FAQ

This page lists the most frequently asked questions by customers.
If the answer to your question is not listed here,feel free to contact Mitsubishi Chemical.
Also, before implementing any solutions listed here,
you must read and agree to abide by the conditions listed in "Read this Section First" section

Basic Introduction

What is Soarnol™?
A

Soarnol™ is the trade name of ethylene-vinyl alcohol copolymer (EVOH) produced by Mitsubishi Chemical Co., Ltd. Soarnol™ can be used for multilayer film, sheet, bottle, tube, pipe and so on combined with polyethylene, polypropylene, polyamide, polyester, etc. By using Soarnol™, those articles shows excellent gas, solvent and aroma barrier properties and are widely applicable to packages for food, medical, cosmetic, agrochemical, etc.

What is a feature of Soarnol™?
A

Gas barrier properties, chemical resistances, oil and solvent resistances, high transparency, weather-resistance, aroma barrier properties, good printability, high luster, low environmental burden.

What is a production method of Soarnol™?
A

Soarnol™ is produced by a saponification of poly (ethylene-vinyl acetate) which is co-polymerization of ethylene and vinyl acetate monomer.

What is a chemical structure of Soarnol™?
A

Soarnol™ is the random co-polymer of ethylene and vinyl alcohol.

What is a shape of Soarnol™?
A

Soarnol™ is provided as cylindrical pellet shape.

Does Soarnol™ contain any lubricant?
A

Yes, but also non-lubricated grades are available.

What is a meaning of “MFR”?
A

“MFR” stands for “Melt Flow Rate” and it indicate a flowability of a resin. High MFR value means low melt viscosity.

What is a regulatory status of Soarnol™
A

Soarnol™ complies with various food packaging regulation including Ministry of Health and Welfare Announcement No.370(1959) and Its Latest Amendment No.18(1994), Voluntary Standards for Food Contact Substances and Polymers (JHOSPA), U.S.A. FDA 21, C.F.R. §177.1360, Commission Regulation (EU)No. 10/2011 and its amendments, etc. For more information, please contact us.

Grades

How to select Soarnol™ grade?
A

Soarnol™ grade is selected by required barrier property and processing method. For example, low ethylene content grade (e.g. 29 mol%) has better barrier property than that of high ethylene content grade (e.g. 44 mol%) under ambient humidity condition. On the other hands, melting temperature of high ethylene grade is low compare to that of low ethylene content grade and this makes processing easier with low processing temperature. MFR (Melt flow rate) is other factor for selection. Choose suitable grade depends on your processing condition.

Is Soarnol™ film commercially available?
A

No, we only sell Soarnol™ resin as pellet. Please contact us if you would like to purchase Soarnol™ film.

Is Soarnol™ solution commercially available?
A

Yes, we have Soarnol™ solution. Please contact us if you would like to purchase Soarnol™ solution.

Basic properties, barrier properties

How to handle Soarnol™?
A

Soarnol™ is highly hygroscopic material same as polyamides. Please store remaining material in moisture proof bag. If Soarnol™ absorb moisture, please dry it until moisture content becomes lower than 0.3wt%. Please refer drying condition to other technical note.

How is a transparency of Soarnol™ film?
A

Soarnol™ film has very high transparency.

Does a barrier property of Soarnol™ depend on humidity?
A

Yes, a barrier property of Soarnol™ getting lower under high humidity condition. Usually, Soarnol™ is used in a multilayer structure combined with other material which has a moisture barrier property.

How to decide Soarnol™ thickness?
A

First of all, please decide packaging style, shelf life, allowance of maximum oxygen ingress and mechanical properties. From those requirements, Soarnol™ grade and its thickness are decided.

Does a barrier property of Soarnol™ depend on its thickness?
A

Yes. It is inversely proportional. A thicker Soarnol™ becomes a better its barrier property.

Processing, film forming

What is processing conditions of Soarnol™?
A

Single screw extruder with a screw L/D=24~30, CR=3~3.5 is recommended. Standard temperature setting is 190~230 ˚C. To avoid thermal degradation, a temperature must not be higher than 250 ˚C. For more detail, please refer “processing technique” section.

What is a recommendation of screw dimension?
A

Please avoid using a screw for polyamide resin which has rapid compression section. A number of pitch of compression section should be longer than 4 but it depends on L/D and compression ratio. More troubles could happen if a number of pitch in compression section is 1~3 especially high rpm extruder. Recommended screw design is; feeding section 30~40, compression section 20~25, and metering section 35~50 in total 100 pitches.

What kind of equipment is required for processing?
A

To make a multilayer structure, at least, two extruders are necessary (one is for Soarnol™ and the other for base material). Use additional extruder for adhesive resin if required.

Is special equipment required to process Soarnol™?
A

No, not necessarily. But to avoid troubles during processing, please consider “less residual part”, “screw design for no residual material”, “proper extruder capacity for no remaining material”, and “plating of melt path”.

What is a suitable adhesive resin for Soarnol™?
A

Many resin suppliers have adhesive resins for EVOH. Please contact these supplier or us for more detail.

How is a heat sealability of Soarnol™?
A

A melting temperature of Soarnol™ is higher than that of other resin used as heat seal layer. So normally, Soarnol™ is not used as heat seal layer.

Does a barrier property of Soarnol™
become lower after boil or retort treatment?
A

It is possible to reduce a deterioration of barrier property by adjusting conditions. After such treatments, a temporal deterioration of barrier property or appearance such as whitening may happen. In such a case, special grade is recommended.

How is a procedure of purging before disassembling?
A

After finish processing, please purge by using LDPE with MFR=1 immediately.

Trouble shooting

How to solve bubbling of Soarnol™ layer?
A

Please check following points;

  • 1.If Soarnol™ absorbs moisture, dry it under 90~110 ˚C by using air circulation or hopper dryer.
  • 2.If processing temperature becomes higher than 240 ˚C, please reduce cylinder and die temperature.
  • 3.Inappropriate screw design
  • 4.Unsuitable processing conditions

If bubbling is still happened even after checking these points, please contact us.

Why small gels are observed during processing?
A
  • 1. Inadequate mixing due to too short screw or low output even if using large size extruder
  • 2. Thermally degraded EVOH due to high processing temperature or long residual time
  • 3. Too low processing temperature
How to reduce a neck-in
A

EVOH tend to have larger neck-in compare to polyethylene. Please check following points;

  • 1. Make an air gap as narrow as possible
  • 2. Reduce die temperature
  • 3. Control a balance between output and line speed