JP2010116491A - Method for producing granulated resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a granulated resin composition with stable quality. <P>SOLUTION: The method for producing the granulated resin composition includes step A for measuring a revolution S<SB>PV</SB>of a cutter, step B for comparing the revolution S<SB>PV</SB>with a target revolution S<SB>SV</SB>, and step C for determining if the absolute difference of the revolutions obtained in step B exceeds the acceptable limit or not, thereby estimating the content of defective pellets without actually performing a test of the produced pellet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a granulated resin composition capable of efficiently obtaining stable quality pellets (granulated resin composition), and further controls the rotation speed of a granulator with a simple method. Thus, the present invention relates to a method for producing a granulated resin composition capable of stabilizing the particle size of pellets.

  Resin powders such as ethylene (co) polymers and propylene (co) polymers are usually kneaded together with various additives such as antioxidants, weathering agents, antiblocking agents, or antistatic agents depending on the end use. The molten resin composition is melted and kneaded by an extruder, and then the obtained molten resin composition is cut by a cutting device, pelletized, and subjected to a final product processing process.

  In the process of extruding the above molten resin composition from a granulator die, cutting, and further pelletizing, the particle size of the pellets produced is the hole diameter of the die, the number of holes, the number of blades of the cutter, and the number of rotations of the cutter It is adjusted by. Here, since the rotation speed of the cutter is fixed as equipment other than the rotation speed of the cutter, the particle diameter of the pellet is usually adjusted by adjusting the rotation speed of the cutter according to the operation state of the granulating apparatus.

  In addition, since the rotation speed of the cutter is normally set on the granulator control panel, the setting of the rotation speed of the cutter is manually changed when the feed amount of the molten resin composition to the granulator fluctuates. There was a need to do. For this reason, it has been difficult to stably obtain pellets having a stable particle size following the variation in the production amount of the pellets.

On the other hand, as another method for controlling the granulation conditions,
For example, Patent Document 1 describes a polymer granulation method for detecting the melt viscosity of a molten polymer and controlling the cutter speed based on the detected value,
In Patent Document 2, the granulated pellets are allowed to flow down on an inclined plate, the reflection luminance of the inclined plate and the granulated pellet is detected by a CCD camera, and the particle diameter of the granulated pellet is detected. A method for granulating powder by controlling the amount of powder supplied is described, and
In Patent Document 3, pellets are allowed to flow down on an inclined plate, the pellets flowing down are photographed with an ITV camera, the photographed image is processed to determine the particle size distribution of the pellets, and the granulation conditions so as to approach the target particle size distribution. A pellet particle size control method is described which corrects
JP-A-8-164519 (released on June 25, 1996) JP-A-8-89780 (published April 9, 1996) JP 2003-275570 A (published on September 30, 2003)

  However, the method described in Patent Document 1 is not always a simple method because it is necessary to constantly monitor the melt viscosity and the like of the molten polymer. Further, in order to make the pellet particle size constant, simply controlling the rotation speed of the cutter in proportion to the feed amount of the molten resin composition or the like may cause cutting failure immediately after the rotation speed control.

The method described in Patent Document 2 is to detect the particle size of the granulated pellets by detecting the reflection luminance of the granulated pellets with a CCD camera,
Since the method described in Patent Document 3 captures pellets with an ITV camera and performs image processing to determine the particle size distribution of the pellets,
These methods need to always monitor the quality of pellets using equipment such as a CCD camera and an ITV camera, and are not necessarily simple methods.

  This invention is made | formed in view of said problem, The objective is to implement | achieve the manufacturing method of the granulated resin composition from which the pellet of the stable quality is efficiently obtained by a simpler method. . Furthermore, it is in realizing the manufacturing method of the granulated resin composition which can control the rotation speed of the cutter of a granulation apparatus by a simple method, and can stabilize the particle size of the pellets manufactured.

  The inventors of the present application have made extensive studies to solve the above problems. As a result, 1) stable pellets can be obtained without constantly monitoring the viscosity and pellet quality of the molten resin composition as a raw material, and 2) simply proportional to the feed amount of the molten resin composition, etc. By simply controlling the rotation speed of the cutter, it was found that when the feed amount etc. fluctuated abruptly, the rotation speed of the cutter fluctuated abruptly and this was estimated to be a cause of cutting failure. It came to be completed.

That is, the manufacturing method of the granulated resin composition which concerns on this invention is the process A which measures the rotation speed of the cutter at the time of granulating the resin composition, and the process A in order to solve said subject. a step B of comparing the rotational speed S _PV and the target rotational speed S _SV cutter measured, it is determined whether the absolute value of the rotational speed difference obtained in step B is greater than the allowable value step C It is characterized by comprising. According to this configuration, when the absolute value exceeds the allowable value in Step C without actually inspecting the manufactured pellet, the content ratio of defective pellets (granulated resin composition) is relatively high. If it does not exceed, there is an effect that it can be predicted that the content ratio of defective pellets may be relatively low.

  In the method for producing a granulated resin composition according to the present invention, when it is determined in step C that the absolute value exceeds the allowable value, the absolute value is within the allowable value range. It is preferable to include a step D for controlling the rotation speed of the cutter stepwise, and it is more preferable that this control is performed so that the control amount of the rotation speed per unit time is constant. Thereby, the rapid fluctuation | variation of the rotation speed of the cutter at the time of control is suppressed, cutting failure is prevented, and a high quality pellet can be manufactured stably.

  In the method for producing a granulated resin composition according to the present invention, the resin composition may be an ethylene polymer or a propylene polymer. The resin composition is selected from the group consisting of one or more additives selected from the group consisting of antioxidants, lubricants, antistatic agents, and antiblocking agents, and / or low density polyethylene and rubbers. One or two or more modified resin agents may further be included. Thereby, the film performance such as mechanical performance such as strength and elasticity of the resin composition and / or transparency and slipperiness can be adjusted.

In the method for producing a granulated resin composition according to the present invention, it is preferable to further use a value calculated by the following formula (1) as the target rotational speed S _SV . Thereby, the target rotation speed S _SV can be easily determined according to the granulation load.

(However, in formula (1), Q (ton / hour) is the throughput of the resin composition, P _N (pieces / g) is the target number of pellets, H _N (pieces) is the number of holes in the die plate, B _N (sheets) represents the number of cutter blades, and α represents an adjustment parameter.)
When granulating the resin composition, the ideal target rotational speed (that is, the formula (1)) obtained by only items other than the adjustment parameter (α) in the formula (1) according to the state of the hole in the die plate and the like. The target number of revolutions obtained by fixing α to 1) may cause the number of pellet grains to slightly deviate from the target. An adjustment parameter α can be used to adjust this deviation. The value of the adjustment parameter α is usually around 1. α is a value obtained by dividing the pellet target grain number P _N (pieces / g) by the pellet grain number (pieces / g) per 1 g of the resin composition obtained by granulation at the ideal target rotational speed. .

  According to the manufacturing method of the granulated resin composition which concerns on this invention, there exists an effect that it can estimate whether the content rate of a defective pellet is comparatively high or low, without actually inspecting a pellet.

  Further, according to the method for producing a resin composition according to the present invention, rapid fluctuations in the rotation speed of the cutter during control are suppressed, cutting defects are prevented, and high-quality pellets can be stably produced. There is an effect.

  Hereinafter, embodiments of the present invention will be described in detail.

[Method for producing granulated resin composition]
The method for producing a granulated resin composition according to the present invention is a method for producing a granulated resin composition using a rotating cutter, as will be described in detail below. (1) When granulating a step a of measuring: _(unit rpm _{S PV),} (2) the rotational speed of the cutter measured in step a _{(S PV)} and the target rotational speed of the cutter rotational speed of the cutter _{(S SV:} units rpm) preparative step B of comparing, (3) the absolute value of the rotational speed of the difference calculated in step B and step determines whether exceeds the allowable value _{ΔE C (| | S PV -S} SV) , Comprising. Furthermore, if necessary, if it is determined in step C that the absolute value of the rotational speed difference exceeds the allowable value ΔE, the absolute value of the rotational speed difference is equal to the allowable value ΔE. The process D which controls the rotation speed of the said cutter in steps so that it may become in the range is included. Hereinafter, each process AD and term are demonstrated in detail.

(cutter)
The cutter (cutting means) used in the production method of the present invention is a rotary cutter that can be used for granulation of a resin composition, and any cutter can be used as long as the number of rotations can be controlled. be able to. For example, 1) Cold cut method produced by extruding resin melted by a kneader, an extruder, etc. from a nozzle such as a die plate, passing through a water tank, etc., cooling, and then cutting to a predetermined length with a cutter, 2) A hot cut method in which a columnar material extruded from a nozzle is directly cut into a predetermined length with a cutter, or 3) a columnar material extruded from a nozzle is directly cut into a predetermined length with a cutter in water. Examples thereof include a rotary cutter provided in a cutting device such as an underwater cut method manufactured by cutting. The form of the kneader, the extruder, etc. used for kneading and melting the resin is not particularly limited.

(Resin composition)
The resin composition to which the production method of the present invention is applied is not particularly limited as long as it is a composition containing a resin (raw material resin), but is preferably a composition containing a resin as a main component. However, the “modified resin agent” described later in the present invention is a kind of additive and is not included in the category of the resin as long as it is used for the purpose of modifying the raw material resin. Here, “containing resin as a main component” means that the resin content (in terms of weight) in the resin composition is any other composition (that is, other than resin) constituting the resin composition (each described later) "Additives") means more than that, and further includes only resin.

  Examples of the resin include ethylene homopolymer / copolymer (collectively referred to as ethylene polymer), propylene homopolymer / copolymer (collectively referred to as propylene polymer), isobutene homopolymer / copolymer, vinyl chloride homopolymer / Copolymer, Acrylonitrile homopolymer / Copolymer, Styrene homopolymer / Copolymer, Vinyl acetate homopolymer / Copolymer, Methyl methacrylate homopolymer / Copolymer, Vinylidene chloride homopolymer / Copolymer, Tetrafluoroethylene homopolymer / Copolymer Mention may be made of vinyl polymers such as coalescence. From the viewpoint of good processability and easy pelletization, an ethylene polymer or a propylene polymer is preferred.

  Various additives may be included in the resin composition as necessary. Examples of the additive include 2,6-di-t-butyl-4-methylphenol, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, , 3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis [(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane , Distearyl pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl), pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4 -Di-t-butylphenyl) 4,4'-biphenylenediphosphonite and other antioxidants, erucic acid amide, stearic acid Lubricants such as amides and stearic acid monoglycerides, antistatic agents such as quaternary ammonium salts and alkyl phosphates, silica, clay, talc, diatomaceous earth, feldspar, kaolin, zeolite, kaolinite, wollastonite, sericite, amorphous Antiblocking agents such as aluminosilicate and amorphous calcium silicate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {(2 , 2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], poly [(6-morpholino-1,3, 5-triazine-2,4-diyl) {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2, , 6-tetramethyl-4-piperidyl) imino}] and the like, neutralizers such as hydrotalcite, additives such as colorants, heat stabilizers and plasticizers; low density polyethylene (density 0.910 or higher) And a modified resin agent selected from rubbers (elastomers) such as ethylene propylene rubber. What is necessary is just to select the kind and usage-amount of these additives suitably according to the kind of resin and the physical property calculated | required by the resin composition.

  These resins are provided, for example, as a resin powder, and after being melted and kneaded under the desired conditions together with the above-described additives used as necessary, they are provided as a molten resin composition to a granulation step.

(Process A)
Step A is a step of measuring the rotational speed ( _SPV : unit rpm) of the cutter during granulation. The measurement can be performed by any known method. Specifically, for example, the cutter rotational speed display of the granulating apparatus to which the cutter is attached is checked or calculated from the rotational speed of the motor that rotates the cutter. Thus, the method of obtaining the rotation speed ( _SPV ) during operation is preferable in terms of simplicity. In addition, the said process may be performed by an operator or may be automatically performed by control means, such as a computer. An automatic configuration is preferable from the viewpoint of ease of control.

(Process B)
Step B is a step of comparing the rotation speed (S _PV ) of the cutter with the target rotation speed (S _SV : unit rpm) of the cutter, and more specifically, the absolute value of the difference between both rotation speeds ( | S _PV -S _SV |). Here, the target rotational speed of the cutter refers to the optimum rotational speed of the cutter that is required to stably obtain the desired pellet (that is, the granulated resin composition), for example, the desired pellet. State (for example, particle size, weight, etc.), resin composition throughput (feed amount), resin composition viscosity, cutting device used (number of cutter blades, number of die plate holes, etc.), etc. It can be set as appropriate according to the conditions. For example, granulation is performed by operating a cutting device to be used as a test, and the rotation speed of a cutter that can obtain the most suitable pellet may be set as the target rotation speed.

In addition, the inventors of the present application, in particular, treat the resin composition (resin and additive) per unit time Q (ton / hour), the target number of pellets P _N (pieces / g: ie 1 g of resin composition) The target rotational speed is calculated by paying attention to the number of pellets to be granulated), the number of holes in the die plate H _N (pieces) of the cutting device, and the number of cutter blades B _N (sheets) of the cutting device. I am finding out what I can do for the first time. That is, in the present invention, the target rotational speed (S _SV ) can be determined by the above equation (1), and according to this method, the target rotational speed is easily determined according to the granulation load applied to the granulator. This is preferable.

Here, the alpha in the formula (1) an adjustment parameter determined by such conditions of the die plate, specifically, the target particle number P _N pellets, adjustment parameters in the formula (1) (alpha) It can be determined as a value divided by the number of pellet particles obtained by granulation at the ideal target rotational speed obtained only with the other items. The value of the adjustment parameter α is usually around 1.

  In addition, the said process may be performed manually by an operator, or may be automatically performed by control means, such as a computer. An automatic configuration is preferable from the viewpoint of ease of control.

(Process C)
Step C The absolute value of the obtained rotational speed difference in step _{B (| S PV -S SV |} ) allowable value (hereinafter referred to as tolerance Delta] E) is a step of judging whether or not exceeded . Here, the allowable value ΔE refers to the range of the rotational speed of the cutter in which a desired pellet can be stably obtained even when the target rotational speed S _SV is exceeded or below. The allowable value ΔE may be any value as long as the desired pellet can be stably obtained. However, the smaller the deviation from the target rotational speed, the better. Therefore, the allowable value ΔE is within the range of 0 rpm or more and S _SV × 10% or less. Is more preferable, and it is more preferably within a range of 0 rpm or more and S _SV × 5% or less, and further preferably within a range of 0 rpm or more and S _SV × 1% or less.

  According to this process C, the content rate of defective pellets (granulated resin composition) becomes relatively high when the absolute value exceeds the allowable value without actually inspecting the manufactured pellets. If not, it can be expected that the content of defective pellets may be relatively low. In addition, the said process may be performed manually by an operator, or may be automatically performed by control means, such as a computer. An automatic configuration is preferable from the viewpoint of ease of control.

(Process D)
Step D, the absolute value of the difference of the rotational speed in step _{C (| S PV -S SV |} ) when it is determined to exceed the allowable value Delta] E, within the absolute value of the tolerance Delta] E This is a step of controlling the rotational speed of the cutter step by step so that When the absolute value is within the allowable value ΔE, pellets having a desired particle size and the like can be stably obtained, and therefore it is not necessary to control the rotational speed of the cutter.

  What is important here is that when the absolute value exceeds the allowable value ΔE, the number of rotations of the cutter is “stepwise controlled” and adjusted so that the absolute value falls within the range of the allowable value ΔE. It is. That is, instead of adjusting the absolute value to be within the allowable value ΔE by decreasing the rotational speed at a time for the rotational speed exceeding the allowable value ΔE or increasing the rotational speed at a time, step by step. It is important to control the rotational speed of the cutter. Thereby, the rapid fluctuation | variation of the rotation speed of a cutter can be suppressed and generation | occurrence | production of the cutting defect at the time of pellet manufacture can be suppressed. Thereby, the particle size etc. of the manufactured pellet can be stabilized and a higher quality pellet can be obtained.

  The method of controlling the rotation speed of the cutter stepwise can be performed, for example, by 1) gradually increasing or decreasing the control amount of the rotation speed per unit time (one control cycle). It is also possible to carry out such that the control amount of the rotation speed per unit time (one control cycle) becomes a constant amount (sometimes referred to as ΔMV). From the viewpoint of control stability, it is preferable to control the rotational speed of the cutter stepwise so that the control amount per unit time becomes a constant amount.

  The rotation speed of the cutter may be controlled by an operator of the granulating device operating the device control panel or the like, or automatically controlled by the granulating device or an external computing device. Also good. From the viewpoint of ease of control, a configuration that is automatically controlled by a granulating device or an external arithmetic device is preferable.

  The manufacturing method of the granulated resin composition which concerns on this invention may further include the process of collect | recovering the granulated resin composition in addition to the said process A)-process D).

[Granulator for resin composition]
An example of a granulating apparatus to which the production method of the present invention is applied will be described below with reference to FIG. FIG. 1 is a schematic diagram illustrating the configuration of a granulation apparatus to which the production method according to the present invention is applied.

An example of the granulating apparatus is provided with a cutter which rotates, comparison means for comparing the rotational speed S _PV and the target rotational speed S _SV cutter, the absolute value of the rotational speed of the difference comparing means has calculated (| Control means for controlling the rotational speed of the cutter stepwise so that the absolute value falls within the allowable value range when S _PV -S _SV |) exceeds the allowable value.

  More specifically, the granulating apparatus includes a process control computer (control means / comparison means) 1, a granulator field control panel (manual control means) 2, and a cutter provided in the granulator field control panel 2. A control unit composed of a rotation speed controller 3; a raw material resin supply unit composed of a raw material resin storage tank 4 and a raw material resin feeder 5; and a modified resin agent supply composed of a modified resin agent storage tank 6 and a modified resin agent feeder 7. And an additive supply unit composed of an additive storage tank 8 and an additive feeder 9; and a granulation unit composed of a granulator main body 10 and a cutting device 11.

  The raw material resin storage tank 4 is connected to the upstream side of the granulator body 10 via the raw material resin feeder 5 and supplies the raw material resin into the granulator body 10. The modified resin agent storage tank 6 is connected to the upstream side of the granulator main body 10 via the modified resin agent feeder 7 and supplies the modified resin agent (additive) into the granulator main body 10. The additive storage tank 8 is connected to the upstream side of the granulator main body 10 via the additive feeder 9 and supplies the additive (additive) into the granulator main body 10.

  In the granulator body 10, the raw resin, the modified resin agent, and the additive are melted and kneaded, and the obtained molten resin composition is supplied from the upstream side to the downstream side of the granulator body 10. Subsequently, the molten resin composition is extruded into the cutting device 11 from a die (not shown) provided on the downstream side of the granulator body 10. In the cutting device 11, the molten resin composition is cut and pelletized by a rotating cutter (not shown).

The process control computer 1 controls the operation of the entire apparatus. Specifically, the process control computer 1 receives, via the cutter rotation speed adjuster 3, information on the rotation speed of a motor that rotates the cutter (that is, the actual rotation speed S _PV of the cutter) (step A). Equivalent to Also, the supply amount (feed of resin, additive and modified resin agent to the granulator main body 10 from the modified resin agent feeder 7, the raw material resin feeder 5 and the additive feeder 9 to the process control computer 1 (feed). Quantity) information is entered. The process control computer 1 automatically controls the rotational speed of a cutter (not shown) provided in the cutting device via the cutter rotational speed adjuster 3 based on the supply amount information.

Specifically, in the process control computer 1, the processing amount Q (that is, the granulation load) in the above formula (1) is always calculated by adding the above supply amount information. The process control computer 1 is set in advance with the target number of pellets P _N , the number of holes H _N of the die plate, the number of cutter blades B _N , and the adjustment parameter α. Is used to calculate the target rotational speed (S _SV ).

In process control computer 1 further of the cutter rotational speed _{(S PV)} and target speed of the cutter and compare the _{(S SV)} and the absolute value of the difference between both rotational speed _{(| S PV} -S _{SV |)} Is calculated (corresponding to step B).

In process control computer 1 further absolute value of the rotational speed of the difference obtained in step _{B (| S PV -S SV |} ) is, it is determined whether or not it exceeds a preset allowable value Delta] E (step Equivalent to C). If the absolute value is within the range of the allowable value ΔE, the granulator is in a state of stably producing the desired pellets, and therefore it is not necessary to control the rotational speed of the cutter. On the other hand, when the absolute value exceeds the allowable value ΔE, the process control computer 1 sends a control signal for controlling the rotational speed of the cutter stepwise to the motor via the cutter rotational speed adjuster 3. Thus, the absolute value is automatically adjusted so as to be within the range of the allowable value ΔE (corresponding to the process D). The method for controlling the rotational speed of the cutter stepwise is as described above. For example, in the process control computer 1, a value obtained by dividing the total rotational speed control amount by the target control time is calculated, and then a unit time (one control cycle). It is preferable to send a control signal to the motor so that the control amount of the number of rotations per unit) becomes a constant amount.

  If the method for producing a granulated resin composition according to the present invention applied to the above granulator is used, the cutter rotational speed can be automatically controlled according to the granulation load, and the pellet particle size can be stabilized. it can. In some cases, the control of the rotational speed of the cutter can be manually performed by the operator through the cutter rotational speed adjuster 3 provided in the granulator field control panel 2.

[Granulation condition control method]
The manufacturing method of the granulated resin composition which concerns on this invention is 1) the process A which measures the rotation speed of the cutter at the time of granulating the resin composition, and 2) the rotation speed S of the cutter measured at the process A. Step B for comparing _PV with the target rotational speed S _{SV of the} cutter, and 3) The absolute value of the difference in rotational speed obtained in Step B (| S _PV -S _SV |) exceeds the allowable value ΔE. Step C for determining whether or not, and if necessary, 4) If it is determined in Step C that the absolute value of the difference between the rotation speeds exceeds the allowable value ΔE, A granulation condition control method further including a step D of controlling the rotational speed of the cutter stepwise so that the absolute value falls within the range of the allowable value ΔE can be used.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  Next, although an Example is given and this invention is demonstrated concretely, this invention is not limited to this.

[Example 1]
In the present Example, the pelletization apparatus which shows a schematic structure in FIG. 1 was used, and the polypropylene resin composition was granulated, and the product pellet was manufactured. Incidentally, the granulation apparatus is a twin screw granulator having a number of holes H _{N =} 14 pieces of the die plate, and a cutter having a number B _{N =} 6 sheets of the cutter blade.

Here, 57 the target particle number _{P N} of the pellets / g, the adjustment parameter alpha 0.990, to set to 1 rpm / sec fluctuations rpm ΔMV per 5 rpm, 1 control cycle the tolerance Delta] E, Table The process control computer 1 is configured to calculate the target rotational speed (S _SV ) based on the formula (1) according to the processing amount Q (ton / hour) shown in FIG. In process control computer 1 further rotational speed of the cutter during operation _{(S PV)} and target speed of the cutter and compare the _{(S SV)} and both the rotational speed of the absolute value of the difference _{(| S PV} -S _SV |) Is calculated. Sonouede, the absolute value if it exceeds the range of allowable values Delta] E, so as to return within the rapidly tolerance Delta] E, and automatically controlling the rotational speed S _PV cutter.

The granulator body under the conditions shown in Table 1, with polypropylene resin as the raw material resin (raw material resin), low-density polyethylene resin as the modified resin (additive), and antioxidant as the additive (additive) 10 to produce pellets (granulated resin composition). In addition, the processing amount Q in Table 1 is the total of the feed amounts of the raw resin, the modified resin, and the additive. Moreover, MFR in Table 1 refers to the melt flow rate of a molten resin composition (a molten mixture of a raw material resin and an additive) to be melted and kneaded. Furthermore, the average rotational speed (rpm) in Table 1 refers to the average value of the cutter rotational speed during the operation period of the granulator. That is, the average rotation speed of the cutter was within the range of the target rotation speed S _SV and ± 3 rpm.

The results of operation by this method are shown in Table 1 as Experiment Nos. 1-4. From this result, according to the method of the present invention, product pellets having a stable particle number and particle size close to the target particle number P _N (57 particles / g), which were 56 to 60 particles / g, could be obtained. . Note that the number of pellets produced from a certain amount of the resin composition being substantially the same as the target value means that a pellet having a desired particle size is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing efficiently the granulated resin composition (pellet) of the stable quality can be provided. The granulated resin composition obtained by the present invention has stable quality and is suitably used for the purpose of producing a final product made of resin.

It is the schematic explaining an example of the granulation apparatus with which the method concerning this invention is applied.

Explanation of symbols

1 Process control computer (control means / comparison means)
2 Granulator Site Control Panel 3 Cutter Rotation Speed Controller 4 Raw Material Resin Storage Tank 5 Raw Material Resin Feeder 6 Modified Resin Agent Storage Tank 7 Modified Resin Agent Feeder 8 Additive Storage Tank 9 Additive Feeder 10 Granulator Main Body 11 Cutting device

Claims (6)

A method for producing a granulated resin composition using a rotating cutter,
Step A for measuring the rotational speed of the cutter when granulating the resin composition;
Step B for comparing the rotation speed S _{PV of the} cutter measured in Step A above with the target rotation speed S _{SV of the} cutter,
And C for determining whether or not the absolute value (| S _PV -S _SV |) of the difference in the rotational speed obtained in the step B exceeds an allowable value. A method for producing a granular resin composition.   When it is determined in step C that the absolute value of the rotational speed difference exceeds the allowable value, the absolute value of the rotational speed difference is within the allowable value range. The method for producing a granulated resin composition according to claim 1, further comprising a step D of controlling the rotational speed stepwise.   3. The granulated resin composition according to claim 2, wherein in step D, the stepwise control of the rotation speed of the cutter is performed such that the control amount of the rotation speed per unit time is constant. Manufacturing method.   The method for producing a granulated resin composition according to any one of claims 1 to 3, wherein the resin composition is an ethylene polymer or a propylene polymer.   The resin composition is selected from the group consisting of one or more additives selected from the group consisting of antioxidants, lubricants, antistatic agents, and antiblocking agents, and / or a group consisting of low density polyethylene and rubbers. Alternatively, the method for producing a granulated resin composition according to any one of claims 1 to 4, further comprising two or more modified resin agents. _{6. The} method for producing a granulated resin composition according to claim 1, wherein a value calculated by the equation (1) is used as the target rotation speed S _SV .

However, in Formula (1), Q (ton / hour) is the throughput of the resin composition, P _N (pieces / g) is the target number of pellets, H _N (pieces) is the number of holes in the die plate, B _N (Sheet) represents the number of cutter blades, and α represents an adjustment parameter.

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