Hot melt pressure sensitive adhesive is a kind of pressure sensitive adhesive. It is mainly made of rubber, resin and rubber oil mixed and heated to melt state and then coated on cotton paper, non-woven fabric or plastic film.
Low cost is its greatest advantage, but the disadvantage is that the viscosity is obviously affected by temperature. Mainly used for sealing boxes, sealing boxes, paper packaging, beverage bottle labels, sealing aluminum foil, flexible packaging and other packaging and environmental protection paper stack board, etc., to adapt to all kinds of materials.
Medical hot melt pressure sensitive adhesives are a kind of medical hot melt adhesives, which are widely used in the manufacture of medical and health products such as medical adhesive cloth, transfusion patch, wound patch and so on. Medical hot melt pressure sensitive adhesives have both hot melting property and pressure sensitivity. In the process of making rubber products, they should be heated and melted by special equipment, which reflects the hot melting property. The adhesive products such as medical adhesive cloth and wound patches can be bonded by finger pressure after tearing, which reflects the pressure sensitivity.
Requirements and Standards for Medical Hot Melt Pressure Sensitive Adhesives
When medical hot melt pressure sensitive adhesive is applied to medical products such as medical tape, elastic bandage, wound sticker and surgical incision film, various problems arising from contact with skin must be considered.
Medical hot melt pressure sensitive adhesives in use require no irritation to the skin, such as redness, itching, small papules and other allergic reactions.
Hot melt pressure sensitive adhesive products have good air permeability, which can greatly reduce skin allergy and make the skin breathe normally after covered by adhesive products. It has a positive effect on skin perspiration, keeping the wound dry and accelerating wound healing.
Human skin is different in dryness and oiliness, as well as in dense and non-hairy hair. There are also smooth and rough points. Medical hot-melt pressure-sensitive adhesive products can meet the needs of most people's skin and stick to the skin. They can still maintain a certain adhesive force in the humid or sultry environment, under the condition of skin perspiration and body fluid secretion, and do not produce the phenomenon of warping up and falling off quickly. 。
4. Skin compatibility peeling strength should not be too high
The peeling strength of medical hot-melt pressure-sensitive adhesives adhering to skin should not be too high and should be kept within a certain limit. Otherwise, the skin will feel uncomfortable and tense. When uncovered, the skin will feel pain and easily pull up the sweat and hair, which will damage the skin.
Good initial adhesion to skin
Because most of the materials are used on or around the wound, it is not suitable to press hard, so the initial adhesion of the rubber products is good, and it can adhere to the skin in an instant.
No residual glue after tearing
There is no residual glue left after tearing from the skin, especially around the edge of the adhesive material.
5. Suitable disinfection treatment
Many stickers and wound stickers used in wounds need to be disinfected. They can not deteriorate because of disinfectants. At present, gamma-ray and drill-ray disinfection have little effect on the adhesive, while hot steam disinfection may cause changes.
6. Medical experiments must be carried out.
(1) Cytotoxicity test: Check for possible toxic substances in adhesives.
(2) Skin irritation test: Used to test the possibility of skin irritation caused by precipitates in the glued material.
(3) Skin allergy test: Repeated trials were conducted to test skin allergy response in different age groups and different people.
There are many ways of gluing hot melt adhesives. No matter which way of gluing, hot melt adhesives must be pre-heated into a melting state in the melt trough, and then directly sprayed or transferred to the substrate or stickies by appropriate gluing equipment. Coating on-line learned that the common medical tape substrates are non-woven fabric, PE film and silk fabric. There are two types of gluing equipment: rollers and die heads.
The application of hot melt pressure sensitive adhesives in medical tape market requires not only proper coating operation and thermal stability, but also non-itching, clothing and breathability.
As mentioned in the previous section, hot melt pressure sensitive adhesives can be coated on various special substrates with special dies or rollers. However, the hot melt pressure sensitive adhesives for medical tapes usually have high fluidity, which is easy to penetrate into porous substrates and cause glue overflow.
In addition, many medical tape substrates can not withstand high heat and may be extended, deformed or even destroyed when glued. Owing to the above troubles, the operators usually apply the hot-melt pressure-sensitive adhesive on the high-heat resistant release paper first, and then transfer the hot-melt pressure-sensitive adhesive to various substrates.
2 no itching.
Solvent glue commonly used in medical tapes can cause skin allergies and zinc oxide powder should be added to the glue. The function of zinc oxide powder has two aspects: one is to reduce the allergy of solvent glue to skin; the other is to improve the hygroscopicity or sweat absorption ability of glue.
Because the natural tackifying resins such as rosin or esterified rosin are not suitable for medical tapes, the soft and wettability of the hot melt pressure sensitive adhesive itself must be used to obtain the skin adhesion, i.e. the so-called viscoelasticity. When designing the hot melt pressure sensitive adhesive for medical tapes, special emphasis should be placed on the fluidity of human skin. After the tape is attached to the skin, it must have the ability to continuously wet and close to the skin surface. Ideally, the tape should not fall off because of the bending motion of the joint.
In order to prevent skin irritation, the composition of hot melt pressure sensitive adhesive for medical tape usually does not contain polar substances (hydrophobic polymers). Because it can't absorb moisture and sweat. If proper air permeability is to be obtained, the tape base material and glue can be drilled at appropriate intervals behind the adhesive. Or use special coating processing equipment to create a non-full plate, coating the surface.