吸管材料怎么选?粘模反复出现,脱模剂救不了本

应用领域 发布时间: 2026-09-12 4058 阅读

The straw sticks to the mold as soon as you sip, and the release agent keeps being sprayed nonstop. The temperature resistance and demolding are not matched, and the inlet parts get dirtier the more you spray.

The mold sticking keeps happening repeatedly, and the release agent can't save the situation.

A water cup straw is an 'inlet bent part': soft, heat-resistant, and bite-resistant. The material should be soft, heat-resistant, and bite-resistant—conclusion first: food-grade SEBS-based TPE is mainstream for water cup straws; silicone remains for boiling in high-temperature water.

The biggest problem with cup straws: repeated sticking during molding, and release agents can't save the situation. Repeated sticking, release agents are useless—sticking occurs at the molding lines of the straw.

The straw of the water cup is a food-grade component: sticking to the mold and deformation are both problems. Choosing the right material ensures stable drinking — it's a food-grade component, don't skimp on material costs.

The hot water nozzle still bites, why use food-grade TPE

Reasons for using TPE for cup straws: flexible, heat-resistant, bite-resistant, and efficient—these four combined make it suitable for straws.

Softness is key: comfortable at the entrance. Softness testing is included in acceptance — if it becomes hard, it's a problem.

Temperature resistance cannot be compromised: hot water inlet. Temperature resistance testing should be included in the acceptance—if it deforms, that's a problem.

Entrance, hot water, biting—what to look at in each of the three stages

Inlet operating condition: contact at the inlet. Soft data needs to be checked—if it hardens, that's a problem.

Hot water condition: hot water inlet. Temperature resistance data must be verified—deformation equals a problem.

Biting condition: children biting. Bite resistance data must be tested—cracking is a problem.

Food-grade TPE vs PP, which one to choose for straws

DimensionFood-grade TPEPP
SoftGoodhard
Temperature resistantCan be doneGood
Bite-resistantCan dohard
Texturesofthard
CostMedium-highLow
PurposeHoserigid tube

Table Reading: PP is cheap but hard; TPE is soft and has a good texture—TPE for soft tubes, PP for hard tubes.

Choose by tube type: rigid tube PP, flexible tube TPE.

Doesn't soften when boiled, doesn't split when bitten, check these four items during inspection

PhenomenonReasonCountermeasure
Sticking moldHigh mold temperatureLower mold temperature
Sticking moldThe filling is too softAdjust hardness
Sticking moldSmall draft angleChange the slope
Sticking moldInsufficient coolingAdd cooling

Form reading method: When bonding the mold, first lower the mold temperature and material temperature, check the venting and ejection; don't expect to spray mold release agent— the straw is thin and soft, and if the parameters aren't right, the more you spray, the messier it gets.

Mold sticking is the forming line of the straw.

Mold release agent is resisted hard, the inlet parts get dirtier the more they are used

Pitfall 1: Stubbornly using release agent. Spraying release agent once can cover several pieces, yet marks still remain on the surface — the root cause is temperature and cooling time, so the parameter settings need to be adjusted.

Pitfall 2: Bite resistance leakage test. Cracking — bite resistance test is a must.

Pitfall 3: Softness falsely labeled. Hard — softness should be accepted according to actual measurement.

Temperature-resistant, soft, easy to demold — check before making the tube

Three questions: What is the water temperature, what test is used for bite resistance, and what is the certification number. One check: actual measurements during use—three questions and one check, the supplier's details are clear.

Mold sticking verification must be done first: mold temperature, material temperature, and cooling time are listed on a card and checked machine by machine. First check for mold sticking, then discuss the price—mold sticking is the forming line of the straw.

Making sample retention a habit: retain samples from each batch, and retest softness and temperature resistance by batch. When changing materials for a batch, compare first before scaling up—the more stable the batch, the fewer the customer complaints.

Sticking to the mold, softening, cracking: a fault comparison table

PhenomenonReasonCountermeasure
Sticking moldIncorrect parameterAdjust parameters
TransformationInsufficient temperature resistanceChange to heat-resistant material
CrackingInsufficient bite resistanceSwitch to high-tear material
OdorAdditive precipitationChange to low precipitation material
UnverifiedCertificate missingNuclear Certification

Baby straw Shore A 30-40, feels like a pacifier—soft but not collapsing. Too hard and it pokes the mouth, too soft and it's hard to suck; bite-resistant, can be gnawed without cracking, and tested with hot water to see that it doesn’t deform at high temperatures.

If the straw turns white and cracks after a week of biting, it's not because the baby is too rough, but because the anti-bending formula is not effective. If the bending radius is less than 4 times the wire diameter, the anti-bending will fail; when sticking to the mold, don't rely on release agents to block it hard, you need to adjust the mold temperature and the cooling window.

Hot water test: Soak in boiling water for 30 minutes, check for deformation, stickiness, and unusual odor. For food contact, follow the report; conduct a blind taste test for softness, with stricter requirements for maternal and infant items.

Silicone straws are soft but three times more expensive and difficult to mass-produce. TPE is seventy percent as soft, with half the price. Food-grade TPE passes LFGB; PVC straws contain phthalates, while TPE has no phthalates and requires no vulcanization, so choose the latter for baby mouthpieces.

Straws deform and become sticky when exposed to hot water, and moms in the group directly called it out. Stickiness occurs because low-molecular-weight substances migrate to the surface, which is more pronounced at high temperatures; choose a high-temperature resistant, low-migration formula, and after a 7-day test sample, it won't stick.

Straws go into the mouth every day and are used with hot drinks, so TPE food grade needs to be heat-resistant, bite-resistant, and low in leaching; too soft and it collapses, too hard and it hurts the mouth.

Hot drinks should not melt or separate; choose food-grade temperature-resistant TPE that passes LFGB, does not become soft or flattened when soaked in hot water, does not leave deep marks when bitten, and does not crack at the bent tube.

The straw is the inlet component, and the migration of color masterbatch and additives is most critical. Low-exudation formulations do not turn white during trial production; each batch is tested by soaking in hot water to check appearance and migration, and if it does not crack when bent, it is released.

Straw finishing acceptance: Temperature resistant without softening, no bite marks, and migration are to be checked with each batch. Samples from each batch are kept to test appearance and migration after soaking in hot water, and bent straws should not crack; when changing material for a batch, first conduct a small batch suction test, pass LFGB, and then release.

Cologne customer case: Insufficient rebound not up to standard, followed by acceptance after odor testing

A modified material application factory in Zhengzhou had issues with insufficient rebound of water cup straws, and the performance of functional parts did not meet standards. Cologne coordinated on-site follow-up and production debugging until the yield stabilized, rebound recovered, and odor level met the customer's acceptance standards. During production follow-up and debugging, the rebound was locked before mass production — for rebound issues, first look at the formulation, then the parameters.

Summary

When selecting a straw for a water cup, check for mold sticking first, then test for softness. If mold sticking repeatedly occurs, release agents won't help; mold sticking is a result of the molding line.

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