SANPRENE LQ-258

1 of 9 products in this brand
SANPRENE LQ-258 is used for resin of artificial leather & synthetic leather-Top layer for moisture-permeable & waterproofing fabrics (resulting film has the excellent moisture permeability).

Polymer Name: Polyurethane (TDI-based)

Chemical Family: Polyurethanes (PU), Thermoplastic Polyurethanes (TPU)

Compatible Substrates & Surfaces: Textiles

Technical Data Sheet

Knowde Enhanced TDS

Identification & Functionality

CASE Ingredients Functions

Features & Benefits

Polyurethane Solutions for Wet-Process Leather and Fabric Coating

Research and development of synthetic leather and poromeric leather as alternatives to natural leather has been ongoing for many years. High breathability, a smooth or suede-like unique appearance or unique tactile property depending on the leather, which natural leather originally has, have been pursued.
We provide a variety of polyurethane solutions for wet processes that produce poromeric and synthetic leather. These solutions differ in compositions, physical properties of dry films, viscosity and tactile properties, and the appropriate solutions can be selected according to the application. We also provide polyurethane solutions for dry-process leather and fabric coating. These typically include: manufacturing dry-process synthetic leather; processing for surface finishing of smooth poromeric leather, wet-process synthetic leather, natural split leather and PVC leather; and coating of waterproof moisture permeable fabric and waterproof fabric.

Features
Hydrolysis resistance, Hardness

Applications & Uses

Compatible Substrates & Surfaces
Plastics & Elastomers End Uses
Application Methods

1. Selection of Product
On the basis of the application and tactile properties, product names of polyurethane resin solutions for wet processes are shown below.

Application Tactile Property *
End
Product
Leather Type
and Layer
 
Shoes Impregnated layer
of poromeric leather
Standard
  • *There are three classifications of tactile properties: softness represents leather which can withstand a 100% modulus of 4.9 MPaꞏs or lower; hardness represents leather which can withstand a 100% modulus of 7.8 MPaꞏs or higher; and standard tactile property represents leather between 4.9 MPaꞏs and 7.8 MPaꞏs.
  • Normally, the lower the 100% modulus, the softer the tactile property of the leather. In order to obtain the standard tactile property, mix products with different 100% modulus values. It should be noted that when mixed, some products may become a turbid white color or separate because of poor compatibility. Please check compatibility in advance. When mixed, products differing in composition, such as polyester-type solution and polyether-type solution, may separate.
  • To form an impregnated layer and a microporous layer, use products with the same resin composition as much as possible. For example, if polyester-type solution is used to form an impregnated layer, and polyether-type solution is used to form a microporous layer, the layer tends to peel.

2. Method to Prepare Coating Solution
The coating solution for the wet process is normally prepared by mixing diluent (DMF),
wet-coagulation accelerator (surfactant), coagulation core agent (e.g. cellulose powder), toner (coloring agent that has pigment dispersed over polyurethane resin solution) and other agents, with polyurethane resin solution for the wet process.
Diluent Usually, keeping the evaporated residue of the coating solution within the range of 7 - 18 wt %, mix the amount of DMF necessary to optimize the coating viscosity. Figure 1 on the next page shows the relationship between viscosity and the evaporated residue of SANPRENE LQ products diluted with DMF. Wet-Coagulation Accelerator (surfactant) Use one or more of the surfactants listed below. Mix 0 - 5 wt % of surfactant with the coating solution. Unless wet-coagulation accelerator is mixed in, a porous wet film may not form.

Product Name Active Ingredient wt % Ionicity Performance
SANMORIN OT-70 * 70 Anionic Coagulation rate: high Form of cell: vertically long
IONET S-80 * 100 Nonionic Coagulation rate: medium Form of cell: globular
NEWPOL LB-1800X * 100 Nonionic Coagulation rate: medium Form of cell: globular

* Sanyo Chemical products

Coagulation Core Agent (cellulose powder)
When coagulation core agent is mixed with microporous-layer coating solution, cells are made uniform to form a microporous layer of superior surface flatness. Usually, 0 - 5 wt % of coagulation core agent is mixed with the coating solution. As the additive amount of the coagulation core agent is higher, the strength of the microporous layer tends to be lower. The additive amount of the coagulation core agent may be judged from its relationship to physical properties such as tensile strength and the peeling strength of the microporous layer. Cellulose powders include KC FLOCK produced by Nippon Paper Industries Co., Ltd.

Toner For the wet process, a wet film of superior color development is obtained by using toner containing a medium that has the same composition as the polyurethane resin solution. Particularly when this product is used for poromeric suede production, the appearance of the leather depends greatly on the color development of the toner. When mixing, select a toner that has excellent color development. Usually, 0 - 5 wt % of toner is mixed with the coating solution, and in the case of poromeric suede, 5 - 15 wt %.

Others
Coagulation of the coating solution for a microporous layer is facilitated and the time required to form a film is shortened in the solution, when the proper quantity of water is added to the solution. However, when polyether-type polyurethane resin solution for wet processes is used as a coating solution, water should not be generally added to the resin solution because the resin solution has a high coagulation rate. Otherwise, the addition of water may cause problems such as poor
appearance which includes stripes on the surface of the microporous layer during coating processes, and lowering peel strength between the base fabric and the microporous layer. To prevent precipitation of polyurethane resin during the preparation for coating solution, for example, water should be mixed with DMF before being mixed with the coating solution.

SANAM Corporation SANPRENE LQ-258 Application Methods - 1

                   Figure 1. Relationship Between Evaporated Residue and Viscosity of Polyurethane Solution

 

3. Wet Process
The wet process includes the impregnation method that impregnates the base fabric with coating solution and then causes wet coagulation; and the coating method that coats the base fabric with coating solution and then causes wet coagulation. These methods are outlined below.
A. Impregnation Method
This method impregnates base fabrics including nonwoven fabric with coating solution, and then causes wet coagulation. This is a common method of producing suede-like poromeric and smooth poromeric leather. The merit of this method is the ability to produce leather that feels wellbonded with the base fabric.

SANAM Corporation SANPRENE LQ-258 Application Methods - 2

                               Figure 2. Schematic View of Impregnation Method

B. Coating Method
This method coats base fabric including woven fabric, knitted fabric or impregnated fabric with wet-process coating solution, and then causes wet coagulation. This is a common method of producing wet-process synthetic leather and smooth poromeric leather. The merit of this method the ability to produce leather of superior surface flatness.

SANAM Corporation SANPRENE LQ-258 Application Methods - 3

                            Figure 3. Schematic View of Coating Method

4. Examples of Coating Solution and Wet Process
Examples of coating solution formulas and the wet process for synthetic leather and promeric leather are shown below as applications of SANPRENE products (polyurethane resin solutions).
A. Microporous Layer of Smooth Synthetic Leather and Smooth Poromeric Leather
<Example Formulas of Coating Solution>
The numbers in the tables describe the weight ratio of the formula.

Soft Leather
General-Purpose Type
SANPRENE LQ-X5 100
DMF 100
IONET S-80 2
NEWPOL LB-1800X 2
Toner Proper Quantity

 

 Standard Leather
General-Purpose Type
SANPRENE LQ-336N: 100
DMF 100
IONET S-80 2
NEWPOL LB-1800X 2
Cellulose Powder 5
Toner Proper Quantity

 

 Hard Leather
General-Purpose Type
SANPRENE LQ-336N 50
SANPRENE LQ-660 50
DMF 100
SANMORIN OT-70 2
IONET S-80 2
Cellulose Powder 5
Toner Proper Quantity

 <Example of Wet Process>              Refer to Figure 3.
Pretreatment:
Performed through immersing the base fabric in water or aqueous solution of DMF, and
squeezing (70 - 90% pick up).
Coating:
Performed using a doctor blade. The amount of coating solution coated: 600 - 1200 g/m2
Coagulation: Performed in a coagulation bath containing 5 - 20 wt % aqueous solution of DMF at approx. 20°C for 5 - 10 min.
Rinsing: Performed in water at 40°C - 60°C for 10 - 30 min. During the rinsing process the cloth is squeezed several times using a mangle to remove residual DMF.
Drying: Performed at 120°C

B. Impregnated Layer of Poromeric Leather
<Example Formulas of Coating Solution>
The numbers in the table describe the weight ratio of the formula.

SANPRENE LQ-258:    100
DMF:                             150
Toner:           proper quantity

<Example of Wet Process> Refer to Figure 2.
Coating: Performed through immersing the base fabric (nonwoven fabric) in the coating solution and squeezing using a mangle. The amount of coating solution coated: 600 - 1200 g/m2
Coagulation: Performed in a coagulation bath containing 5 - 20 wt % aqueous solution of DMF at approx. 20°C for 5 - 10 min.
Rinsing: Performed in water at 40°C - 60°C for 10 - 30 min. During the rinsing process the cloth was squeezed several times using a mangle to remove residual DMF.
Drying: Performed at 120°C

Precautions Against Mishandling

  • When other resins are used together with these products listed in this brochure, test their compatibility beforehand to ensure that there are no problems.
  • Before use, completely dry the coating solution preparation bath, the coating machine, and other plant units. If moisture remains, part of the polyurethane resin solution in the coating solution coagulates and precipitates, resulting in formation of a microporous layer with inferior surface lubricity and tactile property.

Properties

Color
Physical Form
Appearance
Pale yellow to yellow liquid
Physical Properties of Dry Films
ValueUnitsTest Method / Conditions
100% Modulus11.3MPaISO 37-2011
Elongation at Break500ISO 37-2011
Evaporated Residue35wt %
Softening Point205°C
SolventDimethylformamide
Tensile Strength at Break61MPaISO 37-2011
Viscosity (20°C)105000mPaꞏs