The glass transition temperature (Tg) of the designed composite polymer film should be high, ranging from 35℃ to 40℃. Methyl acrylate, styrene and acrylonitrile were selected as hard monomers. Ethyl acrylate and butyl acrylate are soft monomers. The mass ratio of soft and hard monomers is about 30:70. The mass fraction of itaconic acid should not exceed 3%. Generally, the mass fraction of N- hydroxymethyl acrylamide is less than 4%, the mass fraction of compound emulsifier is 2.5%~5.0%, and the mass ratio of non-anionic emulsifier to anionic emulsifier is 1:3.
Firstly, the mixed base material of part of monomer, emulsifier, buffer and deionized water is added into the reactor, stirred and heated, part of initiator is added at about 60℃, and heated to about 80℃ to initiate polymerization to prepare seed emulsion. When the natural heating is stopped and there is basically no reflux, the prepared pre-emulsion is added dropwise, and after 3-4 hours, the temperature is raised to nearly 90℃, the temperature is kept for 40-60 minutes, and the product is obtained after cooling and filtering.
High elastic cotton-sprayed adhesive is a white emulsion with a slight blue light, with a solid content of >: 40%, a pH value of 4~6, a viscosity of about 65438±08 MPa·s and a residual monomer content.
The glue-sprayed cotton is convenient to construct, and the glue-sprayed cotton products have high hardness, strong resilience, high permeability, strong adhesion and good water resistance. Far-infrared rubber-sprayed cotton is a fiber material made by coating ceramic powder with far-infrared radioactivity on the surface of fabric or mixing it with spinning dope. It belongs to active thermal insulation material, that is, it can meet the requirements of thermal insulation without increasing the thickness of thermal insulation layer. Far-infrared fabric is the abbreviation of a new type of warm-keeping and health-care fabric with high efficiency and far-infrared radioactivity. The research shows that far-infrared fabric can emit far-infrared rays with the wavelength of 4~ 14μm at normal body temperature, which matches the radiation wavelength of human far-infrared rays and is easily absorbed by human body, thus promoting blood vessel dilation, accelerating blood circulation, improving oxygen supply, enhancing cell regeneration ability and accelerating the excretion of harmful substances, thus gradually playing a health care role for human body. In addition, far-infrared fabrics also have antibacterial and deodorizing effects. There are two processing methods of far-infrared fabrics: the first is far-infrared fiber processing; The second is far infrared finishing. The far-infrared fabric processed by the former has good washability and hand feeling, but the processing route is long and the cost is high. The latter has a short processing route and low cost, but the handle and washing resistance of the fabric are not as good as the first processing method. Far-infrared substances are evenly and stably dispersed in the glue solution, so that they are attached to the surface of the fiber web together with the adhesive, thus achieving the purpose of far-infrared finishing with rubber-sprayed cotton. These two far infrared ceramic powders are MgO and Al2O3, respectively. After adding ceramic powder to the finishing liquid of rubber-sprayed cotton, the comprehensive properties of the fabric are required to be good. The so-called "comprehensive performance" includes the following aspects: ① the finished fabric has good heat insulation and radiation performance; (2) The finished fabric has a better hand feeling and no obvious roughness; ③ The finished fabric should be light in weight, so as to achieve the purpose of "thinness" of thermal insulation fabric.
When MgO and Al2O3 are mixed at the ratio of 60/40, the test results of 10% rubber-sprayed cotton have the best values in all aspects.
The technological process is as follows: cotton mixing → opening and cleaning → cotton mixing → carding → mechanical web forming → web forming → air web forming → pre-spraying → drying → post-spraying → drying → winding.
The trial-produced far-infrared rubber-sprayed cotton has a far-infrared emissivity of 80% in 8~ 15μm band, which has good warm-keeping and health-care functions. The raw materials of modified polyvinyl acetate cotton-sprayed adhesive are vinyl acetate (VAc), acrylic acid (AA), N- hydroxymethylacrylamide (N-HMAM), methyl methacrylate (MMA), butyl acrylate (BA), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), 0S- 15 and sodium bisulfite.
Core/shell emulsion polymerization process and redox catalytic system were adopted, and a small amount of water-resistant crosslinking monomer was added. By adjusting the order of monomer addition, the water resistance and elasticity of sprayed cotton glue were improved.
Synthesis process: put the mixed solution of deionized water, OS- 15 and part of NaHSO3-APS, and the mixed solution of 1/4 VAc and other monomers into a reactor, add an appropriate amount of disodium hydrogen phosphate to adjust the pH value to about 6, slowly raise the temperature to 65℃, keep the temperature for a while, and then start dropping the remaining 3/4 mixed monomers. The monomer and sodium bisulfite -APS solution are added simultaneously within 2-3 hours, then the temperature is raised to 75℃, the temperature is kept for 65+/-0 hours, the temperature is raised to 80℃, the temperature is kept for 30 minutes, then the temperature is lowered below 50℃, and the pH value is adjusted to 6-7.
The best formula is as follows: vac: 30 parts; AA: 0.9 copies; V-HMAM: 1. 1 copy; MMA: 6 copies; Ba: 2 copies; 0.15 ~ 0.25 part of SDS; SDBS, OS- 15: 0.5 copy; OP- 10，APS:0.2； Sodium bisulfite 3: 0. 1 serving; 60 parts of water.
It has a good effect on improving comprehensive properties such as water absorption, elasticity and hand feeling. The polymerization process is stable, the reflux is less, the reaction conversion rate is 95%~97%, the measured solid content is 40%, and the viscosity is about 6 MPa·s, which is suitable for rubber-sprayed cotton.