JPH0139684B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention is directed to a biaxially oriented polypropylene film that has heat sealing properties, gas barrier performance, and anti-blocking properties, has a good appearance, and has extremely excellent transparency. This relates to a manufacturing method. ``Prior art'' Biaxially oriented polypropylene resin film, which is often used as a packaging film, has transparency, rigidity,
Although it has excellent properties such as water vapor barrier properties, it has difficulties in gas barrier properties, heat sealing properties, etc. Therefore, by forming a synthetic resin layer made of polyvinylidene chloride resin, etc., which has excellent properties such as gas barrier properties and heat sealability, on the biaxially stretched polypropylene resin film, it is possible to improve the gas barrier properties. It is designed to improve heat sealability, etc., and is coated with synthetic resin latex whose main component is polyvinylidene chloride resin.
A method is used in which the polyvinylidene chloride resin layer is formed by drying. ``Problems to be Solved by the Invention'' By the way, a biaxially oriented polypropylene resin film having a coating resin layer obtained by coating and drying the latex containing polyvinylidene chloride resin as a main component has the following advantages: Small irregularities (such as ``orange peel'' or ``golf ball'') that do not affect the haze of the film
) is generated on its surface, which not only deteriorates the appearance of the film, but also
This is also a factor that reduces the transparency of the resulting film. In the production of a biaxially oriented polypropylene resin film having the coating resin layer, the anti-blocking performance during rolling and ripening after coating of the synthetic resin latex, the slipping properties of the resulting biaxially oriented polypropylene film, etc. In order to improve the performance, a latex coating liquid is usually used in which fine inorganic powder is added, but the fine inorganic powder in the latex coating liquid further deteriorates the transparency of the resulting film. It also has The small irregularities on the surface of the coating resin layer, which are referred to as "orange peel" or "golf ball" mentioned above, can be solved by forming the coating resin layer using a coating liquid made of the synthetic resin latex liquid mentioned above. It is thought that it is produced when the latex particles partially aggregate during the drying process during the formation of the coating resin layer as drying progresses. It is also considered to be one indicator of the transparency of a film having a coating resin layer. In addition, the decrease in transparency of the film that occurs when a latex coating solution containing fine inorganic powder is used is caused by drying after coating a latex coating solution containing fine inorganic powder on a ready-made film. It is thought that this is because, during the process, the resin emulsion particles in the coating liquid aggregate around the inorganic fine powder, whose particle size is one or more orders of magnitude larger than the particles. Due to the above-mentioned causes, although the degree of severity varies depending on the presence or absence of inorganic fine powder in the coating resin layer, in films with a coating resin layer obtained using a resin latex coating liquid, ,
Deterioration in appearance and reduction in transparency were considered to be unavoidable phenomena. In contrast, the method of the present invention obtains a biaxially oriented polypropylene film with gas barrier properties and heat-sealing properties by coating and drying a resin latex coating solution, but with a good appearance. To provide a method for producing a biaxially oriented polypropylene film which has extremely excellent transparency and also has excellent blocking resistance during rolling and ripening after coating with a resin latex coating solution. It is something. "Means for Solving the Problems" The method for producing a biaxially oriented polypropylene film having a coating resin layer of the present invention provides a method for producing a biaxially oriented polypropylene film having a transparent
A resin latex coating solution is applied to at least one of the front and back sides of an axially oriented polypropylene resin film, and dried to obtain a biaxially oriented polypropylene resin film in which at least one side is covered with a coating resin layer. The resin latex coating liquid includes a polyvinylidene chloride resin latex, and 0.3 to 10 parts by weight of polyvinyl alcohol based on 100 parts by weight of the polyvinylidene chloride resin in the polyvinylidene chloride resin latex.
A latex containing at least one water-soluble polymer selected from carboxymethyl cellulose or hydroxyethyl cellulose, and 0.02 to 1.0 parts by weight of inorganic fine powder per 100 parts by weight of the resin component in the latex coating liquid. A coating liquid is used. In the method for producing a biaxially oriented polypropylene film having a coated resin layer of the present invention having the above structure, the biaxially oriented polypropylene resin film on which the coated resin layer is formed is composed of polypropylene, a propylene-α.olefin copolymer, and further is obtained by biaxially stretching a raw sheet obtained from a film-forming raw material containing the above-mentioned polypropylene or propylene-α.olefin copolymer as a main component in a conventional manner, mechanical strength, transparency,
It exhibits extremely excellent effects in terms of rigidity, etc. In addition, when applying the latex coating liquid for forming the coating resin layer to the biaxially stretched polypropylene resin film, if necessary, apply the following steps in advance.
The surface of the biaxially oriented polypropylene resin film is subjected to adhesion improving treatment, such as flame treatment, corona discharge treatment, anchor coating treatment with polyethyleneimine resin, isocyanate resin, etc. It is. The anchor coating treatment for improving adhesion is carried out using, for example, a roll coater, a gravure coater, a rod coater, an air knife coater, a spray coater, or the like. A latex coating liquid applied to the biaxially oriented polypropylene resin film, that is,
a polyvinylidene chloride resin latex, and at least 0.3 to 10 parts by weight of polyvinyl alcohol, carboxymethyl cellulose, or hydroxyethyl cellulose based on 100 parts by weight of the polyvinylidene chloride resin in the polyvinylidene chloride resin latex. A latex coating solution containing one or more water-soluble polymers and 0.02 to 1.0 parts by weight of inorganic fine powder per 100 parts by weight of the resin component in the coating solution is a polyvinylidene chloride resin latex. By adding and mixing a fixed amount of water-soluble polymer, that is, at least one kind of water-soluble polymer selected from polyvinyl alcohol, carboxymethyl cellulose, or hydroxyethyl cellulose, and a predetermined amount of inorganic fine powder. It is easily obtained. The amount of the water-soluble polymer relative to the polyvinylidene chloride resin in the latex coating solution may be determined as appropriate depending on the concentration of the polyvinylidene chloride resin in the coating solution, the type of water-soluble polymer used, etc. However, if the amount of the water-soluble polymer added is less than 0.3 parts by weight based on 100 parts by weight of the polyvinylidene chloride resin in the latex coating solution, the addition of the water-soluble polymer The effect produced by
In other words, the good appearance and excellent transparency of the resulting coating resin layer are likely to be insufficiently maintained, and if the amount exceeds 10 parts by weight based on 100 parts by weight of the polyvinylidene chloride resin in the latex coating solution. This not only reduces the transparency (transparency expressed by haze) of the biaxially oriented polypropylene film having the coating resin layer, but also reduces the heat sealability and gas There is a tendency for the original functions such as barrier properties and anti-blocking properties to deteriorate, and since the latex coating liquid itself has a high viscosity, the stability of the coating liquid over time is poor, and there are various coating methods. Due to restrictions, etc., the amount of water-soluble polymer relative to the polyvinylidene chloride resin in the latex coating liquid is used within the range of 0.3 to 10 parts by weight per 100 parts by weight of the polyvinylidene chloride resin. It is necessary to do so. The water-soluble polymer used is at least one selected from polyvinyl alcohol, carboxymethyl cellulose, and hydroxyethyl cellulose, and polyvinyl alcohol is referred to as a so-called water-soluble polymer. Various polyvinyl alcohols can be used with respect to saponification degree, polymerization degree, etc., and even modified polyvinyl alcohols in which various monomers are graft-polymerized may be used. Furthermore, carboxymethyl cellulose and hydroxyethyl cellulose may be used as long as they are water-soluble, and various types of etherification degree, polymerization degree, etc. can be used. The inorganic fine powder in the latex coating liquid imparts anti-blocking properties to the resulting coated resin layer, and examples thereof include silica powder, fine silicic acid, and talc. In addition, when the amount of inorganic fine powder in the latex coating liquid is less than 0.02 parts by weight based on 100 parts by weight of the resin component in the latex coating liquid, blocking effected by the addition of the inorganic fine powder The prevention performance is insufficient, and if the amount exceeds 1.0 parts by weight, the transparency of the resulting coating resin layer will decrease, making it impossible to obtain a biaxially stretched polypropylene film with excellent transparency properties. Because it will disappear,
The inorganic fine powder needs to be used in an amount of 0.02 parts by weight to 1.0 parts by weight based on 100 parts by weight of the resin component in the latex coating liquid. Further, the application of the latex coating liquid when forming the coating resin layer is carried out using, for example, a roll coater, a gravure coater, a rod coater, an air knife coater, a spray coater, or the like. "Example" The specific structure of the method for producing a biaxially stretched polypropylene film having a coating resin layer of the present invention will be described below based on Examples. Examples 1 to 5 Tolylene diisocyanate [trade name: Coronate] was applied to the corona discharge treated surface of a 20μ thick biaxially stretched polypropylene film whose one surface had been subjected to corona discharge treatment (wetting tension of the treated surface: 40 dyne). An anchor coating layer is formed by applying an anchor coating agent prepared by diluting a polyurethane adhesive made by Nippon Polyurethane Industries Co., Ltd. with ethyl acetate at a resin content of approximately 0.3 g/m ² and drying. was formed. Immediately thereafter, each coating liquid listed in each column of Examples 1 to 5 in Table 1 below is applied to the surface of the anchor coat layer in the coating amount listed in each column, After drying, the film was aged at 40° C. for 20 hours to obtain a biaxially stretched polypropylene film having a coating resin layer on one surface. The coating solution is prepared by putting the inorganic fine powder into a homomixer and then adding warm water at 40 to 60°C.
A dispersion liquid with a concentration of 1% is prepared, and this dispersion liquid is cooled to room temperature, and a water-soluble polymer is mixed in water, which is heated and dissolved to make a 5% aqueous solution, and this is cooled to room temperature. It was obtained by stirring and mixing a water-soluble polymer solution that had been cooled to a temperature of 100 mL into a polyvinylidene chloride resin latex. After that, on the other one side surface of the biaxially stretched polypropylene film having the coating resin layer on one side obtained above, the same procedure as the above-mentioned method for forming the coating resin layer is repeated. Five types of biaxially stretched polypropylene films having the same coating resin layer on both upper and lower surfaces were obtained. Various physical properties of the obtained biaxially stretched polypropylene film having the coated resin layer are shown in Table 2. In each of the above Examples, the production of a biaxially oriented polypropylene resin film having a coating resin layer on both the upper and lower surfaces was explained, but the biaxially oriented polypropylene resin film having a coating resin layer of the present invention In the film manufacturing method, a biaxially oriented polypropylene resin film is prepared by
It is sufficient that the coating resin layer is formed on at least one of the lower surfaces. Comparative Examples 1 to 3 Coating liquids made of resin latexes having the compositions listed in the respective columns of Comparative Examples 1 to 3 in Table 1 below were coated with coating liquids made of resin latexes having the compositions listed in the respective columns of Comparative Examples 1 to 3. A coating resin layer was provided on both the upper and lower surfaces by the same procedure as in Examples 1 to 5 above, except that the coating amount was
Various types of biaxially oriented polypropylene resin films were obtained. Obtained 2 with a coating resin layer for comparison
Various physical properties of the axially stretched polypropylene resin film are shown in Table 2. The weight of the polyvinylidene chloride resin latex in the coating liquid in Table 1 is the weight of the polyvinylidene chloride resin component in the latex, and the amount of coating liquid is the weight of the polyvinylidene chloride resin latex in the coating liquid. This is the amount of resin component applied. Further, each component listed in Table 1 is as follows. Polyvinylidene chloride resin latex Product name: Deiophan 2076-D Yuka Verdecie Co., Ltd. Inorganic fine powder Inorganic silica with an average particle size of 2 μm Product name: Cyroid #150 Fuji Davison Chemical Co., Ltd. Inorganic silica with an average particle size of 4 μm Product name : Thyroid #72 Fuji Davison Chemical Co., Ltd. Water-soluble resin Polyvinyl alcohol (A) Product name: Poval 105 Kuraray Co., Ltd. Polyvinyl alcohol (B) Product name: Poval 117 Kuraray Co., Ltd. Carboxymethyl cellulose Product name: Celogen 7A Daiichi Kogyo Seiyaku Co., Ltd. In addition, the physical property values of the biaxially stretched polypropylene resin film having the coating resin layer shown in Table 2 were measured according to the following method. Haze (%) Haze meter "ND-" manufactured by Nippon Denshoku Industries Co., Ltd.
Values measured using ``H20D''. Transparency (%) CLARITY manufactured by Murakami Color Technology Institute
Average value of local maximum value T _MAX and local minimum value T _MIN measured using METER "TM-1D". Moisture permeability (g/m ² /24hrs) Values measured using an infrared automatic moisture permeability measurement device "Mo-CON IRC-2C" manufactured by Modern Control in the United States. Friction coefficient Value of static friction coefficient obtained in accordance with ASTM D-189412 using Tensilon "UTM-4L" manufactured by Toyo Seiki Co., Ltd. Minimum heat-sealable temperature (°C) Using a thermal gradient tester manufactured by Toyo Seiki Co., Ltd., the strength of the sealed portion heat-sealed at various temperatures under a pressure of 2 kg/cm ² was tested by Toyo Seiki Co., Ltd. Measured at a tensile speed of 300mm/min using Tensilon "UTM-4L", the obtained strength was 100g/min.
Minimum temperature of 25mm or more.

【table】

[Table] "Operations and Effects of the Invention" The method for producing a biaxially stretched polypropylene film having a coating resin layer of the present invention has a transparent biaxially stretched polypropylene film.
At least one surface of the axially oriented polypropylene resin film is coated with a polyvinylidene chloride resin latex and 0.3 to 10 parts by weight of polyvinyl alcohol and carboxylic acid per 100 parts by weight of the polyvinylidene chloride resin in the polyvinylidene chloride resin latex. At least one water-soluble polymer selected from methylcellulose or hydroxyethylcellulose and a resin component in the coating liquid.
It consists of applying and drying a latex coating liquid containing 0.02 to 1.0 parts by weight of inorganic fine powder per 100 parts by weight. Therefore, in the method for producing a biaxially oriented polypropylene film having a coated resin layer of the present invention having the above-mentioned structure, the polyvinylidene chloride resin that is the main component of the solid component in the coating liquid is used in the resulting coated resin layer. The water-soluble polymer imparts gas barrier properties and heat-sealing properties to the coating resin, and the water-soluble polymer serves to improve the appearance of the resulting coating resin layer and maintain its transparency. Furthermore, the inorganic fine powder in the coating liquid provides anti-blocking properties to the formed coating resin layer. Therefore, in the method for producing a biaxially oriented polypropylene film having a coating resin layer according to the present invention, in addition to heat sealing properties and gas barrier properties, it also has excellent transparency, that is, in particular, it has excellent transparency. In the case of a coating resin layer formed by coating and drying a coating liquid using a synthetic resin latex containing powder, there is no significant decrease in transparency, which was previously thought to be unavoidable. A biaxially oriented polypropylene film having a good appearance and excellent anti-blocking properties can be obtained.

Claims (1)

[Claims] 1 A polyvinylidene chloride resin latex is applied to at least one surface of a transparent biaxially oriented polypropylene resin film, and 0.3 to 10 parts by weight of the polyvinylidene chloride resin latex is applied to 100 parts by weight of the polyvinylidene chloride resin in the polyvinylidene chloride resin latex. polyvinyl alcohol, carboxymethylcellulose,
or at least one water-soluble polymer selected from hydroxyethyl cellulose;
0.02 to 1.0 per 100 parts by weight of resin component in coating liquid
1. A method for producing a biaxially oriented polypropylene film having a coating resin layer, which comprises applying and drying a latex coating solution containing part by weight of an inorganic fine powder.