JP2006089652A - Polypropylene sheet, packaging vessel made of the polypropylene sheet and formed product of the polypropylene sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve slipperiness without reducing transparency in relation to an independent sheet cut board and a roll sheet irrespective of a single layer or multiple layers in a polypropylene sheet and its formed products. <P>SOLUTION: The polypropylene sheet is prepared by forming a coating film of a synthetic resin, a wax, a surfactant, an inorganic/organic fine powder, an antistatic agent and the like in 0.001-5μm thickness on at least one side of the substantially noncrystalline and nonoriented polypropylene sheet and making 1-2,000 surface protrusions/mm<SP>2</SP>having 0.1-5μm height at least on the other surface. In addition, at least either one of irregularities of various crepe patterns such as wavy, scaly, pear skin, leather crepe patterns and the like is made on the surface in combination with the surface protrusions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene sheet excellent in transparency, slipping property, antistatic property, antiblocking property, printing ink adhesion to a sheet, adhesion between sheets, a packaging container and a sheet molded product using the same.

  Polypropylene is a polymer called general-purpose plastic as well as polyethylene, etc. It is relatively inexpensive and lightweight, and can be easily molded with a high melting point, so it can be used for automobile parts, home appliances, food packaging films, toys, miscellaneous goods, etc. Widely used in

  Polypropylene sheets include single layer sheets and two or three layer laminated sheets. In the laminated sheet, at least one surface layer is polypropylene (hereinafter referred to as PP in the present specification unless otherwise specified). And preferably, the surface of the sheet is roughened by corona discharge treatment on at least one surface in order to roughen the surface layer of the PP sheet, add an appropriate polar group, and make the coating coating agent easily adhere to the PP sheet. The wetting index is about 38 to 52 dyn / cm. The wetting index is determined by applying a series of mixed liquids with different surface tensions in order as specified in JIS K 6768 to the surface of polyethylene or polypropylene film, and just wetting the film. It is a numerical value of the surface tension (dyn / cm) {N / cm} of the prepared mixed liquid.

  By the way, in the PP sheet, in particular, in the packaging field etc., in order to make the contents look more beautiful, what has high permeability is required, wound around a plurality of rolls, and heated by a heating roll unit, There has been proposed a method in which a thermoplastic resin sheet is caused to travel in close contact, and after the surface pressure contact, the thermoplastic resin sheet is peeled off from the endless belt (see, for example, Patent Document 1).

  However, with PP sheets, when using UV offset printing, automatic punching, and automatic gluing (using hot melt or primer treatment and instantaneous adhesive), PP sheet compounding (kneading) is used for clear cases. Aging or the like is performed so that a certain antistatic agent or slip agent bleeds out (bleeds out) on the sheet surface and the antistatic property or slip property is improved.

For example, after PP sheet production, after aging (curing) for 2 to 3 days at 40 to 50 ° C., it is sufficient for practical use for the first time by performing natural aging for 2 to 3 weeks and performing additional aging. Antistatic property and slip property can be obtained. Further, in order to further improve the slip property, powder such as corn starch powder is mist-like and sprayed on both the front and back surfaces of the sheet. Although it is performed separately from the antistatic agent, the slip agent, and the embossing of the surface, etc., it is considered that the improvement of the slip property by these may be insufficient.
Japanese Unexamined Patent Publication No. 6-26529

  However, considering the actual situation of PP sheet transactions, the above-described aging process is not possible. That is, at present, sales of sheets called special size sizes are common, and it is necessary to cut out from PP sheets manufactured in standard sizes (cell plate: 670 × 1460 mm, L size: 800 × 1100 mm). is there. If such a sales form is adopted, the deterioration of the yield due to the difference in size is unavoidable (currently it is said that the yield is 80%, etc.), and a solution is also desired from a management viewpoint.

  In addition, because of powder such as corn starch powder that is spread to improve the slipping property, when printing on the surface by, for example, UV offset printing, the printing machine is stopped once for 1500 to 2500 sheets, and the printing machine The hassle of having to clean the blanket cylinders. Since the speed of a general printing machine is 5000 to 8000 revolutions / hour, in that case, the printing machine is stopped once every 15 to 30 minutes as described above, and the adhered powder on the blanket cylinder is removed. . In addition, air is removed before printing to remove powder, and in multicolor printing, the first two colors are used to remove powder and printing is performed twice. In any case, there is a problem that the blanket cylinder must be powdered.

  Accordingly, an object of the present invention is to make it possible to improve the antistatic property and the slip property, which have an immediate effect and durability, without requiring or almost unnecessary aging in the production of a polypropylene sheet.

  In addition, the present invention eliminates or almost eliminates the need for powder for improving the slip property, and eliminates or almost eliminates the need for kneading of an antistatic agent or slip agent, and necessitates cleaning of the blanket cylinder of the printing press. An object of the present invention is to provide a PP sheet having excellent properties that can be eliminated or reduced and used for offset printing.

The polypropylene sheet according to claim 1 of the present invention has a coating film made of synthetic resin, wax, surfactant, inorganic / organic fine powder or the like having a thickness of 0.001 to 5 μm on at least one surface, and at least 1 to 2,000 / mm ² of surface protrusions having a height of 0.1 to 5 μm are provided on the other surface.

  According to the second aspect, a coating film of synthetic resin, wax surfactant or the like is formed on at least one surface with a thickness of 0.001 to 5 μm, and at least the other surface is corrugated, scale-like, satin-like. It is characterized in that it is provided with at least one of irregularities of various texture patterns such as skin texture.

According to the third aspect of the present invention, a coating film of synthetic resin, wax, surfactant, inorganic / organic fine powder or the like is formed on at least one surface with a thickness of 0.001 to 5 μm, and at least the other surface 1 to 2,000 pieces / mm ² of surface protrusions having a height of 0.1 to 5 μm are provided on the surface, and at least one of various uneven patterns such as wavy, scale-like, satin-like, or leather-like patterns is combined. It is characterized by.

  According to a fourth aspect of the present invention, in the polypropylene sheet according to any one of the first to third aspects, at least the coating film formed on the one side surface includes silicone.

  A polypropylene sheet packaging container according to a fifth aspect of the present invention is characterized in that the polypropylene sheet according to any one of the first to fourth aspects is punched, bent, adhered, and assembled.

  A polypropylene sheet molded product according to a sixth aspect of the present invention is obtained by thermoforming the polypropylene sheet according to any one of the first to fourth aspects.

  The present invention eliminates or almost eliminates measures for improving slip properties such as aging, kneading of an antistatic agent or slip agent, and powder dispersal, and can improve slip properties with immediate effect and sustainability. A method for producing a polypropylene sheet can be provided.

  In addition, for various polypropylene sheets, the level of ink adhesion strength and adhesive adhesion strength can be improved, and the slip property between sheets can be improved. Two sheets are stacked during printing, punching, and adhesive pasting. Double feeding is eliminated, and the sheet can be bent smoothly into a clear case or the like.

  The best mode for carrying out the present invention will be described below with reference to examples.

  In order to solve the above-described conventional problems, the present invention is a process in which a PP single-layer sheet or a PP multi-layer sheet is processed into a single wafer cut plate for any of the above-mentioned special size or standard size. Two functions are added to add functions.

  In one processing, a synthetic resin such as urethane resin or polyester resin is diluted with a solvent and applied to at least one surface of the PP sheet in order to improve the printing ink adhesion strength to the sheet and the adhesion strength between the sheets. It is something to work on. As the solvent, water, alcohol, organic solvent, or the like can be used. In addition, it is possible to smoothly feed sheets one by one without problems during printing, punching, pasting glue (adhesive), double sheet feeding, that is, double sheet feeding. In addition, various antistatic agents may be added to the coating solution. As an auxiliary material for improving the slip property, silicone, various waxes, inorganic and organic fine powders, which are unlikely to obstruct printing and adhesion, can be supplementarily added. About these coatings, an equivalent effect can be obtained using the same or similar coating agent used in the method (Japanese Patent Application No. 2004-227550) related to the PET sheet proposed by the applicant of the present application. However, it has been confirmed by experiments conducted by the inventors. In addition, regarding the additional use of fine powder or the like, in the case of performing printing by back printing, at least the printing surface on the upper surface of the PP sheet is free from powder.

  In another process, in order to improve the slip property of the sheet, the heated sheet is pinched with an embossing roll and a general-purpose roll, and at least one surface of the sheet is roughened to form uneven projections. What is necessary is just to form an uneven | corrugated shape by making the kind of embossing roll different. Moreover, you may form the said unevenness | corrugation by the mechanical embossing by a sandblast roll, a rubber embossing roll, a metal embossing roll, etc., or chemical embossing.

For this embossing, surface protrusions having a height of 0.1 to 5 μm may be provided at 1 to 2,000 pieces / mm ² on the surface of at least one side of the sheet to be processed, wavy, scale-like, satin-like, Irregularities of various embossed patterns such as leather texture may be provided, or surface protrusions may be formed by appropriately combining these.

  In addition, by forming a combination of sharp and small embosses and large irregularities such as various embossed patterns on the surface of at least one side, the sheet slipping property, anti-blocking property, adhesiveness of printing ink, adhesive strength of adhesives, and scratches The characteristics are greatly improved. That is, when the PP sheet is embossed, an air layer is created between the sheets, and the slip property between the sheets is improved. For this reason, during printing, punching, and pasting, the stacked sheets are overlapped and fed. This makes it possible to smoothly process sheet folding boxes such as clear cases.

  In addition, the adhesion strength of the ink to the sheet and the adhesive strength of the glue can be improved by applying urethane resin, polyester resin, acrylic resin or the like. When UV offset printing is performed on a sheet cut sheet of a PP sheet coated with urethane resin, the ink adhesion strength to the sheet does not require OP (overprinting) varnish. It did not peel off and the printing finish was improved. Further, hot melt adhesion between PP sheets subjected to the above-described processing, adhesion by an instantaneous adhesive after application of an olefin sheet primer (undercoat), and the like were also improved.

  The combination of the coated resin film and the embossing on at least one surface of the PP sheet further improves the slip property, anti-blocking property, and adhesion of the printing ink to the sheet. In particular, after forming a roll (roll-shaped) sheet in a vacuum or forming it with air pressure, when the sheet molding is overlaid with a die press machine, etc., some wrinkles remain even if the wrinkles return to a slight glossy state. Because of the effect of the coating agent, there is slipping, so the overdrawing work can be done smoothly, and the overlapped moldings can be peeled off one by one with an automatic machine or by hand, so the handling of the moldings can be streamlined. it can.

  An example of the composition of the sheet coating agent performed by the inventors of the present application, coating film thickness, and surface unevenness is shown in the table of FIG. 1, and quality evaluation of the PP sheet coated with the sheet front and back is shown in the table of FIG.

  In addition, the PP sheet sheet cutting plate according to the present invention, after silk screen printing, UV offset printing, and hot stamping, is fed one by one by a punching machine called Heidelberg or Orton, The sheet is punched with a BIK blade, and then hot-melt adhesive and primer (undercoat) treatment is performed with a sack machine, glued with instant adhesive or instant adhesive only, or ultrasonically bonded, etc. It was suitable for making a clear case (sheet folding box) with three-dimensional adhesion. Moreover, it was suitable also for vacuum-forming a roll (roll form) sheet | seat, carrying out a pneumatic molding, and pile-up with a die press machine etc.

  The other examples of the sheet coating agent formulation example, coating film thickness, and surface irregularities performed by the inventors of the present application are shown in the table of FIG. 3, and the quality evaluation of the PP sheet coated with the sheet front and back is shown in the table of FIG. In the example of FIG. 3, the antistatic agent: A is an acrylic amphoteric antistatic agent, the antistatic agent: B is a polyester antistatic agent (including waxes), and the curing agent: C is Antistatic agent: B curing agent.

The figure which shows an example about the compounding example of a sheet coating agent, coating film thickness, and surface unevenness as a table The figure which shows an example of quality evaluation of the PP sheet which has been coated on the front and back of the sheet as a table The figure which shows the other example about the compounding example of a sheet coating agent, coating-film thickness, and surface asperity as a table | surface The figure which shows as a table | surface the other example of quality evaluation of sheet | seat front and back coated PP sheet

Claims (6)

A coating film of synthetic resin, wax, surfactant, inorganic / organic fine powder or the like is formed on at least one surface with a thickness of 0.001 to 5 μm, and at least 0.1 to 5 μm in height on the other surface. A polypropylene sheet comprising 1 to 2,000 surface protrusions / mm ² . A coating of synthetic resin, wax, surfactant, inorganic / organic fine powder or the like is formed on at least one surface with a thickness of 0.001 to 5 μm, and at least the other surface is wavy, scale-like, satin-like, A polypropylene sheet provided with at least one of irregularities of various texture patterns such as leather texture. A coating film of synthetic resin, wax, surfactant, inorganic / organic fine powder or the like is formed on at least one surface with a thickness of 0.001 to 5 μm, and at least 0.1 to 5 μm in height on the other surface. A polypropylene sheet comprising 1 to 2,000 surface protrusions / mm ² and a combination of at least one of irregularities such as wavy, scale-like, satin-like, and leather-like patterns. . 4. The polypropylene sheet according to claim 1, wherein silicone is contained in at least the coating film formed on the one side surface. A polypropylene sheet packaging container, wherein the polypropylene sheet according to any one of claims 1 to 4 is assembled by punching, bending, bonding, or the like. A polypropylene sheet molded article obtained by thermoforming the polypropylene sheet according to any one of claims 1 to 4.