爽滑开口剂:薄膜收卷不粘连、开口即开,母粒一加效率上来

塑料知识科普 发布时间: 2026-09-14 1523 阅读

A roll of PE film that was just wound up in the workshop looked fine before the end of the shift, but the next day, no matter how they tried on the machine, they couldn’t open it. Two layers were stuck together like a sheet of metal. The operator had to pick at it with a bamboo stick or blow on it with an air gun, and it took half a day to ruin a roll. The packaging line was even more troublesome; the friction coefficient wouldn’t go down, so the filling line got stuck at three hundred packs per minute and couldn’t go any faster. When this batch of material was sent to the customer, they just said, 'We can’t open it,' and returned it.

Film sticking and difficulty in opening are 80% related to using the wrong lubricant and opening agent. This article talks about how to choose a film lubricant: the differences between erucamide and oleamide, how to reduce the friction coefficient, so that packaging line speed can be increased.

First, present a quick reference table of smooth-opening agents, clearly listing mainstream varieties, key parameters, typical products, and addition ranges.

systemRepresentative varietyKey Parameters / FeaturesTypical productsAdd ratio
Fatty amideOleamideFast migration, quick effect, slightly less long-lastingPE film, injection molding release500-1500 ppm
Fatty amideErucamideLong-lasting, low friction, heat-resistant, non-yellowingBOPP/CPP High-Speed Packaging Film500-2000 ppm
Masterbatch openerSilica-basedPhysically rough surface, auxiliary openingPE/PP Blown Film0.1%-0.5%
Smooth masterbatchAmide Concentrate MasterbatchWell dispersed, easy to measureBlown Film / Cast Film0.5%-2.0%
Composite systemErucamide Slip AgentSmooth and easy to openhigh-speed packaging film0.1%-0.3%

Note: The above is the general industry range; films are measured in ppm (1000 ppm = 0.1%). The specific grade and friction coefficient are subject to the manufacturer's TDS and actual measurements; excessive amounts may cause frosting.

The film rolls stick together in a sheet, it's not the material sticking, it's that the surface is too 'rough'.

First, let's clarify a misunderstanding: when two layers of film stick together, it's not that the plastic itself has become sticky; it's that the friction between the layers is too high and they are stuck too tightly. PE and PP films, just after being blown, have surfaces that are smooth and flat. When the layers stick together perfectly without any air in between, rolling them up and pressing them overnight turns them into a solid sheet of metal that can't be separated at all.

There are two approaches to solving this. One is to make the surface of the film smoother—by adding a slip agent (such as erucamide or oleamide), which will gradually migrate to the surface of the film, forming an invisible lubricating layer that reduces the coefficient of friction; the other is to make the surface of the film slightly rougher—by adding an antiblocking agent (such as ultrafine silica), which creates microscopic bumps on the film surface, leaving air gaps between the layers so that they naturally do not stick. The two methods are often used together.

Ningbo Kelong New Materials Co., Ltd. has long been engaged in the sale of various plastic raw materials and additives, with stable supplies of PE and PP film materials, as well as slip agents and masterbatches. For slip agents, the main types are fatty acid amides—oleamide works quickly, erucamide has long-lasting effects, and when combined with silica-based masterbatches, the film is both smooth and easy to open. Kelong New Materials recommends combinations based on the customer's film type and packaging line speed, provides samples at the kilogram level, and includes comparative data on friction coefficients.

Film sticking doesn’t cause two rolls of material to stick together, it affects the production capacity of the packaging line.

Figure 1 Schematic of lubricant migrating to the film surface to form a lubricating layer

What the lubricant does is run to the surface of the membrane and lay down an invisible lubricating film.

Explain the mechanism in simple terms. A slip agent is a restless small molecule; when added to plastic, it doesn’t want to stay inside and gradually migrates to the surface. Once on the surface, it forms an ultra-thin lubrication layer outside the film, creating a layer of oil between film and film, and between the film and the machine contact surface, naturally reducing friction. This is why the friction coefficient goes down.

Don't mix up these two types of amides. Oleamide has a smaller molecular weight, migrates quickly, and its coefficient of friction drops into place two to three days after the film is blown. However, over time it slowly evaporates or gets rubbed off, and the coefficient of friction rises again. It is suitable for situations where quick effects are needed. Erucamide has a slightly larger molecular weight, migrates slowly, and isn't as slippery in the first few days after being blown, but it stays more stable, keeping the long-term coefficient of friction low. BOPP high-speed packaging lines prefer it. In industry experience, after adding erucamide to BOPP, packaging speeds can reach 500-800 packs per minute, and the coefficient of friction can be pressed below 0.2.

Adding too much doesn't work either. If the slip agent is overused, too much will crystallize on the surface, which is commonly called 'blooming'—a layer of white powder appears on the film surface, causing haziness and affecting printing and heat sealing. Therefore, the addition amount should be kept in the range of several hundred to two thousand ppm, and not based on intuition. Also, adding this small amount directly into the material can easily lead to uneven mixing. It is recommended to buy pre-dispersed slip masterbatch and mix it in according to the proportion; this ensures stable dispersion and consistent friction coefficient for each batch of film.

Oleamide works quickly but has a short duration, while erucamide heats slowly but lasts long; don’t use them the other way around.

The packaging line speed can't go up; the problem might just be that tiny fraction in the friction coefficient.

This section is about accounting for costs. Why do manufacturers buy slip-opening agents? The loss scenarios are very straightforward: first, after the film is rolled up, it sticks together, operators have to peel it sheet by sheet, resulting in high scrap rates and entire rolls being wasted; second, the packaging line cannot run fast, the coefficient of friction is high, bags get stuck on the machine and don’t slide, and the filling speed is stuck at 300 packages, wasting capacity; third, frosting and fogging occur, leaving white powder on the film surface, which cannot be printed over by customers, leading to complaints and returns.

The amount of slip agent added seems small—just a few hundred to two thousand ppm in the film—but it directly determines whether the packaging line can run fast. According to industry-standard cost calculations, PE film material costs seven to eight thousand yuan per ton, and erucamide is priced at dozens of yuan per kilogram in industrial use. Adding 0.1% only adds a few to several dozen yuan to the cost per ton, but if the packaging line can produce one to two hundred more packages per minute, the extra daily output is enough to buy a year's supply of slip agent.

Where it saves: Friction coefficient goes down, packaging line speed goes up, and unit time output increases. Where it stabilizes: The film does not stick or frost, and the yield from startup to winder is stable. Where it is flexible: For quick effect, use oleamide; for long-lasting effect, use erucamide, and choose according to your own packaging rhythm.

Here’s an example using the industry-standard approach: 1 ton of LDPE packaging film costs about 8,500 yuan per ton, plus 0.1% erucamide (around 40 yuan per kilogram), which amounts to about 40 yuan per ton for the additive. This 40 yuan reduces the friction coefficient from 0.4 to about 0.2, increasing the packaging line speed from 300 packages per minute to 500 packages per minute. The extra output in just one day more than covers this 40 yuan.

Cost itemNot added / added too littleAdd 0.1% erucamideDifference Explanation
Additive costZeroAbout 40 yuan/tonCalculated at about 40 yuan/kg for amide, 0.1%
Coefficient of Friction (COF)About 0.4 astringentAbout 0.2 or lessHigh-speed packaging requirement ≤ 0.2
Verbal expressionThe roll is prone to stickingOpens as soon as it is openedSignificant reduction in film waste rate
Packaging line speedAbout 300 packs/minUp to over 500 packs/minCapacity directly steps up
ComprehensiveSaved money on additives, reduced production capacitySmall investment for faster line speedSettling the bill shows that checking the line speed is more cost-effective

Note: The above is a sample account based on industry market trends; unit prices fluctuate with the market, and actual prices should be based on current quotations. Actual determination should be based on the current quotation and the coefficient of friction from the sample. Not sure whether it's oleamide or erucamide, or how much to add? Send the film type and packaging line speed, and I can help you match the grade and calculate this line speed account.

As for buying ready-made slip-opening masterbatch modified materials, it's still better to use PE resin and add it yourself. Buying masterbatch is convenient, as the dosing and dispersion are already taken care of; however, according to the common industry cost calculations, the extrusion processing fee for one ton of modified pellets, added on top of the raw material, is about 1,000-1,500 yuan, packaging fee is 100-250 yuan, and pipe, sales, and financial costs are about 5%-10%, plus profit. By purchasing resin and adding slip-opening masterbatch yourself, you can save this layer of markup.

Comparison itemBuy modified pellets that are super smooth to mixPE resin smooth opening masterbatch self-prepared
material costIncluding extrusion processing fees, packaging, marketing expenses, and profitThe base price of resin compounded with masterbatch is usually lower (industry common phrasing)
FlexibilitySmoothness is fixed, choose the gradeAdjust the amount of masterbatch according to the film speed requirements
Minimum order quantityMinimum order: one tonResin charged per ton, masterbatch compensated per bag
Delivery timeSubject to supplier schedulingGeneral materials are available immediately; adjustment of ratio is quick.
compliant dataThe supplier gives the reportSelf-controlled formula, retained friction coefficient data
Suitable for whomSmall dosage, no mixing conditionsLarge quantity, many types of films, has film blowing lines

The boundaries also need to be clarified: lubricants are migration-type additives, so when used on films that require printing, corona treatment, or coating, caution is needed. The lubricant layer may affect printing adhesion and should be adjusted according to printing requirements. For food contact films, compliant grades must be selected. In these cases, don't just chase slipperiness; first, coordinate the requirements with downstream processes. Otherwise, even if the film is slippery, problems with printing and heat sealing will be even more troublesome.

When too much lubricant is added, white powder appears on the surface; saving on the opening fee ends up costing the appearance.

Smooth opening is not only used for PE film, but also for BOPP, CPP, and blow-molded parts

Whenever talking about smooth opening, PE blown film comes to mind. In fact, any plastic that forms films or rolls is prone to sticking. Which films and which items need a smooth opening? The table below categorizes them.

CategoryTypical scenarioAddition rangeEffectPrecautions
LDPE blown filmPackaging film, agricultural film500-2000 ppmReduced friction, easy to openPay attention to the frost cap
LLDPE Stretch FilmStretch film, cling film500-1500 ppmSmooth and non-stickyChoose erucic acid for high viscosity requirements
BOPP filmHigh-speed printing packaging film500-1500 ppmLine speed above 500 packs/minPay attention to adhesion on the printed surface
CPP casting filmHeat-seal packaging film500-2000 ppmRoll up without stickingUsed with an opening agent
PP filmStationery/Food Packaging500-2000 ppmReduce COFChoose high-temperature resistant type for high-temperature processing
PE injection molded partsShell, turnover box0.2%-1.0%Easy demolding, smooth surfaceExcessive effect on spray painting
EVA filmInsulation film, shoe sole material0.1%-0.5%Smooth and non-stickPay attention to coordination with foaming
PE Repackaging FilmChemical bags, bulk bags0.1%-0.3%Easy to open, bags fold easilyHigh wear resistance required

This table only provides direction; the specific amount should be determined according to film thickness and line speed during sampling. Ningbo Kelon New Materials Co., Ltd. always has stock of PE and PP film materials, as well as erucamide, oleamide, and slip masterbatches. For high-speed packaging customers, we recommend erucamide combined with slip agents according to line speed, while for customers who need quick results, we recommend oleamide. During the sampling stage, we provide kilogram-level samples and comparison data of friction coefficients. Unsure about film sticking or line speed issues? Send us the film type, thickness, and packaging line speed, and we’ll first help you check the direction.

Only when the membrane can open can the machine operate; when the machine operates quickly, costs can be spread thinly.

The packaging line is stuck at three hundred packages; changing the lubricant will double the speed.

Take a common example from a packaging factory (scenario example, not a specific client). A factory in East China that makes food packaging films, the film blows well and the opening is okay, but it gets stuck on the filling line—the friction coefficient is too high, and the bags can't slide on the machine. No matter how the line speed is adjusted, it's around three hundred bags, and the client is urging to increase the speed.

Ningbo Kelong New Materials Co., Ltd. changed their original oleamide into erucamide with a small amount of silica masterbatch. In the first couple of days after blowing, the friction coefficient didn’t decrease that quickly. After three days, the friction coefficient stabilized at 0.18. The packaging line immediately reached over 500 bags, and they didn’t stick to the bags.

Where the changes are: First, the line speed jumped from over 300 to over 500, and the single-shift output increased significantly; second, the film no longer sticks to the bags, saving labor for operators who tear the bags; third, there is no frost spraying, and the printing adhesion is not affected. The premise is that they are making packaging film for non-printed surfaces; if the printed surface requirements are high, the ratio will have to be readjusted.

This boundary needs to be clarified: lubricants are not a universal speed-enhancing miracle. If the film itself is too thick or sticky, or if there are design problems with the filling equipment fixtures, lubricants alone won't solve the issue; adjustments must also be made in the equipment and process. For films that require high standards in printing, corona treatment, or coating, adding too much lubricant can actually cause problems, so it needs to be determined together with downstream processes.

Reducing the friction coefficient by a few decimal points comes at the cost of the entire packaging line's productivity.

Opens immediately, friction coefficient data speaks for itself

At the end, provide a quick selection reference chart, and match it with your own membrane.

Your membrane/partThink about this firstRecommended directionWhen will you stop choosing like this?
Want quick resultsIt will start sliding a few days after blowingOleamideDon't use it for long-term effect
high-speed packaging lineLine speed over 500 packagesErucamideTest the adhesion of the printed surface first
Roll stickingThe coating sticks like an iron plateErucic acid silica openingExcessive amounts will cause frosting
Transparent printing filmCannot affect printingLow precipitation type, add lessDon't add ordinary amides recklessly
Injection molding demoldingMold sticking and tearing0.2%-1% smoothPay attention to the adhesion of the painted parts
Repackaging thick filmDurable and easy-to-fold bagCompound smooth systemToo thin, not suitable

Several details commonly asked by film factories

Q: How much lubricant is generally suitable for films? A: Usually, films contain 500-2000 ppm, that is 0.05%-0.2%. Injection-molded parts use a bit more, around 0.2%-1%. Use less for thin films and more for thick films. Start testing the friction coefficient from 1000 ppm and adjust slightly. For small amounts, it is recommended to add in masterbatch form for uniform dispersion.

Q: What is the difference between erucamide and oleamide? A: Oleamide migrates quickly and takes effect in two to three days, but its friction coefficient increases again if left for a long time; erucamide migrates slowly and is not as slippery immediately after blowing, but its friction coefficient remains low after a few days, and it is heat-resistant and does not yellow. Use oleamide for quick effect, and use erucamide for long-lasting high speed; don’t mix them up.

Q: If it still sticks after adding a slip agent, or if there is white powder on the film surface, what should be checked first? A: If it still sticks, check whether the migration time is insufficient or if the amount of slip agent is insufficient, and then add more nucleating agent; if there is white powder, it is bloom, indicating an overdose, so reduce the amount. If that doesn't work, check whether the masterbatch is dispersed evenly and whether it interacts negatively with other nucleating additives.

The packaging line can only move if the film can be opened.

The film needs to be opened, and the line speed needs to be increased, so first reduce the friction coefficient.

Ningbo Kolon New Materials Co., Ltd. has long been engaged in the sale of PE and PP film raw materials and slip agents, with stable supply of erucamide, oleamide, and masterbatch slip agents. Whether you are producing BOPP high-speed packaging films and need to increase line speed, or making PE blown films and need to solve sticking issues, you can tell us the film type, thickness, and packaging line speed, and we will recommend a suitable slip system based on the working conditions.

This article talks about smooth opening, and another one in the same series about deodorizing and moisture-absorbing agents discusses how recycled materials remove odor and reduce VOCs. The two articles are used together for manufacturers making recycled films. The series is still being updated, so manufacturers making films should not miss the deodorizing article.

Statement: The brands, trademarks, and product names mentioned in this article belong to their respective original manufacturers. This article is a third-party material selection knowledge sharing. The grade, parameters, prices, dosage, certifications, and application cases mentioned herein are for reference only, and the specifics should be based on the latest official information and batch test reports from the respective manufacturers. This article does not constitute any purchasing or investment advice, and readers bear the risks if they act on this information.

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