JPS638131B2 - - Google Patents

Description

[Detailed description of the invention]

[] Background of the Invention The present invention relates to a method for producing a propylene block copolymer having excellent heat resistance, transparency, and flexibility. In recent years, the rapid development of packaging materials and containers such as synthetic resin films and bottles has been remarkable. Under these circumstances, there is a strong demand for improved heat resistance, especially for transparent and soft materials. Such materials can be used in the pharmaceutical field, such as infusion bags and blood bags, and in the food field, such as squeeze bottles for mayonnaise and ketchup. It goes without saying that it needs to be soft, but it must also have enough heat resistance (shape retention at high temperatures) to withstand sterilization using hot water.
Moreover, it goes without saying that the manufacturing cost of such materials must be reasonable for their intended use. Until now, such soft materials include low-density polyethylene, ethylene-vinyl acetate copolymer,
Soft polyvinyl chloride and other materials have been used, but low-density polyethylene and ethylene-vinyl acetate copolymers have melting points of just over 110°C to around 90°C, and cannot withstand sterilization using hot water as is. Furthermore, low-density polyethylene, which has a relatively high melting point, cannot be said to have very high transparency. Although soft polyvinyl chloride has the heat resistance to withstand sterilization treatment with hot water, problems remain in its use in the pharmaceutical and food fields due to the toxicity of the residual monomers and plasticizers it contains. On the other hand, among propylene-based copolymers, random copolymers of propylene and ethylene or propylene and butene-1 have heat resistance that can withstand hot water sterilization; The degree of softness is still insufficient. This is probably because as the content of ethylene and butene-1 increases, the resulting copolymer initially begins to become soft, but once the proportion of block-like chains of these comonomer units begins to increase, it begins to become hard again. . Furthermore, although the transparency of these copolymers may be better than that of propylene homopolymers, they tend to start to deteriorate again at high comonomer contents, similar to the recuring described above, and as a result, they cannot be used in the various applications mentioned above. It becomes unsuitable for application. A copolymer of propylene and a branched α-olefin such as 4-methylpentene-1 is also preferable in terms of heat resistance, as is a copolymer of ethylene or butene-1; In order to achieve this, such expensive comonomers must be introduced at high concentrations, and even when softened at such high concentrations, the transparency is extremely poor. It is. However, copolymers of propylene and linear α-olefins having 5 to 12 carbon atoms, such as hexene-1, are soft, transparent, and heat-resistant materials even with relatively small comonomer contents. It is known that The present invention independently improves only the heat resistance of the copolymer of propylene and linear α-olefin having 5 to 12 carbon atoms, without significantly reducing its excellent flexibility and transparency. The purpose of the present invention is to provide a method for producing a copolymer that is [] Summary of the Invention In order to achieve the above object, as a result of repeated studies on various copolymerization methods and the physical properties of the copolymers obtained thereby, we carried out homopolymerization of propylene at a specific ratio, and then and carbon number 5
Only when copolymerization with linear α-olefin of -12 is carried out, the resulting block copolymer has an independently improved heat resistance as described above, with almost no loss in transparency and soft properties. It was found that there was no. Therefore, the method for producing a propylene block copolymer defined by the following (1) to (3) according to the present invention involves totally producing propylene in the first stage of polymerization in the presence of a stereoregular polymerization catalyst. Homopolymerization is carried out until the amount corresponds to 1 to 30% by weight of the polymerized amount, and in the second step, propylene and linear α-olefin (A) having 5 to 12 carbon atoms are added.
and 70 to 70% of the total polymerization amount when both are present at the same time.
It is characterized in that it is copolymerized to an amount equivalent to 99% by weight. (1) Propylene homopolymerized portion (a) 1 to 30% by weight, propylene containing 8 to 20% by weight of linear α-olefin units having 5 to 12 carbon atoms, and a random combination of the α-olefin. Polymerization part (b) 99-70% by weight
And to become essential. (2) The intrinsic viscosity is 0.3 to 15 dl/(135℃, in decalin). (3) Olsen bending stiffness (ASTM D-747-70,
10° square) value is 6000Kg/ ^cm2 or less. [] Detailed Description of the Invention 1 Copolymer 1 Composition and Molecular Weight The copolymer produced by the present invention contains (a) a homopolymerized portion of propylene of 1 to 30% by weight, and (b) propylene and a carbon number of 5. ~12 linear α-olefins (A)
It consists of 99-70% by weight of a random copolymerized portion with (details will be described later). When the proportion of the propylene homopolymerized portion is within this range, only the heat resistance can be improved without substantially impairing the soft properties and transparency of the copolymer. Below this range, the effect is not recognized. If the temperature exceeds this range, the heat resistance will still be improved to some extent, but the rigidity will rapidly increase and the transparency will deteriorate. The content of monomer A units in the random copolymerization part is selected from the range of 8 to 20% by weight, preferably 5 to 25% by weight, and most preferably 8 to 20% by weight. Heat resistance, rigidity, and transparency can be achieved in a well-balanced manner only within this range. If the content is less than this range, softness and transparency cannot be said to be sufficient. On the other hand, if it exceeds this range, not only will the heat resistance decrease, but also the surface will become sticky when molded. In addition, the fact that the present invention essentially consists of propylene and monomer A means that in addition to these two monomers,
This means that it may contain small amounts of copolymerizable monomers, for example up to 10% by weight, based on the total amount of both monomers. The molecular weight of the copolymer must fall within a range corresponding to an intrinsic viscosity of 0.5 to 15 dl/g at 135°C in decalin. If it is less than this, the mechanical properties of the copolymer will not reach a practical level, or molding itself will become impossible. If the molecular weight is higher than this, the viscoelastic properties in the molten state deteriorate and molding becomes impossible. In addition, in order for this copolymer to be said to be a soft material, the Olzen bending stiffness value must be 6000 kg/
It is desirable that it be below cm ² , preferably below 5000 Kg/cm ² . 2. Melting properties In order for this copolymer to exhibit sufficient heat resistance, it is desirable that the following requirements be satisfied regarding the melting curve based on DSC (differential scanning calorimetry).
That is, one or more melting peaks are all present at 130°C or higher, preferably 135°C or higher, or the heat of fusion of the portion that melts at a temperature of 130°C or higher is 40% or more of the total heat of fusion, preferably 45°C or higher. % or more. 3 Monomer A Monomer A is a linear α-olefin having 5 to 12 carbon atoms. It is therefore selected from 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene and 1-dodecene. Among these, pentene-1, from the viewpoint of copolymerization reactivity with propylene,
Hexene-1 and octene-1 are preferred.
Further, these monomers may be used alone or as a mixture. 2 Production Method The copolymer of the present invention is produced in the presence of a stereoregular polymerization catalyst. A preferred catalyst is one containing at least a titanium component and an organoaluminum compound. Typical titanium components of the catalyst include various titanium trichlorides of α, β, γ, and δ types, and titanium trichloride and titanium tetrachloride supported on various carriers mainly composed of magnesium chloride. Among them, a complexing agent (for example, isoamyl ether) is selected from a eutectic composite of titanium trichloride and aluminum chloride, which is obtained by reducing titanium tetrachloride using an organoaluminum compound, as described in JP-A No. 47-34478. titanium trichloride compositions obtained by extracting and removing by-product aluminum chloride (activated with dialkyl aluminum halide when used), and titanium trichloride and titanium tetrachloride supported on carriers containing magnesium chloride ( (activated with trialkylaluminum when used) is advantageous due to its high activity. In particular, the use of this complexed/extracted titanium trichloride composition is most advantageous because the resulting copolymer has a good particle morphology and the efficiency of introducing monomer A into the copolymer is high. In addition to these compounds, all compounds known to have olefin polymerization ability, such as various tetra- to divalent titanium halides, alkyl halides, alkoxides, and alkoxy halides, can be used as the titanium component of the present invention. The organoaluminum compound used in combination with the above titanium component has the general formula AlR _n X _3-n (where R is hydrogen or a hydrocarbon residue having about 1 to 12 carbon atoms, and An alkoxy group (1≦m≦3) is typical. Specific examples include triethylaluminum, tri-i-butylaluminum, tri-n-octylaluminum, diethylaluminum hydride, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminium iodide, and the like. It is also possible to improve the activity, stereoregularity, particle properties of the copolymer, etc. by adding various electron-donating compounds to the titanium component and organoaluminum compound. The copolymerization reaction can be carried out either batchwise or continuously. Further, it can be produced by any of suspension polymerization in an inert solvent, solution polymerization, solventless polymerization in liquid phase propylene, and gas phase polymerization in gas phase propylene. In addition, any techniques applicable to the homopolymerization and copolymerization of propylene or α-olefin that do not impair the spirit of the present invention can be used. 3 Experimental Examples In the experimental examples and comparative examples below, unless otherwise specified, the Olzen bending stiffness is ASTM D-747.
-70, the haze was measured in accordance with JIS K-6714-1958, and the heat-pressure deformation rate and DSC analysis were measured based on the following method. Measurement of deformation rate under heat and pressure The copolymer whose heat resistance is to be evaluated is made into a 2 mm thick sheet by pressing or injection molding.
Cut this sheet into test pieces 10 mm long, 10 mm wide, and 2 mm thick. This test piece was heated to the specified temperature (130℃)
The specimen was placed between pressure plates in a silicone oil bath maintained at a constant temperature, and a predetermined load (1 kg) was applied to the specimen. The amount of change in the test piece over time is determined using a dial gauge, and the heat-pressure deformation rate (%) is calculated using the following formula. Heating and pressing deformation rate (%) = Deformation amount of test piece / Thickness of test piece (2 mm) x 10
0 DSC analysis Using a Perkin-Elmer model DSC-2, 5 mg of the copolymer sample was heated and melted at 250°C for 3 minutes under a nitrogen stream, and then cooled to 60°C at a cooling rate of 10°C/min to crystallize. , further obtain a thermogram while melting at a heating rate of 10°C/min. From this, the temperature corresponding to the peak and the ratio of the heat of fusion to the total heat of fusion in a predetermined temperature range are read. Example 1 A 10-liter stainless steel autoclave equipped with a stirrer was sufficiently replaced with propylene, and then replaced with heptane.
3.5 liters, 1.5 g of diethylaluminum chloride (DEAC), and 0.3 g of titanium trichloride (TAU catalyst manufactured by Marubeni Solvay Chemical Co., Ltd.) were added. Temperature 50℃
, propylene is added at a rate of 300 g/hour, and hydrogen is added to
Feed was carried out at a rate of 500 c.c. (STP)/hour for 45 minutes. Thereafter, the temperature was raised to 60 DEG C., and propylene was fed at a rate of 300 g/hour, hexene-1 at 550 g/hour, and hydrogen at a rate of 450 c.c. (STP)/hour for 3 hours. After the copolymerization reaction was completed, the catalyst was decomposed with butanol, and the resulting powdered block copolymer was dried under reduced pressure. Table 1 shows the physical properties of this block copolymer. In addition, since it is not possible to directly calculate the proportion of the propylene homopolymer portion in the block copolymer and the hexene-1 content in the random copolymer portion, apart from the above production experiment of the block copolymer, we conducted This was indirectly determined by assuming that the same amount of propylene homopolymer was produced during block copolymerization as was obtained by conducting a manufacturing experiment. Examples 2 and 3 Propylene homopolymerization times 20 minutes and 10 minutes
A block copolymer was produced under all the same conditions as in Example 1, except that the heating time was increased for 1 minute. Table 1 shows the physical properties of the obtained block copolymer. Comparative Example 1 A random copolymer was produced under the same conditions as in Example 1, except that propylene homopolymerization was not carried out. Table 1 shows the physical properties of the obtained copolymer. Comparative Example 2 Except that the time for propylene homopolymerization was 60 minutes, and the supply rate and time of propylene and hexene-1 in random copolymerization of propylene and hexene-1 were 340 g/hour, 800 Kg/hour, and 60 minutes, respectively. Block copolymerization was carried out under the same conditions as in Example 1. Table 1 shows the physical properties of the obtained copolymer. Examples 4 and 5 The homopolymerization time of propylene was 40 minutes or 15 minutes, and the supply rate of hexene-1 in the random copolymerization section of propylene and hexene-1 was 325 minutes.
A block copolymer was produced under the same conditions as in Example 1, except that the amount was changed to g/hour. Table 1 shows the physical properties of the obtained block copolymer. Comparative Example 3 A random copolymer was produced under the same conditions as in Example 4, except that propylene homopolymerization was not carried out. Table 1 shows the physical properties of the obtained copolymer. Comparative Example 4 The propylene homopolymerization time was 1 hour, and the supply amount and copolymerization time of propylene and hexene-1 in the random copolymerization section of propylene and hexene-1 were 230 g/hour, 350 g/hour, and 60 g/hour, respectively.
A block copolymer was produced under the same conditions as in Example 1, except that the heating time was for a minute. Table 1 shows the physical properties of the obtained copolymer. Comparative Example 5 The propylene homopolymerization time was 15 minutes, the propylene feed rate and time in the random copolymerization of propylene and hexene-1 was 195 g/hour and 90 minutes, and the hexene-1 feed rate and time was 1500 g/hour. A block copolymer was produced under the same conditions as in Example 1, except that the reaction time was 60 minutes. However, the resulting slurry was too viscous to be filtered, so the polymer was recovered by steam stripping. Table 2 shows the physical properties of the obtained block copolymer. Comparative Example 6 A block copolymer was produced under the same conditions as in Example 1, except that the propylene homopolymerization time was 22 minutes and the supply rate of hexene-1 in the random copolymerization of propylene and hexene-1 was 66 g/hour. was manufactured. Table 2 shows the physical properties of the obtained copolymer.

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Claims (1)

[Claims] 1 In the presence of a stereoregular polymerization catalyst, propylene is homopolymerized in the first stage of polymerization to an amount corresponding to 1 to 30% by weight of the total polymerization amount, and in the second stage, propylene is and a straight-chain α-olefin having 5 to 12 carbon atoms in a state where both are present at the same time and the total polymerization amount is 70 to 99.
A method for producing a propylene block copolymer defined by the following (1) to (3), which comprises copolymerizing until the amount corresponds to % by weight. (1) Propylene homopolymerized portion (a) 1 to 30% by weight, propylene containing 8 to 20% by weight of linear α-olefin units having 5 to 12 carbon atoms, and a random combination of the α-olefin. Polymerization part (b) 99-70% by weight
And to become essential. (2) The intrinsic viscosity is 0.3 to 15 dl/(135℃, in decalin). (3) Olsen bending stiffness (ASTM D-747-70,
10° square) value is 6000Kg/ ^cm2 or less.