CN113462238A - Modified PVA emulsion and preparation method thereof, and composite cellophane and preparation method thereof - Google Patents
Modified PVA emulsion and preparation method thereof, and composite cellophane and preparation method thereof Download PDFInfo
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- CN113462238A CN113462238A CN202110858948.0A CN202110858948A CN113462238A CN 113462238 A CN113462238 A CN 113462238A CN 202110858948 A CN202110858948 A CN 202110858948A CN 113462238 A CN113462238 A CN 113462238A
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- 239000000839 emulsion Substances 0.000 title claims abstract description 86
- 229920000298 Cellophane Polymers 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- 239000002131 composite material Substances 0.000 title claims abstract description 21
- 238000004945 emulsification Methods 0.000 title description 2
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000003607 modifier Substances 0.000 claims abstract description 17
- 239000003054 catalyst Substances 0.000 claims abstract description 16
- 239000004594 Masterbatch (MB) Substances 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 14
- 239000002518 antifoaming agent Substances 0.000 claims abstract description 13
- 238000000576 coating method Methods 0.000 claims description 38
- 239000011248 coating agent Substances 0.000 claims description 35
- 238000006243 chemical reaction Methods 0.000 claims description 29
- 238000004132 cross linking Methods 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 11
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 9
- 239000008234 soft water Substances 0.000 claims description 9
- 239000011086 glassine Substances 0.000 claims description 8
- 239000011521 glass Substances 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N alpha-ketodiacetal Natural products O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000009833 condensation Methods 0.000 claims description 6
- 230000005494 condensation Effects 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 239000000123 paper Substances 0.000 claims description 5
- 239000005057 Hexamethylene diisocyanate Substances 0.000 claims description 4
- 239000005058 Isophorone diisocyanate Substances 0.000 claims description 4
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 claims description 4
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims description 3
- KXBFLNPZHXDQLV-UHFFFAOYSA-N [cyclohexyl(diisocyanato)methyl]cyclohexane Chemical compound C1CCCCC1C(N=C=O)(N=C=O)C1CCCCC1 KXBFLNPZHXDQLV-UHFFFAOYSA-N 0.000 claims description 3
- 238000006136 alcoholysis reaction Methods 0.000 claims description 3
- 239000012295 chemical reaction liquid Substances 0.000 claims description 3
- 229940015043 glyoxal Drugs 0.000 claims description 3
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical group [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- 239000011247 coating layer Substances 0.000 claims description 2
- 230000004888 barrier function Effects 0.000 abstract description 13
- 239000000853 adhesive Substances 0.000 abstract description 9
- 230000001070 adhesive effect Effects 0.000 abstract description 9
- 239000004372 Polyvinyl alcohol Substances 0.000 description 34
- 229920002451 polyvinyl alcohol Polymers 0.000 description 34
- 238000003756 stirring Methods 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229920003023 plastic Polymers 0.000 description 6
- 239000004033 plastic Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 239000013530 defoamer Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000005033 polyvinylidene chloride Substances 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 125000003172 aldehyde group Chemical group 0.000 description 2
- 238000005882 aldol condensation reaction Methods 0.000 description 2
- XLJMAIOERFSOGZ-UHFFFAOYSA-N anhydrous cyanic acid Natural products OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- -1 polysiloxane Polymers 0.000 description 2
- 229920003225 polyurethane elastomer Polymers 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000008104 plant cellulose Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
- C09D129/02—Homopolymers or copolymers of unsaturated alcohols
- C09D129/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/60—Additives non-macromolecular
- C09D7/63—Additives non-macromolecular organic
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Paints Or Removers (AREA)
Abstract
The invention provides a modified PVA emulsion and a preparation method thereof, and composite cellophane and a preparation method thereof. The modified PVA emulsion provided by the invention is prepared from the following raw materials in percentage by mass: 8% -15% of PVA master batch; 70-85% of water; 0.2 to 2 percent of catalyst; 2 to 10 percent of cross-linking agent; 1.5 to 3 percent of modifier; 0.5 to 2 percent of defoaming agent. The modified PVA emulsion provided by the invention has good degradability, and can effectively improve the barrier property and the adhesive force to the cellophane.
Description
Technical Field
The invention relates to the field of high polymer materials, and particularly relates to a modified PVA emulsion and a preparation method thereof, as well as composite cellophane and a preparation method thereof.
Background
Plastic bags are consumable items in daily life, and a large number of plastic bags are consumed every year. It provides convenience for consumers, and causes serious resource waste and environmental pollution due to excessive use, improper recovery and treatment and the like. Particularly, the ultrathin plastic shopping bags are easy to damage, most of the ultrathin plastic shopping bags are randomly discarded, and the ultrathin plastic shopping bags become a main source of white pollution. More and more countries and regions have limited the production, sale, use of plastic shopping bags.
The cellophane is also called cellophane, is made of plant cellulose as raw material, has good performances of degradability, static resistance and the like, and can be applied to the field of food packaging. Chinese patent application CN200980139574 discloses a polysiloxane composition which can be used for coating glassine paper, and can form a crosslinked coating on the glassine paper with improved adhesion, mechanical strength and reactivity, but does not relate to improving the barrier property of the glassine paper, and the barrier property of food packaging for packaging materials is high, but the barrier property of the glassine paper at present cannot meet the required requirement. Chinese patent application CN103059200A discloses a PVDC emulsion for coating cellophane, which has excellent oxygen and water blocking effects, but the cellophane with PVDC coating is difficult to naturally degrade, and when incinerated, the waste can generate hydrogen chloride, dioxin and other substances which are toxic and harmful to human body and surrounding environment. In view of the above environmental problems, countries such as europe and the united states are gradually replacing PVDC coatings with environmental protection materials. Patent application CN10230414A discloses a water-resistant barrier polyvinyl alcohol coating for coating and a preparation method thereof, wherein a degradable PVA material is adopted as a coating material, and although the coating material has good degradability and improves the barrier property to a certain extent, the oxygen-blocking and water-blocking effects of the coating material can not meet the increasing requirement on the barrier property.
Disclosure of Invention
In view of the above, the present invention aims to provide a modified PVA emulsion and a preparation method thereof, and a composite cellophane and a preparation method thereof. The modified PVA emulsion provided by the invention has good degradability, and can effectively improve the barrier property and the adhesive force to the cellophane.
The invention provides a modified PVA emulsion which is prepared from the following raw materials in percentage by mass:
preferably, the modifier is selected from one or more of isophorone diisocyanate, dicyclohexyl methane diisocyanate and hexamethylene diisocyanate.
Preferably, the catalyst is potassium persulfate and/or sodium persulfate.
Preferably, the cross-linking agent is glyoxal and/or glutaraldehyde.
Preferably, the defoaming agent is ethanol and/or ethylene glycol;
the polymerization degree of the PVA master batch is 500-2000, and the alcoholysis degree is 80-99%;
the water is soft water.
The invention also provides a preparation method of the modified PVA emulsion in the technical scheme, which comprises the following steps:
a) mixing and heating the PVA master batch and water for dissolving to obtain PVA dissolving liquid;
b) mixing the PVA solution with a catalyst and a cross-linking agent to carry out condensation cross-linking reaction to obtain a cross-linking reaction solution;
c) and mixing the crosslinking reaction liquid with a modifier and a defoaming agent to obtain the modified PVA emulsion.
Preferably, in the step a), the heating and dissolving temperature is 100-110 ℃, and the time is 2-3 hours.
Preferably, in the step b), the temperature of the crosslinking reaction is 70-75 ℃ and the time is 0.5-1 h.
The invention also provides composite cellophane, which comprises cellophane and a coating compounded on the surface of the cellophane;
the coating is formed by the modified PVA emulsion in the technical scheme or the modified PVA emulsion prepared by the preparation method in the technical scheme.
The invention also provides a preparation method of the composite cellophane in the technical scheme, which comprises the following steps:
after the emulsion is coated on the upper surface of the glass, drying to form a coating, and obtaining the composite glass paper;
the emulsion is the modified PVA emulsion in the technical scheme or the modified PVA emulsion prepared by the preparation method in the technical scheme.
The modified PVA emulsion is prepared by matching PVA master batch, water, a catalyst, a cross-linking agent, a modifying agent and a defoaming agent according to a certain proportion, polyvinyl alcohol is heated and dissolved in soft water, and then the cross-linking agent is added under the action of the catalyst, so that active carboxyl in the emulsion and aldehyde group in the cross-linking agent are subjected to aldol condensation reaction to generate a new beta-hydroxyketone compound, the molecules of the emulsion are more compact, and the barrier property of a coating is improved to a certain extent. Meanwhile, the self groups of the cross-linking agent are utilized to shield the hydroxyl groups in the polyvinyl alcohol molecules, so that the affinity effect of the hydroxyl groups with water is reduced, the linear polyvinyl alcohol molecules are mutually connected to form a net structure, and the adhesive force of the coating and the cellophane is improved. After the emulsion completely reacts, a proper amount of antifoaming agent and modifier are added to eliminate foam and adjust the surface tension of the emulsion system, so that better and more uniform coating is facilitated, and after the emulsion is subjected to crosslinking reaction, the added modifier contains isocyanic acid radical with unsaturated bonds and reacts with carboxyl contained in the PVA emulsion to generate a polyurethane elastomer, so that the adhesive force of the emulsion to the cellophane is improved.
Experimental results show that the modified PVA emulsion provided by the invention enables the oxygen transmission rate of the cellophane to be reduced to 5cc/m2Day below, water vapor transmission rate reduced to 10g/m2And the adhesion between the coating and the cellophane is improved to more than grade 1 below day.
Detailed Description
The invention provides a modified PVA emulsion which is prepared from the following raw materials in percentage by mass:
in the invention, the PVA master batch (namely polyvinyl alcohol) is preferably PVA with the polymerization degree of 500-2000 and the alcoholysis degree of 80-99%. In the invention, the mass ratio of the PVA master batch in the raw materials is 8-15%; in some embodiments of the invention, the mass ratio is 8%, 11% or 15%.
In the present invention, the catalyst is preferably potassium persulfate and/or sodium persulfate. In the invention, the mass ratio of the catalyst in the raw materials is 0.2-2%; in some embodiments of the invention, the mass ratio is 1%, 1.5% or 2%.
In the present invention, the crosslinking agent is preferably glyoxal and/or glutaraldehyde. In the invention, the mass ratio of the cross-linking agent in the raw materials is 2-10%; in some embodiments of the invention, the mass ratio is 3%, 8% or 10%.
In the invention, the modifier is preferably one or more of isophorone diisocyanate (i.e. IPDI), dicyclohexylmethane diisocyanate (i.e. HMD) and hexamethylene diisocyanate (i.e. HDI). In the invention, the mass ratio of the modifier in the raw materials is 1.5-3%; in some embodiments of the invention, the mass ratio is 1.5%, 2.5% or 3%.
In the present invention, the antifoaming agent is preferably ethanol and/or ethylene glycol. In the invention, the mass ratio of the defoaming agent in the raw materials is 0.5-2%; in some embodiments of the invention, the mass ratio is 0.5%, 1%, or 2%.
In the present invention, the water is preferably soft water. In the invention, the mass ratio of the soft water in the raw material is 70-85%; in some embodiments of the invention, the mass ratio is 70%, 75% or 85%.
In the invention, the solid content of the modified PVA emulsion is 15-20%. In the prior art, the solid content of the emulsion generally only reaches the level of 5-7 percent, the invention improves the solid content of the emulsion, can improve the uniformity of a coating during coating, and is beneficial to better blocking oxygen and water vapor.
The invention also provides a preparation method of the modified PVA emulsion in the technical scheme, which comprises the following steps:
a) mixing and heating the PVA master batch and water for dissolving to obtain PVA dissolving liquid;
b) mixing the PVA solution with a catalyst and a cross-linking agent to carry out condensation cross-linking reaction to obtain a cross-linking reaction solution;
c) and mixing the crosslinking reaction liquid with a modifier and a defoaming agent to obtain the modified PVA emulsion.
The types, the amounts and the like of the PVA master batch, the water, the catalyst, the cross-linking agent, the modifier and the defoaming agent are consistent with those in the technical scheme, and are not described in detail herein.
With respect to step a):
in the present invention, the heating and dissolving are preferably performed under a protective atmosphere. The type of protective gas used to provide the protective atmosphere is not particularly limited in the present invention and may be any conventional inert gas known to those skilled in the art, such as nitrogen or argon. In the present invention, the pressure of the protective gas is preferably 1 to 2 MPa. In the invention, the heating and dissolving temperature is preferably 100-110 ℃, and the time is preferably 2-3 h. In the present invention, stirring is preferably accompanied in the heating and dissolving process; the stirring speed is preferably 150-200 r/min. The PVA solution is obtained by heating and dissolving.
With respect to step b):
in the invention, the temperature of the condensation crosslinking reaction is preferably 70-75 ℃, specifically, after the heating and the dissolution in the step a) are completed, the temperature of the system is reduced to 70-75 ℃, then a catalyst and a crosslinking agent are added, and the condensation crosslinking reaction is carried out under the temperature. The reaction for sealing the hydroxyl groups can be effectively and rapidly carried out at the temperature, and an ideal effect is achieved. In the invention, the reaction time is preferably 0.5-1 h.
With respect to step c):
in the invention, the mixing temperature is preferably 70-75 ℃, namely after the condensation crosslinking reaction in the step b) is finished, the modifier and the defoaming agent are added and mixed under the same condition. In the present invention, the mixing is preferably performed by stirring; the stirring speed is preferably 150-200 r/min; the stirring time is preferably 1-2 h. After the materials are fully mixed by the treatment, the mixture is stood, cooled to room temperature and discharged, and the modified PVA emulsion is obtained.
The invention controls the feeding and reaction steps to effectively match the front reaction and the back reaction, thereby improving the adhesive force and the barrier property of the product. In the invention, the solid content of the modified PVA emulsion is 15-20%. In the prior art, the solid content of the emulsion generally only reaches the level of 5-7%, and the PVA master batch with low polymerization degree molecular weight is selected and dissolved under a specific dissolving process at high temperature and high pressure in a protective gas atmosphere, so that the solid content of the emulsion is improved, the uniformity of a coating can be improved during coating, and the barrier property is favorably improved.
In the preparation process, after the polyvinyl alcohol is heated and dissolved in the soft water, the crosslinking agent is added under the action of the catalyst, and the active carboxyl in the emulsion and the aldehyde group in the crosslinking agent are subjected to aldol condensation reaction to generate a new beta-hydroxyketone compound, so that the emulsion molecules are more compact, and the barrier property of the coating is improved to a certain extent. Meanwhile, the self groups of the cross-linking agent are utilized to shield the hydroxyl groups in the polyvinyl alcohol molecules, so that the affinity effect of the hydroxyl groups with water is reduced, the linear polyvinyl alcohol molecules are mutually connected to form a net structure, and the adhesive force of the coating and the cellophane is improved. After the emulsion completely reacts, a proper amount of antifoaming agent and modifier are added to eliminate foam and adjust the surface tension of the emulsion system, so that better and more uniform coating is facilitated, and after the emulsion is subjected to crosslinking reaction, the added modifier contains isocyanic acid radical with unsaturated bonds and reacts with carboxyl contained in the PVA emulsion to generate a polyurethane elastomer, so that the adhesive force of the emulsion to the cellophane is improved.
The modified PVA emulsion provided by the invention is an emulsion for cellophane, and can improve the barrier property and the adhesive force of the cellophane.
The invention also provides composite cellophane, which comprises cellophane and a coating compounded on the surface of the cellophane; the coating is formed by the modified PVA emulsion in the technical scheme or the modified PVA emulsion prepared by the preparation method in the technical scheme.
The invention also provides a preparation method of the composite cellophane in the technical scheme, which comprises the following steps:
after the emulsion is coated on the upper surface of the glass, drying to form a coating, and obtaining the composite glass paper;
the emulsion is the modified PVA emulsion in the technical scheme or the modified PVA emulsion prepared by the preparation method in the technical scheme.
In the present invention, the kind of the cellophane is not particularly limited, and may be a cellophane that is conventional in the art. The specification of the cellophane is preferably 60-100 g/m2. In the present invention, the coating method of the emulsion is not particularly limited, and may be a conventional coating method in the art. In the invention, the coating weight of the emulsion is preferably 3-5 g/m2. In the invention, the drying temperature is preferably 90-120 ℃. The thickness of the coating is preferably 3-5 μm. And drying to form a coating to obtain the composite cellophane.
Experimental results show that the modified PVA emulsion provided by the invention enables the oxygen transmission rate of the cellophane to be reduced to 5cc/m2Day below, water vapor transmission rate reduced to 10g/m2And the adhesion between the coating and the cellophane is improved to more than grade 1 below day.
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Example 1
1. The raw material formula of the modified PVA emulsion comprises:
2. preparation of modified PVA emulsion:
adding soft water and PVA master batch into a reaction kettle, sealing a feeding hole, introducing nitrogen into the reaction kettle at the air pressure of 1.0MPa, starting stirring at the speed of 200r/min, and heating to 100 ℃ for 3 hours to completely dissolve PVA. And then, cooling to 70 ℃, adding a catalyst and a crosslinking agent, and carrying out heat preservation reaction for 0.5h to ensure that the crosslinking reaction is complete. And finally, keeping the temperature, adding the modifier and the defoamer, fully stirring for 2 hours, standing, cooling to room temperature, and discharging to obtain the modified PVA emulsion.
Example 2
1. The raw material formula of the modified PVA emulsion comprises:
2. preparation of modified PVA emulsion:
adding soft water and PVA master batch into a reaction kettle, sealing a feeding hole, introducing nitrogen into the reaction kettle at the air pressure of 1.5MPa, starting stirring at the speed of 170r/min, and heating to 105 ℃ for 2.5 hours to completely dissolve PVA. And then, cooling to 73 ℃, adding a catalyst and a crosslinking agent, and carrying out heat preservation reaction for 0.7h to ensure that the crosslinking reaction is complete. And finally, keeping the temperature, adding the modifier and the defoamer, fully stirring for 1.5h, standing, cooling to room temperature, and discharging to obtain the modified PVA emulsion.
Example 3
1. The raw material formula of the modified PVA emulsion comprises:
2. preparation of modified PVA emulsion:
adding soft water and PVA master batch into a reaction kettle, sealing a feeding hole, introducing nitrogen into the reaction kettle at the air pressure of 2.0MPa, starting stirring at the speed of 150r/min, and heating to 110 ℃ for 2 hours to completely dissolve PVA. And then, cooling to 75 ℃, adding a catalyst and a crosslinking agent, and carrying out heat preservation reaction for 1h to ensure that the crosslinking reaction is complete. And finally, keeping the temperature, adding the modifier and the defoamer, fully stirring for 1h, standing, cooling to room temperature, and discharging to obtain the modified PVA emulsion.
Example 4
1. Preparation of composite glassine paper
Taking the density of 100g/m2The emulsion was coated on one surface of a glassine paper (thickness: 50 μm) in an amount of 6g/m2After coating, the coated paper was dried at 110 ℃ for 6 seconds to form a coating layer (thickness: 4 μm), thereby obtaining a composite cellophane paper.
The modified PVA emulsions obtained in the embodiments 1-3 of the invention and the control PVA emulsion are respectively prepared into the composite cellophane according to the processes. Wherein, the comparison PVA emulsion is the emulsion paint obtained in the prior art CN102304314A in the example 2, and the composite glass paper prepared by coating the emulsion is marked as the comparison example 1.
2. Performance testing
The oxygen transmission rate of the composite cellophane sample is tested by referring to the national standard GB/T1038, wherein the testing conditions are that the temperature is 23 ℃ and the humidity is 0% RH. The water vapor transmission rate of the composite cellophane sample is tested by referring to the national standard GB/T1037, wherein the testing conditions are that the temperature is 38 ℃ and the humidity is 90% RH. The adhesion of the coating to the glassine paper was tested with reference to the national standard GB/T9286-1998. The test results are shown in Table 1.
TABLE 1 product Effect corresponding to the emulsions of examples 1-3 and comparative example 1
| Emulsion and method of making | Oxygen transmission rate (cc/m)2·day) | Water vapor transmission rate (g/m)2·day) | Adhesion force |
| Comparative example 1 | 25 | 48 | 3 |
| Example 1 | 3.0 | 5.3 | 1 |
| Example 2 | 4.2 | 8.4 | 1 |
| Example 3 | 4.8 | 8.9 | 1 |
As can be seen from the test results in Table 1, compared with the conventional PVA emulsion, the modified PVA emulsions of the embodiments 1 to 3 of the present invention can significantly improve the oxygen blocking and water blocking effects of the cellophane, and have a better adhesive force.
The foregoing examples are provided to facilitate an understanding of the principles of the invention and their core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that approximate the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims (10)
1. The modified PVA emulsion is characterized by being prepared from the following raw materials in percentage by mass:
2. the modified PVA emulsion of claim 1, wherein the modifier is selected from one or more of isophorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate.
3. The modified PVA emulsion of claim 1, wherein the catalyst is potassium persulfate and/or sodium persulfate.
4. The modified PVA emulsion of claim 1, wherein the crosslinking agent is glyoxal and/or glutaraldehyde.
5. The modified PVA emulsion of claim 1, wherein the antifoaming agent is ethanol and/or ethylene glycol;
the polymerization degree of the PVA master batch is 500-2000, and the alcoholysis degree is 80-99%;
the water is soft water.
6. A method for preparing a modified PVA emulsion according to any one of claims 1 to 5, comprising the steps of:
a) mixing and heating the PVA master batch and water for dissolving to obtain PVA dissolving liquid;
b) mixing the PVA solution with a catalyst and a cross-linking agent to carry out condensation cross-linking reaction to obtain a cross-linking reaction solution;
c) and mixing the crosslinking reaction liquid with a modifier and a defoaming agent to obtain the modified PVA emulsion.
7. The preparation method according to claim 6, wherein in the step a), the heating and dissolving temperature is 100-110 ℃ and the time is 2-3 h.
8. The preparation method according to claim 6, wherein in the step b), the temperature of the crosslinking reaction is 70-75 ℃ and the time is 0.5-1 h.
9. The composite cellophane is characterized by comprising cellophane and a coating compounded on the surface of the cellophane;
the coating layer is formed by the modified PVA emulsion described in any one of claims 1 to 5 or the modified PVA emulsion prepared by the preparation method described in any one of claims 6 to 8.
10. A method of making a composite glassine paper according to claim 9, comprising:
after the emulsion is coated on the upper surface of the glass, drying to form a coating, and obtaining the composite glass paper;
the modified PVA emulsion according to any one of claims 1 to 5 or the modified PVA emulsion obtained by the method according to any one of claims 6 to 8.
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| CN102277049A (en) * | 2011-08-06 | 2011-12-14 | 海南必凯水性涂料有限公司 | Self-adhesive modified polyvinylalcohol coating and preparation method thereof |
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| CN1389528A (en) * | 2002-06-21 | 2003-01-08 | 华南理工大学 | Water-thinned antistatic paint |
| CN102277049A (en) * | 2011-08-06 | 2011-12-14 | 海南必凯水性涂料有限公司 | Self-adhesive modified polyvinylalcohol coating and preparation method thereof |
| CN103122171A (en) * | 2013-02-05 | 2013-05-29 | 保定宝轶塑料有限公司 | Method for preparing nano polyvinyl alcohol coating liquid by adopting sol-gel method and coating formed by nano polyvinyl alcohol coating liquid |
| CN113150625A (en) * | 2021-05-06 | 2021-07-23 | 海南必凯水性新材料有限公司 | PVOH emulsion for PE coating film and preparation method thereof |
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Application publication date: 20211001 |