JPS6365100B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polypropylene resin composition. More particularly, the present invention relates to a method for producing a polypropylene resin composition having improved impact resistance and low temperature embrittlement. In order to improve impact resistance and low-temperature embrittlement, which were considered to be the essential drawbacks of polypropylene resin, olefin copolymer rubbers such as ethylene/propylene copolymer rubber, ethylene/propylene/diene ternary copolymer rubber, or Blending polyethylene resin and the like with polypropylene resin has been well known (for example, Japanese Patent Publications No. 39-18746, Japanese Patent Publication No. 41-7345, Japanese Patent Publication No. 45-22626, etc.). However, modification using these blends often impairs the excellent rigidity inherent in polypropylene resins, and as a result, polypropylene resins with a sufficient balance of rigidity, impact resistance, and low-temperature embrittlement resistance are produced. It was not possible to obtain a resin mixture. In view of the current situation, the present inventors have conducted various studies to improve the impact resistance and low-temperature embrittlement of polypropylene resin without essentially impairing its rigidity. By mixing partially co-crosslinked olefin copolymer rubber and polyethylene resin in a specific ratio,
It has been found that the above problem can be solved. Therefore, the modified polypropylene resin composition of the present invention contains 10 to 90% by weight of peroxide crosslinked olefin copolymer rubber and 90% by weight of polyethylene resin.
Peroxide crosslinked polymer consisting of ~10% by weight
10 to 200 parts by weight of a polypropylene resin and an organic peroxide are added to 100 parts by weight, and this is dynamically heat-treated to obtain a processed material, in which each 100 parts by weight of the peroxide crosslinked polymer is allowed to coexist during the dynamic heat treatment. It is manufactured by mixing polypropylene resin in an amount of 150 to 600 parts by weight, including the amount. 100 parts by weight of a peroxide crosslinked polymer consisting of a peroxide crosslinked olefin copolymer rubber and a peroxide crosslinked polyolefin resin such as a polyethylene resin, and 10 parts by weight of a peroxide non-crosslinked polyolefin resin such as a polypropylene resin.
The method of obtaining a thermoplastic elastomer by adding ~100 parts by weight and dynamically heat-treating this in the presence of an organic peroxide is disclosed in JP-A-55-71739, which describes the invention filed by the present applicant. It is described in. Such a thermoplastic elastomer can also be prepared by adding 100 parts by weight of the above peroxide crosslinked polymer in the presence of a peroxide non-crosslinked polyolefin resin such as polypropylene (the amount of which is in the range of 10 to 100 parts by weight below). (with or without the presence of organic peroxide), by dynamically heat-treating it with an organic peroxide and mixing the resulting treated material with a peroxide-non-crosslinked polyolefin resin in an amount of 10 to 100 parts by weight. can also be manufactured. In such conventional technology, the upper limit of the peroxide non-crosslinked polyolefin resin is limited to 100 parts by weight per 100 parts by weight of the total amount of partially co-crosslinked peroxide crosslinked polymers, which means that the upper limit of the peroxide non-crosslinked polyolefin resin is limited to 100 parts by weight. If used, the rubber-like properties will be lost, making it impossible to obtain the desired thermoplastic elastomer.Therefore, as long as such thermoplastic elastomers are used as the desired product, rigidity is essentially important. It is not considered a property. However, polypropylene resin per 100 parts by weight of the total amount of partially co-crosslinked peroxide crosslinked polymer.
By mixing 150 to 600 parts by weight, a resinous composition mainly composed of polypropylene resin is formed according to the mixing ratio between the two, and the polypropylene resin composition has rigidity, impact resistance, The low-temperature embrittlement properties are well balanced, resulting in a modified polypropylene resin that is essentially different from the thermoplastic elastomer. The polypropylene resin modified in this way is polypropylene, or a propylene such as a copolymer of propylene containing 85 mol% or more of propylene units and an α-olefin having 2 to 10 carbon atoms (excluding propylene). Polymer resin is used, especially melt index (230℃)
is preferably about 0.1 to 100, particularly about 0.5 to 50. Examples of peroxide crosslinked olefin copolymer rubbers include ethylene/propylene copolymer rubber, ethylene/propylene/nonconjugated diene ternary copolymer rubber, ethylene/1-butene copolymer rubber, and ethylene/1-butene/nonconjugated diene copolymer rubber. It is an amorphous elastic copolymer mainly composed of olefins such as tertiary copolymer rubber and ethylene-butadiene copolymer rubber, and is crosslinked by mixing with organic peroxide and kneading under heating, resulting in fluidity. Rubbers that degrade or become non-flowing are used. In these ethylene/α-olefin/(non-conjugated polyethylene) copolymer rubbers, the ratio of ethylene and α-olefin is about 50/50 to 85/15, preferably about
It is desirable that the copolymerization is carried out at a molar ratio of 55/45 to 80/20, and further dicyclopentadiene, 1,4
- When a non-conjugated polyene such as hexadiene, cyclooctadiene, methylene norbornene, ethylidene norbornene is copolymerized, it may be present in an amount such that the iodine value is less than about 50, preferably less than about 40. desirable. These copolymer rubbers have a Mooney viscosity ML ₁₊₄ (100℃) of approximately 10
-200, preferably about 40-150; if the Mooney viscosity is less than this, only a resin composition with poor impact resistance will be obtained, whereas if it is more than this, when partially co-crosslinked, the The dispersibility of the partially co-crosslinked product deteriorates, and the impact resistance and appearance of the molded product deteriorate. Peroxide cross-linked polyethylene resins include low-density to high-density polyethylene, or combinations of ethylene containing 85 mol% or more of ethylene units, α-olefins having 3 to 8 carbon atoms, vinyl acetate, acrylic esters, methacrylic esters, etc. Ethylene-based polymer resins such as copolymers are used, especially those with a melt index (190℃) of about 0.01.
-200, especially about 0.1-100 are preferred. These polyethylene resins contribute to improving the impact resistance and low-temperature embrittlement of the resin composition by partially co-crosslinking with the olefin copolymer rubber during dynamic heat treatment in the presence of an organic peroxide. do. In both cases, the weight ratio of peroxide crosslinked olefin copolymer rubber and polyethylene resin is 10/90.
It is used at a ratio of ~90/10, preferably from 30/70 to 80/20; if the ratio is outside this range, a resin composition with improved impact resistance and low-temperature embrittlement cannot be obtained. Partially co-crosslinked product of olefin copolymer rubber and polyethylene resin in such proportions
The polypropylene resin is 150 to 100 parts by weight.
A polypropylene resin composition according to the present invention is produced by mixing in a proportion of 600 parts by weight, which is preferably produced by the following method. Peroxide crosslinked olefin copolymer rubber 10
~90% by weight and polyethylene resin 90-10% by weight
100 parts by weight of a peroxide crosslinked polymer consisting of
10-200 parts by weight of polypropylene resin, preferably
10 to 100 parts by weight, more preferably 30 to 80 parts by weight, and a small amount of organic peroxide crosslinking agent are added, which is first subjected to a dynamic heat treatment. The reason for coexisting polypropylene resin during this dynamic heat treatment is to improve the compatibility when the polypropylene resin is further mixed into the processed material, and to improve the fluidity of the processed material due to the presence of peroxide-decomposed polypropylene resin. The objective is to prevent this from occurring, and as a result, the partially co-crosslinked product of the peroxide crosslinked polymer is uniformly mixed with the polypropylene resin. Therefore, if the coexistence ratio of polypropylene resin is less than this, such an effect cannot be obtained, whereas if it is used in a larger amount than this, the ratio of polypropylene resin decomposed by peroxide will be relatively large, and the impact resistance will ultimately decrease. An improved resin composition cannot be obtained. The organic peroxide is preferably used in a proportion of 0.05 to 1 part by weight per 100 parts by weight of the peroxide crosslinked polymer and polypropylene resin; if the proportion is less than this, partial co-crosslinking will be insufficient and the desired result will not be achieved. A resin composition having impact resistance cannot be obtained, and on the other hand, if more than this amount is used, the crosslinking density becomes high and the dispersibility in the polypropylene resin deteriorates, so that the impact resistance cannot be improved. Examples of organic peroxides include dicumyl peroxide, ditertiary butyl peroxide, 2,5
-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-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 , tert-butylcumyl peroxide, and the like. 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)parelate and the like are preferred, and 1,3-bis(tert-butylperoxyisopropyl)benzene is particularly preferred. The dynamic heat treatment is carried out by melting and kneading a peroxide crosslinked polymer, a polypropylene resin, a crosslinking aid blended as necessary, and the like in the presence of an organic peroxide. Generally, a peroxide crosslinked polymer and a polypropylene resin are mixed in advance, and in a uniformly kneaded state,
This is done by adding and kneading the organic peroxide and other optional ingredients. The equipment used for this melt kneading includes an open type mixing roll, a closed type Banbury mixer, an extruder,
Commonly used devices such as kneaders and continuous mixers are used. Among these, it is preferable to use a closed-type device and knead in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas.If you use an extruder etc. that has a sufficient kneading effect, the above steps can be completed all at once. can be done. Melt kneading is generally carried out at a temperature of about 150-280°C, preferably about 170-240°C, for about 1-20 minutes, preferably about 3-10 minutes. When a crosslinking aid is present in the heat treatment process, a uniform and mild crosslinking reaction can be expected. As a crosslinking aid, sulfur, p-quinonedioxime,
p,p'-dibenzoylquinone dioxime, 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, etc. are used. 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 polymer components. Also,
Since divinylbenzene itself becomes a radical and acts as a chain transfer agent and a crosslinking agent, it can be expected to have a greater crosslinking effect than when organic peroxide is used alone as a crosslinking agent. In addition, since the reactivity with organic peroxides is good, divinylbenzene does not remain as a monomer in the prepared resin composition, and therefore little odor is emitted.
Note that divinylbenzene can also be used in the form of a mixture with other hydrocarbon compounds. The various crosslinking auxiliaries mentioned above are based on the total amount of peroxide crosslinked polymer and polypropylene resin.
2 parts by weight or less per 100 parts by weight, preferably 0.3 to 1
Used in parts by weight. 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 resin composition will be lost and the impact resistance will be inferior; If the amount is too low, it will remain in the resin composition as an unreacted monomer, and its physical properties may change due to the thermal history during molding, so excessive use should be avoided. The processed material obtained by such dynamic heat treatment contains 150 to 600 parts by weight of peroxide crosslinked polymer, including the amount coexisting during dynamic heat treatment, per 100 parts by weight of the peroxide crosslinked polymer.
Polypropylene resin is mixed in an amount of 200 to 400 parts by weight, preferably 200 to 400 parts by weight. At this time, it is preferable to mix at this stage at least the same amount of polypropylene resin as the polypropylene resin added during the dynamic heat treatment. If the amount of polypropylene resin mixed is less than this, the rigidity will be low, while if the amount of the polypropylene resin mixed is more than this, only a resin composition that gives a molded article with poor impact resistance will be obtained. Mixing of polypropylene resin is
They may be melted and mixed using an extruder, or the pellets of the object to be treated and the polypropylene resin pellets may be simply mixed and kneaded during melt molding. The resin composition mixed with polypropylene resin has a melt index (230℃) of approximately
It is preferable to adjust the value to a value of 0.05 to 15. In the polypropylene resin composition according to the present invention, within a range that does not impair strength or impact resistance,
Fillers, colorants, etc. can be added. Examples of fillers include calcium carbonate, calcium silicate, clay, kaolin, talc, silica,
Diatomaceous earth, mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass fiber, glass bulbs, shirasu balloons, carbon fiber, etc. are used, and colored As agents, carbon black, titanium oxide,
Zinc white, red iron, ultramarine blue, navy blue, azo pigments, nitroso pigments, lake pigments, phthalocyanine pigments, etc. are used. In addition, mineral oil, polyisobutylene, butyl rubber, amorphous propylene/ethylene copolymer with a high propylene content, etc. can be added to the resin composition for the purpose of improving the appearance of molded products. Heat-resistant stabilizers such as sulfite-based, phenylalkane-based, phosphite-based, and amine-based stabilizers, anti-aging agents, weather-resistant stabilizers, antistatic agents, and lubricants such as metal soaps and waxes may also be added in small amounts as appropriate. The polypropylene resin composition according to the present invention makes effective use of its well-balanced properties of rigidity, impact resistance, and low-temperature embrittlement, and can be used for automobile exterior parts such as automobile parts, bumpers, and molding radiator grills. It can be suitably used for molding automobile interior parts such as handles, various pillars, containers, pellets, etc. Next, the present invention will be explained with reference to examples. Example 1 Ethylene/propylene/5-ethylidene-2-
Norbornene ternary copolymer rubber [ethylene and propylene molar ratio 70/30, Mooney viscosity ML ₁₊₄ (100
℃) 70. , iodine value 15] 50 parts (weight, same below),
High-pressure polyethylene [density 0.925 g/cm ³ , melt index (ASTM-D-1238-65T, 190
℃) 4; 20 parts of polyethylene-1] and 30 parts of polypropylene [density 0.91 g/cm ³ , melt index (ASTM-D-1238-65T, 230°C) 7],
180℃ in nitrogen atmosphere using Banbury mixer
After kneading for 5 minutes, the mixture was passed through a roll and granulated into pellets using a sheet cutter (first step). next,
These pellets and a solution prepared by dissolving 0.3 parts of 1,3-bis(tert-butylperoxyisopropyl)benzene in 0.5 parts of divinylbinzene were mixed using a tumble blender to uniformly adhere the crosslinking agent solution to the pellet surface. . Thereafter, the pellets were extruded using an extruder at 210° C. in a nitrogen atmosphere to form dynamically heat-treated pellets (second step). 100 parts of this treated material was mixed with 150 parts of the same polypropylene as described above using a tumbler blender, and then extruded using an extruder at 210°C to obtain the intended polypropylene resin composition. The moldability and basic physical properties of this resin composition were evaluated by the following methods. [Test method] 1. Injection moldability (1) Molding machine used for injection molding using the following equipment and conditions: Dynamelter (manufactured by Meiki Seisakusho) Molding temperature: 200℃ Injection pressure: Primary pressure 1300Kg/cm ² , secondary pressure 700
Kg/cm ² 〃: Maximum molding speed: 90 seconds/1 cycle Gate: Direct gate (land 10 x 10 x
3mm) Molded product: 3 types of square plates (length 300mm, width 180mm)
mm, thickness 2, 4, 6 mm) (2) Appearance criteria for molded products (a) Flow marks were evaluated on the following three levels (evaluation) 〇: No flow marks observed at all △: Slightly visible on the entire surface of the molded product ×: Significantly many flow marks (b) Sink marks were evaluated on the following three levels (evaluation) 〇: No sink marks were seen at all △: Only seen on the opposite side of the gate ×: Seen over the entire surface ( c) Surface gloss was measured according to the ASTM-D-523 method at an incident angle of 60° (Evaluation) 〇: Gloss 25% or more △: Gloss 10-25% ×: Gloss 10% or less 2 Basic physical properties Thickness 2 mm obtained by injection molding using method 1 above
A test piece was cut from a square plate, and the values of the following items were measured. Tensile properties (tensile strength at break and elongation at break): : JIS K-6301 Spring strength: ASTM-D-2240 (Shore D type) Flexural modulus: ASTM-D-790 (23℃) Falling weight impact strength: Conforms to ASTM-D-1709 Izot impact strength: ASTM-D-256 (-40℃,
(notched) Low temperature embrittlement temperature: JIS K-6301 Example 2 In Example 1, the density as polyethylene
Low-pressure polyethylene (polyethylene-2) having a weight of 0.954 g/cm ³ and a melt index of 0.9 (190° C.) was used. Example 3 In Example 1, the amount of polypropylene mixed in the third step was increased to 250 parts. Example 4 In Example 1, 40 parts of ternary copolymer rubber, 15 parts of polyethylene-1, and 15 parts of polypropylene were used.
45 parts were kneaded in the first step. Example 5 In Example 4, the amount of polypropylene mixed in the third step was increased to 200 parts. Example 6 In Example 1, 30 parts of ternary copolymer rubber, 40 parts of polyethylene-1, and 40 parts of polypropylene were used.
30 parts were kneaded in the first step. Example 7 In Example 1, the first step of kneading was carried out by reducing the amount of polypropylene from 30 parts to 20 parts and adding 10 parts of polyisobutylene. Example 8 In Example 7, 20 parts of a mineral oil softener was further added and the first step of kneading was carried out. Example 9 In Example 1, the first step of kneading was carried out by increasing the amount of terpolymer rubber from 50 parts to 75 parts, and reducing the amount of polypropylene from 30 parts to 5 parts. Comparative Example 1 In Example 1, the second crosslinking step was omitted. Comparative Example 2 In Example 1, the amount of polypropylene mixed in the third step was increased to 450 parts. Comparative Example 3 In Example 1, 170 parts of polyethylene and 30 parts of polypropylene were kneaded in the first step, without using the ternary copolymer rubber, and in the second step, 1,
3-bis(tert-butylperoxyisopropyl)
A solution of 0.1 part of benzene dissolved in 0.3 part of divinylbenzene was used as the crosslinking agent. Comparative Example 4 In Comparative Example 3, the same amount of crosslinking agent solution as in Example 1 was used. The results obtained in each of the above Examples and Comparative Examples are shown in Tables 1 and 2 below.

【table】

Claims (1)

[Claims] 1. Peroxide crosslinked olefin copolymer rubber
10 to 200 parts by weight of polypropylene resin and 0.05 to 1 part by weight of organic peroxide per 100 parts by weight of these polymer components are added to 100 parts by weight of a peroxide crosslinked polymer consisting of 10 to 90 parts by weight and 90 to 10 parts by weight of polyethylene resin. Then, a polypropylene resin in an amount of 150 to 600 parts by weight, including the amount coexisting during the dynamic heat treatment, per 100 parts by weight of the above-mentioned peroxide crosslinked polymer is added to the processed material obtained by dynamic heat treatment. A method for producing a polypropylene resin composition, which comprises mixing. 2 Peroxide crosslinked olefin copolymer rubber
10 to 200 parts by weight of a peroxide crosslinked polymer consisting of 10 to 90 parts by weight and 90 to 10 parts by weight of polyethylene resin, 10 to 200 parts by weight of polypropylene resin, and 0.05 to 1 part by weight of organic peroxide per 100 parts by weight of these polymer components. In addition, 2 parts by weight or less of a crosslinking agent is added, and the resultant product is subjected to dynamic heat treatment, and the peroxide crosslinked polymer is added to the processed material.
1. A method for producing a polypropylene resin composition, which comprises mixing 150 to 600 parts by weight of polypropylene resin per 100 parts by weight, including the amount coexisting during dynamic heat treatment.