation group is 3-chloro-2 per mol of anhydrous glucose pyranose unit (molecular weight 162) in the starch molecule. -It is an average value of the number of moles of a cationic group (molecular weight 116) derived from hydroxypropyltrimethylammonium chloride, and the degree of substitution of the cationic group is calculated by the following formula.

Degree of substitution of cation group = (162 × N) / (1-116 × N)
N: Nitrogen content per 1 g of cationized starch (mol)

Examples of the raw material for the cationized starch used in the glassine paper of the present invention include starch obtained from various plants such as potato, sweet potato, tapioca, wheat, rice, and corn. Further, a starch derivative obtained by modifying these starches by acetylation, phosphoric acid esterification or the like can also be used.
Further, starch other than cationized starch, for example, amphoteric starch, grafted starch and the like can be further added as long as the quality of the glassine paper is not impaired.

The method for producing glassine paper of the present invention includes the following steps (1) to (4).
(1) The mass ratio of [cationized starch]: [pulp] of the slurry containing the pulp and the cationized starch is 0.5: 99.5 to 3.3: 96.7 , and the basis weight is. A step of preparing a sheet-shaped base paper having a temperature of 20.0 to 50.0 g / m ^2.
(2) A step of drying the base paper until the moisture content becomes less than 10.0% to obtain a roll-up paper.
(3) A step of adding water to the roll paper to obtain a wet paper containing 14.0% to 30.0% of water, and
(4) By heat-pressure treating the wet paper at 50 ° C. to 140 ° C. and a total linear pressure of 200 kg / cm to 6,000 kg / cm, the basis weight is 20.0 g / m ^{2 to} 50.0 g / m. ^The process of smoothing to 2.

In the step (1), it is possible to use a known paper machine such as a long net, a twin wire, a circular net, an inclined short net, a circular short mixing paper machine, a Yankee paper machine, and a dry type, and usually 1 It is made by layer papermaking, but it can also be made by multi-layer papermaking with two or more layers.

Further, as in the case of ordinary paper production, rosin-based sizing agents, rosin-based emulsion sizing agents and other sizing agents, polyamide epichlorohydrin and other wet paper strength agents, polyacrylamide and other dry paper strength agents, etc. Known additives can be used. In that case, the addition method may be an internal addition to the pulp slurry or an external addition by coating.

Further, in the present invention, in order to further improve the transparency, a wet paper strength agent, a water resistant agent, a lubricant, resin beads, a surface sizing agent, etc. are added to the main agent such as water resistant PVA, general PVA or styrene acrylic resin. You may apply the coating liquid containing the auxiliary agent of.

The wet paper strength agent is a polyamide epichlorohydrin resin, a polyamine epichlorohydrin resin, etc., the water resistant agent is a printability improver, etc., and the lubricant is polyethylene wax, a fatty acid ester, an acrylic resin, a resin. Examples of the surface sizing agent for beads and the like include alkyl ketene dimer (AKD) and styrene acrylic sizing agents.

The viscosity of the coating liquid is diluted to 2 mPa · s to 70 mPa · s to obtain the coating liquid from the viewpoint of improving the operability and productivity in the coating equipment such as the on-machine type size press device. Is preferable. The viscosity of the coating liquid described above is a value measured under the conditions of 35 ° C. and 60 rpm using a B-type viscometer (manufactured by Tokyo Keiki).

Examples of the device for applying the coating liquid include a gate roll coater, a two-roll size press, a rod metering size press, a bar blade coater, a blade coater, and a curtain coater. Among these, from the viewpoint that on-machine coating can be performed and the coating amount can be increased, it is preferable to use a two-roll size press or a sim sizer in the present invention.

The step (2) makes it possible to uniformly contain water in the base paper, and the step (3) makes it possible to effectively perform the subsequent thermal pressure treatment.
By the step (4), the cationized starch is tightly packed between the pulp fibers, and a highly transparent glassine paper is obtained.
The thermal pressure treatment can be performed using an apparatus such as a super calendar, a soft calendar, a hot press roll, or a multi-stage super calendar, but it is particularly preferable to use a multi-stage super calendar.
In the present invention, the (1) is the basis weight of the glassine paper after a process to ^(4), it is necessary that ^{20.0g / m 2 ~50.0g / m 2} .

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Examples and Comparative Examples]
Using kraft pulp beaten to a freeness of 40 ml using DDR as a raw material, and adding the starches shown in Table 1 internally, a base paper with a ^{basis weight of 30.0 g / m 2 is prepared with a Nagami paper machine.} Paper was made and dried with a dryer to obtain a base paper having a moisture content of 8.0%. After that, moisture was added to this base paper to make a wet paper with a moisture content of 15.0%, and supercalender treatment was performed under the conditions of 130 ° C. and a linear pressure of 250 kg / cm to obtain a glassine paper having ^{a basis weight of 30.0 g / m 2.} Obtained.

The opacity of the obtained glassine paper was measured based on JIS P8149: 2000, and the transparency was evaluated.
In addition, productivity was evaluated in the following four stages.
◯: Papermaking press rolls and papermaking dryers are not easily soiled (good productivity).
Δ: The paper press roll and paper dryer are dirty, but the time required for cleaning is within 30 minutes (production is a little difficult).
X: The size press / dryer becomes dirty within 60 minutes, and it takes 30 minutes or more to wash (production is difficult).
XX; Paper breaks occur frequently in paper machines (production is extremely difficult).
〇 in the above four-step evaluation can be produced.

澱粉Ａ：ＤＤ４２８０ 星光ＰＭＣ社製の商品名
澱粉Ｂ：ＣＡＴＯ−３０４ ナショナルスターチ社製の商品名
澱粉Ｃ：ＣＡＴＯ−３２１０ ナショナルスターチ社製の商品名 Table 1 shows the compositions and test results of each Example and Comparative Example.

Starch A: DD4280 Product name manufactured by Seiko PMC Starch B: Product name manufactured by CATO-304 National Starch Product name Starch C: Product name manufactured by CATO-3210 National Starch Co., Ltd.

As is clear from Table 1, the glassine papers of Examples 1 to 5 of the present invention all have an opacity of 20.0% or less, have good transparency, and have a comprehensive productivity evaluation of 〇. It was confirmed that it was excellent in productivity.

However, it was confirmed that when the content of the low-viscosity cationized starch was outside the range of the present invention as in Comparative Example 1 and Comparative Example 2, either productivity or transparency was lowered.
It was also confirmed that when cationized starch having a viscosity of more than 20,000 mPa · s was used as in Comparative Examples 3 to 10, either productivity or transparency was lowered.
In Comparative Example 6 and Comparative Example 10, the opacity could not be measured because the paper was cut frequently.

Since the glassine paper of the present invention has sufficient transparency, stains in the manufacturing process are reduced, and productivity is increased, it can be widely used for food packaging, medicine wrapping paper, envelopes with windows, laminated paper, and the like. It is possible and extremely useful in industry.

Claims (3)

Basis weight using a base paper containing pulp beaten to 50 ml to 400 ml in freeness and cationized starch having a viscosity of a 10.0% solid content aqueous solution at 25 ° C. of 30 mPa · s to 20,000 mPa · s. there a glassine paper ^{20.0g / m 2 ~50.0g / m 2} , [ cationized starch] in the base paper: the mass ratio of [pulp], 0.5: 99.5 to 3.3 : 96.7 , and the opacity of the glassine paper is 20.0% or less. It contains pulp beaten to 50 ml to 400 ml in freeness and cationized starch having a viscosity of a 10.0% solid content aqueous solution at 25 ° C. of 30 mPa · s to 20,000 mPa · s, and has a basis weight of 20.0 g / g. A ^{method for producing glassine paper having m 2 to} 50.0 g / m ² and an opacity of 20.0% or less, which comprises the following steps (1) to (4). Paper manufacturing method;
(1) The mass ratio of [cationized starch]: [pulp] of the slurry containing the pulp and the cationized starch is 0.5: 99.5 to 3.3: 96.7 , and the basis weight is. preparing a sheet-like base paper is ^{20.0g / m 2 ~50.0g / m 2} ,
(2) A step of drying the base paper until the moisture content becomes less than 10.0% to obtain a roll-up paper.
(3) A step of adding water to the roll paper to obtain a wet paper containing 14.0% to 30.0% of water, and
(4) The wet paper is heat-pressure treated at 50 ° C. to 140 ° C. and a total linear pressure of 200 kg / cm to 6,000 kg / cm to have a basis weight of 20.0 g / m ^{2 to} 50.0 g / m ^2. The process of smoothing so that The method for producing glassine paper according to claim 2, wherein the thermal pressure treatment is performed using a multi-stage super calendar.