UV Adhesive Defoaming Solution

One-stop solution for UV adhesive bubble issues from material characteristics to process parameters


UV Curable Adhesive is a functional adhesive material based on acrylate, epoxy acrylate, polyurethane acrylate and other matrices with added photoinitiators, which can achieve second-level curing under ultraviolet irradiation (365~405nm). Its core advantages include fast curing, no heating required and low VOC emissions. It is widely used in high-demanding industries such as optics, electronics, medical treatment and automotive. UV adhesives feature a wide viscosity range and prone photoinitiator sedimentation with special coating processes. Air bubbles are easily entrapped during production and application. Residual bubbles not only reduce optical transparency, but also lead to incomplete curing and bonding failure. SIENOX provides complete defoaming solutions from material selection to process for various UV adhesives via self-developed planetary mixing and defoaming technology.


◆ Material Characteristics

Common Matrix Types

Acrylate, Epoxy Acrylate, Polyurethane Acrylate

Photoinitiator System

TPO, 184, 651, 819, ITX, etc.

Curing Method

UV curing (365~405nm)

Common Viscosity Range

200~30,000 cps

Curing Speed

Several seconds to tens of seconds (depends on light intensity and coating thickness)

Typical Application Scenarios

Optical lenses, LCD panels, camera modules, wafer-level packaging


◆ Mature Application Fields

UV adhesives are widely adopted in high-demand industries including optics, electronics and medical devices. Main application fields and typical working conditions are listed below:


🔍 Optical Lens Bonding

Bonding of optical components for camera lenses and microscope objectives, requiring high light transmittance (≥95%), low yellowing and zero residual bubbles

📱 LCD/OLED Display Modules

OCA optical lamination between touch panel and display panel, requiring high transparency, bubble-free performance and resistance to humidity-heat aging

📷 Camera Module Packaging

Bonding and fixation of Lens and VCM motors for mobile/vehicle cameras, featuring low shrinkage, high-precision positioning and shadowless adhesive curing

💎 Wafer-Level Optical Packaging

Packaging and bonding for WLO wafer-level lenses and DOE diffractive optical elements, requiring nano-scale flatness and ultra-low bubble rate

🏥 Medical Device Assembly

Transparent component bonding for disposable medical consumables and in-vitro diagnostic equipment, requiring biocompatibility and bubble-free transparency

🔬 Optical Fiber Component Bonding

Alignment bonding of low-refractive-index UV adhesive for optical fiber couplers, optical waveguides and gratings, featuring low shrinkage and high positioning accuracy

🚗 Automotive Electronics Packaging

UV adhesive fixation for vehicle-mounted sensors, HUD head-up displays and lidar optical parts, requiring high temperature resistance and vibration resistance

🎧 Consumer Electronics Assembly

Fast bonding of optical and structural parts for TWS earbuds, smartwatches and AR/VR devices, requiring second-level positioning and flawless appearance

💡 Glass & Transparent Material Bonding

Transparent bonding for display cabinets, furniture, architectural glass and acrylic products, featuring high light transmittance, anti-yellowing and good weather resistance


◆ Core Problems Caused by Bubbles

🔍 Degraded Optical Performance

Bubbles form scattering points and abnormal refraction in the light path, reducing light transmittance and raising haze. Visible defects occur on optical lenses and display modules, directly downgrading product grade.

💔 Insufficient Bonding Strength

Bubbles occupy effective bonding area and create stress concentration points, lowering shear strength and peel strength. Debonding failure easily occurs under vibration and temperature cycling.

⚡ Incomplete Curing

Bubbles block UV light transmission. Photoinitiators in shaded areas cannot be fully excited, leading to incomplete curing and sticky surfaces in deep or thick coatings.

🎨 Appearance Defects

After curing, bubbles form visible white dots or pits inside transparent adhesive layers, severely damaging product appearance, which is unacceptable for consumer electronics and optical products.


◆ Recommended Process — Planetary Mixing & Defoaming

Planetary mixing and defoaming serves as the core process to eliminate bubbles in UV adhesives. Through planetary motion of rotation and revolution, efficient homogeneous mixing and defoaming are realized without impairing photoinitiator activity. UV adhesives are sensitive to ultraviolet light, so the whole process must be operated under yellow safety lights or light-shielded environments to prevent premature curing.


Step 1  Pre-mixing

Fully mix to redistribute photoinitiators and functional monomers evenly and avoid filler sedimentation or photoinitiator delamination caused by standing

Step 2  Container Loading & Parameter Setting

Select rotating speed according to viscosity (low viscosity:1000~1500rpm, medium viscosity:1500~2000rpm, high viscosity:2000~2500rpm)

Step 3  Mixing & Defoaming

Rotation and revolution run simultaneously. Vacuum assistance (-95KPa) can be added for medium and high viscosity materials to boost defoaming efficiency, with full light shielding during operation

Step 4  Discharging & Coating

Apply the adhesive immediately after defoaming. Operation under light-shielded environment is recommended. Control coating thickness to ensure sufficient UV penetration for full curing


◆ Recommended Equipment

  1. MIX60 — Suitable for low-viscosity UV adhesives (viscosity ≤3,000 cps). For laboratory / small-batch scenarios. Planetary motion with revolution and rotation, simple operation, quick cleaning, optional vacuum module.

  2. MIX90 — Suitable for medium-viscosity UV adhesives (3,000~10,000 cps). General-purpose model covering mainstream UV adhesives, balancing mixing and defoaming efficiency. Optional vacuum (-95KPa), ideal for small & medium batch production lines.

  3. MIX1000PLUS — For high viscosity and high capacity, viscosity 10,000~30,000 cps. Production-grade mixing defoamer with large processing volume and outstanding efficiency for continuous industrial operation, equipped with standard vacuum module.

  4. MIX2000 — For mass production and high-capacity requirements. Large-volume industrial defoamer with stable operation and simple maintenance, suitable for long continuous running, standard vacuum module.


◆ Test Cases

The following are field-tested defoaming cases of UV adhesives of different viscosity grades to verify the applicability of planetary mixing and defoaming process in various UV adhesive scenarios.


▶ Case 1: Low-viscosity Optical-Grade UV Adhesive

Item

Parameters

Test Material

One-component optical-grade UV adhesive (acrylate matrix, high light transmittance type)

Viscosity

Approx. 800 cps

Test Model

MIX60

Vacuum Degree

-95 KPa

Rotation Speed

1,500 rpm

Time

2 min

Temperature

Ambient Temperature (25℃)

✅ Defoaming Result: Bubbles are completely removed. The adhesive remains transparent and clear without impurities. No attenuation in light transmittance test, good optical uniformity after coating, meeting optical-grade requirements.


▶ Case 2: Medium-viscosity UV Adhesive for Electronic Assembly

Item

Parameters

Test Material

One-component UV adhesive for electronic assembly (epoxy acrylate matrix with a small amount of inorganic fillers)

Viscosity

Approx. 5,000 cps

Test Model

MIX90

Vacuum Degree

-95 KPa

Rotation Speed

2,000 rpm

Time

4 min

Temperature

Ambient Temperature (25℃)

✅ Defoaming Result: Bubbles are completely eliminated with uniformly dispersed fillers without agglomeration. The cured adhesive is dense and transparent, meeting bonding strength standards, suitable for precision bonding of camera modules and electronic components.


▶ Case 3: High-viscosity Thick-Coat UV Adhesive

Item

Parameters

Test Material

High-viscosity UV structural adhesive (polyurethane acrylate matrix filled with high-content inorganic fillers for thick-coat potting)

Viscosity

Approx. 18,000 cps

Test Model

MIX1000PLUS

Vacuum Degree

-95 KPa

Rotation Speed

2,000 rpm

Time

6 min

Temperature

Ambient Temperature (25℃)

✅ Defoaming Result: Bubble removal rate＞98% for high-viscosity paste. The adhesive returns to dense and uniform state. Fillers are evenly distributed without agglomeration or delamination. No residual bubbles inside after thick coating curing with full curing, and bonding strength meets structural component requirements.


◆ Comparison Before & After Improvement

Comparison Item

Before Defoaming

After Defoaming

Optical Transparency

Bubbles cause light scattering, lower transmittance and higher haze

Transmittance restored with good optical uniformity

Bonding Reliability

Bubbles reduce effective bonding area and easily lead to debonding failure

Dense adhesive with significantly improved bonding strength

Curing Completeness

Bubbles block UV light and result in incomplete deep curing

Uniform UV penetration for thorough curing without blind spots

Appearance Quality

Surface bubble traces and pits damage product appearance

Smooth flat surface with qualified appearance

Batch Consistency

Large fluctuation in bubble rate and unstable quality

Reproducible parameters and good batch consistency

Production Efficiency

High rework rate and reduced yield caused by bubbles

Improved first-pass yield and greatly reduced rework rate


🎯 Free Sample Testing
   Send us your UV adhesive samples. We will test defoaming parameters and issue test reports for you