JPH0281620A - Top-opening container made of poly-3-methylbutene-1 resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant container made of poly-3-methylbutene-1 resin. More specifically, a heat-resistant top-opening activator made of a rubbery α-olefin copolymer-containing poly-3-memelbutene-l resin that can withstand heating in a microwave oven and open use at temperatures of 160°C or higher, preferably 200°C or higher. With the increase in food consumption, there is an increasing demand for instant foods that shorten cooking time or are easy to prepare. These trends, together with the widespread use of microwave (open) ovens in recent years, are attracting attention to heat-resistant containers that can be used both in microwave ovens and open ovens.

[Conventional technology]

Expanded polystyrene has conventionally been widely used as containers for instant foods, but polystyrene has a low softening temperature and insufficient heat resistance for use in microwave ovens, open containers, etc.

Polypropylene is a resin with higher heat resistance than polystyrene. Containers made of polypropylene resin usually have sufficient heat resistance when heating foods with a high moisture content in a microwave oven, but containers made of polypropylene resin have sufficient heat resistance when heating foods with a high content of oil or fat at 160°C.
It cannot withstand more open use.

On the other hand, so-called easily crystallized polyethylene terephthalate (C-
Thin-walled containers made of (called PET) are also oil-resistant and are being used as containers that can be used in both microwave ovens and open containers.

[Problems to be solved by the present invention]

However, such polyethylene terephthalate containers have the following inadequacies.

First, although this type of instant food is often stored frozen, C-PET containers have insufficient impact resistance at low temperatures.

In addition, regarding heat resistance, C-PET containers range from 220°C to
Although it is said that it can withstand use at 230°C, when a C-PET container is actually applied to a household electronic open range, it is easily deformed at high temperatures and cannot be put to practical use.

Furthermore, after cooking, crystallization progresses and the impact resistance is significantly reduced. Furthermore, compared to glass containers, C-PET containers have
When heated with the same output, the content rises slowly, i.e.
High frequency usage efficiency is low.

[Means to solve problems]

In view of the current state of heat-resistant containers as described above, the present inventors conducted intensive studies on the application of poly-3-methylbutene-l, which is a polyolefin with a high melting point and high crystallinity, to the heat-resistant containers. The inventors have discovered that it is possible to obtain a heat-resistant container with good performance that improves the drawbacks of heat-resistant containers made of other resins, and has arrived at the present invention.

That is, in the present invention, the heat of fusion is r~/t, A cal/?
A top-opening container made of poly3-methylbutene-7 resin is obtained by forming a 3-methylbutene-l~α-olefin random copolymer into a sheet and then thermoforming.

The present invention will be explained in detail below.

The poly 3-methylbutene-7 resin used in the present invention is
- Random copolymers of methylbutene and other α-olefins having 2 to 20 carbon atoms. Such α-olefins include ethylene, propylene butene-11 hexene/
-/, octene-71decene-11dodecene-/, hexadecene-71octadecene-1, etc., and linear α
-Olefins are preferred.

For the copolymerization method, transition metal compounds and periodic table compounds are mixed in aliphatic, alicyclic or aromatic hydrocarbons such as butane, hexane, heptane, cyclohexane, benzene, etc., in liquid olefins, or in the absence of a solvent. , 3-methylbutene-1 and other α-olefins having 2 to 20 carbon atoms may be randomly copolymerized in the presence of an organometallic compound of Group 1 to Group 3 metals.

3-Methylbutene-! Two or more other α-olefins may be randomly copolymerized.

Furthermore, the concentration of other α-olefins relative to 3-methylbutene-l may be changed during the middle stage of the polymerization reaction, and a mixed composition of two types of random copolymerization with different composition ratios may be obtained.

There are no particular restrictions on the transition metal compound and organometallic compound of Group 1 to Group 3 metals of the periodic table, which are the catalysts, and those commonly used in the polymerization of olefins can be used.

Preferably Mg4T i H halogen and ether,
It is a combination of a solid catalyst component containing an electron-donating compound such as an ester, an organoaluminium compound, and, if necessary, an electron-donating compound such as an ether or ester. Such solid catalyst components are available from Tokukai Sho! 2-ta♂076
Publication No. 33-, 2 Hiro J7J' Publication, j3-♂3
? Publication No. 77, same! 3-ii7o♂ No. 3 Publication, same! It is described in Tar No. 620 Hiroshi Publication, J Tar No. 1i3o6 Publication, etc. Also, the aluminum content is the atomic ratio of aluminum to titanium. , is or less, and a combination of a solid titanium trichloride catalyst component containing a parenteral complexing agent and an organoaluminum compound, especially an aluminum dialkyl monohalide, and optionally an electron-donating compound such as an ether, ester, etc. is also suitable. used. Such a solid titanium trichloride catalyst component is
T issue, same j! -144j No. 2 Publication, same! ! -10
Publication No. 03, Publication No. J-2717/Publication, Publication No. J-3/IJ, Publication No. 11-/μoz-Hiro, J3-4
It is described in CψRiyo No. 2 Publication etc.

The polymerization temperature is 0, / j 0°C. Further, a molecular weight regulator such as hydrogen may be used if necessary.

The heat of fusion of the copolymer of 3-methylbutene-1 and other α-olefins having 2 to 20 carbon atoms used in the present invention is measured by a differential scanning calorimeter (DSC) and is t to C11t/l.
/ 1lait/f1 preferably 2ca1. / f
-/2 cat/t. Also, the melting point is 2j
O~300"C1 preferably 260"C~29! It is ℃. If the melting point is higher than the upper limit, the molding temperature is too high and polymer deterioration during molding is likely to occur. Further, below the lower limit, heat resistance is insufficient.

A polymer with a heat of fusion lower than the above range is a polymer with a high degree of copolymerization, but when molded into a container, it was found that not only high heat resistance could not be obtained, but also high impact strength could not be obtained.

On the other hand, a polymer with a heat of fusion higher than the above range has excessively high crystallinity and has poor moldability in sheet molding and thermoforming, making it impossible to obtain a molded product of the correct shape. of the composition, 32
The melt index measured according to ASTM DI23r at 0° C. is from o,i to 1009/10 minutes, preferably from 0.2 to 709/10 minutes. If the melt index is higher than the upper limit, the liquidity is good;
Although the sheet formability is good, on the other hand, there is drawdown of the sheet during thermoforming, and the formability during thermoforming is reduced. In addition, impact resistance also decreases.

If the melt index is lower than the lower limit, the impact strength is high, but molding becomes impossible or productivity becomes low.

Since the melt index of the poly-3-methylbutene-7 resin composition may change during molding, it is preferable that the melt index of the molded article is within the above range in order to obtain good physical properties.

Since the container of the present invention is used at high temperatures, it is important to select a heat stabilizer, and in particular, one that is less likely to scatter at high temperatures is preferred.

An example of such an additive is Irganox tot
o (product name; manufactured by Nippon Ciba Gaiki Co., Ltd.) and Irgafuos P-EPQ (product name; manufactured by Nippon Ciba Gaiki Co., Ltd.), Irganox toio, and MARKAO-4'/
MARKA
O-/r (product name; manufactured by Adeka Argus), MARKA
O-4! /JS (trade name; manufactured by Ateca Arcus) and in some cases, a combination of Irgafuos P--EPQ is used. In addition, Rasumitsu) HPM-/J (product name; Dai-Kogyo Seiyaku Co., Ltd.), Irgafuos 16♂ (product name;
(manufactured by Nippon Teva Gaiki Co., Ltd.), DSTDP, etc. are also effective.

As the antioxidant used in the present invention, especially at 20.0°C
For containers used at higher temperatures, only hindered phenolic antioxidants are used to avoid odor generation and discoloration of materials.
It is necessary to use a hindered phenol compound that satisfies the requirement that the zero weight reduction temperature is 220° C. or higher.

The /, 0 weight width reduction' temperature measured by TGA here refers to /, 0 weight width reduction' temperature under a total air flow rate of 1 minute. "Weight loss was measured at a heating rate of C7 minutes, and this is the temperature at which a weight loss of /, 0 weight range was observed.

Specific hindered phenolic antioxidants used in the composition of the present invention include, for example, pentaerythrityl-tetrakis [3-(3,!-di-t-butyl-hydroxyphenyl)propionate] and ．．
Davis (/,/-dimethyl゛-2-(β-(3-t-
It is desirable to use butyl-μm and drogacyj-methylphenyl)fluorinyloxy)ethyl]-λ, u, r, io -tetraoxysuspiro[j,j]launchan alone or in combination.

The amount of antioxidant added is 3-methylbutene-1 homopolymer or 3-methylbutene-1 and other α-
Q, 7 to ioo parts by weight of copolymer with olefin
The amount is 3 parts by weight, preferably 0.2 to 2 parts by weight. o, i
If the amount is less than 3 parts by weight, sufficient effect cannot be obtained, and if it is used in excess of 3 parts by weight, the effect will not increase and it will be economically disadvantageous.
J-do or deterioration of physical properties may occur, which is not preferable.

As a method for molding the heat-resistant container of the poly-3-methylbutene-1 resin composition of the present invention, preferably a thermoforming method is used. The thermoforming method is described in the "Practical Plastic Terminology Dictionary" (edited by Shoji Seto, Glasstics Ken Age, Showa 0) or the on-site manual "Thermoforming (vacuum forming, pressure forming)".
(Comprehensive Chemical Research New Edition, Asano Research Institute, written by Kazuo Asano)
It is a method of processing a sheet of thermoplastic resin, in which the heated and softened sheet is cooled while being deformed by some external force to produce a molded product. Examples include molding (vacuum, pressure forming), drape molding, reverse draw molding, air slip molding, plug assist molding, plug assist reverse draw molding, contact heating pressure molding, and the like. Normally, vacuum or pressure forming with plug assist is sufficient to obtain a molded product in the desired shape.

To outline vacuum and pressure forming, a sheet of the poly-3-methylbutene-l resin composition described above is molded, the sheet is then heated and softened, and the softened sheet is placed in a mold using vacuum and/or pressure. Spread and stretch uniformly. Thereafter, after crystallization has sufficiently progressed within the mold, the molded product is taken out from the mold. The sheet can be formed by a conventional method such as T-die extrusion. The thickness of the sheet is usually 200μm-2,jl, preferably 300μm
mN1. jIDI. If the thickness of the sheet exceeds this value, it becomes difficult to uniformly heat the sheet, and crystallization progresses unevenly in various parts of the sheet, which is not preferable.

The heating temperature of the sheet is 220 to 310°C, preferably SO to 300°C, but within ±20 of the melting point of the resin composition.
A range of 0.degree. C. is preferred, and a range of 15 to +lQ.degree. C. of the melting point is usually optimal.

Next, when the sheet becomes translucent by heating, it is desirable to apply vacuum or compressed air to form the sheet.

If the heating time is too long or the heating temperature is too high,
This is not preferable because it causes deterioration of the resin and decreases its physical properties.

The heating time is usually 30 seconds or less.

The mold temperature varies depending on the type of resin, but the temperature is 100~2JO°C.
% preferably l! The temperature is set between Q-220℃,
After the resin has sufficiently crystallized and the residual stress is limited, the molded product is removed from the mold. The wall thickness of the molded container is /00t4m~2B, preferably 200μm%/W
It is.

If the molding temperature is too low, molding stress remains and the heat distortion temperature decreases, which poses a practical problem.

Since the poly-3-methylbutene-l resin composition of the present invention crystallizes quickly, the mold holding time can be short, 2 seconds or more,
Usually 5 seconds or less is sufficient.

For this reason, it is possible to mold in a very short cycle. Moreover, the poly 3-methylbutene-7 resin of the present invention is
Because it has good mold releasability, it is easy to take out from the mold after molding, and has the advantage of having a low defective rate.

Regarding cooling of the container after being taken out from the mold, a cooling mold can be used as necessary.

The container used as a molded article in the present invention is a top-opening container. The term "open-top container" refers to a container that is open at the top and has self-shape retention, such as a tray-shaped, dish-shaped, cup-shaped, box-shaped container, or a container having a partition. For example, soft containers such as bags are not referred to as top-open containers in the present invention.

Poly 3-methylbutene of the present invention molded as described above
7. Containers made of resin compositions have high heat resistance, and polypropylene does not cause deformation.

Even when maintained at an ambient temperature of ℃, there is no deformation such as twisting or warping, and there is no problem of yellowing. Furthermore, by selecting an appropriate resin and molding conditions, it does not cause problems such as deformation or discoloration even under conditions of 200°C or higher, and has heat resistance up to 2≠0°C.

Furthermore, compared to C-PET, there is no drop in impact strength after heating, and in this sense, it can be said that it has high heat resistance. Regarding impact strength, at room temperature it is 50J4・crn/secondary light or above or lλ! It is more than @ffi/cm.

Note that normal temperature here refers to 20 to Q°C. In addition, the impact strength is particularly high at low temperatures (the falling weight impact strength at -20°C is over 10 kg-α/1000).

Furthermore, while the difference in impact strength between 30°C and -20°C is lower than Id/720 for commercially available C-PET products, the difference in impact strength at room temperature is about /2~t7s for the container of the present invention. It is characterized by a small drop in impact strength.

〔Example〕

Examples will be shown below, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Physical property values in the following examples were measured by the following method.

Melt index (Ml) is ASTM D/, 2
31 (320° C., 2./4 #load) using a Tata OQ type differential scanning calorimeter (DSC).

The melting curves were calculated for samples melted at 335°C for to minutes in a DSC apparatus and then slowly cooled at 16°C/min.
The temperature was raised at a rate of °C/min for measurement.

Beak top was used for the melting point. In cases where two or more peak tops were shown, each was also regarded as the melting point. In principle, the heat of fusion was determined by drawing a tangent to the base of the peak and calculating the area surrounded by the melting curve and the tangent.

0 The content of each component of the copolymer was determined by measuring a high-resolution ILMR spectrum at 370° C. and 13° C. using a JEOL FX200 NMR device (equipped with a high-temperature variable device).

0 Vacuum and pressure forming were performed using a vacuum pressure forming machine (with plug assist) manufactured by Asano Laboratory Co., Ltd. Molding conditions such as molding temperature and mold temperature are shown in Table 2 together with the physical property evaluation results.

For resin compositions having two or more melting points, the average value was determined, and the molding temperature was determined based on that value.

The shape of the mold is / j zX / 2. ! cm x depth 2
．． It is a 1 cm square container.

0 Measurement of heat resistance (open test) The molded product was placed in a gear open chamber set at 200°C, 230°C, 20°C, and 210°C, and after tr minutes, it was taken out and its appearance was confirmed. (Tapai Gear Open GPS-//C type was used for gear opening.) Measuring the heating rate of contents using a microwave oven Salad oil/
00 cc was added, and the internal temperature was measured over time to determine how easily the contents were heated. (The microwave oven used was a Mitsubishi Electric RO-/RI00 type electronic open range.

Samples of poly3-methylbutene-7 resin compositions used for falling weight impact strength measurements were heat-treated at 200°C/hr after molding, and commercially available C-PET containers were used as they were. It was measured with The measuring device is a drop tester made by Rheometrics, and the height of the falling weight is: r o, 2
yλm1 Falling weight Jj/17Ail, Falling weight speed! , 3.
Measured at 337M/S. Measurement temperature is 30℃ and -20℃
It is.

Measurements at low temperatures were performed after the temperature of the measurement chamber was cooled with liquid nitrogen to a predetermined temperature. The measured value was expressed by dividing the amount of energy required for fracture by the sample thickness.

A sample piece was cut out from the bottom of the container, fixed in a clamp with an inner diameter of 7.5 inches, and used for measurement.

Catalyst Production Example At room temperature, purified toluene (j/j, l) was placed in an autoclave having a volume/l that was sufficiently purged with nitrogen, and while stirring, n-butyl ether (t!) was added. , / 9 (0.1 mol), titanium tetrachloride 9μ, ri? (0,! mol) and diethylaluminum chloride 2 ffJ? (0.2 hirom
ol) was added to obtain a brown homogeneous solution. Then 30℃
The temperature rises to After 30 minutes, the temperature was raised to 0°C and kept at μO°C for λ time. After that, titanium tetrachloride (0,/7 mol) of 322 and tridecyl methacrylate (0,0 rm, ol) of /j, jf were added. r
The temperature was raised to ℃.

After holding at temperature for 2 hours, the granular purple solid was separated and washed with toluene to obtain solid titanium trichloride.0Resin Production Example-l Diethyl was thoroughly dried and replaced with argon in a 5 t capacity induction stirring autoclave. Aluminum monochloride / mmol and 3-methylbutene / 300
0 ytl was charged. Internal temperature? After raising the temperature to θ°C, the solid titanium trichloride catalyst component obtained in the catalyst production example, rjf,
and butene-1 were charged to start polymerization. 122 butene-1? Polymerization was carried out for 3 hours while feeding at a constant rate to obtain 3-methylbutene-7 to butene-1 random copolymer powder ♂0≠2.

The butene-7 content of this polymer is /0. ! The wt% heat of fusion was m/l.

0.r parts of Irganox 1010 were added to the obtained polymer, and the mixture was pelletized using an extruder at 320°C. The melting point of this material is 27jt℃, and the melt index is ll-
It was 0Of/10 minutes. Pressure 6QO from this pellet
Polymerization was carried out in the same manner as in Resin Production Example 1 except that the type of comonomer and the amount of feed were changed. A polymer was obtained.

To this, o and r parts of Irganox TOIO were added and pelletized in the same manner as in Resin Production Example-7 to obtain a 100μ sheet. Table 1 shows the physical properties of the obtained resin.

Table 1 Example-l The sheet with a thickness of 100 μm obtained in Resin Production Example-7 was vacuum-pressure formed using a vacuum-pressure forming machine manufactured by Asano Laboratory.

The temperature of both the upper and lower heaters was 100°C. When the surface temperature of the resin reached 20° C. due to heating, the heater was moved under automatic control, the mold was set in its place, and vacuum-pressure molding was performed.

The mold temperature was set at /90°C, and the holding time was 5 seconds. After 5 seconds, the mold opens and compressed air blows out from below.
The molded resin was removed from the mold. The mold releasability was good.

After trimming the obtained molded product, a heat resistance test and an impact resistance test were conducted. For heat resistance testing, molded products were tested at 20
Place in each gear oven at 0℃, 2 J O'C, lj
After a few minutes, the molded product was taken out and the deformed appearance of the molded product was observed. No deformation was observed at any temperature.

Falling weight impact strength at 30°C/-20°C is approximately 4 to o
62 #m tm/cm, / /J each in am
It was 0.cm/cm. The physical property evaluation results are summarized in Table 2.

Example 2 The sheet having a thickness of 100 μm obtained in Resin Production Example 1 was molded in the same manner as in Example 2.

However, the mold holding time was 10 seconds.

Example 3 The resin obtained in Resin Production Example 3 was molded. Table 2 shows the resin surface temperature, mold temperature, mold holding time, appearance test with gear open, and measured impact strength.

Comparative Example-1 A commercially available C-PET container (Pet Kutsuka manufactured by Rispack ■) was placed in gear open at 200°C, 230°C, and -0°C for tS minutes, and after heating, it was taken out and the appearance was observed. 20
There was no change in appearance for 0°C and 2JO'C, but deformation due to heat shrinkage was observed for 2ψO°C.

The results are shown in Table 2.

Comparative Example-2 The impact strength of a commercially available C-PET container (manufactured by Rispack ■, Pet Kutsuka) was measured at 30°C/-20°C. In particular, the impact strength at -2c°C was as low as ≠cm/tM. The results are shown in Table 2.

Comparative Example 3 The resin obtained in Resin Production Example μ was molded. Although the conditions were as shown in Table 2, the molded product was damaged and a normal product could not be obtained.

Comparative example - ≠ Resin production example -! The resin obtained was molded. A SOO μm sheet made from this resin was molded at a temperature of 27
Molding was carried out at 5°C, mold temperature t6o°C, and holding time 5 seconds.

When the molded product was left for 15 minutes in an open gear at 200°C, deformation occurred.

The impact strength at 30°C was as low as λs 4cm/cm.

Regarding the molded products of Example-μ, Comparative Example-Y, and Example-2, salad oil was added to /0
It was heated in a microwave oven using the power of zoow. (Example-4c) A commercially available C-PET container of a similar shape (Lispack ■ Co., Ltd.)
(made by Bettkutska), also add salad oil / 0
0 cc was added and heated in the same manner. (Comparative example-j
) Figure 1 shows the relationship between heating time and salad oil temperature.

As is clear from the figure, the container made of poly3-methylbutene-7 resin according to the present invention has higher efficiency in the use of high frequency waves than the container made of C-PET, and the contents can be heated better.

〔Effect of the invention〕

The top-opening container made of poly3-methylbutene-7 resin according to the present invention has high heat resistance as a container that can be used in both ovens and microwaves.

Can withstand use at high temperatures of ℃, even λOO℃ or higher, 2≠
It can be used even at 0°C.

In addition, when heating in a microwave oven, compared to C-PR and R type containers, there is less absorption or reflection of high frequencies, so the heating efficiency of the food inside the container is better, and the temperature of the food rises in a short time. , or can increase the temperature of food with less power consumption.

Furthermore, most foods that are cooked in a microwave oven, open oven, etc. are frozen, stored, and transported in a container, and the poly-3-methylbutene-7 resin container of the present invention Compared to containers made of C-PET, C-PET has a much higher impact resistance at freezing temperatures, so it has the great advantage of being less likely to be damaged during frozen storage.

Furthermore, on the molding surface, crystallization is fast and release from the mold is good, so it is possible to shorten the molding cycle and mold containers with high production efficiency.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between heating time and salad oil temperature based on Example-Hiroshi and Comparative Example-j. In the figure, 1 indicates the results obtained using Example 11"J-'s, that is, a container made of poly3-methylbutene-7 resin according to the present invention. 2 in the figure indicates the results obtained using Comparative Example-51, that is, a commercially available C-PET container. The results are shown below.

Claims (4)

[Claims] (1) 3-methylbutene-1 and other α having 2 to 20 carbon atoms
- A top-opening container made of poly-3-methylbutene-1 resin, which is formed by forming a random copolymer of olefin and having a heat of fusion of 8 to 14 cal/g into a sheet, and then thermoforming it. (2) The container according to claim 1, wherein the container has a wall thickness of 100 μm to 2 mm. (3) The container according to claim 1, wherein the poly-3-methylbutene-1 resin has a melt index of 0.1 to 100 g/10 minutes. (4) The container according to claim 1, which is a heat-resistant container that does not undergo deformation at a temperature of 160° C. and has a falling weight impact strength of 50 kg·cm/cm or more at room temperature.