ThreeBond Technical News
Issued January 1, 201585

Developing the Oily Surface andMagnesium Alloy Adhering FIPG
Introduction
Thanks to their flexibility when cured and excellent heat and chemical resistance, Silicone FIPG
(Formed In Place Gasket) s are used for a variety of sealing and adhesion applications such as inautomotive engine Areas. ThreeBond has developed products that have been specifically tailored
to meet our customers high requirements.
Recent years have seen manufacturers overhauling the manufacturing process, replacing iron,aluminum, etc., with lighter materials in order to reduce labor production costs and organic solvent
use while reducing vehicle fuel consumption. While investigations into reduction of degreasing
processes for cases and oil pans are a part of this overhaul, oil inevitably sticks to adherends forthese parts, necessitating FIPG that bonds with oily surfaces. Additionally, the magnesium alloys
and engineered plastics being considered for weight reduction are difficult to bond to, so increasing
the adhesive strength of FIPG is a major concern.
Here, we will introduce two of the latest in FIPG technology, our oily surface and lightweightmaterials (magnesium alloy) adhering FIPG.

Table of Contents
Introduction.................................................1
1. Background.............................................2
2. FIPG........................................................3
3. Required Characteristics........................4

4. Product Lineup........................................5
5. ThreeBond 1217M Evaluations...............6
6. ThreeBond 1217N Evaluations................7
Closing........................................................81

1.

Background

1-1 Automotive Industry Efforts
Recent years have seen the automotive industry and others
progress towards environmentally conscious manufacturing
through reductions in CO2 emissions, pollutants and vehicle
fuel consumption.
In order to both reduce emissions and use renewable
petroleum substitutes, hybrid (HV/PHV), clean diesel,
electric (EV), fuel cell (FCV) and other eco-friendly vehicles
have been released one after another, and their market sharecontinues to grow. Particularly for increased fuel-efficiency,
competition among manufacturers continues to steepen,with continued improvements from a variety of angles,
such as increasing motor/battery performance, optimizing
transmission and control systems and introducing highmileage oil and low resistance tires.

1-2 Developing Lightweight Materials
Weight reductions directly linked to fuel economy havealso continued, with parts being reduced both in size andcomplexity as the weight of the materials used to make themis reduced. Currently, aluminum (aluminum die casting)and iron (cation electrodeposition coated plate) are the twomaterials most widely used in areas such as automobile
engine blocks, cases and oil pans (Fig. 1). As an alternative
lightweight material, magnesium (Mg) alloy and nylonbased engineered plastics have gained traction, with various
tests underway geared towards their practical use.

1-3 Manufacturing Plant Efforts
Environmental efforts pursued in completed vehicles(products) have also taken hold in manufacturer productionlines, with a growing focus on improved productivity
coupled with reductions in CO2 emissions, organic
solvents and other pollutants leading to an overhaul ofmanufacturing processes (labor production cost reduction
and simplification). Degreasing processes used for theengine cases and oil pans are one target of these efforts, asorganic solvents are used.
1-4 Oil and Dirt on Adherends
Engine blocks and similar parts are usually produced bymolding and cutting iron or aluminum die cast. In thesecases, cutting oil is used as a process coolant, where acertain, a certain amount of which remains on the flangeeven after cleaning.
Additionally, various industrial equipment in operation
within an engine manufacturing plant scatter lubricant oil,creating a mist (small particles of oil in the air) that attaches
to adherends to cause oil leaks or deterioration to adhesivestrength and movement followability.

Applications: Adhesive sealant for oil pans, chain cases, etc.

Fig. 1 Parts Where FIPG are Used

2

2.

FIPG

2-1 What are FIPG?
Liquid gaskets (FIPG: Formed-in-Place Gasket) are used in
the process Currently RTV silicone is the most widely usedmaterial for FIPG.
*RTV: Room Temperature Vulcanizing
2-2 FIPG Seal Theory
While solid gaskets maintain a seal through repulsive force,
FIPG seal oily mediums mainly through bonding, adhesion,
viscoelasticity and cohesive force. These characteristics
must be excellent in order to seal sufficiently. fully seal (Fig.
2-1, 2-2).

2-3 Types of Leaks
The three main types of leaks are permeation (inner layer)leakage, where the inside of the gasket is penetrated by themedium, burst leakage, where the gasket itself breaks, andjunction leakage, where leakage occurs at the interface ofthe gasket and the flange (Fig. 3).

Permeation (inner surface) Leakage
Leakage where the interior of the gasket is penetrated
Mainly due to the gasket having insufficientchemical resistance

FlangeSolid Gaskets
GasketBurst Leakage

Seal Medium Pressure

Repulsive Force

Leakage from the broken surface of the gasket
Mainly due to gasket deformation, flange vibration

FlangeFig. 2-1 Solid Gasket Seal Theory

GasketLiquid Gaskets
Junction Leakage

Seal Medium Pressure

Bonding/Adhesion
Viscoelasticity/Cohesive Force

Leakage from the interface of the gasket and the flange
Mainly due to insufficient bonding/adhesion*Adhesion for each flange is vital

FlangeBonding/Adhesion

GasketFig. 3 Types of Leaks
Fig. 2-2 Liquid Gasket Seal Theory

There are various causes of leakage, FIPG are importantbecause of their durability for the sealed medium, ability tofollow flange vibrations and opening displacement and theirability to adhere to the flange.

33.

Required Characteristics

3-3 Durability versus Oil
Silicone FIPGs are used to seal engine and transmission
oils, so it is important that strength and elasticity do not
suffer in high temperatures (120°C or more), while also
ensuring effective adhesion (bonding) to the parts so they
can be properly used as a sealant.

3-1 Adhesion to Oily or Dirty Parts
Currently, degreasing processes are used to remove oil
attached to adherends, but as these processes are reduced
due to environmental concerns, this oil and dirt remains on
those surfaces.
Oil or dirt on an adherend greatly reduces adhesivestrength, which may then lead to market defects, and it is
the improvement of adhesion in this kind of well-known
situation for which FIPG are most needed.

3-4 High Elongation
FIPGs are mainly used in vehicle parts (such as engines ortransmissions) that vibrate or are subjected to impact, so theability to follow vibrations and displacement in openings
in those parts is required in addition to good adhesion.
Oil leaks occur due to FIPG fractures when displacement
followability is insufficient even if adhesion is sufficient.

3-2 Adhesion to Various Parts
While magnesium alloy, nylon and similar light-weightmaterials contribute to vehicle weight reduction, they arealso more difficult to bond to than aluminum, iron, etc.
This is why conventional FIPG, which do not bond well,must be improved and modified for use with these lightweight materials (see Fig. 4 for criteria used to determine
adhesiveness).

Cohesive Fracture (CF)* Cohesive fracture indicates thatadhesion is maintained in terms of thepart, which is desirable for the sealant

SideFront

Resin adheres
to both sides

Application
Test

Optimum bonding
Adhesive Fracture (AF)Side

Shear Test Piece
Side View

Resin on asingle sideFig. 4 Cohesive and Adhesive Fractures

4Front4.

Product Lineup

Here, we explore the features and properties of ThreeBond
1217M and ThreeBond 1217N (hereafter abbreviated toTB1217M and TB1217N, respectively), which overcome theissues presented above (Table 1, 2).

4-1 TB1217M: Oily Surface Adhesion and FIPG
Performance
TB1217M demonstrates excellent adhesion to oily surfaces.
Additionally, it boasts displacement followability, curability
and other characteristics such as chemical resistance equal tothat of conventional products. These traits make it excellent
for sealing and adhesion applications where conventional
FIPG products do not produce sufficient adhesion to oily anddirty surfaces which are the result in changes to degreasing
and cleaning processes.

4-2 TB1217N: Magnesium Alloy Adhesive FIPG
TB1217N demonstrates excellent adhesion to magnesium
alloys. Additionally, it boasts displacement followability,
curability and other characteristics such as chemical
resistance equal to that of conventional products. These traits
make it excellent for sealing and adhesion of lightweightmaterials (magnesium alloys) compared to conventional
FIPG.
* Adhesive performance varies depending on the type ofmagnesium alloy, so confirming with the material to be used isrequired.

* Effectiveness varies depending on oil type. Effectiveness forthe oil type, concentration and other factors must be checked
before use after degreasing.

Table 1 Properties
Conventional
ProductTB1217M

TB1217N

Testing Method

Curing Method

Oxime type

Oxime typeOxime type—Appearance

GrayBlackGray

3TS-2100-002

300

280

280

3TS-2F30-001

1.37

1.37

1.45

3TS-2500-002

Property

Viscosity

Unit

Pa·s

Specific gravity
Tack free time

min5763TS-3130-003

Thick film curingperformancemm/day

2.4

2.2

2.9

3TS-3160-005

Remarks

SOD* Test environment: 23°C, 50% RH

Table 2 Cured Material Characteristics
Cured Material
Characteristics

Unit

Conventional
Product

TB1217M

TB1217N

Testing Method

Hardness

—

A60

A45

A35

3TS-2B00-004

Elongation Rate%430

500

440

3TS-4190-005

Tensile StrengthMPa

2.6

2.5

3.13TS-4190-005

Shear Bond Strength

MPa

2.1

1.6

2.7

3TS-4100-023

Remarks

Al/Al* Curing conditions: 23°C, 50% RH×168h* Al: Aluminum55.

ThreeBond 1217M Evaluations

5-1 Oily Surface Adhesion
To check adhesion to oily or otherwise dirty parts, engine
oil was diluted to a specific concentration using a solvent,applied to an aluminum plate which was used as the test
piece, then the shear bond strength was checked (Fig. 5).
 Conventional FIPG
Shear bond strength, shear elongation (variation) and thecohesive fracture ratio all began to drop from an oily surface

concentration of around 1%, becoming almost entirely
adhesive fractures (AF) at around 5% (Fig. 6-1, 6-2).

 TB1217M
Adhesive performance was maintained, with no reduction
in shear bond strength, shear elongation or the cohesive
fracture ratio until reaching an oily surface concentration ofaround 7% (Fig. 7-1, 7-2).
The below study results indicate that TB1217M
demonstrates better adhesive performance on oily surfaces
than conventional FIPG products.

Test Piece Preparations
DippingDryingApplication

Assembling/Curing

Shear Bond Strength Testing

XSolution

Fig. 5 Test Piece Preparation
4.0

4.0

8.0

8.0

6.0

2.0

4.0

1.0

2.0

0.0

0.00%
Degreasing

1%3%

5%7%
Oily Surface
Concentration

10%15%

Fig. 6-1 Conventional FIPG Oily Surface Adhesion
Test Results
CF2.0

4.0

1.0

2.0

0.00%
Degreasing

0.0
1%

3%

5%

7%

3%

5%7%
Oily Surface
Concentration

10%

15%

Fig. 7-1 TB1217M Oily Surface Adhesion TestResults
CFAFOily Surface Concentration

10%Fig. 6-2 Fractured Conventional FIPG Test
Specimen Cross-Section66.0

AFOily Surface Concentration

1%

Shear Bond Strength
3.0

Shear Elongation (mm)Shear Bond Strength
3.0

Shear Bond Strength (MPa)Shear Elongation

Shear Elongation (mm)Shear Bond Strength (MPa)Shear Elongation

15%

1%

3%

5%

7%

10%15%

Fig. 7-2 Fractured TB1217M Test Specimen CrossSection

5-2 Long-Term Durability
The test specimen was cured at standard conditions (23°C,50% RH×168h), immersed in 150°C engine oil, then checked
for changes in physical properties.
TB1217M maintained more stable characteristics thanconventional FIPG after immersion in 150°C engine oil forup to 720 h (Fig. 8).

2.0

2.5

Conventional FIPG
Al/Al
Mg/Al

2.0

*Mg: Magnesium, Al: Aluminum

1.5

1.5

1.0

1.0

0.5

0.5

0.0

0.0
Conventional FIPG

TB1217M*Al: Aluminum

Fig. 8 TB1217M Long-Term Durability Oil Test
Results (Aluminum/Aluminum)

ThreeBond 1217N Evaluations

6-1 Magnesium Alloy Adhesion
The shear bond strength was checked using magnesium
alloy (AZ-91D) as the test specimen.
 Conventional FIPG
The poor adhesion to magnesium alloy indicates low shearbond strength, causing an adhesive failure (AF) on theadherend.
 TB1217N
Excellent shear bond strength to magnesium alloy that isequivalent to that to the aluminum (Table 3, Fig. 9).
Table 3 Magnesium Alloy Adhesion
Features

Al/Al

Shear Bond
Strength
Cohesive
Fracture Ratio
Shear Bond
Strength
Cohesive
Fracture Ratio

Unit

Conventional
TB1217N
FIPG

MPa

0.2

2.6%

0100

MPa

2.0

2.7%

100100

TB1217N
Al/Al
Mg/Al

Fig. 9 Shear Bond Strength Fracture

6-2 Long-Term Durability
TB1217N maintained better characteristics than conventional
FIPG in the same test conditions as in 5-2. Additionally,
TB1217N maintains excellent adhesion to magnesium alloy,
which is difficult to bond with (Fig. 10).
3.0

3.0
Mg Shear Bond Strength (MPa)Al Shear Bond Strength (MPa)

Initial
240h
480h
720h

2.5

Mg/Al

All fractures are
CF for TB1217N

3.0

3.0

6.

There is an AF on
the conventional
FIPG Mg

Initial
240h
480h
720h

2.5
2.0

2.5
2.0

1.5

1.5

1.0

1.0

0.5

0.5
0.0

0.0
Conventional FIPG

TB1217N*Mg: Magnesium

Fig. 10 TB1217N Long-Term Durability Oil Test
Results (Magnesium/Aluminum)

As described above, TB1217M and TB1217N demonstrateoily surface adhesion and adhesion to magnesium
alloy, respectively, while both have similar properties,characteristics and durability as conventional FIPG.

*Testing method: 3TS-4100-023*Mg: Magnesium, Al: Aluminum*Curing conditions: 23°C, 50% RH×168h7

Closing

The oily surface adhering TB1217M and magnesium adhering TB1217N FIPG introduced here are both products that aid inresource and environmental conservation while reducing processes required and helping to make vehicles lightweight. At
ThreeBond, we are constantly striving to further our technological development in order to create products that meet an everwidening range of customer needs.

ThreeBond Fine Chemical Co., Ltd. R&D Headquarters
Transport Development Division, Development Section
Masao Inoue
Yosuke Watanabe

ThreeBond Co., Ltd.
84-3-3 Minamiosawa, Hachioji,
Tokyo 192-0398
Tel: +81-42-670-5333