Polyvinyl alcohol composition with no blocking and good transparency, film, and preparation method and application thereof

Abstract

The application discloses a polyvinyl alcohol composition with non-blocking and good transparency, a film and a preparation method and application thereof, and mainly solves the problems of poor opening property, poor mechanical property and poor transparency of the film prepared by a polyvinyl alcohol composition in the prior art. The polyvinyl alcohol composition contains the following components in parts by weight: 70-99 parts of polyvinyl alcohol; 5-30 parts of a plasticizer; and 0.01-10 parts of an anti-blocking agent. The anti-blocking agent is selected from at least one of a combination of an organic anti-blocking agent and an inorganic anti-blocking agent, and the mass ratio of the inorganic anti-blocking agent to the organic anti-blocking agent is (1:9)-(9:1), so that the problem is better solved, and the polyvinyl alcohol composition can be used in industrial production of polyvinyl alcohol films.

Description

TECHNICAL FIELD

[0001] The present application discloses a kind of polyvinyl alcohol composition and its preparation method with good film non-blocking and transparency, the feature of the method is that the composition contains the following components by weight: 70-99 parts of polyvinyl alcohol, 10-30 parts of plasticizer, 0.01-10 parts of anti-blocking agent. The components are added into twin-screw extruder at the same time to obtain the polyvinyl alcohol composition. The polyvinyl alcohol composition disclosed in the present application can not only meet the requirements of plasticizing processing, but also the film prepared from the composition has good opening property and transparency, and is easy to use. The preparation method disclosed in the present application is easy to operate and low in cost, which is beneficial to industrialization. The present application widens the application field of polyvinyl alcohol. BACKGROUND

[0002] Polyvinyl alcohol is a kind of water-soluble polymer with excellent oxygen barrier property, oil barrier property, wear resistance and chemical corrosion resistance. The polyvinyl alcohol film prepared therefrom can be widely used in food, medical, washing and textile packaging, and transportation of toxic substances such as pesticides and special substances such as gasoline. At present, the commonly used polyvinyl alcohol film is prepared by solution forming method. Solution processing forming has the disadvantages of complex process, high cost, high energy consumption and low yield. Unlike solution forming, hot plastic processing forming has the advantages of simple process, high efficiency, low cost and low energy consumption. Therefore, hot plastic processing forming has become a research and development hotspot for domestic and foreign enterprises and research institutes. However, polyvinyl alcohol has many hydroxyl groups on the molecular chain, which forms a large number of hydrogen bonds between the molecules, resulting in a very close melting temperature and decomposition temperature, which is difficult to plasticize. Therefore, it is necessary to modify polyvinyl alcohol, reduce the melting temperature and improve the thermal stability to realize hot plastic processing forming of polyvinyl alcohol. At present, the methods for hot plastic processing of polyvinyl alcohol mainly include copolymerization method, blending method, post-reaction method and plasticization method.

[0003] Patent with application publication number CN104109326A discloses an anti-blocking polyvinyl alcohol film and its preparation method. In the patent, the anti-blocking polyvinyl alcohol film includes 5-50 parts by weight of polyvinyl alcohol, 0.05-0.3 parts of nano-zinc oxide, 0.3-7 parts of anti-blocking agent, 0.05-3 parts of surfactant, 0.5-9 parts of plasticizer, 0.01-0.1 parts of defoaming agent and 50-95 parts of deionized water. The preparation method is to mix all the components together uniformly and then to prepare polyvinyl alcohol film by casting. The method is a method for preparing film by aqueous solution, and it is only a small test scheme. When the method is scaled up, a large amount of water needs to be removed, which consumes a lot of energy, and the efficiency of the method is low to match the film preparation process.

[0004] Patents with publication numbers CN105440524A, CN105440522A, and CN105524383A all involve adding functional additives such as stearate, mica, silicon dioxide, or erucic acid amide to improve the opening property of the prepared film, but the formulations use water as a plasticizer and the preparation method uses a single-screw granulator after blending the raw materials, which is different from the composition and preparation method of the present application. Compared with the above, the composition prepared by the method is more uniform, has lower cost, higher efficiency, and better particle processability. SUMMARY

[0005] One of the technical problems to be solved by the present application is the poor opening property and poor transparency of the film prepared from the polyvinyl alcohol composition by the existing thermoplastic method. The present application provides a thermoplastically processable polyvinyl alcohol composition with non-blocking and good transparency. The composition can be thermoplastically processed by the combination of polyvinyl alcohol raw materials and the selection of plasticizer and anti-blocking agent, and the film prepared from the composition has good anti-blocking property and transparency, which can broaden the application field of polyvinyl alcohol resin.

[0006] The second technical problem to be solved by the present application is to provide a preparation method of the polyvinyl alcohol composition corresponding to the first technical problem.

[0007] The third technical problem to be solved by the present application is to provide a polyvinyl alcohol film with non-blocking and good transparency, which uses the polyvinyl alcohol composition for solving the first technical problem.

[0008] The fourth technical problem to be solved by the present application is to provide a preparation method of the polyvinyl alcohol film corresponding to the third technical problem.

[0009] To solve the first technical problem, the technical solution adopted by the present application is as follows: a polyvinyl alcohol composition with non-blocking and good transparency, characterized in that the composition contains the following components in parts by weight:

[0010] a) 70-99 parts of polyvinyl alcohol;

[0011] b) 5-30 parts of plasticizer;

[0012] c) 0.1-10 parts of anti-blocking agent;

[0013] The anti-blocking agent is selected from at least one of the combination of organic anti-blocking agent and inorganic anti-blocking agent, and the mass ratio of the inorganic anti-blocking agent to the organic anti-blocking agent is (1:9) to (9:1).

[0014] In the technical scheme, the anti-adhesion agent contains organic anti-adhesion agent and inorganic anti-adhesion agent, the organic anti-adhesion agent is preferably at least one of amide, stearate, stearate ester and the like, and is more preferably at least one of stearyl amide, behenyl amide, ethylene bis-stearyl amide, ethylene bis-oleic amide, ethylene bis-erucic amide, oleic amide, erucic amide, zinc stearate, calcium stearate, stearic acid monoglyceride, pentaerythritol stearate, silicone powder, sodium dodecyl sulfate and polymethyl methacrylate; the inorganic anti-adhesion agent is preferably at least one of kaolin, mica, calcium hydrogen phosphate, wollastonite powder, diatomite, bentonite, magnesium silicate, talc powder, micron-sized silicon dioxide, nano-sized silicon dioxide, montmorillonite, calcium carbonate, magnesium hydroxide, magnesium sulfate and calcium chloride; the ratio of the inorganic anti-adhesion agent to the organic anti-adhesion agent is 1:9 to 9:1, and is further preferably (1 to 1.5):1, so that the mechanical properties and the transparency of the film can be improved by the mutual cooperation of the two.

[0015] In the technical scheme, the polyvinyl alcohol resin has a polymerization degree of 300 to 3000, and the polyvinyl alcohol has an alcoholysis degree of 70% to 99% in terms of molar fraction. The polyvinyl alcohol is a single component or a mixture of multiple components. The plasticizer is preferably at least one of polyhydric alcohol, polyether polyhydric alcohol or polyhydric alcohol ester. The polyhydric alcohol is preferably one or more than two of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, glycerol ether and the like. The polyether polyhydric alcohol is preferably one or more than two of polyethylene glycol, polypropylene glycol, polyglycerol, ethylene glycol-propylene glycol copolymer, polypropylene oxide and polytetrahydrofuran. The polyhydric alcohol ester is preferably one or more than two of ethylene glycol ester and glycerol ester.

[0016] To solve the second technical problem, the present application adopts the following technical scheme: a preparation method of a polyvinyl alcohol composition, comprising the following steps:

[0017] The polyvinyl alcohol, the plasticizer and the anti-adhesion agent are directly added into a double-screw extruder, and then melted, kneaded and extruded to obtain the polyvinyl alcohol composition.

[0018] In the preparation method, the amount of the polyvinyl alcohol is 70 to 99 parts by weight, the amount of the plasticizer is 5 to 30 parts by weight, and the amount of the anti-adhesion agent is 0.01 to 10 parts by weight. The anti-adhesion agent is at least one selected from the combination of organic anti-adhesion agent and inorganic anti-adhesion agent, and the mass ratio of the inorganic anti-adhesion agent to the organic anti-adhesion agent is (1:9) to (9:1).

[0019] In the technical solution, the anti-adhesion agent contains organic anti-adhesion agent and inorganic anti-adhesion agent. The organic anti-adhesion agent is preferably at least one of amide, stearate, stearate ester, and more preferably at least one of stearyl amide, behenyl amide, ethylene bis-stearyl amide, ethylene bis-oleic amide, ethylene bis-erucic amide, oleic amide, erucic amide, zinc stearate, calcium stearate, stearic acid monoglyceride, pentaerythritol stearate, silicone powder, sodium dodecyl sulfate, and polymethyl methacrylate. The inorganic anti-adhesion agent is preferably at least one of kaolin, mica, calcium hydrogen phosphate, wollastonite powder, diatomite, bentonite, magnesium silicate, talc powder, micron-sized silicon dioxide, nano-sized silicon dioxide, montmorillonite, calcium carbonate, magnesium hydroxide, magnesium sulfate, and calcium chloride. The ratio of the inorganic anti-adhesion agent to the organic anti-adhesion agent is 1:9-9:1, and more preferably (1-1.5):1. The two agents can synergize to improve the mechanical properties and transparency of the film.

[0020] In the technical solution, the polymerization degree of the polyvinyl alcohol resin is preferably 300-3000, and the alcoholysis degree of the polyvinyl alcohol is preferably 70%-99% in terms of molar fraction. The polyvinyl alcohol is a single component or a mixture of multiple components. The plasticizer is preferably at least one of polyhydric alcohol, polyether polyhydric alcohol, or polyhydric alcohol ester. The polyhydric alcohol is preferably one or more than two of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and glycerol ether. The polyether polyhydric alcohol is preferably one or more than two of polyethylene glycol, polypropylene glycol, polyglycerol, ethylene-propylene glycol copolymer, polypropylene oxide, and polytetrahydrofuran. The polyhydric alcohol ester is preferably one or more than two of ethylene glycol ester and glycerol ester.

[0021] The composition is prepared by a one-step thermoplastic processing method. The polyvinyl alcohol, the plasticizer, and the opening agent are directly added to a double-screw extruder, and the thermoplastic polyvinyl alcohol is prepared by melting, kneading, extruding, and granulating. The polyvinyl alcohol composition is further melted and extruded by a single-screw extruder, and the polyvinyl alcohol film is obtained by casting or blowing.

[0022] To solve the third technical problem, the technical solution adopted by the present application is as follows: a polyvinyl alcohol film, which comprises the polyvinyl alcohol composition in any of the technical solutions for solving the first technical problem.

[0023] In the technical solution, the polyvinyl alcohol composition comprises the raw material combination in any of the technical solutions for solving the first technical problem, and the plasticizer and the anti-adhesion agent. The prepared film has good anti-adhesion, mechanical properties, and transparency.

[0024] To solve the above-mentioned technical problems, the technical solution adopted by the present application is as follows: a preparation method of a polyvinyl alcohol film, comprising the following steps:

[0025] The polyvinyl alcohol composition described in any of the technical solutions of the above-mentioned technical problems is melt-extruded by a single-screw extruder, cast or blown into a film to obtain the polyvinyl alcohol film.

[0026] The present application has the advantages that: the raw material of polyvinyl alcohol, the formula conditions of plasticizer and anti-blocking agent are preferred, the polyvinyl alcohol composition prepared by one-step twin-screw processing not only meets the need of thermoplastic processing, but also the film prepared from the composition system has good anti-blocking property, mechanical property and transparency.

[0027] The performance of the present application is determined by the following method.

[0028] Differential scanning calorimetry (DSC) analysis: determined by a Discovery DSC differential scanning calorimeter of American Thermal Analysis Company, under nitrogen atmosphere, gas flow rate 50 mL / min, first heating range 40-220℃, constant temperature for 1 minute, cooling range 220--50℃, constant temperature for 1 minute, second heating range-50-220℃, temperature change rate of the whole process is 10℃ / min. The test results include glass transition temperature (Tg); melting point (Tm); crystallization temperature (Tc) and the like.

[0029] Melt index (MFR) determination: determined by a LLOYD DAVENPORT MFI-10 / 230 melt index instrument according to ASTM D1238 standard, barrel temperature 190℃, weight load 2.16 or 10 kg, die diameter 2 mm, length 8 mm, preheating time 4 min, automatically cut sample every set time, take average value of 5 times, expressed by grams per 10 minutes (g / 10min).

[0030] Haze test: film haze is tested by a BYK-Gardner GmbH instrument.

[0031] The film anti-blocking property test is tested by the method for determining the self-adhesion (shear peeling strength) in 5.6.6 of GB / T10457. Ten pieces of 50 mm long and 25 mm wide samples are cut, two pieces are a group, the adhesive surfaces of the samples are opposite in length direction, the head and tail are overlapped, the overlapping part length is 15 mm and the width is 25 mm, the samples are placed on a smooth plane, a rubber roller is used to roll the samples at a speed of 300 mm / min, and the samples are taken off after 5 times of rolling. L = 100 mm, W = 300 g) is rolled back and forth 3 times at the joint of the sample, so that the joint does not leave air between the two films. The prepared sample is placed in the test environment for 20 minutes, and then tested. The test is performed on a tensile testing machine, and the test equipment meets the requirements of GB / T1040. The tensile speed is 250 ± 50 mm / min. The peeling strength = (the force required for the sample to separate) / (the area of the two films joint), unit: N / cm 2 .

[0032] By adopting the technical scheme of the present application, the polyvinyl alcohol composition obtained is used to prepare a polyvinyl alcohol film, the haze of the film can reach 2, and the tear strength of the film can reach 0.004 N / cm 2 , and good technical effects are achieved.

[0033] The present application will be further described below through embodiments. DETAILED DESCRIPTION

[0034] The present application will be described in detail below.

[0035] The thermoplastic polyvinyl alcohol composition with good opening for use in the present application comprises polyvinyl alcohol, plasticizer and anti-blocking agent. The preparation method of the composition is a one-step method for preparing thermoplastic polyvinyl alcohol.

[0036] In the prior art, in order to prepare thermoplastic polyvinyl alcohol particles, a two-step method is usually adopted: 1) polyvinyl alcohol, plasticizer and various additives are first added to a stirred tank for premixing; 2) then the obtained premixed slurry is added to a single screw extruder for granulation. The composition preparation method disclosed in the present application adopts a one-step method, i.e. polyvinyl alcohol, plasticizer and functional additives are directly added to a twin screw extruder, and thermoplastic polyvinyl alcohol is prepared through melting, kneading, extruding and granulating. Compared with the two-step method, the method has lower processing cost and higher efficiency.

[0037] In the present application, polyvinyl alcohol generally refers to a polymer obtained by polymerization of vinyl ester and alcoholysis. The polyvinyl alcohol in the present application also includes modified polyvinyl alcohol polymers obtained by graft copolymerization of unsaturated carboxylic acid or its derivative, unsaturated sulfonic acid or its derivative, α-olefin with a carbon atom number of 2-30, etc. on the main chain of polyvinyl alcohol, modified polyvinyl alcohol manufactured by saponification of modified polyvinyl ester obtained by copolymerization of vinyl ester and unsaturated carboxylic acid or its derivative, unsaturated sulfonic acid or its derivative, α-olefin with a carbon atom number of 2-30, etc., and so-called polyvinyl acetal resin obtained by crosslinking of a part of hydroxyl groups of unmodified or modified polyvinyl alcohol with aldehydes such as formaldehyde, butyl aldehyde and benzaldehyde, etc.

[0038] The above-mentioned vinyl esters used for producing polyvinyl alcohol can include, for example, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl Versatic acid ester, vinyl laurate, vinyl stearate, vinyl benzoate, and the like.

[0039] The above-mentioned comonomers used for producing polyvinyl alcohol can include, for example, olefins such as ethylene, propylene, 1-butene, isobutylene, and the like; acrylic acid and its salts; acrylic esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, and the like; methacrylic acid and its salts; methacrylic esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, and the like; acrylamide derivatives such as acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N,N-dimethyl acrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts, N-hydroxymethyl acrylamide and its derivatives, and the like; methacrylamide derivatives such as methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts, N-hydroxymethyl methacrylamide and its derivatives, and the like; N-vinyl amide groups such as N-vinyl formamide, N-vinyl acetamide, N-vinyl pyrrolidone, and the like; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, and the like; nitriles such as acrylonitrile, methacrylonitrile, and the like; halogenated vinyls such as chloroethylene, vinylidene chloride, fluoroethylene, vinylidene fluoride, and the like; allyl compounds such as allyl acetate, allyl chloride, and the like; derivatives of unsaturated carboxylic acids such as maleic acid, itaconic acid, and the like, and their salts or esters; vinyl silyl compounds such as vinyltrimethoxysilane, and the like; isopropenyl acetate, and the like. The molar percentage of the comonomer in the polyvinyl alcohol is generally 0-15%.

[0040] The polyvinyl alcohol produced is generally in the form of particles, cylindrical bodies, conical bodies, square bodies, rectangular bodies, sheets, round sheets, S-shaped bodies, V-shaped bodies, hollow cylindrical bodies, hollow conical bodies, hollow square bodies, or hollow rectangular bodies, and the like, and the diameter is generally 0.5-15 mm. The product can be further pulverized. In the present application, the polyvinyl alcohol having a particle size of 0.1-1 mm is preferred in view of the processability of the polyvinyl alcohol.

[0041] The physical properties of polyvinyl alcohol are mainly determined by the polymerization degree and alcoholysis degree of the polymer. The polymerization degree of polyvinyl alcohol is determined according to the method in the national standard GB / T 12010.5-2010. The method is to prepare a sample obtained after complete alcoholysis of polyvinyl alcohol into an aqueous solution, and the average polymerization degree (number average polymerization degree) of polyvinyl alcohol is converted by determining the limiting viscosity of the solution. In the present application, the polymerization degree of polyvinyl alcohol is preferably 300-3000.

[0042] The alcoholysis degree of polyvinyl alcohol is tested according to the method in Appendix D of the national standard GB / T 12010.2-2010. The method is to determine the content of acetic acid re-alcoholized in polyvinyl alcohol to further calculate the alcoholysis degree of polyvinyl alcohol. In the present application, the alcoholysis degree of polyvinyl alcohol is preferably 70%-99%.

[0043] Polyvinyl alcohol has a high content of hydroxyl groups, so the melting temperature and decomposition temperature are close and the melt flowability is poor, and the thermoplastic processing window is narrow. In order to improve the thermoplastic processability, the commonly used methods are chemical modification by copolymerization and physical modification by adding plasticizers. The added plasticizers are inorganic and organic plasticizers. Commonly used organic plasticizers include water, alcohol, ester, amide and anhydride plasticizers. The plasticizer used in the present application is a non-water plasticizer, and the plasticizer used is at least one of a polyol, a polyether polyol or a polyol ester. The polyol is preferably ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, glycerol ether, etc. The polyether polyol is preferably polyethylene glycol, polypropylene glycol, polyglycerol, ethylene glycol-propylene glycol copolymer, polypropylene oxide and polytetrahydrofuran. The polyol ester is preferably ethylene glycol ester and glycerol ester.

[0044] The polyvinyl alcohol particles prepared in the present application have thermoplastic processability, and can be prepared into cast film and blown film products by heating and melting. Such film products can be applied to, but not limited to, detergent packaging, pesticide packaging, laundry bag packaging, transfer printing and the like.

[0045] The present application will be specifically described by the following examples. It should be noted that the examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content, which still belongs to the protection scope of the present application.

[0046]

Example 1

[0047] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%, average particle size 0.6 mm), 25 parts of glycerol, 0.2 parts of bis-ethylene oleic acid amide and 0.3 parts of micron-sized silicon dioxide are simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die are 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed is 250 rpm. The extruded sample is granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules is 24°C, the Tc is 120°C, and the Tm is 176°C. The melt index is 1.8 g / 10 min.

[0048] b) The light yellow thermoplastic polyvinyl alcohol granules obtained in step a) are added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die are 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed is 20 rpm, and the PVA granules are plasticized, melted, extruded, roller-conveyed and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film is 2, and the tear strength of the film is 0.004 N / cm 2 .

[0049]

Example 2

[0050] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%, average particle size 0.6 mm), 25 parts of glycerol, 0.2 parts of bis-ethylene oleic acid amide and 0.3 parts of micron-sized silicon dioxide are simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die are 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed is 250 rpm. The extruded sample is granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules is 24°C, the Tc is 120°C, and the Tm is 176°C. The melt index is 1.8 g / 10 min.

[0051] b) The light yellow thermoplastic polyvinyl alcohol granules obtained in step a) are added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die are 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed is 20 rpm, and the PVA granules are plasticized, melted, extruded, roller-conveyed and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film is 2, and the tear strength of the film is 0.004 N / cm 2 .

[0052]

Example 3

[0053] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%, average particle size 0.6 mm), 25 parts of glycerol, 0.2 parts of sodium dodecyl sulfate and 0.3 parts of micron-sized silicon dioxide are simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the 1st to 9th sections and the die of the extruder are 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed is 250 rpm. The extruded sample is granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules is 24°C, the Tc is 121°C, and the Tm is 176°C. The melt index is 2.2 g / 10 min.

[0054] b) The light yellow thermoplastic polyvinyl alcohol granules obtained in step a) are added into a single-screw extruder, the temperatures of the 1st, 2nd, 3rd sections and the die of the extruder are 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed is 20 rpm, and the PVA granules are plasticized, melted, extruded, roller-conveyed and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film is 2, and the tear strength of the film is 0.004 N / cm 2 .

[0055]

Example 4

[0056] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%, average particle size 0.6 mm), 25 parts of glycerol, 0.2 parts of stearic acid monoglyceride and 0.3 parts of micron-sized silicon dioxide are simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the 1st to 9th sections and the die of the extruder are 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed is 250 rpm. The extruded sample is granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules is 23°C, the Tc is 118°C, and the Tm is 174°C. The melt index is 1.8 g / 10 min.

[0057] b) The light yellow thermoplastic polyvinyl alcohol granules obtained in step a) are added into a single-screw extruder, the temperatures of the 1st, 2nd, 3rd sections and the die of the extruder are 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed is 20 rpm, and the PVA granules are plasticized, melted, extruded, roller-conveyed and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film is 2, and the tear strength of the film is 0.004 N / cm 2 .

[0058]

Example 5

[0059] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%, average particle size 0.6 mm), 25 parts of glycerol, 0.2 parts of diethyleneglycol oleamide and 0.2 parts of kaolin were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules was 25°C, the Tc was 118°C, and the Tm was 173°C. The melt index was 1.9 g / 10 min.

[0060] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film was 3, and the tear strength of the film was 0.005 N / cm 2 .

[0061] Example 6

[0062] a) 84.5 parts of PVA (polymerization degree 500, alcoholysis degree 88%, average particle size 0.6 mm), 15 parts of glycerol, 0.2 parts of sodium dodecyl sulfate and 0.3 parts of micron-sized silicon dioxide were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The Tg of the obtained granules was 27°C, the Tc was 140°C, and the Tm was 181°C. The melt index was 5.0 g / 10 min.

[0063] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The haze of the film was 4, and the tear strength of the film was 0.004 N / cm 2 .

[0064] Comparative Example 1

[0065] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%), 25 parts of glycerol and 0.5 parts of bis-ethylene oleic amide were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The obtained granules had a Tg of 27°C, a Tc of 121°C and a Tm of 178°C. The melt index was 1.9 g / 10 min.

[0066] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The film had a haze of 3 and a tear strength of 0.024 N / cm 2 .

[0067]

Example 1

[0068] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%), 25 parts of glycerol and 0.5 parts of bis-ethylene oleic amide were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The obtained granules had a Tg of 27°C, a Tc of 121°C and a Tm of 178°C. The melt index was 1.9 g / 10 min.

[0069] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The film had a haze of 3 and a tear strength of 0.024 N / cm 2 .

[0070]

Example 1

[0071] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%), 25 parts of glycerol, 0.1 part of diethylene glycol oleamide and 0.4 part of micron silicon dioxide were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The obtained granules had a Tg of 25°C, a Tc of 122°C and a Tm of 179°C. The melt index was 1.6 g / 10 min.

[0072] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The film had a haze of 11 and a tear strength of 0.019 N / cm 2 .

[0073]

Example 4

[0074] a) 74.5 parts of PVA (polymerization degree 1700, alcoholysis degree 88%), 25 parts of glycerol, 0.4 part of diethylene glycol oleamide and 0.1 part of micron silicon dioxide were simultaneously added into a twin-screw extruder at a weight ratio, the temperatures of the extruder 1-9 sections and the die were 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C and 170°C respectively, and the screw rotation speed was 250 rpm. The extruded sample was granulated by a cutting machine after cooling to obtain thermoplastic polyvinyl alcohol granules. The obtained granules had a Tg of 27°C, a Tc of 121°C and a Tm of 178°C. The melt index was 1.6 g / 10 min.

[0075] b) The light yellow thermoplastic polyvinyl alcohol granules prepared in step a) were added into a single-screw extruder, the temperatures of the extruder 1, 2, 3 sections and the die were 190°C, 195°C, 195°C and 195°C respectively, the screw rotation speed was 20 rpm, and the PVA granules were plasticized, melted, extruded, roller transported and drawn to obtain a thermoplastic polyvinyl alcohol casting film by winding. The film had a haze of 9 and a tear strength of 0.031 N / cm 2 .

Claims

1. A polyvinyl alcohol composition comprising, in parts by weight: a) polyvinyl alcohol 70-99; b) plasticizer 15-30; c) anti-blocking agent 0.4-0.5; wherein the anti-blocking agent is selected from at least one of a combination of an organic anti-blocking agent and an inorganic anti-blocking agent, wherein the mass ratio of the inorganic anti-blocking agent to the organic anti-blocking agent is (1-1.5) : 1, the organic anti-blocking agent is at least one of ethylene bis-stearamide, ethylene bis-oleamide, ethylene bis-erucamide, stearic acid monoglyceride, pentaerythritol stearate, sodium lauryl sulfate, the inorganic anti-blocking agent is at least one of kaolin, talc, micronized silica, the polyvinyl alcohol has a degree of polymerization of 300-3000 and a degree of alcoholysis of 70-99% by mole fraction, the plasticizer is at least one of a polyol, a polyether polyol, or a polyol ester, the polyol is one or more than two of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, glycerol ether, the polyether polyol is one or more than two of polyethylene glycol, polyglycerol, polypropylene oxide, and polytetrahydrofuran. The polyol ester is one or more than two of ethylene glycol ester and glycerol ester. The polyvinyl alcohol is a single component or a mixture of multiple components.

4. A method for preparing a polyvinyl alcohol composition, comprising the steps of: directly adding polyvinyl alcohol, plasticizer, and anti-blocking agent into a twin-screw extruder, and obtaining the polyvinyl alcohol composition through melting, kneading, and extruding; wherein the amount of the polyvinyl alcohol is 70-99 parts by weight, the amount of the plasticizer is 15-30 parts by weight, and the amount of the anti-blocking agent is 0.4-0.5 parts by weight, the anti-blocking agent is selected from at least one of a combination of an organic anti-blocking agent and an inorganic anti-blocking agent, the mass ratio of the inorganic anti-blocking agent to the organic anti-blocking agent is (1-1.5) : 1, the organic anti-blocking agent is at least one of ethylene bis-stearamide, ethylene bis-oleamide, ethylene bis-erucamide, stearic acid monoglyceride, pentaerythritol stearate, sodium lauryl sulfate, the inorganic anti-blocking agent is at least one of kaolin, talc, micronized silica, the polyvinyl alcohol has a degree of polymerization of 300-3000 and a degree of alcoholysis of 70-99% by mole fraction, the plasticizer is at least one of a polyol, a polyether polyol, or a polyol ester, the polyol is one or more than two of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, glycerol ether, the polyether polyol is one or more than two of polyethylene glycol, polyglycerol, polypropylene oxide, and polytetrahydrofuran. characterized in that ​ 2. The polyvinyl alcohol composition according to claim 1, characterized by ​ 3. The polyvinyl alcohol composition according to claim 1, characterized by ​ ​ ​ ​ 5. The method of producing a polyvinyl alcohol composition according to claim 4, characterized by The polyhydric alcohol ester is one or more of ethylene glycol ester and glycerin ester; the polyvinyl alcohol is a single component or a mixture of multiple components.

6. A polyvinyl alcohol film comprising the polyvinyl alcohol composition according to any one of claims 1 to 3.

7. A method for preparing a polyvinyl alcohol film, comprising the steps of: melt-extruding the polyvinyl alcohol composition according to any one of claims 1 to 3 through a single-screw extruder, and casting or blowing a film to obtain the polyvinyl alcohol film.

8. Use of the polyvinyl alcohol film according to claim 6 in detergent packaging, pesticide packaging, laundry bag packaging, and transfer printing.