JPH0813504B2 - Upper open container made of poly-3-methylbutene-1 resin - Google Patents

Description

The present invention relates to a heat-resistant container made of poly-3-methylbutene-1 resin. More specifically, a rubbery α-olefin copolymer-containing poly3 that can withstand heating in a microwave oven and use in an oven at 160 ° C or higher, preferably 200 ° C or higher.
-A heat-resistant upper opening container made of methylbutene-1 resin.

In recent years, the demand for instant foods for the purpose of shortening the cooking time or simplifying the cooking is increasing with the increase in the number of households where the couple live together or the number of people living alone. With such a tendency and the recent widespread use of microwave ovens, heat-resistant containers used for both microwave ovens and ovens have been attracting attention.

[Conventional technology]

Conventionally, expanded polystyrene is often used as a container for instant foods, but polystyrene has a low softening temperature and its heat resistance is insufficient for use in microwave ovens, ovens and the like.

Polypropylene is a resin having higher heat resistance than polystyrene. A polypropylene resin container usually has sufficient heat resistance when it is heated in a microwave oven with food containing a lot of water.
It cannot be used in the oven above.

On the other hand, a so-called easily crystallizable polyethylene terephthalate (hereinafter referred to as C, in which an additive for accelerating the crystallization rate is added and a polyolefin or the like is blended for enhancing impact resistance).
-PET) thin-walled container also has oil resistance and is being used as a container that can be used in both microwave oven and oven.

[Problems to be Solved by the Present Invention]

However, such a polyethylene terephthalate container has the following disadvantages.

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

Also regarding the heat resistance, the C-PET container is 220 ° C to 230 ° C.
Although it is said that the container can withstand use at ℃, when a C-PET container is actually applied to a household microwave oven, it is easily deformed at high temperatures and cannot be put to practical use. In addition, after heating and crystallization, crystallization progresses and impact resistance is greatly reduced. Further, when the C-PET container is heated at the same output as compared with the glass container, the temperature rise of the contents is slow, that is, the high frequency utilization efficiency is low.

[Means for solving the problem]

In view of the current state of heat-resistant containers such as those mentioned above, the inventors of the present invention have made extensive studies on the application of poly-3-methylbutene-1, which is a high-melting point, highly crystalline polyolefin, to the heat-resistant containers. The present invention has been accomplished by finding that a heat-resistant container having good performance in which the drawbacks of the heat-resistant container made of another resin are improved can be obtained.

That is, the present invention is an upper opening type container made of poly-3-methylbutene-1 resin, which is obtained by forming a sheet of 3-methylbutene-1 to α-olefin random copolymer having a heat of fusion of 8 to 14 cal / g and then thermoforming it. Exist in.

 Hereinafter, the present invention will be described in detail.

The poly-3-methylbutene-1 resin used in the present invention is a random copolymer of 3-methylbutene and another α-olefin having 2 to 20 carbon atoms. Examples of such α-olefins include ethylene, propylene butene-1, hexene-1, octene-1, decene-1, dodecene-1, hexadecene-1, octadecene-1 and the like.
-Olefins are preferred.

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

Other α-olefins other than 3-methylbutene-1 are 2
Random copolymerization of one or more species may be carried out.

In addition, 3-methylbutene-1 was added during the polymerization reaction.
It is also possible to change the concentration of the other α-olefin with respect to the above to obtain a mixed composition of two types of random copolymers having different composition ratios.

There are no particular restrictions on the transition metal compound that is a catalyst and the organometallic compound of a metal of Groups 1 to 3 of the Periodic Table, and those that are commonly used in the polymerization of olefins are used. Preferred is a combination of a solid catalyst component containing an electron-donating compound such as Mg, Ti, halogen and ether or ester, and an organoaluminum compound, and if necessary, an electron-donating compound such as ether or ester. Such solid catalyst components are disclosed in JP-A Nos. 52-98076 and 53-53.
No. -24378, No. 53-85877, No. 53-117083, No. 59-6204, No. 59-11306. Further, the aluminum content is 0.15 or less in the atomic ratio of aluminum to titanium, and a solid titanium trichloride catalyst component containing a complexing agent and an organic aluminum compound, especially aluminum dialkyl monohalide and optionally an ether, an ester, etc. Combinations with electron donating compounds such as Such a solid titanium trichloride catalyst component is disclosed in Japanese Examined Patent Publication No. 55-8451.
55-8452 publication, 55-58003 publication, 54-27871 publication, 55-39165 publication, 55-14054 publication, 53-44.
958, etc.

The polymerization temperature is 0 to 150 ° C. If necessary, a molecular weight modifier such as hydrogen may be used.

The heat of fusion of the copolymer of 3-methylbutene-1 and another α-olefin having 2 to 20 carbon atoms used in the present invention is 8 to cal / g to 14 cal / g as measured by a scanning differential calorimeter (DSC),
It is preferably 9 cal / g to 12 cal / g. The melting point is 250
~ 300 ° C, preferably 260 ° C to 295 ° C. When the melting point is higher than the upper limit, the molding temperature is too high and the polymer is likely to deteriorate during molding. If it is below the lower limit, the heat resistance is insufficient.

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

On the other hand, a polymer having a heat of fusion higher than the above range has excessively high crystallinity and has poor moldability in sheet molding and thermoforming.
The correct shape of molded product cannot be obtained.

32 of the poly-3-methylbutene-1 resin composition of the present invention
The melt index measured according to ASTM D / 238 at 0 ° C. is 0.1 to 100 g / 10 minutes, preferably 0.5.
~ 70g / 10min. When the melt index is higher than the upper limit, the fluidity is good and the sheet moldability is good,
On the other hand, there is drawdown of the sheet during thermoforming, and the formability in thermoforming is reduced. In addition, impact resistance is also reduced.

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

Since the melt index of the poly-3-methylbutene-1 resin composition may change during molding, it is preferable that the melt index of the molded product be within the above range in order to obtain good physical property values.

Since the container of the present invention is used at a high temperature, it is important to select a heat stabilizer, and it is particularly preferable that the container has less scattering at a high temperature.

An example of such an additive is Irganox 1010
(Product name; made by Nippon Ciba Geigy) and Irgafoss P
-A combination of EPQ (trade name; manufactured by Nippon Ciba Geigy),
Irganox 1010, MARKAO-412S (trade name; made by ADEKA ARGUS) and, in some cases, Irgafoss P-EP
Combination of Q, MARKAO-18 (product name; made by ADEKA ARGUS), MARKAO-412S (product name; made by ADEKA ARGUS)
In some cases, a combination of Ingafoss P-EPQ or the like is used. Rasmit HPM-12 (trade name;
Dai-ichi Kogyo Seiyaku), Ingafos 168 (trade name; manufactured by Nippon Ciba Geigy), DSTDP, etc. are also effective.

As the antioxidant used in the present invention, particularly in containers used at high temperatures of 200 ° C. or higher, only the hindered phenolic antioxidant is used in order to avoid generation of odor and discoloration of the material. It is necessary to use a hindered phenolic compound which satisfies the requirement that the 1.0% by weight reduction temperature measured by) is 290 ° C or higher.

The 1.0 wt% reduction temperature measured by TGA here means the weight reduction of 1.0 wt% when the weight loss was measured at a temperature rising rate of 15 ° C / min under an air flow rate of 100 ml / min. Is the temperature of.

Examples of the special hindered phenolic antioxidant used in the composition of the present invention include, for example, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. And 3,9
-Bis [1,1-dimethyl-2- {β- (3-t-butyl-4-hydroxy-5-methylphenyl) propynyloxy} ethyl] -2,4,8,10-tetraoxysuspyro [5 ,
5] It is desirable to use undecane alone or in combination.

The amount of antioxidant added is 3-methylbutene-1 homopolymer or 3-methylbutene-1 and other α-containing 2 to 20 carbon atoms.
The amount is 0.1 to 3 parts by weight, preferably 0.2 to 2 parts by weight, based on 100 parts by weight of the copolymer with olefin. If the amount is less than 0.1 parts by weight, sufficient effect cannot be obtained, and even if it is used in excess of 3 parts by weight, the effect is not improved and it is economically disadvantageous. 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, a thermoforming method is preferably used. The thermoforming method is "Practical plastic terminology dictionary" (edited by Shoji Seto, Plastics Age, 1975) or on-site manual "Thermoforming (vacuum forming, pressure forming).
Hen "(edited by Sogo Kagaku Kenkyusho, edited by Asano Research Institute Co., Ltd., Kazuo Asano), etc., is a method of processing a sheet of thermoplastic resin, with the heat-softened sheet being deformed by some external force. It is a method of cooling and making molded products, such as ridge molding, matched molding, straight molding (vacuum, pressure molding), drape molding, reverse draw molding,
Examples include air slip molding, Prada assist molding, Prada assist reverse draw molding, contact heating and pressure molding. Usually, a vacuum-assisted vacuum or pressure-assisted molding with a plug assist can sufficiently obtain a molded product of a desired shape.

To describe the outline of vacuum and pressure molding, a sheet of the above-mentioned poly-3-methylbutene-1 resin composition is molded, and then the sheet is softened by heating, and by vacuum and / or pressure molding,
The softened sheet is uniformly spread and stretched in a mold. Then, after the crystallization is sufficiently advanced in the mold, the molded product is taken out from the mold. The sheet can be formed by a usual method such as T-die extrusion. The thickness of the sheet is usually 200 μm to 2.5 mm, preferably 300 μm to 1.5
mm. If the thickness of the sheet exceeds this value, it becomes difficult to uniformly heat the sheet, and the progress of crystallization in each part of the sheet becomes uneven, which is not preferable.

The heating temperature of the sheet is 220 to 310 ° C, preferably 250 to 3
Although it is 00 ° C., the range of ± 20 ° C. of the melting point of the resin composition is preferable, and normally the melting point of −5 to + 10 ° C. is optimum.

Next, when the sheet becomes translucent due to heating, it is desirable to form by applying vacuum or air pressure. If the heating time is long or the heating temperature is too high, the resin deteriorates and the physical properties deteriorate. It is not preferable. The heating time is usually 30 seconds or less.

Although the mold differs depending on the type of resin, the temperature is set between 100 and 250 ℃, preferably between 150 and 220 ℃, the resin is sufficiently crystallized, and the residual stress is limited to a minimum Taken out of the mold. Molded container has a wall thickness of 100 μm to 2 m
m, preferably 200 μm to 1 mm. If the molding temperature is too low, molding stress remains and the heat distortion temperature decreases, which is a practical problem.

Since the poly-3-methylbutene-1 resin composition of the present invention is rapidly crystallized, the mold holding time may be short, and 2 seconds or more, usually 5 seconds or less is sufficient. Therefore, it is possible to mold in a very short cycle. Further, since the poly-3-methylbutene-1 resin of the present invention has a good mold releasability, it has an advantage that it can be easily taken out from the mold after molding and the defective rate is small. Regarding cooling of the container after removing it from the mold,
If necessary, a cooling mold can be used.

The container used as a molded product in the present invention is an upper opening type container. The above-mentioned open-type container means a container having an open upper part and having a self-shape-retaining property, such as a tray-shaped, dish-shaped, cup-shaped, box-shaped, or container provided with a partition. For example, a soft container such as a bag is not referred to as an upper opening type container in the present invention.

The container made of the poly-3-methylbutene-1 resin composition of the present invention molded as described above has high heat resistance, and even if it is held at an ambient temperature of 160 ° C. which causes deformation in polypropylene, twisting, warping, etc. No deformation, no yellowing problem.
Furthermore, by selecting appropriate resin and molding conditions, problems such as deformation and discoloration do not occur even under conditions of 200 ° C or higher, and 240 ° C
Has heat resistance up to.

Further, compared to C-PET, there is no reduction in impact strength after heating, and in this sense it can be said that the heat resistance is high. The impact strength at room temperature is 50 kg · cm / cm or more, preferably 125 kg · cm / cm or more.

The room temperature here means 20 to 40 ° C. Also, the impact strength is particularly high at low temperatures, and the falling weight impact strength at -20 ° C is
There is more than 10kgcm / cm. Further, the difference in impact strength between 30 ° C. and −20 ° C. is 1/20 or less in the commercially available C-PET product, whereas it is about 1/2 to 1/5 in the container of the present invention. It is characterized by a small decrease from impact strength at room temperature.

〔Example〕

Examples will be shown below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

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

The melt index (MI) is ASTM D1238 (320
C., 2.16 kg load).

The melting point and heat of fusion of the copolymer were determined by measuring with a Dupont 9900 type differential scanning calorimeter (DSC). The melting curve was measured by once raising the temperature at 16 ° C / min for the sample that was once melted at 335 ° C for 10 minutes in the DSC device and then gradually cooled at 16 ° C / min.

The peak top was adopted as the melting point. When two or more peak tops were shown, each was regarded as a melting point. The heat of fusion was calculated from the area enclosed by the tangent line to the melting curve, in principle by drawing a tangent line to the peak field.

The content of each component of the copolymer was determined by measuring a ¹³ ° C. high resolution NMR spectrum at 310 ° C. using a JEOL FX200 type NMR device (equipped with a high temperature temperature variable device).

Vacuum and pressure molding were performed using a true pressure molding machine (with plug assist) manufactured by Asano Laboratory Co., Ltd. The molding conditions such as molding temperature and mold temperature are shown in Table 2 together with the results of physical property evaluation. In addition, about the resin composition which has two or more melting | fusing points, the average value was calculated | required and the molding temperature was determined based on the value.

The shape of the mold is a rectangular container with a size of 15 cm x 12.5 cm x depth 2.5 cm.

Measurement of heat resistance (oven test) The molded product was placed in a gear oven set to 200 ° C, 230 ° C, 240 ° C, and 250 ° C, and after 15 minutes, taken out to confirm the appearance. (Gear Oven is Tabai Gear Oven GPS
-112 type was used. ) Measurement of content heating rate by microwave oven 100 cc of salad oil was placed in a molded mold, and the internal temperature was measured with time to measure the ease of heating the content.
(The microwave oven used was a Mitsubishi Electric RO-1900 type microwave oven.

The sample of the poly-3-methylbutene-1 resin composition used for the falling weight impact strength measurement was measured as it was for a heat treatment at 200 ° C. for 1 hr after molding, and for a commercially available C-PET container. did. The measuring device is a drop tester manufactured by Rheometrics Co., the height of the falling weight is 50.292 cm, and the weight of the falling weight is 3.6197.
It was measured at kg and falling velocity 3.33.3 M / S. The measurement temperature is 30 ℃ and -20 ℃.

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

The sample piece was cut out from the bottom of the container, fixed to a clamp having an inner diameter of 1.5 inches, and used for the measurement.

Example of catalyst production At room temperature, 515 ml of purified toluene was put into the autoclave of procedure 1 which was sufficiently replaced with nitrogen, and 65.1 g (0.5 mol) of n-butyl ether and 94.9 g (0.5 m of titanium tetrachloride) were added under stirring.
ol) and diethyl aluminum chloride 28.6g (0.24m
ol) was added to give a brown homogeneous solution. Then, the temperature is raised to 30 ° C. After 30 minutes, raise the temperature to 40 ° C and leave for 2 hours
Hold 40 ° C. Then 32 g of titanium tetrachloride (0.17 mol)
And 15.5 g of tridecyl methacrylate (0.058 mol) were added and the temperature was raised to 98 ° C. After holding at 98 ° C for 2 hours, a granular purple solid was separated and washed with toluene to obtain solid titanium trichloride.

Resin Production Example-1 Diethyl aluminum monochloride was placed in an induction-stirring autoclave with a volume of 5 which was sufficiently dried and purged with argon.
9.1 mmol and 3-methylbutene-1 3000 ml were charged.
After the internal temperature was raised to 80 ° C., 2.83 g of the solid titanium trichloride catalyst component obtained in the catalyst production example and butene-1 were charged to start polymerization. Polymerization was carried out for 3 hours while feeding 122 g of butene-1 at a constant ratio to obtain 804 g of 3-methylbutene-1 to butene-1 random copolymer powder.

The butene-1 content of this polymer is 10.5 wt% and the heat of fusion is
It was 9 cal / g.

Add 0.8 parts of Inganox 1010 to the obtained polymer 320
Pelletization was performed by an extruder at ℃. This product had a melting point of 275 ° C. and a melt index of 4.0 g / 10 minutes.
A sheet having a pressure of 600μ was formed from the pellets.

Resin Production Examples 2 to 5 Polymerization was performed in the same manner as in Resin Production Example 1 except that the type of comonomer and the feed amount were changed to obtain 3-methylbutene-1 to α-olefin random copolymers as shown in Table 1.

0.8 part of Irganox 1010 was added to this product and pelletized in the same manner as in Resin Production Example-1 to obtain a sheet of 600 μm.
Table 1 shows the physical properties of the obtained resin.

Example-1 The sheet having a thickness of 600 µm obtained in Resin Production Example-1 was vacuum-pressure formed by a vacuum-pressure forming machine manufactured by Asano Laboratory.

The temperature of the heater was set to 600 ° C for both upper and lower sides. When the surface temperature of the resin reached 290 ° C. by heating, the heater was moved by automatic control, the mold was set instead, and vacuum pressure molding was performed.

The mold temperature was set to 190 ° C. and the holding time was 5 seconds.
After 5 seconds, at the same time when the mold was opened, compressed air spouted from below, and the molded resin was removed from the mold. The releasability was good.

After trimming the obtained molded product, a heat resistance test and an impact resistance test were performed. As a heat resistance test, 20
It was placed in each gear oven at 0 ° C and 230 ° C, taken out after 15 minutes, and the deformed appearance of the molded product was observed. No deformation was observed at each temperature.

The drop weight impact strengths at 30 ° C / -20 ° C were 62 kg · cm / cm and 113 kg · cm / cm, respectively, at a thickness of about 400 μm. The physical property evaluation results are summarized in Table 2.

Example-2 The sheet having a thickness of 600 μm obtained in Resin Production Example-2 was molded in the same manner as in Example-1.

 However, the die holding time was 4 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 by gear oven, and impact strength measured value.

Comparative Example-1 A commercially available C-PET container (Pet Cooker manufactured by Lispack Co., Ltd.) was placed in a gear oven at 200 ° C, 230 ° C and 240 ° C.
It was put in for 5 minutes, heated and taken out to see the appearance. 200 ° C, 230
The appearance did not change at ℃, but at 240 ℃, deformation due to heat shrinkage was observed.

 The results are shown in Table 2.

Comparative Example-2 The impact strength of a commercially available C-PET container (Pet Cooker, manufactured by Lispack Co., Ltd.) was measured at 30 ° C / -20 ° C. In particular, the impact strength at -20 ° C was as low as 4 kg · cm / cm. The results are shown in Table 2.

Comparative Example-3 The resin obtained in Resin Production Example-4 was molded. The conditions were as shown in Table 2, but the molded product was damaged and a normal product could not be obtained.

Comparative Example-4 The resin obtained in Resin Production Example-5 was molded.
A 500 μm sheet made from this resin is molded at a molding temperature of 275
C., mold temperature 160.degree. C., holding time 5 seconds.

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

 The impact strength at 30 ° C was as low as 25 kg · cm / cm.

Example-4, Comparative Example-5 With respect to the molded article of Example-2, 100 cc of salad oil was used.
It was put in and heated by a microwave oven with a power of 500W. (Example-4) A commercially available C-PET container of the same shape (Lispack Co., Ltd.)
100c of salad oil after all)
c) and heated by the same method. (Comparative Example-5) Fig. 1 shows the relationship between the heating time and the temperature of the salad oil.

As is apparent from the figure, the container made of poly-3-methylbutene-1 resin according to the present invention has a higher utilization efficiency of high frequency and a better heating of contents than the container made of C-PET.

[Effects of the Invention] The upper open container made of poly-3-methylbutene-1 resin according to the present invention has high heat resistance as a container that can be used in both an oven and a microwave oven. Withstands use and can be used at 240 ℃.

Further, when heated in a microwave oven, since the absorption or reflection of high frequency is less than that of a container made of C-PET, the food in the container has good heating efficiency and the temperature of the food rises in a short time, or There are advantages such as the food temperature rises with less power consumption.

Further, in most cases, foods cooked in a microwave oven, oven, etc. are frozen, stored and transported in a container, but the container made of the poly-3-methylbutene-1 resin of the present invention is used. Has significantly higher impact resistance at freezing temperature than a C-PET container, and has a very great advantage that the container is less damaged during frozen storage.

Further, on the molding surface, crystallization is fast and the mold releasability from the mold is good, so that it is possible to shorten the molding cycle and mold the container with high production efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between heating time and temperature of salad oil based on Example-4 and Comparative Example-5. In the figure, 1 shows the result of Example-2, that is, the case of using the container made of the poly-3-methylbutene-1 resin according to the present invention. Reference numeral 2 in the figure shows the result when Comparative Example-5, that is, when a commercially available C-PET container was used.

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Claims (4)

[Claims] Claims: 1. A random copolymer comprising 3-methylbutene-1 and another α-olefin having 2 to 20 carbon atoms and having a heat of fusion of 8 to 14 cal / g, which is formed into a sheet and then thermoformed. An upper open container made of 3-methylbutene-1 resin. 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 melt index of the poly-3-methylbutene-1 resin is 0.1 to 100 g / 10 minutes. 4. The container according to claim 1, which is a heat-resistant container which does not deform at a temperature of 160 ° C. and has a falling weight impact strength of 50 kg · cm / cm or more at room temperature. .