Adhesive tape with a high degree of biomass
Adhesive tape is used, for example, to fix parts and elements that constitute mobile electronic terminals, cameras, personal computers, household appliances, automobiles and the like. Examples of raw materials used for such limb fixation adhesive tapes include silicone-based adhesives and acrylic-based adhesives. However, in the case of a silicone-based adhesive, it is not economical due to its high cost. On the other hand, in the case of acrylic adhesives, although the cost is low, oil is usually used as a raw material, so there are problems of depletion of oil resources and emission of carbon dioxide due to the disposal treatment.
In recent years, as interest in environmental issues such as global warming has increased, there has been a strong social demand for the use of plant-derived raw materials as an alternative to conventional petroleum-derived raw materials. However, it is difficult to meet the conventional required performance by using a raw material of plant origin, and a tape having a particularly high degree of biomass has the disadvantage of poor adhesiveness.
Therefore, an object of the present invention is to provide an adhesive tape having a high degree of biomass, having a sufficient adhesive force, and also having excellent detachability.
The present adhesive tape has a pressure-sensitive adhesive layer containing a polyester resin, the biomass grade of the pressure-sensitive adhesive layer is 80% by weight or more, the gel content of the pressure-sensitive adhesive layer pressure is 40% by weight and it is a stainless steel plate. Has an adhesive strength of 4 to 14 N/20 mm.
The pressure-sensitive adhesive composition according to the present invention contains a polyester-based resin. As the polyester resin, it is preferable to use at least a polyester obtained by polycondensing a carboxylic acid component and a diol component. The polyester synthesis method is not particularly limited, and a known polymerization method can be used.
The polyester is preferably produced from a plant-derived raw material. The reason is that the plant-derived raw material is said to be carbon-neutral, and it is possible to obtain an environmentally friendly adhesive that is friendly to the global environment.
The polyester contains a carboxylic acid component, and the carboxylic acid component preferably contains a dicarboxylic acid containing at least two carboxyl groups. Examples of the dicarboxylic acid include sebacic acid, azelaic acid, and isophthalic acid. The dicarboxylic acid can be used alone or in combination of two or more. Among them, sebacic acid and azelaic acid are particularly preferable from the viewpoint of being plant-derived and being friendly to the global environment.
In order to ensure the desired adhesiveness of the polyester resin, it is preferable to consider the equivalent number of the dicarboxylic acid and the diol component. For example, the blending ratio of the dicarboxylic acid component and the diol component is preferably in the range of 1 to 2 equivalents of the diol component per 1 equivalent of the dicarboxylic acid, and more preferably in the range of 1.1 to 1.7 equivalents.
For the polymerization (condensation polymerization) reaction of the carboxylic acid component and the diol component, conventionally known methods such as solvent-based and solvent-free can be used. A solvent-free system is particularly preferable from the viewpoint of environmental protection.
In order to form the pressure-sensitive adhesive layer, it is combining a pressure-sensitive adhesive together with a cross-linking agent with a polyester-based resin which is the main component of the pressure-sensitive adhesive.
The adhesive tape of the present invention may be provided with a base material. As the base material, for example, a non-woven fabric base material or a resin film may be used. Examples of the non-woven fabric base material include non-woven fabrics obtained by using chemical fibers such as Manila hemp, wood pulp, rayon, acetate fiber, polyester fiber, vinylon fiber (polyvinyl alcohol fiber), polyamide fiber, and a mixture thereof.
Preparation of polyester resin (A-1)) 0.14 equivalent of isophthalic acid as a dicarboxylic acid component, sebacic acid (derived from biomass) in a reaction can equipped with a thermometer, agitator, rectification tower, nitrogen introduction tube and vacuum device. ) 0.5 equivalent, 0.5 equivalent of azelaic acid (derived from biomass), 1.4 equivalent of ethylene glycol (derived from biomass) as a polyol component, 0.05 equivalent of diethylene glycol (derived from biomass), 0.0064% by weight of germanium dioxide as a catalyst Was charged, the temperature was gradually raised to an internal temperature of 250 ° C., and the esterification reaction was carried out over 4 hours. Then, the internal temperature was raised to 270 ° C. and the pressure was reduced to 1.33 hPa, and a polycondensation reaction was carried out over 3 hours to produce a polyester resin (A-1). The weight average molecular weight of the obtained polyester resin (A-1) was 138,000. The biomass degree of the polyester resin (A-1) was 92%.