Improving the Durability of Packaging Materials
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
CHEMICAL TREATMENT
Improving the Durability
of Packaging Materials
Behzad Bavarian, FNACE, On a global scale, the packaging protection and extends the shelf life of the
Anita Gregorian, Aline B. Avanessian, industry is an enormous economic products. Due to their effectiveness, flexi-
and Lisa Reiner, Manufacturing Systems bility, low cost, and ease of application, the
generator. The market value for the
Engineering and Management packaging technology finds its way into a
Department, California State packaging industry reached $1 trillion
in 2020; an increase from $839 billion wide range of products. Papers impreg-
University—Northridge, Northridge,
nated with volatile corrosion inhibitors
California, USA in 2015. The packaging industry rec-
(VCIs) have been used to protect sensitive
ognizes its responsibility in attaining a
Boris Miksic, FNACE, Cortec Corp., St. electronic components, metals in various
closed loop cycle for these materials forms, automotive parts, machinery,
Paul, Minnesota, USA
through the use of green corrosion engines, and tools. The demand for VCI
inhibitors. In this study, several papers packaging has significantly increased; the
impregnated with green inhibitors VCI packaging market is expected to
were investigated. Qualification tests exceed U.S. $680 million by 2023, compared
of these products were conducted to U.S. $480 million in 2015 and U.S. $540
using MIL-STD-3010C, including the million in 2018.
vapor-inhibiting ability before and Corrosion is an undesirable electro-
after the exhaustion test of inhibitor- chemical reaction for metals and alloys in
impregnated materials. Tests showed response to an aggressive environment. A
corrosion inhibitor is a chemical substance
very satisfactory results for some sam-
that, when added in small concentrations
ples before and after the exhaustion
P
to an environment, can minimize or decel-
tests. erate the corrosion process. Generally, an
efficient inhibitor is compatible with the
Packaging is an industry term for the environment, is economical to use, and
technolog y protecting any product produces the desired effect when present in
intended for storage and shipping. Statis- small concentrations. In the past, a protec-
tics indicate that the world market value tive oil coating was used to prevent corro-
for the packaging industry reached U.S. $1 sion during transport and storage. The use
trillion by 2020.1-4 During manufacturing, of oil for corrosion protection involves its
storage, and transport, humidity, salts, and disadvantages. The oil coating must be
other corrosive substances in the environ- removed before welding or painting. The
ment, as well as temperature fluctuations, removal of a protective oil coating also
can make metal parts more susceptible to requires solvents. The disposal of used sol-
corrosion. The likelihood of corrosion can vents has its own environmental restric-
be minimized either by controlling the tions. VCI packaging techniques facilitate
environment or by insulating the metal corrosion protection of metal parts in light
from the destructive surroundings using of the aforementioned complications.
suitable packaging materials containing VCI papers are highly effective and
corrosion inhibitors. Anticorrosion pack- common packaging materials for protect-
aging is an important trend in the packag- ing metals. They are cost-effective and easy
ing market because it provides optimum to use for both ferrous and non-ferrous
2 FEBRUARY 2021 WWW.MATERIALSPERFORMANCE.COM
TABLE 1. DIFFERENT VCI PAPERS EVALUATED IN THIS PROJECT1
VIA Test Pre- VIA Test Post- Wrapped in Paper
VCI Paper Paper Weight g/m2 Exhaustion Exhaustion Exhaustion (VIA)
VCI A 64.2 Passed Failed Passed
VCI B 64.3 Passed Failed Passed
VCI B+ coated with superhydrophobic 66.3 Passed Passed
VCI C 64.4 Passed Failed Passed
VCI C+ coated with superhydrophobic 68.1 Passed Passed
VCI D 63.5 Passed Failed Passed
VCI D+ coated with superhydrophobic 68.4 Passed Passed
VCI E 63.8 Passed Passed Passed
VCI E+ coated with superhydrophobic 67.6 Passed Passed
Kraft paper, base(A) 60.1
Standard 50-lb paper (3,000 ft [279 m ]) has ~60 to 64 g/m2 .
(A) 2 2
metals. These papers display good tensile into contact with the metal products within degrees, 3 while the range of the typical
strength and are mostly scratch/abrasion an enclosed space. Along with the corrosion roughness of uncoated paper is within the
resistant. VCI papers are environmentally protection, VCI packaging materials also range of 3 to 5 μm.7
friendly, allowing for biodegradability and act as moisture and dust barriers due to the The papers used in the experimental
sustainability by recycling into other types hydrophobic nature of non-polar groups in procedure are kraft papers, which consist of
of paper products, such as boxes and card- organic VCI inhibitors. VCIs protect both almost pure cellulose fibers. Cellulosic sur-
board. Furthermore, they are void of haz- accessible and hard-to-reach surfaces of the faces are comprised of hydrophilic fibers
ardous ingredients, such as nitrites, phos- metal from attack by corrosive species. VCI that make up a capillary system. Aspects,
phates, silicones, and chromates, or other packaging does not change the properties such as the capillarity and the hydrophilic
heavy metals. VCI-coated papers are of metal in any way and thereby, it has no nature of the cellulose fibers, increase the
intended for wrapping metals during ship- effect on the electrical or mechanical prop- absorbency of the kraft paper. Inherently,
ment, storage, and process operations. erties of the protected material. After the kraft paper displays a rough and inhomoge-
They are an effective means to protect dis- metal part is taken out of the package, the neous surface, which draws itself from the
similar metals against galvanic corrosion. VCI molecules volatize, and the metal is intertwining and flocculation of the fibers in
VCIs are bio-based organic chemical ready for immediate use, without any clean- the slurry state from the paper formation.
compounds with significant vapor pressure, ing required. This non-uniformity is seen on the order of
allowing vaporization of inhibiting mole- Paper-based packaging materials pos- the fiber dimensions. The surface is actually
cules and further adsorption onto metallic sess low barrier properties against oxygen an ill-defined boundary that depends on the
surfaces. VCI molecules move from the and water vapor penetration compared degree of fiber compaction and collapse.8
paper directly to the surface of metal, and with plastic-based packaging materials.5-6 Thus, the internal cavity of the cellulose
condense and adsorb onto the metal sur- In this study, the principles of superhydro- fibers, surface roughness, and the pore net-
face, forming an extremely thin molecular phobicity and the microstructure of kraft works are accountable for liquid or gaseous
protective layer of crystals over the metal paper were used to control the VCI diffu- permeability in the paper. Moisture can
surface. This thin layer effectively inhibits sion rate in the packaging papers. Superhy- migrate in the paper by a number of trans-
corrosion on the metal by preventing air, drophobicity can be created by embedding port mechanisms: vapor-phase diffusion in
moisture, salt, oxygen, and other corrosive nanoparticles or by creating porosity. Thus, the inter fiber pore space, Knudsen diffusion
elements from depositing on the metal sur- the inherent porosity of the papers was used in pores of diametersCHEMICAL TREATMENT
completion of the exhaustion test, the
paper was cut to 1 by 6 in (2.54 by 15.24 cm)
specimens for the VIA tests.
The corrosion behavior of carbon steel
(CS) (UNS G10100) samples was evaluated
per MIL-STD 3010C VIA test method and
subjected to VIA tests (one control sample,
three with impregnated paper, and six after
exhaustion tests; 10 total samples for each
VCI product). The VIA corrosion test
method provides for standard conditions
in a test jar of water-saturated warm air
without the presence of any corrosive spe-
cies. Prior to testing, all steel samples were
prepared by polishing with 240, 320, 400,
and 600 grit silicon carbide papers and a
final polish with 1 µm powder. The VIA
tests require: 1) sample conditioning for 20
h at 22 °C; 2) cooling cycle at 2 °C; 3) pre-
warming at 50 °C; and 4) followed by 3 h
more at 22 °C. After this process, the steel
samples were inspected for visible water
condensation and the surface of each was
FIGURE 1 Optical micrographs of samples after VIA test on VCI A post-exhaustion test; grade is 0;
visually examined by microscope to deter-
most pits are >300 μm.
mine its corrosion rating. The corrosion
criteria for rating steel specimens consist
Water flow in the fibrous layer moves along exposure to elevated temperature and con-
of grade 0 (worst case, heavy corrosion)
the fiber first and then fills the pore between trolled humidity (exhaustion tests). Visual
through grade 4 (no noticeable corrosion).
them. 10 The pores of the substrate were examination of the metal surface was done
For a valid VIA test, the control sample
impregnated through spray-coating of the using digital light microscopy and scan-
must have grade 0 (heavy corrosion). The
inhibiting solution. During the first spray, ning electron microscopy to assess the cor-
control samples consistently rated a grade
VCI compounds saturated the pores of the rosion grade for the steel specimen.
0 for all VIA tests; therefore, the test was
cellulose fiber, both inter and intra. The VCI A and B are two impregnated wrap
valid. RH and the temperature of each test
purpose of the second spray (superhydro- papers commercially available. Additional
jar were monitored by sensors and data log-
phobic coating) allowed for the lowering of VCI-coated papers were prepared by apply-
ging software. Samples subjected to the
surface energy by altering the surface chem- ing VCI C, D, and E on natural kraft paper
exhaustion test paper were inspected to
istry through silane derivatives, while fur- (standard 50-lb kraft paper has a weight of
ensure none had any surface pits that
ther micro and sub-micro roughness was ~60 to 64 g/m 2) and drying the coated
exceeded 300 mm in diameter.
introduced. The increase of roughness adds papers at 40 °C. One set of prepared VCI-
to the tortuosity of both gaseous and liquid coated papers was sprayed with hydropho-
materials. Hence, the moisture migration bic moisture-repelling barrier coating after Results
occurring by diffusion of water vapor drying. Table 1 lists the different coated The VIA corrosion grading per TM-208
through the void spaces and in condensed papers that were investigated. The vapor of these samples are summarized in Table
form through the fiber cell walls must now inhibiting ability of these VCI-impregnated 1. These tests results create concerns over
travel an increased path length.7,11 It is evi- wrap papers were investigated by using 2 by the feasibility of the exhaustion test crite-
dent from the results that the micro-rough- 8 in (5.08 by 20.32 cm) paper samples for ria. Corrosion behavior of CS in the pres-
ness arising from the position of the fibers the exhaustion tests. The exhaustion tests ence of VCI-coated packaging papers is
in the network followed with a hydrophobi- were conducted at 60 °C for 12 days as per shown in Figures 1 and 2.
zation treatment hindered the vapor phase MIL-STD-3010C 13 Test Method 4031 for Papers coated with the superhydropho-
transport through the void spaces by "Exhaustion Test of Packaging Materials." bic coating showed very promising results
increasing the tortuous paths.12 During this test, air was maintained at and coated samples passed the post-
~50% relative humidity (RH) and pumped exhaustion VIA with gradings of 3 to 4.
Experimental Procedure at a rate of ~100 cm3/min into the test tube. None of the superhydrophobic coated
The inhibiting ability of VCI coatings To achieve the proper RH, air passed papers showed any surface pitting exceed-
was evaluated by electrochemical polariza- through ~26% by volume mixture of glyc- ing 300 μm after exhaustion VIA tests.
tion tests and vapor inhibiting ability (VIA) erin/distilled water. Four exhaustion tests Two commercially available papers
tests that were conducted before and after were conducted on each sample and after (VCI A and VCI B) failed the post exhaus-
4 FEBRUARY 2021 WWW.MATERIALSPERFORMANCE.COMImproving the Durability of Packaging Materials
7 A. Anzar, et al., “Online Surface Roughness
Characterization of Paper and Paperboard
Using a Line of Light Triangulation Tech-
nique,” Nordic Pulp & Paper Research J. 27, 3
(2012): pp. 662-670.
8 R.E. Popil, Physical Testing of Paper (Shaw-
bury, United Kingdom: Smithers Rapra Tech-
nology, 2017), pp. 17-27.
9 H. Gupta, S.G. Chatterjee, “Parallel Diffusion
of Moisture in Paper. Part 1: Steady-State
Conditions,” Industrial & Engineering Chemis-
try Research 42, 25 (2003): pp. 6,582-6,592.
10 H. Aslannejad, S.M. Hassanizadeh, “Study of
FIGURE 2 VIA tests comparison of VCI E corrosion behaviors using superhydrophobic coating. Hydraulic Properties of Uncoated Paper :
Image Analysis and Pore-Scale Modeling,”
Transport in Porous Media 120, 1 (2017): pp.
tion VIA tests, creating concerns about the tests and steel samples achieved grade 4. 67-81.
exhaustion test criteria. One possible expla- Applying superhydrophobic coating 11 S. Rivero, J. Lecot, A. Pinotti, “Impregnation
nation for the failure is the exhaustion test showed a satisfactory performance for all of Kraft Paper Support with Polylactic Acid
Multilayers,” Advanced Materials Letters 8, 6
conditions; 60 °C for 12 days while circulat- impregnated papers. Two commercially
(2017): pp. 741-751.
ing air at 50% RH and a flow rate of 100 cm3/ available papers failed the post exhaustion 12 S.T. Yohe, Y.L. Colson, M.W. Grinstaff, “Super-
min can result in the loss of the VCI compo- VIA tests. This created concern over the hydrophobic Materials for Tunable Drug
nent on the wrap paper. Therefore, follow- feasibility of the exhaustion test criteria. Release: Using Displacement of Air to Con-
ing exhaustion tests, the VCI quantity is not Conducting the exhaustion tests on the trol Delivery Rates,” J. of The American Chem-
ical Society 134, 4 (2012): pp. 2,016 -2,019.
sufficient to protect the steel sample during wrapped steel samples with VCI packaging
13 MIL-STD-3010C, "Military Standard: Test
the VIA tests. The other issue is the mecha- materials and subjecting those samples to Procedures for Packaging Materials" (Wash-
nism of VCI surface adsorption. When the the VIA tests demonstrated satisfactory ington, DC: U.S. Department of Defense,
VCI adsorbed onto the steel surface, its results of grade 3 to 4. Therefore, the MIL- 2013).
hydrophobic nature does not allow wetting STD 3010C VIA and exhaustion test method
BEHZAD BAVARIAN, FNACE, is a professor in
of the surface that results in better corro- might need to be re-evaluated and the the Manufacturing Systems Engineering and
sion protection. The exhaustion test on the exhaustion cycle procedure modified. Management Department at California State
wrapping materials removes (depletes) the University—Northridge (MSEM-CSUN), North-
ridge, California, USA, email: bavarian@csun.
protective VCI compounds and results in References
edu. Bavarian is a NACE Fellow, Mory Ejabat
unacceptable VIA grading. 1 B. Bavarian, et al., “Improving the Durability
Endowed chair, and director of the W.M. Keck
It is a more realistic approach to con- of Packaging Materials Using Vapor Phase
Advanced Materials Laboratory. Bavarian
Corrosion Inhibitors,” C2020, paper no. 14294 earned his Ph.D. in metallurgical engineering
duct the exhaustion tests on the wrapped (Houston, Texas: NACE International, 2020). at The Ohio State University in 1980. He has
steel samples with VCI packaging materials 2 “Packaging Material Outlooks—Towards a $1 been a member of NACE International for 36
and subject those samples to the VIA tests. Trillion Milestone in 2020,” Smithers Pira years.
These tests demonstrate whether the VCI- Market Report, December 17, 2017, https://
adsorbed compound can maintain its www.smitherspira.com/resources/2016/feb- ANITA GREGORIAN is a graduate research
ruary/global-packaging-material-outlooks. assistant at MSEM-CSUN, email: anita.
attachment to the metal surface during the 3 H. Teisala, M. Tuominen, J. Kuusipalo, gregorian.86@my.csun.edu.
exhaustion tests, protecting steel samples “Superhydrophobic Coatings on Cellulose-
against corrosion. By modifying the Based Materials,” Advanced Materials Inter- ALINE B. AVANESSIAN is a research associate
exhaustion tests to include the steel sam- faces 1, 1 (2013): pp. 1-20. and lecturer at MSEM-CSUN, email: aline.
4 “Corrosion Protection Packaging Market— balasanavanessian@csun.edu.
ples in the test chamber (wrapping steel
Global Industry Analysis, Size, Share,
samples with the VCI impregnated papers LISA REINER is a research associate and lec-
Growth, Trends and Forecast 2017-2025,”
during the exhaustion cycle), VIA tests Transparency Market Research, https:// turer at MSEM-CSUN, email: lisa.reiner@csun.
showed a very satisfactory performance for www.transparencymarketresearch.com/ edu.
VCI A, VCI B, VCI C, VCI D, and VCI E, with corrosion-protection-packaging-market.
BORIS MIKSIC, FNACE, is CEO at Cortec
a grading of 3 to 4. This modification in the html (Dec. 22, 2020).
Corp., St. Paul, Minnesota, USA, email: Boris@
5 B. Bavarian, et al., “Application of Vapor
exhaustion cycle allowed the VCI molecule cortecvci.com. Miksic earned an M.Sc. from
Phase Corrosion Inhibitors for Contami-
to be absorbed on the steel surfaces; the University of Zagreb. He holds 44 U.S.
nated Environments,” CORROSION 2019, patents and 25 foreign patents, and is the
improved corrosion performance was seen paper no. 12772 (Houston, Texas: NACE, author of three books on corrosion, and over
for these VIA tests. 2019). 100 peer-reviewed technical papers, including
6 S. Shankar, R . Jong-Whan, “Effects of articles published in MP. He was awarded the
Poly(Butylene Adipate-Co-Terephthalate) NACE Distinguished Organization and Speller
Conclusions Coating on the Water Resistant, Mechanical, Awards, Ernst and Young Master Entrepre-
In summary, VCI-impregnated papers and Antibacterial Properties of Kraft Paper,” neur of the Year Award, and is Honorary Con-
showed satisfactory corrosion protection Progress in Organic Coatings 123 (2018): pp. sul General of Croatia to USA. Miksic has been
153-159. a member of NACE for over 45 years.
in the VIA test method after exhaustion
MATERIALS PERFORMANCE: VOL. 60, NO. 2 FEBRUARY 2021 5You can also read
