1, thermoplastic elastomer HMPSA
The appearance of styrenic block copolymers, as a main raw material of HMPSA, has promoted the development of HMPSA. However, due to the structure of the SIS, the properties of the formulated HMPSA, such as thermal oxidation resistance and low-temperature adhesiveness, need to be improved, which limits the expanded use of HMPSA. Therefore, an important task of this kind of HMPSA is to synthesize new block copolymers and tackifying resins, and to develop a pressure-sensitive adhesive with excellent properties through formulation and combination.
2. Novel block copolymers
At present, the main application of SIS, has also begun to apply SEBS, SEPS, HSBR and other elastomers. Recently, a star SIS was synthesized using a polyfunctional coupling agent. Compared with the linear SIS having the same styrene hard segment content and molecular weight, the melt viscosity was low, and the coupling point substantially acted as a cross-linking point, so the cohesive force was high. The formulated HMPSA has a high tackiness and fast tack, while the glue has a low viscosity. A new type of copolymerized SEBIS, whose backbone is SEBS (about 2/3), about 1/3 of isoprene polymer blocks are connected, with the light and oxygen stability of SEBS, and the adhesion of SIS. The formulated adhesives have low viscosity, high shear properties, excellent adhesion, and have an adhesiveness that SEBS and SIS cannot achieve without physical compounding. Hydrogenated butadiene-isoprene-butadiene block copolymer HMPSA, 11O °C melt viscosity of 5.3 Pa · s, has a good process stability, viscosity, low temperature, creep resistance.
Kratonliquid polymer [Figure 2 (not shown)] is a highly viscous liquid reactive polymer at room temperature. It can be melted at medium temperature and can be coated with a heat-resistance film. The heat resistance is improved by chemical crosslinking, and the main chain structure is not. Polar, sticky PP is good. Asahi Kasei developed SBBS Polystyrene (poly-1,4-butadiene-butene)-polystyrene, which has good thermal stability, soft segment Tg is 10 °C lower than SEBS, and excellent processing fluidity.
3, C5/C9 copolymer resin
Tackifying resins are an important component of HMPSA, and now also use a certain copolymerization ratio of C5/C9 petroleum resins, which can improve the compatibility with SIS, reduce the viscosity of pressure-sensitive adhesives, improve fast adhesion and low-temperature release properties.
4, acrylic HMPSA
Around 1980, the technology of pressure-sensitive adhesive made of acrylic hot melt adhesive attracted attention. With the development of acrylic copolymers, block copolymers and macromonomers, and the progress of cross-linking technology, Acrylic HMPSA has developed accordingly. , Overcoming some of the shortcomings of elastomer HMPSA in the past, such as thermal stability, seepage back, transparency and so on. Ren Jiaxiang et al studied the type and amount of butyl acrylate and 2-ethylhexyl acrylate, MMA or methyl acrylate, VAC, functional monomers (acrylic acid, maleic anhydride, acrylamide, etc.) for acrylic hot melt pressure sensitive adhesives. The impact of performance. The HMPSA can be prepared from an acrylate polymer containing OH or COOH, a blocked isocyanate and a quaternary ammonium salt, which can be melt-coated at 100-110°C and heated at 120-140°C after bonding. The macromonomer was prepared by the reaction of 2-hydroxyethyl methacrylate, phthalic anhydride and phenyl glycidyl ether, and then polymerized with 2-ethylhexyl acrylate to prepare HMPSA with good initial viscosity. Commodity ラクリメルト NO. 4580 is a acrylate copolymer, light yellow transparent, softening point 78 °C, can be 140% coating, direct coating of polyethylene. DuPont has developed phase-separated acrylic block copolymers that disperse acrylic hard blocks in an acrylic elastomer matrix. The two are thermodynamically immiscible. This structure has a thermally reversible physical cross-linking mechanism, heat-melt coating, and cooling. After curing, the block copolymer physically crosslinks. The copolymer is made of hydrogenated petroleum resin and hydrogenated rosin ester to make HMP-SA. It has good adhesion to various substrates (metals, plastics, polypropylenes), good thermal oxygen stability, and stable viscosity when melted.
Acrylic HMPSA will continue to be developed in the future. Through the synthesis of the main polymer, secondary processing and other means, it will develop a product with the same performance as the solvent-based acrylic pressure-sensitive adhesive.
5, UV/EB curing HMPSA
There are three problems with general UV/EB cured pressure-sensitive adhesives: 1 price: 2 on skin irritation and odor problems; 3 initial investment. However, the pressure-sensitive product market has recently turned to low VOC, high productivity, and high performance, opening new development opportunities for UV/EB-cured HMPSAs. Butyl acrylate-methyl acrylate-ethoxyethyl ethoxy diethylene glycol diacrylate copolymer (Tg-35 °C,
Mw125000) Add benzophenone to make HMPSA, coated on polyester film, after photocuring, the adhesive force is 12 N/25 mm, and the saturated polyester with end-acrylic group holding ≥1440 min is melt-coated at <100 °C , EB or UV irradiation, pressure-sensitive adhesive cross-linking reaction. PSA-705 (Kyoeisha Chemical) is an acrylic polyurethane HMPSA with a polyester skeleton, viscosity 70 Pa·s (120°C), Mw31000, low odor, low volatility, low toxicity, thermal stability, high-speed hardening, etc. . The Acrymelt UV industry began selling in 1998. The main component is an acrylate copolymer, a photoinitiator containing radical polymerization, and a 300-nm high-pressure mercury lamp that cures the pressure-sensitive adhesive. BASF uses benzophenone-based acrylic monomer copolymers Acronal DS3429, 3458 series, residual monomer <0.4%, developed a monomer-free HMPSA, to solve the problem of thermal stability. Shell developed the SIS cross-linked dedicated Siskronat-1320x. This star-shaped SIS is sensitive to EB radiation, and it does not lose its pressure-sensitive viscosity, temperature resistance, and solvent resistance after cross-linking.
In recent years, the cost of light-curing technology has been declining. Through comprehensive evaluation of the entire production process, UV-curable acrylic HM is superior to solvent-based acrylic glue; the total equipment investment cost of solvent-based, hot-melt, EB-HM, and production costs are compared. , EB/UV-curable HMPSA can be considered as an economically attractive technology
The appearance of styrenic block copolymers, as a main raw material of HMPSA, has promoted the development of HMPSA. However, due to the structure of the SIS, the properties of the formulated HMPSA, such as thermal oxidation resistance and low-temperature adhesiveness, need to be improved, which limits the expanded use of HMPSA. Therefore, an important task of this kind of HMPSA is to synthesize new block copolymers and tackifying resins, and to develop a pressure-sensitive adhesive with excellent properties through formulation and combination.
2. Novel block copolymers
At present, the main application of SIS, has also begun to apply SEBS, SEPS, HSBR and other elastomers. Recently, a star SIS was synthesized using a polyfunctional coupling agent. Compared with the linear SIS having the same styrene hard segment content and molecular weight, the melt viscosity was low, and the coupling point substantially acted as a cross-linking point, so the cohesive force was high. The formulated HMPSA has a high tackiness and fast tack, while the glue has a low viscosity. A new type of copolymerized SEBIS, whose backbone is SEBS (about 2/3), about 1/3 of isoprene polymer blocks are connected, with the light and oxygen stability of SEBS, and the adhesion of SIS. The formulated adhesives have low viscosity, high shear properties, excellent adhesion, and have an adhesiveness that SEBS and SIS cannot achieve without physical compounding. Hydrogenated butadiene-isoprene-butadiene block copolymer HMPSA, 11O °C melt viscosity of 5.3 Pa · s, has a good process stability, viscosity, low temperature, creep resistance.
Kratonliquid polymer [Figure 2 (not shown)] is a highly viscous liquid reactive polymer at room temperature. It can be melted at medium temperature and can be coated with a heat-resistance film. The heat resistance is improved by chemical crosslinking, and the main chain structure is not. Polar, sticky PP is good. Asahi Kasei developed SBBS Polystyrene (poly-1,4-butadiene-butene)-polystyrene, which has good thermal stability, soft segment Tg is 10 °C lower than SEBS, and excellent processing fluidity.
3, C5/C9 copolymer resin
Tackifying resins are an important component of HMPSA, and now also use a certain copolymerization ratio of C5/C9 petroleum resins, which can improve the compatibility with SIS, reduce the viscosity of pressure-sensitive adhesives, improve fast adhesion and low-temperature release properties.
4, acrylic HMPSA
Around 1980, the technology of pressure-sensitive adhesive made of acrylic hot melt adhesive attracted attention. With the development of acrylic copolymers, block copolymers and macromonomers, and the progress of cross-linking technology, Acrylic HMPSA has developed accordingly. , Overcoming some of the shortcomings of elastomer HMPSA in the past, such as thermal stability, seepage back, transparency and so on. Ren Jiaxiang et al studied the type and amount of butyl acrylate and 2-ethylhexyl acrylate, MMA or methyl acrylate, VAC, functional monomers (acrylic acid, maleic anhydride, acrylamide, etc.) for acrylic hot melt pressure sensitive adhesives. The impact of performance. The HMPSA can be prepared from an acrylate polymer containing OH or COOH, a blocked isocyanate and a quaternary ammonium salt, which can be melt-coated at 100-110°C and heated at 120-140°C after bonding. The macromonomer was prepared by the reaction of 2-hydroxyethyl methacrylate, phthalic anhydride and phenyl glycidyl ether, and then polymerized with 2-ethylhexyl acrylate to prepare HMPSA with good initial viscosity. Commodity ラクリメルト NO. 4580 is a acrylate copolymer, light yellow transparent, softening point 78 °C, can be 140% coating, direct coating of polyethylene. DuPont has developed phase-separated acrylic block copolymers that disperse acrylic hard blocks in an acrylic elastomer matrix. The two are thermodynamically immiscible. This structure has a thermally reversible physical cross-linking mechanism, heat-melt coating, and cooling. After curing, the block copolymer physically crosslinks. The copolymer is made of hydrogenated petroleum resin and hydrogenated rosin ester to make HMP-SA. It has good adhesion to various substrates (metals, plastics, polypropylenes), good thermal oxygen stability, and stable viscosity when melted.
Acrylic HMPSA will continue to be developed in the future. Through the synthesis of the main polymer, secondary processing and other means, it will develop a product with the same performance as the solvent-based acrylic pressure-sensitive adhesive.
5, UV/EB curing HMPSA
There are three problems with general UV/EB cured pressure-sensitive adhesives: 1 price: 2 on skin irritation and odor problems; 3 initial investment. However, the pressure-sensitive product market has recently turned to low VOC, high productivity, and high performance, opening new development opportunities for UV/EB-cured HMPSAs. Butyl acrylate-methyl acrylate-ethoxyethyl ethoxy diethylene glycol diacrylate copolymer (Tg-35 °C,
Mw125000) Add benzophenone to make HMPSA, coated on polyester film, after photocuring, the adhesive force is 12 N/25 mm, and the saturated polyester with end-acrylic group holding ≥1440 min is melt-coated at <100 °C , EB or UV irradiation, pressure-sensitive adhesive cross-linking reaction. PSA-705 (Kyoeisha Chemical) is an acrylic polyurethane HMPSA with a polyester skeleton, viscosity 70 Pa·s (120°C), Mw31000, low odor, low volatility, low toxicity, thermal stability, high-speed hardening, etc. . The Acrymelt UV industry began selling in 1998. The main component is an acrylate copolymer, a photoinitiator containing radical polymerization, and a 300-nm high-pressure mercury lamp that cures the pressure-sensitive adhesive. BASF uses benzophenone-based acrylic monomer copolymers Acronal DS3429, 3458 series, residual monomer <0.4%, developed a monomer-free HMPSA, to solve the problem of thermal stability. Shell developed the SIS cross-linked dedicated Siskronat-1320x. This star-shaped SIS is sensitive to EB radiation, and it does not lose its pressure-sensitive viscosity, temperature resistance, and solvent resistance after cross-linking.
In recent years, the cost of light-curing technology has been declining. Through comprehensive evaluation of the entire production process, UV-curable acrylic HM is superior to solvent-based acrylic glue; the total equipment investment cost of solvent-based, hot-melt, EB-HM, and production costs are compared. , EB/UV-curable HMPSA can be considered as an economically attractive technology
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