Corrugated board is glued by box board and corrugated original paper, which is a composite board used to manufacture corrugated cardboard box. Raw materials of corrugated boardare mostly plant fiber raw materials, although different in types, its chemical composition is mostly cellulose, hemi cellulose, lignin and a small amount of starch, pectin, resin, etc., and cellulose is the primary chemical composition of plant fiber, accounting for more than 50% of all kinds of paper raw materials.
Cellulose is a polymer compound, generated by glucose polymerization, each glucose radical ring contains 3 alcohol hydroxyl groups, so that cellulose molecules and moleculeshave a strong hydrogen bond, cellulose is very easy to absorb water and swelling, the fiber internal cell wall structure becomes relaxed, cohesion decreases.
This is the micro-reason that corrugated carton are sensitive to humidity changes. Therefore, the variety of environmental humidity will have agreat impact on the performance of corrugated board.
2.Corrugated Board Strength Under Different Humidity Conditions
(1) Experimental Equipment
Constant temperature and humidity box, corrugated board cutting device, electronic compression tester, a test equipment used for corrugated board edge pressure strength and adhesion strength, piercing strength tester, used for corrugated board piercing strength.
(2) Experimental Methods
The experimental raw material is AB five-layer corrugated board provided by carton factory, with an average thickness of 8mm. Sampling is conducted according to GB/T450-1979. Test specimen under temperature is 20 ℃, humidity is 20%, 40%, 60% and 80% respectively under the condition of 24h, according to the GB/T 6546-1998 corrugated cardboard marginal pressure strength measurement, GB/T 6548-1998 corrugated cardboard gluing strength measurement and GB/T 2679.7-2005 board puncture strength measuring method.
(3) Experimental Results
Test the edge pressure strength, adhesion strength and puncture strength of corrugated board under different humidity conditions. The experimental data are shown in table1.
(4) Analysis of Result
From the data of table 1, it can be seen that the edge pressure strength and adhesive strength of corrugated board decrease with the increase of environmental humidity; When the relative humidity is 20%~60%, the puncture strength increases with the increase of humidity, and decreases when the relative humidity exceeds 60%. When the relative humidity increased from 20% to 40%, the strength decreased significantly, and the relative humidity decreased by 16.4%. When the relative humidity increased from 60% to 80%, the adhesive strength decreased by 18.5%, and the puncture strength increased by 75% when the relative humidity increased from 20% to 40%.
Environmental Humidity on Corrugated Carton Strength
1. Corrugated Carton Compression Strength Under Different Humidity Conditions
Corrugated box compressive strength is mainly affected by corrugated board edge compression strength and adhesion strength. In different humidity conditions, corrugated board edge compression strength is obviously different, therefore, corrugated box compressive strength is also affected by environmental humidity. The compressive strength of corrugated cartons under different humidity conditions is shown in table 2.
As shown from the data in table 2, the compressive strength of corrugated cartons decreases withthe increase of environmental humidity.
This is because as the rise of environmental humidity, the moisture content of paper board is increase, the cellulose in corrugated board became loose after absorption of moisture, and moisture absorption rate of linerboard and inner linerboard are different, resulting in different rate in the process of the pressure on the deformation, so the compressive strength of corrugated carton decreased as the rise of environmental humidity.
Corrugated cartonno matter in production or in the process of circulation will be affected by the environmental humidity. Therefore, reasonable control in the production, warehouse storage and environmental humidity during transportation, will have a positive impact on the use of corrugated board, carton.
In addition, the production of corrugated board raw materials with moisture, moisture resistance agent has gradually become adeveloping direction to a new type corrugated cardboard box .