JPH0431935B2 - - Google Patents

Description

[Detailed description of the invention]

[]Object of the Invention The present invention relates to a plastic container with clear printing, excellent gloss and rigidity. More specifically, the main layer is a propylene resin containing an inorganic filler, and the main layer contains di(methylbenzylidene).
Sorbitol to propylene resin: 0.01~
It relates to a plastic container made of a sheet obtained by laminating printed films of propylene resin containing 1.5% by weight,
The object of the present invention is to provide a plastic container with clear printing and excellent gloss and rigidity. []Background of the Invention Materials conventionally used for plastic containers include propylene resins, vinyl chloride resins, styrene resins, and ABS resins.
However, each material has its advantages and disadvantages, and its use is often restricted depending on the intended use of the resulting container. For example, vinyl chloride resins have excellent transparency and rigidity, but have problems with waste pollution, and styrene resins have weaknesses in heat resistance and chemical resistance. In addition, ABS resin is expensive and its uses are limited.
Furthermore, propylene resins have the advantage of having fewer waste pollution problems, excellent heat resistance and chemical resistance, and are inexpensive, but they are less rigid than vinyl chloride resins, styrene resins, and ABS resins. Has low disadvantages. Therefore, in order to improve this drawback of propylene resins, it is widely practiced to incorporate inorganic fillers such as talc and calcium carbonate. Rigidity can be improved by adding an inorganic filler to propylene resin, but if the manufactured sheet is thermoformed using pressure forming or vacuum forming, even if the sheet is glossy, As a result of molding, only containers with lost luster can be obtained, and cannot be used in applications where surface appearance is important. In general, there are many demands for plastic containers that emphasize surface appearance, and in order to meet these demands, containers are molded and then printed using a curved surface printing machine. Now that this has been satisfied, there is currently a demand for a container with an even better appearance. However, these methods have problems such as increased costs because printing is performed after the container is molded. []Structure of the Invention Based on the above, the present inventors conducted various searches in order to obtain a plastic container that not only has clear printing but also has excellent gloss and rigidity while exhibiting the characteristics of propylene resin. As a result, the melt flow rate (measured in accordance with JIS K-6758, hereinafter referred to as "MFR") was 0.01 to 5.0 g/10.
The main layer is an inorganic filler-containing propylene resin consisting of a propylene resin containing 10% to 70% by weight of an inorganic filler, and di-(methylbenzylidene) sorbitol is added to the main layer relative to the propylene resin.
It has been discovered that a plastic container made of a sheet obtained by laminating printed films of propylene resin containing 0.01 to 1.5% by weight not only has clear printing but also has extremely high gloss and rigidity. , arrived at the present invention. [] Effects and Applications of the Invention The plastic container obtained by the present invention exhibits the following effects including its manufacturing process. (1) It can be easily produced by a method commonly used in the field of propylene resins. (2) It is inexpensive and clearly printed. (3) Extremely good rigidity and gloss. (4) Since the film is printed, printed containers can be easily manufactured without using a commonly used curved surface printing machine. Since the plastic container obtained according to the present invention exhibits the above-mentioned effects, it can be used in a wide variety of ways. Typical uses are shown below. (1) Trays for meat, side dishes, etc. (2) Cups for pudding, jelly, frozen desserts, yokan, margarine, etc. (3) Cases for interior confectionery materials (4) Dividers for gifts (5) Lunch containers (6) Various lids Class (7) Automotive interior materials (8) Parts and cases for home appliances [] Specific description of the invention (A) Main layer (propylene resin containing inorganic filler) (1) Propylene resin Manufacture of the main layer of the present invention Propylene resins used for this purpose include propylene homopolymers and random or block copolymers of propylene with ethylene and/or other α-olefins having at most 12 carbon atoms (ethylene and other α-olefins). - The copolymerization ratio of olefin is at most 30% by weight in total. The MFR of these propylene resins is generally 0.01 to 5.0g/10
minutes, preferably 0.05 to 4.0g/10 minutes,
Particularly suitable is a propylene resin of 0.1 to 4.0 g/10 min. If a propylene resin with an MFR of less than 0.01 g/10 minutes is used, the moldability of the sheet will be poor and it will be difficult to obtain a good sheet. on the other hand,
If a propylene resin exceeding 5.0 g/10 minutes is used, drawdown will be large during thermoforming and a good container will not be obtained. These propylene-based resins carry a transition metal compound (e.g., a titanium-based compound or a transition metal compound) as a carrier (e.g., a magnesium-based compound,
Propylene is homopolymerized or propylene and ethylene and/or the other α-olefins mentioned above, by random or block copolymerization. (2) Inorganic filler The inorganic filler used to produce the main layer of the present invention is one that is generally widely used in the fields of synthetic resins and rubber. These inorganic fillers are preferably inorganic compounds that do not react with oxygen and water and do not decompose during kneading and molding. The inorganic fillers include metals such as aluminum, copper, iron, lead and nickel, oxides of these metals and metals such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony and titanium, and their water. It is broadly classified into compounds such as hydrates (hydroxides), sulfates, carbonates, silicates, their double salts, and mixtures thereof. Typical examples of the inorganic filler include the metals mentioned above, aluminum oxide (alumina), its hydrates, calcium hydroxide, magnesium oxide (magnesia),
Magnesium hydroxide, zinc oxide (zinc oxide), lead oxides such as red lead and lead mortar, magnesium carbonate, calcium carbonate, basic magnesium carbonate,
White carbon, asbestos, mica, talc, glass fiber, glass powder, glass beads, clay, diatomaceous earth, silica, wollastonite, iron oxide, antimony oxide, titanium acid (titania), lithopone, pumice powder, aluminum sulfate ( plaster, etc.),
Mention may be made of zirconium silicate, zirconium oxide, barium carbonate, dolomite, molybdenum disulfide and iron sand. Among these inorganic fillers, those in powder form have a diameter of 30 microns or less (preferably 10 microns or less).
(microns or less) is preferable. In addition, fibrous materials have a diameter of 1 to 500 microns (preferably 1 to 500 microns).
300 microns) and a length of 0.1 to 6 mm (preferably 0.1 to 5 mm). Furthermore, it is preferable that the diameter of the flat plate is 30 microns or less (preferably 10 microns or less). Among these inorganic fillers, those in the form of flat plates (flake) and those in the form of powder are particularly suitable. (3) Production of inorganic filler-containing propylene resin The inorganic filler-containing propylene resin of the present invention can be produced by uniformly mixing the propylene resin and the inorganic filler. The composition ratio (content ratio) of the inorganic filler in the inorganic filler-containing propylene resin is 10 to 70% by weight, preferably 15 to 70% by weight, especially 20% by weight.
~70% by weight is preferred. Inorganic Filler If the proportion of the inorganic filler in the propylene resin is less than 10% by weight, the resulting container will lack rigidity. On the other hand, if it exceeds 70% by weight, the impact resistance of the resulting container will be significant, resulting in a container that is not suitable for practical use. Additionally, the total composition has a density of at most 50% by weight.
0.910 to 0.975 g/cm ³ of ethylene resin may be blended. In producing the inorganic filler-containing propylene resin of the present invention, the purpose can be achieved by uniformly mixing the propylene resin and the inorganic filler. That is, the compositions of the present invention may be dry blended using mixers commonly used in the polyolefin industry such as Henschel mixers, Banbury mixers, kneaders, roll mills, and screw extruders. It can be obtained by melt-kneading. At this time, a homogeneous composition can be obtained by dry blending in advance and melt-kneading the resulting composition (mixture). In this case, the mixture is generally melt-kneaded and then formed into pellets, which are then subjected to the forming described later. Furthermore, when manufacturing the compositions of the present invention, all composition components may be mixed simultaneously. Alternatively, a masterbatch may be prepared by mixing some of them in advance, and the remaining composition components may be mixed into the resulting composition (masterbatch). In short, in order to produce the composition of the present invention, the purpose can be achieved by adjusting the composition proportions of all the components to be uniform and uniform. (B) Printed film This film is used to cover the main layer thus produced. (1) Propylene Resin The propylene resin used to produce this film is the same as the propylene homopolymer and/or random or block copolymer used to produce the main layer above, except for MFR. It contains di-(methylbenzylidene) sorbitol. The amount of di-(methylbenzylidene) sorbitol to be blended is 0.01 to 1.5% by weight, preferably 0.05 to 1.0% by weight, particularly preferably 0.1 to 1.0% by weight, based on the propylene resin. If a propylene resin containing less than 0.01% by weight of di-(methylbenzylidene) sorbitol is used, the gloss of the printed film decreases during thermoforming, making it impossible to produce containers with sharp prints. On the other hand, if more than 1.5% by weight of propylene resin is used, di-(methylbenzylidene) sorbitol becomes a filler, and the film loses its luster, making it impossible to produce containers with clear prints. The MFR of this propylene resin is usually 0.01~
100g/10 minutes, preferably 0.05-10g/10 minutes,
Particularly suitable is 0.1 to 50 g/10 minutes. MFR
If less than 0.01g/10 minutes of propylene resin is used,
Poor formability. On the other hand, if a propylene-based resin exceeding 100 g/10 minutes is used, moldability is poor and a good film cannot be produced. In producing the di-(methylbenzylidene)sorbitol-containing propylene resin of the present invention,
The objective can be achieved by uniformly mixing the propylene resin and di-(methylbenzylidene)sorbitol. That is, the compositions of the present invention may be dry blended using mixers commonly used in the polyolefin industry such as Henschel mixers, Banbury mixers, kneaders, roll mills, and screw extruders. It can be obtained by melt-kneading. At this time,
A uniform composition can be obtained by dry blending in advance and melt-kneading the resulting composition (mixture). In this case, the mixture is generally melt-kneaded and then formed into pellets, which are then subjected to the forming described later. Furthermore, when manufacturing the compositions of the present invention, all composition components may be mixed simultaneously. Alternatively, a masterbatch may be prepared by mixing some of them in advance, and the remaining composition components may be mixed into the resulting composition (masterbatch). In short, in order to produce the composition of the present invention, the purpose can be achieved by adjusting the composition proportions of all the components to be uniform and uniform. This propylene resin may be used as a composition by adding the additives described below by the mixing method described above. Additionally, the total composition has a density of at most 50% by weight.
0.910 to 0.975 g/cm ³ of ethylene resin may be blended. Whether it is the olefin resin mentioned above or this di-(methylbenzylidene) sorbitol-containing propylene resin, stabilizers against heat, light (ultraviolet rays) and oxygen, and flame retardants, which are commonly used in the field of olefin resin, may be added, if desired. Additives such as a curing agent, a lubricant, a processability improver, and an antistatic agent may be added (blended) within a range that does not impair the above-mentioned effects (characteristics). (2) Printing A method generally used for synthetic resin films or sheets, in which the above propylene resin or propylene resin mixed with additives is formed into a film as described below, and the surface is corona treated. Printed by. Printing methods include gravure printing, offset printing, flexo printing, letterpress printing, and screen printing. (C) Production of film and sheet (main layer) The inorganic filler-containing propylene resin constituting the main layer of the present invention is molded into a sheet by the molding method described below. Further, the printed film is formed into a film as described below. (1) Molding method Whether manufacturing a sheet of propylene resin containing an inorganic filler as the main layer or a printed film, the molding method generally used in the field of olefin resins should be applied. Bye. Typical examples of this molding method include the T-die method, the inflation method, and the calendar method. (2) Thickness The thickness of the printed film is usually 5 to 300 microns, preferably 5 to 250 microns, especially
10-200 microns is preferred. If the thickness of the printed film is less than 5 microns, the printed film will be torn or uneven during thermoforming, and it will be difficult to produce a good film. On the other hand, if it exceeds 300 microns, the proportion of this film will be high and the rigidity of the resulting container will be low, both of which are undesirable. However, where A is the thickness of the main layer and B is the thickness of the printed film, B/A must be 1.0 or less. (D) Manufacture of laminate and container (1) Manufacture of laminate To manufacture the container of the present invention, first, the sheet of propylene resin containing inorganic filler constituting the main layer manufactured as described above and A laminate is produced with a printed propylene resin film covering this sheet. This lamination method may be a method of laminating sheets or films generally practiced in the field of synthetic resins. Typical lamination methods include dry lamination and extrusion lamination. When producing this laminate, sheets and films may be produced in advance by the method described above and then laminated. Alternatively, the printed film may be preformed and the laminate may be produced while producing the sheet. The thickness of the laminate (sheet) produced in this way is usually 0.1 to 5.0 mm, preferably 0.2 to 4.0 mm, and particularly preferably 0.3 to 2.5 mm. If the thickness of the sheet is less than 0.1 mm, the rigidity will be insufficient and the container described below cannot be manufactured. On the other hand, if the thickness exceeds 5.0 mm, it is difficult to manufacture a container from the sheet, making it impossible to obtain a good container. In the case of melt-kneading as described above, in the production of inorganic filler-containing propylene-based resin sheets and printed propylene-based resin films, and in the production of laminates made of these, propylene-based resins are used. Although the temperature is above the melting point of the resin, it must be carried out at a temperature that does not cause the propylene resin to deteriorate. from these things,
In either case, it must be carried out in a temperature range of 140°C to 300°C. (2) Manufacture of containers Containers can be manufactured from the laminate produced in this way by using any of the vacuum forming methods, pressure forming methods, and press forming methods that are commonly practiced in the field of propylene resins. Just adopt it and manufacture it. Note that these molding conditions depend on the molding method,
The optimum conditions are determined by the mutual relationship among the type of molding machine used, the structure of the mold, and the molding conditions (for example, molding temperature, pressure), so it is difficult to limit the conditions. []Examples and Comparative Examples The present invention will now be explained in more detail with reference to Examples. In the Examples and Comparative Examples, the gloss of the container was measured on the outer surface of the container in accordance with JIS Z-8701. In addition, for rigidity, cut out the bottom of the container,
Measured according to ASTM D-747. moreover,
The sharpness of the print was determined visually. It is shown below. 〇: The clarity of the printed pattern has not changed from before the container was molded. ×: The visibility of the printed pattern has changed due to the molding of the container. The types and physical properties of the ethylene resin and inorganic filler are shown below. [(A) Propylene resin] As the propylene resin, propylene homopolymer with an MFR of 0.5 g/10 minutes [hereinafter referred to as "PP(1)"], propylene homopolymer with an MFR of 7.0 g/10 minutes, Combined [hereinafter referred to as “PP(2)”], MFR is 0.7g/
Propylene-ethylene block copolymer [ethylene content 18.0% by weight, hereinafter referred to as "PP(3)"]
], propylene with an MFR of 2.0g/10 min.
Ethylene random copolymer [ethylene content 4.0
weight%, hereinafter referred to as “PP(4)”] and MFR
A propylene-ethylene random copolymer (ethylene content: 1.5% by weight, hereinafter referred to as "PP(5)") was prepared at a rate of 12.0 g/10 minutes. [(B) Ethylene Resin] As the ethylene resin, an ethylene homopolymer (density 0.960 g/cm ³ , hereinafter referred to as "PE") having an MFR of 0.5 g/10 minutes was used. [(C) Inorganic filler] As an inorganic filler, talc with an average particle size of 3 microns (aspect ratio approximately 7), talc with an average particle size of 8
Mica (aspect ratio: about 8) having a particle size of microns and calcium carbonate (hereinafter referred to as "CaCO ₃ ") having an average particle size of 0.1 microns were used. Examples 1 to 6, Comparative Examples 1 to 6 The inorganic filler-containing propylene resin forming the main layer was composed of a propylene resin and an inorganic filler (Examples 1, 2 and 6 and Comparative Examples 1 to 3 and 5 Furthermore, ethylene resin was added) and dry blended using a Henschel mixer (the types and amounts of the inorganic filler, propylene resin, and ethylene resin are shown in Table 1). Each mixture obtained was transferred to a vented extruder (diameter 65
pellets (composition) at a temperature of 230 °C using
was manufactured. In addition, the printed films were produced by using the T-die method using the propylene resin whose compounding amount of di-(methylbenzylidene) sorbitol is shown in Table 1. The obtained film was corona treated to give a surface leakage index of 42 dynes, and then gravure printing was performed to produce a printed film. The pellets forming the main layer produced as described above were extruded using an extruder (diameter 65 mm) equipped with a T-die at a resin temperature of 240 DEG C., and a sheet was formed by roll compression. At this time,
The printed films listed in Table 1 are merged at the inlet of the pressure roll and thermally laminated to the sheet forming the main layer by the heat pressure of the roll,
Sheet with the thickness shown in Table 1 (width
300mm) was manufactured. Each sheet thus obtained was processed using a roll continuous thermoforming machine (manufactured by Asano Research Institute, model name: FLX-02, oven model:
(double-sided infrared heating method) (height: 140 mm, width: 140 mm)
mm, depth 50mm). The gloss and rigidity of the printed surface of each container obtained were measured. Additionally, the sharpness of the print on the container was visually determined. The results are shown in Table 2.

【table】

【table】

【table】

[Table] The sheet obtained in Comparative Example 6 was subjected to vacuum forming, pressure forming and press forming, but
Wrinkles were formed on the surfaces of both. From the results of the above Examples and Comparative Examples, it is clear that the containers obtained by the present invention not only have excellent surface gloss and rigidity, but also have clear printed patterns, whereas the main layer is composed of the composition of the present invention. If the ratio is outside the range, a highly rigid container will not be obtained, and if the printed film is outside the range of the present invention, the gloss will be poor or
It is clear that only containers with blurred printed patterns are obtained.

[Claims]

1 30 to 80% by weight of a polyolefin resin made by mixing a polypropylene resin and a polyethylene resin at a ratio of 9:1 to 1:9 (weight ratio), and an inorganic filling consisting of talc and titanium oxide. The beverage container is made of a resin composition material containing 70 to 20% by weight of an agent and has folded ribs, the folded ribs having a first bent part I ₁ , a horizontal part D, and a second bent part. I ₂ and the tip H, and the length of the tip H and the horizontal part D is H=(1±
0.3)×D, and the bending angle θ of the tip H is θ=5±3 degrees. 2. The container according to claim 1, wherein the horizontal distance of the first bent portion _I1 is (0.4±0.2)×D. 3. The container according to claim 1, wherein the angle α of the bending point 2 is 0 to 30 degrees.