CN113088020B - Easily-torn thermoplastic polyvinyl alcohol film and preparation method and application thereof - Google Patents

Easily-torn thermoplastic polyvinyl alcohol film and preparation method and application thereof Download PDF

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CN113088020B
CN113088020B CN202010025265.2A CN202010025265A CN113088020B CN 113088020 B CN113088020 B CN 113088020B CN 202010025265 A CN202010025265 A CN 202010025265A CN 113088020 B CN113088020 B CN 113088020B
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polyvinyl alcohol
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alcohol film
thermoplastic polyvinyl
temperature
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CN113088020A (en
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王洪学
胡圳
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/16—Cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0017—Combinations of extrusion moulding with other shaping operations combined with blow-moulding or thermoforming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/92—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/9258—Velocity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92704—Temperature
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2329/00—Characterised by the use of 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; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
    • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
    • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Thermal Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Medicinal Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

Abstract

The invention provides an easily-torn thermoplastic polyvinyl alcohol film and a preparation method and application thereof. The film is prepared by thermoplastic molding of polyvinyl alcohol by a thermoplastic agent and longitudinal stretching molding. The film has the characteristic of anisotropy, the Hermans orientation factor is greater than 0.5, the tensile strength ratio of the longitudinal stretching direction to the transverse stretching direction is greater than 8, the tear strength ratio of the transverse stretching direction to the longitudinal stretching direction is greater than 3.5, the optical performance of the film is excellent, and the film can be used in the fields of adhesive tapes and the like.

Description

Easily-torn thermoplastic polyvinyl alcohol film and preparation method and application thereof
Technical Field
The invention belongs to the field of processing and preparation of high polymer materials, and relates to an easily-torn thermoplastic polyvinyl alcohol film, and a preparation method and application thereof.
Technical Field
The adhesive tape is one of products commonly used in life, the typical structure is three layers, namely a release coating, a base material and an adhesive, polypropylene (PP) is used as a main raw material of the base material, a PP film subjected to biaxial stretching has good water vapor barrier property, is not degraded or dissolved in water, is easy to cause environmental pollution and other problems when used in large quantities, and is not easy to tear and has no anisotropy. In the process of manufacturing the adhesive tape, if the film has excellent easy-tearing performance and anisotropy, the production and the actual use are more facilitated.
Polyvinyl alcohol is a general functional polymer material obtained by saponification and alcoholysis of polyvinyl acetate generated by vinyl acetate polymerization, and a film prepared from the polyvinyl alcohol has the characteristics of environmental friendliness, degradability, water solubility, barrier property, heat sealing property and the like.
At present, the methods for preparing polyvinyl alcohol film mainly include solution method, such as the methods used in CN 105440521A, CN 105440522A, CN 105440523A and CN 105440524A series of patents, and thermoplastic processing method, and the former has high production cost and low efficiency, so the use of the latter process to prepare polyvinyl alcohol film is receiving more and more attention. However, the thermoplastic polyvinyl alcohol film prepared by the existing thermoplastic process has problems in preparation stability and performance stability of the film, and the film prepared by the traditional film blowing and casting processes is not easy to tear and has no anisotropy.
In the prior patents CN 106189006A and CN 109721905A, the strength of the stretched film is improved by biaxial stretching molding of the thermoplastic polyvinyl alcohol, and the application field of the thermoplastic polyvinyl alcohol is expanded, but the tearing performance of the film after biaxial stretching is poor. The practicability in the field of low and middle end films such as adhesive tapes is low.
Disclosure of Invention
One of the technical problems to be solved by the invention is to provide an easily-torn thermoplastic polyvinyl alcohol film, which has the anisotropic characteristic, the Hermans orientation factor is more than 0.5, the tensile strength ratio of the longitudinal stretching direction to the transverse stretching direction is more than 8, the tearing strength ratio of the transverse stretching direction to the longitudinal stretching direction is more than 3.5, and the optical performance is excellent.
The second technical problem to be solved by the invention is to provide a preparation method of the easily-torn thermoplastic polyvinyl alcohol film corresponding to the first technical problem.
The third technical problem to be solved by the invention is to provide an application method of the easily-torn thermoplastic polyvinyl alcohol film corresponding to one of the technical problems.
In order to solve one of the above technical problems, the technical scheme adopted by the invention is as follows: an easily tearable thermoplastic polyvinyl alcohol film comprises polyvinyl alcohol and a thermoplastic agent; the film is characterized in that the Hermans orientation factor of the film is greater than 0.5, the tensile strength ratio of the longitudinal stretching direction to the transverse stretching direction is greater than 8, and the tear strength ratio of the transverse stretching direction to the longitudinal stretching direction is greater than 3.5.
In the technical scheme, the mass ratio of the polyvinyl alcohol to the thermoplastic agent is preferably (70-95) to (5-30).
In the above technical solution, the polyvinyl alcohol is preferably selected from one or more of a mixture having a polymerization degree of 400 to 3000 and an alcoholysis degree of 80 to 99mol%.
In the above technical solution, the thermoplastic agent preferably contains at least one of polyol, polyether polyol or polyol alcoholate; further preferably: the polyalcohol is preferably one or more of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, xylitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and monoglyceryl ether; the polyether polyol is preferably one or more than two of polyethylene glycol, polypropylene glycol, polyglycerol, ethylene glycol-propylene glycol copolymer, polypropylene oxide and polytetrahydrofuran; the polyol ester compound is preferably one or more than two of glycol ester and glyceride compounds.
In the above technical solution, a more preferable solution is: the thermoplastic agent contains at least one of ethylene glycol, glycerol, pentaerythritol, sorbitol, mannitol and xylitol, and at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol.
In the above technical solution, the most preferable solution is: the thermoplastic agent contains at least two of ethylene glycol, glycerol, pentaerythritol, sorbitol, mannitol and xylitol and at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol; for example, the thermoplastic agent contains glycerol, 1, one of pentaerythritol, mannitol and xylitol, 2, and one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol, 3; more preferably, the mass ratio of the three components is 1.
In the technical scheme, the thermoplastic polyvinyl alcohol film is preferably obtained by thermoplastic molding of polyvinyl alcohol and a thermoplastic agent and longitudinal stretching molding; further preferably: the longitudinal stretching process comprises the following steps: a preheating section, a stretching section, an annealing section, a cooling section and a winding section; the temperature of the preheating section is 150-190 ℃, preferably 160-180 ℃; the temperature of the stretching section is 140-180 ℃, preferably 150-170 ℃; the temperature of the annealing section is 100-140 ℃, preferably 110-130 ℃; the roller temperature of the cooling section is 20-40 ℃; the stretch ratio of the stretch section is preferably 3 to 6.
In order to solve the second technical problem, the invention adopts the technical scheme that: a method for preparing a tearable thermoplastic polyvinyl alcohol film according to any one of the above solutions to solve the above problems, comprising the steps of:
1) Adding polyvinyl alcohol and a thermoplastic agent with required amount into a double-screw extruder, and obtaining the thermoplastic polyvinyl alcohol through melting, kneading and extruding;
2) And melting and extruding the required amount of the thermoplastic polyvinyl alcohol by a single-screw extruder, and then stretching and forming longitudinally to obtain the easily-torn thermoplastic polyvinyl alcohol film.
In the above technical scheme, the preparation method of the thermoplastic polyvinyl alcohol is a twin-screw continuous melt blending extrusion method, preferably, the dried polyvinyl alcohol and the thermoplastic agent are blended according to a required proportion and then added into a twin-screw extruder for melting, kneading, extruding and granulating to obtain the thermoplastic polyvinyl alcohol; more preferably: and directly adding the dried polyvinyl alcohol and the thermoplastic agent into a double-screw extruder according to a required proportion for melting, kneading, extruding and granulating to obtain the thermoplastic polyvinyl alcohol.
In the technical scheme, the double-screw extrusion temperature of the preparation method is 140-240 ℃, preferably 180-220 ℃; the screw speed is 50 to 500rpm, preferably 150 to 300rpm.
In the above technical solution, in the preparation method of the thermoplastic polyvinyl alcohol film, the thermoplastic polyvinyl alcohol is preferably melt-extruded by a single-screw extruder and then guided out through a casting die or a blowing die to obtain a thermoplastic polyvinyl alcohol sheet, the average thickness is preferably 90 to 120 μm, and more preferably 105 μm, and then the sheet is longitudinally stretched and molded to obtain the easily tearable thermoplastic polyvinyl alcohol film.
In the technical scheme, the melting temperature of the single screw is 140-240 ℃, preferably 180-220 ℃; the mold temperature is 150 to 250 ℃, preferably 190 to 230 ℃.
In the technical scheme, the longitudinal stretching molding is to stretch the obtained thermoplastic polyvinyl alcohol sheet to a device; the longitudinal stretching process is divided into five stages: a preheating section (consisting of at least 5 metal rollers), a stretching section (consisting of at least 2 metal rollers), an annealing section (consisting of at least 2 metal rollers), a cooling section (consisting of at least 1 metal roller) and a winding section; the temperature of each roller of the preheating section is preferably 150-190 ℃, more preferably 160-180 ℃, and further preferably the temperature of each roller is the same; the temperature of each roller of the stretching section is preferably 140-180 ℃, more preferably 150-170 ℃, and further preferably the temperature of each roller is the same; the temperature of each roller of the annealing section is preferably 100-140 ℃, more preferably 110-130 ℃, and further preferably the temperature of each roller is the same; the roller temperature of the cooling section is preferably 20-40 ℃, and the roller temperature is further preferably the same; the draw ratio (in the ratio of fast to slow rolls) of the draw section is preferably 3 to 6.
In order to solve the third technical problem, the technical scheme adopted by the invention is as follows: a method for applying the tearable thermoplastic polyvinyl alcohol film according to any of the above technical solutions to solve the technical problems.
In the above technical solutions, the application method is not particularly limited, and can be used in various application fields known in the art, for example, but not limited to, the application method is applied in the fields of adhesive tapes and the like.
The materials and preparation methods used in the present invention are briefly described below:
1. thermoplastic polyvinyl alcohol
The degree of polymerization of polyvinyl alcohol suitable for preparing the thermoplastic polyvinyl alcohol of the invention is 400-3000, and the degree of alcoholysis is 80-99 mol%.
The thermoplastic polyvinyl alcohol is high melt strength and high fluidity polyvinyl alcohol obtained by performing thermal plasticizing modification on polyvinyl alcohol to improve the processing difficulty and poor melt fluidity of the polyvinyl alcohol caused by intramolecular and intermolecular forces, the processing temperature window is widened, and the thermoplastic processing performance is obviously improved. The thermoplastic polyvinyl alcohol is prepared by blending 70-95% of polyvinyl alcohol (in mass fraction) and 5-30% of thermoplastic agent (in mass fraction) in proportion and then introducing or directly introducing the polyvinyl alcohol for melt blending and extrusion by adopting a double-screw melt blending and extrusion processing technology. The thermoplastic agent contains at least one of polyol, polyether polyol or polyol esterified compound; further preferably: the polyalcohol is preferably one or more of ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol, xylitol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and monoglyceryl ether; the polyether polyol is preferably one or more than two of polyethylene glycol, polypropylene glycol, polyglycerol, ethylene glycol-propylene glycol copolymer, polypropylene oxide and polytetrahydrofuran; the polyol ester compound is preferably one or more of glycol ester and glyceride compound; more preferably, the scheme is as follows: the thermoplastic agent contains at least one of ethylene glycol, glycerol, pentaerythritol, sorbitol, mannitol and xylitol, and at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol; the most preferable scheme is as follows: the thermoplastic agent contains at least two of ethylene glycol, glycerol, pentaerythritol, sorbitol, mannitol and xylitol and at least one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol; for example, the thermoplastic agent contains glycerol 1, pentaerythritol 2, mannitol 2, and diethylene glycol 3, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and tetrapropylene glycol; more preferably, the mass ratio of the above three components is 1.
2. Easily-torn thermoplastic polyvinyl alcohol film
Anisotropic in the present invention means a property of polyvinyl alcohol exhibiting a large difference between the longitudinal stretching direction and the transverse stretching direction in some properties such as tensile strength, tear strength, etc. Thermoplastic polyvinyl alcohol films cast or blown thermoplastically are not easy to tear, cannot be applied to the fields such as adhesive tapes which have higher anisotropy requirements on the films, and have lower tensile strength.
The easily-torn thermoplastic polyvinyl alcohol film is obtained by thermoplastic molding of polyvinyl alcohol by a thermoplastic agent and longitudinal stretching molding. The film has the characteristic of anisotropy, the Hermans orientation factor is larger than 0.5, the tensile strength ratio of the longitudinal stretching direction to the transverse stretching direction is larger than 8, the tear strength ratio of the transverse stretching direction to the longitudinal stretching direction is larger than 3.5, and the optical performance is excellent. The longitudinal stretching process can enable polyvinyl alcohol molecular chains to move along the longitudinal stretching direction, but the influence on the transverse stretching direction is small, so that the film has orientation, and the thermoplastic polyvinyl alcohol film is easy to tear along the longitudinal stretching direction.
3. Method for preparing easily-torn thermoplastic polyvinyl alcohol film
The preparation method of the invention is a three-step film forming method. In the method for preparing the thermoplastic polyvinyl alcohol, a polyvinyl alcohol raw material and a thermoplastic agent are respectively metered according to a certain feeding proportion and simultaneously added into a double-screw extruder for granulation; in the preparation method of the thermoplastic polyvinyl alcohol film, the thermoplastic polyvinyl alcohol is melted and extruded into a sheet by a single-screw extruder, and the sheet is longitudinally stretched and molded to obtain the thermoplastic polyvinyl alcohol film.
The twin-screw melt extrusion temperature suitable for the present invention is 140 to 240 ℃, preferably 180 to 220 ℃; the rotating speed of the screw is 50-500 rpm, preferably 150-300 rpm; the single screw melt extrusion temperature is 140-240 ℃, preferably 180-220 ℃; the temperature of the die is 150-250 ℃, preferably 190-230 ℃; the longitudinal stretching process is divided into five stages: a preheating section (consisting of 5 metal rollers), a stretching section (consisting of 2 metal rollers), an annealing section (consisting of 2 metal rollers), a cooling section (consisting of 1 metal roller) and a winding section; the temperature of each roller of the preheating section is the same and is 150-190 ℃, and preferably 160-180 ℃; the temperature of each roller of the stretching section is the same and is 140-180 ℃, preferably 150-170 ℃; the temperature of each roller of the annealing section is the same and is 100-140 ℃, and preferably 110-130 ℃; the roller temperature of the cooling section is 20-40 ℃; the draw ratio (ratio of fast to slow rolls) of the draw section is 3-6.
Continuous twin-screw extrusion apparatus suitable for use in the present invention include twin-screw extruders of different designs, such as the ZSK Mcc18 co-rotating parallel twin-screw extruder manufactured by Coperion, germany, and the like.
The longitudinal stretching apparatus suitable for the present invention includes various models designed by various companies, such as LCR-300 longitudinal stretching apparatus manufactured by LabTech of Thailand, and the like.
The invention discloses an easily-torn thermoplastic polyvinyl alcohol film prepared by a method of longitudinal stretching after double-screw continuous melt extrusion. One embodiment of the invention is that under the same test condition, the easily-torn thermoplastic polyvinyl alcohol film obtained by adopting the technical scheme of the invention has the characteristic of anisotropy, the Hermans orientation factor is more than 0.5, the tensile strength ratio of the longitudinal stretching direction to the transverse stretching direction is more than 8, the tearing strength ratio of the transverse stretching direction to the longitudinal stretching direction is more than 3.5, and the optical performance is excellent, so that the easily-torn thermoplastic polyvinyl alcohol film has a wide application range and obtains a better technical effect.
The invention performs the performance and structure determination according to the following method:
thickness test of the film: the test was carried out using a portable spiral thickness gauge manufactured by German Mahr measuring instruments Ltd, five discrete positions of the middle part of the film were selected for the test, and the average value was taken.
Differential Scanning Calorimetry (DSC) testing of films: the tests were performed on a Discovery series Differential Scanning Calorimeter (DSC) manufactured by TA Instruments, inc., with the processing software TA Instruments Trios version 3.1.5, equipped with a Refrigerated cooking System 90 mechanical refrigeration accessory. The testing atmosphere is 50mL/min of nitrogen, and the quantity of the film sample required by the test is 5-10 mg. The test procedure was as follows: the temperature is stabilized at 20 ℃ and then raised to 220 ℃ at a speed of 10 ℃/min. The temperature rise was recorded to study the thermal properties of the samples. By DSC measurements, the melting temperature ("T") of the sample can be directly derived from the software m "), enthalpy change (". DELTA.H "), etc.
X-ray diffraction (XRD) testing of the films: measured by a Bruker D8 type X-ray diffractometer of Bruker company of Germany, a Cu/Ka micro-focusing light source and the radiation wavelength is
Figure BDA0002360294260000061
Tube voltage is 50kV, tube current is 1000 muA, area detector VANTEC, transmission mode, exposure time is 3min. Through XRD test, hermans orientation factor and crystallinity information of the film sample can be obtained.
Tensile break strength test of the film: the test was carried out according to ISO 527-3 using a model 3344 materials tester from Instron with the processing software Bluehill version 2.31. Type 5 specimens in ISO 527-3 standard were cut out in the longitudinal and transverse directions of the film and placed in a Bluepard BPS-100CB constant temperature and humidity cabinet (temperature 23 ℃ C., relative humidity 50%) of Shanghai-Hengsciences instruments Ltd for 24 hours. During the test, the initial fixture spacing was 75mm, the test tensile rate was 100mm/min, and each sample was tested at least 5 times, and the average value was taken.
Tear strength testing of the films: the tear resistance test is carried out by adopting a Labthink SLY-S1 type tear resistance tester according to the GB/T16578.2-2009 standard. The film was cut into a rectangular shape in the standard in the longitudinal stretching direction and the transverse stretching direction, and left in a Bluepard BPS-100CB constant temperature and humidity cabinet (temperature 23 ℃ C., relative humidity 50%) of Shanghai-Hengjun scientific instruments Co., ltd. For 24 hours. The test was carried out using a pendulum whose energy absorbed during tearing was between 20% and 80% of the total energy of the pendulum, and the same sample was averaged 5 times.
Detailed Description
The present invention is specifically described by the following examples. It should be noted that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention, and that those skilled in the art can make modifications and adaptations of the present invention.
[ COMPARATIVE EXAMPLE 1 ]
The polymerization degree of the used polyvinyl alcohol is about 1200, the alcoholysis degree is about 95 percent,using PolyLab HAAKE from Thermo Fisher science and technology, USA TM The Rheomex OS PTW16 co-rotating twin-screw extruder (screw diameter 16mm, L/D = 40) was subjected to thermoplastic extrusion, pelletization. The extruder has a total of 11 sections from a feeding port to a die, and the number of the sections is 1-11, wherein the section 1 only plays a role of feeding and cannot be heated. And a powder feeder attached to the extruder is used for feeding the polyvinyl alcohol raw material into the twin-screw after calibration, and the feeding speed is 820g/hr. No hydrothermal plasticizer (a mixture of 86% glycerol, 7% xylitol, and 7% tripropylene glycol by mass) was fed into the extruder through the feed port at a feed rate of 180g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 180 ℃,190 ℃,200 ℃,200 ℃,200 ℃,200 ℃,200 ℃,200 ℃,200 ℃,190 ℃ and the screw speed is set at 250rpm. The extruder was equipped with a circular die having a diameter of 3mm, and the specimens were air-cooled and cut into thermoplastic polyvinyl alcohol (TPVA) particles having a diameter of about 3mm by a cutter. Collecting particles, and packaging for later use.
The TPVA particles are HAAKE manufactured by Thermo Fisher scientific Co., U.S.A TM Films were prepared by extrusion casting on a Rheomex OS single screw extruder with a screw diameter of 19mm and a length to diameter ratio of 25 equipped with a 3 TM OS torque rheometer platform control. The extruder has three heating sections, the temperature from the feed inlet to the outlet is 190 ℃,200 ℃ and 200 ℃, TPVA melt is extruded through a flat die, is drawn by a series of rollers at the front end, is cooled and is wound, and the average thickness of a single-layer TPVA film is 43 mu m.
[ COMPARATIVE EXAMPLE 2 ]
TPVA particles (comparative example 1) HAAKE mentioned hereinabove TM Sheets were prepared by extrusion casting on a Rheomex OS single screw extruder. The extruder has three heating sections, the temperature from the feed inlet to the outlet is 190 ℃,200 ℃ and 200 ℃, TPVA melt is extruded through a flat die, is drawn by a series of rollers at the front end, is cooled and is rolled, and the average thickness of the TPVA slice is 375 mu m.
The above sheets were biaxially stretched on a Karo IV biaxial stretching tester, manufactured by Brukner, germany. The equipment is provided with three module sections, only the front two sections are used, the first section is a preheating and stretching section, the preheating temperature is 195 ℃, the longitudinal stretching magnification is 3 times, and the transverse stretching magnification is 3 times; the second section is an annealing and shaping section, and the annealing temperature is 120 ℃. The single-layer TPVA film obtained by biaxial stretching had an average thickness of 43 μm.
[ COMPARATIVE EXAMPLE 3 ]
According to the method described in comparative example 1, except that the thermoplastic agent was 95% xylitol, 5% tripropylene glycol by mass, TPVA particles were obtained.
HAAKE prepared by subjecting the above-mentioned particles to the above-mentioned treatment TM Sheets were prepared by extrusion casting on a Rheomex OS single screw extruder. The extruder has three heating sections, the temperature from the feed inlet to the outlet is 190 ℃,200 ℃ and 200 ℃, TPVA melt is extruded through a flat die, is drawn by a series of rollers at the front end, is cooled and is rolled, and the average thickness of the TPVA slice is 105 mu m.
The above sheet was stretched on an LCR-300 type longitudinal stretching apparatus manufactured by Thailand Lab Tech. The stretching process is divided into five stages: the temperature of each roller of the preheating section is 165 ℃; the temperature of each roller of the stretching section is 160 ℃; the temperature of each roller of the annealing section is 120 ℃; the temperature of each roller of the cooling section is 30 ℃; the draw ratio (ratio of fast to slow rolls) of the draw section was 4. The average thickness of the single-layer TPVA film obtained by longitudinal stretching was 43 μm.
[ example 1 ]
TPVA particles (comparative example 1) HAAKE mentioned hereinabove TM Sheets were prepared by extrusion casting on a Rheomex OS single screw extruder. The extruder has three heating sections, the temperature from the feed inlet to the outlet is 190 ℃,200 ℃ and 200 ℃, TPVA melt is extruded through a flat die, is drawn by a series of rollers at the front end, is cooled and is wound, and the average thickness of a single-layer TPVA sheet is 105 mu m.
The above sheet was stretched on a longitudinal stretching apparatus of LCR-300 type manufactured by the Thailand Lab Tech company. The stretching process is divided into five stages: the temperature of each roller of the preheating section is 165 ℃; the temperature of each roller of the stretching section is 160 ℃; the temperature of each roller of the annealing section is 120 ℃; the temperature of each roller of the cooling section is 30 ℃; the draw ratio (ratio of fast to slow rolls) of the draw section was 3. The average thickness of the single-layer TPVA film obtained by longitudinal stretching was 63 μm.
[ example 2 ]
The process of example 1 except that the draw ratio of the draw section is 4. The single-layer TPVA film obtained by longitudinal stretch forming had an average thickness of 43 μm.
[ example 3 ] A method for producing a polycarbonate
The process of example 1 except that the draw ratio of the draw section is 5. The average thickness of the single-layer TPVA film obtained by MDO forming is 33 μm.
[ example 4 ] A method for producing a polycarbonate
The process of example 1 except that the draw ratio of the draw section is 6. The single-layer TPVA film obtained by longitudinal stretch forming has the average thickness of 23 μm.
[ example 5 ]
The results of Differential Scanning Calorimetry (DSC) tests performed on 5 films including comparative example 1 and examples 1 to 4 are shown in table 1, as described above.
TABLE 1 DSC results T of each film sample m,H And Δ H m,H
Figure BDA0002360294260000101
From Table 1, the melting temperature (T) of the single layer TPVA film of the present invention (example 2) m,H ) And change in fusion enthalpy (. DELTA.H) m,H ) Respectively increased by 5.6 ℃ and 11.1 J.g compared with the film of comparative example 1 -1 And increases with increasing draw ratio (examples 1 to 4). The molecular chain of the film possibly moves, and the structural regularity is increased, so that the T of the film is effectively improved m,H And Δ H m,H 。
[ example 6 ]
X-ray diffraction (XRD) tests were performed on 7 films including comparative examples 1 to 3 and examples 1 to 4 as described above, and the influence of longitudinal stretch forming on the crystallinity and orientation factor of the single-layer TPVA film was mainly examined, and the results are shown in table 2.
TABLE 2 XRD results crystallinity and Hermans orientation factor for each film sample
Figure BDA0002360294260000102
The Hermans orientation factor represents the orientation of the molecular chain axis direction relative to a reference direction, 0 represents no orientation, and 1 represents ideal orientation. As can be seen from table 2, the crystallinity and Hermans orientation factor of the single layer TPVA film of the present invention (example 2) were improved by 18.3% and 0.76 as compared to the film of comparative example 1, and increased with increasing draw ratio (examples 1 to 4). In addition, thermoplastic processing with a xylitol and tripropylene glycol binary thermoplastic (comparative example 3) produced films with less crystallinity than the ternary thermoplastic (example 2), probably due to different plasticizing processes of the different thermoplastics.
[ example 7 ] A method for producing a polycarbonate
The tensile break strength test was performed on 7 films including comparative examples 1 to 3 and examples 1 to 4 as described above, and the difference in tensile strength between different TPVA films was mainly examined, and the results are shown in table 3.
TABLE 3 tensile Strength at Break in different directions for each film sample
Figure BDA0002360294260000111
As can be seen from table 3, the TPVA films of the present invention (examples 1 to 4) had a greatly improved tensile strength in the machine direction, which was 8.4 times as large as that of comparative example 1 (example 4), and a smaller increase in tensile strength in the transverse direction. In contrast to comparative examples 1 and 2, in which the ratio of the tensile strength in the machine direction to that in the transverse direction was greater than 8 and the film had anisotropy, the ratios of the tensile strengths in the machine direction and the transverse direction were 1.5 and 1.0, respectively, and the film had no anisotropy. It can also be seen from Table 3 that the film containing xylitol and tripropylene glycol bipolymer (comparative example 3) has a significantly smaller increase in tensile strength than the film containing the tripartite thermoplastic (example 2), probably due to the different thermoplasticizing effects caused by the different compositions of the thermoplastic.
[ example 8 ]
The results of the film tear strength tests conducted on 6 films including comparative examples 1 and 2 and examples 1 to 4 were shown in table 4, with the differences in tear strength being examined mainly for the different TPVA films.
TABLE 4 tear Strength in different directions for each film sample
Figure BDA0002360294260000121
As can be seen from Table 4, the TPVA films of the present invention (examples 1 to 4) had a significantly lower tear strength in the machine direction than comparative example 1, and had easy tearability, while the tear strength in the transverse direction was significantly increased. The ratio of tear strength in the transverse direction to that in the longitudinal direction was greater than 3.5 and up to 8.4 (example 4), and the film had excellent anisotropy. In addition, the TPVA films of comparative example 1 and comparative example 2 had a tear strength ratio of 1.1 in both the transverse direction stretching and the longitudinal direction stretching directions, and had no anisotropy.

Claims (26)

1. An easily-torn thermoplastic polyvinyl alcohol film comprises polyvinyl alcohol and a thermoplastic agent; the thermoplastic agent is characterized by comprising glycerol A, xylitol B, one of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol and tripropylene glycol C; the mass ratio of the A to the B to the C is (70 to 95) = (15 to 2.5): (15 to 2.5) = (B to C); the polyvinyl alcohol is selected from one or a mixture of more of which the polymerization degree is 400-3000 and the alcoholysis degree is 80-99 mol%; the mass ratio of the polyvinyl alcohol to the thermoplastic agent is (70 to 95) to (5 to 30); the thermoplastic polyvinyl alcohol film is obtained by performing thermoplastic molding on polyvinyl alcohol and a thermoplastic agent and performing longitudinal stretching molding; the film has a Hermans orientation factor greater than 0.5, a tensile strength ratio of a machine direction stretch direction to a transverse direction stretch direction greater than 8, and a tear strength ratio of the transverse direction stretch direction to the machine direction stretch direction greater than 3.5.
2. The tearable thermoplastic polyvinyl alcohol film according to claim 1, wherein the longitudinal stretch forming comprises: a preheating section, a stretching section, an annealing section, a cooling section and a winding section; the temperature of the preheating section is 150-190 ℃; the temperature of the stretching section is 140-180 ℃; the temperature of the annealing section is 100-140 ℃; the roller temperature of the cooling section is 20-40 ℃; the stretch ratio of the stretch section is 3 to 6.
3. The tearable thermoplastic polyvinyl alcohol film according to claim 2, wherein,
the temperature of the preheating section is 160-180 ℃.
4. The tearable thermoplastic polyvinyl alcohol film according to claim 2, wherein,
the temperature of the stretching section is 150-170 ℃.
5. The tearable thermoplastic polyvinyl alcohol film of claim 2, wherein,
the temperature of the annealing section is 110-130 ℃.
6. A preparation method of the easily torn thermoplastic polyvinyl alcohol film as claimed in any one of claims 1 to 5, which comprises the following steps:
1) Adding polyvinyl alcohol and a thermoplastic agent with required amount into a double-screw extruder, and obtaining the thermoplastic polyvinyl alcohol through melting, kneading and extruding;
2) And melting and extruding the required amount of the thermoplastic polyvinyl alcohol by a single-screw extruder, and then stretching and forming longitudinally to obtain the easily-torn thermoplastic polyvinyl alcohol film.
7. The preparation method of the easily torn thermoplastic polyvinyl alcohol film as claimed in claim 6, wherein the extrusion temperature of the twin-screw extruder is 140-240 ℃; the rotating speed of the screw is 50-500 rpm; the single-screw extruder comprises a step of guiding out through a casting die or a film blowing die in a melt extrusion mode to obtain the thermoplastic polyvinyl alcohol sheet.
8. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 7,
the extrusion temperature of the double-screw extruder is 180-220 ℃.
9. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 7,
the screw rotating speed of the double-screw extruder is 150-300 rpm.
10. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 7,
the average thickness of the sheet is 90 to 120 μm.
11. The method of claim 10, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the average thickness of the flakes was 105 μm.
12. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 7,
the melt extrusion temperature of the single-screw extruder is 140-240 ℃.
13. The method of claim 12, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the melt extrusion temperature of the single-screw extruder is 180-220 ℃.
14. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 7,
the temperature of the casting mould or the film blowing mould is 150-250 ℃.
15. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 14,
the temperature of the casting mould or the film blowing mould is 190-230 ℃.
16. The method for preparing the easily tearable thermoplastic polyvinyl alcohol film according to claim 6, wherein the longitudinal stretching is performed; the longitudinal stretching process is divided into five stages: a preheating section, a stretching section, an annealing section, a cooling section and a winding section.
17. The method for preparing a tearable thermoplastic polyvinyl alcohol film according to claim 16,
the preheating section consists of at least 5 metal rollers, the stretching section consists of at least 2 metal rollers, the annealing section consists of at least 2 metal rollers, and the cooling section consists of at least 1 metal roller.
18. The method of claim 17, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the preheating section is 150-190 ℃.
19. The method of claim 18, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the preheating section is 160-180 ℃.
20. The method of claim 17, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the stretching section is 140-180 ℃.
21. The method of claim 20, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the stretching section is 150-170 ℃.
22. The method of claim 17, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the annealing section is 100-140 ℃.
23. The method of claim 22, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the temperature of each roller of the annealing section is 110-130 ℃.
24. The method of claim 17, wherein the step of forming the easily tearable thermoplastic polyvinyl alcohol film,
the roller temperature of the cooling section is 20-40 ℃.
25. The method of claim 16, wherein the tearing of the thermoplastic polyvinyl alcohol film is facilitated by the presence of a solvent,
the stretch ratio of the stretch section is 3 to 6.
26. An application of the tearable thermoplastic polyvinyl alcohol film of any one of claims 1 to 5 in the field of adhesive tapes.
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EP1881044A2 (en) * 2006-07-21 2008-01-23 Tesa AG Mono-axially stretched polypropylene film with a high tear resistance in the cross direction
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