Pressure-sensitive adhesive research results

5 blends/copolymers

The blending or copolymerization allows the pressure-sensitive adhesive to have the advantages of two or more polymers at the same time, further improving its performance. Interpenetrating network (IPN) technology is a recently developed effective way to improve the compatibility of blend systems. Zhou Ming and others used Polyurethane/Polyacrylate (PU/PAA) IPN technology to modify the polyacrylate pressure sensitive adhesive. Because the polyurethane network provides good heat resistance, the polyacrylic acid network provides good initial tack, making The obtained pressure-sensitive adhesive has a heat resistance of 125 degrees, and the mechanism of its heat resistance is discussed. A new type of functional monomer and acrylate copolymer were used to modify and prepare the base resin, and IPN technology was used to blend and cross-link the modified rosin and butanone oxime-terminated polyisocyanate compounds to develop a single-component cross-linkable compound. Acrylic pressure-sensitive adhesive.

With the double-sided pressure-sensitive adhesive tape made of the adhesive, the main performance indicators are greatly improved than domestic ordinary double-sided pressure-sensitive adhesive tapes, and have reached the level of similar foreign products. Can be widely used in automotive, home appliances and other parts of the strong adhesive bonding.

When the acrylate monomer in which rosin or hydrogenated rosin is dissolved is subjected to emulsion copolymerization in one step, the conversion rate of the monomer is significantly reduced due to the free radical chain transfer effect of the tackifying resin molecule. The seed emulsion is prepared by emulsion copolymerization of most of the acrylate monomers, and the remaining acrylate monomer with the tackifying resin dissolved therein is added to the seed emulsion to carry out the second emulsion copolymerization, which can significantly increase the total conversion of the monomers. rate. The performance of the obtained tackifier resin-acrylate composite emulsion copolymer pressure-sensitive adhesive is greatly improved over the one-step method. The effect of C5 petroleum resin and rosin as tackifying resin on the performance of the polyacrylate pressure sensitive adhesive was studied. The results showed that with the increase of the content of rosin resin, the 180 degree peel strength increased, the fast tack force remained unchanged, and the holding tack force decreased. With the increase of petroleum resin content, 180-degree peel strength, fast-adhesion force, and tack-holding power have all dropped significantly. Solution copolymerization with a mixture of acrylates also yielded satisfactory adhesives.

Copolymerization/blending is also an effective method for obtaining high peel strength pressure sensitive adhesives. The influence of the amount of acrylic ester (AE), vinyl acetate (VAc), acrylic acid (AA), epoxy resin and rosin modified resin on the performance of the pressure-sensitive adhesive was studied in the grafted modified natural latex system. An optimum ratio was obtained and a pressure-sensitive adhesive with a peel force of 1500 N/m was obtained by heat treatment of the sample strip. Another typical example is the copolymerization of polyacrylic acid monomers, and the synthesis of a high peel strength by reducing the emulsifier concentration, adding an appropriate amount of acrylic acid, and using a self-crosslinking agent such as methacrylamide. Sensitive glue, its maximum 180 degree peel force up to 2210N/m.

6 Suspension polymerization platform

Acrylates are used as the main monomer, and microsphere-shaped pressure-sensitive adhesives with a certain size range can be prepared by suspension polymerization. Compared with solvent-based and emulsion-type pressure-sensitive adhesives, they have more unique properties: 1 Repeatability, that is, coating on the surface of substrates (such as paper, fabrics, plastics, metals, etc.) to make products (such as Post- Itnote, protective film, etc.) has re-peelability and reusability; 2 good resistance to adhesive layer transfer; 7 can be applied with light pressure to achieve practical adhesive strength, and even after heavy pressure is applied, the strength will not be excessive. Increase. Such pressure sensitive adhesives were developed in the late 1980s.

In recent years, domestic research has begun and there are such products (Post-itnote) available. For example, Li Guoqiang et al. and Murray et al. used isooctyl acrylate/methyl acrylate/acrylic acid as monomers to perform micro-spherical pressure-sensitive adhesives that have been subjected to peroxide polymerization to obtain a microsphere-shaped pressure-sensitive adhesive that has reached the level of similar foreign products. Mass production.

7 Hot melt table type

Hot Melt Pressure Sensitive Adhesive (HMPSA) has both hot melt and pressure sensitive properties. It can be applied in the molten state, and can be quickly bonded by applying light pressure after cooling and hardening. Hot-melt pressure-sensitive adhesives do not contain organic solvents and do not pollute the environment. They are simple to manufacture, easy to use, and versatile. Due to pressure from environmental protection and performance defects in aqueous solution systems, the importance of hot melt adhesives is increasing, and it is expected to gradually replace solvent-based pressure-sensitive adhesives.

The styrenic thermoplastic elastomer is a styrene-diene-styrene block copolymer, abbreviated as SDS, in which the diene is butadiene, the copolymer is SBS, and if it is isoprene, it is SIS. Since the SDS structure contains two segments of plastic and rubber, the properties of the two, that is, the mechanical properties of the rubber and the technical properties of the plastic, are very suitable for the preparation of hot melt pressure sensitive adhesives. In 1965, Shell Chemical Company of the United States commercialized SBS and SIS, and began to manufacture hot-melt pressure-sensitive adhesives. SIS is also the material of choice for hot-melt pressure-sensitive adhesives.

The research and production of hot-melt pressure-sensitive adhesives in our country started late, and the annual output in 1995 was only 3 000 tons, which is mainly used for the production of sanitary napkins and diapers. At present, there is a certain degree of development, and the application field is constantly expanding. SDS hot melt pressure sensitive adhesives can be used to make general pressure sensitive adhesive products. It can also be used to produce cleaning tools, children's toys, and crafts. Products, PVC floor tiles, etc., can also be used for car seat cushions, backrests, carpets and other parts of the bonding. A force of Urumqi, Xinjiang Uygur Autonomous Region applied SDS-type hot-melt pressure-sensitive adhesives to repair butyl rubber chemical protective clothing. The results are very good. It solved many years of unresolved problems and passed the technical appraisal of the General Logistics Department. The SDS-type hot melt pressure-sensitive adhesive with excellent comprehensive properties was successfully developed using a mixture of SIS and SBS. Several properties of SBS thermoplastic elastomers were improved by adding tackifiers, plasticizers, and other fillers, resulting in a shear strength of 36 N/cm2, a 180 degree peel force of 1,164 N/m, and a greater tack force. 12h hot melt pressure sensitive adhesive.

8 Crosslinked/cured type

Cross-linked/curable pressure-sensitive adhesives are a kind of initial tackiness of pressure-sensitive adhesives at the initial stage of adhesive bonding, and serve as a temporary positioning and bonding function. After bonding, under appropriate conditions such as light, heat, pressure, humidity, and radiation Crosslinked curing, etc., so that the adhesive strength and heat creep resistance can be improved adhesive. Many kinds of pressure-sensitive adhesives have been developed abroad, but due to the limitations of their technologies and varieties, there are few domestic studies.

Due to the high cohesion and high temperature resistance characteristics of such pressure-sensitive adhesives, they have received more attention in recent years. Zhou Ming et al. used UP/PAA interpenetrating network-based pressure-sensitive adhesives to allow an excessive amount of NC0 reactive groups and then cured under moisture or heating conditions to obtain a curing-type pressure-sensitive adhesive. The adhesive not only has a good initial performance, but also has a significantly improved performance after curing, and can maintain a high operating temperature. The short-term use temperature can even reach 150-250 degrees.

In addition, Xu Wei et al [23] also used NR and SBS as the main raw materials, using the early shallow cross-linking curing technology route to prepare a heat-curing special pressure sensitive adhesive for electronic capacitors. The pressure-sensitive adhesive obtained has excellent properties, particularly heat resistance, melting temperature of up to 170° C., and retention of the capacitor stuck on the tape at a temperature of 125° C. for 4.5 h or 170° C. to UO° C. for a short period of time without leaving any residue on the leads. Glue, and low cost, can be comparable to imported pressure sensitive adhesives of the same type.

In addition, biosynthetic and hydrosol-based pressure-sensitive adhesives have rapidly developed in foreign countries and are still at an exploratory stage in China. Therefore, reports in this area are still rare and will not be introduced here.

In recent years, with the rapid development of China's economy, the demand for pressure-sensitive adhesives and related products in the packaging and related industries is increasing, and the development of pressure-sensitive adhesives is changing with each passing day. The emergence of new synthesis methods and cross-link curing methods offers the possibility of synthesizing high-performance pressure-sensitive adhesives that meet both environmental and safety requirements. It can be expected that the research on pressure sensitive adhesives and their products will receive more extensive attention, and further adopt the latest achievements in other fields to make them develop in the direction of functionalization and diversification, gradually changing the long-term single species in this field in China. Many specialty glues rely on imports.