During polyurethane molding, we use a chemical additive called a release agent to prevent bonding. The mold release agent is very common in the production and processing of polyurethane, in the foaming process not only to prevent chemical reactions with polyurethane resin, and can effectively remove polyurethane products from the mold. But there are many people on the use of polyurethane release agents who have a variety of questions, as a professional release agent manufacturer, here we provide users with a detailed guide.
What are the sticky mold reasons in polyurethanes production and why should release agents be used?
Sticky Mold Reasons in Polyurethanes Production
👉Reason 1: The surface of the mold is usually covered by a thin or even single-molecule layer of film, which reacts with cyanate to produce strong adhesion.
👉Reason 2: Sticky matter is caused by the chemical bonds produced by the reaction of polar groups between the surface layer of the mold and polyurethane and polys veins.
The Principle of Using Release Agent
“The mold release agent mainly makes the mold surface form a dense smooth film, requires that the film does not react with polyurethane raw materials, the mold has a certain adhesion, at the same time to have a certain degree of flexibility. By spraying the effective release medium (usually an inert substance) evenly on the mold, a smooth film is formed after the medium has evaporated and dried, thus providing isolation and release effect.”
The Application Field and The Classification of Polyurethane Release Agent
Polyurethane foaming refers to a certain elasticity of a type of soft polyurethane foam, it is the largest use of polyurethane products. Products are mainly high rebound foam (HRF), block sponge, slow rebound foam, self-skin foam (ISF), imitation wood furniture, and semi-hard energy-absorbing foam.
Polyurethane soft bubbles have a pore structure that is mostly open. Usually has low density, breathability, sound absorption, insulation, good elasticity, and so on.
High rebound polyurethane foam is mainly used as furniture mats, vehicle seat cushions, a variety of soft cushion laminated composite materials. Industrial and civil also used soft foam as filtration materials, soundproofing materials, shock-proof materials, decorative materials, packaging materials, and insulation materials, soft polyurethane self-skin foam products are mainly used in the automotive steering wheel, headrests, handrails, motorcycle seats, bicycle seats, head rest, door handles, flow blockers and bumpers.
As a result, Sakurai release agents are divided into the following products for different applications of polyurethane products: PU Rigid foam release agent, PU Soft foam release agent, PU Integral skin release agent, PU Flexible foam release agent, PU slow rebound release agent, PU Shoe sole release agent, PU double density release agent, PU elastomer release agent, PU Headlining & Carpet foam release agent, PU sunroof edge release agent, PU filter foam release agent
The Effect of Release Agent on Polyurethane Foaming and Problem Solution
1. Problem: Product tearing, broken
🛠 Problem Description: Product release process due to the close combination of products and molds to remove the product when the product local tear.
👉 Possible Cause: The release agent spray is not in place, the release agent spray is too small.
⭐️ Solution: Uniform spraying of the entire mold, difficult release places to spray more release agents, recommended use of high-solid release agent products.
2. Problem: Product surface shrinks
🛠 Problem description: After the product has been released and pressed open, the surface still shrinks and bubbles.
👉 Possible cause: Too much mold release spray.
⭐️ Solution: Reduce the amount of release agent spray, excessive release agent is the use of mold temperature drop significantly, recommended to use high solid release agent products.
3. Problem: Large area of product surface problem
🛠 Problem description: A large area of thin film-like crust appears on the surface of the product, while a large area of holes appear under the crust.
👉 Possible cause: The raw material in the release agent reacts with the PU raw material.
⭐️ Solution: Replace the release agent and reduce the addition of silane components in the release agent.
4. Problem: Product local small area problem
🛠 Problem description: Product corner, the appearance of local bubble hole uneven, or local burning bubble, large empty bubble phenomenon.
👉 Possible cause: The release agent accumulates too much at the corner of the mold.
⭐️ Solution: Reduce the amount of local spray of release agent, use a spray gun with better atomization effect, local release agent too much use compressed air blow-off.
Technical challenges in the polyurethane industry occur from time to time, we as a professional manufacturer of release agents must keep pace with the times, equipped with the most comprehensive technical knowledge and practical ability to provide customers with suitable release agents, if necessary, we will go to the scene to assist and guide customers to use release agents.