GRC 211 ch7-8

True or false: When print stay outdoors for a long time, the colors on the print fade away. This is referred to as ink's color strength

false Color strength measures how much the ink is pigment concentrated, as measured by bleach test

True or false: water pick-up describes how much water can be blended into water-based inks

false Water pick-up describes how much water can blend into oil-based offset inks

True or false: Water-based ink formulation doesn't contain VOC

false (contains less than 20% VOC)

True or false: wax can be used to improve ink film gloss

false: wax increases rub resistance and decreases gloss

property of gravure ink

fluid

ink vehicles

fluid portion of ink that carries pigments

paperboard comparison

for foldability and creasebility, SBS is the highest (then SBB then FBB)

rub resistance

force of friction

inorganic color pigments

inexpensive, good opacity, good light fastness 1. iron oxide, chrome yellow, zinc yellow, iron blue 2. metallic inks (gold from bronze powder, silver from aluminum)

pigments

insoluble in water or organic solvents

tack

resistance of film breaking (stickiness) only applies to offset ink

what type of ink is short ink?

screen printing ink

pseudoplastic

shear thinning

dyes

soluble, brilliant color, low fade and humidity resistance

solid bleached sulfate (SBS)

strongest paper board made of pure chemical pulp excellent printing (high smoothness and brightness) e.g. perfumes, cosmetics, pharmaceuticals, frozen foods

laminated paperboard properties

surface properties (smooth from wax, high barrier) strength properties (puncture, tear) stiffness hydroscopic properties (moisture barrier) polymer adhesion odor neutrality

breakage

tack on low basis weight paper

picking

tack on low surface strength paper

water pick-up value

the amount of water picked by ink only applies to offset ink

ink solvents

dissolve resin, provide a mean of drying 1. VOCs, fluid inks, paste inks

Which of the following ingredients is not used for making ink? a) wax b) plasticizer c) vehicles d) dyes e) fillers

e) fillers

eco-solvent drying mechanism

evaporation

solvent based drying mechanism

evaporation

water based (dye or pigmented) drying mechanism

evaporation and absorption

lightfastness

fade resistance

True or false: thixotropic means ink viscosity increases under agitation like stirring or mixing

false

flatness of corrugated board

(aka warping) thin boards are more prone to warm than thick boards; caused commonly from moisture in environment

colorant requirements

1. color 2. transparency 3. light resistance (outdoor usage) chemical (cosmetics) heat (coffee mugs) oil (food package) rub (wraps)

ink properties and performance

1. drying (boiling point) 2. tack 3. flow (paste or fluid)

working properties of ink

1. how well ink transfers onto substrates 2. pigment dispersion 3. pigment particle size (color strength, hiding power, saturation, gloss, dispersion)

ink oils

1. offset inks: oil-based 2. nondrying oils: mineral oils 3. drying oils: petroleum, linseed, or tung dry by oxidation

ink additives

1. plasticizer increases gloss, adhesion, and ink film flexibility (e.g. cracks on t-shirt) 2. wax improves rub resistance but reduces gloss

problems related to ink drying rate

1. too slow 2. too fast (ink dries in gravure/flexo cells)

white pigments

1. white high opacity 2. opaque ink

organic color pigments

CMY (process colors with high transparent and high fading resistance)

highest strength of corrugated cardboard

SBS

Which of the following statements about ink opacity is NOT true? a) process inks could be transparent or opaque depends on the application b) ink opacity describes the hiding power of ink films c) metallic inks are opaque inks that have high opacity

a) process inks could be transparent or opaque depends on the application Process inks are transparent inks

The newspaper inks often smudge off onto fingers because... (more than one) a) newspaper ink contains mineral oils which dries by absorption b) it is not completely dry c) it is not fully evaporated d) it is absorbed into newspaper

a), b), d) Inks are absorbed into paper and are not allowed enough drying time, so they are partially wet when delivered

thixotropic

ability of a gel to become more fluid (lower viscosity) with increasing shear and then viscosity increases when shearing stops

viscosity

ability of resisting flow high viscosity: paste ink low viscosity: fluid ink

ink length

ability to be stretched before snapping

oil based drying mechanism

absorption and oxidation

drying mechanisms

absorption, evaporation, oxidation

The best way to improve print quality on rough cardboard is to

apply coating

drying rate is affected by...

area of coverage, relative humidity, ink film thickness, paper absorbency

ink resins

bond the pigments to one another - correct resins determined by intended substrate, printing process

Which of the following statements about ink tack is NOT correct? a) print higher tack ink first, lower tack ink last for better trapping b) high tack ink printed on paper with low surface strength will cause picking c) ink tack relates to offset and screen inks d) ink tack describes how viscous/thick ink is

c), d) Ink tack describes how sticky ink is, not how viscous/thick it is.

folding box board (FBB)

coating, bleached chemical pulp, mechanical pulp, unbleached chemical pulp (good stiffness) e.g. dry foods, tea and coffee, baked goods, etc.

white lined chipboard (WLC)

coating, pulp or white recycled fiber, recycled fiber, mixed recycled fiber, back coating etc. boxes, display outers, food products

basic ingredients of inks

colorant, vehicle, solvent, additives

corrugated board

composed of flutes (waves) and flat (liner) single face: one flute, one liner single wall (double face): one flute, two liners double wall: two flutes, three liners

grain direction of paperboard products (cup)

cracks at the rim of the cup: against the grain grain direction should be perpendicular with height

reel curl

curling from mechanical/physical (bending) force - always curls toward to machine direction - curl side faces the reel at end of paper machine

Which of the following inks are formulated with organic pigment? a) black ink b) golden or silver ink c) white ink d) magenta ink

d)

what type of ink is long ink?

offset printing ink

Which ink were used to print on a brown cardboard box? a) transparent b) opaque

opaque inks (substrate is nonwhite)

Inks can dry by...

oxidation, evaporation, absorption

wavy edge

paper edge grows wavy with increased moisture

laminated/coated paperboard

paperboard coated/laminated with plastic film

solid unbleached sulfate (SUS)

paperboard used where either very high strength (puncture, tear, etc) or high wet strength properties are required e.g. beverage carriers, cereals, shoes, toys, etc.

property of offset ink

pasty

property of screen ink

pasty

flute direction

perpendicular to machine direction; affects structural strength (like fiber direction in paper)

adhesive strength

pick-up strength

colorant types

pigments disperse dyes dissolve

The print on T-shirt cracks after few laundry cycles. What could be added to the ink formulation to avoid this?

plasticizer

UV curing drying mechanism

polymerization (monomers dry when exposed to UV light)

True or false: Thixotropic means the viscosity change of inks are dependent on time

true

True or false: bleach test tests the color strength of inks

true

True or false: ink adhesion is about how well the dry ink film can adhere to the non-absorbent substrates

true

True or false: ink length only relates to paste inks

true

True or false: offset is oil based and long ink

true

True or false: vehicles carry and disperse ink pigments; consists of ink oils, binders, and solvents

true

absorbency of coated vs. uncoated

uncoated has higher absorbency because coated has greater ink hold-out (ink stays on surface)

black pigments

used more than other pigments, more permanent (e.g. furnace black, carbon black)

VOC

volatile organic compound

dimensional stability of corrugated board

when high relative humidity (humid) drops to low (dry), a tight edge forms moisture curl is perpendicular to machine direction