Table of Contents
The production, manufacturing, and application of paper and paperboard have a history of nearly 2000 years. The invention of paper is of great significance for promoting the exchange, dissemination, inheritance, and development of human civilization and science and technology.
At the same time, with the rapid development of the papermaking industry, basic conditions have been created for paper and cardboard to enter the packaging industry. With the progress of paper making technology, a series of deep processing such as coating, impregnation, modification, and composite have been carried out on paper and cardboard, making the performance of paper packaging materials better meet the requirements of commercial packaging, and their application fields more extensive.
At present, paper and cardboard have become one of the packaging materials with the largest usage, the largest variety, and the most promising development prospects.
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Packaging performance of paper packaging materials
Strength performance refers to the maximum stress that a material can withstand when it ruptures under external forces, and is also the physical and mechanical strength of paper and paperboard.
For example, the tensile strength and tearing strength of paper bags, the bursting strength of cardboard, and the puncture strength of corrugated cardboard.
The strength performance of packaging materials is particularly important for the protection of goods. The strength mainly depends on the type of raw materials, quality, processing technology, surface condition, and environmental temperature and humidity of the paper.
Due to the high water absorption of plant fibers, as environmental humidity increases, the tensile strength and tear strength of paper will decrease, thereby affecting the strength of paper and cardboard.
Changes in environmental temperature and humidity can cause changes in the water balance of paper and paperboard, ultimately leading to changes in their strength performance.
Barrier and absorption performance
Paper and cardboard are porous fiber materials that have certain permeability to gases, light, and oil, and their barrier properties are greatly affected by environmental temperature and humidity.
Barrier performance includes indicators such as air permeability, water vapor transmittance, and light transmittance; Absorption performance mainly refers to water absorption, ink absorption, sizing degree, etc. These properties are particularly important for moisture-proof packaging, rust proof packaging, and fresh-keeping packaging.
Bending and compression resistance
The bending and compression resistance of paper and paperboard is an important index for the manufacturing of packing cases and boxes, which includes stiffness, ring compression strength, edge compression strength, flat compression strength, etc.
The surface properties of paper and paperboard, including roughness, smoothness, printing surface strength, and properties such as shedding, wear resistance, and adhesion, have a significant impact on the final printing effect.
The optical properties of paper and paperboard reflect their ability to reflect, transmit, and absorb projected light, giving people sensory vision that includes performance indicators such as paper whiteness, transparency, glossiness, and color.
The vast majority of packaging paper has specific requirements for optical performance, especially for cast coated cardboard used for high-end product packaging and copper coated paper used for label making, which have high requirements for paper whiteness and glossiness.
Packaging paper and cardboard must have good printability in order to produce a visually pleasing packaging. With the increasingly fierce competition for goods, the requirements for the printing effect of packaging and decoration are becoming higher and higher.
At present, in addition to the traditional lithography and intaglio printing, screen printing, flexographic printing, embossing, bronzing and other printing processes are widely used in the printing mode.
Any printing method requires paper and cardboard to have good ink absorption, surface uniformity, dimensional stability, etc. Only in this way can exquisite packaging patterns be printed.
Health and safety performance
For special purpose paper and cardboard, there are specific requirements in terms of hygiene and safety performance in addition to general performance.
For packaging paper used for food, medicine, cosmetics, etc., safety and hygiene must be tested, including heavy metal content, fluorescent substances, detection level of Escherichia coli, etc., and should be controlled within the safe range.
Packaging paper and cardboard for different purposes have different requirements for hygiene and safety performance.
Types of packaging paper and cardboard
According to the standard, paper and cardboard are generally distinguished by quantity and thickness, and those with a quantity less than 225g/m and a thickness less than 0.1mm are called paper; Paperboard with a quantity greater than 225g/m and a thickness greater than 1mm is called cardboard.
There are various types of packaging paper and cardboard, which can be divided into several categories based on processing technology, including packaging paper, packaging cardboard, processing paper, and cardboard.
The main varieties of paper used for manufacturing paper packaging products such as paper bags, wrapping, and packaging labels include kraft paper, paper bags, corrugated base paper, coated paper, chicken skin paper, food packaging paper, and neutral packaging paper.
Kraft paper. Kraft paper is a high-grade packaging paper made from kraft wood pulp, which has a high degree of sizing and is named after its toughness and strength resembling cowhide. Kraft paper is commonly used as the hanging surface and lining of paper boxes, as well as for making files and paper bags that require firmness.
Parchment. Parchment, also known as plant parchment or sulfuric acid paper, is a high-quality chemical pulp paper without sizing. Due to the use of sulfuric acid treatment for sheepskin, it is also known as sulfuric acid paper. Parchment has good moisture resistance, air tightness, oil resistance and mechanical properties. It is a semi transparent high-grade packaging paper with high oil resistance, water resistance, breathability, and high wet strength. Parchment paper for food packaging can be used for the packaging of dairy products, fats, fish, candy Dim sum, tea and other foods.
Paper bag paper. Similar to kraft paper, it is mostly produced from softwood kraft pulp, so the mechanical strength of paper bags is very high, and they are generally used to make packaging bags for cement, pesticides, fertilizers, and other industrial products. To meet the requirements of filling, paper bag paper requires a certain degree of breathability and a large elongation.
Corrugated base paper. Also known as corrugated core paper. It is the raw material paper used to form the corrugated core of corrugated cardboard.
Art paper. Also known as coated printing paper, it is a high-grade printing paper made from raw paper coated with white paint. Mainly used for printing covers and illustrations of high-end books and magazines, color pictures, various exquisite product advertisements, samples, product packaging, trademarks, etc.
Chicken skin paper. Chicken skin paper is a type of flat and thin packaging paper with high gloss and toughness on one side. The production process is similar to that of single sided glossy kraft paper, but due to its lower strength than kraft paper, it is called chicken skin paper.
Food packaging paper. Food packaging paper can be divided into the following three types. The first type of food packaging paper is candy packaging base paper, which is often rolled paper and is printed, waxed, and processed for candy packaging and trademark use. The second type of food packaging paper is ice cream packaging base paper, which is printed, waxed, and diced as ice cream packaging paper. The third type of food packaging paper is ordinary food packaging paper, which is a type of food packaging paper that is not processed with wax and is directly used for packaging imported food.
Cellophane. Cellophane, is a kind of natural regenerated cellulose transparent film, which is made from high-grade bleached sulfite wood pulp through a series of chemical treatments to make a glue solution, and then molded into a film. Cellophane is a kind of advanced packaging material with excellent transparency. Its visible light transmittance reaches 100%. It is soft and even in thickness. It has excellent gloss, printability, masculinity, oil resistance, heat resistance, and no static electricity.
Ordinary packaging cardboard is mainly used for manufacturing and processing into paper boxes, paper tubes, paper barrels, or other packaging products.
Commonly used cardboard includes white cardboard, yellow cardboard, box cardboard, gray cardboard, tea cardboard, standard cardboard, thick cardboard, and other varieties, which are mostly used to package ordinary goods.
White cardboard. White cardboard is a type of white hanging cardboard, which is composed of a surface layer, a core layer, and a bottom. The surface layer of single-sided white paper board is usually made of bleached chemical wood pulp, with a flat surface. The core layer and bottom layer are commonly made of low-grade raw materials such as semi chemical wood pulp, waste pulp, and chemical straw pulp. White cardboard is mainly used for sales packaging and has good printing, processing, and packaging performance.
Carton board. Carton board is a type of cardboard mainly made from chemical straw pulp or waste pulp, which is the surface material for manufacturing products such as corrugated cardboard, solid fiberboard, or cardboard boxes. Mainly brown, with a flat surface, tight fibers, good paper toughness, good pressure and water resistance, and good printing performance.
Standard cardboard. Standard cardboard is a type of packaging cardboard that has undergone calendering treatment and is suitable for producing precision, special molded products, and heavier products. The color is the original fiber color. Cardboard requires a flat surface without warping and a uniform thickness throughout the entire sheet.
Yellow cardboard. The cardboard with a yellow surface and a wide range of uses has a certain strength. It is usually made by using rice straw in caustic soda or lime pulping, with mild beating. The production process is simple, and the cost and product quality requirements are not high. Commonly used for packaging low-cost products.
Processing paper and cardboard
In order to increase the packaging suitability of paper and paperboard, the products obtained by surface coating, impregnation, modification, compounding, and other processing techniques on paper and paperboard are called processed paper.
The main varieties of processing paper are parchment paper, cellophane paper, rust proof paper, fresh-keeping paper, oil proof paper, vacuum aluminized paper; Processing cardboard includes coated cardboard, composite cardboard, corrugated cardboard, honeycomb cardboard, and other varieties.
Coated cardboard. Coated processing paperboard is a type of paperboard that is coated with a layer of paint, chemicals, or a thin film to improve the surface performance and appearance of the paper, enhance its packaging printability and protective performance, and achieve excellent water resistance, oil resistance, moisture resistance, anti-corrosion, and decorative properties.
Composite cardboard. It refers to a composite material formed by combining plastic film or metal foil to enhance certain properties of cardboard, such as heat sealing and high barrier properties.
Corrugated cardboard. A multi-layer cardboard formed by processing corrugated base paper into corrugated shapes and bonding it with cardboard in a certain way. Corrugated cardboard is the most important packaging material for production and transportation packaging.
Honeycomb cardboard. Honeycomb cardboard is made based on the principle of natural honeycomb structure. It is a new type of environmentally friendly and energy-saving material with a sandwich structure that connects corrugated base paper into countless hollow three-dimensional regular hexagons using adhesive bonding method, forming a whole paper core, and bonding the surface paper on both sides.
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