What Is Corrugated Cardboard

 What is corrugated cardboard?

Corrugated cardboard (or corrugated board, corrugating paperboard), is a multi-layer glued paperboard, consisting at least of a layer of fluted/corrugated paper (wavy) and a layer or more flat linerboard ( or facings). Corrugated cardboard has high mechanical strength and can well withstand collisions and drops during handling. 

The actual performance of corrugated cardboard depends on three factors: quality of corrugated paper, quality of linerboard and the cardboard structure (flute type). 

Corrugated Cardboard

The quality of linerboard can be categorized into K(kraft), A, B, C and, D, among which K or kraft is the best while D the poorest. Similarly, the quality of corrugated paper is also categorized into 4 classes: A, B, C and D, the quality level goes all the way from class A down to the class D. The paper grammage generally ranges from 110g to 350 g per square meter.

What are the corrugated flute types?

Flute Type	Flute Height & Count	Appereance	Characteristics & Applications
A	4.5-5.0mm; 34+/-3 per  length of 30cm	relatively high and sparse flutes	flexible with good cushioning, resistance to high pressure; suitable for fragile and intolerant items, such as glassware, ceramics and plastic toys, etc
B	2.5-3.0mm; 50+/-4 per  length of 30cm	lower and denser flutes	with high compressive strength; suitable for shock-resistant commodities such as beverages and food cans.
C	3.5-4.0mm; 41+/-3 per  length of 30cm	in between A and B	has both rigidity and shock absorption properties; suitable for packing fragile items,  and hard objects that needs to prevent from scratches, etc.
E	1.1-2.0mm; 93+/-6 per  length of 30cm	dense and thin	thinnest and with highest compressive strength & flat surface; good for high-quality printing.

Flute Types of Corrugated Cardboard

Corrugated cardboard are mainly used in the manufacture of cartons, carton sandwiches and other packaging materials for fragile commodities. It is mainly made of earthen straw pulp and waste paper through beating to make raw paperboard similar to yellow paperboard, which is then mechanically processed and rolled into a corrugated shape, and then glued to the cardboard paper with adhesives such as sodium silicate on the surface.

Paper packaging materials

Paper materials have the advantages of low cost, suitable for mass mechanized production, good formability and foldability, good for exquisite printing, recyclable, economical and environmentally friendly, etc. Therefore, various types of paper products have become the most commonly used packaging materials.

1. Kraft paper 

Kraft paper is tough and inexpensive, with good folding and water resistance. It is mostly used to make shopping bags, envelopes, cement bags, etc., as well as food packaging paper.

2. Coated paper 

Coated paper is mainly refined from high-grade wood and cotton fibers materials, and is divided into two types: single-side copper(C1S) and double-side copper(C2S). It is suitable for multi-color register printing, with bright colors and rich gradation changes after printing. It is often used in the production of handbags, business cards, books and magazine covers.

3. Whiteboard paper

Whiteboard paper is hard and thick, has good standing strength, surface strength, folding resistance and printing adaptability, and is suitable for packaging boxes, liners, etc. Usually one side white and the other grey.

4. Cardstock paper

Cardstock is sometimes called pasteboard or cover stock and is often used as a heavy paper option. Card stock is a more durable and much thicker than ordinary printing paper or writing paper. The main difference between cardstock and whiteboard paper is, cardstock is fully made of virgin pulp, it's thicker print or cover paper.

5. Corrugated cardboard

Corrugated paper has the advantages of lightness and firmness, strong load and pressure resistance, shock resistance and moisture resistance, and low cost. Single corrugated cardboard is generally used as a protective layer for product packaging or to make partitions inside a shipping cartons during storage and transportation; 3-ply or 5-ply corrugated cardboard is used to make products' outer packaging cartons; 7-ply corrugated cardboard is mainly used to make packaging boxes for mechanical and electrical products, furniture, motorcycles, and large household appliances.

6. Grey board or chipboard

Grey board is made of waste paper pulp. It's thick, rigid and dark in color. Grey board is not foldable, nor printable, but they are usually used for rigid gift boxes to reinforce them. They are cheap and serves as the main frame of most rigid gift boxes. Grey board is generally not viewable to consumers as they are covered by printed paper wraps.

Rigid Gift Boxes Made of Greyboard

Cost Estimation for Commonly-used Packaging Materials

① Paper cost: 

Calculated based on the number of products packaged per sheet of paper. For example, the size of copy paper is generally of 105cm * 75cm. If the unit price of such paper is RMB 0.12/sheet and a piece of such paper can pack 5 products, then the packaging cost of paper each product is RMB 0.024. (All cost hereinafter are in China's currency RMB)

② Bubble wrap cost: 

Generally calculated by weight, that is, the weight of the bubble wrap needed to package each product  times market price.

③ Polyfoam cost:  

A. The calculation method for manually making the required shape or size: length (m) * width (m) * height (m) * 350 ~ 450. The coefficient differs with regions, for example, 350 in Quanzhou, Fujian, but 450 in Huangyan, Zhejiang  province. 

B. The calculation method of the mold set-up: mold fee + grammage of the polyfoam * 0.017/gram, (0.017/gram is the price coefficient, and there will be a certain rise or fall with the change of market prices)

④ Sponge cost: 

Generally, the price of a sponge with a thickness of 1cm is 3.5/m². The material cost is calculated according to the thickness and square of the sponge required for packaging products. The price of sponges with other thicknesses is calculated proportionally. For example, the price of a sponge with a thickness of 2cm is about 3.5 * 2 =7.0/m². ⑤ Plastic bags, OPP bags: price = length (m) * width (m) * 2S * market price of the plastic bag, where S is the thickness of the plastic bag, for example, the size of a 4-wire plastic bag is 30 * 25 cm , At the time the market material price was 10800/ton, the price of plastic bags was 0.3 * 0.25 * 2 * 0.00004 * 10800 = 0.065.

⑥ Packaging boxes: 

Ordinary brown inner box price = (length + width + 7 )/100 * (width + height + 4 )/100 * unit price, where the unit of length, width, and height is cm. The white box calculation method is similar to this. Simple calculation method for color box: Expanded area of ​​color box (m²) * coefficient (3.8 ~ 4 ), if laminated, the coefficient is 4.8. Calculation method of unfolding area: [(length + width) * 2 + 3 ]/100 * 〔( width * 2 + height) + 2 ]/100, among them, the length, width and height are cm. For example, the size of an uncoated color box is 7 * 6 * 16 cm, then the unfolded area is 〔( 7 + 6) * 2 + 3 〕/100 * 〔( 6 * 2 + 16) + 2 〕/100 = 0.087 m². The approximate price of the color box is 0.087 * 4 = 0.35. 

Note: This estimation method can only be used for smaller color boxes.

The basic cost of a general corrugated color box mainly includes: paper cost, corrugated cost, printing cost, glazing, calendering, laminating cost, pasting salary and taxes, etc. There are generally two paper specifications: standard 78.7 * 109 cm and large standard 89 * 119 cm.

The calculation method of the price of the color-printed gift boxes is to calculate the number of boxes that can be made according to the actual unfolded size of the color box, and calculate the number of boxes that can be made according to the standard (or large) size, thereby obtaining the cost of paper for a single box, plus corrugation, printing, Expenses for glazing, calendering, laminating and taxes. General pricing standard is:  RMB 0.10/color for CMYK offset printing, 0.30/m² for coating, is 0.60/m² for calendering, RMB 0.60 ~ 0.80/ m² for laminating and corrugated is RMB 1.50 ~ 2.00/m².

Generally, the cost evaluation of gift boxes requires additional plate-making and die-cutting fee. The normal-size plate-making fee is RMB 300~600, and the die-cutting fee is 150. The calculation method of color card is similar to this. 

⑦ PVC box or PVC tube cost:

 the cost is calculated by weight, currently it is generally calculated at 0.025/g. For example, if a PVC box weighs 20 grams, the cost is about RMB 0.50.

⑧ Shrink film: 

The cost is about length (m) * width (m) * thickness (m) * 15000/ton (subject to change over time). 

The cost estimation methods introduced above are not static and subject to change with market. Be sure to jointly consider the region difference, time, labor price, and material fluctuations, etc. 

Advantages and Disadvantages of UV Coating

After UV coating treatment, the appearance effect of paper packaging products can be largely improved, make the printing quality thick and full, gloss and rich, improve the decoration effect of paper products, and can significantly improve the folding and chemical resistance, and improve its performance , To reduce the loss of products in the process of transportation and storage. For products with high requirements for moisture resistance (such as electrical appliances, etc.), the paper packaging products are treated with UV coating to improve the moisture resistance of the packaging.

Advantages of UV coating

1. No environmental pollution, no solvent volatilization, which is safe and environmentally friendly.

2. Fast drying speed and high production efficiency. Since the photo-curing reaction can be completed in an instant, the UV varnish can be directly stacked or entered into the next process after printing and curing, which speeds up the production process and improves production efficiency.

3. Not limited by the types of substrates, not only can be used to polish the surface of paper, aluminum, plastic materials, but also can be used to polish the surface of polymer plates, furniture, metal materials, wireless materials, etc.

4. Save space and energy, because the UV varnish does not need auxiliary equipment such as drying tunnels for ordinary oily varnish during the curing process, and the volume of the UV curing machine is small, and the effective utilization rate is high, so it greatly saves space and energy. , To reduce the investment in early equipment.

5. Good quality, the printed matter surface after UV coating is smooth and bright, without warping, wrinkling, blistering, etc., and the surface hardness is high, abrasion resistance, not easy to scratch, and chemical corrosion resistance is good. Compared with the laminating film, the cost is only about 1/4-1/3 of the laminating film.

Disadvantages of UV coating

1. The first is the security issue. At present, the active diluents used in UV varnishes have certain volatility or irritation, which still pollutes the environment. The water-based UV varnish that is currently being researched and developed uses water or thickener instead of active diluent to solve the problem of volatility and irritation. It is an ideal environmentally friendly product.

2. Next is the smell problem. Now it is gradually developing in the direction of low odor. At present, the packaging products of UV glazing have not been fully recognized by the International Food and Drug Administration, and they cannot be in direct contact with food. Therefore, it is necessary to improve the working conditions and environment, improve the drying effect, and obtain thorough curing, thereby reducing the odor.

3. The third is the adhesion problem on the oxidative polymerization ink. Not only there are problems such as odor and low gloss, but also difficult to attach glue. Nowadays, double coating is often used to improve the quality of UV coating, but it also increases the cost. Therefore, it is necessary to improve the adaptability of UV varnish and ink.

4. Finally, there is the issue of cost reduction. Although the cost has dropped a lot, it is cheaper than the cost of BOPP composite film composite. But in China, there are many types of UV varnishes and their performance is different. So the price difference is big. In general, the cost is still too high, and it is necessary to further reduce the cost of varnish, coating costs and equipment operating costs.

The influence of UV coating on the color of printed matter

Prints with UV glazing sometimes show yellowing. There are two main reasons: one is that the UV glazing oil itself turns yellow; the other is that the glazing oil is only cured on the surface of the printed matter during the glazing process. The inside is not completely cured.

The yellowing of the glazing oil is related to the certain yellowness of the oligomers and reactive diluents used, so colorless oligomers and reactive diluents should be used to prepare the glazing oil. In addition, the influence of photoinitiators is also great. Some photoinitiators will cause the system to turn yellow after curing, such as benzoin dimethyl ether. Therefore, avoid using such photoinitiators to prepare varnishes.

During the glazing process, when the interior of the glazing oil is not fully cured, the glazing oil diluent inside will gradually be absorbed by the ink and paper, and at the same time it will have an effect on the binder in the ink, causing the loss of grease. The pigment is not sufficiently protected and the pigment particles are free. At this time, the smoothness of the surface of the paper coating and the ink layer will be reduced. The rough surface will diffusely reflect the light, so that some white components are added to the color, which increases the brightness and decreases the saturation, giving people a feeling of yellowing and lightening of the color. Therefore, the curing speed of UV varnish should be increased or an efficient UV curing light source should be selected. In addition, the use of water-based UV varnish can avoid the chemical effect of the thinner ink layer and the paper coating, and can avoid the yellowing of the printed matter.

Common Knowledge of Packaging Boxes

Material commonly used for gift boxes

(1) Paper:  coated paper, corrugated board, kraft paper, grey board and specialty paper, etc. 

(2) Metal: alloy, tinplate, tin foil, aluminum foil, etc. 

(3) Plastic: PC material, PVC material, PET material, PE material. 

(4) Wood: plywood, bamboo, raw wood. 

(5) Leather: natural leather, artificial leather (synthetic leather, PU). 

(6) Fabric: non-woven fabric, cotton fabric, pure polyester, seersucker, flannel. 

Processing techniques

Hot stamping, laser, thermal transfer, heat transfer, direct jet printing, pad printing, silk screen printing

 Shape

Square, heart-shaped, cylindrical, irregular shape. 

Printing

(1) Silk screen printing: Screen printing is a printing technique where a mesh is used to transfer ink onto a substrate, except in areas made impermeable to the ink by a blocking stencil. One of the most pronounced advantages of this technique is that: it can be applied to not only flat surfaces, but also on curved, spherical, and concave-convex substrates.

(2) Offset printing: Offset printing is maybe the most common printing technique used in packaging. The inked image is transferred(offset) from a plate to a rubber blanket and then to the printing surface. And in most cases, CMYK 4-color printing is sufficient...

For direct-injection printing, usually paper-based materials are not suitable for direct-injection printing, and the cost performance is too low. Unless it is the kind of high value-added will use direct printing. Plastic PE and PET materials cannot be used for direct printing. Wooden gift boxes can be printed as far as the material itself is concerned, but some oily-treated ones are not suitable for digital direct injection technology. When printing leather, you usually need to use professional leather UV ink. The price of this ink is much higher than that of common UV inks. So in terms of cost, it is higher than ordinary products. Non-woven fabrics, pure polyester, seersucker, and flannel are not suitable for digital direct jet printing. The heat transfer is involved before and after digital direct jet printing. Fabrics of these materials are not suitable for heat transfer. 

Market brief

The current market demand for gift boxes presents a demand for personalized customization. For example, some enterprises, public institutions and companies, when they celebrate holidays or hold major events, print the company's name, event content and other themes on the packages of their gifts. In addition, the current young generation will print group photos, banquet themes and other content on the gift boxes during marriages, children's wedding banquets, and birthdays. With the growing scale of the manufacturing industry, the demand for its derivative packaging industry is now becoming more mature. Presents a broad development space and market prospects.

Paper Stock Glossary

Uncoated Paper

There are a variety of coating finishes, and specialized uncoated papers, but paper stock is either coated or uncoated. All paper actually falls into one of these two categories.

Uncoated paper has a non-glare surface and is absorbent. It has nothing covering the natural fibers and easily soaks up ink. Uncoated paper can be textured, for example, a linen finish, but it can also be very smooth, like printer or copy paper. Uncoated paper is the easiest to write on. Uncoated paper is generally used for things like: stationery and standard envelopes, inexpensive flyers, newsletters and a final product you can write on, etc.

Coated Paper

Coated paper has been covered with a hardened clay material so that it will better display text and images with sharper detail and denser color. The coating can be a non-shiny matte, dull, gloss and cast coated (a mirror-finish high gloss), spanning the range from non to super glossy. Paper can be coated on one or both sides. Paper coated on one side is often used for low-cost postcards. Coated paper is more difficult to write on, especially with pencils or ballpoint pens. booklet printing exampleCoated paper is great for: brochures, catalogs, postcards, packaging and a product that you won't be writing on, etc.

What is C2S?

C2S is describing paper that is clay coated (glossy) on both sides. It generally refers to paper that is 8pt and above. (This should not be confused with a gloss coating that is applied to sheets after they are printed, i.e., a post-printing treatment.)

What is C1S?

Similarly, C1S refers to a paper stock that is coated only on one side (versus C2S where the paper is coated on both sides). As the backside is completely un-coated, it suits for applications where a lot of writing is intended on that side.