Ultra-thin film type urethane resin for moisture permeable and waterproof materials"SANPRENE H-600"

What is Great about Urethane Resin for Ultra Thin Film Type Moisture Permeable and Waterproof Material "SANPRENE H-600" 


Polyurethane resin solution used to form a moisture permeable and waterproof skin layer

“SANPRENE H-600" is a polyurethane resin solution for synthetic leather skin layer (for dry transfer method) used to form a moisture-permeable and waterproof skin layer on moisture-permeable and waterproof fabrics used for rainwear to prevent rainwater penetration and swelling. 


Thin film can be made while maintaining water resistance

"SANPRENE H-600" developed by our company forms a tough dry film with a tensile strength of approximately 90MPa when cut, which cannot be obtained with conventional polyurethane resin solutions. 

 "SANPRENE H-600" can be made thinner while maintaining its waterproofing properties, enabling a flexible, non-stiff texture and excellent moisture permeability, thereby improving comfort. Furthermore, the amount of resin used can be reduced, leading to weight savings and cost reductions.

"SANPRENE H-600" is a polyurethane resin solution used to form a moisture-permeable and waterproof surface layer. 

Appearance Pale yellow liquid
Viscosity Approx. 70,000 mPa-s (20°C)
Evaporation residue Approx. 20 mass percent 
Solvent Dimethylformamide 

Award-winning examples related to "SANPRENE H-600"
The Kinki Chemical Society 2018 Chemical Technology Award "Development of "SANPRENE H-600", a urethane resin for ultra-thin film-type moisture permeable and waterproof materials". 

The award recognizes outstanding achievements in research and technology related to chemistry that have been clearly identified as having industrial, social, or academic value. In the development of "SANPRENE H-600", the award was given in recognition of not only the design of the composition, but also the establishment of manufacturing technologies such as lowering the viscosity of the coating solution, stabilizing it over time, and achieving ultra-high molecular weight through advanced reaction control, as well as the industrialization of the product. 

About Breathable and Waterproof Materials 

Water permeable waterproof membranes have pathways that allow only water vapor to pass through while preventing water droplets. There are two main types: the microporous membrane type, which has numerous tiny holes, and the non-porous membrane type, which has no holes. 

Microporous membrane type moisture permeable waterproof membrane

The microporous membrane type allows water vapor to dissipate through microscopic holes. The holes allow water vapor to pass through easily, but have the disadvantage of being less waterproof. Therefore, in order to obtain a waterproof effect, it is necessary to use a water-repellent material such as PTFE and add a certain degree of thickness, which causes rainwear to be stiff.

"Non-porous membrane type" waterproof and moisture permeable membrane 

In the non-porous membrane type, there is a component in the membrane that blends with water, through which water vapor escapes from the humid interior to the humid exterior (the image of water vapor soaking into and dissipating from the material). For this reason, polyurethane and other materials that have hydrophilic components and are flexible and easy to strengthen are used. The absence of holes makes it waterproof, but its weakness is that the thicker the membrane, the poorer the moisture permeability. However, if strength can be increased, the material can be made thinner and moisture permeability can be further improved.  

"SANPRENE H-600" is a polyurethane material used for "non-porous membrane type" moisture permeable waterproof membranes. 

Fig. Example of Waterproof Breathable Fabric Structure

Fig. Fabric with polyurethane film laminated to substrate 

Example of Urethane Resin for Ultra Thin Film Type Moisture Permeable and Waterproof Material "SANPRENE H-600" applications 

Breathable waterproof material is a functional material that does not allow water from the outside to pass through, but only water vapor from the inside to escape. 

Examples of Major Applications of Waterproof Breathable Materials


Golf wear 

Ski/snowboard wear, etc.

Performance of Urethane Resin for Ultra Thin Film Type Moisture Permeable and Waterproof Material  "SANPRENE H-600"

The tensile property values, water swelling rate, and moisture absorption/desorption of "SANPRENE H-600" dry film are shown below. 

Tensile property values and water swelling rate of dry membranes 

The following table shows the tensile properties and water swelling rate of "SANPRENE H-600" dry-type membranes.

Tensile property values and water swelling rate of dry membranes
Item Measured value
Tensile strength at cutting
Elongation at cutting
100% Stress MPa 5.6
Water Swelling Rate

Test Method 

The following coating solution was applied to polypropylene (PP) film at a thickness of 1 mm (wet), dried at 20°C for 1 hour and 70°C for 2 hours, and cured at 50°C for 48 hours. The resulting dry film with a thickness of approximately 200 μm (dry) was then peeled off from the PP film and used as a sample. 

<Formulation of coating solution> 

Formulation ratio (mass ratio) 
SANPRENE H-600 : 100 
Methyl ethyl ketone : 50 

Measurement Method of Tensile Properties 

 Measured with a No. 3 dumbbell test piece in accordance with JIS K 6251. 

Method of Measuring Water Swelling Ratio 

Samples were cut into strips 100 mm long and 10 mm wide, and the lengths were measured after immersion in water at 20°C for 30 minutes. Then, the water-swelling ratio was calculated from the following formula. 

Water Swelling Rate % = 100 x (Length of sample after immersion in water mm-100mm)/100mm

Tensile property values and water swelling rate of dry membranes

The following figure shows the moisture absorption and desorption properties of "SANPRENE H-600" dry film with a thickness of approximately 200μm. 

Fig. Moisture absorption and desorption of dry membrane

Test Method

Same as the samples used for the measurement of tensile properties and water swelling rate of dry film.

Method of Moisture Absorption/Desorption Measurement 

Samples were cut into 100 mm squares and placed in a thermostatic chamber at 25°C, 60%R.H. for 3 hours to measure the standard mass. The sample was then placed in a 25°C, 90%R.H. thermostatic chamber for 1 hour, and then in a 25°C, 60%R.H. thermostatic chamber for 1 hour, during which the sample was removed every 15 minutes and its mass was measured during moisture absorption and desorption. 

Moisture absorption/desorption % = 100 x (standard mass of sample - mass of sample when moisture absorption/desorption occurs) / standard mass of sample 

How to use Urethane Resin for Ultra Thin Film Type Moisture Permeable and Waterproof Material  "SANPRENE H-600"

1Preparation of coating solution

Standard formulations are shown below. Uniformly mix them to prepare the coating solution. 

<Standard formulation of surface layer coating solution> 
Formulation ratio (mass ratio) 
SANPRENE H-600 : 100 
Methyl ethyl ketone: 50 

In addition to methyl ethyl ketone, toluene, ethyl acetate, dimethyl formamide, or a mixture of these solvents can be used as a diluting solvent. 

Select the optimum solvent composition by checking the drying speed, swelling caused by the combination with polyurethane resin solution for the adhesive layer (a phenomenon in which the surface skin layer is swollen by the solvent in the adhesive layer coating solution and the release paper grain is not transferred properly), viscosity of the coating solution and coating property, etc. in advance. Add pigments, etc. as necessary. 

 The table below shows the solvent dilution properties of "SANPRENE H-600".

Solvent name Solvent dilution
Methyl ethyl ketone  Can be diluted up to about 2x (mass); if more than 2x, the diluted solution becomes cloudy or separated.
Ethyl acetate 
Dimethylformamide  Almost, can be diluted at any ratio
Isopropyl alcohol Not dilutable


Coat the release paper with the coating solution using a doctor blade, gravure roll, or other coating device. 

The coating amount varies depending on the type and thickness of the base fabric (woven, knitted, nonwoven, etc.) to be laminated, but the standard amount is 100 to 150 g/m2. 


The surface skin layer should be formed by drying in a dryer such as a zone dryer. The drying temperature varies depending on the type of base fabric and the solvent composition of the coating solution, but generally ranges from 100 to 120℃. 

4Lining up with base fabric and curing

The pre-blended coating liquid for the adhesive layer is coated onto the surface skin layer at a predetermined thickness, dried under predetermined conditions, and then laminated to the base fabric with a heat roll at a predetermined temperature. After sufficient curing, the moisture-permeable waterproof fabric is peeled off from the release paper and rolled up. 

 The formulation of the coating solution for the adhesive layer, its application thickness and drying conditions, as well as the appropriate hot roll temperature and curing conditions, vary depending on the polyurethane resin used for the adhesive layer. The optimum conditions should be set according to the polyurethane resin used for the adhesive layer. 

We offer "SANPRENE H-120", a two-component curable polyurethane resin solution for the adhesive layer. 

Fig. Process Diagram of Waterproof Breathable Fabric Production (Example)

Precautions against misuse

When using other resins in combination, check the compatibility with other resins in advance and use them to the extent that there are no problems. 

 ・Equipment such as coating solution preparation tanks and coating equipment should be thoroughly dried before use. If moisture remains in the coating solution, the polyurethane resin in the coating solution will partially solidify and precipitate, forming a coating film with poor surface smoothness. 

Before handling this product, be sure to read the "Safety Data Sheet" (SDS) for this product and its sub-materials (chemicals). The SDS can be obtained here. 

Related Information

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