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IOTA LSR 3920 is a two-component liquid silicone rubber designed for high-strength silicone molding applications.
The product is described as a baby care-grade high-strength fumed liquid silicone rubber and provides high transparency together with a range of mechanical properties.
The 3920 series includes six hardness grades:
IOTA LSR 3920-20 — Shore A 20
IOTA LSR 3920-30 — Shore A 30
IOTA LSR 3920-40 — Shore A 40
IOTA LSR 3920-50 — Shore A 50
IOTA LSR 3920-60 — Shore A 60
IOTA LSR 3920-70 — Shore A 70
This hardness range allows manufacturers to select a formulation according to the flexibility, strength and finished-product requirements of the application.
The IOTA LSR 3920 series combines high transparency, high mechanical strength and six different hardness options.
| Property | 3920-20 | 3920-30 | 3920-40 | 3920-50 | 3920-60 | 3920-70 |
|---|---|---|---|---|---|---|
| Appearance | Transparent | Transparent | Transparent | Transparent | Transparent | Transparent |
| Viscosity | 2000 Pa·s | 2500 Pa·s | 3000 Pa·s | 3500 Pa·s | 4000 Pa·s | 4000 Pa·s |
| Hardness | Shore A 20 | Shore A 30 | Shore A 40 | Shore A 50 | Shore A 60 | Shore A 70 |
| Density | 1.10 g/cm³ | 1.10 g/cm³ | 1.11 g/cm³ | 1.12 g/cm³ | 1.12 g/cm³ | 1.14 g/cm³ |
| Tensile Strength | 6.5 MPa | 7.5 MPa | 9.0 MPa | 9.5 MPa | 9.5 MPa | 9.0 MPa |
| Elongation at Break | 850% | 780% | 650% | 500% | 400% | 300% |
| Tear Strength | 12 kN/m | 15 kN/m | 30 kN/m | 35 kN/m | 30 kN/m | 30 kN/m |
| Linear Shrinkage | 2.1% | 2.1% | 2.1% | 2.0% | 2.0% | 2.0% |
Values are based on the product technical data. Actual production performance may vary according to molding conditions, geometry, curing conditions and processing equipment.
The main advantage of the 3920 series is its six-grade hardness range from Shore A 20 to Shore A 70.
Hardness selection affects the flexibility, tactile feel, deformation resistance and mechanical behavior of the finished silicone product.
3920-20 is the softest grade in the series.
It provides:
Shore A 20 hardness
6.5 MPa tensile strength
850% elongation at break
12 kN/m tear strength
The 850% elongation makes this grade suitable for applications where high flexibility and elastic deformation are important.
3920-30 provides a balance between softness and mechanical strength.
Its listed properties include:
Shore A 30 hardness
7.5 MPa tensile strength
780% elongation
15 kN/m tear strength
It can be considered when the finished product requires both flexibility and higher mechanical strength than the Shore A 20 grade.
3920-40 provides:
Shore A 40 hardness
9.0 MPa tensile strength
650% elongation
30 kN/m tear strength
Its combination of tensile and tear strength makes it suitable for products requiring greater mechanical durability.
3920-50 provides the highest listed tear strength in the series:
Tear strength: 35 kN/m
It also provides:
Shore A 50 hardness
9.5 MPa tensile strength
500% elongation
This grade can be considered when mechanical strength and tear resistance are important.
3920-60 provides:
Shore A 60 hardness
9.5 MPa tensile strength
400% elongation
30 kN/m tear strength
It provides a harder silicone structure while retaining substantial elongation.
3920-70 is the hardest grade in the series.
Its listed properties include:
Shore A 70 hardness
9.0 MPa tensile strength
300% elongation
30 kN/m tear strength
It can be considered for products where higher hardness and shape retention are required.
Choose the hardness according to the finished product's required flexibility, mechanical strength and deformation resistance.
A simplified selection guide is:
| Application Requirement | Suggested Grade Range |
|---|---|
| Very soft and highly flexible silicone | 3920-20 |
| Soft and flexible silicone | 3920-30 |
| Balanced flexibility and strength | 3920-40 |
| Higher strength and tear resistance | 3920-50 |
| Harder silicone with high strength | 3920-60 |
| Highest hardness in the series | 3920-70 |
This table is a starting point rather than a substitute for application testing.
The appropriate grade should also be evaluated according to product geometry, mold design, required demolding behavior, compression requirements and end-use conditions.
IOTA LSR 3920 provides tensile strength up to 9.5 MPa.
The tensile strength varies according to hardness:
3920-20: 6.5 MPa
3920-30: 7.5 MPa
3920-40: 9.0 MPa
3920-50: 9.5 MPa
3920-60: 9.5 MPa
3920-70: 9.0 MPa
The highest listed tensile strength is 9.5 MPa, achieved by both 3920-50 and 3920-60.
This allows manufacturers to select a hardness grade without relying on a single formulation for all product designs.
The IOTA LSR 3920 series provides elongation at break from 300% to 850%.
The softest 3920-20 grade has the highest listed elongation at break of 850%.
The elongation values decrease as hardness increases:
Shore A 20: 850%
Shore A 30: 780%
Shore A 40: 650%
Shore A 50: 500%
Shore A 60: 400%
Shore A 70: 300%
This relationship provides a useful reference when selecting silicone hardness for flexible products.
IOTA LSR 3920 provides tear strength up to 35 kN/m.
The listed tear strength is:
3920-20: 12 kN/m
3920-30: 15 kN/m
3920-40: 30 kN/m
3920-50: 35 kN/m
3920-60: 30 kN/m
3920-70: 30 kN/m
3920-50 provides the highest listed tear strength at 35 kN/m.
For products with thin sections, edges or repeated deformation, tear strength should be considered together with hardness and elongation.
All six IOTA LSR 3920 grades are listed as transparent.
High transparency can be useful when the appearance of the finished silicone product is important.
The transparent material can also be considered when manufacturers want to maintain visual clarity or add transparent color effects to the final product.
However, final optical appearance depends on the mold, pigment, processing conditions, curing process and product thickness.
IOTA LSR 3920 uses a 1:1 mixing ratio for Part A and Part B.
The manufacturer recommends using metering and mixing equipment capable of conveying, metering and mixing the two components while minimizing air infiltration.
Step 1 — Metering
Measure Part A and Part B at a 1:1 ratio.
Step 2 — Mixing
Mix the two components thoroughly until the material is uniform.
Step 3 — Air Removal
The supplied components are filtered and deaerated.
If additional air bubbles are introduced during mixing, vacuum equipment should be used to remove the air before molding.
Step 4 — Molding
Transfer the mixed silicone into the mold using suitable molding equipment.
Step 5 — Vulcanization
The listed first curing condition is:
130°C for 5 minutes.
Actual curing time depends on product thickness, mold temperature and production conditions.
IOTA LSR 3920 cures rapidly at elevated temperature.
The manufacturer's listed initial curing condition is 130°C for 5 minutes.
Actual curing behavior depends on:
Silicone thickness
Mold temperature
Mold design
Production equipment
Material temperature
Curing conditions
Certain materials can inhibit the curing reaction.
The product page specifically identifies amines, sulfur and tin compounds as materials that can inhibit curing.
Therefore, processing equipment, additives, pigments, release agents and substrates should be checked for compatibility before mass production.
IOTA LSR 3920 is suitable for producing a range of silicone products.
The product page identifies applications including:
Baby care products
Kitchen products
Industrial seals
Washers
Other molded silicone products
The product is identified as baby care-grade and can be considered for silicone products where transparency, flexibility and mechanical strength are required.
For specific baby-contact applications, manufacturers should independently verify the applicable regulatory and food-contact requirements for the target market and finished product.
The material can be used for selected kitchen silicone products requiring flexible and transparent silicone rubber.
The appropriate hardness should be selected according to the required product structure and mechanical performance.
Different 3920 hardness grades allow manufacturers to select the material according to sealing geometry and required flexibility.
The series can also be considered for molded washer products where silicone flexibility, strength and temperature resistance are required.
Different silicone products require different combinations of flexibility, strength and hardness.
A soft baby-care product may require a very different material response from an industrial washer or seal.
The six-grade IOTA LSR 3920 series provides a hardness range of:
Shore A 20 → 30 → 40 → 50 → 60 → 70
This gives manufacturers multiple material options within one product series.
Instead of modifying the formulation for every application, manufacturers can first evaluate the six standard grades according to the finished product requirements.
IOTA LSR 3920 should be stored in the unopened original container at temperatures of 32°C or below.
The listed storage life is 9 months.
Material beyond the stated storage period may be used after passing appropriate re-inspection.
After Part A and Part B are mixed, the mixture is listed as usable for 48 hours at 25°C.
IOTA LSR 3920 is available in:
200 kg net weight — 55-gallon steel drum
20 kg net weight — 20 L straight plastic drum
Packaging can therefore support both smaller production requirements and larger-scale industrial manufacturing.
Need very soft transparent silicone?
Consider IOTA LSR 3920-20, Shore A 20 with up to 850% elongation.
Need a soft but stronger silicone?
Consider 3920-30, with Shore A 30 hardness and 7.5 MPa tensile strength.
Need balanced hardness and mechanical strength?
Consider 3920-40, with Shore A 40 hardness and 9.0 MPa tensile strength.
Need the highest listed tear strength?
Consider 3920-50, with tear strength of 35 kN/m.
Need harder silicone with high tensile strength?
Consider 3920-60, with Shore A 60 hardness and 9.5 MPa tensile strength.
Need the hardest grade in the series?
Consider 3920-70, with Shore A 70 hardness.
Need a 1:1 liquid silicone rubber system?
All IOTA LSR 3920 grades use a 1:1 Part A to Part B mixing ratio.
IOTA LSR 3920 is a baby care-grade, high-strength fumed liquid silicone rubber designed for transparent molded silicone products and other applications requiring different hardness and mechanical properties.
Yes. The six 3920 grades are listed as transparent.
The mixing ratio of Part A to Part B is 1:1.
The IOTA LSR 3920 series is available in Shore A 20, 30, 40, 50, 60 and 70.
3920-20 is the softest grade, with Shore A 20 hardness.
3920-20 has the highest listed elongation at break, at 850%.
3920-50 and 3920-60 both have a listed tensile strength of 9.5 MPa.
3920-50 has the highest listed tear strength at 35 kN/m.
The listed initial curing condition is 130°C vulcanization for 5 minutes. Actual curing time depends on material thickness and curing temperature.
The product information identifies amines, sulfur and tin compounds as materials that can inhibit curing.
Store the unopened original container at 32°C or below. The listed storage life is 9 months.
The product is listed for applications including baby care products, kitchen products, industrial seals, washers and other silicone products.
The mixed material is listed as usable for 48 hours at 25°C.
Product: IOTA LSR 3920 Baby Care-Grade High-Strength Fumed Liquid Silicone Rubber
Type: Two-component liquid silicone rubber
Mixing Ratio: 1:1
Appearance: Transparent
Hardness Range: Shore A 20–70
Maximum Tensile Strength: 9.5 MPa
Maximum Elongation: 850%
Maximum Tear Strength: 35 kN/m
Initial Curing Condition: 130°C × 5 minutes
Storage Temperature: ≤32°C
Storage Life: 9 months
Main Applications: Baby care products, kitchen products, industrial seals, washers and other molded silicone products
