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Environmentally friendly raw materials for flexible packaging


Laminated films and foils for flexible packaging need to meet demanding and very specific requirements, particularly when used for food contact or in medical applications. Bayer MaterialScience offers a large range of solutions for this application. The product range covers raw materials like polyisocyanates, polyols and prepolymers for the formulation of adhesives in the flexible packaging area.

Bayer MaterialScience provides raw materials for the formulation of flexible packaging adhesives -> value chain chart.










One-component laminating adhesives
In general, one-component systems are suitable for paper laminates or any porous substrates. Raw materials suitable for this application are moisture-curing isocyanate-terminated prepolymers. 1K polyurethane adhesive formulations can be based on prepolymers of the Desmodur® E series, poly-isocyanates (Desmodur®) or polyester, polyetherester or polyether polyols (Baycoll® AD, AS and Desmophen® BD and BT series).

Two-component laminating adhesives
Any non-porous substrate, particularly transparent and metallized films or metallic foils requires a two-component system. They are the system of choice for all applications – high, medium performance and general pruporse laminates. "High performance bonding" means that the finished adhesive needs to meet specific requirements. This can be obtained by a specific combination of polyester, polyetherester or polyether polyols (Baycoll® AD, AS and the Desmophen® BD and BT series) with polyisocyanates (Desmodur®) and in most cases by the addition of a solvent. The result is an OH-functional prepolymer that is subsequently combined with a suitable polyisocyanate and formulated into the final adhesive. These adhesives are used in applications like food packaging or medical packagings. They might be subject to high mechanical stresses, high temperatures and/or aggressive chemicals like acid food ingredients.

A selection of suitable raw materials for flexible packaging adhesives

Polyisocyanate & prepolymers

Type
Solids in
%
% NCO
on solids
Viscosity
mPas
Characteristics
Desmodur® 44 M, liquid
MDI
polyisocyanate
100
33.6
4,1
(at 40°C)
Crosslinker for polyurethane adhesives
Desmodur®
2460 M
MDI
polyisocyanate
100
33.6
12,0
(at 25°C)
For prepolymers in one- and two component polyurethane adhesives and related applications
Desmodur® CD-L
MDI
polyisocyanate
100
29.0
35
(at 25°C)
For polyurethane adhesives, particularly in food related applications
Desmodur®
N 75 MPA
HDI biuret
75
22.0
250
(at 23°C)
For two-component polyurethane adhesives with high resistance to chemicals and outstanding mechanical properties
Desmodur®
L 75
TDI
Polyisocyanate
75
17.7
1600
(at 23°C)
For two-component polyurethane adhesives with high resistance to chemicals and outstanding mechanical properties
Desmodur®
E 23
MDI Prepolymer
100
15.4
1800
(at 23°C)
For solvent-free, moisture-curing one-component and two-component adhesives

Polyols: polyester-, polyesterether-, polyether



Type
Solids in
%
% OH
on solids
Viscosity
mPas
Characteristics
Baycoll® AD 2047
linear
polyester
polyol
100
1.7
appr. 7000
(at 75°C)
Suitable for many different substrates like metal and films
Baycoll® AD 2055
linear
polyester
polyol
100
1.7
appr. 630
(at 75°C)
Good resistance to hydrolysis, suitable for many different substrates like metal and films
Baycoll® AD 1225
linear
polyester
polyol
100
6.8
appr. 100
(at 75°C)
Good resistance to hydrolysis, suitable for many different substrates like metal and films
Desmophen® 1700
linear
hydroxyl-bearing
polyester
100
1.3
appr. 17500
(at 23°C)
For higher flexibility in Desmophen®/Desmodur® formulations
Desmophen® 2060 BD
linear
polypropylene
ether polyol
100
1.7
310
(at 23°C)
For flexible, low-solvent and solvent-free coatings and adhesives

Polyurethane dispersions

Type
Solids in %
pH
Viscosity
mPas
Characteristics
Dispercoll® U XP 2643
Polyurethane
dispersion
40
7.5
< 1000
(at 23°C)
For systems with low heat sealing temperatures down to room temperature
Dispercoll® U XP 2682
Polyurethane
dispersion
50
7.5
< 1000
(at 23°C)
For systems with low heat sealing temperatures

Crosslinkers for polyurethane dispersions

Type
Solids in %
% NCO
on solids
Viscosity
mPas
Characteristics
Bayhydur® 304
HDI
Polyisocyanate
100
18.2
appr. 4000
(at 23°C)
For waterborne adhesive systems with high quality requirements, easy to emulsify

    UV/EB-curing raw materials:

    Urethane-acrylates and urethane-acrylate dispersions
      Radical polymerization, initiated by UV- or electron-beams, enables the formulation of packaging adhesives with immediate final adhesion. The product lines of Desmolux® (100% solids) and Bayhydrol® UV (polyurethane dispersions) cover raw materials with excellent adhesion to a wide range of packaging substrates combined with good flexibility.

      Type
      Solids
      Viscosity mPas at 23°C
      		Characteristics
      Desmolux® VP LS 2266
      Epoxy-esteracrylate
      100 %
      6500
      		Very high UV-reactivity, elongation at break appr. 8%
      Desmolux® U 100
      Urethane acrylate
      100 %
      7500
      		High UV-reactivity, elongation at break appr. 25%
      Desmolux® XP 2513
      Urethane acrylate
      100 %
      25000
      		High UV-reactivity, elongation at break appr. 30%
      Desmolux® XP 2491
      Urethane acrylate
      80% in Isobornyl- methacrylate
      90000
      		Low UV-reactivity, elongation at break appr. 300%
      Bayhydrol® UV
      VP LS 2348
      Urethane acrylate
      emulsion
      40% in water
      < 100
      		After evaporation of water strong tack, elongation at break <10%
      Bayhydrol® UV
      2689/1 XP
      Urethane acrylate dispersion
      42% in water
      appr. 32
      (DIN 4)
      		After evaporation of water slightly tacky, high UV-reactivity, elongation at break <5%

      Isocyanato-urethane acrylates
        For a high-quality packaging adhesive and in order to enhance adhesion further, isocyanato urethane acrylates can be added to the formulation (dual cure), resulting in specific property profiles.

        Type
        Solids
        % NCO
        on solids
        Viscosity mPas at 23°C
        		Characteristics
        Desmolux® VP LS 2396
        Isocyanato-
        urethane-acrylate
        100%
        7.5
        16000
        		Flexible
        Desmolux® XP 2510
        Isocyanato-
        urethane-acrylate
        91% in Butyl acetate
        7.0
        20000
        		High UV-reactivity

        We recommend to discuss your individual requirements with our experts for technical assistance.
          The products listed represent just a small part of our product range suitable for flexible packaging. Depending on the desired final properties and the nature of the adhesive compound different components can be used. Components can be combined in such a way that particular properties can be fine-tuned to match specific performances. Please find here more detailed product overview. Also, have a look at this presentation for additional information (general aspects, lamination process, product overview, typical problems and their solution).

          Look for more product and application information in these brochures:


          Produktbroschüre Dispersionen
          		Dispersions - Products and Applications
          Produktbroschüre - Isocyanate und Prepolymere
          		Polyisocyanates and Prepolymers: Products and Applications
          Produktbroschüre - UV-Systeme
          		UV-Systems: Products and Applications

          Have a look at our presentation for FEICA, Sept. 2008:
          "New PU-Raw Materials for Adhesives and Sealants without R 40 labeling"


          Please have a look at these most important regulations for adhesives in flexible packaging applications
          Many flexible packaging applications need to comply with specific regional or local regulations. Have a look at these links for the most important regulatory authorities and the relevant regulations.
              FDA
                CFR Title 21 – Food and Drugs
                  § 175.105Adhesives
                  § 177.1390Laminate structures for use at temperatures of 250 deg. F and above
                  § 177.1680 Polyurethane resins
              EU regulations
                  Reg. 178/2002 General principles and requirements of food law
                  Reg. 1935/2004Food contact materials (framework regulation)
                  Dir. 2002/72/ECPlastic materials and articles intended to come into contact with foodstuffs (“plastics directive”)
              Council of Europe
                  ResAP (2004)1 Surface coatings intended to come into contact with food
              Local regulations
                  Germany (BfR)
                      XXVIIICross-linked polyurethanes as adhesive layers



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