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Date：2026-09-30Can you actually stop shade net mould? Yes, but only one route works: build the antimicrobial into the resin. A spray on the surface holds for a short while at best. Both are polyolefin, and both stay clear of mould only when the protection sits inside the tape or the film rather than on it. Pre-mix iHeir-ECO plastic antimicrobial agent at 0.3%-0.5% on PE/PP resin at the tape line, or iHeir-IPL inorganic plastic antimicrobial agent at 0.8%-1% for pale or clear film. This article covers both dosing points, the figures and the selection rule.
1. Where the mould on shade nets and film comes from
Shade nets and film are both polyolefin products. A shade net is woven from high-density polyethylene tape, and film is blown from PE resin. Polyolefin carries no nutrient a mould can live on, so the growth is never in the plastic itself. It sits on what the surface collects: dust, soil, pollen, oil, and the organic residue that comes in with regrind.
Two situations go wrong most often. A net taken down from the frame and rolled up damp has no airflow in the core of the roll, and spots and odour appear within days. Film is thinner and judged on light transmission, so surface spots cut the light and the buyer sees them at the same time. Correcting it later in the warehouse with airflow or a spray only pushes the risk to the week before delivery.
The read is simple. Spots sitting on the surface deposit that lift off when rubbed point to storage. Spots that run into the tape and the film, visible on a torn cross-section, mean the base material carries no protection. A spray or dip does not hold on polyolefin either: low surface energy stops the agent keying in, and rain and repeated winding take it off.
2. The two dosing points at a glance
The table lists the product form, the stage, what is treated, the product, the figures and the points to watch. It is written to serve as the first draft of a process card.
| Product form | Stage | Treated part | Product | Figures | Points to watch |
|---|---|---|---|---|---|
| Shade net (HDPE woven) | Tape and masterbatch line | Resin for tape or monofilament | iHeir-ECO plastic antimicrobial agent | 0.3%-0.5% on PE/PP resin | Pre-mix with pellets or make a masterbatch first; heat stable to 240 degrees, avoid above 320 |
| Agricultural film (blown PE) | Film blowing (finished roll) | Blow-film resin | iHeir-ECO or iHeir-IPL inorganic plastic antimicrobial agent | ECO 0.3%-0.5%; IPL 0.8%-1% on resin | Film is thinner, so masterbatch first to avoid agglomerates that fog the film |
| Pale or clear parts | As above | High-clarity or pale resin | iHeir-IPL inorganic plastic antimicrobial agent | 0.8%-1% on resin | Inorganic type, low colour shift, holds above 380 degrees; antimicrobial rate 99.99% or better |
| Finished-goods store | Roll storage | Rolls and packing | Humidity control only | Keep the store below 60% relative humidity | Off the floor, away from the wall, air gaps between rolls, first in first out |
| Export loading | Full container | In-container climate | Humidity control only | Set by box type and voyage | Rolls take up moisture fast; skip in-container control and the first two stages are wasted |
| Retained sample check | Finished rolls and batch sample | Finished roll | Test to the contract scope | Keep one sample per batch | Hold at 28 degrees and 85% humidity for 7 days and read the surface and the cross-section |
Six rows, one conclusion: the tape stage protects the yarn, the film stage protects the film, and the store and the container hold what the first two built.
3. The tape stage: getting the agent into a shade net
A shade net gets one chance: dose the agent into the resin before the tape is extruded. iHeir-ECO plastic antimicrobial agent goes in at 0.3%-0.5% on PE/PP resin, pre-mixed with the pellets. Its melting point is 56-58 degrees and it is heat stable to 240 degrees, so keep the barrel below the limit and avoid running above 320 degrees.
Three things to settle before the line starts. First, the figure is on total resin weight, not finished weight, so a change in the regrind ratio means recalculating. Second, nets with a high regrind share belong at the top of the range: regrind brings in organic residue and moisture that feed mould, and it carries more heat history. Third, dispersion is the whole game. Powder added straight can agglomerate, and an agglomerate is a spot with no protection. Make an antimicrobial masterbatch first, pre-disperse in a matching carrier, then dose at the equivalent loading.
4. The film stage: why blown film needs masterbatch first
Agricultural film is blown and leaves the line as a finished roll. It is thinner than a net, commonly 0.008 to 0.15 millimetres, and light transmission is the headline figure. Powder fed straight into the hopper causes three problems: uneven dispersion that leaves black specks, haze that costs transmission, and local stress points that tear the bubble. At this stage the agent must go in as masterbatch.
For pale film, clear film and greenhouse film judged on clarity, use iHeir-IPL inorganic plastic antimicrobial agent at 0.8%-1% on resin: low colour shift, holds above 380 degrees, and a smaller effect on transmission than an organic type. For thick black film or mulch film where transmission is not the point, iHeir-ECO at 0.3%-0.5% costs less, provided the temperature limit is respected.
5. Choosing between ECO and IPL, then holding the store
The two products divide cleanly. iHeir-ECO plastic antimicrobial agent is the general grade: 0.3%-0.5% on PE/PP, 0.5%-1.0% on PVC, melting point 56-58 degrees, heat stable to 240 degrees, avoid above 320, a good fit for dark parts and volume lines. iHeir-IPL inorganic plastic antimicrobial agent is inorganic: 0.8%-1%, antimicrobial rate 99.99% or better, holds above 380 degrees, and fits pale and clear parts and hotter lines. Three questions decide it: clarity and colour shift, processing temperature, cost.
Once the two dosing points are right, the store still has to be held. Keep the store below 60% relative humidity, load rolls off the floor and clear of the wall, leave air gaps between rolls, run first in first out, and never stage a pending batch against an outside wall. A full container needs humidity control sized to the box type and the voyage. On acceptance: a fresh sample passing does not mean the stacked goods will. Hold one sample per batch at 28 degrees and 85% humidity for 7 days and read the surface and the cross-section.
6. Questions that come up
Can a shade net be sprayed instead? Not as the main route. Polyolefin has low surface energy, so a sprayed agent does not key in, and sun, rain and repeated winding take it off. Make a masterbatch and dose at the tape line.
Does a net made from regrind need more? Yes. Regrind brings in the organic residue and moisture that feed mould and it carries a longer heat history, so choose the temperature-tolerant option and dose at the top of the range. Masterbatch first: far cheaper than a rework.
Will the treatment change how much light the film passes? Not if the right product is chosen. Clear film takes the inorganic iHeir-IPL, which is fine in particle size and low in colour shift. Trouble usually comes from coarse powder and poor dispersion. Take a small sample through transmission and appearance checks before the full batch.
The two dosing points are the tape and masterbatch stage and the blown-film stage, and both come down to making an antimicrobial masterbatch from iHeir-ECO at 0.3%-0.5% on PE/PP or iHeir-IPL at 0.8%-1%, with the store and the container holding the result. Samples and TDS sheets are available, and we are glad to run a trial on your own line.
