Paper cartons related indicators
A common base paper
(a) kraft paper
Kraft paper is a widely used packaging paper and is mainly used to make all kinds of cardboard noodles and hangings. High-quantity kraft paper is also used as face and interior paper for corrugated board.
According to different proportions of sizing agent, kraft paper is divided into No. 1 and No. 2. The raw material of No. 1 kraft paper is 100% natural coniferous kraft wood pulp, No. 2 kraft paper is mainly sulphate wood pulp, and part of sulphate bamboo is added. Pulp and cotton stalks. Natural sulphate wood pulp fibers are very strong, yellow-brown and difficult to bleach.
Kraft paper requires a large degree of sizing and is very resistant to water. Kraft paper has a high physical strength, the degree of folding resistance of up to 300 times, bursting strength of up to 400 Kpa, tensile strength of up to 600 ~ 800Kpa, it also has a soft, strong, flexible and so on.
b) Board paper
Boxboard paper is used to make corrugated board paper or liner paper, requiring a smooth surface, a good appearance, and higher requirements in the degree of folding, bursting, water resistance and so on. At present, the linerboard paper is divided into four grades: (1) special-size linerboard (kraft linerboard), with over 50% chemical pulp, bamboo pulp and other long fiber noodles, less than 50% waste linen, waste paper, brown Ground wood pulp and semi-chemical pulp as bottom layer. Some foreign countries use all sulphate coniferous wood pulp or a small amount of waste pulp production, the strength indicators are higher. (2) No. 1 linerboard (strong boxboard), made with 30% or more of long fiber pulp and other waste pulp, chemical grass pulp, brown ground wood pulp, semi-chemical pulp, etc. (3) No. 2 linerboard, ie ordinary linerboard, is made from chemical pulp, brown ground wood pulp and semi-chemical pulp. (4) No. 3 linerboard (light-load linerboard) is made from chemical pulp or semi-chemical pulp.
The four grades of linerboard have various grades of performance indicators, especially the strength of linerboard, which is suitable for the manufacture of fine, valuable and export corrugated cardboard packaging for refrigerated goods.
(c) Corrugated paper
Corrugated paper is mainly used as corrugating medium for corrugated paperboard. It is pressure-formed into corrugated corrugated during the production process and requires good tensile strength and ring-crush strength. Corrugated paper is divided into three types according to different raw materials: chemical wood pulp corrugated paper, straw pulp corrugated paper and waste paper corrugated paper. Corrugated paper can also be divided into several grades according to different performance indicators. It is suitable for the production of corrugated cardboard with different requirements.
(d) Grass paper (also known as yellow paper)
Grass board paper uses straw and wheat straw as main raw materials, and sorghum straw, corn stalks, bagasse, etc. are also widely used. Grass fiber paper fiber is rough and loose. Due to high lignin content, the paper is stiff and has a high level of rigidity. Degree and hardness, but brittle, folding and low toughness, can not be repeated folding, wide range of uses grass board, 70% of China for the production of various cartons, but also for the manufacture of various liner materials.
(5) Whiteboard paper
Whiteboard paper is more advanced packaging paper. This kind of paper is generally a multi-layered structure, divided into white and white paper and white paper. The proportion of pulp in the manufacture of whiteboard paper varies from country to country. The surface layer generally uses bleached chemical wood pulp. As for the bottom layer, the Nordic countries use chemical wood pulp and ground wood pulp, Japan uses selected waste pulp, and China uses roots, waste pulp or ground wood pulp. The sandwiched Nordic countries generally use chemical wood pulp and ground wood pulp, and Japan uses waste pulp. China uses mash, waste pulp or groundwood pulp.
The stiffness of whiteboard paper depends largely on the strength of the paperboard top and bottom layers. According to studies, the stiffness of the surface layer and the bottom layer accounts for 72.7% of the total stiffness of the board. Therefore, in order to reduce the cost, the high-strength pulp is often used as the surface and the inner layer, while the interlayer uses the poor-quality pulp.
II. Physical properties of base paper
(1) Tightness tightness refers to the mass per unit volume of paper, also known as density. Tightness is closely related to the quantitative and thickness. Because of this, it is the most basic of the physical properties of paper and paperboard. The characteristics.
Tightness refers to the degree of firmness and relaxation of the paper. The tightness of the paper or paperboard hinders the diffusion and penetration of the adhesive between the paper, which is not conducive to adhesion, so the greater the tightness, the higher the adhesive requirements, by changing the adhesive Formulated to meet the needs of production.
(b) The water content of paper is usually expressed as a percentage of the ratio of the weight reduced when the sample is dried to a constant weight (constant weight) at a temperature of 100-105°C and the weight of the sample before drying.
Both cardboard and cardboard are made from natural plant fibers. The plant fibers are made of cellulose. The basic property of cellulose is hydrophilicity. Therefore, general paper and paperboard also have different degrees of hydrophilicity. Therefore, the water content changes with the surrounding environment, ie, the relative humidity of the air, and eventually reaches equilibrium with it. Due to the difference in the amount of paper, raw materials, sizing, and fillers, the moisture content is inconsistent. For example, when the relative humidity is 65%, the equilibrium water content of the whiteboard paper is 6.8-8.5%. All kinds of paper and paperboard have the standard of water content, and the standard water indexes of paper and board in China are generally the balanced moisture under the relative humidity of 65% of the standard humidity, plus the allowable fluctuation range. If the normal paper standard moisture content is 7±2%, it means that the equilibrium moisture content of these products at 65% humidity is about 7%. The carton is 14±4%.
Hydrophilicity of the paper not only results in a change in the moisture content of the paper itself, but also directly affects the adhesive properties, the stretchability and the drying speed of the corrugated cardboard. When the moisture content of the binder is high, the water content of the bonded paper is low, and the two are in contact with each other; when the adhesive has less moisture and the paper is too dry, the two are in contact with each other. The capillary action does not get enough adsorption capacity, at this time the tanning of corrugated cardboard will not stick. When the moisture content of the binder is low and the moisture content of the paper is high, both can also be adhered. If the water content of both is high, the adherend cannot adsorb all the moisture in the adhesive. The excess moisture is in a free state and spreads along the direction of the paper fiber, which will cause a large area of ​​corrugated cardboard to be delaminated. If the rolled corrugated fiber is perpendicular to the direction of the base paper fiber, runaway phenomenon will occur.
The moisture content of the paper not only affects the adhesion, but also results in a variety of physical properties of the paper itself. After testing, when the water content of the paper is increased from 30% to 85%, the folding endurance is increased by about 10 times and the tensile strength is increased. .
Three kinds of corrugated cardboard
The structural design of corrugated paperboard is very scientific. The corrugated corrugations are like small arched doors that are connected one by one. They are arranged in a row and support each other to form a triangular structure. It is strong and powerful, and the plane can withstand a certain degree. Pressure, flexibility, strong cushioning, can play a role in shock protection and protection of goods.
Corrugated shapes are generally classified into U-shaped, V-shaped, and UV-shaped, depending on the radius of the arc. The peak radius of the U-shaped arc is larger and has an arc shape; the radius of the V-shaped peak is smaller and sharp; the UV type is between the two. According to experiments, the V-shaped rake is less skewed in the initial stage of compression, but it quickly breaks when it exceeds the highest point, and the U-shaped rake absorbs higher energy. When the pressure is eliminated, it can still be restored to its original state, but it is flexible. The compressive strength is not high. In addition, the V-shaped crucible saves corrugated paper and has less adhesive consumption, but it is prone to high and low defects during processing, and the corrugating roll wears quickly. UV-shaped crucibles are a combination of U-shaped and V-shaped features, which are currently widely used.
At present, there are four kinds of corrugated types in various countries of the world: A, C, B, E, and four types. The specifications are as follows:
A common base paper
(a) kraft paper
Kraft paper is a widely used packaging paper and is mainly used to make all kinds of cardboard noodles and hangings. High-quantity kraft paper is also used as face and interior paper for corrugated board.
According to different proportions of sizing agent, kraft paper is divided into No. 1 and No. 2. The raw material of No. 1 kraft paper is 100% natural coniferous kraft wood pulp, No. 2 kraft paper is mainly sulphate wood pulp, and part of sulphate bamboo is added. Pulp and cotton stalks. Natural sulphate wood pulp fibers are very strong, yellow-brown and difficult to bleach.
Kraft paper requires a large degree of sizing and is very resistant to water. Kraft paper has a high physical strength, the degree of folding resistance of up to 300 times, bursting strength of up to 400 Kpa, tensile strength of up to 600 ~ 800Kpa, it also has a soft, strong, flexible and so on.
b) Board paper
Boxboard paper is used to make corrugated board paper or liner paper, requiring a smooth surface, a good appearance, and higher requirements in the degree of folding, bursting, water resistance and so on. At present, the linerboard paper is divided into four grades: (1) special-size linerboard (kraft linerboard), with over 50% chemical pulp, bamboo pulp and other long fiber noodles, less than 50% waste linen, waste paper, brown Ground wood pulp and semi-chemical pulp as bottom layer. Some foreign countries use all sulphate coniferous wood pulp or a small amount of waste pulp production, the strength indicators are higher. (2) No. 1 linerboard (strong boxboard), made with 30% or more of long fiber pulp and other waste pulp, chemical grass pulp, brown ground wood pulp, semi-chemical pulp, etc. (3) No. 2 linerboard, ie ordinary linerboard, is made from chemical pulp, brown ground wood pulp and semi-chemical pulp. (4) No. 3 linerboard (light-load linerboard) is made from chemical pulp or semi-chemical pulp.
The four grades of linerboard have various grades of performance indicators, especially the strength of linerboard, which is suitable for the manufacture of fine, valuable and export corrugated cardboard packaging for refrigerated goods.
(c) Corrugated paper
Corrugated paper is mainly used as corrugating medium for corrugated paperboard. It is pressure-formed into corrugated corrugated during the production process and requires good tensile strength and ring-crush strength. Corrugated paper is divided into three types according to different raw materials: chemical wood pulp corrugated paper, straw pulp corrugated paper and waste paper corrugated paper. Corrugated paper can also be divided into several grades according to different performance indicators. It is suitable for the production of corrugated cardboard with different requirements.
(d) Grass paper (also known as yellow paper)
Grass board paper uses straw and wheat straw as main raw materials, and sorghum straw, corn stalks, bagasse, etc. are also widely used. Grass fiber paper fiber is rough and loose. Due to high lignin content, the paper is stiff and has a high level of rigidity. Degree and hardness, but brittle, folding and low toughness, can not be repeated folding, wide range of uses grass board, 70% of China for the production of various cartons, but also for the manufacture of various liner materials.
(5) Whiteboard paper
Whiteboard paper is more advanced packaging paper. This kind of paper is generally a multi-layered structure, divided into white and white paper and white paper. The proportion of pulp in the manufacture of whiteboard paper varies from country to country. The surface layer generally uses bleached chemical wood pulp. As for the bottom layer, the Nordic countries use chemical wood pulp and ground wood pulp, Japan uses selected waste pulp, and China uses roots, waste pulp or ground wood pulp. The sandwiched Nordic countries generally use chemical wood pulp and ground wood pulp, and Japan uses waste pulp. China uses mash, waste pulp or groundwood pulp.
The stiffness of whiteboard paper depends largely on the strength of the paperboard top and bottom layers. According to studies, the stiffness of the surface layer and the bottom layer accounts for 72.7% of the total stiffness of the board. Therefore, in order to reduce the cost, the high-strength pulp is often used as the surface and the inner layer, while the interlayer uses the poor-quality pulp.
II. Physical properties of base paper
(1) Tightness tightness refers to the mass per unit volume of paper, also known as density. Tightness is closely related to the quantitative and thickness. Because of this, it is the most basic of the physical properties of paper and paperboard. The characteristics.
Tightness refers to the degree of firmness and relaxation of the paper. The tightness of the paper or paperboard hinders the diffusion and penetration of the adhesive between the paper, which is not conducive to adhesion, so the greater the tightness, the higher the adhesive requirements, by changing the adhesive Formulated to meet the needs of production.
(b) The water content of paper is usually expressed as a percentage of the ratio of the weight reduced when the sample is dried to a constant weight (constant weight) at a temperature of 100-105°C and the weight of the sample before drying.
Both cardboard and cardboard are made from natural plant fibers. The plant fibers are made of cellulose. The basic property of cellulose is hydrophilicity. Therefore, general paper and paperboard also have different degrees of hydrophilicity. Therefore, the water content changes with the surrounding environment, ie, the relative humidity of the air, and eventually reaches equilibrium with it. Due to the difference in the amount of paper, raw materials, sizing, and fillers, the moisture content is inconsistent. For example, when the relative humidity is 65%, the equilibrium water content of the whiteboard paper is 6.8-8.5%. All kinds of paper and paperboard have the standard of water content, and the standard water indexes of paper and board in China are generally the balanced moisture under the relative humidity of 65% of the standard humidity, plus the allowable fluctuation range. If the normal paper standard moisture content is 7±2%, it means that the equilibrium moisture content of these products at 65% humidity is about 7%. The carton is 14±4%.
Hydrophilicity of the paper not only results in a change in the moisture content of the paper itself, but also directly affects the adhesive properties, the stretchability and the drying speed of the corrugated cardboard. When the moisture content of the binder is high, the water content of the bonded paper is low, and the two are in contact with each other; when the adhesive has less moisture and the paper is too dry, the two are in contact with each other. The capillary action does not get enough adsorption capacity, at this time the tanning of corrugated cardboard will not stick. When the moisture content of the binder is low and the moisture content of the paper is high, both can also be adhered. If the water content of both is high, the adherend cannot adsorb all the moisture in the adhesive. The excess moisture is in a free state and spreads along the direction of the paper fiber, which will cause a large area of ​​corrugated cardboard to be delaminated. If the rolled corrugated fiber is perpendicular to the direction of the base paper fiber, runaway phenomenon will occur.
The moisture content of the paper not only affects the adhesion, but also results in a variety of physical properties of the paper itself. After testing, when the water content of the paper is increased from 30% to 85%, the folding endurance is increased by about 10 times and the tensile strength is increased. .
Three kinds of corrugated cardboard
The structural design of corrugated paperboard is very scientific. The corrugated corrugations are like small arched doors that are connected one by one. They are arranged in a row and support each other to form a triangular structure. It is strong and powerful, and the plane can withstand a certain degree. Pressure, flexibility, strong cushioning, can play a role in shock protection and protection of goods.
Corrugated shapes are generally classified into U-shaped, V-shaped, and UV-shaped, depending on the radius of the arc. The peak radius of the U-shaped arc is larger and has an arc shape; the radius of the V-shaped peak is smaller and sharp; the UV type is between the two. According to experiments, the V-shaped rake is less skewed in the initial stage of compression, but it quickly breaks when it exceeds the highest point, and the U-shaped rake absorbs higher energy. When the pressure is eliminated, it can still be restored to its original state, but it is flexible. The compressive strength is not high. In addition, the V-shaped crucible saves corrugated paper and has less adhesive consumption, but it is prone to high and low defects during processing, and the corrugating roll wears quickly. UV-shaped crucibles are a combination of U-shaped and V-shaped features, which are currently widely used.
At present, there are four kinds of corrugated types in various countries of the world: A, C, B, E, and four types. The specifications are as follows:
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