JPH041012B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing partially crosslinked rubber-resin compositions. More specifically, the present invention relates to a method for producing a partially crosslinked rubber-resin composition, which comprises dynamically heat treating a peroxide crosslinked olefin copolymer rubber and a peroxide decomposed polyolefin resin in the presence of an organic peroxide. Production of a partially crosslinked rubber-resin composition comprising a partially crosslinked peroxide crosslinked olefin copolymer rubber represented by ethylene/propylene copolymer rubber or ethylene/propylene/nonconjugated polyene copolymer rubber, and a polyolefin resin. has been carried out in various ways. Among these methods, there is a method in which copolymer rubber and organic peroxide are melt-kneaded in a Banbury mixer as a dynamic heat treatment to partially crosslink, and then mixed with polyolefin resin, and a method in which copolymer rubber and organic peroxide are melted in a Banbury mixer. The method of manufacturing by coexisting peroxide-decomposed polyolefin resin such as polypropylene during kneading uses a Banbury mixer, which is a batch method, and is therefore not economical. Furthermore, in the former method, the partially crosslinked rubber and polyolefin resin are often not mixed uniformly, making it difficult to obtain a product of stable quality. Partially crosslinked polymer rubber and polyolefin resin are uniformly mixed to produce a partially crosslinked rubber with stable quality.
To obtain the resin composition, the copolymer rubber and a peroxide-decomposed polyolefin resin such as polypropylene are melt-mixed in advance to form pellets, and then the pellets and organic peroxide are melt-kneaded in an extruder and dynamically mixed. It is preferable to use a heat treatment method, but in this case, a step of melt-mixing the copolymer rubber and the polyolefin resin is required prior to the dynamic heat treatment, which is also not economical. Therefore, a method is desired in which a copolymer rubber and a peroxide-decomposed polyolefin resin are melt-kneaded in the presence of an organic peroxide and subjected to dynamic heat treatment, and in which this dynamic heat treatment can be carried out continuously. If dynamic heat treatment could be performed using an extruder, it would be extremely economical;
It's also ideal. Based on this idea, the present inventors have conducted various studies in order to obtain a partially crosslinked rubber-resin composition that is uniformly mixed and has no problems in terms of physical properties. Under no circumstances can a partially crosslinked rubber-resin composition with no problems in physical properties be obtained under any conditions, and a single-screw extruder with grooves or protrusions provided on the inner surface of the cylinder to disturb the flow of the melt is used. It has been discovered that the above problem can be solved only by operating it under specific conditions. That is, the use of a specific single-screw extruder and the size of the particles of copolymer rubber fed to such a single-screw extruder have a large effect on the physical properties of the thermoplastic elastomer, and this single-screw extruder is used to The amount of mechanical energy imparted to the object has a large effect on the dispersibility of the partially crosslinked copolymer rubber and polyolefin resin, and as long as this amount, which depends on the particle size, does not exceed a certain value, the dispersibility of the partially crosslinked copolymer rubber and polyolefin resin will be uniform. Based on the knowledge that a partially crosslinked rubber-resin composition that is mixed and has good physical properties cannot be obtained, specific conditions are set there. Therefore, the present invention relates to a method for producing a partially crosslinked rubber-resin composition, which comprises forming particulate peroxide crosslinked olefin copolymer rubber and peroxide decomposed polyolefin resin into grooves on the inner surface of a cylinder. Or one with a protrusion
Directly supplied to a shaft extruder, in the presence of organic peroxide, /Kg) Manufactured by dynamic heat treatment under the following conditions. Partially crosslinked peroxide crosslinked olefin copolymer rubbers include, for example, ethylene/propylene copolymer rubber, ethylene/propylene/nonconjugated diene ternary copolymer rubber, ethylene/1-butene copolymer rubber, and ethylene/1-butene copolymer rubber.・Amorphous elastic copolymers mainly composed of olefins such as non-conjugated diene ternary copolymer rubber and ethylene-butadiene copolymer rubber, which are mixed with organic peroxides,
A rubber whose fluidity decreases or becomes non-flowable due to crosslinking when kneaded under heating is used. In these ethylene/α-olefin/(non-conjugated polyene) copolymer rubbers, ethylene and α
- Olefin is about 50/50 to 95/5, preferably about 5
It is desirable that the copolymerization is carried out at a molar ratio of 5/45 to 85/15, and dicyclopentadiene, 1,4-
When a non-conjugated polyene such as hexadiene, cyclooctadiene, methylene norbornene, or ethylidene norbornene is copolymerized, it is desirable to be present in an amount such that the iodine value is about 50 or less, preferably about 40 or less. . These copolymer rubbers have Mooney viscosity ML ₁₊₄ (100℃) of about 10~
200, preferably about 40-150. Examples of peroxide-decomposable polyolefin resins include polypropylene and propylene units.
Crystalline polypropylene resin such as a copolymer of propylene containing 85 mol% or more and α-olefin having 2 to 10 carbon atoms excluding propylene; poly(1-
butene), a crystalline poly(1-butene) resin such as a copolymer of 1-butene containing 85 mol% or more of 1-butene units and an α-olefin having 2 to 10 carbon atoms excluding 1-butene; Furthermore, poly(4-methyl-1-pentene), 4-methyl-1-pentene
2 to 10 carbon atoms, excluding 4-methyl-1-pentene and 4-methyl-1-pentene containing 85 mol% or more
Poly(4-
Examples include methyl-1-pentene (methyl-1-pentene) based resins. Among these, polypropylene resins and poly(1-butene) resins are preferred, and those having a melt index (230°C) of about 0.1 to 100, particularly about 0.5 to 50.
A polypropylene resin is desirable. What are peroxide crosslinked olefin copolymer rubber and peroxide decomposed polyolefin resin?
Generally about 10/~90 to 95/5 by weight, preferably about 20/
They are used in a ratio of 80 to 90/10. If the proportion of the copolymer rubber is less than this, the action of the organic peroxide will contribute more to the decomposition of the resin component, resulting in the disadvantage that partial crosslinking of the copolymer rubber component is insufficient, and the viscosity of the resin component will increase. If it becomes too low, it will cause poor dispersion with the partially crosslinked rubber. On the other hand, if the copolymer rubber is used in a larger proportion than this, the resin component in the resulting partially crosslinked rubber-resin composition will become smaller, resulting in lower strength, and because there is less resin component with a lower molecular weight, it will flow. Even if a resin component is further added with the intention of compensating for the lack of resin component in relation to strength, sufficient uniformity cannot be maintained. Examples of organic peroxides include dicumyl peroxide, ditert-butyl peroxide, 2,5-
Dimethyl-2,5-di(tert-butylperoxy)
Hexane, 2,5-dimethyl-2,5-di (tertiary
butylperoxy)hexyne-3,1,3-bis(tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3,
5-trimethylcyclohexane, n-butyl-
4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, Examples include tertiary butylcumyl peroxide. Among these organic peroxides, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 2,5-dimethyl-2,5-di( tert-butylperoxy)-hexyne-3,1,3-bis(tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3,
3-trimethylcyclohexane, n-butyl-
4,4-bis(tert-butylperoxy)valerate and the like are preferred, and 1,3-bis(tert-butylperoxyisopropyl)benzene is particularly preferred. These organic peroxides are used in an amount of about 0.01 to 1% by weight, preferably about 0.1 to 0.5% by weight, based on the total amount of the peroxide crosslinked olefin copolymer rubber, peroxide decomposed polyolefin resin, and optional components as described below. They are used in proportions. Each of the above components is directly fed to a specific single-screw extruder and subjected to dynamic heat treatment. At this time, the peroxide crosslinked olefin copolymer rubber is in the form of particles with a specific size (x). is used. If the particle size of this copolymer rubber is too large, it will not be possible to obtain a uniform partially crosslinked rubber-resin composition having desired physical properties.
Preferably, particulate copolymer rubber having a size of about 50 g/100 pieces or less is used. On the other hand, it is difficult to industrially produce small particles, and even if it is possible to do so, it will be expensive and therefore not economical.
A size of 0.1 g/100 pieces or more, preferably about 1 g/100 pieces or more is used. Particulate copolymer rubber having such a size is disclosed in, for example, US Patent No.
According to the method described in No. 3586089, it can be easily produced using a pelletizer that simultaneously performs the removal of the polymerization solvent and the pelletizing step. The size of the polyolefin resin particles does not necessarily have to be the same as that of the rubber particles, but it is generally preferable that the size is within the range of about 1 to 10 g/100 particles. In the production of the partially crosslinked rubber-resin composition according to the present invention, a copolymer rubber having such a particle size (x) is used, and the amount of specific energy shown in the following formula is It is fed into an extruder and subjected to dynamic heat treatment. y ≧ 0.003x + 0.12 (preferably 0.003x + 0.15) Here, the specific energy refers to the extruder driving power ( ₁ KW) performing dynamic heat treatment to empty operation (feed material) at the same screw rotation speed. It is defined as the value obtained by subtracting the driving power ( ₂ KW) in the case of no extrusion (condition without) and dividing it by the extrusion rate (QKg/hr), and therefore its unit is KW・hr/Kg. This specific energy can be adjusted by changing the operating conditions of the extruder. That is, the amount of specific energy can be increased by increasing the number of revolutions of the screw, increasing the mesh size of the screen pack, reducing the distance between the screw and the barrel, and decreasing the amount of material to be processed. The specific energy also changes depending on the shape of the screw, and if a screw with shallow grooves is used, the specific energy increases. In the present invention, it is essentially important that the amount of specific energy must be equal to or greater than the value expressed by the above formula defined by the particle size of the copolymer rubber. If the amount is less than this, only a partially crosslinked rubber-resin composition with poor dispersion and poor physical properties can be obtained.
However, the amount of specific energy is approximately 1.5KW・hr/Kg,
Preferably, it does not exceed about 1.0 KW・hr/Kg. Under conditions exceeding this, the temperature increases locally due to the conversion of mechanical energy to frictional energy, causing deterioration and physical properties of the processed material. There is a tendency to cause a decrease in energy consumption, and such excessive energy application is unnecessary and uneconomical. As a single-screw extruder that provides such specific energy, a type can be used in which the distance between the cylinder (barrel) and the screw can be arbitrarily adjusted by moving the rotating shaft back and forth.
A partial half-sectional view of such a single screw extruder is shown in FIG. A screw portion rotated by a rotating shaft 4 is accommodated in a cylinder 12 that is provided with a hopper 1, a vent 2, and a die 3, respectively. In the screw part, the deep part 5 and the shallow part 6 of the thread groove are first threaded in the axial direction when viewed from the front side of the rotating shaft, and then the outer peripheral part of the shaft is threaded in parallel to each other in a direction substantially perpendicular to the axial direction. Vertical screw parts 8, 8', 8'' having thread-like protrusions 7, 7', . After that, the deep part 5' of the thread groove is
and a shallow portion 6' is threaded in the axial direction. In such a single screw extruder, the distance between the cylinder and the screw can be arbitrarily adjusted by moving the rotating shaft 4 back and forth, and as shown in FIG. Edges 10, 1 of recessed annular grooves 9, 9', 9''
0' and the shoulders 11, 1 of the vertical screw parts 8, 8'
1', the specific energy amount can be increased. 1 with grooves or protrusions on the inner surface of the cylinder
As the screw extruder, a commercially available extruder such as an NVC type extruder (manufactured by Nakatani Kikai) or a special extruder (manufactured by Nippon Plako) can be used. In order to further enhance the disturbing effect, it is also effective to use a screw with a polygonal cross-section. On the other hand, even if you use a single-screw extruder with a straight cylinder (parallel), which is commonly used,
Although it is possible to give sufficient specific energy to the object to be treated by changing the operating conditions, it is not possible to obtain a partially crosslinked rubber-resin composition in which the partially crosslinked copolymer rubber and resin component are well dispersed. Therefore, its physical properties are also not good. Dynamic heat treatment using a specific single-screw extruder is performed at a temperature at which the material to be treated melts, generally about 200 to 280°C,
Preferably at a temperature of about 210-250°C, generally about 15
It is carried out under conditions of a residence time of ~240 seconds, preferably about 30-180 seconds. In this heat treatment process, if a crosslinking aid is present, a uniform and mild crosslinking reaction can be expected. Examples of crosslinking aids include sulfur, p-quinonedioxime, p,p'-dibenzoylquinonedioxim,
N-methyl-N,4-dinitrosoaniline, nitrobenzene, diphenylguanidine, trimethylolpropane-N,N'-m-phenylene dimaleimide, divinylbenzene, triallyl cyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate , polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, vinyl butyrate, vinyl stearate, and the like. In particular, it is most desirable to use divinylbenzene because it is easy to handle and a resin composition with well-balanced physical properties can be obtained. That is, divinylbenzene is liquid at room temperature, can dissolve organic peroxides, and has good affinity for peroxide crosslinked polymers and polypropylene resins, so it is used as a dispersion aid and diluent for organic peroxides. As an agent, it functions to improve the dispersibility of organic peroxides in each component, and particularly to bring about uniform and gentle crosslinking of peroxide crosslinked copolymer rubber components. Furthermore, divinylbenzene itself becomes a radical and acts as a chain transfer agent and a crosslinking agent, so a crosslinking effect greater than that obtained when organic peroxide is used alone as a crosslinking agent can be expected. Furthermore, since the reactivity with organic peroxides is good, divinylbenzene does not remain as a monomer in the prepared partially crosslinked rubber-resin composition, and therefore little odor is emitted. In addition, divinylbenzene is
It can also be used in the form of a mixture with other hydrocarbon compounds. The various crosslinking aids as described above are desirably used in an amount of about 2 parts by weight or less, preferably about 0.3 to 1 part by weight, per 100 parts by weight of the peroxide crosslinked copolymer rubber and resin component. If the blending ratio is higher than this, the crosslinking reaction will proceed if the blending amount of the organic peroxide is large, and as a result, the uniformity of the partially crosslinked rubber-resin composition will be lost, resulting in poor impact resistance. If the amount of peroxide blended is small, it will remain in the partially crosslinked rubber-resin composition as an unreacted monomer, and the thermal history during molding may cause changes in physical properties, so excessive use is not recommended. should be avoided. In order to improve other properties of the resulting partially crosslinked rubber-resin composition, mineral oil softeners, peroxide non-crosslinked hydrocarbon rubbers, peroxide crosslinked polyolefin resins, etc. may be blended as necessary. can. Each of these ingredients can be made to coexist during the dynamic heat treatment. Mineral oil-based softeners are effective in improving the moldability of partially crosslinked rubber-resin compositions, and are effective for improving the moldability of partially crosslinked rubber-resin compositions.
The same applies to peroxide non-crosslinked hydrocarbon rubbers such as propylene-ethylene copolymer rubbers containing 50 mol% or less of ethylene units. Additionally, peroxide crosslinked polyolefin resins such as polyethylene resins improve the strength and impact resistance of partially crosslinked rubber-resin compositions. In this way, in the present invention, by using a specific single-screw extruder and dynamic heat treatment under specific conditions, a partially crosslinked rubber-resin composition that is uniformly mixed and has excellent physical properties can be produced in one step. It has the advantage that it can be manufactured economically. Obtained partially crosslinked rubber
The resin composition can be used as it is or mixed with a peroxide cross-linked or decomposed polyolefin resin, and those with a relatively large amount of partially cross-linked copolymer rubber components can be used as thermoplastic elastomers, and those with a large amount of resin components can be used as impact resistant. Each of these is effectively used as an improved polyolefin resin composition. Next, the present invention will be explained with reference to examples. Examples [Raw materials for compounding] EPT: ethylene/propylene/dicyclopentadiene ternary copolymer rubber [ethylene/propylene molar ratio 78/22, ML ₁₊₄ (100°C) 160, iodine value 13] 100 parts by weight of minerals Contains 40 parts by weight of an oil-based softener (Idemitsu Petrochemicals PW-100) PP-1: Crystalline polypropylene with a melt index (230℃) of 12 (particle size 3g/100)
PP-2: Crystalline polypropylene copolymerized with a small amount of ethylene with a melt index (230°C) of 30 (particle size: 3 g/100 particles) PER: Propylene/ethylene copolymer rubber [mol of propylene/ethylene Ratio 70/30, [η]=
3.0dl/g (135℃, in decalin), particle size 3g/100 particles] Organic peroxide: 1,3-bis(tert-butylperoxyisopropyl)benzene [compound system] High hardness brand: EPT 70 parts (weight, (same below), PP
-1 30 parts, organic peroxide 0.3 parts and divinylbenzene 0.5 parts Low hardness brand: EPT 50 parts, PER 30 parts, PP-2 20
[Manufacturing method] EPT, PP-1 or PP-2, and depending on the brand, PER pellets, organic peroxide, and divinylbenzene were mixed in a Henschel mixer. The mixture was premixed for 60 seconds, and the mixture was fed in a predetermined amount to various extruders using a metering feeder. Sampling was performed by strand cutting from the die of the extruder. In the comparative example (Table 1 below), a regular 90 mm diameter single-screw extruder (P-90 made by Nippon Steel Corporation) was used, and the screw was fitted with a full-flight screw for pelletizing and a Dalmage screw tip with a seal ring for resin blending. We conducted Yu's two-level test (both L/D = 28). The details of the operating conditions are as follows. Cylinder temperature: C ₁ C ₂ C ₄ C ₅ 180 210 230 200 (℃) Screw rotation speed: 80 to 210 (rpm) Screen pack: 40 x 80 x 150 x 150 x 80 x 40 (mesh) total of 6 sheets stacked Use Extrusion rate: 120 to 180 (Kg/hr) In the examples and comparative examples (Tables 2 to 3 below), a 90 mm diameter special single screw extruder (manufactured by Nippon Plako, L/D = 28) was used. The amount of specific energy was varied by changing the screw rotation speed, the distance between the screw and the cylinder (barrel), and the extrusion rate. For details of its operating conditions,
It is as follows. Cylinder temperature: C ₁ C ₂ C ₃ 140 160 180 Cylinder temperature: C ₄ D 220 200 (℃) Screw rotation speed: 80 ~ 120 (rpm) Screen back: 40 x 80 x 150 x 150 x 80 x 40 (mesh) Used in a stack of 6 sheets in total Extrusion amount: 120-180 (Kg/hr) [Evaluation method] 1. Uniformity The extruded pellets were press-molded at 200℃,
A thin sheet with a thickness of 0.2 to 0.4 mm is produced, and its surface condition is visually determined. (Evaluation) 〇: Completely uniform △: Some lumpy abnormalities are observed ×: Many large lumpy abnormalities are observed 2 Moldability (1) Injection moldability Molding machine: Dynamelter (manufactured by each machine factory) Molding temperature: 200℃ Injection pressure: Primary pressure 1300Kg/cm ² : Secondary pressure 700Kg/cm ² Injection pressure: Maximum molding speed: 90 seconds/cycle Mold: 2-point gate square plate mold Molded product: 3 types of angles ( Length 300mm, width 180mm,
(Thickness: 2, 4, 7 mm) The surface condition of the square plate formed in this way is as follows:
Judgment was made visually as in the case of the sheet. (2) Extrusion moldability Molding machine: 40mm diameter extruder (manufactured by Toshiba Machine) Molding temperature: 210℃ Die: Straight die (die/core = 12.5mm/
10.0 mm) Take-up speed: 10 m/min Molded product: Tube The surface condition of the tube thus molded was visually determined in the same manner as for the sheet. 3 Basic physical properties Regarding the injection molded square plate (thickness 2 mm), based on JIS K-6301, the stress at 100% elongation,
The stress at break, elongation, surface hardness, and permanent set (100% elongation) were measured. [Results shown in Tables 1 to 3 below] Table 1: Using a single-screw extruder, changing the screw rotation speed and feed rate to increase the amount of specific energy from 0.17 to
Although the hardness was varied between 0.45 and 0.45, a high hardness composition that was satisfactory in terms of uniformity and other aspects could not be obtained. Tables 2-3: Using a single-screw extruder made by Nippon Placo,
The amount of specific energy was varied by varying the screw rotation speed, the spacing between the screw and the barrel, and the extrusion rate. From this result, in order to obtain a composition that satisfies uniformity and other points,

[Table] From this, it can be said that the specific energy (y) must be an amount as shown by the following formula with respect to the particle size (x) of the copolymer rubber. y0.003x+0.12 preferably y0.003x+0.15

[Table] Type 2: Tip dalmage with seal ring

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view of a single-screw extruder used in the present invention, and FIG. 2 is a partially cutaway sectional view showing a state in which the rotating shaft is advanced. In these drawings, reference numeral 4 indicates a rotation axis, 8 indicates a vertical screw section, 9 indicates an annular groove recessed in the inner wall of the cylinder, and 12 indicates a cylinder.

Claims (1)

[Scope of Claims] 1. Particulate peroxide crosslinked olefin copolymer rubber and peroxide decomposed polyolefin resin are directly fed into a single screw extruder having grooves or protrusions on the inner surface of the cylinder, and then in the presence of organic peroxide. , x200 y≧0.003x+0.12 However, x: Size of copolymer rubber particles (g/100 pieces) y: Specific energy of extruder (KW・hr/Kg) Dynamic heat treatment is performed under the following conditions. A method for producing a characterized partially crosslinked rubber-resin composition. 2. The method for producing a partially crosslinked rubber-resin composition according to claim 1, wherein a particulate copolymer rubber having a size of 2x of 0.1 or more is used. 3. The method for producing a partially crosslinked rubber-resin composition according to claim 1, which is subjected to dynamic heat treatment under extruder specific energy conditions where y is 1.5 or less. 4. Partially crosslinked rubber according to claim 1, in which a single screw extruder of a type in which the specific energy amount can be arbitrarily adjusted by moving the rotating shaft back and forth and adjusting the distance between the cylinder and the screw is used.
Method for producing resin composition.