WO2023186116A1

WO2023186116A1 - Paper layer and packaging sheet, and manufacturing methods therefor, packaging sleeve and packaging container

Info

Publication number: WO2023186116A1
Application number: PCT/CN2023/085549
Authority: WO
Inventors: 宋强; 朱向阳; 邹义龙
Original assignee: 康美包服务股份公司; 康美包（苏州）有限公司
Priority date: 2022-04-01
Filing date: 2023-03-31
Publication date: 2023-10-05
Also published as: TW202403145A

Abstract

A paper layer and a packaging sheet, and manufacturing methods therefor, a packaging sleeve and a packaging container. The paper layer comprises, in the thickness direction thereof, a first layer, a second layer, and an intermediate layer located between the first layer and the second layer, which layers are arranged in a stacked manner, wherein the first layer, the intermediate layer and the second layer all comprise a chemical wood pulp; the chemical wood pulp comprises a first chemical fiber pulp containing first fibers and a second chemical fiber pulp containing second fibers, the fiber length of the first fibers being greater than the fiber length of the second fibers; and the content of the first chemical fiber pulp of at least one of the second layer and the first layer is higher than the content of the first chemical fiber pulp of the intermediate layer. By using the paper layer, the phenomenon of missing packaging of a packaging container can be reduced or even eliminated, and the quality of a packaged product is improved.

Description

Paper layers and packaging sheets and respective manufacturing methods, packaging sleeves and packaging containers

Cross-references to related applications

This application is based on and claims priority from Chinese Patent Application No. 202210347049.9, titled "Composite Sheet for Packaging and Manufacturing Methods, Packaging Sleeves and Packaging Containers", submitted on April 1, 2022, and on November 25, 2022. The priority of Chinese patent application No. 202211493658.1, titled "Paper Layer and Manufacturing Method, Composite Sheet for Packaging, and Packaging Container" submitted on 2019-01-28 .

Technical field

Embodiments of the present disclosure relate to a paper layer of a packaging composite sheet and a manufacturing method thereof, a packaging composite sheet and a manufacturing method thereof, a packaging sleeve and a packaging container.

Background technique

Typically, packaging sheets used to form packaging containers are formed from multiple laminate layers including, but not limited to: paper layers for support, barrier layers for water and oxygen barrier, and layers for printing. Pattern layer, encapsulation layer for sealing, etc.

In the process of forming the packaging container, the packaging sheet is first folded along a predetermined crease line to form a packaging sleeve with openings at both ends; then, one of the openings is sealed to form the top of the packaging container and passed through the opening at the other end. Filling is carried out; after the filling is completed, the other end opening is sealed to finally form a packaging container containing the contents. If the performance of the packaging sheet is poor, the resulting packaging container is prone to leakage (or package leakage), which affects the quality of the packaged product.

Contents of the invention

Embodiments of the present disclosure provide a paper layer of a packaging composite sheet and a manufacturing method thereof, a packaging composite sheet and a packaging container, which can reduce or even eliminate the leakage phenomenon of packaging containers and improve the quality of packaging products.

According to a first aspect of the present disclosure, a paper layer of a packaging composite sheet is provided. The paper layer includes, in its thickness direction, a first layer and a second layer that are laminated and located between the first layer and the second layer. layer an intermediate layer therebetween, wherein the first layer, the intermediate layer and the second layer all include wood chemical pulp, and the wood chemical pulp includes a first fiber chemical pulp having a first fiber and a second fiber chemical pulp. a second fiber chemical slurry of fibers, the fiber length of the first fiber being greater than the fiber length of the second fiber; wherein, the first fiber chemical pulp of at least one of the second layer and the first layer The content is higher than the content of the first fiber chemical pulp in the middle layer.

In at least some embodiments, the first fiber is softwood fiber, and the first fiber chemical pulp is sulfate softwood chemical pulp; the sulfate needle of at least one of the second layer and the first layer is The content of leaf chemical pulp is higher than the content of sulfate needle chemical pulp in the middle layer.

In at least some embodiments, the content of the sulfate softwood chemical pulp in the second layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and the sulfate softwood chemical pulp in the second layer The mass percentage of the second layer is greater than or equal to 70%.

In at least some embodiments, the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is greater than or equal to 85%.

In at least some embodiments, the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is 100%.

In at least some embodiments, the content of the sulfate softwood chemical pulp in the first layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and the sulfate softwood chemical pulp in the first layer The mass percentage of the first layer is greater than or equal to 70%.

In at least some embodiments, the content of the first layer of kraft softwood chemical pulp is equal to the content of the second layer of kraft softwood chemical pulp.

In at least some embodiments, the sulfate needle chemical pulp in the first layer accounts for 75% to 85% of the mass of the first layer; the sulfate needle chemical pulp in the second layer accounts for all The mass percentage of the second layer is 75% to 85%.

In at least some embodiments, the content of the first layer of sulfate softwood chemical pulp is lower than the content of the second layer of sulfate softwood chemical pulp.

In at least some embodiments, the sulfate needle chemical pulp in the first layer accounts for 75% to 85% of the mass of the first layer; the sulfate needle chemical pulp in the second layer accounts for all The mass percentage of the second layer is 95% to 100%.

In at least some embodiments, the grammage of the at least one of the second layer and the first layer is 19% to 30% of the total grammage of the paper layer.

In at least some embodiments, the second fiber is hardwood fiber, and the second fiber chemical pulp is sulfate hardwood chemical pulp; in each of the first layer, the middle layer and the second layer In one layer, the content of the second fiber chemical pulp is lower than the content of the first fiber chemical pulp.

In at least some embodiments, the middle layer further includes wood mechanical pulp or wood mechanochemical pulp; neither the second layer nor the first layer contains the wood mechanical pulp and the wood mechanochemical pulp.

In at least some embodiments, the middle layer further includes the wood mechanical pulp; the wood mechanical pulp includes a second fiber mechanical pulp having a second fiber; the second fiber is a hardwood fiber, and the second fiber Mechanical pulp is broadleaf mechanical pulp.

In at least some embodiments, the mass percentage of the broadleaf mechanical pulp in the middle layer of the middle layer is 40% to 50%.

In at least some embodiments, the mass percentage of the broadleaf mechanical pulp in the middle layer of the middle layer is 43% to 48%.

In at least some embodiments, the paper layer of the packaging composite sheet further includes: a coating layer. In the thickness direction of the paper layer, the coating layer is stacked with the first layer and is located opposite to the middle layer. one side, wherein the coating is configured to have a printed pattern.

In at least some embodiments, the coating includes inorganic non-metallic materials.

In at least some embodiments, the inorganic non-metallic material includes china clay.

In at least some embodiments, the coating has a basis weight of 6% to 9% of the total basis weight of the paper layer.

In at least some embodiments, the thickness of the coating is 4% to 5% of the total thickness of the paper layer.

According to a second aspect of the present disclosure, a composite sheet for packaging is provided, including the aforementioned paper layer.

In at least some embodiments, the packaging composite sheet includes inner and outer surfaces opposite in its thickness direction, the first layer of the paper layer is disposed close to the outer surface, and the second layer of the paper layer The layer is arranged close to the inner surface, and the packaging composite sheet further includes: a sealing layer, which is stacked with the second layer of the paper layer in the thickness direction of the paper layer, and Located on the side opposite to the middle layer, the sealing layer is configured to seal the packaging composite sheet under the action of thermal activation or ultrasonic activation.

According to a third aspect of the present disclosure, a packaging container is provided, including the aforementioned packaging composite sheet.

According to a fourth aspect of the present disclosure, a method for manufacturing a paper layer of a packaging composite sheet is provided, including: forming a paper layer; wherein the forming a paper layer includes: forming a first layer, a second layer, and a second layer located on the third layer. an intermediate layer between one layer and the second layer, wherein the first layer, the intermediate layer and the The second layers each include wood chemical pulp, and the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, and the fiber length of the first fibers is greater than that of the third fibers. The fiber length of the two fibers; wherein the content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer.

In at least some embodiments, forming the first layer, the second layer, and the intermediate layer between the first layer and the second layer includes: providing wet pulp, adding starch and/or to the wet pulp or dry strength agent; and applying the wet pulp to the forming device and drying.

In at least some embodiments, only dry strength agent is added to the wet pulp, and the dosage of the dry strength agent is 5 to 10 kg/t.

According to a fifth aspect of the present disclosure, there is provided a composite sheet for packaging, including a paper layer and a sealing layer, the sealing layer being disposed on a first side of the paper layer in the thickness direction of the composite sheet for packaging. , wherein the internal bonding strength of the paper layer is 190-230J/m ² .

In at least some embodiments, the raw material of the paper layer is dry pulp, and the internal bonding strength of the paper layer is 210-230 J/m ² .

In at least some embodiments, the paper layer has a density of 700-760 kg/m ³ . Further, for example, the density of the paper layer is 720-750kg/m ³ .

In at least some embodiments, the thickness of the paper layer is 275-295 μm. Further, for example, the thickness of the paper layer is 280-290 μm.

In at least some embodiments, the paper layer has a basis weight of 205-218 g/m ² .

In at least some embodiments, the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.3-0.8cm ³ /(m ² ·24h·0.1MPA). Further, for example, the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.5-0.6cm ³ /(m ² ·24h·0.1MPA).

In at least some embodiments, the packaging composite sheet has a dust level of less than 10 g for forming 1000 packages.

In at least some embodiments, the paper layer is composed of three fiber layers.

In at least some embodiments, the packaging composite sheet further includes a barrier layer, which is disposed on the first side of the paper layer in the thickness direction of the packaging composite sheet and located between the paper layer and the Sealing layers are provided between and/or on a second side of the paper layer opposite the first side.

In at least some embodiments, the material of the sealing layer is a heat-activatable high-molecular polymer or an ultrasonic-activatable high-molecular polymer; the material of the barrier layer is selected from high-molecular polymers, metal oxides, non- At least one of metal oxides and metals.

According to a sixth aspect of the present disclosure, a packaging sleeve is provided, including the packaging composite sheet as described above.

According to a seventh aspect of the present disclosure, a packaging container is provided, including the packaging composite sheet as described above.

According to an eighth aspect of the present disclosure, there is provided a manufacturing method of a composite sheet for packaging, including: forming a paper layer, including: providing wet pulp; and applying the wet pulp to a forming device and drying to form the paper layer; and Forming a sealing layer, the sealing layer is formed on the first side of the paper layer in the thickness direction of the packaging composite sheet, wherein the forming the paper layer further includes: controlling the internal bonding of the paper layer Strength such that the internal bonding strength of the paper layer is 210-230 J/m ² .

In at least some embodiments, the providing wet pulp includes: providing dry pulp, breaking up the dry pulp and diluting it with a solution to obtain the wet pulp; and the method further includes: controlling the internal bonding strength of the paper layer to The internal bonding strength of the paper layer is 210-230J/m ² .

In at least some embodiments, the internal bonding strength of the paper layer is controlled by at least one of the following methods: Method 1: Controlling the beating degree of the wet pulp; Method 2: Controlling the soft pulp in the wet pulp and broadleaf pulp; Mode 3: Control the amount of starch and/or dry strength agent added to the wet pulp; and Mode 4: Control the amount of starch and/or dry strength agent applied between the fiber layers of the paper layer. or the amount of dry strength agent.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure and do not limit the present disclosure. .

Figure 1 is a photo of the top appearance of a packaging container;

Figure 1A is a cross-sectional photograph taken along line A-A in Figure 1;

Figure 2 is a photo of the appearance of the top ear flap of another packaging container;

Figure 2A is a partial photo of the inner surface of the ear wing in Figure 2;

Figure 2B is a partially enlarged photo of the inner surface of the ear wing in Figure 2A;

Figure 3 is a schematic plan view of a packaging composite sheet according to an embodiment of the present disclosure;

Figure 3A is a schematic cross-sectional view taken along line B-B of Figure 3;

Figure 4 is a schematic structural diagram of a packaging sleeve according to an embodiment of the present disclosure;

Figure 5 is a schematic structural diagram of a packaging container according to an embodiment of the present disclosure;

Figure 5A is a schematic cross-sectional view taken along line C-C of Figure 5;

Figure 6 is another schematic cross-sectional view taken along line B-B of Figure 3;

Figure 7 is a method for manufacturing the paper layer of the packaging composite sheet according to the embodiment of the present disclosure;

Figure 8 is a cross-sectional photograph of the top seal of the packaging container according to an embodiment of the present disclosure;

Figure 9 is a cross-sectional photograph of the top seal of a packaging container according to another embodiment of the present disclosure;

Figure 10A is a schematic plan view 1 of a packaging composite sheet according to an embodiment of the present disclosure;

Figure 10B is a schematic cross-sectional view taken along line A-A of Figure 10A;

Figure 11 is a second schematic plan view of a packaging composite sheet according to an embodiment of the present disclosure;

Figure 12 is a schematic plan view three of a packaging composite sheet according to an embodiment of the present disclosure;

Figure 13 is a schematic plan view 4 of a composite sheet for packaging according to an embodiment of the present disclosure;

Figure 14A is a second schematic cross-sectional view taken along line A-A of Figure 10A;

Figure 14B is a schematic cross-sectional view three taken along line A-A of Figure 10A;

Figure 14C is a schematic cross-sectional view 4 taken along line A-A of Figure 10A;

Figure 14D is a schematic cross-sectional view 5 taken along line A-A of Figure 10A;

Figure 15 is a schematic plan view of a packaging sleeve according to an embodiment of the present disclosure;

Figure 16 is a perspective view of a packaging container according to an embodiment of the present disclosure;

Figure 17 shows the light transmittance at the indentation line of the packaging composite sheet according to the embodiment of the present disclosure, the light transmittance at the indentation line of the packaging composite sheet of Comparative Example 1, and the packaging composite sheet of Comparative Example 2. Comparison diagram of the transmittance at the indentation line of the composite sheet;

Figure 18 shows the oxygen permeability of the portion of the packaging composite sheet without indentation lines according to the embodiment of the present disclosure, the oxygen permeability of the portion of the packaging composite sheet without indentation lines of Comparative Example 1, and Schematic diagram of the comparison between the oxygen permeability of the portion of the packaging composite sheet without indentation lines in Comparative Example 2; and

Figure 19 is a schematic flowchart of a manufacturing method of a packaging composite sheet according to an embodiment of the present disclosure.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present disclosure.

Unless otherwise defined, technical or scientific terms used herein shall have their ordinary meaning understood by a person of ordinary skill in the art to which this disclosure belongs. "First", "second" and similar words used in the specification and claims of this patent application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprising" mean that the elements or things appearing before the word include the elements or things listed after the word and their equivalents, without excluding other elements or things. "Inside", "outside", "up", "down", "left", "right", etc. are only used to express relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. ground changes.

The drawings in this disclosure are not strictly drawn to actual scale, and the specific size and quantity of each structure can be determined according to actual needs. The drawings described in this disclosure are structural schematic diagrams only.

Packaging sheets are formed from multiple laminate layers in which the paper layer often acts as a carrier layer for other material layers, providing structural stability to the packaging container. The paper layer is a sheet-like composite layer made by depositing a suspension of animal or plant fibers that has been appropriately processed (for example, beaten) onto a forming device and dried. There are many parameters used to characterize the performance of paper layers, including but not limited to: weight, thickness, density, dustiness, color difference, porosity, tensile strength, breaking strength, folding strength, stiffness, roughness, smoothness strength, air permeability, water absorption, ink absorption, brightness, internal bonding strength, moisture content, etc.

The inventor of this application found through in-depth research that the leakage problem of packaging containers is mainly determined by the performance of the paper layer. Among the performance parameters of the above-mentioned paper layers, the bending strength is closely related to the leakage problem. When delamination occurs within the paper layer, the bending strength of the paper layer will be reduced, making leakage problems more likely to occur.

Figure 1 is a photo of the top appearance of a packaging container, and Figure 1A is a cross-sectional photo taken along line A-A of Figure 1 . The inventor found that in packaging containers with leakage at the top, the top sealing area usually has an uneven surface, and the blistering phenomenon shown in Figure 1 will appear from the appearance. The reason for the blistering phenomenon is that delamination occurs in the paper layer 11 and the paper layer 12 that are laminated to each other at the blistered location (as shown in FIG. 1A ). This delamination results in a reduction in the bending resistance of the paper layer 11 or 12, making it easier for packet leakage to occur at the sealing point.

Figure 2 is a photo of the appearance of the top ear flap of another packaging container. Figure 2A is a partial photo of the inner surface of the ear flap in Figure 2. Figure 2B is a partial enlarged photo of the inner surface of the ear flap in Figure 2A. After the inventor's research, when the bending resistance of the paper layer is low, it is more likely to leak at the ear flap, because the packaging sheet is folded more times at the ear flap, and the performance requirements for the paper layer are also higher. high. For example, it can be seen from Figure 2B that due to the low bending resistance of the paper layer, the packaging container cracks on the inner surface of its ear wing 13, This causes the ear wing 13 to leak.

In order to solve at least one of the above problems, embodiments of the present disclosure provide a paper layer of a packaging composite sheet. The paper layer includes in its thickness direction a first layer, a second layer arranged in a stack, and a layer located between the first layer and the second layer. The middle layer between the second layer. The first layer, the middle layer and the second layer each include wood chemical pulp, the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, The fiber length of the first fiber is greater than the fiber length of the second fiber. The content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer.

In the paper layer of the packaging composite sheet provided by the above embodiments of the present disclosure, by increasing the content of the first fiber chemical pulp in at least one of the second layer and the first layer, making it higher than the first fiber chemical pulp in the middle layer. pulp content, thereby improving the bending strength of the paper layer. On the one hand, it can improve the product quality of the packaging container. Even if the packaging sheet is folded multiple times, no package leakage will occur; on the other hand, it can make the packaging container have a flatter surface at the sealing point, thereby improving the packaging product quality. of aesthetics.

Figure 3 is a schematic plan view of a packaging composite sheet according to an embodiment of the present disclosure. FIG. 3A is a schematic cross-sectional view taken along line B-B of FIG. 3 . Figure 4 is a schematic structural diagram of a packaging sleeve according to an embodiment of the present disclosure. Figure 5 is a schematic structural diagram of a packaging container according to an embodiment of the present disclosure.

As shown in FIG. 3 , the packaging composite sheet 1 provided by the embodiment of the present disclosure includes a crease line pattern, and the crease line pattern includes a plurality of intersecting crease lines, such as crease lines 901 and 902 . After folding along multiple crease lines and bonding the left and right ends of the packaging composite sheet 1 to each other, a packaging sleeve as shown in Figure 4 can be formed. For the purpose of simplicity, only part of the crease lines are shown in FIG. 1 , and it can be understood that the embodiments of the present disclosure are not limited to the crease line pattern shown in FIG. 1 .

As shown in FIG. 4 , the packaging sleeve provided by the embodiment of the present disclosure has a sleeve-like structure, including a top opening 9A and a bottom opening 9B arranged oppositely. Before filling, one of the top opening 9A and the bottom opening 9B can be sealed, filling can be performed through the other opening, and then the other opening can be sealed to form a container with contents as shown in Figure 5 packaging container. In the embodiments of the present disclosure, the content may be food or industrial products, including but not limited to liquids, solids and mixtures thereof.

As shown in FIG. 3A , the packaging composite sheet 1 includes a paper layer 100 and a sealing layer 200 . The sealing layer 200 is stacked with the paper layer 100, so that when the top opening 9A and the bottom opening 9B of the packaging sleeve are sealed, the sealing layer 200 can be heated to play an adhesive role.

As shown in FIG. 3A , in the thickness direction D of the paper layer 100 , the paper layer 100 includes a stacked outer layer 10 (i.e., the first layer), an inner layer 30 (i.e., the second layer), and a layer located between the outer layer 10 and the inner layer. between 30 The middle layer 20. For example, the paper layer 100 includes a first side S1 and a second side S2 in the thickness direction D. The first side S1 is the side of the paper layer 100 facing the outside of the packaging container 9 , and the second side S2 is the side of the paper layer 100 facing outside. The side inside the packaging container 9 (that is, facing the content). The outer layer 10 is, for example, located on the first side S1 of the paper layer 100, and the inner layer 30 is, for example, located on the second side S2 of the paper layer 100. The middle layer 20 is sandwiched between the outer layer 10 and the inner layer 30 .

As shown in FIG. 3A , the packaging composite sheet 1 includes an outer surface 1A and an inner surface 1B that are opposite in the thickness direction D thereof. For example, the outer layer 10 of the paper layer 100 is disposed close to the outer surface 1A, and the inner layer 30 of the paper layer 100 is disposed close to the inner surface 1B.

In at least some embodiments, the sealing layer 200 may be located on at least one of the first side S1 and the second side S2 of the paper layer 100 . For example, as shown in FIG. 3A , in the thickness direction D of the paper layer 100 , the sealing layer 200 is located on the second side S2 of the paper layer 100 and is laminated with the inner layer 30 of the paper layer 100 . That is, in the thickness direction D, the sealing layer 200 and the middle layer 20 are respectively located on opposite sides of the inner layer 30 .

It can be understood that in other embodiments of the present disclosure, the sealing layer 200 may be located on the first side S1 of the paper layer 100, or may also be located on the first side S1 and the second side S2 of the paper layer 100. The present disclosure There is no limit to this.

FIG. 5A is a schematic cross-sectional view taken along line C-C of FIG. 5 . As shown in Figure 5, the packaging container 9 includes a top 91 and a bottom 92. The top 91 is obtained by sealing the top opening 9A, and the bottom 92 is obtained by sealing the bottom opening 9A. The crease line 901 defines the top perimeter of the packaging container 9 and the crease line 902 defines the bottom perimeter of the packaging container 9 .

As shown in FIG. 5A , when the top opening 9A is sealed, the packaging composite sheets 1 located on two opposite sides of the top opening 9A are bonded to each other, wherein the two sealing layers 200 are arranged to fit each other. , and then perform thermal activation or ultrasonic activation on the two sealing layers 200 to melt them, thereby achieving the sealing of the top opening 9A. The sealing method for the bottom opening 9B is the same as the above process and will not be repeated here.

In at least some embodiments, outer layer 10, middle layer 20, and inner layer 30 each include wood chemical pulp. That is, the outer layer 10, the middle layer 20 and the inner layer 30 have the same wood chemical pulp.

Generally, pulp can be divided into wood mechanical pulp, wood chemical pulp and wood chemical mechanical pulp, which are obtained through different process technologies. Wood mechanical pulp is produced by a mechanical pulping method. For example, the mechanical pulping method presses the wood segment from the length direction onto a moist, rough, uniformly rotating grindstone to separate the fibers from the wood segment, and then screens and concentrates it to make pulp. Wood mechanical pulp has the characteristics of low density, high bulk and low price. Wood chemical pulp is produced by chemical pulping methods, such as chemical pulping, which involves soaking wood chips in an appropriate In a chemical aqueous solution, it is cooked under high temperature and pressure to dissolve the lignin in the wood chips and obtain complete cellulose. Wood chemical pulp has the characteristics of low bulk and high cost. Wood chemical mechanical pulp is produced by a semi-chemical pulping method that combines chemical and mechanical methods. For example, in the semi-chemical pulping method, the wood chips are first partially softened or cooked with chemical substances, and then the gelatinization is completed using mechanical methods.

In at least some embodiments, the wood chemical pulp in the outer layer 10 , the middle layer 20 and the inner layer 30 includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the fibers of the first fibers The length is greater than the fiber length of the second fiber.

For example, the first fiber is a softwood fiber and the second fiber is a hardwood fiber. The fiber length of softwood fibers is greater than that of hardwood fibers. In one example, softwood fibers are 2.5 to 4 millimeters long and 41 to 55 microns wide, with an aspect ratio of less than 70, while hardwood fibers are about 1 millimeter long and shorter, equal to their length. 1/60th.

For example, softwoods include but are not limited to masson pine, larch, red pine, spruce, etc., and hardwoods include but are not limited to birch, poplar, basswood, eucalyptus, maple, etc. The tissue structure of softwood is tight, so the pulp quality is good and the lignin content is high. However, the polypentose content is low, and the fibers are not easy to absorb water and swell, making pulping difficult. The lignin content in the tissue structure of hardwood is lower than that of softwood, but the polypentose content is high, so it is easy to pulp.

In the embodiment of the present disclosure, by arranging the outer layer 10 , the middle layer 20 and the inner layer 30 to wood chemical pulp with two different fiber lengths, it not only reduces the difficulty of pulping, but also ensures good pulp quality and manufactures The paper layer is not easy to break.

For example, the first fibrous chemical pulp is sulfate coniferous chemical pulp, and the second fibrous chemical pulp is sulfate broadleaf chemical pulp.

The sulfate method and the sulfite method are two basic chemical pulping methods. The chemical pulp made by the sulfate method is called sulfate chemical pulp, and the pulp made by the sulfite method is called sulfite chemical pulp.

For example, kraft wood pulp uses a mixture of sodium hydroxide and sodium sulfide as the cooking agent. During the cooking process, because the action of the chemical liquid is relatively gentle, the fibers are not strongly eroded, so they are strong and strong. The paper produced has good folding resistance, burst resistance and tearing strength; generally it can be divided into bleached and unbleached Two kinds.

For example, sulfite wood pulp uses a mixture of sulfurous acid and acidic sulfite as a cooking agent. The fiber of this pulp is long, soft in nature, good in toughness, high in strength, easy to bleach, and has excellent interweaving ability; it can generally be divided into three types: unbleached, semi-bleached and bleached.

In the embodiment of the present disclosure, by setting the first fibrous chemical pulp in the outer layer 10, the middle layer 20 and the inner layer 30 as sulfate coniferous chemical pulp, and the second fibrous chemical pulp as sulfate broadleaf chemical pulp, The folding resistance and breakage resistance of each layer of the outer layer 10, the middle layer 20 and the inner layer 30 can be improved.

In one example, the kraft softwood chemical pulp is softwood bleached kraft chemical pulp, and the kraft broadleaf chemical pulp is broadleaf bleached kraft chemical pulp.

In at least some embodiments, at least one of the inner layer 30 and the outer layer 10 has a kraft softwood chemical pulp content that is higher than the middle layer 20 .

In this article, the "content" of a substance refers to the mass percentage or mass fraction (also called proportion or ratio) of the substance. For example, "the content of A in B is higher than the content of A in C" means Yes, the mass percentage of A in B is higher than the mass percentage of A in C.

For example, the content of the sulfate coniferous chemical pulp in the inner layer 30 is higher than the content of the sulfate coniferous chemical pulp in the middle layer 20 . In this way, the fiber ratio of the middle layer 20 remains unchanged by increasing the content of the inner layer 30 . The proportion of medium sulfate coniferous chemical pulp improves the bending strength of the inner layer 30 and prevents the inner layer 30 from cracking.

In one example, the mass percentage of the sulfate coniferous chemical pulp in the middle layer 20 in the middle layer 20 is 40% to 60%; the mass percentage of the sulfate coniferous chemical pulp in the inner layer 30 in the inner layer 30 is greater than Or equal to 70%, more preferably greater than or equal to 75%, further preferably greater than or equal to 85%, more preferably greater than or equal to 95%, and even more preferably 100%. If it is less than 70%, the folding resistance of the inner layer 30 will deteriorate, which may easily lead to rupture of the inner layer 30 and leakage of the package. Without considering cost, the larger the above numbers, the better.

For another example, the content of the sulfate softwood chemical pulp in the outer layer 10 is higher than the content of the sulfate softwood chemical pulp in the middle layer 20. In this way, the fiber ratio of the middle layer 20 remains unchanged by increasing the outer layer. The proportion of sulfate coniferous chemical pulp in 10 improves the bending strength of the outer layer 10 and prevents the outer layer 10 from cracking.

In one example, the mass percentage of the sulfate coniferous chemical pulp in the middle layer 20 in the middle layer 20 is 40% to 60%; the mass percentage of the sulfate coniferous chemical pulp in the outer layer 10 in the outer layer 10 is greater than or equal to 70%, more preferably greater than or equal to 75%, further preferably greater than or equal to 80%. If it is less than 70%, the folding resistance of the outer layer 10 will deteriorate, which may easily lead to rupture of the outer layer 10 and leakage of the package.

For another example, the contents of the sulfate coniferous chemical pulp in the inner layer 30 and the outer layer 10 are both higher than the content of the sulfate coniferous chemical pulp in the middle layer 20, so that the fiber ratio of the middle layer 20 remains unchanged. Next, by increasing the proportion of sulfate coniferous chemical pulp in the outer layer 10 and the inner layer 30, the bending strength of the outer layer 10 and the inner layer 30 is increased to avoid rupture of both the outer layer 10 and the inner layer 30.

In one example, the sulfate coniferous chemical pulp in the inner layer 30 accounts for the mass percentage of the inner layer 30 It is greater than or equal to 70%, more preferably greater than or equal to 75%, further preferably greater than or equal to 85%, more preferably greater than or equal to 95%, further preferably 100%; and the sulfate needles in the outer layer 10 The mass percentage of leaf chemical pulp in the outer layer 10 is greater than or equal to 70%, more preferably greater than or equal to 75%, further preferably greater than or equal to 80%.

In the embodiment of the present disclosure, the content of the sulfate needle chemical pulp in the inner layer 30 and the content of the sulfate needle chemical pulp in the outer layer 10 may be the same or different. That is, the mass percentage of the sulfate coniferous chemical pulp in the inner layer 30 in the inner layer 30 and the mass percentage of the sulfate coniferous chemical pulp in the outer layer 10 in the outer layer 10 may be the same or different. Those skilled in the art can comprehensively consider the manufacturing cost, various properties of the pulp and paper layer, etc. to make a selection.

In at least some embodiments, the content of the kraft softwood chemical pulp in the outer layer 10 is equal to the content of the kraft softwood chemical pulp in the inner layer 30 . That is, the mass percentage of the sulfate coniferous chemical pulp in the outer layer 10 in the outer layer 10 is equal to the mass percentage of the sulfate coniferous chemical pulp in the inner layer 30 in the inner layer 30 .

For example, the sulfate coniferous chemical pulp in the outer layer 10 accounts for 75% to 85% of the mass of the outer layer 10, and the sulfate coniferous chemical pulp in the inner layer 30 accounts for 75% to 75% of the mass of the inner layer 30. 85%; correspondingly, the sulfate broad-leaf chemical pulp in the outer layer 10 accounts for 15% to 25% of the mass of the outer layer 10, and the sulfate broad-leaf chemical pulp in the inner layer 30 accounts for the mass percentage of the inner layer 30 It is 15%~25%. By setting the content of the sulfate softwood chemical pulp in the outer layer 10 to be equal to the content of the sulfate softwood chemical pulp in the inner layer 30 , the paper layer 100 can be made smoother and less likely to warp or curl.

For another example, the sulfate coniferous chemical pulp in the outer layer 10 accounts for 80% to 85% of the mass of the outer layer 10, and the sulfate coniferous chemical pulp in the inner layer 30 accounts for 80% of the mass of the inner layer 30. ~85%; correspondingly, the sulfate broadleaf chemical pulp in the outer layer 10 accounts for 15% to 20% of the mass of the outer layer 10, and the sulfate broadleaf chemical pulp in the inner layer 30 accounts for the mass of the inner layer 30 The percentage is 15% to 20%. In this way, by increasing the proportion of sulfate coniferous chemical pulp in the outer layer 10 and the inner layer 30 , the bending strength of the outer layer 10 and the inner layer 30 can be further improved while ensuring the flatness of the paper layer 100 .

For another example, during the folding process of a packaging container, the external force used for folding will mainly be borne by the outer layer 10 or the inner layer 30. In order to ensure that no leakage occurs during the folding and forming process of the packaging container, it is necessary to ensure that the outer layer 10 and the inner layer The bending strength is 30. In one example, the sulfate coniferous chemical pulp in the outer layer 10 accounts for 100% of the mass of the outer layer 10 , and the sulfate coniferous chemical pulp in the inner layer 30 accounts for 100% of the mass of the inner layer 30 . The mass percentage is 100%. In this way, the leakage rate will be greatly reduced and customer complaints will be reduced. risks of.

In at least some embodiments, the outer layer 10 has a sulfate softwood chemical pulp content that is lower than the inner layer 30 . That is, the mass percentage of the sulfate coniferous chemical pulp in the outer layer 10 in the outer layer 10 is lower than the mass percentage of the sulfate coniferous chemical pulp in the inner layer 30 in the inner layer 30 .

For example, the sulfate coniferous chemical pulp in the outer layer 10 accounts for 75% to 85% of the mass of the outer layer 10, and the sulfate coniferous chemical pulp in the inner layer 30 accounts for 95% to 95% of the mass of the inner layer 30. 100%; correspondingly, the sulfate broad-leaf chemical pulp in the outer layer 10 accounts for 15% to 25% of the mass of the outer layer 10, and the sulfate broad-leaf chemical pulp in the inner layer 30 accounts for the mass percentage of the inner layer 30 It is 0~5%.

During the forming process of the packaging container 9, the inner layer 30 bears much greater force than the outer layer 10, so appropriately increasing the proportion of sulfate coniferous chemical pulp in the inner layer 30 will further prevent the inner layer 30 from cracking. In addition, considering the high cost of softwood chemical pulp, the above settings can also reduce the material cost of the paper layer as much as possible while ensuring the performance of the paper layer.

In at least some embodiments, the content of kraft broadleaf chemical pulp is less than the content of kraft softleaf chemical pulp in each of the outer layer 10 , the middle layer 20 and the inner layer 30 . That is, in each of the outer layer 10 , the middle layer 20 and the inner layer 30 , the mass percentage of sulfate broadleaf chemical pulp is lower than the mass percentage of sulfate needleleaf chemical pulp. Because the strength of soft-leaf chemical pulp is much better than that of broad-leaf chemical pulp, by increasing the proportion of soft-leaf chemical pulp, the bending strength of the paper layer 100 can be improved to avoid delamination and blistering.

Although softwood chemical pulp has high strength, its cost is also high. If all the softwood chemical pulp is used in the inner layer 30 and the outer layer 10, the cost of the paper will be greatly increased, and the thickness of the paper layer may also be reduced. . In the process of manufacturing packaging containers, in addition to considering the cost of materials and the performance of the selected materials, there are also requirements for the thickness of the packaging sheet 1 . In the field of packaging, thickness is usually characterized by gram weight. When selecting pulp fibers, not only the composition and proportion of the pulp must be considered, but also whether the gram weight of the final manufactured paper layer 100 can meet some specific requirements.

In the embodiment of the present disclosure, wood mechanical pulp or wood mechanochemical pulp can be added to the middle layer 20 . Because wood mechanical pulp and wood mechanochemical pulp have low cost and high bulk, by adding wood mechanical pulp or wood mechanochemical pulp to the middle layer 20 Wood mechanical chemical pulp can increase the weight of the paper layer while ensuring that the paper layer has good bending resistance to meet the weight requirements of packaging containers in different use environments.

It should be noted that in the embodiment of the present disclosure, only wood mechanical pulp or wood mechanochemical pulp is added to the middle layer 20, and there is no wood mechanical pulp or wood mechanochemical pulp in the outer layer 10 and the inner layer 30. That is, Yes, neither the outer layer 10 nor the inner layer 30 includes any wood mechanical pulp nor any wood mechanochemical pulp.

In at least some embodiments, the intermediate layer 20 includes wood mechanical pulp including a second fiber mechanical pulp having a second fiber. For example, the second fiber is hardwood fiber, and the second fiber mechanical pulp is hardwood mechanical pulp. Compared with soft-leaf mechanical pulp, broad-leaf mechanical pulp is preferred because it is cheaper.

For example, the mass percentage of broadleaf mechanical pulp in the middle layer 20 in the middle layer 20 is 40% to 50%, and more preferably 43% to 48%. If the proportion of mechanical pulp is too low, the bulk of the paper layer 100 will be insufficient, so the stiffness of the paper layer 100 will not meet the standard; if the proportion of mechanical pulp is too high, it will lead to an increase in paper powder, which is not conducive to food safety control.

In at least some embodiments, the grammage of at least one of the inner layer 30 and the outer layer 10 is 19% to 30% of the total grammage of the paper layer 100 . In the embodiment of the present disclosure, the total gram weight of the paper layer refers to the absolute dry gram weight of the paper layer, where the absolute dry value (gram weight) = paper gram weight * (1-moisture %), and moisture % refers to the proportion of moisture mass percentage, for example, about 7%.

For example, the total weight of the paper layer 100 is 195-205g/m ³ , the weight of the inner layer 30 is 37-62g/m ³ , and the weight of the outer layer 10 is 37-62g/m ³ .

In the embodiment of the present disclosure, the weight of the inner layer 30 and the weight of the outer layer 10 may be the same or different. Preferably, the gram weight of the inner layer 30 is smaller than the gram weight of the outer layer 10. In this way, the gram weight of the inner layer 30 can be reduced as much as possible while ensuring that the packaging material does not leak, and more intermediate layers can be used to maintain the gram weight. This will ensure more bulk and reduce the cost of the entire packaging material, making the entire packaging material more competitive.

For example, the gram weight of the inner layer 30 is 19% to 23% of the total gram weight of the paper layer 100 , and the gram weight of the outer layer 10 is 26% to 20% of the total gram weight of the paper layer 100 .

FIG. 6 is another schematic cross-sectional view taken along line B-B of FIG. 3 . Compared with FIG. 3A , the paper layer 100 of the packaging composite sheet 1 in FIG. 6 also includes a coating 40 . In the thickness direction D of the paper layer 100 , the coating layer 40 is stacked with the outer layer 10 and is located on the opposite side to the middle layer 20 . That is, the outer layer 10 is sandwiched between the coating 40 and the intermediate layer 20 , which are located on opposite sides of the outer layer 10 .

For example, the coating 40 is configured to have a printed pattern. By providing the coating 40 on the paper layer 100, the printing performance of the packaging container can be improved and the cost can be reduced.

For example, the coating 40 includes an inorganic non-metal material, such as china clay. As a pigment coating, china clay has the characteristics of high strength, good printing performance, and high gloss, so it is an excellent select.

For example, the pigment may also include calcium carbonate, typically precipitated calcium carbonate. In another example, coating 40 may also include latex, lubricants, thickeners, and the like. For example, the latex is preferably a 1:1 mixture of styrene-butadiene latex and styrene-acrylic latex. The styrene-butadiene latex can improve the coating strength, and the styrene-acrylic latex can reduce the coating odor.

As described previously, when the top opening or the bottom opening of the packaging sleeve is sealed, a thermal activation or ultrasonic activation process is used to melt the two sealing layers 200 in FIG. 5A . The area where the two sealing layers 200 are in direct contact is defined as a weld seam 200S.

The inventor found that in packaging containers with delamination, most of the thermal energy generated by ultrasonic waves is absorbed by the middle layer 20 in the paper layer 100, resulting in serious separation of the middle layer 20 from the outer layer 10 and the inner layer 30.

After the inventor's research, by increasing the thickness (ie, gram weight) of the coating 40, the weld seam 200S can absorb more heat. Since the heat absorbed by the intermediate layer 20 is reduced, the delamination phenomenon inside the paper layer 1 is also improved.

In at least some embodiments, the weight of the coating 40 is 6% to 9% of the total weight of the paper layer 100, preferably 6% to 7%. By setting the above weight range, most of the thermal energy generated by ultrasonic waves can be absorbed by the weld 200S during the activation process of the packaging container, thereby reducing the delamination phenomenon inside the paper layer 1 and thus helping to avoid package leakage. If the grammage of the coating 40 is too high, the strength of the entire paper layer will be reduced; if it is too low, it will have no effect.

In at least some embodiments, the thickness of coating 40 is 4% to 5% of the total thickness of paper layer 100 . For example, the thickness of the coating 40 is 13-15 microns, and the total thickness of the paper layer 100 is 280-300 microns.

An embodiment of the present disclosure also provides a method for manufacturing a paper layer of a packaging composite sheet. For example, this manufacturing method can be used to manufacture the paper layer of any of the packaging composite sheets of the previous embodiments.

Figure 7 is a method for manufacturing a paper layer of a packaging composite sheet according to an embodiment of the present disclosure, including forming a paper layer 100. For example, forming the paper layer 100 includes: forming an outer layer 10 (i.e., the first layer), an inner layer 30 (i.e., the second layer), and an intermediate layer 20 located between the outer layer 10 and the inner layer 30, wherein the outer layer 10, the middle layer Both the layer 20 and the inner layer 30 include wood chemical pulp, the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the first fibers having a fiber length greater than the fibers of the second fibers. Length; the content of the first fiber chemical pulp in at least one of the inner layer 30 and the outer layer 10 is higher than the content of the first fiber chemical pulp in the middle layer 20 .

In the manufacturing method of the paper layer of the packaging composite sheet provided by the above embodiments of the present disclosure, by providing The content of the first fiber chemical pulp in at least one of the inner layer and the outer layer is high, making it higher than the content of the first fiber chemical pulp in the middle layer, thereby improving the bending resistance strength of the paper layer. On the one hand, it can improve the product quality of the packaging container. Even if the packaging sheet is folded multiple times, no package leakage will occur; on the other hand, it can make the packaging container have a flatter surface at the sealing point, thereby improving the packaging product quality. of aesthetics.

For example, in the above manufacturing method, the steps of forming the outer layer 10, the inner layer 30 and the intermediate layer 20 between the outer layer 10 and the inner layer 30 include: providing wet pulp, adding starch and/or dry strength to the wet pulp agent; and applying the wet pulp to the forming device and drying.

For example, the delamination phenomenon of the paper layer 100 can be avoided by at least one of the following methods: Method 1: controlling the ratio between softwood pulp and broadleaf pulp in the wet pulp; Method 2: controlling the starch added to the wet pulp and/or the amount of dry strength. In the above manufacturing method, it can be controlled to add only dry strength agent to the wet pulp without adding starch to avoid delamination of the paper layer 100 .

Dry strength agent is a chemical used to enhance the bonding between fibers to improve the physical strength of paper (stiffness, tensile strength, ring crush strength, bursting strength, etc.) without affecting its wet strength. The application of dry strength agent can avoid problems such as increased paper tightness, increased wet deformation, decreased opacity, absorbency, air permeability and even tearing caused by increasing the beating degree. Dry strength agent is mainly amphoteric multi-component copolymer polyacrylamide, which can better combine with fibers and more effectively improve paper strength.

For example, the dosage of starch dry strength agent is 5-10kg/t, such as 5kg/t, 6kg/t, 7kg/t, 8kg/t, 9kg/t, 10kg/t.

Samples 1-3 below are examples of paper layers of the present disclosure. Table 1 shows the gram weight of each layer in Samples 1 to 3. Table 2 shows the fiber composition and ratio of the outer layer, middle layer and inner layer in Samples 1 to 2.

Table 1

Table 2

The fiber composition and ratio of each layer in the above samples 1 and 2 are obtained in the following ways:

1. Analysis method

Refer to GB/T 4688-2020 Analysis of paper, cardboard and pulp-fiber composition to analyze the fiber composition and ratio of the sample.

Principle: Fiber composition analysis is to take a small amount of representative fibers from the sample to be tested, dye it, and then observe it with a microscope. Qualitative analysis was performed based on the dyeing reaction of the fiber and the morphological characteristics of the fiber. The number of intersection points between various fibers and the counting line is measured and counted, and the quality factor is used to convert the number of intersection points into mass fractions for quantitative analysis.

2. Sample preparation

Cut five specimens of approximately 50mm x 50mm from different parts of the sample and soak them in hot water of approximately 70°C until the layers are completely separated. If the separation layer contains fibers from adjacent layers, these must be carefully removed during the separation process. Take an appropriate amount of each layer of sample and put it into a test tube, add water to a concentration of about 0.1%, and disperse it to make a fiber suspension for observation of fiber morphology.

3. Dyeing and Filmmaking

1. Dyeing

Herzberg stain and Selleger stain were selected for analysis.

Herzberg dye can be used to qualitatively and quantitatively distinguish chemical pulp, mechanical pulp and cotton and linen pulp. It can also be used to qualitatively identify semi-chemical pulp and distinguish viscose fiber and synthetic fiber. Color reaction of Herzberg stain:

A. Chemical pulp fiber (softwood, hardwood, reed, bagasse, straw, wheat straw, sorghum straw, asparagus): blue-purple.

B. Mechanical pulp fiber: bright yellow.

C. Cotton fiber: wine red, bast fiber (flax hemp): dark wine red.

In addition to the above main color differences, Herzberg dyeing can be based on the sulfite softwood pulp. The presence of sulfite softwood pulp can be determined by the yellow color of wood ray cells due to the presence of resin.

Selleger stain is mostly used to identify softwood pulp and hardwood pulp. It can also be used to distinguish between wood pulp and straw pulp. Color reaction of Selleger stain:

A. Bleached acid softwood pulp: transparent light rose color.

B. Bleached alkali process softwood pulp: light dark brown red.

C. Hardwood pulp: blue-purple.

D. Groundwood pulp: dark yellow.

E. Cotton and linen pulp: wine red to reddish brown.

2. Production

Take an appropriate amount of fiber suspension and dilute it with water to a concentration of about 0.05% (mass fraction). Use a dropper to drop 1.0mL of the suspension onto a clean, grease-free microscope slide. Use a dissecting needle to disperse the fibers evenly and dry on a heating plate. Slides are cooled and stained with the corresponding stain. After staining 1 cover for 1 to 2 minutes, cover it with a microscope cover slip. Try to avoid air bubbles between the slide and the cover slip. Tilt the slide and use filter paper to absorb the excess stain. The test piece That is, available for observation and analysis.

4. Sample observation and analysis

1. Qualitative analysis

Place the test piece on the stage of the microscope, move the test piece regularly in the horizontal or vertical direction, and observe the entire test piece. According to the fiber morphological characteristics and dyeing conditions, the fiber type and pulping method are identified. Observe at least 2 test pieces for each sample.

2. Quantitative analysis

This analysis uses a microscope to distinguish fiber types based on different types of fiber staining and fiber morphological characteristics. Statistics were performed using the radical method.

Place the test piece on the stage of the microscope, and move the test piece with the help of the stage so that the center point of the field of view falls 3 mm to 5 mm above the cover glass from the edge. Then move the test piece regularly in the horizontal or vertical direction to count the number of various fibers. After counting the number of fibers on one observation line, move the test piece parallel about 5mm to another observation line and record in the same way. Every fiber in every thread. During the continuous counting process, you should not return to the original row position and count again. In the statistical process, fiber fragments smaller than 0.1mm are ignored, but those fiber fragments with larger longitudinal splits should be counted, and each fiber in the fiber bundle is counted. Two or more test pieces should be measured to ensure that the number of fibers counted is more than 600. After the measurement is completed, calculate the mass fraction of each component according to the following formula.

Among them, Wi is the mass fraction (%); fi is the quality factor; Ni is the total number of fibers of each type; k is the number of fiber components. Table 3 shows the allowable errors in fiber ratio measurement. The calculation results are accurate to whole numbers. If the mass fraction is less than 2%, it is recorded as "trace amount".

table 3

Allowable error in fiber ratio measurement GB/T4688-1984

Through experiments, it was found that none of the above-mentioned samples 1 to 3 had any leakage at the top, bottom or ear wings, and the surfaces of the top and bottom were also relatively flat.

Figure 7 is a photo of the top appearance of the packaging container according to the embodiment of the present disclosure. 8 is a cross-sectional photograph of the top seal of the packaging container according to the embodiment of the present disclosure. Figures 7 and 8 represent the test results of Sample 1.

It can be seen from Figure 7 that the top surface of the packaging container made of the packaging composite sheet of Sample 1 is relatively flat, and no blistering occurs. As can be seen from Figure 8, there is no delamination phenomenon in sample 1, and the leak-proof bag effect is better. This is mainly because the proportion of sulfate coniferous chemical pulp in the inner layer of sample 1 is high (up to 99%).

Figure 9 is a cross-sectional photograph of the top seal of a packaging container according to another embodiment of the present disclosure. Figure 9 represents the test results of Sample 2. As can be seen from Figure 9, there is no delamination phenomenon in sample 2. Compared with Figure 8, the activation temperature and pressure used in Figure 9 are higher, causing the weld seam to be burned. However, even in this case, no delamination occurred in sample 2.

In the paper layer of the packaging composite sheet and its manufacturing method, the packaging composite sheet and the packaging container provided by the above embodiments of the present disclosure, by increasing the content of the first fiber chemical pulp in at least one of the inner layer and the outer layer, Make it higher than the content of the first fiber chemical pulp in the middle layer, thereby improving the bending resistance strength of the paper layer. On the one hand, it can avoid delamination at the top and bottom seals, thereby avoiding package leakage at the top, bottom or ear wings, and improving the product quality of the packaging container; on the other hand, it can make the formed packaging container The top and bottom of the packaging have a relatively flat surface at the sealing point, which improves the aesthetics of the packaged product.

Embodiments of the present disclosure also provide a packaging composite sheet, a packaging sleeve, a packaging container, and a manufacturing method of the packaging composite sheet. The composite sheet for packaging includes a paper layer and a sealing layer. The sealing layer It is arranged on the first side of the paper layer in the thickness direction of the packaging composite sheet, and the internal bonding strength of the paper layer is 190-230J/m2. It can not only solve the problems of easy tearing, easy delamination and substandard dustiness of composite sheets, but also solve the problems of bursting and increased oxygen permeability of packaging containers made of composite sheets.

At present, commodity trade exchanges between countries and regions are very frequent. In order to facilitate storage, transportation and sale, commodities usually need to be packaged. For example, many foods need to be sealed and placed in various forms of packaging containers such as packaging boxes and bags. For example, packaging containers used to package goods are formed by cutting, folding and sealing sheet-shaped composite sheets. Therefore, the quality of the composite sheets directly determines the performance of the packaging container.

In addition to glass bottles and metal cans, a packaging container currently widely used is formed by cutting, folding and sealing sheet-shaped composite sheets, which include multiple layers stacked on top of each other. , and the quality of the composite sheet directly determines the performance of the packaging container. Although this type of packaging container has been developed for decades and has made great progress, there are still various problems, such as: the composite sheet is easy to tear, the multiple layers included in the composite sheet Easy to delaminate, the dustiness of composite sheets does not meet the requirements for use (for example, the dustness of composite sheets used for food packaging does not meet food hygiene requirements), packaging containers made of composite sheets are in the folded position Packaging containers made of composite sheets are easy to burst and have high oxygen permeability (for example, high oxygen permeability will cause the food contained in the packaging container to deteriorate), etc.

In response to this series of problems, the inventor of the present application has conducted extensive and in-depth research on composite sheets. The main body of the composite sheet is usually a paper layer, which is the carrier layer for other film layers of the composite sheet and gives structural stability to the composite sheet and packaging containers made of the composite sheet. The paper layer is a sheet or plate made by drying appropriately processed (for example, beating) plant fibers, mineral fibers, animal fibers, chemical fibers, or mixtures of these fibers from a suspension onto an appropriate forming device. shape structure. The produced paper layer can be characterized by the following performance parameters: (1) General performance parameters, such as weight, thickness, density, etc.; (2) Appearance performance parameters, such as dustiness, color difference, porosity, etc.; (3) Strength performance parameters, such as tensile strength, breaking length, folding endurance, etc.; (4) Bending performance parameters, such as stiffness, crush strength, flat compression strength, etc.; (5) Surface performance parameters, such as roughness , smoothness, printing surface strength, etc.; (6) Absorption performance parameters, such as air permeability, water absorption, ink absorbency, etc.; (7) Optical properties, such as brightness, etc.; (8) Other performance parameters, such as inner Bonding strength, moisture content, sizing degree, etc. Among so many complicated performance factors, the inventor of the present application found that the internal bond strength (IB) of the paper layer is A key factor in solving some of the current problems with composite sheets and packaging containers made of composite sheets.

FIG. 10A is a first schematic plan view of a packaging composite sheet according to an embodiment of the present disclosure; FIG. 10B is a first schematic cross-sectional view taken along line AA in FIG. 10A . Referring to Figures 10A and 10B, an embodiment of the present disclosure provides a packaging composite sheet. The packaging composite sheet includes a paper layer 1 and a sealing layer 2. The sealing layer 2 is in the thickness direction of the packaging composite sheet. is arranged on the first side of the paper layer 1, and the internal bonding strength of the paper layer 1 is 190-230J/m ² .

When the inside or between layers of paper is subjected to pressure or impact, it will cause structural failure such as surface fluffing, blistering or delamination between layers. Internal bonding strength is a representation of the ability of the paper layer to resist the above-mentioned structural effects. Its size depends on the bonding strength between fibers within the layer and the bonding strength between fibers in each layer. The internal bonding strength can be measured using the standard measurement methods stipulated in national standards, for example, see the national standard GB/T26203-2010.

If the internal bonding strength of the paper layer 1 is less than the above range, tearing problems will easily occur when using composite sheets to make packaging containers. When filling food in containers), the multiple layers included in the composite sheet are easy to delaminate, and the dustiness of the composite sheet does not meet the requirements for use (for example, food hygiene requirements are not met); if the internal bonding of paper layer 1 If the strength is greater than the above range, the packaging container made of the composite sheet will easily burst at the folded position (this position corresponds to the indentation line of the composite sheet), resulting in leakage of the package, and the packaging container made of the composite sheet will have irregularities. The oxygen permeability at the folded position (this position corresponds to the portion of the composite sheet that does not have an indentation line) increases, thereby easily causing the contents contained in the packaging container to deteriorate. According to embodiments of the present disclosure, the internal bonding strength of the paper layer 1 of the composite sheet for packaging is 190-230J/m ² , which can not only solve the problems of easy tearing, easy delamination and substandard dustiness of the composite sheet, but also solve the problem. It can solve the problems of packaging containers made of composite sheets bursting and oxygen permeability increasing.

For example, the material of the sealing layer 2 is a heat-activatable high-molecular polymer or an ultrasonic-activatable high-molecular polymer. By heating or applying ultrasonic vibration, the sealing layer 2 can be partially melted and bonded together, thereby sealing the composite sheet into a packaging container. For example, the material of the sealing layer 2 includes metallocene polyethylene.

Composite sheet is the blank used to make packaging containers. As an example, Figure 10A shows a schematic plan view of a composite sheet used to make a packaging container. Referring to FIG. 10A , the composite sheet has first and second sides S10 and S20 opposite each other and third and fourth sides S30 and S40 opposite each other. The composite sheet is configured by folding the composite sheet and connecting the third side S30 And the fourth side S40 gets packaged Sleeve (see Figure 15 to be described below). For example, the fourth side S40 of the composite sheet has a sealing strip SS, the composite sheet is folded so that the third side S30 and the fourth side S40 overlap at the sealing strip SS, and the third side S30 and the fourth side are separated by the sealing strip SS. S40 are connected to each other to form a packaging sleeve. The position between the two dotted lines in Figure 15 corresponds to the sealing strip SS in Figure 10A.

Continuing to refer to Figure 10A, the composite sheet has an indentation line, indicated by a dotted line; the indentation line is formed by pressing the composite sheet; the position of the indentation line is when the composite sheet is subsequently used to form a packaging sleeve and packaging container. The folding position and the formation of the indentation line will make the subsequent folding process easier and make it easier for the final packaging container to achieve the desired shape.

It should be noted that in the embodiment of the present disclosure, a square package with a regular packaging container is used as an example to describe, and accordingly the indentation line is also an indentation line used to form a square package. However, the embodiments of the present disclosure are not limited thereto. The composite sheet according to the embodiments of the present disclosure can be used to form a packaging container of any desired shape. Correspondingly, the position of the indentation line can also be appropriately and flexibly designed according to the shape of the packaging container. .

It should be noted that the composite sheets are shown in the drawings to have indentation lines; however, the embodiments of the present disclosure are not limited thereto, and the packaging composite sheets according to the embodiments of the present disclosure may not have indentation lines. .

Figure 11 is a second schematic plan view of a composite sheet for packaging according to an embodiment of the present disclosure; Figure 12 is a schematic plan view three of a composite sheet for packaging according to an embodiment of the present disclosure; Figure 13 is a schematic plan view of a composite sheet for packaging according to an embodiment of the present disclosure. Schematic diagram of the sheet 4. Figure 10A shows a composite sheet used to make a packaging container, which can be called a composite sheet unit U; the composite sheets shown in Figures 11 to 13 respectively include a plurality of composite sheet units shown in Figure 10A U. In FIG. 11 , the composite sheet includes a plurality of composite sheet units U connected together, and the plurality of composite sheet units U are respectively arranged along a first direction and a second direction intersecting the first direction. In FIG. 12 , the composite sheet includes a plurality of composite sheet units U connected together, and the plurality of composite sheet units U are arranged only in the first direction. In FIG. 13 , the composite sheet includes a plurality of composite sheet units U connected together, and the plurality of composite sheet units U are arranged only in the second direction. For example, the first direction is parallel to the sealing strip SS as described above. For example, the second direction is perpendicular to the first direction. The composite sheet according to the embodiment of the present disclosure can be presented in the form shown in Figure 10A, or can also be presented in the form shown in Figure 11 or Figure 12 or Figure 13, which is not limited by the embodiment of the present disclosure.

It should be noted that in the plan views of FIG. 10A and FIGS. 11 to 13 , the composite sheets according to the embodiments of the present disclosure are in a flat state; however, the embodiments of the present disclosure are not limited thereto. According to the embodiments of the present disclosure, The composite sheet can also be wound on a reel in a curled state.

As mentioned above, the paper layer is made by precipitating appropriately processed (for example, beating) plant fibers, mineral fibers, animal fibers, chemical fibers or mixtures of these fibers from a suspension onto an appropriate forming device and drying them. Flake or plate-like structure. This type of suspension containing appropriately treated (for example, beaten) plant fibers, mineral fibers, animal fibers, chemical fibers or mixtures of these fibers may be called wet pulp. There are two sources of wet pulp: one is to directly process the raw materials into wet pulp in the raw material origin (for example, wood origin), and then directly use the wet pulp to make paper; the other is to process the raw material directly into wet pulp in the raw material origin (for example, wood origin) The raw materials are processed into preliminary wet pulp and the preliminary wet pulp is dried and formed into dry pulp. The dry pulp is then transported to a papermaking factory, where the dry pulp is broken up and diluted with a solution to obtain wet pulp for papermaking. In comprehensive comparison, the second method is more flexible and lower cost. In the second method, during the process of breaking up and diluting the dry pulp, the shape, length and bonding between fibers will be changed, thereby affecting the internal bonding strength of the formed paper layer. According to embodiments of the present disclosure, when the raw material of the paper layer is dry pulp (that is, in the second method mentioned above), in order to solve the problems that the composite sheet is easy to tear, easy to delaminate, and the dust level is not up to standard, and To solve the problems of packaging containers made of composite sheets bursting and oxygen permeability increasing, the internal bonding strength of paper layer 1 is 210-230J/m ² . That is, according to embodiments of the present disclosure, when the internal bonding strength of the paper layer 1 is 210-230 J/m ² , the above series of problems can be solved on the premise of using a highly flexible and low-cost papermaking process.

For example, according to an embodiment of the present disclosure, the density of paper layer 1 is 700-760kg/m ³ . The density of paper layer 1 refers to the mass of paper layer per unit volume, which can reflect the tightness of fiber combination in paper layer 1. When the internal bonding strength of paper layer 1 is 210-230J/m ² , by making the density of paper layer 1 700-760kg/m ³ , it can better solve the problem that the composite sheet is easy to tear, easy to delaminate, and It solves the problem of substandard dust levels and solves the problems of packaging containers made of composite sheets bursting and oxygen permeability increasing. Preferably, the density of paper layer 1 is 720-750kg/m ³ .

For example, according to an embodiment of the present disclosure, the thickness of paper layer 1 is 275-295 μm. When the internal bonding strength of paper layer 1 is 210-230J/ ^m2 , by making the thickness of paper layer 1 275-295μm, it can better solve the problem that the composite sheet is easy to tear, easy to delaminate and the dust is not high. Meet the standards and solve the problems of packaging containers made of composite sheets bursting and oxygen permeability increasing. Preferably, the thickness of paper layer 1 is 280-290 μm.

For example, according to an embodiment of the present disclosure, the grammage of the paper layer 1 is 205-218g/m ² . The gram weight of the paper layer is also called the basis weight, which refers to the mass of the paper layer per unit area and can reflect the weight of the paper layer. In the case where the internal bonding strength of paper layer 1 is 210-230J/ ^m2 , by making the weight of paper layer 1 be 205-218g/ ^m2 , It can better solve the problems of easy tearing, easy delamination and substandard dustiness of composite sheets, and solve the problems of bursting of packaging containers made of composite sheets and increased oxygen permeability.

For example, according to embodiments of the present disclosure, the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.3-0.8cm ³ /(m ² ·24h ·0.1MPA); in this case, it can be effectively To effectively prevent the contents contained in packaging containers made of composite sheets from deteriorating. The oxygen permeability can be measured using the standard measurement methods stipulated in national standards, for example, see the national standard GB/T 18192-2008. Preferably, the oxygen permeability of the portion of the packaging composite sheet without indentation lines according to the embodiment of the present disclosure is 0.5-0.6cm ³ /(m ² ·24h ·0.1MPA) to more effectively prevent containment Contents in packaging containers made of composite sheets deteriorate and deteriorate.

Figure 17 shows the light transmittance at the indentation line of the packaging composite sheet according to the embodiment of the present disclosure, the light transmittance at the indentation line of the packaging composite sheet of Comparative Example 1, and the packaging composite sheet of Comparative Example 2. Schematic diagram of the comparison between the three transmittances at the indentation line of the composite sheet. In Comparative Example 1, the internal bonding strength of the paper layer of the composite sheet sample is less than 190-230 J/m ² according to the embodiment of the present disclosure; in Comparative Example 2, the internal bonding strength of the paper layer of the composite sheet sample is greater than that according to the embodiment of the present disclosure. 190-230J/m ² for embodiments of the present disclosure. It can be seen from the comparative schematic diagram of FIG. 17 that the transmittance of the packaging composite sheet according to the embodiment of the present disclosure is low at the indentation line, so that the packaging container made of the composite sheet according to the embodiment of the present disclosure will be damaged. Less likely to burst. 18 is the oxygen permeability of the portion of the packaging composite sheet without indentation lines according to the embodiment of the present disclosure, the oxygen permeability of the portion of the packaging composite sheet without indentation lines of Comparative Example 1, and Schematic diagram of the comparison between the oxygen permeability of the portion of the packaging composite sheet without indentation lines in Comparative Example 2. In Comparative Example 1, the oxygen permeability of the parts without indentation lines of two composite sheet samples SP1 and SP2 was collected. The internal bonding strength of the paper layers of the two composite sheet samples SP1 and SP2 was smaller than that according to the present invention. 190-230J/m ² in the disclosed embodiment; in Comparative Example 2, the oxygen permeability of the parts without indentation lines of two composite sheet samples SP3 and SP4 were collected. The two composite sheet samples SP3, SP4 were collected. The internal bonding strength of the paper layer of SP4 is greater than 190-230J/m ² according to the embodiment of the present disclosure; in the embodiment of the present disclosure, the transparency of the parts without indentation lines of the two composite sheet samples SP5 and SP6 was collected. oxygen rate. It can be clearly seen from FIG. 18 that the oxygen permeability of the portion of the packaging composite sheet without the indentation line is 0.3-0.8cm ³ /(m ² ·24h ·0.1MPA), and More specifically, it is 0.5-0.6cm ³ /(m ² ·24h·0.1MPA), which is a low oxygen permeability level. Therefore, the internal bonding strength of the paper layer 1 of the packaging composite sheet according to the embodiment of the present disclosure is 190-230 J/m ² , which solves the problems that the composite sheet is easy to tear, easy to delaminate, and the dust level is not up to standard, and The problem of bursting of packaging containers made of composite sheets is solved; at the same time, the oxygen permeability of the packaging composite sheets according to the embodiments of the present disclosure is It has excellent indicators and can effectively prevent the contents contained in the packaging container from deteriorating.

For example, according to an embodiment of the present disclosure, the dust level of the packaging composite sheet is: the dust level of the packaging composite sheet used to form 1000 packaging containers is less than 10 g. That is, the total dust level of 1000 composite sheet units U shown in FIG. 10A is less than 10 g. This further illustrates that for the packaging composite sheet according to the embodiment of the present disclosure, the dust level is very low in the case where the internal bonding strength of the paper layer 1 is 190-230 J/ ^m2 .

FIG. 14A is a second schematic cross-sectional view taken along line A-A in FIG. 1 . Referring to FIG. 14A , in the packaging composite sheet according to the embodiment of the present disclosure, the paper layer 1 is composed of three fiber layers 11 , 12 and 13 . That is, the paper layer 1 only includes three fiber layers 11, 12 and 13. During the papermaking process, each time wet pulp is applied to the forming device, a fiber layer is formed. Therefore, corresponding to the paper layer 1 according to the embodiment of the present disclosure, wet pulp is applied to the forming device three times in total during the papermaking process, the process is simple, and the process is easier to control. In Figure 14A, for the convenience of drawing, the interfaces between the three fiber layers 11, 12 and 13 are regular and smooth interfaces; in fact, the interfaces between the three fiber layers 11, 12 and 13 are uneven. Rules interface.

Figure 14B is a schematic cross-sectional view three taken along line A-A of Figure 1; Figure 14C is a schematic cross-sectional view four taken along line A-A of Figure 1; Figure 14D is a schematic cross-sectional view five taken along line A-A of Figure 1. The packaging composite sheet according to the embodiment of the present disclosure further includes a barrier layer 3 , which is disposed on the first side of the paper layer 1 and located between the paper layer 1 and the sealing layer 2 in the thickness direction of the packaging composite sheet. 14B; or, in the thickness direction of the packaging composite sheet, the barrier layer 3 is disposed on the second side of the paper layer 1 opposite to the first side, see FIG. 14C; or, in the packaging composite sheet In the thickness direction of the material, the barrier layer 3 is both disposed on the first side of the paper layer 1 and between the paper layer 1 and the sealing layer 2, and is also disposed on the second side of the paper layer 1 opposite to the first side, see Figure 14D. For example, the barrier layer 3 blocks liquid, prevents liquid from penetrating into the paper layer 1 or even flowing out, and prevents moisture from penetrating from the outside. For example, the barrier layer 3 also has gas-blocking and light-blocking properties. For example, the material of the barrier layer 3 is selected from at least one of high molecular polymers, metal oxides, non-metal oxides and metals. For example, the high molecular polymer is at least one of low density polyethylene, medium density polyethylene and high density polyethylene. An example of a metal oxide is aluminum oxide. An example of a non-metal oxide is silicon oxide. For example, the metal is aluminum.

According to an embodiment of the present disclosure, a packaging sleeve is further provided, including the packaging composite sheet according to the embodiment of the present disclosure as described above. For example, a packaging sleeve according to an embodiment of the present disclosure is made of a composite sheet according to an embodiment of the present disclosure. Figure 15 is a schematic plan view of a packaging sleeve according to an embodiment of the present disclosure. The third side S30 and the fourth side S40 of the packaging composite sheet according to the embodiment of the present disclosure are The sealing strips SS are connected to each other to form the packaging sleeve shown in Figure 15. The packaging sleeve has an upper end TP and a lower end BP that are open and opposite each other, and is configured to obtain a packaging container by folding and sealing the upper end TP and the lower end BP of the packaging sleeve (see Figure 16 to be described below). In the packaging sleeve, the upper end TP and the lower end BP are open, and other parts except the upper end TP and the lower end BP do not have open openings. Figure 15 shows a packaging sleeve for making a single packaging container. For example, multiple packaging sleeves may be connected together along a first direction and transported to the packaging container production line in a flat or curled state. The packaging sleeve according to the embodiment of the present disclosure has the same technical effect as the packaging composite sheet according to the embodiment of the present disclosure, which will not be described again here.

According to an embodiment of the present disclosure, a packaging container is also provided, including the packaging composite sheet as described above implemented according to the present disclosure. For example, a packaging container according to an embodiment of the present disclosure is made of a composite sheet according to an embodiment of the present disclosure. Figure 16 is a perspective view of a packaging container according to an embodiment of the present disclosure. For example, the upper end TP and the lower end BP of the packaging sleeve are folded and sealed to obtain the packaging container shown in Figure 16; for example, contents such as food are put in before sealing, and the contents are sealed in the package while forming the packaging container through sealing. in the container. For example, the upper end TP and the lower end BP of the packaging sleeve are sealed by thermal activation or ultrasonic activation of the sealing layer 2 . It should be noted that FIG. 16 shows a regular square package as an example of the packaging container of the embodiment of the present disclosure; however, the embodiment of the present disclosure is not limited thereto, and the packaging container according to the embodiment of the present disclosure may have any desired shape. The packaging container according to the embodiment of the present disclosure has the same technical effect as the packaging composite sheet according to the embodiment of the present disclosure, which will not be described again here.

According to an embodiment of the present disclosure, a method for manufacturing a composite sheet for packaging is also provided. Figure 19 is a schematic flowchart of a manufacturing method of a packaging composite sheet according to an embodiment of the present disclosure. Referring to Figure 19, the manufacturing method of the composite sheet for packaging includes: forming a paper layer, including: providing wet pulp; and applying the wet pulp to the forming device and drying to form the paper layer; and forming a sealing layer, in the composite sheet for packaging The sealing layer is formed on the first side of the paper layer in the thickness direction of the sheet, wherein forming the paper layer further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230 J/m ² . If the internal bonding strength of the paper layer 1 is less than the above range, tearing problems will easily occur when using composite sheets to make packaging containers. When filling food in containers), the multiple layers included in the composite sheet are easy to delaminate, and the dustiness of the composite sheet does not meet the requirements for use (for example, food hygiene requirements are not met); if the internal bonding of paper layer 1 The strength is greater than the above range, and the packaging container made of composite sheet is prone to bursting at the folded position (this position corresponds to the indentation line of the composite sheet), resulting in package leakage, and the packaging container made of composite sheet The oxygen permeability at the unfolded position of the packaging container (this position corresponds to the portion of the composite sheet that does not have an indentation line) increases, which can easily lead to the deterioration of the contents contained in the packaging container. The internal bonding strength of the paper layer 1 of the packaging composite sheet produced according to the manufacturing method of the embodiment of the present disclosure is 190-230J/m ² , which can solve the problem that the composite sheet is easy to tear, easy to delaminate, and the dust level is not up to standard. It can also solve the problems of packaging containers made of composite sheets bursting and the oxygen permeability increasing.

For example, a manufacturing method according to an embodiment of the present disclosure further includes: providing wet pulp includes: providing dry pulp, breaking up the dry pulp and diluting it with a solution to obtain wet pulp; and the manufacturing method further includes: controlling the internal bonding strength of the paper layer to The internal bonding strength of the paper layer is 210-230J/m ² . In this way, the manufacturing method according to the embodiment of the present disclosure can solve the above series of problems on the premise of using a highly flexible and low-cost papermaking process.

For example, in the manufacturing method according to the embodiment of the present disclosure, the internal bonding strength of the paper layer is controlled by at least one of the following ways: Way 1: Control the beating degree of the wet pulp; Way 2: Control the needles in the wet pulp The ratio between pulp and broadleaf pulp; Method 3: Control the amount of starch and/or dry strength agent added to the wet pulp; and Method 4: Control the amount of starch and/or dry strength applied between the fiber layers of the paper layer amount of dose. For example, in Mode 1, the higher the beating degree, the greater the internal bonding strength of the paper layer; conversely, the lower the beating degree, the smaller the internal bonding strength of the paper layer. For example, in Mode 2, coniferous pulp uses coniferous plants as the main raw material, and broadleaf pulp uses broadleaf plants as the main raw material; when preparing the fiber layer 13 in the middle of the paper layer 1, more coniferous pulp is used. It helps to increase the internal bonding strength of the paper layer; using more broadleaf pulp when preparing the middle fiber layer 13 of the paper layer 1 helps to reduce the internal bonding strength of the paper layer. For example, in mode 3, the dry strength agent is polyvinyl amide. Increasing the amount of starch and/or dry strength agent added to the wet pulp will help improve the internal bonding strength of the paper layer; conversely, reducing the amount of starch and/or dry strength agent added to the wet pulp / or the amount of dry strength agent helps reduce the internal bonding strength of the paper layer. For example, in Mode 4, the dry strength agent is polyvinyl amide, and increasing the amount of starch and/or dry strength agent applied between the fiber layers of the paper layer will help improve the internal bonding strength of the paper layer; conversely, Reducing the amount of starch and/or dry strength agent applied between the fiber layers of the paper layer helps reduce the internal bond strength of the paper layer. The manufacturing method of the packaging composite sheet according to the embodiment of the present disclosure has the same technical effect as the packaging composite sheet according to the embodiment of the present disclosure, and will not be described again here.

In addition, the present disclosure may also include the following embodiments or examples.

(1) A paper layer of a packaging composite sheet, the paper layer including, in its thickness direction, a first layer, a second layer, and an intermediate layer located between the first layer and the second layer. layer, wherein the first layer, the middle layer and the second layer each include wood chemical pulp, the wood chemical pulp Comprising a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the fiber length of the first fibers being greater than the fiber length of the second fibers;

Wherein, the content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer.

(2) The paper layer of the packaging composite sheet according to (1), wherein:

The first fiber is softwood fiber, and the first fiber chemical pulp is sulfate softwood chemical pulp;

The content of the sulfate softwood chemical pulp in at least one of the second layer and the first layer is higher than the content of the sulfate softwood chemical pulp in the middle layer.

(3) The paper layer of the packaging composite sheet according to (2), wherein:

The content of the sulfate softwood chemical pulp in the second layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and

The mass percentage of the sulfate needle chemical pulp in the second layer of the second layer is greater than or equal to 70%.

(4) The paper layer of the packaging composite sheet according to (3), wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is greater than or equal to 85%.

(5) The paper layer of the packaging composite sheet according to (4), wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is 100%.

(6) The paper layer of the packaging composite sheet according to (2), wherein:

The content of the sulfate softwood chemical pulp in the first layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and

The mass percentage of the sulfate needle chemical pulp in the first layer of the first layer is greater than or equal to 70%.

(7) The paper layer of the packaging composite sheet according to (6), wherein:

The content of the sulfate softwood chemical pulp in the first layer is equal to the content of the sulfate softwood chemical pulp in the second layer.

(8) The paper layer of the packaging composite sheet according to (7), wherein:

The mass percentage of the sulfate needle chemical pulp in the first layer of the first layer is 75% to 85%;

The sulfate needle chemical pulp in the second layer accounts for 75% to 85% of the mass of the second layer.

(9) The paper layer of the packaging composite sheet according to (6), wherein:

The content of the sulfate softwood chemical pulp in the first layer is lower than the content of the sulfate softwood chemical pulp in the second layer.

(10) The paper layer of the packaging composite sheet according to (9), wherein:

The sulfate needle chemical pulp in the second layer accounts for 95% to 100% of the mass of the second layer.

(11) The paper layer of the packaging composite sheet according to (1), wherein the basis weight of the at least one of the second layer and the first layer is 0.01% of the total basis weight of the paper layer. 19%~30%.

(12) The paper layer of the packaging composite sheet according to (1), wherein:

The second fiber is hardwood fiber, and the second fiber chemical pulp is sulfate hardwood chemical pulp;

In each of the first layer, the intermediate layer and the second layer, the content of the second fiber chemical pulp is lower than the content of the first fiber chemical pulp.

(13) The paper layer of the packaging composite sheet according to (1), wherein:

The middle layer also includes wood mechanical pulp or wood mechanochemical pulp;

The wood mechanical pulp and the wood mechanochemical pulp are absent from the second layer and the first layer.

(14) The paper layer of the packaging composite sheet according to (13), wherein:

The middle layer also includes the wood mechanical pulp;

The wood mechanical pulp includes a second fiber mechanical pulp having a second fiber;

The second fiber is hardwood fiber, and the second fiber mechanical pulp is hardwood mechanical pulp.

(15) The paper layer of the packaging composite sheet according to (14), wherein the broadleaf mechanical pulp in the middle layer accounts for 40% to 50% by mass of the middle layer.

(16) The paper layer of the packaging composite sheet according to (15), wherein the mass percentage of the broadleaf mechanical pulp in the middle layer in the middle layer is 43% to 48%.

(17) The paper layer of the packaging composite sheet according to (1) also includes:

Coating, in the thickness direction of the paper layer, the coating layer is stacked with the first layer and is located on the opposite side to the middle layer,

Wherein, the coating is configured to have a printed pattern.

(18) The paper layer of the packaging composite sheet according to (17), wherein the coating layer includes an inorganic non-metallic material.

(19) The paper layer of the packaging composite sheet according to (18), wherein the inorganic non-metal material includes china clay.

(20) The paper layer of the packaging composite sheet according to (17), wherein the basis weight of the coating layer is 6% to 9% of the total basis weight of the paper layer.

(21) The paper layer of the packaging composite sheet according to (20), wherein the thickness of the coating layer is 4% to 5% of the total thickness of the paper layer.

(22) A composite sheet for packaging, including the paper layer according to any one of (1) to (21).

(23) The packaging composite sheet according to (22), wherein the packaging composite sheet includes an inner surface and an outer surface opposite in the thickness direction thereof, and the first layer of the paper layer is disposed adjacent to The outer surface, the second layer of the paper layer is disposed close to the inner surface, and the packaging composite sheet further includes:

A sealing layer, in the thickness direction of the paper layer, the sealing layer is stacked with the second layer of the paper layer and is located on the opposite side to the middle layer,

Wherein, the sealing layer is configured to seal the packaging composite sheet under the action of thermal activation or ultrasonic activation.

(24) A packaging container including the packaging composite sheet according to (22).

(25) A method for manufacturing a paper layer of a packaging composite sheet, including: forming a paper layer; wherein the forming a paper layer includes:

Forming a first layer, a second layer and an intermediate layer between the first layer and the second layer, wherein the first layer, the intermediate layer and the second layer each comprise wood chemical pulp , the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the fiber length of the first fiber being greater than the fiber length of the second fiber;

(26) The method for manufacturing a paper layer of a packaging composite sheet according to (25), wherein the first layer, the second layer, and an intermediate layer between the first layer and the second layer are formed. Layers include:

providing wet pulp to which starch and/or dry strength agents are added; and

The wet pulp is applied to the forming device and dried.

(27) The method for manufacturing a paper layer of a packaging composite sheet according to (26), wherein only a dry strength agent is added to the wet pulp, and the dosage of the dry strength agent is 5 to 10 kg/t.

(28) A composite sheet for packaging, including a paper layer and a sealing layer, the sealing layer being used in the packaging The composite sheet is disposed on the first side of the paper layer in the thickness direction, wherein the internal bonding strength of the paper layer is 190-230 J/m2.

(29) The packaging composite sheet according to (28), wherein the raw material of the paper layer is dry pulp, and the internal bonding strength of the paper layer is 210-230 J/m2.

(30) The packaging composite sheet according to (29), wherein the density of the paper layer is 700-760kg/m3.

(31) The packaging composite sheet according to (30), wherein the density of the paper layer is 720-750kg/m3.

(32) The packaging composite sheet according to (30), wherein the thickness of the paper layer is 275-295 μm.

(33) The packaging composite sheet according to (32), wherein the thickness of the paper layer is 280-290 μm.

(34) The packaging composite sheet according to (30), wherein the paper layer has a basis weight of 205-218 g/m2.

(35) The packaging composite sheet according to any one of (28) to (34), wherein the oxygen permeability of the portion of the packaging composite sheet that does not have an indentation line is 0.3-0.8 cm3/ (m2·24h·0.1MPA).

(36) The packaging composite sheet according to (35), wherein the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.5-0.6cm3/(m2·24h·0.1MPA ).

(37) The packaging composite sheet according to any one of (28) to (34), wherein the dust level of the packaging composite sheet is: the packaging composite sheet used to form 1000 packages The dust level is less than 10g.

(38) The packaging composite sheet according to any one of (28) to (34), wherein the paper layer is composed of three fiber layers.

(39) The packaging composite sheet according to any one of (28) to (34), further comprising a barrier layer disposed on the paper layer in the thickness direction of the packaging composite sheet. The first side is between the paper layer and the sealing layer and/or is provided on a second side of the paper layer opposite to the first side.

(40) The packaging composite sheet according to (39), wherein:

The material of the sealing layer is a heat-activatable polymer or an ultrasonic-activatable polymer;

The barrier layer is made of at least one material selected from the group consisting of high molecular polymers, metal oxides, non-metal oxides and metals.

(41) A packaging sleeve including the packaging composite sheet according to any one of (28) to (40).

(42) A packaging container including the packaging composite sheet according to any one of (28) to (40).

(43) A method of manufacturing composite sheet for packaging, including:

Forming a paper layer includes: providing wet pulp; and applying the wet pulp to a forming device and drying to form the paper layer; and

Forming a sealing layer, the sealing layer is formed on the first side of the paper layer in the thickness direction of the packaging composite sheet, wherein,

The forming the paper layer further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230 J/m2.

(44) The manufacturing method according to (43), wherein,

The providing wet pulp includes: providing dry pulp, breaking up the dry pulp and diluting it with a solution to obtain the wet pulp; and

The method further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230 J/m2.

(45) The manufacturing method according to (43), wherein the internal bonding strength of the paper layer is controlled by at least one of the following means:

Method 1: Control the beating degree of the wet pulp;

Method 2: Control the ratio between soft-leaf pulp and broad-leaf pulp in the wet pulp;

Mode 3: Control the amount of starch and/or dry strength agent added to the wet pulp; and

Mode 4: Control the amount of starch and/or dry strength agent applied between each fiber layer of the paper layer.

(46) A paper layer of a packaging composite sheet, the paper layer including, in its thickness direction, a first layer, a second layer, and an intermediate layer between the first layer and the second layer. layer, wherein the first layer, the middle layer and the second layer each include wood chemical pulp, the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers. Fiber chemical pulp, the fiber length of the first fiber is greater than the fiber length of the second fiber;

Wherein, the content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer;

Wherein, the internal bonding strength of the paper layer is 190-230J/m ² .

(47) The paper layer according to (46), wherein the raw material of the paper layer is dry pulp, and the The internal bonding strength of the paper layer is 210-230J/m ² .

(48) The paper layer according to (47), wherein the density of the paper layer is 700-760 kg/m ³ .

(49) The paper layer according to (48), wherein the density of the paper layer is 720-750 kg/m ³ .

(50) The paper layer according to (48), wherein the thickness of the paper layer is 275-295 μm.

(51) The paper layer according to (50), wherein the thickness of the paper layer is 280-290 μm.

(52) The paper layer according to (48), wherein the basis weight of the paper layer is 205-218 g/m ² .

(53) The paper layer according to any one of (46) to (52), wherein the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.3-0.8cm ³ /(m ² ·24h·0.1MPA).

(54) The paper layer according to (53), wherein the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.5-0.6cm ³ /(m ² ·24h·0.1MPA) .

(55) The paper layer according to any one of (46) to (52), wherein the dust level of the packaging composite sheet is: the dust level of the packaging composite sheet used to form 1000 packages Less than 10g.

(56) The paper layer according to any one of (46) to (52), wherein the paper layer is composed of the first layer, the second layer and the middle layer.

(57) A composite sheet for packaging, including the paper layer according to any one of (46 to 56).

(58) The composite sheet for packaging according to (57), further including:

a sealing layer disposed on the first side of the paper layer in the thickness direction of the packaging composite sheet; and

A barrier layer, which is disposed on the first side of the paper layer in the thickness direction of the packaging composite sheet and is located between the paper layer and the sealing layer and/or is disposed on the paper The second side of the layer opposite the first side.

(59) The packaging composite sheet according to (58), wherein the material of the sealing layer is a heat-activatable polymer or an ultrasonic-activatable polymer;

(60) A packaging container including the packaging composite sheet according to (58) or (59).

(61) A method for manufacturing a paper layer of a composite sheet for packaging, including:

form paper layer;

Wherein, the forming the paper layer includes: forming a first layer, a second layer and an intermediate layer between the first layer and the second layer, wherein the first layer, the intermediate layer and the The second layer each includes wood chemical pulp, and the wood chemical pulp includes a first fiber chemical pulp with a first fiber and a a second fiber chemical pulp having second fibers, the fiber length of the first fiber being greater than the fiber length of the second fiber;

Wherein, forming the paper layer also includes:

Provide wet pulp;

applying the wet pulp to a forming device and drying to form the paper layer; and

The internal bonding strength of the paper layer is controlled so that the internal bonding strength of the paper layer is 210-230J/m2.

(62) The manufacturing method according to (61), wherein,

(63) The manufacturing method according to (61), wherein the internal bonding strength of the paper layer is controlled by at least one of the following means:

Method 1: Control the beating degree of the wet pulp;

(64) The manufacturing method according to (61), further comprising:

A sealing layer is formed on the first side of the paper layer in the thickness direction of the packaging composite sheet.

(65) A composite sheet for packaging, including:

Paper layer and sealing layer, the sealing layer is disposed on the first side of the paper layer in the thickness direction of the packaging composite sheet, wherein the internal bonding strength of the paper layer is 190-230J/m ² ;

Wherein, the paper layer includes a stacked first layer, a second layer and an intermediate layer between the first layer and the second layer in its thickness direction, wherein the first layer, the The middle layer and the second layer each include wood chemical pulp, the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the fiber length of the first fibers Greater than the fiber length of the second fiber;

(66) The composite sheet for packaging according to (65), wherein:

(67) The composite sheet for packaging according to (66), wherein:

The mass percentage of the sulfate needle chemical pulp in the second layer of the second layer is greater than or equal to 97%.

(68) The packaging composite sheet according to (67), wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is greater than or equal to 112%.

(69) The packaging composite sheet according to (68), wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is 100%.

(70) The composite sheet for packaging according to (66), wherein:

(71) The composite sheet for packaging according to (70), wherein:

(72) The composite sheet for packaging according to (71), wherein:

(73) The composite sheet for packaging according to (70), wherein:

(74) The composite sheet for packaging according to (73), wherein:

(75) The packaging composite sheet according to any one of (65) to (74), wherein the basis weight of the at least one of the second layer and the first layer is that of the paper layer. 19% to 30% of the total weight.

(76) The packaging composite sheet according to any one of (65) to (74), wherein:

(77) The packaging composite sheet according to any one of (65) to (74), wherein:

(78) The composite sheet for packaging according to (77), wherein:

The middle layer also includes the wood mechanical pulp;

(79) The packaging composite sheet according to (78), wherein the broadleaf mechanical pulp in the intermediate layer accounts for 40% to 50% by mass of the intermediate layer.

(80) The packaging composite sheet according to (79), wherein the mass percentage of the broadleaf mechanical pulp in the middle layer in the middle layer is 43% to 48%.

(81) The packaging composite sheet according to any one of (65)-(74), further including:

Wherein, the coating is configured to have a printed pattern.

(82) The packaging composite sheet according to (81), wherein the coating layer includes an inorganic non-metallic material.

(83) The packaging composite sheet according to (82), wherein the inorganic non-metal material includes china clay.

(84) The packaging composite sheet according to (81), wherein the basis weight of the coating layer is 6% to 9% of the total basis weight of the paper layer.

(85) The packaging composite sheet according to (84), wherein the thickness of the coating layer is 4% to 5% of the total thickness of the paper layer.

(86) The composite sheet for packaging according to any one of (65)-(74),

Wherein, the packaging composite sheet includes an inner surface and an outer surface opposite in its thickness direction, the first layer of the paper layer is arranged close to the outer surface, and the second layer of the paper layer is arranged close to the outer surface. the inner surface;

Wherein, in the thickness direction of the paper layer, the sealing layer is stacked with the second layer of the paper layer and is located on the opposite side to the middle layer;

(87) A packaging sleeve including the packaging composite sheet according to any one of (65) to (86).

(88) A packaging container including the packaging composite sheet according to any one of (65) to (86).

(89) A method of manufacturing composite sheets for packaging, including:

Forming a sealing layer, the sealing layer is formed on the first side of the paper layer in the thickness direction of the packaging composite sheet,

Wherein, forming the paper layer further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230J/m ² ;

Wherein, forming the paper layer includes:

(90) The method for manufacturing a paper layer of a packaging composite sheet according to (89), wherein the first layer, the second layer, and an intermediate layer between the first layer and the second layer are formed Layers include:

providing wet pulp to which starch and/or dry strength agents are added; and

The wet pulp is applied to the forming device and dried.

(91) The method for manufacturing a paper layer of a packaging composite sheet according to (90), wherein only a dry strength agent is added to the wet pulp, and the dosage of the dry strength agent is 5 to 10 kg/t.

In this article, there are the following points to note:

(1) The drawings of the embodiments of this disclosure only refer to structures related to the embodiments of this disclosure, and other structures may refer to common designs.

(2) Without conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

The above descriptions are only exemplary embodiments of the present disclosure and are not used to limit the scope of the present disclosure, which is determined by the appended claims.

Claims

A paper layer of a packaging composite sheet, the paper layer including in its thickness direction a first layer, a second layer and an intermediate layer located between the first layer and the second layer, wherein , the first layer, the middle layer and the second layer all include wood chemical pulp, and the wood chemical pulp includes a first fiber chemical pulp with first fibers and a second fiber chemical pulp with second fibers. , the fiber length of the first fiber is greater than the fiber length of the second fiber;

Wherein, the content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer.
The paper layer of the packaging composite sheet according to claim 1, wherein:

The first fiber is softwood fiber, and the first fiber chemical pulp is sulfate softwood chemical pulp;

The content of the sulfate softwood chemical pulp in at least one of the second layer and the first layer is higher than the content of the sulfate softwood chemical pulp in the middle layer.
The paper layer of the packaging composite sheet according to claim 2, wherein:

The content of the sulfate softwood chemical pulp in the second layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and

The mass percentage of the sulfate needle chemical pulp in the second layer of the second layer is greater than or equal to 70%.
The paper layer of the packaging composite sheet according to claim 3, wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is greater than or equal to 85%.
The paper layer of the packaging composite sheet according to claim 4, wherein the mass percentage of the sulfate softwood chemical pulp included in the second layer to the second layer is 100%.
The paper layer of the packaging composite sheet according to claim 2, wherein:

The content of the sulfate softwood chemical pulp in the first layer is higher than the content of the sulfate softwood chemical pulp in the middle layer; and

The mass percentage of the sulfate needle chemical pulp in the first layer of the first layer is greater than or equal to 70%.
The paper layer of the packaging composite sheet according to claim 6, wherein:

The content of the sulfate softwood chemical pulp in the first layer is equal to the content of the sulfate softwood chemical pulp in the second layer.
The paper layer of the packaging composite sheet according to claim 7, wherein:

The mass percentage of the sulfate needle chemical pulp in the first layer of the first layer is 75% to 85%;

The sulfate needle chemical pulp in the second layer accounts for 75% to 85% of the mass of the second layer.
The paper layer of the packaging composite sheet according to claim 6, wherein:

The content of the sulfate softwood chemical pulp in the first layer is lower than the content of the sulfate softwood chemical pulp in the second layer.
The paper layer of the packaging composite sheet according to claim 9, wherein:

The mass percentage of the sulfate needle chemical pulp in the first layer of the first layer is 75% to 85%;

The sulfate needle chemical pulp in the second layer accounts for 95% to 100% of the mass of the second layer.
The paper layer of the packaging composite sheet according to claim 1, wherein the grammage of at least one of the second layer and the first layer is 19% to 19% of the total grammage of the paper layer. 30%.
The paper layer of the packaging composite sheet according to claim 1, wherein:

The second fiber is hardwood fiber, and the second fiber chemical pulp is sulfate hardwood chemical pulp;

In each of the first layer, the intermediate layer and the second layer, the content of the second fiber chemical pulp is lower than the content of the first fiber chemical pulp.
The paper layer of the packaging composite sheet according to claim 1, wherein:

The middle layer also includes wood mechanical pulp or wood mechanochemical pulp;

The wood mechanical pulp and the wood mechanochemical pulp are absent from the second layer and the first layer.
The paper layer of the packaging composite sheet according to claim 13, wherein:

The middle layer also includes the wood mechanical pulp;

The wood mechanical pulp includes a second fiber mechanical pulp having a second fiber;

The second fiber is hardwood fiber, and the second fiber mechanical pulp is hardwood mechanical pulp.
The paper layer of the packaging composite sheet according to claim 14, wherein the mass percentage of the broadleaf mechanical pulp in the middle layer of the middle layer is 40% to 50%.
The paper layer of the packaging composite sheet according to claim 15, wherein the mass percentage of the broadleaf mechanical pulp in the middle layer of the middle layer is 43% to 48%.
The paper layer of the packaging composite sheet according to claim 1, further comprising:

Coating, in the thickness direction of the paper layer, the coating layer is stacked with the first layer and is located on the opposite side to the middle layer,

Wherein, the coating is configured to have a printed pattern.
The paper layer of the packaging composite sheet according to claim 17, wherein the coating layer includes an inorganic non-metallic material.
The paper layer of the packaging composite sheet according to claim 18, wherein the inorganic non-metallic material includes china clay.
The paper layer of the packaging composite sheet according to claim 17, wherein the basis weight of the coating is 6% to 9% of the total basis weight of the paper layer.
The paper layer of the packaging composite sheet according to claim 20, wherein the thickness of the coating is 4% to 5% of the total thickness of the paper layer.
A composite sheet for packaging, comprising the paper layer according to any one of claims 1 to 21.
The packaging composite sheet according to claim 22, wherein the packaging composite sheet includes an inner surface and an outer surface opposite in the thickness direction thereof, and the first layer of the paper layer is disposed close to the outer surface. surface, the second layer of the paper layer is disposed close to the inner surface, and the packaging composite sheet further includes:

A sealing layer, in the thickness direction of the paper layer, the sealing layer is stacked with the second layer of the paper layer and is located on the opposite side to the middle layer,

Wherein, the sealing layer is configured to seal the packaging composite sheet under the action of thermal activation or ultrasonic activation.
A packaging container comprising the packaging composite sheet according to claim 22.
A method of manufacturing a paper layer of a packaging composite sheet, including: forming a paper layer; wherein the forming a paper layer includes:

Forming a first layer, a second layer and an intermediate layer between the first layer and the second layer, wherein the first layer, the intermediate layer and the second layer each comprise wood chemical pulp , the wood chemical pulp includes a first fiber chemical pulp having first fibers and a second fiber chemical pulp having second fibers, the fiber length of the first fiber being greater than the fiber length of the second fiber;

Wherein, the content of the first fiber chemical pulp in at least one of the second layer and the first layer is higher than the content of the first fiber chemical pulp in the middle layer.
The method for manufacturing a paper layer of a packaging composite sheet according to claim 25, wherein the The forming of the first layer, the second layer and the intermediate layer between the first layer and the second layer includes:

providing wet pulp to which starch and/or dry strength agents are added; and

The wet pulp is applied to the forming device and dried.
The method for manufacturing a paper layer of a packaging composite sheet according to claim 26, wherein only a dry strength agent is added to the wet pulp, and the dosage of the dry strength agent is 5 to 10 kg/t.
A composite sheet for packaging, including a paper layer and a sealing layer, the sealing layer being disposed on the first side of the paper layer in the thickness direction of the composite sheet for packaging, wherein the paper layer The internal bonding strength is 190-230J/m 2 .
The packaging composite sheet according to claim 28, wherein the raw material of the paper layer is dry pulp, and the internal bonding strength of the paper layer is 210-230 J/m 2 .
The packaging composite sheet according to claim 29, wherein the density of the paper layer is 700-760kg/m 3 .
The packaging composite sheet according to claim 30, wherein the density of the paper layer is 720-750kg/m 3 .
The packaging composite sheet according to claim 30, wherein the thickness of the paper layer is 275-295 μm.
The packaging composite sheet according to claim 32, wherein the thickness of the paper layer is 280-290 μm.
The packaging composite sheet according to claim 30, wherein the basis weight of the paper layer is 205-218g/m 2 .
The packaging composite sheet according to any one of claims 28 to 34, wherein the oxygen permeability of the portion of the packaging composite sheet without indentation lines is 0.3-0.8cm 3 /(m 2 · 24h·0.1MPA).
The packaging composite sheet according to claim 35, wherein the oxygen permeability of the portion without indentation lines of the packaging composite sheet is 0.5-0.6cm 3 /(m 2 ·24h·0.1MPA) .
The packaging composite sheet according to any one of claims 28 to 34, wherein the dust level of the packaging composite sheet is: the dust level of the packaging composite sheet used to form 1000 packages is less than 10 g .
The packaging composite sheet according to any one of claims 28 to 34, wherein the paper layer is composed of three fiber layers.
The packaging composite sheet according to any one of claims 28 to 34, further comprising a barrier layer disposed on the first side of the paper layer and positioned in the thickness direction of the packaging composite sheet. Between the paper layer and the sealing layer and/or disposed on a second side of the paper layer opposite to the first side.
The packaging composite sheet according to claim 39, wherein

The material of the sealing layer is a heat-activatable polymer or an ultrasonic-activatable polymer;

The barrier layer is made of at least one material selected from the group consisting of high molecular polymers, metal oxides, non-metal oxides and metals.
A packaging sleeve comprising the packaging composite sheet according to any one of claims 28-40.
A packaging container, including the packaging composite sheet according to any one of claims 28-40.
A manufacturing method of composite sheet for packaging, including:

Forming a paper layer includes: providing wet pulp; and applying the wet pulp to a forming device and drying to form the paper layer; and

Forming a sealing layer, the sealing layer is formed on the first side of the paper layer in the thickness direction of the packaging composite sheet, wherein,

The forming the paper layer further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230 J/m 2 .
The manufacturing method according to claim 43, wherein

The providing wet pulp includes: providing dry pulp, breaking up the dry pulp and diluting it with a solution to obtain the wet pulp; and

The method further includes: controlling the internal bonding strength of the paper layer so that the internal bonding strength of the paper layer is 210-230 J/m 2 .
The manufacturing method according to claim 43, wherein the internal bonding strength of the paper layer is controlled by at least one of the following ways:

Method 1: Control the beating degree of the wet pulp;

Method 2: Control the ratio between soft-leaf pulp and broad-leaf pulp in the wet pulp;

Mode 3: Control the amount of starch and/or dry strength agent added to the wet pulp; and

Mode 4: Control the amount of starch and/or dry strength agent applied between each fiber layer of the paper layer.