| With the prevalence of the network e-commerce industry,the express delivery industry has also developed rapidly,the cross-border transportation accounts for its considerable proportion,and the vast majority of transnational transportation is realized by sea.The wet marine environment is extremely easy to wet and damage the packaging cartons,make it collapses and lose its operational use.Surface sizing improves the printing line and adhesion of the sized paper.Commonly used surface sizing agents have the following types:Polyurethane(PU)and styrene-acrylate copolymer emulsion,etc.,styrene-acrylate copolymer emulsion as a rising star of surface sizing agent,with the excellent adhesion and film forming properties and its resistance to water,alkali and scrub is widely used in the surface sizing of paper.However,the styrene-acrylate copolymer emulsion surface sizing agent has limited hydrophobic ability,and the ring pressure strength of the sized paper is difficult to meet the requirements of the carton.Therefore,Seeking the ethylene-acrylate polymer emulsion surface sizing agents with high water resistance and high ring pressure strength have received increasing attention.In this paper,the styrene-acrylate copolymer emulsion was modified by introducing acrylamide as functional monomer,secondly,based on the styrene acrylic/acrylamide copolymer emulsion,different silane coupling agents were introduced to have it modified,and silane coupling was proposed.The physical model of the mechanism of the modified styrene-acrylic/acrylamide polymer emulsion and paper is proposed;the third discussion is introducing the stearyl methacrylate monomer to the previous P(St/BA/AM)copolymer emulsion and prepared P(St/BA/AM/SMA)copolymer emulsion,the results are as follows:(1)The acrylamide monomer was introduced into the styrene-acrylate emulsion system,and the styrene/acrylamide polymer emulsion was prepared by semi-continuous seed emulsion polymerization.The emulsion polymerization stability of P(St/BA/AM)copolymer was obtained.With the stability effect,the trend of increasing first and then decreasing,the amount of emulsifier has a certain influence on the stability of the emulsion.The St/BA ratio and the amount of AM have certain influence on the sizing performance of the copolymer emulsion.The best formula is found as:The polymerization temperature is 75°C,the amount of initiator is 8‰,the amount of emulsifier is 4%,the monomer ratio is St/BA=7:3,and the amount of AM is 15%.The polymer emulsion prepared under this condition has good stability and granules.The diameter is uniform and the particle morphology is regular.The water absorption of the latex film is only 30.21%.At the same time,the emulsion is used in the field of surface sizing agent,and the water droplet permeation time of the sized paper can reach 15.8s.(2)When the silane coupling agent(TEOS/MTES/ETES/OCTEOS)is modified with P(St/BA/AM)copolymer emulsion,the ring pressure strength of the modified emulsion sized paper increases with the addition of silane coupling agent.Big and big.(3)When tetraethyl silicate(TEOS)modified P(St/BA/AM)copolymer emulsion,the effect of adding directly to the corresponding sol prepared before adding to the reaction system is not much different;After adding a method,the effect of the length of the alkyl substituent of the silane coupling agent on the properties of the modified composite emulsion is as follows:the longer the alkyl substituent segment,the better the water resistance of the modified composite emulsion is,showing hydrophobicity.Performance methyl triethoxysilane(MTES)<ethyl triethoxysilane(ETES)<n-octyltriethoxysilane(OCTEOS);(4)When the silane coupling agent modified silane coupling agent modified P(St/BA/AM)emulsion sizing,the process of the sizing solution and the paper can be regarded as:low negative charge in the modified emulsion On the one hand,polysiloxane adsorbs on the surface of cationic nanoparticles due to electrostatic interaction,and can be effectively adsorbed with cationic nanoparticles and negatively charged paper fibers.On the other hand,these oligomeric siloxanes form oligomers of different sizes themselves.When the paper surface is sizing,the cationic nanoparticles carry part of the oligosiloxane to effectively adsorb to the negatively charged paper fibers,block the capillary pores between the fibers,reduce the penetration time of water droplets inside the paper,and thus increase the water resistance of the paper.Different sizes of oligosiloxane particles can also enter the paper fiber hole and support the paper from the inside of the paper to increase the strength of the paper.(5)When octadecyl acrylate(SMA)modified P(St/BA/AM)copolymer emulsion,AIBA is used as the water phase initiator and benzoyl peroxide(BPO)is used as the co-initiator.The modified emulsion prepared by the water-oil double initiation system has better stability.When used as a surface sizing agent,the water resistance of the sized paper is obviously improved,and the Cobb water absorption value of the sized paper is reduced by 0.45 g·m-2. |
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