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In dispensing, coating, screen printing, electronic assembly, packaging, and industrial bonding processes, adhesive materials may remain on dispensing valves, dispensing needles, valve bodies, pipelines, screens, and squeegee tools.
As production continues, adhesive residues may cause several problems:
Adhesive accumulation around valve outlets or dispensing needles may affect dispensing volume and accuracy.
Adhesive residues in screen mesh openings may cause blockage and uneven printing.
Adhesives may gradually cure, making equipment cleaning more difficult.
Residual adhesive may contaminate subsequent batches or affect the quality of the next production run.
Incomplete cleaning may affect equipment stability and production efficiency.
During equipment maintenance, some manufacturers consider using silicone oil to clean adhesive residues from glue valves or screens. In particular, they may consider dimethyl silicone oil because of its lubricating properties and water-repellent characteristics, hoping to reduce adhesive buildup or improve cleaning performance.
However, an important distinction must be made:
Dimethyl silicone oil is not a universal adhesive cleaner. It generally cannot dissolve and remove all types of cured adhesives, nor can it replace specialized cleaning agents designed for specific adhesive systems.
Silicone-based products may be used as auxiliary anti-stick, lubricating, or surface-treatment materials in certain processes. Whether they are suitable depends on the adhesive type, curing condition, equipment materials, and subsequent production requirements.
Different adhesives have different chemical compositions and curing mechanisms. Therefore, their cleaning methods may also differ.
A cleaning agent should not be selected solely according to the appearance or viscosity of the adhesive.
Common adhesive types and their cleaning considerations are listed below:
| Adhesive Type | Common Characteristics | Key Cleaning Considerations |
|---|---|---|
| Water-based adhesive | Uses water as the main dispersion or carrier medium; some products form a film after drying | First confirm whether water or a specified cleaning agent can remove the adhesive before it dries |
| Solvent-based adhesive | Contains organic solvents; forms an adhesive layer after solvent evaporation | Select a cleaning solvent compatible with the resin system |
| Hot-melt adhesive | Melts when heated and solidifies upon cooling | Evaluate suitable heating or specialized cleaning methods, considering equipment temperature limits |
| Epoxy adhesive | Commonly uses a two-component reactive curing system | Cleaning methods differ significantly between uncured and cured adhesive |
| Polyurethane adhesive | May be moisture-curing or a two-component reactive system | Confirm the curing mechanism, solvent compatibility, and resistance of equipment sealing materials |
| UV-curable adhesive | Cures through ultraviolet exposure | Clean before curing whenever possible; cured residues may require specialized cleaning or mechanical removal |
| Instant adhesive (cyanoacrylate) | Cures rapidly and can form a hard adhesive layer | Select a specialized removal method according to the substrate and equipment requirements |
| Silicone adhesive | Cures through moisture or other reaction mechanisms | Distinguish between uncured and cured material and confirm suitable cleaning or mechanical removal methods |
The table provides general classifications. The appropriate cleaning agent for a specific product should be confirmed through the adhesive manufacturer's technical documentation and cleaning recommendations.
This is one of the most important considerations when cleaning glue valves and screens.
Uncured adhesives
If the adhesive is still liquid or has not fully cured, it is generally easier to remove using an appropriate cleaning agent, wiping, flushing, or an equipment cleaning procedure.
For example, Dymax maintenance guidance for dispensing systems handling light-curable materials recommends using isopropyl alcohol (IPA) to clean uncured material from valves and other adhesive-contact components. The compatibility of the cleaning agent with equipment materials must still be confirmed.
Cured adhesives
Once an adhesive has cured, it generally forms a polymer structure with a certain degree of mechanical strength. Adding more solvent or silicone oil does not necessarily dissolve it.
Depending on the adhesive system, removal may require specialized swelling agents, adhesive removers, heating, or mechanical cleaning. The appropriate method depends on the adhesive chemistry and equipment structure.
DELO also explains in its technical guidance that cured adhesives are generally difficult to remove by ordinary dissolution and may require mechanical cleaning or solvent-assisted softening.
Therefore, before selecting silicone oil or a cleaning agent, it is essential to determine whether the adhesive has cured.
Dimethyl silicone oil, generally based on polydimethylsiloxane (PDMS), is a widely used organosilicone product.
Its typical properties include:
Good lubricating properties;
Good spreading characteristics;
Good thermal stability, depending on product grade and application conditions;
Hydrophobicity;
Good chemical stability;
Insolubility in water.
Due to these characteristics, dimethyl silicone oil is used in certain lubrication, anti-stick, surface-treatment, and industrial auxiliary formulations.
However, these properties do not mean that it can dissolve all types of adhesives.
Adhesives generally contain resins, polymers, solvents, fillers, and other additives. Different adhesive systems have different molecular structures and curing mechanisms, so they require corresponding solvents or cleaning systems for effective removal.
There is no universal dissolution relationship between dimethyl silicone oil and common adhesives.
For example:
For cured epoxy adhesives, ordinary dimethyl silicone oil cannot directly dissolve the cured material.
For cured polyurethane adhesives, ordinary dimethyl silicone oil cannot be relied upon for effective removal.
For UV-cured adhesives, dimethyl silicone oil cannot replace specialized cleaning agents.
For water-based adhesives, dimethyl silicone oil is insoluble in water and is not a general-purpose cleaning medium.
Therefore, if the objective is to completely remove adhesive residues that have accumulated on glue valves or screens, a specialized cleaning agent compatible with the specific adhesive system should generally be considered first.
Although dimethyl silicone oil is not a universal adhesive cleaner, it may be evaluated as an auxiliary material in certain specific applications.
(1) As an Auxiliary Anti-Stick Material
For certain external equipment surfaces where subsequent bonding, printing, or coating is not required, dimethyl silicone oil may be evaluated to determine whether it can reduce adhesive attachment or improve surface maintenance.
However, its anti-stick performance depends on the adhesive type, application method, surface condition, and actual contact conditions.
(2) As a Lubricating or Barrier Material
For certain moving equipment components or areas that do not come into direct contact with adhesive, silicone oil may be evaluated for lubrication or barrier applications, subject to equipment manufacturer recommendations.
However, dimethyl silicone oil should not be added directly to adhesive delivery pipelines or applied inside dispensing valves without prior compatibility testing.
(3) As an Auxiliary Material for Specific Dispensing Equipment Maintenance
Certain equipment maintenance procedures use oil-based materials with specific adhesives to prevent premature curing around nozzles or valve outlets.
For example, a Henkel operation manual for a specific high-pressure dispensing system mentions the use of paraffin oil to isolate moisture and prevent certain moisture-curing adhesives from curing prematurely at the nozzle. It also describes paraffin oil use in a specific silicone adhesive dispensing system.
However, this is a maintenance method designed for particular adhesive and equipment systems. It does not establish that ordinary dimethyl silicone oil will provide the same effect.
If dimethyl silicone oil is being considered for a similar purpose, the adhesive system, sealing materials, and equipment manufacturer's maintenance requirements must first be checked.
Before recommending a product, it is important to clarify whether the actual requirement is adhesive removal, anti-stick protection, or equipment lubrication.
These three requirements generally involve different product categories.
If the adhesive has not cured, a suitable cleaning agent should be selected according to the adhesive type.
For example:
| Adhesive Type | Cleaning Direction to Evaluate | Important Considerations |
|---|---|---|
| Certain water-based adhesives | Water or a cleaning agent recommended by the adhesive manufacturer | Confirm whether dried adhesive films can still be removed with water |
| Certain solvent-based adhesives | Organic solvents compatible with the resin system | Confirm equipment material compatibility and safety requirements |
| Certain UV-curable adhesives | Cleaning agents recommended by the adhesive manufacturer, such as suitable IPA-based systems | Distinguish between uncured and cured materials |
| Certain epoxy adhesives | Specialized cleaning agents or compatible cleaning products | Confirm the two-component system and curing condition |
| Certain polyurethane adhesives | Cleaning agents designed for the specific polyurethane adhesive system | Consider moisture curing, two-component curing, and material compatibility |
Note: These are general selection directions, not universal recommendations. A particular solvent may not be suitable for every adhesive within the same category. The specific choice should follow the adhesive manufacturer's cleaning instructions.
If the adhesive has already cured, ordinary silicone oil or general-purpose solvents may not effectively remove it.
Depending on the equipment material and adhesive type, the following methods may be evaluated:
Specialized adhesive removers;
Specialized swelling agents;
Mechanical scraping or disassembly and cleaning;
Heating or ultrasonic-assisted cleaning methods approved by the equipment manufacturer.
For example, 3M's screen-printing guidance for a specific epoxy adhesive recommends removing as much adhesive as possible by scraping first, followed by solvent treatment according to the adhesive curing condition. It also emphasizes following the solvent product label and Safety Data Sheet (SDS).
This illustrates why screen cleaning must be matched to the specific adhesive system. An ordinary oil-based product cannot simply replace every cleaning procedure.
If the objective is to reduce adhesive attachment to equipment surfaces rather than remove an existing adhesive layer, silicone-based anti-stick materials or specialized release agents may be considered.
Potential product categories include:
Dimethyl silicone oil;
Silicone oil emulsions;
Specialized silicone-based release agents;
Formulated anti-stick agents designed for specific adhesives and equipment conditions.
Dimethyl silicone oil may be considered as a candidate base material, but its compatibility with subsequent processes must be confirmed.
For example, if the screen will be used for further printing, or the valve surface must remain clean to ensure proper adhesive bonding, silicone oil residue may cause problems.
Therefore, anti-stick product selection should not focus only on whether the adhesive can be released easily. It must also consider whether the treatment creates new surface contamination.
Dimethyl silicone oil has good spreading properties and hydrophobic characteristics. Even a small amount of residue may change the surface wetting behavior.
If the glue valve, screen, or workpiece will subsequently undergo bonding, coating, or printing, silicone oil residue may cause:
Uneven adhesive wetting;
Localized bonding failure;
Reduced coating adhesion;
Surface defects such as craters or fisheyes;
Uneven surface contamination.
Therefore, if subsequent processes require a high level of surface cleanliness, silicone oil should not be sprayed or wiped onto the equipment without prior validation.
The internal structure of a dispensing valve may include sealing rings, valve needles, diaphragms, hoses, and other precision components.
Different equipment systems may use different types of rubber, plastics, and metals.
Even if a silicone oil has good chemical stability, this does not guarantee compatibility with every sealing material, adhesive, or equipment component.
The following points should be confirmed:
Sealing material type;
Pipeline material;
Internal valve structure;
Potential interactions between the adhesive and silicone oil;
Whether the equipment manufacturer permits the use of the selected oil.
Unless the formulation has been properly evaluated, dimethyl silicone oil should not be added directly to adhesives.
Silicone oil may change the adhesive's surface wetting, rheological behavior, and interfacial properties. It may also affect bonding performance, curing behavior, or the appearance of the final product.
For applications requiring high bonding strength, precision coating, or subsequent printing, cross-contamination by silicone-based materials should be strictly controlled.
Organic solvents and specialized adhesive removers may be volatile, flammable, or irritating.
During cleaning operations:
Read the cleaning agent's SDS;
Wear appropriate protective gloves and safety goggles;
Ensure adequate ventilation;
Avoid contact with incompatible equipment materials;
Do not mix different cleaning agents without confirming compatibility;
Dispose of cleaning waste and adhesive residues according to local regulations.
If a customer wants to evaluate dimethyl silicone oil, its actual function should first be confirmed through small-scale testing. It is not recommended to apply it directly throughout the entire equipment system.
The following steps are recommended.
Confirm whether the adhesive is epoxy, UV-curable, polyurethane, silicone, instant adhesive, water-based, or hot-melt adhesive.
Also determine whether the adhesive has already cured.
Determine which problem the customer wants to solve:
Removing existing adhesive residues;
Preventing adhesive from sticking to the glue valve or screen;
Preventing premature curing around the valve outlet;
Improving lubrication of moving equipment components;
Reducing equipment maintenance caused by adhesive buildup.
Only after the objective has been clarified can the appropriate product category be identified: a cleaning agent, silicone oil, or a specialized anti-stick product.
Select a small area or a non-critical equipment component for preliminary testing. Observe:
Whether the adhesive softens or detaches;
Whether the silicone oil spreads evenly;
Whether an oil film remains on the equipment surface;
Whether sealing materials swell, soften, or show other abnormal changes;
Whether visible residues remain after cleaning.
If the objective is adhesive removal, the actual residue before and after cleaning should be compared. A surface that merely looks smoother does not necessarily indicate effective cleaning.
If the equipment will continue dispensing, printing, or bonding after cleaning, further evaluation is necessary.
Check:
Whether adhesive dispensing remains stable;
Whether the adhesive wets the substrate properly;
Whether bonding strength changes;
Whether screen printing develops craters or localized defects;
Whether oil contamination remains on the product surface.
The proposed method should only be introduced into actual production after cleaning performance, material compatibility, and subsequent product quality have all been verified.
Ordinary dimethyl silicone oil is not a universal adhesive cleaner.
It has lubricating, spreading, and hydrophobic properties, but it cannot dissolve or remove all types of adhesives. In particular, cured epoxy, polyurethane, and UV-curable adhesives generally require specialized cleaning agents or mechanical removal methods.
If the objective is to prevent certain adhesives from sticking to equipment surfaces, dimethyl silicone oil may be evaluated as an auxiliary material. However, it should not be treated as a cleaning agent.
In general, ordinary dimethyl silicone oil is not recommended as a screen adhesive cleaner.
Adhesive residues on screens may block mesh openings or adhere to the screen surface and squeegee tools. Cleaning must consider the screen material, photo-emulsion or screen coating, adhesive type, and curing condition.
A cleaning agent compatible with the specific adhesive and screen system should be selected first.
3M's cleaning guidance for a specific epoxy adhesive used in screen printing also recommends solvent-based cleaning methods designed for that adhesive rather than ordinary silicone oil.
Silicone-based materials may be evaluated as auxiliary anti-stick materials under certain conditions, but their performance is not the same for all adhesives.
The adhesive type, valve material, silicone oil viscosity, application method, and subsequent dispensing requirements must all be considered.
If silicone oil enters the adhesive flow path or contaminates the dispensing area, it may affect adhesive wetting and bonding performance. Therefore, the equipment manufacturer's approval should be obtained before use.
A specialized adhesive remover or a cleaning method recommended by the equipment manufacturer should generally be considered first.
Cured adhesives have formed polymer structures, and ordinary dimethyl silicone oil cannot universally dissolve these residues.
The appropriate cleaning method depends on the adhesive chemistry, degree of curing, equipment material, and cleaning requirements.
Neither should automatically be regarded as a universal adhesive cleaner.
Dimethyl silicone oil is an oil-based product and is insoluble in water. Silicone oil emulsions use an emulsification system to disperse silicone oil in water.
If the customer needs auxiliary lubrication or anti-stick performance, pure silicone oil or an emulsion may be evaluated according to the application method.
However, if the objective is to remove adhesive residues, a specialized cleaning agent should be considered first rather than simply comparing silicone oil with silicone oil emulsion.
Yes, it can.
Dimethyl silicone oil may leave hydrophobic residues on equipment or workpiece surfaces, changing how adhesives wet those surfaces and potentially affecting subsequent bonding or coating.
If the glue valve or screen will be used for further bonding, printing, or coating, the effect of silicone oil residue on product quality must be thoroughly evaluated.
Viscosity affects silicone oil flowability, spreading, and surface film retention.
Low-viscosity silicone oil generally has better flowability and may spread more easily. Higher-viscosity silicone oil has lower flowability and may exhibit different film-retention characteristics.
However, viscosity alone does not determine anti-stick performance. The actual result also depends on adhesive type, surface material, application amount, and contact conditions.
It is recommended to compare different viscosity grades under controlled conditions rather than assuming that higher viscosity always provides better anti-stick performance.
If the process has been confirmed to be compatible with silicone oil, the following parameters should be considered:
Kinematic viscosity and test temperature;
Product appearance and batch consistency;
Volatility and relevant specifications;
Product purity and impurity control;
Compatibility with adhesives and equipment materials;
Availability of a complete Technical Data Sheet (TDS) and Safety Data Sheet (SDS);
Availability of different viscosity grades for customer testing.
It is important to note that the standard technical specifications provided by a silicone oil supplier cannot replace actual adhesive cleaning or anti-stick performance tests. Final suitability must be determined under the customer's real operating conditions.
There is no single silicone oil that can solve every adhesive residue problem on glue valves, screens, and dispensing equipment.
If the objective is to remove uncured or cured adhesive, first identify the adhesive type and curing condition. Then select a cleaning agent or removal method compatible with the adhesive system and equipment materials.
If the objective is to reduce adhesive attachment, provide auxiliary lubrication, or improve anti-stick performance on specific equipment surfaces, dimethyl silicone oil, silicone oil emulsions, or specialized silicone-based anti-stick products may be evaluated.
Dimethyl silicone oil offers lubricating, spreading, and hydrophobic properties. However, it should not be promoted as a universal adhesive cleaner, nor should it be assumed suitable for every glue valve, screen, or adhesive system.
For industrial users, the recommended approach is to clarify the cleaning objective first, then conduct small-scale and production trials based on adhesive type, equipment structure, material compatibility, and downstream process requirements.
The correct selection principle is: choose a cleaning agent to remove adhesive, evaluate an anti-stick agent to reduce adhesion, and consider a lubricant to improve equipment friction.
