阅读说明：本技术 一种具有抗菌功能的改性醋丙乳液粘合剂及其制备方法 (Modified vinyl acetate-acrylic emulsion adhesive with antibacterial function and preparation method thereof ) 是由 王经伟 王镇南 叶如兰 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种具有抗菌功能的改性醋丙乳液粘合剂及其制备方法,其制备步骤如下：向带有加热、电动搅拌、冷凝以及氮气导管的四口烧瓶中加入去离子水和聚乙烯醇,加热到后持续搅拌1-4h,再冷却到40-60℃,再然后加入缓冲液,再加入醋酸乙烯酯、丙烯酸丁酯、抗菌单体、改性山梨醇、叔碳酸乙烯酯,搅拌后升温,逐滴加入含引发剂的水溶液,滴加完毕后,继续反应得到抗菌功能的改性醋丙乳液粘合剂。本发明制得的粘合剂具有抗水性、抗热性,提高了共聚物的耐水性；引入经甲基丙烯酸异氰基乙酯改性的甘露糖苷作为抗菌功能单体,进而有效提升了醋丙乳液粘合剂的抗细菌粘附的效果。(The invention discloses a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function and a preparation method thereof, wherein the preparation method comprises the following steps: adding deionized water and polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensing and nitrogen guide pipe, heating, continuously stirring for 1-4h, cooling to 40-60 ℃, adding a buffer solution, adding vinyl acetate, butyl acrylate, an antibacterial monomer, modified sorbitol and vinyl versatate, stirring, heating, dropwise adding an aqueous solution containing an initiator, and continuously reacting to obtain the modified vinyl acetate-acrylic emulsion adhesive with the antibacterial function after dropwise adding. The adhesive prepared by the invention has water resistance and heat resistance, and improves the water resistance of the copolymer; the mannoside modified by the isocyano ethyl methacrylate is introduced as an antibacterial functional monomer, so that the antibacterial adhesion effect of the vinyl acetate-acrylic emulsion adhesive is effectively improved.)

1. A preparation method of a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function is characterized by comprising the following steps: the preparation steps are as follows:

adding 50-150mL of deionized water and 5-15g of polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensing and nitrogen guide pipe, heating to 70-100 ℃, continuously stirring for 1-4h, cooling to 40-60 ℃, then adding 0.1-1g of buffer solution, then adding 10-30g of vinyl acetate, 5-20g of butyl acrylate, 1.5-15g of antibacterial monomer, 3-7.5g of modified sorbitol and 1.5-4.5g of tertiary vinyl carbonate, stirring for 0.5-1h, heating to 70-85 ℃, dropwise adding 10-35mL of aqueous solution containing 0.5-1.5g of initiator, and continuously reacting for 3-6h after dropwise adding to obtain the modified vinyl acetate-acrylate emulsion adhesive with the antibacterial function.

2. The method of claim 1, wherein: the preparation method of the antibacterial monomer comprises the following steps: reacting mannoside with isocyano ethyl methacrylate at room temperature, taking 50-150mL of dichloromethane as a reaction solvent, and reacting for 72h to obtain an antibacterial monomer; wherein the molar ratio of the added mannoside to the isocyano ethyl methacrylate is 0.1-1: 0.025-0.25.

3. The method of claim 1, wherein: the preparation method of the modified sorbitol comprises the following steps: dissolving sorbitol in 50-150mL tetrahydrofuran or cyclohexane solution, gradually adding isocyano ethyl methacrylate, stirring and heating the reaction mixture, reacting at 90 ℃ for 24 hours, stirring and heating to react to obtain modified sorbitol; wherein the molar ratio of the added sorbitol to the isocyano ethyl methacrylate is 2-3.5: 0.3-0.58.

4. The method of claim 2, wherein: the mannoside is one or more of alpha-methyl-D-mannoside, 4-isothiohydrogen phenyl-alpha-D-mannoside and 4-methyl umbelliferyl alpha-D-mannopyranoside.

5. The method of claim 1, wherein: the buffer solution is an aqueous solution of sodium acetate and ferrous sulfate in a weight ratio of 1: 2.

6. The method of claim 1, wherein: the initiator is one or more of 1.0% of dioxygen/tartaric acid, ammonium persulfate/sodium bisulfite and potassium persulfate/sodium bisulfite.

7. A modified vinyl acetate-acrylic emulsion adhesive having an antibacterial function, which is prepared by the preparation method according to any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of adhesives, in particular to a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function and a preparation method thereof.

Background

With the increase of awareness of health and environmental protection, people advocate the production of green products, which also include adhesives. Statistically, the wood adhesive industry is currently using petrochemical derived resins for the production of, for example, Melamine Urea Formaldehyde (MUF), Phenol Formaldehyde (PF) and Urea Formaldehyde (UF), which are materials that are harmful to us. It is therefore reasonable and promising to develop environmentally friendly materials as a substitute for wood adhesives.

The polyvinyl acetate emulsion is an aqueous environment-friendly adhesive, is commonly called white latex, has low cost, simple polymerization process, no odor, no toxicity, no color, transparency, good bonding property, difficult aging, light resistance and the like. Due to its excellent properties, polyvinyl acetate emulsion is used as an initial protective colloid for emulsion polymerization, can be grafted by other monomers, and is widely applied to a plurality of fields such as wood adhesion, paper processing, building coating, textile printing and dyeing, cement modification, glass fiber processing, home decoration and the like. However, the polyvinyl acetate emulsion has disadvantages such as poor water resistance, poor heat resistance, and poor mechanical stability. Exterior wall coatings which are subjected to sunlight irradiation and wind, wind and rain for a long time and interior wall coatings which are used in indoor humid environments such as sanitation and kitchens all have the equivalent water resistance. In order to apply polyvinyl acetate emulsion in different fields, people usually modify the polyvinyl acetate emulsion, such as blending, copolymerization, crosslinking, protective colloid modification and the like, so as to meet the service performance. With the wide application of polyvinyl acetate emulsion in the industries of high-grade furniture, automobile interior decoration, automobile tarpaulin and the like, people have higher requirements on heat resistance, non-toxicity and environmental protection performance of the polyvinyl acetate emulsion, and the effect of the existing modification method is still not ideal. Therefore, the development of a polyvinyl acetate emulsion coating which has better water resistance and thermal stability and is easy to be multifunctional is gradually in the trend. The invention improves the original defects of poor water resistance, thermal stability and the like by adding the antibacterial adhesion performance to the polyvinyl acetate emulsion, thereby improving the application range and the utilization rate of the polyvinyl acetate emulsion in the market.

Disclosure of Invention

The invention aims to prepare an adhesive with good water resistance and strong thermal stability.

In order to achieve the purpose, the invention provides the following technical scheme:

a preparation method of a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function comprises the following preparation steps:

adding 50-150mL of deionized water and 5-15g of polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensing and nitrogen guide pipe, heating to 70-100 ℃, continuously stirring for 1-4h, cooling to 40-60 ℃, then adding 0.1-1g of buffer solution, then adding 10-30g of vinyl acetate, 5-20g of butyl acrylate, 1.5-15g of antibacterial monomer, 3-7.5g of modified sorbitol and 1.5-4.5g of tertiary vinyl carbonate, stirring for 0.5-1h, heating to 70-85 ℃, dropwise adding 10-35mL of aqueous solution containing 0.5-1.5g of initiator, and continuously reacting for 3-6h after dropwise adding to obtain the modified vinyl acetate-acrylate emulsion adhesive with the antibacterial function.

Preferably, the preparation method of the antibacterial monomer comprises the following steps: reacting mannoside with isocyano ethyl methacrylate at room temperature, taking 50-150mL of dichloromethane as a reaction solvent, and reacting for 72h to obtain an antibacterial monomer; wherein the molar ratio of the added mannoside to the isocyano ethyl methacrylate is 0.1-1: 0.025-0.25.

Preferably, the preparation method of the modified sorbitol comprises the following steps: dissolving sorbitol in 50-150mL tetrahydrofuran or cyclohexane solution, gradually adding isocyano isopropyl methacrylate, stirring and heating the reaction mixture, reacting at 90 ℃ for 24 hours, stirring and heating to react to obtain modified sorbitol; wherein the molar ratio of the added sorbitol to the isocyano ethyl methacrylate is 2-3.5: 0.3-0.58.

Preferably, the mannoside is one or more of alpha-methyl-D-mannoside, 4-isothiohydrogen phenyl-alpha-D-mannoside and 4-methylumbelliferyl alpha-D-mannopyranoside.

Preferably, the buffer is an aqueous solution of sodium acetate and ferrous sulfate in a weight ratio of 1: 2.

Preferably, the initiator is one or more of 1.0% hydrogen peroxide/tartaric acid, ammonium persulfate/sodium bisulfite and potassium persulfate sodium bisulfite.

The modified vinyl acetate-acrylic emulsion adhesive with the antibacterial function is prepared according to the preparation method.

Compared with the prior art, the invention has the beneficial effects that:

1. compared with the traditional wood adhesive which is based on Melamine Urea Formaldehyde (MUF), Phenol Formaldehyde (PF) and Urea Formaldehyde (UF), the wood adhesive of the invention is based on polyvinyl acetate emulsion, polyvinyl alcohol has a simple linear structure, so that molecular chains are soft, rotation is facilitated, the fluidity of the adhesive is improved, and the adhesive strength is relatively higher compared with other adhesives. On the basis of the original base, the invention further improves the performance of VAc homopolymerized emulsion, and improves the shear bonding strength of the emulsion, the water resistance and the heat resistance of a glue film possibly by carrying out binary or multiple emulsion copolymerization on the VAc and modified monomers such as Butyl Acrylate (BA), vinyl versatate (VeoVa) and the like and adding a sorbitol modifier.

2. The vinyl versatate is added into the polyvinyl acetate emulsion to carry out binary or multi-component emulsion copolymerization as a modified monomer, the vinyl versatate is a modified monomer with excellent water resistance, and is copolymerized with the vinyl acetate emulsion to fully show the modification effect of the vinyl versatate.

3. According to the invention, the sorbitol modifier is added into the polyvinyl acetate emulsion, sorbitol is introduced into the vinyl acetate-acrylic emulsion adhesive, namely, isocyano ethyl methacrylate and sorbitol are added into tetrahydrofuran or cyclohexane solution to react, so that one end of the modifier is provided with isocyano and the other end is provided with double bonds, and the purpose of improving the defect of poor original thermal stability is achieved.

4. In the polyvinyl acetate emulsion, the problem that sorbitol has a plurality of hydroxyl groups to cause the preparation of high-function linear polyester to be challenging is solved, the esterification reaction is limited on two primary hydroxyl groups in the experiment, four secondary hydroxyl groups contained in the sorbitol are not influenced, the integrity and the linearity of the obtained polyester are ensured, chain pendant secondary hydroxyl groups which can be left behind are further modified and can be used as new reaction sites to form a cross-linking network with other active functional groups or new components can be introduced, and the possibility of further introducing new functional functions into the adhesive is increased.

5. In the polyvinyl acetate emulsion, on one hand, because a plurality of hydroxyl groups exist in sorbitol, the hydroxyl groups participate in esterification and polycondensation reactions in polymerization reaction, and part of the hydroxyl groups are still exposed on the surface, thereby promoting the crystallization of the adhesive, leading the adhesive to be easy to form soft and hard segments, and along with the formation of the soft and hard segments, the content of the hard segments is relatively reduced, one NCO group participating in the reaction is reduced, leading the rigid segments to be reduced, the content of the soft segments to be increased, leading the mutual winding among molecules to be increased, and further improving the bonding strength of the adhesive. On the other hand, the mannoside modified by the isocyano ethyl methacrylate can better play a role in resisting bacteria adhesion, so that the adhesive is prevented from mildewing in the application process, and the service life of the adhesive is prolonged.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

(1) preparing an antibacterial monomer: reacting 10g of alpha-methyl-D-mannoside with 1.9g of isocyano ethyl methacrylate at room temperature, taking 50mL of dichloromethane as a reaction solvent, and reacting for 72h to obtain the antibacterial monomer.

(2) Preparation of modified sorbitol: 10g of sorbitol was dissolved in 50mL of tetrahydrofuran or cyclohexane solution, 1.2g of isocyanoisopropyl methacrylate was gradually added thereto, the reaction mixture was heated with stirring, reacted at 90 ℃ for 24 hours with stirring and heating.

(3) Preparing a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function: adding 50mL of deionized water and 5g of polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensation and nitrogen guide pipe, heating to 70 ℃, continuously stirring for 1h, cooling to 40 ℃, adding 0.1g of buffer solution, wherein the buffer solution is an aqueous solution of sodium acetate and ferrous sulfate in a weight ratio of 1:2, adding 10g of vinyl acetate, 5g of butyl acrylate, 1.5g of antibacterial monomer, 3g of modified sorbitol and 1.5g of vinyl versatate, stirring for 0.5h, heating to 70 ℃, and dropwise adding 10mL of 0.5g of 1.0% hydrogen peroxide/tartaric acid aqueous solution. And after the dropwise addition is finished, continuously reacting for 3 hours to obtain a product.

Example 2:

1) preparing an antibacterial monomer: reacting 15g of 4-isothiohydrogen phenyl-alpha-D-mannoside with 2.85g of isocyanoethyl methacrylate at room temperature, and taking 100mL of dichloromethane as a reaction solvent to react 72 to obtain an antibacterial monomer h.

2) Preparation of modified sorbitol: 20g of sorbitol was dissolved in 100mL of tetrahydrofuran or cyclohexane solution, 2.4g of isocyanoisopropyl methacrylate was gradually added thereto, the reaction mixture was heated with stirring, reacted at 90 ℃ for 24 hours with stirring and heating.

3) Preparing a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function: adding 100mL of deionized water and 10g of polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensation and nitrogen guide pipe, heating to 70 ℃, continuously stirring for 2h, cooling to 50 ℃, adding 0.5g of buffer solution, wherein the buffer solution is an aqueous solution of sodium acetate and ferrous sulfate in a weight ratio of 1:2, adding 20g of vinyl acetate, 10g of butyl acrylate, 3g of antibacterial monomer, 6g of modified sorbitol and 3g of tertiary ethylene carbonate, stirring for 1h, heating to 80 ℃, and dropwise adding 20mL of an aqueous solution containing 1.0g of ammonium persulfate/sodium bisulfite. After the dropwise addition is finished, the reaction is continued for 4 hours to obtain a product.

Example 3:

1) preparing an antibacterial monomer: reacting 20g of 4-methylumbelliferyl alpha-D-mannopyranoside with 3.8g of isocyanoethyl methacrylate at room temperature, and taking 150mL of dichloromethane as a reaction solvent to react for 72h to obtain the antibacterial monomer.

2) Preparation of modified sorbitol: after 30g of sorbitol was dissolved in 150mL of tetrahydrofuran or cyclohexane solution, 3.6g of isocyanoisyl methacrylate was gradually added, the reaction mixture was heated with stirring, reacted at 90 ℃ for 24 hours with stirring and heated.

3) Preparing a modified vinyl acetate-acrylic emulsion adhesive with an antibacterial function: adding 150mL of deionized water and 15g of polyvinyl alcohol into a four-neck flask with a heating, electric stirring, condensation and nitrogen guide pipe, heating to 70 ℃, continuously stirring for 4h, cooling to 40 ℃, adding 0.3g of buffer solution, wherein the buffer solution is an aqueous solution of sodium acetate and ferrous sulfate in a weight ratio of 1:2, adding 30g of vinyl acetate, 15g of butyl acrylate, 4.5g of antibacterial monomer, 9g of modified sorbitol and 4.5g of tertiary ethylene carbonate, stirring for 1.5h, heating to 85 ℃, and dropwise adding 10mL of an aqueous solution containing 1.5g of potassium persulfate and sodium bisulfite. And after the dropwise addition is finished, continuously reacting for 6 hours to obtain a product.

And (3) performance testing:

first, the adhesive of this example was tested for adhesive performance, anti-bacterial adhesion, and water resistance

The detection method of the adhesive property and the water resistance property comprises the following steps: the control, example 1, example 2, example 3, was tested by preparing a number of pieces of wood having a width of 20mm and a length of the appropriate amount, and applying the emulsion to the pieces of wood in an area of 20mm x 15 mm. Bonding the two wood chips, naturally drying, and respectively measuring the dry state and the soaking water for 24h, wherein the dry compressive shear strength is obtained, and the tensile rate of a tensile machine is 200 mm/min.

Secondly, the detection method for resisting bacterial adhesion comprises the following steps: the test control group, the example 1, the example 2 and the example 3 use three test samples to bond wood with the same property in a trace oxygen or high humidity environment, and after 24 days, the surfaces of the wood are observed to be mildewed due to different antibacterial agent contents;

the control group was a commercially available starch adhesive, and the performance of the adhesive was compared with that of the adhesive of this example to obtain tables 1 and 2 below.

The results of the analysis of the tables 1 and 2 show that the adhesive provided by the invention has outstanding bonding performance and very excellent water resistance.

The adhesive provided by the invention is not easy to mildew or mildew under the environment of trace oxygen or high humidity, and compared with a blank control, the adhesive effectively weakens the bacteria adsorption capacity.

TABLE 1 Effect of VeoValO and sorbitol modifiers on bond strength

Group counting/testing method	Dry state compression shear strength/Mpa	Compressive shear strength/Mpa after soaking in water
			Control group	2.10	0.80
Example 1	3.82	3.25
			Example 2	3.84	3.27
Example 3	3.86	3.29

TABLE 2 Effect of antimicrobial content on the mildew resistance of the adhesive

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that the present embodiments be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.