Unit 2 - Labels Flashcards
Name the 3 major types of label
- Pre-glued
- Glue applied
- Without glue
Name the 3 types of pre-glued labels
- Gummed
- Linerless
- Pressure sensitive
Name the 2 types of glue applied labels
- Hot melt wrap-around
- Cold glue (patch)
Name the 2 types of without glue labels
- In-mould
- Sleeve
Name 3 things which affect label design
- EAN/GS1 bar code is required somewhere - must be a specific size to give readability
- Often need a label identification code
- Legislation states that test such as ingredients and weight must be included
What shaped labels are guillotined?
Used for square or rectangular labels
How are guillotined labels made?
Stack of up to 1000 printed labels are presented to a guillotine machine and a knife blade slices downwards at an angle to cut through the stack
What shaped label are die cut?
Any label which is shaped or has rounded corners
Give an advantage of die cut labels
Range of shapes available
Give 2 disadvantages of die cut labels
- Separate die needed for each shape
- More waste than guillotined - the trim have to be removed and recycled
How are ungummed wet glue labels applied?
- Can either be placed or wrapround (e.g. a tin can)
- Glue is applied to the label and applied to the pack firmly
- Up to 100k containers per hour
How are plastic labels fed into a machine and why?
Almost always reel fed - this is due to issues handling a thing plastic label in a sheet form due to static
Give 4 advantages of plastic labels
- They are very flexible and give less wrinkling for distortion than paper due to moisture absorbance - you also get no mould growth on moist labels
- Better scuff resistance than paper labels due to the reverse printing
- Increase resistance to tearing and are preferred for corrosive products
- More easily removed in-tact for recycling
What 3 things affect paper choice for labels?
- Porosity
- Stiffness
- Curl
Why must paper porosity be taken into account when making labels?
Important to consider if a vacuum is used at any stage during handling
Why must paper stiffness be taken into account when making labels?
- Affect the ability to wrap around
- Different diameter containers may require adhesives with different tack levels to ensure the label doesn’t peel away before the adhesive has set
Why must paper curl be taken into account when making labels?
Paper will curl if the RH during manufacture is different to the RH during processing
More moisture is absorbed on the unprinted or uncoated side resulting in curl
How should paper labels be stored?
Labels should be stored between 18-22°C and 60-70% RH
How does fibre orientation affect label application for paper labels?
Fibre direction in labels is always specified as being parallel to the base of the label - this is because the label will curl vertically and therefore give less chance of falling off a container
Name the 4 types of adhesive used for ungummed wet glue labels
- Starch-based
- Emulsions
- Hot melt - good for rough surfaces
- Casein - good for bottles that may be chilled in ice water
Name 3 disadvantages of PSL labels
- Expensive
- Coated backing paper must be thrown away
- Not easily recoverable due to release coating on one surface
Give 2 advantages of PSL labels
- Cleaner to apply as you do not need adhesive stations
- Faster changover times
How are PSL labels fed into the machine
Reel fed
How are PSL labels constructed
Labels are cut from the web using a rotary die, a flat die, or laser die cutting - designed to cut through the paper but not the backing paper
What 4 things affect adhesive choice for PSL labels
- Substrate
- Storage
- End-use of product
- If it is peelable or pemanent
Describe how PSL labels should be stored
- Must be stored at the correct temperature and used within 6 months otherwise the adhesive can bleed around the die cut edge leading to problems with unwinding
- Should be stored horizontally to prevent reel distortion
Name 4 things that affect material choice for PSL labels
- Performance needed during appplication
- Storage
- Economics
- Environmental effects
Describe in-mould labels
An alternative to printing containers directly - offers high quality gravure printing over a large area
Label is inserted into the mould at the start of the moulding process
How would a plastic in-mould label work?
If the label is plastic, the process will fuse it with the container
How would a paper in-mould label work?
If paper, it will need to be pre-coated with a heat sensitive adhesive to work
Give 5 advantages of in-mould labels
- Applied during manufacture rather than needing another process
- Ability to have all-round decoration
- Excellent adhesion to the component
- Good for large components
- Reverse printing means label is also resistant to scuffing
Give 2 disadvantages of in-mould labels
- Cost is higher
- Less flexibility during limited edition promotions (however, you can place a label over this)
Give 5 advantages of shrink sleeve labels
- Allows for complete graphic coverage of the container
- Good scuff resistance
- Ability to label complex shapes
- Can offer tamper resistance if in the right palce
- Can be used to combine packs
What are shrink sleeve labels usually made from?
PS, PVS, PETG, or OPP
What techniques are used to print shrink sleeve labels?
Flexo or gravure
Give a disadvantage of shrink sleeve labels
Graphic design needs to be distortion printed to produce the final image - this can be problematic in bar codes etc. so these need to be placed in an area of minimum shrink
How are shrink sleeve labels supplied to the machine?
Supplied as reels, but knives cut off one label from the reel using location marks; the sleeve is then dropped over the container and passed through a shrink tunnel
In what directions do shrink sleeve labels shrink?
Designed to shrink in a radial direction but not vertically
Describe how stretch sleeve labels work
Ready-to-use labels which are stretch and applied without adhesives - their natural elasticity keeps them in place
Give 5 advantages of stretch sleeves
- Easy to apply as no heat tunnel is required
- Allows for 360° graphics
- Can be used for multipacks
- Lower cost than shrink sleeve as you do not need a heat tunnel
- Easily removed for recycling
Give a disadvantage of stretch sleeves
Cannot be used for detailed shapes
What material cannot be used to make stretch sleeves?
Paper
Describe how roll on / shrink on labels are applied
- Applying a shrinkable, reel-fed label onto a container
- Hot melt adhesive is applied to fix the label to the container - then passed through a heat tunnel to shrink it onto the container
What materials are roll on / shrink on labels made from?
PP, PS, PVC, or PE
Describe tag and neck collars and give a disadvantage of them
- Usually used for promotions to provide extra information
- Is an extra operation on the packing line
Describe booklet labels
- Provide extensive extra information in the form of a booklet
- Held closed with peelable self-adhesive
Name 8 testing requirements for labels
- Print adhesion
- Rub resistance
- Surface slikp
- Curl (for paper)
- Low chlorine if used for cans to reduce corrosion and label staining
- Colour fastness
- Gloss levels
- Colour standards
