Lösungsmittelkleben

Solvent bonding: Strong bonding of thermoplastics

Solvent bonding allows thermoplastics to be bonded permanently without any heat source and without any adhesive remaining. In this short and more technical article, we look at how it works, suitable solvents and the advantages of this technique.

The basics: bonding without heat or adhesive

The method of Solvent bonding, also known as cold welding or swelling welding, is a proven technique for joining thermoplastics.

Unlike thermal welding processes, solvent bonding does not require an additional heat source, but uses solvents to cross-link the polymer chains of the plastics to be bonded. This solvent evaporates in the process and, unlike conventional bonding processes, no adhesive layer remains.

This method is widely used in medical technology, the packaging industry and the production of technical parts.

DeepDive: Functioning of solvent bonding

How solvent bonding works:

Solvent bonding involves wetting the surface of the thermoplastics with a solvent. This solvent separates the polymer chains from each other, forming a plastic intermediate layer. Subsequently, the surfaces are combined under pressure to entangle the dissolved polymer chains. After evaporation of the solvent, a solid, homogeneous bond remains. This process enables a strong, durable bond that can withstand high mechanical stresses.

From our point of view, the advantages of this method are as follows: On the one hand, no adhesive layer remains between the plastics to be joined.

Infografik Lösungsmittelkleben — 1. Solvent is applied

3. Polymerketten werden gelöst — 3. Polymer chains are loosened

Commonly used solvent:

Dichloromethane (methylen chloride)
Acetone
Tetrahydrofuran (THF)
Methyl-ethyl-ketone (MEK)
Cyclohexanone
Ethylacetate
Toluol
Chloroform
Dichloroethane
Xylene

The solvent evaporates (almost) completely and, in contrast to an adhesive, is not part of the end product and therefore not part of the risk assessment. Compared to thermal processes, there is also the advantage that heat-sensitive parts are not exposed to heat during solvent bonding. However, whether solvent bonding is the best method depends on many parameters and especially on the respective application and should be considered individually.

Good to know: Bioplastics, such as PLA, can also be bonded by solvent bonding. Do you want to realize an application in this area made of bioplastics? Please do not hesitate to contact us!

In the following three tables we have compiled for you which solvents are suitable for which plastic classes (thermoplastics).

Which solvents are suitable for which thermoplastics?

Thermoplastic	Solvent
Polystyrene (PS)	Dichloromethane (methylen chloride) Toluol Acetone Ethylacetate Xylene Dichloroethane
Polyvinyl chloride (PVC)	Tetrahydrofuran (THF) Cyclohexanone Dichloromethane (methylen chloride)
Acrylonitrile butadiene styrene (ABS)	Acetone Methyl-ethyl-ketone (MEK) Dichloromethane (methylen chloride)
Polymethyl methacrylate (PMMA)	Dichloromethane (methylen chloride) Acetone Chloroform
Polycarbonate (PC)	Dichloromethane (methylen chloride) Chloroform
Polyethylene terephthalate glycol (PET-G)	Dichloromethane (methylen chloride) Methyl-ethyl-ketone (MEK)
Polysulphone (PSU)	Dichloromethane (methylen chloride)
Polylactid (PLA)	Chloroform Dichloromethane (methylen chloride) Methyl-ethyl-ketone (MEK) Tetrahydrofuran (THF)

Bonding different thermoplastics:

It is also possible to glue different thermoplastics together. However, this depends very much on the specific thermoplastics and the solvents used. For this purpose, it should be possible to “dissolve” both thermoplastics with a common solvent. Here are a few examples:

Thermoplastic	Solvent
ABS and PMMA	Acetone Dichloromethane (methylen chloride)
PS and ABS	Dichloromethane (methylen chloride)
PVC and ABS	Methyl-ethyl-ketone (MEK) Tetrahydrofuran (THF)

Solvent bonding with BIOVOX MedEco bioplastics

Our BIOVOX MedEco bioplastics ICB, ICB C1, IGH, XCB and XGB can also be bonded with solvents themselves and other thermoplastics. In the following overview we show which solvents and which solvents are suitable for this purpose:

A detailed overview with our materials can be found here

BIOVOX MedEco	Solvent
… and PVC	Dichloromethane (methylen chloride) Tetrahydrofuran (THF)
… and ABS	Dichloromethane (methylen chloride) Methyl-ethyl-ketone (MEK)
… and PMMA	Dichloromethane (methylen chloride) Chloroform
… and PC	Dichloromethane (methylen chloride) Chloroform
… and PET-G	Dichloromethane (methylen chloride) Methyl-ethyl-ketone (MEK)
… and PSU	Dichloromethane (methylen chloride)

Disclaimer: The information given here regarding the thermopaste and its solvent bonding properties is based on information from literature and other public sources. This information is intended for general guidance only. BIOVOX GmbH does not guarantee the accuracy of the data and does not assume any responsibility for its correct use. Therefore BIOVOX GmbH insists that all users test and verify the suitability under their individual conditions of use.

In a Nutshell: Solvent Bonding

The method of Solvent bonding is a method of bonding thermoplastics. A solvent dissolves the polymer chains of the plastics to be bonded, allowing them to interlace under pressure to form a permanent bond. This method does not require an additional heat source and does not leave an adhesive in the final product. Different solvents can be used for different classes of plastics.

Auch Bioplastics are also suitable for solvent bonding. Do you want to realize an application in this area made of bioplastics? Please do not hesitate to contact us!

More BIOVOX knowledge