Issued January 1, 2000

The Fourth-Generation Locking Agent for Screws:
Gum-type BondIntroduction
A variety of screws or bolts are used for connections in various industries. Loosened screws can cause
serious accidents and so many kinds of locking methods are available.
Three Bond has offered three generations of screw-locking agents, all of which are widely used in ourcustomers’ production facilities to improve assembly efficiency:
ThreeBond 1400 series - first generation: volatile solvent screw-locking agent.
ThreeBond 1300 series - second generation: anaerobic screw sealant.
ThreeBond 2400 series - third generation: microencapsulated screw-locking agent.
All have the basic bonding function along with specific features.
Recent accidents, such as the collapse of a steel tower or the fall of a bolt from a large structure, haveshown that anti-loosening is required not only for the manufacturing and assembly lines but also forlarge-diameter bolts. The requirements for the agent differ according to the environment used, such as
working in rain in open-air environment, working under water, or repairing automobiles. Furthermore,
improvements are expected for the sealing of pipe joints for ease of assembly, in addition to the original
purpose of locking the threads.
In June 1999, Three Bond released the fourth-generation locking agent, a gum-type bond for screws,
to meet these market demands, which differ from the requirements from the assembly line.
This issue introduces the gum-type bond and describes its excellent screw-locking and sealing functions and workability.
ThreeBond is abbreviated as TB hereafter.

ContentsIntroduction ········································
1. Gum-type bond TB1450B and 1450C ·1-1. Outline ····································
1-2. Characteristics························
1-3. Curing mechanism of gum-type bond ·2. Improving the sealing effect ··········
2-1. Methods for sealing screw threads ·2-2. Improving retention in the thread clearance ·3. Physical property of the gum-type bond ·3-1. Fixing strength by material ······
3-2. Fixing strength by size············
3-3. Fixing strength at different temperatures ·1222333344443-4. Resistance of fixing strengthand sealing effect to heat ······· 43-5. Fixing strength and sealing effectagainst chemicals··················· 53-6. Sealing test with various bolts
and plugs································ 53-7. Fixing strength with various
thread precisions ···················· 54. Procedures for applying gum-bond · 65. Notes ············································· 76. Conclusion····································· 811. Gum-type bond TB1450B and 1450C
1-1. Outline
Gum-type bonds, TB1450B and 1450C, are environment-friendly, solvent-free agents for locking
screws.
The main characteristic of this kind of bond is its
gum-like (rubber-like) form, a state between liquidand solid. This adhesive can be applied by windingaround the object, which was not possible with liquidadhesives (Photo 1).
Also it contains microcapsules, which break when
the screws are fastened and thus help to cure and lockquickly.

TypeColor

TB1450B
TB1450CBlue
OrangePhoto 1. Gum-type bondGeneral guideline forhandling temperature*
5 ~ 30˚C
25 ~ 50˚C

Content
100 g
100 g

* Use one of the two types, depending on the temperature of handling environment, for easier squeezing.

1-2. Characteristics
The gum-type bond has the following characteristics:(1) It is an environment-friendly, solvent-freereactive locking agent for screws.
(2) It can be applied by winding it around thescrews.
(3) It has excellent filling into thread clearance,
offering good sealing.
(4) An excess can be removed easily (Fig. 1).
Solvent was necessary to remove excess liquidadhesive, but gum-like adhesive can be removedeasily.
(5) It locks any metallic objects.
When the screws are fastened, the micro-capsules
break, releasing the curing agent. The bond curesand locks screws of any metals.
(6) Micro capsules offer excellent preservationof their contents. In our tests, the contents
have lasted for two years at room temperature.

Excess resin
after fastening

Remove excess
resin by rolling it
round a stickFig. 1. Removal of excess gum-type bond2

1-3. Curing mechanism of gum-type bondGum-type bond is composed of gum-likemethacrylate ester that contains a curing catalyst,
and capsules of curing agent.
When the screw is clamped, the shearing force
breaks the capsules, releasing the curing agent for
hardening (Fig. 2).
If the screw is not fastened, the capsules do notbreak, and so no curing occurs.
So curing occurs only when the screw is clamped.

c) Starting reaction
and hardening
Hardenerc)

Reaction andhardeningb)

Spreadinghardenera)

Breaking capsuleby screwing

Hardener

2. Improving the sealing effectMethacrylate
If a sealant has good resistance to deterioration
Hardener capsulecaused by chemical effects or aging, its effectivenessFig. 2. Hardening mechanism
depends on whether it is densely filled in the clearance between the screw threads and whether it is well bonded to the threads.
In simple words, good sealing can be obtained by filling the sealant in the thread clearance densely and byimproving the strength of the bond between sealant and threads.
2-1. Methods for sealing screw threads
Roughly speaking, there are two basic methods for sealing a screw, as shown in Fig. 3. One is to fill the thread
clearance with nonreactive sealants, and the other is to bond with reactive agents, such as the anaerobic sealant or
the microcapsule thread-locking process (called “the MEC process” hereafter). The latter actually provides sealing not only by adhesion but also by filling.

Fig. 3. Sealing conditions of screws

Liquid bondGum-type bond

Good
Nut

Restoring force
by gum elasticity

Fillability toclearance

2-2. Improving retention in the thread clearance
The gum-type bond, as Fig. 4 shows, fills and stays
in the thread clearance with its elasticity, so is noteasily squeezed out as regular liquid adhesive is.
So it gives excellent sealing.

Bad
Nut

Extruding of resin,and dropping if low viscosity

Fig. 4. Difference of retention in the threadclearance

33. Physical property of the gum-type bond
3-1. Fixing strength by material
The gum-type bond provides fixing strength
regardless of the type of metallic materials, in thesame way as the MEC process.
Tested bolt : JIS Class2 M10 × P1.5
■ Fixing strength for various materials
Plain steel (N·m)
45

Aluminum

Tested bolt : JIS Class2 bigger than M4■ Fixing strength for various sizes
M4 (N·m)
2.52300
1.5200 1

Plated withzinc chromate

35M24(Plated with 400 300 200
melted zinc)

15

Plated withunichromate

5100150

Dyed black

3-3. Fixing strength at different temperatures
The break loose torque of the bond was measured
at different temperatures after reaction curing on abolt. The gum-type bond maintains its fixing
strength at 150˚C (Fig. 5 and 6).
Note: At 180˚C, the recorded break loose torque islower than the fastening torque, but the bonding
strength recovers when the temperature decreases.
Fastening after applying gum-type bondFastening torque : 29.4 N·m

10620
10 1540120

Fixing strength
Fastening torque

SUS3048480

M16
Plated with nickel

M6M24(Plain steel) 400

25Brass3-2. Fixing strength by size
Gum-type bond has enough fixing strength for M4size bolts, but it is best suited for M8 size or bigger
because it is easier to apply to bigger bolts.

M142040306080

M12M840 M10Fixing strength
Fastening torque

Break loose torque (N·m)
403530JIS Class 2 copper nut platedwith zinc chromate
Flat washer
JIS Class 2 copper bolt platedwith zinc chromate, M10 × P1.5

Fig. 5. Tested bolt

25050
100
150
200
Measurement temp. of break loose torque (°C)

Fig. 6. Break loose torque at various temperature3-4. Resistance of fixing strength and sealing effect to heat
In heat deterioration tests, screws sealed with gum bond were subjected to temperatures of 100˚C and 150˚C for
30 days. As the results show (Figs 7-9, Table 1), neither fixing strength nor sealing effect deteriorated.
A leakage test was carried out at pressures
up to 10 MPa, using the apparatus below.
a-part

Turbineoil No.1

Clamping after applying
gum-type bond
Clamping torque 29.4 N·m
Tested bolt

Compression

Fig. 7. Total view of sealing test

4JIS Class 2 steel bolt plated with zinc chromate
M10 × P1.5 × 20

Flat washer
Aluminum
A5052P
10mm

Seal medium(turbine oil No.1)

Fig. 8. Enlarged view of a-part (in Fig. 7)

Table 1. Sealing effect after thermal
degradation test

Sealing effect Initial (0 day) 10 days

Break loose torque (N·m)

30 days

10MPa
10MPa
10MPa
Passed the Passed the Passed thesealing test sealing test sealing test

40100˚C

30150˚C

10MPa
10MPa
10MPa
Passed the Passed the Passed thesealing test sealing test sealing test

35100°C
150°C

2503-5. Fixing strength and sealing effect against
chemicals
To simulate an automotive environment, a test
piece was immersed in engine-cooling water andengine oil for 30 days.
No deterioration was observed in either fixing
strength or sealing effect (Table 2, Fig. 10).
Table 2. Sealing effect after chemical
immersion

30354040353010MPa
10MPa
Passed the Passed thesealing test sealing test

2510MPaEngine oil
Immersion tem- Passed theperature120˚C sealing test

10MPa
10MPa
Passed the Passed thesealing test sealing test

3-7. Fixing strength with various thread precisions
The fixing strength was measured using internal
threads of JIS Classes 1 to 3 (Fig. 12), for variationsin the gap at the external thread valley. The gumtype bond showed stable fixing strength regardless ofthe precision of the internal threads.

20
25
Elapsed days

Break loose torque (N·m)

30 days3-6. Sealing test with various bolts and plugs
Sealing tests were carried out with various bolts
and plugs. The gum-type bond exhibited excellent
sealing in all of the tests (Table 3).

15Fig. 9. Fixing strength after thermal
degradation testEngine coolant
10MPa(50%aq)
Passed theImmersion temperature100˚C sealing test

Sealing effect Initial (0 day) 10 days

5Engine coolant (50%aq)
Engine oil

0515202530
Immersed days

3540Fig. 10. Fixing strength after chemical
immersion
Table 3. Sealing effect for various bolts andplugs

Tested bolts and plugs Result of the sealing test
10MPa Passed the sealing test
M10 bolt
10MPa Passed the sealing test
PT3/8 plug
10MPa Passed the sealing test
PT1/2 plug
10MPa Passed the sealing test
PT3/4 plug
* After 24 hours hardening at 25˚C, we checked forleaks by increasing pressure 1 MPa/min up to 10MPa.
Break loose torque (N·m)

50403020100Class1Class2Class3
Accuracy of internal thread (JIS classes)

Fig. 11. Condition of valley gap

Fig. 12. Break loose torque for various
screw accuracies

54. Procedures for applying gum-bondDegrease the threads
Using a cloth, remove oil and machining
debris from the threads of bolts andpipes. Then degrease the threads withsolvent.

Wind the gum-type bondaround the threads
Squeeze the bond out of the tube. Pulling
gently, wind the bond around the threads
2 to 3 times.

Fastening
Fasten the nut (or socket).

Process is complete

65. Notes
a. Excessive sealant
The gum-type bond cures only when a screw or abolt is clamped. Any excessive sealant does not cure,
except where pressure is added, as at the seating faceof a bolt.
If excess sealant remains uncured on internal
threads, (such as where pipes are joined), it mightflow and clog the filters.
To prevent excess sealant from remaining on internal threads, leave the first one or two of the external
threads free of locking agent.

Best position forapplying bondPosition for clamping
the nutFig. 13. Best position for applying bondb. Degreasing
If oil or water is present on the thread, the gum-type bond will not adhere. Make sure that the threads aredegreased sufficiently.
c. Thread clearance
When the clearance between the internal and external threads is too large, the microcapsules will not break, andtherefore the gum-type bond will not cure.
This results in curing failure. Check the thread clearance before applying sealant.
d. Adherend materials
Some plastics and rubbers change their properties when in contact with adhesives. Check the possible influences, such as cracks, dissolution, swelling, and whitening, beforehand. Do not use the bond for wood; it will notcure.

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6. Conclusion
By combining basic Three Bond technologies-microencapsulation, acrylic adhesives, and sealing
methods--the gum-type bond has been developed. It
supports new applications, easier handling, andimproved performance.

Besides expanding the grades and features to offer
a wider range of applications, we will continue todevelop new screw sealing products, improving theanti-loosening and sealing functions, and also supporting the environment and recycling concernedfeatures.

Three Bond Co., Ltd.
Research and Development Division

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

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