Understand the characteristics of adhesives to grasp market conditions

Adhesives are important auxiliary materials in the paper product industry. They are used in almost every kind of paper products and have a major impact on the quality and cost of paper products. This article will describe the application of adhesives and market conditions in the paper industry according to the category of paper products.

Corrugated board processing adhesives

Corrugated board processing is the largest amount of adhesive in the packaging industry. Most of the adhesives currently used are self-made thermosetting starch adhesives. There are also a few manufacturers with insufficient equipment capacity or using cold corrugation molding technology using synthetic resin or oxidized starch binders.

Heat-curing starch adhesives are self-adhesives made by paperboard manufacturers using starch, caustic soda and borax, which are used to promote adhesiveness of adhesives by high temperature to achieve cardboard bonding.

Starch can be extracted from corn, wheat, rice, potatoes, tapioca, sago, peas and even bananas. Corn starch is the most widely used type of starch in the paper products industry. Earlier, some large foreign-funded enterprises in South China used imported cassava starch to make paste, and the ready-made has been gradually replaced by corn starch.

In recent years, with the advent of new types of high-speed wire and cable equipment that can automatically adjust the amount of paste, the use of wheat starch, which has a low cost and a low gelatinization temperature, is increasingly used. Potato starch and other special starches are mainly used for the bonding of top paper in heavy duty cardboard.

As the continuous improvement of corrugated board line speed, better and better base paper performance, and the quality requirements of adhesives have also changed, the main trends are as follows:
The solid content of adhesives is getting higher and higher;
The initial tack time is accelerated;
Low viscosity;
The gelatinization temperature drops;
Widespread use of paste additives.

Corrugated veneer with adhesive

The amount of adhesive used in corrugated veneers is second only to the corrugated board processing technology. At present, there are three types of calyx base, synthetic resin and starch adhesive on the market.

The silicate also called water glass, its adhesive strength is still acceptable, but there are major defects such as slow drying speed, easy efflorescence, easy to absorb moisture and damage to the carton performance, and it was banned by the national foreign trade department in 1986. .

Synthetic resin adhesive is made by adding polyvinyl alcohol to water, dissolving and stirring, and blending with polyvinyl acetate emulsion. Due to the scarcity of materials, high cost, and high energy consumption, its market share is rapidly declining. In stark contrast to this, starch adhesives quickly occupied the market due to its many advantages such as fast initial adhesion, firm bonding, good water resistance, low cost, and environmental protection. It can be said that, in the foreseeable future several decades, unless there is newer material appearing, water glass will completely withdraw from the market, and the starch adhesive will occupy most of the market share. Synthetic resin will only become an inevitable trend for the development of the adhesive market.

Starch adhesive is the most ideal adhesive. It is made of starch as the main raw material and is mixed with other auxiliary materials. It has many advantages such as fast initial adhesion, firm adhesion, good water resistance, low cost, and environmental protection. The preparation method of the starch binder is an oxidation method, which is characterized in that the starch is oxidized by an oxidant such as hydrogen peroxide, sodium hypochlorite, etc. to degrade it and then gelatinized. However, what is slightly lacking is that the PH value reaches about 12, which has a certain corrosive effect on human skin.

With the continuous deepening of people's understanding of starch binders, the surface coating with starch adhesives presents two distinctly different trends. One is a low-solids, low-price adhesive with a solids content of less than 10%, a price of about 500 yuan/ton, and a slow drying speed. It is suitable for poor paper quality and uses a manual single-side or low-speed coating machine. Covered factory use. However, its disadvantages are also very obvious. Due to the low solid content, in order to ensure the bonding quality, the amount of glue is generally large, so the drying after coating is slow, and cardboard softness, warping and the like are prone to occur. Therefore, this product is limited to the use of some low-end products in China; the other is a high-solid-content, high-priced adhesive with a solids content of over 18% and a price of 700-900 yuan per ton. Its characteristics are excellent adhesion, fast drying speed, small amount of glue, and high hardness of the cardboard after covering, without bending. It is suitable for use in factories where the quality of the base paper is good and the product quality is high.

In the Pearl River Delta and some of the Yangtze River Delta where the packaging industry is developed, due to the large number of packaging manufacturers and the developed traffic, the glue is generally purchased directly from professional adhesive manufacturers. This avoids the tedious process of formulating glue and the resulting instability. In other parts of the country, due to the decentralized packaging companies, and the small scale, basically the use of raw materials purchased to prepare their own way.

Paste box adhesive

Paste cartridges are used for the combined molding of paper (box) boxes with adhesives. The usual bonding sites are cardboard side strips, and a few also include bottom flap bonding. At present, there are numerous types of binders used in the industry for adhesives in the industry, and the price difference is very different. There can be targeted selection when purchasing, so as to avoid wasting costs.

At present, white latex is the most widely used glue in the carton bonding process and is generally used for the adhesion of surface coatings (except UV coating) or plain carton without any treatment on the surface. For the carton without any treatment on the surface, the price of white latex used in the hand-bonding process has been as low as RMB 2,000/ton, and the machine adhesion is due to the higher requirements on the initial adhesion and drying speed of the glue, and the price is more than RMB 5,000/ton. Above white latex. At present, a new type of rubber powder has appeared on the market. The cost of glue for machine gluing has dropped to about 2,500 yuan/ton, while the cost for hand-glued glue is even lower to 1,600 yuan/ton, and the effect is better than 5,000 yuan/ton. emulsion. Cartons with gloss sticks are made of white latex at a price of RMB 8,000/ton or more, and are mostly hand-bonded.

Among the many adhesives, the hot-melt adhesive has the shortest drying time, and hot-melt adhesives should be used for the adhesive forming process that requires instantaneous drying and curing. Hot-melt adhesives are particularly suitable for bonding processes between plastic foams or EPE materials and paper. They not only dry quickly but also have a very strong bond. Hot melt adhesives have a wide range of applications and can be used for bonding paper products of any material and surface treatment process, and are also suitable for manual and machine bonding processes. However, the disadvantage of hot-melt adhesives is that the cost is too high. Generally, the price per ton is more than 10,000 yuan, and it must be heated and melted when used.

The special UV box glue box glue is suitable for the paper products with UV varnish on the surface, and its adhesive needs special attention. To be on the safe side, the first use of base oil, and then UV glazing, and finally the use of special UV box glue box glue adhesive method. Hot melt adhesive bonding can also be used. Special coating box glue box glue is suitable for paper products with surface treated by coating. Hot-melt adhesives can also be used for bonding paper-coated paper products. The price of special UV box glue box glue and box glue box glue box are all above 10,000 yuan / ton.

Cardboard veneer adhesive

Gift boxes, albums, photo albums, paper stationery, paper display stands, greeting cards, and other types of cartridges. After the die-cut coated paper color surface and die-cutting cardboard are pasted and combined, the process is currently applied. Most of the adhesives used are white latex and hot melt adhesives. Because the coated paper is difficult to infiltrate and has strong tensile resistance during the wrapping process, the initial adhesion, solid content and permeability of the glue are required to be very high. At present, the price of white latex used is generally around 5,000 yuan/ton, while the hot melt adhesive is up to 10,000 yuan/ton. Hot-melt adhesives are generally used in cases where one side of the adhesive surface is subjected to UV coating or a lamination process.

Paper tubes, paper corners, paper pallets and adhesives for paper furniture

In the past, due to the limitation of drying speed and adhesive strength, the bonding of paper tubes, paper protection corners and paper pallets basically used synthetic resin adhesives, and the price was generally between 4000-6000 yuan/ton. With the continuous advancement of starch adhesive technology, many starch adhesives newly launched on the market have the same drying speed and adhesive strength as synthetic resin adhesives, while the cost is about RMB 2,000/ton, and thus gradually become starchy. The adhesive is replaced.

Coating adhesive

At present, most of the adhesive products used in the market are solvent-based polyurethane adhesives. In view of the harmful effects of solvents on human bodies, there are potential fire hazards during use. Some manufacturers have developed environmentally friendly, non-flammable, non-toxic, and widely adaptable waterborne environments. Polyurethane adhesives. However, its adhesive strength is lower than the solvent type, the drying speed is slow, the energy consumption and the cost are high, and the development prospect is not optimistic. Recently, foreign companies have also produced solvent-free polyurethane adhesive products. Solvent-free polyurethanes are environmentally friendly products in the true sense of the word. They have strong peeling power, low energy consumption, and a wide range of applications. Therefore, they must be rapidly promoted in the market.

With the increasing environmental protection concepts of people and the increasingly fierce competition in the paper products industry, adhesives in the paper products industry have seen a clear trend of change. In other words, green adhesives, low cost, fast initial viscosity, and firm adhesive starch binders will occupy a greater proportion in various paper product technologies, and the market share of white latex will further shrink, while hot melt adhesives and UV adhesive cartridges Special glues, such as glues and coated glues, will be limited to their exclusive use.

Source: Corrugated boxes