JP2008007922A - Heat-sealable packaging paper and heat-sealed package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide packaging paper having touch feeling as paper, heat-sealable on both obverse and reverse faces thereof while having waterproofness, and prevented from being broken when held by hand. <P>SOLUTION: The packaging paper is such that a waterproof layer 3 of thermoplastic resin is laminated on only one side of a blended paper layer 2 comprising pulp fiber and thermoplastic resin fiber or the blended paper is imparted with waterproofness by a sizing agent or the like. In the packaging paper, the basis weight of the blended paper layer 2 is 25-55 g/m<SP>2</SP>and the pulp fiber and the thermoplastic resin fiber account for 50-75 wt.% and 50-25 wt.% of the blended paper layer 2, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat-sealable wrapping paper and a heat-seal package.

For example, roll paper products such as toilet paper rolls and kitchen paper rolls are generally sold to consumers in a collective manner (see, for example, Patent Documents 1 and 2).
In this case, each product is generally packaged by a thermoplastic resin film 10 such as a polyethylene film in a state where a plurality of products are stacked as shown in FIGS. As a packaging form, gusset packaging, pillow packaging, or the like is adopted in addition to caramel packaging in which the film 10 is folded and wrapped in accordance with the outer shape of the packaging object 11 as shown in the figure, and the overlapping portions of the film are heat-sealed. A handle 12 formed of the same material as the packaging material is attached to the outer surface of the packaging by heat sealing, if necessary.
In the packaging material using such a thermoplastic resin film, there is a possibility that the heat seal portion may be broken, or there is a problem that cost increases when a thick film is used to avoid this. Furthermore, from the viewpoint of resource recycling, using a thermoplastic resin film has a drawback that it is difficult to reuse the material.
As a solution to this problem, a packaging material in which a thermoplastic resin layer is laminated on one side of a paper base material has been proposed (see Patent Document 3). Such a wrapping material is a very preferable wrapping material in that it has a texture as paper and is waterproof and can be heat-sealed.
However, this prior art has a problem in that the paper surfaces cannot be heat-sealed, and the packaging form is limited.
Further, from the viewpoint of the strength of the packaging material, the packaging material may be torn when the product is held in the store.
No. 3010719 JP 2005-153959 A JP 63-12410 A

  Therefore, the main problem of the present invention is to provide a wrapping paper that has a texture as paper and is waterproof, and can be heat-sealed on both front and back sides, and prevents tearing when held in the hand. There is.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
A heat-sealable wrapping paper, which is a mixed paper made of pulp fiber and thermoplastic resin fiber.

<Invention of Claim 2>
The heat-sealable wrapping paper according to claim 1, wherein a waterproof layer made of a thermoplastic resin is laminated on only one side of the mixed paper.

<Invention of Claim 3>
The heat-sealable wrapping paper according to claim 1, wherein a sizing agent or a water repellent is added to the mixed paper.

(Effects of the invention according to claims 1 to 3)
The main feature of the present invention is that a waterproof layer made of a thermoplastic resin is laminated on one side of the mixed paper, or a sizing agent, a water repellent, etc. are added to the mixed paper to provide waterproofing and mixed thermoplastic. By having a double-sided heat-sealing property with a resin fiber or a thermoplastic resin layer laminated on one side, it has a function similar to that of a conventional film packaging while having a paper texture.
Laminating a thermoplastic resin layer on both sides of a paper substrate can also provide waterproofness and heat-sealability on both sides, but in that case the texture of the paper may be impaired or it may not be disposed of as paper There is a fear. On the other hand, in the present invention, at least one of the paper surfaces is exposed, and there is no possibility that the texture of the paper is impaired.

<Invention of Claim 4>
The rice paper weight in the mixed paper is 25 to 55 g / m ² ;
The pulp fiber content in the mixed paper is 50 to 75% by weight,
The content ratio of the thermoplastic resin fiber in the mixed paper is 50 to 25% by weight.
The wrapping paper which can be heat-sealed of any one of Claims 1-3.

(Operational effect of the invention of claim 4)
In particular, by setting the blend ratio within the range described in this section, the water resistance, heat sealability, bursting strength, prevention of tearing when held in the hand, and processing suitability are all well-balanced.

<Invention of Claim 5>
Using 50 to 75% by weight of pulp fiber and 50 to 25% by weight of thermoplastic resin fiber, adding a sizing agent, and using a mixed paper having a basis weight of 25 to 55 g / m ² ,
A heat-sealed package, wherein a target sealing portion is sealed by heat sealing in a state of wrapping an article.

(Effects of invention of claim 5)
A heat seal package excellent in practical use is obtained.

<Invention of Claim 6>
The heat seal package according to claim 6, wherein the thermoplastic resin fiber is a composite fiber having a core-sheath structure in which the core is polypropylene and the sheath is polypropylene having a melting point lower than that of the core.

(Operational effect of the invention of claim 6)
For heat sealing, it can be a mixed paper with polyethylene fiber, or it can be a mixed paper with a core-sheath composite fiber whose core is polypropylene and whose sheath has a lower melting point than the core. When used, the seal strength is not always sufficient. This is because the strength of polyethylene itself is low, and even if a composite fiber is used, as long as polyethylene is used for the sheath as a binder, the strength of the polyethylene itself appears as it is and the sealing strength is low.
On the other hand, when a core-sheath composite fiber having a polypropylene core and a polypropylene sheath whose melting point is lower than that of the core is used, the strength of the polypropylene itself is higher than that of polyethylene, and the polypropylene of the sheath and the core polypropylene are bonded. Since the strength is high, even if the polypropylene of the sheath is melted, it is thought that as a result of being bonded (adhered) to the core polypropylene that still does not melt, the overall seal strength is considered to be high. Thus, a sufficiently high seal strength can be obtained.

<Invention of Claim 7>
The heat seal package according to claim 5 or 6, wherein the sizing agent is an alkyl ketene dimer.

(Operation and effect of the invention of claim 7)
By providing a waterproof layer with a thermoplastic resin on the inner surface side of the package, the package can be waterproofed. From the point of view, it is not necessarily preferable. Further, when the article to be packaged is a thin paper product such as a toilet paper roll, it has been found that the packaging layer is attached to the waterproof layer due to static electricity or the like and troubles in the packaging process are found. On the other hand, it has been found that by using a sizing agent in the external application, the same water repellency or waterproofness as in the case of providing a waterproof layer can be provided. In particular, the alkyl ketene dimer (AKD) exhibits excellent water repellency or waterproofness in the blended composition of the mixed paper of the present invention, as compared with other sizing agents, as shown in the examples described later.

  As described above, according to the present invention, if necessary, while having a texture as paper and exhibiting water repellency or waterproofness, heat sealing can be performed on both the front and back surfaces, and tearing when held in the hand is suppressed. And the like.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a cross section of a heat-sealable wrapping paper 1 according to the present invention. This wrapping paper 1 has a mixed paper layer 2 and, if necessary, a waterproof layer 3 laminated (laminated) only on one side thereof. have.

  The mixed paper layer 2 is formed by mixing pulp fibers and thermoplastic resin fibers. As pulp, NUKP (unexposed softwood kraft pulp), NBKP (softwood bleached kraft pulp), LBKP (hardwood bleached kraft pulp), BCTMP (Bleach Chemi thermomechanical pulp), TMP (thermomechanical pulp), GP (crushed wood pulp) Etc., and can be used without any particular limitation. As the thermoplastic resin fiber, PE fiber, PP fiber, PET fiber, or a composite fiber thereof can be used without particular limitation, but the core is polypropylene and the sheath is melting point than the core. It is desirable to be a composite fiber having a core-sheath structure, which is a polypropylene having a low viscosity. In such PP / PP composite fibers, the melting point of the core is preferably 150 to 170 ° C., the melting point of the sheath is preferably about 120 to 140 ° C., and the temperature difference between the melting points is 25 to 40 ° C. Desirable for.

  The blending ratio of both fibers can be determined as appropriate. The pulp fiber is more than 50 to 75% by weight (particularly 50 to 65% by weight), and the thermoplastic resin fiber is less than 50 to 25% by weight (particularly less than 50 to 35% by weight). ) Is preferred. If the ratio of the thermoplastic resin fiber is too small, the heat sealability becomes poor, and if the ratio of the pulp fiber is too small, the texture as paper may be poor or may not be discarded as a paper treatment when discarded. From this point of view, it is preferable that the wrapping paper 1 (even if it includes a waterproof layer) as a whole contains more than 50% by weight of pulp fibers because it can be disposed of as paper.

  If necessary, vinylon fibers can be mixed to improve the (rupture) strength of the mixed paper. The vinylon fiber mixing ratio is desirably 7% by weight.

  The thermoplastic resin fiber desirably has a fineness of 0.5 to 10 dtex and a fiber length of 2 to 30 mm. When the degree is less than 0.5 dtex, the adhesive strength is insufficient and sufficient paper strength cannot be obtained. When the degree exceeds 10 dtex, the number of fibers per unit weight is reduced, the adhesive strength is reduced, and sufficient paper strength is obtained. I can't get it. On the other hand, when the fiber length is less than 2 mm, the adhesive strength is insufficient, and when it exceeds 30 mm, the dispersibility in water deteriorates and the paper strength decreases. A more preferable range of the fineness is 1 to 8 dtex, and a more preferable range of the fiber length is 3 to 20 mm. Also, olefin-based synthetic pulp that is not cut fiber can be used.

  When a waterproof layer made of a thermoplastic resin layer is not provided, it is desirable to impart waterproofness to the mixed paper with a sizing agent and a water repellent. The type of sizing agent and water repellent is not limited. Examples of the sizing agent include sizing agents such as alkyl ketene dimers, styrene acrylic resins, and rosin, olefin wax water repellents, and fluorine water repellents, and alkyl ketene dimers are particularly suitable. Alkyl ketene dimers and fluorine-based water repellents have a small application amount and high waterproof / water-repellent effects, but fluorine-based water repellents are expensive and costly. The addition amount of the sizing agent is desirably 2 to 10% by weight based on the total fibers.

As a method for adding the sizing agent and / or the water repellent, external coating is preferable. In the case of internal addition, it is necessary to add a large amount in order to achieve the target waterproof property, and since there are operational problems such as foaming and machine contamination, external addition is preferable. There is no particular limitation as long as it is an external additive coating such as a size press, gate row press, calendar coating, and gravure coating.

  As the water repellent, a silicone-based, acrylic-based, urethane-based, ester-based or oil-based resin or monomer dissolved therein can be used. More specific examples include waxes such as paraffin wax and natural wax as emulsions. Waxed emulsions; Synthetic resins such as polyamide resins and polyamine resins; Fluorine resins such as polytetrafluoroethylene and polychlorotrifluoroethylene; and silicone resins such as polymethylhydrogensiloxane and polydimethylsiloxane.

  Mixing can be performed with a normal paper machine, and the sizing agent and / or water repellent is preferably added by external addition as described above. In blending, in addition to the sizing agent and the water repellent, a paper strength agent and a yield improver can be added as necessary. Paper strength agents and yield improvers include polyacrylamide resins, polyamide epichlorohydrin resins, polyethyleneimine and derivatives thereof, polyethylene oxide, polyamines, polyamides, polyamide polyamines and derivatives thereof, cationic and amphoteric starches, oxidized starch, carboxymethylated starch In addition, organic compounds such as plant gum and polyvinyl alcohol, and inorganic compounds such as sulfate band, alumina sol, colloidal silica, bentonite, and the like are used in appropriate combination.

  Fillers can also be added, such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, aluminosilicate, bentonite, etc. Such mineral fillers, organic synthetic fillers such as polystyrene particles and urea formalin resin particles, etc., can be appropriately selected and used in combination. In addition, paper additive additives such as dyes, pH adjusters, slime control agents, antifoaming agents, and stickers can be appropriately used depending on the application.

  The waterproof layer 3 provided if necessary is a water-impermeable layer made of a thermoplastic resin such as PE, PP, and PET. The material of the waterproof layer 3 is preferably the same as that of the thermoplastic resin fiber in the mixed paper layer 2, but may be different. As long as the waterproof layer 3 is impermeable, the thickness 3t is not particularly limited, but is preferably 6 μm or more. Desirably, it is 6-20 micrometers. When the thickness is less than 6 μm, the waterproof property is poor. When the thickness exceeds 20 μm, there is a problem that the waterproof paper is not easily torn when it is opened.

  In production, a known method may be employed such as producing a mixed paper using the above pulp fiber and thermoplastic resin fiber as raw materials and then laminating a thermoplastic resin film only on one side of the mixed paper.

The mixed paper is preferably 25 to 55 g / m ² . If the weight per square meter is less than 25 g / m ² , the strength is insufficient, and there is a possibility of tearing when holding the product after packaging. On the other hand, if it exceeds 55 g / m ² , the existing thermoplastic resin film packaging equipment cannot be used, or even if it can be used, the operability may deteriorate, such as increasing the heat seal temperature or reducing the processing speed. is there. In other words, the strength is insufficient if the weight is too low, and it is difficult to use existing thermoplastic resin film packaging equipment if the weight is too high.

The burst strength (JIS P 8112) of the mixed paper is preferably from 0.90 to 1.95 kgf / cm ² . The lower limit is the strength required for a packaging bag. When the upper limit is exceeded, opening becomes difficult and the cost of packaging paper increases.

  In the wrapping paper 1 thus configured, the waterproof layer 3 surface versus the waterproof layer 3 surface, the waterproof layer 3 surface versus the mixed paper layer 2 surface, and the mixed paper layer 2 surface versus the mixed paper layer 2 surface are all good. Heat sealability is demonstrated. As the packaging form, the aforementioned caramel packaging, gusset packaging, pillow packaging, or the like can be adopted.

Various wrapping papers shown in Table 1 were produced and evaluated for heat sealability, strength, waterproofness, water repellency, and processing suitability. In that case, it investigated to the effect based on the difference in the kind of size agent addition, and the effect of sizing agent addition. The results are shown in Table 1.
Pulp fiber used (NUKP (unbleached kraft pulp)), thermoplastic fiber (composite fiber: core-polypropylene (melting point 165 ° C.), sheath-core composite fiber (PP / PP) Specific examples of the composite fiber)), sizing agent and water repellent are shown in Tables 1 and 2.
Here, the heat seal strength was 170 ° C., which is close to the seal temperature when packaging PE film, and the seal time was 3 seconds. The test piece width for measuring the seal strength was 25 mm, and the peel strength was measured with Tensilon. Regarding heat-sealability, when the paper surfaces of the wrapping paper are sealed with a heat sealer and the seal portion is peeled off, the wrapping paper breaks when it is ○, peeled off (pseudo-adhesion), and what is not sealed is × did. The burst strength (JIS P8112) was also measured, and those having a burst strength of 0.90 kgf / cm ² or more were marked with ◯, and those less than that were marked with ×. In addition, as a range of bursting strength, it is preferable that it is 0.90-1.95kgf / cm < ² >. If it is less than 0.90 kgf / cm ² , it tends to be torn when it is held in the hand, and conversely if it exceeds 1.95 kgf / cm ² , there is a problem that it is difficult to tear when the wrapping paper is opened. For waterproofing, water-absorbing paper was laid under the wrapping paper, 1 ml of water colored with water-based ink was dropped, and water penetration into the water-absorbing paper was observed. As a result, the case where the water did not permeate even after standing for 1 hour or more was evaluated as ◯, and the case where the water permeated in less than 1 hour was evaluated as x. In addition to waterproofness, water repellency (JAPAN TAPPI No. 68) and heat seal strength were also measured and the results are shown in Table 2. Regarding water repellency, JAPAN TAPPI NO. It measured according to 68. In addition, regarding the suitability for packaging processing, when the rice tsubo increased, the seal temperature at the time of packaging processing was increased or the heating time was required to be x.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a wrapping paper for packaging rolled paper products such as toilet paper rolls and kitchen paper rolls.

It is sectional drawing of the wrapping paper which concerns on this invention. It is a perspective view of a toilet paper roll product. It is a perspective view of other products.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wrapping paper, 2 ... Mixed paper layer, 3 ... Waterproofing layer, 10 ... Thermoplastic resin film, 11 ... Packaging object, 12 ... Handle.

Claims (7)

  A heat-sealable wrapping paper, which is a mixed paper made of pulp fiber and thermoplastic resin fiber.   The heat-sealable wrapping paper according to claim 1, wherein a waterproof layer made of a thermoplastic resin is laminated on only one side of the mixed paper.   The heat-sealable wrapping paper according to claim 1, wherein a sizing agent or a water repellent is added to the mixed paper. The rice paper weight in the mixed paper is 25 to 55 g / m ² ;
The pulp fiber content in the mixed paper is 50 to 75% by weight,
The content ratio of the thermoplastic resin fiber in the mixed paper is 50 to 25% by weight.
The wrapping paper which can be heat-sealed of any one of Claims 1-3. Using 50 to 75% by weight of pulp fiber and 50 to 25% by weight of thermoplastic resin fiber, adding a sizing agent, and using a mixed paper having a basis weight of 25 to 55 g / m ² ,
A heat-sealed package, wherein a target sealing portion is sealed by heat sealing in a state of wrapping an article.   6. The heat seal package according to claim 5, wherein the thermoplastic resin fiber is a composite fiber having a core-sheath structure in which the core is polypropylene and the sheath is polypropylene having a melting point lower than that of the core.   The heat seal package according to claim 5 or 6, wherein the sizing agent is an alkyl ketene dimer.

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