Printing Applications and Manufacturing Standards for Paper Carrier Bags

Making paper shopping bags by hand is an ancient handicraft. In post-press processing, however, while ordinary printing people generally know something about book binding or paper box creasing and gluing, they may be less familiar with the production process of paper shopping bags. Paper shopping bags fall broadly into two categories: ordinary packaging bags and fine shopping bags. Ordinary packaging bags are produced in a continuous operation on a rotary printing bag-making machine. Their advantage is fast production efficiency; their disadvantage is that the bags are rough and unrefined, so such bags are mostly used for the packaging of ordinary commodities.

As for fine shopping bags, sheets are printed in color, then given PP glazing or hot stamping, after which the bag-making factory produces them by hand or with semi-automatic machines, and finally the handles are threaded and knotted manually to complete the paper bag. Their advantage is that paper bags in any form can be made; their disadvantage is slow production speed. Such shopping bags are mostly used for the packaging of fine goods, as gift bags, or as advertising bags for various commercial activities, and in the end these fine, beautiful paper bags have become convenient take-along shopping bags for ladies out shopping. Characteristics that a shopping bag should have

Eco-friendly and attractive, refined and durable

A shopping bag should first of all be an extension of corporate image and commodity advertising strategy, so in making shopping bags, attention must be paid to being eco-friendly and attractive, refined and durable. Tight structure, no bottom drop-off and no loosened handles: hot-melt adhesive is used on a fully automatic bag-making machine to bond the various parts of the shopping bag into a tightly integrated structure, so the bottom and handles will never come off, unlike conventional post-press processing of paper shopping bags, which uses "white glue" to paste the bag body and then threads and knots the handles by hand, and therefore often suffers from the bottom dropping off or the handles coming loose. Crease-free bag surface, accurate and beautiful bonding: since the shopping bag is made on a fully automatic bag-making machine, the bag surface has no creases; in addition, hot-melt adhesive has strong fixing power and dries quickly, so the bonding is accurate and beautiful. In conventional bag processing, the bag is folded and pasted by hand, so the bag surface has fold lines, and white glue dries slowly and over-application causes glue overflow and slipping, so the bag shape is relatively poor.

Upright cotton rope handle, no punched holes and no knots

Two pieces of heavy kraft paper are used to fix the cotton rope with hot-melt adhesive, and the kraft paper is then fixed to the paper bag, so the shopping bag's handle is "upright" and requires no punched holes, nor does it have protruding knots. With conventional handmade paper bags, the bag body is first punched, then a nylon rope is threaded through and knotted by hand, using the knot to catch on the paper bag, so when carrying items the handle knot easily comes loose, or the rope hole in the paper bag is pulled apart. The overall structure is strengthened to enhance the packaging function: the handle, kraft paper board, paper bag and bag bottom are integrally formed with hot-melt adhesive, so the shopping bag's overall structure is strengthened and can bear items of more than 5 kilograms. With conventionally made paper bags, the handle relies on a nylon rope knot catching on the bag body, and the top flap of the paper bag is not bonded to the bag body, so the load-bearing capacity is weaker.

Design specifications and manufacturing principles for shopping bags: the top edge of the paper bag is always folded inward by 60 mm to strengthen the fixing of the handle. The bottom edge width of the paper bag is 15 mm to strengthen the load-bearing capacity of the bag bottom (the edge width is reduced by 15 mm).

The glued edge of the paper bag is always 30 mm and must be on the right side so that the bag can be glued automatically.

The final artwork for a shopping bag should provide folding marks such as 2 glued-edge lines, 6 top-edge lines and 6 bottom-edge lines to facilitate correct forming of the paper bag. The manufacturing dimensions of a shopping bag must conform to the paper's cutting layout for cost-effectiveness. The paper grain direction must be parallel to the "height" of the paper bag to facilitate paper folding.

Bag-making specifications: paper bag length / 180–350 mm.

Paper bag width / 60–160 mm.

Paper bag height / 270–450 mm.

Paper thickness / about 100–150 lb.

Handle choice / paper rope or cotton rope.

Type S / full-paper quarter-sheet bag

Size / length 18 × width 7 × height 27 cm.

Paper used / 15″×21″.

Grain direction / parallel 31×43.

Type M / chrysanthemum-paper folio bag

Size / length 22 × width 8 × height 30 cm.

Paper used / 17″×25″.

Grain direction / parallel 31×43.

Type L / full-paper folio bag

Size / length 27 × width 10 × height 38 cm.

Paper used / 21″×31″.

Grain direction / parallel 43×31.

Type X / chrysanthemum-paper full-sheet bag

Size / length 32 × width 10 × height 45 cm.

Paper used / 25″×35″.

Grain direction / parallel 25×35.

Type T / full-paper three-panel bag

Size / length 24 × width 10 × height 24 cm.

Paper used / 15″×28″.

Grain direction / parallel 31×43.

Kraft paper / kraft paper has a tough texture and can be distinguished by color into white kraft, yellow kraft, two-tone kraft and other paper types; in terms of paper quality it can further be divided into pure kraft and coated kraft. Basically, kraft paper from 80 to 120 lb is suitable for making all kinds of shopping bags. Coated paper / coated paper is suitable for high-quality color printing, so art shopping bags are often made from 120–150 lb coated paper. Because coated paper has relatively low toughness, PP film glazing is generally used to reinforce its toughness. Art paper / art paper is a vague term, used to describe paper types that have been processed and dyed. Art paper is usually tougher than coated paper and its paper quality is diversified; many 100–150 lb art papers are quite suitable for making shopping bags, but the paper cost is higher. Specialty paper / for example: Nanya synthetic paper, 3M Tyvek paper, pp imitation kraft paper… and so on.

——This article is reprinted from China Packaging Network (pack.cn), original link: http://news.pack.cn/show-362278.html