# R902 Plastic Modifier: Film Anti-Blocking and Opening—Another Path That Does Not Rely on Fluorinated Additives

Fact source: 锎锔-功能助剂1.10.pdf (page numbers refer to the physical pages of the PDF). All quotations and data in this article are reproduced verbatim from the original, with no inferential additions.

There are three actions on a film production line that may seem minor, but cause considerable trouble once completed: winding, stacking, and trimming. During winding, two layers of film come into contact; when a stack is taken off the machine and set down, the top and bottom are pressed together. Trimming is the most difficult to handle—as soon as the blade is drawn through, the interfacial force between the two layers causes them to stick together; when they are pulled apart, it is not a tear but a tug.

Why do films stick together? The manual identifies three overlapping causes:

“Prevent sticking problems in plastic films caused by vacuum adsorption, intermolecular forces, or thermal motion.” (Source: 锎锔-功能助剂1.10.pdf p73)

These are precisely the three issues that anti-blocking additives need to address. The fluorinated route is one option, while R902 takes the route of silicon compounds.

(fluorine-free product)

I. How Blocking Occurs and Where Additives Come into Play

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8Data figure 8

Upper film layer · Bulk regionInterfacial layer · Additive action siteLower film layer · Bulk regionReduce interlayer friction and adhesionInterfacial location of thin-film adhesionCross-sectional schematic (excluding measured peel force and coefficient of friction values)

• Upper film layer · Bulk region
• Interfacial layer · Additive action site
• Lower film layer · Bulk region

When thin films stick together, the essence is interfacial contact. To separate them, either reduce the forces acting between the interfaces or create a layer of physical separation on the surface.

The manual describes the “reduced blocking” aspect as follows:

“Reduced blocking: form microscopic bump-and-valley structures or a lubricating layer on the film surface, reducing interlayer friction and adhesion.” (Source: p73)

Specifically, additives act in three areas:

Reduced blocking

form microscopic bump-and-valley structures or a lubricating layer on the film surface, reducing interlayer friction and adhesion;

Improved processing performance: improve the melt flowability of polyolefin resins (such as PE and PP), reducing die lip buildup;

Enhanced film quality

reduce surface defects (such as crystal points and the sharkskin phenomenon), improving the smoothness and transparency of the film.

The third point is easily underestimated. Crystal points and sharkskin are appearance defects—crystal points are bright spots on the film surface, while sharkskin is the surface pattern left by melt fracture—food and pharmaceutical packaging films and coated films have very low tolerance for such defects. If there are dozens of crystal points in a roll of film, the entire roll is downgraded. Once surface roughness increases, slip and opening performance deteriorate as well. Therefore, anti-blocking and slip have never been two separate matters.

II. Two Directions of Use

The overview paragraph in the manual explains two ways to use R902 in two paragraphs; the methods of use are different.

Direction 1: Add to coating or agricultural film. The manual states:

“When added internally to coating or agricultural film products: it can increase the heat resistance of pigments by 4 to 5 degrees, reduce die-mouth carbon buildup, and reduce pigment precipitation (effective against slight precipitation), improve the dispersibility of pearlescent and fluorescent pigments, and assist water-repellent agents in increasing water repellency.” (Source: p73)

The most practical point in this passage is the 4 to 5 degrees of pigment heat resistance. Pearlescent and fluorescent pigments have low heat-resistance limits and discolor as soon as the processing temperature rises; die-mouth carbon buildup, meanwhile, consumes machine time during material changes and cleaning. Slight precipitation appears as hazy colored spots on the film surface and is especially noticeable on light-colored films.

Direction 2: Add to plastics such as PP, PE, ABS, PS, and PA. The manual states:

“When added internally to products such as PP, PE, ABS, PS, and PA: it can improve product rigidity without changing toughness (generally used as a rigidity- and toughness-enhancing agent). When used together with erucic acid amide, it can be used as an opening slip agent for films such as PE, PP, PA, EVA, and POE.” (Source: p73)

Opening slip concerns something different: film cut edges are prone to sticking together into a “single body” during production, and slitting depends on the knife; if it is done poorly, the entire roll is scrapped. After a slip agent is added, the cut edges separate smoothly, making the rolls received by downstream customers easier to slit and use.

improving product rigidity without changing toughness,

III. Technical Specifications

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III. Technical…

Item	Indicator
Product name	Plastic modifier R902 (fluorine-free product)
Main composition	Silicon compounds
Appearance	White powder
Specific surface area of powder	140±25 ㎡/g (the manual's original formatting is “140 +25㎡/g”, interpreted as a ± value)
Bulk density (approximate value)	Approx. 980 g/l
Moisture content	＜0.8 wt% at 105℃ for 2 hours
pH value	6.2-6.7 in a 4% dispersion
SiO₂ content	Based on the material after ignition, wt% ＞34 (the manual's original wording is “Sio content”)
Loss on ignition	Material dried at 105℃ for 2 hours, after ignition at 1000℃ for 2 hours ＜66 wt%
Addition level	0.5%—5% of the final plastic product
Packaging	25 kg/bag PE double-layer bag
Storage conditions	Store in a cool, dry place; protect from moisture

(Source: 锎锔-功能助剂1.10.pdf p73)

The specified addition amount is a range from 0.5% to 5%, which spans a wide range. Lower-end dosage corresponds to processing-side requirements such as improving melt flowability and reducing carbon buildup at the die lip; higher-end dosage corresponds to the anti-blocking and slip performance of films. Which end of the range to use depends on whether the formulation contains any other surface-treatment components.

The two specifications—white powder and a bulk density of approximately 980 g/l—have direct implications for feeding and metering: The volume is not large, and the selection of the metering screw and hopper must be calculated according to this density; conventional rule-of-thumb values for powders cannot be applied directly.

IV. Applications

The application areas listed in the manual are:

Packaging films

BOPP, CPP, LDPE, and other films for food and pharmaceutical packaging;

Industrial films

agricultural films, protective films, etc.;

Other plastic products

pipes, fibers, sheets, etc.;

Particularly suitable for film production requiring high transparency and high smoothness.

microscopic uneven structures or a lubricating layer

V. Common Questions

Q: What is the relationship between R902 and fluorine-containing additives?

(fluorine-free product)

Q: Is R902 itself a slip agent?

R902 on its own is not equivalent to an opening-and-slip agent. The manual says: when added internally to products such as PP, PE, ABS, PS, and PA, it can increase stiffness and toughness; when combined with erucamide, it can be used as an opening-and-slip agent for films such as PE, PP, PA, EVA, and POE. To achieve opening and slip, the two need to be arranged as a pair in the formulation.

Q: Will adding it to the plastic body make the product brittle?

It leaves toughness unchanged and increases product rigidity (generally used as a stiffening and toughening additive).

Q: How is the 0.5%–5% range determined?

It depends on which end the target falls at. Processing-side requirements—reducing die-head carbon buildup and improving flow—use the lower end of the loading range; film anti-blocking and slip performance use the upper end. Once the direction has been determined, run a gradient of small-scale trials.

Q: Is a 4-to-5-degree increase in heat resistance a small improvement?

These 4 to 5 degrees represent an increase in the pigment’s maximum heat-resistance temperature. The color-change thresholds of pearlescent and fluorescent pigments are already very tight, and in pigment-containing formulations, a few degrees of margin often make the difference between being able to run a high-speed production line and not. The actual achievable speed must be based on the customer’s own pigment heat-resistance data and color-matching system.

Q: Is this the same as another article on this site about R902 external lubrication?

Die-Head Carbon Buildup, the Quietest Cost on the Coating Line

VI. Statement of Facts and Basis

The data in this article come from a single source, 锎锔-功能助剂1.10.pdf, with page numbers indicated alongside the text for item-by-item verification. Key original sentences quoted from the product materials identify their sources in the body text and have not been rewritten. Characters such as “140 +25㎡/g”, “Sio content”, and “Wt•%” are damaged in the manual’s original layout; in this article, they are rendered according to their usual meanings as a specific surface area of 140±25 ㎡/g, SiO₂ content, and wt%, respectively.

One point of definition needs to be clarified: R902 is included in the comprehensive series in the manual. This article does not make determinations regarding discontinued or currently available status, nor does it provide a formulation-level definition or certification conclusion for the claim of being fluorine-free—it is a product positioning statement, not a regulatory conclusion. For use in scenarios subject to compliance requirements, the test report accompanying the batch shall prevail. What was not done: no measured data, such as film peel strength, coefficient of friction, or haze value, have been fabricated; these need to be measured on the customer’s own film types and processes.