Chemical Resistance

Organic solvents like toluene can immediately assault ABS resin, but even less harsh chemicals, which might show no immediate visible effect, can induce cracks in plastic parts over extended contact periods. This phenomenon, known as Environmental Stress Cracking (or commonly, chemical cracking), transpires when a chemical slowly infiltrates the spaces between molecular chains on the resin surface under stress, initiating microscopic cracks (microcrackzes) and ultimately, destruction.

Notably, environmental stress cracks might result in the material abruptly cracking with no apparent whitening or plastic deformation on the fractured part'’s surface.

In contrast, strength or fatigue fractures typically exhibit a significantly whitened fracture surface. This whitening is a consequence of the rubber component within the resin stretching due to stress-induced deformation, causing surface roughness and light reflection. In environmental stress cracks, the rubber component erodes gradually through prolonged chemical exposure, so by the time of failure, scarcely any rubber persists around the fractured part, rendering the fracture surface unwhitened and seemingly cleanly cut.

The occurrence of environmental stress cracking, as noted, is due to the simultaneous existence of “chemical contact” and “stress”. Therefore, mitigation approaches necessitate the elimination or mitigation of one or both of these elements.

(Interestingly, environmental stress cracks can frequently occur in parts that are not subject to significant stress. This is primarily attributable to residual stress from the resin, which cools and contracts during molding, lingering in the product. To alleviate this, it is essential to mold parts in a manner that retains as minimal internal stress as possible by fine-tuning the molding conditions.)

As shown in the following table, various chemicals can cause environmental stress cracks (attacks) in ABS. For example, even in the ”fats and oils“ category, attack intensities vary between animal and sources, with vegetable the latter normally prevailing.
Environmental stress cracking also occurs in non-ABS resins, but the chemical resistance of the resin to these chemicals is dictated by the resin composition and the composition of the chemicals involved, as well as the amount of distortion in the molded product.

The method for evaluating the chemical resistance of ABS resin to common substances is as follows:1/4 ellipse method is used to evaluate the chemical resistance of ABS resin to common substances.It is determined by the amount of strain (critical strain value) at which cracks occur due to environmental stress and the amount of strain caused by chemical applications.
The evaluation results for several of our representative resins are shown below.

How to view the results

Based on the critical strain value of the test results, guidelines for actual use are shown below.
This guideline is only an estimate of whitening and cracks. during actual use from the results of the test piece.
Please confirm via a practical test at your company.

Critical strain value

0.3% or less :High potential for cracking due to slight stress during product assembly and transportation.
0.3-0.7% : Whitening and cracking may occur due to contact with chemicals. Particular care needed when exposed to strong stress.
0.7% or more : Usable. Low risk of cracks or similar due to contact with chemicals.

January

Techno UMG Chemical resistance of general ABS resin

Drug name	Critical strain (%)	Drug name	Critical strain (%)	Drug name	Critical strain (%)
10% hydrochloric acid	0.7 or more	hair spray	0.22	family	0.45
10% caustic soda	0.7 or more	hair tonic	0.31	Mama lemon	0.7 or more
Ethyl alcohol	0.25	Cleansing cream	0.45	strong look	0.2 or less
Gasoline	0.2 or less	Hair tonic	0.56	my pet	0.31
Kerosene	0.5	fragrance bouquet	0.25	mama royal	0.5
silicon oil	0.7 or more	forest bathing	0.24	charmy green	0.42
silicon grease	0.7 or more	Freon R-11	0.68	toilet Magic ring	0.29
Salad oil	0.56	anti-rust	0.6	toilet look	0.7 or more
Sesame oil	0.63	Cutting oil	0.3	Quickle	0.7
butter	0.62	earth aerosol	0.48
Vinegar	0.7 or more	ink	0.5

Techno UMG Chemical resistance of flame-retardant ABS resin

Drug name	Critical strain (%)
Drug name	F5330	F1350	F5350	F5451
10% hydrochloric acid	0.7 or more	0.7 or more	0.7 or more	0.7 or more
Ethyl alcohol	0.25	0.25	0.25	0.25
Kerosene	0.4	0.5	0.4	0.4
Magic ring	0.3	0.3	0.3	0.3
Mama lemon	0.7 or more	0.7 or more	0.7 or more	0.7 or more
strong look	0.2 or less	0.2 or less	0.2 or less	0.2 or less
Sesame oil	0.5	0.6	0.5	0.5
Molykote Grease E	0.7 or more	0.7 or more	0.7 or more	0.7 or more
Cutting oil	0.3	0.3	0.3	0.3

Chemical resistance of Techno UMG PC/ABS resin (CK10,20,50)

Drug name	CK10,20		CK50
Drug name	Appearance change	Critical strain value	Appearance	Critical strain value
10% caustic soda	Whitening	0.7 or more	Whitening	0.7 or more
30% sulfuric acid	none	0.7 or more	none	0.7 or more
10% hydrochloric acid	none	0.7 or more	none	0.7 or more
Ethyl alcohol	none	0.7 or more	none	0.7 or more
Methyl alcohol	Slightly bleached	0.7 or more	Slightly bleached	0.7 or more
Acetone	dissolution	0.2 or less	dissolution	0.2 or less
Toluene	dissolution	0.2 or less	dissolution	0.2 or less
Carbon tetrachloride	swelling	0.5	Whitening	0.3
White kerosene	none	0.7 or more	none	0.7 or more
Engine oil	none	0.7 or more	none	0.7 or more
Brake oil	dissolution	0.2 or less	dissolution	0.2 or less

Techno UMG Flame retardant PC/ABS resin (CKF50) chemical resistance

Drug name	CKF50
Drug name	Appearance change	Critical strain value
10% caustic soda	Whitening	0.7 or more
30% sulfuric acid	none	0.7 or more
10% hydrochloric acid	none	0.7 or more
Ethyl alcohol	none	0.7 or more
Methyl alcohol	none	0.7 or more
Acetone	dissolution	0.2 or less
Toluene	dissolution	0.2 or less
Carbon tetrachloride	swelling	0.3
White kerosene	none	0.7 or more
Engine oil	none	0.7 or more
Brake oil	dissolution	0.2 or less

About the chemical resistance test method

Test method

Techno (formerly Mitsubishi Chemical) bending form method (1/4 ellipse method)
23℃, 17 hours, test piece 2mm press sheet

This testing procedure employs Bergen’s quarter ellipse method. A plate-shaped specimen is secured in a jig with a gradually increasing curvature towards the tip, after which chemicals are applied. The influence of the chemicals is assessed based on the location of crack initiation.
Since the bending stress intensifies at the jig’s tip, if a crack does not form, or forms near the tip, it indicates commendable chemical resistance (= it will not fracture unless subjected to substantial stress). Conversely, if a crack forms closer to the root, it suggests a potent impact from the chemical.

Test method based on Bergen's quarter ellipse method