Development status and new trend of packaging pape

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Development status and new trend of China's packaging paper market

I. Introduction

packaging paper is a large category of paper products, including paper (sheet) and paperboard used in packaging industry and packaging printing. According to the statistics of China Paper Association in August 2003, in 2002, China's consumption of packaging paper accounted for 56% of the country's total annual paper production, ranking the first (followed by cultural paper, accounting for 24%, household paper, accounting for about 8%, and other small shares). However, due to the small base of this percentage, China still needs to import a certain amount of packaging paper to fill the demand "gap" of the domestic market

there are more than 10000 packaging enterprises (above the county level) in China, with nearly 2 million employees and 62 billion yuan of fixed assets in the packaging industry, which are respectively subordinate to the departments of light industry, electronics, military industry, foreign trade, civil affairs, machinery, township enterprises and so on. With the new situation of China's rapid economic development, the packaging task of domestic and export commodities is becoming more and more arduous, the market demand for packaging paper is increasing, and the consideration of paper quality is becoming more and more strict. As a result, the paper industry is facing an increasingly heavy task, which also urges the further improvement of China's paper technology

II. Classification

packaging paper can be divided into five kinds: ordinary packaging paper, special packaging paper, trademark packaging paper, oil-proof packaging paper and moisture-proof packaging paper. Ordinary packaging paper is strong and tough, which is used for general packaging, such as kraft paper, chicken skin paper, etc; Special packaging paper is named according to its purpose, and its properties are also different. For example, fruit packaging paper is thin and soft, and photosensitive protective paper is black and opaque; Trademark wrapping paper is used for packaging after printing, such as candy wrapping paper; Oil proof packaging paper has the performance of preventing oil penetration, such as vegetable parchment and butter paper; Moisture proof packaging paper has moisture resistance, such as Cypress oil paper, aluminum foil paper, etc. This is a previous understanding. Today's packaging paper is "farewell day", which is impressive

according to rough statistics, there are about dozens of kinds of packaging paper. If divided according to the actual use, there are (1) paper types for general commodity packaging: such as kraft paper, kraft linerboard, coated paper, cast coated paper, coated white paperboard, corrugated base paper, corrugated boxboard, honeycomb paperboard, etc; (2) Paper for food and cosmetics packaging: such as cellophane, translucent paper, postal paper, fresh-keeping paper, food parchment, etc; (3) Paper for moisture-proof, rust proof and precision mechanical products packaging: such as aluminized paper, aluminum foil paper, needle wrapping paper, composite paper, neutral stone wax paper, vapor phase rust proof paper, etc; (4) Paper for cement and chemical fertilizer packaging: such as paper bag paper, stretch paper bag paper, etc; (5) Paper for the packaging of photosensitive materials: such as photosensitive protective paper and black (opaque) paper; (6) Paper for medical devices and disinfection packaging: such as surgical packaging paper, medical paper, etc; (7) Paper for gunpowder and detonator packaging: such as gunpowder packaging paper, conduit paper, signal paper, etc; (8) Paper for special packaging: such as compressed biscuit paper, fresh-keeping paper, fish egg paper, etc

III. characteristics

the characteristics of packaging paper can be divided into the following five aspects (note that some are the same as other kinds of paper and some are different):

(1) physical properties

paper is mainly composed of plant fibers (pulp), and some are mixed with non plant fibers (such as glass fiber, synthetic fiber, etc.). The first index to measure paper is "quantitative" (also known as gram weight). The unit is gram/square meter, which is commonly expressed in GSM

the thickness and tightness of paper are two other physical indexes. The former is the vertical distance between the two sides of the paper (front and back), and the latter is the mass of paper per unit volume. They affect the physical, mechanical and printing properties of paper

the fibers in the paper are intertwined with each other, and the existing gaps make it breathable. The value for measuring its air permeability is called air permeability. The cheap bit of a single price is m/PA · s. The surface of the paper is represented by "smoothness". Air permeability has an indirect relationship with the mechanical strength of the paper and a direct relationship with the printing performance, because it has an impact on the absorption of the ink. The smoothness is more closely related to the printing performance. For packaging paper, these two indicators are easy to be ignored, resulting in defects in outer packaging printing

the uniformity of paper, that is, uniformity, affects the physical, mechanical and optical properties of paper. Various defects exposed on the paper surface (commonly known as "paper disease"), such as dust, spots, holes, holes, folds, cracks, streaks, etc., are unfavorable to packaging or packaging printing. At present, China's papermaking technology is generally improved, the quality of packaging paper is significantly improved, and the frequency of "paper disease" is greatly reduced

the above physical properties involve the measurement, transportation and cost of packaging paper, and are also the basic properties common to general paper

(2) chemical properties

the chemical properties of paper include fiber and other components. It usually refers to the water, ash, acid-base (pH value), copper price, water-soluble chloride, etc. contained in the paper

generally, the moisture content of paper is 6% ~ 8%, which often changes according to environmental changes. The moisture content of paper is too high, which means "taking money to buy water" for users; Too low means that the paper may be brittle, damaged and other problems. The time between packaging paper and the external environment is longer and more than ordinary paper, so we should pay more attention to the change of its moisture

ash is the inorganic matter contained in paper. Its sources are: first, inorganic substances contained in papermaking raw materials themselves. Wood contains less ash, less than 1%. Grasses contain high ash content, about 3% ~ 5%, and some straw contain 12%. 2、 In the process of papermaking production, the inorganic residue brought by chemical reaction with chemical agents. 3、 Inorganic matter introduced after filler and coating are applied to paper. Ash has little effect on general packaging paper, but has a great impact on the manufacture of cellophane

acidity and alkalinity refers to the condition of hydrogen ions or hydrogen and oxygen ions contained in paper. It is usually expressed by pH value. High acid paper has poor stability and durability, gradually darkened color and low mechanical strength. This kind of paper is also not suitable for packaging food or metal products. During printing, it may also cause corrosion and contamination of the printing plate and affect the quality of the printed matter

and share with the industry the latest developments and development trends in this market field. Using

copper price is to determine the number of reductive end groups in the cellulose molecular chain of paper. Originally, the cellulose molecular chain was "intact", and its copper price was very low, that is, the number of terminal groups was small. Once subjected to oxidation and hydrolysis, the molecular chain breaks. As a result, more terminal groups are exposed, and the copper price rises rapidly. Therefore, the high copper price of paper indicates that the paper is deteriorated and the durability and strength will be reduced

the index of water-soluble chloride is very meaningful for some packaging paper, such as antirust paper, neutral paper, food packaging paper, etc. Because the residual chloride is harmful to the application of this kind of packaging paper. Conductometric titration is usually used to check whether the water-soluble chloride contained in the paper "exceeds the standard", so as to determine the limit of the selection of the control system except user elements

the chemical properties of packaging paper have different effects on the safety and durability of paper

(3) mechanical properties

tensile strength of paper, formerly known as tensile strength. When subjected to external force, the fiber is forced to stretch and the paper begins to elongate; After the external force is cancelled, the fiber shrinks automatically and the paper returns to its original state. The general requirements for packaging paper are good mechanical properties and not too small strength

toughness is an important index of packaging paper, which has large toughness and less damage; Small toughness and many damages. Another index, stiffness, is the bending resistance of paper, that is, its ability to support self weight. The stiffness of corrugated base paper and carton board is very important. The stiffness of carton determines its use value

burst resistance is the maximum pressure that a certain area of paper can withstand when subjected to constant pressure until it breaks. In general, the burst resistance is about twice the longitudinal tensile strength of the paper sample per unit width. If the burst resistance is the performance under "static", then the impact strength is the reflection under "dynamic". For example, stretch bag paper has high impact strength, which makes it not easy to break even under the sudden impact of external force

folding resistance is the number of times when the paper is folded back and forth under a certain tension. In the process of making cartons and cartons of different sizes, the white cardboard and cartons in the packaging paper must be folded for many times without breaking, so it is required to have high folding resistance

curliness is the "shape" change of paper affected by humidity, temperature or other factors. When the moisture absorption of the front, back, middle and periphery of the paper is uneven, curling occurs due to local deformation. Generally speaking, when it is excessively wet, the front curl occurs; When it is too dry, it is curled on the opposite side. In addition, curl is related to the size change of paper, and is affected by thickness, uniformity, tightness and scalability

(4) optical properties

paper has different reactions to light irradiation. For example, after total reflection, the vision acting on human eyes is whiteness; If it is partially reflected and partially absorbed, it is opacity; If it is diffused and reflected at a certain angle, it is glossiness. The above three optical properties are closely related to the emission light source, observation conditions, receiving device, etc. Generally, the wavelength of the light source is about 360 nm, the irradiation angle is 45 degrees, the reflection angle is 0 degrees (i.e. vertical), and the receiver is selenium photocell or photocell

the whiteness of paper is an important index of white packaging paper and packaging printing paper. The whiteness of the paper is determined according to the requirements of the outer packaging of the goods. Generally, 65% ~ 70% whiteness is adopted. Advanced is 80% ~ 85% whiteness; Opacity can not be ignored for packaging and printing. For printing paper, the higher the opacity, the better. There are many factors affecting opacity, such as thickness, tightness, filler amount, etc; There are two kinds of gloss: one is contrast gloss, which is suitable for ordinary white paper, and the other is mirror gloss, which is suitable for paper processed by super calender. The paper used for high-grade gift packaging box has high requirements for gloss

(5) printing performance

in packaging paper, printing suitability is a very important index, which refers to the comprehensive evaluation of the way in which paper, printing plate and ink cooperate with each other to achieve the optimal actual effect when managing the production of printed matter with the necessary speed, quantity and quality under the locked printing mode

surface strength (vertical strength) refers to the ability to resist delamination and tear perpendicular to the plane on the unit area of the paper, and also includes the ability to resist powder and hair loss. The so-called poor surface strength, if you take the coated white paperboard as an example, is that the filler particles of the coating have poor adhesion, the adhesion between the coating and the base paper is poor, and there is not enough bonding strength between the base paper fibers. Therefore, in the printing process, the ink film will peel off the coating particles and fine fibers, which is the phenomenon of powder and hair loss. In order to strengthen the surface strength of paper, we should make more efforts in papermaking raw materials and processing technology to ensure that the quality of paper meets the use requirements. The measurement methods of surface strength include: wax rod method, tensile test method, roughening critical speed method, etc. Porosity is a "mirror" of the internal porous structure of paper, which is often based on the volume occupied by the air in the paper

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