JP6834575B2 - Release paper - Google Patents

Description

The present invention relates to a release paper to be used in food Applications.

A release paper that can be easily peeled off from food has been conventionally used as a laying paper attached to the bottom of a cooking sheet or a Chinese steamed bun used in manufacturing bread or cake.

Glassine paper or parchment paper is often used as the release paper. Here, the glassine paper refers to thin paper produced by highly beating chemical pulp, then making paper, and processing it with a super calender. Parchment paper refers to thin paper produced by amyloidizing the outside of cellulose by sulfuric acid processing after papermaking.

Release paper made of glassine paper or parchment paper is translucent, and by printing the manufacturer name, product name, etc. on the surface of the release paper and then attaching it to food, etc., it can be distinguished from other products. It has fulfilled the function of advertising and publicity.

As a release paper that can be used for food applications, for example, Patent Document 1 comprises a raw material pulp containing 20% by mass or more of broad-leaved bleached kraft pulp having an α-cellulose content of 90% or less as a release paper base material. Papers having light transmission having an opacity of 70% or less are disclosed.

Further, in Patent Document 2, a coating liquid containing an anionic polyacrylamide-based water-soluble resin is applied to a base paper using a specific coating machine, and the base paper is compressed and peeled off to a glassine paper obtained. A glassine release paper coated with an agent is disclosed.

Japanese Patent No. 4735271 Japanese Unexamined Patent Publication No. 10-37095

Since the release papers described in Patent Document 1 and Patent Document 2 are both supercalender-processed, it is presumed that the surface is smooth and slippery.

In general, release paper made of glassine paper or parchment paper has a smooth surface and is slippery, so that when laminating and cutting (flat plate cutting), the release papers are easily displaced from each other and difficult to handle. Therefore, there has been a demand for a release paper having excellent handleability at the time of lithographic cutting.

The present invention has been made in view of such circumstances. That is, an object of the present invention is to provide a release paper having excellent handleability at the time of lithographic cutting.

The present inventors have found that a release paper having a predetermined frictional property can be obtained by using a specific pulp raw material and making a paper under specific conditions, and have been able to reach the present invention.

That is, the present invention has the following configuration.
(1) A release paper having a base material layer and a release agent layer, the base material layer is made of wood pulp having an irregular freedom of 200 to 600 ml, and the release agent layer is made of a silicone-based release agent. A release paper having a static friction coefficient of 0.1 to 0.8 on the surface of the release agent layer and a density of 0.5 to 0.9 g / cm ^3.

(2) The release paper according to (1), which has the release agent layer on both sides of the base material layer.

(3) The release paper according to (1) or (2) above, wherein the basis weight is 20 to 80 g / m ^2.

(4) The release paper according to any one of (1) to (3) above, wherein the release agent layer has a basis weight of 0.5 to 2.0 g / m ^2.

(5) The release paper according to any one of (1) to (4) above, which is for food use.

The release paper of the present invention is excellent in handleability during lithographic cutting because the paper does not slip easily during lithographic cutting.

Hereinafter, embodiments of the present invention will be specifically described. The present invention is not construed as being limited to these embodiments.

The release paper of the present embodiment has a base material layer and a release agent layer. The release agent layer may be formed on only one side of the base material layer, or may be formed on both sides of the base material layer. When the release agent layer is formed on both sides of the base material layer, both sides can be used, and it is not necessary to confirm which surface the release agent is applied to, which is preferable.

(Base material layer)
Wood pulp is used as the pulp used for making the base material layer of the present embodiment. The wood pulp is not particularly limited, and any wood pulp used for papermaking can be used. Examples of wood pulp include chemical pulps such as broadleaf bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), broadleaf bleached sulphite pulp (LBSP), and coniferous bleached sulphite pulp (NBSP), and stone ground pulp (GP). ), Pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi-grand pulp (CGP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), etc. , Sulfite pulp, used paper pulp and the like. Considering the strength of the paper, it is preferable that the ratio of NBKP is large. In addition, synthetic fibers, non-wood fibers, and the like can be mixed with wood pulp as needed.

In the base material layer, wood pulp is the main component. Specifically, the content ratio of wood pulp in the base material layer is preferably 50 to 99.9% by mass, more preferably 70 to 99.5% by mass, and 80 to 99% by mass. Is even more preferable. If the content ratio of wood pulp in the base material layer is 50% by mass or more, papermaking can be easily performed. Further, if necessary, a paper strength enhancer, a sulfate band, a sizing agent and the like can be added.

The wood pulp constituting the base material layer is a wood pulp having an irregular freeness of 200 to 600 ml. Here, the anomalous freeness was measured by changing the pulp sampling amount from 3 g to 0.3 g and changing from the JIS standard screen plate to 80 mesh wire in the Canadian standard freeness method specified in JIS P8121: 2012. Freeness (freeness).

Wood pulp with anomalous freedom of 200 to 600 ml is a special pulp with high beating that can be obtained by crushing the pulp raw material more finely than the pulp used in ordinary papermaking. By advancing the beating process, the pulp fibers are generally short and supple, it becomes easy to obtain a high-density base material layer, and the transparency is also improved. On the other hand, when the beating process of pulp is advanced, the dehydration property is lowered and the operation efficiency is lowered. Therefore, the degree of beating is appropriately selected in consideration of the transparency, basis weight, operating efficiency, etc. of the target base material layer.

If the irregular freeness of wood pulp is less than 200 ml, the dehydration property in the papermaking process is low and the operation becomes difficult. On the other hand, if it exceeds 600 ml, the density of the base material becomes low. The anomalous freeness of wood pulp is preferably 250 to 550 ml, more preferably 300 to 500 ml.

Various beating machines such as beaters, Jordan, single disc refiners, conical refiners, cylindrical refiners, deluxe finers, double disc refiners (DDRs), medium stirring mills, and vibration mills, which are known for beating wood pulp. Can be used.

Further, the base material layer preferably has appropriate translucency. When the base material layer is translucent, when the release paper is attached to food or the like, it can be distinguished from other products and can exert functions such as advertising and promotion. Semi-transparency can be specified by the opacity specified in JIS P8149: 2000. The base material layer preferably has an opacity of 30 to 70%, more preferably 35 to 60%. If the opacity of the base material layer exceeds 70%, the transparency is low, and it becomes difficult to identify characters and patterns through the release paper. On the other hand, if the opacity of the base material layer is less than 30%, the irregular freeness is further lowered, which is not preferable in terms of operation.

In addition to wood pulp, the base material layer is for known papermaking such as fillers, sizing agents, paper strength enhancers, wet paper strength enhancers, yield improvers, pH adjusters, drainage improvers, dyes and pigments. Internal aids can be added as needed.

Examples of the filler that can be added to the base material layer include titanium dioxide, kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, gypsum, calcined kaolin, white carbon, amorphous silica, and delaminate. Examples thereof include inorganic pigments such as ted kaolin, diatomaceous earth, magnesium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, and organic pigments such as urea / formarin resin particles and fine hollow particles. The filler contained in used paper and waste paper can also be reused. In order to improve the transparency of the base material layer, it is preferable that the filler added to the base material layer is at least one selected from kaolin, talc, and calcium carbonate. The blending amount of the filler is preferably 0 to 25% by mass, more preferably 1 to 20% by mass.

The base material layer can contain a sizing agent. Since the base material layer contains a sizing agent, when the release agent coating liquid is applied to the base material layer, the release agent coating liquid does not permeate too much into the inside, and a uniform release agent layer is formed near the surface. It becomes possible to provide. Further, when the base material layer contains a sizing agent, printability can be improved.

Specific examples of sizing agents include rosin-based (anionic rosin dispersion, cationic rosin dispersion, rosin soap, etc.), alkyl keten dimer, alkenyl succinic anhydride, polyvinyl alcohol, styrene-acrylic, and higher fatty acids. Examples include rosins and petroleum resins.

The content of the sizing agent is preferably 0.3% by mass or more with respect to the base material layer. The content of the more preferable sizing agent is in the range of 0.4 to 1.5% by mass, and the content of the more preferable sizing agent is in the range of 0.5 to 1.0% by mass.

Specific examples of the paper strength enhancer and the wet strength enhancer include anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, graft copolymers of polyacrylamide and starch, various modified starches, and urea. Examples thereof include resins, polyamide / polyamine resins, polyvinyl alcohols and polyethylene oxides. In order to achieve high paper interlayer strength, at least one selected from anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, and graft copolymers of polyacrylamide and starch is preferable.

Specific examples of the yield improver include polyacrylamide compounds, polyethylene glycol compounds, polyvinyl amine compounds, polyamine compounds and the like.

Specific examples of the pH adjuster include aluminum sulfate band, aluminum chloride, aluminum sulfate, hydrochloric acid, sodium aluminate, basic aluminum compound, sodium hydroxide, potassium hydroxide, ammonia, and various primary, secondary, and tertiary pH adjusters. Examples thereof include alkaline compounds such as secondary amines. Sulfate band, sulfuric acid, and sodium hydroxide are preferable from the viewpoint of versatility and economy.

(Release layer)
In the present embodiment, the release agent layer is formed of a silicone-based release agent containing a silicone resin. Examples of the silicone resin that can be used to form the release agent layer include homopolymers or copolymers such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, and methylvinyldichlorosilane. And so on. These can be used alone or in admixture of any two or more. Further, the solution shape of the silicone resin can be used in any of solvent type, solventless type and emulsion type. Of these, the solvent-free type is preferable from the viewpoint of odor and safety.

The basis weight of the release agent layer, that is, the amount of the silicone-based release agent applied (solid content after drying) is preferably ^{0.5 to 2.0 g / m 2.} When the basis weight of the release agent layer ^{is less than 0.5 g / m 2} , the release property from foods and the like is inferior, and pinholes are generated in the release agent layer. Further, if the basis weight of the release agent layer ^{exceeds 2.0 g / m 2} , there is no difference in the release force and the manufacturing cost increases, which is not preferable. The basis weight of the release agent layer is more preferably ^{0.5 to 1.0 g / m 2.} Here, the basis weight of the release agent layer is the amount formed in the release agent layer on one side.

The coefficient of static friction on the surface of the release agent layer is 0.1 to 0.8, more preferably 0.1 to 0.6. When the coefficient of static friction on the surface of the release agent layer is within this range, the slipperiness of the release paper becomes appropriate, so that the handleability is excellent. If the coefficient of static friction on the surface of the release agent layer is less than 0.1, it becomes slippery. On the other hand, if the coefficient of static friction on the surface of the release agent layer exceeds 0.8, the unevenness of the surface becomes large, which makes it difficult to apply or print the release agent. Here, the static friction coefficient is the first static friction coefficient (first time) when the bottom surface of the weight is measured as ABS resin and the pressure applied to the bottom surface is 1.96 kPa in accordance with the horizontal method of JIS-P8147: 2010. Measured value).

(Release paper)
In the present embodiment, the release paper has a base material layer and a release agent layer, and the release agent layer may be formed on only one side of the base material layer or on both sides of the base material layer. May be.
The basis weight of the release paper is preferably from 20 to 80 g / ^{m 2,} and more preferably 20 to 50 g / ^{m 2.} If the basis weight is ^{less than 20 g / m 2} , it becomes difficult to connect the paper in the papermaking process, which makes the operation difficult. On the other hand, when the basis weight ^{exceeds 80 g / m 2} , the rigidity of the release paper is too high, the suppleness is lost, and the handleability is deteriorated. In addition, the cost becomes high.

Density of release paper is ^{0.5~0.9g / cm 3, 0.5~0.7g / cm} 3 are preferred. When the density is ^{less than 0.5 g / cm 3} , the penetration of the release agent becomes large and the release property becomes poor. In addition, the release agent may come off to the opposite surface. On the other hand, if the density ^{exceeds 0.9 g / cm 3} , the smoothness is too high, and the paper becomes slippery when the release agent is applied.

An undercoat layer may be provided between the base material layer and the release agent layer for the purpose of preventing permeation into the base material layer during coating of the release agent coating liquid and effectively exerting the peeling performance. it can. As the material constituting the undercoat layer, water-soluble resins such as polyvinyl alcohol and polystyrene-acrylic copolymer or them are used from the viewpoint of effectively preventing the permeation of the release agent coating liquid without lowering the air permeability. Aqueous emulsion is preferred. The coating amount of the undercoat layer ^{is preferably 0.2 to 2.0 g / m 2} , and more preferably 0.5 to 1.0 g / m ² .

[Manufacturing method of release paper]
(Manufacturing of base material layer)
The base material layer is usually produced by a wet papermaking method. A general method is to feed the aqueous slurry containing the predetermined wood pulp to a paper machine, disperse the pulp fibers, dehydrate, squeeze and dry the slurry, and then wind it up as a sheet. The paper machine is not particularly limited, and a known paper machine can be used as appropriate. Examples of the paper machine include a long net paper machine, a twin wire paper machine, a circular net paper machine, an on-top twin wire paper machine, a yanky paper machine, a gap former, and a hybrid former (on-top former). be able to.

The pH at the time of papermaking may be any of an acidic region (acidic papermaking), a pseudo-neutral region (pseudo-neutral papermaking), a neutral region (neutral papermaking), and an alkaline region (alkaline papermaking). After that, an alkaline agent may be applied to the surface of the paper substrate.

The drying step is usually carried out at a temperature of 90 ° C. or higher and about 120 to 140 ° C. In the drying step, a dryer such as a multi-cylinder dryer, a yanky dryer, an after dryer, a band dryer, or an infrared dryer is used.

After drying, a smoothing treatment can be performed if necessary. The smoothing process is performed on-machine or off-machine using a smoothing processing device such as a normal gloss calendar or soft calendar.

Conventionally, glassine paper and parchment paper have been used as the base material layer of the release paper. In the production of these thin papers, supercalender processing is used for the purpose of improving the smoothing of the surface after drying. However, the release paper made of the base material layer subjected to the super calender processing has a smooth surface and is slippery. Therefore, when the paper rolls of the base material layer are cut and stacked in a flat plate shape, the base material layers may be displaced from each other, making it difficult to stack the base layers at the same position.

On the other hand, in the production of the base material layer of the release paper of the present embodiment, as a general rule, supercalender processing is not used. Therefore, the surface of the base material layer is moderately rough, and when a release agent layer is provided on the base material layer to form a release paper, the coefficient of static friction on the surface of the release agent layer is within the range of 0.1 to 0.8. It can be easily controlled. As a result, when the paper rolls of the base material layer are cut and stacked in a flat plate shape, the occurrence of misalignment between the base material layers is suppressed, and it becomes easy to stack and cut at the same position. When the coefficient of static friction on the surface of the release agent layer is less than 0.1, the substrate layers are easily displaced from each other, and it is difficult to stack and cut at the same position. On the other hand, if the coefficient of static friction on the surface of the release agent layer exceeds 0.8, the smoothness of the base material is poor and the amount of the release agent applied must be increased, which is not preferable in terms of cost.

The base material layer can also be printed in order to distinguish it from other products and to advertise / promote it. Printing on the base material layer can be performed on the surface on which the release agent layer is not formed before the release agent layer is formed or after the release agent layer is formed. The printing method is not particularly limited, and various known printing methods can be applied. Examples of the printing method include various printing methods such as gravure printing, offset printing, screen printing, and UV flexographic printing.

(Formation of release agent layer)

The release agent coating liquid used for forming the release agent layer may contain a binder, a pigment, or the like in addition to the above-mentioned release agent component. Further, the release agent coating liquid may appropriately contain various auxiliary agents such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a colorant, if necessary.

The release agent layer can be formed on one side of the base material layer by applying the release agent coating liquid on one side of the base material layer and drying the release agent coating liquid through a dryer. Next, if necessary, a release agent coating solution is similarly applied to the opposite surface, and the release agent coating solution is dried through a dryer to form a release agent layer on both sides of the base material layer. can do. Further, the release agent layer may be formed on both surfaces of the base material layer at the same time.

As a method of applying the release agent coating liquid, a coating device used for manufacturing a general coating sheet can be used. Examples of coating equipment include blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coaters, curtain coaters, die slot coaters, direct gravure coaters, offset gravure coaters, multi-stage roll coaters, champlex coaters, and size presses. Examples thereof include an on-machine or off-machine coater provided with a coating device such as a coater and a gate roll coater.

Since the release paper of this embodiment is excellent in handleability at the time of flat plate cutting, it can be widely used for release paper used for protecting the adhesive surface such as an adhesive label, an adhesive sticker, and an adhesive tape. it can. In addition, it is suitable as a release paper for foods such as a cooking sheet used in manufacturing bread and cakes and a sheet of paper attached to the bottom of Chinese steamed buns.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples. In addition, unless otherwise specified, parts and% in the example indicate parts by mass and% by mass, respectively, and shall be shown in terms of solid content. The coefficient of static friction on the surface of the release agent layer was measured in accordance with JIS P 8147: 2010.

[Example 1]
(Preparation of raw materials)
Softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP) were mixed at 78/22 (solid content ratio) and then beaten to obtain a pulp slurry having an irregular freeness adjusted to 470 ml.
In this pulp slurry, 0.25 parts of wet paper strength enhancer (manufactured by Arakawa Chemical Industry Co., Ltd., polyamide / polyamine type, trade name: "Alafix 255") and 0.2 parts of yield improver per 100 parts of absolute dry pulp. (Manufactured by Hakuto Co., Ltd., polyamine type, trade name: "Polymaster R-607") was added to prepare a raw material slurry.

(Manufacturing of release paper)
This raw material slurry was made using a long net paper machine, dehydrated by a press, and dried with a multi-cylinder dryer to produce a base paper having ^{a basis weight of 30 g / m 2.} A solvent-based silicone (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to ^{both sides of the base paper as a release agent so that the basis weight on one side was 0.6 g / m 2 as the solid content after drying.} Then, it was dried to produce a release paper having a basis weight of 31 g / m ^2. The coefficient of static friction on the surface of the release layer of this release paper was 0.17, and the density was 0.62 g / cm ³ .

[Comparative Example 1]
^{In Example 1, a release paper having a basis weight of 32 g / m 2} was produced in the same manner as in Example 1 except that the base paper was dried by a multi-cylinder dryer and then subjected to supercalender treatment. The coefficient of static friction on the surface of the release layer of this release paper was 0.03, and the density was 1.06 g / cm ³ .

The release paper obtained in Example 1 was excellent in handleability. The release paper obtained in Comparative Example 1 was inferior in handleability because of its high density and low coefficient of static friction on the surface of the release agent layer.

Claims (5)

A release paper having a base material layer and a release agent layer.
The substrate layer is composed of wood pulp having an anomalous freeness of 200-600 ml.
The base material layer is not super-calender processed and
The release agent layer is made of a silicone-based release agent.
The coefficient of static friction on the surface of the release agent layer is 0.1 to 0.8.
Ri density 0.5~0.9g / cm ³ der,
Release paper for food. The release paper according to claim 1, which has the release agent layer on both sides of the base material layer. The release paper according to claim 1 or ² , wherein the basis weight is 20 to 80 g / m 2. The release paper according to any one of claims 1 to 3, wherein the release agent layer has a basis weight of 0.5 to 2.0 g / m ^2. The release paper according to any one of claims 1 to 4, wherein the base material layer has an opacity of 30 to 70% as defined by JIS P8149: 2000.