Three Bond Technical News
Issued January 1, 2008

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Automobile Coating AgentIntroduction ________________________________________________
Over the years ThreeBond has developed and marketed chemical products for automobile maintenancetargeted to the automotive aftermarket. These products include brake cleaners for use in brake maintenance,chassis paints to serve as an anti-rust coating for automobile undercarriages, and anti-rust and lubricating agentsfor use in auto repair, inspection, and maintenance. Meanwhile, in recent years, the automobile industry has been
faced with growing concern over the issue of global environmental conservation; consumers are demanding carsoffering higher mileage, enhanced environmental friendliness, and increased safety. Furthermore, consumers are
increasingly insisting on longevity, a lasting appearance, and comfort in the cars they purchase. In order to keep
pace with such heightened environmental awareness and to respond to these changing consumer demands,
ThreeBond has applied its expertise in a variety of resin and coating technologies accumulated over the years
since its founding to develop a coating agent that will enhance both the interior and exterior of the automobile.
The present report will introduce a body/wheel coating agent which was placed on the market in 2005, awindshield water repellant, and a tire-coating agent, the latter two of which were introduced to the market thisyear, in addition to a discussion of the peripheral technologies associated with these products.

Contents
Introduction ....................................................... 1
1. Body/Wheel Antifouling Coating Agent......... 2
1-1. Polysilazane ......................................... 2
1-2. Low Water Repellencyof the Glass Coating ............................. 2
1-3. Anti-fouling Effect of TB6644................ 3
1-4. Weather-resistance of TB6644............. 3
1-5. Protection from Iron Powder
with TB6644G....................................... 3
2. Windshield Water Repellant ......................... 4
2-1. Water-repellence of Solid Surfaces ...... 4
2-2. Application to Water Repellantsfor Automobile Windshields .................. 4

2-3. TB6550E — High-durability Water
Repellant for Glass................................5
2-4. Ice Suppression Effect of TB6550E ......5
3. TB6641B Ultra Tire Coating Agent................5
3-1. Tire Weathering.....................................5
3-2. Anti-weathering Mechanismof TB6441B ...........................................6
3-3. Durability of the TB6441B Coating........6
3-3-1. Durability Test (Accelerated
Weathering Test)........................6
3-3-2. Durability Test (Flexural
Fatigue Test) ..............................6
3-4. Plans for Future Development ..............7
4. Conclusion ....................................................81

1.

Body/Wheel Antifouling Coating
Agent

Admixtures of wax and petroleum solvents weretraditionally marketed as polishing wax to add gloss
to the auto body. Then, with the appearance ofsilicone compounds and fluorine compounds on themarket, water repellency became recognized as animportant feature of a product, in addition to gloss.
However, as these products permeated the market,
their adverse effects have come to attention—inparticular, the presence of water spots, or marks
arising from contact with water, raindrops, or thelike.
Unlike conventional water-repellant coating
agents, the polysilazane-based ThreeBond 6644
Series (Ultra Glass Coating) coating agent for
automobiles actually prevents water spots and stains
through its low water repellency.
1-1. Polysilazane
Polysilazane is a high polymer compound madeof repeating units of silicon (Si) and nitrogen (N) ina molecular chain. The compound converts to silica(SiO2) through oxidation reaction—a useful,high-tech,material
property
suitableforapplications such as high-performance insulating
coatings for electronic devices1) and functionaltransmissive coatings2).
–(Si-–N)n– → – (Si–O)n–In the ThreeBond 6644 (“Threebond” ishereinafter abbreviated as “TB”) series,
polysilazane has been adopted as a base to produce
a new type of automobile coating agent that in fact
forms a glass (SiO2) coat on the auto body.
Figure 1 presents the infrared (IR) spectra
obtained by infrared spectroscopy, which shows
how the applied TB6644 auto-body coating agent
and TB6644B curing accelerator is converted into a
glass coating. As the figure shows, the intensity ofthe (Si–N) peak at 900-950 cm-1 decreases whilethat of the (Si–O) peak near 1,015 cm-1 increases
relative to the (Si–CH3) peaks near 1,265 cm-1 and780 cm-1, reflecting the conversion from Si–N to
Si–O.
1-2.

Low Water Repellency of the Glass
Coating
Mainstream
auto-bodycoating
agentstraditionally boasted high water repellency, withwater droplets beading and bouncing off the vehicle
body to which the agents were applied. However,recent years have witnessed a growing awareness ofthe problem of water-spot formation—e.g., marks
from raindrops or other water marks caused by thebeads of water remaining on the auto body. Sincesuch water droplets are likely to contain the2

Immediately after application

After curing
Figure 1. IR spectra of TB6644/6644B
coating
atmospheric pollutants nitrogen oxide (NOx) andsulfur oxide (SOx) that cause acid rain, the drying
of such water droplets on the auto body often results
in a residue of more strongly acidic droplets. Such
residues corrode the paint and may cause so muchdamage as to require complete re-painting of theautomobile.
These disadvantages of water-repellant agents
have been overcome with the TB6644 series
product, through the adoption of a strategy of low
water repellence. Although the definition ofhydrophilic characteristics and water repellency are
rather ambiguous, generally, a surface of a solid isconsidered to be water repellant when the angle ofcontact with water is over 90 degrees, and whenless than 30 degrees, is considered hydrophilic. The
angle of contact for the TB6644 series is 75–80
degrees, and this property is what provides a surface
that reduces residual water droplets compared toconventional water-repelling agents.

1-3. Anti-fouling Effect of TB6644
Photo 1 shows the results of a test performed to
study the product’s anti-fouling properties. An
artificial dirt solution was prepared by creating asuspension of industrial test powder (JIS Z 8901) inion-exchanged water with pH adjusted by sulfuric
acid, followed by observation for evidence of theadherence of stains. It can be seen that the block
treated with TB6644 coating (right) features lessadhered staining than the untreated block (left).
Without coatingWith TB6644
coating

Without TB6644G
application

With TB6644G
application

Photo 2. Protective effect of TB6644G against
iron powder

Photo 1. Results of stain prevention test using
TB664460° Mirror-surface gloss level

1-4. Weather-resistance of TB6644
Figure 2 shows the results of an accelerated
weathering test using TB6644.
A TB6644 coat was applied to a painted test steel
plate and used as a specimen for an accelerated
weathering test using a weathering machine. At allstages during the test, higher gloss is retained by the
TB6644-treated surface relative to the untreatedsurface. The difference in the inclinations of theplotted lines indicates that the loss of glossinessmay be slowed by nearly 25% through applicationof TB6644.
With coating
Without coating

Number of cycles

Figure 2. Results of weathering test using
TB6644
1-5.

Protection from Iron Powder with
TB6644G
The TB6644G is an aerosol version of TB6644
designed for aluminum wheels. Applying TB6644G
offers protection from staining for aluminum
wheels.

Photo 2 shows the results of an iron-powder
adhesion test using TB6644G. Significant degrees
of discoloration are evident in the untreatedaluminum test specimen (left) compared to thealuminum test specimen treated with TB6644G(right). This discoloration could neither be removed
by cleansing agents nor physical cleaning using acloth and was found to be the result of chemical
deterioration (electrolytic corrosion). The results
show that TB6644G is effective in preventing
corrosion of the aluminum wheel due to adhesion ofiron powder.
[Test method](1) A coat of TB6644G is applied to a test
specimen.
(2) 0.5 grams of iron power was sprinkled onto eachtest specimen.
(3) Approximately 1.8 grams of ion-exchanged
water was sprayed onto each test specimen.
(4) The test specimens were placed in athermostatic oven set to 80°C for 30 minutes.
(5) The test specimens were removed from the ovenand steps (3)-(4) (spraying of water and drying
at 80°C) were repeated a total of 10 times.
(6) The test specimens were left to cool to room
temperature, and the iron powder on the surface
was removed using an air blower(approx. 0.2 MPa).
Some car owners want to drive shiny cars, others
want to reduce the frequency at which they must
wash them. But regardless of the various motives ofdrivers, car owners will always want to protect their
beloved possessions from stains and deterioration.
The TB6644 series (Ultra Glass Coating) is acoating agent that responds to these desires.

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2.

Windshield Water Repellant

Since 1992, a dramatic increase has beenrecorded in the volume of products shipped that add
water-repellant properties to windshields for greater
visibility in rainy conditions. Initially, solutions
were rubbed onto the glass to form a hydrophobic
coat on the windshield surface, but later, productsthat were combined with windshield washer fluids
appeared, offering simultaneous application of thewater repellant with the washer fluid.
In fiscal year 2005, water repellants for glass
surfaces came in fourth place among top-grossing
chemical products for automobiles, after two typesof anti-freeze, three types of brake fluids, andwindshield washer fluids.3) Furthermore, as for thewindshield washer fluids that ranked in third place,
two types with water-repellant properties (with‘WC’ classification) were added to the list of
product types in the 2001 revision of JIS K 2398.
Thus, the trend in the incorporation ofwater-repellant properties in windshields is not apassing fad—these products are now recognized as
standard.
2-1. Water-repellence of Solid Surfaces
Liquids are retained at a certain angle (angle ofcontact) with the surface of a solid. The following
relationship holds when γS is the surface tension of
the solid, γL is the surface tension of the liquid, γSL
is the interfacial tension between the solid andliquid, and θ is the angle of contact (Young’s
equation):γS = γSL + γL·cosθ
According to Young’s equation, when the surface
tension of the liquid is constant, cosθ will decrease
with decreasing surface tension of the solid γS, i.e.,
the angle of contact will increase.
Since in practice it is difficult to measure thesurface tension of the solid γS, Zisman proposed theuse of the critical surface tension of solids (γC),
which is determined by measuring the angle ofcontact for solids using liquids of known surface
tension values and then by extrapolation to a zeroangle of contact (cosθ = 1).
Table 1 lists the critical surface tension of somesolids.4)

Table 1.

Surface structure and critical surface
tensionSurface structure

The approach of “surface free energies,” which isexpressed in units of energy per unit surface area
(J/m2), is often adopted for studying surface wetting.
On the other hand, the above surface tension isexpressed in units of force acting on unit length(N/m), and since energy = force × distance ( J =N·m), J/m2 = Nm/m2 = N/m, and so it may be seenthat the surface free energy and surface tension areequivalent as physical quantities.
2-2.

Application to Water Repellants for
Automobile Windshields
From Table 1, it may be seen that the introductionof fluorine compounds on the surface results in low
critical surface tension, and thereby enhances thewater repellency of the surface (which equates to anincreased angle of contact).
ThreeBond has taken advantage of this property
and now proposes a water-repellant surface-treating
agent for automobile windshields that contains
silane compounds featuring a perfluoroalkyl groupand organopolysiloxane.
Silane compounds having a perfluoroalkyl groupreact with a glass surface by the highly reactivefunctional group produced through hydrolysis,
which results in the incorporation of the fluorinecompound into the glass surface. This gives theglass surface high water-repellant properties(Figure 3).

Glass

Figure 3. Schematic image of incorporation ofa perfluoroalkyl silane compound
onto a glass surface

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2-3.

TB6550E — High-durability Water
Repellant for Glass
Some water repellant products for automobiles
require a process of mixing several fluids before
application to obtain the necessary durability of thewater-repellent effect. Product A by a rival company
is just such a product, with a product package
consisting of four types of solutions (a primer agent,water repellant fluid 1, water repellant fluid 2, and a
post-treatment agent). After application of theprimer agent, water repellant fluids 1 and 2 must be
mixed prior to their application, and the special
post-treatment agent must also be applied as afinishing coat. Thus, to obtain the desired
water-repellent coat, all four solutions must be used.
On the other hand, only two solutions are
required to apply TB6550E: a primer and the water
repellant fluid. There is no need for measuring or
mixing, and the process may be completed simply
by wiping the coat with the dry towel included in
the package.
Not only does the TB6550E-treated glass surface
display an extremely large angle of contact of over
100 degrees, but also offers greater durability ofeffectiveness, lasting far longer that that of similar
products from other companies.
Photo 3 shows photographs of water droplets on
TB6550E-treated and non-treated glass surfaces*taken during measurement of the angle of contact.

Untreated glass surface
Angle of contact = 15°

Treated glass surface
Angle of contact = 114°

Photo 3. Water repellency of TB6550E-treatedand untreated glass surface* The water repellency (angle of contact) of the glass
surface is subject to change depending on conditions
such as adhesion of dirt.

Figure 4 is a graph showing the relationshipbetween the number of polishes and angle ofcontact of the glass surfaces treated with TB6550E
and competing products after polishing the surface
with abrasive powder. It may be seen that the angleof contact for the TB6550E-treated glass surface isbetter retained compared to other products, andfrom the inclination of the plot, it may be concluded
that the TB6550E coat lasts 2.5 times longer thanother products.
Angle of contact (degrees)

The following section will introduce theTB6550E, a new glass water repellant for
automobile windshields offering high water
repellence and improved durability, now available
from ThreeBond.

Competing Product A
Competing Product B

Number of times polished

Figure 4. Durability of water repellency ofTB6550E
2-4. Ice Suppression Effect of TB6550E
The ability of silicone resins and fluorine resins toresist the accretion of snow and ice have beenstudied extensively, with practical applications in
the railway, communication, and energy fields.6)
In addition to greater visibility in rainy
conditions—for a safer driving environment—theTB6550E also prevents or suppresses theaccumulation of snow, ice, and frost on thewindshield. It is our hope that this feature willcontribute to the conservation of energy andultimately to the preservation of the global
environment by reducing the length of time people
need to warm up their cars to remove snow, etc.

3.

TB6641B Ultra Tire Coating Agent

The TB6641B is a protective coating agent for
tires that forms a reactive resin coating on the tiresurface. Unlike conventional silicone-oil type tire
wax, which applies oil to the tire surface, TB6641B
protects the tire from factors leading to degradationsuch as ultraviolet rays, allowing the tire to retain
its original black color for longer.
3-1. Tire Weathering
Since tires are constantly subjected to excessive
stress, one of the most important concerns naturally
involves the weathering of the rubber tire itself.
Some factors that promote weathering are:(1) Oxygen and ozone in atmosphere(2) UV radiation and direct sunlight(3) Other factors (rainwater, oil, heat, etc.)
All of these factors affect the tires on a daily basis.
Thus, the rubber compounds for tires always
contain anti-aging agents that protect the tires from5

such factors by suppressing the deterioration that
occurs when the tires are subjected to these factors(referred to as the “main chain scission reaction”) or
by seeping out to the surface to form a coating.
Since the anti-aging agents are brown, the tiresurface will also feature a brownish discoloration(hereafter referred to as browning).
In the browned condition, tires will have someadverse characteristics, such as:(1) appearing less attractive(2) soiling hands or clothes when touched

Durability PR(distributed bymanufacturer)

The browning may be eliminated by washing thetire surface, but since the tires will continue to be
subjected to the factors leading to degradation, they
will ultimately turn brown again.
3-2. Anti-weathering Mechanism of TB6441B
Figure 5 shows how the anti-weathering
mechanism of TB6641B works.
No coating

Anti-aging agent

Ultra tire coating

Tire

Tire

Tire (browned)

Tire

The anti-aging agent seeps out to thesurface to form a protective layer,
resulting in browning of the surface.

The TB6441B forms a protective layerand suppresses the seeping out of theanti-aging agent, thereby preventing
both browning and weathering.

Figure 5. Mechanism of weathering prevention
by TB6641B
Since TB6641B forms a protective coating for thetire in place of the anti-aging agents, the tires willremain free from browning and the tires will beprotected while retaining their black color.

Table 2. Comparison of coating durability data
TB6641B
Water-based
Tyre coat
Retains blacktire color foran extended
periodCompeting
Product A
Water-based
Tyre coat

Competing
Product B
Oil-based
Tyre coat

Competing
Product C
Oil-based
Tyre waxSuper
durability

Over 40 days

90 days××

Coating notretained

Coating notretained

Accelerated
weathering
test for 10
days

Coatingretained

Coatingretained

Observationin actualrunning
conditions

×

×

×

Retained after
6 months

Not retained
after 3months

Not retained
after 2months

Not retained
after 2months

Flexuralfatigue test
2.4 million
cyclesCoatingretained–––

3-3-1. Durability Test (Accelerated Weathering
Test)
An accelerated test to verify the durability of theTB6641B coat was performed using an accelerated
weathering
testmachine(specifically,a“xenon-arc-lamp weathering tester;” JIS B 7754).
TB6641B-treated and untreated areas were preparedon a test specimen, and the test specimen was left
exposed under the xenon-arc-lamp weathering tester
for a period of time before observing the differencein the weathering condition.
Based on a visual comparison with the results ofactual outdoor exposure tests, 10-day exposure
under the xenon-arc-lamp weathering tester wasconcluded to be approximately equivalent to a
six-month period of exposure in actual outdoor
conditions. Photo 4 presents the photographs of thetest results.
TB6641B

Competing
Product A

Competing
Product B

Competing
Product C

3-3. Durability of the TB6441B Coating
Table 2 presents the durability data for TB6641B
and competing products.

Photo 4. Tire surface after 10-day exposure
under the xenon-arc-lamp weathering
tester(Top: before test; bottom: after test)
The results show that the coating remained on thetires with TB6641B and with Competing Product A.
3-3-2. Durability Test (Flexural Fatigue Test)
As a coating durability test in light of the actual
running conditions of automobiles, evaluations
were made using a flexural fatigue tester (or the6

“De Mattia Flex Tester;” JIS K 6260). Photo 5
shows the tester in operation.

De Mattia flex tester

Beam moves vertically to bend the test
specimen

Photo 5. De Mattia flex tester
The flexibility fatigue test was repeated for 2.4
million cycles, assuming a travel distance permonth of 4,000 km. As with the xenon-arc-lamp
weathering tester, the test specimen was preparedassuming the following three cases.
(1) A new set of tires→ Partially masked and coated(2) A new set of tires with coating used for sometime
→ Partially masked and coated, thenexposed under the xenon-arc-lamp
weathering tester for 10 days
(3) Used set of tires→ The uncoated test specimen was exposed
under the xenon-arc-lamp weathering
tester for 10 days, then partially masked
and coated.
The results of testing are shown in Photo 6.
Test specimen 1

Test specimen 2

Test specimen 3

3-4. Plans for Future Development
The TB6641B allows tires to retain their
blackness through the formation of a coat. However,to meet diversifying consumer demands, we must
develop a tire coating that offers a “coated look,” in
addition to the “natural blackness” of the tire.
The demand for the “coated look” may besatisfied currently through the TB6640 and 6641
products, which contain silicone oil that leads to a
gloss, as well as by the “tire wax” that has been on
the market for some time. However, these products
have low durability, and so the “coated look” does
not last.
Figure 6 shows the difference in the mechanismsof the existing TB series products and the new one.
TB6641B Ultra Tire Coating
Strong coating is formed

TB6640, 6641, conventionaltire wax (silicone oil based)

Tire

Tire

Aging with time or by subjection to
rainwater

Tire

Tire

Coating gradually thinned but
the coating itself is durable

Coating lost immediately

Figure 6. Comparison of weathering
mechanisms to conventional TB
products
Since TB6641B utilizes a special resin having
membrane-forming properties, it can form a coatingoffering superior durability. Although the TB6640
and 6641 do not offer the same degree of durability,
the silicone oil contained in these products allows
them to offer a glossy look.
Figure 7 shows the correlation with existing TB
products.
With gloss(shiny)Uncharted territory

GlossinessSpecialized for
glossy look

Photo 6. Surface of tire after testing with De
Mattia flex tester(Top: before test; bottom: after test)
The test confirmed that in all cases (Cases 1-3),
coating was retained on the surface.

* Black as a new
set of tires

Balancingglossiness anddurability* technical issues

Specialized fordurability

No gloss
None

Durability

High

Figure 7. Correlation diagram of TB products
At present, ThreeBond is examining development
strategies to produce a glossy yet highly durable
coating based on the TB6641B, in the hopes ofpioneering this promising uncharted territory.

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4.

Conclusion

The three products introduced in the present report are amenities that will enhance your driving experience. In
recent years, media reports have suggested that new car sales have been in decline due to the development ofpublic transportation networks, increasing car maintenance costs, changing lifestyles of the younger generation,and diversifying values. In response to these trends, car dealers (i.e., automobile retailers) are beginning to inventa variety of ancillary services to promote sales. To meet the market demands of these challenging times,
ThreeBond has proposed and will continue to propose a lineup of chemical-product amenities that can be offered
as services with new car purchases and that will encourage consumers to take advantage of automobile safety
inspections and regular inspections. In the future as well, we will continue to place a high priority on thepreservation of the global environment in our development of resin products and strive to meet market demands
with our products.

References
1) Kozasa, T., et al.: Extended Abstracts of the 54th Spring Meeting of the Society of Applied Physics andRelated Societies, 54(2), p. 868 (2007)
2) Iwamoto Y. et al.: J. Eur. Ceram. Soc., 25 (2/3), p. 257 (2005)
3) Japan Auto Chemical Industry Association: Report of Survey on Status of Japan Auto Chemical Industry for
FY 2005 (2006)
4) W. A. Zisman: Ind. Eng. Chem., 55 (10), p. 19 (1963)
5) Patent # 2814259
6) For example, Saito, H. and Takazawa, H.: Journal of the Surface Finishing Society of Japan, 47 (7), p. 558(1996)
Kiyoshige Kono
Moritaka Takayama
Maki Takayama
Product Development Division,
Auto Aftermarket Department
R&D Group
ThreeBond Co., Ltd.

1456 Hazama-cho, Hachioji-shi, Tokyo 193-8533, Japan
Tel: 81-426-61-1333

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