JPS631326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [] BACKGROUND TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing a soft to semi-hard thermoplastic propylene block copolymer having excellent heat resistance and impact resistance. In recent years, soft or flexible materials with excellent heat resistance (particularly shape retention against external forces at high temperatures) and impact resistance, especially impact resistance at low temperatures, have been used for automobile parts, home appliance parts, electrical cable covering materials, pipes, containers, etc. Expectations for semi-rigid thermoplastic materials are increasing. Soft materials include polyvinyl chloride with plasticizer and ethylene.
There are vinyl acetate copolymers, ethylene-α-olefin copolymers, etc., which have excellent impact resistance at low temperatures but are inferior in heat deformation resistance. Random copolymers of propylene and other olefins can generally be made into soft materials with superior heat deformation resistance, and they also have excellent impact resistance at room temperature, but they are less susceptible to impact at low temperatures. It is weak. Accordingly, the present invention provides a soft to semi-hard thermoplastic resin material that has an excellent balance of heat resistance and impact resistance not found in conventional materials. Prior Art Many attempts have been made to improve the impact resistance of propylene polymer materials. For example, a random copolymer of propylene and ethylene (Tokuko Sho
42-22052, 46-42988, etc.), and block copolymers (Japanese Patent Publications No. 38-14834, 38-
Publications No. 21494, No. 39-1836, No. 42-22688,
U.S. Patent No. 3624184, British Patent No. 889230, British Patent No. 957777, British Patent No. 1134660, etc.), random copolymer of propylene and butene-1 (U.S. Patent No. 2918457, British Patent No. 3278504, 3332921 specifications, JP-A-50-38787, JP-A-53-79984, etc.), random copolymers of propylene and hexene-1 (JP-A-49-53983, etc.), propylene A typical example is a random copolymer of and 4-methylpentene-1 (JP-A-53-104686, etc.). These prior art techniques have been successful in obtaining propylene-based copolymers with improved impact resistance to a greater or lesser extent, but all of them are hard or semi-hard materials, or even if they are soft, they do not have low-temperature impact resistance. Those that have not been sufficiently improved or have poor heat resistance,
This did not satisfy all the requirements aimed at by the present invention. In addition, the present inventors had previously proposed a block copolymer consisting of propylene and a _C5-12 linear α-olefin as a propylene-based soft thermoplastic resin material with excellent heat resistance and transparency. Gansho 54-
No. 68532), although it was confirmed that this product had a considerable improvement effect in terms of impact resistance, it was still not able to fully meet the demand for high impact resistance. [] Summary of the invention Contrary to the above knowledge, (a) propylene and
A block copolymer containing a random copolymerized portion of _C5-12 linear α-olefin and a homopolymerized portion of (b)ethylene can be produced by selecting copolymerization conditions.
The present inventors have discovered that the material has an excellent balance of heat resistance and impact resistance (particularly impact resistance at low temperatures) in the range from soft to semi-hard. That is, such a copolymer is
It has been found that it has sufficient impact resistance to withstand use not only at temperatures above room temperature, but also at low temperatures of -20℃ and even below -40℃, and has high heat resistance of 120℃, especially 140℃ and above. Ta. Therefore, the method for producing a propylene block copolymer according to the present invention involves carrying out the following steps (a) and (b) stepwise in the presence of a stereoregular polymerization catalyst in decalin at 135°C. The intrinsic viscosity at is 0.3~
The present invention is characterized in that a propylene block copolymer having a yield of 15 dl/g is obtained. (b) Copolymerize propylene and _C5-12 linear α-olefin to produce a random copolymer containing 3-18% by weight of _C5-12 linear α-olefin.
(b) A step of polymerizing ethylene to produce 2 to 40 parts by weight of an ethylene homopolymer. [] Detailed Description of the Invention 1 Block Copolymer - Essential Properties (1) Composition The propylene block copolymer produced by the present invention consists of (a) propylene and a C _5-12 linear α- Contains a random copolymer part with olefin and a homopolymer part of (b)ethylene. The block copolymer according to the present invention does not necessarily consist only of the blocks (a) and (b), but even if other blocks coexist, the total weight of the blocks (a) and (b) is 50% by weight. In particular, it should account for 80% by weight or more. Block (a) refers to a portion produced by polymerization under conditions where propylene and the linear α-olefin are present simultaneously. Block (b) refers to a portion produced by polymerization of ethylene in the absence of the linear α-olefin. Either (a) or (b) may be formed first, but in that case, the portion formed later is formed in the coexistence of the portion formed first. Usually, they are formed in the order of (b) and (b). (stomach),
It is not excluded that other polymer moieties may be formed and present before, after, or during the formation of (b). For example, when a propylene homopolymer portion is formed and present prior to (a) and (b), the resulting copolymer is particularly practical. Also, copolymers (a) and (b)
When formed in the order of (b), a small amount of the propylene and/or the linear α-olefin used in the formation of (a) remains at the beginning of the formation of (b) and is incorporated into (b). However, this is acceptable. In short, both (a) and (b) may be substantially a copolymer of propylene and the linear α-olefin and a homopolymer of ethylene, respectively. Such block copolymers include those in which a homopolymer portion and a random copolymer portion coexist in one polymer molecular chain, physical mixtures of both molecular chains,
Or it could be a mixture of these. The block copolymer of the present invention comprises (a) propylene and
60 to 98 parts by weight, preferably 70 to 95 parts by weight of a random copolymer with C _{5 to 12} linear α-olefin;
(b) Contains a homopolymerized portion of ethylene, 2 to 40 parts by weight, preferably 5 to 30 parts by weight. Random copolymerization part
If (a) exceeds the upper limit of the above range, the effect of improving impact resistance will not be sufficiently exhibited. The content of the linear α-olefin in the random copolymerization portion (a) is approximately 3 to 18% by weight, preferably 5 to 15% by weight. By varying the linear α-olefin content within this range, the rigidity of the block copolymer can be greatly controlled. In particular, if the linear α-olefin content is 10% or more, the material becomes very soft, and if it is less than that, it becomes semi-hard. Furthermore, outside the upper and lower limits of the above range, the heat resistance and impact resistance decrease, respectively. The polymer portion (b) is a homopolymerized portion of ethylene. (2) _C5-12 linear α-olefins α-olefins that fall into this category include 1-pentene, 1-hexene, 1-heptene, and 1-octene.
1, nonene-1, decene-1, undecene-1 and dodecene-1. Among these, pentene-1, hexene-1 and octene-1 are preferred from the viewpoint of reactivity with propylene. Particularly preferred is hexene-1. (3) Molecular weight The molecular weight of the block copolymer is
It is necessary that the intrinsic viscosity at 135°C falls within a range corresponding to 0.3 to 15 dl/g. 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. It is desirable that the melt flow rate (MFR) (based on JIS K 6758) is about 0.1 to 200. 2. Block copolymers - heat resistance and impact resistance The heat resistance of the block copolymers according to the invention is unique in its balance with softness. That is, low-density polyethylene, ethylene-vinyl acetate copolymer, plasticizer-containing polyvinyl chloride, etc., which have the same kind of softness as the present invention, have a deformation rate under heat and pressure of about 100°C to at most 120°C.
In contrast, the block copolymer of the present invention deforms under pressure at a temperature of 130°C or higher.
Furthermore, it was found that there was almost no deformation even at temperatures above 140°C. This may be related to the fact that the melting peak temperature measured by DSC (differential scanning calorimeter) is 140°C or higher. Furthermore, when examining the morphology of a pressed sheet formed from the block copolymer of the present invention using an electron microscope, a sea-island structure is observed, but it was found that the island portions were mainly composed of an ethylene homopolymer. It is clear that this part helps improve impact resistance, especially impact resistance at low temperatures. However, although the conventionally known block copolymers of propylene and ethylene have a similar morphology, the copolymer of the present invention has far superior impact resistance simply because it has a sea-island structure. It is easy to imagine that this is largely due to the chemical structure of the polymers that make up both the ocean and the islands, but the true reason for this improvement in impact resistance is still unclear. isn't it. 3. Production of block copolymer The block copolymer of the present invention is produced by combining (a) propylene with a _C5-12 linear α-
(b) producing 60 to 98 parts by weight, preferably 70 to 95 parts by weight, of a random copolymer with olefin;
It can be produced by combining with a step of producing 2 to 40 parts by weight, preferably 5 to 30 parts by weight, of a homopolymer of ethylene. Steps (a) and (b) may be carried out first, and other polymerization steps (for example, propylene homopolymerization step) may occur before, during, or after steps (a) and (b). In addition, in the transition from step (a) to (b), the propylene used in step (a) and/or the linear α
- A small amount of olefin may remain in the system at the beginning of step (b), but this is acceptable; (a), (b)
The polymerization ratio of each comonomer in the block copolymer is as described in the section regarding the composition of the block copolymer. Suitable stereoregular polymerization catalysts for use in the copolymerization of the present invention include, for example, those mainly containing a titanium component and an organoaluminum compound. As the titanium component, α, β, γ, or δ type titanium trichloride, a titanium compound supported on a carrier such as magnesium chloride, and the like are used. In particular, titanium trichloride containing aluminum chloride (considered to be a eutectic composite of titanium trichloride and aluminum chloride) obtained by reducing titanium tetrachloride using an organoaluminum compound is converted into aluminum chloride using a complexing agent. Titanium trichloride, which is obtained by extracting and removing titanium, is the most suitable. When such titanium trichloride is used as the titanium component of the catalyst, the reactivity of the linear α-olefin in the random copolymerization of propylene and the linear α-olefin is lower than when other titanium components are used. becomes higher. Furthermore, when the bulk density of the polymer powder produced is high and the polymerization is carried out in an inert hydrocarbon medium, the amount of product soluble in the medium can be kept to a significantly low level. If you want to obtain a high yield of copolymer with respect to catalyst,
Titanium trichloride or titanium tetrachloride supported on magnesium chloride or the like can also be used. As an organic aluminum compound component, the general formula
It is preferable to use a compound represented by AlR _a Y _3-a .
a is any number of 0<a3, Y is a halogen atom,
R is a hydrocarbon residue having about 1 to 18 carbon atoms,
Preferred are alkyl groups and aryl groups. Specifically, triethylaluminum, diethylaluminum chloride and the like are preferred. The catalyst consisting of this combination of two essential components may be combined with a small amount of an electron donor as a third component. In particular, when using a titanium component supported on a carrier such as magnesium chloride, it is rather preferable to add a small amount of electron donor. As the electron donor, organic acid esters, ethers, amines, amides, alcohols, ketones, aldehydes, phenols, etc. are used. For details, please refer to Tokugansho.
Reference may be made to specification No. 53-67446. Polymerization can be carried out either continuously or batchwise. When carried out in a continuous manner, one or more polymerization tanks are used for each of the steps (a) and (b), and the reaction is carried out under steady conditions in each tank. When carrying out the batch method, the next step is carried out after the entire or planned amount of the monomer in each step has reacted, but once the predetermined amount of monomer has reacted,
The next step is carried out after some or all of the unreacted monomers have been removed from the tank.
An example of a typical method of operation is to first carry out the homopolymerization of propylene and then to combine propylene with the linear α
- Random copolymerization with olefin (step (a)) is carried out, most of the propylene is purged out of the polymerization tank, and finally homopolymerization of ethylene (step (b)) is carried out. In the method of the present invention, the polymerization temperature is usually 0 to 200°C,
The polymerization pressure is carried out in the range of 0 to 100 Kg/cm ² (gauge pressure). A slight negative pressure (gauge pressure) is allowed. Furthermore, differences in temperature and pressure between each process are allowed. Hydrogen can be used to control the molecular weight of the copolymer. It is also possible to vary the hydrogen concentration between each step to cause a difference in the molecular weight of the copolymer produced therein. Usually, the polymerization is carried out using n-heptane, n-hexane,
Although suspension polymerization in inert hydrocarbons such as toluene or solution polymerization is often used, solvent-free liquid phase polymerization in liquid propylene or polymerization in propylene or ethylene gas may also be used as appropriate. A combination is also possible. 4 Examples The following examples and comparative examples are only intended to illustrate the invention. Olzen bending stiffness (10° angle) unless otherwise specified
is based on ASTM D-747-70, Charpy impact strength is based on JIS K-7111-1971, and heat-pressure deformation rate and DSC analysis are 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 test piece was placed between pressure plates in a silicone oil bath maintained at a constant temperature, and a predetermined load (3 kg) was applied to the test piece. The amount of deformation of the test piece over time is determined using a dial gauge, and the heating and pressing 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 190°C for 3 minutes in 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, read the temperature corresponding to the peak(s). Example 1 1 liter of n-heptane was introduced into a 3 liter stainless steel polymerization vessel equipped with a stirring blade, and after sufficient nitrogen substitution, 0.75 g of diethylaluminium chloride (DEAC) and titanium trichloride (manufactured by Marubeni Solvay Chemical Co., Ltd.) were introduced. (TAU catalyst) 0.15g was added. The temperature of the polymerization vessel
At 50℃, in the first stage of polymerization, ethylene was added at 40g/
2 hours over a period of 2 hours. After the supply of ethylene was stopped, polymerization was continued until the pressure inside the vessel reached a gauge pressure of 0.4 Kg/cm ² (the above is homopolymerization of ethylene). Then, in the second stage of polymerization, the temperature inside the vessel was raised to 60°C, and propylene, hexene-1, and hydrogen were added at 100 g/hour, 165 g/hour, and 500 c.c., respectively.
(STP)/hour over 2.5 hours.
At this point, the supply of hexene-1 and hydrogen was stopped, and only propylene was continuously supplied at a rate of 100 g/hour over 0.5 hour. After stopping the propylene supply,
Copolymerization was continued for another 1.5 hours using only propylene and hexene-1 remaining in the system (propylene/hexene-1 random (copolymerization part)). As described above, a series of copolymerizations spanning two stages was carried out. After that, the catalyst was decomposed with butanol, and the particles of the produced polymer were separated, washed repeatedly with n-heptane, and then dried under reduced pressure at 90°C overnight.Ratio and composition of each polymer part of the obtained copolymer and the physical properties are shown in Table 1. However, since it is difficult to calculate the proportion and composition of each polymer part from this experiment alone, we carried out separate experiments up to the intermediate polymerization stage under the same conditions as in the above example. Immediately, the catalyst was decomposed, washed, separated, and dried under the same conditions as in the example, and the weight and composition of the resulting polymer were measured, assuming that these also applied to each polymerization step in the example. In addition, the composition was measured by carbon 13 NMR. Example 2 The same procedure was carried out except that the feed rate of hexene-1 in the propylene/hexene-1 random copolymerization part was 70 g/hour. Propylene block copolymerization was carried out under the same conditions as in Example 1. The results are shown in Table 1. Example 3 In the propylene/hexene-1 random copolymerization section, propylene, hexene-1, and hydrogen were each supplied at 90 g/hour. , 150g/hour and 800c.c.
Example 1, except that the hexene-1 and hydrogen feeds were stopped at a rate of (STP)/h for 2 hours, and only propylene was continued to be fed at a rate of 90 g/h for 1 hour. Propylene block copolymerization was carried out under the same conditions as described above. The results are shown in Table 1. Example 4 The ethylene supply rate in the ethylene homopolymerization section was 70 g/hour, and the propylene/hexene-1
The hydrogen supply rate in the random copolymerization part was set to 1000
Propylene block copolymerization was carried out under the same conditions as in Example 1 except that cc(STP)/hour was used. The results are shown in Table 1. Comparative Example 1 A propylene/hexene-1 random copolymerization section was carried out directly without carrying out an ethylene homopolymerization section, and at this time, the supply rates of hexene-1 and hydrogen were adjusted respectively.
Propylene copolymerization was carried out under the same conditions as in Example 1 except that the amount was 155 g/hour and 120 c.c. (STP)/hour. The results are shown in Table 1. Comparative Example 2 A propylene/hexene-1 random copolymerization section was carried out directly without carrying out an ethylene homopolymerization section, and at this time, the supply rates of hexene-1 and hydrogen were adjusted respectively.
Propylene copolymerization was carried out under the same conditions as in Example 2 except that the amount was 65 g/hour and 120 c.c. (STP)/hour. The results are shown in Table 1. Comparative Example 3 A propylene/hexene-1 random copolymerization section was directly carried out without carrying out an ethylene homopolymerization section, and at that time, the supply rates of hexene-1 and hydrogen were adjusted respectively.
Propylene block copolymerization was carried out under the same conditions as in Example 3 except that the amount was 85 g/hour and 120 c.c. (STP)/hour. The results are shown in Table 1. Example 5 200g/octene-1 instead of hexene-1
Propylene block copolymerization was carried out under the same conditions as in Example 3, except that the propylene was fed at a rate of The results are shown in Table 1. Example 6 Propylene block copolymerization was carried out under the same conditions as in Example 1 except that decene-1 was used instead of hexene-1. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. The following steps in the presence of a stereoregular polymerization catalyst:
By carrying out (a) and (b) step by step, in decalin,
1. A method for producing a propylene block copolymer, which comprises obtaining a propylene block copolymer having an intrinsic viscosity of 0.3 to 15 dl/g at 135°C. (b) Copolymerize propylene and _C5-12 linear α-olefin to produce a random copolymer containing 3-18% by weight of _C5-12 linear α-olefin.
(b) A step of polymerizing ethylene to produce 2 to 40 parts by weight of an ethylene homopolymer.