In the purchase of biodegradable bags, “thickness” and “price” are the two core indicators that users care about most. Different from traditional plastic bags, due to the particularity of raw material properties and production processes of biodegradable bags, the impact of thickness on price is more significant. Moreover, this relationship is not simply “doubling the thickness means doubling the price”, but the result of the combined effect of multiple factors such as material cost, performance requirements, and market positioning. To understand the relationship between the two, it is necessary to analyze them one by one from three aspects: cost composition, product positioning, and market application.
From the perspective of cost composition, raw material cost is the core factor that affects the price based on thickness. The mainstream raw materials of biodegradable bags are PBAT (polybutylene adipate terephthalate) and PLA (polylactic acid). Among them, PLA is made from renewable resources such as corn starch, and its raw material cost is about 2-3 times that of traditional polyethylene. Although the cost of PBAT is slightly lower, it is also higher than that of ordinary plastics. An increase in thickness means an increase in the amount of raw materials used per unit area: taking the common flat-mouth biodegradable bag as an example, a thin product with a thickness of 0.015mm uses about 15 grams of raw materials per square meter; while a thickened product with a thickness of 0.03mm uses 30 grams of raw materials per square meter, which directly doubles the raw material cost. Moreover, thickened biodegradable bags have higher requirements for raw material purity. Thin products can add a certain proportion of low-cost fillers such as starch and cellulose (usually no more than 20%), while thickened products need to increase the purity of PBAT and PLA (the proportion of fillers must be controlled within 10%) to ensure load-bearing capacity and toughness, which further pushes up the raw material cost. According to industry data statistics, for every 0.01mm increase in thickness, the raw material cost of biodegradable bags increases by an average of 8%-12%, which forms the basis for price differences.
Differences in production processes further amplify the relationship between thickness and price. Thin biodegradable bags (with a thickness of 0.012-0.02mm) can be produced using conventional blown film technology. The equipment has a fast rotation speed, high production efficiency, and stable product yield (usually above 95%). The output per unit time is high, so the labor and equipment costs allocated to each product are low. However, the production difficulty of thickened biodegradable bags (with a thickness of ≥0.025mm) increases significantly: on the one hand, it is necessary to reduce the rotation speed of the blown film machine to ensure sufficient stretching of raw materials and avoid bubbles or uneven thickness, and the production efficiency is only 60%-70% of that of thin bags; on the other hand, the thickened material has a slow cooling speed, which requires additional investment in cooling equipment, and the product inspection standards are more stringent (such as load-bearing tests and tear resistance tests), so the product yield is 5%-8% lower than that of thin bags. Taking a biodegradable bag factory as an example, when producing thin bags with a thickness of 0.015mm, the daily output of a single production line can reach 500,000 pieces; while when producing thickened bags with a thickness of 0.03mm, the daily output is only 280,000 pieces. After allocating labor and equipment costs, the cost per thickened bag is 15%-20% higher than that of thin bags, which further widens the price gap.
Product performance positioning and market demand determine the final pricing logic of thickness and price. Thin biodegradable bags (0.012-0.02mm) are mainly for light-weight scenarios (such as fresh food packaging and small daily necessities storage). These scenarios have low load-bearing requirements (1-3 kg), and users pay more attention to environmental protection and low cost. Therefore, the price is positioned at a civilian level, with an average market price of about 0.1-0.2 yuan per piece. Medium-thickness biodegradable bags (0.02-0.025mm) are suitable for multi-scenario use (such as supermarket shopping and clothing storage), with a load-bearing capacity increased to 3-5 kg. They balance cost-effectiveness and practicality, with a price range of 0.2-0.35 yuan per piece, and are the main force in market sales. Thickened biodegradable bags (0.025-0.05mm) focus on high-strength needs (such as moving and packaging, heavy goods transportation, and industrial storage), with a load-bearing capacity of up to 5-10 kg. Some products also add anti-aging coatings or anti-slip textures, and their performance is close to that of traditional thickened plastic bags. Correspondingly, their prices are higher, usually 0.35-0.8 yuan per piece, mainly for corporate customers or high-end individual users with high durability requirements.
It is worth noting that the relationship between thickness and price is not absolutely linear. When the thickness exceeds 0.05mm, the growth of raw material consumption for biodegradable bags slows down (because overly thick materials tend to have excessive rigidity and are not easy to fold), and the production process needs to be specially adjusted (such as multi-layer co-extrusion). At this time, the rate of price increase will narrow, and it is more determined by product functions (such as waterproof and anti-bacterial) rather than just thickness. In addition, bulk purchasing can partially offset the price difference caused by thickness. For example, when purchasing 100,000 thickened biodegradable bags with a thickness of 0.03mm, the unit price can be reduced by 15%-20% compared with the retail price, while the price reduction range for bulk purchasing of thin bags is only 5%-10%. This also provides users with different needs a space for cost-effective choices.
In conclusion, the thickness and price of biodegradable bags present a “stepwise positive correlation” relationship: an increase in thickness drives up the raw material cost and production process cost, which in turn leads to a price increase, and this correlation is more significant in medium and thin products. When purchasing, users do not need to blindly pursue thick bags, but should choose the appropriate thickness according to the actual use scenarios (such as load-bearing requirements and frequency of use) to find a balance between environmental protection, practicality, and cost. For light-weight scenarios, choose thin bags to control costs; for heavy goods scenarios, choose thickened bags to ensure durability. Only in this way can “value for money” be achieved.
