KR101850947B1 - A flexible substrate for blocking water vapor comprising PVA with specific grade and LLDPE, a preparation method thereof and use thereof - Google Patents

Abstract

The present invention relates to a flexible moisture barrier comprising polyvinyl alcohol (PVA) and linear low-density polyethylene (LLDPE) having a degree of saponification of 70-99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less The present invention relates to a method for producing the flexible moisture barrier substrate in the form of a film or a film, and a packaging material coated with the moisture barrier substrate.

Description

TECHNICAL FIELD [0001] The present invention relates to a flexible waterproofing material containing PVA and LLDPE of a specific grade, a process for producing the same,

The present invention relates to a flexible moisture barrier comprising polyvinyl alcohol (PVA) and linear low-density polyethylene (LLDPE) having a degree of saponification of 70-99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less The present invention relates to a method for producing the flexible moisture barrier substrate in the form of a film or a film, and a packaging material coated with the moisture barrier substrate.

Gas barrier films designed to block active gases are one of the most important topics in many applications such as solar cells and electronic devices as well as food packaging. In general, a method of vacuum-depositing aluminum on a polymer film substrate (PET, OPP, CPP, LDPE, etc.) or depositing or coating an inorganic material such as silica or alumina, , Nylon, polyacrylonitrile, polyvinyl chloride (PVDC), and the like are laminated and used. However, the aluminum evaporated film becomes opaque. When an inorganic material is deposited, there is a disadvantage in that a production cost increases due to a high deposition cost, and a gas-barrier polymer film has a problem that it is difficult to form a thin film.

Packing Depending on the characteristics of the product, multi-layer films are generally used as packaging materials because they require functionalities such as moisture barrier, light barrier, and gas barrier. Since electronic products, snacks, processed foods, and cements are susceptible to deformation when exposed to moisture, water-blocking films are usually used for packaging of these products.

 Conventional materials used as packaging materials include polyvinylidene chloride (PVDC), polymer resins such as nylon, aluminum thin film laminates or vapor deposition coating films depending on the products to be packaged. PVDC exhibits excellent moisture barrier properties, As a result, the environmental pollution and the harmfulness of the human body are emerging. Nylon is known to have low moisture barrier properties compared to films of PVDC, aluminum foil laminates or vapor-deposited coatings. In addition, the aluminum thin film laminate or the vapor deposition coating film has a high moisture barrier property, and the manufacturing process is widely used in various companies, but commercialization is difficult due to the relatively high manufacturing cost due to process addition and raw material cost, There is a possibility that cracks and / or pinholes are likely to occur during the deposition process, thereby causing a problem in water shutoff. Accordingly, when the packaging material having no moisture barrier capability is used, the electroconductive material (metal) and other materials used in the display panel in the expensive household appliances may be oxidized to deteriorate the performance or to be impossible to use at all. In order to solve this problem, a method of packaging an electronic product using an existing film packaging material but inserting a silica gel or the like capable of absorbing moisture therein is used, but the effect thereof is insufficient and a low-priced moisture It is necessary to develop barrier film. Although various studies have already been made on moisture barrier films, only a few technologies are commercially available.

Accordingly, the present inventors have made intensive researches to improve water barrier properties by improving general resins such as LLDPE. As a result, they have found that when an absorbent polymer, PVA, is selectively compounded with PVA having a low molecular weight and low degree of saponification, Is dispersed homogeneously and the particles are not exposed to the surface. Therefore, when water is permeated without generating cracks or the like, PVA, which is an absorbing polymer contained in the film, absorbs it and retains it in the film. The amount of water can be remarkably reduced, and the present invention has been completed.

One object of the present invention is to provide polyvinyl alcohol (PVA) and linear low-density polyethylene (LLDPE) having a degree of saponification of 70-99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less To provide a flexible moisture barrier substrate.

Another object of the present invention is to prepare polyvinyl alcohol (PVA) and linear low-density polyethylene (LLDPE) having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less A first step of preparing for pounding; And a second step of extruding the compounding to form a film. The present invention also provides a method for producing a flexible moisture barrier film.

Yet another object of the present invention is to provide a packaging material coated with a flexible moisture barrier material comprising PVA and LLDPE having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less will be.

The present invention relates to a polyvinyl alcohol (PVA) and a linear low density polyethylene (PVA) having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less, low-density polyethylene (LLDPE).

The present invention relates to a PVA having a specific range of molecular weight and degree of saponification and a method of compounding LLDPE to produce a film, which is designed to find a substrate which is flexible and improved in moisture barrier ability by improving a general-purpose resin such as LLDPE using PVA as an absorbent polymer. PVA and LLDPE are highly dispersed and / or miscible, so that particles are not uniformly mixed and exposed to the surface. Therefore, when water is permeated without cracking, PVA, which is an absorbent polymer contained in the film, And the amount of moisture to be permeated can be remarkably reduced because it is absorbed and retained in the film.

For example, PVA may be contained in an amount of 5 to 20% by weight, but is not limited thereto. When the content of PVA is less than 5% by weight, the total amount of moisture that PVA can carry, that is, the maximum moisture adsorption amount of the film is small and the permeability is high, so that the improvement of moisture barrier is less than that of a pure LLDPE film. Only the effect can be shown. On the other hand, when the PVA content exceeds 20% by weight, the amount of moisture absorption of the substrate itself increases, but PVA absorbs moisture and crystallizes, so that compatibility with LLDPE is low.

For example, as an additive for improving the compatibility of Zn-stearate and PVA with LLDPE as a lubricant for allowing material materials to form products well without adhering to equipment when compounded using an extruder Wax, specifically PE-wax, but it is not limited thereto, and additives capable of improving the miscibility between the lubricant and / or the materials can be used without limitation.

In order to improve the miscibility of PVA and LLDPE in the substrate, it is possible to use, for example, maleic acid, dicumyl peroxide, oleic acid, lauryl alcohol, which can act as a surfactant or promote the reaction between PVA and LLDPE upon compounding but is not limited to, one or more compounds selected from the group consisting of alcohol and stearate alcohol.

(PVA) and linear low-density polyethylene (LLDPE) having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less A first step of mixing and preparing compounding; And a second step of extruding the compounding to form a film. The present invention also provides a method for producing a flexible moisture barrier film.

Specifically, the PVA may exhibit a pH in the range of 5 to 7. If the pH is out of this range, the compounding equipment can be overloaded to oxidize or corrode the equipment.

Specifically, the extrusion of the second step may be performed at a temperature of 140 to 200 ° C and a screw speed of 60 to 300 rpm, but is not limited thereto. If the extrusion is carried out at a temperature lower than 140 캜, the PVA and the LLDPE may not be properly mixed so that the PVA and the LLDPE may not be homogeneously mixed or cracks may occur on the contact portion. On the other hand, when the formed film is pyrolyzed at 200 to 250 캜 lower than LLDPE, it may be difficult to decompose and form into a film when extruded at a temperature exceeding 200 캜.

If the screw speed is less than 60, the mass production rate is low. If the screw speed is more than 300 rpm, even dispersion may be difficult, but it is not limited to the performance or other conditions of the apparatus.

For example, the compounding may further comprise Zn-stearate and wax.

For example, the compounding may further comprise at least one compound selected from the group consisting of maleic acid, dicumyl peroxide and oleic acid.

As another embodiment, the present invention provides a packaging material coated with a flexible moisture barrier material comprising PVA and LLDPE having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less as a moisture barrier film to provide.

The flexible moisture barrier material comprising PVA and LLDPE having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less as a moisture barrier film may be used as a coating material directly applied to the surface of the product have.

In addition to foods and medicines, metallic products such as electric / electronic products and automobiles and their parts are susceptible to moisture which is in contact with moisture and which is oxidized, that is, corruption is accelerated or rusted, In order to prolong the storage (or storage) period or the use period of these products, it is preferable to seal them with a packaging material capable of blocking moisture or to introduce a film capable of blocking moisture on the surface.

The moisture barrier material of the present invention can effectively block moisture, and can be used as a packaging material by itself because of its flexibility and predetermined strength, but also can be used as a base layer, a printing layer, an oxygen barrier layer and / A sealing layer for heat sealing, or the like, or may be coated on an existing packaging material.

The water-absorbing polymer PVA and LLDPE compound film having low molecular weight and low degree of saponification of the present invention have high dispersibility and / or miscibility between PVA and LLDPE, so that the particles are not uniformly mixed and exposed to the surface, When the PVA is absorbed and absorbed by the PVA contained in the film, it is possible to reduce the amount of moisture to be permeated because it is contained in the film. It is an excellent moisture barrier material and has a proper strength as well as being flexible. It can be useful for packaging materials of products.

FIG. 1 is a graph showing a mass change with time of a PVA / LLDPE-assisted film according to the PVA grade measured at a constant temperature and humidity condition of 70 ° C. and 90% relative humidity.
Figure 2 is a FE-SEM photograph of LLDPE, 10VL, 10VLM and 10VLMD sheets.
FIG. 3 is a photomicrograph of a PVA / LLDPE preparation film according to LLDPE and PVA grades.
Fig. 4 is a cross-sectional FE-SEM photograph of a PVA / LLDPE preparation film according to the PVA grade.
5 is a diagram showing the result of thermogravimetric analysis of a preparation sheet containing additives to LLDPE and PVA205 / LLDPE.
FIG. 6 is a diagram showing the result of thermogravimetric analysis of a PVA / LLDPE preparation film containing an LLDPE film and various grades of PVA.
7 is a graph showing the tensile strength of a preparation sheet containing additives to LLDPE and PVA205 / LLDPE.
8 is a graph showing the elongation of a preparation sheet containing additives to LLDPE and PVA205 / LLDPE.
9 is a graph showing the tensile strengths of PVA / LLDPE preparation films containing LLDPE films and various grades of PVA.
10 is a graph showing the elongation of an LLDPE film and a PVA / LLDPE preparation film containing various grades of PVA.
11 is a graph showing the oxygen permeability of a PVA / LLDPE preparation film according to the PVA grade.
12 is a graph showing the water permeability of a PVA / LLDPE preparation film according to the PVA grade.
13 is a diagram showing the water content of the PVA / LLDPE-assisted film according to the PVA grade.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

material

PVA (polyvinyl alcohol) was purchased from KURARAY PVA205. The Mowiol products of 4-88, 4-98, 8-88, 18-88, 10-98, and 20-98 used to confirm the effect of PVA molecular weight and degree of saponification were purchased from Sigma-Aldrich Respectively. PAA used Junlon PW-120 product purchased from TOAGOSEI and 3224 product purchased from Hanwha Chemical as general purpose resin LLDPE (linear low-density polyethylene). In the other reagents and samples, MA (maleic acid), DCP (dicumyl peroxide) and OA (oleic acid) are derived from Sigma-Aldrich, Zn-st (Zn-stearate) Were purchased from Yuhan and used.

Example  One: Compounding  Masterbatch through and manufacturing of film from it

A master batch of each sample was prepared by compounding PVA and LLDPE. Specifically, 1.5 kg of LLDPE, 0.18 kg of PVA, 0.02 kg of Zn-st and 0.07 kg of wax were thoroughly mixed using a SHR-10A high-speed mixer (WH-5HR). At this time, the mixture was mixed for 5 to 10 minutes while adjusting the mixing temperature so that the friction temperature of the material did not exceed 45 占 폚. The thoroughly mixed mixture was put into an extruder (Siemens) set in advance to prepare a master batch film. At this time, the temperature of the heater of the extruder was controlled at 140 to 200 ° C and the screw speed was controlled at 60 to 300 rpm to proceed the compound.

In order to confirm the effects according to the PVA grade, films were prepared in the same manner as above using various grades of PVA shown in Table 1 instead of PVA205. All PVA were used in a dry oven at 60 ° C for 24 hours before compounding.

Rating
(grade) Weight average molecular weight
(Mw) Saponification degree
(hydrolysis) Viscosity
(viscosity) pH Polymerization
(polymerization) PVA205 86.5 to 89.0 4.6 to 5.4 5 to 7 500 PVA 4-88 ~ 31,000 86.7 to 88.7 3.5 to 4.5 630 PVA 4-98 ~ 27,000 98.0 to 98.8 4.0 to 5.0 600 PVA 8-88 ~ 67,000 86.7 to 88.7 7.0 to 9.0 1400 PVA 18-88 ~ 130,000 86.7 to 88.7 16.0 to 20.0 2700 PVA 10-98 ~ 61,000 98.0 to 98.8 9.0 to 11.0 1400 PVA 20-98 ~ 125,000 98.0 to 98.8 18.5 to 21.5 2800

The PVA used was selected from PVA having a weight average molecular weight ranging from 20,000 to 150,000 and a degree of saponification ranging from 60 to 100%. The detailed properties of these PVA are shown in Table 1 above.

The content ratio of each component of the sample prepared by varying the mixing ratio of PVA205 and LLDPE and the contents of additives MA, DCP or OA is shown in FIG. The content of MA is based on PVA, the content of DCP on the basis of MA and the content of OA on the basis of LLDPE.

Name of sample PVA content
(weight%) LLDPE content
(weight%) MA
(%) DCP
(%) OA
(%) 10VL 10 90 - - - 10VLM 10 90 5 - - 20VLM 20 80 5 - - 10VLMD 10 90 5 0.03 - 20VLMD 20 80 5 0.03 - 10VLO 10 90 - - 2 20VLO 20 80 - - 2

Experimental Example  1: According to PVA rating Moisture absorption  analysis

In order to confirm the moisture blocking effect according to the PVA grades of the compounding films containing PVA and LLDPE, the change in the degree of hygroscopicity of various grades of PVA having different molecular weights and degree of saponification with time was confirmed, And Table 3 below. As shown in Fig. 1, it was confirmed that the degree of hygroscopicity was high in PVA having a low saponification degree (trade name n-88). In addition, it was confirmed that the compounding film made of PVA having a high molecular weight showed a tendency to have a lower moisture absorption degree when the degrees of saponification were the same.

sample 1 hours 2 hours 3 hours 4 hours 5 hours 6 hours 7 hours PVA205 0.505 0.634 0.713 0.718 0.720 0.722 0.724 PVA 4-88 0.653 0.816 0.876 0.878 0.908 0.910 0.911 PVA 8-88 0.474 0.654 0.701 0.760 0.781 0.788 0.800 PVA 18-88 0.497 0.647 0.708 0.710 0.758 0.763 0.775 PVA 4-98 0.370 0.489 0.504 0.520 0.534 0.544 PVA 10-98 0.329 0.368 0.386 0.412 0.427 0.441 0.448 PVA 20-98 0.324 0.405 0.421 0.428 0.429 0.431 0.435

Experimental Example  2: morphology analysis

The shapes of the sheets and films of the samples prepared according to Example 1 were observed using a Field Emission Scanning Electron Microscope (FE-SEM, JSM-6701f, JEOL).

FE-SEM images of pure LLDPE sheets and compound sheets comprising MA, DCP, OA or combinations thereof as PVA and LLDPE and / or additives in the composition shown in Table 2 above were observed and found to be between PVA and LLDPE , And the results are shown in Fig.

In addition, the PVA and LLDPE compounding films prepared using the pure LLDPE film and the various grades of PVA shown in Table 1 were visually observed and photographed, and the results are shown in FIG. As shown in FIG. 3, pure LLDPE, 10VL (PVA205), 4-88 and 4-98 compound films, when observed with naked eyes, were transparent and clean on the surface, but were 90% or less such as 8-88 or 18-88 And PVA having a high molecular weight, it was confirmed that PVA particles were not mixed with LLDPE and still existed as independent particles because particles that were large enough to be visually recognized were observed on the surface .

Further, in order to confirm the difference in the dispersibility between PVA and LLDPE due to the difference in molecular weight and degree of saponification, cross sections of PVA and LLDPE compounding films prepared using various grades of PVA having different molecular weights and degrees of saponification were measured by FE-SEM , And the results are shown in Fig. As shown in Fig. 4, in the case of a film containing 18-88, which is a PVA having a high molecular weight, it was confirmed that the PVA was embedded in a large mass on the LLDPE substrate. This means that as the molecular weight of the PVA used increases, that is, as the PVA particles become larger, the dispersion is not easy and the PVA particles are not miscible with the LLDPE and are maintained in individual particle form to such an extent that they can be visually confirmed. On the other hand, PVA205, 4-88 and 4-98 having small molecular weights could be appropriately mixed in the LLDPE film since they have remarkably improved dispersibility compared with PVA having the above molecular weight. At this time, when 4-88 and 4-98 are compared with each other, it can be seen that 4-88 having lower degree of saponification has better dispersibility than 4-98.

As a result, the PVA and LLDPE compounding films have better dispersibility as the molecular weight of the PVA contained therein is lower and the saponification degree is lower, so that they can be mixed well without being separated from each other. Therefore, PVA is uniformly distributed in the LLDPE, It is possible to provide a defect-free film even on the contacted portion.

Experimental Example 3: Thermogravimetric analysis

The composition of the compound was analyzed and thermogravimetry analysis (TGA-50, Shimadzu) was performed while increasing the temperature from room temperature to 600 ° C at a rate of 10 ° C / min.

A thermogravimetric analysis was carried out on the samples further containing additives such as PVA, LLDPE compounding sample and crosslinking initiator prepared according to Example 1 to determine the pyrolysis temperature and the indirect reaction.

First, the compound was made into a sheet and TGA was measured. The results are shown in FIG. As shown in FIG. 5, the pyrolysis temperature of each sample was around 200 to 250 DEG C lower than that of pure LLDPE at 400 DEG C. On the other hand, VLMD, which further contains MA and DCP as a crosslinking initiator, can be inferred to have a reaction between PVA and LLDPE as compared with the conventional VL sample because the curvature of the curve is gentle on the TGA graph.

Further, thermogravimetric analysis was performed on the compounding films prepared using various grades of PVA, and the results are shown in Fig. As shown in FIG. 6, it was confirmed that each sample had similar slope curves at around 10% as shown in FIG. 6, and the thermal decomposition temperatures of the tested PVA and LLDPE compound films were 200 to 250 The temperature of the extruder was controlled so as not to exceed 200 DEG C when these compounds were molded into a film.

Experimental Example  4: Analysis of mechanical properties

Tensile strength and elongation were measured using universal testing machine (UTM) to analyze the mechanical properties. Each sample was measured three times and averaged.

The mechanical properties of a compound sheet containing PVA205 or various grades of PVA and LLDPE and a compound sheet containing MA, DCP OA or a combination thereof were measured, and the results are shown in Table 4 below. In the case of a sample to which DCP as a crosslinking initiator was added, the reactivity was high and the strength was too high. However, this indicates that addition of a crosslinking initiator can significantly improve strength when compounded. The tensile strengths measured on these compound sheets are shown in Fig. 7, and the elongation ratios are shown in Fig. As shown in FIGS. 7 and 8, the presence of additive particles whose reaction was not fully advanced resulted in lower tensile strength and elongation of the compound sheets compared to the pure LLDPE sheet. However, in the case of tensile strength, addition of MA or OA exhibited an excellent tensile strength close to that of a pure LLDPE sheet, which was less than that of a sample not containing these additives. From this it can be seen that when compounding PVA and LLDPE, the properties of the sheet and / or film produced therefrom can be controlled by imparting the reaction and / or the dispersibility between PVA and LLDPE by means of additives such as MA, DCP or OA Respectively.

Name of sample Tensile strength (kg / mm ² ) Elongation (%) LLDPE 1.245 5588.82 20VL 0.758 382.74 10VLM 1.048 1696.28 20VLM 1.029 900.39 10VLO 1.084 3260.00 20VLO 0.956 776.86

Also, tensile strength and elongation were measured for PVA and LLDPE compound films prepared using various grades of PVA, and the results are shown in Figs. 9 and 10 and Table 5 below.

Name of sample Tensile strength (kg / mm ² ) Elongation (%) LLDPE 1.245 623.84 10VLM 0.992 429.07 10VL 1.188 670.38 4-88 0.975 294.52 4-98 1.005 449.63 8-88 0.802 389.30 18-88 0.907 383.80 10-98 0.844 433.27 20-98 0.825 130.17

7 and 9 showing the tensile strengths show that 10 VLM, 10 VL (PVA 205), 4-88 and 4-98 films (or sheets) have the most similar level of tensile strength compared to pure LLDPE sheet (or film) 10VL was the closest value.

Next, when comparing the elongation ratios, 10VL showed the best elongation when pure LLDPE sheet (or film) and 10VL, 4-88 and 4-98 films with almost no visible particles on the surface were compared. On the other hand, in the case of some other samples, since holes are formed due to large particles present on the surface, it is difficult to produce a film by using a blowing machine. Therefore, when measuring the physical properties using UTM, To 10 times higher than that of the other samples.

Experimental Example 5: Permeation Analysis

To analyze the gas permeability, oxygen transmission rate (O 2) was measured at 0% relative humidity using Oxygen permeation analyzer (OX-TRAN model 702, Mocon) and carrier gas (98% OTR) was measured using a water vapor transmission rate test system (WVTR Transmission Rate Test System, PERMATRAN W-700, Mocon) and nitrogen as a carrier gas at a temperature of 37.8 ° C and a relative humidity of 100% ) Were measured.

Oxygen permeability of compounding films of various grades of PVA and LLDPE was measured. At this time, in the case of a sample in which the PVA particles are visually confirmed on the film surface, the measurement itself exceeded the maximum measurement reference value due to the occurrence of pinholes. Therefore, from the morphological analysis of Experimental Example 2, the oxygen permeability over time was measured for 10VL and 4-88 films confirmed to have the smoothest surface, and the results are shown in FIG. As shown in FIG. 11, the 4-88 film exhibited significantly lower oxygen permeability than the 10VL film, indicating that the 4-88 film had better oxygen barrier capacity than the 10VL film.

Also, the water permeabilities of 10 VL, 4-88 and 4-98 films having the smoothest surface were measured, and the results are shown in FIG. As shown in FIG. 12, the water permeability is kept low for a certain period of time, and rapidly increases at any moment. This means that the amount of moisture absorbed by the PVA, which is a hygroscopic polymer existing in the PVA and LLDPE compound film, , It is inferred that the amount of moisture to be permeated increases sharply as PVA absorbs sufficient moisture and starts to form a gap with LLDPE.

Experimental Example  6: Moisture content analysis

Moisture content was measured at 105 ° C using a water content meter (MA100H, Sartorius).

The water contents of PVA and LLDPE compound films containing various grades of PVA were measured, and the results are shown in FIG. 13 and Table 6 below. As shown in Fig. 13, 10 VL and 8-88 films showed the highest values. This shows that there is a similar pattern to the result of the hygroscopicity analysis in Experimental Example 1 described above. Thus, although the 8-88 film shows the highest moisture content, as shown in the morphology analysis, the surface is rugged due to the presence of PVA particles, which is somewhat disadvantageous for use as a film.

Name of sample Moisture content (%) 10VL 1.285 4-88 0.894 4-98 1.123 8-88 1.303 18-88 1.036

Comprehensively, PVA and LLDPE compound films 10VL, 4-88 and 4-98 prepared using PVA with relatively low molecular weight and degree of saponification showed high moisture absorption and water content And thus can be usefully used as a moisture barrier substrate.

Claims (9)

A first step of drying polyvinyl alcohol (PVA) having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less;
The dried PVA is adjusted to 5 to 20% by weight based on the total amount of PVA and LLDPE so that the PVA absorbs water and is not crystallized during the compounding mixing, and is mixed with linear low-density polyethylene (LLDPE) A second step of preparing the second step; And
And a third step of extruding the compounding and molding it into a film.
Wherein the PVA and the LLDPE are uniformly mixed.
The method according to claim 1,
Wherein the PVA has a degree of saponification of 86.7 to 88.7%, a weight average molecular weight in the range of 30,000 to 32,000, and a degree of polymerization of 650 or less.
The method according to claim 1,
Wherein the compounding further comprises zinc-stearate (Zn-stearate) and wax.
The method according to claim 1,
Wherein the compounding further comprises at least one compound selected from the group consisting of maleic acid, dicumyl peroxide and oleic acid.
The method according to claim 1,
Wherein said PVA exhibits a pH in the range of 5 to 7. < Desc / Clms Page number 20 >
The method according to claim 1,
Wherein the extrusion of the third step is carried out at a temperature of from 140 to 200 DEG C and a screw speed of from 60 to 300 rpm.
The method according to claim 1,
Wherein the PVA has a viscosity of 3.5 to 4.5 mPa · s.
The method according to claim 1,
Wherein the PVA has a degree of saponification of 86.7 to 88.7%, a weight average molecular weight of 31,000, a viscosity of 3.5 to 4.5 mPa · s, and a degree of polymerization of 650.
A dry polyvinyl alcohol (PVA) produced according to any one of claims 1 to 8 and having a degree of saponification of 70 to 99%, a weight average molecular weight of 70,000 or less and a degree of polymerization of 650 or less, A flexible moisture barrier film that is uniformly mixed with linear low-density polyethylene (LLDPE) in the absence of moisture and not crystallized.

Images