LORD IMB TM 液体胶合质硅胶胶胶基础应用指南说明书

TM

®

LORD IMB Liquid Silicone Rubber Primers

Application Guide

LORD

®

In-Mold Bonding (IMB™) liquid silicone rubber (LSR)

primers are non-tacky polymer-based coatings that when

applied to a substrate provide a structural bond to a rigid

or elastomeric polymer, which is formed under heat and

pressure. LORD IMB 3000 series primers are designed

for bonding platinum-cured silicone rubber to a variety of

thermoplastic and metal substrates during the injection

molding process.

Although a premium primer is the basis of a quality bond,

it’s only the beginning; proper application is essential for

maximum results. Whether you’re dipping or spraying,

you’ll learn how to maximize efficiency and optimize results.

This guide also shows how to troubleshoot common

bond problems. We hope this resource will become an

indispensable part of your operation and a convenient,

one-source solution to many of your bonding questions.

character or quality of the treatment is affected by duration

of the blast; shape and size of the blasting media; particle

velocity; and the hardness, porosity and other substrate

properties.

Chemical processes, on the other hand, utilize organic and

inorganic chemicals to dissolve, suspend or eliminate soils

and surface contaminants. Preparation methods include:

• Alkaline cleaning

• Acid passivation

Selecting a Preparation Method:

To determine which preparation method best suits your

needs, consider:

• Economy – In large volumes, chemical treatments are

generally less expensive than mechanical methods.

• Versatility – Mechanical preparation methods may be

applicable to numerous metals, while chemical treatments

may be metal-specific.

• Adaptability to Existing Equipment – Existing facilities

may favor either mechanical or chemical processing.

• Adhesion Requirements – Adhesion requirements vary

from product to product, and bond quality is affected by

the particular application. Therefore, surface preparation

will vary accordingly.

• Environmental Resistance – Chemical conversion often

provides enhanced environmental resistance compared to

mechanical methods.

• Government Regulations – Waste disposal regulations

may prohibit the use of chemical treatments in certain

areas.

Substrate Surface Preparation:

One of the most important factors influencing adhesion

in the bonding process is surface preparation. To ensure

optimum bond performance and long-term environmental

resistance, substrates must be free of organic and inorganic

contaminants. Organic materials include grease, dirt and

oils which can be removed by solvent or alkaline cleaning.

Common inorganic contaminants are rust, scale and oxide

layers. These can be cleaned by either mechanical or

chemical processes, or a combination of both.

Types of Surface Preparation:

There are several ways to prepare substrates for primer

application; however, the methods can be broadly divided

into mechanical and chemical. Regardless of which method

you choose, the essentials of good surface preparations

include:

• Removal of all surface contaminants and decomposition

products.

• Prevention of recontamination.

• Careful handling through all processing steps.

Mechanical preparation involves physically removing surface

contamination and increasing surface area and substrate

profile. This method includes:

• Blasting – Abrasive particles (sand, grit or metal oxides) are

projected against the surface with a stream of air. Blasting

is especially effective for removing inorganic contamination

and other corrosion compounds found on metal. The

Maintaining Surface Conditions:

Maintaining optimum surface cleanliness is essential until

primer application is complete. To accomplish this:

• Apply the primer immediately after the surface is prepared.

• Avoid exposure to dust, moisture, chemical fumes, mold

release agents and other possible contaminants.

• Keep solvents and cleaning solutions free from

contamination, and replace when necessary.

• Ensure grits and abrasives remain clean and free of

contaminants.

• Check the purity of rinse water and “drying” air frequently,

ensuring minimal contamination.

LORD IMB LSR Primers — Application Guide

The water break test can be used to check for oil and

grease removal. If a surface can support an unbroken film

of deionized water for 60 seconds or more, it is considered

essentially free from grease or oil.

Applying the Primer:

LORD IMB primers may be applied by brush or spray

methods. General recommendation for dry film thickness is

2.0 to 5.0 micron (0.05 to 0.2 mil).

Hand Brushing – LORD IMB solvent-based primers are

suitable for hand brushing straight from the container. When

using this method, wear the proper personal protective

equipment, and work in a clean environment. Also make sure

there are no dirty or greasy objects within reach.

Spray Application – Spray application of primers is

particularly applicable when coating one side or certain

areas of a part. When spraying, however, it is important that

the primer reach the substrate wet. If drying occurs before

reaching the metal, adhesion will be poor.

Hand-held guns may be used for small runs, while

conveyorized or automated units are effective for large

production operations. And for small, intricate parts, an air

brush may be used. Regardless of size, properly adjusted

equipment ensures delivery of uniform films – without sags

and tears.

During hand-spray operations, parts are often assembled

on racks that incorporate masks wherever needed. If the

application requires overall coating, parts can be rotated in

front of the spray gun.

Precision Spray / Jetting – This technique follows the same

principles as typical spray techniques outlined above but

utilizes very precise application equipment to apply primer to

small areas with minimal overspray. LORD IMB primers are

compatible with this process.

Surface Preparation for Various

Substrates:

Although the general principles are the same for preparing all

substrates, some materials require special attention. Outlined

below are guidelines for surface preparation of specific

substrates.

Stainless Steel (Mechanical Preparation)

Preparing stainless steel with mechanical methods includes:

1. Blasting with sand or aluminum oxide. Steel grit should

not be used because it leaves ferrous deposits that can

cause galvanic corrosion.

2. One-hour layover maximum between blasting and

primer application.

Stainless Steel (Chemical Preparation)

Chemical treatment for the passivation of stainless steel

involves the following:

• Alkaline Wash

1. Hot water rinse (70°C)

2. Wash in sodium tripolyphosphate solution

3. Hot water rinse (70°C)

4. Hot air dry

• Acid Passivation

Washing step that uses mild acid solution such as citric or

oxalic acid

Immersion times, solution concentrations and operating

temperatures may be adjusted to suit conditions and alloys.

Plastics

LSR can be bonded to many rigid plastics. To prepare plastic

surfaces:

1. Solvent wipe. Hydrophobic solvents such as n-heptane

and Isopar

TM

can remove waxes and mold release.

Alcohol such as ethanol or isopropanol can remove

polar contaminants.

2. Surface oxidation by plasma, flame, or corona treatment.

Drying Processes:

All LORD IMB LSR primers can be dried at room temperature

(21°C/ 70°F) in 30 minutes or less. During the drying

process, no reaction is taking place – only solvent is

evaporating. Thus, methods to speed up solvent evaporation

are effective, such as increasing air flow or using hot air.

Heating to 65°C (149°F) in a convection oven for 5 minutes is

usually sufficient. Avoid drying temperatures of greater than

65°C (149°F). Avoid IR-based heating because this creates

a high level of heat directly at the primer surface, potentially

destroying the bonding ability.

Preparing the Primer:

Temperature – Temperature affects the viscosity of LORD

IMB primers. Recommended storage temperature is 21-

27°C (70-80°F) in original, unopened container. Cold storage

is not recommended.

Dilution – Regardless of dilution amounts, it is important in

all cases that the appropriate diluent be added to the primer

while stirring. Mixing guidelines are listed in the respective

technical data sheets for each LORD IMB product.

Handling Coated Parts:

Both clean and coated parts should be kept free of

contamination. Because fingerprints can adversely affect

adhesion, gloves are highly recommended. Thin, white,

cotton gloves are satisfactory, as they show soil easily, are

economical enough to be discarded when necessary, and

are thin and porous enough to be comfortable.

2

LORD IMB LSR Primers — Application Guide

Coated Parts Layover Stability:

Mold as soon as possible, but store all coated parts properly

to ensure maximum layover. Typically, this entails sealing

primer-treated substrates in a clean plastic container

and storing the package in a cardboard box. These

precautions ensure parts are protected from airborne

contaminates. Refer to the applicable technical data sheet

for recommended layover durations.

quick solutions. (In this document, the terms “elastomer” and

“primer” should be interpreted as “rubber” and “cement”,

respectively.)

Three basic ASTM designations are:

• RC – failure at the rubber-cement interface.

• CM – failure at the cover cement-metal interface; or at the

primer-metal interface.

• R – failure in the rubber.

Rubber-Cement (RC) Failures

Separation between rubber and cement is usually

characterized by a hard, glossy surface on the metal with

little or no visible rubber.

The following list includes common causes of RC failures, as

well as potential solutions:

• Substrate not hot enough upon LSR injection.

– Preheat the substrate inside of the mold by using an

injection delay or preheat the substrate in a batch oven to

minimize cycle time.

– Increase mold temperature.

• Silicone rubber contains low concentration of functional

groups.

– Increase amount of B component in two-part primers.

– If using single-component primer (LORD IMB 3050, for

example), mix with side B catalyst (LORD IMB 3040B, for

example). Details are provided in the respective technical

data sheets.

• Color concentrate contains incompatible components.

– Reduce or change color concentrate.

• Primer is sweeping, or being removed by flowing silicone.

– Reduce filling speed.

– Change gate location.

• Silicone is not compatible with primer.

– Change to a different grade of silicone.

Cement-Metal and Primer-Metal (CM) Failures

A clean separation between the primer and metal or other

substrate indicates that no adhesion has occurred.

The following list includes common causes of CM failure as

well as potential solutions:

• Substrate is not clean.

– Clean substrate; often, oil, dirt, dust or other

contaminants inhibit bonding.

• Primer is not sufficiently dried.

– Reduce dry film thickness (apply thinner).

– Increase drying time and/or temperature.

• Substrate is not compatible with primer.

– Mechanically roughen the substrate with abrasive.

– Chemically activate the substrate with plasma, flame, or

corona treatment.

– Change to a different substrate.

Molding Considerations:

One of the most important steps in the manufacturing

process is molding. During this phase, the primer-coated

substrate and elastomer are placed in the mold cavity, and

under proper conditions of time, temperature and pressure

the bonded assembly is formed.

Controlling each step in the molding process is critical to

bond success. Major variations in any step will cause bond

failures. Minor alterations, though not detrimental individually,

can collectively result in poor or marginal adhesion and

above-average scrap rates.

Considerations include:

• Primer Dry Film Thickness (DFT) – One of the most

important factors in environmental performance. Low and

high DFT films can result in poor performance. Refer to the

applicable technical data sheet for recommended DFT.

• Molding Pressure – Optimum adhesion requires

adequate pressure and intimate contact of elastomer and

primer during vulcanization and cure. Molds that are either

too tight or are too loose will hinder bond quality.

• Temperature – Dramatic temperature variations from

cavity to cavity may cause bond failure, lack of cure, or

overcure conditions. Mold temperature should be checked

periodically, particularly within the individual cavities.

Tempilsticks

®

, or selective melting-point wax pencils, are

excellent for spot-checking mold cavities. Thermocouples

can also be used, but they must be calibrated regularly.

• Mold Design – When designing the mold, provisions

should be made to facilitate substrate loading as well as

removal of the cured part.

Post Treatment:

Following part bonding, post-bake may be required to

achieve maximum bonding performance. A typical post-

bake condition for silicone parts is 150°C to 200°C (302°F to

392°F) for 2 to 4 hours.

Troubleshooting:

ASTM International provides a set of detailed symptom

descriptions for bond failures. These descriptions allow

complete and accurate problem assessment as well as

3

LORD IMB LSR Primers — Application Guide

Rubber (R) Failures

Rubber failures are separated into the following categories:

SR (Spotty Rubber) – Often caused by pre-bond surface

contaminants, this failure appears like splattered rubber on

the substrate surface.

TR (Thin Rubber) – Thin rubber failures are marked by even,

but very light rubber residue on the substrate surface. These

imperfections usually occur with butyl or rubber stocks

that are highly oil-extended. When oils migrate to the RC

interface, they create a bond layer that is part primer, part oil

and part rubber. This weak layer easily fails when the part is

stressed.

HR (Heavy Rubber) – A thick or heavy layer of rubber

remaining on the substrate surface indicates an excellent

bond. The stock fails because it is stressed beyond its

cohesive strength. This is the ideal failure mode.

SB (Stock Break) – With stock breaks, the elastomer appears

as if it was folded back on itself, then broken off. The break is

jagged and at a sharp angle to the substrate surface.

Although there are three primary bond failures, keep in mind

that rubber-cement, cement-metal/substrate and rubber

failures are often found in combination.

Safe Handling:

Proper handling of LORD IMB primers is essential for safe

and effective application. We recommend these procedures

be followed when using any LORD IMB LSR product:

• Read labels, SDS and technical data sheets before use.

• Ventilate application and storage areas.

• Wear proper personal protective equipment.

• Clean application and processing equipment regularly.

• Dispose of waste according to federal, state and local

regulations.

Parker LORD Applications

Laboratory:

As an extension of our product development efforts, Parker

LORD has injection molding machines in Erie, PA. By

simulating customers’ applications, we can provide detailed

technical support and more thoroughly evaluate optimum

application characteristics of new products.

Things to Avoid:

• Certain chemicals are incompatible with LORD IMB primers

and can cause failure. These include amines, sulfur, latex,

or chemical compounds containing nitrogen, phosphorous

or tin.

• Certain silicone components commonly used in other

primers. Make sure to avoid cross-contamination with

silane/silicone-based primers.

• Silicone-based mold release is not compatible with LORD

IMB primers. Use PTFE-based release agents, such as

McLube

TM

1711L.

Values stated in this document represent typical values as not all tests are run on each lot of material produced. For formalized product specifications for specific product end uses, contact the Customer Support Center.

Information provided herein is based upon tests believed to be reliable. In as much as Parker LORD has no control over the manner in which others may use this information, it does not guarantee the results to be obtained. In addition, Parker

LORD does not guarantee the performance of the product or the results obtained from the use of the product or this information where the product has been repackaged by any third party, including but not limited to any product end-user. Nor

does the company make any express or implied warranty of merchantability or fitness for a particular purpose concerning the effects or results of such use.

WARNING — USER RESPONSIBILITY. FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH, PERSONAL INJURY AND PROPERTY DAMAGE.

This document and other information from Parker-Hannifin Corporation, its subsidiaries and authorized distributors provide product or system options for further investigation by users having technical expertise.

The user, through its own analysis and testing, is solely responsible for making the final selection of the system and components and assuring that all performance, endurance, maintenance, safety and warning requirements of the application

are met. The user must analyze all aspects of the application, follow applicable industry standards, and follow the information concerning the product in the current product catalog and in any other materials provided from Parker or its

subsidiaries or authorized distributors.

To the extent that Parker or its subsidiaries or authorized distributors provide component or system options based upon data or specifications provided by the user, the user is responsible for determining that such data and specifications are

suitable and sufficient for all applications and reasonably foreseeable uses of the components or systems.

©2020 Parker Hannifin - All Rights ReservedInformation and specifications subject to change without notice

and without liability therefor. Trademarks used herein are the

property of their respective owners.

OD AG1024 06/20 Rev.1

Parker LORD

Engineered Materials Group

111 LORD Drive

Cary, NC 27511-7923

USA

phone +1 877 ASK LORD (275 5673)