Surprisingly, the history of stickiness did not begin with tapes. It is actually credited to the bees or the woodworkers in ancient Egypt who used glue created from natural, viscous substances such as resin and beeswax to hold materials together.
Before adhesive tapes, epoxies and glues did most of the sticky job in modern times. However, they have drawbacks, particularly in household use. The messiness, its permanence, and drying to a hard finish made conventional glues less-than-ideal. Then comes 1925, the year when adhesive tapes were invented.
Adhesive tapes are a mix of a special component and an adhesive film used to bond or join objects together instead of applying screws, fasteners, or welding. Using adhesive tapes in lin place of mechanical fasteners enables you to use lower temperature applications, simplifying the manufacturing processes.
Moreover, adhesive tapes can protect your surface area because you do not have to damage the surface just to put screws or fasteners. Furthermore, adhesive tapes are excellent solutions for automated product production, while liquid adhesives are kind of sloppy and time-consuming to use since they have to be rolled or sprayed onto the surface before bonding can occur.
Common Adhesive Tape Materials
There are different classes of adhesive tapes, such as water activated tape, heat activated tape, and pressure sensitive adhesives (PSA). The PSTC or Pressure Sensitive Tape Council denotes PSAs as a continuous flexible strip of paper, cloth, metal, or plastic coated on one or both sides with a permanently tacky adhesive at room temperature which adheres to various surfaces. It only requires light finger pressure with no change of phase on a roll form.
What differentiates a PSA tape from other kinds of adhesives is that activation by any solvent, water, or even heat is no longer needed just to exert a strong adhesive force towards diverse materials like paper, plastic, glass, wood, or even metal. Although the adhesive used on PSA tapes might seem likely as they all adhere well, are tacky, and resist stress, it turns out they are pretty different. There are advantages and disadvantages for each class of tape, whether it is rubber, acrylic, or silicone-based adhesives.
Rubber is the oldest kind of adhesive made from natural rubber, but it needs a resin in order to make it into an adhesive. Rubber adhesive systems are usually used for indoor applications with low stress requirements, including masking tapes, duct tapes, carton sealing tapes, and lament tapes.
They generally adhere well to low surface energy substrates and are formulated for excellent removability. Moreover, they are not tacky by nature. Therefore, it is needed to add tackier resins to produce them. Here are the two main categories of rubber adhesives:
- Natural Rubber
These natural rubber adhesives typically have a high molecular weight with long polymer chains. They usually adhere to low surface energy (LSE) substrates and portray clean removability and good shear. Apart from being often less expensive, natural rubbers have an initial high tack, unlike acrylic, which needs time to cure. However, they are poor when it comes to temperature resistance and aging properties.
- Synthetic Rubber
Synthetic rubber is commonly known as “hot melt” adhesive. This adhesive tape material is thermoplastic with a short polymer chain or low molecular weight. It is more customizable compared to natural rubber adhesives for better LSE adhesion with more tack and some temperature or UV aging resistance. Since it offers higher adhesion and shear resistance, synthetic rubber is perfect for sealing cartons and packages.
Interestingly, the weak features of rubber adhesives are bested by colorless acrylic adhesives. This is because acrylics are stable to oxidation and exposure to UV light, and their stability in oxidation provides years of protection against UV light.
Acrylic adhesive systems are used for indoor and outdoor applications that need more permanent long-term bonding solutions. Acrylics are naturally tacky, and the tackier feature is beneficial to boost their quick-stick properties. However, acrylic adhesives cost about twice as much as rubber adhesives. Also, they are not quite as good as natural rubber when it comes to harder-to-adhere surfaces, plus they require a significant period to cure. Here are the two main types of acrylic adhesives:
- Solvent Acrylic
Solvent acrylic adhesives got their name because their polymer grains dissolve in a solvent. Generally, these PSAs do not adhere well to LSE substrates, but they showcase better property retention than rubber under several circumstances.
- Emulsion Acrylic
These water-based PSAs contain spherical particles surrounded by a surfactant in a water carrier. Emulsion acrylics are generally less expensive and more eco-friendly than solvent acrylics. Still, they do not provide good moisture resistance because of their water-based properties, which leads to solvent acrylics being preferred for critical applications.
Silicone adhesives offer many years of service life, but they are considered the most expensive kind of adhesive. They possess a very high temperature resistance and can handle harsh environmental conditions. Despite silicone adhesives’ bonding strength, they are often incorrectly perceived as having deficient sticking capability due to their low initial bond strength.
Tapes with silicone adhesive solutions are generally utilized for critical applications where adhesives are exposed to extreme temperatures or environments. This includes the electrical industry, where the temperature is a difficult feat. Moreover, they cost twice as much as acrylics, but similarly to the latter, they can also be used against the skin, making them widely used for medical applications.
Adhesive Tape Making Machine Introduction
Adhesive tape was invented in 1925 as a painter’s masking tape for auto body shops that led to transparent tape designed to seal the cellophane wrap used by the food industry. Then the adhesive tape was introduced as a household item, and the idea just stuck.
The science of the adhesive tape manufacturing process starts with polymerization. This means the structure of adhesives and the polymers or molecule chains are combined in the chemical process. In the aftermath, the adhesives are prepared to be applied quickly and very thinly to the preferred backing material. But how this takes place entirely depends on the adhesive.
In the process of adhesive tape making, the adhesive mass, backside treatment agent, primer, and other important components are either in-house manufactured or purchased. Then a tape base element is coated using these materials with a solvent being removed by drying and then wound around in the form of a roll. The coated roll is further cut to the desired width and then packed.
In addition, the transfer of the PRTR (Pollutant Release and Transfer Register) chemicals other than the solvents (both liquid and solid) used for the base material, adhesive mass, primer, backside treatment agent, and so on also took place from the production process such as coating, rewinding, and slitting of tape rolls.
Adhesive Tape Manufacturing Process
Here is a general step-by-step process of adhesive tape making:
1. Polypropylene Film in Unwinder
Whether the production floor is making shipping tape, electrical tape, and so on, the adhesive tape manufacturing process starts with the rolls of a plastic film called polypropylene.
The rolls go on a machine called the unwinder. Workers then position a strip of adhesive splicing tape along the end of each row to enable them to connect one roll after another creating an uninterrupted feed to the production line.
2. Unwinding Rolls onto Splicing Tape
Once the roll unwinds completely, its end sticks onto the splicing tape at the beginning of the next row. When that rolls unwound, its end will stick to the beginning of the next, and so on.
3. Automatic Tension Adjuster
An automatic tension adjuster makes sure that the machine pulls the film evenly to prevent it from ripping.
4. Application of Solvent
The unwinder also applies a solvent to the film surface. This prevents the film from sticking while unrolling. In order to transform this film into a tape, the machine coat one side with a hot adhesive known as hot melt made from several ingredients.
The synthetic rubber gives it flexibility, a UV protector keeps it from drying and discoloring, while an antioxidant prevents aging. The addition of synthetic resin makes it sticky while putting pigmentation oil provides a choice of color, like a tan for packing tapes.
5. Preheated Holding Tank
Next is loading the hot melt into a preheated holding tank which keeps them out at a piping 390 degrees Fahrenheit to prevent the tape from hardening. The tank pumps adhesive to a machine called the blower. Then wipe away the excess and roll the film.
6. Use of Cooling Roller
A cooling roller that black went on top immediately hardens it. A computerized sensor ensures there is an even coat of adhesive. Otherwise, it automatically signals the pump to adjust the output if there is not. If the adhesive tape is double-sided, a separating layer is also inserted when winding. Afterward, the process begins again to coat the other side of the adhesive tape.
7. Rewinder Machine
On a rewinder machine, it rolls the tape into spools. Remember the unwinder that spliced the rolls together? The rewinder machine unsliced them. When all are filled, a knife separates the adhesive tape at the splice point so that winding can begin on the next phase.
8. Slitter Machine
The tape on just one of the manufactured spools would run an average length of 85 football fields. The spool speed a row of sharp razor blades called the slitters, which divide can divide the five-foot-wide tape into several strips. A shipping tape, for instance, is almost 2 inches wide, so you can get 31 strips per spool.
9. Finished Tape Rolls
Each strip winds on a tilled cardboard core, and its end is sealed with the tab. The length of tape per roll varies according to the customer’s specifications. As the machine ejects the finished tape rolls in the next batch of cardboard courses, it is off to the packaging department.
10. Quality Control Check
Before packing and shipping, manufacturers make sure that their adhesive tapes pass through a quality control check as they test the sample roll from each spool.
For instance, in one test, they unroll the tape’s sticky side up them release a tiny stainless steel ball down an incline, measuring how far the ball rolls before it sticks and comes to a stop. The ball has to adhere within a certain distance to pass the test. The stopping distance varies depending on the type of adhesive tape.
Other Materials Used for the Backing of Adhesive Tapes
Adhesive tapes and films differ when it comes to the carrier or backing material used. Here is a list of the most common carriers.
Paper tape items have a paper backing. They are also known as flatback tape.
A cloth carrier often incorporates a woven cloth material or a fabric layer for reinforcement, extra strength, and heat resistance features.
Felt or non-woven adhesive tapes are usually applied to substrates to avoid scratching.
Foam backing tape possesses an adhesive protected by a liner. Foam is often used for sealing, mounting, and weather-stripping.
- Metal Foil
Aluminum, aluminum-reinforced, and lead backings resist high humidity, extreme temperatures, and flames. Metal adhesive tapes are typically designed for taping joints and seams against vapor or moisture. Copper foil backing is used when producing multilayer PCB (printed circuit boards). On the other hand, aluminum foil is laminated to plastic or paper films to provide more strength.
- Plastic Film/Polymer
Thermoplastics and thermosets are the two general categories of plastics. Plastic products contain one or more plastic layers, and they can be clear, colored, printed, or plain. Also, plastics can be single-layered or multi-layered and mixed with materials such as paper and aluminum.
- Polyethylene terephthalate (PET)
PET products use a PET or polyester backing in the form of a film or laminate, which is also known as mylar.
Polyimide adhesive tape contains a polyimide film and a heat-resistant silicone adhesive. They are useful substrates for the manufacture of flexible circuit materials.
- Polyvinyl chloride (PVC)
PVC or vinyl products use a vinyl or PVC backing to resist wear, tear, weathering, and abrasion.
Fiberglass material or a glass layer offers exceptional stability in harsh surroundings by resisting shrinking, burning, rotting.
Commonly known as strapping tape, filament tape is composed of thousands of filaments woven into yarns that are embedded into the adhesive. It is a solid and versatile material that allows the user to bundle similar or odd-shaped objects for shipping or storage.
Adhesive tapes are very beneficial to many industries, including the medical sector, electrical industry, food and beverage, aircraft, and especially the shipping commerce. We hope that this article has been helpful. If you wish to find a reliable adhesive tape manufacturer to support your business, check out our Shosky for affordable and high-quality adhesive tapes.