JPS608036A - Thermal molding product - Google Patents

Abstract

PURPOSE:To obtain a thermal molding product having a paper-like appearance with specific ranges of whiteness and glossiness for most of its peripheral surface from a polyolefinic resin mixed with an inorganic filler. CONSTITUTION:A polyolefinic resin (e.g., polypropylene resin) in 40-75wt% preferably is mixed with 25-60wt% an inorganic filler (e.g., talc) and 1.5-8wt% titanium oxide (e.g., titanium dioxide), together with an unsaturated carboxylic acid, an antioxidant, an ultraviolet rays absorber, an antistatic agent, a lubricant, a pigment, etc., as needed, by a usual mixing method. The mixture is molded into a sheet by a sheet extrusion molding method, etc. The sheet is subjected to a secondary molding process, e.g., vacuum molding, etc., to obtain an aimed thermal molding having a whiteness of 90% or more and a glossiness GS (60%) of 10% or less for most of its appearance. USE:Packing container, food container, beverage container, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thermoformed articles, and more particularly to thermoformed articles exhibiting a paper-like appearance.

Conventionally, after blending an inorganic filler with a polyolefin resin and melt-kneading it, it is made into a sheet by a calendaring method or an extrusion molding method, and this sheet is used to create various thermoformed products by secondary thermoforming such as vacuum forming and/or pressure forming. is being manufactured. These thermoformed products made from polyolefin resins containing inorganic fillers have high strength and rigidity, and when disposed of by incineration after use, they burn a low amount of calories, causing them to melt and solidify or emit black smoke. It is also excellent in terms of pollution prevention, as it does not cause any problems, and it is highly anticipated that it will reduce the amount of resin used by incorporating an inorganic filler.

However, these conventional thermoformed products have a relatively low degree of whiteness and are glossy, giving a strong impression that they are plastic. Especially thickness 1s+m
The following thin molded products remain transparent and do not have a satisfactory appearance and texture compared to paper containers. Therefore, although these conventional thermoformed products have excellent properties and productivity, the reality is that they are not used at all in fields where a high-class look is particularly required.

The object of the present invention is to provide a thermoformed product that overcomes these conventional drawbacks.

That is, the present invention provides a thermoformed product made of polyolefin resin containing an inorganic filler, in which the whiteness of most of the outer surface is 9.
The object of the present invention is to provide a thermoformed article characterized by having a glossiness as (soo) of 0% or more and a glossiness as (soo) of 10% or less.

In the present invention, the inorganic filler-containing polyolefin resin is, more specifically, a composition comprising a polyolefin resin, an inorganic filler, and titanium oxide.

The polyolefin resin in the present invention is not particularly limited and may include various resins, such as polypropylene resin, polyethylene resin, and polybutene resin.

Examples of the polypropylene resin include propylene homopolymers, block copolymers and random copolymers of propylene and 30% by weight or less of an α-olefin such as ethylene, and mixtures thereof. The melt index of the brobylene resin is generally 0.1 to 57/10 minutes, preferably 0.2 to 3.
y/1o min, more preferably 0.5-1.5p/10
It belongs to fi. In this case, if the melt index exceeds 5 p/10 minutes, the melt strength of the sheet will be low, while if it is less than 17/1 o minutes, the fluidity will be poor, and it will be difficult to combine with inorganic fillers such as talc or titanium oxide. The uniform kneading properties of these materials are insufficient, and secondary moldability such as thermoforming becomes difficult.

On the other hand, there are various types of polyethylene resins, such as high-density polyethylene, medium-density polyethylene, and low-density polyethylene, and in addition to ethylene homopolymers, other α-olefins (propylene and Random or block copolymers are available. Here, high-density polyethylene has a density of 0.940 to 0.9707/crl, medium-density polyethylene,
Low-density polyethylene includes high-pressure polyethylene, medium-density polyethylene,
Ethylene and propylene obtained by low pressure method, butene-1゜4-methylpentene-1, octene-1, etc. with 3 to 3 carbon atoms
A copolymer of 12 α-olefins, so-called linear low density polyethylene (LLDPI), is used. Also,
The melt index of this polyethylene resin is usually 0.02 to 10.0 g-710 minutes, preferably 0.02 to 10.0 g-710 minutes.
03 to 5.07710 minutes, more preferably 3- is 0.04 to 2.07/10 minutes. If the melt index of the polyethylene resin is outside the above range, it is unfavorable in terms of melt-kneaded sheet formability and secondary formability such as thermoforming.

The polyolefin resin in the present invention may be the above-mentioned polypropylene resin, polyethylene resin, polybutene resin, etc., used alone or appropriately mixed, but lighter deep containers can be formed by vacuum forming or pressure forming. In order to carry out continuous mass production by secondary molding, it is effective to use a mixture of the above-mentioned polypropylene resin and polyethylene resin. The mixing ratio of polypropylene resin and polyethylene resin in this mixture is not particularly limited, but generally the former: the latter = 9 = 1 to 1:9 (
(weight ratio), preferably 7:3 to 3 (weight ratio).

The blending ratio of the polyolefin resin in the present invention is not particularly limited, but it should normally be 30 to 80% by weight, preferably 40 to 75% by weight of the entire composition.

4- In any case, the polyolefin type 17 resin depends on the amount of inorganic filler to be added, the intended use of the molded product, and
The most suitable one can be selected depending on the size, depth, shape, molding method, etc. In this case, there is no problem in combining various polymers and grades, as well as combining two or more different polyolefin resins. do not have.

Next, various kinds of inorganic fillers can be used in the present invention, and there are no particular limitations. For example, Merck.

Calcium carbonate, barium sulfate, calcium sulfate.

Examples include calcium sulfite, silica, etc., but it is particularly preferable to use Calcium sulfite. When using Merck, there are no particular restrictions on its type or shape, but it is usually hydrated magnesium silicate with an average particle size of 5 to 30μ, preferably 10 to 20μ, and its composition is 5in25
It consists of 0 to 65% Mg, 25 to 40% Mg, and other components, and has a loss on ignition of 1% or less. The blending ratio of this inorganic filler varies depending on the shape of the intended molded product, the purpose, etc., and cannot be determined unambiguously, but it is usually 20 to 70% by weight of the entire composition, preferably 25% by weight of the entire composition. It is set in the range of 60 to 1%. If the amount of inorganic bamboo phosphor added is too large, the rigidity and incineration properties will be improved, but the secondary coloring properties such as melt-kneading, sheet formability, and thermoforming will be reduced.

In addition, when using Merck, a variety of materials can be used as mentioned above, but when used as containers for food-related fields, it is preferable to use materials that are free of eluted substances and odors. You can also perform purification processing. Note that this talc does not require any additional means such as surface treatment, but if a mechanical T11 degree is required for non-food applications, talc Table 1ff7 treated to make it lipophilic can be used. It's okay. Specific examples of these lipophilic treatments include surfactants with lipophilic groups, polymerizable monomers that react with heating to form lipophilic groups, oligomers, and even silane coupling agents. and so on.

Furthermore, in the present invention, titanium oxide is used in addition to the above-mentioned components. Titanium oxide in the present invention usually refers to titanium dioxide (Tie), but it may also be mixed with a small amount of titanium monoxide (T10) or dititanium trioxide (Tl2O3).

In addition, there are no particular restrictions on the shape etc. of this titanium oxide, but the average particle size is generally 0.05 to 2μ, preferably 0.
．． It is in the form of granules or powders of about 1 to 1 μm.

Furthermore, the blending ratio of titanium oxide varies depending on various conditions, and although it is difficult to determine the exact ratio, when a sheet with a thickness of 18 mm is formed from the composition, the total light transmittance of this sheet is 3.
% or less, particularly 2% or less, and specifically, it is selected in the range of 1 to 10% by weight, preferably 1.5 to 8% by weight of the entire composition. Conventionally, the proportion of titanium oxide added has generally been small, usually 0.5% by weight or less of the total composition. However, in the present invention, relatively malleable titanium oxide is blended, and in addition, it is blended with an inorganic bamboo starch agent, especially talc, and is completely @-quality compared to the conventional products.

As described above, the inorganic bamboo resin compound is used in the production of a thermoformed product made of polyolefin resin in the present invention, and if necessary, ethylene-propylene rubber,
Rubbers such as ethylene-propylene-diene rubber, polyolefin resins modified with unsaturated carboxylic acids such as maleic anhydride or derivatives thereof, etc. can also be added. Also, various antioxidants, ultraviolet absorbers, and antistatic agents.

It is also possible to add lubricants, pigments, etc.

The thermoformed product of the present invention is made from the three components detailed above as raw materials, which are formed into a sheet and then thermoformed into a specific shape.

That is, the above-mentioned three components and desired components are thoroughly kneaded using a conventional method, such as a roll, a Banbury mixer, a 9-screw extruder, or a multi-screw extruder, and then formed into a sheet by a sheet extrusion method, a calender roll method, etc. do. The thickness of the sheet is usually 0.2 to 5 mm.

Next, the sheet thus obtained is subjected to secondary thermoforming such as vacuum forming, pressure forming, or a combination thereof to produce thermoformed products of various shapes. Note that the expansion magnification is 1.5 or more. By adopting this molding method, it is possible to mold many pieces at once, the molding cycle is short, and continuous mass production is possible.

Furthermore, by inwardly curling the rib portions around the container opening of the thermoformed product obtained by these thermoforming processes, the product can be easily curled, making it more desirable as a beverage container.

The thus obtained thermoformed article of the present invention has a whiteness of most of the surface of the thermoformed article of the present invention of 90% or more, preferably 92% or more. In addition, the gloss level is O8 according to ASTM D523.
(60°) is 10% or less, preferably 8% or less.

Further, the light transmittance according to ASTM D1005 is 5% or less.

Therefore, the thermoformed article of the present invention has the following excellent properties.

That is, (1) it has a high degree of whiteness and is not glossy, has a low light transmittance, and has a high hiding power, so the plastic feel is eliminated and it has a luxurious appearance, in other words, it has the appearance of a paper-like natural product. ■Not only does it look good, but it also feels like high-quality paper when you tap it on the skin. ■High strength, rigidity, and heat resistance.

Shows water resistance. ■When Merck is used as an inorganic filler, there is no burnt odor and the filler does not elute, making it highly safe. ■Good printability and paintability. Containers with various designs can be freely obtained, from zero circles to polygons, and even those with widened openings. ■It is easily deformed or destroyed by crushing it with strong force, and does not return to its original shape due to its elasticity, so the waste does not become bulky and is easy to dispose of. - Low heat generation, no damage to the furnace wall during incineration, no melting and solidification, no visible gas or black smoke, and excellent waste incineration performance. ■The molding cycle is short and continuous mass production is possible.

Therefore, the thermoformed product of the present invention can be used for various packaging containers.

It is expected that it will be effectively used as food containers and beverage containers.

Next, the present invention will be implemented and explained using 11. However, the present invention is not limited thereto.

Example Polypropylene homopolymer (density 0.91 f/cd
l.

Melt index 7, (MI) 0.6 p/10
) 20% by weight, high density polyethylene (density 0,964
f/c, tl.

46% by weight of Merck having an average particle size of 15μ and 4% by weight of titanium oxide were melt-kneaded using a Banbury mixer to obtain pellets. Next, the pellets were fed to an extruder for sheet production to obtain a talc-containing polyolefin resin sheet having a thickness of 1 mm.

Next, this sheet is pressure-formed into a cup-shaped thermoformed product (
Average diameter: 60 tmn, height: 90 mm, bottom thickness: 0.85 mm
A thickness of 0.66 mm) was obtained.

The whiteness at the center of the outer surface of the obtained thermoformed product was 94%, the gloss level 08 (6Q°) was 5.6%, and the total light transmittance at the bottom was 0.6%.
The thermoformed product had a total lateral light transmittance of 6.6% and had an excellent appearance with a luxurious feel. Also, the buckling strength is 1
It weighed 9.5 kg and had a lateral compressive strength of 1451.

Reference Example 11 - The whiteness of the outer surface of a commercially available high-quality paper beverage cup is 92
%, and the glossiness GS (60'') was 9.5%.

Patent applicant: Idemitsu Petrochemical Co., Ltd. 12-

Claims (1)

[Scope of Claims] 1. A thermoformed article made of polyolefin resin containing an inorganic filler, in which the whiteness of most of the outer surface is 90% or more,
A thermoformed product characterized in that the glossiness GS (doo) is 10% or less. 2 Claim 1 in which the inorganic filler is Merck
Thermoformed products as described in section.