Additives to Enhance Hydrophilicity of PU Foam

Transcription

1 Additives to Enhance Hydrophilicity of PU Foam UTECH 2012 Rüdiger Landers

2 Difference in Hydrophilicity How is it possible to influence the interaction between liquids and foam?

3 Some Applications with Contact Liquid - Foam Barrier foams (baby mattress) Applicators for paints (paint rollers) Sponge foam for body care & household Sealant foams Hydrophilicity Foam in fuel tanks Foam for dypers Hydrophobicity Ink cartridges Intrusion of ceramic slurry into foam Cushions for outdoor / marine applications Medical applications Substrate foam

4 Interaction between Liquids and Foam

5 Influence Factors Reticulation Air flow / closed cell content - Cutting or tearing - Flame treatment - Cell size - Intrinsic property - Presence of thickeners - Intrinsic property - Presence of surfactants Viscosity of the liquid Surface Tension of the liquid (against air) LIQUID Interfacial Tension between liquid and foam - Interaction between foam and liquid - Presence of surfactants Foam Porosity Hydrophilicity/ Hydrophobicity Foam Surface Interfacial Tension between foam and liquid external internal FOAM - Presence of membranes/ reticulation - Roughness of internal surface - Cell size - Interaction between foam and liquid - Presence of surfactants

6 Strategies to Enhance Hydrophilicity Tailoring the Interaction between Foam and Liquid Modification of the polymeric matrix Addition of surface active agents ( Surfactants ) - tailoring polarity - including ionic groups - network density - - into the liquid - into the foam (to be released)

7 Silicone Surfactants Surface Tension: Polyol without stabilizer: 33.5 mn/m Polyol with silicone stabilizer: 21.1 mn/m Siloxan Polyether Normal silicone surfactants for flexible foam are not mobile Special silicone surfactants are required to be released

8 Disadvantages of both Approaches Matrix modifications to increase Interaction between liquid and foam Addition of Surfactants original Swelling Swelling in water Foam after compressing the foam 20 times Liquid Foam Formation

9 Test Methods Absorption Test Droplet test Sink Test Creep Test

10 Hydrophilic Ether Foam 100 pphp Standard polyol (OH number: 47 mg KOH/g) 4.0 pphp water 0.2 pphp TEGOAMIN DMEA 1.0 pphp TEGOSTAB BF pphp KOSMOS 29 x pphp Additive to influence hydrophilicity 48.3 pphp TDI 80 <Index 105> (to be adjusted to keep index constant) - Box foaming - Hand pouring

11 5 pphp Polyvinyl alcohol 30 pphp NOP 20 pphp PPG polyol 25 pphp polyol replaced by hypersoft polyol 10 pphp polyol replaced by hypersoft polyol without 5 pphp Super absorber powder 1 pphp Super absorber powder 5 pphp Agar Matrix Changes Ether Foam Absorption Test reference absorption [g]

12 Addition of Surfactants Ether Foam Absorption Test ORTEGOL HPH 1 ORTEGOL HPH 2 absorption [g] reference without Ortegol HPH 1 (5 pphp) Ortegol HPH 1 (2 pphp) Ortegol HPH 1 (1 pphp) Ortegol HPH 1 (0.5 pphp) Ortegol HPH 2 (1 pphp) Ortegol HPH 1 (0.1 pphp) Alkyl benzene sulfonate (1.5 pphp) C 3499 (1 pphp) BC 6279 (3 pphp) BC 6279 (1 pphp) C 3563 (1 pphp) Ortegol HPH 2 (3 pphp) posttreated with Ortegol HPH 2

13 Disadvantages of Matrix Changes and Addition of Surfactants Additive reference foam, no special additive 1 pphp ORTEGOL HPH 2 25 pphp hypersoft polyol post-treatment of reference foam with ORTEGOL HPH 2 in acetone Swelling in water [change of dimension] 2% 2% 6% 2% foam formation [foam height] 0 3 mm 0 30 mm

14 Hydrophilic Ester Foam - Formulation pphp Standard ester polyol (OH number: 60 mg KOH/g) 4.5 pphp water 1.5 pphp N-Methylmorpholine 1.2 pphp various stabilizers 50.8 pphp TDI 80 <index 100> - Box foaming - Machine pouring

15 1.2 pphp B Ester Foam Absorption Test TEGOSTAB B pphp B pphp B pphp B pphp B 8300 absorption [g]

16 Summary 1) Tailoring the matrix polarity with formulation changes (polyol, ) is possible, problem might be swelling. 2) Special silicone surfactants are highly efficient to enhance wetting of foam by hydrophilic or hydrophobic liquids more or less without swelling. 3) For ether foam special silicone surfactants could be added without affecting the foaming process too much. ORTEGOL HPH1 or HPH2 are candidates of choice. 4) Ester surfactants might promote penetration of liquids, TEGOSTAB B 8301 (for hydrophilic foam) or TEGOSTAB B 8383 (for hydrophobic foam) might be recommended for ester foam. 5) Results depend on test method. 6) Foam structure parameters play an important role (porosity, cell size).