JP6268720B2 - Propylene-based block copolymer production method - Google Patents

Description

  The present invention relates to a method for producing a propylene-based block copolymer. More specifically, even if it is a soft propylene-based block copolymer that easily exhibits adhesiveness, a copolymer powder having good fluidity is obtained. The present invention relates to a method for producing a propylene-based block copolymer.

Olefin-based thermoplastic elastomers or plastomers have moderate flexibility and strength, are highly adaptable to environmental issues such as recycling and incineration, and are lightweight and excellent in moldability and economy. It is used in a wide range of fields as films, sheets, fibers, non-woven fabrics, various containers, moldability, and modifiers. Here, as the olefin-based thermoplastic elastomer or plastomer, a polymer blend containing a component of a random copolymer represented by a propylene / α-olefin copolymer is well known.
Among such thermoplastic elastomers or plastomers, a crystalline polymer containing polypropylene as a main component is produced in the first step, and a semicrystalline or amorphous elastomer containing a propylene / α-olefin copolymer as a main component in the second step. What is called a soft propylene-based block copolymer obtained by producing the components is superior in heat resistance and productivity compared to a random copolymer elastomer or plastomer, and is produced by mechanical mixing. In recent years, the elastomer or plastomer containing the components of the random copolymer has been widely used because of its high economic efficiency and excellent heat resistance since the production cost can be reduced.

Conventional soft propylene block copolymers have been produced using Ziegler-Natta catalysts. Such a soft propylene-based block copolymer is a polymer powder (hereinafter also referred to as “powder”) due to the presence of an oligomer having a low molecular weight, which is a by-product generated due to non-uniformity of catalytic active sites. Since the components of the second step are bleed on the surface, the fluidity of the powder is poor, and there is a problem that practical continuous production is difficult. In order to improve the fluidity of the powder, the production technology of soft propylene block copolymer with Ziegler-Natta catalyst was devised, and catalyst deactivator was added during the gas phase polymerization technology, propylene / α-olefin copolymerization The production range has been expanded so that a softer propylene-based block copolymer can be produced by a core-shell structure forming technique, a powder particle size-enhancing technique, and the like. In particular, the combination of gas phase polymerization and powder particle size enlargement technology has greatly expanded the production limit of soft propylene block copolymers. Furthermore, by converting to a metallocene catalyst having a uniform catalytic activity point, it is possible to suppress the by-product of the oligomer and to make it softer.
On the other hand, with the conversion from a Ziegler-Natta catalyst to a metallocene catalyst, the reactivity of α-olefins having 4 or more carbon atoms (hereinafter also referred to as “C4”) is enhanced. A propylene-based block copolymer obtained by producing an elastomer component incorporating a larger amount of olefin can be produced. And since this propylene-type block copolymer has favorable softness | flexibility and transparency, the expansion | deployment to various uses is anticipated (for example, refer patent document 1).
However, the soft propylene block copolymer obtained by polymerization of ethylene and / or a random copolymer of C4 to C20 α-olefin and propylene with a metallocene catalyst has reduced oligomer by-product. Regardless, the fluidity of the powder is poor, and it is difficult to apply it to a practical manufacturing plant only by the combination of the above gas phase polymerization, core-shell structure forming technology and powder particle size increasing technology. .

  On the other hand, as a method for producing an adhesive powder, a production method is known in which fine particles are fed to a polymerization vessel and the surface of the adhesive powder is modified to maintain the fluidity of the powder (see, for example, Patent Document 2). . However, even if it is necessary to input a large amount of fine particles, and even if the subsequent production brand is a brand that does not have poor adhesion in continuous production, or a brand that does not want to contain fine particles, it remains in the polymerizer. As a result, the production loss increases, the production cost increases, and the quality of the product remains.

Moreover, the manufacturing method of the alpha-olefin block copolymer which feeds siloxanes or polysiloxanes to a polymerization device, and prevents adhesion is also known (for example, refer patent document 3).
However, in the case of the block copolymer in which the α-olefin content exceeds 5% by weight, it is insufficient as a method for maintaining the powder properties.

JP 2010-168498 A JP-A-6-32811 JP 63-146914 A (JP-B-5-62885)

In the polymerization of a random copolymer of ethylene and / or C4 to C20 α-olefin and propylene described in Patent Document 1, the α-olefin content is 5% by weight or less particularly in the first step. In the second step, the component (B) having an α-olefin content of 15 to 80% by weight is polymerized, and the proportion of the component (B) is 20 to 70% by weight. During polymerization of the copolymer, the amorphous component polymerized in the second step bleeds to the powder surface. As a result, the powder has adhesiveness and agglomeration of the powders occurs. When such agglomeration of powders occurs, a heat spot due to poor stirring is formed in gas phase polymerization, which is a main cause of formation of a lump. At the same time, since powder agglomeration may cause clogging in the extraction pipe from the polymerization vessel, gas phase polymerization has been difficult to apply to production plants.
Further, in the surface modification of the adhesive powder with the fine particles described in Patent Document 2, the present inventors have confirmed that the fine particles are required to be at least 1% by weight or more with respect to the adhesive powder. Yes. The introduction of a large amount of fine particles into the production plant may clog a heat exchanger or the like, and therefore, it is necessary to search for a liquid surface modifier with less scattering to the circulation system of the reactor.
Further, in the method for adding silicone oil described in Patent Document 3, a large amount of amorphous component is coated with silicone under the polymerization conditions of a random copolymer of ethylene and / or C4-C20 α-olefin and propylene. As a result, the powder bleeds beyond the formed layer, which is insufficient as a method for modifying the surface of the powder.
Accordingly, an object of the present invention is to provide a method for adding a liquid surface modifier that improves the cohesiveness of adhesive powder and to provide a soft propylene-based block copolymer that easily develops tackiness in view of the above-mentioned problems of the prior art. An object of the present invention is to provide a method for producing a propylene-based block copolymer that can produce a powder of a copolymer having good fluidity even if it is a coalescence.

  In order to solve the above problems, the present inventors have intensively studied a surface modification method for adhesive powder other than fine particles, and as a result, in the method using Si-containing oil as a surface modifier, an amorphous component is further produced. The present inventors have found a method capable of producing a propylene-based block copolymer without causing aggregation of adhesive powders by sequentially adding from the middle of the second step to the end of polymerization. And based on these knowledge, it came to complete this invention.

That is, according to the first invention of the present invention, in the first step, the propylene homopolymer or propylene / α-olefin copolymer having a C 2-20 α-olefin content excluding propylene of 5 wt% or less. In the second step, the component (A), which is a propylene / α-olefin copolymer having an α-olefin content of 15 to 80% by weight, is polymerized in the second step. The α-olefin in the step of (4) is a method for producing a propylene-based block copolymer containing at least an α-olefin having 4 to 20 carbon atoms and a proportion of the component (B) of 20 to 70% by weight,
A method for producing a propylene-based block copolymer is provided, wherein silicone oil is added at least during and at the end of polymerization in the second step.

According to a second invention of the present invention, in the first invention, the Si-containing oil is added in an amount of 500 to 4000 ppm based on the amount of the polymer polymer of the propylene-based block copolymer. A method for producing a propylene-based block copolymer is provided.
Furthermore, according to the third aspect of the present invention, there is provided a method for producing a propylene-based block copolymer, characterized in that in the first or second aspect, polymerization is performed using a metallocene catalyst.

  According to the method for producing a propylene-based block copolymer of the present invention, using an oil containing Si as a surface modifier, it is added sequentially from the middle of the second step of producing at least an amorphous component to the end of polymerization. By doing so, even if it is a soft propylene-type block copolymer which is easy to express adhesiveness, the propylene-type block copolymer from which the powder of a copolymer with favorable fluidity is obtained can be manufactured.

In the method for producing a propylene-based block copolymer of the present invention, the component (A) having 5% by weight or less of the C2-C20 α-olefin excluding propylene is polymerized in the first step, and then in the second step. In the polymerization of the propylene-based block copolymer in which 15 to 80% by weight or less of the α-olefin is polymerized and the proportion of the component (B) is 20 to 70% by weight, at least an oil containing Si is used. It is characterized in that it is added during and at the end of polymerization in the second step, or during or at the end of polymerization in the second step.
Hereafter, the manufacturing method of the propylene-type block copolymer of this invention is demonstrated concretely and in detail.

1. Oil In the method for producing a propylene-based block copolymer of the present invention, the oil used as a polymer surface modifier is an oil containing Si. In the molding process, it is desirable to use an oil that can improve the releasability. Among these, silicone oil containing Si is most desirable. The silicone oil here is a polysiloxane having an organic group such as an alkyl group and having a siloxane structure. It is preferable to use an oil having low hydrophilicity from the viewpoint of preventing a decrease in the activity of the catalyst.

  The silicone oil used is preferably composed of Si, C, and O. When other elements are included, for example, amino-modified silicone oils having amino groups and fluorine-modified silicone oils have polarity, which may lead to low activation of the catalyst.

The kinematic viscosity of the silicone oil used is preferably 50 cSt [50 mm ² / s] or more at 25 ° C., more preferably 80 cSt [80 mm ² / s] or more, preferably 10,000 cSt or less, more preferably It is 6,000 cSt or less. When the amount is not less than the above range (50 cSt), the silicone oil can be prevented from diffusing into the pores of the powder, so that the surface modification effect is improved. On the other hand, if it is below the above range (10,000 cSt), the viscosity of the silicone oil will not be too high, it will be easy to handle and the dispersion into the powder will be more uniform.

The addition amount of the silicone oil is preferably 500 ppm or more, more preferably 1000 ppm or more, further preferably 2000 ppm or more, on the other hand, preferably 4000 ppm or less, more preferably 3500 ppm or less, based on the amount of the propylene block copolymer powder. More preferably, it is 3000 ppm or less.
When the amount is not less than the above range (500 ppm), the surface modification effect is improved, the powder cohesion can be improved, and good powder fluidity can be obtained. On the other hand, if it is below the upper limit (4000 ppm) of the above range, the C3 or higher condensable gas or solvent does not dissolve in the silicone oil, and the powder does not swell and good powder fluidity can be obtained. .

2. Production Method of Polymer As the polymerization process used in the production method of the propylene / α-olefin block copolymer of the present invention, a known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method and the like can be used. Further, either batch polymerization method or continuous polymerization method can be used, and if desired, a multi-stage continuous polymerization method such as two-stage or three-stage may be used.
The propylene / α-olefin block copolymer is generally a reaction mixture of a propylene-based polymer portion [component (A)] and a propylene / α-olefin copolymer portion [component (B)]. This is because the polymerization of the propylene-based polymer part [component (A)] (first step of the previous stage) and the subsequent polymerization of the propylene / α-olefin copolymer [component (B)] (second stage of the second stage). It can be obtained by the manufacturing process of (Process).
In addition, the said component (A) may contain 5 to 5 weight% of C2-C20 alpha olefins except propylene, such as ethylene.

The catalyst used for the polymerization is not particularly limited, and a known catalyst can be used. For example, a so-called Ziegler-Natta catalyst (for example, described in the Polypropylene Handbook (published on May 15, 1998, first edition)) or a metallocene catalyst (for example, Japanese Patent Laid-Open No. Hei 5), which is a combination of a titanium compound and an organoaluminum compound. -295022) can be used.
A Ziegler-Natta catalyst is a titanium trichloride or titanium trichloride composition obtained by reduction with organoaluminum or the like as a titanium compound and treated with an electron donating compound (for example, JP-A-47-34478). JP, 58-23806, and JP 63-146906), a so-called supported catalyst obtained by supporting titanium tetrachloride on a carrier such as magnesium chloride (for example, JP 58-157808, JP-A-58-83006, JP-A-58-5310, JP-A-61-2218606, etc.).
On the other hand, about a metallocene catalyst, not only the above-mentioned literature but a well-known metallocene catalyst can be used, and it is preferable.

Examples of the organoaluminum compound used as a co-catalyst include trialkylaluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum, alkylaluminum halide such as diethylaluminum chloride and diisobutylaluminum chloride, and alkyl such as diethylaluminum hydride. Examples thereof include alkylaluminum alkoxides such as aluminum hydride and diethylaluminum ethoxide, alumoxanes such as methylalumoxane and tetrabutylalumoxane, and complex organoaluminum compounds such as dibutyl methylboronate and lithium aluminum tetraethyl. It is also possible to use a mixture of two or more of these.
In addition, various polymerization additives for the purpose of improving stereoregularity, controlling particle properties, controlling soluble components, controlling molecular weight distribution, and the like can be used for the above-described catalyst. For example, organic silicon compounds such as diphenyldimethoxysilane and tert-butylmethyldimethoxysilane, esters such as ethyl acetate, butyl benzoate, methyl p-toluate, and dibutylphthalate, ketones such as acetone and methyl isobutyl ketone, diethyl ether And electron donating compounds such as ethers such as benzoic acid and propionic acid, and alcohols such as ethanol and butanol.

As polymerization methods, slurry polymerization using an inert hydrocarbon such as hexane, heptane, octane, benzene or toluene as a polymerization solvent, bulk polymerization using propylene itself as a polymerization solvent, and polymerization of propylene as a raw material in a gas phase state Gas phase polymerization is possible. It is also possible to carry out by combining any polymerization mode. For example, component (A) is carried out by bulk polymerization and component (B) is carried out by gas phase polymerization, or component (A) is carried out by bulk polymerization followed by gas phase polymerization, and component (B) is vapor phase polymerization. The method performed in is mentioned.
In addition, for the reason of maintaining the powder fluidity of the propylene-based block copolymer, it is desirable to apply gas phase polymerization for the polymerization in the second step for producing the component (B). In addition, the polymerization mode is such that propylene homopolymerization or ethylene-propylene random polymerization is performed in the first step, and polymerization including α-olefin such as ethylene and 1-butene, which is higher than the first step, can be performed in the second step. Is desirable.
Moreover, as a polymerization form, any of a batch type (batch polymerization), a continuous type, and a semibatch type may be sufficient.
Furthermore, the polymerization reactor is not particularly limited in shape and structure, but a tank with a stirrer generally used in slurry polymerization and bulk polymerization, a tube reactor, a fluidized bed reactor generally used in gas phase polymerization, Examples include a horizontal reactor having a stirring blade.
In the gas phase polymerization, the polymerization step of the component (A) is performed by supplying hydrogen as propylene and a chain transfer agent, and in the presence of the catalyst, the temperature is 0 to 100 ° C., preferably 30 to 90 ° C., particularly preferably. The temperature is 40 to 80 ° C., the partial pressure of propylene is 0.6 to 4.2 MPa, preferably 1.0 to 3.5 MPa, particularly preferably 1.5 to 3.0 MPa, and the residence time is 0.5 to 10 hours.
It is preferable that 5% by weight or less of the α-olefin having 2 to 20 carbon atoms other than propylene is copolymerized with the component (A) as long as the effects of the present invention are not impaired.

The MFR of the component (A) of the propylene-based block copolymer used in the present invention is not particularly limited, but is usually in the range of 1 to 500 g / 10 minutes. In order to bring the component (A) of the propylene / α-olefin block copolymer into such a range, although depending on the type of the catalyst, the hydrogen of the chain transfer agent is 5 × 10 5 by hydrogen / propylene molar ratio. By performing in the range of ^{−5 to} 0.3, it is possible to adjust to a desired MFR.

When producing a propylene-based block copolymer, subsequently, in the presence of the component (A) produced in the former polymerization step (first step), in the latter polymerization step (second step), propylene, α- In the presence of the olefin (preferably an α-olefin having 2 to 20 carbon atoms excluding propylene) and hydrogen as necessary, the catalyst (the catalyst used for the production of the component (A)) is 0. To 100 ° C, preferably 30 to 90 ° C, particularly preferably 40 to 80 ° C, partial pressure of propylene and α-olefin of 0.1 to 2.0 MPa, preferably 0.1 to 1.5 MPa, residence time of 0 Copolymerization of propylene and α-olefin is carried out for 5 to 10 hours to produce component (B), and a propylene block copolymer is obtained as the final product.
Component (B) may be a copolymer of propylene and two or more α-olefins, for example, ethylene and 1-butene, as long as the effects of the present invention are not impaired. For example, a propylene / ethylene-1-butene copolymer is preferable.

The intrinsic viscosity [η] of the component (B) of the propylene-based block copolymer used in the present invention is preferably 1.0 to 2.0 dl / g. When controlling to this range, although depending on the kind of catalyst, it is possible to adjust by carrying out hydrogen / (propylene + (alpha) -olefin) molar ratio in the range of 10 < ^-5 > -0.8. Moreover, what is necessary is just to adjust the alpha olefin density | concentration with respect to the propylene density | concentration of a back | latter stage, in order to maintain the alpha olefin content in a component (B) in the range of this invention. Furthermore, in order to suppress gel generation and stickiness, it is desirable to add an alcohol such as ethanol or a gas having an unshared electron pair such as oxygen during or before the reaction of the component (B). Specifically, if it is an alcohol, it can be carried out under the condition of 0.5 to 3.0 molar ratio of alcohols / organoaluminum compound. If it is oxygen, it can carry out on the conditions of 0.01-2.0 molar ratio by the ratio of the compound of oxygen / organoaluminum. Further, the proportion of the component (B) of the propylene-based block copolymer can be controlled by the addition amount of the alcohol or the gas having an unshared electron pair.

  The polymer to which the present invention is applied is preferably homopolypropylene (propylene homopolymer), propylene-ethylene copolymer (copolymer) and propylene-ethylene-butene copolymer (copolymer) having a large amount of amorphous components. A propylene-based block copolymer comprising at least one selected from the group consisting of:

  The α-olefin content of the component (A) produced in the first step is preferably 0.5% by weight or more, more preferably 1.0% by weight or more, and further preferably 1.5% by weight or more, while the upper limit. Is 5.0% by weight or less, preferably 4.5% by weight or less, more preferably 4.0% by weight or less. If this range (5% by weight) is exceeded, the heat resistance of the powder will be significantly reduced from the first step, making it difficult to set the normal polymerization temperature.

Further, the α-olefin content contained in the component (B) produced in the second step is 15% by weight or more, preferably 20% by weight or more, more preferably 25% by weight or more, on the other hand, 80% by weight or less, preferably Is 75% by weight or less, more preferably 70% by weight or less. Below this range (15% by weight), the powder properties do not deteriorate. Above this range (80% by weight), the powder properties cannot be maintained only by the effect of the liquid surface modifier.
Further, in the propylene-based block copolymer of the polymer, the proportion of component (B) is 20% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more, on the other hand, 70% by weight or less, preferably 65%. % By weight or less, more preferably 60% by weight or less. Below this range (20% by weight), flexibility may be insufficient. On the other hand, if it exceeds this range (70% by weight), the powder may not be able to form a core-shell structure, so that significant component (B) bleeding occurs, and the powder properties may not be maintained. In general, the higher the α-olefin content contained in the amount of amorphous component produced in the second step, and the greater the production rate of the amorphous component, the more easily the amorphous component on the powder surface will bleed. Therefore, the powder adhesion is increased.

3. Method for Adding Silicone Oil Silicone oil is preferably dissolved in a solvent for ease of addition. The solvent to be used is not particularly limited as long as the silicone oil is uniformly dispersed, but a saturated hydrocarbon solvent is preferable. In particular, hexane and heptane are preferable because they are easily available and can be easily removed at the production plant.

In batch polymerization, the timing of adding silicone oil is not only the initial stage of the second step, but the component (B) polymerized in the second step is preferably 10% by weight or more based on 100% by weight of the component (B), preferably 15% by weight or more, more preferably 20% by weight or more, on the other hand, 40% by weight or less, preferably 35% by weight or less, more preferably 30% by weight or less. It is desirable to add it before stopping.
Within this range, since the amorphous component does not bleed beyond the silicone oil layer on the powder surface, the powder properties do not deteriorate. For this reason, normal stirring can be performed at the time of polymerization, the poor dispersion of the silicone oil does not occur, a part of the polymer powder does not have insufficient heat removal, and bleeding of the amorphous component does not occur.
On the other hand, in continuous polymerization, if it is a horizontal agitation reactor, it may be added from the beginning of the second step, but the polymerization amount in the second step where the deterioration of the particle properties becomes remarkable is 20% of the polymer composition. It is desirable to add silicone oil in the vicinity of the extraction tank from the middle of the reactor, which is greater than% by weight. In the case of a vertical fluidized bed, when component B is polymerized in an amount of 20% by weight or more based on the polymer composition, the agglomerated powder having deteriorated properties tends to stay in the lower part of the bed tank. More preferably, it is desirable to add silicone oil to a fluid bed height of 1/3 or less formed of powder.

4). Evaluation of powder flowability In the method for producing a propylene-based block copolymer of the present invention, evaluation of powder flowability by addition of silicone oil is a generally known method, such as particle bulk density, angle of repose, and This is done using the method for evaluating the amount of powder remaining on the sieve.

  The particle bulk density (BD) (hereinafter also referred to as BD) is one of the general fluidity indicators. It is widely known that the decrease in particle bulk density is caused by an increase in contact points between particles and an increase in particle adhesion. Also in the present invention, the B. content under the condition that the α-olefin of the component (B) other than propylene is less than 15% by weight. Based on D, powder flowability was evaluated.

  Also, the angle of repose is Like D, it is one of the general liquidity indicators. When the free surface of the powder layer is in a critical stress state, the angle formed by the powder layer surface with respect to the horizontal plane is called the angle of repose. That is, the angle of repose is an angle formed by the horizontal plate and the slope of the conical deposition obtained by continuously dropping the powder from one point in the air onto the horizontal plate. The angle of repose is measured by an injection method, a discharge method, and a gradient method. In the present invention, the evaluation was performed by using a gradient method that facilitates confirmation of the powder flow state.

  The remaining amount on the sieve was evaluated by performing the sieving operation with a 2800 μm sieve at regular intervals for 30 seconds, and evaluating the remaining amount. Although this method is not used as a general technique, it was carried out as a comparison of the adhesion between particles under conditions where shearing is applied.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples. The measuring method of each physical property value in the present invention is shown below.

1. Evaluation of powder cohesion:
(1) Measurement of bulk density (BD):
The bulk density of the polymer based on ASTM D1895-69 is shown.
(2) Angle of repose measurement:
The angle of repose at the time of rotation was measured using a repose angle measuring instrument of the Tsutsui Rikagaku Co., Ltd. type, three-wheeled cylinder rotation method.
(3) Evaluation of remaining amount on 2800 μm sieve:
The sieving work was performed at regular intervals for 30 seconds, and the evaluation was performed based on the change in the remaining amount.

[Example 1]
1. First Step: Polymerization of Polymer Component (A) After fully replacing the 3 L autoclave with stirring and temperature control with propylene, 2.76 ml (2.02 mmol) of triisobutylaluminum / n-heptane solution was added, Ethylene (16 g), hydrogen (40 ml), and liquid propylene (750 g) were introduced, and the temperature was raised to 70 ° C. to maintain the temperature. The metallocene catalyst described in JP-A-2005-132992 ([(r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H- of Production Example-1] A prepolymerized catalyst using [azurenyl}] zirconium] was slurried with n-heptane, and 12 mg of the catalyst (excluding the weight of the prepolymerized polymer) was injected to initiate polymerization.
Polymerization was continued for 30 minutes while maintaining the temperature in the tank at 60 ° C. Thereafter, the residual monomer was purged to normal pressure and further completely replaced with purified nitrogen. When a part of the produced polymer was sampled and analyzed, the MFR was 10 g / 10 min with an ethylene content of 1.6 wt%, 230 ° C. and a load of 2.16 kg.

2. Second Step: Polymerization of Polymer Component (B) Separately, a mixed gas used in the second step was prepared using an autoclave having an internal volume of 20 L having a stirring and temperature control device. The preparation temperature was 90 ° C., and the mixed gas composition was 30.7 mol% ethylene, 49.1 mol% propylene, and 20.2 mol% butene. After sampling a part of the polymer in the first step, 0.8 ml of a silicone oil having a kinematic viscosity of 100 cSt at 25 ° C. adjusted to 125 mg / ml [manufactured by Toray Dow, “SH200” 100CS] hexane solvent, This mixed gas was supplied to a 3 L autoclave, and polymerization in the second step was started. The polymerization was continued for 120 minutes at a polymerization temperature of 80 ° C. and a pressure of 2.0 MPaG. During this time, 0.8 ml of the adjusted silicone oil solution was added every 30 minutes (each time the proportion of the component (B) increased by 10 wt%). Further, 0.8 ml of the adjusted silicone oil was added immediately before the termination of the polymerization, and then 10 ml of ethanol was introduced to terminate the polymerization.
The recovered polymer was sufficiently dried in an oven. Yield is 173 g, activity is 17.8 kg / g-catalyst, the proportion of component (B) in the polymer is 52 wt%, and the content of ethylene / butene contained in component (B) is 14 wt% / 34 wt%, The recovered polymer had an MFR of 21.8 g / 10 min at 230 ° C. and a load of 2.16 kg. The polymerization rate of component (B) was 4.7 (kg / g-catalyst) / h. The addition amount of silicone oil per one time was 100 mg, and the total addition amount was 500 mg. The silicone oil concentration in the final copolymer powder amount was 2890 ppm.
The powder cohesiveness evaluation results are as follows.
-Powder BD: 0.42 g / ml
・ Repose angle: 45 °
-Residual ratio of powder on 2800 μm sieve: 0 wt%
As described above, a powder having normal powder fluidity could be obtained without causing a significant decrease in activity.
Table 1 shows the outline and evaluation results of the method for producing the propylene-based block copolymer of Example 1 above.

[Example 2]
The same operation as in Example 1 was performed except that a silicone oil hexane solvent prepared by adjusting a silicone oil having a kinematic viscosity of 5000 cSt at 25 ° C. (“SH200” 5000CS, manufactured by Toray Dow Co., Ltd.) to 125 mg / ml was used. went.
Yield is 187.6 g, activity is 19.0 kg / g-catalyst, polymer component (A) ethylene 2.2 wt%, component (A) 230 ° C., 2.16 kg load MFR 9 g / 10 min, polymer component (B ) Of 44 wt%, and the content of ethylene / butene contained in component (B) was 13 wt% / 36 wt%, respectively, and the recovered polymer was 230 ° C. and MFR 9.3 g / 10 min with a load of 2.16 kg. . The polymerization rate of component (B) was 3.7 (kg / g-catalyst) / h. The amount of silicone oil added was 500 mg, and the silicone oil concentration in the powder was 2670 ppm based on the amount of powder in the final copolymer.
The powder cohesiveness evaluation results are as follows.
-Powder BD: 0.41 g / ml
・ Repose angle: 45 °
-Residual ratio of powder on 2800 μm sieve: 0 wt%
As described above, as in Example 1, a powder having normal powder flowability could be obtained without causing a significant decrease in activity.
Table 1 shows the outline of the production method of the propylene-based block copolymer of Example 2 and the evaluation results.

[Comparative Example 1]
Before starting polymerization in the second step, add 4.0 ml of silicone oil hexane solvent with a silicone oil concentration adjusted to 150 mg / ml. The same operation as in Example 1 was performed except that no silicone oil was added.
Yield is 158 g, activity is 16.2 kg / g-catalyst, polymer component (A) ethylene 2.6 wt%, component (A) 230 ° C., 2.16 kg load MFR 9 g / 10 min, polymer component (B) The content of ethylene / butene contained in component (B) was 48 wt% and 13 wt% / 34 wt%, respectively, and the recovered polymer was 230 ° C. and MFR 17.5 g / 10 min with a load of 2.16 kg. The polymerization rate of component (B) was 3.5 (kg / g-catalyst) / h. The amount of silicone oil added was 600 mg, and the silicone oil concentration in the powder was 3800 ppm relative to the amount of powder in the final copolymer.
The powder cohesiveness evaluation results are as follows.
-Powder BD: 0.23 g / ml
-Angle of repose: The powder was agglomerated and could not be measured.
-2800 μm powder remaining ratio on sieve: 100 wt%
As described above, silicone oil was added before the polymerization in the second step, and in the middle of the polymerization in the second step and immediately before the polymerization was stopped, in Comparative Example 1 in which the silicone oil was not added, a decrease in powder BD was confirmed. In addition, the powder fluidity deteriorated so that the powder did not pass through the 2800 μm sieve.
Table 1 shows the outline of the method for producing the propylene-based block copolymer of Comparative Example 1 and the evaluation results.

[Comparative Example 2]
The same operation as in Example 1 was performed except that a hexane solvent in which alkyldiethanolamide (manufactured by Sanyo Chemical Industries, Chemistat) was adjusted to 125 mg / ml was used instead of the silicone oil.
Yield 188.9 g, activity 10.9 kg / g-catalyst, polymer component (A) ethylene 1.8 wt%, component (A) 230 ° C., 2.16 kg load MFR 5 g / 10 min, polymer component (B ), The content of ethylene / butene contained in component (B) was 11 wt% / 34 wt%, respectively, and the recovered polymer was 230 ° C. and MFR 11.1 g / 10 min with a load of 2.16 kg. . The polymerization rate of component (B) was 1.7 (kg / g-catalyst) / h. The amount of alkyldiethanolamide added was 500 mg, and the concentration of alkyldiethanolamide in the powder was 2650 ppm based on the amount of powder in the final copolymer.
The powder cohesiveness evaluation results are as follows.
-Powder BD: 0.33 g / ml
-Angle of repose: The powder was agglomerated and could not be measured.
-2800 μm powder remaining ratio on sieve: 100 wt%
As described above, liquid surface modifiers other than silicone oils containing amino groups and the like are less active than silicone oils, and are confirmed to decrease in powder BD, and the powder passes through a 2800 μm sieve. The more the powder flowed, the worse the powder flow.
Table 1 shows the outline of the method for producing the propylene-based block copolymer of Comparative Example 2 and the evaluation results.

[Reference example]
In the polymerization of the polymer component (B) in the second step, the mixed gas composition used in the second step was set to 32.8 mol% of ethylene and 70.7 mol% of propylene, and no silicone oil was added. Polymerization was carried out in the same process as in Nos. 1 and 2.
Yield is 236.1 g, activity is 26.2 kg / g-catalyst, polymer component (A) ethylene 2.2 wt%, component (A) at 230 ° C., MFR of 2.16 kg load 11 g / 10 min, polymer component (B) The content of ethylene in the component (B) was 11 wt%, and the recovered polymer was 230 ° C. and MFR 7.5 g / 10 min with a load of 2.16 kg. The polymerization rate of component (B) was 8.4 (kg / g-catalyst) / h.
The powder cohesiveness evaluation results are as follows.
-Powder BD: 0.41 g / ml
・ Repose angle: 36 °
-Residual ratio of powder on 2800 μm sieve: 0 wt%
As described above, from comparison between Examples 1 and 2 and the reference example, the soft propylene-based block copolymer obtained in Examples 1 and 2 is a hard propylene-based block copolymer containing no butene in the reference example. It can be seen that the adhesion can be suppressed to the same extent as.
Table 1 shows the outline and evaluation results of the method for producing the propylene-based block copolymer of the above reference example.

  In the method for producing a propylene-based block copolymer according to the present invention, Si-containing oil is used as a surface modifier, and is added sequentially from the middle of the second step of producing at least an amorphous component to the end of polymerization. Thus, a method capable of producing a propylene-based block copolymer without causing aggregation of adhesive powders has been found, and the industrial applicability is high.

Claims (3)

In the first step, the component (A) which is a propylene homopolymer or propylene / α-olefin copolymer having a content of α-olefin having 2 to 20 carbon atoms excluding propylene of 5% by weight or less, In the second step, the component (B) which is a propylene / α-olefin copolymer having an α-olefin content of 15 to 80% by weight is polymerized, and the α-olefin of the second step has at least 4 to 20 carbon atoms. A method for producing a propylene-based block copolymer comprising the α-olefin in an amount of 20 to 70% by weight,
A method for producing a propylene-based block copolymer, wherein silicone oil is added at least during and at the end of polymerization in the second step.   2. The method for producing a propylene-based block copolymer according to claim 1, wherein the silicone oil is added in an amount of 500 to 4000 ppm based on the amount of the polymer polymer of the propylene-based block copolymer.   The method for producing a propylene-based block copolymer according to claim 1 or 2, wherein the polymerization is carried out using a metallocene catalyst.